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Biomedical subjects

H Walt

Publications and source records attributed to H Walt.

At least 55 records · Page 3Linked to original sources
PubMed1990

Innervation and maturation of muscular tissue in testicular teratomas in strain 129/Sv-ter mice.

In strain 129/Sv-ter mice, teratomas develop spontaneously during the 13th day of gestation. These testicular germ cell tumors exhibit characteristics of different germ layers closely resembling normal embryonic tissue. We investigated the interrelationship between nervous and muscular tissues (often found side by side) in teratomas of 4-week-old 129/Sv-ter mice. In well-differentiated mouse teratomas, histochemically and immunohistochemically distinct muscle fiber types could be distinguished, but not with all reactions. According to its aerobic oxidative capacity, teratoma muscle tissue was comparable with normal muscles. However, with respect to myosin-related properties, fiber type differentiation was incomplete. The muscle fibers - generally arranged in bundles - contained one centrally located endplate which was contacted mostly by a single nerve terminal. From this, proper endplate zones within the fiber bundles were formed. Occasionally "type grouping" was encountered, suggesting collateral axonal branching paralleled by synapse elimination. Together with the earlier in vivo observation of muscular contractions, we assume that teratoma muscle fibers are innervated by nerve cells (within the nervous tissue compartments) corresponding to spinal motoneurons. Thus, myogenesis, maturation and innervation of skeletal muscular tissue in mouse teratomas are largely comparable to normal development.

Animals↗
PubMed1990

Abnormal chromosomal arrangements in human oocytes.

Ninety-one human oocytes, lacking signs of fertilization 50 h after insemination in vitro, were investigated cytogenetically to assess the frequency and type of chromosomal abnormalities. Chromosome spreading permitted adequate karyotyping in 55 oocytes. Non-determined numerical aberrations occurred with the following frequencies: hypohaploidy, 10.9% (6/55), hyperhaploidy, 14.5% (8/55) and hyperdiploidy, 3.6% (2/55). Total aneuploidy occurred with a frequency of 29.1% and was observed in oocytes from 30 patients. No correlation was found between specific chromosomal aberrations and type of infertility, stimulation treatment or gonadotrophin levels. On the other hand, the frequency of aneuploidy was significantly higher (P less than 0.05) in patients greater than 35 years of age. Two chromosomal complements (3.6%) had structural rearrangements; one oocyte had both structural and numerical chromosomal abnormalities and the other had differently condensed regions on the long arms of three chromosomes from group C. The overall frequency of chromosomal aberrations was 32.7%. Only two samples contained an additional set of polar body chromosomes. Thirteen oocytes presented sperm chromosomes in an arrested stage of premature chromosome condensation of the G1 phase and four oocytes showed asynchronous condensation of pronuclear chromosomes. Finally, it was concluded that the high proportion of chromosomal aberrations observed in human oocytes may contribute significantly to abnormal embryonic development in vitro.

Adult↗
PubMed1989

Alkaline phosphatase isozymes in human testicular germ cell tumors, their precancerous stage, and three related cell lines.

The four known isozymes of the human alkaline phosphatase (ALP) were detected by isoelectric focusing in extracts of various types of germ cell tumors, three related cell lines, and their precancerous elements (atypical germ cells). In seminoma, placental alkaline phosphatase (PLAP) and germ cell alkaline phosphatase (PLAP-like) could be separated by isoelectric focusing following isolation by immunoaffinity. The occurrence of both isozymes in seminoma could explain partial heat sensitivity and variation in electrophoretic patterns of the seminoma isozyme frequently observed upon starch gels, in comparison to the normal placental phenotype. The four ALP isozymes are produced not only in germ cell tumors, but already in precancerous tissues. Quantitative analysis showed that the amount of the four isozymes varies in parallel in the tumors tested. Maximal expression was found in seminoma. The relation between ALP gene overexpression and gene amplification by polyploidy of chromosomes 1 and 2 in these lesions is discussed. On the other hand, the ectopic expression of intestinal alkaline phosphatase and PLAP associated with overexpression of PLAP-like in tumor cells as well as in their precancerous stage indicates gene activation by some unknown mechanisms, probably a regulatory process affecting the three tissue-specific ALP genes simultaneously.

Alkaline Phosphatase↗
PubMed1989

Interphase cytogenetics in paraffin embedded sections from human testicular germ cell tumor xenografts and in corresponding cultured cells.

A protocol was developed that allows determination of chromosome aberrations in interphase nuclei from paraffin embedded human tissues. As a model system tissue sections from xenografts derived from three testicular germ cell tumors (two teratocarcinoma and one embryonal carcinoma), as well as sections from normal intestine and testicular tissues, were hybridized with a biotin-labeled DNA probe specific for 1q12. For comparison, isolated nuclei in suspension and metaphase spreads from in vitro cell lines derived from the respective xenografts were assayed. Our results show that interphase tumor cells with aberrant numbers of chromosome 1 can be reliably detected both in vitro and in vivo. Subclones with two and three labeled chromosomes, respectively, could be defined and quantitatively evaluated. Present and future possibilities to pinpoint specific chromosome aberrations directly in cells present in body fluids or in tumor tissues are discussed.

Animals↗
PubMed1989

Supernumerary chromosome 1 in interphase nuclei of atypical germ cells in paraffin-embedded human seminiferous tubules.

The so-called atypical germ cells or cells of carcinoma in situ morphologically resemble neoplastic cells in seminoma. Since seminomas show numerical aberrations of chromosome 1 we have used a DNA probe specific for chromosome region 1q12 to determine whether such aberrations can be detected in atypical germ cell nuclei in paraffin-embedded seminiferous tubules as well. One-third of intratubular nuclei, containing atypical germ cells, consistently showed three hybridization signals in contrast to two signals regularly observed in normal intestine and in spermatogonia. We thus show that cytogenetic studies of precancerous cells can be performed directly on the tissue where these cells originate.

Chromosome Aberrations↗
PubMed1988

Differences between subcutaneous and intraperitoneal forms of three human testicular teratocarcinomas in nude mice.

Three human testicular teratocarcinomas were serially passaged following subcutaneous transplantation into nude mice. Tumor cell suspensions from selected passages were injected intraperitoneally. The subcutaneous transplants of each tumor conserved the morphological characteristics of one component of the primary tumor, namely an embryonal carcinoma in one case and a yolk sac tumor in two. The latter maintained the capacity to synthesize alpha-fetoprotein (AFP). After intraperitoneal injection of cell suspensions, tumors, either attached to or even invading abdominal organs or in the form of free-floating tumor spheroids, were observed. AFP could be localized within the attached growths but not in the spheroids. A critical tumor volume and/or vascularization seemed to be necessary for AFP production in tumor cells. In spheroids from one tumor, cytogenetic analysis revealed both human and murine cells. Thus, these spheroids, apparently composed of tumor cells in the center and murine cells at the periphery, can not be considered to be embryoid bodies.

Animals↗
PubMed1988

[Are cephalosporins more active than penicillin G in poisoning with the deadly Amanita?].

High dose penicillin-G has been found empirically to be effective against liver cell damage in amanita mushroom poisoning. We have recently found that betalactam antibiotics inhibit eukaryotic DNA polymerase-alpha, penicillins being more active than cephalosporins, and this may explain the antagonistic effect of penicillin-G against amanitin toxicity. Preliminary experiments in liver cell cultures and in mice are summarized, as well as first clinical experience pointing to the possibility that cephalosporins may be more effective against amanita mushroom toxicity than penicillin-G.

Animals↗
PubMed1988

Structure and motility of primary cilia in the follicular epithelium of the human thyroid.

In order to clarify contradictory reports concerning ciliary structure and function, follicular epithelium from macroscopically normal portions of 37 surgical specimens of human thyroid were processed for video-microscopy and/or transmission electron microscopy. The cilia of living cells were immotile. In transverse sections the cilia revealed a 9 + 0 pattern at the base of the shaft, whereas towards the distal end the number of microtubular doublets diminished. Dynein arms, radial spokes and central microtubules were absent. The immotility and structure of these primary cilia implies that their function is not related to motility. The phylogenetic and ontogenetic development of the thyroid suggests that tumor cells of follicular origin displaying abnormal secondary cilia may represent a pathological variant of differentiation.

Adenocarcinoma↗
PubMed1988

Effects of tracheostomy on human tracheobronchial mucosa: a scanning electron microscopic study.

The protective functions missing in the upper airways of tracheostomy patients lead to functional and morphological changes in the lower respiratory tract. To obtain detailed data from the surface of the tracheobronchial mucosa, a scanning electron microscopic study was performed. Mucosal biopsies were taken from different sites of the tracheobronchial tree in 5 healthy control subjects, 5 patients with tracheostomy after laryngectomy, and 5 tracheostomy patients not affected by a history of smoking. Following scanning electron microscopic examination, the specimens were evaluated morphometrically. The percentage ciliary border and the individual mucosal surface changes depended on the biopsy site and the degree of previous damage. Individual structural alterations consisted of squamous metaplasia, giant cilia, compound cilia, and microplicae. Giant cilia represented an impressive form of differentiation in chronic bronchitis recognizable by scanning electron microscopy.

Bronchi↗
PubMed1988

[Condition of the tracheobronchial mucous membrane in patients with long-term tracheostomy. A scanning electron microscopy study].

In patients with tracheostomy and lacking or non-patent larynx the nose has no longer any climatic function for the lower airways. The comparison of mucosal alterations in the tracheobronchial tree of 5 laryngectomized patients, 5 tracheostomized patients without chronic bronchitis prior to the operation, and 5 otherwise healthy persons, who served as a control group, allows conclusions on the protective function of the intact upper airways. The specimens obtained from the right upper lobe bronchus, the main carina, the middle third of the trachea and below the stoma are examined by means of a scanning electron microscope (SEM). The percentage of the ciliated components of the epithelium is evaluated with a semi-automatically functioning image analyser. In healthy subjects the ciliated cells are clearly reduced close to the main carina. After laryngectomy a reduction of cilia along the entire tracheobronchial tree is observed, whereas at the main carina they are more or less lacking. In patients without preexisting chronic bronchitis the ciliary carpet is also almost totally absent near the carina and the stoma, while it is qualitatively better in the right upper lobe bronchus and the middle trachea. The method presented here, with evaluation of the distribution and ciliary surface morphology, allows quantification of the tracheobronchial mucosal condition under various anatomical and clinical circumstances. If the protective function of the upper airways is missing, the alterations of the tracheobronchial mucosa depend on the extent of the preexisting damage and on the level where the specimen is taken.

Adolescent↗
PubMed1987

Cytogenetic studies of human testicular germ cell tumours.

In a search for consistent cytogenetic alterations in testicular germ cell cancers we have thus far studied some twenty surgical specimens of seminomas and nonseminomatous tumours. From the literature and our results it is now clear that such testicular tumours generally have a hyperdiploid to hypotriploid chromosomal content, and frequently possess a possibly site-specific chromosomal marker, an isochromosome 12p. A significant correlation between the presence of the i(12p) and advanced clinical stages has been revealed in our study. Several other chromosomal regions are consistently involved in cytogenetic changes: 1p and 1q, 6q, 7p, 9q, 12p, 17q, and 22q. Although there is little doubt that characteristic chromosomal lesions exist in testicular germ cell tumours, the impact which specific lesions may have on tumour progression is still unclear.

Chromosome Aberrations↗
PubMed1986

A human testicular germ cell tumor with borderline histology between seminoma and embryonal carcinoma secreted beta-human chorionic gonadotropin and alpha-fetoprotein only as a xenograft.

Two macroscopically distinguishable components (designated soft and firm) of a human testicular germ cell tumor with borderline histology between seminoma, embryonal carcinoma and yolk sac tumor, were maintained as xenografts in nude mice for over 20 passages. Levels of beta-human chorionic gonadotropin (beta-HCG) and of alpha-fetoprotein (AFP) were normal in the patient's serum and were undetectable by immunohistochemical studies of the surgical specimen. The xenografted soft part, however, with morphologic characteristics of an embryonal carcinoma, secreted beta-HCG and AFP during early passages. The firm variant, histologically resembling a seminoma, did not produce these markers. Chromosomal and flow cytophotometric analyses showed genetic differences between the clonally stable variants. A common origin, however, is indicated by two similar marker chromosomes present in both variants.

Animals↗
PubMed1986

Ectopic nucleolus organizer regions (NORs) in human testicular tumors.

Investigation of nucleolus organizer regions (NORs) in hematopoietic malignancies has indicated that the distribution and rearrangement of these regions may be more important in malignant tissues than is their number. In one of the few studies thus far reported on NORs in human solid tumors, we describe here Ag-NORs in a group of human testicular germ-cell tumors and the corresponding patients. Four of seven malignancies demonstrated consistent ectopic NORs; explanations could include chromosomal rearrangement (insertion?) or derepression of preexisting inactive NORs.

Animals↗
PubMed1984

[Sperm flagella and cilia with pathologic motility and ultrastructure].

Motility of sperm flagella as well as of cilia is mechanically based on the principle of 9 + 2-tubules. It functions essentially by coordinated action between microtubules and the adenosine-triphosphatase dynein and was already present at the beginning of the evolution of the eucaryotes. Experimentally induced mutations in algae have resulted in numerous variations of the flagellar 9 + 2-structure. A mutation of this kind is also found in man, as immotile cilia syndrome (ICS) where anomalies in spermatozoa and in cilia (e.g. of the respiratory tract) are observed. Clinical manifestations of the syndrome have long been known (chronic bronchitis, bronchiectasis, sinusitis and male sterility). In addition, half of the patients exhibit situs inversus viscerum, known as Kartagener's syndrome, a subgroup of ICS. Electron microscopy was used to investigate sperm flagella with reduced motility from 9 patients (one with ICS) with primary infertility. Cilia of the respiratory tract from 7 patients (several with ICS) with chronic bronchial problems were analyzed for motility (using video techniques) and ultrastructure. Reduced motility or immotility of spermatozoa and immotile or dyskinetic cilia were always accompanied by ultrastructural anomalies. In spermatozoa, lack of dynein arms, 9 + 0-configuration and extratubuli were most frequently observed. The fibrous sheath was always asymmetrical. Structural ciliary defects resulted in non-parallel arrangements, electron dense matrix substance, extratubuli and lack of radial spokes. In one case, ciliary microtubuli were found in microvilli. In two patients, cilia as well as spermatozoa were analyzed. In the first, immotile spermatozoa without dynein arms and structurally normal cilia were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Actin and RNA are components of the chromatoid bodies in spermatids of the rat.

Chromatoid bodies present in spermatocytes and spermatids of the rat show directed movements around spermatid nuclei during differentiation. This transient organelle contains RNA and establishes contact to intranuclear material and to the acrosomal complex. In order to determine possible components of motility and to verify the presence of RNA, we used a recently developed low-temperature embedding resin combined with protein A-gold and enzyme-gold techniques for studies at the ultrastructural level. All chromatoid bodies analyzed display high concentrations of gold particles over the electron-dense regions when labeled with antiactin. In contrast, RNase-gold particles were localized mainly in the electron-translucent areas. Corresponding controls were always negative. The results suggest a relationship between the impressive motility of the chromatoid body and actin present in the organelle. In addition, specific localization of RNA supports earlier findings that consider the chromatoid body an essential element for differentiation during spermiogenesis.

Actins↗
PubMed1984

Differentiation of human testicular embryonal carcinoma and teratocarcinoma grown in nude mice and soft-agar cultures.

The differentiation pattern of two human germ cell tumors, grown in nude mice and in vitro is described. Tumor A was an embryonal carcinoma (EC) of borderline histology with characteristics of yolk sac tumor and of seminoma; tumor B was a teratocarcinoma with yolk sac elements and syncytiotrophoblastic giant cells. The morphology of an EC as well as cytogenetic characteristics were maintained during 20 passages in nude mice from tumor A and over 11 passages from tumor B. Tumor A did not grow in vitro. Cell suspensions prepared from xenografted tumor B grew into cystic embryoid bodies in semi-solid tissue culture medium. These embryoid bodies showed cuboidal and flattened cells with microvilli, junctional complexes, peripheral microfilaments, and annulated lamellae, reminiscent of the 'inner cell mass' of a blastula and of endoderm, respectively. When such colonies were transplanted into nude mice, however, only tumors with the morphology found in the transplants appeared.

Agar↗
PubMed1983

The use of Percoll gradients for the preparation of subpopulations of human spermatozoa.

Centrifugation of human spermatozoa on BWW- or HEPES-Krebs-Ringer-buffered media containing Percoll as a method to prepare pure gamete populations or subpopulations has been studied in detail. Application of this technique (Gorus & Pipeleers 1981) allowed us to obtain uncontaminated, motile spermatozoa and, after a subsequent Percoll gradient step, resulted in the enrichment of motile cells able to readily penetrate in vitro into AB-serum filled capillaries. The gradient sedimentation patterns of 25 different sperm samples with normal seminal parameters were found to be strongly influenced by the characteristics of the sample itself and also by the buffer used for filtration. However, the present study also revealed that ultrastructural changes and the release of intraspermatozoal enzymes were induced by the procedure. It is concluded that, although of interest clinically, the Percoll filtration technique in its present form is probably of limited value for cell biological and/or ultrastructural studies.

Cell Separation↗