Minimal tissue concentrations of glutamate required to produce necrosis of hypothalamic neurons in newborn mice

Groups of 4-day-old Cox Swiss albino mice were injected once subcutaneously with monosodium glutamate at several doses between 0.2 and 0.5 mg/g body weight. Glutamate, at a dose of 0.35 mg/g, produced neuronal necrosis of a very limited nature in only 60% of the animals and was defined as the minimal effective neurotoxic dose in the 4-day-old mouse. Neuronal loss was not detected in any animals treated with less than 0.35% mg/g of the amino acid whereas lesions became more extensive as the dose was increased to 0.5 mg/g. Glutamate was measured in the arcuate nucleus and plasma 0, 15, 30, 60 and 90 min after injection. These data indicated that duration of glutamate accumulation in the arcuate nucleus may be as important a variable in producing neuronal degeneration in the hypothalamus as concentration of the amino acid in that nucleus.

Evaluation of student performance in the four-year study of expanded functions for dental hygienists at the University of Iowa

A comparison was made of the quality of selected operative and periodontal procedures completed by expanded-function dental hygiene and senior dental students. Each student group included 48 students selected from all academic quartiles of their respective classes. The evaluated operative procedures included a Class II preparation and amalgam restoration and a Class III preparation and composite restoration. Both operative procedures were completed twice, once on a patient and once on a Dentoform. The periodontal procedures were completed on patients and included a periodontal examination, a periodontal treatment plan, and one quadrant of root planing and soft tissue curettage. Three examiners independently rated each student's performance in an examiner-blind situation. Examiners judged numerous criteria for each procedure as satisfactory or unsatisfactory. In addition, an overall rating of excellent, clinically acceptable, or unacceptable was given to each procedure. Comparisons between student groups of the time required to complete procedures showed that dental students completed cavity preparations of all operative procedures and quadrants of root planing and curettage in significantly less time than did dental hygiene students. For restorations, periodontal examinations, and treatment plans, there was no significant difference between student groups in the time required to complete procedures. In general, the results of the study showed that the dental hygiene students were able to perform selected operative and periodontal procedures at a comparable level to that of senior dental students.

"Pseudostone" of the gallbladder. Ultrasound findings and case report

The ultrasonic criteria for the diagnosis of gallbladder calculi are: (1) echo-dense structures which disturb the smooth contour of the posterior border of the gallbladder; (2) sonic shadowing, and (3) echoes from within the gallbladder. Diagnostic confidence increases greatly in cases in which internal echoes, contour irregularities, and sonic shadows have occurred simultaneously. A case is presented in which all three criteria are fulfilled, but which represents an artifact, i.e., "pseudostone." This was confirmed by varying the patient's respiration and showing that the "pseudostone" represented echoes from a loop of bowel which produced a significant impression on the posterior wall of the gallbladder during deep inspiration. The absence of cholelithiasis was confirmed by oral cholecystography.

Cleavage of adenosine 5'-monophosphate during uptake by Streptomyces griseus

Unlabeled adenine brought about a (delayed) decrease in radioactivity that had been taken up by phosphate-limited resting cells of Streptomyces griseus from [14C]adenine-labeled adenosine 5'-monophosphate (AMP). Inorganic phosphate, on the other hand, stimulated adenine uptake from AMP, presumably by activating an energy-dependent active transport mechanism. Unlabeled phosphate rapidly diluted the uptake of radioactivity from [32P]AMP. Adenine inhibited uptake of [32P]AMP but not that of [32P]orthophosphate; adenine is thought to act by inhibiting the cleavage of AMP. The uptake of 32P and 14C from double-labeled AMP showed marked differences; 32P was taken up much faster into both cells and nucleic acids. These data indicate that uptake of AMP components takes place after extracellular dephosphorylation of the nucleotide.

Effect of exogenous nucleotides on the candicidin fermentation

Addition of cyclic-AMP (c-AMP) to Streptomyces griseus fermentations inhibited candicidin formation. In a phosphate-free resting cell system, c-AMP inhibited net candicidin formation and incorporation of labeled propionate and p-aminobenzoic acid into the antibiotic but did not inhibit protein synthesis. All nucleotides tested, regardless of the position of the phosphate ester, were effective inhibitors; nucleosides and free bases were not. Inhibition occurred whether the nucleotide was added early or late. The results indicate that inhibition of antibiotic formation by exogenous nucleotides, including cyclic nucleotides, is similar to the effect produced by inorganic phosphate.

Postpartum acute renal failure: possible role for endarterial urokinase

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Hemoperfusion through albumin-conjugated agarose gel for the treatment of neonatal jaundice in premature rhesus monkeys

Hemoperfusion through albumin-conjugated agarose gel (AAG) effectively removes bilirubin (BR) and other albumin-bound materials from whole blood or plasma. We have used this technique to treat neonatal jaundice in premature rhesus monkeys with a specially designated apparatus which permits continuous perfusion through one of four columns arranged in parallel while the others are sequentially washed with saline and regenerated with ethanol. Less than 15 per cent of the animal's blood volume is required in the extracorporeal circuit at any time. Results indicate that (1) compared with five control monkeys which had a peak BR concentration ([BR]) averaging approximately 4 mg./100 ml., six experimental monkeys showed a significant (p less than 0.01) reduction, averaging 60 per cent, in [BR] after each of two perfusions at approximately 20 and 26 hours of age; (2) AAG hemoperfusion was even more effective in lowering [BR] in monkeys with higher preperfusion concentrations produced by BR infusion (average reduction = 68 and 87 per cent at preperfusion concentrations of 11.9 and 24.2 mg./100 ml., respectively); and (3) overall, BR eluted from the column averaged 93 per cent of the estimated preperfusion plasma BR pool. Unlike previous studies in rats, perfused monkeys showed significant platelet losses, although it was possible to prevent these losses by the use of "regional citrate" during perfusion. These studies suggest that AAG hemoperfusion is effective in the treatment of neonatal jaundice, although potential problems such as sterility and platelet loss need further evaluation before it can be considered for human use.

The use of calcium chelating agents and prostaglandin E to eliminate platelet and white blood cell losses resulting from hemoperfusion through uncoated charcoal, albumin-agarose gel, and neutral and cation exchange resins

Hemoperfusion through adsorbents such as charcoal, cation exchange (e.g., AG 50W-X8) and uncharged (e.g., XAD-2) resins, and albumin-agarose gel (AAG) has been proposed for use in patients with hepatic failure. However, the loss of white blood cells and, particularly, platelets caused by each of these adsorbents remains a major deterrent to their clinical use. In vitro studies demonstrate that addition of citrate, ethylenediamine tetraacetate (EDTA), or oxalate to heparinized human blood eliminated this loss of formed blood elements during hemoperfusion. The improvement in postperfusion platelet counts (per cent of preperfusion values) produced by citrate were XAD-2, 13 leads to 95 per cent; AG 50W-X8, 10 leads to 94 per cent; AAG, 17 leads to 94 per cent; and charcoal, 44 leads to 96 per cent. Prostaglandin E1 in high doses (5 mug/ml.) markedly reduced platelet losses. Lower doses were less uniformly effective. Three young rhesus monkeys were hemoperfused for 160 minutes with columns containing AAG, XAD-2, and charcoal. During the first 80 minutes, citrate and calcium were infused into the column inflow and outflow lines respectively. For all three adsorbents, average platelet counts in the monkeys (115 per cent) and column effluent (95 per cent) were unchanged from preperfusion control values during the first 80 minutes but fell promptly to 13 and 7 per cent, respectively, after the citrate infusion was stopped. Each of the monkeys tolerated the procedure without ill effects. Use of a system analogous to that described here may facilitate clinical application of the technique of hemoperfusion through a variety of adsorbents.

Rapid incorporation of precursors into candicidin by resting cells of Streptomyces griseus

Labeled acetate, propionate and p-aminobenzoic acid were efficiently incorporated into candicidin by phosphate-limited resting cells of Streptomyces griseus. The efficiency of incorporation in short-term experiments using phosphate-limited resting cells was similar to that achieved previously in long-term experiments using growing cells. (2-14C)Propionate was more efficiently incorpoated than (1-14C)propionate, (U-14C)propionate, or (U-14C)-acetate. p-Aminobenzoic acid incorporation is linear over a 10-hour period while those of acetate or propionate reach a constant level after approximately 4 hours of incubation. Double-labeled candicidin of high specific activity was prepared by supplementing the resting cell system with (3H)acetate and (14C)p-aminobenzoic acid.

Vinyl chloride-associated liver disease

Although polyvinyl chloride has been produced from vinyl chlride monomer for more than 40 years, recognition of toxicity among vinyl chloride polymerization workers is more recent. In the mid 1960s, workers involved in cleaning polymerization tanks were found to have acro-osteolysis. In 1974, the same population of workers was found to be at risk for an unusual type of hepatic fibrosis and angiosarcoma of the liver. We describe two cases of vinyl chloride-associated liver injury, one of hepatic fibrosis and one of angiosarcoma. Histologic features of these lesions are similar to the hepatic fibrosis and angiosarcomas resulting from chronic exposure to inorganic arsenicals. Preliminary studies suggest that the toxicity of vinyl chloride may result from formation, during high-dose exposure, of active metabolites by mixed function oxidases of the liver. Epidemiologic studies indicate an increased incidence not only of liver disease, but also of cancers of the brain, lung, and possibly other organs.

Abnormal hepatic transport of indocyanine green in Gilbert's syndrome

The plasma fractional disappearance rate of indocyanine green (kICG, min-1) and the absolute hepatic ICG removal rate (VICG, mg per kg per min) were determined in 26 patients with Gilbert's syndrome (GS) and 19 normal control volunteers following intravenous administration of doses of 0.5, 2.0, 3.5, and 5.0 mg per kg of dye. The diagnosis of GS was based on studies of radiobilirubin kinetics in all cases and liver biopsy in 22 cases. The patients were further classified into 3 subgroups, based on patterns of sulfobromophthalein (BSP) kinetics, as follows: GS I (15 patients) had normal BSP metabolism; GS II (5 patients) had a defect in BSP metabolism beyond the stage of initial hepatic uptake; and GS III (6 patients) had a defect in the initial hepatic uptake of BSP (Gastroenterology 63:472-481, 1972). Both kICG and VICG were significantly reduced, compared to normal controls, in the GS III group with defective BSP uptake, but did not differ significantly from normal in the GS I and GS II groups. Michaelis-Menten analysis of the data indicated that VMAX for ICG uptake in the GS III group (1.2 +/- 0.6 mg per min per kg) was significantly reduced compared to the previously established normal value of 3.6 +/- 0.6 mg per min per kg; (P less than 0.01). For the total population of 26 patients with Gilbets' syndrome, there was a highly significant correlation (r= 0.77, P less than 0.01) between kICG and lambda21BSP, the fractional hepatic uptake rate for BSP. These studies confirm previous work indicating that patients with Gilbert's syndrome constitute a heterogeneous population with regard to defects in hepatic organic anion transport, some of the defects not being attributable to glucuronyl transferese deficiency. Future studies of Gilbert's syndrome must take into account the existence of these subgroups, since they may have different underlying pathogenetic mechanisms.

Specific inhibition of candicidin biosynthesis by the lipogenic inhibitor cerulenin

Cerulenin, an inhibitor of fatty acid synthesis, inhibits specifically the biosynthesis of the polyene macrolide candicidin by resting cells of Streptomyces. 50% inhibition was achieved with a cerulenin concentration of 1.5 mug/ml. Cells in which candicidin synthesis was inhibited for 10 h remained capable of candicidin synthesis after removal of the inhibitor. Cerulenin inhibits specifically the incorporation of [14C] propionate into candicidin but does not affect total protein or RNA synthesis. The uptake of [14C] propionate was not inhibited under conditions which totally prevented the incorporation of propionate into candicidin. Incorporation of p-amino[14C] benzoic acid NH2 [14C] BzO- into the aromatic moiety of candicidin was also inhibited by cerulenin. The inhibitory action of cerulenin was not reversed by exogenous fatty acids. Since cerulenin is known to block the condensation of malonyl-CoA subunits in the formation of fatty acids, it is concluded that the polyene macrolide candicidin is synthesized via the polyketide pathway by condensation steps similar to those occurring in fatty acid biosynthesis.

Candihexin polyene macrolide complex: physicochemical characterization and antifungal activities of the single components

The candihexin complex produced by a natural mutant of Streptomyces viridoflavus has been resolved into eight components. At least six of them, having hexaene chromophores, can be separated directly by thin-layer chromatography. The four major components, candihexins A, B, E, and F, account for about 90% of the total complex. They have been isolated and purified to homogeneity. All the major components were found to have macrolide lactone rings with all-trans hexaene chromophores. Candihexins A and B have compositions and molecular weights similar to candidin, the heptaene polyene macrolide produced by the parent S. viridoflavus, whereas candihexins E and F show smaller molecular weights and rather different elementary compositions. Candihexins A and B yield the amino sugar mycosamine upon hydrolysis, but no sugar was found in hydrolysates of candihexins E and F. Candihexins A and B have high antifungal activity against yeasts and filamentous fungi. The amino sugar-lacking candihexins E and F show no antifungal activity at levels of 100 mug/ml.

Unconjugated hyperbilirubinemia. Physiologic evaluation and experimental approaches to therapy

The plasma concentration of unconjugated bilirubin is determined by the rate at which newly synthesized bilirubin enters the plasma (bilirubin turnover) and the rate of irreversible bilirubin removal by the liver (hepatic bilirubin clearance). Measurement of each of these variables by kinetic studies with radiolabeled bilirubin permits a precise classification of cases of unconjugated hyperbilirubinemia into those due to increased bilirubin turnover (for example, hemolysis), those due to decreased bilirubin clearance (for example, Gilbert's syndrome), and those in which both mechanisms operate. The ability to quantitate hepatic bilirubin clearance makes it possible to detect gilbert's syndrome even in the presence of concomitant hemolysis. Of the hereditary disorders of bilirubin metabolism, Gilbert's syndrome is common but innocuous, whereas Crigler-Najjar syndrome is rare but devastating. An unusual case of Crigler-Najjar syndrome is described in which bilirubin encephalopathy developed at age 10. Various modalities used in an attempt to reduce her plasma bilirubin concentration by either increasing bilirubin clearance or reducing bilirubin turnover are described.

Health and society in Amazonian Peru

During his work in a jungle hospital of the Amazonian part of Peru, the author was able to study the health care delivery system in the area. He was impressed by its inadequacy, which seemed to be due less to medical, technological, and manpower deficiencies than to social and economic factors. An attempt is made to identify and classify these constraints. A systems view of the health care insufficiencies is outlined, showing how some barriers prevent the patient from making contact with the health system (input level), how others interfere with its working (processor level), while others limit the efficiency of its actions (output level). Finally, some measures for its improvement are considered.

Sequence of biosynthesis of the components of the polyene macrolides candidin and candihexin: macrolide aglycones as intracellular components

A sequential formation of the single components of the polyene macrolide candidin complex (heptaene) has been found. In addition to the three components occurring in the candidin complex at the end of the fermentation, two other "early" all-trans heptaene components have been characterized. They exist only during the phase of active biosynthesis of candidin. Two of the components of the polyene macrolide candihexin complex (hexaene) that have been described as lacking amino sugar were the only intracellular (mycelium-associated) components observed under conditions in which no extracellular polyene remained attached to the producing cell. The results indicate that glycosylation of the macrolide ring takes place during the secretion process.

Quantitative thin-layer spectrodensitometric determination of the components of polyene macrolide antibiotice complexes

A direct spectrodensitometric method for quantitating the components of polyene macrolide complexes after separation by thin-layer chromatography is described. Resolution of the components of the candidin and candihexin complexes was good up to 2.5 and 10 mu-g/spot, respectively. The peak areas were linear with the amount spotted up to the same levels. Maximum peak areas for the components of the candidin and candihexin complexes were obtained using light wavelengths of 360 and 340 nm, respectively. Spotting errors rather than instrumental parameters were responsible for the variance of repeated determinations. Minimal relative standard deviation values were found at intermediate concentration levels in the linear range.

Attempted suicide with a pesticide mixture

An attemped suicide with a pesticide mixture containing pentachlorophenol, benzene hexachloride, dieldrin, metaldehyde phenoxyacetate esters, paraquat, diquat and petroleum distillates, is reported. The prognosis initially seemed hopeless, but the patient was treated successfully by intensive care with early respiratory assistance.

Chemical changes in the cell walls of conidia of Penicillium notatum during germination

Conidial and mycelial cell walls of Penicillium notatum were found to be chemically different, the main differences being in the distribution of amino acids, neutral sugars, and amino sugars. The amino acid content was higher in conidial than in hyphal walls but individual amino acids found in spore and mycelial walls were essentially the same, except for basic amino acids (histidine, arginine, and lysine) of which only traces were present in mycelial walls.Four neutral sugars (glucose, galactose, mannose, and rhamnose) were detected in walls of resting spores, but rhamnose was absent at other stages of germination. Galactose was the most abundant sugar in walls of resting spores, while glucose was the main component of hyphal walls. Only one hexosamine (glucosamine) was found in walls of resting and swollen spores but galactosamine was present in walls of germinating spores and mycelium. The content of both amino sugars greatly increased during germination.

Ultrastructural changes in the conidia of Penicillium notatum during germination

To study the changes in the cell wall of Penicillium notatum during germination, thin sections of resting, swollen, and germinating spores, and mycelium were compared with thin sections of the isolated cell walls. In the cell wall of resting spores four distinct layers were found. The outermost layer of the cell wall of resting spores was released during swelling and the two inner layers were extended to form the cell wall of the germ tube. The cell wall of young germ tubes had only two layers but a new electron-dense layer was formed later on the outside. Mycelial cell walls which appeared thinner than those of conidia showed three distinct layers. Large mitochondria that divide during germination were present in both resting and swollen spores. Two different types of vacuoles were found, both of which decreased in size and in number during germination. Endoplasmic reticulum was almost absent in resting spores but increased substantially during swelling.