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Biomedical subjects

M Guo

Publications and source records attributed to M Guo.

At least 127 records · Page 7Linked to original sources

[An experimental study on autoimmune sensorineural hearing loss].

In order to observe the immunological changes, an animal model of experimental autoimmune sensorineural hearing loss was created by using the guinea pig's inner ear as an antigen. The results showed that the endolymphatic hydrops and distension of the Reissner's membrane appeared in the models. Disturbance and loss of the stereocilia can also be seen. Two weeks after immunization, the mean of ABR thresholds was significantly elevated by comparing with the preimmunization (P < 0.01). The elevation of the ABR thresholds was associated with the pathological changes. After immunization, the T lymphocyte transform function was much different from that of the normal state. CIC was also elevated significantly after immunization.

Animals↗

[Inhibitory effect of heparin on glomerular mesangial cell].

The pure mesangial cells (MsC) were isolated from the culture of rat glomeruli. After identification, they were divided into heparin-treatment group and control group. It was found that heparin profoundly inhibited the growth of MsC with 75.9% inhibitory rate by means of direct counting MsC. MTT method proved that the inhibitory effect of heparin on MsC was dose-dependent. Electronmicroscopic observation revealed dilated endoplasmic reticulum and Golgi vesicles, more secondary lysosomes, prominent myelin figures and decreased microfilaments in the cytoplasm of the MsC exposed to heparin. Immunocytochemical studies showed that the amounts of FN and LM in the cytoplasm of MsC decreased after heparin treatment. Immunocytochemical investigation also confirmed that heparin could inhibit the expression of nuclear oncogene c-fos and c-jun in the MsC stimulated by PMA. The significance and possible mechanism of inhibitory effect of heparin on MsC were discussed.

Animals↗

[Surgical treatment of the bilateral abductor paralysis].

27 patients with bilateral vocal cord paralysis were treated in the First Clinical Medical College of Beijing Medical University, and all of them were followed up at least one year after treatment. According to the length of the vocal cord and the degree of the anterior angle of the thyroid cartilage, one of the three different surgical procedures would be selected to alleviate the symptoms of bilateral abductor paralysis. The width of glottic chink after treatment is the paramount index. The average estimated size of the posterior glottic chink or point of maximum width of glottic chink should be equal to or bigger than 4mm after surgical treatment. The open approach to arytenoidectomy-Woodman's Technique was performed in 15 patients, and among them the tracheal cannulas were removed in 11 cases, and 8 cases had a glottic chink bigger than 4mm width. In 9 cases with short length vocal cord and narrow anterior angle of the thyroid cartilage, a modified hemilaryngectomy was used by thyrotomical approach, and a successful result was obtained with good to excellent exercise tolerance for social activity. Unfortunately, in the remaining 3 patients, the nerve-muscle pedicle technique reinnervation of bilateral vocal cord paralysis was applied, and no patient demonstrated visible inspiratory vocal cord abduction. Although this type of operation might totally reconstruct respiratory function without phonation impairment, the clinical result was not certain.

Adolescent↗

[In vivo tissue distribution of laryngeal cancer drained lymph node lymphocytes in tumor-bearing mice].

The distribution of 3H-TdR labeled human laryngeal cancer drained lymph node lymphocytes (LNL) to human laryngeal squamous cell carcinoma were traced in PHC3 bearing nude mice, and the radioactivity in tissues was detected. 30.7% labeled cells were localized in live in first day after transfer, and a few in lung, spleen and kidney. Labeled cells were reduced weekly and by the end of the fourth week there were still 4.3% in live, but very few were detected in the tumor site. This indicated that cancer drained LNL had no specificity to tumor, and could not infiltrate into tumor sites. So besides directly attacking tumor cells in vivo, possibly, there are some indirect mechanisms to mediate tumor regression.

Animals↗

Catecholamine-induced mechanical sensitization of cutaneous nociceptors in the rat.

C-Fiber mechanoheat (C-MH) nociceptors from the saphenous nerve were studied, in control rats and in rats that underwent surgical sympathectomy. Intradermal injection, alone, of either norepinephrine (NE) or the calcium ionophore, A23187, did not affect mechanical threshold. The combination of A23187 and NE, however, significantly decreased mechanical threshold. In the presence of the alpha 2-adrenergic antagonist, yohimbine, or the cyclooxygenase inhibitor, indomethacin, C-MHs were not sensitized by the combination of NE + A23187. One week after surgical sympathectomy, the number of C-MHs sensitized by NE + A23187 was significantly reduced. In summary, NE appears to sensitize nociceptors indirectly. These data are compatible with the suggestion that a sympathetic postganglionic neuron-dependent release of prostaglandins mediates the sensitization. NE appears to act at an alpha 2-adrenergic receptor, only in the presence of an increased intracellular Ca2+.

Action Potentials↗

Na(+)-K(+)-ATPase activity: role in the impaired sodium excretion of experimental nephrosis in rats.

Using the model of adriamycin-induced nephrotic syndrome in rats, we studied the relationship between urine electrolyte excretion rates and proteinuria and determined the activity of Na(+)-K(+)-ATPase in the renal tissue of nephrotic rats. No relationship was found between the increased sodium reabsorption and proteinuria. But the impaired salt excretion was inversely related to the increase of Na(+)-K(+)-ATPase activity in the renal inner medulla. It is proposed that direct effect of adriamycin on renal tubule cells is the primary events, that the increased Na(+)-ATPase activity on basolateral membrane of renal tubule cells be an intrarenal factor which mediates the action of retention of salt by the kidney and that inner medullary collecting ducts might be one of the sites of the sodium retention in nephrotic rats.

Albuminuria↗

Multinuclear and magic-angle spinning NMR investigations of molecular organization in phospholipid-triglyceride aqueous dispersions.

The supramolecular organization of multi-bilayers formed by aqueous egg phosphatidylcholine-triolein (PC-TO) mixtures has been investigated using 31P, 13C, and 1H nuclear magnetic resonance (NMR). For these emulsions, which mimic substrates in the early hydrolytic stages of fat digestion, the NMR spectra obtained with magic-angle spinning (MAS) exhibit resolution comparable to that of sonicated vesicles and integrated peak intensities consistent with their chemical composition. Both 31P line shapes and MAS sideband patterns from the phosphocholine group indicate that mixing with triolein produces a PC bilayer which remains predominantly liquid crystalline in its organization; nevertheless, anomalous spectral features in MAS spectra may be attributed to additional phases in which the headgroups adopt a different orientation with respect to the bilayer normal, and tight packing enhances phosphorus-phosphorus interactions. 13C and 1H line widths monitored as a function of PC mole fraction, spinning speed, and decoupling strength show that the choline headgroups and glycerol backbones are anchored preferentially in the phospholipid-triglyceride assemblies, whereas all acyl chains become very fluid. The average degree of chain order also decreases for the mixed dispersions, as judged from spinning-sideband intensities in 1H MAS NMR spectra. The absence of proton spin-diffusion effects in the PC-TO multilayers is demonstrated by examination of their spinning sidebands and relaxation times, making it possible to use MAS-assisted two-dimensional NMR to assign overlapped 1H resonances and to identify proximal interactions between the two constituents. The usefulness of these NMR strategies in mechanistic studies of gastric fat digestion is also discussed.

Carbon Isotopes↗

Regenerative neurite growth modulation associated with astrocyte proteoglycans.

Adherent GFAP-positive cells of neocortical origin in vitro produce and release members of three families of sulphated proteoglycans and a sulphated protein that copurifies with heparan sulphate proteoglycan (HSPG). Conditioned medium (CM) and the proteoglycans contained in the CM have neurite growth-promoting activity when immobilized on defined substrates of growth but not when in the nonimmobilized compartment. On a poly-D-lysine substrate, the rank ordering of specific neurite growth activity based on protein concentration was 330 kDa HSPG >> 100 kDa HSPG/chondroitin sulphate (CS) PG mixture or hybrid > 330 kDa CSPG > 50 kDa CSPG/dermatan sulphate (DS) PG mixture or hybrid and the 31 kDa sulphoprotein. Astrocyte CM lost its growth facilitatory activity when prepared and released by astrocytes in the presence of soluble mediators of inflammation. Loss of activity could not be explained by qualitative or quantitative alterations of released proteoglycans but appeared to be associated with the presence of an inhibitor. The sulphoprotein that copurified with HSPG was a potent inhibitor of HSPG-mediated neurite growth.

Animals↗

Species-specific signals for the splicing of a short Drosophila intron in vitro.

The effects of branchpoint sequence, the pyrimidine stretch, and intron size on the splicing efficiency of the Drosophila white gene second intron were examined in nuclear extracts from Drosophila and human cells. This 74-nucleotide intron is typical of many Drosophila introns in that it lacks a significant pyrimidine stretch and is below the minimum size required for splicing in human nuclear extracts. Alteration of sequences of adjacent to the 3' splice site to create a pyrimidine stretch was necessary for splicing in human, but not Drosophila, extracts. Increasing the size of this intron with insertions between the 5' splice site and the branchpoint greatly reduced the efficiency of splicing of introns longer than 79 nucleotides in Drosophila extracts but had an opposite effect in human extracts, in which introns longer than 78 nucleotides were spliced with much greater efficiency. The white-apricot copia insertion is immediately adjacent to the branchpoint normally used in the splicing of this intron, and a copia long terminal repeat insertion prevents splicing in Drosophila, but not human, extracts. However, a consensus branchpoint does not restore the splicing of introns containing the copia long terminal repeat, and alteration of the wild-type branchpoint sequence alone does not eliminate splicing. These results demonstrate species specificity of splicing signals, particularly pyrimidine stretch and size requirements, and raise the possibility that variant mechanisms not found in mammals may operate in the splicing of small introns in Drosophila and possibly other species.

Animals↗

Candida zeylanoides causing candidiasis as tinea cruris.

Candida zeylanoides caused candidiasis as tinea cruris in 4 cases. Candida zeylanoides were characterized by good growth of the strain in malt medium, potato dextrose agar and Sabourard's agar. Their colony was milky white and greasy with smooth surface. The diameter of the colony reaches 12 mm within a week. As candida type pseudohyphae but not hyphae, they do not produce ascospore and bolospore. Carbon sources fermentation showed positive results. Nitrogen sources assimilation agar (KNO3) negative, arbutin agar negative, nonvitamin medium positive. G+C mol% value of their DNA was 51.24. Animal experiment showed that guinea pigs were infected by Candida zeylanoides. The main feature of candidiasis as tinea cruris caused by the strain was pink infiltrative erythema with clear margin, a lot of grain-sized papules, a few vesicles, and thin scales. The disease can be cured by preparation of ketoconazole.

Adult↗

Suppression of autoimmune disease by dietary n-3 fatty acids.

Previous studies have demonstrated that dietary fish oil preparations have anti-inflammatory effects in humans and in experimental animals, but the individual components of fish oils that are responsible for their anti-inflammatory effects have not been documented. We therefore investigated in (NZB x NZW)F1 mice, a model for human systemic lupus erythematosus, the effects of diets containing ethyl esters of two purified n-3 fatty acids, eicosapentaenoic acid (EPA-E) and docosahexaenoic acid (DHA-E), a refined fish oil triglyceride (FO) which contained 55% n-3 fatty acids, and beef tallow (BT) which contains no n-3 fatty acids. The diets were initiated prior to the development of overt renal disease at age 22 weeks, and continued for 14 weeks. The extent of the renal disease was quantified by light microscopy and by proteinuria. Diets containing either 10 wt% FO, 10% EPA-E, or 6% or 10% DHA-E alleviated the severity of the renal disease, compared to the BT diet, whereas diets containing either 3% or 6% EPA-E or 3% DHA-E were less effective. Two diets containing approximately 3:1 mixtures of EPA-E and DHA-E alleviated the renal disease to a greater extent than expected for either of these fatty acids given singly. We believe that these experiments provide the first demonstration of anti-inflammatory effects of individual dietary n-3 fatty acids. The results also indicate that the anti-inflammatory effects of fish oils depend on synergistic effects of at least two n-3 fatty acids.

Animals↗

A basic study on the hybridoma cell culture of microencapsulation.

We report here that the constitute component of Na alginate is a very important factor on microcapsular strength. We developed a method of estimating viable cell count in batch microcapsular process and the factors influencing the full loading rate in microcapsules. The physical integrity of microcapsule and full loading rate were greater than 95%. The cell line of C3 hybridoma was found to reach maximum intracapsule cell density of 8.8 x 10(6) - -2.1 x 10(7) cells/ml during static culture period of 6-10 days. During this period, the mouse monoclonal antibody accumulated in the intracapsular space to a final concentration of 379 micrograms/ml. Analysis of intracapsular protein by SDS gel electrophoresis during the culture period demonstrated that there was one band or two bands of protein which means its purity is relatively high.

Alginates↗

[Effects of mixture of Astragalus membranaceus, Fructus Ligustri lucidi and Eclipta prostrata on immune function in mice].

A Chinese medicine mixture containing Astragalus membranaceus, Fructus Ligustri Lucidi and Eclipta prostrata(AFE), was fed to mice 9g/kg, 20g/kg, respectively for seven days. Observe the effects of AFE on the immune function in mice. The experiment showed that the two dosages of AFE could obviously raise the conversion percentage of lymphocytes (P < 0.01) and serum IgG level (41%-47%) of the mice. The weights of the thymus and spleensed increased in the two groups compared with those in the normal control. The larger dosage of AFE could also raise activity of Adenosine Deaminase (ADA) obviously (P < 0.01). AFE turned out a resistance to the immunosuppressive effect caused by cyclophosphamide.

Adenosine Deaminase↗

[Facilitatory effect of Pinellia ternata lectin on quantal release of acetylcholine from nerve terminals].

Pinellia ternata lectin (PTL) extracted from the rhizome of Pinellia ternata Briet by porcine thyroglobulin-Sepharose 4B column exhibits hemagglutination activity and carbohydrate binding specificity for mannan. Here we reported the effects of PTL on the resting membrane potential of muscle fiber and on the release of acetylcholine (ACh) from the motor nerve terminals in the phrenic nerve diaphragm preparations of mice. The results showed that PTL increased the frequency of miniature end-plate potential (MEPP). In 30 min after the treatment of the preparation with lectin 100 micrograms.ml-1, the frequency of MEPP reached 20 times higher than that of the control. Addition of mannan 1 mg.ml-1 restored the raised discharge of MEPP to its control level immediately. Similar to the effect of PTL on MEPP frequency, the amplitude and mean quantal content of end-plate potential also increased after PTL. At 100 micrograms.ml-1, the lectin depolarized the muscle membrane slightly, while at 10 micrograms.ml-1 no effect on the membrane potential was found. These results were interpreted as the intracellular Ca2+ elevation due to a permeability increase of the nerve terminal to ions after PTL.

Acetylcholine↗