Aspirin enhances evaporation in hydrated and dehydrated rats

The effect of acetysalicylic acid (aspirin) on thermoregulation in a warm environment was studied in hydrated and dehydrated adult rats to test the hypothesis that dehydration hyperthermia can be modified by an antipyretic drug. Metabolic rate (MR), evaporative water loss (EWL), and deep body temperature (Tb) were measured during 2 h of exposure to an ambient temperature of 36 degrees C after the rats had received an oral pellet of aspirin (100 mg.kg-1) or placebo. The dehydrated placebo group had a higher Tb and lower EWL than the hydrated placebo group. Aspirin increased MR and EWL in both hydrated and dehydrated animals. Aspirin did not affect Tb in hydrated rats, but reduced Tb by 0.2 degree C in dehydrated rats during the heat exposure. The elevation in EWL appears to be a thermoregulatory response to increased heat production in both hydrated and dehydrated animals after aspirin treatment. The possibility that aspirin may act in dehydrated animals to restore central thermosensitivity toward hydrated levels needs to be tested further.     

The effect of salts in fermenting mashes on the microbiological assay ofl-lysine

During a study of the effects of high concentrations of NaCl, NaNO₃ and KC1 on the production of lysine bySaccharomyces cerevisiae during the fermentation of glucose (Richmond 1980) it was learned that amounts of salt greater than 0.6 M in the microbiological assay sample could change the apparent concentration of lysine in the sample. This could be corrected by adding to the lysine assay broth sufficient salt to match the concentration in the sample tube and then developing a revised standard curve. The additional salt, in turn, required that the microbiological assay time be lengthened.     

Brain peptides and glial growth. I. Glia-promoting factors as regulators of gliogenesis in the developing and injured central nervous system

Glia-promoting factors (GPFs) are peptides of the central nervous system which accelerate the growth of specific glial populations in vitro. Although these factors were first discovered in the goldfish visual system (Giulian, D., Y. Tomozawa, H. Hindman, and R. Allen, 1985, Proc. Natl. Acad. Sci. USA., 83:4287-4290), we now report similar peptides are found in mammalian brain. The cerebral cortex of rat contains oligodendroglia-stimulating peptides, GPF1 (15 kD) and GPF3 (6 kD), as well as astroglia-stimulating peptides, GPF2 (9 kD) and GPF4 (3 kD). The concentrations of specific GPFs increase in brain during periods of gliogenesis. For example, GPF1 and GPF3 are found in postnatal rat brain during a peak of oligondendroglial growth while GPF2 and GPF4 are first detected at a time of astroglial proliferation in the embryo. Stab wound injury to the cerebral cortices of rats stimulates astroglial proliferation and induces marked elevations in levels of GPF2 and GPF4. Our findings suggest that two distinct classes of GPFs, those acting upon oligodendroglia and those acting upon astroglia, help to regulate cell growth in the developing and injured central nervous system.     

Characteristics of the β-Adrenoreceptor from Neuronal and Glial Cells in Primary Cultures of Rat Brain

The cellular characteristics of the beta-adrenoreceptor in glial and neuronal cells from the newborn rat brain were determined by (-)-[125I]iodocyanopindolol binding. In membranes from both cell types, the binding was saturable and from competition assays the potency series of (-)-isoproterenol greater than (-)-epinephrine = (-)-norepinephrine greater than (+)-isoproterenol was observed. 5'-Guanylyl-imidodiphosphate reduced the affinity of (-)-isoproterenol for the beta-adrenoreceptor from glial cells but had no effect on agonist affinity in neuronal cells. Chronic treatment of both cell types with (-)-isoproterenol reduced the receptor content and the capacity of the agonist to increase the cellular cyclic AMP content. However, the receptor recovery after chronic agonist treatment was faster in glial cells (72 h) than neuronal cells (120 h) and was blocked by cycloheximide. Treatment of both types with the irreversible beta-blocker bromoacetylalprenololmentane (2 microM) reduced the receptor content by 78% but no receptor recovery was observed for 120 h after the initial receptor loss. The data indicated that the majority of beta-adrenoreceptors in both cell types are the beta-1 subtype, but show some differences in receptor-agonist interactions. Furthermore, these CNS cells may be useful models for regulatory studies on the beta-adrenoreceptor.     

Dilute acid hydrolysis of paper birch: kinetics studies of xylan and acetyl-group hydrolysis

Batch hydrolysis kinetics of paper birch (Betula papyrifera) xylan and its associated acetyl groups in dilute sulfuric acid have been measured for acid concentrations of between 0.04 and 0.18M and temperatures of between 100 and 170 degrees C. Only 5% of the cellulose was hydrolyzed for up to 85% xylan removal. Rate data were correlated well by a parallel reaction model based on the existence of reactive and resistant xylan portions. The resulting rate equation predicts the experimental xylan concentrations in the residue to within 10%. Hydrolysis of xylan-associated acetyl groups was found to occur at the same rate as that of xylan, except at 100 degrees C, where acetyl is released preferentially. No effect of acid concentration on the rate of acetyl removal relative to that of xylan was evident.     

Spontaneous epimerization of (S)-deoxycoformycin and interaction of (R)-deoxycoformycin, (S)-deoxycoformycin, and 8-ketodeoxycoformycin with adenosine deaminase

(R)-Deoxycoformycin (pentostatin), (S)-deoxycoformycin, and 8-ketodeoxycoformycin were compared as inhibitors of calf intestine adenosine deaminase. In contrast to (R)-deoxycoformycin, which had been demonstrated as a tight-binding inhibitor with a dissociation constant of 2.5 X 10(-12) M [Agarwal, R. P., Spector, T., & Parks, R. E., Jr. (1977) Biochem. Pharmacol. 26, 359-367], (S)-deoxycoformycin and 8-ketodeoxycoformycin are slope-linear competitive inhibitors with respect to adenosine. The kinetic constants are 33 microM for inhibition by (S)-deoxycoformycin, 43 microM for 8-ketodeoxycoformycin, and 16 microM for the Km for adenosine. The stereochemistry of carbon 8 of the diazepine ring therefore causes a (1.3 X 10(7]-fold change in the affinity for the enzyme which is specific for the R configuration. This difference is attributed to an induced conformational change which cannot be initiated by the S isomer or the 8-keto analogue of (R)-deoxycoformycin. The studies were complicated by the need to remove traces of tight-binding inhibitor(s) from (S)-deoxycoformycin, since as little as 0.001% of the R isomer causes significant inhibition. The R and S isomers of deoxycoformycin are unstable in neutral or mildly acidic aqueous solutions. Isomerization of the secondary hydroxyl at carbon 8 of the diazepine ring is one of the reactions, resulting in S to R and R to S conversions for deoxycoformycins. Opening of the aglycon is also a major reaction. The tight-binding inhibitor generated from (S)-deoxycoformycin was identified as (R)-deoxycoformycin by high-pressure liquid chromatography, spectroscopy, circular dichroism, and chemical criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxidation of oxalate and polyamines by rat peroxisomes

During renal failure, polyamines and oxalate levels are elevated in the serum and the glomerular filtrate and are dumped by the kidney. Both of these compounds can be catabolized by oxidative reactions. We have, therefore, investigated the intracellular distribution of oxalate oxidase and of a polyamine oxidase in normal female rat kidney and liver. Polyamine oxidase was demonstrable, using spermidine as substrate in the cerous peroxyhydrate procedure of Briggs et al., in peroxisomes of kidney tubule cells and of hepatocytes. Oxalate oxidase could not be studied with this technique due to precipitation of cerium oxalate in the incubation medium. To demonstrate oxalate oxidase, and to confirm the polyamine oxidase localization, we incubated aldehyde-fixed tissue in a diaminobenzidine medium at pH 8, following the approach of Veenhuis et al., in which oxidases are demonstrated by virtue of their production of H2O2, which then serves as a substrate for endogenous catalase. Using oxalate or spermidine as substrate with this approach, we found reaction product in typical renal peroxisomes; we also found reaction product, with the polyamine substrate, in hepatocyte peroxisomes. To strengthen the conclusion that the oxidases themselves are present in peroxisomes, we used a light microscopic method, based on the tetrazolium procedures of Allen and Beard to demonstrate polyamine and oxalate oxidase activities in bodies with the distribution of renal peroxisomes.     

Immunocytochemical demonstration of neuropeptides and serotonin in the tapeworm Diphyllobothrium dendriticum

Summary The present immunocytochemical study concerns the distribution of four neuropeptides, FMRF-amide, vasotocin, leu-enkephalin and neurotensin, and of the bioamine serotonin in the plerocercoid larva of Diphyllobothrium dendriticum. Anti-FMRF-amide and vasotocin-reactivity occurs in perikarya and nerve fibres in the CNS and PNS of this worm. The peptide-containing fibres surround and seem to innervate the musculature and to terminate beneath the basal lamina of the tegument at the inner surface of the bothridia, suggesting a neurotransmitter function. Antileu-enkephalin reaction occurs in perikarya and fibres in the main nerve cords and in the PNS. Anti-neurotensin reactive fibres were observed in the neuropile of the nerve cords. Serotonin immunoreactivity was found in neurons in the ganglionic commissure of the brain and along the main nerve cords. This study is the first immunocytochemical identification of neuropeptides and serotonin in a parasitic flatworm and the information gained may be of importance for the development of new antihelminthics.     

Cyclic adenosine 3'5' monophosphate stimulates prostaglandin E production by human adherent synovial cells

Production of prostaglandin E (PGE) by rheumatoid synovium appears important to regulation of the pathologic process in rheumatoid arthritis. Cells derived from human synovium by proteolytic digestion produce large amounts of PGE which in turn can elevate synovial cell cAMP levels and inhibit cell proliferation. Data presented here indicate that cAMP can further increase production of PGE from adherent synovial cells (ASC). PGE production occurs over 12-72 hr and is not due to the ability of cAMP to inhibit cell proliferation. Exposure of cells to cAMP results in increased release of 3H arachidonic acid from precursors but not in activation of the cyclooxygenase enzyme. This phenomenon suggests the presence in adherent synovial cells of a mechanism for amplifying PGE production.     

Isolation and sequence analysis of a cDNA encoding the ATP/ADP translocator of Zea mays L.

A cDNA complementary to the mRNA for the ATP/ADP translocator of maize (Zea mays L.) has been identified by virtue of hybridisation with the homologous gene from yeast. The cloned cDNA has been shown by DNA sequence analysis to contain an open reading frame of 954bp., which encodes a polypeptide of molecular weight 40,519. This polypeptide exhibits a high degree of homology to the translocator polypeptides of beef heart and Neurospora crassa mitochondria.