Restriction site and genetic map of Cucurbita pepo chloroplast DNA

A detailed restriction map of squash chloroplast DNA (cpDNA) was constructed with five restriction endonucleases, SalI, PvuII, BglI, SacII, and PstI. The cleavage sites were mapped by sequential digestion of cpDNA using low-gelling temperature agarose. The restriction map shows that squash cpDNA is an approximately 153 kilobase (kb) circle with a large inverted repeat sequence of 23.3 kb, separated by a large (83.7 kb) and a small (22.7 kb) single copy region. Genes for a number of chloroplast polypeptides were localized on the map by hybridizing the cpDNA restriction fragments to heterologous gene-specific probes from tobacco, pea, tomato, maize, and spinach chloroplasts. The gene locations and organization of squash cpDNA are highly conserved and similar to chloroplast genomes of tomato, pepper, and Ginkgo.

Pharmacokinetics of N-4-hydroxyphenyl-retinamide and the effect of its oral administration on plasma retinol concentrations in cancer patients

Concurrent with a phase-II trial of 4HPR in patients with various cancers, we studied the plasma pharmacokinetics of both 4HPR and its major metabolite 4MPR as well as the effect of 4HPR administration on plasma retinol concentrations using a simple, specific and sensitive HPLC procedure. Initial estimates of plasma pharmacokinetic parameters after oral administration of 4HPR (300 mg/day) [corrected] in 3 cancer patients were the following: 4HPR, t beta 1/2 = 13.7 hr, AUC = 3.49 micrograms.hr/ml, CL = 56.57 L/hr/m2; 4MPR, t beta 1/2 = 23.0 hr, AUC = 1.15 micrograms.hr/ml, CL = 239.29 L/hr/m2. We also found that oral administration of 4HPR resulted in a rapid, profound and significant reduction in plasma retinol concentrations. The mean plasma retinol concentrations for 9 patients decreased 60% from baseline to below 200 ng/ml within 1-2 weeks of 4HPR dosing initiation. In addition, there was a concurrent, significant reduction in plasma retinol-binding protein levels in these patients. The mechanism whereby 4HPR reduces plasma retinol levels in vivo has not been determined. The addition of 4HPR to pooled human plasma at 37 degrees C in vitro did not reduce endogenous retinol levels, suggesting no direct chemical interaction between these 2 retinoids.

The excretion of large vitamin C loads in young and elderly subjects: an ascorbic acid tolerance test

An ascorbic acid tolerance test is described for assessing vitamin C status. The test is simple to administer and suitable for elderly patients. It involves giving an oral load of 1 g ascorbic acid in water and then measuring urinary excretion of vitamin C over the next 6 h. The excretion pattern at dosing has been studied in ten young subjects. The result of the ascorbic acid tolerance test in these young subjects was significantly different after supplementation with 1 g ascorbic acid daily for 1 month. Two series of elderly patients were also studied with the ascorbic acid tolerance test. They had low initial plasma ascorbic acid levels and much less vitamin C was excreted in the urine after dosing. Seven of these elderly patients were then supplemented with 1 g ascorbic acid for 1 month. After supplementation the initial plasma levels and their response to the ascorbic acid tolerance test became similar to that seen in younger subjects.

Isozyme-specific enzyme inhibitors. 12. C- and N-methylmethionines as substrates and inhibitors of methionine adenosyltransferases of normal and hepatoma rat tissues

The 2-, 3-, and 4-mono-C-methyl derivatives of D,L-methionine (Met) have been resolved into the 10 possible enantiomeric forms having the configurations 2-Me-D, 2-Me-L, 3(alpha or beta)-Me-D, 3(alpha or beta)-Me-L, 4(alpha or beta)-Me-D, and 4(alpha or beta)-Me-L (the alpha designation was given to enantiomeric pairs that had higher Rf values on silica gel chromatograms than their diastereomeric counterparts). All compounds were weak, poorly selective inhibitors of the rat M-2 (normal tissue) and M-T (Novikoff ascitic hepatoma) variants of Met adenosyltransferase. Kinetic analysis of the three most effective showed them to be competitive inhibitors with respect to Met with both variants; the strongest inhibition (KM(Met)/Ki = 0.03) was that of M-T by 3 beta-Me-L-Met. The Me-Met enantiomers had low substrate efficiencies (Vmax/KM) in the range (0.5-2.2) X 10(-4) that of L-Met with M-2 (0.2-1.3) X 10(-3) with M-T among seven compounds studied. At a 4 mM level, seven of the enantiomers were converted to adenosylmethionine derivatives more rapidly by M-T than by M-2. Among these, 2-Me-L-Met, 3 alpha-Me-L-Met, 3 alpha-Me-D-Met, and 4 beta-Me-D-Met had little or no substrate activity with M-2. These differences in substrate specificity are potentially exploitable in the design of compounds with selective toxicity for rat tumor tissue. N-Me- and N-(n-Bu)-Met, and the Met analogue in which NH is substituted for S, were weak inhibitors of M-T and M-2 and showed no substrate activity at a level of 4 mM.

Proteolytic denaturation and methods of improving the stability of glucose isomerase preparations

Evidence is provided in support of proteolytic denaturation of free and immobilized preparations of glucose isomerase from a Bacillus species. A number of methods to improve the stability with respect to proteolysis have been tested and their advantages as well as shortcomings are discussed. These methods include hollow-fiber treatment, gel permeation, thermal treatment, and addition of protease inhibitors. The half-life of the free and the cellulose acetate fiber-entrapped preparations of glucose isomerase can be significantly improved. For example, the hollow-fiber treatment can improve the half-life by an order of magnitude.

Concurrent cutaneous and hepatic hemangiomata in infancy: report of a case and a review of the literature

Fifty-eight cases of concurrent cutaneous and hepatic hemangiomatosis in infants have been reported in the world literature. A fifty-ninth case is herewith reported and the literature is reviewed. Untreated cases have a mortality rate of 81%, whereas the mortality of treated cases is 29%. The main cause of death appears to be the consequence of arteriovenous shunting in the liver. Early and aggressive treatment by prednisone, radiotherapy to the liver, partial resection of liver, and ligation of the hepatic artery, each alone or in combinations, have been effective.