Endoplasmic reticulum stress upregulates protein tyrosine phosphatase 1B and impairs glucose uptake in cultured myotubes

AIMS/HYPOTHESIS

Endoplasmic reticulum (ER) stress has been recognised as a common pathway in the development of obesity-associated insulin resistance. Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signalling and is localised on the ER membrane. The aim of the study was to investigate the cross-talk between ER stress and PTP1B.

METHODS

Leptin-deficient obese (ob/ob), Ptp1b (also known as Ptpn1) knockout and C57BL/6J mice were subjected to a high-fat or normal-chow diet for 20 weeks. ER stress was induced in cultured myotubes by treatment with tunicamycin. Immunohistochemistry and western blotting were used to assess proteins involved in the ER stress response. Myotube glucose uptake was determined by measuring 2-deoxy[(3)H]glucose incorporation.

RESULTS

A high-fat diet induced ER stress and PTP1B expression in the muscle tissue of mice and these responses were attenuated by treatment with the ER chaperone tauroursodeoxycholic acid (TUDCA). Cultured myotubes exhibited increased levels of PTP1B in response to tunicamycin treatment. Silencing of Ptp1b with small interfering RNA (siRNA) or overexpression of Ptp1b with adenovirus construct failed to alter the levels of ER stress. Ptp1b knockout mice did not differ from the wild-type mice in the extent of tunicamycin-induced upregulation of glucose-regulated protein-78. However, tunicamycin-induced phosphorylation of eukaryotic initiation factor 2α and c-Jun NH(2)-terminal kinase-2 were significantly attenuated in the Ptp1b knockout mice. Treatment with TUDCA or silencing of PTP1B reversed tunicamycin-induced blunted myotube glucose uptake.

CONCLUSIONS/INTERPRETATION

Our data suggest that PTP1B is activated by ER stress and is required for full-range activation of ER stress pathways in mediating insulin resistance in the skeletal muscle.

Ruptured uterine artery pseudoaneurysm: an overlooked cause of late postpartum haemorrhage

We report an exceptional case of secondary postpartum hemorrhage (PPH) twenty days after cesarean delivery, resulting from a ruptured uterine artery pseudoaneurysm (UAP). The diagnosis was initially confounded by a septic shock necessitating inotropic support in the intensive care unit. Intense vaginal bleeding occurred eleven days after uterine curettage. Doppler ultrasound showed an anechoic focus in the inferior part of the uterus with turbulent flow. Bilateral internal iliac artery angiograms revealed a left uterine artery pseudoaneurysm that was successfully embolized. UAP is a rare cause of unexplained PPH that requires a high index of suspicion for diagnosis. This first report in the anesthesia literature serves to focus our awareness on its possible occurrence, and gives track to its management. Pitfalls in UAP diagnostic are highlighted (delayed presentation, possibility of spontaneous hemostasis, and lack of typical findings on colour Doppler sonography in hypotensive patients). These pitfalls may further be confounded by a concomitant sepsis. Angiography and selective uterine artery embolization is the treatment of choice.

Expression of Orseolia oryzae nucleoside diphosphate kinase (OoNDPK) is enhanced in rice gall midge feeding on susceptible rice hosts and its over-expression leads to salt tolerance in Escherichia coli

The Asian rice gall midge, Orseolia oryzae, is a major dipteran pest of rice, with many known biotypes. The present investigation was initiated to understand the molecular mechanisms of infestation for developing novel integrated pest management strategies. We isolated and characterized a gene, nucleoside diphosphate kinase (OoNDPK), from the rice gall midge, encoding a protein with 169 amino acid residues and with a secretory signal sequence - an observation that assumes significance as salivary gland secretions have been implicated to play a major role in insect-plant interactions. Furthermore, up-regulation (> 18 folds) of OoNDPK was observed in the salivary glands of maggots feeding on susceptible host in contrast to those feeding on resistant host. Phylogenetic analysis revealed similarity of OoNDPK with its dipteran orthologues. 3DLigandSite analysis, of the predicted OoNDPK and its orthologues, revealed phenylalanine and tyrosine residues to be specifically present in NDPK proteins from the plant feeders. Results suggest secretion of OoNDPK into the host plant and its probable involvement in gall midge-rice interaction. Using the coleoptile cell elongation assay, we demonstrated that the recombinant OoNDPK is capable of causing elongation of rice coleoptile cells. Additionally, heterologous expression of OoNDPK in Escherichia coli increased the tolerance of these cells to salt (NaCl; up to 1 mM), hinting at the involvement of this gene in abiotic stress response as well.

Sequential interactions of silver-silica nanocomposite (Ag-SiO2 NC) with cell wall, metabolism and genetic stability of Pseudomonas aeruginosa, a multiple antibiotic-resistant bacterium

The study was carried out to understand the effect of silver-silica nanocomposite (Ag-SiO(2) NC) on the cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, a multiple drug-resistant bacterium. Bacterial sensitivity towards antibiotics and Ag-SiO(2) NC was studied using standard disc diffusion and death rate assay, respectively. The effect of Ag-SiO(2) NC on cell wall integrity was monitored using SDS assay and fatty acid profile analysis, while the effect on metabolism and genetic stability was assayed microscopically, using CTC viability staining and comet assay, respectively. Pseudomonas aeruginosa was found to be resistant to β-lactamase, glycopeptidase, sulfonamide, quinolones, nitrofurantoin and macrolides classes of antibiotics. Complete mortality of the bacterium was achieved with 80 μg ml(-1) concentration of Ag-SiO(2) NC. The cell wall integrity reduced with increasing time and reached a plateau of 70% in 110 min. Changes were also noticed in the proportion of fatty acids after the treatment. Inside the cytoplasm, a complete inhibition of electron transport system was achieved with 100 μg ml(-1) Ag-SiO(2) NC, followed by DNA breakage. The study thus demonstrates that Ag-SiO(2) NC invades the cytoplasm of the multiple drug-resistant P. aeruginosa by impinging upon the cell wall integrity and kills the cells by interfering with electron transport chain and the genetic stability.

SIGNIFICANCE AND IMPACT OF STUDY

Although the synthesis, structural characteristics and biofunction of silver nanoparticles are well understood, their application in antimicrobial therapy is still at its infancy as only a small number of microorganisms are tested to be sensitive to nanoparticles. A thorough knowledge of the mode of interaction of nanoparticles with bacteria at subcellular level is mandatory for any clinical application. The present study deals with the interactions of Ag-SiO2NC with the cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, which would contribute substantially in strengthening the therapeutic applications of silver nanoparticles.

Emerging roles for modulation of microRNA signatures in cancer chemoprevention

miRNAs are small endogenous non-coding RNAs, approximately 21-nucleotides in length, which are shown to regulate an array of cellular processes such as differentiation, cell cycle, cell proliferation, apoptosis, and angiogenesis which are important in cancer. miRNAs can function as both tumor promoters (oncomiRs) or tumor suppressors by their ability to target numerous biomolecules that are important in carcinogenesis. Aberrant expression of miRNAs is correlated with the development and progression of tumors, and the reversal of their expression has been shown to modulate the cancer phenotype suggesting the potential of miRNAs as targets for anti-cancer drugs. Several chemopreventive phytochemicals like epigallocatechin-3-gallate, curcumin, isoflavones, indole-3-carbinol, resveratrol, and isothiocyanate have been shown to modulate the expression of numerous miRNAs in cancer cells that lead to either abrogation of tumor growth or sensitization of cancer cells to chemotherapeutic agents. This review focuses on the putative role(s) of miRNAs in different aspects of tumorigenesis and at various stages of early drug discovery that makes them a promising class of drug targets for chemopreventive intervention in cancer. We summarize the current progress in the development of strategies for miRNA-based anti-cancer therapies. We also explore the modulation of miRNAs by various cancer chemopreventive agents and the role of miRNAs in drug metabolism. We will discuss the role of miRNAs in cancer stem cells and epithelial-to-mesenchymal transition; and talk about how modulation of miRNA expression relates to altered glycosylation patterns in cancer cells. In addition, we consider the role of altered miRNA expression in carcinogenesis induced by various agents including genotoxic and epigenetic carcinogens. Finally, we will end with a discussion on the potential involvement of miRNAs in the development of cancer chemoresistance. Taken together, a better understanding of the complex role(s) of miRNAs in cancer may help in designing better strategies for biomarker discovery or drug targeting of miRNAs and/or their putative protein targets.

Quantitative adjustment for macroprolactin is an integral part of laboratory assessment of hyperprolactinaemia

INTRODUCTION

Prolactin circulates predominantly as a 23-kDa monomer, and a high-molecular-weight form largely consisting of a complex of prolactin and an anti-prolactin IgG autoantibody, called macroprolactin. This cross-reacts with conventional laboratory assays for prolactin. We here describe how quantitative adjustment for this may assist patient management.In a consecutive series of 218 patients with prolactin elevated to 400 mu/L or more in men (normal range ≤ 180) (n=79, 36.2% of sample) and 1 000 mu/L or more in women (normal range ≤ 500) (n=139, 63.8%) a macroprolactin screen was performed using PEG precipitation.

RESULTS

Where present, median macroprolactin as a proportion of total prolactin was in women 13% (percentile 25-percentile 75: 7-25%) and in men 15% (7-30%).The distribution of macroprolactin as a proportion of total prolactin was markedly skewed to the left with 69.7% of women and 62.9% of men having macroprolactin proportion of 20% or less. There was no relation between %macroprolactin and total measured prolactin, age or gender.Of relevance to clinical management, in 24% of men and 20.5% of women, correction for estimated macroprolactin gave an adjusted monomeric prolactin level below the agreed threshold for further investigation, potentially avoiding unnecessarily referral.In our clinical series, quotation of an adjusted monomeric prolactin would have resulted in unnecessary further investigation being avoided in a number of cases.

DISCUSSION

Screening for macroprolactin is a key element of laboratory assessment for hyperprolactinaemia.In cases where measured total prolactin is significantly raised, quantitative reporting of estimated monomeric prolactin instead of just 'macroprolactin' positive' can avoid unnecessary investigations.

Risk factors for under-nutrition among children aged one to five years in Udupi taluk of Karnataka, India: A case control study

BACKGROUND

Despite her apparent economic success, India is plagued by a high burden of under-nutrition among children under five. This study was aimed at understanding some of the risk factors for under-nutrition in a region with favourable maternal and child health indicators.

METHOD

A case control study was carried out among children aged one to five years attending the paediatric outpatient department in six rural health care centres in Udupi taluk of Karnataka in Southern India. A total of 162 children were included in the study, of which 56 were cases. A semi-structured questionnaire was used to interview the caregivers of the children and the nutritional status was graded according to the Indian Academy of Paediatrics (IAP) grading of protein-energy malnutrition.

RESULTS

Under-nutrition was associated with illness in the last one month [OR- 4.78 (CI: 1.83 -12.45)], feeding diluted milk [OR-14.26 (CI: 4.65 - 43.68)] and having more than two children with a birth interval ≤2 years [OR- 4.93 (CI: 1.78 - 13.61)]. Lack of exclusive breast feeding, level of education of the caregiver and environmental factors like source of water did not have an association.

CONCLUSION

Childhood illness, short birth interval and consumption of diluted milk were some of the significant contributory factors noted among this population. Information, Education, Communication (IEC) campaigns alleviating food fads and promoting birth spacing is needed.

Host susceptibility to tuberculosis: insights from a longitudinal study of gene expression in diabetes

Tuberculosis (TB) remains a major global disease, and diabetes, which is documented to increase susceptibility to TB threefold, is also becoming pandemic. This susceptibility has been attracting extensive research interest. The increased risk of TB in diabetes may serve as a unique model to understand host susceptibility to specific pathogens in humans. To examine this rationale, we investigated the expression of reported TB candidate genes in a longitudinal diabetes study. Two genes, HK2 and CD28, emerged as potential culprits in diabetes-increased TB susceptibility.

Trichuris sp. and Strongyloides sp. infections in a free-ranging baboon colony

We conducted cross-sectional surveys of parasites infecting a large free-living colony of baboons at the Southwest National Primate Research Center in San Antonio in October 2003 and April 2004, immediately before, and 6 mo after, treatment with ivermectin. Trichuris sp. was the predominant species present, infecting 79 and 69% of individual animals in the 2 surveys, with fecal egg counts (FEC) of up to 60,200 eggs per g (epg) (mean = 1,235 in October 2003 and 1,256 in April 2004). Prevalence remained fairly stable across age groups, and intensity was highest in animals <1 or >15 yr old, in contrast to patterns observed in humans, where school-age children show the heaviest infections. Strongyloides sp. was also identified, but the species identity remains uncertain. Small subunit ribosomal DNA sequences differed from published sequences of Strongyloides fuelleborni at multiple sites, but resided in a monophyletic group with other Strongyloides species with 92% bootstrap support. This may reflect a recent acquisition from a local host, or that the published sequence of S. fuelleborni is incorrect. Widespread infections with 2 nematode genera in a free-ranging baboon colony that are an important source of morbidity in human populations provide a useful model system for work on the epidemiology, control, pathology, and genetics of these parasites in a host species that is physiologically, immunologically, and genetically similar to humans.

Prevalence of Noise Induced Hearing Loss in Indian Air Force Personnel

BACKGROUND

Noise exposure is an inherent part of duty of the aircrew and maintenance staff in the Indian Air Force (IAF). An audiometric survey of IAF personnel was carried out to analyze the prevalence and severity of noise induced hearing loss (NIHL).

METHODS

An audiometric study of 1000 IAF personnel of various trades, age and exposure groups were carried out at an operational base. Age related correction of 5 dB per decade was applied for personnel above SO years of age. Personal factors like smoking, blood group and use of ear defenders were analysed for their effect on the prevalence of NIHL.

RESULT

The study revealed an overall incidence of NIHL of 22.9 % in the personnel with a higher prevalence among the technical trades (26.18 %) as compared to non technical trades (12.5 %). There was a significant increase in prevalence of hearing loss with duration of exposure with 50.8% of personnel above 30 years of exposure having hearing loss. A higher incidence of hearing loss was observed in personnel of blood group O and smokers whereas use of ear defenders was protective.

CONCLUSION

The study reveals a significantly increased prevalence of NIHL among the technical trades of the IAF personnel. The deleterious effects of smoking and protective effect of regular use of ear defenders are emphasized.

Antiplatelet antibodies in cases of Glanzmann's thrombasthenia with and without a history of multiple platelet transfusion

Antiplatelet antibodies are known to be present in a wide spectrum of patients, which include chronic Idiopathic Thrombocytopenic Purpura (ITP), infections, etc., including Glanzmann's thrombasthenia (GT) patients who receive multiple platelet transfusions. The presence of natural antibodies to platelet receptors is not studied in cases of GT. We studied the antiplatelet antibodies in 23 patients with GT, 15 of which had received multiple transfusions and eight that had not received transfusions, along with 50 cases of chronic ITP. The prevalence and specificity of platelet-bound antibodies were detected by inhibition assays using O-group platelets on flow cytometry. The mean antiplatelet antibodies in 15 patients of GT who had not received transfusions and eight patients with multiple transfusions was 8427 + 2131.88 and 9038 + 2856 antibodies/platelet, respectively, while in case of the 50 ITP patients studied, it was 22166 + 5616 antibodies/platelet (Normal Range 1500–3200 antibodies/platelet). We conclude that GT patients who have not received transfusions may develop antiplatelet antibodies to the missing/abnormal receptor. Whether this is due to a molecular mimicry or due to some other mechanism needs to be explored.

The four-variable modification of diet in renal disease formula underestimates glomerular filtration rate in obese type 2 diabetic individuals with chronic kidney disease

AIMS/HYPOTHESIS

GFR is commonly estimated using the four-variable Modification of Diet in Renal Disease (MDRD) formula and this forms the basis for classification of chronic kidney disease (CKD). We investigated the effect of obesity on the estimation of glomerular filtration rate in type 2 diabetic participants with CKD.

METHODS

We enrolled 111 patients with type 2 diabetes mellitus in different stages of CKD. GFR was measured using (51)Cr-labelled EDTA plasma clearance and was estimated using the four-variable MDRD formula.

RESULTS

The bias between estimated and measured GFR was -22.4 (-33.8 to -11.0) p < 0.001 in the obese group compared with -6.04 (-17.6 to -5.5) p = 0.299 in the non-obese group. When GFR was indexed to body surface area of 1.73 m(2), the bias remained significant at -9.4 (-13.4 to -5.4) p < 0.001 in the obese participants.

CONCLUSIONS/INTERPRETATION

This study suggests that the four-variable MDRD formula significantly underestimates GFR in obese type 2 diabetic participants with CKD.

Bilateral thalamic lesions

OBJECTIVE

Bilateral thalamic lesions are rare and relatively obscure neoplasms. We present our experience with nine cases of bilateral thalamic lesions and attempt to analyse them in the background of available literature.

MATERIALS AND METHODS

Retrospective analyses of the case records of 9 cases of bilateral thalamic lesions treated in our department since January 2002, which have a minimum of 1 year follow-up.

RESULTS

The study group included four males and five females with a mean age of 14.6 years (5 years to 29 years). Seven of these patients had radiological evidence of bilateral thalamic lesions at presentation and 2 patients had involvement of the opposite thalamus at a later stage of the disease. All patients except one presented with raised intracranial pressure symptoms. Focal motor deficits (4/9), behavioral and memory disturbances (3/9) were the other major presenting symptoms. Biopsy confirmation was possible in six patients and histopathology was suggestive of low grade fibrillary astrocytoma in all six patients. Seven patients required CSF diversion procedure for associated hydrocephalus. Eight of our nine patients underwent radiotherapy. On last follow-up, 3 patients were clinically stable with images suggestive of arrested disease, four patients had evidence of progressive disease both clinically and radiologically and there were two recorded cases of mortality.

CONCLUSION

Primary bilateral thalamic lesions have characteristic neuroradiological properties and are distinct from unilateral thalamic tumours with bilateral progression. Almost all of these lesions on histology prove to be gliomas but decompressive surgery is seldom feasible. Surgical intervention is limited to biopsy and CSF diversion for hydrocephalus. Bilateral thalamic lesions remain unresponsive to adjuvant therapy and generally carry a poor prognosis.

The fate and significance of retained staples after stapled haemorrhoidopexy

AIM

We studied the fate of staples after stapled haemorrhoidectomy (SH) and reviewed the complications they may cause.

METHOD

A survey was carried among 16 surgeons experienced at performing SH to assess their knowledge regarding retained staples. In addition, plain pelvic radiology was used to visualize residual staples at different time intervals after SH in 45 patients.

RESULTS

Ten (63%) surgeons informed their patients that the staples would be shed within 3 months of SH. Regardless of the timing of surgery, part of the staple line was radiologically visible in all patients, and in 19 patients (45%) the staple line was completely visible.

CONCLUSION

Contrary to the common belief, the majority of staples are retained after SH.

Migraine may be a risk factor for the development of complex regional pain syndrome

The aim was to assess the relative frequency of migraine and the headache characteristics of complex regional pain syndrome (CRPS) sufferers. CRPS and migraine are chronic, often disabling pain syndromes. Recent studies suggest that headache is associated with the development of CRPS. Consecutive adults fulfilling International Association for the Study of Pain criteria for CRPS at a pain clinic were included. Demographics, medical history, and pain characteristics were obtained. Headache diagnoses were made using International Classification of Headache Disorders, 2nd edn criteria. Migraine and pain characteristics were compared in those with migraine with those without. anova with Tukey post hoc tests was used to determine the significance of continuous variables and Fisher's exact or χ(2) tests for categorical variables. The expected prevalence of migraine and chronic daily headache (CDH) was calculated based on age- and gender-stratified general population estimates. Standardized morbidity ratios (SMR) were calculated by dividing the observed prevalence of migraine by the expected prevalence from the general population. The sample consisted of 124 CRPS participants. The mean age was 45.5 ± 12.0 years. Age- and gender-adjusted SMRs showed that those with CRPS were 3.6 times more likely to have migraine and nearly twice as likely to have CDH as the general population. Aura was reported in 59.7% (74/124) of participants. Of those CRPS sufferers with migraine, 61.2% (41/67) reported the onset of severe headaches before the onset of CRPS symptoms Mean age of onset of CRPS was earlier in those with migraine (34.9 ± 11.1 years) and CDH (32.5 ± 13.4 years) compared with those with no headaches (46.8 ± 14.9 years) and those with tension-type headache (TTH) (39.9 ± 9.9 years), P < 0.05. More extremities were affected by CRPS in participants with migraine (median of four extremities) compared with the combined group of those CRPS sufferers with no headaches or TTH (median 2.0 extremities), P < 0.05. The presence of static, dynamic and deep joint mechano-allodynia together was reported by more CRPS participants with migraine (72.2%) than those with no headaches or TTH (46.2%), P ≤ 0.05. Migraine may be a risk factor for CRPS and the presence of migraine may be associated with a more severe form of CRPS. Specifically: (i) migraine occurs in a greater percentage of CRPS sufferers than expected in the general population; (ii) the onset of CRPS is reported earlier in those with migraine than in those without; and (iii) CRPS symptoms are present in more extremities in those CRPS sufferers with migraine compared with those without. In addition, as we also found that the presence of aura is reported in a higher percentage of those CRPS sufferers with migraine than reported in migraineurs in the general population, further evaluation of the cardiovascular risk profile of CRPS sufferers is warranted.

Kissing anterior communicating artery aneurysms: diagnostic dilemma and management issues

Kissing aneurysms are unusual and relatively rare types of multiple intracranial arterial aneurysms. When located on the anterior communicating artery (ACoA), kissing aneurysms pose considerable diagnostic difficulty on preoperative conventional angiogram. Special angiographic views or 3D rotational angiogram are needed to make the correct diagnosis and to avoid interpreting them as multilobed or bilobed saccular aneurysms on preoperative conventional angiogram. Treatment of these aneurysms, either by clipping or coiling, needs to be individualized. Unique problems which need to be addressed during surgical clipping are high risk of rupture due to dense adhesions between the kissing aneurysms, requirement of at least two clips in a narrow working area, the aneurysm that needs to be clipped first and interference of the first clip with application of subsequent clips. The authors present a case of a 63-year-old male who had kissing ACoA aneurysms managed successfully by clipping.