Enhancement of α-methylglucoside efflux by respiration in respiratory mutants of Escherichia coli K-12

The rate of α-methylglucoside efflux from wild-type cells of Escherichia coli K-12 is enhanced by different substrates, as long as they are readily respired. A similar enhancement takes place in strains with impaired oxidative phosphorylation (unc mutants), regardless of their being able (strains AN120, N₁₄₄, and AN382) or unable (strain NR70) to energize the membrane through respiratory electron flow. The uncouplers carbonylcyanide-m-chlorophenylhydrazone and tetrachlorosalicylanilide do not diminish the efflux acceleration in wild-type strains or unc mutants. However, the stimulation of α-methylglucoside efflux does not occur in the mutant AN59 which cannot perform a normal respiratory electron transport due to a defective synthesis of ubiquinone. The failure to stimulate the efflux is observed with succinate, which is a typical substrate of respiration, as well as with substrates which can yield ATP both at respiratory and substrate levels such as gluconate or glycerol. Moreover, potassium cyanide nullifies the acceleration of α-methylglucoside efflux caused in any type of strain and by any substrate. These results show that neither ATP nor an energized state of the membrane appears to be needed for respiration to accelerate α-methylglucoside release from E. coli cells, and question the existence of any energy-requiring reaction for αMG exit, previously proposed by other authors.     

The effect of S-adenosyl-L-methionine (SAM) on membrane permeability in the perfused rat liver

S-adenosilmethionine is present in most human tissues and is an important factor for transmethylation, transulphuration and aminopropylation reactions. The compound improves the biological, morphological and histochemical aspects of rat liver following CCl4 intossication. At the same time has been successfully used during chronic liver disease in man. With the aim to better clarify the action mechanism of SAMe some aspects concerning its effects on cell permeability in rat liver, by using the perfusion technique, have been investigated. In particular the capacity of this compound to prevent the enzymatic loss (GPT and GOT) during liver perfusion has been studied. 30 perfusions without SAMe, as control, and 6 by infusing 2 mg of compound during the perfusion time have been accomplished. Varing the perfusion time from 0 to 120 min it has been observed that at any time the presence of the SAMe reduced by about 50% the loss of GOT. Similarly the activity of GPT ranging from 2 to 6 mU/ml indicate that no appreciable enzyme output occurs in presence of SAMe.     

Sterols from three Lactarius species

The sterol composition of three fungi was determined. Ergosterol is the major sterol, accompanied by other closely related sterols.     

Superficial mycoses in Italy

A total of 1244 cases suspected of superficial mycoses were analysed in a period of 12 months in Italy. Dermatophytoses were found in 62.4%; the other common disease was Pityriasis versicolor (44.1%). The predominant speciesEpidermophyton floccosum (34,2%) was strickingly high in relation to other statistics; this species was commonest in tinea cruris. Among the other dermatophytesM. canis was predominant (31.3%) commonest in tinea corporis, followed byT. mentagrophytes (17,8%) andT. rubrum (10,3%). A high rate of yeasts was found in tinea manum (81.6%) and tinea pedis (47.7%).     

Experiences from the accident of Seveso

Provisional data on selected sanitary events which took place at Seveso after July 10 1976 are reported. 187 cases of chloracne, mostly in children, were detected, 50 just after the accident, the others within a year. Most polluted area (zone A) provided almost all "early" and most severe cases, but the territorial distribution of chloracne prevalence rates showed some inconsistencies with the soil TCDD pollution map; interpretations for such findings are discussed. Thirty-eight birth defects were detected in 1977 (none in zones A and B), more than in previous years, but still less than expected in a well controlled "normal" population: no clustering around a given type was observed. Spontaneous abortions, evaluated both as abortion rates and as pregnancy loss rates, showed scattered and statistically non-significant variations, inconsistent with the pollution map. No differences in birth and death rates compared to surrounding areas were observed. Data on ad hoc cytogenetic, neurological and immunological surveys are commented. Limitations of the presently available data are discussed and further research lines are anticipated.     

Analysis and classification of vegetation based on family composition

Plant Ecology - The distributions of 54 plant families in 105 samples were studied to determine their indicator value in the vegetation of the Pacific Northwest. Families may be characteristic of...     

The differential effects of PGE on the immune response in normal and immunosuppressed mice

The effect of 16,16-dimethyl-PGE₂-methyl ester (di-M-PGE₂) on humoral and cellular immunoresponsiveness has been compared in normal mice and in mice immunosuppressed by splenectomy and thymectomy plus antithymocyte serum (ATS). Splenectomy resulted in immunosuppression manifested by augmentation of B-16 melanoma growth; this stimulatory effect was reversed by di-M-PGE₂. In animals immunosuppressed by thymectomy plus ATS, di-M-PGE₂ augmented the humoral and cellular immune responses; this was manifested by slowing of the growth of B-16 melanoma and by stimulating the number of plaque-forming cells, hemagglutinin titers, and delayed-hypersensitivity reactions to sheep erythrocytes. In contrast, in normal (nonthymectomized) mice, di-M-PGE₂ was mildly immunosuppressive. Finally, adriamycin-immunosuppressed normal mice and this suppression were reversed by the addition of di-M-PGE₂ to the treatment regimen.     

Inhibition of human seminal fluid and Leishmania donovani phosphatases by molybdate heteropolyanions

Inhibition of a tartrate-resistant acid phosphatase (ACP) from Leishmania donovani and the tartrate-sensitive ACP from human seminal fluid (prostatic ACP) was examined using a series of 13 molybdate-containing heteropolyanions. The heteropolyanions were divided into four groups based on the number of molybdenum atoms they contain: Group I, Mo4; Group II, Mo6-8; Group III, Mo12; Group IV, Mo18. Two of the four groups, those consisting of compounds that contain either an Mo4 unit or an Mo18 unit with a heteroatom in the central cavity, were potent inhibitors and exhibited the highest degree of selectivity against the leishmanial and seminal fluid ACPs. The inhibition of prostatic ACP by complex E2 could be completely reversed by dialysis. Little inhibition of the acid phosphatase, beta-glucuronidase, or alpha-mannosidase from human spleen was observed with complexes B' and E2. For the seminal fluid phosphatase, the Ki values obtained with arsenate and vanadate depended markedly on pH, suggesting that, unlike most other phosphatases, the conformation of the inhibitor binding site on human seminal fluid ACP is pH-dependent. Results of competition experiments performed with various inhibitor pairs indicated that complex D2 binds to the active site of prostatic ACP while complex M binds at some site on the enzyme that affects the active site. Binding of complex M also modifies the affinity of the enzyme for other inhibitors such as vanadate. The potency of several heteropolyanion complexes and their selective inhibition of pathophysiologically significant acid phosphatases indicate that these compounds may have value as tools for study of the structure and function of this class of enzyme and perhaps in the therapy of human disease.