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Biomedical subjects

R Geyer

Publications and source records attributed to R Geyer.

134 records · Page 8Linked to original sources
PubMedDate not supplied

[The use of a rapid infusion system in orthopedics].

Major orthopedic surgery such as partial resection of the pelvis and subsequent implantation of a prosthesis is highly connected with massive bleeding. Therefore we tested the hypothesis that the use of a rapid infusion device, which was originally designed for liver transplantations, can prevent hypovolemic shock. We studied 20 patients: in one group (n = 10) the iv volume was given in a conventional way (37 degrees C) by use of pressure infusion bags. Patients of the second group (n = 10) received the iv volume via the Rapid Infusion system (Haemonetics Corp., Braintree, MA). We can conclude that with this new device for rapid volume replacement it is possible to keep the patient's vital functions stable even during times of excessive bleeding and to prevent from metabolic consequences following hypovolemic shock.

Adult↗
PubMedDate not supplied

An improved X-ray spectrometric method for the determination of bromide in whole blood of workers occupationally exposed to methyl bromide.

An X-ray spectrometric method using a sequential wavelength dispersive instrument is described for the analysis of bromide in whole blood from workers occupationally exposed to methyl bromide. The method involves the direct deposition of 100 microL of whole blood onto filter paper discs. Calibration of the instrument is achieved using the standard addition technique for bromide concentrations up to 50 mg/L. Precision studies at concentrations of 6.1, 16.4, and 26.9 mg/L gave relative standard deviation values of 5.8, 4.1, and 2.8%, respectively. The detection limit for the method is 1.2 mg/L.

Bromides↗
PubMedDate not supplied

An improved HPLC analysis of the metabolite furoic acid in the urine of workers occupationally exposed to furfural.

An improved high-performance liquid chromatographic (HPLC) method for the analysis of the metabolite furoic acid in the urine of workers occupationally exposed to furfural is described. The procedure involved an alkaline hydrolysis step followed by solvent extraction using ethyl acetate. HPLC analysis used an acidic acetonitrile/water mobile phase with a C18 column and ultraviolet detection. The overall relative recovery of furoic acid in urine was found to be 98.8% with a relative standard deviation of 9.7%. The limit of quantitation was determined to be 0.01 mmol/L.

Air Pollutants, Occupational↗
PubMedDate not supplied

Phosphine analysis in post mortem specimens following ingestion of aluminium phosphide.

Phosphine was detected in post mortem stomach and contents, blood, and liver specimens of a man who had ingested tablets containing aluminium phosphide. The phosphine was released from the samples after acid treatment and analysed by means of a headspace gas chromatographic technique using a nitrogen phosphorus detector.

Aluminum Compounds↗
PubMedDate not supplied

A multi-institutional retrospective study of intracranial ependymoma in children: identification of risk factors.

PURPOSE: The goal of this multi-institutional retrospective study of children with intracranial ependymoma was to identify risk factors associated with unfavorable overall survival (OS) and event-free survival (EFS). PATIENTS AND METHODS: Clinical data, including demographics, tumor location, spread, histology, details of surgery, radiation treatment, and chemotherapy were collected. Clinical characteristics and univariate and multivariate analyses of risk factors for OS and EFS are presented. RESULTS: Eleven U.S. institutions contributed 83 patients treated from 1987 to 1991. The OS at 5 and 7 years was 57% and 46%, and EFS at 5 and 7 years was 42% and 33%. Patients 3 years of age or younger differed from the older group by more common infratentorial location, less common gross total resection (GTR), and postoperative use of chemotherapy rather than radiation. This younger group of patients had worse survival (P < 0.01) than the older age group. Other than young age, less than GTR and World Health Organization (WHO) II grade 3 histology were significant adverse risk factors for EFS in univariate and multivariate analyses. OS shared the same adverse risk factors except for histology in multivariate analysis, which was only of borderline significance (P = 0.05). Progression at the original tumor location, present in 89% of patients, was the major pattern of tumor recurrence. Adjuvant chemotherapy in the group older than 3 years or craniospinal radiation in M0 patients did not significantly change EFS. CONCLUSIONS: Adverse outcome in childhood intracranial ependymoma is related to age (3 years or younger), histology (grade 3), and degree of surgical resection (less than GTR). New approaches, particularly for local tumor control in younger patients, are needed to improve survival.

Brain Neoplasms↗
PubMedDate not supplied

Phosphorylcholine substituents in nematodes: structures, occurrence and biological implications.

Phosphorylcholine (PC), a small haptenic molecule, is found in a wide variety of prokaryotic organisms, i. e. bacteria, and in eukaryotic parasites such as nematodes, as well as in fungi. Linked to parasite-specific glycoprotein glycans or glycolipids, it is assumed to be responsible for a variety of immunological effects, including invasion mechanisms and long-term persistence of parasites within the host. Numerous reports have indicated various effects of PC-substituted molecules derived from parasitic nematodes on signal transduction pathways in B and T lymphocytes, displaying a highly adapted and profound modulation of the immune system by these parasites. The Nematoda, comprising parasitic and free-living species, can be regarded as promising prototypic systems for structural analyses, immunological studies and biosynthetic investigations. In this context, Ascaris suum, the pig parasitic nematode, is an ideal organism for immunological studies and an excellent source for obtaining large amounts of PC-substituted (macro)molecules. Caenorhabditis elegans, as a completely genome-sequenced species and expressing parasite analogous PC-substituted structures, together with the possibility for easy in vitro cultivation, represents a conceptual model for biosynthetic studies, whereas filarial parasites represent important model systems for human pathogens, especially in developing countries. This review summarises current knowledge on the tissue-specific expression of PC epitopes, structural data of glycoprotein glycans and glycosphingolipids bearing this substituent and biological implications for the immune systems of the respective hosts.

Animals↗
PubMedDate not supplied

Capillary gas chromatographic determination of naphthalene in bran and wheat germ products.

A method is described for determining naphthalene in bran and wheat germ products. The method involves distilling the naphthalene from a water-cereal mixture and then extracting the distillate with hexane. A 10 microL aliquot of the hexane extract is injected into a gas chromatograph equipped with a capillary column. Dodecan-1-ol is used as the internal standard. Mean recoveries, standard deviations (SD), and coefficients of variation (CV) for samples of unprocessed bran, unprocessed wheat germ, bran flakes breakfast cereal, and sultana bran breakfast cereal, spiked with naphthalene at various levels, were 1.0 ppm spike, mean 0.98, SD 0.09, CV 9.5%; 2.5 ppm spike, mean 2.37, SD 0.22, CV 9.4%; 5.0 ppm spike, mean 4.86, SD 0.19, CV 4.0%; 10 ppm spike, mean 9.25, SD 0.38, CV 4.1%. The mean recoveries exceeded 90% in each case. The detection limit for the method was about 0.5 ppm.

Chromatography, Gas↗