Synchronized paroxysmal activity in the developing thalamocortical network mediated by corticothalamic projections and "silent" synapses.

In mouse thalamocortical slices in vitro, the potassium channel blocker 4-AP and GABAA receptor antagonist bicuculline together induced spontaneous prolonged depolarizations in layer VI neurons from postnatal day 2 (P2), in ventroposterior nucleus neurons (VP) from P7, and in reticular nucleus neurons (RTN) from P8. Dual whole-cell recordings revealed that prolonged bursts were synchronized in layer VI, VP, and RTN. Bursts were present in cortex isolated from thalamus, but not in thalamus isolated from cortex, indicating that bursts originated in cortex and propagated to thalamus. Prolonged bursts were synchronized in layer VI when vertical cuts extended from pia mater through layers IV or V, but were no longer synchronized when cuts extended through layer VI and white matter. In voltage-clamp recordings before P10, burst conductance of all three neuronal populations was dominated by the NMDA receptor-mediated conductance, and therefore synapses were "silent". In cortex and RTN, after P10, bursts were associated with strong AMPA/kainate receptor-mediated conductances, and synapses had become "functional"; silent synapses persisted in a large proportion of VP cells after P10. Before P9, the NMDA receptor antagonist APV or the non-NMDA receptor antagonist CNQX blocked the prolonged bursts. After P9, CNQX continued to block the prolonged bursts, but APV merely shortened their duration. Thus, NMDA receptor-based silent synapses are essential for paroxysmal corticothalamic activity during early postnatal development, and connections between layer VI neurons are sufficient for horizontal cortical synchronization.     

Differential c-Fos expression in cholinergic, monoaminergic, and GABAergic cell groups of the pontomesencephalic tegmentum after paradoxical sleep deprivation and recovery.

Multiple lines of evidence indicate that neurons within the pontomesencephalic tegmentum are critically involved in the generation of paradoxical sleep (PS). From single-unit recording studies, evidence suggests that unidentified but "possibly" cholinergic tegmental neurons discharge at higher rates during PS than during slow wave sleep or even waking and would thus play an active role, whereas "presumed" monoaminergic neurons cease firing during PS and would thus play a permissive role in PS generation. In the present study performed on rats, c-Fos immunostaining was used as a reflection of neuronal activity and combined with immunostaining for choline acetyltransferase (ChAT), serotonin (Ser), tyrosine hydroxylase (TH), or glutamic acid decarboxylase (GAD) for immunohistochemical identification of active neurons during PS recovery ( approximately 28% of recording time) as compared with PS deprivation (0%) and PS control (approximately 15%) conditions. With PS recovery, there was a significant increase in ChAT+/c-Fos+ cells, a significant decrease in Ser+/c-Fos+ and TH+/c-Fos+ cells, and a significant increase in GAD+/c-Fos+ cells. Across conditions, the percent PS was correlated positively with tegmental cholinergic c-Fos+ cells, negatively with raphe serotonergic and locus coeruleus noradrenergic c-Fos+ cells, and positively with codistributed and neighboring GABAergic c-Fos+ cells. These results support the hypothesis that cholinergic neurons are active, whereas monoaminergic neurons are inactive during PS. They moreover indicate that GABAergic neurons are active during PS and could thus be responsible for inhibiting neighboring monoaminergic neurons that may be essential in the generation of PS.     

Would you take blood through a venflon?

One way of saving junior doctors' time and patients' pain is to take blood samples through a venflon immediately after its insertion. This is not, however, universal practise as some believe the results, especially urea and electrolytes, are unreliable. We have surveyed junior doctors in our hospital about this practise and prospectively compared venflon and vein blood samples.     

The Mineralization Density of Iliac Crest Bone from Children with Osteogenesis Imperfecta

We studied iliac crest biopsy cores taken from young individuals with osteogenesis imperfecta of several types, and from age-matched normals; the same samples had been used in prior studies using conventional light microscopic histomorphometric procedures. The PMMA blocks were micro-milled to a fine finish, carbon coated, and imaged using backscattered electrons (BSE) in an automated digital scanning electron microscope (SEM). For comparison of BSE signal levels between samples, microscope operation parameters were standardized by reference to halogenated dimethacrylate standards, and recording data from stereological arrays of 512*512 nonoverlapping pixels at 3.5 μm separation. All OI types showed higher average mineralization densities than age- and site-matched normals. This is interpreted as the result of the failure in matrix assembly, such that it has a higher water volume fraction available for mineral deposition. Added to the net deficit in bone quantity, the predicted higher stiffness of the more mineralized bone will account for much of the observed `brittleness' that characterizes this class of genetic disease. The mean mineralization density, which was higher in types III, IV, and V than in type I, appears to be correlated with disease severity. Received: 5 January 1998 / Accepted: 7 August 1998     

Lack of effect of combined low intensity laser therapy/phototherapy (CLILT) on delayed onset muscle soreness in humans

BACKGROUND AND OBJECTIVES: This study, which was approved by the University's Ethical committee, was conducted to investigate the effectiveness of Combined Low Intensity Laser Therapy/Phototherapy (CLILT) in alleviating the signs and symptoms of Delayed Onset Muscle Soreness (DOMS) over an 11-day period. STUDY DESIGN/MATERIALS AND METHODS: Thirty-six subjects (18 M: 18 F) were randomly allocated, under strictly controlled double-blind conditions, to one of three experimental conditions: Control, Placebo, and CLILT (660-950 nm; 11 J/cm2; pulsed at 73 Hz). DOMS was induced in a standardised fashion in the non-dominant elbow flexors using repeated eccentric contractions until exhaustion was reached. Subjects returned on five consecutive days, and two days during the following week, for treatment according to group, and assessment of outcome variables including range of motion, pain, and tenderness. RESULTS: While analysis of results using repeated measures and one factor ANOVA with post-hoc tests showed significant changes in all variables over time (P < 0.05) as a result of the induction procedure, there were no significant differences observed between groups. CONCLUSIONS: CLILT failed to show any beneficial treatment effect on DOMS, at least at the parameters used here. These results therefore provide no evidence for the claimed biostimulating effects of such therapy.     

Intermediate-term outcome of primary digit amputations in patients with diabetes mellitus who have forefoot sepsis requiring hospitalization and presumed adequate circulatory status.

PURPOSE: The intermediate success and outcome of primary forefoot amputations in patients with diabetes mellitus who have sepsis limited to the forefoot and presumed adequate forefoot perfusion, as determined by means of noninvasive methods, was studied. METHODS: Cases of a university hospital-based practice from January 1984 to April 1998 were retrospectively reviewed. Patients included had diabetes mellitus with forefoot sepsis requiring immediate hospitalization for digit amputations who had adequate arterial circulation for healing based on noninvasive and clinical assessment: palpable pedal pulses (29%), "compressible" ankle pressure of 70 mm Hg or higher (48%), pulsatile metatarsal waveforms (67%), and/or toe pressure higher than 55 mm Hg (36%). All patients underwent a primary single- or multiple-digit amputation (through the interphalangeal joint, metatarsal head, or metatarsal shaft). Additional forefoot procedures (debridement, digit amputation) were performed during the follow-up period as needed for persistent or recurrent infection. The main outcome variables were recurrent or persistent foot infection (defined as requiring rehospitalization for antibiotics, wound care, and/or reoperation), the number of repeat operations and hospitalizations for salvage of limbs with recurrent or persistent infections, and time to complete forefoot healing or foot amputation. RESULTS: Ninety-two patients who had diabetes mellitus with 97 forefoot infections comprised the study group. Ninety-seven primary digit amputations (34 through interphalangeal joints, 28 through metatarsal heads, 35 through metatarsal shafts) were performed. The median length of hospital stay was 10 days. There were no operative deaths. The mean follow-up period was 21 months (range, 3 days to 105 months). The primary amputation healed (without persistent infection) in only 38 limbs (39%), at a mean time of 13 +/- 10 weeks. Twenty-three limbs (24%) had not healed the primary amputation without evidence of persistent infection at last follow-up (mean, 12 weeks). Infection persisted in 35 limbs (36%), and infection recurred in 15 of 38 (40%) healed limbs. An average of 1.0 reoperations (range, 0 to 3) and 1.6 rehospitalizations (range, 1 to 4) were involved in salvage attempts in these recurrent/persistent infections. Five persistent and five recurrent infections ultimately healed (mean, 53 weeks). Complete healing was achieved in only 33 of 97 limbs (34%). Twenty-two foot amputations (20 transtibial, two Syme's) were performed (mean, 49 +/- 74 weeks; 20 for persistent infection). Eighteen persistent/recurrent infections remained unhealed at the last follow-up examination (mean, 105 weeks). CONCLUSION: Patients with diabetes mellitus who have sepsis limited to the forefoot requiring acute hospitalization and undergoing primary digit amputations have a high incidence of intermediate-term, persistent, and recurrent infection, leading to a modest rate of limb loss, despite having apparently salvageable lesions and noninvasive evidence of presumed adequate forefoot perfusion.     

Immunogenicity of peptides derived from a fibronectin-binding protein of S. aureus expressed on two different plant viruses

The D2 peptide derived from an S. aureus fibronectin-binding protein (FnBP) was expressed on the surface of the icosahedral cowpea mosaic virus (amino acids 1-30 of D2) or on the rod-shaped potato virus X (amino acids 1-38 of D2), termed CPMV-MAST1 and PVX-MAST8, respectively. Mice and rats were immunized subcutaneously with CPMV-MAST1 and mice with PVX-MAST8 in adjuvant and high titres of FnBP-specific antibody were obtained. The mouse IgG was predominantly of the IgG2a and IgG2b isotypes, which strongly bound complement component C1q, suggesting a TH1-bias in the peptide-specific responses. Sera from mice and rats immunized with CPMV-MAST1 and from mice immunized with PVX-MAST8 were shown to completely inhibit the binding of fibronectin to immobilised recombinant FnBP and rat sera against CPMV-MAST1 were able to block adherence of S. aureus to fibronectin. These studies demonstrate that the D2 peptide is highly immunogenic when expressed on 2 different plant viruses and highlight the potential of plant virus-based vaccines to protect against S. aureus infections.     

Spontaneous abortion in the British semiconductor industry: An HSE investigation. Health and Safety Executive.

BACKGROUND: The UK Health and Safety Executive (HSE) conducted a study to examine the risk of spontaneous abortion (SAB) in British female semiconductor industry workers, following reports from the USA which suggested an association between risk of SAB and work in fabrication rooms and/or exposure to ethylene glycol ethers. METHODS: A nested case-control study based on 2,207 women who had worked at eight manufacturing sites during a 5-year retrospective time frame was established; 36 cases were matched with 80 controls. RESULTS: The overall SAB rate in the industry was 10.0%. (65 SABs/651 pregnancies) The crude odds ratio (OR) for fabrication work was 0.65 (95% CI 0.30-1.40). This was essentially unchanged after adjustment for a range of potential confounding factors in the first 3 months of pregnancy and was reduced to 0.58 (95% CI 0.26-1.30) after adjustment for smoking in the previous 12 months. There were no statistically significantly elevated ORs for any work group or any specific chemical or physical exposure in the industry. CONCLUSIONS: There is no evidence of an increased risk of SAB in the British semiconductor industry. Am. J. Ind. Med. 36:557-572, 1999. Published 1999 Wiley-Liss, Inc.