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Biomedical subjects

C Davis

Publications and source records attributed to C Davis.

At least 163 records · Page 9Linked to original sources
PubMed1997

A new fibre optic sensor for respiratory monitoring.

A new fibre optic plethysmograph has been designed to monitor respiration non invasively. The device incorporates the idea of using thoracic and abdominal belts similar to conventional inductance plethysmography but uses an optical fibre woven into the belts rather than the usual coiled wire. The fibre optic belts incorporate a loop design in the fibre and rely on "macrobending" losses from laser light transmitted down the fibre when the bend radius of the loop changes during respiration. Changes in lung volume are monitored by analysing the relatively large resultant changes in light transmitted through the fibre. The output from the light detector has been interfaced to a computer containing a data acquisition card and the resultant intensity trace is monitored in real time using a virtual instrument created using LabVIEW graphical programming. Preliminary results suggest a highly sensitive system capable of detecting small changes in lung volume using a technique which is not susceptible to electrical noise and which is electrically safe.

Adult↗
PubMed1996

The problem of thrombocytopenia after hematopoietic stem cell transplantation.

Thrombocytopenia after hematopoietic stem cell transplantation (HSCT) is associated with an increased risk of bleeding and utilization of significant resources. This review presents an analysis of risk factors associated with delayed platelet engraftment. The retrospective analysis included 1,468 recipients of autologous or allogeneic transplants treated between January 1, 1990 and July 1, 1995. Risk factors associated with delayed platelet engraftment after autologous HSCT included use of marrow rather than peripheral blood as the source of stem cells, being transplanted for acute myeloid leukemia rather than other diseases, positive patient serology for cytomegalovirus and the presence of infection post-transplant before engraftment. Risk factors associated with delayed platelet engraftment after allogeneic marrow transplantation included unrelated as opposed to related donor transplants, being transplanted for diseases other than chronic myelogenous leukemia, increased age, onset of acute graft-versus-host disease (AGVHD), male gender, the administration of methotrexate for GVHD prophylaxis and the presence of infection before engraftment. Delayed platelet recovery is associated with decreased survival after both autologous and allogeneic transplants. Management of delayed platelet recovery by transfusion of blood products requires significant medical resources and is of some risk to the patients. Further development of new strategies may safely reduce the need for blood products. These include peripheral blood stem cell transplants (allogeneic and autologous), new algorithms for administering routine platelet transfusions and investigative biological agents for stimulating megakaryocytopoiesis. Further studies may elucidate the cause of increased platelet consumption associated with infection and GVHD.

Adolescent↗
PubMed1996

Individual difference variables that predict response to training in phonological awareness.

The cognitive abilities that predicted growth in response to a 12-week training program in phonological awareness were investigated with a sample of 100 kindergarten children. The children were selected from two elementary schools with historically low achievement in reading. Sixty children received training in both analytic and synthetic awareness skills, and 40 children constituted a no-treatment control group. Pretest measures included assessment of phonological awareness, phonological memory and naming rate, letter knowledge, reading and spelling, and general verbal ability. Growth in phonological awareness was assessed during the middle and at the end of the training period. Hierarchical linear modeling was used to estimate individual growth curves in phonological awareness for children in both the treatment and control groups. Initial comparisons between children in the two groups indicated substantial overall training effects in phonological awareness for children in the treatment group. For children in the training group, the model that best predicted growth in analytic awareness included invented spelling and general verbal ability, while growth in synthetic awareness was predicted best by a combination of invented spelling and rapid automatic naming of digits.

Awareness↗
PubMed1996

The effects of moclobemide on sexual desire and function in healthy volunteers.

Decreased sexual desire is a recognized symptom of major depression (MD). Disturbances in sexual function, although reported in drug = free patients, have more often been viewed as adverse drug effects during antidepressant treatment with established classes of antidepressants (TCA, MAOI, SSRI). However, it is difficult to draw conclusions about the effects of antidepressants on sexual desire and function for two reasons: lack of standardised assessments for sexual function; inability to distinguish depression-related symptoms from drug-induced sexual disturbances. The purpose of this study was to examine the effects of moclobemide (a RIMA antidepressant) on sexual function in healthy male and female volunteers. Sixty male and female volunteers were randomly assigned to either moclobemide 300 mg or placebo for 3 weeks. They were seen at weekly intervals to assess drug compliance and to complete a 10-item sexual function questionnaire (SFQ). In both men and women there were no differences between moclobemide and placebo on measures of sexual desire and function. However, men and women differed in the levels of reported interest and sexual performance.

Adult↗
PubMed1996

Child abuse in Hong Kong revisited after 15 years: characteristics of victims and abusers.

The purpose of this paper was to examine the characteristics of the victims and abusers of child abuse cases on the Child Protection Registry in Hong Kong as of March 1995 and to compare findings with a similar community report of child abuse in Hong Kong conducted approximately 15 years earlier. As of March 31, 1995, there were 457 active cases of child abuse or suspected child abuse (44% male and 56% female) on the computerized Child Protection Registry. Fifty percent of the victims were grade school age children between 7-12, and 62.4% suffered physical abuse. The abusers or suspected abusers were 52% male and 48% female with nearly half (49%) in their thirties. The majority of abusers were married/cohabiting (75%) with only a grade school education (60%). As compared to 1979, there was an increase of sexual child abuse cases, female victims of child abuse, and an increase in male abusers or suspected abusers.

Adult↗
PubMed1996

Bone density in survivors of childhood malignancies.

PURPOSE: The purpose of this study was to assess bone mineralization in survivors of childhood malignancies. PATIENTS AND METHODS: Bone mineral density (BMD) of the lumbar spine was measured in 60 patients aged 5.5-20.1 years (mean, 12.4 years) who had no known disease 1.0-14.5 years (mean, 4.3 years) after completing treatment for a malignancy. The age-normalized BMD findings (Z scores) were correlated with multiple variables, including measures of growth and nutrition, type of malignancy, and various treatments, including use of steroids, methotrexate, or cranial irradiation. RESULTS: BMD was normal in most patients with a mean Z score of -0.28 + 0.14 (+/- SE). Only 8% of the patients were more than 2 SDs below age-matched normal BMD. Weight Z score was the major determinant of BMD Z score. Calcium intake and height Z score were also important variables. CONCLUSIONS: Most survivors of childhood malignancies will not be left with a clinically significant deficit in BMD. Risk factors for diminished BMD include low-weight and low-height Z scores and low calcium intake. Therapeutic interventions are available to address these risk factors in those patients with significantly diminished BMD.

Adolescent↗
PubMed1996

Ethnicity and aged care assessment teams in Queensland.

To examine how functional, medical and psychosocial factors influence the differences in use of community and residential services by Australian-born and ethnic aged persons, all persons (n = 31,737) assessed by aged care assessment teams in Queensland in 1992 and 1993 were surveyed. Subjects were classified as Australian-born, overseas-born in countries where English is the primary language, or overseas-born in countries where English is not the primary language. Factors compared included use of services and residential care both prior to assessment and following assessment, and functional, medical and psychosocial factors. The group with non-English-speaking background were more likely to be both younger and underreferred compared to their proportion in the community. They were more likely to be referred for, and more likely to be recommended for, nursing home placement than the English-speaking groups. They were more commonly referred for assessment because of mental deficit problems, carer stress and/or social isolation, more likely to be diagnosed with dementia and diabetes, and less likely to be diagnosed with respiratory disease and vision disorders. That clients of non-English-speaking background are more likely to be recommended for nursing home placement is probably largely because of more advanced disease at the time of referral and therefore more functional dependence. Aged care assessment teams should increase ethnic communities' awareness of their services, particularly of the benefits of earlier referral.

Activities of Daily Living↗
PubMed1996

Distribution of thiols in microorganisms: mycothiol is a major thiol in most actinomycetes.

Mycothiol [2-(N-acetylcysteinyl)amido-2-deoxy-alpha-D-glucopyranosyl- (1-->1)-myo-inositol] (MSH) has recently been identified as a major thiol in a number of actinomycetes (S. Sakuda, Z.-Y. Zhou, and Y. Yamada, Biosci. Biotech. Biochem. 58:1347-1348, 1994; H. S. C. Spies and D. J. Steenkamp, Eur. J. Biochem. 224:203-213, 1994; and G. L. Newton, C. A. Bewley, T. J. Dwyer, R. Horn, Y. Aharonowitz, G. Cohen, J. Davies, D. J. Faulkner, and R. C. Fahey, Eur. J. Biochem. 230:821-825, 1995). Since this novel thiol is more resistant than glutathione to heavy-metal ion-catalyzed oxidation, it seems likely to be the antioxidant thiol used by aerobic gram-positive bacteria that do not produce glutathione (GSH). In the present study we sought to define the spectrum of organisms that produce MSH. GSH was absent in all actinomycetes and some of the other gram-positive bacteria studied. Surprisingly, the streptococci and enterococci contained GSH, and some strains appeared to synthesize it rather than import it from the growth medium. MSH was found at significant levels in most actinomycetes examined. Among the actinobacteria four Micrococcus species produced MSH, but MSH was not found in representatives of the Arthrobacter, Agromyces, or Actinomyces genera. Of the nocardioforms examined, Nocardia, Rhodococcus, and Mycobacteria spp. all produced MSH. In addition to the established production of MSH by streptomycetes, we found that Micromonospora, Actinomadura, and Nocardiopsis spp. also synthesized MSH. Mycothiol production was not detected in Propionibacterium acnes or in representative species of the Listeria, Staphylococcus, Streptococcus, Enterococcus, Bacillus, and Clostridium genera. Examination of representatives of the cyanobacteria, purple bacteria, and spirochetes also gave negative results, as did tests of rat liver, bonito, Candida albicans, Neurospora crassa, and spinach leaves. The results, which indicate that MSH production is restricted to the actinomycetes, could have significant implications for the detection and treatment of infections with actinomycetes, especially those caused by mycobacteria.

Actinomycetales↗
PubMed1996

Project Solo: an independent practitioner initiative for confidential self-assessment of quality.

Project Solo, a grassroots organization of independent physicians, has developed a unique method of confidential self-assessment of quality. Participating physicians can use the data to improve their own practices and to have a strong, credible voice for retaining and promoting the strengths of independent practices in providing medical care. In a pilot project, 56 independent physicians in Project Solo were given bar-coded, postage-paid survey forms of patient satisfaction to distribute to 100 patients. The population for this pilot study was the 35 physicians with patients returning at least one survey. A total of 1858 surveys (53% of surveys given to physicians) were returned, representing a variety of rural and urban practices in 19 states. The mean percentage of responses rated "excellent" to survey items from Project Solo physicians is similar to the percentages reported for this survey in other studies. We conclude that Project Solo serves as an effective and efficient model for gathering patient satisfaction data and can be further developed as a tool for gathering clinical outcome and other quality measurement data in the solo and small group practice setting.

Demography↗
PubMed1996

The Problem of Thrombocytopenia after Hematopoietic Stem Cell Transplantation.

Thrombocytopenia after hematopoietic stem cell transplantation (HSCT) is associated with an increased risk of bleeding and utilization of significant resources. This review presents an analysis of risk factors associated with delayed platelet engraftment. The retrospective analysis included 1,468 recipients of autologous or allogeneic transplants treated between January 1, 1990 and July 1, 1995. Risk factors associated with delayed platelet engraftment after autologous HSCT included use of marrow rather than peripheral blood as the source of stem cells, being transplanted for acute myeloid leukemia rather than other diseases, positive patient serology for cytomegalovirus and the presence of infection post-transplant before engraftment. Risk factors associated with delayed platelet engraftment after allogeneic marrow transplantation included unrelated as opposed to related donor transplants, being transplanted for diseases other than chronic myelogenous leukemia, increased age, onset of acute graft-versus-host disease (GVHD), male gender, the administration of methotrexate for GVHD prophylaxis and the presence of infection before engraftment. Delayed platelet recovery is associated with decreased survival after both autologous and allogeneic transplants. Management of delayed platelet recovery by transfusion of blood products requires significant medical resources and is of some risk to the patients. Further development of new strategies may safely reduce the need for blood products. These include peripheral blood stem cell transplants (allogeneic and autologous), new algorithms for administering routine platelet transfusions and investigative biological agents for stimulating megakaryocytopoiesis. Further studies may elucidate the cause of increased platelet consumption associated with infection and GVHD.

Journal Article↗
PubMed1996

Chimeric synthetic peptides as antigens for detection of antibodies to HIV-1 and HIV-2.

Two chimeric peptides incorporating immunodominant sequences from both HIV-1 (LGIWGCSGKLICTT) and HIV-2 (LNSWGCAFRQVCHT) were synthesized. Peptides KS1-KS2 and KS2-KS1 represented sequences from the two viruses in both possible orders, separated by two glycine residues as spacers. These peptides were evaluated as antigens in an ELISA using a panel of specimens derived from HIV-1 (n = 25) and HIV-2 (n = 25) infected individuals and seronegative people (n = 38). The results were compared to plates coated with individual peptides KS1 and KS2 and to plates coated with two peptides (KS1 and KS2) together. Data demonstrated that individually, KS1 and KS2, are good antigens and can detect antibodies to their respective viruses quite efficiently. However, when coated together, their ability to detect antibodies to both HIV-1 and HIV-2 was reduced, as evidenced by a decrease in OD values obtained. The chimeric peptides KS1-KS2 and KS2-KS1 detected antibodies to HIV-1 and HIV-2; however, their sensitivity of detection was variable and dependent upon the order of their sequence. For both peptides, antibodies directed to the C-terminal portion were detected with higher sensitivity than those directed to the N-terminal part of the peptides. This may be related to peptide adsorption to the solid surface and epitope accessibility to the antibodies. Such chimeric antigens may be very useful for simultaneous detection of antibodies to HIV-1 and HIV-2.

AIDS Serodiagnosis↗
PubMed1996

Interindividual and interspecies variation in hepatic microsomal epoxide hydrolase activity: studies with cis-stilbene oxide, carbamazepine 10, 11-epoxide and naphthalene.

Microsomal epoxide hydrolase (HYL1) is a single-gene enzyme responsible for the hydrolysis of epoxides derived from the oxidative metabolism of xenobiotics. Variation in HYL1, therefore, may be an important determinant of drug toxicity. We have investigated HYL1 enzyme kinetics in six different species including man, for which a liver bank genotyped for polymorphisms in exons 3 and 4 of the HYL1 gene was used. Activity was measured by radiochromatography with high specific activity radiolabeled substrates, cis-stilbene oxide (CSO) and carbamazepine 10,11-epoxide (CBZ-E). In addition, naphthalene was used to investigate the hydrolysis of an epoxide (naphthalene 1,2-epoxide [N-E] generated in situ. There was marked species variation in enzyme activity that was substrate dependent. CSO was rapidly hydrolyzed by microsomes from all species, the rank order of specific activity being human > rabbit > dog > rat > hamster > mouse. In contrast, hydrolysis of CBZ-E was only observed with human liver microsomes. CBZ-E was only a weak (IC50 = 1 mM) inhibitor of CSO hydrolysis. The hydrolysis of N-E, determined as the diol-to-total metabolite ratio, was human > rabbit > dog > hamster > mouse > rat. Intraspecies variation in man was 4-fold, 7-fold and 2-fold for CSO, CBZ-E and N-E, respectively: none of this variation could be directly accounted for by the HYL1 polymorphisms in exons 3 and 4. These data emphasize the need for careful toxicokinetic evaluation of species used in the safety evaluation of compounds likely to form epoxide intermediates in vivo.

Adult↗
PubMed1996

Clinical trials: testing of adult chemical heating pad.

Chemical packs are recent innovations in the delivery of dry heat. Because these delivery systems do not have any mechanism for verifying temperature during application, research to determine their safety seems warranted. The purpose of this study was to measure the skin temperature of adults during a 30-minute application of the MediHeat adult heating pad (MH-AHP). Seventy-seven subjects received a 30-minute application of the MH-AHP to their backs while lying in both supine and prone positions. The mean skin temperature in both positions was 101 degrees F. There were significant differences, however, in minimum and maximum skin temperature between positions. Subjects in the prone position had significantly higher maximum skin temperature and significantly lower minimum skin temperature than subjects in the supine position. It is possible that the prone position allows for more air flow over the MH-AHP and that more heat was generated causing the higher maximum temperature. This explanation does not account for the lower minimum temperature. There were no significant differences in perception of heat between the positions at either 5 minutes or 30 minutes. Findings suggest that caution is necessary when applying heating devices that depend on air circulation for heat generation.

Adult↗