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Biomedical subjects

J R Coleman

Publications and source records attributed to J R Coleman.

At least 73 records · Page 4Linked to original sources
PubMed1987

Contiguous organization of nitrogenase genes in a heterocystous cyanobacterium.

The organization of the three structural nitrogen fixation (nif) genes that encode nitrogenase (nif K and nif D) and nitrogenase reductase (nif H) have been examined in a number of cyanobacteria. Hybridization of Anabaena 7120 nif gene probes to restriction endonuclease-digested genomic DNA has shown (a) that cyanobacteria incapable of N(2) fixation have no regions of DNA with significant homology to the three nif probes, (b) that Pseudanabaena sp., a nonheterocystous cyanobacterium, has a contiguous nif KDH gene cluster, and (c) that in contrast with other heterocystous cyanobacteria, Fischerella sp. has a contiguous nif KDH gene cluster.

Journal Article↗
PubMed1987

Molecular cloning of a recA-like gene from the cyanobacterium Anabaena variabilis.

A recA-like gene isolated from the cyanobacterium Anabaena variabilis was cloned and partially characterized. When introduced into Escherichia coli recA mutants, the 7.5-kilobase-pair plasmid-borne DNA insert restored resistance to methyl methanesulfonate and UV irradiation, as well as recombination proficiency when measured by Hfr-mediated conjugation. The cyanobacterial recA gene restored spontaneous but not mitomycin C-induced prophage production. Restriction analysis and subcloning yielded a 1.5-kilobase-pair Sau3A fragment which also restored methylmethane sulfonate resistance and coded for a 38- to 40-kilodalton polypeptide when expressed in an in vitro transcription-translation system.

Cloning, Molecular↗
PubMed1986

Resting and high-frequency evoked 2-deoxyglucose uptake in the rat inferior colliculus: developmental changes and effects of short-term conduction blockade.

Development of resting and high-frequency-evoked metabolic patterns in the central nucleus of the inferior colliculus (ICC) in rat was investigated using the 2-deoxyglucose (2-DG) method. The effects of early short-term acoustic deprivation were studied by unilateral blockade of the external auditory meatus on postnatal day 12. Quantitative and qualitative analyses were performed on 2-DG uptake in 5 regional sectors of ICC. Adult resting ICC uptake is robust and exhibits regional differentiation with the ventromedial region preferentially labelled. At 17 days of age, resting uptake is substantially lower and regionally more uniform than in the adult. This age-dependent change is likely a function of the immature stage of neuronal and cochlear development at 17 days. Unilateral 50 kHz stimulation in the adult results in bilaterally enhanced 2-DG incorporation in ventromedial ICC, with a discrete band of elevated uptake along the contralateral ventromedial border. 50 kHz stimulation evokes ventromedial banding in the contralateral, but not ipsilateral, ICC of undeprived 17-day-olds, though at a much reduced level relative to the adult. Following monaural conduction blockade from 12 to 17 days of age, stimulation through the reopened deprived ear elicits a band of uptake along the lateral ICC border, oblique to the normal tonotopic gradient. Cochlear mechanisms may account for modified patterning of high-frequency-evoked 2-DG uptake in ICC subsequent to conductive hearing loss during a period of elevated susceptibility to experiential factors.

Age Factors↗
PubMed1986

Transcription of the histone H5 gene is not S-phase regulated.

Levels of the tissue-specific linker histone H5 are elevated in mature erythroid cells as compared with levels in dividing cells of the same lineage. We examined levels of H5 mRNA in relation to the cell cycle in early erythroid cells transformed by avian erythroblastosis virus to determine whether the gene for this unusual histone is S-phase regulated. Northern blotting analyses revealed that during the cell cycle steady-state levels of H5 mRNA remained relatively constant in contrast to levels of the major core and H1 mRNAs which increased approximately 15-fold during S phase. In vitro pulse-labeling experiments involving nuclei isolated from synchronized cells at various stages of the cell cycle revealed that transcription of the H5 gene was not initiated at any particular stage of the cell cycle but was constitutive. In contrast, transcription of the H2A gene(s) initiated in early S phase, was present throughout the DNA replicative phase, and was essentially absent in G1 and G2 phases.

Alpharetrovirus↗
PubMed1985

Binaural interactions in cortical area AI of cats reared with unilateral atresia of the external ear canal.

Binaural interactions were recorded in auditory cortical (AI) neurons of anesthetized adult cats that had unilateral atresias created shortly after birth by surgically ligating and cutting one external ear canal. At the time of the recording experiment, the atresia and associated debris were removed and tones were delivered to both tympanic membranes via a sealed and calibrated acoustic system. The majority of neurons recorded were in the cortex ipsilateral to the previously occluded ear. Thresholds for monaural stimulation of either the operated or unoperated ear were within normal range although thresholds to stimulation of the previously operated ear tended to occupy the upper end of the normal distribution. Monotonic and nonmonotonic spike count-vs-intensity functions derived from responses to monaural stimulation of the atretic ear were indistinguishable in their shape from those recorded in normal cats. All binaural classes were represented in our sample in proportions similar to those reported in cats with two normal ears. The forms of the functions relating spike count to interaural intensity differences and interaural phase differences were essentially the same as those seen in normal animals. The main binaural deficit observed under these conditions was a shift in the interaural intensity difference to which an AI neuron was most sensitive. The intensity needed for a stimulus to the atretic ear to participate in the binaural response was as much as 50 dB higher than that at the opposite normal ear in contrast to the nearly equal SPLs required for binaural interactions in cats with two ears intact. It was suggested that elevated thresholds at the previously operated ear could account for much of the shift observed.

Action Potentials↗
PubMed1985

Gingival and bacterial plaque response to instrumentation, oral hygiene instruction and nutritional therapy.

Thirty-three male subjects participated in a study to examine the effect of supplements of multiple vitamins and minerals, local therapy (periodontal instrumentation and oral hygiene instruction) and a combination of both on gingival inflammation and bacterial plaque formation. Subjects were given either multivitamin and mineral supplements or placebos on a double-blind basis for 21 days. On Day 7, the mandibular incisors were instrumented, and each subject was instructed in brushing and flossing. Observations were taken at Days 0, 7 and 21. There was a significant (P = 0.004) effect from micronutrient supplementation at Day 7 on the gingival index but no significant effect on the plaque index. On Day 21 there was no statistical superiority noted for the supplemented group in respect to either the gingival or plaque index, although the gingival index approached significance (P = 0.062).

Adult↗
PubMed1985

The changing marketplace for medical care.

The rapid growth of HMOs, PPOs, and large medical groups; the shift to DRGs for hospital payments; the expected use of DRG payments for physician care; and a projected oversupply of physicians promise to keep competition for primary care dollars on the rise. As this competition intensifies, the role of physician assistants in the health care system may change--cost realities should step up the value of PAs in the care delivery system. To take full advantage of the new environment. PAs must understand just how the shifting health care marketplace will affect their profession.

Delivery of Health Care↗
PubMed1984

Extinction of muscle-specific properties in somatic cell heterokaryons.

In studies of gene regulation using somatic cell fusion techniques, the analysis of heterokaryons circumvents several problematic aspects of the more traditional approach utilizing proliferating hybrid cells. We have analyzed the expression of muscle specific properties in heterokaryons between muscle and nonmuscle cells in order to investigate whether differentiating cells contain regulatory factors that repress the expression of alternative developmental pathways. Heterokaryons and cybrids were derived from polyethylene glycol-mediated fusion of differentiated mononucleate chicken myocytes with mouse melanoma cells, mouse melanoma cytoplasts, chicken fibroblasts, or other chicken myocytes. Our results demonstrate that fusion of a myocyte with a nonmyogenic cell generally results in extinction of muscle-specific properties in the immediate fusion product. Myocyte X melanoma heterokaryons ceased to express the skeletal muscle forms of myosin, desmin and creatine kinase, reinitiated DNA synthesis, and showed a loss of spontaneous fusion competence within 96 hr after their formation. Although chicken myocyte X mouse melanoma heterokaryons showed extinction of muscle specific properties, they continued to synthesize protein and to incorporate [3H]hypoxanthine, presumably due to the continued production of constitutive chicken HPRT. That presence of the melanoma nucleus was required for extinction to be observed was demonstrated by the continued expression of muscle proteins in cybrids between chicken myocytes and melanoma cytoplasts. Significantly, heterokaryons between chicken myocytes and chicken fibroblasts also exhibited extinction of muscle proteins, demonstrating for the first time that extinction is not restricted to fusions in which at least one parental cell type was derived from an established cell line. Our results strongly support the notion that extinction reflects cell-type specific gene regulatory mechanisms operative during development.

Animals↗
PubMed1984

Expression of myoblast and myocyte antigens in relation to differentiation and the cell cycle.

Cell cycle parameters and expression of myoblast and myocyte antigens were investigated during exponential growth and during the differentiation phase of rat L8( E63 ) myoblasts by an integrated approach involving microspectrophotometry with DNA fluorochromes, [3H]thymidine autoradiography, and immunofluorescent staining with monoclonal antibodies. In addition to the majority of cells which are recruited into myotubes, two distinct populations of mononucleate cells were resolved in cultures of rat myoblasts undergoing differentiation. These mononucleate cells consist of (1) a population of proliferating cells with a prolonged G1 transit time; (2) a population of non-proliferating cells which remain arrested in G1 for more than 72 h. The latter group was examined with respect to the expression of two marker antigens recognized by two monoclonal antibodies: antibody B58 reacts with a macromolecular component present in undifferentiated myoblasts but not in mature myotubes, and antibody XMlb reacts with a muscle-specific isoform of myosin. All four possible combinations of expression of these antigens by single cells were found: B58 +XM1b -, B58 +XM1b +, B58 - XM1b -, and B58 - XMlb +. The implication of these findings with respect to the transition from the proliferative to the differentiative phase of myogenesis is discussed.

Animals↗
PubMed1984

Biosynthesis of carbonic anhydrase in Chlamydomonas reinhardtii during adaptation to low CO(2).

The unicellular green alga Chlamydomonas reinhardtii synthesizes carbonic anhydrase in response to low levels of CO(2) (i.e., air levels of CO(2)). This enzyme, localized predominantly in the periplasmic space of the alga (or associated with the cell wall), is an important component of the machinery required for the active accumulation of inorganic carbon by C. reinhardtii and the saturation of ribulose-1,5-bisphosphate carboxylase at low extracellular carbon concentrations. We have begun to examine the synthesis and compartmentalization of carbonic anhydrase in C. reinhardtii. The monomeric species associated with carbonic anhydrase activity is synthesized as a precursor on 80S cytoplasmic ribosomes. This precursor can be detected immunologically in the profiles of translation products when a reticulocyte lysate, cell-free system is primed with poly(A)-RNA from either air-grown C. reinhardtii or cells shifted from growth on 5% CO(2) to air for 12 hr. It is not synthesized when the in vitro system is primed with poly(A)-RNA from CO(2)-grown algae. Since translatable RNA for the polypeptide responsible for carbonic anhydrase activity was only present in cells that experienced low levels of CO(2), the adaptation process either involves the regulation of transcription of the carbonic anhydrase gene (and perhaps other genes involved in adaptation) or the post-transcriptional processing of the messenger RNA. Furthermore, the appearance of the mature polypeptide associated with carbonic anhydrase activity in the periplasmic space of C. reinhardtii is inhibited by tunicamycin, an antibiotic that prevents core glycosylation of polypeptides on the endoplasmic reticulum. Together, these results suggest that the biosynthesis of this extracellular algal enzyme involves the translation of mRNA for the carbonic anhydrase monomer on ribosomes bound to the endoplasmic reticulum, the cleavage of a signal sequence during transport of the nascent polypeptide into the lumen of the endoplasmic reticulum, and subsequent glycosylation events prior to export across the plasmalemma.

Journal Article↗
PubMed1984

Identification of Extracellular Carbonic Anhydrase of Chlamydomonas reinhardtii.

We have examined the induction of carbonic anhydrase activity in Chlamydomonas reinhardtii and have identified the polypeptide responsible for this activity. This polypeptide was not synthesized when the alga was grown photoautotrophically on 5% CO(2), but its synthesis was induced under low concentrations of CO(2) (air levels of CO(2)). In CW-15, a mutant of C. reinhardtii which lacks a cell wall, between 80 and 90% of the carbonic anhydrase activity of air-adapted cells was present in the growth medium. Furthermore, between 80 and 90% of the carbonic anhydrase is released if wild type cells are treated with autolysin, a hydrolytic enzyme responsible for cell wall degradation during mating of C. reinhardtii. These data extend the work of Kimpel, Togasaki, Miyachi (1983 Plant Cell Physiol 24: 255-259) and indicate that the bulk of the carbonic anhydrase is located either in the periplasmic space or is loosely bound to the algal cell wall. The polypeptide associated with carbonic anhydrase activity has a molecular weight of approximately 37,000. Several lines of evidence indicate that this polypeptide is responsible for carbonic anhydrase activity: (a) it appears following the transfer of C. reinhardtii from growth on 5% CO(2) to growth on air levels of CO(2), (b) it is located in the periplasmic space or associated with the cell wall, like the bulk of the carbonic anhydrase activity, (c) it binds dansylamide, an inhibitor of the enzyme which fluoresces upon illumination with ultraviolet light, (d) antibodies which inhibit carbonic anhydrase activity only cross-react with this 37,000 dalton species.

Journal Article↗
PubMed1984

Heart rate and sleep time: their relationship with growth and adiposity in male infants.

In a clinical trial based on the direct relationship between heart rate activity and energy expenditure during awake and asleep states, 21 healthy 18-month-old infants had their heart rate monitored over a period of 24 h and correlated with their nutritional intake, growth parameters, and measurements of adiposity (fat cell size and skinfold thickness). Infants with higher 24-h and asleep heart rates had smaller fat cells (r = -0.50) and skinfold thickness (abdominal r = -0.70, suprailiac r = -0.80, triceps r = -0.67). Infants with higher relative weight had higher heart rates during awake periods (r = 0.60). Infants sleeping for longer periods had higher weight gain velocity from birth (r = 0.51) and higher relative weight (r = 0.54). This study demonstrates the heart rate activity and duration of sleep are related to growth and adipose tissue deposition during infancy.

Adipose Tissue↗
PubMed1983

Analysis of myogenesis by somatic cell hybridization. II. Retention of myogenic competence and suppression of transformed properties in hybrids between differentiation competent and incompetent rat L6 myoblasts.

This study describes the characteristics of hybrids between two closely related rat myoblast lines, which differ both in the ability to express their program of differentiation and in the expression of neoplastic properties. Myogenic, nonneoplastic L6J1-S cells were hybridized with nonmyogenic, neoplastic L6J1-N1 cells. Six hybrid clones were isolated and expanded for analysis of myogenic competence, and four of these clones were also evaluated for parameters of transformation, including tumorigenicity, ability to clone in agar, and surface fibronectin. In addition to our analysis of isolated clones, we also assessed myogenic differentiation in colonies representing 226 early hybrid clones. Results of all these analyses demonstrate that the myogenic phenotype is retained and that the tumorigenic/transformed phenotype is suppressed in the hybrids. Furthermore, our results indicate that when the programs for myogenesis and neoplastic transformation are confronted within a single cell, they are expressed as mutually exclusive alternatives. In contrast to these results on myogenic X nonmyogenic L6 hybrids, it has been reported that isolated clones of A9 X L6 exhibited extinction of myogenic competence and retention of transformed properties. We have evaluated myotube formation in over 300 early hybrid clones between A9 and either diploid or subtetraploid L8 rat myoblasts. Our results demonstrate that all of these hybrid clones exhibit extinction regardless of the ploidy of the myoblast parent, and they further indicate that extinction is not a consequence of chromosome loss. These results support the conclusion that in A9 X L6 hybrids, the nonmyogenic, transformed phenotype is dominant.

Animals↗
PubMed1983

A computerized MIS to support the administration of quality patient care in HMOs organized as IPAs.

All federally qualified HMOs must develop and implement quality assurance programs for monitoring the quality of care, the quality of services, and the costs of inpatient and ambulatory care. Such quality assurance programs are diverse and vary in administrative structure, criteria, review procedures, feedback, and decision making. This paper describes a computerized quality assurance reporting system operating in an HMO organized as an IPA network. The design and use of various MIS reports containing information on inpatient utilization and costs, physician office visits and physician practice patterns, physician productivity, physician referral patterns and costs, and the health problems of members are presented. The importance of these MIS-generated reports on the operations of IPA medical groups and the HMO and how they are used by medical directors, HMO management, and committees charged with quality assurance responsibilities is also included.

Computers↗
PubMed1983

Analysis of myogenesis by somatic cell hybridization: III. Myogenic competence of hybrids derived from rat L6 myoblasts and mouse primary fibroblasts and myoblasts.

Hybrid cells derived from rat L6 myoblasts and mouse primary fibroblasts (M x F hybrids), as well as those derived from rat L6 myoblasts and mouse primary myoblasts (M x M hybrids), were examined for their ability to engage in myogenesis as judged by muscle fiber formation plus the expression of skeletal muscle myosin and creatine kinase (CK). Of 172 primary hybrid colonies scored, 59% were myogenic in the M x F fusion and 97% exhibited muscle fiber formation in the M x M fusion. Individual hybrid clones from each cross were isolated, expanded and analyzed for myogenic capabilities as well. All three M x M and all ten M x F isolated clones exhibited preferential elimination of mouse chromosomes. Nonetheless, all were capable of fusing spontaneously and of elaborating skeletal muscle myosin and CK. The three M x M hybrids expressed only MM-CK whereas nine out of ten M x F hybrids produced all three CK isoenzymes (MM, MB, BB). These results suggest that M X M hybrids express CK patterns reminiscent of the rat L6 parental cells while M X F hybrids apparently mimic mouse muscle fiber CK patterns. Various models are discussed which address these phenomena.

Animals↗