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Biomedical subjects

R Wieme

Publications and source records attributed to R Wieme.

13 recordsLinked to original sources
PubMed2005

Determination of the relative amounts of three crystal forms of a benzimidazole drug in complex finished formulations by FT-Raman spectroscopy.

A 5% (m/m) premix for animal use was quantitatively characterized for the polymorph composition of its benzimidazole drug substance. Raman spectra of reference samples (pure polymorphs A, B and C in lactose at a concentration of 5%, m/m) were compared with the spectra of benzimidazole samples with a known polymorph composition and with the spectra of uncharacterized premixes. The raw intensities of 78 selected wavenumbers were vector-normalized and application of stepwise linear regression models estimated the relative quantities of the benzimidazole-drug polymorphs A, B and C in the different samples. Modelling results of the samples with known polymorph composition were in compliance with the expected concentrations, validating the proposed methodology. The benzimidazole drug substance in the premixes was predominantly polymorph B. Although statistically not significant, some traces of polymorph A could not be ruled out. Similar analyses were performed to evaluate the solid-state stability of the benzimidazole drug substance in another drug formulation, i.e. a suspension-emulsion. Suspension-emulsions originally determined as containing polymorph B benzimidazole drug substance were stored for 12 months at 25 degrees C/60%RH. FT-Raman spectroscopy revealed that no polymorph transformations occurred during this storage.

Benzimidazoles↗
PubMed1996

The research in semantics behind the OpenLabs coding system.

The OpenLabs coding system is an established, comprehensive, dynamic, flexible, open, multilingual European system which is tailored to meet the electronic data interchange (EDI) needs of medical laboratory users. The OpenLabs coding system, having many specific, independent classes and considerable flexibility, serves two different objectives: (i) unambiguous coding of entities present in messages used for EDI in clinical pathology; and (ii) interfacing with other nomenclatures and coding schemes to map concepts between different systems.

Classification↗
PubMed1991

Humoral immune response against contractile proteins (actin and myosin) during cardiovascular disease.

Sensitive and highly specific ELISA assays were developed to determine humoral immune response against actin and myosin in 122 patients suffering from various cardiovascular diseases: acute viral myocarditis (n = 10, MYO), acute myocardial infarction (n = 28, AMI), valve surgery (n = 35, VALVE), coronary bypass surgery (n = 35, CABG), and peripheral vascular surgery (n = 14, VASC). Anti-actin and anti-myosin antibodies were determined on admission and serially during a period of 90 days. Anti-actin and anti-myosin immune response (IgG, IgM) was expressed comparing absorbance of the patients' serum with a reference serum. In the different patient groups significantly (P less than 0.01) higher anti-actin and anti-myosin antibody concentrations were found on admission compared with age-matched control groups. During follow-up, all patient groups except the vascular surgery group showed a significant immune response against actin and myosin, with an immune response ratio (peak/admission) for AMA IgG and IgM respectively of 2.12 and 2.40 in the VALVE group, 1.30 and 1.99 in the CABG group, 1.42 and 1.48 in the AMI group and 1.66 and 1.25 in the MYO group; and for AAA IgG and IgM respectively of 1.57 and 3.00 in the VALVE group, 1.54 and 1.64 in the CABG group, 1.25 and 1.07 in the AMI group, and 1.42 and 1.42 in the MYO group. A significant correlation between pre-cardiac injury and peak post-cardiac injury anti-myosin and anti-actin autoantibody levels could be demonstrated suggesting that pre-injury sensitization to these antigens plays an important role in evoking post-cardiac injury immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1988

Creatine determinations as an early marker for the diagnosis of acute myocardial infarction.

In the acute phase of acute myocardial infarction (3-8 h after onset of symptoms) an early transient increase in the creatine concentration of serum, saliva, and especially of urine can be observed. Due to the renal threshold, urine values give a much better discrimination between infarction patients and controls than do serum determination. In some patients secondary peaks of serum and urine creatine concentrations can be seen about 24-36 h after hospital admission. Intramuscular injections of 5.0 mL of a saline solution and muscular trauma interfere with the test, but with angina pectoris interference is absent or limited. Creatine leakage from myocardium is insufficient to explain the observed creatinuria in infarctions, and intact extra-cardiac tissues are believed to be involved in creatine release.

Adolescent↗
PubMed1988

Measurement of activation energy of gamma-glutamyltransferase as a marker for enzyme heterogeneity.

In order to detect differences between various multiple forms of gamma-glutamyltransferase, the activation energy was measured. In the serum of patients with liver diseases, activation energy was measured. In the serum of patients with liver diseases, activation energy of the serum enzyme is higher than in normal individuals (41.9 +/- 1.2 vs. 38.9 +/- 1.5 kJ/mol, p less than 0.05). Neuraminidase treatment resulted in a reduction of activation energy. Various multiple forms of serum gamma-glutamyltransferase, as prepared by lectin affinity chromatography (concanavalin A, Ricinus communis I and II, wheat germ agglutinin) showed activation energy differences between binding and nonbinding fractions. Similar results were observed in seminal plasma gamma-glutamyltransferase, when patients with accessory gland infection were compared with a reference population. Our results suggest that the activation energy depends upon differences in the carbohydrate part of the enzyme. The low gamma-glutamyltransferase activation energy of tissue extracts increased significantly after butanol extraction and was then comparable with serum activation energy values, which suggests that lipid-binding is a factor in activation energy variation. In most cases, gamma-glutamyltransferase activities measured at a certain temperature can be easily converted to a corresponding activity at another temperature, but in severe liver disease significant errors may be introduced when simple temperature conversion factors are used.

Chromatography, Affinity↗
PubMed1985

Detection of anti-contractile antibodies after cardiac surgery using ELISA assay.

Sera from 196 patients were collected before and after cardiac surgery to measure antibodies against heart tissue and against actin and myosin. In the post-operative period antibodies were found in 87 patients (44%) producing a cross-striated fluorescence pattern in heart tissue. Antibodies against the major contractile proteins were found in 91 patients (46%), anti-actin antibodies in 49 patients (25%) and anti-myosin antibodies in 65 patients (33%). We found a significant correlation (P less than 0.0001) between the antibodies producing a cross-striated fluorescence pattern and antibodies recognizing contractile proteins. These results suggest that contractile proteins evoke an immune response after cardiac surgery and that this response may compromise cardiac function.

Actins↗
PubMed1974

Chronic liver disease and hepatitis-B antigen: a prospective study.

A long-term follow-up of 45 patients with chronic hepatitis and 41 with cirrhosis is reported. Hepatitis-B antigen (HBAg) was present in 19 (42%) of the chronic hepatitis patients and in 20 (49%) of those with cirrhosis. The clinical course and biochemical and histological findings in the HBAg-positive and the HBAg-negative cases were similar, suggesting that HBAg-positive chronic liver disease is not a distinct clinical entity. The presence of antigen and autoantibodies was not found to be mutually exclusive. In HBAg-positive cases antigen tended to persist for months and years. When no irreversible lesions exist disappearance of the antigen may be a sign that the liver disease will resolve.

Adult↗