Effects of phenytoin on cell-mediated immunity

Summary The effects of phenytoin on cellular immunity were examined in murine models. Fresh splenocytes were obtained from mice which had received 1 mg/day of phenytoin i.p. for 28 days. The serum concentration of phenytoin in these animals was 10–10 g/ml. The proliferative response of splenocytes to mitogens was assessed by ³H-thymidine incorporation. The cytotoxic activities of cells such as natural killer (NK) cells, cytotoxic T lymphocytes (CTL), and lymphokine-activated killer (LAK) cells were estimated by a 4-h ⁵¹Cr release assay. The ³H-thymidine incorporation of splenocytes was reduced significantly (P<0.01) in phenytoin-treated mice. The NK and CTL activities of splenocytes from phenytoin-treated mice were significantly suppressed. However, the LAK activity of phenytoin-treated mice was equal to that of control mice.     

Photonastic and thermonastic opening of capitulum in dandelion,Taraxacum officinale andTaraxacum japonicum

The capitula ofTaraxacum officinale andT. japonicum open in response to temperature rise at lower temperatures (thermonasty), and in response to light at higher temperatures (photonasty), as was the case inT. albidum. The capitula ofT. officinale could respond to the same temperature rise more sensitively than those ofT. albidum orT. japonicum. The minimum temperature for photonastic opening is as low as 13 C forT. officinale, while that forT. albidum andT. japonicum is about 18 C. That is why the capitula ofT. officinale opened earlier than those ofT. albidum andT. japonicum in the morning in April under natural conditions. The capitulum continued to be open for about 13–14 hr inT. officinale and about 8–11 hr inT. japonicum and inT. albidum both under natural conditions in April and even under constant light-temperature conditions, suggesting that the time of capitula-closing in these three species is not controlled by changes in environmental factors (light and/or temperature).     

In vitro increase of histidine decarboxylase activity and release of histamine by peritoneal resident cells of mast cell-deficient W/Wv mice; possible involvement of macrophages

When peritoneal resident cells (PRCs) of genetically mast cell-deficient WBB6F1-W/Wv mice were cultured in vitro for 5 h at 37 degrees C, their histidine decarboxylase [HDC, L-histidine carboxylase, E.C. 4.1.1.22] activity increased 10-fold. Since inhibitors for energy production and mRNA and protein syntheses inhibited this increase of HDC activity, it appeared to represent de novo synthesis of the enzyme, i.e., induction. This increase was followed by an increase in the amount of histamine in the culture medium of the cells, indicating that histamine synthesized by the induced HDC was not stored in the cells but was quickly released. Mast cells were not involved in the HDC induction, because the extents of HDC induction in PRCs of W/Wv and wild type +/+ mice were similar. The removal of T cells with anti-Thy-1,2 antibody and complement from the PRCs did not affect the HDC induction, but the removal of phagocytes decreased the induction to one-tenth in spite of a 2-fold increase in the proportion of B cells in the PRCs. After separation of the PRCs into adherent and non-adherent fractions, the increase in HDC activity was found to be associated with the adherent fraction that was mostly positive to esterase staining. These results suggest that HDC was induced in peritoneal macrophages.     

Residual B cell function in patients with long-standing NIDDM and its relation to metabolic control and diabetic complications

We have evaluated the residual pancreatic B cell function by glucagon load test in 28 patients with non-insulin-dependent diabetes mellitus (NIDDM) of a duration of 20 years or more. The increase in serum C-peptide at 6 minutes after glucagon administration (delta C-peptide) was used as an index of residual B cell function. There was much less delta C-peptide in patients treated with insulin than in those treated with sulfonylurea (p less than 0.05), and it was significantly correlated with the body mass index (r = 0.40, p less than 0.05). Long term metabolic control assessed by the average annual mean fasting blood glucose for the observation period (mean, 21 years) was not correlated with delta C-peptide (r = -0.13). The prevalence of retinopathy which needed photocoagulation therapy and of neuropathy in patients with poor residual B cell function (delta C-peptide less than or equal to 0.3 ng/ml) was the same as that in those with good residual B cell function (delta C-peptide greater than or equal to 1.0 ng/ml). The present study shows that the residual B cell function is not correlated with long term glycemic control and the prevalence of diabetic complications in long-standing NIDDM patients.     

Multiple enzymes related to differentiation of lymphocyte subpopulations in man

We studied the relation of various enzymes to subpopulations of lymphocytes in man. T cell-rich fractions were separated with a nylon column from mononuclear cells in the buffy coat. Comparing the enzymatic profiles of the two fractions, we found that the difference between the two groups came from the dominancy of B cells and/or macrophages in the former fraction, and from that of T cells in the latter. The enzymes characterizing T cells included N-Ac-beta-D-glucosaminidase (GlcNAc-ase), prolyl endopeptidase (Post-Pro-Enz), and dipeptidyl aminopeptidase IV (DAP-IV), whereas those characterizing B cells and/or macrophages include poly(ADP-ribose) synthetase, leucine aminopeptidase (Leu-AP), AP-B, cathepsin B, sialidase, and AP-A. Inhibitors of these enzymes may lead to modification of the function of T and B cells.     

Changes in relationship between blood glucose level and plasma 1,5-anhydroglucitol level in KK mice

We compared the relationship of the blood glucose level to the plasma 1,5-anhydroglucitol (1,5AG) level between KK mice with abnormal glucose metabolism and ICR mice as controls. Although the plasma 1,5AG level did not show any significant correlation with the blood glucose level in the controls, it tended to logarithmically decrease with the rise in the blood glucose level in KK mice. Thus it is possible that the plasma 1,5AG level is specifically related to the abnormal glucose metabolism in this model of diabetes mellitus and that its routine examination in diabetic patients may help delineate the metabolic derangement in the disease.     

Mechanism of biosynthesis of unsaturated fatty acids in Pseudomonas sp. strain E-3, a psychrotrophic bacterium.

Biosynthesis of palmitic, palmitoleic, and cis-vaccenic acids in Pseudomonas sp. strain E-3 was investigated with in vitro and in vivo systems. [1-14C]palmitic acid was aerobically converted to palmitoleate and cis-vaccenate, and the radioactivities on their carboxyl carbons were 100 and 43%, respectively, of the total radioactivity in the fatty acids. Palmitoyl coenzyme A desaturase activity was found in the membrane fraction. [1-14C]stearic acid was converted to octadecenoate and C16 fatty acids. The octadecenoate contained oleate and cis-vaccenate, but only oleate was produced in the presence of cerulenin. [1-14C]lauric acid was aerobically converted to palmitate, palmitoleate, and cis-vaccenate. Under anaerobic conditions, palmitate (62%), palmitoleate (4%), and cis-vaccenate (34%) were produced from [1-14C]acetic acid, while they amounted to 48, 39, and 14%, respectively, under aerobic conditions. In these incorporation experiments, 3 to 19% of the added radioactivity was detected in released 14CO2, indicating that part of the added fatty acids were oxidatively decomposed. Partially purified fatty acid synthetase produced saturated and unsaturated fatty acids with chain lengths of C10 to C18. These results indicated that both aerobic and anaerobic mechanisms for the synthesis of unsaturated fatty acid are operating in this bacterium.     

Hydrolytic enzyme activities in germinating spores ofAdiantum capillus-veneris L.

Changes in hydrolytic enzyme activities were investigated during spore germination ofAdiantum capillus-veneris L. The spores were incubated for 3 days in the dark at 25 C for imbibition, and then germination of the spores was induced by continuous irradiation with red light. At day 2 after onset of the red light irradiation, rhizoids appeared out of spore coats and protonemal cells became visible on the following day. Lipase occurred in dry spores and its activity decreased during 3 days of dark incubation. The activity started to increase when the spore germination was induced by red light irradiation. On the other hand, amylolytic and aminopeptidase activities which were also detected in dry spores decreased continuously during the dark incubation and following the germination process. RNase activity also decreased during 3 days of dark incubation but the activity was retained thereafter at a constant level with or without red light irradiation. Developmental patterns of these hydrolytic enzymes were classified into two groups: One decreased during imbibition and dark incubation but increased after red light irradiation and the other continuously decreased during dark incubation and germination. These results are discussed in relation to compositional changes of cell constitutions such as lipid, sugars, proteins and amino acids during spore germination.     

Induction of rapid testicular growth in Japanese quail by phasic electrical stimulation of the hypothalamic photosensitive area

Summary Optic fibers were implanted stereotaxically into the brain of immature male Japanese quail reared under short-day photoperiod (lights on from 1000 to 1800 h), and photosensitive sites in the hypothalamus were examined using gonadal growth and associated hormonal changes as the indices.In the subsequent experiments, bipolar (coaxial) electrodes were implanted chronically using predetermined coordinates for highly photosensitive sites. Henceforth the birds received brief electrical stimulation (square wave, 100 Hz, 100A, 2 min) once daily for 21 consecutive days. When the electrical stimulation was applied early in the dark period, marked gonadal growth was induced, but identical stimulation given in the light period resulted in no testicular growth. The response curve of testicular weight vs clock time of electrical stimulation has a prominent peak at 3 h after the onset of dark. Apparently, the neural complex in the photosensitive area of the quail hypothalamus responds to electrical stimulation as it does to light. We conclude that in photoperiodic birds the principal factor which determines the magnitude of gonadal responses is not the intensity of the stimulus but its timing (circadian phase).Abbreviations GnRH gonadotropin releasing hormone - LD light and dark - LED light emitting diode - CRT cathode ray tube - LH luteinizing hormone - OD outer diameter - ID inner diameter     

Cadmium-induced stimulation of lipogenesis from glucose in rat adipocytes

Exposure of adipocytes of rats to CdCl2 caused acceleration of [3-3H]glucose incorporation into lipid maximally at 500 microM in Krebs-Ringer bicarbonate buffer, pH 7.4, containing 0.2% albumin. T.l.c. of the lipids extracted from adipocytes showed that Cd2+ increased labelling of di- and tri-[14C]acylglycerols predominantly. With increasing concentrations of glucose the apparent Km value was not affected by Cd2+, but the V value was increased, similarly to the effect of insulin. In the presence of insulin, Cd2+ (5 microM) exerted a consistent additive effect with a stimulatory effect of insulin on lipogenesis at all concentrations of insulin tested (5-50 mu units/ml). The stimulation was observed at a high concentration of glucose, suggesting that Cd2+ accelerated intracellular metabolism of glucose, mimicking insulin. However, although Zn2+ and Mn2+ stimulated the transport at a rate similar to that observed with insulin (200 mu units/ml), Cd2+ had no stimulating effect on the membrane transport of 3-O-methylglucose. The biological potency of Cd2+ and the insulin-like effects of Zn2+, both of which metals belong to the same group in the Periodic Table, are similar towards glucose metabolism, but quite different towards glucose transport.