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Biomedical subjects

J A Ryan

Publications and source records attributed to J A Ryan.

At least 19 recordsLinked to original sources
PubMed2006

micro-XANES and micro-XRF investigations of metal binding mechanisms in biosolids.

Micro-X-ray fluorescence (micro-XRF) microprobe analysis and micro-X-ray absorption near-edge structure (micro-XANES) spectroscopy were employed to identify Fe and Mn phases and their association with selected metals in two biosolids (limed composted [LC] and Nu-Earth) before and after treatment to remove organic carbon (OC). Spatial correlations derived from elemental mapping of XRF images showed strong correlations between Fe and Cd, Cr, Pb, or Zn (r2= 0.65-0.92) before and after removal of most of the OC. The strong correlation between Fe and Cu that was present in intact samples disappeared after OC removal, suggesting that Cu was associated with OC coatings that may have been present on Fe compounds. Except for Fe and Cr, the spatial correlations of metals with Mn were improved after treatment to remove OC, indicating that the treatment may have altered more than the OC in the system. The Fe micro-XANES spectra of the intact biosolids sample showed that every point had varying mixtures of Fe(II and III) species and no two points were identical. The lack of uniformity in Fe species in the biosolids sample illustrates the complexity of the materials and the difficulty of studying biosolids using conventional analytical tools or chemical extraction techniques. Still, these microscopic observations provide independent information supporting the previous laboratory and field hypothesis that Fe compounds play a major role in retention of environmentally important trace elements in biosolids. This could be due to co-precipitation of the metals with Fe, adsorption of metals by Fe compounds, or a combination of both mechanisms.

Fluorescence↗
PubMed2005

Methods for speciation of metals in soils: a review.

The inability to determine metal species in soils hampers efforts to understand the mobility, bioavailability, and fate of contaminant metals in environmental systems, to assess health risks posed by them, and to develop methods to remediate metal contaminated sites. Fortunately, great strides have been made in the development of methods of species characterization and in their application to the analysis of particulates and mixtures of solid phases in physics, analytical chemistry, and materials science. This manuscript highlights a selection of the analytical methods available today offering the greatest promise, briefly describes the fundamental processes involved, examines their limitations, points to how they have been used in the environmental and geochemical literature, and offers some suggested research directions in the hope of stimulating further investigation into the application of these powerful tools to the problems outlined above.

Chemistry Techniques, Analytical↗
PubMed2004

Use of fish liver PLHC-1 cells and zebrafish embryos in cytotoxicity assays.

Heat shock proteins (HSPs) indicate exposure to cellular stress and adverse cellular effects, thus serving as biomarkers of these effects. The highly conserved Hsp70 proteins are expressed under proteotoxic conditions, whereas small HSPs are expressed in response to stressors acting on the cytoskeleton and cell signaling pathways. Poeciliopsis lucida hepatocellular carcinoma line 1 (PLHC-1) cells have been used extensively for studying effects of cytotoxicity. A number of assays have been developed to examine DNA levels, protein levels, growth rate, morphological changes, and viability. The boundary between sub-lethal and lethal effects of particular stressors has been determined. The methodology and analytical framework for these techniques along with sample assays using cadmium stressed PLHC-1 cells are described. A range of methodologies have been developed in the past decade that allow the analysis and interpretation of gene expression and function in vivo in zebrafish embryos, and many of these are now being applied to the development of embryotoxicity assays. Here we provide the theoretical background and methodology for utilizing Hsp70 expression as an indicator of toxicity in the zebrafish embryo. Hsp70 expression is activated in a tissue-specific manner in zebrafish larvae following exposure to a number of different toxicants, including cadmium. This has allowed the development of an hsp70/eGFP reporter gene system in stable transgenic zebrafish that serves as a reliable yet extremely quick indicator of cell-specific toxicity in the context of the multicellular, living embryo.

Animals↗
PubMed2003

Psychopathology in people with epilepsy and intellectual disability; an investigation of potential explanatory variables.

OBJECTIVES: There are few studies on epilepsy and psychopathology in people with intellectual disability (mental retardation) despite epilepsy prevalence rates that are thirty times higher than in the general population. The aims of this study, therefore, were to identify reliable, epilepsy-specific predictors of psychiatric and behavioural disorder in these patients, and to investigate reliable predictors of carer stress. METHODS: A database of 685 patients was compiled, from which 250 were randomly selected. Structured interviews were completed on 186 of these 250 patients (74%) (108 men, 78 women; mean age (SD) 35.5 (10.1)) comprising descriptive, clinical and functional components, and validated measures of psychopathology for which comparative data were available. Logistic and linear regression methods were used to identify predictors. RESULTS: One-third of patients with epilepsy and intellectual disability met criteria for possible psychiatric disorder, particularly affective/neurotic disorder; twice the comparison rates for intellectual disability alone. Behavioural problem levels, however, were lower than population norms. Regression models explaining modest amounts of variance (R(2)< or =24%) suggested certain seizure phenomena (greater seizure severity, more seizures in past month, lesser tendency to loss of consciousness during seizures) as particular risk factors for psychiatric disorder. General disability factors such as level of intellectual, sensory or motor disability and side effects of medication, however, contributed more to explaining behavioural problems. Around half of the family carers reported significant stress, and one-third exhibited clinically significant anxiety symptoms. Younger carers were more stressed, and side effects from patients' medication also contributed to carer stress. CONCLUSIONS: Although epilepsy in itself may be a risk factor for psychopathology in a minority of people with intellectual disability, some epilepsy-specific factors may predict psychiatric disorder. Behavioural problems need to be considered separately from psychiatric disorder because general factors, more closely associated with disability, are stronger predictors of their occurrence.

Adolescent↗
PubMed2001

Formation of chloropyromorphite in a lead-contaminated soil amended with hydroxyapatite.

Conversion of soil Pb to pyromorphite [Pb5(PO4)3Cl] was evaluated by reacting a Pb contaminated soil collected adjacent to a historical smelter with hydroxyapatite [Ca5(PO4)3OH]. In a dialysis experiment where the soil and hydroxyapatite solids were placed in separate dialysis bags suspended in 0.01 M NaNO3 solution a crystalline precipitate, identified as chloropyromorphite, formed on the dialysis membrane containing the soil. The aqueous composition of the solution indicated that dissolution of solid-phase soil Pb was the rate-limiting step for pyromorphite formation. Addition of hydroxyapatite to the soil caused a decrease in each of the first four fractions of sequential extractable Pb and a 35% increase in the recalcitrant extraction residue. After a 240-d incubation at field-moisture content there was a further increase in the recalcitrant extraction residue fraction of the hydroxyapatite-amended soil to 45% of the total soil Pb. The increase in the extraction residue fraction in the hydroxyapatite amended 0-d incubated soil as compared to the control soil illustrates that the chemical extraction procedure itself caused changes in extractability. Thus, the chemical extraction procedure cannot easily be utilized to confirm changes occurring in amended soils. The further increase after the 240-d incubation implies that the reaction also occurs in the soil during incubation. Extended X-ray absorption fine structure (EXAFS) spectroscopy indicated that after the 240-d incubation the hydroxyapatite treatment caused a change in the average, local molecular bonding environment of soil Pb. Low-temperature EXAFS spectra (chi data and radial structure functions--RSFs) showed a high degree of similarity between the chemical extraction residue and synthetic pyromorphite, providing additional evidence that the change of soil Pb to pyromorphite is possible by simple amendments of hydroxyapatite to soil.

Absorptiometry, Photon↗
PubMed2001

Effects of pH on dechlorination of trichloroethylene by zero-valent iron.

The surface normalized reaction rate constants (k(sa)) of trichloroethylene (TCE) and zero-valent iron (ZVI) were quantified in batch reactors at pH values between 1.7 and 10. The k(sa) of TCE linearly decreased from 0.044 to 0.009l/hm(2) between pH 3.8 and 8.0, whereas the k(sa) at pH 1.7 was more than an order higher than that at pH 3.8. The degradation of TCE was not observed at pH values of 9 and 10. The k(sa) of iron corrosion linearly decreased from 0.092 to 0.018l/hm(2) between pH 4.9 and 9.8, whereas it is significantly higher at pH 1.7 and 3.8. The k(sa) of TCE was 30-300 times higher than those reported in literature. The difference can be attributed to the pH effects and precipitation of iron hydroxide. The k(sa) of TCE degradation and iron corrosion at a head space of 6 and 10ml were about twice of those at zero head space. The effect was attributed to the formation of hydrogen bubbles on ZVI, which hindered the transport the TCE between the solution and reaction sites on ZVI. The optimal TCE degradation rate was achieved at a pH of 4.9. This suggests that lowering solution pH might not expedite the degradation rate of TCE by ZVI as it also caused faster disappearance of ZVI, and hence decreased the ZVI surface concentration.

Chlorine Compounds↗
PubMed2001

Management and long-term follow-up of hepatic cysts.

PURPOSE: To provide an algorithm for the management of hepatic cysts through an analysis of our series over 16 years. METHOD: We reviewed the surgical management and outcome of patients with hepatic cysts between 1984 and 2000 at a single institution. Data were collected by chart review, telephone interview, and follow-up hepatic ultrasonography. RESULTS: Forty-four patients (36 females, 8 males) underwent a total of 46 operations for hepatic cysts (mean size 12.0 +/- 5.2 cm) with a mean follow-up of 5.1 +/- 4.0 years. We treated 28 simple cysts, 4 polycystic liver disease (PCLD), 7 cystadenomas, 2 hydatid cysts, 1 cystadenocarcinoma, 1 endometrioma, and 1 hepatic foregut cyst. Operations included simple drainage, wide unroofing (open and laparoscopic), and hepatic resection. Four patients experienced a symptomatic recurrence after definitive treatment; 3 of these patients had PCLD. Four of the 7 patients with cystadenomas had undergone previous operations that required subsequent definitive resection without a recurrence. CONCLUSIONS: The preoperative distinction between simple cysts and cystadenomas/cystadenocarcinomas can be difficult, yet the management is different. Unroofing is a safe and effective operation for patients with simple cysts. Patients with PCLD frequently have recurrences. Cystadenomas should be completely resected owing to the likelihood of recurrence after partial excision and the risk of eventual cystadenocarcinoma. We present a treatment algorithm for the preoperative evaluation and management of hepatic cysts based on the largest number of patients with the longest follow-up reported to date.

Adolescent↗
PubMed2001

The social predictors of adolescent alcohol misuse: a test of the social development model.

OBJECTIVE: This study was conducted to investigate the ability of the social development model (SDM) to predict alcohol misuse at age 16 and to investigate the ability of the SDM to mediate the effects of alcohol use at age 14 on alcohol misuse at age 16. METHOD: The sample of 807 (411 males) is from the longitudinal panel of the Seattle Social Development Project which, in 1985, surveyed all consenting fifth-grade students from 18 elementary schools serving high-crime neighborhoods in Seattle, Washington. Alcohol use was measured at age 14, predictors of alcohol misuse were measured at age 15 and alcohol misuse was measured at age 16. Structural equation modeling was used to examine the fit of the model to the data. RESULTS: All factor loadings were highly significant and the measurement model achieved a good fit with the data (Comparative Fit Index [CFI] = 0.93). A second-order structural model fit the data well (CFI = 0.91) and also explained 45% of the variance in alcohol misuse at age 16. The SDM partially and significantly mediated the direct effect of age-14 alcohol use on age-16 alcohol misuse. CONCLUSIONS: The risk and protective processes specified by the SDM serve as potential targets for the prevention or reduction of adolescent alcohol misuse.

Adolescent↗
PubMed1999

Benefits and safety of hepatic resection for colorectal metastases.

BACKGROUND: Metastatic colorectal carcinoma to the liver is a potentially curable disease. The purpose of this study was to determine the safety and efficacy of hepatic resection for metastatic colorectal carcinoma. METHODS: One hundred twenty-one consecutive hepatic resections in 110 patients with metastatic colorectal cancer between January 1978 and September 1998 performed by a single surgeon were reviewed. RESULTS: The actuarial 5-year survival for all patients in the series was 46%. Of the patients operated on before 1993, the actual 5-year survival was 43% and actual disease-free 5-year survival was 28%. The actual 10-year survival was 27%, and of all patients operated on in the last 20 years, 48% are alive today. When comparing initial regional lymph node status, the 5-year survival was 54% for the patients with negative lymph nodes and 40% for patients with positive nodes. Only 18% of patients required a perioperative blood transfusion, and the median length of stay was 7 days. There were complications in 34% of cases, and the operative mortality was 4%. CONCLUSIONS: Hepatic resection for metastatic colon cancer is safe, and significant longevity and cure can be obtained after resection.

Adult↗
PubMed1999

Severe neutropenia as an adverse effect of methimazole in the treatment of hyperthyroidism.

Ms. K., a white, 47-year-old female with a history of hyperthyroidism had been treated with methimazole daily for a period of 9 years. She presented with a 2-day history of fever higher than 103 degrees F and cellulitis of the right arm after a scratch injury. White blood cell count (WBC) was noted at 0.4 x 10(3)/microL and neutrophils at 5.6%, indicating agranulocytosis. Methimazole was discontinued by the patient with the onset of symptoms. Appropriate intravenous antibiotic therapy and reverse isolation were provided in the acute-care setting, as well as administration of the granulocyte colony-stimulating factor (G-CSF) filgrastim. No recovery of the granulocyte count or improvement of clinical condition was noted until her sixth day of admission, at which time her WBC increased to 2.6 x 10(3)/microL. The administration of intravenous antifungals and antibiotics prevented overwhelming sepsis, while giving the G-CSF the opportunity to stimulate growth of granulocytes to finally fight the offending organisms and save this patient.

Antithyroid Agents↗
PubMed1998

Intraductal neoplasms of the pancreas.

BACKGROUND: Since 1980 a group of pancreatic tumors have been termed intraductal papillary mucinous tumors (IPMT). Because these tumors occupy an intraductal position they are demonstrated by pancreatography to reside in the main pancreatic duct (MPD) or side branch ducts (SBD). Lesions of IPMT result in abdominal pain or pancreatitis symptoms because mucin production or papillary growth results in ductal obstruction. Only 104 cases had been reported in the literature by 1996 but more are being presented in abstract form. We reviewed our own 33 cases to assist defining operative decision-making criteria. METHODS: All cases of IPMT between 1989 and 1997 were reviewed for clinical presentation, anatomy by endoscopic retrograde cholangiopancreatography and computed tomography, histologic findings, and long-term outcomes. RESULTS: Our cases were older (65 years) and presented with disease centered mainly in the head of the gland. Clinical presentation was epigastric pain (82%), pancreatitis (56%), weight loss (36%), diabetes (27%), and jaundice (9%). Operations were pancreatectomy in 31 (Whipple n = 15, total n = 5, distal n = 10, local n = 1), bypass only (n = 1), and no operation (n = 1). Malignancy was found in 14 of 33 (42%). Factors significantly associated (P <0.05 Fisher exact test) with malignancy were history of alcohol abuse or death from disease. Jaundice or presence in both MPD and SBD approached a significant association with malignancy but not abdominal pain, weight loss, diabetes, preoperative serum elevations of amylase, SGOT, CA-19-9, or CEA; diffuse MPD dilation, gland region, gross mucus in ducts or filling defects, cytology, calcifications, or a pancreatic mass. In 31 resected patients after a follow-up of 37 months (1 to 103) death had occurred in 6 of 13 malignant cases and 0 of 18 with benign disease. Three-year actuarial survival was 82% (all) and 56% (malignant). Symptom recurrence after resection was found in 6 of 31 at a mean of 13 months postoperatively and was associated with death from disease (P <0.05) or presence of pain preoperatively. CONCLUSION: Malignancy is common with IPMT and is more likely to be present with the clinical history of alcohol abuse or jaundice and if the tumor involves both the MPD and the SBD. The prognosis after resection is better than pancreatic cancer but the 19% recurrence of symptoms was equally seen with benign or malignant cases owing to residual disease in pancreatic remnants. The amount of resection should be extensive in patients likely to have malignancy (alcohol, jaundice, MPD+SBD). In those likely to redevelop symptoms, ie, those with preoperative pain, a careful assessment should be made via imaging studies for extent of disease.

Adult↗
PubMed1998

Serogroup B, electrophoretic type 15 Neisseria meningitidis in Canada.

Invasive meningococcal disease is nationally reportable in Canada. In recent years, a serogroup C genotype, designated electrophoretic type 15 (ET15), has been the most frequently isolated meningococcal genotype in Canada and has caused epidemics across the country. Between August 1993 and September 1995, there were 9 cases of invasive meningococcal disease caused by a variant of this genotype, expressing group B capsular polysaccharide. The appearance of serogroup B:ET15 was related temporally and geographically to mass immunization campaigns designed to control serogroup C meningococcal disease in Canada. Since there is no vaccine available to control serogroup B meningococcal disease, the appearance of this variant may have public-health significance if it demonstrates the same epidemic potential as its serogroup C counterpart.

Adult↗
PubMed1997

Efficacy of selective unilateral exploration in hyperparathyroidism based on localization tests.

OBJECTIVES: To determine the success of unilateral exploration vs bilateral exploration for primary hyperparathyroidism and to analyze the validity of preoperative localization tests. DESIGN: Case-control study of patients who underwent surgical exploration (unilateral, n = 43; bilateral, n = 57) by 1 surgeon from January 1991 through May 1996 and who had ultrasound examination of the neck and thallium-technetium scintigraphy performed before parathyroid surgery. Initially, unilateral exploration was used sparingly, but it became the standard approach in 1994 if localization was correct. SETTING: Urban multispecialty clinic, teaching hospital. PATIENTS: One hundred consecutive patients who underwent surgical exploration for primary hyperparathyroidism. INTERVENTIONS: Ultrasonography of the neck, thallium-technetium scintigraphy, and parathyroidectomy. MAIN OUTCOME MEASURES: Imaging success, operative success, and operative time. RESULTS: In 94 patients with solitary adenomas, the adenoma was demonstrated by ultrasound scans in 66%, by thallium-technetium scintigraphy in 83%, and by either test in 87%. Correct identification by ultrasonography was 59%; by thallium-technetium scintigraphy, 75%; and together, 73%. Of 6 patients with multiple-gland disease, 2 were correctly identified by localization tests and 9 of 15 abnormal glands were demonstrated. Of the 43 unilateral explorations, 43 single adenomas and no cases of multiple-gland disease were identified; of the 57 bilateral explorations, 51 single adenomas and 6 cases of multiple-gland disease were identified. No complications occurred in either group. Hypercalcemia persisted in 3 patients who underwent bilateral exploration and recurrent hypercalcemia developed in 1 patient in each group. The average operative time for the unilateral procedure was 105 minutes, and for the bilateral procedure, 184 minutes (P < .001). Since 1994, 31 (66%) of 47 patients have had unilateral exploration based on correct localization tests. CONCLUSIONS: Unilateral exploration that is based on the results of localization tests requires less operative time and produces results similar to bilateral exploration.

Adenoma↗
PubMed1997

Effectiveness and safety of 100 consecutive parathyroidectomies.

BACKGROUND AND METHODS: In order to evaluate the indications for operation for patients with primary hyperparathyroidism, prospective information was gathered on 100 consecutively operated patients from 1991 to 1996. A standard evaluation for outcomes and patient satisfaction was instituted. Patients consisted of 73 women and 27 men. Major symptoms existed in 48 patients, and 52 patients were referred to as "asymptomatic" because they fit the National Institutes of Health Consensus Development Conference Statement with abnormal laboratory values. The pathology was 94 single adenomas, 4 double adenomas, and 2 cases of hyperplastic multiglandular disease. RESULTS: All 100 patients had abnormal parathyroids removed, resulting in normocalcemia in 97. Three patients had persistent hypercalcemia until a second operation removed additional abnormal parathyroids, resulting in normocalcemia. No operative complications or mortality occurred. Overnight stay occurred in 88 patients. During long-term follow-up of patients, only 2 developed recurrent hyperparathyroidism. When asked whether the operation improved their health, 94% of patients with major symptoms and 72% of asymptomatic patients responded affirmatively. CONCLUSION: Parathyroidectomy is an efficient and safe operation with excellent normalization of serum calcium and a high rate of patient satisfaction.

Adolescent↗
PubMed1997

Cavernous hemangiomas of the liver: enlargement over time.

OBJECTIVE: It has been reported that cavernous hemangiomas of the liver either do not enlarge over time, or, of the very few lesions that have shown an increase in diameter on follow-up imaging studies, the increase has been minimal. The objective of this paper is to report growth of four cavernous hemangiomas that were shown to have doubled to tripled in diameter on follow-up imaging studies done between 34 months and 10.5 years after the initial diagnosis. CONCLUSION: This report indicates that hepatic hemangiomas can grow significantly in diameter, although such growth is unusual. Despite the growth of the lesion, however, if the imaging features are characteristic of hemangioma an imaging diagnosis can still be made confidently.

Adult↗