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Biomedical subjects

J Sans

Publications and source records attributed to J Sans.

At least 19 recordsLinked to original sources
PubMed1999

Influence of copper-(II) on colloidal carbon-induced Kupffer cell-dependent oxygen uptake in rat liver: relation to hepatotoxicity.

Formation of reactive O2 species in biological systems can be accomplished by copper-(II) (Cu2+) catalysis, with the consequent cytotoxic response. We have evaluated the influence of Cu2+ on the respiratory activity of Kupffer cells in the perfused liver after colloidal carbon infusion. Studies were carried out in untreated rats and in animals pretreated with the Kupffer cell inactivator gadolinium chloride (GdCl3) or with the metallothionein (MT) inducing agent zinc sulphate, and results were correlated with changes in liver sinusoidal efflux of lactate dehydrogenase (LDH) as an index of hepatotoxicity. In the concentration range of 0.1-1 microM, Cu2+ did not modify carbon phagocytosis by Kupffer cells, whereas the carbon-induced liver O2 uptake showed a sigmoidal-type kinetics with a half-maximal concentration of 0.23 microM. Carbon-induced O2 uptake occurred concomitantly with an increased LDH efflux, effects that were significantly correlated and abolished by GdCl3 pretreatment or by MT induction. It is hypothesized that Cu2+ increases Kupffer cell-dependent O2 utilization by promotion of the free radical processes related to the respiratory burst of activated liver macrophages, which may contribute to the concomitant development of hepatocellular injury.

Animals↗
PubMed1998

[Pulmonary hypoplasia in adults: embryology, clinical presentation and diagnostic methods. Our experience and review of the literature].

We report five patients diagnosed of pulmonary hypoplasia (PH) in adulthood (age > 18 years, range 45 to 67 years). PH was left-sided in four cases. The malformations found were 2 cases of renal agenesis, 2 diaphragmatic hernias and 1 hiatal hernia. Lung function data were FEV1 0.88 +/- 0.32 L; FVC 1.30 +/- 0.52 L; FEV 1/FVC 68.5 +/- 5%. Arterial gases (with FiO2 0.21) were PaO2 63.6 +/- 24 and PaCO2 47.1 +/- 11.2 mmHg. Three cases were referred for monitoring of respiratory insufficiency (2 requiring home oxygen therapy) and two for radiographic study of chest disease. The diagnoses were made by computerized tomography (CT) of the chest. Congenital diseases due to underdeveloped lungs in the pseudoglandular phase are rarely diagnosed in adults (48 cases, including ours, have been found in the literature), and PH is rarely diagnosed, possibly because the anomalies observed are attributed to old infections. Clinical presentation is highly variable, depending in large measure on a history of smoking and repeated respiratory infections. Chest CT is at present the diagnostic tool of choice.

Aged↗
PubMed1997

Default cycle phases determined after modifying discrete DNA sequences in plant cells.

After bromosubstituting DNA sequences replicated in the first, second, or third part of the S phase, in Allium cepa L. meristematic cells, radiation at 313 nm wavelength under anoxia allowed ascription of different sequences to both the positive and negative regulation of some cycle phase transitions. The present report shows that the radiation forced cells in late G1 phase to advance into S, while those in G2 remained in G2 and cells in prophase returned to G2 when both sets of sequences involved in the positive and negative controls were bromosubstituted and later irradiated. In this way, not only G2 but also the S phase behaved as cycle phases where cells accumulated by default when signals of different sign functionally cancelled out. The treatment did not halt the rates of replication or transcription of plant bromosubstituted DNA. The irradiation under hypoxia apparently prevents the binding of regulatory proteins to Br-DNA.

Allium↗
PubMed1995

Impaired chromosome segregation in plant anaphase after moderate hypomethylation of DNA.

10(-6) M and 10(-5) M 5-azacytidine, demethylated around 9% and 17% of the 5-methylcytosine residues found in Allium cepa L. native DNA, respectively. Both treatments stimulated RNA synthesis in the cells of root meristems. On the other hand, the 10(-5) M treatment gave rise to multiple chromosomal anomalies in mitosis before any fall in the mitotic index was detectable, but no chromosomal breaks were ever seen. Serious lesions involved in chromatids and segregation in anaphase were preferentially found after hypomethylation of DNA sequences replicated in the second half of the previous S period: (i) sister telomeres remained unresolved at the cell equator while kinetochores had reached the poles, (ii) whole unsegregated chromosomes were pulled to one of the poles by obviously disfunctional kinetochores, resulting in an unbalanced distribution of chromatids, (iii) unsegregated chromosomes in other cells remained at the spindle equator as if kinetochores were nonfunctional, while cytoplasmic division took place before their migration to the poles. Frequently, a growing cytokinetic plate randomly cut the unsegregated chromosomes, giving rise to aneuploid nuclei. These anaphase failures are a firm basis to explain why the 10(-5) M treatment selectively depressed the rate of cell proliferation in these cells in the long run. On the other hand, if hypomethylation occurred at the first half of the previous S period, enlarged chromosomal segments were evident in most metaphases, while chromosome laggards and bridges were recorded in anaphase at rather similar frequencies after the different 5-azacytidine treatments. These data were consistently obtained both in the native mononucleate cells of meristems and in one subpopulation of synchronous cells labelled as binucleate by 5 mM caffeine.

Allium↗
PubMed1992

Early and late replicating DNA involved in the G1 to S transition in Allium cepa L meristematic cells.

The involvement of portions of the genome replicated at different times of the S period in the regulation of the G1 to S transition was analyzed in Allium cepa L meristem cells. For this, DNA bromosubstitution confined to discrete portions of a previous S period followed by anoxic UVA irradiation (300-400 nm light) was performed in synchronous cells. Sequences replicated in late S appeared to be involved in the positive regulation of the initiation of replication. Hence, cells were prevented from initiating replication if irradiated at mid G1 only when the DNA sequences replicated in the last third of the previous S period were bromosubstituted. Cycloheximide-induced inhibition of protein synthesis at late G1 also prevented the G1 to S transition. Sequences replicated in mid S appeared unrelated to any control of the initiation of replication. On the other hand, sequences replicated in the first third of the S period seemed to be involved in the negative regulation of the initiation of replication, since irradiation after previous bromosubstitution of early replicating DNA sequences advanced G1 cells into the next S phase and increased the proliferative fraction of the population. Finally, the simultaneous inactivation of DNA sequences involved in both positive and negative regulation of replication allowed the cells to enter into S.

Allium↗
PubMed1992

Impaired response to recombinant hepatitis B vaccine in HIV-infected persons.

We studied the immunogenicity of the standard schedule of recombinant hepatitis B vaccine (20 micrograms per dose at months 0, 1, and 6) in 21 anti-human immunodeficiency virus (HIV)-positive persons. Relatively low titers of anti-HBs developed in only five subjects (23.8%) 1 month after the third dose; all five had T4 cell counts greater than 700 cells/mm and none of the 11 subjects with a T4 cell count below this value responded. Five of the 16 nonresponders to the vaccine later had acquired immunodeficiency syndrome (AIDS)-related complex (two) and AIDS (three), while none of the responders did. Our results show that anti-HIV-positive persons are poor responders to the recombinant hepatitis B vaccine, and that the absence of a response is an indicator of a more severe immune deficiency and of a poor prognosis. An optimal regimen of hepatitis B vaccination in HIV-infected persons is still to be established.

Follow-Up Studies↗
PubMed1992

Effect of caffeine and isobutyl-methyl-xanthine on production of binucleate cells and on post-replicative repair.

Caffeine (CAF) but not 3-isobutyl 1-methyl-xanthine (IBMX) displayed a strong DNA anti-repair effect in G2 prophase, as estimated by the frequency of abnormal chromosomes in anaphase-telophase found shortly after treatment. IBMX is more effective than CAF in inhibiting cytokinesis, while the binucleate cells formed by a short treatment with any of these two xanthines have similar cycle kinetics.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Genome size variation and its phenotypic consequences in Phyllotis rodents.

Constitutive heterochromatin and genome size were studied in Phyllotis darwini, three Phyllotis xanthopygus subspecies, and their interspecific laboratory hybrids. P. darwini, with no or only small C-bands, had the smallest genome size; P. xanthopygus rupestris and P. x. vaccarum, with large C-bands in all the chromosomes, had the largest; and P. x. xanthopygus, with heterochromatin only in a few chromosomes, showed intermediate genome size. To examine some phenotypic consequences of nuclear DNA content, we measured nuclear and cellular surfaces and volumes. Linear regression analyses showed that all these cellular characters had a highly significant direct relationship with genome size. Hybrids had always the expected intermediate parental characteristics. Previous results indicate that P. x. vaccarum should have longer mitotic cycles and lower reproductive capacity than P. darwini. Our findings suggest that the "nucleotypic DNA" hypothesis, which considers genome size as an adaptive feature in higher plants and lower vertebrates, could be extended to these mammals. The analysis of heterochromatin and nuclear DNA amounts of other phyllotine and akodontine rodents supports the idea that small C-bands and genomes are ancestral conditions, from which independent and parallel events occurred until large genomes were produced.

Animals↗
PubMed1991

[Isochromosome 17q as the sole alteration in 2 patients with a myelodysplastic syndrome and its relation to myeloperoxidase activity].

Two patients diagnosed of myelodysplastic syndrome with an isochromosome i (17q) as the only chromosomal alteration are presented. The MAC method (i.e., morphology, antibodies, chromosomes) was applied in the study of one of the patients, it being found that all the myeloperoxidase-positive cells carried the i (17q) anomaly. Such finding might suggest that those patients with i (17q) as the only chromosomal alteration could have specific clinical and cytological features.

Aged↗
PubMed1989

The maintenance of colchicine-arrested metaphases in plants requires protein synthesis.

With the aim of finding out factors involved in chromosomal condensation, the kinetics of both metaphase accumulation and the subsequent formation of restitution nuclei in the presence of 1 mM colchicine have been analyzed in Allium cepa L. meristems. Restitution nuclei are formed by decondensation of the chromosomes from the c-mitoses and the reformation of nuclear envelopes around them. The study has been carried out in control conditions as well as in conditions which either inhibit protein synthesis (1 microgram/ml cycloheximide) or modify the accuracy of transcription (by near ultraviolet light irradiation under anoxia of cells with bromosubstituted-DNA). The results suggest that the high condensation of chromosomes observed in colchicine-arrested metaphases depends on sustained synthesis of protein, and that the DNA regions coding for such proteins are transcribed not before late prophase. By using cells, the genome of which has been partially bromosubstituted, fed bromodeoxyuridine during different fractions of this S period, it could be inferred that the coding regions for the proteins involved in chromosome condensation are probably multiple since they replicate throughout the whole S period.

Allium↗
PubMed1985

The transition point for protein synthesis in late S-G2 may be delayed by genome bromosubstitution without affecting the time of entry into mitosis.

Bromosubstitution for most of the S period in synchronous populations of Allium cepa L. meristematic cells resulted in a delay in the late S-G2 transition point where protein synthesis is needed for later mitotic entrance to occur. This retardation in the position of the transition point was not accompanied by the expected delay in the entrance into mitosis, suggesting that such protein synthesis is a requisite, but not a timer for prophase triggering.

Anisomycin↗
PubMed1981

[Circulating immune complexes-like material and complement in rheumatoid arthritis and ankylosing spondylitis (author's transl)].

Circulating immune complexes (IC) in 52 rheumatoid arthritis (RA) seropositive, 25 RA seronegative and 32 ankylosing spondylitis (AS) patients were assayed by two methods: 1) precipitation with a final 2% polyethylene glycol (PEG) concentration with immunoglobulins (Igs) quantitation in the precipitate and 2) the ability of IC to consume complement, evaluating conversion products from human C3 by bidimensional rocket immunoelectrophoresis. CH50, C3, C4, C3PA and circulating C3 conversion products were quantitated. IC precipitates with 2% PEG contained three classes of Igs: IgG, IgM and IgA, the latter being the most rare. In the control group Igs level precipitated with 2% PEG were: 2% PEG-IgG 2.5 mg/100 ml +/- 2; 2% PEG-IgM 0.72 mg/100 ml +/- 1.09; 2% PEG-IgA 0.04 mg/100 ml +/- 0.18. With 2% PEG IC-like material was detected in 58.5% of RA seropositive patients but none generated C3 conversion products. With neither methods was IC-like material detected in the RA seronegative group and none with 2% PEG in AS, either. However, in the latter, 21.8% generated C3 conversion products and 18.7% circulating C3 conversión products. In the RA seropositive patients no correlation was observed between the levels of 2% PEG-IgG and 2% PEG-IgM and the titre of antinuclear antibodies (ANA) nor between 2% PEG-IgG and that of IgG in serum. However, there was a low correlation between 2% PEG-IgM and that of IgM in serum and between 2% PEG-IgG and 2% PEG-IgM with rheumatoid factor (RF). It should be stressed that the value of the PEG method in the detection of IC-like material must be reconsidered, since using a 2% final concentration and a specific evaluation of Igs and complement components in the precipitate, it may be a method easy to perform and useful for clinical purposes.

Adult↗
PubMed1981

[Chest radiology in rheumatoid arthritis. A study of 89 patients (author's transl)].

Chronic interstitial pneumonia, necrobiotic nodules and pleural lesions are felt to be extraarticular manifestations of rheumatoid arthritis (RA). In a prospective study, posteroanterior and lateral chest X-ray films were taken in 89 patients with classical or definite RA (15 male and 74 female), of whom 64 (71.9%) were seropositive. The findings were compared with those of 103 age and sex matched controls. The chest X-rays were blindly evaluated by two of the authors (a pneumologist and a radiologist), and the presence of an interstitial pattern, nodules or pleural lesions was recorded. The following results were obtained: Interstitial pattern, in patients with RA, 5/89 (5.6%), and in controls, 5/103 (4.6%). Pulmonary nodules, in RA, 2/89 (2.2%), and in controls, 2/103 (1.9%). Pleural adhesions, in RA, 32/89 (35.9%), and in controls, 24/103 (23.5%). The results of the present series demonstrate that radiological pulmonary lesions are not more frequent in RA than in controls, similar conclusions having been reached by other authors.

Arthritis, Rheumatoid↗
PubMed1981

Protein synthesis during the onset of cell proliferation in root meristems.

Dormant meristems of Allium cepa L. root begin to sprout as soon as the water and temperature conditions are right. These cell systems offer many advantages when studying the earliest metabolic events related with the onset of the cell proliferating activity. By electrophoresis in SDS polyacrylamide gels the soluble protein fraction from meristems with increasing imbibition times was analysed. There are qualitative constancy and quantitative differences between electrophoretic patterns from dormancy to steady state conditions. It is suggested that polypeptide 8a, approximately 80,000 daltons in molecular weight, be considered an indicator of proliferative activity in the meristem.

Cell Division↗