Biomedical subjects

R G Hoffmann

Publications and source records attributed to R G Hoffmann.

At least 37 records · Page 2Linked to original sources

PubMed1997

Low-density lipoprotein particle size is not a discriminating marker for atherogenic risk in male offspring of parents with early coronary artery disease.

The aim of this study was to assess the importance of low-density lipoprotein (LDL) particle size as a marker of atherogenic risk in male offspring of a parent with early coronary artery disease (CAD) before the age of 60 years. CAD-positive (CAD+) offspring were recruited into two groups based on age, 15 to 30 years (n = 20) and 31 to 45 years (n = 41), and matched to CAD-negative (CAD-) offspring by age and body mass index (BMI) (n = 20 and 21 per group). LDL peak particle diameter was assessed by polyacrylamide gradient gel electrophoresis. There was no significant difference in LDL peak particle diameter between CAD+ and CAD- offspring (26.2 +/- 0.1 v 26.2 +/- 0.1 nm, mean +/- SE). There was also no difference between CAD+ offspring and CAD- offspring when comparisons were made within their own age group (26.5 +/- 0.1 nm in younger CAD+ offspring v 26.2 +/- 0.1 nm in younger CAD- offspring, and 26.0 +/- 0.1 nm in older CAD+ offspring v 26.1 +/- 0.2 nm in older CAD- offspring). Peak particle diameter was significantly greater in younger CAD+ offspring than in older CAD+ offspring (26.5 +/- 0.1 v 26.0 +/- 0.1 nm, P < .05). We conclude that small LDL particle size is not a discriminating marker for early atherogenic risk, and that measurement of LDL particle size has limited value in the assessment of coronary risk, at least in the age ranges we studied.

Adolescent↗

PubMed1997

Decreased glucose tolerance, not decreased insulin sensitivity, is a maturational abnormality in the male offspring of a parent with early coronary artery disease.

We investigated whether the male offspring of a parent with early coronary artery disease (before the age of 60; n = 61) exhibit decreased insulin sensitivity compared with controls matched for age and body mass index (BMI) (n = 39). The insulin sensitivity index (S[I]) was determined by the minimal modeling method of Bergman from a frequently sampled intravenous glucose tolerance test with intravenous tolbutamide. Offspring and controls had a similar S[I], insulin-independent glucose utilization (S[G]), first-phase insulin response (AIR[G]), and area under the glucose curve. When subjects were separated into two age groups, younger subjects aged 15 to 30 years and older subjects aged 31 to 45 years, important differences were seen. S[G] was significantly increased in younger offspring compared with controls (22.8 +/- 2.3 v 16.8 +/- 2.3 x 10(-3) x min(-1), P < .05). Older offspring had a significantly increased area under the glucose curve compared with controls (18,250 +/- 322 v 17,225 +/- 347 mg/dL x min(-1), P < .05). Older offspring also had decreased S[I] compared with younger offspring (5.0 +/- 0.4 v 6.6 +/- 0.9 x 10(-4) x min(-1) x micro U/mL, P < .05), but this difference was eliminated after adjusting for BMI and waist to hip ratio (5.5 +/- 0.4 v5.8 +/- 0.9 x 10(-3) x min(-1), nonsignificant). This study does not support the concept that insulin resistance is an early atherogenic risk factor in offspring at risk for coronary disease because of their family history. However, it does point to the importance of maturational changes in glucose homeostasis in these offspring.

Adolescent↗

PubMed1997

Insulin resistance is not a major determinant of low-density lipoprotein particle size.

The relationship between low-density lipoprotein (LDL) peak particle diameter and insulin sensitivity, very-low-density lipoprotein (VLDL) + intermediate-density lipoprotein (LDL) triglyceride, cholesterol, and apoprotein B, postprandial lipemia, and LDL + high-density lipoprotein (HDL) triglyceride was assessed. The subjects were 101 healthy males aged 15 to 45 years. Sixty-one subjects (60.4%) were offspring of a parent with coronary artery disease before age 60, and 40 subjects (39.6%) had no parental history of coronary artery disease. LDL peak particle diameter was measured following polyacrylamide gradient gel electrophoresis. An insulin sensitivity index (Si) was determined from a frequently sampled intravenous glucose tolerance test using a minimal modeling method. A fat tolerance test was performed with a test meal containing 70 g/m2 fat, with triglyceride concentrations measured hourly for 12 hours. LDL peak particle diameter was significantly correlated with body mass index (BMI) (r = -.282, P < .01), waist to hip ratio (r = -.291, P < .01), fasting triglyceride (logarithmically [log] transformed) (r = -.566, P < .001), area under the postprandial triglyceride curve (log transformed) (r = -.562, P < .001), VLDL + IDL triglyceride (log transformed) (r = -.462, P < .001), VLDL + IDL cholesterol (log transformed) (r = -.477, P < .001), VLDL + IDL apoprotein B (log transformed) (r = -.321, P < .001), LDL + HDL triglyceride (log transformed) (r = .583, P < .001), and HDL cholesterol (r = .347, P < .001), but there was no significant correlation with Si. Using stepwise regression analysis, LDL + HDL triglyceride showed the strongest relationship to LDL peak particle diameter, accounting for 34% of the variation in size. Si was not an independent predictor of LDL particle size. In conclusion, insulin sensitivity appears to have little influence on LDL particle size. The importance of LDL + HDL triglyceride should be considered a preliminary finding warranting verification in this and other populations.

Adolescent↗

PubMed1997

Actions of phenylephrine, isoproterenol, and epinephrine with halothane on endocardial conduction and activation in canine left ventricular papillary muscles.

BACKGROUND: Myocardial sensitization by halothane to the arrhythmogenic effects of epinephrine involves synergistic actions mediated by alpha 1- and beta-adrenoceptors. Halothane potentiates a transient a1-adrenoceptor-mediated negative dromotropic effect of epinephrine on Purkinje fibers. This study examines how halothane alters the actions of alpha 1- and beta-agonists and epinephrine on endocardial conduction. METHODS: Superfused canine papillary muscles were mapped to locate a Purkinje-ventricular muscle junction (PVJ), and bipolar electrodes were placed to measure Purkinje and endocardial conduction velocity and PVJ conduction time during stimulation of the Purkinje layer. The effects of exposure to 5 microM phenylephrine, 1 microM isoproterenol, or 5 microM epinephrine on conduction were determined in the absence and presence of 0.4 mM halothane in three groups of 10 preparations. RESULTS: Isoproterenol slightly increased Purkinje conduction velocity and markedly improved conduction at the PVJ and in the endocardium similarly in the presence or absence of halothane. Phenylephrine depressed Purkinje velocity (-12%) only in the presence of halothane and did not slow conduction at the PVJ or in the myocardium. Epinephrine transiently depressed Purkinje velocity, more so with (-22%) than without (-12%) halothane (P < or = 0.01), and simultaneously facilitated conduction at the PVJ and in the myocardium. CONCLUSIONS: The prodysrhythmic actions of epinephrine with halothane may involve disparate effects on conduction, including speeding on conduction at the PVJ and in the myocardium, similar to that produced by isoproterenol, accompanied by simultaneous but transient alpha 1-mediated depression of conduction in the Purkinje system.

Adrenergic alpha-Agonists↗

PubMed1997

A highly sensitive enzyme-linked immunosorbent assay for the detection of circulating anti-BP180 autoantibodies in patients with bullous pemphigoid.

The BP180 antigen, a component of the epidermal anchoring complex, has been identified as one of the major antigenic targets of autoantibodies associated with the blistering skin disease, bullous pemphigoid. Our research group has recently demonstrated that reactivity of bullous pemphigoid autoantibodies to the BP180 ectodomain is almost entirely restricted to a set of four antigenic sites clustered within the membrane-proximal noncollagenous stretch (NC16A). Using a passive transfer mouse model, antibodies to the corresponding noncollagenous region of murine BP180 were shown to trigger an inflammatory subepidermal blistering disease that closely mimics bullous pemphigoid. We now report the development of an enzyme-linked immunoabsorbent assay system that is extremely sensitive in detecting disease-specific autoantibodies in the sera of bullous pemphigoid patients. The target antigen in this assay is a recombinant form of the BP180 NC16A domain that contains all four of the well-defined bullous pemphigoid-associated antigenic sites. Of 50 randomly selected bullous pemphigoid sera tested, 47 (94%) were positive in this assay, whereas no specific reactivity was detected in any of the 107 controls. Interestingly, all three of the bullous pemphigoid sera that were negative in this assay had been obtained from patients who were already undergoing treatment. The NC16A enzyme-linked immunosorbent assay is more sensitive than any of the standard techniques for detecting circulating bullous pemphigoid autoantibodies, including other enzyme-linked immunosorbent assays, immunoblotting, and indirect immunofluorescence. Finally, the NC16A enzyme-linked immunosorbent assay provides immunologic information that cannot be obtained from direct immunofluorescence studies of skin biopsies, and that may well be relevant in the diagnosis and treatment of bullous pemphigoid.

Autoantibodies↗

PubMed1997

Augmentation of deglutitive upper esophageal sphincter opening in the elderly by exercise.

Earlier studies have shown that the cross-sectional area of the deglutitive upper esophageal sphincter (UES) opening in healthy asymptomatic elderly individuals is reduced compared with healthy young volunteers. The aim of this study was to determine the effect of a head-raising exercise on swallow-induced UES opening and hypopharyngeal intrabolus pressure in the elderly. We studied a total of 31 asymptomatic healthy elderly subjects by videofluoroscopy and manometry before and after real (19 subjects) and sham (12 subjects) exercises. A significant increase was found in the magnitude of the anterior excursion of the larynx, the maximum anteroposterior diameter, and the cross-sectional area of the UES opening after the real exercise (P < 0.05). These changes were associated with a significant decrease in the hypopharyngeal intrabolus pressure studied in 12 (real-exercise) and 6 (sham-exercise) subjects (P < 0.05). A similar effect was not found in the sham-exercise group. In normal elderly subjects, deglutitive UES opening is amenable to augmentation by exercise aimed at strengthening the UES opening muscles. This augmentation is accompanied by a significant decrease in hypopharyngeal intrabolus pressure, indicating a decrease in pharyngeal outflow resistance. This approach may be helpful in some patients with dysphagia due to disorders of deglutitive UES opening.

Aged↗

PubMed1997

Incorporating socio-economic and risk factor diversity into the development of an African-American community blood pressure control program.

OBJECTIVE: To develop culturally competent community based blood pressure control programs for inner-city African Americans. DESIGN: Cross sectional study of randomly selected households from three experimental and three control communities. SETTING: Very low, moderately low and moderate socio-economic status (SES) inner-city communities in Chicago, Illinois. PARTICIPANTS: 957 African Americans adults, aged 18 and over from target communities. MAIN OUTCOME MEASURE: Household health assessments included employment, education and other demographic information, history of hypertension, disease prevalence, health behaviors, risk factor prevalence, stress, coping/John Henryism, social support, health care utilization and standardized assessments of blood pressure, height, and weight. RESULTS: There were no significant gender differences in blood pressure levels. Men had more hypertension than women, and women in the very low SES community had significantly more hypertension than women in the moderately low SES community. There was significantly more hypertension overall in the moderately low SES community. Age, education and BMI were the only factors significantly associated with systolic and diastolic blood pressure in all three communities. The very low SES community had significantly more obesity and more uninsured persons than the other communities. CONCLUSIONS: Intraracial diversity is an important factor to be considered in the development of community blood pressure control programs for African Americans. Age, gender, educational background and SES play a major role in influencing health behaviors and access to health care.

Adolescent↗

PubMed1996

Circadian variation in sudden cardiac death: effects of age, sex, and initial cardiac rhythm.

STUDY OBJECTIVE: Previous studies based on data obtained from vital statistics records have demonstrated circadian variation in the occurrence of sudden cardiac death. The purpose of this study was to examine the effects of age, sex, and initial cardiac rhythm on circadian variability in sudden cardiac death. METHODS: This study employed a retrospective analysis of the records of adult patients with witnessed cardiac arrest who underwent resuscitation in an urban paramedic system during a 5-year period. RESULTS: The records of 2,250 consecutive patients with witnessed cardiac arrest were reviewed. Spectral analysis was used to decompose the data into frequency components. A circadian variation in the occurrence of sudden cardiac death was demonstrated, with a low occurrence rate between midnight and 6 AM and a 2.4-fold increase between the rate at 6 AM and the rate at noon. The same circadian pattern was noted among both men and women, among both patients aged 18 to 70 and those older than 70 years, and among patients with various initial cardiac arrest rhythms (ventricular tachycardia or fibrillation, asystole, and electromechanical dissociation). However, the outcome of resuscitation in these patients (ie, the rate of successful resuscitation and the rate of survival) did not demonstrate circadian variation. CONCLUSION: Witnessed out-of-hospital sudden cardiac death demonstrated circadian variation, and this variability was observed regardless of the patient's age, sex, or initial cardiac arrest rhythm. The outcome of resuscitation did not show circadian variability. These results suggest a common pathophysiologic mechanism leading to sudden cardiac death.

Adolescent↗

PubMed1996

Urinary oxalate excretion increases with body size and decreases with increasing dietary calcium intake among healthy adults.

Increasing dietary calcium intake decreases urinary oxalate excretion by increasing intestinal precipitation of dietary oxalate as calcium oxalate. This mechanism was speculated to account for the decreased prospective incidence of kidney stones as estimated dietary calcium intake, adjusted for caloric intake, increased among men in a recent large epidemiological study. To further assess the relationship between estimated diet calcium and urinary oxalate, we studied 94 health adults, 50 women and 44 men, ages 20 to 70 years with weights ranging form 47 to 104 kg while they ate their customary diets. Each subject completed a semiquantitative food frequency questionnaire and collected three 24-hour urines preserved with HCl. The urines were collected accurately as judged by a mean intrasubject CV for creatinine excretion of 9.8% and direct relations between urinary creatinine excretion and body wt (r = 0.62; P < 0.0001), or predicted urine creatinine content for sex, age and weight using the Cockcroft and Gault formulas (r = 0.76; P < 0.0001). Estimated diet calcium intake ranged from 6.8 to 68 mmol/day (272 to 2720 mg/day) and averaged 29.5 mmol/day (1180 mg/day). Individual mean urinary oxalate excretion ranged from 0.079 go 0.332 mmol/day (7 to 29 mg/day) and averaged 0.198 mmol/day (17 mg/day). Among all subjects, daily oxalate excretion was directly related to creatinine excretion as an estimate of lean body mass (r = 0.61; P < 0.0001). Thus, oxalate excretion among men averaged 0.228 +/- 0.051 SD mmol/day, a value significantly higher than the average among women of 0.173 +/- 0.045 mmol/day (P < 0.001). Daily urine oxalate excretion/creatinine decreased curvilinearly as estimated dietary Ca intake increased (r = -0.30; P = 0.0035) and as the ratio of estimated dietary calcium to dietary oxalate increased (r = -0.39; P = 0.0001). We conclude that body size is the major determinant of urinary oxalate excretion among healthy adults, presumably reflecting variations in endogenous oxalate synthesis with lean body mass. Increasing estimated diet calcium intake, especially up to the range of 15 to 20 mmol/day (600 to 800 mg/day) has an additional effect to decrease during oxalate excretion, presumably by limiting intestinal absorption of dietary oxalate.

Adult↗

PubMed1996

Epinephrine dysrhythmogenicity is not enhanced by subtoxic bupivacaine in dogs.

Since bupivacaine and epinephrine may both precipitate dysrhythmias, circulating bupivacaine during regional anesthesia could potentiate dysrhythmogenic effects of epinephrine. We therefore examined whether bupivacaine alters the dysrhythmogenicity of subsequent administration of epinephrine in conscious, healthy dogs and in anesthetized dogs with myocardial infarction. Forty-one conscious dogs received 10 micrograms.kg-1.min-1 epinephrine. Seventeen animals responded with ventricular tachycardia (VT) within 3 min. After 3 h, these responders randomly received 1 or 2 mg/kg bupivacaine or saline over 5 min, followed by 10 micrograms.kg-1.min-1 epinephrine. In the bupivacaine groups, epinephrine caused fewer prodysrhythmic effects than without bupivacaine. VT appeared in fewer dogs and at a later time, and there were more sinoatrial beats and less ectopies. Epinephrine shortened QT less after bupivacaine than in control animals. One day after experimental myocardial infarction, six additional halothane-anesthetized dogs received 4 micrograms.kg-1.min-1 epinephrine until VT appeared. After 45 min, 1 mg/kg bupivacaine was injected over 5 min, again followed by 4 micrograms.kg-1.min-1 epinephrine. In these dogs, the prodysrhythmic response to epinephrine was also mitigated by preceding bupivacaine. Bupivacaine antagonizes epinephrine dysrhythmogenicity in conscious dogs susceptible to VT and in anesthetized dogs with spontaneous postinfarct dysrhythmias. There is no evidence that systemic subtoxic bupivacaine administration enhances the dysrhythmogenicity of subsequent epinephrine.

Anesthetics, Local↗

PubMed1996

Measures of postural steadiness: differences between healthy young and elderly adults.

Measures of postural steadiness are used to characterize the dynamics of the postural control system associated with maintaining balance during quiet standing. The objective of this study was to evaluate the relative sensitivity of center-of-pressure (COP)-based measures to changes in postural steadiness related to age. A variety of time and frequency domain measures of postural steadiness were compared between a group of twenty healthy young adults (21-35 years) and a group of twenty healthy elderly adults (66-70 years) under both eyes-open and eyes-closed conditions. The measures that identified differences between the eyes-open and eyes-closed conditions in the young adult group were different than those that identified differences between the eye conditions in the elderly adult group. Mean velocity of the COP was the only measure that identified age-related changes in both eye conditions, and differences between eye conditions in both groups. The results of this study will be useful to researchers and clinicians using COP-based measures to evaluate postural steadiness.

Adult↗

PubMed1996

Effect of pioglitazone on vascular reactivity in vivo and in vitro.

Pioglitazone (a thiazolidinedione derivative) increases insulin sensitivity and prevents hypertension in the Dahl-salt-sensitive (S) rat. The present study was undertaken to determine if pioglitazone modulates pressor responsiveness to vasoactive agents, both in vivo and in vitro. In vivo, pretreatment with pioglitazone inhibited (P < 0.02) pressor responses to both norepinephrine and angiotensin II in conscious Dahl-S, but not in Sprague-Dawley rats. In vitro, pioglitazone augmented the capacity of insulin to inhibit pressor responses of strips of thoracic aortas to norepinephrine, but not to angiotensin. Additionally, in vitro, incubation with insulin plus pioglitazone augmented acetylcholine-induced, but not nitroprusside-induced vasodilation. Pioglitazone pretreatment increased (P < 0.001) in vitro insulin-stimulated glucose uptake in adipose tissue, but not in thoracic aortas of Dahl-S. We hypothesize that pioglitazone attenuates hypertension by modulating the effects of insulin on vascular function, resulting in both blunted vasoconstriction and augmented acetylcholine-induced vasodilation. These alterations are not accounted for by an effect of pioglitazone on glucose uptake by vascular smooth muscle.

Animals↗

PubMed1996

Leptin: a significant indicator of total body fat but not of visceral fat and insulin insensitivity in African-American women.

The recently cloned adipose tissue hormone leptin has been proposed to be involved in the neuroendocrine regulation of adiposity and its metabolic sequelae. Visceral fat is known to predict reduced insulin sensitivity and associated adverse metabolic profiles. In this study, we report the first evaluation of the relationships between leptin levels and total body fat, visceral fat, and insulin sensitivity in a cohort of premenopausal African-American women. Thirty-four subjects were analyzed for total fat mass and visceral fat by dual-energy X-ray absorptiometry and computerized axial tomography, respectively. Insulin sensitivity (SI) was assessed using Bergman's minimal model. Results showed that fasting leptin levels strongly correlated with total body fat mass (r = 0.797, P < 0.001). Correlations of leptin with visceral fat (r = 0.54, P < 0.001) and SI (r = -0.419, P = 0.02) were dependent on total body fat. In conclusion, leptin levels reflect total body fat mass, and although visceral fat is known to predict reduced insulin sensitivity independently, leptin did not. Our data thus suggest that diverse mechanisms are responsible for the regulation of total body versus visceral fat distribution, with its metabolic and health risks.

Adipose Tissue↗

PubMed1996

Perceptions of parenting stress and family relations by fathers of children evaluated for organ transplantation.

18 fathers of children evaluated for solid organ or bone marrow transplantation completed measures of parenting stress and family functioning. Comparisons with normative data indicated that these fathers reported less parenting stress, less family conflict, more concern about family finances, and more limitations in family activities. These data highlight the need for family-based assessments in pediatric transplantation.

Adult↗

PubMed1996

Mothers of children evaluated for transplantation: stress, coping resources, and perceptions of family functioning.

The stress, coping resources, and family functioning of 36 mothers of children awaiting transplantation were evaluated. Using standardized assessment techniques, we found that, overall, 20% of mothers reported clinically elevated stress responses and that parenting stress was higher for mothers of children evaluated for solid organ transplantation (vs. bone marrow transplantation). Coping strategies characterized by maintenance of personal and family stability were strongly associated with lower levels of parenting stress. Findings also showed significant disruption in family planning and activities, as well as a strong association between lower socioeconomic status and higher parenting stress. There is a need for the longitudinal assessment of parental and family functioning throughout the transplantation process as well as for interventions designed to reduce parenting distress.

Adaptation, Psychological↗

PubMed1995

Insulin sensitivity and antiandrogenic therapy in women with polycystic ovary syndrome.

Polycystic ovary (PCO) syndrome is strongly associated with insulin resistance and the accompanying adverse metabolic profile. To distinguish the mechanisms of this association, we determined the interactions of PCO with obesity and the influence of ameliorating direct androgenic actions via short-term treatment with the antiandrogen flutamide. Insulin sensitivity was determined by the hyperinsulinemic euglycemic clamp in groups of lean and obese PCO women and weight-matched controls. Compared with control values, insulin-mediated glucose utilization in PCO women was significantly lower in lean (1.96 +/- 0.17 v 1.24 +/- 0.10, P < .01) and obese (1.23 +/- 0.18 v 1.03 +/- 0.09 mmol/m2/min, P < .01) subjects. ANOVA indicated that the effects of obesity and androgenicity are independent and additive. In both lean and obese PCO women, treatment with flutamide for 1 or 3 months markedly improved the clinical and biochemical androgenic features, but did not significantly influence the overall insulin sensitivity. A large disparity between individuals in the response to treatment correlated significantly with a simultaneous reduction in plasma levels of dehydroepiandrosterone sulfate (DHEA-S). Thus in women, PCO and obesity exert synergistic effects on insulin resistance. The decreased insulin sensitivity is mediated via indirect androgenic actions or nonandrogenic mechanisms. In some individuals, a direct effect of androgens might have been masked by a decrease in DHEA-S levels.

Adolescent↗

PubMed1995

A subtype of alpha 1 adrenoceptor mediates depression of conduction in Purkinje fibers exposed to halothane.

BACKGROUND: An action of epinephrine at alpha adrenoceptors has been reported to slow conduction in Purkinje fibers exposed to halothane. In Purkinje fibers one pharmacologically distinguishable alpha 1-adrenoceptor subtype (alpha 1B) sensitive to the noncompetitive antagonist chloroethylcholinidine mediates decreases in automaticity. Another alpha 1 subtype (alpha 1A), sensitive to the competitive antagonist WB4101, increases spontaneous rate and action potential duration by a mechanism thought to involve hydrolysis of membrane phosphoinositides by phospholipase C. This study examined the dose-response relation and receptor-effector mechanisms underlying depression of conduction in canine Purkinje fibers by epinephrine with halothane. METHODS: Conduction velocity was determined in vitro by measuring the conduction time between action potentials recorded from two Purkinje fibers located about 6 mm apart along the length of free running portions of the ventricular conduction system, the false tendons. Velocity was evaluated at 1-min intervals during trials of rapid exposure to different agonists in groups of 6-12 preparations. RESULTS: Epinephrine (0.2-5.0 microM) transiently decreased Purkinje conduction velocity in a dose-related manner by as much as 33% (at 5 microM epinephrine with 0.86 mM (2.8%) halothane). Velocity decreased by 5% (P < or = 0.01) at an epinephrine concentration similar to "just-threshold" dysrhythmogenic plasma epinephrine concentrations (0.2 microM epinephrine with 0.46 mM halothane) reported in halothane-anesthetized dogs. The decreases of conduction velocity were blocked by prazosin but not by metoprolol, were produced by phenylephrine but not by clonidine, and were antagonized by equimolar (0.5 microM) concentrations of WB4101 more so (P < or = 0.01) than by chloroethylclonidine. WB4101 (0.1 microM) produced 87% inhibition of the response to 0.2 microM epinephrine after chloroethylclonidine pretreatment, indicating mediation by the alpha 1A subtype. Other agonists linked to cardiac phospholipase C activation, including endothelin 1 (40 nM) and the muscarinic agonist carbamylcholine (1 mM), also decreased conduction velocity in fibers exposed to halothane. CONCLUSIONS: Clinically relevant concentrations of epinephrine transiently depress conduction in Purkinje fibers exposed to halothane by activating cardiac alpha 1 adrenoceptors, largely but not exclusively the WB4101-sensitive alpha 1A subtype, reportedly coupled to stimulation of phospholipase C and generation of the second messengers diacylglycerol and inositol trisphosphate. Anesthetic potentiation of cardiac alpha 1-adrenoceptor effects may contribute to the generation of halothane-epinephrine dysrhythmias by abnormally slowing conduction and facilitating reentry.

Animals↗

PubMed1995

A study of intracranial volume in Apert syndrome.

The present study was undertaken to characterize the intracranial volume in patients with Apert syndrome. Radiographic and CT-based techniques for measuring intracranial volume were found to show close correlation when validated in dry normal adult skulls. A standard-deviation score of intracranial volume, determined from CT scans in 20 patients with Apert syndrome from birth to 30 years of age, was calculated with reference to a normative database of age- and sex-matched controls. Analysis of the data showed no significant difference in standard-deviation score between Apert patients with or without ventriculomegaly, before or after cranial vault surgery, or between male and female patients. The mean standard-deviation score among all Apert CT scans compared with normative data was 3.1, which was highly significant (p < 0.001). However, the growth curves showed no significant difference in intracranial volume between Apert and normal patients below 3.5 months of age. In summary, intracranial volume in Apert syndrome is within normal range at birth but increases to greater than 3 standard deviations above normal after 3.5 months of age, a finding independent of cranial vault surgery.

Acrocephalosyndactylia↗