RESUMO
BACKGROUND: B-lines as typical artefacts of lung ultrasound are considered as surrogate measurement for extravascular lung water. However, B-lines develop in the sub-pleural space and do not allow assessment of the whole lung. Here, we present data from the first observational multi-centre study focusing on the correlation between a B-lines score and extravascular lung water in critically ill patients suffering from a variety of diseases. PATIENTS AND METHODS: In 184 adult patients, 443 measurements were obtained. B-lines were counted and expressed in a score which was compared to extravascular lung water, measured by single-indicator transpulmonary thermodilution. Appropriate correlation coefficients were calculated and receiver operating characteristics (ROC-) curves were plotted. RESULTS: Overall, B-lines score was correlated with body weight-indexed extravascular lung water characterized by r = .59. The subgroup analysis revealed a correlation coefficient in patients without an infection of r = .44, in those with a pulmonary infection of r = .75 and in those with an abdominal infection of r = .23, respectively. Using ROC-analysis the sensitivity and specificity of B-lines for detecting an increased extravascular lung water (>10 mL/kg) was 63% and 79%, respectively. In patients with a P/F ratio <200 mm Hg, sensitivity and specificity to predict an increased extravascular lung water was 71% and 93%, respectively. CONCLUSIONS: Assessment of B-lines does not accurately reflect actual extravascular lung water. In presence of an impaired oxygenation, B-lines may reliably indicate increased extravascular lung water as cause of the oxygenation disorders.
Assuntos
Água Extravascular Pulmonar/diagnóstico por imagem , Pneumopatias/diagnóstico por imagem , Ultrassonografia/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Estado Terminal , Feminino , Humanos , Pulmão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade , Termodiluição , Adulto JovemRESUMO
The T-junction of sensory neurons in the dorsal root ganglion (DRG) is a potential impediment to action potential (AP) propagation towards the CNS. Using intracellular recordings from rat DRG neuronal somata during stimulation of the dorsal root, we determined that the maximal rate at which all of 20 APs in a train could successfully transit the T-junction (following frequency) was lowest in C-type units, followed by A-type units with inflected descending limbs of the AP, and highest in A-type units without inflections. In C-type units, following frequency was slower than the rate at which AP trains could be produced in either dorsal root axonal segments or in the soma alone, indicating that the T-junction is a site that acts as a low-pass filter for AP propagation. Following frequency was slower for a train of 20 APs than for two, indicating that a cumulative process leads to propagation failure. Propagation failure was accompanied by diminished somatic membrane input resistance, and was enhanced when Ca(2+)-sensitive K(+) currents were augmented or when Ca(2+)-sensitive Cl(-) currents were blocked. After peripheral nerve injury, following frequencies were increased in axotomized C-type neurons and decreased in axotomized non-inflected A-type neurons. These findings reveal that the T-junction in sensory neurons is a regulator of afferent impulse traffic. Diminished filtering of AP trains at the T-junction of C-type neurons with axotomized peripheral processes could enhance the transmission of activity that is ectopically triggered in a neuroma or the neuronal soma, possibly contributing to pain generation.
Assuntos
Potenciais de Ação/fisiologia , Células Receptoras Sensoriais/fisiologia , Nervos Espinhais/lesões , Nervos Espinhais/fisiopatologia , Animais , Comportamento Animal , Gânglios Espinais/fisiologia , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
One year after the establishment of the rescue service of Graz, Austria, in 1889, twelve young medical students were recruited because of the lack of accredited physicians for emergency care, leading to the foundation of the Medizinercorps Graz. This concept of involving medical students in prehospital emergency care has been retained for more than 120 years, and today the Medizinercorps is integrated into the local Red Cross branch, staffing two emergency ambulance vehicles. The responsible medical officer is called Rettungsmediziner and is an advanced medical student with a specialized emergency medical training of more than 3,000 hours, comprising theoretical lectures; in-hospital clerkships in anesthesia, internal medicine, and surgery; manikin training; and hands-on peer-to-peer teaching during assignments. The local emergency medical system provides at least 10 regular basic ambulance vehicles, the two emergency ambulance vehicles, and two emergency physicians on a 24-hours-a-day/seven-days-a-week basis for about 300,000 people. The emergency ambulance vehicles staffed with a Rettungsmediziner respond to all kinds of possibly life-threatening situations and also provide interhospital transfer of intensive care patients. This entirely volunteer-based system enables extremely high-level prehospital emergency care, saves resources and reduces costs, and employs modern training concepts for the continuing advancement of prehospital emergency care.
Assuntos
Serviços Médicos de Emergência/história , Áustria , História do Século XIX , História do Século XX , História do Século XXI , HumanosRESUMO
Painful nerve injury disrupts levels of cytoplasmic and stored Ca(2+) in sensory neurons. Since influx of Ca(2+) may occur through store-operated Ca(2+) entry (SOCE) as well as voltage- and ligand-activated pathways, we sought confirmation of SOCE in sensory neurons from adult rats and examined whether dysfunction of SOCE is a possible pathogenic mechanism. Dorsal root ganglion neurons displayed a fall in resting cytoplasmic Ca(2+) concentration when bath Ca(2+) was withdrawn, and a subsequent elevation of cytoplasmic Ca(2+) concentration (40 ± 5 nm) when Ca(2+) was reintroduced, which was amplified by store depletion with thapsigargin (1 µm), and was significantly reduced by blockers of SOCE, but was unaffected by antagonists of voltage-gated membrane Ca(2+) channels. We identified the underlying inwardly rectifying Ca(2+)-dependent I(CRAC) (Ca(2+) release activated current), as well as a large thapsigargin-sensitive inward current activated by withdrawal of bath divalent cations, representing SOCE. Molecular components of SOCE, specifically STIM1 and Orai1, were confirmed in sensory neurons at both the transcript and protein levels. Axonal injury by spinal nerve ligation (SNL) elevated SOCE and I(CRAC). However, SOCE was comparable in injured and control neurons when stores were maximally depleted by thapsigargin, and STIM1 and Orai1 levels were not altered by SNL, showing that upregulation of SOCE after SNL is driven by store depletion. Blockade of SOCE increased neuronal excitability in control and injured neurons, whereas injured neurons showed particular dependence on SOCE for maintaining levels of cytoplasmic and stored Ca(2+), which indicates a compensatory role for SOCE after injury.
Assuntos
Canais de Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Gânglios Espinais/metabolismo , Hiperalgesia/metabolismo , Células Receptoras Sensoriais/metabolismo , Nervos Espinhais/lesões , Análise de Variância , Animais , Western Blotting , Células Cultivadas , Gânglios Espinais/citologia , Hiperalgesia/fisiopatologia , Imuno-Histoquímica , Masculino , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Receptoras Sensoriais/citologia , Nervos Espinhais/metabolismoRESUMO
BACKGROUND: The plasma membrane Ca2+-ATPase (PMCA) is the principal means by which sensory neurons expel Ca2+ and thereby regulate the concentration of cytoplasmic Ca2+ and the processes controlled by this critical second messenger. We have previously found that painful nerve injury decreases resting cytoplasmic Ca2+ levels and activity-induced cytoplasmic Ca2+ accumulation in axotomized sensory neurons. Here we examine the contribution of PMCA after nerve injury in a rat model of neuropathic pain. RESULTS: PMCA function was isolated in dissociated sensory neurons by blocking intracellular Ca2+ sequestration with thapsigargin, and cytoplasmic Ca2+ concentration was recorded with Fura-2 fluorometry. Compared to control neurons, the rate at which depolarization-induced Ca2+ transients resolved was increased in axotomized neurons after spinal nerve ligation, indicating accelerated PMCA function. Electrophysiological recordings showed that blockade of PMCA by vanadate prolonged the action potential afterhyperpolarization, and also decreased the rate at which neurons could fire repetitively. CONCLUSION: We found that PMCA function is elevated in axotomized sensory neurons, which contributes to neuronal hyperexcitability. Accelerated PMCA function in the primary sensory neuron may contribute to the generation of neuropathic pain, and thus its modulation could provide a new pathway for peripheral treatment of post-traumatic neuropathic pain.
Assuntos
Axotomia , Membrana Celular/enzimologia , Neuralgia/enzimologia , Neuralgia/patologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Células Receptoras Sensoriais/enzimologia , Nervos Espinhais/patologia , Potenciais de Ação/efeitos dos fármacos , Animais , Cálcio/metabolismo , Membrana Celular/efeitos dos fármacos , Tamanho Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neuralgia/fisiopatologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/antagonistas & inibidores , Ratos , Ratos Sprague-Dawley , Células Receptoras Sensoriais/efeitos dos fármacos , Células Receptoras Sensoriais/patologia , Trocador de Sódio e Cálcio/metabolismo , Nervos Espinhais/efeitos dos fármacos , Nervos Espinhais/enzimologia , Nervos Espinhais/fisiopatologia , Tapsigargina/farmacologiaRESUMO
Painful axotomy decreases K(ATP) channel current (IK(ATP)) in primary afferent neurons. Because cytosolic Ca(2+) signaling is depressed in injured dorsal root ganglia (DRG) neurons, we investigated whether Ca(2+)-calmodulin (CaM)-Ca(2+)/CaM-dependent kinase II (CaMKII) regulates IK(ATP) in large DRG neurons. Immunohistochemistry identified the presence of K(ATP) channel subunits SUR1, SUR2, and Kir6.2 but not Kir6.1, and pCaMKII in neurofilament 200-positive DRG somata. Single-channel recordings from cell-attached patches revealed that basal and evoked IK(ATP) by ionomycin, a Ca(2+) ionophore, is activated by CaMKII. In axotomized neurons from rats made hyperalgesic by spinal nerve ligation (SNL), basal K(ATP) channel activity was decreased, and sensitivity to ionomycin was abolished. Basal and Ca(2+)-evoked K(ATP) channel activity correlated inversely with the degree of hyperalgesia induced by SNL in the rats from which the neurons were isolated. Inhibition of IK(ATP) by glybenclamide, a selective K(ATP) channel inhibitor, depolarized resting membrane potential (RMP) recorded in perforated whole-cell patches and enhanced neurotransmitter release measured by amperometry. The selective K(ATP) channel opener diazoxide hyperpolarized the RMP and attenuated neurotransmitter release. Axotomized neurons from rats made hyperalgesic by SNL lost sensitivity to the myristoylated form of autocamtide-2-related inhibitory peptide (AIPm), a pseudosubstrate blocker of CaMKII, whereas axotomized neurons from SNL animals that failed to develop hyperalgesia showed normal IK(ATP) inhibition by AIPm. AIPm also depolarized RMP in control neurons via K(ATP) channel inhibition. Unitary current conductance and sensitivity of K(ATP) channels to cytosolic ATP and ligands were preserved even after painful nerve injury, thus providing opportunities for selective therapeutic targeting against neuropathic pain.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Cálcio/metabolismo , Calmodulina/metabolismo , Hiperalgesia/metabolismo , Canais KATP/metabolismo , Neurônios Aferentes/metabolismo , Animais , Axotomia , Sistema Livre de Células , Fenômenos Eletrofisiológicos , Gânglios Espinais/metabolismo , Ionomicina/farmacologia , Masculino , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-DawleyRESUMO
Prognostication after cardiopulmonary resuscitation (CPR) is complex. Novel biomarkers like soluble suppression of tumorigenicity 2 (sST2) may provide an objective approach. A total of 106 post-CPR patients were included in this single-center observational prospective study. Serum sST2 levels were obtained 24 h after admission. Individuals were assigned to two groups: patients below and above the overall cohort's median sST2 concentration. Primary outcome was a combined endpoint at 6 months (death or Cerebral Performance Category > 2); secondary endpoint 30-day mortality. A uni- and multivariate logistic regression analysis were conducted. Elevated sST2-levels were associated with an increased risk for the primary outcome (OR 1.011, 95% CI 1.004-1.019, p = 0.004), yet no patients with poor neurological outcome were observed at 6 months. The optimal empirical cut-off for sST2 was 46.15 ng/ml (sensitivity 81%, specificity 53%, AUC 0.69). Levels above the median (> 53.42 ng/ml) were associated with higher odds for both endpoints (death or CPC > 2 after 6 months: 21% vs. 49%, OR 3.59, 95% CI 1.53-8.45, p = 0.003; death after 30 days: 17% vs. 43.3%, OR 3.75, 95% CI 1.52-9.21, p = 0.003). A positive correlation of serum sST2 after CPR with mortality at 30 days and 6 months after cardiac arrest could be demonstrated.
Assuntos
Reanimação Cardiopulmonar/mortalidade , Proteína 1 Semelhante a Receptor de Interleucina-1/sangue , Idoso , Biomarcadores/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
BACKGROUND: ATP-sensitive potassium (KATP) channels in neurons mediate neuroprotection, they regulate membrane excitability, and they control neurotransmitter release. Because loss of DRG neuronal KATP currents is involved in the pathophysiology of pain after peripheral nerve injury, we characterized the distribution of the KATP channel subunits in rat DRG, and determined their alterations by painful axotomy using RT-PCR, immunohistochemistry and electron microscopy. RESULTS: PCR demonstrated Kir6.1, Kir6.2, SUR1 and SUR2 transcripts in control DRG neurons. Protein expression for all but Kir6.1 was confirmed by Western blots and immunohistochemistry. Immunostaining of these subunits was identified by fluorescent and confocal microscopy in plasmalemmal and nuclear membranes, in the cytosol, along the peripheral fibers, and in satellite glial cells. Kir6.2 co-localized with SUR1 subunits. Kir6.2, SUR1, and SUR2 subunits were identified in neuronal subpopulations, categorized by positive or negative NF200 or CGRP staining. KATP current recorded in excised patches was blocked by glybenclamide, but preincubation with antibody against SUR1 abolished this blocking effect of glybenclamide, confirming that the antibody targets the SUR1 protein in the neuronal plasmalemmal membrane. In the myelinated nerve fibers we observed anti-SUR1 immunostaining in regularly spaced funneled-shaped structures. These structures were identified by electron microscopy as Schmidt-Lanterman incisures (SLI) formed by the Schwann cells. Immunostaining against SUR1 and Kir6.2 colocalized with anti-Caspr at paranodal sites.DRG excised from rats made hyperalgesic by spinal nerve ligation exhibited similar staining against Kir6.2, SUR1 or SUR2 as DRG from controls, but showed decreased prevalence of SUR1 immunofluorescent NF200 positive neurons. In DRG and dorsal roots proximal to axotomy SLI were smaller and showed decreased SUR1 immunofluorescence. CONCLUSIONS: We identified Kir6.2/SUR1 and Kir6.2/SUR2 KATP channels in rat DRG neuronal somata, peripheral nerve fibers, and glial satellite and Schwann cells, in both normal state and after painful nerve injury. This is the first report of KATP channels in paranodal sites adjacent to nodes of Ranvier and in the SLI of the Schwann cells. After painful axotomy KATP channels are downregulated in large, myelinated somata and also in SLI, which are also of smaller size compared to controls.Because KATP channels may have diverse functional roles in neurons and glia, further studies are needed to explore the potential of KATP channels as targets of therapies against neuropathic pain and neurodegeneration.
Assuntos
Gânglios Espinais/metabolismo , Canais KATP/metabolismo , Neuralgia/metabolismo , Doenças do Sistema Nervoso Periférico/metabolismo , Células Receptoras Sensoriais/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Axotomia/efeitos adversos , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Gânglios Espinais/ultraestrutura , Glibureto/farmacologia , Hipoglicemiantes/farmacologia , Imuno-Histoquímica , Canais KATP/genética , Masculino , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Neuralgia/etiologia , Neuralgia/fisiopatologia , Proteínas de Neurofilamentos/metabolismo , Doenças do Sistema Nervoso Periférico/etiologia , Doenças do Sistema Nervoso Periférico/fisiopatologia , Canais de Potássio Corretores do Fluxo de Internalização/genética , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Nós Neurofibrosos/metabolismo , Nós Neurofibrosos/ultraestrutura , Ratos , Ratos Sprague-Dawley , Receptores de Droga/genética , Receptores de Droga/metabolismo , Células de Schwann/metabolismo , Células de Schwann/ultraestrutura , Células Receptoras Sensoriais/ultraestrutura , Receptores de SulfonilureiasRESUMO
BACKGROUND: Ca is the dominant second messenger in primary sensory neurons. In addition, disrupted Ca signaling is a prominent feature in pain models involving peripheral nerve injury. Standard cytoplasmic Ca recording techniques use high K or field stimulation and dissociated neurons. To compare findings in intact dorsal root ganglia, we used a method of simultaneous electrophysiologic and microfluorimetric recording. METHODS: Dissociated neurons were loaded by bath-applied Fura-2-AM and subjected to field stimulation. Alternatively, we adapted a technique in which neuronal somata of intact ganglia were loaded with Fura-2 through an intracellular microelectrode that provided simultaneous membrane potential recording during activation by action potentials (APs) conducted from attached dorsal roots. RESULTS: Field stimulation at levels necessary to activate neurons generated bath pH changes through electrolysis and failed to predictably drive neurons with AP trains. In the intact ganglion technique, single APs produced measurable Ca transients that were fourfold larger in presumed nociceptive C-type neurons than in nonnociceptive Abeta-type neurons. Unitary Ca transients summated during AP trains, forming transients with amplitudes that were highly dependent on stimulation frequency. Each neuron was tuned to a preferred frequency at which transient amplitude was maximal. Transients predominantly exhibited monoexponential recovery and had sustained plateaus during recovery only with trains of more than 100 APs. Nerve injury decreased Ca transients in C-type neurons, but increased transients in Abeta-type neurons. CONCLUSIONS: Refined observation of Ca signaling is possible through natural activation by conducted APs in undissociated sensory neurons and reveals features distinct to neuronal types and injury state.
Assuntos
Sinalização do Cálcio , Gânglios Espinais/lesões , Gânglios Espinais/metabolismo , Células Receptoras Sensoriais/metabolismo , Potenciais de Ação , Animais , Bloqueadores dos Canais de Cálcio , Canais de Cálcio , Citofotometria/métodos , Fura-2/administração & dosagem , Fura-2/análogos & derivados , Concentração de Íons de Hidrogênio , Masculino , Potenciais da Membrana , Fibras Nervosas , Neurônios Aferentes , Ratos , Ratos Sprague-DawleyRESUMO
The continuity of chest compression is the main challenge in prehospital cardiopulmonary resuscitation in the field as well as during transport. Invasive blood pressure monitoring with visible pulse waves by means of an arterial line set prehospitally allows for tight control of the effectiveness of chest compressions as well as of the impact of the administered epinephrine and also captures beginning fatigue of the rescuers. In this case, maintaining uninterrupted circulation through manual as well as mechanical chest compressions continued until the successful percutaneous coronary intervention saved the patients life without neurologic damage.
Assuntos
Monitores de Pressão Arterial , Cateterismo Cardíaco , Reanimação Cardiopulmonar , Parada Cardíaca/diagnóstico , Parada Cardíaca/terapia , Massagem Cardíaca , Idoso , Resgate Aéreo , Determinação da Pressão Arterial/instrumentação , Serviço Hospitalar de Emergência , Parada Cardíaca/etiologia , Humanos , MasculinoRESUMO
BACKGROUND: ATP-sensitive potassium (KATP) channels in neurons regulate excitability, neurotransmitter release and mediate protection from cell-death. Furthermore, activation of KATP channels is suppressed in DRG neurons after painful-like nerve injury. NO-dependent mechanisms modulate both KATP channels and participate in the pathophysiology and pharmacology of neuropathic pain. Therefore, we investigated NO modulation of KATP channels in control and axotomized DRG neurons. RESULTS: Cell-attached and cell-free recordings of KATP currents in large DRG neurons from control rats (sham surgery, SS) revealed activation of KATP channels by NO exogenously released by the NO donor SNAP, through decreased sensitivity to [ATP]i. This NO-induced KATP channel activation was not altered in ganglia from animals that demonstrated sustained hyperalgesia-type response to nociceptive stimulation following spinal nerve ligation. However, baseline opening of KATP channels and their activation induced by metabolic inhibition was suppressed by axotomy. Failure to block the NO-mediated amplification of KATP currents with specific inhibitors of sGC and PKG indicated that the classical sGC/cGMP/PKG signaling pathway was not involved in the activation by SNAP. NO-induced activation of KATP channels remained intact in cell-free patches, was reversed by DTT, a thiol-reducing agent, and prevented by NEM, a thiol-alkylating agent. Other findings indicated that the mechanisms by which NO activates KATP channels involve direct S-nitrosylation of cysteine residues in the SUR1 subunit. Specifically, current through recombinant wild-type SUR1/Kir6.2 channels expressed in COS7 cells was activated by NO, but channels formed only from truncated isoform Kir6.2 subunits without SUR1 subunits were insensitive to NO. Further, mutagenesis of SUR1 indicated that NO-induced KATP channel activation involves interaction of NO with residues in the NBD1 of the SUR1 subunit. CONCLUSION: NO activates KATP channels in large DRG neurons via direct S-nitrosylation of cysteine residues in the SUR1 subunit. The capacity of NO to activate KATP channels via this mechanism remains intact even after spinal nerve ligation, thus providing opportunities for selective pharmacological enhancement of KATP current even after decrease of this current by painful-like nerve injury.
Assuntos
Ativação do Canal Iônico/efeitos dos fármacos , Canais KATP/metabolismo , Mamíferos/metabolismo , Óxido Nítrico/farmacologia , Células Receptoras Sensoriais/efeitos dos fármacos , Células Receptoras Sensoriais/metabolismo , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Células COS , Chlorocebus aethiops , GMP Cíclico/análogos & derivados , GMP Cíclico/farmacologia , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Cisteína/genética , Gânglios Espinais/citologia , Gânglios Espinais/metabolismo , Masculino , Mutação/genética , Óxido Nítrico/metabolismo , Nitrosação/efeitos dos fármacos , Técnicas de Patch-Clamp , Canais de Potássio Corretores do Fluxo de Internalização/química , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Estrutura Terciária de Proteína , Ratos , Receptores de Droga/química , Receptores de Droga/metabolismo , Proteínas Recombinantes/metabolismo , S-Nitroso-N-Acetilpenicilamina/farmacologia , Células Receptoras Sensoriais/enzimologia , Receptores de SulfonilureiasRESUMO
BACKGROUND: Painful nerve injury leads to disrupted Ca signaling in primary sensory neurons, including decreased endoplasmic reticulum (ER) Ca storage. This study examines potential causes and functional consequences of Ca store limitation after injury. METHODS: Neurons were dissociated from axotomized fifth lumbar (L5) and the adjacent L4 dorsal root ganglia after L5 spinal nerve ligation that produced hyperalgesia, and they were compared to neurons from control animals. Intracellular Ca levels were measured with Fura-2 microfluorometry, and ER was labeled with probes or antibodies. Ultrastructural morphology was analyzed by electron microscopy of nondissociated dorsal root ganglia, and intracellular electrophysiological recordings were obtained from intact ganglia. RESULTS: Live neuron staining with BODIPY FL-X thapsigargin (Invitrogen, Carlsbad, CA) revealed a 40% decrease in sarco-endoplasmic reticulum Ca-ATPase binding in axotomized L5 neurons and a 34% decrease in L4 neurons. Immunocytochemical labeling for the ER Ca-binding protein calreticulin was unaffected by injury. Total length of ER profiles in electron micrographs was reduced by 53% in small axotomized L5 neurons, but it was increased in L4 neurons. Cisternal stacks of ER and aggregation of ribosomes occurred less frequently in axotomized neurons. Ca-induced Ca release, examined by microfluorometry with dantrolene, was eliminated in axotomized neurons. Pharmacologic blockade of Ca-induced Ca release with dantrolene produced hyperexcitability in control neurons, confirming its functional importance. CONCLUSIONS: After axotomy, ER Ca stores are reduced by anatomic loss and possibly diminished sarco-endoplasmic reticulum Ca-ATPase. The resulting disruption of Ca-induced Ca release and protein synthesis may contribute to the generation of neuropathic pain.
Assuntos
Cálcio/metabolismo , Células Receptoras Sensoriais/metabolismo , Animais , Compostos de Boro , Calbindina 2 , Cálcio/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Citoplasma/efeitos dos fármacos , Citoplasma/metabolismo , Dantroleno/farmacologia , Eletrofisiologia , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/ultraestrutura , Corantes Fluorescentes , Hiperalgesia/patologia , Imuno-Histoquímica , Ligadura , Masculino , Microscopia Eletrônica , Medição da Dor/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Proteína G de Ligação ao Cálcio S100/metabolismo , Células Receptoras Sensoriais/efeitos dos fármacos , Células Receptoras Sensoriais/ultraestrutura , Nervos Espinhais/efeitos dos fármacos , Nervos Espinhais/metabolismo , Nervos Espinhais/ultraestruturaRESUMO
BACKGROUND: The cellular mechanisms of neuropathic pain are inadequately understood. Previous investigations have revealed disrupted Ca signaling in primary sensory neurons after injury. The authors examined the effect of injury on intracellular Ca stores of the endoplasmic reticulum, which critically regulate the Ca signal and neuronal function. METHODS: Intracellular Ca levels were measured with Fura-2 or mag-Fura-2 microfluorometry in axotomized fifth lumbar (L5) dorsal root ganglion neurons and adjacent L4 neurons isolated from hyperalgesic rats after L5 spinal nerve ligation, compared to neurons from control animals. RESULTS: Endoplasmic reticulum Ca stores released by the ryanodine-receptor agonist caffeine decreased by 46% in axotomized small neurons. This effect persisted in Ca-free bath solution, which removes the contribution of store-operated membrane Ca channels, and after blockade of the mitochondrial, sarco-endoplasmic Ca-ATPase and the plasma membrane Ca ATPase pathways. Ca released by the sarco-endoplasmic Ca-ATPase blocker thapsigargin and by the Ca-ionophore ionomycin was also diminished by 25% and 41%, respectively. In contrast to control neurons, Ca stores in axotomized neurons were not expanded by neuronal activation by K depolarization, and the proportionate rate of refilling by sarco-endoplasmic Ca-ATPase was normal. Luminal Ca concentration was also reduced by 38% in axotomized neurons in permeabilized neurons. The adjacent neurons of the L4 dorsal root ganglia showed modest and inconsistent changes after L5 spinal nerve ligation. CONCLUSIONS: Painful nerve injury leads to diminished releasable endoplasmic reticulum Ca stores and a reduced luminal Ca concentration. Depletion of Ca stores may contribute to the pathogenesis of neuropathic pain.
Assuntos
Axotomia , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/fisiologia , Animais , Axônios/patologia , Cafeína/farmacologia , Capsaicina/farmacologia , Células Cultivadas , Estimulantes do Sistema Nervoso Central/farmacologia , Retículo Endoplasmático/fisiologia , Hiperalgesia/patologia , Ionomicina/farmacologia , Ligadura , Masculino , Degeneração Neural/patologia , Medição da Dor , Ratos , Ratos Sprague-Dawley , Canal de Liberação de Cálcio do Receptor de Rianodina/efeitos dos fármacos , Nervo Isquiático/lesões , Nervos Espinhais/lesões , Tapsigargina/farmacologiaRESUMO
BACKGROUND: Little is known regarding the final needle tip location when various intensities of nerve stimulation are used to guide block needle insertion. Therefore, in control and hyperglycemic dogs, the authors examined whether lower-intensity stimulation results in injection closer to the sciatic nerve than higher-threshold stimulation. METHODS: During anesthesia, the sciatic nerve was approached with an insulated nerve block needle emitting either 1 mA (high-current group, n = 9) or 0.5 mA (low-current group, n = 9 in control dogs and n = 6 in hyperglycemic dogs). After positioning to obtain a distal motor response, the lowest current producing a response was identified, and ink (0.5 ml) was injected. Frozen sections of the tissue revealed whether the ink was in contact with the epineurium of the nerve, distant to it, or within it. RESULTS: In control dogs, the patterns of distribution using high-threshold (final current 0.99 +/- 0.03 mA, mean +/- SD) and low-threshold (final current 0.33 +/- 0.08 mA) stimulation equally showed ink that was in contact with the epineurium or distant to it. One needle placement in the high-threshold group resulted in intraneural injection. In hyperglycemic dogs, all needle insertions used a low-threshold technique (n = 6, final threshold 0.35 +/- 0.08 mA), and all resulted in intraneural injections. CONCLUSIONS: In normal dogs, current stimulation levels in the range of 0.33-1.0 mA result in needle placement comparably close to the sciatic nerve but do not correlate with distance from the target nerve. In this experimental design, low-threshold electrical stimulation does not offer satisfactory protection against intraneural injection in the presence of hyperglycemia.
Assuntos
Corantes/administração & dosagem , Estimulação Elétrica/métodos , Hiperglicemia/fisiopatologia , Agulhas , Nervo Isquiático/fisiopatologia , Animais , Corantes/farmacocinética , Modelos Animais de Doenças , Cães , Modelos Animais , Nervos Periféricos/fisiologia , Nervos Periféricos/fisiopatologia , Projetos Piloto , Distribuição Aleatória , Nervo Isquiático/fisiologiaRESUMO
BACKGROUND: We have previously shown that a decrease of inward Ca(2+) flux (I(Ca)) across the sensory neuron plasmalemma, such as happens after axotomy, increases neuronal excitability. From this, we predicted that increasing I(Ca) in injured neurons should correct their hyperexcitability. METHODS: The influence of increased or decreased I(Ca) upon membrane biophysical variables and excitability was determined during recording from A-type neurons in nondissociated dorsal root ganglia after spinal nerve ligation using an intracellular recording technique. RESULTS: When the bath Ca(2+) level was increased to promote I(Ca), the after-hyperpolarization was decreased and repetitive firing was suppressed, which also followed amplification of Ca(2+)-activated K(+) current with selective agents NS1619 and NS309. A decreased external bath Ca(2+) concentration had the opposite effects, similar to previous observations in uninjured neurons. CONCLUSIONS: These findings indicate that at least a part of the hyperexcitability of somatic sensory neurons after axotomy is attributable to diminished inward Ca(2+) flux, and that measures to restore I(Ca) may potentially be therapeutic for painful peripheral neuropathy.
Assuntos
Cálcio/metabolismo , Gânglios Espinais/embriologia , Neurônios/metabolismo , Animais , Comportamento Animal , Benzimidazóis/farmacologia , Cálcio/química , Indóis/farmacologia , Masculino , Modelos Biológicos , Neurônios Aferentes/metabolismo , Oximas/farmacologia , Potássio/química , Ratos , Ratos Sprague-Dawley , Nervos Espinhais/patologiaRESUMO
Store-operated Ca2+ entry (SOCE) is a Ca2+ influx pathway at the plasma membrane that replenishes intracellular Ca2+ stores in response to depletion of Ca2+ stores. The SOC current, also known as the Ca2+ release-activated Ca2+ current (ICRAC), has a small conductance, which makes selective recording difficult. This challenge may be addressed using techniques based on identification of Ca2+ influx patch-clamp electrophysiological recording and measurement of cytoplasmic Ca2+ accumulation with Ca2+-sensitive fluorophores. Here, we describe specific methods for studying SOCE using these approaches in rat dorsal root ganglion neurons.
Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Citofotometria , Imagem Molecular , Neurônios/fisiologia , Técnicas de Patch-Clamp , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/genética , Canais de Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Citofotometria/métodos , Fenômenos Eletrofisiológicos , Ativação do Canal Iônico , Camundongos , Imagem Molecular/métodos , Neurônios/efeitos dos fármacos , Ratos , Análise de Célula ÚnicaRESUMO
BACKGROUND: 1,3-beta-D Glucan (BDG) assay has good accuracy for distinguishing patients with invasive fungal infections from patients without. Some procedures and medications affect BDG levels, resulting in false-positive BDG results. The extent of intestinal surgery on BDG kinetics is unknown. We evaluated the influence of laparoscopic and open intestinal surgery on peri- and postsurgical serum BDG values. METHODS: BDG was determined in 346 samples from 50 patients undergoing laparoscopic (24) or open (26) intestinal surgery at the following time points: after insertion of arterial but before skin incision, after skin incision but before dissection of the intestinal mucosa, after completion of anastomosis, after completion of skin sutures, in the evening after surgery, day 2 after surgery, 4-5 days after surgery. RESULTS: BDG was positive (ie, concentration ≥80 pg/mL) in 54% to 61% of patients during laparoscopic and open surgery (highest rates after completion of skin sutures). BDG was still positive in 12% (open) to 17% (laparoscopic) of patients without any suspected or proven fungal infection or anastomotic leakage 4-5 days after surgery. After completion of gut anastomosis, the BDG increase was higher in open compared with laparoscopic intestinal surgery. CONCLUSIONS: The value of positive BDG tests in the perioperative setting up to 5 days postsurgery seems to be limited due to BDG elevations from intestinal surgical procedures.
RESUMO
PURPOSE: An arterial blood gas analysis (ABG) yields important diagnostic information in the management of cardiac arrest. This study evaluated ABG samples obtained during out-of-hospital cardiopulmonary resuscitation (OHCPR) in the setting of a prospective multicenter trial. We aimed to clarify prospectively the ABG characteristics during OHCPR, potential prognostic parameters and the ABG dynamics after return of spontaneous circulation (ROSC). METHODS: ABG samples were collected and instantly processed either under ongoing OHCPR performed according to current advanced life support guidelines or immediately after ROSC and data ware entered into a case report form along with standard CPR parameters. RESULTS: During a 22-month observation period, 115 patients had an ABG analysis during OHCPR. In samples obtained under ongoing CPR, an acidosis was present in 98% of all cases, but was mostly of mixed hypercapnic and metabolic origin. Hypocapnia was present in only 6% of cases. There was a trend towards higher paO2 values in patients who reached sustained ROSC, and a multivariate regression analysis revealed age, initial rhythm, time from collapse to CPR initiation and the arterio-alveolar CO2 difference (AaDCO2) to be associated with sustained ROSC. ABG samples drawn immediately after ROSC demonstrated higher paO2 and unaltered pH and base excess levels compared with samples collected during ongoing CPR. CONCLUSIONS: Our findings suggest that adequate ventilation and oxygenation deserve more research and clinical attention in the management of cardiac arrest and that oxygen uptake improves within minutes after ROSC. Hyperventilation resulting in arterial hypocapnia is not a major problem during OHCPR.
Assuntos
Gasometria/estatística & dados numéricos , Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar/sangue , Acidose/sangue , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/mortalidade , Parada Cardíaca Extra-Hospitalar/terapia , Estudos Prospectivos , Fatores de TempoRESUMO
AIM: As recent clinical data suggest a harmful effect of arterial hyperoxia on patients after resuscitation from cardiac arrest (CA), we aimed to investigate this association during cardiopulmonary resuscitation (CPR), the earliest and one of the most crucial phases of recirculation. METHODS: We analysed 1015 patients who from 2003 to 2010 underwent out-of-hospital CPR administered by emergency medical services serving 300,000 inhabitants. Inclusion criteria for further analysis were nontraumatic background of CA and patients >18 years of age. One hundred and forty-five arterial blood gas analyses including oxygen partial pressure (paO2) measurement were obtained during CPR. RESULTS: We observed a highly significant increase in hospital admission rates associated with increases in paO2 in steps of 100 mmHg (13.3 kPa). Subsequently, data were clustered according to previously described cutoffs (≤ 60 mmHg [8 kPa]], 61-300 mmHg [8.1-40 kPa], >300 mmHg [>40 kPa]). Baseline variables (age, sex, initial rhythm, rate of bystander CPR and collapse-to-CPR time) of the three compared groups did not differ significantly. Rates of hospital admission after CA were 18.8%, 50.6% and 83.3%, respectively. In a multivariate analysis, logistic regression revealed significant prognostic value for paO2 and the duration of CPR. CONCLUSION: This study presents novel human data on the arterial paO2 during CPR in conjunction with the rate of hospital admission. We describe a significantly increased rate of hospital admission associated with increasing paO2. We found that the previously described potentially harmful effects of hyperoxia after return of spontaneous circulation were not reproduced for paO2 measured during CPR. CLINICAL TRIAL REGISTRATION: n/a.