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Biomedical subjects

N Jackson

Publications and source records attributed to N Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1986

Haemodynamic dose-response effects of intravenous indoramin in acute heart failure complicating myocardial infarction.

The haemodynamic dose-response effects of intravenous indoramin were evaluated in 12 patients with acute heart failure (pulmonary artery occluded pressure of greater than 20 mm Hg) complicating a recent myocardial infarction. Following a 1-h control period with confirmed stable haemodynamics, the effects of three intravenous bolus doses of indoramin (0.125, 0.125, and 0.25 mg/kg at 15-min intervals) were determined in the 10- to 15-min period following each intravenous injection. Plasma drug concentrations rose with the administered dose and were in the previously established therapeutic range. Ten patients tolerated all three doses of the drug; two patients were withdrawn following the second dose owing to clinically evident hypotension (systolic blood pressure of less than 100 mm Hg). Indoramin resulted in progressive falls in systolic, diastolic, and mean systemic arterial pressures (p less than 0.01) without change in cardiac index. There was a dose-related reduction in the heart rate (0.5 mg/kg; -7 beats/min; p less than 0.01). The left ventricular filling pressure showed a significant and quadratic reduction over the dose range (0.5 mg/kg, -5 mm Hg; p less than 0.01). The systemic vascular resistance index was reduced (-333 dynes X s X cm-5 X m2; p less than 0.001) and the stroke volume index increased (+3 ml/m2; p less than 0.05) following the maximum cumulative dosage. These data established the therapeutic safety of indoramin (0.125-0.5 mg/kg) in acute heart failure following myocardial infarction. An improvement in cardiac performance in these patients was compatible with circulatory actions on both cardiac preload and afterload.

Acute Disease↗
PubMed1986

Therapeutic touch.

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Holistic Health↗
PubMed1985

Hemodynamic dose-response effects of flecainide in acute myocardial infarction with and without left ventricular decompensation.

We evaluated the hemodynamic effects of the class I antiarrhythmic flecainide in 20 patients within 18 hours of an acute myocardial infarction. Equal numbers of patients with normal (group 1) or decompensated (group 2) ventricular function were studied. Both groups received flecainide, 1 mg/kg, as an intravenous bolus over 10 minutes, followed by infusion (1.6 mg/kg/hr) over the next 120 minutes. Plasma concentrations increased linearly with the cumulative flecainide dosage in both groups. There was no difference between the groups in the plasma levels reached, which were within the recognized antiarrhythmic range for flecainide (200 to 1000 ng/ml) throughout the infusion. The hemodynamic effects of flecainide for each group were decreases in systolic blood pressure (maximum 3% fall in group 1 and 8% fall in group 2), cardiac index (9% fall in group 1 and 18% fall in group 2), stroke volume index (13% fall in group 1 and 23% fall in group 2), stroke work index (14% fall in group 1 and 27% fall in group 2), with an increased heart rate (8% rise in group 1 and 5% rise in group 2), pulmonary artery occluded pressure (27% rise in group 1 and 21% rise in group 2), and systemic vascular resistance (11% rise in group 1 and 18% rise in group 2). Diastolic and mean arterial blood pressures did not change. Our data demonstrate that flecainide induced significant cardiodepression in both groups of patients. These effects were not significantly greater in patients with adequately controlled heart failure. These data suggest that the mild negative inotropic properties of flecainide in patients with recent myocardial infarction are comparable to those described for other class I antiarrhythmics.

Adult↗
PubMed1985

Haemodynamic analysis of the effects of nicardipine and metoprolol alone and in combination in coronary artery disease.

The circulatory consequences of concurrent slow-calcium channel (nicardipine) and cardioselective beta blockade (metoprolol) were evaluated in 20 patients with angiographically proven coronary artery disease. The rest and exercise haemodynamic impact of intravenous nicardipine (10 mg) or metoprolol (10 mg) alone was determined by randomly allocating 10 patients to each drug; finally all patients were assessed on combination therapy. The plasma levels of nicardipine (17 +/- 3 to 53 +/- 6 ng ml-1) and metoprolol (36 +/- 5 to 97 +/- 16 ng ml-1) achieved at the time of each study were in the established therapeutic range. At rest nicardipine reduced systemic mean arterial pressure and systemic vascular resistance index; cardiac and stroke volume indices increased without change in pulmonary artery occluded pressure. Metoprolol alone reduced systemic blood pressure, heart rate and cardiac index, and increased systemic vascular resistance index. Combination therapy reduced systemic arterial blood pressure and heart rate with relatively modest effects on cardiac index, systemic vascular resistance index and pulmonary artery occluded pressure. During dynamic exercise nicardipine reduced systemic mean and diastolic arterial pressure and stroke work index without change in other haemodynamic variables. Metoprolol reduced exercise systemic arterial pressures, heart rate and cardiac index, and increased systemic vascular resistance index and pulmonary artery occluded pressure. Combination therapy produced changes similar to those at rest; at peak nicardipine pharmacodynamic activity, the cardiac depressant actions of metoprolol were largely offset by the induced reduction in left ventricular afterload.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Anti-hypertensive dose-response effects of nicardipine in stable essential hypertension.

The dose-response effects of oral nicardipine on the systemic blood pressure were examined in 54 patients with uncomplicated essential hypertension (DBP greater than or equal to 100 mm Hg). The study was designed in four sequential stages. A 2 week single-blind placebo run-in period was followed by dose titration with nicardipine at 2 week intervals. Patients achieving the target DBP less than or equal to 95 mm Hg were then crossed over to placebo for 2 weeks, following which the previous dose of nicardipine was readministered for 6 weeks. Forty-eight patients completed the dose-titration phase. The target DBP 95 mm Hg was achieved in 33; in eight after 10 mg three times daily, in 21 after 20 mg three times daily, in three after 30 mg three times daily and in one after 40 mg three times daily. In the 48 patients, systolic blood pressure was reduced from 188 +/- 25 to 158 +/- 21 mm Hg (P less than 0.001) and diastolic blood pressure from 111 +/- 9 to 93 +/- 13 mm Hg (P less than 0.001); heart rate increased from 81 +/- 7 to 87 +/- 13 beats min-1 (P less than 0.01). Thirty-one of the 33 patients completed the crossover to placebo, which was accompanied by a significant increase towards pretreatment blood pressure levels. Reinstitution of nicardipine at the previous dose resulted in a reduction of SBP and DBP to levels not significantly different from those at the end of the dose-titration stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

A study of the long-term efficacy and tolerability of oral nicardipine in hypertensive patients.

This study was designed to evaluate the efficacy of oral nicardipine in 91 patients with uncomplicated essential hypertension over a period of 12 months. All patients started on a fixed nicardipine dose of 30 mg three times daily which was adjusted in the range 10-40 mg three times daily, where necessary to achieve a target diastolic blood pressure less than 95 mm Hg. At 6 weeks, blood pressure (mean +/- s.e. mean) was reduced from an average of 190 +/- 22/112 +/- 8 to 167 +/- 23/96 +/- 11 mm Hg supine and from 180 +/- 21/113 +/- 7 to 154 +/- 17/95 +/- 11 mm Hg standing and remained controlled in all patients throughout the study. A total of 96 unwanted experiences were reported by 49 patients (54%); 17 (19%) reported a single symptom once and two (2%) reported a single symptom more than once. The most frequently reported adverse experiences were peripheral oedema in 27 (28%) and headaches in 15 patients (16%). The majority of the adverse experiences occurred in the first 3 months of treatment. Ten patients (11%) withdrew from the study during this time and eight (9%) in the subsequent 9 months because of drug-related side effects; five others (5%) withdrew for unrelated reasons. The incidence of adverse experiences was dose-related. Three patients reported unwanted effects on 10 mg three times daily, eight on 20 mg three times daily, 36 on 30 mg three times daily, and 12 on 40 mg three times daily oral nicardipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

Comparison of dietary hydrated copper sulphate, dietary zinc oxide and a direct method for inducing a moult in laying hens.

The experiment lasted for seven 28-d periods. Laying hens of two breeds were allocated to 10 treatments. For the first 28-d period all birds were offered the control diet and then the following dietary treatments applied: a control group not moulted, one group moulted traditionally, 4 groups moulted using CuSO4- and 4 using ZnO-containing diets. After the moulting treatments the hens were offered the control diet for the remainder of period 2 and for a further five 28-d periods. The treatments applied during period 2 significantly reduced food intake, body weight, egg number, total egg weight and efficiency of food conversion. On returning to the control diet, there were no significant differences in cumulative food intake (periods 3 to 7). Body weight had returned to the same value as the control group by the end of period 3. Dietary treatments significantly reduced the efficiency of food utilisation during periods 3 to 7 and 1 to 7 inclusive. For periods 1 to 7 inclusive the birds force-moulted using CuSO4 and ZnO gave on average greater egg numbers and total egg weights than those moulted traditionally. The Haugh unit score was significantly improved after moulting. Egg Zn concentrations were increased by the 14-d ZnO treatments. The use of a diet containing CuSO4 (2 g added Cu/kg for 7 d) was as effective as one containing ZnO (20 g added Zn/kg for 14 d) and both were superior to a traditional force-moulting technique.

Animals↗
PubMed1983

The effects of dietary intake and of dietary concentration of copper sulphate on the laying domestic fowl: effects on laying performance and tissue mineral contents.

Sixty white hybrid (Shaver 288) laying hens were subjected to three main dietary regimens for 5 d: ad libitum feeding of control and CuSO4-supplemented diets, force-feeding these same diets to the same intake as that of the ad libitum control diet and pair-feeding the control CuSO4-free diet to intakes equivalent to those of supplemented diets. Final body weight of the force-fed birds was significantly greater than of the other groups. Egg number and weight were significantly reduced as food intake decreased. Liver weight per unit body weight was significantly increased and oviduct and ovary weights/kg body weight were significantly reduced by force-feeding. As food intake decreased kidney and gizzard weights per unit body weight were significantly increased. The concentrations and total contents of Cu and Zn in liver were significantly increased in the ad libitum and force-fed groups. Force-feeding CuSO4-supplemented diets, which eliminated difference in food intake, confirmed that CuSO4 per se affected tissue weights and mineral concentrations as distinct from effects due to the reduced food intake associated with increasing dietary CuSO4.

Animals↗
PubMed1983

The effects of dietary intake and of dietary concentration of copper sulphate on the laying domestic fowl: effects on some aspects of lipid, carbohydrate and amino acid metabolism.

These investigations were carried out to determine whether the effects of feeding CuSO4-supplemented diets on metabolism in the laying hen were due directly to the dietary CuSO4 content or indirectly to the effects of CuSO4 on food consumption. In experiment 1, 144 hens were given CuSO4-supplemented diets ad libitum for 48 d. Food consumption decreased as the dietary CuSO4 content increased and this was associated with decreases in blood plasma lipid, 17 beta-oestradiol and liver lipid concentrations and hepatic lipogenic enzyme activities. In experiment 2, 60 laying hens were subjected to three dietary regimens in an attempt to differentiate between the effects of reduced food consumption and dietary CuSO4 per se. Control and CuSO4-supplemented diets were fed ad libitum, or the CuSO4-containing diets were force-fed to the same intake as the ad libitum control diet, or the control diet was pair-fed to the same intakes as the CuSO4-supplemented diets. Liver lipid concentrations were significantly decreased in the ad libitum and pair-fed groups at the lowest intake. Plasma 17 beta-oestradiol concentration was decreased in ad libitum and force-fed birds given diets with 1,000 mg added Cu/kg. Lipogenic enzyme activities were reduced in the ad libitum and pair-fed groups and increased in the force-fed birds. The results indicate that CuSO4 per se directly affected circulating 17 beta-oestradiol, and hence reproductive physiology, and that the quantity of food consumed influenced the rate of hepatic lipogenesis.

Amino Acids↗
PubMed1982

Time-course studies on the effects of oestradiol administration on the activity of some folate-metabolizing enzymes in chicken liver.

1. The specific activities of some enzymes of folate metabolism were measured in the liver of folate-treated and folate-deficient immature female chickens at intervals up to 9 days after an initial administration of 17 beta-oestradiol dipropionate. 2. An increase in dihydrofolate reductase activity after 3 days and decreases in 10-formyltetrahydrofolate synthetase and 5,10-methylenetetrahydrofolate dehydrogenase activities after 2 days became evident as a result of oestradiol treatment. 3. After 9 days, oestradiol caused a small decrease in glutamate formiminotransferase activity. 4. In folate-deficient chickens the activity of dihydrofolate reductase was decreased and that of serine hydroxymethyltransferase, 10-formyltetrahydrofolate synthetase and 5,10-methylenetetrahydrofolate dehydrogenase was increased in both non-hormone-treated and oestradiol-treated animals.

Animals↗
PubMed1982

The metabolism of [3',5',9(n)-3H] pteroylglutamic acid by chicken liver in vivo. Effects of folate deficiency and vitamin B12 supplementation.

1. Control, folate-deficient and vitamin B12-supplemented chickens were given [3', 5', 9 (n)-3H] pteroylglutamic acid by intraperitoneal injection. After various time intervals (1.5 h-8d) the incorporation of radioactivity into hepatic folate derivatives was measured. 2. The results confirm that avian species have a faster assimilation of folate than most mammalian species. 3. Folate deficiency increased the incorporation and retention of [3H] pteroylglutamic acid. The degree of folate conjugation was unaffected by folate deficiency but the formyl to methyl folate ratio was decreased. 4. Vitamin B12 supplementation had no effect on the uptake or conjugation of [3H] pteroylglutamic acid, but increased the formyl to methyl folate ratio.

Animals↗
PubMed1981

An attempt to distinguish between the direct and indirect effects, in the laying domestic fowl, of added dietary copper sulphate.

1. An experiment is reported in which the effects of giving copper sulphate-supplemented diets and control unsupplemented pair-fed diets to laying hens were compared. 2. The level of food intake significantly adversely affected mean body-weight, egg number, egg weight, liver, kidney, oviduct and ovary weights. Gizzard weight/kg body-weight was significantly increased both with decreasing levels of food intake and increased CuSO4 supplementation. 3. There was evidence of a depressing effect of CuSO4 per se on egg production and possibly on oviduct and ovary weight. 4. Liver lipid concentration was significantly decreased with decreasing levels of food intake and the results also suggest a depressing effect of CuSO4. 5. The Cu concentrations and total contents in liver and kidneys were significantly increased by dietary added CuSO4. Liver and kidney Zn and Fe concentrations were increased with decreasing levels of food intake rather than by CuSO4 addition.

Animals↗