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Biomedical subjects

R Gu

Publications and source records attributed to R Gu.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Laboratory diagnosis of autoimmune sensorineural hearing loss with modified western blotting method].

Anti-membranous labyrinth proteins antibody were tested in suspectable autoimmune sensorineural hearing loss (ASNHL) with a modified western blotting method. 5 strongly positive bands (including 68,000) existed in at most 18 of 25 cases (72%). This method was found to be more sensitive than the routine one (40%). Anti-membranous proteins of Klebsiella pneumoniae antibodies were also found in 7 of 9 tested patients.

Adolescent↗
PubMed1995

[The morphologic changes of outer hair cells induced by hypotonic, hypertonic medium and electromotility].

For further understanding of biological features of cochlear outer hair cells, outer hair cells were isolated from guinea pig cochlea with micromechanical method and observed when the microosmotic concentration of their culture medium were changed. Outer hair cells shortened 3.14 +/- 0.76% (P < 0.01) within one minute after the osmotic concentration of the medium decreased to 280 mmol/L, accompanied with increase of cell diameter. Elongation of 3.34 +/- 1.09% (P < 0.05) of outer hair cells were observed after osmotic concentration of the medium was increased to 320 Os mmol/L, accompanied with decrease of cell diameter. Oscillatory elongation and shortening of outer hair cells and oscillatory displacements of intracellular organelles could be observed when square wave electrical potentials were applied across isolated outer hair cells. Hypertonic high potassium medium (K+ 100 mmol/L, 320 Osmmol/L) decreased the oscillatory movement of the cells by about 43.14% (negative potential) and 46.17% (positive potential) (P < 0.05). The shape of outer hair cells restored when the medium was isotonic. The mechanism and biological bases of outer hair cell movement were discussed.

Animals↗
PubMed1994

Structure and expression of the human T-cell leukemia virus type 1 envelope protein.

The structure and expression of the HTLV-1 envelope protein was examined using T lymphoid cell lines infected with HTLV-1 and recombinant vaccinia viruses expressing the HTLV-1 envelope. Pulse-chase experiments demonstrated that the envelope precursor, gp62, had a half-life of 7-12 hr. N-glycosylation of the precursor protein was examined using tunicamycin and endoglycosidase H. These studies revealed that at least four and possibly five potential N-glycosylation sites were utilized. In addition, the envelope precursor was found to sediment on sucrose gradients as high-molecular-weight complexes, in positions consistent with the formation of dimers and smaller amounts of higher multimeric forms. Finally, the recombinant vaccinia system was used to express mutants designed to analyze the role in HTLV-1 envelope processing of the cytoplasmic tail and the membrane-spanning domain.

Base Sequence↗
PubMed1994

[Immunohistochemical study of the olfactory mucosa and vomeronasal organ in rat, guinea pig and human fetus].

Immunohistochemical examination for neuron-specific enolase (NSE), S-100 protein and cytokeratin (CK) was performed in the olfactory mucosa and Jacobson's vomeronasal organ of rat, guinea pig and human fetus. The results indicated that: 1) The combined immunohistostaining used in this study made it possible to examine the normal morphology and pathology of the olfactory mucosa; 2) The NSE immunoreactivity was recognized in the Jacobson's vomeronasal organ of the adult rats and guinea pigs. The vomeronasal organ of human fetuses below 5 months showed positive immunoreactivity for NSE, but the NSE immunoreactivity of the vomeronasal organ in fetuses above 7 months was not confirmed. So we conclude that human vomeronasal organ is possibly a regressive organ. It is unlikely to have any olfactory function as it does in rodent animals.

Animals↗
PubMed1994

[Relationship between summating potentials and perilymphatic fistula].

Serial electrocochleogram (ECochG) recordings were obtained within 24 hours from 40 guinea pigs with experimentally induced PLF, and the cochlears of 30 guinea pigs (60 ears) were histopathologically observed under light microscope. -SP occurred in 100% experimented ears within 1-3 hours after PLF, but distention of Ressner's membrane was found only in 30% ones. CAP thresholds and N1 latencies of 10 animals were improved, accompanying disappearance of -SP in 6 of the 10 animals in 24 hours after PLF. It is presumed that -SP is not a specifically electrophysiologic indicator of ELH, and that the generation of -SP may chiefly result from reversible damage of cochlear hair cells. The mechanical factor of basilar membrane displacement can hardly be considered as a main cause of SP abnormality. The mechanism of the ELH following PLF was also discussed.

Animals↗
PubMed1994

[Study of topographic mapping of the auditory middle latency response in the guinea pigs].

Topographic mapping techniques were applied to study the auditory middle latency response (MLR) in 10 awake guinea pigs. Fourteen holes (1mm in diameter) were drilled through the skull regions and epidural electrodes were fixed on the skull with the dental cement, then auditory MLR were recorded with 13 electrodes, and MLR brain maps were obtained with a concerto system. Our result supports the hypothesis of multiple MLR generators. The main components are wave A, wave B and wave C. The foci localise the temporal lobe contralateral to the stimulated ear. The other components are wave M- and wave M+. The foci localise parietal and occipital lobes. Each wave responds differently to procaine. The result suggests that wave A, wave M- and wave M+ are generated from the subcortex, while wave B, wave C generated from the cortex.

Acoustic Stimulation↗
PubMed1994

[The embryonic development of the ostiomeatal complex from 8 to 40 weeks].

The embryonic development of the ostiomeatal complex from 8-40 weeks was studied under the light microscope. From our observation, the uncinate process was visible on the laterosuperior portion of the inferior turbinate at 8 week's gestation. By 12 weeks, the ethmoid bulla was first identifiable on the lateral wall of the middle meatus. The primordial ethmoidal infundibulum and primordial maxillary sinus were seen developing lateral to the uncinate process in the middle meatus. The air cells of the middle turbinate may be normal development of the ethmoidal labyrinth. Congenital nasal septum deviation may cause malformation of the ostiomeatal complex.

Embryonic and Fetal Development↗
PubMed1994

Computer-aided three-dimensional reconstruction and measurement of bony and membranous labyrinth.

We used three methods to reconstruct a same bony and membranous labyrinth by an image processing work station (IPWS). Three dimensional (3-D) models of the bony and membranous labyrinth were thus obtained. Different parts of the labyrinth were measured and the spatial relationship between the bony and membranous labyrinth was observed. Many 3-D parameters such as cochlear length, volume of different parts of the labyrinth, angles among the three semicircular canals were measured. The results of this experiment are useful in the study of the cochlear and vestibular function.

Ear, Inner↗
PubMed1994

The cartilaginous nasal capsule and embryonic development of human paranasal sinuses.

Embryology is of importance to the surgeon both for the study of human developmental anatomy and for the analysis of congenital conditions resulting from malformed or arrested development. The embryonic development of the nose, and especially of the paranasal sinuses, is not yet fully understood. This histologic study of 23 fetal heads aged from 8 to 40 weeks of gestation demonstrates that all four pairs of paranasal sinuses are developed from the cartilaginous nasal capsule. The outpouching of the nasal mucous membranes is only a secondary phenomenon, rather than the primary force. This observation helps to elucidate the following clinical observations: (1) the association of maxillary sinus hypoplasia with hypoplasia of the uncinate process, (2) the origin of chondrosarcoma of the maxillary bone, and (3) pneumatization of the paranasal sinuses.

Cartilage↗
PubMed1993

Role of HIV-1 envelope V3 loop cleavage in cell tropism.

The envelope protein is an important determinant of HIV-1 cell-specific tropism. The gp160 envelope precursor proteins from macrophage-tropic or T lymphoid cell line-tropic strains of HIV-1 were expressed in recombinant vaccinia virus-infected cell lines or primary lymphocytes or macrophages. No significant differences in the kinetics of synthesis of gp160, processing into gp120 and gp41 proteins, N-linked glycosylation, or release of gp120 into the medium were noted with the different envelope proteins. However, gp120 envelope protein shed into the medium was found to be at least partially cleaved at a site within the V3 loop. The gp120 envelope proteins from macrophage-tropic isolates exhibited lower rates of cleavage than those from lymphoid cell line-tropic strains in all cell types examined. Cell-free protease digestion studies also demonstrated relative resistance of the envelopes from macrophage-tropic compared to lymphoid cell line-tropic strains. All recombinant envelope proteins were recognized by monoclonal antibodies directed at gp41 or the C-terminal gp120 epitopes, and no differences in binding to CD4 were noted.

Amino Acid Sequence↗
PubMed1993

Techniques for isolating hair cells from guinea pig cochlea.

Isolated live hair cells are important models for studies on the electrophysiology, pathology and pharmacology of the hair cell. Using mechanical isolation method after papain treatment, 70 +/- 27 hair cells, including 0 to 4 inner hair cells, could be obtained from each cochlea of 4 guinea pigs. The criteria for a good viability of isolated cochlear hair cells were: 1) a smooth hair cell membrane; 2) hair cells not swollen; 3) the nucleus in normal position; 4) the cytoplasm in a state of translucence with a halo at the periphery (birefringence); and 5) no Brownian movement of the organelles within the cytoplasm. With short-term culturing at room temperature, approximately 90% of the isolated hair cells retained a good viability at the end of two hours. Subsequently, the hair cells gradually degenerated but still, at the end of five hours, about 40% of them appeared intact. The degeneration patterns have been carefully observed and described.

Animals↗
PubMed1992

Hearing impairment in diabetics.

Bekesy audiometry, impedance audiometry with stapedius reflex test, speech discrimination and the recording of electrocochleography (ECochG) and brain stem auditory evoked potentials (BAEP) were performed in 43 diabetics and 43 strictly sex- and age-matched nondiabetic controls. The results revealed that the average pure-tone thresholds, subjective click threshold and AP reactive threshold were significantly elevated in the diabetics. The average speech discrimination maximum score was significantly decreased in the diabetics. The diabetic hearing impairment was characterized by high frequency sensorineural hearing loss. Both the cochlear and retrocochlear pathology existed in the diabetics with hearing impairment.

Acoustic Impedance Tests↗
PubMed1992

[Central low frequency hearing loss].

Sixteen central hearing loss cases were studied. The typical clinical findings were bilateral low frequency loss, low speech discrimination score, abnormal ABR, predominant-SP, normal EOAE, and normal 40Hz AERP. The possible etiological factor and site of the lesion were discussed.

Adolescent↗
PubMed1990

[Dissolution of metronidazole stilus].

Metronidazole stilus is a new preparation to be inserted into periodontal pockets for treatment of periodontitis. The certificate and file number of approval given to this new product were issued by the Ministry of Public Health in August, 1989. Its shape looks like a toothpick and the width, thickness and length are 1.5mm, 0.7mm and 3 cm, respectively. The content of metronidazole in each cm of the stilus is 2.2 mg. We have studied the dissolution of the new preparation by rotation basket method. The kinetic process of dissolution approximates first order kinetics. The K, t0.5 and t0.9 are 0.0624 min-1, 12.8 and 38.6 minutes, respectively. The requirement is that the dissolved percentage should not be lower than 60% of the added amount in 30 minutes. In order to have a dissolution test similar to that of the stilus in dental pockets, we examined the dissolution in static condition. The results showed that a very high dissolution rate appeared in the beginning, but it decreased quickly, and 71.76% of metronidazole was not dissolved until 48 hours. So one insertion per two days for clinical use is suggested.

Metronidazole↗