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Biomedical subjects

R Hahn

Publications and source records attributed to R Hahn.

At least 19 recordsLinked to original sources
PubMed1992

Amino acid concentrations in plasma and skeletal muscle after transurethral resection syndrome.

The concentrations of amino acids in plasma and skeletal muscle were measured 1 and 4 hours after transurethral prostatic resection in three patients who developed symptoms of the transurethral resection syndrome. The irrigating solution contained 1.5% of glycine and 1% of ethanol. The concentrations of glycine in plasma and muscle were equal within an hour of the operation, and at four hours the abnormally high glycine concentration persisted in muscle, though it had decreased rapidly in plasma. Our data suggest that skeletal muscle is a quantitatively important reservoir for glycine when this amino acid is supplied in potentially toxic amounts, but that the plasma glycine concentration returns to normal as the patient's clinical condition improves.

Acid-Base Equilibrium↗
PubMed1991

Absorption of irrigating fluid during transurethral prostatic resection as measured by ethanol, radioisotopes, and regular-interval monitoring.

Ethanol monitoring is a novel noninvasive method for immediate detection of absorption of irrigating fluid during transurethral prostatic resection. Its accuracy was evaluated during thirteen resections using 5% mannitol +2% ethanol as the irrigating fluid. The ethanol concentration in the expired breath correlated strongly with the degree of absorption of intravascular irrigating fluid as determined by a radioisotope technique, and fluid volume measurements, and with the changes in the serum sodium concentration. Extravascular absorption of the irrigating fluid resulted in prolonged elevation of the ethanol concentration and gave smaller changes in the serum sodium concentration.

Absorption↗
PubMed1991

Comparison of chlorambucil and prednisone versus cyclophosphamide, vincristine, and prednisone as initial treatment for chronic lymphocytic leukemia: long-term follow-up of an Eastern Cooperative Oncology Group randomized clinical trial.

The Eastern Cooperative Oncology Group (ECOG) conducted a study in which patients with advanced chronic lymphocytic leukemia (CLL) were randomized between a regimen consisting of chlorambucil (30 mg/m2 orally day 1) and prednisone (80 mg orally days 1 to 5) (C + P) administered every 2 weeks and a more intensive regimen of cyclosphosphamide (300 mg/m2 orally days 1 to 5), vincristine (1.4 mg/m2 intravenously [IV] day 1), and prednisone (100 mg/m2 orally days 1 to 5) (CVP) given every 3 weeks. Treatment was continued for up to 18 months to maximal response. Of the 122 eligible patients, 60 received C + P, while 62 received CVP. With a median follow-up of 7 years, there were no significant differences in survival (4.8 v 3.9 years, P = .12), complete remission (CR) rate (25% v 23%; P = .83), or duration of response (2.0 v 1.9 years; P = .78) between C + P and CVP. Toxicity was modest despite the prolonged treatment. The long median survival of 4.1 years for stage III and IV patients is superior to that usually reported. This could stem from continuing treatment to maximal response rather than an increase in intensity of therapy. These results are comparable to those reported with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) therapy by other investigators. The data suggest that intermittent C + P administered to maximal response continues to be the standard treatment approach for advanced CLL.

Adult↗
PubMed1990

[Field studies of the effect of sperm motility and morphology on the fertility of boars used for insemination].

Based on 2127 first services in a field trial, the influence of sperm motility and morphology on the fertility of ten AI boars was investigated using semen stored for three and five days. Depending on sperm morphology the farrowing rate differed by up to 31% and the litter size differed by up to 3.4 piglets. Sperm motility and morphology are useful parameters in selecting sires for AI, especially in the case of inseminations with semen stored long-term.

Animals↗
PubMed1990

[Experimental studies on the reproducible precision of fit of ceramic inlays].

Three different types of ceramic inlay materials (Dicor, Biodent-Inlay-Keramik, Cerec) were evaluated for precision of reproduction and dimensional fit. The findings of this study revealed that laboratory-made restorations displayed satisfactory characteristics of reproduction except for the edges. Furthermore the initial fit of these materials was comparable to the fit of gold restorations. The Cerec-inlay system by contrast displayed insufficient reproduction characteristics especially at lines, angles and edges. The average marginal gap of Cerec inlays measured was 154 microns. General guidelines for cavity preparations based on the present findings are discussed.

Ceramics↗
PubMed1989

Effects of isosmotic and hyperosmotic glycine solutions on the fluid balance in conscious sheep.

Glycine 0.55 g.kg-1 was given as an isosmotic (285 mosmol.kg-1) and a hyperosmotic (approx. 3,000 mosmol.kg-1) solution by intravenous infusion during 30 min to six euhydrated ewes. Urine and blood samples were collected, and the distribution of the administered water between the intra- and extracellular fluids (ICF and ECF) was calculated for up to 150 min after the infusions. Both solutions produced an osmotic diuresis with a marked increase of the urinary excretion of sodium, potassium, and amino acids. A paradoxical increase of the plasma vasopressin concentration occurred from the isosmotic but not from the hyperosmotic glycine solution. At the end of the follow-up period, the isosmotic glycine solution had resulted in hyperhydration of the ICF and the hyperosmotic solution in dehydration of the ICF, whereas with both fluids, the ECF resumed the same volume as before the experiments.

Amino Acids↗
PubMed1989

Immediate detection of irrigant absorption during transurethral prostatectomy: case report.

A transurethral prostatic resection is described in which immediate detection of a rapid massive irrigant absorption could be made by the use of ethanol-tagged irrigating fluid and repeated measurements of the ethanol concentration in the patient's expired breath. This monitoring enabled the surgeon to prevent further absorption by concluding the operation before symptoms resulted. Furosemide was given immediately to promote renal excretion of the absorbed irrigant, and the intravenous infusions were temporarily restricted to limit the intravascular fluid load. In retrospect, volumetric measurement showed that a total of 2410 ml of irrigant had been absorbed.

Absorption↗
PubMed1989

Effect of placement of occlusive membranes on root resorption and bone regeneration during healing of circumferential periodontal defects in dogs.

Previous studies indicate that root resorption is a frequent sequela to significant amounts of periodontal repair in animal models. A model was developed in labrador dogs to study periodontal wound healing in large circumferential defects in the absence of influence from the oral environment. A polytetrafluorethylene membrane of 1 micron pore size (GORE-TEX) was used to occlude cells from specific tissues from populating the healing dentin-connective tissue wound. 3 modalities were studied: (1) control, in which no membrane and therefore no cell occlusion was used, (2) flap occlusion, in which the internal surface of the flap was lined with the membrane preventing contribution of cells from the flap, (3) bone occlusion, in which the reduced alveolar bone was lined with the membrane preventing contribution from bone cells. Wound closure included total submergence of teeth and membranes. The membranes remained incorporated and no exposure of membranes or teeth occurred during the 3 months healing period. Histology revealed bone regrowth in all 3 treatment modalities. It is suggested that inductive elements in the connective tissue or dentin, or bone cells from periosteum were responsible for bone regrowth in the bone membrane treatment modality. No significant difference was seen for root resorption between the 3 treatment modalities. This study found that physical occlusion of cells from the inside of the surgical flap, or from the pre-existing bone, is not sufficient to prevent root resorption in periodontal wound healing.

Alveolar Process↗
PubMed1989

Viscoelasticity and red blood cell aggregation in patients with coronary heart disease.

Viscoelastic parameters were evaluated in 169 consecutive male patients with clinical signs of coronary heart disease. The patients were classified according to the extent of coronary artery stenosis. Levels of blood viscosity, erythrocyte aggregation, and plasma viscosity were elevated in patients with extensive coronary vessel disease. However, the differences between the several groups were not statistically significant. The increase of hemorheologic parameters was mainly due to high hematocrit, fibrinogen, and cholesterol concentrations. There was a significant correlation between plasma fibrinogen values and plasma viscosity levels. Blood viscosity and erythrocyte aggregation can be described by multiple linear regression as a function of the sum of log hematocrit, fibrinogen, cholesterol, and alpha 2-macroglobulin.

Blood Viscosity↗
PubMed1989

Combination chemotherapy versus single agents followed by combination chemotherapy in stage IV non-small-cell lung cancer: a study of the Eastern Cooperative Oncology Group.

During the last decade, the Eastern Cooperative Oncology Group (ECOG) has studied a series of combination chemotherapy regimens in metastatic (stage IV) non-small-cell lung cancer (NSCLC). In January 1984, the ECOG activated a randomized study, EST 1583, which concluded the evaluation of combination regimens in phase III trials and initiated the evaluation of single agents exclusively in previously untreated patients. The treatment regimens in EST 1583 consisted of: (1) mitomycin, vinblastine, and cisplatin (MVP); (2) vinblastine and cisplatin (VP); (3) MVP alternating with the regimen cyclophosphamide, doxorubicin, methotrexate, and procarbazine (CAMP); (4) carboplatin followed by the MVP regimen at the time of progression; and (5) iproplatin followed by MVP at the time of progression. From January 1984 to July 1985, 743 patients were entered on this trial and 699 fulfilled the eligibility requirements. The following objective response rates (complete plus partial remissions) were observed: first-line MVP, 20%; VP, 13%; MVP/CAMP, 13%; carboplatin, 9%; iproplatin, 6%; and second-line MVP, 6%. First-line MVP produced a significantly higher response rate than the other treatments (P = .03) adjusted for prognostic variables. Using analyses that were adjusted for prognostic covariates, survival for patients treated on a given regimen was compared with survival for all remaining patients. These analyses showed that treatment with carboplatin was associated with longer survival (median survival time, 31.7 weeks; P = .008) while initial treatment with MVP was associated with a trend for shorter survival (median survival time, 22.7 weeks; P = .09). It should be noted that none of these regimens appear to have produced a clinically meaningful prolongation of survival. Similar analyses evaluating time to progression disclosed that carboplatin-treated patients had a significantly longer time to progression (median time to progression, 29 weeks) than all remaining patients (P = .01). Life-threatening and lethal toxicities (toxicity grades 4 and 5) were greater on the combination regimens than on the single agents (P less than .0001). Based on these results, current group-wide ECOG trials in stage IV NSCLC consist of randomized phase II trials evaluating single agents.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Ultrasound for the primary care physician. Applications in family-centered obstetrics.

Ultrasound imaging is a noninvasive diagnostic tool that enhances the patient's and physician's understanding of prenatal care. According to a multisite study, use of ultrasound by primary care physicians appears to improve prenatal patient education and support early formation of the family unit. Other potential benefits include early detection of fetal abnormalities, savings in time and cost, and enhanced continuity of care. However, consultation with and referral to specialists, when appropriate, remain essential ingredients for state-of-the-art healthcare. Further studies defining the role and boundaries of ultrasound in primary care are needed.

Adult↗