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At least 73 records · Page 4Linked to original sources
PubMed1991

Attenuation of hearing protectors at 85 dB SPL investigated by commercial "insertion gain" method.

Attenuation of hearing protectors is conventionally measured as the difference between the subject's pure-tone hearing threshold with, and without, hearing protection under free field conditions (loudspeaker) in a sound attenuated (an-echoic) room. This REAT procedure is not objective as it involves the response of a subject. The attenuation can not be measured at noise hazard levels: > 85 dB SPL. Commercial computerized "insertion gain" equipment has recently been developed to improve the individual fitting of hearing aids. By "insertion gain" method a slender silicone probe-tube connected to an outside microphone, is inserted in the ear canal, registering the sound pressure level in front of the tympanic membrane. Thus one can objectively register the sound pressure level difference (gain) obtained close to the tympanic membrane with a given hearing aid in a non-attenuated room. We wanted to study whether the same procedure could be used to assess the attenuation of hearing protectors at noise hazard levels with acceptable measurement variability. With a commercial computerized "insertion gain" equipment (IGO-HAT 1000. Madsen Electronics) we registered the "insertion loss", the difference in sound pressure level measured < 5 mm in front of the tympanic membrane for 20 consecutive sessions (fittings) in the same subject with versus without the same hearing protector. Below 6000 Hz standard deviations were remarkably low--around 2 dB--for the two protectors tested.

Acoustics↗
PubMed1981

Shuttlebox avoidance by rats using white noise intensities from 90-120 db SPL as the UCS.

Hooded rats in 4 groups (10 M, 10 F each) were given shuttlebox avoidance training, 25 trials a day for 6 consecutive days, using a compound light-click warning signal and white noise as an aversive unconditioned stimulus at either 90, 100, 110, or 120 db SPL. Avoidance performance was an inverted U-shaped function of noise level. Females were significantly more active than males at each noise level, but although females performed more avoidance responses than males at each level, this sex difference was not significant. Avoidance response latencies were relatively invariant across training sessions for each group, as were escape responses latencies for the 100- and 110-db groups. Escape response latencies for the 90- and 120-db groups increased across training sessions. Shuttlebox performance as a function of increasing white noise UCS level is, in most respects, similar to performance obtained with increasing shock intensities.

Animals↗
PubMed1996

Identification of an Spl-like element within the immunoglobulin kappa 3' enhancer necessary for maximal enhancer activity.

A number of functional DNA sequences have been identified within the murine immunoglobulin kappa 3' enhancer (kappaE3'). These DNA sequences were identified using plasmid reporter constructs in which the centrally active core region (or mutants of that region) of the enhancer was placed directly adjacent to the promoter of a reporter construct. Functional DNA sequences thus identified were found to bind to the transcription factors PU.1, NF-EM5, E2A, ATF-1, or CREM. In the studies reported here, we show that additional enhancer sequences that lie outside of the core region are necessary for maximal enhancer activity when the core region is not directly adjacent to the promoter. A series of progressive and internal deletion constructs shows that enhancer sequences between nucleotides 275 and 329 are important for enhancer activity. Progressive deletion to nucleotide position 329 resulted in a 4-fold reduction in enhancer activity. Using electrophoretic mobility shift assays, we show that this segment of the enhancer binds to ubiquitously expressed nuclear factors. Dimethyl sulfate methylation interference assays indicated protein-DNA interactions within a G-rich sequence between positions 302 and 306 and an A-rich sequence between positions 319 and 329. Ultraviolet light protein-DNA cross-linking studies revealed nuclear factors of approximately 85 and 105 kDa that bind to the newly identified enhancer region. Oligonucleotide competition studies and binding studies with purified Sp1 or Sp1 antibodies indicate that Sp1 can bind to this sequence. These studies show that functional sequences within the kappaE3' enhancer include an Sp1-like site approximately 90 bp 5' of the central 132 bp region originally believed to account for most of the enhancer activity.

Animals↗
PubMed1999

Human monoclonal antibodies isolated from spontaneous Epstein-Barr virus-transformed tumors of Hu-SPL-SCID mice and specific for fusion protein display broad neutralizing activity toward respiratory syncytial virus.

Two human monoclonal antibodies, RF-1 and RF-2, specifically recognize the fusion protein of the human respiratory syncytial virus (RSV). These were isolated from spontaneous tumors in SCID mice reconstituted with human splenocytes and boosted with fusion protein. The tumors consisted of Epstein-Barr virus-transformed human B cells in animals with antigen-specific antibody titers>105. The binding affinity of RF-1 and RF-2 to the fusion protein is 1010 and 109 M-1, respectively. The antibodies bind specifically to a conformational epitope of the fusion protein on RSV-infected HEp-2 cells. Both antibodies display virus-neutralizing properties in vitro at concentrations varying between 8 and 1000 ng/mL. Virus neutralization applies to a broad variety of wild and laboratory-adapted virus strains belonging to both virus types A and B. These antibodies are potential candidates for passive immunotherapy of severe RSV infections.

Animals↗
PubMed1984

Effects of temporal stimulus properties on perception of the [sl]-[spl] distinction.

Two studies investigated the influence of the independently varied durations of preceding and following signal portions on the amount of closure silence needed to perceive 'splash' rather than 'slash'. Increases (or decreases) in the durations of the [s] and [l] acoustic segments had opposite effects which cancelled when the silent intervals were short (experiment 1), but yielded a net effect due to [s] duration when the silent intervals were long (experiment 2). These findings, which resolve a conflict between earlier results in the literature, are interpreted as reflecting a perceptual compensation for coarticulatory shortening of [s] before stop consonants, in conjunction with (possibly psychoacoustic) contrastive interactions between the perceived durations of adjacent acoustic segments. The results suggest that local temporal signal properties, as distinct from global perceived speaking rate, are an important factor in phonetic perception.

Humans↗
PubMed1998

A subset of notch functions during Drosophila eye development require Su(H) and the E(spl) gene complex.

The Notch signalling pathway is involved in many processes where cell fate is decided. Previous work showed that Notch is required at successive steps during R8 specification in the Drosophila eye. Initially, Notch enhances atonal expression and promotes atonal function. After atonal autoregulation has been established, Notch signalling represses atonal expression during lateral specification. In this paper we investigate which known components of the Notch pathway are involved in each signalling process. Using clonal analysis we show that a ligand of Notch, Delta, is required along with Notch for both proneural enhancement and lateral specification, while the downstream components Suppressor-of-Hairless and Enhancer-of-Split are involved only in lateral specification. Our data point to a distinct signal transduction pathway during proneural enhancement by Notch. Using misexpression experiments we also show that particular Enhancer-of-split bHLH genes can differ greatly in their contribution to lateral specification.

Animals↗
PubMed2006

Myocardial infarction is associated with Spl binding site polymorphism of collagen type 1A1 gene.

OBJECTIVE: Human atherosclerotic lesions contain collagen type I, which plays a pivotal role in atherosclerotic plaque stability. In contrast, the normal coronary arteries do not express this type of collagen. Data have shown that the collagen type 1A1 (COL1A1) gene Sp1 binding site (-1245 G/T) polymorphism is associated with disturbed collagen protein production. METHODS: In our study, COL1A1 gene Sp1 polymorphism was investigated in 136 patients with myocardial infarction (MI) 5 months after the acute phase, and 212 age-matched control subjects in association with any cardiovascular risk factors (such as serum adiponectin levels, hyperinsulinaemic status, hyperlipaemia). RESULTS: The "SS" genotype of the COL1A1 gene was found to occur significantly more frequently in patients surviving a MI, as compared to the control group and the "Ss" and "ss" genotype frequencies (the presence of the s allele) were lower in our patients, than in control group. However, the occurrence of cardiovascular risk factors was significantly higher among the "s" allelic carriers as compared to patients carrying the "S" allele of the COL1A1 gene. CONCLUSION: Our results raise the possibility that COL1A1 gene Sp1 polymorphism might have an impact on the development of MI.

Adiponectin↗
PubMed1996

Comparison of probe insertion methods on estimates of ear canal SPL.

Real-ear sound pressure levels (SPLs) were compared among three methods used for positioning a probe microphone in the ear canal. The probe insertion techniques included (1) an acoustic method that incorporates use of the quarter-wave anti-resonance property of the ear to determine acoustically the location of the probe tube relative to the eardrum; (2) a constant insertion depth method (25 mm from the intratragal notch); and (3) the earmold +5-mm method, which places the probe 5 mm beyond the tip of the earmold, thereby avoiding problems associated with the transition region where sound exits from the bore of the earmold into the larger ear canal. Measurements were obtained at 32 test frequencies in 24 adults with normal middle ear impedance. Results indicated that the SPLs measured by the acoustic method were modestly higher than those measured by the other two methods. This result was most evident in subjects with long ear canals (> 25 mm) and at high test frequencies (3.0 to 6.3 kHz).

Amplifiers, Electronic↗
PubMed1982

Basal ganglia pathways to the tectum: the afferent and efferent connections of the lateral spiriform nucleus of pigeon.

Previous studies have demonstrated that the lateral spiriform nucleus (SpL) of the avian pretectum receives a major input from the ipsilateral basal ganglia (Karten and Dubbeldam, '73) and projects to the ipsilateral optic tectum (Brecha et al., '76). The present study has further detailed the anatomical organization of the afferent and efferent connections of SpL, with particular reference to (1) the sources of afferent inputs to SpL, (2) the projection targets of SpL, and (3) the laminar termination pattern of the SpL projection to the tectum. The SpL was found to receive clear-cut major inputs from only three nuclei: (1) the ipsilateral paleostriatum primitivum (PP) of the basal ganglia (the avian homologue of the mammalian globus pallidus), (2) the ipsilateral anterior nucleus of the ansa lenticularis (ALa) of the diencephalon, and (3) the ipsilateral nucleus tegmentipedunculopontinus (TPc) of the mesencephalon. Both TPc and ALa have previously been noted themselves to receive major inputs from the ipsilateral PP (Karten and Dubbeldam, '73). Two other cell groups may give rise to a slight projection to the ipsilateral SpL: (1) the posterior nucleus of the ansa lenticularis (ALp) of the diencephalon and (2) the nucleus semilunaris (SLu) of the isthmic brainstem. The ALp also receives a major input from PP (Karten and Dubbeldam, '73). Two other cell groups may give rise to a slight projection to the ipsilateral SpL: (1) the posterior nucleus of the ansa lenticularis (ALp) of the diencephalon and (2) the nucleus semilunaris (SLu) of the isthmic brainstem. The ALp also receives a major input from PP (Karten and Dubbeldam, '73), while SLu receives a major tectal projection (Hunt and Kunzle, '76a). The ipsilateral tectum was found to be the only projection target of SpL. The present data suggest that the SpL projection to the tectum is restricted to layers 8-13, with layers 11-13 receiving the heaviest projection from SpL. Among layers 8-10, layer 9 receives the lightest projection from SpL. The present results indicate that SpL receives only a limited number of inputs, which in all likelihood relay largely basal ganglia input to SpL. Since SpL projects only to the tectum, the sole function of SpL apparently is the transmission of ipsilateral basal ganglia influences to the avian optic tectum. Tectal layers 8-15 have been previously found to represent the layers of origin of the descending pathways of the avian tectum to hindbrain motor and "premotor" cell groups (Reiner and Karten, '82). In view of the purported involvement of the basal ganglia in motor functions, the basal ganglia pathway to the ipsilateral tectum via SpL may represent a major route by which the avian basal ganglia exert influences over motor functions.

Afferent Pathways↗
PubMed1997

Intravenous administration of splenocytes in early pregnancy changes the implantation window in mice.

To clarify the role of immune cells in the reproductive phenomenon during early pregnancy, we investigated the effect of splenocytes obtained from mice in early pregnancy on embryo implantation. We prepared splenocytes from 5 week old pregnant ICR mice on day 4 (pregnancy day 4 splenocytes; P4-spl) and day 8 (pregnancy day 8 splenocytes; P8-spl), from 5 week old pseudopregnant ICR mice on day 4 (pseudopregnancy day 4 splenocytes; PP4-spl) and from 5 week old di-oestrous virgin mice (di-oestrous splenocytes; Di-spl). The supernatants (P4-sup, P8-sup, PP4-sup and Di-sup) derived from the suspensions of P4-spl, P8-spl, PP4-spl and Di-spl respectively, were used in the control groups. The recipient pseudopregnant mice (6 weeks of age) were injected i.v. with splenocytes (2 x 10(7) cells) or supernatants as controls, and embryo transfer was performed on day 2. Embryo implantation was evaluated 7 days later under laparotomy. The successful implantation rate per embryo was markedly higher compared with the control groups in the P4-spl (30.5 +/- 8.55 versus 1.0 +/- 1.37%, n = 200, P < 0.01) and P8-spl (20.1 +/- 10.3 versus 1.17 +/- 1.62%, n = 200, P < 0.05) groups. On the other hand, a slight but not significant increase was observed in the PP4-spl (8.33 +/- 8.80% versus 1.5 +/- 1.37%, n = 200) and Di-spl (9.0 +/- 5.76% versus 2.3 +/- 2.28%, n = 200) groups. Among the splenocyte administration groups, the implantation rate in the P4-spl group was significantly higher than in the PP4-spl and Di-spl groups (P < 0.01). These findings indicate that i.v. administration of splenocytes can change the murine implantation window. Since the splenocytes during early pregnancy are most effective on embryo implantation, peripheral immune cells in early pregnancy may be involved in embryo implantation.

Animals↗