Developmental expression of the TTX-resistant voltage-gated sodium channels Nav1.8 (SNS) and Nav1.9 (SNS2) in primary sensory neurons.

The development of neuronal excitability involves the coordinated expression of different voltage-gated ion channels. We have characterized the expression of two sensory neuron-specific tetrodotoxin-resistant sodium channel alpha subunits, Na(v)1. (SNS/PN3) and Na(v)1.9 (SNS2/NaN), in developing rat lumbar dorsal root ganglia (DRGs). Expression of both Na(v)1.8 and Na(v)1.9 increases with age, beginning at embryonic day (E) 15 and E17, respectively, and reaching adult levels by postnatal day 7. Their distribution is restricted mainly to those subpopulations of primary sensory neurons in developing and adult DRGs that give rise to unmyelinated C-fibers (neurofilament 200 negative). Na(v)1.8 is expressed in a higher proportion of neuronal profiles than Na(v)1.9 at all stages during development, as in the adult. At E17, almost all Na(v)1.8-expressing neurons also express the high-affinity NGF receptor TrkA, and only a small proportion bind to IB4, a marker for c-ret-expressing (glial-derived neurotrophic factor-responsive) neurons. Because IB4 binding neurons differentiate from TrkA neurons in the postnatal period, the proportion of Na(v)1.8 cells that bind to IB4 increases, in parallel with a decrease in the proportion of Na(v)1.8-TrkA co-expressing cells. In contrast, an equal number of Na(v)1.9 cells bind IB4 and TrkA in embryonic life. The differential expression of Na(v)1.8 and Na(v)1.9 in late embryonic development, with their distinctive kinetic properties, may contribute to the development of spontaneous and stimulus-evoked excitability in small diameter primary sensory neurons in the perinatal period and the activity-dependent changes in differentiation they produce.

A role for HSP27 in sensory neuron survival.

Peripheral nerve injury in neonatal rats results in the death of the majority of the axotomized sensory neurons by 7 d after injury. In adult animals, however, all sensory neurons survive for at least 4 months after axotomy. How sensory neurons acquire the capacity to survive axonal injury is not known. Here we describe how the expression of the small heat shock protein 27 (HSP27) is correlated with neuronal survival after axotomy in vivo and after NGF withdrawal in vitro. The number of HSP27-immunoreactive neurons in the L4 DRG is low at birth and does not change significantly for 21 d after postnatal day 0 (P0) sciatic nerve axotomy. In contrast, in the adult all axotomized neurons begin to express HSP27. One week after P0 sciatic nerve section the total number of neurons in the L4 DRG is dramatically reduced, but all surviving axotomized neurons, as identified by c-jun immunoreactivity, are immunoreactive for HSP27. In addition, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling reveals that very few HSP27-expressing neurons are dying 48 hr after neonatal axotomy. In vitro, a similar correlation exists between HSP27 expression and survival; in P0 DRG cultures, neurons that express HSP27 preferentially survive NGF withdrawal. Finally, overexpression of human HSP27 in neonatal rat sensory and sympathetic neurons significantly increases survival after NGF withdrawal, with nearly twice as many neurons surviving at 48 hr. Together these results suggest that HSP27 in sensory neurons plays a role in promoting survival after axotomy or neurotrophin withdrawal.

Identification and characterization of a novel human vanilloid receptor-like protein, VRL-2.

Remarkable progress has been made recently in identifying a new gene family related to the capsaicin (vanilloid) receptor, VR1. Using a combination of in silico analysis of expressed sequence tag (EST) databases and conventional molecular cloning, we have isolated a novel vanilloid-like receptor, which we call VRL-2, from human kidney. The translated gene shares 46% and 43% identity with VR1 and VRL-1, respectively, and maps to chromosome 12q23-24.1, a locus associated with bipolar affective disorder. VRL-2 mRNA was most strongly expressed in the trachea, kidney, and salivary gland. An affinity-purified antibody against a peptide incorporating the COOH terminal of the receptor localized VRL-2 immunolabel in the distal tubules of the kidney, the epithelial linings of both trachea and lung airways, serous cells of submucosal glands, and mononuclear cells. Unlike VR1 and VRL-1, VRL-2 was not detected in cell bodies of dorsal root ganglia (DRG) or sensory nerve fibers. However, VRL-2 was found on sympathetic and parasympathetic nerve fibers, such as those innervating the arrector pili smooth muscle in skin, sweat glands, intestine, and blood vessels. At least four vanilloid receptor-like genes exist, the newest member, VRL-2 is found in airway and kidney epithelia and in the autonomic nervous system.

Lateralized use of the mouth in production of vocalizations by marmosets.

We have found that the common marmoset, Callithrix jacchus, displays a larger left hemimouth during production of fear expressions, with or without vocalization, and a larger right hemimouth when producing a social contact call. Thus, marmosets have right hemisphere specialization for the production of negative emotional expressions and vocalizations and left hemisphere specialization for the production of social contact communication. These hemispheric specializations for social communication in marmosets are the same as those found in humans for speech production and for the control of emotional expressions. We suggest that hemispheric specializations for communication in humans may well have precursors in primate evolution.

Systemic inflammatory response syndrome, sepsis, severe sepsis and septic shock: incidence, morbidities and outcomes in surgical ICU patients.

OBJECTIVES: To determine the incidence of systemic inflammatory response syndrome (SIRS), sepsis and severe sepsis in surgical ICU patients and define patient characteristics associated with their acquisition and outcome. DESIGN: One-month prospective study of critically ill patients with a 28 day in-hospital follow up. SETTING: Surgical intensive care unit (SICU) at a tertiary care institution. METHODS: All patients (n = 170) admitted to the SICU between April 1 and April 30, 1992 were prospectively followed for 28 days. Daily surveillance was performed by two dedicated, specifically-trained research nurses. Medical and nursing chart reviews were performed, and follow up information at six and twelve months was obtained. RESULTS: The in-hospital surveillance represented 2246 patient-days, including 658 ICU patient-days. Overall, 158 patients (93%) had SIRS for an incidence of 542 episodes/1000 patients-days. The incidence of SIRS in the ICU was even higher (840 episodes/1000 patients-days). A total of 83 patients (49%) had sepsis; among them 28 developed severe sepsis. Importantly, 13 patients had severe sepsis after discharge from the ICU. Patient groups were comparable with respect to age, sex ratio, and type of surgery performed. Apache II score on admission to the ICU and ASA score at time of surgery were significantly higher (p < 0.05) only for patients who subsequently developed severe sepsis. The crude mortality at 28 days was 8.2% (14/170); it markedly differed among patient groups: 6% for those with SIRS vs. 35% for patients with severe sepsis. Patients with sepsis and severe sepsis had a longer mean length of ICU stay (2.1 +/- 0.2 and 7.5 +/- 1.5, respectively) than those with SIRS (1.45 +/- 0.1) or control patients (1.16 +/- 0.1). Total length of hospital stay also markedly differed among groups (35 +/- 9 (severe sepsis), 24 +/- 2 (sepsis), 11 +/- 0.8 (SIRS), and 9 +/- 0.1 (controls, respectively). CONCLUSIONS: Almost everyone in the SICU had SIRS. Therefore, because of its poor specificity, SIRS was not helpful predicting severe sepsis and septic shock. Patients who developed sepsis or severe sepsis had higher crude mortality and length of stay than those who did not. Studies designed to identify those who develop complications of SIRS would be very useful.

Pain: molecular mechanisms.

Our understanding of chronic inflammatory and neuropathic pain at the molecular and cellular level has developed at an extraordinary rate in recent years. Inflammatory, or neuropathic, neuronal plasticity describes the process by which the neurons involved in pain transmission are converted from a state of normosensitivity to one in which they are hypersensitive. Here we summarize current theories on somatosensory neuroplasticity in a molecular context, highlighting key receptors, ion channels, and signal molecules involved. We also suggest new possibilities for drug design, based on the rational targeting of these molecular players.

Origin and significance of urinary N-acetyl-beta, D-glucosaminidase (NAG) in renal patients with proteinuria.

In patients with proteinuria, indices of tubular damage are unreliable since filtered plasma enzymes could contribute to tubular enzymuria. Previous work has suggested the existence of various forms of the 'A' isoenzyme of N-acetyl-beta, D-glucosaminidase (NAG), one of which could be kidney specific and thus a useful marker of renal tubular damage. By using fast protein liquid chromatography, two forms of the 'A' isoenzyme, 'A1' and 'A2' were separated in human urine, plasma and kidney tissue. The isoenzyme profile in pathological urine resembled that seen in kidney tissue, the 'A2' isoenzyme predominating. The ratio A2/A1 in the urine of renal patients was significantly greater than in the plasma of renal patients, end-stage renal failure patients and healthy volunteers. There was no difference in the plasma ratios of the three groups studied. The clearances of total NAG, 'A1' and 'A2' isoenzymes were all greater than that of the lower molecular weight protein transferrin. This indicates that the origin of urinary NAG in patients with proteinuria is from the kidney itself. Thus, analysis of urinary NAG and its isoenzymes may be of benefit as an early predictor of renal tubular damage and may also be useful as a non-invasive indicator of disease progression.

Synthesis and physicochemical properties of the furan dicarboxylic acid, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid, an inhibitor of plasma protein binding in uraemia.

The furan dicarboxylic acid, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (5-propyl FPA) accumulates in the plasma of patients with chronic renal failure and is a major contributor to the drug binding defect of uraemic plasma. This acid has also been implicated in several other aspects of the uraemic syndrome: anaemia, irregularities of thyroid function, neurological symptoms and inhibition of active tubular secretion. The acid is not commercially available and its synthesis, starting with Meldrum's acid and methyl succinyl chloride, is described. The pKa values were measured by titration and values of 3.2 and 3.6 respectively were assigned to the carboxylic acid groups attached directly to the ring at position 3 and at position 2 (on the side-chain). The partition coefficient (log P) between hydrochloric acid and octanol was 1.2 and the distribution coefficient (log D; octanol-phosphate buffer pH 7.4) was -0.59. The pKa values and the degree of hydrophobic character of 5-propyl FPA are consistent with those of other protein-bound acids which undergo active tubular secretion by the kidney and this substance may serve as an endogenous marker for the effects of drugs and disease on this process.

The use of the edema bar for the treatment of burn patients.

The edema bar is a new device that therapists can add to their repertoire of treatment approaches for burn patients. This article looks at the challenges therapists encounter while working with burn patients and describes the edema bar's design, its application to the burn rehabilitation process, and the multidisciplinary approach to its use.

Plasma clearance in the rat of a furan dicarboxylic acid which accumulates in uremia.

The furan dicarboxylic acid 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (5-propyl FPA) accumulates in the plasma of patients with chronic renal failure and has been implicated in several aspects of the uremic syndrome: the defective binding of organic acids in uremic plasma, inhibition of active tubular secretion, anemia and the severity of neurological symptoms. Evidence from experiments with rat kidney slices suggests that 5-propyl FPA undergoes active tubular secretion, and so its clearance after an intravenous bolus dose (5 mg/kg; 21 mumol/kg) was investigated in anaesthetized female Wistar albino rats in vivo. The effects of intravenous bolus doses of p-aminohippuric acid (PAH) and probenecid on the clearance of this dose of 5-propyl FPA were also studied. The mean values (N = 16) for plasma half-life, plasma clearance and apparent volume of distribution of 5-propyl FPA were 3.6 hours, 2.4 ml . min(-1) . kg(-1) and 0.69 liter . kg(-1), respectively. An equimolar dose of PAH did not affect the clearance of 5-propyl FPA, but a tenfold higher molar dose of PAH (40.4 mg/kg) increased the area under the plasma-concentration time curve of 5-propyl FPA, and there was a trend towards a decrease in the clearance and a prolongation of the half-life. Probenecid at a fivefold higher dose than 5-propyl FPA had a similar effect to PAH and increased the AUC of 5-propyl FPA. PAH and probenecid decreased the plasma clearance of 5-propyl FPA, which is evidence that this uremic metabolite undergoes active tubular secretion. It follows that 5-propyl FPA could therefore inhibit the secretion of other organic acids.

Transcriptional and posttranslational plasticity and the generation of inflammatory pain.

Inflammatory pain manifests as spontaneous pain and pain hypersensitivity. Spontaneous pain reflects direct activation of specific receptors on nociceptor terminals by inflammatory mediators. Pain hypersensitivity is the consequence of early posttranslational changes, both in the peripheral terminals of the nociceptor and in dorsal horn neurons, as well as later transcription-dependent changes in effector genes, again in primary sensory and dorsal horn neurons. This inflammatory neuroplasticity is the consequence of a combination of activity-dependent changes in the neurons and specific signal molecules initiating particular signal-transduction pathways. These pathways phosphorylate membrane proteins, changing their function, and activate transcription factors, altering gene expression. Two distinct aspects of sensory neuron function are changed as a result of these processes, basal sensitivity, or the capacity of peripheral stimuli to evoke pain, and stimulus-evoked hypersensitivity, the capacity of certain inputs to generate prolonged alterations in the sensitivity of the system. Posttranslational changes largely alter basal sensitivity. Transcriptional changes both potentiate the system and alter neuronal phenotype. Potentiation occurs as a result of the up-regulation in the dorsal root ganglion of centrally acting neuromodulators and simultaneously in the dorsal horn of their receptors. This means that the response to subsequent inputs is augmented, particularly those that induce stimulus-induced hypersensitivity. Alterations in phenotype includes the acquisition by A fibers of neurochemical features typical of C fibers, enabling these fibers to induce stimulus-evoked hypersensitivity, something only C fiber inputs normally can do. Elucidation of the molecular mechanisms responsible provides new opportunities for therapeutic approaches to managing inflammatory pain.

Hypothesis: is accumulation of a furan dicarboxylic acid (3-carboxy-4- methyl-5-propyl-2-furanpropanoic acid) related to the neurological abnormalities in patients with renal failure?

The Plasma concentrations of a lipophilic furan dicarboxylic acid (3- carboxy-4-methyl-5-propyl-2-fluranpropanoic acid; 5-propyl FPA), which is highly bound to albumin and not removed by haemodialysis, have been measured in patients with renal impairment who were not dialysis dependent or who were treated by either haemodialysis or peritoneal dialysis. Neurological abnormalities were assessed as absent, moderate, or severe. A relationship was observed between the increasing severity of abnormalities attributable to the uraemic state and the higher plasma concentrations of 5-propyl FPA. There are theoretical grounds for believing that 5-propyl FPA contributes to these neurological abnormalities because of its structure and also because it inhibits the transport of organic acids in the kidney and could do likewise at the blood-brain barrier.

Retention of an albumin-bound furan dicarboxylic acid in patients with chronic renal failure or after a kidney transplant.

BACKGROUND: 3-Carboxy-4-methyl-5-propyl-2-furanpropanoic acid (5-propyl FPA) is a furan dicarboxylic acid which accumulates in the plasma of patients with renal impairment. 5-Propyl FPA is an inhibitor of the binding of drugs to albumin and is also implicated in other aspects of the uraemic syndrome. METHODS: Plasma concentrations of propyl FPA have been measured in non-dialysis-dependent, chronic renal failure patients and in renal transplant patients by high-performance liquid chromatography. Concentrations of haemoglobin, albumin and creatinine were also determined. RESULTS: There was a positive correlation between serum creatinine and 5-propyl FPA and a negative correlation between haemoglobin concentration and 5-propyl FPA in chronic renal failure patients. There was a negative correlation between 5-propyl FPA and duration of transplant only when the serum creatinine was >200 microM. The mean plasma concentration of 5-propyl FPA in chronic renal failure patients with plasma creatinine CONCLUSIONS: This retention of 5-propyl FPA may therefore reflect a specific tubular defect in renal transplant patients treated with cyclosporin and points to the possibility that 5-propyl FPA may serve as a marker of tubular dysfunction.

Effects of haemodialysis and continuous ambulatory peritoneal dialysis on the plasma clearance of an albumin-bound furan dicarboxylic acid.

Organic acids that are strongly bound to albumin are not removed by dialysis and the plasma concentrations of one such substance, a furan dicarboxylic acid (3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid: 5-propyl FPA) have been measured by HPLC in healthy subjects (n = 21), patients on regular haemodialysis (n = 30), and patients treated by continuous ambulatory peritoneal dialysis (n = 21). The mean (+/- SD) concentrations of 5-propyl FPA were significantly higher in haemodialysis (95 +/- 44 microM) compared to CAPD patients (28 +/- 19 microM) and both were higher than in healthy individuals (14 +/- 7 microM). Haemoglobin concentrations in CAPD patients were significantly higher than in those on haemodialysis while these patients had significantly higher albumin concentrations than CAPD patients. The concentration of 5-propyl FPA was positively correlated with the duration of dialysis for haemodialysis patients but not for CAPD patients. The lower concentrations of 5-propyl FPA in CAPD patients may at least partly explain the higher haemoglobin levels found in these patients.

Proteinuria and renal tubular damage: urinary N-acetyl-beta-D-glucosaminidase and isoenzymes in dissimilar renal disease.

Markers of renal tubular injury are difficult to interpret in patients with proteinura. The 24-hour urinary N-acetyl-beta-D-glucosaminidase (NAG) concentration was measured in 167 patients with dissimilar renal disease, function, and proteinuria. NAG isoenzymes were also separated in 69 patients, using a modified fast protein liquid chromatography technique. The 'A2' isoenzyme predominated at all levels of renal function and in all diagnostic groups. Urinary NAG and proteinuria were well correlated at all levels of renal function, as was NAG 'A2' isoenzyme. Proteinuria and urinary NAG were similarly correlated in patients with different glomerulonephritides, hypertensive nephrosclerosis, and chronic pyelonephritis, but not in those with diabetic nephropathy.

Staphylococcus aureus bacteremia: the cost-effectiveness of long-term therapy associated with infectious diseases consultation.

OBJECTIVE: To investigate the cost-effectiveness of long-term therapy for Staphylococcus aureus bacteremia and to determine if an infectious diseases consultation affected the duration of therapy. METHODS: A decision analysis was performed based on data from the literature. To determine if consultation was related to therapy duration, a retrospective cohort study was performed using tightly matched pairs. RESULTS: The excess cost per life saved by long-term antibiotics was $500,000. The excess cost per life-year saved was $18,000. Nine pairs were matched. Patients who received consultation were more likely to receive long-term therapy than controls (median 41 days vs 15 days for controls, P = .04). CONCLUSIONS: The estimated cost per life-year saved by long-term therapy was similar to other accepted medical interventions. Infectious diseases consultation can encourage prolonged duration of antibiotic therapy for S aureus bacteremia.

Eye preferences in common marmosets (Callithrix jacchus): influence of age, stimulus, and hand preference.

Eye preferences of the common marmoset ( Callithrix jacchus ) were examined, taking into account age, arousal, and hand preference. Monocular eye use for looking through a small hole at a stimulus was recorded. Of 21 marmosets, 20 displayed right-eye preferences for viewing a piece of familiar food. In subjects tested at 3-8, 12, 15-18, and 22 months, eye preferences were consistent across age. A group bias, indicative of right-eyedness, was also found for viewing other stimuli. The stimuli included a watch, mirror, model of a beetle, and the experimenter's hand. However, when the marmosets viewed a threatening stimulus, a model resembling two rearing snakes, they displayed increased arousal (indicated by longer duration between monocular viewing events and increased incidence of aroused vocalisations) and the eye preferences shifted away from a preference for the right eye to either no preference or a left-eye preference. No relationship between eye preference and hand preference for holding food was found. Therefore, we suggest that eye preferences may reflect hemispheric specialisations for perceptual processing, according to the emotional valence of the stimulus.

Hand, mouth and eye preferences in the common marmoset (Callithrix jacchus).

Motor and sensory preferences were measured for 8 common marmosets (Callithrix jacchus). Three types of motor function were examined: spontaneous feeding, mouth use when chewing and visuospatial reaching. Eye preference was used as an index of sensory lateralization. The marmosets displayed individual preferences for the performance of the motor tasks, but no group biases were revealed. Correlations between preferences displayed on the motor tests suggest that one hemisphere may control spontaneous feeding and lateralized mouth use while the other controls visuospatial reaching, but no consistent preference was present. In an eye preference test, 7 subjects displayed right-eye preferences, suggesting hemispheric specialisation for this function.