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Biomedical subjects

S Silva

Publications and source records attributed to S Silva.

At least 19 recordsLinked to original sources
PubMed1995

Trace element reference values in tissues from inhabitants of the European Union. IX. Harmonization of statistical treatment: blood cadmium in Italian subjects.

Obtaining reliable trace element reference values in tissues and fluids from inhabitants of the European Union relies on the availability of standardized and harmonized protocols for the statistical treatment of the data on trace element levels in general European populations. In this context, cadmium was measured in the blood (BCd) of 514 Italian inhabitants from the Lombardy region and the results statistically treated and presented according to a procedure which includes: simple descriptive statistics and graphical analysis such as stem and leaf and box-plot representations (average BCd levels were 0.62 microgram/l; geometric mean, 0.51 microgram/l; median, 0.50 microgram/l; mode, 0.30 microgram/l; 95th percentile, 1.48 micrograms/l; 5th percentile, 0.20 microgram/l); p-p plot, Shapiro-Wilk and Lilliefors tests for normality (the distribution of the data is closer to the log-normal distribution and inconsistent with the hypothesis of normality); analysis of variance (BCd increases from 20 to about 60 years and then decreases; it is influenced by smoking but not by body mass and alcohol consumption and it is higher in men than in women); and step wise multiple regression analysis (BCd is influenced by the number of cigarettes/day and the total dose of exposure, cigarettes/day multiplied by smoking years). Tentative reference intervals for BCd based on the log transformation of the data are 0.14-1.82 micrograms Cd/l (whole population); 0.16-1.94 micrograms Cd/l (male) and 0.13-1.66 micrograms Cd/l (female); 0.24-2.68 micrograms Cd/l (smokers); and 0.14-1.27 micrograms Cd/l (non-smokers).

Adult↗
PubMed1995

Evaluation of satiety sensations and food intake after different preloads.

The reproducibility of three questions, related to fullness, satiety and desire to eat, rated on an unmarked triangle was verified. In four sessions 12 volunteers ate pasta with tomato sauce (520 kcal) and were asked to rate the sensations felt. There was no difference in rating scores of the replications so the proposed questionnaire provides a stable measure of sensations related to satiety. Subsequently three satiety conditions were studied. Two foods, one rich in carbohydrate, pasta (baked macaroni) and the other in protein, polpette (meatballs), were used as loads at two calorie levels and as preload before an "ad libitum" meal. All the three questions proved useful in discriminating between the different satiety conditions. The food intake underlines the specificity of satiety: subjects, after eating a preload which previously had satiated them, ate other foods in different amounts depending on the kind of preload eaten. Food intake was significantly higher after the pasta preload, furthermore "fullness" and "satiety" ratings were significantly highest after the meatball preload, suggesting that in our experimental conditions, meatballs were more satiating than pasta. In conclusion, this study highlights the validity of using several quite different questions to study hunger and satiety, together with the actual food intake.

Adult↗
PubMed1995

Defective natural killer cell cytotoxic activity in feline immunodeficiency virus-infected cats.

Flow cytometry has been employed to study NK cell cytotoxic activity in cats infected with feline immunodeficiency virus. The results show that animals infected for 12 months or more have decreased levels of NK cell cytotoxic activity in their blood. The impairment could not be overcome by in vitro treatment of effector cells with interleukin 2. Additional results suggest that the NK cells of infected cats are defective, in that they are still able to bind to target cells but have a reduced ability to kill them.

Animals↗
PubMed1994

Juxtaposition of N-myc and Ig kappa through a reciprocal t(6;12) translocation in a mouse plasmacytoma.

Nearly all mouse plasmacytomas (MPCs) carry an Ig/myc translocation. Any one of the three Ig loci may participate, while the myc contribution has been limited to c-myc, excluding other members of the myc gene family. The same is true for the other two known Ig/myc translocation-carrying tumors, Burkitt's lymphoma and rat immunocytoma. It is believed that the Ig/myc juxtaposition plays a decisive, rate limiting role in the genesis of the three tumors, acting through the constitutive activation of myc that makes it refractory to normal regulation. Here we describe the molecular analysis of a unique t(6;12)(CI;B) translocation that we previously identified in an exceptional MPC that expressed N-myc but not c-myc. We now show that the translocation led to the juxtaposition of N-myc and Ig kappa. This is the first case of an Ig/myc-carrying tumor that involves N-myc rather than c-myc. These findings suggest that the translocation may already have occurred at the pro- or pre-B cell stage at which N-myc is open for transcription. According to this interpretation, constitutive activation of N-myc would suppress the expression of c-myc, but would not interfere with the differentiation of the pro-B cell into a fully mature plasma cell. Its tumorigenic influence would become manifest only at the time when the cell would normally be programmed to leave the cycling compartment, in connection with its terminal differentiation.

Animals↗
PubMed1994

Hypersomy of chromosome 15 with retrovirally rearranged c-myc, loss of germline c-myc and IgK/c-myc juxtaposition in a macrophage-monocytic tumour line.

From a lymphoid tumour induced by 7,12-dimethylbenz-[a]-anthracene (DMBA) + methyl-N-nitrose-N-urea (MNU) in an [AKR Rb(6.15) x CBAT6T6]F1 mouse, a macrophage- monocyte line (KT-10) was isolated. Following ethyl methanesulfonate (EMS) treatment, a bromodeoxyuridine (BUdR) resistant subline was selected. Serial propagation of this line in vitro in the presence of BUdR (28 months) with periodic cytogenetic and molecular examinations, has led to the definition of four successive stages. During stage I, the cells were trisomic for chromosome 15. They contained Rb(6.15) and Rb(del6.15) of AKR and T(14;15) of CBA origin. Southern blotting showed the presence of both germline (G) and rearranged (R) c-myc. At stage II, Rb(del6.15) has duplicated. Both Rb(6.15) and T(14;15) persisted together with G-myc and R-myc. In stage III, the CBA-derived T(14;15) was lost, in parallel with G-myc. At this stage, a Dic.In(6.15) was detected. One of its arms was cytogenetically identical with the long arm of In(6.15) in the variant IgK/myc translocations. This chromosome carried R-myc and IgK in juxtaposition, as indicated by comigration on pulsed field electrophoresis (PFGE). At stage IV, the R-myc carrying AKR-derived chromosome 15s were present in six copies. Possible relationships between the increasing R/G myc ratio and changed growth characteristics in vivo and in vitro are discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Changes in central opioid receptor binding in relation to inflammation and pain in patients with rheumatoid arthritis.

A group of four patients with RA were examined to test the hypothesis that there is a change in the endogenous opioid system in the brain during inflammatory pain. Regional cerebral opioid receptor binding was quantified using the opioid receptor antagonist [11C] diprenorphine and positron emission tomography (PET). In the four patients studied in and out of pain, significant increases in [11C]diprenorphine binding were seen in association with a reduction in pain. Increases were seen in most of the areas of the brain that were sampled apart from the occipital cortex. Significant region-specific increases over and above the more generalized changes were also seen in the frontal, cingulate and temporal cortices in addition to the straight gyrus. These findings are consistent with the hypothesis that there are substantial increases in occupancy by endogenous opioid peptides during inflammatory pain.

Arthritis, Rheumatoid↗
PubMed1994

[Expectant management of missed abortion].

A hundred cases of consecutive missed abortion under expectant management are analysed. The average age for these patients was 29.1, 81% were multiparous, and in 65% of the cases they were not using any contraceptives in the last year. The mean score for haematocrit has no variations. These cases were resolved in an average of 12.8 days. In 42% of the cases, the abortion is complete and with no need for instrumentation. In 43% of the cases, curettage is necessary but in only 7% dilatation is necessary. In 16% of the cases there are some types of complications but in only 1% it is serious, not by the expectant management. Concluding that the conservative management in missed abortion cases represents a good alternative focussing classic dilatation and curettage in selected patients in which you can obtain an adequate continuation and subsequent control.

Abortion, Missed↗
PubMed1994

[Clinical study of 113 cases of malignant melanoma].

Malignant Melanoma (MM) incidence rate is increasing faster than many other cancer at present time. Its epidemiological and clinical behavior varies within countries. We have studied 113 cases of cutaneous melanoma from 1982-1993, that represents until now the largest series of MM studied in Chile. Superficial Spreading Melanoma was the most common type of MM with 37.5% of total cases followed by Nodular Melanoma 31.2%. Acral Melanoma 22.1%, and Lentigo Malignant Melanoma with 7.8%. MM favored females with 60.2% (n = 68) and males constituted 39.8% (n = 45) of all cases. Median age at diagnosis was 54 years. Primary more frequent location for man was thorax (36.4%) and lower extremities for women (28.6%). Hemorrhage, ulceration and rapid growth of a previously pigmented lesion as the primary cause for first medical visit were associated with high level of invasion, generally over 2 mm. thick. Color change and pruritus were associated with lower level of invasion. Patients in stage I (78.3%) had 1.35 mm of median invasive thickness in the primary lesion and patients in stage II (15.7%) had 3.03 mm.

Adult↗
PubMed1993

Nucleotide sequence and in vitro expression of the capsid protein gene of tobacco ringspot virus.

The nucleotide sequence of the 3' terminal 2022 nucleotides (nt) of tobacco ringspot virus (TobRV) RNA 2 has been determined. Protein microsequence analysis of the amino-terminal residues of purified capsid protein localized the capsid protein gene between nt 2014 and 583 (from the 3' terminus) of this sequence. The proteolytic cleavage site that is processed to liberate the capsid protein from the RNA 2-encoded polyprotein was identified as Cys-Ala. The predicted translation product from the gene is a 477 amino acid long polypeptide with a calculated MW of 53 kDa. The gene was modified at the 5' end to facilitate sub-cloning, and to provide it with a methionine initiation codon. The modified gene was sub-cloned, transcribed in vitro and expressed in a rabbit reticulocyte lysate translation system, where it directed the synthesis of a 53 kDa polypeptide. Garnier-Osguthorpe-Robson analyses of the secondary structure of the capsid protein predicted the presence of three beta sheet domains, which suggests that this nepovirus capsid may be structurally analogous to those of the como- and picornaviruses. These and other results from computer analyses of the nucleic acid and amino acid sequences, and comparisons with the capsid proteins of nepoviruses and other related viruses are discussed.

Amino Acid Sequence↗
PubMed1993

Differences in protein expression of Haemophilus somnus grown under conditions of iron-restriction.

Outer membrane protein profiles were compared in 14 H. somnus strains isolated from brain and lung lesions as well as from the genital tract of asymptomatic carriers during in vitro growth under iron-restricted conditions. Ethylenediamine-di-O-hydroxyphenyl acetic acid (EDDA) was used to obtain iron-restricted conditions in media used for this study. The outer membrane protein profiles were studied by the discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoretic system (SDS-PAGE), and the proteins were stained with silver or transferred to nitrocellulose sheets and western blots conducted. Growth under iron-restricted conditions resulted in the induction of outer membrane proteins in most H. somnus strains examined. Studies also indicated differences among H. somnus strains in the number of induced proteins and their molecular weights but the results did not indicate a specific relationship between these strain-dependent differences and tissue trophism. Western blot analysis revealed a high degree of immunological relatedness among strains of H. somnus in their iron-regulated proteins. However, hyperimmune serum used in these assays failed to recognize certain iron-regulated proteins expressed by some H. somnus strains, a finding which may have important implications for the induction of protective immunity in cattle against this bovine pathogen.

Animals↗
PubMed1993

MHC class I expression on prelymphomatous and lymphomatous B-cells is not inhibited by an E mu-myc transgene.

Increased expression of oncogenes from the myc family has been associated with down-regulation of major histocompatibility complex (MHC) class I molecules. In certain models this has been suggested to contribute to tumour progression. Transgenic mice bearing the cellular myc oncogene coupled to the lymphoid-specific immunoglobulin heavy chain enhancer (E mu) develop clonal B lymphoid malignancies early in life. We have asked if expression of such a constitutively activated E mu-myc transgene in BALB/c mice affects MHC class I expression. H-2Kd and Dd expression on prelymphomatous and lymphomatous B-cells as well as newly established pre-B or B lymphoma cell lines derived from E mu-myc transgenic BALB/c mice were analysed. The results reveal no down-regulated or otherwise altered expression of H-2Kd or Dd on any of the cell populations examined. The results are discussed in relation to the myc associated down-regulation of MHC class I molecules observed in other experimental models.

Animals↗
PubMed1993

Inositol 1,4,5-trisphosphate mass changes from fertilization through first cleavage in Xenopus laevis.

After fertilization in Xenopus laevis, inositol 1,4,5-trisphosphate (IP3) mass increased from 53 to 261 fmol/cell and returned to near basal by 10 min after insemination. IP3 was also elevated over control egg levels during first mitosis and first cleavage. Because IP3 levels and the fertilization calcium wave decline at about the same time and because calcium ionophore or pricking the egg increased IP3, the fertilization calcium wave may be due to calcium-induced IP3 production. In addition, the onset of sperm motility was associated with an increase, whereas the acrosomal reaction was accompanied by a decrease in IP3 mass. Combining our published data with this report, the first chronology of the levels of IP3 from the induction of meiosis (maturation) through fertilization and cleavage in one cellular system is summarized. These data suggest an in vivo dose response for IP3 and calcium release. A small (17 fmol/cell) IP3 change during the induction of meiosis may not be associated with a calcium change. Larger IP3 changes at cleavage (40 fmol/cell) and mitosis (125 fmol/cell) are associated with localized small calcium increases, whereas the largest IP3 change (208 fmol/cell) is associated with the large calcium increase at fertilization.

Acrosome↗