Effect of corn root exudates on the degradation of atrazine and its chlorinated metabolites in soils

DIMBOA (3,4-dihydro-2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3-one), a major benzoxazinone of Poaceae plants, was isolated and purified from corn seedlings. The effect of isolated and purified DIMBOA on the degradation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], and its toxic breakdown products, desethylatrazine [2-chloro-4-amino-6-(isopropylamino)-s-triazine; DEA] and desisopropylatrazine [2-chloro-4-(ethylamino)-6-amino-s-triazine; DIA], was studied in the absence of plants using batch experiments, while the effect of corn root exudates on these compounds was determined in hydroponic experiments. Degradation experiments were performed in the presence and absence of 50 microM, 1 mM, or 5 mM DIMBOA resulting in ratios of DIMBOA to pesticide of 1:1, 20:1, and 100:1. We observed a 100% degradation of atrazine to hydroxyatrazine within 48 h at a ratio of DIMBOA to atrazine of 100:1. DIMBOA had the largest effect on atrazine, while it was about three times less effective on DEA and DIA. Corn (Zea mays L. cv. LG 2185) was exposed to 10 mg L(-1) of either atrazine, DEA, or DIA for 11 d in a growth chamber experiment. Up to 4.3 micromol L(-1) d(-1) of hydroxyatrazine were formed in the nutrient solutions by plants exposed to atrazine, while the formation of hydroxylated metabolites from plants exposed to DEA and DIA was smaller and also delayed. The formation of hydroxylated metabolites increased in the solution with plant age in all atrazine, DEA, and DIA treatments. HMBOA (3,4-dihydro-2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3-one), the lactam precursor of DIMBOA, and a tentatively identified derivative of MBOA (2,3-dihydro-6-methoxy-benzoxazol-2-one) were detected in the corn root exudates. Mass balance calculations revealed that up to 30% of the disappearance of atrazine and DEA, and up to 10% of DIA removal from the solution medium in our study could be explained by the formation of hydroxylated metabolites in the solution itself. Our results show that higher plants such as corn have the potential to promote the hydrolysis of triazine residues in soils by exudation of benzoxazinones.

[Essential osteolysis]

Bei einem 79-jährigen Patienten mit einer progredienten Osteolyse im Bereich der unteren LWS und des Beckens wird nach Ausschuss einer infektiösen, neoplastischen, immunologischen und metabolischen Ursache die Diagnose einer essentiellen Osteolyse oder eines Morbus Gorham-Stout («vanishing bone disease») gestellt. Diese seltene, sporadisch auftretende Erkrankung unbekannter Ätiologie ist gekennzeichnet durch eine lokal fortschreitende Knochendestruktion mit Ersatz durch hämangiomatöses oder lymphangiomatöses Gewebe, das ganze Knochen auflösen und auf angrenzende Knochen übergreifen kann.

New approaches for genotyping of Helicobacter pylori based on amplification of polymorphisms in intergenic DNA regions and at the insertion site of the cag pathogenicity island

The population of the gastric pathogen Helicobacter pylori shows a high degree of genetic diversity. It is well established that heterogeneity at the isolate level is caused by nucleotide transitions within genes, differences in the gene order, and by genetic instability of single genes as well as of a large virulence-associated genomic DNA region, the cag pathogenicity island (PAI). Analysis of intergenic regions with specific PCR-assays developed in this study, revealed that DNA polymorphisms in the noncoding DNA localized in front of the genes ribA and vacA and at the insertion site of the cag PAI contribute to the genetic diversity of H. pylori and are useful for differentiation of individual isolates. Thirteen individual genotypes were identified by PCR analysis of these polymorphic loci in 487, 241, and 182 clinical H. pylori isolates. Sequence analysis revealed that genetic variability in front of genes ribA and vacA, and in the intergenic region at the PAI insertion site is caused by insertion and deletions of so-far-unknown DNA sequences as well as by parts of the H. pylori IS elements IS605 and IS606, respectively. The new genotypes identified could be used to differentiate antrum and corpus isolates from the same patients. Their combination with vacA allele subtypes and with the cagA status allowed to differentiate 140 isolates in 51 subtypes. In 36 cases the corresponding genotype patterns were isolate specific. In summary, the results confirm that DNA polymorphisms in intergenic regions contribute to the genetic diversity of H. pylori. Although individual H. pylori genotypes were not associated with peptic ulcer disease, the PCR-based approaches for their detection developed here should be of use for further investigation of genetic diversity in H. pylori and for epidemiological purposes.

[Upper influx distension in a patient with HIV; unusual localization of an HIV-associated lymphoma]

A 33 year old patient was admitted to the hospital because of deteriorated general condition, upper abdominal pain and progressive dyspnea. He had a positive HIV-serology associated with i.v. drug abuse. The CDC classification on admission was B1. There was no history of opportunistic infections, the patient had refused all prophylactic treatment. The physical examination showed an elevated central venous pressure, decreased breath-sound and percussible dullness, the liver was enlarged and a tumor was palpable on chest. The x-ray of the thorax confirmed a pleural effusion. Cytology of the effusion revealed blasts of malignant non-Hodgkin's lymphoma of B-cell type. A CT-scan of the thorax and abdomen showed a tumor mass in the right ventricle and superior vena cava, a pleural effusion and multiple lesions in the liver. The patient refused a palliative chemotherapy with vincristine and prednisone and died few days after admission.

[Intestinal drug transport: a surgical problem?]

The case of a 35-year-old man is reported, who presented himself in the emergency room with anxiety and hallucinations. He then passed a small oval pack consisting of a dark paste wrapped in cellophane with his stool. This led to the suspicion of a "body packer syndrome" with cocaine intoxication. The plain abdominal X-ray revealed multiple oval structure scattered over the entire gastrointestinal tract. Cocaine metabolites in the urine confirmed the diagnosis. During the following whole-bowel irrigation the patient had a grand mal seizure. In order to accelerate the retrieval of this threatening load, surgical evacuation was immediately executed. 78 packs containing 650 grams cocaine were removed through a gastrotomy and a coecotomy, respectively. Two of these packs were leaking. Following an uneventful postoperative course the patient was discharged from the hospital 11 days later. According to the literature the recommended treatment for cocaine body packers is whole bowel irrigation. Operative treatment is mandatory in cases of small bowel obstruction or drug intoxication due to leaking packs.

Parvovirus B19 infection during pregnancy and development of hydrops fetalis despite the evidence for pre-existing anti-B19 antibody: how reliable are serological results?

BACKGROUND

Primary infection with human parvovirus B19 during pregnancy can lead to fetal hydrops, abortion, or stillbirth. However, reinfection in the presence of pre-existing anti-B19 antibody is generally assumed to have no significant effect on the developing fetus.

OBJECTIVES

To describe a case of fetal loss at 28 weeks' gestation associated with parvovirus B19 infection which took place in a 26-year-old woman despite the evidence for pre-existing anti-B19 IgG antibodies.

STUDY DESIGN

A nested-PCR assay for parvovirus B19 DNA was performed on maternal and fetal samples. Blood samples were tested by various enzyme immunoassays (EIA) for the presence of both anti-B19 IgM and IgG antibodies.

RESULTS

B19 DNA together with anti-B19 IgG antibody were detected in maternal blood at the time of intrauterine fetal demise. Amniotic fluid, chorionic villi and various fetal tissues also tested positive for viral DNA. In retrospect, presence of anti-B19 IgG antibody, but no viral DNA, was repeatedly demonstrated in maternal blood before infection took place. However, the serological results differed with the test system used.

CONCLUSIONS

Provided that the positive serological results are reliable, the presence of anti-B19 IgG in blood samples collected as early as four years before pregnancy neither protected the mother from reinfection not the fetus from transplacental infection with B19 virus. However, discrepant (negative) serological results were also obtained depending on the test system used. Therefore, and in the light of the possible severe consequences of B19-infection during pregnancy, the means for assessment of the significance of anti-B19 titers have to be urgently established by development of both qualitative and quantitative anti-B19 IgM and IgG standards.

Standard curves of cerebral Doppler flow velocity waveforms and predictive values for intrauterine growth retardation and fetal acidosis

Cerebral Doppler measurements seem to be a future method to evaluate the degree of fetal hypoxemia. The aim of this study was (1) to elaborate standard curves for the different cerebral vessels in our own population, and (2) to describe the predictive value of Doppler measurements for intrauterine growth retardation (IUGR) and fetal acidosis. We recorded cerebral flow velocity waveforms from 71 normal pregnancies to establish standard curves for the following vessels: proximal middle cerebral artery, distal middle cerebral artery and posterior cerebral artery. Finally, we calculated the cerebroplacentar index (CPI) for each case. The predictive values from the different vessels were determined in 24 patients with IUGR and 17 cases with fetal acidosis. The poor sensitivity and the low positive predictive value of each cerebral vessel is probably explained by the rather long interval between the last Doppler assessment and delivery (22 +/- 23 days). Reducing the interval to less than 7 days, the distal middle cerebral artery and the CPI were pathological in 4 cases out of 5 fetuses that underwent cesarean section for fetal distress. These latter results have encouraged us to use cerebral Doppler flow velocity to detect fetal hypoxemia. In conclusion, the middle cerebral artery blood flow in its distal part seems to be the finest parameter to predict fetal acidosis, and this vessel should be used to optimize obstetrical management of high-risk pregnancies.