The postconcussional syndrome reappraised

Despite the apparently benign nature of mild head injury, reflected by the short post-traumatic amnesia duration, relative absence of CNS signs and brief hospital stay, a significant number of patients report persistent symptomatology over the weeks or months afterwards. Largely subjective in nature, such symptom clusters are termed the postconcussion syndrome. The discrepancy between the predominantly subjective complaints and negative examination findings has generated uncertainty and debate about the respective causation roles of organic and psychogenic factors. Over the past 30 years evidence for organic brain changes has accumulated through studies of cerebral circulation, neuropsychological deficits, evoked potential recordings and neuroimaging. This paper reviews data from two UK prospective studies of the evolution and course of postconcussional symptomatology using parallel psychosocial, neuropsychiatric, quantitative EEG and brainstem auditory evoked potential recordings. Changes in theta power occurred early with resolution within 10 days. Prolonged brainstem evoked response I-V intervals were seen in between 27% and 46% of patients. Symptom chronicity noted in a minority of people (13%) was associated with a high prevalence of brainstem dysfunction, while the degree of QEEG recovery appeared to relate to the intensity of early symptom reaction to the trauma. Levels of perceived stress at the time of the injury or afterwards were not related to symptom formation, but chronic social difficulties were a feature of the 21% of patients who initially improved but had a late exacerbation of symptoms between 6 weeks and 6 months after the trauma.     

Association between insulin and blood pressure in relation to the influence of body mass index

The relationship between plasma insulin level and systolic blood pressure (SBP) was investigated by multiple linear regression procedure in 410 Chinese non-diabetics. The significant positive correlation between SBP and 2-hour plasma insulin (INS 2h) after 75g glucose load was found in the BMI (body mass index) 15.9-27.0 group (n = 287) after the adjustment for age, sex, BMI, smoking and plasma cholesterol (P = 0.01). However, this significant correlation was gradually diminished with the expansion of the BMI range, ie. P = 0.04 in the BMI 15.9-29.0 (n = 356) group, P = 0.07 in the BMI 15.9-31 (n = 389) group, and P = 0.12 in the BMI 15.9-33 (n = 402) group after the same adjustment of variables. Interestingly, the significant inverse correlation between insulin-BMI interaction term (product of BMI and insulin) and SBP was found (P = 0.04) in the presence of the significant positive correlation between 2-hour plasma insulin and SBP (P = 0.02) after adjustment of the above mentioned five factors in the whole group (BMI 15.9-42.2, n = 410). These results indicated that SBP is independently correlated with plasma insulin level in the studied population, and that the severer obesity may interfere the net effects of insulin on the elevating of blood pressure.     

XPIP 2.2: X Portable Interface Package

The use of mannequin exercises has been a teaching tool in the education of dental students. Various commercially available materials to simulate extraoral facial structure form part of this apparatus, also called a "phantom head." It is not always practical, with cost considerations, to replace this external component when unavoidable wear and tear occurs. An alternative that uses a recycled milk carton is presented as an inexpensive substitute.     

Green tea polyphenols block endotoxin-induced tumor necrosis factor-production and lethality in a murine model

The effects of arginine on cell proliferation and subsequent T helper (Th) 1 and Th 2 cytokine synthesis by murine Peyer's patch (PP) Th cells in vitro and the influence of arginine on the induction of antigen-specific mucosal and systemic immune responses in vivo were examined. When the PP T cells were stimulated with the anti-alpha beta T cell receptor (TCR) antibody in the presence of different concentrations of arginine, a higher proliferative response was observed in the culture with an optimal concentration of arginine compared with that with a minimum amount of this amino acid. The concentration of cytokines in the supernatant, the number of cytokine-producing cells and the cytokine-specific mRNA expression of PP T cells were also increased in a dose-dependent fashion. Furthermore, when mice fed on an arginine-supplemented liquid diet were orally immunized with tetanus toxoid plus cholera toxin as a mucosal adjuvant, a higher level of antigen-specific fecal IgA was observed when compared with the response in mice fed on an arginine-free diet. Taken together, these results suggest that arginine enhanced antigen-specific mucosal immune response resulting from the supporting activation of cell proliferation and subsequent cytokine synthesis of PP Th cells.     

Autonomic and peptidergic innervation of the human larynx

Asymmetry in the face and dentition is a naturally occurring phenomenon. In most cases facial asymmetry can only be detected by comparing homologous parts of the face. The etiology of asymmetry includes: a) Genetic or congenital malformations e.g. hemifacial microsomia and unilateral clefts of the lip and palate; b) Environmental factors, e.g. habits and trauma; c) Functional deviations, e.g. mandibular shifts as a result of tooth interferences. Dental asymmetries and a variety of functional deviations can be treated orthodontically. On the other hand, significant structural facial asymmetries are not easily amenable to orthodontic treatment. These problems may require orthopedic correction during the growth period and/or surgical management at a later point. Patient complaints and desires need to be addressed since they may vary from unrealistic expectations to a lack of concern even in the presence of large deviations. With mild dental, skeletal and soft tissue deviations the advisability of treatment should be carefully considered.     

Tyrosine kinase inhibition prevents deformation-stimulated vascular smooth muscle growth

The goal of this study was to determine the role of tyrosine phosphorylation in transducing deformation-stimulated vascular smooth muscle growth. Rat aorta-derived vascular smooth muscle cells were cultured on flexible silicone elastomer membranes and subjected to cyclic deformation (15 cycles per minute, deformed 2 seconds, relaxed 2 seconds). Deformation significantly increased proto-oncogene expression, [3H]thymidine incorporation, [3H]leucine incorporation, and cell number. Time course studies showed an 8-hour lag between initiation of cell deformation and onset of [3H]thymidine incorporation, with peak levels achieved after 18 to 24 hours. Western analysis of protein blots from deformed cells (10 minutes) demonstrated increased levels of phosphotyrosine-containing proteins having molecular weights of 110 to 130 and 70 to 80 kD. Deformation-stimulated tyrosine phosphorylation was prevented by the tyrosine kinase inhibitor Herbimycin A. Tyrosine kinase inhibition also prevented deformation-stimulated vascular smooth muscle cell growth as measured by [3H]thymidine incorporation. Cyclic deformation stimulates vascular smooth muscle proliferation through activation of tyrosine kinases. Inhibition of tyrosine phosphorylation is an effective means of preventing deformation-induced vascular smooth muscle growth in vitro.     

Clinical features of halothane and enflurane

This is a brief review of some of the salient clinical features of halothane and enflurane, the two most widely used volatile anesthetics in clinical practice today. Although, halothane has an excellent safety record and comes close to being the ideal inhalational anesthetic it does have some undesirable effects, including incompatibility with adrenaline and the possibility of causing disturbed hepatic function when given repeatedly. Enflurane is now established as a satisfactory volatile anesthetic which has considerably less metabolic breakdown than many other agents; if this is reflected in terms of minimal organ toxicity it should continue to have considerable clinical value. The risks of damage to the kidney and cerebral irritability are uncommon but undesirable features of enflurane. In the search of the perfect inhalational anesthetic the most promising compounds will be those with least biotransformation, suitable pharmacokinetics with minimal cardiovascular or respiratory depression and without toxic effects on the liver, kidney or foetus.     

Distinct exocytotic responses of intact and permeabilised chromaffin cells after cleavage of the 25-kDa synaptosomal-associated protein (SNAP-25) or synaptobrevin by botulinum toxin A or B

Botulinum neurotoxin (BoNT) types A and B are Zn2+-requiring endoproteases which potently block neurotransmitter release by cleavage of a 25-kDa synaptosomal-associated protein (SNAP-25) and synaptobrevin, respectively. Synaptobrevin is important for the exocystosis of catecholamines from dense-core granules and evidence is presented here for the involvement of SNAP-25 in this process in neuroendocrine cells. The effects of BoNT/A and BoNT/B on regulated secretion were compared in intact bovine chromaffin cells to investigate the consequences of cleavage of the different targets. Catecholamine secretion elicited by Ba2+, by elevated K+ concentrations or by nicotine was prevented by each toxin. A very good correlation was observed between the extents of SNAP-25 cleavage or synaptobrevin cleavage and inhibition of secretion by BoNT/A or BoNT/B, respectively, which indicates the importance of SNAP-25 and synaptobrevin in regulated exocytosis. Despite truncation of almost the entire SNAP-25 pool by exposure of the cells to BoNT/A, a residual fraction of secretion persisted that was induced by 20microM Ca2+ (and to a lesser extent by 1 mM Ba2+) following permeabilisation. Addition of more BoNT/A failed to reduce this level of secretion. Inclusion of Mg.ATP, which greatly enhanced secretion from permeabilised cells, was required for Ca2+-stimulated or Ba2+-stimulated BoNT/A-resistant secretion. Furthermore, synaptobrevin is essential for this response because the response was not observed in BoNT/B treated cells. In view of the ability of BoNT/E to abolish secretion from permeabilised cells and to delete 26 amino acids from the C-terminus of SNAP-25, it can be deduced that cleavage of only nine residues by BoNT/A does not prevent the resultant truncated form exhibiting attenuated activity under the conditions created by permeabilisation. This identification of a novel component of secretion from permeabilised cells should facilitate investigation of the functional interaction of SNAP-25 with other proteins involved in regulated exocytosis.