8 halogenated aliphatic hydrocarbons were assayed for their ability to induce somatic segregation in the mould Aspergillus nidulans. Induction of haploidization, mitotic non-disjunction and mitotic ...crossing-over was studied in heterozygous colonies exposed to the tested chemicals through the detection and phenotypic analysis of segregated sectors. The results obtained show that 1,2-dibromoethane induced all kinds of segregated sectors; 1,2-dichloroethane, allyl chloride, 2-chloroethanol, 2,2-dichloroethanol and 2,2-dichloroacetaldehyde significantly increased the frequency of haploid sectors and diploid non-disjunctional sectors; chloroform and 1,2-dichloropropane were ineffective.
To describe the sociodemographic characteristics and sexual and drug use behaviors of men with AIDS who engage in bisexual activity.
We interviewed 2120 men aged > or = 18 years who were reported ...with AIDS in 11 states and cities. Men were considered bisexual if they reported having had sex with a man and a woman in the previous 5 years.
Of the 2020 men with AIDS who reported being sexually active in the previous 5 years, 1150 (57%) had had male partners only, 522 (26%) had had female partners only and 348 (17%) had had both. White men were least likely to report bisexual behavior (15%; 161 out of 1071). Men of Latin American descent were most likely to report bisexual behavior (24%; 37 out of 155), especially those born outside the United States who had lived there for < or = 10 years (38%; 11 out of 29). Bisexual Latin American men, regardless of birthplace, were more likely to be currently married than all other bisexual men (22 versus 7%; P < 0.05). HIV risk behaviors differed between men reporting bisexual and those reporting exclusively homosexual or heterosexual activity. Injecting drug use in the previous 5 years was more common among bisexual than homosexual men (12 versus 6%; P < 0.05). Bisexual men were more likely (P < 0.05) to have received money for sex (11%) than homosexual (4%) or heterosexual men (4%). This difference was even greater among injecting drug users receiving money for sex: bisexual (29%), homosexual (13%), heterosexual (3%).
Demographics and HIV risk behaviors of bisexual men with AIDS differ from those of homosexual and heterosexual men with AIDS. These findings indicate that special efforts are needed to prevent sexual transmission of HIV among bisexual men.
The biological activity of 24 chlorinated aliphatic hydrocarbons has been studied in the mold Aspergillus nidulans. The ability to induce chromosome malsegregation, lethality and mitotic growth ...arrest has been experimentally determined for each chemical. These data, together with those of 11 related compounds previously investigated, generated a data base which was used for quantitative structure-activity relationship (QSAR) analysis. To this aim, both physico-chemical descriptors and electronic parameters of each compound have been calculated and included in the analysis. The QSAR analysis indicated that toxic effects induced by chlorinated aliphatics in A. nidulans are mainly dependent on steric factors, as indicated by the correlation with molar refractivity (MR). Conversely, the ease with which they accept electrons, parametrized by LUMO (energy of the lowest unoccupied molecular orbital), plays a prevailing role in determining the aneuploidizing properties. An involvement of free radicals, generated by the reductive metabolism of haloalkanes, is hypothesized as an explanation of the data.
The present study reports the effects of retinoic acid (RA) on cultured fetal rat hepatocytes. We show that RA treatment induces both differentiation and apoptosis. Hepatocytes cultured for 48 hours ...in the presence of 5 μmol/L RA form junctional complexes in the areas of contact between neighboring cells and develop bile canaliculi, typical features of mature and well‐differentiated cells. At the same time, about 20% of cells are induced to die by apoptosis, and the percentage of apoptotic cells increases according to the concentration of RA used and the duration of treatment. The induction of apoptosis, studied at the morphological and biochemical levels, revealed that, in our system, the classical compaction of chromatin occurs only during the final stages of the process; instead of the common marker of apoptosis, i.e., the “DNA ladder” pattern of fragmentation, megabase‐sized fragments were found. These observations provide further evidence of the existence of fundamental differences in the mechanisms of apoptosis among cell types. To investigate the molecular mechanism of the effects of RA, we evaluated the expression of two proteins, c‐myc and p53, which are known to be involved in both cell differentiation and apoptosis. The data obtained show that the amount of p53 remained unchanged after RA treatment. On the contrary, a dose‐dependent reduction in c‐myc levels was found, suggesting that RA action may be mediated by modulation of this oncogene. Our findings regarding the apoptosis‐inducing effect of RA, which was not found in adult hepatocytes, suggest a possible relationship between this phenomenon and the proliferative capacity and/or differentiation state of hepatocytes.
A family is described with 20 members in three successive generations affected by optic atrophy without other ocular or extraocular manifestations. The anomaly was transmitted as an ...autosomal-dominant character. There was a clearly bimodal distribution of severity: 4 male patients complained of severe impairment of vision since childhood while 16 other subjects (7 males and 9 females) were completely asymptomatic. This family could be an example of a new variety of autosomal dominant optic atrophy characterized by sex-influenced severity.
We evaluated the effect of IFN-beta on the expression of transferrin receptor (TfR) during the in vitro differentiation of peripheral blood monocytes to macrophages. IFN-beta exerted a strong ...inhibitory effect on the expression of TfR. As little as 0.1 IU/ml was sufficient to induce a 40% reduction of transferrin (Tf) binding sites on 7-day cultured macrophages. Scatchard plot analysis revealed that this impaired Tf binding in IFN-beta-treated macrophages was not due to a decreased affinity of the TfR for its ligand but to a reduction in the number of cell surface TfR. IFN-gamma did not exert any significant effect on the expression of TfR, even though it was capable of partially reverting the inhibitory effect of the IFN-beta on Tf binding. To understand the mechanism by which IFN-beta inhibited TfR expression, we examined the expression of TfR mRNA, 125I-Tf binding to detergent-solubilized cells, and TfR cellular distribution. The results of these experiments showed that IFN-beta caused neither a significant alteration of the expression of TfR mRNA nor a decrease of the total content of TfR molecules. Moreover, immunofluorescence analysis of TfR localization indicated that TfR was clustered in an intracellular compartment in IFN-beta-treated macrophages. These data demonstrate that IFN-beta is capable of dramatically down-modulating TfR in macrophages by post-translational mechanisms (i.e., by sequestering this receptor in intracellular compartments).
Inicialmente hacemos una descripción sobre la fisiología endocrina de la implantación y la importancia que juega el cuerpo lúteo en esta fase temprana de la gestación. Seguidamente entramos a ...considerar la endocrinología placentaria y su papel como órgano endocrino secretor de la gonadotropina coriónica, esteroides ováricos, corticosteroides, andrógenos, HPL y protaglandinas. Hacemos hincapié en el concepto de la unidad feto—placentaria como entidad sintetizadora del estriol, el más importante de los compuestos estrogénicos producidos en el embarazo y su valor como medio diagnóstico del ambiente fetal. Posteriormente se describen los cambios endocrinos que sufre la madre al incorporarse la placenta a su organismo, lo cual significa que tiene un nuevo órgano secretor interno. Estos cambios se realizan en su función ovárica, en su hipófisis, en su tiroides, paratiroides, páncreas y corteza suprarrenal. A medida que el feto alcanza su término, sus glándulas endocrinas empiezan a mostrar actividad. Se revisa entonces el sistema endocrino—fetal referente a todas las glándulas endocrinas clásicas (gonadas, hipófisis, tiroides, etc.) y en particular al timo. A continuación se entra a considerar el parto, sus diferentes períodos y sus mecanismos desencadenantes (inervación motora autónoma, estrógenos, ambiente externo, stress fetal, ACTH, corticosteroides, estimulación mecánica, ocitocina, progesterona y prostaglandinas). Después mencionamos brevemente los cambios que se observan el puerperio o sea el tiempo comprendido entre el parto y el retorno de los genitales externos e internos de la madre a su estado previo al embarazo. Este período dura de 6 a 8 semanas. Finalmente entramos a considerar los aspectos endocrinos de la lactancia: la lactogénesis y la influencia que sobre ella tienen las hormonas hipofisiarias, la prolactina, los glucocorticoides y las hormonas ováricas y placentarias; el amamantamiento y estímulo de succión, y por último, la galactopoyesis.
Three chloromethanes (dichloromethane, chloroform and carbon tetrachloride) and 8 chlorinated ethanes (1,1- and 1,2-dichloroethane, 1,1,1- and 1,1,2-trichloroethane, 1,1,1,2- and ...1,1,2,2-tetrachloroethane, pentachloroethane and hexachloroethane) were assayed in tests for the induction of mitotic segregation in Aspergillus nidulans diploid strain P1. Eight of the 11 compounds assayed (dichloromethane, chloroform, carbon tetrachloride, 1,1- and 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1,2- and 1,1,2,2-tetrachloroethane) significantly increased the frequency of morphologically abnormal colonies which produced euploid whole-chromosome segregants (haploids and non-disjunctional diploids). Only in one case (1,1,1,2-tetrachloroethane) was a borderline increase in crossing-over frequency observed, thus suggesting the involvement of non-DNA targets in aneuploidy induction by these chlorinated hydrocarbons. Conclusive evidence for the induction of aneuploidy as the primary genetic event was provided by experiments in haploid strain 35 with 1,2-dichloroethane and 1,1,1,2-tetrachloroethane. Mutagenic, lethal and growth-arresting activities were quantitatively estimated and compared to a series of descriptors of physical and chemical properties of the molecules by means of multivariate statistical analysis. Lipophilicity, known to be related to c-mitotic activity, did not show any significant relationship with aneuploidizing activity, whereas a possible correlation among physico-chemical descriptors and toxic properties of test chemicals was highlighted.
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