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.

The management of common bile duct stones in patients undergoing laparoscopic cholecystectomy

The management of suspected and/or unsuspected common bile duct (CBD) stones in patients undergoing laparoscopic cholecystectomy (LC) is controversial. Decisions on whether to perform an open CBD exploration versus employing therapeutic options such as preoperative/post-operative endoscopic retrograde cholangiography (ERCP) or endoscopic duct exploration are polemic. To determine indications, timing, benefits, and potential morbidity of these approaches, we gathered data on 401 patients undergoing LC within the last 18 months. Indications for preoperative ERCP included jaundice (40%), dilated ducts (28%), elevated amylase (19%) or alkaline phosphatase (21%), suspicion of CBD stones by ultrasound (17%) and "other" (17%). Indications for postoperative ERCP were retained stones (33%) and CBD evaluation (67%). Indications for CBD exploration included abnormal cholangiogram (64%), palpable stones (18%), and other (18%). A significant correlation was observed between suspected stones by ultrasound and stones found by ERCP (P < 0.01). For patients in the "other" category, preoperative ERCP was universally negative (P = 0.04). Overall ERCP morbidity was 4/59 (6.8%), and the overall failure rate for clearing CBD stones was 2/28 (7.1%). The timing of the ERCP did not affect morbidity/mortality. Multivariate analysis revealed that age (P << 0.001), the presence of pre-existing medical risk factors (P << 0.001), and duration of LC (P = 0.0034), but not ERCP (P = 0.08), were the important factors determining LC morbidity. In summary, common bile duct stones can be successfully cleared endoscopically in the majority of patients undergoing LC. Patients with suspected CBD stones should undergo pre-operative ERCP, and strict criteria should be applied in the selection of these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Criteria for the diagnosis of ischemic vascular dementia proposed by the State of California Alzheimer's Disease Diagnostic and Treatment Centers

Accurate diagnosis of vascular dementia is important for the recognition of underlying pathophysiology and the institution of appropriate therapy. It is also important for the determination of the incidence and prevalence of not only vascular dementia but also Alzheimer's disease (AD), since differentiating between these two entities is often problematic. The State of California Alzheimer's Disease Diagnostic and Treatment Centers (ADDTC) herein propose criteria for the diagnosis of ischemic vascular dementia (IVD). These criteria broaden the conceptualization of vascular dementia, include the results of neuroimaging studies, emphasize the importance of neuropathologic confirmation, refine nosology, and identify areas that require further research. Parallel use of the proposed definitions of "possible" and "mixed" categories in the diagnosis of both AD and IVD would ensure compatibility between the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) criteria for AD and the ADDTC criteria for IVD. Uniform classification of subtypes of IVD will improve the generalizability of individual studies and aid in multicenter collaborations.

The relationship of the extrinsic blood supply to regeneration in graft reconstructed peripheral nerves

Median nerves of rats were reconstructed with conventional or vascular nerve grafts. After 2, 3 and 4 weeks, Allen Video-Enhanced Contrast, Differential Interference Contrast (AVEC-DIC) microscopy revealed axonal transport in most preparations, with varying degrees of myelination. Radio-isotope tracer was measured in the nerve. Two and 4 week measurements revealed no difference between the graft types. At 3 weeks the vascular graft group exhibited transport along the entire length of the nerve in contrast to a relatively abbreviated path length in the conventional graft group. Nerve conduction velocities (NCV) were measured proximal to, within and distal to the grafts. Three week NCV showed no difference between the graft types. The 4 week NCV revealed normal values in the vascular graft group at points distal to and within the graft. Significant slowing was seen in the conventional grafts at both points.

Intracranial calcification in hyperparathyroidism associated with gait apraxia and parkinsonism

Two patients with hyperparathyroidism had symmetric calcification of the brain, including the basal ganglia. In both patients, the neurologic disorder included parkinsonism and gait apraxia. Computerized tomography may help define the prevalence and clinical manifestations of this rare syndrome.