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R Brant

Publications and source records attributed to R Brant.

At least 55 records · Page 3Linked to original sources
PubMed1994

Hypoxia similarly impairs metabolic responses to cutaneous and core cold stimuli in conscious rats.

Cold exposure elicits several thermoregulatory responses, including an increased metabolic heat production from shivering and nonshivering thermogenesis. The increased metabolism can be in response to body core and/or body cutaneous cooling. Hypoxic hypoxia has been shown to attenuate the metabolic response to cutaneous cooling. We measured metabolic heat production in adult conscious rats during independent cutaneous and core cooling, during normoxia and hypoxia, to 1) test the hypothesis that hypoxia suppresses the metabolic response to independent core cooling and 2) determine whether hypoxia acts preferentially on the response to cutaneous or core cooling. The animals were studied in a temperature-controlled metabolic chamber, and body core temperature was controlled by an abdominal heat exchange coil. Ambient temperature was varied (10, 19, and 28 degrees C) while core temperature was clamped at 37 degrees C or core temperature was varied (33, 35, and 37 degrees C) at a stable ambient temperature of 28 degrees C. Our data indicate that although the sensitivity of the metabolic response to core cooling is about five to six times that to cutaneous cooling. Hypoxia similarly attenuates thermoregulatory responses to both stimuli.

Animals↗
PubMed1994

Likelihood ratios for a sleep apnea clinical prediction rule.

Nocturnal polysomnography, the standard diagnostic test for sleep apnea, is an expensive and limited resource. In order to help identify the urgency of need for treatment, we determined which clinical features were most useful for establishing an accurate estimate of the probability that a patient had sleep apnea. Of 263 physician-referred patients, 200 were eligible for the study and 180 (90%) completed it. All patients had their histories recorded with a standard questionnaire, and underwent anthropomorphic measurements and nocturnal polysomnography. Sleep apnea was defined as more than 10 episodes of apnea or hypopnea per hour of sleep. Multiple linear and logistic regression models predictive of sleep apnea were compared with physicians' subjective impressions and previously reported models. Likelihood ratios were calculated for several levels of a sleep apnea clinical score produced by one of the linear models. Predictors of sleep apnea in the final model (R2 = 0.34) included neck circumference, hypertension, habitual snoring, and bed partner reports of nocturnal gasping/choking respirations. This model was superior to physician impression, slightly inferior to more detailed linear and logistic models, and comparable to previously reported models. A sleep apnea clinical score of less than 5 had a likelihood ratio of 0.25 (95% CI: 0.15 to 0.42) and a corresponding posttest probability of 17%, while a score of greater than 15 had a likelihood ratio of 5.17 (95% CI: 2.54 to 10.51) and posttest probability of 81%. These likelihood ratios can simply and accurately determined the probability of whether a patient has sleep apnea.

Adult↗
PubMed1994

The P1 blood group and the severity of diarrhea-associated hemolytic uremic syndrome.

Thirty-one children with diarrhea-associated hemolytic uremic syndrome were retrospectively studied to determine if expression of the P1 blood type was related to the severity of the acute illness or to the prognosis. No differences were found in the clinical variables studied in the patients who were P1 positive compared to the patients who were P1 negative. The clinical variables studied included the age, hemoglobin, white blood cell count (WBC), and presence of central nervous system involvement at presentation, the duration of elevated WBC, thrombocytopenia, hemorrhagic colitis, and anuria, and the follow-up incidence of proteinuria, hypertension and decreased GFR. Expression of the P1 phenotype does not appear to exert a protective influence in patients with D+ HUS.

Child, Preschool↗
PubMed1993

Relationship of the recovery in the glomerular filtration rate to the duration of anuria in diarrhea-associated hemolytic uremic syndrome.

The relationship of the duration of anuria to the recovery in glomerular filtration rate (GFR) was studied in 71 children with diarrhea-associated hemolytic uremic syndrome. A significant relationship was found, and regression analysis revealed that y = 114.61 - 5.68 x, where y is predicted GFR (ml/min/1.73 m2) and x is the square root of the duration of anuria in days. The presence of hypertension or proteinuria on follow-up was significantly related to the duration of anuria (p = 0.005 and p = 0.002, respectively).

Anuria↗
PubMed1993

Diarrhea-associated hemolytic uremic syndrome.

Diarrhea-associated hemolytic uremic syndrome (D+ HUS) is the most common cause of acute renal failure in children. The authors report their experience with D+ HUS with 114 patients assessed in Calgary from 1980 to 1992. Epidemiologic, clinical, and pathologic aspects are discussed.

Adolescent↗
PubMed1992

Comparison of plain with pH-adjusted bupivacaine with hyaluronidase for peribulbar block.

Fifty patients scheduled for cataract surgery under peribulbar block were randomised to receive either plain (pH 5.4) or pH-adjusted (pH 6.8 range 6.7-6.9) 0.75% bupivacaine. Hyaluronidase was added to both solutions prior to peribulbar block. The time of onset of akinesia of the globe and the need for supplementary injections were recorded by an independent observer. Patients who returned for surgery to the second eye received the alternative local anaesthetic solution for the second peribulbar block. The relative efficacy of the different anaesthetic solutions was compared in patients who underwent unilateral surgery (Group A, n = 50). In 12 patients (Group B) who underwent bilateral surgery, direct comparisons between eyes in the same patient were possible. In both groups of patients, eyes receiving peribulbar block with the pH-adjusted solution showed a shorter time to partial akinesia of the globe (P less than 0.05). However, there was no difference between the solutions in the time to complete akinesia of the globe, but the number of supplementary injections required for an effective block with the pH-adjusted solution was increased. Onset time to akinesia of the lateral and superior rectus muscles was shortened in patients receiving the pH-adjusted solution but there were minimal effects on the medial and inferior recti.

Anesthesia, Local↗
PubMed1992

Optimal therapeutic level of heparin therapy in patients with venous thrombosis.

BACKGROUND: Audits of heparin sodium therapy suggest that heparin administration is fraught with difficulty. The literature indicates that the current clinical practice of intuitive ordering of heparin results in inadequate therapy because of fear of bleeding. The importance of exceeding the lower limit of the therapeutic range has been strongly supported by findings of prospective clinical trials. Firm evidence indicates that failure to exceed the lower limit is associated with unacceptably high rates of recurrent venous thromboembolism. By comparison, evidence supporting the risk of exceeding the upper limit of the therapeutic range is weak. OBJECTIVES: The purposes of this study were (1) to validate prospectively an approach designed to minimize the proportion of patients receiving subtherapeutic doses of heparin and (2) to determine the effectiveness and safety of decreasing the heparin dosage infused on the basis of activated partial thromboplastin time (APTT) prolongation reflecting both heparin and warfarin sodium effects. METHODS: We performed a randomized double-blind study evaluating a prescriptive approach to heparin administration in patients receiving heparin or heparin with warfarin. Thromboembolic and bleeding complications were objectively documented. RESULTS: Only 1% and 2% of patients had subtherapeutic heparin levels for 24 hours or more in the heparin and combined groups, respectively. Recurrent venous thromboembolism occurred infrequently in both groups (7%). Sixty-nine (69%) of 99 patients receiving combined therapy had supratherapeutic values, compared with 24 (24%) of 100 receiving heparin; bleeding complications occurred in 9% and 12%, respectively. CONCLUSIONS: Our findings demonstrate that no association exists between supratherapeutic APTT responses and bleeding, which is in direct contrast to the observed association between subtherapeutic APTT responses and recurrent venous thromboembolism.

Double-Blind Method↗
PubMed1990

Assessing proportionality in the proportional odds model for ordinal logistic regression.

The proportional odds model for ordinal logistic regression provides a useful extension of the binary logistic model to situations where the response variable takes on values in a set of ordered categories. The model may be represented by a series of logistic regressions for dependent binary variables, with common regression parameters reflecting the proportional odds assumption. Key to the valid application of the model is the assessment of the proportionality assumption. An approach is described arising from comparisons of the separate (correlated) fits to the binary logistic models underlying the overall model. Based on asymptotic distributional results, formal goodness-of-fit measures are constructed to supplement informal comparisons of the different fits. A number of proposals, including application of bootstrap simulation, are discussed and illustrated with a data example.

Biometry↗
PubMed1989

Diphtheria-tetanus overimmunization in children with no records: can it be prevented?

A pilot study was undertaken to assess the validity of two new tests for predicting the immune response of Toronto schoolchildren with no acceptable evidence of prior administration of diphtheria or tetanus toxoid to a routine booster injection of diphtheria and tetanus (DT) toxoid. The tests, an inexpensive enzyme-linked immunosorbent assay (ELISA) fingerprick test for tetanus antibodies and a modification of the Schick skin test for susceptibility to diphtheria, were administered before the booster injection. One week later the ELISA test was repeated and the result of the modified Schick test read. On both occasions a diphtheria microneutralization assay was done for "gold standard" evidence of prior exposure to diphtheria toxoid or toxin. The results were used to determine the sensitivity and specificity of a single prebooster tetanus ELISA test or a modified Schick test for predicting which children with no records could be safely protected with only one DT booster dose instead of the primary series of three or four doses usually given to such children. Only 6 of the 34 subjects (18%) were totally without prior exposure to tetanus toxoid. Two of the six (6% of 33 subjects) appeared to mount a primary immune response to diphtheria toxoid as well. An initial ELISA titre of 0.01 IU/ml or lower correctly identified all six children needing a full series of tetanus toxoid (sensitivity for a primary immune response 100%) and falsely identified only 3 of 28 immune children as needing the series (specificity for immunity 89.3%). The modified Schick test appeared to have even greater accuracy for identifying children needing a full series of diphtheria toxoid. However, its use, entailing the costs of an extra nurse visit, would have prevented only seven more children from receiving an unnecessary full series of diphtheria toxoid than use of the baseline tetanus ELISA test alone.

Adolescent↗
PubMedDate not supplied

Sexual abuse of children in day care centers.

Sexual abuse of children in day care center settings has received considerable attention in the past decade. The nature and extent of allegations of sexual abuse in day care poses unique challenges to clinicians. Cases of sexual abuse in day care typically involve multiple victims and multiple perpetrators, and use of extreme threats to prevent disclosure. This article reviews the available research findings on the types of abuse known to occur in day care, the dynamics involved including the types of threats used to silence young victims, and patterns of disclosure. The impact of sexual victimization in day care on children and parents is discussed. Implications for the clinical evaluation of preschool-aged children in cases of suspected abuse in day care settings are presented. Developmental considerations related to psychosexual development and the development of memory and language are reviewed. Psychological defenses in repetitive trauma are discussed.

Child↗
PubMedDate not supplied

Hexachlorobenzene exposure and the proportion of male births in Turkey 1935-1990.

Hexachlorobenzene (C(6)Cl(6), HCB) is a chemical that has been associated with significant immediate and long term adverse health effects in humans. It has been associated with both porphyria cutanea tarda and spontaneous abortions among survivors of widespread exposure in the 1950s in southeastern Turkey. HCB binds to the Ah receptor, albeit with lower affinity than dioxin. Dioxin exposure has been reported to lower human secondary sex ratio, putatively through a male mediated effect. We therefore wished to evaluate the impact of the HCB environmental event on the sex ratio of the progeny of the survivors. We undertook an assessment of 1) the effects of HCB exposure on the proportion of male births of individual subjects who had survived, 2) variables that significantly predicted the proportion of males among these individuals, and 3) the trend of the population sex ratio born in Turkey from 1935 to 1990. Women known to have been exposed to HCB in the 1950s did not have offspring with a significantly different sex ratio when compared to control populations. However, subjects reporting exposure at the peak of the episode (1955-57) had a significantly lower lifetime proportion of males than those exposed at a later date. The lifetime reported spontaneous abortion rate of these women also significantly predicted the percent males per subject. The available national data demonstrated a significant reduction in the calculated proportion of males from 1935 to 1970 that stabilized from 1970 to 1990. These data indicate that HCB exposure that was sufficient to induce clinical porphyria cutanea tarda may also have reduced the proportion of males in subjects over their reproductive life-span. The HCB episode does not explain the pattern of the national trend from a population perspective.

Abortion, Spontaneous↗
PubMedDate not supplied

Evaluation of reproductive outcomes in women inadvertently exposed to hexachlorobenzene in southeastern Turkey in the 1950s.

In southeastern Turkey during the period of 1955-57, women were accidentally exposed to the fungicide hexachlorobenzene (HCB) after eating contaminated seed grain and developed porphyria cutanea tarda (PCT). While HCB has been shown to be a potent oocyte toxicant in primates and has been identified as an ovarian follicular fluid contaminant in women, its effect on human reproduction is poorly understood. This study was undertaken to evaluate the effects of HCB on women with a known high dose exposure. A retrospective controlled cohort comparison study of three groups was conducted. Group 1, those with confirmed PCT; Group 2, controls for the region and Group 3, controls for the country of Turkey, were followed-up after approximately 40 years (n=42/group). Blood samples were taken for analysis of serum HCB, estradiol, follicle-stimulating hormone (FSH) and inhibin. Frequency of HCB detection was greatest in Group 3, while number of cases with HCB values exceeding 1 ng/mL was significantly greater in Groups 1 and 2. There were no differences in the other biochemical measures. Interviews were completed for each patient regarding reproductive history (number of pregnancies, live births, spontaneous abortions, still births and sex of live babies). Multiple comparisons of the three groups, based on Fisher's test found the groups were inhomogeneous. When serum HCB was analyzed using correlated response logistic regression, there was a strong relationship between serum HCB levels and risk for spontaneous abortion but not sex ratio of children. The following findings were made. HCB is detectable and ubiquitous in serum samples from women in the country of Turkey with identified and unidentified exposure events. Spontaneous abortion risk is not restricted to women with identifiable exposure to HCB but to a surrogate marker of exposure (serum HCB sample). The risk of spontaneous abortion with HCB exposure requires further investigation.

Abortion, Spontaneous↗
PubMedDate not supplied

The relationship between COMT genotype and the clinical effectiveness of tolcapone, a COMT inhibitor, in patients with Parkinson's disease.

Patients with Parkinson's Disease (PD) have a variable response to tolcapone, a catechol-O-methyltransferase (COMT) inhibitor. In addition, a subset of patients develop severe diarrhea as a side effect. Two codominant alleles for the COMT gene exist, coding for low and high activity, resulting in low-, medium-, and high-activity genotypes. This study investigates the relationship between this variation in genotype and clinical effects in patients with PD taking tolcapone. To investigate the relationship between COMT polymorphism and clinical response, 24 patients who completed tolcapone clinical trials provided blood samples for COMT genotype analysis. Change in levodopa dose and United Parkinson Disease Rating Scale (UPDRS) Part III (motor subscale) were analyzed at baseline, at 1-2 weeks, and 6 months after initiation of tolcapone. Genotype analysis was performed on seven patients who had diarrhea as a side effect. There was no significant correlation between genotype and improvement in UPDRS score (p = 0.29) according to a linear models approach that adjusted for the subject's severity of PD, tolcapone dose (either 100 or 200 mg three times daily) and initial differences in baseline scores. No significant difference was seen in change in daily levodopa intake and genotype. There was also no relation between diarrhea and COMT genotype. These results indicate that, in the treatment of Parkinson's disease, COMT genotype is not a major contributor to the clinical response to tolcapone.

Aged↗