Biomedical subjects
Publications and source records attributed to K Zhang.
Nine patients with hyperprolactinemia and one patient with pituitary microadenona were observed for 6 years. They were induced by administration of domperidone. The clinical characteristic of the 9 patients was summarized and analysed. The results suggest that prescribe domperidone for fertile women should pay more attention to its adverse effect on inducing hyperprolactinemia and even pituitary microadenona.
The frontal sinus of 47 adult half-head cadaveric specimens were observed. The case of the sinus opening into nasal cavity directly through the ostia are 30 to frontal recess, 9 to ethmoidal infundibulum, 3 to superior semilunar hiatus and superior meatus, respectively. Only 4 (8.5%) cases are directly opened into the nasofrontal duct. The adjacent structures of the ostia differ from each other by the different location of the ostium. The clinical significance of the ostium and the nasofrontal duct were discussed.
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OBJECTIVE: To improve the diagnosis and treatment of pulmonary carcinosarcoma. METHOD: Two patients with pulmonary carcinosarcoma were confirmed by operation and pathology were presented and relevant literatures were reviewed. The histo-pathological, clinical features, diagnosis, differential diagnosis and treatment were introduced appearance. RESULT: Carcinosarcoma of the lung is rare. It is 0.2%-0.6% of pulmonary malignant tumor. Carcinosarcoma of the lung may be divided into 2 types: First, the endbronchial type which tends to grow slowly in a polypoid pattern along the major bronchi with local invasive feature. The second, arising peripherally which tends to metastasize early with serious outcome. CONCLUSION: This tumor may be misdiagnosed as brondrogeuic carciniose preoperatively. It tends to metastasize early and prognosis is poor. Surgical intervention is the first choice.
OBJECTIVE: To study the surgical approach for cranial base tumors removal. METHODS: Ten cases of cranial base tumors were thoroughly resected via pre-auriculal temporo-sphenoidal approach. Among them, 9 cases with defects of cranial base or nasopharynx were reconstructed with the temporal muscle and fascia in the same operative field. RESULTS: Patients were followed up from 21 months to 7 years. In 2 cases with recurrent cranial base tumors 1 died of recurrence, 1 lived with the tumor. Eight cases achieved good clinical results without severe complications except 1, who got necrosis of temporal muscle. CONCLUSION: The preauricular temporo-sphenoidal approach not only provides an excellent exposure to the compartments of the skull base with a limited injury to the normal tissues, but also offers a convenient way in reconstructing defects with temporal muscle in the same operative field. The incision scar is hidden and the eosmetic affect small. It has been shown that the approach can offer some advantages in surgical treatment of cranial base tumors selectively.
OBJECTIVE: To study the effect of ischemia-reperfusion on membrane structure and function in rat retina. METHODS: Thirty-two SD rats were randomly grouped into 4 groups. Group 1 served as the control group, group 2, 3 and 4 served as reperfusion 3 hours, 30 hours and 5 days respectively. The intraocular pressure (IOP) was raised to occlude retinal and choroidal blood vessels to form retinal ischemia; afterwards the IOP was lowered to normal to allow reperfusion. The animal was sacrificed after reperfusion. The colorimetric determination of phosphorus was used to investigate Na(+)-K(+)-ATPase activity of rat retina; the cellular membrane was labelled by fluorescence probe DPH to detect its fluidity which was measured by means of fluorescence spectrophotometer. RESULTS: Na(+)-K(+)-ATPase and membrane influidity were damaged at early stage. The longer the ischemia, the more serious was the reperfusion injury. CONCLUSIONS: The mechanism of the decrease of Na(+)-K(+)-ATPase activity is due to the production of substances involved in peroxidation and excitatory amino acid (EAA) which are produced during reperfusion. They can damage the Na(+)-K(+)-ATPase directly. Lipid peroxidation disrupts membrane integrity and causes decrease of membrane influidity. For these reasons, membrane stability is reduced and Na(+)-K(+)-ATPase protein function is changed.
OBJECTIVE: To compare the accuracy of corneal topography, keratometer and cycloplegic retinoscopy in measuring astigmatism for refractive surgery. METHODS: Three hundred and sixty eyes with ametropia were randomly selected. The results of corneal topography, that of keratometer and cycloplegic retinoscopy in measuring astigmatism before refractive surgery were compared, and the measuring results of corneal topography and that of keratometer for 72 eyes after photorefractive keratectomy (PRK) and 95 eyes after laser in situ keratomileusis (LASIK) were also compared. RESULTS: No significant difference was found in axes of astigmatism among the three groups. As for diopters of astigmatism, there was no significant difference between the group of corneal topography (DeltaSim K) and the group of keratometer (DeltaK), but we found significant difference between the group of cycloplegic retinoscopy and the other two groups before and after refractive surgery. Significant difference was also found between DeltaSimK and DeltaK after PRK and LASIK. CONCLUSIONS: Our investigation demonstrates that before refractive surgery the keratometer has a similar clinical value as that of corneal topography, and the DeltaSim K value is related to the graphic pattern of corneal topography. However, keratometer is limited in measuring mild changes in corneal curvature after refractive surgery, while the astigmatism expressed by DeltaSim K in corneal topography is more accurate.
OBJECTIVE: To further explore the cause, mechanism and surgical treatment of idiopathic hemifacial spasm (IHFS). METHODS: Routine sagittal and coronal cryoslices of 8 (16 sides) pons were made. The sections were stained with Luxol fast blue and Nissl stains. The location of the facial nucleus and pathway of facial neurofibers in the pons were observed. Twenty-five patients with IHFS whose facial nerve root exit zone(REZ) was not compressed by vessels underwent microvascular decompression of pons. RESULTS: The distances from the facial nucleus to the ventral surface of pons, the median line, and the ventroexterior surface were 12.0-12.5 mm, 6.0 mm, and 7.5-9.0 mm respectively. The distance from the facial neurofibers in the pons to the surface of the pons was 1.0 to 2.0 mm, with an average of 1.65 mm. The vascular compression was at the surface of pons, within 4 mm anterosuperior to the REZ in 25 IHFS patients. The compressing vessels were the anterior inferior cerebellar arteries and their branches. The results of decompression in 25 patients with IHFS were as follows: spasm immediately disappeared in 8 patients, and within one week in 17 patients. No recurrence was found during a follow-up period from 6 months to 5 years. CONCLUSION: The main cause of IHFS was vascular compression, but the position of compression is not necessarily always at the REZ. The "short-circuiting" theory can only explain the cases with vascular compression at the REZ. But in cases who do not have vascular compression at the REZ, there might be dysfunction of the facial nucleus. In the present cases, vascular compression was at the surface of the brain stem anterosuperior to the REZ, pons microvascular decompression is an effective treatment.
OBJECTIVES: To study the role of nutritional factor in the development of postoperative complications in patients with head and neck malignancies. METHODS: Postoperative complications of 96 patients with head and neck malignancies who were operated on were surveyed. Twenty-seven developed postoperative complications; the remaining 69 went uneventful. Comparisons of nutritional status and clinical variables between these two groups were made. RESULTS: 1. The prevalence of poor preoperative nutritional status in the complication group (56%) was higher as compared with that in the noncomplication group (20%) (P < 0.001); 2. values of body weight, triceps skin fold thickness, arm circumference, arm muscle circumference, and creatinine-height index in the complication group decreased much more significantly than in the noncomplication group (P < 0.001); 3. the nitrogen and calorie intake within the first postoperative week was lower in the complication group than in the non-complication group (P < 0.001). CONCLUSIONS: Nutritional factor plays a very important role in the development of postoperative complication and the perioperative nutritional support for head and neck surgical patients should not be ignored.
A lipase-producing bacterium strain was isolated from soil and was identified as Pseudomonas sp.. Its lipase yield was improved 2.25-fold by combined treatment of UV irradiation and NTG. The lipase fermentation condition for the mutant strain was optimized with Plackett-Burman design and Response Surface Analysis (RSA), and the formula of the optimum medium suitable for industrial scale fermentation was thereby established. A maximum yield of 87.5 U/ml was obtained.
In this paper, pharmacognostiacal identification of Humulus scandens was studied. The character of medicinal materials, histological and powder characteristics for the setem and leaf of H. scandens were mainly reported. The microscopical features for leaf is typical identified basis.
PURPOSE: To identify gene arrangement, chromosomal localization, and expression pattern of mouse guanylate cyclase activating proteins GCAP1 and GCAP2, retina-specific Ca2+-binding proteins, and photoreceptor guanylate cyclase activators. METHODS: The GCAP1 and GCAP2 genes were cloned from genomic libraries and sequenced. The chromosomal localization of the GCAP array was determined using fluorescent in situ hybridization. The expression of GCAP1 and GCAP2 in mouse retinal tissue was determined by immunocytochemistry. RESULTS: In this study, the mouse GCAP1 and GCAP2 gene array, its chromosomal localization, RNA transcripts, and immunolocalization of the gene products were fully characterized. The GCAP tail-to-tail array is located at the D band of chromosome 17. Each gene is transcribed into a single transcript of 0.8 kb (GCAP1) and 2 kb (GCAP2). Immunocytochemistry showed that both GCAP genes are expressed in retinal photoreceptor cells, but GCAP2 was nearly undetectable in cones. GCAP2 was also found in amacrine and ganglion cells of the inner retina. Light-adapted and dark-adapted retinas showed no significant difference in the distribution of the most intense GCAP2 staining within the outer segment and outer plexiform layers. CONCLUSIONS: Identical GCAP gene structures and the existence of the tail-to-tail gene array in mouse and human suggest an ancient gene duplication-inversion event preceding mammalian diversification. Identification of both GCAPs in synaptic regions, and of GCAP2 in the inner retina suggest roles of these Ca-binding proteins in addition to regulation of phototransduction.
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The double helix is a ubiquitous feature of RNA molecules and provides a target for nucleases involved in RNA maturation and decay. Escherichia coli ribonuclease III participates in maturation and decay pathways by site-specifically cleaving double-helical structures in cellular and viral RNAs. The site of cleavage can determine RNA functional activity and half-life and is specified in part by local tertiary structure elements such as internal loops. The involvement of base pair sequence in determining cleavage sites is unclear, because RNase III can efficiently degrade polymeric double-stranded RNAs of low sequence complexity. An alignment of RNase III substrates revealed an exclusion of specific Watson-Crick bp sequences at defined positions relative to the cleavage site. Inclusion of these "disfavored" sequences in a model substrate strongly inhibited cleavage in vitro by interfering with RNase III binding. Substrate cleavage also was inhibited by a 3-bp sequence from the selenocysteine-accepting tRNASec, which acts as an antideterminant of EF-Tu binding to tRNASec. The inhibitory bp sequences, together with local tertiary structure, can confer site specificity to cleavage of cellular and viral substrates without constraining the degradative action of RNase III on polymeric double-stranded RNA. Base pair antideterminants also may protect double-helical elements in other RNA molecules with essential functions.
The effects of forty-one plant polyphenols on the activity of glutathione reductase (GSH-RD) were studied. These polyphenols showed varying degrees of concentration-dependent inhibition on the enzyme, with IC50 values that varied from approximately 40 microM to 1 mM. 4'-Hydroxychalcone and tannic acid were among the more potent inhibitors, with IC50 values of 47.3 and 50.4 microM, respectively. Different classes of polyphenols varied in potency in the following order: chalcones > tannic acid > flavonoids > coumarins > catechins. Analysis of structure-activity relationships showed certain chemical structures to be important for the inhibition of GSH-RD: (a) C-5 and C-7 hydroxylations in the A-ring, a carbonyl group at C-4, and the B-ring attached to C-2 in flavonoids; (b) C-2' and C-4' hydroxylations in chalcones; and (c) C-6 and C-7 hydroxylations in coumarins. The inhibition of GSH-RD by tannic acid and quercetin was time dependent and irreversible, whereas that by 4'-hydroxychalcone and esculin was reversible but not time dependent. Enhanced inhibition of GSH-RD by the four polyphenols 4'-hydroxychalcone, quercetin, butein, and acacetin was observed in the presence of NADPH. Kinetic studies showed that both tannic acid and 4'-hydroxychalcone exhibited non-competitive inhibition on GSH-RD towards glutathione disulfide.
In this study, norcantharidin was compared with adriamycin and mitomycin C for its inhibitory action in the growth of cultured human hepatocellular carcinoma HepG2 cells. The IC50 of adriamycin and mitomycin C on HepG2 cells was 7.3 microM and 27 microM, respectively, whereas the IC50 of norcantharidin for inhibiting the growth of HepG2 cells was as high as 1900 microM. After HepG2 tumor-bearing nude mice were treated with 12 daily intraperitoneal injections of norcantharidin (2 mg/kg), the increase in tumor size was significantly slower than that of untreated controls. The mean survival time of untreated tumor-bearing nude mice was 129 days, whereas in the tumor-bearing nude mice treated with norcantharidin, the mean survival time was significantly prolonged to 194 days (P < 0.0001). It is concluded that norcantharidin may have a potential role in the treatment of human hepatocellular carcinoma.
Chlorambucil (CMB), an anticancer drug, was cytotoxic at concentrations of 5-20 microM to human colon adenocarcinoma cells. It inhibited [14C]thymidine uptake in a dose-dependent manner. Both effects were potentiated by simultaneous exposure of the cells to 10 microM plant polyphenols. In an attempt to explain the possible mechanism of action of the polyphenols in relation to these observations, an HPLC-radiometric method was developed to measure the conjugation of CMB with glutathione in these cells and to monitor the export of monochloromonoglutathionyl CMB (MG-CMB), its main glutathione conjugate. At micromolar concentrations, five polyphenols, namely quercetin, butein, tannic acid, 2'-hydroxychalcone and morin, inhibited the efflux of CMB significantly; an inhibition of 40% was observed with 10 microM quercetin. The glutathione S-transferase (GST) activity of the cancer cells, measured with 1-chloro-2,4-dinitrobenzene, was also inhibited by the polyphenols. Their combined action on GST and on the efflux of MG-CMB conjugate could provide an enhanced positive modulation of sensitivity of the tumour cells to CMB.
We readily produced recombinant pro-macrophage stimulating protein in a mammalian expression system, but it was only weakly active after proteolytic activation. Active macrophage stimulating protein is a disulfide-bonded heterodimer, but in our hands, the subunits of recombinant macrophage stimulating protein were mostly not disulfide bonded. Molecular modeling of the serine proteinase domain of macrophage stimulating protein based on homology to human trypsin suggested that macrophage stimulating protein, but not plasminogen or hepatocyte growth factor, has a Cys residue (672) in close proximity to the Cys residue (578) that forms the intersubunit disulfide link with the other subunit. We hypothesized that Cys672 might interfere with intersubunit disulfide formation by forming an intrasubunit disulfide with Cys578 and therefore mutated Cys672 to Ala. After kallikrein activation, the subunits of Cys672 --> Ala macrophage stimulating protein were fully disulfide linked, and the mutant macrophage stimulating protein had 10-20-fold higher specific activity than the wild type recombinant macrophage stimulating protein.