PubMed Health⌕ Search

Biomedical subjects

D Berkowitz

Publications and source records attributed to D Berkowitz.

29 records · Page 2Linked to original sources
PubMed1971

D-Mannitol utilization in Salmonella typhimurium.

A biochemical and genetic analysis of d-mannitol metabolism in Salmonella typhimurium indicates that d-mannitol is phosphorylated by the phosphoenolpyruvate-dependent phosphotransferase system. d-Mannitol-1-phosphate is converted to d-fructose-6-phosphate by mannitol-1-phosphate dehydrogenase. Two classes of mannitol mutants are described. Both map at about 115 min on the Salmonella chromosome. Mutants missing mannitol-1-phosphate dehydrogenase activity are mannitol sensitive; i.e., either growth is inhibited or the cells are lysed in the presence of mannitol. In a strain missing adenyl cyclase activity, the mannitol genes require exogenous cyclic adenosine-3',5'-monophosphate for expression.

Adenine Nucleotides↗
PubMed1969

Radiation sterilization of prototype military foods. 3. Pork loin.

Ten lots of pork loin, packed in cans, were inoculated with approximately 10(6)Clostridium botulinum spores per can. Each lot was seeded with a different strain; five type A and five type B strains were used. The pack comprised 5,690 cans, including controls, and contained about 10(9) spores per dose. The cans were irradiated with Co(60) in the range of 0 to 5.0 Mrad (0.5 Mrad increments) at 5 to 25 C, incubated for 6 months at 30 C, and examined for swelling, toxicity, and recoverable C. botulinum. The minimal experimental sterilizing dose (ESD) based on nonswollen, nontoxic, but nonsterile end points was 2.5 < ESD </= 3.0 Mrad, and based on non-spoiled sterile cans was 3.5 < ESD </= 4.0 Mrad. The theoretical minimal radiation dose (MRD), the 12D equivalent, varied with the method of computation: 4.74, 4.33 +/- 0.17, and 4.19 to 4.99 Mrad were obtained by the Weibull, Spearman-Karber, and Schmidt-Nank techniques, respectively. Calculation of D and MRD values by the conventional Schmidt-Nank method produced increasing values with rising dosage; this finding was compared with the data derived by the other two methods of calculation. Suggestions for estimating the MRD of a prototype radiation process are offered.

Animals↗
PubMed1968

Procedure for identifying nonsense mutations.

A method has been devised for the rapid identification of nonsense mutations (UAG, UAA, UGA codons) in Salmonella. The mutations to be tested are reverted, and the revertants are replica-printed onto lactose plates spread with lawns of tester strains. These tester strains contain F' lac episomes with nonsense mutations in the episomal Z gene. The revertants are infected with the episome from the tester strain lawn. Because S. typhimurium is unable to ferment lactose, only those revertants which have nonsense suppressors are able to grow on lactose. If colonies appear on the lactose plate, it may be concluded that the original strain carries a nonsense mutation, since nonsense suppressors suppress the mutant phenotype.

Bacteriological Techniques↗
PubMed1967

Radiation sterilization of prototype military foods. II. Cured ham.

Ten lots of diced cured ham, packed in cans, were inoculated with approximately 10(6)Clostridium botulinum spores per can. Each lot was seeded with a different strain (five type A and five type B strains). All cans were irradiated to various dose levels with Co(60). Evidence provided by swelling, toxicity, and recoverable C. botulinum with 6,350 cans demonstrated that: (i) 4.5 Mrad was more than adequate as a sterilization dose; (ii) the minimal experimental sterilizing dose (ESD) based on nonswollen nontoxic endpoints was 2.0 < ESD </= 2.5 Mrad, and based on non-spoiled sterile cans was 3.0 < ESD </= 3.5 Mrad (the latter was supported by the computed theoretical 12D dose); (iii) D values calculated from botulinal survival data indicated that, as a group, the type A strains were more radioresistant than type B strains; strains 12885A and 41B, with respective D values of 0.242 and 0.175, represented the most resistant of each type; (iv) swollen cans did not always contain toxin, nor were toxic cans always swollen; (v) viable C. botulinum can exist for 6 months at 30 C without producing visible or toxic spoilage at doses of 3.0 Mrad and lower, including, in some instances, 0.0 Mrad; and (vi) a phenomenon similar to heat activation of spores occurred at sublethal radiation doses.

Animals↗
PubMedDate not supplied

Presumed immune thrombocytopenia and carcinoma: report of three cases and review of the literature.

Three patients presenting in a one-year period with coexisting carcinoma and presumed immune thrombocytopenia are the subject of this report. Review of the literature disclosed a paucity of previous reports of this association. Possible pathogenic mechanisms resulting in this association are discussed. All three patients responded to corticosteroids in usual doses used in treatment of chronic idiopathic thrombocytopenic purpura. The association of carcinoma with immune thrombocytopenia may be more common than has been previously appreciated.

Adrenal Cortex Hormones↗