Potassium concentration in equine red blood cells: normal values and correlation with potassium levels in plasma

The concentration of potassium in plasma and in red blood cells was determined in 948 horses. The coefficient of correlation between the two parameters was low. In 436 of these horses, which were clinically healthy, the red blood cell potassium (RBCK+) levels did not fit within a normal distribution curve, but a bimodal distribution was observed with a section point at 90 mmol/litre. In 90 per cent of these normal horses, mean RBCK+ content was 97.5 mmol/litre. In the remaining 10 per cent, mean RBCK+ concentration was 93.8 mmol/litre. A subdivision into a 'low potassium group' and a 'high potassium group' was made. In 10 out of 15 horses in the 'low potassium group', bimonthly sampling over a period of one year showed that RBCK+ content remained low. In the remaining five horses an increase was observed.

Determination of red blood cell potassium content in horses with diarrhoea: a practical approach for therapy

The concentration of potassium in the red blood cells in 15 horses with severe diarrhoea was determined. The red blood cell potassium content (RBCK+) was low compared with levels obtained in normal horses. The decrease in the RBCK+ was used to evaluate the total body potassium deficit. This calculated amount was administered orally, following each RBCK+ determination. In those horses which recovered, RBCK+ content returned to normal levels. During treatment, refilling of the red blood cells with potassium occurred only gradually as long as the diarrhoea persisted. In each case, oral loading with the calculated dose resulted in an improvement of the general condition and no side effects were observed. The importance of using RBCK+ levels as a diagnostic and therapeutic parameter is discussed.

Esterification of cholesterol and lipid-soluble vitamins by human pancreatic carboxyl ester hydrolase

Human pancreatic carboxyl ester hydrolase is shown to catalyse the esterification of cholesterol and lipid-soluble vitamins A, E and D3 with oleic acid. The acitivity requires the presence of bile salts, and the trihydroxylated or the 3 alpha, 7 alpha dihydroxylated bile salts are better activators than the 3 alpha, 12 alpha dihydroxylated bile salts. The hydrolyzing and synthetizing activities of human pancreatic carboxyl ester hydrolase are separated by a large pH range since the synthesis of cholesterol esters is optimal at pH 5.25 and the hydrolysis of cholesterol and vitamin E esters is optimal at pH 8.0. From the comparison of the catalytic constants determined for the hydrolyzing and synthetizing activities and from the pH dependence of the two activities, it appears that human carboxyl ester hydrolase plays an important part in the intestinal lumen. The role of the enzyme in the esterification of cholesterol and lipid-soluble vitamins is questionable.

[Chédiak-Higashi disease (report on a new case) (author's transl)]

A typical case of Chédiak-Higashi disease is reported in a French four years old boy (no parents consanguinity). The clinical aspect of oculo-cutaneous and pilar hypopigmentation, associated with recurrent infections led to the diagnosis of C. H. disease which was confirmed by the presence of giant leukocytes granulations in the blood and giant melanosomes in epidermal melanocytes; these giant pigmented granules, are made of a limiting unique membrane with granular matrix and periodic filamentous structures, which correspond to stade I, II and III melanosomes. In keratinocytes, melanosomes are rare, never isolated and scattered in cytoplasm, but grouped in giant melanosomes complexes. No specific immunity deficiency is found in this patient but the chemotaxis of neutrophil polymorphonuclear leukocytes was decreased but restored by levamisole treatment. Concanavaline A Cap formation by polymorphonuclear leukocytes was abnormally increased, but returned at a normal level after cyclic GMP incubation and levamisole treatment. Unfortuntely, the patient died soon after accelerated phase had begun, in an anatomo-clinical picture of pseudo-lymphoma. A pathogenic discussion of CH disease is presented with the help of a study of 102 cases of literature.

The two human trypsinogens: catalytic properties of the corresponding trypsins

The catalytic properties of the two human trypsins obtained from purified trypsinogens have been studied. The catalytic rate constant kcat and the pK of the ionisable residue implicated in the active site have been determined with Bz-Arg-OEt. The hydrolysis of Tos-Arg-OMe by human trypsins does not follow the simple Michaelis-Menten scheme and indicates a difference in the conformational flexibility of the active site-regions of the two enzymes. Both enzyme are readily autolyzed and calcium ion plays a fundamental role in stabilizing trypsin activity. However trypsin 2 self-digests more rapidly than trypsin 1. These results are a prerequisite to the elucidation of the fate of pancreatic enzymes in human digestive tract.