Do health assets have a protective effect for hospitalized frail older adults?

BACKGROUND

Although increasing frailty is predictive of increased mortality and length of stay for hospitalized older adults, this approach ignores health assets that individuals can utilize to recover following hospital admission.

AIM

To examine whether health assets mitigate the effect of frailty on outcomes for older adults admitted to hospital.

DESIGN

Patients of 1418 aged ≥ 70 years admitted to 11 hospitals in Australia were evaluated at admission using the interRAI assessment system for Acute Care, which surveys a large number of domains, including cognition, communication, mood and behaviour, activities of daily living, continence, nutrition, skin condition, falls and medical diagnosis.

METHODS

The data set was interrogated for potential health assets and a multiple logistic regression adjusted for frailty index, age and gender as covariates was performed for the outcomes mortality, length of stay, re-admission and new need for residential care.

RESULTS

Inpatient mortality was 3% and 4.5% of patients died within 28 days of discharge. Median length of stay was 7 days (IQR 4-11). In multivariate analysis that includes frailty, being able to walk further [OR 0.08 (0.01-0.63)], ability to leave the house [OR 0.35 (0.17-0.74)] and living alone [OR 0.28 (0.10-0.79)] were protective against mortality. The presence of a support person was associated with a decreased length of stay [OR 0.14 (0.08-0.25)].

CONCLUSION

The inclusion of health assets in predictive models can improve prognostication and highlights potential interventions to improve outcomes for hospitalized older adults.

Medication adherence 1 month after hospital discharge in medical inpatients

BACKGROUND

The rate of medication non-adherence has been consistently reported to be between 20 and 50%. The majority of available data comes from international studies, and we hypothesised that a similar rate of adherence may be observed in Australian patients.

AIMS

To determine the rate of adherence to medications after discharge from acute general hospital admission and identify factors that may be associated with non-adherence.

METHODS

A prospective cohort study of 68 patients, comparing admission and discharge medication regimens to self-reported regimens 30-40 days after discharge from hospital. Patients were followed up via telephone call and univariate and multivariate binary logistic regression used to determine patient factors associated with non-adherence.

RESULTS

In all, 27 of 68 patients (39.7%) were non-adherent to one or more regular medications at follow up. Intentional and unintentional non-adherence contributed equally to non-adherence. Using multivariate analysis, presence of a carer responsible for medications was associated with significantly lower non-adherence (odds ratio (OR) 0.20 (0.05-0.83), P = 0.027) when adjusted for age, co-morbidities, chemist blister pack and total number of discharge medications.

CONCLUSIONS

Non-adherence to prescription medications is suboptimal and consistent with previous overseas studies. Having a carer responsible for medications is associated with significantly lower rates of non-adherence. Understanding patients' preferences and involving them in their healthcare may reduce intentional non-adherence.

Arrythmogenic Right Ventricular Dysplasia

A 10-year-old well and asymptomatic female was referred for screening of acute right ventricular dilatation (ARVD) as she had an elder brother diagnosed with ARVD whom died of sudden cardiac death. Electrocardiography (ECG), transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (CMR) were performed. Results of these investigations were suggestive of ARVD. Despite being a rare cardiac disease and largely unrecognised in children and young adult population, ARVD is an important cause of ventricular arrhythmias in this group of patients and is one of the causes of sudden cardiac death (SCD) in this population.

Stenting of vertical vein in an infant with obstructed supracardiac total anomalous pulmonary venous drainage

A 1.7 kg infant with obstructed supracardiac total anomalous pulmonary venous drainage (TAPVD) presented with severe pulmonary hypertension secondary to vertical vein obstruction. The child, in addition, had a large omphalocele that was being managed conservatively. The combination of low weight, unoperated omphalocele, and severe pulmonary hypertension made corrective cardiac surgery very high-risk. Therefore, transcatheter stenting of the stenotic vertical vein, as a bridge to corrective surgery was carried out. The procedure was carried out through the right internal jugular vein (RIJ). The stenotic segment of the vertical vein was stented using a coronary stent. After procedure, the child was discharged well to the referred hospital for weight gain and spontaneous epithelialization of the omphalocele. Stenting of the vertical vein through the internal jugular vein can be considered in very small neonates as a bridge to repair obstructed supracardiac total anomalous venous drainage.

JAK-STAT and G-protein-coupled receptor signaling pathways are frequently altered in epitheliotropic intestinal T-cell lymphoma

Epitheliotropic intestinal T-cell lymphoma (EITL, also known as type II enteropathy-associated T-cell lymphoma) is an aggressive intestinal disease with poor prognosis and its molecular alterations have not been comprehensively characterized. We aimed to identify actionable easy-to-screen alterations that would allow better diagnostics and/or treatment of this deadly disease. By performing whole-exome sequencing of four EITL tumor-normal pairs, followed by amplicon deep sequencing of 42 tumor samples, frequent alterations of the JAK-STAT and G-protein-coupled receptor (GPCR) signaling pathways were discovered in a large portion of samples. Specifically, STAT5B was mutated in a remarkable 63% of cases, JAK3 in 35% and GNAI2 in 24%, with the majority occurring at known activating hotspots in key functional domains. Moreover, STAT5B locus carried copy-neutral loss of heterozygosity resulting in the duplication of the mutant copy, suggesting the importance of mutant STAT5B dosage for the development of EITL. Dysregulation of the JAK-STAT and GPCR pathways was also supported by gene expression profiling and further verified in patient tumor samples. In vitro overexpression of GNAI2 mutants led to the upregulation of pERK1/2, a member of MEK-ERK pathway. Notably, inhibitors of both JAK-STAT and MEK-ERK pathways effectively reduced viability of patient-derived primary EITL cells, indicating potential therapeutic strategies for this neoplasm with no effective treatment currently available.

Effects of hospital-acquired conditions on length of stay for patients with diabetes

BACKGROUND

Inpatients with diabetes have longer length of stays (LOS). Understanding patterns of in-hospital complications between patients with diabetes and others may reveal measures to improve patient welfare and minimise LOS.

AIM

This study evaluates the rates and types of hospital-acquired conditions among patients with and without diabetes and assesses any effects on LOS.

METHODS

A total of 47 615 admission episodes from The Northern Hospital over 12 months was reviewed. Episodes were divided into four groups: (i) patients without diabetes; (ii) patients with diabetes without end-organ sequelae (EOS); (iii) patients with diabetes with EOS; and (iv) a subset of non-diabetic patients with a Charlson Co-morbidity score ≥1 (comparison group). The Classification of Hospital Acquired Diagnoses (CHADx) was applied to the groups to compare rates and types of inpatient complications. Linear regression was used to analyse the impact of the number of CHADx on LOS.

RESULTS

Almost 30% of admissions of patients with diabetes and EOS had at least one CHADx, compared with 13% for non-diabetes patients and 17% for the comparison group. The types of CHADx experienced by diabetes patients with EOS were similar to the comparison group. However, rates were 10 times higher. Linear regression demonstrated diabetes patients with EOS have increased LOS and each CHADx per episode has a larger effect on LOS.

CONCLUSION

We demonstrate that diabetes patients have consistently higher rates of CHADx and longer LOS than similar patients with complex and chronic conditions. This provides a foundation for future studies to investigate preventative practices for this high-risk patient population.

The Goals of Patient Care project: implementing a proactive approach to patient-centred decision-making

BACKGROUND

Patients in the later stages of their lives risk being harmed by futile or unwanted interventions if realistic care goals and patient values are not recognised. Doctors have difficulty discussing and informing patients' healthcare goals.

AIMS

To review implementation of a Goals of Patient Care (GOPC) summary in medical inpatients and its applicability in emergency medical response (EMR) situations.

METHODS

Single-centre cross-sectional study of adult medical inpatients and adult inpatients requiring EMR at a Victorian general hospital.

MEASURES

presence and content of GOPC summary, secondary review of decision-making and discussion documentation, patient characteristics; EMR precipitants and outcomes.

RESULTS

GOPC were documented for 82 of 101 patients. One had an existing advance directive, and six had records of a patient-appointed substitute decision-maker. For patients with GOPC, 80 had life-prolonging treatment aims, with a varying degree of treatment limitation in 48. Discussion with patient or substitute decision-maker was evident in 43 cases. GOPC were documented prior to nine of 23 EMR. The EMR triggered a GOPC modification in three instances.

CONCLUSIONS

Introduction of a routine GOPC summary encourages consideration of goals of care for most medical inpatients. Few have pre-existing records of their wishes, and there are opportunities for improvement in this regard. Doctors may still have difficulty determining goals of care, and discussion of GOPC with patients and families may not be clearly documented. Most patients requiring EMR do not have prior GOPC review, and the role of the summary in these situations remains unclear.

A longitudinal cohort study evaluating the impact of a geriatrician-led residential care outreach service on acute healthcare utilisation

BACKGROUND

over the last decade, high demand for acute healthcare services by long-term residents of residential care facilities (RCFs) has stimulated interest in exploring alternative models of care. The Residential Care Intervention Program in the Elderly (RECIPE) service provides expert outreach services to RCFs residents, interventions include comprehensive care planning, management of inter-current illness and rapid access to acute care substitution services.

OBJECTIVE

to evaluate whether the RECIPE service decreased acute healthcare utilisation.

DESIGN

a retrospective cohort study using interrupted time series analysis to analyse change in acute healthcare utilisation before and after enrolment.

SETTING

a 300-bed metropolitan teaching hospital in Australia and 73 RCFs within its catchment.

SUBJECTS

there were 1,327 patients enrolled in the service with a median age of 84 years; 61% were female.

METHODS

data were collected prospectively on all enrolled patients from 2004 to 2011 and linked to the acute health service administrative data set. Primary outcomes change in admission rates, length of stay and bed days per quarter.

RESULTS

in the 2 years prior to enrolment, the mean number of acute care admissions per patient per year was 3.03 (SD 2.9) versus post 2.4 (SD 3.3), the service reducing admissions by 0.13 admissions per patient per quarter (P = 0.046). Prior to enrolment, the mean length of stay was 8.6 (SD 11.0) versus post 3.5 (SD 5.0), a reduction of 1.5 days per patient per quarter (P = 0.003).

CONCLUSIONS

this study suggests that an outreach service comprising a geriatrician-led multidisciplinary team can reduce acute hospital utilisation rates.

Characteristics of Cytomegalovirus Uveitis in Immunocompetent Patients

PURPOSE

To present the clinical characteristics of patients with anterior uveitis who had evidence of cytomegalovirus (CMV) infection on polymerase chain reaction PCR-based assays for viral DNA in aqueous samples.

METHODS

This was a retrospective observational case series of 16 patients with CMV infection on qualitative polymerase chain reaction PCR-based assays for viral DNA in aqueous samples. Case records of 16 patients were reviewed and relevant clinical information was collected using a standardized data sheet.

RESULTS

There were 10 male and 6 female patients, with 16 eyes included. The median age at the first attack was 52 years (range 27-77 years). Thirteen patients (81.3%) presented with an initial BCVA of 20/40 or better. Eleven eyes (68.8%) had anterior chamber inflammation of 1+ cells or less. Eight eyes (50.0%) had concomitant sectoral iris atrophy, while 2 eyes were noted to have heterochromic irides. Eleven patients (68.8%) presented with an elevated intraocular pressure. Seven patients (43.8%) had clinical features that led to a presumptive diagnosis of Posner-Schlossman syndrome, while 3 patients (18.8%) were initially diagnosed with Fuchs heterochromic iridocyclitis. Six patients were initially treated for uveitic glaucoma or anterior uveitis of unknown cause.

CONCLUSIONS

There is a spectrum of clinical manifestations of CMV anterior uveitis. A high index of suspicion of a possible viral etiology, especially CMV, and subsequent accurate identification of the virus involved are fundamental to the overall therapeutic approach.

Emergency stenting of vertical vein in a neonate with obstructed supracardiac total anomalous pulmonary venous drainage

A late preterm newborn baby presented with respiratory distress and increasing cyanosis within 2 hours of birth. Bedside transthroracic echocardiography showed a critically obstructed vertical vein in a supracardiac total anomalous pulmonary venous drainage (TAPVd). Emergency stenting of the vertical vein was successfully performed at 24 hours of life.

Trends in patterns of intermediate uveitis in a tertiary institution in Singapore

Purpose

The study aims to describe the characteristics and etiologic causes of intermediate uveitis (IU) patients seen by a tertiary eye center in Singapore over 8 years.

Methods

This was a retrospective analysis of the clinical records of consecutive new cases of IU that presented to the uveitis subspecialty clinic from 2004–2011 at Tan Tock Seng Hospital. Data collected included demographics, clinical and laboratory findings. Diagnoses were based on standardized clinical history, ophthalmological examination and investigations.

Results

There were 66 new cases of IU, comprising 5.7% of 1168 new uveitis patients. The median age of diagnosis was 40 years (mean 39.4±15.9), with largest subgroup of the patients in the age group of 41–60 years (36.4%). The majority was Chinese (57.6%), followed by Asian Indians (18.2%) and Malays (16.7%). The ethnicity distribution was dissimilar to our ethnic distribution in Singapore (p<0.001) with an increased incidence of IU in the Asian Indian population. Most were idiopathic (59.1%) in etiology, followed by tuberculosis (TB) (15.2%). Ocular complications developed in 21 patients (31.8%), with cystoid macular edema (CME) being the commonest (28.8%). Severe vitritis occurred in 9.1% of patients, and was significantly associated with TB-associated IU (p<0.001). There was a downward trend for the incidence of the proportion of IU patients over the total uveitis patients (p = 0.021), with Spearman’s rho of −0.786.

Conclusions

Despite the downward trend, TB-associated IU was still of higher prevalence compared to less endemic areas, emphasizing the need for increased TB surveillance. A high index of suspicion for TB-associated IU is required in patients with severe vitritis. Comparisons with other countries revealed disparities in the IU etiologies, indicating possible geographical differences. Prevalence of known immune-mediated etiologies of IU is less compared to the western population. Our study also suggests a probable predisposition of the Singapore local Indian population for IU.

Performance of new signal-to-noise ratio estimation for SEM images based on single image noise cross-correlation

A new technique for estimation of signal-to-noise ratio in scanning electron microscope images is reported. The method is based on the image noise cross-correlation estimation model recently developed. We derive the basic performance limits on a single image signal-to-noise ratio estimation using the Cramer-Rao inequality. The results are compared with those from existing estimation methods including the nearest neighbourhood (the simple method), the first order linear interpolator, and the autoregressive based estimator. The comparisons were made using several tests involving different images within the performance bounds. From the results obtained, the efficiency and accuracy of image noise cross-correlation estimation technique is considerably better than the other three methods.

Impact of troponin 1 on long-term mortality after emergency orthopaedic surgery in older patients

OBJECTIVES

To determine the association between post-operative troponin rises and longer term (2-year) mortality after emergency orthopaedic surgery in patients over 60 years of age.

METHODS

One hundred and two patients were recruited in 2006 and had inpatient troponin 1 measurements. These patients were followed up by a telephone call annually for complications.

RESULTS

At 2 years, 29.4% (30/102) of patients had died. Twenty-five patients (25/54 or 49.3%) with a troponin rise were dead at 2 years compared with five patients without a troponin rise (5/48 or 10.4%), which was significantly different P < 0.0001. Patients with a higher troponin level (>0.1 µg/L) were more likely to be dead at 2 years compared with those with a lower level of troponin. However, when adjusted for other comorbidities the association between troponin elevation and death at 2 years did not persist. Using Cox regression multivariate analysis, only one factor, sustaining an in-hospital cardiac event odds ratio 4.3 (95% confidence interval 1.8-10.3, P = 0.001), was associated with 2 years all-cause mortality . Furthermore, patients who sustained a symptomatic troponin rise (P < 0.0001) or asymptomatic troponin rise (P = 0.004) were more likely to have died at 2 years compared with those with no troponin rise. Three factors were significantly associated with a cardiac event during the second year: (i) post-operative troponin rise (P = 0.05); (ii) pre-morbid atrial fibrillation (P = 0.04); and (iii) post-operative renal failure (P < 0.001).

CONCLUSION

Elevated post-operative troponin levels are predictive of 1-year but not 2-year mortality in older patients undergoing emergency orthopaedic surgery.

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.

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.

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.

G(i) activator region of alpha(2A)-adrenergic receptors: distinct basic residues mediate G(i) versus G(s) activation

The structural determinants of G protein coupling versus activation by G protein-coupled receptors are not well understood. We examine the role of two distinct basic regions in the carboxyl terminal portion of the third intracellular loop of the alpha(2A)-adrenergic receptor to dissect these aspects of function. Changing three arginines to alanines by mutagenesis and stable expression in Chinese hamster ovary-K1 cells impaired the alpha(2)-adrenergic receptor G(s)-mediated stimulation of cyclic AMP (cAMP) accumulation, whereas G(i)-mediated inhibition was normal. When two (B2) or three (B3) basic residues closer to transmembrane span 6 were mutated to alanine, normal ligand binding was observed, but G(i)-mediated inhibition of cAMP accumulation showed 20-fold and 50-fold decreases in agonist potency for the B2 and B3 mutants, respectively. Surprisingly, a normal G(s) response was seen for the B2 mutant, and the B3 mutant showed only a 6-fold decrease in agonist potency. Mutation of both the three alanines and B3 residues to alanines showed a 200-fold decrease in agonist potency for G(i)-mediated inhibition of cAMP accumulation, whereas the G(s) response was nearly completely eliminated. The three basic residues (which include the BB of the BBXXF motif) play a role as G(i) activators rather than in receptor-G protein coupling, because high-affinity agonist binding is intact. Thus, we have identified three basic residues required for activation of G(i) but not required for receptor-G protein coupling. Also, distinct basic residues are required for optimal G(i) and G(s) responses, defining a microspecificity determinant within the carboxyl terminal portion of the third intracellular loop of the alpha(2a) adrenergic receptor.

Effect of hormone replacement therapy on left ventricular hypertrophy

The mechanisms behind the reduction in cardiovascular morbidity and mortality in postmenopausal women receiving hormone replacement therapy are not fully understood. In this case-control study, we report a statistically significant lower left ventricular mass in a group of elderly women who were receiving hormone replacement therapy for >10 years than in age-matched controls.

A prevalence study of chronic rhinitis among residents in Telok Blangah Town, Singapore

A community-based questionnaire survey on a random sample of 562 persons aged seven to 81 years residing in the flatted housing estate of Telok Blangah, Singapore, was studied to determine the prevalence of chronic rhinitis, its associated risk factors and severity of the symptomatology. Chronic rhinitis was defined as the presence of nasal obstruction or clear, watery discharge together with any or both of the following: tearing eyes or sneezing, for a period of more than one month. The overall prevalence was 32.5% with Chinese having the highest ethnic specific rate of 33.9% followed by Indians (27.1%) and Malays (25.4%). The age-specific prevalence rates showed a clear downward trend with increasing age (P < 0.0001). Among the risk factors studied, family history of atopy ranked the highest followed by personal history of atopy and age group (< 30 years and 30 years or more). Most of the chronic rhinitis' symptoms (79%) were graded as not severe.

Thermal stabilities of mutant Escherichia coli tryptophan synthase alpha subunits

Random chemical mutagenesis, in vitro, of the 5' portion of the Escherichia coli trpA gene has yielded 66 mutant alpha subunits containing single amino acid substitutions at 49 different residue sites within the first 121 residues of the protein; this portion of the alpha subunit contains four of the eight alpha helices and three of the eight beta strands in the protein. Sixty-two of the subunits were examined for their heat stabilities by sensitivity to enzymatic inactivation (52 degrees C for 20 min) in crude extracts and by differential scanning calorimetry (DSC) with 29 purified proteins. The enzymatic activities of mutant alpha subunits that contained amino acid substitutions within the alpha and beta secondary structures were more heat labile than the wild-type alpha subunit. Alterations only in three regions, at or immediately C-terminal to the first three beta strands, were stability neutral or stability enhancing with respect to enzymatic inactivation. Enzymatic thermal inactivation appears to be correlated with the relative accessibility of the substituted residues; stability-neutral mutations are found at accessible residual sites, stability-enhancing mutations at buried sites. DSC analyses showed a similar pattern of stabilization/destabilization as indicated by inactivation studies. Tm differences from the wild-type alpha subunit varied +/- 7.6 degrees C. Eighteen mutant proteins containing alterations in helical and sheet structures had Tm's significantly lower (-1.6 to -7.5 degrees C) than the wild-type Tm (59.5 degrees C). In contrast, 6 mutant alpha subunits with alterations in the regions following beta strands 1 and 3 had increased Tm's (+1.4 to +7.6 degrees C). Because of incomplete thermal reversibilities for many of the mutant alpha subunits, most likely due to identifiable aggregated forms in the unfolded state, reliable differences in thermodynamic stability parameters are not possible. The availability of this group of mutant alpha subunits which clearly contain structural alterations should prove useful in defining the roles of certain residues or sequences in the unfolding/folding pathway for this protein when examined by urea/guaninidine denaturation kinetic analysis.

Enzymatic properties of mutant Escherichia coli tryptophan synthase alpha-subunits

Thirty-nine mutant tryptophan synthase alpha subunits have been purified and analyzed (in the presence of the beta 2-subunit) for their enzymatic (kcat, Km) behavior in the reactions catalyzed by the alpha 2.beta 2 complex, the fully constituted form of this enzyme. The mutant alpha subunits, obtained by in vitro random, saturation mutagenesis of the encoding trpA gene, contain single amino acid substitutions at sites within the first 121 residues of the alpha polypeptide. Four categories of altered residues have been tentatively assigned roles in the catalytic functions of this enzyme: 1) catalytic residues (Glu49 and Asp60); 2) residues involved in substrate binding or orientation (Phe22, Thr63, Gln65, Tyr102, and Leu105); 3) residues involved in alpha.beta subunit interactions (Gly51, Pro53, Asp56, Asp60, Pro62, Ala67, Phe72, Thr77, Pro78, Tyr102, Asn104, Leu105, and Asn108); and 4) residues with no apparent catalytic roles. Catalytic residue alterations result in no detectable activity in the alpha-subunit specific reactions. Substrate binding/orientation roles are detected enzymatically primarily as rate defects; alterations only at Tyr102 result in apparent Km effects. alpha.beta interaction roles are detected as rate defects in all tryptophan synthase reactions plus Km increases for the alpha-subunit substrate, indole-3-glycerol phosphate, only when L-serine is present at the beta 2-subunit active site. A substitution at only one site, Asn104, appears to be unique in its potential effect on intersubunit channeling of indole, the product of the alpha-subunit specific reaction, to the beta 2-subunit active site.

Solubilization and renaturation of overexpressed aggregates of mutant tryptophan synthase alpha-subunits

Certain Escherichia coli tryptophan synthase mutant alpha-subunits encoded from mutagenized trpA-containing plasmids were overexpressed as insoluble aggregates which were seen as large, intracellular inclusion bodies. The insoluble aggregates were solubilized to various degrees by several neutral, chaotropic salts. The order of effectiveness of these salts (KSCN, NaI greater than NaNO3, LiBr greater than CaCl2) followed that for the Hofmeister series. Optimum conditions for the use of KSCN resulted in a maximum 70 to 75% solubilization of the aggregate forms for all mutant alpha-subunits examined. Removal of KSCN by dialysis resulted in the recovery of biological activity and of certain characteristic structural properties. Such salts may be a useful alternative for other recombinant protein aggregates which resist complete renaturation by commonly used treatments with guanidine or urea.