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Biomedical subjects

A D Goodman

Publications and source records attributed to A D Goodman.

At least 55 records · Page 3Linked to original sources
PubMed1977

Isolation of anaerobic bacteria from the root canal systems of necrotic teeth by the use of a transport solution.

The purpose of this study was to develop a clinically practical technique for isolating predominant anaerobic microorganisms from the root canal systems of intact necrotic teeth. Fifty-five consecutive teeth, all of which were necrotic, were sampled for this study. The technique developed involved a transport solution into which each sample was placed. At least one anaerobic bacterium was isolated from each case, with as many as four anaerobic bacteria being isolated from one case. Over half of the total number of organisms isolated were anaerobes, and almost half of these organisms were gram-negative. Whereas this technique has enabled the author to isolate and identify the same spectrum of predominant anaerobic bacteria as has been reported recently by others using the rigid VPI technique, the author suggests that the technique described here be utilized when the VPI technique cannot be performed.

Anaerobiosis↗
PubMed1977

Eikenella corrodens isolated in oral infections of dental origin.

Eikenella corrodens causes significant clinical infection more frequently than is suspected at the present time. The laboratory must be made aware of the organism and the techniques that are necessary to identify it. The clinician must be aware of the methods of isolating organisms in general. The use of a transport solution was shown to be a highly effective and clinically practical way of isolating those organisms present. The pathogenic potential of E. corrodens can no longer be doubted.

Adolescent↗
PubMed1977

Studies of the composition and radioreceptor activity of "big" and "little" human growth hormone.

Immunoreactive growth hormone (GH) from human pituitary and plasma contains "big" (BGH) and "little" (LGH) components. BGH itself consists of a "urea-labile" form and a "urea-stable" form (usBGH). In the present study we determined the amino acid composition of a BGH preparation containing both the urea-labile and urea-stable components and bound it to be indistinguishable from that of LGH. This finding, coupled with observations of others, suggests that urea-labile BGH is a simple LGH dimer and that usBGH is a disulfide dimer. We have prepared LGH, BGH, and usBGH from human pituitary GH, and studied their radioreceptor activity, in relation to their immunoreactivity, in plasma membrane systems from rabbit, rat and human liver and rabbit mammary gland. When 125I-LGH was used as the radioligand, LGH and usBGH caused parallel displacement, usBGH was 60-74% as active as LGH in the animal preparations, while in human liver the two forms were equally active. Three different BGH preparations studied in the animal systems were 26-33% as active as LGH. The receptor activity of these BGH preparations was greater than expected from their usBGH content, suggesting that urea-labile BGH also binds to the LGH receptor. When 125I-usBGH was employed as radioligand, we found that in the presence of 2,000 ng/ml of LGH, which caused maximal displacement of 125I-usBGH, the addition of 2 ng/ml of usBGH produced additional displacement. This suggested the presence of a receptor specific for usBGH. However, the phenomenon proved to be due to a contaminant in the usBGH preparations which decreased binding of 125I-usBGH. BGH containing a substantial fraction of usBGH, and "freeze-stable" BGH which is probably identical with usBGH, both failed to displace 125I-usBGH in the presence of 2,000 ng/ml LGH. These observations rule against the existence of a specific receptor for usBGH.

Amino Acids↗
PubMed1976

Effect of angiotensin II on cyclic guanosine monophosphate and cyclic adenosine monophosphate in human plasma.

Infusion of alpha-adrenergic catecholamines increases plasma cyclic guanosine monophosphate (pcGMP), raising the possibility that the pressor effect of these agents may be mediated by cyclic GMP. We infused pressor doses of angiotensin II in 10 studies in 8 normal subject and measured pcGMP and plasma cyclic adenosine monophosphate (pcAMP) by radioimmunoassay. After 120 minutes of infusion, mean pcGMP was 128 +/- 31% (SE) higher than baseline values (P less than 0.01) while pcAMP was increased 30 +/- 10% (P less than 0.05).

Angiotensin II↗
PubMed1975

Familial hypertension.

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Adrenal Hyperplasia, Congenital↗
PubMed1974

Studies on "big" growth hormone from human plasma and pituitary.

Most of the immunoreactive growth hormone (IRGH) in human plasma elutes from Sephadex G-75 as "little" GH (LGH), mol wt 22,000, but 14-39% elutes earlier ("big" GH, BGH). In saline extracts of human pituitary, 11-17% of IRGH eluted as BGH. On gel filtration of pituitary and plasma BGH in 8 M urea, 59-81% ran as LGH, but when the remaining BGH was refiltered in urea, all ran as BGH. Thus there is a "urea-stable" and a "urea-labile" form of BGH. SImilarly, freezing and thawing converted over half of pituitary and plasma BGH to LGH, but when the "freeze-stable" BGH was again frozen, thawed, and refiltered, almost all ran as BGH. Urea-stable BGH was not dissociated by freezing, and most of the freeze-stable BGH was stable in urea, so the two forms are very similar or identical. Since 8 M urea and freezing dissociate peptides linked by noncovalent bonds, probably the BGH that is dissociated by urea and freezing consists of LGH bound noncovalently to another moiety, while in stable BGH the LGH is bound to another molecule by covalent or unusually strong noncovalent linkage. On centrifugation, the sedimentation of urea-stable BGH was consistent with a mol wt about twice that of LGH. Trypsinization of urea-stable BGH converted 36-59% to LGH, suggesting that some BGH may be a "prohormone" of LGH. On retrypsinization of the BGH that was not converted to LGH, only 13-24% converted, suggesting that there may be two forms of urea-stable BGH which vary in their response to trypsin.

Acromegaly↗
PubMed1970

Relation of renal cortical gluconeogenesis, glutamate content, and production of ammonia.

Glutamate is an inhibitor of phosphate dependent glutaminase (PDG), and renal cortical glutamate is decreased in metabolic acidosis. It has been postulated previously that the rise in renal production of ammonia from glutamine in metabolic acidosis is due primarily to activation of cortical PDG as a consequence of the fall in glutamate. The decrease in cortical glutamate has been attributed to the increase in the capacity of cortex to convert glutamate to glucose in acidosis. In the present study, administration of ammonium chloride to rats in an amount inadequate to decrease cortical glutamate increased the capacity of cortex to produce ammonia from glutamine in vitro and increased cortical PDG. Similarly, cortex from potassium-depleted rats had an increased capacity to produce ammonia and an increase in PDG, but glutamate content was normal. The glutamate content of cortical slices incubated at pH 7.1 was decreased, and that at 7.7 was increased, compared to slices incubated at 7.4, yet ammonia production was the same at all three pH levels. These observations suggest that cortical glutamate concentration is not the major determinant of ammonia production. In potassium-depleted rats there was a 90% increase in the capacity of cortex to convert glutamate to glucose, yet cortical glutamate was not decreased. In vitro, calcium more than doubled conversion of glutamate to glucose by cortical slices without affecting the glutamate content of the slices, and theophylline suppressed conversion of glutamate to glucose yet decreased glutamate content. These observations indicate that the rate of cortical gluconeogenesis is not the sole determinant of cortical glutamate concentration. The increase in cortical gluconeogenesis in acidosis and potassium depletion probably is not the primary cause of the increase in ammonia production in these states, but the rise in gluconeogenesis may contribute importantly to the maintenance of increased ammoniagenesis by accelerating removal of the products of glutamine degradation.

Acid-Base Equilibrium↗