Background: Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by inflammatory lymphocytic infiltration of the salivary glands, leading to dryness of the mouth (xerostomia). It has been postulated that xerostomia is the preceding stage for the development of alterations in taste acuity (dysgeusia) in this type of patients. Objectives: To determine detection and recognition thresholds to the 4 basic tastes (sweet, salty, sour and bitter) in pSS patients and compare them to a control group. To determine if the long-term consumption of chile peppers and spicy Mexican diets had an effect on the taste perception and acuity of the pSS patients. Setting: This study was done in the Department of Food Science and Technology of the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ), a third-level hospital in Mexico City. Subjects: The patient group consisted of 21 Mexican females (mean±s.d., age: 53.1±9.8 y) diagnosed with pSS (time of duration of the disease, 8.6±6.6 y, median 7 y, range 1–25 y) who were recruited at the outpatient service of the Department of Immunology and Rheumatology of the INCMNSZ. The control group consisted of 20 healthy nonsmokers age-matched Mexican women (50.3±11.9 y) most of them personnel of the INCMNSZ, and some friends and nonblood relatives to the patients (sisters-in-law) who volunteered to participate in the study. Interventions: Detection and recognition thresholds were determined by the method of least noticeable differences on three occasions during three nonconsecutive days. Saliva production was determined by Saxon's test on two separate occasions. Results: Although saliva production was severely reduced in pSS patients (1.35±0.55 ml/2 min, P<0.001) compared to controls (6.26±2.41 ml/2 min), all subjects recognized the 4 basic tastes when these were tested at suprathreshold concentrations. The detection thresholds for the sweet, sour and bitter tastes were higher in pSS patients, as well as the recognition thresholds for the salty, sour and bitter tastes. A relationship between time of evolution of the disease and saliva production with individual thresholds could not be established. Conclusions: pSS patients exhibited different degrees of dysgeusia depending on the taste being studied, that is, they were mildly dysgeusic for the sweet and salty tastes and clearly dysgeusic for the sour and bitter tastes. Although both pSS patients and controls had consumed ‘typical Mexican diets’ their entire lives, our results showed that the consumption of chile peppers and spicy foods did not have any effect on the taste perception and acuity of the pSS patients.

Background: There is evidence that pyridoxine deficiency may alter the immune response. It is not known whether a deficiency of this vitamin is evident in subjects with primary Sjögren's syndrome (SS). Objective: We studied whether subjects with primary SS showed a biochemical deficiency of pyridoxine, and if it is associated with abnormal production of interleukin-2 from lymphocytes stimulated in vitro with phytohemagglutinin (PHA). Design: Two studies were conducted, (i) biochemical and nutritional assessments were performed in a cross-over study in subjects with primary SS, who were supplemented with 25 mg/day of pyridoxine or placebo for 3 months. After 1 month washout, they were supplemented for 3 months with placebo, (ii) patients with SS and matched controls received pyridoxine or placebo for 45 days, and a blood sample was obtained to study IL-2 production and expression in T-lymphocytes stimulated with PHA. Results: Subjects with primary SS showed limited dietary intake of pyridoxine and biochemical deficiency of this vitamin assessed through the activation coefficient of the erythrocyte aspartate aminotransferase. The biochemical deficiency did not affect production nor mRNA expression of IL-2 from T-lymphocytes stimulated in vitro with PHA compared with the control group. Supplementation of subjects with primary SS with 25 mg/day with pyridoxine for 45 days did not produce any significant change as compared to those patients supplemented with placebo. Conclusions: Subjects with primary SS showed biochemical deficiency of pyridoxine, possibly due to limited intake of this vitamin which was corrected by supplementation with pyridoxine. However, IL-2 production and mRNA expression from stimulated lymphocytes were unaffected by supplementation, probably because the deficiency was not severe enough to affect the immune system. Sponsorship: This work was supported by the National Council of Science and Technology (CONACYT), Mexico, grant no. 212226-5-0902PM.

BACKGROUND:Additional calcium is required during lactation, and several calcium regulatory factors are involved in calcium balance. In lactating rural women who have marginal nutrition and consume a high-fiber diet, negative calcium balance may be expected.OBJECTIVE:We evaluated calcium balance and its association with potential calcium regulatory factors in lactating, rural Mexican women who had marginal nutrition and consumed a high-fiber diet.DESIGN:This cross-sectional study included women at 1, 3, 6, and 12 mo of lactation (L1, L3, L6, and L12 groups) and women who had weaned their infants (W group). Age-matched, nonlactating women (NL group) were also included. Calcium balance and concentrations of calcium regulatory factors were determined. Correlation analysis was performed by using data from all of the lactating women.RESULTS:Calcium balance in the L1, L3, and L6 groups was negative and was significantly different (P < 0.05) from that in the W and NL groups. Serum parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH)(2)D] concentrations were significantly higher (P < 0.05) in the W group than in the L and NL groups. Calcium balance was positively associated with serum estradiol concentrations (r = 0.58, P < 0.05) and negatively associated with serum 1,25-(OH)(2)D concentrations (r = -0.52, P < 0.05). Breast-milk calcium concentrations correlated positively with serum PTH-related peptide (PTHrP) concentrations (r = 0.51, P < 0.05) and negatively with serum estradiol concentrations (r = -0.57, P < 0.05).CONCLUSIONS:Negative calcium balance was observed during lactation in rural Mexican women who consumed a high-fiber diet. Furthermore, the data suggest that the hormones estradiol and PTHrP are involved in the regulation of calcium balance and of the calcium content of milk during lactation.

Insulin-like growth factor I(IGF-I) stimulates renal and placental 1,25-dihydroxyvitamin D [1,25-(OH)(2)D] and is considered an important regulator of fetal growth. As 1,25-(OH)(2)D and birth weight are low in preeclampsia, this study was undertaken to determine whether circulating levels of IGF-I were associated with serum 1,25-(OH)(2)D concentrations in preeclamptic (PE group) and normotensive (NT group) pregnancies. Maternal and umbilical cord serum levels of IGF-I and 1,25-(OH)(2)D were significantly (P < 0.01) lower in the PE group than in the NT group. The concentrations of these two hormones correlated significantly in the umbilical cord (P < 0.05) and in the maternal (P < 0.001) compartments of the PE and NT groups, respectively. The amount of IGFBP-3 was 64% lower whereas that of IGFBP-1 was 2.9-fold higher in umbilical cord serum of the PE group compared with the NT group. In addition, maternal and umbilical cord serum IGF-I correlated significantly (P < 0.05) with weight and length at birth only in the PE group. In conclusion, the results of this study indicate that circulating IGF-I and 1,25-(OH)(2)D levels in both maternal and umbilical cord compartments are low in preeclampsia. Furthermore, this study suggests a differential regulatory effect of IGF-I on 1,25-(OH)(2)D synthesis and fetal growth depending on the presence or absence of preeclampsia.

Metabolizable energy from the habitual diet was measured in lactating women from a Mexican rural community. Food intake was estimated in 12 women, age 25 ± 5 y, 2–6 m postpartum, body weight 48 ± 4 kg and height 147 ± 4 cm. Rural diet was predominantly from vegetable sources based on maize (tortillas), beans, tomato, onion and chili. The group was studied in free conditions with their habitual diet intake and in balance conditions consuming a controlled diet similar to their rural diet. Four women participated in a second balance with a modified diet, low in fiber and higher in protein and fat content in comparison with the habitual rural diet. Metabolizable energy was lower (P<0.05) by an average of 744 kJ/d in the rural diet than the modified diet. Apparent digestibility of energy increased from 82% and 87% with the free and controlled rural diets, respectively, to 93.4% with the modified diet. Digestibility for nitrogen and fat in the lactating women consuming the modified diet was higher (>22%) than with the rural diet. Metabolizable energy from the rural diet by the lactating women group was lower (8.1 MJ/d) than the energy recommended allowances during lactation. Nutrient digestibility from the rural diet was similar to those found in populations with intake of predominantly vegetable diets with high dietary fiber content.

The aim of the present study was to assess the effects of insulin-like growth factor I (IGF-I) upon the synthesis of 1, 25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] by human placenta trophoblasts in culture. Cytotrophoblastic cells obtained from normal term human placentae were cultured in Dulbecco's modified Eagle's medium with HEPES and glucose (DMEM-HG) during 72 h and further incubated in serum-free DMEM-F12 in the presence of IGF-I prior to the addition of [(3)H]-25-(OH)D(3) used as a precursor. The results showed that 2 h preincubation time with IGF-I was required for maximal production of [(3)H]-1,25-(OH)(2)D(3). Cultures in the presence of increasing concentrations of IGF-I (0-6.5 nmol/l), added 2 h before incubation with the labelled substrate, resulted in a dose-dependent response increment of [(3)H]-1,25-(OH)(2)D(3) production with a maximal conversion rate at the dose of 2.6 nmol/l. Higher doses of IGF-I did not result in further stimulatory effects. Co-incubations in the presence of cycloheximide significantly (P < 0. 0001) inhibited the IGF-I-mediated effects upon [(3)H]-1, 25-(OH)(2)D(3) production. Identity of putative [(3)H]-1, 25-(OH)(2)D(3) produced by human placenta was confirmed by spectral and receptor binding analysis. These results demonstrate the ability of cultured human syncytiotrophoblast cells to convert 25-(OH)D(3) to 1,25-(OH)(2)D(3) and suggest a local protein-dependent regulatory effect of IGF-I upon this biotransformation.

A high protein concentration in the diet induces the gene expression of several amino acid degrading enzymes such as histidase (Hal) in rats. It is important to understand whether the amino acid pattern of the dietary protein affects the gene expression of these enzymes. The purpose of the present work was to study the effect of a histidine-imbalanced diet on the activity and mRNA concentration of rat hepatic histidase. Seven groups of six rats were fed one of the following diets: 1) 6% casein (basal), 2) 20% casein, 3) 35% casein, 4) an imbalance diet containing 6% casein plus a mixture of indispensable amino acids (IAA) equivalent to a 20% casein diet without histidine (I-20), 5) 6% casein plus a mixture of IAA equivalent to a 35% casein diet without histidine (I-35), 6) a corrected diet containing 6% casein plus IAA including histidine equivalent to a 20% casein diet, 7) a corrected diet containing 6% casein plus IAA including histidine equivalent to a 35% casein diet. Serum histidine concentration was inversely proportional to the protein content of the diet, and it was significantly higher in rats fed the corrected diets compared to their respective imbalanced diet groups. Hal activity increased as the protein content of the diet increased. Greater histidine imbalance resulted in lower food intake and higher Hal activity. Rats fed histidine-corrected diets had lower activity than their respective imbalanced groups. Differences in Hal activity were associated with differences in the concentration of Hal mRNA. These results indicate that rats fed a histidine-imbalanced diet exhibit reduced food intake and weight gain and increased Hal gene expression as a consequence of an increased amino acid catabolism.

The effect of glucagon and hydrocortisone was investigated to understand the mechanism of induction of hepatic histidase gene. In this study, glucagon (0.6 mg/100 g body wt/d) was injected to rats fed 10% casein diet. After 3 h of the last injection, histidase activity and amount of enzyme were induced by 3 fold and histidase mRNA concentration by 6 fold. Injection of hydrocortisone (2 mg/100 g body wt/d) increased 100% histidase activity and mRNA concentration and by 150% the amount of enzyme after 3 h of the last injection. These results indicate that glucagon is a better inductor of histidase gene expression than hydrocortisone. Another purpose of the study was to evaluate if a protein-free/high carbohydrate diet could reverse the induction of Hal expression produced by a high protein diet. Hal activity, amount of enzyme and mRNA concentration was repressed by 68, 88 and 95% respectively by a protein-free/high carbohydrate diet. Injection of glucagon reversed partially the effect of a high carbohydrate diet, however, injection of hydrocortisone under the concentration used in these experiments did not reverse the effect of a high carbohydrate diet. These results support the evidence that hepatic histidase gene expression is probably regulated transcriptionally by hormones.

We studied the effect of nutritional rehabilitation with a 6, 18 or 50% casein diet in undernourished rats on histidase (Hal) expression. Undernutrition was induced by feeding rats a 0.5% casein diet for 5 wk, Over this period, growth, serum total proteins and insulin-like growth factor-I (IGF-I) levels were significantly lower than those of rats that freely consumed an 18% casein diet. During this period, undernutrition also significantly reduced Hal activity and Hal-mRNA concentration. Nutritional rehabilitation for 21 d with a 6% casein diet did not change any of these variables, Nutritional rehabilitation with an 18 or 50% casein diet for 1 d initiated the restoration of Hal activity and mRNA concentration. After 10 d of consuming 18 or 50% casein diets, Hat activity was 5- and 14-fold, and mRNA concentration was 8,5- and 23-fold higher, respectively, than in the protein-undernourished group (PU). During this period, body weight, total serum proteins and IGF-I levels were also significantly (P < 0.05) higher than those of the PU group, At the end of 21 d of rehabilitation with an 18 or 50% casein diet, Hal activity was 14- and 31-fold higher and Hat mRNA concentration was 10- and 24-fold higher, respectively, than in the PU group. In conclusion, our data showed that rehabilitation of undernourished rats with a 6% casein diet was not sufficient to re-establish growth indicators, Hal activity or gene expression, and that nutritional rehabilitation with an 18 or 50% casein diet effectively re-established body weight, biochemical variables and the capacity of histidase gene expression to eliminate the excess of protein.

The effect of dietary protein on the expression of histidase (Hal) was investigated to understand the mechanism of induction of histidase by a high protein diet. In this study, we examined the following: 1) the effect of 0, 6, 18, 35 and 50% casein diets on hepatic and epidermal Hal activity, amount of the enzyme and Hal-mRNA; 2) the effect of a high histidine diet (1.25%) on Hal expression; 3) the response of Hal expression in rats fed a 10% casein diet and injected with glucagon (0.6 mg /(100 g body wt⋅d); and 4) the half-lives of the enzyme and Hal-mRNA in rats fed an 80% casein diet for 7 d followed by a protein-free diet. Hal activity increased as the protein content in the diet increased (r = 0.986, P < 0.001) and was associated with a significant increase in Vmax without a change in Km. The dietary regulation was liver specific because skin Hal was unresponsive. Increments in hepatic Hal activity were accompanied by concomitant significant increases in the amount of histidase and its mRNA. The response was more pronounced in rats fed diets containing >18% casein. Rats fed a 12% casein diet containing 1.25% histidine did not have different Hal activity and mRNA levels compared with rats fed a 12% casein diet, indicating that Hal expression is not modified by its substrate. Injection of glucagon into rats fed the 10% casein diet increased Hal activity threefold and Hal- mRNA expression fivefold compared with uninjected rats fed the same diet. The apparent half-life of hepatic histidase in protein-depleted rats previously fed an 80% casein diet was 2.8 d, whereas the half-life of Hal-mRNA was 17 h. In summary, these data support the hypothesis that Hal expression is regulated by dietary protein at the pretranslational level in rat liver, and that glucagon is one of the hormones involved in the induction of Hal.

The purpose of the study was to measure the variation in concentrations of plasma neutral and basic amino acids during the day in subjects fed two Mexican model rural diets, one containing 55% (R55) and the other 70% (R70) of energy as carbohydrates, and two model urban diets with the same two proportions of carbohydrates (U55 and U70). The R55 and R70 diets contained 1.35- and 1.69-fold more fiber than the U55 and U70 diets, respectively. Eight female volunteers were adapted to each of the four diets for 3 d before the day of blood sampling. Protein and energy intakes were adjusted to each subject for a consumption of 1 g protein/kg body wt and 150.7 kJ/kg body wt. Blood samples were withdrawn at 0700, 0930, 1100, 1500, 1900, 2300, and 0300. Only plasma concentrations of alanine changed during the day, dropping significantly (P<0.05) at 2300 and 0300 with the U70 diet. Urban diets produced significantly higher plasma isoleucine and valine values than did the rural diets at some sampling times. Plasma phenylalanine was significantly higher with the U70 diet at 2300 than with the other three diets. Alanine plasma concentrations were significantly higher with the U55 diet at 1900 and significantly lower with the R55 diet at 0930 with respect to the other diets. Lysine was significantly higher at 0700 with the U70 diet than with the other three diets. No other significant changes were observed. These results show the stability of the plasma amino acid profile despite the consumption of different diets in physiologic proportions. Possibly, some of the changes observed in the plasma amino acids can be explained by the high proportion of dietary fiber in the Mexican rural diets.

The effect of dietary protein concentrations on the hepatic expression of phenylalanine hydroxylase (PAH) and tyrosine aminotransferase (TAT) mRNA concentrations was studied in rats adapted to consume diets (18 or 50% casein) in a restricted schedule of 7 h (0900 to 1600) for 5 days. After 6 hours of feeding, TAT mRNA concentrations of rats adapted to 18% casein diet and fed acutely 6, 18 and 50% casein diet were 0.15, 0.84 and 5.08 fold respectively higher than mRNA concentrations of rats before feeding. After 17 hours of fasting, TAT mRNA concentrations of rats previously fed 6, 18 or 50% casein diet were -0.45, 1.76 and 9.11 fold respectively higher than mRNA concentrations of rats before they were fed. PAH mRNA concentrations showed a similar pattern. There was a -0.68, 1.63 and 2.5 fold rise of PAH mRNA concentrations in rats fed 6,18 and 50% casein diet during the feeding period, and -0.86, 2.32 and 9.33 fold rise after 17 hours of fasting. TAT and PAH mRNA concentrations of rats adapted to consume 50% casein diet and then changed to 6% or kept on the 50% casein diet showed a maximum peak 6 hours after the rats began to consume the diet; however, they decreased 5 hours after fasting. These results suggest that increasing concentrations of protein in the diet were able to increase the concentration of TAT and PAH mRNA, possibly in order to eliminate the excess of amino acids consumed. The concentration of TAT and PAH mRNA depended more on the protein content of the diet to which the rats were previously adapted.

Nutrients can regulate, directly or indirectly, the pathway of expression of genes coding for enzymes involved in metabolic pathways related to the utilization of carbohydrates, lipids and amino acids. On the other hand, nutrients such as carbohydrates, lipids or amino acids can generate an specific hormonal state in the organism, and hormones are the mediators throughout which some genes are activated. The objective of the present review is to show some specific examples of dietary and hormonal regulation of enzyme genes involved in the metabolism of carbohydrates (phosphoenol pyruvate carboxykinase), lipids (malic enzyme) and amino acids (serine dehydratase).

In order to assess the nutritional status of riboflavin and pyridoxine during pregnancy, 24 Mexican women were studied during the second trimester and 17 during the third trimester of gestation. The biochemical evaluation of the riboflavin and pyridoxine status was performed by measuring the activation coefficients (AC) of the erythrocyte glutathione reductase (eGR) and aspartate aminotransferase (eAAT), respectively. Dietary protein, riboflavin, thiamin, and calcium intake decreased significantly in the last trimester of gestation. The women presented biochemical deficiency of pyridoxine in the second and third trimester of pregnancy, but they developed biochemical deficiency of riboflavin and pyridoxine deficiency. None showed clinical signs of vitamin deficiency. No significant correlation was found between individual serum concentrations of estradiol or progesterone and eGR-AC or eAAT-AC in both trimesters of pregnancy. Six newborns studied showed normal eGR-AC and eAAT-AC.

Common beans (Phaseolus vulgaris) constitute a staple food for most of the World’s population. Nevertheless, it has been known for a long time that common beans contain a wide variety of substances which may be considered as “anti-nutritional”, unless they are properly inactivated or destroyed.1–3 Among substances that are inactivated by the cooking process are the lectins, a especial type of proteins that display sugar-binding properties.4–6

A critical analysis was conducted in 39 publications on the prevalence of trace mineral deficiencies in Mexico, published since 1950. It can be concluded that: a) Iron deficiency is the most prevalent nutrient deficiency in Mexico. It occurs in 10 to 70% of the population depending on the region of the country. Rural areas in the southern and south-eastern regions are more drastically affected studies. This deficiency occurs even though iron intake in most studies is higher than recommended. b) Clinical signs of iodine deficiency have been reported in some mountainous regions of the country. These studies were carried out about 30 years ago, so the potential existence of iodine deficiency in these and other regions requires further study. c) There is some evidence of marginal zinc deficiency in some population groups. The magnitude of this deficiency, and the existence of other mineral deficiencies and their consequences for the health and function of the Mexican population, require further investigation.

We carried out a review of the studies related to vitamin deficiencies in the Mexican population published since 1950. Forty four studies were published from which we can conclude that: a) dietary intake data suggest that ascorbic acid, riboflavin and retinol intake are deficient: reported intakes were 40-70%, 35-64% and 20-72% of the recommended daily amounts respectively; niacin intake was also deficient in some studies; b) about 10% of Mexican children in rural areas had deficient values of plasma retinol (<100 ng/ml) and about 25 to 30% had low values (100-200 ng/ml); this prevalence is reduced in children with a higher socioeconomic level; c) some studies were found that show the existence of marginal deficiencies of vitamin E, riboflavin and vitamin B-12 in apparently healthy populations. Further studies are required to identify the magnitude of these and perhaps other vitamin deficiencies and their potential effects on the health and function of the Mexican population.

OBJECTIVETo assess whether the circulating levels of insulin-like growth factor I (IGF-I) are lower in preeclamptic than in normotensive pregnant women and whether serum concentrations of IGF-I are associated with those of 1,25 dihydroxyvitamin D (1,25-(OH)2D).STUDY DESIGNThe study was cross-sectional and was done at 26.7 to 39.7 weeks of pregnancy. The results obtained from preeclamptic women were compared with those obtained from normotensive pregnant women with the same gestational age (control group).SETTINGAll the volunteers were patients attending the General Hospital of Mexico City and all laboratory measurements were done at the National Institute of Nutrition Salvador Zubiran, Mexico City.SUBJECTSThe study included 26 preeclamptic women and 26 normotensive pregnant women. All participated voluntarily and signed an informed consent.PROCEDUREThe following measurements were done: serum concentrations of IGF-I, 1,25-(OH)2D, intact parathyroid hormone (PTH), inorganic phosphorus, creatinine, and total and ionic calcium and magnesium. Also urinary calcium and creatinine clearance were measured and dietary and anthropometric data were obtained. All determinations were done blindly. Comparisons between groups were done using the Mann-Whitney U-test. Associations between variables were tested using the Spearman rank correlation and stepwise regression.RESULTSSerum IGF-I levels were 26.1 +/- 10.2 nmol/L (mean +/- SD) in the preeclamptic group and 40.9 +/- 14.3 in the normotensive group (p = 0.0003); serum 1,25-(OH)2D levels were 43.6 +/- 8.2 pg/mL in the preeclamptic group and 52.1 +/- 10.2 in the normotensive group (p = 0.005). Serum intact PTH was similar in both groups. Serum levels of IGF-I, 1,25-(OH)2D, and intact PTH correlated significantly in the control group. In the preeclamptic group correlation was found only between IGF-I and 1,25-(OH)2D.CONCLUSIONSOur study brings out two interesting observations. First, that serum IGF-I levels were significantly lower in preeclamptic than in control pregnant women; and second, the existence of a significant correlation between serum IGF-I and 1,25-(OH)2D concentrations in both preeclamptic and normotensive pregnant women.

The in vitro synthesis of 3H1,25(OH)2D3 and 3H24,25-(OH)2D3 in different maternal (kidney and spleen), placental (maternal and fetal sides) and fetal (kidney, intestine, liver and skeleton) tissues and the relative contribution of each of these organs to total production was studied in the last six days of gestation in rats. On day 16, synthesis of both metabolites was higher in fetal tissues than in maternal kidney, and decreased as gestation advanced. On day 16, placental contribution represented more than 50% of the total production of 3H1,25(OH)2D3, while the maternal kidneys and the fetal tissues contributed only 16% and 26%, respectively. On day 18, the synthesis of 3H1,25(OH)2D3 by maternal placenta and fetal tissues was significantly reduced in comparison with that observed on day 16. Between days 16 and 19, the plasma concentrations of 1,25(OH)2D in mothers and fetuses were associated with the magnitude of its in vitro production. Starting on day 19, however, the in vitro production remained at the same level while the plasma concentration increased, suggesting lower utilization or lower catabolism of this metabolite. Similarly, the total synthesis of 3H24,25(OH)2D3 decreased on day 19. Between days 16 and 18, a higher synthesis of 3H24,25(OH)2D3 corresponded with lower plasma concentration of this metabolite suggesting greater utilization. In contrast, between days 19 and 21, the in vitro synthesis and plasma concentration of 24,25(OH)2D increased in parallel fashion. In summary we report the following findings: a) inhibition of the in vitro synthesis of 3H1,25(OH)2D3 and 3H24,25(OH)2D3 on day 19 of gestation in the rat; b) the contribution of each of the different maternal, placental and fetal tissues to the total synthesis of these metabolites in the last six days of gestation; and c) a parallelism between in vitro production and plasma concentration of both metabolites.

The effect of estradiol (E2) and progesterone (P4) on the IgA system, both at the systemic and at the mucosal level, was studied in 10 healthy young adult Mexican women during two consecutive menstrual cycles (MC); the control group consisted of five young adult Mexican men. Eight matched samples of blood and parotid saliva were obtained, in which serum E2, P4, and IgA were quantified. Parotid saliva was obtained with Curby's device and sIgA was quantified by an ELISA method. The MC was divided into follicular phase (FP, days 1 to 16) and luteal phase (LP, days 17 to 30). Serum IgA showed slight fluctuations along the period of study, but they were not different between women and men. Irrespective of the phase of the MC, salivary sIgA was higher in women than in men (P<0.01); sIgA was slightly but not significantly higher in the FP, as compared to the LP. The comparison of phases in each individual woman showed significantly higher levels in the FP (P<0.01). The profile of sIgA in saliva observed in women resembled the pattern of serum E2 (r = 0.859, P<0.05), suggesting a possible relation of E2 in the secretion of sIgA by the parotid gland.