Effect of dimethyl sulfoxide on human carcinoma cells, inhibition of plasminogen activator synthesis, change in cell morphology, and alteration of response to cholera toxin.

Human carcinoma HEp-3 lost its tumorigenic and metastatic potential upon prolonged culture in vitro. This change was accompanied by a reduced production of plasminogen activator (PA) of the urokinase type (uPA), which is secreted by HEp-3 cells, a change in response to effectors that modulate uPA production, and an alteration of cell morphology. Similar but more rapid changes occurred when malignant HEp-3 cells were exposed to dimethyl sulfoxide (DMSO). uPA activity in the culture medium dropped below 50% of the control level within 6 h after the addition of DMSO and became undetectable after 24 h of treatment. This drop in uPA activity was not caused by an increased production of PA inhibitors. The cell-associated uPA decreased to 25 to 30% of the control level within 6 h of DMSO treatment and remained at this level for at least 96 h; the reduced uPA production was partially accounted for by a rapid decrease in the functional and chemical concentration of uPA mRNA. In contrast, the concentrations of most of the abundant mRNA species did not appear to be significantly affected, and cell growth was only slightly inhibited in the presence of DMSO. Malignant HEp-3 cells treated with DMSO responded to cholera toxin with an enhanced production of uPA, and their morphology became indistinguishable from that of nonmalignant HEp-3 cells grown in vitro for prolonged periods of time. All of the above changes were fully and rapidly reversible. The inhibitory effect of DMSO on PA production appears to be specific for uPA of human cell lines.     

Imagerie des azoospermies d’origine excrétoire

Obstruction of the seminal tract is observed in 10 to 15% of men presenting with azoospermia or severe oligozoospermia (sperm count <1 million/ml) and with a normal FSH level. When ejaculate volume is normal, scrotal ultrasonography can detect, when clinical examination is unconclusive, enlarged hypoechoic epididymis or dilatation of the epididymal head. When biochemical markers are normal (carnitine and a1-4 glucosidase) a very proximal obstacle, located in the efferent cones can be responsible for the azoospermia; in this case, only sonography can detect dilatation of the rete-testis. Azoospermia with low, volume ejaculate and marked decrease of the fructose level in the semen, are related to a distal stenosis. Transrectal ultrasonography (TRUS) and endorectal MRI, performed in selected cases, show abnormalities which have to be interpreted according to the clinical setting. In case of bilateral absence of the vas deferens, scrotal ultrasonography is helpful if clinical examination is unconclusive; it shows a dilatation of the rete-testis and of the efferent ductules. The epididymal head can have a cystic-like appearance (spermatocele). TRUS shows the agenesia of the ampullae and agenesia or abnormalties of the seminal vesicles in 95% cases. In case of unilateral absence of the scrotal vas deferens, TRUS shows an ipsi-lateral agenesia of the ampulla and contralateral abnormalities suggesting a distal stenosis of the ejaculatory ducts. In case of bilateral palpable scrotal vas deferens, TRUS shows abnormalitites suggesting a distal obstruction of the ejaculatory ducts. The most frequent causes are congenital median cysts (Mullerian or Wolffian origin) and inflamatory stenosis of the ejaculatory ducts, which can occasionally be related to a ductal stone. TRUS is now routine part of the investigation of azoospermic patients with low volume ejaculate. Endorectal MRI better assesses than TRUS the relationships of the abnormality with the veru-montanum, which is useful when surgery is planned. Likewise, scrotal ultrasonography is useful when clinical examination is unconclusive and/or when biochemical sperm markers levels do not confirm an otherwise clinically suspected obstruction.     

Impact of surfactants on the biotransformation of methyl ricinoleate into γ-decalactone by Yarrowia lipolytica

Surfactants play a key role in the biotechnological degradation of hydrophobic substrates, however this role is often misunderstood. During the biotransformation of methyl ricinoleate into the aroma compound γ-decalactone by the yeast Yarrowia lipolytica, a direct contact occurs between the surface of the cells and the small droplets of substrate. The impact of a series of surfactants on this process was investigated. Both ionic surfactants tested were toxic towards the yeast. This effect may be linked to a decrease in the cell membrane integrity. The interfacial area of the emulsion varied according to the non-ionic surfactant used, and this factor was correlated with the productivity of the biotransformation. By evaluating the effect of surfactants on the capacity of the cells to adhere to decane (MATH test), it was shown that the adhesion of methyl ricinoleate on yeast surface is not a rate-limiting point for the process.