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Biomedical subjects

B Colombo

Publications and source records attributed to B Colombo.

At least 73 records · Page 4Linked to original sources
PubMed1994

Bronchial responsiveness in patients on regular hemodialysis treatment of very long duration.

Several mechanisms (trapping of neutrophils, increased extravascular lung water, left ventricular hypertrophy, metastatic lung calcification, and iron deposition) may impair pulmonary function and alter bronchial responsiveness in patients on long-term regular dialysis treatment (RDT), but no studies have been published concerning patients on RDT for a very long time. To assess bronchial reactivity, a methacholine inhalation test was performed 2 to 24 hours after a dialysis session in 19 patients with RDT duration of almost 20 years (221 +/- 26 months) (group 1) and in 14 patients on RDT for a shorter time (24 +/- 22 months) (group 2); all patients had normal standard pulmonary function test results (group 1: forced vital capacity, 95% +/- 13% and forced expiratory volume in one second [FEV1]: 97% +/- 17%; group 2: forced vital capacity, 108% +/- 11% and FEV1, 108% +/- 9% of expected values). The methacholine provocation dose causing a 20% decrease in FEV1 was significantly lower than normal in seven (37%) group 1 patients and only in one (7%) group 2 patient; this difference was statistically significant (P = 0.049). There were no correlations between bronchial hyperresponsiveness and interdialysis weight gain, left ventricular hypertrophy, diastolic dysfunction expressed as the ratio between early diastolic filling and filling during atrial contraction, secondary hyperparathyroidism, and iron overload. Therefore, bronchial hyperresponsiveness is present in a substantial percentage of patients on RDT of very long duration, but the cause is unknown.

Adult↗
PubMed1994

Stimulation of Cl- secretion by the mucoactive drug S-carboxymethylcysteine-lysine salt in the isolated rabbit trachea.

Ion transport by the airway epithelium contributes to the regulation of the quantity and composition of respiratory tract fluid, thereby affecting mucociliary clearance. We have investigated the effect of the mucoactive drug S-carboxymethylcysteine-lysine salt (S-CMC-Lys) on the transepithelial bioelectric properties of isolated rabbit trachea. Transepithelial potential difference (Vms), short-circuit current (Isc) and resistance (R) were measured in the isolated rabbit trachea mounted between flux half-chambers, in the presence and in the absence of S-CMC-Lys (100 microM), added to the mucosal or submucosal chamber. In some experiments, tissues were also exposed to ion channel-inhibitors, in order to evaluate the contribution of Na+ and Cl- active transport to Isc. The excised rabbit trachea expressed transepithelial bioelectric properties based on an active ion transport supported by the Na(+)-K(+)-adenosine triphosphatase (ATPase) activity, since ouabain (500 microM) completely abolished the transepithelial potential difference. In control preparations, Vms and Isc declined significantly during 300 min recording, whereas R remained constant. The Isc decline was essentially attributable to a decrease in Cl- transport. Bumetanide (100 microM) almost completely abolished the Isc fraction related to Cl- transport. Treatment of the tissues with S-CMC-Lys reduced the progressive fall in Isc, with the most clear-cut and significant effect observed for the mucosal treatment. In parallel, S-CMC-Lys significantly lowered R, without affecting Vms. Either mucosal or submucosal exposure to S-CMC-Lys significantly increased Cl- secretion to normal values, whilst Na+ absorption was not modified.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Pulmonary involvement in scleroderma assessed with high-resolution computerized tomography and functional tests].

This study was aimed at investigating and analyzing lung involvement in scleroderma patients with different imaging methods, toward a rational diagnostic approach. Twenty-four patients with systemic sclerosis were examined with pulmonary function tests (PFT), spirometry and diffusing capacity for carbon monoxide (DLCO), chest radiography and high-resolution Computed Tomography (HRCT). Abnormal findings were present in 42% of cases on X-ray films and in 71% of cases on HRCT images. PFT was abnormal in the spirometries of 42% of cases and in DLCO tests in 50% of cases. The most common findings at HRCT were the small reticular and the ground-glass patterns. HRCT emerged as the most effective method to evaluate lung involvement in systemic sclerosis. In our series, HRCT allowed possibly curable lung lesions to be differentiated from incurable ones. However, HRCT is suggested in the patients with impaired pulmonary function to allow treatment choice; on the contrary, in the patients with no functional impairment, HRCT adds little information to clinical findings, showing only limited focal lesions.

Adult↗
PubMed1993

[Efficacy of and tolerance to a new NSAID in the treatment of arthrosis: droxicam. Randomized study versus tenoxicam].

A four-week open study was carried out to evaluate the efficacy and tolerability of droxicam, a new NSAID, in the treatment of painful osteoarthritis (OA). The results were compared with those obtained treating a similar group of patients with tenoxicam, at the same dosage of 20 mg/day, orally administered. The study showed that both drugs are effective in treating OA, with a mild predominance of droxicam in decreasing pain, functional limitation and chronic inability score. Tolerability was excellent or good in over 70% of patients and only one subject of each group was dropped out for severe side-effects. According to the Authors droxicam has shown to be an effective analgesic and anti-inflammatory agent as judged by its efficacy on pain relief and joint mobility in OA.

Adult↗
PubMed1991

Immunoglobulin heavy chain gene polymorphisms in Italian patients with psoriasis and psoriatic arthritis.

A polymorphism of the switch region of the mu IgH gene (S mu) is associated with arthritis in English patients with psoriasis. In this study, Italian patients with psoriasis alone (PS) or psoriatic arthritis (PSA) were analysed by Southern blot using DNA probes for the S mu region and a hypervariable locus 5' of the joining (JH) region of IgH (5' JH). No association between PSA and IgH gene polymorphisms was found. However, an association was found between PS and a genotype of the 5' JH region (Fisher's P = 0.0002, RR = 27). Additional DNA markers around the S mu region may reveal more accurate markers for PS or PSA.

Arthritis, Psoriatic↗
PubMed1991

Paraclinical tests in acute-onset optic neuritis: basal data and results of a short follow-up.

Up to now it is still doubtful whether there is a real risk of developing multiple sclerosis (MS) after initial monosymptomatic optic neuritis (ON). In this study we evaluated 43 patients with isolated acute-onset ON, in order to demonstrate the presence of oligoclonal bands (OBs) in the cerebrospinal fluid (CSF) and any additional clinically silent central nervous system (CNS) lesions. All examinations were performed from 5 days to 4 months (mean 43 days), from the onset of visual disturbances. Brain magnetic resonance imaging (MRI) detected white matter areas with increased signal in 21 patients (49%), while somatosensory and brainstem auditory evoked potentials revealed CNS abnormalities in only 5 patients (12%). OBs were present in the CSF of 20 patients (46%). Visual evoked potentials were abnormal in 39 patients (91%). Seven out of the 37 patients (19%) with at least one year follow-up, (mean duration of the follow-up = 32 months, range = 12-74), developed clinically definite MS (CDMS). All 7 patients had positive brain MRI and 6 had positive CSF examination at the basal evaluation. Our data suggest that MRI and CSF-OBs are the most reliable means of identifying patients with isolated ON who subsequently develop CDMS. They may therefore have a predictive value in defining MS risk.

Acute Disease↗
PubMed1991

Protection against malaria morbidity: near-fixation of the alpha-thalassemia gene in a Nepalese population.

We have previously reported that the Tharu people of the Terai region in southern Nepal have an incidence of malaria about sevenfold lower than that of synpatric non-Tharu people. In order to find out whether this marked resistance against malaria has a genetic basis, we have now determined in these populations the prevalence of candidate protective genes and have performed in-vitro cultures of Plasmodium falciparum in both Tharu and non-Tharu red cells. We have found significant but relatively low and variable frequencies of beta-thal, beta S, G6PD (-), and Duffy (a-b-) in different parts of the Terai region. The average in-vitro rate of invasion and of parasite multiplication did not differ significantly in red cells from Tharus versus those from non-Tharu controls. By contrast, the frequency of alpha-thalassemia is uniformly high in Tharus, with the majority of them having the homozygous alpha-/alpha-genotype and an overall alpha-thal gene (alpha-) frequency of .8. We suggest that holoendemic malaria has caused preferential survival of subjects with alpha-thal and that this genetic factor has enabled the Tharus as a population to survive for centuries in a malaria-holoendemic area. From our data we estimate that the alpha-thal homozygous state decreases morbidity from malaria by about 10-fold. This is an example of selection evolution toward fixation of an otherwise abnormal gene.

Animals↗
PubMed1990

A new beta-thalassemia mutation produced by a single nucleotide substitution in the conserved dinucleotide sequence of the IVS-I consensus acceptor site (AG----AA).

An Egyptian child with thalassemia major was found to carry two different haplotypes (I and VI) associated with two beta-thalassemic chromosomes. Analysis with several oligonucleotides and restriction enzymes, which identify the mutations most common in the Mediterranean area, allowed the identification of only one mutation, namely T----C at position 6 of the first intervening sequence (IVS-I). In order to characterize the other mutation the beta gene was amplified with polymerase chain reaction and sequenced. A G----A substitution was found at position 130 of the IVS-I which alters the conserved dinucleotide AG present in the consensus acceptor sequence, thus producing a beta (0)-thalassemia. This mutation was further confirmed by restriction analysis since it creates a new restriction site for the enzyme Afl II. It is concluded that this subject carries the IVS-I-6 mutation associated with haplotype VI, frequently observed in Mediterranean areas, and a new mutation at the acceptor site of the IVS-I, which has not been described before, associated with haplotype I. This thalassemic gene can be added to the list of mutations that can be identified by Southern analysis using Afl II.

Amino Acid Sequence↗
PubMed1990

Frequency of the -alpha 3.7 thalassemia deletion in the non-white Cuban population.

DNA analysis of the alpha-globin gene cluster showed that the frequency of the -alpha 3.7 deletion in the non-white cuban population is about 0.12, in agreement with a 47% admixture of the original African slaves introduced in the island. In the S-S homozygotes the frequency is slightly higher (.18), probably due to a selective advantage produced by the presence of alpha-thalassemia in sickle cell patients.

Anemia, Sickle Cell↗
PubMed1989

A case of hereditary persistence of fetal hemoglobin caused by a gene not linked to the beta-globin cluster.

The pattern of inheritance of several polymorphic restriction sites associated with the beta-gene cluster, and spanning a region of 52kb, demonstrates that a determinant for hereditary persistence of fetal hemoglobin (HPFH) segregates independently from the non-alpha globin gene cluster, as we postulated several years ago on purely genetical grounds. This finding provides additional evidence for the existence of diffusible factors affecting gamma-chain expression. Moreover, we have identified a "private" HincII polymorphism, in the vicinity of the epsilon gene in the family studied.

DNA Restriction Enzymes↗
PubMed1989

Polyamine biosynthetic decarboxylases in muscles of rats with different experimental myopathies.

The activities of the two polyamine biosynthetic decarboxylases (PBD), L-ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAMD), have been measured in quadriceps femoris of rats killed at different times after the induction of calciphylaxis- or serotonin(5-HT)-induced myopathy. Decreases in both PBD levels were observed at early times after both myotoxic treatments. Subsequent progressive increases in both enzyme levels were observed to nearly control values by 4 days after 5-HT administration. In the 5-HT-treated rats, the effects on the myocardial PBD activities were different from those in skeletal muscle, with no effect on ODC but much on SAMD, when rats were killed shortly after 5-HT injection. These results demonstrate that the time-course of the changes in PBD activities in quadriceps femoris mirrors quite well the successive occurrence of degenerative and regenerative processes during the calciphylaxis-induced myopathy and the 5-HT-induced myopathy; it is 5-HT that is mainly responsible for the decreases in PBD levels observed in both experimental myopathies, since dihydrotachysterol alone was without any effect on PBD activity levels and 5-HT alone was effective; myocardial ODC reacts more slowly to 5-HT than quadriceps femoris ODC.

Adenosylmethionine Decarboxylase↗
PubMed1989

Alpha-thalassemia changes the cell density profile in sickle cell anaemia.

Several factors are implied in the haematological and clinical picture of sickle cell anaemia. Attention has been focused on the concomitant presence of -alpha-thalassemia and high levels of HbF, but contradictory results have been reported in different populations. We compared the blood cell density profile, obtained by the phtalate esther method, of normal subjects with those of patients with sickle cell anaemia - with or without heterozygous alpha-thalassemia. We found that the density profile of both groups of patients differs from normal subjects, and that a difference can also be demonstrated between normal alpha genotype patients with sickle cell anaemia and patients with heterozygous alpha-thalassemia. These results are in agreement with the findings obtained in other countries in which a gene from Caucasian to African populations have been demonstrated, and are different from the results obtained in populations of more pure African ancestry. It can be suggested, therefore, that these data, in addition with findings of other authors in different geographical areas, support the hypothesis that the genetic make up plays an important role in the haematologic and clinical picture of sickle cell anaemia.

Anemia, Sickle Cell↗