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Biomedical subjects

R Jackson

Publications and source records attributed to R Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1999

Effects of long-term consumption of high doses of fish oil concentrates on clinical parameters in male and female rats.

Many studies suggest that a diet supplemented with fish oil concentrates (FOCs) may provide protection against cardiovascular and other diseases. The possible harmful effects of long-term consumption of high doses of FOCs, however, have not been adequately investigated. Corn oil, fish oil (MaxEPA) and various mixtures of the oils were administered by gavage to 120 male and 120 female rats, 5 d/wk for 13 wk at the rate of 5 mL/kg/d. Although MaxEPA had no effect on prothrombin time or activated partial thromboplastin time, it caused a statistically significant diminution of the total serum cholesterol level. Correlations between relative liver and spleen weights and dose levels were positive but a negative correlation was found between dose levels and serum vitamin E concentration. In female rats, the negative correlations between dose levels and serum iron and triglyceride levels were highly significant. The pathology data showed no remarkable lesions in any of the tissues examined. Results of this study suggest that long-term consumption of high levels of FOCs in rats may reduce serum cholesterol and triglycerides and adversely affect serum iron level and relative liver weight in female rats and relative spleen weights in both sexes.

Animals↗
PubMed1999

Studies on activities of invariant chain peptides on releasing or exchanging of antigenic peptides at human leukocyte antigen-DR1.

An invariant chain peptide (Ii77-92; YRMKLPKSAKPVSQMR; 'Ii-Key') enhances 10-50 times baseline levels, the presentation of synthetic antigenic peptides to murine T cell hybridomas, by an exchange mechanism at cell surface MHC class II molecules. Two differing activities, to promote the release of antigenic peptide in the presence or absence in solution of a second antigenic peptide, were characterized with truncation homologs through assays for release or binding of human myelin basic protein biotinylated (*) peptide 90-102 on purified HLA-DR1: 1) release of bound hMBP *peptide from DR1 in the presence or absence of free hMBP peptide in solution, 2) exchange of hMBP *peptide from solution with hMBP peptide on DR1, and 3) binding of hMBP *peptide to 'empty' DR1. Peptides such as Ii81-88, LPKSAKPV, released prebound hMBP *peptide from DR1 without free hMBP peptide in solution. They also exchanged hMBP *peptide from solution for prebound hMBP peptide. Peptides including hIi77-83, LRMKLPK, released hMBP *peptide only when free hMBP peptide was in solution. Nevertheless, hIi77-85, LRMKLPKPP, released hMBP peptide without hMBP peptide in solution. Either type of peptide accelerated hMBP *peptide binding to 'empty' DR1. Competitive binding assays with hMBP *peptide or several *Ii-Key truncation homologs, with respective not biotinylated forms, demonstrated that the Ii77-83, LRMKLPK, binding site was distinct from the HLA-DR1 antigenic peptide binding site.

Amino Acid Sequence↗
PubMed1999

The diagnosis of skin disease.

While there are certain common features in taking a history and doing a physical examination, every health care specialty has its own approach to gathering information. Dermatology is no exception. The purpose of this article is to outline in some detail the history taking and the physical examination commonly used to make a dermatologic diagnosis.

Dermatology↗
PubMed1999

The importance of technique in preventing postoperative sensitivity when placing bonded restorations.

This article has focused on what are thought to be some of the common causes of postoperative sensitivity following placement of adhesive restorations. Of course, there can be many other factors. There are an infinite number of roads or combinations of roads that won't get dentists where they want to go. However, there is a specific road or roads, when taken carefully in the proper sequence, that will predictably get dentists to their destinations. The same is true for bonding. Adhesive dentistry is by no means difficult, but it is exacting. If the rules are understood and followed precisely, dentists will find the results are well worth the effort.

Dental Bonding↗
PubMed1999

Looking ahead...

Explore the source record for details and available documents.

Computer Systems↗
PubMed1998

CC-chemokines enhance the replication of T-tropic strains of HIV-1 in CD4(+) T cells: role of signal transduction.

This study demonstrates that several CC-chemokines, including those that inhibit entry and replication of macrophage-tropic strains of HIV, increase the replication of T cell (T)-tropic strains in CD4(+) T cells. Enhancement of T-tropic HIV replication is observed at early stages of replication, requires signaling through inhibitory guanine nucleotide-binding regulatory (Gi) proteins, and is associated with increased cell surface colocalization of CD4 and the T-tropic HIV coreceptor CXCR4. These findings may further our understanding of the factors that influence the replication and spread of T-tropic strains of HIV in vivo and suggest that the use of cell signaling CC-chemokines as therapeutic agents for the purpose of limiting HIV replication in vivo should be approached with caution.

Anti-HIV Agents↗
PubMed1998

Natural killer cells from human immunodeficiency virus (HIV)-infected individuals are an important source of CC-chemokines and suppress HIV-1 entry and replication in vitro.

Macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES (regulated on activation, normal T cell expressed and secreted), which are the natural ligands of the CC-chemokine receptor CCR5, inhibit replication of MT-2- negative strains of HIV-1 by interfering with the ability of these strains to utilize CCR5 as a coreceptor for entry in CD4(+) cells. The present study investigates the capacity of natural killer (NK) cells isolated from HIV-infected individuals to produce CC-chemokines and to suppress HIV replication in autologous, endogenously infected cells as well as to block entry of MT-2-negative HIV into the CD4(+) T cell line PM-1. NK cells freshly isolated from HIV-infected individuals had a high number of mRNA copies for MIP-1alpha and RANTES. NK cells produced significant amounts of RANTES, MIP-1alpha, and MIP-1beta constitutively, in response to stimulation with IL-2 alone and when they were performing their characteristic lytic activity (K562 killing). After CD16 cross-linking and stimulation with IL-2 or IL-15 NK cells produced CC-chemokines to levels comparable to those produced by anti-CD3-stimulated CD8(+) T cells. Furthermore, CD16 cross-linked NK cells suppressed (49-97%) viral replication in cocultures of autologous CD8/NK-depleted PBMC to a degree similar to that of PHA or anti-CD3-stimulated CD8(+) T cells. In 50% of patients tested, NK-mediated HIV suppression could be abrogated by neutralizing antibodies to MIP-1alpha, MIP-1beta and RANTES; in contrast, CD8(+) T cell-mediated suppression was not significantly overcome upon neutralization of CC-chemokines. Supernatants derived from cultures of CD16 cross-linked NK cells stimulated with IL-2 or IL-15 dramatically inhibited entry of a MT-2-negative strain of HIV, BaL, in the CD4(+)CCR5(+) PM-1 T cell line. These data suggest that activated NK cells may be an important source of CC-chemokines in vivo and may suppress HIV replication by CC-chemokine-mediated mechanisms in addition to classic NK-mediated lytic mechanisms.

CD3 Complex↗
PubMed1998

Natural killer activating receptors trigger interferon gamma secretion from T cells and natural killer cells.

Proliferation of human CD4+ alphabeta T cells expressing a natural killer cell activating receptor (NKAR) has been shown to be enhanced, particularly in response to low doses of antigen, if the target cells present appropriate human class I major histocompatibility complex (MHC) molecules. Here, we show that NKAR also enhance proliferation and killing of target cells by subsets of CD8+ alphabeta and CD8+ gammadelta T cells, as well as by NK cells. Strikingly, interferon gamma secretion from all of these types of lymphocytes was markedly increased by interaction of the NKAR with their MHC class I ligands, independently of enhancement of proliferation. Thus, the recognition of class I MHC molecules by NKAR on both T cells and NK cells may provide a regulatory mechanism that affects immune responses through the secretion of interferon gamma and possibly other cytokines. It represents a signal for cytokine secretion alternative and/or augmentative to that through the T cell receptor.

CD56 Antigen↗
PubMed1998

Cardiovascular disease risk factors in 65-84 year old men and women: results from the Auckland University Heart and Health Study 1993-4.

AIM: To describe the distribution of the major cardiovascular risk factors among older men and women in the Auckland region, New Zealand. METHODS: Means and prevalences of the major cardiovascular risk factors were estimated for non-Maori, non-Pacific Islands men and women in the age groups 65-74 and 75-84 years using data from the 1993-4 survey of the University of Auckland Heart and Health Study, a cross-sectional, population-based study of cardiovascular risk factors. RESULTS: 996 people aged 65-84 years participated, with men and women and the two ten-year age groups almost equally represented. Fewer than half engaged in regular leisure time physical activity; around 35% were overweight (BMI 25-30) and 10% were obese (BMI > 30). Total mean cholesterol levels were higher in women and 46% of women had a cholesterol level > or = 6.5 mmol/L compared with only 17% of men. However, total cholesterol:HDL ratios were higher among men. Age and sex differences in blood pressure were small. Around 50% had raised blood pressure (BP > 150/90) or were currently on antihypertensive medication; only 8% smoked; around 6% were diabetic. Almost 8% had three or all of four major modifiable cardiovascular risk factors (elevated blood pressure, total cholesterol:HDL ratio > or = 6.5, current smoking and physical inactivity). CONCLUSIONS: These results are broadly comparable to those from other Western populations. Differences between 65-74 and 75-84 year age groups are few but important differences in cholesterol, smoking and physical activity between older men and women are noted. These findings indicate that there is considerable potential for prevention of cardiovascular disease among older people.

Aged↗