Hepatitis B and C among adolescents at an STD clinic on the US-Mexico border.

Risky sexual behavior and drug use are factors associated with acquisition of hepatitis B and C. This cross-sectional study investigated hepatitis B and C among 296 adolescents at a sexually transmitted disease clinic in El Paso, Texas, between April 1, 1997, and February 1, 1998. Questionnaires, medical record abstraction, and serum antibody tests provided data on demographics, risk factors, and seroprevalence status. Only 15% of participants always used condoms, 23% had a previous sexually transmitted disease, 46% had more than 1 sexual partner in the last 6 months, and 7% used intravenous drugs. Results showed low seroprevalence of hepatitis B (4.1%) and hepatitis C (3.1%). No significant risk factors were associated with hepatitis B seroprevalence. In contrast, male gender, speaking Spanish, not attending school, having more than 1 sexual partner, and injection drug use were all associated with hepatitis C. Hepatitis B and C seroprevalence rates among high-risk adolescents are lower in El Paso than in other similar US populations, presenting an ideal climate for prevention programs.

Improving hepatitis B immunization among high-risk adolescents: a low-cost intervention on the Mexico-United States border.

OBJECTIVE: To analyze factors associated with hepatitis B immunization adherence among adolescents attending a sexually transmitted disease (STD) clinic in El Paso, a city in Texas that is on the border between Mexico and the United States of America. METHODS: In this cohort study with 248 adolescents we obtained data on demographics and health beliefs through personal interviews and medical record abstraction. We monitored each of the individuals for 8 months to determine whether the adolescents received a first, second, and third dose of the hepatitis B vaccine. RESULTS: Overall, 32% of the adolescents received the first immunization, 9% the second, and 2% the third. The strongest predictor of receiving either one or two doses was providing the vaccine at the STD clinic as opposed to referring adolescents to a separate vaccination clinic (relative risk (RR) for receiving the first immunization = 7.3; RR for receiving the second immunization = 3.8). Several health beliefs were also associated with receiving vaccinations. CONCLUSIONS: The results of our study indicate that hepatitis B vaccination programs can be improved through such steps as providing vaccinations at a convenient site, educating adolescents about hepatitis B risk factors, and emphasizing the difficulty of treating hepatitis B infection.

Declining levels of erythrocyte folate during the postpartum period among Hispanic women living on the Texas-Mexico border.

Hispanic women have higher parity and shorter interbirth intervals than women of other ethnic groups. Thus, they are more likely to become pregnant relatively soon after giving birth, which may place these women at risk of low or deficient levels of specific nutrients. Folic acid is of particular concern because recent studies suggest that maternal use of folic acid supplements may be associated with better reproductive outcomes. The purpose of this study was to assess folic acid levels in postpartum Hispanic women. Using a cross-sectional design, we measured erythrocyte folate values for 188 low-income Hispanic women 1-12 months postpartum who were receiving services at the Women, Infants, and Children (WIC) clinics in El Paso, Texas. An interview was administered to collect information on diet, vitamin use, and method of infant feeding. Mean erythrocyte folate levels decreased from >1300 ng/ml during the first 4 months postpartum to a low of 1017 ng/ml by 12 months postpartum, for an overall decrease of approximately 23% (p = 0.004). Use of postpartum vitamin supplements was significantly associated with higher folate levels. However, only 35% of mothers used vitamins beyond 1 month postpartum. Study results suggest that these mothers may be at risk of developing low or deficient levels of folic acid during the postpartum period. Educational campaigns targeting these women as well as other groups of postpartum women should encourage them to comply with the U.S. Public Health Service recommendation that women of childbearing age consume 0.4 mg of folic acid daily.

The effect of detergent on the structure and composition of chlorosomes isolated from Chloroflexus aurantiacus.

Isolated chlorosomes, treated with the detergent lithium dodecyl sulfate (LDS), can be separated into two green fractions by agarose gel electrophoresis. One fraction contains chlorosomes with a full complement of proteins and antenna BChl c absorbing at 740 nm, but with a more spherical form than the normal ellipsoid shape observed in control chlorosomes. The second fraction was completely devoid of proteins but had a similar absorption spectrum. Electron micrographs of the protein-free fraction indicated the presence of stain-excluding spheres with overall dimensions resembling those of intact chlorosomes (40-100 nm). These spheres are probably micelles of BChl c liberated from the chlorosomes during the detergent treatment, since similar structures could be produced when purified BChl c, dissolved in 1-hexanol, was dispersed in buffer, producing an aggregate absorbing at 742 nm. These results suggest that the chlorosome proteins are not required to produce an arrangement of BChl c chromophores which gives rise to a 740 nm absorption peak resembling that of intact chlorosomes. It seems probable, however, that proteins have a role in determining the overall shape of the chlorosome. Treatment with cross-linking reagents did not prevent the detergent-induced changes in chlorosome morphology.

Gene encoding the 5.7-kilodalton chlorosome protein of Chloroflexus aurantiacus: regulated message levels and a predicted carboxy-terminal protein extension.

The major light-harvesting pigment of the green filamentous bacterium Chloroflexus aurantiacus is bacteriochlorophyll (Bchl) c, localized in chlorosomes attached to the inner surface of the cytoplasmic membrane. Chlorosomes consist of four polypeptides and associated pigments and lipids. Previous studies of the inducible assembly of the photosynthetic apparatus had indicated that the major chlorosomal polypeptides are present as high-molecular-weight aggregates before the appearance of mature chlorosomes, and a mechanism for posttranslational processing of a polyprotein had been proposed. We have isolated the gene (csmA) encoding the 5.7-kilodalton chlorosomal polypeptide from C. aurantiacus in order to determine whether this protein is synthesized as part of a polyprotein. Analysis of the nucleotide sequence of csmA indicates that the gene is not large enough to encode more than one known chlorosome polypeptide. Transcriptional analysis indicates that csmA is transcribed as a small message whose abundance is regulated in response to oxygen, so that no csmA message is detectable in cells grown aerobically in the dark. Comparison of the sequence predicted by csmA with the peptide sequence of the Bchl c binding protein purified from chlorosomes indicates that this protein is synthesized with a carboxy-terminal extension of 27 amino acids. We discuss possible roles for this carboxy-terminal extension in the assembly of chlorosomes.

Oxygen regulation of development of the photosynthetic membrane system in Chloroflexus aurantiacus.

Oxygen levels which control induction of the assembly of the pigment-protein photosynthetic polypeptides in dark-grown Chloroflexus aurantiacus were determined. The induction signal by low-oxygen tension is not directly related to the respiratory competence of these photosynthetic cells. Cytochrome c554, the primary electron donor to P865+ of the reaction center, is not present in dark-grown respiratory cells but is induced in parallel with bacteriochlorophylls a and c and at similar oxygen partial pressure. The development of these components of the photosynthetic apparatus and its electron transport chain is completely independent of the presence of any detectable light or bacteriochlorophyll c or a pigments in C. aurantiacus.

The protochlorophyllide holochrome of barley (Hordeum vulgare L.). Isolation and characterization of the NADPH:protochlorophyllide oxidoreductase.

The NADPH:protochlorophyllide oxidoreductase of barley has been solubilized from etioplast membranes and purified to apparent homogeneity. The highest specific activity measured for the purified enzyme was 1.6 nmol chlorophyllide formed (mg protein-1) per flash. Electrophoretic analysis of the purified enzyme on sodium dodecylsulfate/polyacrylamide gels revealed only one polypeptide of Mr 36000. Durig glycerol gradient centrifugation the enzyme migrates as a low-molecular-weight component. It is proposed that each enzyme molecule contains only one polypeptide chain. Assuming a molecular weight of 36000 for the enzyme, it was calculated that two or three protochlorophyllide molecules are bound to each enzyme molecule.

Comparison of Light-dependent Oxygen Uptake, Protochlorophyll(ide)-650 Photoconversion, and Chlorophyll Disappearance in Wheat Etioplasts.

Red light exposures given to dark-grown wheat seedlings (Triticum aestivum L.) prior to etioplast isolation reduced the ability of these organelles to consume O(2). The same preharvest red light exposures also decreased protochlorophyll(ide) content of etioplasts. In addition, regeneration of both O(2) uptake rates as well as protochlorophyll(ide) levels followed a parallel time course. These similarities suggested that photoconversion of protochlorophyll(ide)-650 to chlorophyll(ide) may mediate some process with O(2) as the electron acceptor. This process appears to involve photooxidation of nonphotoconvertible protochlorophyll(ide) as well as of newly formed chlorophyll(ide). This hypothesis is further supported by the observations that: (a) the in vitro light induced O(2) uptake phenomenon was observed in solubilized protochlorophyll(ide) holochrome preparations; and (b) photoinduced O(2) uptake was reduced to zero rate by light exposure time equivalent to that required for chlorophyll(ide) and nonphotoconvertible protochlorophyll(ide) destruction.

Light-mediated Oxygen Uptake Measured in Wheat Etioplasts.

An in vitro O(2) assay was used to measure early response of wheat (Triticum aestivum L.) etioplasts to light. A transient photoinducible O(2) uptake occurred when dark-grown etioplasts were initially exposed to light. The rate of inducible O(2) consumption was dependent on both the intensity of light and the quantity of organelle protein present. Higher light intensities resulted in greater O(2) utilization per minute, and a greater quantity of organelle protein in the sample resulted in an increased rate of O(2) uptake under the same light intensity conditions. Experiments with various plant tissues as well as with mitochondrial respiratory inhibitors indicated that etioplasts are the organelles responsible for the photoinduced O(2) uptake phenomenon. A preliminary action spectrum study revealed that wavelengths 640 to 680 nm resulted in maximum O(2) uptake. This indicated the presence of an etioplast red light receptor pigment which induces O(2) uptake in etioplasts.