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Biomedical subjects

M Scheer

Publications and source records attributed to M Scheer.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Current status and prospects of chemoprevention in oral squamous epithelial carcinomas and precancerous lesions].

Second primary tumors in initially cured patients remain the greatest challenge in therapy for oral squamous cell carcinomas. The concept of field concerization is the most accepted hypothesis for the cellular and subcellular damages resulting in neoplastic transformation in the upper aerodigestive tract by risk factors such as chronic alcohol and tobacco abuse. Recent studies investigated several agents and regimens with benefit for chemoprevention of oral squamous cell carcinomas. In our review, the results of the most promising agents were studied. Despite discouraging results from recent intervention trials, studies in oral squamous cell carcinomas reported response rates up to 92%. In our investigation, two groups of patients were treated daily with 100 mg alpha-tocopherol, 75 mg beta-carotene, and 1000 mg ascorbic acid per os. The first group consisted of 24 patients with leukoplakia of the oral cavity. The second group included 24 patients with premalignant lesions after R0-resection of primary oral squamous cell carcinoma. Biopsies were taken from both groups prior to therapy and after 12 weeks follow-up. Flow cytometry analyses were performed and nucleolar organizing regions (NOR) were examined. An overall histological response rate of nearly 98% was noticed. Additionally, the pretherapeutic regimen increased cell kinetic parameters, such as the S-phase portion, and the average number of NOR per cell nucleus decreased. These results indicate that the chosen combination has substantial activity in oral premalignant lesions. Nevertheless, basic research is required in investigating valid biomarkers for chemoprevention studies.

Anticarcinogenic Agents↗
PubMed2000

Alternative or additional diagnoses on unenhanced helical computed tomography for suspected renal colic: experience with 1000 consecutive examinations.

OBJECTIVES: To determine the incidence and spectrum of significant alternative or additional diagnoses established or suggested on unenhanced helical computed tomography (CT) in a large series of patients with suspected renal colic. METHODS: One thousand consecutive unenhanced helical CT examinations were performed for suspected renal colic. All official CT reports were retrospectively reviewed, which was followed by review of all available relevant follow-up radiology reports. A selected image and chart review was also performed. RESULTS: Ureteral calculi were identified on 557 examinations, findings consistent with a recently passed stone were discovered on 67 examinations, and 275 CT examinations were unremarkable. An alternative or additional diagnosis was established or suggested on 101 examinations, including in 26 patients with concurrent ureteral calculi. There were 62 genitourinary and 39 nongenitourinary tract diagnoses. Eighty-seven of the diagnoses could be confirmed on retrospective image review combined with patient follow-up. There were two false-positive diagnoses for significant, alternative pathologic findings. CONCLUSIONS: A wide spectrum of significant, alternative, and additional genitourinary and nongenitourinary diagnoses can be reliably established or suggested on unenhanced helical CT performed for suspected renal colic. These abnormalities were identified in 10% of cases in this series of 1000 consecutive CT examinations.

Adult↗
PubMed1999

Transition Metal Induced Pentamerization of a Phosphaalkyne.

The metalla-norbornadiene complex 1, extended by two phosphaalkyne units in the 1,4-position, is formed by an unprecedented pentamerization of the phosphaalkyne MesC identical withP (Mes=2,4,6-Me(3)C(6)H(2)) in the coordination sphere of the transition metal complex [W(CO)(5)(thf)].

Journal Article↗
PubMed1998

Insertion devices for BESSY II.

The high-brilliance synchrotron radiation source BESSY II will provide space for the installation of 14 insertion devices. At the time of writing (July 1997), eight insertion devices are funded. The first light for use by scientists will be available in January 1999. The undulators are designed for a scanning operation in parallel with the monochromator. This modus requires tight tolerances concerning the drive system. The first insertion device to be installed, a U-49 undulator, has been assembled and magnetically measured. The r.m.s. phase error is 2 degrees. An endpole configuration using coils with less than 64 amp-turns makes the angular kick smaller than +/-3 micro rad over a gap range 15-50 mm.

Journal Article↗
PubMed1998

A plane-grating monochromator for circularly polarized undulator radiation at BESSY II.

At BESSY II, a third-generation 1.7 GeV storage ring is under construction. A planar elliptical undulator will be installed as a source of X-rays that have a high degree of circular polarization. Radiation in the first, third and fifth harmonics will cover the energy range 87-1330 eV. The beamline will essentially consist of a plane-grating monochromator working with collimated light in the dispersion plane. A single set of optical elements can be used to handle the two angularly separated beams of opposite helicity from the double undulator. The degree of circular polarization ranges from 73 to 100%, and a flux of up to 5 x 10(13) photons s(-1) (100 mA)(-1) can be achieved. A maximum spectral resolution of about 13 000 will be possible at 100 eV using a 20 micro m slit.

Journal Article↗
PubMed1998

Recurrent chromosomal imbalances detected in biopsy material from oral premalignant and malignant lesions by combined tissue microdissection, universal DNA amplification, and comparative genomic hybridization.

Biopsies routinely performed for the histopathological diagnosis of oral epithelial lesions before treatment were screened for chromosomal imbalances by comparative genomic hybridization. Comparative genomic hybridization was performed on 12 oral premalignant lesions (OPLs; dysplasias and carcinomas in situ) and 14 oral squamous cell carcinomas (OSCCs). Eight biopsies displayed areas of different histopathological appearance, so that OPLs and OSCCs from the same patient were analyzed. To avoid contamination with nonneoplastic cells, defined cell populations were isolated by micromanipulation with a glass needle. Before comparative genomic hybridization analysis, universal DNA amplification was performed using the DOP-polymerase chain reaction protocol. In the 14 OSCCs examined, the average number of chromosomal imbalances was significantly higher than in the 12 OPLs (mean +/- SEM: 11.9 +/- 1.9 versus 3.2 +/- 1.2; P = 0.003). The DNA copy number changes identified in more than one OPL were gains on 8q (3 of 12) and 16p (2 of 12), as well as losses on 3p (5 of 12); 5q (4 of 12); 13q (3 of 12); and 4q, 8p, and 9p (2 of 12 each). In more than 30% of OSCCs, gains of chromosomal material were identified on 20q (8 of 14); 8q, 11q, 22q (7 of 14 each); 3q, 15q, and 17p (6 of 14 each); and 14q, 17q, and 20p (5 of 14 each), and losses were identified on 3p and 4q (9 of 14 each), 5q (7 of 14), 13q (6 of 14), and 2q and 9p (5 of 14 each). These results were validated by positive and negative control comparative genomic hybridization experiments and microsatellite analysis for the detection of allelic loss. The vast majority of genomic alterations found in OPLs were again identified in OSCCs from the same biopsy, supporting the hypothesis that multiple lesions in the same patient are clonally related. In summary, we show that comprehensive information on the genomic alterations in oral epithelial lesions can be obtained from small biopsies. Such data may identify prognostic indicators that could eventually assist in designing therapeutic strategies.

Adult↗
PubMed1997

[Observations on resistance monitoring in animal health].

This article describes conventional procedures which are used for susceptibility testing of bacteria isolated from food producing animals against anti-infective substances. Interpretation of results obtained from the different test methods and the conditions necessary to conduct these tests in view of a meaningful resistance monitoring are discussed. Currently, published data about the resistance situation in veterinary medicine are either not representative or have been determined under suboptimal conditions. In view of the public and often non-scientifically based discussion about bacterial resistance it is absolutely necessary to generate a scientifically valid database.

Animal Husbandry↗
PubMed1986

[Comparison of the computed tomographic changes and the clinical course following the irradiation of intracranial tumors and metastases].

The authors compared the clinical courses and the CT courses recorded at the same time in patients with primary or secondary cerebral tumors. 69 patients improved their neurologic state under external radiotherapy, 35 patients remained unchanged, and 8 patients had a deteriorated condition. The changes in computed tomography and the modifications of the clinical state of patients corresponded only in 55% of all cases. The reasons are discussed. Some patients suffered from fatigue and weak concentration about three months after the end of radiotherapy, in some cases even the neurologic state was deteriorated. These manifestations known as "early delayed reaction" were reversible.

Astrocytoma↗
PubMed1986

[Reversible computed tomographic changes following brain tumor irradiation induced by the "early-delayed reaction" after radiation].

We analyzed the incidence, timing and appearance of reversible CT findings in 55 patients undergoing radiation therapy (dose 60 Gy) for brain tumors. Three patients had "early delayed reactions" within three months of irradiation. CT studies showed increased size of the central zone of necrosis with contrast enhancement in the form of rings or garlands. Differentiation between these findings and recurrence of tumor was possible only through follow-up studies.

Adult↗
PubMed1980

[Pharmacokinetic and clinical studies with sisomicin in paediatrics (author's transl)].

Pharmakokinetic and clinical investigations were carried out with sisomicin, one of the newer aminoglycoside antibiotics, in 40 children aged from seven days to ten years. Serum concentrations were determined in 35 children 1/2, 1, 2, 4 and 6 hours after i. m. injection of 1.0 mg sisomicin/kg body weight. The average peak serum levels were 2.48 mg/l in children under three months and 3.58 mg/l in children between seven months and ten years. Renal elimination in newborns is delayed in comparison to older infants and children; the distribution volume of the central compartment diminishes with increasing age. The effect of these two counteracting tendencies is that renal clearance remains constant in the age groups investigated, however the frequency of drug administration must be adjusted according to age. During an average treatment period of ten days adequate serum concentrations between 3.1 mg/l and 6.2 mg/l one hour after injection could be achieved with dosages adjusted to age and body weight. Clinical results were good: 18 out of 20 children could be cured clinically, and 20 out of 21 isolated infectious agents were eliminated. There were no problems in local and systemic tolerance.

Bacterial Infections↗
PubMed1978

Binding of sisomicin and streptomycin to human albumin.

The aminoglycosides of the kanamycin and neomycin series are displaced from their protein binding by very low Ca++ ion concentrations, whereas streptomycin is displaced only by very high Ca++ ion concentrations. For streptomycin, therefore, the binding mechanism must differ from that for the other aminoglycosides. The displacing reaction cannot be described by the law of mass action, combining the binding equations. Several possible reasons, such as complex formation and changes in the conformation of albumin, are discussed. Complex formation between sisomicin and the lanthanide ion Nd+++, which has the same ionic radius as the Ca++ ion, could be excluded by recording the difference absorption spectrum. The displacement of the aminoglycosides from their protein binding by Ca++ ions (as well as the pH dependence of the protein binding) suggests that ionic bonds are involved in the interactions between aminoglycosides and serum proteins.

Calcium↗