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Biomedical subjects

John Rutherford

Publications and source records attributed to John Rutherford.

6 recordsLinked to original sources

HIV-1 Env-specific cytotoxic T-lymphocyte responses in exposed, uninfected Kenyan sex workers: a prospective analysis.

The prospective significance of HIV-specific cytotoxic T lymphocyte (CTL) responses in highly exposed, persistently seronegative populations is unknown. In 1996-1997 we screened for CTL responses against HIV clade B Env in 39 recently enrolled Kenyan female sex workers, and followed these women prospectively. Annual HIV incidence was 5.8%. CTL were independently associated with age and recent HIV-1 exposure,but were not prospectively associated with protection in a multivariable model that included HIV-1 exposure and duration of sex work.

Adult↗

Direct visualization of nitric oxide release by liver cells after the arrest of metastatic tumor cells in the hepatic microvasculature.

BACKGROUND: Our previous studies have shown that the injection of B16F1 melanoma cells into the mesenteric vein can induce the rapid local release of nitric oxide (NO) in the liver, causing apoptosis of the melanoma cells in the liver sinusoids and inhibiting the subsequent formation of hepatic metastases. In this study, we have investigated the distribution and cellular source of NO in this model. MATERIALS AND METHODS: In situ liver perfusion was established in both wild-type (wt) and endothelial nitric oxide synthase knockout (eNOS KO) C57BL/6 mice. A specific fluorescent NO probe, 4,5-diaminofluorescein diacetate (DAF-2 DA) (5 micromol/L), was perfused into the portal venous system to label the liver tissue. Then, a MitoTracker Orange labeled B16F1 melanoma cell suspension (2 x 10(6) cells/ml) was injected through a portal vein catheter by a peristaltic pump. Images of the liver tissue were taken by confocal microscopy from a selected area to determine the cellular source of NO. For quantification, the fluorescence intensity of this area was measured over time by Fluoview software. RESULTS: Diaminotriazolofluorescein (DAF-2T) fluorescence (indicating NO generation) was detected in hepatic parenchymal cells located in the periportal region in both wt C57BL/6 and eNOS KO C57BL/6 mice and was intensified by increased flow rate in the portal venous system. The B16F1 cells arrested in the periportal sinusoids, corresponding to zone 1 of the hepatic acinus. DAF-2T fluorescence was expressed by both sinusoidal lining cells and hepatocytes at the site of tumor cell arrest. The fluorescence intensity of these cells increased approximately 2-fold over a time of 500 s. In contrast, there was no increase in the fluorescence intensity of the sinusoidal lining cells and hepatocytes in mice perfused with buffer or in eNOS KO mice perfused with B16F1 cells. CONCLUSION: This study demonstrates that NO is produced by hepatic parenchymal cells mainly located in the periportal zones and that the arrest of the B16F1 melanoma cells causes an eNOS-dependent local burst of NO by the sinusoidal lining cells and hepatocytes in the periportal areas.

Animals↗

Impact of cirrhosis on the development of experimental hepatic metastases by B16F1 melanoma cells in C57BL/6 mice.

Metastases rarely occur in human livers with cirrhosis in clinical studies. We postulated that this phenomenon would also occur in experimental cirrhosis. Cirrhosis was established in C57BL/6 mice by carbon tetrachloride (CCl(4)) gastrogavage. B16F1 melanoma cells were injected into the mesenteric vein to induce hepatic metastases. Contrary to our postulate, there was greater than 4-fold increase in metastasis in animals with cirrhosis compared to controls. Intravital videomicroscopy showed that the hepatic sinusoids were narrower and more tumor cells were retained in the terminal portal vein (TPV) in cirrhotic livers. Immunohistochemistry demonstrated that the expression of vascular adhesion molecules was significantly increased in cirrhosis. Using confocal microscopy and the fluorescent nitric oxide (NO) probe 4,5-diaminofluorescein diacetate, a significantly lower level of NO release was detected in livers with cirrhosis both in basal conditions and after tumor cell arrest. Eight hours after mesenteric vein tumor cell injection, the percentage of apoptotic tumor cells in the sinusoids was 17% +/- 2% in livers with cirrhosis and 30% +/- 5% in normal livers. More mitotic and Ki-67 labeled tumor cells were seen in livers with cirrhosis. In conclusion, the changes in architecture and adhesion molecule expression in livers with cirrhosis may cause more tumor cells to arrest in the TPV. Lower levels of NO production may reduce apoptosis of B16F1 cells in livers with cirrhosis. As a result, these changes may promote the growth of metastasis in this cirrhotic model.

Animals↗

Careful physical examination is essential in the preoperative assessment of children for dental extractions under general anesthesia.

BACKGROUND: Physical examination is routinely carried out for the preoperative assessment of children, but is it of value in day stay community dental surgery? METHODS: A prospective survey of new diagnoses made on children presenting for community dental extractions and compared with children having nondental surgery. RESULTS: Five of 216 children for dental extractions were seen with new diagnoses made, with a variety of conditions including patent ductus arteriosus, aortic stenosis, ventricular septal defect and obstructive sleep apnea. No new diagnoses were made in 294 nondental children in the same period. CONCLUSIONS: Physical examination provides a useful adjunct to the history in children undergoing community dental extraction. There is potentially significant morbidity undiagnosed in apparently fit children presenting for dental surgery.

Adolescent↗

Development of functional human monoclonal single-chain variable fragment antibody against HIV-1 from human cervical B cells.

A panel of novel recombinant single-chain variable fragment (scFv) antibody against human immunodeficiency virus type-1 (HIV-1) was isolated and characterized. We generated human scFvs using RNA harvested from cervical B lymphocytes of Kenyan prostitutes who are highly exposed to HIV-1, but remain persistently seronegative. The variable regions of the heavy (VH) and light (VL) chain antibody genes were selected as hybrids using guided-selection with the VL and VH, respectively, of a derivative of IgGb(12) using the phagemid vector pComb3X. IgGb(12) is a previously well-characterized HIV-1 neutralizing human monoclonal antibody (MAb). One of the hybrid scFv, IgA6/4L, neutralizes HIV-1 infectivity in in vitro cell culture assay. The cervical VH and VL chain antibody genes were connected by a DNA linker and subcloned in pComb3X. The cervical scFv clones were functional in recognizing HIV-1 gp120 by enzyme-linked immunosorbant assay (ELISA) and on cells in flow cytometry. Whole IgGb(12) does not inhibit binding of clones IgA6/5k nor IgA6/30lambda to gp120, which suggests that they bind different epitopes. Nucleotide sequence analysis of the cervical scFv show the clones are unique and reveal interesting characteristics of human cervical V gene pools. This work demonstrates, for the first time, cloning of a functional scFv MAb to a sexually transmitted disease pathogen from local cervical B-cell pools in exposed humans.

Amino Acid Sequence↗