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R Downing

Publications and source records attributed to R Downing.

At least 37 records · Page 2Linked to original sources
PubMed1997

Detection of genetically diverse human immunodeficiency virus type 1 group M and O isolates by PCR.

A panel of 136 genetically diverse group M and 5 group O adult isolates from outside the United States and Europe were evaluated by PCR with the Roche AMPLICOR HIV-1 test, a modified version of the AMPLICOR HIV-1 test, and a new primer pair/probe system. Detection of some of these isolates was less efficient with the AMPLICOR HIV-1 test; however, the assay was significantly improved by reducing the sample input and lowering the annealing temperature. The new primer pair/probe set detected 140 of 141 isolates, including the 5 group O isolates that were not detected with either of the AMPLICOR HIV-1 test formats.

Adult↗
PubMed1996

Herpesvirus-like DNA sequences detected in endemic, classic, iatrogenic and epidemic Kaposi's sarcoma (KS) biopsies.

The identification of Kaposi's sarcoma (KS) clusters in sub-equatorial Africa (endemic KS, AKS) and the high frequency of KS in sexually transmitted AIDS (epidemic KS, EKS), have previously suggested a role for infectious agents in the etiopathogenesis of KS. The recent identification of herpesvirus (HHV)-like DNA sequences in one case of EKS and their detection in > 90% of all tested EKS, prompted us to determine the prevalence of these viral sequences in all types of KS, such as AKS, EKS, classic KS (CKS) and iatrogenic KS (IKS). The presence of herpesvirus(HHV)-like DNA sequences has been examined in 61 KS skin tumors obtained from Greece, Italy, USA, Uganda and Kenya. All KS types (100%) were positive by polymerase chain reaction (PCR) and Southern-blot analysis, while 5 out of 6 (83%) and 4 out of 7 (57%) uninvolved autologous skin biopsies from AKS and CKS patients, respectively, were positive for HHV-like sequences. All samples from non-KS patients were negative, i.e. 17 human biopsies from healthy individuals or patients affected by other pathologies, 5 human cell lines and 15 peripheral blood mononuclear cells (PBMC) from HIV-positive subjects. These results suggest that HHV-like sequences play a major role in the pathogenesis of this neoplasm.

DNA, Viral↗
PubMed1994

Presence of multiple genetic subtypes of human immunodeficiency virus type 1 proviruses in Uganda.

DNA sequences encoding the C2-V3 regions or the C2-V5 regions of the surface glycoprotein gp120 of the human immunodeficiency virus type 1 (HIV-1) were amplified by the polymerase chain reaction (PCR) from peripheral blood mononuclear cells obtained in 1990/1992 from 20 infected Ugandans. The PCR-amplified DNA was cloned into a phagemid vector and between 1 and 12 clones from each provirus were sequenced. The Ugandan proviruses were aligned into four subtypes (A, B, C, and D) by phylogenetic analysis of consensus nucleotide sequences for the C2-V3 regions. Analysis of the deduced amino acid sequences of the C2-V3 regions by a maximum parsimony program gave a similar phylogenetic relationship. The data indicated that phylogenetic analysis of nucleotide and/or amino acid sequences from the C2-V3 regions is a reliable method of subtype determination. The consensus amino acid sequence of the subtype A and D proviruses were almost identical to those of the Albert et al. group B and group A proviruses, respectively. The deduced amino acid sequences of the C2-V5 regions of six of these proviruses showed considerable diversity both between patients and within patients. The region varied in length between 234 and 243 amino acids and included deletions and repetitions, particularly in the V4 region.

Adult↗
PubMed1993

Antidepressants for the treatment of generalized anxiety disorder. A placebo-controlled comparison of imipramine, trazodone, and diazepam.

OBJECTIVE: The current study examines whether antidepressants, contrary to current thinking, are safe and effective treatments for generalized anxiety disorder (GAD) not complicated by depression or panic disorder. DESIGN: Randomized, double-blind, placebo-controlled, flexible-dose, 8-week treatment study comparing imipramine hydrochloride (mean maximum daily dose, 143 mg), trazodone hydrochloride (255 mg), and diazepam (26 mg). PATIENTS: Two hundred thirty patients with a DSM-III diagnosis of GAD in whom major depression and panic disorder has been excluded, and who had a Hamilton Anxiety Scale total score of at least 18. SETTING: Seventy-five percent of patients were treated in family practice settings in the community, with the remainder treated in psychiatric practices, either academic or private. RESULTS: Patients treated with diazepam showed the most improvement in anxiety ratings during the first 2 weeks of treatment, with somatic symptoms being most responsive. From week 3 through week 8 trazodone achieved comparable, and imipramine somewhat better, anxiolytic efficacy when compared with diazepam, with psychic symptoms of tension, apprehension, and worry being more responsive to the antidepressants. Among completers, moderate to marked improvement was reported by 73% of patients treated with imipramine, 69% of patients treated with trazodone, 66% of patients treated with diazepam, but only 47% of patients treated with placebo. Overall, patients treated with antidepressants reported a higher rate of adverse effects than diazepam-treated patients, but attention rates were the same across all treatments. CONCLUSIONS: The results of the study need replication, but suggest a potentially important role for antidepressants, particularly imipramine, in patients suffering from GAD.

Adult↗
PubMed1992

Platelet accumulation after laser angioplasty--a scintigraphic assessment.

Indium 111-labeled platelet scintigraphy was performed to evaluate platelet deposition in response to different levels of Nd:YAG laser/thermal energy. A dose-related increase in platelet deposition was observed. In clinical studies after laser-assisted balloon angioplasty, intense platelet deposition was observed in 2 patients who subsequently developed clinical arterial thrombosis. The pathogenesis of reocclusion appears, however, to be more complicated and ill understood. The authors suggest further extensive studies incorporating several parameters in the evaluation of the pathogenic factors involved in reocclusion after laser angioplasty. Such studies should also consider the role of arterial injury produced by the balloon catheter after laser-assisted balloon angioplasty.

Aged↗
PubMed1991

Labelled antibody imaging in pancreatic cancer, cholangiocarcinoma, chronic pancreatitis and sclerosing cholangitis.

Pancreatic and biliary carcinomas are difficult to differentiate clinically from their benign counterparts, chronic pancreatitis and sclerosing cholangitis. Immunohistochemical differences in CEA expression have previously been demonstrated in these conditions. We have therefore investigated the use of a monoclonal anti-CEA antibody (11-285-14) in distinguishing between these conditions in vivo. Twenty-five patients with these four conditions underwent radioimmunolocalisation studies. Diagnosis was confirmed by laparotomy and biopsy (n = 21), CT scanning (n = 1) or ERCP (n = 3). Positive images were obtained in 11/12 pancreatic cancers and 2/3 biliary tumours. However, 4/8 cases of chronic pancreatitis and 1/2 cases of sclerosing cholangitis also had positive images. This high false positive rate suggests that antibody imaging is unable to differentiate reliably between benign and malignant pancreatico-biliary conditions.

Adenoma, Bile Duct↗
PubMed1991

Isolation of islets of Langerhans from the weanling pig.

A simple method for the isolation of porcine islets of Langerhans is described. The technique, based on sequential collagenase digestion and density gradient separation through Percoll at unit gravity, produces islets which secrete insulin in response to glucose stimulation in static incubation, show bi-phasic release of insulin when perifused with 16 mM glucose, and can be maintained in culture for six weeks.

Animals↗