Computer simulation of random packing of unequal particles

A Monte Carlo simulation model for the random packing of unequal spherical particles is presented in this paper. With this model, the particle radii obeying a given distribution are generated and randomly placed within a cubic packing domain with high packing density and many overlaps. Then a relaxation iteration is applied to reduce or eliminate the overlaps, while the packing space is gradually expanded. The simulation is completed once the mean overlap value falls below a preset value. To simulate the random close packing, a "vibration" process is applied after the relaxation iteration. For log-normal distributed particles, the effect of particle size standard deviation, and for bidisperse particles, the effects of particle size ratio and the volume fraction of large particles on packing density and on coordination number are investigated. Simulation results show good agreement with that obtained by experiments and by other simulations. The randomness, homogeneity, and isotropy, which have not been evaluated before for packing of distributed particles, are also examined using statistical measures.

[Relationship between glutathione S-transferase M1, T1 genotype and susceptibility to gastric cancer]

OBJECTIVE

The objective of this study was to examine the association between glutathione s-transferase M1, T1 genotype and the risk of gastric cancer.

METHODS

A case-control study was carried out and polymerase chain reaction (PCR) technique was used to identify GST M1, GST T1 genotype in 95 cases of primary gastric cancer and 94 controls.

RESULTS

The frequency of GST M1 null genotype was 63.16% and 45.74%, respectively in gastric cancer cases and control group, with statistically significant difference (chi(2) = 5.75, P = 0.0165). GST M1 null genotype correlated with the susceptibility to gastric cancer (OR = 2.03, 95% CI of OR = 1.09 - 3.80). The risk for gastric cancer in those with GST M1 null and GST T1 non-null genotype was significantly higher than that in those with GST M1 non-null and GST T1 null genotype, with an OR of 2.91 and 95% CI of ORs 1.09 - 7.89. The risk for gastric cancer in those smoking with GST M1 null genotype increased significantly (OR = 8.06, 95% CI of OR = 2.83 - 23.67).

CONCLUSION

GST M1 null genotype was associated with the risk for gastric cancer.

Tumor necrosis factor-alpha mediates lipopolysaccharide-induced macrophage inflammatory protein-2 release from alveolar epithelial cells. Autoregulation in host defense

Our recent studies have demonstrated that in response to lipopolysaccharide (LPS) challenge, alveolar epithelial cells produced tumor necrosis factor (TNF)-alpha, an early response cytokine in the inflammatory process. To investigate whether LPS-induced TNF-alpha release is related to other inflammatory mediators from the same cell type, we examined effects of LPS stimulation on macrophage inflammatory protein (MIP)-2 production by alveolar epithelial cells, and then examined the relationship between TNF-alpha and MIP-2 production. LPS stimulation induced a dose- and time-dependent release of MIP-2. The steady-state messenger RNA level of MIP-2 was significantly increased, with the MIP-2 protein localized within alveolar epithelial cells, as determined by confocal microscopy. The LPS-induced MIP-2 production is regulated at both the transcriptional and post-transcriptional levels. TNF-alpha also induced MIP-2 production from alveolar epithelial cells. Preincubation with an antisense oligonucleotide against TNF-alpha inhibited LPS-induced TNF-alpha in a dose-dependent and sequence-specific manner. The same antisense also inhibited MIP-2 production. The inhibitory effects were highly correlated. Polyclonal and monoclonal antibodies against TNF-alpha also attenuated LPS-induced MIP-2. These results suggest that LPS-induced MIP-2 release from alveolar epithelial cells may be mediated in part by TNF-alpha from the same cell type. This autoregulatory mechanism may amplify LPS-induced signals involved in host defense as well as in acute inflammatory reactions.

[Distribution of 5-fluorouracil in plasma and pancreatic tissue of rats during the regional arterial infusion chemotherapy]

OBJECTIVE

Compare the pharmacokinetic parameters of 5-FU in the regional arterial infusion chemotherapy with those in the intravenous chemotherapy.

METHODS

Wistar rats were randomly divided into two groups: the intravenous group and the regional arterial infusion group. HPLC was used to measure the concentration of 5-FU in the plasma and the pancreas tissue. Penetration index was calculated.

RESULTS

In the intravenous group, maximum concentration (Cmax) of 5-FU in the pancreas was 8.42 micrograms/g and the clearance time of the pancreas was 50 min. In the regional arterial infusion group, Cmax of 5-FU in the pancreas was 20.00 micrograms/g and the clearance time of the pancreas was 90 min. They were both greater than those of the intravenous group. Rd was 2.42.

CONCLUSIONS

The regional arterial infusion chemotherapy is a better way for treating pancreatic carcinoma than the intravenous chemotherapy.

Improved metastatic animal model of human prostate carcinoma using surgical orthotopic implantation (SOI)

BACKGROUND

An animal model demonstrating high metastasis of human prostate carcinoma is of importance in studying the biology and therapy of human prostate carcinoma Dr. Hoffman's group recently used surgical orthotopic implantation (SOI) of human prostate cells to nude mice to establish an animal model with high metastatic activity. To confirm the animal model by SOI reproducible in other laboratories and shorten the period requiring for the metastasis, we adopted SOI technique with a modification using PC-3M human prostate cell line which showed a higher metastatic activity than PC-3.

MATERIALS AND METHODS

Intact tissue of the human prostate carcinoma cell line PC-3M was prepared by growth of this cell subcutaneous in a nude mouse. One piece of 1.5 mm3 intact tumor tissue was implanted by orthotopical surgery to the ventral lateral lobes of the prostate gland of 10 nude mice. Mice were sacrificed when they were found to be moribund. Metastasis in other tissues was evaluated by gross and microscopic morphology.

RESULTS

All 10 mice showed the tumorigenesis in the prostate gland and metastasis of human prostate tumor cells into periaortic lymph nodes without other organ's metastasis. The time when mice with PC-3M SOI start moribund is 28-32 days after SOI.

CONCLUSIONS

SOI is good technique to establish the efficiently metastatic animal mode. SOI using PC-3M human prostate cell line will leads to 100% metastasis of prostate tumor cells. So far, this model is much quicker and more efficient than those reported in literatures.

The diagnosis and treatment of gastrinoma: report of 17 cases

OBJECTIVE

To study the experience of diagnosis and treatment of gastrinoma.

METHODS

A retrospective study of 17 patients with gastrinoma seen from 1978 through 1998 in PUMC hospital.

RESULTS

Three of the 17 cases were associated with multiple endocrine neoplasia type I (MEN-I) syndrome. Tumors dispersed extensively in pancreas (31%), duodenum (25%), lymphnode (19%) and other place (25%). Ultrasonography and computed tomography (CT) were sensitive in localizing tumor in pancreas and liver, but were not so well for small tumor in duodenum and lymph node. The angiography, percutaneous transhepatic portal sampling (PTPS), scintigraphy and endoscopic ultrasonography (EUS) also can be used. Sixteen of 17 patients underwent 38 operations and 56 percent of the 16 cases underwent several operations. Seven patients at last performed total gastrectomy that was still considered as a choice of treatment. Tumor resection was rare because the advancing of tumor in most cases.

CONCLUSIONS

Diagnosing gastrinoma in its early stage and striving for the tumor resection and reducing the metastasis of liver were the cruxes for good prognosis.

Optical readout for optical storage with phase jump

A novel, to our knowledge, optical readout for optical storage with phase jump is presented. In the readout scheme two coherent laser beams are focused on an optical disk with one beam scanning along pits and the other along land. When the probe beam scans across a pit, two phase jumps will take place in the interference resultant of the two beams if the phase difference between two beams is prefixed at pi, resulting in a phase pulse of 180 deg. The slopes of rising and falling edges of the phase pulse are infinite, and they are not affected by the intensity variation of the light source, stray light, and the vibration of the disk. Therefore this phase pulse can be used to read out the information on an optical disk. The use of phase jump will improve the signal-to-noise ratio of the readout signal and enhance the density of optical storage. An optical readout with phase jump was constructed. Both the theoretical design and the experimental verification are conducted. Experimental results show that the proposed optical readout is feasible.

Relatively low-dose cyclophosphamide is likely to induce apoptotic cell death in rat thymus through Fas/Fas ligand pathway

Cyclophosphamide (CPA) is widely used as an efficiently antineoplastic drug, but also causes immunosuppression as its adverse-side effect. To understand the effect of low- or relative low-dose CPA on the immune system, apoptotic cell death in rat thymus, either exposed to different doses of CPA (0, 2, 7, 20 and 70 mg/kg) for 12 h or exposed to 70 mg/kg for different times (4-48 h), was investigated by DNA fragmentation (DNA ladder) detection and in situ morphological examination using hematoxylin and eosin (H and E) staining. Immunohistochemical staining for Fas protein expression in the thymus of rats exposed to CPA was performed. Results showed that exposure of rats to CPA 0-70 mg/kg for 12 h did not cause significant decrease in the ratio of thymus weight to body weight. However, the ratio of thymus weight to body weight was decreased significantly at 48 h after exposure to 70 mg/kg CPA. Exposure to 20 and 70 mg/kg CPA for 12 h caused a visible DNA ladder in gel electrophoresis. DNA ladder formation was increased progressively in the groups from 8 h to optimal magnitude at 12-24 h and then disappeared at 48 h after 70 mg/kg CPA. This pattern was confirmed by a quantitative evaluation of the apoptotic cells using H and E staining. Expression of Fas protein was enhanced in the thymus of rats exposed to 70 mg/kg CPA for 4-8 h as compared to control rats. These results are different from previous studies on high dose CPA and the induction of the apoptotic cell death in thymus by low or relative low doses of CPA might be a result of Fas/Fas-ligand interactions.

[Hyphenation of capillary electrophoresis with nuclear magnetic resonance and its applications]

Direct on-line coupling between capillary electrophoresis and nuclear magnetic resonance spectroscopy (CE-NMR) is one of the most powerful and novel techniques for simultaneous separation and structural elucidation of biomacromolecules. Recent advances and the most crucial technique of measuring samples on nanoliter scale in CE-NMR are described in detail.

Increased radiation-induced apoptosis in mouse thymus in the absence of metallothionein

Metallothionein (MT) has been shown to protect cells from free radical induced DNA damage after exposure to copper, hydrogen peroxide and also radiation. In order to study the role of MT in radiation induced apoptosis, age-matched male control mice (C57BL/6J), MT-I overexpressing (MT-I*) and MT-null transgenic mice were exposed to whole body cobalt 60 gamma-irradiation at 0, 5, or 10 Gy, and their thymus were removed 24 h later. The basal levels of MT and zinc concentrations in the thymus were measured by 109Cadmium-heme assay and atomic absorption spectrophotometry, respectively. The MT expression after radiation was determined by immunohistochemical staining using a polyclonal antibody to MT. The extent of apoptosis in thymocytes was determined by histology (H&E stain). DNA was isolated from the thymus, and DNA fragmentation was determined by agarose gel electrophoresis. The results showed that the basal level of MT protein in MT-I* thymus was 2.4-fold higher than control mice, and that MT was inducible in both MT-I* and control C57BL6 thymus after radiation exposure. Minimal MT protein was detected in MT-null mice thymus before or after radiation, while, a significantly higher number of apoptotic cells and DNA fragmentation were found in MT-null thymus after whole body irradiation. These data demonstrated a protective role for MT in radiation-induced apoptosis in mouse thymus.

Endothelins and their receptors in cirrhotic and neoplastic livers of Canadian and Chinese populations

BACKGROUND

Endothelins (ETs) are 21 amino acid peptides with widespread tissue distribution and functions. In this study, we retrospectively investigated immunoreactive ET-1, ET-3 as well as ET receptors by ligand binding and autoradiography in hepatic cirrhosis and neoplasms.

MATERIALS AND METHODS

Formalin fixed paraffin embedded tissues from 30 hepatocellular carcinomas (HCC), 4 fibrolamellar carcinomas (FLC), and 7 liver metastatic adenocarcinomas (Ad) from colon were collected from the Pathology Department of London Health Science Centre. Adjacent cirrhotic livers were obtained from 17 cases and adjacent normal liver was present in 12 cases. In addition, 15 HCCs, 6 cirrhotic and 8 normal livers were obtained from Normal Bethune University for Medical Sciences in China. The slides were stained for ET-1 and ET-3 with a polyclonal antibody and scored. Autoradiographic localization of ET-receptors with 125I-ET-1 was carried out in some of the cases.

RESULTS

In the normal liver, hepatocytes, biliary epithelium, vascular endothelium and smooth muscle cells were positive for both ET-1 and ET-3. Higher immnunoreactivity for ET-1 and ET-3 was seen in cirrhosis. HCCs showed variation in immunoreactivity, with overall scoring not different from normal livers. FLCs showed consistent higher immunoreactivity for both ET-1 and ET-3, while in Ads the immunoreactivity was decreased. Increased ET-receptors, representing both ETA and ETB subtypes were seen in both cirrhosis and in HCC.

CONCLUSION

Alterations in both ETs and their receptors were found in cirrhosis and neoplastic liver diseases.

Preparation and Characterization of Nanoscopic Organic Semiconductor of Oxovanadium Phthalocyanine

Nanoscopic particles of oxovanadium phthalocyanine (VOPc, phase-II) with different particle sizes are prepared by aggregation of VOPc molecules in the presence of surfactants for the first time. A size effect in the region of nanoscale was observed in the UV-visible spectra. The photoconductivity of the nanoscopic VOPc is much higher than that of bulk VOPc. Copyright 1999 Academic Press.

Identification of a novel cardiac lineage-associated protein(cCLP-1): A candidate regulator of cardiogenesis

We describe the isolation and characterization of a cDNA clone, called cCLP-1, that is a candidate for the previously described early cardiac-specific transcription factor BBF-1. BBF-1 binds the MEF2 (or element B) binding site within the cardiac myosin light chain 2 (MLC2) gene promoter. We used the element B sequence as a probe to screen an expression library constructed from mRNA obtained from the presumptive heart-forming regions of stage 6 chicken embryos. This yielded the cCLP-1 cDNA clone. Gel-shift analysis of stage 6 embryonic chicken protein extracts suggests that a protein that is recognized by the anti-cCLP-1 antibody binds to the same element B binding site to which BBF-1 binds. cCLP-1 mRNA was detected early in chicken development, prior to cardiac fate assignment at stage 4. The expression pattern of cCLP-1, based on whole mount in situ hybridization, coincides remarkably well with the established morphogenetic field of early heart formation. The nuclear localization of cCLP-1 is phosphorylation-dependent, suggesting that cCLP-1 may be a member of that class of transcription factors whose activity is regulated by cytoplasm to nucleus transport. Taken together, these data suggest that cCLP-1 may encode a novel transcription factor whose expression pattern is in agreement with that of the cardiogenic precursor cells of the early chicken embryo.

[Apoptosis of human pancreatic carcinoma cell lines induced by combinations of chemotherapeutic drugs]

OBJECTIVE

To investigate the apoptotic in human pancreatic carcinoma cell lines P3, SW1990 and Capan-2 induced by the combined treatment of 5-fluorouracil (5FU), mitomycin C (MMC), carboplatin(CBP) or adriamycine (ADM) or epirubicin (E-ADM).

METHODS

The changes of cell morphology were monitored by means of microscopic and fluorescence technique after treated with the combinations of chemotherapeutic drugs. The rate of apoptosis was calculated with flow cytometry and the fragmentation of DNA was measured by agarose gel electrophoresis.

RESULTS

The combinations of chemotherapeutic drugs were able to induce the apoptosis of human pancreatic carcinoma cell lines. Compared with the cell necrosis, the dosage of drugs was less and the time was shorter for inducing apoptosis. With the increased dosage and/or the time prolonged for treating the cells, the rate of apoptotic cells was increased. However, the apoptosis reaction of various human pancreatic carcinoma cell lines, which were mentioned above, induced by the same combinations of chemotherapeutic drugs were various different.

CONCLUSIONS

The apoptosis process might be a mechanism of an inhibiting cancer cell growth induced by the combinations of chemotherapeutic drugs. The examination of apoptosis reaction for the cells induced by different methods and/or chemotherapeutic drugs could become an important index of testing their ability of inhibiting pancreatic neoplasm.

Low-dose whole-body irradiation induces alteration of protein expression in mouse splenocytes

In previous studies, the stimulatory effect on immunological function and adaptive response in splenocytes were found after exposure of mice to low-dose whole-body irradiation (LD-WBI). Protein synthesis was found to be required for these responses. The present study, therefore, attempts to investigate the protein changes in mouse splenocytes after exposure to LD-WBI. Two-dimensional gel electrophoresis was used to show the alterations of proteins in nuclei, cytoplasm and extracellular fluid of the splenocytes at 4 h after mice exposed to 75 mGy X-rays. As compared to control, changed expressions of 20, 15 and 6 proteins, in sizes ranging from 10 to 69 kDa with pI of 5.0-8.2, were found in the nuclei, cytoplasm and extracellular fluid of splenocytes, respectively. One protein, shown in the cytoplasm of splenocytes of control mice, appeared in extracellular fluid of splenocytes after LD-WBI. Two proteins, shown in cytoplasm, and one protein, shown in extracellular fluid of splenocytes in control mice, appeared in the nuclei after LD-WBI. Time-course of protein synthesis varied in different proteins after LD-WBI. These results suggest that alterations of protein expressions and redistribution of proteins between intracellular and extracellular compartments occurred in the splenocytes after LD-WBI. Protein extract from LD-WBI splenocytes was fractionated by Sephadex G-100. Fractions 61-80 contained proteins able to protect lymphocytes in vitro from radiation-induced chromosome aberrations. These findings are of importance in elucidating mechanisms of immuno-enhancement and adaptive response induced by low-dose radiation. although the features and the functions of these proteins remain to be elucidated in future studies.

[Clinical and experimental study on the treatment of endometriosis with dan'e mixture]

OBJECTIVE

To find a medicine to treat endometriosis effectively with less side-effect.

METHODS

Dan'e mixture (DEM, consists of Radix Salviae Miltiorrhizae and Rhizoma Zedoariae) was used to treat 189 cases of endometriosis and the change of symptom and sign, the B ultrasonograph, the anti-endometrium antibody and endometriosis quantitative diagnostic index were observed, another 160 cases were treated with Danazol as control, also using animal model to treat with DEM and Danazol.

RESULTS

One hundred and eighty-nine cases were treated for 9 months. According to National Standards, 39 cases (20.6%) were cured, 67 cases (35.4%) were markedly effective, 67 cases (35.4%) were effective, and 16 cases (8.4%) were ineffective. Compared with 160 cases treated with Danazol for 9 months, the total effective rates were 95% and 91.5% respectively, the difference between them was insignificant. Animal experiments showed the similar results to the clinical ones.

CONCLUSION

SZM is a safe and effective medicine to treat endometriosis, which deserves further study and development. It is particularly helpful for diagnosis, treatment and prevention of endometriosis in the early stage.

Improved angle interferometer based on total internal reflection

We describe an improved interferometer for angle measurement based on the internal reflection effect. The improvement is achieved by eliminating the influence of wave-plate rotation on the measurement. In the proposed angle interferometer the wave plate is fixed and placed between a rhomb assembly and a retroreflector. This scheme not only allows the angle interferometer to keep the optical configuration compact but also doubles the resolution and can measure the pitch and yaw of moving objects. Both a theoretical analysis and an experimental verification have been conducted on the interferometer. The results indicate that the performance of the modified angle interferometer is greatly improved, especially when the rotation angle is large. The nonlinearity error of the measurement equation is also addressed.

Ventricular excitation maps using tissue Doppler acceleration imaging: potential clinical application

OBJECTIVES

The purpose of this study is to validate the use of tissue Doppler acceleration imaging (TDAI) for evaluation of the onset of ventricular contraction in humans.

BACKGROUND

Tissue Doppler acceleration imaging can display the distribution, direction and value of ventricular acceleration responses to myocardial contraction and electrical excitation.

METHODS

Twenty normal volunteers underwent TDAI testing to determine the normal onset of ventricular acceleration. Two patients with paroxysmal supraventricular tachycardia and 30 patients with permanent pacemakers underwent introduction of esophageal and right ventricular pacing electrodes, respectively, and were studied to visualize the onset of pacer-induced ventricular acceleration. Eight patients with dual atrioventricular (AV) node and 20 patients with Wolff-Parkinson-White (WPW) syndrome underwent TDAI testing to localize the abnormal onset of ventricular acceleration, and the results were compared with those of intracardiac electrophysiology (ICEP) tests.

RESULTS

The normal onset and the onset of dual AV node were localized at the upper interventricular septum (IVS) under the right coronary cusp within 25 ms before the beginning of the R wave in the electrocardiogram (ECG). In all patients in the pacing group, the location and timing of the onset conformed to the positions and timing of electrodes (100%). In patients with WPW syndrome, abnormal onset was localized to portions of the ventricular wall other than the upper IVS at the delta wave or within 25 ms after the delta wave in the ECG. The agreement was 90% (18 of 20) between the abnormal onset and the position of the accessory pathways determined by ICEP testing.

CONCLUSIONS

These results suggest that TDAI is a useful noninvasive method that frequently is successful in visualizing the intramural site of origin of ventricular mechanical contraction.

[Effect of preoperative chemotherapy on apoptosis and tissues of pancreatic adenocarcinoma]

OBJECTIVE

To investigate the apoptosis and tissues change of pancreatic adenocarcinoma with or without preoperative chemotherapy and discuss the effect of preoperative regional chemotherapy on pancreatic adenocarcinoma cell.

METHODS

Using the method of TUNEL and microscope, we determined the apoptosis of tumor cells and tissues changes in 30 pancreatic adenocarcinoma patients with or without preoperative chemotherapy.

RESULTS

The ratio of apoptosis was much higher in the preoperatively treated group than in the untreated group (44.87 +/- 27.78) and (3.6 +/- 3.76)/HP, (P < 0.01). The ratio of apoptosis was related to the tissue type of pancreatic adenocarcinoma. The ratio of apoptosis in the highly differentiated adenocarcinoma group was much higher than that in the middle or low differentiated adenocarcinoma group (P < 0.05, P < 0.01). The inflammatory reaction and the proliferous intima of vessels were more obvious in the preoperatively treated group than in the untreated group (P < 0.05, P < 0.01).

CONCLUSIONS

Preoperative regional chemotherapy can effectively inhibit pancreatic adenocarcinoma by inducing the apoptosis of tumor cells.

[The effect of blood-pancreatic juice barrier on 5-fluorouracil in post-pancreatoduodenectomy patients]

OBJECTIVE

To observe the distribution and the relationship of 5-Fu in the plasma and the pancreatic juice in post-pancreatoduodenectomy patients after 5-Fu given intravenously.

METHODS

After 5-Fu (1.0 g/m(2)) was given intravenously in post-pancreatoduodenectomy patients, blood and pancreatic juice were collected. The 5-Fu concentrations were determined by HPLC and at last the penetration ratio (PR) of 5-Fu was studied with PCNONLIN.

RESULTS

5-Fu in the plasma penetrated the pancreatic tissue and crossed the blood-pancreatic juice barrier (BPJB) in post-pancreatoduodenectomy patients (PR = 1.01 +/- 0.49). The concentration of 5-Fu in pancreatic juice was much higher than that in plasma.

CONCLUSIONS

5-Fu is suitable for adjuvant chemotherapy of pancreatic adenocarcinoma after pancreatoduodenectomy.

Metallothionein in radiation exposure: its induction and protective role

Since its discovery about 40 years ago, there has been a wide interdisciplinary research interest in metallothionein (MT) on its physiological and toxicological aspects. Functionally, MT is involved not only in metal detoxification and homeostasis, but also in scavenging free radicals during oxidative damage. Among over 4500 publications which can be retrieved by Medline search, only about 50 reports have been published on the relationship of MT with ionizing and UV radiation. In this review, we have evaluated critically the published data on the induced synthesis of MT by radiation, and the potential functions of MT in radiation induced cell damage. MT mRNA expression or MT synthesis was found to be induced by exposure of cells in vitro or tissues in vivo to ionizing or UV radiation. In most of the studies in animals and tissue cultures, high doses of ionizing radiation were used to induce MT, and, therefore, it is difficult to extrapolate these results to low level of repeated exposures to radiation in humans. Induced synthesis of MT is considered as one of the mechanisms involved in the adaptive response to low dose radiation exposure. The presence of MT in normal cells may provide protective effects from radiation-induced genotoxicity and cytotoxicity. However, in tumor cells, the presence of MT can result in drug and radiation resistance as well. These effects are modulated by other cellular factors, besides MT, such as antioxidants, and by the cell cycle stages in cell proliferation and differentiation.

Method for edge detection based on phase jump in a differential interferometer

We describe a new method for edge detection that uses polarization mixing in a differential heterodyne interferometer. When one of the focused beams of the interferometer scans across an edge, a phase jump of 180 degrees takes place in the very small region of the edge if certain conditions are satisfied. We call this phenomenon phase jump. The conditions in which phase jump can occur are given. The theoretical analysis shows that the slope of a phase jump is infinite and is not affected by step height, the vibration of the sample, or the intensity variation of the light source. Therefore phase jump can be used as the precise index for edge detection. The experimental results show good agreement with the theoretical analysis.

On-axis beam extinction through diffraction design and analysis

To optimize the functions of the surface-relief diffractive optical elements for optical limiters and other applications, we present a systematic design and analysis with numerical illustrations of the transmission properties of different surface-relief phase gratings and Fabry-Perot elements. The spectral response and the tolerance of fabrication errors have been included. An analysis shows that the blazed grating and the echelon grating, a multilevel element as a substitute of the blazed grating, can make the on-axis transmittance very low (less than 1% with one grating) over the broad visible band with a large tolerance of fabrication errors. The results are highly significant for the design of optical-limiting devices.

Metallothionein and apoptosis in primary human hepatocellular carcinoma (HCC) from northern China

BACKGROUND

Metallothionein (MT), acting as an antioxidant and zinc binding protein, may play an important role in regulation of apoptosis. Its differential expression has been documented in various human tumours.

MATERIALS AND METHODS

MT expression by immunohistochemical staining with a polyclonal antibody and apoptotic cells (APC) by TUNEL technique were investigated in 20 cases of hepatocellular carcinoma (HCC) and 2 normal livers from Northern China. Adjacent normal liver was available from 9 of these cases and 6 had adjacent cirrhotic tissue. There was no difference for MT staining and incidence of APC between normal liver and adjacent normal liver, and thus both were used as control liver.

RESULTS

Control liver had consistent MT staining with very low incidence of APC. Adjacent cirrhotic liver showed the same intensity of MT staining, with a similar incidence of APC to control liver. Twelve of 20 HCC cases (60%) showed no MT staining, and the rest also showed a low grade of MT staining as compared with control or adjacent cirrhotic livers. The incidence of APC in HCC was markedly higher than that in control liver or adjacent cirrhotic liver. The negative correlation of numbers of APC with MT expression was statistically significant (p < 0.005). The high incidence of APC in liver with a low MT expression was confirmed in double staining for MT and APC.

CONCLUSIONS

The present investigation from Northern Chinese samples has shown that MT expression in HCC was different from that in other human tumours, such as breast carcinoma. This suggests a different pattern of expression of MT protein in these two kinds of cancer. This investigation is important in understanding the mechanisms of the drug resistance of tumour cells, and may help to design better treatment strategies.