of equatorial spread-F (ESF) occurrence statistics into the IRI requires first a detailed charact... more of equatorial spread-F (ESF) occurrence statistics into the IRI requires first a detailed characterization, as a function of longitude, of the spatial and temporal distribution of the different types of ESF irregularity activity indices based on data from the different available techniques, ionosondes/digisondes, scintillation and satellite in-situ measurements. In this paper we present and discuss the distribution statistics of ESF events, mainly from ionograms, using the long term data sets available from equatorial and low latitude stations in Brazil and Argentina. Signi~~ant longitudinal dependence in the ESF occurrence is observed. The results are discussed on the basis of the Iongitude dependent magnetic declination angle that characterizes this region and on relevant thermospheric parameters. 01998 COSPAR. Published by Ekevier Science Ltd.
Trypanosoma cruzi presents six histones electrophoretically resolved in three gel systems. Indire... more Trypanosoma cruzi presents six histones electrophoretically resolved in three gel systems. Indirect evidence shows that one of these histones, name, corresponds to H4 in other species. We present evidence that histones is H4 by sequencing its amino terminal end. The amino terminal of T. cruzi histone H4, unlike that of other H4s examined thus far is not blocked. Moreover, this protein presents two variants. This partial amino acid sequence of T. cruzi histone H4 differs greatly from homologous sequences of human, yeast, or Tetrahymena.Since the conservatism of the core histones (H2A, H2B, H3, and H4) is clearly illustrated by comparative sequence analyses, the data shown here demonstrates that T. cruzi histone H4 is the most divergent reported. Quantitative analysis of the data suggests that the rate of substitutions in the histone H4 amino terminal sequence varies among different lineages. We postulate a slow-down in the evolutionary rate of histone H4 amino terminal domain in the metazoa branch related perhaps to the appearance of a novel function for this domain.
To describe the relationship of blood lead levels to menopause and bone lead levels, we conducted... more To describe the relationship of blood lead levels to menopause and bone lead levels, we conducted a cross-sectional study on 232 pre- or perimenopausal (PreM) and postmenopausal (PosM) women who participated in an osteoporosis-screening program in Mexico City during the first quarter of 1995. Information regarding reproductive characteristics and known risk factors for blood lead was obtained using a standard questionnaire by direct interview. The mean age of the population was 54.7 years (SD = 9.8), with a mean blood lead level of 9.2 microg/dL (SD = 4.7/dL) and a range from 2.1 to 32.1 microg/dL. After adjusting for age and bone lead levels, the mean blood lead level was 1.98 microg/dL higher in PosM women than in PreM women (p = 0.024). The increase in mean blood lead levels peaked during the second year of amenorrhea with a level (10.35 microg/dL) that was 3.51 microg/dL higher than that of PreM women. Other important predictors of blood lead levels were use of lead-glazed ceramics, schooling, trabecular bone lead, body mass index, time of living in Mexico City, and use of hormone replacement therapy. Bone density was not associated with blood lead levels. These results support the hypothesis that release of bone lead stores increases during menopause and constitutes an internal source of exposure possibly associated with health effects in women in menopause transition.
The purpose of this article is to report the increased incidence of community-acquired methicilli... more The purpose of this article is to report the increased incidence of community-acquired methicillin-resistant S. aureus in hand infections at an urban medical center. The authors performed a retrospective review of all patients with hand infections over a 21-month period, and all patients with culture-positive methicillin-resistant S. aureus were identified. Cases determined to be nosocomial were excluded. The study period was divided into three 7-month periods. A total of 343 hand infections were treated over a 21-month period. Eighty-nine patients (26 percent) with culture positive methicillin-resistant S. aureus were identified; of these, 75 were determined to be community-acquired methicillin-resistant S. aureus patients. Statistical analysis was performed using the Fisher's exact test (p < 0.0001), the chi-square test for equal proportions, the Cochran-Armitage trend test, and two-way analysis of variance. The demographics of the patients were compared using two-way analysis of variance, and patients were found to be similar in all three time periods with respect to mean age and sex. The incidence of community-acquired methicillin-resistant S. aureus increased to 40 percent during the last 7-month period compared with 14 percent during the first two periods. Overall, the incidence of methicillin-resistant S. aureus increased to 47 percent during the last 7 months compared with 16 percent and 17 percent in the first two 7-month periods, respectively. Based on their treatment approach and literature review, the authors have developed an algorithm to treat community-acquired methicillin-resistant S. aureus hand infections. The authors' findings at Temple University Hospital may help to alert health care providers to take necessary steps to control the spread of methicillin-resistant S. aureus in the community and in the inpatient setting. Cultures should be carefully followed and infections should be treated with appropriate antibiotics.
of equatorial spread-F (ESF) occurrence statistics into the IRI requires first a detailed charact... more of equatorial spread-F (ESF) occurrence statistics into the IRI requires first a detailed characterization, as a function of longitude, of the spatial and temporal distribution of the different types of ESF irregularity activity indices based on data from the different available techniques, ionosondes/digisondes, scintillation and satellite in-situ measurements. In this paper we present and discuss the distribution statistics of ESF events, mainly from ionograms, using the long term data sets available from equatorial and low latitude stations in Brazil and Argentina. Signi~~ant longitudinal dependence in the ESF occurrence is observed. The results are discussed on the basis of the Iongitude dependent magnetic declination angle that characterizes this region and on relevant thermospheric parameters. 01998 COSPAR. Published by Ekevier Science Ltd.
Trypanosoma cruzi presents six histones electrophoretically resolved in three gel systems. Indire... more Trypanosoma cruzi presents six histones electrophoretically resolved in three gel systems. Indirect evidence shows that one of these histones, name, corresponds to H4 in other species. We present evidence that histones is H4 by sequencing its amino terminal end. The amino terminal of T. cruzi histone H4, unlike that of other H4s examined thus far is not blocked. Moreover, this protein presents two variants. This partial amino acid sequence of T. cruzi histone H4 differs greatly from homologous sequences of human, yeast, or Tetrahymena.Since the conservatism of the core histones (H2A, H2B, H3, and H4) is clearly illustrated by comparative sequence analyses, the data shown here demonstrates that T. cruzi histone H4 is the most divergent reported. Quantitative analysis of the data suggests that the rate of substitutions in the histone H4 amino terminal sequence varies among different lineages. We postulate a slow-down in the evolutionary rate of histone H4 amino terminal domain in the metazoa branch related perhaps to the appearance of a novel function for this domain.
To describe the relationship of blood lead levels to menopause and bone lead levels, we conducted... more To describe the relationship of blood lead levels to menopause and bone lead levels, we conducted a cross-sectional study on 232 pre- or perimenopausal (PreM) and postmenopausal (PosM) women who participated in an osteoporosis-screening program in Mexico City during the first quarter of 1995. Information regarding reproductive characteristics and known risk factors for blood lead was obtained using a standard questionnaire by direct interview. The mean age of the population was 54.7 years (SD = 9.8), with a mean blood lead level of 9.2 microg/dL (SD = 4.7/dL) and a range from 2.1 to 32.1 microg/dL. After adjusting for age and bone lead levels, the mean blood lead level was 1.98 microg/dL higher in PosM women than in PreM women (p = 0.024). The increase in mean blood lead levels peaked during the second year of amenorrhea with a level (10.35 microg/dL) that was 3.51 microg/dL higher than that of PreM women. Other important predictors of blood lead levels were use of lead-glazed ceramics, schooling, trabecular bone lead, body mass index, time of living in Mexico City, and use of hormone replacement therapy. Bone density was not associated with blood lead levels. These results support the hypothesis that release of bone lead stores increases during menopause and constitutes an internal source of exposure possibly associated with health effects in women in menopause transition.
The purpose of this article is to report the increased incidence of community-acquired methicilli... more The purpose of this article is to report the increased incidence of community-acquired methicillin-resistant S. aureus in hand infections at an urban medical center. The authors performed a retrospective review of all patients with hand infections over a 21-month period, and all patients with culture-positive methicillin-resistant S. aureus were identified. Cases determined to be nosocomial were excluded. The study period was divided into three 7-month periods. A total of 343 hand infections were treated over a 21-month period. Eighty-nine patients (26 percent) with culture positive methicillin-resistant S. aureus were identified; of these, 75 were determined to be community-acquired methicillin-resistant S. aureus patients. Statistical analysis was performed using the Fisher's exact test (p < 0.0001), the chi-square test for equal proportions, the Cochran-Armitage trend test, and two-way analysis of variance. The demographics of the patients were compared using two-way analysis of variance, and patients were found to be similar in all three time periods with respect to mean age and sex. The incidence of community-acquired methicillin-resistant S. aureus increased to 40 percent during the last 7-month period compared with 14 percent during the first two periods. Overall, the incidence of methicillin-resistant S. aureus increased to 47 percent during the last 7 months compared with 16 percent and 17 percent in the first two 7-month periods, respectively. Based on their treatment approach and literature review, the authors have developed an algorithm to treat community-acquired methicillin-resistant S. aureus hand infections. The authors' findings at Temple University Hospital may help to alert health care providers to take necessary steps to control the spread of methicillin-resistant S. aureus in the community and in the inpatient setting. Cultures should be carefully followed and infections should be treated with appropriate antibiotics.
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Papers by Carlos Medina