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Biomedical subjects

C R Anderson

Publications and source records attributed to C R Anderson.

At least 19 recordsLinked to original sources
PubMed1992

NADPH diaphorase-positive neurons in the rat spinal cord include a subpopulation of autonomic preganglionic neurons.

Preganglionic neurons in the spinal cord of the rat were labelled retrogradely with Fluoro-gold and the spinal cord stained for NADPH diaphorase. The majority of both sympathetic and sacral parasympathetic preganglionic neurons showed staining for NADPH diaphorase. NADPH diaphorase-positive neurons were located more laterally in the intermediate zone than were preganglionic neurons lacking NADPH diaphorase staining. The recent evidence that identifies NADPH diaphorase as nitric oxide synthase raises the possibility that some spinal preganglionic neurons may synthesize nitric oxide.

3,3'-Diaminobenzidine↗
PubMed1992

The mechanism and significance of pentagastrin-stimulated water intake in the pig.

The role of gastric secretion in drinking was investigated. Treatment of pigs with cimetidine (300 mg IV), which inhibits gastric secretion, did not change the level of feed or water intake, or alter the temporal relationship between eating and drinking. Gastric infusions of 0.15 M HCl (5 ml.kg-1.h-1) did not increase drinking. Pentagastrin infusion (0.05 microgram.kg-1.min-1) increased water intake in some, but not all pigs during a 1-hour infusion. Plasma protein levels increased significantly during 1-hour pentagastrin infusions (0.05 microgram.kg-1.min-1), indicating an estimated fall in blood volume of 2.5%. Captopril (1.75 mg/kg IV), which blocks the renin-angiotensin system, abolished pentagastrin-stimulated drinking. It was concluded that gastric secretion does not play a direct role in normal, periprandial drinking but that in pigs the renin-angiotensin system is involved in pentagastrin-stimulated drinking.

Animals↗
PubMed1992

Animal bites. Guidelines to current management.

Several factors need to be considered when evaluating animal bites. These include type of animal involved, specific nature of the wound, circumstances of the attack, interval between injury and treatment, and location of the bite. Of concern are direct destruction of tissue and risk of infection. Use of antibiotic prophylaxis is controversial, but most authorities agree that it is needed for hand wounds, puncture wounds, or "dirty" wounds of any type in any location. The choice of antibiotic is also controversial, but initial empirical treatment generally relies on broad-spectrum coverage. Rabies prophylaxis is indicated for bites by carnivorous wild animals, bats, and unvaccinated domestic animals. Review of the patient's tetanus status is mandatory.

Animals↗
PubMed1992

Electrophysiological responses in the rat tail artery during reinnervation following lesions of the sympathetic supply.

1. Responses to perivascular stimuli have been recorded with intracellular microelectrodes from the smooth muscle of isolated segments of the main caudal artery of rats at various times between 7 and 128 days after all four collector nerve trunks had been lesioned near the base of the tail at 21 days of age. 2. In proximal segments (< 40 mm distal to the lesions), excitatory junction potentials (EJPs) and neurogenic alpha-depolarizations (NADs) evoked by stimuli presented via a proximally located suction electrode were similar to those in the same segments of unoperated control animals of the same age. Supramaximal EJPs in these segments decreased in amplitude with age. 3. Stimuli just supramaximal for EJPs in innervated preparations failed to evoke responses in segments farther than 30-40 mm distal to the lesions at any time after the nerves had been cut and 1 cm excised. Higher voltages evoked slow depolarizing potentials (SDPs) which were of longer time course than EJPs. Similar responses occurred in segments over 60 mm distal to the lesions at 20-50 days after the nerves had been frozen, and in all segments sampled over 100 mm distal to nerve lesions. 4. Spontaneous transient depolarizations (STDs) were recorded at all depths of the media in denervated segments. These occurred at frequencies similar to those of spontaneous events (including attenuated spontaneous EJPs) in innervated segments. 5. The earliest signs of reinnervation (24-42 days after freeze lesions) consisted of very small amplitude EJPs of normal time course which facilitated markedly during a short train of stimuli (5-10 Hz); these were followed by NADs which were large relative to the amplitudes of the EJPs. Less commonly, small focal EJPs of brief time course (resembling spontaneous EJPs in superficial cells of innervated arteries) were evoked in very restricted regions of the vessel wall. 6. At later times (57-128 days postoperative), six of eight segments located 40-70 mm distal to freeze lesions showed EJPs of nearly control amplitude, but NADs that were larger than in equivalent segments from control animals. In the remaining two cases, reinnervation at this level was similar to that seen at the earliest postoperative times. High stimulus voltages prolonged the decay of EJPs in both control and reinnervated arteries. 7. Sensitivity to exogenous noradrenaline, assessed in terms of membrane depolarization, was increased in both denervated and reinnervated segments. 8. Catecholamine fluorescence disappeared from the arteries at a distance greater than 30-40 mm distal to the site of the nerve lesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic Fibers↗
PubMed1992

Cloning and nucleotide sequence of the gene coding for citrate synthase from a thermotolerant Bacillus sp.

The structural gene coding for citrate synthase from the gram-positive soil isolate Bacillus sp. strain C4 (ATCC 55182) capable of secreting acetic acid at pH 5.0 to 7.0 in the presence of dolime has been cloned from a genomic library by complementation of an Escherichia coli auxotrophic mutant lacking citrate synthase. The nucleotide sequence of the entire 3.1-kb HindIII fragment has been determined, and one major open reading frame was found coding for citrate synthase (ctsA). Citrate synthase from Bacillus sp. strain C4 was found to be a dimer (Mr, 84,500) with a subunit with an Mr of 42,000. The N-terminal sequence was found to be identical with that predicted from the gene sequence. The kinetics were best fit to a bisubstrate enzyme with an ordered mechanism. Bacillus sp. strain C4 citrate synthase was not activated by potassium chloride and was not inhibited by NADH, ATP, ADP, or AMP at levels up to 1 mM. The predicted amino acid sequence was compared with that of the E. coli, Acinetobacter anitratum, Pseudomonas aeruginosa, Rickettsia prowazekii, porcine heart, and Saccharomyces cerevisiae cytoplasmic and mitochondrial enzymes.

Amino Acid Sequence↗
PubMed1991

The release of neuronal 5-HT from the intestine of a teleost fish, Platycephalus bassensis.

The superfused, isolated intestine of a teleost fish which lacks enterochromaffin cells spontaneously released 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), presumably from enteric neurons. The release of 5-HT, but not 5-HIAA, increased on transmural electrical stimulation. Addition of tetrodotoxin or omission of Ca2+ from the superfusate prevented the increase in 5-HT release on electrical stimulation. Fluoxetine added to the superfusate increased the amount of 5-HT released spontaneously but also prevented the increase in 5-HT release on stimulation. Pretreatment of fish with reserpine markedly reduced tissue levels of 5-HT and 5-HIAA and led to an almost complete loss of the spontaneous release of 5-HT and an elimination of the stimulated release of 5-HT.

Animals↗
PubMed1991

The time course of the development of the sympathetic innervation of the vasculature of the rat tail.

The development of the sympathetic innervation of the tail vasculature in the rat has been examined using catecholamine fluorescence and immunohistochemical techniques to demonstrate tyrosine hydroxylase (TH) and neuropeptide Y (NPY). The tail was found to be largely devoid of noradrenergic terminals at birth. At the earliest ages, axons within nerve trunks and paravascular axon bundles showed high levels of catecholamine fluorescence, but this virtually disappeared as the innervation of the effectors was achieved. The perivascular plexus on the caudal artery was established over the first six postnatal weeks along a rostrocaudal gradient which was retained in the adult, i.e. proximal regions were more densely innervated than distal ones. The innervation of the rest of the vasculature developed relatively late during this period, with the exception of the arteriovenous anastomoses present in the distal half of the tail. These became innervated about 10 days earlier than the adjacent caudal artery at the same levels, and received a much denser innervation in the adult. At all developmental stages, distributions of TH- and NPY-immunoreactive nerve fibres were identical to those seen with catecholamine fluorescence. The sequence of development suggests that the different vascular targets are innervated by subsets of sympathetic neurons having the same neurochemistry but developing independently.

Animals↗
PubMed1990

The effects of mercuric chloride on calmodulin-mediated Ca2+ transport in rat brain.

We have shown previously that mercuric chloride (HgCl2) inhibits in vitro vasopressin release from the isolated rat neurohypophysis with maximum inhibition occurring with 0.5 mM HgCl2. Associated with the inhibition of hormone release is an increase in 45Ca+2 uptake, an increase in cytosolic 45Ca+2, and a reduction of 45Ca+2 accumulation by mitochondria in the intact gland. In the present series of studies, the effect of HgCl2 on calmodulin (CM) function in neural tissue preparations is reported. Mercuric chloride (0.5 mM) reduced 45Ca+2 binding to CM purified from bovine neurohypophyses by 20% and inhibited endogenous CM-stimulated Ca,Mg-ATPase activity from rat brain mitochondria in a dose-dependent fashion. Ca,Mg-ATPase activity was inhibited by 50 and 80% with 0.5 and 5.0 mM HgCl2, respectively. CM-stimulation of Ca,Mg-ATPase activity was inhibited by calmidazolium (CMZ) with maximal inhibition seen with 0.1 mM CMZ. Reversibility of the HgCl2 interaction with CM was demonstrated using CM-stimulated phosphodiesterase (PDEase) activity from rat brain. HgCl2 inhibited both basal and CM-stimulated PDEase activity in a dose-dependent manner with maximum inhibition occurring with 1.0 mM HgCl2. Preexposure of CM to an inhibitory concentration (1.0 mM) of HgCl2 resulted in no loss of stimulatory PDEase enzyme activity. From these results, we conclude that HgCl2 reversibly interferes with 45Ca+2 binding to CM and also inhibits CM-regulated Ca+2 pumping enzyme systems in the neurohypophysis. The inhibition of vasopressin release from the intact gland in the presence of HgCl2 thus, may be associated with a disruption of calcium in the neurohypophysis.

Animals↗
PubMed1990

Quality of life and rehabilitation differences among four end-stage renal disease therapy groups.

This study investigates the quality of life of patients on alternative therapies for end-stage renal disease. The quality of life of 766 patients who experienced one of the following therapies for at least one year are compared: a successful transplant performed in the 1970's (N = 82), a successful transplant performed in 1980-1984 (N = 91), in-center hemodialysis (N = 83, 8 centers), and continuous ambulatory peritoneal dialyses (CAPD) (N = 510, 185 centers). All patients were aged 19-56 and nondiabetic. Survey questionnaires were administered containing measures of physical, emotional and social well-being, vocational rehabilitation, and sexual adjustment. Case-mix differences were controlled, insofar as possible, with an Analysis of Covariance; adjusted means were compared. Findings indicate that the quality of life for successful transplant patients exceeds that of both dialysis groups for almost all variables (p less than 0.05 for 9/11 measures). This advantage persists when transplant patients are compared to dialysis patients who have experienced no prior, failed therapies.

Adolescent↗
PubMed1978

Glutamate current noise: post-synaptic channel kinetics investigated under voltage clamp.

1. Analysis of voltage-clamped noise has been used to investigate the operation of glutamate receptors and associated channels at the locust nerve-muscle junction. Channels opened by glutamate and an agonist have been compared. 2. Glutamate-induced current fluctuations have a power spectrum with a single (1/frequency2) component which fits a simple model for the operation of channels. The form of the spectra for glutamate voltage noise and for 'background' noise has been determined. 3. The single channel conductance was estimated from the spectra, gamma glutamate = 122 +/- 0.4 (S.E.) pS. This estimate is independent of membrane potential and of the amplitude of membrane current change produced by glutamate. 4. The rate constant, alpha, for the closing of glutamate-operated channels depends exponentially on membrane potential, conforming to the equation alpha = approximately alphaeetaVm (approximately alpha = 0.26 +/- 0.014 msec-1, eta = 0.0054 +/- 0.001 msec-1); the duration of the channel lifetime (tau) decreases with hyperpolarization. Membrane potential dependence of alpha reduces as temperature is lowered. 5. For glutamate-operated channels, the temperature dependence of alpha and gamma fits the Arrhenius equation; alpha and gamma decrease exponentially as a function of T-1 (degrees K) with a descrete change in slope at about 6 degrees C, indicating a change in the activaiton energies of the respective rate processes. 6. Spectra of quisqualate-induced current fluctuations have the same form as spectra for glutamate noise. The single channel conductance was estimated from the spectra, gamma quisqualate = 120 +/- 3.9 (S.E.) pS. 7. The rate constnt, alpha, for the closing of quisqualate-induced channels depends exponentially on membrane potential. The duration of the open state for quisqualate channels was 2.2 times longer than for glutamate channels. 8. For glutamate receptors the voltage-sensitivity of the channel life-time is in the opposite direction to that of ACh receptors in vertebrate muscle. Possible explanations for the sharp change in the activation energy of the rate processes associated with the channel are discussed.

Alanine↗
PubMed1976

Light-weight RTV silicone for maxillofacial prostheses.

Weight is a problem in retention of large skin-textured maxillofacial prostheses. The purpose of this investigation was to test the feasibility of mixing foam RTV silicone rubber with conventional RTV silicone rubber to obtain a light-weight material. Various mixtures of foam and conventional silicone rubber were formulated and tested for strength, accuracy of molding, color application, color stability, and texture. A special flask to support the mold was necessary in order to overcome expansion problems associated with gas formation of the foam silicone rubber. The mold required venting to release the gas and to reduce the expansion of the prosthesis in order to maintain accuracy. Molding, accuracy, texture, and color problems were overcome. Reduction of weight proportionate to reduction of tear strength of the material formulated, however, did not allow routine use of mixtures of foam and conventional silicone. When the weight of a prosthesis is critical and excessive and thickness is sufficient to give adequate strength, the foam and conventional silicone mixture can be used.

Color↗