DNA polymerase delta is involved in the cellular response to UV damage in human cells

We have used antibodies specific for either polymerase delta (pol delta) or its accessory protein, proliferating cell nuclear antigen (PCNA), to demonstrate that they can markedly inhibit the capacity of HeLa nuclear extracts to effect repair of UV-damaged plasmid DNA. This provides the first unambiguous evidence for the involvement of pol delta in DNA repair synthesis. The mRNA levels of both pol delta and PCNA were significantly stimulated subsequent to UV irradiation of cultured cells, providing the first evidence that the cellular response to UV damage may involve regulation of pol delta and PCNA at the gene level. Thus, DNA polymerase delta and its accessory proteins, in addition to their function in replicative DNA synthesis, also function in DNA repair synthesis.

Identification of yeast component A: reconstitution of the geranylgeranyltransferase that modifies Ypt1p and Sec4p

Members of a large family of small GTP-binding proteins, termed Rabs in mammalian cells or Ypt and Sec4 in yeast, regulate vesicular traffic in all eukaryotic cells. These proteins are able to bind to membranes because they are modified by the type II geranylgeranyltransferase (GGTase-II), a multisubunit complex. Component A, encoded by the choroideremia gene in humans, is an escort protein that brings Rabs to component B, the catalytic alpha/beta heterodimer. Mutations in the catalytic subunits of the yeast GGTase-II (Bet2p/Mad2p) disrupt the membrane attachment of Ypt1p and Sec4p and this in turn blocks membrane traffic. In mammalian cells, deletions in choroideremia lead only to retinal degeneration, even though GGTase-II activity is defective. The yeast MRS6 gene encodes a protein that is approximately 30% identical to the choroideremia gene product. Here we show that the addition of recombinant Mrs6p to bacterially expressed Bet2p (beta subunit) and Mad2p (alpha subunit) reconstitutes GGTase-II activity in vitro, demonstrating that Mrs6p is yeast component A. Like Bet2p and Mad2p, Mrs6p is required for the membrane attachment of Ypt1p and Sec4p in vivo. In contrast to what has been observed before for the loss of function of the choroideremia gene, the depletion of Mrs6p from yeast cells blocks vesicular transport. Thus, these findings suggest that there is one essential escort protein in yeast, while more than one may exist in mammalian cells.

Selective inability of LPS-activated B lymphocytes to produce antibodies against autologous and allogeneic MHC class I antigens

Lipopolysaccharide (LPS)-activated B lymphocytes have been found to produce autoantibodies of a variety of specificities. We found that LPS-induced autoantibodies did not include antibodies against self H-2 class I antigens, suggesting a selective tolerance induction against some, but not other, autoantigens. However, LPS-activated B lymphocytes not only failed to produce antibodies against autologous H-2 class I antigens, but also against allogeneic H-2 class I antigens, suggesting a selective regulation of B cells to synthesize antibodies directed against autologous and allogeneic major histocompatibility complex antigens.

[Establishment of a human pancreatic adenocarcinoma cell line(JF305) with p53 expression]

A human pancreatic cancer cell line(JF305) was established from a pancreatic adenocarcinoma xenograft in nude mice. These cells have passed 103 passages in more than 1 year. The plating efficiency was 30.6%, and doubling time was 49.5 hours. Chromosomal analysis showed a human karyotype with a chromosome number between 66-130. JF305 cells exhibited epithelial morphologic features resembling the structure of the original tumor, and they grew to born tumor when inoculated again into nude mice. With immunohistochemical staining, the nuclei of JF305 cells were positive for p53. Therefore, JF305 offer a good model for the study of human pancreatic adenocarcinoma and P53 gene mutation.

Mabiosides C-E: triterpenoid saponins from the bark of Colubrina elliptica

Three novel saponins, mabiosides C-E, were isolated from the bark of Colubrina elliptica together with the known mabioside B and [alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)-alpha-L- arabinopyranosyl]-(1-->3)-jujubogenin. All the structures were established by spectroscopic methods.

Optoacoustic trace-gas monitoring with near-infrared diode lasers

An inexpensive resonant optoacoustic monitoring system using near-infrared laser diodes was developed. It was demonstrated that wavelength modulation at the resonance frequency of the cell provides a superior signal-to-noise ratio compared with amplitude modulation and eliminates background drifts and fluctuations. The system was tested out on ammonia. Its sensitivity is 8 parts in 10(9) (S/N = 1) at atmospheric pressure, which corresponds to a minimum detectable absorption coefficient of approximately 3.5 × 10(-11) cm(-1) W(-1). The pressure dependence of the optoacoustic resonance was also investigated. The monitor can be used as a continuous flow-through system up to a flow rate of approximately 3.5 L/min.

RNA polymerase binding using a strongly acidic hydrophobic-repeat region of sigma 54

sigma 54 is a rare bacterial protein that substitutes for sigma 70 in the case of Escherichia coli genes transcribed by certain activators with enhancer protein-like properties. It contains a strongly acidic region of previously unknown function. Gel mobility-shift assays using sigma 54 deletion mutants show that this region is essential for sigma 54 to bind the core RNA polymerase and recruit it to the promoter. Multiple-point mutational analysis shows that the acidic amino acids and overlapping periodic hydrophobic amino acids are necessary for this binding. Related sequences are not found within the core binding determinant of sigma 70, which binds the same core RNA polymerase. This comparison suggests that the core RNA polymerase interacts differently with the two sigma factors, likely contributing to the critical differences in transcription mechanism in the two cases.

Genetic study of indirect inguinal hernia

We performed a genetic analysis of 280 families with congenital indirect inguinal hernia ascertained in Shandong province. The multifactorial threshold model and segregation analysis were applied to these families to investigate the mode of inheritance of congenital indirect inguinal hernia. Our results indicate that congenital indirect inguinal hernia is not compatible with a multifactorial threshold model, and the frequent vertical transmission and high segregation ratio suggest autosomal dominant inheritance with incomplete penetrance and sex influence. Through further pedigree analysis of the multiple case families with at least two closely related affected members, we noted preferential paternal transmission of the disease gene, which might suggest the role of genomic imprinting in the aetiology of this condition.

[Treatment of the lesions at anterolateral area of the brain stem via far-lateral approaches]

Based on our 12 cases of lesions located at anterolateral area of brain stem which were successful operated upon via far-lateral approaches, the study and progress of the far-lateral approaches were reviewed. In our cases, there were 4 intramedullary lesions including 3 vascular malformations, and 1 glioma. The other 8 lesions were located at extramedullary anterolateral area of brain stem including 2 large acoustic neuromas, 2 meningiomas at clivus and 2 neurofibromas at anterolateral areas of the medulla oblongata and upper spinal cord, 1 teratoma at the anterolateral area of pone-medulla and 1 large aneurysm at the junction of vertebrobasilar artery. During the operations, 8 lesions were totally removed. 1 meningioma was subtotally removed. 2 (1 vascular malformation and 1 glioma) were subtotally removed too, the aneurysm was only given a decompression of increased intracranial pressure, because the patient's interrupted respiration during the operation. There were nooperative mortality and morbidity and good results were obtained in this group. The details of our modified far-lateral approach was also described in this paper.

Triterpenoid saponins from the root of Sideroxylon cubense

Two triterpenoid saponins were isolated from the root of Sideroxylon cubense and their structures were established as 3-O-beta-D-glucopyranosyl-28-O-[alpha-L-rhamnopyranosyl(1-->3)- beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2) beta-D-xylopyranosyl] protobassic acid and 3-O-beta-D-glucopyranosyl protobassic acid. The first, designed as sideroxyloside A, is a new natural product.

[Single channel analysis on calcium channel blockade action of panaxadiol and panaxatriol saponins on cultured rat ventricular myocytes]

Wistar rat ventricular myocytes were isolated. Panaxadiol saponins 1500 micrograms.ml-1, panaxatriol saponins 300 micrograms.ml-1, verapamil 37.5 micrograms.ml-1, or BAY k 8644 5 mumol.L-1 were added into the bath solution separately. The single channel activities of L, T, and B type calcium channels were recorded before and after the administration, using voltage patch-clamp technique in cell-attached configuration. The calcium channel blockade effect of these 2 groups of ginsenosides was authenticated verified. The mechanism existed in the decrease in both the open time and the open-state probability of the calcium channel.

Defective transcriptional activation by diverse VP16 mutants associated with a common inability to form open promoter complexes

Three different types of VP16 mutants were assayed in vitro. These included deletion of the C-terminal activation subdomain and alterations in either the acidic or non-acidic components of the minimal activation domain. The mutant GAL4-VP16 proteins were found to be transcriptionally defective using a HeLa cell nuclear extract. In all three cases the loss of transcription activity was accompanied by a commensurate loss in ability to form open transcription complexes. The comparison implies that the diverse components of GAL4-VP16 activate transcription by the common facilitation of steps required for open complex formation. The results further imply that open complex formation may be a common target for mammalian transcriptional activation, as known previously to be the case in bacterial systems.

[Effects of the combination of Astragalus membranaceus (Fisch.) Bge. (AM), Angelica sinensis (Oliv.) Diels (TAS), Cyperus rotundus L. (CR), Ligusticum chuangxiong Hort (LC) and Peaonìa veitchii lynch (PV) on the hemorheological changes in "blood stagnating" rats]

The "blood stagnating" rat model was built with adrenaline and cold stimulation. Its hemorrheological character was an increase in the viscosity, thickness and liability to coagulate. The experimental result showed that AM and TAS could decrease the whole blood specific viscosity, but at the same time increase the plasma specific viscosity. The qi-regulating drug CR and two blood-activating drugs LC and PV could improve the hemorrheological changes in "blood stagnating" rats. The combination of qi-regulating drugs and blood-activating drugs had more favorable effect.

[The observation of therapy of anemia in chronic renal failure with recombinant human erythropoietin]

Anemia is one of the serious complications of chronic renal failure, therapy with recombinant human erythropoietin (r-HuEPO) can correct such anemia officiently. For most patients, the initial dose of r-HuEPO is 100U/kg, by intravenously or subcutaneous, three times a week. After 6 weeks of treatment, Hb could increase to 100g/L, and Hct to above 0.33-0.35. Then 500/kg 3 time a week can be used as maintaining dose. 4 patients need maintaining dose of 150U/kg, for pulmonary infection, poor nutrition, and poor iron supply. Therefore, during the treatment, iron folie acid and Vit B12 should be applied sufficiently and treat the infection effectively with the increasing of Hb and Hct, 2/3 of the patients have hypertension which can be controlled with medication. If there is thrombosis in the dialyzer, the dose of heparin should be increased. The patients on r-HuEPO should be dialysised sufficiently to prevent hyperkalemia.

[The immunohistochemical study of p53 protein in primary lung cancer]

The expression of tumour suppressor gene P53 products-P53 protein in patients with primary lung cancer has been studied by ABC immunohistochemical method using McAb 1801 as probe. Abnormalities in P53 expression were found in 63 of 78 carcinomas, 23 of 26 squamous cell carcinomas, 23 of 29 adenocarcinomas, 7 of 11 large cell carcinomas, 7 of 9 small cell carcinomas and all 3 cases of adenoid cystic carcinomas showing abnormal P53 expression, whereas no expression of P53 was detectable in 11 normal lung samples. These findings suggest that the pathogenesis of lung cancer may also be related with abnormalities of P53 gene.

Transcriptional and posttranscriptional regulation of the expression of the erythropoietin receptor gene in human erythropoietin-responsive cell lines

With erythroid differentiation, committed progenitor cells acquire the ability to respond to erythropoietin (Epo). Epo interacts with target cells through the Epo receptor (Epo-R), whose expression is tightly regulated in a lineage-specific fashion. Epo-R expression is presumed to be progressively activated or repressed as cells progress along the erythroid or the myeloid pathway, respectively. Little is known of the mechanisms that underlie the erythroid-specific expression of the Epo-R gene. GATA-1, the major known transcription factor involved in Epo-R gene regulation, is not erythroid-specific. We have studied the regulation of the expression of the Epo-R gene in two related human Epo-responsive cell lines, UT-7 and UT-7 Epo. These lines express Epo-R at high levels because of amplification of the endogenous gene, which is apparently not rearranged. Treatment for 6 to 24 hours with the tumor promoter, phorbol myristate acetate (PMA), or 24 hours of growth factor starvation (Epo or granulocyte/macrophage colony-stimulating factor [GM-CSF]) decreased or increased the levels of Epo-R mRNA, respectively. In the case of growth factor starvation, the increase (approximately equal to threefold) in the level of Epo-R mRNA correlated directly with an increase in the rate of Epo-R gene transcription as measured by run-off assay. Both increases were observed as early as 3 hours after the growth factor was withdrawn and were reversible; levels of mRNA and transcription rates returned to baseline 3 hours after the cells were reexposed to growth factors. The changes in Epo-R expression after growth factor starvation were coordinated with changes in the level of expression of GATA-1 that were detected both at the mRNA and at the gene transcription level under these conditions (suggesting that GATA-1 was responsible for this upregulation). During PMA treatment, after a transient increase in Epo-R mRNA at 1 hour, a progressive decline in the level of Epo-R mRNA was observed; the level of Epo-R mRNA decreased by 50%, and fell below the level of detection by 6 and 24 hours, respectively. This decrement was explained in part by a fourfold reduction in the rate of gene transcription as well as a reduction (measured as levels of Epo-R mRNA in the presence of actinomycin D) in mRNA stability. The changes in transcription rate occurred in the absence of changes in the level of GATA-1 binding activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Computer assisted analysis of leukocyte rheological behavior in microvasculature

A new approach called Time-Space Scheme has been recommended for measuring the velocity of moving blood cells in the microvasculature. In each sampling time, the data are put into a row, then rows are integrated in sequential times as sequential rows. The motion of various objects in the field of microcirculation can be analyzed from the time-space image. In the time-space image RBC's flow appears as a diagonal dark stripe and WBC's flow as a bright stripe. The slope at different points on those stripes reflects the local velocity of RBCs and WBCs. Using the time-space image analyzing method, the velocities of erythrocyte and leukocyte in microcirculation are measured simultaneously by a self-designed interactive image processing system. According to characteristic of leukocyte flowing movement, leukocytes in microvasculature are divided into the three kinds: central axial-flowing leukocyte, rolling leukocyte and adhesive leukocyte. On this basis, we introduce the leukocyte-endothelium contact time as a quantitative index for leukocyte-endothelium interaction. During hemorrhagic shock, the phenomenon of leukocyte-endothelium adhesion has been observed by this system, which suggests that the method is effective and useful for the research of microcirculation.

Bet2p and Mad2p are components of a prenyltransferase that adds geranylgeranyl onto Ypt1p and Sec4p

Three different prenyltransferases have been identified in yeast and higher cells, the farnesyltransferase and the type I and type II geranylgeranyltransferases (GGTase). The farnesyltransferase and GGTase-I modify peptides in vitro with the CAAX (C, Cys; A, aliphatic residue; X, terminal amino acid) consensus motif. These enzymes are heterodimers that have different beta-subunits and a shared alpha-subunit. In yeast, the RAM2 gene encodes this alpha-subunit. RAM2 is also homologous to MAD2, a yeast gene whose product has been implicated in the feedback control of mitosis. We have shown that Bet2p is a component of the yeast GGTase-II (refs 6, 12) that geranylgeranylates Ypt1p, a small GTP-binding protein that mediates transport from the endoplasmic reticulum to the Golgi complex. Here we report that Mad2p is a component of this enzyme. Bet2p forms a complex with Mad2p that appears to bind geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. The efficient transfer of geranylgeranyl onto small GTP-binding proteins requires the presence of an additional activity.

Bolus contaminant dispersion in oscillatory tube flow with conductive walls

Dispersion of a bolus contaminant in a straight tube with oscillatory flows and conductive walls is solved by using a derivative-expansion method. Using asymptotic methods when small conductance exists, the axial dispersion, as measured by the time-averaged effective diffusivity, increases over the insulated case, as long as the dimensionless frequency (Womersley parameter), alpha, is smaller than a critical value. When alpha exceeds this value, axial dispersion is diminished by wall conductance. The functional dependence of this critical alpha on the system parameters is investigated. We examine the radial wall transport both for total mass and localized flux, which is found to be independent of velocity field, and compute the time-dependent total mass of wall transport and asymptotic Sherwood number for large times as a function of the wall conductance.

[Influence of 11 ginsenoside monomers on action potentials of myocardiocytes]

Eleven ginsenoside monomers were added to cultured myocardiocytes of neonatal Wistar rats in a concentration of 20 micrograms.ml-1. And the action potentials (AP) were led with microelectrodes. Rb1, Rb2, Rb3, Rc, Rg1, Rg2, Re, and Rh1 inhibited AP, decreasing APA by 20%, 13%, 5%, 18%, 30%, 37%, 28%, and 23%, respectively. The potency of the most effective monomer Rg2 20 micrograms.ml-1 was similar to that of the calcium channel blocker nimodipine 1.25 micrograms.ml-1. Rd, Rf, and Ro had no significant influence on AP. The average potency of the panaxatriol saponin (PTS) monomers were greater than that of the panaxadiol saponin (PDS) monomers. The above demonstrate the reason why the calcium channel blockade action of PTS is stronger than that of PDS results from the summation of monomer drug effects.