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Biomedical subjects

S Robles

Publications and source records attributed to S Robles.

13 recordsLinked to original sources
PubMed2005

A critical assessment of screening methods for cervical neoplasia.

The objective of cervical cancer screening is to reduce cervical cancer incidence and mortality by detecting and treating precancerous lesions. Conventional cytology is the most widely used cervical cancer screening test. Although cytology has been effective in reducing the incidence of and mortality from cervical cancer in developed countries in both opportunistic and--more dramatically--organized national programs, it has been less successful and largely ineffective in reducing disease burden in low-resource settings where it has been implemented. Liquid-based cytology, testing for infection with oncogenic types of human papillomaviruses, visual inspection with 3-5% acetic acid, magnified visual inspection with acetic acid, and visual inspection with Lugol's iodine have been evaluated as alternative tests. Their test characteristics, and the applications and limitations in screening, are discussed with an emphasis on the work of the Alliance for Cervical Cancer Prevention over the past 5 years.

Cytological Techniques↗
PubMed2005

Decrease of selective immunoglobulin E response to amoxicillin despite repeated administration of benzylpenicillin and penicillin V.

BACKGROUND: Subjects with IgE responses to betalactams can develop selective or cross-reactive responses after the administration of penicillin derivatives. After the reaction, however, the hapten induces a boosting phenomenon, which may increase the titre and the affinity of the antibody, with the resulting risk of developing allergic reactions to other penicillins. OBJECTIVE: To determine in subjects with selective responses to amoxicillin (AX) and good tolerance to benzylpenicillin (BP) and penicillin V (PV) whether the administration of these compounds induced any change in specificity, measured by either skin or in vitro testing, which could predict the appearance of cross-reactivity. METHODS: Ten subjects with a selective response to AX were followed-up for 2 years with the periodic administration of penicillin G and V (Group A) and compared with another group composed of 10 persons with identical clinical characteristics but without repeated penicillin administration (Group B). Periodic in vitro and in vivo measurements of specific IgE antibodies were performed at 6-month intervals. Patients were randomized to Group A or B according to their order of inclusion. RESULTS: In both groups, skin test reactivity tended to decrease, and although greater in Group A, the difference was not significant compared with Group B. Median RAST values also decreased over time and showed no differences in the exposed group compared with the controls. One patient in Group A became positive to benzylpenicilloyl (BPO), despite becoming negative to AX. CONCLUSION: Subjects with selective IgE responses to side-chain-specific determinants seem to become negative, with no influence from subsequent administration of a closely related penicillin.

Adolescent↗
PubMed2004

Perceived barriers and benefits to cervical cancer screening in Latin America.

BACKGROUND: This article describes the results of studies on the barriers and benefits of cervical cancer screening from the perspective of women, men, and health providers in five Latin American countries and compares them to other findings from the literature. METHODS: Five separate qualitative studies (focus groups and interviews) were conducted among low-income women in Venezuela, Ecuador, Mexico, El Salvador, and Peru regarding barriers and benefits of cervical cancer screening. Views from health providers and men were also included. RESULTS: The main barriers identified by all participants are accessibility and availability of quality services, facilities that lack comfort and privacy, costs, and courtesy of providers, which interact with poor service delivery. Barriers that pertain to women's beliefs are anxiety borne by women awaiting test results, associated with negligence and fear of cancer (although not to a particular cancer or a particular procedure). Benefits of screening are peace of mind and being in control of their health, which then enable other life activities to continue unhindered. CONCLUSIONS: Except for the accessibility and availability of quality services, these results are consistent with findings from other studies in developed and developing countries. Barriers could be lifted if health service delivery was enhanced, for instance, through quality improvement techniques that are available at low cost. Women's anxiety over test results still needs to be further assessed to devise risk communication strategies that take into account broader cultural frameworks. It is to be noted that such strategies should permeate the way health services are provided for cervical cancer prevention regardless of the specific test used. Vulnerability perceived by low-income women with respect to their capacity to cope with diseases and trust the health services and how this affects their perceptions of risk and their behaviors have not been studied as yet.

Adult↗
PubMed2001

A tool for assessing the usefulness of prevalence studies done for surveillance purposes: the example of hypertension.

Every year dozens of cross-sectional studies are carried out that estimate the prevalence of risk factors for chronic noncommunicable diseases. Given that, there is potentially a large amount of information that could be extremely useful for risk factor surveillance. However, there are good reasons to question the methodological rigor and the reliability of the results coming from many of these studies. The potential benefits of the data are curtailed by the studies' shortcomings, in part often because there is no clear and explicit methodological information providing the details needed to assess the procedures that were actually used, as well as a failure to apply a uniform methodology that would allow comparisons over time or across studies. This paper is intended to be both a didactic and practical tool. It describes the construction of an instrument for assessing the usefulness of prevalence studies done within the context of surveillance activities, using the example of hypertension. The paper discusses and illustrates the most common pitfalls found with prevalence studies, and it also offers methodological standards that can guide future prevalence studies as well as stimulate future research efforts in this area.

Cross-Sectional Studies↗
PubMed2001

Prevalence estimates for hypertension in Latin America and the Caribbean: are they useful for surveillance?

OBJECTIVE: To apply a recently proposed model and assessment tool created by the authors for critically evaluating the data available on the prevalence of hypertension in LAC and assessing their usefulness for surveillance. METHODS: A bibliographic search to identify all publications that estimated the prevalence of hypertension was performed. Each of the papers located was assessed using a critical appraisal tool. RESULTS: Of the 58 studies published between 1966 and 2000, only 28 of them (48%) met the critical threshold to be considered useful for surveillance purposes. The distribution of the 28 studies in terms of their usefulness for surveillance was as follows: minimally useful, 16 studies; useful, 8 studies; and very useful, 4 studies. Several methodological shortcomings were identified, from inadequate sampling procedures and sample size to the poor quality of the primary data for planning purposes. DISCUSSION: Published studies on the prevalence of hypertension in Latin America and the Caribbean have, as a whole, limited usefulness for surveillance activities.

Caribbean Region↗
PubMed2001

[An intervention to improve diabetes control in Chile].

OBJECTIVE: Previous research has shown that controlling blood glucose improves short-term and long-term outcomes among patients who have either type 1 or type 2 diabetes. The objective of this study was to investigate, in a developing country, the effectiveness of an intervention that included patient education, self-monitoring of blood glucose, and determination of the level of glycosylated hemoglobin (HbA1c). METHODS: The patients were grouped into three categories, taking into account such clinical manifestations as the duration of their diabetes, its treatment, and their hospitalization history. After the inclusion and exclusion criteria were applied, the persons were randomly assigned to two groups. One group (210 patients) received the educational intervention, and the control group (206 patients) received customary care. The intervention group received educational information needed for self-monitoring of blood glucose and for the self-evaluation of positive and negative behaviors related to metabolic control of the disease. RESULTS: The two groups were similar with respect to age (mean of 52.3 and 50.5 years) and to the proportion of patients with type 1 diabetes (13.8% and 16.0%). There were no initial differences in the average concentration of HbA1c in the two groups (8.9% +/- 0.1% and 8.9% +/- 1.4%). A total of 50 persons dropped out of the study, 14.8% of those in the intervention group and 9.2% of those in the control group. In the intervention group, compliance with dietary recommendations increased by 43.5%, from 57.5% at the beginning of the study to 82.5% at the end (P < 0.001); in the control group there was also a change but it was not significant. Although patients with a high initial HbA1c concentration were underrepresented in this study, the average HbA1c concentration declined significantly in the intervention group (-0.4% +/- 1.1%, P = 0.001) but not in the control group (-0.1% +/- 0.1%). CONCLUSIONS: In one developing country, educating patients about diabetes helped improve metabolic control, a fact that can be attributed mainly to the intervention's positive impact on those persons' diet.

Adolescent↗
PubMed2000

Sulfite-reducing clostridia in the sediment of a high mountain lake (Laguna Grande, Gredos, Spain) as indicators of fecal pollution.

We studied the vertical distribution of sulfite-reducing clostridia in the sediment of a Spanish high-mountain lagoon (Laguna Grande de Gredos, central Spain), with optimal sediment characteristics (temperature < 20 degrees C) to maintain spores without growing. This allowed us to assess the original numbers of sulfite-reducing clostridia endospores settled, without postdepositional growing. Sulfite-reducing clostridia are normal inhabitants of the intestinal microbiota of humans and other mammals. These microorganisms may form endospores, which allow the bacteria to survive in almost any habitat, either terrestrial or aquatic, waiting for favorable conditions for growth. Sulfite-reducing clostridia could be suitable indicators of past human pollution because they have a great longevity in natural habitats and they cannot multiply at temperatures below 20 degrees C or in the presence of O2. We found a great increase in the numbers of clostridia (expressed as colony-forming units per gram [CFU/g] of dry weight of sediment) since the 1970s, which reflects the rise of human pressure caused by the practice of outdoor activities. Clostridia CFU/g rose dramatically after the faulty operation of the depuration system of a mountain refuge built close to the lagoon. We compared the vertical distribution of clostridia CFU/g from Laguna Grande sediments with those from a neighbor lagoon (Laguna Cimera), which showed less tourist pressure and no direct disposal of sewage. Finally, we agree with the usefulness of the numbers of sulfite-reducing clostridia as indicators of past pollution.

Clostridium↗
PubMed1999

Blocked negative selection of developing T cells in mice expressing the baculovirus p35 caspase inhibitor.

Clonal deletion in the thymus by apoptosis is involved in purging the immune system of self-reactive T lymphocytes (negative selection). Cysteine proteases (caspases) belonging to the CPP32 family are activated during this process. We have produced transgenic mice expressing baculovirus p35, a broad-range caspase inhibitor. Thymocytes from p35 transgenic mice were resistant in vitro to several apoptosis-inducing agents; this resistance correlated with the inhibition of CPP32-like activity. Negative selection in vivo of thymocytes triggered by two exogenous antigens, staphylococcal enterotoxin B superantigen and an antigenic peptide in the F5 T-cell receptor transgenic model, was specifically inhibited in p35 transgenic mice. Our results provide direct evidence for caspase involvement in negative selection during thymocyte development.

Amino Acid Sequence↗
PubMed1988

Synthesis and binding affinity of an iodinated juvenile hormone.

The synthesis of the first iodinated juvenile hormone (JH) in enantiomerically enriched form is reported. This chiral compound, 12-iodo-JH I, has an iodine atom replacing a methyl group of the natural insect juvenile hormone, JH I, which is important in regulating morphogenesis and reproduction in the Lepidoptera. The unlabeled compound shows approximately 10% of the relative binding affinity for the larval hemolymph JH binding protein (JHBP) of Manduca sexta, which specifically binds natural 3H-10R,11S-JH I (labeled at 58 Ci/mmol) with a KD of 8 X 10(-8) M. It is also approximately one-tenth as biologically active as JH I in the black Manduca and epidermal commitment assays. The 12-hydroxy and 12-oxo compounds are poor competitors and are also biologically inactive. The radioiodinated [125I]12-iodo-JH I can be prepared in low yield at greater than 2500 Ci/mmol by nucleophilic displacement using no-carrier-added 125I-labeled sodium iodide in acetone; however, synthesis using sodium iodide carrier to give the approximately 50 Ci/mmol radioiodinated ligand proceeds in higher radiochemical yield with fewer by-products and provides a radioligand which is more readily handled in binding assays. The KD of [125I]12-iodo-JH I was determined for hemolymph JHBP of three insects: M. sexta, 795 nM; Galleria mellonella, 47 nM; Locusta migratoria, 77 nM. The selectivity of 12-iodo-JH I for the 32-kDa JHBP of M. sexta was demonstrated by direct autoradiography of a native polyacrylamide gel electrophoresis gel of larval hemolymph incubated with the radioiodinated ligand. Thus, the in vitro and in vivo activity of 12-iodo-JH I indicate that it can serve as an important new gamma-emitting probe in the search for JH receptor proteins in target tissues.

Animals↗
PubMedDate not supplied

[Myths about the prevention and control of non-communicable diseases in Latin America].

Given the increase of the burden of non-communicable diseases (NCD) and the possibility to avoid it, it is urgent to implement or strengthen NCD preventive programs in Latin America. However, many myths hinder the implementation of NCD programs. Myths on NCD include: a) NCD are degenerative and incurable; b) they are diseases of the elderly; c) they are diseases of the rich. Like wise there are myths about NCD preventive programs are: a) difficult to implement, b) expensive, and c) ineffective. We present data that demonstrate how these myths are untrue and discuss the challenges to find a balanced health policy that emphasizes the importance of NCD without overlooking other diseases.

Aging↗