'Site of contact genotoxicity' assessment for implants - Potential use of single cell gel electrophoresis in biocompatibility testing of medical devices.

Toxicological risk assessment of medical devices requires genotoxicity assessment as per ISO 10993, Part 3, which is designed to address gene mutations, clastogenicity and/or aneugenicity endpoints. 'Site of contact genotoxicity' is a potential genotoxic risk especially for medical implants, that is currently not addressed in biocompatibility standards. We therefore performed initial validation study on the use of alkaline single cell gel electrophoresis (comet assay) for detecting 'site of contact genotoxicity' of medical devices, using test items made of acrylic implants impregnated with ethyl methanesulphonate (EMS). Comet assay detected increased DNA migration at the site of implantation, but not in the liver. The same implants also failed to show any genotoxicity potentials, when tested on the standard test battery using Salmonella/microsome and chromosome aberration assays. The study suggested that some medical implants can cause 'site of contact genotoxicity', without producing systemic genotoxicity. In conclusion, comet assay will add new dimension to safety assessment of medical devices, and this assay can be added to the battery of genetic toxicology tests for evaluating biocompatibility of medical implants.

Coil embolization of intracranial aneurysm in polyarteritis nodosa. A case report and review of the literature.

Polyarteritis nodosa (PAN) is a rare multisystem disease characterized by systemic necrotizing arteritis of small and medium size arteries. The skin, joints, kidneys, gastrointestinal tract and peripheral nerves are most commonly involved. Although aneurysms are commonly seen in the visceral vessels, intracranial aneurysms are rare with 15 reported cases. The intracranial aneurysms are usually multiple and located in supra- as well as infra-tentorial compartments. Most of the cases presented with subarachnoid or parenchymal hemorrhage. The aneurysms were usually small, although large cavernous aneurysms were reported in one case. Treatment guidelines are not clear regarding the management of these cases. Most patients were treated conservatively by medical management with surgical excision performed in only two cases and coiling done in one patient with cavernous aneurysms. Repeat hemorrhages or re-bleed in spite of medical treatment have also been reported. We describe the case of a 22-year-old woman, a known case of PAN who presented with subarachnoid hemorrhage. Cerebral angiogram showed a ruptured right middle cerebral artery bifurcation aneurysm along with unruptured left middle cerebral, right posterior communicating and left posterior inferior cerebellar artery aneurysms. Her previous abdominal angiogram had revealed multiple aneurysms in visceral arteries. Successful coil embolization of the ruptured right MCA bifurcation aneurysm was performed with preservation of the parent vessel. The patient made a complete recovery and was placed on medical treatment for PAN. Follow-up MR angiography at three months revealed stable occlusion of the embolized aneurysm with no change in the unruptured aneurysms. Although rare, PAN can be associated with intracranial aneurysms which can cause subarachnoid or parenchymal hemorrhage. Selected cases can be treated safely by coil embolization.

Assessment of DNA damage in sperm after repeated non-invasive sampling in zebrafish Danio rerio.

Repeated non-invasive sampling of zebrafish Danio rerio sperm was conducted, sperm counts were obtained and a method for measurement of DNA damage in sperm was developed and validated (single-cell gel electrophoresis, comet, assay). DNA damage in sperm increased with concentration of hydrogen peroxide (H2 O2 , 0-200 µM), and in vitro exposure of sperm to 200 µM H2 O2 produced 88·7 ± 3·9% tail DNA compared to unexposed controls [12 ± 0·7% tail DNA (mean ± s.e., n = 3)]. Frequency of sperm sampling (sampled every 2, 4 or 7 days) did not affect DNA damage in sperm, but sperm counts decreased 57 and 22% for fish sampled every 2 or 4 days, respectively.

Bioavailability of co-supplemented organic and inorganic zinc and selenium sources in a white fishmeal-based rainbow trout (Oncorhynchus mykiss) diet.

The bioavailability of trace elements in fishmeal diets is influenced by their chemical forms and dietary anti-nutritional factors. In formulated fish feed, supplemented organically bound minerals may be more bioavailable than inorganic minerals. A 10-week feeding trial was undertaken with rainbow trout (Oncorhynchus mykiss) to determine whether the inclusion of organically bound selenium (Se) and zinc (Zn) improved uptake and assimilation of these elements compared to commonly used inorganic forms. The three diets tested included a control diet, no added Zn or Se; an organic Se-yeast and Zn-proteinate supplemented diet; and an inorganic sodium selenite and Zn-sulphate supplemented diet. The endpoints tested were apparent digestibility, whole body levels, tissue distribution and Se- and Zn-dependent enzyme activities. Digestibility of residual Se in the basal diet was 54.2 +/- 1.0% and supplemented Se-yeast was significantly more digestible than selenite (p < 0.05). Digestibility of residual Zn was 21.9 +/- 2.0% and no significant difference was found between the treatments (p = 0.89). Whole body Se was raised by both Se sources and to a greatest extent by Se-yeast (p < 0.001). Zn-sulphate, and to a lesser extent Zn-proteinate, both raised whole body Zn (p < 0.05). Dietary Zn in the basal diet was found to be above requirements, yet Zn-sulphate had a significantly greater retention than Zn-proteinate in those tissues that responded to Zn supplementation. Se-yeast significantly raised Se in all tissues to a greater extent than selenite, except in the pyloric caeca and liver where the greatest increases were by selenite. Only Se-yeast elevated Se-dependent thioredoxin reductase activity (p < 0.05) and neither forms of Se affected glutathione peroxidise activity (p = 0.059). Alkaline phosphatase and carboxypeptidase B were not affected by Zn supplementation (p = 0.51 and p = 0.88 respectively). In all aspects, Se-yeast was found to be a highly bioavailable form of Se in comparison to selenite. Because of its superior bioavailability, organically bound Se would be a preferred Se source for supplementation of fishmeal trout diets than selenite.

Coil embolization of very small (2 mm or smaller) berry aneurysms: feasibility and technical issues.

BACKGROUND AND PURPOSE: The very small size of cerebral aneurysms is considered to be one of the limitations for endovascular treatment, with a high risk for intraoperative rupture. We report on treatment of very small saccular ruptured cerebral aneurysms by coil embolization. All the cases were of 2-mm aneurysms with at least 1 of the dimensions being less than 2 mm. MATERIALS AND METHODS: We performed retrospective analysis of 7 consecutive cases of very small aneurysms treated by coil embolization in our institution between July 2006 and April 2008. RESULTS: 3D rotational angiography (3DRA) was found to be most accurate in the detection of these aneurysms; in 2 cases, 3DRA revealed the aneurysms after results on digital subtraction angiography (DSA) were considered to be negative. Coil embolization was successfully performed in 6 cases, whereas in 1 case, spontaneous thrombosis occurred after microcatheter placement. Complete (n = 5) or near complete (n = 2) immediate occlusion was seen. A single soft coil was used in all cases with the shortest available length. Balloon assistance was used in 3 cases. Although minimal coil projection in the parent vessel was seen in 3 cases, no untoward clinical complication was seen. Follow-up DSA and MR angiography in 4 patients demonstrated persistent occlusion (n = 3) or progressive thrombosis (n = 1) of the aneurysms. All of the patients with available follow-up are independent in day-to-day activities with a modified Rankin Score (mRS) of 0 or 1. CONCLUSIONS: Coil embolization of very small ruptured cerebral aneurysms is feasible. Careful consideration of the technical issues in treatment of these cases is essential to achieve technical success while avoiding complications.

Use of CT angiography for anatomic localization of arteriovenous malformation Nidal components.

We report a case of diffuse arteriovenous malformation (AVM) in basal ganglia and an internal capsule associated with venous aneurysms. The patient was treated by embolization guided by CT angiography to target the basal ganglionic portion of the AVM while sparing the internal capsule. Our case demonstrates that it is possible to obtain good quality intranidal angiograms by using CT angiography, which can be useful for exact localization of the catheterized part of the nidus.

Intraoperative high field magnetic resonance imaging in neurosurgery: our initial experience with the brain suite.

We present our initial experience with the high field (1.5T) intra-operative magnetic resonance imaging, the operating room set-up, our initial cases, the difficulties we faced and how this tool affected a change in the surgical strategy intra-operatively and finally our results. 11 patients were operated on from June 1st to August 1st 2006 of which there were astrocytomas (7), pituitary adenoma (1), craniopharyngioma (1) and meningiomas (2) Localization and lesion targeting were accurate, intra-operative imaging helped to assess the resection volumes, enable corrections for brain shift, perform further tumor resection at the same sitting and help preserve eloquent cortical areas. Gliomas formed 63.6% of the tumors operated on and in 71.4% of these, our surgical strategy changed intra-operatively. Meningiomas formed 9.1% of the tumors operated and image guidance enabled a minimally invasive approach, although no change in our surgical plan was required. One pituitary adenoma and a craniopharyngioma were also operated on with good outcome.

Fitness parameters and DNA effects are sensitive indicators of copper-induced toxicity in Daphnia magna.

This study compared the effects occurring at molecular and population levels in Daphnia magna exposed to copper concentrations in the range of 15-120 microg/l. The qualitative and quantitative modifications arising in random amplified polymorphic DNA (RAPD) profiles as a measure of DNA effects were compared with a number of key ecological fitness parameters, namely, the age-specific survival, age-specific fecundity, net reproductive rate, and intrinsic rate of population increase. Results suggested that growth, reproduction, and most of the fitness parameters as well as genomic template stability (a qualitative measure reflecting changes in RAPD profiles) were significantly affected at copper concentrations of 90 and 120 microg/l. Among the fitness parameters, the age-specific fecundity and net reproductive rate were the most sensitive parameters of toxicity. Changes in RAPD patterns generally occurred at copper concentrations of 90 and 120 microg/l, but with one primer, changes significantly arose at all copper concentrations. Overall, molecular and population parameters compared well and represented a sensitive means to measure toxicity induced by copper in Daphnia magna. In conclusion, the measurement of parameters at both molecular and population levels is valuable for investigating the specific effects of agents interacting with DNA. Ultimately, this methodology may allow the ecotoxicological examination of the link between molecular alterations and measurable adverse effects at higher levels of biological organization.

Tributyltin induces cytogenetic damage in the early life stages of the marine mussel, Mytilus edulis.

Using an integrated approach, the genotoxic potential of bis(tri-n-butyltin), an antifouling agent known to disrupt endocrine system in marine invertebrates, has been evaluated in the embryo-larval stages of the edible mussel, Mytilus edulis. While evaluating the genotoxic potential, the toxicity of tributyltin was also taken into account by determining the maximum tolerated dose. The study suggested that tributyltin is capable of inducing cytogenetic damage (sister chromatid exchanges and chromosomal aberrations) in this target species. The study emphasises the need for further investigations of the potential genotoxic effects of this and other endocrine disrupters on ecologically relevant aquatic invertebrates, which contribute to the maintenance of ecosystems and that could potentially be harmful to human health via the food chain.

Detection of genotoxins in the marine environment: adoption and evaluation of an integrated approach using the embryo-larval stages of the marine mussel, Mytilus edulis.

In genetic ecotoxicology or eco-genotoxicology, there is lack of well-validated systems which could demonstrate the utility of multiple endpoints in environmental quality assessment. For an evaluation of genotoxic potential of heterogeneous marine sediment samples collected from a small fishing harbour in the UK, an in vivo test system using embryo-larval stages of the common mussel, Mytilus edulis was validated against direct and indirect acting reference mutagens. The system appeared to be sensitive and reproducible for cytogenetic endpoints analysed (sister chromatid exchanges (SCEs) and chromosomal aberrations (CAbs)). Following validation and chemical characterisation of the environmental samples, multiple endpoints were measured. Determination of the maximum tolerated dose (MTD) was carried out as a measure to determine cytotoxic effects as a confounding factor for genotoxicity, based on developmental and cytotoxic (in terms of proliferative rate index or PRI) effects. Evaluation of the genotoxic potential of the samples gave a positive response for all the endpoints tested, linking different levels of biological organisation (i.e., chromosomal, cellular and organismal) for the observed effects. The study also emphasises the need for the assessment of the short and long-term impacts of dredge disposal on marine biota by including laboratory-based bioassays and incorporating an integrated approach which could yield as much useful information as possible in overall hazard and risk assessment for aquatic genotoxicity.

Primary fibrosarcoma of brain.

This is a case presentation of a young patient with an intracranial space-occupying lesion following multiple episodes of generalised tonic clonic seizures for the last 20 years. Such a long latency period between the onset of fits and the discovery of an intracranial lesion is highly unusual in malignant brain tumours. This lesion was excised completely and proved to be a primary lesion of the brain - fibrosarcoma. These rare tumours of mesenchymal origin in the central nervous system are very rare.

Genotoxic, cytotoxic and developmental effects of tributyltin oxide (TBTO): an integrated approach to the evaluation of the relative sensitivities of two marine species.

Adopting an integrated approach the potential genotoxic, cytotoxic and developmental effects of tributyltin oxide (TBTO), a known endocrine-disrupting agent for neogastropods, have been evaluated in two ecologically relevant invertebrates: Mytilus edulis (blue mussel) and Platynereis dumerilli (rag worm). Following determination of the maximum tolerated dose (MTD) in terms of developmental and survival effects, the embryo-larval stages of these organisms were exposed to a range of concentrations of TBTO, and analysed for cytotoxic (proliferation rate index) and genotoxic (sister chromatid exchanges and chromosomal aberrations) effects. The study suggested that: (1) TBTO is both toxic and genotoxic to embryo-larval stages of both species; (2) at comparable concentrations, for developmental and genotoxic effects, P. dumerilii (non-target species) is more sensitive compared to M. edulis (target species); and (3) genotoxic effects are more closely tied with the development and survival of the organisms. The study emphasises the need of the evaluation of genotoxic potential of other endocrine-disrupting agents in different taxonomic groups.

Assessment of developmental effects, cytotoxicity and genotoxicity in the marine polychaete (Platynereis dumerilii) exposed to disinfected municipal sewage effluent.

While sodium hypochlorite is widely used as a disinfectant for municipal sewage effluents and power station cooling waters discharged into coastal environments, there is limited information on the potential in vivo genotoxicity of such disinfection procedures to marine organisms. Using a recently developed test system based on the marine polychaete Platynereis dumerilii, we have evaluated impacts based on embryo-larval development, cytotoxicity and genotoxicity following exposure to disinfected settled (primary) effluent from a municipal sewage treatment works (STW). Sewage samples were collected from Newton Abbot STW, Devon, UK and then disinfected with sodium hypochlorite based on standard operational procedures. Exposure of polychaetes to dilutions of disinfected sewage in seawater (20 +/- 1 degree C) led to a marked reduction in normal embryo-larval development (7 h EC50 from 0.57-1.88% (v/v), n = 4), with a simultaneous increase in cytotoxicity. Following the calculation of the Maximum Tolerated Dose (MTD), based on developmental and cytotoxic effects, the organisms were also analysed for the induction of chromosomal aberrations. This investigation demonstrated the absence of genotoxicity in polychaetes exposed in vivo to sewage disinfected with sodium hypochlorite. These observations extend our previously published studies in which polychaetes exposed to non-disinfected sewage, while showing developmental toxicity and cytotoxicity, did not exhibit any evidence of cytogenetic damage.

A simple technique to limit ICP catheter infection.

Infection of intracranial catheters is a common complication of ICP monitoring. The introduction of a simple technique of ensheathing the entire length of the external segment of the catheter in a sterile plastic sheath resulted in a decreased infection rate. In the study year, one of 78 patients developed catheter-induced meningitis, compared with seven of 64 patients in the year prior to the introduction of the protective plastic sheath. The use of a plastic sheath resulted in a low rate of infection.

Evaluation of the genotoxicity of municipal sewage effluent using the marine worm Platynereis dumerilii (Polychaeta: Nereidae).

Samples of settled (primary) effluent were collected from a municipal sewage treatment works at Newton Abbot, Devon, UK, a site which discharges primary effluent via long sea pipeline into the English Channel (minimum of 200-fold initial dilution). Sewage samples were collected during the period February-April 1995 and were analysed for standard physico-chemical parameters (ammonia, chemical oxygen demand, conductivity, non-purgeable organic carbon and settled solids). Samples were also tested for cytotoxicity, genotoxicity, and for developmental effects in the embryo-larval stages of the marine worm, Platynereis dumerilii. Exposure to sewage concentrations of > or = 10% (v/v) in seawater at 20 +/- 1 degrees C led to a marked reduction in normal embryo-larval development (7 h EC50 values from 10% to 18% v/v, n = 5). There was also evidence of a simultaneous delay in the cell cycle progression (as determined by sister chromatid differential staining) following embryo-larval exposures to sewage concentrations of > or = 10% (v/v). Following the calculation of the Maximum Tolerated Dose (MTD), based on cytotoxic and developmental effects, cells from the same embryo-larvae were analysed for chromosomal aberrations (CAs). Results were consistent for all samples tested, demonstrating the absence of cytogenetic damage following the in vivo exposure of polychaete embryo-larvae to settled sewage.

Simultaneous lumbar and intraventricular manometry to evaluate the role and safety of lumbar puncture in raised intracranial pressure following subarachnoid haemorrhage.

We report a prospective investigation of a bedside test to evaluate the role and safety of lumbar puncture in raised intracranial pressure in patients with subarachnoid haemorrhage. Fourteen patients who underwent aneurysm clipping following subarachnoid haemorrhage were studied. All patients had intraventricular drains and needed high volume cerebrospinal fluid (CSF) drainage to maintain the normal intracranial pressure. A lumbar puncture was performed in these patients and the simultaneous opening lumbar and ventricular pressures noted, CSF was then drained via the lumbar puncture, and the simultaneous closing lumbar and ventricular pressures noted. In all patients, the opening lumbar pressure was close to the ventricular pressure. In 13 of 14 patients, CSF drainage resulted in an equivalent and simultaneous fall of ventricular pressure. We concluded that simultaneous measurement of lumbar and ventricular CSF pressure before and after lumbar CSF drainage allows identification of candidates with differential cranial and lumbar pressures and therefore indicates safety or risk of lumbar CSF drainage.