Thrombin causes pseudopod detachment via a pathway involving cytosolic phospholipase A2 and 12/15-lipoxygenase products

Thrombin causes rapid pseudopod detachment and shortening in Dunning rat prostatic carcinoma (MAT-Lu) cells. As seen by interference reflection microscopy and by immunofluorescence analysis with antibodies to paxillin and talin, the primary event is disassembly of adhesion sites. Biochemically, thrombin is a potent activator of cytosolic phospholipase A2 and increases eicosanoid production in these cells. The pseudopod effects are blocked by lipoxygenase (but not cyclooxygenase) inhibitors. Arachidonic acid and 12(S)-hydroxyeicosatetraenoic acid or 15(S)-hydroxyeicosatetraenoic acid mimic the thrombin effect. We conclude that in certain cancer cells, thrombin is a pseudopod repellent that exerts its effect via a cascade involving cytosolic phospholipase A2, 12/15-lipoxygenase, and 12(S)- and/or 15(S)-hydroxyeicosatetraenoic acid.

[An experimental study on treatment of limbal alkali burn by allograft transplantation with cultured stem cells on amniotic membrane]

OBJECTIVE

To study the treatment of rabbit limbal alkali burn by cultured limbal stem cells growing on amniotic membrane for allograft transplantation.

METHODS

After the primary culture of the rabbit corneal stem cells, they were cultured on amniotic membrane in DMEM/HamF12 medium for one week. Corneal stem cells and amniotic membrane were transplanted on the limbal and scleral area of the rabbit model with alkali burn. The corneal changes were observed by a slitlamp everyday, and the corneal pathological changes were examined.

RESULTS

Cultured rabbit corneal stem cells continued to proliferate, differentiate and form multiple cell layers on amniotic membrane. After transplantation with cultured stem cells and amniotic membrane, the rabbit epithelium showed corneal phenotype and progressive decrease of vascularity and stromal infiltration in the limbal and peripheral zone. Pathological examination verified that the limbal and peripheral corneal epithelium was composed of multilayer cells, the neo-vascularization was reduced and stromal inflammatory cells were decreased.

CONCLUSIONS

Allograft transplantation with cultured limbal stem cells can restore corneal epithelial cell composition, decrease neovascularization, maintain limbal cellular barrier function and provide better condition for keratoplasty later.

A negatively charged region of the skeletal muscle ryanodine receptor is involved in Ca(2+)-dependent regulation of the Ca(2+) release channel

The ryanodine receptor/Ca(2+) release channels from skeletal (RyR1) and cardiac (RyR2) muscle cells exhibit different inactivation profiles by cytosolic Ca(2+). D3 is one of the divergent regions between RyR1 (amino acids (aa) 1872-1923) and RyR2 (aa 1852-1890) and may contain putative binding site(s) for Ca(2+)-dependent inactivation of RyR. To test this possibility, we have deleted the D3 region from RyR1 (DeltaD3-RyR1), residues 1038-3355 from RyR2 (Delta(1038-3355)-RyR2) and inserted the skeletal D3 into Delta(1038-3355)-RyR2 to generate sD3-RyR2. The channels formed by DeltaD3-RyR1 and Delta(1038-3355)-RyR2 are resistant to inactivation by mM [Ca(2+)], whereas the chimeric sD3-RyR2 channel exhibits significant inactivation at mM [Ca(2+)]. The DeltaD3-RyR1 channel retains its sensitivity to activation by caffeine, but is resistant to inactivation by Mg(2+). The data suggest that the skeletal D3 region is involved in the Ca(2+)-dependent regulation of the RyR1 channel.

A phase I study of paclitaxel, etoposide, and cisplatin in extensive stage small cell lung cancer

This Phase I study was designed to determine the maximally tolerated dose (MTD) of paclitaxel with standard doses of cisplatin and etoposide for patients with untreated extensive stage small cell lung cancer (SCLC). Secondary objectives were to determine the toxicities, response rate, response duration, and overall survival in this cohort. Twenty-eight SCLC patients were enrolled into four dose levels. All patients received a fixed dose of cisplatin at 80 mg/m2, i.v., day 1. The first group received etoposide 50 mg/m2, i.v. day 1 and 100 mg/m2 p.o., days 2-3, whereas all subsequent groups received etoposide 80 mg/m2, i.v., day 1 and 160 mg/m2, p.o., days 2-3. The paclitaxel starting dose was 135 mg/m2, i.v., over a 3-h period and was escalated to 175 and 200 mg/m2. Cycles were repeated every 21 days for a maximum of six cycles. Granulocyte-colony stimulating factor was not given prophylactically but was allowed in subsequent cycles according to the American Society of Clinical Oncologists guidelines. All 28 SCLC patients were evaluable for toxicity, and 23 patients were evaluable for response. Myelosuppression was the major toxicity, with grade 4 neutropenia occurring in 23 of 28 patients (82%), but febrile neutropenia was uncommon and developed in 4 patients (14%). Grade 4 thrombocytopenia and anemia were rare, occurring as isolated events in one patient each. Dose-limiting peripheral neuropathy was observed at a paclitaxel dose of 200 mg/m2. Grade 4 nausea/vomiting and diarrhea were also noted at this dose level. Five patients had complete responses (22%), and 14 patients had partial responses (61%). The overall response rate was 83% with a median time to progression of 7.5 months, a median survival of 10 months, and a 1-year survival rate of 39%. This three-drug combination of paclitaxel with cisplatin and etoposide is active with acceptable toxicity. Neurotoxicity was dose limiting at 200 mg/m2 of paclitaxel. Neutropenia was frequent but not associated with significant morbidity. The recommended doses for future clinical trials are 175 mg/m2 paclitaxel, i.v., over a 3-h period on day 1 with 80 mg/m2 cisplatin, i.v., on day 1 and 80 mg/m2 etoposide, i.v., on day 1 and 160 mg/m2 p.o. on days 2 and 3 with growth factor support. The Southwestern Oncology Group has instituted a Phase II study with this dose schedule.

Functional complementation of the Schizosaccharomyces pombe wis1 mutant by Arabidopsis MEK1 and non-catalytic enhancement by CTR1

Arabidopsis thaliana MEK1 encodes a MAPKK homolog whose role in plants is currently unknown. High (but not low) expression of MEK1 rescued the Deltawis1 (MAPKK) mutant of the Schizosaccharomyces pombe Win1/Wis4-Wis1-Sty1 stress-activated MAPK pathway. Rescue was dependent upon upstream and downstream components of the pathway, suggesting that MEK1 might function in a homologous MAPK pathway in plants. When MEK1 was expressed at a low level, rescue of Deltawis1 was achieved by co-expressing Arabidopsis CTR1 (a putative MAPKK kinase (MAPKKK)). CTR1 constructs alone did not rescue the pathway, indicating that CTR1 augmented MEK1 function. Further data indicated that this enhancement was not due to CTR1 kinase activity.

AML1 (CBFalpha2) cooperates with B cell-specific activating protein (BSAP/PAX5) in activation of the B cell-specific BLK gene promoter

AML1 plays a critical role during hematopoiesis and chromosomal translocations involving AML1 are commonly associated with different forms of leukemia, including pre-B acute lymphoblastic leukemia. To understand the function of AML1 during B cell differentiation, we analyzed regulatory regions of B cell-specific genes for potential AML1-binding sites and have identified a putative AML1-binding site in the promoter of the B cell-specific tyrosine kinase gene, blk. Gel mobility shift assays and transient transfection assays demonstrate that AML1 binds specifically to this site in the blk promoter and this binding site is important for blk promoter activity. Furthermore, in vitro binding analysis revealed that the AML1 runt DNA-binding domain physically interacts with the paired DNA-binding domain of BSAP, a B cell-specific transcription factor. BSAP has been shown previously to be important for B cell-specific regulation of the blk gene. Physical interaction of AML1 with BSAP correlates with functional cooperativity in transfection studies where AML1 and BSAP synergistically activate blk promoter transcription by more than 50-fold. These results demonstrate physical and functional interactions between AML1 and BSAP and suggest that AML1 is an important factor for regulating a critical B cell-specific gene, blk.

CCAAT/enhancer-binding protein activates the CD14 promoter and mediates transforming growth factor beta signaling in monocyte development

Transcription factors from the CCAAT/enhancer-binding protein (C/EBP) family play important roles in myeloid cell differentiation. CD14 is a monocyte/macrophage differentiation marker and is strongly up-regulated during monocytic cell differentiation. Here, we report the direct binding of C/EBP to the monocyte-specific promoter of CD14. Transactivation analyses demonstrate that C/EBP family members significantly activate the CD14 promoter. These data indicate that C/EBP is directly involved in the regulation of CD14 gene expression. When myelomonoblastic U937 cells are treated with vitamin D(3) and TGF-beta, they differentiate toward monocytic cells. Using specific antibodies against different C/EBP family members in electrophoretic mobility shift assays and Western blot assays, we have identified a specific increase in the DNA binding and the expression of C/EBPalpha and C/EBPbeta during U937 monocytic cell differentiation, and we found C/EBPalpha and C/EBPbeta bind to the promoter in heterodimer. Furthermore, with stably transfected cell lines, we demonstrate that the C/EBP binding site in the CD14 promoter plays a critical role for mediating TGF-beta signaling in the synergistic activation of CD14 expression by vitamin D(3) and TGF-beta during U937 differentiation. This may indicate that C/EBPs have important functions in the process of TGF-beta signal transduction during monocyte differentiation.

Distribution and prevalence of hyperpolarization-activated cation channel (HCN) mRNA expression in cardiac tissues

HCN cation channel mRNA expression was determined in the rabbit heart and neonatal and adult rat ventricle using RNase protection assays. In the rabbit SA node, the dominant HCN transcript is HCN4, representing >81% of the total HCN message. HCN1 is also expressed, representing >18% of the total HCN mRNA. Rabbit Purkinje fibers contained almost equal amounts of HCN1 and HCN4 transcripts with low levels of HCN2, whereas rabbit ventricle contained predominantly HCN2. The SA node contained 25 times the total HCN message of Purkinje fibers and 140 times the total HCN message of ventricle. No reports of hyperpolarization-activated current (If) exist in rabbit Purkinje fibers, and we could not record If in rabbit ventricular myocytes. To investigate the possible role of isoform switching in determining the voltage dependence of If, we determined the prevalence of HCN isoforms in neonatal and adult rat ventricle. We had previously determined the threshold for activation of If to be approximately -70 mV in neonatal rat ventricle and -113 mV in adult rat ventricle. In both neonatal and adult rat ventricle, only HCN2 and HCN4 transcripts are present. The ratio of HCN2 to HCN4 is approximately 5:1 in the neonate and 13:1 in the adult. Taken together, these results suggest that different cardiac regions express different isoforms of the HCN family. The HCN1 and HCN4 isoforms are most closely associated with a depolarized threshold for If activation, whereas the HCN2 isoform is associated with a more negative activation curve.

The effect of one injection of Depo-Provera on the human vaginal epithelium and cervical ectopy

Two studies in rhesus monkeys have shown that progesterone implants, Depo-Provera and Norplant, were associated with vaginal thinning. Progesterone implants have also been associated with an increased risk of simian immunodeficiency virus (SIV) acquisition. This study in 16 women was done to assess vaginal epithelial thickness and number of cell layers from biopsies taken in the untreated follicular and luteal phases, and at 1 month and 3 months after administration of Depo-Provera. There was no significant change over time in either parameter from biopsies obtained in the luteal phase compared with those at either time after Depo-Provera administration. There was also no change in the mean number of Langerhans cells in vaginal wall specimens and no change in cervical ectopy. It appears that women do not respond to exogenous progestins with the dramatic vaginal thinning seen in rhesus monkeys.

Analysis of redox regulation of cytochrome c-induced apoptosis in a cell-free system

In this study, we investigated the importance of redox and Bcl-2 status on cytochrome c-mediated apoptosis. Two mouse lymphoma cell lines, LYas and LYar that express Bcl-2 protein at different levels, were used to reconstitute a cell-free system. Cytoplasmic extracts made from apoptosis-sensitive LYas cells 2.5 h after exposure to 5 Gy gamma-radiation were able to induce apoptosis in isolated nuclei, whereas extracts made from LYas cells at time points earlier than 2. 5 h, or from Bcl-2-overexpressing, apoptosis-resistant LYar cells at all time points after irradiation were inactive. Apoptotic activity was restored to inactive extracts by the addition of oxidized but not reduced cytochrome c. Cytochrome c reductase was able to inhibit apoptosis in extracts made from LYas cells 2.5 h after irradiation and LYar extracts activated by addition of oxidized cytochrome c. Antioxidants, but not oxidant defensive enzymes, blocked apoptosis implying that antioxidants might alter the redox state of factors important in mediating apoptosis. These findings confirm the importance of cellular redox state during apoptosis and are consistent with a role for Bcl-2 in regulating this redox state.

Sample size determination for multiple comparison studies treating confidence interval width as random

Methods for optimal sample size determination are developed using four popular multiple comparison procedures (Scheffe's, Bonferroni's, Tukey's and Dunnett's procedures), where random samples of the same size n are to be selected from k (>/=2) normal populations with common variance sigma2, and where primary interest concerns inferences about a family of L linear contrasts among the k population means. For a simultaneous coverage probability of (1-alpha), the optimal sample size is defined to be the smallest integer value n*m such that, simultaneously for all L confidence intervals, the width of the lth confidence interval will be no greater than tolerance 2deltal (l=1,2,...,L) with tolerance probability at least (1-gamma), treating the pooled sample variance S2p as a random variable. Using Scheffe's procedure as an illustration, comparisons are made to usual sample size methods that incorrectly ignore the stochastic nature of S2p. The latter approach can lead to serious underestimation of required sample sizes and hence to unacceptably low values of the actually tolerance probability (1-gamma'). Our approach guarantees a lower bound of [1-(alpha+gamma)] for the probability that the L confidence intervals will both cover the parametric functions of interest and also be sufficiently narrow. Recommendations are provided regarding the choices among the four multiple comparison procedures for sample size determination and inference-making.

[A preliminary comparision of the abilities of factor analysis and wavelet analysis in reducing noise of absorption spectra]

In this paper, the abilities of factor analysis and wavelet analysis for reducing noise of the absorption spectra are compared. Also, the different joint ways of these two techniques are used to reduce the noise of the same spectra. Some preliminary results are obtained.

Electronic transmission properties in a mesoscopic necklace with inhomogeneous magnetic flux

The electronic transmission properties and the energy spectrum of a mesoscopic necklace with inhomogeneous flux is calculated. We found interesting transmission behavior that is quite different from the case with homogenous flux. In this model, the transmission depends on both the modulation mode and the amplitude of the flux. The electronic transmission properties can be explained from the energy spectrum of the system.

[Studies on data compression of 1-D NMR spectra using wavelet transform]

The multiresolution signal decomposition (MRSD) algorithm based on wavelet transform was applied to the compression of 1-D NMR spectra. A NMR spectrum which was composed of 32768 data points was investigated and the spectrum can be completely reconstructed with the residual square deviation (RSD) being as small as 2.7769 x 10(-4) when the spectrum was compressed to 512 data points. The relationship among the RSD and the different wavelet function, number of decomposiion and the compression ratio was also discussed.

[Cervical lymph node metastasis and recurrence in supraglottic carcinoma after operation]

OBJECTIVE

To evaluate the regional control efficacy of elective neck dissection (END) in patients with supraglottic carcinoma.

METHODS

The incidence of cervical recurrences of 582 patients with supraglottic carcinoma treated in this hospital from 1981 to 1993 were retrospectively reviewed.

RESULTS

Three hundred and ninety-two cases (67.35%) of this group had T3 and T4 primary lesions. Among them, 147 cases (37.50%) had positive nodes(N+) and this accounted for 86.47% (147/170) of all N+ patients. Ipsilateral or bilateral cervical recurrence occurred in 33 of 126 (26.19%) node negative (N0) cases who had not had neck dissection and 30 of them (90.90%) were among T3 and T4 groups. However, Contralateral lymph node recurrence occurred only in 40 of 286(13.99%) N0 cases who had had END and 30 of them (75%) were among T3 and T4 groups. There were 163 cases who were readmitted and received surgery again for different purposes. The three and five year survival rates in the second stage END group were 86.67% and 77.78%, in metastasis group 64.81% and 32.50%, in recurrent group 33.33% and 30.77% respectively. There were significant differences in survival rates among these groups.

CONCLUSION

Patients underwent elective neck dissection achieved better survival than those on "wait and watch" policy and salvage surgery. Elective neck dissection is recommended for the treatment of supraglottic carcinoma, especially for the T3 and T4 diseases.

Metabolism of methyl tert-butyl ether and other gasoline ethers in mouse liver microsomes lacking cytochrome P450 2E1

To reduce the production of pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE) and other ethers such as ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Metabolism of these gasoline ethers is catalyzed by cytochrome P450 (P450) enzymes. P450 2E1, which metabolizes diethyl ether, was suggested to be an enzyme involved. The present study used 2E1 knock-out mice (2E1-/-) to assess the contribution of 2E1 to the metabolism of MTBE, ETBE and TAME. Liver microsomes prepared from the 2E1 knock-out mice lacked 2E1 activity (assayed as N-nitrosodimethylamine demethylation), but were still active in metabolizing all three gasoline ethers. The levels of ether-metabolizing activity (nmol/min per mg) in the liver microsomes from 7 week old female 2E1 knock-out mice were 0.54+/-0.17 for MTBE, 0.51+/-0.24 for ETBE and 1.14+/-0.25 for TAME at a 1 mM substrate concentration. These activity levels were not significantly different from those of the sex- and age-matched C57BL/6N and 129/Sv mice, which are the parental lineage strains of the 2E1 knock-out mice and are both 2E1+/+. Our results clearly demonstrate that 2E1 plays a negligible role in the metabolism of MTBE, ETBE and TAME in mouse livers.

[Genetic polymorphism and susceptibility to occupational chronic manganism: a case-control study]

OBJECTIVE

In a case-control study, the possible genetic factors relevance to occupational chronic manganism were investigated.

METHODS

Forty-nine manganisms who were welders and ferromanganese smelters occupationally exposed to manganese dust and fume from three metallurgical industries, and fifty unrelated healthy control subjects who were working same workshops were recruited. The subjects were matched for sex, age, cigarette and alcohol intake. The manganese exposure duration was also matched in this case-control study. Genetic polymorphism of cytochrome P450 2D6L (CYP2D6L) gene and NAD(P)H: quinone oxidreductase (NQO1) genes from all subjects were investigated. The mutations of CYP2D6L gene located exon 6 were analyzed by a polymerase chain reaction (PCR)-based DNA amplification combined with Hha I restriction fragment length polymorphism (RFLP). The substitution of 609(C-T) at exon 6 of DT-diaphroase gene was analyzed by PCR combined Hinf I RFLP.

RESULTS

The frequency of polymorphic allels, a mutation of CYP2D6, was significantly lower in patients with manganism (16.3%) than that of the controls (29.0%). A significant association was also found between the homozygote variant of CYP2D6L gene and occupational manganism. These results suggest that the CYP2D6 gene might be one of the susceptibility genes for Mn-induced neurotoxicity. The allele and genotype frequencies of NQO1 gene were similar in the manganism cases and control subjects.

CONCLUSION

It is possible that CYP2D6 gene may be a valuable susceptibility biomarker responded to Mn-induced central nervous system disorders in workers exposed to manganese.

[Relationship between the expression of transforming growth factor beta type I receptor (T beta R I) and prognosis of hepatocellular carcinoma (HCC)]

OBJECTIVE

To study the expression of T beta R I in HCC tissues and its clinical significance.

METHODS

Expressions of T beta R I in HCC tissues (HT, n = 30) and surrounding liver tissues(HST, n = 30) as well as four normal control liver tissues (CIT, n = 4) were determined by radioligand binding assay with 125I TGF beta 1 as the ligand. Relationships between some clinicopathological parameters of HCC and the relative expression rates of T beta R I in HCC were studied.

RESULTS

Compared with that in HST, the expression of T beta R I HT was significantly lower than in HST and CIT (P < 0.01). The expression of T beta R I in HST is similar to that in CIT. T beta R I relative expression rates in the group of no capsule or capsule invaded and in the group of tumor embolus were markedly decreased (P < 0.05). No close relationships were found between the T beta R I relative expression rate and age, sex, HBV infection, liver cirrhosis, AFP concentration, tumor diameter, tumor number, tumor differentiation as well as tumor embolus.

CONCLUSIONS

The low expression of T beta R I in HT may be one of the key event which promote the HCC malignant growth by protecting them against the growth inhibition effect of active TGF beta. The T beta R I relative expression rate may be related to the prognosis of HCC.

Identification of individuals at high risk for head and neck carcinogenesis using chromosome aneuploidy detected by fluorescence in situ hybridization

To visualize the accumulation of chromosome abnormalities in head and neck squamous cell carcinomas (HNSCC) and investigate the extension of the abnormal field, we applied the fluorescence in situ hybridization (FISH) technique to tumor cells and cells collected from a large extension of clinically normal buccal mucosa distant from the tumor in 10 patients. DNA probes specific for 14 human chromosomes (1, 2, 3, 6, 7, 8, 9, 10, 11, 12, 15, 17, X, and Y) were used in dual-target, dual-color FISH assays. Control specimens were collected from oral mucosa of 10 healthy non-smokers, in order to define the tolerance limits for abnormalities, and from 10 healthy smokers. Extensive aneuploidy was detected in most of tumor specimens, more frequently represented by chromosome gains than losses. Interestingly, the clinically normal distant oral regions displayed chromosomal aneuploidies in seven out of the 10 patients tested. These findings support the occurrence of field cancerization in HNSCC. In addition, interphase FISH is demonstrated as an effective technique for detecting chromosome aneuploidy associated with malignancy and a potential tool for non-invasive screening of individuals at high-risk for HNSCC.

[Long-term follow-up result of partial laryngectomy in senile patients with laryngeal carcinoma]

OBJECTIVE

To study the long-term follow-up result of laryngectomy with reservation of laryngeal function in senile patients.

METHODS

Ninety-nine patients who were above 65 years old and underwent partial laryngectomies from 1986 to 1990 were summarized. Among them, 14 cases underwent vocal cord resection, 31 vertical hemilaryngectomy, 15 horizontal supraglottic hemilaryngectomy, 2 horizontal glottic laryngectomy, 22 horizontovertical (3/4) laryngectomy, 5 subtotal laryngectomy, 10 total laryngectomy with cricopharyngeal anastomosis.

RESULTS

All patients had their phonation and respiration restored. Decannulation rate was 91.9%. No death occurred during the operation. No severe postoperative complications were found. 3.5-year survival rates were 76.7% and 75.5% respectively.

CONCLUSION

Senility is not a contraindication for laryngectomy with reservation of laryngeal function. The key points are that surgeons should master indications correctly and improve surgical skill to decrease postoperative complications.

[A study on proliferation and differentiation of limbal stem cells]

OBJECTIVE

To study the proliferation and differentiation of limbal stem cells (LCs) in vitro and examine the effects of epithelial growth factor (EGF) on cell proliferation.

METHODS

The cells were cultured in DMEM/F12 medium. The proliferation and differentiation of cultured cells were studied by colony-forming efficiency (CFE), immunohistochemistry staining and Western blot examination.

RESULTS

LCs could be passaged 5 times in this culture condition. The CFE of stem cells was (5.07 +/- 2.35)%, while that of the central epithelial cells (CCs) was (1.12 +/- 0.86)%. The rates of freezing and recovery were (0.43 +/- 0.22)% in LCs and (0.16 +/- 0.07)% in CCs. Limbal stem cells could be stimulated to proliferate better by EGF at the concentration of 5 and 20 ng/ml. The staining of keratin 3 (K3) to stem cells in the primary culture was negative, but positive in the second and third passages. However, the expression of K3 by Western blot examination was positive in the primary and second passages but negative in the fourth one.

CONCLUSION

It is better for limbal stem cells to be used for transplantation and drug screening in the primary culture.

KCNQ2 and KCNQ3 potassium channel subunits: molecular correlates of the M-channel

The M-current regulates the subthreshold electrical excitability of many neurons, determining their firing properties and responsiveness to synaptic input. To date, however, the genes that encode subunits of this important channel have not been identified. The biophysical properties, sensitivity to pharmacological blockade, and expression pattern of the KCNQ2 and KCNQ3 potassium channels were determined. It is concluded that both these subunits contribute to the native M-current.