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Biomedical subjects

R Hahn

Publications and source records attributed to R Hahn.

At least 37 records · Page 2Linked to original sources
PubMed1993

Immuno- and lectin histochemistry of epithelial subtypes and their changes in a radiation-induced lung fibrosis model of the mini pig.

Cell types of lung epithelia of mini pigs have been studied using a panel of monoclonal and polyclonal antibodies against cytokeratins (CKs) and vimentin and three lectins before and after radiation-induced fibrosis. In normal tissues, CK18 specific antibodies reacted above all with type II alveolar epithelial cells, while CK7 and pan CK-specific antibodies stained the whole alveolar epithelium. In bronchial epithelial cells, CKs 7, 8, 18 and focally CKs 4 and 13 as well as vimentin were found. Cell specificity of the CK pattern was confirmed by double label immunofluorescence using type II cell-specific Maclura pomifera (MPA) lectin, type I cell specific Lycopersicon esculentum (LEA) lectin and capillary endothelium-binding Dolichos biflorus (DBA) lectin. In experimental pulmonary fibrosis, enhanced coexpression of CK and vimentin was observed in bronchial epithelium. Subtypes of alveolar epithelial cells were no longer easily distinguishable. CK18 was found to be expressed in the entire alveolar epithelium. The gradual loss of the normal alveolar epithelial marker, as seen by the binding of MPA to type I-like cells, of LEA to type II-like cells and the partial loss of MPA-binding to type II cells, was paralleled by the appearance of CK4, typical for squamous epithelia, and the occurrence of DBA-binding in epithelial cells. Implications of these results for general concepts of intermediate filament protein expression and lectin binding in the fibrotic process are discussed.

Animals↗
PubMed1993

Microbial accumulation and vitality on different restorative materials.

A new technique using standardized test facings was designed to evaluate interdental plaque accumulation on different restoration materials. In 10 volunteers, a total of 40 samples, including enamel, two different ceramics and a bonding composite, were inserted one by one into a precision attachment in an experimental inlay bordering on either the lower second premolar or the lower first molar. Bacterial accumulation on each approximal specimen was allowed to mature for 3 d. Following microbiological processing of the plaque samples, total bacterial counts, colony forming units and the bacterial vitality were determined. The results revealed different accumulation rate patterns. Both ceramics accumulated less plaque with a reduced vitality compared to enamel, while the bonding composite showed no significant differences compared to the natural tooth substance. No significant differences were detected when comparing the two examined ceramics.

Adult↗
PubMed1993

A three-generational presentation of separation anxiety in childhood with agoraphobia in adulthood.

School phobia belongs to a family of childhood anxiety states that appear to be related to adult forms of anxiety disorders, particularly to panic disorder with agoraphobia. School phobia appears to affect at least 5 percent of elementary school children and 2 percent of middle school children. Many of these children would be classified under the current DSM-III-R system of nomenclature as suffering from separation anxiety disorder. The present study is related to the elaboration of a three-generation family presentation of separation anxiety disorder manifesting itself as school phobia in childhood, which evolves toward panic disorder with agoraphobia in young adulthood and diffuse anxiety with hypochondriacal features in later life. All 13 genetically related members of the family investigated have been afflicted. The children with separation anxiety disorder and school phobia in this family who have been treated with imipramine have shown a resolution of anxiety symptoms that has allowed their successful return to school. The information from this family would fit into a model that describes a spectrum of anxiety disorders that present with different manifestations of overt psychopathology throughout the life cycle. We hope to follow this family prospectively over the next 30 years.

Adolescent↗
PubMed1993

Microstructure and strength analysis of ultrasonically shaped ceramics.

In this study, the influence of a new ultrasonic shaping procedure on the surface quality, microstructure, bending strength and fatigue behaviour of a feldspathic porcelain was investigated. A total of 120 standardized (ISO 6872) autoglazed, ground, lapped and ultrasonically machined porcelain test bars were analyzed. Another 24 equiformat experimental alumina ceramics, which were ultrasonically machined, as well as 24 nontreated fload glass specimen served as controls. It could be shown that the porcelain removal process with diamond grinding wheels yielded a rough surface microrelief and lead to structural subsurface damage, decreasing bending strength and fatigue behaviour. In contrast, ultrasonic shaping resulted in a smoother surface and prevented damage to the subsurface layer of the machined brittle porcelain, although, the smoothest surfaces were achieved by lapping. Both bending strength and fatigue behaviour of the conventional dental porcelain were increased by ultrasonic machining. However, the fracture toughness of the experimental alumina was substantially higher and was not subjected to a decrease in fatigue.

Aluminum Oxide↗
PubMed1993

[A comparison of different endotracheal tubes. Tracheal cuff seal, peak centering and the incidence of postoperative sore throat].

UNLABELLED: The study objective was to evaluate cuff seal, tube tip position and incidence of postoperative sore throat in three different endotracheal tubes: the reusable Rüsch "red rubber" tube (low-volume, high-pressure cuff) and the disposable Rüsch "Super Safety Clear" and Mallinckrodt "lo-pro" tubes (both high-volume, low-pressure cuffs). METHODS: In a prospective randomized trial, 150 consecutive patients scheduled for minor orthopaedic surgery under standardized general anaesthesia, including standardized cuff pressure control, were allocated to one of the three types of endotracheal tube. Leakage and intratracheal tube tip position were investigated by means of fiberoptic tracheoscopy via the endotracheal tube, preceded by pharyngeal instillation of indigocarmine. The semi-standardized interviews for the recording of postoperative sore throat were performed once a day under double-blind conditions from the day of operation to postoperative day 3. Statistical independence testing was based on the chi 2-test, significance was assumed at P < 0.05. MAIN RESULTS: A past-cuff leakage of the pharyngeally instilled dye was found in three patients with "red rubber" tubes. In all of these cases the tracheal cross section deviated markedly from circular. The tips of the "Super Safety Clear" tubes tended to be better centred (P = 0.099). Bad tip position, however, had little influence on postoperative throat complaints (P = 0.394). The differences in incidence of postoperative throat complaints between the "red rubber" (48.9%), "Super Safety Clear" (35.6%) and "lo-pro" tubes (34.1%) did not reach the 5% level (P = 0.288). Such complaints, however, were significantly more frequent in females and in obese patients who exceeded their Broca weights by more than 25%. By contrast, postoperative throat complaints did not vary statistically significantly by age group, tracheal cross-sectional shape, use of atropine or duration of intubation. CONCLUSION: Despite the economic (usable up to 100 times) and ecological (less PVC waste) advantages of the rubber tube, the disposable tubes with high-volume, low-pressure cuffs tended to be superior regarding cuff seal, tube tip position and incidence of postoperative throat complaints. Nevertheless, the continued use of "red rubber" type reusable tubes may be justified in cases where the tube has to stay in place for only a short time.

Adult↗
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↗