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Biomedical subjects

C Ramírez

Publications and source records attributed to C Ramírez.

At least 55 records · Page 3Linked to original sources
PubMed1996

Delaying and extending sleep during weekends: sleep recovery or circadian effect?

There is a well-known tendency to delay and prolong our sleep during weekends (Saturday and Sunday), with an advance and reduction of sleep during workdays (Monday to Friday). The objective of this work was to determine if the changes of sleep during weekends are produced by a partial sleep deprivation or a lack of entraining of circadian rhythms to an advanced phase, during workdays. The subjects were 52 undergraduate female students, mean age = 17.5 years, SD = 1.32. All students attended school following a regular schedule, from Monday to Friday. Two groups of students were studied: one attended school from 07:00 to 12:00 h (morning group, n = 30); the other attended school from 14:00 to 18:00 (afternoon group, n = 22). None of the students worked or was engaged in other activity with a fixed schedule. All kept a sleep-wake diary for 2 weeks, in which they recorded their bedtimes, wakeup times, and sleep-onset latencies. The morning group delayed 47.4 min [t(29) = 4.72, p < 0.0001] and prolonged their sleep 118.2 min [t(29) = 9.4, p < 0.0001] during weekends. Although the afternoon group had the opportunity to maintain a delayed phase and a long sleep time throughout the week, they delayed their bedtime by 24 min [t(21) = 2.99, p < 0.01] during weekends, without changing their sleep duration. The findings suggest that the prolonged sleep during weekends is due to reduction of sleep during workdays, whereas the delay of bedtime seems to be associated with a tendency of the human circadian system to maintain a delayed phase with respect to the solar daylight period.

Activities of Daily Living↗
PubMed1995

Gingival overgrowth induced by nifedipine and cyclosporin A. Clinical and morphometric study with image analysis.

In this study, we developed a quantitative method with digital image analysis to evaluate the degree of gingival overgrowth (GO), and compared GO in kidney transplant patients treated with cyclosporin A (CsA) (n = 21) or CsA+nifedipine (n = 8) and a group of healthy controls (n = 30). The method was reproducible and reliable. Our findings showed significant differences in papillary and gingival surface between controls and transplant patients treated with GO inducers. Gingival overgrowth index also differed significantly between controls and each patient group (p < 0.01, Kruskal-Wallis test). The administration of the calcium channel blocker nifedipine potentiated the adverse effect of CsA: comparison of the morphometric findings revealed significant differences between patients treated with CsA alone and CsA+nifedipine in papillary area, dental area, and GO index (p < 0.01, Mann-Whitney U-test). We conclude that the method of image analysis we developed is useful in assessing the degree of GO.

Adult↗
PubMed1995

Influence of intrarenal deposits of ciclosporin A on acute renal transplant rejection.

Immunohistochemical techniques were used to study the presence of ciclosporin A (CsA) and leukocyte subsets in 36 posttransplant renal biopsy specimens histologically diagnosed as acute graft rejection. Glomeruli from patients with CsA deposits contained more leukocytes (p < 0.05) than glomeruli from tissues without deposits. In contrast, the interstitium from patients without deposits contained significantly more B lymphocytes than interstitia from kidneys with CsA deposits. In both glomeruli and interstitia, the CD4/CD8 ratios were higher in tissues without deposits, although the difference was not significant. The plasma levels of creatinine increased with the intensity of renal CsA deposits, and significantly more patients on hemodialysis had deposits as compared with patients not on hemodialysis. Our findings suggest two types of acute nonvascular rejection: (1) predominantly interstitial, with a good prognosis, characterized by low numbers of intrarenal CsA deposits and a predominance of B lymphocytes and (2) predominantly glomerular, with a poor prognosis, characterized by high levels of intrarenal CsA and a predominance of CD8-positive cells and macrophages.

Acute Disease↗
PubMed1995

Relationship between P-glycoprotein expression and cyclosporin A in kidney. An immunohistological and cell culture study.

P-glycoprotein (P-gp), encoded in humans by the mdr-1 gene, acts physiologically as an efflux pump to expel hydrophobic substances from cells. This glycoprotein is closely related to multidrug resistance in tumor cells and can be modulated by cyclosporin A (CsA). We investigated the relationship between CsA and P-gp in 52 renal allograft biopsies and in cultures of Madin-Darby canine kidney (MDCK) renal tubule cells to determine whether the intrarenal accumulation of CsA or chronic stimulation with the drug modified the expression of P-gp. Expression of P-gp and CsA was analyzed by immunohistochemistry. Immunostaining was evaluated semiquantitatively. Modulation of P-gp in MDCK cells after chronic stimulation with CsA for 7, 30, and 60 days was analyzed by flow cytometry. P-gp and CsA immunostaining in renal post-transplant biopsies showed considerable overlap in all cases (Spearman's test, r = 0.577, P < 0.001). After 7 days in vitro, the number of cells expressing P-gp increased progressively; a further increase in mean fluorescence was found after 60 days (P < 0.001, Student's t-test). Our findings suggest that in non-neoplastic cells, CsA may stimulate P-gp as a mechanism of detoxification. Individual differences in the adaptive responses to glycoprotein may be responsible for the appearance of nephrotoxicity or a CsA-resistant rejection reaction in cases of overexpression on lymphocytes and macrophages.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Structure and transcription of the L11-L1-L10-L12 ribosomal protein gene operon from the extreme thermophilic archaeon Sulfolobus acidocaldarius.

We have cloned and sequenced four ribosomal protein genes from the extreme thermophilic archaeon Sulfolobus acidocaldarius P1. These genes code for proteins equivalent to L11, L1, L10 and L12 from Escherichia coli. The genes for the Sulfolobus L11, L1, L10 and L12 proteins are arranged in the same order as the equivalent genes in E. coli, i.e. L11-L1-L10-L12, and are transcribed as a single unit. Sequences resembling the consensus sequence for archaeal promoters have been detected upstream of the transcription initiation site. Transcription ends at several sites following a pyrimidine-rich region. The genes for proteins L11, L10 and L1 start with unusual initiation codons: GUG in the case of the L1 and L10 genes; and UUG in the case of L11. There are overlapping stop/start codons between the L11 and L1 genes, and between the L1 and L10, suggesting that the translation of the four genes might be coupled as in the bacteria.

Amino Acid Sequence↗
PubMed1994

Further butenolides from the Caribbean octocoral Pterogorgia citrina.

Seven fatty acid derivatives containing one or two butenolide moieties along with ancepsenolide [1], a known bis-butenolide of marine origin, were isolated from the Caribbean gorgonian Pterogorgia citrina. The structures of the new metabolites were elucidated on the basis of spectroscopic data and were confirmed upon chemical conversion to either ancepsenolide or to its homolog, homoancepsenolide [4].

4-Butyrolactone↗
PubMed1994

[Spontaneous uterine rupture associated with placenta increta in a primipara].

An infrequent clinical case with spontaneous uterine rupture in a 14 weeks primigesta with symptoms and signs of hemoperitoneum with hypovolemic shock. The emergency laparotomy revealed 2,000 ml of hemoperitoneum and a rupture of depth of 5 cm the diameter with fetus alive in the inner. Ovular emptying and histerorraphya were carried out. Biopsy in the edge of the uterine rupture revealed placenta increta.

Adult↗
PubMed1993

A bifunctional affinity linker to couple antibodies to cellulose.

We have constructed a fusion protein between the staphylococcal A protein and the cellulose binding domain of an exoglucanase (Cex) from Cellulomonas fimi that can be directly immobilized on cellulose while retaining its capacity to bind immunoglobulin G molecules. The cellulose domain provides binding that does not interfere with the biological activity of the fusion partner, does not involve hazardous chemicals and the matrix does not need to be chemically activated which reduces its cost. We have tested some of the possible applications of the fusion protein and show that it can be used in immunoassays, affinity chromatography and immunoprecipitations.

Antibodies↗
PubMed1993

[Candida albicans meningitis in 2 parenteral drug addicts. Review of the literature].

BACKGROUND: HIV infection and parenteral drug abuse (PDA) are frequently associated conditions. Both are at increased risk of developing specific types of Candida infections. Localized CNS infection is an exceptional finding. METHODS: We report two cases of meningitis in PDA due to Candida albicans--one of them HIV positive, and review the literature emphasizing the characteristics of 8 HIV positive patients 4 of them PDA. RESULTS: Most frequent presentation symptoms were fever and headache for more than two weeks. Three patients were found normal on neurologic examination. In two cases CT scan showed hydrocephalus. In one case CNS infarcts were demonstrated on MRI. Median CSF cell counts were 109, mostly lymphocytic. Two cases had elevated adenosine deaminase levels in CSF. Two cases were treated with fluconazole, one improved and the other was cured. Four patients died due to the infection, one of them received no specific treatment. CONCLUSIONS: Candida meningitis can be a manifestation of HIV related immunosuppression. Clinical and CSF findings are mild. Mortality is high. Probably a maintenance therapy is required.

Adult↗
PubMed1991

A gene in the archaebacterium Sulfolobus solfataricus that codes for a protein equivalent to the alpha subunits of the signal recognition particle receptor in eukaryotes.

We have sequenced a gene in the archaebacterium Sulfolobus solfataricus that codes for a protein that shows sequence similarity to the alpha subunit of the signal recognition particle receptor or docking protein in eukaryotes and the product of the ftsY gene in Escherichia coli. Comparison of the Sulfolobus 'docking protein' with its eukaryotic and eubacterial counterparts showed that the region of highest sequence similarity corresponds to a GTP-binding site. The presence of this gene in archaebacteria suggests that some of the components involved in protein transport have been conserved in the three kingdoms.

Amino Acid Sequence↗
PubMed1988

On the early evolution of RNA polymerase.

The lines of evidence suggesting that RNA preceded double-stranded DNA as an informational macromolecule are briefly reviewed. RNA polymerase is hypothesized to have been one of the earliest proteins to appear. It is argued that an important vestige of the original enzyme is found in the contemporary eubacterial beta' subunit of DNA-dependent RNA polymerase and its homologues among the archaebacterial and eukaryotic enzymes. The evidence that supports a catalytic role in replicase activity of this polypeptide is reviewed. It is suggested that several characteristics of the Escherichia coli transcriptional apparatus are relatively recent evolutionary developments. The phylogenetic importance of the eubacterial beta' subunit from RNA polymerase and its homologues is emphasized, because it allows the study of the evolutionary relationships of the major cellular lines (eubacteria, archaebacteria, and eukaryotes) as well as of some viral lineages.

Amino Acid Sequence↗
PubMed1987

A significant geographical area for the study of the epidemiological and ecological aspect of Mediterranean sporothricosis.

Two cases of sporothricosis originating from the same geographical area (Province of Barcelona) are described, including the circumstances of infection and the isolation of a wild strain of Sporothrix schenckii at the same locality. This finding could classify this particular area as a zone of interest in the epidemiological and ecological study of the mediterranean sporothricosis.

Adolescent↗
PubMed1985

Protocol variations and their influence on the final outcome: critical review of the split-course base of tongue study of the RTOG.

A critical review of the protocol variations in an RTOG prospective randomized multi-institutional clinical trial has been conducted. The objective of the review was to identify variables that might have affected the results of the study. Compliance with general guidelines and specific technical treatment parameters of the Split-Course Radiation Therapy Protocol for Carcinoma of the Base of the Tongue (RTOG #71-02) was analyzed. A +/- 5% variation of the time-dose-fractionation factors, using the NSD and TDF formulae and their respective protocol ratios (ratio between actual case NSD and TDF level and what the protocol recommended), has been defined as fully acceptable. Seventy-two percent of the 141 study cases were within this category. Minor variation has been defined as one resulting in a +/- 6% to +/- 15% deviation from the study values (15.3% of cases). Major and unacceptable variation was a deviation of +/- 16% or more from the research plan (12.7% of cases). After identifying the different variations and correlating them with the clinical results, we conclude that these deviations did not affect the final results to a significant or identifiable degree.

Clinical Trials as Topic↗