Pathogenicity of Ichthyophonus hoferi for laboratory-reared Pacific herring Clupea pallasi and its early appearance in wild Puget Sound herring.

Laboratory-reared pathogen-free Pacific herring were exposed to pure cultures of Ichthyophonus hoferi, and reproduced the disease seen in naturally infected fish--thus fulfilling Koch's Postulates. Pathogen-free herring used in this study were reared from artificially spawned eggs incubated in filtered, UV-sterilized seawater, eliminating the variables associated with multiple infections, which are common in wild herring. Wild free-ranging herring were captured monthly from June through October by dip net from 'herring balls' located in the northern Puget Sound. I. hoferi infections were identified in these fish soon after metamorphoses, about 4 mo post-hatch. The prevalence increased from 5 to 6% in 0-yr fish to 24% in 1-yr-old fish to 50 to 70% in fish over 2 yr old, with no associated increase in mortality. The route of natural transmission to wild herring was not determined, but carnivorous fish became infected and died when they were experimentally fed tissues infected with the organism. In vitro culture of tissues was the most sensitive method for identifying both clinical and subclinical infections.

Effect of 7.2% hypertonic saline/6% hetastarch on left ventricular contractility in anesthetized humans.

BACKGROUND: Although a positive inotropic effect of hypertonic saline has been demonstrated in isolated cardiac tissue as well as in animal preparations, no information exists about a possible positive inotropic action of hypertonic saline in humans. The aim of this investigation was to determine whether a clinically relevant positive inotropic effect can be demonstrated in humans. METHODS: Twenty-six patients without cardiovascular disease were randomized to receive 4 ml/kg of either 7.2% hypertonic saline/6% hetastarch or 6% hetastarch (control) at a rate of 1 ml.kg-1.min-1 while under general endotracheal anesthesia. Transesophageal echocardiography was used to evaluate left ventricular function. Arterial pressure, heart rate, and left ventricular end-systolic and end-diastolic diameter, area, and wall thickness were measured immediately before and after administration of either solution. Fractional area change, end-systolic wall stress, and the area under the end-systolic pressure-length relationship curve (ESPLRarea) were calculated. ESPLRarea was used to assess left ventricular contractility. RESULTS: Administration of hypertonic saline/hetastarch resulted in a significant decrease of mean arterial pressure and end-systolic wall stress from 77 +/- 14 (mean +/- SD) to 64 +/- 17 mmHg (P < 0.01) and from 52 +/- 14 to 32 +/- 11 10(3) dyne/cm2 (P > 0.01), respectively. End-diastolic area and fractional area change increased from 16.5 +/- 2.9 to 21.7 +/- 3.3 cm2 (P < 0.01) and from 0.53 +/- 0.07 to 0.70 +/- 0.06 (P < 0.01), respectively, whereas there was only a minor change of ESPLRarea from 38 +/- 13 to 44 +/- 13 mmHg.cm (P < 0.05). CONCLUSIONS: The apparent improvement of left ventricular systolic function in response to hypertonic saline/hetastarch is caused mainly by the combined effect of increased left ventricular preload and reduced left ventricular afterload. A possible positive inotropic action of hypertonic saline/hetastarch is not likely to be clinically relevant.

Interaction of Pseudomonas aeruginosa with A549 pneumocyte cells.

The interaction of Pseudomonas aeruginosa with a human lung pneumocyte cell line (A549) was studied. Wild-type strain PAK adhered efficiently to the A549 cells, while an isogenic mutant, carrying a mutation in the pilin structural gene, adhered at 10 to 20% of the wild-type levels. Another nonpiliated mutant of P. aeruginosa PAK, defective in the pleiotropic regulatory gene rpoN, did not adhere to A549 cells, suggesting the presence of a second, RpoN-controlled adhesin on the bacterial surface. Endocytosis of wild-type P. aeruginosa PAK by A549 cells was also demonstrated. A significant fraction of the internalized bacteria were recovered in a viable form after several hours of residence within the A549 cells. When examined by electron microscopy, intracellular bacteria were located in membranous vesicles, and no evidence of killing by lysosomal mechanisms was observed. These studies raise the possibility that during chronic respiratory tract infections in immunocompromised patients, P. aeruginosa may persist in intracellular compartments and therefore be protected from the defense mechanisms of the host.

Effect of psychosocial factors on success in a program of self-glucose monitoring.

We examined prospectively the relationship of psychosocial factors to glycemic control in a program of self-glucose monitoring (SGM). Measured intelligence (IQ), educational level, and socioeconomic status (assessed by the Two-Factor Index of Social Position) were determined in 25 patients who were followed during 6 months of self-glucose monitoring. Personality categories, reflecting degrees of psychological disturbance, were assigned using the Minnesota Multiphasic Personality Inventory (MMPI). None of the measured psychosocial variables correlated significantly with initial Hgb A1 values. In contrast, after 6 months of SGM, Hgb A1 levels correlated significantly with both socioeconomic status (r = 0.42, p less than 0.05) and educational levels (r = -0.42, p less than 0.05). Hemoglobin A1 levels also correlated significantly with the recorded frequency of SGM (r = -0.65, p less than 0.01), a measure of patient compliance. No significant correlation between IQ and Hgb A1 levels was seen, either initially or during follow-up. High A1 values differed significantly among groups classified by MMPI testing. Patients with severe psychological abnormalities had higher (p less than 0.05) mean Hgb A1 levels. We conclude that psychosocial factors, but not measured intelligence, have an important bearing on patient success in a program of SGM.

Inhibition of insulin degradation by insulin-like growth factors.

The effect of insulin-like growth factors (IGF 1 and IGF 2) on insulin degradation was studied with the use of a preparation of insulin protease from rat skeletal muscle. Insulin, IGF 1 and IGF 2 inhibited 125I-insulin degradation by this enzyme. IGF 2 was the most potent inhibitor and IGF 1 was the least potent. These results are similar to what has been reported previously for the insulin-degrading activity in the serum of a diabetic patient who was resistant to sc and im insulin. Insulin protease also degraded 125I-iodo IGF 1 and 125I-iodo IGF 2. 125I-iodo IGF 2 was degraded more rapidly than was 125I-iodo IGF 1. 125I-iodoinsulin was degraded more rapidly than 125I-iodo IGF 2. With all three peptides, immunoprecipitation was a more sensitive measure of degradation than was trichloroacetic acid precipitation. The results suggest that insulin protease may be responsible for the degradation of insulin-like growth factors as well as of insulin.

Comparison of two indices of glycemic control in diabetic subjects: glycosylated serum protein and hemoglobin.

Glycosylated serum protein (GSP) and glycosylated hemoglobin (GHb) were measured in 263 insulin-dependent and 41 non-insulin-dependent diabetic subjects. Both indices provided useful information in type II diabetes, but were extremely poor in judging control in type I diabetes. In both groups, there was poor correlation of the fasting serum glucose with either GSP or GHb. Only 4% of type I diabetic subjects had normal values for both GSP and GHb. Of subjects with elevated GSP, 98% had elevated GHb; 25% of subjects with elevated GHb values had normal values for GSP.

Non-enzymatically glycosylated serum protein in diabetes mellitus: an index of short-term glycaemia.

We measured non-enzymatically-glycosylated serum protein by a colorimetric assay in 107 diabetic and 82 control subjects. The mean level in diabetics was more than twice that in controls. Cross sectional and longitudinal studies in diabetic patients showed that glycosylated serum protein levels correlated with both fasting serum glucose and glycosylated haemoglobin levels. The correlation between glycosylated serum protein and fasting serum glucose was closer in Type 2 than in Type 1 diabetes. Treatment aimed at improving control in eight poorly controlled diabetic patients resulted in a 37% mean fall in glycosylated serum protein within one week, whereas glycosylated haemoglobin decreased only 8%. These studies confirm that non-enzymatic glycosylation of serum proteins is enhanced in diabetes. Measurement of glycosylated serum protein appears to provide an index of glycaemia over the preceding several days. It has the advantage of detecting improvements in glycaemic control much sooner than does glycosylated haemoglobin measurement.

Serum glycosidase activity in diabetes mellitus.

The activity of three glycosidic enzymes, B-glucuronidase, N-acetylglucosaminidase, and B-galactosidase were measured in plasma samples from 163 diabetic subjects and 72 normal controls. No age- or sex-based variation in concentration was noted in controls. Plasma activity of B-glucuronidase and N-acetylglucosaminidase in diabetics correlated directly with the overall level of glycemia as measured by HbA1c levels. B-galactosidase activity was consistently normal in diabetics. A significant age-based variation was noted in the diabetic group for B-glucuronidase and N-acetylglucosaminidase. Prior to age 12 B-glucuronidase and N-acetylglucosaminidase were normal in diabetics, but activity increased significantly after the age of 12, a change that appeared to coincide with the development of puberty.

Binding and degradation of semisynthetic tritiated insulin by IM-9 cultured human lymphocytes.

Insulin was tritiated by semisynthetic replacement of the amino-terminal phenylalanine of the B chain with tritiated phenylalanine. At 15 degrees C, (3H) insulin bound to high affinity receptors on IM-9 cultured human lymphocytes with an affinity constant of about 3 x 10(9) M-1, The Scatchard plot was curvilinear. At 37 degrees C, maximal binding occurred after about 15 min of incubation. Binding fell thereafter due to degradation of insulin by the extracellular fluid. The major degradation product after 120 min coeluted with insulin from Sephadex G50 and was precipitated by anti-insulin antibody but to a lesser degree than intact insulin. It had little or no biologic activity as assessed by binding to IM-9 lymphocytes. The cell-associated radioactivity was also eluted as a single peak on Sephadex G-50. In contrast to the degradation product, this material retained its ability to bind to insulin receptors. We deduce that this cell-associated material contains the entire A chain, most of the B chain, and is probably native insulin. These data show that insulin bound to IM-9 lymphocytes remains biologically intact.

Nonenzymatically glycosylated serum protein: spurious elevation due to free glucose in serum.

The presence of free glucose in serum was found to interfere with accurate measurement, by a colorimetric method, of nonenzymatically glycosylated serum proteins. A mean elevation to 241% of basal levels was observed in the serum of 11 nondiabetic subjects to which glucose, in a concentration of 300 mg/dl, had been added immediately before assay. After dialysis of serum samples to remove glucose, levels of nonenzymatically glycosylated serum proteins were 0.27 +/- 0.11 and 0.79 +/- 0.24 nmol 5-hydroxymethylfurfural/mg protein (mean +/- SD), respectively, in 57 nondiabetic and 62 type I diabetic subjects. Levels observed before dialysis of serum were approximately two to three times higher. These studies indicate that removal of free sugar from serum is necessary for accurate measurement of glycosylated protein by the colorimetric method, and this can be achieved by overnight dialysis of serum against normal saline.

Insulin receptor binding and degradation in IM-9 cultured human lymphocytes - importance of extracellular degradation.

Insulin degradation in IM-9 cultured human lymphocytes occurs extracellularly. In the presence of 0.1% bovine serum albumin, insulin degradation products are formed that are soluble in 5% trichloroacetic acid. In the presence of 5% bovine serum albumin, the major products of insulin degradation are insoluble in 5% trichloroacetic acid and have little or no biological activity. Inhibition of binding with Concanavalin A or antireceptor antibody does not affect the rate of insulin degradation.