[Evaluation of the efficacy of urine-based lipoarabinomannan antigen test in the diagnosis of pulmonary tuberculosis]

Objective: To analyze the diagnostic efficacy of urinary lipoarabinomannan (LAM) antigen detection method in tuberculosis patients, and to provide an experimental basis for the clinical application of urinary LAM kit in China. Methods: From March to May 2023, 228 patients with lung diseases [134 male, 94 female, age 20-82 (44.8±16.7) years] were prospectively collected in Beijing Chest Hospital, Capital Medical University, including 143 pulmonary tuberculosis patients and 85 non-tuberculosis patients. Urine and sputum samples from patients were collected for traditional etiological detection and urinary LAM antigen detection. The screening results of each positive detection combination were analyzed, and the difference analysis and regression analysis were performed. Results: The detection sensitivity and specificity of the urinary LAM kit were 46.2% (95%CI: 37.9%-54.7%) and 96.5% (95%CI: 89.3%-99.1%), respectively, with an overall coincidence rate of 64.9%. The detection rate of LAM antigen detection and GeneXpert MTB/RIF (Xpert) combined (60.8%, 87/143) was significantly higher than that of Xpert alone (49.7%, 71/143), and the difference was statistically significant (P<0.05). The results of risk factor analysis showed that the risk of negative urinary LAM antigen test results increased significantly as the bacterial load decreased. Conclusions: Urine LAM antigen detection method has a high specificity and can be combined with traditional methods to effectively improve the detection rate. Urinary LAM antigen detection method still has limitations, such as the influence of bacterial load and the inability to distinguish nontuberculosis mycobacteria samples, which needs further experimental verification.

Molecular mechanisms of MCM3AP-AS1 targeted the regulation of miR-708-5p on cell proliferation and apoptosis in gastric cancer cells

The article "Molecular mechanisms of MCM3AP-AS1 targeted the regulation of miR-708-5p on cell proliferation and apoptosis in gastric cancer cells, by H. Wang, T. Xu, L. Wu, H.-L. Xu, R.-M. Liu, published in Eur Rev Med Pharmacol Sci 2020; 24 (5): 2452-2461-DOI: 10.26355/eurrev_202003_20512-PMID: 32196596" has been withdrawn from the authors due to the discovery of new results. The authors decided to improve them further. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/20512.

Molecular mechanisms of MCM3AP-AS1 targeted the regulation of miR-708-5p on cell proliferation and apoptosis in gastric cancer cells

OBJECTIVE

Gastric cancer (GC) is a common malignancy of the digestive tract. Accumulated studies proved that long non-coding RNA MCM3AP-AS1 (MCM3AP-AS1) modified the mechanism of the progression of GC. However, the molecular mechanism is still greater elusive. Hence, we aimed to explore the molecular mechanism of MCM3AP-AS1 targeting the regulation of microRNA-708-5p on cell proliferation and apoptosis in GC cells.

MATERIALS AND METHODS

The expression levels of MCM3AP-AS1 (MCM3AP antisense RNA 1) in gastric mucosal cells GES-1 and gastric cancer cell lines of MGc-803 and SGC-7901 cells were detected by qRT-PCR. Moreover, the protein levels of Cyclin D1, P21, Bax and Bcl-2 in MGc-803 and SGC-7901 cells after transfection were detected by Western blot. MTT assay was performed to detect cell proliferation and flow cytometry was carried out to determine GC cell apoptosis in vitro. In the endpoint, the targeting relationship between MCM3AP-AS1 and microRNA-708-5p was detected by Dual-Luciferase reporter assay.

RESULTS

The level of MCM3AP-AS1 was significantly promoted in GC cell lines. Knockdown of MCM3AP-AS1 curbed cell proliferation and enhanced apoptosis in MGc-803 and SGC-7901 cells. Furthermore, the effect of the downregulation of MCM3AP-AS1 on cell proliferation and apoptosis was reversed by knockdown of miR-708-5p, which was targeted by MCM3AP-AS1 in vitro.

CONCLUSIONS

MCM3AP-AS1 regulates the proliferation and apoptosis of gastric cancer cells by targeting the expression of microRNA-708-5p. The study may be useful to the therapy target of human GC.

Phase transitions in the classical exchange-anisotropic Kitaev-Heisenberg model

The Kitaev model on the honeycomb lattice has been receiving substantial attention due to the discovery of quantum spin liquid state associated with this model. Consequently, its classical partners such as the Kitaev-Heisenberg (KH) model and associated phase transitions become concerned. Specifically, an intermediate Kosterlitz-Thouless (KT) phase engaged in the transition from the high-temperature (T) disordered state to the low-T sixfold degenerate state is predicted in the isotropic KH model [Phys. Rev. Lett. 109, 187201 (2012)10.1103/PhysRevLett.109.187201], but so far no sufficient experimental proof has been reported. In this work, we consider an essential extension of this KH model on the honeycomb lattice by including the Kitaev exchange anisotropy that is non-negligible in realistic materials. The associated phase transitions are thus investigated using the Monte Carlo simulations. It is found that such an anisotropy will result in a degradation of the sixfold degeneracy of the ground state in the isotropic KH model down to the fourfold or twofold degenerate ground state, and the finite-T phase transitions will also be modified remarkably. Interestingly, the intermediate KT phase can be suppressed by this Kitaev exchange anisotropy. This work thus provides a more realistic description of the physics ingredient with the KH model and presents a possible explanation on absence of the intermediate phase in real materials where the Kitaev exchange anisotropy can be more or less available.

Synthetic chimeric nucleases function for efficient genome editing

CRISPR-Cas systems have revolutionized genome editing across a broad range of biotechnological endeavors. Many CRISPR-Cas nucleases have been identified and engineered for improved capabilities. Given the modular structure of such enzymes, we hypothesized that engineering chimeric sequences would generate non-natural variants that span the kinetic parameter landscape, and thus provide for the rapid selection of nucleases fit for a particular editing system. Here, we design a chimeric Cas12a-type library with approximately 560 synthetic chimeras, and select several functional variants. We demonstrate that certain nuclease domains can be recombined across distantly related nuclease templates to produce variants that function in bacteria, yeast, and human cell lines. We further characterize selected chimeric nucleases and find that they have different protospacer adjacent motif (PAM) preferences and the M44 chimera has higher specificity relative to wild-type (WT) sequences. This demonstration opens up the possibility of generating nuclease sequences with implications across biotechnology.

Magnetic impurity doping induced spin-glass state and short-range zigzag order in the honeycomb iridate Na2IrO3

Based on the modified Heisenberg-Kitaev model, the effects of magnetic substitution on the magnetic properties of the honeycomb-lattice iridate [Formula: see text] [Formula: see text] are studied using Monte Carlo simulations. It is observed that the long-range zigzag state of the original system is rather fragile and can be replaced by a spin-glass state even for small substitution, well consistent with the experimental observation in Ru-substituted samples (Mehlawat et al 2015 Phys. Rev. B 92 134412). Both the disordered Heisenberg and Kitaev interactions caused by the magnetic ion-doping are suggested to be responsible for the magnetic phase transitions in the system. More interestingly, a short-range zigzag order is suggested to survive above the freezing temperature even at high magnetic impurity doping levels.

Ashkin-Teller criticality and weak first-order behavior of the phase transition to a fourfold degenerate state in two-dimensional frustrated Ising antiferromagnets

We study the thermal phase transition of the fourfold degenerate phases (the plaquette and single-stripe states) in the two-dimensional frustrated Ising model on the Shastry-Sutherland lattice using Monte Carlo simulations. The critical Ashkin-Teller-like behavior is identified both in the plaquette phase region and the single-stripe phase region. The four-state Potts critical end points differentiating the continuous transitions from the first-order ones are estimated based on finite-size-scaling analyses. Furthermore, a similar behavior of the transition to the fourfold single-stripe phase is also observed in the anisotropic triangular Ising model. Thus, this work clearly demonstrates that the transitions to the fourfold degenerate states of two-dimensional Ising antiferromagnets exhibit similar transition behavior.

[Chronic hypoxia increases intracellular Ca(2+) concentration and augments proliferation by enhancing store-operated Ca(2+) entry in pulmonary arterial smooth muscle cells]

OBJECTIVE

To determine whether store-operated Ca(2+) entry (SOCE) is involved in chronic hypoxia-induced alteration of intracellular Ca(2+) concentration ([Ca(2+) ]i) and proliferation in pulmonary arterial smooth muscle cells (PASMC).

METHODS

Rat PASMCs were cultured and treated in normoxia (21%O2) or hypoxia (4%O2) condition. The proliferation of PASMC was detected by cell counting kit-8 (CCK-8) assay. [Ca(2+) ]i, SOCE and the effects of store-operated Ca(2+) channel (SOCC) inhibitors, SKF96365 and NiCl2, on SOCE in hypoxic PASMCs were tested by InCyte [Ca(2+) ]i measurement system.

RESULTS

Hypoxia for 24-60 h augmented PASMC proliferation (1.12±0.09 vs 0.71±0.05, P<0.05) and [Ca(2+) ]i [(214.8 ± 20.4) nmol/L vs (115.2±13.2) nmol/L, P<0.05] in a time-dependent manner with the maximum effect at 60 h. Perfusion of Ca(2+) -free Krebs solution containing nifedipine (5 μmol/L), cyclopiazonic acid (CPA, 10 μmol/L) in PASMCs caused a small transient increase of [Ca(2+) ]i with peak [Ca(2+) ]i (113.3±49.3) nmol/L.Chronic hypoxia (4% O2, 60 h) enhanced [Ca(2+) ]i level with peak value of (193.2±22.7) nmol/L (P<0.05) in PASMC.After restoration of extracellular Ca(2+) , CPA caused marked increase of [Ca(2+) ]i with peak value of (328.0 ±56.7) nmol/L.Chronic hypoxia strengthened CPA-induced increase of [Ca(2+) ]i with peak value of (526.0±33.7) nmol/L (P<0.05) in PASMCs.Either SKF96365 50 μmol/L or NiCl2 500 μmol/L distinctly attenuated CPA-induced enhancement of [Ca(2+) ]i, the peak value of which dropped from (526.0±33.7) nmol/L to (170.4±26.4) nmol/L (P<0.05) or (177.4±45.9) nmol/L (P<0.05) respectively.

CONCLUSION

Chronic hypoxia boosts the release of Ca(2+) from sarcoplasmic reticulum and promotes the activity of SOCC and SOCE, leading to [Ca(2+) ]i elevation and proliferation of rat PASMCs.

Role of further-neighbor interactions in modulating the critical behavior of the Ising model with frustration

In this work, we investigate the phase transitions and critical behaviors of the frustrated J(1)-J(2)-J(3) Ising model on the square lattice using Monte Carlo simulations, and particular attention goes to the effect of the second-next-nearest-neighbor interaction J(3) on the phase transition from a disordered state to the single stripe antiferromagnetic state. A continuous Ashkin-Teller-like transition behavior in a certain range of J(3) is identified, while the four-state Potts-critical end point [J(3)/J(1)](C) is estimated based on the analytic method reported in earlier work [Jin, Sen, and Sandvik, Phys. Rev. Lett. 108, 045702 (2012)]. It is suggested that the interaction J(3) can tune the transition temperature and in turn modulate the critical behaviors of the frustrated model. Furthermore, it is revealed that an antiferromagnetic J(3) can stabilize the staggered dimer state via a phase transition of strong first-order character.

Inadequate values from an interferon-gamma release assay for smear-negative tuberculosis in a high-burden setting

OBJECTIVE

To examine the usefulness of an interferon-gamma release assay (IGRA) for the diagnosis of smear-negative tuberculosis (TB) in China.

DESIGN

A total of 624 patients with presumed pulmonary TB were enrolled prospectively and categorised as smear-negative TB, smear-positive TB or no TB. All patients were tested using T-SPOT.TB.

RESULTS

Both the smear-negative and smear-positive TB groups had significantly more spot-forming cells (SFCs) than the no TB group (all P < 0.001), while the smear-negative group had fewer SFCs than the smear-positive TB group (P < 0.001). The specificity of T-SPOT.TB was 60.4% (95%CI 53.4-67.1). The sensitivities of T-SPOT.TB in the smear-negative and smear-positive TB groups were respectively 81.4% (95%CI 75.7-86.0) and 93.2% (95%CI 87.6-96.4). The sensitivity in the smear-negative TB group was much lower than that in the smear-positive TB (P < 0.05).

CONCLUSIONS

The sensitivity of T-SPOT.TB was lower due the paucibacillary nature of the samples, and the specificity was lower due to the high prevalence of latent tuberculous infection in the smear-negative TB patients. The T-SPOT.TB test should only be used as a supplementary test and not as a single test to rule in or rule out smear-negative TB.

Comparison of effects of devascularization versus shunt on patients with portal hypertension: a meta-analysis

OBJECTIVE

To systematically evaluate the effectiveness of devascularization and shunt on patients with portal hypertension.

METHODS

Relevant studies compared devascularization and shunt for the treatment of portal hypertension were identified searching the PubMed, Embase, Elsevier, CNKI (China National Knowledge Infrastructure) database and Cochrane Trial Register searches until December 2013. Data of interest for devascularization and shunt including postoperative recurrent bleeding, postoperative hepatic encephalopathy,ascites, operative mortality rate, and long term survival rate were subjected to meta-analysis.

RESULTS

Eleven studies were included in the study, the results of the meta-analysis showed that all eleven clinical studies demonstrated a significantly higher postoperative recurrent bleeding rate with devascularization group than with shunt group (Odds Ratio =2.14, 95% CI =(1.42, 3.21), P = 0.0003),the rate of hepatic encephalopathy in the devascularization group was significantly lower compared with the shunt group (Odds Ratio =0.56, 95% CI =(0.38, 0.82), P = 0.003); Our meta-analysis of three clinical studies revealed that the reduction of ascites in the devascularization group was significantly less than the shunt groups (Odds Ratio =0.48, 95% CI =(0.26, 0.89), P = 0.02), the operative mortality rate was not significantly different between the devascularization group than for shunt group (Odds Ratio =1.54, 95% CI = (0.91,2.63), P = 0.11). And the long-term survival rate was not significantly different between the devascularization and shunt groups (Odds=1.13, ratio, 95% CI =(0.64, 1.99), P = 0.68).

CONCLUSIONS

Devascularization and shunt have different advantages and disadvantages respectively which reflected in postoperative complications and long term survival rate.

Trend of dissolved inorganic nitrogen at stations downstream from the Three-Gorges Dam of Yangtze River

The TRAMO/SEATS program, combined with the Hodrick-Prescott (HP) filter, was used to detect trends and potential change points in time series of dissolved inorganic nitrogen (DIN) at three stations along the Yangtze River. The trend components were extracted, and two change points were successfully detected. The components revealed that DIN has been increasing at all the stations since the 1990s, although variations exist. Changes visible before 2002 illustrate the differences in agriculture development among regions upstream from the stations. The Three-Gorges Dam (TGD), which began to impound in 2003, led to years of different trends. The DIN concentration, which had been trending upward prior to that date, began a slightly downward trend because of NH4(+) depletion. Readings at the Yichang station revealed this trend most strongly; those at the Hankou station less so. The Datong station was far enough away from the TGD so that no obvious effects were seen.

Oxidant-induced regulation of glutathione synthesis

This unit describes protocols for characterizing the expression of two glutathione biosynthesis enzymes: gamma-glutamylcysteine synthase (GCS) and gamma-glutamyl transpeptidase (GGT) in response to oxidants. GCS catalyzes the first and rate-limiting step of glutathione synthesis, while GGT degrades extracellular glutathione (GSH) to provide the amino acids required for intracellular synthesis of GSH. Northern blot hybridization is used to quantitatively assess the mRNAs for the two enzymes in response to oxidant. Nuclear run-on is used to determine the rate of transcription.

Transfer of Ser7 phosphorylated CENP-A from centromere to midbody during mitosis in MCF-7 cells

Serine 7 of centromere protein A (CENP-A) is a very important mitosis-specific phosphorylation site. In this study, we demonstrate the subcellular distribution of Ser7 phosphorylated CENP-A during mitosis in MCF-7 cells. The Ser7 phosphorylation of CENP-A was observed beginning at prophase at centromeres. Upon progression of mitosis, the fluorescence signals emerged in the central region of the metaphase plate and were maintained until anaphase at centromeres. At late anaphase, the fluorescence signals moved to the midzone gradually and transferred from the centromere to the midbody completely at telophase. They were compacted into the centre of the midbody in a thin cylinder consisting of a sandglass-like "mitotic machine" with microtubules and condensed chromosome. We also found that Ser10 phosphorylated H3 and Thr11 phosphorylated H3 were co-localized at the midbody in two bell-like symmetrical bodies with Ser7 phosphorylated CENP-A during the terminal stage of cytokinesis. Midbody isolation and immunoblotting experiments also indicated that Ser7 phosphorylated CENP-A are components of the midbody. These findings suggest that Ser7 phosphorylated CENP-A acts as a chromosomal passenger protein and may play an important role in cytokinesis.

Oxidative stress and glutathione in TGF-beta-mediated fibrogenesis

Transforming growth factor beta (TGF-beta) is the most potent and ubiquitous profibrogenic cytokine, and its expression is increased in almost all the fibrotic diseases and in experimental fibrosis models. TGF-beta increases reactive oxygen species production and decreases the concentration of glutathione (GSH), the most abundant intracellular free thiol and an important antioxidant, which mediates many of the fibrogenic effects of TGF-beta in various types of cells. A decreased GSH concentration is also observed in human fibrotic diseases and in experimental fibrosis models. Although the biological significance of GSH depletion in the development of fibrosis remains obscure, GSH and N-acetylcysteine, a precursor of GSH, have been used in clinics for the treatment of fibrotic diseases. This review summarizes recent findings in the field to address the potential mechanism whereby oxidative stress mediates fibrogenesis induced by TGF-beta and the potential therapeutic value of antioxidant treatment in fibrotic diseases.

Knockout of plasminogen activator inhibitor 1 gene reduces amyloid beta peptide burden in a mouse model of Alzheimer's disease

Accumulation of amyloid beta peptide (Aβ) in the brain is a pathological hallmark of Alzheimer's disease (AD); the underlying mechanism, however, is not well understood. In this study, we show that expression of plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue type and urokinase type plasminogen activators (tPA and uPA), increases with age in the brain of wild type and Aβ precursor protein-presenilin 1 (APP/PS1) transgenic mice as well as in AD patients. Most importantly, we show that knocking out the PAI-1 gene dramatically reduces Aβ burden in the brain of APP/PS1 mice but has no effect on the levels of full-length APP, alpha or beta C-terminal fragments. Furthermore, we show that knocking out the PAI-1 gene leads to increases in the activities of tPA and plasmin, and the plasmin activity inversely correlates with the amounts of SDS insoluble Aβ40 and Aβ42. Together, these data suggest that increased PAI-1 expression/activity contributes importantly to Aβ accumulation during aging and in AD probably by inhibiting plasminogen activation and thus Aβ degradation.

Dynamic distribution of Thr3-phosphorylated histone H3 in CHO cells in mitosis

The phosphorylation of histone H3 at Ser10, Ser28, Thr11 and Thr3 of the amino terminal has been proved related to mitosis of the mammalian cells. However, the function of the Thr3 phosphorylation of H3 remains unclear. In this study, indirect immunofluorescence labelling and laser confocal microscopy were used to examine the cellular dynamic distribution of Thr3-phosphorylated H3 at mitosis in CHO cells. The results showed that the Thr3 phosphorylation began at early prophase and spread throughout the chromosomes at late prophase. At metaphase, most of the Thr3-phosphorylated H3 was distributed along the entire chromosomal arms and maintained until early anaphase. During late anaphase and telophase, the fluorescent signal of Thr3-phosphorylated H3 disappeared from chromosomes. There was a precise spatial and temporal correlation between H3 phosphorylation of Thr3 and stages of chromatin condensation. The timing of Thr3 phosphorylation and dephosphorylation in mitosis were similar to that reported for Thr11 phosphorylation of H3. The Thr3-phosphorylated H3 localized along the arms of chromosomes during metaphase and early anaphase. It was different from the Ser10-phosphorylated H3, which localized at telomere regions, and Thr11-phosphorylated H3, which localized at centromeres. The results suggest that the Thr3 phosphorylation of histone H3 may play a specific role, which is different from Ser10 phosphorylation and Thr11 phosphorylation in mitosis.

Spatial analysis and eutrophication assessment for chlorophyll a in Taihu Lake

Spatial structure analysis and kriging analysis have been identified to be useful tools in illustrating the spatial patterns of variables. Taihu Lake is one of the largest fresh water lakes in China, and has suffered serious eutrophication in recent years due to the rapid economic development and growing environmental pollution in the Taihu Catchment. In this paper, spatial structural analysis, kriging interpolation and eutrophication assessment were carried out for chlorophyll a in the lake. Studies show that spherical model could be applied to fit all experimental variograms. Positive nuggets were observed for three directions except NE-SW direction. The variograms show some anisotropy with anisotropic ratio falling within 1.76. The spatial structural patterns of chlorophyll a in the lake were affected by factors such as distribution of pollution sources, water flow and wind. Two-dimensional ordinary block kriging was applied for interpolation process. An eutrophication assessment map was also made based on a water-quality evaluation standard. Results show that the content of chlorophyll a in Taihu Lake was quite high. The whole lake has suffered serious eutrophication. However, the eutrophic situation varied in space. Higher contents of chlorophyll a appeared mainly in the northern part of the lake.

Medium scale spatial structures of Polycyclic Aromatic Hydrocarbons in the topsoil of Tianjin area

The spatial distribution patterns of Polycyclic Aromatic Hydrocarbons (PAHs) in soil are important to regional environmental assessment. In this paper, the spatial structural features of sixteen prior PAH compounds in the topsoil of Tianjin area, as well as soil properties, were studied. Results shown that medium scale spatial autocorrelations were well revealed. Spherical models with sills could be used to fit all experimental variograms. The spatial structures of PAHs contents demonstrated significant anisotropy. Air precipitation caused by the combustion of coal was the key factor in the formation of the spatial structural patterns of PAHs in the topsoil of Tianjin area.

Development of a topical suspension containing three active ingredients

The objective of this study was to develop a topical suspension that contains sarafloxacin hydrochloride (1 mg/mL), triamcinolone acetonide (1 mg/mL), and clotrimazole (10 mg/mL), and is stable at room temperature (15-28 degrees C) for clinical usage. Due to the difference in the physicochemical properties and chemical stability profiles of these three active ingredients, it is a challenge to develop a stable suspension formulation containing these three drugs. In this study, the stability of these drugs in different buffer solutions was determined under different accelerated isothermal conditions. The Arrhenius equation was subsequently utilized to predict the room-temperature stability of these three drugs in these buffer solutions. By knowing the room-temperature solubility of the drugs in the buffer solution, the stability of the drugs in suspension was predicted. As a result, a 0.02 M phosphate buffer (pH 7.0) containing 0.02% (w/v)polysorbate 20, 1% (w/v) NaCl, and 0.1% (w/v) EDTA was determined to be an acceptable medium. In addition, 0.35% (w/v) high-viscosity carboxymethylcellulose (HV-CMC) was first selected as the suspending agent to enhance the redispersibility of the suspension. Stability data further supported that all three drugs were stable in the suspension containing HV-CMC with less than 5% potency loss for at least 6 months at 40 degrees C and 12 months at 25 degrees C. However, the viscosity drop of this HV-CMC formulation at 25 degrees C and 40 degrees C became a product stability concern. To improve the viscosity stability of the suspension, the medium-viscosity carboxymethylcellulose (MV-CMC) was selected to replace the HV-CMC as the suspending agent. The optimal combination of MV-CMC and sodium chloride in achieving the most desirable dispersion properties for the formulation was determined through the use of a 32 factorial design. The optimal formulation containing 1% MV-CMC and 1% sodium chloride has shown improved viscosity stability during storage and has been used for clinical studies.

4-Hydroxy-2-nonenal increases gamma-glutamylcysteine synthetase gene expression in alveolar epithelial cells

Previous studies from this laboratory demonstrated that 4-hydroxy-2-nonenal (4HNE), a lipid peroxidation product, induces expression of gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in de novo glutathione (GSH) synthesis, in rat alveolar epithelial L2 cells. The present study demonstrates that 4HNE also induces GCS in primary cultured alveolar epithelial type II (AT2) cells. Enzyme activity, protein content, and messenger RNA levels of both the catalytic (GCS-HS) and regulatory (GCS-LS) subunits were significantly increased in AT2 cells treated with 5 or 10 microM 4HNE, the same concentrations that induced GCS expression in L2 cells. As in L2 cells, 4HNE induced a greater AT2-cell increase in GCS-LS than in GCS-HS, suggesting that modulation of GCS-LS may play a dominant role in regulating GSH concentration in response to oxidative stress. Additional studies using mitogen-activated protein kinase pathway inhibitors showed that induction by 4HNE of GCS-HS, but not GCS-LS, was mediated through activation of the extracellular regulated kinase pathway in L2 cells. The results demonstrate that L2 cells maintain the same responsiveness to oxidant challenge as do primary cultured AT2 cells in terms of increasing GSH synthetic capacity, and that different pathways are involved in the induction of two GCS subunits by 4HNE.

Glutathione depletion in PC12 results in selective inhibition of mitochondrial complex I activity. Implications for Parkinson's disease

Oxidative stress appears to play an important role in degeneration of dopaminergic neurons of the substantia nigra (SN) associated with Parkinson's disease (PD). The SN of early PD patients have dramatically decreased levels of the thiol tripeptide glutathione (GSH). GSH plays multiple roles in the nervous system both as an antioxidant and a redox modulator. We have generated dopaminergic PC12 cell lines in which levels of GSH can be inducibly down-regulated via doxycycline induction of antisense messages against both the heavy and light subunits of gamma-glutamyl-cysteine synthetase, the rate-limiting enzyme in glutathione synthesis. Down-regulation of glutamyl-cysteine synthetase results in reduction in mitochondrial GSH levels, increased oxidative stress, and decreased mitochondrial function. Interestingly, decreases in mitochondrial activities in GSH-depleted PC12 cells appears to be because of a selective inhibition of complex I activity as a result of thiol oxidation. These results suggest that the early observed GSH losses in the SN may be directly responsible for the noted decreases in complex I activity and the subsequent mitochondrial dysfunction, which ultimately leads to dopaminergic cell death associated with PD.

Detection of a human parvovirus intrauterine infection with the polymerase chain reaction

OBJECTIVE

To detect human parvovirus B19 intrauterine infection in pregnancy with the polymerase chain reaction (PCR).

STUDY DESIGN

DNA of chorionic villi and amniotic fluid was extracted and the gene of human parvovirus B19 amplified with PCR.

RESULTS

The study analyzed 61 specimens of chorionic villi and 26 specimens of amniotic fluid and found two positive specimens of chorionic villi and 1 positive specimen of amniotic fluid.

CONCLUSION

The vertical transmission of human parvovirus B19 infection in early pregnancy may be a pathway of intrauterine infection. Chorionic villus sampling in early pregnancy and PCR could be developed as a method of prenatal diagnosis of human parvovirus B19 intrauterine infection.

Molecular mechanism of decreased glutathione content in human immunodeficiency virus type 1 Tat-transgenic mice

Human immunodeficiency virus (HIV) progressively depletes GSH content in humans. Although the accumulated evidence suggests a role of decreased GSH in the pathogenesis of HIV, significant controversy remains concerning the mechanism of GSH depletion, especially in regard to envisioning appropriate therapeutic strategies to help compensate for such decreased antioxidant capacity. Tat, a transactivator encoded by HIV, is sufficient to cause GSH depletion in vitro and is implicated in AIDS-associated Kaposi's sarcoma and B cell lymphoma. In this study, we report a decrease in GSH biosynthesis with Tat, using HIV-1 Tat transgenic (Tat+) mice. A significant decline in the total intracellular GSH content in liver and erythrocytes of Tat+ mice was accompanied by decreased gamma-glutamylcysteine synthetase regulatory subunit mRNA and protein content, which resulted in an increased sensitivity of gamma-glutamylcysteine synthetase to feedback inhibition by GSH. Further study revealed a significant reduction in the activity of GSH synthetase in liver of Tat+ mice, which was linearly associated with their GSH content. Therefore, Tat appears to decrease GSH in vivo, at least partially, through modulation of GSH biosynthetic enzymes.

Investigation of the in vitro release of gentamicin from a polyanhydride matrix

Septacin¿trade mark omitted¿ is a sustained release formulation consisting of gentamicin sulfate dispersed in a biodegradable polyanhydride matrix. The polyanhydride matrix is a copolymer of erucic acid dimer (EAD) and sebacic acid in a 1:1 weight ratio. In vitro drug release was performed in both water and pH 7.4 phosphate buffer. The drug release in water was faster than that in the buffer, which was the opposite of what would be expected based upon a faster polymer hydrolysis rate in the buffer. Theoretical treatment of the data using the Peppas model revealed that release in water was anomalous, while the release in pH 7.4 phosphate buffer was diffusion-controlled. Profound bead morphology differences were observed between beads in these two in vitro release media. Cracking was observed in beads in water and swelling with no apparent cracking was seen in beads in buffer. Concurrent monitoring of drug and sebacic acid release indicated that drug release is not via surface erosion. Osmotic effects were found to play little role in the in vitro drug release. There was no spectroscopic evidence of amide formation between the drug and copolymer. Sulfate release was monitored along with drug release and the results indicate that there is ion-exchange occurring during the pH 7.4 in vitro release. It was subsequently demonstrated that gentamicin can form an insoluble salt with EAD. This salt formation explains the slower drug release in pH 7.4 phosphate buffer.

Epidermolysis bullosa of the head and neck: a case report of laryngotracheal involvement and 10-year review of cases at the Hospital for Sick Children

OBJECTIVE

Epidermolysis bullosa (EB) involvement of the head and neck, particularly of the larynx, can represent a challenge to the otolaryngologist. In this article, we present a case report of an infant with laryngeal EB requiring tracheostomy. All cases of EB occurring over the past 10 years at The Hospital for Sick Children are reviewed, and the frequency and extent of head and neck involvement, including that of the larynx and trachea, is described. A review of current literature describing laryngeal EB is presented.

METHOD

The charts of all patients diagnosed with EB from the period November 1986 to July 1997 were extracted and reviewed in detail. A literature review of reports of laryngeal EB over the past 20 years was completed via a Medline search.

RESULTS

Sixteen cases of EB were identified and reviewed. These cases were categorized into the three major subtypes of EB: dystrophic EB, junctional EB, and EB simplex. Three cases of laryngotracheal involvement were reported, one within each subtype. In our literature review, only 18 cases of laryngotracheal EB have been documented in the past 20 years, and most of these were diagnosed with the junctional EB subtype. The overall prognosis for patients with junctional EB based on review of cases in our institution, as well as in our review of literature, was poor.

CONCLUSIONS

The extent of EB involvement of the head and neck is variable, often depending on subtype. Laryngeal involvement with EB is very rare but of significance, since mortality within this group of patients is high, with death resulting most often from sepsis.

Depletion of glutathione by buthionine sulfoxine is cytotoxic for human neuroblastoma cell lines via apoptosis

Buthionine sulfoximine (BSO) selectively inhibits glutathione (GSH) synthesis and has been used to sensitize tumor cells to alkylating agents, but has minimal single-agent cytotoxicity for most cell types. We determined the cytotoxicity of BSO for 18 (12 MYCN amplified; 6 MYCN nonamplified) human neuroblastoma cell lines using DIMSCAN, a digital image microscopy cytotoxicity assay. D-L(R:S) BSO was highly cytotoxic (>3 logs of cell kill) for most neuroblastoma cell lines, with 17/18 cell lines having IC90 values (range 2. 1->1000 microM) below equivalent steady state plasma levels of L(R:S) BSO reported in adult human trials. Cell lines with genomic amplification of MYCN were more sensitive to BSO than MYCN nonamplified cell lines (P = 0.04). D-L(R:S) BSO (500 microM for 72 h) induced apoptosis as detected by DNA laddering, nuclear morphology, and TUNEL staining of DNA fragments using flow cytometry. Maximal cell killing occurred within 48 h and was antagonized byic value in neuroblastoma.

gamma-glutamylcysteine synthetase: mRNA stabilization and independent subunit transcription by 4-hydroxy-2-nonenal

gamma-Glutamylcysteine synthetase (GCS), the rate-limiting enzyme in de novo glutathione (GSH) synthesis, is composed of one catalytic (heavy) and one regulatory (light) subunit. Although both subunits are increased at the mRNA level by oxidants, it is not clear whether they are regulated through the same mechanism. 4-Hydroxy-2-nonenal (4HNE), a lipid peroxidation product, may act as a mediator for the induction of gene expression by oxidants. In the present study, 4HNE was used to study the mechanism of induction of the two GCS subunits in rat lung epithelial L2 cells. 4HNE increased both the transcription rates and the stability of mRNA for both GCS subunits, resulting in an increased mRNA content for both subunits. Both GCS subunit proteins and enzymatic activities also increased. Emetine, a protein synthesis inhibitor, blocked the increase in GCS light subunit mRNA but not the increase in GCS heavy subunit mRNA. This suggested that although 4HNE increased transcription and stabilization of both GCS subunit mRNAs, the signaling pathways involved in the induction of the two GCS subunits differed.

Detection of Chlamydia trachomatis intrauterine infection using polymerase chain reaction on chorionic villi

OBJECTIVE

To detect Chlamydia trachomatis intrauterine infection in the early pregnancy by using chorionic villi.

METHOD

The C. trachomatis infection in pregnant women was investigated by cervical specimens and Clearview kits. DNA of chorionic villi was extracted and the gene of a major outer membrane protein of C. trachomatis was amplified by polymerase chain reaction (PCR).

RESULTS

120 cervical specimens of the pregnant women were analyzed and 10 cervical specimens were positive for C. trachomatis infection. In this study, the prevalence of C. trachomatis infection was approx. 8.3%. Fifty-nine specimens of chorionic villi and three positive specimens of C. trachomatis infection were analyzed by PCR. The incidence of C. trachomatis intrauterine infection in the early pregnancy was 5.1%.

CONCLUSION

The vertical transmission of C. trachomatis infection in the early pregnancy may be a pathway of intrauterine infection. Chorionic villus sampling in early pregnancy and the PCR method could be developed as a technique for prenatal diagnosis of C. trachomatis intrauterine infection.

Quinones increase gamma-glutamyl transpeptidase expression by multiple mechanisms in rat lung epithelial cells

gamma-Glutamyl transpeptidase (GGT) plays an important role in glutathione (GSH) metabolism. GGT expression is increased in oxidant-challenged cells; however, the signaling mechanisms involved are uncertain. The present study used 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a redox cycling quinone that continuously produced H2O2 in rat lung epithelial L2 cells. It was found that DMNQ increased GGT mRNA content by increasing transcription, as measured by nuclear run-on. This was accompanied by increased GGT specific activity. Cycloheximide, a protein synthesis inhibitor, blocked neither the increased GGT mRNA content nor the increased GGT transcription rate caused by DMNQ, suggesting that increased GGT transcription was a direct rather than secondary response. Previous data from this laboratory (R.-M. Liu, H. Hu, T. W. Robinson, and H. J. Forman. Am. J. Respir. Cell Mol. Biol. 14: 186-191, 1996) showed that tert-butylhydroquinone (TBHQ) increased GGT mRNA content by increasing its stability. TBHQ differs markedly from DMNQ in terms of its conjugation with GSH and H2O2 generation. Together, the data suggest that quinones upregulate GGT through multiple mechanisms, increased transcription and posttranscriptional modulation, which are apparently mediated through generation of reactive oxygen species and GSH conjugated formation, respectively.

Adaptation to oxidative stress: quinone-mediated protection of signaling in rat lung epithelial L2 cells

Cells can respond to a sublethal oxidative stress by up-regulating their intracellular glutathione (GSH) pool. Such increased GSH concentration is likely to be protective against further oxidative challenge, and, in fact, pre-exposure to low levels of oxidants confers increased cellular resistance to subsequent greater oxidative stress. Previously, we have shown that pretreatment of rat lung epithelial L2 cells with sublethal concentrations of tert-butylhydroquinone (TBHQ) increases intracellular GSH concentration in a concentration- and time-dependent manner. This increase resulted from up-regulation of both gamma-glutamyltranspeptidase (GGT) and gamma-glutamylcysteine synthetase (GCS). Therefore, we investigated whether such increased GSH concentration protected these cells against a subtle loss in function caused by a subsequent challenge with sublethal concentrations of tert-butyl hydroperoxide (tBOOH) (< or = 200 microM), mimicking a physiological oxidative stress. Activation of L2 cell purinoreceptors with 100 microM ADP caused an elevation of intracellular Ca2+. This response was suppressed by a brief pre-exposure to tBOOH. The inhibition, however, was alleviated dramatically by a 16-hr pretreatment with 50 microM TBHQ. The same TBHQ pretreatment also protected the cells from ATP-depletion induced by tBOOH. L-Buthionine S,R-sulfoximine (BSO), an irreversible inhibitor of GCS, prevented the increase in intracellular GSH and also completely removed the protection by TBHQ in maintaining the ATP level. Thus, pre-exposure to a sublethal level of TBHQ results in protection of cell functions from hydroperoxide toxicity. This protection appears to depend on alteration of the intracellular GSH pool, the modulation of which constitutes an adaptive response to oxidative stress.

Differential enhancement of gamma-glutamyl transpeptidase and gamma-glutamylcysteine synthetase by tert-butylhydroquinone in rat lung epithelial L2 cells

Sublethal quinone-mediated oxidative stress stimulates increases in the activities and mRNA levels of gamma-glutamyl transpeptidase (GGT) and gamma-glutamylcysteine synthetase (GCS) in rat lung epithelial L2 cells [Kugelman, A. et al. 1994. Am. J. Respir. Cell Mol. Biol. 11:586-592; Shi, M. M. et al. 1994. J. Biol. Chem. 269:26512-26517]. The present study demonstrated that the quinone-induced increases in these two enzymes were differentially regulated. L2 cells were exposed to various concentrations of tertiary-butylhydroquinone (TBHQ) for different periods of times. TBHQ increased the activities and the mRNAs for GGT and the catalytic subunit of GCS; however, the time- and concentration-dependencies differed. With 50 microM TBHQ, GCS activity increased significantly by 6 h whereas the activity of GGT was not increased until later. Under the same conditions, the highest GCS-mRNA level observed was at 6 h whereas the mRNA level of GGT increased after 6 h, reached a higher level at 12 h, and then returned to the control level by 24 h. Differences were also observed in the concentration-dependence of mRNA increases between the GGT and GCS. Actinomycin D (an inhibitor of RNA synthesis) abolished the increase of GCS-mRNA but not the increase in GGT-mRNA, suggesting a difference in regulation by TBHQ between these two genes. Nuclear run-on experiments confirmed that the increase of GCS-mRNA, but not GGT-mRNA was due to increased transcription. The increase in GGT-mRNA probably results from a decreased degradation rate. The differences between these two enzymes demonstrate how cells can use multiple mechanisms for regulating gene expression in response to oxidative stress.

Increased gamma-glutamylcysteine synthetase and gamma-glutamyl transpeptidase activities enhance resistance of rat lung epithelial L2 cells to quinone toxicity

Tert-butylhydroquinone (TBHQ) is a monofunctional Phase II enzyme inducer, which produces reactive oxygen species. Incubation with a sublethal concentration of TBHQ increased the activities of both gamma-glutamyl transpeptidase (GGT) and gamma-glutamylcysteine synthetase (GCS), although the mechanisms are different (Liu and colleagues, accompanying manuscript). In this study, we found that TBHQ increased intracellular glutathione (GSH) content in rat lung epithelial L2 cells. L2 cells pretreated with a nontoxic concentration of TBHQ (50 microM) acquired resistance to a subsequent challenge with a normally lethal concentration of TBHQ (200 microM). Pretreatment with L-buthionine S,R-sulfoximine (BSO), an inhibitor of GCS, prevented the TBHQ-induced increase in GSH and markedly diminished resistance to 200 microM TBHQ. Similarly, pretreatment with acivicin, an inhibitor of GGT, also prevented the TBHQ-induced increase in GSH and markedly diminished resistance to 200 microM TBHQ. Nevertheless, blockage of GGT by acivicin could be bypassed using 2-oxothiazolidine-4-carboxylate (procysteine) to provide the cell with a source of cysteine. This allowed an increase in GSH and restored resistance in the TBHQ-pretreated cells. The results suggest that elevation of GCS and GGT activities participated in acquired resistance to quinone toxicity.

Response of [Ah] battery genes to compounds that protect against menadione toxicity

We have studied the response of genes in the dioxin-inducible [Ah] battery to three compounds that protect mouse hepatoma cells (Hepa-1c7c7 wild-type, wt) against menadione toxicity. Pretreatment of wt cells with 25 microM 5,10-dihydroindenol[1,2-b]indole (DHII), 25 microM tert-butylhydroquinone (tBHO) or 10 microM menadione itself, generated substantial protection against toxicity produced by subsequent menadione exposure. The gene response was examined in wt cells, and three mutant lines: CYP1A1 metabolism-deficient (c37 or P1-); nuclear translocation-impaired (c4 or nt-); and AHR-deficient (c2 or r-, containing < 10% of normal functional receptor levels). DHII treatment of wt cells for 12 hr markedly elevated the enzyme activities and mRNA levels of genes in the [Ah] battery: aryl hydrocarbon hydroxylase (Cyp1a1), NAD(P)H:menadione oxidoreductase (Nmol), cytosolic aldehyde dehydrogenase class 3 (Ahd4), and UDP-glucuronosyltransferase form 1*06 (Ugt1*06). Treatment of the c4 and c2 cells with DHII failed to induce mRNA levels of the genes, indicating that induction of the [Ah] gene battery by DHII is aromatic hydrocarbon receptor (AHR)-mediated. On the other hand, neither tBHO nor menadione caused increases in CYPlAl mRNA, but tBHQ significantly enhanced the NMO1, AHD4, and UGT1*06 mRNA levels in all three mutant cell lines. In conclusion, we expect one or more putative electrophile response elements (EpRE), previously found in the regulatory regions of the murine Nmol, Ahd4, and ugt1*06 genes, to be functional in responding to phenolic antioxidants.

Enzyme induction by L-buthionine (S,R)-sulfoximine in cultured mouse hepatoma cells

Induction of Phase II enzymes of the [Ah] gene battery by L-buthionine (S,R)-sulfoximine (BSO) and other agents was examined in mouse hepatoma Hepa-1c1c7 cells. BSO, a nonelectrophilic inhibitor of gamma-glutamylcysteine synthetase (GCS), is routinely used to examine the toxicological implications of GSH depletion. Exposure to BSO for 24 h produced a 75-85% depletion of GSH levels, proportional to the inhibition of GCS activity, as well as small increases in the UDP-glucuronosyltransferase (UGT, 60%) and glutathione transferase (GST, 30%) enzyme activities in Hepa-1 wild-type (wt) cells. However, for the NAD(P)H:menadione oxidoreductase (NMO1) and cytosolic aldehyde dehydrogenase class 3 (AHD4) enzyme activities, BSO produced larger increases (110% and 170%, respectively). The mechanisms of NMO1 and AHD4 induction were examined further. In Hepa-1 wt cells, NMO1 and AHD4 activities were increased by the aromatic hydrocarbon inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and by the electrophile tert-butylhydroquinone (tBHQ), known inducing agents for these enzymes. However, NMO1 and AHD4 were induced in Ah receptor nuclear translocation-defective mutant (c4) cells by BSO and tBHQ, but not by TCDD, suggesting that the induction by BSO and tBHQ is not Ah receptor-mediated. In wt cells, N-acetylcysteine produced a concentration-dependent increase in intracellular cysteine levels, but not GSH levels, in the absence or presence of BSO. Furthermore, N-acetylcysteine had no effect on NMO1 activity under any conditions examined, suggesting that GSH levels per se, rather than change in overall thiol status, might be mediating increased NMO1 activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of [Ah] gene battery enzymes and glutathione levels by 5,10-dihydroindeno[1,2-b]indole in mouse hepatoma cell lines

The murine aromatic hydrocarbon ([Ah]) gene battery consists of at least six genes that code for two functionalizing (Phase I) enzymes and four non-functionalizing (Phase II) enzymes. These enzymes are induced by compounds such as aromatic hydrocarbons and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) that bind to the cytosolic Ah receptor protein. Studies in rodents indicate that certain enzymes of this battery, namely cytochrome P4501A1 (CYP1A1), UDP-glucuronosyltransferase (UGT1*06) and NAD(P)H: quinone acceptor oxidoreductase (NMO1) are induced by the synthetic antioxidant 5,10-dihydroindeno[1,2-b]indole (DHII). The induction of [Ah] gene battery enzymes and the levels of reduced glutathione (GSH) were examined in mouse Hepa-1c1c7 hepatoma wild-type cells (wt), a CYP1A1 metabolism-deficient mutant (c37) and an Ah receptor nuclear translocation-defective mutant (c4). DHII and TCDD increased the activities of ethoxyresorufin O-deethylase, an indicator of CYP1A1 activity, as well as NMO1, UGT1*06, cytosolic aldehyde dehydrogenase class 3 and glutathione S-transferase form A1 in wt cells, but had little or no induction effect in c37 or c4 cells. DHII and TCDD differed in their effects on GSH levels; while DHII increased GSH levels 3-fold in wt, but not at all in c37 or c4 cells, TCDD had no effect on GSH levels in any cell type. However, GSH levels were enhanced in both wt and c4 cells by tert-butyl hydroquinone (TBHQ). L-Buthionine S,R-sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase, prevented DHII-induced increases in wt cell GSH. The increase in GSH levels occurred after 8 h, while the induction of enzymes occurred within 4 h. The induction of the higher GSH levels in wt cells by DHII and TBHQ correlated with increases in intracellular levels of the GSH precursor thiol cysteine, as well as with increased activities of gamma-glutamylcysteine synthetase, the rate-limiting enzyme of GSH synthesis. However, TBHQ-mediated GSH increases in c4 cells were accompanied by increased gamma-glutamylcysteine synthetase activity with no change in intracellular cysteine concentration. The results suggest that DHII induction of [Ah] gene battery enzymes requires a functional Ah receptor, but not the functional gene product CYP1A1. Furthermore, metabolism, possibly via CYP1A1, appears to be required for DHII to enhance intracellular levels of cysteine and GCS activity that result in higher GSH levels.

The role of thiols in mitochondrial susceptibility to iron and tert-butyl hydroperoxide-mediated toxicity in cultured mouse hepatocytes

Cultured hepatocytes derived from the newborn mutant c14CoS/c14CoS mouse (14CoS/14CoS cells) have 3-fold higher levels of reduced glutathione (GSH) and greater resistance to menadione toxicity than hepatocytes derived from the wild-type cch/cch mouse (ch/ch cells). Therefore, we used these cell lines to examine mechanisms of oxidative stress produced by iron and tert-butyl hydroperoxide (TBHP). Both cell types were resistant to 25 microM Fe2+ toxicity in the absence of added TBHP. However, in the presence of Fe2+, striking differences in susceptibility to TBHP toxicity between the cell types were observed. With 25 microM Fe2+, ch/ch cells showed TBHP concentration-dependent toxicity, with total lethality at 500 microM; in contrast, 14CoS/14CoS cells were completely resistant to the lethal effects of this concentration of TBHP. Concentration-dependent TBHP-mediated increases in cytosolic Ca2+, pH, and GSSG/GSH ratios, and decreases in GSH levels, were evident in ch/ch cells. 14CoS/14CoS cells exhibited concentration-dependent TBHP-mediated changes in GSH and GSSG/GSH ratios, but cytosolic Ca2+ and pH remained at control levels. Mitochondrial GSH pools were also diminished by TBHP, although there was no selective depletion; mitochondrial GSH remained at about 14% of total cellular GSH. Both cell types exhibited the same time-dependent decrease in plasma membrane protein thiols and a time-dependent increase in plasma membrane protein carbonyls. However, only ch/ch cells displayed a time-dependent depletion of mitochondrial protein thiols, concomitant with an increase in mitochondrial protein carbonyls, while 14CoS/14CoS cells were resistant to such changes. All of the effects produced by TBHP were prevented by desferoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of protection from menadione toxicity by 5,10-dihydroindeno[1,2,-b]indole in a sensitive and resistant mouse hepatocyte line

Established cell lines derived from newborn livers of c14CoS/c14CoS and cch/cch mice have been shown to be genetically resistant (14CoS/14CoS cells) or susceptible (ch/ch cells) to menadione toxicity. These differences are due in part to relatively higher levels of reduced glutathione (GSH) and NAD(P)H:menadione oxidoreductase (NMO1) activity in the 14CoS/14CoS cells. The indolic membrane-stabilizing antioxidant 5,10-dihydroindeno[1,2-b]indole (DHII) was shown previously to protect against various hepatotoxicants in vivo and in primary rat hepatocytes. This report describes how the 14CoS/14CoS and ch/ch cell lines provide a valuable experimental system to distinguish the mechanism of chemoprotection by DHII from menadione toxicity. The addition of 25 microM DHII produced a time-dependent decrease in menadione-mediated cell death in 14CoS/14CoS cells, with little effect on ch/ch cell viability. The maximum protective effect occurred at 24 hr, although the concentration of DHII remained constant for 48 hr. The protective effect of DHII correlated with enhanced glutathione levels (234% increase at 24hr), as well as induction of four enzymes involved in the detoxification and excretion of menadione: NAD(P)H:menadione oxidoreductase (NMO1, quinone reductase), glutathione reductase, glutathione transferase (GST1A1), and UDP glucuronosyltransferase (UGT1*06), with 24-hr maximum induction of 707, 201, 171 and 198%, respectively. Other biotransformation enzymes not directly involved in menadione metabolism (glutathione peroxidase, cytochromes P4501A1 and P4501A2, copper-, zinc-dependent superoxide dismutase, and NADPH cytochrome c oxidoreductase) were not induced by DHII. Menadione-stimulated superoxide production was inhibited 50% by DHII only in 14CoS/14CoS cells, and the inhibition required 24-hr preincubation. Pretreatment with DHII also protected both cell types against the menadione-mediated depletion of GSH, and the increase in percent (oxidized glutathione GSSG), an indicator of oxidative stress. These results suggest that DHII does not protect against menadione toxicity by virtue of its antioxidant or membrane-stabilizing properties. Rather, it acts by inducing a protective enzyme profile that migates redox cycling and facilitates excretion of menadione.

Menadione toxicity in two mouse liver established cell lines having striking genetic differences in quinone reductase activity and glutathione concentrations

Established cell lines derived from newborn livers of c14CoS/c14CoS and cch/cch mice were examined for differences in menadione toxicity. The 14CoS/14CoS cells exhibit 10-fold higher NAD(P)H:menadione oxidoreductase (NMO1) activity and 3-fold greater concentrations of reduced glutathione (GSH) than the ch/ch cells. In 14CoS/14CoS cells there are also 50% to 3-fold increases in glutathione transferase (GSTA1), UDP glucuronosyltransferase, and the copper, zinc-dependent superoxide dismutase activities. Catalase activity, on the other hand, is six times lower in the 14CoS/14CoS than the ch/ch line. The 14CoS/14CoS cells are two to four times more resistant to menadione killing than ch/ch cells. At concentrations of dicumarol that completely block NMO1 and GSTA1 activities, the 14CoS/14CoS cells show more than twice as much resistance to menadione toxicity than the ch/ch cells. Although superoxide formation is three times higher in untreated 14CoS/14CoS than ch/ch cells, menadione-induced superoxide formation is greater in the dying ch/ch than in the 14CoS/14CoS cells. Cellular resistance to menadione toxicity is correlated with intracellular GSH levels, rather than with the percentage of oxidized glutathione; cytotoxicity is not observed as long as GSH concentrations are sufficiently high (about 5-8 nmol/mg protein). For menadione, the results are consistent with a dominant role of GSH depletion in mediating toxicity and support a protective role for NMO1 activity. This report demonstrates the usefulness of these cell lines as a model system to study mechanisms of oxidative chemically induced toxicity, as well as to understand how intracellular levels of GSH are regulated.

Toxicological studies on the organophosphorous insecticide methyl-ISP

Methyl-ISP, a newly developed organophosphorous insecticide, is used in China to treat and protect plants from pest infestation. Our studies demonstrated that methyl-ISP is metabolized rapidly in rat and mouse. Its toxicity was low, no obvious accumulative toxicity, chronic toxicity, teratogenicity, mutagenicity, reproductive toxicity or delayed neurotoxicity could be observed. It is therefore concluded that methyl-ISP is relatively safe to animals and human subjects. methyl-ISP is now employed to replace the other commonly used insecticide hexachlorobenzene (666) in agriculture. A preliminary study was performed to elucidate the mechanism of intoxication at subcellular levels.

Antitumor activity of vinzolidine in the human tumor clonogenic assay and comparison with vinblastine

Vinzolidine (VZL), a semisynthetic vinblastine (VLB) derivative, was tested against a variety of solid tumors in the human tumor clonogenic assay (HTCA). The emphasis was on continuous drug exposure because of the schedule-dependency of the vincas and long half-life of VZL. Of tumor types with more than ten samples tested, the percentage of cases exhibiting inhibition (50% or less of control) of tumor colony forming units (TCFU) was as follows: melanoma (48%), lung cancer (48%), breast cancer (40%), renal cancer (33%), and ovarian cancer (24%). In tumor types tested less frequently, inhibition of TCFU after continuous or one hour drug exposure was observed in 2/7 colon cancers, 1/3 pancreatic cancers and 3/4 gastric cancers. Paired analysis of tumors tested to both VZL and VLB demonstrated no significant difference in overall activity of these two vinca alkaloids. VZL appears to be a promising drug for clinical trials, with in vitro activity in melanoma, lung and breast cancers. More interesting is the suggestion of activity in gastrointestinal tumors, especially colon cancer which is generally resistant to drugs in the HTCA and in vivo.

Effects of cloned human leukocyte interferons in the human tumor stem cell assay

Clonogenic tumor cells from fresh biopsies of human cancers were cultivated in vitro and tested for sensitivity by continuous exposure to pharmacologically achievable concentrations of either of two highly purified human leukocyte interferon subtypes (IFN-alpha A and IFN-alpha D) prepared by recombinant DNA methods. The interferons were compared on a weight basis at concentrations of 0.4 and 4.0 ng/ml (equivalent to 80 and 800 units of interferon activity for IFN-alpha A and 2.0 and 20 units for IFN-alpha D). Inhibition of tumor colony-forming units (50% of control or less) was observed in 38.1% of the 273 tumors tested against IFN-alpha A, and in 16% of the 71 tumors tested against IFN-alpha D. Of the tumor types with at least ten samples tested against IFN-alpha A, the percentage of cases exhibiting inhibition was as follows: melanoma (51.7%), lung cancer (50%), myeloma (33.4%), ovarian cancer (33.9%), sarcoma (33.3%), adenocarcinoma of unknown primary (30.4%), breast cancer (28%), acute leukemia (30.8%), and renal cancer (23%). More marked inhibition (30% of control or less) was observed in 18.7% of all tumors tested against IFN-alpha A. Of 60 melanomas tested, 18 (30%) exhibited marked in vitro inhibition of growth with IFN-alpha A. Although a smaller number of tumors (71) were tested against IFN-alpha D on a weight basis, it appeared, in general, to be slightly less active than IFN-alpha A (p less than 0.01), and only 8% of tumors tested exhibited marked inhibition over the same dosage range of interferon. Comparison of the dose-response curves for the 68 tumors tested simultaneously against both interferons did not reveal marked interpatient differences in the inhibition curves, although IFN-alpha D was slightly less active overall. Tumors exhibiting at least 50% inhibition of tumor colony formation also proved to be sensitive to a significantly larger number of cytotoxic drugs (tested simultaneously) than the tumors not inhibited with interferon (p less than 0.0001 for IFN-alpha A). We conclude that the in vitro clonogenic assay may aid in targeting tumor types most likely to exhibit interferon sensitivity and assist in case selection for entry into clinical trials with cloned interferons.

Activity of camptothecin, harringtonin, cantharidin and curcumae in the human tumor stem cell assay

The antitumor activity of four investigational natural products (camptothecin, harringtonin, cantharidin and curcumae) obtained from China were tested on human tumor biopsies in an in vitro soft agar clonogenic assay system. Significant antitumor activity was seen with camptothecin against human ovarian cancer and some other adenocarcinomas. Antitumor activity was also observed for harringtonin against adenocarcinoma and sarcoma. Both drugs also appeared to show activity in melanoma and mesothelioma. However, cantharidin and curcumae were relatively ineffective on the human tumors tested. For purposes of comparing the intensity of antitumor effects with standard cytotoxic drugs to those of the four new agents, the ID50 values were calculated. The ratio of ID50S of new drugs to the standard agents doxorubicin, cis-platinum and vinblastine (ID50 of the standard drug/ID50 of tested drug) were 10.2, 64.1 and 1.9 for camptothecin and 1.5, 10.3 and 0.9 for harrington respectively. A relationship was observed between the duration of drug exposure (1 hr prior to plating vs continuous contact in the agar) and inhibition of clonogenic tumor cells for camptothecin, harringtonin and doxorubicin.

Evaluation of new anthracycline analogs with the human tumor stem cell assay

Ten anthracyclines, including doxorubicin (DX) and daunorubicin (DNR), and eight analogs with modifications in structure or stereochemistry of the aglycone and/or the aminosugar moiety were simultaneously tested in serial vitro titration studies against human adenocarcinomas in the human tumor stem cell assay. More than a two-log range in cytotoxicity of the various anthracyclines was observed with the tumors tested. Marked individual differences in sensitivity of specific tumors (breast, lung, peritoneal) were observed for the various analogs. By assessing average effects on survival of tumor colony-forming units (TCFU) in the tumors tested, the three compounds lacking the methoxyl group in position 4 of the aglycone (4-demethoxyDX, 4-demethoxy-4'-epiDX, 4-demethoxyDNR) all proved to be more cytotoxic than their parent compounds. Compounds modified in position 4' of the aminosugar were on average either as toxic (4' epiDX) or more toxic (4'-deoxyDX and 4'-0-methylDX) to TCFU than the parent compound DX. On average, 11-deoxyDX was less toxic than DX or the other eight anthracyclines tested. The results obtained are also in good general agreement with those previously reported for anthracyclines with human tumors in xenografts or cancer patients. These antitumor results viewed in concert with toxicology studies in normal mice (including evidence of a lack of cardiac toxicity) suggest that 4'deoxyDX may prove to be a clinically useful anthracycline analog. We also conclude that use of this clinically predictive in vitro soft agar assay provides a rapid and relatively inexpensive means of simultaneously testing a large number of analogs of a parent compound against a spectrum of human tumors.