Angiotensin II type 2 receptor stimulation of neuronal delayed-rectifier potassium current involves phospholipase A2 and arachidonic acid

Angiotensin II (Ang II) elicits an Ang II type 2 (AT2) receptor-mediated increase in delayed-rectifier K+ current (IK) in neurons cultured from newborn rat hypothalamus and brainstem. This effect involves a pertussis toxin (PTX)-sensitive Gi protein and is abolished by inhibition of serine and threonine phosphatase 2A (PP-2A). Here, we determined that Ang II stimulates [3H]arachidonic acid (AA) release from cultured neurons via AT2 receptors. This effect of Ang II was blocked by inhibition of phospholipase A2 (PLA2) and by PTX. Because AA and its metabolites are powerful modulators of neuronal K+ currents, we investigated the involvement of PLA2 and AA in the AT2 receptor-mediated stimulation of IK by Ang II. Single-cell reverse transcriptase (RT)-PCR analyses revealed the presence of PLA2 mRNA in neurons that responded to Ang II with an increase in IK. The stimulation of neuronal IK by Ang II was attenuated by selective inhibitors of PLA2 and was mimicked by application of AA to neurons. Inhibition of lipoxygenase (LO) enzymes significantly reduced both Ang II- and AA-stimulated IK, and the 12-LO metabolite of AA 12S-hydroxyeicosatetraenoic acid (12S-HETE) stimulated IK. These data indicate the involvement of a PLA2, AA, and LO metabolite intracellular pathway in the AT2 receptor-mediated stimulation of neuronal IK by Ang II. Furthermore, the demonstration that inhibition of PP-2A abolished the stimulatory effects of Ang II, AA, and 12S-HETE on neuronal IK but did not alter Ang II-stimulated [3H]-AA release suggests that PP-2A is a distal event in this pathway.

[Determination of copper, zinc, iron and calcium in wheat and maize and three nitrogen compounds in high and low risk areas of esophageal cancer]

This study reports the concentrations of copper, zinc, iron and calcium in wheat and maize from high risk area Linzhou and low risk area Yuzhou of esophageal cancer and three nitrogen compounds of four types of drinking water in Linzhou. The results showed that the concentrations of zinc and calcium in wheat and maize from Linzhou were significantly lower than these from Yuzhou, the copper concentrations in grains were higher and the iron in maize was lower. The nitrate-N concentrations in four types of drinking water from Linzhou were below the national standard but the nitrite and NH3-N concentrations were higher than the national limits. The results suggest that the low concentrations of zinc, iron and calcium and high concentrations of copper in grains as well as the high concentrations of nitrite and NH3-N may be related to the etiology of esophageal cancer.

The diagnosis of diffuse goitre by ultrasound imaging in children

In order to find an easy and accurate procedure for diagnosis of diffuse goitre in children, we examined 50 patients with diffuse goitre using fine needle aspiration biopsy cytology, thyroid antibody detection, thyroid hormone analysis and ultrasound imaging. In the meantime, 109 healthy children (control) were examined by ultrasound imaging. The results showed that thyroid imaging in health children was a smooth echo pattern with stronger homogenous echogram than surrounding muscle tissues. The patients with diffuse goitre showed an abnormally enlarged thyroid volume. In 22 (84.6%) of 26 children with chronic lymphocytic thyroiditis, a varied patch hypoechogenicity was found, of whom 18 (81.8%) had positive results of antibody testing. On the contrary, echo-pattern was normal in 17 (70.8%) of 24 patients with diffuse thyroid proliferation and only the remainder (7/24, 29.1%) had abnormal echo-pattern as well as elevated auto-antibody titers, of whom 2 were confirmed as chronic lymphocytic thyroiditis by a repeat fine needle aspiration biopsy 1 year later. By using combined ultrasound imaging and antibody determination, 92% of the cases with chronic lymphocytic thyroiditis could be diagnosed. Our study suggests that ultrasonic imaging is an easy, non-invasive, reproducible and effective procedure in the differential diagnosis of chronic lymphocytic thyroiditis in children.

Experimental study on the treatment of diabetes by phloridzin in rats

Male rats at six weeks of age were divided into 5 groups at random: in group I, the rats with diabetes received 70% pancreatectomy; group II had sham-operation serving as controls; diabetic rats in group III were treated with phloridzin; In group IV rats received sham-operation and phloridzin treatment and group V were phloridzin-treated diabetic rats to be studied after discontinuance of phloridzin. 70 days after surgery, the weights and insulin contents of operated remnant pancreas were markedly higher than the expected value of 30%, reaching 44% (48.2% +/- 15.2%), demonstrating that the remnant pancreas still had capacities of compensatory regeneration and proliferation capacities. Phloridzin-treated diabetic rats completely returned to normal in terms of oral glucose tolerance and insulin sensitivity. Discontinuation of phloridzin treatment in diabetic rats resulted in the recurrence of insulin resistance. These results suggested that normalization of hyperglycemia could ameliorate insulin resistance under diabetic conditions.

[Light microscopic observation of bone interface of titanium-coated 317L plate screw]

The observational results of bone interface of titanium-coated 317L plate screw and 317L plate screw under light microscope are reported in the present paper. Osseointegration was formed in both kinds of screws after implanting. In the titanium-coated 317L plate screw group, the inflammatory reaction was slighter, the new bone formed earlier in the interface and the bone was combined with the metal tightly, whereas in the uncoated 317L plate screw group, the relationship between the bone and metal was only a state of contact. These indicate that the bone interface and tissue compatibility of titanium-coated 317L plate screw may be better than that of the 317L plate screw.

Phenotypic stability of a cytotoxic T-cell line directed against an immunodominant epitope of human carcinoembryonic antigen

CTL lines have now been generated against defined peptides of a range of human tumor-associated antigens (TAAs). One of the potential uses of these epitope-specific CTLs is in adoptive transfer immunotherapy. This is a modality, however, that will require long-term in vitro culture of CTLs. To date, little has been reported concerning the phenotypic stability of human epitope-specific CTLs as a consequence of long-term in vitro propagation via peptide stimulation. We report here the serial phenotypic characterization of a CTL line directed against an immunodominant epitope (YLSGANLNL, designated CAP-1) of human carcinoembryonic antigen (CEA). This CTL line was derived from peripheral blood mononuclear cells of a patient with metastatic carcinoma who had been treated with a recombinant CEA-vaccinia vaccine in a Phase I trial; the CTLs were analyzed through 20 in vitro cycle passages of stimulation with CAP-1 peptide and interleukin 2 in the presence of autologous antigen-presenting cells. The CTL line was shown to be phenotypically stable in terms of high levels of cytokine (IFN-gamma, tumor necrosis factor, and granulocyte-macrophage colony-stimulating factor) production, expression of homing-adhesion molecules, ability to lyse peptide-pulsed targets, and ability to lyse human carcinoma cells endogenously expressing CEA in a MHC-restricted manner. Vbeta T-cell receptor gene usage was also analyzed. These studies thus present a rationale for the use of long-term cultured epitope-specific human CTLs, directed against a human TAA for potential adoptive transfer immunotherapy protocols.

Impaired beta-cell function and deposition of fat droplets in the pancreas as a consequence of hypertriglyceridemia in OLETF rat, a model of spontaneous NIDDM

Hypertriglyceridemia is known to be a feature of obesity-related NIDDM, but the patho-etiological significance of this association is obscure. The effects of triglycerides (TGs) on beta-cell function and morphological changes in pancreas were examined using in vivo and in vitro approaches in male OLETF rats at ages 6, 12, and 30 weeks, with their diabetes-resistant counterpart, LETO rats, as normal controls. The results showed that, in the fasting state, plasma TGs in OLETF rats were increased 2.5-fold at age 6 weeks, 3.3-fold at age 12 weeks, and 6.2-fold at age 30 weeks, compared with age-matched LETO rats. The TG content in islets from 12-week-old OLETF rats was significantly increased when compared with those from their age-matched counterparts, but this was not the case with the 6-week-old OLETF rats. Therefore, the islets from 6-week-old rats were cultured with either free fatty acids (FFAs; 1.0 mmol/l sodium oleate) or TG (5.0 mmol/l Intralipide) for 72 h. Several abnormalities in OLETF rats were evident, in contrast to the results from control LETO rats: 1) glucose-induced insulin secretion was more inhibited by either FFAs or TGs in the presence of 27.7 mmol/l glucose, a result associated, at least in part, with reduced glucokinase activity in the islets; 2) a marked elevation in TG content was found in the islets; and 3) the deposition of fat droplets in the enlarged islets, even in the beta-cells, was found by Oil Red O-insulin double staining at age 30 weeks. In conclusion, hypertriglyceridemia resulted in significant TG stores in the islets, which subsequently inhibited glucose-induced insulin secretion, at least in part, via reduced glucokinase activity in the islets. Fat droplets in islets, therefore, may play an important role in hastening the development of NIDDM in this rat model.

[Effects of green tea on growth inhibition and immune regulation of Lewis lung cancer in mice]

C57/BL6J mice were inoculated with Lewis lung cancer cells as an experimental model to study the effects of green tea on cancer prevention, inhibition of tumor growth and immune regulation in mice with tumor. Results showed that weight of thymus in C57/BL6J mice and its index declined, proportion of positive CD4 subgroup of T lymphocyte and ratio of CD4+, to CD8+ reduced, baseline chemilumi-nescence decreased in peripheral white blood cells, yeast zymosan stimulated chemiluminescence increased, and number of immunoglobulin M formation cells decreased. It indicated that green tea had obvious inhibition in Lewis lung cancer and protective effects, to various extent, on adverse changes of above indices.

Capillary isoelectric focusing

Capillary isoelectric focusing (CIEF) provides excellent resolution of proteins with the advantage that separations are carried out in a capillary format with on-tube detection and automated analysis. Recent advances in the technique provide improved resolution, reproducibility and reliability. This review summarizes improvements in sample preparation, capillary selection, and focusing and zone mobilization procedures which have helped CIEF become a more robust analytical method. New applications are reviewed, in particular the use of CIEF in analysis of biopharmaceutical products.

Identification of an enhancer agonist cytotoxic T lymphocyte peptide from human carcinoembryonic antigen

A vaccination strategy designed to enhance the immunogenicity of self-antigens that are overexpressed in tumor cells is to identify and slightly modify immunodominant epitopes that elicit T-cell responses. The resultant T cells, however, must maintain their ability to recognize the native configuration of the peptide-MHC interaction on the tumor cell target. We used a strategy to enhance the immunogenicity of a human CTL epitope directed against a human self-antigen, which involved the modification of individual amino acid residues predicted to interact with the T-cell receptor; this strategy, moreover, required no prior knowledge of these actual specific interactions. Single amino acid substitutions were introduced to the CAP1 peptide (YLSGANLNL), an immunogenic HLA-A2+-binding peptide derived from human carcinoembryonic antigen (CEA). In this study, four amino acid residues that were predicted to potentially interact with the T-cell receptor of CAP1-specific CTLs were systematically replaced. Analogues were tested for binding to HLA-A2 and for recognition by an established CTL line directed against CAP1. This line was obtained from peripheral blood mononuclear cells from an HLA-A2+ individual vaccinated with a vaccinia-CEA recombinant. An analogue peptide was identified that was capable of sensitizing CAP1-specific CTLs 10(2)-10(3) times more efficiently than the native CAP1 peptide. This enhanced recognition was shown not to be due to better binding to HLA-A2. Therefore, the analogue CAP1-6D (YLSGADLNL, Asn at position 6 replaced by Asp) meets the criteria of a CTL enhancer agonist peptide. Both the CAP1-6D and the native CAP1 peptide were compared for the ability to generate specific CTL lines in vitro from unimmunized apparently healthy HLA-A2+ donors. Whereas CAP1 failed to generate CTLs from normal peripheral blood mononuclear cells, the agonist peptide was able to generate CD8+ CTL lines that recognized both the agonist and the native CAP1 sequence. Most importantly, these CTLs were capable of lysing human tumor cells endogenously expressing CEA. The use of enhancer agonist CTL peptides may thus represent a new efficient direction for immunotherapy protocols.

The potentiating actions of cigarette smoking on ethanol-induced gastric mucosal damage in rats

BACKGROUND & AIMS

Cigarette smoking has been associated with peptic ulceration. However, the ulcerogenic mechanisms are still undefined. The aim of this study was to investigate the effects and possible mechanisms of cigarette smoke on ethanol- or cold-restraint stress-induced gastric damage.

METHODS

Rats were exposed to cigarette smoke followed by either an ethanol (70%) challenge or cold-restraint stress. The severity of mucosal damage, levels of prostaglandin E2 and leukotriene C4, determined by radioimmunoassay, and neutrophil infiltration in the stomach were assessed.

RESULTS

Smoke dose-dependently potentiated ethanol-but not stress-induced ulcer. It reduced mucosal prostaglandin E2 and increased myeloperoxidase activity. Filtered cigarette smoke did not have these effects. The acidic fraction from the filters produced similar potentiating effects and also delayed ulcer healing. Mucosal leukotriene C4 and serum nicotine levels did not correlate with the mucosal injury in the stomach. Neutropenia abolished the ulcerogenic action and the increase of myeloperoxidase activity produced by both cigarette smoke and acidic fraction.

CONCLUSIONS

Reduction of prostaglandin E2 and increase in neutrophil accumulation in the gastric mucosa are responsible for the potentiating action of acute smoke exposure on ethanol-induced gastric damage. Substances other than nicotine could contribute to these adverse reactions in the stomach.

Modulation of K+ and Ca2+ currents in cultured neurons by an angiotensin II type 1a receptor peptide

Angiotensin II (ANG II) inhibits delayed rectifier K+ current (IK) and stimulates total Ca2+ current (ICa) in neurons cocultured from newborn rat hypothalamus and brain stem, effects mediated via ANG II type 1 (AT1) receptors. Here, we identify potential G protein activator regions of the AT1 receptor responsible for initiating the intracellular changes that lead to alterations in these currents. Intracellular application into cultured neurons of a peptide corresponding to the third cytoplasmic loop of the AT1 receptor (AT1a/i3) mimicked the actions of ANG II on IK and ICa, whereas application of a peptide corresponding to the second cytoplasmic loop (AT1a/i2) did not alter these currents. This modulation of IK and ICa by AT1a/i3 involves intracellular messengers (G alpha q, protein kinase C, and intracellular Ca2+) that are identical to those involved in the modulation of IK and ICa following ANG II activation of AT1 receptors. These data provide functional evidence for a role of the third cytoplasmic loop of the AT1 receptor in G protein coupling and subsequent modulation of ion channel effectors.

[Study on dietary pattern and nutrients intakes of residents in areas of high and low incidence of esophageal cancer]

The dietary pattern and nutrients intakes of residents in areas with high and low prevalence of esophageal cancer were studied by 3 days' dietary survey. The results showed that the dietary pattern and nutrients intakes of residents in areas with low prevalence (ALP) of esophageal cancer was superior to that in area with high prevalence (AHP). The amount of soybean, meat and vegetable consumed by residents in the ALP was more than that in the AHP. Deep color vegetable and gaelic vegetable were dominant in ALP, but so were light color vegetables in AHP. The protein quality and quantity as well as the amount of Zn, Ca, RE and riboflavin consumed in the AHP were lower than that in the ALP. The energy from carbohydrate accounts for 78.14% of the total in the AHP. It is suggested that poor dietary pattern and the quality and amount of nutrients intake may be related to the development of esophageal cancer, and nutrition intervention in area of high prevalence seems rational.

[An investigation on the epidemiology of injuries in middle school students]

In November 1996, we made an investigation among 1194 students from 25 of grade 2 classes at 4 middle schools in our city. The result shows that a total of 13 different kinds of injuries happened to the students, with a rate of 81.66%. Among which, 7 kinds of injuries took the first 7 places: injuries from falls (39.78%), knife-cutting (37.68%), throat injuries by sharp bone blocks (36.09%), traffic accidents (18.17%), bumping to sharp materials (17.08%), burns (17.08%) and by sharp-weapon hurt (16.83%). We also made an investigation on the causes and characteristics and related factors of injuries. Thus some preventive measures were preliminarily put out.

Intracellular inhibition of HIV-1 replication using a dual protein- and RNA-based strategy

Exporting unspliced human immunodeficiency virus type 1 (HIV-1) RNA from the nucleus to the cytoplasm, through an interaction between the viral regulatory Rev protein and Rev response element (RRE) RNA, is a critical step in the HIV-1 life-cycle. Disruption of either Rev or the RRE will completely inhibit HIV-1 replication. As such, a strategy for somatic gene therapy to treat HIV-1 infection by intracellular expression of an anti-HIV-1 Rev single chain variable fragment (SFv) and a ribozyme which specifically targets the RRE was developed. The anti-Rev D8SFv, which specifically targets the Rev activation domain, may be a key component of combination intracellular immunization, as it has been previously shown to potently inhibit Rev function, thereby inhibiting viral replication. In the present studies, different HIV-1 RRE region-specific hammerhead ribozymes were constructed and their anti-HIV-1 replication effects were assayed in diverse RNA polymerase (pol) II and III promoters and vector systems in cell culture. Utilizing this combination of an SFv and a ribozyme as a dual strategy to block HIV-1 replication, both at the protein and RNA level, data from these studies demonstrated that potent inhibition of HIV-1 replication can be achieved via this approach. Combination gene therapies hold promise, analogous to combination chemotherapeutic regimens, for the in vivo treatment of HIV-1 infections.

D-glucose stimulates mesangial cell GLUT1 expression and basal and IGF-I-sensitive glucose uptake in rat mesangial cells: implications for diabetic nephropathy

The complications of diabetes arise in part from abnormally high cellular glucose uptake and metabolism. To determine whether altered glucose transporter expression may be involved in the pathogenesis of diabetic nephropathy, we investigated the effects of elevated extracellular glucose concentrations on facilitative glucose transporter (GLUT) expression in rat mesangial cells. GLUT1 was the only transporter isoform detected. Cells exposed to 20 mmol/l glucose medium for 3 days demonstrated increases in GLUT1 mRNA (134%, P < 0.002), GLUT1 protein (68%, P < 0.02), and V(max) (50%, P < 0.05) for uptake of the glucose analog [3H]2-deoxyglucose (3H2-DOG), when compared to cells chronically adapted to physiologic glucose concentrations (8 mmol/l). The increase in GLUT1 protein was sustained at 3 months, the latest time point tested (77% above control, P < 0.01). In contrast, hypertonic mannitol had no effect on GLUT1 protein levels. Insulin-like growth factor I (IGF-I; 30 ng/ml) increased the uptake of 3H2-DOG by 28% in 8 mmol/l glucose-treated cells (P < 0.05) and by 75% in cells switched to 20 mmol/l glucose for 3 days (P < 0.005). These increases in 3H2-DOG uptake occurred despite a lack of effect of IGF-I on GLUT1 protein levels (P > 0.5 vs. control). Therefore, hyperglycemia and IGF-I treatment both lead to increases in mesangial cell glucose uptake, and hyperglycemia induces increased GLUT1 expression, which can directly lead to the pathological changes of diabetic nephropathy. The effects of high glucose and of IGF-I to stimulate 3H2-DOG uptake also appear to be additive.

Optical frequency standard for optical fiber communication based on the Rb 5s --> 5d two-photon transition

We report an optical frequency standard based on the 5s --> 5d two-photon transition in Rb atoms. The frequency of a lambda = 778 nm diode laser was locked to the two-photon transition. Second-harmonic generation and an optical phase-locked loop were used to transfer the frequency stability to lambda = 1.556 mum for use in optical fiber communication applications.

Sequence dependent hypermutation of the immunoglobulin heavy chain in cultured B cells

The variable (V) regions of immunoglobulin heavy and light chains undergo high rates of somatic mutation during the immune response. Although point mutations accumulate throughout the V regions and their immediate flanking sequences, analysis of large numbers of mutations that have arisen in vivo reveal that the triplet AGC appears to be most susceptible to mutation. We have stably transfected B cell lines with gamma2a heavy chain constructs containing TAG nonsense codons in their V regions that are part of either a putative (T)AGC hot spot or a (T)AGA non-hot spot motif. Using an ELISA spot assay to detect revertants and fluctuation analysis to determine rates of mutation, the rate of reversion of the TAG nonsense codon has been determined for different motifs in different parts of the V region. In the NSO plasma cell line, the (T)AGC hot spot motif mutates at rates of approximately 6 x 10(-4)/bp per generation and approximately 3 x 10(-5)/bp per generation at residues 38 and 94 in the V region. At each of these locations, the (T)AGC hot spot motif is 20-30 times more likely to undergo mutation than the (T)AGA non-hot spot motif. Moreover, the AGA non-hot spot motif mutates at as high a rate as the hot spot motif when it is located adjacent to hot spot motifs, suggesting that more extended sequences influence susceptibility to mutation.

[Clinical and experimental study on improving cellular immunological function of uterine myoma patients by xiaoliu tablet]

OBJECTIVE

To explore the effect of Xiaoliu Tablet (XLT) in treating uterine myoma (UM) and the relationship between effect and the cellular immunological function of the UM patients.

METHODS

Seventy-one UM patients by treatment with XLT was observed. The activities of natural killer (NK) cells of 50 patients and 30 normal women were determined.

RESULTS

There were good effect in reducing the volume of myoma and improving the menses by XLT, especially in patients whose myoma were singly and small. The activity of NK cells of these patients (24.61 +/- 6.04%, n = 50) was significantly different from that of normal women (45.42 +/- 9.05%, n = 30), P < 0.01. There was a notable rise of NK cells of the patients (37.54 +/- 5.01%, n = 39), after the treatment of six months by XLT (P < 0.01).

CONCLUSION

Improving the immunological function might be one of the mechanisms of the effect of XLT.

Effect of human vitreous and hyalocyte-derived factors on vascular endothelial cell growth

PURPOSE

In the present study we have examined the effects of human vitreous and hyalocyte-conditioned medium on human umbilical vein endothelial cells (HUVEC).

METHODS

Human umbilical vein endothelial cells were cultured and treated in quadruplicate with human vitreous and hyalocyte-conditioned medium at different concentrations. Cell numbers were counted on days 1, 3, 5 and 7. Morphological changes and the viability of cells after treatment were also monitored.

RESULTS

The results indicate that both human vitreous and hyalocyte-conditioned medium inhibit proliferation and reduce the viability of HUVEC in vitro. These inhibitory effects were dose- and time-dependent.

CONCLUSIONS

The observations suggest that human hyalocytes and vitreous contain anti-angiogenic factors that influence vascular endothelial cell-growth. These results, combined with those of previous studies, may yield important information about the functional role of vitreous and hyalocytes in intraocular vascular regression.