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Biomedical subjects

M Rossi

Publications and source records attributed to M Rossi.

At least 433 records · Page 24Linked to original sources

[An open study on the clinical efficacy of citicoline in patients with chronic cerebral vasculopathy].

In this study we evaluated the safety/efficacy of citicoline in 30 patients affected by atherosclerotic processes with cerebral localization. Aim of this study was to confirm, from a clinical point of view, the efficacy of citicoline in increasing blood flow in the vascular zone and in exerting a trophic action on cerebral cells improving the symptoms related to the chronic cerebrovasculopathy. Therapeutic effect was evaluated, by means of subjective parameters, at the beginning, during and at the end of the study. The results obtained was statistically analyzed confirming the efficacy of citicoline on the subjective symptomatology. Safety was excellent in all cases.

Aged↗

Exo-glucosidase activity and substrate specificity of the beta-glycosidase isolated from the extreme thermophile Sulfolobus solfataricus.

The enzyme with beta-galactosidase activity from Sulfolobus solfataricus strain MT-4, like other enzymes of this type isolated from thermophilic sources, has broad specificity for beta-D-gluco-, fuco- and galacto-sides. The beta-galactosidase activity was purified by a new procedure that improved yields (44%) and final specific activity (182 units mg-1 at 75 degrees C using chromogenic beta-D-galactoside as substrate). The enzyme hydrolysed a large number of beta-linked glycoside dimers and oligomers; chromogenic beta-glucosides and beta-fucosides are the preferred substrates, and kinetic analysis indicated that they bind to a common catalytic site. The order of catalytic efficiency was beta 1-3 > beta 1-4 > beta 1-6 and cellotetraose > cellotriose > cellobiose for glucose dimers and oliogomers respectively. The cleavage occurred at the non-reducing end of the oligosaccharide, and the enzyme showed noticeable specificity also for the aglycone part of substrates. From these results the enzyme from S. solfataricus strain MT-4 is defined as a true glycosyl hydrolase with remarkable exo-glucosidase activity and it is designated S beta-gly.

Carbohydrate Sequence↗

[The use of totally implantable systems (TIS) for long-term endovenous therapy].

The availability of a long-term central venous access for the management of neoplastic and chronic patients is extremely important in order to achieve an easy and safe infusion of chemotherapeutic drugs, blood components, and parenteral nutrition. The authors evaluated 26 adult patients (25 with malignant tumors and 1 with severe asthma) in whom implantable catheter systems were placed subcutaneously between February 1989 and March 1992. Catheters were inserted through the cephalic vein in 13 cases, the subclavia vein in 8 cases and jugular vein in 5 cases. The mean function time was 262 days in deceased patients and 155 in alive ones. There were no infective or thromboembolic complications. The authors, in agreement with the literature, confirm that TIS represent a safe and easy access for a long term i.v. therapy, with a very low complication rate. Furthermore, comfort of the patients is substantially improved and nursing care is greatly facilitated.

Adult↗

Thermostable NAD(+)-dependent alcohol dehydrogenase from Sulfolobus solfataricus: gene and protein sequence determination and relationship to other alcohol dehydrogenases.

The NAD(+)-dependent alcohol dehydrogenase (EC 1.1.1.1) from the thermoacidophilic archaebacterium Sulfolobus solfataricus, DSM1617 strain (SSADH), has been purified and characterized. Its gene has been isolated by screening two S. Solfataricus genomic libraries using oligonucleotide probes. The encoding sequence consists of 1041 base pairs, and it shows a high preference for codons ending in T or A. The primary structure, determined by peptide and gene analysis, consists of 347 amino acid residues, yielding a molecular weight of 37,588. A level of identity of 24-25% was found with the amino acid sequences of horse liver, yeast, and Thermoanaerobium brockii alcohol dehydrogenases. The coenzyme-binding and catalytic and structural zinc-binding residues typical of eukaryotic alcohol dehydrogenases were found in SSADH with the difference that one out of the four structural zinc-binding Cys residues is substituted by Glu. The protein contains four zinc atoms per dimer, two of which are removed by chelating agents with a concomitant loss of structural stability.

Alcohol Dehydrogenase↗

In vitro biosynthesis of lactase in preweaning and adult rabbit.

Lactase is synthesized as a high-mannose large precursor (200 kDa) which is subsequently complex-glycosylated (215 kDa) and split into the 150 kDa mature form. The regulatory mechanisms responsible for the decline of activity at weaning are not yet known. We have set up in vitro cultures of intestinal mucosa from suckling and adult rabbit and found that suckling and adult animals synthesize the same four forms of lactase-phlorizin hydrolase (LPH) but with a different distribution. In the proximal adult small intestine there is very little 180 kDa form, which is most probably a product of the 215 kDa complex-glycosylated precursor. The 180 kDa form comprises a greater percentage of total LPH in the middle of the small intestine in adult and particularly in suckling rabbits. In the latter tissue this form is apparently more stable than in the adult tissue. Posttranscriptional control of lactase synthesis is therefore different in the various parts of the adult small intestine, and it is different in the suckling as compared to adult tissue.

Age Factors↗

Effect of beta-adrenoceptor blockade on dipyridamole-induced myocardial asynergies in coronary artery disease.

Twenty-one patients with angiographic evidence of significant coronary artery disease, and positive dipyridamole echocardiographic test results at basal condition and after 7 days of placebo treatment were prospectively studied to see whether beta blockade modifies the effects of dipyridamole echocardiographic testing on regional myocardial contractility. Patients were randomized to propranolol (120 mg/day) or placebo treatment in 3 divided doses for 7 days, after which each patient crossed over to the alternate regimen. Dipyridamole-echocardiographic testing was repeated at the end of each treatment. Propranolol abolished new mechanical signs of transient dipyridamole-induced ischemia (new wall motion abnormalities or an increase in degree of basal asynergies, or both) in 13 of 21 patients. The remaining 8 patients had positive results on dipyridamole echocardiographic testing after the propranolol treatment period. At basal conditions both heart rate and rate-pressure product were significantly reduced with propranolol; there was also a significant decrease in these parameters at peak dipyridamole infusion. At peak dipyridamole infusion heart rate and rate-pressure product were significantly lower in patients with negative than in those with positive echocardiographic test results after propranolol. Our data show that administration of beta blockade significantly reduces the development of transient dipyridamole-induced myocardial asynergies, the earliest markers of acute myocardial ischemia, detected with 2-dimensional echocardiography.

Adrenergic beta-Antagonists↗

[Phyllodes tumor of the breast].

The diagnosis of benign, malignant or borderline phylloides tumor of the breast is based on a combination of clinical and histological features but the biological behavior of this neoplasm is not often predictable: the most important indicators of malignant behavior are underscored. Only a few patients with malignant or borderline lesions develop distant metastasis; local recurrences do not appear to effect survival: as a consequence, wide resection should to be primary treatment and axillary dissection is not worthwhile.

Aged↗

A DNA polymerase from the archaeon Sulfolobus solfataricus shows sequence similarity to family B DNA polymerases.

The gene encoding the thermostable DNA polymerase from the archaeon Sulfolobus solfataricus (strain MT 4) was isolated by means of two degenerate oligonucleotide probes. They were designed on the basis of partial enzyme amino acid sequences. The gene was found to encode a 882 residues polypeptide chain with a deduced molecular mass of about 100 kDa. By comparison with other archaeal genes, putative regulatory sites were identified in the gene-flanking regions. By computer-assisted homology search, several sequence similarities among S. solfataricus and family B DNA polymerases were found. In addition, conserved sequence motifs, implicated in the 3'-5' exonuclease activity of E. coli DNA polymerase I and shared by various family A and B DNA polymerases, were also identified. This result suggests that the proofreading domains of all these enzymes are evolutionarily related.

Amino Acid Sequence↗

[A case of retroperitoneal leiomyosarcoma].

Leiomyosarcoma is a rare malignant tumour originating from the smooth muscular tissue in any part of the organism, including retroperitoneum where it is particularly aggressive. It is nearly always characterized by a silent development causing diagnostic delay. The results of the primary therapy, which is always surgical, are limited because of the tumoral mass extension and the high local aggressiveness. The Authors present a clinical case which was under their observation and seize the opportunity of making a revision of the literature about it.

Aged↗

Age-related loss of axospinous synapses formed by two afferent systems in the rat dentate gyrus as revealed by the unbiased stereological dissector technique.

Previous attempts to elucidate whether a loss of hippocampal synapses occurs during aging provided conflicting results, possibly due to the unavailability, at the time, of unbiased methods for synapse quantitation. This study was designed to reexamine the issue by means of modern technical procedures that provide unbiased estimates of synaptic numbers. Groups of 14 young adult (5 months old) and 14 aged (28 months old) male Fischer-344 rats were compared. Synapses were examined in the middle (MML) and inner (IML) molecular layer of the hippocampal dentate gyrus, where synaptic contacts are predominantly formed by different systems of afferents, the entorhinal and commissural-associational fibers, respectively. The number of synapses per neuron was estimated with the aid of the stereological dissector technique. The results showed that the total number of synaptic contacts per neuron was significantly diminished in the MML (by 23.6%) and IML (by 22.7%) of aged rats relative to young adults. This age-related synaptic loss involved axospinous, but not axodendritic, junctions of the MML (-24.4%) and IML (-24.0%). Both perforated and nonperforated axospinous synapses (distinguished by a discontinuous or continuous postsynaptic density, respectively) exhibited an age-dependent decrease in numbers, though this decrease did not reach statistical significance in the case of perforated junctions of the IML. The observed age-related loss of axospinous synapses may underlie the reduction in the amplitude of excitatory postsynaptic potentials and the decline in functional synaptic plasticity detected in the dentate gyrus of senescent rats.

Afferent Pathways↗

Structural synaptic plasticity associated with the induction of long-term potentiation is preserved in the dentate gyrus of aged rats.

Changes in synaptic numbers were examined in the hippocampal dentate gyrus of aged (28 months old) rats following the induction of long-term potentiation (LTP) by high-frequency stimulation of the medial perforant path carried out on each of 4 consecutive days. Potentiated animals were sacrificed 1 hour after the fourth stimulation. Stimulated but not potentiated and implanted but not stimulated rats of the same chronological age served as controls. Synapses were analyzed in the middle (MML) and inner (IML) molecular layer of the dentate gyrus. Using the stereological dissector technique, unbiased estimates of the number per neuron were obtained for the following morphological varieties of synapses: axodendritic synaptic junctions involving dendritic shafts, nonperforated axospinous synapses having a continuous postsynaptic density (PSD), and perforated ones distinguished by a fenestrated, horseshoe-shaped, or segmented PSD. The induction of LTP resulted in a selective increase in the number of synapses with segmented PSDs. This change was detected only in the potentiated synaptic field (MML), but not in an immediately adjacent one (IML), which was not directly stimulated during the induction of LTP. Comparison of these data with the results of our previous LTP study in young adult rats (Geinisman, Y. et al., 1991, Brain Res. 566:77-88) showed that the only significant difference in the absolute number of synaptic contacts per neuron between potentiated animals of the two chronological ages was an age-related reduction in segmented synapses of the MML. Relative increases in the number of segmented synapses per neuron were, however, virtually of the same magnitude in potentiated rats of both ages as compared with their respective controls. This finding may explain why senescent rats can be potentiated to the same extent as young ones.

Acoustic Stimulation↗

Activation of the Rhizobium leguminosarum glnII gene by NtrC is dependent on upstream DNA sequences.

The cloning and sequence determination is reported of the DNA region of Rhizobium leguminosarum coding for glutamine synthetase II (GSII). An open reading frame (ORF) encoding 326 amino acids was defined as the glnII gene on the basis of its similarity to other glnII genes and the ability of a DNA fragment carrying this ORF to complement the glutamine auxotrophy of a Klebsiella pneumoniae glnA mutant. We find that the glnII gene in R. leguminosarum is transcribed as a monocistronic unit from a single promoter, which shows structural features characteristic of rpoN (ntrA)-dependent promoters. In K. pneumoniae, such promoters require the ntrC and rpoN (ntrA) gene products for transcription. The intracellular level of glnII mRNA changes when R. leguminosarum is grown on different nitrogen sources, as expected for regulation by the nitrogen regulatory system. Promoter deletion analysis has shown that an extensive upstream DNA sequence (316 bp) is essential for in vivo activation of the glnII promoter in different biovars of R. leguminosarum. This DNA region requires a wild-type ntrC gene for activity and includes two conserved putative NtrC-binding site sequences. The results conclusively show that transcription from the R. leguminosarum glnII promoter is fully dependent on positive control by NtrC protein and on an upstream activator sequence (UAS).

Amino Acid Sequence↗

Patchy expression of lactase protein in adult rabbit and rat intestine.

Enzymatic and immunohistological analyses of lactase were performed at different stages of development and within different regions of the small intestine of the rabbit and rat. As previously reported, there seems to be a sharp decline of lactase activity on weaning but variable and higher levels of activity are seen in adult animals. Two monoclonal antibodies to rat lactase were available to study the protein in rats. Four monoclonal antibodies to human lactase were shown to cross-react with rabbit lactase and used for the rabbit studies. Immunohistological analysis of small intestine of adult rabbits and rats showed residual lactase protein within the enterocytes throughout the small intestine. In the middle of the small intestine (lower jejunum, upper ileum), uniform staining of the brush border was observed. In the proximal and distal regions, a patchy pattern of staining was observed. This pattern, which resembles that observed in adult hypolactasic humans, indicates an underlying heterogeneity of enterocyte differentiation.

Age Factors↗

Characterisation of the distribution of choline acetyltransferase messenger RNA in human spinal cord and its depletion in motor neurone disease.

We have characterised the distribution of choline acetyltransferase (ChAT) mRNA in spinal cord from normal and motor neurone disease/amyotrophic lateral sclerosis (MND) subjects by in situ hybridisation. High concentrations of ChAT-mRNA were detected in 4 main regions of spinal cord, layer IX of the ventral horn, layer III of the dorsal horn, the intermediate grey matter and layer X around the central canal. ChAT mRNA was most highly concentrated in layers IX and III. Substantial decreases in ChAT mRNA were detected in ventral grey matter (layer IX) of cervical and lumbar cord in all cases of MND. Smaller and more variable changes in ChAT mRNA were seen in MND in other regions of spinal cord which indicates that these changes may arise as secondary processes. The value of this technique in understanding the pathophysiology of MND is discussed.

Aged↗