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Biomedical subjects

M Imler

Publications and source records attributed to M Imler.

At least 55 records · Page 3Linked to original sources
PubMed1986

Cephalic phase insulin secretion in relation to food presentation in normal and overweight subjects.

The existence of a preabsorptive insulin reflex is well known in animals but remains controversial in humans. Glycemia and insulin variations following olfactive and visual presentation of a standard meal were studied in 25 subjects, 10 of them (5 men and 5 women) of normal weight and 15 overweight (7 men and 8 women), after a 15 hour fast. Blood samples were collected continuously, every minute for 16 minutes after the meal was presented. The presentation produced an early blood insulin increment, variable in magnitude and time course and occurring between the 3rd and 9th minute, in both normal and overweight subjects. Glycemia variations were not significant. Our study demonstrated a positive correlation between the reflex insulin release, body weight and a conscious effort to maintain current body weight. However, the differences between overweight and normal subjects remained small. The physiological and psychological determinants of the cephalic phase of insulin secretion are discussed.

Adult↗
PubMed1985

[Treatment of severe hyperthyroidism by plasma exchange. Clinical and biological efficacy. 8 cases].

The effectiveness of plasmapheresis was evaluated in 8 patients with severe thyrotoxicosis of diverse origin and clinical manifestations, who underwent a total of 22 plasma exchanges. The method proved rapidly effective in controlling the symptoms in 6 cases. No adverse reaction was noted. In all patients plasma exchanges significantly reduced plasma concentrations of total thyroxine and triiodothyronine and of thyroxine-binding globulin, without effect on free thyroxine and triiodothyronine fractions. The satisfactory clinical results obtained can only be explained by displacement of thyroid hormones from the intracellular compartment. The hormonal variations observed were proportional to the initial hormone concentrations, to the amount of thyroxine-binding globulin removed and to the plasma volume purified. It is concluded that plasmapheresis rapidly extracts thyroid hormones and is therefore useful in the treatment of acute severe thyrotoxicosis.

Adult↗
PubMed1985

Decrease of valproate-induced hyperammonemia in normal subjects by lipid ingestion.

Sodium valproate (VPA), a branched short-chain fatty acid, always causes a hyperammonemia of renal origin in fasting man. The intake of medium-length, straight-chain fatty acids abolishes the VPA-induced hyperammonemia, and VPA free fraction increases concomitantly. Accordingly, fatty acids could be useful in preventing and treating hyperammonemia-accompanied stuporous states which are complications of VPA medication.

Ammonia↗
PubMed1985

Adaptation of hepatic ammonia metabolism after chronic valproate administration in epileptics treated with phenytoin.

The effects of phenytoin (PHT) on the modifications of ammonia (NH+4) metabolism caused by sodium valproate (VPA) are here studied in order to identify the drug combinations susceptible of evoking stuporous states in epileptics, a rare condition attributed to a hyperammonemic encephalopathy induced by VPA. During chronic treatment with PHT or VPA-PHT, the acute injection of VPA increases the kidney's output of NH+4. During chronic PHT treatments, the acute injection of VPA modifies the liver's NH+4 metabolism and the arterial hyperammonemia is high (mean = 90 mumol/l). During chronic VPA-PHT treatments, the acute injection of VPA does not affect the hepatic NH+4 metabolism, suggesting that adaptation occurs, and the arterial hyperammonemia is moderate (mean = 60 numol/l). Disturbances of the hepatic adaptive mechanisms may explain certain complications observed during multiple-drug regimens.

Adaptation, Physiological↗
PubMed1984

[Renal glutamine metabolism in man during treatment with sodium valproate].

The administration of 1500 mg sodium valproate to 20 patients provoked in the kidney an increased glutamine uptake correlated with an increased ammonia release, as shown by the changes of the renal arterial-venous concentration differences of glutamine and ammonia. VPA's action on the renal cell may perhaps constitute a valid model for elucidating the effects of this drug on neurons.

Adult↗
PubMed1984

[Hyperammonemia and decrease of growth and nocturnal locomotion in rats with portal stricture and uremia].

In order to make clearer the pathogenesis of hepatic coma, the clinical tolerance of progressive levels of chronic hyperammonemia were studied in the rat. Increases of blood ammonia in the range of 200 to 600 micrograms/dl were produced within 4 weeks by stricture of the portal vein associated with progressive rises in blood urea resulting from reduction of the renal mass and/or addition of urea to the food. The portal stricture produces a collateral circulation allowing a hepatic bypass of portal blood and the ammonia level of this blood is proportional to the amount of circulating and alimentary urea hydrolyzed in the digestive tract. Only the highest hyperammonemias were associated with decreased nocturnal locomotion of the rats and decrease in the growth rate. The latter was correlated with the ammonia levels. No animal presented signs of coma. These results suggest a good cerebral tolerance by the rat of important chronic hyperammonemias which however seem to have an anorexic effect.

Ammonia↗
PubMed1983

[Apoproteins A1 and B as markers of the severity of cirrhosis].

Since apolipoproteins A1 and B (Apo A1 and Apo B), which are the quantitatively predominant fractions of plasma lipoproteins, are synthetized and/or metabolized in the liver, their variations could represent a significant prognostic factor in patients with cirrhosis. In order to test this theory, the concentrations of Apo A1 and Apo B were measured in 43 patients with confirmed cirrhosis and were found to be reduced. These changes correlated with a number of biochemical tests measuring hepatic function and indicating severe cirrhosis, as well as with a clinico-biological severity index based on these biochemical tests and on the importance of clinical complications during the course of the disease. It is concluded that Apo 1 and Apo B determinations constitute a valuable index of liver synthetizing function.

Apolipoprotein A-I↗
PubMed1983

[Quantitative evaluation of hormonal extraction performed by continuous plasma exchange in euthyroid patients. Application to the treatment of severe hyperthyroidism].

Plasma exchanges (PE) have been successfully used in the treatment of thyroid storm. The dramatic results obtained (as in the case reported here) have prompted the authors to evaluate the effects of PE on plasma thyroid hormone (T4, T3 and unbound T4) levels and thyroxine-binding globulin (TBG) levels in 5 euthyroid patients. PE of one blood volume consistently produced a significant decrease in T4, T3 and TBG levels without changes in unbound T4 or TSH. Hormone extraction was proportional to the volume of blood removed and correlated with the amount of TBG extracted. Compared with the estimated total plasma content, the percentage of unbound T4 extracted was superior to that of total T4, which suggests release of free hormones from the intracellular compartment. Repeated PE in the same patient resulted in a transient decrease in T4 without changes in TSH. These results indicate that PE constitutes a fast, simple and effective means of removing thyroid hormones in all emergencies related to thyrotoxicosis. The fact that TSH levels remain stable after PE shows that the thyroid balance in euthyroid subjects is unaffected by this method.

Evaluation Studies as Topic↗
PubMed1983

Sodium valproate-induced hyperammonemia in the rat: role of the kidney.

The intravenous injection of sodium valproate (VPA) 200 mg/kg provoked in fasting rats a 100% increase in the arterial NH+4 concentration by the 10th min. The increase persisted at this level for at least 100 min. Simultaneous measurements of NH+4 and glutamine concentrations in the carotid artery, renal vein and suprahepatic vein showed that there were increases in the release of NH+4 and the uptake of glutamine by the kidney while the [NH+4] of suprahepatic venous blood remained stable. In binephrectomized rats injected with VPA, NH+4 levels did not change. These results suggest that the VPA-induced arterial hyperammonemia depended on the accelerated catabolism or possibly the reduced synthesis of glutamine by the kidneys. The liver of fasting rats does not seem to play a preponderant role in the VPA-induced hyperammonemia.

Ammonia↗
PubMed1983

[Sodium valproate: a hyperammonemic drug. Study in the epileptic and healthy volunteer].

Sodium valproate (VPA) consistently induces an arterial hyperammonemia in epileptics tolerant of this drug and in normal subjects. The hyperammonemia appears with the first oral or intravenous dose of the drug, 15-25 mg/kg, and is established within minutes following drug absorption. In 20 epileptics treated with VPA alone for 4 days, the mean arterial ammonemia measured 2-3 h after breakfast and the day's first VPA dose was 72 +/- 9 mumols/l in non-alcoholics, and 77 +/- 7 mumols/l in alcoholics. Hyperammonemia persisted during chronic treatment; in 10 epileptics who had had received only VPA for over a month, the mean hyperammonemia was 87 +/- 6 mumols/l (normal value means +/- 2 SD = 28 +/- 12 mumols/l). The ammonemia varied in the course of the day; sharp peaks 7 or more times the base value were observed. These variations, differing among subjects, depended on the VPA plasma concentration, and above all on the meal composition and the relative timing of the meal and the drug administration. No secondary effects were seen; in particular, hepatic and pancreatic tests were normal. The hyperammonemia would seem to be due to physiopathological mechanisms other than those giving rise to the hepatic complications occasionally observed with VPA. The permanence and the extent of the hyperammonemia raise questions as to its origin, its relation to the stuporous states induced by VPA, and its eventual repercussions on the functioning of neurons.

Ammonia↗