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Biomedical subjects

C R Anderson

Publications and source records attributed to C R Anderson.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1988

Quality of life after kidney transplantation. A prospective, randomized comparison of cyclosporine and conventional immunosuppressive therapy.

The aim of this research is to compare the quality of life after kidney transplantation for patients treated with cyclosporine versus conventional immunosuppressive therapy. This evaluation assumes particular importance given the high cost of cyclosporine, the resistance of the government to cover these costs, and the absence in some series (including this one) of significant differences in patient and kidney survival. This study is based on a randomized, stratified, prospective trial and concentrates on nondiabetic patients from ages 19 to 56 at 1-year posttransplant. Patients on cyclosporine show significant advantages in physical, emotional, and social well-being. Differences for 5 out of 10 indicators of quality of life were significant at the P less than or equal to .05 level. Significant differences are found on health satisfaction, happiness measures, indices of overall life satisfaction and well-being, perceived adjustment of the family, and female (not male) vocational rehabilitation. The fewer number of episodes of rejection and infection are, in part, responsible for these advantages in quality of life for cyclosporine patients.

Actuarial Analysis↗
PubMed1987

The relationship of terminals containing neuropeptide Y-like immunoreactivity to lumbar sympathetic vasoconstrictor neurones in the rabbit.

The distributions of preganglionic neurones retrogradely labelled with horseradish peroxidase and of immunohistochemically identified varicose axons reactive for neuropeptide Y (NPY-IR) in the intermediate zone of rabbit lumbar spinal segments have been compared. Neurones projecting in the caudal lumbar sympathetic chain (LSC), which are mainly vasoconstrictor, were located laterally, associated with dense accumulations of NPY-IR terminals in mid L3 to caudal L4. In all other regions of the lumbar intermediate zone, there was relatively little correlation between the location of either LSC neurones, or those projecting to the pelvic viscera, and aggregations of NPY-IR axons. Most of these axons probably arise in the C1 nucleus, but it seems possible that this nucleus innervates only some groups of lumbar vasoconstrictor neurones.

Animals↗
PubMed1985

Effect of photoperiod on milk yield and milk fat in commercial dairy herds.

Two hundred and sixteen cows stanchioned in 13 dairy herds were exposed to supplemental lighting of 16 to 16.25 h of light per day from fluorescent lamps, whereas 240 herdmates received only sunlight (9 to 12 h/day) plus lighting for usual management activities (e.g., milking and feeding). After adjustment for differences in stage of lactation, lactation number, mature equivalent, and pretrial milk yield, cows exposed to supplemental lighting produced 2.2 kg per day more milk and had .16% less milk fat than herdmate controls.

Animals↗
PubMed1985

Selecting for lactation curve and milk yield in dairy cattle.

Knowledge of genetic relationships between characteristics of lactation curves and lactation yields is essential for joint selection for both. An equation, yt = atbexp(-ct), was chosen to depict individual lactation curves for 5,927 first lactations by Holsteins in 557 herds in Michigan Dairy Herd Improvement where yt is daily milk yield at day t in lactation, a is yield at time zero, b is ascent to peak, and c is decline after peak. Genetic correlations for 305-day milk yield with initial production (a), ascent to peak (b), descent after peak (c), and peak yield were -.37, .40, 0, and .91. From empirical results from applied selection indexes, selecting for both increase of ascent to peak and peak yield did not decrease 305-day milk substantially. Rankings of sires on these indexes were similar to their rankings on milk yield alone. Attempts to decrease peak yield and increase persistency decreased milk yield greatly.

Age Factors↗
PubMed1980

Susceptibility of two turtle species to eastern equine encephalitis virus.

Two species of turtle collected in southern New England were inoculated subcutaneously with eastern equine encephalitis virus. The spotted turtles (Clemmys guttata) developed viremia and neutralizing antibody after exposure to 3 logs or more of virus. Viremia was not detected in the eastern painted turtles (Chrysemys picta), and neutralizing antibody was detected in only 1 of 15 inoculated C. picta; however, since pre-inoculation serum was not obtained from this animal, the possibility of natural infection cannot be eliminated.

Alphavirus↗
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↗