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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
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

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↗
PubMed1989

[Objectivization of the methods for recording the total contact surface and the number of occlusal contacts in static occlusion].

The occlusal contacts of teeth in a dentition have been analysed metrically with the aid of a new method. The outstanding advantage of this method is offered by the fact that the contacts of teeth are registered immediately in the subject and then evaluated with the aid of the teleplanimetric measuring variant. From error computation it follows that the method leads to reproducible and largely objective results. In 84 subjects with an average age of 16.9 +/- 3.7 years the total contacting area and the number of contacts in static occlusion were determined and examined with respect to specific groups.

Adolescent↗
PubMed1989

[Arthroscopic semitendinosus-plasty with lateral extra-articular stabilization in anterior knee joint instability].

Within the framework of a prospective study, 40 patients were examined postoperatively 12 months after their anterior cruciate ligament had been replaced by a doubled semitendinosus tendon arthroscopically combined with a lateral extra-articular procedure. "Second look" arthroscopy was possible in four cases. Evaluation was conducted according to the system of Müller and the Lysholm scoring system. According to the Müller system very good or good results were achieved in 97.5%; 95% of the patients achieved 91-100 points in the Lysholm scoring system. No substantial restrictions in the knee joint's range of movement were reported; there were also no other complications. The operative technique and the rehabilitation regimen are documented.

Adolescent↗
PubMed1989

A simple plant and tissue culture growth chamber for the regeneration of tobacco mesophyll protoplasts.

The isolation and regeneration of tobacco mesophyll protoplasts from fully developed leaves, an important methodological step in plant genetic engineering as well as in plant cell biology and physiology, has been proven unreliable to the extent that it has become a significant setback to basic research. This unfortunate situation is primarily due to the suboptimal physiological state of greenhouse-grown protoplast donor plants. A technically simple and inexpensive method, based on the utilization of commercial Phototron units, is described for the production of suitable tobacco donor plants. Furthermore, a modified version of such a culture unit can be used to regenerate plants from protoplast-derived calli.

Atmosphere Exposure Chambers↗