Biomedical subjects

C V Jackson

Publications and source records attributed to C V Jackson.

27 records · Page 2Linked to original sources

PubMed1985

Effects of bepridil on regional and global myocardial ischemia/reperfusion-induced injury.

The effectiveness of the calcium entry blocker bepridil in protecting the myocardium from ischemic injury, was assessed in a canine model of regional ischemia and in a feline model of global ischemia. Bepridil administration (5 mg/kg or 15 mg/kg/24 h intravenously) did not reduce ultimate infarct size as assessed in anesthetized, open-chest dogs subjected to 90 min of occlusion of the left circumflex coronary artery and 24 h of reperfusion. Bepridil (5 mg/kg administered intravenously to a blood donor cat) did not provide any protection of the isolated blood-perfused cat heart from 90 min of normothermic global ischemia and 60 min of reperfusion. Treatment of the perfused cat heart with bepridil did not prevent tissue accumulation of calcium or loss of tissue potassium and ATP. Bepridil, however, significantly reduced reperfusion tachyarrhythmias in the dog model for assessing ultimate infarct size and prevented reperfusion-induced ventricular fibrillation of the cat isolated heart. These results indicate that the calcium entry blocker, bepridil, as assessed in the models employed, does not protect the myocardium from ischemic reperfusion injury. However, it does prevent reperfusion-induced tachyarrhythmias and ventricular fibrillation.

Adenosine Triphosphate↗

PubMed1985

Role of fiberoptic bronchoscopy in patients with hemoptysis and a normal chest roentgenogram.

We reviewed the charts of 48 consecutive patients who had fiberoptic bronchoscopy performed in the evaluation of hemoptysis with a normal chest roentgenogram. Fiberoptic bronchoscopy provided a diagnosis other than endobronchial inflammation in only four patients--benign fibromuscular polyp in one patient, Mycobacterium tuberculosis in 1 patient, and carcinoma in two others. A literature review revealed an overall 3 percent incidence of bronchogenic carcinoma in patients with hemoptysis and normal findings on chest roentgenogram. Other than abnormal findings on chest roentgenogram, risk factors for carcinoma in patients with hemoptysis include: (1) age greater than 40; (2) significant smoking history; and (3) duration of hemoptysis for longer than one week. We concluded that in patients with hemoptysis and normal chest x-ray film findings, routine fiberoptic bronchoscopy may not always be indicated to rule out malignancy.

Adult↗

PubMed1985

A functional and ultrastructural analysis of experimental diabetic rat myocardium. Manifestation of a cardiomyopathy.

The effects of experimental diabetes on cardiac function and ultrastructure were studied in rats that had been diabetic for 6-24 wk. Experimental diabetes was produced by the intravenous (i.v.) injection of 65 mg/kg streptozocin (STZ) into rats 42-43 days old. Diabetic rat hearts perfused at 15 cm H2O on the working heart apparatus demonstrated depressed cardiac function (i.e., lower left ventricular pressure and +/- dP/dt) at 6, 12, and 24 wk of diabetes. Electron microscopic analysis of ventricular myocardium revealed increased lipid deposition from 6 to 24 wk of diabetes and progressive deterioration of the myocardial cell integrity at 12 and 24 wk of diabetes. This deterioration was characterized by loss of contractile protein, vacuolization (swollen sarcoplasmic reticulum), myelin formations, myocytolysis, and contracture bands. These alterations paralleled the depression of cardiac function at 12 and 24 wk of diabetes. There was, however, depressed function at 6 wk of diabetes but no observable alterations in myocardial ultrastructure. Therefore, experimental diabetes produced ultrastructural alterations in the rat heart that manifested themselves only after a demonstrable depression in cardiac function.

Animals↗

PubMed1981

Supersensitivity of isolated mesenteric arteries to noradrenaline in the long-term experimental diabetic rat.

1 In the present investigation, noradrenaline-induced vascular contractions in isolated rat mesenteric arteries were studied in short and long-term experimental diabetic rats. The diabetic state was induced with streptozotocin (65 mg/kg, i.v.). 2 Long-term diabetic rats were hypertensive when compared to age-matched control rats. In contrast, short-term diabetic rats appeared to be hypotensive when compared to age-matched control rats. 3 Long-term diabetic mesenteric arteries were supersensitive to noradrenaline and developed more contractile force in response to noradrenaline when compared to age-matched control mesenteric arteries. beta-adrenoreceptor antagonism had no effect on the sensitivity of the mesenteric arteries (diabetic and control) for noradrenaline, however, there was an increase in the contractile force developed by these tissues in response to noradrenaline during beta-adrenoreceptor antagonism. 4 alpha-Adrenoreceptor antagonism produced a decrease in the sensitivity of both long-term diabetic and corresponding age-matched control mesenteric arteries. alpha-Adrenoreceptor antagonism had no effect on contractile force developed by long-term mesenteric arteries (diabetic and control) in response to noradrenaline. 5 The present data indicate that long-term experimental diabetes produces a supersensitivity of rat mesenteric arteries to noradrenaline. This phenomenon is dependent upon the duration of the diabetic state. Supersensitivity of the mesenteric arteries to noradrenaline may indicate an increased arterial vascular resistance which may contribute to the observed hypertension.

Adrenergic alpha-Antagonists↗

PubMed1980

Countercurrent immunoelectrophoresis in the evaluation of infants with group B streptococcal disease.

Admission specimens of CSF, serum, and urine from 67 patients with proved group B streptococcal (GBS) bacteremia and/or meningitis were evaluated by countercurrent immunoelectrophoresis (CIE). Group B and type-specific antigens were detected in 81% of CSF, 63% of serum, and 96% of concentrated urine specimens by CIE. Each of 26 infants with meningitis from whom all three body fluids were available and ten with bacteremia from whom both serum and urine were collected at admission had GBS antigens detected by CIE in at least one specimen. No false positive reactions were observed. Among patients with type III, GBS meningeal infection, fatal outcome or neurologic sequelae were significantly correlated with concentration of type III antigen in admission CSF and duration of antigenuria when compared to normal survivors (P = less than .05, Mann-Whitney U tests). CIE appears to be a useful diagnostic and prognostic tool for infants with GBS infection if admission specimens from more than one source are examined and appropriately high-titered antisera are employed for testing.

Antigens, Bacterial↗

PubMed1979

Influence of dimethyl sulfoxide (Me2SO) on vascular smooth muscle.

The present investigation was undertaken to determine the action of dimethyl sulfoxide (Me2SO) on vascular smooth muscle. The rabbit isolated aortic strip preparation was used. In the present study, Me2SO-induced relaxation of isolated rabbit aorta was demonstrated. The degree of relaxation induced by Me2SO was concentration dependent. In the presence of Me2SO the action of norepinephrine, histamine, carbachol and potassium was significantly (P less than .05) antagonized. The control ED50 values were 5.36 + 0.50 + 10(-8) M, 3.38 +/- 0.74 X 10(-6) M, 1.40 +/- 0.82 X 10(-6) M and 2.43 +/- 0.19 x 10(-2) M, respectively. In the presence of Me2SO the ED50 values were 2.23 +/- 0.23 x 10(-6) M, 1.80 +/- 0.40 X 10(-5) M, 1.00 +/- 0.38 X 10(-4) and 4.21 +/- 0.07 x 10(-2) M, respectively. The maximum response of the tissue to the various vasoactive agents was significantly depressed in the presence of Me2SO. When Me2SO was present in the efflux medium, the amount of 45Ca2+ washed out of aortic strips was significantly (P less than .05) reduced when compared to control. The 45Ca2+ efflux studies supported the hypothesis that Me2SO-induced relaxation could possibly result from enhanced binding of activator Ca2+ to high affinity Ca2+ sites.

Animals↗

PubMed1979

Influence of age on norepinephrine-induced vascular contractions as a function of extracellular calcium.

Age has been shown to produce various morphological and biochemical changes within the vasculature as well as changes in the responsiveness of the vasculature to various drugs. In the present study, the influences of age and extracellular calcium on norephinephrine-induced aortic contractions in male rats were examined. The aging process resulted in a decrease in sensitivity and responsiveness of rat aorta to norepinephrine-induced contractions. The progressive decrease in maximum contractile force (mg force/mg tissue) in response to norepinephrine as the result of aging occurred in all the different extracellular calcium concentrations used. In addition, the EC50 for norepinephrine in aortae from younger animals was directly related to the extracellular calcium concentration. As the animals, however, became progressively older (49-63 weeks) the aortic tissues became less sensitive and the calculated EC50 for norepinephrine was not altered by changes in the extracellular calcium concentration.

Aging↗

PubMedDate not supplied

Influence of short-term experimental diabetes on blood pressure and heart rate in response to norepinephrine and angiotensin II in the conscious rat.

Hypertension, atherosclerosis, arteriosclerosis, and cardiomyopathy account for 80% of all diabetic deaths. A paucity of data exists concerning reactivity of the diabetic vasculature to vasopressor substances. The purpose of this investigation was to determine the influence of short-term (4-5 weeks) diabetes on the responsiveness of the cardiovascular system to vasopressor substances in the intact conscious rat. Diabetes was chemically induced with streptozotocin (65 mg/kg i.v.) in 42-43-days-old, nonfasted, male Sprague-Dawley--derived rats. Direct blood pressure and heart rate were recorded, and responses to the vasopressor agonists norepinephrine and angiotensin II were obtained. Short-term diabetic rats were hypotensive and had lower heart rates when compared with control rats. Blood pressure responses to norepinephrine and angiotensin II were depressed in the short-term diabetic rat; however, the baroreceptor reflexes in these rats were more sensitive to increases in blood pressure. Therefore, it appears that there is some type of nonspecific alteration in the responsiveness of the cardiovascular system to the vasopressor agonists in the short-term diabetic rat.

Alloxan↗

PubMedDate not supplied

Increased risk of group B streptococcal disease in twins.

Infants who are the product of multiple births comprise a newly defined group of patients at increased risk for the development of invasive, group B streptococcal infection. This report summarizes the clinical and bacteriological features of 11 sets of twins and one set of triplets in which one (nine sets) or more (three sets) infants had proved early- or late-onset group B streptococcal infection. Reasons for the enhanced susceptability of index patients and their siblings are discussed. On the basis of these observations, an emperical approach is proposed for the treatment of the apparently noninvolved sibling of a twin with invasive group B streptococcal infection.

Antibodies, Bacterial↗