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Biomedical subjects

J Rogers

Publications and source records attributed to J Rogers.

At least 307 records · Page 17Linked to original sources
PubMed1991

Parvalbumin-immunoreactive neurons in the neocortex are resistant to degeneration in Alzheimer's disease.

Recent studies have stressed the fact that specific neuronal subtypes may display a differential sensitivity to degeneration in Alzheimer's disease. For example, large pyramidal neurons have been shown to be vulnerable, whereas smaller neurons are resistant to pathology. Using a monoclonal antibody against the calcium-binding protein parvalbumin, we investigated the possible changes in a subpopulation of interneurons in two cortical areas known to be strongly damaged in Alzheimer's disease. In the prefrontal cortex as well as in the inferior temporal cortex, we observed no differences in parvalbumin-immunoreactive cell counts or cell size in Alzheimer's disease brains as compared to control cases. Moreover, the general cellular morphology of these neurons was preserved in the Alzheimer's disease cases, in that their perikarya and dendritic arborizations were intact. These results suggest that paravalbumin-immunoreactive cells represent a neuronal subset resistant to degeneration, and further support the hypothesis that the pathological process in Alzheimer's disease involves specific neuronal subtypes with particular morphological and molecular characteristics.

Aged↗
PubMed1991

Defective control of Epstein-Barr virus-infected B cell growth in patients with X-linked lymphoproliferative disease.

We studied the cellular function and lymphokine production of T cells from patients with X-linked lymphoproliferative disease (XLP) when activated by the challenge with Epstein-Barr virus (EBV) infection. We used an assay system in which T cells were stimulated with membrane antigens of autologous EBV-infected B lymphoblastoid cell lines (B-LCL) and we examined cellular and humoral factors derived from the stimulated T cells which control the growth of EBV-infected B-LCL. Immunoglobulin secretion from the autologous B-LCL was suppressed with radiosensitive suppressor cells in the patients with XLP. The degree of suppression was correlated with the immunoglobulin levels in the serum of the patients with acquired hypogammaglobulinaemia (P less than 0.05). In addition, T cells from the patients with XLP failed to produce interferon-gamma (IFN-gamma) (P less than 0.001). Moreover, the T cell supernatants from the patients with XLP were less potent to inhibit the B-LCL growth. This diminished inhibition of the B-LCL growth was correlated well with the decreased concentration of IFN-gamma in the T cell supernatants. These findings suggest that suppressor cells may be activated in the patients with the hypogammaglobulinaemia phenotype of XLP, but the frequent development of B cell lymphoma in hypogammaglobulinaemia indicate that immunoglobulin suppression may not exert enough pressure on the in vivo growth of EBV-infected B cells. The defective secretion of IFN-gamma may be, at least partially, responsible for the abnormal cytotoxic T cell and natural killer activities found in the patients with XLP, and may indicate the clinical evaluation about the preventive injection of IFN-gamma against the development of malignant lymphoma.

Adolescent↗
PubMed1991

Value of transesophageal echocardiography as an adjunct to transthoracic echocardiography in evaluation of native and prosthetic valve endocarditis.

To determine if transesophageal echocardiography provides better visualization of valvular vegetations than transthoracic echocardiography, we used both methods to evaluate 24 consecutive patients (mean age, 54 years; 15 female patients and nine male patients) referred for symptoms suggestive of infectious endocarditis. Ten of the 24 patients had one or more valvular prostheses. Echocardiograms were classified as positive or negative based on visualization of valvular vegetations or abscesses. Of ten patients with a final diagnosis of infectious endocarditis on extended follow-up, transthoracic echocardiography was positive in five patients. Transesophageal echocardiography not only yielded abnormal findings in all ten of these patients, but also revealed additional information in four of the five patients with abnormal transthoracic echocardiographic examinations. Among the 14 patients who, on subsequent follow-up, were found not to have infectious endocarditis, transthoracic echocardiography was normal in 13 and falsely abnormal in one. Transesophageal echocardiography revealed no evidence of infectious endocarditis in any of these patients. The ten patients who were determined to have infectious endocarditis all had positive blood cultures and no alternative cause for their clinical presentation; in seven patients in this group who underwent operative or postmortem evaluation, infectious endocarditis was confirmed. All patients without infectious endocarditis were demonstrated to have other causes for their clinical presentation. We conclude that transesophageal echocardiography is a highly valuable test in the work-up of patients with suspected infectious endocarditis, especially those patients with inconclusive or normal transthoracic echocardiograms. In addition, transesophageal echocardiography may be of benefit to patients with previously documented infectious endocarditis and a complicated clinical course in whom additional cardiac lesions are suspected but not demonstrated by transthoracic echocardiography.

Abscess↗
PubMed1991

Study of an additional 58 DNA markers in five human populations from four continents.

One hundred DNA polymorphisms from 73 loci (42 genes and 31 anonymous DNA segments) were investigated in five populations (Biaka and Mbuti Pygmies, Melanesians, Chinese and Caucasoids). Data for 47 polymorphisms, including 42 of those discussed here, were described previously [Bowcock et al 1987]. Here we report statistical quantities of genetic importance for each gene and population. The average FST for the 100 markers is 0.137 and the average heterozygosity is 0.325. When known genes and anonymous segments are compared there is no significant difference in the average FST values or in the average heterozygosities.

Africa↗
PubMed1991

Development of thrombophlebitis in peripheral veins with Vialon and PTFE-Teflon cannulas: a double-blind, randomised, controlled trial.

A series of 54 normal subjects were randomised to have either a Vialon or a PTFE-Teflon peripheral vein cannula inserted in a vein in each forearm to observe the development of thrombophlebitis. Cannulas were inspected twice daily for up to 5 days to observe the development of three signs, erythema, oedema or hardness and one symptom, pain. Each sign and symptom was recorded twice daily at three points, the cannula insertion site, the mid-point of the cannula and the cannula tip. The degree of change was recorded as less than 1, 1-2 and greater than 2 cm. Any cannula causing any sign greater than 2 cm was removed. By the end of the study over 40% of both types of cannula had been removed. There were no significant differences between the numbers of each type of cannula removed at any time point throughout the duration of the study. There were no significant differences in the amounts of erythema or hardness, but minimally increased swelling was observed at the mid-point of the PTFE-Teflon cannulas (P = 0.022). Despite the theoretical superiority of Vialon as a cannula material, under controlled conditions there appears to be little difference in its inherent capacity to cause the thrombophlebitis.

Adult↗
PubMed1991

Quality of life after gastric bypass for morbid obesity.

One year after gastric restriction surgery, 70 per cent of 118 women completed a questionnaire about lifestyle and eating behaviour changes. Mean weight loss was 35.4 kg. Patients reported a moderate reduction in appetite, and most avoided specific foods which they previously enjoyed, usually because of epigastric discomfort and/or nausea and vomiting. Patients had initiated or resumed a mean of 1.8 activities, most of which involved physical exercise. Sexual interest, enjoyment and frequency were all increased. Raised sexual satisfaction correlated strongly with overall outcome satisfaction. Seventy-two per cent of respondents rated themselves as very pleased, and 18 per cent as fairly pleased, with the overall results of the operation, and responses to the open-ended questions were often strikingly enthusiastic. However, most patients emphasized the difficulty of adjusting to radically new eating habits in the first 2-3 months after surgery, during which they experienced their greatest need for social support and encouragement.

Adult↗
PubMed1990

Activated CD8 binding to class I protein mediated by the T-cell receptor results in signalling.

The CD8 glycoprotein of T cells bind nonpolymorphic regions of class I major histocompatibility complex proteins on target cells and these interactions promote antigen recognition and signalling by the T-cell receptor. Studies using artificial membranes indicated that effective CD8/class I interaction is critical for response by alloantigen-specific cytotoxic T lymphocytes when class I protein is the only ligand on the antigen-bearing surface. But significant CD8-mediated binding of cytotoxic T lymphocytes to non-antigenic class I protein could not be detected in the absence of the alloantigen. These apparently contradictory findings indicate that CD8 binding to class I protein might be activated through the T-cell receptor and the results reported here demonstrate that this is the case. Treatment of cytotoxic T lymphocytes with soluble anti-T-cell receptor antibody activates adhesion of the cytotoxic T lymphocytes to class I, but not class II proteins. The specificity of this binding implies that it is mediated by CD8 and blocking by anti-CD8 antibodies confirmed this. Furthermore, binding of CD8 to class I protein resulted in generation of an additional signal(s) necessary to initiate response at low T-cell receptor occupancy levels.

Alkaloids↗
PubMed1990

Update in the management of prostate cancer.

Prostate cancer remains one of the commonest malignancies in our community, and it appears that its incidence is rising because of the increasing proportion of the aged population. Improved technology, including the development of new tumour markers and tumour imaging techniques, and a gradually increasing community awareness of this disease, may allow earlier diagnosis. In turn, as the proportion of patients presenting with early stage disease increases, improved approaches to the treatment of localized cancer may thus yield increased community cure rates. The mainstay of treatment of advanced disease remains hormonal manipulation. The introduction of the LHRH agonists has provided an alternative to surgical castration, but has not resulted in an improved response rate or survival from first-line therapy. We believe that these agents do not offer a major benefit, when compared with the simple procedure of orchidectomy, notwithstanding the psychological sequelae of castration. With a median survival of less than five years after hormonal manipulation, many patients still require salvage treatment after relapse. New hormonal therapies yield objective and subjective response rates of approximately 15% and 30%, respectively, but the median survival from the time of hormonal failure remains less than one year. Cytotoxic chemotherapy has not provided a panacea, but has shown definite evidence of antitumour activity in this disease. The use of relatively non-toxic single cytotoxic drugs can provide effective palliation of symptoms in up to 40% of patients and may even prolong survival in some patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1990

Population structure of the human pseudoautosomal boundary.

The mammalian sex chromosomes are composed of two genetically distinct segments: the pseudoautosomal region, where recombination occurs between the X and Y chromosomes, and the sex chromosome-specific parts. Between these two segments the human sex chromosomes differ by the insertion of an Alu element on the Y chromosome. We have surveyed the sequence variation in the boundary region using the polymerase chain reaction. Fifty seven Y and sixty X chromosomes from ten different human populations were analysed. The X chromosomes were found to be polymorphic at five positions in a 300-base-pair region. By contrast, all Y chromosomes were identical except for one distal polymorphism shared with the X chromosome.

Base Sequence↗
PubMed1990

Epidermal growth factor receptor expression in demented and aged human brain.

Immunoreactivity to epidermal growth factor receptor (EGFR) was present in the brain vasculature of 13/13 demented elderly patients, but absent in 9/11 non-demented elderly patients. Of the two positive non-demented patients, one had significant Alzheimer's pathology and the other spinal carcinoma. Ultrastructurally, EGFR is localized to the lumenal surface of endothelial cells.

Aged↗