Search PubMed⌕ Search

Biomedical subjects

J Sanchez

Publications and source records attributed to J Sanchez.

At least 73 records · Page 4Linked to original sources
PubMed1998

Primaquine prophylaxis against malaria in nonimmune Colombian soldiers: efficacy and toxicity. A randomized, double-blind, placebo-controlled trial.

BACKGROUND: Primaquine had a prophylactic efficacy of 90% to 95% against infection with Plasmodium falciparum and P. vivax in Indonesian settlers. OBJECTIVE: To evaluate the efficacy of primaquine prophylaxis for protecting nonimmune persons from malaria. DESIGN: Randomized, double-blind, placebo-controlled field study. SETTING: A malaria-endemic area in Colombia. PATIENTS: 176 healthy, young, nonimmune adult male soldiers. INTERVENTION: Primaquine, 30 mg/d, or matching placebo during 15 weeks of patrol in the endemic area and 1 week afterward. MEASUREMENTS: Symptomatic parasitemia was determined over the 16-week intervention period and for 3 weeks in base camp. RESULTS: Protective efficacy in the primaquine group (122 participants) was 89% (95% CI, 75% to 96%) against all types of malaria, 94% (CI, 78% to 99%) against P. falciparum malaria, and 85% (CI, 57% to 95%) against P. vivax malaria. Six primaquine recipients had mild to moderate gastrointestinal distress, and three had severe distress. CONCLUSIONS: For prophylaxis against P. falciparum malaria, primaquine has an efficacy and toxicity competitive with those of standard agents. A potential advantage of primaquine is that prophylaxis may be discontinued 1 week after the recipient has left the endemic area.

Adolescent↗
PubMed1998

Immunological detection of minimal residual disease in children with acute lymphoblastic leukaemia.

BACKGROUND: The clinical significance of submicroscopic levels of leukaemic cells in bone-marrow aspirates from children with acute lymphoblastic leukaemia (ALL) remains controversial. We prospectively determined the frequency and prognostic importance of minimal residual disease detected by a rapid immunological assay in bone-marrow aspirates of children with ALL. METHODS: 158 children with newly diagnosed ALL received 6 weeks of remission-induction chemotherapy. Once complete clinical remission was attained the patients received 2 weeks of consolidation therapy followed by continuation therapy. Bone-marrow aspirates were collected after induction therapy and during weeks 14, 32, and 56 of continuation therapy, and then at 120 weeks (end of therapy). Cells with leukaemia-associated immunophenotypes were investigated by multiparameter flowcytometry capable of detecting one leukaemic cell among 10,000 normal cells. FINDINGS: The proportion of patients with detectable leukaemic cells was 23% at remission induction and 17% at week 14 of continuation therapy, decreasing to 5% and 4% at weeks 32 and 56. None of the 65 samples examined at completion of therapy (week 120) showed evidence of disease. Detectable residual disease at the end of remission induction correlated with adverse genetic abnormalities--the Philadelphia chromosome and MLL gene rearrangements--but not with other presenting features. Detectable leukaemia was associated with subsequent relapse regardless of the time at which bone-marrow samples were examined (p < 0.002 for all comparisons). For example, 3-year cumulative incidence (SE) of relapse in patients with and without detectable leukaemia at remission induction was 32.5% (10.6) and 7.5% (4.0), respectively (p < 0.001); for tests done at week 14, it was 42.1% (14.6) and 6.6% (3.5), p < 0.001. These correlations remained significant after adjusting for adverse presenting features. A higher degree of marrow infiltration by leukaemic cells (> or = 0.1%) in week 14 samples identified a subset of patients with an especially poor prognosis. INTERPRETATION: Immunological detection of residual leukaemic cells at any point in the treatment course is a powerful predictor of relapse in children with ALL. Alternative treatment should be considered for cases with persistent disease beyond the first 3 months of continuation therapy.

Bone Marrow↗
PubMed1998

Studies of adsorption, activation, and inhibition of factor XII on immobilized heparin.

The aim of the present investigation was to clarify whether immobilized heparin does, as previously suggested, prevent triggering of the plasma contact activation system. Purified FXII in the absence or presence of antithrombin and/or C1 esterase inhibitor as well as plasma was exposed for 1 to 600 seconds to a surface modified by end-point immobilization of heparin. With purified reagents, a process including surface adsorption and activation of FXII occurred within 1 second. In the presence of antithrombin, the resulting surface-bound alpha-FXIIa was inhibited within that time. Likewise, the adsorption of native FXII from plasma was a rapid process. However, the inhibition of surface-bound alpha-FXIIa was slightly slower than with purified components. Nevertheless, neither beta-FXIIa nor FXIa were found in the plasma phase. Exposure of a surface prepared from heparin molecules, lacking antithrombin binding properties, to plasma resulted in surface-bound alpha-FXIIa within 1 second. In the liquid phase, beta-FXIIa was detected after 2.5 seconds and, 12 seconds later, FXIIa and FXIa in complex with the C1 esterase inhibitor appeared. Addition of heparin to plasma prior to surface exposure did not prevent activation of surface-bound FXII, nor did it increase the beta-FXIIa inhibition rate and prevent FXI activation in plasma, although beta-FXIIa and FXIa-AT complex formation occurred. It is concluded that surface-immobilized heparin, unlike heparin in solution, effectively inhibits the initial contact activation enzymes by an antithrombin-mediated mechanism, thereby suppressing the triggering of the intrinsic plasma coagulation pathway.

Adsorption↗
PubMed1998

Fishing, consumption, and risk perception in fisherfolk along an east coast estuary.

Increasingly public and governmental agencies are concerned about the safety of fish and shellfish that recreational fishermen consume. Fishing behavior, consumption patterns, and risk perceptions were examined for people flashing and crabbing in Barnegat Bay, NJ. Women fished in significantly larger groups than men, and their groups included more children. Subjects fished an average of seven times per month and crabbed three times per month; they caught fish on most outings, and 80% ate their catch. Subjects consumed fish an average of five times a month, eating just under 10 oz (ca. 280 g) per meal. Only 25% of the fish consumed by women, and 49% of the fish consumed by men, are self-caught. Nearly 90% of the people believe the fish and crabs from Barnegat Bay are safe to eat, although about 40% have heard some warnings about their safety. Most people heard about advisories from newspapers or television. Most subjects believe that saltwater fish are safer than freshwater fish and that fish they catch themselves or buy in a bay store are safer than those from a supermarket. People generally do not have a clear understanding of the relationship between contaminants and fish size or trophic level, suggesting an avenue for risk reduction.

Adolescent↗
PubMed1998

Fibrinogen and fibrinolysis in blood and in the arterial wall: its role in advanced atherosclerotic disease.

High plasma fibrinogen appears to be an important risk factor for the development of atherosclerosis. The aim of our study was to measure fibrinogen and fibrin degradation products (D-dimer), interleukin-6 tissue plasminogen activator, plasminogen activator inhibitor-1 and urokinase-type plasminogen activator in the plasma and arterial walls of 45 patients who had arterial surgery between April 1993 and November 1995. The arterial specimens were also examined by immunohistochemists for these same factors. The serum fibrinogen and fibrin degradation products were high in all patients, and fibrinolysis was depressed. Few leukocytes were seen in the arterial walls, which had poor fibrinolytic activity. Plasminogen-activator inhibitor activity in the wall was also reduced in the affected arterial walls. The abdominal aorta appeared to have the highest levels of fibrinogen and this may be related to its ability to form aneurysms. Fibrinogen may play an important role in the progression of atherosclerotic disease.

Aorta, Abdominal↗
PubMed1998

Sirenomelia sequence versus renal agenesis: prenatal differentiation with power Doppler ultrasound.

In order to assess the role of power Doppler ultrasound in the prenatal diagnosis of sirenomelia, prenatal findings in two fetuses with the sirenomelia sequence and in seven with bilateral renal agenesis were reviewed and compared. Both conditions were characterized by absence of renal vessels. However, the two common iliac arteries were always visualized in fetuses with renal agenesis, whereas absence of distal branching of the main abdominal vessel was a characteristic feature of sirenomelia. Power Doppler ultrasound allows expeditious identification of absent or non-functional renal arteries in fetuses with severe oligohydramnios. In addition, incorporation of power Doppler imaging to identify the aortic bifurcation could provide a diagnostic feature that could assist in the prenatal diagnosis of sirenomelia and in the differential diagnosis with other causes of bilateral renal agenesis.

Adult↗
PubMed1998

Morgagni's hernia resolved by laparoscopic surgery.

Morgagni's hernias represent between 2 and 4% of the whole of nontraumatic diaphragmatic hernias in the adult, and the treatment (even with minimal symptoms) is always with surgery. We present the case of a 50-year-old woman with an oppressive, postprandial discomfort in the right side of her thorax and with increased pain when supine. The x-ray examination indicated a large portion of transverse colon inside the thoracic cavity. Once the diagnosis of Morgagni's hernia had been obtained, she was scheduled for laparoscopic surgery to reduce the hernia and to reconstruct the defect of the diaphragm using a polypropylene mesh.

Female↗
PubMed1998

Carcinoid tumor of the thymus: a unique neoplasm of the mediastinum.

In this report, we describe a patient with a thymic carcinoid and the evolution of his disease for the past 5 years. Due to the distinct nature of thymic carcinoids, their unique biologic and endocrine properties, and the variety of available treatment options, it is important to differentiate this entity from other mediastinal tumors. The use of immunohistochemical studies or electron microscopy by the pathologist permits more accurate differentiation and diagnosis.

Carcinoid Tumor↗
PubMed1998

Neurobehavioral correlates of perceived mental and motor slowness in HIV infection and AIDS.

The authors assessed 72 human immunodeficiency virus (HIV)-infected patients with a self-rating slowness scale (SRSS) concerning mental and motor slowness in their activities of daily living. In order to understand the relationship between complaints of slowness and predictor variables, the investigators developed a preliminary model using multiple regression analysis. Reports of slowness on the SRSS were independently associated with self-reported cognitive and neurological symptoms and with peripheral neurological syndromes (e.g., neuropathy, myopathy). Lesser contributions to self-perceived mental and motor slowness were found for neuropsychological measures of information processing speed, severity of the infection, depression, HIV encephalopathy, and sociodemographic factors (e.g., age, education). The relationship among the predictor variables showed that complaints of slowness reflect neurological, psychiatric/psychological, and cognitive symptomatology of the HIV infection.

AIDS Dementia Complex↗
PubMed1998

Epidemiologic characterization of American cutaneous leishmaniasis in an endemic region of eastern Venezuela.

The status of American cutaneous leishmaniasis was investigated from 1985 to 1991 to provide an epidemiologic characterization of the disease in Bergantin, a rural community in the northeastern part of Anzoátegui State, Venezuela. The study revealed the presence of the infection during the period analyzed, with an average incidence of 50.2 cases per 10,000 inhabitants and this number has increased 1.5 times during the last two years. Three villages where clinical cases had been recorded were selected for a comparison of their prevalence data. These villages comprise the human population in the high and low altitude limits of Bergantin. Immunologic assessment of the inhabitants used two different antigen preparations to examine responses to parasites associated with the cutaneous and visceral forms of the disease. The leishmanin skin test (LST) was used in a sample of 276 individuals (46.3% of the inhabitants) and resulted in an overall positivity of 16.7%. The percentage of LST positivity varied with age and sex, yet analysis of this response and the prevalence for each village reflected the specific characteristics of these localities. La Montaña, situated at 800 meters above sea level, had the highest prevalence (800 cases per 10,000 inhabitants) and the most positive LST response (21.2%) in comparison with the two other villages situated at a lower altitude (300 meters above sea level).

Endemic Diseases↗
PubMed1998

Fetal prognosis in varix of the intrafetal umbilical vein.

To assess the clinical significance of varix of the intraabdominal portion of the umbilical vein, we reviewed 10 cases diagnosed prenatally by ultrasonography at a median gestational age of 27 weeks. A comprehensive anatomic survey and serial follow-up scans were performed in each case. All three fetuses with associated anomalies died in utero, and prenatal karyotyping revealed that two of them had a chromosomal abnormality. In six of the seven cases with structurally normal fetuses the pregnancy proceeded uneventfully, and no neonatal complications were attributed to the umbilical vein varix. Our experience and the review of the literature revealed 42 cases with information on fetal outcome. Overall, 24% of the fetuses died, 12% had a chromosomal abnormality, and 5% developed hydrops. We conclude that fetuses with varix of the intrafetal umbilical vein should be considered at risk for poor outcome. However, if no other anomalies are present, the prognosis is generally good.

Female↗
PubMed1998

Lack of normal MR enhancement of the pituitary gland: findings in three siblings with combined pituitary hormone deficiency.

We present the MR appearance of the sella turcica in three sibling dwarfs with combined pituitary hormone deficiency in which MR images revealed a peripheral curvilinear band of enhancement about the pituitary gland in all three patients, a normal-size pituitary gland in two siblings, a mildly enlarged pituitary gland in one sibling, and a thin infundibulum and a normal posterior pituitary bright spot in all three siblings. Possible antecedents include an abnormal vascular supply, pituitary gland replacement by a nonfunctioning adenoma, a proteinaceous cyst, or a hamartoma.

Adolescent↗
PubMed1997

Probability of carrying a mutation of breast-ovarian cancer gene BRCA1 based on family history.

BACKGROUND: Heritable mutations of the breast cancer gene BRCA1 are rare, occurring in fewer than 1% of women in the general population, and therefore account for a small proportion of cases of breast and ovarian cancers. Nevertheless, the presence of such mutations is highly predictive of the development of these cancers. PURPOSE: We developed and applied a mathematic model for calculating the probability that a woman with a family history of breast and/or ovarian cancer carries a mutation of BRCA1. METHODS AND RESULTS: As a basis for the model, we use Mendelian genetics and apply Bayes' theorem to information on the family history of these diseases. Of importance are the exact relationships of all family members, including both affected and unaffected members, and ages at diagnosis of the affected members and current ages of the unaffected members. We used available estimates of BRCA1 mutation frequencies in the general population and age-specific incidence rates of breast and ovarian cancers in carriers and noncarriers of mutations to estimate the probability that a particular member of the family carries a mutation. This probability is based on cancer statuses of all first- and second-degree relatives. We first describe the model by considering single individuals: a woman diagnosed with breast and/or ovarian cancer and also a woman free of cancer. We next considered two artificial and two actual family histories and addressed the sensitivity of our calculations to various assumptions. Particular relationships of family members with and without cancer can have a substantial impact on the probability of carrying a susceptibility gene. Ages at diagnosis of affected family members and their types of cancer are also important. A woman with two primary cancers can have a probability of carrying a mutation in excess of 80%, even with no other information about family history. The number and relationships of unaffected members, along with their current ages or ages at death, are critical determinants of one's carrier probability. An affected woman with several cancers in her family can have a probability of carrying a mutation that ranges from close to 100% to less than 5%. CONCLUSION: Our model gives informative and specific probabilities that a particular woman carries a mutation. IMPLICATIONS: This model focuses on mutations in BRCA1 and assumes that all other breast cancer is sporadic. With the cloning of BRCA2, we now know that this assumption is incorrect. We have adjusted the model to include BRCA2, but the use of this version must await publication of penetrance data for BRCA2, including those for male breast cancer that are apparently associated with BRCA2 but not with BRCA1. The current model is, nevertheless, appropriate and useful. Of principal importance is its potential and that of improved versions for aiding women and their health care providers in assessing the need for genetic testing.

Adult↗
PubMed1997

Engineering of cholera toxin A-subunit for carriage of epitopes at its amino end.

The cholera toxin A-subunit (CTA) was genetically engineered at its amino end and tested for carriage of epitopes by fusion of the STa heat-stable enterotoxin analogue CAELCCNPAC. Efficient holotoxin formation by complementation in trans with cholera toxin B-subunit (CTB) indicated no decrease in affinity for CTB but evidence of reduced toxicity suggests steric interference by the decapeptide with the active site. The holotoxin was stable, able to bind to GM1 and was recognized by anti-STa and anti-CTA antibodies. The use of a full-length CTA might have been a key step for successful genetic fusions. Based on these findings, it seems worthwhile pursue the development of CTA for construction of recombinant mucosal immunoadjuvants.

Amino Acid Sequence↗
PubMed1997

High-frequency FSH and LH pulses in obese menopausal women.

We studied the pulsatile luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretory patterns, at early or intermediate years of menopause in seven normal women with different degrees of obesity, taking blood samples every minute for 40 min to 2 h. The hormones were assayed with an immunoradiometric assay (IRMA) system, analyzing with the cluster pulse algorithm. All women showed hormone pulses every 8-10 min. In five of them were found periods of discrete pulses with oscillations of high amplitude alternating with periods of pulses of low amplitude. In two cases, the high-frequency oscillatory pattern with low amplitude was found around low mean levels of 22.8 and 25.7 IU/L. The LH oscillatory pattern also had a high frequency, but at a lower level, giving a high FSH/LH ratio. The coincidence index of FSH with LH peaks was 76.6%. We concluded that at menopause, the frequency of FSH and LH secretion increases with a high FSH/LH ratio. Obese menopausal women may have the same high-frequency oscillatory patterns, but at low levels.

Body Mass Index↗