Enhanced sensitivity for sequence determination of major histocompatibility complex class I peptides by membrane preconcentration-capillary electrophoresis-microspray-tandem mass spectrometry

Sequence analysis of antigenic major histocompatibility complex (MHC) class I peptides requires minimizing sample loss and enhancing mass spectrometric sensitivity. In order to facilitate such analyses, we have coupled on-line membrane preconcentration-capillary electrophoresis (mPC-CE) with microspray mass spectrometry (mPC-CE-microMS) and tandem mass spectrometry (mPC-CE-microMS/MS). Specifically, cell lysate from approximately 10(9) EG-7 mouse tumor cells was immunoprecipitated and the released MHC class I peptides were subjected to reverse-phase HPLC. An HPLC fraction containing antigenic peptide(s) shown to induce T-cell stimulation was subjected to mPC-CE-microMS. Approximately 10 microL (from 100 microL) of the fraction was pressure-injected and concentrated on a styrenedivinylbenzene (SDB) impregnated membrane. The peptides were eluted from the membrane with approximately 100 nL of 80% methanol, sandwiched between a leading stacking buffer (LSB, also serving as CE separation medium) of approximately 110 nL of 0.1% acetic acid in 10% methanol, and a trailing stacking buffer (TSB) of approximately 110 nL of 0.1% NH4OH. On application of the CE voltage the peptides are subjected to moving boundary transient isotachophoresis and focused. The peptides were separated in a Polybrene-coated capillary with application of -20 kV in reverse polarity mode and subsequently sprayed via an emitter coupled to the CE capillary by a liquid junction containing a platinum wire. An ion at m/z 482.3 was detected and subjected to mPC-CE-microMS/MS and determined to be SIINFEKL, a peptide (OVA) known to be antigenic in the mouse model system. Sensitivity enhancement over conventional mPC-CE-MS and MS/MS was approximately 100-fold.

[Cell density and expression of proliferating cell nuclear antigen (PCNA) in the lens epithelium of children and aging patients with cataract]

OBJECTIVE

To determine the cell density and expression of proliferating cell nuclear antigen (PCNA) in the lens epithelium of children and aging patients with cataract.

METHODS

The lens epithelial cells (LECs) of the central area were examined in two groups, children (less than 12 years old) and senile persons (51 - 80 years old). The densities of LECs in the two groups were calculated with samples stained with hematoxylin and eosin (HE) staining, and the PCNA was tested immunohistochemically. The integral optical density (IOD) of PCNA expression was measured through a medical color image analysis system.

RESULTS

The densities of LECs in children and senile persons were 5,020.25 +/- 246.01 cells/mm(2) and 4,340.00 +/- 240.95 cells/mm(2) (P < 0.05), the IODs were 2.89 +/- 0.57 and 2.13 +/- 0.63 (P < 0.05) respectively.

CONCLUSION

The LEC counting and IOD values in children eyes are significantly higher than that of senile persons, suggesting that they be one of the important factors in the formation of posterior capsular opacification (PCO) or after cataract in children eyes.

[Studies on effects of yttrium chloride and praseodymium chloride on frequency of micronucleus in human blood lymphocytes]

OBJECTIVE

To explore genotoxicity of rare-earth elements, yttrium and praseodymium.

METHODS

Effects of yttrium chloride and praseodymium chloride on human lymphocytes cultured in vitro were studied by micronucleus test.

RESULTS

Frequency of micronucleus in human blood lymphocytes increased significantly by treatment with yttrium chloride and praseodymium chloride, and it increased with the concentration of the both agents, to a certain range.

CONCLUSION

It suggests that rare-earth elements yttrium and praseodymium have certain genotoxicity.

Polydactyly and ectopic ZPA formation in Alx-4 mutant mice

Correct development of the limb is dependent on coordination between three distinct signaling centers. Recently, fibroblast growth factor-4 has been identified as a crucial determinant of AER function, which directs limb bud outgrowth, and Sonic hedgehog has been identified as a signaling molecule that mediates ZPA function, which specifies anterior-posterior patterning in the developing limb bud. In addition, Shh and FGF-4 reciprocally reinforce each other's expression via a positive feedback loop, providing a molecular basis for the coordination of limb bud outgrowth and anterior-posterior patterning. The mechanisms by which these signaling centers come to occupy their normal positions in the posterior limb bud during development are not understood. Here we identify and characterize Alx-4, a gene that encodes a paired-type homeodomain protein. Alx-4 is expressed in several populations of mesenchymal cells, including mesenchymal cells in the anterior limb bud, and mice homozygous for targeted disruption of the Alx-4 gene have multiple abnormalities, including preaxial polydactyly. The polydactyly is associated with the formation of an ectopic anterior ZPA, as indicated by anterior expression of Sonic hedgehog, HoxD13 and fibroblast growth factor-4. The expression of other candidate regulators of anterior-posterior positional information in the limb bud, including HoxB8 and Gli3, is not altered in Alx-4 mutant embryos. By chromosomal mapping experiments, Alx-4 is tightly linked to Strong's luxoid, a polydactylous mouse mutant. The results identify Alx-4 as a determinant of anterior-posterior positional identity in the limb and a component of a regulatory program that restricts ZPA formation to the posterior limb bud mesenchyme.

[Accumulation and excretion of fluorine and effect of selenium on them in rats with chronic fluorosis]

2 groups of Wistar rats with chronic fluorosis were duplicated with 30 and 50 mg/L fluorine (F) in drinking water. 2. 0 mg/kg selenium (Se) in fodder was supplemented in the other 2 groups of rats with fluorosis. The amount of drinking water and diet, the excretion of urine and the contents of urine F were tendentiously surveyed every month in one year and then, intake and excretion of F were calculated per day. The contents of Se in urine, liver and serum and F in bone, liver, kidney and serum were measured in the 4th, 8th, and 14th month. The results showed that F absorption increased and F excretion/F absorption rate decreased in 2 groups of rats with fluorosis compared with control group and there were positive correlations between concentration of urine F and water F, as well as concentration of F urine and time of drinking F water. The accumulation of F in bone and liver occurred in the middle period of fluorosis and then, the increase of serum F was observed in the late period of fluorosis in 2 groups of rats with fluorosis. After supplement of Se, urine, liver and serum Se ascended. At the same time, state of eating and drinking improved, the weight rose and the amount of urine excretion heightened, as well as there was an increase of urine F and excretion F/absorption F rate and there was a decrease of bone, live, kidney and serum F in rat of Se supplementation with fluorosis compared with non-Se groups.

[Localization of PTH gene on pig chromosome 14q25-q28 by in situ hybridization]

The human parathyroid hormone (PTH) genic DNA, as a probe, was labelled with tritium(3H) using nick translation and random oligonucleotide primers methods. Metaphase chromosomal G-bands were prepared from cultured blood lymphocytes of domestic pig. After in situ hybridization and autoradiographly, the number of silver grains on every chromosome was calculated. The result showed that PTH gene is located at chromosome 14q25-q28. The relevent points of this study are discussed.

[Factors affecting prognosis of papillary thyroid carcinoma with bilateral cervical lymph node metastases]

One hundred thirty nine cases of papillary thyroid carcinoma with bilateral lymph node metastases were reviewed. They were surgically treated at the Cancer Hospital of Shanghai Medical University in the years from 1956 through 1990. There were 73 men and 66 women with a median age of 35 (range 11-70) years. The median follow-up period was 11 years. Kaplan-Meier survival curves were calculated for the population. The overall survival rate was 94.7% at 5 years, 85.9% at 10 years, and 82.3% at 15 years. In univariate analysis, factors influencing prognosis are age at diagnosis, tumor size, extrathyroidal invasion, residual tumor and thoroughness of excision. When Cox proportional risk model was applied to analyze the survival data, factors of survival significance are the age at diagnosis and thoroughness of excision.

Method for the design of broad energy range focusing reflectrons

A novel method for the design of reflections capable of focusing large kinetic energy ranges is presented. The design method itself is a numerical approach that provides a geometrically flexible alternative to traditional analytical design solutions. This design method has been used to produce a reflectron that provides unit mass resolution for product spectra in a tandem reflectron time-of-flight (TOF) mass spectrometer despite a kinetic energy range of 1950-2700 eV. In this application, the systematic progression of reflectron design results in a practical, nonlinear field reflectron with the use of only two grids. Design improvements are proposed for more flexible systems, although geometric constraints in the current instrument limit their experimental evaluation.

A segmented ring, cylindrical ion trap source for time-of-flight mass spectrometry

An ion trap source has been designed for use with time-of-flight (TOF) mass analysis. Two thin diaphragms make up a segmented ring electrode; the end cap electrodes are planar wire mesh. The potential field produced by the rf voltage applied between the ring and end cap electrodes resembles that of the cylindrical ion trap. The trapped ion population for ions created by electron impact exhibits linear growth against a first-order loss that has a time constant of about 50 µs; no ion loss occurs when the electron beam is off. The observed value of q z at low-mass cutoff for rf ion storage is -0.84. Pulsed extraction of all ions is accomplished by switching the trap electrodes from rf to voltages required to provide a linear dc extraction field. The TOF flight path includes a wide energy range reflectron. Better than unit mass resolution is achieved through m/z 500 without collisional ion cooling. With an extraction rate of 1 kHz and a recording rate of 4 spectra per second, a linear working curve is obtained between 36 pg and 18 ng of chlorobenzene delivered chromatographically. The system has demonstrated the potential to achieve a very high sample utilization efficiency at high spectral generation rates.

Vicia faba root tip micronucleus test on the mutagenicity of water-soluble contents of cigarette smoke

The possible mutagenicity of the water-soluble contents of cigarette smoke (WSCS) was evaluated by using the Vicia faba root tip micronucleus test. The results showed significant changes in micronucleus frequency which were caused by each different concentration of WSCS. This indicates that the Vicia faba root tip micronucleus test might be used as one kind of mutagenic detection method for cigarette smoke. A comparative evaluation on the mutagenicity of 10 brands of cigarettes was carried out. Results confirmed that various degrees of mutagenicity were found for all of the brand cigarettes, among them, Huaihai was the highest, while Camellia was the lowest. The micronucleus frequencies were reduced by adding tea polyphenol, nicotinamide adenine, vitamin C and sodium selenite to the WSCS. The results suggest that these added substances might reduce the genetic injury induced by cigarette smoke.