[IL-1β inhibitor sensitizes to olaparib in homologous recombination deficiency proficient ovarian cancer cells]

Objective: To investigate the inhibitory effect of combined strategy of poly adenosine diphosphate ribose polymerase (PARP) inhibitor and interleukin-1β (IL-1β) inhibitor on homologous recombination deficiency (HRD)-proficient ovarian cancer cells. Methods: (1) HRD-proficient ovarian cancer cell lines OVCAR3 and CAOV3 were treated with PARP inhibitor olaparib. Screening by RNA sequencing analysis, the expression level of IL-1β was validated by enzyme-linked immunosorbent assay (ELISA) and western blot. (2) The dose-response curves of IL-1β inhibitor diacerein were evaluated by cell counting kit-8 (CCK-8) assays in OVCAR3 and CAOV3 cells. CCK-8 assays were further applied to determine the viabilities of OVCAR3 and CAOV3 cells. (3) To evaluate the synergistic effects of olaparib and IL-1β inhibitor in vivo, the transplanted ovarian cancer model was constructed. BALB/c-nude mice (n=16) were injected intraperitoneally with 1×107 OVACR3 cells labelled with luciferase (OVCAR3-Luc). Immunohistochemistry (IHC) assay was performed to determine nuclear antigen associated with cell proliferation (Ki-67) expression. (4) Blood routine tests, kidney and liver function tests were performed to analyze the toxic reaction of different drug treatments. The potential drug-induced injuries of vital organs including heart, liver, spleen, lungs and kidneys of nude mice were determined by hematoxylin-eosin (HE) staining. Results: (1) The RNA sequencing results showed that the mRNA level of IL-1β was the most significantly increased among the 25 differentially expressed genes in OVCAR3 cells treated with olaparib, compared to the negative control group. Olaparib treatment significantly promoted the secretion and expression of IL-1β protein in both OVACR3 and CAOV3 cells by ELISA [(36.2±3.5) and (49.5±3.5) pg/ml, respectively; all P<0.001] and western bolt (2.87±0.37 and 2.05±0.08, respectively; all P<0.01). (2) The half maximal inhibitory concentration (IC50) value of IL-1β inhibitor was determined as follows: 75 μmol/L for OVACR3 cells and 100 μmol/L for CAOV3 cells. The treatments were divided into four groups including control group, olaparib monotherapy group, IL-1β inhibitor monotherapy group and the combination therapy group. The cell viabilities of each group in OVCAR3 and CAOV3 were determined by CCK-8 assay. The data in each group were showed as follows for OVCAR3 and CAOV3 cells: (100.0±0.4)% and (100.0±3.5)% in control group; (63.1±6.2)% and (63.3±3.8)% in olaparib monotherapy group; (61.6±4.7)% and (63.8±3.5)% in IL-1β inhibitor monotherapy group; and (32.9±5.2)% and (30.0±1.3)% in the combination therapy group. The viability assay showed that the combined strategy exhibited a significant inhibition effect on OVACR3 and CAOV3 cells, compared to the monotherapy group and the control group (all P<0.01). (3) All mice with transplanted tumors of HRD-proficient ovarian cancer cells were randomly divided into four groups, and treated with four different treatments as mentioned above, respectively. After 4 weeks (on day 29), the vivo fluorescence imaging were determined. The results showed that the amount of fluorescence of transplanted tumors was mostly decreased in the combination therapy group [(0.5±0.4)×1010 p/s], compared to the control group [(4.2±1.0)×1010 p/s] or the groups treated with any single drug [(3.1±0.9)×1010, (2.2±0.9)×1010 p/s; all P<0.05]. Mice were then sacrificed under anesthesia, and all transplanted tumors detached and weighed for further investigation. The weight of transplanted tumors was significantly decreased in the combination therapy group [(0.09±0.03) g], compared to that in control group [(0.25±0.05) g] or groups treated with any single drug [(0.17±0.03), (0.19±0.04) g; all P<0.05]. The measurement of the expression of Ki-67 showed that it was significantly decreased in the combination therapy group (0.33±0.10), compared to that in the control group (1.00±0.20) or monotherapy groups (0.76±0.07, 0.77±0.12; all P<0.05). (4) There were no significant differences of body weights, blood routine test, renal and liver function tests among mice with different treatments (all P>0.05). Moreover, no significant injuries were observed in the vital organs among the four groups. Conclusions: The combination of olaparib and IL-1β inhibitor synergistically exhibits significant cytotoxicity in HRD-proficient ovarian cancer cells. Moreover, the blood routine and blood biochemistry results confirmed the biosafety of the combination of olaparib and IL-1β inhibitor.

[Prevalence of osteoporosis and related factors in postmenopausal women aged 40 and above in China]

Objective: To understand the prevalence of osteoporosis and related factors in postmenopausal women aged ≥40 years in China and provide scientific evidence for osteoporosis prevention and control. Methods: Data of this study were from the 2018 China Osteoporosis Epidemiological Survey, covering 44 counties (districts) in 11 provinces in China. Related variables were collected by questionnaire survey and physical measurement, and the BMD of lumbar spine and proximal femur was measured by dual-energy X-ray absorption method. The prevalence of osteoporosis and its 95%CI in postmenopausal women aged ≥40 years were estimated with complex sampling weights. Results: A total of 5 728 postmenopausal women aged ≥40 years were included in the analysis and the prevalence of osteoporosis was 32.5% (95%CI: 30.3%-34.7%). The prevalence of osteoporosis in postmenopausal women aged 40-49 years, 50-59 years, 60-69 years, 70-79 years, and ≥80 years were 16.0% (95%CI:4.5%-27.5%), 18.4% (95%CI:15.9%-20.8%), 37.5% (95%CI:34.5%-40.4%), 52.9% (95%CI: 47.5%-58.3%), and 68.0% (95%CI:55.9%-80.1%) respectively. The prevalence of osteoporosis was higher (P<0.001) in those with education level of primary school or below (47.2%, 95%CI: 43.0%-51.3%) and in those with individual annual income less than 10 000 Yuan, (40.3%, 95%CI: 36.9%-43.7%). The prevalence of osteoporosis was 35.1% in rural areas (95%CI: 32.0%-38.1%), which was higher than that in urban areas (P<0.001). The prevalence of osteoporosis in low weight, normal weight, overweight and obese groups were 69.9% (95%CI: 59.0%-80.8%), 42.2% (95%CI: 38.7%-45.7%), 24.2% (95%CI: 21.3%-27.1%) and 14.6% (95%CI: 11.1%-18.0%), respectively. The prevalence of osteoporosis in those with menstrual maintenance years ≤30 years and in those with menopause years ≥11 years were 46.1% (95%CI:40.8%-51.3%) and 48.2% (95%CI:45.0%-51.3%), respectively. Multivariate logistic analysis showed that age ≥60 years, education level of primary school or below, annual household income per capita less than 10 000 Yuan, low body weight, menstrual maintenance years ≤30 years, menopause years ≥11 years were risk factors of osteoporosis in postmenopausal women in China. Conclusions: The prevalence of osteoporosis was high in postmenopausal women aged ≥40 years in China, and there were differences in osteoporosis prevalence among different socioeconomic groups. Effective interventions should be taken for the prevention and control of osteoporosis in key groups in the future.

[Factors affecting long-term survival of advanced high-grade serous ovarian cancer]

Objective: To identify the factors associated with long-term survival and guide the decision for primary surgery in patients with advanced high-grade serous ovarian cancer(HGSOC). Methods: In this case-control study, clinical parameters, including surgical and non-surgical associated factors, were collected and compared between the patients with short-term (<2 years) and long-term (>5 years) survival who all underwent primary debulking surgery (PDS) followed by carboplatin and paclitaxel chemotherapy from January 2004 to December 2016. Univariate analysis was examined by chi-square test and multivariate analysis was performed by logistic regression analysis. Results: There were 95 cases long-term survival (LTS group) and 77 cases short-term survival (STS group) in 698 newly diagnosed HGSOC patients with International Federation of Gynecology and Obstetrics (FIGO) stage Ⅲc and Ⅳ who met include and exclude criteria. (1) Univariate analysis showed that the proportion of complete cytoreduction with no visible residual disease (R0) at PDS and platinum sensitivity in LTS group were significantly higher than those in STS group (P<0.01). The surgical complexity score (SCS), the preoperative serum CA₁₂₅ level and the ascites volume in the LTS group were significantly lower than those of the STS group (all P<0.05). In the LTS group, the preoperative incidence of lesions in retrograde peritoneum of the bladder, serosal and mesangial membrane of the small intestine, upper abdominal peritoneum and liver parenchyma were significantly lower than those in the STS group (all P<0.05). Multivariate logistic regression analysis showed that platinum sensitivity (OR=0.016, 95%CI: 0.004-0.063, P<0.01), ascites volume >500 ml (OR=3.193, 95%CI: 1.285-7.930, P=0.012), and SCS ≥8 (OR=17.433, 95%CI: 2.281-133.25, P=0.003) were independent factors affecting long-term survival (P>0.05). (2) Totally 37 of 95 in long-term survival and 16 of 77 in short-term survival achieved R0 cytoreduction at PDS. Univariate analysis showed that preoperative serum CA₁₂₅ level, preoperative lesion score, preoperative lesion (DS) score, ascites volume, platinum sensitivity,and SCS were significantly correlated with the R0 PDS (all P<0.05). Multivariate analysis showed that ascites volume >500 ml (OR=5.199, 95%CI: 2.015-13.409, P=0.001), DS >2 (OR=15.264, 95%CI: 5.843-39.874, P<0.01) and SCS ≥4 (OR=4.176, 95%CI: 1.618-10.777, P=0.003) were independent factors associated with R0 cytoreduction. In patients with DS ≤2 or SCS <4, but not those with DS >2 or SCS ≥4, R0 cytoreduction was significantly associated with long-term survival. Conclusion: The intrinsic biology of tumor is the factor influencing long-term survival of advanced HGSOC patients, and those who present with wide intraperitoneal metastases and need to remove multiple organs may not benefit from R0 cytoreduction.

Isotopic determination with molecular emission using laser-induced breakdown spectroscopy and laser-induced radical fluorescence

Molecular emission can be used for isotopic analysis in laser-induced breakdown spectroscopy (LIBS) due to its large isotopic shift. However, spectral weakness and interference have become the main flaws in molecular isotopic analysis, causing deterioration of quantitative accuracy and sensitivity. Here, to overcome these problems, laser-induced radical fluorescence (LIRF) was applied to enhance the molecular spectra and eliminate the spectral interference. The root mean square errors of cross validation (RMSECVs) of boron and carbon isotopes (¹¹BO, ¹⁰BO, ¹²CN, and ¹³CN) improved to 2.632, 5.721, 5.990, and 1.543 at.%, as compared with 16.96, 35.79, 57.10, and 13.89 at.%, respectively, obtained in the case without LIRF. The limits of detection (LoDs) of ¹¹BO, ¹⁰BO, ¹²CN, and ¹³CN were 0.9858, 0.8470, 1.606, and 1.193 at.%, respectively. This work demonstrates the feasibility of LIBS-LIRF to achieve isotopic determination with high accuracy and sensitivity.

Determination of boron with molecular emission using laser-induced breakdown spectroscopy combined with laser-induced radical fluorescence

Boron is an essential element for industry, but it is hard to accurately and rapidly determine high boron content with conventional laser-induced breakdown spectroscopy (LIBS), due to the matrix and self-absorption effect. Using molecular emission is an alternative method for boron content analysis, but its weak spectra are major challenges. Here, boron monoxide (BO) radicals were used to establish calibration assisted by LIBS and laser-induced radical fluorescence (LIBS-LIRF). Two types of BO radical excitations, vibrational ground state excitation (LIRFG) and vibrational excited state excitation (LIRFE), were compared. The results showed that LIRFG achieved better sensitivity with a limit of detection of 0.0993 wt.%, while the LIRFE was more accurate with a root mean square error of cross validation of 0.2514 wt.%. In conclusion, this work provided a potential approach for molecular emission analysis with LIBS-LIRF.

Proprotein convertase 1 mediated proneuropeptide proteolytic processing in ischemic neuron injury

BACKGROUND

Pro-protein processing mechanism plays an important role in neuron injury.

OBJECTIVE

To study the protein convertase 1 (PC1) mediated processing mechanism, the ischemic cellular or tissue proPC1/PC1 or proCgA/CgA (pro-chromogranin A) was analyzed.

METHODS

NS20Y differentiated cells were stressed by 0-6 h of oxygen and glucose deprivation (OGD) in glucose-free DMEM and an anaerobic jar environment. Ischemic C57BL/J mouse model was established by performing 60-min of middle cerebral artery occlusion (MCAO) operation and subsequent 4 or 24-h reperfusion. The TUNEL, immunochemistry, and Western blot methods were used to detect protein expression in ischemic cells or tissues.

RESULTS

The OGD or MCAO stress caused substantial cell death in a dose-dependent manner (p < 0.05 or 0.01). With the increasing OGD dose, proPC1 and PC1 proteins gradually increased (p < 0.05 or 0.01) whereas proCgA and CgA proteins decreased (p < 0.05). In vivo the proPC1 and PC1 expressions presented with a peak at 4-h and then decreased at 24-h reperfusion (p < 0.05 or 0.01). The tissue proCgA and CgA proteins decreased with the increasing reperfusion time (p < 0.05).

CONCLUSIONS

The results suggest that the increasing PC1 expression promoted the transformation of proCgA into CgA or smaller peptides, i.e. Pancreastatin or Secretoneurin, and the PC1 mediated processing plays a critical role (Fig. 4, Ref. 15).

Correlation between interleukin-6 expression in articular cartilage bone and osteoarthritis

This study aimed to investigate the expressional profile of interleukin-6 (IL-6) in articular cartilage bone of osteoarthritis (OA) patients and its correlation with OA. A total of 30 articular cartilage bone samples from knee OA patients, which were collected by knee arthroscopy or articular surgery, comprised the study group, and 30 samples of normal articular cartilage tissue comprised the control group. Both mRNA (messenger ribonucleic acid) and protein levels of IL-6 and matrix metalloproteinase-9 (MMP-9) were measured and compared, and a correlation analysis was performed between the two. The integral optical density (IOD) values of MMP-9 and IL-6 proteins in the study group were 9.21 ± 3.22 and 8.94 ± 3.17, respectively; these were significantly higher (P < 0.05) than those in the control group at 3.14 ± 1.48 and 6.64 ± 1.53, respectively. The IOD values of mRNA transcripts for MMP-9 and IL-6 in the study group were 8.31 ± 2.28 and 8.78 ± 3.43, respectively; these were significantly higher than the values in the control group at 3.52 ± 1.37 and 5.21 ± 1.72 (P < 0.05), respectively. Further, the correlation analysis revealed significantly positive relationships for both protein (r = 0.434, P = 0.001) and mRNA (r = 0.413, P = 0.002) levels between MMP-9 and IL-6. In conclusion, articular cartilage tissues in knee OA patients have higher levels of MMP-9 and IL-6 expression, and these may play a synergistic role in OA pathogenesis.

Rapidly growing mycobacteria in Singapore, 2006-2011

Nontuberculous mycobacteria infection is a growing global concern, but data from Asia are limited. This study aimed to describe the distribution and antibiotic susceptibility profiles of rapidly growing mycobacterium (RGM) isolates in Singapore. Clinical RGM isolates with antibiotic susceptibility tests performed between 2006 and 2011 were identified using microbiology laboratory databases and minimum inhibitory concentrations of amikacin, cefoxitin, clarithromycin, ciprofloxacin, doxycycline, imipenem, linezolid, moxifloxacin, sulfamethoxazole or trimethoprim-sulfamethoxazole, tigecycline and tobramycin were recorded. Regression analysis was performed to detect changes in antibiotic susceptibility patterns over time. A total of 427 isolates were included. Of these, 277 (65%) were from respiratory specimens, 42 (10%) were related to skin and soft tissue infections and 36 (8%) were recovered from blood specimens. The two most common species identified were Mycobacterium abscessus (73%) and Mycobacterium fortuitum group (22%), with amikacin and clarithromycin being most active against the former, and quinolones and trimethoprim-sulfamethoxazole against the latter. Decreases in susceptibility of M. abscessus to linezolid by 8.8% per year (p 0.001), M. fortuitum group to imipenem by 9.5% per year (p 0.023) and clarithromycin by 4.7% per year (p 0.033) were observed. M. abscessus in respiratory specimens is the most common RGM identified in Singapore. Antibiotic options for treatment of RGM infections are increasingly limited.

Differential processing of neuropeptide proprotein in human breast adenocarcinoma

BACKGROUND

The processing of proprotein convertase (PC)-mediated neuropeptide plays a very important role in carcinogenesis and tumor proliferation.

AIM

To investigate proneuropeptide processing mechanism in tumorigenesis and tumor proliferation.

MATERIALS AND METHODS

The expression and processing profiles of PC1, carboxypeptidase E (CPE), PC2, GHRH, or neuropeptide Y (NPY) gene and protein level were investigated between 42 human breast tumor tissues and 21 tumor-adjacent normal tissues.

RESULTS

Gene analyses indicated that the proPC1, CPE, or preproNPY gene had higher expression in the breast tumor tissues, whereas the proPC2 or preproGHRH gene showed lower expression in the tissues. Protein analyses showed that the proPC1, PC1, CPE, GHRH, and preproNPY proteins were upregulated in the tumor tissues, whereas the proPC2, PC2, preproGHRH, and NPY proteins were down-regulated in them. The tissue results were highly corroborated with the serum data from the tumor patients and healthy women.

CONCLUSIONS

The higher PC1 and CPE expressions as well as the transformation of more proGHRH into active GHRH peptide suggest stronger PC1/CPE-mediated neuropeptide processing in the tumor, whereas the lower PC2 expression as well as the transformation of less proNPY into active NPY peptide suggests a weak PC2-mediated processing in it. The alterations of the convertase expressions and processing show that there is a differential proprotein processing system in the tumor, which leads to the abnormal distributions of species, ratio, and concentration of (pro)peptide(s) in the microenvironment of cells. The latter may contribute to cancer progression.

Residue depletion of colistin in swine after intramuscular administration

A newly formulated colistin sulphate solution was prepared in a previous study as a potential agent for intramuscular injection and its effectiveness, toxicity and pharmacokinetics were investigated. In order to provide more information to establish scientific guidance for safe use of this preparation, its residue depletion in swine tissues following intramuscular administration was investigated in this experiment. Fifty healthy cross-bred piglets (13.3 +/- 0.9 kg) were used in this study. Five animals were kept as untreated controls and the other 45 animals were intramuscularly injected with the colistin preparation at a dose of 2.5 mg/kg of body weight. From the treated piglets, 5 animals were randomly selected and sacrificed at different withdrawal times. Liver, kidney and muscle tissues were sampled to examine the colistin residue levels by microbiological assay. The results showed that the colistin residue in liver and muscle decreased quickly and could not be detected at 1 day after the final dosing. However, the residue depletion in the kidneys was much slower than that in other tissues and even a small quantity of drug could be detected at 14 days after withdrawal. Using the method recommended by the Committee for Veterinary Medical Products (CVMP), a withdrawal time of 10 days was established for the safe use of the newly formulated colistin sulphate solution.

An association between sex chromosomal aneuploidy in sperm and an abortus with 45,X of paternal origin: possible transmission of chromosomal abnormalities through ICSI

BACKGROUND

Although it has been speculated that the increased de-novo chromosomal abnormalities in ICSI pregnancies may be associated with an increase of aneuploidy in sperm from infertile men, little direct evidence exists to support this claim. We studied sperm from an infertile man with an abortus from ICSI to determine if increased sex chromosomal aneuploidy in the sperm could have contributed to the karyotype of the abortus.

METHODS

The couple underwent ICSI due to severe oligozoospermia. Spontaneous aborted material was subjected to cytogenetic and molecular tests to ascertain the existence, type and origin of a chromosomal abnormality. Sperm from the man were analysed by multi-coloured fluorescent in-situ hybridization (FISH) with probes specific for chromosomes X, Y and 18.

RESULTS

At 8+ weeks after embryo replacement, the patient spontaneously miscarried. Both cytogenetic and comparative genomic hybridization analysis of aborted material showed a 45,X karyotype. Origin of the abnormality was established as a loss of the paternal X chromosome. FISH analysis of sperm revealed 19.6% (1990/10,164) nullisomy for a sex chromosome and 18.6% (1886/10,164) with XY disomy, which is significantly increased when compared to controls with 0.3% (58/20,429) and 0.1% (20/20,429) respectively (P<0.0001).

CONCLUSIONS

This study indicates that the paternal origin of the 45,X abortus was likely the result of a high level of nullisomy in the sperm and provides evidence for the transmission of chromosomal abnormality from sperm to the conceptus through ICSI.

Cytogenetic and molecular study of a premature male infant with 46,XX derived from ICSI: Case report

We investigated the aetiology of the male phenotype in a premature infant derived from ICSI with a 46,XX karyotype. A karyotypically normal couple underwent ICSI because of obstructive azoospermia in the male partner. Sperm were retrieved by testicular sperm extraction (TESE), cryopreserved, and later used for ICSI. The pregnancy after ICSI ended at 20 weeks. A normal-appearing male was delivered but he did not survive. Umbilical cord blood and placenta were sampled and used for molecular and cytogenetic investigation. The 46,XX karyotype from G-banding in this male infant correlated to a balanced female comparative genomic hybridization (CGH) profile in placental tissue. No PCR amplification of SRY on the p arm of the Y chromosome was observed while fluorescence in-situ hybridization (FISH) with the SRY probe also could not detect the gene in cord blood or placental tissues. CGH and FISH, with X and Y centromeric probes, failed to detect mosaicism in the trophoblast, stroma and amnion. Skewed X-chromosome inactivation (81%) was found in the chorionic villi. The molecular and cytogenetic studies indicated a 46,XX male infant without the SRY gene or 46,XX/XY mosaicism. The possible mechanism in this SRY-negative XX male by ICSI is discussed.

Analysis of portal venous waveform after living-related liver transplantation with pulsed Doppler ultrasound

We evaluate the portal venous waveform (PVW) with pulsed Doppler ultrasound (US) after living-related liver transplantation (LRLT) and correlate it with subsequent abnormalities. In the first 2 wk after LRLT, pulsed Doppler US demonstrated three types of PV waveform (PVW) in 33 recipients: non-phasic PVW in 19 patients, pulsatile in 10, and turbulent in 4. In the pulsatile PVW group, arterio-portal (A-P) shunt was confirmed in three grafts by either arteriograhy or computed tomography during hepatic arteriography. A severe stenosis in the grafted vein was confirmed in one case by both US and venography. The pulsatile PVW in the remaining six cases spontaneously disappeared and turned to the non-phasic PVW without treatment. The graft volume/liver standard volume (GV/SV) ratio was significantly smaller in the pulsatile PV waveform group than in the non-phasic PVW group (p<0.01). In the turbulent PVW group, aneurysmal-like dilatation of the portal vein at the umbilical portion was formed in 3 of the 4 patients. The pulsatile waveform in the PV is frequently observed with pulsed Doppler after LRLT, especially in patients that received small grafts. We should keep in mind that they often disappear without any treatment, although some examples of pulsatile waveforms represent vascular complications.

Autocrine and possible intracrine regulation of HL-60 cell proliferation by macrophage colony-stimulating factor

The abnormal expression of macrophage colony stimulating factor (M-CSF) isoforms, i.e. membrane bound M-CSF (m-M-CSF) and intracellular M-CSF (c-M-CSF), and their receptor were reported in some leukemia and tumor cells. Furthermore, the nuclear localization of them may be related to poor prognosis and metastasis, while the mechanism is uncertain. We previously reported that m-M-CSF and its receptor played auto-juxtacrine and adhesion molecule role in human leukemia cell line J6-1. In this paper, we show that HL-60 cells highly express M-CSF and its receptor. The localization of positive reactions was mainly in cytoplasma and nuclear in HL-60 cells. In cytoplasma and nuclear, three isoforms of M-CSF were found with molecular weight (MW) of 20, 16 and 14 kDa, while one type of m-CSF receptor (M-CSFR) was discovered with MW of 120 kDa. Immunoprecipitation assay showed that these ligands could exist separately or binding with their receptor. Monoclonal antibody (McAb) against M-CSF and anti-sense oligodeoxynucleotides (ASON) blocking M-CSF expression inhibited the proliferation of HL-60 cells. McAb and ASON regulated the expression of cyclin D1/E, CDK2/4 and p16. Simultaneous administration of both McAb and ASON inhibited the proliferation of HL-60 cells and modulate the expression of cyclins at greater degrees. Our results suggested an autocrine and possible an intracrine loop of M-CSF/M-CSFR in HL-60 cells.

Traumatic experiences and the mental health of Senegalese refugees

The purpose of our study was to conduct a preliminary investigation into the experiences and mental health of Senegalese refugees. Although research has established that refugees are more prone to psychiatric illnesses than the general population, little has been written about West African refugees. Our focus was on adult refugees (18 years of age and older) from the Casamance region of Senegal. A total of 80 participants (39 women, 41 men) were randomly selected from refugee camps in The Gambia. The Harvard Trauma Questionnaire and the Hopkins Symptom Checklist-25 were used to assess levels of traumatization and mental health status. Typical of refugees of war, participants reported suffering a large number of various traumas. High prevalence rates of anxiety, depression, and posttraumatic stress disorder were also found in this group. A substantial mental health problem exists within the Senegalese refugee population that may signify a potential human crisis.

Characterization of a putative insulin-responsive element and its binding protein(s) in rat angiotensinogen gene promoter: regulation by glucose and insulin

We previously demonstrated that high glucose activates angiotensinogen (ANG) expression and that insulin inhibits this activation. The present studies aim to investigate whether insulin regulates ANG gene expression in kidney proximal tubular cells at the transcription level via interaction of the putative insulin-response element (IRE) with its binding protein(s) in the 5'-flanking region of the ANG gene. Fusion genes containing various lengths of the 5'-flanking region of the rat ANG gene fused to a human GH (hGH) gene as reporter were constructed and transiently introduced into rat immortalized renal proximal tubular cells (IRPTCs). The expression of the fusion genes was monitored by the amount of immunoreactive hGH secreted into the medium as assayed by a specific RIA for hGH. Insulin inhibited the expression of pOGH (rANG N-1498/+18), pOGH (rANG N-1120/+18) and pOGH (rANG N-882/+18) but not pOGH (rANG N-854/+18), pOGH (rANG N-820/+18), pOGH (rANG N-688/+18) and pOGH (rANG N-53/+18) in high-glucose (i.e. 25 mM) medium. Site-directed mutagenesis of nucleotides N-874 to N-867 (5' CCC GCC CT 3') in the 5'-flanking region of the rat ANG gene abolished the response to insulin. Insulin also inhibited the expression of the fusion gene containing the DNA fragment ANG N-882 to N-855 inserted upstream of the ANG gene promoter (N-53/+18), but had no effect on a mutant of N-882 to N-855. Gel mobility shift assays revealed that the labeled putative rat ANG-IRE motif (N-878 to N-864, 5' CCT TCC CGC CCT TCA 3') was bound to the nuclear proteins of IRPTCS: This binding was displaced by unlabeled ANG-IRE and IRE of human glyceraldehyde phosphate dehydrogenase but not by mutants of ANG-IRE and IRE of the rat glucagon gene. Southwestern blotting analysis revealed that the labeled putative ANG-IRE motif bound to a major nuclear protein with an apparent molecular mass of 48 kDA: Finally, high glucose levels enhanced 48-kDa nuclear protein expression and induced an additional 70-kDa nuclear protein expression in IRPTCs, as revealed by Southwestern blotting. Insulin inhibited both 48- and 70-kDa nuclear proteins expression induced by high glucose levels. Its inhibitory effect was reversed by the presence of PD98059 (an inhibitor of mitogen-activated protein kinase, MAPK) but not by wortmannin (an inhibitor of phosphatidylinositol 3- kinase). These studies demonstrate that insulin action on ANG gene expression is at the transcriptional level. The molecular mechanism (s) of insulin action is mediated, at least in part, via interaction of the functional IRE with unidentified 48- and 70- kDa nuclear proteins in the rat ANG gene and is MAPK dependent.

Effect of renin-angiotensin system blockade on the expression of the angiotensinogen gene and induction of hypertrophy in rat kidney proximal tubular cells

Studies have shown that high levels of glucose and angiotensin II (Ang II) stimulate hypertrophy and the expression of matrix protein genes in mouse proximal tubular cells in vitro. The present study tested the hypothesis that blockade of the renin-angiotensin system (RAS) inhibits the stimulatory effect of high levels of glucose on the expression of the renal angiotensinogen (ANG) gene and the formation of Ang II and subsequently attenuates the induction of hypertrophy in kidney proximal tubular cells. Immortalized rat proximal tubular cells (IRPTC) were cultured in monolayer. The levels of expression of rat ANG and ANG mRNA in the IRPTC were quantified by specific radioimmunoassays for rat ANG (RIA-rANG) and by a reverse-transcription polymerase chain reaction (RT-PCR) assay, respectively. Hypertrophy of IRPTC was analyzed by flow cytometry (FACScan) and cellular protein assay. Our studies showed that losartan (an Ang II (AT(1))-receptor blocker), perindopril and captopril (inhibitors of angiotensin-converting enzyme) blocked the stimulatory effect of a high level of glucose (i.e. 25 mM) on the expression of the rat ANG gene and hypertrophy in IRPTC but not by the Ang II (AT(2))-receptor blocker. Our studies indicate that the blockade of RAS is effective in inhibiting the stimulatory effect of hyperglycemia on the expression of the ANG gene and hypertrophy in IRPTC, supporting the notion that the local formation of intrarenal Ang II may play a role in the development of renal hypertrophy during early diabetes.

Comparative genomic hybridization: a new tool for reproductive pathology

OBJECTIVE

To demonstrate the effectiveness of comparative genomic hybridization (CGH) for analysis of reproductive pathology specimens in clinical cytogenetics laboratories.

DESIGN

A total of 856 CGH analyses were performed on various placental and fetal tissues derived from 368 specimens of spontaneous abortions and on placentas from 219 pregnancies with live-born infants. The live-born infants were clinically evaluated as normally developed, with either a normal birth weight or with intrauterine growth restriction; some live-born infants had an abnormal prenatal triple screen with normal cytogenetic results on amniotic fluid cell cultures.

RESULTS

Comparative genomic hybridization analysis was successfully performed on 856 samples from spontaneously aborted specimens and term placentas. Failure of analysis occurred in 1.6% of samples and was due to an insufficient amount of tissue for DNA extraction. Comparative genomic hybridization identified aneuploidy in 53% of spontaneous abortion samples and 3.1% of term placentas.

CONCLUSIONS

Comparative genomic hybridization analysis is a useful clinical tool for detection of aneuploidy in placental and fetal tissues. It provides a genome-wide screen while eliminating tissue culture failures, culture artifacts, and maternal cell contamination. We present practical guidelines for interpreting CGH profiles derived from human reproductive specimens.

High Levels of Glucose Stimulate Angiotensinogen Gene Expression Via the P38 Mitogen-Activated Protein Kinase Pathway in Rat Kidney Proximal Tubular Cells* *This work was supported by grants from the Medical Research Council of Canada (MT-13420 to J.S.D.C. and J.G.F., and MT-12573 to J.G.F.) and from the NIH (HL-48455 to J.R.I., and D.K-50836 to S.S.T.)

The present studies investigated whether the effect of high levels of glucose on angiotensinogen (ANG) secretion and gene expression in kidney proximal tubular cells is mediated at least in part via the activation of p38 mitogen-activated protein kinase (p38 MAPK). Rat immortalized renal proximal tubular cells (IRPTCs) were cultured in monolayer. The levels of immunoreactive rat ANG (IR-rANG) secreted into the medium and the levels of cellular ANG messenger RNA were determined by a specific RIA for rat ANG and a RT-PCR assay, respectively. Phosphorylation of cellular p38 MAPK was determined by Western blot analysis using the Phospho Plus p38 MAPK antibody kit. High levels of glucose (i.e. 25 mM) and phorbol 12-myristate 13-acetate (PMA; 10(-7) M) increased the secretion of IR-rANG and cellular ANG messenger RNA as well as phosphorylation of p38 MAPK in IRPTCs. This stimulatory effect of high levels of glucose and PMA was blocked by SB 203580 (a specific inhibitor of p38 MAPK), but not by SB 202474 (a negative control of SB 203580). High levels of D-sorbitol or 2-deoxy-D-glucose (i.e. > or = 35 mM) also stimulated the phosphorylation of p38 MAPK, but did not stimulate ANG secretion or gene expression. GF 109203X (an inhibitor of protein kinase C) blocked the stimulatory effect of high levels of glucose and PMA on ANG gene expression, whereas it did not block the effect of high levels of glucose, sorbitol, or 2-deoxy-D-glucose on p38 MAPK phosphorylation in IRPTCs. These studies demonstrate that the stimulatory effect of a high level of glucose (25 mM) on ANG gene expression in IRPTCS may be mediated at least in part via activation of p38 MAPK signal transduction pathway and is protein kinase C independent.

Minority and nonminority pediatricians' care of minority and poor children

BACKGROUND

Although it has been established that minority physicians tend to see more minority and more poor or uninsured patients, pediatrics as a specialty has not been studied in this regard.

OBJECTIVE

To determine if minority pediatricians disproportionately provide care to minority children and to poor and uninsured children, relative to nonminority pediatricians, while controlling for possible confounding variables (socioeconomic background, sex, use of non-English languages in practice, and subspecialty training).

METHODS

In 1996, a stratified random sample of 1044 pediatricians, half of whom were underrepresented minorities (URMs) (African, Native, and Mexican Americans, mainland Puerto Ricans, and other Hispanics) and half of whom were Asian or Pacific Islanders, commonwealth Puerto Ricans, and whites (non-URMs), were surveyed about personal, practice, and patient characteristics.

RESULTS

Multivariate analyses reveal that, independent of other variables, being a URM pediatrician is significantly (P = .001) and positively associated with caring for a greater proportion of minority and Medicaid-insured or uninsured patients. Underrepresented minority pediatricians saw 24 percentage points more minority patients and 13 percentage points more Medicaid-insured or uninsured patients than did non-URM pediatricians.

CONCLUSIONS

Compared with what non-URM pediatricians report, URM pediatricians report caring for significantly (P =.001) more minority and poor and uninsured patients. Given the few pediatricians who are URM, non-URM pediatricians should be adequately prepared to provide care for minority patients, as the proportion of minority children is high and will be increasing significantly in the next several years. Most important, efforts to ensure a racially and ethnically diverse health care workforce should be greatly enhanced, as its diversity, and hence representativeness, will improve the health care system for all Americans.

The Sierra Leonean refugee experience: traumatic events and psychiatric sequelae

Although a number of studies address the mental health status of refugees from a variety of regions in the world, there are no studies of the mental health status of West African refugees. It was the purpose of this study to determine the prevalence of various traumatic events to which a sample of Sierra Leonean refugees have been exposed as well as psychiatric sequelae associated with such exposure. A procedure of probability sampling was used to identify and assess a sample of 55 Sierra Leonean refugees residing in a UNHCR-sponsored camp in The Gambia, West Africa. The Harvard Trauma Questionnaire and the Hopkins Symptom Checklist-25 served as survey instruments. The findings clearly indicate the presence of disturbingly high prevalence rates for various traumatic experiences and psychiatric sequelae. It appears that a significant mental health problem exists that begs to be addressed.

Heme oxygenase-1 is upregulated in the kidney of angiotensin II-induced hypertensive rats : possible role in renoprotection

In this study, we investigated the regulation and physiological role of heme oxygenase-1 (HO-1) in the kidney of rats with hypertension. Rats were continuously administered either angiotensin II (Ang II) or norepinephrine with an osmotic minipump for up to 7 days. Ang II infusion decreased the glomerular filtration rate (GFR) as determined through creatinine clearance (3.2+/-0.2 versus 1.2+/-0.2 mL/min with Ang II infusion, P<0.01) and increased proteinuria (9. 7+/-1.3 versus 28.1+/-7.2 mg/d with Ang II infusion, P<0.01). In contrast, norepinephrine did not alter these laboratory values. Ang II infusion significantly increased HO-1 expression in mRNA (442+/-98% of control at day 5, P<0.01) and protein levels (314+/-49% of control at day 5, P<0.01). Immunohistochemistry showed that in the kidney of normotensive rats, HO-1 was expressed mainly in the basal side in the renal tubules. After Ang II infusion, HO-1 staining was more extensively dispersed in the tubular epithelial cells. The intraperitoneal administration of zinc protoporphyrin, an HO inhibitor, to Ang II-infused rats further decreased GFR (0.8+/-0. 1 mL/min) and increased proteinuria (52.5+/-13.0 mg/d). In contrast, the administration of hemin, an HO inducer, ameliorated the Ang II-induced decrease in GFR (2.4+/-0.2 mL/min) and increase in proteinuria (9.3+/-4.5 mg/d). These data suggest that HO-1 upregulation in the kidney of Ang II-induced hypertensive rats may exert a renoprotective effect against Ang II-induced renal injury.

DNA vaccination using the fragment C of botulinum neurotoxin type A provided protective immunity in mice

Botulinum neurotoxin (BoNT) is one of the most toxic substances known to produce severe neuromuscular paralysis. The currently used vaccine is prepared mainly from biohazardous toxins. Thus, we studied an alternative method and demonstrated that DNA immunization provided sufficient protection against botulism in a murine model. A plasmid of pBoNT/A-Hc, which encodes the fragment C gene of type A botulinum neurotoxin, was constructed and fused with an Igkappa leader sequence under the control of a human cytomegalovirus promoter. After 10 cycles of DNA inoculation with this plasmid, mice survived lethal doses of type A botulinum neurotoxin challenges. Immunized mice also elicited cross-protection to the challenges of type E botulinum neurotoxin. This is the first study demonstrating the potential use of DNA vaccination for botulinum neurotoxins.

Insulin inhibits angiotensinogen gene expression via the mitogen-activated protein kinase pathway in rat kidney proximal tubular cells

The present study aimed to investigate the molecular mechanism(s) of insulin action on angiotensinogen (ANG) secretion and gene expression in kidney proximal tubular cells exposed to high levels of glucose. Immortalized rat proximal tubular cells (IRPTC) were cultured in monolayer. The levels of rat ANG and ANG messenger RNA in the IRPTC were quantified by a specific RIA for rat ANG (RIA-rANG) and by an RT-PCR assay. Insulin inhibited the stimulatory effect of a high level of glucose (25 mM) and phorbol 12-myristate 13-acetate, an activator of protein kinase C) on the secretion of ANG and the expression of the ANG messenger RNA in IRPTC. This inhibitory action of insulin on the ANG secretion and gene expression was blocked by PD98059 (an inhibitor of mitogen-activated protein kinase kinase) but not by Wortmannin (an inhibitor of phosphatidylinositol-3-kinase). PD98059 was effective in inhibiting the phosphorylation of MEK 1/2 and p44/42 MAP kinase in IRPTC stimulated by insulin. These studies demonstrate that insulin prevents the stimulatory effect of high levels of glucose on the expression of the renal ANG gene in IRPTC, at least in part, via the MAPK kinase signal transduction pathway, subsequently inhibiting the activation of the local renal renin-angiotensin system.

Glucocorticoid metabolism in proximal tubules modulates angiotensin II-induced electrolyte transport

The hormonal interactions that regulate electrolyte transport in the proximal tubule are complex and incompletely understood. Since endogenous glucocorticoids and angiotensin II each can affect electrolyte transport in this renal segment, we hypothesized that local metabolism of glucocorticoids by the enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) might alter the response to angiotensin II. Studies were conducted in cultured origin defective SV-40 transformed immortalized renal proximal tubule cells (IRPTC) derived from weanling Wistar rat kidney. The 11beta-HSD contained in these cells uses NADP+, has an apparent Km for corticosterone of 1.6 microM, but functions only as a dehydrogenase (corticosterone --> 11-dehydro-corticosterone). When mounted in modified Ussing chambers, IRPTC generate a transmembrane current, and angiotensin II (10 pM to 10 microM) increases this sodium-dependent current. Cells incubated with corticosterone (100 nM) and the 11beta-HSD inhibitor carbenoxolone (CBX) (1 microM) for 24 hr and then acutely stimulated with angiotensin (10 nM) show a greater rise in current than do cells exposed to corticosterone alone and stimulated with angiotensin (corticosterone + CBX: 64.2% +/- 20.5% vs. corticosterone: 18.8% +/- 5.9%; P < 0.02 at 180 min)[mean +/- SE percentage above baseline, n = 8/group]. Cells exposed to corticosterone (100 nM) or CBX (1 microM) alone for 24 hr and then stimulated with angiotensin II (10 nM) had responses similar to controls. Thus glucocorticoids can enhance angiotensin II-induced electrolyte transport in proximal tubule epithelial cells when local 11beta-HSD is inhibited.

Rat proximal tubule cell line transformed with origin-defective SV40 DNA: autocrine ANG II feedback

The renal proximal tubule (PT) is a major site for a complete tissue renin-angiotensin system (RAS) and produces endogenous angiotensin II (ANG II). The present studies demonstrate autocrine RAS feedback in a line of origin-defective SV40 plasmid transformed immortalized rat PT cells (IRPTC) designated as line 93-p-2-1, which are highly differentiated and express all RAS components. Receptor competition assays and Southern blot following RT-PCR demonstrated that these IRPTC express AT1 and AT2 angiotensin receptor subtypes. Autocrine RAS feedback was examined following exposure to ANG II (10(-8) M), and it was noted that angiotensinogen mRNA increases significantly by 1 h and remains elevated through 24 h. The AT1 blocker losartan prevents this increase. Moreover, ANG II upregulates expression of ANG II receptor mRNA (both AT1 and AT2). Thus the present studies demonstrate positive ANG II feedback with angiotensinogen and ANG II receptors in PTC, suggesting that the main site of such intrarenal feedback in vivo is within PT. ANG II secreted by line 93-p-2-1 is increased by isoproterenol, suggesting beta-adrenergic regulation in IRPTC.

Molecular mechanisms of glucose action on angiotensinogen gene expression in rat proximal tubular cells

BACKGROUND

Clinical studies have shown that the angiotensin-converting enzyme (ACE) inhibitors or angiotensin II (Ang II) receptor antagonists decrease proteinuria and slow the progression of nephropathy in diabetes, indicating that Ang II plays an important role in the development of nephropathy. We have previously reported that high levels of glucose stimulate the expression of rat angiotensinogen (ANG) gene in opossum kidney (OK) proximal tubular cells. We hypothesized that the stimulatory effect of D(+)-glucose on the expression of the ANG gene in kidney proximal tubular cells is mediated via de novo synthesis of diacylglycerol (DAG) and the protein kinase C (PKC) signal transduction pathway.

METHODS

Immortalized rat proximal tubular cells (IRPTCs) were cultured in monolayer. The stimulatory effect of glucose on the activation of polyol pathway and PKC signal transduction pathway in IRPTCs was determined. The immunoreactive rat ANG (IR-rANG) in the culture medium and the cellular ANG mRNA were measured with a specific radioimmunoassay and a reverse transcription-polymerase chain reaction assay, respectively.

RESULTS

D(+)-glucose (25 mM) markedly increased the intracellular levels of sorbitol, fructose, DAG, and PKC activity as well as the expression of IR-rANG and ANG mRNA in IRPTCs. These stimulatory effects of D(+)-glucose (25 mM) were blocked by an inhibitor of aldose reductase, Tolrestat. PKC inhibitors also inhibited the stimulatory effect of D(+)-glucose (25 mM) on the expression of the IR-rANG in IRPTCs. The addition of phorbol 12-myristate 13-acetate further enhanced the stimulatory effect of D(+)-glucose (25 mM) on the expression of the IR-rANG in IRPTCs and blocked the inhibitory effect of Tolrestat.

CONCLUSION

These studies suggest that the stimulatory effect of a high level of D(+)-glucose (25 mM) on the expression of the ANG gene in IRPTCs is mediated, at least in part, via the de novo synthesis of DAG, an activator of PKC signal transduction pathway.

Synergistic effect of dexamethasone and isoproterenol on the expression of angiotensinogen in immortalized rat proximal tubular cells

To investigate whether the expression of angiotensinogen (ANG) in rat kidney proximal tubules is stimulated by dexamethasone and isoproterenol, immortalized rat proximal tubular cells (IRPTC) were cultured in a monolayer. Immunoreactive rat ANG (IR-rANG) in the culture medium was measured by a specific radioimmunoassay (RIA) for rANG. This RIA was developed by employing rabbit antiserum against the purified recombinant rat ANG (rANG). The purified rANG from plasma and the iodinated rANG were used as the hormone standard and tracer, respectively. The RIA is specific for rat ANG and it has no cross-reactivity with other pituitary hormone preparations or other rat plasma proteins. The sensitivity of detection of the RIA is approximately 2 ng of rANG. The levels of IR-rANG in the culture media of IRPTC ranged from 2 to 5 ng/ml/24 hr/10(6) cells. The addition of dexamethasone (10(-13) to 10(-5) M) stimulated the expression and secretion of rANG from IRPTC in a dose-dependent manner, whereas the addition of isoproterenol alone had no effect. However, a combination of both dexamethasone and isoproterenol synergistically stimulated the expression and secretion of rANG by IRPTC. The synergistic effect of dexamethasone and isoproterenol was blocked by the presence of RU 486 (a glucocorticoid receptor antagonist) or propranolol (beta-adrenoceptor blocker). These studies suggest that the addition of dexamethasone and isoproterenol acts synergistically to stimulate the expression and secretion of ANG protein in rat proximal tubules in vivo.

Immortalized rat proximal tubule cells produce membrane bound and soluble megalin

Megalin (gp330), a glycoprotein receptor found on renal proximal tubule cells and several other epithelial cells, is deduced to be a type I integral membrane protein, but may also exist as a cell surface form lacking a cytoplasmic domain. Furthermore, soluble megalin products have been detected in urine, and in culture medium of a rat yolk sac carcinoma cell line, combined with receptor associated protein (RAP). Permanent renal cell lines expressing megalin were unavailable until the recent description of two immortalized rat proximal tubule cell lines (IRPTC). The present study demonstrated megalin on IRPTC surface by immunofluorescence, without surface staining for RAP, which was, however, readily detected within cells. Antibodies to ectodomain megalin epitopes immunoprecipitated megalin products both from cell lysates and culture medium, whereas antibodies to cytoplasmic domain epitopes precipitated megalin only from lysates. Western blots showed two major megalin products in medium, a prominent band at approximately 200 kDa, and a fainter band above 400 kDa, slightly below intact megalin in cell lysates. Anti-receptor associated protein antibodies immunoprecipitated megalin from IRPTC lysates, but not from media. We propose that portions of megalin are spontaneously produced by IRPTC, probably either by cleavage in the ectodomain or release of forms lacking a cytoplasmic domain.

[Effect of adrenomedullin on mesenteric microvessels and microlymphatics in rat]

The dilatant effect of adrenomedullin (ADM), a novel peptide of 52 amino acids, on the mesenteric microvessels and microlymphatics was investigated under microscopic observation. 10(-6) mol/L ADM could also ameliorate alteration of the hemorheology induced by 10(-5) mol/L norepinephrine (NE) or 10(-7) mol/L endothelin (ET). However, this ameliorative response was markedly inhibited in the presence of NG-nitro-L-arginine (L-NNA), an inhibitor for production of nitric oxide.

Kinetic characterization of the endogenous glutathione transferase activity of octopus lens S-crystallin

The kinetic mechanism of the endogenous glutathione transferase (GST) activity of octopus S-crystallin was investigated by steady-state kinetics. Biphasic double-reciprocal plots were obtained for both glutathione and the hydrophobic substrate 1-chloro-2,4-dinitrobenzene (CDNB). Substrate inhibition was observed only for CDNB with Ksi value of 29.7 +/- 0.01 mM. The catalytic constant for S-crystallin was three orders of magnitude smaller than that for the digestive gland GST of the same species. The initial-velocity studies indicated that the enzyme reaction might conform to a steady-state random Bi-Bi kinetic mechanism, being similar to the reaction of GST from other sources. The pH-rate profiles also suggest that the same chemical mechanism for the nucleophilic aromatic substitution between GSH and CDNB was employed for S-crystallin. The interaction of Tyr7 with the bound GSH lowered the pKa value of the sulfhydryl group of GSH to 6.82-6.85, which is 2.32-2.35 pH unit smaller than that found in aqueous solution. This lowering of pKa value produces the thiolate anion of GSH, a better nucleophile to attack the ipso carbon of CDNB, resulting in formation of Meisenheimer complex intermediate. Removing the chloride ion from this intermediate complex produces the conjugate product. Using the method devised by Wang and Srivastava (Anal. Biochem. 216, 15-26, 1994), the functional unit of the dimeric S-crystallin was estimated to be a monomer. The possible biological implications of the endogenous detoxification ability of cephalopods S-crystallin are discussed.

Kinetic mechanism of octopus hepatopancreatic glutathione transferase in reverse micelles

Octopus glutathione transferase (GST) was enzymically active in aerosol-OT [sodium bis-(2-ethylhexyl)sulphosuccinate]/iso-octane reverse micelles albeit with lowered catalytic constant (kcat). The enzyme reaction rate was found to be dependent on the [H2O]/[surfactant] ratio (omega(o)) of the system with maximum rate observed at omega(o) 13.88, which corresponded to vesicles with a core volume of 64 nm3. According to the physical examinations, a vesicle of this size is barely large enough to accommodate a monomeric enzyme subunit. Dissociation of the enzyme in reverse micelles was confirmed by cross-linking of the associated subunits with glutaraldehyde and separation of the monomers and dimers with electrophoresis in the presence of SDS. The kinetic properties of the enzyme were investigated by steady-state kinetic analysis. Both GSH and 1-chloro-2,4-dinitrobenzene (CDNB) showed substrate inhibition and the Michaelis constant for CDNB was increased by 36-fold to 11.05 mM in reverse micelles. Results on the initial-velocity and product-inhibition studies indicate that the octopus GST conforms to a steady-state sequential random Bi Bi mechanism. The results from a log kcat versus pH plot suggest that amino acid residues with pKa values of 6.56 0.07 and 8.81 0.17 should be deprotonated to give optimum catalytic function. In contrast, the amino acid residue with a pKa value of 9.69 0.16 in aqueous solution had to be protonated for the reaction to proceed. We propose that the pKa1 (6.56) is that for the enzyme-bound GSH, which has a pKa value lowered by 1.40-1.54 pH units compared with that of free GSH in reverse micelles. The most probable candidate for the observed pKa2 (8.81) is Tyr7 of GST. The pKa of Tyr7 is 0.88 pH unit lower than that in aqueous solution and is about 2 pH units below the normal tyrosine. This tyrosyl residue may act as a base catalyst facilitating the dissociation of enzyme-bound GSH. The possible interaction of GST with plasma membrane in vivo is discussed.

Metal-catalyzed oxidation and cleavage of octopus glutathione transferase by the Cu(II)-ascorbate system

Glutathione transferase (GST) from octopus hepatopancreas was rapidly inactivated by micromolar concentration of Cu(II) in the presence of ascorbate at neutral pH and 0 degree C. Omitting the metal ion or ascorbate, or replacing the Cu(II) with Fe(II) did not result in any inactivation. Glutathione or the conjugation product of glutathione and 1-chloro-2,4-dinitrobenzene offered complete protection of the enzyme from Cu(II)-induced inactivation. 1-Chloro-2,4-dinitrobenzene, however, did not provide any protection. The inactivation was time and Cu(II) concentration dependent. The dependence of inactivation rate on Cu(II) concentration displayed saturation kinetics, which suggests that the inactivation occurs in two steps with Cu(II) binding with the enzyme first (KdCu = 260 microM), then the locally generated free radicals modify the essential amino acid residues in the active center, which results in enzyme inactivation. The Cu(II)-ascorbate system is, thus, an affinity reagent for the octopus GST. The enzyme inactivation was demonstrated to be followed by protein cleavage. Native octopus GST has a subunit M(r) of 24,000. The inactivated enzyme was cleaved at the C-terminal domain (domain II) of the enzyme molecule and resulted in the formation of peptide fragment of M(r) 15,300, which has the identical N-terminal amino acid sequence as the native enzyme. The other half of the peptide with M(r) approximately 7700 was visible in the gels only after silver staining, which also revealed a minor cleavage site, also located at the domain II, to produce peptide fragments of M(r) approximately 11,300 and 8300. The oxygen carrier molecule in the cephalopods' blood is the copper-containing hemocyanin, which during turnover will release Cu(II). Our results indicate that Cu(II) catalyzes a site-specific oxidation of the essential amino acid residues at the C-terminus of GST causing enzyme inactivation. The modified-enzyme is then affinity cleaved at the putative metal binding site. The ability of octopus GST to bind with free Cu(II) may have important biological implications to enable cephalopods to avoid copper-induced cellular toxicity.

Activity of the molluscicidal plant Millettia thonningii (Leguminosae) toward Biomphalaria glabrata eggs

A dichloromethane extract of the seeds of the molluscicidal west African legume Millettia thonningii was tested for ovicidal activity toward Biomphalaria glabrata egg masses. The extract was found to be highly ovicidal at concentrations as low as 5 mg/L. Embryonic development of the snails in egg masses was monitored using photomicrographs from which embryonic diameters were estimated. Such measurements revealed that ovicidal effects were developmentally stage specific and normally induced a curtailment of development during the gastrula to trochophore transition.

NF-kappa B and transcriptional control of renal epithelial-inducible nitric oxide synthase

Expression of the inducible isoform of nitric oxide synthase (iNOS) is subject to strict tissue specific transcriptional control. Recently, the NF-kappa B/Rel family of transcription factors, and particularly c-rel, was shown to mediate bacterial lipopolysaccharide (LPS) induction of iNOS in macrophages. Since LPS is only a weak inducer of iNOS in most nonimmune cells, we investigated the role of NF-kappa B in the regulation of iNOS expression in mouse renal epithelial cells. We report that LPS activates NF-kappa B in renal epithelium, but that this is not sufficient for induction of iNOS activity. The NF-kappa B complexes activated by LPS in renal epithelium differ from those in macrophages in that they lack c-rel, which may explain the absence of iNOS induction in renal epithelium. Conversely, LPS and interferon-gamma (IFN) synergize to induce renal epithelial iNOS. Functional iNOS promoter analysis indicate that this synergistic induction requires NF-kappa B. We conclude that NF-kappa B is necessary but not sufficient for the induction of renal epithelial iNOS expression, and that in contrast to macrophages, c-rel does not appear to play a major role in the regulation of renal epithelial iNOS.

Steady-state kinetics and chemical mechanism of octopus hepatopancreatic glutathione transferase

The kinetic mechanism of glutathione S-transferase (GST) from Octopus vulgaris hepatopancreas was investigated by steady-state analysis. Initial-velocity studies showed an intersecting pattern, which suggests a sequential kinetic mechanism for the enzyme. Product-inhibition patterns by chloride and the conjugate product were all non-competitive with respect to glutathione or 1-chloro-2,4-dinitrobenzene (CDNB), which indicates that the octopus digestive gland GST conforms to a steady-state sequential random Bi Bi kinetic mechanism. Dead-end inhibition patterns indicate that ethacrynic acid ([2,3-dichloro-4-(2-methyl-enebutyryl) phenoxy]acetic acid) binds at the hydrophobic H-site, norophthalmic acid (gamma-glutamylalanylglycine) binds at the glutathione G-site, and glutathione-ethacrynate conjugate occupied both H- and G-sites of the enzyme. The chemical mechanism of the enzyme was examined by pH and kinetic solvent-isotope effects. At pH (and p2H) = 8.011, in which kcat. was independent of pH or p2H, the solvent isotope effects on V and V/KmGSH were near unity, in the range 1.069-1.175. An inverse isotope effect was observed for V/KmCDNB (0.597), presumably resulting from the hydrogen-bonding of enzyme-bound glutathione, which has pKa of 6.83 +/- 0.04, a value lower by 2.34 pH units than the pKa of glutathione in aqueous solution. This lowering of the pKa value for the sulphydryl group of the bound glutathione was presumably due to interaction with the active site Tyr7, which had a pKa value of 8.46 +/- 0.09 that was raised to 9.63 +/- 0.08 in the presence of glutathione thiolate. Subsequent chemical reaction involves attacking of thiolate anion at the electrophilic substrate with the formation of a negatively charged Meisenheimer complex, which is the rate-limiting step of the reaction.

Autocrine inhibition of Na+/K(+)-ATPase by nitric oxide in mouse proximal tubule epithelial cells

An inducible nitric oxide synthase has recently been described in proximal tubule epithelium. To investigate the effects of proximal tubule NO on Na+/K(+)-ATPase, we induced NO production in mouse proximal tubule epithelial cells by treatment with lipopolysaccharide (LPS) and interferon-gamma (IFN gamma) followed by determinations of ouabain-sensitive ATPase activity. Na+/K(+)-ATPase activity decreased after 4 h of LPS/IFN gamma treatment, reaching maximal inhibition after 24 h (34% reduction in activity). The inhibition of Na+/K(+)-ATPase activity by LPS/IFN gamma was prevented by simultaneous incubation with N omega-nitro L-arginine and markedly blunted by removal of L-arginine from the medium. The NO donors sodium nitroprusside and SIN-1 also inhibited Na+/K(+)-ATPase activity to a similar extent than LPS/IFN gamma. However, treatment with 8-pCPT-cGMP only modestly reduced Na+/K(+)-ATPase activity. Interestingly, superoxide dismutase prevented the inhibitory effects of NO on Na+/K(+)-ATPase activity, suggesting a role for peroxynitrite in this inhibition. We conclude that NO generated by mouse proximal tubule epithelial cell iNOS inhibits Na/K ATPase activity in an autocrine fashion and that this inhibition is accompanied by a reduction in Na-dependent solute transport.

Temperature-sensitive SV40 immortalized rat proximal tubule cell line has functional renin-angiotensin system

Immortalized rat proximal tubule cell (IRPTC) lines should be useful for investigation of proximal tubule (PT) regulation and function but previously have been unavailable. We now report the establishment and characterization of an immortalized transformed, temperature-sensitive IRPTC cell line containing renin-angiotensin system (RAS) components. Primary PT cells prepared from male Wistar rats (4-5 wk old) after collagenase digestion, sieving, and Percoll gradient were cultured on collagen-coated T-75 flasks in Dulbecco's modified Eagle's medium containing 5% fetal calf serum. Subconfluent PT cells were transfected with the temperature-sensitive SV40 mutant viruses (tsA SV40) by direct exposure. After 7-8 wk, several clones were obtained, from which one has been characterized and designated as line 3-2. This cell line appears stable up to 45 passages. Clonal cells transformed with this virus exhibit a transformed phenotype at a permissive temperature of 34 degrees C and grow in multiple layers. When the cells are subsequently placed at a nonpermissive temperature of 41 degrees C, they return to morphology similar to that of untransformed cells of the same lineage. At either 34 degrees C or 41 degrees C, this cell line expresses a variety of PT markers including alkaline phosphatase, cytokeratin, carbonic anhydrase, and glucose transporter isoform 2 (GLUT2), while not expressing factor VIII. Uniquely, these cells also appear to express PT proteins gp330 and CHIP28, markers which are usually lost in cultured cells. Furthermore, the cell line expresses protein and mRNA components of RAS, including angiotensinogen, angiotensin converting enzyme, and renin. The IRPTC cell line expresses few angiotensin II (ANG II) receptors at 34 degrees C, the permissive temperature. However, at the nonpermissive temperature, 41 degrees C, IRPTC expresses ANG II receptor (dissociation constant of 0.7 nM; maximum binding capacity of 265 fmol/mg protein). ANG II (10(-8) M) induced a transient rise in cytoplasmic Ca2+ concentration, which was nearly abolished with losartan but not PD-123319, suggesting this finding is AT1 receptor mediated. This cell line should provide an excellent model of PT and should make it possible to study the cell and molecular biology of the RAS, as well as other regulatory systems of the PT.

Guanosine triphosphate cyclohydrolase I regulates nitric oxide synthesis in renal proximal tubules

The synthesis of nitric oxide by proximal tubule-inducible nitric oxide synthase requires tetrahydrobiopterin as a cofactor. To determine whether tetrahydrobiopterin synthesis is required for nitric oxide production, nitrite release by mouse proximal tubule cells treated with 2,4-diamino-6-hydroxypyrimidine, an inhibitor of the rate-limiting enzyme in the de novo synthesis of tetrahydrobiopterin from guanosine triphosphate, guanosine triphosphate cyclohydrolase I, was measured. Treatment with lipopolysaccharide (0.1 micrograms/mL) and interferon-gamma (100 U/mL) for 12 h increased nitrite production from 2.7 +/- 0.2 to 25.4 +/- 1.3 nmol/mg of protein (P < 0.001; N = 9). 2,4-Diamino-6-hydroxypyrimidine (6 mM) reduced lipopolysaccharide/interferon-gamma-induced nitrite production by 53.1 +/- 3.4%. Sepiapterin, a substrate for tetrahydrobiopterin synthesis via the dihydrofolate reductase-dependent pterin salvage pathway, prevented the inhibition by 2,4-diamino-6-hydroxypyrimidine, an effect that was blocked by methotrexate. In conclusion, guanosine triphosphate cyclohydrolase I activity is required for cytokine-induced nitric oxide production by proximal tubular epithelium. The inhibition of guanosine triphosphate cyclohydrolase I could prove useful in the treatment of nitric oxide-mediated renal disorders.

Molecular-Structure of bis(ethane-1,2-diolato)( tetraphenylporphyrinato )phosphorus(V) chloride: [P( tpp )(OCH2CH2OH)2]+Cl -

The structure of bis(ethane-1,2-diolato)( tetraphenylporphyrinato )phosphorus(V) chloride, [P( tpp )(OCH2CH2OH)2]+Cl -, has been confirmed by X-ray diffraction. The cation displays an octahedral coordination about the phosphorus atom and exhibits a ruffled porphyrin geometry with a core size of 1.841 Ǻ. It crystallizes in the orthorhombic space group P212121, with a 12.524(3), b 25.177(5), c 14.275(3) Ǻ, and Z = 4. Refinement based on 4194 observed reflections led to a final R value of 5.1%. The displacement of the phosphorus atom from the porphyrin mean plane is 0.014 Ǻ. The geometry around the phosphorus centre of the [P( tpp )(OCH2CH2OH)2]+Cl- molecule has P-O(1) 1.643(4), P-O(3) 1.642(4) and P- Np 1.841(4) Ǻ. n.m.r. spectroscopy provides a complementary method for the investigation of the ethane-1,2-diolate ligand. The 13C resonances (24°C) of this axial ligand were observed at 62.9 [P-O-C-C-OH, with 2J(P,C) 16.1 Hz] and 57.8 ppm [P-O-C-C-OH with 3J(P,C) 19.1 Hz].

Isolation and characterization of octopus hepatopancreatic glutathione S-transferase. Comparison of digestive gland enzyme with lens S-crystallin

Glutathione S-transferase from Octopus vulgaris hepatopancreas was purified to apparent homogeneity by single glutathione-Sepharose-4B affinity chromatography with overall yield 46% and purification 249-fold. The enzyme was a homodimer with subunit M(r) 24,000, which was smaller than that of the octopus lens S-crystallin (M(r) 27,000) with glutathione-S-transferase-like structure. Both proteins showed substrate specificities similar to alpha/pi-type isozyme of glutathione S-transferase. Under native conditions, both proteins exhibited multiple forms upon polyacrylamide gel electrophoresis or isoelectric focusing, albeit with distinct mobilities; however, only one kind of N-terminal amino acid sequence was determined for the multiple forms of each protein. The hepatopancreatic GST, with pI value 6.6-7.3, dissociated into two monomers in an acidic or alkaline environment. Two amino acid residues, with pKa values 5.69 +/- 0.14 and 9.03 +/- 0.11 were involved in the subunit interactions of the hepatopancreatic enzyme.

Distribution and function of cardiac angiotensin AT1- and AT2-receptor subtypes in hypertrophied rat hearts

To determine distribution and function of cardiac angiotensin (ANG) II receptor AT1 and AT2 subtypes in left ventricular (LV) hypertrophy (LVH), ANG II (10(-8) M) was infused into isolated rat hearts with hypertrophy from aortic banding and into sham-operated controls. ANG II was infused alone or in the presence of AT1 inhibitor [losartan (10(-5) M) or CL-329167 (10(-7) M)] or AT2 inhibitor [CG-42112A (10(-8) M]. ANG II alone caused less increase in coronary vascular resistance (CVR) in LVH compared with control hearts (19 vs. 39%; P < 0.01), although baseline CVR was higher in LVH hearts. This was prevented by AT1 but not AT2 antagonists. ANG II also increased LV end-diastolic pressure in LVH hearts, signifying decreased diastolic relaxation that was prevented by AT1 but not AT2 inhibition. Characterization of ANG II binding sites in LV membrane preparations revealed similar dissociation constants between groups (1.6 +/- 0.95 vs. 2.2 +/- 2.0 nM; not significant) but lower maximum binding capacity in the LVH group (21.1 +/- 5.9 vs. 33.5 +/- 3.0 fmol/mg protein; P < 0.05). Competition assays demonstrated that control left ventricles contain predominantly the AT1 subtype (68.8 +/- 20%), whereas LVH ventricles contain primarily the putative AT2 subtype (59.8% +/- 10.8%; P < 0.05). This suggests that receptor subtype redistribution occurs in LVH with AT1 subtype down-regulation. Nonetheless, the AT1 subtype mediates the effects of ANG II on coronary tone and diastolic dysfunction in pressure-overload hypertrophy.

Renin and angiotensinogen mRNA expression in the kidneys of rats subjected to long-term bile duct ligation

Activation of antinatriuretic systems such as the renin-angiotensin system, is of major importance in the pathogenesis of sodium retention in cirrhosis. In this study, we studied the intrarenal renin-angiotensin system by measuring renin and angiotensinogen mRNA expression in the kidney of rats subjected to long-term bile duct ligation in a phase before the development of ascites, when sodium retention is already present. Experiments were performed in sham-operated and bile duct-ligated rats 3 wk after surgery. Balance studies showed lower sodium excretion and greater sodium retention in the bile duct-ligated rats compared with the control animals. Plasma renin activity (4.41 +/- 1.01 ng Angiotensin I/ml/hr in the bile duct-ligated group vs. 4.20 +/- 0.74 in the controls) and plasma renin concentration were not different between the two groups. However, plasma renin substrate was significantly decreased in bile duct-ligated animals. Total kidney renin mRNA was significantly higher in the bile duct-ligated animals (0.83 +/- 0.14 densitometric units vs. 0.44 +/- 0.04 in the controls), as determined on Northern-blot analysis and densitometric quantitation. Angiotensinogen mRNA expression in the kidneys of bile duct-ligated rats was significantly decreased (0.09 +/- 0.01 densitometric units) compared with that of the controls (0.21 +/- 0.03). These results indicate that sodium-retaining, nonascitic bile duct-ligated rats show abnormalities of the intrarenal renin angiotensin system that precede changes in plasma renin activity. Our data suggest that the intrarenal renin angiotensin system may participate in the initiation of the renal pathophysiological abnormalities present in bile duct-ligated rats.

Purification and kinetic mechanism of the glutathione S-transferase from C6/36, an Aedes albopictus cell line

Glutathione S-transferase from an Aedes albopictus cell line, C6/36, was purified to apparent homogeneity by a single glutathione-Sepharose 4B affinity chromatography, with an overall yield of 66% and 226-fold purification. The enzyme is presumably a homodimer with subunit M(r) 23,000, which is similar to the enzyme isolated from other sources. Under native conditions, the enzyme exhibited multiple forms upon isoelectric focusing or polyacrylamide gel electrophoresis, and all these forms retained enzymatic activity. The pI value of the purified enzyme was distributed between approximately 4.7 and 5.4 with major form at 4.9. The purified enzyme lost 63% activity at -20 degrees C within 1 week. Stability of the purified enzyme was greatly improved by the addition 10 mg/ml of bovine serum albumin, under which only 7% activity was lost after 1 week at -20 degrees C. Activation energy for the enzyme-catalyzed conjugation of glutathione with 1-chloro-2,4-dinitrobenzene was found to be 49.1 kJ/mol. The enzyme could utilize 1-chloro-2,4-dinitrobenzene and ethacrynic acid as substrate, but not bromosulfophthalein, cumene hydroperoxide, or trans-4-phenyl-3-buten-2-one. The initial-velocity and product-inhibition studies indicated that the enzyme reaction conformed to a steady-state random Bi-Bi kinetic mechanism, which was similar to the glutathione S-transferase from other sources. The kinetic data also indicated a synergistic effect between the binding of glutathione G-site and that of organic electrophilic substrate in the H-site of the enzyme active center. The biological significance of the conjugation reaction is discussed.

Angiotensin converting enzyme in renal ontogeny: hypothesis for multiple roles

Angiotensin converting enzyme (ACE) has multiple effects both as the enzyme which cleaves angiotensin II from angiotensin I and as that which breaks down bradykinin. The present study examines ACE mRNA and protein expression in the rat kidney during development. Changes in distribution and expression during development are consistent with suggestions that the renin angiotensin system is important in growth modulation, vascular development and regulation, and protein reabsorption.

Regulation of intrarenal and circulating renin-angiotensin systems in severe heart failure in the rat

OBJECTIVE

Activation of the intrarenal renin-angiotensin system may contribute to the pathophysiology of heart failure by accelerating the generation of angiotensin II at local sites within the kidneys. Activation of the local intrarenal renin-angiotensin system occurs in rats and with mild heart failure. The aim of the present study was to examine components of the circulating as well as the intrarenal renin-angiotensin system in rats with severe heart failure.

METHODS

Six weeks after experimental myocardial infarction (heart failure, HF; n = 8) or sham operation (control, C; n = 6), haemodynamics and the circulating and intrarenal components of the renin-angiotensin system were studied.

RESULTS

HF rats were characterised by large infarctions (scar tissue > 40% of the left ventricular circumference). In comparison to sham operated controls, large myocardial infarctions resulted in severe heart failure with decreased systolic [108(SEM 3) mm Hg v 132(3) in C; p < 0.001] and diastolic arterial blood pressure [83(3) mm Hg v 95(2) in C; p < 0.05], decreased left ventricular systolic pressure [109(3) mm Hg v 132(3) in C; p < 0.005] and increased left ventricular end diastolic pressure [27(2) mm Hg v 5(1) in C; p < 0.0001]. In rats with severe heart failure, the circulating renin-angiotensin system was activated, with an increase in plasma renin activity (3.5-fold, p < 0.05) and plasma angiotensin II concentration (threefold, p < 0.01). In parallel, the intrarenal renin-angiotensin system was activated in severe heart failure. Increases occurred in renal renin mRNA level (1.7-fold, p < 0.01), renal angiotensinogen mRNA level (1.8-fold, p < 0.05), and renal angiotensin II concentration (twofold, p < 0.05) compared to C. Intrarenal angiotensin II concentrations exceeded plasma levels by a factor of 50 and were positively correlated with renal angiotensinogen mRNA levels (r = 0.874, p < 0.001), suggesting that local synthesis is the major source of angiotensin II found in the kidney.

CONCLUSIONS

The intrarenal renin-angiotensin system may be selectively activated in mild heart failure, while both circulating and intrarenal renin-angiotensin systems are induced as the extent of left ventricular function worsens.