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Biomedical subjects

D Schmidt

Publications and source records attributed to D Schmidt.

At least 271 records · Page 15Linked to original sources
PubMed1995

Interference effects of mental imagery on a motor task.

It can be argued that imaginary practice and physical practice are functionally similar. Evidence in support of this hypothesis comes from several experiments demonstrating that interference effects from imaginary practice in motor learning and motor memory are similar in both direction and size to those resulting from physical practice. The purpose of the present study was to provide additional support for this finding using a retroactive interference paradigm. Sixty participants were required to practise performing a simple motor task that was to be completed in a criterion time of 700 ms. They then were randomly assigned to one of six groups. These groups differed in the amount and type of interpolated practice they experienced. One physical practice group attended one session of interpolated activity involving physical practice of another motor task. The other physical practice group participated in two such sessions. One imagery group attended a single session entailing imaginary practice of the same interpolated motor task, while the other imagery group had two such sessions. A fifth group experienced a combination of physical practice and rest periods for two interpolated sessions. A control group did not experience any interpolated activity sessions. Following the interpolated activity sessions, all groups were given a retention/reacquisition test on the original motor task. Imaginary and physical practice during the interpolated activity sessions caused similar interference effects on retention/reacquisition. All groups showed greater deviation from the criterion movement time (700 ms) during the retention test than the control group, and these deviations were in the expected direction given the nature of the interpolated motor task.

Adolescent↗
PubMed1995

Topography of the cortical motor hand area: prospective study with functional MR imaging and direct motor mapping at surgery.

PURPOSE: To localize the cortical motor hand area with functional magnetic resonance (MR) imaging and electrical stimulation at surgery and to detect changes due to central lesions. MATERIALS AND METHODS: Fast-gradient-echo and functional MR images of the brain were acquired in four healthy volunteers and six patients with tumors in the central region before, during, and after repetitive opening and closing of the hand. Open brain surgery was performed, and the exposed cortex was stimulated. RESULTS: At functional MR imaging, circumscribed changes in signal intensity that correlated in time with the task were seen in the central region of the contralateral brain. In the healthy volunteers, the area of change was spotlike and projected into the posterior bank of the precentral gyrus. In four of the six patients, this area was diffuse and projected into the precentral gyrus. The locations of the cortical hand area as determined with intrasurgical mapping and functional MR imaging were identical. CONCLUSION: Identification of the cortical area responsible for motor hand function was similar with functional MR imaging and with direct stimulation at surgery. A space-occupying lesion can change the cortical representation of motor hand function.

Adult↗
PubMed1995

[Transvaginal ultrasound of "placental-site trophoblastic tumor"].

The case of a placental-site trophoblastic tumor (PSTT) is described. Transvaginal sonography revealed a vascularized tumor mass with a deep invasion of the myometrium, partly with echogenic, solid parts and partly multiple echo-free cystic lesions. The maximum size of an echo-free cystic lesion was 4.4 cm. Doppler exploration indicated the presence of blood flow in all these cystic lesions. Distinctly abnormal low flow indices were prominent in the whole tumor area. According to the clinical results and the slightly positive levels of human chorionic beta-gonadotropin (100-1,000 IU/l postpartum), this tumor was classified as malignant trophoblastic disease, most likely PSTT. The authors conclude that, in the case of a patient with suspected trophoblastic disease and in view of the sonographic findings, PSTT may be a valid differential diagnosis, particularly if larger cystic lesions of more than 3 cm in diameter are found in the tumor bed together with evident blood flow at a low vascular resistance.

Adult↗
PubMed1995

Extramedullary hematopoiesis and intratumoral production of cytokines in childhood hepatoblastoma.

Extramedullary hematopoiesis is a characteristic feature of hepatoblastoma (HB). We investigated 15 HB to characterize intratumoral hematopoietic foci and to find clues to the pathophysiology of their formation. By conventional histology and immunohistochemistry, we found erythroblasts in all and megakaryocytes in 10 of the HB, whereas granulocyte and monocyte precursor cells could not be identified in hematopoietic foci of any tumor. Only a minority of erythropoietic cells in these foci contained fetal Hb (HbF). We recently found that HB cells produce IL-1 beta and thus stimulate stromal cells to secrete IL-6. We therefore searched for other hematopoietic cytokines in HB. Supernatants of primary HB cultures were subjected to ELISA, bioassayed, and immunoblotted. We detected erythropoietin (EPO) in 11 of 15, stem cell factor (SCF) in 7 of 11, granulocyte colony-stimulating factor (G-CSF) in 4 of 15, granulocyte/macrophage colony-stimulating factor (GM-CSF) in 6 of 15, IL-3 in 1 of 12, leukemia inhibitory factor (LIF) in 1 of 9, and macrophage colony-stimulating factor (M-CSF) in 1 of 8 conditioned media. With immunoenzymatic labeling we localized EPO and SCF to the cytoplasm of epithelial HB cells, whereas stromal cells and cells of immature fibrous tissue of mixed HB expressed SCF, G-CSF, GM-CSF, LIF, and M-CSF. EPO and SCF could also be detected in extracts of epithelial HB cells. We conclude that, in HB, erythropoiesis and megakaryopoiesis but not the granulocyte-macrophage lineage is induced by fetal and embryonal tumor cells in cooperation with stromal cells by locally secreted cytokines.

Carcinoma, Hepatocellular↗
PubMed1995

Diagnostic assessment of two novel proliferation-specific antigens in benign and malignant melanocytic lesions.

The aim of this study was to gain a thorough insight into the proliferative activity of benign and malignant melanocytic tumors. A total of 314 cases were examined by immunohistochemistry on paraffin-embedded material. The growth fraction was assessed by means of two monoclonal antibodies, Ki-S1 and Ki-S5, which react with two different proliferation-specific nuclear antigens. Additionally, HMB-45 was used as a marker of melanocytic activation. Statistically significant differences (P < 0.01) in the proliferation rates were found between common acquired nevi, Spitz's/Reed's nevi, primary cutaneous melanomas, and metastatic melanomas, whereas dysplastic nevi were hardly distinct from other nevi of the compound type. In melanoma, the growth fraction correlated well with the tumor stage but poorly with HMB-45 expression and mitotic count. Along with tumor progression, an increasing heterogeneity of proliferation indices was observed. Our results provide no evidence for a progression from dysplastic nevi into melanoma. They indicate that the assessment of the proliferative activity may be of considerable diagnostic help in cases of uncertain histology and that it might contribute to an alternative concept for the classification of melanocytic tumors.

Adolescent↗
PubMed1995

[The motor hand area. Noninvasive detection with functional MRI and surgical validation with cortical stimulation].

In this study, activation of cortical sites by specific motor tasks (opening and closing of the hand) was examined by fMRI utilizing the blood-oxygen-level-dependent (BOLD) technique. fMRI was employed in five volunteers and in six patients with tumors in the vicinity of the central region. In the patients, the fMRI data and intraoperative cortical mapping were compared. Our results indicate good correlation of these two methods and that there are no significant differences in the localization of the motor hand area.

Adult↗
PubMed1995

[Fatigue fractures of the sacrum in primary biliary liver cirrhosis].

Insufficiency fractures of the sacrum are found in women after radiation therapy of the pelvis and those suffering from postmenopausal and steroid-induced osteoporosis. We report two female patients with insufficiency fractures of the sacrum occurring on the basis of a primary biliary cirrhosis. Both patients had simultaneous Tarlow cysts of the sacrum. The fractures were diagnosed by computed tomography. The findings were sclerotic bone changes, running from the ventral and lateral parts of the lateral mass of the sacrum parallel to the adjacent sacro-iliac joints. These fractures exhibited increased uptake in bone scintigraphy and were responsible for local pain. In one of the patients, the bilateral fractures healed four months after transplantation of the liver was performed.

Female↗
PubMed1995

[Disorders of color perception and increase glare sensitivity in phenytoin and carbamazepine therapy. Ocular side effects of anticonvulsants].

Advanced psychophysical tests, performed in 42 epileptic patients, show that the antiepileptic drugs phenytoin and carbamazepine can specifically affect the retinal function, while Valproic Acid and the epileptic seizures do not. The Farnsworth-Munsell 100-Hue and Panel D-15 désaturé tests revealed an accumulation of errors along the tritan/tetartan axis (blue colour vision deficiencies) and a high total error score. The same defect was shown by measurement of the spectral sensitivity functions. The results obtained for mesopic vision and especially glare sensitivity measured by nyktometry were markedly affected in these patients compared to a normal population. The enhanced sensitivity to glare is mainly the only one symptom complained by the patient. We propose a screening method for early detection of phenytoin- and carbamazepine-induced neurotoxicity. The literature of ocular side effects of anticonvulsant drugs is carefully reviewed.

Adolescent↗
PubMed1995

[Sensitive physiologic perceptual tests for ocular side effects of drugs exemplified by various anticonvulsants].

Advanced psychophysical tests, performed in 42 patients who have seizures, showed that the widely used antiepileptic drugs, diphenylhydantoin and carbamazepine, can specifically affect retinal function, while valproic acid and the epileptic seizures do not. The Farnsworth-Munsell 100-Hue and Panel D-15 désaturé tests revealed an accumulation of errors along the tritan/tetartan axis and a high total error score. As shown by measurement of the so-called transient tritanopia and by determination of the spectral sensitivity, this blue vision defect is not only due to loss of postreceptoral interaction between long- and short-wavelength-sensitive cones, but is also based on a disturbance in the receptor mechanism itself. The dark adaptation curve was not affected. As determined by cone flicker thresholds during dark adaptation, the inhibitory action of rods on cones is reduced. The results obtained for mesopic vision and especially glare sensitivity measured by nyktometry were markedly affected in these patients compared to the normal population. The psychophysical methods provide a very sensitive test for early detection of drug-induced retinal dysfunction and allow clear differentiation between the loss of a receptor mechanism and a defect in the neuronal interaction between photoreceptors in the human visual system induced by antiepileptics.

Adolescent↗
PubMed1995

Dosimetry of iodine-123-epidepride: a dopamine D2 receptor ligand.

UNLABELLED: Substituted benzamides have been shown to have very high affinity and specificity for the dopamine D2 receptor. One of these is radiolabeled epidepride, an iodine-substituted benzamide currently under evaluation as a SPECT imaging agent. Detailed estimates of the radiation absorbed dose to 26 organs and the whole body from [123I]epidepride have been calculated. METHODS: The dosimetry calculations use a combination of in vivo uptake and biodistribution data from one rhesus monkey and seven humans to estimate residence times in eight organs. The computer program MIRDOSE2 was used to calculate the dosimetry. RESULTS: Results indicate that 75% of the radioactivity is cleared through the urinary tract while the remaining radioactivity clears through the gallbladder and intestinal tract. The radiation absorbed dose can be minimized by administering a high lipid content meal 1.5 hr postinjection to empty the gallbladder and by giving large volumes of fluids throughout the study to induce increased urinary output. CONCLUSION: By emptying the gallbladder and urinary bladder, the lower large intestine becomes the critical organ, 0.102 mGy/MBq (0.38 rad/mCi) followed by the upper large intestine, 0.092 mGy/MBq (0.34 rad/mCi). The effective dose equivalent is 0.025 mSv/MBq (0.092 rem/mCi).

Animals↗
PubMed1995

[Lymphohistiocytic infiltration of endometrial adenocarcinoma].

Mononuclear cells adjacent to endometrial adenocarcinoma were evaluated in 8 biopsies by the immunoperoxidase technique. Between benign and malignant tissue a remarkable infiltration of CD45+, CD3+, CD4+, CD8+, and CD14+ cells could be observed. B cells (CD19) and NK cells (CD57) were rare. Tumor-infiltrating lymphocytes were only sparsely distributed. The findings suggest a cellular, yet ineffective, immune reaction of the host against the tumor at the borderline between benign and malignant tissue.

Adenocarcinoma↗
PubMed1995

[Diagnosis of the site and extent of breast carcinoma].

The value of X-ray-mammography, ultrasound, and MRI are compared with regard to their results in localization, differential diagnosis, and staging of carcinomas of the breast. For microcalcifications that are only imaged by mammography, X-ray is superior to the other imaging modalities and remains method of choice. Ultrasound is the most useful to differentiate cystic and solid lesions. The value of MRI is not yet proved sufficiently except in conservative and plastic surgery of breast carcinoma.

Biopsy↗
PubMed1995

Histopathology of childhood renal tumors.

The different subtypes of childhood renal tumors are well defined both clinically and pathologically. Classification and estimation of prognosis are feasible even after chemotherapy. A small group of tumors remains in which an estimate of prognosis is difficult. This is especially true for Wilms tumors with persistent blastema after chemotherapy. It is to be hoped that studies of the molecular genetics of these tumors will yield new data that will help refine therapeutic strategies.

Anaplasia↗
PubMed1995

[Bathing water related diseases: the Carinthian Sentinel Project as the source of epidemiological data].

The federal country of Carinthia is known for its lakes and ponds, which are extensively used for bathing. The water quality is monitored regularly in accordance to the EC-Directive 76/160/EC and especially to the more rigorous Austrian Standard M6230. Since redevelopment measures of the lakes have been nearly finished the water quality found has improved essentially. In spite of these monitored data no effective correlation to data from the concerning ambulant sector of medical care could be established. The Carinthian Sentinel Practice Network started in summer 1994 to retrieve informations about occurrence and frequency of bathing related illness of children up to 16 years old. The 26 participating primary health care and pediatric physicians, having their own independent practices spread all over the country, reported the specific doctor-patient-contracts to the coordinating base. Criteria for inclusion in the medical report were headache, sore throat, otalgia, stomach-ache, nausea, emesis, diarrhoea, fever, rhinitis, cough, cold, moreover conjunctivitis, skin rash and specific dermatitis. In addition physicians reported where, how long and how often the children had been bathing and how long they had been free of symptoms afterwards. Each case was reported to the coordinating base including a presumed diagnosis. Statistic evaluation showed that bathing related illness may be divided into three main groups according to symptom frequency. The frequency of otalgia (32.4%) was significantly higher than any other symptom asked for. Two groups of symptoms correlate with each other: on one hand rhinitis, conjunctivitis, cough and sore throat (36.5%) and on the other hand nausea, emesis, diarrhoea and fever (41.9%). These data underline conclusions drawn by other authors but are not representative enough to correlate to data from water monitoring. First results suggest that conclusions for public health authorities can be drawn from this additional information about the state of the lakes and ponds-providing a sufficient number of data is reported.

Adolescent↗