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D Ni

Publications and source records attributed to D Ni.

At least 37 records · Page 2Linked to original sources

[Effect of monaural cochlear ablation on cell areas of ventral cochlear nucleus neurons in neonatal and adult guinea pigs].

The changes of the cross-sectional areas of anteroventral cochlear nucleus (AVCN) and posteroventral cochlear nucleus (PVCN) were studied in neonatal and adult guinea pigs after monaural cochlear ablation with computer imaging analysis system. The cross-sectional areas of neurons in AVCN and PVCN were not significantly changed after 24 h of monaural cochlear ablation in neonatal guinea pigs. But the cell areas of AVCN neurons of ablated side were respectively reduced by 20.93%, 25.70% and 28.72% compared to non-ablated side in 4 d, 7 d, 60 d after cochlear ablation, the cell areas of PVCN neurons were reduced by 17.58%, 20.30% and 38.55% respectively. The area reduction of AVCN and PVCN neurons of ablated side in 60 d group with monaural cochlear ablation were 51.00% and 32.75% relative to normal control group. Our results showed that cochlear ablation could results in rapid cell area reduction of VCN neurons in guinea pigs. Our investigation implied that it is important to stimulate the auditory nerve early in the patients with hearing loss.

Animals↗

[Employing deconvolution method for correcting scatter in radiography].

It is well known that the scattered-radiation (SR) results in degradation of the images contrast in digital X-ray radiograph. The main reason affecting radiographic image quality is the SR arising from interaction of the photons with object being radiographed and veiling glare from detector system in the II-TV chai imaging system. With the aim of improving the image quality, we employed the Gaussian function to approximate the scattered point spread function (PSF) and determined the fraction of SR, rho and the parameter, sigma experimentally on an individual system; then we built an inverse filter to process the digital chest X-ray images, which were acquired with the same system and transformed in 2-D Fourier tansform operation. The images processed were corrected by using a variable weihting factor and the resulting images are shown in this paper. The method provides a useful way for solving the problem of correction of the SR in digital X-ray images.

Algorithms↗

A disease-related rheumatoid factor autoantibody is not tolerized in a normal mouse: implications for the origins of autoantibodies in autoimmune disease.

We have analyzed B cell tolerance in a rheumatoid factor (RF) transgenic mouse model. The model is based on AM14, a hybridoma, originally isolated from an autoimmune MRL/lpr mouse that has an affinity and specificity typical of disease-related RFs from this strain. AM14 binds to immunoglobulin (Ig)G2a of the "a" allotype (IgG2aa) and not to IgG2ab. Thus, by crossing the transgenes onto an IgHa (BALB/c) background or to a congenic IgHb (CB.17) background, we could study the RF-expressing B cells when they were self-specific (IgHa) or when they were not self-specific (IgHb). These features make the AM14 model unique in focusing on a true autoantibody specificity while at the same time allowing comparison of autoreactive and nonautoreactive transgenic B cells, as was possible in model autoantibody systems such as anti-hen egg lysozyme. Studies showed that AM14 RF B cells can make primary immune responses and do not downregulate sIgM, indicating that the presence of self-antigen does not induce anergy of these cells. In fact, IgHa AM14 transgenic mice have higher serum levels of transgene-encoded RF than their IgHb counterparts, suggesting that self-antigen-specific activation occurs even in the normal mouse background. Since AM14 B cells made primary responses, we had the opportunity to test for potential blocks to self-reactive cells entering the memory compartment. We did not find evidence of this, as AM14 B cells made secondary immune responses as well. These data demonstrate that a precursor of a disease-specific autoantibody can be present in the preimmune repertoire and functional even to the point of memory cell development of normal mice. Therefore, immunoregulatory mechanisms that normally prevent autoantibody production must exert their effects later in B cell development or through T cell tolerance. Conversely, the data suggest that it is not necessary to break central tolerance, even in an autoimmune mouse, to generate pathologic, disease-associated autoantibodies.

Adoptive Transfer↗

[The analysis of abnormal auditory brainstem responses].

The abnormal auditory brainstem responses (ABR) of 56 cases who had different retrocochlear disorders were analysed. These disease included acoustic neuroma, glioma, cholesteatoma, astrocytoma, meningoma in cerebellopontile angle (CPA), chromaffin tumor of jugular foramen, intracranial metastatic tumor, demyelinating disease, multiple cranial nerve paralysis, hepatolenticular degeneration, other CPA tumors, expansion or stenosis of internal auditory meatus (IAM), and so on. The ABR features were varied in these diseases, even in same disease. In general, the wave latencies and interwave periods prolonged in the disorders which occupied place in CPA, the differentiation of wave was not clear and/or the wave was not well repeated in the disorders which spreaded all over the brain. The cause of abnormal ABRin which CT and/or MRI were normal was also analysed. The ABR detection is a sensitive indication in retrocochlear lesions.

Cerebellar Neoplasms↗

[Role of area postrema on DOCA-salt induced hypertension in rat].

OBJECTIVE: To determine the effect of area postrema AP on DOCA-salt induced hypertension in rat, with emphasis on renal hemodynamics. METHOD: Blood pressure, salt and water balances and renal hemodynamics were observed in AP ablated and sham-operated rats treated with DOCA-salt. RESULTS: In AP intact (API) rats, after one week of DOCA-salt treatment BP began elevating to statistical significance at the end of the second week (MAP 15.9 +/- 0.7 vs. 13.5 +/- 0.5 kPa), followed by a plateau period from the third to fifth week. In AP ablated (APX) rats, BP raised during the first week of DOCA-salt treatment. However, the elevation gradually disappeared and BP returned to baseline at the fifth week. Sodium balance study showed that DOCA-salt treatment induced significant sodium retention in API rat, while the sodium metabolism remained stable in APX group except in the first week. Basal renal hemodynamic parameters (GFR, RPF, UNaV, UV) were not changed at neither the beginning nor the end of the study. However, a small dose of hypertonic saline (7% NaCl 0.3 ml) injection caused a brisk rising of these four parameters in APX but not API group. CONCLUSION: AP plays an important role in normal salt and water metabolism and might be involved in pathogenesis of DOCA-salt hypertension through regulation for renal hemodynamics and body fluid homeostasis.

Animals↗

Determination of platinum in human blood using inductively coupled plasma atomic emission spectrometry with an ultrasonic nebulizer.

A rapid and accurate method for the determination of platinum in human plasma by using inductively coupled plasma atomic emission spectrometry with an ultrasonic nebulizer is proposed. The emission lines at 214.423 and 265.945 nm were investigated showing that the 214.423 nm line is the most sensitive and reliable for measuring platinum concentrations of as little as 20 micrograms l-1 (ppb) in biological materials. Microwave digestion for mineralizing human blood sample matrices was used and the possible influence of the concentration of HNO3 on platinum emission lines was investigated. Finally, the platinum concentration was determined in whole human blood, in platelets and in other blood components. Two equivalent methods for the isolation of protein from the platelet-poor plasma were investigated. The proposed method offers relative simplicity of sample pre-treatment and lends itself to various routine biological studies.

Blood Platelets↗

Interferon-alpha 2 variants in the human genome.

Variants of human leukocyte interferon alpha 2 (IFN-alpha 2a, alpha 2b, and alpha 2c) differ from each other by changes in their coding regions at nucleotide positions 137 and 170. As a result of these nucleotide variations, the DNA sequences of the three variants can be distinguished by selective restriction enzyme analysis. Human genomic DNA obtained from over 28,000 normal healthy individuals was used as templates in the polymerase chain reaction (PCR) to amplify the human IFN-alpha 2 gene sequence. The resulting PCR products were analyzed with restriction nucleases to identify the specific IFN-alpha 2 variant sequences present in the genomic DNA of the population examined. The results show that IFN-alpha 2b was detected as the predominant species and IFN-alpha 2c as a very minor species (< 0.1%). The IFN-alpha 2a gene was not detected in this population.

Alleles↗

[An experimental study of middle ear implantable hearing device].

The partially middle ear implantable hearing device was designed and tested in 7 cats with conductive hearing loss and 5 cats with mixed hearing loss. It was composed of sound processor, connector and ossicular vibrator. The ossicular vibrator was made from piezoelectric ceramic bimorph which was constructed in the form of flat chip 6mm in length, 1mm in width and 0.5mm in thickness. The incus of cat was removed and the lip attachment of the vibrator was attached to the head of the stapes. The base of the vibrator was fixed to the bone wall of bulla with medical glue. The average values of the response threshold of ABR evoked by click via this vibrator got reduction of 37dB and 39dB respectively in conductive hearing loss group and mixed hearing loss group. The gain curve of hearing was flat in the range from 0.5 to 8kHz frequencies. The ABRs evoked by click via ossicular vibrator was similar to that recorded preoperatively in the wave shape. This result indicates that this device is a highly efficient sound conducting divice to inner ear.

Animals↗

The role of B cells in lpr/lpr-induced autoimmunity.

The primary roles of T cells and B cells in the initiation of systemic autoimmunity are unclear. To investigate the role of B cells, we crossed the "Jh knockout" mutation onto the autoimmune lpr/lpr background. Animals homozygous for both traits were obtained. As expected, these animals lack B cells. These animals also show no signs of autoimmune kidney destruction nor vasculitis, in spite of carrying the lpr/lpr mutation. In contrast, lpr/lpr littermates that had B cells had severe nephritis and vasculitis, as well as autoantibodies. These results demonstrate a primary role for B cells and/or (auto)antibodies in initiating several types of autoimmune-mediated tissue destruction. The implications of this finding for models and therapy of autoimmunity are discussed.

Animals↗

[Bleeding and complications related to hemorrhage during transsphenoidal removal of pituitary tumor].

450 cases who undertook the transsphenoidal removal of pituitary tumors from 1982 to 1992 were reviewed. The bleeding during operation and the complications related to the bleeding were reported in 19 cases. The intercavernous sinuses were traumatized during operation in 9 cases. The possibility of abnormal dural arteries existed in 3 cases. The bleeding happened in the course of dissociation of nasal septum in 2 cases. The cause of bleeding in 3 cases were unclear. There was no much bleeding or bleeding record during operation, but postoperative bleeding complications appeared in other 2 cases. Heavy bleeding came from nose repeatedly in 2 cases, one of which was confirmed as pseudoaneurysm. The postoperative subarachnoid haemorrhage in 2 cases, one blindness and one paralysis of abductor nerve happened. The causes of bleeding and complication were discussed.

Adenoma, Acidophil↗

Effect of chronic electrical stimulation on cochlear nucleus neuron size in normal hearing kittens.

Very young cochlear-implant candidates may have undetected islands of residual hearing. Would the maturation of these functioning auditory neurons be affected by chronic cochlear stimulation? This was tested by examining neuron sizes in the cochlear nuclei of young, normal hearing kittens with and without chronic cochlear stimulation. Six animals received bilateral intra- or extracochlear implants and were electrically stimulated unilaterally for periods of 1,000-1,500 hours. After sacrifice, cross-sectional areas of approximately 11,000 neurons somata in the cochlear nuclei were measured with an image-analysis system. There were statistically significant differences between stimulated and unstimulated nuclei, especially the posteroventral cochlear nucleus (PVCN), in individual cats, but the directions of the differences were inconsistent. Overall, there was no significant effect of electrical stimulation on soma size. These results indicate that chronic electrical stimulation of the auditory nerve has no positive or negative trophic effects on otherwise innervated, maturing cochlear nucleus neurons.

Animals↗

[Cochlear histopathological changes following chronic extracochlear electrical stimulation in kittens].

Histopathological investigation of the cochlea following chronic extracochlear electrical stimulation was carried out in 5 kittens. The auditory nerves were electrically stimulated with round window or tympanic promontory electrodes for periods of 1276-1526 h using charge-balanced biphasic current pulses at charge densities of 1.27-5.73 microC/cm2. geom. phase. The histopathological changes were examined with a light microscope. The findings were as follow: 1. The fixations of round window and tympanic promontory electrodes were very firm. Six round window membranes became thicker in the area which contacted the electrode. One was pushed into the scala tympani and adhered to the spiral lamina of the hook region. 2. There was some outer hair cell loss, mild inner hair cell loss and disappearance of Corti's organ structures in a small area of lower basal turns. 3. Decrease of spiral ganglion cell density was found over a 2% basilar membrane length in 2 stimulated cochleas. 4. There was no change in normal control cochleas. These results indicate that mild histopathological changes occurred even though chronic electrical stimulation was performed with non-invasive extracochlear electrodes. The mechanism behind these changes should be further investigated.

Animals↗

Cochlear pathology following chronic electrical stimulation of the auditory nerve. I: Normal hearing kittens.

The present study examines the histopathological effects of long-term intracochlear electrical stimulation in young normal hearing animals. Eight-week old kittens were implanted with scala tympani electrode arrays and stimulated for periods of up to 1500 h using charge balanced biphasic current pulses at charge densities in the range 21-52 microC cm-2 geom. per phase. Both click and electrically evoked auditory brainstem responses were periodically recorded to monitor the status of the hair cell and spiral ganglion cell populations. In addition, the impedance of the stimulating electrodes was measured daily to monitor their electrical characteristics during chronic implantation. Histopathological examination of the cochleas showed no evidence of stimulus induced damage to cochlear structures when compared with implanted, unstimulated control cochleas. Indeed, there was no statistically significant difference in the ganglion cell density adjacent to the stimulating electrodes when compared with a similar population in implanted control cochleas. In addition, hair cell loss, which was restricted to regions adjacent to the electrode array, was not influenced by the degree of electrical stimulation. These histopathological findings were consistent with the evoked potential recordings. Finally, electrode impedance data correlated well with the degree of tissue growth observed within the scala tympani. The present findings indicate that the young mammalian cochlea is no more susceptible to cochlear pathology following chronic implantation and electrical stimulation than is the adult.

Animals↗

[A physiological investigation of chronic electrical stimulation with scala tympani electrodes in kittens].

A physiological investigation of cochlear electrical stimulation was undertaken in six two-month-old kittens. The scala tympani electrodes were implanted and electrically stimulated using biphasic balanced electrical pulses for periods of 1000-1500h in four ears. Four ears received implants for same period but without electrical stimulation. The other two ears served as normal control. The results indicated: 1) Chronic electrical stimulation of the cochlea within electrochemically safe limits did not influence the hearing of kittens and the normal delivery of impulses evoked by acoustic and electrical signals on the auditory brainstem pathway. 2) The wave shapes of EABRs were similar to those of ABRs. The amplitudes of EABRs showed a significant increase following chronic electrical stimulation, resulting in a leftward shift in the input/output function. The absolute latencies and interwave latencies of waves II-III, III-IV and II-IV were significantly shorter than those of ABRs. These results imply that there was no adverse effect of chronic electrical stimulation on the maturing auditory systems of kittens using these electrical parameters and the mechanism of electrical hearing should be further studied.

Animals↗

[Influence of moxibustion on TXA2 and PGI2 in plasma of rat infected epidemic hemorrhagic fever virus (EHFV)].

In this paper, the model of rat infected EHFV was made and the influence of moxibustion on TXA2 and PGI2 in its plasma was observed. The results show that the content of TXA2 increased and PGI2 decreased in rat significantly after the abdominal inoculation of EHFV, and the content of TXA2 decreased and PGI2 increased markedly in rat infected EHFV to normal level after treatment with moxibustion, suggesting that the regulative function of moxibustion on TXA2 and PGI2 is one of its nerve-endocrine-immune regulations to the body, and there is an important significance. This study provides an important reference for mechanism exploration of moxibustion preventing and treating EHF.

6-Ketoprostaglandin F1 alpha↗

[Preparation of rotundine-chitosan gelled granules and their drug-release tests].

The paper described a delivery system prepared from granulation of a chitosan solution containing rotundine in a coagulating bath and examined the effects of the ratios of rotundine: chitosan, crosslinking agents and molecular weight of chitosan on the analgesic release rate. It was shown that the rotundine (56.7%)-chitosan (Mw:5.70 x 10(5) degree of deacetylation: 72.4%) gelled granules in an artificial gastroenteric juice (pH 1.0 and 7.2) have T50 of 40 and 180 min respectively, and the total release time sustained over 540 min.

Alkaloids↗