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Biomedical subjects

R Petersen

Publications and source records attributed to R Petersen.

At least 73 records · Page 4Linked to original sources
PubMed1988

The Drosophila hsp70 message is rapidly degraded at normal temperatures and stabilized by heat shock.

When heat-shocked Drosophila cells are returned to normal temperatures, heat-shock protein (HSP) synthesis is repressed and normal protein synthesis is restored. The repression of HSP70 synthesis is accompanied by the selective degradation of its mRNA. We have engineered cells to produce a modified hsp70 mRNA that behaves exactly as the wild-type message. That is, it is stable during heat shock but degraded during recovery when protein synthesis returns to normal. When this message, placed under the control of the metallothionein promoter, is induced at normal temperatures it is rapidly degraded, with a half life of 15-30 min. Apparently, the hsp70 message is inherently unstable. During heat-shock, degradation of the message is suspended; during recovery degradation is restored.

Animals↗
PubMed1988

Prediction of the risk of hereditary retinoblastoma, using DNA polymorphisms within the retinoblastoma gene.

Using molecular cloning, we earlier isolated the "retinoblastoma gene"; mutations or deletions at this locus are associated with the hereditary predisposition to some human cancers, especially retinoblastoma and osteosarcoma. To develop diagnostic tests for such a predisposition, we identified restriction-fragment-length polymorphisms (RFLPs) within the retinoblastoma gene and tested their usefulness in predicting the risk of cancer in 20 families with members who had hereditary retinoblastoma. We were able to make predictions in 19 of the 20 kindreds. In 18 kindreds, we demonstrated a consistent association of marker RFLPs with the mutation predisposing to retinoblastoma. In the 19th kindred, there may be a lack of cosegregation of the DNA polymorphisms within the gene and the site of the mutation predisposing to retinoblastoma. However, there is uncertainty about the clinical diagnosis of the retinal lesion in a key member of this kindred; if the lesion is not a retinoblastoma, there is no discrepancy between the DNA polymorphisms and the retinoblastoma trait. We conclude that it is feasible and clinically useful to use these DNA polymorphisms to determine the risk of cancer.

Alleles↗
PubMed1987

In vivo administration of anti-CD4 monoclonal antibody prolongs survival in longtailed macaques with experimental allergic encephalomyelitis.

The in vivo administration of monoclonal antibody (mAb) to the CD4 antigen associated with helper T cells has been successful in prolonging the survival of nonhuman primates with experimental allergic encephalomyelitis (EAE). EAE was induced in 17 outbred longtailed macaques (Macaca fascicularis) by inoculation of homologous myelin basic protein (BP) in complete Freund's adjuvant (CFA). Treatment was begun at the onset of clinical signs. Eleven animals were treated with anti-CD4 mAb Leu3a (eight) or OKT4a (three). Of the six control animals, two received anti-CD8 mAb (Leu2a), and four were treated with saline. Specific T- and B-cell subsets which have been implicated in the development of EAE were monitored throughout the course of the disease by one- and two-color immunofluorescence (IF). The monkey anti-BP antibody and anti-mouse immunoglobulin (IgG) responses were measured by enzyme-linked immunoassay (ELISA) techniques, as were the levels of free-circulating murine IgG. The nature of the infiltrating lymphocytes in the brain was evaluated histologically post mortem. Our results indicate that anti-CD4 mAb can prolong survival and in some cases completely reverse the clinical appearance of the disease; however, relapses did occur. Treatments with Leu3a or OKT4a anti-CD4 mAbs reversed the ongoing depletion of CD4+ and CD8+ cells caused by the development of EAE and appeared to reduce the size and degree of inflammation in brain lesions. These treatments did not induce immunologic tolerance to mouse IgG since all of the anti-CD4-treated animals produced high titers of anti-mouse IgG antibodies. Treatment with Leu2a (anti-CD8) had no effect on the development of EAE. These results suggest that CD4+ cells are important to the pathogenesis of EAE in macaques and that manipulation of this subset with monoclonal antibodies may provide effective treatment of human demyelinating disease.

Animals↗
PubMed1986

Comparison of calculated estimates and laboratory analysis of food offered to hospitalized eating disorder patients.

Estimation of caloric intake is an integral part of a comprehensive research/treatment program for patients with eating disorders at the National Institute of Mental Health. Caloric intakes are estimated by recording daily food intake and calculating calories using food exchange lists and food composition tables. To evaluate the validity of that method, caloric intake estimates were compared with laboratory analysis data over a 15-day period. The estimations for daily caloric intake in comparison with the laboratory analysis data were underestimated by a mean percent difference of 2.4%. The estimated carbohydrate and fat intakes were overestimated by 4.5% and 5.4%, respectively. The estimated protein intake was underestimated by 1.1%. The data suggest that estimates of caloric intake based on food exchange lists and food composition tables are within an acceptable range of error and, therefore, represent a practical approach to estimating caloric intake for patients hospitalized with an eating disorder.

Anorexia Nervosa↗
PubMed1984

Homozygosity of chromosome 13 in retinoblastoma.

We studied the frequency of chromosome 13 homozygosity in tumor tissue obtained directly from eyes harboring retinoblastomas. The data indicate that approximately half of all retinoblastomas are homozygous for large portions of 13q, that the homozygosity occurs in vivo and not as an event secondary to culture of the tumor cells, that chromosome 13 homozygosity is not correlated with the degree of histopathologic differentiation of the tumor, and that the homozygosity occurs in both sporadic and hereditary retinoblastomas. The development of chromosome 13 homozygosity may represent a fundamental event in the oncogenesis of a considerable number of retinoblastomas. This finding may have implications for the genetic counseling of patients with hereditary retinoblastoma. It may also be important in understanding the mechanism of oncogenesis of other tumors, especially hereditary tumors.

Alleles↗
PubMed1983

Effects of verapamil on coronary hemodynamic function and vasomobility relative to its mechanism of antianginal action.

The effect of intravenous verapamil on systemic and coronary hemodynamic function was studied at cardiac catheterization in 12 patients with coronary artery disease. Verapamil was administered as a 2-minute bolus (0.145 mg/kg) followed by an infusion (0.005 mg/kg/min). Cardiac output and coronary sinus blood flow were measured by thermodilution techniques. Caliber of the large coronary arteries and of diseased segments was determined from the coronary angiogram using a computer-assisted method. Verapamil reduced mean arterial pressure 14% (p less than 0.001), systemic vascular resistance 21% (p less than 0.01), and stroke work index 16% (p less than 0.001). Coronary vascular resistance decreased 24% (p less than 0.01) with a small increase in coronary sinus blood flow (+13%, difference not significant [NS]). Myocardial oxygen consumption determined in 5 patients showed no significant change with verapamil. Luminal area in 39 coronary lesions was measured in the "normal" portion of the diseased segment and at its maximal constriction, and an estimate of flow resistance in the stenosis was computed. Overall, 50% of "normal" and of diseased coronary segments dilated significantly with verapamil. Stenosis dilation resulted in an average 14% reduction (p less than 0.01) in estimated flow resistance. In 8 patients, the luminal changes (n = 27) induced by sublingual nitroglycerin were compared with those induced by verapamil. Nitroglycerin induced a significantly greater increase in coronary caliber in both normal and diseased segments; estimated stenosis flow resistance decreased 28% with nitroglycerin compared with 14% with verapamil (p less than 0.01). Thus, verapamil moderately dilates the systemic and coronary small vessel resistance bed without apparently increasing myocardial metabolic demand. Furthermore, verapamil mildly dilates large coronary conductance vessels in both "normal" and diseased segments, although significantly less than does nitroglycerin.

Aged↗