Intakes of retinol and carotenoids and its determining factors in the Red River Delta population of northern Vietnam.

OBJECTIVE: To describe the household intakes of retinol and carotenoids and social economic factors determining their intakes. SUBJECTS: Data on a total of 1001 households (771 in rural areas and 230 in urban areas) were used in the analyses. Interviewed person was household food preparer. RESULTS: Mean (s.d.) intake of carotenoids was 4178 (3154) microg/capita/day in rural and 4208 (3408) microg/capita/day in urban areas and intake of retinol was 101 (275) microg/capita/day in rural and 201 (470) microg/capita/day in urban areas. Multivariate analyses show that the subjects in households with four or more members consume about 700 microg carotenoids less compared to households with less than three members. Households with a higher expenditure (fourth quartile) consumed about 100 microg retinol/day more than those with a lower expenditure (first quartile). CONCLUSION: Carotenoids from plant food sources is the main source of vitamin A intake of the population and its main determinants are household expenditure and size of household. Food fortification and dietary diversification with special emphasis on promotion of consumption of animal foods should be key strategies for overcoming vitamin A deficiency in Vietnam.

Resting metabolic rate of Vietnamese adolescents.

OBJECTIVE: To evaluate the FAO/WHO/UNU equations for predicting resting metabolic rate (RMR) in Vietnamese adolescents. DESIGN: A cross-sectional study involving healthy subjects was carried out at the Basic Nutrition Department, National Institute of Nutrition, Vietnam. The RMR was measured by indirect calorimetry and anthropometric indices were recorded. Equations derived by linear regression of RMR and body weight were compared to the FAO/WHO/UNU (1985) predictive equations. SUBJECTS: A total of 110 subjects who had normal body mass index (5-85 percentile) and divided into two groups by sex. RESULTS: Mean RMRs (MJ/kg/day) were 0.1146+/-0.0054 for males and 0.1062+/-0.0103 for females. Compared to the FAO/WHO/UNU equation, our findings were 7.8% and 11.7% lower in the two groups, respectively (P<0.001). CONCLUSION: Our findings suggest that the FAO/WHO/UNU equations may overestimate RMR in Vietnamese adolescents. Further studies on establishing reference of daily energy needs for Vietnamese adolescents should be carried out.

Efficacy of combined iron and zinc supplementation on micronutrient status and growth in Vietnamese infants.

OBJECTIVE: To evaluate the effect of combined iron-zinc supplementation on micronutrient status, growth and morbidity. DESIGN: Randomized, double-masked, placebo-controlled supplementation trial. SETTING: Rural district of Que Vo, in the Red River Delta in Vietnam. SUBJECTS: A total of 915 breast-fed infants aged 4-7 months were included and 784 completed the study. INTERVENTIONS: The Fe-group received daily and for a 6-month period 10 mg of iron, the Zn-group 10 mg zinc, the Fe-Zn group 10 mg iron+10 mg zinc and the placebo group a placebo. Hemoglobin (Hb), serum ferritin (SF) and zinc (SZn), and anthropometry were measured before and at the end of the intervention. Morbidity was recorded daily. RESULTS: Changes of Hb and SF were higher in both Fe and Fe+Zn groups (respectively 22.6 and 20.6 g/l for Hb; 36.0 and 24.8 microg/l for SF) compared to Zn and placebo groups (Hb: 6.4 and 9.8 g/l; SF: -18.2 and -16.9 microg/l, P<0.0001). SZn increased more in Zn group (10.3 micromol/l) than in Fe+Zn group (8.0 micromol/l, P=0.03) and more in these groups compared to Fe and placebo groups (1.6 and 1.2 micromol/l, P<0.0001). Weight gain was higher in the Zn group. No significant effects of supplementations on growth in length or morbidity. CONCLUSIONS: Combined iron-zinc supplementation had a positive effect on iron and zinc status in infants. However, the positive effect of zinc alone on SZn and weight would indicate a negative interaction of iron when added to zinc supplements. SPONSORSHIP: UNICEF New York.

FAO/WHO/UNU equations overestimate resting metabolic rate in Vietnamese adults.

OBJECTIVE: To evaluate the FAO/WHO/UNU equations for predicting resting metabolic rate (RMR) in Vietnamese adults. DESIGN: A cross-sectional study with healthy subjects was carried out at the Basic Nutrition Department, National Institute of Nutrition, Vietnam. RMR was measured by indirect calorimetry, and anthropometric indices were recorded. Equations derived by linear regression of RMR vs body weight were compared to the FAO/WHO/UNU 1985 predictive equations. SUBJECTS: A total of 188 subjects (98 males and 90 females) had a normal body mass index (BMI) and were divided into four groups by sex and age (male and female subjects 18-29 and 30-60 y old). RESULTS: Mean RMR (MJ/kg/day) in males was lightly significant by higher than that in female subjects in the 18-29 y old age group (0.1074+/-0.0100 vs 0.0965+/-0.0123) and the same result was seen in the 30-60 y old group (0.1018+/-0.0114 vs 0.0922+/-0.0129). However, differences were not statistically significant in the two age groups. Compared to the FAO/WHO/UNU equation, our findings were 7.4, 9.0, 11.7, and 13.5% lower in the four groups, respectively (P < 0.001). CONCLUSION: Our findings suggest that the FAO/WHO/UNU equations may overestimate RMR in Vietnamese adults. Further studies examining the relationship between body weight and RMR are needed, and establishing new predictive equations for RMR in Vietnamese should be a priority.

An immunochromatographic serological assay for the diagnosis of Mycobacterium tuberculosis.

A rapid serological test for tuberculosis (TB) infection was designed using antigens specific to Mycobacterium tuberculosis. Tuberculosis infection, TB vaccination and exposure to environmental Mycobacteria cannot be distinguished using skin tests based on tuberculin protein derivatives. The standard diagnostic techniques such as skin tests, X-rays and DNA techniques are time consuming, expensive, and not practical for screening large populations. We used the 38, 63, 64, 14, 59-kDa antigens of M. tuberculosis to develop a rapid immunochromatographic test kit. This study evaluates the diagnostic potential of the rapid test kit using TB positive and TB negative serum samples from various hospitals in India. The samples were obtained from patients infected with or exposed to bacteria and viral pathogens. The results demonstrated that the combination of antigens improved the diagnostic specificity and sensitivity. The specificity of the test was 99.42% with sensitivity of 98.52% (n = 241). In case of multiple infections, the specificity was 93.15% with a low sensitivity of 73.52% n = 141). The test kit may offer an improved alternative to purified protein derivative (PPD). This rapid TB test kit may be a useful tool for first-line testing of suspected cases, epidemiological studies and in designing a quality health system to reduce health hazards in resource-poor countries.

Genotypic and phenotypic analysis of human immunodeficiency virus type 1 isolates from patients on prolonged stavudine therapy.

Development of stavudine resistance was studied using human immunodeficiency virus type 1 isolates from 13 patients treated with stavudine for 18-22 months. Drug sensitivity testing on 11 of these pre- and posttherapy isolates identified only 2 posttreatment isolates with decreased stavudine sensitivity (ED50s < 4-fold higher than the average pretreatment ED50). Genotypic analysis of all 13 pairs of isolates identified multiple mutations in the reverse transcriptase (RT) gene. However, no genetic basis was identified to account for the observed changes in stavudine susceptibility. A recombinant virus containing the entire RT gene of the posttherapy isolate displaying the greatest resistance remained sensitive to stavudine. Five of the stavudine posttreatment isolates developed resistance (9- to 176-fold) to zidovudine, although the relationship between stavudine treatment and the appearance of zidovudine resistance remains unexplained. Analysis of 10 additional pairs of isolates did not confirm this relationship. The low frequency and modest degree of change in stavudine sensitivity following prolonged treatment is very encouraging.

Morphogenesis of human immunodeficiency virus type 1.

Human immunodeficiency virus (HIV) has been implicated as the etiologic agent of acquired immunodeficiency syndrome and is a member of the sub-family Lentivirinae within the family Retroviridae. HIV type 1 (HIV-1) contains three major genes, gag, pol and env, which code for (1) core proteins, (2) a protease, reverse transcriptase and integrase, and (3) envelope glycoproteins, respectively. The core proteins p17, p24 and p15 are derived from gag precursor, p55, by endoproteolytic cleavage. The two nucleic-acid-binding proteins p7 and p9 are synthesized from p15 by proteolytic cleavage. These two structural proteins are apparently needed for the ribonucleoprotein-core formation. The envelope glycoproteins gp120 and gp41 (gp120-gp41 complex) are also generated by cleavage env precursors, gp160. The assembly of HIV-1 particles, like other retroviruses, appears to involve the association of the env precursor gp160 with the gag proteins. There are several factors which influence the assembly and budding process of HIV-1. In this article, we describe important events in HIV-1 morphogenesis and factors which influence this aspect of the HIV-1 life cycle.

Localization of hepatitis A virus antigen to specific subcellular fractions of hepatitis-A-infected chimpanzee liver cells.

The localization of hepatitis A virus antigen to specific subcellular fractions of infected chimpanzee liver cells was studied by solid-phase radioimmunoassay following a mild subcellular fractionation procedure designed to separate various organelles from the cytosol and the nuclei. Most of the antigenic activity (93%) was evenly divided between the cytosol fraction and the microsomal suspension. Within the microsomal fraction, more than 75% of the detectable antigen was associated with the smooth endoplasmic reticulum. Less than 4% of the total antigenic activity was localized to the nucleus. These data provide additional evidence that replication of hepatitis A virus occurs primarily within the cytoplasm of the host cell in close association with cellular membranes, consistent with that observed for other members of the genus Enterovirus.

Posttransfusion hepatitis type A.

Hepatitis A virus (HAV) transmission through blood is a rare but potential cause of posttransfusion hepatitis. We can now document such a case supported by laboratory evidence of HAV in the donor blood. A 10-year-old girl manifested icteric hepatitis A 31 days after receiving a single unit of packed RBCs from a donor who subsequently experienced hepatitis A and died in hepatic failure. Hepatitis A virus antigen was detected in the donor's hepatocytes and in plasma obtained from the original donor unit. The density in cesium chloride of the HAV antigenic activity from the liver and plasma ranged from 1.33 to 1.37 g/cu cm, which is similar to that reported for infectious HAV particles. The implicated donor plasma had normal aminotransferase levels and was negative for antibody to HAV. Inoculation of this plasma into a chimpanzee resulted in the development of hepatitis A 23 days later based on the appearance of fecal HAV antigen, hepatitis, and IgM anti-HAV seroconversion. These data clearly document the presence of HAV in the donor sample that produced posttransfusion hepatitis A.

The fate of parental herpesvirus DNA after infection with normal and photoinactivated virions.

The fate of the 3H-dT-labelled parental DNA of normal and photoinactivated herpes simplex virus type 1 (KOS strain) was followed for 8 h after infection. The sedimentation coefficients of parental virus DNA from cells infected with normal virons increased and became associated with the replicative intermediates of HSV-1 DNA. When cultured in 5-bromodeoxyuridine-containing medium, the buoyant density of the normal parental virus DNA shifted to the hybrid region (containing heavy and light molecules) of the caesium chloride density gradient. The parental virus DNA of photoinactivated virions, however, degraded quickly and did not participate in progeny virus DNA replication.

Photodynamic treatment of herpes simplex virus during its replicative cycle.

Photodynamic treatment of herpes simplex virus type 1-infected hamster embryo fibroblasts (LSH strain) with a low concentration of proflavine (0.08 mug/10(5) cells per ml), a 3-9-diamine acridine dye, inhibited production not only of infectious progeny but also of virion particles. However, there was no appreciable inhibition of viral or cellular DNA synthesis, even when the infected cells were repeatedly exposed to this low concentration of dye and light during the replication cycle of the virus. It thus appears that photodynamic treatment of infected cells interferes with the processes involved in virus maturation.

Photodynamic inactivation of antigenic determinants of single-stranded DNA bacteriophage phi chi 174.

Bacteriophage phiX174 when photodynamically inactivated (i.e., when rendered unable to produce plaques as a result of exposure to visible light in air in the presence of proflavine) progressively lost their capacity to bind efficiently with homologous antiserum. Such loss of serum-blocking power was evident with heat-inactivated but not with UV-irradiated phage. The ability of the phages to adsorb to host cells, however, remained practically unaltered even after photodynamic inactivation. It thus appears that photodynamic damages in the so-called "jacket" component of the phiX174 coat proteins are partly responsible for the loss of plaque-forming ability, whereas the "spikes" are either poor antigens or insensitive to photodynamic treatment.