Ein Pyramidenzeichen an der Hand

Ohne Zusammenfassung     

Über die sensible Leitung in den vorderen Wurzeln

Ohne Zusammenfassung     

Bücherbesprechungen

Ohne Zusammenfassung     

Ein Kleinhirnsymptom

Ohne Zusammenfassung     

Residential magnetic fields and childhood leukemia: a meta-analysis.

OBJECTIVES: This article uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies of residential magnetic field exposure and childhood leukemia. METHODS: A variety of meta-analytic statistical methods were applied to all available studies combined and on sub-groups of studies chosen by exposure characteristics. Sample sizes and fail-safe n's were calculated to determine the robustness of results and the potential role of publication bias. RESULTS: Most studies show elevated but not statistically significant odds ratios. Results for exposures assessed by wire codes, distance, and/or historically reconstructed fields are relatively consistent, homogeneous, and positive, while those for direct magnetic field measurements are consistent, homogeneous, and marginally protective. Several unpublished studies, or a single unpublished study with several hundred subjects, would be needed to nullify the observed data. CONCLUSIONS: The observed results identify a consistent risk that cannot be explained by random variation. The data supporting magnetic fields as the principal risk factor are suggestive but inconsistent. Additional studies using innovative designs that focus on highly exposed children offer the most hope of untangling this issue.     

Is Magnetic Resonance Spectroscopy Superior to Conventional Diagnostic Tools in Hypoxic‐Ischemic Encephalopathy?

Anoxic brain injury carries a poor prognosis. Therefore, a diagnostic tool sensitive enough to predict its outcome is needed. The authors describe the case of a 51-year-old woman who suffered cardiorespiratory arrest. Electroencephalography, somatosensory evoked potentials, and magnetic resonance imaging did not prove to be useful in establishing a definitive prognosis. Magnetic resonance spectroscopy demonstrated the presence of significant neuronal loss in the cortex and cerebellum and was the only diagnostic procedure closely associated with this patient's prognosis.     

Zur Cytologie der pr?natalen Gonaden-Entwicklung beim Menschen

Zusammenfassung Es wurden die Anlagen von 16 menschlichen, embryonalen und fetalen Hoden mit dem Elektronenmikroskop untersucht. Das Alter der Embryonen reichte von 40 Tagen bis zu 22 Wochen Ovulationsalter (OA). Untersucht wurden die cytologischen Veränderungen der männlichen Keimzelle. Dabei gelang eine eindeutige Abgrenzung von zwei Geschlechtszelltypen durch cytomorphologische Kriterie: Gonocyten findet man vorwiegend bis zur 12. Woche. Sie sind in einer I. Phase überwiegend frei von Glykogen und in einer 2. Phase etwa ab dem 45. Tag OA durch zunehmende Glykogeneinlagerung im Cytoplasma charakterisiert. In einer 3. Phase ab der 10.–12. Woche treten neben den Gonocyten fetale Spermatogonien auf, die ab der 18. Woche etwa ein Drittel der vorhandenen Geschlechtszellen ausmachen. Fetale Spermatogonien sind an einem lockeren Kern, an der veränderten Mitochondrienstruktur, dem Auftreten von intermitochondrialer Substanz und intercellulären Brücken sowie dem Fehlen von Glykogen zu erkennen. Ein Teil dieser fetalen Spermatogonien zeigt degenerative Zellveränderungen, die als Zeichen eines späteren Zelltodes gewertet werden. Die Frage, ob Gonocyten oder fetale Spermatogonien den Zellpool darstellen, aus dem sich die Spermatogonien des postnatalen und adulten Hodens entwickeln und ableiten, wird diskutiert, kann aber mit dem vorhandenen Material und den Ergebnissen nicht beantwortet werden.

---

On the cytology of the prenatal development of human gonadsII. Electronmicroscopic studies on the cytogenesis of gonocytes and foetal spermatogonia in the testis

Summary The anlagen of 16 human testes of embryos and foetus have been studied electronmicroscopically. The age of embryos extends from 40 days to 22 weeks of ovulation age. It has been studied the cytological variations of the male germ cells. Two typs of germ cells can be distinguished clearly by cytomorphological criteria: Up to the 12th week gonocytes have been identified mostly. In a 2nd period with the begin of 45th day ovulation age they are characterized by an increasing amount of glycogen deposities in the cytoplasm. During a 3rd period beginning with week 10 to 12 foetal spermatogonia occur besides gonocytes, which constitute one third of the existing germcells from the 18th week. Foetal spermatogonia can be recognized by their light nucleus, by mitochondria which have altered their structure and which are connected by intermitochondrial cement, by the occurrence of intercellular bridges and by the absence of glycogen deposities. Some of the foetal spermatogonia display degenerative alterations of the cytoplasmic organells which indicate the future death of the cell. The question wether or not gonocytes or foetal spermatogonia exhibit a pool of cells from which spermatogonia of the postnatal and adult testis develope has been discussed, however, it cannot be answered on the basis of the present material and its results.

Herrn Prof. Dr. G. Wolf-Heidegger mit den besten Glückwünschen zum 60. Geburtstag gewidmet.     

A retrospective occupational cohort study of end-stage renal disease in aircraft workers exposed to trichloroethylene and other hydrocarbons

OBJECTIVE: Case-control studies suggest hydrocarbons increase end-stage renal disease (ESRD) risk. No cohort studies have been conducted. METHODS: An occupational database was matched to the U.S. Renal Data System, and the outcome of all-cause ESRD was examined using multivariable Cox regression. Sixteen individual hydrocarbons were studied, although exposures were not mutually exclusive. RESULTS: For the 1973-2000 period, there was an approximate twofold increased risk of ESRD among workers exposed to trichloroethylene, 1,1,1-trichloroethane, and JP4 gasoline compared with unexposed subjects (all P < 0.05). Relative risk was greater than unity (P > 0.05) for several other hydrocarbons. Associations attenuated (all P > 0.05) when 2001-2002 data were included in the analyses. CONCLUSIONS: Certain hydrocarbons may increase all-cause ESRD risk. Uncertainty regarding the mechanism for increased risk and the observed attenuation in risk in 2001-2002, as well as the overlap of exposures, complicates interpretation. Additional research is needed.