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Biomedical subjects

H J Els

Publications and source records attributed to H J Els.

At least 19 recordsLinked to original sources
PubMed1999

Sperm abnormalities associated with high copper levels in impala (Aepyceros melampus) in the Kruger National Park, South Africa.

The morphology of spermatozoa may be affected by very low concentrations of pollutants in the environment, and sublethal effects of toxic substances can be detected by studying the sperm of an animal. Sperm were collected from 50 impala (Aepyceros melampus) from a conservation area in South Africa and studied ultramicroscopically. Thirty-two samples were obtained from animals close to a copper mine, while 18 represented animals from an unpolluted area and held in captivity. Liver samples from all these animals were analyzed for their copper content. The findings from 12 animals kept in captivity and fed on a diet to which copper was added correlated with the findings from the field study. The general condition of the animals as expressed by the fat content of the bone marrow from the area exposed to copper contamination was affected detrimentally in comparison to the animals from the uncontaminated area. High percentages of sperm with neck vacuoles were found in all animals with high liver copper levels. A statistically significant correlation is demonstrated between the percentage of impala sperm with vacuoles in the neck region and the copper concentrations in this group of animals.

Animals↗
PubMed1998

Viruses and virus-like particles identified in ostrich gut contents.

Samples of either gut content from ostriches showing symptoms of enteritis, or allantoic fluid of eggs inoculated with ostrich isolates, were examined for the presence of viral agents by direct negative-contrast electron microscopy. Only a few virus types could be identified with certainty, namely a circovirus (1 sample), a coronavirus (1 sample), a member of either the toga- or bunyaviridae (1 sample), enterovirus (16 samples) and paramyxovirus (26 samples). A large number of samples contained structures resembling myxovirus particles that were interpreted as fringed membranous particles of non-viral origin. An unusual observation of probable single-strand nucleocapsid helices, possibly originating from digested plant material and which were identified in a number of small intestine samples, is reported. This is the 1st report of a spectrum of viruses and virus-like particles occurring in enteric samples from ostriches in South Africa. The low incidence and variety of viruses reported here contribute to the multifactorial origin and complexity of enteric disease in ostriches as well as in other birds and mammalian species.

Animals↗
PubMed1994

Rotavirus in Saanen goats.

Rotavirus particles were detected in the stools of 8 out of 12 Saanen kids with either diarrhoea or an increased rectal temperature. No other pathogenic organisms could be recovered from these kids. This is believed to be the first report of rotavirus infection in goats in southern Africa.

Africa, Southern↗
PubMed1993

Besnoitiosis in a horse.

Besnoitiosis was confirmed in a pony which presented with inspiratory dyspnoea, scleroderma and ventral oedema. Numerous cysts were visible in the sclerae. Histological examination of the skin confirmed the presence of numerous cysts. The parasite could not be transmitted by subcutaneous injection of homogenised skin from the infected horse to rabbits and a horse. Ultrastructural morphology of the crescent-shaped bradyzoites was not compatable with Besnoitia besnoiti or B. jellisoni and it is proposed that the infection was caused by B. bennetti.

Animals↗
PubMed1992

Effects of gamma-linolenic acid on mitosis and nuclear morphology in osteogenic sarcoma cells.

In this study it is shown that gamma-linolenic acid (GLA) at concentrations of 10, 20 and 50 micrograms/ml has a dose-responsive inhibitory effect on mitosis in osteogenic sarcoma cells after exposure for 24, 48 and 72 hours, respectively. GLA also has marked effects on the morphology of the nucleus and nucleolus of these cells. Decreased silver staining of nuclear phosphoproteins was also evident in GLA-supplemented cells.

Antineoplastic Agents↗
PubMed1989

Characterization of the microbial community colonizing the anal and vulvar pores of helminths from the hindgut of zebras.

Scanning and transmission electron microscopy were used to examine the adherence and in situ morphology of the microbial community colonizing the anal and vulvar pores of the subfamily Cyathostominae (Nematoda: Strongylidae) from the colon of Burchell's zebra (Equus burchelli antiquorum). Two different morphological types of asporogenous rod were prominent in the microbial community. One was a thin, septate, filamentous organism (0.4 to 0.5 micron by 2 to 3 microns) with blunt ends, which was more prominent at the site of attachment. The other was a larger (1.8 to 2.4 microns by 5 to 10 microns) multicellular rod with round ends in the form of a trichome. Spiral- and vibrio-shaped bacteria were also present in the thin sections. The septate filaments were shown to contain a cell spacer similar to those described in Methanospirillum hungatei. Attachment to the cuticle was by means of an amorphous electron-dense material with fibrillar appearance and not by specialized holdfast segments. Ten isolates were obtained from a habitat-simulating medium on which a homogenate from the posterior region was plated. Antibodies were raised to whole cells of five rod-shaped isolates in rabbits and fluorescein isothiocyanate labeled. Positive bright-yellow fluorescence was obtained with one of the clostridial isolates. The results are discussed with reference to other bacteria with similar morphology, the nature of this unique interrelationship between the microbial community and its parasitic host inside the equine hindgut, and the possibility of biological control of parasitic helminths.

Animals↗
PubMed1989

The isolation and attenuation of a virus causing rhinotracheitis in turkeys in South Africa.

In March 1978, a number of turkeys with severe respiratory symptoms affecting over 80% of the flock were investigated for a possible causative agent. With the standard techniques used for the isolation of bacteriae, mycoplasmae and viruses, only Mycoplasma gallisepticum, Mycoplasma meleagridis and Newcastle disease virus were isolated. Tracheal organ cultures were subsequently prepared from 27-day-old turkey embryos and inoculated with sinus exudate from affected turkeys. After an incubation period of 4 days a virus was isolated with which the typical symptoms, as observed in the field, could be reproduced in susceptible turkeys after 3-5 days. Following primary isolation in tracheal organ cultures, the virus grew readily in embryonated eggs and Vero cells. With the electron microscope, virus-like particles, varying in size from 40 nm-500 nm, were observed, having a pleomorphic shape and studded with fine surface projections. The virus seems to fall into the family Paramyxoviridae. A vaccine produced from attenuated virus in embryonated eggs afforded good protection against mortalities due to airsacculitis that normally follows on to turkey rhinotracheitis infection. The serological and clinical effects of the virus on chickens are also reported on.

Animals↗
PubMed1988

A comparison of fixatives suitable for scanning electron microscopy of Habronema spp.

Members of the genus Habronema (Nematoda: Habronematidae) were preserved in 4 fixatives for examination with scanning electron microscopy (SEM). Tegumental features of the anterior and posterior extremities of these specimens were compared to evaluate the effect of the fixatives: modified Flemming's solution, glutaraldehyde (GA), Karnovsky's fixative and 70% ethanol. Fixatives were assessed on the appearance of the tegument, evidence of any wrinkling, shrinkage or swelling and the degree of extension in the male tail. Seventy per cent ethanol gave the most satisfactory results.

Animals↗
PubMed1987

Uncoating of parental bluetongue virus to core and subcore particles in infected L cells.

A study was made of the fate of parental bluetongue virus (BTV) in infected cells. Within the first hour after infection, the BTV particles are converted to core particles with the loss of major capsid polypeptides P2 and P5. The particles are able to synthesize mRNA in vitro in a transcription reaction characterized by a temperature-dependent inhibition at high core concentrations. From about 6 hr after infection a second uncoating event is observed in which the 470 S core particles are converted to 390 S subcore particles. These particles are morphologically strikingly different from core particles and have a skeletonlike structure with a hexagonal profile and a side to side diameter of 40 nm. These subcore particles contain only one major structural protein, P3, and three minor proteins, P1, P4, and P6. They do, however, contain all 10 double-stranded RNA segments. The results suggest that the characteristic capsomeres on the surface of core particles are composed mainly of P7, the soluble group-specific antigen of BTV. The subcore particles are stable only at very low salt concentrations. Under these conditions no transcriptase activity can be demonstrated.

Animals↗
PubMed1986

Scanning electron microscopy of Bunostomum phlebotomum (Railliet, 1900).

Live specimens of Bunostomum phlebotomum were collected from the small intestine of a calf and processed for scanning electron microscopy using standard methods. This paper describes the surface morphology of adult worms. All these hookworms showed a dorsally bent anterior end with its buccal capsule, which opens antero-dorsally with a pair of chitinous cutting plates on the ventral margin. Prominent cervical papillae and a well developed male bursa with a dorsal and 2 lateral lobes, were observed. The female tail is slender and pointed with the anal opening close to the tip. Further studies are necessary to demonstrate morphological differences from other hookworms and to obtain more detail of the male bursa and female tail.

Ancylostomatoidea↗
PubMed1983

Scanning electron microscopy of Strongylus spp. in zebra.

The external ultrastructure of the anterior and posterior extremities of the nematodes, Strongylus asini , Strongylus vulgaris, Strongylus equinus and Strongylus edentatus, was studied with scanning electron microscopy (SEM). Fresh specimens of S. asini were collected from the caecum, ventral colon and vena portae of Equus burchelli and Equus zebra hartmannae ; S. vulgaris from the caecum, colon and arteria ileocolica of E. burchelli ; S. equinus from the ventral colon of E. z. hartmannae and S. edentatus from the caecum and ventral colon of both zebras , during surveys of parasites in zebras in the Etosha Game Reserve, South West Africa/Namibia, and the Kruger National Park, Republic of South Africa. The worms were cleaned, fixed and mounted by standard methods and photographed in a JEOL JSM - 35C scanning electron microscope (SEM) operating at 12kV . The SEM showed the following differences: the tips of the external leaf-crowns varied and were fine and delicate in S. asini , coarse and broad in S. vulgaris and, in S. equinus and S. edentatus, closely adherent, separating into single elements for half their length. The excretory pores showed only slight variation, and the morphology of the copulatory bursae did not differ from those seen with light microscopy. The genital cones differed markedly: S. asini had a ventral triangular projection and laterally 2 finger-like projections: in S. vulgaris there were numerous bosses on the lateral and ventral aspects of the cone; in S. equinus 2 finger-like processes projected laterocaudally ; and in S. edentatus 2 pairs of papilla-like processes projected laterally on the ventral aspects, and a pair of rounded projections and a pair of hair-like structures adorned the dorsal aspects.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Studies on neonatal calf diarrhoea caused by rotavirus: transmission of the disease and attempted vaccination of colostrum-deprived calves.

Mild to severe scouring could be produced in colostrum-deprived calves with tissue culture-adapted rotavirus and feacal material from field cases of calf diarrhoea. The feaces of experimentally infected calves contained rotavirus for at least 3 days. Pathogenic bacteria were presented in one calf only and this calf also showed the most severe gastroenteritis. Eight calves were vaccinated with a live rotaviral calf diarrhoea vaccine and subsequently challenged with infective rotavirus. Mild scouring was observed after vaccination, but the calves remained normal after challenge. Rotavirus particles were detectable in the faeces for a few days after vaccination and challenge.

Animals↗
PubMed1979

The isolation and cultivation of calf rotavirus in the Republic of South Africa.

Calf rotavirus was cultivated and propagated in tissue culture from faeces of 3-week-old calves suffering from severe diarrhoea. Criteria for viral involvement were: production of cytopathic effect in primary foetal calf kidney cells, specific fluorescence, and identification of the agent by means of electron microscopy. In a limited serological survey the majority of the cows on an infested farm were found to possess neutralizing antibodies to the local rotavirus strain.

Animals↗