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Biomedical subjects

C Pierce

Publications and source records attributed to C Pierce.

At least 19 recordsLinked to original sources
PubMed1996

The manganese stabilizing protein of photosystem II modifies the in vivo deactivation and photoactivation kinetics of the H2O oxidation complex in Synechocystis sp. PCC6803.

Dark deactivation and photoactivation of H2O-splitting activity were examined in a directed mutant (delta psbO) of Synechocystis sp. PCC6803 lacking the extrinsic manganese-stabilizing protein of the photosystem II (PSII) reaction center complex. Rapid (t1/2 = 10 min) losses of H2O-splitting activity were observed for delta psbO cells kept in the dark, but not for wild-type cells. The loss of H2O-splitting activity by delta psbO cells was suppressed by maintaining the cells under illumination and dark losses were rapidly (t1/2 < 1 min) reversed by light. Photoactivation kinetics of delta psbO and wild-type cells were compared following hydroxylamine extraction of PSII Mn. Photoactivation of delta psbO cells under continuous illumination occurs at an intrinsically faster rate (about 4-fold) than the wild-type. Virtually all of the increase in the rate of photoactivation can be accounted for by a corresponding 4-fold increase in the relative quantum yield of photoactivation as indicated by the yield of photoactivation as a function of flash number. The flash frequency dependence of photoactivation indicates a multi-quantum process in the mutant resembling the wild-type, but with significant increases in yields at all flash frequencies examined. The higher quantum yield of photoactivation in delta psbO cells occurs in the absence of large changes in the kinetics of the rate-limiting dark rearrangement. The results are consistent with increased accessibility (or affinity) and photooxidation of Mn2+ at one or both of the two binding sites involved in the initial stages of the photoactivation mechanism. In the context of previous results, it is proposed that MSP regulates the binding/photooxidation of the second Mn2+ of the photoligation sequence, but not the first.

Bacterial Proteins↗
PubMed1993

A modest proposal.

Explore the source record for details and available documents.

Health Care Costs↗
PubMed1992

Assessment of buccal separators in the relief of bruxist activity associated with myofascial pain-dysfunction.

The purpose of this study was to evaluate the effectiveness of heavy (S2) Alastik separators in relieving bruxist activity as monitored through masseter muscle area EMG activity, muscle palpation, and self-reporting in 21 Caucasian subjects. The subjects, all of whom suffered from both bruxism and myofascial pain-dysfunction, were randomly assigned to one of three groups: experimental (separator group); placebo (separator placed and removed); and control groups (no separator). The findings from this study indicate that there were no observable differences in either subjective or objective responses to the pretreatment versus posttreatment questionnaire and clinical examination for tooth clenching or grinding, facial pain, and fatigue of the jaws. In addition, no statistical differences were found between pre and posttreatment data. The EMG data did not show any statistical differences between pretreatment and posttreatment evaluations or among the 3 groups.

Adult↗
PubMed1992

Profile of a sample of subjects admitted to an acute care psychiatric facility with manic symptoms.

A prospective survey was conducted on 155 consecutive subjects with manic symptoms admitted to an inpatient psychiatric facility to identify possible reasons for rehospitalization. Approximately one third were previously hospitalized at the same facility within the past month. Over half (57%) of the sample were admitted because of aggressive episodes. On admission, 80 percent were receiving carbamazepine or lithium for a mood disorder, and 52.3 percent were receiving multiple medications, of which antipsychotics accounted for over half. Forty-four percent of the sample had comorbid substance use on admission, with marijuana and stimulants accounting for the majority of illicit drug use. Medication noncompliance in 64 percent, and identifiable psychosocial stressors in 55 percent, were also likely contributors to rehospitalization. The data highlights specific treatment issues in the care of patients with a manic component to their illness, and suggests the need for individualized discharge planning with careful followup and continual patient education to assist in the transition from inpatient to society.

Acute Disease↗
PubMed1991

Determinants of one-year outcome from balloon aortic valvuloplasty.

Balloon aortic valvuloplasty (BAV) has been a therapeutic alternative treatment for severe symptomatic aortic stenosis. Previous studies have been unable to predict 1-year outcome because of limited acute and follow-up clinical, invasive and echocardiographic data. The purpose of this study was to predict long-term outcome based on comprehensive data obtained at the time of valvuloplasty and at 3 and 6 months after the procedure. Of 170 consecutive patients undergoing BAV, 108 (mean age 78 years) were at least 1 year from their procedure. Prospective clinical, micromanometer hemodynamic, digital ventriculographic and echocardiographic/Doppler data were collected at baseline and immediately after the procedure. Echocardiographic data were also obtained at 3 and 6 months. With use of Cox model analysis, major events (defined as cardiac death [n = 30], aortic valve replacement [n = 21] or repeat BAV [n = 13]) were predicted by advanced age, baseline heart failure class, and baseline echocardiographic-determined diastolic left ventricular diameter. Only baseline left ventricular ejection fraction proved to be a significant predictor of cardiac death (p = 0.002) in a multivariate model. Absolute values after BAV (stroke work, first derivative of left ventricular pressure, valve area, end-systolic volume, Fick cardiac output, transvalvular gradient) and acute changes measured by catheterization or echocardiography did not provide additional predictive information over that of post procedure ejection fraction. Similarly, echocardiographic valve area and transvalvular gradient at 3 months added no further prognostic data. With an ejection fraction greater than or equal to 45% (n = 63), cardiac survival at 1 year was 80%, irrespective of age, sex, congestive heart failure class or severity of coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Surgical aortic valvuloplasty using the Cavitron Ultrasonic Surgical Aspirator: an invasive hemodynamic follow-up study.

Valve repair and calcium debridement in patients with calcific aortic stenosis, using the Cavitron Ultrasonic Surgical Aspirator (CUSA), results in a reduction in the aortic valve gradient while potentially avoiding long-term problems inherent to prosthetic valves. Invasive followup data in these patients has not previously been reported. Ten patients in whom CUSA debridement was performed underwent cardiac catheterization prior to and 8.0 +/- 2.5 months following the procedure. Compared to baseline, the aortic valve area significantly increased from 0.75 +/- 0.2 to 1.1 +/- 0.3 cm2 (p = 0.009) and the mean gradient was significantly reduced from 54 +/- 21 to 27 +/- 21 mmHg (p = 0.02) at followup. No significant change was noted in cardiac output, ejection fraction, left ventricular end systolic or diastolic volumes or left ventricular end diastolic pressure. However, 6 patients were found to have at least one grade worsening of aortic regurgitation. The development of increased aortic insufficiency in many patients after CUSA aortic valve debridement will likely limit this procedure's clinical utility.

Aged↗
PubMed1991

Standardization of ELISA for the detection of anti-cardiolipin antibodies--effect of non-specific IgG binding.

Various frequencies of anti-cardiolipin antibodies reported in patients with systemic lupus erythematosus and other autoimmune and infectious diseases necessitates the need for standardization of the immunoassay. We report here the usefulness of "no-antigen" control for each serum in determining the actual value of the anti-phospholipid antibodies. This non-specific "no-antigen" binding was quite variable from serum to serum and in general was higher in the patient population than in healthy individuals which served as controls. This non-specific binding may be associated with the increased IgG content of the sera as shown by the linear association of the absorbance of the back-ground readings to increases in IgG concentration (correlation coefficient 0.98).

Antigen-Antibody Reactions↗
PubMed1988

Association of preference for modality to learning of rhythm patterns in music.

This study examined the relationship between preferences for learning modality and the learning and short-term retention of musical rhythm patterns. 55 third graders completed the Swassing Barbe Modality Index. These students were also presented two-measure rhythm patterns through their visual, auditory, and kinesthetic modalities. Analysis indicated that children who preferred on the modality index one modality over others tended to prefer that same modality when learning simple musical rhythms.

Auditory Perception↗
PubMed1983

Effects of verapamil on coronary hemodynamic function and vasomobility relative to its mechanism of antianginal action.

The effect of intravenous verapamil on systemic and coronary hemodynamic function was studied at cardiac catheterization in 12 patients with coronary artery disease. Verapamil was administered as a 2-minute bolus (0.145 mg/kg) followed by an infusion (0.005 mg/kg/min). Cardiac output and coronary sinus blood flow were measured by thermodilution techniques. Caliber of the large coronary arteries and of diseased segments was determined from the coronary angiogram using a computer-assisted method. Verapamil reduced mean arterial pressure 14% (p less than 0.001), systemic vascular resistance 21% (p less than 0.01), and stroke work index 16% (p less than 0.001). Coronary vascular resistance decreased 24% (p less than 0.01) with a small increase in coronary sinus blood flow (+13%, difference not significant [NS]). Myocardial oxygen consumption determined in 5 patients showed no significant change with verapamil. Luminal area in 39 coronary lesions was measured in the "normal" portion of the diseased segment and at its maximal constriction, and an estimate of flow resistance in the stenosis was computed. Overall, 50% of "normal" and of diseased coronary segments dilated significantly with verapamil. Stenosis dilation resulted in an average 14% reduction (p less than 0.01) in estimated flow resistance. In 8 patients, the luminal changes (n = 27) induced by sublingual nitroglycerin were compared with those induced by verapamil. Nitroglycerin induced a significantly greater increase in coronary caliber in both normal and diseased segments; estimated stenosis flow resistance decreased 28% with nitroglycerin compared with 14% with verapamil (p less than 0.01). Thus, verapamil moderately dilates the systemic and coronary small vessel resistance bed without apparently increasing myocardial metabolic demand. Furthermore, verapamil mildly dilates large coronary conductance vessels in both "normal" and diseased segments, although significantly less than does nitroglycerin.

Aged↗
PubMed1981

Rights and responsibilities.

As an alternative to rights theory, John Ladd proposes an ethics of responsibility based on interpersonal relationships. These relationships, described as friendships, are personal in nature, founded on trust, and obtain between doctor and patient, parent and child, etc. Ladd presents his views in a most appealing way -- helping the needy, being friends with the doctor. We argue that Ladd's ethics of responsibility is plausible only because he ignores the facts of power which rights theory was designed to take into account, and that rights and the corresponding institutional model of medicine are indeed appropriate to the physician/patient relationship.

Ethics↗
PubMedDate not supplied

Suppressed anger and blood pressure: the effects of race, sex, social class, obesity, and age.

We studied 572 men and women who participated in a blood pressure screening program at a government unemployment office. Before having their blood pressures taken, the subjects completed a brief questionnaire that included two items measuring conflict over anger expression. Information was also obtained on obesity, race, sex, social class, and age. Across all subjects, systolic blood pressure was found to be significantly related to suppressed anger (p less than 0.016). Normotensive were twice as likely as hypertensives to be free of suppressed anger. This relationship remained after controlling for the covariates of age, social class, and obesity. The relationship between suppressed anger and systolic blood pressure was significant for white men, exhibited a trend in black men, and was not significant for women. In contrast to the systolic findings, suppressed anger was unrelated to diastolic pressure in all the analyses.

Adult↗
PubMedDate not supplied

Anti-phospholipid antibody profiles of different specificities in syphilis and systemic lupus erythematosus.

Controversies exist as to the differences in the specificities of phospholipid antibodies in SLE and syphilis. We report an ELISA assay that could distinguish phospholipid antibodies associated with SLE and syphilis based on their differential reactions with phosphatidyl choline and VDRL antigens. Antibodies to phospholipid from patients with SLE reacted equally well when tested with these two antigens in the ELISA assay whereas phospholipid antibodies present in syphilis patients exhibited little or no binding to phosphatidyl choline. There were no differences in the binding of phospholipid antibodies to other phospholipids such as cardiolipin and phosphatidyl serine. In addition, there was no association of anti-phospholipid antibodies with the presence of either DNA or RPR antibodies suggesting their distinctness from each other.

Antibodies, Antinuclear↗
PubMedDate not supplied

Reference period analysis of vaginal bleeding with triphasic oral contraceptive agents containing norethindrone or levonorgestrel: a comparison study.

The World Health Organization recommends the use of fixed reference periods for quantification of the incidence and severity of vaginal bleeding when patients use various forms of contraception. Ninety- and 110-day reference periods were used in the analysis of data from daily menstrual diaries kept by 72 healthy women in a one-year study of oral contraceptive agents containing ethinyl estradiol and either norethindrone or levonorgestrel. Analysis of bleeding patterns reported during both 90-day and 110-day periods revealed fewer days of bleeding and/or spotting overall with norethindrone than with levonorgestrel (e.g., a mean of 16.06 vs. 19.55 days, respectively, over the first 90-day period; P = .013) and significantly shorter bleeding and/or spotting episodes with the norethindrone preparation. This trend persisted when data were adjusted for a day-1 pill start. Using either method of analysis, duration of bleeding episodes was shorter among subjects taking norethindrone than levonorgestrel. Pills were missed in both study groups, but more women in the LNG/EE group missed from 1 to 3 pills in at least one cycle (31 vs. 21 in the NET/EE group). The between-group difference in bleeding events may be due to intrinsic hormonal differences in regimens or to the greater number of pills missed among levonorgestrel users.

Adult↗