Preparation of midsagittal semithin Epon sections of the entire secretory ameloblast population in the maxillary rat incisor

Abstract – To study cytological changes in the migrating cell layer of the ameloblasts in the rat incisor with semithin Epon sections the ideal section plane would consequently be along the midsagittal plane of the incisor. However, the small dimensions and the complex three-dimensional structure of the apical part of the odontogenic organ covered by alveolar bone make it difficult to orientate and position sections in the midsagittal plane. Serial sectioning of the apical half of the maxillary incisor in the horizontal and sagittal planes clarified the relation of the midsagittal plane of the odontogenic organ to the alveolar bone, and the changes of the sectional profile of the odontogenic organ as a function of its position on the transverse axis of the incisor. From this information a method was designed whereby the two axes of the midagittal plane were marked directly on the block surface before sectioning, and the position of sections in the midsagittal zone of the ameloblasts standardized.     

Serum galactosylhydroxylysyl glucosyltransferase in acute myocardial infarction and during subsequent collagen scar formation

Changes in serum galactosylhydroxylysyl glucosyltransferase, an enzyme catalysing one of the intracellular post-translational modifications in collagen biosynthesis, were studied in twenty-four patients with acute myocardial infarction. The enzyme activity was monitored for 18 days from the onset of infarction, and at least a two-peaked pattern was observed. The first peak corresponded to the stage of acute myocardial injury, there being a highly significant correlation between the maximal values for serum glucosyltransferase and alpha-hydroxybutyrate dehydrogenase. An average decreasing in serum glucosyltransferase activity of 41%, was noted during the following 24 h. A new gradual rise in serum glucosyltransferase activity, interpreted as indicating myocardial collagen scar formation, was observed 5 days after the onset of infarction, when the serum enzyme activities indicating myocardial injury had already declined. The average daily values for serum glucosyltransferase between 6 and 18 days correlated highly significantly with the maximal value for serum alpha-hydroxybutyrate dehydrogenase, which serves as a relative estimate of the size of the original myocardial infarction area. The data further suggest that certain other factors including heart failure and/or various drug treatments may also affect the magnitude of this second peak.     

DISCREPANCY BETWEEN ACTH AND CORTISOL RESPONSES TO INSULIN INDUCED HYPOGLYCAEMIA

The purpose of this study was to assess the normal relationship between plasma ACTH and cortisol during insulin induced hypoglycaemia. Twenty-six healthy persons were studied. Peak plasma concentration and the amounts of ACTH and cortisol secreted during hypoglycaemia were compared. There was no significant correlation between the ACTH and cortisol values. The ACTH responses varied significantly more than those of cortisol. This probably signifies an over-capacity of ACTH secretion in comparison to the secretory capacity of the adrenal cortex.     

EFFECTS OF EXOGENOUS CATECHOLAMINES AND EXERCISE ON PLASMA MAGNESIUM CONCENTRATIONS

Catecholamines and physical exercise are known to influence the metabolism of several minerals in man, but the effects on magnesium (Mg) have been scarcely investigated. In the present study, infusion of adrenaline (5 micrograms/min for 30 min followed by 10 micrograms/min for 30 minutes) significantly reduced the plasma Mg levels in healthy males. This effect was abolished by simultaneous infusion of propranolol. Noradrenaline had no such effect. In order to stimulate endogenous catecholamine release healthy males carried out physical exercise in four different ways: ergometer bicycling at maximum load until exhaustion with and without oral beta-blockade, ergometer bicycling with stepwise increasing load until exhaustion, isokinetic maximal exercise with one leg, with blood sampling both from the venous effluent of the exercising leg and the opposite resting arm and long-term (60 min) steady state ergometer bicycling at approximately 65% of estimated maximum capacity. During short-term (less than 20 min) intense exercise (i.e. experiments 1-3) the plasma Mg concentrations were increased. This was probably due to a reduction of plasma volume and to an influx of Mg to the vascular pool. During long-term steady state exercise (experiment 4) the Mg levels were not significantly affected but decreased during the first hour of recovery. These results suggest that both the beta-adrenergic system and muscular activity by itself affect Mg homeostasis.     

PROLONGED LOW-INTENSITY EXERCISE RAISES THE SERUM PARATHYROID HORMONE LEVELS

Twelve healthy males performed 5 h exercise on a bicycle ergometer at a constant work load of approximately 50% of their maximum capacity. The serum concentrations of parathyroid hormone (PTH) increased after the first hour and were continuously elevated throughout the exercise period. The rise in PTH was 5-7% above pre-exercise levels, corresponding to 20-30% of the maximal increase obtained by the same assay during prolonged hypocalcaemia. The probable cause for the rise in PTH was that the plasma ionized calcium tended to be lowered during exercise. Since the total serum calcium concentrations were raised (by 3-5%) during exercise the reduction of the free, ionized, fraction was presumably largely due to increased complex-binding although an outward transport from plasma was not excluded. The serum concentrations of magnesium were gradually reduced during exercise while those of phosphate and potassium were raised throughout, probably as a result of leakage from the working muscle.     

Palmitate and stearate binding to human serum albumin

Multiple binding equilibria of two apparently insoluble ligands, palmitate and stearate, to defatted human serum albumin were studied in a 66 mM sodium phosphate buffer (pH 7.4) at 37 °C, by determination of dialytic exchange rates of ligands among identical equilibrium solutions. The experimental data were analysed by a computerised curve fitting procedure using equilibrium equations for multiple binding of ligands, containing relative binding constants, valid whether the ligands are truly insoluble or are slightly soluble and irrespective of aggregation in aqueous solution. A best-fit set of relative binding constants was found, and subsequently 30 sets of acceptable constants for each set of data in order to evaluate the variation. The data were first fitted by the relative Scatchard's equation, then by the relative, stoichiometric equation. Scatchard's equation is deduced on the presumption that cooperativity is absent while the stoichiometric equation is valid even when cooperativity is present. It was found with palmitate as well as with stearate that the two equations fitted the data equally well, and it was concluded that the observations were compatible with absence of cooperativity. The relative Scatchard binding constants were converted to relative, stoichiometric constants and it was found that the variations of the latter were slight. © Munksgaard 1997.     

Frequency of Hepatic Cysts in Adult Polycystic Kidney Disease

Abstract. The frequency of hepatic cysts in patients with adult polycystic kidney disease (APKD) is usually considered to average about 33%, but with great, and hitherto largely unexplained, variations between different studies. Sixty-six consecutive patients with APKD were all subjected to CT scanning of the liver and of the kidneys. In confirmation of one previous study, a clearcut correlation was found between age (=duration of disease) and the frequency of hepatic cysts. It was furthermore found that cysts in the liver, as opposed to cysts in the kidneys, continue to grow and appear de novo even after institution of renal replacement therapy.     

Excessive Hypercalcaemia and Mixed Connective Tissue Disease

ABSTRACT A 23-year-old female with extreme hypercalcaemia was treated with calcitonin, mitramycin and parathyroidectomy and normocalcaemia was achieved after 4 weeks. Nevertheless, the patient later died of cutaneous necrosis, impaired circulation and multiple organ failure. Serum immunoreactive parathyroid hormone was in the normal range and parathyroid tissue normal. Mixed connective tissue disease was diagnosed on the basis of high titers of antibody to extractable nuclear antigen, moderately elevated levels of antibody to nuclear antigen and only marginal elevation of anti-double standed DNA. The role of Cl. difficile toxin in the blood and an acinic cell tumour is unclear.