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Biomedical subjects

H Hackbarth

Publications and source records attributed to H Hackbarth.

At least 19 recordsLinked to original sources
PubMed1995

A study on the prevention of prenatal and galactogenic Toxocara canis infections in pups by treatment of infected bitches with ivermectin or doramectin.

Investigations were carried out to test the efficacy of a two dose treatment with ivermectin or doramectin on reactivated larvae of Toxocara canis in bitches to prevent prenatal and galactogenic infections of their pups. Thirty pregnant bitches were treated by subcutaneous injection of ivermectin or doramectin on day 40 and 50 post conception (p.c.) each with a dose of 1 mg/kg body weight. The efficacy of the treatments was determined by faecal examinations and by comparing the number of infected pups and the onset of patency in each group of pups. 1. Patient infections with T. canis were seen in pups from untreated bitches from day 21 after birth and all pups were coproscopically positive one week later. To prevent severe clinical symptoms all pups in this group were treated with anthelmintics on day 42 after birth. 2. Pups from ivermectin treated bitches occasionally exhibited patent infections from day 28 after birth onwards; pups from doramectin group exhibited infections from day 56 after birth. The number of patently infected pups in both groups increased till 70 days after birth, probably because of postnatal infections. 3. 28 days after parturition, T. canis infections became patent in all untreated bitches. Single bitches in the ivermectin and doramectin groups developed patent infections after day 49 after parturition. All coproscopically positive bitches had patently infected pups in their litters. 4. The contamination of the environment with eggs of T. canis was calculated from the results of the faecal examinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Morphometric studies of the proximal tubules of the rat kidney considering the effect of the method of killing].

120 male rats belonging to two different strains (Han: WIST, Han: SPRD) and two different weight groups (group I: lighter body weight, group II heavier body weight) were killed on three different methods (decapitation, Nembutal -overdose greater than 250 mg/kg b.w. i.p. less than, exsanguination in Nembutal -anaesthesia greater than 100 mg/kg b.w. i.p.). Subsequently, changes in tubuli contorti I of the left kidneys were examined morphometrically. The mean total area, luminal area and epithelial area were evaluated as well as the mean diameter of the tubular nuclei. Concerning the areas of the proximal tubules only the luminal areas show differences between the Wistar and the Sprague-Dawley strain. The total, luminal and epithelial area in the rats belonging to the weight group II were significantly larger than in the rats belonging to weight group I. With one exception this could be noticed within both strains and all three modes of killing. In both strains and weight groups the rats were killed by Nembutal -overdose or exsanguination showed significantly smaller total, luminal and epithelial areas than the rats that were decapitated. Possible cause heretofore are discussed. Differences between the tubular areas of the rats that were killed by Nembutal -overdose and those that were killed by exsanguination after Nembutal -anaesthesia could not be established. The measurements of nuclei diameters in the proximal tubules did not lead to clearly different results between both strains, weight groups and the various modes of killing.

Animals↗
PubMed1989

[Animal welfare relevance and the functional and morphological significance of the killing of laboratory animals].

Euthanasia of experimental animals at the end of an experiment or when an experiment is terminated is relevant for two reasons: firstly, because of ethical reasons and of animal protection, secondly because of scientific evaluation of experimental results. Functional and morphologic alterations have up to now been inadequately observed and considered. Gradually varying different results depend on the different methods of euthanasia. Additionally single parameters of reactions in isolated organs vary depending on the method of euthanasia. These facts have not yet been respected in the discussion of so called alternate methods. The significance of functional and morphologic effects as seen in different methods of euthanasia is discussed with examples.

Animal Welfare↗
PubMed1986

Phase evaluation in hypothetical receivers simulating ranging in bats.

Echo delay discrimination by the bat Eptesicus fuscus had been investigated in an experiment with simulated targets jittering in range (Simmons 1979). The dip in the resulting psychometric curve was used by Simmons to suggest the neuronal implementation of a coherent cross-correlation receiver in the auditory system of bats. By computer simulation it is shown here that the dip may be even more pronounced and less susceptible to noise with alternative receiver configurations which not necessarily evaluate signal phase information coherently, e.g., a bank of neuronal filters with envelope-processing. New behavioral experiments are suggested to critically test such model hypotheses.

Acoustic Stimulation↗
PubMed1986

Accuracy of distance measurement in the bat Eptesicus fuscus: theoretical aspects and computer simulations.

Behavioral experiments of Simmons [J. Acoust. Soc. Am. 54, 157-173 (1973) and Science 204, 1336-1338 (1979)] on the ranging accuracy in the bat Eptesicus fuscus have led to far-reaching postulates on the existence of optimal and phase-conserving processing mechanisms in the bat. In this paper, the results of computer simulations of these experiments are presented. Two receiver types are investigated: the fully coherent cross-correlation receiver and the cross-correlation receiver with envelope processing (semicoherent). It is shown that Simmons' experiments cannot be treated as a simple estimation of distance, but require at least two (range difference experiment; see Simmons, 1973) or four (range jitter experiment; see Simmons, 1979) echolocation sounds for one decision. The performance of the bat in both experiments is much worse than predicted for a coherent and a semicoherent receiver type. The bat's accuracy in Simmons' range difference experiment is at least 18 dB worse than predicted for an optimal receiver. The results of the jitter experiment cannot be interpreted in a simple way as proof that bats are able to evaluate phase information as in a fully coherent cross-correlation receiver.

Animals↗
PubMed1985

Species and strain differences in urinary protein excretion.

The physiological excretion of urinary protein is subject to great variation influenced not only by environmental and hormonal factors but also by genetics. The present study demonstrates that there is not only variation in respect to the excretion of plasma proteins but also of other types of proteins which are specific urinary proteins. There is a close relation between body weight and total protein excretion. However, male rats and mice do not fit the allometric line calculated for the other species studied. This is of special importance since these two species are often used in kidney research. The reason for this divergence in total protein is the excretion of sex-dependent low molecular weight proteins. The excretion of albumin, which is a marker of glomerular permeability and tubular reabsorption as well, shows a marked genetic variation between different rat strains. The data presented in this study demonstrate the general admissibility of transferring data from one species to the other but also the limitations in respect especially to the sex-dependent proteins which are excreted by some species.

Analysis of Variance↗
PubMed1984

Blood pressure in rats: a comparison of a multifactorial experimental design to measurements in an outbred stock.

Systolic blood pressure was measured in males of 8 inbred strains and 1 outbred stock of rats 5 times over a period of 20 min on 5 consecutive days. The strain means ranged between 107.9 mmHg and 149.3 mmHg. The estimated variance between strains (V = 248.7 mmHg) was about 5 times higher than the variance within strains (V = 54.3 mmHg). The intraindividual variance within strains was relatively constant (V = 24.0-37.6 mmHg), while the interindividual variance varied to a great extent (V = 4.5-44.5 mmHg) from strain to strain. The outbred stock showed values of blood pressure and components of variance similar to those of a single inbred strain. Thus, by investigation of a battery of 8 inbred strains in a multifactorial experimental design a greater phenotypic variability due to genetic strain differences is achieved than by measurements in a single outbred stock.

Analysis of Variance↗
PubMed1983

Distribution of glomeruli in the renal cortex of Munich Wistar Frömter (MWF) rats.

The glomerular distribution in the renal cortex of the Munich Wistar Frömter (MWF) rat, a substrain of the Munich Wistar rat selected for superficial glomeruli, was compared to that of a control strain (LEW/Ztm) between 10 and 150 days of age. While there were no significant differences in body growth, kidney weight, or growth of the renal cortex in these two strains, the average diameter of Bowman's capsule and of the glomerular tuft was significantly larger (about 12%) in rats of the MWF strain which were older than 60 days. In histological sections of kidneys of MWF rats in all age groups, many glomeruli in direct contact with the renal capsule were found; thus, this developmental step must have taken place before 10 days of age. The appearance of superficial glomeruli was due to a shift of glomeruli to a position just under the renal surface, the subcapsular zone or 'cortex corticis', which is normally free of glomeruli. For the rest of the renal cortex there were only slight differences in glomerular density and in total number of glomeruli per section between these two strains. These results lead us to suppose that superficial glomeruli belong to a special nephron type; thus, these glomeruli are not enveloped by parts of the proximal tubule.

Animals↗
PubMed1983

Strain differences in inbred rats: influence of strain and diet on haematological traits.

5 inbred strains of rats maintained on 3 commercial pelleted diets were investigated for differences in haematological traits on the 154th day of age. Number, size and haemoglobin content of the erythrocytes were shown to be strongly influenced by strain and diet. While the strain AS/Ztm was always found in a high position within the ranking order of strains, the strain DA/Ztm was always found in a low position. For nearly all haematological traits, diet II (Altromin C1000) resulted in the highest values. This was not due to a difference in the content of iron (Fe), because even though diet III (Altromin 1534) contained only 50% of the Fe in diet I (Altromin 1324), differences between these two diets were small. Significant interactions between strain and diet were shown to exist for the mean corpuscular volume (MCV) and the mean corpuscular haemoglobin (MCH). Strong genetic correlations were found between haematocrit (HCT) and haemoglobin (Hb) and between MCV and MCH, while the number of red blood cells (RBC), Hb, HCT, MCV and MCH correlated significantly within each strain. However, these environmental correlations have to be interpreted with caution, because these variables are not determined independently.

Animal Feed↗
PubMed1982

Changes with age in renal function and morphology in C57BL/6, CBA/HT6, and B6CBAF1 mice.

Mice of the C57BL/6J and CBA/HT6J inbred strains and their F1 hybrid were investigated at 67, 202, 463, and 711 days of age to determine how genetic differences affected aging patterns of renal function and morphology. The three genotypes differed significantly in their body and kidney weights and their kidney to body weight ratios. These differences reflected functional capacities, and renal hypertrophy appeared to be an attempt to compensate for functional losses with age. The glomerular filtration rate (GFR) decreased in both inbred strains with age but remained constant in the F1 hybrid mice. There was a significant strain difference in GFR, but this difference disappeared when the GFR was considered in relation to the kidney weight. Thus the strain difference appeared to reflect differences in ability to compensate for loss of function by increasing kidney size. Osmolarities and sodium clearances decreased with age and increased with renal hypertrophy, but plasma levels were constant. Histopathological changes with age appeared to be correlated with functional changes.

Aging↗
PubMed1982

Intraspecies allometry: correlation between kidney weight and glomerular filtration rate vs. body weight.

Allometric equations of the form of Y = a*BWb were calculated between body weight (BW) on the one hand and either kidney weight (KW) or glomerular filtration rate (GFR) on the other. By using strain and sex means obtained from 24 different inbred strains of adult mice or F1-hybrids environmental and genetical influences could be separated statistically. Thus, allometric equations reported in this study describe exclusively genetic influence. The parameters for intraspecies allometric equations obtained in these studies were compared to those in the literature presenting interspecies relationships. The double logarithmic regressions of KW vs. BW gave results different from the interspecies equation. The difference between intra- and interspecies results of allometric relationships may be due to the experimental exclusion of environmental influences. The regression parameters for GFR vs. BW obtained for the inbred strains, however, agreed very well with those of the empirical equation for interspecies relationship and also with the theoretically expected value. The dependence of GFR on BW was found to be GFR = 0.036*BW0.74 +/- 0.15, where GFR is measured in ml/min and BW in g. The exponent of 0.74 seems to be a valid biological constant that is genetically determined within and across species lines.

Animals↗
PubMed1982

The renal clearance of albumin following intravenous loading of homologous albumin in conscious rats.

Tubular reabsorption of albumin was studied in conscious rats by measuring the renal excretion at various plasma concentrations. The plasma albumin concentration was raised by loading the animals with homologous serum albumin. By using this procedure an average plasma concentration of 54 g/l could be reached, which is about twice the physiological plasma albumin concentration in untreated rats. Throughout the experiments the glomerular filtration rate was determined by the total plasma slope clearance of 51Cr-EDTA. Following the albumin load, the 51Cr-EDTA clearance remained at 54.8 +/- 12.2 ml/min/m2 body surface. By correlating renal albumin excretion and plasma albumin concentration, the sieving coefficient of albumin, phi, of 2.35 x 10(-4), the renal albumin threshold of 38 +/- 5 g/l, and the maximal tubular transport rate of albumin of 9.6 +/- 2.6 micrograms/min/g kidney weight could be calculated (mean +/- SD). There were some variations among the animals, resulting in a fairly large standard deviation. However, these values are in agreement with recent micropuncture data.

Animals↗