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Biomedical subjects

C Morrison

Publications and source records attributed to C Morrison.

At least 109 records · Page 6Linked to original sources
PubMed1996

Motivation to participate, exercise affect, and outcome behaviors toward physical activity.

Recently researchers have focused attention on understanding the relationship between motivation to participate and affective states associated with adherence to exercise and psychological outcomes of participation. It was hypothesized that intrinsic motivation toward an activity will heighten the associated positive affect, thereby leading to increased participation and higher perceived competence and satisfaction. The presently devised models tested the above hypothesis with 130 college students enrolled in psychology classes. They were asked to complete the Motivation for Physical Activity Measure, the Sport Enjoyment Questionnaire, and general demographic questions assessing adherence to exercise and perceived competence and satisfaction. Partial support for these path models was shown as intrinsic motivation was a predictor of affect and perceived competence and satisfaction, while extrinsic motivation predicted adherence for men only. These results provide a model to enhance the understanding of exercise-related behavior in the general population and the study of the relationship of motivation with affect toward exercise.

Adolescent↗
PubMed1995

A model for magnetization transfer in tissues.

Magnetization transfer in several tissues is measured and successfully modeled using a two-pool model of exchange. The line shape for the semi-solid pool is characterized by a superLorentzian and the liquid pool by a Lorentzian. The tissues investigated were white and gray matter, optic nerve, muscle, and liver. All tissues the authors studied are characterized by the same model but differ in the parameter values of the model. Blood and cerebral spinal fluid (CSF) were also investigated. The two-pool model with a Lorentzian line shape for both the semi-solid and liquid pools modeled the magnetization transfer in blood. In CSF, as expected, there is no measurable exchange of magnetization. The T2B associated with the semi-solid pool was short (approximately 10 microseconds) for all tissues indicating a fairly rigid semi-solid pool. In addition characterization of the line shape as superLorentzian indicates molecules such as integral membrane proteins or lipids in membranes are likely molecules participating in the exchange. Conversely, in blood large globular proteins are indicated due to the Lorentzian nature of the semi-solid pool and a T2B approximately 300 microseconds.

Animals↗
PubMed1995

Modeling magnetization transfer for biological-like systems using a semi-solid pool with a super-Lorentzian lineshape and dipolar reservoir.

Magnetization transfer is modeled as an exchange between a liquid pool and a semi-solid pool where the semi-solid pool has, in addition to the Zeeman reservoir, a dipolar reservoir. The lineshape for the liquid pool is characterized by the usual Lorentzian, whereas the semi-solid pool is characterized as a super-Lorentzian. Three systems were investigated: (1) a membrane mixture of a phosphatidylcholine lipid (POPC) and cholesterol; (2) lyophilized white matter at eight solid concentrations ranging from 1 to 24%; and (3) fresh white matter. In all systems, this model fitted the experimental data well with the effect of the dipolar reservoir being most important for the membrane mixture. For the tissue, the dipolar reservoir is not required and the two-pool model with a single Zeeman reservoir for the semi-solid spins characterizes the experimental data equally well.

Animals↗
PubMed1995

In vitro biocompatibility testing of polymers for orthopaedic implants using cultured fibroblasts and osteoblasts.

The biocompatibility of two polymers for potential use as orthopaedic implant materials in an isoelastic hip prosthesis was investigated. The interactions of polyetheretherketone (PEEK) and epoxy resin polymers (with and without carbon fibre reinforcement) with both fibroblasts and osteoblasts were tested using cell protein, intracellular reduced glutathione (GSH), leakage of lactate dehydrogenase and the MTT assay as indices of cellular cytotoxicity. The epoxy resin polymer was slightly cytotoxic to and inhibited the growth rate of fibroblasts (as assessed by total cell protein), and depleted GSH in both cell types. In contrast, the PEEK material did not display overt signs of cytotoxicity and, in fact, increased osteoblast cell protein content. This suggests that, of these two materials, PEEK would be the one of choice for development of an isoelastic implant and, in view of its stimulatory effect on osteoblast protein content, it may encourage ingrowth of bone around the prosthesis and thus minimize joint loosening.

3T3 Cells↗
PubMed1995

Divalproex sodium and other medications for headache following craniotomy for acoustic neuroma.

Multiple pharmacologic agents were used in attempt to relieve a constant and severe headache in a 47-year-old patient following craniotomy for removal of an acoustic neuroma. Possible etiologies for the unremitting headache are presented. Response to various pharmacologic agents are listed and discussed. During the postoperative course of two surgeries on this patient, it was possible to propose an etiology for the headache by analyzing the mechanisms of each therapeutic agent, along with the patient's response. Divalproex sodium provided complete relief, suggesting the headache is attributable to cell membrane instability.

Anticonvulsants↗
PubMed1995

Maternity services for drug misusers in England and Wales: a national survey.

A postal questionnaire was sent to the 213 National Health Service maternity units in England and Wales to identify their current involvement with drug misusers. The response rate was 89.5%. Data indicated that only 29% had formal links with their local drug agency. Child protection case conferences were automatically convened in 52%, and 57% routinely admitted babies to high dependency areas. Twenty-seven per cent of the units did not offer hepatitis B screening to pregnant women, and 32% did not offer hepatitis B prophylaxis to babies whose mothers were infected. Local Health purchasing authorities should ensure that their providers are offering appropriate services to pregnant drug misusers in order to encourage such women to seek help without fear of discrimination. Liaison between health care agencies should be encouraged and areas with low levels of drug misuse should receive help with formulating policies, and training, from units with more experience.

England↗
PubMed1994

The impact of the PCR plateau phase on quantitative PCR.

The quantitative use of the polymerase chain reaction (PCR) is often compromised by the variability of the amplification. The most useful system for quantitation by PCR involves the use of controls which are almost identical to the target and which can be amplified using the same primers as the sequences of interest. In this paper, we use a model system consisting of differently sized targets amplifiable with varying primers to demonstrate the effects of the plateau phase of PCR on quantitation by PCR. This model confirms two commonly observed results: (i) when varying amounts of a single target are amplified, a constant maximum level of product is obtained and (ii) coamplification of different concentrations of different targets results in retention of the initial proportions. The inherent contradiction in these results is examined by replacement of the key elements of the reaction including enzyme, dNTPs or primers, none of which have an effect on the plateau. Pyrophosphate is found to exert no inhibitory effect on the reaction, nor does the exonuclease action of the enzyme cause the plateau. Levels of amplification attained during amplification are both theoretically and empirically defined as being insufficient to lead to the plateau due to competition between self-annealing of product DNAs and primer binding. We conclude that, pending further biochemical enquiry into the enzyme(s) used in the PCR, none of reasons conventionally proposed for the plateau phase of the PCR are sufficient to explain the phenomenon. This being so, we define the plateau as being a feature of the reaction as a whole and, since the onset of this phase is simultaneous for all amplicons, quantitation using the internal control system need not require exponential amplification. This therefore greatly simplifies the quantitative application of PCR.

Animals↗
PubMed1993

TGF-beta s and TGF-beta type II receptor in human epidermis: differential expression in acute and chronic skin wounds.

Exogenously applied transforming growth factor-beta (TGF-beta) isoforms enhance wound healing processes in animal models; however, little is known about the expression of endogenous TGF-beta s and TGF-beta receptors in intact human skin or during wound healing. The present study has revealed several unexpected findings by means of in situ hybridization and immunohistology techniques. In humans, TGF-beta 3 is constitutively expressed in the epidermis of intact skin and in that of acute and chronic wounds--a pattern of expression closely mirrored by the TGF-beta type II receptor. Although not detected in intact skin, TGF-beta 1 mRNA expression was observed in the regenerating epidermis of acute (thermal) wounds but was not found in chronic decubital (pressure) wounds. TGF-beta 2 mRNA expression was not detected in the epidermis of any human skin or wound biopsies. From these findings we suggest that constitutive expression of TGF-beta 3 is important for maintenance of epidermal differentiation and that an induction of TGF-beta 1 expression is essential for re-epithelialization of human skin wounds. Lack of TGF-beta 1 expression in chronic pressure wounds may be associated with their protracted healing tendencies.

Adult↗
PubMed1993

Practices of epilepsy during pregnancy: a survey of Canadian neurologists.

The optimal management of epilepsy in epileptic pregnancies remains controversial. We surveyed all neurologists in Canada to determine their usual practice in managing epilepsy during pregnancy. We identified 436 neurologists in the 1990 edition of the Canadian Handbook of Medical and Surgical Specialists. We mailed a questionnaire enquiring with respect to details of management of epilepsy during pregnancy to all neurologists; in the case of nonrespondents, a follow-up questionnaire was mailed eight weeks later. We achieved a 65% response rate. We found that carbamazepine was the antiepileptic drug of first choice for the management of epilepsy during pregnancy among the majority of neurologists (75%), while phenobarbital (10%) and phenytoin (11%) were recommended much less frequently. Eight percent of respondents never used polytherapy during pregnancy. Despite recent controversy over the reproductive safety of carbamazepine, monotherapy with carbamazepine is regarded by the vast majority of Canadian neurologists as the therapy of first choice for epilepsy during pregnancy.

Anticonvulsants↗
PubMed1993

Diurnal variation in myeloid bodies of the chick retinal pigment epithelium.

Myeloid bodies (MBs) are distinct lamellar regions of the normally branched tubular smooth endoplasmic reticulum of retinal pigment epithelial (RPE) cells. These organelles are present in the retinas of many lower vertebrates. Previous investigations have reported a relationship between outer segment disk shedding and phagocytosis by the RPE, and the formation of MBs. The current morphometric study was undertaken to establish if a temporal relationship existed between MB occurrence and the phagocytosis of shed photoreceptor outer segment tips in the chick retina. We report on the occurrence of phagosomes, MBs, and for the first time, MB precursors (templates) in the RPE over a 24-hr diurnal cycle. Phagosome numbers were observed to be highest within 2 hr following lights on, and again following lights off, while MB precursors were most prevalent at two time points, immediately prior to the times for rod and cone outer segment shedding at lights on and lights off respectively. Traditional MBs of the small (0.06 to 0.239 microns2) and medium (0.24 to 0.99 microns2) variety increased both in size and number from 01:00 hr of a 24 hr time period, with smaller and fewer MBs being present late in the dark part of the diurnal cycle, and larger and more numerous MBs in the later part of the light portion and into the early part of the dark portion of the cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Delivery systems for the care of persons with HIV infection and AIDS.

HIV infection and AIDS are pathologic conditions that more than any other disease require the concerted, cooperative efforts of the health care profession and the community. This article discusses the development of delivery systems for the care of persons with HIV infection and AIDS, highlights what systems have been successful, and indicates the areas in which further research and development are needed. Topics discussed include the costs of care; identifying and meeting the specific health care needs of the HIV-infected population; and long-term, community-based, hospice, and hospital care.

Acquired Immunodeficiency Syndrome↗