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Biomedical subjects

M Winter

Publications and source records attributed to M Winter.

225 records · Page 13Linked to original sources
PubMedDate not supplied

[Experimental results of stepped titanium shafts for hip endoprostheses].

Among the materials which can be used for hip prostheses to be implanted without bone cement, ceramics and titanium possess the best overall properties for insuring long-term stability in the light of present knowledge. However, considered separately, the two materials are most suitable for different special requirements. Results of long-term animal experiments conducted by different working groups on functionally stressed hip and tooth-root implants made of bio-inert Al2O3 ceramic and titanium have furnished knowledge of the possibilities and limitations of the adaptation reaction of the bone tissue. The present authors investigated whether, by combining Al2O3 ceramic and titanium, a cement-free total hip replacement can be adapted to specific local stresses, taking biomechanical rules and anatomical factors into account. In recent experimental series it proved possible to limit the problems which had occurred in previous series, reported elsewhere. Positive results in dogs led to a human implant which has so far been used 15 times, with Al2O3 (FRIALIT) acetabula and heads, which have been implanted successfully for a number of years, in combination with the new stepped titanium shaft. In addition to a short review of follow-up findings thus far, the results of the experimental investigations are presented.

Animals↗
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Histopathological comparison of photorefractive keratectomy and laser in situ keratomileusis in rabbits.

BACKGROUND: After 193 nm excimer laser photorefractive keratectomy (PRK) for myopia, superficial opacities in the ablation zone and regression of refractive results can occur. Clinical studies have emphasized that corneal clarity and early refractive stability can be achieved with laser in situ keratomileusis (LASIK). We present clinical and histological results that compare PRK and LASIK for the treatment of myopia in rabbits. MATERIALS AND METHODS: We treated 12 New Zealand white rabbits with PRK and 12 with LASIK using a 193-nm excimer laser (Aesculap Meditec). In both techniques, the identical excimer software and ablation parameters of -10 D treatment depth were used. Six months after surgery, all eyes were removed and prepared for light, fluoresence and transmission electron microscopy. RESULTS: At the time of enucleation, nine eyes in the PRK group had a moderate to high degree of haze (grade 2 to 3), whereas after LASIK, all corneas showed an almost clear interface in the ablation zone. Correspondingly, all histological investigations after LASIK showed a regular stromal architecture, in contrast to the obvious anteri or stromal disorganization after PRK. CONCLUSION: The preserved integrity of the superficial corneal layers after LASIK ensures quick wound healing with minimal tissue proliferation, resulting in a transparent corneal interface. This technique appears especially suitable for correcting high myopia.

Animals↗
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Ultrastructural and immunohistochemical findings after linear excimer laser keratectomy.

BACKGROUND: One human pathology specimen has been studied previously following the use of the excimer laser for the correction of astigmatism. We report histopathologic findings following linear corneal excisions with the excimer laser. METHODS: A 193 nm excimer laser was used to create symmetrical, transverse excisions in a human eye to correct astigmatism. Three months later, a full-thickness corneal transplant was performed due to unsatisfactory refractive results. The excised corneal button was examined with light microscopy, transmission electron microscopy and immunohistochemistry. RESULTS: An area 10 to 20-micron wide was observed between the epithelial cells within the keratectomy and the sharply dissected stromal lamellae. This area stained positive for laminin and pro-collagen type III. Some epithelial cells showed processes reaching into this area. Descemet's membrane, immediately underneath the area of the keratectomy, contained atypically striated collagen fibers. CONCLUSIONS: These findings demonstrate wound healing changes similar to those reported following diamond knife keratotomy and photorefractive keratectomy for myopia. The changes in the posterior cornea are similar to those previously reported when an excimer laser beam approached Descemet's membrane.

Aged↗
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Bilateral cataract after phakic posterior chamber top hat-style silicone intraocular lens.

BACKGROUND: New strategies have been developed for surgical treatment of high myopia. Recently, implantation of minus power posterior chamber intraocular lenses (IOL) into phakic eyes has been introduced. METHODS: We report a 37 year-old female patient who developed bilateral anterior subcapsular cataract 7 years after minus-power, top hat-style silicone posterior chamber IOL implantation in Russia. The corrected visual acuity was right eye 20/200 and left eye 20/63. Because of the high myopia and the posterior chamber IOL in her phakic eyes, biometry for IOL calculation gave contradictory results. Both posterior chamber IOLs were found to be adherent to the crystalline lenses. After posterior chamber IOL explantation and phacoemulsification, intraoperative retinoscopy was performed. With this aphakic refraction, the IOL power was calculated and implanted. The explanted posterior chamber IOLs were examined by scanning electron microscopy. RESULTS: After bilateral operation the corrected visual acuity increased to right eye 20/32 and left eye 20/40, respectively. On scanning electron microscopy, a membranous structure of unknown origin was noted on the entire surface of the explanted posterior chamber IOLS. CONCLUSION: There is a potential risk of cataract formation after implantation of this top hat-style silicone posterior chamber IOL. If cataract extraction in this specific situation is needed, a different approach for calculating the aphakic IOL power is necessary, such as intraoperative retinoscopy.

Adult↗
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Vaginal vault suspension and enterocele repair by Richardson-Saye laparoscopic technique: description of training technique and results.

OBJECTIVES: To describe the Richardson-Saye technique for laparoscopic vaginal vault suspension and enterocele repair (vaginal apex reconstruction) and the appropriate training needed for performance of this technique. METHODS: Before using this technique, Drs Carter, Winter, and Mendelsohn first received training by observation of skilled surgeons performing the procedure, attending courses, and finally being tutored and proctored by Dr Saye on the appropriate performance of the technique. They then used this technique to surgically treat eight patients, 42 to 85 years of age, mean age 62 years, between March and September of 1999. RESULTS: We included eight patients in this study who underwent the Saye-Richardson vaginal vault suspension and enterocele repair (apical vaginal vault reconstruction) by the suture technique. In all patients at six-month follow-up, the vaginal apex remains intact and well supported. We describe here the entire vaginal vault suspension and enterocele repair procedure with all its relevant details. CONCLUSION: Laparoscopic reconstruction of the disrupted vaginal apex followed by reattachment to the previously broken uterosacral ligament with the use of permanent suture provides a secure and anatomically correct vault suspension. Before performing this technique, physicians should undergo proper training, including observation, courses, tutoring, and proctorship by a surgeon experienced in performing this technique.

Adult↗
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A pilot survey of aquatic activities and related consumption of alcohol, with implications for drowning.

The investigators considered the relationship between participation in aquatic activities and the consumption of alcohol, with their implications for the risk of drowning. In a telephone survey with random-digit dialing, interviewers asked Massachusetts residents ages 20 years and older how often they engaged in various aquatic activities, in what settings, and how often they drank alcohol in connection with participation in aquatic activities. Of 294 respondents, 79 percent of the men and 72 percent of the women reported participating in aquatic activities during August 1988, the month prior to the interview. Respondents were asked to identify their most recent aquatic activity. The mean number of days of participation in the month was 13. The most frequently reported aquatic activities were swimming (76 percent), followed by sunbathing (74 percent), power boating (25 percent), and fishing from shore (15 percent). Among those persons reporting participation in aquatic activities, 55 percent had been at the ocean on the most recent occasion, 26 percent at lakes or ponds, 17 percent at pools, and 2 percent at rivers. Among those persons reporting aquatic activities, 36 percent of the men and 11 percent of the women reported having drunk alcohol on the most recent occasion. Those who reported drinking in aquatic settings were more likely to report driving after drinking than those who did not drive. Implementation of new Federal regulations and State laws concerning drinking and boating should be accompanied by public education on the risks of drowning if aquatic activities and alcohol consumption are combined.

Adult↗
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Lower legal blood alcohol limits for young drivers.

To reduce the involvement of young drivers in alcohol-related crashes, 29 States and the District of Columbia have established lower legal blood alcohol limits for drivers younger than age 21 than for adult drivers. Of these, 12 lowered the legal limit for young people prior to 1991. To assess the impact, these 12 States were paired for comparison with 12 nearby States matched for legal drinking age and timing of changes in that law. Among drivers ages 15-20, fatal crashes involving a single vehicle at night are three times more likely than other fatal crashes to be alcohol-related. Whether the proportion of fatal crashes that involved single vehicles at night declined more among young drivers targeted by lower blood alcohol limits than among young drivers of the same age in comparison States was examined. The maximum available equal number of pre- and post-law years were compared in each pair of States. During the post-law period, the proportion of fatal crashes that involved single vehicles at night declined 16 percent among young drivers targeted by lower blood alcohol laws, whereas it rose 1 percent among drivers of the same age in comparison States where blood alcohol limits were not changed (P < .001). Among adults, the proportion of fatal nocturnal crashes that involved single vehicles declined 5 percent in the group of States with the lowered levels for young people during the period after the law was enacted and 6 percent in the group of neighboring comparison States. The proportion of fatal crashes that involved single vehicles at night declined 22 percent among drivers in States with .00 percent limits, whereas it declined only 2 percent among drivers of the same age in comparison States (P <.003). Among those targeted by .02 percent BAL limits, the proportion of fatal crashes that involved single vehicles at night declined 17 percent. It rose 4 percent in comparison States(P = .005). No significant difference appeared between States that lowered blood alcohol levels to the range of .04-.06 percent relative to comparison States.If all States adopted .00 or .02 percent limits for drivers ages 15-20, at least 375 fatal single vehicle crashes at night would be prevented each year.

Accidents, Traffic↗
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Effects of Maine's 0.05% legal blood alcohol level for drivers with DWI convictions.

OBJECTIVE: To determine whether a Maine law lowering the legal blood alcohol limit (BAL) from 0.10% to 0.05% for people convicted of driving while intoxicated (DWI) reduced the involvement of this group in fatal crashes. METHODS: The authors calculated changes in the proportions of fatal crashes involving drivers with prior DWI convictions from the six-year period before enactment of the law to the six-year period following enactment of the law, comparing Maine with the other New England states. RESULTS: In Maine, the proportion of fetal crashes involving drivers with recorded prior DWI convictions declined 25% following passage of the 0.05% DWI law, while the proportion rose in the rest of New England during the same years. The proportion of fatal crashes involving drivers with recorded prior DWI convictions and illegal alcohol levels also declined significantly in Maine, as did the proportion of fatal crashes involving fatally injured drivers with recorded prior DWI convictions and illegal alcohol levels. Most of the latter decline was due to a decline in alcohol-related fatalities of previously convicted drivers with very high BALs, of 0.15% or higher, at the time of the fatal crash. Each of these declines in Maine was significant relative to the rest of New England. CONCLUSION: Other states should consider instituting 0.05% BAL limits for convicted DWI offenders.

Accidents, Traffic↗