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Biomedical subjects

F Hoffmann

Publications and source records attributed to F Hoffmann.

At least 73 records · Page 4Linked to original sources
PubMed1994

HLA-B and -DR match reduces the allograft reaction after keratoplasty.

Since 1983, corneal grafts have been routinely obtained from multiorgan donors and allocated to the patient with the greatest HLA compatibility. At follow-ups in 248 primarily clear corneal grafts, grouping according to the HLA mismatch rate revealed that the incidence of allograft reactions did not differ significantly for HLA-A but certainly did for HLA-B (P < 0.01) and, in patients with a poor prognosis, for HLA-DR as well (P < 0.05). Grouping the patients according to the mismatch rate of the total of four HLA-B and -DR antigens disclosed the incidence of allograft reactions to be markedly increased by a mismatch of more than two antigens (P < 0.05). The relative risk of an allograft reaction is increased by factors of 5.1 in patients with a good prognosis and 5.5 in those with a poor prognosis. The adverse influence of a postoperative inflammation on the occurrence of an allograft reaction as seen in nonmatched donor material is no longer present in matched donor material if the prognosis is good and no longer significant if it is poor (P < 0.09). The inflammation-promoted expression of HLA antigens is of less importance for graft survival if the difference in the HLA antigens is reduced by the match.

Cornea↗
PubMed1993

[Spontaneous dislocation of a silicone disk lens 4 months postoperative into the vitreous body].

We report on a patient who experienced an acute deterioration in visual acuity at night four months after implantation of a silicon-disc lens into the capsular bag. On examination, the artificial lens was localized preretinally. The capsular equator was fibrous, but had retained its circular shape. The posterior capsule was ruptured. The rupture may be explained by tension in the posterior capsule, which is only 1-4 microns thick, within the shrunken capsular bag, and by an acute increase of intraocular pressure caused by rubbing of the eyes during sleep.

Aged↗
PubMed1993

Mechanical methods in refractive corneal surgery.

Keratorefractive surgery has developed rapidly over the past decade. For patients with aphakia, however, posterior chamber lenses are safer and more predictable than refractive corneal surgery; myopia is the greatest challenge to this type of surgery. No technique as yet has an accuracy that is adequate for the general treatment of myopia. Keratotomy is the most common procedure currently performed for the correction of mild myopia and astigmatism. Results are less accurate and less stable with myopic than with aphakic epikeratoplasty. Although it is technically more difficult, keratomileusis seems to be more predictable than epikeratophakia. Nonfreeze lamellar corneal surgery accelerates wound healing. Synthetic lenses and ring-shaped implants are also being developed to modify corneal refraction. Current research is directed toward laser stromal keratomileusis on discs that are removed from the cornea using a microkeratome.

Corneal Stroma↗
PubMed1993

Increased hydrolase activities in the human trabecular meshwork of glaucomatous eyes.

Alterations in the metabolic functions of trabecular meshwork (TM) cells are thought to be involved in the pathogenesis of primary open-angle glaucoma (POAG). In an investigation of this possibility, 30 trabeculectomy specimens from patients with POAG were examined histochemically for 11 lysosomal and membrane-bound enzymes. The patients ranged from 48 to 87 years in age. The degree of enzyme staining was compared with that of 15 age-matched controls obtained from an eye bank at less than 24 h after death. There was no history of eye disease in the controls. The enzymes examined were: dipeptidylpeptidases II and IV (DPPII and IV); beta-glucuronidase (beta-GLUC); acid-beta-galactosidase (s beta-GAL); N-acetyl-beta-D-glucosaminidase (NAG); nonspecific esterase (UE); acid phosphatase (SP); alkaline phosphatase (ALP); gamma-glutamyltransferase (GGT); and aminopeptidase A and M (APA and APM). Evaluation of the specimens was performed by two observers and by computer-aided optic densitometry. Results showed increased staining of SP, UE, GGT and APM in the pathological specimens as compared with the controls. SP and UE indicate phagocytic activity, APM is involved in collagen turnover and GGT participates in both drug detoxification and the breakdown of glutathione in the gamma-glutamyl cycle. Our observations show different hydrolase activities in the TM cells of human glaucomatous eyes as compared with normal values, suggesting that such metabolic differences may be related to the pathogenesis of POAG.

Aged↗
PubMed1993

Comparison of corneal lenticules produced for keratokyphosis and keratophakia.

Apart from the original freezing technique, there are three non-freeze keratomileusis procedures, in which the cornea is first deformed before a tissue lens is severed from the side. Two measuring procedures were used to measure corneal lamellae separated from pig eyes by means of the microkeratome. The following parameters were determined: the size of the severed lamellae, given as the two diameters in the feed direction of the microkeratome and perpendicular to it, and the profiles of the axial sections of these lamellae as determined by means of the universal measuring microscope (UMM). Both measuring procedures had a precision of +/- 3 microns. The results obtained with different blade types were compared, and an optimized blade was developed. The corneal lamellae separated parallel to the surface using the optimized blade were of higher quality than those cut with the Barraquer microkeratome. The variation coefficient was 0.9% for the Berlin microkeratome and 6.0% for the Barraquer microkeratome. The profile studies demonstrated that rotationally symmetrical tissue sections can be obtained with the Berlin microkeratome. The lens-shaped tissue sections separated from pig cornea showed an undercorrection. Further studies are needed to determine whether a higher refraction precision can be achieved in lamellae cut from human donor cornea.

Animals↗
PubMed1993

[Subablative gentamycin therapy in Menière's disease].

We have treated 20 patients suffering from unilateral Morbus Meniere (2 x 12 mg gentamicin for 7 days). These patients were controlled for 24 months. In 95% we regarded a complete or substantial control of definitive spells ("American Committee on Hearing and Equilibrium guidelines for reporting treatment results in Meniere's disease", Otolaryngol. Head and Neck Surg. 10/19-85). Only 1 patient with pretherapeutic equal caloric response showed a post-therapeutic destroyed vestibular apparatus on the treated ear. In the other 7 patients (35%), who had a loss of vestibular function after therapy, there was an already pretherapeutic more or less noticeable caloric hypoexcitability. It is possible to induce an only subablative damage with a clinical success in 95%.

Audiometry, Pure-Tone↗
PubMed1992

Acetylcholinesterase. Two types of modifications confer resistance to insecticide.

Quantitative and qualitative changes in acetylcholinesterase confer resistance to insecticides. We have constructed several Drosophila melanogaster strains producing various amounts of enzyme by P-mediated transformation. Toxicological analysis of these strains demonstrates that resistance to organophosphorus insecticides is correlated with the amount of acetylcholinesterase in the central nervous system. Resistance may also be qualitatively determined. Comparison of the Drosophila acetylcholinesterase gene between a resistant strain caught in the wild and a wild type susceptible strain only revealed one nucleotide transition resulting in the replacement of a phenylalanine by a tyrosine. Flies mutant for acetylcholinesterase and rescued with a minigene mutagenized for this same transition produced an altered enzyme which renders flies resistant to pesticides.

Acetylcholinesterase↗
PubMed1992

Minigene rescues acetylcholinesterase lethal mutations in Drosophila melanogaster.

The gene encoding acetylcholinesterase in Drosophila melanogaster is over 34,000 base-pairs long. We have constructed a 5800 base-pair minigene containing 1500 base-pairs of genomic sequence upstream from the transcription start spliced to the coding sequence, but lacking the nine introns. After germline genetic transformation, this minigene rescues acetylcholinesterase lethal mutants. Tissue-specific distribution appears normal. This allows us to test site-directed mutations of acetylcholinesterase. In a first effort, deletion of most of the unusual 1000 bases leader and its intriguing short open reading frames showed no effect on gene expression. The way is open to study in vivo the structure-function relationships of acetylcholinesterase and insecticide resistance.

Acetylcholinesterase↗
PubMed1992

Prediction of phenotype for acetylation and for debrisoquine hydroxylation by DNA-tests in healthy human volunteers.

The debrisoquine/sparteine-type polymorphism of drug oxidation and the polymorphism for acetylation are two common inherited variations in human drug metabolism. The phenotypes for hydroxylation and acetylation can be predicted be newly developed methods based on mutation-specific amplification of DNA by the polymerase chain reaction (PCR), which also allow for identification of heterozygous carriers of one mutant allele. In the present study, the results of genotyping of 81 healthy European volunteers were compared with the phenotype obtained by the classical biochemical approach using debrisoquine and caffeine as probe drugs. Genotyping correctly predicted all 73 extensive metabolisers (EMs) and 6 out of 8 poor metabolisers (PMs) of debrisoquine. All 48 rapid acetylators and 33 of 35 slow acetylators were predicted. Overall, the DNA analysis result matched the in vivo phenotype in 97.5% of individuals.

Acetylation↗
PubMed1992

[Capsulorhexis using an ultrasound-controlled cannula].

Every cataract surgeon performing phacoemulsification has unintentionally damaged the posterior capsule. Thus he knows that the device is suitable for cutting the lens capsule. In recent years, I have performed various modifications of capsulorhexis with the aid of an ultrasound-guided cannula in all patients undergoing phacoemulsification. The following method proved to be practicable: The ultrasound-guided cannula is pressed on the lens capsule at 12 o'clock, thus opening the anterior capsule; the cannula is consecutively guided in two semicircular movements from 12 o'clock to 6 o'clock, and the anterior capsula is torn and cut open by directing the opening of the cannula toward the center of the pupil and simultaneously on the anterior capsula and away from the iris, thus making it possible to cut directly at the pupillary margin without damaging the iris. The anterior capsular tear has a smooth circular edge at the intersection of the two semicircles of the capsulorhexis, while a triangular flap directed towards the center of the pupil is often formed at 12 o'clock. At the end of phacoemulsification, the flap is aspirated with the suction rinsing device and cut off with a sharp cannula. This procedure simplifies and accelerates phacoemulsification.

Cataract Extraction↗
PubMed1991

[The development of methods for the objective assessment of occlusal parameters].

For reasons of different data in literature on occlusal parameters and their metric registration, at the beginning of the 80's two methods independent of each other were developed--the capacity measuring method and the quasiplanimetry method to register the total occlusal contact area and the number of occlusal surfaces of contact at dental casts. The results obtained independently from each other showed a high degree of correspondence. That's why the method of quasiplanimetry was further developed and used for the direct analysis of enorally obtained wafers of different characteristic. The method is improved now with a modern system of digital analysis. The results obtained up to now admit the conclusion that the occlusion of the teeth represents an individual condition of high variability. With the reproducible method used individual occlusal parameters can be numerically registered.

Dental Occlusion↗
PubMed1991

The total surface and number of occlusal contacts in the static and dynamic occlusion of the teeth. Development of the methods.

For reasons of different data in literature on occlusal parameters and their metric registration at the beginning of the eighties two methods, independent from each other, were developed to registrate the total occlusal contact area and the number of occlusal surfaces of contact on dental casts--the capacity measuring method and the quasi-planimetry method. The results obtained independently from each other show a high degree of correspondence. Because of its easy handling the method of quasi-planimetry was further developed and used for direct analysis of enorally obtained wafers of different characteristics. The total surface of occlusal contacts in the static occlusion ran up to 4-6 mm2, and the number of stops to 19-30. The method of qualitative and quantitative analysis of occlusal parameters is improved with a modern system of digital analysis. The results obtained up to now admit the conclusion that the occlusion of the teeth represents an individual condition of high variability.

Adolescent↗
PubMed1991

[Psychosocial problems in patients with chronic osteomyelitis].

52 patients suffering from a chronical bone infection were followed up with a special interest in psychosocial problems. In all cases psychosocial disturbances of different importance were evaluated. Possible causes have to be seen in long time of hospitalisation (average = 304 days), and apparent inadequate enlightenment of patients and in functionally and cosmetically insufficiencies. Conclusions are shown for the management in treatment of chronical bone infections.

Activities of Daily Living↗
PubMed1990

Pollen germination is impeded by tap water.

Pollen germination in vitro is totally inhibited in tobacco (Nicotiana tabacum) and other species if tap water is used to prepare the germination medium. This effect is already fully present if tap water accounts for only 25% of the medium. Furthermore, the pollen grains deteriorate rapidly and the culture medium turns yellowish-brown. The water toxicity is not caused by one or several compounds regularly monitored by the water authorities but can be removed by ion exchange purification. Although the factor(s) responsible for the inhibition were not identified, the study clearly shows the presence of such a contaminant in three different Orange County (Southern California) water wells. The fact that a fundamental botanical process like pollen germination is inhibited by a factor in drinking water not included in water quality control causes some general health concern. In addition, crop yield might be largely reduced if overhead spray irrigation with this water is utilized. The experiments also suggest that pollen germination in vitro could serve as a sensitive and simple bioassay for water quality.

Journal Article↗
PubMed1990

Accuracy of the microkeratome keratectomies in pig eyes.

Keratokyphosis is a procedure of lamellar refractive corneal surgery in which corneal tissue does not have to be frozen. Corneal lamellae of 30 pig eyes were separated with either the Berlin microkeratome developed for keratokyphosis or the Barraquer microkeratome. The layer thickness was measured within the optical area at 25 measuring points 0.2-mm apart using the Universal Measuring Microscope. Corneal lamellae separated parallel to the surface by means of the Berlin microkeratome showed layer-thickness differences of 0.008 +/- 0.028 mm in the optical zone between the beginning and end of the incision. When using a convex applanation surface in the microkeratome with an optical zone of 5 mm and a vertex of 0.22, 0.2, and 0.15 mm, the vertex of the central part of the optical zone in the corneal disc attained a value of 0.114 +/- 0.018 mm instead of 0.114 mm (100%), 0.075 +/- 0.015 mm instead of 0.105 mm (72%), and 0.076 +/- 0.014 mm instead of 0.080 mm (84%) (mean +/- standard deviation [SD]). When using a concave applanation surface with the same vertex, it attained 0.076 +/- 0.020 mm (67%), 0.075 +/- 0.019 mm (72%), and 0.067 +/- 0.027 mm (84%). The measured vertex of the corneal lamellae was shifted up to 0.8 +/- 0.5 mm in the feed direction of the microkeratome, probably due to the frictional forces acting on the blade during the cutting process. After separation of the lamellae, the cut surface of the eye was measured planimetrically.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Combined valuation of the success of therapy of orthodontic anomalies, periodontal diseases and dental caries].

Using the DMF/T, GPM/T and CPITN-index systems, the numerical evaluation method according to Eismann and measuring the occlusal contact areas in static occlusion in 101 orthodontically treated adolescents and young adults the effect of complex preventive and therapeutic programs was studied. The used parameters allow to characterize oral health status. After completing the orthodontical treatment there is a need to continue preventive programmes and therapeutic interventions in adults to reach stable oral health conditions.

Adolescent↗
PubMed1990

[Psychosocial factors of preserving health? Prospective studies of breast cancer, bronchial cancer and fibrocystic mastopathy].

Do psychosocial factors affect the development of health? 156 patients were interviewed and tested before a breast biopsy or before the initial medical treatment of lung cancer. Multiple regressions examined the influence of age, diagnosis (tumor stage) and different psychosocial parameters as dependent variables the development of health after 2 or 5 years as independent variables. The breastbiopsy-group (n = 52) shows five psychological variables being effective in a positive (health promoting) manner: autonomy, emotional outlet, expression of one's needs, family support, lack of life stress. In lung cancer (n = 104) the development of health 2 years after diagnosis is only influenced by the type of tumor (small cell versus non small cell) and by the initial tumor stage. A structuralequation model (LISREL) shows for the first 3 months of illness that almost exclusively biological variables have an influence on psychological variables. Despite this family dynamics had a moderate effect on the patient's general wellbeing (Karnoffsky-Index).

Adult↗