An experimental strategy validated to design cost-effective culture media based on response surface methodology.

For any fermentation process, the production cost depends on several factors, such as the genetics of the microorganism, the process condition, and the culture medium composition. In this work, a guideline for the design of cost-efficient culture media using a sequential approach based on response surface methodology is described. The procedure was applied to analyze and optimize a culture medium of registered trademark and a base culture medium obtained as a result of the screening analysis from different culture media used to grow the same strain according to the literature. During the experiments, the procedure quantitatively identified an appropriate array of micronutrients to obtain a significant yield and find a minimum number of culture medium ingredients without limiting the process efficiency. The resultant culture medium showed an efficiency that compares favorably with the registered trademark medium at a 95% lower cost as well as reduced the number of ingredients in the base culture medium by 60% without limiting the process efficiency. These results demonstrated that, aside from satisfying the qualitative requirements, an optimum quantity of each constituent is needed to obtain a cost-effective culture medium. Study process variables for optimized culture medium and scaling-up production for the optimal values are desirable.

Factor structure of the Beck Depression Inventory-Second Edition (BDI-II) with Puerto Rican elderly

The Beck Depression Inventory-Second Edition (BDI-II; (1) is one of the most useful measures for depressive symptomatology in many countries (2). The psychometric properties of this inventory, however, have not been reported with Puerto Rican elderly. This paper reports, exploratory psychometric results with a sample of 410 elderly Puerto Rican (65 years and older; men=94, women=316). The assessment of the construct validity of the BDI-II yielded four factors accounting for 52of total variance and an internal reliability coefficient (alpha Cronbach) of .89. A factor analysis with the 21 items of the BDI-II was performed using principal component analysis as the extraction method and Varimax rotation. This analysis revealed that the BDI-II was a good measure of the dimensions of depressive symptomatology in the present sample, which resembled prior findings reported with the general Puerto Rican Population (3). This study also reports further data supporting the reliability, validity, and practical utility of the BDI-II for the Puerto Rican population including elders. Implications for potential research with minorities and clinical uses of the BDI-II are also discussed.

Environmental pesticide exposure in Honduras following hurricane Mitch.

OBJECTIVE: To investigate whether environmental contamination occurred in the wake of hurricane Mitch (30-31 October 1998), we conducted a population-based cross-sectional household survey in the barrio of Istoca, Department of Choluteca, Honduras. The goals were to evaluate chemical contamination of potable water and the extent of human exposure to chemicals as a result of extensive flooding. METHODS: The survey consisted of an environmental exposure assessment, which included assaying water and soil samples for contaminants, and taking blood and urine samples from 45 adolescents aged 15-18 years. We also made a subjective questionnaire assessment of 155 households. FINDINGS: There was significant contamination of the soil in Istoca, but no water contamination in the aftermath of hurricane Mitch. The soil levels of chlopyrifos and parathion were 30- and 1000-times higher, respectively, than the Environmental Data Quality Level. However, the most striking finding was the detection of elevated levels of chlorinated and organophosphate pesticides in adolescents. Toxicological analyses of serum specimens showed that 51% of the samples had elevated levels of 1,1-dichloro-2,2-bis-(p-chlorophenyl) ethylene (p,p-DDE) (range, 1.16-96.9 ng/ml) (US reference mean = 3.5 ng/ml) in adults). Dieldrin levels > 0.2 ng/ml were also present in 23% of the serum specimens (serum levels of this analyte in US adolescents are < 0.2 ng/ml). Of 43 urine samples analysed for organophosphate metabolites, 18.6% contained diethyl phosphate (DEP) at levels which were greater that the reference mean of 6.45 micrograms/g creatinine. We also detected elevated levels of p-nitrophenol (p-NP) and of 3,5,6-trichloro-2-pyridinol (3,5,6-TCPY) in 91% and 42% of the samples, respectively. CONCLUSIONS: The elevated levels of chlorinated pesticides were surprising, since although these substances were banned in Honduras 15 years ago it appears that they are still being used in the country. Moreover, elevated levels of organophosphates were detected in the study adolescents even three weeks after the hurricane. Since these chemicals are usually cleared from the body quickly, our data suggest that the adolescents face an ongoing threat from pesticide exposure.

A defined sequence within the 3' UTR of the areA transcript is sufficient to mediate nitrogen metabolite signalling via accelerated deadenylation.

Nitrogen metabolism in Aspergillus nidulans is regulated by AREA, a member of the GATA family of transcription factors. One mechanism that modulates AREA activity involves the rapid degradation of the areA transcript when sufficient NH4+ or Gln are available. This signalling mechanism has been shown to require a region of 218 nucleotides within the 3' untranslated region of areA mRNA. We demonstrate that this region functions independently in a heterologous transcript and acts to accelerate degradation of the poly(A) tail, which in turn leads to rapid transcript degradation in response to the addition of NH4+ or Gln to the growth medium. areA transcript degradation is inhibited by cycloheximide, but this is not a general consequence of translational inhibition. We believe that this is the first reported example in which specific physiological signals, acting through a defined sequence within a transcript, have been shown to promote accelerated poly(A) degradation, which in turn triggers transcript degradation.

[Assessment of accessibility to health services facilities]. / Evaluación de la accesibilidad en los servicios de salud.

OBJECTIVE: To assess health care access integrating the availability of resources, medical institution and the patient point of view. SETTING: Nuevo León, México. MEASUREMENTS AND MAIN RESULTS: A random sample of patients were interviewed about their perceptions on different barriers, which also were assessed for the institution utilizing the corresponding indicator. Availability of resources were also measured for every primary and secondary medical care unit of the greatest Mexican health care system in Nuevo León. It was observed a 70% access; 70% for primary care and 73% for secondary care. Availability of human resources was an important factor but barriers as observed by the institution were the most important (waiting time and traveling cost). Barriers were rated different by the institution and the patient. CONCLUSIONS: The combination of institutional barriers, patient barriers and resources for assessing health care access is discussed.

[Tobacco consumption in the population insured by Mexican Institute of Social Security]. / Consumo de tabaco en la población derechohabiente del Instituto Mexicano del Seguro Social.

OBJECTIVE: To determine the prevalence of tobacco consumption among the active insured population of the Mexican Social Security Institute. MATERIAL AND METHODS: A cross-sectional study in which the active insured population from the 36 political delegations was interviewed by means of a structured and self-applicable questionnaire on tobacco consumption, age of initiation, amount of cigarettes consumed and suspension. RESULTS: The sample consisted of 45 117 subjects, of which approximately half were men and half women. Smoking prevalence in men was 40% and in women, 17.6%. Prevalence was highest in the north of the country. There is an effect of age on tobacco consumption and more than half started smoking during adolescence. CONCLUSIONS: Smoking prevalence was found to be high, however, the average number of cigarettes is low. Suspension index is low. Public health measures are necessary to diminish this addiction.

[Epidemiologic aspects of the aged at the Mexican Institute of Social Security]. / Aspectos epidemiológicos del adulto mayor en el Instituto Mexicano del Seguro Social.

OBJECTIVE: The objective of this study is to present dynamic changes within the population over 65 years of age who are covered by the Mexican Institute of Social Security (MISS), through morbidity and mortality analysis, during the last 6 and 10 years respectively. MATERIAL AND METHODS: Based on data from the Epidemiologic Bulletins from 1990 to 1995 and from 1985 to 1994, the morbidity and mortality rates, respectively, were calculated for the Mexican population over 65 who are covered by the MISS. Incidence of diseases was used as a measure of occurrence and the ratio of morbidity and mortality rates was calculated as the measure of effect. RESULTS: An epidemiological transition exists, with a tendency towards aging among this population. In terms of morbidity, infectious and chronic diseases coexist; as for mortality, chronic-degenerative diseases predominate. CONCLUSIONS: This represents a challenge for health care within institutional services, as this population group begins to compete with other priority groups and emergency needs. Epidemiological surveillance and research is essential to support decision-making.

[Molecular biology in the pathogenesis of Shigella sp. and enteroinvasive Escherichia coli]. / Biología molecular en la patogenia de Shigella sp. y Escherichia coli enteroinvasiva.

Shigella sp and Escherichia coli (EIEC) are casual agents of bacillary dysentery, mainly in developing countries. Shigella and EIEC share biochemical, antigenic and genetic properties and probably they have the same mechanism of pathogenicity. Both species harbor a 120-140 megadalton plasmid, which is associated to the virulence and whose expression is regulated by chromosomal genes. Shigella sp and EIEC invade colonic epithelium and present virulence auxiliary factors, such as mucinases, superoxide dismutase and aerobactine production. On the other hand, cytotoxin production contributes to the illness' severity. The first step in invasion of the colonic mucosa is epithelium adherence, followed by endocytosis, lysis of the phagocytic vacuole, intracellular multiplication, intra-intercellular spread and killing of the host cell. Identification of these invasive organisms is carried out with the Sereny test, chicken embryo lethality and invasion to culture cells assays, DNA probe hibridization, polimerase chain reaction, ELISA, Congo red binding, and biochemical and serological tests.

Aedes albopictus in Muzquiz city, Coahuila, Mexico.

Aedes albopictus was found in M. Muzquiz, Coahuila, Mexico, in the summer of 1993. Aedes albopictus larvae were collected in tires and bottles at low density. Aedes aegypti, Toxorhynchites theobaldi, Culex quinquefasciatus, and Culiseta incidens were collected in the same containers.

Personality characteristics analysis in couples undergoing artificial insemination.

The personality characteristics of 40 couples admitted into an artificial insemination scheme have been analysed. The personality study was carried out using Cattell's questionnaire 16 PF (form C) and EPI questionnaire (Eysenck Personality Inventory). The results show significant statistical differences between males and females with a greater conformity with the group, in women; women are also bolder and more disciplined from an emotional point of view, whereas men are more radical.

[Epidemiology of cervical cancer at the Mexican Institute of Social Security]. / Epidemiología del cáncer cervicouterino en el Instituto Mexicano del Seguro Social.

In order to study the secular trend and age and geographic distribution of cervical cancer at the Mexican Institute for Social Security, an ecologic study was carried on. During the last 10 years cervical cancer has been the second most common neoplasia, being the leading one in women. For those between 30 and 44 years old it is the third cause of death, and one of the first ten in all age groups until 64. Mortality has shown a stable trend for the last 15 years, in a range from 3.3 to 4.5 deaths per 100,000 inhabitants. Mortality rates increase with age. There is a fine-fold increase in the risk of death for women 40 to 49 years old (CI 95% 4.2-6.4%) and a tenfold increase for those over 80, (CI 95% 7.3-12.6) when taking those under 40 years old as a reference group. In 1989, the cervical cancer incidence was 9.7 cases for each 100,000 person-years. Morbidity and mortality are unequally distributed along the country. There is a need for the development of research in order to know better the occurrence of this disease as well as how known risk factors affect it.

Detection of serum inhibitory factor for lymphocyte stimulation in chronic viral hepatitis: relationship with the replication level.

Sera from 111 patients with chronic viral hepatitis and from 55 cases with other liver disorders were assayed for serum inhibitory factor. The prevalence of this immunosuppressive factor was very similar between chronic hepatitis B (61%), chronic hepatitis delta (57%) and chronic hepatitis C (68%). At the same time, serum inhibitory factor was never detected in the other disorders studied. The presence of this inhibitory factor was detected in a significantly higher percentage (p less than 0.05) of HBeAg, HBV-DNA positive cases (75%) than in anti-HBe positive, HBV-DNA negative cases (44.4%). In chronic hepatitis delta, this immunosuppressive factor was also related to HDV-RNA positivity. The detection of this serum immunosuppressive factor in chronic viral hepatitis and its association with a high viral replication level implies a possible role of this factor in the immune pathogenic mechanism in infectious viral hepatitis.

Influence of hepatitis delta virus replication in the presence of hepatitis B virus DNA in peripheral blood mononuclear cells.

The presence of hepatitis B virus DNA was studied in peripheral blood mononuclear cell samples from 259 HBsAg carriers (229 anti-hepatitis delta negative, 30 anti-hepatitis delta positive), 16 anti-HBc-positive HBsAg-negative patients and 30 patients without hepatitis B virus markers. Hepatitis B virus DNA sequences were detected in peripheral blood mononuclear cell from 115 (44.4%) of the chronic HBsAg carriers and from two (12%) of the anti-HBc-positive, HBsAg-negative patients. In anti-hepatitis delta-negative patients, viral DNA was positive in peripheral blood mononuclear cell from 74 (46%) and from 24 (35.5%) with and without serum HBV-DNA, respectively. With respect to anti-hepatitis delta-positive patients, viral DNA was found in peripheral blood mononuclear cell in 8 of 13 (61.5%) of the patients with circulating hepatitis delta virus RNA and in 9 of 17 (53%) of the hepatitis delta virus RNA-negative subjects. Regarding hepatitis B virus DNA in serum and peripheral blood mononuclear cell, 71% (5 of 7) of the patients with serum hepatitis B virus DNA had this marker in peripheral blood mononuclear cell, whereas 52% (12 of 23) of the patients without serum hepatitis B virus DNA had hepatitis B virus DNA in peripheral blood mononuclear cell. A Southern blot analysis was also carried out on peripheral blood mononuclear cell samples from 30 patients. Hepatitis B virus DNA was detected in 16 patients as free forms, in 12 patients as dimers and free forms and as free circular together with free linear forms in the remaining two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Presence of HBV-DNA in peripheral blood mononuclear cells from anti-HIV symptomless carriers.

The presence of hepatitis B virus DNA (HBV-DNA) in the peripheral blood mononuclear cells (PBMC) of 29 anti-HIV symptomless carriers (eleven HBeAg positive, eleven anti-HBe positive and seven HBsAg negative) and of 40 anti-human immunodeficiency virus (HIV)-negative patients (15 HBeAg positive, 15 anti-HBe positive and ten HBsAg negative) has been studied by dot-blot and Southern blot hybridization. HBV-DNA has been found in similar proportions in both anti-HIV-positive and negative patients (36% and 46%, respectively, in the HBeAg positive group and 27% and 37% in the anti-HBe positive group). No HBV-DNA was detected in the PBMC of the HBsAg-negative patients. No relation has been observed between the presence of HBV-DNA in the PBMC of the anti-HIV-positive patients and the detection of HIV antigen (HIV Ag), number of CD4 cells or the CD4/CD8 ratio. In summary, the presence of HBV-DNA in the PBMC of anti-HIV symptomless carriers does not seem to imply that the patient's clinical state has worsened.

Decolouration of the lens pigment in senile nuclear cataract.

Human cataract lens proteins can be bleached by exposure to sodium borohydride (NaBH4), sodium cyanoborohydride (NaCNBH3), or hydrogen peroxide (H2O2). The decolouration resulting from these treatments could be monitored by a change in absorbance at 350 nm. At pH 12 the magnitude of the absorbance change increased in proportion with the severity of the nuclear cataract in the case of NaBH4 and H2O2 treatments, but not in the case of NaCNBH3 treatment. The rate of change in absorbance at 350 nm following exposure to the different reagents was used to evaluate three model systems for senile nuclear cataract. These model systems utilized calf lens proteins which had been tanned by exposure either to 3-hydroxyanthranilic acid, dopa/tyrosinase, or ultraviolet light.