Nanocomposites of C3N4 with Layers of MoS2 and Nitrogenated RGO, Obtained by Covalent Cross-Linking: Synthesis, Characterization, and HER Activity.

Generation of hydrogen by photochemical, electrochemical, and other means is a vital area of research today, and a variety of materials have been explored as catalysts for this purpose. C3N4, MoS2, and nitrogenated RGO (NRGO) are some of the important catalytic materials investigated for the hydrogen evolution reaction (HER) reaction, but the observed catalytic activities are somewhat marginal. Prompted by preliminary reports that covalent cross-linking of 2D materials to generate heteroassemblies or nanocomposites may have beneficial effect on the catalytic activity, we have synthesized nanocomposites wherein C3N4 is covalently bonded to MoS2 or NRGO nanosheets. The photochemical HER activity of the C3N4-MoS2 nanocomposite is found to be remarkable with an activity of 12778 µmol h-1 g-1 and a turnover frequency of 2.35 h-1. The physical mixture of C3N4 and MoS2, on the other hand, does not exhibit notable catalytic activity. Encouraged by this result, we have studied electrochemical HER activity of these composites as well. C3N4-MoS2 shows superior activity relative to a physical mixture of MoS2 and C3N4. Density functional theory calculations have been carried out to understand the HER activity of the nanocomposites. Charge-transfer between the components and greater planarity of cross-linked layers are important causes of the superior catalytic activity of the nanocomposites. Covalent linking of such 2D materials appears to be a worthwhile strategy for catalysis and other applications.

Staphylococcus Aureus: Methicillin Resistance and Small Colony Variants from Pyogenic Infections of Skin, Soft Tissue and Bone.

BACKGROUND: Staphylococcus aureus (S. aureus) colonizing the nares, is the leading cause of hospital as well as community acquired infections. The aim of this study was to identify the S. aureus from skin, soft tissue and bone related infections and typing them on the basis of antimicrobial susceptibility profile. METHODS: Clinical samples were collected from patients with skin, soft tissue and bone related infections from January to October 2013 at Chitwan Medical College Teaching Hospital, Bharatpur. The S. aureus, small colony variants and methicillin resistant strains were identified by standard microbiological methods recommended by American Society for Microbiology. Antimicrobial susceptibility testing was performed by modified Kirby-Bauer disk diffusion method. RESULTS: Among 333 samples processed, there was positive growth of S. aureus in 66 (19.8%) samples. Among the isolated S. aureus, 10 isolates were small colony variants of S. aureus and all the strains recovered were thymidine independent in this study. Amikacin, vancomycin and teicoplanin were found to be the most effective antibiotics. Methicillin resistance was found in 34.8% isolates of S. aureus. CONCLUSIONS: It can be concluded that, S. aureus is one of the causative agent of pyogenic infections and the trend of antibiotic resistant is alarmingly high and also the rate of methicillin resistant S. aureus is comparably high in this study.

A game theoretical analysis of the mating sign behavior in the honey bee.

Queens of the honey bee, Apis mellifera (L.), exhibit extreme polyandry, mating with up to 45 different males (drones). This increases the genetic diversity of their colonies, and consequently their fitness. After copulation, drones leave a mating sign in the genital opening of the queen which has been shown to promote additional mating of the queen. On one hand, this signing behavior is beneficial for the drone because it increases the genetic diversity of the resulting colony that is to perpetuate his genes. On the other hand, it decreases the proportion of the drone's personal offspring among colony members which is reducing drone fitness. We analyze the adaptiveness and evolutionary stability of this drone's behavior with a game-theoretical model. We find that theoretically both the strategy of leaving a mating sign and the strategy of not leaving a mating sign can be evolutionary stable, depending on natural parameters. However, the signing strategy is not favored for most scenarios, including the cases that are biologically plausible in reference to empirical data. We conclude that leaving a sign is not in the interest of the drone unless it serves biological functions other than increasing subsequent queen mating chances. Nevertheless, our analysis can also explain the prevalence of such a behavior of honey bee drones by a very low evolutionary pressure for an invasion of the nonsigning strategy.

Common behaviour problems amongst primary school children in slum dwelling area of Kathmandu Valley.

A cross sectional observation study was carried out in primary school children of slum dwelling area of Kathmandu Valley which included 454 students. The aim of study was to find out morbidity in habit disorders in age group of 6-10 years so that early detection will be helpful to correct them to prevent it from further personality maladjustment. There was no statistical difference in gender wise habit disorders. The morbidity is due to multiple factors of physico- social environment. However severity of disease is not more here in this area.

Prevalence and determinants of diabetes among the elderly population in the Kathmandu Valley of Nepal.

Elderly populations are susceptible to many non-communicable diseases, including diabetes. Lack of awareness regarding disease status and risk factors increase complications and mortality. We conducted a cross-sectional community-based study of 1633 randomly selected participants aged 60 years and above in urban and rural areas in the Kathmandu Valley of Nepal. Study goals were: (i) to determine the prevalence of diabetes in elderly subjects as diagnosed prior to and during the study, and (ii) to identify and compare the determinants of diabetes as diagnosed prior to and during the study. A structured questionnaire was used to collect information regarding prevalence and potential determinants of diabetes diagnosed during and before the survey. Anthropometric measurements, blood pressure measurements and fasting blood sugar tests were also measured. Risk factor analysis was done using multinomial logistic regression; subjects with no diabetes constituted the reference group. We detected an overall diabetes prevalence of 25.9%, 17.3% diagnosed during the survey and 8.6% previously diagnosed. Age, disturbed sleep, and family history of hypertension were marginally significantly (p < 0.10) associated with diabetes diagnosed in the survey. In contrast, education, exercise, health perception, family history of hypertension, having a caretaker at night, receiving help from friends when seeking health care and mean waist circumference were significantly (p pounds 0.05) or marginally associated with diabetes detected before the survey. The high prevalence of diabetes in the elderly population studied, and the low level of prior diagnosis, identify an important public health problem. There is a need for improved screening of diabetes and improved health care and education in the elderly. There is also need for better understanding of risk factors associated with previously undiagnosed diabetes.

Multidrug-resistant nosocomial Citrobacter in a hospital in Kathmandu.

Citrobacter sp. is a commensal flora and an infrequent nosocomial pathogen to cause nuisance in hospital settings. Recently, the isolation of this pathogen in health care setting is rising and the multidrug resistant strains are emerging. This pathogen cause wide array of infections and the mortality rate is unexpectedly high of 30.0-60.0%. Extended spectrum cephalosporins have been used to treat this pathogen and due to the emergence of resistant strains to these drugs newer treatment protocols have to be devised. Epidemiology and antibiotic susceptibility pattern of clinical isolates of Citrobacter sp. isolated in a hospital were investigated. Specimens were collected from patients and implicated pathogens were isolated. Disk diffusion test was performed on these isolates and resistant patterns were. Antibiogram typing was used to resolve the clones of the isolated bacteria. The results showed that Citrobacter sp. was highly prevalent and commonly isolated from the sputum sample of patients diagnosed as Chronic Obstructive Pulmonary Disease (COPD). The antibiogram pattern suggested the circulation of three clones of Citrobacter sp. They were multidrug resistant and were sensitive to only cefoperazone and sulbactam suggesting the production of â-lactamse inhibitors sensitive molecular class A and D extended spectrum â-lactamases (ESBL). In conclusion, although, ESBL producers are always treated with carbapenems, we recommend to use combination therapy of â-lactam and â-lactamse inhibitors to treat this multidrug resistant Citrobacter sp. and carbapenems should be kept as a reserve drug and we should aim to prevent the spread of this resistant pathogen between different patients to decrease the morbidity and mortality associated with this pathogen.

Human fetal adrenal transplant: a possible role in relieving intractable pain in advanced rheumatoid arthritis.

BACKGROUND: The art of transplant surgery has gone a long way in establishing itself as an important discipline in medicine with the support of molecular biology, immunology, biochemistry, etc., as the ultimate treatment for the restoration of function of a failing organ. With the progressive increase in the life expectancy of human beings, there is an increasing discrepancy in the demand and supply of organ grafts. A less efficient alternative could be synthetic or mechanical grafts. Nucleated cell therapy, that is, cellular transplant, is a promising new area of study with its proven efficacy in neuro-degenerative disorders, hematopoietic disorders, diabetes and trauma-induced tissue loss, to name a few. Human fetal cell/tissue with its intrinsic hypo-antigenic advantage (up to 20 weeks of study), could be an interesting area of cellular/tissue transplant. Our research group has earlier reported on the safe use of umbilical cord whole blood and the successful transplant of a human fetal lung, heart, pancreas, liver, thymus, in an artificially prepared vascular subcutaneous axillary fold in which there was no feature of hyper-acute, acute or chronic rejection of the graft in HLA- and sex-randomized adult recipients, without concomitant immunosuppressives or radiation of the host to potentiate the survival of the fetal graft (within 20 weeks of gestation) within the lowest observation period of one month. The present study was aimed at examining the role of developing fetal adrenal transplants for patients with rheumatoid arthritis and severe pain due to involvement of inflammatory and neuropathic components. MATERIALS AND METHOD: Ten cases were enrolled in the present study after thorough informed consent and approval by the ethical committee of the institute. The age of the patients varied from 50 to 76 years and the group was comprised of three males and seven females. The age of the adrenal grafts varied from 16 to 20 weeks and these were collected from mothers admitted for hysterotomy and ligation. These long-standing rheumatoid patients (suffering for five to 15 years), presented with at least four of the seven 1987 revised criteria of the American College of Rheumatology for diagnosis of rheumatoid arthritis. A 2.5 cm long and 2 cm deep tissue space was dissected and prepared in each transplant recipient at the axilla using diathermy and knife after infiltrating the site with one percent lignocaine solution. The tissue collected from the consenting mother undergoing hysterotomy and ligation was inserted into this site, and the site was closed with 00 atraumatic vicryl. All necessary pre- and postoperative surgical precautions were taken to prevent infections. Sequential total count and differential count of leucocytes were undertaken to analyze the impact of the transplant on the host. After one month, a part of the transplanted fetal tissue was recovered for histological staining to examine whether there was any graft versus host reaction. RESULTS AND ANALYSIS: All ten patients tolerated the transplant procedure well. There was no fever, intractable pain or any other specific serious side-effect which could justify the removal of the transplant before one month. There was no discharge from the incision site and the healing of the scar was by and large normal. There was no unusual leucocytosis, lymphocytosis and the retrieved graft tissue did not suggest transplant rejection. However, there was definite pain relief, reduction in swelling and improvement of mobility of varying degree in a majority of the patients which was perceivable from the 15th day onwards. There was also a sense of well being (in 80%) and a gain in weight of three pounds or more (in 70%) among the fetal transplant recipients. DISCUSSION AND CONCLUSION: To understand the underlying mechanism, in case of pregnancy immunotolerance, we are of the opinion that emphasis should be placed on the role of non-specific and non-cytopathic blocking antibodies produced during pregnancy. The hypo-antigenicity of the developing human fetal system may possibly contribute to the production of this blocking antibody during pregnancy, and thus may play a role in the lack of recognition by the host's HLA system. This behaviour of the developing human fetal tissue provides some advantages over adult tissue for fetal cell/tissue transplantation purposes. The relief of pain, inflammation and restoration of mobility may be due to the effect of the transplanted adrenal graft, with the medullary component contributing to endorphin-like substance liberation and the cortical component contributing to glucocorticoid synthesis.

Can human fetal cortical brain tissue transplant (up to 20 weeks) sustain its metabolic and oxygen requirements in a heterotopic site outside the brain? A study of 12 volunteers with Parkinson's disease.

BACKGROUND: Neural and stem cell transplantation is emerging as a potential treatment for neurodegenerative diseases from Parkinson's to Huntington's disease. Stereotactic placement of dopaminergic neurons in the caudate-putamen (striatum), is being attempted in centers of excellence and has proved to be beneficial. Basic research using cell transplantation indicates that structural development mechanisms seen in immature brains, i.e., fetal brains, can also function in the adult brain. The adult brain consumes 15% of the resting cardiac output for its metabolic needs. While most human tissues can sustain an anaerobic assault for a few minutes up to 30 minutes, a sudden total lack of oxygen supply to the brain cells in an adult will render the person unconscious within five to ten seconds. Our team has been working on the problem of human fetal tissue response to antigenic assault for the last two decades. In the present series, 12 patients with prolonged histories of Parkinsonism, who were not responding to anti-Parkinsonian drugs, and could not afford costly stereotactic surgery or deep brain stimulation and other modalities of recent Parkinson's disease treatment, were enrolled in the study. MATERIALS AND METHOD: After obtaining proper informed consents from the patients or their guardians and from the multidisciplinary ethical committee, the patients, varying in age from 45 to 75 years and suffering for many years with Parkinsonism, were enrolled in the heterotopic brain tissue transplant programme. We followed standard antiseptic, aseptic and premedication protocols, after selecting a proposed site of transplantation of the brain in the axillary fold of the skin, under local infiltration anaesthesia. In an adjacent OR, a fetus was collected from a consenting patient undergoing hysterotomy and ligation (before 20 weeks), under general anaesthesia. Within a minute of hysterotomy, the fetal brain tissue was dissected, and under the guidance of the operative microscope, 1 g of fetal cortical brain tissue was dissected and weighed in an electronic machine. The tissue was collected from around 1 cm of the frontal opercula of the developing human fetal brain and grafted in the already dissected and prepared subcutaneous site in the axilla and the skin was closed. Hematological parameters (Hgb; total count, Tc; differential count, Dc; erythocyte sedimentation rate, ESR) were estimated sequentially up to one month. A small portion of the transplanted tissue was retrieved after one to two months, and a serial histological study was done along with a clinical assessment of the disease condition as per the specifications of the Unified Parkinson's Disease Rating Scale. The results were matched with the pre-transplant ratings of the individual cases. Presenting dyskinesia was also rated (0-4), on the basis of objective criteria assessment like walking, putting on a coat, lifting a cup to drink, etc. RESULTS AND ANALYSIS: Initially 30 patients suffering from advanced Parkinson's disease (PD) were approached after getting the necessary clearance from the institutional multidisciplinary ethical committee; however, we have been able to arrange transplantation in only 12 cases so far. These patients were evaluated at the pre- and one month post-transplant period by the Unified Parkinson's Disease Rating Scale (0-108) and the minimum score was 40 in the motor portion of the unified scale at the pre-transplant state. Evaluation of the patients after one month revealed mild improvement of the pre-transplant scoring (up to 33.3%) in 41.6% of the cases, and moderate improvement (up to 66.6%) in another 41.6% of the cases. While 16.8% of the cases did not show any improvement from the basal score, i.e., the pre-transplant score, there was a definite sense of well being and rise in weight (2-4 pounds) noted in each case and there was also a reduction of the L-Dopa dosage in 75% of the cases. There was also a 58.3% improvement in the bradykinesia scoring from the pre-transplant level. What is intriguing is the survival, growth and proliferation of the grafted fetal brain tissue in the HLA- and sex-randomized adult axilla without any immunosuppressive support. Not a single histological study of the fetal brain tissues after removal from the axilla showed any signs of graft vs. host or inflammatory reaction (Figures 1-9) but there were features of growth of the transplanted cortical brain tissue along with its different components like neurogenesis, gliogenesis, early neovascularisation and angiogenesis, etc. There was also no systemic leucocytosis or lymphocytosis. DISCUSSION AND CONCLUSION: Histological evidence at the transplanted tissue site suggests that fetal cortical brain tissue can sustain life in sex-randomized, HLA-randomized adult hosts, without the support of immuno-suppressive drugs and the tacit support of the blood-CSF and blood-brain barrier and other specific requirements of adult brain cells in the skull. Whether the clinical improvement in PD is transient or long lasting is presently under investigation along with basic questions like, is it due to transplanted fetal dopaminergic or non-dopaminergic neurons or is it the growth factors and the cytokine mediated hitherto unknown reactions causing the clinical improvement.

Cardiac involvement in non-specific aorto-arteritis.

Cardiac involvement in 75 cases (mean age 21.1 +/- 6 years) with non-specific aorto-arteritis was studied. Detailed clinical examination, echocardiography and cardiac catheterization, including angiography, were done in all the cases, as was coronary angiography. Features of cardiac failure like sinus tachycardia, cardiomegaly, left ventricular third heart sound gallop and pulmonary congestion were detected in 27 cases with reduction of left ventricular ejection fraction (25-48%). Systemic hypertension was seen in 60 cases. Central aortic pressure, left ventricular systolic pressure and left ventricular end-diastolic pressure were increased in 66 cases. Pulmonary hypertension and increased pulmonary vascular resistance were detected in 6 cases. Aortic and mitral regurgitation were seen in 15 and 12 cases, respectively. Three patients had features of dilated cardiomyopathy such as generalized cardiomegaly, systemic and pulmonary congestion but without any cardiac murmurs and with normal central aortic pressure. The coronary angiogram revealed obstruction of the left anterior descending artery in 3 cases and right coronary artery obstruction in another 3 cases. Histopathological studies revealed non-specific inflammatory changes with fibrosis in cardiac musculature and the great vessels.

Cardiac changes implicated in chronic heart block.

Fifteen cases of chronic heart block were studied. Eight of them could be designated as idiopathic or primary heart block; the others were associated with hypertension, diabetes and ischaemic heart disease, either singly or in various combinations. In six cases, the whole heart was available for histopathological study of the conduction system. In the other 9 cases, only a portion of the heart muscle was available for examination. A V nodal fibrosis extending upto the proximal bundle of His was seen in all the six whole heart autopsy materials. Fibrosis of the adjacent myocardium was seen in five cases. In three cases, conducting system fibrosis was associated with atherosclerotic (1 case) or diabetic changes (3 cases) of the intramural vessels. In the 9 partial autopsy studies, myocardial fibrosis was seen in two cases, diabetic microangiopathy in one and atherosclerotic changes in two including an old thrombus in one. Thus, diabetic microangiopathy was seen in total four cases. These changes may be responsible for the cardiomegaly and cardiac failure associated with conduction defects observed in diabetes. In the idiopathic group also, heart block could be considered as a significant facet of a primary myocardial degenerative process.

An unusual extension of pericardial effusion in a case of pulmonary adenocarcinoma.

A case of pericardial metastasis from adenocarcinoma of lung was having a separate paratracheal bulge at left border of aorta mimicking a tumour. This was a very uncommon extension of pericardial effusion. Interestingly this mediastinal bulge on left border of aorta disappeared completely immediately after pericardio-centesis. The rarity of chest roentgenographic findings prompted us to report this case.