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1.  Comparison of Three Culture Media for Isolation of Mycobacterium tuberculosis: a 6-Year Study 
Applied Microbiology  1973;26(6):880-883.
Among 2,648 specimens positive on culture for Mycobacterium tuberculosis over a 6-year period, 82% grew on Lowenstein-Jensen medium (LJ), 79% on American Trudeau Society (ATS), and 56% on Middlebrook 7H10 (7H10). When these commercial culture media were compared in regard to the number of acid-fast bacilli seen on the original smears, LJ cultures were found to have the highest isolation rates for each smear category, and 7H10 had the lowest rates. Comparing the media from the aspect of number of mycobacterial colonies produced, LJ and ATS had the highest average colony counts, followed by 7H10. These findings were relatively constant over the 6-year period. One possible reason for the low positive rate of 7H10 was the lack of CO2 enrichment.
PMCID: PMC379926  PMID: 4203334
2.  Biosynthesis of Proparathyroid Hormone and Parathyroid Hormone by Human Parathyroid Glands 
Journal of Clinical Investigation  1973;52(12):3089-3094.
Human parathyroid glands obtained at autopsy were incubated with [3H]leucine and [3H]lysine. After incubation, nonradioactive parathyroid tissue of either human or bovine origin was added. Radioactive parathyroid hormone and proparathyroid hormone were isolated from the gland and medium by organic solvent and salt fractionation, trichloroacetic acid precipitation, Sephadex G-100 gel filtration, and carboxymethyl cellulose column chromatography. The human hormonal peptides were identified in the ion-exchange column eluates by their relatively high levels of radioactivity, their elution positions, and their immunoreactivity to anti-PTH antiserum. The time-course of radioactive amino acid incorporation into these peptides and a brief incubation of the gland with radioactive amino acids, followed by various lengths of incubation with nonradioactive amino acids, indicated that a precursor-product relationship exists for the two peptides. An alternate method for isolation of the hormone and prohormone, which involves separation of peptides by urea-polyacrylamide gel electrophoresis, confirmed the identities of the human parathyroid hormone and proparathyroid hormone.
PMCID: PMC302584  PMID: 4750442
3.  tyrR, A Regulatory Gene of Tyrosine Biosynthesis in Salmonella typhimurium 
Journal of Bacteriology  1973;115(3):1094-1102.
4-Fluorophenylalanine-resistant mutants of Salmonella typhimurium were isolated in which tyrosine pathway enzymes were not repressed by l-tyrosine. The mutants produced elevated levels of 3-deoxy-d-arabinoheptulosonic acid 7-phosphate (DAHP) synthetase (tyr) and chorismate mutase T-prephenate dehydrogenase, and these enzymes as well as transaminase A were not repressed by high concentrations of tyrosine. Genetic analysis revealed that a mutation in a gene designated tyrR was responsible for the constitutivity of the tyrosine pathway enzymes in strains SG1, SG7, and SG9, and that tyrR was linked to pyrF. In strain SG1 a mutation had also occurred in aroF, the structural gene for DAHP synthetase (tyr), resulting in loss of sensitivity of this enzyme to end-product inhibition. There appeared to be no relationship between loss of feedback inhibition and loss of end-product repression, since derivative strains of SG1 that carried only the tyrR mutation behaved like the singly mutated tyrR strains, SG7 and SG9, in showing high constitutive levels of tyrosine-specific enzymes that were not repressed by tyrosine.
PMCID: PMC246358  PMID: 4147003
4.  A Regulatory Gene of Phenylalanine Biosynthesis (pheR) in Salmonella typhimurium 
Journal of Bacteriology  1973;115(1):121-128.
4-Fluorophenylalanine-resistant mutants of Salmonella typhimurium were isolated in which synthesis of chorismate mutase P-prephenate dehydratase (specified by pheA) was highly elevated. Transduction analysis showed that the mutation affecting pheA activity was not linked to pheA, and conjugation and merodiploid analysis indicated that it was in the 95- to 100-min region of the Salmonella chromosome. Evidence is presented for the hypothesis that the mutation responsible for constitutivity of chorismate mutase P-prephenate dehydratase occurred in pheR, a gene specifying a cytoplasmic product that affected pheA. pheR mutants were found to carry a second mutation, tyrO. The tyrO mutation acts cis to cause increased levels of the tyrosine biosynthetic enzymes 3-deoxy-d-arabinoheptulosonate 7-phosphate synthetase (tyr) and prephenate dehydrogenase, but it has no effect on regulation of pheA.
PMCID: PMC246221  PMID: 4577738
5.  Breech management with fetal blood sampling. 
British Medical Journal  1973;1(5853):613.
PMCID: PMC1589920  PMID: 4694415
6.  Fermentation Kinetics and Continuous Process of L-Asparaginase Production 
Applied Microbiology  1973;25(1):92-96.
For the purpose of obtaining L-asparaginase in quantities from Erwinia aroideae, cell growth and enzyme formation were investigated in both batch and continuous fermentation. Using yeast extract as a growth-limiting substrate, the relationship between specific growth rate and substrate concentration was found to fit the Monod equation. The optimum temperature for enzyme production was 24 C, although cell growth was higher at 28 C. The enzyme yield reached its maximum of 4 IU/ml during the negative acceleration growth phase which occurs just prior to stationary growth. Compared to batch fermentations, the continuous fermentation process gave a lower enzyme yield except when the fermentation was conducted at a dilution rate of 0.1 hr-1. The graphical method frequently used for prediction of continuous fermentation does not apply to L-asparaginase production by E. aroideae. The optimum temperature for enzyme production in continuous process was 24 C, which was the same as in batch process. Increasing the temperature from 24 to 28 C resulted in a 20% loss of enzyme yield.
PMCID: PMC380741  PMID: 4568894

Results 1-6 (6)