A novel anionic inward rectifier in native cardiac myocytes

Although the cationic inward rectifiers (Kir and hyperpolarization-activated I(f) channels) have been well characterized in cardiac myocytes, the expression and physiological role of anionic inward rectifiers in heart are unknown. In the present study, we report the functional and molecular identification of a novel chloride (Cl(-)) inward rectifier (Cl.ir) in mammalian heart. Under conditions in which cationic inward rectifier channels were blocked, membrane hyperpolarization (-40 to -140 mV) activated an inwardly rectifying whole-cell current in mouse atrial and ventricular myocytes. Under isotonic conditions, the current activated slowly with a biexponential time course (time constants averaging 179.7+/-23.4 [mean+/-SEM] and 2073.6+/-287.6 ms at -120 mV). Hypotonic cell swelling accelerated the activation and increased the current amplitude whereas hypertonic cell shrinkage inhibited the current. The inwardly rectifying current was carried by Cl(-) (I(Cl.ir)) and had an anion permeability sequence of Cl(-)>I(-)>>aspartate. I(Cl.ir) was blocked by 9-anthracene-carboxylic acid and cadmium but not by stilbene disulfonates and tamoxifen. A similar I(Cl.ir) was also observed in guinea pig cardiac myocytes. The properties of I(Cl.ir) are consistent with currents generated by expression of ClC-2 Cl(-) channels. Reverse transcription polymerase chain reaction and Northern blot analysis confirmed transcriptional expression of ClC-2 in both atrial and ventricular tissues and isolated myocytes of mouse and guinea pig hearts. These results indicate that a novel I(Cl.ir) is present in mammalian heart and support a potentially important role of ClC-2 channels in the regulation of cardiac electrical activity and cell volume under physiological and pathological conditions.

Plastic bending of sapphire fibers for infrared sensing and power-delivery applications

Sapphire fibers with diameters of 325-850 microm were plastically bent by CO(2) laser beams with typical bending radii as small as 2.8 mm. The additional optical loss caused by a single bend was less than 0.1 dB (at 900 nm), the damage threshold of the bent fibers was higher than 150 MW/cm(2) for Nd:YAG laser pulses, and the high mechanical strength of the bending area was also proved. Several successful applications of bent sapphire fibers have shown that plastically bent sapphire fibers are promising for use in IR sensing and power-delivery applications.

[Amplification, cloning and expression of a gene encoding hexose transporter of Plasmodium falciparum]

OBJECTIVE

To amplify, clone and express of a gene encoding hexose transporter of Plasmodium falcipuram (PfHT1) from Southern China isolate FCC1/HN for studing the immune of recombinant which protective from malaria parasite infection.

METHODS

Cultivation of P. falciparum isolate FCC1/HN in vitro; extraction of genomic DNA from FCC1/HN using the alkali specific cleavage method; PCR amplification of PfHT1 and cloning into eukaryotic expression vector, pEGFPN3. The recombinant as introduced into mammalian cells, HEPG2 by using liposome-mediated transfection.

RESULTS

The gene encoding PfHT1 was specifically amplified from the genomic DNA of P. falciparum isolate FCC1/HN. The size of amplified fragment was 1,516 base pair. The eukaryotic expression recombinant, pN3-HT1, was constructed and expressed steadily in the hepatocarcinoma cell lines, HEPG2.

CONCLUSION

The gene encoding PfHT1 was successfully amplified and cloned. The pN3-HT1/HEPG2 cell line was built for expressing fusion protein of GFP-HT1.

[Study on the volatile oil of Nardostachys chinensis]

The volatile oil of Nardostachys chinensis Batal has been studied by GC-MS, and 21 compounds have been isolated and identified. The total content of the components are 88.51%. Major compounds have been identified as Calarene (29.44%). delta 1(10)-Aristolenone-2 (16.57%) and Jatamansinol (8.80%).

[Detection of telomerase activity in prostate needle-biopsy samples]

OBJECTIVE

To detect telomerase activity inprostate needle-biopsy samples and its role in diagnosis and prognosis of prostate cancer.

METHODS

20 tissue samples of prostate cancer tissues and 16 samples of adjacent tissues were obtained by needle-biopsy guided by transrectal B ultrasonography. 16 samples of benign prostatic hyperplasia tissues were obtained by prostatectomy and were confirmed pathologically. Telomerase activity was revealed by modified PCR-based telomeric repeat amplication protocol (TRAP)-silver staining assay.

RESULTS

Telomerase activity was revealed in 18 cases of prostate cancer. In tissues adjacent to prostate cancer, telomerase activity was found in 7 of 11 cases of prostatic intraepithelial neoplasia (PIN), and in 2 of 5 cases of BPH. None of tissue samples from patients with BPH showed telomerase activity.

CONCLUSIONS

Telomerase activity in prostate needle-biopsy samples might be an useful marker for detecting prostate cancer and biological malignancy.

Expression of heat shock protein 90 beta in human gastric cancer tissue and SGC7901/VCR of MDR-type gastric cancer cell line

OBJECTIVE

To examine the expression of heat shock protein (HSP) 90 beta in human gastric cancer tissue and SGC7901/VCR of MDR-type gastric cancer cell line.

METHODS

Immunohistochemical staining and in situ hybridization methods.

RESULTS

Heat shock protein 90 beta was mainly located in the cell cytoplasma and weakly expressed in non-cancerous gastric mucosa. The expression rates of HSP90 beta in normal gastric mucosa, gastritis and paracancer tissues were 11.76%, 13.04% and 11.42% respectively, and there were no significant differences between them (P > 0.05). The expression of HSP90 beta was increased in gastric cancer. The positive rate of HSP90 beta in gastric cancer tissue was 30.00%, and was higher than non-cancerous gastric mucosa (P < 0.05). The expression rates of HSP90 beta in well differentiated, moderately differentiated, poorly differentiated gastric cancer and mucinous carcinoma were 15.38%, 31.25%, 33.33%, and 42.85% respectively. The expression of HSP90 beta in SGC7901/VCR of MDR-type gastric cell line was higher than in its parental cell line SGC7901. In situ hybridization showed that the positive signal of HSP90 beta was mainly located in the cell cytoplasma.

CONCLUSIONS

The expression of HSP90 beta was higher in gastric cancer tissue than in non-cancerous gastric mucosa. In gastric cancer tissue, the expression of HSP90 beta was greater in poorly differentiated cancer tissue, and in SGC7901/VCR of MDR-type gastric cancer cell line the expression of HSP90 beta was higher than that in its parental cell line SGC7901.

Standard growth curve chart for body height of Chinese adolescent for orthodontic diagnosis

OBJECTIVE

To make a standard growth curve chart on the body height of Chinese adolescents.

METHODS

Statistical data from 32,524 Sichuan students aged 7 to 19 years were surveyed in 1995. Mean values of the annual increment of body height and the ages of the pubertal growth periods were analyzed.

RESULTS

During the period between 9 and 13 years of age, females grow faster than their male peers. After age 13 years, males surpass females, and the difference in physical growth and development becomes more pronounced.

CONCLUSIONS

The new standard growth curve chart on the body height of Chinese adolescent may be applied to better understand the growth pattern of Chinese orthodontic patients.

Suppressive action produced by beta-amyloid peptide fragment 31-35 on long-term potentiation in rat hippocampus is N-methyl-D-aspartate receptor-independent: it's offset by (-)huperzine A

Extracellular recordings of field potential from CA1 region of rat hippocampal slices were used to observe the effects of a shorter synthetic fragment of beta-amyloid peptide (A beta31-35) on the induction of long-term potentiation (LTP) and the action of (-)huperzine A, a potent acetylcholinesterase (AChE) inhibitor on these processes was also observed. The results showed that: (1) 0.1 microM A beta31-35 suppressed the induction of LTP in a similar mode as the longer fragment A beta25-35, did, while they did not change the amplitude of the baseline population spike (PS); (2) when PSs were recorded separately in Mg2+-free medium, which unveils the N-methyl-D-aspartate (NMDA)-mediated responses, both A beta31-35 and A beta25-35 showed little effect on the components of multiple PSs; (3) two concentrations of 0.1 microM or 1.0 microM (-)huperzine A showed no effects on the PS amplitude while the latter could enhance the LTP and (4) co-administration of (-)huperzine A with 0.1 microM concentration could block most of the suppressive action induced by A beta31-35 or A beta25-35 upon the LTP. The results suggest that the shorter fragment A beta31-35, is long enough to suppress the induction of LTP and these two fragments might suppress the induction of LTP through a NMDA receptor-independent pathway that involves cholinergic terminals in hippocampus.

Purinoceptor-coupled Cl- channels in mouse heart: a novel, alternative pathway for CFTR regulation

1. P2-purinoceptors couple extracellular ATP to the activation of a Cl- current (ICl,ATP) in heart. We studied the molecular mechanism and intracellular signalling pathways of ICl,ATP activation in mouse heart. 2. Extracellular adenosine-5'-O-(3-thiotriphosphate) (ATPgammaS; 100 microM) activated ICl,ATP in both atrial and ventricular myocytes. A specific PKC inhibitor, bisindolylmaleimide blocked the effect of ATPgammaS while a PKC activator, phorbol 12, 13-dibutyrate (PDBu) activated a current with identical properties to ICl,ATP. Maximal activation of ICl,ATP by ATPgammaS or PDBu occluded further modulation by the other agonist, suggesting that they may activate the same population of Cl- channels. 3. Isoprenaline increased ICl,ATP pre-activated by ATPgammaS or PDBu, while isoprenaline or forskolin alone failed to activate any Cl- current in these myocytes. Adenosine 3',5'-cyclic monophosphothionate, a PKA inhibitor, prevented ATPgammaS or PDBu activation of ICl,ATP. Thus, ICl,ATP is regulated by dual intracellular phosphorylation pathways involving both PKA and PKC in a synergistic manner similar to cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels. 4. Glibenclamide (50 microM) significantly blocked ICl,ATP activated by ATPgammaS or by the CFTR channel activator, levamisole. 5. The slope conductance of the unitary ICl,ATP in cell-attached patches was 11.8 +/- 0.3 pS, resembling the known properties of CFTR Cl- channels in cardiac myocytes. 6. The reverse transcription polymerase chain reaction and Northern blot analysis revealed CFTR mRNA expression in mouse heart. 7. We conclude that ICl,ATP in mouse heart is due to activation of CFTR Cl- channels through a novel intracellular signalling pathway involving purinergic activation of PKC and PKA.

Use of molecularly imprinted polymers in a biotransformation process

Molecularly imprinted polymers are highly stable and can be sterilised, making them ideal for use in biotransformation process. In this communication, we describe a novel application of molecularly imprinted polymers in an enzymatic reaction. The enzymatic condensation of Z-L-aspartic acid with L-phenylalanine methyl ester to give Z-L-Asp-L-Phe-OMe (Z-aspartame) was chosen as a model system to evaluate the applicability of using molecularly imprinted polymers to facilitate product formation. When the product-imprinted polymer is present, a considerable increase (40%) in product yield is obtained. Besides their use to enhance product yields, as demonstrated here, we suggest that imprinted polymers may also find use in the continuous removal of toxic compounds during biochemical reactions.

[Detection of stable expression of human interlukin-2 gene in transfected keratinocytes]

OBJECTIVE

To investigate the stable expression and secretion of human interlukin-2 gene in transfected keratinocytes.

METHODS

Keratinocytes were transfected with lipofectamine and selected by G418. Then the samples were analyzed with the techniques of DNA dot blot, RNA dot blot, hybridization in situ, immunohistochemistry, Western blot and MTT.

RESULTS

The positive signals were observed in transfected keratinocytes by DNA dot blot, RNA dot blot, hybridization in situ and immunohistochemistry. With Western blot analysis, a specific band exhibiting a molecular weight of 15,000 was detected in transfected keratinocytes, which was in acordance with that of IL-2. The expression of IL-2 can maintain for up to 1 month. The amounts of IL-2 in the supernatants of two and four passages transfected keratinocytes were 27.7 U/ml and 15.0 U/ml, respectively.

CONCLUSION

Keratinocytes have the potential for stable gene expression and secretion of active transgene products. Thus, it is possible to use keratinocytes as a target cell for gene transfection, gene expression and even gene therapy.

[Studies on standard growth curve chart on body weight of adolescent Chinese for orthodontic diagnosis]

OBJECTIVE

To establish the first new annual increase and growth curve charts on the body weight of Chinese children.

METHODS

Data were surveyed in 1995, which were obtained from subjects consisting of 32524 students aged from 7 to 19 years in Sichuan province.

RESULTS

Mean values of the annual increment of body weight, sex and area difference were analyzed.

CONCLUSION

The new standard growth curve chart on the body weight is very useful for orthodontic diagnosis, treatment and prognosis.

Growth and glucose repression are controlled by glucose transport in Saccharomyces cerevisiae cells containing only one glucose transporter

A set of Saccharomyces cerevisiae strains with variable expression of only the high-affinity Hxt7 glucose transporter was constructed by partial deletion of the HXT7 promoter in vitro and integration of the gene at various copy numbers into the genome of an hxt1-7 gal2 deletion strain. The glucose transport capacity increased in strains with higher levels of HXT7 expression. The consequences for various physiological properties of varying the glucose transport capacity were examined. The control coefficient of glucose transport with respect to growth rate was 0.54. At high extracellular glucose concentrations, both invertase activity and the rate of oxidative glucose metabolism increased manyfold with decreasing glucose transport capacity, which is indicative of release from glucose repression. These results suggest that the intracellular glucose concentration produces the signal for glucose repression.

Frequency of the fragile X syndrome in Chinese mentally retarded populations is similar to that in Caucasians

Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. We report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals. We found that 2.8% of the Chinese MR population screened by DNA analysis had the fragile X full mutation. Our screening indicated that the fragile X syndrome prevalence was very close to that of Caucasian subjects. In addition, we found that 62.5% of fragile X chromosomes had a single haplotype for DXS548-FRAXAC1 (21-18 repeats) which was present in only 9.7% of controls. This unique distribution of microsatellite markers flanking the FMR1 CGG repeats suggests that the fragile X syndrome in Chinese populations, as in the Caucasian, may also be derived from founder chromosomes.

[Studies on standard growth curve chart on body height of Chinese adolescent for orthodontic diagnosis]

OBJECTIVE

To make a standard growth curve chart on the body height of Chinese adolescent.

METHODS

Statistical data were surveyed in 1995, which were obtained from subjects consisting of 32,524 students aged from seven to nineteen years in the province of Sichuan.

RESULTS

Mean values of the annual increment of body height and the ages of the pubertal growth periods were analyzed.

CONCLUSION

The new standard growth curve chart on the body height of adolescent chinese were applied for better understanding the growth pattern of chinese orthodontic patients.

Characterization of three distinct cDNA clones encoding cysteine proteinases from maize (Zea mays L.) callus

In previous work, a 33 kDa cysteine proteinase was found in callus initiated from maize (Zea mays L.) resistant to fall armyworm feeding. A callus cDNA library from the maize inbred Mp708 was screened with oligonucleotides derived from the N-terminal amino acid sequence of the 33 kDa proteinase and several cDNA clones were isolated and sequenced. A cDNA clone encoding the 33 kDa cysteine proteinase, mir1, was identified. Two additional clones, mir2 and mir3, encoding putative cysteine proteinases were also identified. mir2 and mir3 are distinct from mir1 and each other, but show a high degree of homology. All of the mir cDNA clones map to distinct sites on the maize genome. Amino acid sequences encoded by the mir clones are similar to other known cysteine proteinases and are most closely related to the oryzain-alpha and -beta precursors. The ERFNIN motif and a 12 amino acid conserved sequence are present in the propeptide region of the putative proteinases encoded by mir clones. mir2 and mir3 appear to have C-terminal extensions. The phylogenetic tree of nucleotide sequences of mir1, mir2, mir3 and other representative cysteine proteinases from protozoa, plants and animals was constructed.

Functional expression, quantification and cellular localization of the Hxt2 hexose transporter of Saccharomyces cerevisiae tagged with the green fluorescent protein

The Hxt2 glucose transport protein of Saccharomyces cerevisiae was genetically fused at its C-terminus with the green fluorescent protein (GFP). The Hxt2-GFP fusion protein is a functional hexose transporter: it restored growth on glucose to a strain bearing null mutations in the hexose transporter genes GAL2 and HXT1 to HXT7. Furthermore, its glucose transport activity in this null strain was not markedly different from that of the wild-type Hxt2 protein. We calculated from the fluorescence level and transport kinetics that induced cells had 1.4x10(5) Hxt2-GFP molecules per cell, and that the catalytic-centre activity of the Hxt2-GFP molecule in vivo is 53 s-1 at 30 degrees C. Expression of Hxt2-GFP was induced by growth at low concentrations of glucose. Under inducing conditions the Hxt2-GFP fluorescence was localized to the plasma membrane. In a strain impaired in the fusion of secretory vesicles with the plasma membrane, the fluorescence accumulated in the cytoplasm. When induced cells were treated with high concentrations of glucose, the fluorescence was redistributed to the vacuole within 4 h. When endocytosis was genetically blocked, the fluorescence remained in the plasma membrane after treatment with high concentrations of glucose.

First trial of home ECG and blood pressure telemonitoring system in Macau

OBJECTIVE

To determine the feasibility of home monitoring of patients with cardiac disease or hypertension.

METHODS

An improved home electrocardiographic and blood pressure telemonitoring system linked to a central workstation was tested in 10 patients in Macau for 3 months.

RESULTS

The total number of connections was 1377. Of the automatic alarm connections, 32.5% were false positive, with the percentage of false positives ranging from 7.6 to 54.6 for different patients. Both patients and physicians found the system easy to use.

CONCLUSIONS

Further investigation is required to match the number of patients with the system capacity. A more robust dysrhythmia detection algorithm is needed to reduce the number of false alarms. Nevertheless, the results were sufficiently good that the trial is being expanded.

5-HTTLPR variants not associated with autistic spectrum disorders

To determine whether there is an association of polymorphic variants of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) and autistic spectrum disorders, we analyzed the 5-HTTLPR genotypes of 72 autistic subjects, 11 fragile X syndrome patients with autistic behavior, 43 normal subjects, and 49 fragile X syndrome non-autistic subjects. The distribution frequency of 5-HTTLPR long allele (L) and the short allele (S) variants showed no differences between subjects. Our findings do not support the hypothesis that polymorphic 5-HTTLPR variants are a susceptibility factor for autistic disorders.