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Biomedical subjects

J R Coleman

Publications and source records attributed to J R Coleman.

At least 109 records · Page 6Linked to original sources
PubMed1978

A survey of financial planning models for health care organizations.

This paper describes "what if?" financial planning models developed for health care administrators and financial managers to study and evaluate the economic impact of changes in a health care organization's charge structure, operating policies, reimbursement plans, and services and resources. Models for inpatient and outpatient care systems are presented. The models are described in terms of input, output, and application. An assessment of the state of the art of financial planning and prospects for the future of what if?models are given.

Economics, Hospital↗
PubMed1978

Reconstitution of cells by fusion of cell fragments. I. Myogenic expression after fusion of minicells from rat myoblasts (L6) with mouse fibroblast (A9) cytoplasm.

Rat L6 myoblasts and mouse A9 fibroblasts (HGPRT-) were enucleated by centrifugation of monolayers in the presence of cytochalasin B. Intact cells were reconstituted by Sendai virus mediated fusion of nuclei (minicells) from enucleated rat myoblasts and cytoplasms from enucleated mouse fibroblasts. Colonies arising from proliferating reconstituted cells were distinguished from intact parental cell types on the basis of nuclear and cytoplasmic markers. In five replicate experiments, approx. 70% of all colonies found after fusion were derived from reconstituted cells, 30% arose from intact rat myoblasts contaminating the minicell preparations, and two colonies were identified as hybrids between the parental cell types. Clones derived from reconstituted cells formed myotubes which produced myosin and developed the cross-striated pattern typical of skeletal muscle. The myogenic program of the rat myoblast thus can persist through the enucleation and reconstitution procedures, and is not obviously altered by a period of exposure to mouse fibroblast cytoplasm.

Animals↗
PubMed1978

Ultrastructure and mechanical activity expressed by striated muscle in culture.

Newly devised assay procedures for quantitating the mechanical capabilities of striated muscle fibers grown in cell culture have permitted the correlation of cytological features with the ability to respond mechanically to electrical and chemical stimuli during development. By developmental timing and by physiological characteristics, three distinct mechanical activities can be distinguished: : TWITCH, contracture and wave propagation (escalation). Parallel electron microscopy studies suggest that contracture and escalation require significantly greater internal membrane development than twitch. The assay procedures have revealed that fibers developed in culture from genetically dystrophic chick muscle cells display a heightened electrical threshold for a twich response, but are otherwise similar to normal fibers. Cultured chick fibers, whether of leg or breast origin, exhibit similar ultrastructural and mechanical properties; yet these are different from those of in vivo adult muscle and may represent the avian striated muscle archetype expressed in the absence of innervation. Primary or cell line cultures of rat muscle produce far fewer mechanically active fibers than do avian cell cultures. The influence of culture conditions and cell source, whether avian or mammalian, on the extent of differentiation expressed in culture is so great that our understanding of studies on cultured muscle fibers would benefit from some characterization of both morphological and contractile properties of the fibers being used.

Acetylcholine↗
PubMed1977

Behavioral and hippocampal electrical changes during operant learning in cats and effects of stimulating two hypothalamic--hippocampal systems.

The electrical activity of the dorsal and ventral hippocampus and of the anterior and posterior neocortex is described and illustrated during the development of trained operant behavior in water-deprived cats learning to bar-press for water reward under three operant conditioning schedules: (a) continuous reinforcement; (b) alternating 10 sec periods of reinforcement and non-reinforcement; and (c) mixed reinforcement and non-reinforcement with special auditory and visual cues. In addition, the contrasting effects of 100 c/sec electrical stimulation of the medial and lateral hypothalamic systems upon hippocampal electrical activity and operantly trained behavior are reported. During the early stages of learning to bar-press for water reward, when close attention to the bar and water-well are required, hippocampal electrical activity manifests synchrony (theta rhythm) and neocortical electrical activity is desynchronized. Subsequently, as bar-pressing performance improves and requires little attention to the manipulanda, the pattern of hippocampal and neocortical electrical activity is one of irregular slow waves mixed with low voltage high frequency activity, characteristic of relative inattention and automatic performance. During alternating or mixed reinforcement and non-reinforcement schedules of operant training differential effects are observed during reinforcement and non-reinforcement periods, the latter being characterized generally by lower voltage, mixed low and high frequency activity, except when orienting and shifting of attention occurred with associated theta rhythm bursts. Stimulation of the medial hypothalamic system has a striking inhibitory effect upon bar-pressing for water reward. Bar-pressing ceases for many minutes but its eventually resumed at the pre-stimulation rate. In contrast, stimulation of the lateral hypothalamic system only interrupts bar-pressing for a matter of seconds. Possible causes of these differential effects, and especially the prolonged inhibition of bar-pressing induced by medial hypothalamic stimulation, are discussed.

Animals↗
PubMed1977

A survey of dental care programs offered by "qualified" HMOS.

None of the federally qualified HMOs had a fully prepaid comprehensive dental care program. Less than a third of the plans went beyond the then mandated benefits of the Act, and those that did, only provided the benefits on a fee-for-service basis. The more established plans, with enrollments exceeding 15,000 members, offered a full spectrum of services, and have acceptable levels of utilization. There appears to be a relation between size and services offered and overall utilization of the dental services. The general direction HMOs are taking with regard to the scope of services provided is hard to predict because more than two thirds of the HMOs studied were "transitional" HMOs. The more mature plans appeared to be leaning toward fully comprehensive services; however, only the "basic" dental services then mandated by the Act were covered by prepayment. It is difficult to predict how the nearly 200 HMOs now being planned and developed will integrate dental care into their programs, especially when dental care services are no longer required as a "basic health service". Based upon the cautious approaches used by the HMOs now in operation, it appears safe to assume that comprehensive dental care programs will not be offered by HMOs until they are forced to do so by competing health insurance carriers or a dental program provides them with a competitive edge.

Costs and Cost Analysis↗
PubMed1976

Studies on the organisation of the chicken genome and its expression during myogenesis in vitro.

DNA from the chicken genome was analysed both by isopycnic centrifugation in cesium salt density gradients and by reassociation analysis using hydroxyapatite (HAP) chromatography. Centrifugation in neutral CsCl revealed a single non-Gaussian band skewed toward the heavy side, but no discrete satellite components. In heavy metal (Ag+ or Hg++)-Cs2SO4 gradients, 4-8 satellite bands were revealed, comprising 5-9% of the total DNA. Purification of the satellites and recentrifugation in neutral CsCl demonstrated that 80-90% of this DNA would band in the shoulder, with the remainder in the main band. These satellites can account at most for 30% of the heavy shoulder DNA, thus most of the heavy shoulder DNA must be of lower repetition frequencies. Reassociation analyses of chicken DNA demonstrated that the complexity of the non-repetitive DNA is 9.49 X 10(8) nucleotide pairs, equivalent to about 90% of the haploid genome. Repetitive DNA comprises only 8-10% of the genome and has the following composition, relative to total DNA: 3.7% intermediate repetitive, 1.9% highly repetitive, and 3.9% "zero-time binding" DNA. This unusually low repetitive DNA content may be related to the small genome size of chickens, relative to other vertebrates, and to the presence of many microchromosomes in the chicken karyotype. Total cell RNA extracted from perfusion myoblasts, post-fusion myotubes, and myoblasts grown in BrdU was incubated in large excess with 3H-TdR labelled non-repetitive DNA and the resulting hybrids assayed by HAP chromatography. The amount of non-repetitive DNA represented in the RNA was found to increase from 7-8% in the myoblast stage to 10-11% in myotubes. An even smaller proportion, about 5%, is represented in the RNA of myoblasts prevented from differentiating by growth in BrdU.

Animals↗
PubMed1975

Electron probe analysis of calcium transport by small intestine.

Calcium transport in small intestine of rat and chick has been studied at the cellular level using the electron probe X-ray microanalyzer. Tissues were examined directly after removal as well as after incubation in a calcium solution. In both preparations, discrete calcium localizations were found associated with intracellular and extracellular goblet cell mucus. The in vitro preparations showed calcium in transit across the absorptive epithelium in discrete localizations. Although the primary path of transport was along lateral cell borders, some localizations were found in the cytoplasm in a supranuclear position. The effect of vitamin D depletion and repletion was to decrease and increase, respectively, the number of calcium localizations in transit across the epithelium. These results suggest that calcium is transported while in a sequestered form and indicate that goblet cell mucus plays a role in this transport process.

Aging↗
PubMed1972

Methylxanthine-induced escalation: a propagated wave phenomenon observed in skeletal muscle developing in culture.

Relatively low concentrations of methylxanthines increase spontaneous twitching in cultured muscle fibers; they also cause a second activity, escalation, which is the initiation and undiminished propagation of visible waves. The effect on twitching is abolished by depolarizing concentrations of K(+) or by tetrodotoxin; the effect on escalation is not. Escalation is prevented by removal of external Ca(++) or by the addition of tetracaine.

Aminophylline↗