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Biomedical subjects

M Reed

Publications and source records attributed to M Reed.

At least 19 recordsLinked to original sources
PubMed1995

The C-terminal domain of p53 recognizes DNA damaged by ionizing radiation.

p53 accumulates after DNA damage and arrests cellular growth. These findings suggest a possible role for p53 in the cellular response to DNA damage. We have previously shown that the C terminus of p53 binds DNA nonspecifically and assembles stable tetramers. In this study, we have utilized purified segments of human and murine p53s to determine which p53 domains may participate in a DNA damage response pathway. We find that the C-terminal 75 amino acids of human or murine p53 are necessary and sufficient for the DNA annealing and strand-transfer activities of p53. In addition, both full-length wild-type p53 and the C-terminal 75 amino acids display an increased binding affinity for DNA damaged by restriction digestion, DNase I treatment, or ionizing radiation. In contrast, the central site-specific DNA-binding domain together with the tetramerization domain does not have these activities. We propose that interactions of the C terminus of p53 with damaged DNA may play a role in the activation of p53 in response to DNA damage.

Animals↗
PubMed1995

p53-dependent activation of the mouse MCK gene promoter: identification of a novel p53-responsive sequence and evidence for cooperation between distinct p53 binding sites.

Transcriptional activation by p53 is dependent on the presence of a specific p53 binding site within control sequences of the target gene. One such target gene is the mouse muscle-specific creatine kinase (MCK) gene, which contains a p53 binding site between promoter residues -3182 and -3133 relative to the transcription start site. This DNA sequence is reported to be sufficient to confer p53-dependent activation on the MCK promoter. In contrast to this finding, evidence from promoter deletion studies suggests that sequences in the MCK promoter other than this p53 binding site also permit p53-dependent activation. To investigate this possibility, we have further examined sequences in the MCK promoter required for transcriptional activation by mouse p53. We report here identification of a second p53-responsive sequence within the MCK promoter. This novel sequence is situated between residues -177 and -81, and can confer p53-dependent, position- and orientation-independent activation on a heterologous promoter. Moreover, this sequence can specifically bind mouse and human p53. By promoter deletion studies, we provide evidence that these two elements cooperate to provide high-level, p53-dependent activation of the MCK promoter.

Animals↗
PubMed1991

Obesity and polycystic ovary syndrome.

Our studies show that obese women with polycystic ovary syndrome are more likely to have hirsutism and menstrual disturbances than are lean women with PCOS. The most obvious biochemical differences between obese and lean women with PCOS is that SHBG concentrations are much lower in women with obesity. The SHBG levels are inversely related to insulin, and insulin has been shown to have a direct inhibitory action on SHBG secretion. Other factors, however, may contribute to the mechanism of the increased prevalence of hirsutism and anovulation in obese women with PCOS, such as a direct effect of insulin or increased activity of 5 alpha-reductase in peripheral tissues. Finally we have been able to show that weight reduction of more than 5% is associated with an improved biochemical profile and, importantly, with restoration of fertility.

Endocrine Glands↗
PubMed1991

Expression of rat hepatic lipase in heterologous systems: evidence for different sites for interface binding and catalysis.

Rat hepatic triglyceride lipase was expressed as a bacterial fusion protein and as a secreted protein in eukaryotic cells. The bacterial fusion construct coded for seven amino acids at the N-terminus which are not present in the hepatic lipase cDNA, but otherwise consisted of only the complete mature lipase sequence. Fusion protein was isolated as an insoluble product which did not have lipase or phospholipase activities; it was, however, active as an esterase when solubilized after preparative gel electrophoresis. The fusion protein was used to raise polyclonal antibodies that recognize native rat hepatic lipase and inhibit its activity. For eukaryotic expression, a full-length rat hepatic lipase cDNA clone was inserted into the metallothionein promoter expression vector pMTSV40polyA.Bam. Transfected CHO cells, induced with ZnSO4, secreted an immunoreactive protein of Mr approximately 57,000. A lipase-producing clonal cell line was isolated and used to characterize the enzyme. The protein was purified from serum-free medium by heparin-Sepharose and DEAE-Trisacryl M column chromatography. It was apparently identical to native rat hepatic lipase, with the exception of the conformation of the linkage of the sialic acids which form part of the N-linked carbohydrate complexes. The bacterial fusion protein, the CHO-produced lipase, and native rat hepatic lipase were all inhibited by phenylmethylsulfonyl fluoride, implying that they function catalytically as serine esterases. Substrate competition studies indicated that the esterase and lipase activities use the same active site; thus, the major defect in the fusion protein was probably in triglyceride substrate binding. These results suggest that interface binding and catalysis occur at different sites in the protein.

Animals↗
PubMed1990

The effect of hypoxia on angiotensin-stimulated release of PGI2 from the splanchnic bed.

The effect of hypoxia on splanchnic angiotensin II (AII)-stimulated prostaglandin (PG) release was examined in male rats. The superior mesenteric artery was cannulated and perfused in vitro with physiologic buffer at a pO2 of 460 or 60 torr. Splanchnic vessels were perfused isolated (SV) or in continuity with the small intestine (SV + SI). AII (10-300 ng) was infused as bolus injections. Quantitative analysis of SV + SI effluent by bioassay indicated the predominant PG released was PGI2. Quantitative analysis by radioimmunoassay confirmed PGI2 as the major PG released from the SV and SV + SI following AII stimulation. Relative hypoxia significantly decreased AII-stimulated release of PGI2 from the SV, and only modestly from the SV + SI. These data demonstrate two splanchnic sources of AII-stimulated vasodilator PG synthesis, the SV and SV + SI, with the SV more sensitive to relative hypoxia. Diminished release of splanchnic vascular (SV) vasodilator PGI2 may be of importance in AII-mediated splanchnic vasoconstriction seen in hypoxia and shock.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

A simple protocol for the screening and preliminary identification of antibodies to human IgA using unpurified proteins in the passive haemagglutination test.

Experiments have shown that suitably diluted, unpurified IgA paraprotein sera can be substituted for chemically purified IgA proteins in the passive haemagglutination test for the detection of anti-IgA antibodies. The substitution of unpurified IgA paraprotein was made possible by the enhanced serological activity obtained by pre-heating the unpurified immunoglobulin preparations at 56 degrees C for 60 min. Using a small screening panel of suitably coated tanned red cells, various population groups were investigated for the presence of anti-IgA antibodies. Results were similar to those obtained by other workers using purified IgA preparations in the passive haemagglutination test.

Antibodies, Anti-Idiotypic↗
PubMed1990

From food basket to food security. The food factor in nutritional surveillance.

One important indicator of nutritional surveillance is the one devoted to monitor food security. The experience toward the development of one of such indicators is presented. This includes the development of a food basket, defined as the group of foods that meet the characteristics such as is now consumed by important population segments of the community; it contributes a substantial portion of the calories and proteins purchased, and is responsible for an important proportion of the food budget. The concept implies a dynamic food basket, the quantities of which are calculated in a way that simulates the behavior of the consumer and the best nutrition knowledge. For this purpose we use linear program techniques. A measure of the risk of being unable to buy the foods needed for a family is presented, and is used as a proxy for food security risk. In the appendix, the mathematical expressions of the model used for a linear program is also presented.

Colombia↗
PubMed1989

Effect of cytoskeletal geometry on intracellular diffusion.

A method is presented for determining the retardation of diffusion of particles inside cells owing to cytoskeletal barriers. The cytoskeletal meshwork is treated as a repeating periodic two-dimensional or three-dimensional lattice composed of elements of given size, shape, and spacing. We derive an analytic expression for the diffusion coefficient relative to that of the cytosol. This expression is evaluated by solving numerically an appropriate boundary-value problem for the Laplace equation. For the two-dimensional case, e.g., diffusion in a membrane, the results are quantitatively similar to those obtained by Saxton (1987. Biophys. J. 52:989-997) using Monte Carlo methods. The three-dimensional results are quantitatively similar to experimental results reported by Luby-Phelps et al. (1987. Proc. Natl. Acad. Sci. USA. 84:4910-4913) for the diffusion of dextran and Ficoll particles in Swiss 3T3 cells. By accounting for geometrical factors, these results allow one to assess the relative contributions of geometrical hindrance and of binding to the cytoskeletal lattice from measurements of intracellular diffusion coefficients of proteins.

Cytoskeleton↗
PubMed1989

Intubation with low-dose atracurium in children.

The objective of this study was to compare intubating conditions and neuromuscular effects using smaller doses of atracurium (0.25 mg/kg and 0.3 mg/kg) with the recommended dose of 0.4 mg/kg for intubation in children anesthetized with halothane, N2O and oxygen undergoing strabismus repair. All patients (10 in each group) had good or excellent intubating conditions at 80% depression of twitch height [T1 of train-of-four (TOF) stimulation]. Mean times to intubation were 2.6 +/- 0.2 minutes following 0.25 mg/kg and 2.2 +/- 0.2 minutes following 0.3 mg/kg. These times were significantly longer (P less than 0.05) than the mean intubation time of 1.5 +/- 0.2 minutes following 0.4 mg/kg. Mean times to recovery, defined as times from injection of atracurium to return of T1 of TOF to 10%, 25%, and 95% of control measurements, were significantly shorter with the smaller doses. Atracurium at these low doses may provide an alternative to succinylcholine for intubating children during halothane anesthesia for surgical procedures lasting 20-30 min.

Anesthesia↗
PubMed1988

A new autosomal recessive lethal chondrodystrophy with congenital hydrops.

Two sibs, the offspring of consanguineous parents, presented with severe short-limb dwarfism and distinct chondro-osseous, radiologic, and histologic appearance. The first sib presented at 30 wk with severe hydrops following fetal death; the second was detected by ultrasonography at 20 wk. Radiologic abnormalities included an unusual "moth-eaten" appearance of the markedly short long bones, bizzare ectopic ossification centers, and marked platyspondyly with unusual ossification centers. Marked extramedullary erythropoiesis was present in both fetuses, and chondro-osseous histology was characterized by marked disorganization of tissue with interspersed masses of cartilage, bone, and mesenchymal tissue. These sibs appear to have a distinct previously unreported autosomal recessive skeletal dysplasia, which can present as hydrops fetalis.

Adult↗
PubMed1988

VP-16 + adriamycin vs. adriamycin alone in advanced adenocarcinoma of the breast, phase II, a randomized trial: a Southwest Oncology Group Study.

One hundred twenty-two patients with advanced adenocarcinoma of the breast were randomized to receive adriamycin (AD) alone or a combination of VP-16 plus lower dose adriamycin (VAD). The patients were stratified to good and poor risk. The starting dose (day 1) of AD was 60 mg/m2 for good risk and 45 mg/m2 for poor risk. The starting dose of the VAD combination for the good-risk patient was VP-16, 75 mg/m2 daily x 5 plus adriamycin 35 mg/m2. The poor-risk dose for VAD was VP-16, 50 mg/m2 daily x 5 plus adriamycin, 30 mg/m2 on day 1. The total dose of AD was 450 mg/m2 on both arms. The patients who were on the VAD arm continued on VP-16 maintenance. Both arms were repeated every 21 days. There were 54 evaluable patients on the adriamycin arm and 52 evaluable patients on the VAD arm. Both arms were similar with regard to age, menopausal status, performance status, and prior hormonal therapy. More hematologic toxicity was seen in the adriamycin arm. Complete responses were observed on both arms, three (5%) with adriamycin and three (5%) with combination. Eleven (19%) and ten (18%) partial responses were observed with the adriamycin and VP-16 plus adriamycin, respectively. AD produced more stable disease than VAD (41% vs. 29%). Complete responses were seen only in the good-risk patients. Time to progression was delayed on the combination arm (P = 0.02). The survival in both arms was similar. The addition of VP-16 to adriamycin does not offer an important clinical advantage.

Adenocarcinoma↗
PubMed1988

A statistical approach to the discrimination of the cranial form.

In a study of lateral cephalographic dimensions, their multivariate statistical analysis was shown to discriminate between patients with gross cranial anomalies and controls exhibiting no abnormal morphology. Although the degree of discrimination depended upon the group of dimensions included in the analysis, discrimination was more consistent than when compared using univariate statistical techniques. As cephalographic dimensions combine both size and shape parameters together, however, the interpretation of such contrasts must await more specific analytic techniques development.

Cephalometry↗
PubMed1988

Surgical intensive care unit pneumonia.

With use of an objective numerical rating system for the assessment of the presence or absence of pneumonia on a chest x-ray film, 81 patients in the surgical intensive care unit with positive sputum cultures were assigned to either colonization (C; 39 patients) or pneumonia (P; 42 patients) groups. Respiratory failures preceding the first positive sputum culture and hepatic and/or renal failure were more frequent in the P group. Escherichia coli and Pseudomonas species, as well as polymicrobial sputa, were more common in the P group. Positive blood or pleural cultures with the same organism found in the sputum were noted in 10 of 11 P patients and only 3 of 10 C patients. Broad-spectrum antibiotic therapy directed at all sputum pathogens decreased mortality in the P group but not in the C group. We conclude that an objective rating system for chest x-ray diagnosis provides a reasonable method for separating patients with pneumonia from those with colonization. We recommend antibiotic therapy directed at all sputum pathogens in patients in surgical intensive care units. For such therapy to be successful, however, diagnostic criteria must be precise and exclude patients with colonized pathogens.

Bacteria↗
PubMed1987

Blood donation by the elderly. Clinical and policy considerations.

At present, healthy potential blood donors older than the age of 66 years often leave the donor pool for reasons of age alone, despite the fact that this demographic group is growing, is a potentially willing source of blood products, and constitutes the cohort with highest per capita use of blood and its derivatives. There is no clinical or physiological rationale for this. We performed a controlled study to measure the feasibility and safety of blood donation by healthy elderly donors aged 66 years and older, compared with a younger cohort aged 55 to 65 years of age. A study group of prior donors aged 66 years and older and a control group of prior donors between the ages of 50 and 65 were sent letters inviting them to donate blood. The volume donated did not differ between the two groups. In the older group, there were eight immediate reactions, seven mild and one moderate. The control population experienced seven immediate reactions, six mild and one severe. We conclude that it is both clinically feasible and efficient to recruit healthy prior donors older than the age of 66 years for blood donation. As a group, this population is potentially able to donate large volumes of blood and do so without any difference in immediate or short-term reactions. Further study of hemodynamic variables as more objective markers of safety is needed.

Adult↗
PubMed1987

Cardiac embryogenesis: a three-dimensional approach.

In order to aid students in the understanding of cardiac embryogenesis, seven three-dimensional fiberglass models depicting stages eleven to eighteen of cardiac embryogenesis, and one model of a mature heart were constructed. The details of these models, and a review of cardiac embryogenesis is presented. The results we have had with these models in the teaching of cardiac embryogenesis to medical students, cardiac technologists, and nurses have been encouraging, and this approach to teaching is highly recommended.

Heart↗