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J C Russell

Publications and source records attributed to J C Russell.

At least 127 records · Page 7Linked to original sources
PubMed1988

Use of the multiple uptake gated acquisition scan for the preoperative assessment of cardiac risk.

A retrospective study was undertaken at three hospitals of 196 patients who underwent an operative procedure as long as 60 days after radionuclide determination (multiple uptake gated acquisition scan [MUGA]) of left ventricular ejection fraction (LVEF). Cardiac related mortality rates were 2.2 per cent among patients in group 1, LVEF greater than or equal to 55 per cent; 5.4 per cent in group 2, LVEF 36 to 54 per cent, and 19.5 per cent in group 3, LVEF less than or equal to 35 per cent (p less than 0.005). Statistically significant correlation between MUGA-derived LVEF and cardiac related mortality was found in veteran patients undergoing noncardiac surgical procedures (both vascular and nonvascular). There was no correlation between MUGA-derived LVEF and postoperative cardiac related mortality in cardiac surgical patients. A preoperative American Society of Anesthesiologists Physical Status Evaluation classification of IV or a preoperative pulmonary capillary wedge pressure of 20 centimeters of water or greater also predicted an increased risk of postoperative cardiac death. We advise preoperative MUGA scans for all patients in whom the results of preoperative history or physical examination suggest compromised ventricular function. We also advise pulmonary arterial catheter hemodynamic monitoring during the perioperative period for all patients with a preoperative MUGA-derived LVEF of less than or equal to 35 per cent.

Adult↗
PubMed1987

Serum lipids and lipoproteins in the atherosclerosis prone LA/N corpulent rat.

The LA/N rat is one of two congenic strains bred from the original obese, hyperphagic and hypertensive rats of Koletsky. With the exception of hypertension the LA/N strain, when homozygous for the corpulent gene, is phenotypically similar to the parent Koletsky strain and prone to the development of vascular and myocardial lesions. Here we report a detailed analysis of the serum lipids, lipoproteins and apolipoproteins B, E and A-I levels in young adult homozygous corpulent (cp/cp) rats of both sexes and in lean males of the same age which were demonstrable non-carriers (+/+) of the cp gene. Both male and female cp/cp rats were hypertriglyceridemic (282-512 mg/100 ml) and moderately hypercholesterolemic (74-84 mg/100 ml). Elevations in these lipids reflected the presence of large (622 A), triacylglycerol-rich and apoprotein-poor VLDL containing both apolipoproteins Bh and B1 and increased phospholipid-rich HDL. Similar, but less pronounced, elevations in serum apolipoproteins B and E in the cp/cp rats when compared to the +/+ animals were also noted. Apolipoproteins A-I levels were 2.7-3-fold higher in cp/cp rats. The levels of VLDL were significantly higher in female cp/cp rats; however, the levels of IDL (intermediate-density lipoproteins), LDL and HDL were significantly lower than in the more atherosclerosis prone male cp/cp rats. Similarly, apolipoprotein A-I was higher and apolipoprotein B lower in the male cp/cp than in the female cp/cp rats. The LDL (d = 1.030-1.063 g/ml) in cp/cp rats, like that in normal animals, was heterogeneous and contained apolipoproteins Bh, E, A-I and C. This fraction was significantly elevated in male cp/cp rats when compared to females but still represented less than 13% of the total serum cholesterol and less than 6% of the total serum lipids in 3-month-old cp/cp animals. The ratio of cholesterol to phospholipids was significantly lower for all lipoproteins in cp/cp rats when compared to +/+ males and these ratios for female cp/cp rats were in all cases lower than those of male cp/cp animals.

Animals↗
PubMed1987

Enhancement of cold-stimulated thermogenesis in the corpulent rat (LA/N cp) by aminophylline.

Previous studies on obese strains of rats (e.g., Zucker and LA/N cp) have shown that they are deficient in nonshivering thermogenesis and poor in cold tolerance. Our earlier studies have established that aminophylline (AMPY; 85% theophylline-15% ethylenediamine) is effective in significantly improving cold tolerance in the lean Sprague-Dawley rat regardless of age or thermogenic capacity. The present study tested whether AMPY may be also effective in improving cold tolerance in both young (12-18 wk) and older (36-42 wk) lean and corpulent LA/N cp rats. Contrary to previous reports, however, the norepinephrine (NE)-stimulated nonshivering thermogenesis was not only present but also equal in magnitude in the corpulent rats to that of their lean controls. Further, no difference in cold tolerance was observed between the two groups regardless of age. Similarly, AMPY (18.7 mg/kg ip) significantly improved thermogenesis and cold tolerance in both lean and corpulent rats, again without any age-related difference in response. These results indicate that, despite the existence of obesity, no difference in thermogenic capacity to either NE or cold stimulation is evident in the LA/N cp rats. Thus the ontogeny of obesity in this strain may be caused by factors other than deficiency in NE- or cold-stimulated thermogenesis at the end-organ level.

Aminophylline↗
PubMed1987

Induction of voluntary prolonged running by rats.

The rat is widely used in studies of the metabolic and physiological effects of physical exercise. The most commonly used form of exercise is running on treadmills or mechanically driven running wheels. Rats will not voluntarily run significant distances, under normal circumstances. If rats are exposed to running wheels with food freely available, only very limited activity normally occurs. When rats with access to a running wheel are restricted to a fixed amount of food, presented once per day, consistent running occurs. The running is spontaneous and very sensitive to the amount of food provided. Six 6-wk-old rats of 197 g mean body wt were induced to run for 139 days. The distance run increased rapidly over a 20-day initial period on a food supply of 15 g/day (vs. 19.5 g/day consumption by sedentary controls). From day 20 to day 139 the mean distance run was described by the regression equation distance (m/day) = 10,410 - 37.9 X days. Food provided was varied according to distance run, ranging from 15 to 18 g/day, and was normally 17.5 g/day. Thus a food deprivation of 10% of normal consumption will result in mean distances run of approximately 8,000 m/day. The use of pair-fed control animals without access to a wheel allows the conduct of experiments to test the effects of chronic long-distance running. The running is spontaneous; thus the technique avoids the complications accompanying techniques that force running.

Animals↗
PubMed1987

A calibrated fluorescence polarization assay for assessment of fetal lung maturity.

The mechanism of a new fluorescence polarization method for measuring phospholipid in amniotic fluid is described. The fluorescence polarization of a surfactant fluorescent dye solubilized in amniotic fluid correlates significantly with the L/S ratio. Model studies indicate that this results primarily from partitioning of the dye between endogenous albumin, which causes a high fluorescence polarization, and dispersed phospholipid, which causes a much lower polarization. The fluorescence polarization can be compared with a calibration curve to give the ratio of phospholipid to albumin in the sample. This procedure may prove useful in antenatal assessment of fetal lung maturity.

4-Chloro-7-nitrobenzofurazan↗
PubMed1987

Age-related qualitative and quantitative changes in the endocrine pancreas of the LA/N-corpulent rat.

Islets of Langerhans in sections from the tail of the pancreas of corpulent LA/N-cp rats and lean controls aged 1, 3, 6 and 9 mo were examined by immunocytochemistry and morphometrically using an automatic image analyzer. The corpulent rats had significantly greater islet volumes at all ages, although islet hypertrophy tended to plateau after 6 mo. By 12 mo age the architecture of the islets was disrupted with large islets fused and showing areas of fibrosis and deposits of hemosiderin. The volume density (v/v, %) of islets in the parenchyma was significantly increased at each age step in corpulent rats reaching over 20% at 9 mo, and was greater in corpulent than in lean rats at all ages. In the corpulent rats, B-cell volume density dramatically with age and at all ages was significantly greater in corpulent than in lean rats. A-cell volume density was significantly greater in the corpulent rats than in lean rats at 1 and 9 mo. The mean B:A cell ratio was greater in corpulent than in lean rats at 3, 6 and 9 mo. There were more D cells per islet in corpulent than in lean rats up to 9 mo. These changes in cell populations were paralleled by qualitative changes in islet morphology and cellular topography such as increasingly irregular islet shape in corpulent animals and by variations in plasma levels of insulin and glucagon. In this strain of rats, obesity is associated with major changes in pancreatic morphology and this correlates strongly with the susceptibility of the strain to atherosclerosis.

Aging↗
PubMed1986

Early atherosclerotic lesions in a susceptible rat model. The LA/N-corpulent rat.

The LA/N-cp rat, when homozygous for the mutant cp gene, is obese and moderately hyperlipidemic. Body weight of homozygotes reaches approximately 950 g compared to 400 g for lean heterozygotes. In adult animals plasma triglycerides are 330 mg/100 ml compared to 40 mg/100 ml, and total cholesterol is 215 mg/100 ml, compared to 80 mg/100 ml in heterozygotes. We have examined the arteries of pressure perfusion fixed animals of 9 months age by scanning electron microscopy. Our technique shows normal endothelium in clear detail with each individual cell and its surface structure well defined. Numerous lesions were found in the arteries, including dead endothelial cells, polygonal cells, varying areas of desquamation with attached blood elements, frank ulcerated lesions and old rechannelized thrombus. The lesions were present in both homozygous cp and heterozygous animals, but were more frequent and severe in homozygous rats. We suggest that this strain of rats may provide a useful, inexpensive model for studies on atherosclerosis.

Animals↗
PubMed1986

Plasma lipids and other factors in the LA/N corpulent rat in the presence of chronic exercise and food restriction.

The effects of regular exercise and food restriction were studied in the LA/N corpulent rat up to age 9 months. This congenic strain of the Lister and Albany rat is normotensive, corpulent, and hyperlipidemic when homozygous for the corpulent (cp) gene derived from the Koletsky strain. Food restriction of corpulent animals to the intake of matched lean rats caused body weight to be significantly lower, although not as low as that of the lean animals. Plasma total cholesterol in freely eating sedentary corpulent animals was significantly higher (210 mg/100 mL) than in food-restricted rats (165 mg/100 mL), in which plasma cholesterol was considerably elevated compared with lean rats (80 mg/100 mL). Exercise caused a modest but significant increase in both total and high density lipoprotein cholesterol in both corpulent and lean rats. The rise was greater in corpulent rats and, in food-restricted exercising corpulent rats, the cholesterol concentrations were equivalent to those of freely eating corpulent animals. Systolic blood pressure in lean rats fell slowly from 146 mmHg at 8 weeks to 132 mmHg at 36 weeks and was not affected by exercise. Sedentary corpulent rats showed a rapid rise in systolic pressure from 107 mmHg at 7 weeks to 128 mmHg at 11 weeks. This rise was reduced by food restriction and completely prevented by the combination of food restriction and exercise. Thus, in this strain of rats exercise was associated with higher plasma cholesterol concentrations, while food restriction had limited effects.

Animals↗
PubMed1986

Myocardial and vascular lesions in the LA/N-corpulent rat.

The LA/N-corpulent (LA/N-cp) rat is a normotensive strain derived from Koltesky's original mutant strain of the spontaneously hypertensive rat (SHR). When homozygous for the cp gene (cp/cp), the rats are hyperphagous, hyperlipidemic, hyperinsulinemic, and obese. The rats have been shown, by scanning electron microscope observation of the arterial system, to develop arterial lesions and occasional occlusive thrombi. These are significantly more frequent in the corpulent rats. Histological examination of the heart has shown the presence of four distinguishable types of lesions: type A, muscle scar or cell dropout with pigment deposition and inflammatory cell accumulation; type B, necrosis of a small number of myocytes with reactive inflammatory cells; type C, nodule of chronic inflammatory cells; type D, muscle scar without chronic inflammatory cells. Complete transverse sections of three regions of the heart were examined from rats 3, 6, and 9 months of age. Rats that were homozygous normal (+/+) showed an absence of all types of cardiac lesions. Male corpulent rats showed frequent lesions of all types with the frequency rising consistently with age. Female corpulent rats showed a similar incidence of types C and D lesions to males, but no type B lesions were found. Type A lesions, the most common in corpulent males, were found at a greatly reduced relative frequency. In some instances, we have found occlusive thrombi in a coronary artery of corpulent rats. The disease process in these animals occurs with a normal low fat, virtually cholesterol-free diet and no experimental manipulation.

Animals↗
PubMed1986

Dynamic torquemeter calibration of bicycle ergometers.

Bicycle ergometers as widely used in both clinical testing and exercise physiology studies are mechanical, hydraulic, or electromechanical devices. They are thus subject to change and error, creating a need for repeated calibration. We have developed a compact inexpensive torquemeter that permits dynamic calibration of the entire range of an ergometer. The torquemeter continuously measures the input torque at the pedal shaft of the ergometer and thus includes all work done in the drivetrain. It also permits adjustment of electrically braked ergometers to a specified torque using internal adjustments to give correct scale readings. The torquemeter depends on a high carbon steel torsion spring whose ends are rotated in angular deflection by increasing applied torque. Relative rotation is sensed through a multiturn potentiometer, the resistance of which is measured externally through a slip ring contact.

Biomedical Engineering↗
PubMed1985

A comparative examination of the in vitro metabolism of five cyclopenta[a]phenanthrenes of varying carcinogenic potential.

Metabolites of 15,16-dihydrocyclopenta[a]phenanthren-17-one and its 1- and 12-methyl homologues (all non-carcinogens) along with those from the 11-methyl and 11,12-dimethyl-17-ketones (carcinogens), produced in vitro by hepatic microsomes from methylcholanthrene induced rats, were separated by reverse phase h.p.l.c. Identifications of individual metabolites were based upon elution times, u.v. spectra, and in some cases by mass spectrometry, circular dichroism, and identity with synthetic derivatives. All five compounds were biologically oxidised at their terminal A and D rings to yield 1,2-dihydrodiols and 15- and 16- ols; with the exception of the 1-methyl compound, all also gave similar amounts of 3,4-dihydrodiols. The 1-methyl compound by contrast failed to produce this metabolite, furnishing instead the 4-phenol and five other, probably related phenolic derivatives. Previous work has established that for the 11-methyl-17-ketone, the 3,4-dihydrodiol is the proximate carcinogen. Thus, whereas lack of biological activity with the 1-methyl compound can be ascribed to its failure to produce a 3,4-dihydrodiol, in the case of the unsubstituted parent ketone and its 12-methyl derivative other determining factors must come into play.

Animals↗
PubMed1985

Comparison of the binding of some carcinogenic and non-carcinogenic cyclopenta[a]phenanthrenes to DNA in vitro and in vivo.

After microsomal activation in vitro, both the strong carcinogen 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one and its inactive 12-methyl isomer bind covalently to added DNA, in the ratio approximately 6:1 (1595 and 254 mu mol/mol of DNA phosphorus, respectively). Over a thousand times less binding was observed when DNA was isolated from the skin of groups of mice that had received a topical dose of 1000 nmol of these two compounds, and of the unsubstituted ketone (non-carcinogen) and its 11,12-dimethyl derivative (carcinogen), 48 h previously; the binding ratios were 458, 155, 19 and 974 nmol/mol DNA phosphorus, respectively. Covalent binding of the 11-methyl compound to mouse skin DNA, measured 48 h after topical application, was linear with dose over the range 50 - 1000 nmol. It has previously been demonstrated for groups of mice initiated with 200 or 400 nmol of this carcinogen and promoted by repeated application of croton oil that skin tumour incidences were 50 and 70%, respectively. For a topical dose of 1000 nmol of the inactive 12-methyl isomer DNA binding in skin falls in this range, equivalent to DNA binding given by approximately 340 nmol of the carcinogen. Thus although the inactive unsubstituted parent compound essentially fails to bind to skin DNA after topical application, there does not seem to be a consistent relationship between extent of DNA binding in vivo and carcinogenicity among these cyclopenta[a]phenanthrenes. However, loss of the 12-methyl adducts from skin followed a logarithmic course over the first 10 days following application, with a half life of 3.5 days. In contrast, it was previously shown that removal of the 11-methyl adducts could not be measured above the normal rate of DNA turnover for this mouse tissue (half life, 6-7 days). It is suggested that active DNA repair of the 12-methyl lesions may contribute to the lack of activity of this isomer.

Animals↗