Evidence for selection of 11 amino acid CDR3 domains in V kappa III-derived immunoglobulin light chains in Kawasaki disease

Kawasaki disease (KD) is a rheumatic disease that occurs during childhood. Although T cells have been implicated as having an important role in the pathogenesis of KD, the role of B cells is unclear. To detect preferential expression of 11 amino acid complementarity determining region (CDR)3 domains, we used two-stage PCR (polymerase chain reaction) to analyze the CDR3 lengths of VkIII-derived immunoglobulin kappa light chains expressed in peripheral blood B cells during the acute, subacute, and convalescent phase of this disease. As controls, the peripheral blood B cells of age-matched normal and children with acute febrile diseases other than KD were tested. In 5 of 7 KD patients, expression of kappa light chains containing 11 amino acid codon CDR3 intervals was increased during the acute and subacute phase of KD but decreased during the convalescent phase. Two of the 7 KD patients showed the same pattern during the subacute and convalescent phase, but not during the acute phase. Two of the 5 patients with acute febrile diseases other than KD showed increased expression of kappa chains with 11 amino acid codon CDR3 intervals, but it was not a major fraction. Three of the 5 patients with acute febrile diseases other than KD and all normal control subjects showed only 9 and 10 amino acid CDR3 domains. These results strongly suggest that B cells expressing kappa light chains with the 11 amino acid CDR3 domains might be involved in the pathogenesis of KD.

Interaction between triiodothyronine and ovarian steroid hormones on the regulation of the release of thyrotropin and thyrotropin-releasing hormone in vitro

In vivo and in vitro experiments were designed to examine [1] the effect of triiodothyronine (T3) and/or ovarian steroids on the spontaneous and thyrotropin-releasing hormone (TRH)-stimulated release of thyrotropin (TSH) by the anterior pituitary gland (AP) in vitro; and [2] the in vivo effects of T3 and ovarian steroids on TRH-release in vitro. In the experiment 1, ovariectomized-thyroidectomized (Ovx-Tx) rats were injected with triiodothyronine (T3, 2 micrograms/kg), estradiol benzoate (EB, 25 micrograms/kg), progesterone (P, 10 mg/kg), T3 plus EB, T3 plus P, EB plus P, or T3 plus EB and P for 6 days before decapitation. The AP was incubated with Locke's medium, challenged with TRH (30 nM), recovered and then with T3 (10 nM) only or with T3+TRH, 30 min for each interval. Mediobasal hypothalami (MBHs) were challenged with high potassium (60 mM) for 30 min. In the experiment 2, the APs of Ovx-Tx rats were enzymatically dispersed and the AP cells were pretreated with or without EB (0-6 nM) for 72 h, and further with T3 (10 nM) for 24 h, followed by an incubation for 30 min with TRH (0-100 nM). The spontaneous and TRH-induced release of TSH in vitro from rat APs, and pituitary TSH content were increased by T3, or T3 plus P as compared with the animals injected with vehicle, or P alone. EB inhibits the effect of T3 on TSH release in vitro. Application of T3 in vitro prevented the release of TSH in response to TRH. EB dose-dependently relieved the inhibitory effect of T3 on TRH-induced TSH release in vitro. TRH release from MBH was increased by EB and inhibited by T3 or P. EB prevented the inhibitory effect of T3 on TRH release. P plus T3 potentiated the stimulatory effects of EB on TRH release. These results suggest that [1] the reduction of the concentration of plasma TSH by T3 is at least in part due to the inhibitory effects of T3 on TRH release from mediobasal hypothalamus, and TSH release in response to TRH, [2] the increased content and release of TSH from rat AP tissue by T3 via an in vivo effect may be involved in a short feedback loop of TSH on TRH release, and [3] ovarian steroid hormones play an inhibitory role in regulating T3 effects on the release of TSH and TRH.

Activation of caspase-3 protease via a Bcl-2-insensitive pathway during the process of ginsenoside Rh2-induced apoptosis

We have demonstrated that ginsenoside Rh2 (G-Rh2), a ginseng saponin with a dammarane skeleton, induces apoptosis of human hepatoma SK-HEP-1 cells as evidenced by analyses of DNA fragmentation, flow cytometry and changes in cell morphology. Ac-YVAD-CMK or Ac-DEVD-CHO effectively prevented G-Rh2-induced DNA fragmentation, indicating the involvement of caspase-like proteases in the process of apoptosis. In addition, G-Rh2 induced the processing of caspase-3 to an active form, p17. In stable Bcl-2 transfectants, G-Rh2 also induced DNA fragmentation, while staurosporine-induced DNA fragmentation was totally blocked. As it did in wild-type cells, G-Rh2 induced the proteolytic activation of caspase-3 protease and subsequent cleavage of PARP in the bcl-2 transfectants. In summary, G-Rh2 contains an apoptotic inducing activity in SK-HEP-1 cells which functions via Bcl-2-insensitive activation of caspase-3, followed by proteolytic cleavage of PARP.

[A study on male high school students' smoking patterns]

This study aims to investigate smoking patterns in high school student and to give student smoker effective information. The sample of 250 male high school students out of two different schools in Tae-Jŏn was questioned from July 10th to 15th, 1995. In analyzing these date, the statistics shows the realities by means of number of students. The results are summarized into 17 items as follows. Regarding the level of smoking, 140 students out of 250 admit that they have ever smoked, 52.1% of smoking students say that the motivation of beginning smoking is mainly curiosity. The survey shows that 22.9% of smoking students feel very good when smoking. It also shows that 30.0% of smoking students began smoking in the first grade of high school. With regard to the volume of smoking per day, 41.4% of smoking students smoke variably, 42.1% drink when smoking, 15.0% spend more than W 70,000 a month. About the question who knows the fact of their smoking, 51.5% answer that their friends know the fact of their smoking. In regard to the reslationship between smoking and school performance, 18.2% of non smoking students make poor grades as compared with 40% of smoking students, 9.3% of smoking students say that they are satisfied with the school life, but 35.7% of them are not satisfied. Regarding the attitude to smoking teachers, 35% of smoking students state that they are affected by them. 69.3% of smoking students say that they will stop smoking, while the remaining 30.7% say that they will keep smoking. The reason of 63.9% to stop smoking is that smoking is bad for the health. The reason of 46.5% to keep smoking is the acquired habit of smoking. 97.2% know the fact that the major element of cigarettes is nicotine and it is very harmful to the health. 40.8% recognize the harmful effect of smoking by TV and radio programs. 97.2% know that smoking could cause lung cancer. From the above results. I propose as follows We should make specific plan to keep smoking by simple curiosity from being developed into habitual smoking. We should teach them how harmful smoking is and make them stop smoking by themselves. It is very essential for family members and teachers to give continuous interest since childhood. As the teacher affect the students very much, they should give up smoking first. The incidence of smoking should be identified in each of the middle and high schools, smoking prohibition programs relevant to each school should be developed and implemented. The local community should ban cigarette vending machines. Cigarettes should not be sold to adolescents. By setting every place where adolescents gather including schools non-smoking area, we should decrease their impulse to smoke, then smoking opportunities, and harmful effects to them caused by passive smoking.

Neurofilaments are part of the high molecular weight complex containing neuronal cdc2-like kinase (nclk)

A cdc2-like kinase (nclk, comprised of cdk5 and its activator p25nck5a) that localizes primarily to neuronal cells has recently been identified. Although its precise physiological role remains unclear, a variety of nuclear and cytoplasmic proteins that may be targets for phosphorylation by this kinase have been suggested in various developmental and pathological states. Here we provide evidence for a functional association between nclk and neurofilament proteins: (i) brain neurofilament preparations include cdk5 and p25nck5a; (ii) nclk copurifies with neurofilament proteins using Mono-S and gel-filtration column chromatographic procedures; (iii) neurofilaments are coprecipitated with cdk5 kinase; and (iv) the addition of radiolabeled ATP to the immunoprecipitated complex results in phosphorylation of the cytoskeletal protein. These results are consistent with the formation of a functional macromolecular complex between nclk and neurofilaments in vivo and suggest a possible role for this kinase in regulating neuronal cytoskeletal networks.

Ginsenoside-Rg1, one of the major active molecules from Panax ginseng, is a functional ligand of glucocorticoid receptor

We have examined the possibility that a component of Panax ginseng, ginsenoside-Rg1 (G-Rg1), acts by binding to the glucocorticoid receptor (GR). G-Rg1 competed for [3H]dexamethasone (Dex) binding to GR with a specific affinity of 1-10 microM and activated a glucocorticoid responsive element-containing luciferase reporter gene. The dose-dependence patterns of G-Rg1 and Dex for these two effects were nearly identical, although two to three orders of magnitude higher concentration of G-Rg1 than that of Dex was required for the same magnitude of response. At the cellular level, the growth of FT02B cells was suppressed by G-Rg1 as well as by Dex, each of whose effects were abolished by RU486. These results demonstrate that G-Rg1 is a functional ligand of GR.

Evidence of genetic progression in human gastric carcinomas with microsatellite instability

Mutator phenotype tumors provide unique opportunities to unravel malignant progression because of various gene alterations acquired during clonal tumor evolution. Gastric carcinomas, which have been known to show frequent genetic instability, would be composed of initial gene alterations shared by most tumor areas and subsequent alterations restricted to particular tumor sites. To analyse the timing of genetic events, we examined separate sites of tumor tissue obtained from a given gastric carcinoma patient with microsatellite instability (MSI). Our study included 95 normal/tumor area pairs from 25 patients. Six of the 25 patients (24%) demonstrated various levels of MSI ranging from 7% (two of 30) to 97% (28 of 29) of markers tested in multiple tumor sites. Of the six patients, five manifested frameshift mutations in a tract of ten deoxyadenosines within transforming growth factor beta receptor type II and four demonstrated frameshift mutations in a tract of eight deoxyguanosines within BAX. These mutations were common to all tumor sites regardless of the various level of MSI phenotype, indicating initial events. Two of the six patients exhibited frameshift mutations in mononucleotide repeats of mismatch repair genes, hMSH3 and hMSH6, and the insulin-like growth factor II receptor in restricted tumor areas, indicating additional alterations. Insulin-like growth factor II receptor mutations appear to be caused by hMSH3 and hMSH6 mutations because the former mutations were confined to tumor portions with the latter two mismatch repair lesions. These results provide genetic progression evidence for gastric carcinomas of the mutator pathway. In this pathway, mismatch repair insufficiency initially targets mononucleotide tracts of transforming growth factor beta receptor type II and BAX. During tumorigenesis, primary mismatch repair failure may give rise to the secondary mismatch repair lesions, frameshift mutations of hMSH3 and hMSH6, which result in another tumorigenic mutation in the insulin-like growth factor II receptor.

Mechanism of gastric acid hypersecretion in patients with islet cell tumor without hypergastrinemia: studies in rats

BACKGROUND & AIMS

A nongastrin acid-stimulating peptide (NGASP) has been found in ulcerogenic pancreatic tumor syndrome without hypergastrinemia. The mechanism of gastric acid hypersecretion by NGASP was investigated in rats.

METHODS

In vivo, gastric acid secretion and in vitro histamine release from enterochromaffin-like (ECL) cells in responses to tumor extract (TE) and synthetic human gastrin-17 I or pentagastrin (PG) were studied. Whether the 2 secretagogues potentiate each other was determined.

RESULTS

TE dose-dependently stimulated histamine release, which was not blocked by a cholecystokinin (CCK)-B receptor antagonist. When TE was incubated with trypsin, the activity was abolished but was not affected by antibody. However, when rats were pretreated with antigastrin serum or CCK-B receptor antagonist, the acid secretion by TE was virtually abolished. The dose response of acid secretion to TE in the rats receiving PG in a threshold dose was significantly greater than that achieved by TE alone. Similarly, the dose response to PG combined with a threshold dose of TE was significantly greater than that produced by PG alone.

CONCLUSIONS

NGASP stimulates histamine release from ECL cells, but the release is not mediated via CCK-B/gastrin receptor. NGASP and gastrin may potentiate each other to produce acid hypersecretion in ulcerogenic pancreatic tumor syndrome.

Normal macrophage functions, but impaired induction of gamma delta T cells, at the site of bacterial infection in CD45 exon 6-deficient mice

We investigated the protective functions of macrophages and gamma delta T cells in adult CD45 exon 6-deficient (CD45 -/-) mice against an intraperitoneal (i.p.) infection with Listeria monocytogenes. gamma delta T cells are preferentially localized in the spleen, liver, and intraperitoneal cavity of the adult CD45-/- mice. Increased numbers of gamma delta T cells were observed after i.p. infection with L. monocytogenes in the peritoneal cavity of C57BL/6 (CD45 +/+) mice but not in CD45 -/- mice. The gamma delta T cells showed predominant usage of V delta 5 and V delta 6 rearranged to J delta 1 in the infected CD45 -/- mice which are the same as those used by resident gamma delta T cells of noninfected CD45 +/+ and CD45 -/- mice. Furthermore, we analyzed the protective abilities of the CD45 -/-, CD45 +/+, and gamma delta T cell-depleted mice at the early stage of the listerial infection. The numbers of bacteria in the spleens and livers of the CD45 -/- mice 5 days after the listerial infection were almost ten times larger than those in the CD45 -/- and gamma delta T cell-depleted CD45 +/+ mice. Macrophages showed normal antigen presentation, nitric oxide production and bactericidal activity for L. monocytogenes despite their lacking CD45 surface expression, suggesting that CD45-negative macrophages have a minimal influence on the increased bacterial multiplication in the CD45-/- mice. These results suggest that the gamma delta T cells are induced by the bacterial infection in a CD45-dependent manner, and that unresponsiveness of the gamma delta T cells results in only weak protection against L. monocytogenes in CD45 -/- mice.

Induction of cystine transport and other stress proteins by disulfiram: effects on glutathione levels in cultured cells

Disulfiram (Antabuse) (DSF) has been reported to protect rats and other animals from the effects of hyperbaric hyperoxia at 4 to 6 ATA (atmospheres). In contrast, DSF and diethyldithiocarbamate (DDC), its metabolite, accelerate the toxic effects in rats of 100% oxygen at 1 to 2 ATA. We have examined the effects of DSF and DDC on glutathione (GSH) levels in bovine pulmonary artery endothelial cells and Chinese hamster ovary cells. Increases in intracellular GSH occurred 8 to 24 h after addition of DSF to the culture media. These increases in intracellular GSH were associated with increases in the rate of uptake of cystine into the cells. DDC was a less effective inducer of cystine uptake and increased intracellular GSH levels than was DSF. At the concentrations used, neither DDC nor DSF caused significant decreases in intracellular superoxide dismutase levels. Exogenous sulfhydryl compounds including GSH and cysteine partially blocked the induction of cystine transport by DSF or DDC, suggesting that the induction might be mediated through a sulfhydryl reaction between DSF and some cellular components. The increases in GSH in the cultured cells were not significant by 4 h of exposure. In contrast, other stress proteins including heme oxygenase are induced by 2 to 4 h after DSF addition. In previously reported in vivo studies, DSF treatment protected against hyperbaric oxygen damage after as little as 1 to 4 h pre-exposure. This suggests that effects of DSF exposure other than GSH augmentation may be responsible for the protective effects seen in vivo.

Peptide-specific CTL induction in HBV-seropositive PBMC by stimulation with peptides in vitro: novel epitopes identified from chronic carriers

Cytotoxic T lymphocytes (CTL) recognize and destroy virus-infected cells, and it has been established that epitope-based peptides could induce such CTL in vivo as well as in vitro. In this study attempts were made to define the epitopes that are recognized by the CTL, and thus a series of 9- to 10-mer peptides derived from the amino acid sequences of hepatitis B virus (HBV) proteins were synthesized on the basis of the previously described HLA-A2 peptide binding motif. The binding assay of the synthetic peptides using transporter-associated with antigen processing (TAP)-deficient human cell line, T2, showed that eight out of 11 peptides tested enhanced the expression of HLA-A2 molecules on the T2 cell surface. Some of these peptides triggered activation of CTL in peripheral blood mononuclear cells of HBV-seropositive chronic carriers. The activated CTL in turn recognized and killed the T2 cells pulsed with the same peptides. This study shows that novel HLA-A2-restricted epitopes exist in the natural repertoire of immunity against HBV. These findings can be useful in developing peptide-based therapeutics against viral infections.

Effectiveness of low-dose ASA in prevention of secondary ischemic stroke, the ASA Study Group in Taiwan

This randomized double-blind controlled study was carried out to investigate the effect of 100 mg acetylsalicylic acid (ASA) per day on the secondary prevention of ischemic stroke. Patients who suffered a first ischemic stroke from 13 participating hospitals were enrolled. They were independent or only partially dependent in activities of daily living and all had received brain CT for diagnosis. Eligible patients were randomly allocated to the 100 mg ASA or the nicametate citrate (a vasodilator) groups, and trial medications were started within three to six weeks after the onset of stroke. The primary end point was cerebral reinfarction, and intracranial hemorrhage was classified as an adverse event. Four hundred and sixty-six patients participated in this study; and 222 cases (136 males and 86 females) were allocated to the ASA group while 244 cases (150 males and 94 females) were assigned to the nicametate group. No significant difference in baseline characteristics between the two groups was observed. Cerebral reinfarction developed 6.3% (14/222) in the ASA group and 11.9% (29/244) in the nicametate group. According to the Cox's proportional hazards model, the estimated risk ratio (ASA group vs. nicametate group) was 0.538, with a 95% confidence interval of 0.284-1.019. The result was of borderline statistical significance. The risk for cerebral reinfarction was reduced by almost 50% among those who took 100 mg ASA versus those who took nicametate.

Neuronal Cdc2-like kinases: neuron-specific forms of Cdk5

Neuronal Cdc2-like kinase, Nclk, is a heterodimer of a Cdk5 catalytic subunit and a 25 kDa regulatory subunit derived proteolytically from a neuron- and central nervous system-specific 35 kDa protein. The regulatory subunit is mandatory for kinase activity, hence it is designated the neuronal Cdk5 activator, p25/p35nck5a. Nclk has been suggested to play a regulatory role in neuro-cytoskeleton dynamics and in neuronal differentiation. In addition to the activation by Nck5a, Cdk5 is regulated by other mechanisms including additional activator proteins and inhibition by phosphorylation of specific amino acid residues. While Nclk shares common catalytic and regulatory properties with other members of the cdc2-like kinase family, it also displays unique characteristics that may be important for its neuronal functions.

Effect of cisapride and renzapride on gastrointestinal motility and plasma motilin concentration in dogs

The effects of cisapride and renzapride (BRL 24924), on plasma concentration of motilin and gastroduodenal motility were studied in seven dogs with implanted force transducers in the antrum and duodenum. In the interdigestive state, the i.v. administration of cisapride (5 mg) or renzapride (5 mg) administered in phase I resulted in a prompt and marked increase in plasma motilin concentration and in gastroduodenal motility. Mean plasma motilin levels during the first 30 min after cisapride and after renzapride injection were 85.0 +/- 6.5 (+/- S.E.) and 96.1 +/- 6.3 pM., respectively. These values were significantly greater (P < .001) than those for the corresponding time period of the control cycle, 52.2 +/- 5.6 and 57.4 +/- 5.3 pM (mean phase III level, 120 +/- 8.1 pM), respectively. The increases in the motilin level after cisapride or renzapride coincided with significant increases in contractile activities of the antrum to 43.2 +/- 5.3% and 44.9 +/- 4.6% and of the duodenum to 28.4 +/- 3.1% and 34.2 +/- 2.2% of phase III activity (100%) from that in the corresponding control period, 0.7 +/- 0.4% and 0.2 +/- 0.1%, respectively. The changes in both plasma motilin and motility in response to the two drugs were abolished completely by the i.v. administration of atropine. The drugs also enhanced the meal-induced contractile activities of the antrum as well as the duodenum but failed to influence the postprandial plasma motilin concentration. We conclude that cisapride and renzapride have similar effects on plasma motilin and gastroduodenal motility: 1) the two drugs increase plasma motilin levels and stimulate gastroduodenal motility in the interdigestive state, and 2) in the digestive state, both drugs enhance motility without influencing the plasma motilin levels.

Fluorescence, polarized fluorescence, and Brewster angle microscopy of palmitic acid and lung surfactant protein B monolayers

Fluorescence, polarized fluorescence, and Brewster angle microscopy reveal that human lung surfactant protein SP-B and its amino terminus (SP-B[1-25]) alter the phase behavior of palmitic acid monolayers by inhibiting the formation of condensed phases and creating a new fluid protein-rich phase. This fluid phase forms a network that separates condensed phase domains at coexistence and persists to high surface pressures. The network changes the monolayer collapse mechanism from heterogeneous nucleation/growth and fracturing processes to a more homogeneous process through isolating individual condensed phase domains. This results in higher surface pressures at collapse, and monolayers easier to respread on expansion, factors essential to the in vivo function of lung surfactant. The network is stabilized by a low-line tension between the coexisting phases, as confirmed by the observation of extended linear domains, or "stripe" phases, and a Gouy-Chapman analysis of protein-containing monolayers. Comparison of isotherm data and observed morphologies of monolayers containing SP-B(1-25) with those containing the full SP-B sequence show that the shortened peptide retains most of the native activity of the full-length protein, which may lead to cheaper and more effective synthetic replacement formulations.

The alteration of cytokeratin 18 molecule and its mRNA expression during tumor transformation in hepatoma

The cytokeratin 18 related molecules of human hepatocellular carcinoma have been previously recognized through a series of biochemical and immunological approaches. It is suggested that these molecules undergo modulation from human hepatocyte cytokeratin 18. To prove whether these molecules are produced by modulation or protein degradation, we checked the cytokeratin profile of human hepatoma cell line PLC/PRF/5 with the methods used before. These results revealed that the PLC cells have the same cytokeratin 18 related molecules as human hepatocellular carcinoma tissue. The gene expression of the cytokeratin 18 in non-tumor liver tissues, hepatocellular carcinoma and PLC/PRF/5 cells were investigated. First, the mRNAs of non-tumor liver tissues, hepatocellular carcinoma tissues and PLC/PRF/5 cells were collected by the acid guanidinium thiocyanate phenol chloroform method. After transcription into cDNA by reverse transcriptase polymerase chain reaction, the cDNAs of each specimen were amplified by PCR and then digested by SmaI and BamHI restriction enzymes. The digested cDNA fragments were electrophoresed in agarose gel and the base pairs were found to be the same in length between neoplastic and non-neoplastic hepatocytes.

Renal ischemia-reperfusion injury does not induce pulmonary dysfunction in sheep

It has already been shown that pulmonary injury is induced after intestinal or hind limb ischemia-reperfusion injury. The purpose of this study was to determine the effect of renal ischemia-reperfusion injury on the pulmonary system. We compared the pulmonary effects of 60 and 90 minutes ischemia followed by 24 hour reperfusion in sheep kidneys. Standard hemodynamic measurements, arterial and mixed venous blood gas analysis, urine output, creatinine clearance, and blood urea nitrogen concentration were measured at baseline, during ischemia and reperfusion periods. After 24 hours of reperfusion, animals were sacrificed and underwent autopsy with collection of samples for wet/dry lung-weight ratio, lung tissue conjugated dienes, and renal histology. As expected, renal ischemia resulted in an increased serum creatinine and blood urea nitrogen concentrations, decreased creatinine clearance, and histological evidence of renal damage. There was no evidence of pulmonary hypertension or hypoxemia during renal ischemia-reperfusion. There was also no significant difference in the wet/dry lung-weight ratios or lung tissue conjugated denies between the two ischemic groups (60 and 90 minutes) and nonischemic control group. These results suggest that renal ischemia-reperfusion injury was not associated with a significant degree of pulmonary dysfunction.

Ginsenoside-Rg5 suppresses cyclin E-dependent protein kinase activity via up-regulating p21Cip/WAF1 and down-regulating cyclin E in SK-HEP-1 cells

In the present study, we report that ginsenoside-Rg5 (G-Rg5), a newly discovered diol-containing ginsenoside, blocks the cell cycle of human hepatoma SK-HEP-1 cells via the down-regulation of cyclin E-dependent kinase activity. The results from flow cytometric analyses show that G-Rg5 arrests the cell cycle of SK-HEP-1 cells at the Gl/S transition phase. The cyclin E-dependent kinase activity that has been immunoprecipitated with cyclin E-specific antibody is down-regulated in response to G-Rg5. The results from immunoblottings show that the down-regulation of cyclin E-dependent kinase activity is related to increased protein levels of p21Cip/WAF1 and to decreased protein levels of cyclin E, CDK2, and CDC25A. Collectively, these data suggest that G-Rg5 blocks cell cycle of SK-HEP-1 cells at the Gl/S transition phase by down-regulating cyclin E-dependent kinase activity and that the down-regulation of cyclin E-dependent kinase activity is caused mainly by induced CDK2 inhibitor, p21Cip/WAF1 and decreased levels of cyclin E.

Neuronal Cdc2-like kinase (Nclk) binds and phosphorylates the retinoblastoma protein

The tumor suppressor retinoblastoma protein (RB) plays a central role in cellular growth regulation, differentiation, and apoptosis. Phosphorylation of RB results in a consequent loss of its ability to inhibit cell cycle progression. However, how RB phosphorylation might be regulated in apoptotic or postmitotic cells, such as neurons, remains unclear. Here we report that neuronal Cdc2-like kinase (Nclk), composed of Cdk5 and a neuronal Cdk5 activator (p25(nck5a)), can bind and phosphorylate RB. Since RB has been shown recently to associate with D-type G1 cyclins and viral oncoproteins through a common peptide sequence motif of LXCXE, Nclk binding may be mediated by a related sequence motif (LXCXXE) found in p25(nck5a). We demonstrate (i) in vitro binding of bacterially expressed p25(nck5a) to a GST-RB fusion protein, (ii) coprecipitation of GST-RB and reconstituted Cdk5.p25(nck5a), and (iii) phosphorylation of GST-RB by bacterially expressed Cdk5.p25(nck5a) kinase and by Cdk5.p25(nck5a) kinase purified from bovine brain. Finally, we show that immunoprecipitation of RB from embryonic mouse brain homogenate results in the coprecipitation of Cdk5 and that Cdk5 kinase activity is maximal during late embryonic development, a period when programmed cell death of developing neurons is greatest. Taken together, these results suggest that Nclk can bind to and phosphorylate RB in vitro and in vivo. We infer that Nclk may play an important role in regulating the activity of RB in the brain, including perhaps in apoptosing neurons.

Aloesin up-regulates cyclin E/CDK2 kinase activity via inducing the protein levels of cyclin E, CDK2, and CDC25A in SK-HEP-1 cells

In the present study, we show that aloesin, which is a low molecular weight ingredients present in Aloe vera, stimulates the proliferation of cultured human hepatoma SK-HEP-1 cells. The incorporation of [3H] thymidine into DNA in the cell cultures was significantly increased at a dose of 10 microM aloesin. The aloesin-induced DNA synthesis appears to require newly synthesized proteins because cycloheximide treatment blocked the DNA synthesis evoked by this compound. We then examined whether this compound increases the intracellular levels of cell cycle regulators by immunoblotting. The data showed that aloesin increased the levels of cyclin E, CDK2, and CDC25A in SK-HEP-1 cells. In addition, immuno-complex kinase assays showed that aloesin up-regulated the enzyme activity of cyclin E/CDK2 kinase in a dose-dependent manner. Collectively, these results suggest that aloesin stimulates the proliferation of SK-HEP-1 cells by inducing the intracellular levels of cyclin E/CDK2 kinase complex and CDC25A, which, together, result in the up-regulation of cyclin E-dependent kinase activity.

Simultaneous production of T helper-1-like cytokines and cytolytic activity by tumor-specific T cells in ovarian and breast cancer

Cytotoxic T-cell (CTL) cultures were generated from five ovarian cancer patients (OvCTL) and from three breast cancer patients (BrCTL). All CTL lines were T-cell receptor (TcR) alphabeta+ and predominantly CD8+ (73 +/- 13%). These CTL lines preferentially recognized autologous tumor cells in an HLA class I-restricted, and in part HLA-A2-restricted, manner. In addition, the CTL lines recognized allogeneic HLA-A2+ ovarian and breast tumor cells. Specific recognition was determined by T-cell-mediated cytotoxicity as well as cytokine release. Coculture of irradiated autologous tumor cells with OvCTL induced secretion of IFN-gamma, GM-CSF and TNF-alpha, but not IL-4, indicating a T helper-1-type response. Similar results were obtained when OvCTL and BrCTL were stimulated with histologically matched HLA-A2+ tumor cells. Also, BrCTL stimulated with HLA-A2+ but not HLA-A2- ovarian tumor cells produced significant levels of GM-CSF and TNF-alpha. Finally, the Her2/neu peptide p654-662, earlier identified as a tumor antigen in both ovarian and breast cancer, induced cytotoxicity as well as the specific release of IFN-gamma and TNF-alpha but not IL-4 by OvCTL and BrCTL. Thus, tumor-specific recognition by CTL was verified by cytotoxicity and cytokine release. The secretion of Th1-like cytokines as opposed to Th2-like cytokines suggest that therapeutically OvCTL and BrCTL could potentially enhance the endogenous immune response to tumor.

Enhanced anti-tumour effects of acriflavine in combination with guanosine in mice

The anti-tumour activity of acriflavine in combination with guanosine has been evaluated in solid or ascitic tumour-implanted animal models. Guanosine is known to potentiate the anti-tumour effects of some chemotherapeutic agents. Administration of acriflavine (15 mg kg-1 day-1, i.m., 14 days) to ICR mice subcutaneously implanted with Ehrlich carcinoma resulted in approximately 30% inhibition in tumour growth. In contrast, minor tumour growth inhibition was observed in animals treated with guanosine at the same daily dose. Treatment of animals with both acriflavine and guanosine (AG60, 1:1, w/w) at 30 mg kg-1 resulted in approximately 65% inhibition in tumour growth rate. Whereas treatment with acriflavine or guanosine resulted in 70% or 30% decrease in tumour weight, respectively, treatment of tumour-implanted mice with AG60 (30 mg kg-1) resulted in a 96% decrease in tumour weight, relative to control, 14 days after tumour-cell implantation. Dose-related inhibition in tumour growth rate was also observed in animals treated with AG60, with maximum (65%) inhibition noted at a dose of 30 mg kg-1 (ED50 23 mg kg-1). Suppression of body weight increase and elevated plasma glucose levels by acriflavine or AG60 indicated that glucose utilization might be impaired. The anti-tumour effect of AG60 was also determined in CDF1 mice intraperitoneally implanted with Ehrlich ascitic tumour. Ehrlich ascitic tumour proliferation was completely suppressed by AG60 (30 mg kg-1, i.p.). Microscopic analyses of intraperitoneal touch-prints revealed that AG60 was more effective in suppressing tumour proliferation than acriflavine alone. Fluorescent microscopic examinations demonstrated that acriflavine avidly bound with Yac-1 cell plasma membrane, leading to morphological changes in the cells, such as bleb formations, swelling and ballooning. The time-related changes in tumour cell morphology by acriflavine or AG60 might represent energy depletion, followed by osmotic lysis as a result of cationic influx. Enhanced anti-tumour activity of acriflavine in combination with guanosine might be explained by the blocking of nutrient transport through selective acriflavine binding with plasma membrane and by concomitant guanosine perturbation of cellular ATP production. This study demonstrates that guanosine enhances the anti-tumour effects of acriflavine against a variety of cancer cells without serious adverse effects, providing a preclinical basis for potential application of this combination against cancer proliferation.

Isolation and characterization of a gene encoding endo-beta-1,4-glucanase from pepper (Capsicum annuum L.)

The endo-beta-1,4-glucanases, or cellulases, of higher plants are cell wall-associated enzymes believed to function in cell wall changes associated with the diverse processes of fruit ripening, organ abscission and cell elongation. We have isolated and characterized cDNA and genomic clones encoding a cellulase, PCEL1, which is abundant in ripening pepper fruit. Genomic analysis indicates that PCEL1 is encoded by a single gene, PCEL1, which belongs to a small, structurally divergent gene family. In ripening fruit, PCEL1 transcription is initiated at two distinct sites which yields overlapping mRNA species of 1.7 and 2.1 kb. High-level accumulation of both transcripts occurs in red fruit, while the 1.7 kb transcript is detected at a much lower level in stem and petiolar tissue. The increase in cellulase activity which is measured during fruit ripening is the product of PCEL1 expression and is tightly coupled to fruit reddening. High-level applications of ethylene serve to enhance the rate of ripening and the accumulation of PCEL1 mRNA. A direct role for ethylene in regulating PCEL1 expression is shown by the exclusive induction, in immature green fruit, of the 1.7 kb transcript in response to prolonged high-level exposure to ethylene--a pattern of expression not observed in fruit development on the vine.

Comments on "Diagonal recurrent neural networks for dynamic systems control". Reproof of theorems 2 and 4 [and reply]

In their original paper, C.-C. Ku and K.Y. Lee (ibid., vol.6, p.144-56, 1995) designed a diagonal recurrent neural network architecture for control systems. Liang asserts that a condition assumed in the proof of its convergence does not necessarily apply, and presents alternative theorems and proofs. Lee replies that Liang has misunderstood the original paper, and also that he made mistakes in his new proofs, but acknowledges that the original paper did not go into full detail about how a limitation would be implemented. Lee also presents a revision for the case of time-varying weights.

A new algorithm for Kohonen layer learning with application to power system stability analysis

In certain classification problems, input patterns are not distributed in a clustering manner but distributed uniformly in an input space and there exist certain critical hyperplanes called decision boundaries. Since learning vector quantization (LVQ) classifies an input vector based on the nearest neighbor, the codebook vectors away from the decision boundaries are redundant. This paper presents an alternative algorithm called boundary search algorithm (BSA) for the purpose of solving this redundancy problem. The BSA finds a fixed number of codebook vectors near decision boundaries by selecting appropriate training vectors. It is found to be more efficient compared with LVQ and its validity is demonstrated with satisfaction in the transient stability analysis of a power system.