Inhibition of tyrosinase by indole compounds and reaction products. Protection by albumin

Tyrosinase activity decreases as the reaction proceeds and is inhibited by L-3,4-dihydroxyphenylalanine oxidation products. Indole and tryptophan inhibit tyrosinase reaction and bovine albumin protects against end-product(s) inhibition or inactivation. Since the same tyrosinase reaction products are indole compounds and some authors reported the binding of indole derivatives with albumin, it is here suggested that indole intermediates of melanin synthesis inhibit or inactivate tyrosinase.

6-Phosphogluconate Dehydrogenase, Glucose-6-Phosphate Dehydrogenase, Glucose-6-Phosphate Isomerase, and Hexokinase Activity Ratios in Some Human Tumor Cytosols

The ratios of some key enzymatic activities of carbohydrate metabolism have been measured in human tumor cytosols. The activities of whole hexokinase (low Km, EC 2.7.1.1 and high Km, EC 2.7.1.2), 6-phosphogluconate dehydrogenase (EC 1.1.1.43), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and glucose-6-phosphate isomerase (EC 5.3.1.9) change according to a biochemical pattern coherent with cell growth requirements. 6-phosphogluconate dehydrogenase activity was in each sample tested higher than glucose-6-phosphate dehydrogenase activity; this indicates that 6-phosphogluconate, a powerful inhibitor of glucose-6-phosphate isomerase, is unlikely to accumulate and inhibit this enzyme and glucose-6-phosphate channelling into glycolysis.

Double ventricular response to an extrastimulus in a patient with triple atrioventricular pathways

A patient with the Wolff-Parkinson-White Syndrome was studied through recordings of the intracardiac potentials and programmed atrial stimulation. During programmed atrial stimulation at progressively shorter coupling intervals (A1-A2 intervals), the His deflection was always recorded after the ventricular complex. Thus, at coupling intervals between 295 and 250 msec, there was a double ventricular response, one through the accessory pathway (QRS complex of the Wolff-Parkinson-White morphologic pattern) and the other by the normal atrioventricular pathway (normal QRS complex or with pattern of left bundle-branch block). At a coupling interval of 295 msec, the atrio-His (A-H) interval increased from 200 to 350 msec. This fact and the presence of two distinct A2-H2 intervals are suggestive of the existence of dual atrioventricular pathways, coexisting functionally with a lateral accessory bypass (Kent's bundle).

Nutritional inhibition of genetically determined renal disease and autoimmunity with prolongation of life in kdkd mice

Striking inhibition of development of renal disease and prolongation of lifespan have been achieved in kdkd mice by restricting their daily food intake. Restricting protein intake alone did not prolong life nor did it inhibit development of kidney disease. The kdkd nephronophthisis, although very different histologically from the renal disease of B/W mice, may also have immunological components. Like the immunologically based renal disease of B/W mice, renal disease in kdkd mice is decreased or eliminated histologically by dietary restriction, which inhibits development of autoimmunity directed toward the erythrocytes of these mice. Further analysis will be needed to elucidate the cause of progressive renal disease in both the kdkd and B/W models and to permit understanding of the profound influence of restriction of food intake on development and progression of these very different renal diseases.

Late hexokinase activity expression during Bufo bufo development

Hexokinase activity was detected in cytosols and homogenates from different developmental stages of Bufo bufo embryos starting from stage 17. Free glucose was measured in the embryo cytosol and was detected at each stage tested. At stage 15, a large increase of glucose content of the embryo cytosol occurs. Hexokinase expression in the embryo thus occurs after the increase of cytosol glucose content occurring at stage 15. The findings rule out that glucose by itself is the hexokinase inducer in vivo. The very low glucose utilization found by many authors during early amphibian development may be related to the late hexokinase expression during Bufo bufo development.

Dehiscence and active spore release in pathogenic strains of the yeast Metschnikowia bicuspidata var. australis: possible predatory implication

Strains of Metschnikowia bicuspidata var. australis, pathogenic to brine shrimp (Artemia salina), were observed to form asci which, upon reaching maturity, forcibly expelled their needle-shaped spores. The mechanical force responsible apparently originates from the formation of an ectoplasmic mucilage capable of exerting pressure over all of the ascus contents; when the apex of the peduncle ruptures, the ascospores are violently released. Cytochemical analyses indicated that the gel is a substance highly resistant to chemical and enzymatic hydrolysis. Its chemical nature is not known as yet. The morphogenetic events of this process are described, and its ecological implication, the possibility of active mechanical predation in yeast, is discussed.

A bacteriological study of the intestinal mucosa and luminal fluid of adults with acute diarrhoea

Bacteriological studies of jejunal mucosal biopsy specimens and contents were performed on 22 hospitalized adult patients with acute diarrhoea and 24 control normal subjects. None of the washed homogenates of the mucosal specimens were sterile and only one fluid specimen obtained from a control subject was sterile. A definite enteric pathogen was found in only five of the 22 diarrhoea patients. There was no qualitative difference in the bacterial profile of the jejunal mucosa and contents of the diarrhoea patients from that of the control subjects, but there were significant quantitative differences for some bacterial categories. In the control as well as diarrhoea subjects, there was no qualitative difference in the bacterial profile of the jejunal mucosa from that of the fluid, but there were significant quantitative differences for some bacterial categories. The significance of the findings is discussed.

The ecology of yeast flora associated with cactiphilic Drosophila and their host plants in the Sonoran desert

Yeasts were isolated from the rotting stems of 7 species of cereoid cacti and 4 species ofDrosophila which utilize them as host plants. The yeast most common among 132 nonidentical isolates from the cacti and 187 nonidentical isolates from the flies, respectively, were:Pichia membranaefaciens (59 and 126),Candida ingens (22 and 8),Torulopsis sonorensis (16 and 20), andCryptococcus cereanus (11 and 14). Isolates capable of utilizingD-xylose were recovered primarily fromD. pachea andL. schotti. Adult flies were present on the substrates whenP. membranaefaciens was at high concentrations. As the pH of the substrates increased, the percent ofC. ingens cells increased relative to other yeast species. Larvae were detected mainly in alkaline substrates, and since adults did not yieldC. ingens to the extent the substrates did,C. ingens may be important in larval nutrition.Torulopsis sonorensis was recovered mainly fromD. mojavensis and its host plants,M. gummosus andL. thurberi. The concentration ofT. sonorensis in the substrates was negatively correlated with the temperature of the substrate.Cryptococcus cereanus was found in high concentrations in suitable tissues for adult flies but most adults did not yield this species to any extent. The yeast habitat diversities from the substrates had the following order:L. thurberi > C. gigantea > C. gigantea soils ≫ M. gummosus > L. schotti > others. Habitat diversity is discussed in relation to the variation of the physical conditions and chemical composition of the substrates. The yeast habitat diversities from the flies had the orderD. pachea > D. mojavensis ≫ D. nigrospiracula > undescribed Species M. The degree of habitat diversity is possibly a function of the surface feeding behavior of the flies.

Specific activities of 6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase and glucose-6-phosphate isomerase during Bufo bufo development

It has been suggested by some authors that during amphibian development, due to the higher glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activity compared to that of 6-phosphogluconate dehydrogenase (EC 1.1.1.43), 6-phosphogluconate could accumulate in the embryo tissues and regulate the channelling of glucose-6-phosphate into glycolysis. Here, on the base of the specific activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate isomerase (EC 5.3.1.9) found in the embryos of Bufo bufo during development, it is discussed whether 6-phosphogluconate can accumulate and play a regulative role on glucose-6-phosphate metabolism in the anuran embryo.

Electron micrography study of the asci and ascospores of Metschnikowia Kamienski

Internal and surface structures of asci and ascospores were studied by transmission electron microscopy (TEM) and by scanning electron microscopy (SEM) to establish the character and number of ascospores within the ascus of Metschnikowia krissii. Enzyme digestion with snail gut enzymes and SEM examination suggested the presence of a single ascospore enclosed in a thick sheath of epiplasmic materials. Two closely associated ascospores without an epiplasmic sheath were clearly distinguishable from asci of M. bicuspidata var. chathamia when similarly treated. Ultramicrotomy and TEM established conclusively that M. krissii produced a single ascospore per ascus. Neither SEM nor TEM revealed any morphological detail of the ascospores of taxonomic significance.

Attempted validation of a "pragmatic classification of depression"

Limited aspects of Blinder's pragmatically derived classification of depressives based on syndrome characteristics were assessed. Blinder's syndrome descriptions were cast into items for an observer-rated interview and into a parallel, patient-rated schedule. Interobserver ratings were statistically reliable (γ′ = .78, p < .001). Patients' self-ratings were positively related to observer ratings (γ′ = .69, p = 01), but observers rated patients as more depressed than patients rated themselves ( t = 2.93, p = .01). Observer ratings only were factor analyzed. The unrotated factors obtained accorded better with previous factor analytic studies than with the syndrome aspect of Blinder's pragmatic classification.

Analytic-perceptual style and verbal conditioning

Relations among analytic-perceptual style, awareness, and desire for reinforcement within a Taffel-type verbal conditioning paradigm were assessed. Witkin's Embedded-figures Test and Mayman's Rorschach form level scores were analyzed separately as indices of analytic-style. Data were analyzed by multiple linear regression with linear contrasts. Embedded-figure scores did not relate to any others. But form level interactions with awareness and desire for reinforcement and a triple interaction provided limited support for the hypothesis that an active analytic style facilitates awareness and verbal conditioning, if the reinforcer is desired.