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Biomedical subjects

A Hoffmann

Publications and source records attributed to A Hoffmann.

At least 397 records · Page 22Linked to original sources
PubMed1986

Additional data on Trypanosoma cruzi isozymic strains encountered in Bolivian domestic transmission cycles.

We have collected in Bolivia 212 stocks of Trypanosoma cruzi from domestic transmission cycles and have assayed for nine enzyme systems (11 gene loci). Only a few different isozyme profiles exist, without recombination between them, a situation also encountered in previous Bolivian samples. The 212 stocks, combined with 207 stocks previously studied, have been analysed to uncover any spatial patterns. The frequency of heterozygous strains (2 and 2a) decreases westwards and with increasing altitude. Given that longitude and altitude are correlated with each other, it is not possible to decide which of these two geographic variables is the relevant one, or if both are. These associations might be due to climatic factors. Studies by other authors have shown, however, that heterozygous strains are rare or absent in the Amazon Basin, which is at low altitude.

Altitude↗
PubMed1986

Exercise-induced ventricular tachycardia as a manifestation of flecainide toxicity.

A 32-year-old woman with prolapsed mitral valve was treated with flecainide because of an episode of primary ventricular fibrillation. The drug was chosen because several hundred short runs of ventricular tachycardia unrelated to exercise were observed during 24-hour monitoring. Oral medication at a dose of 200 mg twice daily suppressed all repetitive ventricular ectopy. Eighteen months later, however, a further 24-hour recording showed a ventricular arrhythmia which was provoked early in the morning by exercise. Because the tablets were taken late in the evening and early in the morning it was suspected that toxic levels of flecainide may have produced the arrhythmia. Measurement confirmed this suspicion. Reducing the dosage abolished the arrhythmia.

Adult↗
PubMed1986

Non-invasive grading of aortic regurgitation by Doppler ultrasonography.

Doppler ultrasound without concomitant echocardiographic imaging was used to grade isolated aortic regurgitation in 21 patients. The severity of aortic regurgitation was subsequently graded (from 0 to IV) angiographically. A 2 MHz continuous wave Doppler transducer was placed over the apex of the heart and the beam was aimed parallel to the mitral flow by means of acoustic guidance. Mitral pressure half time was calculated from the analogue maximum velocity tracing and it was less than or equal to 60 ms in 10 controls; 50-120 ms in five patients with grade II, 120-160 ms in nine patients with grade III, and greater than or equal to 160 ms in seven patients with grade IV aortic regurgitation. These results indicate that a semi-quantitative grading of aortic regurgitation may be obtained non-invasively with non-imaging Doppler ultrasonography in patients without concomitant mitral valve disease.

Adult↗
PubMed1986

[Stimulation of Brucella clearance in rats after treatment with BCG suspensions].

Intraperitoneal application of BCG induced a significantly increased clearance of Brucella in rats. The effect starts three days after application of 7 mg BCG to the rat and continued for eight weeks. This effect could be used for estimation of efficiency of BCG for nonspecific resistance stimulation. Comparative investigation of seven different batches reveals that three BCG preparations induce an unspecific resistance more than eight weeks, one for two weeks and three batches exerted no effect. Addition of Gelafusal as a stabilizer prolonged durability for about two weeks.

Animals↗
PubMed1985

[Use of Doppler ultrasound in cardiac diagnosis].

In cardiac diagnosis Doppler ultrasound provides quantitative data in the assessment of pressure gradient and valve area in stenotic lesions. In atrioventricular valves pressure half-time can be determined. In regurgitant lesions the only method capable of providing quantitative analysis of aortic regurgitation is calculation of forward-to-reverse flow ratio by multigate Doppler. All the other single-gate Doppler or 2-D-echo Doppler methods, such as LV or LA mapping, recording of impaired mitral flow and diastolic/systolic flow ratio, permit only semiquantitative assessment of regurgitant volumes. Finally, semiquantitative analysis of shunt volumes appears possible in children.

Child↗
PubMed1985

Blockade of a motor response by cholinergic stimulation of the toad midbrain tegmentum.

Application of an acid solution to the dorsal skin of conscious toads having intact nervous system induces a scratching reflex and escape movements, as well as autonomic alterations (hypertension and tachycardia) that are part of the defense response. The motor components of this response are abolished or reduced by microinjection of 60, 30, 15 or 7.5 ng carbachol into the midbrain tegmentum. The cardiovascular components, however, continue to be present, although their amplitude is reduced. The depression of the motor response is statistically significant up to 15 minutes for the 60 ng dose, up to 10 minutes for the 15 and 30 ng doses, and only up to 5 minutes for the 7.5 ng dose. The data suggest that the midbrain tegmentum may modulate the reflex motor response triggered by a noxious stimulus and also participate in the organization of the escape movements. The importance of cholinergic agents in this modulation is discussed. The persistence of the cardiovascular component of the response shows the importance of this parameter as an indicator of alert situations.

Animals↗
PubMed1985

Autonomic adjustments during avoidance and orienting responses induced by electrical stimulation of the central nervous system in toads (Bufo paracnemis).

Electrical stimulation of the central nervous system of conscious toads with permanently implanted electrodes in regions related to orienting and avoidance responses induces cardiovascular (hypertension and tachycardia) and respiratory (increased intrapulmonary pressure) changes together with the somato-motor effects typical of these responses. Sympathetic activation occurs and the main peripheral mediator involved may be adrenergic, since the cardiovascular effects are almost completely blocket by systemic pretreatment with phentolamine and DCI. The cardiovascular changes obtained by central stimulation are qualitatively similar to those recorded for toads whose orienting and avoidance behaviors are obtained by the presentation of visual stimuli (presentation of a prey and of a black card moved over the experimental box). Variations in heart rhythm may occur in both cases in the absence of visible somatic manifestations or of other neurovegetative changes, thus showing the importance of this parameter as an index of sensory reception of biologically significant stimuli. The results are compared to those obtained under similar conditions in other non-mammalian vertebrates.

Animals↗
PubMed1985

[Initial research on the use of mixed corn grain and stalk silage in broiler fattening].

The suitability of a corn and cob maize silage (CCM) as a component rich in energy in the fattening ration was investigated in a growth experiment with male broilers. The CCM silage with a dry matter content of 60.2% contained the following substances determining its value (per 1 kg dry matter of the feed): 102 g crude protein, 61 g crude fibre and 682 energetic feed units for chickens (EFUc). CCM silage was either fed as a component of a feed mixture consisting of 70.5% CCM silage and 29.5% protein concentrate (all values of original substance) or both components of the ration were fed to broilers separately. The protein concentrate was composed as follows (values per kg): 650 g soybean oilmeal, 110 g fishmeal, 85 g tankage from rendering plants, 55 g torula yeast, 70 g mineral mixture and 30 g of a mixture of biologically active substances. The broilers of the control group received commercial fattening feed for broilers with coarse maize meal as cereal component. The feed mixture with CCM silage and separate CCM silage were accepted readily. When CCM silage and protein concentrate were offered alternatively, the same amount of CCM silage was consumed but 8% less protein concentrate. The broilers fed with CCM silage plus protein concentrate reached 96-97% of the live weight of the control animals (1.952 g/animal, 49th day), which received conventional feed, although their net energy intake was 10% lower. This proves a more favourable net energy expenditure for the test groups fed with CCM silage.

Animal Feed↗
PubMed1985

Coronary artery bypass grafts. Influence of preoperative risk factors on the late postoperative course.

In order to assess the influence of preoperative risk factors on the late postoperative course, 186 consecutive patients in whom coronary artery bypass graft (CABG) was performed for chronic stable angina (169 men, 17 women, mean age +/- SD 54 +/- 8 years) were followed for an average of 54 (6 to 113) months. The overall five-year survival rate by life-table analysis was 90 +/- 2 percent. The postoperative course was considered favorable in 112 patients (60 percent) in whom angina was absent or improved by at least 2 NYHA classes throughout the entire follow-up, and was unsatisfactory in 74 patients. It was concluded that the late postoperative course of patients with CABG was unfavorably influenced by the presence of two or three risk factors, and a high preoperative cholesterol level was the only single risk factor associated with unsatisfactory outcome.

Adult↗
PubMed1985

Interaction of bilateral baroreceptor signals in conscious toads.

Unilateral electric stimulation of the central stump of one of the laryngeal nerves of conscious toads induced increases and falls in arterial blood pressure. The falls were more frequent when the contralateral laryngeal nerve was also sectioned. Simultaneous bilateral electric stimulation of the central stump of the laryngeal nerves induced hypotension in 45% of the animals and bradycardia in 28.5% of them, the magnitudes of the responses being equal to the sum of the responses obtained by individual stimulation of each nerve. In other animals, the hypotensive responses (55% of cases) resulting from bilateral stimulation exceeded by 60% the sum of the individual responses, and bradycardia (71.5% of cases) did so by 116%, i.e. potentiation occurred. Potentiation of the hypotensive response may be accompanied by potentiation or only summation of the heart rate response, and vice versa, showing that the two parameters are individually regulated. The possible mechanisms inducing these results are discussed in terms of the central organization of the circuits involved and of the interference of factors of a sensory nature present in unanesthetized animals.

Animals↗