Decreased antidiuretic response in diabetes insipidus during prolonged treatment with carbamazepine presumably due to enzym-induction

Carbamazepine (CA)-induced antidiuresis and fluorescence in urinary cortisol assay was compared during short-term and prolonged treatment in 3 patients with pituitary diabetes insipidus. The fluorescence induced by excreted CA-metabolite(s) (probably CA-10-11 epoxide and its derivatives) was used for the rough clinical estimation of the rate of metabolic elimination of the drug. A marked decrease was observed both in the antidiuretic response induced by CA and excretion of CA metabolite(s) during prolonged treatment - with a fixed dose of CA. These findings suggest that diminishing antidiuretic effectiveness might be due to auto-induction of CA. Auto-induction of CA may explain the delay in improvement of renal concentrating operation in patients with DI during long-term treatment with fixed doses of CA. Another clinical consequence of this mechanism may be the prevention of the development of water intoxication in neuro-psychiatric patients undergoing chronic treatment with CA.     

Study on the relationship between plasma prolactin levels and androgen metabolism in man

The purpose of the study was to investigate the effect of hyperprolactinemia on the metabolism of androgens in man. A group of 6 normal men was treated for 4 consecutive days, on separate periods, with Sulpiride which is known to raise plasma prolactin (PRL) concentration. The effect of the treatment on plasma steroids was verified in basal conditions and under stimulation by HCG. In the controls, a parallel rise in testosterone (T) and dihydrotestosterone (DHT) was observed in response to HCG stimulation. In experimental hyperprolactinemia, the rise in T in response to HCG, similar to that of the controls, was accompanied by a markedly diminished rise in DHT. Similar results were observed in a patient with hyperprolactinemia following apparent accidental section of the pituitary stalk. These data demonstrate the interference of increased levels of PRL in the metabolism of testosterone into the active DHT form by 5alpha-reductase. They suggest that this mechanism could possibly impair the gonadal function in man.     

Aldosterone secretion during high sodium cerebrospinal fluid perfusion of the brain ventricles

Conscious sheep with permanent indwelling cannulae in the lateral ventricles and the cisterna magna were Na depleted and then perfused for 9 h with an artificial CSF solution. There were 3 experimental groups: Group I (n=5) received perfusion with aritifical CSF containing NA 170 MEq./1, Group II (n=7) received perfusion with artificial CSF containing Na 145 mEq./1, Group III (n=7) received no perfusion. In Group I the blood aldosterone level fell from 26.4 +/- 7.4 to 8.6 +/- 2.3 ng/100 ml by 9 h after perfusion. There was no significant change in plasma [Na] or [K], blood angiotensin II or plasma renin concentration. Blood cortisol and corticosterone levels rose. There was also a fall in post-perfusion. Group III showed no significant change in blood aldosterone concentration. Multivariate statistical analysis showed that the fall in aldosterone levels during 170 mEq./l Na perfusion could not be accounted for by changes, either alone or together, of ACTH as evidenced by alteration in blood cortisol or corticosterone, or by change of plasma [Na], [K] or renin concentrations. This data supports the hypothesis of an additional factor which may be of CNS origin being involved in the control of aldosterone secretion.     

Morphological and physiological characteristics of Gemmiger formicilis isolated from chicken ceca

Morphological and physiological studies were made on chicken cecal isolates of the strictly anaerobic bacterial species Gemmiger formicilis. Structural features (phase-contrast and electron microscopy) of these microorganisms indicate they (i) are highly pleomorphic, (ii) possess a trilaminar cell wall like gram-negative bacteria, (iii) exhibit an unusual growth process characterized by polar swelling (resembling budding bacteria), and (iv) grow into elongated cells when exposed to a subinhibitory concentration of penicillin. The morphological data presented suggest that this species has a rod-shaped structure. These bacteria ferment a variety of sugars to produce formic, butyric, and lactic acids. There appear to be two groups of Gemmiger, one producing primarily lactate and the other producing formate as major fermentation metabolites. Growth of six strains in a basal medium, consisting of Trypticase, minerals, carbohydrate, Na2CO3 buffer, and cysteine as reducing agent, was stimulated by rumen fluid and yeast extract. Volatile fatty acids partially replaced the requirement for rumen fluid with some strains. Single deletions of vitamins (from a defined vitamin mixture) indicated that pantothenate, riboflavin, and thiamine were highly stimulatory to growth of the organism in a medium containing rumen fluid and Trypticase as source of vitamins. Other vitamin requirements were not studied.     

A highly sensitive C-terminal specific radioimmunoassay for human parathormone as a routine method (author's transl)

The basis for the radioimmunoassay of parathormone (PTH) as a routine method is a new sheep antiserum and a labelled PTH stabilised by a modification of the purification technique. The antiserum is obtained by immunisation with pig and cattle parathormone, it is C-terminal specific and is used in the assay in a final dilution of 1:35000. The affinity to human PTH is markedly greater than of the antisera used up to now. Two purification steps of 125J labelled bovine PTH lead to a tracer with a nonspecific binding of approximately 5% which increases to approximately 10% within 6 weeks. All normal sera investigated so far were measurable quantitatively (normal range 0.7 to 2.5 mul/equiv.). The lower sensitivity range was at 0.3 mul/equiv. All patients with chronic renal insufficiency and dialysis patients have an increased PTH concentration (3.9 to greater than 20 mul/equiv.). This also applies to patients with primary hyperparathyroidism (2.9 to greater than 20 mul/equiv.).     

Rheographic assessment of cerebral blood volume and correlations with changes in intracranial pressure

The authors present a four electrode rheographic technique for simiquantitative continuous measurement of CBV, by examining changes in cerebral tissue impedance induced by changes in blood content of the brain parenchyma. Correlation between the data obtained and ICP measurements permits conclusions regarding the behaviour of the cerebral blood bed. pCO2 regulates CBV, and the phenomenon is reversible according to a hystereris shaped time course in acute experiments. The rebound of ICP after sudden injections of CSF into the cisterna magna is of a vasogenic nature. Changes in CSF volume induce contrary changes in CBV. Pharmacological effects can be studied. The validity of the method is discussed.