Whole-genome sequencing analysis in fetal structural anomalies: novel phenotype-genotype discoveries.

OBJECTIVES: The identification of structural variants and single-nucleotide variants is essential in finding molecular etiologies of monogenic genetic disorders. Whole-genome sequencing (WGS) is becoming more widespread in genetic disease diagnosis. However, data on its clinical utility remain limited in prenatal practice. We aimed to expand our understanding of implementing WGS in the genetic diagnosis of fetal structural anomalies. METHODS: We employed trio WGS with a minimum coverage of 40× on the MGI DNBSEQ-T7 platform in a cohort of 17 fetuses presenting with aberrations detected by ultrasound, but uninformative findings of standard chromosomal microarray analysis (CMA) and exome sequencing (ES). RESULTS: Causative genetic variants were identified in two families, with an increased diagnostic yield of 11.8% (2/17). Both were exon-level copy-number variants of small size (3.03 kb and 5.16 kb) and beyond the detection thresholds of CMA and ES. Moreover, to the best of our knowledge, we have described the first prenatal instance of the association of FGF8 with holoprosencephaly and facial deformities. CONCLUSIONS: Our analysis demonstrates the clinical value of WGS in the diagnosis of the underlying etiology of fetuses with structural abnormalities, where routine genetic tests have failed to diagnose. Additionally, the novel variants and new fetal manifestations have expanded the mutational and phenotypic spectrums of BBS9 and FGF8. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

[Research progress of epigenetic regulation in the pathogenesis of aluminum exposure].

Aluminum is one of the most abundant elements on earth. Aluminum compounds are widely used in food additives, antacids, cooking utensils and so on. Human exposure to aluminum is mainly through diet and drinking water, while excessive intake of aluminum can accumulate in tissues and cause toxic reactions. In the central nervous system, aluminum exposure is closely related to a series of nervous system diseases such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Epigenetic modification refers to the regulation of gene expression without changing the DNA sequence, and its regulatory disorders can lead to abnormalities and diseases of the central nervous system. This paper describes the regulation of epigenetics and its components, including DNA methylation, histone modification and non-coding RNA, in aluminum-induced neurotoxicity, in order to provide insights into the epigenetic mechanism of aluminum-induced neurotoxicity.

[Efficacy and initial clinical evaluation of optical genome mapping in the diagnosis of structural variations].

To investigate the efficacy and value of optical genome mapping (OGM) in detecting chromosomal structural variations. In a clinical study about high-precision analysis of genomic structural variation for complex genetic diseases, a retrospective study was performed on the cases with karyotyping at the department of Obstetrics and Gynecology, and Endocrinology of Peking Union Medical College Hospital from January to December 2021. Ten cases with abnormal karyotype was detected by OGM. Partial cases were verified by fluorescence in situ hybridization (FISH), SNP array or CNV-seq. Results of ten cases, nine were detected with abnormality by OGM, including unbalanced chromosomal rearrangements (n=3), translocation (n=5) and paracentric inversion (n=1), and the results were in concordance with other standard assays. However, one case with breakpoint and reconnected at centromere has not been detected. In conclusion, ten samples were comprehensively analyzed by karyotyping, FISH, SNP array or CNV-seq, and OGM, and results demonstrated that optical genome mapping as a new technology can not only detect unbalanced rearrangements such as copy number variants as well as balanced translocations and inversions, but more importantly, it can refine breakpoints and orientation of duplicated segments or insertions. So it can contribute to the diagnosis of genetic diseases and prevent birth defect. However, the current technology is not yet capable of detecting breakpoints of balanced structural variations lying within unmapped regions.

Prospective evaluation of first-trimester screening strategy for preterm pre-eclampsia and its clinical applicability in China.

OBJECTIVES: To evaluate, in a Chinese population, the performance of a screening strategy for preterm pre-eclampsia (PE) using The Fetal Medicine Foundation (FMF)'s competing-risks model and to explore its clinical applicability in mainland China. METHODS: This was a prospective, multicenter, observational cohort study including 10 899 women with singleton pregnancy who sought prenatal care at one of 13 hospitals, located in seven cities in mainland China, between 1 December 2017 and 30 December 2019. Mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and maternal serum levels of placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks' gestation were measured and converted into multiples of the median using Chinese reference ranges. Individualized risk for preterm PE was calculated using the FMF algorithm. Prior risk was calculated based on maternal demographic characteristics and obstetric history. We evaluated the efficiency of the screening strategy using various combinations of biomarkers and analyzed its predictive performance for a composite of placenta-associated adverse pregnancy outcomes, including PE, placental abruption, small-for-gestational age (SGA) and preterm birth, at fixed false-positive rates for preterm PE. RESULTS: We identified 312 pregnancies that developed PE, of which 117 cases were diagnosed as preterm PE (< 37 weeks' gestation). There were 386 pregnancies complicated by severe composite placenta-associated adverse outcome, including preterm PE, 146 cases of severe SGA (birth weight < 3rd percentile) neonate, 61 cases with placental abruption and 109 cases of early preterm birth < 34 gestational weeks. The triple-marker model containing biomarkers MAP, UtA-PI and PAPP-A achieved, at fixed false-positive rates of 10%, 15% and 20%, detection rates for preterm PE of 65.0%, 72.7% and 76.1%, respectively, and detection rates for severe composite placenta-associated adverse outcome of 34.7%, 41.7% and 46.4%, respectively. Replacing PAPP-A with PlGF or adding PlGF to the model did not improve the performance. Of women screening positive for preterm PE at a fixed 5% false-positive rate, an estimated 30% developed at least one placenta-associated adverse pregnancy outcome, including PE, placental abruption, SGA (birth weight < 10th percentile) and preterm birth < 37 weeks. CONCLUSIONS: The FMF competing-risks model for preterm PE was found to be effective in screening a mainland Chinese population. Women who screened positive for preterm PE had increased risk for other placenta-associated pregnancy complications. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

[Impact of maternal X chromosome aneuploidies on cell free DNA prenatal screening].

Objective: To investigate the impact of maternal X chromosome aneuploidies on cell free DNA (cf-DNA) prenatal screening. Methods: After genetic counseling, invasive prenatal diagnosis was provided for the 124 cases with high risk of sex chromosome aneuploidie (SCA) indicated by cf-DNA prenatal screening. For cases with discordant results of fetal prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte was collected for copy number variation sequencing (CNV-seq) to detect whether the maternal X chromosome was carrying variations. Results: Totally, 124 cases with high risks of SCA indicated by cf-DNA prenatal screening, 9 cases refused to take invasive prenatal diagnosis, while the remaining 115 cases received. Among the 115 cases, 41 cases received accordant results with cf-DNA prenatal screening while 74 cases discordant. Among the 74 cases with discordant results, 19 cases were indicated with maternal X chromosome variations by maternal leukocyte CNV-seq, which accounting for 25.7% (19/74) of the SCA false positive cases, and 15.3% (19/124) of all SCA cases. Conclusions: Pregnant women with X chromosome variations may affect the results of cf-DNA prenatal screening, resulting in false positive or false negative outcomes, it should be emphasized that the cf-DNA results may be affected by maternal X chromosome variations. In cases with discordant results of prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte CNV-seq is recommended to find the reasons of false positive or negative results. And cf-DNA prenatal screening is not recommended for pregnant women who are already known with X chromosome variations.

[Role of BoBs technology in early missed abortion chorionic villi].

Objective: To investigate the value of bacterial artificial chromosome-on-beads (BoBs) technology in the genetic analysis of early missed abortion chorionic villi. Methods: Early missed abortion chorionic villi were detected with both conventional karyotyping method and BoBs technology in Peking Union Medical Hospital from July 2014 to March 2015. Compared the results of BoBs with conventional karyotyping analysis to evaluate the sensitivity, specificity and accuracy of this new method. Results: (1) A total of 161 samples were tested successfully in the technology of BoBs, 131 samples were tested successfully in the method of conventional karyotyping. (2) All of the cases obtained from BoBs results in (2.7±0.6) days and obtained from conventional karyotyping results in (22.5±1.9) days. There was significant statistical difference between the two groups (t=123.315, P<0.01) . (3) Out of 161 cases tested in BoBs, 85 (52.8%, 85/161) cases had the abnormal chromosomes, including 79 cases chromosome number abnormality, 4 cases were chromosome segment deletion, 2 cases mosaic. Out of 131 cases tested successfully in conventional karyotyping, 79 (60.3%, 79/131) cases had the abnormal chromosomes including 62 cases chromosome number abnormality, 17 cases other chromosome number abnormality, and the rate of chromosome abnormality between two methods was no significant differences (P=0.198) . (4) Conventional karyotyping results were served as the gold standard, the accuracy of BoBs for abnormal chromosomes was 82.4% (108/131) , analysed the normal chromosomes (52 cases) and chromosome number abnormality (62 cases) tested in conventional karyotyping, the accuracy of BoBs for chromosome number abnormality was 94.7% (108/114) . Conclusion: BoBs is a rapid reliable and easily operated method to test early missed abortion chorionic villi chromosomal abnormalities.

[Prenatal diagnosis of 17q12 microdeletion syndrome in fetal renal abnormalities].

Objectives: To analyze 3 cases of 17q12 microdeletion syndrome diagnosed prenatally, and to demonstrate clinical phenotype of the syndrome in prenatal setting. Methods: From January 2013 to July 2017, 1 370 women received invasive prenatal diagnosis and chromosome microarray analysis (CMA) in Peking Union Medical College Hospital. Among them, 3 fetuses were diagnosed as 17q12 microdeletion syndrome. All 3 cases were low-risk pregnancies. Abnormal structures in fetal kidney were found in all 3 cases, including 1 case of multiple renal cysts, 2 cases of bilateral hyperechogenic kidneys. These women accepted invasive prenatal diagnosis followed by karyotyping, parental fluorescence in situ hybridization or CMA validation. Results: The second and third trimester ultrasound showed that all 3 fetuses had bilateral renal structural abnormalities, including hyperechogenic kidney, multiple cysts and renal pelvis dilatation. The karyotyping of the 3 fetuses were normal. CMA examination showed that each case had 1.4-1.6 Mb deletion in 17q12 region. Two cases were de novo deletion and 1 case was inherited from the mother who had mild symptoms. The 3 women decided to terminate pregnancies after genetic counseling. Conclusion: 17q12 microdeletion syndrome is a recurrent chromosome microdeletion syndrome, and the unique phenotype in prenatal setting is the abnormal structure of bilateral kidneys. A few cases of 17q12 microdeletion syndrome even inherited normally phenotypical parents, and prenatal genetic counseling of 17q12 microdeletion syndrome is relatively difficult.

[Imaging diagnosis of 95 cases of moderate and severe acute carbon monoxide poisoning].

Objective: To explore the difference of radiological imaging features of delayed encephalopathy after carbon monoxide poisoning (DECMP) and acute carbon monoxide poisoning (ACMP) , and the correlation between the imaging findings and clinical prognosis of the disease. Methods: The correlation between imaging findings and clinical manifestations and prognosis of 95 patients with moderate and severe acute carbon monoxide poisoning were retrospectively analyzed. In the above 95 cases, there were 62 cases of ACMP and 33 cases of DEACMP. All patients underwent conventional CT, MRI and magnetic resonance diffusion tensor imaging (DTI) . Circular regions of interest (ROI) measurement was used for analysis of average diffusion coefficient (ADC) value and fractional anisotropy (FA) value of the MRI and DTI imaging manifestations in different brain regions. Results: The main clinical manifestation of moderate acute carbon monoxide poisoning was consciousness disorder and fatigue; Severe poisoning patients showed deep coma as the main clinical manifestations; The most prominent clinical manifestations of DEACMP were mental disorders and neurological impairment in the extrapyramidal system. A total of 95 cases with moderate or severe CO poisoning showed unilateral or bilateral cerebral cortex, bilateral basal ganglia (white ball) , cerebral white matter around bilateral ventricles or bilateral centrum semiovale, around bilateral ventricles cerebral white matter around bilateral ventricles and bilateral centrum semiovale, cerebral cortex and subcortical involvement. CT showed normal or low density shadow.MRI showed that the lesion T(1)WI presented slightly low or equal signal, T(2)WI and FLAIR sequences showed equal, a slightly higher or high signal; DWI sequence showed slightly higher or high signal. ADC value and FA value in different brain white matter regions of DEACMP group was significantly lower than those of ACMP group (P<0.05) , especially for those around semi oval center and lateral ventricles of the brain white matter (P<0.01) ; The ADC values increased significantly, FA value decreased significantly in the nerve nucleus (P<0.05) , especially for ADC values in globus pallidus (P<0.01) . Conclusion: DTI can evaluate the brain tissue damage in patients with DEACMP more early and more accurately.

Improvement of L-citrulline production in Corynebacterium glutamicum by ornithine acetyltransferase.

In this study, Corynebacterium glutamicum ATCC 13032 was engineered to produce L-citrulline through a metabolic engineering strategy. To prevent the flux away from L-citrulline and to increase the expression levels of genes involved in the citrulline biosynthesis pathway, the argininosuccinate synthase gene (argG) and the repressor gene (argR) were inactivated. The engineered C. glutamicum ATCC 13032 ∆argG ∆argR (CIT 2) produced higher amounts of L-citrulline (5.43 g/L) compared to the wildtype strain (0.15 g/L). To determine new strategies for further enhancement of L-citrulline production, the effect of L-citrulline on ornithine acetyltransferase (EC 2.3.1.35; OATase; ArgJ) was first investigated. Citrulline was determined to inhibit Ornithine acetyltransferase; for 50 % inhibition, citrulline concentration was 30 mM. The argJ gene from C. glutamicum ATCC 13032 was cloned, and the recombinant shuttle plasmid pXMJ19-argJ was constructed and expressed in C. glutamicum ATCC 13032 ∆argG ∆argR (CIT 2). Overexpression of the argJ gene exhibited increased OAT activity and resulted in a positive effect on citrulline production (8.51 g/L). These results indicate that OAT plays a vital role during L-citrulline production in C. glutamicum.

Validation of quantitative fluorescent-PCR for rapid prenatal diagnosis of common aneuploidies in the Chinese population.

Quantitative fluorescent polymerase chain reaction (QF-PCR) is an accurate and reliable method for rapid detection of aneuploidy; however, it is not routinely used in China. We aimed to validate QF-PCR as a means for prenatal common aneuploidy screening and to analyze the heterozygosities of short tandem repeat (STR) markers in the Chinese population. The sequences of 19 STR markers in chromosomes 21, 18, 13, X, and Y were designed; three kinds of fluoresceins were used to label the primers, and the QF-PCR detecting conditions were explored and optimized. The results of analysis of 210 prenatal samples by multiplex QF-PCR were compared with karyotyping analysis. All cases were successfully tested by QF-PCR and conventional cytogenetic analysis. QF-PCR results were consistent with the results of cytogenetic analyses, with the exception of two cases. The sensitivity and specificity of QF-PCR to diagnose common aneuploidies were 94.74 and 100%, respectively. The heterozygosities of most of the markers were lower than reported for Western populations, but relatively similar to those of other Asian populations. We conclude that QF-PCR is able to detect the common aneuploidies for prenatal diagnosis with high detection efficacy; therefore it is suitable for rapid prenatal diagnosis and for large-scale testing in laboratories. However, we need to add new STR markers or to find alternative STR markers with high heterozygosity in order to make this technique useful for routine diagnosis.

The effect of AmtR on growth and amino acids production in Corynebacterium glutamicum.

AmtR, the master regulator of nitrogen control in Corynebacterium glutamicum, plays important roles in nitrogen metabolism. To investigate the influence of AmtR on amino acids production in C. glutamicum ATCC 13032, the amtR deletion strain C. glutamicum Q1 was constructed and cultured in modified CGXII minimal medium for 60 h. The ammonium consumption rates as well as amino acids production of both strains cultured in modified CGXII minimal medium were determined. The amtR deletion in C. glutamicum caused an obvious growth defect in the exponential growth phase, but both strains had the same biomass in the stationary phases. Maybe the less alpha-oxoglutarate was used for the tricarboxylic acid cycle to influence the growth of strains. During 12 h, the rate of ammonium consumption and the concentration of Glu, Pro, Arg and Ser were higher but Asp, Gly, Ile, Leu, Lys were lower in the mutation strain. During 48 h, the Q1 had higher levels of Asp, Lys, Pro, Ala and Val,and lower levels of Glu, Arg, Leu and Ile, compared to the wild. The more Glu was synthesized by the activated GS/GOGAT pathway in Q1, and then the accumulation of relative amino acids (Pro, Arg and Ser) were up-regulated within 12 h growth. After 48 h growth, the amtR deletion obviously influenced accumulation of Ala, Asp and Pro. The amtR deletion could influence the growth and amino acids production, which could be useful to the production of amino acids.

Differences in negative predictive value of prostate MRI based in men with suspected or known cancer.

OBJECTIVE: To compare the negative predictive value (NPV) of multiparametric MRI for Gleason score (GS) ≥ 3+4 cancer and evaluate predictors of these tumors in men with suspected disease and under active surveillance (AS). MATERIALS AND METHODS: This retrospective study included 38 men with suspected prostate cancer and 38 under AS with scans assigned PI-RADS v2 scores 1 or 2 between May 2016 and September 2017. Biopsy results were no cancer, GS = 3+3, or GS ≥ 3+4. Pre-MRI PSA, gland volume, and PSA density were recorded. Chi-square, equality of proportions, and logistic regressions were used to analyze the data. RESULTS: Intermediate to high-grade cancer was found in 12.8% (95% CI = 2.3-23.3) and 35.9% (95% CI = 20.8-50.9) of men with suspected cancer, and under AS (p = 0.02), respectively. The NPV for GS ≥ 3+4 were 87.2% (suspected cancer; 76.7-97.7) and 64.1% (AS; 49.0-79.2). In neither group PSA significantly predicted cancer grade (p = 0.75 and 0.63). Although it did not reach conventional statistical significance, PSA density was a good predictor of cancer grade in men with suspected disease (p = 0.06), but not under AS (p = 0.62). CONCLUSION: The NPV of multiparametric MRI for GS ≥ 3+4 is higher in men with suspected prostate cancer than in men under AS. PSA density ≤ 0.15 improved the prediction of intermediate to high-grade disease in patients without known cancer.

OBJETIVO: Comparar o valor preditivo negativo (VPN) da RM multiparamétrica da próstata para o diagnóstico de tumores escore de Gleason (EG) ≥ 3+4 e avaliar os preditores desses tumores em homens com suspeita de doença e nos sob vigilância ativa (VA). MATERIAIS E MÉTODOS: Este estudo retrospectivo incluiu 38 homens com suspeita de câncer de próstata e 38 em VA com RM, aos quais foram atribuídos escores PI-RADS v2 1 ou 2 entre maio de 2016 e setembro de 2017. Os resultados da biópsia foram ausência de câncer, câncer EG = 3+3 ou câncer EG ≥ 3+4. PSA pré-RM, volume da glândula e densidade de PSA foram anotados. Qui-quadrado, igualdade de proporções e regressões logísticas foram utilizados para analisar os dados. RESULTADOS: Câncer de grau intermediário a alto grau foi encontrado em 12,8% (IC 95% = 2,3­23,3) e 35,9% (IC 95% = 20,8­50,9) dos homens com suspeita de câncer e nos sob VA (p = 0,02), respectivamente. O VPN para GS ≥ 3+4 foi 87,2% (suspeita de câncer; IC 95% = 76,7­97,7) e 64,1% (VA; IC 95% = 49,0­79,2). Em nenhum dos grupos o PSA previu significativamente o grau de câncer (p = 0,75 e 0,63. Embora não tenha alcançado o limiar de significância estatística usual, a densidade de PSA foi um bom preditor de grau de câncer em homens com suspeita de doença (p = 0,06), mas não sob VA (p = 0,62). CONCLUSÃO: O VPN da RM multiparamétrica para GS ≥ 3+4 é maior em homens com suspeita de câncer de próstata do que em homens sob VA. Uma densidade de PSA ≤ 0,15 melhorou a previsão de doença de grau intermediário a alto grau em pacientes sem diagnóstico prévio de câncer.

Systems biology analysis of G protein and MAP kinase signaling in yeast.

Approximately a third of all drugs act by binding directly to cell surface receptors coupled to G proteins. Other drugs act indirectly on these same pathways, for example, by inhibiting neurotransmitter reuptake or by blocking the inactivation of intracellular second messengers. These drugs have revolutionized the treatment of human disease. However, the complexity of G protein signaling mechanisms has significantly hampered our ability to identify additional new drug targets. Moreover, today's molecular pharmacologists are accustomed to working on narrowly focused problems centered on a single protein or enzymatic process. Here we describe emerging efforts in yeast aimed at identifying proteins and processes that modulate the function of receptors, G proteins and MAP kinase effectors. The scope of these efforts is far more systematic, comprehensive and quantitative than anything attempted previously, and includes integrated approaches in genetics, proteomics and computational biology.

An eudesmane glycoside from Fissistigma pallens.

From Fissistigma pallens (Fin. & Gagn.) Merr. (Annonaceae), a Vietnamese folk medicinal plant, a novel eudesmane glycoside named fissispallin (1) has been isolated, besides afzelin. Their structures were elucidated by spectroscopic methods (1H, 13C and 2D NMR).

The aryl hydrocarbon receptor links integrin signaling to the TGF-ß pathway.

Glioblastoma is the most common and aggressive form of intrinsic brain tumor. Transforming growth factor (TGF)-ß represents a central mediator of the malignant phenotype of these tumors by promoting invasiveness and angiogenesis, maintaining tumor cell stemness and inducing profound immunosuppression. Integrins, which are highly expressed in glioma cells, interact with the TGF-ß pathway. Furthermore, a link has been described between activity of the transcription factor aryl hydrocarbon receptor (AhR) and TGF-ß expression. Here we demonstrate that integrin inhibition, using αv, ß3 or ß5 neutralizing antibodies, RNA interference-mediated integrin gene silencing or pharmacological inhibition by the cyclic RGD peptide EMD 121974 (cilengitide) or the non-peptidic molecule GLPG0187, inhibits AhR activity. These effects are independent of cell detachment or cell density. While AhR mRNA expression was not affected by integrin inhibition, AhR total and nuclear protein levels were reduced, suggesting that integrin inhibition-mediated regulation of AhR may occur at a post-transcriptional level. AhR-null astrocytes, AhR-null hepatocytes or glioblastoma cells with a transiently silenced AhR gene showed reduced sensitivity to integrin inhibition-mediated alterations in TGF-ß signaling, indicating that AhR mediates integrin control of the TGF-ß pathway. Accordingly, there was a significant correlation of αv integrin levels with nuclear AhR and pSmad2 levels as determined by immunohistochemistry in human glioblastoma in vivo. In summary, this study identifies a signaling network comprising integrins, AhR and TGF-ß and validates integrin inhibition as a promising strategy not only to inhibit angiogenesis, but also to block AhR- and TGF-ß-controlled features of malignancy in human glioblastoma.

Perlecan (heparan sulfate proteoglycan) gene expression reflected in the characteristic histological architecture of salivary adenoid cystic carcinoma.

In order to determine the role of the basement membrane-type heparan sulfate proteoglycan (HSPG), known as perlecan, in the formation of the characteristic cribriform 'structures of salivary adenoid cystic carcinomas, the mode of expression of mRNA for the core protein of HSPG was investigated by using in situ hybridization (ISH) both in surgical specimens and in a cell system (ACC3) of adenoid cystic carcinomas. In the surgical specimens, the mRNA for the HSPG core was more intensely expressed in solid tumor cell nests, especially in smaller ones. Within the nests, the signals were detected almost exclusively in cuboidal cells forming small pseudocysts. In contrast, signals were absent in flat cells forming large pseudocysts or in carcinoma cell nests attaching to the peripheral nerves or blood vessels. In normal salivary gland tissues, myoepithelial cells expressed the mRNA at a high level, but acinar and duct epithelial cells did not. In the time-course experiment of ACC3 cells, signals for HSPG core increased with time and reached the maximum on day 4, decreasing thereafter in a culture condition in which cells reached confluence in a week. The results indicate that HSPG is biosynthesized by adenoid cystic carcinoma cells which are in the proliferation phase, and that tumor cells producing HSPG tend to form initial structures of stromal pseudocysts.

Structure-activity relationships of anthraquinones as inhibitors of 7-ethoxycoumarin O-deethylase and mutagenicity of 2-amino-3-methylimidazo[4,5-f]quinoline.

The antimutagenicity of 17 natural and synthetic anthraquinones was determined using Salmonella typhimurium TA98 against 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in the presence of Aroclor 1254-induced rat hepatic S9. In general, the relationship between the chemical structures of anthraquinones and their antimutagenicity was found to contain one or more of the following features: (i) C9 carbonyl group, (ii) hydroxyl group at C1 and C4, (iii) C2 ethyl group, and (iv) C3 methyl group. The inhibitory effect of anthraquinones on 7-ethoxycoumarin O-deethylase (ECD) of Aroclor, 1254-induced hepatic microsomes was also examined. In addition, we studied the effect of anthraquinones on the metabolism of IQ by Aroclor 1254-induced microsomes using high-performance liquid chromatography. The antimutagenicity correlated with the inhibition of cytochrome P-450IA2-linked ECD activity in hepatic microsomes, and with the inhibition of N-hydroxy-IQ formation of IQ metabolism by hepatic microsomes. Moreover, we also examined the antimutagenicity of anthraquinones against synthetic N-hydroxy-IQ. Quinizarin and anthraflavic acid were shown to have more effect on the direct mutagenicity of N-hydroxy-IQ than that of the anthraquinones tested. This might explain why both anthraquinones showed higher antimutagenicity; although they inhibited ECD less. These results suggest that there exist at least two mechanisms of action in modifying roles of anthraquinones on the mutagenicity of IQ: (i) mediation through interaction with microsomal activating enzymes to inhibit the major active metabolite of N-hydroxy-IQ formation and (ii) direct interaction with the proximate metabolite of IQ, N-hydroxy-IQ, to block its attack on DNA.

Ventricular arrhythmias late after myocardial infarction are related to hypomagnesemia and magnesium loss: preliminary trial of corrective therapy.

It has been well established that in acute myocardial infarction (MI) many patients display low serum magnesium (Mg). This is associated with complex ventricular arrhythmias. The question arises whether predischarge arrhythmias occurring late after MI might also be related to Mg imbalance. In 118 patients subjected to heart rhythm 24 h Holter monitoring in the second or third week after MI, we investigated (1) the relationship between serum Mg, urinary Mg loss, and ventricular arrhythmias, and (2) the effect of Mg supplementation on heart rhythm disturbances. In patients with undisturbed rhythm or monomorphic ventricular ectopic beats (VEB) (Lown 0-2; n = 84), mean serum Mg level (mg% +/- SD) was 1.83 +/- 0.21, whereas in patients with multifocal VEB, pairs, or nonsustained ventricular tachycardia (VT) (Lown 3-4; n = 34) serum Mg was decreased to 1.68 +/- 0.27 (p < 0.01). Serum Mg normal range in our laboratory is 1.7-2.6 mg%. The lowest serum Mg reaching 1.55 +/- 0.27 was found in nonsustained VT (Lown 4 b) subgroup (n = 14). Urinary Mg loss measured in 81 patients was more pronounced in those with Lown 3-4 arrhythmias (n = 26) than with Lown 0-2 (n = 55). The daily values were 73 +/- 22 and 54.4 +/- 26 mg, respectively (p < 0.001). Thirteen patients with complex arrhythmias and low serum Mg received Mg supplementation (MgSO4, 8 g in 500 ml 5% glucose intravenously during 24 h). This resulted in restoration of almost undisturbed rhythm in 10 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Problems and solutions with the design and execution of an epidemiological study of white spot disease in black tiger shrimp (Penaeus monodon) in Vietnam.

White spot disease (WSD) is caused by white spot syndrome virus (WSSV) and is an acutely fatal pandemic disease of crustaceans. It has resulted in massive losses to the shrimp-farming industry in Asia and has now spread to the Americas. This paper reports the problems and solutions associated with the design and execution of a longitudinal epidemiological study of shrimp (Penaeus monodon) health on farms practising a crop rotation of rice and shrimp in the Mekong Delta of Vietnam. The pre-sampling phase of the project involved selecting an appropriate site and sampling variables, obtaining permission and establishing the necessary laboratory and logistic facilities. At the start of the sampling phase, 40 farmers were selected and 32 of these were visited and interviewed. This resulted in the enrolment of only 17 farmers. A further seven had to be enrolled to obtain the maximum number of farmers that could be sampled by the study team. Compliance was enhanced through meetings, regular visits by senior members of the project team and ensuring that visits were punctual and that all information was treated confidentially. The production cycle began in January 1998 and lasted for approximately 5 months. An attempt was made to collect 500 post larvae (PL) before each pond was stocked to assess the health of the batch and to test for the presence of WSSV by one-step PCR. After stocking, the wild crustaceans also were sampled from the pond for PCR analyses. Information was collected on the management practices and samples of water, pond bottom, feed and shrimp collected throughout the production cycle. Water quality variables with predictable diurnal variation were sampled in the morning and afternoon, twice a week. Two months after stocking, the first outbreak of WSD occurred; subsequently, 18 farms conducted a complete emergency harvest due to the actual or perceived presence of a WSD outbreak. Detectable mortalities were reported from 19 farms, and moribund shrimps were collected from four of these for PCR and histological analyses.