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Biomedical subjects

F Schmidt

Publications and source records attributed to F Schmidt.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Mercury and creatinine in urine of employees exposed to magnetic fields. A study of a group electrolysis-operators in Norzink A/S in Odda].

The results described are based on a study of 26 male cell house employees. They were exposed to a combination of static magnetic fields (3-10 mT) and low frequency oscillating magnetic fields of variable frequency and strength for eight hours a day over a period of four weeks. Every fifth week was spent off work. Urine samples collected at the end of the four weeks of exposure were compared with samples collected at the end of the week off work. The results show that the cell house workers excreted significantly more mercury in their urine after exposure to magnetic fields (p = 0.01). The mercury/creatinine ratio was also significantly higher after exposure (p < 0.01). These results support findings by Schmidt in a study from 1992 when the levels of mercury and creatinine in the urine of cell house workers were compared with the levels in office personnel.

Adult↗
PubMed1997

[Nuclear magnetic resonance tomography examinations of the urogenital diaphragm in comparison with corresponding histomorphologic findings (the controversy concerning the musculus transversus perinei profundus)].

The transversus perinei profundus muscle is a well known structure in found anatomical textbook. Fibers of this muscle are believed to form the so-called external urethral sphincter (musculus sphincter urethrae). Recently histomorphologic investigations have shown that there is no muscular connection between the musculus sphincter urethrae (external sphincter) and the muscle system of the pelvic floor. Furthermore, the external sphincter was found to be divided into parts: the transversely striated part (musculus sphincter urethrae transversostriatus) and the smooth part (musculus sphincter urethrae glaber). Similar to histomorphologic investigations, contrast-enhanced MR imaging has shown the musculus sphincter urethrae to be surrounded by fatty and connective tissue only. Neither in MRI nor in anatomical slices can any connection between the urethral sphincter and the muscle system of the pelvic floor to be found. Thus, on the basis of the results presented in this work it is concluded that the musculus transversus perinei profundus does not exist in the form described in textbooks.

Adolescent↗
PubMed1997

Long-term home studies of water balance in patients with nocturnal enuresis.

A 2-week, home-based study was conducted on 75 children with nocturnal enuresis to monitor the frequency of enuretic episodes and the volume of nocturnal urine production. The objectives of the study were to correlate nocturnal urine production to the occurrence of nocturnal enuresis and response to desmopressin (Minirin, DDAVP) treatment. Furthermore, patient compliance was evaluated. Enuresis episodes and nocturnal urine production was recorded every night during two base-line weeks without treatment and during 2 weeks with 20-40 micrograms desmopressin at bedtime. During both periods fluid intake and micturition volumes were recorded for 2 days. Desmopressin response was defined as > 50% reduction in wet nights during treatment. It was found that patient compliance was acceptable in most patients. Regarding urine output it was found that base-line nocturnal urine production was significantly higher during nights when enuresis occurred than during "dry" nights and significantly higher in desmopressin responders compared with desmopressin non-responders. During treatment with desmopressin, nocturnal urine production in desmopressin responders decreased to levels similar to those of non-responders. The results confirm inpatient circadian studies of urine output and emphasise the importance of nocturnal polyuria in patients with monosymptomatic enuresis. The response to desmopressin was found to correlate with the occurrence of nocturnal polyuria. Home studies were considered to be a useful tool in the characterisation of patients with nocturnal enuresis.

Administration, Intranasal↗
PubMed1997

The effect of the full bladder on vasopressin secretion in healthy young adults.

Interactions between the central nervous system, bladder and kidneys have been investigated for many years in animal studies and have shown that bladder distension, in animals, leads to decreased urine production. The objectives of the current study were to determine the effect of a full bladder on urinary output, vasopressin secretion and urine osmolality in humans. The study involved healthy volunteers. They were studied for a period of 48 hours. This period included two 24-hour studies, one involving regular and frequent voidings (to produce a minimal bladder filling) and the other voiding postponement (to produce maximal bladder distension). In contrast to enuresis studies a circadian rhythm of vasopressin secretion was observed in the males involved in this study, whereas no significant rhythm of vasopressin secretion could be detected in the female subjects. However, this study was unable to confirm that, in humans, a full bladder causes a decrease in urine production, an increase in vasopressin secretion or an increase in urine osmolality.

Adult↗
PubMed1997

[Mammography].

Today mammography represents the only imaging modality that decreases with the help of screening programs the mortality rate of breast cancer patients. This becomes increasingly necessary because already every tenth woman in Austria will get this tumor during her lifetime. There is conclusive evidence that the patients chance for survival depends on the clinical status of breast cancer at the time of diagnosis. Therefore every woman should undergo a yearly mammogram starting at 40 years of age. If sensitivity and specificity of mammography is under consideration one must differentiate its role during a screening program versus the situation of a symptomatic patient.

Adult↗
PubMed1997

[Value and importance of magnetic resonance tomography].

After 14 years of clinical practice, magnetic resonance imaging (MRI) has gained an important place among the imaging methods. For a physician not permanently occupied with these problems, the differential indications of MRI compared to ultrasound and computertomography (CT) are difficult to understand. Knowledge of capabilities and limitations, benefits and drawbacks, contraindications, future trends, and, in an era of shortage of financial resources, knowledge of some essential economic aspects will be helpful. This publication tries to present these aspects in a compact form were singular problems of MRI diagnostics can only partly be dealt with.

Cost-Benefit Analysis↗
PubMed1997

[Radiologic imaging of MALT lymphoma. (Comparison between stomach roentgen image, computerized tomography and magnetic resonance tomography].

The new classification of primary lymphomas of the stomach according to the MALT concept is very promising in therapy planning and prognostic estimation. This new classification sets strict requirements for imaging diagnostics. Besides endosonography which allows the determination of the infiltration depth in stages E I1 and E I2 in an excellent manner, computed tomography and, possibly, magnetic resonance tomography are indispensible for evaluation of higher stages and of the resectability of a lymphoma. Further MRI examinations are recommended.

Female↗
PubMed1996

Comparison of mammographic image quality in various methods of reconstructive breast surgery.

The purpose of our study was to evaluate mammographic image quality of various methods of reconstructive breast surgery with specific reference to the possibility of diagnosis of recurrent tumors. A total of 39 patients who underwent breast reconstruction following modified radical mastectomy were subject to clinical and mammographic examination. Three groups were formed: (a) autonomous tissue reconstruction (TRAM-flap; n = 9), (b) submuscular silicon gel prostheses (n = 21), and (c) supramuscular silicon gel prostheses (n = 9). Mammographic image quality of the groups was compared by two radiologists working together using a point system where five specific criteria were valued and scored. The result was tabulated into three quality levels: good, acceptable, and limited. Mammograms were assessed as good, acceptable, or limited, respectively, as follows: group I: 7 (77.8%), 1 (11.1%), 1 (11.1%); group II: 4 (19%), 11 (52.4%), 6 (28.6%); group III: 3 (33.3%), 4 (44.5%), 2 (22.2%). The TRAM-flap method of reconstruction displays a high degree of mammographic image quality and therefore is preferable with respect to early diagnosis of recurrent tumors.

Adult↗
PubMed1995

Malignant schwannoma of the breast.

Malignant schwannoma (MS) is a tumor of the Schwann or nerve sheath cells, most frequently occurring in the lower and upper extremities, trunk and head region. We report the third known case of MS of the breast, which occurred in a 27-year-old woman. The palpable tumor, about 1.2 cm in diameter, was localized in the upper inner quadrant of the right breast. After ultrasonography, mammography and fine needle aspiration cytology, the tumor was removed surgically.

Adult↗
PubMed1995

Heavy metal mediated inhibition of rBAT-induced amino acid transport.

rBAT, a protein which is located in the brush border membranes of intestine and renal proximal tubule cells, was recently shown to induce electrogenic countertransport of neutral and dibasic amino acids after its expression in Xenopus oocytes. Here, we studied the effects of heavy metals on rBAT induced amino acid transport in Xenopus oocytes to clarify a possible involvement of rBAT in heavy metal-induced aminoaciduria. The heavy metals Hg2+ and Pb2+ inhibited rBAT-induced amino acid transport with a different profile of action. The Pb2+ mediated inhibition occurred rapidly upon superfusion and was readily reversible upon washout. The maximal inhibition caused by Pb2+ was about 50% of the amino acid-induced currents at an apparent affinity (Km) of about 10 microM. In contrast, the Hg(2+)-mediated inhibition occurred rather slowly, depending on its concentration, and was not reversible during washout with control solution. However, the Hg(2+)-mediated amino acid transport inhibition could be reversed with Hg2+ chelating agents and reducing compounds. Other oxidative agents, such as the membrane permeable 2,2'-Dithio-bis(5-Nitropyridine) (DTNP), but not the membrane impermeable 5,5'-Dithio-bis (2-Nitrobenzoic acid) (DTNB), mimicked the effect of Hg2+, and their effect could similarly be reversed with 2,3-Dihydroxybutane-1,4-dithiol (DTE). In conclusion, Pb2+ and Hg2+ inhibit rBAT-induced amino acid transport in a noncompetitive, allosteric fashion. Blockade of rBAT-induced amino acid transport may be involved in aminoaciduria following mercury or lead intoxication.

Amino Acid Transport Systems, Basic↗
PubMed1995

Serotonin acts as a radical scavenger and is oxidized to a dimer during the respiratory burst of human mononuclear and polymorphonuclear phagocytes.

Isolated human mononuclear and polymorphonuclear phagocytes were stimulated in the presence and absence of serotonin (5-HT), the major secretory product of activated platelets, and the release of reactive oxygen metabolites during the respiratory burst was assessed by luminol-enhanced chemiluminescence. In the presence of 5-HT, a dose-dependent suppression of the chemiluminescence signal occurred, irrespective of the stimulus used to elicit the respiratory burst. A similar suppression of luminol-enhanced chemiluminescence was also seen in a radical generating cell free system. 5-HT was found to be oxidized by the reactive oxygen species released by stimulated phagocytes. This oxidation is prevented in the presence of other antioxidants. The major 5-HT oxidation product was isolated by gel chromatography and identified by mass-spectrometry as a 5-HT dimer, probably 5,5'-dihydroxy-4,4'-bitryptamine. It is concluded that the 5-HT released from activated thrombocytes at sites of inflammation and endothelial cell damage acts as a true scavenger of reactive oxygen species generated during the respiratory burst of stimulated phagocytes and may thus modulate various aspects of cell-mediated defence reactions.

Free Radical Scavengers↗
PubMed1995

The impact of data-analysis methods on cumulative research knowledge: statistical significance testing, confidence intervals, and meta-analysis.

The methods of data analysis used in research have a major effect on the development of cumulative knowledge. Traditional methods based on statistical significance testing have systematically retarded the growth of cumulative research by making it virtually impossible to discern the real meaning of research literatures. Meta-analysis makes it possible to demonstrate graphically the high price the research enterprise has paid for its reliance on significance testing. But in addition to these demonstrations, reform will require that researchers come to understand that the benefits they see as flowing from the use of significance tests are illusory. In research practice and in training of researchers, we must use and teach appropriate data analysis methods: point estimates of effect sizes and confidence intervals within individual studies, and meta-analysis in the integration of multiple studies to produce final conclusions. These reforms are essential to the progress of cumulative research knowledge.

Analysis of Variance↗
PubMed1995

Lack of pineal growth during childhood.

During childhood, serum melatonin concentrations drop by approximately 80%, but the 24-h melatonin excretion is stable. Arrest of pineal growth after the end of infancy has been proposed as one possible mechanism underlying that phenomenon. To test this hypothesis, we reviewed 332 magnetic resonance imaging brain studies, classified as normal, of endocrine-normal children, aged 1 day to 15 yr, and estimated the pineal and pituitary sizes. The pineal was identified in 277 of 332 magnetic resonance imaging studies (83%). The average size (mean +/- SEM) of the pineal gland (transaxial diameter, 5.6 +/- 2.1; midsagittal diameter, 5.0 +/- 2.4; planimetric area, 28.5 +/- 17.8) did not differ with age. A total of 74 of 277 pineals with cysts (26.7%) were found. The occurrence of pineal cysts was equally distributed among the different age groups (chi 2 = 11.6; df = 14; P = 0.7). Ten pineals showed more than 1 cyst (3.6%). The pituitary was identified in 325 of 332 brain images (97.9%). The average pituitary size increased by some 100% from 1 to 15 yr of age [transaxial diameter: F = 2.2; P = 0.005 (by two-way analysis of variance); midsagittal diameter: F = 3.7; P = 0.0001; planimetric area: F = 7.1; P = 0.0001]. The pituitary was slightly larger in females than in males [midsagittal diameter: F = 8.8; P = 0.003 (by two-way analysis of variance); planimetric area: F = 7.9, P = 0.005]. The data presented indicate a lack of a discernible pineal growth after age 1 yr, which contrasts with pituitary development in the same individuals. The data are in agreement with a hypothesis suggesting a growth arrest of the pineal after infancy.

Adolescent↗