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H Gruber

Publications and source records attributed to H Gruber.

At least 55 records · Page 3Linked to original sources
PubMed1996

Age-related changes in osteogenic stem cells in mice.

Osteoblasts arise from partially differentiated osteogenic progenitor cells (OPCs) which in turn arise from undifferentiated marrow stromal mesenchymal stem cells (MSCs). It has been postulated that age-related defects in osteoblast number and function may be due to quantitative and qualitative stem cell defects. To examine this possibility, we compared osteogenic stem cell number and in vitro function in marrow cells from 4-month-old and 24-month-old male BALB/c mice. Histologic studies demonstrated that these mice undergo age-related bone loss resembling that seen in humans. In primary MSC cultures grown in media supplemented with 10 nM dexamethasone, cultures from older animals yielded an average of 41% fewer OPC colonies per given number of marrow cells plated (p < 0.001). This implies that for a given number of marrow cells there are fewer stem cells with osteogenic potential in older animals than there are in younger animals. The basal proliferative rate in cultures from older animals, as measured by 3H-thymidine uptake, was more than three times that observed in cultures from young animals (p < 0.005). However, the increase in proliferative response to serum stimulation was 10-fold in the younger cultures (p <0.001) and insignificant (p <0.4) in the older cultures. Colonies in both age groups became alkaline phosphatase positive at the same rate, and virtually all colonies were positive after 12 days of culture. Cultures from both age groups produced abundant type I collagen. These studies suggest that defects in the number and proliferative potential of MSCs may underlie age-related defects in osteoblast number and function.

Aging↗
PubMed1996

Expression of the Volvox gene encoding nitrate reductase: mutation-dependent activation of cryptic splice sites and intron-enhanced gene expression from a cDNA.

Use of the nitrate reductase encoding gene (nitA) as selection marker has facilitated the successful nuclear transformation of Volvox carteri. The Volvox nitA gene contains 10 introns. A stable nitA mutation in the Volvox recipient strain 153-81 resides in a G-to-A transition of the first nucleotide in the 5' splice site of nitA intron 2. This mutation resulted in at least three non-functional splice variants, namely: (1) intron 2 was not spliced at all; (2) a cryptic 5' splice site 60 nt upstream or (3) a cryptic 5' splice site 16 nt downstream of the mutation were activated and used for splicing. When we used nitA cDNA (pVcNR13) for transformation of V. carteri 153-81, a low efficiency of about 5 x 10(-5) transformants per reproductive cell was observed. Re-integration of either intron 1 (pVcNR15) or introns 9 and 10 (pVcNR16) in the transforming cDNA increased transformation rates to 5 x 10(-4). In parallel, pVcNR15-transformed Volvox exhibited growth rates that were 100-fold increased over the pVcNR13-transformed alga. This intron-enhancement of nitA gene expression appears to be associated with post-transcriptional processing and 'channelling' of the message. These data suggest an important role of splicing for gene expression in V. carteri.

Base Sequence↗
PubMed1996

[sensorimotor differentiated reconstruction of peripheral nerves--a methods of intraoperative identification of motor fascicles].

In 1975, Freilinger et al. identified motor fibres by acetylcholinesterase (AChE) histochemistry. Precise identification of motor fascicles in cases of mixed peripheral nerve dissection became possible, and selective fascicular nerve repair could be performed. Using this technique, two separate operations were necessary for definitive nerve repair, since histochemical analysis took 28 hours. A modified AChE staining technique now offers results within one hour. In seven cases of human median and three cases of human ulnar nerve lesions, nerve biopsies were obtained and underwent both modified and standard histochemical staining. The standard procedure did not render any further information about the AChE activity indicating that both methods are equally reliable. Photomicrographs of the nerve specimen with motor fascicles marked on them were completed in all cases of the modified AChE staining method one hour after obtaining the biopsies. Intraoperative identification of motor fascicles by rapid AChE staining technique was performed in two cases of acute injuries of the median nerve, radial artery and musculotendineous system of the forearm. Biopsies were obtained at the beginning of the operation. Histochemical analysis was done while tendons and arteries were reconstructed and selective fascicular nerve repair was possible at the end of the operation. The rapid AChE staining may be applied intraoperatively to acute nerve injury and late peripheral nerve reconstruction provided the nerve is expected to already contain segregated motor fascicles.

Acetylcholinesterase↗
PubMed1995

Action of calpastatin in prevention of cardiac L-type Ca2+ channel run-down cannot be mimicked by synthetic calpain inhibitors.

Activity of L-type Ca2+ channels in a membrane patch disappears rapidly when the patch is excised from the cell into an artificial solution. This channel run-down observed in isolated membrane patches can however, be prevented by application of calpastatin, an endogenous protease inhibitor, and ATP. The high specificity of calpastatin for the protease calpain would clearly point to a participation of calpain activity in the run-down of Ca2+ channels. In an attempt to examine a possible involvement of calpain, three synthetic and rather specific calpain inhibitors were substituted for calpastatin. One of these inhibitors chosen for its membrane permeability in addition allowed calpain activity to be inhibited even before patch excision. The potency of these compounds in inhibiting calpain, specifically mu- and m-calpain, was first determined in a biochemical assay and then compared with their efficacy in preventing Ca2+ channel run-down. Surprisingly, calpastatin was least effective in calpain inhibition but by far the most potent in prevention of Ca2+ channel run-down. In addition run-down of Ca2+ channel activity was examined for its reversibility, which would not be expected upon involvement of a proteolytic process. However, Ca2+ channel activity clearly recovered after run-down by application of calpastatin. In contrast, synthetic calpain inhibitors were unable to reverse Ca2+ channel run-down. These results indicate that proteolysis might only be partially responsible for channel run-down and suggest an as yet unidentified function for calpastatin beyond its inhibitory action on calpain in the regulation of Ca2+ channel activity.

Adenosine Triphosphate↗
PubMed1995

Effect of acadesine treatment on postischemic damage to small intestine.

Hemorrhagic mucosal lesions are produced during intestinal ischemia and after reperfusion due at least in part to the accumulation and activation of polymorphonuclear leukocytes in the tissue. It has been shown in vitro that adenosine is instrumental in attenuating this pathophysiological process. Acadesine [5-amino-4-imidazolecarboxamide (AICA) riboside], a purine nucleoside analogue, increases the availability of adenosine in the tissue. The aim of the study was therefore to assess the influence of acadesine treatment on neutrophil accumulation, purine metabolism, and mucosal damage after intestinal ischemia and reperfusion. Intestinal ischemia was induced in cats by partial occlusion of the superior mesenteric artery for 2 h. Samples of the small intestine were exercised before and at the end of the hypotensive period as well as 10 and 60 min after reperfusion. Conjugated dienes, myeloperoxidase, and reduced and oxidized glutathione, as well as the purine metabolites, were determined in the tissue samples. The tissue was also examined histologically. Six cats received saline, and six cats were treated initially before ischemia with acadesine (2.5 mg/kg body wt i.v.) over 5 min as a bolus. Thereafter, acadesine (0.5 mg.kg-1.min- i.v.) was given continuously during ischemia and 30 min after reperfusion. Acadesine treatment significantly attenuated the mucosal lesions seen during reperfusion. This improvement was due at least in part to the inhibition of neutrophil accumulation, as judged by low myeloperoxidase levels. The prevention of neutrophil activation resulted most likely from increased adenosine concentrations in the intestinal tissue in the early reperfusion period.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminoimidazole Carboxamide↗
PubMed1995

Acadesine reduces indium-labeled platelet deposition after photothrombosis of the common carotid artery in rats.

BACKGROUND AND PURPOSE: The adenosine-regulating agent acadesine has been shown to reduce the incidence of myocardial infarction and stroke after cardiopulmonary bypass surgery. The present study examined the effect of acadesine on the accumulation of indium-labeled platelet emboli and infarct size after photothrombosis of the common carotid artery. METHODS: Rats were anesthetized with halothane and preloaded with 111In-tropolone-labeled platelets (50 to 80 microCi) 30 minutes before nonocclusive common carotid artery thrombosis induced by a rose bengal-mediated photochemical insult. Intravenous infusion of acadesine (0.5, 1, or 2 mg/kg per minute) or vehicle was begun 30 minutes before right common carotid artery thrombosis and continued for an additional 15 minutes. Rats were then killed and brains processed for the autoradiographic quantitation of labeled platelet aggregates. In a separate group of rats, infarct areas and volumes were determined in treated (acadesine 1 mg/kg per minute) (n = 9) and nontreated (n = 9) rats 7 days after thrombosis. RESULTS: Although the ratio of right-to-left common carotid artery radioactivity was not affected by treatment, acadesine at 1 and 2 mg/kg per minute significantly decreased (P < .01) platelet deposition within the right cerebral cortex, hippocampus, and striatum. For example, within the frontoparietal cortex, numbers of platelet aggregates were 11.8 +/- 1.8 (mean +/- SEM), 6.1 +/- 1.4, 2.3 +/- 0.6, and 3.2 +/- 0.8 in rats infused with vehicle, 0.5, 1, and 2 mg/kg per minute acadesine, respectively. In addition, infarct volume was reduced by 48% in acadesine-treated (1 mg/kg per minute) rats, with a significant reduction in infarct area at the coronal level 3.7 mm anterior to bregma (P < .01). CONCLUSIONS: These results support a prophylactic role for acadesine in reducing the accumulation of platelet emboli during vascular thrombosis and subsequent brain infarction. Acadesine treatment in patients at risk for embolic stroke could potentially lead to cerebral protection.

Aminoimidazole Carboxamide↗
PubMed1995

[Indications and results of ex-vivo surgery of the kidney].

394 renal transplantations have been performed in our unit between 1974 and 1995. In all instances extra-corporal surgical procedures on the graft, its vessels and, in rare instances, on the collecting system were necessary. The surgical procedures, which took up to 90 minutes on the work-bench, ranged from repair of minor iatrogenic vascular injuries to major vascular reconstructions, in order to facilitate the subsequent implantation of the graft. During the same period work-bench surgical procedures with subsequent autotransplantation were performed in 8 patients. The indication for such a procedure was a renal cell carcinoma in 2 patients with a solitary kidney and bilateral renal cell carcinoma in 1 patient, as well as renovascular disease (renal artery stenosis, aneurysm of the renal artery) in the remaining 5 cases.

Adolescent↗
PubMed1994

Nuclear transformation of Volvox carteri.

Stable nuclear transformation of Volvox carteri was achieved using the cloned V. carteri nitA+ gene (which encodes nitrate reductase) to complement a nitA- mutation. Following bombardment of mutant cells with plasmid-coated gold particles, putative transformants able to utilize nitrate as a nitrogen source were recovered with an efficiency of approximately 2.5 x 10(5). DNA analysis indicated that the plasmid integrated into the genome, often in multiple copies, at sites other than the nitA locus. Cotransformants were recovered with a frequency of 40-80% when cells were cobombarded with a selected and an unselected marker. Thus, V. carteri becomes one of the simplest multicellular organisms that is accessible to detailed molecular studies of genes regulating cellular differentiation and morphogenesis.

Blotting, Southern↗
PubMed1993

Hydrops-ectopic calcification-moth-eaten skeletal dysplasia (Greenberg dysplasia): prenatal diagnosis and further delineation of a rare genetic disorder.

An offspring of consanguineous parents of East-Indian origin was found prenatally to have hydrops fetalis, short limb dwarfism, polydactyly and chondro-osseous changes consistent with Greenberg hydrops-ectopic calcification-moth-eaten skeletal dysplasia (HEM) dysplasia. The radiological changes include platyspondyly with multiple extra ossification centers, extraneous calcification in the ribs, sternum, pelvis, and epiphysis, and moth-eaten long bones. The histopathological changes included chondrocytes with dilated rough endoplasmic reticulum and inclusion bodies with homogeneous material of intermediate electron density. These findings further delineate the spectrum of this rare autosomal recessive skeletal dysplasia.

Abnormalities, Multiple↗
PubMed1993

Fiber regeneration in nerve grafts without connection to a target muscle: an experimental study in rabbits.

In 30 rabbits, both saphenous nerves were harvested as autografts and coapted to the branch for the rectus femoris muscle without connection to any distal target muscle. The graft from the right thigh was led to the contralateral extremity (crossover grafting). The graft on the left side remained on the same extremity (ipsilateral grafting). Animals were separated into four groups and were sacrificed 3, 6, 9, and 12 months after grafting. Specimens of the grafts and the donor motor branches were harvested for histomorphometric examination. The number of myelinated nerve fibers in the distal end of the nerve grafts was significantly increasing from 3 to 6 months after grafting and remained on a relatively constant level in the long-term groups. Three months after the first operation, greater numbers of myelinated nerve fibers were counted after ipsilateral grafting than after crossover grafting. In the long-term groups, this difference could not be observed.

Animals↗
PubMed1993

Chess expertise and memory for chess positions in children and adults.

This paper presents a replication and extension of Chi's (1978) classic study on chess expertise. A major outcome of Chi's research was that although adult novices had a better memory span than child experts, the children showed better memory for chess positions than the adults. The major goal of this study was to explore the effects of the following task characteristics on memory performance: (1) Familiarity with the constellation of chess pieces (i.e., meaningful versus random positions) and (2) familiarity with both the geometrical structure of the board and the form and color of chess pieces. The tasks presented to the four groups of subjects (i.e., child experts and novices, adult experts and novices) included memory for meaningful and random chess positions as well as memory for the location of wooden pieces of different forms on a board geometrically structured by circles, triangles, rhombuses, etc. (control task 1). Further, a digit span memory task was given (control task 2). The major assumption was that the superiority of experts should be greatest for the meaningful chess positions, somewhat reduced but still significant for the random positions, and nonsignificant for the board control task. Only age effects were expected for the digit span task. The results conformed to this pattern, showing that each type of knowledge contributed to the experts' superior memory span for chess positions.

Adolescent↗
PubMed1993

Location of the mandibular canal within the atrophic mandible.

In 43 edentulous, lower jaw halves, sections were carried out in the area between the mental foramen and the third molar. The relative changes in the location and course of the mandibular canal which are caused by atrophy were analysed. For this purpose, the mandibles were classified according to so-called residual ridge orders which describe the different stages of alveolar ridge resorption. The following findings were obtained: The distance between the mandibular canal and the lingual and buccal external border does not change in any stage of the atrophic process, i.e. it remains conspicuously constant. However, the distance between the mandibular canal and the cranial and caudal borders of the body of the mandible partly changes to a statistically highly-significant extent, the distance between the canal and the atrophic alveolar ridge being affected more strongly than that between the canal and the base of the mandible. These changes were most clearly pronounced in the area of the first molar.

Aged↗
PubMed1993

Isolation and characterization of group EF-4 bacteria from various lesions in cat, dog and badger.

Bacteria of Group EF-4 were isolated from local purulent lesions in 7 dogs and in 5 cats, from pneumonic lungs in 2 additional cats and from internal organs in a badger. Results of characterization were compared with those of a human strain of Group EF-4a isolated from an infected dog-bite wound. Lungs of 2 necropsied cats showed a severe focal necrotizing pneumonia in the various lobes. Organs of the badger were typical for a case of septicemia. The organisms were isolated mostly in pure culture. Colonies were up to 1.5 mm in size, round, entire, more or less yellowish pigmented and non hemolytic. Culture smelled slightly like popcorn. In conventional biochemical tests, 12 isolates as well as the human strain were shown to belong to Group EF-4a and the 3 remaining strains to EF-4b. Belonging to Group EF-4 was confirmed by assimilation tests with the gallery ATB 32 GN of BioMerieux. However some differences to other reports were observed when compared with results obtained with similar methods. Results of this study seem to indicate that bacteria of Group EF-4 are important in veterinary medicine not only from an epidemiological but also from an etiological point of view.

Animals↗
PubMed1993

[Relations between donor nerve size and degree of neurotization in the nerve transplant--an experimental study].

The present study was undertaken to investigate whether the number of myelinated fibers in a sensory nerve used as an autograft influences the result of nerve fiber regeneration in the graft. In 30 rabbits, the left saphenous nerve was used as an autograft. It was coapted to the motor branch to the rectus femoris muscle. Biopsies from both ends of the graft were taken. Animals were separated into four investigation groups, which were reexamined 3, 6, 9 and 12 months after the grafting procedure. Biopsies for histological and morphometric examination were again taken from the proximal and the distal part of the grafts. Thus, the number of myelinated nerve fibers in the different specimens could be obtained by computer-assisted image analysis. At the proximal end of the original saphenous nerve, the number of fibers varied between 1032 and 3100 (mean 2145). Corresponding data obtained from the distal end ranged from 1044 to 3084 myelinated nerve fibers (mean 1724). Fiber numbers in the proximal and distal parts of the grafts before and after regeneration were correlated to each other. In the whole population of specimens (correlation coefficient +/-0) as well as in the experimental subgroups, the quantitative success of neurotization in the grafts did not depend to a high degree upon the fiber numbers in the original saphenous nerve. The correlation coefficient for the proximal part of the graft exceeded 0.5 to only three and twelve months after grafting, but did not reach a level of statistical significance. In the distal part of the graft, the coefficient for a linear correlation was always less than 0.45.

Animals↗
PubMed1993

[Local and systemic infections with bacteria of group EF-4 in dogs, cats and in a badger: bacteriologic and pathologico-anatomic results].

Bacteria of Group EF-4 were isolated in 7 dogs and in 5 cats from local purulent lesions in areas of natural openings of the head and from bite wounds, from lungs with focal necrotizing pneumonia in 2 additional cats and from internal organs in a badger with septicemia. The organisms grew mostly in pure culture. In conventional biochemical tests, 12 isolates were shown to belong to biovar EF-4a and 3 isolates to EF-4b. Classification as Group EF-4 was confirmed by assimilation tests performed with the commercially available gallery ATB 32 GN. Results of this study indicate that in veterinary medicine, bacteria of Group EF-4 are not only important from an epidemiological point of view, but that they may be more pathogenic for animals than considered hitherto.

Animals↗