Biomedical subjects

G Koehler

Publications and source records attributed to G Koehler.

9 recordsLinked to original sources

PubMed2004

High level of beta-hCG simulating pregnancy in recurrent osteosarcoma: case report and review of literature.

PURPOSE: A high serum level of beta human chorionic gonadotropin (hCG) normally indicates pregnancy in healthy women. We were confused by this finding in one of our patients. This 18-year-old girl presented with amenorrhoea of 1-month duration, a positive pregnancy test and a high beta-hCG serum level although taking contraceptives. Pregnancy was excluded by ultrasound. Three years previously, she had had an osteosarcoma of the humerus. The tumour initially had been wide resected and had shown a good response to neoadjuvant chemotherapy with COSS-96-protocol. METHODS: We reviewed the original histological result and the literature about possible similar findings. We analysed therapeutic options and the value of beta-hCG levels as a therapy monitor. RESULTS: During examination we detected a recurrent osteosarcoma of the left humerus. The local relapse evidently expressed beta-hCG which, retrospectively, could only sparsely be shown in the primary resectate. After intralesional surgery, chemotherapy and radiotherapy levels of beta-hCG normalised. CONCLUSION: Osteosarcoma very rarely is able to produce a paraneoplastic syndrome by high levels of beta-hCG. This may well be of diagnostic value and offer an additional monitoring tool. It can indicate tumour recurrence and dedifferentiation.

Adolescent↗

PubMed2001

Whole-body 18F dopa PET for detection of gastrointestinal carcinoid tumors.

PURPOSE: To evaluate fluorine 18 (18F) dopa positron emission tomography (PET) in comparison with established imaging procedures in gastrointestinal carcinoid tumors. MATERIALS AND METHODS: After evaluation of the normal distribution of 18F dopa, 17 patients with histologically confirmed tumors were examined with 18F dopa PET. Results of 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) PET, somatostatin-receptor scintigraphy, and morphologic imaging (computed tomography and/or magnetic resonance imaging) were available for all patients. Results of the procedures were evaluated by two radiologists and two nuclear medicine specialists, whose consensus based on all available histologic, imaging, and follow-up findings was used as the reference standard. RESULTS: Ninety-two tumors were diagnosed: eight primary tumors, 47 lymph node metastases, and 37 organ metastases. 18F dopa PET led to 60 true-positive findings (seven primary tumors, 41 lymph node metastases, 12 organ metastases); FDG PET, 27 (two primary tumors, 14 lymph node metastases, 11 organ metastases); somatostatin-receptor scintigraphy, 52 (four primary tumors, 27 lymph node metastases, 21 organ metastases); and morphologic imaging, 67 (two primary tumors, 29 lymph node metastases, 36 organ metastases). This resulted in the following overall sensitivities: 18F dopa PET, 65% (60 of 92); FDG PET, 29% (27 of 92); somatostatin-receptor scintigraphy, 57% (52 of 92); morphologic procedures, 73% (67 of 92). Although the morphologic procedures were most sensitive for organ metastases, 18F dopa PET enabled best localization of primary tumors and lymph node staging. CONCLUSION: 18F dopa PET is a promising procedure and useful supplement to morphologic methods in diagnostic imaging of gastrointestinal carcinoid tumors.

Adult↗

PubMed2000

An automated technique for measuring deltaD and delta18O values of porewater by direct CO2 and H2 equilibration.

The stable-oxygen and -hydrogen isotopic values (deltaD, delta18O) of porewater in geologic media are commonly determined on water obtained by extraction techniques such as centrifugation, mechanical squeezing, vacuum heating and cryogenic microdistillation, and azeotropic distillation. Each of these techniques may cause isotopic fractionation as part the extraction process and each is laborious. Here we demonstrate a new approach to obtain automated, high-precision deltaD and delta18O measurements of porewater in geologic sediments by direct H2- and CO2-porewater equilibration using a modified commercial CO2-water equilibrator. This technique provides an important and cost-effective improvement over current extraction methods, because many samples can be rapidly analyzed with minimal handling, thereby reducing errors and potential for isotopic fractionation. The precision and accuracy of direct H2- and CO2-porewater equilibration is comparable to or better than current porewater extraction methods. Finally, the direct equilibration technique allows investigators to obtain high-resolution (cm scale) porewater deltaD and delta18O profiles using cores from individual boreholes, eliminating the need for costly piezometers or conventional porewater extractions.

Journal Article↗

PubMed1999

The effects of critical incident stress debriefing (CISD) on emergency medical services personnel following the Los Angeles Civil Disturbance.

This study examined the effects of Critical Incident Stress Debriefing (CISD) upon technicians who provided emergency medical services in South Central Los Angeles during the 1992 Los Angeles Civil Disturbance. The relationships between exposure, debriefing and symptoms of stress were identified and examined. The Frederick Reaction Index-Adult (FRI-A) was used to measure the presence of symptoms characteristic of posttraumatic stress disorder. EMTs who had the opportunity to participate in Critical Incident Stress Debriefings (n = 42) following the incident reported fewer symptoms and scored significantly lower on the FRI-A than those not participating in Critical Incident Stress Debriefing (n = 23).

Crisis Intervention↗

PubMed1994

The role of interleukin-6 in mucosal IgA antibody responses in vivo.

In mice with targeted disruption of the gene that encodes interleukin-6 (IL-6), greatly reduced numbers of immunoglobulin A (IgA)-producing cells were observed at mucosae and grossly deficient local antibody responses were recorded after mucosal challenge with either ovalbumin or vaccinia virus. The IgA response in the lungs was completely restored after intranasal infection with recombinant vaccinia viruses engineered to express IL-6. These findings demonstrate a critical role for IL-6 in vivo in the development of local IgA antibody responses and illustrate the effectiveness of vector-directed cytokine gene therapy.

Animals↗

PubMed1994

Interleukin-6 is required in vivo for the regulation of stem cells and committed progenitors of the hematopoietic system.

The development of blood cells from hematopoietic stem cells is controlled by multiple cytokines. These growth factors influence survival, cell cycle status, differentiation into lineage-committed progenitors, final maturation into blood cells, and perhaps self-renewal of stem cells. The specific contribution of IL-6 to these processes in vivo was evaluated in mice with a targeted disruption of the IL-6 gene. Decreases in the absolute numbers of CFU-Sd12 and preCFU-S, as well as in the functionality of LTRSC in these mutant mice, suggests a role for IL-6 in the survival, self-renewal, or both of hematopoietic stem cells and early progenitors. In addition, as a result of the IL-6 deficiency, the control between proliferation and differentiation of the progenitor cells of the granulocytic-monocytic, megakaryocytic, and erythroid lineages into mature blood cells is altered, leading to abnormal levels of committed progenitors of these lineages and to a slow recovery from hematopoietic ablation.

Animals↗

PubMed1993

Resistance of mice deficient in IL-4 to retrovirus-induced immunodeficiency syndrome (MAIDS)

The murine acquired immunodeficiency syndrome (MAIDS) is induced by a defective murine leukemia virus and has many symptoms similar to those found in patients infected with the human immunodeficiency virus. The presence of both B cells and CD4+ T cells is critical for the development of the disease. Furthermore, a Th2 cytokine response dominates during the progression of the disease. When interleukin-4 (IL-4)-deficient mice that are defective in Th2 cytokine responses were infected, there was no lethality, and the development of the T cell abnormalities associated with MAIDS was delayed. These data suggest that IL-4 or a Th2 response is involved in the development of retrovirus-induced immunodeficiency in mice.

Animals↗

PubMed1991

Pharmacokinetics of diflunisal in patients.

There are few pharmacokinetic data available on the disposition of diflunisal in patients; this study, therefore, looked at the oral absorption, distribution and elimination of this drug. Ten pharmacokinetic profiles obtained from 8 patients showed a maximum plasma diflunisal concentration of 62.0 +/- 26.5 mg/L after 2.76 +/- 1.87 hours, and an area under the plasma concentration-time curve (AUC) of 678.3 +/- 362.3 mg/L.h. Significant intra- and intersubject variability was observed in this group of patients. Analysis of biliary secretion of diflunisal in 4 patients suggested a biliary elimination and subsequent enterohepatic circulation ranging between 2.4 and 15.1%. The AUC for diflunisal in synovial fluid collected from 66 patients was about 70% of that for plasma. In none of 28 patients studied could any trace of diflunisal be observed in cerebrospinal fluid, even though the sensitivity of the assay allowed detection of concentrations as low as 0.01 mg/L.

Adult↗

PubMedDate not supplied

Guidelines for the development of comparative pathology.

The purpose of comparative pathology is to develop a fuller understanding of pathologic processes in individuals of various species. Historically, we distinguish between direct and indirect findings. Direct sources are paleopathologic fossils. Indirect findings are historic and/or religious descriptions of epidemics. The philosophy behind the comparative approach depends primarily on the individuals of the species as units. The individual represents a concrete reality, whereas the other taxonomic categories are only theoretical entities contrived by human thought. Intraspecies-specific comparison and the interspecies-specific comparison are distinguishable. In intraspecies-specific comparison different individuals (races, breeds) of one species are compared, whereas in the interspecies-specific comparison individuals of several species are compared. Evolution and the comparative ontogenetic development of recent organisms explains how the variability of species came into existence. Consistency in evolution and uniformity is given by the fact that members of all phyla are still represented by some remaining species. Heterogeneity of organismic structures are more numerous but secondary. With the exception of the virus, the cell is remaining the unit of living matter, but viruses depend on cells for their existence. The majority of species, the eumetazoans and vascular plants, are built of true tissues developed by cell division, whereas higher fungi and some algae exhibit plectenchymata which develop by the fusion of cells. This short article presents some thoughts and principles underlining the importance of development of guideline for the study of comparative pathology.

Animals↗