Xerostomia: an update for clinicians

Saliva plays an important protective role in the oral environment, and reductions in saliva quantity are known to increase the risk of oral diseases. Importantly, xerostomia or the perception of a dry mouth is now being recognized as an important risk factor for dental diseases. Furthermore, the subjective sensation of a dry mouth is a debilitating condition in itself that impacts on the quality of life of sufferers. With approximately 1 in 5 people reporting some form of dry mouth, and an increasing prevalence in the elderly, it is important for clinicians to have a thorough understanding of this problem. The aim of this paper is to review some of the literature relating to xerostomia in order to provide an evidence based update for clinicians.

Succinate independently stimulates full platelet activation via cAMP and phosphoinositide 3-kinase-β signaling

BACKGROUND

The citric cycle intermediate succinate has recently been identified as a ligand for the G-protein-coupled receptor (GPCR) SUCNR1. We have previously found that this receptor is one of the most highly expressed GPCRs in human platelets.

OBJECTIVE

The aim of this study was to investigate the role of SUCNR1 in platelet aggregation and to explore the signaling pathways of this receptor in platelets.

METHODS AND RESULTS

Using real-time-PCR, we demonstrated that SUCNR1 is expressed in human platelets at a level corresponding to that of the P2Y(1) receptor. Light transmission aggregation experiments showed dose-dependent aggregation induced by succinate, reaching a maximum response at 0.5 mM. The effect of succinate on platelet aggregation was confirmed with flow cytometry, showing increased surface expression of activated glycoprotein IIb-IIIa and P-selectin. Intracellular SUCNR1 signaling was found to result in decreased cAMP levels, Akt phosphorylation mediated by phosphoinositide 3-kinase-β activation, and receptor desensitization. Furthermore, succinate-induced platelet aggregation was demonstrated to depend on Src, generation of thromboxane A(2), and ATP release. Platelet SUCNR1 is subject to desensitization through both homologous and heterologous mechanisms. In addition, the P2Y(12) receptor inhibitor ticagrelor completely prevented platelet aggregation induced by succinate.

CONCLUSIONS

Our experiments show that succinate induces full aggregation of human platelets via SUCNR1. Succinate-induced platelet aggregation depends on thromboxane A(2) generation, ATP release, and P2Y(12) activation.

ADP mediates inhibition of insulin secretion by activation of P2Y13 receptors in mice

AIMS/HYPOTHESES

To investigate the effects of extracellular purines on insulin secretion from mouse pancreatic islets.

METHODS

Mouse islets and beta cells were isolated and examined with mRNA real-time quantification, cAMP quantification and insulin and glucagon secretion. ATP release was measured in MIN6c4 cells. Insulin and glucagon secretion were measured in vivo after glucose injection.

RESULTS

Enzymatic removal of extracellular ATP at low glucose levels increased the secretion of both insulin and glucagon, while at high glucose levels insulin secretion was reduced and glucagon secretion was stimulated, indicating an autocrine effect of purines. In MIN6c4 cells it was shown that glucose does induce release of ATP into the extracellular space. Quantitative real-time PCR demonstrated the expression of the ADP receptors P2Y(1) and P2Y(13) in both intact mouse pancreatic islets and isolated beta cells. The stable ADP analogue 2-MeSADP had no effect on insulin secretion. However, co-incubation with the P2Y(1) antagonist MRS2179 inhibited insulin secretion, while co-incubation with the P2Y(13) antagonist MRS2211 stimulated insulin secretion, indicating that ADP acting via P2Y(1) stimulates insulin secretion, while signalling via P2Y(13) inhibits the secretion of insulin. P2Y(13) antagonism through MRS2211 per se increased the secretion of both insulin and glucagon at intermediate (8.3 mmol/l) and high (20 mmol/l) glucose levels, confirming an autocrine role for ADP. Administration of MRS2211 during glucose injection in vivo resulted in both increased secretion of insulin and reduced glucose levels.

CONCLUSIONS/INTERPRETATION

In conclusion, ADP acting on the P2Y(13) receptors inhibits insulin release. An antagonist to P2Y(13) increases insulin release and could be evaluated for the treatment of diabetes.

Impact of diagnostic procedures on patient management and hospitalization cost during the 2000 and 2005 enterovirus epidemics in Marseilles, France

Enteroviruses are frequent aetiological agents of central nervous system infections in humans. In 2000 and 2005, two large outbreaks of Echovirus 30 (a member of species human enterovirus B) were observed in the University Hospitals of Marseilles (France). Between the two epidemics, the diagnostic protocols for enterovirus infection were modified, moving from viral cultures and classic RT-PCR in 2000 to real-time RT-PCR in 2005. We compared some viral and epidemiological characteristics of the 2000 and 2005 outbreaks with special attention to diagnostic procedures and to the subsequent clinical management of patients. Despite similar virological and epidemiological characteristics during both outbreaks, our results show that real-time RT-PCR techniques used in 2005 noticeably shortened the period of time necessary to deliver diagnostic results and suggest that this was associated with a decrease in the duration of hospitalization for positive cases. In conclusion, this study suggests that the improvement of enterovirus diagnosis had a major financial impact on the management of the 2005 epidemic in Marseilles and may constitute an interesting example of how new diagnostic methods in microbiology can be self-financed through improvement in patient management.

Ordered nanostructures written directly by laser interference

We present a simplified method to employ laser interference lithography for the fabrication of ordered nanostructures. Neither resist, nor an elaborate fabrication process was needed. Four-beam interference patterns generated in this work included periodic arrays of holes in GaAs, covered with SiO(2) bubbles, and they were directly written into the sample. The diameters of the smallest holes were less than 30 nm. We propose a model to interpret the results.

Monitoring and treatment practices of childhood asthma in Singapore: a questionnaire study

INTRODUCTION

Asthma is the most common chronic disease in children in Singapore. More than 20 percent of children will have been diagnosed with asthma by the age of 15 years. Most children are seen in the primary care setting, thus it is of value to study the management practices, especially of general practitioners, with comparison to gold standards. The aims of the study were to investigate: (a) Methods of monitoring asthma control; (b) Practices in managing acute exacerbations; and (c) Choice of therapy in maintenance treatment.

METHODS

2,100 questionnaires consisting of 35 questions were sent by post to general practitioners and various paediatric doctors throughout Singapore. 173 valid responses were received and results were compared to the 2006 Global Initiative for Asthma guidelines.

RESULTS

76.3 percent of respondents were general practitioners. 89.1 percent did not use symptom score cards / diaries. 37.6 percent did not use peak-flow meters / spirometers. 83.8 percent used a short-acting beta-agonist in acute exacerbations, but only 41.0 percent used oral corticosteroids in outpatients. A significant number used long-acting beta-agonists (LABA) in combination with inhaled steroids (29.5-41.6 percent) or as monotherapy (5.8-8.7 percent) for maintenance treatment. 91.3 percent never used immunotherapy in practice.

CONCLUSION

Greater usage of diaries / score cards can be encouraged along with objective peak flow / spirometry measurements. Management of acute exacerbations is appropriate but corticosteroids are under-prescribed by most doctors. LABA continues to be prescribed for maintenance despite a lack of established safety profile for infants, along with recommendations that they only be used selectively in patients poorly-controlled by medium-dosage inhaled corticosteroids.

Optic neuritis in Singapore

INTRODUCTION

Optic neuritis (ON) is the commonest optic neuropathy encountered in the younger group of patients from the Singapore Neuro-Ophthalmology Study Group. Previous surveys in Asia and our study suggest that ON in Singapore differs from that in Western populations where the majority of cases are associated with multiple sclerosis (MS).

METHODS

Patients satisfying our entry criteria for ON seen between September 2002 and June 2004 were enrolled in the study. The data collected was recorded in a central database and analysed two years later.

RESULTS

The majority (60 percent) of our patients had anterior ON with optic disc swelling (papillitis), were idiopathic in 49.1 percent, and associated with MS in only 25.5 percent. Bilateral cases comprised 16.4 percent of our series and were usually of the anterior variety and mostly idiopathic, although it is still essential to rule out secondary causes. Recurrent ON is indicative of an underlying disease process.

CONCLUSION

The pattern of ON as seen in Singapore differs from that reported in Caucasian studies and from the seminal Optic Neuritis Treatment Trial. We found a higher incidence of optic disc swelling, i.e. anterior ON (papillitis), and a lesser association with MS; visual recovery is similarly good but our recurrence rate is lower.

Review of orbital imaging

CT and MRI are commonly used in the evaluation of patients with suspected orbital disease. Many different diseases may present within this small anatomical space. The purpose of this article is to present a diagnostic strategy based on a compartment model. Localizing pathology to sinus, bone, extraconal space, muscle cone, intraconal space, optic nerve, globe or lacrimal fossa allows significant reduction in the number of differential diagnoses as these compartments contain different tissues which disease may involve or arise from. Certain diseases may also present in multiple compartments. Common diseases which might present in one or multiple compartments will be discussed.

Lentivirus-mediated gene transfer to the rat, ovine and human cornea

Gene therapy of the cornea shows promise for modulating corneal transplant rejection but the most appropriate vector for gene transfer has yet to be determined. We investigated a lentiviral vector (LV) for its ability to transduce corneal endothelium. A lentivector expressing enhanced yellow fluorescent protein (eYFP) under the control of the Simian virus type 40 early promoter (LV-SV40-eYFP) transduced 80-90% of rat, ovine and human corneal endothelial cells as detected by fluorescence microscopy. The kinetics of gene expression varied among species, with ovine corneal endothelium showing a relative delay in detectable reporter gene expression compared with the rat or human corneal endothelium. Vectors containing the myeloproliferative sarcoma virus promoter or the phosphoglycerate kinase promoter were not significantly more effective than LV-SV40-eYFP. The stability of eYFP expression in rat and ovine corneas following ex vivo transduction of the donor cornea was assessed following orthotopic corneal transplantation. Following transduction ex vivo, eYFP expression was maintained in corneal endothelial cells for at least 28 days after corneal transplantation in the sheep and >60 days in the rat. Thus, rat, ovine and human corneal endothelial cells were efficiently transduced by the LV, and gene expression appeared stable over weeks in vivo.

Central pontine myelinolysis

The case is described of a 46 year old female alcoholic, presenting with confusion, jaundice and reduced level of consciousness. The patient was hyponatraemic on admission and despite gradual correction of serum sodium the patient deteriorated neurologically. Magnetic Resonance Imaging scan of the brain revealed characteristic findings of Central Pontine Myelinolysis (CPM). We provide an overview of the first published cases of CPM. The clinical and pathological features of CPM are described. No specific therapy has been shown to improve outcome; current literature advocates supportive management. Identification of patients at risk and gradual correction of hyponatraemia is recommended.

Microalbuminuria prevalence study in hypertensive type 2 diabetic patients in Malaysia

Microalbuminuria is the earliest indicator of diabetic kidney disease and generalised vascular endothelial dysfunction. The Microalbuminuria Prevalence (MAP) Study was carried out to assess the prevalence of macroalbuminuria, microalbuminuria and normoalbuminuria in Asian hypertensive patients with type 2 diabetes on usual care. This paper presents a subanalysis of data from patients in Malaysia. In 733 analysed patients, the prevalence of macroalbuminuria and microalbuminuria was 15.7% and 39.7%, respectively. The high prevalence of diabetic nephropathy in these high-risk patients is a cause for concern, and the Malaysian Health Care system should be prepared for a pandemic of end-stage renal disease due to diabetic nephropathy.

Electrocardiographical case. A man found unconscious

A 25-year-old man was brought to the emergency room after being found unconscious. Electrocardiography (ECG) showed changes classical of tricyclic antidepressant (TCA) poisoning. These included sinus tachycardia, QTc prolongation, QRS complex widening, right axis deviation and positive R waves in lead aVR. This unique ECG highlights the importance of lead aVR, which often tends to be ignored. Treatment is started based on ECG findings.

Skewing of X-chromosome inactivation in three generations of carriers with X-linked chronic granulomatous disease within one family

BACKGROUND

Chronic granulomatous disease (CGD) is an inherited disorder of the innate immune system characterized by impairment of intracellular microbicidal activity of phagocytes. Mutations in one of the four known NADPH-oxidase components preclude generation of superoxide and related antimicrobial oxidants, leading to the phenotype of CGD. Defects in gp91-phox, encoded by CYBB, lead to X-linked CGD, responsible for approximately 70% of all CGD cases. The aim of the study was to evaluate the hypothesis that age-related skewing of X-chromosome inactivation, as described in several CGD families, is caused by preferential survival of bone marrow clones with an inactive NADPH oxidase.

MATERIALS AND METHODS

We studied the neutrophils from three patients and four carriers in three generations of a Turkish family with X-linked CGD. Carrier detection was carried out by the dihydrorhodamine (DHR)-1,2,3 assay, which measures on a per-cell basis the NADPH oxidase-dependent oxidation of DHR by phagocytes. The X-chromosome inactivation pattern was determined with the HUMARA assay in DNA from leucocytes as well as in DNA from a buccal smear of the four carriers.

RESULTS

The three patients were identified by a negative DHR test, and the mutation in their CYBB gene was characterized by DNA sequencing. Moreover, we found an age-related degree of skewing of X-chromosome inactivation in the leucocytes of the four X-CGD carriers, both at the protein level (NADPH oxidase activity) and at the DNA level (HUMARA assay). However, similar skewing of X-chromosome inactivation was found in the buccal DNA from these women.

CONCLUSIONS

These novel findings indicate that the age-related degree of skewing was probably a chance finding, not related to preferential survival of NADPH oxidase-deficient precursor cells, because this enzyme is not expressed in (buccal) epithelial cells.

Validation of various osteoporosis risk indices in elderly Chinese females in Singapore

INTRODUCTION

This study aimed to compare the sensitivity and specificity of various published indices for identifying elderly Chinese females at risk of osteoporosis in Singapore.

METHODS

The indices considered were the Simple Calculated Osteoporosis Risk Estimation (SCORE), the Osteoporosis Risk Assessment Instrument (ORAI), the Age Bulk One or Never Estrogens (ABONE), body weight (WEIGHT), and the Osteoporosis Self-Assessment Tool for Asians (OSTA). Altogether, 135 postmenopausal Chinese female subjects aged 55 years and older participated in the study, and their bone mineral density (BMD) was measured with dual-energy x-ray absorptiometry. Subjects were classified as osteoporotic if their femoral neck BMD T-score was -2.5 or lower. Receiver operating characteristic (ROC) curves were generated to determine the indices' cut-off points, sensitivity, and specificity.

RESULTS

OSTA had the highest discriminatory power, with an estimated area under the ROC curve of 0.82. This was followed by SCORE (0.80), WEIGHT (0.78), ORAI (0.76), and ABONE (0.70). At the cut-off point of -2, OSTA achieved sensitivity and specificity of 91% and 59%, respectively.

CONCLUSION

The study showed that OSTA is an effective index for identifying postmenopausal women at risk for osteoporosis.

Differential expression of splice variant and wild-type parkin in sporadic Parkinson's disease

BACKGROUND

Altered splicing of parkin under cellular stress could lead to changes in gene expression and altered protein activity. The causative role of parkin in sporadic Parkinson's disease (PD) is unknown.

OBJECTIVES

We described a parkin splice variant (SV) in the substantia nigra and leukocytes of sporadic PD patients. Using a case control methodology, we investigated the exon 4 SV (E4SV) and wild-type parkin expression in the leukocytes of sporadic PD patients and healthy individuals.

METHODS/RESULTS

We identified a parkin E4SV in the substantia nigra and leukocytes of sporadic PD patients and controls by reverse transcriptase-polymerase chain reaction (PCR). The exon 4 (122 bp) deletion resulted in a reading frame shift over the junction of exons 3-5 and a stop codon (tga) 17 bp downstream from exon 3. The translated truncated protein was associated with a total loss of the two-RING finger functional domain. Utilizing TaqMan real-time PCR with probes located across the junction of exons 3-4 or 3-5, we demonstrated an over-expression of E4SV/wild-type parkin ratio in the leukocytes of sporadic PD patients compared to age-, gender-, and race-matched controls (p<0.0005). A multivariate regression analysis demonstrated that the ratio of E4SV/wild-type parkin expression increased with age in PD patients, but this was not observed in the controls (p<0.0005).

CONCLUSION

The relative expression of E4SV/wild type parkin was increased in sporadic PD compared to healthy controls. Based on our observations, further functional studies to determine the pathophysiologic role of E4SV in sporadic PD patients will be of importance.

A prospective randomized controlled trial of suction versus non-suction to the under-water seal drains following lung resection

OBJECTIVE

Practice varies as to whether or not suction is applied to under-water seal drains following lung surgery. We tested the null hypothesis that there is no difference with respect to air leak duration.

METHODS

Patients undergoing thoracotomy or video assisted thoracoscopic surgery for lobectomy or wedge resection had either low-pressure suction or no suction applied to their underwater seal bottles postoperatively. Patients were allocated using minimization, a method of unbiased allocation ensuring balance between the arms of a trial with respect to known or suspected confounding factors. The trial was powered for duration of air leak. If an air leak persisted on the 7th post-operative day, the surgeon determined further management. Kaplan-Meier survival analysis of air leak duration and a log rank test were performed on an intention-to-treat basis, with observations censored at 144h (6 complete days).

RESULTS

Of the 254 patients that entered the trial, data were available for analysis for 239 (123 no-suction and 116 suction). There was no significant difference in the cumulative persistence of air leaks between the two groups (P=0.62) and inspection of the Kaplan-Meier curves suggests that any difference is negligible.

CONCLUSIONS

Applying suction to the underwater seal drains following lung surgery makes no difference in terms of air leak duration. In the light of this finding we have adopted a uniform policy of no suction being applied to the underwater seal, from the time of surgery, unless a specific clinical judgment is made to use it. The anticipated gains are that this will reduce work and cost and aid mobilization.

Alvarado score: an admission criterion in patients with right iliac fossa pain

Appendicitis is an important differential diagnosis in patients with right iliac fossa pain. The diagnosis in patients with equivocal signs can be difficult. Many patients with suspected appendicitis are admitted for observation. We studied the Alvarado scores of 175 patients who presented to the emergency department with right iliac fossa pain and found that patients with scores of 4 or less did not have appendicitis. We also present an algorithm incorporating the Alvarado score for patients with suspected appendicitis.