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Biomedical subjects

R Winter

Publications and source records attributed to R Winter.

At least 199 records · Page 11Linked to original sources
PubMed1993

[Resorbable implant materials in retinal detachment surgery. Initial animal experiment studies].

In detachment surgery after a mechanically stabile chorioretinal scar is at present full scleral indentation no longer mandatory. Following these considerations absorbable scleral implants have been developed and tested in an animal model. Cylindrical pieces of absorbable composite-material with a diameter of 5 mm were sutured as radial scleral explants in 18 rabbits. The composite material consisted of a polyglactin-polydioxanon ratio 7:1. The absorption time for polyglactin is 60 days, for polydioxanon 180 days. The explants produced initially in ultrasonographically measured buckle height between 3.2 and 4.0 mm. The clinical and ultrasonographical follow up study demonstrated a continuous decrease of buckle height. Two weeks after implantation there was a medium height of 2.0 mm after five weeks a medium elevation of 0.5 mm was found. Histopathological examinations showed incidence of a slight resorptive inflammation in the area of the buckle which was not evident after 12 weeks. No scleral infiltration or scleral thinning was found. The promising results have justified controlled clinical trials with the absorbable material which might allow to combine the advantages of silicone sponge explants (precise localization) with those of scleral buckles by inflatible balloons (reversibility).

Absorption↗
PubMed1993

[Quality control in the corneal bank--a necessary measure?].

BACKGROUND: During a period of 3 months 20% of patients who received a corneal transplant showed a prolonged postoperative swelling, of the stroma and an increased number of folds in the epithelium was prolonged. These findings were atypical because there were no complications during the operation and the preoperative examination of the donor cornea showed a normal corneal endothelium. All donor corneas were stored in organ culture before transplantation using minimal essential medium supplemented with 2% fetal calf serum (FCS). This method has been used in the university eye clinic of Hamburg since 1981. In order to establish any correlation between the used organ culture conditions and the clinical findings the different components of the culture medium were checked. We noticed that the serum batch used for organ preservation had been changed at the beginning of the above mentioned period. PATIENTS: From April 20th to June 23rd, 28 penetrating keratoplasties were performed at the department of ophthalmology of the University Clinic of Hamburg. No complications during the surgical procedure or postoperative infection were detectable. Four weeks after transplantation all transplants showed a normal swelling. METHODS: The quality of media or sera is not guaranteed by the company where the substances were purchased. We performed clonal growth assays using human or porcine corneal endothelial cells to evaluate the quality of different charges of fetal calf serum. RESULTS: It could be demonstrated that the acticity of the serum charge used for organ preservation during the described period had a significantly reduced activity in a clonal growth assay compared with various FCS-charges from different companies. CONCLUSIONS: After changing the serum batch the problems described above disappeared. We conclude that quality testing of all supplements of the organ culture medium is necessary in a cornea bank to guarantee a reliable standard of corneal preservation. A clonal growth assay is a sensitive test which is suggested to be useful for quality testing.

Adolescent↗
PubMed1992

Chronic hypoxia changes the ratio of endothelin to ATP release from rat aortic endothelial cells exposed to high flow.

Endothelial cells isolated from the thoracic aorta of normoxic and chronically hypoxic rats were perfused (0.5 ml min-1) and stimulated by increased flow rate (3.0 ml min-1). The release of ATP, endothelin and vasopressin was investigated. During periods of high flow rate, endothelial cells isolated from normoxic rats increased their release of ATP and endothelin. In comparison, in hypoxic rats, ATP release during the period of high flow rate was less, whereas endothelin release was greater. Vasopressin release was not increased during periods of stimulation in either group of animals. These results suggest that, under conditions of reduced arterial oxygen tension, a dynamic balance between ATP and endothelin release could regulate the response of vessels to shear stress.

Adenosine Triphosphate↗
PubMed1992

The effect of selective decontamination of the digestive tract on gastrointestinal enterococcal colonization in ITU patients.

OBJECTIVE: The effect of selective decontamination of the digestive tract (SDD) on Intensive Therapy Unit (ITU)-acquired enterococcal infection and colonization was studied. Changes in the predominant species isolated and resistance patterns to antimicrobial agents were also studied. DESIGN: Three groups were investigated: historical control (HC), contemporaneous control (CC) and patients receiving SDD (topical polymyxin, amphotericin B and tobramycin throughout ITU stay with intravenous ceftazidime for the first 3 days only). SETTING: Adult general ITU with 7 beds. PATIENTS: Patients with a nasogastric tube in situ and who were likely to remain in ITU for 48 h or longer were recruited. RESULTS: Enterococcal infections occurred in 3 of 84 HC patients and 2 of 91 CC patients. There were no unit-acquired enterococcal infections in the SDD group. There were 140 episodes of enterococcal colonization occurring in 112 patients, with significantly more in the SDD and CC groups (p < 0.05. There were no significant differences in antibiotic sensitivities between the three groups. Enterococcus faecalis was the most frequently isolated species. CONCLUSION: SDD does not predispose to enterococcal infection but does encourage colonization in patients receiving the regimen and other patients in ITU at the same. There is a complex interaction of factors which influence faecal flora and the likelihood of patients becoming colonized or infected with enterococci.

Administration, Buccal↗
PubMed1992

Falling spells associated with antidepressant drug treatment.

Six patients experienced falling spells concurrent with the intake of antidepressant drugs in high doses or in moderate doses combined with other psychotropic drugs. The close temporal correlation between drug ingestion and the falling spells and their immediate termination after reduction or discontinuation of medication suggests that these drugs caused the falls. Further factors predisposing to the falling spells remain to be defined.

Aged↗
PubMed1992

A study of some mechanical properties of an RTV polydimethylsiloxane for extraoral maxillofacial prostheses.

The construction of facial prostheses simulating the missing tissues as closely as possible is an imperative and demanding task. Such prostheses will be comprised of parts presenting different mechanical properties attempting to simulate facial tissues. In this study the mechanical properties of a room temperature vulcanized (RTV) silicone facial elastomer were modified, altering the molecular architecture by controlling the amount of cross-linking. A wide range of compliance was achieved which enables more lifelike facial prostheses to be made in clinical practice.

Cross-Linking Reagents↗
PubMed1992

A controlled trial of selective decontamination of the digestive tract in intensive care and its effect on nosocomial infection.

Nosocomial infection is a major problem in intensive therapy units (ITUs) and a significant cause of mortality. Selective decontamination of the digestive tract (SDD) has been advocated as a means to reduce ITU morbidity and mortality. Ninety-one patients in a general ITU underwent SDD, consisting of topical polymyxin E, tobramycin and amphotericin B administered throughout the unit stay together with parenteral ceftazidime for the first three days, and were compared with 84 historical and 92 contemporaneous control patients who were treated conventionally. Twenty-seven historical and 32 contemporaneous control patients developed unit-acquired infections, in comparison with only three patients in the SDD group (P less than 0.01). Mortality in the SDD group (36%) was not significantly different from that in the other two groups (historical control 40%, contemporaneous control 43%). Screening specimens revealed a significantly higher rate of colonization with resistant Acinetobacter spp. in the contemporaneous control than in the other two groups of patients; infection caused by resistant bacteria did not occur. SDD did not lead to a significant reduction in the use of systemically-administered antibiotics when compared with either control group. SDD may be used selectively in an ITU without ill effects on those patients not receiving SDD; nevertheless, microbiological monitoring is needed to detect emergence of resistant bacteria in the unit.

Adolescent↗
PubMed1992

[Endothelial cell protective effect of high viscosity substances in cataract surgery].

An experimental setting is presented to evaluate the endothelial protection offered by various viscoelastic materials applied in cataract surgery. The substances used were: hydroxypropylmethylcellulosis, a hyaluronic acid preparation (molecular weight 5.10(6), concentration 10 mg/ml), a hyaluronic acid preparation (molecular weight 800 000, concentration: 35 mg/ml), and balanced salt solution as control. The endothelial surface of pig corneas were covered by test substances and spread with a loop of prolene 4.0 suture material in a mechanically standard way. A total of 40 corneas were examined and the amount of endothelial damage evaluated by photometry using Janus-green wash-out, a substance, which selectively binds to damaged endothelial cells or descement membrane. The damaged surfaces differed significantly in all groups of viscoelastic substances and in the control group. Examination showed that the least damage was in group 3, followed by group 1 and the most damage in group 2. Endothelial protection during cataract surgery can be improved by modifications of the substances presently applied.

Animals↗