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PubMed2005

Clestobothrium gibsoni n. sp. (Cestoda: Bothriocephalidae) from the bullseye grenadier Bathygadus macrops Goode & Bean (Macrouridae) in the Gulf of Mexico.

Clestobothrium gibsoni n. sp. is described from the intestine of the bullseye grenadier Bathygadus macrops (Macrouridae) collected in the northeastern Gulf of Mexico. The new species can be distinguished from both C. crassiceps (Rudolphi, 1819), the type-species of the genus, and C. neglectum (Lönnberg, 1893), the second species in the genus, by its unique ovary, which is transversely elongate and tapered on both ends rather than being U-or H-shaped, and by having more testes (60-65 vs 40-50 and 35-45 per proglottid). The new species is also compared to Bothriocephalus acheilognathi Yamaguti, 1934 and B. kivuensis Baer & Fain, 1954, two species with similar scoleces which have previously been assigned to Clestobothrium . The generic diagnosis of Clestobothrium is amended to include species with either anoperculate or operculate eggs. This is the first report of an adult tapeworm from a species of Bathygadus , and the first report of a species of Clestobothrium Lühe, 1899 (Bothriocephalidae) from the Gulf of Mexico.

Animals↗
PubMed1988

Chagas disease in Mexico.

Mexico - the northernmost country of Latin America - has long been thought to have an unusually low prevalence of Chagas disease compared with other Latin American countries. This has seemed unusual because of the large number of vector species and subspecies reported from the country, and the social and ecological conditions that seem to parallel those in other countries where Chagas disease is recognized as a major public health priority. This review seeks to clarify the question, and suggests that the epidemiological, parasitological, and entomological pattern of Chagas disease in Mexico may also parallel that of other endemic regions, but has been masked by poor awareness of the disease both at local and institutional levels.

Journal Article↗
PubMed1988

Neurocysticercosis in Mexico.

Cysticercosis is caused by the establishment of Taenia solium larvae (cysticerci), mainly in the central nervous system (CNS) and skeletal muscle of humans and pigs, after ingestion of eggs shed in human faeces by the adult tapeworm (see centrepage diagram). Human neurocysticercosis - often a life-threatening disease - is increasingly recognized as a public health problem, especially in developing countries. Clinical incidence of neurocysticercosis can reach 7% in Mexico and 18% in the Ekari population of New Guinea, while prevalence in autopsies ranges from 0.4% to 3.6% in several countries of Latin America, Asia and Africa. Many cases have also been recently reported in the USA, usually in immigrants. In this review, Ana Flisser focuses on the problems of cysticercosis in Mexico, where the disease is now recognized as a priority both in public health and economic terms. Recognition of the problem has been greatly aided in recent years by new developments in diagnosis - especially computed tomography (CT) to diagnose early stages of neurocysticercosis - and by improved drug treatment.

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PubMed1990

The Valley of Mexico: summary of observational studies on its air quality and effects on vegetation.

Present day Mexico City was established on the banks of the now dead Lake Texcoco by Aztec Indians in a.d. 1325. Over time, increasing population growth, urbanization, vehicular traffic and the number of diverse stationary sources, coupled with its topography and the resultant frequency of prevalent stagnant air masses make Mexico City one of the most polluted areas in the world. Use of biological indicator plants since the early 1970s has shown the critical nature of phytotoxic photochemical oxidants in the region. More recent empirical studies with bean, soybean and pine species confirm these observations and raise concern regarding the geographic magnitude of the problem. Surface measurements of air quality in the region are inadequate and require much additional support. Ultimately, ambient air quality measurements must be coupled with the observations on responses of sensitive vegetation. While the results presented in this paper are primarily observational or qualitative, they hopefully serve the purpose of bringing attention to a critical air quality issue in a developing country.

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PubMed1994

Polynuclear aromatic hydrocarbon contaminants in oysters from the Gulf of Mexico (1986-1990).

Polynuclear aromatic hydrocarbon (PAH) contaminant concentrations in 870 composite oyster samples from coastal and estuarine areas of the Gulf of Mexico analyzed as part of National Oceanographic and Atmospheric Administration's (NOAA's) National Status and Trends (NS&T) Mussel Watch Program exhibit a log-normal distribution. There are two major populations in the data. The cumulative frequency function was used to deconvolute the data distribution into two probability density functions and calculate summary statistics for each population. The first population consists of sites with lower PAH concentration probably due to background contamination (i.e. stormwater runoff, atmospheric deposition). The second population are sites with higher concentrations of PAHs associated with local point sources of PAH input (i.e. small oil spills, etc.). The temporal pattern for the mean concentration of the populations from the Gulf of Mexico is consistent with large-scale climatic factors such as the El Niño cycles which affect the precipitation regime.

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PubMed1996

Evaluation of an antigen capture ELISA based on recombinant mexico virus capsid protein.

BACKGROUND: The diagnosis of gastrointestinal infections caused by small round structured viruses (SRSV) has relied upon electron microscopy and antigen/antibody assays based on Norwalk virus. We investigated cases of gastroenteritis associated with SRSVs employing a new sandwich enzyme-linked immunosorbent assay (ELISA) using hyperimmune animal anti-sera against recombinant Mexico virus capsid protein (rMXV). STUDY DESIGN: One hundred and thirty-five specimens from 86 episodes of gastroenteritis associated with SRSVs, collected in the UK between October 1993 and September 1994, were tested in the rMXV assay. RESULTS: Forty-seven (35%) specimens from 35 of 86 (41%) episodes were positive in the rMXV ELISA and these could further be divided into high and low reactors. Sequencing of a 266-base region of the RNA polymerase gene revealed that strains highly reactive in the rMXV assay demonstrated a high degree of similarity to MXV (97-99% at the nucleotide level), whereas low-reactive strains consist of Mexico-like strains and a heterogeneous group of viruses exhibiting 70-75% similarity to MXV. CONCLUSION: Our results indicate that the rMXV ELISA is predominantly a type specific assay, although some cross reactivity with other genogroup 2 SRSVs was observed. MXV was responsible for 26% of SRSV-associated gastrointestinal infections investigated in the UK during one year's surveillance.

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PubMedDate not supplied

The importance of quality of care in perinatal mortality: a case-control study in Chiapas, Mexico.

BACKGROUND: This study was undertaken in order to ascertain the relative importance of different risk factors for perinatal mortality (PM) in a community of Chiapas, Mexico stressing the importance of antenatal and neonatal medical care. METHODS: Cases were stillbirth and early neonatal death (END). Two children born in the same hospital and/or day as the case were randomly selected as controls, in Tapachula, Chiapas, Mexico. Socioeconomic, cultural, maternal, pregnancy, delivery, product and medical care factors were recorded. Two analyses were performed using multiple logistic regression: one for stillbirths, the other for END. RESULTS: PM rate was 46.7/1000; 142 cases and 284 controls were studied. Fifteen cases were excluded due to congenital malformations; 62 stillbirth and 65 END were analyzed. For stillbirth, pregnancy-delivery and maternal medical care factors resulted in the most strongly associated risk factors for PM (OR=27.5 95% CI 6.4-116.8), and within this index insufficient prenatal care had the strongest impact on PM (%population attributable risk (%PAR)=24%). For END, fetal conditions and the newborn medical care index had the strongest association with PM (OR=9.5 95% CI 1.5-60.3), and within the index inappropriate medical care of the newborn (%PAR=27%) was the most important variable. CONCLUSIONS: Our results support the fact that insufficient prenatal care and failure to comply with the standards of care for labor, delivery and for the care of the newborn are strong predictors of PM.

Adolescent↗
PubMed2001

Seasonal variation of macro and trace mineral contents in 14 browse species that grow in northeastern Mexico.

Leaves and twigs from shrub species consumed by range goats: Acacia berlandieri, Acacia farnesiana, Acacia greggii, Acacia rigidula, Celtis pallida, Cercidium macrum, Condalia obovata, Cordia boissieri, Desmanthus virgathus, Leucaena leucocephala, Leucophyllum texanum, Opuntia lindehimieri, Porlieria angustifolia, Prosopis glandulosa, and Ziziphus obtusifolia were evaluated for comparative seasonal contents of Ca, P, Mg K, Zn, Mn, Cu and Fe. Plants were collected in summer (September 12, 1992), fall (November 20, 1992), winter (February 20, 1993) and spring (May 22, 1993) in Marín, County, Nuevo Leon, Mexico. During spring and summer mineral concentrations were higher in general. Only Ca, Mg, K, and Fe were in substantial amounts in all seasons to meet adult goat requirements. With the exception of spring, shrubs had extremely low P concentrations. Manganese, Cu and Zn in most plants had low marginal levels to meet adult goat requirements. Moreover, potential intake of P, Mn, Cu and Zn in shrub species by goats weighing 50kg BW consuming 2.0kg per day DM was low. However, plants such as D. virgathus, L. texanum, P. glandulosa, L. leucocephala and C. macrum can be considered prominent components in diets of range goats because of their high mineral concentrations. It appears that ration formulations for range goats in northeastern Mexico should include P, Mn, Cu and Zn in all seasons of the year.

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PubMed2001

A modified stepping-stone model of population structure in red drum, Sciaenops ocellatus (Sciaenidae), from the northern Gulf of Mexico.

Genetic studies of population or 'stock' structure in exploited marine fishes typically are designed to determine whether geographic boundaries useful for conservation and management planning are identifiable. Implicit in many such studies is the notion that subpopulations or stocks, if they exist, have fixed territories with little or no gene exchange between them. Herein, we review our long-term genetic studies of red drum (Sciaenops ocellatus), an estuarine-dependent sciaenid fish in the Gulf of Mexico and western Atlantic Ocean. Significant differences in frequencies of mitochondrial DNA haplotypes and of alleles at nuclear-encoded microsatellites occur among red drum sampled across the northern Gulf of Mexico. The spatial distribution of the genetic variation, however, follows a pattern of isolation-by-distance consistent with the hypothesis that gene flow occurs among subpopulations and is an inverse (and continuous) function of geographic distance. However, successful reproduction and recruitment of red drum depend on estuarine habitats that have geographically discrete boundaries. We hypothesize that population structure in red drum follows a modified one-dimensional, linear stepping-stone model where gene exchange occurs primarily (but not exclusively) between adjacent bays and estuaries distributed linearly along the coastline. Gene flow does occur among estuaries that are not adjacent but probabilities of gene exchange decrease as a function of geographic distance. Implications of our hypothesis are discussed in terms of inferences drawn from patterns of isolation-by-distance and relative to conservation and management of estuarine-dependent species like red drum. Based on estimates of the ratio of genetic effective population size and census size in red drum, observed patterns of gene flow in red drum may play a significant role in recruitment.

Animals↗
PubMed2000

Effect of stream channel size on the delivery of nitrogen to the Gulf of Mexico

An increase in the flux of nitrogen from the Mississippi river during the latter half of the twentieth century has caused eutrophication and chronic seasonal hypoxia in the shallow waters of the Louisiana shelf in the northern Gulf of Mexico. This has led to reductions in species diversity, mortality of benthic communities and stress in fishery resources. There is evidence for a predominantly anthropogenic origin of the increased nitrogen flux, but the location of the most significant sources in the Mississippi basin responsible for the delivery of nitrogen to the Gulf of Mexico have not been clearly identified, because the parameters influencing nitrogen-loss rates in rivers are not well known. Here we present an analysis of data from 374 US monitor ing stations, including 123 along the six largest tributaries to the Mississippi, that shows a rapid decline in the average first-order rate of nitrogen loss with channel size--from 0.45 day (-1) in small streams to 0.005 day (-1) in the Mississippi river. Using stream depth as an explanatory variable, our estimates of nitrogen-loss rates agreed with values from earlier studies. We conclude that the proximity of sources to large streams and rivers is an important determinant of nitrogen delivery to the estuary in the Mississippi basin, and possibly also in other large river basins.

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PubMed1998

Natal origins of migratory monarch butterflies at wintering colonies in Mexico: new isotopic evidence.

Each year, millions of monarch butterflies from eastern North America migrate to overwinter in 10-13 discrete colonies located in the Oyamel forests of central Mexico. For decades efforts to track monarch migration have relied on observations and tag-recapture methods, culminating with the discovery of the wintering colonies in 1975. Monarch tag returns from Mexico, however, are few and primarily from two accessible colonies, and therefore tag-recapture techniques have not quantified natal origins or distinctiveness among monarch populations at wintering sites. Such information would be invaluable in the conservation of the monarch and its migration phenomenon since the wintering sites currently are threatened by habitat alteration. Here we show that stable hydrogen (deltaD) and carbon (delta13C) isotope ratios of wintering monarchs can be used to evaluate natal origins on the summer breeding range. Stable-hydrogen and carbon isotopic values of 597 wintering monarchs from 13 wintering roost sites were compared with isotopic patterns measured in individuals at natal sites across their breeding range over a single migration cycle. We determined that all monarch wintering colonies were composed of individuals originating mainly from the Midwest, United States, thereby providing evidence for a panmictic model of wintering colony composition. However, two colonies showed more northerly origins, suggesting possible priority colonies for conservation efforts.

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PubMed1975

The 1971 red tide and its impact on certain reef communities in the mid-eastern Gulf of Mexico.

Effects of the 1971 spring-summer red tide upon mid-eastern Gulf of Mexico patch reef communities are discussed. In situ (SCUBA) observations at widely scattered reef localities between 13-30 m off Sarasota, Florida, both before and after the red tide support the following: 1) under the appropriate environmental conditions, red tides may result in near-complete extirpations of shallow-water (less than 40 m) reef biotas from extensive areas on the inner central-West Florida Shelf), 2) recolonization by certain biotic groups is relatively rapid (e.g., benthic algae and fishes) while that of others (e.g., alcyonarian corals, scleractinian corals, and echinoderms) is slow and may require several years, and 3) seasonal progression as well as true ecological succession following certain red tides may temporarily result in floral and faunal assemblages qualitatively and quantitatively distinctive from those prior to the red tide. It is therefore suggested that certain red tides, particularly those generated beneath pronounced thermoclines, may be previously underestimated phenomena regulating the composition, abundance, and distribution of shallow-water reef biotas in the mid-eastern Gulf of Mexico. It is surmised that the periodic occurrence of these red tides may prevent the evolution of a climax or equilibrium reef community.

Animals↗
PubMed2000

Leaves of Salicaceae (Salix and Populus) from Oligocene Sediments Near Tepexi de Rodríguez, Puebla, Mexico.

Eleven new salicaceous taxa based on fossil leaves, seven Salix and four Populus species, are described from the Oligocene Los Ahuehuetes locality, Pie de Vaca Formation, near Tepexi de Rodríguez in Puebla, Mexico. They are characterized by the presence of typical salicoid teeth, camptodromous secondary venation, and elliptic or lanceolate shape. Morphological differences between these new fossil plants and those reported previously from the United States and elsewhere indicate that diversification among these taxa occurred early during their differentiation. Furthermore, the limited morphological similarities of the fossil and extant plants growing naturally in Mexico also indicate a high rate of evolution. Documenting the expansion of high-latitude North American taxa into lower latitudes at the time of deposition of the Pie de Vaca Formation confirms that at least some of the typical boreal taxa were part of dry tropical communities in low-latitude North America and underscores the need to reevaluate the origin of this southern vegetation.

Journal Article↗
PubMed2000

Reconstruction of the Leaves of Two New Species of Pseudosmodingium (Anacardiaceae) from Oligocene Strata of Puebla, Mexico.

Leaves of two new plants are reconstructed from their isolated leaflets collected from the Oligocene Los Ahuehuetes locality near Tepexi de Rodríguez in Puebla, Mexico. The leaves of Pseudosmodingium mirandae Ramírez-Garduño et al. are compound imparipinnate with leaflets of variable morphology. The leaflets of five leaf morphotypes vary from narrow elliptic to lanceolate or lorate; they are symmetrical to slightly asymmetrical, with acute to attenuate apex, acute to cuneate base, and entire to serrate margin. Venation is simple pinnate craspedodromous, with secondary veins slightly curved near their base; secondary veins may dichotomize near the margin to become tertiary veins, and intersecondary veins are small and oblique to the secondary veins. A small number of leaflets assigned to Pseudosmodingium terrazasiae Ramírez-Garduño et al. are distinguished from P. mirandae by the leaflet shape, length&rcolon;width ratio, base shape, and apex angle. Morphological comparison of the fossil leaves with leaves of extant species of Anacardiaceae based on numerical analyses indicates a close similarity between P. mirandae and Pseudosmodingium multifolium Rose, while P. terrazasiae is more similar to Pseudosmodingium perniciosum (HBK) Engl. The presence of fossil species with extant relatives that are endemic to Mexico, along with previous reports, indicates that by the Oligocene, some lineages were already in place, although today they form part of the more xeric communities in southern North America.

Journal Article↗
PubMed1998

Reproductive risk factors for breast cancer in Hispanic and non-Hispanic white women: the New Mexico Women's Health Study.

The authors conducted a population-based case-control study of breast cancer in Hispanic women in New Mexico. Hispanic and non-Hispanic white women with incident breast cancer, aged 30-74 years and diagnosed between 1992 and 1994, were identified by the New Mexico Tumor Registry. Controls were selected using random digit dialing and frequency matched by ethnicity, age, and region. Information on reproductive history, lactation, and other risk factors was collected through in-person interviews; 719 Hispanics and 836 non-Hispanic whites were included in the analysis. Conditional logistic regression was used to estimate relative risk of breast cancer for reproductive factors and to assess ethnic differences in effects. Older age at first full-term birth was associated with breast cancer among Hispanics; the odds ratio for women aged 27 years and older at first full-term birth compared with women 18 years or younger was 2.26 (95% confidence interval 1.17-4.38) compared with 1.60 (95% confidence interval 0.86-3.01) for non-Hispanic whites. Higher parity was associated with reduced risk of breast cancer for non-Hispanic whites, but not Hispanics (p < 0.008). Longer lactation was associated with reduced risk in premenopausal Hispanic women and premenopausal and postmenopausal non-Hispanic white women. Reproductive factors explained 17% of the ethnic difference in breast cancer incidence for postmenopausal women and none of the difference for premenopausal women.

Adult↗
PubMed1996

An aflatoxin-associated mutational hotspot at codon 249 in the p53 tumor suppressor gene occurs in hepatocellular carcinomas from Mexico.

The p53 tumor suppressor gene is commonly mutated in human hepatocellular carcinoma (HCC). The most frequent mutation in HCC in populations exposed to a high dietary intake of aflatoxin B1 (AFB1) is an AGGarg-->AGTser missense mutation in codon 249 of the p53 gene. We analyzed HCCs from Monterrey, Mexico, for the codon 249ser hotspot mutation. We also analyzed the serum AFB1-albumin adduct levels of the donors and family members to measure the current AFB1 exposure in this population. Moreover, the presence of hepatitis B and/or C viral infection (HBV or HCV) was analyzed serologically in the patients. Tumor cells were microdissected from tissue sections and exon 7 p53 sequences were amplified by polymerase chain reaction from genomic DNA and sequenced directly. The serological tests for anti-p53 antibodies, HBV or HCV were done by ELISA. Immunohistochemical analysis of p53 protein was done using a polyclonal rabbit antiserum (CM-1). Eight of 21 cases were positive by p53 immunohistochemistry. Of the 16 cases sequenced for exon 7 of p53 three codon 249 AGGarg-->AGTser mutations were found. Serum antibodies recognizing p53 protein were found in one of 18 patients. Positive serology for HBV and/or HCV was found in 12 of 20 cases. The serum AFB1-albumin adduct levels in this population ranged from 0.54 to 4.64 pmol aflatoxin/mg albumin. These results indicate that dietary AFB1 and hepatitis viruses are etiological agents in the molecular pathogenesis of HCC in this geographic region of Mexico.

Adult↗
PubMedDate not supplied

Tandem repeat sequence variation and length heteroplasmy in the mitochondrial DNA D-loop of the threatened Gulf of Mexico sturgeon, Acipenser oxyrhynchus desotoi.

Genetic variability within the Suwannee River, Florida, population of Gulf of Mexico sturgeon, Acipenser oxyrhynchus desotoi, was assessed by examining sequence and length variation within the control region, or D-loop, of the mitochondrial genome. Although once abundant throughout the Gulf of Mexico, Gulf sturgeon are now listed as a threatened species by the U.S. Fish and Wildlife Service. Mitochondrial DNA was analyzed for length variation from 168 individual Gulf sturgeon by PCR amplification and visualization of PCR products using ethidium bromide-stained agarose gels. Of the 168 individual Gulf sturgeon, 31 (18.5%) were heteroplasmic for one to four copies of an 81-base pair, tandemly repeated sequence in the D-loop region. However, no individuals homoplasmic for multiple copies of the repeat sequence were observed. The existence and nature of these tandem repeats in heteroplasmic individuals was confirmed by direct sequencing of the PCR products for a subset of 22 individuals. The results are consistent with the apparent nature and mechanism of heteroplasmy observed in a congeneric species, A. transmontanus. In addition, sequences for 187 base pairs outside of the tandem repeats were identical among all 16 individuals assayed for this region. Lack of variable sequences is concordant with earlier studies involving mtDNA restriction fragment length profiles of Gulf sturgeon found in the Suwannee River. The absence of sequence variation exclusive of the tandem repeats is consistent with the hypothesis that the subspecies has undergone a population or evolutionary bottleneck.

Animals↗
PubMed2001

SLE in a United States-Mexico border community.

This report describes the results of a clinic-based study conducted to verify a community-reported excess prevalence of systemic lupus erythematosus (SLE) and a possible connection between ethnicity and environmental factors in the reporting of SLE in the United States-Mexico border town of Nogales, Arizona. A community group in Nogales reported 37 cases of SLE in its community, suggesting a prevalence rate of 200 per 100,000. This report describes 19 definite and 7 probable cases of SLE using the 1982 American College of Rheumatology criteria. All definite and probable cases were self-identified, Mexican-American females. This yields a prevalence rate of 94 per 100,000, among the highest reported to date. The majority of cases resided within 3 miles of the United States-Mexico border and within 1 mile of the polluted Nogales Wash or ground wells with documented toxins. It remains to be determined whether this confirms that SLE is more common in Mexican-Americans or whether environmental factors, especially pollutants, are predominantly responsible. In addition to the need to be aware about the apparent increased risk of SLE in many Latin-Americans, clinicians should ask about possible environmental factors.

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