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Biomedical subjects

M Guo

Publications and source records attributed to M Guo.

At least 91 records · Page 5Linked to original sources
PubMed1999

[The clinic application of multichannel cochlear implant with eleven cases reported].

OBJECTIVE: To review the effects of profound sensorineural deaf patients who were implanted multichannel cochlear. METHOD: Eleven profound deaf patients (6 prelingually deaf and 5 postlingually deaf) were implanted with twenty-two (model Minisystem 22) and twenty-four (model Nucleus 24) channel cochlear. Mapping of cochlear speech processor was done in 1 to 1.5 months after operation. RESULT: All of 11 patients obtained the hearing. The patients with postlingually deaf can dialog and communicate with telephone after a simple language training without lip reading training. These patients achieved the best results, they not only stepped in sound world but also obtained a normal living and work. In the prelingually deaf patients, they got hold of incoordinate progress in speech ability after assess and speech training. CONCLUSION: The multichannel cochlear implant had good effects in profound deaf patients, especial in postlingually deaf patients and younger children.

Adolescent↗
PubMed1999

[Electrically evoked otoacoustic emissions and their distortion products in guinea pigs].

The objective of this study was to investigate micromechanical properties and electromotility of cochlear outer hair cells in vivo. Extracochlear electrically stimulation with sinusoid alternating current was delivered to cochlea of guinea pigs. Sound pressure level was recorded from ear canal by microphone and the electrically evoked otoacoustic emissions (EEOE) and their distortion products (DPEEOE) were analyzed with FFT spectrum analyzer. The EEOE in 3 kHz to 33 kHz were recorded from 15 guinea-pigs in 18 guinea-pigs, the transfer function was more smooth in 8 kHz to 31 kHz. The DP EEOE were very clear when F1 = 6 kHz, F2 = 7.2 kHz, and the current intensity higher than 100 microA. While the intensity increased to 300 microA, two distortion products, F2-F1 and 2(2F1-F2)-F1, could be seen in addition to 2F1-F2. The input-output function showed that EEOE and DP EEOE I/O function were linear when lower electric intensity stimulation was given, but they displayed compress non-linear features when higher intensity current was delivered. The authors conclude that EEOE and DP EEOE are expression of electrophonic hearing characteriged by wide frequency bandpass appearance, wide dynamic range and non-linear features, so they are good tools for studying the mechanical properties of outer hair cells and the integrate function of Corti's organ.

Animals↗
PubMed1999

[Report of myringoplasty with interlay method in 53 ears perforation of tympani].

OBJECTIVE: To probe into an eutherapeutic method for the healing tympanic membrane aperture. METHOD: Fifty-three cases of tympamic membrane aperture were treated with myringoplasty of interlay method. The results were compared with that of underlay method of 168 ears in same period. RESULT: The rate of closure of perforation of tympani was 96.2% in interlay method group and 85.7% in underlay method. The hearing recovery of interlay method group was better than underlay method group. Function of Eustachian tube kept good condition in interlay method group. There was no blunting of anterior tympanomeatal angle in the interlay group. CONCLUSION: The interlay method of myringoplasty is an ideal method for healing perforation of tympani.

Adolescent↗
PubMed1999

[The effects of substance P antibody on tuning curve of auditory evoked potential of cochlear nucleus and inferior colliculus in guinea pigs].

OBJECTIVE: To explore the effects of substance P on the frequency analysis of sound signals in the auditory brainstem. METHODS: The electrodes were implanted into the cochlear nucleus (CN) and the inferior colliculus (IC) of guinea pigs. The auditory evoked potential in CN (CN-AEP) and IC (IC-AEP) was recorded with tone pip stimulation and tone burst forward masking techniques. The Q10 dB values of the tuning curves were compared between the CN-AEP and IC-AEP after injection of SP antibody or rabbit serum with the same dosage (used as control) into the nucleus. RESULTS: After injection of SP antibody, the Q10 dB values of the tuning curves of CN-AEP and IC-AEP had no significant changes in 1 kHz and 2 kHz probe tone groups. When probe tone frequencies were 4 kHz and 6 kHz, there was a significant difference between the two frequency groups in Q10 dB. In addition, the higher frequency slope and lower frequency slope value had corresponding changes. CONCLUSION: The results imply that SP could act as a neuromediator in the auditory afferent system and participated in the high frequency analysis in the auditory brainstem.

Acoustic Stimulation↗
PubMed1998

Solid-phase stereoselective synthesis of 2'-O-methyl-oligoribonucleoside phosphorothioates using nucleoside bicyclic oxazaphospholidines.

The use of 2'-OMe-ribonucleoside bicyclic oxazaphospholidines derived from (R)- or (S)-2-pyrrolidinemethanol has enabled the stereoselective synthesis of (Rp)-, and (Sp)-2'-O-methyloligoribonucleoside phosphorothioates. Interestingly, higher stereoselectivity (96-98%) was observed in the synthesis of (Sp)-2'-O-methyl-oligoribonucleoside phosphorothioates compared to that in the case of (Sp)-oligodeoxyribonucleoside phosphorothioates (90%).

Chromatography, High Pressure Liquid↗
PubMed1998

Fine needle aspiration biopsy of the penis: transitional cell carcinoma of the urinary bladder with mucinous differentiation.

We report a case of transitional cell carcinoma of the urinary bladder metastatic to the penis. The diagnosis was established by fine needle aspiration biopsy (FNAB). Malignant cells showed mucinous differentiation. Ancillary studies carried out in the FNA material as well as in the primary bladder carcinoma suggested transitional cell carcinoma with mucinous differentiation. FNAB proved to be effective in diagnosing a secondary neoplasm to the penis. Mucoid differentiation of urothelial cells can be seen in FNAB specimens and might pose a problem in differential diagnosis.

Biopsy, Needle↗
PubMed1998

Decreased citrate improves iron availability from infant formula: application of an in vitro digestion/Caco-2 cell culture model.

We have applied an in vitro digestion/Caco-2 cell culture model to the assessment of iron availability from human milk and a generic cow's milk-based infant formula. Experiments were designed to determine the availability of iron from human milk relative to infant formula and whether known promoters of iron absorption would increase Caco-2 cell iron uptake and availability from the infant formula. In addition, we sought to determine if decreasing the citrate concentration in the infant formula would increase the iron uptake. Although approximately twice as much iron was in solution from digests of the infant formula relative to that of human milk, smaller or equal amounts of iron were taken up from the infant formula relative to the human milk digest. These results are qualitatively similar to in vivo studies. Addition of known iron uptake promoters to infant formula did not enhance Caco-2 cell iron uptake from the infant formula digest, indicating that the iron in the infant formula existed predominantly in a tightly bound unavailable form(s). Enzymatic pretreatment of the infant formula with citrate lyase and oxalacetate decarboxylase decreased the citrate concentration by 67% and resulted in a 64% increase of iron in solution, which corresponded to a 46% increase in the cell iron uptake. Iron uptake from the "low citrate" formula plus cysteine was 102% greater relative to the nontreated formula. The results indicate that too much citrate can reduce iron uptake, particularly if it is present at concentrations greater than promoters such as ascorbic acid and cysteine.

Animals↗
PubMed1998

Electrocardiographic Changes and Mortality Due to Myocardial Infarction in Rats With or Without Imidapril Treatment.

BACKGROUND: Various angiotensin-converting enzyme inhibitors are known to improve heart function and prolong survival in patients and animals after myocardial infarction. Because myocardial infarction is known to induce arrhythmias, this study tested the hypothesis that early treatment with the angiotensin converting enzyme inhibitor imidapril reduces mortality during acute myocardial infarction because of protective effects against arrhythmogenesis. METHODS AND RESULTS: Rats were randomly divided into four groups: sham control, myocardial infarction, sham plus imidapril, and myocardial infarction plus imidapril. Myocardial infarction was produced by ligation of the left anterior descending coronary artery. Treated rats received imidapril (1 mg/kg/day) through a gastric tube beginning 1 hour after coronary occlusion; control rats received tap water. Electrocardiogram (ECGs) were recorded 1, 3, 7, and 21 days postocclusion. Infarct size and scar weight were determined at 21 days in the myocardial infarction groups with and without imidapril treatment. ECGs of untreated rats showed ST-segment changes, abnormal Q waves, premature ventricular complexes, and QT(c) prolongation 1-21 days after coronary occlusion. Total mortality in 21 days averaged 35% in untreated rats; mortality within 48 hours was 30%. On the other hand, imidapril-treated rats showed fewer ST-segment changes, fewer abnormal Q waves, and a decreased incidence of premature ventricular complexes after coronary occlusion; the ST-segment and QT(c) interval returned to basal values within 1 week after occlusion. Imidapril treatment did not affect the ECG pattern in sham-treated control animals. Total mortality in the imidapril-treated group in 21 days after infarction was 22.5%; mortality within 48 hours was 20% (P <.05 compared with the untreated infarction group). Infarct size and scar weight caused by coronary occlusion did not differ in the untreated and imidapril-treated groups. CONCLUSIONS: Early treatment with imidapril markedly decreases mortality in rats after acute myocardial infarction. The lower mortality is not associated with a decrease in infarct size but is consistent with a protective effect of the drug against arrhythmogenesis.

Journal Article↗
PubMed1998

[Studies on cloned genomic differential DNA fragments extracted from esophageal carcinoma and non-cancerous esophageal tissues in Linxian County].

OBJECTIVE: To isolate the genes involved in carcinogenesis of esophageal cancer and to provide a molecular marker for screening and early detection of it in susceptible individuals. METHODS: DNA extracted from 12 matched pairs of esophageal cancer and non-cancerous tissues in patients of Linxian County, Henan Province, a high incidence area for esophageal cancer, and differential DNA fragments were isolated with arbitrary primer polymerase chain reaction (AP-PCR), cloned and sequenced. Restriction endonuclease Dra I and Hind III were used to digest genomic DNA in the pair-matched cancerous and non-cancerous esophageal tissues for Southern blot analysis. RESULTS: There was a randomly amplified differential DNA fragment of about 1.0 kb in cancerous tissues in three of the twelve cases with esophageal cancer, but no such fragments could be found in corresponding non-cancerous tissues. Sequence analysis showed that no homologous DNA in GeneBank database as same as 11T differential DNA fragments. Southern blot analysis showed that there was significant difference between pair-matched cancerous and non-cancerous tissues. CONCLUSION: 11T differential DNA fragment appeared during carcinogenesis of the esophagus, and further investigations were needed to study if it could be regarded as a new kind of oncogene or a biomarker of it.

Base Sequence↗
PubMed1998

[Aberrant expression of immunoglobulin germline gene C mu in leukemias].

OBJECTIVE: To investigate the significance of immunoglobulin germline gene C mu expression in leukemias. METHODS: Immunoglobulin germline gene C mu transcripts in 63 bone marrow samples from 59 leukemia patients were examined by RT-PCR. RESULTS: Germline C mu transcripts could be identified in 17 of 26 AML, 9 of 12 ALL, 4 CML-BC and 2 CLL patients. HLA-DR was expressed in 80% C mu(+) patients and in 92.9% C mu(+) AML patients. In 10 normal bone marrow or peripheral blood samples C mu transcripts were undetectable. CONCLUSION: Leukemogenesis in most acute leukemia may originate from the common progenitors of early B-lymphoid and myeloid cells.

Acute Disease↗
PubMed1998

[Histological changes of Cysticercus cellulosae under the action of proteinase of Omphalia lapidescens in vitro].

AIM: For the purpose of finding an anthelmintic with high efficacy, low toxicity and low cost, especially from the Chinese traditional medicines. METHODS: Forty Cysticercus cellulosae were separately incubated with proteinase from artificially fermented Omphalia lapidescens for 2 h, 4 h and 8 h, and then examined for histological changes by light microscopy and compared with those of proteinase from natural dry Omphalia lapidescens after similar treatment. RESULTS: Cysticercus cellulosae were morphologically and structurally impaired after exposure to the action of proteinase of Omphalia lapidescens, and the degree of impairment was proportionally paralleled to the duration of treatment. CONCLUSION: The anti-cysticercus effect of proteinase of Omphalia lapidescens and the homogeneity of proteinases from artificially fermented and natural Omphalia lapidescens were confirmed.

Animals↗
PubMed1998

[Establishment of hybridoma secreting anti-mycobacteria monoclonal antibody by using electrofusion technique].

By using the electrofusion technique, the fusion of NS1 myeloma cells with spleen cells of BALB/c mouse immunized with five species of mycobacteria was carried out. With the optimal electrofusion conditions, we obtained a high fusion efficiency of 1.75 hybrid cell clones per 10(5) spleen cells. ELISA was used for screening secreting antimycobacteria McAb hybrid cells. After cloning, 22 stable hybrid cells lines were selected, and 8 of them had been studied.

Animals↗
PubMed1997

Basilar membrane velocity noise.

Basilar membrane (BM) noise, measured as a velocity signal under the quiet acoustic condition, was investigated in the guinea pig. The cochleas of anesthetized young healthy guinea pigs were surgically exposed and a hole was made on the lateral wall of the scala tympani of the first cochlear turn for visualization of the BM and measurement of the BM velocity with a laser interferometer. The amplitude and frequency of the BM velocity noise were analyzed by a spectrum analyzer under different conditions. The spectrum of the BM velocity noise was a band limited function with a peak velocity at the topographic best frequency of the measured location on the BM. The peak velocity ranged to about 8 microm/s and depended on the physiological condition of the cochlea. Saline blockage of the external auditory canal or the middle ear did not change the BM noise. BM noise was much smaller, or was not evident, when the cochlear sensitivity decreased. The suppression tuning curve of the BM velocity noise indicates that the maximum suppression caused by an acoustic pure tone occurred at the best frequency location. A low sound level wide band acoustic noise given to the external ear canal produced a spectrum function having the same frequency and amplitude response as the BM noise. Electrical stimulation of the crossed olivocochlear bundle significantly depresses the BM velocity noise. These data demonstrate that the BM noise is a representation of internal rather than external noise. The amplitude and frequency of the BM noise reflect the usual cochlear sensitivity and frequency selectivity. Since the organ of Corti in the sensitive cochlea is a highly sensitive and tuned mechanical system, the internal (to the animal) noise responsible for the BM noise may originate from mechanical vibrations remote from the cochlea and propagated to the ear, or may be caused by Brownian motion of cellular structures in the cochlea.

Acoustic Stimulation↗
PubMed1997

Role of the Fas/Fas ligand pathway in apoptotic cell death induced by the human T cell lymphotropic virus type I Tax transactivator.

Two distinct human diseases have been described in association with human T cell lymphotropic virus type I (HTLV-I) infection: adult T cell leukaemia and tropical spastic paraparesis/HTLV-I-associated myelopathy. Although comprehensive understanding of specific mechanisms underlying pathogenesis of either disease has not yet been achieved, the viral regulatory protein Tax is believed to play a significant role. Previous studies demonstrated the potential of Tax to transform host cells. Here, it is shown that the Tax transactivator has in addition the potential to induce T cell death by apoptosis. Using an inducible system (Jurkat cell line JPX-9), significant apoptotic cell death upon Tax expression was observed. In an attempt to detect the cellular genes mediating this effect, it was found that induction of Tax was associated with marked upregulation of the Fas ligand (FasL) gene. Tax-induced apoptosis was inhibited when the Fas/FasL pathway was interrupted by YVAD-cmk, the inhibitor of ICE-like proteases. Transient expression experiments provided additional support for the putative role of endogenous FasL in Tax-induced apoptosis. Upon cotransfection with Tax-expressing plasmid, the transcriptional activity of the FasL promoter was found to be significantly upregulated in Jurkat cells and several other cell lines, as measured by reporter gene expression. Furthermore, cotransfection using different Tax mutants demonstrated that both CREB and NF-kappaB activation domains of Tax protein were required for the transactivation to take effect.

Adult↗
PubMed1997

[Effect of platelet derived growth factor on the growth of human glomerular mesangial cells in vitro].

OBJECTIVE: To study the effect of plateletderived growth factor (PDGF) on the growth of human glomerular mesangial cells (MsC) in vitro. METHODS: Immunohistochemistry for the detection of BrdU positive cells; [3H] proline incorporation for the bioactive assay of total amount of collagen; and Northern blot analysis for the determination of fibronectin (FN) alpha 1 (IV) collagen and c-myc mRNA expression. RESULTS: The cell labelling index (LI) of BrdU incorporation in the PDGF group is 34.5% higher than that in the normal group, which was 19.5% (P < 0.01), The total amount of collagen secreted by MsC within cells and outside of cells in the PDGF group were 2.69 +/- 0.60% and 3.87 +/- 0.65% respectively, much higher than that of the normal group, which were 1.25 +/- 0.50% and 1.61 +/- 0.51% respectively (P < 0.01). Northern blot analysis revealed an increase of FN, Col IV, c-myc mRNA levels in the PDGF group. CONCLUSION: PDGF can stimulate cell proliferation, synthesis of collagen and enhance FN, Col IV, c-myc mRNA expression. It is possible that PDGF may play an important role in the development and progression of glomerulopathy.

Cell Division↗
PubMed1997

[Research on basilar membrane vibration of guinea pigs elicited by direct current pulse].

To investigate the electromotility of basilar membrane (BM) of guinea pigs in vivo, a couple of Platinum-iridium wire electrodes were placed into holes drilled in the scala vestibuli and scala tympani on the basal turn of cochlea separately. The organ of Corti was stimulated with rectangular direct current pulses. The displacement and velocity of BM were measured with Laser Doppler velocimeter. The results indicated that the displacement of BM elicited by current moved toward the scala where positive current was injected. The waveform of BM displacement was corresponding to the rectangular pulse of electric current step. Ringing responses could be seen at the onset and offset of current pulse that was the transient responses of outer hair cells. The frequency of the ringing was the same as that of characteristic frequency of partition in BM. It is supposed that the ringing of BM is an active process of depletive energy and participate with cochlear amplifier. In the insensitive cochlea or dead animal, direct current can still elicit a BM displacement but the ringing response is decreased or disappeared. This phenomenon is probably because of metabolic disturbance in damaged outer hair cells. The BM vibration induced by direct current is similar to that of induced by acoustic stimulation, which can transfer to other partition of BM by traveling wave. This characteristic has laid a foundation of electromotile hearing and electrically evoked otoacoustic emission.

Animals↗