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Biomedical subjects

L Shaw

Publications and source records attributed to L Shaw.

At least 91 records · Page 5Linked to original sources
PubMed1997

Continuous monitoring of salivary flow rate and pH at the surface of the dentition following consumption of acidic beverages.

Use of a splint-mounted flexible pH electrode has allowed reliable continuous monitoring of pH at the surface of the dentition whilst still enabling subjects to drink normally. pH was monitored at the palatal upper left central incisor and upper right first permanent molar sites after drinking 1% (w/v) citric acid. A maximal decrease in pH to values of 2-3 was observed after 1 min followed by a slower recovery which was above pH 5.5 within 2 min at the former site and in 4-5 min at the latter site. A sharp rise in parotid saliva flow rate was seen at 1 min after drinking the same concentration of citric acid by glass, straw or feeder cup, which returned to resting levels within 6 min although the fall-off of flow rate was slower with the feeder cup. Thus, after dietary acid intake the pH at the surface of the dentition is below the critical pH for enamel dissolution for shorter periods than previously suggested, which is probably a reflection of salivary neutralisation and washing.

Adolescent↗
PubMed1997

Genetic and environmental contributions to healthcare need and utilization: a twin analysis.

OBJECTIVE: An exploratory study to examine the genetic and environmental influences on healthcare-seeking behavior for four health conditions (high blood pressure, mental health problems, joint disorders, and hearing problems). DATA SOURCES: Data collected from 3,602 male-male twin pair members of the Vietnam Era Twin (VET) Registry. STUDY DESIGN: Varying models for the relationship between genetic and environmental influences on health condition liability and on treatment use were tested in an attempt to explain the relative contributions of additive genetic, common, and unique environmental effects to health condition and treatment use. DATA COLLECTION: A mail and telephone survey of general health status was administered in 1987 to VET Registry twins. PRINCIPAL FINDINGS: Variance component estimates under the best-fitting model for the genetic component ranged from 24 percent to 52 percent for the condition status and from 42 percent to 56 percent for treatment-seeking behavior. CONCLUSIONS: Utilization models that consider only environmental parameters will leave a large percentage of variability unexplained. Familial patterns have an impact not only on disease susceptibility but also on healthcare utilization, thereby having lifelong implications for social and fiscal constraints placed on the healthcare system. Thus, explanatory models for healthcare utilization behavior should consider the contribution of genetic factors in the decision to seek and use health services.

Adult↗
PubMed1997

Multicenter study of Abbott AxSYM Digoxin II assay and comparison with 6 methods for susceptibility to digoxin-like immunoreactive factors.

Performance characteristics of the Abbott nonpretreatment AxSYM Digoxin II assay were evaluated for quantification of digoxin at four independent sites. Correlation of digoxin measurements with the Abbott pretreatment AxSYM, Baxter Stratus II, Abbott TDx/ TDxFLx II, Abbott IMx, Emit 2000, and Beckman Synchron CX digoxin assays showed acceptable agreement, as indicated by: slope values > 0.84, r > 0.90, y-intercepts for all comparisons at or below the assay detection limit, and Sy/x ranging between 7.5% and 15.4% of the average digoxin value. Susceptibility to interference from digoxin-like immunoreactive factors (DLIFs) was examined in 233 samples from renal patients, liver disease patients, cord blood, and third-trimester pregnancies; the AxSYM Digoxin II assay demonstrated the least DLIFs interference. DLIF susceptibility for four of the methods was significantly greater (P < 0.05) than in the AxSYM Digoxin II assay; susceptibilities of the Stratus II and Emit 2000 methods were similar to the AxSYM Digoxin II assay.

Autoanalysis↗
PubMed1997

The epidemiology of tooth wear.

There is a perception within the dental profession that the problem of pathological loss of tooth tissue is increasing. However, methods used to measure tooth wear are often complex and not reproducible. This fact, together with the lack of information on 'normal' loss of tooth tissue suggests that conclusions from current prevalence studies should be treated with caution.

Adolescent↗
PubMed1996

Tooth wear--dental erosion.

This article aims to address the issues arising out of the increasing concern by general dental practitioners of erosion-related tooth wear. The prevalence, common presentation, differential diagnosis, likely aetiology, prevention and management of suspected cases of this form of tooth wear are considered.

Adolescent↗
PubMed1996

CMP-N-acetylneuraminic acid hydroxylase: the first cytosolic Rieske iron-sulphur protein to be described in Eukarya.

Electron paramagnetic resonance (EPR) spectroscopy and analysis of the primary structure of the CMP-N-acetylneuraminic acid hydroxylase revealed that this enzyme is the first iron-sulphur protein of the Rieske type to be found in the cytosol of Eukarya. The dithionite-reduced hydroxylase exhibited an EPR signal known to be characteristic for a Rieske iron-sulphur centre (2Fe-2S), the g-values being 1.78, 1.91 and 2.01, respectively. An analysis of the primary structure of the hydroxylase led to the identification of an amino acid sequence, known to be characteristic for Rieske proteins. Furthermore, possible binding sites for cytochrome b5, the substrate CMP-Neu5Ac and a mononuclear iron centre were also identified.

Amino Acid Sequence↗
PubMed1996

Transmissible gastroenteritis coronavirus, but not the related porcine respiratory coronavirus, has a sialic acid (N-glycolylneuraminic acid) binding activity.

The hemagglutinating activity of transmissible gastroenteritis virus (TGEV), an enteric porcine coronavirus, was analyzed and found to be dependent on the presence of alpha-2,3-linked sialic acid on the erythrocyte surface. N-Glycolylneuraminic acid was recognized more efficiently by TGEV than was N-acetylneuraminic acid. For an efficient hemagglutination reaction the virions had to be treated with sialidase. This result suggests that the sialic acid binding site is blocked by virus-associated competitive inhibitors. Porcine respiratory coronavirus (PRCV), which is serologically related to TGEV but not enteropathogenic, was found to be unable to agglutinate erythrocytes. Incubation with sialidase did not induce a hemagglutinating activity of PRCV, indicating that the lack of this activity is an intrinsic property of the virus and not due to the presence of competitive inhibitors. Only monoclonal antibodies to an antigenic site that is absent from the S protein of PRCV were able to prevent TGEV from agglutinating erythrocytes. The epitope recognized by these antibodies is located within a stretch of 224 amino acids that is missing in the S protein of PRCV. Our results indicate that the sialic acid binding activity is also located in that portion of the S protein. The presence of a hemagglutinating activity in TGEV and its absence in PRCV open the possibility that the sialic acid binding activity contributes to the enterotropism of TGEV.

Animals↗
PubMed1996

Effect of dopamine antagonism on the behavioral and hemodynamic responses to cocaine in piglets.

Cocaine (1.5 mg/kg i.v.) was administered to awake newborn piglets that were pretreated with either intravenous saline (placebo) or SCH23390, a dopamine antagonist, to study dopamine's role in cocaine's vascular and behavioral actions. In the placebo group, cocaine increased the locomotor activity and cerebellar and cardiac blood flow (31 +/- 36 and 72 +/- 66%), but decreased choroid plexus and renal blood flow (47 +/- 23 and 18 +/- 19%). In the SCH23390-treated group, cocaine did not affect organ blood flow or locomotor activity. Cocaine transiently increased the mean arterial blood pressure in both groups (10 +/- 7 and 18 +/- 13%). These data indicate that the behavioral and blood flow responses to cocaine in cerebellum, choroid plexus, heart, and kidneys are mediated by dopamine, whereas the arterial pressor response to cocaine is not.

Animals↗
PubMed1996

Identification of protein kinase C isoforms in rat mesenteric small arteries and their possible role in agonist-induced contraction.

We have identified immunologically the protein kinase C (PKC) isoforms present in rat mesenteric small arteries, defined their distribution between particulate and soluble fractions, and studied their involvement in phorbol ester-induced contraction. Our analysis revealed the presence of the CA(2+)-dependent PKCs (alpha and gamma), Ca(2+)-independent PKCs (delta and epsilon), and the atypical isoform (zeta). PKCbeta could not be detected, whereas PKCgamma is likely to be of neural origin. All isoforms exhibited different distributions. PKCalpha, PKCepsilon, and PKCzeta were found in both particulate and soluble fractions. In contrast, PKCdelta was mainly in the particulate fraction, and PKCgamma was in the soluble fraction. Phorbol esters, which activate PKC and cause smooth muscle contraction, downregulated only the alpha and delta isoforms. This was associated with a parallel loss of contractile response to phorbol ester. The force developed to submaximal concentrations of noradrenaline was decreased after phorbol dibutyrate pretreatment, although the sensitivity and maximal response were unchanged. Phorbol ester pretreatment did not affect the contractile response to vasopressin. The sensitivity to non-receptor-mediated contraction, caused by k+ in the presence of prazosin, was slightly reduced by 4 alpha- and 4 beta-phorbol ester pretreatment. Maximal tension in response to this agonist was not affected. We conclude that PKCalpha and/or PKCdelta is necessary for phorbol ester-mediated contraction but is not essential for noradrenaline-, vasopressin-, or k(+)-induced contraction, demonstrating differences in the mechanisms involved in the contractile response between these agents.

Animals↗
PubMed1996

Effects of the Booroola gene (FecB(B)) on bodymass, testis development and hormone concentrations during fetal life.

In female fetuses the Booroola gene (FecB(B)) is known to affect germ cell development and consequently the pattern of ovarian follicular growth during fetal and post-natal life. However in males, the role of this gene during fetal development is unknown. The aims of the study reported here were to examine the effects of the FecB(B) gene on development of male fetuses with respect to body and organ mass for example, pituitary gland, adrenal and mesonephros), testes development, including numbers of germ cells, and also the plasma concentrations or tissue contents of the reproductive hormones (FSH, LH and testosterone) at days 40, 55, 75, 90 and 135 of gestation. The FecB(B) gene was found to influence litter size, bodymass, crown-rump length and testis mass at most stages of gestation. Some effects were also noted on the mesonephros at days 40 and 55 and on the pituitary and adrenal at days 90 or 135 of gestation. However, the FecB(B) gene was not observed to have an effect on the patterns of germ cell development, on pituitary content or plasma concentrations of immunoreactive or bioactive FSH or immunoreactive LH or testicular content of testosterone. When embryo transfer experiments were performed to eliminate the effects of litter size at days 40, 90 and 135 of gestation nearly all of the differences in bodymass, crown-rump length and organ mass disappeared. The only exception to this was at day 90 when bodymass continued to be lighter and crown-rump lengths smaller in the BB/B + fetuses compared with the +2 fetuses; the significance of this finding remains unknown. It is concluded that for Booroola male fetuses there are no direct effects of the FecB(B) gene on pituitary gonadotrophin function or testicular development after sexual differentiation. Moreover, although there may be temporal differences around day 90 of gestation, there are no long-term, direct effects of the FecB(B) gene on total body, adrenal, testis or pituitary mass. Collectively these findings for the male are similar to those for female fetuses except with regard to germ cell development.

Adrenal Glands↗
PubMed1995

Trends in coronary heart disease risk factors in Auckland 1982-94.

AIMS: This paper describes trends in major coronary heart disease risk factors over the period 1982 to 1994 in the city of Auckland, New Zealand. METHODS: Coronary heart disease risk factor levels were measured in three cross-sectional surveys in Auckland in 1982, 1986-8 and 1993-4, following a standardised protocol. Random samples of nonMaori, nonPacific Island adults aged 35-64 years were selected from the Auckland general electoral rolls using similar methods in all three surveys. Participants attended a study centre for interview and risk factor measurement. RESULTS: The analyses presented are based on samples of 1029 men and 569 women in 1982, 541 men and 365 women in 1986-8, and 712 men and 685 women in 1993-4. The data are directly age-standardised to the 1986 New Zealand population. Over the 12 year period the prevalence of self-reported cigarette consumption declined significantly from 28.6% to 16.9% in men and from 24.5% to 14.8% in women. Mean serum total cholesterol showed little change between 1982 and 1986-8 but declined significantly between 1986-8 and 1993-4 by approximately 6% from 6.12 mmol/L to 5.73 mmol/L in men and by 9% from 6.17 mmol/L to 5.60 mmol/L in women. Mean serum high density lipoprotein (HDL) cholesterol showed a modest increase between 1982 and 1986-8 but declined significantly between 1986-8 and 1993-4 by 12% from 1.25 mmol/L to 1.10 mmol/L in men and by 9% from 1.55 mmol/L in women to 1.40 mmol/L in women. The total cholesterol to HDL cholesterol ratio increased significantly between 1986-8 and 1993-4 by 6% in men but showed little change in women. Mean blood pressure levels fell by 4-6 mmHg systolic and 6-7 mmHg diastolic over the 12 year period in men and women. Mean body mass index increased significantly from 25.6 to 26.4 in men and from 24.5 to 25.1 in women during this period. CONCLUSIONS: Over the 12 year period, 1982-94 there have been substantial reductions in the prevalence of self reported cigarette smoking, mean serum total cholesterol levels and mean blood pressure levels in middle aged Aucklanders. Of concern, the prevalence of obesity has increased and mean serum HDL cholesterol levels have fallen over the period. Coronary heart disease prevention and control programmes appear to have been successful in reducing the prevalence of most major coronary heart disease risk factors however some reorientation will be required to redress the adverse trends in HDL cholesterol levels and obesity.

Adult↗
PubMed1995

Early and 1-year clinical outcome of patients' evolving non-Q-wave versus Q-wave myocardial infarction after thrombolysis. Results from The TIMI II Study.

BACKGROUND: There are few data comparing clinical outcome and potential indications for routine post-myocardial infarction cardiac catheterization and revascularization of patients who sustain a non-Q-wave versus Q-wave infarct after thrombolytic therapy. METHODS AND RESULTS: A secondary analysis of 2634 patients enrolled in the TIMI II trial with a first myocardial infarction was performed to determine 6-week and 1-year cardiac event rates and identify clinical and angiographic differences between the 1867 patients (70.9%) who evolved a Q-wave infarct and the 767 patients (29.1%) who sustained a non-Q-wave infarct after treatment with intravenous thrombolytic therapy. Male sex (85.3% versus 75.6%; P < .001) and anterior wall infarcts (53.8% versus 43.7%; P < .001) were more frequent in the Q-wave versus the non-Q-wave group. During recombinant tissue-type plasminogen activator (rTPA) infusion, a greater percentage of non-Q-wave patients (37.3% versus 23.5%; P = .001) had normalization of initial ST-segment elevation. Infarct-related artery patency (TIMI flow grade 2 or 3) (P = .02), complete infarct-related artery reperfusion (TIMI 3 flow grade) (P < .001), and the percentage of patients with a predischarge resting left ventricular ejection fraction > 55% (P < .001) were greater in the non-Q-wave group. New congestive heart failure during hospitalization developed more frequently in Q-wave patients (18.9% versus 11.6%; P < .001). After 42 days, the occurrences of reinfarction (P = .76), death (P = .76), and combined death or reinfarction (P = .43) were similar in patients assigned to the invasive or conservative postlytic management strategy, regardless of infarct type. One-year mortality was 3.4% versus 4.4% for non-Q-wave versus Q-wave infarct type, respectively (P = .25). CONCLUSIONS: Angiographic and clinical differences were observed between patients who present with initial ST-segment elevation and evolve early non-Q-wave versus Q-wave myocardial infarcts after treatment with rTPA, heparin, and aspirin. Early mortality and adverse clinical cardiac events in these patients are not significantly different after a conservative compared with an invasive treatment strategy, regardless of whether the infarct type is non-Q wave or Q wave.

Angioplasty, Balloon, Coronary↗
PubMed1995

Variation in patient utilities for outcomes of the management of chronic stable angina. Implications for clinical practice guidelines. Ischemic Heart Disease Patient Outcomes Research Team.

OBJECTIVE: Although practice guidelines sometimes make recommendations based on symptom severity, they rarely account for how patients feel about their symptoms. To investigate the possible importance of patient preferences in treatment of ischemic heart disease, we assessed attitudes toward symptoms in patients with angina pectoris. DESIGN: Case series. SETTING: Ambulatory cardiology clinics at two tertiary care medical centers. PATIENTS: A total of 220 subjects were selected from 589 patients with chronic stable angina referred from cardiologists to achieve patients samples balanced for sex, race, and angina severity. MAIN OUTCOME MEASURES: We measured patients' attitudes toward their angina using the rating scale, time trade-off, and standard gamble utility metrics. Reliability of measurements was evaluated by repeating the assessments 2 weeks later on 50 willing patients. RESULTS: While the mean responses followed the expected patterns (those with more severe Canadian Cardiovascular Society scores chose lower utilities), attitudes toward symptoms varied substantially among patients with similarly severe angina. For example, there was a 33% chance that a patient with class II angina had a time trade-off utility that was lower (ie, more bothered by symptoms) than a patient with more severe angina (class III/IV). This variation in utilities was not due to random error in the assessments. CONCLUSIONS: Angina patients with similar functional limitation vary considerably in their tolerance for their symptoms, as measured by utilities. Our findings suggest that guidelines for the management of ischemic heart disease should be based on the preferences of the individual patient rather than on symptom severity alone.

Adult↗
PubMed1995

Dental erosion.

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Beverages↗