Reducing scanning electron microscope charging by using exponential contrast stretching technique on post-processing images

An exponential contrast stretching (ECS) technique is developed to reduce the charging effects on scanning electron microscope images. Compared to some of the conventional histogram equalization methods, such as bi-histogram equalization and recursive mean-separate histogram equalization, the proposed ECS method yields better image compensation. Diode sample chips with insulating and conductive surfaces are used as test samples to evaluate the efficiency of the developed algorithm. The algorithm is implemented in software with a frame grabber card, forming the front-end video capture element.

Incidence of post-operative troponin I rises and 1-year mortality after emergency orthopaedic surgery in older patients

OBJECTIVES

to determine the incidence of post-operative troponin I rises and its association with 1-year all-cause mortality and cardiac events after emergency orthopaedic-geriatric surgery, which has not been studied before.

METHODS

one hundred and two patients over the age of 60 were recruited and followed up at 1 year. All consented to serial troponin I measurements peri-operatively.

RESULTS

the incidence of a troponin I rise post-operatively was 52.9%. Post-operative acute myocardial infarction was diagnosed in 9.8% and at 1 year, 70% of these patients were dead. At 1 year, 32.4% (33/102) had sustained a cardiac event (myocardial infarction, congestive cardiac failure, atrial fibrillation or major arrhythmia) and using multivariate analysis, post-operative troponin rise (OR 3.9, 95% CI 1.4-10.7, P = 0.008) was an independent predictor of this. Half of the patients with a troponin rise had a cardiac event compared to 18.8% without a rise. All-cause mortality was 20.6% at 1 year; 37% with an associated post-operative troponin rise died versus 2.1% without a rise (P < 0.0001). Using multivariate analysis, only two factors were associated with 1-year all-cause mortality: post-operative troponin rise (OR 12.0, 95% CI 1.4-104.8, P = 0.025) and sustaining a post-operative in-hospital cardiac event (OR 6.6, 95% CI 1.7-25.6, P = 0.006). Furthermore, patients with higher troponin levels had significantly worse survival.

CONCLUSIONS

there is a high incidence of post-operative troponin I rises in older patients undergoing emergency orthopaedic surgery with 1-year mortality and cardiac events being significantly increased in these patients. Future studies are needed to determine whether any intervention can improve outcome for these patients.

Description of an orthopedic-geriatric model of care in Australia with 3 years data

AIM

Orthopedic-geriatric units have been established worldwide to improve the care of older patients admitted with fractures. This study describes one type of orthopedic-geriatric model which has been implemented in Victoria, Australia, named the Orthopedic Aged Care and Rehabilitation Service (OARS) and evaluates patient characteristics and outcomes including inpatient mortality.

METHODS

Eight hundred and thirty-four consecutive admissions under OARS between May 2003 and May 2006 were analyzed.

RESULTS

Mean age was 76.6 years, the majority of patients were female (73%) and had come from home (77%). Fractured neck of femur represented 51% of all fractures managed by OARS followed by lower limb fractures (20%) and upper limb fractures (13%). The majority of patients required inpatient rehabilitation (49% of patients overall and 61% specifically for fractured neck of femur). Inpatient mortality for all fractures was 2.5% and specifically 3.5% for fractured neck of femur.

CONCLUSION

The OARS model involves close liaison between orthopedic and geriatric teams and promotes a multidisciplinary approach. Mortality rate for fractured neck of femur was lower than the state average, suggesting that combined orthopedic-geriatric care can improve outcomes.

Image signal-to-noise ratio estimation using Shape-Preserving Piecewise Cubic Hermite Autoregressive Moving Average model

We propose to cascade the Shape-Preserving Piecewise Cubic Hermite model with the Autoregressive Moving Average (ARMA) interpolator; we call this technique the Shape-Preserving Piecewise Cubic Hermite Autoregressive Moving Average (SP2CHARMA) model. In a few test cases involving different images, this model is found to deliver an optimum solution for signal to noise ratio (SNR) estimation problems under different noise environments. The performance of the proposed estimator is compared with two existing methods: the autoregressive-based and autoregressive moving average estimators. Being more robust with noise, the SP2CHARMA estimator has efficiency that is significantly greater than those of the two methods.

Gene expression profiling suggests primary central nervous system lymphomas to be derived from a late germinal center B cell

To characterize the molecular origin of primary lymphomas of the central nervous system (PCNSL), 21 PCNSLs of immunocompetent patients were investigated by microarray-based gene expression profiling. Comparison of the transcriptional profile of PCNSL with various normal and neoplastic B-cell subsets demonstrated PCNSL (i) to display gene expression patterns most closely related to late germinal center B cells, (ii) to display a gene expression profile similar to systemic diffuse large B-cell lymphomas (DLBCLs) and (iii) to be in part assigned to the activated B-cell-like (ABC) or the germinal center B-cell-like (GCB) subtype of DLBCL.

Primary progressive aphasia: a case report

Primary progressive aphasia is a progressive neurodegenerative disorder characterised by deterioration in language function while other higher centre functions are relatively preserved initially. The diagnosis is made based on clinical presentation, linguistic testing and imaging, both functional and structural. Survival is similar to other dementias and the main form of intervention is speech therapy. We describe a case of primary progressive aphasia in a Vietnamese man with corresponding changes on positron emission tomography.

Real-time image quality assessment with mixed Lagrange time delay estimation autoregressive (MLTDEAR) model

A proposal to assess the quality of scanning electron microscope images using mixed Lagrange time delay estimation technique is presented. With optimal scanning electron microscope scan rate information, online images can be quantified and improved. The online quality assessment technique is embedded onto a scanning electron microscope frame grabber card for real-time image processing. Different images are captured using scanning electron microscope and a database is built to optimally choose filter parameters. An optimum choice of filter parameters is obtained. With the optimum choice of scan rate, noise can be removed from real-time scanning electron microscope images without causing any sample contamination or increasing scanning time.

Implementing evidence-based guidelines: inpatient management of chronic obstructive pulmonary disease

BACKGROUND

Evidence-based guidelines exist to guide inpatient management of chronic obstructive pulmonary disease (COPD) exacerbations, but we do not know how well these recommendations are adhered to.

AIMS

The aims of this study were: (i) to examine concordance with evidence based guidelines for inpatient management of COPD and (ii)to address deficiencies in compliance with guidelines by feedback of audit results and distribution of an education package.

METHODS

Retrospective chart reviews were performed using a data collection tool based on current guidelines. Forty-nine consecutive COPD admissions were audited, and results presented to medical staff. An education package was distributed directly after the presentation. One month later,35 consecutive separations were reviewed. Concordance with recommendations supported by the highest level of evidence was calculated.

RESULTS

Data were complete for 84 cases. Concordance rates ranged from 0 to 100%. Apart from initiation of systemic steroids (80-83%)and avoidance of intravenous aminophylline (100%),concordance rates were less than 60%. The only significant improvement post-intervention was for steroid duration (10 vs 29%,95% confidence interval for difference (-36.2, -1.8)).

CONCLUSION

Recommendations for steroid initiation and avoidance of aminophylline are well adhered to. Concordance rates for other recommendations were generally less than 60%. Concordance with recommendations for steroid duration was significantly improved by our intervention. The findings suggest that to facilitate evidence-based practice, alternative interventions should be evaluated.

Low-dose intravenous methylprednisolone or conservative treatment in the management of traumatic optic neuropathy

PURPOSE

To compare the efficacy of low-dose intravenous methylprednisolone or conservative treatment in the management of traumatic optic neuropathy.

METHODS

A non-randomized retrospective study of 21 patients (21 eyes) with traumatic optic neuropathy treated between October 95 and November 97 in a tertiary ophthalmology unit. Traumatic optic neuropathy was defined as traumatic visual loss with afferent pupillary defect in the absence of direct injury to the globe or optic nerve. The median follow-up period was one year. Nine patients were treated with 125-250 mg methylprednisolone 6-hourly intravenously for a mean of 3.3 days (range 2-5 days) and 12 patients were treated conservatively. Visual acuity (VA) was measured with a Snellen chart before and after treatment at each follow-up visit. Visual recovery was defined as an improvement of 2 or more Snellen lines one week post-injury or later.

RESULTS

The patients' mean age was 37.1 years (range 12-65 years). There were more males (90.5%) than females (9.5%). Traumatic optic neuropathy was in 12 right eyes and 9 left eyes. The cause of injury included traffic accidents (52.4%), falls (28.6%), assault (14.2%) and others (4.8%). The mean interval between the injury and steroid therapy was 3.6 days (range 1-11 days). Visual recovery was observed in 44.4% of eyes treated with methylprednisolone and in 33.3% treated conservatively (p = 0.673, Fisher's exact test).

CONCLUSIONS

Intravenous methylprednisolone at the dosage and duration used in this retrospective study did not significantly improve the visual recovery of eyes with traumatic optic neuropathy compared to conservative treatment. However, this small sample may not be sensitive enough to detect a small difference in visual recovery rates, and further studies with larger samples may be warranted.

Melioidosis of the head and neck

Melioidosis is a potentially deadly infection that can affect any organ system. Reports of melioidosis of the ENT/head and neck region are relatively uncommon. Four cases are presented: (i) parotid abscess evolving into necrotising fasciitis, (ii) acute sinusitis and parapharyngeal cellulitis resulting in upper airway obstruction, (iii) acute suppurative lymphadenitis (iv) and chronic suppurative otitis media causing meningoencephalitis. Three of the four cases are believed to be unique, as a literature review of melioidosis in ENT/head and neck is also presented. Some practical issues of management are also discussed. Not suspecting melioidosis does not change contemporary empirical broadspectrum antibiotic therapy. The value of suspicion or on confirmation of diagnosis lies in anticipating and planning for rapid change.

Homodimers of mutant tryptophan synthase alpha-subunits in Escherichia coli

Tryptophan synthase alpha-subunit from Escherichia coli functionally exists as a heterotetramer of alpha(2)beta(2) with beta-subunit. While wild-type and mutant (F139W, T24M/F139W, and T24L/F139W) alpha-subunits were expressed as a monomer from recombinant plasmids in Escherichia coli, T24A/F139W, T24S/F139W, and T24K/F139W mutant alpha-subunits were abnormally expressed as soluble homodimers in addition to monomers. Monomers of dimer-forming mutant alpha-subunits retain high affinity to beta-subunit, high activity in stimulating catalytic activities of beta-subunit, and nearly intact content of secondary structure, indicating that the global structures of these monomers are identical to that of F139W alpha-subunit. However, fluorescence spectra of Trp139 and ANS binding indicate that significant perturbations occur in the mutant proteins. Interestingly, these defective properties of monomers caused by residue replacement were partially repaired by the dimer formation. As a result, it is suggested that dimers may be formed by domain or loop swapping, and that residue 24 may play important role in maintaining on-pathway of alpha-subunit folding.

The activation of PI 3-K and PKC zeta in PMA-induced differentiation of HL-60 cells

The human myelocytic leukemia cell line HL-60 is a useful model for the study of cellular differentiation. Phorbol 12-myristate 13-acetate (PMA) induces the monocyte/macrophage-like differentiation of HL-60 cells and results in growth arrest, increasing adherence. In PMA-induced differentiation of HL-60 cells, phosphoinositide 3-kinase (PI 3-K) activity was measured as phosphatidylinositol3P recovery from phosphatidylinositol by in vitro kinase assay. PI 3-K activity was increased in HL-60 cells that were stimulated by 20 nM PMA and the activity was inhibited by pretreatment with 20 microM LY294002, a specific inhibitor of PI 3-K. Members of the protein kinase C (PKC) family have been suggested to be one of the downstream targets of PI 3-K. PKC zeta is one of the atypical PKCs, non-diacylglycerol-responsive PKCs, and the activity was measured by the ability of phosphorylation onto myelin basic protein. PMA also induced the activation of PKC zeta during monocytic differentiation of HL-60 cells, and LY294002-pretreated cells failed to induce PKC zeta activation. The activity of PI 3-K is essential for PKC zeta activation, and LY294002 blocks both monocytic differentiation of HL-60 cells and activation of PKC zeta during PMA-induced cell differentiation. This implies that activated PI 3-K subsequently stimulates the PKC zeta in the process of PMA-induced monocytic differentiation.

Receptor-G protein gamma specificity: gamma11 shows unique potency for A(1) adenosine and 5-HT(1A) receptors

G protein coupled receptors activate signal transducing guanine nucleotide-binding proteins (G proteins), which consist of an alpha subunit and a betagamma dimer. Whole cell studies have reported that receptors signal through specific betagamma subtypes. Membrane reconstitution studies with the adenosine A(1) and alpha(2A) adrenergic receptors have reached a similar conclusion. We aimed to test the generality of this finding by comparing the gamma subtype specificity for four G(i)-coupled receptors: alpha(2A) adrenergic; A1 adenosine (A(1)-R); 5-hydroxytryptamine(1A) (5-HT(1A)-R); mu opioid. Membranes were reconstituted with Galpha(i)(1) and five gamma subtypes (dimerized to beta1). Using a sensitive alpha-betagamma binding assay, we show that all recombinant betagamma (except beta1gamma1) had comparable affinity for alpha(i)(1). Using high affinity agonist binding as a measure of receptor-G protein coupling, betagamma-containing gamma11 was the most potent for A(1)-R and 5-HT(1A)-R (p < 0.05, one way ANOVA) while gamma7 was most potent for the other two receptors. gamma11 was 3-8-fold more potent for the A(1)-R than were the other gamma subtypes. Also, gamma11 was 2-8-fold more potent for A(1)-R than at the other receptors, suggesting a unique coupling specificity of the A(1)-R for gamma11. In contrast, the discrimination by receptors for the other betagamma subtypes (beta1 and gamma1, gamma2, gamma7, and gamma10) was limited (2-3-fold). Thus the exquisite betagamma specificity of individual receptors reported in whole cell studies may depend on in vivo mechanisms beyond direct receptor recognition of betagamma subtypes.

An oil spill-food chain interaction model for coastal waters

An oil spill-food chain interaction model, composed of a multiphase oil spill model (MOSM) and a food chain model, has been developed to assess the probable impacts of oil spills on several key marine organisms (phytoplankton, zooplankton, small fish, large fish and benthic invertebrates). The MOSM predicts oil slick thickness on the water surface; dissolved, emulsified and particulate oil concentrations in the water column; and dissolved and particulate oil concentrations in bed sediments. This model is used to predict the fate of oil spills and transport with respect to specific organic compounds, while the food chain model addresses the uptake of toxicant by marine organisms. The oil spill-food chain interaction model can be used to assess the environmental impacts of oil spills in marine ecosystems. The model is applied to the recent Evoikos-Orapin Global oil spill that occurred in the Singapore Strait.

Management of haemorrhagic stroke with hyperbaric oxygen therapy--a case report

Hyperbaric oxygen therapy (HBOT) has been used in the treatment of cerebral ischaemia with positive effects on tissue oxygenation. We present a case of haemorrhagic stroke treated successfully with HBOT and review the literature on its role in cerebrovascular disease.

Selective inactivation of guanine-nucleotide-binding regulatory protein (G-protein) alpha and betagamma subunits by urea

G-protein-coupled receptors activate signal-transducing G-proteins, which consist of an alpha subunit and a betagamma dimer. Membrane extraction with 5-7 M urea has been used to uncouple receptors from endogenous G-proteins to permit reconstitution with purified G-proteins. We show that alpha(i) subunits are inactivated with 5 M urea whereas the betagamma dimer requires at least 7 M urea for its inactivation. There is no significant loss of receptors. Surprisingly, Western-blot analysis indicates that the urea-denatured alpha(i) subunit remains mostly membrane-bound and that beta is only partially removed. After 7 M urea treatment, both alpha(i1) and betagamma subunits are required to restore high-affinity agonist binding and receptor-catalysed guanosine 5'-[gamma-thio]triphosphate binding. We demonstrate the generality of this approach for four G(i)-coupled receptors (alpha(2A)-adrenergic, adenosine A1, 5-hydroxytryptamine(1A) and mu-opioid) expressed in insect cells and two mammalian cell lines. Thus a selectivity of urea for G-protein alpha versus betagamma subunits is established in both concentration and mechanism.

Automated static perimetry: the influence of myopia and its method of correction

OBJECTIVE

To determine how the magnitude of myopia and its method of correction influence visual field testing.

DESIGN

Prospective observational case series, including comparison of spectacles and contact lenses.

PARTICIPANTS

One hundred forty-six ophthalmologically normal males 19 to 24 years of age with myopia (spherical equivalent from -0.50 to -14.0 diopters).

METHODS

Participants performed automated static threshold perimetry. Refractive errors were corrected using trial lenses and soft contact lenses. Subjects were tested with both methods of correction, the order of which was randomized.

MAIN OUTCOME MEASURES

Threshold sensitivity and global indexes.

RESULTS

Only one subject (0.7%) had a significant reproducible visual field defect on both methods of correction. Six subjects (4.1%) had a focal visual field defect on one method of correction but not the other. For myopia greater than -4.0 diopters, the mean defect decreased significantly as axial length and degree of myopia increased (P: < 0.01). Similar results were obtained with either method of correction.

CONCLUSIONS

Threshold sensitivity is reduced in moderate and high myopia, regardless of the method of correction. The surprisingly low prevalence of visual field defects in this myopic population disputes the widely held view that myopia is associated commonly with visual field abnormalities. If field defects are found in myopes on automated perimetry, it is advisable to repeat the test with another method of optical correction to check that such defects are genuine and not related to the method of refractive correction.

Coupling efficacy and selectivity of the human mu-opioid receptor expressed as receptor-Galpha fusion proteins in Escherichia coli

Two constructs encoding the human micro-opioid receptor (hMOR) fused at its C terminus to either one of two Galpha subunits, Galpha(o1) (hMOR-Galpha(o1)) and Galpha(i2) (hMOR-Galpha(i2)), were expressed in Escherichia coli at levels suitable for pharmacological studies (0.4-0.5 pmol/mg). Receptors fused to Galpha(o1) or to Galpha(i2) maintained high-affinity binding of the antagonist diprenorphine. Affinities of the micro-selective agonists morphine, [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO), and endomorphins as well as their potencies and intrinsic activities in stimulating guanosine 5'-O-(3-[(35)S]thiotriphosphate) ([(35)S]GTPgammaS) binding were assessed in the presence of added purified Gbetagamma subunits. Both fusion proteins displayed high-affinity agonist binding and agonist-stimulated [(35)S]GTPgammaS binding. In the presence of Gbetagamma dimers, the affinities of DAMGO and endomorphin-1 and -2 were higher at hMOR-Galpha(i2) than at hMOR-Galpha(o1), whereas morphine displayed similar affinities at the two chimeras. Potencies of the four agonists in stimulating [(35)S]GTPgammaS binding at hMOR-Galpha(o1) were similar, whereas at hMOR-Galpha(i2), endomorphin-1 and morphine were more potent than DAMGO and endomorphin-2. The intrinsic activities of the four agonists at the two fusion constructs were similar. The results confirm hMOR coupling to Galpha(o1) and Galpha(i2) and support the hypothesis of the existence of multiple receptor conformational states, depending on the nature of the G protein to which it is coupled.

Involvement of SPARC in in vitro differentiation of skeletal myoblasts

SPARC (secreted protein acidic and rich in cysteine) is an extracellular Ca(2+)-binding glycoprotein associated with the morphogenesis and remodeling of various tissues. Here, involvement of SPARC in the myogenesis of skeletal myoblasts was investigated in vitro. First, the differential expression of SPARC mRNA during the myogenesis was initially identified by a differential display reverse transcription (DDRT)-PCR method. The expression of the SPARC gene was significantly up-regulated during the differentiation of C2C12 mouse myoblasts. Second, the treatment with anti-SPARC antibody almost completely prevented the differentiation of myoblasts. Third, the treatment with EGTA, a Ca(2+) chelator that is known to inhibit the fusion of C2C12 myoblasts, reversibly inhibited the up-regulation of SPARC gene expression. On the other hand, the treatment with A23187, a Ca(2+) ionophore, rapidly and dramatically increased the level of SPARC transcript. Taken together, these results suggest that SPARC may play a critical role(s) in the morphological change of myoblasts, and that the expression of SPARC gene may be controlled by Ca(2+)-dependent pathway in myogenesis.