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Biomedical subjects

H Engelbrecht

Publications and source records attributed to H Engelbrecht.

At least 19 recordsLinked to original sources
PubMed2004

Changes in the renal handling of urea in sheep on a low protein diet exposed to saline drinking water.

Previous trials have demonstrated that sheep on a low protein diet and free access to water, and sheep dosed with boluses of NaCl intraruminally also with free access to water, showed decreases in urea loss via the urine compared to control animals. We monitored urea excretion in sheep on a relatively poor protein diet when they were exposed to saline drinking water, i.e. they were unable to vary their intake of NaCl:water. Sheep on isotonic saline drinking water (phase 3) excreted significantly more urea via the urine (284 mM/day) compared to phase 1 when they were on non-saline drinking water (urea excretion = 230 mM/day) and phase 2 when they were on half isotonic saline drinking water (urea excretion = 244 mM/day). This finding was explained by the high glomerular filtration rate (GFR) 91.9 l/day, compared to 82.4 l/day (phase 1) and 77.9 l/day (phase 2), together with a significantly raised fractional excretion of urea (FEurea) (51.1 %) during this phase, and was in spite of the significantly lower plasma concentrations of urea in phase 3 compared to phase 1. The FEurea probably results from the osmotic diuresis caused by the salt. There were indications of a raised plasma antidiuretic hormone (ADH) concentration and this would have opposed urea loss, as ADH promotes urea reabsorption. However, this ADH effect was probably counteracted to some extent by a low plasma angiotensin II concentration, for which again there were indications, inhibiting urea reabsorption during the phases of salt loading. As atrial natriuretic peptide both increases GFR and decrease sodium reabsorption from the tubule, it was probably instrumental in causing the increase in GFR and the increase in the fractional excretion of sodium (FE(Na)).

Animals↗
PubMed1999

The effect of an angiotensin-converting enzyme inhibitor on water and electrolyte balance in water-restricted sheep.

The importance of angiotensin II in the regulation of water and electrolyte balance in sheep is questionable. In this trial the effects of an angiotensin-converting enzyme (ACE) inhibitor were quantified in sheep on restricted water intake. Comparing the phase of water restriction only with that of water restriction plus ACE inhibition, significant increases were observed during the latter phase in urine volume, sodium and potassium excretion via the urine, sodium concentration in the plasma and osmolar clearance. Urine osmolarity decreased with inhibition of angiotensin II formation while variables such as water, sodium and potassium loss via the faeces were unaffected. Most of the renal effects of ACE inhibition, except the increase in urinary potassium excretion, were explicable in terms of the established functions of angiotensin II. Furthermore, results of this trial indicate that angiotensin II has no significant effect on the intestine in regulating water and electrolyte excretion via the faeces.

Angiotensin II↗
PubMed1998

Numerical simulation of pulsating flow in the aortic arch.

In order to investigate the flow profiles in the aorta a numerical three-dimensional model of the aortic arch was created. The velocity fields were simulated by applying an inlet velocity corresponding to the physiological velocity of the pressure wave at the aortic valve. The velocity field distribution was found to be uniform throughout the model during the time of increasing inlet velocities. With decreasing inlet velocities a region of low flow developed in the descending portion of the model leading to recirculating flow at the inner wall. At this region of low flow the variation in velocity with time at the inner wall was approximately twice the variation at the outer wall. As a result of the recirculating flow, the wall shear stresses at the inner wall are low and oscillating, predisposing to the development of atherosclerosis. This model shows that transient fluid flow in the aortic arch can be simulated. Biological studies are needed to prove that this model can be used to predict sites of pathology.

Algorithms↗
PubMed1993

Changes in kidney function and faecal excretion of water and electrolytes with sodium chloride loading in sheep.

The renal and faecal routes of water and electrolyte excretion in sheep were compared and changes in kidney function assessed when similar amounts of sodium chloride (NaCl) were dosed in free and fixed ratios in water. Sheep (n = 6) either had free access to fresh drinking water (control phase) or 0.9% saline drinking water, or NaCl was dosed intraruminally with free access to fresh drinking water. In the final phase of the investigation, sheep were dosed intraruminally with NaCl while water intake was restricted. Variables monitored included fresh or saline water intake, water, sodium and potassium loss via the urine and faeces, glomerular filtration rate (GFR), fractional excretions of sodium (FENa) and potassium (FEK) and solute free water clearance (CH2O). Results indicated that where NaCl intake was high, sodium excretion via the urine was of far greater importance than that via the faeces and that changes in kidney function which occurred in order to excrete excess sodium, included increases in GFR and FENa, and declines in FEK and CH2O. Where significant differences were obtained in variables between the phases of high salt intake, these were attributed to differences in sodium absorption from the gastrointestinal tract. It was concluded that when NaCl intake is high, sodium homeostasis is chiefly maintained by increasing the amount of sodium made available to the nephron tubule (increased GFR), by decreased tubular reabsorption of this sodium and by increasing solute free water reabsorption.

Animals↗
PubMed1991

[The eggs of Enterobius vermicularis in room dust. I. Methods].

Results of anal swabs have been compared with room dust samples. The room dust was collected using little brushes as well as a vacuum cleaner from a standard surface of 0.25 m2. To collect room dust by vacuum cleaner, a slide was placed into a special chamber, connected to an absorbing device. Eggs of E. vermicularis have been found in samples made with anal swabs, room dust brushes and the vacuum cleaner, respectively, as follows: in the first examination 34%, 17.4% and 25.1%, in the second examination 35%, 17.7% and 15.7% and in the third examination 42%, 15.7% and 35.4%.. The results are discussed with regard to methodical and epidemiological aspects of the examination eggs of E. vermicularis in room dust.

Anal Canal↗
PubMed1990

[Staging the psychoanalytic situation in supervision].

Fantasies, parapraxes, and associations that figure significantly in the transference-countertransference process between patient and analytic candidate also work their way into the relationship between the candidate and the supervisor--sometimes in disguised fashion. The author illustrates this observation with vignettes and shows how, with the help of Lorenzer's concept of scenic understanding, the interaction pattern observable in the supervision can be utilized for the understanding of the material presented by the patient.

Countertransference↗
PubMed1988

[Scanning electron microscopic representation of the tegument of the cysticercus of Taenia saginata].

By scanning electron microscopy we found heteromorph microtriches in the tegumental surface of the praeadult and its bladder. But this polymorphism is caused by three unimorph parts, namely the head region, the midbody and the bladder. The types of microtriches are heterogeneous in regard to the shape (from conical to cylindrical), the size (from 0.37 to 4.5 micron in length and 0.055 to 0.092 micron in diameter) and the density (from 6.3 to 25 microtriches/micron 2). An attempt was made to determine the relative increase in the tegumental surface of the cysticercus of T. saginata. The relation of actual surface area to a corresponding area without microtriches is OF = nA + 1/1 - nB. In this study, the factor of the increase in the tegumental surface (OF) ranged from the head region (6.3x) to the midbody (1.4x -1.7x) and the bladder (21x). By transmission electron microscopy fine threads were demonstrated in the apical surface of the microtriches. These fine threads raised the adhesive function of the microtriches in the course of the infection of the final host as well as in the migration in the digestive tract. A relation between shape, size and density of the microtriches and the body volume is postulated.

Animals↗
PubMed1984

[Taenia saginata, a historical, ecological and epidemiological study].

Taenia saginata, considerations on the history of discovery, on ecology and epidemiology. The influence of urbanisation on the distribution of Taenia saginata has been investigated. It seems suitable both from ecological and epidemiological aspects to divide the life cycle of T. saginata in a primary, direct cycle ( biotop type I), and a secondary, indirect cycle (biotope type II). The two adjectives (direct and indirect) denote the routes of transportation of taeniid eggs to cattle as well as of metacestodes to man. In the secondary cycle the contact between man and cattle or vice-versa is stopped owing to artificial biotop elements. There is a development of cycles closing themselves in a large territory and of transregional open infection chains. The totality of these infection chains shapes the life cycle. The secondary cycle is defined as "urban host-changing cycle" of T. saginata. The degree of sewage clarification is responsible for the incidence of infection with bovine cysticercosis. The conclusions are illustrated by 3 diagrams.

Animals↗
PubMed1984

[Urban alternate host cycle of Taenia saginata in Wittstock County, district of Potsdam (East Germany)].

The urban alternate host cycle of Taenia saginata in the county of Wittstock, district of Potsdam (GDR). Investigations of the epidemiology of bovine cysticercosis and human taeniasis were carried out in the county of Wittstock from 1979 till 1980. The analysis was based on the examination of human faeces, sewage and sewage sludge, the registration of infested humans, anticestodica consumption, number of infested cattle, areas for squirting out sewage, fodder supply areas and location of cattle. These data were mapped. There is a direct connection between the prevalence of Cysticercus bovis in more than 50 per cent of the infested cattle of the county of Wittstock and the squirting out of the sewage of the county town. 21 to 27 million Taenia eggs per day get into the waste-water purification plant. The proportion of infested humans and infested cattle is 1: 250 or 1: 290, respectively. The prevalence of adult tapeworms is 0.008-0.18%, and that of cysticerci is 20%.

Animals↗
PubMed1984

[Fine structure of the bladder tegument of Taenia saginata metacercaria with reference to establishment in the final host].

The ultrastructure of the bladder tegument of the metacestode of Taenia saginata, with considerations on the establishment in the definitive host. The tegument surface of invaginated Taenia saginata metacestodes was demonstrated by scanning electron micrograph. The tegument is folded irregularly and its surface is amplified by the presence of microtriches, 44-45 microtriches/micron 2. The microtriches are about 500 nm long and have an absorptive function. Likely, form and sensity of microtriches turn out a capillary attraction that plays an important role in contact with surface (finger, tongue and duodenum of man, instrumentarium , glass, plastics). This opinion is supported by scanning electron micrograph of the surface of finger-tips, of the tongue and the duodenum of man.

Animals↗
PubMed1983

[Test of the vitality and infectiousness of the beef tapeworm (Cysticercus bovis)].

The vitality and infectiosity of Cysticercus bovis can be determined by means of a relatively simple in vitro method. Mobility and evagination are 2 parameters for estimating vitality as well as infectiosity. The mobility-evagination-relationship (MER) is an excellent basis for investigating the mobility over 20 h, because 2 parameters are involved. Of special interest was the fact that the first part of MER (after 1 h) is the period for the short-time-test (control of vitality), and the second part of MER (after 18 to 20 h) is the period for the long-time-test (control of infectiosity). Mobility and evagination of metacestodes were tested in activator solution (100 ml physiological saline + 6 ml fresh swine bile) at a temperature of 38 degrees C and a pH of 7.0. This in vitro method may be useful in determining the vitality of fresh and older Cysticercus bovis and of those exposed to smoking.

Animals↗
PubMed1983

[A model of cockroach control in a large area. II. Occurrence and distribution of Blattella germanica and Blatta orientalis in the district of Potsdam (GDR)--an infestation analysis].

Blattella germanica and Blatta orientalis occur in the district of Potsdam (German Democratic Republic). B. germanica is the real cause of plague. Up to now 2,734 building properties have been infested with cockroaches. B. germanica was found in 2,644 properties; B. orientalis was found in 20 properties and both were found in 70 properties. Infestation with cockroaches increases with urbanisation. Infestation is especially frequent in works canteens and similar rooms. Outdoor distribution of cockroaches takes place passively in food transports. Inside buildings cockroaches spread through cracks in walls, through pipings, lift shafts etc. 70 to 80% of the properties infested by cockroaches are works canteens, shops, restaurants, hotels and bakeries. B. germanica was found in 82% of the larger hospitals and outpatients' clinics, in about 72% of the works canteens, in about 26% of the restaurants and hotels, in about 20% of the bakeries and the enterprises manufacturing beverages, in 17% of the shops, in 8.8% of the nurseries and crèches and in a smaller percentage in flats and newlybuilt residential areas.

Animals↗