PubMed Health⌕ Search

Biomedical subjects

M Hempel

Publications and source records attributed to M Hempel.

At least 19 recordsLinked to original sources
PubMed2005

Fulminant lactic acidosis in two patients with Type 2 diabetes treated with metformin.

Lactic acidosis is a known adverse risk of metformin treatment. We report two cases in whom fulminant lactic acidosis developed during treatment. There were no contraindications to metformin treatment and both were admitted with abdominal discomfort for some days, causing dehydration. Both patients had renal failure on admission, developed multiple organ failure and both suffered a massive stroke. One patient died and the other survived but is severely disabled. We suggest, in both cases, that acute renal failure developed as a result of dehydration, causing metformin accumulation and lactic acidosis. We recommend that all patients on metformin should consider discontinuation of metformin treatment in the event of a severe medical condition causing dehydration.

Acidosis, Lactic↗
PubMed2002

Photodynamic therapy using topical methyl 5-aminolevulinate compared with cryotherapy for actinic keratosis: A prospective, randomized study.

BACKGROUND: Actinic keratoses (AKs) are the most common premalignant tumors. Without treatment, a significant number of patients with AK will experience squamous cell carcinoma. Photodynamic therapy (PDT) using the new highly selective photosensitizer methyl 5-aminolevulinate is a promising new treatment modality for AK. OBJECTIVE: We investigated the complete response rates, cosmetic outcome, and patient satisfaction after photodynamic therapy (PDT) using methyl 5-aminolevulinate (Metvix) versus cryotherapy in the treatment of AKs. METHODS: Patients were randomized to receive either cryotherapy with liquid nitrogen spray or PDT using methyl 5-aminolevulinate cream 160 mg/g, 3 hours application time, and red light (75 J/cm(2)). RESULTS: Efficacy results from 193 patients with 699 lesions (92% face/scalp and 93% thin/moderately thick) were analyzed. Overall complete response rates after 3 months were 69% for PDT and 75% for cryotherapy. Both treatments gave higher response rates in thin lesions (PDT 75%, cryotherapy 80%). PDT gave better cosmetic results and higher patient satisfaction than cryotherapy. CONCLUSION: PDT using methyl 5-aminolevulinate is an attractive treatment option for patients with AK, with a response rate similar to that of cryotherapy, but with superior cosmetic results and high patient satisfaction.

Administration, Topical↗
PubMed2000

Isolation and characterization of glycosylphosphatidylinositol-anchored, mucin-like surface glycoproteins from bloodstream forms of the freshwater-fish parasite Trypanosoma carassii.

Wild and farmed freshwater fishes are widely and heavily parasitized by the haemoflagellate Trypanosoma carassii. In contrast, common carp, a natural host, can effectively control experimental infections by the production of specific anti-parasite antibodies. In this study we have identified and partially characterized mucin-like glycoproteins which are expressed in high abundance [(6. 0+/-1.7)x10(6) molecules.cell(-1)] at the surface of the bloodstream trypomastigote stage of the parasite. The polypeptide backbone of these glycoproteins is dominated by threonine, glycine, serine, alanine, valine and proline residues, and is modified at its C-terminus by a glycosylphosphatidylinositol membrane anchor. On average, each polypeptide carries carbohydrate chains composed of about 200 monosaccharide units (galactose, N-acetylglucosamine, xylose, sialic acid, fucose, mannose and arabinose), which are most probably O-linked to hydroxy amino acids. The mucin-like molecules are the target of the fish's humoral immune response, but do not undergo antigenic variation akin to that observed for the variant surface glycoprotein in salivarian trypanosomes. The results are discussed with reference to the differences between natural and experimental infections, and in relation to the recently delineated molecular phylogeny of trypanosomes.

Amino Acids↗
PubMed2000

On-line determination of mercury in river water at the German monitoring station Schnackenburg/Elbe.

A monitor is described which provides the on-line determination of mercury in river water at concentrations from 20 to 1000 ng/L. The measurement includes an on-line digestion with Br-/BrO3- and UV-radiation. Each determination is controlled by an on-line addition of 50 and 100 ng/L mercury carried out by pre-dilution of a 500 and 1000 ng/L stock solution using sequential injection analysis (SIA). One cycle of analysis takes 20 min and results in nine signals. A five days stand-alone operation has been performed successfully. Details are also published at web page: "http/www.rzbd.fh-hamburg.de/-prmercol".

Environmental Monitoring↗
PubMed2000

Discovery of a transalkylation mechanism--identification of ethylmercury+ at a tetraethyllead-contaminated site using sodiumtetrapropylborate, GC-AED and HPLC-AFS.

Although organolead as a gasoline additive is banned in most countries, contamination by organolead compounds is still present. Little is known about transformation reactions of organolead compounds and especially transalkylation reactions with other metals. Laboratory experiments to clarify transalkylation reactions between organolead and inorganic mercury, and investigations of sites, where organolead compounds were emitted, are reported. Under laboratory conditions, inorganic mercury is ethylated to ethylmercury+ in presence of tetraethyllead. These transalkylations take place very fast and almost completely. In soil samples from an industrial site contaminated with organolead compounds and inorganic mercury, EtHg+ was clearly identified in high concentrations (up to 46 mg Hg/kg dw). Furthermore, methylmercury+ was found in concentrations up to 27 mg Hg/kg dw. It is the first time, that a transethylation of an organolead compound to an organomercurial compound in the environment is reported. It must be assumed, that this transalkylation takes place at sites, where organolead compounds occur and Hg2+ is available. Thus, it will be necessary to assess the risk of these sites.

Journal Article↗
PubMed1995

Toxicity of organomercury compounds: bioassay results as a basis for risk assessment.

A former mercury plant, where mercury salts and organomercurials for pesticide use were produced, caused soil contamination in high concentrations. Typical organomercurial products included ethylmercury, phenylmercury, methoxyethylmercury and ethoxyethylmercury compounds. Risk assessment of these sites must be carried out before any major clean-up processes can be planned. A sensitive speciation technique for the various organomercury species in environmental matrices is a prerequisite for toxicity investigations. In this connection, a high-performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) technique has been developed to differentiate between and determine the presence of eight organomercury compounds in environmental samples. Using this technique, methylmercury, ethylmercury and phenylmercury and some unknown organomercury species were found in soil samples collected from the sites of an old mercury products producing plant. With regard to risk assessment, it is necessary to assess the toxicity of the organomercurials. As different microbial metabolic pathways react differently to mercury and its compounds, batteries of bioassays are, therefore, useful to evaluate the toxicity of pollutants. To describe the toxicity and genotoxicity of MeHg+, MeOEtHg+, EtHg+, EtOEtHg+ and PhHg+, p-tolymercury chloride, nitromersol and Hg2+ six bioassays were used: resazurin reduction method, Spirillum volutans test, nematode toxicity assay Panagrellus redivivus, Toxi-Chromotest and SOS-Chromotest. A ranking of the toxicity of the organomercurial is shown. The SOS-Chromotest indicated genotoxicity for 5-7 organomercurials.

Animals↗
PubMed1994

Behavioral effects of an antiandrogen in adult male rhesus macaques (Macaca mulatta).

This study was designed to determine how to suppress behavioral effects of androgens with a pure non-steroidal antiandrogen, Hydroxyflutamide (OHF). The major dependent variable was yawning behavior of castrated adult male rhesus macaques. Injections of testosterone propionate (TP) increased yawning frequency and cessation of TP injections produced a decrease in yawning frequency. A similar decrease was observed with simultaneous injections of TP and OHF. It has been found that the dose of OHF injected subcutaneously should be 80 times that of TP to block the effects of either physiological or supraphysiological doses of TP.

Androgen Antagonists↗
PubMed1993

Eye sequelae following external irradiation.

The early reactions of the eye to radiation are conjunctivitis and, with higher doses, corneal damage. The inflammatory reactions are transient and remit within a few weeks after the end of radiotherapy. Doses above 60 Gy can produce corneal ulcerations with the risk of perforation and loss of the eye. The most frequent late reaction of the eye is cataract of the lens. The tolerance dose (about 5 Gy) is extremely low and the latent period varies from 6 months to 3 years. The lens in children has a much lower tolerance. The increasing potential for optical support and ophthalmic surgery over recent decades has reduced the fear of this complication. The most severe late complications are retinopathy (RR) and neuropathy of the optic nerve (RON), both of which are caused by radiation-induced microangiopathy. Visual loss is very frequent and complete blindness is seen with high doses in the range of 50-60 Gy. The latent period of these injuries varies widely from 1 month to 15 years, but they usually occur within 3 years of treatment. Conflicting frequencies are reported in the literature. Beyond 30 Gy, usually no RR is seen. However, the lowest recorded dose producing RR is 11 Gy. In the high dose range of 60-70 Gy RR and RON are found in 10%-100% of patients. There is a great need for prospective trials to estimate the true risk to patients with nasopharyngeal, maxillo-ethmoidal, and orbital tumors, pituitary adenomas, and tumors of the salivary glands. To minimize complications of radiotherapy to the eyes daily fractions should be reduced to 1.7-1.8Gy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Determination of organic mercury species in soils by high-performance liquid chromatography with ultraviolet detection.

Reversed-phase high-performance liquid chromatography with ultraviolet detection was optimized for the simultaneous separation and quantification of nine organic mercury compounds: methyl-, ethyl-, phenyl-, methoxyethyl-, ethoxyethyl-, benzoic and tolylmercury, mersalylic acid and nitromersol. The nine compounds were successfully separated on octadecylsilane columns (200 x 3 mm i.d.) by gradient elution with a methanol-water mixture ranging from 30 to 50% v/v. The detection limits for the various compounds are in the range 7.0-95.1 micrograms dm-3. For the extraction of five organomercurials from spiked soils, eight different extraction solutions were tested to differentiate between the total content and the available/soluble fraction of the analytes. Ammonium acetate solutions (1 mol dm-3) and water proved to be suitable agents for the estimation of the available and soluble fractions of methyl-, ethyl-, benzoic, methoxyethyl- and ethoxyethylmercury. For the determination of the total content of methyl- and benzoic mercury in soils, solutions of potassium iodide (1 mol dm-3)-ascorbic acid (0.1 mol dm-3) and oxalic acid (1 mol dm-3) provided recoveries in the ranges 53-81%. None of the solutions tested is suitable for the extraction of ethyl-, methoxyethyl- and ethoxyethylmercury.

Chromatography, High Pressure Liquid↗
PubMed1989

[Clinical relevance of determining lymphocyte subpopulations in peripheral blood of patients with rheumatoid arthritis].

Blood lymphocytes were determined from 21 patients with seropositive rheumatoid arthritis (RA) in a cross-sectional study with 5 monoclonal antibodies (MAb) of the BL-series. 7 patients were examined with the same MAb over a time period of 14 weeks before and after a prednisolone-pulse therapy. The cross-sectional study showed a significant higher percentage of Ia4+ T-helper/inducer-lymphocytes in RA-patients compared to control persons. The value of Ia4+ T-lymphocytes didn't correlate to the clinical activity of the RA. No significant differences were observed in the helper/suppressor T-lymphocyte ratio. The lymphocyte subpopulations were not significantly different immediately before and after a prednisolone-pulse therapy. The percentage of B-lymphocytes was significantly higher in comparison to the controls 24 h after prednisolone-pulse therapy. An immunomonitoring of the clinical activity and the therapy of RA is not possible with the used MAb.

Adult↗
PubMed1976

[Qualitative demands on a anti-N blood group test reagent from Vicia graminea (anti N vg)].

Qualitative demands made on anti-NVg are enunciated. Apart from a short description of the production and directions for the use indications for testing the specific effect, the purity and the titre are given. Furthermore, serological peculiarities of the anti-NVg for special questions are reported. Anti-NVg shall enlarge the series of the out superseding the usual anti-N-serum of the blood-group-serological diagnostic remedies with-rabbit.

Agglutinins↗