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Biomedical subjects

J White

Publications and source records attributed to J White.

At least 613 records · Page 34Linked to original sources
PubMedDate not supplied

Guidelines for medical and health information sites on the internet: principles governing AMA web sites. American Medical Association.

Access to medical information via the Internet has the potential to speed the transformation of the patient-physician relationship from that of physician authority ministering advice and treatment to that of shared decision making between patient and physician. However, barriers impeding this transformation include wide variations in quality of content on the Web, potential for commercial interests to influence online content, and uncertain preservation of personal privacy. To address these issues, the American Medical Association (AMA) has developed principles to guide development and posting of Web site content, govern acquisition and posting of online advertising and sponsorship, ensure site visitors' and patients' rights to privacy and confidentiality, and provide effective and secure means of e-commerce. While these guidelines were developed for the AMA Web sites and visitors to these sites, they also may be useful to other providers and users of medical information on the Web. These principles have been developed with the understanding that they will require frequent revision to keep pace with evolving technology and practices on the Internet. The AMA encourages review and feedback from readers, Web site visitors, policymakers, and all others interested in providing reliable quality information via the Web.

American Medical Association↗
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HIV vulnerability and the adult survivor of childhood sexual abuse.

The purpose of this article is to sensitize clinicians working in the field of childhood physical/sexual abuse to the connection between untreated childhood traumatization and HIV high-risk behaviors. The characteristic abuse symptoms of chronic depression, sexual compulsivity, revictimization, and substance abuse are identified as barriers to HIV education and intervention for survivors. An overview of the existing HIV/child abuse connection research, an illustrative case history and a discussion regarding the clinical implications of these connections are offered.

Acquired Immunodeficiency Syndrome↗
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Characteristics of PAHs, PCDD/Fs and PCBs in sediment following forest fires in northern Alberta.

Extensive forest fires occurred in northern Alberta, Canada, in 1998. Polynuclear aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were studied following these forest fires in order to explore natural and anthropogenic influences on the affected forest fire area. Specifically, concentrations and profiles of these compounds were determined in sediment samples. A predominance of alkylated PAH derivatives over parent PAHs were observed at the burned and reference sites. Naturally dervied PAHs were abundant at all sites. A high proportion and concentration of retene was observed at the totally burned site and indicates some inputs from forest fires. Very low concentrations of PCDD/Fs and PCBs were observed at all sites, and the profiles were very similar. This likely reflects common atmospheric contributing sources to the study area.

Air Pollutants↗
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Studies of the effects of 1,25-dihydroxyvitamin D on skeletal and calcium homeostasis and on inhibition of tumor cell growth.

Vitamin D, parathyroid hormone (PTH), and parathyroid hormone-related peptide (PTHrP) are major regulators of calcium metabolism and vitamin D can also reduce the growth of normal cells and tumor cells. PTHrP and PTH act via a common membrane receptor (PTHR). The mouse PTHR is regulated by a kidney-selective upstream promoter P(1) and ubiquitous downstream promoter P(2). In vitro and in vivo 1,25(OH)(2)D can inhibit PTHR expression in bone but not cartilage by downregulating transcription via P(2). Gene transcription of PTHrP per se can also be downregulated by 1,25(OH)(2)D and by low calcemic vitamin D analogs. This inhibitory effect may reduce the hypercalcemia caused by overproduction of PTHrP by tumor cells. In a malignant keratinoctye cell line, phosphorylation of the retinoid X receptor alpha occurs through the activated Ras-MAP kinase pathway and results in attenuated trans-activation by the vitamin D receptor, its heterodimeric partner. This decreases the growth-inhibitory efficacy of 1,25(OH)(2)D. Studies of the capacity of vitamin D to alter PTHrP production and action and of its anti-proliferative effects can, therefore, shed important light on basic mechanisms controlling these events, and may also have major implications for clinical medicine and therapeutics.

Animals↗
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Improving the accuracy of identifying lesbians for telephone surveys about health.

Knowledge about the health status and health care needs of lesbians is limited by the lack of population-based studies, although recent survey methods research offers suggestions that may be relevant to involving lesbians in more rigorous studies. To explore the transferability of findings about the general population to research on lesbian health, focus groups were conducted in 1997-1998 with self-identified lesbians in five U.S. urban areas. Videotaped telephone interviews stimulated discussion about methods for enhancing participation of lesbians in random digit dial telephone surveys. Results are useful for developing improved practices for conducting health surveys with lesbians.

Adolescent↗
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Capillary electrophoresis as a method to study DNA reassociation.

To develop analytical methodology to assess the genetic complexity of a DNA sample, capillary electrophoresis with laser-induced fluorescence detection is used to monitor the annealing process of DNA samples. Coated columns are filled with an entangled polymer solution shown to optimally separate DNA through size-selective capillary electrophoresis. DNA samples are denatured by heating in a boiling water bath for approximately 10 min and then cooled to approximately 25 degrees C below the melting point of the DNA sample to initiate the reassociation process. The DNA is detected by means of the laser-induced fluorescence of intercalated ethidium bromide, which produces a substantially greater signal for double- versus single-stranded DNA. The rate of reassociation is dependent upon the rate at which complimentary strands of DNA encounter each other and the degree of repeating base sequences in the sample (hence, the diversity of the DNA). Experimental parameters also influence the reassociation rate. The effects of salt concentration and incubation temperature are presented. Traditional plots of C(o)t (C(o) = DNA concentration and t = reassociation time) versus % recovery of double-stranded DNA signal are generated for PhiX 174 Hae III digest and 50 bp stepladder DNA, individually and combined, to calculate the reassociation rate constants for these samples. Because reassociation of individual fragments is observed by the CE-LIF method, more information about the samples is available than with less specific and time-consuming traditional methods of investigating DNA reassociation.

DNA↗
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Peptide sequences of T-cell receptor delta and gamma chains are identical to predicted X and gamma proteins.

Although most mature peripheral T lymphocytes express a major histocompatibility complex restricted, CD3-associated, antigen receptor (TCR) which has been well characterized, some T cells carry a different CD3-associated heterodimer on their surface. One of the two disulphide-linked chains of this putative second receptor, which in mice has relative molecular mass (Mr) 35,000 (35K), has been identified as a product of the group of gamma genes. The other chain, termed delta (Mr 45K in mice), is not as well characterized. Although gamma/delta-bearing cells are a minor subset among peripheral T lymphocytes, they are the only CD3+ cells in the thymus early in ontogeny. Taking advantage of these kinetics, we have generated gamma/delta-bearing hybridomas, using a new TCR alpha chain-negative variant of the AKR thymoma BW5147 as tumour parent, fetal thymocytes as normal cell partners, and an anti-CD3 monoclonal antibody (mAb) as screening reagent. Gamma and delta chains from one of these hybrids have been purified and partially sequenced. The sequences obtained indicate that delta is indeed identical to the polypeptide encoded by the recently described gene X, as suggested by Chien et al.

Amino Acid Sequence↗
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Influence of residential fungal contamination on peripheral blood lymphocyte populations in children.

Reported residential fungal contamination has been associated consistently with increased symptoms among occupants; however, an objective measure of a health effect is lacking, and a pathophysiologic mechanism has not been established. Our objective was to determine if exposure to indoor fungal contamination influenced T-cell differentiation. In this study, we contrasted lymphocyte populations, measured by flow cytometry, between a group of children who lived in homes with considerable fungal contamination (n = 39) and a group in less-contaminated homes (n = 20). Indicators of fungal biomass were viable fungi in house dust and air ergosterol in the child's bedroom. Living in a more-contaminated home versus a less-contaminated home was associated with a larger number of CD3+ T cells expressing CD45RO (1.5 x 10(9)/I versus 1.1 x 10(9)/I, respectively; p = .05, two-tailed t testing) and a reduced CD4/CD8 ratio (1.6 versus 1.8, respectively; p = .04). The differences persisted over a 12-mo period, and they were not explained by the child's age or total serum IgE, dust mite antigens, and the presence of furry or feathered pets or a humidifier. The results suggest that residential fungal contamination leads to chronic stimulation of children's lymphocytes.

Air Microbiology↗
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A survey of adult recreational drug use via the World Wide Web: the DRUGNET study.

DRUGNET was a cross-sectional survey of adult recreational drug users (i.e., not abusers) via the World Wide Web of the Internet. The purpose of this survey was to provide a unique, broad description of nondeviant adult recreational drug users. The survey instrument had four divisions: demographic and lifestyle indices, drug use history, legal history and attitudes about drug issues, and the General Well-being Schedule (GWBS). Responses were received from 1,473 self-identified drug users. Of these, 567 completed only the first section, leaving 906 respondents who completed the entire survey. The typical respondent was a White male who was well educated, employed full-time, a participant in recreational and community activities, and who described his physical health status as good. Their mental health, as measured by the GWBS, was similar to the general adult U.S. population. Their drug-taking behavior appeared to be well-controlled, at mild to moderate levels in both frequency of use and degree of intoxication. These findings have major implications for drug policy and indicate the need for further research on the majority of drug users, who may be expected to resemble this sample more than they do clinical populations of drug abusers.

Adolescent↗
PubMedDate not supplied

The role of oxygen-derived free radicals in burn-induced myocardial contractile depression.

The release of oxygen free radicals from ischemic myocardium has been implicated as a causative factor of cardiac dysfunction after thermal injury. In this study, isolated coronary perfused guinea pig hearts were used to determine if free radical scavengers improve left ventricular (LV) intrinsic contractile response to burn shock. Parameters measured included peak isovolumic LV pressure (LVP) and maximal rate of LVP rise (+dP/dtmax) and fall (-dP/dtmax) at a constant preload. Control animals were immersed in body temperature water and divided into four groups: Group 1, untreated N = 10; Group 2, control animals treated with unbound superoxide dismutase (SOD), N = 5; Group 3, control animals treated with ficoll-SOD, N = 5; and Group 4, control animals treated with PEG-SOD, N = 5. Scald burn equivalent to 45% of total body surface area was produced in 64 animals. Fluid resuscitation was initiated immediately after burn in all animals, and animals were then divided into seven burn experimental groups. In Group 5, 10 animals were treated with fluid alone, lactated Ringer's, 4 mL/kg/% burn. Burned animals in Group 6 (N = 10) received a reduced volume of Ringer's 2 mL/kg/% burn plus unbound-SOD, 50 mg/kg; 10 animals in Group 7 received this volume of Ringer's plus ficoll-SOD, 50 mg/kg. In groups 8, 9, and 10 animals were given fluid, lactated Ringer's, 2 mL/kg/% burn plus varying doses of PEG-SOD (Group 8: N = 9, 1,000 U; Group 9: N = 10, 6,000 U; Group 10: N = 5, 12,000 U). In Group 11 (N = 10), animals received SOD-PEG, 6,000 U, plus catalase, CAT-PEG, 6,000 U, given with 4 mL/kg/% burn lactated Ringer's solution. Hypotension, hypothermia, and hemoconcentration were similar in all animals after thermal injury, regardless of treatment regimen. Burn hearts showed significantly lower LVP, +dP/dt max, and -dP/dt max than control hearts (P less than 0.05). Compared to controls, coronary pressure and coronary vascular resistance were significantly higher in all treated burn groups. There was no significant difference in heart rate or time to peak pressure or time to maximal contraction or relaxation among the groups. Left ventricular function curves for burned hearts were shifted downward and to the right of curves obtained from control hearts (P less than 0.01), regardless of scavenger treatment. PEG-SOD, 6,000 U, improved left ventricular contractility (+dP/dt) at maximal levels of end-diastolic pressure but deficits in left ventricular pressure and relaxation persisted.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
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Managing drug interactions with oral contraceptives.

An increasing concern to nurses is the possibility of drug interactions involving oral contraceptives. Information regarding the mechanisms, significance, and management of drug interactions with oral contraceptives is provided. Approaches to counseling patients also are discussed.

Anti-Bacterial Agents↗
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Intermediate filament expression of ductal carcinoma cells in fine needle aspirates of the breast.

OBJECTIVE: To assess the frequency of occurrence of vimentin expression in fine needle aspirates of ductal carcinoma of the breast and the association of vimentin expression with established prognostic indicators. STUDY DESIGN: Cytocentrifuge preparations made from fine needle aspirates of 51 cases of ductal carcinoma were studied. RESULTS: Vimentin expression, detected in 61% of cases, was positively associated with tumor size, lymph node status, tumor grade, growth fraction and negative estrogen receptor status, but only in the case of lymph node status did the association reach the level of statistical significance. CONCLUSION: Vimentin expression can be detected in breast cancer using fine needle aspiration. Further study is necessary to determine whether it provides independent prognostic information.

Biopsy, Needle↗
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Medicare reform.

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Budgets↗