Microbiological dehydrogenation of polyfunctional Δ5-3β-acetoxy steroids by Corynebacterium mediolanum strain B-964

Summary A high-yield microbiological transformation of polyfunctional ⁵-3-acetoxy steroids, containing an additional ring E, by Corynebacterium mediolanum strain B-964 was carried out, resulting in the corresponding ⁴-3-ketones. It was shown that the type of transformation and the yield of the reaction depend on the degree of saturation of the ring E and on the position of the oxygen-containing substituents in it.     

Value of serum arabinitol for the management of Candida infections in clinical practice

To determine the value of serum arabinitol concentrations in clinical practice, we identified all patients at the University of Utah Medical Center for whom a serum arabinitol determination had been requested by the attending physician or housestaff to assist in the management of candidiasis. The patient populaton was divided into three categories on the basis of clinical and pathological findings: (1) superficial candidiasis, (2) possible deep, invasive candidiasis, and (3) definite, deep invasive candidiasis. Abnormal renal function was associated with elevated concentrations of serum arabinitol in proportion to the degree of renal dysfunction. Both the serum arabinitol concentration and the arabinitol/creatinine ratio were increased in the combined patient population with candidiasis relative to normal uninfected controls (p=0.06 and 0.001, respectively). However, neither of these tests reliably distinguished patients with invasive candidiasis from those with only superficial candidal disease.     

Immunomodulation by Histoplasma capsulatum products; polyclonal activation and mitogenic effects

The presence of reactive spleen cells to sheep red blood cells (SRBC) in nonimmunized BALB/c mice injected with histoplasmin, the culture filtrate of Histoplasma capsulatum, was monitored for 21 days following inoculation. Polyclonal activation, as evidenced by a sharp increase in the number of anti-SRBC rosetteforming cells (RFC), as well as an enhanced response to heterologous non-cross-reactive erythrocytes from other species, was found in the spleens of these rodents on Days 11 to 13. Elimination of B-cell-derived RFC by the addition of complement indicated that the erythrocyte-binding cells consisted of both T- and B-lymphocytes. An immunosuppressive effect was detected if histoplasmin was injected 2 days before the antigen (SRBC), but could be reversed by injecting the filtrate 30 min prior to the antigen, as is found with polyclonal activators displaying immunosuppressive activity. Histoplasmin also had a mitogenic effect on lymphocyte obtained from the spleen, bone marrow, and thymus similar in magnitude to that produced by lipopolysaccharide (LPS) and concanaval in A. The biological significance of these findings is discussed.     

Regulation of 3 beta-hydroxysteroid dehydrogenase activity by human chorionic gonadotropin, androgens, and anti-androgens in cultured testicular cells

delta 5-3 beta-Hydroxysteroid dehydrogenase is a key enzyme for testicular androgen biosynthesis and a marker for the Leydig cells. The hormonal regulation of this enzyme was studied in cultured rat testicular cells. Human chorionic gonadotropin (hCG) increased testosterone production in vitro while time course studies indicated a biphasic action of the gonadotropin on 3 beta-hydroxysteroid dehydrogenase activity. An initial stimulation (51%) of the enzyme was detected between 3 and 12 h of culture when medium testosterone was low. This is followed by an inhibition of 3 beta-hydroxysteroid dehydrogenase activity on days 2 and 3 of culture when medium testosterone was elevated. Concomitant treatment with a synthetic androgen (R1881) inhibited 3 beta-hydroxysteroid dehydrogenase activity and testosterone production in hCG-treated cultures while an anti-androgen (cyproterone acetate) increased 3 beta-hydroxysteroid dehydrogenase activity and testosterone biosynthesis. Addition of 10(-5) M spironolactone, an inhibitor of 17 alpha-hydroxylase, blocked the hCG stimulation of testosterone production but increased medium progesterone. In the absence of the secreted androgen, hCG stimulated 3 beta-hydroxysteroid dehydrogenase activity in a time- and dose-related manner. Furthermore, hCG stimulation of 3 beta-hydroxysteroid dehydrogenase activity and progesterone accumulation in spironolactone-supplemented cultures was decreased by concomitant treatment with R1881 but was not affected by cyproterone acetate. The inhibitory effect of R1881 was blocked by the anti-androgen. In the absence of hCG, treatment with testosterone, dihydrotestosterone, or R1881, but not promegestone, alone also inhibited 3 beta-hydroxysteroid dehydrogenase activity while the inhibitory effect of testosterone was blocked by cyproterone acetate. Thus, hCG stimulates 3 beta-hydroxysteroid dehydrogenase activity in cultured testicular cells. The androgenic steroidogenic end products, in turn, inhibit this enzyme. The hormonal regulation of 3 beta-hydroxysteroid dehydrogenase activity may be important in the ultrashort loop autoregulation of androgen biosynthesis.     

Immunosuppressive effect of Entamoeba histolytica extract on hamsters

The immune response to sheep red blood cells (SRBC) in mice and hamsters injected with an extract of entamoeba histolytica was studied. Both the primary and secondary immune response, measured by anti-SRBC antibody titers, were unaltered in the mouse, while a significant depression of the primary, but not the secondary, response was observed in the hamster. The effect was greatest when the amebic extract (AE) and SRBC were injected on the same day. The number of anti-SRBC rosettes formed in the spleen cells of hamsters treated with both AE and SRBC on day 0 was measured from days 1-16. The response peaked on day 13, while cells from animals injected with SRBC alone gave a maximal response on day 5. The formation of anti-SRBC rosettes in T-lymphocyte-enriched spleen cells treated with anti-gamma globulin serum and complement was almost abolished for the duration of the experiment. It is suggested that the mechanism responsible for this immunosuppressive phenomenon could involve early interference in the afferent limb of the immune response.     

Stimulation of Free Fatty Acid and Diacylglycerol Accumulation in Cerebrum and Cerebellum During Bicuculline-Induced Status Epilepticus. Effect of Pretreatment with α-Methyl-p-Tyrosine and p-Chlorophenylalanine

The pool size and composition of free fatty acids (FFA) and diglycerides (DG) from the cerebrum and cerebellum of rats undergoing bicuculline-induced seizures were studied. A fourfold increase in cerebral FFA occurred 3-4 min after bicuculline injection; arachidonic and stearic acids were the principal fatty acids accumulated. Cerebellar FFA also increased, but to a lesser extent. An increased production of arachidonic acid took place in the cerebrum as a function of time after bicuculline injection. Other fatty acids produced were oleic, palmitic, and docosahexaenoic acids. A twofold increase in cerebral arachidonic acid was seen at the time of the first generalized tonic-clonic convulsion. However, a 13- to 17-fold increase in arachidonic acid was seen approximately 5-6 min after bicuculline injection. The rise in other FFA was much smaller. Stearoyl- and arachidonoyl-DG were also accumulated. The drug alpha-methyl-p-tyrosine was found to (a) potentiate the bicuculline-stimulated release of cerebellar FFA, and (b) inhibit by 70% the production of stearoyl- and arachidonoyl-DG in the cerebrum and cerebellum. Basal production of FFA was stimulated by p-chlorophenylalanine, but the drug had no effect on the bicuculline-induced changes. Hydrolysis of phospholipids enriched in stearoyl-arachidonoyl groups, such as phosphatidylinositol of excitable membranes, may be stimulated during seizures.     

Evidence for two waves of induction of DNA enzymes in stimulated human lymphocytes

The stimulation of human lymphocytes with phytohaemoagglutinin induces the appearance or increase of several enzymes of DNA metabolism [Pedrini etal., Biochem. Biophys. Res. Comm., 47:1221(1972)]. With long times of stimulation, two phenomena are observed; an increase in the levels of DNA polymerase, of a DNase acting on single-stranded DNA, and of an endonuclease, occurring between the third and fourth day, in parallel with a wave of DNA synthesis;a second wave of increase of the same enzymes and of DNA ligase,occurring between the fifth and eight day when the DNA replication rate, as measured by thymidine-pulses, has decreased to values close to the background.     

Stand microclimate and physiological activity of tree leaves in an oak-hornbeam forest

Summary In an uneven-aged, multi-species oak-hornbeam forest at Báb, SW Slovakia (former IBP Forest Research Site), a series of micrometeorological and ecophysiological measurements started in 1985. The aims of the work are to improve understanding of physiological processes (photosynthesis, respiration, and transpiration) of adult trees and stand microclimate, to collect data for simulation of the canopy (stand) photosynthesis and for ecological synthesis of the functioning of the forest ecosystem. In this paper, photosynthetically active radiation (PAR), air temperature (AT) and relative humidity (RH), wind speed (WS), and CO₂ concentration ([CO₂]) in and above the forest are characterized for the fully leaved season, using diurnal courses, vertical profiles and isodiagrams (isopleths). Approximately 50% of incident PAR was absorbed by the upper 4–5 m layer of leaves and only approximately 5% or less penetrated to the forest floor. Vertical gradients of AT and RH were generally low, but large differences in diurnal ranges of AT and RH were observed between vertical levels. The upper leaf canopy greatly reduced WS, and at a height of about 14 m above the ground it was close to zero. The highest diurnal [CO₂] maximum and variations occurred at 1 m above the ground, and the lowest above the forest. In good light conditions in the forest, the entire leaf canopy (overstorey and understorey canopy) is a large sink of CO₂. At night the forest stand is a source of CO₂, the largest internal source being the soil and forest floor.