An acute case of Pimelea elongata toxicity in cattle in western New South Wales

In May 2019, 96 cattle died from Pimelea toxicity in a period of 19 days after potential exposure, with the first deaths occurring within 5 days. After examining the circumstances, we suspect that several factors contributed to the deaths. These included that recently purchased stock and transported had access to flooded land containing Pimelea elongata. This weed species contains simplexin and 18 other compounds. Roots, flowers and seeds are significantly more toxic than the stem, branches and leaves. We suspect that thirsty and hungry stock consumed seed and roots from flooded pastures and consumed lethal doses of simplexin. Blood tests were not good indicators of the conditions. Management strategies are suggested.

Novel alloy for speciality needle applications

A novel cobalt-chromium (CoCr) based alloy, optimised for speciality needle applications, has been benchmarked against Type 304 stainless steel in a series of mechanical test and experimental needle trials. The results reported indicate that the CoCr alloy has the potential to overcome current limitations in endoscopic and minimally invasive surgery.

Sepsis and hyperoxia effects on the pulmonary surfactant system in wild-type and iNOS knockout mice

Alterations of pulmonary surfactant and increases in inducible nitric oxide synthase (iNOS) have been implicated in the pathophysiology of acute lung injury. It was hypothesised that these two observations are related and that alterations of the endogenous surfactant, due to either sepsis or hyperoxia, would be reduced in mice lacking the iNOS gene compared to wild-type mice. Wild-type and iNOS (-/-) mice were randomised into sham or sepsis, and in a separate experiment animals were randomised to normoxia or hyperoxia exposure for 48 h. Lungs were lavaged and analysed for total surfactant levels and surfactant subfractions (large (LA) and small (SA) aggregates). Both sepsis groups had decreased SA compared to sham groups with no significant difference between the two genotypes. Mice exposed to hyperoxia had a decreased amount of total surfactant when compared to normoxia controls and there was no significant difference between the two genotypes. It is concluded that inducible nitric oxide synthase does not influence the amount of pulmonary surfactant or surfactant subfractions recovered in lavage after 18 h of sepsis or 48 h of hyperoxia.

Health hazards of air travel

Three years ago, while travelling on an aeroplane, I developed a deep vein thrombosis. I was admitted to hospital in Singapore for five days and the rest of my holiday was cancelled. I tell my story in the hope that people will read and understand my experience and reflect on the topics and questions raised. I have also included some preventative education to help people avoid circulatory problems while travelling and a brief literature review.

Clozapine as a drug of dependence

RATIONALE

In schizophrenics, clozapine has been reported to induce various withdrawal signs and rapid onset relapse to psychosis on cessation of chronic treatment.

OBJECTIVE

The study was designed to develop an animal model of one aspect of clozapine tolerance and withdrawal using core body temperature measures.

METHODS

Two groups of 15 female Wistar rats were treated chronically (b.i.d.) with clozapine at 6 or 12 mg/kg per injection for 21 days prior to cessation of drug treatment, withdrawal being studied over 4 consecutive days. Body temperatures were assessed daily throughout the study.

RESULTS

Acutely, clozapine induced dose-related hypothermia, to which complete tolerance developed in both groups, the development of tolerance being more rapid in the group treated with 6 mg/kg per injection of clozapine. During withdrawal only the group treated chronically with 12 mg/kg per injection of clozapine showed rapid onset significant hyperthermia. This dissipated progressively over days, and was completely absent after 4 days of withdrawal.

CONCLUSIONS

Clozapine induced a clear somatic withdrawal sign after chronic treatment. It is suggested that, in future research in both humans and animals, it is important to attempt to differentiate between clozapine withdrawal and clozapine withdrawal-induced relapse to psychosis. It is also important to characterise the clozapine withdrawal syndrome fully in animals; to establish the neurochemical mechanisms involved in such withdrawal; and to determine which novel antipsychotics are most efficacious in inducing clozapine-like withdrawal effects, in suppressing clozapine withdrawal, and in preventing relapse to psychosis in patients being transferred from clozapine to novel atypical antipsychotic drugs.