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Biomedical subjects

J Kenny

Publications and source records attributed to J Kenny.

At least 19 recordsLinked to original sources
PubMed1991

Relationship between instantaneous trans-mitral blood flow velocity and instantaneous left ventricular volume in normal and hypertrophied hearts.

We examined the relationship between trans-mitral blood flow velocity and left ventricular volume in normal and hypertrophied hearts using cross-sectional Doppler echocardiography. We studied 10 normal subjects and 19 patients with left ventricular hypertrophy, 9 with aortic stenosis and 10 with dilated cardiomyopathy. Trans-mitral Doppler flow velocity signals and cross-sectional echocardiograms of the left ventricular short and long axes were digitized in each patient to obtain instantaneous mitral flow velocity, instantaneous left ventricular volume, left ventricular mass, and left ventricular mass/volume ratio at end-diastole. Peak velocities during rapid filling (E wave) were similar in all three groups. Peak velocities during atrial systole (A wave) were significantly increased in aortic stenosis, (124 +/- 28 cm/sec); but were not different from normal in dilated cardiomyopathy (43 +/- 20 cm/sec versus 32 +/- 9 cm/sec). The peak A/E velocity ratio was elevated in aortic stenosis 1.47 +/- 0.30, but in dilated cardiomyopathy it was similar to normal hearts (0.47 +/- 0.23 versus 0.54 +/- 0.15). The percentages of left ventricular filling achieved at the time of the peak E wave, the end of rapid filling, and at the time of the peak A wave were similar in all three patient groups. There was no correlation between blood flow velocities at peak E wave, peak A wave or the A/E velocity ratio and left ventricular volume or mass. There was a significant correlation between peak A velocities and left ventricular muscle/cavity areas (r = 0.81; P less than 0.001). There was a similarly close correlation between the peak A/E velocity ratios and left ventricular muscle/cavity areas (r = 0.80; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

An ivermectin sustained release bolus in cattle: its effects on the tick Ixodes ricinus.

Five calves were given an intraruminal bolus orally, designed to release ivermectin for 120 days at the rate of 8 mg/day. This is equivalent to a dose of 40 micrograms/kg/day for a calf expected to weigh 200 kg at the end of the delivery period. Five control calves were given a placebo bolus. On days 7 and 36 after treatment ten nymphs and ten adult female Ixodes ricinus (Linnaeus 1758) were placed in ear bags on the calves. The engorgement rates were monitored for 10 days and subsequent egg production and hatching percentages determined. There were no significant differences between treatment groups for female mortality. However, ivermectin treatment significantly reduced the numbers and weights of engorged females, females laying eggs, and the number of larvae produced on the treated calves was reduced to 3% of that of the control group. The effects on nymphs, although similar, were less consistent than on adults.

Administration, Oral↗
PubMed1988

Uro-radiological manifestations of pancreatic carcinoma.

Two patients are described who suffered from pancreatic adenocarcinoma. These had extended to involve the urinary tract. One patient presented with haematuria from renal metastases. The other was diagnosed following the incidental discovery of a hydronephrosis by radionuclide bone scintigraphy. The radiological changes in these patients are described.

Adenocarcinoma↗
PubMed1987

Doppler echocardiographic evaluation of ring mitral valvuloplasty for pure mitral regurgitation.

Doppler echocardiographic studies were performed in 21 consecutive patients (mean age 56 +/- 11 years) to evaluate postoperative results of mitral ring anuloplasty. All patients were symptomatic and all had clinically severe isolated mitral regurgitation (MR). The origin of MR was myxomatous degeneration, coronary artery disease, rheumatic heart disease or congestive cardiomyopathy. In 20 patients ring anuloplasty was performed using the Carpentier ring and 1 patient using the Duran ring. Postoperative Doppler echocardiographic studies were performed to detect and semiquantitate residual MR by flow mapping and to identify left ventricular inflow or outflow obstruction. The severity of MR was assessed by flow mapping in the left atrium and graded from I to IV in increasing severity. Blood flow velocity spectra were recorded from the left ventricular outflow tract during systole and from the left ventricle subjacent to the mitral valve during diastole. Pressure half-time, mitral valve area and mitral valve gradient were derived from digitized mitral diastolic flow velocity spectra. After ring valvuloplasty, 9 patients had no MR and 6 had grade I, 3 grade II, 2 grade III and 1 patient grade IV MR. Peak diastolic mitral valve gradient was 8 +/- 4 mm Hg, mean diastolic gradient was 3 +/- 2 mm Hg and pressure half-time was 83 +/- 17 ms, representing a calculated mean mitral valve area of 2.9 +/- 0.8 cm. Peak velocity in the left ventricular outflow tract was 0.9 +/- 0.2 m/s, indicating no obstruction to outflow. Our study confirms that mitral ring valvuloplasty produces a significant reduction in severity of MR, and this is achieved without obstructing left ventricular inflow or outflow.

Adult↗
PubMed1987

Effects of heart rate on ventricular size, stroke volume, and output in the normal human fetus: a prospective Doppler echocardiographic study.

The effect of heart rate on cardiac output in the fetal heart is controversial. We used Doppler echocardiography to investigate the effects of increasing heart rate on stroke volume and ventricular output in the normal human fetal heart. Heart rate was increased in 25 human fetuses (mean age 36 weeks) by auditory stimulation with a sound emitter placed on the mother's abdomen. Aortic or pulmonary diameters were measured at valve level from two-dimensional echocardiographic images and cross-sectional areas were calculated. Blood flow velocity spectra from the pulmonary artery or aorta were digitized to obtain flow velocity integrals before and after auditory stimulation. Stroke volume was calculated as the product of the flow velocity integral and the area of the great vessel. Prestimulation mean heart rate was 132 +/- 8 beats/min and increased after auditory stimulation to 158 +/- 9 beats/min (p less than .001). Stroke volume decreased with the increase in heart rate from 3.7 +/- 1.4 ml before stimulation to 3.0 +/- 1.1 ml after stimulation (p less than .001), but ventricular output calculated as the product of stroke volume and heart rate remained unchanged (0.48 +/- 0.18 liter/min before vs 0.48 +/- 0.17 liter/min after stimulation). The decrease in stroke volume was accompanied by a decrease in ventricular end-diastolic area, although there was no change either in end-systolic area or fractional change in area. This study demonstrates that increases in heart rate within the physiologic range in the normal human fetus result in a decrease in ventricular size and stroke volume but no change in ventricular output or ventricular shortening.

Cardiac Output↗
PubMed1986

Inhibition of Babesia divergens in cattle by oxytetracycline.

The effects of continuous oxytetracycline administration on the development of parasitaemia of Babesia divergens during both natural and artificial infections were studied. During natural exposure on grazing heavily infested with Ixodes ricinus, seven out of 42 cattle with no previous exposure to tick-borne diseases were injected every four days with a long acting preparation of oxytetracycline at a dose rate of 20 mg/kg. During the six week grazing period 21 untreated cattle developed a patent parasitaemia of B divergens and all became seropositive by the fluorescent antibody test. In contrast, no parasites were observed in treated cattle and antibody titres remained low. Artificial infections were studied with different dose levels of oxytetracycline and their effects on antibody stimulation noted. First, four groups of cows were infected with 10(8) erythrocytes infected with B divergens, three groups being injected every four days with the long acting oxytetracycline formulation at dose levels of 20, 10 and 5 mg/kg, respectively. The highest level completely inhibited parasite replication and antibody formation; the same was observed in one animal dosed at 10 mg/kg but the remainder, plus those treated at 5 mg/kg, developed both low parasitaemia and high antibody titres. The untreated cows developed severe babesiosis. A further untreated control group was added and three weeks after cessation of oxytetracycline treatment all were infected with 10(9) erythrocytes infected with a homologous isolate of B divergens. The controls, plus those in which the previous infection had been completely inhibited, developed severe clinical babesiosis but the remainder were refractory to parasite development.

Animals↗
PubMed1986

Babesia divergens: sequential exposure to heterologous tick-borne challenge of cattle immunized with a fraction of parasitized erythrocytes.

Two groups of cows previously unexposed to ticks or tick-borne infections were immunized with an acidic fraction, isolated by isoelectric focusing, of a lysate of a laboratory strain of Babesia divergens infected erythrocytes 5 months and 1 month before grazing on a pasture harbouring a large population of ticks known to transmit babesiosis. Both treated groups and the untreated became infected with a field strain of B. divergens after 19 of the 21 cattle (3 groups of 7) had first developed tick-borne fever. All those immunized one month and 6 of 7 immunized 5 months previously resisted lethal multiplication of B. divergens whereas 4 of 7 controls required treatment to prevent their deaths. There were significant differences between the groups in the magnitude of parasitaemia; reduction of packed cell volume and antibody titres is an indication that the pre-treatment with the acidic fraction of the laboratory strain had induced significant protection against the heterologous field strain. Problems in the field use of a babesial vaccine include concomitant field infection with tick-borne fever, the need for a suitable adjuvant and a study of lysates of different strains of B. divergens.

Animals↗
PubMed1986

Isolation of antigenic proteins from erythrocytes parasitised with Babesia divergens and a comparison of their immunising potential.

Soluble proteins present in the supernatant prepared from a sonicated lysate of concentrated erythrocytes infected with Babesia divergens were separated by isoelectric focussing into acidic and non acidic fractions. The acidic fraction was further separated by passage through Concanavalin A Sepharose (Con A) into two fractions, the first (Fraction 2) consisting of proteins plus one glycoprotein which did not bind to Con A, the second of glycoproteins (Fraction 1) which were eluted after binding to Con A. One group of six cows was treated with three injections of Fraction 2 with incomplete Freunds adjuvant (IFA); two other groups received the same number of injections of Fraction 1, one with IFA, the other with glucan as adjuvant. These cows plus an untreated control group were infected with 10(5) erythrocytes infected with a heterologous isolate of B. divergens. Only the group treated with Fraction 2 (Group 1) resisted lethal multiplication of the parasite. There were significant differences in magnitude of parasitaemia, reduction of packed cell volume and antibody titres between Group 1 and the other groups.

Animals↗
PubMed1985

Comparison of early season suppressive anthelmintic prophylactic methods for parasitic gastroenteritis and bronchitis in calves.

A comparison was made of the material costs and effectiveness of three methods of early season suppression by anthelmintic medication of Ostertagia species and two of Dictyocaulus viviparus in calves, each method suppressing faecal egg output for different lengths of time from the start of spring grazing. The anthelmintics used were: Morantel bolus administered five days before going to grazing; oxfendazole given three times at three, six and nine weeks after the start of grazing and ivermectin injected three, eight and 13 weeks after going to pasture. The effectiveness of each was estimated by comparison with worm numbers in untreated control calves. Oxfendazole, which was active for the shortest time (about 65 days) from the start of grazing (May 1), produced a 78.1 per cent reduction in Ostertagia species and an 84.4 per cent reduction in D viviparus. The morantel bolus was estimated to be active for 90 days and resulted in a 94.3 per cent reduction of Ostertagia species. The ivermectin treatment, which, because of the prolonged excretion of the chemical and different sensitivity of worm species, was estimated to suppress Ostertagia species for 105 days and D viviparus for 119 days, caused reductions of 98.7 per cent of the former and 97.4 per cent of the latter species. Material costs per calf were estimated at pounds 1.25 for oxfendazole, pounds 2.00 for ivermectin and pounds 10 for the morantel bolus.

Animals↗