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Biomedical subjects

R Saenz

Publications and source records attributed to R Saenz.

17 recordsLinked to original sources
PubMed1999

Regulation of expression of avirulence gene avrRxv and identification of a family of host interaction factors by sequence analysis of avrBsT.

Resistance in tomato line Hawaii 7998 as well as in several nonhost plants to Xanthomonas campestris pv. vesicatoria tomato strain (XcvT) is mediated in part by the avirulence gene avrRxv. Analysis of growth of wild-type and avrRxv deletion strains indicates that avrRxv plays a crucial role in the ability of XcvT 92-14 to induce resistance on Hawaii 7998. We used avrRxv reporter gene fusions and Northern (RNA) blot analysis to test several growth environments for inductive potential. We found that avrRxv is constitutively expressed at high levels and that growth in planta, in tobacco conditioned medium, and in hrp-inductive medium XVM2 did not affect the high levels of expression. In addition, hrp structural and regulatory mutant backgrounds had no effect. We mutated the bipartite plant inducible promoter (PIP)-box sequence and found that avrRxv activity appears to be independent of an intact PIP-box element. We present the sequence of the avrRxv homologue called avrBsT and align the six AvrRxv host interaction factor family members including mammalian pathogen virulence factors YopJ and YopP from Yersinia spp. and AvrA from Salmonella typhimurium, and open reading frame Y4LO with unknown function from the symbiont Rhizobium sp.

Amino Acid Sequence↗
PubMed1998

Portal and mesenteric vein thrombosis in a patient heterozygous for a mutation (Arg506-->Gln) in the factor V gen (factor V Leiden).

In 30-50% of patients with portal thrombosis, no underlying etiology is found. The recent reports of new hereditary clotting defects are contributing to the understanding of this problem, but they only justify a small number of idiopathic cases. Instead, anticoagulant protein C resistance, caused by a mutation in the V factor gene, appears to be at least 10 times more common than any of the other known inherited deficiencies of anticoagulant proteins. In spite of that, extensive thrombosis of portomesenteric or hepatic venous circulation has been rarely described in this hereditary clotting defect. We report a typical case of familial and recidivant deep vein thrombosis in a young man heterozygous for the factor V Leiden mutation (Arg506-Gln), who developed an acute portal and mesenteric vein thrombosis. The patient was discharged with an oral anticoagulant treatment and remains asymptomatic 2 years later. In conclusion, the high prevalence of the factor V Leiden in young and aged patients with idiopathic vein thrombosis and the case here described makes it obligatory to consider this disorder in patients with portal and/or mesenteric vein thrombosis, especially in those without evident etiology.

Adult↗
PubMed1996

Water and temperature relations and microconidial germination of Fusarium moniliforme and Fusarium proliferatum from maize.

The effects of water activity (aW, 0.994-0.85 = 0.4-21.0 (-)MPa water potential), temperature (5-42 degrees C), and their interactions on microconidial germination of three isolates each of Fusarium moniliforme and Fusarium proliferatum were determined in vitro on a maize meal extract medium. Temporal germination rates of microconidia of isolates of both species were significantly influenced by both aW and temperature. Germination was very rapid at > 0.94 aW with an almost linear increase with time. Germination rates of microconidia of F. moniliforme were slower than those of F. proliferatum isolates at marginal aW levels and 5-25 degrees C, while at higher temperature (30-37 degrees C), the former germinated more rapidly than the latter. The aW minima for germination of isolates of both species was 0.88, with none occurring at 0.85 aW over a 40-day incubation period. At 37 degrees C, isolates of F. moniliforme had slightly lower aW minima than those of F. proliferatum. The narrowest range of aW for germination was at 5 degrees C, and none occurred at 42 degrees C. The effect of aW x temperature interactions on the lag phases (h) prior to germination and the germination rates (h-1) were estimated using the Gompertz model and the Zwietering equation. This showed that lag phases were shorter at 25-30 degrees C and 0.994-0.98 aW, and were increased to 10-500 h at marginal temperatures (5-10 degrees C) for F. proliferatum and longer for F. moniliforme. At marginal aW levels (0.92-0.90), lag times were increased to > 250 h. Germination rates (h-1) were different for the two species. Microconidia of F. moniliforme germinated optimally at 25-37 degrees C and 0.96-0.98 aW, but this changed to 30 degrees C at 0.90-0.94 aW, while germination of microconidia of F. proliferatum remained optimum at 30 degrees C, regardless of aW. There were statistically significant (P < 0.01) effects of aW, temperature, isolate, and two- and three-way interactions for F. proliferatum, but there were no intraisolate effects for F. moniliforme. The ecological significance of these data for understanding colonization patterns of these important fumonisin-producing fungi are discussed.

Body Water↗
PubMed1994

In search of Asian war brides.

Because of the long presence of U.S. soldiers in Asia, war-bride marriages involving servicemen and Asian women have been formed throughout the century. The literature, however, contains little empirically sound information on Asian war brides. This analysis develops a methodology to identify war brides and applies it to estimate the number of war brides from the six major Asian groups, using the national 1980 Public Use Microdata Sample. Further analysis comparing Asian war brides with other groups of Asian wives tends to support the traditional and lower socioeconomic images commonly associated with Asian war brides.

Acculturation↗
PubMed1993

The human ecology of tornadoes.

This paper offers an empirical test of the impact of human ecological patterns and other known correlates on tornado occurrence. It uses the National Severe Storms Forecast Center's information on tornadoes from 1950 through 1990 and employs ecological data from the U.S. Bureau of the Census and the Environmental Protection Agency. The results show that metropolitan and other urban counties have higher odds of tornado occurrence than rural counties, and that the probability of occurrence of tornadoes increases with increases in the number of previous tornadoes. The paper assesses the meaning of this finding for demographers, atmospheric scientists, engineers, and disaster managers.

Disasters↗
PubMed1992

Chicano return migration to the Southwest: an integrated human capital approach.

"This study uses an integrated human capital framework to examine the relationship between human capital, employment and ethnic factors and return migration to the Southwest [United States] among Chicanos. The sample used in the study is derived from the 1980 Public Use Microdata Samples and contains 1,926 Chicano householders between the ages of 25 and 64 who were born in one of five southwest states, lived outside of this region in 1975, and worked in the civilian labor force at any time between 1975 and 1980. The results suggest that various human capital, employment and ethnic composition variables are important predictors of Chicano return migration."

Americas↗
PubMed1990

The effect of maquiladora employment on the monthly flow of Mexican undocumented immigration to the U.S., 1978-1982.

"Some controversy has surrounded the extent to which employment in maquiladoras (assembly plants located along the Mexican border) has stimulated undocumented immigration to the United States. This study uses monthly data of maquiladora employment and INS [Immigration and Naturalization Service] apprehensions in a 'push-pull' migration framework to study the association between these two variables during the April 1978 to January 1982 period. The findings suggest that there is a significantly negative relationship between the one month lag of maquiladora employment and INS apprehensions. Employment growth in the maquiladora sector tends to be followed by a reduction of apprehensions one month later. The study also finds that male and female apprehensions appear to respond to relatively similar economic factors."

Americas↗
PubMed1990

The problem posed by immigrants married abroad on intermarriage research: the case of Asian Americans.

"Cross-sectional and longitudinal variations in rates of intergroup marriage [in the United States] have often been used as indicators of assimilation for minority groups. This article demonstrates that both types of comparisons can give misleading results when census data are used for calculating intermarriage rates without restrictions. Census data include immigrants who married abroad (IMAs) in the enumeration. The inclusion of these individuals in the study of intermarriage inevitably biases the level of minority inmarriage upward, making cross-sectional and longitudinal comparisons of intermarriage rates for groups with different levels of IMAs inappropriate. Cumulation of IMAs also inflates the inmarriage rates of older cohorts, leading to a misimpression of increasing outmarriage among younger cohorts. These problems are illustrated for several Asian groups using 1980 Public Use Microdata Sample data for California. Alternative approaches for remedying the problem are proposed and their different implications for assimilation theory and research are discussed."

Acculturation↗
PubMed1989

Selectivity of Mexican American intraregional migration in the Southwest.

A significant amount of research in the last several decades has examined the migration of different racial groups such as whites and blacks in the US. Such studies have identified important demographic and socioeconomic predictors of migration. Mexican Americans represent 1 group that has largely been neglected in this respect. This study examines the relationship among demographic and socioeconomic variables and intraregional migration among Mexican Americans in 5 southwest states. Data from a subsample of 6137 householders included in the 1980 Public Use Microdata Sample are used for this purpose. The findings demonstrate that while some of the predictor variables are significantly related to migration, others are not. The results demonstrate the need for further research examining the extent to which previous findings on migration selectivity can be generalized to different racial and ethnic groups.

Americas↗
PubMed1988

Human immunodeficiency virus infection in the Republic of Panama.

Thirty-one documented acquired immune deficiency syndrome (AIDS) cases occurred in Panama during 1984-1987. Twenty-three (74%) patients were homosexual males and all but 2 patients recognized prior to June 1987 have died. To identify risk factors for human immunodeficiency virus infection, 287 male homosexual residents of Panama City were enrolled in a cross-sectional study. Nine had human immunodeficiency virus (HIV) antibody. Travel to the United States, homosexual relations with United States nationals in Panama, and sexual contacts in Panamanian clubs and bars were associated with human immunodeficiency virus infection by logistic regression analysis. Number of different male sex partners per year was identified but did not enter the logistic model at a significant level. To estimate seroprevalence in other high risk populations, 183 Panama City female prostitutes and 55 homosexual males from the rural Azuero peninsula were screened; none were seropositive. Eighty-four percent of Panamanian hemophiliacs had antibody; infection was related to factor VIII transfusions. Two of 182 sickle cell anemia patients and 15 of 7,720 volunteer blood donors were positive.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Studies on choline ad ethanolamine phosphoglyceride biosynthesis in developing rabbit brain.

Activities of cholinephosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) were evaluated in microsomal preparations derived from rabbit cerebrum. Animals ranged in age from nineteen days' gestation through two months of postnatal development. Under optimal conditions the properties of these transferases in rabbit brain were remarkably similar relative to pH, divalent cation requirements, and apparent-Km values for the CDP-intermediates and the lipid acceptor, respectively. Cholinephosphotransferase-specific activity exhibited a dramatic rise during the last 15%-20% of fetal life and a second rise to a maximum near the 15th postnatal day. Ethanolaminephosphotransferase-specific activity exhibited a similar, but less striking age-related increase during the same period. Growth of rabbit cerebrum as determined by weight, increased 30-fold during this same period (24 days gestation to the 19th postnatal day). Specific activities of these transferase were similar in brain preparations from mid-fetal and early adult rabbits. The maximum specific activity of cholinephosphotransferase exceeded that of ethanolaminephosphotransferase by 3-4-fold. Age-related changes in the specific activities of these transferases appear to correlate with the developmental pattern of morphological and compositional events occurring in rabbit cerebrum during the last third of gestation and the first three weeks of postnatal life.

Age Factors↗
PubMed1977

Edwardsiellosis in man and animals in Panamá: clinical and epidemiological characteristics.

Edwardsiella tarda was isolated during etiologic and epidemiologic investigations of diarrheal disease agents in man and for Enterobacteriaceae in various species of wild-caught animals in Panamá. A total of 50 strains were recovered from approximately 14,000 specimens cultured between 1965 and 1972. In this period, Edwardsiella was isolated from ten individuals with a clinically diagnosed diarrheal syndrome, while 20 of some 3,000 persons from rural areas were asymptomatic carriers of these organisms. Edwardsiella tarda was also associated with two fatal cases of extraintestinal infection in man. In both cases liver abscess was a predominant feature. Edwardsiella was not demonstrated in either symptomatic or asymptomatic persons from urban areas. Edwardsiella tarda was present among some of the wild fauna of Panamá; various species of animals including snakes, toads, monkeys, and opossums harbored this organism.

Animals↗
PubMedDate not supplied

Suicide and net migration in Texas counties, 1970 and 1980.

Recent research has examined the consequences of migration, with much of this work focusing on "boom" towns. This literature provides a useful framework for studying the consequences of population growth in other settings, however. The boom-town literature has generally used the social disruption hypothesis, which predicts social disruptions in communities growing rapidly through migration, to explain the results of migration in these communities. Suicide is one social disruption indicator which has not received much empirical attention. According to the social disruption hypothesis, a positive relationship is expected between the net migration and suicide rates. We examine this hypothesis using data from Texas nonmetropolitan counties for the last two decades. We also present separate analyses for metropolitan counties. The results fail to provide support for the hypothesis. There is generally no relationship between net migration and suicide rates in both nonmetropolitan and metropolitan counties. Alternative explanations fail to alter this finding.

Anomie↗
PubMedDate not supplied

Reliability of serum magnesium values during diabetic ketoacidosis in children.

OBJECTIVE: To determine the prevalence of hypomagnesemia in diabetic children during diabetic ketoacidosis and following restitution of acid-base balance. METHODS: Eight consecutive diabetic children, ranging in age from 8 to 16 years, hospitalized in the pediatric intensive care unit with diabetic ketoacidosis from October 1st. through December 31st, 1995. A control group of 33 metabolically stable diabetic children, and a control group of 30 healthy children. Both control groups were similar in composition regarding age and sex to the study group. None of the patients in the study group and none of the controls had Magnesium supplementation given to them during the study period. MEASUREMENTS: Total serum Magnesium concentrations were measured from peripheral venous blood in all 71 patients. For the study group serum Magnesium was determined in a serial fashion: 1. upon admission in diabetic ketoacidosis 2. 24 hours after admission 3. 72 hours after admission RESULTS: The prevalence of hypomagnesemia was 62.4% in patients with diabetic ketoacidosis, (Group 1), 25% in patients after partial correction of ketoacidosis, (Group 2), and none in patients after resolution of ketoacidosis, (Group 3). The prevalence of hypomagnesemia was 6% for the chronic, metabolically stable diabetic control group, (Group 4), but 0% for the non-diabetic control group, (Group 5). Average serum Magnesium levels were significantly lower (p less than 0.05), in patients admitted in diabetic ketoacidosis compared to those of both the diabetic and the non-diabetic control groups. Also average serum Magnesium levels were significantly lower (p less than 0.05), in patients with corrected diabetic ketoacidosis than those of the healthy control group. But there were no significant differences (p = 0.59263) in average serum Magnesium levels between the diabetic control group and the diabetic patients after resolution of ketoacidosis. CONCLUSIONS: In this study the prevalence of hypomagnesemia was documented to be higher than the average described elsewhere for pediatric, adult, and coronary intensive care units. As hypomagnesemia is an indication of Magnesium depletion, we speculate that the transient hypomagnesemia detected in our study group is an expression of a state of Magnesium depletion that is masked by correction of acidosis and the Magnesium shifts associated with it. Consequently serum Magnesium values ought to be considered most reliable during and not after correction of diabetic ketoacidosis. Since Magnesium was not supplemented to any of our patients, the normalization of their serum values must be the result of: a. decreased glycosuria-related urinary losses b. cessation of acidosis-related urinary losses c. Magnesium shifts from intra to extracellular space The high prevalence of hypomagnesemia and the significant lower average serum Magnesium levels in children with diabetic ketoacidosis reveals the magnitude of the problem and the potential for Magnesium depletion that occurs in diabetic children.

Adolescent↗