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Biomedical subjects

P Mills

Publications and source records attributed to P Mills.

At least 73 records · Page 4Linked to original sources
PubMed1994

Characteristics of families of children who refuse post-divorce visits.

Compared to 88 non-refusers, 12 children who refused post-divorce visits with their noncustodial parents were significantly more likely to be female, to be the oldest child at home, to be in special education, and to have at least one parent with evidence of psychopathology, particularly substance abuse, violence toward spouse, suicidal behavior, or psychosis. Most children in both groups lived primarily with their mothers.

Adolescent↗
PubMed1993

Effects of methylmercury and trimethyltin on cardiac, platelet, and aorta eicosanoid biosynthesis and platelet serotonin release.

The effects of two organometals on heart, platelet, and aorta prostaglandin biosynthesis were examined in vitro. Methylmercuric chloride (MMC, 39-796 nM) increased the biosynthesis of thromboxane A2 (TxA2) and prostacyclin (PGI2) in the heart and stimulated the biosynthesis of PGI2 in incubates of aorta rings. The aorta biosynthesis of PGI2 was monitored by its inhibition of platelet aggregation and serotonin [5-hydroxytryptamine (5-HT)] secretion, while the metabolites 6-keto-PGF1a and TxB2 were quantified by radioimmunoassay. In platelet experiments, low concentrations of MMC (5 microM) enhanced aggregation to adenosine diphosphate (ADP) and at high concentrations MMC (50-100 microM) directly stimulated aggregation and 5-HT secretion. These effects of MMC were inhibited by nonsteroidal antiinflammatory drug, thromboxane synthetase, and phospholipase A2 inhibitors. Trimethyltin (TMT), another highly toxic organometal, had no effect on prostaglandin biosynthesis in either heart or aorta incubates. TMT did not increase platelet aggregation responses to ADP, nor did it directly trigger aggregation. At moderate concentrations, TMT (20-45 microM) slightly depressed ADP aggregation; however, this was paradoxically associated with increased 5-HT secretion. In platelets pretreated with either NDGA or ASA, TMT in the absence of aggregation enhanced 5-HT secretion in response to ADP. TMT, unlike MMC, did not stimulate platelet TxB2 biosynthesis from exogenous [3H]arachidonic acid, whereas MMC stimulates heart, vascular, and platelet eicosanoid biosynthesis. TMT, unlike MMC, does not directly activate the arachidonic acid cascade.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Does reactivity testing in the laboratory reflect blood pressure changes elsewhere?

This study examines whether reactivity testing in a laboratory setting might identify individuals whose blood pressure (BP) fluctuates excessively outside of the laboratory. Eighty-eight normotensive and untreated hypertensive patients were studied. Patients' BPs were obtained repeatedly on two separate screening occasions. They were subsequently admitted to a research ward, and 4 days later their BPs were measured at resting baseline and in response to a series of stressful tasks. Blood pressure declined by 14/11 mm Hg +/- 1.2/1.1 mm Hg (SE) from screening to the in-patient resting baseline. The four stressful tasks all led to increases in BP over the in-patient resting baseline level. Individuals with increased amounts of task-induced reactivity in the laboratory were also more likely to be those whose BP declined the most from out-patient screening to hospitalized baseline. The average correlation between the drop in BP associated with hospitalization and the BP reactivity to each stressor task was r = 0.33 for systolic BP (p < 0.01) and r = 0.24 for diastolic BP (p < 0.05). Reactivity responses in a laboratory setting may convey information about blood pressure fluctuation in the real world.

Adult↗
PubMed1992

Chromogranin A correlates with norepinephrine release rate.

Chromogranin A (CgA) is an acidic protein co-released with catecholamines during exocytosis from sympathetic nerve terminals and chromaffin cells. Previous work has demonstrated that large scale perturbations in sympathetic nervous system (SNS) functioning result in corresponding changes in CgA levels in plasma. Little is known about the physiologic significance of CgA. We hypothesized that, since CgA and catecholamines are co-released from the same storage vesicles, and since CgA is not subject to reuptake or enzymatic metabolism, plasma CgA should reflect norepinephrine release from sympathetic terminals. We therefore measured venous CgA, norepinephrine levels, and norepinephrine release rate in 30 unmedicated subjects. Although the correlation of CgA with plasma norepinephrine was only modest (r = 0.37, p less than 0.05), its correlation with norepinephrine release rate was highly significant (r = 0.58, p less than 0.001). Thus, CgA may offer a novel perspective on peripheral sympathetic activity.

Adult↗
PubMed1992

Young infarct patients with single-vessel occlusion do not have an underlying prothrombotic state to explain their coronary occlusion.

To determine the importance of a prothrombotic state in the pathogenesis of coronary occlusion in young infarct patients, assessment of risk factor profile and thrombotic tendency was undertaken in 25 young male patients (age less than 45 yr) who were shown at angiography, following myocardial infarction, to have occlusion of a single coronary. Comparison was made with a control group of symptomatic males aged greater than 55 yr, who at angiography had significant disease in two or more coronary arteries (multi-vessel disease control group). At the time of the study more patients in the single-vessel disease study group smoked cigarettes (n = 12) compared to the control group (n = 5) (p less than 0.01). Serum cholesterol and triglycerides were higher, and high density lipoprotein-cholesterol lower, in the single-vessel disease group but the difference reached significance only with the high density lipoprotein-cholesterol. Quantitative platelet aggregability was similar in the two groups. Although the level of beta-thromboglobulin, was higher in the single-vessel disease study group the difference was not significant. There were also no significant differences between these groups in levels of fibrinogen, Factor XII and alpha-2 antiplasmin. Patients in the multi-vessel disease group, however, had increased Factor VII levels (p less than 0.01). There were no significant differences between the two groups in fibrinolytic potential or in levels of antithrombin III. Coronary occlusion in the young appears likely to be due primarily to an arterial (plaque) related event as opposed to an abnormal coagulation response to minor arterial plaque damage.

Adult↗
PubMed1992

Influence of pressure supports on joint range of motion.

Burn patients often complain of restricted mobility following application of elasticized nylon anti-burn-scar supports. This study was designed to analyse the influence of this type of pressure garment on joint range of motion (ROM). Data were compiled from 80 burn-affected joints of 17 burn patients placed in a support for the first time. Joint ROM was measured directly prior to, and again immediately following, the donning of the pressure support. ROM was measured using standard goniometric techniques. Range of motion increased in 26 joints (32.5 per cent), decreased in 26 joints (32.5 per cent) and showed no change in 28 joints (35 per cent) after application of the pressure garment. There were no correlations between ROM results and age, time postburn and per cent TBSA in this population. Patients were also asked if movement felt any different after the support was applied. Their varied comments, such as movement felt easier or more difficult, were consistent with the actual ROM data. It appears that there is no predictably detrimental change in joint ROM due to the application of pressure garments.

Adult↗
PubMed1992

Analysis of set screw and side-lock connector reliability.

A retrospective review of complications with connectors and lead-to-header interfaces was performed following 649 pacing procedures between 1980 and 1990. There were 88 lead revisions (13.6%), 81 device replacements or modifications (12.5%), and 480 new implants (74%) using devices of five manufacturers. Two basic connector types were studied, one utilizing a set screw and the other using a side-lock compression fitting. The set screw makes electrical contact and mechanically secures the lead connector pin with a set screw insulated by a self-sealing grommet or an integral or separate set screw cover. The side-lock makes electrical contact with an automatic spring mechanism while the plastic lead terminal is secured in the connector block of the pacemaker by a Delrin side-lock compression fitting. Four hundred fifty-nine set screw connector devices were followed for up to 12 years with 14 complications (3.1%) whereas 82 side-lock connector devices were followed for up to 5 years with one complication (1.2%). The set screw and side-lock connectors were reliable over the period of follow-up. Although the complication rate appeared lower with the side-lock, follow-up was shorter and the number of implants smaller. With the leads used in this study, the side-lock proved to be a desirable feature due to simplicity, speed, safety, and ease of use. One limitation is the requirement for a precise IS-1 connector terminal diameter.

Electrodes, Implanted↗
PubMed1992

Converting enzyme inhibition and blood pressure reactivity to psychological stressors.

There is considerable interest in blood pressure reactivity to psychological stressors. Because the sympathetic nervous system and the renin-angiotensin system are so responsive to stressors and are themselves the targets of many antihypertensive medications, many investigators have wondered if such medications decrease the blood pressure response to stressful stimuli. We studied 25 normotensive and 21 hypertensive men in a double-blind crossover study during which they received either placebo for 4 days or captopril (25 mg b.i.d.) for 4 days while they were hospitalized in a clinical research center. Patients were studied at resting baseline, while performing a mathematics task, and while reading out loud a disturbing newspaper article. Although captopril lowered the resting blood pressure levels, it had no effect on the amplitude of reactivity to stressors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

Psychosocial correlates of reactivity in black and white men.

This study sought to clarify the relationship between cardiovascular reactivity, hostility, depression and ethnicity. Blood pressure and heart rate responses to a standard arithmetic stressor were analyzed in 97 unmedicated hypertensive and normotensive men. Hypertensives and normotensives showed similar increases from baseline on systolic and diastolic blood pressure and on heart rate. Among whites (N = 44), systolic and diastolic reactivity were related to lower scores on the Verbal subscale items of the Buss-Durkee Hostility Inventory (p less than 0.05, for both). Among blacks (N = 53), no such relationship was found. Heart rate reactivity was related to greater depression scores among whites (p less than 0.01), but not among blacks. Among black subjects, heart rate increases were related to higher scores on the Indirect Anger subscale items of the Buss-Durkee (p less than 0.05). These results suggest that the expression of emotion and reactivity to a psychosocial stressor may be socioculturally mediated.

Adolescent↗
PubMed1991

Technical report: percutaneous treatment of a pancreatic duct fistula facilitated by an hydrophilic guide wire.

A case in which a pancreatico-cutaneous fistula was successfully treated percutaneously is presented. The use of an hydrophilic guide wire enabled a catheter to be negotiated across an irregular abscess cavity and into the occluded main pancreatic duct. The low friction and good flexibility of hydrophilic guide wires can greatly facilitate difficult procedures.

Catheterization↗
PubMed1991

Hypertensives' pressor response to norepinephrine. Analysis by infusion rate and plasma levels.

After 5 days of a 10 mEq sodium diet or 4 days of a 200 mEq sodium diet, 15 hypertensives and 11 normotensive control subjects received pressor doses of intravenous norepinephrine (NE). Analysis of pressor responses to the rate of NE infusion showed that the high salt diet sensitized subjects so that they needed less NE to raise systolic blood pressure (SBP) 20 mm Hg (P = .005). There was a complex interaction of salt intake, black race, and hypertension on NE pressor sensitivity (P = .03). Hypertensives attained lower plasma NE levels during the stepwise NE infusion, so we reanalyzed NE sensitivity in terms of the changes in plasma NE levels. This analysis also showed that during the high salt diet, subjects initiated a pressor response at lower plasma NE levels (P = .017) and raised SBP 20 mm Hg at lower NE levels (P = .007). The reanalysis showed that hypertensives initiated a pressor response at lower plasma NE levels (P = .03) and raised SBP 20 mm Hg at lower NE levels (P = .002). Plasma NE levels should provide a better guide to the concentration of NE at cardiovascular receptors than the rate of NE infusion. Analysis of pressor responses to plasma NE levels demonstrated that the hypertensives had an exaggerated pressor response to NE.

Black People↗
PubMed1990

Influence of altered phospholipid composition of the membrane outer layer on red blood cell aggregation: relation to shape changes and glycocalyx structure.

Reversible aggregation of erythrocytes was investigated after alteration of the phospholipid content in the membrane outer leaflet either by disturbance of endogenous transmembrane lipid asymmetry through changes in cellular free calcium, or by incorporation of exogenous lyso-derivatives. It was found that both calcium loading and lyso-phosphatidylcholine (LPC) addition induce a strong increase in red cell-red cell adhesive energy, whereas lyso-phosphatidylserine (LPS), added in the same amount as LPC, does not. Red cell morphological studies show differences in the shape change efficiency of LPS, LPC and calcium loading. However, it was further demonstrated that shape change is not directly responsible for the observed adhesive energy increase, since neuraminidase or trypsin treatment abolish this increase, even though the shape changes induced by alteration of phospholipid organization are not affected. The latter experiment strongly suggests that the red cell adhesive energy increase results from an alteration of the glycocalyx structure, which could be in turn a consequence of the shape change.

Calcium↗