The synchronization of ventilation and locomotion in horses (Equus caballus)

Cine film and synchronized records of respiratory flow were obtained from Thoroughbred racehorses cantering on a treadmill at speeds of 9 and 11 m s-1. Horses and some other galloping and hopping mammals link their breathing and locomotion, taking exactly one breath per stride. Three theoretical mechanisms by which the movements of locomotion might drive ventilation are considered. (i) Flexion of the lumbosacral joint and the resulting forward sweep of the pelvis pushes the viscera against the diaphragm. However, back flexion lags behind ventilation at 11 m s-1 and could not exclusively drive ventilation at this speed. (ii) Loading of the thorax by the impact of the forelimbs with the ground might force air out of the lungs. If the respiratory system were damped sufficiently to perform as this mechanism requires, the work of driving ventilation would make up approximately 15% of the total work of running. In comparison with other estimates of the work of ventilation this seems improbably high. (iii) The observed phase relationship between displacements of the viscera, caused by the accelerations of the body during running, and respiratory airflow is not consistent with a tuned visceral piston mechanism driving breathing. Thus, it would seem likely that back flexion is likely to contribute towards driving ventilation but loading of the thorax and the visceral piston mechanism do not.

Some properties of the mammalian locomotory and respiratory systems in relation to body mass

Video and cine films of mammals running at the trot-gallop transition were analysed to measure breathing frequencies. Breathing frequency at the trot-gallop transition (fb, in Hz) was shown to decrease with increasing body mass (M, in kg) and was described by the equation fb = 5.08 M-0.14. The stiffness of the thorax and diaphragm of mice, rats, rabbits and wallabies was calculated and this, together with the mass of the viscera, was used to calculate the natural frequency of the system (nft, in Hz). The relationship between nft and body mass can be described by the equation nft = 5.02M-0.18. The significance of these results is discussed in relation to models of mechanical linkage between respiratory and locomotory movements.

The effect of ascorbate supplementation on oxidative stress in the streptozotocin diabetic rat

An increase in oxidative stress may contribute to the development of diabetic complications. The key aqueous-phase chain-breaking antioxidant ascorbate is known to be deficient in diabetes, and we have therefore investigated the effects of ascorbate supplementation on oxidative stress in the streptozotocin diabetic rat. Markers of lipid peroxidation (malondialdehyde [MDA] and diene conjugates) were increased in plasma and erythrocytes of untreated diabetic animals, and levels of the antioxidants ascorbate and retinol were reduced. Plasma tocopherol was unchanged. Insulin treatment normalized MDA and ascorbate levels, although ascorbate metabolism remained disturbed, as indicated by increased levels of dehydroascorbate. High-dose ascorbate supplementation in the absence of insulin treatment restored plasma ascorbate to normal and increased plasma retinol and tocopherol levels. However, MDA and diene conjugate levels remained unchanged, possibly as a result of increased iron availability. High-dose ascorbate supplementation should be approached with caution in diabetes, as ascorbate may exert both antioxidant and prooxidant effects in vivo.

Magnesium status and digoxin toxicity

1. Eighty-one hospital patients receiving digoxin were separated into groups with and without digoxin toxicity using clinical criteria. Serum digoxin, sodium, potassium, calcium, creatinine, magnesium and monocyte magnesium concentrations were compared. 2. Subjects with digoxin toxicity had impaired colour vision (P less than 0.0001, Farnsworth-Munsell 100 hue test) and increased digoxin levels (1.89 (1.56-2.21) vs 1.34 (1.20-1.47) nmol l-1, P less than 0.01) (mean (95% confidence limits], though there was considerable overlap between two groups. 3. Subjects with digoxin toxicity had lower levels of serum magnesium (0.80 (0.76-0.84) vs 0.88 (0.85-0.91) mmol l-1, P less than 0.01) and monocyte magnesium (6.40 (5.65-7.16) vs 8.76 (7.81-9.71) mg g-1 DNA, P less than 0.01), but there were no significant differences in other biochemical parameters. A greater proportion of toxic subjects were receiving concomitant diuretic therapy (20/21 vs 37/60, P less than 0.05). 4. Magnesium deficiency was the most frequently identified significant electrolyte disturbance in relation to digoxin toxicity. In the presence of magnesium deficiency digoxin toxicity developed at relatively low serum digoxin concentrations.

Serum neurone specific enolase (NSE) levels as an indicator of neuronal damage in patients with cerebral infarction

A radioimmunoassay has been developed and used to measure serum neurone specific enolase (NSE) concentrations in 24 patients, following cerebral infarction. A significant correlation between cerebral infarct volume and maximum serum NSE concentration was observed (P = 0.047). Serum NSE was also assayed at times 24, 48, 72 and 96 h post ictus. At 72 h a significant correlation existed between serum NSE levels and infarct volume (P = 0.012), and levels appeared to be approaching statistical significance at 48 h (P = 0.067). No correlation existed at 24 and 96 h. In addition serum concentrations of NSE were compared to clinical outcome as determined by the Glasgow Outcome Score. Using the Mann-Whitney U test, there was no significant difference in maximum NSE level between patients graded 1-3 on the Glasgow Outcome Score and those graded 4 and 5. However, further studies are required on a larger population to more completely assess this. NSE may prove to be a useful marker of neuronal damage in the study of stroke, with particular application in the assessment of treatment.

Measurement of malondialdehyde in plasma by high performance liquid chromatography with fluorimetric detection

The thiobarbituric acid test for malondialdehyde is widely used as an indicator of lipid peroxidation and free radical activity. We describe a simple and sensitive high performance liquid chromatographic (HPLC) method for measuring the malondialdehyde-thiobarbituric acid adduct using fluorimetric detection. Extraction into organic solvent or other complex sample preparation is not required and the assay is sensitive to less than 0.05 mumol/L. This method could easily be applied to any setting where a measure of lipid peroxidation is required.

Power output and the frequency of oscillatory work in mammalian diaphragm muscle: the effects of animal size

Bundles of muscle fibres were isolated from the diaphragm of mouse, rat and rabbit. Mean oscillatory power output was determined during phasic stimulation and imposed sinusoidal length changes. Maximum power output was measured over a range of cycle frequencies. The cycle frequency for maximum power output (fopt) decreased with increasing body mass and was described by the equation, fopt = 4.42M-0.16, where M is body mass. A very similar relationship has been reported between body mass and the frequency of the trot-gallop transition in terrestrial, quadrupedal mammals [Heglund et al. (1974), Science 186, 1112–1113), and the significance of this similarity is discussed.

Transient release of lipid peroxides after coronary artery balloon angioplasty

Free radical production may cause myocardial damage during reperfusion of ischaemic myocardial tissue; when free radicals interact with polyunsaturated fatty acids or their esters, lipid peroxides are produced. A product of lipid peroxidation, malondialdehyde, was measured in 10 subjects with stable angina who underwent angioplasty of a proximal high-grade stenosis (over 90%) of the left anterior descending coronary artery. In all subjects the duration of balloon occlusion was 60 s. Blood was withdrawn from the great cardiac vein immediately before balloon inflation (T0), immediately after balloon deflation (T60), 15 s after balloon deflation (T75), and 1 min after balloon deflation (T120). There was a significant increase in malondialdehyde at T60 compared with T0 for the first balloon inflation (mean increase 0.3 mumol/l [95% confidence limits 0.1, 0.5]), and at both T60 (0.31 mumol/l [0.15, 0.47]) and T75 (0.22 mumol/l [0.04, 0.40]) for the second balloon inflation. This model could be used to assess antioxidant effects of drugs.

Initial EDAP LT-01 lithotripsy group experience in the United States

The initial United States cooperative experience with the EDAP LT-01 second generation piezoelectric extracorporeal shock wave lithotriptor using ultrasonic guidance is presented. Particular to the machine are lack of radiation exposure, no need for anesthesia, a purely outpatient procedure, no electrocardiographic problems, a high degree of safety and a paucity of complications. The equipment is described briefly. The same machine currently is being used to destroy renal and biliary stones. The results are encouraging and highly comparable to the initial experience with the earlier machines. Fragmentation rates are approximately 86%, with destruction rates of 63.4% over-all. Ultrasound localization and monitoring proved surprisingly easy to learn and were increasingly less of a problem as experience was gained. No serious complications were observed, and there were no renal losses and no deaths. Only 3 cases of steinstrasse were noted among 461 with 633 stones targeted during 595 treatments.

Reversal of pentamidine-induced hypoglycaemia with oral diazoxide

Hypoglycaemia is a common and occasionally life-threatening complication of therapy with pentamidine isethionate. We observed inappropriately elevated insulin levels in a patient with Pneumocystis carinii pneumonia and pentamidine-induced hypoglycaemia. Oral diazoxide was effective in reversing the marked hypoglycaemia. Pentamidine may exert its hypoglycaemic effect by stimulating insulin secretion from the pancreas.

Testosterone secreting adrenal cortical adenomas

We report the hormonal and radiological evaluation of two cases of adrenal cortical adenomas that secreted testosterone exclusively. We discuss some of the pitfalls in the diagnosis of this lesion, and summarize the current knowledge of the characteristic hormonal features in the two cases and the 12 cases previously reported.

Multifocal eosinophilic granuloma ("Hand-Schuller-Christian disease"). Report illustrating H-S-C chronicity and diagnostic challenge

We have described an unusual case of multifocal eosinophilic granuloma ("Hand-Schueller-Christian disease") in a middle-aged woman. The case underscores the varied and subtle nature of the disease presentation and the extent to which many organ systems may become involved. Unusual features of her case include atypical bone roentgenograms, cutaneous anergy, panhypopituitarism and evidence of diffuse central nervous system dysfunction. Several features of multifocal eosinophilic granuloma present in the older age group are different from those presenting in children and young adults. Finally, multifocal eosinophilic granuloma may present all the clinical and laboratory features of a progressive, chronic disease.

Inverted papilloma of bladder

The fifth reported case of a rare variant of transitional papillary tumor of the bladder termed inverted papilloma is reported with a brief review of the literature. This tumor is likely to be confused with invasive malignant papillary carcinoma although it has adistinct histologic pattern, and it is for this reason that attention is drawn to the entity.