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Biomedical subjects

A Jespersen

Publications and source records attributed to A Jespersen.

At least 19 recordsLinked to original sources
PubMed2004

Morphology of the kidney in the West African caecilian, Geotrypetes seraphini (Amphibia, Gymnophiona, Caeciliidae).

This study deals with the morphology and ultrastructure of the mesonephros in adult caecilians of the species Geotrypetes seraphini. Based on serial sections in paraffin and araldite, nephrons are reconstructed and the cellular characteristics of different nephron segments described. The long and slender mesonephric kidneys of G. seraphini are broadest caudally and taper toward the front, where the organs are divided into smaller segmental divisions. Two nephron types can be distinguished on the basis of their connections to the coelom and their position within the nephric tissue: ventral nephrons connect to the coelom via a ciliated peritoneal funnel, whereas medial nephrons lack this connection. Both nephron types are composed of a filtration unit, the Malpighian corpuscle, and a renal tubule, which can be divided into six morphologically distinct segments: neck segment, proximal tubule, intermediate segment, early distal tubule, late distal tubule, and collecting tubule. Collecting tubules merge and form a branch system that opens into collecting ducts. Collecting ducts empty into the Wolffian duct. Proximal tubules of nephrons in the frontal divisions are morphologically different from the proximal tubules of more caudal kidney regions. Distal tubule subdivision is only clearly recognizable at the electron microscopic level. The length of each nephron segment is calculated from a ventral nephron with a total length of approximately 3.8 mm, and the course of the segments within the nephric tissue is reported. The number of nephrons was estimated at 1,700 units in each kidney. The segmentation and ultrastructure of the mesonephric nephrons in G. seraphini are discussed in relation to nephron descriptions from other caecilians and we further discuss the evolutionary origin of the amphibian nephron.

Africa, Western↗
PubMed2001

Expression of cystic fibrosis transmembrane conductance regulator in the skin of the toad, Bufo bufo and possible role for Cl- transport across the heterocellular epithelium.

Evidence is discussed that apical CFTR Cl- channels of mitochondria-rich (MR) cells of Bufo bufo skin conduct beta-adrenergic receptor-activated Cl- currents. Ussing chambers studies revealed the following selectivity sequence of the receptor activated conductance, Cl- > Br- > NO3- > I-. With ion selective microelectrode-techniques, it was shown that receptor-coupled Cl- channels are not located in principal cells. A small conductance (7-10 pS) CFTR-like Cl- channel is located in the apical plasma membrane of MR cells. Short life times of sealed patches prevented detailed study of its selectivity to other halide ions and its molecular regulation. With monoclonal hCFTR-antibodies, selective expression in MR cells of the targeted antigens could be demonstrated. A transcript of CFTR was amplified in the skin, and a bbCFTR cDNA clone was generated from toad skin mRNA that exhibits 89% amino acid identity with the human homologue. The frequency of obtaining channels in patch clamp studies was too low for accounting quantitatively for the macroscopic conductance. Since MR cells were isolated by trypsin, and a putative extracellular loop of the deduced bbCFTR protein contains a target peptide bond for trypsin, enzyme treatment may have destroyed apical CFTR molecules.

Amino Acid Sequence↗
PubMed2000

Morphology of the kidney in larvae of Bufo viridis (Amphibia, Anura, Bufonidae).

This study deals primarily with the morphology and ultrastructure of the pronephros in the green toad Bufo viridis during prometamorphosis when the pronephros and the developing mesonephros function simultaneously. Furthermore, the mesonephros was studied during pro- and postmetamorphosis with emphasis on the distal segments of the nephron. The paired kidneys consist of two cranial pronephroi immediately behind the gill region and two more caudal elongated mesonephroi. Each pronephros consists of a single convoluted tubule which opens into the coelom via three nephrostomes. This tubule is divided into three ciliated tubules, three proximal tubule branches, a common proximal tubule and a distal tubule, which in turn continues into the nephric duct. No intermediate segment is present. The length of the pronephric tubule is 12 mm, including the three branches of the ciliated tubules and proximal tubules. Primary urine is formed upon filtration from an external glomerulus, which is a convoluted capillary lined by podocytes, a specialization of the coelomic epithelium. From the coelom the filtrate is swept into the ciliated tubules. In the collecting duct system of the developing mesonephric nephron epithelial cells with conspicuous, apical osmiophilic granules appear in larvae of 9-10 mm. Heterocellularity of mixed intercalated (mitochondria rich) cells and principal cells is observed in the collecting duct system and nephric duct from a larval body length of 14 mm. As the proliferation of mitochondria-rich cells proceeds, the osmiophilic granules disappear and are completely absent from the adult amphibian mesonephros.

Animals↗
PubMed2000

Effects of nonylphenol and 17beta-estradiol on vitellogenin synthesis and testis morphology in male platyfish Xiphophorus maculatus.

Nonylphenol has been found to exert estrogenic effects in fish and may influence the fertility of male fish. In the present study, the effects of nonylphenol and 17beta-estradiol on vitellogenin synthesis and testis morphology in platyfish Xiphophorus maculatus were investigated. Vitellogenin was observed in the plasma of all fish exposed to nonylphenol or 17beta-estradiol. Exposure to 17beta-estradiol resulted in a significant reduction in the gonadosomatic index. A tendency for a dose-dependent reduction in the gonadosomatic index in the nonylphenol exposed groups was observed. Histological examination revealed dose-dependent effects of nonylphenol on the testis structure. The testes of control fish contained numerous cysts with spermatogenetic cells. The testes of fish exposed to nonylphenol or 17beta-estradiol showed a decrease in the number of cysts concomitant with an increase in the amount of hypertrophied Sertoli cells present. Formation of spermatozeugmata is compulsory for this species, but free spermatozoa were observed in the efferent ducts of the treated fish. The study indicates that nonylphenol has estrogenic potency, and that both nonylphenol and 17beta-estradiol have marked effects on the testis morphology of X. maculatus. The ambient concentration of nonylphenol was measured by high pressure liquid chromatography during the experiment. The measurements revealed that the actual concentrations of nonylphenol in the water were about 30-40 % of the nominal concentrations.

Animals↗
PubMed1998

Effects of nonylphenol and 17 beta-oestradiol on vitellogenin synthesis, testicular structure and cytology in male eelpout Zoarces viviparus.

Nonylphenol has been found to be oestrogenic in fish and may influence the reproductive system of male fish. In the present study, the effects of low (10 microg g-1 week-1) and high (100 microg g-1 week-1) doses of nonylphenol and of 17 beta-oestradiol on the synthesis of vitellogenin and on testicular structure and cytology were investigated in male eelpout Zoarces viviparus during active spermatogenesis (May) and late spermatogenesis (June). Twenty-five days after injection, a significant dose-dependent increase in the plasma vitellogenin concentration, measured by enzyme-linked immunosorbent assay, was observed in the treated groups. A highly significant reduction in the gonadosomatic index was observed concomitant with the increase in the plasma vitellogenin concentration. Macroscopically, milt was observed to be present in the control fish, but was sparse or absent in the treated fish. Histological examination using light microscopy revealed severe effects of nonylphenol as well as of oestradiol treatment on testicular structure. Control fish had seminiferous lobules containing spermatogenic cysts and only a few spermatozoa (May) or had the walls of their seminiferous lobules lined with cuboidal Sertoli cells (June). In the treated fish, the seminiferous lobules were degenerated (May) or were filled with numerous spermatozoa and the Sertoli cells appeared very squamous (June). Electron microscopy revealed greater numbers of phagocytosed spermatozoa in these Sertoli cells. In rats, -glutamyl transpeptidase (-GTP) has been used as a specific marker of Sertoli cell function. In the present study, both nonylphenol and 17 beta-oestradiol treatment resulted in a reduction in the activity of this enzyme. The study provides evidence that nonylphenol is oestrogenic, as indicated by the large increase in vitellogenin synthesis, and that both nonylphenol and oestradiol have marked effects on the testicular structure and cytology of germ cells and Sertoli cells of male Z. viviparus.

Animals↗
PubMed1978

Metastatic osteomyelitis following BCG vaccination.

An 8-year-old girl, who had been vaccinated with BCG without subsequent regional reactions, developed osteomyelitis in the left calcaneus 7 months later. The process healed after surgical treatment and chemotherapy for 1 year. Culture from the bone abscess gave growth of mycobacteria which could not be distinguished from BCG.

Abscess↗
PubMed1977

Infection of Clethrionomys G. glareolus Schreb. (red mice) with Mycobacterium tuberculosis and Mycobacterium bovis injected subcutaneously.

Groups of red mice were injected with doses from 10 mg to 10(-8) mg semidried culture of a strain of M. tuberculosis and with doses from 10(-1) to 10(-8) mg of a strain of M. bovis. Some animals were killed about 1 1/2 and 3 months after injection and the remainder lived until death occurred spontaneously. The number of tubercle bacilli in the organs was evaluated by microscopy of smears, in some cases by quantitative culture. Among the mice injected with M. tuberculosis in doses of up to about 2 million viable units, not one case of death occurred which could be attributed to tuberculosis. The autopsy findings consisted exclusively of lesions at the site of injection and in the regional lymph glands. Quantitative culture showed growth of a few viable units in the lymph glands, spleen or lungs, but no sign of progressive infection. Out of 10 mice injected with a giant dose of 3 X 10(7) viable units, only two died of tuberculosis. M. bovis provoked fatal tuberculosis in all animals injected with doses from 6.9 million to 7 viable units. Severe caseous lesions developed at the site of injection, in the lymph glands, in the lung, and often also in liver and spleen. The number of bacteria in the organs was enormous, particulary in the spontaneously dead animals. The survival times, which were dependent on dosage, varied from 51 to 159 days.

Animals↗
PubMed1976

Multiplication of Mycobacterium tuberculosis and Mycobacterium bovis in Microtus agrestis (field vole).

The multiplication of bacteria is examined by quantitative culture from the organs of two groups of field voles injected intraperitoneally with a large dose of M. tuberculosis or a small dose of M. bovis and killed at intervals during a period of up to 3 months after the injection. M. tuberculosis given in a dose of 7 X 10(5) viable units did not multiply, or multiplied only to a small extent. None of the animals in the group died from tuberculosis and the macroscopical lesions found at autopsy were insignificant. In contrast, a dose of 14 viable units of M. bovis provoked generalized tuberculosis running a rapid, fatal course. The bacteria multiplied almost uninhibited throughout the course of the infection.

Animals↗
PubMed1976

Acquired resistance of BCG-vaccinated red mice to infection with Listeria monocytogenes.

Infection experiments have shown that red mice, belonging to the vole family, could be infected with Listeria monocytogenes and that they were almost as susceptible to intravenous infection as Cf1 mice. Vaccination of red mice with BCG induced a resistance which could be demonstrated by prologation of the survival time of the animals after challenge with Listeria. The resistance was greatest in the second and third week after vaccination and was considerably higher after intravenous injection of BCG vaccine than after intraperitoneal or subcutaneous injection. On the basis of studies concerning the dose of vaccine, the route of vaccination, and the interval between vaccination and challenge, a method by which to evaluate the potency of a strain of BCG has been elaborated. By this method it was found that there was a significant difference between the resistance produced by a strain of BCG which is weakly virulent and one which is strongly virulent for hamsters.

Animals↗
PubMed1976

Tuberculin shock in red mice and CF1 mice immunized with strains of BCG or Mycobacterium tuberculosis.

Groups of red mice and CF1 mice immunized intravenously with varying doses of a weak and a strong strain of BCG and a strain of M. tuberculosis were challenged 3-4 weeks later with 2 or 0.5 mg of purified tuberculin injected intravenously. The shock sensitivity of the animals in the individual groups was evaluated on the basis of the number of deaths and the survival times after challenge. In the red mice, the strain of M. tuberculosis induced a significantly greater sensitivity than the BCG strains. The strong strain of BCG induced a slightly greater sensitivity than the weak strain, but the difference was not significant. The CF1 mice were more sensitive to tuberculin shock than the red mice, but any difference in the sensitivity of the animals in the individual groups immunized with the three strains could not be demonstrated.

Animals↗
PubMed1976

Acquired resistance against Listeria monocytogenes in red mice and CF1 mice immunized with strains of BCG or Mycobacterium tuberculosis.

Groups of red mice and CF1 mice immunized intravenously with varying doses of a weak or a strong strain of BCG or a strain of Mycobacterium tuberculosis were challenged 3 weeks after immunization with 0.1 or 0.2 ml 10(-2) Listeria monocytogenes injected intravenously, simultaneously with a non-immunized control group. The acquired resistance was determined on the basis of the number of survivors and the survival times of the animals that died spontaneously. In the red mice, the strong BCG strain induced a definitely higher resistance than the weak strain, and the M. tuberculosis strain a slightly higher resistance than the BCG strains. As in red mice, the resistance of CF1 mice was higher in animals immunized with M. tuberculosis than in those immunized with the BCG strains. However, the difference in the survival times of mice immunized with the two strains of BCG was much less than in red mice, and was only clearly significant as regards one of the doses used. The relationship between the virulence of a mycobacterial strain and its ability to induce acquired resistance against an infection with listeria or against an infection with virulent tubercle bacilli is discussed. It is concluded that red mice are more suitable than CF1 mice for evaluation of the protective potency of a BCG strain.

Animals↗
PubMed1976

Potency of purified tuberculin determined by the shock method on hamsters.

Two lots of purified protein derivative of tuberculin with different potencies determined by skin tests on guinea pigs, were examined for their capacity to induce shock in hamsters sensitized with BCG. Groups of hamsters were injected with varying doses of a highly potent strain of BCG grown in Dubos fluid medium. 4-5 weeks later two groups of animals sensitized with corresponding doses were injected intraperitoneally with 1 mg of each lot of tuberculin. 12 of the 20 hamsters given the strong tuberculin died, while all those given the weak tuberculin survived. An attempt was made to evaluate the mutual potency of the two lots of tuberculin by injecting groups of sensitized animals with 1 mg strong or 4 mg weak tuberculin. The difference in the number of deaths from shock in the two groups was not significant.

Animals↗
PubMed1975

Infection of Microtus arvalis (common vole) with Mycobacterium tuberculosis and Mycobacterium bovis.

The aim of the study has been to ascertain whether Microtus arvalis (common vole) is strongly susceptible to M. bovis but resistant to M. tuberculosis, as is the case with other members of the vole family, or whether it is susceptible to both species as demonstrated by Robert Koch. Groups of common voles have been injected subcutaneously or intraperitoneally with varying doses of finely dispersed suspensions of a virulent strain of M. bovis or M. tuberculosis. M. bovis multiplies strongly in the vole organism and a dose as small as 8 viable units provokes a progressive infection with rapid fatal outcome. Autopsy shows considerable processes at the site of injection and in the lymph glands. Tubercles are observed quite frequently in the lungs, bur seldom in the liver, spleen and kidneys. The organs contain a large number of tubercle bacilli, the caseous lymph glands enormous numbers. In contrast, the virulence of M. tuberculosis is low. None of the doses used, the highest being 6 x 10(6) viable units, provokes progressive infection in the animals injected subcutaneously and only in a few of those injected intraperitoneally. The macroscopical findings are inconsiderable, and it is characteristic of the M. tuberculosis infection that the lymph glands are seldom enlarged and have become caseous in exceptional cases only. The number of bacteria in the organs is small, except in the few animals in which the infection becomes progressive. The conclusion drawn from the experiment is that Microtus arvalis is susceptible to M. bovis but strongly resistant to M. tuberculosis, and in this respect resembles other members of the vole family examined hitherto.

Animals↗
PubMed1975

Bacteraemia in red mice (Clethrionomys g. glareolus Schreb.) after intraperitoneal injection of large doses of tubercle bacilli.

Römer (1903) has demonstrated that white mice injected intraperitoneally with large doses of tubercle bacilli isolated from man survived longer than mice injected with tubercle bacilli isolated from cattle. The blood of the spontaneously dead animals contained large numbers of tubercle bacilli. In the present study, red mice are injected intraperitoneally with 10 mg doses of different species of mycobacteria, and the number of bacilli in the blood is estimated at various intervals within the first 24 hours after the inoculation. The number of bacteria is considerably higher in the blood of mice injected with M. bovis, but, in contrast to M. bovis, M. avium disappears rapidly from the blood stream. Supplementary experiments show that red mice injected with M. bovis have a shorter survival time than mice injected with M. tuberculosis, and that the bacteraemia induced by M. bovis into white mice is clearly less pronounced than in red mice.

Animals↗