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Biomedical subjects

R Walter

Publications and source records attributed to R Walter.

At least 91 records · Page 5Linked to original sources
PubMed1992

Pharmacokinetic interactions between isoniazid and theophylline in rats.

Pharmacokinetic interactions between isoniazid and theophylline were studied in male Wistar rats, 206 +/- 17 g. Concomitant oral administration of 2 x 5 mg kg-1 isoniazid accelerated slightly the disposition of theophylline (10 mg kg-1, i.v.) whereas 2 x 25 mg kg-1 isoniazid slowed it marginally. The differences in distribution volume, systemic clearance and area under the concentration-time curve (AUC) between the high and the low dose, however, were statistically significant. One week pretreatment with 10 mg kg-1 isoniazid tended towards inhibition (significant decrease of systemic clearance, increase of AUC) and 50 mg kg-1 to acceleration (decrease of half-life, mean residence time and AUC, increase of systemic clearance) of theophylline disposition. After oral pretreatment with 20 mg kg-1 theophylline, neither the kinetics of free isoniazid (50 mg kg-1, i.v.) and the amount acetylated nor the acetylation indices differed from the controls. There was no evidence that concomitant or subacute administration of different doses of isoniazid affects major metabolic pathways of theophylline or that prolonged theophylline treatment interacts with the N-acetylation capacity.

Animals↗
PubMed1991

Detection of hepatitis A virus and other enteroviruses in water by ssRNA probes.

Sensitive and specific methods are needed to detect hepatitis A virus (HAV) and other human enteroviruses in environmental samples such as drinking water and foods. Clones of cDNA encoding the 5'-most 1 kb of the HAV and coxsackievirus B3 (CB3) genomes were subcloned into T7/SP6 RNA transcription vectors. In vitro transcribed RNA from the T7 promoter detected their respective HAV or CB3 genomic RNA. Conversely, SP6 transcripts detected viral negative-stranded RNA but not the genome. When both ssRNA probes were tested at high temperature (65 degrees C), they did not hybridize with intracellular RNAs from 6 primate cell cultures used for isolation of HAV and other enteroviruses. The HAV probe did not hybridize with 13 different enteroviruses but detected as little as 500-1000 infectious units of the 7 strains of HAV tested. Conversely, the CB3 probe showed strong homology with all 13 enteroviruses tested but not HAV. The probes were used to detect HAV and other enteroviruses in water samples after virus amplification in cell culture. HAV was detected in water samples obtained during a waterborne hepatitis outbreak using the ssRNA probe. These samples were negative for HAV by direct solid phase radioimmunoassay and were not positive by immunoassays of inoculated cell cultures until several weeks of propagation. The CB3 ssRNA probe detected enteroviruses in samples of surface water and drinking water that were negative for cytopathic effects in inoculated cell cultures.

Animals↗
PubMed1991

99mTc-anti-CEA radioimmunoscintigraphy of lung adenocarcinoma.

Anti-carcinoembryonic antigen radioimmunoscintigraphy (anti-CEA RIS) in colorectal adenocarcinoma has been reported to allow a better estimation of the local tumor extension than other radiologic methods. This study evaluated the clinical feasibility of a 99mTc-labeled anti-CEA monoclonal antibody (BW 431/26, Behring Institute, FRG) in 11 patients for staging of primary adenocarcinoma of the lung. The primary tumor size ranged from 3 to 8 cm with a mean of 4 cm. Mediastinal and hilar nodes were present in four patients, intrapulmonary metastases were present in two patients, and pleural and liver metastases were present in one patient each. The CEA levels were in the range of 2 to 265 ng/ml and elevated (greater than 5 ng/ml) in six patients. Planar scintigraphy was performed at 6 h and 24 h post injection (pi). Analog and digitized images were interpreted by two observers. One patient was imaged twice and experienced serum sickness due to human anti-mouse antibodies (HAMA) after the second study, which showed marked unspecific tracer uptake in liver, spleen, and bone marrow, but no specific uptake by the tumor and was excluded from further analysis. Visual interpretation identified the primary tumor clearly in seven patients. No tumor imaging was observed in two patients. Two patients were classified as having questionable imaging due to a poor separation of tumor uptake from mediastinal blood pool. The primary tumor could be clearly delineated in both patients after comparison with the chest radiograph. Thus, the overall sensitivity for imaging of the primary tumor was 82 percent. The average target/background ratio was 1.31 +/- 0.17:1 at 6 h pi, and 1.30 +/- 0.16:1 at 24 h pi. Hilar and mediastinal nodes were correctly suspected in three patients, but the cardiac blood pool hampered a clear interpretation. Intrapulmonary and pleural metastases were diagnosed in all cases. The single liver metastasis was missed because of the high unspecific tracer uptake. Planar anti-CEA RIS with 99mTc BW 431/26 was superior to computed tomography (CT) in one case with subtotal tumor resection. We summarize that at present, planar anti-CEA RIS with 99mTc BW 431/26 cannot be advised as a routine staging procedure in adenocarcinoma of the lung, but it may be helpful in the detection of residual or recurrent tumor tissue.

Adenocarcinoma↗
PubMed1991

Duplex Doppler sonography in renal parenchymal disease. Histopathologic correlation.

To evaluate the histopathologic changes influencing Doppler measurements of the resistive index (RI) in renal arteries in renal parenchymal diseases, 68 kidneys in 34 consecutive patients with various forms of renal parenchymal diseases were studied by duplex Doppler ultrasound (duplex US) immediately before percutaneous renal biopsy. The RI, renal length, and renal cortical echogenicity were correlated with the amount of glomerular, interstitial, and vascular changes graded on a scale from 0 to 100. The renal vascular resistance and therefore the RI are significantly correlated with the prevalence of arteriolosclerosis, glomerular sclerosis, arteriosclerosis, edema, and focal interstitial fibrosis. There was no significant difference of the RI in five groups of different renal parenchymal diseases. Of 34 patients, 24 presented with an RI less than 0.7, which was thought to be within the normal range so far. Additionally, the RI increases as the patient's age increases, due to higher incidence of arteriosclerosis. Of our patients, 44% presented with normal cortical echogenicity. Quantitative duplex US using the RI does not reliably distinguish different types of renal medical disorders.

Adult↗
PubMed1990

[Psychological symptoms in school children. An epidemiologic study].

After a study of almost complete patient populations at selected child and adolescent psychiatric facilities as part of the federal government's "Modellprogramm Psychiatrie", two groups of children were investigated with the Child Behavior Checklist: a representative sample of 1969 school children between 6 and 17 years of age and 404 patients from child and adolescent psychiatric services. The presence of psychiatric problems was based on symptoms reported by the parents that experts rated as requiring treatment (at least two critical items). Of the 1969 school children, 253 (12.7%) required counseling or treatment, but only 64 (3.3%) were being treated for psychiatric problems or a developmental delay, half of them at non-psychiatric medical facilities. Symptoms prevalence correlated with age, social class, type of school and nationality.

Adolescent↗
PubMed1990

[Concept and services provided by a mobile pediatric and adolescent psychiatric service in a rural area].

A mobile child and youth psychiatric service is presented that concerned with the mental health care of a county with a population of 239,000 inhabitants. This kind of service was conceived especially to meet the demands of rural regions which are high, as empirical investigations about administrative and real prevalence have shown. The hypothesis that child and youth psychiatric or other specialized institutions create demands not normally existing, could be refuted. The service proved to be an efficient model for mental health care in rural regions so that it can be looked upon--especially in areas which are not sufficiently provided with child psychiatric institutions--as a fully valid alternative to other kinds of mental health services. Still, there is the problem of financing, which is not yet completely solved. A standardized regulation for the whole Federal Republic is suggested with the participation of the health insurance funds.

Adolescent↗
PubMed1989

[Hepatic and splenic abscesses in immunosuppressed patients].

Morphologic characteristics of hepatosplenic abscesses using ultrasound and CT examinations in 13 immunosuppressed patients are presented. Additionally, the results of diagnostic ultrasound and CT guided biopsy procedures (n = 13) are reported. On sonograms, bacterial abscesses were exclusively hypoechoic lesions whereas patients with mycotic abscesses showed additionally target lesions and lesions presenting a "wheels-within-wheels" appearance. Thus, with some limitations, us might help to differentiate between fungal and bacterial abscesses. On CT, all patients presented uniformly with hypodense lesions. Follow-up ultrasound studies showed these abscesses over periods as long as 24 months; biopsy proved some of these as fibrotic lesions without vital bacteria or fungi.

Abscess↗
PubMed1988

[Fibropolycystic diseases of the liver and bile ducts--a case report and review of the literature].

A case of congenital cystic dilatation of the intrahepatic bile ducts (Caroli's disease) is reported. This 20-year-old patient presented also with congenital hepatic fibrosis, fusiform dilatation of the common bile duct and cysts of the liver parenchyma, accompanied by medullary sponge kidneys. The dominant clinical feature was recurrent septic cholangitis. Clinical picture, as well as the diagnostic and therapeutic problems of the individual entities of hepatobiliary fibropolycystic disease are discussed. Although these belong to a family of closely related malformations, whereby involvement of different anatomic levels varies from case to case, such a complex combination as in this patient has not, to our knowledge, been reported before.

Adult↗
PubMed1988

Fluorophore-labeled ether lipids: substrates for enzymes of the platelet-activating factor cycle in peritoneal polymorphonuclear leukocytes.

Cell-free preparations of ionophore-stimulated peritoneal rat polymorphonuclear neutrophils (PMNs) incubated with 1-(N-dansyl-11-amino-1-undecyl)-sn-glycerol-3-phosphorylcholine (dansyllyso-PAF) converted this fluorescent lyso ether lipid into two different classes of products. In the absence of acetyl-CoA 1-(N-dansyl-11-amino-1-undecyl)-2-long chain acyl-sn-glycerol-3-phosphorylcholine (dansylalkyl-2-acyl-GPC) was the only identified new fluorescent phospholipid. In the presence of acetyl-CoA an additional new product, 1-(N-dansyl-11-amino-1-undecyl)-2-acetyl-sn-glycerol-3-phosphorylcholine (dansyl-PAF), was formed. The formation of dansyl-PAF in PMN homogenates was only transient with a maximum after about 4 min. When PMN homogenates were incubated with dansyl-PAF the formation of dansyllyso-PAF was observed prior to the formation of dansyl-2-acyl-GPC. Thus, our data indicate that enzymatically formed dansyl-PAF is completely remodeled into dansylalkyl-2-acyl-GPC by the sequential action of PAF acetylhydrolase and CoA-independent transacylase. These results demonstrate that peritoneal rat PMNs contain lyso-PAF acetyltransferase, PAF acetylhydrolase, and CoA-independent transacylase and that fluorophore-labeled ether lipids provide an easy means to assay enzymes which catalyze important enzymatic reactions involved in the biosynthesis and remodeling of platelet-activating factor.

Animals↗
PubMed1988

Functional asplenia after bone marrow transplantation. A late complication related to extensive chronic graft-versus-host disease.

STUDY OBJECTIVE: To evaluate splenic function in bone marrow transplant recipients, with relation to chronic graft-versus-host disease and infections. DESIGN: Survey, outpatients geographically accessible for voluntary participation. SETTING: Bone marrow transplantation referral center. PATIENTS: Fifteen bone marrow graft recipients (13 allogeneic, 2 autologous), out of a total of 33 patients who received transplants at the center and survived more than 6 months after grafting. MEASUREMENTS AND MAIN RESULTS: In 6 of 15 patients impaired splenic function (functional asplenia) was indicated by the presence of Howell-Jolly bodies in peripheral blood smears, reduced spleen size (P less than 0.001), higher platelet counts (P less than 0.01), higher indium-111 labeled autologous platelet recovery (P less than 0.005), reduced splenic blood flow (P less than 0.001), and reduced accumulation of radioactivity at the splenic site (P less than 0.001). All patients with functional asplenia but only 2 patients without functional asplenia had extensive chronic graft-versus-host disease. The incidence of bacterial infections was four times higher in patients with impaired splenic function. CONCLUSIONS: Functional asplenia is a late complication after allogeneic bone marrow transplantation and contributes to the high susceptibility to bacterial infections in patients with extensive chronic graft-versus-host disease.

Adolescent↗
PubMed1988

[Minimal brain dysfunction--on the revision of a clinical concept. Clinical data of a total pediatric and adolescent psychiatric patient population].

After a discussion of the changes of the MCD concept over the years, the authors describe their own investigation of a total sample of 3280 children, attending outpatient and inpatient facilities of three counties with a total population of 574,000 inhabitants. The aim of the study was to investigate the frequency, sex distribution, and social class dependency of the MCD-diagnosis and its relationship to clinical-psychiatric syndromes. The following results were obtained: There is a strong correlation of MCD-diagnosis with age, sex, and social class. MCD was most frequently diagnosed in the age groups of 3-6, 6-9 and 9-12 years, being twice as frequent in boys than in girls and dominating among the lower social classes. The frequency of MCD in the total sample was 11%, taking into consideration all age-classes. MCD was significantly associated only with two psychiatric syndromes: conduct disorders and hyperkinetic syndrome. There was no correlation with emotional disorders or neurosis, however, a very strong one with specific delays in development, defined according to the multiaxial classification system. 72% of the children diagnosed as MCD-children revealed specific delays in development. But this high correlation was caused only by two conditions: developmental speech/language disorders and specific motor retardation. There was no correlation between MCD and specific reading retardation nor with other specific learning difficulties or mixed developmental disorders. Future research in this field should look upon the so-called MCD more in terms of general developmental delays than in terms of brain pathology.

Achievement↗
PubMed1988

[Ultrasound in terminal renal failure--etiologic conclusions?].

Using standard real time sonography, renal cortical echogenicity, renal length, intrarenal cystic structures and renal calculi were evaluated in 63 patients (30 men, 33 women) in end-stage renal parenchymal diseases (glomerulonephritis n = 21, diabetic glomerulosclerosis n = 9, analgesic nephropathy n = 14, chronic atrophic pyelonephritis n = 19). Patients with glomerulonephritis and diabetic glomerulosclerosis presented with larger kidneys and only slightly increased cortical echogenicity as compared to analgesic nephropathy and chronic atrophic pyelonephritis. In addition, intrarenal cystic structures were found in 50% of the patients with analgesic nephropathy and in 31% of the patients with pyelonephritis, compared with only 14% and 11% in patients with glomerulonephritis and diabetic glomerulosclerosis, respectively. Intrarenal calcifications were more frequent in pyelonephritis and analgesic nephropathy. In end-stage renal parenchymal disease, sonography might be able to distinguish between different types of renal medical disorders.

Adult↗
PubMed1988

Nitrendipine in patients with end-stage renal disease and hypertension.

Calcium antagonists reduce the calcium uptake in vascular cells. The reduction of intracellular calcium leads to vasodilatation and lowering of the blood pressure. The cardiac output is increased, for example, by nitrendipine and related agents, so that the supply of blood to essential organs is improved. Despite the blood pressure decrease, the plasma renin activity increases only slightly and the plasma aldosterone concentration not at all after administration of nitrendipine. The effects of nitrendipine were examined in a study carried out over a period of 6 months on 10 patients suffering from renal hypertension and end-stage renal disease requiring compulsory dialysis. In all patients, adequate blood pressure control was achieved with, in some cases, low doses of nitrendipine combined with other antihypertensive medication. Nitrendipine was very well tolerated, and no side effects were observed.

Adult↗