A bovine stress syndrome associated with exercise-induced hyperthermia.

OBJECTIVE: To investigate an exercise-induced bovine stress syndrome under field and controlled experimental conditions. DESIGN AND PROCEDURE: In the field study, cattle affected with the stress syndrome were observed while they were grazing and during normal mustering using horses. This study served to define the clinical nature of the syndrome. The experimental study utilised three affected and five normal unaffected cattle. These animals were compared on the basis of their response to a defined exercise program, which consisted of walking 3.6 km in 2 h. Blood samples and measurements of respiratory rate, ambient temperature and rectal temperature were taken immediately before exercise, and at 0.5, 1.0, 1.5 and 2.0 h during the exercise and 24 h later. Clinical and blood constituent data were subjected to standard analysis of variance and repeated measures analysis. RESULTS: In the field study, affected cattle were observed to show abnormally anxious and hyperactive behaviour. This behaviour was exhibited by affected cattle during the experimental exercise program where it was shown to be accompanied by hyperthermia and hyperventilation. The experimental study showed that affected cattle developed metabolic acidosis and became hyperglycaemic. Their plasma creatine kinase activity remained markedly increased at 24 h after exercise but other clinical and blood constituent variables had returned to normal values. CONCLUSION: The clinical and biochemical changes detected in affected cattle were consistent with exercise-induced malignant hyperthermia.

Spasticity and white matter abnormalities in adult phenylketonuria.

A 19 year old male with phenylketonuria (PKU) developed a spastic paparesis 8 months after stopping his restricted phenylalanine diet. CT and MRI showed abnormalities of the deep cerebral white matter, and visual evoked response latencies were prolonged. The spasticity gradually improved over several months after resuming the PKU diet. A repeat MRI scan was unchanged. His brother also had PKU and ceased dietary restrictions, but his only neurological abnormality was a slight increase in the deep tendon reflexes of the lower limbs. CT and MRI of his brain was normal. DNA analysis showed that both brothers were homozygous for the same PKU mutation. These patients demonstrate that reversible neurological signs may develop in patients with classic PKU after ceasing dietary restrictions and that these may be associated with abnormalities seen on neuro-imaging.

Routine use of hair root or buccal swab specimens for PCR analysis: advantages over using blood.

We report the use of hair roots and buccal cells as specimens of choice for DNA analysis of genetic diseases in a service laboratory. Our protocols using these specimen types show superiority to those using blood specimens in the areas of collection, transport, storage and overall cost. Our experience using these specimen types for 319 cystic fibrosis delta F508 mutation tests and 62 Leber's hereditary optic neuroretinopathy mutation tests leads us to recommend that hair roots and buccal cells should be evaluated as specimens of first choice when developing PCR DNA analysis.

Monoclonal immunoglobulin bands in the cerebrospinal fluid.

Isoelectric focusing and immunofixation allow the detection of abnormal immunoglobulin bands in the cerebrospinal fluid (CSF). In normal subjects, the immunoglobulins in the CSF are derived from serum. In inflammatory disorders of the nervous system, there may be intrathecal immunoglobulin synthesis usually seen as oligoclonal bands confined to the CSF. Monoclonal immunoglobulin bands in the CSF are not common. We surveyed 1490 CSF samples, and found that a total of nine had a monoclonal immunoglobulin band and that in three this was not present in the serum. Of these three, one patient had chronic inflammatory demyelinating polyneuropathy and the antibody may have been secreted by lymphocytes which had infiltrated the nervous system. The other patients had either lymphoma or lymphomatoid granulomatosis within or adjacent to the nervous system and the monoclonal immunoglobulin was probably secreted by B lymphocytes within those lesions.

Factors affecting the concentrations of ferritin in serum in a healthy Australian population.

We measured by different techniques the ferritin concentration in serum in two large asymptomatic Australian population samples: 1367 bank employees and 601 insurance corporation employees. Ethanol intake, diet, the frequency of blood donation, smoking and exercise habits, and past medical history were documented. The median concentration of ferritin in serum varied according to age and sex, but was generally higher than in previously reported populations under age 65 years. Results for the two population samples were in close agreement. Apart from the blood donation status, the most important factors influencing the concentration of ferritin in serum were ethanol intake in men and diet in women. Heavy ethanol intake was associated with increased values, even among men without evidence of liver disease. We conclude that the reference range for ferritin concentration in serum in the Australian population should be significantly increased and should be related to age as well as sex. This study emphasizes the need to determine local reference ranges for ferritin concentrations in serum.

Prevalence of haemochromatosis amongst asymptomatic Australians.

We determined the prevalence of iron overload due to homozygous haemochromatosis in an asymptomatic Australian (predominantly Caucasian) population by surveying 1968 employees of two large corporations. Subjects were screened by measurement of transferrin saturation and serum ferritin concentration and, in all subjects with elevation of both indices, percutaneous liver biopsy was performed to establish whether significant iron overload was present. The prevalence of iron overload due to haemochromatosis in this population was 0.36%. The prevalence rate was not significantly different between males and females, suggesting that this autosomal recessive disease is expressed equally in females given an adequate dietary iron supply. The positive predictive value of a transferrin saturation consistently greater than 45% together with an elevated serum ferritin concentration was 64%. It is concluded that the prevalence of significant iron overload due to homozygous haemochromatosis warranting treatment is approximately 1:300 and that transferrin saturation should be included in existing adult health screening programmes.

Nitromethane interferes in assay of creatinine by the Jaffé reaction.

A patient who ingested a methanol/nitromethane mixture (model airplane fuel) showed an apparent plasma creatinine concentration of 8.0 mmol/L by the Jaffé reaction when the actual creatinine concentration, as measured by a specific enzymatic method, was 0.09 mmol/L. This effect was due to nitromethane in the plasma. Interference by nitromethane with the determination of creatinine by reaction with alkaline picrate (the Jaffé reaction) has not previously been reported. When nitromethane was added to plasma, the apparent creatinine measured was linearly related to the amount of nitromethane added. Comparison of spectral changes occurring during creatinine/picrate and nitromethane/picrate reactions show substantial similarity, suggesting a similar structure for the products. Although the findings are of interest for both their toxicological and analytical implications, the main interest lies with their suggestion of a model system for future investigation of the Jaffé reaction.