Renal Na+, K+-ATPase in Dahl salt-sensitive rats: K+ dependence,effect of cell environment and protein kinases

Na⁺, K⁺-ATPase in renal epithelial cells plays an important role in the regulation of Na⁺ balance, extracellular volume and blood pressure. The function of renal Na⁺, K⁺-ATPase in Dahl salt-sensitive (DS) rats, an animal model for salt-sensitive hypertension, and Dahl salt-resistant (DR) rats has been studied. In Na⁺, K⁺-ATPase partially purified from renal cortex, affinities and the Hill coefficients for Na⁺ and K⁺ activation were similar in DS and DR rats. Only one component of low ouabain affinity site was found in both strains, indicating the presence of the al isoform. Protein kinase C and cAMP-dependent protein kinase phosphorylated Na⁺, K⁺-ATPase α subunit in DS and DR rats, and the phosphorylation by protein kinase C was associated with an inhibition of enzyme activity. The kinetic parameters for K⁺ activation were also studied in a preparation of basolateral membranes and were found to be similar in DS and DR rats. In a preparation of cortical tubule cells, Na⁺, K⁺-ATPase activity was determined as ouabain-sensitive oxygen consumption (OS Qo₂). Maximal OS Qo₂, measured in Na⁺ loaded cells, was the same in DS and DR rats. The K₀₆ for K⁺ was significantly lower in DS than DR rats (0.163 ±0.042 vs. 0.447 + 0.061 mM, P < 0.05), indicating that factors regulating Na⁺, K⁺-ATPase activity in intact cells are altered in DS rats. Kinetic parameters for Na⁺ activation in cells were the same in both strains. In summary, the function of renal Na⁺, K⁺-ATPase molecule is not altered in DS rats. The intracellular systems that regulate renal Na⁺, K⁺-ATPase activity might be different in DS and DR rats.     

Separation of the Toxic and Glutathione-Enhancing Effects of the Naturally Occuring Nitrile, Cyanohydroxybutene

Cyanohydroxybutene (CHB) is reported to be hepatotoxic in maleFischer 344 rats at an oral dose of 300 mg/kg and, while nolonger hepatotoxic, pancreatotoxic at 200 mg/kg. In addition,the 200 mg/kg dose causes a persistent elevation in hepaticand pancreatic glutathione (GSH). This study was conducted tode termine if smaller doses of CHB could cause GSH elevationin the absence of toxicity. A single oral dose of 100 mg/kgor multiple lower doses (50 mg/kg daily for 3 days or 30 mg/kgfor 6 days) caused a significant and persistent increase inpancreatic GSH, although hepatic levels were unchanged. Tenmilligrams per kilogram, even daily for 24 days, was withouteffect on hepatic or pancreatic GSH. Neither a single oral doseof 100 mg/kg nor multiple lower doses were associated with toxicity.However, when either 100 or 50 mg/kg were administered intravenously,pancreatic apoptosis was observed. In animals dosed with 100mg/kg iv, mixed histiocytic and suppurative inflammation andfrank pancreatic necrosis also developed and were associatedwith elevated plasma lipase and amylase. The animals receivingCHB intravenously also exhibited elevated GSH levels in bothpancreas and liver. This study shows that oral doses between30 and 100 mg CHB/kg can be used to elevate GSH levels withoutany pancreatotoxicity. However, a single 50 mg CHB/kg dose givenintravenously causes apoptosis, while 100 mg/kg causes severepancreatotoxicity with necrosis.     

Immunological properties of recombinant proteins of the transmission blocking vaccine candidate, Pfs48/45, of the human malaria parasite Plasmodium falciparum produced in Escherichia coli

A precondition for the development of a transmission blocking vaccine based on the sexual stage-specific surface antigen Pfs48/45 of Plasmodium falciparum is its heterologous synthesis in a native state. Here we describe the production of recombinant Pfs48/45 in Escherichia coli . Two recombinant proteins, of which one is a glutathione-S-transferase fusion protein, were produced. Enzyme-linked immunosorbent assays showed that at least a subfraction of the recombinant proteins had a conformation capable of binding transmission blocking monoclonal antibodies. However, despite the fact that both proteins were very immunogenic, they did not induce transmission blocking immunity in mice or rabbits. Immunological studies with congenic mouse strains demonstrated that immune responses could be boosted with gametocyte extracts and were not restricted to a particular class II major histocompatibility complex haplotype .     

bcl-1 REARRANGEMENT AND CYCLIN D1 PROTEIN EXPRESSION IN MANTLE CELL LYMPHOMA

Centrocytic lymphoma, or mantle cell lymphoma (MCL), is characterized by a chromosomal translocation t(11;14) (q13;q32) involving the bcl-1 locus on chromosome 11. Cyclin D1 is a cell-cycle regulatory protein essential for G1–S transition and has been identified as a potential transforming gene affected by the translocation. In this study, 32 cases of MCL were analysed for the bcl-1 rearrangement and cyclin D1 protein expression. In 17 cases, a rearrangement at the major translocation cluster of bcl-1 could be detected. Twenty-four cases exhibited nuclear cyclin D1 expression that was not detectable in other B-cell lymphomas ( n =40) or in normal B-cells. In nine MCL samples, cyclin D1 was expressed without a detectable bcl-1 rearrangement. The detection of a t(11;14) by means of classical cytogenetics in one of these cases, however, may suggest that this discrepancy could be due to chromosomal breakages outside the typical translocation cluster region. In two cases, a bcl-1 rearrangement was not accompanied by cyclin D1 expression. This study provides further evidence that cyclin D1 is involved in the pathogenesis of MCL and can be exploited as a diagnostic marker in the differential diagnosis of B-cell lymphomas and in the identification of MCL.     

Oral Rehydration Therapy in Malnourished Infants with Infectious Diarrhoea

ABSTRACT. The clinical response and changes in water and salt homeostasis was studied for 36 hours during oral rehydration therapy with a rehydration solution containing 60 mmol sodium/1 (ORSffl) in 14 malnourished 3- to 15-month-oId Turkish infants with acute infectious diarrhoea. All patients were successfully rehydrated with this treatment. Sodium was efficiently absorbed from the gut and water balance was rapidly restored. Because of excess fluid retention following the initial rehydration period about 50% of the patients became oedematous. Urine volume and urinary sodium excretion were found to be much lower than in well-nourished patients of the same age with acute diarrhoea who were treated in the same way. In all of the malnourished infants the serum sodium level remained within the normal range during treatment. The results show that malnourished infants retain much more fluid and sodium than infants who are in a normal nutritional state. Excessive retention of water and salt seem to be due to an inability of the kidneys to control sodium and fluid homeostasis while orally administered sodium and fluid are being absorbed from the gut. The results show that ORT is safe and efficient in the treatment of malnourished infants with acute diarrhoea. But since these infants run a high risk of developing a severe retention of fluid and salt, and consequently may develop circulatory failure due to hypervolemia during oral rehydration therapy, it is important to carefully monitor the volume of fluid that is given.     

RENAL FUNCTION IN NEWBORN INFANTS WITH HIGH HEMATOCRIT VALUES BEFORE AND AFTER ISOVOLEMIC HAEMODILUTION

ABSTRACT. Aperia, A., Bergqvist, G., Broberger, O., Thodenius, K. and Zetterström, R. (Department of Paediatrics, St Göran's Children's Hospital, Kardinska Institutet, Stockholm, Sweden). Renal function in newborn infants with high hematocrit values, before and after isovolemic hernodilution. Acta Paediatr Scand 63: 878, 1974.—To evaluate the effect of high hematocrit (secondary polycythemia) on renal function in newborn babies, 10 infants with values above 70% have been studied before and after an isovolemic hemodilution. By replacing blood with a solution containing albumin, glucose and sodium chloride the hematocrit was reduced to about 60%. Hematocrit, blood viscosity, glomerular filtration rate (single injection technique), and the renal response to an oral sodium and fluid load were determined before and after hemodilution. The fall in hematocrit was accompanied by a concomitant fall in blood viscosity. All parameters of renal function which were studied were low before hemodilution but improved after this procedure. Water excretion increased out of proportion to glomerular filtration rate. It is suggested that the reduction in renal function as seen in newborn infants with high hematocrit are secondary to an impairment of glomerular plasma flow which in turn is the consequence of high viscosity. The depression of renal function as seen in polycythemic newborn infants may cause marked changes in the handling of certain drugs.     

FAMILIAL FANCONI SYNDROME WITH MALABSORPTION AND GALACTOSE INTOLERANCE, NORMAL KINASE AND TRANSFERASE ACTIVITY

ABSTRACT. Aperia, A., Bcrgqvist, G., Linné, T. and Zetterström, R. (Department of Paediatrics, Karolinska Institute, St. Göran's Children's Hospital, Stockholm, Sweden). Familial Fanconi syndrome with malabsorption and galactose intolerance, normal kinase and transferase activity. A report on two siblings. Acta Paediatr Scand, 70:527,.–Two siblings of Turkish-Assyrian extraction, whose parents were first cousins, had poor appetite, slow weight gain and retarded psychomotor development. When given milk the galactose concentration in blood increased. An oral galactose load showed a markedly reduced capacity to metabolize galactose. Fanconi syndrome was present as in classical galactosemia. A galactose-free diet reduced the aminoaciduria but did not normalize the renal tubular function nor the children's general condition. Galactokinase and galactose-1-phosphate uri-dyltransferase activities in red blood cells were normal. The physical appearance of the children (sparse subcutaneous fat, thin extremities and distended abdomen) and the results of vitamin A and xylose absorption tests, were in accordance with a malabsorption condition. Glucose, however, seemed to be absorbed normally from the gut. There was no evidence of significant primary liver disease. Since the condition did not normalize with a galactose-free diet, an enzyme defect of galactose metabolism is unlikely. Instead, a more general transport defect with autosomal recessive inheritance is proposed.     

POSTNATAL DEVELOPMENT OF RENAL FUNCTION IN PRE-TERM AND FULL-TERM INFANTS

ABSTRACT. Aperia, A., Broberger, B., Klinder, G., Herin, P. and Zetterström, R. (Department of Paediatrics, Karolinska Institute, St. Göran's Children's Hospital, Stockholm and Huddinge Hospital, Huddinge, Sweden). Postnatal deveopment of renal function in preterm and full-term infants. Acta Paediatr Scand, 70:183, 1981. –This study has been designed to examine the effect of gestational age (GA) on the postnatal development of renal function and has been performed in pre-term (PT) infants (GA=30–34 weeks) and in full-term (FT) infants (GA=39–41 weeks). Postnatal age has ranged from 1–35 days. From 8 hour urine samples collected after spontaneous voiding and a capillary blood sample, determinations have been made of the clearance of creatinine (C_Cr), the fractional excretion of β₂-microglobulin (FE_β2) and the fractional excretion of sodium (FE_Na). In some infants receiving fluid parenterally, simultaneous determinations were made of the clearance of creatinine and inulin. As judged from this study, C_Cr is a reliable indicator of the glomerular filtration rate (GFR). GFR was almost the same in newborn PT and FT, but from 0.3–1 week of age GFR increased significantly more rapidly in FT than in PT. From 1–5 weeks of age GFR increased at approximately the same rate in PT and FT infants. The absolute value for GFR in 3–5 weeks old infants was lower in PT than in FT. FE_β2 was higher in PT than in FT infants during the entire first month of life and FE_Na was higher in PT than in FT infants during the first week of life, suggesting a glomerular tubular imbalance at least at the level of the proximal tubule in PT infants. It is concluded that different stages of maturation will alter the preconditions for the renal adaptation to extrauterine life during at least the first month of life. Therefore special attention must be paid to the limited renal function in PT during their entire first month of life.     

RENAL COMPENSATORY HYPERTROPHY IN CHILDREN WITH UNILATERAL RENAL DISEASE

Abstract. Wilton, P., Aperia, A., Broberger, O. and Wikstad, I. (Departments of Pediatrics and Pediatric Radiology, Karolinska Institute, St. Göran's Children's Hospital, Stockholm, Sweden). Renal compensatory hypertrophy in children with unilateral renal disease. Acta Paediatr Scand, 69:83, 1980.—Kidney parenchymal size was estimated on urograms from 22 children with unilateral vesico-ureteral reflux (VUR), 14 children with bilateral VUR and seven children with unilateral heminephrectomy. In the bilateral VUR group, one kidney was roentgenologically normal and the other was growth-retarded. The GFR was estimated in 19 of the children. The age of the children was 3–17 years and all had a history of urinary tract infection. The size of the smaller kidney varied between 33–97% of normal. Children in the unilateral VUR group with a small kidney due to scarring and/or growth retardation showed a varying degree of compensatory hypertrophy in the contra-lateral kidney, which was proportional to the parenchymal reduction. This compensation was inhibited in the bilateral VUR group. There was a positive correlation between the GFR and kidney size