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Biomedical subjects

D Lister

Publications and source records attributed to D Lister.

At least 19 recordsLinked to original sources
PubMed1978

Porcine malignant hyperthermia. VI: the effects of bilateral adrenalectomy and pretreatment with bretylium on the halothane-induced response.

The effects of bilateral adrenalectomy, together with the i.v. administration of bretylium tosylate 20 mg kg-1 on halothane-induced malignant hyperthermia (MH), were investigated in six Pietrain pigs. All six animals survived the halothane challenge, and failed to show any signs of increased muscle metabolism. Bilateral adrenalectomy alone prevented halothane-induced MH in three out of four Pietrain pigs, whereas the i.v. administration of bretylium alone protected only one pig out of an additional four animals studied. The results show that complete adrenergic blockade inhibits the susceptibility of Pietrain skeletal muscle to halothane and that the adrenal medulla makes an important contribution to this response.

Adrenalectomy↗
PubMed1977

Anaesthesia of pigs sensitive to malignant hyperthermia.

During general anaesthesia some pigs develop a hyperthermic response which is often fatal. The syndrome is most common in pigs which are susceptible to stress and have a low proportion of body fat. On the basis of an experimental investigation in Pietrain pigs recommendations are presented for the clinical management and treatment of susceptible animals.

Anesthesia↗
PubMed1977

Fat mobilization in Pietrain and Large White pigs.

I. Two experiments were done with Pietrain and Large White pigs (about 50 kg body-weight) to determine whether fat mobilization is enhanced in the stress-sensitive Pietrains (which also produce pale, soft, exudative (PSE) meat). 2. In Expt I, plasma glucose and insulin concentrations and free fatty acid (FFA) concentrations and composition were measured in five Pietrains and five Large Whites after feeding, during an infusion of norepinephrine (2.5 microng/kg body-weight per min), 16 and 21 h after the withdrawal of food and following insulin administration (0.3 IU/kg body-weight). The entry rate of oleic acid was measured 4 h after feeding. Body composition and longissimus dorsi pH measurements were made on killing the pigs 4 d after the experiment. 3. After feeding, the Pietrans tended to have lower concentrations of glucose and insulin in plasma compared with the Large Whites, and higher concentrations of FFA. The Pietrans also had a faster entry rate of oleic acid into body tissues. In fasting (16 h) these differences in hormone and metabolite concentrations were also present and relationships between them and body development could be detected. Pietrains had higher concentrations of FFA and lower concentrations of insulin than Large Whites at a particular stage of the development of fat and muscle (subcutaneous fat weight divided by longissimus muscle weight). 4. The fatty acid composition of FFA resembled that of the backfat triglycerides in fasting and during norepinephrine infusion but not in the fed state. In particular the proportion of fatty acid 18:I was low in the fed pigs and that of 18:2 was high. The contrast in FFA composition between the fed and stimulated state was greater in the Large Whites. 5. The Pietrains were less sensitive to the antilipolytic action of insulin. Glucose and FFA concentrations were similar in both breeds during the norepinephrine infusion although insulin concentrations were increased to a larger extent in Large Whites at the termination of the infusion. 6. In Expt 2, anaesthetized Pietrain and Large White pigs were given constant infusions of norepinephrine alone (2.5 microng/kg body-weight per min) and norepinephrine + propranolol (2, 10 and 20 microng/kg body-weight per min) or phentolamine (2 and 10 microng/kg body-weight per min). The aim was to determine whether the breeds differed in their sensitivity to norepinephrine when conscious responses to the hormone were prevented. 7. When norepinephrine alone was infused, fat mobilization was greater in the Pietrain pigs and glucose concentrations were greater in the Large Whites. Propranolol markedly reduced the lipolytic action of norepinephrine, particularly in the Pietrain pigs studied, and phentolamine reduced its glycogenolytic action, particularly in the Large White pig. 8...

Animals↗
PubMed1977

Porcine malignant hyperthermia. V: Fatal hyperthermia in the Pietrain pig, associated with the infusion of alpha-adrenergic agonists.

The effects of the administration of noradrenaline alone, and noradrenaline with either phentolamine or propranolol, on thermogenesis and substrate mobilization were investigated in six Pietrain (MH-susceptible) and six Large White (unsusceptible) pigs. The infusion of noradrenaline alone produced a significantly increased lipolytic response and a significantly decreased hyperglycaemic response in Pietrain pigs compared with the Large White breed. Although noradrenaline alone produced only a small increase in body temperature in both breeds, the administration of noradrenaline with propranolol in two Pietrain pigs was associated with the development of fatal hyperthermia. In a further experiment, phenylephrine or isoprenaline was infused into six Pietrain pigs. Three pigs, receiving phenylephrine, became hyperthermic and died, whereas isoprenaline had no effect on body temperature. The results demonstrate the importance of alpha-adrenergic stimulation to heat production in MH-susceptible pigs.

Adrenergic alpha-Agonists↗
PubMed1977

Two-site assay of bovine parathyroid hormone.

A two-site assay has been developed for bovine PTH. This technique involves reaction of the antigen with two antibody molecules with the purpose of increasing specificity. In paratice the hormone was extracted form plasma samples on to plastic tubes coated with antibody specific for PTH (1-34). Uptake was then measured using 125I-labelled antibodies specific for PTH (53-84). In this way a sensitive assay was obtained for PTH (1-84) which did not recognize molecular fragments. This technique was used in conjunction with immunoradiometric assays specific for either NH2-terminal (1-34) or CO2H-terminal (53-84) molecular fragments to study the clearance of infused PTH in the cow. Preliminary results support the hypothesis that the intact molecule is rapidly degraded in the peripheral circulation with the preferential disappearance of an NH2-terminal fragment. Studies on endogenous secretion during calcium and EDTA infusions indicated that there was little intact hormone present at the times when CO2H-terminal immunoreactivity was readily measured.

Animals↗
PubMed1976

Porcine malignant hyperthemia IV: Neuromuscular blockade.

The effect of tubocurarine and pancuronium on the initiation or prevention of porcine malignant hyperthermia (MH) was investigated in Pietrain pigs. Tubocurarine 0.6 mg/kg body weight inhibited a suxamethonium-induced response in three pigs, but failed to prevent a fatal halothane-induced response in a further four pigs. Pancuronium 0.2 mg/kg body weight was given to six pigs before a halothane challenge. Three animals developed MH and died; the remainder succembed only after reversal of the neuromuscular blockade. The partial protection afforded by large doses of pancuronium is discussed in relation to the ability of previous muscle activity to influence the sensitivity to halothane.

Animals↗
PubMed1976

Porcine malignant hyperthermia. I: Metabolic and physiological changes.

Porcine malignant hyperthermia was studied in seven Pietrain pigs under standardized experimental conditions. In five animals malignant hyperthermia was triggered with suxamethonium and halothane, but in two pigs suxamethonium alone was used. Characteristic metabolic and physiological changes were found and these are discussed with regard to a possible mechanism to explain the malignant nature of the syndrome.

Animals↗
PubMed1976

Porcine malignant hyperthermia. II: Heat production.

The contributions of aerobic and anaerobic muscle metabolism to the heat produced in porcine malignant hyperthermia were studied in seven Pietrain pigs. Oxygen consumption measurements were used to calculate the increase in muscle temperature as a result of aerobic metabolism and this was compared with the observed muscle temperature. The results show that in the initial stage of porcine malignant hyperthermia heat production is largely aerobic in origin. Terminally, aerobic metabolism can account for about half the observed temperature increase.

Animals↗
PubMed1976

Malignant hyperthermia in Belgian Landrace pigs rested or exercised before exposure to halothane.

Thirteen of 31 Belgian Landrace pigs developed malignant hyperthermia (MH) after breathing halothane. A short period of exercise 1 h before the administration of the triggering agent increased the incidence of the syndrome to 100% in eight similar pigs. Clinical symptoms were more marked and developed more rapidly in the exercised pigs. All the reacting pigs became typically acidotic, developed rigor and died. Serum Na+, K+, Ca2+, c.p.k., l.d.h. and protein concentrations were increased to a variable extent during the reaction and there was an increase in p.c.v. also. No hyperglycaemia was detected in pigs which were rested before receiving halothane. Four of the eight exercised pigs became markedly hyperglycaemic and plasma noradrenaline increased to higher values. Phosphocreatine and ATP decreased to low values and lactate increased in the muscles of all pigs which reacted. At the time of death, muscle glycogen had decreased significantly in the rested, but not in the exercised, MH pigs.

Animals↗
PubMed1976

Porcine malignant hyperthermia. III: Adrenergic blockade.

The effects of the establishment of an adrenergic blockade on suxamethonium-induced porcine malignant hyperthermia (MH) were investigated in Pietrain pigs. Six animals were fed reserpine 10 mg daily for 7 days and then challenged with suxamethonium. Three survived but the remainder developed fatal MH. In a further study of 10 pigs, either phentolamine 40 mug/kg/min or propranolol 50 mug/kg/min were administered for 30 min before suxamethonium stimulation and continued for the duration of the experiment. The five year beta-blocked pigs all became hyperthermic and died whereas the phentolamine-treated group survived. However, both alpha adrenergic blockade and successful reserpinization failed to prevent the abnormal muscle response to the first dose of suxamethonium.

Adrenergic alpha-Antagonists↗
PubMed1976

Breed differences in the position of the urethral meatus of gilts.

In a strain of Pietrain the distance between the vulva and the urethral meatus is greater than that of other breeds of pig. This difference is such that it is difficult to catheterise the bladders of Pietrain gilts since the available specula are either too short in length or too wide in diameter.

Animals↗