Multiple forms of glycoproteins in the secretory product of the bovine subcommissural organ--an ancient glial structure

The glial subcommissural organ (SCO) is a conserved structure of the vertebrate brain that secretes a glycoprotein-rich product into both the extracellular matrix and the cerebrospinal fluid of the third ventricle that forms Reissner's fibre (RF). In order to identify specific secretory proteins of the subcommissural organ, a panel of antigen- and epitope-specific monoclonal antibodies was raised against bovine RF to study the distribution of epitopes in Western blots of bovine RF. Six groups of epitopes that were specific for SCO secretion were distinguished on the basis of their phylogenetic conservation and their different grades of resistance against chemical denaturation. The monoclonal antibody aRFME 4 recognised a carbohydrate-containing epitope that was strongly conserved in vertebrates and unique for SCO secretion. All epitopes showed essentially the same distribution pattern over 15 bovine RF glycoprotein fractions of different molecular masses in immunoblots indicating that the different RF fractions are closely related. They may represent multiple forms of SCO spondin.     

Age-related changes in peripheral nerves

Semi-thin sections of the sural nerve from 200 autopsy specimens taken from individuals of both sexes, ages 10 to 91 were morphologically examined. Thickness of the endoneurial capillary walls, and of the perineurium, number of endoneurial capillaries, myelinated fiber density and distribution of myelinated fibers were determined. An additional ultrastructural examination of selected nerves with characteristic values was performed. The analysis revealed a statistically significant age dependence for the investigated features. Increasing age was associated with decreased myelinated fiber density and decreased number of endoneurial capillaries. There was an age dependent increase in the thickness of capillary walls and the perineurium as well as increasing loss of large myelinated fibers. The findings were discussed and compared with similar results from the literature. Age related changes in peripheral nerves have to be interpreted as the result of the cumulative, life-long effect of various pathogenic factors, modified by genetic determinants and by a gradual decrease in regenerative capacity.     

Test-ordering by multiple physicians increases unnecessary laboratory examinations

In modern teaching hospitals, patients typically receive direct care from a succession of different physicians, each of whom may order diagnostic tests on the same patient. We examined the association of test-ordering by multiple physicians with unnecessary duplication of 20-test chemistry profiles in 198 consecutively admitted patients. In a multivariate regression model, the number of duplicate chemistry profiles ordered for a patient was significantly correlated with the number of physicians ordering profiles after controlling for the overall intensity of profile testing. In a case-control analysis comparing duplicate with nonduplicate profiles, redundant tests were significantly more likely to have been ordered by a new physician who had not ordered a patient's previous profile than by the same physician who had ordered the previous chemistry panel. We conclude that test ordering by multiple physicians, the prevalent pattern in almost all teaching hospitals, predisposes to unnecessary laboratory examinations.     

Importance of immunohistochemistry for neuro-oncology. IV. Distribution model of beta human chorionic gonadotropins in intracranial germ cell tumors

beta-Human choriogonadotropic hormone (beta-HCG) is considered a good marker for trophoblastic differentiation of germ cell tumors. 34 primary intracranial germ cell tumors (15 germinomas, 6 mature teratomas, 1 embryonal carcinoma, 2 endodermal sinus tumors and 10 mixed germ cell tumors) were immunohistochemically evaluated for the presence of beta-HCG positive cells. In 8 of 15 germinomas and 6 of 10 mixed germ cell tumors beta-HCG cells were demonstrable. In the germinomas such cells included both syncytiotrophoblastic and mononuclear cells which histologically did not correspond to the cytotrophoblast. In one case the patient had exhibited a precocious puberty. Of the 6 beta-HCG positive mixed germ cell tumors, two contained elements of choriocarcinoma. In the cytotrophoblasts of the choriocarcinoma regions, beta-HCG was only sparsely demonstrable. Both of these patients had manifest precocious puberty clinically. The advantage of immunohistochemical demonstration of the beta-HCG compared to conventional histology is in the definite identification of trophoblastic differentiation, in particular the exact recognition of the choriocarcinoma segments, which can be critical for the prognosis. Demonstration of isolated syncytiotrophoblasts and beta-HCG positive mononuclear cells in the seminomas is of no prognostic significance and is primarily of theoretical interest.     

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Identical mutations in the CSB gene associated with either Cockayne syndrome or the DeSanctis-cacchione variant of xeroderma pigmentosum

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are two hereditary disorders in which photosensitivity is associated with distinct clinical and cellular phenotypes and results from genetically different defects. We have identified the primary molecular alteration in two patients in whom clinical manifestations strongly reminiscent of a severe form of XP were unexpectedly associated with the CS cellular phenotype and with a defect in the CSB gene. Sequencing of the CSB -coding region in both cDNA and genomic DNA showed that these patients had identical alterations to those in a patient with the clinical features of the classical form of CS. These data, together with fluorescence in situ hybridization analysis, demonstrated that the two siblings with XP as well as the CS patient were homozygous for the same CSB mutated allele, containing a silent C2830T change and a nonsense mutation C2282T converting Arg735 to a stop codon. The finding that the same inactivating mutation underlies different pathological phenotypes indicates that there is no simple correlation between the molecular defect and the clinical features. Therefore, alterations in the CSB gene give rise to the same repair defect at the cellular level but other genetic and/or environmental factors determine the pathological phenotype.     

In vitro study on the impact of fish sera on the survival and fine structure of the eel-pathogenic acanthocephalanParatenuisentis ambiguus

The effects of fish sera on the growth and fine structure of infective larvae of the eel-pathogenic acanthocephalanParatenuisentis ambiguus (Eoacanthocephala: Tenuisentidae) were studied under in vitro conditions using sera from the final hostAnguilla anguilla and from two accidental fish hosts as well as fetal calf serum. As controls larvae were also kept in medium in the absence of serum and in experimentally infected eels. Sera from the accidental fish hosts carp and rainbow trout exerted toxic effects on the acanthocephalans. Worms maintained in medium containing sera from these two fish were contracted and displayed inverted probosces. Moreover, the tegument exhibited vacuolization and the formation of necrotic areas, including lysis of the mitochondria. Due to these effects, the parasites died at 21 (rainbow trout) or 21–50 days (carp) postincubation. Eel sera had no toxic effect on the infective larvae. The growth of the larvae in medium depended on the composition of the latter, but was reduced as compared with that in the natural final host. Based on these results, we conclude that components of the hosts' blood sera play a role in the determination of the host specificity ofP. ambiguus.