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Biomedical subjects

J White

Publications and source records attributed to J White.

At least 307 records · Page 17Linked to original sources
PubMed1995

Lethal experimental infections of rhesus monkeys by aerosolized Ebola virus.

The potential of aerogenic infection by Ebola virus was established by using a head-only exposure aerosol system. Virus-containing droplets of 0.8-1.2 microns were generated and administered into the respiratory tract of rhesus monkeys via inhalation. Inhalation of viral doses as low as 400 plaque-forming units of virus caused a rapidly fatal disease in 4-5 days. The illness was clinically identical to that reported for parenteral virus inoculation, except for the occurrence of subcutaneous and venipuncture site bleeding and serosanguineous nasal discharge. Immunocytochemistry revealed cell-associated Ebola virus antigens present in airway epithelium, alveolar pneumocytes, and macrophages in the lung and pulmonary lymph nodes; extracellular antigen was present on mucosal surfaces of the nose, oropharynx and airways. Aggregates of characteristic filamentous virus were present within type I pneumocytes, macrophages, and air spaces of the lung by electron microscopy. Demonstration of fatal aerosol transmission of this virus in monkeys reinforces the importance of taking appropriate precautions to prevent its potential aerosol transmission to humans.

Aerosols↗
PubMed1995

A community-wide RN refresher course: a collaborative success.

By combining forces, nurse educators and practitioners developed a unique RN refresher course that provided a supportive environment for successful reentry into professional nursing practice. Nursing faculty and administrators from a baccalaureate nursing program collaborated with nursing clinicians from seven acute care hospitals to meet the assessed needs of community nurses for reentry programs. The collaborative effort provided accessible courses at lower costs with qualified faculty and a variety of clinical practice experiences for nurses areawide. This article describes the planning, development, implementation, and analysis of this successful areawide RN refresher course.

Community Health Nursing↗
PubMed1995

Are serum concentrations of nitric oxide metabolites useful for predicting the clinical outcome of severe ulcerative colitis?

OBJECTIVE: To determine serum concentrations of nitric oxide metabolites (NOX) in patients with severe ulcerative colitis and to assess whether these concentrations predict clinical outcome. PATIENTS: Twenty-six patients (16 men and 10 women, mean age 46 years) with severe ulcerative colitis requiring hospitalization for parenteral steroid therapy. Thirteen patients had a complete clinical response and symptoms resolved after 5 days of parenteral steroid administration; 13 made an incomplete recovery and needed further treatment (six cyclosporin, seven colectomy). METHODS: Serum concentrations of NOX and C-reactive protein (CRP) were measured daily for 3 days in all patients and as clinically indicated thereafter. The normal range for NOX was established by measuring the concentration in 25 healthy controls. RESULTS: Mean serum NOX and CRP concentrations were significantly elevated in both the patients with a complete and those with an incomplete response compared with controls (P < 0.001) on day 1 and fell during the first 3 days of therapy. On day 3, mean serum concentrations of NOX and CRP were lower in the patients with a complete response, but only the difference in CRP attained statistical significance (P = 0.02). There was no correlation between NOX and CRP concentrations. CONCLUSIONS: In the majority of patients with severe ulcerative colitis, circulating concentrations of NOX are increased at presentation and fall promptly during parenteral steroid therapy, irrespective of clinical outcome. However, in a small number of patients NOX concentrations do not fall during steroid treatment and such patients will probably require additional medical therapy or surgery.

Adult↗
PubMed1994

Rejection of rat skin xenografts by either murine CD4 or CD8 T cells.

Although xenografts can be rejected by humoral or cellular mechanisms, the relative contribution of each remains unknown for any given recipient-donor combination. Moreover, the cells involved in cell-mediated events, as well as the mechanisms by which these cells recognize xenoantigens, remain controversial. It would be advantageous to have a model in which either, as well as various parts of either, could be investigated in the absence of the other, as well as in the absence of events taking place during organ engraftment. In the present report, rejection of rat skin xenografts was monitored after adoptive transfer of unique populations of highly purified lymphoid cells to previously transplanted immunodeficient C.B17 Scid/Scid mice. Purified T cells and, unexpectedly, purified CD4+ T cells alone and purified CD8+ T cells alone rejected rat xenografts. Alternatives that may explain these findings are discussed.

Animals↗
PubMed1994

The epidemiology of measles in England and Wales: rationale for the 1994 national vaccination campaign.

An epidemic of between 100,000 and 200,000 cases of measles during 1995 has been predicted in England and Wales. This prediction was based on epidemiological evidence from several sources. Notifications of measles to the Office of Population Censuses and Surveys have risen in 1994, with a high proportion of cases in children aged over 10 years. An increase in the incidence of measles was seen in data from other sources, including laboratory reports of confirmed infections and consultations with general practitioners for new episodes of measles. Antibody tests were performed on saliva and serum from notified cases in several districts. Over three quarters of the notified cases in 1994 that were confirmed occurred in children of school age. The proportion of children aged 7 to 14 years who were susceptible to measles, obtained from studies of the age specific prevalence of antibody, rose from 6.0% (146/2453) in 1986 and 1987 to 9.2% (144/1565) in 1991. Mathematical modelling has predicted that the level of susceptibility anticipated in the school age population in 1995 would have been sufficient to allow a resurgence of measles. Over half of the cases in the resulting epidemic would have occurred in people aged at least 10 years and, because mortality is higher in this older age group, between 30 and 60 deaths would have occurred. A mass campaign to immunise all children of school age is expected to cause an immediate reduction in disease transmission and prevent a substantial toll of morbidity and mortality.

Adolescent↗
PubMed1994

Caulobacter flagellar function, but not assembly, requires FliL, a non-polarly localized membrane protein present in all cell types.

Caulobacter crescentus has a single polar flagellum, which is assembled in the predivisional cell. Known flagellar genes encode structural and regulatory components that are required for flagellar assembly and function. These genes are organized in several classes which form a transcriptional regulatory hierarchy. A member of the Class II genes, the fliLM operon, encodes homologs of the Escherichia coli flagellar switch protein, FliM, and a protein with a hitherto unknown function, FliL. We report here that flagellar rotation requires the FliL protein. In-frame deletions in the chromosomal copy of the fliL gene result in cells that form a flagellum but are non-motile. The FliL protein was found to be associated with the inner membrane and to be present in all cell types. This is the first report of a Caulobacter crescentus protein that is essential for motility but is not spatially restricted to the region of the flagellar basal body. Although FliL is required for flagellar function, it is not part of the transcriptional hierarchy, supporting the hypothesis that, as is the case for the enterics, the regulatory hierarchy responds to assembly cues rather than directly to the expression of flagellar proteins.

Amino Acid Sequence↗
PubMed1994

A spectroscopic study of the mitochondrial transit peptide of rat malate dehydrogenase.

A peptide corresponding to the N-terminal sequence of the rat malate dehydrogenase, comprising the transit sequence and two residues of the mature protein (MLSALARPVGAALR-RSFSTSAQNNAK) has been chemically synthesized, and its structural characteristics investigated by Fourier-transform i.r. (FT-IR), c.d. and 1H-n.m.r. spectroscopy. FT-IR and c.d. spectra of the peptide were recorded in a variety of environments (aqueous solution, trifluoroethanol) and after incorporation into phospholipid bilayers. The peptide was found to be mainly in aperiodic or undefined conformation in aqueous solution. However, in trifluoroethanol a marked increase in alpha-helical content was observed. An increase in alpha-helical content was also observed in negatively charged lipids (dimyristoylphosphatidylglycerol and cardiolipin). However, when reconstituted in a zwitterionic phospholipid (dimyristoylphosphatidylcholine), no alpha-helical structure was observed. N.m.r. spectroscopy was used to characterize the helical structure in greater detail in trifluoroethanol. The 1H-n.m.r. spectrum of the peptide in this solvent was assigned using standard homonuclear two-dimensional methods. The observed patterns of nuclear Overhauser enhancements confirmed the deductions obtained from c.d. and FT-1R spectroscopy concerning the solution conformation, suggesting a region of flexible nascent helix between Ala-4 and Ser-18. This structure is discussed in terms of the possible function of the peptide.

Alanine↗
PubMed1994

Binding of a soluble alpha beta T-cell receptor to superantigen/major histocompatibility complex ligands.

The genes for the alpha and beta chains of a murine T-cell receptor were truncated just prior to the portions encoding the transmembrane regions and introduced into baculovirus by recombination. Insect cells infected with the virus secreted a soluble form of the receptor that could be purified to homogeneity. This soluble receptor reacted with a set of six monoclonal antibodies originally raised to different epitopes on the natural transmembrane-region-containing receptor and bound with appropriate specificity to a cell surface complex of the human major histocompatibility complex class II molecule DR1 with the bacterial superantigen staphylococcal enterotoxin B.

Amino Acid Sequence↗
PubMed1994

Production of soluble MHC class II proteins with covalently bound single peptides.

The alpha beta T-cell receptors (TCRs) react with complex ligands composed of peptides bound to major histocompatibility complex (MHC) proteins. In the absence of foreign antigens the peptides bound to MHC molecules come from the proteins of the host itself. Interactions between TCRs and these self-peptide-MHC ligands work positively to drive T-cell development in the thymus and negatively to delete or inactivate T cells with potential self-reactivity. On the cell surface, MHC proteins are associated with many different self peptides, making it impossible to know which self peptide was involved in positive or negative interactions with a particular T cell. These studies as well as in vitro studies on TCR-peptide-MHC interactions would be aided by a means of producing MHC molecules containing a single peptide. We have tackled this problem for MHC class II proteins by genetically attaching the peptide by a flexible peptide linker to the amino terminus of the class II beta-chain. Here we report that a secreted, soluble form of this covalent peptide-MHC complex can be expressed in insect cells. The peptide is engaged by the peptide-binding groove of the secreted MHC molecule and this complex is recognized by T cells bearing receptors specific for that combination.

Amino Acid Sequence↗
PubMed1994

Prenatal sonographic detection of intra-abdominal extralobar pulmonary sequestration: report of three cases and literature review.

Three cases of intra-abdominal extralobar pulmonary sequestration detected antenatally by ultrasound are reported. One case was associated with a large left diaphragmatic hernia. Sonographically, all the cases were found in the left supra-renal region presenting as a well-defined echogenic mass with cystic hypoechoic areas. The condition should be considered in the differential diagnosis of all antenatally detected upper abdominal echogenic masses, particularly when associated with a diaphragmatic hernia. Postnatal ultrasound-guided fine needle aspiration biopsy in one case yielded respiratory type epithelium and this procedure could provide a reasonably confident diagnosis of the lesion.

Abdomen↗
PubMed1994

"Oh, by the way ...": the closing moments of the medical visit.

OBJECTIVE: To define and describe the communication between physicians and patients in the closing phase of the medical visit. To identify types of communication throughout the visit that are associated with the introduction of a new problem during the closing moments of the visit or with longer closures. DESIGN: Audiotaping of office visits. Tapes were analyzed using a modified Roter Interactional Analysis System (RIAS). The coders' definition of closure was compared with the opinion of communication experts. SETTING: Outpatient offices of practicing physicians. PARTICIPANTS: Eighty-eight patients visiting 20 primary care physicians participated. Physicians were selected by a letter from the Oregon Board of Medical Examiners. The mean number of years from graduation was 16 (range 3-47). One physician per site participated. MEASUREMENTS: Frequencies of physician and patient communication behaviors and global affect scores were calculated and correlations were drawn using t-test and chi-square analyses. RESULTS: The physicians initiated the closing in 86% of the visits. The physicians clarified the plan of care in 75% of the visits and asked whether the patients had more questions in 25% of the cases. The patients introduced new problems not previously discussed in 21% of the closures. New problems in closure were associated with less information exchanged previously by physicians and patients about therapy (t = -3.28, p = 0.002; t = -2.26, p = 0.03), fewer orientation statements by physicians (t = 1.86, p = 0.001), and higher patient affect scores (t = 0.252, p = 0.016). Long closures (> 2 minutes) correlated with physicians' asking open-ended questions (0.2438; p = 0.019), laughing (0.3002; p = 0.005), showing responsiveness to patients (0.3996; p < 0.001), being self-disclosing (0.3948; p < 0.001), and engaging in psychosocial discussion with patients (0.2410; p = 0.020). CONCLUSION: This study is the first description of how physicians and patients communicate during the closing of office visits. Notably, the patients raised new problems at the end of the visit in 21% of the cases. The findings suggest ways physicians might improve communication in the closing phase of the medical interview. Orienting patients in the flow of the visit, assessing patient beliefs, checking for understanding, and addressing emotions and psychosocial issues early on may decrease the number of new problems in the final moments of the visit.

Communication↗
PubMed1994

Comparative study on the procoagulant from the venom of Australian brown snakes (Elapidae; Pseudonaja spp.).

The procoagulant was isolated from the venom of four clinically significant species of brown snake; Pseudonaja affinis, P. inframacula, P. nuchalis, and P. textilis. HPLC elution profiles and PAGE showed a high degree of homology between the procoagulants from the four species. Antiserum from the CSL Ltd (Brown Snake Antivenom) produced a single band against all four procoagulants. The specific activity of the procoagulant varied between species, while inhibitory studies indicated that the procoagulants were serine proteases with a sialic acid component which also contributes to the coagulant action.

Animals↗