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H M Fernandes

Publications and source records attributed to H M Fernandes.

14 recordsLinked to original sources
PubMed2005

A comparative assessment of heavy metal accumulation in soft parts and byssus of mussels from subarctic, temperate, subtropical and tropical marine environments.

Existing data on metal concentrations in mussels from subarctic, temperate, subtropical and tropical waters were analyzed using multivariate statistics in order to assess regional variations in metal contamination. Potential errors were reduced by only analyzing data from surveys that employed the same protocols, analytical methodologies and analysts. Factor analysis demonstrated that mussels inhabiting extremely contaminated areas (e.g. from Japanese and Swedish metallurgy sources) could be separated from mussels from other contaminated areas, and that metals such as Cd, Pb, Cu and Zn could be used to identify heavily contaminated samples while Co, Fe, Cr and Ni concentrations were good markers for exposure to inputs from different industrial sources. Furthermore byssus, like soft tissue, selectively and sensitively reflects variations of certain metal concentrations in ambient waters and thus serves as a reliable biomonitor for these contaminants in a variety of coastal and estuarine areas.

Animals↗
PubMed2003

Considerations about TENORM: a study case on niobium facilities.

Two niobium mining facilities located at two different geological settings were selected as case studies for assessing the radiological impacts associated with mining and milling activities. The impacts were assessed both for operational and post-operational (future unrestricted use of the area) scenarios. The work methodology encompassed sampling and analysis of different materials along the operational process, including wastes, effluents and by-products, mass balance calculations, and dose assessment. The exposure scenario considered during the operational phase included the land use by hypothetical groups of members of the general public. In the case of post-operational phase the possible occupation of contaminated areas was considered. The results pointed out that during the operational phase of the investigated industries no relevant impacts could be attributed to them. However, in the case of the potential occupation of the contaminated areas where the wastes are being deposited, the unrestricted use of these areas cannot be accepted in terms of the relevant radiation protection requirements.

Environmental Exposure↗
PubMed2002

Environmental radiological impact associated with non-uranium mining industries: a proposal for screening criteria.

Niobium, phosphate, coal and gold mining facilities have been selected as case studies with the aim of identifying possible sources of radiological impact during and after cessation of industrial operations. The results have shown that acid drainage, as well as chemical processing of mineral ores, constitute relevant impact indicators for present-day and future scenarios. The possible use of solid wastes abandoned at the end of the operations represents a long-term radiological concern. Therefore, it is necessary that Brazilian legislation for environmental licensing be revised taking into account the potential environmental and radiological impacts caused by these industries and establishing remedial procedures for waste storage areas in the existing sites. The indicators developed and procedures carried out can be used in screening for decisions on the adoption of regulatory requirements for practices at such types of installations.

Brazil↗
PubMed2002

Radon dynamics and reduction in an underground mine in Brazil. Implications for workers' exposure.

This work was aimed at studying the behaviour of 222Rn in an experimental underground copper mine in Brazil with a single entrance. The 222Rn concentrations, meaured by using a dynamic radon measuring technique. varied between 30.5 Bq.m(-3), during ventilated conditions applied to the mine galleries, and 19.4 x 10(3) Bq.(-3) for non-ventilated conditions and when operational mining activities were conducted inside. High radon concentration surges were observed after blasting and drilling activities. In the cases of inadequate ventilation, it was estimated that workers could be subjected to exposures as high as 10 microSv.h(-1), only due to 222Rn and its short-lived progeny. The results show the importance of real-time measurements to evaluate radon dynamics during mining operations.

Air Pollutants, Radioactive↗
PubMed2001

Assessment of acid rock drainage pollutants release in the uranium mining site of Poços de Caldas--Brazil.

We compared three different techniques to assess acid drainage occurrence connected to pyritic waste rock piles at a uranium mining and milling site in Poços de Caldas--Brazil: (1) mass balance calculations, (2) column leaching experiments and (3) geochemical modelling. The study site was chosen because all the drainage coming from the pile is collected in one holding pond and a huge database (monitoring program) was available. The three independent methods predicted similar values for the intrinsic oxidation rate (IOR) (about 10(-9) kg m-3 s-1). We estimate the total time for consumption of all oxidizable material in the dump to be greater than 500 years. Geochemical model results showed a good agreement between predicted sulphate concentrations in relation to those found in the waste pile drainage, although the Al values were overestimated and pH values were underestimated.

Acids↗
PubMed2000

Changes in cerebral blood flow as measured by HMPAO SPECT in patients following spontaneous intracerebral haemorrhage.

Lack of an effective treatment for spontaneous intracerebral haemorrhage (ICH) is partly because the mechanism of neuronal damage in ICH is not fully understood. Animal experiments have shown that there is a zone of ischaemia and oedema around the haematoma which can be reduced by early evacuation of the mass lesion. We set out to study Cerebral Blood Flow (CBF) changes in patients with ICH. We present data on 13 patients (mean age 60). SPECT scans were performed within 48 hours of ictus and 4-7 days later. Four patients had surgical evacuation of the clot; 9 were managed conservatively. The ratio of uptake of the isotope in the cerebral hemisphere containing the haematoma to the isotope uptake in the contra-lateral (un-affected) cerebral hemisphere was taken as an index of perfusion of the affected cerebral hemisphere. The perfusion index of the affected hemisphere improved between the first and the second scans in all the surgically treated patients; in the conservatively managed group, it was worse in 6 patients, the same in 1 and very slightly better in 2. There was an overall mean improvement of 3.87% in the surgical group, and an overall mean deterioration of 3.61% in the medical group. This data suggests that surgical evacuation of the clot may improve perfusion in the ipsilateral cerebral hemisphere in ICH. It underlines the importance of a prospective randomised trial to assess the value of surgery in patients with ICH. The Surgical Trial in Intracerebral Haemorrhage (STICH) is currently underway worldwide. We also describe the application of Difference Based Region Growing (DBRG) to SPECT image analysis. This method overcomes the difficulties posed by 1) the presence of a mass lesion and 2) surgical evacuation of haematoma.

Brain↗
PubMed2000

Continuous monitoring of ICP and CPP following ICH and its relationship to clinical, radiological and surgical parameters.

Sixty-two patients with a spontaneous supratentorial haemorrhage had continuous Intracranial Pressure (ICP) and Cerebral Perfusion Pressure (CPP) monitoring. In addition to the recordings of physiological data their past medical history, presenting neurological state, Computed Tomograph (CT) findings, daily Glasgow Coma Score (GCS) and outcome were noted. The mean age was 57.6 years (sd 13.3). Onset of recording, after ictus was at a mean of 32.6 hours (sd 26.0). Average length of recording was 62.0 hours (sd 39.8). Thirty-one patients had evacuation of haematoma, 6 insertion of External Ventricular Drain (EVD). Preoperative measures of ICP were significantly related to delayed neurological deterioration, death within three days and Glasgow Outcome Scale (GOS) at neurosurgical discharge. No such relationships existed with preoperative measures of CPP and neither ICP nor CPP was related to outcome at 6 months. Post-operative measures of both ICP and CPP demonstrated a significant relationship with death within three days of ictus and GOS at neurosurgical discharge. Again no relationship existed with these parameters and outcome at six months. Surgical evacuation of haematoma acted to significantly reduce ICP and improve CPP. Given that these factors seem to be related to deterioration, death and early outcome, it would seem that surgery could play a role in reducing mortality and improving outcome following Intra cerebral Haemorrhage (ICH).

Blood Pressure↗
PubMed2000

Surgery in intracerebral hemorrhage. The uncertainty continues.

BACKGROUND AND PURPOSE: Primary intracerebral hemorrhage (ICH) accounts for 10% to 20% of stroke but carries the highest rates of mortality and morbidity of all stroke subtypes. Current treatment, however, is varied and haphazard. The most recent Cochrane systematic review refers to 4 prospective, randomized controlled trials. We present a further meta-analysis to include 3 new trials. In addition, we review the trials of Chen et al and McKissock et al and discuss aspects of their quality that, we believe, prevent their inclusion in modern day meta-analysis. METHODS: Literature databases and articles were searched from 1966 to October 1999. Using the end points of death and dependency, the results of the 7 identified randomized trials were expressed as odds ratios. All available data were then analyzed with meta-analysis techniques. Analysis of relevant subsets of trials was also carried out. RESULTS: Meta-analysis of all 7 trials shows a trend toward a higher chance of death and dependency after surgery (OR 1.20; 95% CI 0.83 to 1.74). Meta-analysis was also carried out after exclusion of the Chen and McKissock trials for reasons discussed in the text. This meta-analysis suggests a benefit from surgery, with a reduction in the chances of death and dependency after surgical treatment by a factor of 0.63 (OR 0.63; 95% CI 0.35 to 1.14). CONCLUSIONS: When meta-analysis is restricted to modern-day, post-CT, well-constructed, balanced trials, a trend for surgery to reduce the chances of death and dependency is found. Perhaps, then, in the modern era of CT, good neuroanesthesia, intensive care, and the operating microscope, surgery has a role in the treatment of supratentorial intracerebral hemorrhage. The results of a large, multicenter, randomized controlled trial are urgently needed, and the ongoing International Surgical Trial of Intracerebral Hemorrhage should fulfill this objective.

Cerebral Hemorrhage↗
PubMed1999

Spontaneous intracerebral haemorrhage: a surgical dilemma.

The optimal management, surgical or otherwise, of a patient following a spontaneous intracerebral haemorrhage (ICH) remains controversial. A survey of British neurosurgeons was carried out to assess current attitudes and practice. Patient management was most consistently influenced by the depth (71% agreement), dominance (74.3% agreement) and site (44.7%) of the haematoma. Almost half of neurosurgeons said they would evacuate an ICH in a deteriorating patient, but management choice was very varied in stable patients. However, 80% of the same respondents felt evacuation was helpful in reducing mortality, and 71.3% morbidity. Fifteen per cent of respondents were not influenced by the size of an ICH, but 31% would readily operate on haematomas with volumes of between 50 and 80 ml. Over 30% felt that there was no optimal time for surgical evacuation, but 66.9% felt delayed evacuation was helpful. Premorbid dependency was a stronger influence than age on management choice. Despite these variations, over half felt that they were consistent in their treatment of ICH. However, 81% expressed surgical uncertainty. Furthermore, respondents demonstrated a significant tendency to intervene surgically more readily in ICH related to aneurysm or AVM. Results from a prospective randomized controlled trial to assess the role of surgery are urgently needed.

Cerebral Hemorrhage↗
PubMed1998

Clinical evaluation of the Codman microsensor intracranial pressure monitoring system.

INTRODUCTION: The use of the Camino fibre-optic subdural device for measuring Intracranial Pressure (ICP) in patients, has been shown to correlate well with recordings from the "gold standard" intraventricular fluid filled catheter [1]. Following this work, its use has become standard in the clinical monitoring of patients. More recently, laboratory studies have demonstrated accuracy, acceptable drift and high fidelity for the new Codman Microsensor ICP Transducer, a miniature strain gauge mounted on a flexible nylon catheter [3]. Its performance in patients, however, has yet to be fully assessed, in comparative studies. METHODS: Eight patients (5 head injured, 3 with an Intracerebral haematoma) had a Codman Microsensor inserted. A Camino Transducer was fitted immediately adjacent to it. A computerised system was used to continuously record both ICP readings. RESULTS: In total 140,323 recordings were made over a wide range of ICP values. Study periods ranged from 0.5 to 116 hours. In one patient the Codman transducer tracing failed after several days, probably due to fracture of electrical cable close to the interface box. The readings from the two ICP transducers were compared on Time Series, logistic regression and Altman-Bland plots. Drift of the ICP recorded by the Codman microsensor, was noted in 2 patients, 1 in positive direction (maximum 30 mmHg), 1 negative (max. 20 mmHg). In both cases the Camino ICP recording was relatively stable. In 24% of the recordings the Codman microsensor recorded ICP as 5 or more mmHg greater than the Camino, this difference was 10 mmHg or greater in 9% of recordings. Conversely the Camino recording was 5 mmHg or more, than the Codman, in 5% of all recordings, and 10 mmHg or more in 3%. CONCLUSION: These differences could in the majority of cases (excepting the negative drift) be explained by a constant offset of the Codman transducer, as described previously [6]. Further examination of this device is required.

Brain Injuries↗
PubMed1997

Heavy metal distribution in sediments and ecological risk assessment: The role of diagenetic processes in reducing metal toxicity in bottom sediments.

This paper describes the heavy metal distributions in river and lagoonal sediments of Jacarepaguá Basin, Rio de Janeiro, Brazil. The occurrence of metal phase translocation from the reducible to the oxidizable was observed for Fe, Mn and Ni, from the fluvial environment to the lagoonal. Cu was mainly associated with the oxidizable phase while Zn and Pb were mainly associated with the reducible phase in both environments. It has been demonstrated that metal sulfide formation and complexation by organic complexes are very important aspects in terms of toxicity reduction. By means of a risk assessment methodology, based on available sediment data, it was demonstrated that the lagoonal system is exposed to a low potential ecological risk and that Zn was the metal of greater concern with respect to the system pollution.

Journal Article↗
PubMed1994

Heavy-metal pollution assessment in the coastal lagoons of Jacarepaguá, Rio de Janeiro, Brazil.

The Jacarepaguá lagoon receives the waste from 239 industries and domestic sewage. Bottom sediment analysis revealed that metal pollution is not spread over the lagoons but restricted to the discharge areas of the main metal-carrier rivers. Metal concentrations in superficial water showed the following concentrations values in ng/ml: Zn, 9.63+/-3.59; Pb, 0.61+/-0.43; Cu, 0.94+/-0.45; Mn, 12.7+/-8.0. Metal concentration in fish (average of seven different species) presented the following results, in mg/kg wet weight: Cr, 0.08+/-0.01; Cu, 0.4+/-0.15; Zn, 4.6+/-3.4; Fe, 2.4+/-1.3; Mn, 0.4+/-0.3. These results imply, considering fish consumption rate and the RfD (USEPA Reference Dose), that the local population is not exposed to undue health risks. Metal concentrations in the water may, however, increase due to their dissolution induced by pH and redox changes in the sediments.

Journal Article↗
PubMed1994

Anterior cervical discectomy: an improvement in donor site operative technique.

Bone graft harvest from the iliac crest for anterior cervical discectomy is common surgical practice. Its rate of complication remains far higher than that of the cervical operation. We describe a method of harvest that we believe reduces post-operative complications and pain, facilitating early patient mobilization and discharge.

Bone Transplantation↗