[Risk of transmission of viral disease by needle punctures and cuts in hospital health care workers].

The accidental exposure of the health care workers (HCW) to blood and blood products constitutes a danger for transmission of blood-borne pathogens and the development of severe diseases. Most attention is focused on exposure to the viruses of hepatitis B, C and human immunodeficiency. The objectives of this prospective study were to determine the rate of exposure of our HCW to blood and blood products; to define the high risk groups; and to establish recommendations to prevent transmission or reduce the risk of exposure to these viruses. During the year 1996, 103 injuries from needle-puncture or other sharp objects were reported to our infectious diseases control unit. Most of those injured were women. 58.4% of the events occurred in the vicinity of the patient. The source of exposure was known in 60% of the cases. 73.8% of those injured had already been immunized against hepatitis B. The departments in which most exposures occurred were the operating theater (12.5%), medical departments A (10.6%) and B (9.6%), and the emergency department (7.7%). Nurses were at highest risk, constituting 47% of those injured. Our recommendations are that a continuous teaching program be established for the high risk groups; that HCW be urged to report every event of exposure; and to encourage HCW to undergo active immunization against hepatitis B.

Androgen regulation of a laryngeal-specific myosin heavy chain mRNA isoform whose expression is sexually differentiated.

The larynx, the vocal organ of Xenopus laevis, is sexually differentiated; male laryngeal muscle fibers are entirely fast twitch while female fibers are predominantly slow twitch. In adults, all male laryngeal muscle fibers express the mRNA for a laryngeal-specific myosin heavy chain (MHC), LM; female laryngeal muscle expresses LM in a subset of fast-twitch fibers. In juvenile females, LM expression is increased by exposure to exogenous androgen, suggesting that sexually differentiated expression of this laryngeal-specific MHC is regulated by exposure to male sex hormones. Here we examine hormonal regulation of LM expression in juvenile male and female frogs. Exposure to exogenous androgen increases LM expression in both sexes. In situ hybridization analyses of larynges reveal upregulation of LM expression within 8 hr of androgen treatment in males; upregulation is not evident until after 48 hr in females. The upregulation in juvenile females includes both an increase in the number of muscle fibers expressing LM and an increase in expression in fibers already expressing LM. In juvenile males, all fibers express LM from the end of metamorphosis on; levels of LM expression are increased in all fibers by androgen treatment. Androgen-induced increases in LM expression are prevented by treatment with cycloheximide and are thus dependent upon protein synthesis. Castration of juvenile males results in diminished LM expression relative to intact animals. We conclude that expression of LM is regulated by exposure to androgen and that this regulation accounts for the sexually differentiated phenotype.

Androgen-directed development of the Xenopus laevis larynx: control of androgen receptor expression and tissue differentiation.

The larynx of adult male Xenopus laevis differs markedly from that of the female; masculinization of the larynx requires androgen secretion during postmetamorphic development. Early in postmetamorphic development, androgen stimulates laryngeal cell proliferation and androgen binding activity is high. Later, androgen induces laryngeal cell differentiation and binding levels decrease. Here we explore the relation between laryngeal differentiation and androgen receptor expression. In untreated females, the larynx expresses high levels of androgen receptor mRNA early in postmetamorphic life; levels decline as females mature. The highest level of androgen receptor message is found in the undifferentiated laryngeal elastic precartilage of both sexes. When juveniles are exposed to androgen, laryngeal cell proliferation is stimulated within 48 hr in both sexes. Short exposures to androgen result in a biphasic response of AR mRNA levels; a marked down-regulation (4 hr) is followed by recovery at 8 hr (males) or 48 hr (females). Following longer periods of androgen treatment (3 weeks), AR mRNA expression is down-regulated and male-typical differentiation of elastic cartilage is induced in both sexes. Thus laryngeal growth responses to androgen are closely related to expression levels of androgen receptor mRNA.

Production of insulin-like growth factor binding proteins (IGFBPs) by human endometrial stromal cell is stimulated by the presence of embryos.

PURPOSE: To identify IGFBPs among endometrial secretory products and study their role in implantation and early embryo development. METHODS: Two-cell CB6F1 mouse embryos were cultured alone or with human endometrial stromal cells in RPMI 1640 plus 10% fetal calf serum (FCS) with or without addition of IGF-I (20 micrograms/ml), IGF receptor antibody (0.1 microgram/ml), progesterone (P) (20 ng/ml) and relaxin (R) (20 micrograms/ml). On the designated day, the medium was changed to protein-free RPMI and incubated for 16 h. Both conditioned medium and conditioned protein-free medium were then collected for protein analysis and immunoradiometric assay. Cells were fixed with 4% paraformaldehyde for immunohistochemical staining. RESULTS: IGFBP1 (31 kDa), IGFBP2 (36 kDa), IGFBP3 (45 kDa and 50 kDa) and an unknown IGFBP (25 kDa) were identified in conditioned medium of human endometrial stromal cells cultured alone or cocultured with mouse embryos. Secretion of IGFBPs by endometrial stromal cells was stimulated in the presence of mouse embryos as well as by P and R. IGFBP3 appears to be more responsive to embryonic signals. On the other hand, the secretion of IGFBP1 was greatly stimulated by P and R. Immunolocalization revealed that all three BPs were present in both embryonic and endometrial cells and their immunological staining was heavily increased by P and R. CONCLUSIONS: Endometrial stromal cells were able to synthesize and secrete IGFBPs to modify IGF action on embryo development. Secretion of IGFBPs was stimulated by embryonic signals and was hormonally dependent. The fact that IGFBP3 was more responsive to embryonic signals suggests that it may be important in early implantation. On the other hand, IGFBP1 production was highly responsive to both P and R, suggesting that it may be important throughout pregnancy. In addition, the fact that IGFBPs were located in endometrial and embryonic cells may suggest that these secretory products have autocrine and/or paracrine effects on both types of cells.

An androgen receptor mRNA isoform associated with hormone-induced cell proliferation.

The larynx of male Xenopus laevis undergoes an androgen-driven developmental transformation that enables the adult to produce his complex mate attraction song. During the early postmetamorphic period, androgen directs proliferation and differentiation of laryngeal muscle and cartilage. To explore the cellular and molecular basis of androgen control, we have cloned an androgen receptor cDNA from juvenile larynx. Here we identify two androgen receptor mRNA isoforms, alpha and beta, differing within the A/B, or hypervariable, domain. Northern blot analyses reveal that the beta isoform is transiently expressed during early juvenile stages, whereas the alpha transcript is expressed throughout postmetamorphic life. Using in situ hybridization and [3H]thymidine autoradiography, we examined the expression of androgen receptor mRNA isoforms during androgen-evoked cell proliferation and differentiation. The alpha and beta transcripts are coexpressed in proliferating tissues of the juvenile larynx; in postmitotic differentiated tissues, only the alpha transcript is expressed. Because androgen receptor beta mRNA is specifically expressed during hormone-evoked cell proliferation, we propose that this developmentally regulated mRNA isoform is required for the masculine program of cell addition within the developing vocal organ.

Sexually dimorphic expression of a laryngeal-specific, androgen-regulated myosin heavy chain gene during Xenopus laevis development.

Masculinization of the larynx in Xenopus laevis frogs is essential for the performance of male courtship song. During postmetamorphic (PM) development, the initially female-like phenotype of laryngeal muscle (slow and fast twitch fibers) is converted to the masculine form (entirely fast twitch) under the influence of androgenic steroids. To explore the molecular basis of androgen-directed masculinization, we have isolated cDNA clones encoding portions of a new Xenopus myosin heavy chain (MHC) gene. We have detected expression of this gene only in laryngeal muscle and specifically in males. All adult male laryngeal muscle fibers express the laryngeal myosin (LM). Adult female laryngeal muscle expresses LM only in some fibers. Expression of LM during PM development was examined using Northern blots and in situ hybridization. Males express higher levels of LM than females throughout PM development and attain adult levels by PM3. In females, LM expression peaks transiently at PM2. Treatment of juvenile female frogs with the androgen dihydrotestosterone masculinizes LM expression. Thus, LM appears to be a male-specific, testosterone-regulated MHC isoform in Xenopus laevis. The LM gene will permit analysis of androgen-directed sexual differentiation in this highly sexually dimorphic tissue.