Timing and climate forcing of volcanic eruptions for the past 2,500 years.

Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.

A Method for Continuous (239)Pu Determinations in Arctic and Antarctic Ice Cores.

Atmospheric nuclear weapons testing (NWT) resulted in the injection of plutonium (Pu) into the atmosphere and subsequent global deposition. We present a new method for continuous semiquantitative measurement of (239)Pu in ice cores, which was used to develop annual records of fallout from NWT in ten ice cores from Greenland and Antarctica. The (239)Pu was measured directly using an inductively coupled plasma-sector field mass spectrometer, thereby reducing analysis time and increasing depth-resolution with respect to previous methods. To validate this method, we compared our one year averaged results to published (239)Pu records and other records of NWT. The (239)Pu profiles from the Arctic ice cores reflected global trends in NWT and were in agreement with discrete Pu profiles from lower latitude ice cores. The (239)Pu measurements in the Antarctic ice cores tracked low latitude NWT, consistent with previously published discrete records from Antarctica. Advantages of the continuous (239)Pu measurement method are (1) reduced sample preparation and analysis time; (2) no requirement for additional ice samples for NWT fallout determinations; (3) measurements are exactly coregistered with all other chemical, elemental, isotopic, and gas measurements from the continuous analytical system; and (4) the long half-life means the (239)Pu record is stable through time.

Long-term outcome after surgical treatment of Scheuermann's Kyphosis (SK).

STUDY DESIGN: A retrospective observational cohort study with a minimum follow-up of 10 years of patients who underwent surgery for Scheurmann Kyphosis (SK). OBJECTIVE: Evaluate the long-term clinical and radiological outcome of patients with SK who either underwent combined anterior-posterior surgery or posterior instrumented fusion alone. There is paucity of literature for long-term outcome studies on SK. The current trend is towards only posterior (PSF) surgical correction for SK. The combined strategy of anterior release, fusion and posterior spinal fusion (AF/PSF) for kyphosis correction has become historic relic. Long-term outcome studies comparing the two procedures are lacking in literature. METHODS: 51 patients (30 M: 21F) who underwent surgery for SK at a single centre were reviewed. Nineteen had posterior instrumentation alone (PSF) (Group 1) and 32 underwent combined anterior release, fusion with posterior instrumentation (AF/PSF) (Group 2). The clinical data included age at surgery, gender, flexibility of spine, instrumented spinal levels, use of cages and morcellised rib grafts (in cases where anterior release was done), posterior osteotomies and instrumentation, complications and indications for revision surgery. Preoperative flexibility was determined by hyperextension radiographs. The radiological indices were evaluated in the pre-operative, 2-year post-operative and final follow-up [Thoracic Kyphosis (TK), Lumbar lordosis (LL), Voustinas index (VI), Sacral inclination (SI) and Sagittal vertical axis (SVA)]. The loss of correction and incidence of JK (Junctional Kyphosis) and its relation to fusion levels were assessed. Complications and difference in outcome between the two groups were analyzed. RESULTS: The mean age at surgery for 51 patients was 20.6 years who were followed up for a minimum of 10 years (mean: 14 years; range 10-16 years). The mean age was 18.5 ± 2.2 years and 21.9 ± 4.8 years in groups 1 and 2, respectively. The mean pre- and 2-year post-operative ODIs were 32.6 ± 12.8 and 8.4 ± 5.4, respectively, in group 1 (p < 0.0001) and 30.7 ± 11.7 and 6.4 ± 5.7, respectively, in group 2 (p < 0.0001). The final SRS-22 scores in group 1 and 2 were 4.1 ± 0.4 and 4.0 ± 0.35, respectively (p = 0.88). The preoperative flexibility index was 49.2 ± 4.2 and 43 ± 5.6 in groups 1 and 2, respectively (p < 0.0001). The mean TKs were 81.4° ± 3.8° and 86.1° ± 6.0° for groups 1 and 2, respectively, which corrected to 45.1° ± 2.6° and 47.3° ± 4.8°, respectively, at final follow-up (p < 0.0001). The mean pre-operative LL angle was 60.0° ± 5.0° and 62.4° ± 7.6° in groups 1 and 2, respectively, which at final follow-up was 45.1° ± 4.4° and 48.1° ± 4.8°, respectively (p < 0.0001). The mean pre-operative and final follow-up Voustinas index (VI) in group 1 were 22.9 ± 2.9 and 11.2 ± 1.2, respectively, and in group 2 was 25.9 ± 3.5 and 14.0 ± 2.3, respectively. The mean pre-operative and final follow-up SI angle were 43.6° ± 3.3° and 31.2° ± 2.5° in group 1, respectively, and 44.3° ± 3.5° and 32.1° ± 3.5° in group 2, respectively (p < 0.0001). The pre-operative and final follow-up SVA in group 1 were - 3.3 ± 1.0 cms and - 1.3 ± 0.5 cms, respectively, and in group 2 was - 4.0 ± 1.3cms and - 1.9 ± 1.1cms, respectively (p < 0.0001). Though the magnitude of curve correction in the groups 1 and 2 was significant 36° vs 39° (p = 0.05), there was no significant difference in correction between the two groups. Proximal JK was seen in seven and distal JK in five patients were observed in the whole cohort. CONCLUSION: The long-term clinical outcomes for both PSF and AF/PSF are comparable with reproducible results. No difference was noted in loss of correction and outcome scores between the two groups. The correction of thoracic kyphosis (TK) had a good correlation with ODI. AF/PSF had much higher complications than PSF group. The objective of correcting the sagittal profile and balancing the whole spinal segment on the pelvis can be achieved through single posterior approach with fewer complications.

TOWARD NATIONAL CT DIAGNOSTIC REFERENCE LEVELS IN THE UNITED ARAB EMIRATES: A MULTICENTER REVIEW OF CT DOSE INDEX AND DOSE LENGTH PRODUCT.

This multicenter study evaluated computed tomography dose index volume (CTDIvol) and dose length product (DLP) to contribute to establishing computed tomography (CT) national diagnostic reference levels (NDRLs) in the United Arab Emirates (UAE). Data from 240 patients, who underwent CT head, chest, abdomen-pelvis and urography examinations, were analyzed, including patient age, sex and weight, CTDIvol (mGy) and DLP (mGy cm). The proposed DRLs for each examination were calculated as the third quartile. DRLs are proposed using CTDIvol (mGy) and DLP (mGy cm) for CT head (67 and 1189, respectively), chest (8 and 302, respectively), abdomen-pelvis (28 and 1122, respectively) and urography (20 and 714, respectively). These values are comparable with the initial NDRLs and published international DRLs. Baseline values for International Radiology Center (IRC) CT DRLs were calculated on frequently performed CT examinations. Implementation of DRL values improves dose optimization based on procedures, scanner type and patient characteristics while maintaining acceptable image quality and diagnostic confidence.

Could musculo-skeletal radiograph interpretation by radiographers be a source of support to Australian medical interns: A quantitative evaluation.

INTRODUCTION: Public expectations regarding access to the emergency department (ED) challenges providers and policy makers with finite resources being stretched beyond capacity. To enable education of a greater numbers of doctors the format of the medical internship in Australia has changed and assumes that sufficient supervision is provided to interns to enable image interpretation skills development. Furthermore this assumes that appropriate foundational skills are established during undergraduate education. METHODS: A mixed methods approach using a convenience, self selecting sample population of radiographers and final year medical students was adopted. The study measured the interpretive ability of final year medical students and radiographers in musculo-skeletal trauma (MSK) plain radiographic images. An image test bank based upon radiologist consensual agreement was corrected for prevalence and bias. Performance across a range of measurements was completed and compared for statistical significance using Mann-Whitney U. RESULTS: Results were divided to enable analysis across age ranges and types of skeletal presentation. Radiographer performance was better numerically and demonstrated statistically significant difference in several areas. CONCLUSION: Radiographers have the knowledge base to assist junior doctors to clinically interpret the musculo-skeletal radiographic image. To meet the requirements of AMC and the Medical Board of Australia (MBA), a tailored clinically based educational system could be developed and provided by an accredited radiographer. Australian radiographers could also be employed to provide a safety net to avoid misinterpretation, such as seen in the UK commenting system, operating as an interprofessional team.

Effect of digitalis on human ventricular refactoriness.

In order to evaluate the effect of digitalis on the effective refractory period of the human ventricle, 14 patients were studied with atrial or ventricular pacing and with the introduction of ventricular extra-stimuli. The ventricular effective refractory period (VERP) was recorded before and after 1.0 to 1.25 mg ouabain given intravenously and the results compared with similar changes in the Q-T interval. During atrial pacing (eight patients) at rates of 70 to 110 beats per minute, ouabain reduced the mean ventricular effective refractory period from 290 +/- 13 ms to 260 +/- 16 ms (P less than 0.01) and the mean Q-T interval was reduced from 372 +/- 18 ms to 359 +/- 19 ms (P less than 0.01); the mean VERP/Q-T ratio was 0.79 +/- 0.04 before ouabain and 0.73 +/- 0.04 after ouabain (P less than 0.01). Utilising ventricular drive pacing (six patients) the mean ventricular effective refractory period was reduced from 245 +/- 16 ms to 226 +/- 13 ms (P less than 0.01) and the mean Q-T interval reduced from 382 +/- 18 ms to 360 +/- 29 ms (P less than 0.01). There was no significant change in the mean VERP/Q-T ratio (0.63 +/- 0.04 before vs 0.63 +/- 0.04 after ouabain). The results demonstrate that clinically effective doses of ouabain produce a significant reduction of the effective refractory period of the human ventricle. This change is accompanied by a reduction in the VERP/Q-T ratio during atrial pacing.

Recurrent bacterial meningitis: coronal thin-section cranial computed tomography to delineate anatomic defects.

Three patients with histories of recurrent bacterial meningitis were previously examined with skull and sinus radiographs, routine cranial computed tomography, intrathecal radioisotope tracer studies, and immunologic evaluation. None of these studies were diagnostic. Pneumococcal vaccine and prophylactic penicillin therapy were ineffective in preventing recurrent episodes in two cases. Thin-section (2-mm) direct coronal computed cranial tomography demonstrated anatomic defects in all three patients. The use of metrizamide cisternography was not necessary to diagnose the defects. All patients had basiethmoidal encephaloceles which were repaired surgically. Direct coronal computed tomography offers a relatively easy noninvasive method for delineating anatomic abnormalities in patients with recurrent meningitis.

Prospective utility of cerebral proton magnetic resonance spectroscopy in monitoring HIV infection and its associated neurological impairment.

Neurological manifestations of HIV disease occur in most adults and children with AIDS. Many of those affected will inevitably suffer clinical neurological deficits involving mental function, movement, and sensation. Surprisingly, there are not as yet adequate monitoring systems to predict the onset and/or progression of HIV infection of the CNS. Neurological, neuropsychological, CSF, and magnetic resonance imaging (MRI) analyses cannot accurately detect mental deterioration during advancing HIV disease. Reports suggest that in vivo proton MR spectroscopy (1H MRS) of the brain could be a predictor of virus-induced neurological deterioration. H MRS can measure N-acetylaspartate (NAA), a metabolite present only in neurons. Decreased NAA reflects neuronal loss seen during HIV infection of brain. To uncover possible associations between NAA levels and HIV-induced neurological disease we performed serial 1H MRS brain tests in HIV-infected patients with or at risk for encephalopathy. Serial testing, for 1 year, of 10 patients showed that brain NAA levels decreased in all HIV-infected subjects. The most severe NAA reductions were associated with progressive neurological impairment. These findings suggest that NAA can be used as a noninvasive measure of neuronal loss in patients with HIV disease. Most important, the results suggest that 1H MRS could be used to monitor therapeutics directed against HIV infection within the CNS.

Cerebral infarction associated with protein C deficiency following allogeneic bone marrow transplantation.

Hypercoagulable states associated with deficiencies in circulating anticoagulant protein C occur after chemotherapy for a variety of malignant diseases. Protein C deficiency also occurs following bone marrow transplantation (BMT) and may be responsible for a variety of transplantation-associated complications. We report the case of a child who suffered a stroke associated with low protein C antigen and activity occurring 11 months after allogeneic BMT. Protein C levels recovered spontaneously by 18 months after BMT. We speculate that the protein C deficiency and and resultant hypercoagulable state led to the stroke, and the deficiency of this anticoagulant was a sequela of the transplant.

Neutrophils from systemic lupus erythematosus patients demonstrate increased nuclear DNA damage.

OBJECTIVE: (i) To determine the levels of nuclear DNA damage in freshly isolated and cultured neutrophils from SLE patients (SLE), rheumatoid arthritis patients (RA) and healthy individuals and relate these to the percentage of apoptotic neutrophils. (ii) To assess rates of repair of neutrophil oxidative DNA damage. METHODS: The comet assay was used to quantify nuclear DNA damage in neutrophils from SLE patients (n = 20), control subjects (n = 15) and RA patients (n = 15). Levels of DNA damage were related to apoptosis as assessed by annexin V binding and morphology. Rates of repair of neutrophil oxidative DNA damage was measured by incorporating formamidopyrimidine-DNA glycosylase (FPG) into the comet assay. RESULTS: Nuclear DNA damage in freshly isolated and cultured (20 h) neutrophils was significantly greater in SLE patients (median = 12.5%, 27.3%; respectively) compared with RA patients (median = 9.4%, p = 0.002; 19.3%, p = 0.002; respectively) and control subjects (median = 8.2%, p = 0.003; 18.7%, p = 0.01, respectively). Significantly higher levels of circulating apoptotic neutrophils were demonstrated in SLE patients compared to RA and control subjects. Similar findings were observed following 20 h cultured neutrophil preparations. However, no significant direct correlation between neutrophil apoptosis and DNA damage was observed. Neutrophils from 3 of 5 SLE patients demonstrated an impaired ability to repair oxidatively modified DNA. CONCLUSION: Neutrophils from SLE patients display increased DNA damage and, additionally, may demonstrate defective repair of oxidative DNA damage. These features, in addition to increased rates of neutrophil apoptosis, may act as contributing factors to autoantigen excess and immune activation.

Behavioral and physiological sex differences observed in an animal model of fulminant hepatic encephalopathy in the rat.

Hepatic encephalopathy is characterized by a number of neuropsychiatric and motor disturbances observed in patients with liver dysfunction. The purpose of this study is to fully characterize behavioral and physiological sex differences in an animal model of fulminant hepatic encephalopathy (FHE). Male and female rats were administered thioacetamide (600 mg/kg) via i.p. (intraperitoneal) injection at Hours 0 and 24 and allowed to progress into the four stages of FHE. Male rats reached all four stages of FHE significantly earlier than female rats (p < 0.05). The performance of the male rats deteriorated more quickly (p < 0.05) than that of the females in all of the sensory and motor behavioral tests. Sex differences were observed in the liver enzymes of the FHE rats. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase were significantly greater (p < 0.05) in male rats in all four stages of FHE. Significant increases were also observed in the levels of direct and total bilirubin (p < 0.05). Neuronal damage was observed in the CA1 and CA2 regions of the hippocampus. In the CA1 region, male rats displayed greater pathological changes in Stages III and IV (p < 0.05) than female rats. The damage in the CA2 region was only observed in Stage IV male rats. Our data indicate that observable behavioral and physiological sex differences occur in thioacetamide-induced FHE in the rat.

Central nervous system aspergillosis. Analysis of 26 patients.

The clinical presentation, risk factors, laboratory data, and neuroimaging and neuropathological findings in 26 patients with autopsy proved central nervous system (CNS) aspergillosis are reviewed. Eleven patients had hematological malignancies (8 underwent bone marrow transplantation), 8 patients underwent liver transplantation, and 3 patients had acquired immunodeficiency syndrome. Four had illnesses resulting in immunosuppression (systemic lupus erythematosus, infected aortic graft, neuroblastoma, and fulminant hepatic failure). The most common presenting clinical symptoms of CNS aspergillosis were fever and a strokelike syndrome. Risk factors for developing CNS aspergillosis included neutropenia, immunosuppressive therapy, low CD4 counts, and retransplantation. Spinal fluid findings were nondiagnostic. Computed tomograms and magnetic resonance scans of the head showed low-density lesions or hemorrhagic infarctions. Most aspergillosis cases occurred in the setting of widely disseminated disease commonly arising from the lung. Pathologically, multiple areas of necrosis throughout the brain were seen. Aspergillus invasion of blood vessel walls was seen microscopically. Amphotericin B with or without flucytosine was not effective treatment.

Improving radiographer highlighting of trauma films in the accident and emergency department with a short course of study--an evaluation.

The case for radiographer abnormality highlighting in the Accident and Emergency (A&E) department is well documented. Following evaluative feedback, 280 questionnaires were sent nationally to A&E radiology departments (excluding Northern Ireland). The intent of the survey was to ascertain the viability of constructing a short course in trauma plain film pattern recognition in the axial and appendicular skeleton. Following a highly positive response a course was designed and operated on a workshop basis, being lead primarily by reporting radiographers. The course was evaluated for effectiveness using three identical assessments of 42 films, including 12 positive for trauma. A sample of 22 radiographers who attended the pilot course and subsequent courses throughout 1998/99 undertook the assessment. The assessments themselves were performed at the start and end of the course and 6-10 weeks after completion. Results appear to indicate that a significant improvement in the specificity (p = 0.002) and accuracy (p = 0.005) was achieved following the course. In the light of continuing professional development, the course appears to address the needs of the majority of clinical radiographers working in A&E.

Progressive scoliosis in Dubowitz syndrome.

STUDY DESIGN: This case report describes a 17-year-old male with Dubowitz syndrome in whom a progressive left thoracic scoliosis developed that required surgical correction. OBJECTIVE: Scoliosis associated with Dubowitz syndrome had not been previously described among the orthopedic manifestations of this rare syndrome. A review of the literature and the surgical treatment of this patient is presented. SUMMARY OF BACKGROUND DATA: Dubowitz syndrome is a rare autosomal recessive disorder characterized by microcephaly, craniofacial abnormalities, eczematous skin rash, delayed skeletal maturation, and shortness of stature. The orthopedic manifestations of this condition primarily involve the hands and feet with brachyclinodactyly of the fifth finger and syndactyly of the second and third toes. Spinal deformity in these individuals is not well described in the literature. METHODS: Over a 2-year period, the patient's scoliosis progressed to 88 degrees, resulting in severe truncal imbalance without neurologic sequelae. A posterior spinal fusion with segment instrumentation alone was used to correct the deformity. RESULTS: After surgery, excellent restoration of spine sagittal and coronal plane alignment was achieved, resulting in improved sitting and standing balance. CONCLUSION: Patients with Dubowitz syndrome may be at risk of having a progressive, rigid scoliosis. These individuals may need to be observed over a prolonged period for the development of spinal deformity because of the potential for extended delay in skeletal maturation.

Magnetic resonance angiography in the diagnosis of traumatic vertebrobasilar complications: a report of two cases.

Although conventional arteriography is usually performed to study the vertebrobasilar system, we report two cases of traumatic vertebrobasilar vascular occlusion that were diagnosed by magnetic resonance angiography. This enabled us to promptly treat the patients. Our experience suggests that magnetic resonance angiography may be a useful diagnostic tool in the setting of acute vertebrobasilar complications, associated with cervical spine trauma.

Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today.

Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20(th) century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19(th) century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21(st) century.