Search PubMed⌕ Search

Biomedical subjects

M Z Zhang

Publications and source records attributed to M Z Zhang.

32 records · Page 2Linked to original sources
PubMed1995

A new strategy for enhancing the stability of lyophilized protein: the effect of the reconstitution medium on keratinocyte growth factor.

PURPOSE: Protein stabilization during lyophilization has previously focused on optimization of the formulation as well as the freezing and dehydration process parameters. However, the effect of the reconstitution medium has been largely neglected. We have investigated its effect on aggregate formation using recombinant keratinocyte growth factor (KGF). METHODS: The protein was lyophilized under suboptimal conditions to induce aggregation and precipitation upon reconstitution with water. A series of additives were examined by UV spectrophotometry and size exclusion chromatography (SEC-HPLC) for their effects on decreasing the degree of KGF aggregation and precipitation by the increase in recovery of soluble monomer. RESULTS: Several additives resulted in a significant reduction of aggregation, including sulfated polysaccharides, surfactants, polyphosphates, and amino acids. A similar effect was achieved by adjusting the ionic strength of the reconstitution medium. SEC-HPLC indicated that the amount of soluble monomer was also increased by these additives suggesting that the recovery of the soluble protein correlates with the native, monomeric protein. CONCLUSIONS: These results suggest that optimization of reconstitution conditions will be a useful methodology for increasing the recovery of soluble, active proteins and that for KGF, the recovery of the soluble protein correlates with the native, monomeric form.

Animals↗
PubMed1994

[Diagnosis and treatment of hydronephrosis: report of 100 cases].

One hundred patients with hydronephrosis were treated for 10 years. In 88 patients operations confirmed the causes of obstruction including pyelo-ureteral junction obstruction (pujo, 46 cases), anomalous (15), retroperitoneal fibrosis (15), ureteral polyps and valves and others (12). In accordance with etiology and renal function pyeloplasty was carried out in 31 cases, nephrectomy 37 and nephrostomy 12; other operation was done in 20 cases. The successful rate of pyeloplasty was 91.3%. Early diagnosis and treatment of hydronephrosis is key for reserving renal function. Renal r-scan, percutaneous nephrostomy are useful in judging renal function. Dual-Flex stent internal drainage is better than external drainage when pyeloplasty is done.

Adolescent↗
PubMed1993

[Studies on the phospho-tyrosine proteins during the proliferation cycle of cultured aortic smooth muscle cells].

The dynamic change and distribution of phospho-tyrosine proteins (P-tyr-Pr) during the cell cycle of cultured rabbit aortic smooth muscle cells (ASMC) were studied by ELISA and immunohistochemical technique. The antibody which was specific for P-tyr-Pr was prepared by immunizing California white rabbits with synthesized phospho-tyrosine bovine serum albumin, and then the IgG obtained was purified and coupled to horseradish peroxidase to make it ready for use in ELISA. We find that the content of particle P-tyr-Pr fluctuated in G1 stage, both in the cytosol and in the nucleus, being the highest at late G1 stage (9 h after G0), and the content of particle P-tyr-Pr was much higher in the nucleus than in the cytosol throughout G1 stage. The immunohistochemical study, which locates the distribution of P-tyr-Pr in ASMC, also revealed that the nuclei were stained much darker than the cytosol, and the total P-tyr-Pr content (including both particle and soluble P-tyr-Pr) was the highest at late G1 stage, or higher than at G0 and before S stage (12 h after G0). But the distribution before S stage was similar to that at late G1 stage, and although the total content before S stage was lower than at late G1 stage, it was evidently higher than that at G0 stage. This last finding might have some bearing on the role of tyrosine protein kinase in the events of a cell cycle.

Animals↗
PubMed1993

[Effects of atropine on contraction of rabbit aortic smooth muscle and cell proliferation].

The calcium antagonistic actions of atropine (Atr) and verapamil (Ver) were studied on the contraction of rabbit thoracic aorta strips induced by CaCl2 and KCl. Both Atr and Ver were found to depress the contraction as demonstrated by the shift-to-right of the dose-effect relationship curves and the decrease of maximal responses, with the value of pD'2 being 4.4 and 5.8 respectively. The intracellular Ca(2+)-dependent component of NE-induced aortic strip contraction was also inhibited by the 2 drugs, but the extracellular Ca(2+)-dependent component was barely or not inhibited by Atr before its concentration was raised to 100 mumol/L. These results indicate that the depressive effect of Atr on aortic contraction is mainly exerted by acting on the PDC (potential-dependent channel). The action of Atr on proliferation of cells was also studied in rabbit aortic smooth muscle cell (ASMC) culture. The growth was inhibited by Atr when Ca2+ was present in the medium. When Ca2+ was absent, however, the growth was stimulated by Atr 20.6-185.2 mumol/L, but inhibited by Atr 555.7-1666.7 mumol/L, suggesting that Ca2+ is somehow involved in the action of Atr on ASMC growth.

Animals↗
PubMed1992

[Calcium antagonism of anisodamine on isolated rabbit thoracic aorta].

Anisodamine (Ani) or verapamil (Ver) relaxed the contracted thoracic aortic strips induced by CaCl2 and KCl in a noncompetitive manner with pD2' 3.6 and 5.8, respectively. Ani 50 mumol.L-1 and Ver 1 mumol.L-1 inhibited the intracellular Ca(2+)-dependent component of norepinephrine-induced contraction of aorta, but Ani 0.1 mmol.L-1 did not decrease the extracellular Ca(2+)-dependent component. In the presence of Ca2+, Ani 2.3 mumol.L-1 inhibited the proliferation of aortic smooth muscle cells. In the absence of Ca2+, the effect induced by Ani was biphasic-stimulatory at 2.3 mumol.L-1 concentrations and inhibitory at 61.7 mumol.L-1 concentrations. These results suggest that Ani, similar to Ver, mainly inhibits the potentially operated calcium channels.

Animals↗
PubMed1992

[The dynamics of two types of tyrosine protein kinases in the proliferation of cultivated vascular smooth muscle cells].

We have studied the membrane-bound tyrosine protein kinases (TPK) in cultivated aortic smooth muscle cells (ASMC) from the rabbit, and found that the cytosolic (membranous)TPK and the nuclear (membranous)TPK are two distinctive types of isozymes as judged by criteria on dynamics: (1) using synthetic poly(Glu. Ala. Tyr)n(6:3:1) as a substrate, the relative extents of stimulation by Mn2+ (450%) was more effective than that by Mg2+ (100%) on cytosolic TPK, but Mn2+ was less effective (100%) than Mg2+ (130%) on nuclear TPK: (2) the concentrations of Mn2+ and Mg2+ giving maximal stimulation on cytosolic TPK were 15 mmol/L and 50 mmol/L, whereas on nuclear TPK were 1 mmol/L and 5 mmol/L, respectively. These results indicate that the attitudes toward Mn2+ and Mg2+ can distinguish the cytosolic TPK from the nuclear one. In nucleus, with the entry of ASMC from G0 to G1 stage, TPK activity increased rapidly and reached the peak (12 times G0 activity) at the early G1 stage (3 hrs from G0), then decreased dramatically to basic line, and remained at a lower level thereafter. In cytosol, the TPK activity decreased with the entry of ASMC from G0 to G1 stage and reached its lowest point at the middle of G1 stage (6 hrs from G0), and then increased with a transient peak at the late G1 stage (9 hrs). It went down to G0 level before DNA synthesis.

Animals↗
PubMed1991

[Indirect immunoperoxidase staining technique with frozen sections of schistosome for serodiagnosis of latent schistosomiasis].

Indirect immunoperoxidase staining technique using frozen sections of adult worm as antigen (IIP-AWA) was carried out to detect antibodies against schistosome antigens (AWAb) for the diagnosis of existing infection of schistosomiasis in COPT positive cases. Sera from 229 COPT positive and 135 COPT negative cases in Shanghai County, where schistosomiasis had been eradicated for more than 5 years, were tested. Sera from 122 patients with positive stool hatching from an endemic area were served as positive controls. The positive rates of the three groups were 96.9%, 5.2%, and 100% respectively. The staining pattern of the worm sections was mainly diffused at serum dilutions 1:4 to 1:16. 149 sero-positive cases were treated with pyquiton (60 mg/kg.2d) and re-examined 1, 1.5, and 2.5 years post-treatment. The negative conversion rate of IIP-AWA was considerably higher than that of COPT (80% vs. 61.1%) at the first year, but no significant difference was observed after 2.5 years (85.5% vs. 83.6%). With the decreasing antibody titer, the staining pattern of worm sections changed from diffused to focal pattern, mostly in the gut. The results suggest that the presence of detectable AWAb in untreated patients or patients treated 2 years ago with pyquiton possibly indicate latent schistosomiasis. IIP-AWA is of practical value in screening populations for latent schistosomiasis in areas where the disease had been under control.

Animals↗
PubMed1989

Occipital transtentorial approach for removal of pineal region tumors: report of 64 consecutive cases.

A series of 64 patients with pineal region tumors operated on between 1981 and 1985 at the Beijing Neurosurgical Institute is reported. All were approached using an occipital transtentorial technique. A gross total or radical subtotal removal was achieved in 87% with a total mortality and morbidity of less than 10%. The relative advantages of this particular approach to the pineal region are discussed. It is concluded that the transtentorial approach to the pineal region provides excellent visualization and circumvents many of the pitfalls of other approaches to this region.

Adolescent↗
PubMed1988

[Primary non-Hodgkin's lymphoma of the breast--report of 8 cases].

Eight cases of primary Non-Hodgkin's lymphoma (NHL) of the breast are reported. Almost all presented as a painless movable mass without nipple retraction, edema in the overlying skin, satellite skin nodules or bloody nipple discharge. Most of the cases belonged to B cell lymphoma. Wide local excision or simple mastectomy combined with chemotherapy or radiotherapy were adopted in the treatment of these patients. The average survival was 28 months. Since prognosis of NHL is worse than that of breast carcinoma and is easily misdiagnosed as breast cancer, it is important to take vigilance in the differential diagnosis.

Adult↗
PubMedDate not supplied

Near-work activity and myopia in rural and urban schoolchildren in China.

PURPOSE: To examine the prevalence of myopia in rural and urban schoolchildren in Xiamen, China, and to assess the impact of environmental factors on rates of myopia. METHODS: Second-grade children attending either a city (n=119) or rural (n=91) school in Xiamen, China, were examined using cycloplegic autorefraction and biometry. Detailed questions on socioeconomic status, near-work activity, reading and writing habits, and family histories of myopia were asked in a face-to-face interview using a standard questionnaire. RESULTS: The prevalence of myopia was 19.3% (95% confidence interval [CI], 12.3, 29) in the city and 6.6% (95% CI, 2.4, 14.3) in the countryside. The average hours per day children spent reading and writing outside of school was 2.2 hours in the city compared with 1.6 hours in the countryside (P<.0001). In both schools, the odds ratio for total reading and writing, adjusted for parental history of myopia, was 2.2 (95% CI, 1.1, 4). CONCLUSION: These data suggest the prevalence of myopia is higher in the city than in the countryside. One possible explanation for these different rates could be that schoolchildren in the city spend more time reading and writing outside of school compared with children in the countryside. Myopic children in both the city and the countryside spent more time reading and writing compared with nonmyopic children. This increased near-work activity may contribute to the prevalence of myopia.

Child↗