Trace determination of fluoroquinolone antibacterial agents in urban wastewater by solid-phase extraction and liquid chromatography with fluorescence detection

Fluoroquinolones (FQs) are among the most important antibacterial agents (synthetic antibiotics) used in human and veterinary medicine. An analytical method based on reversed-phase liquid chromatography with fluorescence detection was developed and validated for the simultaneous determination of nine FQs and the quinolone pipemidic acid in urban wastewater. Aqueous samples were extracted using mixed-phase cation-exchange disk cartridges that were subsequently eluted by ammonia solution in methanol. Recoveries were above 80% at an overall precision of better than 10%. Instrumental quantification limits varied between 150 and 450 pg injected. The presented method was successfully applied to quantify FQs in effluents of urban wastewater treatment plants. The two most abundant human-use FQs, ciprofloxacin and norfloxacin, occurred in primary and tertiary waste-water effluents at concentrations between 249 and 405 ng/L and from 45 to 120 ng/L, respectively. The identity of FQs in urban wastewater was confirmed by recording full fluorescence spectra and liquid chromatography directly coupled to tandem mass spectrometry. These results indicate that conventional environmental risk assessment overestimates FQ concentrations in surface waters by 1 to 2 orders of magnitude.

Reduction of left ventricular mass by lisinopril and nifedipine in hypertensive renal transplant recipients: a prospective randomized double-blind study

BACKGROUND

Cardiovascular disease is the dominant cause of death in renal transplant recipients. Left ventricular hypertrophy (LVH) is a known risk factor. After renal transplantation, persistent hypertension is an important determinant for the further evolution of LVH. The aim of the present study was to compare the effect of an angiotensin converting enzyme (ACE) inhibitor (lisinopril) with a calcium channel blocker (CCB) (controlled release nifedipine) in treatment of posttransplant hypertension focusing on changes in LVH.

METHODS

One hundred fifty-four renal transplant recipients presenting with hypertension (diastolic BP> or =95 mmHg) during the first 3 weeks after transplantation were randomized to receive double-blind 30 mg nifedipine or 10 mg lisinopril once daily.

RESULTS

One hundred twenty-three patients completed 1 year of treatment. Good quality echocardiographic data were available in 116 recipients (62 nifedipine/54 lisinopril) 2 and 12 months posttransplant. Blood pressure was equally well controlled in the two groups throughout the study (mean systolic/diastolic+/-SD after 1 year: 140+/-16/87+/-8 mmHg with nifedipine and 136+/-17/85+/-8 mmHg with lisinopril). Left ventricular mass index was reduced by 15% (P<0.001) in both groups (from 153+/-43 to 131+/-38 g/m2 with nifedipine and from 142+/-35 to 121+/-34 g/m2 with lisinopril). There were no statistically significant differences between the two treatment groups at baseline or at follow-up.

CONCLUSIONS

In hypertensive renal transplant recipients with well-controlled blood pressure, there is a regression of left ventricular mass after renal transplantation. The regression of left ventricular mass index is observed to a similar extent in patients treated with lisinopril or nifedipine.

Laser microdissection and microsatellite analyses of breast cancer reveal a high degree of tumor heterogeneity

Carcinomas with productive fibrosis are the most common forms of breast cancer. Analysis of tumor-specific genomic alterations can be compromised by the presence of normal cells, demanding microdissection of small tumor areas to detect loss of heterozygosity (LOH) and microsatellite instability (MSI). The aim of this study was to evaluate the importance of precise laser microdissection for microsatellite analyses and investigation of tumor heterogeneity in breast cancer. 39 primary breast tumor samples were analyzed for MSI and LOH by PCR followed by polyacrylamide gel electrophoresis and silver staining using 15 microsatellite markers. Different tumor areas were processed separately in 30 patients. Both intraductal and invasive breast cancer regions were investigated in 11 patients. The following results were obtained: (1) accurate microdissection revealed MSI in 3 or more of the investigated markers (> or =20%) in 33% of the patients, a higher frequency than reported previously; (2) laser microdissection was 43% more sensitive in detection of LOH compared to manual microdissection due to a reduction of contamination by normal cells, and (3) 29 of 30 investigated tumors showed heterogeneity of genetic alterations in different tumor regions. Laser-based microdissection is a valuable tool in genetic analysis of desmoplastic tumors and allows an accurate determination of genetic alterations in histologically different tumor regions.

Microsatellite instability in tumor and nonneoplastic colorectal cells from hereditary non-polyposis colorectal cancer and sporadic high microsatellite-instable tumor patients

Genetic alterations such as loss of heterozygosity (LOH) and microsatellite instability (MSI) have been frequently studied in various tumor types. Genetic heterogeneity of nonneoplastic cells has not yet been sufficiently investigated. However, genomic instability in normal cells could be a potentially important issue, in particular when these cells are used as reference in LOH and MSI analyses of tumor samples. In order to investigate possible genetic abnormalities in normal colorectal cells of tumor patients, MSI analyses of normal colonic mucosa were performed. Up to 15 different laser-microdissected normal regions containing 50-150 cells were investigated in each of 15 individual microsatellite-stable, sporadic high microsatellite-instable (MSI-H) and hereditary non-polyposis coli cancer (HNPCC) colorectal cancer patients. Frequent MSI and heterogeneity in the MSI pattern were found both in normal and tumor cells from 10 HNPCC and sporadic MSI-H tumor patients whose tumors had defect mismatch repair protein expressions. This observation shows that MSI can also occur in nonneoplastic cells which has to be considered in MSI analyses for molecular HNPCC screening. In addition, considerable genetic heterogeneity was detected in all MSI-H (sporadic and HNPCC) tumors when analyzing five different regions with less than 150 cells, respectively. These differences were not detectable in larger tumor regions containing about 10,000 cells. Thus, heterogeneity of the MSI pattern (e.g. intratumoral MSI) is an important feature of tumors with the MSI-H phenotype.

Oligoclonality of early lesions of the urothelium as determined by microdissection-supported genetic analysis

AIM

To contribute to the ongoing discussion of clonality of human urothelial cancer it was considered a valuable approach to analyze multiple areas from cystectomy specimens for deletions of chromosomes known to be involved early in bladder cancer development.

MATERIAL AND METHODS

Thus, in 86 biopsies of 4 human cystectomies with different histological findings (maximal diagnosis: pT1G2, pTaG3, pT2G2, normal) loss of heterozygosity (LOH) was investigated as a deletion marker using markers of chromosomes 8p, 9p, 9q and 17p. Findings were compared to histology of the lesion.

RESULTS

Findings indicate: (1) no changes in the markers investigated in the bladder with histologically normal urothelium in contrast to detection of LOH in normal urothelium of tumour-bearing bladders; (2) an accumulation of the number of LOH with increasing malignancy of lesions within one bladder, and (3) indications of oligoclonal neoplastic lesions in two of the urinary bladders investigated.

CONCLUSIONS

The investigation of multiple lesions within one bladder presents a snapshot of genetic changes in differently advanced tumour stages. The hypotheses of tumour evolution and oligoclonality as derived from our LOH data need to be supported by deletion-independent clonality studies as X-chromosomal inactivation analysis.

Isolation and characterisation of new Gram-negative and Gram-positive atrazine degrading bacteria from different French soils

The capacity of 12 soils to degrade atrazine was studied in laboratory incubations using radiolabelled atrazine. Eight soils showed enhanced degradation of this compound. Twenty-five bacterial strains able to degrade atrazine were isolated by an enrichment method from 10 of these soils. These soils were chosen for their wide range of physico-chemical characteristics. Their history of treatment with atrazine was also variable. The genetic diversity of atrazine degraders was determined by amplified ribosomal restriction analysis (ARDRA) of the 16S rDNA gene with three restriction endonucleases. The 25 bacterial strains were grouped into five ARDRA types. By sequencing and aligning the 16S rDNA genes, the isolates were shown to belong to the Gram-negative species Chelatobacter heintzii, Aminobacter aminovorans, Stenotrophomonas maltophilia and to the Gram-positive genus Arthrobacter crystallopoietes. These species were not described previously as being capable of atrazine degradation. Most Gram-negative bacteria could mineralise (14)C ring labelled atrazine and carried the atzA, atzB, atzC and trzD genes. Gram-positive strains could convert atrazine to cyanuric acid and carried only the atzB and atzC genes. In this study, we describe the atrazine degradation capacities and corresponding genes in bacterial species that were not known as atrazine degraders. We report for the first time the occurrence of the trzD gene in these atrazine-mineralising bacteria and we demonstrate the potential use of colony hybridisation to isolate bacteria involved in atrazine degradation.

Better microvascular function on long-term treatment with lisinopril than with nifedipine in renal transplant recipients

BACKGROUND

The prevalence of hypertension in renal transplant recipients is high but the pathophysiology is poorly defined. Impaired endothelial function may be a factor of major importance. The present study addresses the effects of long-term treatment with either lisinopril or slow-release nifedipine on microvascular function and plasma endothelin in renal transplant recipients on cyclosporin A (CsA).

METHODS

Seventy-five hypertensive renal transplant recipients were double-blind randomized to receive slow-release nifedipine (NIF, n=40) or lisinopril (LIS, n=35). Ten normotensive, age-matched recipients served as controls. All patients received CsA-based immunosuppressive therapy including prednisolone and azathioprine. Microvascular function was assessed in the forearm skin vasculature, using laser Doppler flowmetry in combination with post-occlusive reactive hyperaemia and endothelial-dependent function during local acetylcholine (ACh) stimulation.

RESULTS

The analysis of microvascular function (AUC(rh)) showed that nifedipine-treated patients had significantly lower responses compared with lisinopril-treated patients (20+/-17 and 43+/-20 AU x min respectively, P=0.0016). Endothelial function was borderline significantly lower in the NIF group compared with the LIS group (640+/-345 and 817+/-404 AU x min respectively, P=0.056). The responses in the LIS group were comparable with those in non-hypertensive controls (AUC(rh) was 37+/-16 and AUC(ACh) was 994+/-566 AU x min). Plasma endothelin-1 concentrations were significantly higher in the NIF group compared with the LIS group (0.44+/-0.19 vs. 0.34+/-0.10 fmol/ml respectively, P=0.048), and were 0.29+/-0.09 fmol/ml in the control patients. AUC(ACh) was associated with plasma endothelin-1 (P=0.0053), while AUC(rh) was not (P=0.080).

CONCLUSIONS

The study indicates that long-term treatment with lisinopril, when compared with nifedipine, yields a more beneficial effect on microvascular function in hypertensive renal transplant recipients on CsA. The beneficial microvascular effect may be mediated in part by an endothelin-1-associated effect on the endothelium.

[Acute renal failure caused by hypercalcemia]

BACKGROUND

Hypercalcaemia may cause acute renal failure.

MATERIAL AND METHODS

We present and discuss two patients with acute renal failure caused by hypercalcaemia.

RESULTS

Patient no. 1 was treated with too high doses of vitamin D for hypoparathyroidism. Patient no. 2 had been taking extremely high doses of calcium carbonate for dyspeptic pain. Volume depletion and renal vasoconstriction are the mechanisms that lead to acute renal failure. Long-lasting hypercalcaemia will lead to calcium deposits in the kidneys (nephrocalcinosis), which is known to cause chronic renal failure.

INTERPRETATION

It is mandatory to start early treatment for serious hypercalcaemia. If treatment is started in time, the renal failure may be reversible. Constant vigilance is essential when patients are treated with vitamin D.

Seizures in cerebral arteriovenous malformations: type, clinical course, and medical management

SUMMARY

We investigated the type and early clinical course of seizure disorders in cerebral arteriovenous malformations (AVMs). Decisions on invasive treatment for AVMs depend on detailed knowledge of the natural course and prognosis of neurologic sequelae. Among 328 patients of a prospective cerebral AVM databank 92 (28%) presented with seizures unrelated to haemorrhage. Under a median observation time of 2.2 years (mean 3.8 years) the 92 patients received 454 follow-up examinations (median time interval 4.6 months). All patients were treated with anticonvulsant medication. During the observation period sixty (65%) patients received staged endovascular glue embolisation. The effect of staged embolisation on seizure recurrence was tested univariately by comparing patients undergoing embolisation versus those without endovascular treatment. At the time of enrolment in the database, elementary (motor or sensory) and partial complex seizures were described in twenty (22 %) and one (1%) patients, respectively. Generalized seizures without focal initiation were reported in sixty (65%) and with focal initiation in 11 (12%) patients. 57 (62%) cases had suffered a seizure as a first single event, ten (11%) had weekly, 17 (19%) monthly, and eight (9%) patients had seizures once per year. In the following clinical course, complete cessation of seizure activity was seen in 69 (75%). Ten (11%) patients continued to have seizures at a rate of once per year or less. 13 (14%) cases continued to have weekly to monthly events with only four (4%) of them showing (monthly) grand mal. An early beneficial effect of staged embolisation on seizure recurrence was not observed. Seizure disorders in cerebral AVMs show a benign early course, leaving few patients with insufficient seizure control. The differential longterm effect of invasive AVM treatment on seizure control should be subject to clinical trials.

Anticoagulation intensity sufficient for haemodialysis does not prevent activation of coagulation and platelets

BACKGROUND

A single bolus of dalteparin at the start of haemodialysis (HD) may prevent clot formation, but subclinical activation of platelets and coagulation may still occur. Consequently, the relationship between clinical clotting events and activation markers of platelets and coagulation before and during HD is of interest.

METHODS

The effect of tapered doses of dalteparin during 84 HD sessions (4-4.5 h) was prospectively examined in 12 patients. Six of the patients were treated with warfarin. The initial dalteparin dose was reduced to 50% if no clotting was observed. Clinical clotting was evaluated by inspection of the air trap every hour and by inspection of the dialyser after each session. Anti-FXa activity was measured for assessment of dalteparin activity. Markers of activated plasma coagulation, (thrombin-antithrombin (TAT) and prothrombin fragment 1+2 (PF1+2)) and a marker of platelet activation (beta-thromboglobulin, beta-TG), were measured before the start of and after 3 and 4 h of dialysis. Ten pre-dialytic patients with chronic renal failure served as a control group. A total of 230 measurements of each parameter were performed.

RESULTS

An anti-FXa activity above 0.4 IU/ml at the end of HD inhibits overt clot formation for 4 h. This was obtained by an intravenous dalteparin dose of about 5000 IU. TAT and PF1+2 correlated to clinical clotting episodes (r=0.50 and 0.47, P<0.001). beta-TG was not significantly correlated to clinical clotting. All parameters increased during the sessions (TAT, PF1+2, beta-TG, P<0.001). When measurements during clinical clotting episodes were disregarded, all parameters were still markedly increased. Warfarin-treated patients had lower TAT and PF1+2. Dialysis patients had higher beta-TG values than pre-dialytic patients.

CONCLUSION

Despite clinically effective anticoagulation, obtained by dalteparin administration, platelets and coagulation are activated by HD, resulting in a potentially thrombophilic state. Warfarin treatment reduces clinical clot formation and subclinical activation of coagulation.

Metabolic cardiovascular syndrome after renal transplantation

BACKGROUND

Cardiovascular disease (CVD) is the major cause of death in renal transplant recipients. Traditional risk factors like hypertension, dyslipidaemia and diabetes mellitus are common, but cannot completely account for the high prevalence of CVD in this population. The aim of the present study was to assess whether post-transplant glucose intolerance, defined as post-transplant diabetes mellitus, impaired glucose tolerance, or impaired fasting glucose, is associated with metabolic disturbances known to increase risk of cardiovascular disease, similar to what has been observed in the general population.

METHODS

One hundred and seventy-three consecutive patients were prospectively examined 10 weeks after transplantation. An oral glucose tolerance test was completed in 167 patients. Questionnaires, medical records, and the results of various blood tests were used to evaluate a number of known cardiovascular risk factors in all patients.

RESULTS

Glucose intolerance was present in about one-half the recipients and was associated with age, a positive family history of ischaemic heart disease, acute rejection, higher levels of serum triglycerides, apolipoprotein B and 2-h insulin, and lower levels of serum HDL cholesterol. After adjustment for age and sex, lower HDL cholesterol (P=0.005), higher serum triglycerides (P<0.001), apolipoprotein B (P=0.039) and 2-h insulin (P<0.001) were still associated with post-transplant glucose intolerance.

CONCLUSIONS

Ten weeks after renal transplantation glucose intolerance is associated with a clustering of cardiovascular risk factors and metabolic abnormalities, consistent with a post-transplant metabolic cardiovascular syndrome.

[Acute dialysis-dependent renal failure at the Rikshospital in 1998]

BACKGROUND

There are few epidemiological studies on acute renal failure, and as far as we know none have previously been conducted in Norway. The objective of this study was to evaluate the scope, etiology, treatment and results of dialysis-dependent acute renal failure based on data from the Norwegian National Hospital in 1998.

MATERIAL

This study is based on data from a questionnaire applied to all patients (n = 44) treated with dialysis for acute renal failure at the Norwegian National Hospital in 1998. The questionnaire was designed by a group of Norwegian nephrologists in cooperation with the Norwegian Society of Nephrology.

RESULTS

The incidence of dialysis-dependent acute renal failure was 54.4 per million population. Men constituted 75% of the patient population. The most common underlying disorders were heart disease, peripheral vascular disease, and cancer. 90% of patients had oliguric acute renal failure, most frequently due to postoperative complications, septicaemia or drugs, and in most cases the aetiology was multifactorial. Patients received on average nine intermittent hemodialysis treatments and stayed on average ten days in the intensive care unit. 30% of the patients were either heart, lung, liver or bone marrow transplanted (renal transplant patients were excluded). The 60 day mortality rate was 41%.

INTERPRETATION

The incidence of dialysis-dependent acute renal failure was relatively high in the Norwegian National Hospital patient pool, combined with a significant mortality rate. These findings are comparable with those of other studies.

Parkin immunoreactivity in the brain of human and non-human primates: an immunohistochemical analysis in normal conditions and in Parkinsonian syndromes

The etiology of Parkinson's disease is unknown, but the gene involved in an autosomic recessive form of the disease with early onset has recently been identified. It codes for a protein with an unknown function called parkin. In the present study we produced a specific polyclonal antiserum against human parkin. Immunohistochemical analysis showed that parkin is expressed in neuronal perikarya and processes but also in glial and blood vessels in the primate brain (human and monkey). Electron microscopy indicated that parkin immunoreactivity is mostly located in large cytoplasmic vesicles and at the level of the endoplasmic reticulum. Parkin was expressed heterogeneously in various structures of the brain. It was detectable in the dopaminergic systems at the level of the perikarya in the mesencephalon but also in the striatum. However, parkin was also expressed by numerous nondopaminergic neurons. The staining intensity of parkin was particularly high in the hippocampal formation, the pallidal complex, the red nucleus, and the cerebellum. Comparison of control subjects with patients with Parkinson's disease and control animals with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated animals revealed a loss of parkin-immunoreactive neurons only in the substantia nigra pars compacta. Furthermore, the surviving dopaminergic neurons in the parkinsonian state continued to express parkin at a level similar to that observed in the control situation. These data indicate that parkin is a widely expressed protein. Thus, the degeneration of dopaminergic neurons in familial cases of Parkinson's disease with autosomal recessive transmission cannot be explained solely in terms of an alteration of this protein.

Effects of fluvastatin on cardiac events in renal transplant patients: ALERT (Assessment of Lescol in Renal Transplantation) study design and baseline data

BACKGROUND

Recent clinical trials of primary and secondary prevention of cardiovascular disease have demonstrated that lowering plasma cholesterol with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors ('statins') reduces morbidity and mortality from coronary heart disease in diverse patient populations.

STUDY AIMS

The aim of the present ALERT (Assessment of Lescol in Renal Transplantation) study is to determine whether renal transplant recipients would also benefit from statin therapy. ALERT is a multicentre, randomized, double-blind, placebo-controlled trial to assess the effect of fluvastatin in renal transplant recipients with mild-to-moderate hypercholesterolaemia. The primary objective is to investigate the effects of fluvastatin on major adverse cardiac events (MACE). In addition, the effects on cardiovascular and all-cause mortality, as well as renal function, will be addressed.

STUDY POPULATION

The study population contains patients with functioning renal allografts of more than 6 months' duration, recruited from 75 centres in Northern Europe and Canada. Patients of both sexes, aged 30-75 years, with a total cholesterol level of 4.0-9.0 mmol/l (155-348 mg/dl) were included, except for those with a history of myocardial infarction, where the upper limit for inclusion was 7.0 mmol/l (270 mg/dl).

STUDY DESIGN

A total of 2100 patients were recruited by the end of October 1997 and will be followed for up to 6 years. This report presents the design features of the study (recruitment, follow-up, sample size, data analysis and study organization), along with baseline results. ALERT is the first large-scale prospective, randomized, double-blind study to address the prevention of cardiovascular mortality in renal transplant patients receiving an HMGCoA reductase inhibitor.

Tapering off prednisolone and cyclosporin the first year after renal transplantation: the effect on glucose tolerance

BACKGROUND

Glucose intolerance is an untoward side effect of some immunosuppressive and anti-hypertensive drugs. The primary aim of the present prospective observational study was to test the hypothesis that tapering off prednisolone and cyclosporin (CsA) the first year after transplantation may have beneficial effects on glucose tolerance in renal transplant recipients.

METHODS

Ninety-one non-diabetic recipients were included, and 87 patients underwent a 75 g oral glucose tolerance test both 10 weeks and 1 year after renal transplantation. The change over time in 2-h blood glucose was compared with a number of variables potentially influencing glucose tolerance.

RESULTS

The proportion of glucose intolerant recipients was reduced from 55 to 34% during the study. Univariate linear regression analysis showed a significant association between the reduction in daily prednisolone dose down to 5 mg and decline in blood glucose (P=0.001), whereas weight gain was associated with increasing blood glucose (P=0.031). Each 1-mg reduction of prednisolone dose leads to an estimated decline in 2-h blood glucose of 0.12 mmol/l based on the multiple linear regression model (P=0.003). Twelve out of 22 patients with post-transplant diabetes mellitus (PTDM) at baseline improved to normal or impaired glucose tolerance. Ten PTDM-subjects who remained diabetic 1 year after transplantation had lower serum insulin levels during the oral glucose challenge, and five patients treated with anti-diabetic drugs at baseline required hypoglycaemic drugs also at follow up. The decline in CsA level of 100 microg/l and the lower number of patients treated with beta-blockers at follow-up, did not alter glucose tolerance significantly.

CONCLUSIONS

Tapering off prednisolone, but not CsA, significantly improves glucose tolerance during the first year after renal transplantation.

Caspase-8 is an effector in apoptotic death of dopaminergic neurons in Parkinson's disease, but pathway inhibition results in neuronal necrosis

Caspase-8 is a proximal effector protein of the tumor necrosis factor receptor family death pathway. In the present human postmortem study, we observed a significantly higher percentage of dopaminergic (DA) substantia nigra pars compacta neurons that displayed caspase-8 activation in Parkinson's disease (PD) patients compared with controls. In an in vivo experimental PD model, namely subchronically 1,2,3,6-tetrahydropyridine-treated mice, we also show that caspase-8 is indeed activated after exposure to this toxin early in the course of cell demise, suggesting that caspase-8 activation precedes and is not the consequence of cell death. However, cotreatment of 1-methyl-4-phenylpyridinium-intoxicated primary DA cultures with broad-spectrum and specific caspase-8 inhibitors did not result in neuroprotection but seemed to trigger a switch from apoptosis to necrosis. We propose that this effect is related to ATP depletion and suggest that the use of caspase inhibitors in pathologies linked to intracellular energy depletion, such as PD, should be cautiously evaluated.

Design and application of new 16S rRNA-targeted oligonucleotide probes for the Azospirillum-Skermanella-Rhodocista-cluster

The genera Azospirillum, Skermanella and Rhodocista form a phylogenetic subgroup within the alfa subclass of Proteobacteria. Based on comparative 16S rRNA sequence analysis a nested set of new oligonucleotide probes was designed. It comprises probes for the whole genus cluster Azospirillum-Skermanella-Rhodocista, for the Azospirilli subcluster I including A. lipoferum, A. doebereinerae, A. largimobile, A. brasilense and A. halopraeferens, for the Azospirilli subcluster II including A. amazonense, A. irakense and the genus Skermanella, for the genus Rhodocista as well as for all Azospirilli species or species cluster. The new probes allow a fast and reliable in situ identification of bacteria belonging to the Azospirillum-Skermanella-Rhodocista-cluster at different phylogenetic levels. The specificity of the new probes was tested with 56 strains of the Azospirillum-Rhodocista-Skermanella-cluster and selected reference cells from other genera by hybridising with the complete probe set. In addition, applications of the fluorescently labelled probes for in situ identification of isolates and for the in situ localisation of A. brasilense on maize roots were demonstrated using confocal laser scanning microscopy.

Endothelial capillaries chemotactically attract tumour cells

Directional migration of capillaries towards tumour implants is generally assumed to be regulated by chemotaxis. Preliminary evidence has also been presented for the existence of a reverse chemotactic signalling pathway, with capillaries attracting tumour cells via paracrine factors. By using a variety of endothelial cell types and tumour cell lines, this study has systematically investigated chemotaxis between endothelial cells and tumour cells in two- and three-dimensional systems. Checkerboard analysis revealed faint attraction of human umbilical vein endothelial cells (HUVECs), but not porcine aortic endothelial cells (PAECs), by tumour cells. In reverse, both PAECs and HUVECs potently induced chemotactic migration of tumour cells. Using a microcarrier-based fibrin gel assay, directional migration of endothelial cells towards tumour cells was not observed. In reverse, tumour cells were strongly attracted by endothelial cells. Identification of endothelium-derived chemotactic molecules may provide a valuable approach for the treatment of tumour metastasis.

Is Bax a mitochondrial mediator in apoptotic death of dopaminergic neurons in Parkinson's disease?

Bax is a proapoptotic member of the Bcl-2 family of proteins. It is believed to exert its action primarily by facilitating the release of cytochrome c from the mitochondrial intermembrane space into the cytosol, leading to caspase activation and cell death. Because alterations in mitochondrial respiratory function, caspase activation and cell death with morphologic features compatible with apoptosis have been observed post mortem in the brain of patients with Parkinson's disease, we tried to clarify the potential role of Bax in this process in an immunohistochemical study on normal and Parkinson's disease post-mortem brain and primary mesencephalic cell cultures treated with MPP(+). We found that Bax is expressed ubiquitously by dopaminergic (DA) neurons in post-mortem brain of normal and Parkinson's disease subjects as well as in vitro. Using an antibody to Bax inserted into the outer mitochondrial membrane as an index of Bax activation, no significant differences were observed between control and Parkinson's disease subjects, regardless of the mesencephalic subregion analysed. However, in Parkinson's disease subjects, the percentage of Bax-positive melanized SNpc neurons containing Lewy bodies, suggestive of DA neuronal suffering, was significantly higher than the overall percentage of Bax-positive neurons among melanized neurons. Furthermore, all melanized SNpc neurons in Parkinson's disease subjects with activated caspase-3 were also immunoreactive for Bax, suggesting that Bax anchored in the outer mitochondrial membrane of melanized SNpc neurons showing signs of neuronal suffering or apoptosis is increased compared with DA neurons that are apparently unaltered. Surprisingly, MPP(+) treatment of tyrosine hydroxylase (TH)-positive neurons in primary mesencephalic cultures did not cause redistribution of Bax, although cytochrome c was released from the mitochondria and nuclear condensation/fragmentation was induced. Taken together, these findings suggest that in the human pathology, Bax may be a cofactor in caspase activation, but our in vitro data fail to indicate a central role for Bax in apoptotic death of DA neurons in an experimental Parkinson's disease paradigm.

Endothelial capillaries chemotactically attract tumour cells

Directional migration of capillaries towards tumour implants is generally assumed to be regulated by chemotaxis. Preliminary evidence has also been presented for the existence of a reverse chemotactic signalling pathway, with capillaries attracting tumour cells via paracrine factors. By using a variety of endothelial cell types and tumour cell lines, this study has systematically investigated chemotaxis between endothelial cells and tumour cells in two- and three-dimensional systems. Checkerboard analysis revealed faint attraction of human umbilical vein endothelial cells (HUVECs), but not porcine aortic endothelial cells (PAECs), by tumour cells. In reverse, both PAECs and HUVECs potently induced chemotactic migration of tumour cells. Using a microcarrier-based fibrin gel assay, directional migration of endothelial cells towards tumour cells was not observed. In reverse, tumour cells were strongly attracted by endothelial cells. Identification of endothelium-derived chemotactic molecules may provide a valuable approach for the treatment of tumour metastasis.

Automatic analysis of slides processed in the Comet assay

In recent years the Comet assay (or single cell gel electrophoresis assay) has been established as a rapid and sensitive method for the detection of DNA damage. For early genotoxicity screening of new chemical entities in industrial toxicology, the Comet assay is more and more used for assessment of the DNA damaging potential of a test compound. In order to increase compound screening throughput, we have established an image analysis system for fully automated measurement of microscope slides processed in the Comet assay. For the comparative investigation various cell types, such as V79 Chinese hamster cells, mouse lymphoma cells and human leukocytes, were treated with several test compounds. Using tail moment as the quantitative parameter for comet formation, we show a very high correlation between our automatic image analysis system and a commercially available, interactive system (Comet Assay II of Perceptive Instruments). The possibility of analyzing 50 samples within 1 day and the high reproducibility of results make automated image processing a powerful tool for automatic analysis of slides processed in the Comet assay.

Caspase-3 activation in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice

In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models of Parkinson's disease (PD), dopaminergic (DA) neurons have been shown to die by apoptosis. Moreover, recent postmortem and in vitro results have indicated that apoptotic cell death induced by 1-methyl-4-phenylpyridinium (MPP(+)) may be mediated by caspase-3. To establish whether caspase-3 activation may indeed play a role in an in vivo model of PD, we studied caspase-3 activation in C57Bl/6 mice subchronically intoxicated with MPTP. We show that caspase-3 activation peaks early, at days 1 and 2 after the end of MPTP intoxication. In contrast, pycnotic neurons persist until day 7 postintoxication, indicating that caspase-3 activation is an early and transient phenomenon in apoptotic death of DA neurons. We further demonstrate that loss of tyrosine hydroxylase (TH) immunoreactivity in this model is indeed due to cell loss rather than to loss of TH protein expression. We conclude that mice subchronically intoxicated with MPTP represent a valid PD model to study and manipulate caspase activation in vivo.