Search PubMed⌕ Search

Biomedical subjects

D Schmidt

Publications and source records attributed to D Schmidt.

At least 343 records · Page 19Linked to original sources
PubMed1993

Horizontal and vertical reading: a comparative investigation of eye movements.

Electronystagmographic (ENG) recordings of eye movements were made during the horizontal and vertical reading of a standardized text. The text was rotated to one side through an angle of 90 degrees for vertical reading. A total of 35 normal subjects was investigated under identical conditions. The following differences were found: A "staircase" pattern of successive, remarkably regular eye jerks was observed during horizontal reading. The reading speed was significantly higher in the horizontal direction. Vertical eye movements during vertical reading were less regular and showed a greater number of small jerks of varying size. No significant difference in reading speed between the two vertical directions was found. The search coil method (Robinson), which was employed in one subject, yielded much more accurate recordings than did the ENG. As a control experiment for vertical reading, the letters were rotated through 90 degrees. Reading this transposed text took twice as long as reading a 90 degrees-rotated text.

Adult↗
PubMed1993

[Ocular tissue after intravitreous silicone oil injection. Histologic and electron microscopy studies].

The intraocular tolerance of silicone oil is still a matter of ongoing controversy. To evaluate a possible migration of silicone oil into eye tissues we examined various tissues from eyes that were injected with silicone oil for a period of 6 months to 3.5 years. The histological and ultrastructural characteristics of these tissues are reported (cornea, 4 cases; iris, 3 cases; retina, 8 cases; retinal pigment epithelium and optic nerve, 1 case). In the iris and in corneas showing a perforating injury light microscopy revealed vacuoles presumably lying in the cytoplasm of macrophages. Using immunohistochemistry and electron microscopy, macrophages could also be found in the retina of eyes that had been filled with silicone oil for longer than 6 months. Using energy dispersive X-ray analysis, vacuoles could be identified as storage sites of the silicone oil. This observation demonstrates that a long-term silicone oil tamponade may cause a migration of silicone oil into the retina and other ocular tissues. In order to prevent this complication, removal of silicone oil should be performed as early as possible.

Choroid↗
PubMed1993

[A comparison of digital radiography and conventional x-ray diagnosis for shoulder arthrography].

Fifty double-contrast arthrographies of the shoulder were obtained using conventional film-screen methods as well as by digital luminescence radiography (DLR). The supplied picture-evaluation programs had to be modified and improved prior to this study. In DLR two different post-processed images were obtained, one resembling a conventional film-screen, the other with an intensified edge-enhancement. Some of the digital luminescence radiographs were exposed with only 50% of the conventional doses. A comparison showed the equivalent diagnostic values of both the improved DLR and the conventional film screen. Even a reduction of the exposure dosage did not lead to a loss of information.

Adult↗
PubMed1992

[Pheochromocytoma as dominant manifestation of v. Hippel-Lindau syndrome].

A diagnosis of von Hippel-Lindau syndrome was made in two families originating from the same part of the Black Forest but apparently unrelated. Nine affected persons (seven males and two females) had a total of 17 tumours: retinal angioma (4), haemangioblastoma of the CNS (1), and phaeochromocytoma (12). Three of the affected persons and eight of the tumours (six phaeochromocytomas, two retinal angiomas) were diagnosed by family screening. Phaeochromocytoma was diagnosed in eight persons; in four it was the only symptomatic lesion. After extensive diagnostic tests the phaeochromocytoma was the sole tumour in four. Despite severe symptoms the diagnosis of von Hippel-Lindau syndrome had not been made prior to the screening examinations because either the common aetiology of the tumour was not known or there was insufficient exchange of information between the two families.--It is recommended that in each case of phaeochromocytoma von Hippel-Lindau syndrome should be excluded so that lesions can be discovered early in other organs and in other affected family members. If the syndrome is present, annual examinations are indicated because of asynchronous and multi-focal tumour growth.

Adolescent↗
PubMed1992

Microcatheter urokinase infusion in central retinal artery occlusion.

We treated 14 consecutive patients for acute central retinal artery occlusion. Eleven were treated with urokinase introduced through a microcatheter in the proximal segment of the ophthalmic artery. Fibrinolysis was succeeded by heparinization for two to three days. Instead of urokinase, we used tissue plasminogen activator in three patients. Vision improved markedly in four of the 14 patients. Five others had slight improvement of visual acuity, visual field, or both. In five patients, no change occurred. Such a recovery of visual acuity may be anticipated if treatment begins within the first few hours after the onset of central retinal artery occlusion. A control group of 41 consecutive patients treated conservatively showed almost no improvement in visual acuity. Eleven of these 41 patients were treated within the first six hours after the patient noticed the onset of blindness.

Acute Disease↗
PubMed1992

Activation state of the cortex could be changed by reinforcement of low-amplitude visual evoked potentials in rabbits.

Visually evoked potentials (VEP) were recorded chronically from occipital cortex in awake rabbits. The VEP typically consisted of a triphasic response (positive deflection P60--negative deflection N205--positive deflection P450) that was followed by a late negative shift starting about 750 ms after the eliciting flash. After computation of a discriminating amplitude value (200 or 250 microV) the VEP were divided for comparison in high- and low-amplitude groups. Significant differences between these groups existed in amplitudes and latencies of the early VEP components. High-amplitude VEP were followed by larger late negative shifts and had significantly (P less than 0.01) earlier second positive deflections. In these high-amplitude cases, the EEG-baseline was more negative than in the low-amplitude VEP. In addition, we found a more synchronized background EEG in the low-amplitude VEP group. We conclude that different VEP amplitudes depended on different activation states of the cortex which could be changed by reinforcement.

Animals↗
PubMed1992

Spinal canal metastases: a late complication of glioblastoma.

The case of a 41 year old woman with a cerebral glioblastoma is reported who developed paraplegia due to a pathologically confirmed spinal metastasis. This and 22 other case histories from the literature suggest that spinal seeding is a rather late complication of cerebral glioblastomas that can be diagnosed on clinical grounds with the help of myelography, CSF cytology and MR imaging.

Adult↗
PubMed1992

Maternal serum alpha-fetoprotein, beta-human chorionic gonadotropin, and unconjugated estriol levels in midtrimester trisomy 18 pregnancies.

OBJECTIVE: The purpose was to evaluate the levels of maternal serum human chorionic gonadotropin, alpha-fetoprotein, and unconjugated estriol in trisomy 18 pregnancies compared with normal singleton pregnancies. STUDY DESIGN: Sera from 14 trisomy 18 pregnancies (13 retrospectively and one prospectively ascertained) were analyzed for human chorionic gonadotropin, alpha-fetoprotein, and unconjugated estriol. RESULTS: The alpha-fetoprotein levels in the 10 trisomy 18 pregnancies without open neural tube or ventral wall defect had a median of 0.65 multiple of the median, although two had alpha-fetoprotein levels above 2.5 multiples of the median. The human chorionic gonadotropin levels had a median of 0.32 multiple of the median and the unconjugated estriol levels had a median of 0.56 multiple of the median. Although most women with trisomy 18 pregnancies had serum human chorionic gonadotropin levels that were less than 1.0 multiple of the median, three had markedly elevated human chorionic gonadotropin levels (greater than 5.0 multiples of the median). CONCLUSION: Our data are partially consistent with those previously published but suggest the possibility of a bimodal distribution of alpha-fetoprotein and human chorionic gonadotropin levels in trisomy 18-affected pregnancies, unrelated to a neural tube or abdominal wall defect. The efficiency of screening for trisomy 18 prospectively, using the three serum markers, requires further evaluation.

Adult↗
PubMed1992

Malignant renal tumors of childhood.

The prognosis in nephroblastoma (Wilms' tumor) has been improved considerably by treatment protocols combining surgery, chemotherapy, radiation therapy, and, in some clinical trials, pre-operative chemotherapy. Cure is now achieved in most patients. All clinical trials have employed treatment strategies tailored to the individual risk of the patient, including the histological subtype of the tumor. In the National Wilms' Tumor Study (NWTS) of the United States these subtypes have been divided into two groups of tumors according to their "favorable" or "unfavorable" histology. At the Kiel Pediatric Tumor Registry we have devised a system which distinguishes three groups of tumors classified according to prognosis. The first group includes tumors with a favorable prognosis, even if only surgery is performed. These comprise congenital mesoblastic nephroma (CMN) and cystic, partially differentiated nephroblastoma (CPDN). The second group consists of tumors posing an intermediate risk, such as typical nephroblastoma and its histological variants characterized by variations in the relative proportions of the histological components. Fetal rhabdomyomatous nephroblastoma (FRN) is also included in this group. The third group comprises tumors of high risk such as anaplastic nephroblastoma, clear cell sarcoma of the kidney (CCSK), and malignant rhabdoid tumor of the kidney (MRTK). Since histological diagnosis plays a crucial role in the assignment of a patient to a particular type of treatment protocol, knowledge of the histological appearance of the various tumor types both with and without preoperative treatment is of utmost importance.

Antineoplastic Agents↗
PubMed1992

Spindle cell rhabdomyosarcoma. A prognostically favorable variant of rhabdomyosarcoma.

Twenty-one cases of embryonal rhabdomyosarcoma, composed mainly of elongated spindle cells arranged in a fasciculated or storiform pattern, were retrieved from the files of the German-Italian Cooperative Soft Tissue Sarcoma Study. The term spindle cell rhabdomyosarcoma is proposed to designate this histotype. Spindle cell rhabdomyosarcoma predilected male patients (18 males, three females) and involved mostly the paratesticular area (12 cases) and the head and neck region (six cases). Histologically, all cases were characterized by a uniform proliferation of elongated spindle cells with eosinophilic and fibrillar cytoplasm mimicking smooth muscle fibers; immunocytochemical studies disclosed high expression of the muscle markers titin, desmin, and myoglobin. Clinical information was available in 17 cases; according to the Intergroup Rhabdomyosarcoma Study (IRS) grouping system, 13 were classified in group I, two in group II, and two in group III. Sixteen patients were well and alive 24 to 100 months after diagnosis; one patient died from disease progression 24 months after diagnosis. Analysis of our results determined that spindle cell rhabdomyosarcoma constitutes a rare variant of the embryonal form, showing a high degree of skeletal muscle differentiation and a low malignant potential; it should therefore be distinguished from classical forms of embryonal rhabdomyosarcoma.

Adolescent↗
PubMed1992

Identification of silicone oil in the retina after intravitreal injection.

Retinal tissue obtained from 2 eyes that had been injected with silicone oil for 2 years was stained with monoclonal antibodies against macrophages and studied by light and electron microscopy and energy-dispersive x-ray analysis. Both specimens showed areas with a relatively intact architecture as well as parts with loss of normal structure. In both areas, immunostaining showed single intraretinal macrophages. Energy-dispersive x-ray results clearly demonstrated that some of the intracellular and extracellular vacuoles within the retina represented the storage sites of silicone.

Adult↗
PubMed1992

Production of an electrolyte beverage from milk permeate.

The objective of this study was to prepare shelf-stable electrolyte beverages from milk permeate. The average composition of permeate was 4.59% total solids and .40% ash. Lactose was hydrolyzed (approximately 80%) with a commercial fungal lactase enzyme. Additional sweetness was provided by sucrose. The pH was reduced to 3.5 to 3.8 by the addition of citric acid. Shelf-stable products were made using four processes: 1) UHT followed by aseptic filling, 2) heating of filled bottles to 85 degrees C for 30 min, 3) addition of .05% benzoate, and 4) nanopore filtration. The mineral composition of the finished product, expressed in parts per million, was calcium, 150; phosphorus, 157; magnesium, 43; potassium, 1166; sodium, 286; iron, 17; copper, 8; and zinc, 3.4. Listeria monocytogenes, Salmonella dublin, Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae grew well when they were inoculated into unacidified, hydrolyzed permeate. None of these organisms were isolated from properly processed products. A shelf-stable electrolyte beverage high in minerals was made from whole milk permeate. This beverage could be used to replace electrolytes lost from the human body. The production of a permeate beverage would help alleviate disposal problems of permeate.

Animals↗
PubMed1992

[Rhabdomyosarcoma: differential diagnosis of cutaneous tumors in childhood].

Primary rhabdomyosarcoma can arise in the skin, but there are few reports on this common childhood malignancy in the dermatological literature. We report on a male infant with a cutaneous tumour growing on the right nasal bridge since his 10th week of life. Clinically the tumour mimicked pilomatrixoma. Histological and immunohistological examination of the skin tumour and of subsequent lymph node metastases revealed rhabdomyosarcoma of the alveolar growth pattern. Our patient died at the age of 4 years of disseminated organ metastases.

Biomarkers, Tumor↗