Adaptive Wiener Filtering for Improved Acquisition of Distortion Product Otoacoustic Emissions

An innovative acoustic noise canceling method using adaptive Wiener filtering (AWF) was developed for improved acquisition of distortion product otoacoustic emissions (DPOAEs). The system used one microphone placed in the test ear for the primary signal. Noise reference signals were obtained from three different sources: (a) pre-stimulus response from the test ear microphone, (b) post-stimulus response from a microphone placed near the head of the subject and (c) post-stimulus response obtained from a microphone placed in the subjects nontest ear. In order to improve spectral estimation, block averaging of a different number of single sweep responses was used. DPOAE data were obtained from 11 ears of healthy newborns in a well-baby nursery of a hospital under typical noise conditions. Simultaneously obtained recordings from all three microphones were digitized, stored and processed off-line to evaluate the effects of AWF with respect to DPOAE detection and signal-to-noise ratio (SNR) improvement. Results show that compared to standard DPOAE processing, AWF improved signal detection and improved SNR. © 1998 Biomedical Engineering Society. PAC98: 4364Jb, 4360-c, 8790+y     

Normal colon of Sprague-Dawley rats

Summary The patterns of expression of the human-tumor-associated antigens, CO17-1A, GA73-3, BR55-2, GICA19-9, CA50 and carcino-embryonic antigen (CEA) were studied in the normal colonic mucosa (the last three also in the serum) of Sprague-Dawley rats. Four immunohistochemically different segments were identified: caecum, ascending colon, transverse colon and descending colon. The immunohistochemical reactions of the cells at the lower part of the crypt were essential for the distinction of the four segments. In the caecum, the MAbs 17-1A, 73-3 and 19-9 stained the glycocalyx of the cells of the lower part of the crypts and the Golgi apparatus of the intercalated cells (IC). MAb55-2 stained very weakly the goblet-like cells (GLC) of the lower part of the crypt of transverse colon, in addition to a nearly complete lack of reaction in the upper part of the crypts. In the ascending colon, the lower part of the crypts showed a characteristic diffuse staining of the intercalated cells with MAb55-2. The perinuclear and mucosal staining observed in the GLC of the transverse colon with MAbs 17-1A, 73-3 and 19-9 as against the supranuclear and Golgi zone staining observed in the GLC/goblet cells (GC)/columnar cells (CC) of the lower part of crypts of the descending colon with the same MAbs, distinguished the former segment from the latter. The IC demonstrated by immunohistochemistry in the lower parts of the crypts of caecum and ascending colon appear to correspond to the replicating cells of the colonic crypts.     

Cohesin component dynamics during meiotic prophase I in mammalian oocytes

Cohesins are chromosomal proteins that form complexes involved in the maintenance of sister chromatid cohesion during division of somatic and germ cells. Three meiosis-specific cohesin subunits have been reported in mammals, REC8, STAG3 and SMC1 beta; their expression in mouse spermatocytes has also been described. Here we studied the localization of different meiotic and mitotic cohesin components during prophase I in human and murine female germ cells. In normal and atretic human fetal oocytes, from leptotene to diplotene stages, REC8 and STAG3 colocalize in fibers. In murine oocytes, SMC1beta, SMC3 and STAG3 are localized along fibers that correspond first to the chromosome axis and then to the synaptonemal complex in pachytene. Mitotic cohesin subunit RAD21 is also found in fibers that decorate the SC during prophase I in mouse oocytes, suggesting a role for this cohesin in mammalian sister chromatid cohesion in female meiosis. We observed that, unlike human oocytes, murine synaptonemal complex protein SYCP3 localizes to nucleoli throughout prophase I stages, and centromeres cluster in discrete locations from leptotene to dictyate. At difference from meiosis in male mice, the cohesin axis is progressively lost during the first week after birth in females with a parallel destruction of the axial elements at dictyate arrest, demonstrating sexual dimorphism in sister chromatid cohesion in meiosis.     

Dopamine enhancement of NMDA currents in dissociated medium-sized striatal neurons: role of D1 receptors and DARPP-32

Dopamine (DA), via activation of D1 receptors, enhances N-methyl-D-aspartate (NMDA)-evoked responses in striatal neurons. The present investigation examined further the properties of this enhancement and the potential mechanisms by which this enhancement might be effected. Dissociated medium-sized striatal neurons were obtained from intact rats and mice or mutant mice lacking the DA and cyclic adenosine 3',5' monophosphate (cAMP)-regulated phosphoprotein of M(R) 32,000 (DARPP-32). NMDA (10-1,000 microM) induced inward currents in all neurons. In acutely dissociated neurons from intact rats or mice, activation of D1 receptors with the selective agonist, SKF 81297, produced a dose-dependent enhancement of NMDA currents. This enhancement was reduced by the selective D1 receptor antagonist SKF 83566. Quinpirole, a D2 receptor agonist alone, produced small reductions of NMDA currents. However, it consistently and significantly reduced the enhancement of NMDA currents by D1 agonists. In dissociated striatal neurons, in conditions that minimized the contributions of voltage-gated Ca(2+) conductances, the D1-induced potentiation was not altered by blockade of L-type voltage-gated Ca(2+) conductances in contrast to results in slices. The DARPP-32 signaling pathway has an important role in D1 modulation of NMDA currents. In mice lacking DARPP-32, the enhancement was significantly reduced. Furthermore, okadaic acid, a protein phosphatase 1 (PP-1) inhibitor, increased D1-induced potentiation, suggesting that constitutively active PP-1 attenuates D1-induced potentiation. Finally, activation of D1 receptors produced differential effects on NMDA and gamma aminobutyric acid (GABA)-induced currents in the same cells, enhancing NMDA currents and inhibiting GABA currents. Thus simultaneous activation of D1, NMDA, and GABA receptors could predispose medium-sized spiny neurons toward excitation. Taken together, the present findings indicate that the unique potentiation of NMDA receptor function by activation of the D1 receptor signaling cascade can be controlled by multiple mechanisms and has major influences on neuronal function.     

Human TLR-7-, -8-, and -9-mediated induction of IFN-alpha/beta and -lambda Is IRAK-4 dependent and redundant for protective immunity to viruses

Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.     

Quantitation of hepatitis B viral DNA by solution hybridization: Comparison with DNA polymerase and hepatitis B e antigen during antiviral therapy

Serological markers of hepatitis B virus (HBV) replication were assessed in a randomized, controlled trial of prednisone withdrawal followed by α -interferon in the treatment of chronic hepatitis B. HBV DNA levels in more than 700 serial serum samples from 41 patients were determined by a sensitive and quantitative solution hybridization assay. Results were compared with HBV DNA polymerase (DNAp) activity and hepatitis B e antigen (HBeAg) in 21 untreated controls and 20 treated patients. Among treated patients, the mean pretherapy HBV DNA values were higher in nonresponders than in responders. During prednisone treatment, DNA levels increased an average of 2.1-fold in responders and 1.4-fold in nonresponders. During the 2-week rest interval between prednisone and interferon, DNA values fell an average of 57% in responders. In contrast, the mean DNA values in nonresponders did not change during the same interval. This early distinction between responders and nonresponders was not apparent from DNAp or HBeAg results. During interferon treatment, HBV DNA became undetectable in responders and remained negative during a 1-year follow-up. DNA in nonresponders declined to 14% of baseline during interferon treatment but increased to pretherapy levels after treatment. DNAp values generally paralleled HBV DNA values, but DNAp activity showed more variability and lower sensitivity than did the hybridization assay results. HBeAg values varied independently of HBV DNA and DNAp with a much delayed decline in responders. These results indicate that HBV DNA, when measured quantitatively by a sensitive solution hybridization assay, is an early predictor of the effects of antiviral agents on replication.     

Gender-related cytokine patterns in sera of schistosomiasis patients with Symmers' fibrosis

Cytokine levels were compared between schistosomiasis patients affected by intense fibrosis defined by ultrasound examination and graded from F-0 to F-3. The concentrations of interleukin-1beta (IL-1beta), IL-4, IL-5, IL-10, IL-13, gamma interferon, and tumor necrosis factor alpha (TNF-alpha) were determined by enzyme-linked immunosorbent assay of serum samples. Levels of IL-4, IL-5, and TNF-alpha in the sera of F-3 patients were significantly higher than those found in F-0 individuals, while levels of IL-13 were lower. Levels of IL-4, IL-5, and TNF-alpha in serum were significantly higher in F-3 males than in F-0 males or F-3 females. Conversely, levels of IL-13 were significantly lower in F-3 females than in F-0 females and males.     

Liposomes as immunological adjuvants in eliciting antibodies specific to the synthetic polypeptide poly(LTyr,LGlu)-poly(DLAla)–poly(LLys) with high frequency of site-associated idiotypic determinants

The antibody response to the synthetic polypeptide, poly(LTyr, LGlu)-poly(DLAla)–poly(LLys), [(T, G)-A–L], injected entrapped in liposomes which served as adjuvant, has been analyzed. The liposomes used were composed of phosphatidylcholine, cholesterol, dicetylphosphate and DL α-tocopherol (molar ratios as 4:3:0.1:0.5) and therefore, were negatively charged. Since the (T, G)-A–L is also negatively charged, no free complexes were formed. The (T, G)-A–L was found to be entrapped inside the enclosed volume of the liposomes, and no (T, G)-A–L antigenic determinants could be detected on the liposomal membranes. Injection of high-responder C3H.SW (H-2^b) mice with (T, G)-A–L-bearing liposomes demonstrated that the i.p. and the i.v. routes of immunization were efficient in eliciting (T, G)-A–L-specific antibodies, whereas the i.d. injection led to poor antibody responses. The latter route of immunization is the most effective when (T, G)-A–L is injected in complete Freund's adjuvant (CFA). When low doses (0.1 and 1 μg) of (T, G)-A–L were used for immunization, the liposomes were better adjuvants than CFA. The effectiveness of the liposomes as immunological adjuvants was also shown in their ability to induce high-potential, primed memory cells. The pattern of low (H-2^{k, a}) and high (H-2^b) responsiveness to (T, G)-A–L was retained following immunization with (T, G)-A–L entrapped in liposomes, as tested in two pairs of congenic strains. (T, G)-A–L-specific antibodies induced by injection with 1μ antigen entrapped in liposomes bear the (T, G)-A–L site-related idiotypic markers of C3H.SW (Igh-1^a) mice in a significantly higher frequency than the homologous idiotypes, namely the antibodies elicited in this strain against (T, G)-A–L in CFA. Thus, liposomes may serve as adjuvants for the production of relatively restricted (T, G)-A–L-specific antibodies of high qualitiy.