Biomedical subjects

H J Schaefer

Publications and source records attributed to H J Schaefer.

At least 19 recordsLinked to original sources

PubMed2005

Hepatoblastoma in a child with progressive familial intrahepatic cholestasis.

End-stage liver cirrhosis because of metabolic or infectious diseases predisposes to hepatic malignancies like hepatocellular carcinoma. We report the first case of hepatoblastoma incidentally detected in the explanted liver of a 2-yr-old child undergoing liver transplantation for cirrhosis because of progressive familial intrahepatic cholestasis (PFIC). The diagnosis was difficult to obtain. The hepatoblastoma was not seen on ultrasound examination of the cirrhotic liver. As we could confirm retrospectively, alpha fetoprotein (AFP) was found elevated prior to transplantation. Two years after successful transplantation, there are no signs of malignancy detectable by clinical and radiological methods. We conclude from this case that PFIC may induce hepatoblastoma and that children with liver cirrhosis should undergo routine screening of serum AFP concentration.

Child, Preschool↗

PubMed1988

[Oral polychemotherapy in far advanced recurrences of Hodgkin's disease].

In 10 patients with heavily pretreated Hodgkin's disease (stage IVA or IVB) a third-line salvage therapy consisting of CCNU, etoposide and chlorambucil (CECh) was tested. All patients were resistant to both COPP and ABVD. Acceptance and tolerance of CECh were very satisfactory. The observed response rate (3 complete remissions and 4 partial remissions) is encouraging. The survival time after CECh therapy is in excess of 32 months (complete remission) and 15 months (partial remission). The main possible adverse effect is a prolonged myelosuppression. The CECh therapy is an effective alternative chemotherapy in patients resistant to both COPP and ABVD, moderately toxic, easy to administer and well tolerated in heavily pretreated patients.

Administration, Oral↗

PubMed1987

Persistent active Epstein-Barr virus infection and atypical lymphoproliferation. Report of two cases.

Two cases of what is apparently Epstein-Barr virus (EBV)-associated atypical lymphoproliferation which clinically suggested malignant lymphoma are discussed. Immunohistology revealed polyclonal T- and B-cell proliferation resembling progressive infectious mononucleosis. Giant cell formation and marked plasmacytosis was suggestive of Hodgkin's disease. EBV serology was initially not diagnostic, but during the course of the disease, elevated titers against early antigens and EBV-associated nuclear antigen suggested virus replication. EBV DNA was demonstrated in lymphoid cells of both cases by in situ hybridization. One case progressed to overt monoclonal B-cell malignant lymphoma. Atypical polyclonal lymphoproliferation in persistent active EBV infection may thus be considered a prelymphomatous condition.

Antigens, Viral↗

PubMed1987

Interaction of Tangier lipoproteins with cholesteryl ester-laden mouse peritoneal macrophages.

Cholesterol efflux was studied from cholesteryl esterladen mouse peritoneal macrophages in the presence of Tangier lipoproteins derived from fasting and postprandial sera of three patients homozygous for Tangier disease (analphalipoproteinemia). The d greater than 1.063 g/ml fractions isolated from fasting patients and 3 hr and 18 hr after an oral fat load were all effective in cellular cholesterol removal. By contrast, the d greater than 1.063 g/ml fractions isolated 6 hr and 12 hr after fat ingestion did not affect net removal of cellular cholesterol. The d greater than 1.21 g/ml protein fractions derived from fasting as well as postprandial sera were all effective in removing cholesterol. D 1.063-1.21 g/ml fractions from fasting Tangier patients contained HDLT. In the corresponding postprandial fractions, in addition to HDLT, apoB-100- and apoB-48-containing lipoproteins were present. Furthermore, the 6 hr and 12 hr postprandial Tangier HDL fractions contained apoB-immunoreactive proteins of lower molecular weight. The abnormal activity of the elastase/alpha 1-antitrypsin proteolytic system and the abnormal fibronectin concentration we found in Tangier plasma suggests a possible relationship to the in vivo degradation of apoB. The peculiar type of membrane-bound lipid droplets in Tangier splenic macrophages points to a lipoprotein source of lipid accumulation which possibly originates from the uptake of chylomicrons or chylomicron-derived particles. It is concluded that cholesteryl ester storage in Tangier macrophages results from an imbalance of cholesterol influx and efflux. In the absence of HDL, the net increase of cholesterol caused by abnormal lipoproteins in certain postprandial states cannot be fully compensated by effective efflux and ultimately leads to macrophage cholesteryl ester accumulation.

Adult↗

PubMed1979

[The distribution of material density and mechanical stress in the human radius during bending (author's transl)].

In a hypothetical mechanical system generated by computer, various kinds of loads are applied to 78 human Radii. The torque and bending stresses occuring at the surfaces of 390 cross-sections of the bone, taken from sites spaced at regular intervals along the bone shaft, are calculated and plotted. In this system, a load is rotated around the point of gravity of a cross-section. For each possible position of the load during the rotation, the total stresses occuring at the surfaces of the cross-sections are calculated and the position of the load causing minimal stress is determined. This position will be called "the most advantageous bending-plane". Furthermore, the variation of the cross-sectional surfaces and the moments of inertia are analysed.

Adolescent↗

PubMed1976

Microdosimetric structure of heavy ion tracks in tissue.

Energy dissipation in tracks of high energy heavy ions in tissue shows a lateral spread of several to many microns depending on the energy of the primary particle. Complete dosimetric characterization, therefore, requires in addition to the Linear Energy Transfer (LET) information on the radial energy distribution. The theory of track structure distinguishes two regions: core and penumbra. The core is a narrow central zone with a radius in tissue far below 1 micron where energy deposition occurs mainly in processes of excitation and electron plasma oscillation. According to the Equipartition Principle, half of the total energy dissipation accrues in this manner. The penumbra is a peripheral zone enveloping the core where energy deposition occurs mainly in ionization events by energetic secondary electrons released by the primary particle in the center of the core traveling at rather high speed thus spreading laterally. The extension of the penumbra depends in a complex manner on the maximum transferable energy to electrons which in turn depends on the speed of the primary particle. Local energy density in the penumbra decreases with the square of increasing radius. It therefore amounts only to a very small fraction of the core density already a few microns away from the center. In general terms, track structure can be described as exhibiting a core of enormous energy density with lateral dimensions remaining entirely on the submicroscopic level surrounded by a penumbra where energy density drops precipitously to very small levels. The relationships are illustrated with micrographs of different sections of a heavy particle track in nuclear emulsion and their counterpart graphical plots.

Elementary Particles↗

PubMed1975

Problems of component discrimination in space radiation dosimetry.

Resolving the LET spectrum of environmental radiation in space for assessing dose equivalents creates special problems due to superposition effects. Three components of the radiation field in space, trapped protons, tissue disintegration stars, and neutrons, contribute the bulk of the total dose equivalent. While lack of discrimination of neutron recoil and trapped primary protons does not interfere with correct determination of the combined dose equivalent as such, the simultaneous bursts of several low-energy protons and alpha particles from tissue disintegration stars completely defy LET-resolution with conventional instrumentation. So far, the tissue star dose has been determined only semiquantitatively from nuclear emulsion data. The neutron spectrum in space shows a markedly higher relative fluence in the region beyond 5 MeV than the fission neutron spectrum. Therefore, its LET spectrum centers less heavily on LET values near the proton Bragg Peak. This would call for assigning a QF value of less than 10 to the neutron dose in space. Still more serious shortcomings exist with regard to LET interpretation of heavy primaries.

Cosmic Radiation↗

PubMed1974