An objective auditory measure to assess speech recognition in adult cochlear implant users.

OBJECTIVE: To verify if a mismatch negativity (MMN) paradigm based on speech syllables can differentiate between good and poorer cochlear implant (CI) users on a speech recognition task. METHODS: Twenty adults with a CI and 11 normal hearing adults participated in the study. Based on a speech recognition test, ten CI users were classified as good performers and ten as poor performers. We measured the MMN with /da/ as the standard stimulus and /ba/ and /ga/ as the deviants. Separate analyses were conducted on the amplitude and latency of the MMN. RESULTS: A MMN was evoked by both deviant stimuli in all normal hearing participants and in well performing CI users, with similar amplitudes for both groups. However, the amplitude of the MMN was significantly reduced for the poorer CI users compared to the normal hearing group and the good CI users. The latency was longer for both groups of cochlear implant users. A bivariate correlation showed a significant positive correlation between the speech recognition score and the amplitude of the MMN. CONCLUSIONS: The MMN can distinguish between CI users who have good versus poor speech recognition as assessed with conventional tasks. SIGNIFICANCE: Our findings suggest that the MMN can be use to assess speech recognition proficiency in CI users who cannot be tested with regular speech recognition tasks, like infants and other non-verbal populations.

Regulation of sex steroid formation by interleukin-4 and interleukin-6 in breast cancer cells.

Sex steroids play a predominant role in the development and differentiation of normal mammary gland as well as in the regulation of hormone-sensitive breast cancer growth. There is evidence suggesting that local intracrine formation of sex steroids from inactive precursors secreted by the adrenals namely, dehydroepiandrosterone (DHEA) and 4-androstenedione (4-dione) play an important role in the regulation of growth and function of peripheral target tissues, including the breast. Moreover, human breast carcinomas are often infiltrated by stromal/immune cells secreting a wide spectra of cytokines. These might in turn regulate the activity of both immune and neoplastic cells. The present study was designed to examine the action of cytokines on 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) activities in human breast cancer cells. The various types of human 17beta-HSD (five types) and 3beta-HSD (two types), because of their tissue- and cell-specific expression and substrate specificity, provide each cell with necessary mechanisms to control the level of intracellular active androgens and estrogens. We first investigated the effect of exposure to IL-4 and IL-6 on reductive and oxidative 17beta-HSD activities in both intact ZR-75-1 and T-47D human breast cancer cells. In ZR-75-1 cells, a 6 d exposure to IL-4 and IL-6 decreased E2-induced cell proliferation, the half maximal inhibitory effect being exerted at 88 and 26 pM, respectively. In parallel, incubation with IL-4 and IL-6 increased oxidative 17beta-HSD activity by 4.4- and 1.9-fold, respectively, this potent activity being observed at EC50 values of 22.8 and 11.3 pM, respectively. Simultaneously, reductive 17beta-HSD activity leading to E2 formation was decreased by 70 and 40% by IL-4 and IL-6, respectively. Moreover, IL-4 and IL-6 exerted the same regulatory effects on 17beta-HSD activities when testosterone and 4-dione were used as substrates, thus strongly suggesting the expression of the type 2 17beta-HSD ZR-75-1 cells. In contrast, in T-47D cells, IL-4 increased the formation of E2, whereas IL-6 exerts no effect on this parameter. However, we found that T-47D cells failed to convert testosterone efficiently into 4-DIONE, thus suggesting that there is little or no expression of type 2 17beta-HSD in this cell line. The present findings demonstrate that the potent regulatory effects of IL-4 and IL-6 on 17beta-HSD activities depend on the cell-specific gene expression of various types of 17beta-HSD enzymes. We have also studied the effect of cytokines on the regulation of the 3beta-HSD expression in both ZR-75-1 and T-47D human breast cancer cells. Under basal culture conditions, there is no 3beta-HSD activity detectable in these cells. However, exposure to IL-4 caused a rapid and potent induction of 3beta-HSD activity, whereas IL-6 failed to induce 3beta-HSD expression. Our data thus demonstrate that cytokines may play a crucial role in sex steroid biosynthesis from inactive adrenal precursors in human breast cancer cells.

Localization and regulation of expression of the FAR-17A gene in the hamster flank organs.

A quantitative in situ hybridization study was carried out to determine the precise localization and androgen regulation of the flank organ regulated (FAR-17A) mRNA expression in the different cellular components of the hamster flank organs. Although FAR-17A mRNA was highly expressed in the epithelial cells of the sebaceous glands, it was also found in the outer root sheath of the hair follicles and in melanocytes. The changes in FAR-17A mRNA levels, in the size of the flank organ and sebaceous gland areas as well as in the weight of the seminal vesicles and prostate, were compared following castration and after 5alpha-dihydrotestosterone treatment. FAR-17A mRNA levels were already significantly decreased 1 d after castration, in parallel with a concomitant decrease in the number of labeled cells with the FAR-17A probe. A maximal decrease was found 7 d after castration. The other parameters were significantly reduced later. After 7 d of treatment with dihydrotestosterone, all values returned to those found in intact animals. Similar stimulatory effects on these parameters were observed after treatment with the adrenal sex steroid precursor dehydroepiandrosterone. These data show that all of the components of the flank organs (sebaceous glands, hair follicles, and melanocytes) express the flank organ regulated (17A) type gene (FAR-17A) gene and that its expression is stimulated by treatment with either dihydrotestosterone or dehydroepiandrosterone. Moreover, FAR-17A mRNA levels respond to androgen stimulation more rapidly than the standard morphologic parameters, revealing that the FAR-17A gene could be a more sensitive and cell specific marker to study the mechanisms of androgen action in the skin.

The accessibility of yeast ribosomal protein L1 as probed by proteolysis and site-directed mutagenesis is different in intact 60 and 80 S ribosome.

Accessible regions of protein L1 in intact 60 and 80 S ribosomes from Saccharomyces cerevisiae were first detected by controlled proteolysis. The N-terminal region of L1 in either 60 S or 80 S particles, was inaccessible to proteases, but the central and C-terminal regions were accessible. The accessibility of the central region differed depending on the ribosome state. These regions were further examined by determination of the chemical reactivity of specific cysteine residues introduced into these regions by site-directed mutagenesis. All cysteine mutant proteins were capable of binding yeast 5 S rRNA in vitro and the ribosomes containing the mutant proteins were functional in vivo. Residues Cys-257 and Cys-275 were modified in both the 60 and 80 S ribosomes but the modification rates were different in the two ribosome states. Both residues Cys-62 and Cys-286 were inaccessible in 80 S or 60 S ribosomes. Taken together, the present study identified several accessible regions of L1 in intact ribosomes and further showed that the accessibility of some of the regions was altered upon ribosomal subunit association. The most likely interpretation of these results is that the conformation of the ribosomal protein L1 was altered upon ribosomal subunit association.

Structure-function relationships and molecular genetics of the 3 beta-hydroxysteroid dehydrogenase gene family.

The isoenzymes of the 3 beta-hydroxysteroid dehydrogenase/5-ene-4-ene-isomerase (3 beta-HSD) gene family catalyse the transformation of all 5-ene-3 beta-hydroxysteroids into the corresponding 4-ene-3-keto-steroids and are responsible for the interconversion of 3 beta-hydroxy- and 3-keto-5 alpha-androstane steroids. The two human 3 beta-HSD genes and the three related pseudogenes are located on the chromosome 1p13.1 region, close to the centromeric marker D1Z5. The 3 beta-HSD isoenzymes prefer NAD+ to NADP+ as cofactor with the exception of the rat liver type III and mouse kidney type IV, which both prefer NADPH as cofactor for their specific 3-ketosteroid reductase activity due to the presence of Tyr36 in the rat type III and of Phe36 in mouse type IV enzymes instead of Asp36 found in other 3 beta-HSD isoenzymes. The rat types I and IV, bovine and guinea pig 3 beta-HSD proteins possess an intrinsic 17 beta-HSD activity specific to 5 alpha-androstane 17 beta-ol steroids, thus suggesting that such "secondary" activity is specifically responsible for controlling the bioavailability of the active androgen DHT. To elucidate the molecular basis of classical form of 3 beta-HSD deficiency, the structures of the types I and II 3 beta-HSD genes in 12 male pseudohermaphrodite 3 beta-HSD deficient patients as well as in four female patients were analyzed. The 14 different point mutations characterized were all detected in the type II 3 beta-HSD gene, which is the gene predominantly expressed in the adrenals and gonads, while no mutation was detected in the type I 3 beta-HSD gene predominantly expressed in the placenta and peripheral tissues. The mutant type II 3 beta-HSD enzymes carrying mutations detected in patients affected by the salt-losing form exhibit no detectable activity in intact transfected cells, at the exception of L108W and P186L proteins, which have some residual activity (approximately 1%). Mutations found in nonsalt-loser patients have some residual activity ranging from approximately 1 to approximately 10% compared to the wild-type enzyme. Characterization of mutant proteins provides unique information on the structure-function relationships of the 3 beta-HSD superfamily.

The human type II 17 beta-hydroxysteroid dehydrogenase gene encodes two alternatively spliced mRNA species.

The isozymes of the 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) gene family are responsible for the formation of the 17 beta-hydroxysteroids delta 5-androstene-3 beta,17 beta-diol, testosterone, 17 beta-estradiol, and dihydrotestosterone from their corresponding 17-ketosteroid precursors, thus playing a pivotal role in the formation of active sex steroids in both steroidogenic and peripheral target tissues. To clone the type II 17 beta-HSD gene, the full-length cDNA type II 17 beta-HSD was used as probe to screen a human leukocyte genomic DNA library. The type II 17 beta-HSD gene contains seven exons and spans > 40 kbp. The type II 17 beta-HSD gene encodes two alternatively spliced mRNAs that give rise to the previously identified type IIA 17 beta-HSD protein of 387 amino acids, as well as to a related 291-amino-acid type IIB 17 beta-HSD protein of unknown function. RNA blot analysis revealed the presence of a major 1.45-kb transcript that is abundant in placenta and endometrium. The mRNA cap site has been localized in a region between 179 and 167 nucleotides upstream of the ATG start codon by RNase protection and S1 nuclease mapping analyses. Cloning of the 17 beta-HSD type II gene provides us with the tools to study its transcriptional expression.

Structure and tissue-specific expression of a novel member of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family. The exclusive 3 beta-HSD gene expression in the skin.

Structures of cDNA clones encoding three members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family were characterized. To search for potential new types of 3 beta-HSD, rat types I and II 3 beta-HSD cDNAs were used as probes to screen a rat genomic DNA library. Among the clones isolated, one encodes a novel predicted rat 3 beta-HSD isoenzyme, chronologically designated type IV. The corresponding full-length cDNA was thereafter isolated by selective polymerase chain reaction amplification from rat ovary and day-15 placenta cDNA libraries. The rat type IV 3 beta-HSD cDNA encodes a predicted 372-amino acid protein of 41,854 daltons, which shares 90.9, 87.9, and 78.8% sequence identity with rat types I, II, and III proteins, respectively. Ribonuclease protection assay reveals that type IV 3 beta-HSD is the sole 3 beta-HSD mRNA species detectable in the skin and represents the predominant species in the placenta while being also detectable in the ovary and, to a lower degree, in the adrenal gland. Transient expression of type IV cDNA in SW-13 cells indicates 3 beta-HSD activity similar to that of rat type I 3 beta-HSD. The presence of multiple 3 beta-HSD genes should permit differential and tissue-specific regulation of this rate-limiting enzymatic activity essential in the biosynthesis of all classes of steroid hormones in both classical steroidogenic and intracrine peripheral tissues.

Lack of antiglomerular basement membrane antibody binding to alveolar membranes after hydrocarbon exposure in rats.

A causal relationship has been proposed for the development of Goodpasture's syndrome and hydrocarbon (gasoline) exposure in man. Infusion of antiglomerular basement membrane antibody into rats subjected to gasoline inhalation did not result in linear binding to alveolar basement membranes suggesting that the endothelial barriers remained intact despite administration of near lethal doses of gasoline.

Unilateral glomerular DNA-anti-DNA complex formation in situ.

DNA has a high affinity for collagenous structures such as glomerular basement membrane. DNA was infused into the isolated left kidney in rats to determine whether this antigen though negatively charged would bind to glomerular structures. Mainly mesangial localization with minimal capillary localization was noted. Infusion of anti-DNA antibody after glomerular DNA binding allowed for formation of DNA-anti-DNA deposits in situ.

Arachidonic acid infusion in rabbits. Renal pathologic alterations.

Arachidonic acid infusion in rabbits is highly lethal, death occurring in greater than 90% of animals and most within 1 to 2 minutes. This effect may be inhibited by prior administration of vitamin E. Pathologic examination of renal tissue from animals killed in this manner demonstrated immunoglobulin and fibrin deposition in the glomeruli and interstitium of the kidney. No pathologic alterations were detected by light microscopy. Electromicroscopy revealed some endothelial cell swelling with no evidence of electron dense deposits, indicating the absence of immune complexes. Pathologic examination of the kidneys suggest the deposition of immunoglobulin in a non complexed form.

Severe familial cholestasis in North American Indian children: a clinical model of microfilament dysfunction?

Studies of 14 North American Indian children with a familial type of severe neonatal cholestasis are described. Jaundice occurred during the neonatal period in 9 children, but disappeared before the end of the 1st yr. Progressive liver damage was documented by the persistence of high levels of alkaline phosphatase, moderate elevation of transaminases, and severe pruritus. Serum bile acids were constantly elevated (3.0-119.5 microgram/ml). Early portal hypertension and variceal bleeding necessitated portal-systemic shunts in 7 children. By light microscopy, the early stage was characterized by hepatitis with giant-cell transformation and biliary stasis. Later on, portal fibrosis became evident and was followed by cirrhosis. By electron microscopy bile canaliculi appeared slightly dilated with preservation or only partial loss of microvilli. They were surrounded by a prominent pericanalicular filamentous web. Immunofluorescence studies indicated the presence of action-containing microfilaments. This group of children might represent a human model of microfilament dysfunction-induced cholestasis.