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Biomedical subjects

A Gabriel

Publications and source records attributed to A Gabriel.

At least 19 recordsLinked to original sources
PubMed1992

Transplantation of fetal mouse colon under the kidney capsule of an adult mouse: a model for the study of colonic development.

Fourteen-day fetal mouse colon was transplanted under the kidney capsule of an adult mouse to determine whether this system could be used as a model of embryonic colonic development. The 14-day fetal colon was transplanted and left for a period of 7 days. Comparisons of the normal one day postnatal colon and the transplanted colon were made morphologically and morphometrically. It was found that the transplanted fetal colon resembled its postnatal counterpart with respect to morphology; the cell types seen in the transplanted colon were similar to those observed in the in situ colon of the same age. However, morphometric analysis showed that the transplanted colon was significantly smaller than its postnatal counterpart, suggesting that conditions in the host were not optimal to support the full growth of the colon. In spite of this, it appears that the fetal colon can differentiate normally under the kidney capsule and this model can be used to study both epithelial-mesenchymal interactions and the role of hormones in fetal colonic development.

Animals↗
PubMed1992

Non-invasive vs. invasive beat-to-beat monitoring of blood pressure.

The present study focuses on the accuracy in tracing fast beat-to-beat changes in blood pressure using a non-invasive technique. The measurements using a commercially available apparatus (Finapres, Ohmeda, USA) were compared to ipsilateral intra-arterial radial pressure. Eight patients were studied at rest, during deep breathing with a fixed rate of 6 breaths min-1, and during an exercise test on an ergometer cycle. A total of 900 systolic pressure values were included for statistical evaluation, covering a pressure range of 86-266 mmHg. On average the systolic correlation coefficient for the whole material was 0.97, with a range of 0.94-0.996. For mean pressure the correlation coefficient was on average 0.97, and for diastolic pressure 0.93. No systematic difference between the non-invasive and the invasive method was found, although for each individual patient a difference between direct and indirect measured blood pressure existed that could be relatively large (systolic pressure: average difference = 0.8 mmHg, SD = 16 mmHg). We found the method easy to handle and consider it excellently suited to track relative changes in blood pressure.

Aged↗
PubMed1992

[The role of antiglobulin antibodies in pathophysiology of various internal diseases].

Antiglobulins are a heterogenous group of antibodies specific for a large number of antigenic determinants on the heavy chains of various classes and on light chains. They are capable of reacting with hidden antigenic determinants of gamma globulins after they have been exposed by the action of proteolytic enzymes or after antigen-antibody reaction during which changes occur in the spatial configuration of the Fc fragments of immunoglobulin causing that they assume immunogenic properties. Antiglobulin antibodies against episomes in the Pab fragment of other antibodies have a strong regulatory influence on the immune response in view of their ability of specific interference with the response to a specific antigen. Antiglobulin antibodies may exert a protective effect but also a pathogenic effect. The latter has been demonstrated in atopic diseases, in IgA glomerulonephritis, in rheumatoid arthritis, in infectious mononucleosis, cryoglobulinaemia, in patients with IgA deficiency associated with presence of antiglobulin antibodies to IgA after transfusion of plasma or intravenous infusion of gamma globulins containing IgA.

Antibodies, Anti-Idiotypic↗
PubMed1991

Reverse transcriptase encoded by a human transposable element.

L1 elements are highly repeated mammalian DNA sequences whose structure suggests dispersal by retrotransposition. A consensus L1 element encodes a protein with sequence similarity to known reverse transcriptases. The second open reading frame from the human L1 element L1.2A was expressed as a fusion protein targeted to Ty1 virus-like particles in Saccharomyces cerevisiae and shown to have reverse transcriptase activity. This activity was eliminated by a missense mutation in the highly conserved amino acid motif Y/F-X-D-D. Thus, L1 represents a potential source of the reverse transcriptase activity necessary for dispersion of the many classes of mammalian retroelements.

Base Sequence↗
PubMed1991

Reverse transcriptase encoded by a retrotransposon from the trypanosomatid Crithidia fasciculata.

The long interspersed nuclear element (LINE)-like elements are a distinct family of eukaryotic transposons that contain a long open reading frame with limited sequence homology to retroviral reverse transcriptases. Unlike many retrotransposons, they lack long terminal repeats. The mechanism by which LINE-like elements move within the genomes of their hosts remains speculative. We have used an unusual approach to express and detect enzymatic activities associated with Crithidia retrotransposable element 1 (CRE1), a site-specific LINE-like element found in the insect trypanosomatid Crithidia fasciculata. A chimeric gene fusing the yeast retrotransposon Ty1 and the CRE1 open reading frame is constructed and then overexpressed in yeast. Fusion proteins are packaged into virus-like particles, which can be partially purified and directly analyzed for enzymatic activity. Here we demonstrate that CRE1 encodes an RNA-directed DNA polymerase. These data provide direct biochemical evidence that this widely distributed class of retrotransposons encodes reverse transcriptase and sets the stage for a detailed understanding of the mechanisms involved in LINE-like element transposition.

Animals↗
PubMed1990

The relationship between carcass characteristics, plasma hormones and metabolites in young fattening bulls.

Six Belgian Blue bulls (double-muscled type) and six Friesian bulls were offered a fattening diet for 34 weeks. Plasma samples were obtained once a week and also every 20 min over a 24 h period, 7 weeks before slaughter. No differences were observed between the breeds in plasma glucose, urea and free amino nitrogen concentrations, while creatinine was significantly higher in the Belgian Blue bulls. Tri-iodothyronin, tetra-iodothyronin, insulin-like growth factor 1, insulin and testosterone concentrations were higher in the Holstein group. In contrast, the Belgian Blue bulls appeared to produce more growth hormone. The slaughter weight, carcass weight, dressing percentage and proportion of lean meat were significantly higher in the Belgian Blue group. The characteristics of muscle mass (carcass weight, dressing percentage and proportion of lean meat) were positively correlated with creatinine and with the total peak area or peak amplitude of growth hormone. The insulin concentration was positively correlated with the proportion of adipose tissue in the carcass and negatively correlated with the proportion of muscle. There were no correlations between the carcass characteristics and insulin-like growth factor 1 or testosterone. No further information was provided when the ratios of the hormones were correlated with carcass characteristics.

Age Factors↗
PubMed1990

Effects of 5-azacytidine in Syrian golden hamsters: toxicity, tumorigenicity, and differential modulation of bronchial carcinogenesis.

5-Azacytidine (AZC) was studied in a lung cancer model in outbred and syngeneic (F1D) hamsters wherein benzol[a]pyrene (BP) from sustained release implants (SRI) induces preneoplastic mucosal changes which progress to bronchogenic cancer. In pilot studies to evaluate AZC toxicity, a dose schedule of 5 mg/kg biweekly was found suitable and was then used for long-term administration in all subsequent studies. Three groups of outbred hamsters were studied: BP SRi alone (n = 60), BP SRI + AZC (n = 60), and AZC alone (n = 54). AZC treatment was begun 3-5 days after SRI placement. Sixty-one days after the start of the experiment, seven or eight hamsters were sacrificed from each group. Later sacrifices were at 3-week intervals in groups receiving BP SRI and at 6-week intervals in the AZC only group. Four groups of F1D syngeneic hamsters were studied: BP SRI alone (n = 50); BP + AZC starting 3-5 days after SRI placement and continuing until death (n = 52); BP + AZC from 3 to 5 days until 75 days after SRI placement (n = 49); BP + AZC starting 80 days after SRI placement and continuing until death (n = 52). Hamsters (n = 9-14) from each group were sacrificed at 120, 150, 180, and 220 days after SRI implantation. AZC alone was not carcinogenic under these conditions. Both outbred and F1D hamsters treated with early or continuous AZC had slower rates of neoplastic change from BP SRI than did animals receiving BP SRIs alone or BP + late AZC. The incidence of epidermoid cancer were the same for all regimens, but the tumors in those receiving AZC early in carcinogenesis were smaller than in those receiving late or no AZC. The incidences of nonepidermoid cancer were lower in those receiving AZC during early carcinogenesis, and larger tumors were noted in the absence of AZC. Thus, within the study period in this unique hamster lung cancer model, AZC given early in carcinogenesis inhibited only the later (promotional) phase of BP epidermoid carcinogenesis, but inhibited all phases of nonsquamous cancer development induced by BP. This differential modulation of bronchial carcinogenesis, which occurs from AZC given during preneoplastic stages, may prove useful for delineating molecular mechanisms underlying specific phenotypic types of bronchogenic cancers.

Animals↗
PubMed1990

A rapidly rearranging retrotransposon within the miniexon gene locus of Crithidia fasciculata.

The tandemly arrayed miniexon genes of the trypanosomatid Crithidia fasciculata are interrupted at specific sites by multiple copies of an inserted element. The element, termed Crithidia retrotransposable element 1 (CRE1), is flanked by 29-base-pair target site duplications and contains a long 3'-terminal poly(dA) stretch. A single 1,140-codon reading frame is similar in sequence to the integrase and reverse transcriptase regions of retroviral pol polyproteins. Cloned lines derived from a stock of C. fasciculata have unique arrangements of CRE1s. In different cloned lines, CRE1s, in association with miniexon genes, are located on multiple chromosomes. By examining the arrangement of CRE1s in subclones, we estimate that the element rearranges at a rate of ca. 1% per generation. These results indicate that the C. fasciculata miniexon locus is the target for a novel retrotransposon.

Amino Acid Sequence↗
PubMed1990

Animal performance, plasma hormones and metabolites in Holstein and Belgian Blue growing-fattening bulls.

Six Holstein (light-muscled type) and six Belgian Blue bulls (double-muscled type) were fed a finishing diet. Average daily gain was 1.36 kg for the Holstein bulls vs 1.24 kg for the Belgian Blue bulls (P less than .05). Holstein bulls consumed more feed (2.3 vs 1.8 kg/100 kg body weight, P less than .001) than the Belgian Blue bulls. The dressing percentage (55.4 vs 65.8%, P less than .001) and the proportion of muscle (56.1 vs 71.3%, P less than .001) in the carcass were less, whereas the proportions of adipose tissue (28.3 vs 15.4%, P less than .001) and bone (15.7 vs 13.4%, P less than .05) were higher in the Holstein bulls. Plasma creatinine determined in samples obtained once a week was lower (11.0 vs 20.3 mg/liter, P less than .001) in the Holstein bulls. In contrast, Holstein bulls tended to produce more triiodothyronine (2.3 vs 1.8 nM, P less than .10), tetraiodothyronine (71.9 vs 54.7 nM, P less than .10) and insulin-like growth factor I (IGF-I; 340 vs 205 ng/ml, P less than .20) than the Belgian Blue bulls. Growth hormone, insulin, IGF-I and testosterone were measured at 20-min intervals during two 24-h periods. In wk 6, Holstein bulls tended to produce more growth hormone than the Belgian Blues, as indicated by higher total peak area (3,185 vs 2,431 ng), peak amplitude (34.1 vs 22.6 ng/ml, P less than .10) and baseline (4.6 vs 3.3 ng/ml, P less than .20). In wk 27, the trends were opposite.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1990

Quantitative DNA alterations during 5-azacytidine-induced differential modulation of benzo(a)pyrene carcinogenesis in hamster bronchi.

Sustained release implants (SRI) containing 10% benzo(a)pyrene (BP) were placed endobronchially into outbred and syngeneic (F1D) hamsters. Randomly selected OB and F1D hamsters also received 5-azacytidine (AZC), 5 mg/kg i.p., twice weekly until death (AZC-CONT); two more groups of F1D hamsters were given the same AZC dose either for the first 75 days of SRI implantation (AZC-EARLY) or from 80 days after SRI placement until death (AZC-LATE). OB Hamsters were sacrificed at regular intervals from 62 to 189 days of SRI exposure. F1D Hamsters were sacrificed in groups after 120, 150, 180, and 220 days of SRI exposure. The bronchial mucosa at the SRI site was examined cytologically and histologically, as were the tumors that developed. Mean quantitative total cellular DNA values (QDNA) were measured by image analysis. For both varieties of hamster given AZC, QDNA values were higher in early carcinogenesis (CG) and lower in the late stage of CG than in hamsters that did not get AZC (P less than 0.001). QDNA values were lower in epidermoid than in non-epidermoid cancers (P less than 0.001); for both types of cancer, QDNA was lower in AZC-treated hamsters (P less than 0.01). Cancers induced under the influence of AZC included more epidermoid cancers (P less than 0.01) and were of a higher degree of differentiation (P less than 0.01) than those induced by BP alone, especially when AZC was given early in CG. There was no consistent relationship between QDNA and degree of differentiation in tumors. These differential effects of AZC given early during CG suggest that 1) for epidermoid bronchial CG, some of the molecular alterations involved in hyperploidy and in differentiation occur early in the sequential progression of carcinogenesis; and 2) for both epidermoid and non-epidermoid bronchial CG, the necessary changes must occur in a fixed sequence instead of as random events, until all needed changes have occurred.

Animals↗
PubMed1989

Isolation of colonic crypts that maintain structural and metabolic viability in vitro.

The aim of this study was to develop a method by which colonic epithelial cells can be isolated from resected mucosa or colonoscopic biopsy specimens and viability maintained in the short term. The principles of the technique are to digest the lamina propria from the epithelium with Dispase and collagenase, to disrupt the epithelium by trituration, and to purify the epithelial cells by seiving and differential sedimentation. Whole and partial crypts were isolated with consistently high purity of 93.5% +/- 1.2% (excluding red cells). Structural integrity was confirmed by light and electron microscopy, exclusion of trypan blue, minimal leakage of lactic dehydrogenase over 5 h (4.1% +/- 1.7%), and 51Cr leakage of less than 2% per hour over 16 h. Functional integrity was supported by continued deoxyribonucleic acid synthesis [( 3H]thymidine uptake) over 16 h and the formation of epithelial monolayer cultures on plastic. Thus, this simple method yields a highly enriched cell population that maintains high viability in vitro for at least 16 h. Such cells may be useful for the study of the biology of colonic epithelial cells.

Autoradiography↗
PubMed1989

A new case of deletion 1q42 syndrome.

We report a 1 8/12-year-old male with a de novo deletion of 1q42. The case is compared with 23 others from the literature. The clinical manifestations of our patient correspond with the phenotype of previous reports.

Chromosome Deletion↗
PubMed1989

[Primary lung cancer from biopsy material of the Pathomorphology Department of the Silesian Medical Academy in Zabrze].

An analysis was carried out of material biopsied during fiberoptic bronchoscopic examination of 289 patients suspected of lung malignant disorders were present more often in males. In the group of patients older than 40 years the most often diagnosed malignant process was squamous cell carcinoma. A high correlation of clinical suspicion of malignant process and histopathological diagnosis was found. A low rate of diagnosis of operable cases was found.

Adult↗
PubMed1987

Evidence of discontinuous transcription in the trypanosomatid Crithidia fasciculata.

In an effort to exploit the advantages of Crithidia fasciculata for detailed analysis of the mechanisms of discontinuous transcription in the trypanosomatid family, we have cloned, sequenced, and characterized the mini-exon gene repeat in Crithidia and mapped the termini of its primary transcript. We find that Crithidia contains approximately 500 mini-exon genes, present almost exclusively as tandemly repeated arrays on a single chromosome. Transcripts derived from these genes are approximately 90 bases in length with heterogeneity at both the 5' and 3' ends. Primer extension experiments reveal a putative splicing intermediate. Specific inhibition of in vitro translation of Crithidia mRNAs by an oligonucleotide complementary to the mini-exon suggests that all Crithidia mRNAs contain the mini-exon at their 5' termini. Comparison of mini-exon gene sequences from various trypanosomatids reveals several regions of conservation that imply functional constraints on the transcription of mini-exon genes and the processing of their transcripts.

Animals↗