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Biomedical subjects

A Bueno

Publications and source records attributed to A Bueno.

At least 19 recordsLinked to original sources
PubMed2001

Cdc6 cooperates with Sic1 and Hct1 to inactivate mitotic cyclin-dependent kinases.

Exit from mitosis requires the inactivation of mitotic cyclin-dependent kinases (CDKs). In the budding yeast, Saccharomyces cerevisiae, inactivation of CDKs during late mitosis involves degradation of B-type cyclins as well as direct inhibition of cyclin-CDK complexes by the CDK-inhibitor protein Sic1 (refs 1,2,3). Several striking similarities exist between Sic1 and Cdc6, a DNA replication factor essential for the formation of pre-replicative complexes at origins of DNA replication. Transcription of both genes is activated during late mitosis by a process dependent on Swi5 (ref. 10). Like Sic1, Cdc6 binds CDK complexes in vivo and downregulates them in vitro. Here we show that Cdc6, like Sic1, also contributes to inactivation of CDKs during late mitosis in S. cerevisiae. Deletion of the CDK-interacting domain of Cdc6 does not inhibit the function of origins of DNA replication during S phase, but instead causes a delay in mitotic exit; this delay is accentuated in the absence of Sic1 or of cyclin degradation. By contributing to mitotic exit and inactivation of CDKs, Cdc6 helps to create the conditions that are required for its subsequent role in the formation of pre-replicative complexes at origins of DNA replication.

Cdh1 Proteins↗
PubMed2001

Flp1, a fission yeast orthologue of the s. cerevisiae CDC14 gene, is not required for cyclin degradation or rum1p stabilisation at the end of mitosis.

In Saccharomyces cerevisiae, the phosphoprotein phosphatase Cdc14p plays a central role in exit from mitosis, by promoting B-type cyclin degradation and allowing accumulation of the cyclin-dependent kinase inhibitor Sic1p. Cdc14p is sequestered in the nucleolus during interphase, from where it is released at the end of mitosis, dependent upon mitotic exit network function. The CDC14 gene is essential and loss-of-function mutants arrest at the end of mitosis. We have identified a fission yeast orthologue of CDC14 through database searches. A Schizosaccharomyces pombe flp1 (cdc fourteen-like-phosphatase) null mutant is viable, divides at a reduced size and shows defects in septation. flp1p is not the essential effector of the S. pombe septation initiation network, but may potentiate signalling of the onset of septation. In contrast to S. cerevisiae Cdc14p, flp1p is not required for the accumulation or destruction of the B-type cyclin cdc13p, the cyclin-dependent kinase inhibitor rum1p, or for dephosphorylation of the APC/C specificity factor ste9p in G1. Like its budding yeast counterpart, flp1p is restricted to the nucleolus until mitosis, when it is dispersed through the nucleus. In contrast to S. cerevisiae Cdc14p, flp1p is also present on the mitotic spindle and contractile ring. The potential roles of flp1p in cell cycle control are discussed.

Cell Cycle Proteins↗
PubMed2000

The stability of the Cdc6 protein is regulated by cyclin-dependent kinase/cyclin B complexes in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae Cdc6 protein is necessary for the formation of prereplicative complexes that are a prerequisite for firing origins during DNA replication in the S phase. In budding yeast, the presence of Cdc6 protein is normally restricted to the G(1) phase of the cell cycle, at least partly because of its proteolytic degradation in the late G(1)/early S phase. Here we show that a Cdc28-dependent mechanism targets p57(CDC6) for degradation in mitotic-arrested budding yeast cells. Consistent with this observation, Cdc6-7 and Cdc6-8 proteins, mutants lacking Cdc28 phosphorylation sites, are stabilized relative to wild-type Cdc6. Our data also suggest a correlation between the absence of Cdc28/Clb kinase activity and Cdc6 protein stabilization, because a drop in Cdc28/Clb-associated kinase activity allows mitotic-arrested cells to accumulate Cdc6 protein. Finally, we also show that cdc28 temperature-sensitive G(1) mutants accumulate Cdc6 protein because of a post-transcriptional mechanism. Our data suggest that budding yeast cells target Cdc6 for degradation through a Cdc28-dependent mechanism in each cell cycle.

Base Sequence↗
PubMed1999

The Cdc6 protein is ubiquitinated in vivo for proteolysis in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae Cdc6 protein is necessary for the formation of pre-replicative complexes that are required for firing DNA replication at origins at the beginning of S phase. Cdc6p protein levels oscillate during the cell cycle. In a normal cell cycle the presence of this protein is restricted to G1, partly because the CDC6 gene is transcribed only during G1 and partly because the Cdc6p protein is rapidly degraded at late G1/early S phase. We report here that the Cdc6p protein is degraded in a Cdc4-dependent manner, suggesting that phosphorylated Cdc6 is specifically recognized by the ubiquitin-mediated proteolysis machinery. Indeed, we have found that Cdc6 is ubiquitinated in vivo and degraded by a Cdc4-dependent mechanism. Our data, together with previous observations regarding Cdc6 stability, suggest that under physiological conditions budding yeast cells degrade ubiquitinated Cdc6 every cell cycle at the beginning of S phase.

Cell Cycle Proteins↗
PubMed1999

Functionally homologous DNA replication genes in fission and budding yeast.

The cdc18(+) gene of the fission yeast Schizosaccharomyces pombe is involved in the initiation of DNA replication as well as in coupling the S phase to mitosis. In this work, we show that the Saccharomyces cerevisiae CDC6 gene complements cdc18-K46 ts and cdc18 deletion mutant S. pombe strains. The budding yeast gene suppresses both the initiation and the checkpoint defects associated with the lack of cdc18(+). The Cdc6 protein interacts in vivo with Cdc2 kinase complexes. Interestingly, Cdc6 is an in vitro substrate for Cdc13/Cdc2 and Cig1/Cdc2, but not for Cig2/Cdc2-associated kinases. Overexpression of Cdc6 in fission yeast induces multiple rounds of S-phase in the absence of mitosis and cell division. This CDC6-dependent continuous DNA synthesis phenotype is independent of the presence of a functional cdc18(+) gene product and, significantly, requires only Cig2/Cdc2-associated kinase activity. Finally, these S. pombe over-replicating cells do not require any protein synthesis other than that of Cdc6. Our data strongly suggest that CDC6 and cdc18(+) are functional homologues and also support the idea that controls restricting genome duplication diverge in fission and budding yeast.

Base Sequence↗
PubMed1999

[Fibrous craniofacial dysplasia].

A case report of fibrous dysplasia affecting only the craniofacial right side, in a 56-year-old woman, seen in our outpatients Department suffering from fronto-orbital headache and subjective hypoacusis of the right side, besides a syndrome of dizziness of 6 years development.

Diagnosis, Differential↗
PubMed1998

DNA interaction and cytostatic activity of the new liver organotropic complex of cisplatin with glycocholic acid: Bamet-R2.

The aim of this study was to investigate the ability of the new liver organotropic complex of cisplatin with glycocholate (GC), Bamet-R2, to interact with DNA, inhibit its replication and hence reduce tumor-cell proliferation. Changes in the electrophoretic mobility of the open and covalently closed circular forms of the pUC18 plasmid DNA from Escherichia coli, a shift in the denaturation temperature of double-stranded DNA, and ethidium-bromide displacement from DNA binding, were induced by Bamet-R2 and cisplatin, but not by GC. Neutral-red retention was used to measure the number of living cells in culture after long-term (72-hr) exposure to these compounds and to evaluate the effect on cell viability after short-term (6-hr) exposure. Bamet-R2 and cisplatin, but not GC, induced significant inhibition of cell growth. This effect ranged from mild to strong, depending upon the sensitivity of the different cell types as follows: cisplatin, rat hepatocytes in primary culture < rat hepatoma McA-RH7777 cells (rH) < human colon carcinoma LS 174T cells (hCC) < mouse hepatoma Hepa 1-6 cells (mH); Bamet-R2, rat hepatocytes < mH approximately equal to hCC < rH. DNA synthesis was measured by radiolabeled-thymidine incorporation into DNA. Bamet-R2 and cisplatin, but not GC, significantly inhibited the rate of DNA synthesis by these cells. After short-term exposure to Bamet-R2 or GC, no acute cell toxicity was observed, except on hCC cells. By contrast, acute toxicity was induced by cisplatin for all cell types studied. The in vivo anti-tumoral effect was investigated in 3 different strains of mice following s.c. implantation of tumor cells (mouse sarcoma S-18011 cells in Swiss and B6 mice and hCC cells in nude mice). In all 3 models, tumor growth was inhibited by Bamet-R2 and cisplatin to a similar degree. However, signs of toxicity (increases in blood urea concentrations and decreases in packed blood cell volume and in liver, kidney and body weight) and a reduction in survival rate were observed only during cisplatin administration. In sum, these results indicate that this bile-acid derivative can be considered as a cytostatic drug whose potential usefulness deserves further investigation.

Animals↗
PubMed1997

Exercise-induced changes in circulating growth factors with cyclic variation in plasma estradiol in women.

The effect of 10 min of high-intensity cycling exercise on circulating growth hormone (GH), insulin-like growth factors I and II (IGF-I and -II), and insulin-like growth factor binding protein 3 (IGF BP-3) was studied in nine eumenorrheic women (age 19-48 yr) at two different phases of the menstrual cycle. Tests were performed on separate mornings corresponding to the follicular phase and to the periovulatory phase of the menstrual cycle, during which plasma levels of endogenous estradiol (E2) were relatively low (272 +/- 59 pmol/l) and high (1,112 +/- 407 pmol/l), respectively. GH increased significantly in response to exercise under both E2 conditions. Plasma GH before exercise (2.73 +/- 2.48 vs. 1.71 +/- 2.09 micrograms/l) and total GH over 10 min of exercise and 1-h recovery (324 +/- 199 vs. 197 +/- 163 ng) were both significantly greater for periovulatory phase than for follicular phase studies. IGF-I, but not IGF-II, increased acutely after exercise. IGF BP-3, assayed by radioimmunoassay, was not significantly different at preexercise, and exercise, or at 30-min recovery time points and was not different between the two study days. When assayed by Western blot, however, there was a significant increase in IGF BP-3 30 min after exercise for the periovulatory study. These findings indicate that the modulation of GH secretion associated with menstrual cycle variations in circulating E2 affects GH measured after exercise, at least in part, by an increase in baseline levels. The acute increase in IGF-I induced by exercise appears to be independent of the GH response and is not affected by menstrual cycle timing.

Adult↗
PubMed1996

Peroneal arteriovenous fistula as a complication of above-knee femoropopliteal polytetrafluorethylene graft thrombectomy with the Fogarty catheter.

The Fogarty catheter is an invaluable tool in the surgical practice of a vascular surgeon. Arteriovenous fistula is an unusual but potentially dangerous complication of its use. We present the case of a man who suffered a peroneal arteriovenous fistula as a result of an above-knee femoropopliteal polytetrafluorethylene graft thrombectomy. As the fistula compromised the viability of the extremity, surgical correction was warranted. It was performed without further complications to the patient. The few cases reported in the literature are reviewed. We conclude that this complication should be repaired as soon as it is detected.

Aged↗
PubMed1995

[Knowledge of the nursing consultation in primary health care].

OBJECTIVE: To find how much is known about the nursing surgeries in our health district. To compare the level of knowledge/use between the population covered and those with medical records. SETTING: Las Fuentes Norte health district, Zaragoza. PARTICIPANTS: Sample A (population): systematic random sampling of families, selecting 100 homes from the telephone book. 212 interviews with people over 18. Sample B (institutional). Simple and proportional random sampling of 100 patients with records at the centre. DESIGN: A crossover descriptive study using a telephone survey. MEASUREMENTS AND MAIN RESULTS: 86.3% of sample A had attended the centre on some occasion since its opening. 42% of sample A and 60% of B knew that the nursing surgeries existed. 27% of A and 46% of B had used it. By age, in sample A those over 65 used it more; in B, those between 51 and 65. The most widely known nursing activities were: taking blood pressure (20.3% in sample A and 33% in B); weight monitoring (13.7% and 20%, respectively). 37.7% of sample A knew their nurse; 60% of B. CONCLUSIONS: The nurse is still mainly identified with activities he/she has "classically" performed, like taking blood pressure and weight. Other more recent nursing activities, such as monitoring drug-dietetic treatments, preventive activities, check-ups of healthy children etc., are still not perceived by the general population.

Adolescent↗
PubMed1994

ntf1+ encodes a 6-cysteine zinc finger-containing transcription factor that regulates the nmt1 promoter in fission yeast.

The nmt1+ gene of the fission yeast Schizosaccharomyces pombe is subject to transcriptional repression mediated by thiamine. The promoter of nmt1+ has been used to construct a series of vectors that are now commonly used for the regulated expression of genes in S. pombe. In this report, we described ntf1+, a gene involved in regulating nmt1+ expression. The ntf1+ gene was cloned in a high copy suppressor screen that utilized a construct, nmt1:wee1+, in which expression of the mitotic inhibitor Wee1 tyrosine kinase was placed under the control of the nmt1 promoter. ntf1+ encodes a 706-amino acid protein that shares substantial homology with a family of Cys6 zinc finger-containing transcription factors typified by GAL4 from Saccharomyces cerevisiae. Increased gene dosage of ntf1+ greatly increases both the repressed and derepressed activity of the nmt1 promoter. Cells having a disrupted version of ntf1+ are viable thiamine prototrophs, but basal expression from the nmt1 promoter is greatly reduced. These data demonstrate that Ntf1 plays an important role in regulating nmt1 expression.

Amino Acid Sequence↗
PubMed1994

HIV-transmission knowledge in drug users from outpatient facilities in Spain. A national survey.

Knowledge of AIDS and its transmission was studied in patients undergoing drug-dependence treatment for opiates and/or cocaine. The study area included all of Spain and was carried out via a questionnaire assessing information about risk practices, HIV serostatus, etc, and 13 true or false questions concerning HIV-transmission knowledge. The main purpose of the present study was to analyse the relationship between the level of information found in patients and factors potentially related to it, including the practice of high-risk activities for HIV transmission, the sources of information and behaviour modification. Findings indicate that poor information was associated with the use of non-sterile needles, anal-penis sexual relations, non-use of condoms, lack of preventive measures in daily cohabitation, and lack of previous drug-dependence treatment. Determining factors of being well-informed were a high level of education, a longer duration of intravenous drug use, and contact with the Health Service as a source of information. These findings partially support the need to implement programs aimed at improving knowledge about HIV in the population of drug users.

Acquired Immunodeficiency Syndrome↗
PubMed1994

DNA content in non-Hodgkin's lymphoma. Comparison between flow cytometry and cytogenetics in fresh and paraffin-embedded tissue.

DNA content of 36-non-Hodgkin's lymphomas was analyzed by flow cytometry (FCM) and cytogenetics (CG), 21 in fresh and 15 in paraffin-embedded tissue. The results of both techniques were coincident in 60% of the fresh tissue samples and in 45% of the paraffin-embedded ones, the reason for this difference could be the poor resolution of DNA histograms from paraffin-embedded tissue. All samples judged as aneuploid by FCM were aneuploid also by CG. Some samples with a hyperdiploid population by CG gave a diploid population by FCM with a 'false' high DNA-synthesis (S) fraction. From a technical point of view, CG and FCM have to be performed on the same fresh tissue.

Cell Cycle↗
PubMed1993

Two fission yeast B-type cyclins, cig2 and Cdc13, have different functions in mitosis.

Cyclin B interacts with Cdc2 kinase to induce cell cycle events, particularly those of mitosis. The existence of cyclin B subtypes in several species has been known for some time, leading to speculation that key events of mitosis may be carried out by distinct functional classes of Cdc2/cyclin B. We report the discovery of cig2, a third B-type cyclin gene in Schizosaccharomyces pombe. Disruption of cig2 delays the onset of mitosis, to the degree that a cig2 null allele rescues mitotic catastrophe mutants, including those that are unable to carry out the inhibitory tyrosyl phosphorylation of Cdc2 kinase. Consistent with this, a cig2 null allele exhibits synthetic lethal interactions with cdc25ts and cdc2ts mutations. Mitotic phenotypes caused by disruption of cig2 are not reversed by increased production of Cdc13, the other fission yeast B-type cyclin that functions in mitosis. Likewise, a cdc13ts mutation is not rescued by increased gene dosage of cig2+. These data indicate that Cdc13 and Cig2 interact with Cdc2 to carry out different functions in mitosis. We suggest that some cyclin B subtypes found in other species, including humans, are also likely to have distinct, nonoverlapping functions in mitosis.

Amino Acid Sequence↗
PubMed1993

Influence of socioeconomic and health care development on infant and perinatal mortality in Spain 1975-86.

STUDY OBJECTIVE: This study aimed to analyse the influence of social, economic, and health development on infant and perinatal mortality in Spain between 1975 and 1986, and to identify possible changes in these relationships over time. DESIGN: Study of the association between mortality and a range of variables. SETTING: 50 Spanish provinces. MEASUREMENTS AND MAIN RESULTS: Mean infant and perinatal mortality were estimated for two periods--1975-8 and 1983-6. Social, economic, and health care indicators were collected as independent variables for these two periods. The rates of variation between periods were estimated for each variable. Multiple linear regression models were used to define the association between infant and perinatal mortality and their respective rate of variation with the former indicators. Mean familial income was the main predictive factor for infant and perinatal mortality in the first period but in the second period health care indicators were more relevant. CONCLUSIONS: The reduction in Spanish infant and perinatal mortality over the period can be attributed mainly to the improvement in prenatal and neonatal health care in Spain in recent years, while economic factors seem less important.

Birth Rate↗
PubMed1993

[Biology of secondary nodal follicular b-lymphomas. A patho-dynamic study].

PURPOSE: To assess the aggressivity factors and tumour prognosis in a series of non-Hodgkin lymphomas by the use of computer-quantified specific antibodies and flow cytometry. PATIENTS AND METHODS: Sixty-one cases of follicular B-cell lymphoma: 34 of the germinal centre (24 centroblastic-centrocytic, CB-CC, and 10 centroblastic, CC) and 27 of the follicular cortex (FCL), were studied. All the cases had been diagnosed between 1971 and 1992 at the Pathology Department of the Fundación Jiménez Díaz. Morphologic and immunophenotype diagnosis was made on each case. Tumour proliferation studies were performed after labelling nuclei with proliferent nucleic acid-associated protein (PC 10); the positive nuclear areas were later quantified in a CAS-200 image analyser by means of proliferation programmes (PI) and nuclear receptors (ER). A flow cytometry study of ploidy was carried out on each case. The values attained were correlated with survival in months. The Wilcoxon's test for independent variables was used for the statistical study. RESULTS: The PI programme showed lowest proliferation for FCL (7.4%) followed by intermediate proliferation in CB-CC (16.9%) and high proliferation in CB (31.7%). The PC-10 results attained with both PI and ER programmes showed statistically significant correlation (p < 0.01). The correlation between ploidy, as quantified by flow cytometry, and survival showed statistically significant differences between diploid and aneuploid cases (p < 0.01); similar findings apply for diploids and diploids with high synthesis phase (p < 0.01). CONCLUSION: These findings support the usefulness of cell kinetics studies in lymphoma, and contribute to validate different evolutive patterns in accordance with the histologic subtype.

Biomarkers, Tumor↗
PubMed1992

Dual functions of CDC6: a yeast protein required for DNA replication also inhibits nuclear division.

The Saccharomyces cerevisiae gene CDC6, whose protein product is required for DNA replication, is transcribed only in late G1 and S phases. We have discovered a critical reason why CDC6 expression is regulated in this fashion. Constitutive CDC6 transcription greatly delayed the initiation of M phase without effecting the G1-S transition or growth rate. This occurred in both fission and budding yeasts. The CDC6-induced M phase delay was dependent on the wee1/mik1 mitotic inhibitor kinases and was greatly accentuated in strains defective for the cdc25/MIH1 mitotic inducer phosphatases, indicating that CDC6 indirectly inhibits activation of the p34cdc2/CDC28 M phase kinase. Thus CDC6 appears to have an important and perhaps unique dual role in S phase, it is first required for the initiation of DNA replication and then actively participates in the suppression of nuclear division.

Base Sequence↗