[Tuberculosis in health personnel: importance of surveillance and control programs]. / Tuberculosis en trabajadores de la salud: importancia de los programas de vigilancia y control.

OBJECTIVE: To describe tuberculosis surveillance results among healthcare workers of a tertiary care center. MATERIAL AND METHODS: All medical records of workers from 1992-1998 were reviewed. Demographics, labor, medical history, previous testing, PPD, booster shots and follow-up were analyzed. Statistical analysis was performed with odds ratios, p-values, and 95% confidence intervals. Subgroup analysis were done with chi 2. Kaplan-Meier estimates were used to analyze times to conversion. RESULTS: Surveillance was done in 1617 workers (68% female and 32% male). Mean age was 26.9 +/- 7.6 (15-68) years. Job positions were 30.5% nurses, 14.6% residents and 14.1% interns. Place of origin was Mexico City in 65.8%. BCG vaccination was present in 71.6% and 15.1% had previous PPD. Admission PPD was positive in 39.6%, negative in 48.3% and 12.1% were lost to follow-up. On negatives, 483 booster shots were applied, and 49 additional positives were found. Follow-up was done in 231 workers, of which 100 (43.3%) converted. The mean time for conversion was 22.8 +/- 12.4 months. The conversion rate at twelve months was 20%. Fifty workers received/accepted isoniazid prophylaxis. CONCLUSIONS: A high percentage of workers were PPD-positive; booster shots allowed the detection of an additional 10%. A high conversion rate underscores the need to organize tuberculosis control programs in Mexico.

Generation of memory CD4+, CD8+, CD45RO+ and CD16- lymphocytes activated with IL-2, INF-gamma, and TNF-alpha with specific cytotoxicity against autologous cervical cancer cells in a mixed leukocyte-tumour cell culture.

Cytotoxic T lymphocytes (CTL) specific against autologous human cervical cancer cells were generated in vitro from peripheral blood leukocytes (PBL) from four patients with non-keratinized epidermoid carcinoma. For this purpose, these patients' PBL were co-cultured for 28 days either with IL-2 or a mixture of IL-2, IFN-gamma and TNF-alpha in the presence of autologous tumour cells (ATC). Our results showed that these CTL were highly cytotoxic for ATC, weakly cytotoxic for heterologous cervical cancer tumour cells, and not cytotoxic for carcinoma cell lines, normal cervix cells nor autologous PBL. Proliferation and cytotoxicity against ATC were greater when the PBL were activated with the three cytokines. These CTL had a CD4:CD8 ratio of 1:1, were CD16- and CD45RO+ and their killing activity was inhibited by antibodies against CD3, CD8 and MHC-class I but not by antibodies against CD4, CD16 or HLA-class II. The possibility of generating specific CTL in long term cultures for cervical cancer therapy is also discussed.

Testosterone alters duodenal calcium transport and longitudinal bone growth rate in parallel in the male rat.

Duodenal active calcium transport and longitudinal bone growth rate have been shown previously to be regulated in parallel by alteration of gonadal hormone status in sexually maturing female rats. The present study was designed to extend these observations to the sexually maturing male rat. Male rats were orchidectomized (ORX) and given Silastic implants containing either testosterone or estradiol at 6 weeks of age. At 9 weeks of age, duodenal active calcium transport was measured by the everted gut sac method and longitudinal bone growth rate was determined by tetracycline labeling. Decreases in body weight, longitudinal bone growth rate, duodenal calcium transport, and serum Ca and P were exhibited by ORX animals as compared with age-matched control animals. Testosterone administration to ORX animals resulted in an increase in body weight, longitudinal bone growth rate, duodenal calcium transport, and serum Ca and P as compared with ORX animals to a level not significantly different from that of age-matched control animals. Estradiol administration to ORX animals resulted in an additional decrease in body weight, although no significant effect on duodenal calcium transport, serum Ca, or P was noted as compared with ORX animals. There were no statistically significant alterations in the circulating levels of 1,25-dihydroxyvitamin D, parathyroid hormone, or osteocalcin in response to any of the experimental manipulations of gonadal status. These results indicate that, as in the female, gonadal hormone status affects intestinal calcium transport in sexually maturing male rats in parallel with changes in bone growth rate by mechanisms that are independent of circulating levels of 1,25-dihydroxyvitamin D.

Calcium metabolism and bone mineralization in female rats fed diets marginally sufficient in calcium: effects of increased dietary calcium intake.

Experiments were carried out to determine the ability of female rats with poorly mineralized skeletons to increase bone mineralization in response to increased dietary Ca consumption. We specifically addressed this question with regard to two different periods of the life cycle: the period of sexual maturation (6-9 weeks of age), and in animals that had attained adult rates of skeletal mineralization (100 days of age). We found that at both stages, increased dietary Ca consumption resulted in increased trabecular bone volume and total bone Ca. In the younger animals, it was found that dietary history influenced the disposition of bone mineral. Animals that were initially Ca-deprived exhibited increased trabecular bone and decreased cortical thickness compared to animals continuously fed 0.5% Ca. Ovariectomy of mature animals reduced but did not eliminate the response to increased Ca intake.

The relationship between long bone growth rate and duodenal calcium transport in female rats.

Studies were carried out to determine the relationship between long bone growth and duodenal calcium (Ca) transport in female rats and the regulation of these two parameters by ovarian hormones. Female rats were ovariectomized (ovx) at 6 weeks of age. Some animals were implanted with silastic implants containing either estradiol or progesterone at the time of ovx. Studies were carried out 3 weeks later when the rats were 9 weeks old. Ovx resulted in an increase in long bone growth rate and duodenal Ca transport without any alteration in circulating levels of parathyroid hormone or 1,25-dihydroxyvitamin D [1,25-(OH)2D]. Animals receiving estradiol exhibited decreased long bone growth rate and duodenal Ca transport relative to ovx animals. These animals were mildly hypercalcemic and had lower levels of 1,25-(OH)2D than ovx or intact animals. The results of these studies suggest that the effects of ovarian hormone status on duodenal Ca transport are more closely related to long bone growth rate than to circulating levels of 1,25-(OH)2D. Further studies are required to determine whether the two parameters are coregulated by some as-yet-unidentified factor or whether bone growth is able to emit some signal, directly or indirectly, to increase duodenal Ca transport.

The effect of low dietary calcium and calcium supplementation on calcium metabolism and bone in the immature, growing rat.

The data presented here were obtained from a series of experiments designed to determine 1) whether normal growth and bone development could be maintained in young, growing rats (3-9 weeks of age) on a diet containing 0.1% Ca, and 2) whether Ca presented in a bolus would be utilized as effectively as the same amount of Ca distributed throughout the diet. Weanling female rats were raised to 9 weeks of age on diets containing 0.4% P and either 0.5% or 0.1% Ca. One group of animals on the 0.1% Ca diet was given oral supplements of CaCO3 twice each day to supply the same amount of Ca consumed by age-matched animals on the 0.5% Ca diet. We found that animals consuming diet containing 0.1% Ca grew at the same rate as animals receiving 0.5% Ca, or 0.1% Ca + supplement for up to 9 weeks of age when the experiment was terminated. Measurement of femur length indicated that long bone length was the same for all animals. However, the 0.1% Ca group exhibited mild hypocalcemia (9.1 mg/dl vs 10.4 for controls), a 2.6-fold elevation in immunoreactive parathyroid hormone, and an increase of similar magnitude in circulating levels of 1,25-dihydroxyvitamin D. Bones from the 0.1% Ca group contained less than half as much Ca as bones from the 0.5% Ca group, and exhibited significant decreases in mid-shaft diaphyseal thickness, % trabecular volume of the distal metaphysis and breaking strength (torsion testing). These results suggest that while a diet containing 0.1% Ca is able to maintain normal growth, bone mineralization is compromised.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of ovariectomy on duodenal calcium transport in the rat: altered ability to adapt to low-calcium diet.

Studies were undertaken to determine whether ovariectomy (ovx) would alter the ability of female rats to adapt to low dietary Ca intake by exhibiting an in duodenal active Ca transport. Intact and ovx female rats were fed diets containing 1.5, 0.50, or 0.02% Ca prior to measuring active Ca transport using everted duodenal sacs in vitro. In some experiments, ovx animals were pair-fed to intact animals of the same age consuming the same diet. When ovx animals were allowed to eat ad lib, we found that both growth rate and duodenal active Ca transport increased relative to age-matched, intact controls. However, when growth of ovx animals was maintained at the control rate by pair-feeding, ovx per se did not affect intestinal active Ca transport. Ovx did not alter circulating levels of 1,25-dihydroxyvitamin D (1,25(OH)2D). We found that intact females responded to the low-Ca (0.02%) diet with increased circulating 1,25(OH)2D levels and increased intestinal active Ca transport. Ovx animals exhibited the same increase in circulating concentrations of 1,25(OH)2D in response to low-Ca diet, but did not demonstrate increased duodenal active Ca transport. When ovx animals consumed the diet ad lib, they became larger and exhibited higher Ca transport rates than intact animals fed the high-Ca diet, but there was no difference in Ca transport between ovx animals fed diets containing different Ca contents. The results of these experiments demonstrate that in female rats, the ability to adapt to altered dietary Ca intake is dependent on intact ovarian function and is not necessarily directly related to circulating concentrations of 1,25(OH)2D.

Developmental changes in duodenal calcium transport in female rats related to ovarian hormone status and growth rate.

Duodenal active calcium (Ca) transport is known to decrease with age in male rats. The present studies were undertaken to extend this observation to female rats, and to determine whether alterations in active Ca transport are related to sexual maturation in the female. Everted duodenal sacs from intact and ovariectomized (ovx) rats were used to measure duodenal active Ca transport. Female rats were raised from weaning, and Ca transport was measured at 2-week intervals until 12 weeks of age. Transport rates were found to be the highest from 4 to 6 weeks of age, and then to decline over the next 4-6 weeks. However, if females were ovx as weanlings, the age-related decline in Ca transport failed to occur. Ovariectomy of immature females also prevented the slowing of growth rate which normally accompanies sexual maturation in female rats. We therefore repeated the experiment, pair-feeding the ovx animal to intact controls to maintain normal growth rates. When growth was normalized in this manner, the Ca transport rate in ovx animals declined with age at the same rate as in intact animals. Since ovx of sexually mature rats has been reported to increase growth rate, we studied the relationship between duodenal Ca transport and growth rate in females ovx at 12 weeks of age and pair-fed to age-matched intact females. After 5 weeks, ovx was found to have resulted in an increase in both weight and duodenal active Ca transport relative to the intact animals. Ovariectomy did not alter circulating levels of 1,25-dihydroxyvitamin D.(ABSTRACT TRUNCATED AT 250 WORDS)

Enumeration of potentially pathogenic bacteria from sewage sludges.

To ascertain the health risks that may be posed by the land application of sewage sludges, a scheme was devised to determine the types and numbers of pathogenic and potentially pathogenic bacteria present in sludges. A processing treatment was adapted to sludge to give a homogenate which yielded the greatest numbers of viable bacteria. Conventional methods were successful in enumerating Klebsiella, Staphylococcus, gram-negative enteric bacteria, and commonly used indicator organisms. Modifications of conventional methods improved the enumeration of Salmonella, Mycobacterium sp., fluorescent Pseudomonas sp., and Clostridium perfringens. However, Shigella methodology yielded only one isolate. Utilizing the proposed scheme, the population densities of these organisms were estimated in three domestic wastewater sludges. In light of these results, the potential impact of land application of sewage sludges is discussed.