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

Spontaneous drinking: is it stimulated by hypertonicity or hypovolemia?

Ten young female pigs were allowed to eat and drink whenever they wanted, and blood samples were taken without disturbance to the pig. Samples were divided into four categories: 1) base line, i.e., taken when not drinking and not eating; 2) preprandial, i.e., taken when starting to drink just before eating; 3) postcibal, i.e., taken when starting to drink after any eating; and 4) nonprandial, i.e., taken when starting to drink but not in association with eating. Osmolality (mosmol/kgH2O), plasma protein (g/dl), and packed cell volume (%) were, respectively, as follows (mean +/- SE): base line 294.9 +/- 1.8, 6.2 +/- 0.1, and 30.0 +/- 1.2; preprandial 295.1 +/- 1.7, 6.1 +/- 0.2, and 29.7 +/- 1.4; postcibal 295.0 +/- 3.3, 6.5 +/- 0.2, and 31.7 +/- 1.3; and nonprandial 295.2 +/- 1.4, 6.3 +/- 0.1, and 30.0 +/- 1.3. None of the parameters associated with drinking were significantly different from base-line parameters, except for the postcibal rise of packed cell volume. Calculated blood volume differences from base line were as follows: preprandial 0.7 +/- 1.2% fall; postcibal 0.2 +/- 1.7% increase; and nonprandial 0.8 +/- 0.9% fall. It is unlikely that either plasma hypertonicity or hypovolemia stimulates drinking under spontaneous conditions.

Animals↗

PubMed1990

Hypertonic and hypovolemic stimulation of thirst in pigs.

Young female pigs weighing from 15 to 45 kg were used. Plasma osmolality was slowly raised by an intravenous infusion of 15% NaCl. The behavioral threshold was when the pigs began to drink water, and the rise of osmolality was the stimulus. In 23 measurements on 8 pigs the rise of osmolality to initiate drinking was 10.4 +/- 1.4 mosmol/kg (mean +/- SE). There was also an estimated 3.8 +/- 1.4% rise of blood volume. Control infusions of 0.9% NaCl for 1 h usually resulted in no drinking, and plasma osmolality fell by 6.7 +/- 2.1 mosmol/kg, while blood volume did not change. Hypovolemia was effected using furosemide (1 mg/kg body wt) to cause excretion of nearly isotonic urine. Blood volume changes were estimated from plasma protein and packed cell volume data. In 28 measurements on 6 pigs, drinking occurred when blood volume had decreased by 6.7 +/- 1.8%. During 2-h control periods, blood volume did not change appreciably. Plasma osmolality decreased during both the furosemide treatment (by 3.5 +/- 0.7 mosmol/kg) and the controls (by 4.1 +/- 0.8 mosmol/kg).

Animals↗

PubMed1990

Milk production and somatic cell count in Michigan dairy herds.

The established association between milk production and SCC in dairy cattle is increasingly used to estimate lost production due to mastitis. Such cost estimates are used to make decisions regarding cost effective mastitis prevention and control. It is therefore important to verify the relationship between SCC and milk production using data from different areas of the country and by using different analytical methodology. Our study used the 1985 to 1986 Michigan DHIA data base and analyzed daily milk production records rather than lactation summary records as used in the past. One advantage to our approach was that it did not give equal weight to all lactations, regardless of their duration. Also, it enabled inclusion of cows that had incomplete lactations caused by culling, or had other reasons for removal from the herd. A statistical model was constructed to predict milk production on the basis of herd, cow within herd, stage in lactation, month of calving, lactation, and SCC. The data base contained 397,172 milk test records obtained from Michigan DHIA from 504 Holstein herds in Michigan's lower peninsula. Our final model predicted 78% of the variation in milk production. Prediction of milk loss for each herd was highly correlated (r = .98) with the prediction model adopted by most DHIA organizations. Our model predicted that the mean herd lost a mean of 1.17 kg of milk/cow per d associated with SCC.

Age Factors↗

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↗

PubMed1989

Importance of spinal noradrenergic pathways in cardiovascular reflexes and central actions of clonidine and alpha-methyldopa in the rabbit.

We have examined in conscious rabbits the chronic effects of 6-hydroxydopamine (6-OHDA)-induced local lesions of the spinal noradrenaline (NA) pathways on (i) resting mean arterial pressure (MAP) and heart rate (HR), (ii) the nasopharyngeal pressor response, (iii) the sympathetic component of the baroreceptor-heart rate reflex (iv) the acute responses to intracisternal (i.c.) clonidine and alpha-methyldopa (alpha-MD), and (v) the acute NA release response produced by i.e. 6-OHDA. One month after injection of 6-OHDA (40 nmol in 4 microliters) into the first cervical spinal cord segment (C1), the NA content was reduced to 29% in C2, 45% in T4 and 61% in L3 with little non-specific damage. Basal MAP was 14% higher (P less than 0.05) than in sham-operated rabbits suggesting increased vasoconstrictor tone. Basal cardiac sympathetic tone was enhanced, but a corresponding increase in cardiac vagal tone resulted in little net effect on resting HR in the spinal NA-depleted group. Spinal NA lesions attenuated the nasopharyngeal pressor reflex by 27% in baroreceptor-intact rabbits and by 38% in sino-aortically denervated (SAD) animals. The lesion did not affect HR range, gain and BP50 of the sympathetic baroreflex. In SAD rabbits, the acute MAP responses to i.c. 6-OHDA (early hypotension, late hypertension) were not affected by spinal NA depletion, but the early fall in HR (cardiac sympathetic inhibition) was abolished. The hypotension produced by i.c. clonidine or alpha-MD was not affected by the lesion, probably because many of the NA terminals in the lower thoracic and upper lumbar cord were still intact. Our results suggest that intraspinal NA fibers have a tonic inhibitory action on spinal preganglionic vasoconstrictor and cardiac motoneurons. The spinal NA neurons affecting vasomotor tone (but not cardiac sympathetic tone) are in turn inhibited by higher vasomotor centers receiving projections from the arterial and trigeminal afferents and thereby participate in vasoconstrictor reflexes.

Animals↗

PubMed1989

Distribution of sympathetic preganglionic neurons and monoaminergic nerve terminals in the spinal cord of the rat.

A study was made of the distribution of sympathetic preganglionic neurons identified by retrograde labeling with horseradish peroxidase from various peripheral nerve trunks and of the distributions of monoaminergic terminals in the spinal cord of the rat. Nerve terminals were stained immunohistochemically by using antisera raised against tyrosine hydroxylase, phenylethanolamine-N-methyl-transferase, neuropeptide Y, and 5-hydroxytryptamine and by using formaldehyde-induced fluorescence. The three-dimensional distribution of sympathetic preganglionic neurons was described by using computer reconstruction and compared with the arrangement of each population of immunohistochemically stained terminals in the intermediate zone. Although monoaminergic terminals are associated with most sympathetic neurons, particularly in the intermediolateral column, the relationship of many terminals to sympathetic neuron somata in other parts of the intermediate zone is tenuous. Some of the descending innervation may terminate on interneurons. The data are consistent with the coexistence of phenylethanolamine-N-methyl-transferase and neuropeptide Y in terminals arising from cell bodies in the C1 region in the ventrolateral medulla and with the presence of at least two populations of catecholaminergic terminals as well as the adrenergic one. Serotoninergic terminals are denser and have a different arrangement from those of catecholaminergic terminals in the intermediate zone.

Animals↗

PubMed1989

Are there bulbospinal catecholaminergic neurones in the guinea pig equivalent to the C1 cell group in the rat and rabbit?

The C1 cell group in the rat is characterized by neurones which contain both adrenaline and phenylethanolamine-N-methyltransferase, and usually also neuropeptide Y (NPY). The former two substances are lacking in Guinea pig brainstem and spinal cord. We have examined the distribution of NPY- and tyrosine hydroxylase-immunoreactivity in the ventrolateral medulla and thoracolumbar intermediate zone of Guinea pig, as well as the distribution of catecholamine-containing neurone somata and spinal terminals visualized after formaldehyde-glutaraldehyde fixation. The results are compared with comparable immunohistochemical data obtained from rats and rabbits. Catecholaminergic neurones in the Guinea pig with locations and terminations that correspond to those of the C1 cell group in rat and its analogue in the rabbit appear to consist of two subgroups, with only the more caudal group containing NPY. The more rostral group requires pretreatment with monoamine oxidase inhibitor to permit visualization of catecholamine fluorescence, a property previously though to be characteristic of adrenergic neurones. This observation raises the possibility that the catecholaminergic cell group in the C1 region of rabbits may not contain adrenaline either.

Animals↗

PubMed1989

Metabolic origins of 5-hydroxytryptamine in enteric neurons in a teleostean fish (Platycephalus bassensis), a toad (Bufo marinus) and the guinea-pig.

1. 5-Hydroxytryptamine (5-HT) content and synthesis in mucosa-free intestine of guinea-pig, the teleost Platycephalus bassensis and the amphibian Bufo marinus was studied by HPLC with electrochemical detection or by TLC. 2. The 5-HT content of small intestine was: guinea-pig 0.58; Bufo: 1.23; Platycephalus: 26.88 nmol/g. 3. Intestine from each species synthesized 5-HT from exogenous 5-HTP. 4. Platycephalus preparations synthesized labelled 5-HT from 14C-tryptophan, but no labelled 5-HT was detected after similar incubation of guinea-pig or Bufo preparations. 5. Incubation of guinea-pig preparations with tryptophan did not increase tissue 5-HT or 5-HIAA content. 6. 5-HT in Platycephalus enteric neurons may be synthesized from tryptophan in situ; 5-HT in Bufo and guinea-pig neurons may be synthesized elsewhere, perhaps in enterochromaffin cells.

Animals↗

PubMed1989

Dietary therapy in gastrointestinal disease.

Diet therapy is an important factor in overall care of most GI patients. Historically, diets have been used unscientifically in many of these patients without positive results. Nutritional care and diet therapy are critical for two reasons. First, malnutrition is an expected sequelae to most, if not all, GI diseases or disorders. Failure to eat, digest, or assimilate nutrients can provoke malnutrition in just a few weeks, although careful assessment of anthropometric, clinical, biochemical, and nutritional history by a trained professional can protect against this. Diet therapy through the elimination of offending foods such as wheat gluten or lactose, or inclusion of specialized products such as medium chain triglycerides or elemental formulas, can sustain nutritional status. Dietary components such as insoluble fiber appear to have physiologic effects, while soluble fibers may have metabolic effects important to diabetes and cardiovascular disease. There is a high potential for malnutrition in Crohn's disease during active and remittent phases. Elemental enteral formulas or TPN are used during the active phase to ensure optimal nutritional status and bowel rest. Hyperalimentation using the GI tract during remittent stage maintains this. Avoiding offending foods by Crohn's patients is an acceptable practice as long as entire categories of foods are not deleted. Avoiding all foods containing gluten from wheat, rye, barley, and oats, however, is a crucial prerequisite to recovery from celiac disease. Gluten is commonly used as a stabilizer, emulsifier, and extender in the food industry and is not always shown on food labels. Careful consultation with a registered dietitian can identify hidden sources of gluten in the diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastrointestinal Diseases↗

PubMed1988

Is phenylethanolamine-N-methyltransferase (PNMT) contained in rat hypothalamic neurons?

Three polyclonal antisera raised against bovine adrenal phenylethanolamine-N-methyltransferase (PNMT) were used to stain PNMT-containing neurons in rat medulla oblongata and hypothalamus. Without colchicine pretreatment all three antisera stained nerve fibres in both the medulla and hypothalamus and nerve cell bodies in the medulla only. In colchicine pretreated rats one antiserum only stained cell bodies in the hypothalamus as well. All staining was prevented by prior absorption of the antiserum with purified bovine PNMT. Thus, if PNMT is present in the rat hypothalamic neurons then it is not identical to the form of PNMT present in rat medullary neurons.

Animals↗