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Biomedical subjects

C Mohr

Publications and source records attributed to C Mohr.

At least 91 records · Page 5Linked to original sources
PubMed1991

Interaction of mastoparan with the low molecular mass GTP-binding proteins rho/rac.

Mastoparan, which has been shown to active G proteins, inhibits the ADP-ribosylation of 20 kDa human platelet membrane proteins catalyzed by Clostridium botulinum exoenzyme C3 half-maximally and maximally (90%) at 20 and 100 microM concentrations, respectively. Inhibition of ADP-ribosylation was enhanced by GTP-gamma S. Mastoparan increased GTP hydrolysis by porcine brain rho protein and stimulated GTP binding in a concentration dependent manner. The data suggest that mastoparan not only interacts with heterotrimeric G proteins but also with low molecular mass GTP-binding proteins of the rho/rac family.

ADP Ribose Transferases↗
PubMed1991

ADP-ribosylation and de-ADP-ribosylation of the rho protein by Clostridium botulinum exoenzyme C3. Regulation by EDTA, guanine nucleotides and pH.

Pretreatment of rho protein purified from pig brain cytosol with EDTA (3 mM) for 10 min at 30 degrees C inhibited its ADP-ribosylation by Clostridium botulinum C3 ADP-ribosyltransferase by more than 90%. The EDTA effect was not caused by alteration of C3. GDP or GDP beta S present during the pretreatment period completely prevented the decrease in ADP-ribosylation with half-maximal and maximal effects at 3 and 300 microM, respectively. GTP or GTP gamma S were less efficacious in preventing the decrease in ADP-ribosylation, but were more potent (half-maximal and maximal effects at 0.1 and 3 microM, respectively). [32P]ADP-ribose incorporated in pig brain rho by C3 was de-ADP-ribosylated by the enzyme in the presence of nicotinamide and at low pH. Concomitantly, [32P]NAD was formed. The pH optima for ADP-ribosylation and de-ADP-ribosylation were pH 7.5 and 5.5, respectively. De-ADP-ribosylation was most efficient with nicotinamide, less effective with 3-acetylpyridine and not observed with 3-aminopyridine, 4-aminopyridine, 4-acetylpyridine and isonicotinic acid. As observed for the ADP-ribosylation, the de-ADP-ribosylation by C3 was maximal with the GDP-bound form of rho and blocked after EDTA treatment.

ADP Ribose Transferases↗
PubMed1991

Long-term treatment effects in patients with bilateral retinoblastoma: ocular and mid-facial findings.

A total of 99 patients with bilateral retinoblastoma who had been treated between 1965 and 1982 were reexamined in April 1988 to study the late effects of treatment. Their median age at the follow-up visit in 1988 was 16 years (range, 6-27 years), and the median follow-up was 15 years (range, 6-26 years). All patients underwent a full eye examination, morphometric measurements of the mid-face and genetic counselling. Each eye or orbit and the corresponding side of the patient's mid-face were evaluated separately, resulting in 198 data sets from 99 individuals. Subjects were divided into four treatment groups according to whether photo- and cryo-coagulation, enucleation, radiation therapy or various combinations thereof were used. In all, 81 eyes had a visual acuity of greater than 0.4 (in 23 of these, however, only with low-vision aids). Within a dose range of 36-51 Gy, the location of the tumor (36%) or cataract (15%) were the main factors responsible for poor visual acuity, whereas radiation retinopathy and/or optic neuropathy occurred in only three cases. Cataracts were more frequently observed following orthovoltage as compared with megavoltage therapy (P = 0.012). A total of 72 eyes had been enucleated and had not received radiation therapy at any time. Cosmetic results (as measured by several parameters) in these cases were significantly better then those in 28 subjects who underwent combined radiation therapy and enucleation. As defined by various subjective as well as objective findings, mid-facial hypoplasia occurred significantly more often following orthovoltage as compared with megavoltage therapy.

Adolescent↗
PubMed1991

Symbiotic interactions between colonic microflora and protein metabolism in infants.

The utilization of 15N nitrogen from 15N-labelled bifidobacteria for whole body protein synthesis was studied in 4 infants by oral single-pulse labellings and in 3 other infants, who had colostomies, by colonic pulse labellings. The bifidobacteria were harvested from a modified Petuely culture medium containing 15N ammonium chloride and 15N cystine as the only sources of nitrogen. The tracer dose chosen for the balance studies was 3 mg 15N/kg. 15N concentrations in urine and feces collected over 48 hours after the pulse labellings were determined by emission spectrometry. Oral administration of 15N-labelled bifidobacteria resulted in absorption of approximately 90% renal excretion of 15%, and fecal excretion of 12% of the tracer dose, respectively. Retention in the protein pool averaged 73%. After colonic single pulse labelling with 15N-labelled bifidobacteria, the corresponding values were 85.5%, 2.2%, 14.5% and 83.0%, respectively. Absorption and incorporation of the heavy nitrogen into body proteins were directly demonstrated by increased 15N atom percent excess values within the trichloroacetic acid (TCA) supernatants and the proteins of the plasma, 0.25 and 0.04 atom%, respectively, at 24 hours after oral pulse labellings. One half of the total 15N excreted in urine consisted of urea and approximately 8% was eliminated as ammonia.

Bifidobacterium↗
PubMed1991

Systemic macrophage stimulation in rats with silicosis: enhanced release of tumor necrosis factor-alpha from alveolar and peritoneal macrophages.

In silicosis, alveolar macrophages (AM) are thought to induce chronic inflammation and fibrosis by release of cytokines. Rats were exposed to aerosols of alpha-quartz and examined 4 to 9 mo later for persistence of silica particles and release of tumor necrosis factor-alpha (TNF-alpha) from macrophages. Silica particles were detected in AM, lung parenchyma, and thoracic lymphoid organs, whereas extrathoracic lymphoid tissues and organs were free of the mineral. When AM were tested functionally, no spontaneous release of TNF-alpha was observed. However, upon in vitro stimulation of AM from silicotic rats with a low concentration of lipopolysaccharide (10 ng/ml), abundant TNF-alpha production was found that was higher and occurred more rapidly than with AM from sham-exposed animals. Peritoneal macrophages, which did not have contact with silica particles, displayed a similarly enhanced TNF-alpha release in response to low doses of lipopolysaccharide. These data demonstrate a state of systemic preactivation ("priming") of macrophages that supports the notion that silicosis is associated with a general immunostimulation.

Animals↗
PubMed1991

[Development of postoperative motility in orbital floor, zygomatic and mid-face fractures].

A prospective study of was made on 100 patients with fractures of the orbital floor, the zygoma and/or midface who were surgically treated and investigated (before and 3 days, 7 days, 1 month and 6 months after surgery) with regard to their eye motility (Hess screen) and their double vision (Harms tangent screen). Stable results were obtained at least 30 days after surgery. Patients in whom early surgery was performed (within 7 days after trauma) showed better results (82% improvement) compared with those operated on in the second week after the trauma (50% improvement) or later (27% improvement). Young patients (less than 10 years of age) and patients with midface fractures (LeFort II and III) showed significantly poorer results with regard to eye motility.

Adolescent↗
PubMed1990

Morphological alterations of Xenopus oocytes induced by valine-14 p21rho depend on isoprenylation and are inhibited by Clostridium botulinum C3 ADP-ribosyltransferase.

Microinjection of the constitutively active recombinant Val-14 p21rho A into Xenopus oocytes induced dramatic morphological changes with redistribution of pigments from the animal pole resulting in spotted oocytes. The effects induced by Val-14 p21rho A were regulated by progesterone in a dose-dependent manner whereas prior ADP-ribosylation of the rho protein blocked its activity. About 30 min after microinjection, p21 rho was associated with the plasma membrane. The membrane association of p21rho and its biological activity were inhibited by lovastatin, an inhibitor of the 3-hydroxy-3-methylglutaryl coenzyme A reductase. The findings suggest that membrane attachment and biological activity of p21rho depend on isoprenylation of the GTP-binding protein.

ADP Ribose Transferases↗
PubMed1990

Microinjection of alpha-toxin from Clostridium novyi type A promotes meiotic maturation in Xenopus laevis oocytes.

Microinjection of purified alpha-toxin into Xenopus laevis oocytes induced meiotic maturation provided insulin was present in the medium. Induction of maturation as indicated by breakdown of the germinal vesicle depended on the amount of intracellular alpha-toxin (with a detection limit of 2 ng/oocyte) and on the concentration of insulin. The hormone concentrations used were inactive when given alone and so was alpha-toxin (1 micrograms/ml) applied from the outside. The results demonstrate an intracellular target for alpha-toxin whereas an extracellular target is apparently lacking in oocytes.

Animals↗
PubMed1990

[Indications for the surgical treatment of midfacial fractures in children].

A study of midfacial fractures in 28 children under 16 years of age treated at the Medical School Essen is reported. All children underwent surgical treatment. 18 patients with fractures of the zygomatic complex were treated by open reduction and miniplate osteosynthesis. 10 patients with blowout fractures were treated with "Lyodura"-implants. To prevent persistent diplopia an early surgical treatment is recommended. An adverse effect on the growth of facial bones has not been seen.

Adolescent↗
PubMed1989

The surgical approach to orbital space-occupying lesions.

From January 1985 to April 1987, 60 patients with orbital space-occupying lesions were treated surgically. Orientation and spatial localization of the lesion had already been achieved preoperatively by means of imaging methods. The decision on whether to use a neurosurgical transcranial, or a facial surgical approach, was made on this basis. The less elaborate procedure in each case was given preference to obtain a representative tissue sample. The definitive planning of the operation was then carried out with knowledge of the histology: a transcranial operation alone or as an additional measure was only necessary in six patients. Either definitive tumour therapy could be performed with or without temporal osteotomy in the remaining 54 patients exclusively via an anterior orbitotomy, or further oncological treatment was commenced after histological verification of the diagnosis.

Humans↗
PubMed1988

Choice of surgical approach in orbital space occupations--an interdisciplinary problem.

During the last two and a half years 60 patients with orbital space occupying neoplasms were treated surgically at the Department of Maxillo-facial Surgery of the University Clinic of Essen. With modern imaging techniques exact information on the location and extent of space occupation was available before the operation. Therefore the surgical approach could be optimized. Despite the various and sometimes inaccessible tumor locations, transcranial operation was only necessary in six patients. In the remaining 54 patients anterior orbitotomy allowed either a definitive tumor therapy or histological verification of the diagnosis.

Hemangioma↗
PubMed1988

[Granular cell tumor of the orbit].

The authors report on the rare case of the intraorbital localisation of a granular cell tumour. Nature, histogenesis and biological behaviour of this lesion are discussed. The therapeutical consequences are presented.

Adult↗