Ab-initio adsorption study of chitosan on functionalized graphene: critical role of van der Waals interactions

We investigate the adsorption process of an organic biomolecule (chitosan) on epoxy-functionalized graphene using ab-initio density functional methods incorporating van-der-waals (vdW) interactions. The role of London dispersion force on the cohesive energy and conformal preference of the molecule is quantitatively elucidated. Functionalizing graphene with epoxy leads to weak hydrogen-bond interactions with chitosan. Binding energy values increase by over an order of magnitude after including vdW corrections, implying that dispersive interactions dominate the physisorption process. Conformal study show binding upto 30 kcal/mol when the molecule is oriented with the hydroxyl group approaching the functionalized graphene. Our study advances the promise of functionalized graphene for a variety of applications.

Prevalence of diabetes among hypothyroid subjects

Thyroid dysfunction affects a significant portion of the general population. Most studies have found a higher prevalence of hypothyroidism in women, increasing with age. Prevalence of hyperthyroidism has been found to range 0.5-3.0%. Type 2 diabetes is a major public health problem affecting approximately 4.8 percent of the Bangladeshi population. The study was designed to see the prevalence of type 2 diabetes in hypothyroid patients of any etiology. Four hundred forty two consecutive cases of diagnosed hypothyroidism were recruited in the study. All diagnosed hypothyroid subjects (sub-clinical or overt) reported in one year not known to be diabetic previously, underwent standard OGTT (FPG and 2-hour post 75 gram glucose) before initiation of thyroid hormone replacement. Newly detected diabetes among the subjects diagnosed as hypothyroidism is significantly higher 4.8 vs. 7.01% (p<0.01) and the prevalence of pre-diabetic state Impaired Glucose Tolerance (IGT) is also higher (11% vs. 12.6%) among hypothyroid subjects. Pure IFG (FPG ≥6.1 mmol/l but <7.0 mmol/l, and 2-PG <7.8 mmol/l) was found in 5.2% according to WHO criteria and the prevalence is higher (6.8%) with ADA criteria (considering normal FBG <5.6mmol/l). Diabetes was found in 7.01% among hypothyroid subjects which is higher than the existing known prevalence (4.8%). IGT was also found higher among hypothyroid subjects than population prevalence (8.6%). Further larger sample study is essential to establish the findings.

Lifetime-enhanced transport in silicon due to spin and valley blockade

We report the observation of lifetime-enhanced transport (LET) based on perpendicular valleys in silicon by transport spectroscopy measurements of a two-electron system in a silicon transistor. The LET is manifested as a peculiar current step in the stability diagram due to a forbidden transition between an excited state and any of the lower energy states due to perpendicular valley (and spin) configurations, offering an additional current path. By employing a detailed temperature dependence study in combination with a rate equation model, we estimate the lifetime of this particular state to exceed 48 ns. The two-electron spin-valley configurations of all relevant confined quantum states in our device were obtained by a large-scale atomistic tight-binding simulation. The LET acts as a signature of the complicated valley physics in silicon: a feature that becomes increasingly important in silicon quantum devices.

Clinical and laboratory parameters of pleural tuberculosis

This prospective observational clinical study was done to find out the clinical and laboratory parameters of pleural tuberculosis patients, to find out a sensitive and specific tool for diagnosis and to see the effectively of a standard anti-TB regime Isoniazide, Rifampicine, Pyrazinamide, Ethambutol, (2HRZE/4HR) for treatment of pleural tuberculosis in an adult medicine unit, department of Medicine, Chittagong Medical College Hospital, Chittagong, Bangladesh. A series of total thirty-three consecutive pleural tuberculosis patients admitted in that unit over a period of 6 months were enrolled. All thirty-three pleural tuberculosis patients were observed for their demographic and clinical parameters and undergone some relevant investigations like complete blood count, Mantoux test, pleural fluid study and pleural histopathological study. Later on, they were put on anti-tuberculosis therapy without steroid and followed their response after one month. All patients of pleural tuberculosis presented in this medicine unit had fever and cough associated with chest pain (87.9%), dysnoea (42.4%), haemoptysis (9.1%), weight loss (84.4%), anorexia (90.9%). Age of presentation was 34.1+/-16.2 years and of them, 60.7% patients were below 30. Mean Erythrocyte Sedimentation Rate (ESR) was 97.04 mm in 1st hour and 57.6% cases had ESR more than 100. 63.6% had Mantoux Test (MT) positive (>10 mm). Only 6.1% had hemorrhagic effusion and others had straw colored fluid. Mean pleural fluid protein is 5.9 gram/L and sugar 65.7 mg/dl. No Acid Fast Bacilli (AFB) was seen on microscopy in pleural fluid. Pleural biopsy revealed 54.5% granulomatous lesion with or without caseation and another 24.2% shows chronic inflammation. Seventy seven percentage (77%) patients were attended follow-up clinic after 1 month and all patients (100%) were improved with this anti-TB therapy. Of the total patient treated with anti TB drug, 53.5% had no pleural effusion, other had minimum effusion. Only 6.06% require subsequent steroid addition and other measures. Pleural biopsy is the investigations of choice for pleural tuberculosis especially in resource poor countries. Pleural tuberculosis can be treated with a standard anti-TB regime successfully without steroid.

Severity of leukoaraiosis correlates with clinical outcome after ischemic stroke

BACKGROUND

Leukoaraiosis (LA) is closely associated with aging, a major determinant of clinical outcome after ischemic stroke. In this study we sought to identify whether LA, independent of advancing age, affects outcome after acute ischemic stroke.

METHODS

LA volume was quantified in 240 patients with ischemic stroke and MRI within 24 hours of symptom onset. We explored the relationship between LA volume at admission and clinical outcome at 6 months, as assessed by the modified Rankin Scale (mRS). An ordinal logistic regression model was developed to analyze the independent effect of LA volume on clinical outcome.

RESULTS

Bivariate analyses showed a significant correlation between LA volume and mRS at 6 months (r = 0.19, p = 0.003). Mean mRS was 1.7 +/- 1.8 among those in the lowest (< or =1.2 mL) and 2.5 +/- 1.9 in the highest (>9.9 mL) quartiles of LA volume (p = 0.01). The unfavorable prognostic effect of LA volume on clinical outcome was retained in the multivariable model (p = 0.002), which included age, gender, stroke risk factors (hypertension, diabetes mellitus, atrial fibrillation), previous history of brain infarction, admission plasma glucose level, admission NIH Stroke Scale score, IV rtPA treatment, and acute infarct volume on MRI as covariates.

CONCLUSIONS

The volume of leukoaraiosis is a predictor of clinical outcome after ischemic stroke and this relationship persists after adjustment for important prognostic factors including age, initial stroke severity, and infarct volume.

Identification of microbial faecal sources in the New River in the United States-Mexican border region

Water samples were analysed to differentiate human and animal faecal contamination of the New River, Mexico/USA, by genotyping bacterial viruses detected in the samples. From 46 water samples collected from the New River, 372 plaques of male-specific coliphages were isolated and genotyped; 44% of the plaques were identified as F-RNA coliphages and further characterized into four groups. Group I was the most prevalent (56%), followed by group IV (25%), group III (10%) and group II (9%). Group III coliphages were only detected at the sampling site in the vicinity of the international boundary, indicating human faecal contamination. As the New River traverses through the US region, groups I and IV coliphages were predominantly identified, but no human-specific genotypes were detected. The study also found that water temperature influenced the prevalence of the relative proportions of F-RNA coliphages in the environmental water samples. The strategy used in this study appears to be a practical and reliable tool for monitoring and distinguishing between human and animal faecal contamination.

Psychological Distress Among Patients of an Orthopaedic Out Patient Clinic: Study from a Low Income Country

In high income countries depression is common among general trauma patients and is associated with a poor outcome. In the absence of previous reports from a developing country we evaluated the relationship of psychological distress to physical injury, musculoskeletal complaints, and social factors in Pakistan.

Methods:

One thousand and fourteen patients were recruited from a busy orthopaedic outpatient clinic at a general hospital in Karachi (90.5% response rate). Research assistants administered the Self Rating Questionnaire (SRQ) to measure psychological distress, the Oslo social support questionnaire, and the Brief Disability Questionnaire (BDQ). The surgeons documented the diagnosis and, if appropriate, rated symptoms as medically unexplained.

Results:

An SRQ score of 9 or more, which indicates probable depressive disorder, occurred in 45.6% of men & 76.1% of women. A high SRQ score was associated with female sex, divorced, separated or widowed status, little or no education, low income and little social support. Even after these were controlled for there was a significantly higher SRQ score in patients with arthritis, backache/prolapsed intervertebral disc, major fracture and other bone pathology. Overall there was no difference in SRQ score between patients with medically explained (by trauma or organic disease) or unexplained symptoms.

Conclusions:

Depressive disorder appears to be very common in orthopaedic out patients in this low income country and both social circumstances and nature of bone pathology are associated with such depression. Treatment should address this extreme psychological distress.

Taking the next step in 2005, the year of the diabetic foot

OBJECTIVES

To determine the age-standardized rate of lower limb amputations among Type 2 diabetics admitted to the Port of Spain General Hospital (POSGH), San Fernando General Hospital (SFGH) and Sangre Grande County Hospital (SGCH) for the period 2000-2004. To determine in-hospital mortality following amputation, for the same period. To determine the risk factors that contributed to diabetic foot complications.

DESIGN AND METHODS

All patients who had a lower limb amputation at the three major public health institutions in Trinidad during the study period were enrolled. In addition patients attending the surgical out-patient clinic and currently admitted to the ward with a diabetic septic foot was selected for the administration of a questionnaire to determine the major contributing factors. Data on the type of amputation, age, sex, ethnicity, from which an age-standardized mortality rate, was determined for the age group 30-60.

RESULTS

Of 822 patient files examined, 515 (80%) of these major amputations were performed on Type 2 diabetics, of which 352 (68%) were AKA and 163 (32%) were BKA. The AKA:BKA ratio for the period 2000-2004 was 2.2:1. There was a significant difference between the mean ages at which females had a major amputation to males (p=0.001). The overall ratio of Africans to South East Asians was 1.5:1 amongst the Type 2 diabetic amputees. For major amputations the average length of stay was found to be 22.5 (0-192) days. The age-standardized rate for the age group 30-60 was 13.85 per 100,000 for 2004. Of 66 deaths, 31 (47%) were septicemia cases and 14 (21%) cardio-respiratory failure cases. Finally, of 97 persons interviewed, the major causative agent for diabetic foot complications and amputations was foot trauma (51%).

CONCLUSION

Type 2 diabetic amputation status of Trinidad would seem to have improved as shown by this study. However, steps must be taken to improve patient awareness about prevention and care of the diabetic foot. Doctors must also seek to increase their vigilance when screening diabetic patient in the primary care setting in order to prevent the late detection and treatment of the septic lower limb.

Serum concentrations of retinol-binding protein 4 in women with and without gestational diabetes

AIMS/HYPOTHESIS

Pregnancy is characterised by temporarily increased insulin resistance. Gestational diabetes occurs when pancreatic beta cell function is unable to compensate for this insulin resistance. Retinol-binding protein 4 (RBP4) could be related to insulin resistance. We hypothesised that RBP4 is elevated in gestational diabetes.

METHODS

Serum RBP4, transthyretin and retinol were cross-sectionally measured in 42 women with gestational diabetes and 45 pregnant controls. Of these, 20 women with and 22 without gestational diabetes were included in an additional longitudinal study. RBP4 was determined by enzyme immunometric assay (EIA) and western blot.

RESULTS

Women with gestational diabetes had lower RBP4 EIA and western blot levels than controls (median 6.8 [interquartile range, 3.9-14.3] vs 11.3 [7.8-19.9] microg/ml, p < 0.001 and 25.1 [21.7-29.6] vs 26.6 [23.5-32.2] microg/ml, p = 0.026). Transthyretin and the RBP4:transthyretin molar ratio were comparable between the groups. Serum retinol was lower (p < 0.001) and the RBP4 Western blot level: retinol molar ratio was higher in women with gestational diabetes (p = 0.044). RBP4 was not associated with the glucose or homeostasis model assessment of insulin resistance (HOMA-IR), but in gestational diabetes the RBP4:retinol molar ratio correlated with blood glucose and negatively with 2 h post-load insulin. The RBP4:transthyretin ratio correlated with HOMA-IR and fasting insulin in controls. In women with gestational diabetes RBP4 EIA and western blot levels increased after delivery. Retinol increased in both groups, while transthyretin and the RBP4:transthyretin ratio were not altered after parturition.

CONCLUSIONS/INTERPRETATION

RBP4 measured by two different techniques is not elevated, but the RBP4:retinol molar ratio is higher and correlates with fasting blood glucose in women with gestational diabetes. Thus, the RBP4:retinol ratio and the RBP4:transthyretin ratio are more informative than RBP4 levels alone when assessing insulin-glucose homeostasis during pregnancy.

Serum concentrations of retinol-binding protein 4 in women with and without gestational diabetes

AIMS/HYPOTHESIS

Pregnancy is characterised by temporarily increased insulin resistance. Gestational diabetes occurs when pancreatic beta cell function is unable to compensate for this insulin resistance. Retinol-binding protein 4 (RBP4) could be related to insulin resistance. We hypothesised that RBP4 is elevated in gestational diabetes.

METHODS

Serum RBP4, transthyretin and retinol were cross-sectionally measured in 42 women with gestational diabetes and 45 pregnant controls. Of these, 20 women with and 22 without gestational diabetes were included in an additional longitudinal study. RBP4 was determined by enzyme immunometric assay (EIA) and western blot.

RESULTS

Women with gestational diabetes had lower RBP4 EIA and western blot levels than controls (median 6.8 [interquartile range, 3.9-14.3] vs 11.3 [7.8-19.9] microg/ml, p < 0.001 and 25.1 [21.7-29.6] vs 26.6 [23.5-32.2] microg/ml, p = 0.026). Transthyretin and the RBP4:transthyretin molar ratio were comparable between the groups. Serum retinol was lower (p < 0.001) and the RBP4 Western blot level: retinol molar ratio was higher in women with gestational diabetes (p = 0.044). RBP4 was not associated with the glucose or homeostasis model assessment of insulin resistance (HOMA-IR), but in gestational diabetes the RBP4:retinol molar ratio correlated with blood glucose and negatively with 2 h post-load insulin. The RBP4:transthyretin ratio correlated with HOMA-IR and fasting insulin in controls. In women with gestational diabetes RBP4 EIA and western blot levels increased after delivery. Retinol increased in both groups, while transthyretin and the RBP4:transthyretin ratio were not altered after parturition.

CONCLUSIONS/INTERPRETATION

RBP4 measured by two different techniques is not elevated, but the RBP4:retinol molar ratio is higher and correlates with fasting blood glucose in women with gestational diabetes. Thus, the RBP4:retinol ratio and the RBP4:transthyretin ratio are more informative than RBP4 levels alone when assessing insulin-glucose homeostasis during pregnancy.

A Study of Information Seeking by Cancer Patients and their Carers

AIMS

To examine cancer patients' and carers' use of, and attitudes to, the Internet as an information source compared with other media.

MATERIALS AND METHODS

The study was carried out in two phases: in phase I, interviews were used to construct a suitable instrument. In phase II, interviews were completed with 800 recently diagnosed patients and 200 carers.

RESULTS

Relatively few patients (4.8%), but a high proportion of carers (48%), accessed the Internet directly for cancer information. However, around half of the patients used Internet information provided by someone else, generally a family member. The use of Internet information was uniformly low among ethnic minorities. Those who accessed Internet information reported high levels of satisfaction and generally rated it higher than booklets or leaflets. When asked who they would like to provide Internet information, overwhelmingly patients wanted the hospital doctor to do so. When this was done, there was very high compliance. Carers were much more proactive information seekers than patients.

CONCLUSIONS

The Internet is an effective means of information provision in those who use it. Facilitated Internet access and directed use by health professionals would be effective ways of broadening access to this medium.

Visual outcomes following ICG assisted ILM peel for Macular Hole

PURPOSE

To evaluate the anatomical and visual outcome of indocyanine green (ICG)-assisted internal limiting membrane (ILM) peeling for macular hole surgery. A literature search identified potential factors that may affect the functional success of the procedure.

METHODS

Retrospective case note review of 14 consecutive patients undergoing phaco-vitrectomy, gas and ICG-assisted ILM peeling for macular hole from July 2001 to July 2002. A 0.5% ICG solution (osmolarity 270 mOsm) was left in contact with the retina for 1-3 min. The outcome measures were hole closure, change in visual acuity, and macular pigmentary changes.

RESULTS

Anatomical hole closure was achieved in 13 of 14 eyes (92.8%). The mean logMAR Snellen acuities were 0.80 (range 0.60-1.30) preoperatively and 0.77 (0.48-1.30) postoperatively. Seven eyes (50%) developed retinal pigmentary changes in the macular area.

CONCLUSIONS

ICG-assisted ILM peeling for macular hole surgery achieves high rates of anatomical hole closure, but functional results are less encouraging. Previous studies suggest toxicity of the ICG to the retina, at the level of the RPE or inner retina. The results may be optimized by using a lower concentration, iso-osmolar, viscous solution, and by minimizing contact time of the solution and intensity, and duration of illumination.

Sub-Tenon's block reduces both intraoperative and postoperative analgesia requirement in vitreo-retinal surgery under general anaesthesia

BACKGROUND AND OBJECTIVE

We compared the effects of sub-Tenon's local anaesthetic block and placebo on peri-operative opioid requirement and cardiovascular stability and on postoperative pain, nausea and vomiting in patients undergoing vitreo-retinal surgery under general anaesthesia.

METHODS

We studied 43 patients undergoing vitreo-retinal surgery under general anaesthesia in a randomized double blind study. Patients received a standard general anaesthetic followed by a sub-Tenon's injection of 4-5 mL of either bupivacaine 0.75% or saline. We recorded intraoperative invasive arterial pressure, then the incidence and severity of pain and of nausea and vomiting, for 24 h postoperatively.

RESULTS

In the sub-Tenon's bupivacaine group, there was a significant reduction in the perioperative opioid use and a reduction in the frequency of bradycardia and hypertensive episodes, defined as a rise > 25% of baseline for a duration of > 3 min. The sub-Tenon's bupivacaine group also had significantly lower pain scores and nausea scores at 12 h, concomitant with a lower consumption of analgesia and antiemetics.

CONCLUSIONS

This local anaesthetic technique is effective in vitreo-retinal surgery and can be safely applied to this population of patients regardless of axial length.

A new grading system for assessing orbicularis muscle function

PURPOSE

To establish an objective parameter (orbicularis function) to measure the efficacy of botulinum toxin treatment in weakening the orbicularis of blepharospasm and hemifacial spasm sufferers.

METHODS

The following scale has been used by one of the authors (VTT) in his botulinum clinic for several years: Grade 0: Incomplete eyelid closure.Grade 1: Lids just closing, minimal resistance to overcome.Grade 2: Closing well, some resistance, easily overcome.Grade 3: Strong closure, can be overcome with difficulty.Grade 4: Very strong closure, cannot be overcome or overcome with extreme difficulty. In order to establish the interobserver agreement, one consultant ophthalmologist, three ophthalmologists in training, and one nurse practitioner evaluated the same 65 patients, undergoing treatment with botulinum toxin for essential blepharospasm and hemifacial spasm. Observers assessed orbicularis function by asking each patient to close both eyes forcefully, while the observer tried to open them manually. The measure of agreement across the observers was estimated by kappa statistics.

RESULTS

Overall interobserver agreement (kappa=0.54) was satisfactory. We used Kruskal-Wallis nonparametric test to determine agreement between the observers. The P-values for both right and left eyes were well above 0.05, indicating good consistency between the observers when using this grading system.

CONCLUSIONS

A simple, new, five-point, clinical grading system for orbicularis muscle function is presented. Medical staff with different levels of experience can use it reliably.

Bleb-limiting conjunctivoplasty for symptomatic circumferential trabeculectomy blebs

PURPOSE

To describe a new surgical technique for limiting symptomatic circumferential conjunctival blebs, an uncommon complication after trabeculectomy.

METHODS

Four eyes of 2 patients underwent conjunctivoplasty to limit the extent of symptomatic circumferential blebs. An 8/0 virgin silk corneal traction suture was used to allow better exposure of the conjunctiva. Radial conjunctival and Tenon incisions were made down to bare sclera in approximately the 10:30 and 1:30 clock hour positions. The conjunctival incisions were sutured, tacking down to the sclera.

RESULTS

Immediate flattening of the interpalpebral bulbar conjunctiva was noted on the first postoperative day and there was no elevation of intraocular pressure or loss of bleb function. Both patients experienced a rapid improvement in their symptoms and no complications of the procedure were noted. Recurrence of bleb extension occurred in 1 eye 4 months postoperatively, and was treated with a repeat limiting conjunctivoplasty incision with a good result.

CONCLUSIONS

Early results show that bleb-limiting conjunctivoplasty is an effective means of treating symptomatic circumferential trabeculectomy blebs.