Ministry of Health Clinical Practice Guidelines: Diabetes Mellitus

The Ministry of Health (MOH) have updated the clinical practice guidelines on Diabetes Mellitus to provide doctors and patients in Singapore with evidence-based treatment for diabetes mellitus. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Diabetes Mellitus, for the information of SMJ readers. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website: http://www.moh.gov.sg/content/moh_web/healthprofessionalsportal/doctors/guidelines/cpg_medical.html. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Sample treatment platform using nanoparticles to determine salinomycin in flesh and meat

In this work, we developed a sensitive and selective analytical method of determining salinomycin in flesh and meat using a lab-built laser induced fluorescence microscope (LIFM) with nanoparticles. Two types of nanoparticles, Cy5 doped core-shell silica nanoparticles as a probe and magnetic nanoparticles (MNPs) to extract the target antibiotic from the treated sample, were synthesized and modified for chemical and enzymatic binding. After optimization, the newly developed method was applied to ham, chicken, and meat samples for the quantitative determination of salinomycin. The limits of detection (LODs) obtained from the calibration curve were 48-590 pg/mL, which was about 100-fold lower than that of the ELISA method.

Cerium oxide-deposited mesoporous silica nanoparticles for the determination of carcinoembryonic antigen in serum using inductively coupled plasma-mass spectrometry

CeO2-deposited mesoporous silica nanoparticles were synthesized as a probe to determine carcinoembryonic antigen (CEA) in serum by inductively coupled plasma-mass spectrometry (ICP-MS). The prepared mesoporous nanoparticles were modified and tagged to the target for sandwich-type immunoassay. Fe3O4 magnetic nanoparticles (MNPs) were also synthesized and immobilized with antibody to extract the target biomarker. The calibration curve of the synthesized CeO2-deposited silica nanoparticles, which was plotted by the signal ratio of (140)Ce/(57)Fe measured by ICP-MS vs. the concentration of CEA, showed excellent linearity and sensitivity owing to the signal amplification and low spectral interference. Under optimal conditions, the sandwich-type analytical method was applied to determine CEA in serum spiked in the range of 0.001-5 ng mL(-1) and showed a limit of detection of 0.36 ng mL(-1). Since the deposited CeO2 in the mesoporous silica layer can be substituted by other metal compounds, various kinds of metal-deposited nanoparticles can be prepared as probe materials for multiplex detection in bioanalysis.

An individual-specific gait pattern prediction model based on generalized regression neural networks

Robotics is gaining its popularity in gait rehabilitation. Gait pattern planning is important to ensure that the gait patterns induced by robotic systems are tailored to each individual and varying walking speed. Most research groups planned gait patterns for their robotics systems based on Clinical Gait Analysis (CGA) data. The major problem with the method using the CGA data is that it cannot accommodate inter-subject differences. In addition, CGA data is limited to only one walking speed as per the published data. The objective of this work was to develop an individual-specific gait pattern prediction model for gait pattern planning in the robotic gait rehabilitation systems. The waveforms of lower limb joint angles in the sagittal plane during walking were obtained with a motion capture system. Each waveform was represented and reconstructed by a Fourier coefficient vector which consisted of eleven elements. Generalized regression neural networks (GRNNs) were designed to predict Fourier coefficient vectors from given gait parameters and lower limb anthropometric data. The generated waveforms from the predicted Fourier coefficient vectors were compared to the actual waveforms and CGA waveforms by using the assessment parameters of correlation coefficients, mean absolute deviation (MAD) and threshold absolute deviation (TAD). The results showed that lower limb joint angle waveforms generated by the gait pattern prediction model were closer to the actual waveforms compared to the CGA waveforms.

Subject-specific lower limb waveforms planning via artificial neural network

Robotic is gaining its popularity in gait rehabilitation. Gait pattern planning is important, in order to ensure the gait patterns induced by robotic systems on the patient are natural and smooth. It is known that the gait parameters (stride length, cadence) are the key factors, which affect gait pattern. However, a systematic methodology for gait pattern planning is missing. Therefore, a gait pattern generation methodology, GaitGen, was proposed in our previous work. In this paper, we introduce a new model to enhance the proposed methodology for generating the joint angle waveforms of the lower limb during walking, with the gait parameters and the lower limb anthropometric data as input. The walking motion was captured with a motion capture system using passive markers. The waveforms of lower limb joint angles were calculated from the experimental data and the waveforms were then decomposed into Fourier coefficients. Therefore, each joint angle waveform can be represented by a Fourier coefficient vector containing eleven elements to facilitate the waveform analysis. Multi-layer perceptron neural networks (MLPNNs) were designed to predict the Fourier coefficient vectors for specific subject and desired gait parameters. Assessment parameters such as correlation coefficient, mean absolute deviation (MAD) and threshold absolute deviation (TAD) were calculated to examine the quality of MLPNNs' prediction. The constructed waveforms from predicted Fourier coefficient vectors were compared with the actual waveforms calculated from experimental data by using the above-mentioned assessment parameters. The results show that the constructed waveforms closely match the experimental waveforms based on the assessment parameter outcomes.

Health Promotion Board-Ministry of Health clinical practice guidelines: functional screening for older adults in the community

The Health Promotion Board (HPB) and the Ministry of Health (MOH) publish clinical practice guidelines to provide doctors and patients in Singapore with evidence-based guidance on managing important medical conditions. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the HPB-MOH clinical practice guidelines on Functional Screening for Older Adults in the Community, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Health Promotion Board website (http://www.hpb.gov.sg/uploadedFiles/HPB_Online/Publications/CPGFunctionalscreening.pdf). The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Systemic complications after head injury: a clinical review

Non-neurological organ dysfunction is common after traumatic brain injury and is an independent contributor to morbidity and mortality. It represents a risk factor that is potentially amenable to treatment, and early recognition and prompt intervention may improve outcome. This article reviews the current evidence for the mechanisms and treatment of non-neurological organ dysfunction after head injury.

Dropping mode chemiluminescence system with a poly(dimethylsiloxane) cell for applications to semiconductor processes

A lab-made chemiluminescence system with a polymer cell for the dropping mode was used to determine ultra-trace metal ions in hydrofluoric acid (HF) and the standard cleaning solution-1 (SC-1) used in semiconductor manufacturing processes. The cell was made of poly(dimethylsiloxane) (PDMS) with dimensions of about 10 mm i.d. and 8 mm in height, was cheap, disposable, chemically inert to alkalis and acids, especially HF, and was optically transparent in the visible region. A dropping method for sample injection was adopted to minimize pulsation and the dramatic pH change of the luminol-H2O2 reagent when adding the sample. The average sample weight of a single drop was 7.17 microg with a remarkable reproducibility of +/-0.37% relative standard deviation (RSD). This very small sample volume compared to the reagent volume made it possible to avoid any precipitation being formed when HF was added. For an application, Fe was determined in deionized (d.i.) water, sulfuric acid, SC-1, and a diluted HF (1:200 DHF) solution, which have been commonly used in semiconductor manufacturing processes. The limits of detections for Fe2+ in those solutions were found to be in the range of 42 to 62 pg ml(-1). Based on the analytical results, this chemiluminescence system with the PDMS cell was reproducible, resistant to HF, had less sample consumption and waste generation, and was sensitive enough to apply to the semiconductor industry as an on-line monitoring sensor. Although this chemiluminescence system does not have selectivity for each specific metal ion, it can be used as an on-line sensor to monitor the metal contamination level of Fe, Cu, Co, etc., which are major elements of concern in the semiconductor manufacturing process.

Development of an automated protein-tyrosine phosphatase 1B inhibition assay and the screening of putative insulin-enhancing vanadium(IV) and zinc(II) complexes

The inhibition of protein-tyrosine phosphatase 1B (PTP1B) is a potential target for treatment of type 2 diabetes. Vanadium and zinc metal coordinated complexes have insulin-enhancing activities, and while vanadium compounds inhibit PTP1B, little is known on the mode of action of zinc compounds. In this study we developed an automated PTP1B inhibition assay that allows for a rapid assessment of the PTP1B inhibition strength of candidate compounds. Synthetic vanadium(IV) and zinc(II) complexes were evaluated: IC50 values for vanadium complexes ranged from 0.06 to 0.8 microM whereas for zinc compounds, values were above 10 microM. Vanadium sulfate, a non-conjugated inorganic salt, had stronger inhibition activity than any of the conjugated metal complexes.

Low-Pressure ICP-AES with Electrothermal Vaporizer and a Pneumatic Nebulizer for Aqueous Sample Introduction

A typical electrothermal vaporization (ETV) using a tantalum was built for low-pressure ICP-AES. The analytical performance of the ETV was tested and compared with that of a PFA pneumatic nebulizer with a double membrane desolvator (DMD). The limits of detection of the ETV were obtained in the range of 3.4 ng to 758 ng for Zn, Cu, Co, Fe, and Mg, while those of the PFA nebulizer were in the range of 53 ppb to 286 ppb. A relative standard deviation (RSD) of 4.3 - 8.5% for ETV was obtained, while 2.15 - 6.84% RSD was found for DMD.

Manipulation of the L-arginine-nitric oxide pathway in airway inflammation induced by diesel exhaust particles in mice

The role of the L-arginine-nitric oxide (NO) pathway in bronchial asthma that is characterized by eosinophilic airway inflammation has not yet been established. We investigated the effects of three different agents on eosinophilic airway inflammation induced by the intratracheal instillation of diesel exhaust particles (DEP) in mice: L-Arginine, the substrate for NO synthases; L-N(G)-nitro-L-arginine methyl ester (L-NAME), a relatively selective inhibitor of constitutive NO synthase; and aminoguanidine, a relatively selective inhibitor of inducible NO synthase. The mice received drinking water with or without added drug for a continuous period of 9 weeks plus 4 days. Lung histology showed that airway inflammation with goblet cell proliferation induced by DEP was aggravated by the administration of L-arginine or L-NAME, whereas it was reduced by aminoguanidine. The numbers of neutrophils around the airways in animals that received plain drinking water, L-arginine, L-NAME, and aminoguanidine were 0.98+/-0.26, 3.66+/-0.81, 1.64+/-0.31, and 0.12+/-0.04 (number/mm basement membrane), respectively. The numbers of eosinophils around the airways were 0.37+/-0.08, 16.1+/-6.47, 11.1+/-3.59, and 0.21+/-0.11, respectively. The numbers of goblet cells in the bronchial epithelium were 1.67+/-0.80, 16.5+/-7.33, 19.0+/-3.40, and 0.86+/-0.41, respectively. The cellular profiles of the bronchoalveolar lavage fluid also showed that airway inflammation induced by DEP was aggravated by the administration of L-arginine or L-NAME, whereas it was reduced by aminoguanidine. These results suggest that NO produced from inducible NO synthase may have a detrimental effect on the DEP-induced airway inflammation. A relatively selective inhibition of inducible NO synthase by aminoguanidine may have therapeutic value in the inhalant injury. NO derived from constitutive NO synthase may afford protection against the airway inflammation induced by DEP.

Alteration of free radical metabolism in the brain of mice infected with scrapie agent

Alteration of free radical metabolism in the mouse brain by scrapie infection was evaluated. The infection of mice with scrapie agent, 87V strain, slightly increased the activities of catalase and glutathione-S-transferase, while it had no effect on glutathione peroxidase, glutathione reductase, and Cu, Zn-superoxide dismutase. Results show that the scrapie infection decreased the activity of mitochondrial Mn-superoxide dismutase by 50% but increased that of monoamine oxidase (p < 0.05). Scrapie infection also increased the rate of mitochondrial superoxide generation (p < 0.05). Following scrapie infection, the level of free-sulfhydryl compounds in brain homogenates slightly decreased, but the content of thiobarbituric-acid-reactive substances and malondialdehyde increased significantly. Electron microscopy indicated that the ultrastructure of mitochondria was destroyed in the brain of scrapie-infected mice. These results suggest that elevated oxygen free radical generation and lowered scavenging activity in mitochondria might cause the free radical damage to the brain. Such deleterious changes in mitochondria may contribute to the development of prion disease.

Effects of diesel exhaust on allergic airway inflammation in mice

BACKGROUND

Eosinophilic infiltration and goblet cell hyperplasia were induced by the intratracheal instillation of diesel exhaust particles and ovalbumin in mice. However, it is unknown whether its results differ from the effects of the inhalation of diesel exhaust and allergen.

OBJECTIVES

The purpose of this study was to compare the effects of diesel exhaust inhalation and intratracheal instillation of diesel exhaust particles in a murine asthma model.

METHODS

ICR mice were exposed to 3 mg soot per cubic meter of diesel exhaust for 6 weeks. After the first week, animals were sensitized by intraperitoneal injection of ovalbumin and aluminum hydroxide gel. After 5 weeks of diesel exhaust exposure, the mice were challenged with ovalbumin. The animals were killed 1, 2, 3, and 7 days after the challenge and investigated for airway inflammation, hyperplasia of goblet cells, airway hyperresponsiveness, local cytokine expression, and antigen-specific IgE and IgG1 production.

RESULTS

Exposure to diesel exhaust enhanced infiltration of eosinophils and neutrophils in murine airways even 1 day after the challenge. An increment of goblet cells under the bronchial epithelium was followed by the recruitment of inflammatory cells. Furthermore, exposure to diesel exhaust combined with ovalbumin sensitization enhanced respiratory resistance and expression of IL-5 in lung tissue and IgG1 production but not IgE. However, diesel exhaust alone did not induce pathologic changes in mice.

CONCLUSIONS

Diesel exhaust enhanced allergic airway inflammation, hyperplasia of goblet cells, and airway hyperresponsiveness caused by ovalbumin sensitization.

Involvement of superoxide and nitric oxide on airway inflammation and hyperresponsiveness induced by diesel exhaust particles in mice

We previously demonstrated that chronic intratracheal instillation of diesel exhaust particles (DEP) induces airway inflammation and hyperresponsiveness in the mouse, and that these effects were partially reversed by the administration of superoxide dismutase (SOD). In the present study, we have investigated the involvement of superoxide in DEP-induced airway response by analyzing the localization and activity of two enzymes: (1) a superoxide producer, NADPH cytochrome P-450 reductase (P-450 reductase), and (2) a superoxide scavenger, SOD, in the lungs of the exposed mice and controls. P-450 reductase was detected mainly in ciliated cells and clara cells: its activity was increased by the repeated intratracheal instillation of DEP. While CuZn-SOD and Mn-SOD were also present in the airway epithelium, their activity was significantly decreased following DEP instillation. Exposure to DEP doubled the level of nitric oxide (NO) in the exhaled air. DEP exposure also increased the level of constitutive NO synthase (cNOS) in the airway epithelium and inducible NO synthase (iNOS) in the macrophages. Pretreatment with N-G-monomethyl L-arginine, a nonspecific inhibitor of NO synthase, significantly reduced the airway hyperresponsiveness induced by DEP. These results indicate that superoxide and NO may each contribute to the airway inflammation and hyperresponsiveness induced by the repeated intratracheal instillation of DEP in mice.

Oral administration of L-arginine potentiates allergen-induced airway inflammation and expression of interleukin-5 in mice

The role of nitric oxide in the airway hyperresponsiveness and inflammation of bronchial asthma has not yet been established. However, L-arginine, the substrate for nitric oxide synthases, reportedly alleviates airway hyperresponsiveness caused by parainfluenza virus and reduces granulocytic inflammation induced by ischemia-reperfusion. We investigated the effects of L-arginine on a murine model of allergic asthma that included airway hyperresponsiveness, eosinophilic inflammation and expression of interleukin (IL)-5 in the lung. The mice received drinking water with or without L-arginine for 9 weeks. Histologic evaluation and cellular profiles in bronchoalveolar lavage fluid showed that p.o. administration of L-arginine (72 micromol/kg/day) significantly enhanced eosinophilic airway inflammation and goblet cell proliferation that were associated with intratracheal instillation of ovalbumin. L-Arginine also increased protein levels of IL-5 and IL-2 in supernatants from the lung exposed to ovalbumin. The number of eosinophils in bronchoalveolar lavage fluid correlated significantly with the expression of IL-5. L-Arginine did not reverse ovalbumin-associated airway hyperresponsiveness to inhaled ACh. These results suggest that p.o. administration of L-arginine aggravates allergen-induced eosinophilic airway inflammation via expression of IL-5, and in this model it does not show therapeutic efficacy against airway hyperresponsiveness associated with allergen exposure. Oral administration of L-arginine, the precursor of nitric oxide, may not be an effective intervention in allergic asthma.

Inhalation of diesel exhaust enhances allergen-related eosinophil recruitment and airway hyperresponsiveness in mice

We have previously shown that intratracheal instillation of suspension of diesel exhaust particles enhances allergen-related eosinophilic airway inflammation, airway hyperresponsiveness, and local expression of interleukin (IL)-5 and granulocyte macrophage-colony stimulating factor (GM-CSF) in mice. The present study was designed to elucidate the effects of daily inhalation of diesel exhaust (DE) on the allergen-related respiratory disease. ICR mice were exposed for 40 weeks to clean air or DE at a soot concentration of 0.3, 1.0, or 3.0 mg/m3 with aerosol allergen challenges (1% ovalbumin in isotonic saline for 6 min) at 3-week intervals during the last 24 weeks of exposures. Exposure to DE enhanced allergen-related eosinophil recruitment to the submucosal layers of the airways and to the bronchoalveolar space, and increased protein levels of GM-CSF and IL-5 in the lung in a dose-dependent manner compared to exposure to clean air. There were strong correlations between the number of eosinophils in bronchoalveolar lavage (BAL) fluid and IL-5 concentrations in BAL supernatants and lung tissue supernatants. In addition, the increases in eosinophil recruitment and local cytokine expression were accompanied by goblet cell proliferation in the bronchial epithelium and airway hyperresponsiveness to inhaled acetylcholine. In contrast, the control mice exposed for 40 weeks to clean air or DE at a soot concentration of 0.3, 1.0, or 3.0 mg/m3 without allergen provocation showed no eosinophil recruitment to the submucosal layers of the airways nor to the bronchoalveolar space and few goblet cells in the bronchial epithelium. The present study provides experimental evidence that daily inhalation of DE can enhance allergen-related respiratory diseases such as allergic asthma. This effect may be mediated by the enhanced local expression of IL-5 and GM-CSF. Increased ambient levels of DE may be implicated in the increasing prevalence of bronchial asthma in recent years.

Diesel exhaust enhances allergic airway inflammation and hyperresponsiveness in mice

We previously reported that the intratracheal instillation of diesel exhaust particles enhances allergic airway inflammation and hyperresponsiveness in mice. However, it is not known whether the effects of such instillation differ from those obtained with the daily inhalation of diesel exhaust. We therefore examined whether the inhalation of diesel exhaust would also enhance allergic reactions. Mice were exposed to diesel exhaust or clean air for 5 wk. After the first week, the animals were sensitized to ovalbumin by intraperitoneal injection. At the end of the exposure period, they underwent an ovalbumin challenge. Control animals received saline instead of ovalbumin. Independently of ovalbumin sensitization, diesel exhaust caused an increase in the numbers of neutrophils and macrophages in bronchoalveolar lavage fluid, whereas a significant increase in eosinophil numbers occurred only after antigen challenge combined with diesel exhaust exposure. Furthermore, ovalbumin alone caused an increase in eosinophil numbers in lung tissue, and this was enhanced by diesel exhaust. Exposure to diesel exhaust combined with ovalbumin sensitization, but not diesel exhaust inhalation alone, enhanced the number of goblet cells in lung tissue, respiratory resistance, production of ovalbumin-specific immunoglobulin E and G1 in the serum, and expression of interleukin-5 in lung tissue.

Murine strain differences in airway inflammation caused by diesel exhaust particles

To elucidate whether immunoglobulin (Ig) E or IgG are involved in the murine asthma model, we compared the pathogenic features of mice that were high IgG responders (C3H/He) with mice that were high IgE responders (BALB/c) after intratracheal instillation of diesel exhaust particles (DEP) and ovalbumin sensitization. Both mouse strains received DEP intratracheally once a week for 5 weeks. After the second injection of DEP, ovalbumin and aluminium hydroxide were injected intraperitoneally. After the last DEP administration, the mice were challenged by exposure to an aerosol of ovalbumin. DEP caused increased IgG1 production and airway hyperresponsiveness after ovalbumin sensitization in C3H/He mice, although IgE production did not change in either strain. Furthermore, in C3H/He mice, the number of eosinophils and goblet cells in the bronchial epithelium, and the expression of interleukin-5 and interleukin-2 were increased by DEP and ovalbumin treatments. In contrast, the pathogenic changes in BALB/c mice were weak, even though the same protocol was used. In conclusion, murine strain differences in response to air pollutants and allergens seem to be related to antigen-specific immunoglobulin G1 production and cytokine expression in the lungs.

Differential requirements for conserved E2 binding sites in the life cycle of oncogenic human papillomavirus type 31

Human papillomavirus (HPV) E2 proteins regulate viral replication by binding to sites in the upstream regulatory region (URR) and by complex formation with the E1 origin recognition protein. In the genital HPV types, the distribution and location of four E2 binding sites (BS1 to BS4) which flank a single E1 binding site are highly conserved. We have examined the roles of these four E2 sites in the viral life cycle of HPV type 31 (HPV31) by using recently developed methods for the biosynthesis of papillomaviruses from transfected DNA templates (M. G. Frattini et al., Proc. Natl. Acad. Sci. USA 93:3062-3067, 1996). In transient assays, no single site was found to be necessary for replication, and mutation of the early promoter-proximal site (BS4) led to a fourfold increase in replication. Cotransfection of the HPV31 wild-type (HPV-wt) and mutant genomes with expression vectors revealed that E1 stimulated replication of HPV31-wt as well as the HPV31-BS1, -BS2, and -BS3 mutants. In contrast, increased expression of E2 decreased replication of these genomes. Replication of the HPV31-BS4 mutant genome was not further increased by cotransfection of E1 expression vectors but was stimulated by E2 coexpression. In stably transfected normal human keratinocytes, mutation of either BS1, BS3, or BS4 resulted in integration of viral genomes into host chromosomes. In contrast, mutation of BS2 had no effect on stable maintenance of episomes or copy number. Following growth of stably transfected lines in organotypic raft cultures, the differentiation-dependent induction of late gene expression and amplification of viral DNA of the BS2 mutant was found to be similar to that of HPV31-wt. We were unable to find a role for BS2 in our assays for viral functions. We conclude that at least three of the four E2 binding sites in the URRs of HPVs are essential for the productive viral life cycle. The specific arrangement of E2 binding sites within the URR appears to be more important for viral replication than merely the number of sites.

Induction of human papillomavirus type 18 late gene expression and genomic amplification in organotypic cultures from transfected DNA templates

The genetic analysis of human papillomavirus (HPV) functions during the vegetative viral life cycle is dependent upon the ability to generate human keratinocyte cell lines which maintain episomal copies of transfected viral genomes. We have previously demonstrated that lipofection of normal human foreskin keratinocytes with recircularized cloned HPV-31 genomic sequences resulted in a high frequency of cell lines which maintained viral genomes as extrachromosomal elements (M.G. Frattini, H. Lim, and L.A. Laimins, Proc. Natl. Acad. Sci. USA 93:3062-3067, 1996). Following the growth of these cell lines in organotypic (raft) cultures, the differentiation-dependent expression of viral late genes, the amplification of viral genomes, and virion biosynthesis were observed. In the present study, we demonstrate that these methodologies are not restricted to HPV-31 but are applicable to other HPV types, including the oncogenic HPV-18. HPV-18 genomes were purified from bacterial vector sequences, religated, and transfected into normal human foreskin keratinocytes together with a neomycin-selectable marker. Following drug selection, resistant cells were expanded and examined for the state of the viral DNA. All cell lines examined were found to contain approximately 100 to 200 episomal copies of HPV-18 DNA per cell. Growth of these cell lines in raft cultures resulted in the differentiation-dependent expression of the E1 [symbol: see text] E4 and L1 capsid genes. In addition, viral genome amplification was observed in suprabasal cells following DNA in situ hybridization analysis of differentiated raft cultures. The induction of these late viral functions has previously been shown to be directly associated with differentiation-dependent virion biosynthesis. Our studies indicate the ability to perform a detailed genetic analysis of the various phases of the viral life cycle, including control of the differentiation-dependent late viral functions, using a second oncogenic HPV type.

Abrogation of a mitotic checkpoint by E2 proteins from oncogenic human papillomaviruses correlates with increased turnover of the p53 tumor suppressor protein

Human papillomavirus (HPV) E2 and E1 proteins are required for the replication of viral genomes in vivo. We have examined the effects of increasing the level of E2 on viral and cellular replication using recombinant adenoviruses. Infection of cells which maintain HPV 31 DNA episomally with E2 recombinant adenoviruses resulted in a 5-fold increase in genome copy number as well as an S phase arrest allowing for the continued replication of cellular DNA. Similar effects on cell cycle progression were seen following infection of normal human foreskin keratinocytes, the natural host cell. The DNA content of these cells increased beyond 4N indicating that multiple rounds of replication had occurred without an intervening mitotic event. In addition, increased cyclin A and E associated kinase activity was observed, while no change was detected in cyclin B associated kinase activity or in the activation state of cdc2 kinase. Interestingly, the levels of the p53 tumor suppresser protein were dramatically reduced through a post-transcriptional mechanism following infection. These data suggest a role for E2 in regulating viral and cellular replication by abrogation of a mitotic checkpoint, which is, at least in part, controlled by p53.

In vitro synthesis of oncogenic human papillomaviruses requires episomal genomes for differentiation-dependent late expression

Human papillomavirus (HPV) types 16, 18, 31, and 51 are the etiologic agents of many anogenital cancers including those of the cervix. These "high risk" HPVs specifically target genital squamous epithelia, and their lytic life cycle is closely linked to epithelial differentiation. We have developed a genetic assay for HPV functions during pathogenesis using recircularized cloned HPV 31 genomes that were transfected together with a drug resistance marker into monolayer cultures of normal human foreskin keratinocytes, the natural host cell. After drug selection, cell lines were isolated that stably maintained HPV 31 DNA as episomes and underwent terminal differentiation when grown in organotypic raft cultures. In differentiated rafts, the expression of late viral genes, amplification of viral DNA, and production of viral particles were detected in suprabasal cells. This demonstrated the ability to synthesize HPV 31 virions from transfected DNA templates and allowed an examination of HPV functions during the vegetative viral life cycle. We then used this system to investigate whether an episomal genome was required for the induction of late viral gene expression. When an HPV 31 genome (31E1*) containing a missense mutation in the E1 open reading frame was transfected into normal human keratinocytes, the mutant viral sequences were found to integrate into the host cell chromosomal DNA with both early and late regions intact. While high levels of early viral gene transcription were observed, no late gene expression was detected in rafts of cell lines containing the mutant viral genome despite evidence of terminal differentiation. Therefore, the induction of late viral gene expression required that the viral genomes be maintained as extrachromosomal elements, and terminal differentiation alone was not sufficient. These studies provide the basis for a detailed examination of HPV functions during viral pathogenesis.

Human papillomavirus type 31b late gene expression is regulated through protein kinase C-mediated changes in RNA processing

Expression of the human papillomavirus (HPV) capsid genes, L1 and L2, as well as amplification of viral DNA and virion assembly occur in the terminally differentiated layers of infected stratified squamous epithelium in vivo. These processes can be duplicated in the laboratory through the use of organotypic or raft cultures. When CIN612 cells, which contain episomal copies of the high-risk HPV type 31b, are allowed to differentiate in raft cultures, the expression of transcripts encoding the early genes E1--E4 and E5 is induced. These transcripts are initiated at the differentiation-dependent P742 promoter located in the middle of the E7 open reading frame. Exposure of raft cultures to activators of protein kinase C, such as phorbol esters, results in the further induction of late gene expression as well as virion assembly. In this study, we have investigated the mechanism by which activators of protein kinase C induce late gene expression. The major L1 transcript was found to be encoded by a bicistronic E1--E4, L1 RNA which initiated at the differentiation-dependent promoter P742. Additional low-level expression of L1-containing RNAs was also observed from the early-region promoter, P97. The major L2 transcripts were found to be encoded by E1--E4, E5, L2, L1 RNAs which were also initiated in the early region, probably at the differentiation-specific promoter P742. While early and late RNAs were found to be expressed from the same promoter, they differed in utilization of splicing and polyadenylation sites. Raft cultures treated with activators of protein kinase C induced expression of late genes, but no change in the abundance of early RNAs initiated at the P742 promoter was observed. Thus, the increase in late gene expression was likely due to changes in RNA processing or stabilization rather than an increase in the rate of transcription from P742. Regulation of HPV late gene expression therefore occurs at two levels: differentiation-dependent induction of the P742 promoter, which can be mimicked in vitro by growth in raft cultures, and posttranscriptional changes that can be induced by activation of protein kinase C. These posttranscriptional changes may occur through inactivation or down-regulation of splicing factors which inhibit use of the late region polyadenylation site, resulting in increased stability of late region transcripts.

Simple and sensitive laser-induced fluorescence detection for capillary electrophoresis and its application to protein separation

A low-cost and highly sensitive laser-induced fluorescence detector for on-column detection systems was constructed and its applications were demonstrated in protein separation by capillary electrophoresis. The limit of detection (LOD) at a signal-to-noise ratio of 2 for Lissamine 20 was about 1.4 x 10(-21) mole at 10 nL sample injection and the relative standard deviation (RSD) for 1.5 x 10(-11) M of Lissamine 20 solution was about 15%. These values are comparable to or even better than those reported using a similar on-column detection system. This sensitive LIF detection was applied for the study of tryptic digestion of insulin and for urinary protein profiling.

Modulation of cytochrome P-450 induction by long-term food restriction in male rats

The influence of food restriction (FR) on the induction of liver microsomal cytochrome P-450 (P-450) was examined in rats, FR by 40% for 6 weeks caused increase in the levels of P-450, cytochrome b5 (b5), NADPH P-450 reductase, NADH b5 reductase, P-450 dependent testosterone 6 beta-, 16 alpha- and 16 beta-hydroxylases (P < 0.05). Treatment of 3-methylcholanthrene (MC) to food restricted rats (FR rats) induced more P-450, but phenobarbital (PB) induced it less. MC-inducible P-450 from FR rats did not increase its specific ethoxycoumarin O-deethylase activity but it increased testosterone 2 alpha-hydroxylase activity, and the maximum absorption of its CO complex was shifted from 448 nm to 450 nm. PB-inducible P-450 showed less increase in the activities of its specific benzphetamine N-demethylase and it rather significantly decreased testosterone 16 alpha-hydroxylase activity (P < 0.05). These results indicate that the drugs did not induce their unique types of P-450 in FR rats. Such alterations in P-450 induction in FR rats seem to be closely related to the level of P-450 and its related components enhanced by FR, and it could result in modulation of mixed function oxidase system.

Effect of subchronic administration of antioxidants against cigarette smoke exposure in rats

Effects of subchronic administration of antioxidants against pulmonary damage mediated by cigarette smoke were investigated in rats. Rats were continuously received ascorbic acid, N-acetylcysteine and ginseng extract together drinking water from day 25 after birth. After 30 days of antioxidant supplementation, rats were exposed to cigarette smoke generated from six cigarettes (11 mg tar) for 20 min per day throughout 30 days, and then several biochemical markers related to the redox status in vivo were analyzed in the respiratory system. The cigarette smoke induced mild histological changes in trachea and lungs. The activity of superoxide dismutase (SOD) in the lung was significantly increased, and catalase and glutathione peroxidase activities were increased less than SOD, but total sulfhydryl compounds (Total-SH) content was decreased by cigarette smoking. In spite of the increase in activities of antioxidant enzymes, the inhibitory capacity of lung preparations on in vitro lipid peroxidation using ox brain homogenates was decreased and the change in the capacity was not related to the changes of these intracellular enzymes activities, but with the content of Total-SH. On the other hand, the content of thiobarbituric acid reactive substances and the ratio of elastase to anti-protease in the lung homogenates were significantly increased. Supplementation of antioxidants, however, effectively attenuated all of such alterations induced by cigarette smoke. These results indicate that although cigarette smoking induces antioxidant enzymes in the lung as a self defense mechanism, it seems to be not sufficient to protect the pulmonary system, and that chronic antioxidant feeding could be effective to reduce pulmonary damage induced by free radicals.