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Biomedical subjects

M Holmes

Publications and source records attributed to M Holmes.

At least 109 records · Page 6Linked to original sources
PubMed1986

Effects of 6-hydroxydopamine on the hypothalamo-pituitary-adrenocortical axis.

Female rats were treated with two intraventricular injections each of 350 micrograms 6-hydroxydopamine (6-OHDA) and used for experiment 4 or 14 days later. The response to laparotomy, as assessed by subsequent in vitro corticosterone release, was unaffected by the drug, but that to the smaller stress of a skin cut was significantly reduced. Both fast and delayed feedback responses to corticosterone administration were still evident in 6-OHDA-treated animals. When determined 14 days after treatment, hypothalamic concentrations of epinephrine (E) and norepinephrine (NE) were reduced by 46 and 84%, respectively. There was no significant change in content of immunoreactive corticotropin-releasing factor (CRF-41). The acetylcholine-stimulated release of CRF bioactivity from control hypothalami incubated in vitro was significantly inhibited by E or NE, with E being at least 10 times more potent on a molar basis. This effect of NE was enhanced in hypothalami removed from 6-OHDA-treated rats, complete inhibition of acetylcholine-stimulated release of CRF being produced by 0.6 nM NE, as opposed to 6.0 nM for untreated controls. At the level of the anterior pituitary gland, tissue content of adrenocorticotropin (ACTH) was unaffected by treatment, but that of luteinizing hormone (LH) in the same tissues was significantly increased. The corticotrophic response of fragments of the gland incubated or perifused in vitro to hypothalamic extract, CRF-41, arginine vasopressin or E was reduced. In contrast, the response of the tissue to gonadotropin-releasing hormone (GnRH) added in vitro was not significantly affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1986

Neuroimaging in refractory partial seizures: comparison of PET, CT, and MRI.

We compared the results of x-ray CT, magnetic resonance imaging (MRI), and positron emission tomography (PET) using 18F 2-deoxyglucose in 36 patients with partial seizures. Seventeen patients had localized epileptic discharges on surface EEG. MRI showed an abnormality in 9, CT in 4, and PET in 13 of 14 patients who had the test. Nineteen patients had nonlocalizing EEG discharges. MRI showed an abnormality in 11, CT in 10, and PET in 8 of 12. MRI is more sensitive than CT in detecting structural lesions underlying PET hypometabolism.

Adolescent↗
PubMed1984

Teaching clinical decision making.

Clinical judgment has traditionally been left to be acquired chiefly through personal experience and conversations with experienced practitioners. Given the explosion of knowledge and technology of recent years, a more systematic approach to managing information has become increasingly important. Ethical issues, both of a social and more individual nature, also increasingly demand attention. This paper describes one effort to address these problems through medical education. A three quarter pre-clinical course was revised to incorporate decision analysis and ethical analysis. The approach, results and problems of the two-year-old innovation are discussed, and general recommendations are offered.

Bioethical Issues↗
PubMed1984

Physicians' judgments about estrogen replacement therapy for menopausal women.

A study was undertaken to determine how physicians decide when to prescribe estrogen. Twenty-five gynecologists and 25 family physicians responded to case histories and a questionnaire regarding estrogen administration. There was no difference in mean probability of prescribing, 0.42 for gynecologists and 0.40 for family physicians. Endometrial cancer risk and vasomotor symptom severity were significant factors in prescribing judgments; osteoporosis risk and current treatment status were not. In linear regression analysis the constant, not factor weights, were significantly related to each physician's overall likelihood of prescribing and to the individual's self-characterization as prescriber or nonprescriber. Most physicians indicated that estrogen reduces fracture risk, and that progestin reduces cancer risk. Physicians' responses to cases were not consistent with these stated beliefs about estrogen effects.

Estrogens↗
PubMed1983

Merkel cell distribution in the epidermis as determined by quinacrine fluorescence.

The Merkel cell distribution in the basal epidermis of amphibian and mammalian skin was visualized in whole mounts by means of quinacrine fluorescence. In most cases only the isolated epidermis was viewed following dermal-epidermal separation. Tadpole tentacles contained numerous quinacrine fluorescent cells (QFC) 25-40 microns apart. Groups of 2-4 QFC were found around the gland openings in frog epidermis but not in salamander epidermis where the QFC were irregularly scattered 40-100 microns apart. In the rat, ring-like clusters of a few to 200 or more QFC were distributed across the basal epidermis of trunk skin (at touch domes or Haarscheiben), eyelid, ear, nose, and whisker pad. The ridged (glabrous) skin of the nose and footpad contained numerous QFC that appeared to follow the contours of the epidermal ridges. The isolated external root sheath of rat vibrissae contained an upper cylindrical cuff of several hundred QFC; enzymatic dissociation of these sheaths produced individually isolated as well as small clusters of fluorescent and non-fluorescent cells. Electron-microscopic examination of several of these cells confirmed that the fluorescent ones are Merkel cells, identified by the presence of characteristic dense-cored granules; in contrast, the non-fluorescent cells lack this ultrastructural feature.

Ambystoma↗
PubMed1983

Two nonallelic tRNAiMet genes are located in the p23 leads to q12 region of human chromosome 6.

Two nonallelic human tRNAiMet genes were assigned to chromosome 6 by filter hybridization of DNA from human-rodent somatic cell hybrids by using probes containing unique sequences from the regions flanking each tRNAiMet gene. These unique sequence probes thus allowed each tRNAiMet gene to be analyzed individually in cell hybrids. Both tRNAiMet genes segregated in the hybrid cells with the chromosome 6 enzyme markers, soluble malic enzyme and the mitochondrial form of superoxide dismutase, and also with a karyotypically normal chromosome 6. By using hybrid clones containing translocations that divide chromosome 6 into five segments, both tRNAiMet genes were assigned to the p23 leads to q12 region. These results raise the possibility that other tRNAiMet genes may be syntenic with the two described in this study and illustrate the utility of using unique flanking sequences to identify members of a multigene family.

Alleles↗
PubMed1983

Differences among black, Hispanic, and white people in knowledge about long-term care services.

This article provides data obtained through telephone interviews with 1,608 white, black, Mexican American, or Puerto Rican respondents. The study was designed to measure differences among ethnic groups in knowledge and attitudes toward long-term care services and the extent to which knowledge and attitudes affect service use. Across all groups, there is less knowledge about long-term, community-based care than institutional services. The extent of knowledge about services is limited among all groups, but especially among Puerto Ricans. There are marked differences among groups in attitudes toward services. Minority groups are far more likely to perceive care of the elderly as a family responsibility and to stress the importance of ethnic factors in service delivery. Despite differences among groups, knowledge and attitudes are less directly related to use of services than is activity limitation. This may be because only a very small proportion of the respondents had any experience with service use.

Black or African American↗
PubMed1980

Cell division of cycle of Bacillus subtilis: evidence of variability in period D.

In Bacillus subtilis the deoxyribonucleic acid content and the extent of cell division during inhibition of chromosome replication increased as a function of the average cell mass, independent of the growth rate. At each growth rate, mass, deoxyribonucleic acid, and residual division varied in different cultures. The variation is consistent with a large variability in the D period. At growth rates higher than 1.5 doublings per h at 37 degrees C, the change in D accounts for the growth rate dependence of the mass and deoxyribonucleic acid content.

Bacillus subtilis↗
PubMed1979

The effect of cyproheptadine on the release of corticotrophin releasing factor.

The effect of cyproheptadine was tested on the neurotransmitter-induced release of corticotrophin releasing factor (CRF) from the rat hypothalamus in vitro. It was found that cyproheptadine inhibited both acetylcholine and 5-hydroxytryptamine-induced release of CRF. Cyproheptadine did not interfere with the ACTH releasing ability of CRF. These results suggest that cyproheptadine reduces the high circulating levels of ACTH in some patients suffering from Cushing's disease and Nelson's syndrome by inhibiting CRF secretion.

Acetylcholine↗
PubMed1979

Estimation of lung volumes from chest radiographs using shape information.

The cross-sectional shapes of the chest and its contained structures have been assessed in post-mortem anatomical sections and from computerised tomographic scans in living subjects. These shapes are described by simple equations that can be used to increase the accuracy of measuring lung volumes from chest radiographs. Radiographic estimates of total lung capacity, using the equations, were compared with plethysmographic and single-breath helium dilution measurements in 35 normal subjects. The postures commonly used for taking chest radiographs were found, on average, to decrease total lung capacity (TLC) and to increase residual volume by about 200 ml when compared with the sitting positions used for the other two measurements (studies made in 18 of the subjects). After correction for this effect, the radiographic estimates of TLC, which measure the displacement volume of the lung, exceeded the plethysmographic estimates of contained gas volume by a mean of 720 ml, which was taken as the volume of tissue, blood, and water in the lungs. The single-breath dilution estimates of TLC fell short of the plethysmographic values by a mean of 480 ml, taken as the volume of contained gas that was inaccessible to helium in 10 seconds. The tomographic studies suggested that the radiographic technique of measuring lung displacement volumes has an accuracy of +/- 210 ml. The method is rapid and simple to use and has intra- and inter-observer variabilities of less than 1% and less than 5% respectively.

Helium↗
PubMed1978

Use of active sorting and retrieval strategies as a facilitator of recall, clustering, and sorting by EMR and nonretarded children.

The ability of 60 EMR and 60 nonretarded children to acquire and retain a sorting and retrieval strategy designed to be facilitative of recall and clustering was examined. All subjects were given a baseline task and, based on their performance, were assigned to one of three groups: experimental, practice, and control. The experimental group received a multi-session training procedure that consisted of instructing the subjects to arrange the stimuli in conceptual arrays, to name individual stimuli and the superordinates to which the stimuli belong, and to count the number of stimuli in each superordinate. The practice group was presented with the same stimuli but received no training. The control group received only the baseline and criterion measures. Analyses of data showed superior performance by the experimental group on measures of short- and long-term recall, clustering, and sorting.

Association↗