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Biomedical subjects

R C Dunlap

Publications and source records attributed to R C Dunlap.

17 recordsLinked to original sources
PubMed1994

Role of endothelium-derived relaxing factor in hindlimb reactive and active hyperemia in conscious dogs.

We tested in conscious dogs whether endothelium-derived relaxing factor (EDRF) mediates hindlimb reactive and active hyperemia. Hindlimb reactive hyperemia was observed in response to release of a 1-min occlusion of the terminal aorta, and in separate studies, hindlimb active hyperemic responses to graded dynamic (treadmill) exercise were observed before and after inhibition of EDRF production [NG-nitro-L-arginine methyl ester (L-NAME); 5 mg/kg iv)]. At rest, L-NAME significantly increased mean arterial pressure (MAP) from control levels (100.6 +/- 6.2 vs. 125.0 +/- 7.3 mmHg) and significantly decreased heart rate (HR) (94.1 +/- 4.6 vs. 65.7 +/- 3.8 beats/min), terminal aortic blood flow (TAQ) (0.51 +/- 0.01 vs. 0.33 +/- 0.03 l/min), and terminal aortic vascular conductance (TAC) (5.2 +/- 0.4 vs. 2.7 +/- 0.1 ml.min-1.mmHg-1). L-NAME also significantly reduced the hindlimb hyperemia induced by intra-arterial acetylcholine (5 micrograms/kg). During reactive hyperemia L-NAME significantly reduced both the duration and maximal increase in TAC (16.2 +/- 1.6 vs. 10.4 +/- 0.8 s and 24.5 +/- 3.3 vs. 21.0 +/- 3.1 ml.min-1.mmHg-1, respectively). During graded exercise, MAP was significantly higher and HR significantly lower at each work load after L-NAME. During mild exercise, TAQ was significantly lower after L-NAME, whereas at higher work loads, L-NAME had no significant effect on TAQ. TAC was significantly reduced at each work load after L-NAME, but the difference from control remained constant with increasing work load; L-NAME caused a constant offset in TAC during graded exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Propagation and properties of Kaposi's sarcoma-derived cell lines obtained from patients with AIDS: similarity of cultured cells to smooth muscle cells.

Cells derived from Kaposi's sarcoma (KS) were propagated in vitro using conditions which resulted in elimination of contaminating fibroblasts and the emergence of homogeneous cell populations which morphologically resembled smooth muscle cells and had neoplastic characteristics. In long-term culture, they differentiated into large ribbon-like cells with longitudinal fibrillarity of their cytoplasm. These fibrils stained red by Masson trichrome staining, and were reactive with antibodies to desmin. Dense bodies typical of myoblasts were observed in some cells by electron microscopy. The cells did not form capillary structures like endothelial cells, they lacked Weible-Palade bodies, and did not express the blood-clotting Factor VIII-related antigen or receptors for the lectin Ulex europaeus agglutinin I. They did express four other antigens, however, in common with endothelial cells. The cells did not form tumors in athymic nude mice; however, they formed colonies in soft agar, manifested tumor-like growth on muscle organ cultures, and were invasive in an artificial basement membrane invasion assay. The results indicate that a component of KS is closely related to leiomyoblasts and and has neoplastic properties.

Acquired Immunodeficiency Syndrome↗
PubMed1977

Correlation of laboratory studies with clinical responses to A/New Jersey influenza vaccines.

The large, uniformly performed clinical investigations with influenza A/New Jersey vaccines provided an opportunity to correlate results of laboratory tests of vaccine with human reactivity and antibody responses. These vaccines were given to large numbers of subjects under code, and significant differences in immunogenicity and reactivity were observed in unprimed individuals. A single, relatively large dose of intact virus was more immunogenic and reactive than split-virus vaccines in unprimed subjects. Differences in immunogenicity and reactivity in unprimed subjects correlated with the amount of intact virus in the vaccines (measured by column chromatography or electron microscopy) and with the amount of viral hemagglutinin in the vaccine (measured by immunodiffusion), but not with the number of chick cell-agglutinating units.

Adolescent↗
PubMed1976

Comparative trial of influenza vaccines. I. Immunogenicity of whole virus and split product vaccines in man.

Groups of about 100 persons aged 6 to 88 years were given 1 of 6 commercially prepared whole virus or split-product bivalent (A/England-B/Mass) influenza vaccines and 6 weeks later were given 1 of 5 monovalent (B/Hong Kong) vaccines. Hemagglutination-inhibiting (HI) antibody titers in serum specimens taken 6 and 12 weeks after inoculation were compared to those obtained before immunization. Overall antibody responses in all groups were adequate, yielding HI titers that are associated with relatively good levels of protection from infection. No differences were noted among the vaccines in their ability to boost pre-existing antibody. The tributyl phosphate (TBP) split-product vaccine, however, induced significantly lower homologous seroconversion and geometric mean antibody titers (GMT) to A/England and heterologous antibody titers to A/Aichi in persons without pre-existing antibody than did equivalent whole virus vaccines. Both the TBP and the ether-treated monovalent B/Hong Kong vaccines also induced lower heterologous GMT's to B/Mass in initially seronegative individuals. These data agree with previous observations that the primary response to influenza and other viral vaccines prepared from disrupted virions results in lower levels of antibody than does that to equivalent whole virus preparations. Studies are underway to determine whether the lesser immune response induced by these vaccines in seronegative persons is the result of smaller amounts of antigen in such preparations or because the antigen may be processed less efficiently by humoral or cellular immune mechanisms.

Adolescent↗
PubMed1976

Comparative trial of influenza vaccines. II. Adverse reactions in children and adults.

Commercially prepared zonally and chromatographically purified bivalent (A/England-B/Mass) and monovalent (B/Hong Kong) inactivated influenza vaccines were given to 438 individuals 6-33 years old. The vaccines had been examined for antigen content by chick cell agglutination (CCA) tests and electron microscopic particle count determinations. Endotoxin and pyrogen content were determined by limulus amebocyte lysate (LAL) and rabbit pyrogenicity assays; and egg-associated protein contamination was estimated by total protein and single radial immunodiffusion assays. Although great differences (10-200-fold) were found in the amount of endotoxin or pyrogen in the vaccines, no significant differences were found in the febrile responses they induced. Both bivalent and monovalent vaccines induced fever of greater than or equal to 38 C at a rate of approximately 3 1/2-4% above background. The febrile responses were most frequent at 24 hours after inoculation and a higher rate was observed in children than adults. Local reactions consisting of tenderness, erythema or induration were seen in from 20-57% of the recipients and also were unrelated to the pyrogenic or host-derived materials in the vaccines. Adults had higher local reaction rates than children and some vaccines containing larger amounts of viral antigen induced significantly higher rates of reactivity than did vaccines containing smaller amounts of antigen. Although 37-51% of all recipients experienced either a local and/or febrile reaction to influenza immunization, the reactions were in general mild and would not consitute a significant disadvantage in the immunization of children over 6 years and adults to prevent influenza infection and its sequelae.

Adolescent↗
PubMed1976

Acute and chronic infection of human lymphoblastoid cell lines with measles virus.

Several human continuous lymphoblastoid cell lines (LCL) having T or B characteristics were infected with low and high passage strains of measles virus. All of the cell lines were susceptible to one or the other or to both strains of measles virus with the production of typical syncytial giant cells and released cell-free infectious virus into the supernatant medium. There was no consistent pattern of susceptibility of LCL with either T or B characteristics to infection by measles virus. Viral induced cytolysis of the lymphoblastoid cells in many of the lines was marked, but in the LCL that could be maintained over longer periods of time, a state of chronic, less cytolytic and persistent infection could be established. The infection was characterized by the production of moderate amounts of cell-free infectious virus for up to 4 1/2 months after initial infection with little change in the number of viable cells in culture. Long-term low multiplicity of infection (MOI) experiments demonstrated that the cell-free infectious virus was being produced only by a small number of cells, but the majority of cells in culture contained measles antigen that was in a cell-restricted, noninfectious, or defective form. Electron microscopic examination of the chronically infected cells demonstrated that many of them contained aggregates of hollow tubular intranuclear nucleocapsids whose "stripped" appearance was in marked contrast to the larger granular intracytoplasmic nucleocapsids found during earlier stages of infection. It is theorized that the persistent infection of LCL may serve as a model in understanding the immune mechanisms which permit latent and chronic measles infection in man.

Acute Disease↗
PubMed1970

Virus particle content of smallpox vaccines.

Calf lymph smallpox vaccines contain too much extraneous debris for an accurate assessment of their virus particle content. The process of partial purification of the vaccine utilizing enzymatic digestion by chymotrypsin, subtilisin, and collagenase solubilized enough debris to permit electron microscopic virus particle count. Enzyme treatment did not degrade or destroy the virus nor did it reduce the infective titer. Commercial vaccines studied ranged in virus content from 1.89 x 10(9) to 1.09 x 10(11) virus particles/ml. The pocking efficiencies on the chorioallantoic membrane of some of these vaccines varied from 200 to 1,200 virus particles per pock-forming unit.

Agar↗