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Biomedical subjects

R Hahn

Publications and source records attributed to R Hahn.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1988

Changes in intravesical pressure during irrigating fluid absorption in transurethral prostatic surgery.

Continuous recording of intravesical pressure (IVP) and incremental volumetric measurements of irrigating fluid absorption were performed during 37 transurethral resections of the prostate (TUR). Absorption which resulted in concomitant dilutional changes in peripheral blood, indicating intravascular absorption, was associated with prolongation of the time required to increase the IVP. There was an inverse relation between the change in maximum IVP and the rate of irrigating fluid absorption. Absorption that did not result in concomitant dilutional changes in peripheral blood, indicating extravascular absorption, was associated with similar changes in IVP parameters but the critical pressure for absorption was lower.

Absorption↗
PubMed1988

Irrigating fluid absorption and blood loss during transurethral resection of the prostate studied with a regular interval monitoring (RIM) method.

A method for the study of physiological events during transurethral resection of the prostate (TUR) is described. Measurements of volumetric irrigating fluid balance, blood loss, central venous pressure (CVP) as well as blood haemoglobin and serum levels of sodium and glycine were performed at 10-min intervals. This regular interval monitoring (RIM) method offers the possibility to retrospectively correlate changes that occur during TUR at discrete time intervals. In 20 patients undergoing TUR, irrigating fluid absorption occurred throughout the procedure although the risk of having an absorption increased 30 min after surgery commenced. Increase of blood loss coincided with intravascular but not with extravascular absorptions. If there was a rapid massive intravascular absorption of about 500 ml/10 min, the CVP increased greater than 2 mmHg. The total intraoperative blood loss was not greater in patients with large absorption volumes. RIM will detect absorption greater than the urine excretion in any given period of time. If absorption occurs during a limited time of the TUR, RIM allows a partial correction for the urinary excretion in the volumetric fluid balance.

Absorption↗
PubMed1988

Neuroleptic plasma concentrations and clinical response: in search of a therapeutic window.

There is much interest in finding a therapeutic window for commonly used neuroleptics so that dosage can be individualized and side effects minimized. The authors review specific requirements of good study design and survey the literature that has investigated the relationship between therapeutic response and plasma concentrations of neuroleptics. The evidence from a number of fixed-dose haloperidol studies suggests, but does not yet prove, the existence of a therapeutic window for this compound.

Antipsychotic Agents↗
PubMed1988

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Dental Implantation, Endosseous↗