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Biomedical subjects

B Colombo

Publications and source records attributed to B Colombo.

At least 19 recordsLinked to original sources
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↗
PubMed1987

Human beta-globin gene HpaI polymorphism in the non-white Cuban population.

The frequency of the association between the beta A, beta S and the beta C genes with the 13.0 kb HpaI restriction fragment has been determined in 72 non-white individuals with different hemoglobin phenotypes giving a value of 0.00 for the beta A gene, 0.52 for the beta S gene and 1.00 for the beta C gene. These data indicate that this association in the Cuban non-white population is similar to that reported for the American Blacks living in the U.S.A. East Coast and for the French West Indies.

Adolescent↗
PubMed1987

Erythrocyte PK deficiency: biochemical characterization of a patient with haemolytic anemia.

Erythrocyte pyruvate kinase deficiency was detected in a Cuban girl with congenital nonspherocytic haemolytic anemia. Kinetic and immunochemical studies showed that the case was different from those hitherto reported. The variant(s) was tentatively designated PK "Alquizar", following the recommendations of the International Committee for Standardization in Hematology.

Adenosine Diphosphate↗