Safety and efficacy of cerebral embolic protection devices in transcatheter aortic valve implantation: a meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Stroke during Transcatheter Aortic Valve implantation (TAVI) is not an uncommon complication with potential devastating consequences. With the extension of TAVI to the low-risk patient, stroke prevention takes on increasing importance. The use of cerebral embolic protection device (EPD) reveals conflicting data. This meta-analysis aims to evaluate the clinical efficacy and safety of EPDs.

Methods

A comprehensive literature search for all studies till May 2022 reporting clinical safety and efficacy outcomes of the only EPD approved for use by the Food and Drug Administration (FDA) was performed. Study outcomes were divided based on time period - overall (up to 30 days and in-hospital) and short (≤7 days). Primary outcome was stroke - major and minor. Secondary outcomes included transient ischaemic attack (TIA), mortality, acute kidney injury (AKI), major vascular and bleeding complications.

Results

A total of 12 studies involving 288531 patients were analysed, which included 3 randomised controlled trials (RCTs), 7 propensity-matched and 2 cohort studies. Regarding overall outcomes, significant differences were noted for mortality (OR 0.59 [0.42-0.84], p=0.0036) and major stroke (OR 0.40 [0.18-0.91], p=0.028) (Fig 1). No significant differences were noted for all stroke (p=0.058), minor stroke (p=0.32), TIA (p=0.49), AKI (p=0.17), major vascular complications (p=0.40) and major bleeding complications (p=0.11). There was significant heterogeneity across the studies for mortality (p=0.032) and all stroke (p=0.009). In the subgroup analysis of studies reporting ≤7 days outcomes (n=5), EPDs showed significantly lower rates of all stroke (0.33 [95% CI 0.19-0.56], p=<0.0001), major stroke (0.19 [0.08-0.48], p=0.0004) and major bleeding complications (OR 0.29 [0.10-0.79], p=0.016), but no significant differences for mortality (p=0.67) and minor stroke (p=0.070). There was no significant heterogeneity across the studies (all p>0.05)

Conclusions

In this meta-analysis including non-randomised studies, the use of EPDs was associated with lower mortality and major stroke rates, although significant heterogeneity was noted for the studies reporting mortality. Further ongoing larger scale RCTs will further clarify these results.

Real-world outcomes of Selexipag for treatment of pulmonary hypertension in an Asian population

Funding Acknowledgements

Type of funding sources: None.

Introduction

Selexipag is an oral selective prostacyclin IP receptor agonist indicated for treatment of pulmonary arterial hypertension (PAH). Data on its real-world safety and efficacy in Asians is lacking.

Purpose

We sought to evaluate the clinical characteristics, treatment regimens and outcomes of patients initiated on selexipag in a tertiary cardiac centre in Asia.

Methods

This was a retrospective study on all patients initiated on selexipag from January 2017 to December 2020. Baseline and follow up characteristics including demographics, functional status and clinical data were collected. Clinical outcomes evaluated included hospitalisation for PH related complications and all-cause mortality. Patients were risk stratified using the COMPERA 2.0 risk scores.

Results

A total of 36 PAH patients were treated with selexipag. At baseline, most patients were WHO functional class II or III (36.4% and 51.5% respectively), with a NT-proBNP of 1335 pg/ml (557 – 2918) and 6 minute walk test (6MWT) duration of 327.5 ±126.4 meters. Selexipag was initiated at 200mcg twice daily dosage for all except one patient (started at 200mcg once daily) and the maximum tolerated dose ranged from 200mcg twice daily to 1400mcg twice daily, with majority tolerating up to a dose of 600mcg twice daily (58.3%). Side effects were reported in 23 patients (63.9%), of which headache (27.8%), diarrhea (30.6%) or musculoskeletal symptoms (27.8%) were predominant. After a median follow up duration of 25.9 ± 23.1 months, selexipag was stopped in 20 patients (55.6%), of which eight patients were due to PAH progression requiring alternative therapy, and 12 patients due to side effects from selexipag. At baseline, patients were classified into low (8.3%), intermediate-low (30.6%), intermediate-high (33.3%) and high risk (27.8%) respectively. Patients who continued on selexipag at follow up showed no change (46.2%), improvement (15.4%) and deterioration (38.5%) in risk score. In the overall cohort of 36 patients, majority (75%) had at least one hospitalisation for PAH related complications and 15 patients (41.7%) demised.

Conclusion

In this real-world study, while selexipag was associated with a stable or improved PAH risk scores in majority of patients, there was a subset of patients with disease progression or intolerance to the medication. Further studies are warranted to identify patients who will benefit most from this therapy.

600 Acute Appendicitis as an Early Manifestation of Colorectal Cancer for Patients Aged 40 Years and Above

Aim

Presence of underlying colorectal cancer with acute appendicitis is not unfamiliar in medical literature. However, there remains no clear guidance in the follow-up care post-appendicectomy. This study aims to investigate whether acute appendicitis can be an early manifestation of colorectal cancer in older adults and determine the need of routine pre-operative CT imaging and post-operative colonoscopy as a follow-up screen for early detection of colorectal cancer.

Method

This is a retrospective study comprising 1236 patients, aged 40 years and above, who underwent appendicectomy between January 2006 to September 2021. Results of radiological investigation pre-appendicectomy and colonoscopy post-appendicectomy were reviewed. Patients who were diagnosed immediately and subsequently following appendicectomy were recorded and analysed.

Results

Of the 1236 patients underwent appendicectomy, 636 (51.5%) were male and 600 (48.5%) were female (Median age 53 years; range 40–96 years). Out of 412 (33.3%) patients who had CT imaging, only one revealed sigmoid tumour which was later confirmed as moderately differentiated adenocarcinoma. 71 (5.7%) patients had colonoscopy post-appendicectomy. Among these, two were diagnosed with caecal cancer. A total of 22 (1.8%) patients were diagnosed with colorectal cancer: 13 adenocarcinoma, 5 carcinoid tumours, 3 low-grade mucinous carcinoma peritonei and 1 lymphoma. 15 (1.2%) were diagnosed at the time of appendicectomy, whereas the remaining 7 (0.6%) were diagnosed between 6 months to 11 years post-appendicectomy.

Conclusion

Preliminary finding suggests this is an area that warrant further study. Patients aged 40 years and above may benefit from colonoscopy following appendicectomy to exclude the possibility of underlying colorectal cancer.

Intravenous epoprostenol therapy in the treatment of pulmonary arterial hypertension: the Singapore experience

Funding Acknowledgements

Type of funding sources: None.

Background

Pulmonary arterial hypertension (PAH) is a progressive disease with significant morbidity and mortality. While intravenous (IV) Epoprostenol, a prostacyclin analogue, has been shown to improve exercise tolerance, symptoms, hemodynamics and survival, there are challenges with initiation and maintenance of this IV therapy.

Purpose

We aim to describe our local experience of the use of IV Epoprostenol in the treatment of PAH patients in Singapore, highlighting various issues and challenges.

Methods

From 2016, patients at a tertiary cardiac institution diagnosed with Group 1 PAH and remaining in intermediate to high risk class with progressive symptoms (despite being on maximum tolerable doses of PhosphoDiEsterase-5 inhibitors and Endothelin-1 receptor antagonists) were assessed and counselled for initiation of Epoprostenol therapy. With a fixed set of local protocols, comprehensive assessment and support of a multi-disciplinary team including physicians, specialist nurses and pharmacists, suitable patients were started on this treatment.

Results

A total of 12 patients (11 female, mean age 42.8 +/- 11.0 years) were included. The average New York Heart Association class of the patients initiated on Epoprostenol was II-III. The pulmonary artery pressures and pulmonary vascular resistance on right heart catheterization prior to initiation was 52.5 (IQR 47.0-54.0) mmHg and 12.6 (IQR 10.0-14.2) Woods respectively. The duration from diagnosis to time of initiating Epoprostenol was 89 (IQR 62-140) months. Epoprostenol was generally well tolerated. The most common side effect experienced was diarrhea (5/12 patients) followed by headache and musculoskeletal complains (3/12 patients each). Of the 12 patients, 6 passed away after 12 (IQR 10-16) months of Epoprostenol therapy. Of the remaining 6, PAH was diagnosed 110 (IQR 104-136) months ago and Epoprostenol therapy has been continued for 17 (IQR 14-27) months. Of those who survived, right ventricle size and PA pressures on echocardiography remained relatively stable as compared to those who passed on. 2 patients had line related infections requiring a line change 1 and 2 times respectively.

Conclusion

While not without its challenges, the establishment of concrete protocols with the support of a multidisciplinary team allows for the introduction of IV Epoprostenol as an additional potential line of effective therapy for PAH patients in Singapore.

Risk stratification and prognosis in pulmonary arterial hypertension: the Singapore experience

Funding Acknowledgements

Type of funding sources: None.

Aims & Background: Guidelines recommend the risk stratification of patients with pulmonary arterial hypertension (PAH) at baseline and on follow-up, so as to guide the management and titration of therapy in these patients.  This approach has been validated in various pulmonary hypertension registries in the West.  We aim to study the value of risk stratification on the prognosis of PAH patients in Asia.

Methods

A retrospective review of all PAH patients from 2002 to 2018 from a single tertiary cardiac centre was performed. Inclusion criteria was the availability of both initial visit and follow-up data. Patients were classified into low-, medium-, and high-risk groups in both initial and follow-up visits based on the variables in the 2015 ESC/ERS PH risk stratification table  according to the "score and average" method used by SPAHR and COMPERA registries (total score divided by number of variables assessed and rounded to nearest integer). An average score of 1, 2 and 3 was defined as low, medium and high risk respectively. The primary outcomes was all-cause mortality.

Results

 A total of 102 patients (mean age 57 ± 18 years old, 82 females) were included. Survival was significantly affected by PAH subtype and risk profile. On multivariate analysis, baseline risk did not impact on mortality. Follow-up risk stage impacted on prognosis, with significantly poorer prognosis noted in both intermediate- (adj HR 3.12, 95% CI 1.03 – 9.48, p = 0.045) and high-risk (adj HR = 7.84, 95% CI 2.22 – 27.64, p = 0.001) groups. Patients who improved their risk groups to low risk on follow-up had  similar survival to stable low-risk patients, but those patients whose risk group worsened on follow-up had significantly worse prognosis (adj HR = 5.44, 95% CI 1.26 – 13.75, p = 0.02).

Conclusion

Risk stratification is useful in prognosticating Asian PAH patients. There is potential survival benefit in optimising treatment to achieve a low-risk profile.

Profile of reticulated platelets in the early, subacute and late phases after transient ischemic attack or ischemic stroke

Information regarding the profile of reticulated platelets (RP) in ischemic cerebrovascular disease (CVD) patients is limited. Data from two prospective, observational, case-control studies were combined to compare the %RP using whole blood flow cytometry in patients ≤ 4 weeks of TIA/stroke onset (baseline, N = 210), and 14 ±7 days (14d, N = 182) and ≥ 90 days (90d, N = 145) after starting or changing antiplatelet therapy with healthy controls (N = 34). There were no differences in median %RP between the overall CVD patient population at baseline or 14d vs. controls (P ≥ 0.2). However, the median %RP was significantly higher in CVD patients overall at 90d (P = .036), and in the subgroup of patients with "lacunar" TIA/ischemic stroke at baseline (P = .04) and at 90d (P = .01), but not at 14d (P = .06) vs. controls. There were no significant differences in the median %RP between other TIA/stroke subgroups and controls (P ≥ 0.05). Elevated circulating reticulated platelets, as a marker of increased platelet production/turnover, may occur following an ischemic event in a well-phenotyped TIA/ischemic stroke population overall, but may precede symptom onset at least in the subgroup with small vessel occlusion. These data improve our understanding of the profile of reticulated platelets in CVD patients.

Relationship between 'on-treatment platelet reactivity', shear stress, and micro-embolic signals in asymptomatic and symptomatic carotid stenosis

BACKGROUND

Assessment of 'high on-treatment platelet reactivity (HTPR)' could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy.

METHODS

This prospective, multi-centre study assessed antiplatelet-HTPR status and its relationship with micro-emboli signals (MES) in asymptomatic vs. symptomatic ≥ 50-99% carotid stenosis. Platelet function/reactivity was assessed under 'moderately high shear stress' with the PFA-100^® and 'low shear stress' with VerifyNow^® and Multiplate^® analysers. Bilateral 1-h transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES + ve or MES - ve.

RESULTS

Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the 'early phase' (≤ 4 weeks) and 37 patients in the 'late phase' (≥ 3 months) after TIA/ischaemic stroke. Median daily aspirin doses were higher in early symptomatic (225 mg; P < 0.001), but not late symptomatic (75 mg; P = 0.62) vs. asymptomatic patients (75 mg). There was a lower prevalence of aspirin-HTPR in early (28.6%; P = 0.028), but not late symptomatic (38.9%; P = 0.22) compared with asymptomatic patients (56.7%) on the PFA-100^®, but not on the VerifyNow^® or Multiplate^® (P ≤ 0.53). Early symptomatic patients had a higher prevalence of aspirin-HTPR on the PFA-100^® (28.6%) vs. VerifyNow^® (9.5%; P = 0.049), but not Multiplate^® assays (11.9%, P = 0.10). There was no difference in aspirin-HTPR prevalence between any symptomatic vs. asymptomatic MES + ve or MES - ve subgroup.

DISCUSSION

Recently symptomatic moderate-severe carotid stenosis patients had a lower prevalence of aspirin-HTPR than their asymptomatic counterparts on the PFA-100^®, likely related to higher aspirin doses. The prevalence of antiplatelet-HTPR was positively influenced by higher shear stress levels, but not MES status.

Paediatric cataract surgery in Hospital Kuala Lumpur - A 5-year review of visual outcomes

INTRODUCTION

Paediatric cataract surgery is challenging with reported post-operative visual acuity (VA) of 0.3LogMar or better varying between 33% to 68% of patients.

OBJECTIVE

The aim is to document the post-operative refraction, VA and complications of non-traumatic pediatric cataract surgery performed in a tertiary referral center in Malaysia.

METHODOLOGY

This retrospective study reviewed case notes of all consecutive patients aged 12 years and below who underwent cataract surgery from January 2010 to December 2015. Patients were recruited if they had a minimum of six months post-operative follow-up. Exclusion criteria included traumatic cataract, central nervous system abnormalities, incomplete medical records or pre-existing ocular pathology. Subjects were divided into two groups based on refraction at one month. Subjects with refraction within 1- dioptre of the targeted spherical equivalent were in the success group and the rest were in the failure group.

RESULTS

A total of 111 subjects were recruited (65 subjects in success group and 46 subjects in the failure group). Mean age at surgery was 33.14 (SD: 33.47) months. The success group had significantly longer axial length (p:0.0045, CI: 0.566-0.994, OR: 0.750). At final review, 44.1%(49/111) subjects had visual acuity of 0.3LogMar or better. The success group had better final mean VA in comparison to the failure group (p:0.034, CI:1.079-7.224, OR: 2.791).

CONCLUSION

The outcome of non-traumatic paediatric cataract surgery was acceptable with 58.6% achieved targeted refractive correction at 1-month post-operative period. Longer axial length was associated with better refractive outcome. Capsule related complications was the most common intra-operative complication.

Beyond first-line non-anthracycline-based chemotherapy for extranodal NK/T-cell lymphoma: clinical outcome and current perspectives on salvage therapy for patients after first relapse and progression of disease

Background

Current standard treatment, including non-anthracycline-based chemotherapy and optimal combining of radiotherapy, has dramatically improved outcomes of patients with extranodal natural killer/T-cell lymphoma (ENKTL) during the last decade. This study was conducted to investigate the clinical outcome of ENKTL patients with relapsed or progressive disease after initial current standard therapy.

Patients and methods

We retrospectively reviewed patients diagnosed with ENKTL at six centers in four countries (China, France, Singapore, and South Korea) from 1997 to 2015 and analyzed 179 patients who had relapsed or progressed after initial current standard therapy.

Results

After a median follow-up of 58.6 months (range 27.9-89.2), the median second progression-free survival (PFS) was 4.1 months [95% confidence interval (CI) 3.04-5.16] and overall survival (OS) was 6.4 months (95% CI 4.36-8.51). Multivariate Cox-regression analysis revealed that elevated lactate dehydrogenase, multiple extranodal sites (≥2), and presence of B symptoms were associated with inferior OS (P < 0.05). OS and PFS were significantly different according to both prognostic index of natural killer lymphoma (PINK) and PINK-E (Epstein-Barr virus) models. Salvage chemotherapy with l-asparaginase (l-Asp)-based regimens showed a significantly better clinical benefit to response rate and PFS, although it did not lead to OS improvement. First use of l-Asp in the salvage setting and l-Asp rechallenge at least 6 months after initial treatment were the best candidates for salvage l-Asp containing chemotherapy.

Conclusions

Most patients with relapsed or refractory ENKTL had poor prognosis with short survival. Further studies are warranted to determine the optimal treatment of patients with relapsed or refractory ENKTL.

Oncogenic activation of JAK3-STAT signaling confers clinical sensitivity to PRN371, a novel selective and potent JAK3 inhibitor, in natural killer/T-cell lymphoma

Aberrant activation of the JAK3-STAT signaling pathway is a characteristic feature of many hematological malignancies. In particular, hyperactivity of this cascade has been observed in natural killer/T-cell lymphoma (NKTL) cases. Although the first-in-class JAK3 inhibitor tofacitinib blocks JAK3 activity in NKTL both in vitro and in vivo, its clinical utilization in cancer therapy has been limited by the pan-JAK inhibition activity. To improve the therapeutic efficacy of JAK3 inhibition in NKTL, we have developed a highly selective and durable JAK3 inhibitor PRN371 that potently inhibits JAK3 activity over the other JAK family members JAK1, JAK2, and TYK2. PRN371 effectively suppresses NKTL cell proliferation and induces apoptosis through abrogation of the JAK3-STAT signaling. Moreover, the activity of PRN371 has a more durable inhibition on JAK3 compared to tofacitinib in vitro, leading to significant tumor growth inhibition in a NKTL xenograft model harboring JAK3 activating mutation. These findings provide a novel therapeutic approach for the treatment of NKTL.

Stenosis detection and quantification on cardiac CTCA using panoramic MIP of coronary arteries

In this work, we proposed to demonstrate the entire 3D coronary tree using panoramic maximum intensity projection (MIP) of coronary arteries, and to detect and quantify coronary stenosis from computed tomography coronary angiography (CTCA). The performance of the proposed method was assessed in comparison with invasive coronary angiography (ICA) as reference standard. Six anonymized CTCA datasets were tested. MIP method achieved a sensitivity of 82% and a specificity of 95% for the stenosis detection with a good reproducibility (i.e. Cohen's kappa coefficient of 0.74 for the intra-rater agreement, and 0.45 for the inter-raters agreement). In stenosis quantification, three image options are provided. The original density images resulted in an accuracy of 0.85. The edge map images resulted in an accuracy of 0.79. The image combination had a better accuracy of 0.89 than any single image option. In conclusion, the panoramic MIP provided fast and accurate way for the stenosis detection and quantification. It may be helpful to assist the radiologist in identifying the location of the greatest narrowing in clinical practice.

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.

Do We Have the Right Prognostic Index for Diffuse Large B Cell Lymphoma (DLBCL) in the Era of Rituximab?

Introduction:

Whilst the addition of rituximab, a humanized monoclonal antibody to standard CHOP chemotherapy (R-CHOP) has improved the outcomes of DLBCL, the validity of the previously identified prognostic index based on clinical parameters is questioned. It is conceivable that prognostic model may alter with introduction of new therapeutics with differing efficacy and mechanisms of action.

Methods:

We conducted a retrospective analysis comparing the relevance of International Prognostic Index (IPI), Age-adjusted IPI and Revised International Prognostic Index (R-IPI) in 320 consecutive patients with DLBCL from 2003–2008 treated with R-CHOP chemotherapy with curative intent. We evaluated the prognostic factors determinant of survival in our group of patients.

Results:

Patients were followed up for a median of 2.70 years. IPI was only able to stratify patients into 3 main risk groups instead of 4. In addition, among patients <60, aa-IPI no longer seem a robust prognostic model. We showed that R-IPI was able to separate patients into 3 different prognostic groups and perhaps most relevant in the era of chemo-immunotherapy. Significant prognostic factors identified in multivariate analysis were performance status (P=0.004) and bone marrow involvement (P=0.026).

Conclusion:

The most robust prognostic index for patients with DLBCL in the era of rituximab remains uncertain. Incorporation of molecular markers into clinical parameters should be evaluated, a study we are embarking on.

Central nervous system (CNS) relapse in diffuse large B cell lymphoma (DLBCL): pre- and post-rituximab

Central nervous system (CNS)-directed prophylactic intrathecal (IT) therapy is indicated in patients with Burkitt and acute lymphoblastic lymphoma. Its role in diffuse large B cell lymphoma (DLBCL), a heterogeneous subtype, is less well defined. While addition of rituximab to standard cyclophosphamide-hydroxydaunorubicin-oncovin-prednisone (CHOP) chemotherapy (R-CHOP) has improved the outcomes of DLBCL patients, its role in reducing CNS relapse is unclear. We aim to (1) evaluate the clinical risk factors predictive of CNS relapse, (2) the role of rituximab in influencing CNS relapse, and (3) role of intrathecal prophylaxis. Four hundred ninety-nine patients with DLBCL from 2000 to 2008 were included (CHOP 179 vs. R-CHOP 320). IT prophylaxis was administered to 82 patients based on our institution's guidelines. Baseline characteristics between CHOP- and R-CHOP-treated patients were similar. Although R-CHOP significantly increased the complete remission rate from 71% to 81% (P < 0.01), CNS relapse rates remained unchanged (R-CHOP 6% vs. CHOP 5.1%). On multivariate analysis, poor performance status (Eastern Cooperative Oncology Group >1; hazard ratio (HR) = 2.01, 95% confidence interval (CI) 1.29-3.14), failure to attain remission (non-complete response (CR) vs. CR: HR = 2.39, 95% CI = 1.03 to 5.51), testicular (HR = 6.67, 95% CI = 1.62 to 27.53), kidney (HR = 20.14, 95% CI = 5.23 to 77.46), and breast involvement (HR = 6.14, 95% CI = 1.61 to 23.37) were each independently predictive of CNS relapse. Use of IT prophylaxis did not appear to decrease CNS relapse. Median survival after CNS relapse was 3.2 months. CNS relapse, a fatal event, remains a challenge in R-CHOP-treated patients. IT prophylaxis may not be sufficient to reduce CNS relapse, and strategies including systemic agents with high CNS penetration should be evaluated in high-risk patients identified in this study.

Central nervous system (CNS) relapse in diffuse large B cell lymphoma (DLBCL): pre- and post-rituximab

Central nervous system (CNS)-directed prophylactic intrathecal (IT) therapy is indicated in patients with Burkitt and acute lymphoblastic lymphoma. Its role in diffuse large B cell lymphoma (DLBCL), a heterogeneous subtype, is less well defined. While addition of rituximab to standard cyclophosphamide-hydroxydaunorubicin-oncovin-prednisone (CHOP) chemotherapy (R-CHOP) has improved the outcomes of DLBCL patients, its role in reducing CNS relapse is unclear. We aim to (1) evaluate the clinical risk factors predictive of CNS relapse, (2) the role of rituximab in influencing CNS relapse, and (3) role of intrathecal prophylaxis. Four hundred ninety-nine patients with DLBCL from 2000 to 2008 were included (CHOP 179 vs. R-CHOP 320). IT prophylaxis was administered to 82 patients based on our institution's guidelines. Baseline characteristics between CHOP- and R-CHOP-treated patients were similar. Although R-CHOP significantly increased the complete remission rate from 71% to 81% (P < 0.01), CNS relapse rates remained unchanged (R-CHOP 6% vs. CHOP 5.1%). On multivariate analysis, poor performance status (Eastern Cooperative Oncology Group >1; hazard ratio (HR) = 2.01, 95% confidence interval (CI) 1.29-3.14), failure to attain remission (non-complete response (CR) vs. CR: HR = 2.39, 95% CI = 1.03 to 5.51), testicular (HR = 6.67, 95% CI = 1.62 to 27.53), kidney (HR = 20.14, 95% CI = 5.23 to 77.46), and breast involvement (HR = 6.14, 95% CI = 1.61 to 23.37) were each independently predictive of CNS relapse. Use of IT prophylaxis did not appear to decrease CNS relapse. Median survival after CNS relapse was 3.2 months. CNS relapse, a fatal event, remains a challenge in R-CHOP-treated patients. IT prophylaxis may not be sufficient to reduce CNS relapse, and strategies including systemic agents with high CNS penetration should be evaluated in high-risk patients identified in this study.

Matrix metalloproteinase-dependent shedding of intercellular adhesion molecule-5 occurs with long-term potentiation

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that can be released or activated in a neuronal activity dependent manner. Although pathologically elevated levels of MMPs may be synaptotoxic, physiologically appropriate levels of MMPs may instead enhance synaptic transmission. MMP inhibitors can block long term potentiation (LTP), and at least one family member can affect an increase in the volume of dendritic spines. While the mechanism by which MMPs affect these changes is not completely understood, one possibility is that the cleavage of specific synaptic cell adhesion molecules plays a role. In the present study, we have examined the ability of neuronal activity to stimulate rapid MMP dependent shedding of the intercellular adhesion molecule-5 (ICAM-5), a synaptic adhesion molecule that is thought to inhibit the maturation and enlargement of dendritic spines. Since such cleavage would likely occur within minutes if it were relevant to a process such as LTP, we focused on post stimulus time points of 30 min or less. We show that NMDA can stimulate rapid shedding of ICAM-5 from cortical neurons in dissociated cell cultures and that such shedding is diminished by pretreatment of cultures with inhibitors that target MMP-3 and -9, proteases thought to influence synaptic plasticity. Additional studies suggest that MMP mediated cleavage of ICAM-5 occurs at amino acid 780, so that the major portion of the ectodomain is released. Since reductions in ICAM-5 have been linked to changes in dendritic spine morphology that are associated with LTP, we also examined the possibility that MMP dependent ICAM-5 shedding occurs following high frequency tetanic stimulation of murine hippocampal slices. Results show that the shedding of ICAM-5 occurs in association with LTP, and that both LTP and the associated ICAM-5 shedding are reduced when slices are pretreated with an MMP inhibitor. Together, these findings suggest that neuronal activity is linked to the shedding of a molecule that may inhibit dendritic spine enlargement and that MMPs can affect this change. While further studies will be necessary to determine the extent to which cleavage of ICAM-5 in particular contributes to MMP dependent LTP, our data support an emerging body of literature suggesting that MMPs are critical mediators of synaptic plasticity.

Percutaneous transcatheter aortic valve replacement: first transapical implant in Asia

Percutaneous transcatheter implantation of the aortic valve has been demonstrated as an alternative to open heart surgery in high-risk patients with symptomatic severe aortic stenosis (AS) who are not suitable for open surgery. The majority of these new devices are delivered via the transfemoral approach. However, due to the current size of delivery sheaths, the small and tortuous iliofemoral anatomy makes this approach challenging. The transapical approach provides a viable option for this patient subgroup. The first-in-Asia transcatheter aortic valve implantation via the transapical route is described. A 79-year-old Chinese woman with symptomatic severe AS and peripheral arterial disease, who was at high surgical risk, was successfully treated, and had good functional and haemodynamic results at the three-month follow-up.

High SUV uptake on FDG-PET/CT predicts for an aggressive B-cell lymphoma in a prospective study of primary FDG-PET/CT staging in lymphoma

BACKGROUND

Data assessing the role of positron emission tomography (PET)/computed tomography (CT) imaging in lymphoma staging is still being accumulated and current staging is based primarily on CT. This study aims to compare the value of PET/CT over conventional CT and bone marrow biopsy (BMB) in the initial evaluation of patients with lymphoma.

METHODS

Data on 122 patients with PET/CT scans as part of their initial staging were prospectively collected and reviewed. All patients had complete staging, including BMB.

RESULTS

Among the 122 patients, 101 had non-Hodgkin's lymphoma (NHL) and 21 had Hodgkin's lymphoma (HL). Compared with conventional CT, PET/CT upstaged 21 (17%) cases [B-cell non-Hodgkin's lymphoma (B-NHL), 12; T-cell non-Hodgkin's lymphoma (T-NHL), 3; HL, 6]. Of significance, in 13 patients with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG)-avid splenic lesions, four had normal CT findings. A maximum FDG uptake of >10 standardized uptake value (SUV) seems to significantly correlate with an aggressive B-cell lineage (odds ratio 2.47, 95% confidence interval 2.23-2.70). Overall, PET scan was concordant with BMB results in 108 (89%) and discordant in 14 (11%) cases. In HL, our data show that PET scan and marrow results agreed in 19 of the cases (90%), being concordantly negative in 18 cases and concordantly positive in one, giving a negative predictive value (NPV) of 100%, sensitivity of 100% and specificity of 90%. Of note, all 13 with early-stage HL had negative PET/CT scan and BMB. In NHL, all 17 cases of T-NHL had concordant PET and BMB results. In patients with aggressive B-NHL, BMB and PET/CT agreed in 58 patients (92%) and disagreed in five (8%), while the corresponding rates in indolent B-cell lymphoma were 14 (67%) and seven patients (33%), respectively. All seven were falsely negative.

CONCLUSIONS

PET/CT upstages 17% of cases and detects occult splenic involvement. This may have potential therapeutic and prognostic implications. SUV >10 may predict for an aggressive histology. Except for indolent B-NHL, our data show that PET scans have a good overall NPV in excluding lymphomatous bone marrow involvement. This is particularly true of early-stage HL, suggesting that BMB may be safely omitted in this group.

Analysis of long-term treatment outcomes and toxicty of HL

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Background: Prognosis of patients with Hodgkin lymphoma (HL) has substantially improved but therapy of HL can however contribute to delayed toxicity. Long term treatment outcomes of HL in our local population were evaluated. Methods: Clinical and treatment data was prospectively collected from all patients with a histological diagnosis of HL. Patients were all fully staged with CT scan and bone marrow biopsy. Results: On the basis of 217 patients seen at the National Cancer Centre Singapore between 1990–2008, we found that there was a peak in young adulthood with 103 patients who were diagnosed before the age of 30 (48%), median age of presentation 32 (range 17–84). Patients who were young (< 30 years) were more likely to present with nodular sclerosis HL (p=0.0001). Treatment outcomes were comparable to other published series, 85% of cases received ABVD based treatment. 5 year OS for early stage HL was 92% and 88% for advanced stage HL. Overall FFTF was 93% at 5 years. Of note, comparing patients with early stage (Stage I/ II) HL (n=114) who had ABVD 4 cycles followed by involved field radiotherapy (IFRT) with those who received 6–8 cycles of ABVD, there was no difference in OS, FFTF (p= 0.99, 0.48 respectively). Bulky early stage HL who received 6 cycles of ABVD and IFRT had better FFTF rates than those who had just 4 cycles of ABVD followed by IFRT (p=0.06). In contrast, patients patients with advanced HL (Stage III/ IV) (n=70) who completed 6–8 cycles of ABVD did not benefit from additional IFRT even in the presence of bulky disease (n=15). Acute toxicities included that of bleomycin induced pneumonitis (BIP) seen in 15% of cases. Neither the omission of bleomycin nor the presence BIP adversely affected treatment outcomes. Hematological malignancies were seen in 1% of survivors appearing after a median of 7.3 years. Hypothyroidism was noted in 3% of cases. Conclusions: 1) Epidemiology of HL in Singapore is increasingly similar to that of developed countries with a peak in young adults. 2)Young age was predictive of a nodular sclerosis subtype 3) Abbreviated chemotherapy using 4 cycles of ABVD followed by IFRT performed similarly to 6 cycles of ABVD in early stage HL, but in patients with bulky disease this may not be sufficient. 4) BIP occurred in 15% of cases. BIP and the omission of bleomycin did not adversely affect treatment outcomes.

No significant financial relationships to disclose.

Percutaneous transcatheter aortic valve replacement: first transfemoral implant in Asia

Surgical aortic valve replacement (AVR) is the standard of care for patients with symptomatic severe aortic stenosis (AS), providing relief of symptoms and prolonging survival. However, many patients are either denied or not offered surgery due to high surgical risk or non-operability for open AVR. The technology of percutaneous aortic valve implantation emerged in 2002, and has since evolved rapidly with satisfactory results. Currently, almost all the procedures are performed predominantly in Europe and North America. The first-in-Asia percutaneous transcatheter aortic valve implantation via the transfemoral route is described. A 77-year-old man with symptomatic severe AS and at high surgical risk was successfully treated, with sustained clinical improvement and satisfactory haemodynamic results at 30-day follow-up.

Lipid-altering efficacy of ezetimibe/simvastatin 10/40 mg compared with doubling the statin dose in patients admitted to the hospital for a recent coronary event: the INFORCE study

BACKGROUND

The aim of this study was to investigate the efficacy and safety profile of switching to ezetimibe/simvastatin (Eze/Simva) 10/40 mg compared with doubling the statin dose upon discharge in patients taking a statin and admitted to the hospital for the investigation of a coronary event.

DESIGN

This phase IV, multi-centre, randomised, open-label, active-controlled, parallel group study enrolled 424 patients (aged >/= 18 years) hospitalised for an acute coronary event and taking a stable dose of a statin (>/= 6 weeks) that could be doubled per the product label. Upon discharge from the hospital, patients were stratified by their statin dose/potency (high, medium and low) and randomised 1 : 1 to doubling of the statin dose (n = 211) or Eze/Simva 10/40 mg (n = 213) for 12 weeks. The primary efficacy variable was the absolute low-density lipoprotein cholesterol (LDL-C) value (mmol/l) at study end-point.

RESULTS

Mean baseline LDL-C for the two treatment groups were 2.48 and 2.31 mmol/l for the Eze/Simva and statin groups respectively. At study end-point, least squares mean LDL-C values were 1.74 mmol/l in the Eze/Simva group and 2.22 mmol/l in the statin group resulting in a significant between-group difference of -0.49 mmol/l (p </= 0.001). Eze/Simva 10/40 mg also produced significantly lower total cholesterol (-0.49 mmol/l), non-high-density lipoprotein cholesterol [(non-HDL-C); -0.53 mmol/l] and apolipoprotein B (-0.14 mmol/l) values compared with doubling the statin dose (p </= 0.001 for all). Both treatments produced similar effects on triglycerides, C-reactive protein and HDL-C; the between treatment group differences were not significant (p >/= 0.160). Significantly more patients achieved LDL-C levels < 2.5 (< 100 mg/dl; 86% vs. 72%), < 2.0 (< 77 mg/dl; 70% vs. 42%) and < 1.8 mmol/l (< 70 mg/dl; 60% vs. 31%) with Eze/Simva than statin (all p </= 0.001). Eze/Simva was generally well tolerated, with a safety profile similar to statin. There were no differences in the incidences of liver transaminases >/= 3 x upper limit of normal (ULN) or creatine kinase >/= 10 x ULN between the groups.

CONCLUSIONS

In patients taking a statin and admitted to the hospital for investigation of a coronary event, treatment with Eze/Simva 10/40 mg for 12 weeks produced greater improvements in lipids with a similar safety profile compared with doubling of the statin dose.

Clinical features and outcome of emergency percutaneous intervention of left main coronary artery occlusion in acute myocardial infarction

INTRODUCTION

Acute myocardial infarction (AMI) due to left main coronary artery (LMCA) occlusion carries a grave prognosis. Large series reporting on the outcome of emergency revascularisation (percutaneous or surgical) of acute LMCA occlusion have been scarce. We seek to identify, in our local population, the clinical presentation and outcome of this group of patients.

METHODS

From January 2000 to December 2005, a total of 1,539 patients underwent primary percutaneous coronary angioplasty for AMI in our institution. 11 patients (0.8 percent) underwent percutaneous intervention to the LMCA. These patients became the subjects of our study. Data on demography, clinical features and outcome was collected from all in-hospital and clinical notes. One sub-investigator, who was blinded to the study outcome, assessed the angiographical features.

RESULTS

The overall inpatient mortality was 82 percent (9 out of 11). Nine out of 11 patients presented with cardiogenic shock. All patients presented with shock died during the hospital stay. All patients required intra-aortic balloon counter pulsation insertion. Of the two patients who survived till discharge, one had angioplasty followed by bypass surgery. The remaining one had angioplasty and stenting to the left main artery. Both survivors have been doing well without further major adverse cardiac event after an average of 64 months of follow-up.

CONCLUSION

Percutaneous revascularisation of acute LMCA occlusion is feasible and the best outcome is seen in stable patients. Prognosis is still poor in patients with unfavourable clinical features.

Effect of left ventricular shape alteration on contractility and function

We have investigated the effect of left ventricular (LV) shape on contractility and ejection function. In this study, a new contractility index is developed in terms of the wall stress (sigma*, normalized with respect to LV pressure) by means of an LV ellipsoidal model. Using cine-ventriculography data, the LV ellipsoidal model (LVEM) major (B) and minor axes (A) are derived for the entire cardiac cycle. Thereafter, a new contractility index (CONT1) is derived as dsigma*/dt, incorporating the LV ellipsoidal shape factor. Also, another contractility index (CONT2) was developed in terms of the generated sigma* at the start of ejection phase, and maximized with respect to B/Ashape parameter, to obtain the optimal value of B/Aover the physiological ranges of the ratio of myocardial volume and LV volume. The in vivovalue of B/Aat the start of ejection is compared with this optimal value, and the LV contractility is evaluated in terms of the proximity of the in vivo B/Ato the optimal B/A. The results indicate that a non-optimal less-ellipsoidal shape (or more spherical) is associated with decreased contractility (and poor systolic function) of the LV, associated with a failing heart.

Electrocardiographical case. Beware of this ECG in patients presenting with cardiogenic shock

A 64-year-old Chinese man presented to the Accident and Emergency Department with chest pain and was found to be in cardiogenic shock. The electrocardiogram (ECG) showed features of acute myocardial infarction due to left main coronary artery occlusion,which had no ST elevation in precordial leads. Emergency coronary angiogram revealed left main coronary artery complete occlusion. Percutaneous intervention of the left main coronary artery was carried out. The epidemiology and clinical features of a left main occlusion were briefly described, and ECG features of a left main occlusion were discussed.

Recurrence after Successful Percutaneous Endoscopic Lumbar Discectomy

The purpose of this study is to investigate the risk factors for recurrence after successful percutaneous endoscopic lumbar discectomy (PELD). Recently, PELD has become the most common surgical technique. However, there are only a few studies on the factors causing the reappearance of the symptoms. Between January 2002 and December 2004, 42 patients with recurrent disc herniation after successful PELD were classified as a recurrent group and 42 patients who underwent PELD with a satisfactory result were randomly selected for a non-recurrent group. For all the patients, we analyzed the medical records and radiological studies retrospectively. The patients' mean age was 47.4 years (range: 18-76) in the recurrent group, while the mean age of the non-recurrent group was 34.4 years (range: 17-66) (p=0.001). The body mass index was 24.9 in the recurrent group and 22.9 in the non-recurrent group (p=0.006). On the radiological studies, the protrusion (p=0.013) and the presence of Modic change (p=0.003) were more frequent in the recurrent group. For the successful PELD, it is desirable for the surgeon to consider the above risk factors carefully.

Association analysis of endothelial nitric oxide synthase gene polymorphism with primary hypertension in a Singapore population

Vascular endothelial cells produce nitric oxide (NO), which contributes to the regulation of blood pressure and regional blood flow. Endothelial nitric oxide synthase (eNOS) gene polymorphisms are associated with coronary artery disease, but their linkage with primary hypertension is controversial. A total of 103 individuals with primary hypertension and 104 normotensive control subjects were studied in Singapore. The specific genotypes for G894T missense variant in exon 7, variable number tandem repeats (VNTR) in intron 4 (eNOS 4A/B/C) and T-786C in the promoter were isolated using allele-specific gene amplification and restriction fragment length polymorphism to examine the association of genotype and allelic frequency in both groups. Logistic regression analysis was also used to detect the association between genotypes and hypertension. Five genotypes of intron 4 VNTR (AA, AB, BB, AC and BC) were observed. Intron 4 B/B genotype was significantly associated with the hypertension group (P = 0.035), but disequilibrium of G894T and T-786C was absent between the two groups (P = 0.419 and P = 0.227), respectively. The overall distribution of allelic frequency differed significantly between the two groups, with four-repeat allele (4A) of intron 4 more frequent in the normotensive group than the hypertensive group (P = 0.019). Logistic regression analysis showed that intron 4 B/B genotype was significantly associated with systolic blood pressure of individuals with body mass index greater than 25 kg/m2 (P = 0.04). In conclusion, the eNOS 4 B/B genotype is a genetic susceptibility factor for primary hypertension in a Singapore population.

Inter‐ and intralaboratory variation of in vitro diffusion cell measurements: An international multicenter study using quasi‐standardized methods and materials

In vitro measurements of skin absorption are an increasingly important aspect of regulatory studies, product support claims, and formulation screening. However, such measurements are significantly affected by skin variability. The purpose of this study was to determine inter- and intralaboratory variation in diffusion cell measurements caused by factors other than skin. This was attained through the use of an artificial (silicone rubber) rate-limiting membrane and the provision of materials including a standard penetrant, methyl paraben (MP), and a minimally prescriptive protocol to each of the 18 participating laboratories. "Standardized" calculations of MP flux were determined from the data submitted by each laboratory by applying a predefined mathematical model. This was deemed necessary to eliminate any interlaboratory variation caused by different methods of flux calculations. Average fluxes of MP calculated and reported by each laboratory (60 +/- 27 microg cm(-2) h(-1), n = 25, range 27-101) were in agreement with the standardized calculations of MP flux (60 +/- 21 microg cm(-2) h(-1), range 19-120). The coefficient of variation between laboratories was approximately 35% and was manifest as a fourfold difference between the lowest and highest average flux values and a sixfold difference between the lowest and highest individual flux values. Intralaboratory variation was lower, averaging 10% for five individuals using the same equipment within a single laboratory. Further studies should be performed to clarify the exact components responsible for nonskin-related variability in diffusion cell measurements. It is clear that further developments of in vitro methodologies for measuring skin absorption are required.

Can patients with early-stage diffuse large B-cell lymphoma be treated without bone marrow biopsy?

BACKGROUND

Data on the incidence of bone marrow (BM) involvement in early-stage diffuse large B-cell lymphoma (DLBCL) are lacking. Although BM biopsy is a safe procedure, it is often poorly tolerated. This analysis aims to assess the incidence of BM involvement and to identify parameters predicting BM involvement in early-stage DLBCL.

PATIENTS AND METHODS

One hundred and ninety-two patients with radiological stages 1 and 2 disease were analysed. The data collected were age, sex, presence of B symptoms, white blood cell (WBC) count, platelet count, haemoglobin (Hb), serum lactate dehydrogenase level, serum beta(2)-microglobulin level, presence of extranodal disease, and the presence of bulky disease (defined as >7 cm).

RESULTS

Overall incidence of BM involvement was 3.6%. Hb < 10 g/dl (P=0.02), WBC count < 4 x 10(9)/l (P=0.007) and bulky disease (P=0.06) were found to be predictive of BM involvement. Among the 120 patients without any of these three factors, only one patient had BM involvement (0.83%; 95% confidence interval 0.02% to 4.6%). The absence of all three factors gave a negative predictive value of 99.2%. Overall 3-year survival for patients without all three risk factors was 80%.

CONCLUSIONS

BM biopsy may be safely omitted in selected patients with early-stage DLBCL.

Posterior mediastinal paraganglioma with bilateral adrenal pheochromocytoma

Paraganglioma and adrenal pheochromocytoma are tumors of common origin arising from chromaffin cells. However, it is extremely rare to find mediastinal paraganglioma simultaneously with bilateral adrenal pheochromocytoma. We report a 53-year-old man who was diagnosed with posterior mediastinal paraganglioma and bilateral adrenal pheochromocytoma and who underwent successful excision of the posterior mediastinal mass and bilateral total adrenalectomy.

CPT-11 and cisplatin in the treatment of advanced gastric cancer in Asians

There is no standard chemotherapy for advanced gastric cancer. A combination of CPT-11 and cisplatin was evaluated for response and toxicity in Asians. 38 patients with histologically proven stage IV gastric/gastroesophageal junction adenocarcinoma were treated with CPT-11 50 mg/m2 and cisplatin 30 mg/m2 weekly for 3 weeks. Each cycle was repeated every 28 days. The median number of cycles was 1.66 (range 0.33-4.33). Dose delay was needed in 11 (29%) patients and dose reductions in 19 (50%) patients. The overall response rate was 42%. There was no complete response. Grade 3 and 4 hematological toxicity was 26%. Grade 3 or 4 diarrhea was not common. Median time to progression for all patients was 15 weeks. Median duration of survival of all patients was 42 weeks. Patients with better performance status and no prior chemotherapy did better. CPT-11 and cisplatin is a useful regimen with significant but manageable toxicity that can be administered without a central venous catheter.

Turbulent drag reduction and degradation of DNA

Turbulent drag reduction induced by lambda-DNA is studied. The double-stranded DNA is found to be a good drag reducer when compared with the other normal linear polymers. However, this drag reducing power disappears when the DNA denatures to form two single-strand molecules. Mechanical degradation of DNA is also different from that of the normal linear-chain polymers: DNA is always cut in half by the turbulence. Our results suggest that the mechanism for turbulent degradation of DNA is different from that of the normal flexible long-chain polymers.

Rheumatic heart diseases in pregnancy

Acute rheumatic fever and rheumatic valvular disease remain prevalent in many parts of the world, and are probably the most common cause of heart disease in pregnancy. Mitral stenosis is the most frequently encountered rheumatic valvular lesion. A variety of pregnancy-associated cardiovascular changes often exacerbate the signs and symptoms of valvular lesions. Pregnancy should not be allowed to proceed, if possible, in patients with uncorrected severe valvular lesions or mechanical heart valves requiring anticoagulation, as maternal and fetal morbidity and mortality are high. For those with milder disease, pregnancy is best undertaken after the valvular lesion has been rectified or stabilised. Recent advances in the management of valvular disease include the use of beta-blockers for patients with mitral stenosis, vasodilators in those with aortic and mitral regurgitation, and percutaneous balloon valvuloplasty for mitral and aortic stenosis. Application of these therapies in the pregnant patient is as yet unclear, and management decision needs to be individualized, weighing the risk and benefit to ensure maternal survival and to promote fetal well-being.

Analysis of alkali-soluble glucan produced by Saccharomyces cerevisiae wild-type and mutants

The alkali-soluble glucan of the yeast cell wall contains beta-(1,3)- and (1,6)-D-linkages and systemically enhances the immune system. To isolate Saccharomyces cerevisiae mutants producing glucan with a high degree of beta-(1,6)-D-glycosidic bonds, a wild-type strain was mutagenized with ultraviolet light. The mutants were then selected by treatment with 1.0 mg laminarinase, endo-beta-(1,3)-D-glucanase/ml. The alkali-soluble glucan was extracted by modified alkalysis followed by the Cetavlon method and concanavalin-A chromatography. The prepared alkali-soluble glucans from the wild-type and the mutants were compared with respect to yield and polymer structure using gas chromatography, 13C-NMR spectrometry, high performance liquid, and multi-angle laser light scattering and refractive index detectors. The results indicated that the S. cerevisiae mutants had ten-fold more alkali-soluble glucan than the wild-type. Structural analysis revealed that the alkali-soluble glucan from the mutants also had a higher degree of beta-(1,6)-D-linkage than that from the wild-type.

Dynamic localization and clustering of dendritic Kv2.1 voltage-dependent potassium channels in developing hippocampal neurons

Dendritic excitability is modulated by the highly variable spatial and temporal expression pattern of voltage-dependent potassium channels. Somatodendritic Kv2.1 channels contribute a major component of delayed rectifier potassium current in cultured hippocampal neurons, where Kv2.1 is localized to large clusters on the soma and proximal dendrites. Here we found that dramatic differences exist in the clustering of endogenous Kv2.1 in cultured rat hippocampal GABAergic interneurons and glutamatergic pyramidal neurons. Studies on neurons developing in culture revealed that while a similar sequence of Kv2.1 localization and clustering occurred in both cell types, the process was temporally delayed in pyramidal cells. Localization and clustering of recombinant green fluorescent protein-tagged Kv2.1 occurred by the same sequence of events, and imaging of GFP-Kv2.1 clustering in living neurons revealed dynamic fusion events that underlie cluster formation. Overexpression of GFP-Kv2.1 accelerated the clustering program in pyramidal neurons such that the observed differences in Kv2.1 clustering in pyramidal neurons and interneurons were eliminated. Confocal imaging showed a preferential association of Kv2.1 with the basal membrane in cultured neurons, and electrophysiological recordings from neurons cultured on transistors revealed that Kv2.1 contributed the bulk of a previously described adherens junction delayed rectifier potassium conductance. Finally, Kv2.1 clusters were found spatially associated with ryanodine receptor intracellular Ca(2+) ([Ca(2+)](i)) release channels. These findings reveal a stepwise assembly of Kv2.1 potassium channels into membrane clusters during development, and an association of these clusters with Ca(2+) signaling apparatus. Together these data suggest that the restricted localization of Kv2.1 may play an important role in the previously observed contribution of this potassium channel in regulating dendritic [Ca(2+)](i) transients.

In vivo evaluation of novel hyaluronan/chitosan microparticulate delivery systems for the nasal delivery of gentamicin in rabbits

Biodegradable microparticles containing gentamicin were prepared using chitosan hydroglutamate (CH), hyaluronic acid (HA) and a combination of both polymers by a solvent evaporation method. These formulations were administered nasally via an insufflator. Gentamicin was also administered nasally into rabbits as a solution and powder (a physical mixture of gentamicin and lactose), intravenously (IV) and intramuscularly (IM). The resultant serum levels of gentamicin were determined by Fluorescence Polarisation Immunoassay (FPIA). The bioavailability of gentamicin was poor when administered as a nasal solution (1.1%) and dry powder (2.1%) when compared with IV. However, the microparticulate systems composed of CH and HA/CH considerably enhanced the bioavailability of gentamicin (31.4 and 42.9%, respectively,) with HA microparticles inducing a less significant enhancement (23.3%). Previous in vitro dissolution and frog palate studies indicated that these microparticulate formulations were all mucoadhesive and demonstrated prolonged drug release. Such findings were translated into an increase in the bioavailability of gentamicin when compared with a simple nasal solution in vivo. When HA and CH were combined in the HA/CH formulation, the polymers appeared to improve the absorption of incorporated gentamicin synergistically in comparison to the individual polymers, suggesting a promising nasal delivery system.

Focal pulmonary uptake during Tc-99m myocardial perfusion SPECT imaging

PURPOSE

To evaluate the incidence and origin of abnormal focal pulmonary uptake during myocardial perfusion SPECT imaging (MSPECT).

METHODS

For evaluation of chest pain, 790 men and 581 women (mean age, 56 +/- 13 years) underwent MSPECT. All of them received adenosine for pharmacologic stress and Tc-99m tetrofosmin (TF, n = 817) or Tc-99m sestamibi (MIBI, n = 554) for myocardial perfusion imaging.

RESULTS

Review of chest radiography with or without computed tomography revealed 111 (8.1%) focal pulmonary diseases. Among them, 38 (34.2%) showed focal pulmonary uptake (TF, 22; MIBI, 16); 27 (30.7%) of 88 showed previous pulmonary tuberculosis; 2 of 10 (20%) benign pulmonary nodules; 4 of 5 (80%) metastatic lung cancers; 2 of 4 (50%) primary lung cancers; and 3 of 4 (75%) pneumonias. No difference in uptake was noted for the two imaging agents. Intensity of uptake did not vary with origin of the uptake. Focal abnormal pulmonary uptake was found in 2.8% of patients undergoing MSPECT and in 34.2% of patients in whom radiological examinations showed regional pulmonary disease. In patients with abnormal pulmonary uptake on MSPECT, 16% had a malignant lesion, whereas 75% of patients with a pulmonary nodule shown on radiography and focal pulmonary uptake on MSPECT had a malignant lesion.

CONCLUSIONS

Although the incidence of abnormal pulmonary uptake during MSPECT was very low, the incidence of malignant lesions in the patients with nodular pulmonary uptake was relatively high.