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Biomedical subjects

E Gaitan

Publications and source records attributed to E Gaitan.

At least 37 records · Page 2Linked to original sources
PubMed1990

Goitrogens in food and water.

Epidemiologic and experimental evidence reviewed in this article emphasizes the complex and multifactorial etiology of endemic goiter. The important role of iodine deficiency as an etiologic factor in endemic goiter is firmly established, but there is evidence that other environmental factors can play an equally important role in the pathogenesis of this condition. Chemical categories, sources, and sites of action of the various classes of naturally occurring goitrogens and antithyroid agents are reviewed in this article. Evidence of the presence of these compounds in foodstuffs and drinking water is discussed. Bacterial contamination of water supplies also appears to be important in the development of goiter. Microorganisms appear to intervene in the biosynthesis and degradation of organic goitrogenic pollutants or may induce thyroid growth-promoting activity in the host, or both. Malnutrition and poor socioeconomic conditions, as for iodine deficiency, enhance the action of environmental goitrogens. Thus, a coordinated multidisciplinary approach is essential to solving this public health problem.

Antithyroid Agents↗
PubMed1990

Intervention policy in endemic goitre areas.

The multifactorial nature and complex interactions of regionspecific environmental conditions with host factors in the pathogenesis of endemic goitre constitute a major challenge to the understanding and control of the problem in endemic areas. However, to control and prevent this important public health problem, the most obvious but difficult initial step requires substantial socioeconomic improvements in the affected areas of less developed countries, including, first, provision of efficient iodine prophylaxis programs, second, diversification of dietary constituents with adequate daily protein-calorie intake, and third, institution of proper sanitary conditions with effective water treatment to eliminate organic and bacterial pollutants. This last intervention is also a requirement to control and prevent goitre in the iodine-sufficient more developed countries. In this regard, more research is needed to provide effective ways of water treatment that can be applied in individual households or at the community level.

Age Factors↗
PubMed1989

The male factor in the etiology of cervical cancer among sexually monogamous women.

To address the hypothesis that male sexual behavior may affect the etiology of invasive cervical cancer, a case-control study was undertaken in Panama, Costa Rica, Colombia and Mexico. The study enrolled husbands of those women with invasive cervical cancer and of those age-matched controls who reported only one lifetime sexual partner. A total of 204 case and 485 control husbands (78% and 72%, respectively, of identified husbands) were interviewed, clinically examined, and had penile swabs taken for papillomavirus assays. Risk increased significantly (p = 0.005) with the number of sexual partners reported by the husband (RR = 2.0 for 26+ vs. less than 6 partners). Low educational status of the husband was also an important predictor of risk, possibly indicating the role of unmeasured aspects of sexual behavior. Visits to prostitutes, circumcision status and sexually transmitted disease histories were not important predictors of risk, but evidence from clinical examination indicated that poor genital hygiene may be involved. Human papillomavirus (HPV) expression as defined by filter in situ hybridization was detected in 20-23% of subjects and, except in the small group with both HPV types 6/11 and 16/18, was not related to risk. This may reflect sampling problems in the male or the importance of host factors which enhance viral carcinogenicity in the female.

Circumcision, Male↗
PubMed1989

Invasive cervical cancer and smoking in Latin America.

A case-control study of 667 patients with invasive squamous cell carcinoma of the cervix and 1,430 controls from four Latin American countries showed an age-adjusted relative risk (RR) of 1.2 [95% confidence interval (CI) = 1.0-1.4] for women who had ever smoked, with risk rising to 1.7 (95% CI, 0.8-3.6) for women who smoked greater than or equal to 30 cigarettes per day. The associations were practically eliminated after adjustment for the number of sexual partners and alcohol consumption, probably a surrogate for an unidentified life-style risk factor. Some excess risk persisted among women who smoked for extended periods (RR = 1.5 for greater than or equal to 40 yr), as well as those who began smoking at older ages (RR = 1.7 for greater than 30 yr), which suggests a late-stage effect. In addition, among women who tested positive for human papillomavirus (HPV) type 16 or 18 by filter in situ hybridization, there was an increased risk for women who had ever smoked and a dose-response relationship with the number of cigarettes smoked (adjusted RRs compared with HPV-negative nonsmokers = 5.0 for HPV-positive nonsmokers, 5.5 for less than 10 cigarettes/day, and 8.4 for greater than or equal to 10 cigarettes/day). In contrast, HPV-negative women had no increased risk associated with smoking. These results, from a high-incidence area where intensive smoking among women is still relatively rare, suggest that smoking has a limited effect on cervical cancer risk, possibly only among women with specific types of HPV.

Age Factors↗
PubMed1989

Parity as a risk factor for cervical cancer.

In a case-control study of 759 invasive cervical cancer patients and 1,430 controls in Colombia, Costa Rica, Mexico, and Panama conducted during 1986-1987, an association with number of pregnancies persisted after adjustment for sexual and socioeconomic variables. Risks rose steadily to 5.1 (95% confidence interval 2.7-9.7) for those with 14 or more pregnancies and a relation of risk to multiparity was observed in all four study countries. Pregnancy associations appeared to relate to the number of live births rather than to miscarriages or abortions, with multiparity relations most pronounced among premenopausal women and oral contraceptive users. Human papillomaviruses types 16 and 18, as measured by filter in situ hybridization, were not significantly associated with number of births and did not explain the strong relation of parity to risk. Our results indicate the need for further consideration of reproductive factors on cervical cancer risk, with attention given to possible mechanisms of action, including hormonal factors and cervical trauma.

Adult↗
PubMed1989

Antithyroid and goitrogenic effects of millet: role of C-glycosylflavones.

Pearl millet [Pennisetum millet (L.) leeke] is the main source of food energy for the rural poor in many areas of the semiarid tropics. Epidemiological evidence suggests that millet may play a role in the genesis of endemic goiter in these areas, and sparse experimental data in rats support this suspicion. This study was undertaken to determine in vivo in rats and in vitro using porcine thyroid slices and a thyroid peroxidase (TPO) assay the goitrogenic and antithyroid effects of millet diets, extracts of millet, and certain pure compounds contained therein. For use in these studies, whole grain millet was progressively dehulled to yield successively four bran and four flour fractions in which direct analyses revealed progressively lower concentrations of C-glycosylflavones. In vivo feeding of bran fraction 1, that richest in C-glycosylflavones, led to a significant increase in thyroid weight and antithyroid effects. Feeding of bran fraction 2, the next richest in C-glycosylflavones, produced similar, but less marked, changes. In vitro studies of 125I metabolism using porcine thyroid slices indicated that extracts of bran fractions 1 and 2 were most potent, producing changes similar to those produced by methimazole (MMI). At a concentration of 60 mumol/L, glucosylvitexin, the major C-glycosylflavone present in millet, had effects comparable to those of 1 mumol/L MMI. Similarly, in studies of porcine TPO, extracts of bran fraction 1 caused pronounced (85%) inhibition of enzyme activity, and progressively less inhibition was induced by extracts of bran fractions 2, 3, and 4. Overall, the TPO-inhibiting activities of the various millet fractions closely correlated with their C-glycosylflavone concentrations. Three C-glycosylflavones present concentrations. Three C-glycosylflavones present in millet, glucosylvitexin, glycosylorientin, and vitexin, also inhibited TPO activity. Thus, in vivo and in vitro studies revealed that millet diets rich in C-glycosylflavones produce goitrogenic and antithyroid effects similar to those of certain other antithyroid agents and small doses of MMI. We conclude that in areas of iodine deficiency in which millet is a major component of the diet, its ingestion may contribute to the genesis of endemic goiter.

Animals↗
PubMed1989

Thyroid function in neonates from goitrous and nongoitrous iodine-sufficient areas.

We compared thyroid function between newborns from goitrous and nongoitrous localities in which iodine intake has been supplemented since 1955. Cord serum samples were analyzed in 185 infants born during a 9-month period (1986-1987) in 2 goitrous and 1 nongoitrous localities of western Colombia. Urinary iodine was determined in all mothers before delivery. No significant differences were found among neonates of the 3 localities (Kruskal-Wallis test) for the various thyroid hormone values, and all values were within the normal range, although there was a trend in distribution of TSH to higher values in both goiter areas. Thyroid autoantibodies (antithyroglobulin and antithyroid microsomal) were negative in all neonates, and iodine intake, as indicated by urinary iodine, was adequate and similar among the mothers of the 3 groups. Those newborn infants with serum TSH values higher than 20 mU/L were reexamined 5-7 months later. At this time, all infants had lower serum TSH values and their serum free T4 index and T3 values were normal. Gestational age, weight, and height at birth were normal and also equal among the neonates in the 3 localities. These results indicate that neonates from goitrous iodine-sufficient areas have thyroid function similar to that of infants born in nongoitrous areas equally supplemented with iodine, and therefore, they are not more at risk to develop congenital hypothyroidism.

Colombia↗
PubMed1988

Goitrogens.

A large number of agents in the environment and some medications are known to interfere with thyroid gland function, posing the danger of thyroid disease. Pollutants that cause goitre are known as environmental goitrogens which may cause the condition by acting directly on the thyroid gland but also indirectly by altering its regulatory mechanisms and the peripheral metabolism and excretion of thyroid hormones. However, the mechanism that induces the trophic changes leading to goitre formation, and in some instances with hypothyroidism, is not well understood. Antithyroid compounds may enter into the water, air and food exposure pathways, becoming an important environmental goitrogenic factor in man and other animals. Naturally-occurring and anthropogenic agents may act as goitrogens, as well as some drugs, which in the presence of dietary iodine deficiency may exaggerate the goitre and associated disorders. In iodine-sufficient areas, these compounds may be responsible for the development of some "sporadic' goitres or the persistence of the goitre endemia with its associated disorders. At present, medical or surgical treatments for the individual, but not measures for prevention and control at community level, are being applied in iodine-sufficient goitre areas.

Animals↗
PubMed1987

Case-control study of human papillomaviruses and cervical cancer in Latin America.

Human papillomavirus (HPV) types 16 and 18 have been implicated as risk factors for cervical dysplasia and neoplasia. However, most studies have been observational, uncontrolled and conducted in populations at low risk for invasive cancer. We report a pilot case-control study of incident invasive cervical cancer in Panama, Costa Rica and Bogota, Colombia. Between July and September 1985 we enrolled 46 consecutive newly diagnosed invasive cervical cancer cases and 51 age-matched control women. Subjects were interviewed and samples collected for HPV DNA assays. HPV infection was defined by a filter in situ DNA hybridization technique under non-stringent and stringent conditions against HPV-6/11, 16 and 18 DNA probes. More cases (91%) than controls (63%) had HPV DNA detected (non-stringent) and more cases than controls had HPV-16 or 18 DNA (67% vs. 43%, p = 0.02). Age at first intercourse was the most significant risk factor for HPV 16/18 infection in all subjects. Smoking was significantly associated with cervical cancer (52% of cases vs. 27% controls) but was not associated with HPV infection.

Adult↗
PubMed1984

The use of iodine as a thyroidal blocking agent in the event of a reactor accident. Report of the Environmental Hazards Committee of the American Thyroid Association.

In the event of a nuclear reactor accident, radioactive materials could be released into the environment: radioisotopes of iodine could constitute a major component of such a release. Upon such exposure, radioiodines could enter the body and accumulate in an unprotected thyroid gland where they would remain for varying periods of time. A number of methods have been proposed to protect those at risk of exposure. Administration of thyroid-blocking agents (such as potassium iodide) to exposed populations could be effective, but their use has raised a number of questions since there are considerable gaps in the scientific information available about the possible effects of low-level radiation from radioiodine. In addition, there are only limited data available about potential toxic side effects of potassium iodide distributed widely to large, unsupervised populations. Concern about these issues led the American Thyroid Association to appoint a committee of its members with special interest and competence in these areas to review the problems in detail and develop an advisory statement on the questions at issue for those to whom this matter might be of concern.

Accidents↗
PubMed1983

In vitro measurement of antithyroid compounds and environmental goitrogens.

A specific, sensitive, and reproducible in vitro assay for antithyroid compounds and environmental goitrogens has been used to investigate antithyroid activity (AA) in small samples of water supplying 15 localities in endemic and nonendemic goiter areas of western Colombia. A significant positive correlation was observed between goiter prevalence and AA in water collected from the pipelines of these localities. Samples at the water source showed only borderline significance. No significant correlation was observed in waters between AA and total hardness (ppm) or concentrations of Ca, Mg, sulfates, chlorides, silicates, nitrates, and iodine. AA was also demonstrated by this in vitro assay in well water previously shown experimentally to be goitrogenic and that supplied the endemic goiter district of Candelaria town in western Colombia. In contrast, water from the well supplying the area of lower endemicity was found to possess little AA. These results provide experimental support for epidemiological observations that demonstrate a relationship between the sources of drinking water and goiter prevalence rates, and are consistent with previous findings indicating that organic antithyroid compounds contaminate water supplies in areas where goiter persists despite adequate iodine supplementation.

Animals↗
PubMed1983

Defective thyroidal iodine concentration in protein-calorie malnutrition.

Although protein-calorie malnutrition (PCM) is known to result in various abnormalities of thyroid function, the exact relationship between the two is not clearly understood. Therefore, the thyroid function of 10 men, 13-55 yr of age, with severe PCM was studied in a clinical research ward before and 3-4 months after protein-calorie repletion. Before repletion, all subjects had low serum T4 (mean +/- SEM, 5.1 +/- 0.5 micrograms/dl) and T3 (74 +/- 6 ng/dl) concentrations. Eight subjects were chemically euthyroid, and their free T4 (1.5 +/- 0.1 ng/dl) and serum TSH (2.9 +/- 1.4 microU/ml) values were normal. Two subjects were chemically hypothyroid, with low free T4 values and high serum TSH values. After repletion, the 8 euthyroid subjects had significant increases in serum T4 (P less than 0.01) and T3 (P less than 0.005), but TSH did not change. Serum T4 and T3 were still lower (P less than 0.05-0.001) and TSH higher (P less than 0.01) than in 28 normal men of comparable age coming from the same area. After repletion, values remained unchanged in the 2 hypothyroid subjects, except for moderate increases in serum T3 and slight decreases in TSH. In all PCM subjects, values of thyroidal exchangeable iodine (23.1 +/- 7 vs. 42.9 +/- 8 mg; P less than 0.02), estimated thyroidal I per g wet wt (1.05 +/- 0.3 vs. 1.99 +/- 0.36 mg; P less than 0.02), and thyroidal iodide clearance (13.8 +/- 1.6 vs. 19.4 +/- 1.3 ml/min; P less than 0.002) were lower before repletion than after; the protein-bound 131I level (72 h; 0.27% vs. 0.08 dose/liter; P less than 0.05) was higher, but thyroid hormone secretion rates (200 +/- 49 vs. 153 +/- 25 micrograms/day) were not significantly different. Thyroid iodide clearance was lower even though plasma inorganic iodine (6.3 +/- vs. 12.5 +/- 3 micrograms/liter; P less than 0.05) and daily urinary iodine excretion (158 +/- 43 vs. 395 +/- 62 micrograms; P less than 0.01) were lower before than after repletion. In 2 PCM euthyroid subjects, baseline thyroid 131I uptake was lower before than after repletion, and the magnitude of the increase after TSH (10 U, im) stimulation was greater when the malnourished state improved. TSH increased concentrations of serum T4 and T3 both before and after protein repletion. After repletion, one hypothyroid patient failed to respond to TSH; the other had a small increase in 131I uptake but not in serum T4 or T3. The results indicate defective thyroid iodine concentration in human PCM, but adequate hormone secretion. This situation leads to depletion of thyroid iodine stores. This alteration, if extreme, might result in hypothyroidism. Adequate protein-calorie intake tends to reverse these abnormalities.

Adolescent↗
PubMed1983

Endemic goiter in western Colombia.

Goiter continues to occur in some areas of western Colombia despite iodine supplementation for 30 years. In 1973-1977, an average goiter prevalence of 15% (range 1-42%) still persisted among schoolchildren of 41 localities. Significant relationships were found between goiter prevalence and both the geological composition of watersheds and bacterial contamination of water supplies. Together, these associations account for 80% of the observed variation in goiter prevalence. The presence of sedimentary rocks rich in organic matter (coals, shales, etc.) was the best indicator of disease. The second best indicator, presence of K. pneumoniae in the water source, was associated with lower goiter prevalence but, as in other investigations, contamination of the pipeline system (households and schools) with gram-negative bacteria was associated with higher disease rates. Thus, epidemiological evidence indicates a cause-effect relationship between sources of drinking water and the persistence and development of goiter in this part of the world. Furthermore, identification of resorcinol, phthalate esters, and sulfur-bearing organic compounds, possibly aliphatic disulfides, in the water supplying the endemic goiter district of Candelaria town in western Colombia adds experimental support to this hypothesis. Resorcinol is derived from coal and humic substances, high molecular weight complex polymeric organic compounds present in sedimentary rocks, soils and water. Resorcinol is goitrogenic in man and experimental animals. Phthalate esters, also related to humic materials, undergo biodegradation by gram-negative bacteria with production of intermediate metabolites possessing antithyroid activity. Like phthalates and resorcinol, organic disulfides have also been identified as water contaminants in other parts of the world, and are known to be potent antithyroid compounds. The goitrogenic effect of organic and bacterial pollutants in water supplies is more pronounced in segments of the population with dietary iodine deficiency--as seen prior to the iodine prophylaxis program--and/or poor socio-economic conditions. Studies are underway to provide both insight into the biogeochemical cycle of water-borne goitrogens and knowledge essential to the development of rapid, inexpensive, and precise methods for detecting and quantifying the offending agents, as well as devising effective sanitation techniques for their inactivation and/or elimination. The impact of such measures will be determined on goiter prevalence and other parameters of health and nutrition of the communities under study.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1980

Goiter prevalence and bacterial contamination of water supplies.

Previous epidemiological studies have shown a significant statistical correlation (P < 0.005 to P < 0.0005) between goiter prevalence and rock types in the watersheds that supply 37 localities in Western Columbia. Bacterial contamination has also been implicated as a cause of endemic goiter. We, therefore, did bacteriological studies to incorporate this variable into the statistical model in 34 of the 37 localities previously surveyed. Samples of the water in the 34 localities were taken at the water source or intake of water supply and at the pipeline system in households and schools. Samples were collected in sterile bottles and cultured on several media for 48 h. The number of bacteria per ml was determined by Quebec's camera and the bacteria (E. coli, Bacillus sp., K. pneumoniae, Proteus sp., and Neisseria sp.) were identified according to conventional methods. Multiple regression analysis and the logistic regression model were used to analyze the data. Only two variables had significant relationships with goiter prevalence: K. pneumoniae in the water source (P < 0.01) is related to a lower prevalence and the overall concentration of bacteria in the pipeline system (P < 0.05) is related to a higher prevalence. Multiple regression analysis to compare the effects of bacteriological variables to those of geological variables indicating rock types showed sedimentary rocks in the watershed associated (P < 0.005) with higher goiter prevalence and an increased concentration of K. pneumoniae in the water source again associated (P < 0.025) with lower goiter prevalence. Bacterial concentration in the pipeline system was of marginal importance (0.05 < P < 0.10). Thus, the presence of sedimentary rocks was the best indicator of disease. A second best indicator was the concentration of K. pneumoniae in the water source. We hypothesize that the lower goiter prevalence associated with K. pneumoniae may be a natural example of biodegradation of the organic contaminants that produce goiter.

Bacillus↗
PubMed1979

The differential effect of thyrotropin on the electrical responses of thyroid cells in monolayer cultures of varying duration.

The acute effects of thyrotropin on the membrane potential of thyroid cells maintained in the presence or absence of thyrotropin (0.2 U/ml) in the culture medium was determined. Monolayer cultures were prepared from porcine thyroid glands and cultured for 4--17 days after which the culture medium was exchanged for a buffered salt solution for intracellular measurements of the membrane potential. Cells were serially impaled with a microelectrode, first in the absence and then in the presence of 10 mU/ml thyrotropin. Cells cultured for 4--9 days depolarized from --29.6 +/- 1.7 (mean +/- S.E.) to --19.3 +/- 1.3 mV within 10 min after acute addition of 10 mU/ml thyrotropin. From 11 to 17 days of culture, basal membrane potentials were lower and, in most instances, cell hyperpolarization occurred within 30 min in response to thyrotropin. There was no difference in the electrical response of cells maintained in culture with or without thyrotropin. However, cells cultured with thyrotropin formed follicle-like structures in contrast to the monolayer formation of cells cultured without thyrotropin. The changes in the basal and stimulated electrical responses occur within a time frame similar to that reported for changes in the biosynthetic capacity of thyroid cells in culture. The data further emphasize the possible regulatory role of the cell membrane in stimulus-secretion coupling in the thyroid.

Animals↗
PubMed1978

Geologic implications in the distribution of endemic goiter in Colombia, South America.

A survey of 37 communities supplied by stream water and receiving iodised salt for the last 10-20 years indicates that the presence of sedimentary rocks in the watersheds of streams more closely correlates with goiter prevalence than 12 other possible causative variables. These results support the hypothesis that sedimentary rocks rich in organic matter are the main source of water-borne goitrogens.

Child↗