Determining a 'safe' high-mass limit in matrix-assisted laser desorption/ionisation time-of-flight mass spectra of coal derived materials with reference to instrument noise

Three methods for determining a 'safe' estimate for high-mass limits of MALDI spectra of coal derived liquids were explored, using a sample of coal-tar pitch and its pyridine-insoluble fraction. Co-addition of increasing numbers of single-shot spectra (10, 30, 50 and 100 pulses) showed visually observable reductions in noise levels, consistent with robust and statistically meaningful signals. Three separate types of post-acquisition calculation were used to identify high-mass limits of the spectra. (i) A literature method indicated high-mass limits similar to those observed visually-as a shift from baseline at the highest masses, nearly 350 000 u for the coal tar pitch and about 390 000 u for its pyridine insoluble fraction. (ii) Comparing instrument signal with pre-selected multiples of the standard deviation, upper mass estimates of between 40-60 000 u for the coal-tar pitch and about 95 000 u for its pyridine-insoluble fraction were found. (iii) Calculation of the slope was used to identify 'lift-off' of the spectrum from baseline. The angle between the smoothed spectrum and the baseline was matched to a pre-selected value (e.g. 0.5 degrees and 1 degrees ). However, the arbitrary specification of the key parameter did not establish this last method on a firm basis. The choice of a criterion for estimating high-mass limits of MALDI spectra remains a semi-quantitative procedure; a reasonably conservative high-mass limit may be estimated by comparison of signal with five times the standard deviation. However, evaluation of size exclusion chromatograms of the present samples using polystyrene standards suggests that molecular mass distributions of pitch samples arrived at by MALDI mass spectrometry are, at least partly, determined by the limitations of available instruments. Copyright 1999 John Wiley & Sons, Ltd.

[Expression of bcl-2 gene in human trabecular cells induced by dexamethasone]

PURPOSE

To investigate the influence of dexamethasone on expression of bcl-2 gene in human trabecular cells.

METHODS

The trabecular specimens from human eyes were cultured in vitro and the cultured cells of the third generation on slides were immersed in culture solution containing 10(-7) M dexamethasone for 6 hours, 12 hours and 24 hours respectively. The expression of bcl-2 gene was studied with LSAB.

RESULTS

The positive cells of the bcl-2 protein could be identified after dexamethasone effected for 6 hours and the positive cell increased with time going on.

CONCLUSION

The expression of bcl-2 gene can be induced by dexamethasone, it may be related with glaucomatic pathogenesis.

Peripheral nerve and transgene cells transplantation in the treatment of experimental neuropathy of SD rats

PURPOSE

To observe whether optic nerve can regenerate by peripheral nerve transplantation and GDNF gene transfer.

METHODS

Optic nerve was transected about 2 mm posterior to the eye to establish experimental models of optic neuropathy. Sciatic nerve was sutured to the sheath of injury optic nerve by a 10-0 nylon, pcDNA3-GDNF was smeared to the joint and injected to the vitreous cavity. The regenerated retinal ganglion cells axons were observed by HRP. The retina and optic nerve were observed by pathohistological methods.

RESULTS

Some retinal ganglion cells with regenerated axons could be seen a week after transplantation with large cell bodies. The cells could be identified by HRP. The regenerated nerve fibers grew to the transplanted sciatic nerve. Then the number of retinal ganglion cells with regenerated axons increased with time going. Only a few regenerated retinal ganglion cells could be seen two months after transplantation. The large retinal ganglion cells were seen to have plenty of cytoplasms and be in an active state under electron microscope. Some nerve fibers could be seen in the joint. Sciatic nerve transplantation combined with GDNF gene therapy could increase the amount of retinal ganglion cells with regenerated axons compared with those without GDNF transgene.

CONCLUSIONS

Optic nerve could regenerate by peripheral nerve transplantation and GDNF gene transfer.

The study on culture and ultrastructure of glaucomatous trabecular cells in vitro

PURPOSE

To establish the culture system of human glaucomatous trabecular cells in vitro and study their ultrastructures.

METHODS

The trabecular specimens from trabeculectomy were cultured in vitro and passaged 3 times, then identified. Moreover, the glaucomatous cells were observed with electron microscope while compared with the normal ones.

RESULTS

Cultured human glaucomatous trabecular cells were obtained. The ultrastructure of the cells showed the decrease in vilious project, coated vesicle and lysosomal inclusion.

CONCLUSION

The establishment of human glaucomatous trabecular cells culture in vitro made the culture system more perfect. The morphologic changes might be related to the abnormal functions of human trabecular meshwork cells.

Characterization of glucocorticoid receptor on lymphocytes in Chinese patients with glucocorticoid-induced glaucoma

PURPOSE

We studied the pathogenesis of glucocorticoid-induced glucoma (GIG) through characterization of glucocorticoid receptor (GR) on lymphocytes in Chinese patients with GIG.

METHODS

By radioligand receptor binding followed by Scatchard analysis, the specific binding sites were characterized and quantitated for glucocorticoid receptors on peripheral blood lymphocytes obtained from patients with GIG and the control group.

RESULTS

The binding sites we detected were as follows: 12.7 +/- 1.47 x 10(3) receptors per cell with a KD of 3.02 +/- 0.62 nmol/L in patients with GIG, 7.26 +/- 0.45 x 10(3) receptors per cell with a KD of 3.03 +/- 0.56 nmol/L in the control group. The statistical difference of receptors per cell is significant between two groups (p < 0.05), patients with GIG having more GR binding sites, while the difference of Kd is not significant (p > 0.05).

CONCLUSION

The preliminary findings suggest that patients with GIG are more sensitive to glucocorticoid and the increase of binding sites of GR may be the receptor and molecular basis of the pathogenesis of GIG.

[The preliminary experiment of gene transfer into cultured rat retinal neural cells]

PURPOSE

To investigate the possibility of gene transfer into retina neural cells.

METHODS

pcDNA3-LacZ and pcDNA3-GDNF were transferred into rat retinal neural cells with cationic lipofectin. The gene transfer and expression of GDNF were detected by means of RT-PCR and SDS-PAGE.

RESULTS

pcDNA3-LacZ and pcDNA3-GDNF could be transferred into retinal neural cells and the expressive product of GDNF gene, a 32 KD protein band, was detected.

CONCLUSION

The preliminary results suggest that LacZ gene could be a marker to identify gene transfer into the target tissue and cells; GDNF gene could be transferred into cultured retinal neural cells of SD rats, and express 32 KD protein.

Laparoscopic retroperitoneal lymph node dissection in clinical stage I nonseminomatous germ cell tumor: a minimal invasive alternative

OBJECTIVE

To evaluate modified laparoscopic retroperitoneal lymph node dissection (LRPLND) performed for stage I nonseminomatous germ cell tumor.

METHODS

Between December 1993 and January 1996, modified unilateral laparoscopic retroperitoneal lymph node dissection was performed on 13 patients with nonseminomatous germ cell tumor of the testis. In 8 patients, the tumor was on the right side, and in 5, on the left.

RESULTS

The procedure was completed in 12 patients at a mean operating time of 292 min (range: 210-400 min). The mean estimated blood loss was 250 ml. The mean hospital stay was 6.4 days. Conversion to open surgery was required in one patient because of an uncontrollable venous bleeding. No other major complications occurred. Antegrade ejaculation was preserved in 10 patients, and the last 3 patients have not yet been addressed now.

CONCLUSIONS

Our results demonstrate that LRPLND is an accurate and reliable staging procedure with low morbidity, which allows quick patient discharge and rapid return to normal activity. For further evaluation, long follow-up in larger groups of patients is required.

[The study on the culture, freezing preservation and resuscitation of human trabecular cells in vitro]

PURPOSE

To establish the culture of human trabecular cells in vitro and study the freezing preservation and resuscitation.

METHODS

The trabecular specimens from human eyes were cultured in vitro and passaged 3 times, then the cultured cells were frozen and preserved. The frozen cells were resuscitated after one week, two weeks, one month and two months.

RESULTS

Cultured human trabecular cells were obtained. The frozen cells were resuscitated successfully. All of the resuscitated rates were more than 90%.

CONCLUSION

The human trabecular cells were cultured in vitro successfully, they can also be frozen and resuscitated, which will be helpful to the establishment of cDNA library and the screening of associated glaucomatous genes.

[The study of the biological character on the culture of human trabecular meshwork cells in vitro]

PURPOSE

To establish the culture of human trabecular cells in vitro and to study their biological character.

METHOD

The trabecular specimens from human eyes were cultured. The morphologic features of cultured cells were examined by light and electron microscopy, the immunohistochemical characteristics and the proliferative curve of the cultured cells were also investigated.

RESULTS

The primary cells in culture are multiangular or irregular, and the confluent trabecular cells grow as a single cell layer. The junctions between trabecular cells observed most frequently are puncta adherens and gap junction. Trabecular cells showed apical villons projections and had a high density of various organelles. The trabecular cells were stained intensely with monoclone antibodies to fibronection and laminin and NSE. And it had negative reaction to monocolone antibodies to VIII factor. The cultured cells showed a longer doubling time.

CONCLUSION

The culture of human trabecular cells in vitro was established. This was a key step to dissect the trabecular specimen accurately and carefully. According to the different cellular growth patterns and speed, morphologic and immunohistochemical characteristics from that of the near cells, the cultured human trabecular cells can been identified.

The dynamics of aging and mortality in the People's Republic of China, 1957-1990

The Strehler-Mildvan modification of the Gompertz relationship between aging and mortality predicts a negative linear relationship between the theoretical logarithm of the mortality rate at birth (log R0) and the exponential rate of increase (alpha) in the age-specific mortality rates under specified conditions. This prediction has been generally validated using mortality data from the United States with respect to general and many disease-specific age-specific mortality rates by the method of longitudinal Gompertzian analysis. Estimated age-specific mortality rates from the People's Republic of China for seven years from 1957 to 1990 were analyzed using the method of longitudinal Gompertzian analysis. The results in this population further validate the Strehler-Mildvan modification of the Gompertz relationship between aging and mortality.

Serum lipids and their correlates in Chinese urban and rural populations of Beijing and Guangzhou. PRC-USA Cardiovascular and Cardiopulmonary Epidemiology Research Group

In 1983 and 1984, surveys were conducted in four Chinese population samples, urban and rural for both Beijing and Guangzhou, as part of PRC-USA collaborative research in cardiovascular and cardiopulmonary epidemiology. Serum total cholesterol (TC), HDL-cholesterol (HDL-C), and triglycerides (TG) were measured in 4280 men and 4695 women aged 35-54 years, in laboratories standardized by the US Centers for Disease Control. Age-adjusted mean serum TC was higher in urban than rural samples and generally higher in Beijing than Guangzhou, ranging from 155 mg/dL for Guangzhou rural women to 187 mg/dl for Guangzhou urban women. Group mean values of HDL-C varied from 48 to 59 mg/dl, higher in Beijing than Guangzhou, and higher in women than men. TC/HDL-C ratio ranged from 3.05 to 3.82. Serum TG values were higher for Beijing than Guangzhou; the lowest group mean values of 78 mg/dl and 75 mg/dl were in rural Guangzhou men and women. Mean body mass index (BMI) was uniformly low, ranging from 20 kg/m2 for rural Guangzhou to 24 kg/m2 for urban Beijing. Multiple regression analyses showed that BMI was positively and independently related to serum TC, LDL-C, TG, and TC/HDL-C, and inversely related to HDL-C. Smoking was positively related in both sexes to TG and TC/HDL-C, and inversely related to HDL-C. Smoking was also positively related to TC and LDL-C in men. In men, alcohol was positively related to TC and HDL-C, and was inversely related to TG and TC/HDL-C. Heavy manual work was inversely related to TC, LDL-C, and TC/HDL-C in men, but not related to lipids in women. Thus, for these Chinese population samples, despite their lower serum TC and BMI, the correlates of serum lipids are similar to those in western populations. These variables accounted for only part of the observed urban-rural and north-south differences in serum lipids among these Chinese population samples. The significance of the relatively low serum TC and TG and high HDL-C in relation to low cardiovascular disease in Chinese populations is the object of further investigation in follow-up studies.