Search PubMed⌕ Search

Biomedical subjects

R C Wiggins

Publications and source records attributed to R C Wiggins.

At least 109 records · Page 6Linked to original sources
PubMed1984

In vitro activation of the contact (Hageman factor) system of plasma by heparin and chondroitin sulfate E.

A large number of negatively charged macromolecules, including DNA, glycosaminoglycans, and proteoglycans, were tested as possible activators of the contact (Hageman factor) system in vitro. Activation was assessed by conversion of prekallikrein to kallikrein, as determined by amidolytic assay and by cleavage of 125I-Hageman factor into 52,000- and 28,000-dalton fragments. Of particular interest to these studies, heparin proteoglycan and glycosaminoglycan from rat peritoneal mast cells, and squid chondroitin sulfate E, which is representative of the glycosaminoglycan from cultured mouse bone marrow derived mast cells, induced the reciprocal activation between Hageman factor and prekallikrein. In addition, naturally occurring heparin glycosaminoglycans from pig mucosa, bovine lung, and rat mast cells also induced activation. In contrast, native connective tissue matrix glycosaminoglycans and proteoglycans from several sources were inactive, although when one such chondroitin sulfate was further sulfated in vitro, it gained activity. When the negative charge of the activating agents was blocked by the addition of hexadimethrine bromide, the cleavage of 125I-Hageman factor in the presence of prekallikrein was prevented. The active negatively charged macromolecules induced cleavage of 125I-high molecular weight kininogen in normal plasma but not in Hageman factor-deficient or prekallikrein-deficient plasmas. Reconstitution of prekallikrein-deficient plasma with purified prekallikrein restored the kininogen cleavage upon addition of the active proteoglycans. These results suggest that both heparin from connective tissue mast cells and highly sulfated chondroitin sulfate E from cultured mouse bone marrow derived mast cells (which are considered synonomous with mucosal mast cells) could activate the contact system of plasma subsequent to an activation secretion response.

Animals↗
PubMed1983

Kinin release from high molecular weight kininogen by the action of Hageman factor in the absence of kallikrein.

Proteolysis of 125I-high molecular weight (Mr) kininogen occurred in kaolin-activated plasma which was deficient in prekallikrein, but not in plasma which lacked both prekallikrein and Hageman factor (HF) activity. The implication of this observation is that HF itself might be capable of releasing kinin from high Mr kininogen. This concept was further supported by the following studies. In a purified protein system rabbit (Mr = 80,000) two-chain activated HF (alpha-HFa) incubated with human 125I-high Mr kininogen caused rapid proteolysis of the kininogen in the presence, but not in the absence, of kaolin. This was in contrast to the effect of kallikrein on proteolysis of high Mr kininogen which was inhibited 10-fold by the presence of kaolin. The possibilities that the alpha-HFa preparation was contaminated by rabbit kallikrein or that the human high Mr kininogen preparation was contaminated by human prekallikrein were excluded by using specific antibodies (IgG) against these proteins. The proteolytic fragments of 125I-high Mr kininogen generated by both alpha-HFa and kallikrein were indistinguishable by sodium dodecyl sulfate-polyacrylamide gel analysis. Bioassayable kinin was released from high Mr kininogen following incubation with alpha-HFa in the presence of kaolin. The amount of kinin released in proportion to the extent of proteolysis was the same for both kallikrein and alpha-HFa. The data show that activated Hageman factor may cause release of kinin by proteolytic cleavage of high Mr kininogen. This phenomenon occurs not only in a purified system of proteins but also in kaolin-activated plasma.

Animals↗
PubMed1983

Distribution of radioactivity among total myelin protein amino acids following administration of labeled glycine, leucine, or methionine.

This paper analyzes the distribution of radioactivity in the different amino acids of brain myelin protein for up to 6-7 weeks after an intracranial pulse administration of radioactive leucine, glycine, or methionine. Results show that there is no significant accumulation or reutilization of protein radioactivity in any form other than the one administered.

Amino Acids↗
PubMed1983

Postnatal increase in the metabolism of leucine and valine.

The catabolism of tritium-labeled leucine, valine, and glycine was determined by measuring the appearance of tritium-labeled water at various postnatal and adult ages in rats. Results for leucine and valine show a marked increase in the formation of labeled water during the 3rd postnatal week. The partial exclusion of leucine and valine from brain, as a result of the blood-brain barrier, particularly enhances observation of labeled water formation in that the product (water) and precursor (amino acid) are largely separated (supporting experiments demonstrate the prior existence of the blood-brain barrier for leucine). Results for glycine indicate its extensive metabolic degradation at all postnatal ages. These data indicate that the metabolic rate of intraperitoneally administered, radioactively labeled leucine and valine changes appreciably during early postnatal development. The early postnatal manifestation of human disorders of branched-chain amino acid metabolism is consistent with the chronology of development in the rat.

Age Factors↗
PubMed1982

The synthesis of myelin and brain subcellular membrane proteins in the offspring of rats fed ethanol during pregnancy.

Pregnant Long-Evans rats received either: (1) liquid diet containing 5.15% ethanol; (2) liquid diet pair fed to (1) for total calories; or (3) liquid diet ad libitum. These special diets were administered from the 5th through the 18th days of gestation. Dams received standard laboratory chow and water ad libitum before and after the test interval. Additional dams received standard chow and water throughout the study. Birth weights of offspring in the ethanol group were lower than for offspring of the pair-fed or control groups, and their subsequent growth lagged behind the other groups. Neonate deaths in the ethanol group outnumbered other deaths. Eye opening was delayed, and brain weights appeared low from 16 to 30 days postnatal age, The onset of myelin synthesis was delayed by several days; however, by 30 days of age, the rate of myelin synthesis and net accumulation was comparable to the offspring of pair-fed controls. Thus, the effect of ethanol on brain myelination in the offspring of subject females appears as a delay in myelin initiation and cannot be fully explained by caloric undernourishment. An unexpected observation involved offspring of females fed standard chow throughout the study. The brain myelin concentration in this group was lower than for any of the other groups, which may relate to the higher fat content of the liquids diets and/or the comparatively slow weight gain of pregnant rats on standard chow.

Animals↗
PubMed1982

Catecholamines in rat brain following postnatal undernutrition and nutritional rehabilitation.

Norepinephrine and dopamine were examined in 19 discrete brain areas from the telencephalon, diencephalon, and mesencephalon of nutritionally rehabilitated adult rats following postnatal undernutrition from birth through 21 days of age. Following rehabilitation, catecholamine levels were not significantly different from control values in any of the areas examined. Catecholamine concentrations in young, undernourished rats are generally elevated (either from stress or from nutritional insufficiency). Data presented here show that whichever case is true, the early effect of undernourishment is transient and that normal values are restored by nutritional rehabilitation.

Amygdala↗
PubMed1982

Synthesis of myelin, particulate, and soluble protein subfractions of rat sciatic nerve during the early stage of Wallerian degeneration: a comparison of metabolic studies using double and single isotope methods and recovery.

The recovery, electrophoretic composition and synthesis of the myelin, particulate protein and soluble protein subfractions of rat sciatic nerve were compared in normal, sham-operated, and degenerating rat sciatic nerve at one, three and five days after neurotomy. Both single and double isotope methods were used to measure changes in synthesis in vitro and double isotope methods were used in vivo. The wet weights of nerves undergoing Wallerian degeneration for 5 days increased by 40 percent compared to normal and sham-operated nerves. The recovery, specific radioactivity, and synthesis of the myelin was reduced. The effect on myelin protein synthesis was similar in vitro and in vivo. The myelin loss was relatively constant in amount (30-40 microgram) regardless of differences in nerve sizes of young and old rats, consequently the percentage of myelin loss was inversely proportional to nerve size. The recovery of particulate protein increased, its rate of synthesis remained unchanged, and accordingly the specific radioactivity was decreased. The recovery, specific radioactivity, and the rate of synthesis of the soluble protein fraction were all elevated. The protein composition of the three fractions, as analyzed qualitatively by polyacrylamide disc gel electrophoresis, remained essentially unchanged through five days of degeneration. With regard to comparisons of the single and double isotope methods, results shows that the latter are more ideally suited to measuring changes in synthesis during the non-steady state conditions that are characteristics of rapid degeneration.

Animals↗
PubMed1982

Relative halothane accumulation in brain subcellular membranes in vitro.

The accumulation of halothane in brain homogenates was compared with halothane accumulation in brain during inhalation at anesthetic and subanesthetic levels. Anesthesia is achieved at a tissue concentration well below the halothane solubility in brain tissue. Analysis of halothane in the particulate solids of brain homogenate and in purified subcellular membranes indicates that a membrane constituent (presumably the lipids) acts as an ideal solvent in which halothane is fully miscible. Therefore, membranes offer a local microenvironment in which halothane accumulation deviates from Henry's law. Specifically, we observe that even slight increases of halothane in a saline medium result in a relatively large increase in the concentration of halothane in subcellular membranes suspended in the medium, eventually leading to solvation of the membrane in halothane. This observation offers a ready explanation for the high degree of positive correlation between MAC and lipid solubility and the small difference between anesthetic and lethal concentrations of halothane during inhalation. The rate of halothane increase in myelin exceeded the rate in other brain subcellular membranes, indicating that a major site of halothane localization is within this subcellular membrane.

Animals↗
PubMed1982

Myelin development and nutritional insufficiency.

Postnatal undernourishment does not greatly retard the generation of rat brain cells, although there is a slight reduction in total cell numbers and brain size. Possibly the maturation of cells is more severely affected. The ratio of myelinated to non-myelinated fibers is greatly reduced in the corpus callosum and pyramidal tract, and presumably in other areas as well. There is only a slight reduction in the numbers of myelin lamellae for axons of a given size. The recovery of brain myelin and the incorporation of radioactive precursors into purified myelin proteins and lipids are all greatly reduced, leading to a comparatively severe reduction in the brain myelin concentration. The myelin composition is only slightly altered, possibly as a result of delay in its normal chemical maturation. The actual vulnerable period that produces a lasting myelin deficit is the early period that includes oligodendroglia cell proliferation, whereas undernutrition restricted to a later period that includes the actual peak of myelin does not cause a lasting reduction in the brain myelin concentration. The belief that stunting the postnatal proliferation of oligodendroglia largely accounts for the myelin effect has not been substantiated by direct analysis of cell numbers. Consequently, the observed hypomyelination likely results from a failure of oligodendroglia to mature and to initiate myelin formation. The myelin deficit appears largely uniform throughout the brain. Indirect evidence in human studies indicate that comparable effects appear in undernourished infants.

Animals↗
PubMed1982

Brain maturation following administration of phenobarbital, phenytoin, and sodium valproate to developing rats or to their dams: effects on synthesis of brain myelin and other subcellular membrane proteins.

The anticonvulsant drugs phenobarbital, phenytoin, sodium valproate, and phenytoin-sodium valproate in combination were administered daily to (a) pregnant rats starting on the 5th day after conception, and continued through 17 days postpartum, or (b) to developing rats between 3 and 17 days of age. Each drug was prepared in water and administered at either a therapeutic dose (TD), three times therapeutic dose (3TD), or 9TD. Drug administration had no discernible effect on litter size or sex ratio in the offspring; however, phenobarbital administration to dams caused small but significant reductions in birth weights. Body weights of developing rats treated with anticonvulsant drugs either via dams of directly by intraperitoneal injection lagged behind controls. At 20-24 days of age the brain weights of the offspring of phenobarbital (9TD)-exposed dams lagged control weights by 5% whereas brain weights in the offspring of the other treated groups were indistinguishable from controls. In contrast, administration of phenobarbital directly to developing rats caused no significant brain weight deficits whereas significant deficits were observed with phenytoin (9TD), sodium valproate (9TD), and phenytoin-sodium valproate (9TD) in combination. AT 20-24 days of age the relative incorporation of radioactive leucine into purified myelin and crude nuclear proteins of drug-treated rats or the offspring of drug-treated dams was reduced by 10-20% in all cases. Dose-related differences were not observed however, and the effects of phenytoin and sodium valproate in combination approximated those of phenytoin administered alone.

Animals↗
PubMed1981

A possible effect of the methylxanthines caffeine, theophylline and aminophylline on postnatal myelination of the rat brain.

A double isotope methodology was used to assess the effect of methylxanthine administration on membrane protein synthesis in developing rat brain. Rat pups were given either aminophylline, theophylline, or caffeine in a dosage of 40 mg/kg or 80 mg/kg daily from the second postnatal day through 20 days of age. Results show depressed myelin protein synthesis at 21.24 days by theophylline (80 mg/kg) and caffeine (40 and 80 mg/kg). Synthesis was essentially normal at 27-28 days of age, indicating a possible delay in development followed by a 'catch-up' phenomenon.

Aging↗
PubMed1981

Chemotactic activity generated from the fifth component of complement by plasma kallikrein of the rabbit.

Rabbit plasma kallikrein incubated with rabbit C5 resulted in the generation of chemotactic and secretagogue activity for rabbit neutrophils. This effect on C5 appeared to be due to kallikrein itself and not to a contaminating enzyme, because it could be inhibited by anti-kallikrein IgG or by soybean trypsin inhibitor to the same extent the kinin generation by the same kallikrein preparation was inhibited by these agents. The chemotactic response was consistent with the generation of a C5a-like peptide from C5 because the effect could be partially inhibited by carboxypeptidase N and was related to the generation of a small (approximately 14,000 mol wt) fragment of C5. No direct chemotactic response was detectable for kallikrein, activated Hageman factor, high-molecular weight kininogen, or intact C5. Incubation of Kallikrein, high-molecular weight kininogen, and Hageman factor together, so that activation of all three proteins occurred, did not results in the generation of detectable chemotactic activity.

Animals↗