Leaf and Fruit Methanolic Extracts of Azadirachta indica Exhibit Antifertility Activity on Rats' Sperm Quality and Testicular Histology.

BACKGROUND: The world's population is still growing, having an impact on the environment and the economic growth of developing countries; so that, there is a particular interest in the development of new fertility control methods, focused on male contraception. OBJECTIVE: The objective of this study was to evaluate the effect of methanolic extracts of leaf and fruit of Azadirachta indica on sperm quality and testicular histology of Long Evans rats. METHODS: Antifertility effects of a methanolic leaf and fruit extracts of A. indica on 24 male rats were investigated. The animals were randomly divided into two control groups and four treatment groups (n=4). Doses of the leaf and fruit extract were given at concentrations of 100 and 200 µg mL-1. RESULTS: A significant decrease in the viability of sperm cells was observed. The leaf extract at a concentration of 200 µg mL-1 inhibited cell viability compared to the negative control (p< 0.001). The percentage of abnormal cells in leaf extract was shown in 100 and 200 µg mL-1, the conditions at which a higher percentage of morphological irregularities of observed (15% and 16% respectively). The results show that there was cellular detachment in the seminiferous epithelium in the experimental groups treated with methanolic extracts. Sperm death was observed without decreasing the number of sperm. CONCLUSION: The methanolic extracts of Azadirachta indica have a modulating effect on the spermatogenesis of experimental rats through sperm morphological alterations.

Prevalence of eosinophilic esophagitis: A multicenter study on a pediatric population evaluated at thirty-six Latin American gastroenterology centers. / Prevalencia de esofagitis eosinofílica: estudio multicéntrico en población pediátrica evaluada en 36 centros de gastroenterología de América Latina.

INTRODUCTION AND OBJECTIVE: Eosinophilic esophagitis is a chronic, immune-mediated disease described in case series and publications worldwide. Over the past twenty years, the authors of different studies have attempted to evaluate its incidence and prevalence. The objetive of the present study was to estimate the prevalence of eosinophilic esophagitis in a group of children seen at 36 pediatric gastroenterology centers in ten Latin American countries. MATERIALS AND METHODS: A multicenter, observational, and cross-sectional study was conducted that estimated the period prevalence of eosinophilic esophagitis in children seen at outpatient consultation and that underwent diagnostic upper gastrointestinal endoscopy for any indication at 36 centers in 10 Latin American countries, within a 3-month time frame. RESULTS: Between April and June 2016, 108 cases of eosinophilic esophagitis were evaluated. Likewise, an average of 29,253 outpatient consultations and 4,152 diagnostic upper gastrointestinal endoscopies were carried out at the 36 participating centers. The period prevalence of eosinophilic esophagitis in the population studied (n=29,253) was 3.69 cases×1,000 (95% CI: 3.04 to 4.44), and among the children that underwent routine upper gastrointestinal endoscopy (n=4,152), it was 26x1,000 (95% CI: 22.6 to 29.4). CONCLUSIONS: The general period prevalence of eosinophilic esophagitis in a group of children evaluated at 36 Latin American pediatric gastroenterology centers was 3.69×1,000, and in the children that underwent endoscopy, it was 26×1,000. There was important prevalence variability between the participating countries and centers. The present analysis is the first study conducted on the prevalence of pediatric eosinophilic esophagitis in Latin America.

Induction of apoptosis in human breast cancer cells by tocopherols and tocotrienols.

The apoptosis-inducing properties of RRR-alpha-, beta-, gamma-, and delta-tocopherols, alpha-, gamma-, and delta-tocotrienols, RRR-alpha-tocopheryl acetate (vitamin E acetate), and RRR-alpha-tocopheryl succinate (vitamin E succinate) were investigated in estrogen-responsive MCF7 and estrogen-nonresponsive MDA-MB-435 human breast cancer cell lines in culture. Apoptosis was characterized by two criteria: 1) morphology of 4,6-diamidino-2-phenylindole-stained cells and oligonucleosomal DNA laddering. Vitamin E succinate, a known inducer of apoptosis in several cell lines, including human breast cancer cells, served as a positive control. The estrogen-responsive MCF7 cells were more susceptible than the estrogen-nonresponsive MDA-MB-435 cells, with concentrations for half-maximal response for tocotrienols (alpha, gamma, and delta) and RRR-delta-tocopherol of 14, 15, 7, and 97 micrograms/ml, respectively. The tocotrienols (alpha, gamma, and delta) and RRR-delta-tocopherol induced MDA-MB-435 cells to undergo apoptosis, with concentrations for half-maximal response of 176, 28, 13, and 145 micrograms/ml, respectively. With the exception of RRR-delta-tocopherol, the tocopherols (alpha, beta, and gamma) and the acetate derivative of RRR-alpha-tocopherol (RRR-alpha-tocopheryl acetate) were ineffective in induction of apoptosis in both cell lines when tested within the range of their solubility, i.e., 10-200 micrograms/ml. In summary, these studies demonstrate that naturally occurring tocotrienols and RRR-delta-tocopherol are effective apoptotic inducers for human breast cancer cells.

RRR-alpha-tocopheryl succinate induction of prolonged activation of c-jun amino-terminal kinase and c-jun during induction of apoptosis in human MDA-MB-435 breast cancer cells.

We have demonstrated that RRR-alpha-tocopheryl succinate (10 microg/mL vitamin E succinate (VES) treatment of estrogen receptor-negative MDA-MB-435 human breast cancer cells induces 9, 19, 51, and 72% apoptotic cells on days 1-4, respectively, after treatment, which involves transforming growth factor-beta signaling. Here, we show that VES-triggered apoptosis of MDA-MB-435 cells induced prolonged elevated expression of c-jun mRNA and protein (neither of which was caused by major increases in stability) and also induced enhanced activator protein-1 (AP-1) binding to the consensus DNA oligomer. Furthermore, VES treatments resulted in increased AP-1 transactivation activity, as measured with an AP-1 promoter/luciferase reporter construct and by the measurement of increased mRNA expression of the AP-1-dependent endogenous gene collagenase. Evidence of VES-induced involvement of the c-jun amino-terminal kinase in these AP-1-dependent events was suggested by data showing prolonged activity of this kinase, as measured by a kinase assay using glutathione S-transferase-c-jun as the substrate. The c-jun-dependent transcriptional activity was verified by cotransfection of a chimeric transcription factor having a galactose 4 DNA-binding domain coupled with the transactivation domain of c-jun plus the reporter plasmid 5X GAL4-luciferase. MDA-MB-435 cells infected with an adenovirus expression vector containing the TAM-67 sequence for dominant/negative-acting mutant c-jun or transiently transfected with c-jun antisense exhibited a 50-77% reduction in VES-mediated apoptosis as compared with control adenovirus-infected or control sense oligomer-transfected cells.

Setting generalization of question-asking by children with autism.

We examined whether motivational procedures incorporated into teaching question-asking to children with autism, who lack verbal initiations, would result in generalization without additional teaching, prompting, or reinforcement in other settings. Specifically, we assessed whether such children could learn to use questions and whether the spontaneous use of question-asking would generalize across stimuli, settings, and people. All children learned to use questions in relation to items they had previously been unable to label and demonstrated generalization of spontaneous question-asking to new items and to their home environments with their mothers, with concomitant gains in expressive vocabulary. Results were discussed in terms of teaching response strategies, such as question-asking, to promote spontaneous child-initiated social interactions and expressive language development.

Preweaning growth traits for Senepol, Hereford, and reciprocal crossbred calves and feedlot performance and carcass characteristics of steers.

We conducted a multiyear study in two phases to determine preweaning performance traits of Senepol (S x S), Hereford (H x H), and reciprocal (S x H and H x S) F1 crossbred calves and feedlot performance and carcass characteristics of steers. In Phase I, from 1985 to 1989, data from S x S (n = 194), H x H (n = 383), and S x H (n = 120) calves were used. Numbers of S x S cows were increased during Phase I so that data from H x S (n = 74) calves could be included in Phase II (1990 to 1992) in addition to S x S (n = 118), H x H (n = 130), and S x H (n = 56) calves. Also during Phase II, feedlot performance and carcass characteristics were determined for S x S (n = 30), H x H (n = 26), H x S (n = 36), and S x H (n = 26) steers. In Phase I, S x S calves had heavier (P < .01) birth weights and heavier (P < .01) 205-d adjusted weaning weights than H x H calves. Birth weights of S x H calves were heavier (P < .01) than the mean of the purebred calves, but 205-d adjusted weaning weights did not differ (P > .10). In phase II, direct heterosis was 3.5% for birth weight (P < .05) and 5.1% for 205-d adjusted weaning weight (P < .01). Senepol maternal breed effects were 1.9 kg for birth weight (P < .10) and 37.9 kg for 205-d adjusted weaning weight (P < .01). Levels of direct heterosis, Senepol maternal breed effects, and Hereford direct breed effects were significant for most feedlot performance traits of steer calves that were fed to a common end point. Breeds did not differ (P > .10) for USDA yield and quality grades, and direct heterosis was not significant for Warner-Bratzler shear force. These results demonstrate significant levels of heterosis in preweaning performance between S x S and H x H calves and in feedlot performance of steers. Levels of heterosis were smaller and nonsignificant for most carcass traits including meat tenderness, which did not differ between S x S and H x H steers in this study.

Effect of rotational vs continuous intensive stocking of bahiagrass on performance of Angus cows and calves and interaction with sire type on gastrointestinal nematode burden.

Performance of Angus cows and calves was compared between two methods of bahiagrass (Paspalum notatum Flügge) grazing management, rotational stocking (ROT) and continuous intensive stocking (CIS), where stocking rate was varied by adjusting available pasture area as forage growth rate changed during the growing season. Effects of sire type (low [LO] vs high [HI] EPD for nematode egg shedding rate [EPG]) also were studied. Data were analyzed for two complete cycles of calf production from breeding through weaning. There was no effect of pasture grazing management method on cow BW, cow body condition score, adjusted 205-d calf weaning weight, and preweaning calf ADG. Five genera of nematodes (Ostertagia, Haemonchus, Trichostrongylus, Cooperia, and Oesophagostomum) were recovered from calves removed and killed at times throughout the grazing season. Mean nematode numbers recovered increased (P < .05) for all species as the grazing season progressed from spring to fall, consistent with results on EPG (P < .001). Effect of sire type on EPG was not significant; however, sire type did affect mean EPG (P < .05) from a subset of calves placed in drylot after weaning and sampled for three consecutive days. Sire type affected IgG1 titer to H. placei (LO = .50 +/- .012, HI = .45 +/- .011) and IgA titer to O. radiatum (LO = .28 +/- .006, HI = .26 +/- .005), and there was a sire type x pasture grazing method interaction on IgG1 titer to H. placei (LO-ROT = .49 +/- .016, HI-ROT = .49 +/- .017, LO-CIS = .50 +/- .017, HI-CIS = .41 +/- .014). Increased anti-parasite antibody titers in progeny of sires with EPD for low nematode egg shedding rates may reflect increased host resistance to these parasites.

Involvement of activator protein-1 (AP-1) in induction of apoptosis by vitamin E succinate in human breast cancer cells.

The purpose of this study was to document induction of apoptosis by vitamin E succinate (VES; RRR-alpha-tocopheryl succinate) in human breast cancer cells in culture and to characterize potential c-jun involvement. VES at 18.8 microM (10 micrograms/mL) induced DNA synthesis arrest, reduced total cell numbers, and induced apoptosis in estrogen receptor-positive and estrogen-responsive MCF-7 human breast cancer cells. VES at 10 micrograms/mL induced apoptosis in greater than 60% of cells within 3 d of treatment. Apoptosis was documented by detection of fragmented or condensed nuclei in 4',6-diamindino-2-phenylindole-stained cells, detection of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeled DNA, and DNA laddering. Analyses of mRNA and protein levels of candidate molecules involved in apoptosis showed that MCF-7 cells treated with VES exhibited elevated and persistent expression of c-jun. MCF-7 cells stably transfected with a dominant-negative interfering mutant c-jun, TAM-67, and expressing high levels of mutant jun exhibited approximately 50% blockage of VES-mediated apoptosis. In addition to increased c-jun expression after VES treatment, VES-treated MCF-7 cells exhibited elevated activator protein-1 (AP-1) binding activity. Comparisons of AP-1 binding factors by super-shift analyses with jun-specific antibodies in cells sensitive to VES-induced apoptosis (empty-vector control 7-1 cells) and cells resistant to VES-induced apoptosis (TAM-67-containing TAM-9 cells) showed that the sensitive cells expressed c-jun and jun D and the resistant cells TAM-67 AP-1 binding proteins after VES treatment. These studies suggested that c-jun may be involved in the apoptotic process initiated by VES treatment of human MCF-7 breast cancer cells.

Growth and reproductive development from weaning through 20 months of age among breeds of bulls in subtropical Florida.

To determine the effect of breed on growth and reproductive development, weaned bulls in each of 2 yr were managed as a single group for approximately a year. In Year 1, the study group consisted of 24 Angus, 24 Brahman, 20 Hereford and 14 Senepol bulls, while in Year 2, it contained 25 Angus, 17 Brahman. 13 Romosinuano and 9 Nellore x Brahman bulls. Body and testicular growth measurements were recorded at 6-wk intervals. At approximately 1 yr of age and quarterly thereafter (4 periods), bulls were evaluated for libido, pubertal status, and GnRH-induced LH and testosterone secretion. Significant breed-by-age interactions occurred for most growth measurements. Brahman bulls (Bos indicus ) were (P < 0.05) older and heavier at puberty than Angus, Hereford, Senepol and Romosinuano bulls (Bos taurus ). Libido scores were lowest for Brahman and Nell ore x Brahman bulls (Bos indicus ). highest for Angus and Hereford bulls (temperate Bos taurus breeds) and intermediate for Senepol and Romosinuano bulls (tropical Bos taurus breeds; P < 0.05). Differences were not consistent among breeds or between years for GnRH-induced LH secretion. In both years, basal testosterone concentrations and areas under the GnRH-induced testosterone curve were higher (P < 0.05) for Angus and Hereford bulls (temperate breeds) than for Brahman, Senepol, Romosinuano and Nellore x Brahman bulls (tropical breeds). In conclusion, reproductive development of Senepol and Romosinuano bulls (tropical Bos taurus breeds) was more similar to Angus and Hereford bulls (temperate Bos taurus breeds) than to Brahman and Nellore x Brahman bulls (Bos indicus ).

Evidence for role of transforming growth factor-beta in RRR-alpha-tocopheryl succinate-induced apoptosis of human MDA-MB-435 breast cancer cells.

MDA-MB-435 human breast cancer cells treated with 10 micrograms/ml of RRR-alpha-tocopheryl succinate (vitamin E succinate, VES) for one, two, three, and four days exhibit 9%, 19%, 51%, and 73% apoptotic cells, respectively. Likewise, cells cultured for one, two, and three days with conditioned media (CM) obtained from MDA-MB-435 cells treated with VES exhibit 10%, 36%, and 74% apoptosis, respectively. A quantitative luciferase-based assay showed CM from VES-treated cells collected at 24 and 48 hours after treatment initiation to contain 75 and 32 pg of active transforming growth factor-beta (TGF-beta), respectively, per 10(6) cells. Although purified TGF-beta 1 is not an effective apoptotic agent for MDA-MD-435 cells, cotreatment of the cells for three days with suboptimal levels of VES (2.5 and 5 micrograms/ml) + 10 ng/ml of purified TGF-beta 1 enhanced apoptosis by 66% and 68%, respectively. Interference of the TGF-beta-signaling pathway by transient transfection of MDA-MB-435 cells with antisense oligomers to TGF-beta type II receptor (TGF-beta R-II) blocked VES-induced apoptosis. Likewise, addition of neutralizing antibodies to TGF-beta 1 or to all three mammalian isoforms of TGF-beta (TGF-beta 1, -beta 2, -beta 3) blocked VES- and CM-induced apoptosis. Furthermore, inhibitors of TGF-beta conversion from an inactive latent form to a biologically active form inhibited VES-induced apoptosis. In summary, the ability to reduce apoptosis by blocking TGF-beta or the TGF-beta receptor-signaling pathway with antisense oligomers or ligand-neutralizing antibodies or prevention of activation of TGF-beta indicates a role for TGF-beta signaling in VES-induced apoptosis.

The effect of a diagnostic label of language delay on adults' perceptions of preschool children.

The effects of the label of expressive language disorder (ELD) on adults' perceptions of preschoolers were investigated. Twenty adults interacted with 3 children of typical development and one child previously diagnosed with ELD. Adults were randomly assigned to a label group (in which the child with ELD was identified) or a nonlabel group (in which the child with ELD was not identified). After interacting with dyads of children, adults ranked them according to behavioral characteristics and competencies. Results indicated that the nonlabel group ranked the child with ELD as significantly less likable and less productive, and they predicted less academic competence from her. In contrast, the label group did not differentiate the children behaviorally, but they predicted less social competence from the child with ELD. Implications regarding the use of labels in the inclusion of children with disabilities are discussed.

Evaluation of growth curves of Brahman cattle of various frame sizes.

Partial stage and complete life-cycle growth curves of Brahman cattle were obtained for small, medium, and large frame sizes for a herd under grazing conditions in a subtropical environment. Data were grouped into three stages: birth to weaning (stage 1), weaning to 20 mo (males) or 32 mo (females) of age (stage 2), and 32 mo of age to maturity (females only; stage 3). Within each stage, multiplicative growth models were developed for each frame size and sex. Body weight growth on age t was represented as exp(a + bt + ct2) for stages 1 and 2, and as exp(A + B exp(kt)) for stage 3. The effects of sire and progeny within sire were considered in all models. For stages 2 and 3, the effect of season was also included. To obtain complete life-cycle curves, a growth stage-multiplicative model with stages 1 and 2 was defined; stage 3 was also included for females. Due to a 1-mo adaptation period after weaning, a transition stage between stages 1 and 2 was defined and represented by the model exp(a + bt). In stage 1, the shape of the growth curve differed (P < .05) among frame size groups; sex did not affect the shape of the growth curves, but bull calves had heavier (P < .05) weights than heifer calves. In stage 2, the shape of the growth curves did not differ among frame sizes, but BW differed among frame sizes (P < .05) and sex affected (P < .05) the shape of the growth curves. In stage 3, the shape of the growth curves differed (P < .05) among frame sizes. There were sire effects (P < .05) for stages 1 and 2, but sire effects were not significant for stage 3. Season effects were important (P < .05) for stages 1 and 2. These results suggest that variability in growth patterns provides an opportunity to use management and nutrition to improve production efficiency in cattle of different frame sizes.

RRR-alpha-tocopheryl succinate enhances TGF-beta 1, -beta 2, and -beta 3 and TGF-beta R-II expression by human MDA-MB-435 breast cancer cells.

The proliferation of MDA-MB-435 human breast cancer cells was inhibited by RRR-alpha-tocopheryl succinate (vitamin E succinate, VES). Conditioned media (CM) from VES growth-inhibited cells contained potent antiproliferative activity, part of which is contributed by transforming growth factor-beta (TGF-beta) isoforms. Antibody neutralization analysis, employing TGF-beta isoform-specific antibody reagents, showed that TGF-beta 1, -beta 2, and -beta 3 were present in the CM from VES-treated cells. Culturing MDA-MB-435 cells with VES did not alter the levels of constitutively expressed 2.4-kb TGF-beta 1, 3.0- and 4.0-kb TGF-beta 2, or 1.2- and 3.5-kb TGF-beta 3 mRNA transcripts. Inhibition of DNA synthesis by MDA-MB-435 cells was increased by combinations of suboptimal levels of VES and purified TGF-beta 1. VES-treated MDA-MB-435 cells exhibited enhanced binding of radiolabeled TGF-beta 1, and Western immunoblotting analyses showed that VES treatment enhanced TGF-beta type II receptor protein expression. TGF-beta type I receptor protein levels were not modified by VES treatments. Although the mRNA transcript for the 5.5-kb TGF-beta type II receptor was upregulated after four hours of treatment with VES, this treatment did not modify the 6.5-kb TGF-beta type I or the 6.5-kb TGF-beta type II receptor mRNAs. Results demonstrate that biologically active TGF-beta 1, -beta 2, -beta 3 and levels of TGF-beta type II receptor expressed by human breast cancer cells are enhanced by VES treatment.

RRR-alpha-tocopheryl succinate inhibits DNA synthesis and enhances the production and secretion of biologically active transforming growth factor-beta by avian retrovirus-transformed lymphoid cells.

The RRR-alpha-tocopheryl succinate form of vitamin E, referred to as vitamin E succinate (VES), inhibits the proliferation of avian reticuloendotheliosis virus-transformed RECC-UTC4-1 (C4-1) lymphoblastoid cells in a dose-dependent manner in vitro. Analyses of conditioned medium (CM) from VES growth-inhibited cells revealed a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor-beta (TGF-beta) was established by 1) growth inhibition of TGF-beta-responsive Mv1Lu mink lung and murine CTLL-2 cell lines, 2) a combination of physical characteristics including heat stability, acid stability, and Bio-Gel P-60 column chromatography elution profile, 3) neutralization of the antiproliferative activity by antibodies specific for TGF-beta, and 4) immunoprecipitation of metabolically labeled TGF-beta in CM from VES-treated C4-1 cells by use of TGF-beta-specific antibodies. Northern blot analyses of total cellular RNA revealed that VES does not alter the levels of constitutively expressed TGF-beta isoform-specific mRNAs; namely, VES does not alter the levels of the 3.9- and 4.1-kb TGF-beta 2 mRNAs, the 3.0-kb TGF-beta 3 mRNA, or the 2.5-, 2.7-, and 1.7-kb TGF-beta 4 mRNAs. The data show that VES inhibits C4-1 cell proliferation and induces the cells to produce and secrete active forms of TGF-beta, suggesting that one mechanism whereby VES inhibits C4-1 cell proliferation may be via the TGF-beta pathway for cellular growth control.

RRR-alpha-tocopheryl succinate inhibits proliferation and enhances secretion of transforming growth factor-beta (TGF-beta) by human breast cancer cells.

The RRR-alpha-tocopheryl succinate form of vitamin E inhibits the proliferation of estrogen receptor-positive and estrogen receptor-negative human breast cancer cell lines in a dose-dependent manner in vitro. Analyses of cell-conditioned medium from RRR-alpha-tocopheryl succinate growth-inhibited cells revealed the presence of a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor-beta (TGF-beta) was established by 1) growth inhibition of the TGF-beta-responsive Mv1Lu-CCL-64 mink lung and murine CTLL-2 cell lines, 2) combination of physical characteristics including heat stability, acid stability, and Bio-Gel P-60 column chromatography elution profile, and 3) neutralization of the antiproliferative activity in the conditioned media by antibodies specific for TGF-beta.

Family history in developmental expressive language delay.

Familial aggregation of language deficits has been demonstrated in previous studies. However, researchers have typically failed to differentiate subgroups of language-impaired children. The present study used questionnaire data to assess the family history of speech, language, and school problems in a group of young children with developmental expressive language delay (ELD) and in a sample of normally developing children. In contrast to previous studies of language and speech problems, no strong familial component of ELD was found. Further, family history was not predictive of later language development in ELD children. These findings argue against genetic and familial causes of ELD and attest to the importance of differentiating subtypes of early language problems.

The effects of incidental teaching on vocabulary acquisition by young children.

The effects on vocabulary acquisition of child-initiated versus adult-initiated instances of adult labeling were studied. 16 monolingual, English-speaking preschool children were exposed to a Spanish-speaking adult. In order to have access to toys placed out of their reach, children had to request the toys in Spanish. For the experimental group, adult labeling occurred when the children expressed interest in the toy. Control group children were yoked temporally to experimental group children for the purpose of adult labeling. Thus, adult labeling for the control group was randomly related to the children's expressions of interest. Although both groups of children learned some Spanish words, children in the experimental group produced significantly more Spanish words during the training sessions and showed superior performance on posttraining tests of Spanish production. Levels of comprehension of the Spanish words were equivalent for both groups. Results are interpreted in the context of the literature on "incidental teaching" and are viewed as demonstrating the critical role in language acquisition of the timing of exposure to language models.

What is the role of reinforcement in early language acquisition?

Monolingual American and Mexican 2- and 3-year-old children were exposed to a foreign language in a naturalistic but controlled environment. Children were randomly assigned to 2 groups. 1 group was differentially reinforced throughout the study for the use of foreign vocabulary. The control group was first reinforced nondifferentially for use of the native language or the foreign language and later was switched to differential reinforcement for the foreign language. Frequencies of spontaneous foreign word production and other verbal responses were computed, and formal assessments of comprehension and production of the foreign words were conducted. Differential reinforcement resulted in accelerating frequencies of spontaneous foreign language use and better performance on both comprehension and production tests. Under nondifferential reinforcement, rates of spontaneous foreign language use were low and static. Results are interpreted as evidence that the acquisition of expressive vocabulary is a function of socially mediated reinforcement.

Organización hospitalaria en caso de desastre / Hospital organization under disaster conditions

Se describen en este trabajo el sistema nacional de salud de Cuba y, fundamentalmente, el estado de la organización de las unidades de Defensa Civil, así como su participación en las situaciones de desastre. Se expllican el plan de emergencias aplicado por nuestras unidades y, finalmente, las experiencias obtenidas por Cuba mediante la ayuda prestada a otros países en los cuales han ocurrido desastres (AU)