Search PubMed⌕ Search

Biomedical subjects

R W Russell

Publications and source records attributed to R W Russell.

At least 73 records · Page 4Linked to original sources
PubMed1985

Cerebral and retinal vascular changes in systemic lupus erythematosus.

A 16-year-old white boy with acute systemic lupus erythematosus (SLE) who presented with chorea and florid retinopathy died in renal failure three months after diagnosis. Pathological studies revealed two types of lesion in both the cerebral and ocular vessels. Some meningeal and choroidal vessels showed a typical vasculitis with fibrinoid necrosis, whereas other meningeal and retinal vessels were occluded by amorphous hyaline material in the absence of vasculitis.

Adolescent↗
PubMed1985

Changes in presynaptic release of acetylcholine during development of tolerance to the anticholinesterase, DFP.

The rat myenteric plexus was used as a peripheral model for studying muscarinic modulation of acetylcholine (ACh) release from presynaptic muscarinic neurons during development of tolerance to the anticholinesterase agent, diisopropylfluorophosphate (DFP). DFP in arachis oil was administered subcutaneously to intact animals according to both acute and chronic regimens, with arachis oil injections serving as controls. Post-mortem analyses showed that the mean AChE activity level in whole brain was reduced under all DFP conditions to 18.0 +/- 1.4% when compared with the control level. After 10 days of DFP treatment, the AChE level was 22.3 +/- 2.1% of control in the myenteric plexus. There were no significant differences among the treatment groups in resting ACh release. Release evoked by electrical stimulation (difference between stimulated and resting release) in the absence of atropine, i.e., "basal rate," for strips taken at various times after a single injection of DFP did not differ from that for strips from animals receiving arachis oil only. However, basal release for strips from chronically treated subjects was significantly greater than that of controls (p less than 10(-3), although not different from each other. Analysis of variance (ANOVA) for repeated measures showed that there existed a highly significant atropine dependency in strips from all treatments when they were stimulated in concentrations of atropine from 10(-9) to 10(-5) M (p less than 10(-10). Further analyses established that the increases in rates of evoked ACh release as concentrations of atropine increased were similar for strips from chronically treated DFP and arachis oil animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1985

Effects of feeding whole cottonseed to lactating dairy cows on glucose and palmitate metabolism.

Eight lactating Holstein dairy cows were fed corn silage-based diets with or without whole cottonseed at 18.5% of the dietary dry matter. At 42 days postpartum, a pulse injection of 100 mg glucose/kg body weight was given intravenously and plasma glucose concentration was monitored for 45 min. At 50 d postpartum, biopsies of adipose tissue and mammary tissue were taken and tissue slices were incubated in vitro with either uniform carbon-14 glucose or 1-carbon-14 palmitate. Basal concentration of plasma glucose was not affected by diet, although apparent distribution volume of glucose did seem to decrease due to feeding whole cottonseed. Feeding whole cottonseed decreased uptake of glucose and palmitate in both adipose tissue and mammary tissue and also decreased oxidation of glucose to carbon dioxide in both tissues. Palmitate oxidation was not affected by diet. Incorporation of carbon-14 from glucose into adipose tissue lipids was decreased in cows fed whole cottonseed. Results indicate that fat supplementation in the form of whole cottonseed may decrease palmitate incorporation and glucose utilization for glycerol and reducing equivalent synthesis in both adipose tissue and mammary tissue of lactating dairy cows.

Adipose Tissue↗
PubMed1985

Method for calculating digesta flow and apparent absorption of nutrients from nonrepresentative samples of digesta.

A mathematical method is presented for measuring net disappearance of nutrients as digesta traverses the digestive tract of animals equipped with simple cannulae. The method requires that each distinct phase of a sample be physically separated if this phase forms a different percentage of the sample than it does of the total digesta. In addition, the number of dietary markers used must equal the number of phases separated. Each marker is administered continuously and simultaneously. It is not required that markers associate completely with one phase. Transfer ("hopping") of markers among phases does not invalidate calculations provided that such transfer does not cause complete randomization. The solution is presented in matrix form to be adaptable to any number of digesta phases.

Animals↗
PubMed1984

Selective breeding for differences in cholinergic function: pre- and postsynaptic mechanisms involved in sensitivity to the anticholinesterase, DFP.

To determine the contribution of presynaptic cholinergic mechanisms to the increased sensitivity of a genetically selected line of Sprague-Dawley rats (Flinders S-line) to the anticholinesterase, diisopropyl fluorophosphate (DFP), rats were sacrificed by focused microwave irradiation of the head 1 min after a pulse injection of deuterium-labeled choline into the tail vein. The S-line rats exhibited higher concentrations of labeled acetylcholine (ACh) in the cortex than the rats bred for resistance to DFP (Flinders R-line). To determine the contribution of postsynaptic cholinergic mechanisms the concentration of brain muscarinic ACh receptors (mAChR) was determined. The S-line rats exhibited higher concentrations of striatal and hippocampal mAChR than the R-line rats. Thus, both pre- and postsynaptic cholinergic mechanisms may contribute to the increased sensitivity to DFP but their relative importance varies with brain region: increased ACh synthesis in the cortex and increased concentrations of mAChR in the striatum and hippocampus.

Acetylcholine↗
PubMed1984

The up-and-down method for the determination of nociceptive thresholds in rats.

The up-and-down method applied to the jump-flinch technique provided estimates of shock thresholds for jump and flinch with high statistical efficiency and a much reduced amount of experimentation compared with traditional methods. Reproducible results were obtained after repeated testing and flinch and jump thresholds were significantly increased by treatment with morphine or oxotremorine.

Animals↗
PubMed1984

Selective breeding for differences in cholinergic function: sex differences in the genetic regulation of sensitivity to the anticholinesterase, DFP.

Genetic factors involved in the sensitivity of behavioral and physiological variables to the anticholinesterase diisopropyl fluorophosphate (DFP) were studied by comparing the sensitivities to DFP of two lines of rats selectively bred to be either sensitive ( Flinders S-line) or resistant ( Flinders R-line) with F1 and F2 genetic crosses between the two lines. The dependent variables selected were body weight, core body temperature, and water intake. Statistical analyses with two-way ANOVA revealed highly significant line differences for all variables and significant sex differences for core body temperature and water intake. Among the lines and crosses the S-line was more sensitive, followed in order by the F2, F1 and R-line. However, the relative differences among the lines varied for the two sexes. The F1 males were almost identical to their R-line counterparts, whereas F1 females were intermediate between the female S- and R-lines. The data were also subjected to discriminant function analyses and similar relationships were found. Estimates of the number of genes involved in the inheritance of DFP sensitivity suggest a single gene in males and two genes in females. The data for the males were reasonably consistent with a model for a single recessive gene coding for DFP sensitivity. On the other hand, the data for the females could be fitted better with a two-gene model, although there was not a complete fit with the observed data. These results provide strong support for sex differences in the genetic regulation of DFP sensitivity.

Animals↗
PubMed1984

Pathological changes in small cerebral arteries causing occlusion and haemorrhage.

The resistance arteries of the brain contain relatively small amounts of muscle and elastic tissue. As a result of chronic hypertension, the small arteries develop microaneurysms at points of least resistance. Plasma leaking into the damaged wall leads to lipohyaline change. The end-result is either occlusion of the artery, causing a lacunar infarct, or rupture, causing intracerebral haemorrhage.

Age Factors↗
PubMed1984

Glucose kinetics, plasma metabolites, and endocrine responses during experimental ketosis in steers.

Phlorizin and 1,3-butanediol were used to determine effects of glucosuria and ketonemia on concentrations of metabolites in blood plasma and on kinetics of glucose metabolism. Four steers received four treatments (control; control plus dietary 1,3-butanediol; control plus phlorizin injections; and control plus phlorizin and 1,3-butanediol) in a Latin square design. Treatments lasted 14 days. All steers received a 30% grain, 70% forage ration in equal meals every 2 h. Metabolite concentrations in blood plasma and urine and glucose kinetics were measured on each of the last 3 days of each treatment period. Phlorizin caused glucosuria; decreased plasma glucose, glucose total entry rate, and glucose recycling; and increased plasma free fatty acids and glucose irreversible loss. Glucose pool size was increased by 1,3-butanediol. Phlorizin plus 1,3-butanediol caused glucosuria and ketonuria; decreased plasma glucose; and increased blood ketone bodies, plasma free fatty acids, glucose irreversible loss, and glucose pool size. Growth hormone, insulin, and glucagon were not affected by treatment. Physiological perturbations in these steers were characteristic of some of those in ketotic cows.

Acidosis↗
PubMed1983

Sex-linked and other genetic factors in the development of tolerance to the anticholinesterase, DFP.

Development of tolerance to the effects of the anticholinesterase, di-isopropylfluorophosphonate (DFP), on core body temperature, a simple operant drinking response, and an operant fixed ratio lever-press response has been studied in the males and females of the S14 and S15 generations of two lines of rats genetically selected for their differences in sensitivity to DFP. For temperature measurement, males and females of the Flinders-resistant line (R-line) developed tolerance quicker than did the males and females of the Flinders-sensitive line (S-line). For the operant drinking response, females of both lines were tolerant after the third injection, while resistant males were tolerant only after the seventh injection and sensitive males were not completely tolerant at the conclusion of the experiment. For the operant fixed ratio lever-press responding all groups were tolerant after the second injection. These findings indicate that the development of tolerance to DFP can be influenced by the genetic background, the sex of the organism and the nature of the behaviour being measured, suggesting that several mechanisms may underlie development of tolerance to this agent.

Animals↗
PubMed1983

Critical perfusion of brain and retina.

Four patients with extensive occlusive disease of the extracranial arteries are described. All suffered attacks of visual loss due to transient retinal ischaemia and all developed the haemorrhagic changes of low-flow retinopathy. Resting cerebral blood flow was within normal limits in all patients. The attacks were provoked by falls in systemic blood pressure or, in one patient, by facial heating. The probable mechanism in this last case is thought to be diversion of blood to a dilated external carotid vascular bed. Temporary cerebral and brachial symptoms occurred but no permanent changes developed. Successful surgical reconstruction was achieved in two patients with relief of symptoms.

Adult↗
PubMed1982

Selective breeding for diisopropyl fluorophosphate-sensitivity: behavioural effects of cholinergic agonists and antagonists.

The behavioral effects of cholinergic agonists and antagonists were examined in two lines of rats which have been developed through selective breeding techniques to be differentially sensitive to the anticholinesterase diisopropyl fluorophosphate (DFP). The line of rats which were determined to be more sensitive to DFP (Flinders S line) were also more sensitive to the depressant effects of the agonists pilocarpine and physostigmine on locomotor activity, water intake, and operant responding maintained by water reward. In contrast, the locomotor stimulant effects of scopolamine, a muscarinic antagonist, were less marked in the S-line rats, while the depressant effects of atropine and scopolamine on water intake and operant responding maintained by water reward were comparable in the two lines. The S-line rats were also significantly more sensitive to the hypothermic effects of pilocarpine and oxotremorine. These findings are consistent with the hypothesis that the S-line rats are more sensitive to the acute effects of DFP because they have a higher number of muscarinic-cholinergic receptors.

Animals↗
PubMed1982

Selective breeding for sensitivity to DFP: generalization of effects beyond criterion variables.

The degree of generalization to the effects of DFP, an organophosphate anticholinesterase, was studied in two lines of Sprague-Dawley derived rats selectively bred for varying sensitivities to DFP. In the S13, S14, S15, and S16 generations the Flinders S-line of rats were still more sensitive to the effects of DFP on the criterion variables upon which selection was based: core body temperature, body weight and a simple operant response for water reward. The flinders S-line were also more sensitive to the effects of DFP on locomotor activity, FR5 responding for a water reward, and analgesia, indicating some degree of generalization. However, diarrhea, a symptom of peripheral effects of DFP, occurred at a similar incidence in the two lines, although males of both lines had higher incidences than the females. Neither of the two lines was affected by DFP for variables in which aversive (i.e. shock) motivation was used: The number of discriminative escape responses and the escape times were similar. These findings indicate that while the effects of DFP do generalize beyond the criterion variables upon which selection was based, the generalization is relatively specific. The data are consistent with the hypothesis that the changes in sensitivity have arisen because of changes in the functioning of a central cholinergic system(s).

Animals↗
PubMed1982

Visual field defects in obstructive hydrocephalus.

Four cases are described in which visual field defects followed enlargement of the third ventricle. Three were due to aqueduct stenosis while in one case a left cerebellar hemisphere tumour was discovered. The visual field defects comprised a unilateral scotoma, bilateral scotomata and, in two patients, incongruous bitemporal hemianopia.

Adult↗