Myophosphorylase deficiency (glycogen storage disease Type V) in a herd of Charolais cattle in New Zealand: confirmation by PCR-RFLP testing

AIM

To describe a disease of muscle in Charolais calves and confirm the putative diagnosis of inherited myophosphorylase deficiency.

METHODS

Variously stained paraffin sections of muscle prepared from affected calves were used to describe the lesions. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) test was developed and applied to affected calves, their sires, dams and other individuals.

RESULTS

The lesions were those of rhabdomyolysis of skeletal muscles and sub-sarcolemmal spaces in normal fibres. The PCRRFLP test confirmed the expected mutation for phosphorylase deficiency of Charolais cattle in two affected calves. In addition, sires, dams and other closely-related individuals of four affected calves tested as heterozygous for the mutation. Other apparently unrelated animals also tested as heterozygous.

CONCLUSIONS

The diagnosis of myophosphorylase deficiency was confirmed. The PCR-RFLP test is suitable for use in controlling this recessively-inherited disorder as it can diagnose heterozygous individuals that are otherwise clinically normal.

Evaluation of a non-rebreathing circuit for small animal anaesthesia

Several new multi-purpose non-rebreathing anaesthetic systems have been developed for human anaesthesia. This study evaluated a New Zealand designed non-rebreathing circuit, the Palmerston Valve, in anaesthetised spontaneously breathing dogs and compared it to the widely used Lack coaxial circuit. Arterial blood gas measurements 60 minutes after induction demonstrated comparable slight increases in PaCO2 in nearly all dogs maintained on the Palmerston Valve and Lack coaxial circuit with halothane and oxygen mixtures, and a fresh gas flow rate of 70 ml/kg/min. Results suggest the Palmerston Valve is at least as efficient as the Lack coaxial circuit, while offering in the same unit the potential for economical controlled ventilation.

True exfoliation of the lens capsule. A clinicopathological report

A case of true senile exfoliation of the lens capsule is reported. Electron microscopic examination of the capsule confirmed capsular delamination. The proteins in the remaining sample of exfoliated capsule and in normal capsules were analysed by polyacrylamide gel electrophoresis in the presence of the dissociating agent, sodium dodecyl sulphate, and under reducing conditions (SDS--PAGE). Densitometric scans of electrophoretograms indicated the virtual absence of a 58 kilodalton (kDa) component and approximately half the level of a 74 kDa component in the exfoliated capsule relative to normal capsule. The remaining protein components detected were of identical molecular weight and abundance compared with the normal lens capsule.

Plasma concentrations of LH, prolactin, oestradiol-17 beta and progesterone in sows weaned after lactation for 10 or 35 days

Piglets were weaned from multiparous sows at 10 days (Group E; N = 7) or 35 days (Group C; N = 8) of lactation. Blood samples were collected at 8 h intervals from the day before weaning (Day--1) until and including the day of first mating, then once daily until 10 days post coitum. Additionally, 5 sows in each group were sampled at 30 min intervals for 12 h on Days--1, 0 and 1, then at 30 min intervals for 6 h daily until mating, finally at 30 min intervals for 2 h daily until 5 days post coitum. Group E sows had relatively longer weaning to remating intervals (8.3 +/- 0.8 compared with 5.0 +/- 0.7 days; P less than 0.01) and tended, but not significantly, to produce smaller subsequent litters (10.2 +/- 1.9 compared with 12.0 +/- 0.6). Sows in group E had lower lactational and post-weaning plasma LH levels (P less than 0.001). They also had greatly attenuated preovulatory LH rises and the area under the peak was reduced (P less than 0.01 and P less than 0.001, respectively). Preweaning plasma prolactin levels were higher at 9 days of lactation than at 34 days and levels in both groups dropped precipitously subsequent to piglet removal. Although peak levels of prolactin at oestrus did not differ between treatments, they tended to occur before the LH peak in sows of Group C and after the LH peak in Group E.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for malignant hyperthermia susceptibility

In vitro pharmacological testing of isolated muscle strips surgically removed under general anaesthesia from 10 members of a known MH family enabled identification of three MH positive individuals. Diagnosis of MH susceptibility was based on increased sensitivity to low concentrations of caffeine and the presence of halothane-induced contractures in MH susceptible muscle. Dantrolene sodium 15 mg/l completely prevented halothane-induced contractures in two muscle strips from one of the MH positive cases. The successful anaesthetic management of known MH patients is described, as is the successful management of a hyperthermic episode during recovery in one of the MH positive cases.

Porcine malignant hyperthermia: effect of dantrolene sodium on in-vitro halothane-induced contraction of susceptible muscle

Halothane-induced contractures in isolated muscle fibers from swine susceptible to malignant hyperthermia (MHS) were significantly less when fibers were incubated in KRB plus 6.2 x 10(-6) M dantrolene sodium prior to the administration of 4 per cent halothane. Administration of dantrolene sodium at the time of maximum contraction to NHS fibers in which contractures had been induced by halothane significantly increased the rate of relaxation of these fibers compared with similar fibers not treated with dantrolene sodium. This study indicates possible prophylactic and therapeutic value of dantrolene sodium in malignant hyperthermia and suggests that the previously reported effectiveness of dantrolene sodium in preventing and treating halothane-induced contractures may be due, at least in part, to its direct effect on muscles.