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Biomedical subjects

M T Frankenhuis

Publications and source records attributed to M T Frankenhuis.

At least 19 recordsLinked to original sources
PubMed1999

Isolation and partial characterization of a lentivirus from talapoin monkeys (Myopithecus talapoin).

We have identified a novel lentivirus prevalent in talapoin monkeys (Myopithecus talapoin), extending previous observations of human immunodeficiency virus-1 cross-reactive antibodies in the serum of these monkeys. We obtained a virus isolate from one of three seropositive monkeys initially available to us. The virus was tentatively named simian immunodeficiency virus from talapoin monkeys (SIVtal). Despite the difficulty of isolating this virus, it was readily passed between monkeys in captivity through unknown routes of transmission. The virus could be propagated for short terms in peripheral blood mononuclear cells of talapoin monkeys but not in human peripheral blood mononuclear cells or human T cell lines. The propagated virus was used to infect a naive talapoin monkey, four rhesus macaques (M. mulatta), and two cynomolgus macaques (M. fascicularis). All animals seroconverted and virus could be reisolated during a short period after experimental infection. A survey of SIVtal-infected captive talapoin monkeys revealed a relative decrease in CD4(+) cell numbers in chronically (>2 years) infected animals. No other signs of immunodeficiency were observed in any of the infected animals. PCR amplification followed by DNA sequencing of two fragments of the polymerase gene revealed that SIVtal is different from the presently known lentiviruses and perhaps most related to the SIV from Sykes monkeys.

Animals↗
PubMed1994

Daudi supernatant, unlike other H-Y antigen sources, exerts a sex-reversing effect on embryonic chick gonad differentiation.

In vitro cultures of intact chick gonads (organ cultures) and reaggregation cultures of dispersed gonad cells (roller cultures) were made. Gonads or gonad cells from 7-day-old chick embryos, at the stage when sex-specific differentiation begins, were cultured in the presence of presumed H-Y antigen-containing supernatants, or co-cultured in the presence of H-Y antigen-producing cell lines. The H-Y antigen-producing cells tested were of human, mouse, bovine and chicken origin. During organ culture, addition of supernatant of the human lymphoma cell line Daudi, or co-culture with Daudi cells, stimulated a clear proliferation of the germinal epithelium in male gonads, indicating feminization. A similar effect was obtained by treatment with estradiol. In reaggregation culture, the increase in nuclear size of germ cells was chosen as a parameter for feminization. A significant increase of germ cell nuclear size was observed in gonads cultured in the presence of Daudi supernatant. In both organ cultures and reaggregation cultures, other tested H-Y antigen sources and semi-purified H-Y antigen fractions did not exert significant effects on differentiation of the gonads or on the average area of the germ cell nuclei. These findings suggest that it is not H-Y antigen, but another protein produced by Daudi cells, that might be responsible for the sex-reversing effects.

Animals↗
PubMed1992

[Veterinary education; is it balanced?].

As a professional body, we are continually torn between two alternatives: do we love animals or do we see them as bioindustrial objects, do economics prevail or do ethics, should we specialize or should we retain a broad basis of knowledge? I would like to go further and philosophize about a totally different sort of specialisation - veterinarians who are concerned solely with intensive animal husbandry and veterinarians who are concerned solely with the free-range sector. Could something such as moral specialisation exist?

Animal Husbandry↗
PubMed1991

Influence of claw clipping, stocking density and feeding space on the incidence of scabby hips in broilers.

1. The aetiology of scabby hips was studied in broilers by scratching the skin with chicken claws, clipping the birds' claws and varying the effects of stocking density and food trough allocation. 2. Gentle scratching twice a week resulted in skin lesions that could not be distinguished from clinical scabby hips at slaughter. Interaction between birds appeared to be a prerequisite for the skin condition to develop. 3. Clipping of the claws at day 25 could almost completely prevent scabby hips at day 45 when the birds were slaughtered. 4. No positive correlation was found between feather condition and the severity of scabby hips at slaughter at day 45. 5. Decrease in stocking density and an increase in feeding space resulted in a reduction of skin lesions at day 25 and resultant scabby hips after slaughter.

Animals↗
PubMed1991

Ascites in broilers. 1. Experimental factors evoking symptoms related to ascites.

Male broilers of two genetically related stocks with divergent growth rates and feed conversion ratios were used to study metabolic backgrounds on the occurrence of pulmonary hypertension, heart failure, hypoxemia, and ascites in poultry. An experiment with a 2 x 2 x 2 x 2 factorial split-plot arrangement of treatments with 96 groups of 12 broilers was performed. Effects of stock and environmental factors such as ambient temperature, dietary fat, and dietary energy on performance, energy metabolism, oxygen consumption, hematocrit values, and mortality were investigated in broilers from 1 to 5 wk of age. Dissimilar responses of the two stocks to environmental factors reflected genotype by environment interactions and revealed metabolic disorders related to heart failure and ascites. The results indicated that in the stock with the lower feed conversion ratio, a fast protein accretion was achieved together with a reduced ability to convert chemical energy to metabolic heat and to deposit body fat directly from ingested fat. Birds with a low feed conversion ratio show less flexibility in metabolic adaptation to a changing environment, which can account for the development of ascites.

Animal Feed↗
PubMed1990

A case of combined hermaphroditism and autofertilisation in a domestic rabbit.

A true hermaphrodite rabbit served several females and sired more than 250 young of both sexes. In the next breeding season the rabbit, which was housed in isolation, became pregnant and delivered seven healthy young of both sexes. It was kept in isolation and when autopsied was again pregnant and demonstrated two functional ovaries and two infertile testes. A chromosome preparation revealed a diploid number of autosomes and two sex chromosomes of uncertain configuration.

Animals↗
PubMed1989

[Veterinary care and concerns and intensive animal husbandry].

Developments in intensive animal husbandry as well as the reactions called forth by this new form of livestock husbandry in various groups of society and in research workers are reviewed in the introductory part; it was only during the past few years that veterinary medicine in the Netherlands began to concern itself with the negative effects of intensive animal husbandry on animal health and welfare. The practical situation in poultry and pig husbandry is then subjected to a critical analysis. It is concluded from a number of objective observations such as the use of pharmaceutical agents and vaccines and the appearance of particular pathological changes that limits should be imposed on growth. Reflection in veterinary medicine, resulting in the acceptance of health and welfare in animals and man, environment and economic values as equivalent factors, is advocated.

Animal Husbandry↗
PubMed1985

Endoscopy in birds.

Endoscopic examination is described as a valuable diagnostic method in birds. In the introduction, reference is made to the literature on this subject. Apart from the classical approaches, alternative sites to enter the thoraco-abdominal cavity in birds are discussed. The basic equipment for endoscopy in birds is described and a new biopsy forceps which makes a secondary puncture redundant is introduced. After a discussion of the indications and complications, the value of the endoscopic examination is compared with other diagnostic methods for the diagnosis of avian tuberculosis in birds.

Animals↗
PubMed1982

[Triploidy as a possible cause of intersexuality in chickens (Gallus domesticus)].

A number of cases of intersexuality occurred in a fairly large number of cases in 6-8 months-old laying hens on two poultry farms in the province of Limburg. When macroscopic and microscopic studies failed to supply any evidence concerning the cause of the considerable development of the right gonad, it was decided to do a chromosome analysis. Three intersexes in which the chromosomes were studied, were found to be triploid birds showing a ZZW sex chromosome combination, which aberration may have been the cause of the intersexuality observed.

Animals↗
PubMed1982

The prevention of orchiopexy-induced testicular lesions in the pig.

From previous experiments it was concluded that failure of spermatogenic cells to differentiate after orchiopexy seems to be due to surgical trauma. Furthermore it appeared that in normally descended testes of naturally unilaterally cryptorchid pigs subjected to orchiopexy, the spermatogenic epithelium was poorly developed as compared with that of scrotal testes of unilaterally cryptorchid pigs that had not undergone the surgical procedure. Even simple inguinal surgery in unilaterally naturally cryptorchid piglets may already give rise to severe histological lesions in the spermatogenic epithelium of the normally descended contralateral testes at adulthood. On the other hand extirpation of the retained testis by laparotomy does not affect the spermatogenic epithelium in the contralateral scrotal testis. From these experiments it may be concluded that with regard to the prevention of sterility in unilaterally cryptorchid pigs it may be preferable to extirpate the retained testis rather than to perform an orchiopexy.

Animals↗
PubMed1982

Spermatogenesis in the boar.

In order to study kinetics of the spermatogenic epithelium in the adult boar, a method has been developed to prepare seminiferous tubules mounted as a whole, after which these tubules have been processed and studied as described previously only for rats, mice and hamsters. The tubules were fixed in Zenker for 24 hours and stained with periodic acid - Schiff - haematoxylin to identify the steps in spermatid development, or by Harris' hemalum to identify spermatogonia and spermatogonial divisions. Spermatid development in the boar is comparable with spermatid development in small laboratory rodents. The spermatogenic cycle was divided into 12 steps, each characterized by one step in the development of the acrosome or the shape of the nucleus of the spermatids. By studying whole mounts we could distinguish four classes of spermatogonia in the boar: undifferentiated A spermatogonia (A s, A pr, A al), differentiating A spermatogonia (A1, A2, A3, A4), intermediate and B spermatogonia. The boar demonstrates a striking similarity with small laboratory rodents.

Animals↗
PubMed1981

The influence of elevated testicular temperature and scrotal surgery on the number of gonocytes in the newborn pig.

Morphological changes become apparent shortly after birth in the abdominally located testes of the pig. To test the influence of temperature on gonocyte multiplication, scrotal testes of newborn piglets were subjected to continuous artificial heating. It was found that in the young pig during the first 2 weeks of life when the mitotic activity of the gonocytes is high, they are very sensitive to a combination of elevated testicular temperature and scrotal surgery.

Animals↗
PubMed1979

Induction of spermatogenesis in the naturally cryptorchid pig.

Abdominal testes of adult, naturally unilaterally cryptorchid boars were subjected to continuous artificial cooling for 5, 15, 25, or 45 days. This treatment initiated development of the spermatogenic epithelium. After a cooling period of 45 days there was complete differentiation in many seminiferous tubules. The results indicate that the spermatogenic arrest in abdominally located testes is not due to an inborn defect in the testis, but is caused by the maintenance of the testis at the abdominal temperature.

Animals↗
PubMed1979

The origin of orchiopexy-induced testicular lesions in the pig.

Cooling experiments of abdominal testes in adult, naturally cryptorchid pigs indicate that spermatogenic arrest in abdominal testes is not due to an inborn defect, but is caused solely by maintenance of the testis at abdominal temperature. It is postulated that failure of spermatogenic cells to differentiate after orchiopexy results from surgical trauma. Evaluation of the orchiopexy procedure revealed that simple manipulation of a normally descended testis may give rise to damage to the spermatogenic epithelium. Furthermore, it appeared that, in normally descended testes of naturally unilaterally cryptorchid pigs subjected to orchiopexy, the spermatogenic epithelium was poorly developed as compared with that of scrotal testes of unilaterally cryptorchid pigs that had not undergone a surgical procedure.

Animals↗