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Biomedical subjects

M McNulty

Publications and source records attributed to M McNulty.

14 recordsLinked to original sources
PubMed2006

Collagen type-I degradation is related to arterial stiffness in hypertensive and normotensive subjects.

Although arterial stiffness is an independent cardiovascular risk factor associated with both aging and hypertension, relatively little is known regarding the structural changes in the vessel wall that occur with vessel stiffening. We determined if collagen type-I metabolism is related to arterial stiffening in both hypertensive and normotensive subjects. Arterial stiffness was assessed by aortic pulse wave velocity (PWV) and augmentation index (AIx) in 46 subjects (48.7 +/- 2 years, 32 hypertensives) and related to circulating markers of collagen type-I turnover. Collagen synthesis was assessed by the measurement of carboxy-terminal peptide of procollagen type-I (PIP) and collagen degradation by the measurement of carboxy-terminal telopeptide of collagen type-I (ICTP), by quantitative immunoassay. Matrix metalloproteinase-1 (MMP-1) and the tissue inhibitor of metalloproteinase-1 (TIMP-1) were also quantified by immunoassay. The ratio of collagen type-I synthesis to degradation was negatively correlated with both PWV (P<0.05) and AIx (P<0.05), whereas plasma MMP-1 levels displayed a positive correlation with both PWV (P<0.01) and AIx (P<0.01), after adjustment for age and mean arterial pressure. The relationship between collagen type-I turnover and arterial stiffness was similar in both the normotensive and hypertensive subjects. Although circulating markers of collagen synthesis were increased in the hypertensive subjects, this was not related to arterial stiffness. Collagen type-I degradation is increased in relation to collagen type-I synthesis in subjects with stiffer arteries. Matrix metalloproteinase-1, the enzyme responsible for collagen type-I degradation, is positively related to both large elastic and muscular artery stiffness in normotensive and hypertensive subjects.

Adult↗
PubMed2001

Evidence that a copper-metallothionein complex is responsible for fluorescence in acid-secreting cells of the Drosophila stomach.

Copper cells were originally identified in Drosophila midgut epithelium by their striking orange fluorescence in copper-fed larvae. Here, we examined copper cell fluorescence in light of the previous observations that (1) a similar fluorescent signal in yeast is produced by a complex between copper and metallothionein, and (2) metallothionein is expressed constitutively in the copper cell region and inducibly in other regions of the Drosophila midgut. Pulse-feeding experiments with 1 mM CuCl2 revealed that fluorescence appeared rapidly in copper cells (<5 min) and slowly in other cells of the midgut (days), suggesting a constitutive cofactor in the former and an inducible cofactor in the latter. Fluorescence was also detected in Drosophila S2 tissue culture cells after induction of metallothionein synthesis by addition of CuCl2 to the growth medium. Thus, fluorescence coincided spatially and temporally with the expression of metallothionein. Fluorescence was also linked to the acid-secreting activity of copper cells. Fluorescence was not observed when acid secretion was inhibited by a mutation in the alpha spectrin gene and acidification was blocked in copper-fed wild-type larvae. However, acidification was restored after a 1-day chase period in which the fluorescent signal became sequestered within a vesicular compartment. We therefore conclude that copper cell fluorescence is most probably attributable to a cytoplasmic copper-metallothionein complex, suggesting an unanticipated role for metallothionein in acid-secreting cells.

Animals↗
PubMed2000

Effect of tourniquet pressure and intra-individual variability on plasma fibrinogen, platelet P-selectin and monocyte tissue factor.

Small differences in levels of certain haemostatic components may be clinically significant. It is important therefore to eliminate potential sources of confounding variability. This study investigated the effect of removing tourniquet pressure prior to sample collection on plasma fibrinogen levels, platelet P-selectin and monocyte tissue factor expression. Blood was collected from the right arm under maintained tourniquet pressure and from the left arm following the release of pressure once the vein was sufficiently inflated for insertion of a needle. Whole blood was labelled within one hour of venepuncture to allow analysis of platelet P-selectin and monocyte tissue factor by flow cytometry. Plasma fibrinogen levels were analysed in samples stored at -70 degrees C, for all individuals at the end of the study using a method based on the Clauss technique. Intra-individual variability for each of the components was assessed by collecting samples under tourniquet pressure from four individuals on the same day on three consecutive weeks. Intra-individual variations were greater than assay CVs for all three components. There were no significant differences between the two tourniquet methods of collection for fibrinogen, P-selectin or tissue factor. In conclusion, there is no reason not to use a tourniquet during collection of blood for analysis of plasma fibrinogen, platelet P-selectin or monocyte tissue factor.

Adolescent↗
PubMed1999

Access to medical care for adolescents: results from the 1997 Commonwealth Fund Survey of the Health of Adolescent Girls.

PURPOSE: This study examined the factors associated with access to care among adolescents, including gender, insurance coverage, and having a regular source of health care. METHODS: Analyses were done on the 1997 Commonwealth Fund Survey of the Health of Adolescent Girls, a nationally representative sample of in-school adolescents in 5th through 12th grade. Access to health care, missing needed care, and whether the adolescent had private time with their provider were assessed. Cochran-Mantel-Haenszel chi-square statistics were computed using SUDAAN. RESULTS: Nearly a third of the 6748 adolescents surveyed had missed needed care. The most common reason for missing care was not wanting a parent to know (35%). Girls were more likely than boys to miss care (29% vs. 24%). Most adolescents reported using a source of primary health care (92%); girls were more likely than boys to use a physician's office rather than another site (65% vs. 60%). Eleven percent of adolescents reported having no health insurance. Uninsured adolescents were more likely to have missed needed care (46% vs. 25%) [corrected]. CONCLUSIONS: Certain groups of adolescents have less access to health care. Girls have more emotional barriers, such as not wanting parents to know about care, and embarrassment. Adolescents without health insurance are at high risk for missing care because of financial strain. States, insurers, and advocates can influence policies around confidentiality and insurance coverage to address these issues.

Adolescent↗
PubMed1998

Adolescents' access to care: teenagers' self-reported use of services and perceived access to confidential care.

BACKGROUND: Most surveys on adolescents' use of health services rely on parental report, and this may underestimate adolescents' use of confidential services. OBJECTIVE: To investigate adolescents' report of their own use of health services, access to care, and knowledge and use of confidential services. METHOD: A random digit-dialed survey of 14- to 19-year-old adolescents was conducted in Monroe County, New York. We screened 11 800 numbers and identified 4449 households (40%) of which 393 families (8.8%) had eligible adolescents. Of these, 259 (66%) consented and completed an interviewer-administered survey. RESULTS: Almost all adolescents (92%) rated their health as excellent or good and 90% had visited a health care provider within the year. Most (88%) identified a source of primary care. As many as 27% of adolescents had used more than one source of care. Many youth identify school personnel as important resources for health and counseling needs. Only 8.4% of respondents have used services confidentially, but nearly half of all youth did not know where they could obtain confidential care if they needed to. Adolescents were least likely to know where to obtain mental health or substance abuse and reproductive services. CONCLUSIONS: While most youth have used primary care, a substantial minority have not. Many teenagers depend on multiple sources of care, and they rely on school personnel as important sources of health information. Many do not know where they could go to review confidential services or for other services that they may need. Managed care insurance and public health policies should recognize adolescents' access needs to meet them appropriately.

Adolescent↗
PubMed1990

Dopaminergic involvement in the cocaine-induced up-regulation of benzodiazepine receptors in the rat caudate nucleus.

One group of 12 rats received discrete 6-hydroxydopamine (6-OHDA) injections into the caudate nucleus on one side of the brain and sham infusions on the other. Following chronic daily injections of cocaine (20 mg/kg, i.p.) or saline (1 ml/kg, i.p.) for 15 days, the caudate nuclei were separately dissected, and the number of benzodiazepine receptors labeled with [3H]Ro 15-1788 were assessed using individual homogenate receptor binding assays. A second group of 24 rats received bilateral infusions of 6-hydroxydopamine or sham infusions into the lateral ventricles followed by chronic cocaine or saline administration as described above. The animals were sacrificed by cardiac perfusion, and the brains were sectioned and prepared for light microscopic quantitative autoradiography. The extent of the lesion was assessed by measuring dopaminergic and noradrenergic uptake sites visualized with [3H]mazindol, while [3H]Ro 15-1788 was used to estimate the number of benzodiazepine receptors. Chronic cocaine administration resulted in significant increases in benzodiazepine receptors in the caudate nucleus, and these effects were attenuated following dopamine depletion. These data suggest that the effects of cocaine on benzodiazepine receptors may be mediated, in part, through the effects of the drug on dopaminergic neuronal activity.

Animals↗
PubMed1975

A comparison of methods of evaluating myocardial contractility.

An investigation was carried out in dogs to determine how the acceleration of blood in the aorta (dV/dt), as a new index of myocardial contractility compared with existing indices and how they correlated with each other. It was found that the indices derived from velocity and flow of blood, dV/dt max and dQ/dt max, and from intraventricular pressure, dP/dt max, correlate well with each other but there is less agreement between them and the reciprocal of the Pre-Ejection Period, l/PEP. The ratio dP/dt max divided by I.P. correlated well with dQ/dt max divided by I.Q. and dQ/dt max divided by Q. max but not so well with dV/dt max divided by I.V. (instantaneous velocity) of dV/dt max divided by V. max and the ratios dQ/DT DIVIDED BY I.Q. and dQ/dt divided by Q max as well as l/PEP. In view of the lack of agreement of quantitative definition of myocardial contractility, the ratio dV/dt divided by V. max would have several practical advantages as an indicator of the inotropic state of the heart; these are that the probe used to establish descending aortic blood velocity does not require calibration, and the signal can be obtained by a relatively non-invasive technique that is suitable for patient care and yet agrees with other established indices of myocardial contractility.

Animals↗