Water-soluble nicotinic acetylcholine receptor formed by alpha7 subunit extracellular domains

Water-soluble models of ligand-gated ion channels would be advantageous for structural studies. We investigated the suitability of three versions of the N-terminal extracellular domain (ECD) of the alpha7 subunit of the nicotinic acetylcholine receptor (AChR) family for this purpose by examining their ligand-binding and assembly properties. Two versions included the first transmembrane domain and were solubilized with detergent after expression in Xenopus oocytes. The third was truncated before the first transmembrane domain and was soluble without detergent. For all three, their equilibrium binding affinities for alpha-bungarotoxin, nicotine, and acetylcholine, combined with their velocity sedimentation profiles, were consistent with the formation of native-like AChRs. These characteristics imply that the alpha7 ECD can form a water-soluble AChR that is a model of the ECD of the full-length alpha7 AChR.     

The envelope glycoprotein ectodomains determine the efficiency of CD4+ T lymphocyte depletion in simian-human immunodeficiency virus-infected macaques

CD4+ T lymphocyte depletion in human immunodeficiency virus type 1 (HIV-1)-infected humans underlies the development of acquired immune deficiency syndrome. Using a model in which rhesus macaques were infected with chimeric simian-human immunodeficiency viruses (SHIVs), we show that both the level of viremia and the structure of the HIV-1 envelope glycoprotein ectodomains individually contributed to the efficiency with which CD4(+) T lymphocytes were depleted. The envelope glycoproteins of recombinant SHIVs that efficiently caused loss of CD4(+) T lymphocytes exhibited increased chemokine receptor binding and membrane-fusing capacity compared with those of less pathogenic viruses. These studies identify the HIV-1 envelope glycoprotein ectodomains as determinants of CD4(+) T lymphocyte loss in vivo and provide a foundation for studying pathogenic mechanisms.     

Traumatic brain injury causes delayed motor and cognitive impairment in a mutant mouse strain known to exhibit delayed Wallerian degeneration

Delayed Wallerian degeneration after neuronal injury is a feature of the C57BL/Wld(s) mouse mutant. In the present study, we examined the effect of unilateral controlled cortical impact (CCI) on motor and cognitive performance in C57BL/6 and C57BL/Wld(s) mice. Performance on a beam-walking task was impaired in both injured groups over the first 3 weeks; however, between 28 and 35 days post injury, C57BL/6 mice continued to improve whereas C57BL/Wld(s) mice showed increased footfaults. In a spatial learning task, C57BL/Wld(s) animals performed consistently better than C57BL/6 mice when tested 7-10 days and 14-17 days following CCI. C57BL/Wld(s) mice also demonstrated improved working memory performance as compared with C57BL/6 mice when trained on days 21-22 after injury; this effect was lost on days 23 and 24, and was not evident in other animals tested in the same task at 28-31 days following injury. These results indicate a marked delay in motor and cognitive impairment following CCI in C57BL/Wld(s) mice compared with injured C57BL/6 controls. This is consistent with previous work showing delayed temporal evolution of neuronal degeneration in C57BL/Wld(s) mice and suggests CCI may be a suitable model for examining the functional consequences of traumatic brain injury (TBI) in genetically altered mice.     

Randomized trial of recombinant human interleukin-3 versus placebo in prevention of bone marrow depression during first-line chemotherapy for ovarian carcinoma

PURPOSE: To determine whether recombinant human interleukin-3 (rhIL-3) reduces bone marrow depression and improves chemotherapeutic schedule adherence in ovarian cancer patients receiving first-line combination chemotherapy. PATIENTS AND METHODS: In a randomized multicenter study, 185 patients received carboplatin (dose based on projected area under the concentration-time curve [AUC]=4) and cyclophosphamide (750 mg/m2) day 1, every 3 weeks for six cycles. Patients were randomized to receive rhIL-3 (5 microg/kg) or placebo once daily subcutaneously on days 3 to 12. RESULTS: Adherence to chemotherapeutic regimen, mean chemotherapy cycle length, tumor response rate, and median survival at 24 months did not differ between groups. The number of side effects-primarily allergic reactions, flu-like symptoms and fever-were higher in the rhIL-3 group, which resulted in 21 discontinuations compared with one in the placebo group. Compared with placebo, the rhIL-3 group had higher platelet counts day 1 of cycles 2 to 6. The number of patients with World Health Organization (WHO) grade IV thrombocytopenia or number of platelet transfusions did not differ. Leukocyte counts differed only in cycles 1 and 2 between groups. The leukocyte nadir occurred earlier in the rhIL-3 (day 12) than in the placebo group (day 15, P=.006). Leukocytes and neutrophils were only higher in the rhIL-3 group day 1 of cycle 2. In cycles 4 and 5, more patients with WHO grade IV neutropenia received rhIL-3 (P < .005). Eosinophil counts were higher day 1 of cycles 2 to 6 in the rhIL-3 group (P < .0001). CONCLUSION: rhIL-3 had stimulatory hematopoietic effects. This did not result either in reduction of platelet transfusions or in improvement of chemotherapeutic schedule adherence. There were more side effects in the rhIL-3 group than in the placebo group. rhIL-3 at 5 microg/kg/d is, therefore, not of clinical benefit in this chemotherapeutic regimen.     

Guidelines for surgical procedures after liver transplantation

The ability to acquire a motor and cognitive skill was investigated in 26 patients with schizophrenia and 26 normal participants using repeated testing on the Tower of Toronto puzzle. Seven patients with defective performance were retested using additional trials and immediate feedback designed to facilitate problem solving. A component analysis of performance was used based on J. R. Anderson's (1987) model of cognitive skill learning. Patients exhibited a performance deficit on both motor and cognitive skills. However, their acquisition rate was similar to that of normal participants on most parameters, indicating that skill learning suffered little or no impairment. Performance deficit was accounted for by poor problem-solving ability, explicit memory, and general intellectual capacities. It was remediable in some, but not all, patients. Remediation failure was also related to severe defects of cognitive functions.     

Diagnosis of renovascular disease by extra- and intrarenal Doppler parameters

It is still a matter of debate as to which parameters should be used for noninvasive diagnosis of renovascular disease by renal Doppler sonography (RDS). The accuracy of RDS in the detection of renal artery stenosis (RAS) was tested in 95 consecutive, moderate to severe hypertensive patients (I-II World Health Organization [WHO] stages). Reno-aortic ratio (RAR) for peak systolic velocity (PSV) was also calculated to assist in the diagnosis of significant (>50%) RAS. Paired receiver-operating characteristic (ROC) analysis was plotted for evaluating the relationship between sensitivity and specificity for each parameter. In a subset of 57 kidneys, the influence of blood pressure and age on intraparenchymal parameters was evaluated. Measurements of maximal peak systolic velocity (PSV) at the site of stenosis, RAR for PSV, and minimum acceleration index in the main renal artery showed high accuracy (areas under the ROC curve 0.97, 0.88, and 0.80, respectively). Among intraparenchymal parameters, early systolic acceleration showed the best area under the ROC curve (0.90), but provided a low positive predictive value (29%) and was significantly influenced by blood pressure (multiple r=0.56; p=0.001). Pulsatility and resistive indices were found to be less powerful as absolute values, and both significantly influenced by blood pressure and age (multiple r=0.60 and 0.50; p=0.001, p=0.02, respectively). However, interindividual variance of intrarenal indices should be minimized by calculation of side difference, although this procedure would become misleading or impossible in patients with bilateral RAS or a single kidney, respectively. These results support the use of extraparenchymal parameters for noninvasive detection of RAS, and emphasize that intrarenal parameters cannot be considered as absolute values.     

Aggressive experience affects the sensitivity of neurons towards pharmacological treatment in the hypothalamic attack area

Early investigators of brain stimulation-evoked complex behaviours (attack, escape, feeding, self-grooming, sexual behaviour) reported that experience may affect the behavioural outcome of brain stimulation. This intriguing example of functional neuronal plasticity was later totally neglected. The present experiment investigated the behavioural outcome of in vivo microdialysis perfusion of the glutamate agonist kainate and/or the GABAA antagonist bicuculline into the hypothalamic attack area (HAA) of (1) animals naive to dyadic encounters; (2) animals with a recent aggressive experience (the probe being implanted 6-24 h after the last of a series of dyadic encounters); and (3) animals with an earlier aggressive experience (probe being implanted 2 weeks after the last aggressive experience). On the experimental day, rats received two 5-min infusions during a dyadic encounter lasting 35 min with an unknown opponent. Flow rate was 1.5-2 microliters/min, drug concentrations were 1.8 x 10(-5) and 1.5 x 10(-5) M for kainate and bicuculline, respectively. Behaviour was analysed before, during and after perfusions. Only the combined kainate + bicuculline treatment had significant effects on behaviour at the doses studied. A significant increase in aggressive behaviour was elicited only in animals with a recent aggressive experience, while naive animals and with an earlier experience responded to the treatments by grooming. These results appear to support early observations indicating that one important aspect of brain stimulation effects is previous experience.     

Thiamine triphosphate levels and histopathology. Correlation in Leigh disease

Thiamine and thiamine triphosphate (TTP) values were assayed in various brain regions in 11 controls and 13 patients with subacute necrotizing encephalomyelopathy (SNE, Leigh disease). The TTP values of normal brain were 5% of the total thiamine value. The relative TTP (or % TTP) level was consistently low in the pons, midbrain, and cerebellum of all the SNE brains. Twenty-five percent of the SNE brains had normal TTP levels in the frontal region. The TTP values correlated with the degrees of pathologic involvement in all sampled regions of the brain except the cerebellum. The concentration of thiamine in the mammillary bodies exceeded its concentration elsewhere in both control and SNE brains. The finding of low TTP levels in morphologically abnormal regions supports the hypothesis that TTP deficiency is etiologically related to SNE.     

Urinary creatinine excretion and lean body mass

In a group of 34 adult and child subjects a high correlation (r = 0.988) was found between lean body mass, as determined by potassium-40 counting, and urinary creatinine excretion. The effect of technical errors was reduced by averaging the results of two or three 40K assays on each subject, and by making consecutive 3-day collections of urine. It appears that one can make a reasonable estimate of lean body mass from urinary creatinine excretion.