Biomedical subjects
Publications and source records attributed to M Sha.
A HPLC method for the determination of chrysophanol in Semen Cassiae was investigated. The result showed that this method was simple, specific and accurate. The recovery was 99.0% and relative standard deviation was 1.8%. The method is useful for the quality control of this medicinal meaterial.
The contents of myristicin and safrol in the volatile oil of nutmeg and its processed products were determined by HPLC. This method is fast, accurate and gives good resolution. It has also been confirmed that myristicin tends to decrease in varying degrees after the nutmeg has been processed.
A HPLC method for the determination of eugenol, methyleugenol and methylisoeugenol in the volatile oil of differently processed natmeg has been used. The result has shown that the content of eugenol is only sliahtly changed before and after processing, but that of methyleugenol and methylisoeugenol has obviously increased.
An HPLC method for determination of icariin in epimedium koreanum nakai was investigated. The results showed that this method was simple, specific and accurate. The recovery was 97.6% and relative standard deviation was 1.2%. About 0.5 g of dried powdered crude drug was weighed accurately, placed in 25 mL of the mobile phase and refluxed on a water-bath for 30 min. After cooling, the solution was decanted. The residue was refluxed twice with 10 mL of the mobile phase. The extract were placed in a 50 mL volumetric flask and diluted to 50 mL with the mobile phase. A 3 microL of the solution was injected into the HPLC system. Linear calibration graphs for icariin were obtained for the concentration ranges of 0.08-0.4 microg. HPLC conditions were used was Shimadzu LC-6A with UV spectrometric detector SPD-6AV; at 270 nm and auto injector SIL-6A. Water-acetonitrile (70:30) as the mobile phase, Shim-pack CLC-ODS column (6.0 mm x 150 mm).
The structural features of wheat germ protein synthesis initiation factor eIF-(iso)4F, which has a cap binding protein as one of its two subunits, are unknown. In this study, circular dichroism (CD) spectra and secondary structure prediction were obtained for eIF-(iso)4F and its two subunits, p28 and p86. The alpha-helix content of eIF-(iso)4F changed from 42% at pH 6.3 to 15% at pH 7.6, the optimum pH for cap binding. The beta-sheet content increased from 14% (pH 6.3) to 38% at pH 7.6. The CD spectra of the two subunits, p28 and p86 were also measured and analyzed. The separated subunits both had a higher alpha-helix content at pH 7.6 than the native protein, giving values of 60% and 34% alpha-helix for p28 and p86, respectively. Binding of the dinucleotide cap analog to p28 reduced the alpha-helix content to approximately 8% with an increase in the beta sheet content from 10% to 37%. The conformational changes in eIF-(iso)4F upon binding with mRNA are dependent on cap or oligonucleotide structure. A conformation consisting of approximately the same alpha-helix and beta-sheet content can be induced by ligands even at non-optimal pH values. This large conformational transition suggests eIF-(iso)4F binds nucleic acids by interaction of a beta-sheet motif and that this conformational transition may have a regulatory role.
The quantitative changes of flavonoids in Epimedium koreanum in different collecting periods were determined by HPLC and UV spectrophotometry. The result shows that the highest content of flavonoids is found in the flowering period (May).
The chlorogenic acid content in Epimedium koreanum was determined by HPLC. The result shows that this method is simple, specific and accurate. The recovery was 97.5% and relative standard deviation was 1.4%. With good reproducibility and wide response linearity, the method can be used for the quality control of this herbal medicine.
The content of magnoflorine in different parts of Epimedium koreanum was determined by using HPLC. The results showed that magnoflorine existed in every part of the plant and the highest content was found in the rhizoma. A new index and a reliable method are correspondingly provided for the quality control of E. koreanum.
The binding of p28, p86, and native wheat germ eIF-(iso)4F with m7GTP and oligonucleotides was measured and compared. The purified subunits (p28, 28 kDa and p86, 86 kDa) of wheat germ protein synthesis initiation factor eIF-(iso)4F have been obtained from Escherichia coli expression of the cloned DNA (van Heerden, A., and Browning, K. S. (1994) J. Biol. Chem. 269, 17454-17457). The binding of the 5'-terminal cap analogue m7GTP to the small subunit (p28) of eIF-(iso)4F as a function of pH, temperature, and ionic strength is described. The mode of binding of p28 to cap analogues is very similar to the intact protein. Assuming that all tryptophan residues contribute to p28 and eIF-(iso)4F fluorescence, iodide quenching shows that all 9 tryptophan residues in p28 are solvent-accessible, while only 6 out of 16 tryptophan residues are solvent-accessible on the intact eIF-(iso)4F. The fluorescence stopped-flow studies of eIF-(iso)4F and p28 with cap show a concentration-independent conformational change. The rate of this conformational change was approximately 10-fold faster for the isolated p28 compared with the native eIF-(iso)4F. From these studies it appears that cap recognition resides in the p28 subunit. However, p86 enhances the interaction with capped oligonucleotides and probably is involved in protein-protein interactions as well. Both subunits are required for helicase activity.
Upstream stimulatory factor USF is a human transcriptional activation factor, which uses a basic/helix-loop-helix/ leucin zipper (b/HLH/Z) motif to homodimerize and recognize specific sequences in the promoter region of both nuclear and viral genes transcribed by RNA polymerase II. Steady state fluorescence spectroscopy demonstrated that the basic/helix-loop-helix/leucin zipper domain of USF binds its DNA targets with high affinity and specificity, whereas removal of the leucine zipper yielding the basic/helix-loop-helix minimal DNA binding region reduces both affinity and specificity. Stopped flow method provided kinetic evidence for a two-step binding process involving rapid formation of a protein-DNA intermediate followed by a slow isomerization step, which is consistent with the basic region undergoing a random coil to alpha-helix folding transition on specific DNA recognition. The leucine zipper is also necessary for USF to function as a bivalent homotetramer, capable of binding two distinct recognition sites simultaneously and mediating DNA looping under physiologic conditions. Titration studies revealed that the first binding event has a equilibrium constant Keq = (2.2 +/- 2.0) x 10(9) M-1 for major late promoter DNA, whereas the second binding event occurs with a remarkable reduced affinity, Keq = (1.2 +/- 0.8) x 10(8) M-1. This anticooperative feature of DNA binding by the homotetramer suggests that USF stimulates transcription by mediating DNA looping between nearby recognition sites located in class II nuclear and viral gene promoters.
The zinc finger gene MZF-1 is preferentially expressed in primitive hematopoietic cells and plays an important role in regulating myelopoiesis. Regulators of development are potential targets for neoplastic transformation. This study investigated whether unregulated expression of MZF-1 could function as an oncogene. Retroviral transduction and subsequent overexpression of MZF-1 resulted in loss of contact inhibition, loss of substrate dependence, and more rapid cell cycling in NIH 3T3 cells. The MZF-1-transformed 3T3 cells formed aggressive tumors in athymic mice. Disruption of the tight lineage- and stage-specific regulation of MZF-1 can result in neoplastic transformation of embryonic fibroblasts. Therefore, MZF-1 represents a novel oncogene.
The respiratory management strategy of small tidal volume with permissive hypercapnia has been adopted to avoid further aggravation of lung injury due to high airway pressure with some impressive success (1). No consensus, however, has been established in terms of the rate of increase in PaCO2 and its upper limit. Recently, our colleague in the intensive care unit experienced a severe case of ARDS successfully treated with the above strategy despite of the fact that during the course of treatment, the highest PaCO2 reached 177 mmHg and the lowest pH, 7.03 (2). The fact that PaCO2 may reach a very high level in the clinical setting and the well-known role of haemoglobin (Hb) in buffering CO2 led us to study effects of different Hb levels on pH and haemodynamic changes in response to acute CO2 loading in the blood. We will summarize the case report first with permission of authors (the case report was published in Japanese) (2) and then discuss the studies conducted in our animal laboratory.
A HPLC method for the determination of hyperin in Epimedium koreanum was investigated. The result shows that this method is simple, specific and accurate. The recovery was 97.4% and relative standard deviation was 1.2%. With good reproducibility and wide response linearity, the method can be used for the quality control of this herbal medicine.
We report a case of postoperative sudden death during Holter-ECG examination in a 62-yr-old male, who experienced intraoperative cardiac arrest possibly due to myocardial ischemia. Although the patient recovered from intraoperative event without any neurological sequelae, he suffered from spontaneous ventricular tachycardia following mild ST segment depression that led to cardiac arrest on the 58th postoperative day. Precise mechanism of sudden death was not clear because coronary angiography or autopsy was not performed. However, the postoperative Holter-ECG revealed frequent episodes of silent 0.5-1.0 mm ST segment depression during tachycardia which had not been observed in the preoperative 12-lead ECG. Thus a likely explanation would be that the patient had the undetected coronary artery disease with frequent episodes of silent ischemia and finally was led to the fatal arrhythmia. In this case, so called "stunned myocardium" following repeated silent ischemia may have also contributed to the life-threatening arrhythmias. This case suggests that even mild ST depression might lead to life-threatening arrhythmias in the patients with silent ischemia. Adequate preoperative evaluation and careful perioperative observation are necessary for these patients.
We report a case of substantial rebreathing which occurred during the thoracoscopic bulla resection despite a normal FICO2 reading on capnogram. Early detection of inspiratory unidirectional valve malfunction as the cause of the rebreathing was only possible by careful observation of the capnogram pattern. During the course of one lung anesthesia, a rising end-tidal CO2 concentration (FETCO2) and a change in the pattern of the capnogram were observed. However, the lowest FICO2 value in the late phase of inspiration stayed below the alarm limit setting of rebreathing. For this reason, the capnograph failed to identify the beginning of inspiration and perceived the high FICO2 value in early inspiration as part of expiratory plateau. In case of the inspiratory valve malfunction, it is possible that analysis of the capnogram reveals underestimated FICO2.
The binding of oligoribonucleotides to wheat germ protein synthesis initiation factor eIF-4B was measured by direct fluorescence techniques. An analysis of the equilibrium association constants (Keq) indicates that eIF-4B binding is not affected by the m7GTP cap structure or the AUG. eIF-4B is insensitive to hairpin structures within the oligoribonucleotide. The binding site size is approximately 18 bases. The binding of oligoribonucleotide to eIF-4B as a function of pH, temperature, and ionic strength is also described. The pH-dependent binding showed an increase in binding with increasing pH in contrast to the sharp pH optimum observed for cap binding protein eIF-4E (Carberry, S. E., Darzynkiewicz, E., and Goss, D.J. (1991) Biochemistry 30, 1624-1627). Assuming all tryptophan residues contribute to the observed fluorescence, iodide quenching showed that 8(+/- 1) out 9 of eIF-4B's tryptophan residues are on the surface of the eIF-4B protein. A specific anion effect of Cl- on eIF-4B binding to oligoribonucleotide was found when comparing the ionic strength effect of KC2H3O2 and KCl.
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