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Biomedical subjects

R Matthes

Publications and source records attributed to R Matthes.

18 recordsLinked to original sources
PubMed2001

Measurement of the individual exposure to 50 and 16 2/3 Hz magnetic fields within the Bavarian population.

This study investigates the individual magnetic field exposures at 16 2/3 and 50 Hz of 1952 people, selected from the Bavarian population. Personal flux density meters ("Field Watcher FW2A") were worn by the participants for 24 h. Every second, the flux density was recorded for both frequencies and for the three spatial axes (dynamic range per axis: several nT up to 100 microT at 50 Hz, 150 microT at 16 2/3 Hz). For 50 Hz fields, the mean of the 1,952 individual means was 0.101 microT and that of the individual medians was 0.047 microT. High level exposures occurred mainly during working hours. Only 2.4% of the subjects showed individual medians higher than 0.2 microT. About 53% of all volunteers were working on the day of recording. Levels for craftsmen (n = 148; mean individual mean: 0.166 microT) were generally higher than those for office workers (n = 624; mean individual mean: 0.107 microT). Flux densities exceeding 100 microT at 50 Hz were measured in 31 persons. The total time with such extreme exposures amounts to nearly 21 min, less than 0.001% of the total time for all measurements (5.3 years). To our knowledge, this is the first exposure study where 16 2/3 Hz magnetic fields (caused by electrified railways) have additionally been monitored over 24 h. For persons living next to railway lines, the mean individual mean (0.156 microT) and mean individual median (0.102 microT) were calculated. Over all, the mean exposures are only 0.1% of the magnetic flux density limit for 50 Hz (100 microT) and about 0.05% of the limit (300 microT) for 16 2/3 Hz recommended by the International Commission on Non-Ionizing Radiation Protection.

Adolescent↗
PubMed2001

[understanding and radiation hygiene assessment of solar UV exposure in Germany].

In order to monitor the natural ultraviolet (UV) radiation and to assess it from the point of view of radiation hygiene, the Federal Office for Radiation Protection (BfS) and the Federal Environmental Agency (UBA) have built up a common network for UV monitoring. Since 1993, the ground-level solar UV radiation has been measured at four sites in Germany every 6 minutes, with spectroradiometers in the wavelength range between 290 and 400 nm. Because erythema (sunborn) is of special interest in terms of radiation hygiene, the erythemal weighted irradiance was used as a measure for the biological effect of UV exposure. For this purpose, the measured spectral irradiance was multiplied by the relative erythemal weighting function, and the resulting function integrated from 290 to 400 nm. In the summer months of June and July 1999, the erythemal irradiance exceeded regularly the value of 175 mW/m2 in the south of Germany. In the north, values of not less than 160 mW/m2 were measured during this period. These values correspond to an UV index of more than 7 or 6, respectively--a high exposure regarding to the classification of the German Radiation Protection Commission (SSK), for which (absolute) sun protection is recommend. Between 1995 and 1999, the four sites were characterized by a small increase of the ground-level UV exposure of approx. 10%. Nevertheless, in consideration of the manifold factors affecting the acquired data, the measuring period of 5 years is still insufficient to demonstrate an ozone-dependent effect.

Erythema↗
PubMed1993

[Combined cryocoagulation of ciliary body and retina in neovascular glaucoma. Initial experience].

UNLABELLED: Therapeutic success in neovascular glaucoma with conservative and surgical methods is sadly inadequate. Based on the encouraging results we have obtained with transconjunctival cyclocryothermy in primary glaucoma and with peripheral cryopexy (transconjunctival cryotherapy), we applied these two methods in combination to treat neovascular glaucoma. PATIENTS: A total of 25 eyes in 23 patients were treated with the above method. The average preoperative bulbar pressure was 43 mmHg. RESULTS: The highest average reduction of pressure was obtained in weeks 2-4 after treatment (20 mmHg); 40% of the eyes were still compensated after 4 months (below 22 mmHg), 35% showed bulbar pressures between 26-28 mmHg, and 25% showed bulbar pressures about 35 mmHg. These patients had no troublesome symptoms. In all cases, a good improvement of rubeosis iridis was observed. The combined cryotherapeutic method of treating neovascular glaucoma is efficient in controlling the internal bulbar pressure.

Adult↗
PubMed1991

[Cryotherapy in the treatment of vitreous hemorrhage of various origin].

In 54 eyes from the same number of patients transconjunctival cryotherapy was performed (12 points and 8-10 circular ones in the outer retinal periphery) to influence the absorption of vitreous haemorrhages of different aetiology. The most frequent cause was the proliferative stage of diabetic retinopathy (53.7%) and vascular changes in atherosclerosis (39%). Haemorrhage of the vitreous persisted on average for five months. Eight months after the intervention complete or partial reabsorption led to improvement of the eyesight in 74% of the patients, no change was recorded in 16.6% and further deterioration occurred in 9.4%. No serious per- or postoperative complications were recorded, the method is unpretentious, can be used in ambulatory patients, it is repeatable and suitable also as preparation before vitreous surgery.

Adult↗
PubMed1991

[Equipment for spray-freezing in ophthalmology].

The authors discuss the theoretical background of the method of spray/freezing for destructive processes and their advantages. They demonstrate a cryo-apparatus IKG 3 for liquid nitrogen which is part of the Dresden equipment and was elaborated by the department for cryomedicine of the "Carl Gustav Carus" Academy in cooperation with the Technical University in Dresden. The apparatus produces a fine dispensable spray of the cooling mixture and permits treatment even of small tissue areas.

Cryosurgery↗
PubMed1991

[Clinical use of the spray-freezing method in ophthalmology].

The authors describe a therapeutic method using spray freezing in the treatment of malignant tumours of the eyelids and conjunctivae, trichiasis and distichiasis and forms of conjunctivitis vernalis which cannot be checked by drugs. The authors discuss the results assembled in a large group of patients during 1971-1987 (4,084 patients). The results provide convincing evidence that the method is successful in these indications and that it has preference before contact freezing. Treatment of all patients was implemented using the Dresden cryotherapeutic apparatus IKG 3.

Conjunctival Neoplasms↗
PubMed1990

[Technic and long-term results of cryogenic epilation in trichiasis and distichiasis].

The present paper communicates the technique and results of cryoepilation in 1,690 cases (94% trichiasis and 6% distichiasis). Only nitrogen cryotherapy devices are totally suitable for this, and the spray freezing method is to be preferred. The IKG unit developed by the authors, which has proved successful in particular for tumor therapy, is also ideal for cryoepilation. It generates a very tightly bundled nitrogen spray jet, thus permitting isolated freezing of the lid margin. In about 95% of the cases permanent epilation is achieved without undue trauma. In 5% the condition described by Fraunfelder as "secondary trichiasis" develops. Ocular pemphigoid is not a contraindication to cryotherapy.

Cryosurgery↗
PubMed1990

Functional and morphological changes in the eccrine sweat gland with heat acclimation.

Three adult male patas monkeys (11-15 kg) were heat acclimated by continuous exposure to an ambient temperature of 33 +/- 1 degree C at 13% relative humidity for 9 mo. During the last month, they were also exposed to 45 degrees C at 10% relative humidity for 4 h/day and 5 days/wk. Before and after 3 wk of acclimation, the animals were given a heat-tolerance test in which rectal (Tre) and mean skin (Tsk) temperatures, heart rate, and sweat rate (msw) were monitored during a 90-min exposure to 45 degrees C heat with 24% relative humidity under lenperone (1.0-1.4 mg/kg im) tranquilization. Maximal in vivo msw was also determined in response to subcutaneous injections (1 and 10% solutions) of methacholine (MCh). Before and after 9 wk and 9 mo of acclimation, sweat glands were dissected from biopsy specimens of the lateral calf, cannulated, and stimulated in vitro with MCh. Morphological measurements of isolated tubules were compared with maximal secretory rates produced by MCh stimulation. Three weeks of acclimation 1) reduced Tre and Tsk and increased msw during the heat tolerance test and 2) significantly increased maximal msw in response to MCh stimulation. Acclimation also increased (P less than 0.05) sweat gland size, as measured by tubular length and tubular volume. Maximal in vitro msw produced by MCh stimulation and msw per unit length of secretory coil also increased significantly. We conclude that heat acclimation increases the size of eccrine sweat glands and that these larger glands produce more sweat. They are also more efficient because they produce more sweat per unit length of secretory coil.

Acclimatization↗
PubMed1989

[A new device technic for cryotherapy of glaucoma].

With nitrogen cryotherapy, the authors achieve lasting normalization of intraocular pressure in more than 90% of their primary glaucoma cases. To accomplish this, the therapeutic parameters (working temperature, diameter of the applicator tip, duration of application, number of application points, applicator contact pressure) must be strictly defined and coordinated. The applicator contact pressure has hitherto been neglected in published data, although it dictates the heat transfer resistance between the applicator and the surface of the bulb and is therefore a major factor influencing the therapeutic effect. A device was therefore developed which indicates the applicator contact pressure continuously during therapy, both optically and acoustically. It renders cryotherapy just as effective as microsurgical methods, with no side-effects.

Ciliary Body↗
PubMed1988

[H-reflex latency, index and conduction velocity in healthy probands].

The HL, HI and HV were measured of 76 healthy persons at the age of 20 to 70 years. The length-dependent variation of the HL can be eliminated most favourable by calculating the HI. Because of the proved linear correlation between age and HI the use of age-specific HI-normal ranges is recommendable.

Adult↗
PubMed1988

[Significance of the H-index in the early diagnosis of uremic polyneuropathy].

In 68 patients suffering from chronic renal insufficiency in the stage of compensated retention (36 male, 32 female, 46.9 +/- 12.1 years, Serum creatinine level 250-1350 mumol/l) and in 28 patients treated by chronic hemodialysis (13 male, 15 female, 39.5 +/- 14.1 years) the H-index from the H-reflex arc latency was calculated in comparison with the motoric nerve line velocity. The H-index was a sensitive electroneurographical parameter and better suited for the early diagnosis of an uremic polyneuropathy than the estimation of the motoric nerve line velocity. In 51 patients suffering from chronic renal insufficiency and in 64% of the dialysis patients a pathological H-index was found.

Electromyography↗
PubMed1987

[Diagnostic value of the H-reflex index in alcoholic polyneuropathy].

We examined the H-reflex-index of triceps surae muscle (HI) and the motor nerve conduction velocity of the tibial nerve (mNLG) of 56 alcohol dependent patients. The results were compared with neurologic disorders, duration of the dependency and the type of alcoholism according to Jellinek. The HI showed significant more pathological changes than the mNLG.

Adult↗
PubMedDate not supplied

Folic acid treatment in males and females with fragile-(X)-syndrome.

Ten males with the fragile X (fra(X] syndrome were treated with folic acid (10 mg/day) for 4 months in a double-blind design study. To eight heterozygotes with mental impairment and fra(X), folic acid was given for 4 months (10 mg/day) in an effort to study possible beneficial effects of folic acid. Psychological and cytogenetic testing were carried out during the trial. There was no improvement in concentration, fine motor co-ordination, or comprehension in the adult male and female patients of the study. One patient showed improvement under a control medications. In the females, improvement was seen only in the youngest patient, a 5-year-old girl. Folate treatment does not seem to be effective in fra(X) adults, but may have some effect in children of both sexes with the disorder. Cytogenetic studies using peripheral lymphocytes showed that the fra(X) frequency decreased significantly (t = 0.00856; 1% level) only in cells cultured in a folic acid-free medium but not in cells cultured in a medium with added antifolate (methotrexate). This shows a "contamination effect" of folate-free culture medium after oral folic acid treatment of these patients. The decrease of fra(X) involves primarily the early-replicating X when culturing with folic acid-free medium. A synergistic suppression effect of "external folate" and BrdU is the most likely explanation of this phenomenon.

Adolescent↗