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Biomedical subjects

M Colombo

Publications and source records attributed to M Colombo.

At least 217 records · Page 12Linked to original sources
PubMed1989

Immunogenicity of a yeast-recombinant hepatitis B vaccine in high-risk children.

Horizontal transmission of hepatitis B virus (HBV) from illicit drug users to their contacts, including young children, can be prevented by active immunization against HBV. Yeast-recombinant hepatitis B vaccines are now available for this purpose, but their potential efficacy in such high-risk contacts has not yet been evaluated. Therefore we gave 20 mcg of a recombinant yeast-derived hepatitis B vaccine to 38 children who were at high risk for HBV infection because they had been institutionalized in a community for drug users in which 8.7% of the occupants are carriers. After third dose of vaccine (at 0, 1, and 6 months), all children had anti-HBs responses with titers of 10 mIU/ml or more, with 81% showing responses greater than 1,000 mIU/ml. At 12 months, the percentage of anti-HBs-positive children was 100%, and the percentage of children with anti-HBs higher than 1,000 mIU/ml was 56%. None of the children developed HBV infection during follow-up. Hence the recombinant vaccine was immunogenic, with percentages of seroconversion and anti-HBs titers comparable with those attained in other categories of high-risk children with plasma-derived vaccines.

Adolescent↗
PubMed1989

Serial learning with wild card items by monkeys (Cebus apella): implications for knowledge of ordinal position.

We investigated monkeys' knowledge of the ordinal positions of stimuli that formed a 5-item serial list, ABCDE, by means of wild card items (W) that could substitute for items in the original series. In Experiment 1, training with wild cards was given on 3-, 4-, and 5-item series. In the last of these series, the wild card substitutions created five wild card sequences, WBCDE through ABCDW. During the final 10 sessions of training with each of two different wild cards (Items x and Y), the 3 subjects were able to successfully complete almost 60% of the wild card sequences. In Experiment 2, the two wild cards were presented on the same trial in 10 different double wild card sequences (e.g., AXCDY). The 2 monkey subjects correctly completed about 59% of the double wild card sequences during the final two training sessions. The performance levels achieved on single and on double wild card sequences, although well below that observed on the baseline sequence ABCDE (90% or better), support the view that the monkeys possessed some knowledge regarding the ordinal position of each baseline item. Consequently, an associative chain interpretation, which does not provide for knowledge of ordinal position, falls short as a complete account of the monkey's capacity for serial learning.

Animals↗
PubMed1989

On the limits of the matching concept in monkeys (Cebus apella).

Two cebus monkeys, with many years of experience matching a variety of static visual stimuli (forms and colors) within a standard matching-to-sample paradigm, were trained to press a left lever when a pair of displayed static stimuli were the same and to press a right lever when they were different. After learning the same/different task, the monkeys were tested for transfer to dynamic visual stimuli (flashing versus steady green disks), with which they had no previous experience. Both failed to transfer to the dynamic stimuli. A third monkey, also with massive past experience matching static visual stimuli, was tested for transfer to the dynamic stimuli within our standard matching paradigm, and it, too, failed. All 3 subjects were unable to reach a moderate acquisition criterion despite as many as 52 sessions of training with the dynamic stimuli. These results provide further evidence that, in monkeys, the matching (or identity) concept has a very limited reach; they consequently do not support the view held by some theorists that an abstract matching concept based on physical similarity is a general endowment of animals.

Animals↗
PubMed1989

Beta-blockers in the secondary prevention of gastrointestinal haemorrhage in well-compensated cirrhotics. A multicentre randomised controlled study.

To assess the efficacy of beta-blockers in the prevention of rebleeding in selected cirrhotics and to compare the tolerability, safety of, and patient compliance with, a selective and a non-selective beta-blocker, 94 patients were randomly assigned to propranolol (32), atenolol (32), or placebo (30). Randomisation was made at least 15 days after the bleeding episode. Propranolol was given orally in increasing doses until the resting pulse rate was reduced by approximately 25%. Atenolol was given at a fixed dose of 100 mg/day. Patients were followed up for a mean of 357 days. Rebleeding occurred in 14 patients in the placebo group, 10 in the atenolol group and 8 in the propranolol group. The incidence of rebleeding was significantly lower in patients receiving propranolol than in those on placebo (PR vs PL: p less than 0.01, log-rank test). Atenolol was less effective than propranolol (AT vs PL: p = 0.065, log-rank test) but bleeding-free survival was improved for patients on active drugs compared with those patients on placebo (PR vs PL: p = 0.01; AT vs PL: p = 0.05, log-rank test). Retrospective analysis revealed that, whatever the type of treatment, abstinence from alcohol was crucial in preventing rebleeding. It was concluded that beta-blocker treatment is effective in preventing rebleeding from oesophageal varices in carefully selected alcoholic cirrhotics who survive at least 2 weeks after acute variceal haemorrhage and who cease drinking.

Adrenergic beta-Antagonists↗
PubMed1989

Long-term immunogenicity of a plasma-derived hepatitis B vaccine in HIV seropositive and HIV seronegative hemophiliacs.

Short-term studies indicate that hepatitis B vaccines are safe and satisfactorily immunogenic in hemophiliacs. The duration of immunity in these immunocompromised patients, however, is not known. To determine this, we studied 78 hemophiliacs prospectively 2, 3, and 4 years after the initial vaccination with a plasma-derived vaccine given as three monthly injections followed by a fourth booster injection at month 14. The duration of immunity clearly depended on whether the patients were infected with the human immunodeficiency virus (HIV). In HIV seronegative hemophiliacs (n = 67), there was a progressive decline in titers of antibody to the hepatitis B surface antigen (anti-HBs), but antibody was still detectable 4 years later in all of them. From the curves of decline of antibody titers, it appears that there is no need to revaccinate patients for at least 5 to 6 years. The HIV seropositive hemophiliacs (n = 11) not only started from much lower anti-HBs titers, but 5 of 11 lost anti-HBs. None of the 45 patients treated with concentrates during the postvaccination period developed serologic signs of hepatitis B, even though 6 of them had come into contact with live or inactivated hepatitis B virus as shown by the occurrence of spontaneous anamnestic antibody responses. This vaccine and schedule of vaccination afford a prolonged duration of immunity in HIV seronegative hemophiliacs, but HIV seropositive hemophiliacs have a risk of losing immunity early.

Adolescent↗
PubMed1989

Isolated gastric mucosa: an early approach to the study of the mechanism of action of gastric antisecretory agents.

The results of five different experiments carried out on isolated gastric mucosa were evaluated. These were: 1) Effects of antisecretory agents on (H+) and (K+) in a histamine-stimulated (4 x 10(-5)M) preparation. 2) Effects on (H+) in a preparation stimulated by dibutyryl cyclic adenosine monophosphate (dbcAMP) (6 x 10(-4)M). 3) Reversal by antipyrine (3 x 10(-2)M) of the antacid effect of antisecretory agents in a histamine-stimulated (4 x 10(-5)M) preparation. 4) Effects on the antacid activity of antisecretory agents of a pretreatment with 2-mercaptoethanol (2-ME) (2 x 10(-2)M) in a histamine-stimulated (4 x 10(-5] preparation. 5) Reversal by intraluminal increase of (K+) (up to 144.3 mM) of the antacid effect of antisecretory agents in a histamine-stimulated (4 x 10(-5)M) preparation. The technique and its application to a series of known antisecretory agents--cimetidine, ranitidine, timoprazole and omeprazole--and to other substances with antisecretory activity such as sodium thiocyanate, verapamil, trimipramine and imipramine, is described. In order to illustrate the activity of the aforementioned substances in the more classic tests of antisecretory activity, an in vivo test of inhibition of gastric secretion in pylorus-ligated rats and the in vitro tests of H2-receptor blocking activity (isolated guinea-pig atrium), anticholinergic activity (isolated guinea-pig ileum) and carbonic anhydrase (canine blood) were included. The results show that substances with different mechanisms of action behave differently in the five experiments in isolated gastric mucosa described, and these may thus be considered useful for the study of the mechanism of action of gastric antisecretory agents.

Animals↗
PubMed1989

[Skin metastasis of clear cell carcinoma of the kidney].

A case of a 70 year old man, affected by a solitary cutaneous metastasis of a clinically asymptomatic clear cell adenocarcinoma of the kidney is reported and some histopathological differential diagnoses are considered.

Adenocarcinoma↗
PubMed1989

Maximum tolerated temperature in the rat tail: a broadly sensitive test of analgesic activity.

The methods most frequently employed for the study of analgesic activity of opiates are those based on thermal stimuli (hot-plate, tail-flick, TWR). These tests, however, are only sensitive for opiates which are pure agonists. In this work, we propose a modification of the TWR method capable of detecting analgesic activity in both agonist and agonist-antagonist opiates. In addition, non-opiate analgesics also show activity in this test. The ED50 (mg/kg, i.p.) of the substances studied, administered 30 min before commencement of the test, were as follows: buprenorphine: 0.02; methadone: 0.08; morphine: 1.9; pentazocine: 4.5; d-propoxyphene: 5.5; codeine: 7.6; pethidine: 9.2; zomepirac: 20.1; suprofen: 138.0; acetylsalicylic acid: 453.4. There was a statistically significant linear correlation between the results obtained by the proposed method (MTT) and those of some of the most frequently used methods for the study of analgesic agents (writhing induced by phenylbenzoquinone, acetic acid, acetylcholine bromide, hot-plate test and rat tail withdrawal test). The simplicity of the method makes it suitable for use in the battery of screening tests for analgesic activity of both narcotic and non-narcotic substances.

Acetates↗
PubMed1988

Intrahepatic chemotherapy for unresectable hepatocellular carcinoma.

From 1976 to 1983, 28 patients (24 male and four female) with unresectable hepatocellular carcinoma (HCC) were treated by intraarterial chemotherapy at the Istituto Nazionale Tumori of Milan, Milan, Italy. Tumors were retrospectively classified by a previously proposed staging system. Two patients were classified as Stage I and 26 as Stage II. Liver cirrhosis was present only in the males (in 50% of them). Nineteen patients were treated with doxorubicin (Adriamycin [Adria Laboratories, Columbus, OH]) and nine with 5-fluorouracil. Systemic toxicity was mild, but the treatment induced hepatic toxicity (ascites, clinical jaundice, or biochemical impairment) in 18% of noncirrhotic and 66% of cirrhotic patients. Clinical reduction of hepatomegaly was observed in 50% of noncirrhotic versus 16% of cirrhotic patients. Doxorubicin was effective in 66% of noncirrhotic patients and 20% of cirrhotic patients, with an overall response rate of 42%. 5-fluorouracil was effective only in patients without cirrhosis, with an overall response rate of 22%. Overall median actuarial survival was 3.5 months, with a significant difference between noncirrhotic and cirrhotic patients (6 versus 2 months, respectively). Overall median survival of patients who responded to the treatment was 13 versus 2 months for nonresponders (P less than 0.001). Liver cirrhosis was the most important prognostic factor in terms of liver toxicity, response rate, and survival. This study emphasized the negative impact of the treatment on cirrhotic patients. Also, the real value of intraarterial administration of doxorubicin was investigated.

Adult↗
PubMed1988

Immunogenicity of a recombinant hepatitis B vaccine in hemophiliacs.

Yeast-recombinant vaccines against hepatitis B virus (HBV) are now available, but there is no information about whether or not they are immunogenic in patients with hemophilia and other congenital bleeding disorders. Twenty micrograms of a recombinant vaccine expressing the adw serotype of the hepatitis B surface antigen (HBsAg) were given to 41 patients negative for HBV markers and again after 1 and 6 months. Ten percent of the vaccinees had anti-hepatitis B surface antibody (anti-HBs) responses, with titers of 10 mIU/ml or more, 1 month after the first dose of vaccine. The percentage of anti-HBs-positive patients increased to 54% after the second dose and to 98% after the third dose, with only one non-responder. Hence, the recombinant vaccine was immunogenic, with percentages of seroconversion and anti-HBs titers similar to those achieved with plasma-derived vaccines.

Adolescent↗
PubMed1988

Ultrasound-assisted percutaneous liver biopsy: superiority of the Tru-Cut over the Menghini needle for diagnosis of cirrhosis.

A total of 1192 consecutive patients with diffuse liver disease were randomized to have percutaneous liver biopsy specimens taken with the Menghini or the Tru-Cut needle, to compare tissue yield, safety, and accuracy of the two needles for diagnosing cirrhosis. The sites of puncture were determined by prebiopsy ultrasound scans. Adequate samples were obtained from 94% with the Tru-Cut needle and from 79.2% with the Menghini needle (p less than 0.001). Accuracy in diagnosing cirrhosis was 89.5% for the Tru-Cut needle and 65.5% for the Menghini needle (p less than 0.05). Complication rates were very low and similar for both needles. Under these conditions, the Tru-Cut needle is superior to the Menghini needle for diagnosing cirrhosis.

Biopsy, Needle↗
PubMed1988

Antagonism by N-methyl levallorphan-methane sulphonate (SR 58002 C) of morphine-elicited acute and chronic central and peripheral effects.

The peripheral activity of the quaternary narcotic antagonist N-methyl levallorphan-methane sulphonate (SR 58002 C) at opioid sites located in the periphery and in the central nervous system (CNS), was studied by different approaches in rats after subcutaneous injection (s.c.). Pretreatment with SR 58002 C 2,8 or 32 mg/kg s.c. 10, 50 or 110 min before buprenorphine consistently reduced buprenorphine in vivo binding only in the small intestinal longitudinal muscle with attached myenteric plexus (MP), whereas naloxone (1 mg/kg s.c.) 10 min before buprenorphine lowered buprenorphine binding in MP and brain (without cerebellum). Plasma levels were not altered by SR 58002 C or naloxone. The same doses of SR 58002 C injected 10, 50 or 110 min before morphine selectively antagonized the inhibition of transit of a charcoal meal along the small intestine (mainly a peripheral effect) induced by the agonist, but did not antagonize morphine-elicited analgesia in the hot-plate test (central effect). Naloxone (1 mg/kg s.c.) injected 10 min before morphine antagonized both agonist effects simultaneously. In morphine-dependent rats SR 58002 C (0.25, 1, 4 and 32 mg/kg s.c.) induced diarrhea, dose-dependently, in most animals within the first 30 min, while jumping, measured in the same rats, occurred in some animals, not dose-dependently, from 60 min on. Naloxone (1 mg/kg s.c.) induced both effects in most rats. These findings suggest that, although SR 58002 C probably penetrates the blood-brain barrier in some morphine-dependent rats, it discriminates peripheral and CNS opioid effects.

Animals↗
PubMed1988

Prospective study of hepatitis after factor VIII concentrate exposed to hot vapour.

A factor VIII concentrate prepared from large plasma pools and then exposed to hot vapour to inactivate blood-borne viruses was evaluated in 28 factor-VIII deficient patients (14 vaccinated against the hepatitis B virus, HBV) who had not been treated with any blood product and hence were highly susceptible to the development of post-transfusion hepatitis. Tests for aminotransferases and HBV markers were made every 2 weeks in the first 4 months and at 5, 6 and 12 months. Twenty-four patients were considered not to have developed hepatitis, either because they had no elevations of aminotransferases or did not become seropositive for HBV markers. The four remaining unvaccinated patients (three treated with the same batch and the fourth with a different one) developed HBV infection 8-24 weeks after the first concentrate infusion. Hence, this method of viral inactivation did not afford complete protection from hepatitis B.

Adolescent↗