Local cerebral glucose utilization during intracerebral pH changes

The effect of ventriculocisternal perfusion with mock CSF with alkaline or acidic pH on the local CMRglu (LCMRglu) in the caudatoputamen was studied in artificially ventilated and relaxed rats. In control rats both lateral cerebral ventricles were perfused with mock CSF at pH 7.4. In the experimental series one cerebral ventricle was infused with normal mock CSF while the other was infused with mock CSF in which the pH was decreased or increased by changing [HCO-3]. LCMRglu was depressed in acidotic brain tissue while it was strongly increased in alkalotic brain tissue. The importance of these alterations in brain glucose metabolism for the homeostatic regulation of brain pH is discussed.     

Primary intraorbital meningioma and schwannoma--a rare association

Primary intraorbital meningioma and Schwannoma are rare tumours. For them to occur concurrently, or one following soon after another should be considered a curiosity. We present a 40 year old male who reported with proptosis of the right eye and a meningioma was removed surgically. Within 3 months symptoms recurred and a schwannoma was removed at surgery from the same site. Interesting features of the lesion are presented and discussed.     

Evaluation and assessment of new disposable strip for determination of plasma potassium concentration.

Overall laboratory reproducibility for the Ames Seralyzer and plasma potassium test strips was less than 4% within the plasma reference range; and linearity extended from 2.1 to 10.2 mmol/l. Neither bilirubin nor lipaemia interfered in the analysis and selectivity for potassium over sodium was 450:1. Laboratory comparison with automated flame photometry and an indirect ion selective electrode showed a Seralyzer bias of +0.10 (+/- 25D 0.26) and +0.11 (0.27) mmol/l. Against flame photometry, comparison of analyses by six doctors from a coronary care unit and four nurses from a renal dialysis unit showed smaller positive biases (0.06 and 0.02 mmol/l) but substantially larger error ranges (0.43 and 0.55 mmol/l, respectively). Some 49% of the nurses' and 37% of the doctors' results differed from laboratory values by more than 0.2 mmol/l. Potassium test strip results proved acceptably comparable and reproducible when produced by an experienced analyst, but greater variability in clinical hands rendered the system unsuitable for precise monitoring of potassium concentration.     

Importance of spinal noradrenergic pathways in cardiovascular reflexes and central actions of clonidine and alpha-methyldopa in the rabbit

We have examined in conscious rabbits the chronic effects of 6-hydroxydopamine (6-OHDA)-induced local lesions of the spinal noradrenaline (NA) pathways on (i) resting mean arterial pressure (MAP) and heart rate (HR), (ii) the nasopharyngeal pressor response, (iii) the sympathetic component of the baroreceptor-heart rate reflex (iv) the acute responses to intracisternal (i.c.) clonidine and alpha-methyldopa (alpha-MD), and (v) the acute NA release response produced by i.e. 6-OHDA. One month after injection of 6-OHDA (40 nmol in 4 microliters) into the first cervical spinal cord segment (C1), the NA content was reduced to 29% in C2, 45% in T4 and 61% in L3 with little non-specific damage. Basal MAP was 14% higher (P less than 0.05) than in sham-operated rabbits suggesting increased vasoconstrictor tone. Basal cardiac sympathetic tone was enhanced, but a corresponding increase in cardiac vagal tone resulted in little net effect on resting HR in the spinal NA-depleted group. Spinal NA lesions attenuated the nasopharyngeal pressor reflex by 27% in baroreceptor-intact rabbits and by 38% in sino-aortically denervated (SAD) animals. The lesion did not affect HR range, gain and BP50 of the sympathetic baroreflex. In SAD rabbits, the acute MAP responses to i.c. 6-OHDA (early hypotension, late hypertension) were not affected by spinal NA depletion, but the early fall in HR (cardiac sympathetic inhibition) was abolished. The hypotension produced by i.c. clonidine or alpha-MD was not affected by the lesion, probably because many of the NA terminals in the lower thoracic and upper lumbar cord were still intact. Our results suggest that intraspinal NA fibers have a tonic inhibitory action on spinal preganglionic vasoconstrictor and cardiac motoneurons. The spinal NA neurons affecting vasomotor tone (but not cardiac sympathetic tone) are in turn inhibited by higher vasomotor centers receiving projections from the arterial and trigeminal afferents and thereby participate in vasoconstrictor reflexes.     

Alcohol and liver injury: dose-related or permissive effect?

Studies addressing the risk of development of cirrhosis of the liver in relation to alcohol consumption have been based on comparisons at the aggregate population level and, at the individual level, on case-control studies and cohort studies, and on retrospective and prospective assessment of alcohol consumption. The ideal, but unfeasible, study design for estimation of the risk function is a prospective monitoring of alcohol consumption and recording of the rate of development of cirrhosis per unit of time. Two recent studies, approaching this design, suggested that above a rather low, but not precisely determined, level of alcohol consumption the risk of development of cirrhosis is not further influenced by the amount of alcohol consumed. A critical analysis of previous studies suggests that this risk function is actually compatible with their findings. The contention that alcohol abuse has a permissive rather than a dose-dependent role in the development of alcoholic liver injury encourages research into the additional factors that must act before the liver injury occurs.     

Anti-idiotypic antibodies against a monoclonal antibody specific for the trichothecene mycotoxin T-2

A BALB/c murine monoclonal antibody against the trichothecene mycotoxin T-2 was generated. The antibody, designated HD11, specifically bound T-2 mycotoxin. The binding of HD11 to T-2 conjugated to bovine serum albumin was inhibited by free T-2 toxin but not by the water-soluble heterocyclic guanidines saxitoxin and tetrodotoxin. The T-2 detection limit in an enzyme-linked immunosorbent assay with HD11 was in the nanogram range. The in vitro cytotoxicity of T-2, as measured by the inhibition of radiolabeled leucine uptake of the human epidermoid carcinoma Hep-2 and KB cell lines, was completely reversed by the addition of HD11. Rabbit anti-idiotypic antibodies specific for HD11 were generated and characterized.     

Liver transplantation: patients' experiences

The Dutch orthotopic liver transplant programme was evaluated recently. This article focuses on the physical functioning, the pattern of activities, the social functioning and the level of wellbeing of 31 transplant patients. Data were generated by means of questionnaires and interviews. The majority of the patients look upon themselves as 'healthy'. Their physical potential has greatly improved. Three-quarters of the patient group think they are able to go back to work. However, from the interviews it appears that one third of the patient group suffered from more or less serious psychological problems following transplantation.