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R Leonard

Publications and source records attributed to R Leonard.

At least 55 records · Page 3Linked to original sources
PubMed1988

An improved pressure-sensitive capsule for endoscopic measurement of esophageal variceal pressure.

A new small noninvasive pressure-sensitive capsule for the endoscopic measurement of esophageal varix pressure was evaluated and compared to an initial Yale-designed capsule to test the hypothesis that the diameter of the capsule measuring surface is a limiting factor for the accuracy and variability of capsule pressure measurements. Capsule pressures obtained with each capsule, using rabbit mesenteric vessels comparable in size to human esophageal varices, were correlated with direct intraluminal pressure measurements. There was an excellent correlation between capsule pressure measurements obtained with the small capsule and intraluminal pressure (r2 = 0.97) which was significantly greater than the correlation obtained when the initial capsule was studied (r2 = 0.89, P less than 0.01). The variability of capsule pressure measurements obtained with the small capsule was less than that observed when measurements were obtained with the initial capsule (P less than 0.01). Therefore, this new small capsule should provide the most accurate and reproducible noninvasive measurements of variceal pressure.

Animals↗
PubMed1988

Cytopathic effect of human immunodeficiency virus in T4 cells is linked to the last stage of virus infection.

A principal feature of acquired immunodeficiency syndrome is depletion of T4 lymphocytes, which is partly due to a direct cytopathic effect of the virus. Both syncytial formation (viral-induced cell fusion) and premature cell death have been cited as the major cause for this phenomenon. By kinetic analysis of cell proliferation and cell lysis we show that the cytopathic effect correlates chiefly with virus production from infected cells, including giant syncytial cells. Most T4 cells were, at least transiently, infected by human immunodeficiency virus (human T-lymphotropic virus type IIIB strain); however, after phytohemagglutinin activation, only 10-30% of infected cells express virus (and die) at any one time, indicating that virus production, followed by cell killing, is linked to immune activation and cell differentiation. We also show that an interval exists before viral release, in which expression of viral antigens occurs on the cell surface, suggesting that infected cells are immunogenic before viral production. If so, they may induce a cell-mediated immune response that could minimize dissemination of human immunodeficiency virus, a possibility that has influenced our approaches to the development of a vaccine for prevention of acquired immunodeficiency syndrome.

Cell Line↗
PubMed1988

Influence of an enriched dietary sodium chloride regime during gestation and suckling and post-natally on the ontogeny of hypertension in the rat.

Brattleboro rats without diabetes insipidus were subjected to sodium chloride enrichment (20-fold increase in dietary salt) at various stages of their development. Salt supplementation in the adult rat produced higher systolic blood pressure (SBP), particularly in males (142 +/- 3 versus 110 +/- 3 mmHg in control. The blood pressures of females on salt-supplemented diets during pregnancy decreased from 136 +/- 1 to 121 +/- 2 mmHg, although throughout this period the blood pressures for these rats were greater than for the control pregnant rats. Pregnant females on salt-supplemented diets also showed higher sodium concentrations in the amniotic fluid compared with controls (155 +/- 3.4 versus 134.1 +/- 6.0 mmol/l). Salt supplemented lactating mothers produced milk with similar sodium concentrations to those of the controls, but the urinary sodium concentrations of pups suckling on the former were greater than in the controls. It is concluded that the suckling pups were also salt-enriched. Rats were submitted to salt-enriched regimes in utero, during suckling, post-weaning and post-pubertally, or permutations thereof. Salt supplementation post-weaning led to consistent elevation in arterial blood pressure with males being more susceptible than females. The degree of elevation was increased if the salt-supplement was present during suckling (132 +/- 1 versus 112 +/- 1 mmHg) and was greatest when the salt-supplemented regime was administered both in utero and during the post-weaning period (154 +/- 2 versus 112 +/- 1 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)

18-Hydroxydesoxycorticosterone↗
PubMed1987

Genomic diversity of Zairian HIV isolates: biological characteristics and clinical manifestation of HIV infection.

We describe here several African isolates of HIV, compare them to U.S.-European prototype isolates and to each other, correlate the number of isolates with serological results, and provide insights into the disease spectrum associated with HIV infection in Africa. Three of 25 healthy Zairian donors and 54 of 87 Zairian patients selected for specific pathology and hospitalized in the internal medicine department of the University Clinic of Kinshasa, Zaire, were HIV positive over a six month period in 1985 either by serum antibody (42 cases) or virus isolation (40 cases). The virus positive cases showed a decrease in number of T4 cells and interleukin-2 (IL2) production by mononuclear cells. Restriction endonuclease analysis of HIV sequences from these isolates showed that genomic diversity is also observed in the Zairian isolates but closely related viruses could also be found, similar to the spectrum of diversity among isolates obtained from the U.S. and Europe. A number of isolates (12 of 40) were obtained from serum antibody negative adults. These results are difficult to explain by viral antigenic diversity alone since hybridization with a HTLV-III-B (clone BH10) probe under stringent conditions indicated an overall high degree of relatedness. Rather, these results indicate that some African HIV infected patients fail to make detectable antibodies to HIV or the antibodies were bound in immune complexes not detectable by current techniques.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Long-term cultures of HTLV-III--infected T cells: a model of cytopathology of T-cell depletion in AIDS.

Long-term cultures were established of HTLV-III-infected T4 cells from patients with the acquired immune deficiency syndrome (AIDS) and of T4 cells from normal donors after infection of the cells in vitro. By initially reducing the number of cells per milliliter of culture medium it was possible to grow the infected cells for 50 to 60 days. As with uninfected T cells, immunologic activation of the HTLV-III-infected cells with phytohemagglutinin led to patterns of gene expression typical of T-cell differentiation, such as production of interleukin-2 and expression of interleukin-2 receptors, but in the infected cells immunologic activation also led to expression of HTLV-III, which was followed by cell death. The results revealed a cytopathogenic mechanism that may account for T4 cell depletion in AIDS patients and suggest how repeated antigenic stimulation by infectious agents, such as malaria in Africa, or by allogeneic blood or semen, may be important determinants of the latency period in AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Hematology reference values for peripheral blood of laboratory rats.

Reference values for peripheral red and white blood cells, platelets and coagulation parameters from 11 and 18-week-old Charles River Sprague Dawley rats [Cr1:COBS CD(SD)] were obtained using automated methods. The Coulter Model S Senior, the Clay Adams Ultra-Flo Platelet Counter and the Sherwood Lancer Coagulyzer, were used to measure these parameters on 25 rats/sex. Detailed information on instrumentation or assay methods, and the animals, their source, environment and blood collection method was given. Platelet counts were in the range of 694 X 10(9)/1 to 1412 X 10(9)/1 which was higher than previously reported. In general, the remaining ranges were similar to previously published reference ranges.

Animals↗
PubMed1985

Mass evacuation in disasters.

The emergency physician plays an important role in disaster planning and management. Some disasters will require the removal of a segment of the population for their own safety; this removal is referred to as mass evacuation. This aspect of disaster planning is frequently ignored or, at best, given a few short sentences in overall plans for coping with disasters. Very little has been written on this important aspect to permit one to make intelligent evacuation plans. This article summarizes previous studies on the reactions of people to, and their behavior during, actual mass evacuations. The information is used to outline important points that must be addressed by all those involved in disaster plans so that people may be removed from danger quickly, with as few problems as possible.

Communication↗
PubMed1985

Improved survival following combined radiation therapy and chemotherapy for unfavorable prognosis stage I-II non-Hodgkin's lymphomas.

A retrospective analysis of 144 patients with stage I-II non-Hodgkin's lymphoma (NHL) treated between June 1968 and December 1980 was performed. Patients were staged by bone marrow biopsy, chest radiography, blood chemistries, and either bipedal lymphangiography, computerized axial tomography, or surgical exploration of the abdomen. Patients were subclassified by extent of disease; minimal disease was defined as less than 10 cm and involved one or two contiguous sites, while patients with disease exceeding these limitations were considered to have extended stage I-II disease. Treatment consisted of radiation therapy (RT) alone in 74 patients and 70 patients were treated with chemotherapy with or without RT. Combination chemotherapy in patients with diffuse undifferentiated (DU) or diffuse histiocytic (DH) lymphoma resulted in a significantly higher 6-year survival as compared to patients treated with RT alone. For minimal disease DU/DH patients, the 6-year survival with chemotherapy +/- RT was 96% as compared to 61% with RT alone (P = .03). For extended disease DU/DH patients the 6-year survival with chemotherapy +/- RT was 56% as compared with 18% with RT alone (P = .003). This survival advantage from the initial use of chemotherapy was not seen in any of the other histologic subgroups.

Adolescent↗
PubMed1982

Effects of a prosthetic tongue on vowel intelligibility and food management in a patient with total glossectomy.

Effects of a prosthetic tongue on vowel intelligibility and food management in a patient who underwent total glossectomy are discussed. Results of the vowel intelligibility study indicate improvement from 48% to 64% on the Vowel Rhyme Test with use of the prosthesis. Analyses of listener confusions suggest that the most significant effects of the prosthesis were reductions in height and antero-posterior confusions, and a proportionately larger number of same category errors. Results further reveal that front vowels appear better preserved than back and central vowels, in both prosthesis and nonprosthesis conditions. Effects of the prosthesis on food management are discussed and consideration is given to future prosthesis design and fabrication.

Deglutition↗
PubMed1978

A cyclotron target for the production of radioxenons.

A liquid cesium target has been developed which allows the production and separate identification of the neutron deficient isotopes of xenon. The present report describes irradiations utilizing 34--41 MeV protons to produce millicurie quantities of 127Xe and 129Xem. At higher energies, however, the target could be used without modification to produce xenon isotopes as light as 119.

Cesium↗