[Two familial cases with exertion-induced heat stroke--relationship to malignant hyperthermia]

Two patients in a family of exertion-induced heat stroke were reported. Case 1: A 23-year-old male, paternal cousin of case 2, was admitted to our hospital because of loss of consciousness during running under a burning sun. On physical and neurological examinations, he was deeply comatose with high fever, tachycardia, and increased deep tendon reflexes. Laboratory findings disclosed rhabdomyolysis, acute renal failure, disseminated intravascular coagulation, liver injury, and brain edema. He recovered after intensive cooling, some antibiotics, glycerol and sodium dantrolene administration. Case 2: A 19-year-old male experienced loss of consciousness and high fever during playing soccer at 15 years of age, and was admitted to a hospital. On admission, he had high fever of 38.7 degrees C, and increased serum CK level. He recovered two weeks after admission. He was readmitted to our hospital to evaluate the predisposition for malignant hyperthermia. His physical and neurological examinations showed no abnormalities. Routine laboratory findings were within normal limits. Muscle biopsy findings of cases 1 and 2 were mildly increased number of fibers with centrally placed nuclei. Caffeine test on skinned muscle fibers from the biopsies showed normal response in both type 1 and 2 fibers. The present patients were diagnosed as having exertion-induced heat stroke, but with no increased muscle fiber sensitivity to caffeine, suggesting that the pathomechanism differs from that of malignant hyperthermia induced by malfunction of sarcoplasmic reticulum.

Fourier transform infrared analyses of some particulate drug mixtures using a diamond anvil cell with a beam condenser and an infrared microscope

Although the diamond anvil cell (DAC) has been used in many forensic science laboratories for the analysis of trace evidence, few applications of this technique for the analysis of controlled substances have been reported. This may be due to both an unfamiliarity on the part of forensic drug chemists with this accessory and the nature and quality of spectra that result from use of a DAC on a dispersive instrument. Along with low energy throughput, which results in relatively high noise levels, strong broad diamond absorptions occur. With the use of a Fourier transform infrared instrument, these do not present a problem and nanogram quantities of materials can be analyzed when the DAC is used with an infrared microscope. Since single crystals can be sampled with the DAC, simple physical separations (involving particle-picking) can be used in certain cases to isolate drugs from particulate mixtures for infrared analysis. This method is especially useful for some "difficult" mixtures and residues, and several examples of such analyses involving samples of forensic science interest are presented.

Ultrastructural and mechanical properties of electrically inexcitable skeletal muscle fibers of the crustacean Atya lanipes

Examination of the ultrastructure and mechanical activation of the ventro-abdominal flexor muscle of the freshwater crustacean Atya lanipes shows that the fibers are of the long sarcomere, tonic type. The fibers possess an ample and well-organized internal membrane system, with extensive regions of T/SR dyad contacts near the ends of the A bands. An orbit of 10-12 thin filaments surrounds each thick filament. The lanthanum tracer method reveals a highly regular organization of the T-system, Z-tubules, and multiple internal clefts. Tension generation responds to extracellular potassium in a concentration dependent manner and is very slow. Mechanical activation is strictly dependent on extracellular Ca2+, even though these muscle fibers do not generate Ca2+ currents when depolarized. Tension development responds to caffeine and is also dependent on extracellular Na+, suggesting that Ca2+ release from the SR and Ca2+ influx via the Na/Ca exchanger intervene in mechanical activation.

Prediction of malignant hyperthermia susceptibility in low-risk subjects. An epidemiologic investigation of caffeine halothane contracture responses. The North American Malignant Hyperthermia Registry

The most commonly used laboratory test for predicting malignant hyperthermia susceptibility is the caffeine halothane contracture test. However, the specificity and sensitivity of proposed North American diagnostic guidelines for this test have never been evaluated in a large, human study population. Therefore, the authors conducted a multiinstitutional, prospective study of skeletal muscle contracture responses in a subject population at low risk for malignant hyperthermia susceptibility to help determine the specificity of the proposed guidelines. Subjects were selected arbitrarily from a population of patients undergoing surgery unrelated to performance of a diagnostic muscle biopsy. Subjects were admitted to this study and were presumed nonsusceptible if there was no evidence of any of the following malignant hyperthermia risk factors: prior abnormal response to triggering anesthetic agents, myopathy, or family history of malignant hyperthermia susceptibility. The authors suggested rejection of the proposed diagnostic guidelines if an 85% specificity estimate among subjects could not be obtained. The authors analyzed the responses of 1,022 muscle fascicles, derived from 176 subjects, to the following: 1) separate administration of 3% halothane or incremental caffeine concentrations, or 2) the joint administration of 1% halothane and incremental caffeine concentrations. The following contracture results were obtained. First, for individual fascicles, 9.2% exceeded a greater than 0.7 g threshold for 3% halothane, 15.2% exceeded a greater than or equal to 0.2 g threshold for 2 mM caffeine, 32.4% exceeded a 1-g increase for less than 4 mM caffeine, 2.6% had a greater than 7% maximal increase in tension at 2 mM caffeine, and 63.5% had a "halothane caffeine-specific concentration" at less than or equal to 1 mM caffeine. Second, the percentages of subjects with 1 or more fascicles exceeding the proposed threshold were as follows: 45.8% for the four-component, 28.8% for the three-component, and 32.7% for the two-component contracture test. Third, the percentages of subjects with 1 or more fascicles exceeding the proposed threshold for both halothane and caffeine were as follows: 9.5% for 3% halothane and 2 mM caffeine, 2.0% for 3% halothane and 7% maximal increase in tension at 2 mM caffeine, and 11.0% for 1% halothane and 2 mM caffeine. Fourth, center-to-center differences were the major source of variation in the rate that subjects exceeded proposed thresholds. These data demonstrate that proposed diagnostic guidelines must be modified to improve specificity estimates before adoption by diagnostic centers.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence for related myopathies in exertional heat stroke and malignant hyperthermia

Malignant hyperthermia may be a human stress syndrome, of which heat stroke is one manifestation. Two men in military service who had episodes of exertional heat stroke, and their immediate family members, were tested for susceptibility to malignant hyperthermia by in-vitro contracture tests on skeletal muscle samples. Muscle from both patients had a normal response to caffeine but an abnormal response to halothane. Muscle from the father of one patient had an abnormal response to halothane, and that from the father of the second patient had an abnormal response to ryanodine. The results indicate that clinical heat stroke may be associated with an underlying inherited abnormality of skeletal muscle that is similar, but not identical, to that of malignant hyperthermia.

[A new emphasis on the diagnosis of malignant hyperthermia using the in vitro contracture test?]

In accordance with the protocol of the European Malignant Hyperpyrexia Group, an account is given of the experience regarding establishment of the "in vitro contracture test" for diagnosis and exclusion of malignant hyperpyrexia disposition at the University Clinic of Leipzig. Since its commencement in 1986 these diagnostic possibilities are being increasingly utilized, and--basing on 76 MH manifestations and suspected cases--324 persons have been examined until now. Besides the representation of the methodical features (e.g. performance of biopsy in tranquanalgesia in children), emphasis was on the safety of executing this test (attaining higher specificity, total absence of MH manifestations). The epidemiological study of the results shows the varying knowledge of physicians and the interference by insufficient investigation alternatives in individual areas. On the basis of the results, the use of the in vitro contracture test is recommended in all MH suspected cases by the authorized and qualified regional centres.

Spatial and temporal suppressive behavior of bitter-sweet mixtures

Bitter-sweet suppression in sucrose-caffeine mixtures was checked directly by measure of perceived intensity and total persistence time and indirectly by measure of the volume of water employed to remove each taste sensation.

[Diagnosis of malignant hyperthermia. The platelet test versus the in vitro contracture test]

An eight-year-old boy was scheduled for an orthopaedic operation with a clinically abortive reaction of malignant hyperthermia and a positive platelet test result. Since there has been no validation for this platelet test, we performed a muscle biopsy and the caffeine- halothane-contracture test (CHCT). The young patient was found to be negative (MHN) in CHCT. Furthermore, the valence and the validity of the used platelet test are discussed for diagnostic purposes. With regard to resulting consequences, first of all in respect of possibly false negative results, we suggest to investigate all patients classified by this platelet test with the accepted and established CHCT.

Anxiogenic effects of m-CPP in patients with panic disorder: comparison to caffeine's anxiogenic effects

The behavioral and neuroendocrine effects of meta-chlorophenylpiperazine (m-CPP), a serotonergic agonist, were compared with the effects of caffeine, an adenosine antagonist, in panic disorder patients. Patients with panic disorder were given single oral doses of 0.5 mg/kg m-CPP, 480 mg caffeine, and placebo on separate days under double-blind conditions. Both m-CPP and caffeine had significantly greater anxiogenic and panic-inducing effects than placebo, although caffeine produced nonsignificantly greater increases on all anxiety rating scales than m-CPP. Both m-CPP and caffeine produced significant equivalent increases in plasma cortisol concentrations, but only m-CPP produced plasma prolactin increases. These findings provide further evidence implicating both the serotonergic and adenosinergic receptor systems in the neurobiology of panic disorder.

Phenomenology and neurobiology of social phobia: comparison with panic disorder

Like panic disorder, social phobia is a common, frequently severe, anxiety disorder that can cause significant work and social impairment. Unlike panic disorder, social phobia has only recently begun to undergo neurobiologic study and to receive pharmacotherapeutic attention. There is a high comorbidity between social phobia and panic disorder; however, many differences exist--including age at onset, gender distribution, contextual framework of anxiety, help-seeking and help-avoidance behavior, quality of sleep and sleep patterns, caffeine and lactate sensitivity, and, most probably, pharmacologic responses. Social phobia can now be included among the growing number of anxiety disorders that respond to pharmacotherapy.

Organic dissociative syndrome associated with antimigraine pharmacotherapy

This report describes an acute organic brain syndrome with a fugue-like state in association with antimigraine pharmacotherapy. The differential diagnosis of: 1. possible psychotoxic effects of the combination of propranolol, imipramine, and butalbital; 2. confusional migraine with amnesia; and 3. psychogenic dissociation is considered. Although organically induced dissociative states are of clinical, neuropsychological and medico-legal significance, the DSM-III and DSM-III-R have specific categories only for dissociative conditions that are strictly psychogenic in origin.

Are there interactions and relations between genetic and environmental factors predisposing to high blood pressure?

An overview of published observations suggests that both genetic predisposition and environment work together to produce hypertension in most persons. High blood pressure before age 55 occurs 3.8 times more often among persons with a strong positive family history of high blood pressure. Much of the total variability in blood pressure in modern populations seems attributable to genetic factors. Estimates of the proportion of the variance attributable to all genetic factors (heritability [H2]) vary from 25% in pedigree studies to 65% in twin studies for sitting diastolic blood pressure. Several biochemical traits associated with high blood pressure are highly genetic (H2, 78-84%) and may help elucidate the pathophysiology of high blood pressure. While pertinent environmental factors such as salt intake, alcohol use, and amount of exercise also correlate significantly among relatives, only 7% of the total variance of diastolic blood pressure seems attributable to all shared environmental factors in family households. Thus most familial aggregation of high blood pressure appears to be due to genes rather than shared family environment. Practical benefit may result from identifying familial predisposition in multiple siblings with high blood pressure before age 55 and lipid abnormalities (labeled "familial dyslipidemic hypertension"). About 12% of high blood pressure patients have familial dyslipidemic hypertension and also have high risk of early coronary heart disease. Hyperinsulinemia and central obesity as well as high triglycerides and low high density lipoprotein cholesterol are prominent features of familial dyslipidemic hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

The caffeine contracture test for malignant hyperthermia: caffeine citrate, caffeine benzoate or caffeine free base?

The aim of the present study was to investigate whether the three different caffeine preparations--caffeine citrate, caffeine benzoate and the free base--used for in vitro diagnosis of malignant hyperthermia susceptibility--produced the same amount of contracture in rat diaphragm. At equimolar caffeine concentrations, the pure base generated more tension in the rat diaphragm muscle than caffeine benzoate or caffeine citrate. The citrate lowers the pH and the free Ca2+ concentration of the test bath and thus suppresses the caffeine contracture. The benzoate is believed to inhibit the caffeine contracture by its carbonyl group in a way similar to the effect of benzocaine.

Plasma immunoreactive endothelin-1 in experimental malignant hypertension

We measured plasma concentrations of immunoreactive endothelin-1 (irET-1) in the prehypertensive and hypertensive phases in spontaneously hypertensive rats (SHR) and in malignant hypertension caused by deoxycorticosterone acetate (DOCA)-salt administration in SHR. We also measured concentrations of this peptide in another model of malignant hypertension, the two-kidney, one clip (2K1C) renovascular hypertensive rats chronically given caffeine. Plasma irET-1 concentrations in young (6-week-old) and mature (18-week-old) SHR did not differ from those of age-matched Wistar-Kyoto (WKY) rats. Four weeks of treatment with DOCA-salt increased blood pressure, blood urea nitrogen, serum creatinine, and plasma irET-1 in SHR but not in WKY rats. Eight weeks of DOCA-salt treatment further increased these values in SHR. Plasma irET-1 concentrations were not increased in the 2K1C rats. Six weeks of caffeine administration increased blood pressure, blood urea nitrogen, serum creatinine, plasma renin activity, and plasma irET-1 in the 2K1C rats but not in the sham-operated rats. High-performance liquid chromatographic profiles of plasma extracts pooled from these rats with malignant hypertension showed that a major component of irET-1 eluted in the position of synthetic ET-1 (1-21). Furthermore, acute hypertension induced by angiotensin II or phenylephrine did not affect the plasma irET-1 concentration in rats. The results suggested that the plasma ET-1 concentration is increased in rat models of malignant hypertension and that the high blood pressure itself is not the main factor involved in the increase of plasma ET-1.

A comparison of the caffeine halothane muscle contracture test with the molecular genetic diagnosis of malignant hyperthermia

Malignant hyperthermia (MH) is currently diagnosed by the caffeine-halothane contracture (CHC) test. In a previous study, this test was used to establish linkage between the human gene for MH susceptibility and the ryanodine receptor (RYR) gene. The current study extends the genetic linkage analysis to a large French-Canadian kindred. In this family, genetic linkage between RYR and MH genes was not demonstrable using the currently recommended limits of normal for the CHC test in the identification of MH-susceptible individuals. With CHC test threshold limits below those currently recommended, however, complete linkage between the RYR and MH genes was seen. Comparisons of CHC test results with genetic linkage studies will increase the diagnostic accuracy of both tests as well as generate new insights into the biology of MH.

Pregnancy-induced changes in drug metabolism in epileptic women

The pharmacokinetics of antiepileptic drugs may be altered during pregnancy, resulting in decline of serum concentrations and subsequent suboptimal control of seizures. We investigated changes which may occur during pregnancy in hepatic drug handling by comparing metabolic ratios of 15 pregnant epileptic women to 15 nonpregnant epileptic women, as well as 10 pregnant nonepileptic and 10 nonpregnant nonepileptic controls. We used the caffeine test to describe several enzyme activities: P450 1A2, xanthine oxidase, n-acetyltransferase and hydroxylation. For this end, ratios were calculated among a number of metabolites of the main demethylation pathway of caffeine. In addition, we measured D-glucaric acid excretion for specific characterization of antiepileptic drug metabolism. Paired comparison of epileptic women in late pregnancy and six to eight weeks post partum revealed statistically significant decreases in P450 1A2, xanthine oxidase and n-acetyltransferase activities, and a significantly increased hydroxylation activity during pregnancy. Twenty-one of the 30 epileptic women (70%) were found to be fast acetylators, whereas the normal distribution in the nonepileptic control groups was 50%. Excretion of D-glucaric acid was significantly increased in all epileptic patient groups as compared to the matched nonepileptic control groups. Importantly, it was also significantly increased in the pregnant nonepileptic control group as compared to the nonpregnant nonepileptic women. Overall, our results suggest that enzymatic pathways involved in antiepileptic drug metabolism tend to be increased during pregnancy as a potential cause for observed lower serum concentrations of these drugs.

[Nutrition recommendations (1990)]

As of last year, new Canadian dietary recommendations and nutritional requirements have been established. The combination of these two documents evolved as a result of a better understanding of nutrition, as well as, an awareness that the problems related to nutritional deficiencies have resulted in numerous chronic diseases. This article, after an initial review of the origin of these documents, highlights the main changes that have occurred and reviews how this information is used and interpreted by various health care professionals.

Caffeine as a metabolic probe: exploration of the enzyme-inducing effect of cigarette smoking

It has been realized recently that the primary metabolism of caffeine in humans is catalyzed by P-450IA2 and that the rate of caffeine metabolism can be estimated from a metabolic ratio in a single urine sample. A population of 178 students including 19 smokers were subjected to this caffeine test to establish their P-450IA2 index. Both stated numbers of cigarettes smoked per day and urinary cotinine levels as a confirmatory measure correlated significantly with enzyme activity showing dose-effect relationships (r = 0.62 and 0.89, respectively). Nevertheless, more nonsmokers than smokers had the highest enzyme indexes, suggesting that dietary elements or other factors may determine P-450IA2 activities in populations. Because P-450IA2 is a monooxygenase that may be confined to the liver, caffeine reveals directly the Ah-receptor-dependent enzyme induction only in the liver, but it may also be a signal of induction elsewhere.

Alcohol and other dietary factors in relation to serum hormone concentrations in women at climacteric

The relationships between concentrations of endogenous hormones in serum and dietary intakes of alcohol, fats, fiber, and caffeine were examined in 325 healthy Massachusetts women aged 50-60 y who reported having a normal menstrual period within the previous 12 mo. Diet was assessed by a semiquantitative food frequency questionnaire. Hormones assayed were estrone, estradiol, percent free estradiol, sex-hormone-binding globulin (SHBG), cortisol, and gonadotropins. Alcohol intake was not associated with concentrations of estrogens or gonadotropins. Neither total fat intake nor the fat composition of the diet influenced hormone concentrations. Fiber intake was positively correlated with SHBG; no associations with estrogens were seen. Caffeine intake was inversely correlated with free estradiol and positively correlated with SHBG. These data suggest that fat, fiber, and alcohol intakes of US women at climacteric are not determinants of variations in estrone and either total or percent free estradiol.

Drug policy: striking the right balance

Drug policy should strike the right balance between reducing the harm done by psychoactive drugs and reducing the harm that results from strict legal prohibitions and their enforcement. It is concluded, from a cost-benefit analysis based on pharmacologic, toxicologic, sociologic, and historical facts, that radical steps to repeal the prohibitions on presently illicit drugs would be likely, on balance, to make matters worse rather than better. Specific recommendations are offered for ameliorating the dangers to users and to society that are posed by each addictive drug.