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Biomedical subjects

M Colombo

Publications and source records attributed to M Colombo.

At least 91 records · Page 5Linked to original sources
PubMed1993

The effects of inferior temporal and dorsolateral frontal lesions on serial-order behavior and visual imagery in monkeys.

Four monkeys were trained preoperatively on a serial-order task to respond to a set of five visual stimuli in a fixed sequence independent of their location. They were then given a test of visual imagery in which only two of the five stimuli appeared at a time, and the animals were required to respond to them in the order in which they appeared in the original sequence. The monkeys then received bilateral lesions of either inferior temporal cortex or dorsolateral frontal cortex. Dorsolateral frontal lesions had no effect on either serial-order behavior or visual imagery. In contrast, inferior temporal lesions severely impaired serial-order behavior. Once the serial-order task was relearned, however, the inferior temporal animals were completely normal on the test of visual imagery.

Animals↗
PubMed1993

Multicentre randomised controlled trial of recombinant interferon alfa-2b in patients with acute non-A, non-B/type C hepatitis after transfusion.

To assess whether the risk of chronic disease in patients with acute non-A, non-B/type C (NANB/C) hepatitis after transfusion could be reduced by treatment with interferon, patients were randomised to receive 3 million units interferon (IFN) alfa-2b three times a week for three months or no therapy. At the end of treatment, IFN had significantly reduced the number of patients with abnormal alanine aminotransferase activities compared with untreated patients but this difference was not maintained during a 15 month follow up. Treatment with IFN alfa-2b was considered safe and was well tolerated.

Acute Disease↗
PubMed1993

[Early severe malnutrition and psychomotor development. Effects of a rehabilitation program].

This study evaluates the psychomotor development of 228 undernourished infants submitted to an integral rehabilitation program in Nutritional Recovery Centers. At admission these children present a moderate retardation of their developmental quotient: mean 0.59 +/- 0.17, improving significantly to mean 0.79 +/- 0.4 (p < 0.001) after an average period of 178.2 +/- 63.9 days of intervention. As regards areas of development, rehabilitation only demonstrates a significant change in coordination and language, not so in the social and motor areas. Those children presenting the most severe developmental delays are also those who obtain the greater benefits from this integral rehabilitation program.

Developmental Disabilities↗
PubMed1993

Pharmacological characterization of FCE 27262, a combined thromboxane synthase inhibitor and PGH2/TXA2 receptor antagonist.

The literature supports the hypothesis that the association of a thromboxane (TX)A2 synthase inhibitor and a PGH2/TXA2 receptor antagonist has a superior antithrombotic effect when compared to both aspirin and single agent alone; a compound endowed with the dual mechanism of action might therefore be of therapeutic value for the management of thrombotic disorders. FCE 27262, an imidazol-1-yl-ethylideneaminooxypentanoic acid, displaces in vitro the binding of [3H]SQ 29,548 to washed human platelets (IC50 = 6.0 +/- 0.6 x 10(-8) M) and antagonizes human platelet aggregation induced by U 46619 in PRP with an IC50 (95% confidence limits) of 4.5(3.3-5.1) x 10(-7) M. It also selectively antagonizes the isolated vessel contraction induced by U 46619. In the rat aorta the Kb (95% confidence limits) was 1.6(0.6-4.3) x 10(-7) M. Additionally it inhibits in vitro TXB2 production in rat and human whole blood, the IC50 being, respectively, 5.9(3.3-9.6) x 10(-8) M and 3.8(2.9-5.0) x 10(-8) M. When administered orally to fed rats it also inhibits ex vivo TXB2 production in whole blood during clotting, the ID50 being 0.62(0.4-0.8) mg/kg. Both in vitro and ex vivo the effect of FCE 27262 on TXA2 synthase was selective, the production of PGE2, the product of a different isomerase from the common precursors, PG-endoperoxides, being concomitantly enhanced. In a canine model of electrically-induced coronary thrombosis, FCE 27262 (1 mg/kg i.v.) inhibits ex vivo TXB2 synthesis (> 95%), antagonizes U 46619-induced platelet aggregation and prolongs occlusion time (controls: 72 +/- 8 min, FCE 27262: 215 +/- 38 min; p < 0.01). In the same model both aspirin (5 mg/kg i.v.) and a pure PGH2/TXA2 receptor antagonist (L 670596), at a dose giving a similar degree of TXA2 synthase inhibition and receptor blockade, respectively, are significantly less effective. Thus, FCE 27262 combines thromboxane synthase inhibition and PGH2/TXA2 receptor antagonism in one molecule, resulting in enhanced antithrombotic activity. FCE 27262 thus may be an appropriate pharmacological tool to test the therapeutic potential of the dual mechanism of action.

Animals↗
PubMed1993

Direct characterization of caffeoyl esters with antihyaluronidase activity in crude extracts from Echinacea angustifolia roots by fast atom bombardment tandem mass spectrometry.

Fast atom bombardment (FAB-MS) and fast atom bombardment tandem mass spectrometry (FAB-MS/MS) techniques (negative ions) have been successfully applied for identification of the constituents responsible for the antihyaluronidase activity of Echinacea angustifolia roots, whose extracts are widely employed for the adjuvant therapy of chronic inflammatory diseases. Crude extracts from different solvents were tested for antihyaluronidase activity, and those with the greatest inhibitory action (the ethylacetate, butylacetate and chloroform fractions, IC50 0.44, 0.50 e 0.62 mg/ml) were directly analyzed by MS. Full scan mass spectra produced intense molecular anions: collisional activation of these resulted in tandem mass spectra rich in significant product ions. Four main caffeoyl conjugates were detected and identified by tandem mass spectrometry (daughter and parent ion mode): 2,3-O-dicaffeoyltartaric acid (chicoric acid) and 5-O-dicaffeoylquinic acid (cynarine) and 2-O-caffeoyltartaric acid (caffaric acid) in the ethylacetate fraction. Among these caffeoyl conjugates, chicoric and caftaric acids had the greatest antihyaluronidase activity: IC50 = 0.42 and 0.61 mM, while the IC50 of cynarine and chlorogenic acid were 1.85 and 2.25 mM.

Acetates↗
PubMed1993

Breakfast omission and cognitive performance of normal, wasted and stunted schoolchildren.

This study focuses on the effects of breakfast omission on cognitive performance. We studied 279 children from low socioeconomic level background ranging in age from 8 years 7 months to 10 years 11 months, categorized nutritionally as: normal, wasted or stunted. Evaluation comprised three cognitive tasks designed to be applied with a microcomputer. Assessment took place in their natural setting, after a mean of 14 h of overnight fasting, some having received a standard breakfast at random while the remaining children continued a fasting situation. We found no consistent association between study condition and performance in short-term visual memory, problem solving and attention tasks in any of the three nutritional groups. Stunted children showed significantly lower scores in the attention test irrespective of having received breakfast or not. These results suggest that given a motivating short-term task and maintaining routine conditions, missing breakfast does not affect the accuracy of the cognitive performance of children. Nutritionally affected children did not show a particular vulnerability to the fasting condition, but did show a specific cognitive deficit.

Attention↗
PubMed1993

A multicentre randomized clinical trial of recombinant alpha-2a interferon therapy in patients with chronic hepatitis B.

Fifty six previously untreated patients who had been positive for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) for more than 1 year with detectable serum levels of hepatitis B virus DNA (HBV-DNA) and a liver biopsy performed in the 6 months before enrollment, were randomized to receive recombinant alpha-2a interferon at doses of 3MU intramuscolarly thrice weekly for 6 months or no treatment. Treated and untreated patients had similar clinical characteristics in terms of ALT elevation, HBV-DNA levels, and degree of liver damage. Twenty one had chronic persistent or lobular hepatitis; 28 had chronic active hepatitis and 7 had cirrhosis. The percentages of patients who lost HBeAg at month 6, 12 and 18 were 22%, 32% and 38% in the treated group, and 16%, 20% and 37% in the controls (differences = ns). At the same time intervals, HBV-DNA detected by dot spot hybridization, cleared off in 39%, 39% and 41% of treated patients as compared to 16%, 36% and 37% of controls (difference = p < 0.05 for HBV-DNA clearance at month 6). At the end of follow-up, 12 treated patients (41%, including 8 antiHBe seroconverters) and 10 untreated controls (42%, including 6 anti-HBe seroconverters) had normal aminotransferase levels. Conclusions show that in patients with chronic hepatitis B, clearance of HBV-DNA but not of HBeAg was hastened by a 6-month treatment with low doses of recombinant alpha-2a interferon.

Adolescent↗
PubMed1992

The low risk of hepatitis C virus transmission among sexual partners of hepatitis C-infected hemophilic males: an international, multicenter study.

To study the transmission rate of hepatitis C virus (HCV) in the female sexual partners of antibody-positive hemophilic males, 106 partners from three hemophilia centers located in Europe, America, and Australia were tested for HCV seropositivity using a first-generation enzyme-linked immunosorbent assay (ELISA-1) and, subsequently, a second-generation ELISA (ELISA-2) and a supplemental recombinant immunoblot assay. Additionally, the cohort was tested for the presence of antibody to the human immunodeficiency virus type-1 and hepatitis B virus markers. No female partner was HCV antibody-positive using the ELISA-1 test, whereas five were seropositive by the ELISA-2 test. Three of these five female partners were seropositive on the supplemental test, the remaining two having indeterminate results, for an overall prevalence of 2.7%. Thus, even with the use of sensitive testing, the prevalence of HCV infection remains low in this cohort, showing that the efficiency of heterosexual transmission of HCV is poor.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Hepatitis C virus and hepatocellular carcinoma.

Epidemiological, clinical and laboratory data point to a role of hepatitis C virus infection in hepatocellular carcinoma. The connection appears to be indirect and to be mediated by cirrhosis. Thus, geographical differences can be observed, based on the locally prevalent etiological factors for cirrhosis. In the end, prospective studies of hepatitis C virus infected persons will be needed to elucidate the role of this agent in liver cancer.

Animals↗
PubMed1992

Development of antibody to hepatitis C virus (HCV) in acute and chronic non-A, non-B post-transfusion hepatitis.

The antibody to hepatitis C virus (anti-HCV) was measured by an immunoassay in 507 serum samples from 94 patients with acute and chronic post-transfusion non-A, non-B hepatitis (NANB) and in 436 healthy blood donors. Anti-HCV was found in 70.8 of patients with acute hepatitis, in 78.2 with chronic hepatitis, and in 1.4 of healthy blood donors. In acute hepatitis, anti-HCV appeared in the serum from 4 to 34 weeks after transfusion and from 1 to 30 weeks after the onset of the overt disease. Three patients with resolving hepatitis (21%) and 2 who developed chronic hepatitis (10%) lost anti-HCV during a mean follow-up period of 28 months. Among the 36 patients with chronic hepatitis, 2 (6%) lost anti-HCV after 12 months and 8 years respectively. These data indicate that in recent years HCV has been the major etiologic agent of acute and chronic transfusion-associated hepatitis (TAH) in our geographical area. The late appearance of anti-HCV from the onset of clinical and biochemical signs of acute hepatitis in more than 70% of patients limits the diagnostic utility of this assay for an earlier serological diagnosis of acute NANB hepatitis. Additional studies are required to determine the diagnostic significance of this antibody in chronic NANB hepatitis.

Adult↗
PubMed1992

The epidemiology of hepatitis delta infection in Italy. Promoting Group.

The epidemiology of HDV infection in Italy was assessed in a retrospective study involving 1556 HBsAg chronic carriers on their first presentation at one of the 35 Liver Units in 1987. Total anti-HD was detected in 23.4% of HBsAg carriers and was significantly more frequent in southern than in northern Italy (26.6% vs. 19.1%, p less than 0.01). Age distribution showed that 73% of the anti-HD-positive subjects, but only 56% of the anti-HD-negative subjects, were under 40 years of age (p less than 0.01). Anti-HD prevalence increased with the severity of the liver disease from 3.8% in healthy carriers to 42.5% in cirrhosis. No geographical statistical difference was found among HBsAg healthy carriers or subjects with chronic persistent hepatitis (CPH), while among patients with chronic active hepatitis (CAH) or cirrhosis anti-HD prevalence was much higher in the south (p less than 0.01). The various potential risk factors were evaluated by multiple logistic regression analysis. HDV infection was independently related to young age, residence in the south, i.v. drug abuse, a large family and household contact with an anti-HD-positive carrier. No association was found with blood transfusion or male homosexuality. These findings confirm that HDV infection is endemic in Italy, particularly in some southern areas, where intrafamily contact probably at a young age may favour the spread of the infection.

Adolescent↗
PubMed1992

Monoclonal antibody Ki-67 in the study of the proliferative activity of bladder carcinoma.

We studied the proliferative activity of bladder carcinoma using monoclonal antibody Ki-67, which is able to stain a nuclear antigen exclusively present in cells in the cell cycle, that is with activated deoxyribonucleic acid (DNA). We used this immunohistochemical technique on neoplastic tissue removed by transurethral resection from 101 patients. A significant correlation was observed (p less than 0.003) between cells with activated DNA and histological grading, even though within the context of each grade we observed tumors with a different proliferation index. Furthermore, we studied the location of the activated cells in the context of the tumor. In invasive tumors (stages T1 to T4) cells with activated DNA were always present at the base of implant of the tumor and in the neoplastic tissue that infiltrates the bladder wall. In regard to noninvasive tumors (stage Ta), in 57% of the cases most cells with activated DNA were present in the vegetative portion of the tumor and there were no recurrences at followup, while in 43% of the cases such cells were present also or especially at the base of implant of the tumor, near the lamina propria. In the latter patients we observed a 94% recurrence rate. These results suggest that the immunohistochemical assessment of the proliferative activity of transitional tumors of the bladder, using monoclonal antibody Ki-67, and the evaluation of the location of stained neoplastic cells provide a more reliable estimate of biological aggressiveness than that obtained with histopathological patterns alone.

Antibodies, Monoclonal↗
PubMed1992

Intellectual and physical outcome of children undernourished in early life is influenced by later environmental conditions.

Thirty-five schoolchildren who share a common history of early undernutrition and who were reared after recovery by adoptive families (16), in institutional care (eight) or by their biological families (11) were assessed for physical and intellectual outcome. The adopted children had mean normal weight and height for age, but the children from institutions were significantly shorter. Adopted children had mean Full-scale, Verbal and Performance IQs in the normal ranges, with significant differences from the other two groups, mainly for the Verbal subscale. These results emphasize that the growth and development of early-undernourished children are not irreversibly fixed by the acute illness, but are highly sensitive and modifiable by early and stable environmental improvement.

Adoption↗
PubMed1992

Binding capacities and affinities at mu-, delta- and kappa-opioid sites in membrane suspensions from guinea-pig brain regions.

Binding capacities and affinities (KD) of ligands at mu-, delta- and kappa-opioid binding sites were determined by selective labelling techniques together with analysis of saturation curves in seven regions of the guinea-pig brain. The kappa-sites predominated over the other sites in most regions and were 90% of the total in the cerebellum; binding capacities at kappa-sites were highest in the cortex, intermediate in the cerebellum, striatum and mesencephalon and lowest in the diencephalon, hippocampus and pons-medulla. At the mu-sites, binding capacities were highest in the diencephalon and mesencephalon, with intermediate levels in the pons-medulla, cortex and striatum, and low levels in the hippocampus and cerebellum. The highest binding capacity at the delta-sites was in the striatum, intermediate in the cortex, diencephalon and hippocampus, low in the mesencephalon and pons-medulla and not detectable in the cerebellum. No regional differences in binding affinities were found at mu-, delta- and kappa-sites with [3H]-[D-Ala2,MePhe4,Gly-ol5]enkephalin (KD = 1.10-2,61 nM), [3H]-[D-Ala2,D-Leu5]enkephalin (KD = 0.81-1.94 nM) and [3H]-(-)-bremazocine (KD = 0.083-0.185 nM). Thus in guinea-pig brain there are regional differences in opioid binding capacity and in the distribution of mu-, delta- and kappa-sites, but not in binding affinities.

Animals↗