Characterizing the geometry of InAs nanowires using mirror electron microscopy.

Mirror electron microscopy (MEM) imaging of InAs nanowires is a non-destructive electron microscopy technique where the electrons are reflected via an applied electric field before they reach the specimen surface. However strong caustic features are observed that can be non-intuitive and difficult to relate to nanowire geometry and composition. Utilizing caustic imaging theory we can understand and interpret MEM image contrast, relating caustic image features to the properties and parameters of the nanowire. This is applied to obtain quantitative information, including the nanowire width via a through-focus series of MEM images.

Direct-to-participant feedback and awareness of bone mineral density testing results in a population-based sample of mid-aged Canadians.

UNLABELLED: This population-based study of mid-aged Canadians assessed awareness of diagnosis by bone mineral density (BMD) following dual-energy X-ray absorptiometry (DXA) testing and compared the effects of feedback only to the physician with direct-to-participant feedback. Poor recall of osteoporosis results was observed irrespective of the feedback destination, but direct-to-participant feedback improved recall of borderline or normal results. INTRODUCTION: BMD testing provides information about fracture risk. This study assessed whether awareness of results, in a random population sample of mid-aged Canadians, differed if results were provided to physicians only or directly to participants. METHODS: Prospective cohort study of 2,678 women and men aged 40-60 years from the Canadian Multicentre Osteoporosis Study. Participants completed hip and spine DXA and interviewer-administered questionnaires regarding demographics and osteoporosis risk factors. Lateral spine X-rays were conducted on those > or =50 years of age. All test results were reported to the participant, the family physician or both. Associations between BMD results, feedback destination and correct self-report results, 3 years later, were assessed using logistic regression while adjusting for potential confounders. RESULTS: Only 25% of men and 33% of women correctly reported their osteoporosis diagnoses. Direct-to-participant vs. physician-only reports did not improve recall of osteoporosis diagnosis but improved recall of borderline or normal BMD. Older (vs. younger) men and men with prevalent vertebral fractures demonstrated better recall of their osteoporosis diagnosis. CONCLUSIONS: Recall of low BMD results was poor, despite direct-to-participant feedback and even in the presence of other osteoporosis risk factors. Direct-to-participant feedback may improve awareness of borderline or normal BMD results.

Early changes in respiratory health in trades' apprentices and physician visits for respiratory illnesses later in life.

OBJECTIVES: An inception cohort of trades' apprentices had rapid declines in lung function (forced expiratory volume in 1 s (FEV(1))) and rapid increases in bronchial responsiveness ( upward arrowBR) over the first 2 years of employment. We used physician visit data to assess respiratory health over the following 13 years. METHODS: Construction painter, electrician, insulator and machinist apprentices beginning at a British Columbia trade school in 1988 were invited to participate and were followed up 2 years later. Subjects were linked to provincial medical databases to examine physician visits for asthma and other respiratory illnesses for the 13 years following. Multivariable models with rapid decline in FEV(1) and rapid increase in BR from years 1 to 3 were constructed. Respiratory symptoms were also examined as predictors of visit rates and meeting a case definition (for asthma or other respiratory illness). RESULTS: The cohort included 281 apprentices (97% are men). Sixteen subjects met the asthma case definition (>or=2 visits coded as asthma in 1 year) and 20 met the other respiratory illness case definition (>or=3 visits for bronchitis, emphysema, respiratory symptoms in 1 year). In models controlling for demographic factors and smoking, subjects with bronchitis symptoms at baseline were more likely to develop other respiratory illness during follow-up (RR 4.4, 95% CI 1.6 to 11.9). Apprentices who developed asthma symptoms over the first 2 years were approximately six times more likely to become asthma cases (95% CI 1.9 to 18.8). Those with a rapid increase in BR were at increased risk of becoming asthma cases (RR 5.5, 95% CI 1.9 to 16.1), as well as having higher asthma visit rates (RR 6.5). Subjects with rapid decline in FEV(1) were 3.2 times more likely to become asthma cases (95% CI 0.8 to 12.1). CONCLUSIONS: Changes in respiratory health early in adulthood, especially increased BR, are associated with respiratory physician visits. These findings are important for workplace screening and prevention and also suggest that physician visit databases are promising research tools in respiratory epidemiology.

A retrospective assessment of occupational noise exposures for a longitudinal epidemiological study.

OBJECTIVES: Chronic exposure to high levels of noise may be associated with increased risk of cardiovascular disease. We therefore undertook a quantitative retrospective exposure assessment using predictive statistical modelling to estimate historical exposures to noise among a cohort of 27,499 sawmill workers as part of an investigation of acute myocardial infarction mortality. METHODS: Noise exposure data were gathered from research, industry and regulatory sources. An exposure data matrix was defined and exposure level estimated for job title/mill/time period combinations utilising regression analysis to model determinants of noise exposure. Cumulative exposure and duration of exposure metrics were calculated for each subject. These were merged with work history data, and exposure-response associations were tested in subsequent epidemiological studies, reported elsewhere. RESULTS: Over 14,000 noise measurements were obtained from British Columbia sawmills. A subset, comprising 1901 full-shift dosimetry measurements from cohort mills was used in producing a predictive model (R(2) = 0.51). The model was then used to estimate noise exposures for 3809 "cells" of an exposure data matrix representing 81 jobs at 14 mills over several decades. Various exposure metrics were then calculated for subjects; mean cumulative exposure was 101 dBA*year. Mean durations of employment in jobs with exposure above thresholds of 85, 90 and 95 dBA, were 9.9, 7.0 and 3.2 years, respectively. CONCLUSIONS: The utility of predictive statistical modelling for occupational noise exposure was demonstrated. The model required input data that were relatively easily obtained, even retrospectively. Remaining issues include adequate handling of the use of hearing protectors that likely bias exposure estimation.

Risks for the development of outcomes related to occupational allergies: an application of the asthma-specific job exposure matrix compared with self-reports and investigator scores on job-training-related exposure.

BACKGROUND AND AIM: Risks for development of occupational sensitisation, bronchial hyper-responsiveness, rhinoconjunctival and chest symptoms at work associated with continued exposure to high molecular weight (HMW) allergens were estimated with three exposure assessment methods. METHODS: A Cox regression analysis with adjustment for atopy and smoking habit was carried out in 408 apprentices in animal health technology, pastry making, and dental hygiene technology with an 8-year follow-up after training. The risk of continued exposure after training, estimated by the asthma-specific job exposure matrix (JEM), was compared with self-reports and investigator scores on job-training-related exposure. Associations between outcomes and work duration in job(s) related to training were also evaluated. RESULTS: Exposure to animal-derived HMW allergens, subsequent to the apprenticeship period, as estimated by the JEM, was associated with a significantly increased risk for occupational sensitisation (hazard ratio (HR) 6.4; 95% CI 2.3 to 18.2) and rhinoconjunctival symptoms at work (HR 2.6; 95% CI 1.1 to 6.2). Exposure to low molecular weight (LMW) agents significantly increased the risk of developing bronchial hyper-responsiveness (HR 2.3; 95% CI 1.1 to 5.4). Exposure verification appeared to be important to optimise the sensitivity and the specificity, as well as HRs produced by the JEM. Self-reports and investigator scores also indicated that further exposure to HMW allergens increased the risk of developing occupational allergies. The agreement between self-reports, investigator scores, and the JEM were moderate to good. There was no significant association between respiratory outcomes and work duration in jobs related to training. CONCLUSION: The asthma-specific JEM could estimate the risk of various outcomes of occupational allergies associated with exposure to HMW and LMW allergens, but it is relatively labour intensive. Exposure verification is an important integrated step in the JEM that optimised the performance of the matrix.

Quantification of electroporative uptake kinetics and electric field heterogeneity effects in cells.

We have conducted experiments quantitatively investigating electroporative uptake kinetics of a fluorescent plasma membrane integrity indicator, propidium iodide (PI), in HL60 human leukemia cells resulting from exposure to 40 mus pulsed electric fields (PEFs). These experiments were possible through the use of calibrated, real-time fluorescence microscopy and the development of a microcuvette: a specialized device designed for exposing cell cultures to intense PEFs while carrying out real-time microscopy. A finite-element electrostatic simulation was carried out to assess the degree of electric field heterogeneity between the microcuvette's electrodes allowing us to correlate trends in electroporative response to electric field distribution. Analysis of experimental data identified two distinctive electroporative uptake signatures: one characterized by low-level, decelerating uptake beginning immediately after PEF exposure and the other by high-level, accelerating fluorescence that is manifested sometimes hundreds of seconds after PEF exposure. The qualitative nature of these fluorescence signatures was used to isolate the conditions required to induce exclusively transient electroporation and to discuss electropore stability and persistence. A range of electric field strengths resulting in transient electroporation was identified for HL60s under our experimental conditions existing between 1.6 and 2 kV/cm. Quantitative analysis was used to determine that HL60s experiencing transient electroporation internalized between 50 and 125 million nucleic acid-bound PI molecules per cell. Finally, we show that electric field heterogeneity may be used to elicit asymmetric electroporative PI uptake within cell cultures and within individual cells.

Droplet Epitaxy Image Contrast in Mirror Electron Microscopy.

Image simulation methods are applied to interpret mirror electron microscopy (MEM) images obtained from a movie of GaAs droplet epitaxy. Cylindrical symmetry of structures grown by droplet epitaxy is assumed in the simulations which reproduce the main features of the experimental MEM image contrast, demonstrating that droplet epitaxy can be studied in real-time. It is therefore confirmed that an inner ring forms at the droplet contact line and an outer ring (or skirt) occurs outside the droplet periphery. We believe that MEM combined with image simulations will be increasingly used to study the formation and growth of quantum structures.

Considering risks to healthcare workers from glutaraldehyde alternatives in high-level disinfection.

Due to concerns over glutaraldehyde's toxicity, two substitutes have recently been introduced; ortho-phthalaldehyde (OPA), and a mixture of hydrogen peroxide and peracetic acid. There is limited information about the health effects for employees from these products. This study assesses the current practices regarding the use of high-level disinfectants in British Columbian hospitals and predicts the relative toxicities of each product. Industry practices were compiled using a comprehensive survey of current practices and decision processes in all hospitals in British Columbia. Of 95 hospitals, 64 returned surveys; 80% of these used high-level disinfection. Among user hospitals, 49% used glutaraldehyde alone and 51% had introduced alternatives. Concern about staff health was the most common reason for substituting, but this was frequently not considered when choosing specific alternatives. Hospitals that involved occupational health, infection control or regional staff in high-level disinfectant decisions used glutaraldehyde alternatives less often. In most hospitals, it was difficult to find individuals who were knowledgeable about the use of disinfectants. Potential health effects associated with each type of high-level disinfectant were assessed by review of the published literature and available manufacturers' data along with qualitative structure-activity relationship analysis. Results indicated that although all products irritate the skin and respiratory tract, OPA is a potential dermal and respiratory sensitizer but hydrogen peroxide and peracetic acid do not cause allergic reactions. Despite little being known about the risks to employees from glutaraldehyde alternatives, their use is widespread. The potential risks of all high-level disinfectants are serious; thus regulators and users are faced with important risk management decisions before and after they have been introduced into the workplace.

IL-1beta mediates diethyldithiocarbamate-induced granulocyte colony-stimulating factor production and hematopoiesis.

Diethyldithiocarbamate (DDTC) exhibits chemoprotective effects via reduced myelosuppression in mice treated with various chemotherapeutic agents. The mechanism of DDTC-mediated chemoprotection is believed to involve the induction and release of several cytokines, including interleukin-1 beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and granulocyte colony-stimulating factor (G-CSF). In the present study the roles of IL-1beta and TNF-alpha in DDTC-mediated G-CSF induction were examined using human long-term bone marrow cultures (hLTBMCs). Administration of IL-1 receptor antagonist (IL-1ra) to DDTC-treated hLTBMCs obviated the G-CSF induction profile and blocked the resultant colony proliferation, indicating that IL-1beta mediates DDTC-induced G-CSF release and hematopoiesis. IL-1beta mRNA levels were increased threefold over control following DDTC treatment of hLTBMCs, implying that DDTC induces IL-1beta at the level of transcription. Conversely, studies involving inhibition of DDTC-induced TNF-alpha synthesis, with the inhibitor MNX 160, had no effect on DDTC-induced G-CSF release or colony proliferation. These findings taken together strongly suggest that IL-1beta mediates the chemoprotective effects of DDTC.

Parathyroid hormone stimulation of calcium transport is mediated by dual signaling mechanisms involving protein kinase A and protein kinase C.

PTH stimulates calcium absorption by renal distal convoluted tubules. The PTH receptor is capable of coupling to adenylyl cyclase and phospholipase C. However, it is not known whether the actions of PTH require activation of both pathways. Three approaches were taken to identify the signaling pathways responsible for stimulating calcium entry in distal convoluted tubule cells: second messengers formed in response to PTH were identified, the effects on calcium uptake of inhibiting protein kinase A (PKA) or protein kinase C (PKC) with chemical or peptide blockers were determined, and calcium transport was reconstituted by the addition of exogenous second messengers. PTH increased cAMP formation in primary cultures of mouse distal and proximal tubule cells. However, PTH stimulated inositol trisphosphate formation only in proximal tubule cells. Blocking PKA with Rp-cAMPS or the cAMP-dependent protein kinase inhibitor inhibited PTH-stimulated Ca uptake. Likewise, the PKC inhibitors, calphostin C and PKC pseudosubstrate, inhibited PTH-induced calcium uptake. Addition of forskolin (30 nM) or phorbol 12-myristate 13-acetate (10 nM) alone had no effect on Ca uptake. However, when added in combination, Ca uptake was stimulated to nearly the same extent as with concentrations of PTH that maximally stimulate calcium transport. We conclude that stimulation of calcium uptake by distal convoluted tubule cells requires activation of both PKA and PKC.

Monoclonal antibodies raised to paraffin wax embedded archival tissue; feasibility study of their potential to detect novel antigenic markers.

A study to determine the feasibility of using archival paraffin wax embedded tissue to generate monoclonal antibodies is described. Specifically, monoclonal antibodies were raised to paraffin wax embedded normal human kidney tissue to test the possibility of producing antibodies to such tissue samples prior to attempting generation of antibodies to valuable archival tissue. Multiple sections (10 x 5 microm) were pooled and dewaxed as for immunohistochemical procedures and combined with Freund's adjuvant for immunization of BALB/c mice in vivo. Immunized spleen cells were fused with SP2 myeloma cells and subsequent clones screened on paraffin wax embedded normal human kidney sections, a range of cell lines and normal mouse tissue. Supernatants from 11 wells (from a total of 90 wells screened) showed different staining patterns on sections of paraffin wax embedded kidney. One clone, 1/11C, (isotype IgG1) which exhibited strong staining on all kidney tubules by immunohistochemical studies (glomeruli interstitium and vessels were unstained) and identified a band at 52 kDa on immunoblots of dewaxed kidney tissue (as used for immunogen) was chosen for further characterization. Immunoblotting of five mammalian cell lines showed differential expression of this 52 kDa band (distinct expression on 3/5, weak expression on 2/5 cell lines) whereas, all cell lines displayed a band at 44 kDa and a third band at 70 kDa was observed on 2/5 cell lines. In mouse tissue extracts, the 52 kDa band was identified in kidney tissue only (not in the lung, liver or spleen) with the 44 kDa and 70 kDa bands weakly expressed in all tissues. This preliminary investigation of a novel approach to identifying possible new antigenic markers or producing monoclonal antibodies which react better to known antigens on sections of paraffin wax embedded tissue showed that this method is feasible. The need to have a comprehensive screening system in place and the ability to identify potentially useful clones after the initial screening is paramount due to the relative scarcity of screening material (archival tissue sections) and the tedious nature of the screening method.

Macrophage accumulation of inhaled gallium-67 citrate in normal lungs.

Injected 67Ga has been used extensively to monitor inflammatory processes in the peripheral lung. We hypothesized that inhaled 67Ga may be useful in marking early airway inflammation in smokers. Eight nonsmokers and eight smokers breathed a 67Ga aerosol and imaging was performed immediately and 24 and 96 hr later. Approximately two-thirds of the initial dose remained in the lungs at 24 hr in both groups and no difference was seen between the groups. Only a very slight decrease was seen in both groups at 96 hr suggesting the gallium becomes bound to lung tissue or to cells not rapidly removed from the lungs. Autoradiography was performed on tissue from two smoke-exposed guinea pigs and two human patients undergoing resection surgery who breathed the gallium aerosol 24 hr prior to tissue removal. Silver grain accumulations were seen only over macrophages. We conclude that macrophage associated accumulation of 67Ga occurs in healthy lungs, and that it is not feasible to use aerosolized gallium to assess airway inflammation in smokers.

Immunocytochemical detection of Fcgamma receptors in human atherosclerotic lesions.

Much evidence indicates that atherosclerotic lesions are largely of an inflammatory nature. Activated macrophages and macrophage-derived foam cells laden with cholesterol esters are a major constituent of these lesions and can influence lesion formation via several potential mechanisms. One such mechanism is Fcgamma receptor activation and/or Fcgamma receptor-mediated clearance of immune complexes containing cholesterol, such as lipoprotein immune complexes. That this mechanism contributes to lesion formation would be further supported if Fcgamma receptor expression in arterial lesions were demonstrated. We therefore used monoclonal antibodies and immunocytochemical methods to analyze frozen sections of human arterial lesions for expression of each of the three primary classes of mononuclear phagocyte Fcgamma receptors. Approximately 800 sections of aorta, carotid, and coronary arteries obtained from five elderly donors were analyzed. The presence of macrophages was determined by assaying reactivity of a monoclonal antibody specific to CD163, which is expressed only on cells of the human mononuclear phagocyte lineage. Results indicate that highly cellular preatheromatous lesions contained numerous macrophages in the zone of proliferation that expressed each class of Fcgamma receptor (FcgammaRIA, FcgammaRIIA, and FcgammaRIIIA). Fcgamma receptor-positive cells were also present in medial and adventitial areas. Fcgamma receptor staining was both punctate and diffuse, the latter suggesting that soluble receptors were present in the extracellular matrix. These data further support that Fcgamma receptor-mediated clearance of immune complexes can occur in arterial lesions during atherogenesis. Expression of both the high affinity (FcgammaRIA) and lower affinity (FcgammaRIIA/FcgammaRIIIA) receptors indicates that mono- and multivalent IgG-containing immune complexes could engage Fcgamma receptors and influence lesion formation through several different inflammatory mechanisms triggered by receptor activation.

Single-step purification of epoxide hydrolase from rat liver microsomes using monoclonal-antibody chromatography.

Monoclonal antibody to rat liver microsomal epoxide hydrolase has been obtained after immunization of mice with the enzyme prepared by conventional methods. Antibody from ascitic fluid was purified and coupled to CNBr-activated Sepharose 4B, to give a specific affinity column. Monoclonal-antibody affinity chromatography provided a rapid single-step method of purifying to homogeneity active epoxide hydrolase from crude solubilized microsomes. The techniques used offer an effective method for characterization of a non-inhibitory monoclonal antibody.

Induction of UDP-glucuronyl transferase mRNA in embryonic chick livers by phenobarbital.

Administration of phenobarbital to chick embryos increased hepatic microsomal UDP-glucuroyltransferase activity some 25-fold. The large phenobarbital-induced increase of UDP-glucuronyltransferase activity was correlated to an equivalent increase of immunochemically measurable UDP-glucuronyltransferase protein. Poly(A+) RNA isolated from the livers of chick embryos treated with either phenobarbital or saline was translated in vitro. Immunochemical analysis of the translation products indicated that phenobarbital induced a 30-fold increase in UDP-GT mRNA. Fractionation of hepatic poly(A+) RNA from phenobarbital-treated chick embryos by sucrose density gradient centrifugation indicated that the size of the UDP-GT mRNA was 21S. These data show that phenobarbital induction of chick embryo liver UDP-glucuronyltransferase activity correlates with a similar large increase in the level of translatable mRNA for this enzyme.

Overexpression of the oncoprotein p53 in primary hepatic tumors of childhood does not correlate with gene mutations.

High levels of expression of the p53 protein and gene mutations have been described in adult hepatocellular carcinomas. It has been postulated that specific mutations in exon 7 may be caused by aflatoxin exposure. To determine whether p53 mutations occur in childhood liver cancer unassociated with aflatoxin exposure or hepatitis B virus (HBV) infection, we have analyzed three histologically distinct tumor types. Two techniques were used to access p53 in the tumors: (1) expression studies of the p53 protein were performed using the polyclonal antibody CM1 and immunohistochemistry, and (2) DNA sequencing was performed. p53 Protein was detectable by immunohistochemistry in 10 of 15 hepatoblastomas, six of nine hepatocellular carcinomas, and one of one embryonal sarcomas. Solid phase single-stranded DNA sequencing across exons 5 through 9 showed normal sequence in all cases. These results indicate that p53 is overexpressed in a majority of childhood liver cancers, but this abnormal p53 expression does not seem to be caused by mutations in the p53 gene.

MDR1 expression is associated with adverse survival in melanoma of the uveal tract.

Metastatic uveal melanoma is profoundly chemoresistant and has a very poor outcome. We have previously shown that the MDR1 gene and its gene product P-glycoprotein (P-gp), which are known to cause drug resistance in cancer cells, are expressed in ocular melanoma. Overexpression of MDR1 has been associated with a poor survival in some tumor types treated by chemotherapy and in some untreated tumours. To assess whether MDR1 expression is of prognostic value in uveal melanoma, we evaluated the expression of MDR1 by immunohistochemistry in 108 cases. Three semiquantitative grades were used to evaluate positive staining. We detected MDR1 expression in 80% of cases; 28% showed grade I staining; 30%, grade II staining; and 22%, grade III staining. There was a statistically significant association (P=.004) between MDR1 expression by tumor cells and shorter survival times (n=96), which was most striking at grade III levels of expression. Multivariate analysis showed that MDR1 expression is an independent prognostic indicator of poor survival. We conclude that (1) MDR1 may be involved in chemoresistance and tumor propagation in primary uveal melanoma, and (2) increasing levels of expression are prognostically significant and may prove a useful marker of tumor invasiveness, independent of established prognostic factors.

Collecting duct carcinoma of the kidney.

Collecting duct carcinoma is an unusual variant of renal cell carcinoma, whose appearance and behavior are not well established. We identified six cases of collecting duct carcinoma in our files. The clinical, pathologic, and immunohistochemical characteristics of these tumors are reported. The most common symptom was gross hematuria (four cases). Two patients had cervical adenopathy due to metastatic tumor. Four rapidly developed systemic metastases and died within 4 to 24 months. The primary renal tumors were located predominantly in the renal medulla and pelvis and had a partially cystic white-gray appearance. Histologic examination showed prominent tubulopapillary structures, nests of clear cells, and infiltrating tubules in a dense desmoplastic stroma. Atypical hyperplastic changes were found in some of the adjacent collecting ducts. Mucicarminophilic material was present in glandular elements in all six cases. Immunohistochemical studies revealed positivity with antibodies to epithelial membrane antigen, keratins, peanut agglutinin, vimentin, Leu M1 and lysozyme. The location of this tumor in the medulla, its distinctive histologic appearance, mucin positivity, expression of high molecular weight cytokeratins, and peanut agglutinin suggest that this is a distinct clinicopathologic entity which has an aggressive clinical course.

Clinical and socioeconomic features of subjects with red cedar asthma. A follow-up study.

A follow-up study of 128 subjects with red cedar asthma was conducted to evaluate the clinical and socioeconomic impact of the disease in determining the working status of the subjects after the diagnosis was made. The results suggest that the severity of asthma is not the main determinant of working status. Comparing the data at diagnosis and at follow-up examination, we found that the persistence of exposure resulted in a deterioration in the asthma despite the use of more medications. Subjects who were working were younger and had a larger number of dependents than the subjects who were not working at the time of the follow-up examination. We conclude that the socioeconomic factors are important in determining the working status of subjects with red cedar asthma. To prevent severe impairment and disability, there should be more economic incentives for these subjects to choose other jobs.

Conjunctival 'MALToma' with systemic recurrence.

We report the recurrence of a localized conjunctival lymphoma arising in mucosal-associated lymphoid tissue (MALToma) in the psoas muscle, 18 months after initial treatment with radiotherapy. Findings from systemic investigations demonstrated MALToma recurrences in the psoas muscle and the stomach. Ocular adnexal MALTomas typically manifest as localized tumors, which respond well to radiotherapy, but a proportion may recur in typical MALT sites. To our knowledge, this is the first report of a recurrence in the psoas muscle, and the clinical implication is that all patients with ocular adnexal lymphomas need to be followed up for an indefinite period.