Oxygen sensors based on luminescence quenching: interactions of pyrene with the polymer supports

Oxygen quenching of pyrene has been studied in a diverse series of polymers. Most measurements were made using homo- or copolymers containing a poly(dimethylsiloxane) region. Systematic variations in the polymer properties have been made in order to delineate the structural features important for satisfactory use as supports for oxygen sensors. In particular, quenching behavior was examined as a function of the type and amount of copolymer cross-linkers; these were added to produce domains of different polarity and rigidity that would segregate the sensor molecule. A domain model (Xu, W.; et al. Anal. Chem. 1994, 66, 4133-4141) was used to explain the variations in oxygen-quenching properties as a function of additives and cross-linkers. The relative affinity of the different domains for the pyrene and the efficacy of the domains for oxygen quenching controls the overall behavior of the sensing response.

Human obesity does not segregate with the chromosomal regions of Prader-Willi, Bardet-Biedl, Cohen, Borjeson or Wilson-Turner syndromes

Prader-Willi, Bardet-Biedl, Cohen, Borjeson and Wilson-Turner syndromes are genetic disorders characterized by obesity and other diverse abnormalities. These disorders have been mapped to their respective chromosomal regions, and we hypothesize that each region contains a gene or genes important in the regulation of body weight. We tested this hypothesis by genotyping sibling pairs (n = 207; 17 markers) from 44 families who were segregating an extreme obesity phenotype but were otherwise clinically normal. The number of alleles shared between siblings from these chromosomal regions did not correlate with similarity in body mass index (kg/m2). If genes in these regions contribute to non-syndromal obesity, the prevalence is low and the corresponding alleles are rare.

[An investigation and design of apparatus for measuring fetal lung maturity]

Clinically, the authorized method for determing fetal lung maturity is the measurement of the ratio of surface-active L/S in amniotic fluid. To set up new, simple, rapid and accurate method, an apparatus for measuring fetal lung maturity was made. The paper describes the basic principle and working procedure of the apparatus. 148 amniotic fluid specimens from different pregnancies were measured by means of the apparatus. The result was compared with the L/S. The sensitivity of measurement was 95%, specificity 91%, and accuracy 93%. The operation of the apparatus is simple, convenient and rapid. A small quantity of amniotic fluid is needed. In conclusion, the expected result was attained. The apparatus is of great importance to clinical application.

[p53 gene point mutation in human colorectal carcinoma]

We introduced two modified assay systems, PCR-SSCP and PCR-direct sequencing for the identification of structure aberration at p53 exon 7 in 22 colorectal carcinomas and 1 metastatic lymph node. The data indicated that 27.2% (6/22) colorectal carcinomas and one metastatic lymph node were shown to contain the point mutations in codons 245, 251, 259 and 260 of exon 7. One half of all the mutations was G:c to A:T transition in codon 245. Other mutation patterns were base insertion and deletion. All positive point mutations of p53 exon 7 existed in colon carcinomas in this study. The point mutation in p53 exon 7 was usually associated with poorly differentiated primary carcinomas (P = 0.0178) and the mutation rate of was higher in Duckes C stage of the disease than in stage Duckes A and B (P = 0.0361). Thus p53 exon 7 point mutation in primary colorectal tumors and regional lymph nodes may identity a subgroup of colorectal cancer patients with more aggressive disease and may be as a new tumor markers for assessing the prognosis of colorectal carcinomas.

Signaling through the interleukin 2 receptor beta chain activates a STAT-5-like DNA-binding activity

To explore the possible involvement of STAT factors ("signal transducers and activators of transcription") in the interleukin 2 receptor (IL-2R) signaling cascade, murine HT-2 cells expressing chimeric receptors composed of the extracellular domain of the erythropoietin receptor fused to the cytoplasmic domains of the IL-2R beta or -gamma c chains were prepared. Erythropoietin or IL-2 activation of these cells resulted in rapid nuclear expression of a DNA-binding activity that reacted with select STAT response elements. Based on reactivity with specific anti-STAT antibodies, this DNA-binding activity was identified as a murine homologue of STAT-5. Induction of nuclear expression of this STAT-5-like factor was blocked by the addition of herbimycin A, a tyrosine kinase inhibitor, but not by rapamycin, an immunophilin-binding antagonist of IL-2-induced proliferation. The IL-2R beta chain appeared critical for IL-2-induced activation of STAT-5, since a mutant beta chain lacking all cytoplasmic tyrosine residues was incapable of inducing this DNA binding. In contrast, a gamma c mutant lacking all of its cytoplasmic tyrosine residues proved fully competent for the induction of STAT-5. Physical binding of STAT-5 to functionally important tyrosine residues within IL-2R beta was supported by the finding that phosphorylated, but not nonphosphorylated, peptides corresponding to sequences spanning Y392 and Y510 of the IL-2R beta tail specifically inhibited STAT-5 DNA binding.

[Total pelvic exenteration for local advanced rectal carcinoma: analysis of 20 patients]

20 patients of total pelvic extenteration (TPE) were performed from 1989 to 1995 for local advanced rectal carcinoma. The incidence of operative complications was 65% with a mortality of 5%. 19 patients were followed up for 3-42 months, 7 patients died with an average life-span of 14.1 months. It seemed to us that the results of conservative therapy was usually disappointing for local advanced rectal carcinoma and and TPE is the better management of choice for relieving patient's symptoms and improving their survival rates.

Molecular genetic analysis of the duplication of human inducible nitric oxide synthase (NOS2) sequences

In previous studies, we found multiple copies of inducible nitric oxide synthase gene (NOS2)-like sequences in the human genome and mapped them to the pericentric region of chromosome 17. Here, we describe the cloning and sequencing of exon22 regions from three of these NOS2-like sequences. We have also mapped another NOS2-like sequence to human chromosome 14. Since there are multiple NOS2-like sequences present in the human genome, we have also carried out Zoo Blot hybridisation analysis using a NOS2 cDNA probe. Our data suggest that duplication of NOS2-like sequences occurred very recently in primate evolution.

A microchip glucose sensor

A major problem in development of a glucose sensor for use in an implantable artificial pancreas is the lack of reproducibility in signals from sensor to sensor. Each glucose sensor fabricated with currently used methods has a unique response to varying levels of glucose concentration and thus needs to be individually calibrated before use. We have adapted microchip manufacturing techniques for the fabrication of electrochemically based glucose sensors with standardized and reproducible function. Scanning electron microscopic study of the resulting electrode surfaces shows them to be smooth and featureless at all levels of magnification. X-ray diffraction analysis of the electrodes indicates preferential exposure of the [1,1,1] crystal interface. Cyclic voltammetry evaluation of initial sensor response to varying glucose concentrations shows excellent sensor to sensor reproducibility for all sensors made with the same underlayment. Sensors made with titanium underlayment appear to be more differentiated and thus more sensitive to variations in glucose concentration than are sensors with chromium underlayment. Although the initial response of microchip glucose sensors appears to be standardized and reproducible, additional development of an appropriate electrical insulation material is required before long-term study of signal stability is feasible.

[Correlation study of allelic gene deletion of nm23-H1 and human colorectal carcinoma metastasis]

In recent years, a tumor suppressor gene nm23 has been found to be associated with decreased tumor metastatic potential. Allelic deletion, mutation and low expression of this gene has been correlated with tumor metastatic potential in a number of tumors. There are two known isotypes of human nm23 gene, named nm23-H1 and nm23-H2. We examined DNA from 23 cases of colorectal carcinomas and their corresponding normal mucosa using Southern blot hybridization with nm23-H1 cDNA probe. Five cases with allelic deletion of nm23-H1 gene were found, with allelic deletion rate of 57. 1% (4/7) in cases with metastasis to lymph node, liver or other organs, and 6.2% (1/16) in cases without metastases (P < 0.005). There is no correlation between allelic deletion and tumor size, location or differentiation. This result indicates that nm23-H1 gene plays an important role in the metastasis of colorectal carcinoma.

A micro carbon electrode for nitric oxide monitoring

A nitric oxide (NO) probe, consisting of a micro carbon fiber working electrode, 10 microns diameter, a platinum counter electrode, and a silver/silver chloride (Ag/AgCl) reference electrode, has been developed. The carbon fiber working electrode is covered with a Nafion cation exchange membrane. Using differential pulse voltammetry (DPV), we found the NO to N2O reduction current peak at approximately -1.35 V versus Ag/AgCl. This has been reported by others. The DPV current outputs are linearly related to dissolved NO concentrations [NO] in the 2-10 microM range. Catecholamines were found not to interfere with the reduction signal. The Nafion membrane also prevents interference by NO2-, NO3-, and amino acids at normal physiologic pH (pH 7.4). The effects of O2 are accounted for through sampling and subtracting background currents from the peak current. To increase sensitivity and shorten response time, a method of integrated pulse amperometry (IPA) was used for the study. The IPA charge outputs (delta C) are linear to the dissolved [NO] in the 50-350 nM range. The carbon fiber electrode has the potential of being miniaturized to a smaller electrode, allowing detection of NO released from the subendothelial space.

[In vitro antibacterial activity of sulperazone on multi-resistant strains of bacteria from burn wounds]

Sulperazone (SLP), a combination of sulbactam (beta-lactamase inhibitor) with cefoperazone (CFP), was studied in vitro for its sensitivity to multi-resistant strains of bacteria isolated from burn wounds. The results showed that the sensitive rate of gram-negative bacteria to SLP was 77.3% (n = 163), higher than that of CFP (45.0%, n = 169) (P < 0.01). The rate of pseudomonas aeruginosa which was common among the gram-negative bacteria was 88.9% (n = 45), much higher than that of CFP (71.7%, n = 46) (P < 0.05). The rate of bacterium anitratum was 100%, and it was resistant to CFP (P < 0.01). The sensitive rate of gram-positive bacteria to SLP was 37.5% (n = 128) but to CFP was 24.6% (n = 126) (P < 0.05). The rate of staphylococcus aureus which was common in gram-positive bacteria was 42.6% (n = 61), much higher than that of CFP (21.3%, n = 61) (P < 0.05). It is indicated that sulbactam inhibits most beta-lactamases produced by common bacterial pathogens and makes antibiotics restore the sensitivity to resistant strains. Sulperazone is promising in the treatment of burn infection.

A nitric oxide sensor using reduction current

Nitric oxide (NO) has a wide range of biologic activity. Methods commonly used for the detection of biologically derived NO are indirect and measure only the amount of NO released during an interval of time. An electrochemical method available is capable of being direct and continuous but is subject to interference. The recent explosion of scientific research into NO activity requires better methods of NO detection. This article reports a new NO electrochemical sensing method and sensor design. The tip of the sensor is covered with a hydrophobic membrane and contains an internal electrolyte. Platinum is used for the working and counter electrodes and silver/silver bromide (Ag/AgBr) for the reference electrode. The components of the internal electrolyte are potassium bromide and sulfuric acid. The NO that diffuses to the working electrode is first oxidized to NO+; the NO+ is reduced to NO; and the reduction current is determined. An integrated pulsed amperometric method is used to achieve the redox of NO and the measurement and integration of the reduction current. The results show that the NO sensor is sensitive and has a rapid response and less interference.

[Enzyme-linked immunoadsorbent assays for myelin basic protein and antibodies to myelin basic protein in serum and CSF of patients with diseases of the nervous system]

Simplified enzyme-linked immunoadsorbent assays (ELISA) for myelin basic protein (MBP) and antibodies to myelin basic protein (Anti-MBP) have been used to test 337 patients with diseases of the nervous system including 36 compressive diseases (CMP), 33 multiple sclerosis (MS), 34 cerebrovascular diseases (CVD), 31 inflammatory diseases of central nervous system (ID), 161 epilepsy (EP) and 42 other nervous diseases (OND). Comparison of results among various groups indicates that serum mean MBP values of CMP, MS, CVD, ID and EP groups are significantly higher than those of OND group and normal control (P < 0.01). The serum mean MBP value of 33 acute trauma patients with spine fracture and paraplegia, the majority of CMP group, is the highest compared with MS group (P < 0.05), CVD, ID and EP groups (P < 0.01). CSF mean MBP value of 15 CVD patients is markedly greater than that of OND group (P < 0.05). No statistically significant differences are found in serum MBP values between OND group and normal control, and in serum and CSF Anti-MBP values among six groups by using our method.

Growth attenuation in a human prostate cell line mediated by a phorbol ester

Human prostatic cancer cells JCA-1 were induced with a phorbol ester 12-o-tetradecanoylphorbol-13-acetate (TPA), and cell growth differentiation were analyzed. Within hours of exposure to TPA, cell proliferation decreased and reached approximately 80% reduction after 3 days, as determined by [3H]thymidine incorporation and cell counting. Cell cycle analysis revealed a blocking of cells entering into the replicating S and G2M phases from the G1 phase. The TPA induced cells had a reduced growth rate but remained viable. The growth-modulating activity of TPA was similarly observed with LNCaP cells. Agarose gel electrophoresis of the chromosomal DNA from induced cells exhibited a non-fragmented pattern excluding the possibility of cell apoptosis. In parallel to the growth reduction, the TPA induced cells became larger in size showing dendrite like cytoplasmic extensions. Furthermore, JCA-1 cells treated with TPA acquired the expression of cytokeratin 18 and increased the expression of actin and vimentin by 300%. These results indicate an induced growth reduction accompanied by cellular differentiation of the prostatic cancer cells.

Treatment of intracranial germinoma

In 31 patients with intracranial germinoma who received radiotherapy, 15 were operated on, and 13 were treated with CSF shunt (7) and external ventricular drainage (6). After radiotherapy, clinical symptoms were improved in 93.5% of the patients. Follow-up of 16 patients for 2 to 14 years showed better results. We consider that initial treatment with radiotherapy may be appropriate for germinomas because of its high radiosensitivity. If hydrocephalus developed, external ventricular drainage combined with radiotherapy was performed, but shunting operation might be avoided because of potential peritoneal seedings of germinomas. In addition to chemotherapy, re-irradiation is an effective method for recurrent germinoma.

[p53 gene deletion and abnormal expression in gastric carcinoma]

We studied p53 gene at the DNA and protein level in human gastric cancer tissues and corresponding normal gastric mucosae from 20 cases of patients undergone radical surgery. By Southern blotting, the p53 gene was found to be partially deleted in 30% (6/20) of gastric cancer tissues. ABC immunohistochemical study of p53 expression was carried out on cryostat sections using monoclonal antibodies (PAb 1801) to p53. High level expression of mutated p53 protein was detected in 55% (11/20) gastric cancer tissues. The staining pattern was intranuclear and/or intracytoplamic. There was no detectable staining of any of the normal gastric tissues with 1801 antibody. The positive rate of p53 overexpression was higher in poorly-differenciated glandular carcinomas than well-differenciated cancer (P = 0.0116). Highly significant association exists between high level p53 expression and allele deletion (r = 0.59). The date indicate that inactivation of p53 gene is important in human gastric carcinogenesis and tumor progression. The assay of p53 gene structure and products may provide new biologically relevant tumor marks for predicting the behavior of gastric carcinomas, identifying more aggressive tumors, determining prognosis of the patients and guiding treatment.

Growth regulation and cellular changes during differentiation of human prostatic cancer LNCaP cells as induced by T lymphocyte-conditioned medium

Human prostatic epithelial cells from an androgen-dependent LNCaP cell line were examined in response to conditioned medium (CM) derived from phytohemagglutinin (PHA)-stimulated lymphocytes. Addition of CM caused a greater than 70% reduction of cell proliferation by cell counting and cell cycle. These cells showed G1 phase arrest and the clonogenicity was reduced. The growth-modulating effect was dose-dependent and not due to cell lysis or apoptosis. The binding of androgen to androgen receptor on these cells showed approximately 50% reduction, underlining a proliferation reduction mechanism. The prostate-specific antigen (PSA) was downregulated to approximately 75% during the process. Cell morphology showed dendritic processes extending from cytoplasm and other neuroendocrine cell characteristics. The expression of several cytoskeleton and intracellular proteins increased as determined by immunostaining on slides and by ELISA procedures. These included vimentin, correlating to cell shape changes, cytokeratins 8 and 18, associated with differentiated cell types of prostate epithelia, and neuron-specific enolase and serotonin, associated with neuroendocrine cells. From these cellular changes, we can infer that the cell growth was modulated along with induction of terminal differentiation. Activated T cells were demonstrated to be important in providing the modulating activity. This growth modulator was semipurified and had an estimated molecular weight 13,000 to 24,000 Da. The activity was determined to be distinct from TGF, TNF, and some commonly known lymphokines. The interaction between lymphoid and prostatic cells in growth and development is described.

Uroporphyrinogen-III synthase: molecular cloning, nucleotide sequence, expression of a mouse full-length cDNA, and its localization on mouse chromosome 7

Uroporphyrinogen-III synthase (URO-S; EC 4.2.1.75), the fourth enzyme in the heme biosynthetic pathway, is responsible for the conversion of hydroxymethylbilane to the cyclic tetrapyrrole, uroporphyrinogen III. The deficient activity of URO-S is the enzymatic defect in congenital erythropoietic porphyria (CEP), an autosomal recessive disorder. For the generation of a mouse model of CEP, the human URO-S cDNA was used to screen 2 x 10(6) recombinants from a mouse adult liver cDNA library. Ten positive clones were isolated, and dideoxy sequencing of the entire 1.6-kb insert of clone pmUROS-1 revealed 5' and 3' untranslated sequences of 144 and 623 bp, respectively, and an open reading frame of 798 bp encoding a 265-amino-acid polypeptide with a predicted molecular mass of 28,501 Da. The mouse and human coding sequences had 80.5 and 77.8% nucleotide and amino acid identity, respectively. The authenticity of the mouse cDNA was established by expression of the active monomeric enzyme in Escherichia coli. In addition, the analysis of two multilocus genetic crosses localized the mouse gene on chromosome 7, consistent with the mapping of the human gene to a position of conserved synteny on chromosome 10. The isolation, expression, and chromosomal mapping of this full-length cDNA should facilitate studies of the structure and organization of the mouse genomic sequence and the development of a mouse model of CEP for characterization of the disease pathogenesis and evaluation of gene therapy.

Metabolic approach for regulation of IL-1 beta in vivo

IL-1 beta, the autoantibodies to IL-1 beta and IL-1 beta-containing immune complex in pleural effusion and cerebrospinal fluid were detected using anti-recombinant human IL-1 beta monoclonal antibody. The results indicate that IL-1 beta is detectable in some cases, and the amounts decrease gradually with the chemotherapy following the autoantibodies and the specific detectable immune complex. These autoantibodies may have a feedback effect, inhibiting the IL-1 beta activity, and forming the immune complex to speed the clearance of activated IL-1 beta.

Characterization of measles viruses isolated after measles vaccination

Seven measles virus (MV) strains were isolated from children who developed clinical signs of fever and rash 3-9 days after measles vaccination. The nucleotide sequence of the H gene, the molecular size of the H protein, the haemadsorption activity on African green monkey red blood cells, and antigenicity as determined by virus neutralization revealed that one strain was of the vaccine type and the remaining six were the wild virus type. Isolation of the virus directly from patients suspected of a vaccine-induced side-reaction and subsequent characterization of such isolated virus may be useful in differentiation between vaccine-induced side-reactions and natural measles.

Crystal structure of a paired domain-DNA complex at 2.5 A resolution reveals structural basis for Pax developmental mutations

The 2.5 A resolution structure of a cocrystal containing the paired domain from the Drosophila paired (prd) protein and a 15 bp site shows structurally independent N-terminal and C-terminal subdomains. Each of these domains contains a helical region resembling the homeodomain and the Hin recombinase. The N-terminal domain makes extensive DNA contacts, using a novel beta turn motif that binds in the minor groove and a helix-turn-helix unit with a docking arrangement surprisingly similar to that of the lambda repressor. The C-terminal domain is not essential for prd binding and does not contact the optimized site. All known developmental missense mutations in the paired box of mammalian Pax genes map to the N-terminal subdomain, and most of them are found at the protein-DNA interface.