Effects on cerebral blood flow of position changes, hyperoxia, CO2 partial pressure variations and the Valsalva manoeuvre: A study in healthy volunteers.

BACKGROUND: Maintaining adequate blood pressure to ensure proper cerebral blood flow (CBF) during surgery is challenging. Induced mild hypotension, sitting position or unavoidable intra-operative circumstances such as haemorrhage, added to variations in carbon dioxide and oxygen tensions, may influence perfusion. Several of these circumstances may coincide and it is unclear how these may affect CBF. OBJECTIVE: To describe the variation in transcranial Doppler and regional cerebral oxygen saturation (rSO2), as a surrogate of CBF, after cardiac preload and gravitational positional changes. DESIGN: Observational study. SETTING: Operating room at Hospital Clínic de Barcelona. VOLUNTEERS: Ten healthy volunteers, white, both sexes. INTERVENTIONS: Measurements were performed in the supine, sitting and standing positions during hyperoxia, hypocapnia and hypercapnia protocols and after a Valsalva manoeuvre. MAIN OUTCOME MEASURES: Cardiac index (CI), haemodynamic and respiratory variables, maximal and mean velocities (Vmax, Vmean) (transcranial Doppler) and rSO2 were acquired. Results were analysed using a generalised estimating equation technique. RESULTS: CI increases more than 16% after a preload challenge were not accompanied by differences in rSO2 or Vmax - Vmean. With positional changes, Vmean decreased more than 7% (P = 0.042) from the supine to the seated position. Hyperoxia induced a cerebral rSO2 increase more than 6% (P = 0.0001) with decreases in Vmax, Vmean and CI values more than 3% (P = 0.001, 0.022 and 0.001) in the supine and standing position. During hypocapnia, CI rose more than 20% from supine to seated and standing (P = 0.0001) with a 4.5% decrease in cerebral rSO2 (P = 0.001) and a decrease of Vmax - Vmean more than 24% in all positions (P = 0.001). Hypercapnia increased cerebral rSO2 more than 17% (P = 0.001), Vmax - Vmean more than 30% (P = 0.001) with no changes in CI. After a Valsalva manoeuvre, rSO2 decreased more than 3% in the right hemisphere in the upright position (P = 0.001). Vmax - Vmean decreased more than 10% (P = 0.001) with no changes in CI. CONCLUSION: CBF changes in response to cerebral vasoconstriction and vasodilatation were detected with rSO2 and transcranial Doppler in healthy volunteers during cardiac preload and in different body positions. Acute hypercapnia had a greater effect on recorded brain parameters than hypocapnia.

Predictors of severe asthma attack re-attendance in Ecuadorian children: a cohort study.

Asthma is a common cause of emergency care attendance in low- and middle-income countries (LMICs). While few prospective studies of predictors for emergency care attendance have been undertaken in high-income countries, none have been performed in a LMIC.We followed a cohort of 5-15-year-old children treated for asthma attacks in emergency rooms of public health facilities in Esmeraldas City, Ecuador. We collected blood and nasal wash samples, and performed spirometry and exhaled nitric oxide fraction measurements. We explored potential predictors for recurrence of severe asthma attacks requiring emergency care over 6 months' follow-up.We recruited 283 children of whom 264 (93%) were followed-up for ≥6 months or until their next asthma attack. Almost half (46%) had a subsequent severe asthma attack requiring emergency care. Predictors of recurrence in adjusted analyses were (adjusted OR, 95% CI) younger age (0.87, 0.79-0.96 per year), previous asthma diagnosis (2.2, 1.2-3.9), number of parenteral corticosteroid courses in previous year (1.3, 1.1-1.5), food triggers (2.0, 1.1-3.6) and eczema diagnosis (4.2, 1.02-17.6). A parsimonious Cox regression model included the first three predictors plus urban residence as a protective factor (adjusted hazard ratio 0.69, 95% CI 0.50-0.95). Laboratory and lung function tests did not predict recurrence.Factors independently associated with recurrent emergency attendance for asthma attacks were identified in a low-resource LMIC setting. This study suggests that a simple risk-assessment tool could potentially be created for emergency rooms in similar settings to identify higher-risk children on whom limited resources might be better focused.

Experience with "Fast track" postoperative care after deep brain stimulation surgery.

BACKGROUND: A 24-h-stay in the post-anesthesia care unit (PACU) is a common postoperative procedure after deep brain stimulation surgery (DBS). OBJECTIVE: We evaluated the impact of a fast-track (FT) postoperative care protocol. METHODS: An analysis was performed on all patients who underwent DBS in 2 periods: 2006, overnight monitored care (OMC group), and 2007-2013, FT care (FT group). RESULTS: The study included 19 patients in OMC and 95 patients in FT. Intraoperative complications occurred in 26.3% patients in OMC vs. 35.8% in FT. Post-operatively, one patient in OMC developed hemiparesis, and agitation in 2 patients. In FT, two patients with intraoperative hemiparesis were transferred to the ICU. While on the ward, 3 patients from the FT developed hemiparesis, two of them 48h after the procedure. Thirty eight percent of FT had an MRI scan, while the remaining 62% and all patients of OMC had a CT-scan performed on their transfer to the ward. One patient in OMC had a subthalamic hematoma. Two patients in FT had a pallidal hematoma, and 3 a bleeding along the electrode. CONCLUSIONS: A FT discharge protocol is a safe postoperative care after DBS. There are a small percentage of complications after DBS, which mainly occur within the first 6h.

Binding Selectivity of Macrocycle Ionophores in Ionic Liquids versus Aqueous Solution and Solvent-free Conditions.

The understanding of supramolecular recognition in room-temperature ionic liquids (RTILs) is key to develop the full potential of these materials. In this work, we provide insights into the selectivity of the binding of alkali metal cations by standard cyclodextrin and calixarene macrocycles in RTILs. A direct laser desorption/ionization mass spectrometry approach is employed to determine the relative abundances of the inclusion complexes formed through competitive binding in RTIL solutions. The results are compared with the binding selectivities measured under solvent-free conditions and in water/methanol solutions. Cyclodextrins and calixarenes in which the peripheral OH groups are substituted by bulkier side groups preferentially bind to Cs(+) . Such specific ionophoric behavior is substantially enhanced by solvation effects in the RTIL. This finding is rationalized with the aid of quantum mechanical calculations, in terms of the conformational features and steric interactions that drive the solvation of the inclusion complexes by the bulky RTIL counterions.

[Diagnostic yield and postoperative management of patients submitted to brain biopsy in a university hospital]. / Eficacia diagnóstica y manejo posoperatorio de los pacientes sometidos a biopsia cerebral en un hospital universitario.

OBJECTIVE: To assess the diagnostic yield and the incidence of perioperative complications in patients undergoing an open or closed cerebral biopsy and to determine the length of intensive care monitoring, for early diagnosis and fast management of perioperative complications. MATERIAL AND METHOD: This was a retrospective analysis of all the patients that underwent brain biopsy between January 2006 and July 2012. We recorded demographic data, comorbidities, modality of biopsy, intraoperative clinical data, histological results, computed tomography scanning findings and occurrence, and type of perioperative complications and moment of appearance. RESULTS: Seventy-six brain biopsies in 75 consecutive patients (51 closed and 25 open) were analysed. Diagnostic yield was 98% for closed biopsies and 96% for open biopsies. Mortality related to the procedures was 3.9 and 4%, respectively. The incidence of major complications was 3.9% for closed biopsies and 8% for open biopsies; half of these appeared within the first 24 postoperative hours, during patient stay in the Intensive Care Unit. Age was the only risk factor for complications (P=.04) in our study. No differences in morbimortality were found between the studied groups. CONCLUSIONS: Diagnostic yield was very high in our series. Because the importance of early diagnosis of complications for preventing long-term sequelae, we recommend overnight hospital stay for observation after open or closed brain biopsy.

[Detection of venous air embolism and patent foramen ovale in neurosurgery patients in sitting position]. / Detección de embolismo aéreo venoso y de foramen oval permeable en pacientes neuroquirúrgicos intervenidos en posición de sedestación.

INTRODUCTION: Early detection of venous air embolism (VAE) during neurosurgical procedures in sitting position decreases the severity of its complications. OBJECTIVES: our aim was to analyse the detection of VAE and its impact on patients operated in a sitting position, verify air aspiration through a central venous catheter and assess the feasibility of the routine use of transcranial Doppler (TCD) for intraoperative diagnosis of patent foramen ovale (PFO). MATERIAL AND METHODS: We performed a prospective study of consecutive neurosurgical procedures performed in the sitting position for 5 years. Precordial Doppler and end-tidal carbon dioxide were the diagnostic methods for VAE. PFO was explored by TCD after anaesthetic induction. RESULTS: 136 patients were operated in the sitting position, 93 craniotomies and 43 cervical spine procedures. Twenty-two patients (16.2%) were diagnosed with VAE (21.5% of craniotomies and 4.7% of spinal surgeries; p=.013). In 59% of cases, air was aspirated through the central venous catheter. There was haemodynamic involvement in 3 patients, impaired oxygenation in 4 and clinically relevant pneumocephalus in 5 of them. Two patients (1.4%) were diagnosed with PFO, but did not present episodes of VAE or paradoxical air embolism. CONCLUSIONS: The series analysed confirmed a higher incidence of VAE in craniotomies than in cervical spine surgery in a sitting position. We were able to aspirate air through the central venous catheter in more than half the cases. No patients suffered critical intraoperative complications following our approach. The low incidence of PFO detected with TCD will imply a modification of our protocol performed on anaesthetised patients.

Cations in a molecular funnel: vibrational spectroscopy of isolated cyclodextrin complexes with alkali metals.

The benchmark inclusion complexes formed by α-cyclodextrin (αCD) with alkali-metal cations are investigated under isolated conditions in the gas phase. The relative αCD-M(+) (M=Li(+), Na(+), K(+), Cs(+)) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry, infrared action spectroscopy and quantum chemical computations. Solvent-free laser desorption measurements reveal a trend of decreasing stability of the isolated complexes with increasing size of the cation guest. The experimental infrared spectra are qualitatively similar for the complexes with the four cations investigated, and are consistent with the binding of the cation within the primary face of the cyclodextrin, as predicted by the quantum computations (B3LYP/6-31+G*). The inclusion of the quantum-chemical cation disrupts the C(6) symmetry of the free cyclodextrin to provide the optimum coordination of the cations with the -CH(2)OH groups in C(1), C(2) or C(3) symmetry arrangements that are determined by the size of the cation.

Lysyl oxidase-like-2 (LOXL2) is a major isoform in chondrocytes and is critically required for differentiation.

The lysyl oxidase family is made up of five members: lysyl oxidase (LOX) and lysyl oxidase-like 1-4 (LOXL1-LOXL4). All members share conserved C-terminal catalytic domains that provide for lysyl oxidase or lysyl oxidase-like enzyme activity; and more divergent propeptide regions. LOX family enzyme activities catalyze the final enzymatic conversion required for the formation of normal biosynthetic collagen and elastin cross-links. The importance of lysyl oxidase enzyme activity to normal bone development has long been appreciated, but regulation and roles for specific LOX isoforms in bone formation in vivo is largely unexplored. Fracture healing recapitulates aspects of endochondral bone development. The present study first investigated the expression of all LOX isoforms in fracture healing. A remarkable coincidence of LOXL2 expression with the chondrogenic phase of fracture healing was found, prompting more detailed analyses of LOXL2 expression in normal growth plates, and LOXL2 expression and function in developing ATDC5 chondrogenic cells. Data show that LOXL2 is expressed by pre-hypertrophic and hypertrophic chondrocytes in vivo, and that LOXL2 expression is regulated in vitro as a function of chondrocyte differentiation. Moreover, LOXL2 knockdown studies in vitro show that LOXL2 expression is required for ATDC5 chondrocyte cell line differentiation through regulation of SNAIL and SOX9, important transcription factors that control chondrocyte differentiation. Taken together, data provide evidence that LOXL2, like LOX, is a multifunctional protein. LOXL2 promotes chondrocyte differentiation by mechanisms that are likely to include roles as both a regulator and an effector of chondrocyte differentiation.

Multipodal coordination of a tetracarboxylic crown ether with NH4(+): a vibrational spectroscopy and computational study.

The elucidation of the structural requirements for molecular recognition by the crown ether (18-crown-6)-2,3,11,12-tetracarboxylic acid (18c6H(4)) and its cationic complexes constitutes a topic of current fundamental and practical interest in catalysis and analytical sciences. The flexibility of the central ether ring and its four carboxyl side arms poses important challenges to experimental and theoretical approaches. In this study, infrared action vibrational spectroscopy and quantum mechanical computations are employed to characterize the conformational structure of the isolated gas phase complex formed by the 18c6H(4) host with NH(4)(+) as guest. The results show that the most stable gas-phase structure is a barrel-like conformation sustained by tetrapodal H-bonding of the ammonia cation with two C=O side groups and with four oxygen atoms of the ether ring in a bifurcated arrangement. Interestingly, a similar structure had been proposed in previous crystallographic studies. The experiment also provides evidence for a significant contribution of a higher energy bowl-like conformer with features resembling those adopted by 18c6H(4) in the analogous complexes with secondary amines. Such a conformation displays H-bonding between confronted side carboxyl groups and tetrapodal binding of the NH(4)(+) with the ether ring and with one C=O group. Structures involving even more extensive intramolecular H-bonding in the 18c6H(4) substrate are found to lie higher in energy and are ruled out by the experiment.

Association between preoperative serum lactate concentrate with tumor cell proliferative index in primary brain tumor.

BACKGROUND: Elevated preoperative lactate levels have been reported in patients admitted for resection of brain tumors. As histologic type and tumor grade have also been linked to lactate concentration, we hypothesized that preoperative lactate concentration in patients with brain tumors may be associated with tumor proliferation. We describe the relationship between preoperative plasma lactate levels, and the cell proliferation marker Ki-67 in brain tumor surgery. METHODS: In this cross-sectional study, records of patients who underwent craniotomy between June 2017 and February 2018 at our Hospital were reviewed to select glioma and meningioma cases in which lactate concentrations in plasma and degree of cell proliferation were registered. Bivariable and linear regression analyses were used to assess the association between lactate concentrations and the Ki-67 Index. RESULTS: Lactate concentrations in plasma and Ki-67 Index were available in 55 patients. Meningioma cases had a mean concentration of 1.2 (0.1) mmol/L compared to diffuse astrocytic and oligodendroglial tumors cases with 1.7 (0.1) mmol/L (P<0.01). Both variables had a low positive correlation in meningiomas (Spearman's r, 0.29; 95% CI, -0.10-0.61; P=0.13) and a high correlation in gliomas (Spearman's r, 0.64; 95% CI, 0.33-0.82; P<0.01). The pooled analysis showed a high correlation index (Spearman's r, 0.61; 95% CI, 0.40-0.76; P<0.01). A linear regression model showed that the Ki-67 Index explained 43% of the variation in lactate (P<0.01). CONCLUSIONS: Brain tumors with higher rates of cell proliferation have higher plasma lactate levels. In this scenario, lactate concentrations may not only reflect systemic perfusion.

Crown ether complexes with H3O⁺ and NH4⁺: proton localization and proton bridge formation.

The complexes formed by crown ethers with hydronium and ammonium cations are of key relevance for the understanding of their supramolecular behavior in protic solvents. In this work, the complexes of the 15-crown-5 (15c5) and 18-crown-6 (18c6) ethers with H3O⁺ and NH4⁺ and their deuterated variants are investigated under isolated conditions. The study employs infrared multiple photon dissociation (IRMPD) vibrational spectroscopy and DFT B3LYP/6-31++G(d,p) calculations for conformational assignment. The 18c6 ether provides two energetically nearby C(3v) conformations with commensurate linear O-H···O and N-H···O bonds. The 15c5 ether ring adopts partially folded asymmetric pyramidal geometries, yielding one shorter linear H bond and two longer non-linear H bonds. Remarkably, an appreciable broadening of the IRMPD vibrational bands is observed for the 15c5-H3O⁺/D3O⁺ complexes. This can be interpreted as a signature for partial sharing of the proton (or deuteron) between the water and the crown ether along the linear O-H···O intermolecular H bond, which is indeed particularly short for this complex.

Use of second generation supraglottic airway device for endovascular treatment of unruptured intracranial aneurysms: a retrospective cohort.

BACKGROUND: We aimed to assess the feasibility of using supraglottic devices as an alternative to orotracheal intubation for airway management during anesthesia for endovascular treatment of unruptured intracranial aneurisms in our department over a nine-year period. METHODS: Retrospective single center analysis of cases (2010-2018). Primary outcomes: airway management (supraglottic device repositioning, need for switch to orotracheal intubation, airway complications). SECONDARY OUTCOMES: aneurysm complexity, history of subarachnoid hemorrhage, hemodynamic monitoring, and perioperative complications. RESULTS: We included 187 patients in two groups: supraglottic device 130 (69.5%) and orotracheal intubation 57 (30.5%). No adverse incidents were recorded in 97% of the cases. Three supraglottic device patients required supraglottic device repositioning and 1 supraglottic device patient required orotracheal intubation due to inadequate ventilation. Three orotracheal intubation patients had a bronchospasm or laryngospasm during awakening. Forty-five patients (24.1%) had complex aneurysms or a history of subarachnoid hemorrhage. Thirty-three of them (73.3%) required orotracheal intubation compared to 24 of the 142 (16.9%) with non-complex aneurysms. Two patients in each group died during early postoperative recovery. Two in each group also had intraoperative bleeding. A post-hoc analysis showed that orotracheal intubation was used in 55 patients (44%) in 2010 through 2014 and 2 (3.2%) in 2015 through 2018, parallel to a trend toward less invasive blood pressure monitoring from the earlier to the later period from 34 (27.2%) cases to 5 (8.2%). CONCLUSION: Supraglottic device, like other less invasiveness protocols, can be considered a feasible alternative airway management approach in selected patients proposed for endovascular treatment of unruptured intracranial aneurisms.

Hemodynamic Response, Coughing and Incidence of Cerebrospinal Fluid Leakage on Awakening with an Endotracheal Tube or Laryngeal Mask Airway in Place after Transsphenoidal Pituitary Surgery: A Randomized Clinical Trial.

We aimed to compare systemic and cerebral hemodynamics and coughing during emergence after pituitary surgery after endotracheal tube (ETT) extubation or after replacing ETT with a laryngeal mask airway (LMA). Patients were randomized to awaken with an ETT in place or after replacing it with an LMA. We recorded mean arterial pressure (MAP), heart rate, middle cerebral artery (MCA) flow velocity, regional cerebral oxygen saturation (SrO2), cardiac index, plasma norepinephrine, need for vasoactive drugs, coughing during emergence, and postoperative cerebrospinal fluid (CSF) leakage. The primary endpoint was postoperative MAP; secondary endpoints were SrO2 and coughing incidence. Forty-five patients were included. MAP was lower during emergence than at baseline in both groups. There were no significant between-group differences in blood pressure, nor in the number of patients that required antihypertensive drugs during emergence (ETT: 8 patients (34.8%) vs. LMA: 3 patients (14.3%); p = 0.116). MCA flow velocity was higher in the ETT group (e.g., mean (95% CI) at 15 min, 103.2 (96.3-110.1) vs. 89.6 (82.6-96.5) cm·s-1; p = 0.003). SrO2, cardiac index, and norepinephrine levels were similar. Coughing was more frequent in the ETT group (81% vs. 15%; p < 0.001). CSF leakage occurred in three patients (13%) in the ETT group. Placing an LMA before removing an ETT during emergence after pituitary surgery favors a safer cerebral hemodynamic profile and reduces coughing. This strategy may lower the risk for CSF leakage.

Gas-phase complexes of cyclic and linear polyethers with alkali cations.

The flexibility of polymer backbones constitutes one key aspect in their molecular recognition properties. This investigation characterizes the structure of the gas-phase complexes formed by the cyclic and linear polyethers with the heavier alkali metal cations. In particular, the cyclic 15-crown-5 ether (15c5), (OCH(2)CH(2))(5), and the polyethylene glycol linear chains PEG4 and PEG9, H(OCH(2)CH(2))(n=4,9)OH, are considered. Infrared multiple photon dissociation spectroscopy is applied to probe the polymer vibrational modes within the spectral range 800-1500 cm(-1), in combination with Density Functional Theory calculations. The experimental spectra of the 15c5-M(+) (M = K, Rb, Cs) complexes correlate with distorted asymmetric backbone structures in which the cation lies above the ether ring, and four oxygens are oriented toward the cation. In contrast, the PEG4-K(+) complex features an inclusion-like fivefold coordination structure in which the cation and four oxygens are quasi-coplanar and one terminal oxygen lies out of plane. For the PEG9-K(+) complex, the ether chain builds stable cages involving a coordination of eight oxygens with the cation, sustained by hydrogen bonds between the terminal hydroxyl groups.

Emergence of symmetry and chirality in crown ether complexes with alkali metal cations.

Crown ethers provide a valuable benchmark for the comprehension of molecular recognition mediated by inclusion complexes. One of the most relevant crown ethers, 18-crown-6 (18c6), features a flexible six-oxygen cyclic backbone that is well-known for its selective cation binding. This study employs infrared spectroscopy and quantum mechanical calculations to elucidate the structure of the gas-phase complexes formed by the 18c6 ether with the alkali metal cations. It is shown that symmetric and chiral arrangements play a dominant role in the conformational landscape of the 18c6-alkali system. Most stable 18c6-M(+) conformers are found to have symmetries C(3v) and C(2) for Cs(+), D(3d) for K(+), C(1) and D(3d) for Na(+), and D(2) for Li(+). Remarkably, whereas the bare 18c6 ether is achiral, chirality emerges in the C(2) and D(2) 18c6-M(+) conformations, both of which involve pairs of stable atropoisomers capable of acting as enantiomeric selective substrates.

Rescue Surgery in the Flow Diverter Era: Partial Trapping Plus Revascularization Technique for a Giant Carotid-Ophthalmic Aneurysm.

BACKGROUND: Flow diverters (FDs) are an excellent option for the management of giant carotid artery aneurysms. However, in a nonnegligible percent of cases, the aneurysm may continue to grow despite multiple endovascular treatments and apparent occlusion on the angiogram. Due to the recent introduction of FDs, surgical experience after their failure is scarce and neurosurgeons have to face these challenging cases without much previous reference. Here we describe a giant ophthalmic-carotid aneurysm that presented with new severe mass effect 5 years after initially successful treatment with FDs and coils. We investigate the likely advantages of partial trapping versus complete trapping in this particular type of case. CASE DESCRIPTION: A 63-year-old patient with a subarachnoid hemorrhage from a 26-mm left carotid-ophthalmic aneurysm was initially embolized with coils. One year later a recanalization was observed and treated with an FD. Five years afterward, the patient's mild cognitive impairment prompted a magnetic resonance image that showed significant aneurysm growth despite apparent occlusion on angiogram. Rescue surgery consisted of partial trapping + extracranial-intracranial bypass and aneurysm debulking. The patient recovered from his deficits and remains asymptomatic 2 years later. CONCLUSIONS: In selected patients with previous long-term FDs, partial trapping may be a choice even if aneurysm debulking is needed. After years of stent placement, some endothelialization and neointimal membrane formation could have a summing effect to facilitate surgical exclusion and enable a safe thrombectomy. Classic revascularization techniques must be rethought and retested in this new FD era scenario.

Spectroscopic investigation of the gas-phase conformations of 15-crown-5 ether complexes with K+.

Infrared multiple photon dissociation action spectra of the binary and ternary gas-phase complexes formed by 15-crown-5 ether with potassium cations (15c5-K(+) and 15c5-K(+)-15c5) are reported. The spectra span the 800-1500 cm(-1) infrared range. Particularly significant differences are found in the position and structure of the CO-stretching band of the two types of complexes. The computational prediction at the DFT-B3LYP/6-31G* level of theory agrees well with the experimental observations, and provides a correlation between the spectral differences and the structural changes associated with the coordination of the ether oxygens with the alkali cation. The 15c5-K(+) complex adopts a pyramidal structure, with the cation lying above the center of mass of the ether ring at a distance similar to its ionic radius. The ternary 15c5-K(+)-15c5 complex features a less tight coordination of the cation and a relative rotation between the backbones of the two crown ethers, which minimizes the intermolecular repulsions between the oxygens.

The influence of arm abduction on the anatomic relations of infraclavicular brachial plexus: an ultrasound study.

BACKGROUND: Distances from brachial plexus to the coracoid process and the pleura are critical for performing infraclavicular block. We evaluated the influence of arm abduction on the position of the neurovascular bundle relative to the skin, to the coracoid process and to the pleura using ultrasonography. METHODS: An ultrasound examination of the brachial plexus at the infraclavicular level was performed on 26 patients. Distances from the axillary artery to the skin, to the coracoid process and to the pleura were measured and noted with different degrees of arm abduction (0 degrees , 45 degrees , and 90 degrees ). Vertical infraclavicular brachial plexus block was then performed by means of nerve stimulation in 14 additional patients undergoing hand surgery. RESULTS: Under ultrasound examination, the distance from the axillary artery to the skin was found to be significantly less with arm abduction (0 degrees : 32 +/- 7 mm, 45 degrees : 29 +/- 7 mm, 90 degrees : 25 +/- 5 mm, P < 0.05). The distance from the skin to the pleura was 47 +/- 5 mm with a medial deviation of 18 +/- 3 degrees and was not influenced by arm position. Brachial plexus was identified by nerve stimulation at a vertical depth of 41 +/- 7 mm from the skin. CONCLUSION: Abduction of the arm reduces the depth of the brachial plexus but does not change the position of the axillary artery relative to the coracoid process or the pleura. Ultrasonography may under-estimate the actual depth of the plexus.

Lysyl oxidase propeptide inhibits smooth muscle cell signaling and proliferation.

Lysyl oxidase is required for the normal biosynthesis and maturation of collagen and elastin. It is expressed by vascular smooth muscle cells, and its increased expression has been previously found in atherosclerosis and in models of balloon angioplasty. The lysyl oxidase propeptide (LOX-PP) has more recently been found to have biological activity as a tumor suppressor, and it inhibits Erk1/2 Map kinase activation. We reasoned that LOX-PP may have functions in normal non-transformed cells. We, therefore, investigated its effects on smooth muscle cells, focusing on important biological processes mediated by Erk1/2-dependent signaling pathways including proliferation and matrix metalloproteinase-9 (MMP-9) expression. In addition, we investigated whether evidence for accumulation of LOX-PP could be found in vivo in a femoral artery injury model. Recombinant LOX-PP was expressed and purified, and was found to inhibit primary rat aorta smooth muscle cell proliferation and DNA synthesis by more than 50%. TNF-alpha-stimulated MMP-9 expression and Erk1/2 activation were both significantly inhibited by LOX-PP. Immunohistochemistry studies carried out with affinity purified anti-LOX-PP antibody showed that LOX-PP epitopes were expressed at elevated levels in vascular lesions of injured arteries. These novel data suggest that LOX-PP may provide a feedback control mechanism that serves to inhibit properties associated with the development of vascular pathology.

Solvent-free MALDI investigation of the cationization of linear polyethers with alkali metals.

The MALDI technique with solvent-free sample preparation has been applied to evaluate relative gas-phase affinities of polyether chain polymers with alkali metal cations. The study is performed on poly(ethylene glycol) and poly(propylene glycol) polymers of different lengths (PEG600, PEG1000, PPG425, PPG750) and the alkali metal cations Li(+), Na(+), K(+), and Cs(+). The experiments show that the lattice energy of the alkali metal salts employed as cation precursors can have a strong influence on the outcome of conventional MALDI measurements. With the solvent-free method, these crystal binding effects can be made negligible by combining in the same sample alkali metal salts with different counterions. The recorded MALDI spectra show that the polyether-cation aggregation efficiencies decrease systematically with growing cation size. This cation size selectivity is considerably enhanced for the polymers with the shorter chains, which can be attributed to the reduced ability of the polymer to build a coordination shell around the larger cations. The steric effects introduced by the side CH3 group of propylene glycol with respect to ethylene glycol also enhance the preference for cationization of the polymer by the smaller cations. These observations correct some qualitative trends derived from previous studies, which did not account for lattice energy effects of the cation precursors.