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Biomedical subjects

J B Simpson

Publications and source records attributed to J B Simpson.

At least 55 records · Page 3Linked to original sources
PubMed1987

Water drinking caused by intracerebroventricular infusions of hypertonic solutions in cattle.

Infusions into the lateral cerebral ventricle of hypertonic solutions of NaCl, mannitol or sucrose all induced water drinking in cattle. However, infusion of hypertonic NaCl caused a significantly greater water drinking response than did the infusions of mannitol or sucrose, despite the fact that CSF osmolality increase was similar. In contrast, hypertonic solutions of NaCl or mannitol had similar dipsogenic effects when infused intravenously. The intracerebroventricular infusions of hypertonic NaCl or mannitol did not affect the intakes of food or Na solution. The results are consistent with the hypothesis that both cerebral osmoreceptors and Na sensors are involved in regulating thirst in cows.

Animals↗
PubMed1987

Sodium appetite and cerebrospinal fluid sodium concentration during hypovolemia.

A lowered concentration of sodium in the cerebrospinal fluid (CSF) has been suggested as a critical signal for the elicitation of sodium appetite. This was evaluated in naive male Long-Evans rats made hypovolemic by subcutaneous injection of the colloid polyethylene glycol (PEG) in a hyperoncotic concentration. At 2, 5 or 8 h after PEG or vehicle injection, under conditions of availability or non-availability of water and 0.3 M NaCl for ingestion, the rats were anesthetized and samples of CSF and blood were taken. Water intakes of the PEG treated rats were elevated at 5 and 8 h, and 0.3 M NaCl intakes were elevated at 8 h in comparison to vehicle treated rats. When fluids were not available, CSF sodium concentrations were greater in PEG than in vehicle treated rats at 2, 5 and 8 h. When fluids were available, CSF sodium concentrations were greater in PEG than in vehicle treated rats at 5 and at 8 h. There was no correlation between CSF sodium concentration and saline intake. In summary, a lowered CSF sodium concentration is not a necessary condition for sodium appetite in the hypovolemic rat.

Animals↗
PubMed1987

Separation of captopril effects on salt and water intake by subfornical organ lesions.

Several experiments tested whether the subfornical organ (SFO) is necessary for water or NaCl intake arising from angiotensin-converting enzyme (CE) blockade with captopril (CAP) in the drinking fluids (0.1 mg/ml). Peripheral CAP was given to rats acutely following 24-h water deprivation or chronically over several days, either with water alone available for drinking or with 0.3 M NaCl in choice with water. Control rats drank more water, and NaCl when it was available, during CAP treatment, whereas rats with SFO damage increased NaCl intake only. CAP decreased urinary volume (UV) and increased urinary potassium excretion (UKV) during rehydration with only water available and increased urinary sodium excretion (UNaV) with NaCl present. Regardless of CAP treatment, rats with SFO damage had increased electrolyte concentrations and excretions during rehydration with only water available and increased UK with NaCl present, compared with controls. Oral CAP did not have an aversive taste at the dose used here. We conclude that the SFO is necessary for CAP-enhanced water, but not NaCl, intake and suggest that different neurological mechanisms control ingestion of each fluid during CAP.

Animals↗
PubMed1987

Attenuated sodium appetite in response to sodium deficiency in Fischer-344 rats.

Fischer-344 (F-344) rats avoid NaCl solutions which are preferred by other strains. The present studies examined Na appetite induced by two methods: maintenance on a Na-deficient diet, and Na depletion by injection of furosemide. In comparison with outbred Wistar rats, F-344 rats showed no evidence of Na appetite induced by Na-deficient diet after the first 15 min (study 1) and demonstrated attenuated Na appetite in response to the natriuretic effects of furosemide (study 2). Since Na loss by Wistar and F-344 rats was similar, it is likely that this reduced Na appetite was due to hedonic differences between the strains rather than to differential renal response to furosemide or Na-deficient diet.

Animals↗
PubMed1986

Angioplasty at coronary bifurcations: single-guide, two-wire technique.

A technique is described for angioplasty at coronary bifurcations. This simple approach utilizes a single guiding catheter, an exchange wire, and a conventional dilatation catheter and guidewire. With this "protective" guidewire technique, side branches at risk from occlusion during dilatation of a primary coronary segment can be protected and dilated secondarily; continual access to the threatened side branch is maintained with a "standby" exchange wire in the branch vessel.

Angioplasty, Balloon↗
PubMed1986

Drinking and natriuresis during volume expansion and intracranial angiotensin or carbachol.

Two methods of sodium loading were used to counteract the body fluid dilution resulting from natriuresis and water drinking during sustained lateral ventricular infusions of carbachol (CBC) or angiotensin II (ANG II) in rats. It was expected that preventing dilution would also prevent the precipitous decline of both drinking and natriuresis during the later hours of CBC infusion. In the first study, rats having isotonic saline as the sole drinking fluid during CBC infusions drank less fluid and had only slightly higher plasma osmolality and sodium concentration than rats drinking water, which showed extreme dilution. In the second study, rats with only water to drink were given intravenous infusions of 0.15, 0.45, or 1.00 M NaCl solutions at 1.8 ml/h concurrently with the intraventricular infusions. Significant dilution of plasma was found at the two lower rates but not at 1.00 M NaCl in CBC-infused rats. Only the latter group showed both persistent drinking and natriuresis throughout the 4-h infusion period, and this was not because of elevated plasma osmolality. Infusions of ANG II generated less severe body fluid dilution and more persistent drinking in both experiments. The study demonstrates that body fluid dilution may control the offset of both drinking and natriuresis during sustained infusions of CBC and that the more persistent drinking to ANG II vs. CBC probably occurs because of a lesser natriuresis and consequent fluid dilution.

Administration, Oral↗
PubMed1986

Improved fluorescence polarization assay for use in evaluating fetal lung maturity. I. Development of the assay procedure.

We describe a fluorescence polarization assay for use in predicting fetal lung maturity, which is suitable for the TDx Analyzer (an automated fluorescence polarimeter). The assay requires 0.5 mL of amniotic fluid and approximately 30 min, and involves the fluorophore 1-palmitoyl-2(6-[(7-nitro-2, 1, 3-benzoxadiazol-4-yl)amino]caproyl) phosphatidylcholine. Reproducible polarization measurements depend on proper regulation of incubation time and temperature, but variations in the concentrations of fluorescent probe and amniotic fluid have little effect on measured polarization and therefore little effect on assay precision. Working solutions of the fluorescent probe are stable for at least nine months when stored at -20 degrees C and pH 5. Interferences include erythrocytes, serum, bilirubin, meconium, and lidocaine.

Amniotic Fluid↗
PubMed1985

Diuresis and reduction of salt appetite by lateral ventricular infusions of atriopeptin II.

Infusions of 60 pmol/h atriopeptin II into the lateral ventricles stimulated urine flow in both normally hydrated and sodium depleted conscious rats without any increase in the excretion of sodium, potassium or total solutes. The urinary sodium concentration and osmolality both declined significantly. In addition to the renal effects, cerebroventricular infusions of 60 pmol/h atropeptin II reduced salt appetite in rats following depletion of sodium by combined treatment with furosemide diuresis and low sodium diet. Neither 60 nor 600 pmol/h doses had any effect on urine volume or concentration during intravenous infusions, so the effects appear to be mediated by the central nervous system (CNS). Atriopeptins may act through the CNS to facilitate reduction of extracellular volume in synergy with peripheral natriuresis: by increasing urine flow independently from natriuresis; and by restricting further expansion of extracellular volume by reducing salt appetite.

Animals↗
PubMed1985

Modulation of salt appetite by lateral ventricular infusions of angiotensin II and carbachol during sodium depletion.

Infusions of angiotensin II (AII) or carbachol (CBC) into the lateral ventricles of rats which had been depleted of sodium 4 h previously with either furosemide or polyethylene glycol produced significant changes in salt appetite and sodium and water balances relative to rats infused with saline vehicle. Infusions of AII enhanced the salt appetite and led to rapid retention of both sodium and water. Infusions of CBC abolished the salt appetite and consequently did not produce any increase in sodium balance. Water intake was greater in both AII- and CBC-infused than in vehicle-infused rats and water balances increased during CBC infusion, causing severe dilution of plasma osmolality, sodium and potassium concentrations. Carbachol thus suppressed salt appetite, despite a considerable worsening of the condition of body sodium in these hypovolemic animals. Angiotensin II facilitated the appetite and this enhancement was not secondary to any natriuresis produced by AII infusions.

Angiotensin II↗
PubMed1985

Fluid intake, distribution, and excretion during lateral ventricular infusions of carbachol in rats.

Infusion of carbachol into the lateral ventricles of rats at rates of 400 or 2000 ng/h for 6 h produced dose-related natriuresis, kaliuresis, and water drinking but no consumption of hypertonic NaCl solution. Electrolyte excretion and water intake were maximal during the first 2 h, and no further increases occurred after 4 h. Sodium losses were estimated as 15-30% of total extracellular sodium. Continuous infusion of 2000 ng/h carbachol for 6 days produced a chronic increase of water intake but no increased consumption of saline. Sodium balances were negative during the first day of infusion, but gradually returned to normal over 6 days. Plasma volume, hematocrit, and plasma sodium and potassium concentrations were normal in carbachol-infused animals on the 6th day. Cholinergic stimulation of the brain thus appeared to interfere with the usual salt appetite following sodium loss.

Animals↗
PubMed1985

Angioplasty in total coronary artery occlusion: experience in 76 consecutive patients.

The influence of multiple clinical, angiographic and technical variables on the outcome of percutaneous transluminal coronary angioplasty was evaluated in a group of 76 consecutive patients with total coronary artery occlusion. Angioplasty was performed successfully in 53% of these patients. The likelihood of successful angioplasty was favorably influenced by: 1) a history of prior myocardial infarction in the distribution of the occluded arterial segment (p = 0.03); 2) an estimated maximal duration of arterial occlusion of less than 20 weeks (p less than 0.001); and 3) a length of nonvisualized arterial segment distal to the point of occlusion of less than 1.5 cm (p = 0.03). The outcome of coronary angioplasty was not significantly influenced by the vessel involved, the location of the occlusion within an involved vessel, the morphology of the occlusion (tapered versus abrupt) or the age and sex of the patient. There were no deaths and no vascular perforations. Four patients had recurrent coronary occlusion within 24 hours of the procedure; in three of these, recurrent occlusion was successfully treated with reangioplasty and in one, emergent surgical revascularization was performed. Embolic occlusion of an arterial branch distal to the point of total coronary occlusion occurred in 4 of the 40 successfully recanalized arteries. Seventy-five percent of patients having successful recanalization of an occluded coronary artery were free of the anginal symptoms that had prompted performance of the procedure at a mean follow-up period of 7.3 months. Thus, angioplasty of a total coronary artery occlusion can be performed safely and effectively, particularly in patients with a history of prior myocardial infarction, a brief estimated duration of coronary occlusion and a short nonvisualized occluded arterial segment.

Adult↗
PubMed1985

Absence of sodium chloride preference in Fischer-344 rats.

Preference for NaCl solutions as a function of concentration was examined in three inbred strains of rats (Munich-Wistar, Buffalo, and Fischer-344) and outbred Wistar rats. Fischer-344 rats were found to differ markedly from the other strains in that they failed to prefer any concentration of NaCl solution to water. This difference did not appear to be due to an insensitivity to the taste of NaCl since they significantly avoided solutions at concentrations (greater than 0.7%) that were strongly preferred by other rat strains. Differences between Fischer-344 and other rat strains also did not appear to be due to a generally anomalous taste system since their intake and preference for prototypes of other basic tastes (sweet, sour, and bitter) were generally similar to those of other strains. Although Fischer-344 rats were somewhat slower than Wistar to excrete a sodium load, it is unlikely that this difference can provide a direct explanation of the aversion of Fischer-344 rats for NaCl.

Animals↗
PubMed1985

Protective effects of trifluralin on benzo(a)pyrene-induced tumors in A/J mice.

Trifluralin, a widely used herbicide, added to the diet before the p.o. administration of benzo(a)pyrene (BP) and fed continuously, significantly inhibited the induction of lung and forestomach tumors in female A/J mice. Dietary intake of trifluralin before the administration of BP resulted in a significant increase in glutathione in lung and forestomach but not in liver and glandular stomach. Trifluralin treatment also inhibited the binding of [3H]BP to liver and lung DNA, as well as to protein in the liver. Under these conditions, the protection against BP-induced lung tumors and perhaps forestomach tumors may be due to an elevation of tissue glutathione, resulting in a decreased binding of reactive metabolites of BP to macromolecules at these sites. The results indicate that trifluralin has a "blocking" effect in its inhibition of BP-induced tumors. Our studies show that trifluralin also inhibits chemical carcinogenesis in lung and forestomach when started in the diet 1 day after the administration of BP and fed continuously thereafter. In the case of lung, although maximum inhibition of tumors occurred when trifluralin was started 1 day after BP, there was significant protection at all time intervals (0 to 7 days) against lung tumors. The finding that trifluralin protects against BP tumorigenesis when started in the diet after the administration of the carcinogen clearly demonstrates that trifluralin also has a "suppressive" effect against BP-induced tumors.

Animals↗