Plasma cortisol levels in pigs susceptible and resistant to malignant hyperthermia

Plasma cortisol levels were measured in Landrace pigs susceptible to malignant hyperthermia (MH), Landrace pigs resistant to MH and in Largewhite pigs, during growth halothane anaesthesia and after injections of Synachten. From 3 to 6 months of age mean cortisol levels in susceptible Landrace were 193,2 +/- 49,7 nmol/l, in resistant Landrace 220,8 +/- 24,8 nmol/l and in Largewhite 278,8 +/- 13,8 nmol/l. These values were not significantly different. After injection of 1 mg Synachten intravenously, plasma cortisol levels did not increase significantly in susceptible pigs. In resistant landrace pigs and Largewhite pigs the plasma levels after injection were significantly greater than pre-injection levels (P less than 0,05) and significantly different from susceptible Landrace levels. During halothane anaesthesia, cortisol levels rose more in resistant pigs than in susceptible pigs, but differences were no significant. These results suggest that susceptible pigs have a decreased ability to secrete cortisol during stress.

Influence of pH, temperature, halothane and its metabolites on osmotic fragility of erythrocytes of malignant hyperthermia-susceptible and resistant pigs

Erythrocyte fragility of malignant hyperthermia-susceptible and resistant pigs has been examined as a function of pH and temperature in the absence and presence of halothane and its metabolites. A decrease in pH from 7.40 to 6.95 increased the fragility of both susceptible and resistant pigs, but the increase in susceptible animals was significantly greater than that in resistant animals. An increase in temperature led to a reduction of erythrocyte fragility of both types of pig. The most consistent differences in haemolysis between susceptible and resistant pigs occurred at sodium chloride concentrations of 0.120 and 0.137 mol litre-1. At all pH values examined and at 39 and 41 degrees C, but not at 43 degrees C, erythrocytes from susceptible pigs showed greater haemolysis in sodium chloride 0.120 and 0.137 mol litre-1 than did erythrocytes from resistant pigs. Halothane or its metabolites, at concentrations occurring during anaesthesia, did not alter erythrocyte fragility.

Plasmodium falciparum strains from Papua New Guinea: culture characteristics and drug sensitivity

Seven strains of Plasmodium falciparum from Papua New Guinea have been established in continuous in vitro culture. Samples with a high initial parasitaemia were more likely to form continuous lines, possibly due to the time required for transport of infected blood samples from Papua New Guinea to laboratories in Australia. Most but not all established lines were resistant to chloroquine and all were resistant to pyrimethamine, possibly reflecting the parasite strain characteristics in that region.

Cholinergic regulation of intracerebral noradrenergic pathway-induced hypothalamic vasodilatation

Stimulation of the intracerebral noadrenergic pathway (INP) increases hypothalamic blood flow as measured in conscious rabbits using a 133xenon washout technique. This increase is abolished by the intra-hypothalamic injection of 0.65 micrograms of the muscarinic antagonist atropine and by 5 micrograms of the nicotinic antagonist mecamylamine. Further, 1 micrograms of the cholinomimetic methacholine produces a similar vasodilation. While methacholine enhances the vasodilatation on stimulation of the INP, destruction of the pathway abolishes the entire vasodilator response to methacloline. Removal of the superior cervical sympathetic ganglia does not abolish vasodilatation. A role for endogenous acetylcholine in the INP-induced vasodilatation is thus proposed. This vasodilatation appears to act via an increase in neuronal activity with a resultant lowering of local pH, as 60 micrograms barbiturate and intra-hypothalamic bicarbonate abolish the dilatation completely. The cholinergic vasodilatation reported here is probably an excitatory effect on the INP and is not likely to be due to an inhibition of sympathetic vasoconstrictor tone.

A halothane-induced biochemical defect in muscle of normal and malignant hyperthermia-susceptible Landrace pigs

Muscle adenosine triphosphate (ATP), glucose-6-phosphate, phosphocreatine, and pH were measured in nine malignant hyperthermia (MH)-susceptible and 14 MH-resistant Landrace pigs. Muscle biopsies were taken before (under barbiturate anesthesia) and after exposure to halothane. When compared to levels during barbiturate anesthesia, exposure to halothane had no immediate effect on muscle ATP levels in either MH-susceptible or -resistant pigs. However, once malignant hyperthermia developed in susceptibe pigs ATP levels decreased significantly. In both susceptible and resistant pigs halothane increased muscle glucose-6-phosphate and decreased muscle phosphocreatine and pH significantly below control levels observed during barbiturate anesthesia. In susceptible pigs these changes were significantly more marked than were the changes produced in resistant pigs. These data indicate that the effect of halothane on muscle metabolism is similar in both MH-resistant and -susceptible pigs. The results suggest that the effect of halothane is to inhibit aerobic metabolism by preventing mitochondrial dehydrogenation of pyruvate. Inhibition is complete in susceptible pigs but only retarded in resistant pigs. In susceptible pigs the consequent lactacidosis, hyperthermia, and reduction in ATP synthesis contribute to the development and maintenance of rigidity.

Effects of temperature, adenosine triphosphate and magnesium concentrations on the contraction of actomyosin isolated from halothane-sensitive and -insensitive German Landrace pigs

The effects of temperature, adenosine triphosphate and magnesium on the calcium sensitivity of actomyosin were investigated on actomyosin obtained from six halothane-sensitive and five halothane-resistant German Landrace pigs. No difference in the contractile properties was found in actomyosin from the two types of pig. However, in both types calcium sensitivity of the actomyosin was lost at temperatures slightly greater than those occurring physiologically. Both ATP and Mg2+ protect against the loss of calcium sensitivity. These results suggest that the basic lesion in halothane-induced malignant hyperthermia does not lie in the contractile proteins. It is likely, however, that the decreases in intracellular ATP and Mg2+ concentrations which occur in pigs during malignant hyperthermia, contribute to the development of the syndrome.

Substance P increases hypothalamic blood flow via an indirect adrenergic-cholinergic interaction

1 Hypothalamic blood flow (HBF) was measured in conscious rabbits by the 133xenon washout technique. 2 Substance P in a dose of 50 or 500 ng increases HBF while 5 ng is without effect. 3 Cholinoceptor blockade, with either atropine or mecamylamine abolishes the vasodilator effect of substance P. 4 Chemical sympathectomy of the hypothalamus with 6-hydroxydopamine, or adrenoceptor blockade with either propranolol or phenoxybenzamine abolishes the effect of substance P on HBF. 5 Destruction of the intracerebral noradrenergic pathway (INP), or blockade of its vasodilator action, with barbiturate or bicarbonate, likewise prevent the vasodilator action of substance P. 6 These results suggest that substance P may cause an increase in HBF via the release of endogenous acetylcholine, which in turn stimulates the INP.

Clinical studies of the use of a fluorogenic substrate assay method for the determination of plasminogen

Utilization of a recently reported method for the determination of plasminogen by fluorometric technique (Ref. 3, Pochron, et. al., Thrombosis Research, Vol. 13, pg. 733, 1978) was compared with acceptable methodologies (e.g. the caseinolytic and radial–immunodiffusion assays). Excellent results were seen with the normal range of 2.4–3.8 CTA U/ml of plasminogen by the synthetic substrate assay as compared to 8.7–14.3 mg/dl by the radialimmunodiffusion assay. Normal ranges for the caseinolvtic assay were seen to be 2.2–4.0 CTA U/ml. Patients’ studies were performed on a general medical population but centered primarily on “pre” and “post” operative coronary-pulmonary bypass patients. In all cases studied, a drop in Plasminogen level was noted in this group of patients following surgery (20-50%). Other clinical data will be presented indicating that the determination of plasminogen by the fluorometric assay procedure is sensitive and accurate for clinical situations.

Evidence for an indirect cholinergic regulation of blood flow in the hypothalamus of conscious rabbits

1 The effects of methacholine, atropine and adrenoceptor blockade on hypothalamic blood flow (HBF) were measured in conscious rabbits. 2 A dose of 1 microgram methacholine increased HBF while smaller and larger doses had no significant effect. 3 The vasodilatation induced by methacholine was blocked by atropine and by chemical sympathectomy of the hypothalamus with 6-hydroxydopamine. 4 The vasodilatation was reversed by propranolol but was not affected by phenoxybenzamine. 5 These results suggest that the vasodilator action of muscarinic receptor agonists on hypothalamic resistance vessels depends upon the integrity of a noradrenergic system, and is mediated via beta-adrenoceptors.

Strain differences in the immune response of mice to homologous sperm-specific lactate dehydrogenase (LDH-C4)

The sperm-specific isozyme of murine lactate dehydrogenase (LDH-C4) was injected into female mice of various strains. Two regulatory phenotypes characterize the resultant immunity to LDH-C4: one is manifested by high, intermediate or low levels of response, the other by the immediate or delayed maturation of peak titer. The response of several strains can be classified as high (SWR, SJL, BABL/c, C3H/He) and intermediate to low (A, CBA, DBA/2, DBA/1, C57BL/6) according to the level of antibody production and cell mediated immunity. BALB/c, SJL and SWR strains are immediate responders while DBA/2 and C3H/He mice are clearly delayed responders. Maturation and magnitude of response do not appear to be related. Both the antibody and cell mediated responses are T-dependent, but are not obviously associated with Ig allotype or H-2 regulation.

Fluorescence polarization: measurements with a photon-counting photometer

A T-format, photon-counting polarization photometer was constructed to facilitate precise polarization measurements at low signal-to-noise ratios. The instrument optics and electronics are described. Several examples of the instrument's performance are given, including measurements on picomolar fluorescein solutions at low excitation resolution and the excitation polarization spectrum of indole (2 x 10(-4)M) at a resolution of 5 A.

Vasodilator mechanism of the intracerebral (non-sympathetic) adrenergic pathway

Stimulation of the intracerebral noradrenergic pathway causes a vasodilatation in the hypothalamus. We have investigated whether this vasodilatation is caused by a direct vascular innervation or whether it is secondary to an activation of hypothalamic neurons. Non-specific neuronal activation using glutamate increased the mean hypothalamic blood flow. Depression of neuronal activity using barbiturate reduced hypothalamic blood flow and blocked the glutamate and the intracerebral noradrenergic pathway-induced vasodilatation. These results suggest that stimulation of the intracerebral noradrenergic pathway increases hypothalamic neuronal activity which indirectly causes a vasodilatation.

Sucrose-negative variants of Candida tropicalis

Four cultures of a Candida sp. that lacked alpha-glucosidase activity were isolated from clinical specimens. Physiological, morphological, and serological characterizations of the yeasts and deoxyribonucleic acid reassociation studies supported their classification as a variant of C. tropicalis.

Measurement of lead content of children's teeth in situ by x-ray fluorescence

The central nervous system of young children is particularly sensitive to neurological damage due to excessive lead exposure. The lead stored in a tooth is permanent and related to the quantity of ingested lead. The lead is assayed by measuring the characterisitc radiation from lead in a tooth in situ irradiated with gamma rays from a cobalt-57 source. The sensitivity of the method is adequate to measure lead levels commonly associated with environmental background. The X-ray exposure to the tooth necessary for this determination is approximately one tenth of that required for a routine dental examination.

Antenatal diagnosis of neural tube defects

One hundred women with pregnancies at risk for the recurrence of neural tube defects have entered our monitoring programme of echography and alphafetoprotein estimation (AFP) on amniotic fluid and maternal serum during the second trimester. The results of these pregnancies, the application of the programme, sources of error, and the reliability of alphafetoprotein levels are discussed. Conclusions regarding the value of the tests and routine antenatal screening are made.

Effects of sleep of restricted sleep. A cat case study

One male cat was adapted to different schedules of restricted sleep. The cat was allowed to go to sleep during a certain number of hours per day. During the rest of the 24 h period, wakefulness was enforced by means of a treadmill. The following schedules of restricted sleep were run: 12 h sleep--12 h treadmill (12S--12T), 8S--16T, 4S--20T. The cat was also adapted to a 36 h day: 12S--24T. The sleep was investigated after at least 2 weeks on each schedule and compared to ad lib. sleep (24S--0T). As available sleep time bacame shorter, the composition of the sleep changed. LSWS (in % of available sleep time) decreased, while DSWS % and REM sleep % increased. The length of the DSWS and REM sleep episodes increased with decreasing sleep time, as did sleep cycle length.

Evidence for a dual innervation affecting local blood flow in the hypothalamus of the conscious rabbit

We have attempted to evaluate the role of adrenergic nerves which arise from the superior cervical ganglia or which are intracerebral throughout their course, in the control of local cerebral blood flow (CBF). Hypothalamic blood flow (HBF) was measured in the conscious rabbit by the 133Xe-clearance technique. Stimulation of the upper brainstem, using 5-Hz, 3-V, 1-msec, square wave pulses, increased by HBF by a mean of 7.6 ml/100 g per min (P less than 0.005). This effect was abolished by the intrahypothalamic injection of the beta-adrenoreceptor blocker, propranolol, and by chemical sympathectomy of the hypothalamus or of the upper brainstem with 6-hydroxydopamine, but was not altered by bilateral cervical ganglionectomy. Intrahypothalamic injection of 0.1 mug of tyramine caused a mean decrease in HBF of 15.6 ml/100 g per min (P less than 0.001). This effect of intrahypothalamic injection of tyramine was abolished by bilateral cervical sympathectomy but not by chemical sympathectomy of the upper brainstem. These results support the idea that local CBF, at least in the hypothalamus, is mediated by two distinct pathways. The first consists of the sympathetic nerves which arise in the cervical ganglia, and which activate intrahypothalamic alpha-receptors to cause constriction. The second is an entirely intracerebral noradrenergic pathway which stimulates beta-receptors to cause vasodilation.

A survey of female patients in Carstairs State Hospital

The characteristics of the female population in Carstairs State Hospital are described. The patients were predominantly young, single and physically fit, with a history of significantly more previous psychiatric admissions than their male counterparts. Thwy showed a greater degree of violence towards both themselves and others before their admission to Carstairs; and their length of stay was much shorter. One third of the patients have an IQ of less than 70.

A fifteen-year review of female admissions to Carstairs State Hospital

A survey was made of all female admissions to the State Hospital, Carstairs, between the time of the first female admission in 1959, and 31 December 1973. There were 66 female admissions, constituting 7-1 per cent of the total admissions over the same period. The females fall into two separate sub-groups. The first consists of persistently violent patients transferred from other hospitals, suffering from mental subnormality or personality disorder; they have a poorer prognosis than the second group, who are sent from Courts or prison because of single serious acts of violence often directed at a member of the family, and who suffer from a personality disorder or from schizophrenia. Some features of the two groups are compared and contrasted. There may be an increase in the proportion of pateints in the first group being admitted to the State Hospital, and some implications of this trend are discussed.

Sporotrichoid Nocardia brasiliensis infection. Response to potassium iodide

A lymphocutaneous infection due to Nocardia brasiliensis occurred in a Maryland gardener. This infection responded rapidly and completely to potassium iodide therapy.

The lead content of teeth. Evidence establishing new minimal levels of exposure in a living preindustrialized human population

Teeth were collected from populations differing in their degree of industrialization and from prehistoric populations. Lead analysis of dentine revealed that in contemporary teeth the lead level was related to the degree of industrialization and that in prehistoric teeth very low concentrations of lead were present. Because tooth lead reflects the body burden of lead, this result suggested that the prehistoric populations and modern nonindustrial populations were exposed to environments low in lead. Teeth from a contemporary population of nonindustrialized Indians of the Lacandon forest in Mexico contain lead in concentrations comparable with those of the prehistoric populations. Comparison of the Indian teeth with teeth from a modern industrial population reveals a 45-fold difference in median tooth lead level. This finding lends support to the hypothesis that high levels of urban lead pollution result in elevated body burdens of lead.

Blood-lead levels of monkeys treated with a lead-containing (N2) root canal cement: a preliminary report

The effect of a root canal filling material on the level of lead in blood of rhesus monkeys was examined by anodic stripping voltometry. Blood-lead levels after root canal treatment with N2 cement were elevated when compared to preoperative controls. Lead 210 was incorporated into the leadfree N2 cement to identify the source of lead. Analyses of blood samples for 210Pb indicated that the lead originated from the filling material.

On the toxicity of procaine for pigs

Procaine caused respiratory arrest in halothane-anaesthetized normal Landrace pigs at a dose of 4,2 - 8,2 mg/kg. In some cases death due to respiratory failure occurred after giving 10 - 13 mg/kg. Because of its toxicity in pigs procaine is unsuitable for treating the porcine malignant hyperthermia syndrome.

Physiological and DNA characterization of Candida maltosa, a hydrocarbon-utilizing yeast

Selected yeast classified as Candida sake van Uden et Buckley were examined for their physiological, morphological and immunological properties and their DNA relatedness. Candida maltosa Komagata, Nakase et Katsuya is herein recognized as a species separate from C. sake, Candida maltosa was distinguished from C. sake and from C. tropicalis by insignificant DNA reassociation. In addition, C. maltosa was distinguished from C. sake by its higher maximal growth temperature and lower guanine plus cytosine content of its DNA and from C. tropicalis by its failure to utilize soluble starch for growth and its resistance to cycloheximide. The species C. cloacae and C. subtropicalis are placed in synonymy with C. maltosa.

Diagnostic value of serum creatine phosphokinase activity for the porcine malignant hyperthermia syndrome

Serum creatine phosphokinase (CPK) activity was measured in 10 German Landrace pigs from 11 to 28 weeks of age. A pronounced age dependence of serum enzyme activity was observed, peak activity occurring at 19 weeks of age. At the end of the growth period, when the pigs were challenged with halothane to detect the malignant hyperthermia syndrome, 3 pigs were found to be susceptible. Singificant increases in the serum enzyme levels in the susceptible pigs were observed only at 11 and 28 weeks of age. Serum enzyme levels measured during the rapid phase of growth could not be used to predict the malignant hyperthermia syndrome. Elevated serum CPK levels were also observed in two litters of Large White and Landrace x Large White pigs, breeds known to be stress-resistant. No pigs in these litters were susceptible to halothane, even though CPK levels were similar to those of the German Landrace pigs. The results indicate that serum CPK levels can be used as evidence of predisposition to the malignant hyperthermia syndrome but cannot be relied on as a single ultimate test.

Procaine in porcine malignant hyperthermia

Serum creatine phosphokinase, rectal temperature and muscle pH at death were measured in three halothane-susceptible Landrace pigs. Two of the pigs were treated with procaine. Although the course of the syndrome was different in the treated pigs, procaine did not reverse the established malignant hyperthermia syndrome.

Factors affecting serum creatine phosphokinase activity in pigs

Serum creatine phosphokinase activity was determined in German Landrace and Landrace x Large White pigs from 11 weeks to 28 weeks of age. A very pronounced age dependence of enzyme activity was observed in both groups, peak activities occurring at 19 weeks of age for the German Landrace and at 15 weeks for the crosses. The large increase in serum creatine phosphokinase activity observed occurred during the rapid phase of growth after which enzyme levels returned close to initial values. Sedatives and the stress of handling while obtaining blood can also cause raised serum creatine phosphokinase levels and complicate the interpretation of the data in regard to the detection of the stress syndrome. Enzyme activity also displayed a diurnal variation thus introducing a further parameter in the use of creatine phosphokinase activity for detection of the stress syndrome. Certain limitations in the method of measurement of creatine phosphokinase are discussed.

Adrenoceptors in intracerebral resistance vessels

1. The effects of tyramine and isoprenaline on hypothalamic blood flow (HBF) were measured in conscious rabbits. 2. Injections of small doses of tyramine caused an increase in HBF while larger doses caused a decrease in HBF. 3. Isoprenaline injections also produced an increase in HBF. 4. The vasodilatation induced by isoprenaline and the small dose of tyramine was blocked by propranolol. 5. The vasoconstriction induced by the larger doses of tyramine was abolished by phenoxybenzamine. 6. Chemical sympathectomy of the hypothalamus with 6-hydroxydopamine and depletion of biogenic amines by reserpine also abolished tyramine-induced vasocoonstriction. 7. These results suggest the presence of alpha- and beta-adrenoceptors in cerebral resistance vessels, and that these receptors may be activated by released (endogenous) noradrenaline.