Supersaturated Calcium Phosphate Rinse in Prevention and Treatment of Mucositis in Patients Undergoing Hematopoietic Stem Cell Transplant

OBJECTIVES

Mucositis is a common morbidity in patients undergoing bone marrow transplant. Various agents have been used to prevent and treat it with variable success. Here, we assessed the efficacy of supersaturated calcium phosphate rinses in prevention and treatment of oral mucositis in patients undergoing hematopoietic stem cell transplant.

MATERIALS AND METHODS

In this retrospective study, we evaluated the records of 80 patients who underwent hematopoietic stem cell transplant and received supersaturated calcium phosphate rinses for preVention of mucositis from April 2012 to January 2016. The World Health Organization scale was used to grade mucositis. Various parameters assessed included grade of mucositis, duration of mucositis, peak mucositis day, duration of pain, peak pain day, duration of total parenteral nutrition, neutrophil engraftment (defined as absolute neutrophil count ≥ 500/μL), mean dose of fentanyl used, incidences of infections, and type of transplant. Supersaturated calcium phosphate rinses at 4 times/day were started for prevention of mucositis as soon as a patient was admitted. All patients also received betadine mouth gargles for oral hygiene.

RESULTS

Our study group included 42 autologous and 38 allogeneic hematopoietic stem cell transplant patients. Grade 1, 2, 3, and 4 mucositis levels were seen in 1, 19, 26, and 31 patients. We found no differences between our study group and historical control regarding parameters studied. Grade of mucositis was statistically significant (P < .01) when autologous transplant for myeloma was compared with autologous transplant for other diagnoses.

CONCLUSIONS

Supersaturated calcium phosphate rinses were ineffective in the management of mucositis associated with autologous and allogeneic bone marrow transplant.

Anti-HSV-2 activity of Terminalia chebula Retz extract and its constituents, chebulagic and chebulinic acids

Background

Development of new and effective therapeutics for sexually transmitted herpes simplex virus-2 (HSV-2) infection is important from public health perspective. With an aim to identify natural products from medicinal plants, in the present study, the potential of Terminalia chebula Retz was investigated for its activity against HSV-2.

Methods

Fruits of Terminalia chebula Retz were used to prepare 50% ethanolic extract. In addition, chebulagic acid and chebulinic acid both purified from T. chebula were also used. The extract as well as purified compounds were first used to determine their in vitro cytotoxicity on Vero cells by MTT assay. T. chebula extract, chebulagic acid, chebulinic acid along with acyclovir were subsequently assessed for direct anti-viral activity, and their ability to inhibit attachment and penetration of HSV-2 to the Vero cells. In addition, their anti-HSV-2 activity was also determined by in vitro post-infection plaque reduction assay.

Results

Cytotoxicity assay using Vero cells revealed CC₅₀ = 409.71 ± 47.70 μg/ml for the extract whereas chebulagic acid and chebulinic acid showed more than 95% cell viability up to 200 μg/ml. The extract from T. chebula (IC₅₀ = 0.01 ± 0.0002 μg/ml), chebulagic (IC₅₀ = 1.41 ± 0.51 μg/ml) and chebulinic acids (IC₅₀ = 0.06 ± 0.002 μg/ml) showed dose dependent potent in vitro direct anti-viral activity against HSV-2. These also effectively prevented the attachment as well as penetration of the HSV-2 to Vero cells. In comparison, acyclovir showed poor direct anti-viral activity and failed to significantly (p > 0.05) prevent the attachment as well as penetration of HSV-2 to Vero cells when tested upto 50 μg/ml. However, in post-infection plaque reduction assay, T. chebula extract, chebulagic and chebulinic acids showed IC₅₀ values of 50.06 ± 6.12, 31.84 ± 2.64, and 8.69 ± 2.09 μg/ml, respectively, which were much lower than acyclovir (71.80 ± 19.95 ng/ml).

Conclusions

The results presented herein suggest that T. chebula extract, chebulagic and chebulinic acids have higher direct antiviral activity against HSV-2 and efficacy to inhibit virus attachment and penetration to the host cells as compared to acyclovir. However, acyclovir is more potent to inhibit post-infection virus replication. Hence, T. chebula may be a useful candidate for developing alternative therapy for prevention of sexually transmitted HSV-2 infection.

Graphical abstract

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Cellular stress and histopathological tools used as biomarkers in Oreochromis mossambicus for assessing metal contamination

In the present study, we have analyzed various biochemical and histopathological biomarkers in the Oreochromis mossambicus collected from 18 sites at Bhima River. The biochemical biomarkers viz. antioxidative enzymes in muscle viz. catalase, SOD, and GST, glycolytic enzymes in kidney viz. LDH and MDH, protein metabolic enzymes in liver, gill, brain, gonad and muscle viz. ALT and AST, neurotransmitter enzymes in muscle AChE, lipid peroxidation and histopathology in the liver and gill have been evaluated. The oxidative biomarkers, glycolytic enzymes, protein metabolic enzymes and lipid peroxidation were significantly (p<0.01) higher and AChE in muscle were significantly inhibited (p<0.01) in fishes from different sampling sites. The histopathology of the liver and gill were altered at different sampling sites. The liver histopathology showed hepatocytes vacuolization, haemorrhage, karyokinesis, necrosis, pyknotic nuclei, dilation of sinusoids and hepatocyte granular degeneration and in the gill histopathology showed distal lamellar gill tissue, diffuse epithelial hyperplasia and multifocal mucus cell hyperplasia, extensive edema of epithelial cells, blood congestion and edema in secondary lamellae. All the indicators are giving strong signals for contamination of the aquatic water bodies. The Bhima River is surrounded by several cities and agriculture land indicates that vigorous industrial activity coupled with intensive use of chemicals in agricultural practices may held. Therefore, based on our results, we could recommend that the investigated tissue and cell alterations may be successfully applied as reliable biomarkers for monitoring contaminated freshwater ecosystems. This study suggests that, the importance of antioxidative enzymes, cellular biomarkers, AChE, and histopathology used as biomarkers in aquatic ecosystem biomonitoring.

Generation and characterisation of monoclonal antibodies specific to avian influenza H7N9 haemagglutinin protein

INTRODUCTION

Emerging virulent strains of influenza virus pose a serious public health threat with potential pandemic consequences. A novel avian influenza virus, H7N9, breached the species barrier from infected domestic poultry to humans in 2013 in China. Since then, it has caused numerous infections in humans with a close contact to poultry.

MATERIALS AND METHODS

In this study, we describe the preliminary characterisation of five murine monoclonal antibodies (MAbs) developed against recombinant haemagglutinin (rHA) protein of avian H7N9 A/Anhui/1/2013 virus by their Western blot and enzyme-linked immunosorbent assay (ELISA) reactivity and binding affinity.

RESULTS

Of the five MAbs, four were highly specific to H7N9 HA and did not show any cross-reactivity in ELISA with rHA protein from pandemic as well as seasonal H1N1, H2N2, H3N2, H5N1 and influenza virus B (B/Brisbane/60/2008). However, one of the MAbs, MA-24, in addition to HA protein of H7N9 also reacted strongly with HA protein of H3N2 and weakly with HA of pandemic and seasonal H1N1 and H2N2. All the five MAbs also reacted with H7N9 rHA in Western blot. The MAbs bound H7N9 rHA with an equilibrium dissociation constant (KD) ranging between 0.14 and 25.20 nM, indicating their high affinity to HA.

CONCLUSIONS

These antibodies may be useful in developing diagnostic tools for the detection of influenza H7N9 virus infections.

Survival and failure patterns in atypical and anaplastic meningiomas: A single-center experience of surgery and postoperative radiotherapy

INTRODUCTION

Intracranial meningiomas are the second most common tumor of the CNS. The high-grade tumors are atypical and malignant meningioma comprising 5-7% and 1-3% of all meningiomas. The high-grade meningioma have an aggressive histopathological and clinical behavior.

MATERIALS AND METHODS

We retrospectively reviewed 37 patients of high-grade meningioma treated in our institute from 2002 to 2011. Clinical characteristics and treatment modality in form of surgery and radiotherapy (RT) were noted. Statistical analysis was done with regards to progression-free survival (PFS) and overall survival (OS) using Kaplan-Meier survival analysis.

RESULTS

The median age of the patients was 45.0 years. The median duration of symptoms was 6 months. Headache was the most common presenting symptom. Fourteen patients underwent complete excision, while 23 had subtotal excision. Twenty-two patients had World Health Organization (WHO) grade II histology tumors and 15 patients had grade III histology. Median RT dose delivered was 50 Gy for grade II tumors and 54 Gy for grade III tumors. Five-year PFS for grade II and III tumors was 58 and 20%, respectively. Five-year OS for grade II and III tumors was 83 and 23%, respectively.

CONCLUSIONS

High-grade meningiomas represent a rare and aggressive neoplasm. The mainstay of therapy is gross total resection (GTR) at the initial surgery. Postoperative adjuvant RT should be offered to all patients, regardless of the degree of resection achieved. Long-term follow-up is important as local recurrences and progression can develop years after the initial treatment.

Transient Weakening of Earth's Magnetic Shield Probed by a Cosmic Ray Burst

The GRAPES-3 tracking muon telescope in Ooty, India measures muon intensity at high cutoff rigidities (15-24 GV) along nine independent directions covering 2.3 sr. The arrival of a coronal mass ejection on 22 June 2015 18:40 UT had triggered a severe G4-class geomagnetic storm (storm). Starting 19:00 UT, the GRAPES-3 muon telescope recorded a 2 h high-energy (∼20  GeV) burst of galactic cosmic rays (GCRs) that was strongly correlated with a 40 nT surge in the interplanetary magnetic field (IMF). Simulations have shown that a large (17×) compression of the IMF to 680 nT, followed by reconnection with the geomagnetic field (GMF) leading to lower cutoff rigidities could generate this burst. Here, 680 nT represents a short-term change in GMF around Earth, averaged over 7 times its volume. The GCRs, due to lowering of cutoff rigidities, were deflected from Earth's day side by ∼210° in longitude, offering a natural explanation of its night-time detection by the GRAPES-3. The simultaneous occurrence of the burst in all nine directions suggests its origin close to Earth. It also indicates a transient weakening of Earth's magnetic shield, and may hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth, and endanger the lives of the astronauts in space.

Suicidal asphyxiation by carbon monoxide within a polythene bag

Suicide by inhalation of carbon monoxide is not uncommon and usually involves car exhausts or burning charcoal or defective boilers. We report a case of a 25-year-old man, who committed suicide by inhaling carbon monoxide gas inside a polythene bag in a bathroom. The open carbon monoxide cylinder found inside the polythene bag was purchased online by the deceased a few days earlier. He had stated that the gas would be used for his experiment on the environment. A suicide note recovered from his trouser pocket revealed his intention for a painless death.

Restriction site detection in repetitive nuclear DNA sequences of Trypanosoma evansi for strain differentiation among different isolates

The differences or similarities among different isolates of Trypanosoma evansi through endonuclease profile was identified in the present study. The repetitive nuclear DNA of T. evansi isolated from infected cattle, buffalo and equine blood was initially amplified by PCR using specific primers. A panel of restriction enzymes, EcoRI, Eco91l, HindIII and PstI were for complete digestion of PCR products. Agarose gel electrophoresis of digested product did not show cleavage fragments and only single DNA band of the original size was visible in the ethidium bromide stained agarose gel. This indicated that the 227 bp PCR product from repetitive sequence had no site-specific cleavage sites for the REs used in this study. No heterogeneity in the repetitive nuclear DNA restriction endonuclease profile among the different isolates was recorded.

Acute toxicity, biochemical and histopathological responses of endosulfan in Chanos chanos

This study investigated 96h median lethal concentration of endosulfan (99%, pure α: β ratio of 7:3) by conducting static non-renewable acute toxicity bio-assay in Chanos chanos juvenile with average weight (110±5.65g). Further, the effect of different definitive doses (18.5, 19.5, 20.5, 21.5 and 22.5µg/L) of endosulfan on metabolic, heamato-immunoligcal and histopathological response were probed. Anti-oxidative enzymes CAT, SOD and GST showed significant (p<0.01) increase of activity in the liver, gill and brain during exposure to endosulfan in a dose and time dependent manner. The brain AChE activity showed significant (p<0.01) inhibition from 18.5 to 22.5µg/L exposure of endosulfan than the control group. LDH and MDH activity gradually increased with consequent increasing dose of endosulfan exposure in the liver, gill and brain. Similarly, ALT, AST and G6PDH activities in both liver and gill increased with consequent increases in the dose of endosulfan exposure. Immunological profile such as blood glucose and serum cortisol level significantly enhanced while respiratory burst activity declined with consequent increasing doses of endosulfan exposure. Histopathological alteration in the gill demonstrated curling of secondary lamellae, thickening of primary epithelium, shorting of secondary lamellae, epithelial hyperplasia, fusion of secondary lamellae, aneurism, and collapsed secondary lamellae due to dose dependent exposure of endosulfan. Liver histology illustrated cloudy swelling and necrosis with pyknotic nuclei to the moderate dose of endosulfan, whereas higher dose of endosulfan (21.5µg/L) displayed severe necrosis of hepatic cells. Overall results clearly indicate that acute exposure of endosulfan led to pronounced deleterious alterations on biochemical, heamato-immunological, and histopathological responses of C. chanos juvenile.

Image-guided fine-needle aspiration cytology of deep-seated enlarged lymph nodes

Purpose: To evaluate the role of image-guided fine-needle aspiration cytology (FNAC) of deep-seated lymph nodes.

Material and Methods: Image-guided FNACs were performed on 242 patients of deep-seated lymph nodes which included thoracic, retroperitoneal and abdominal nodes. A sterile 3.5/5-MHz micro convex sector probe was used for localisation of the node. The FNAC was performed using a 0.7- to 0.9-mm needle with the stylet removed and attached to a 20-ml syringe and FNAC handle after the needle was visualised in the lesion. For each case a minimum of 4-5 smears were made, and two observers without bias interpreted the smears.

Results: A total of 242 patients were aspirated, of which 216 (90%) aspirations were US-guided and the remaining 26 (10%) were CT-guided. Adequate material for cytologic diagnosis was obtained in 208 (86%) patients with a similar diagnostic accuracy. The aspirate material was non-representative or scanty in 34 (14%) patients. The most common cytological diagnosis was tuberculosis/consistent with tuberculosis seen in 108 (45%) patients followed by metastasis (17%) and reactive hyperplasia (10%). Non-Hodgkin lymphoma was diagnosed in 22 (9%) patients. All patients were briefly followed for a period of 1 1/2 to 2 years (mean 1 year).

Conclusion: Image-guided FNAC has a pivotal role, and is a cost-effective tool for establishing tissue diagnosis as a primary investigative modality. It is also helpful and accurate in follow-up of patients with a known malignant disease, thereby avoiding surgical intervention.

Carotid Endarterectomy in Patients with Renal Insufficiency: Should Selection Criteria be Different in Patients with Renal Insufficiency?

The objective of this study was to elucidate the relationship between outcomes from carotid endarterectomy (CEA) in patients with and without renal insufficiency.

Carotid endarterectomy is one of the most commonly performed vascular procedures. The role of cardiac comorbidity in carotid endarterectomy has been extensively studied. The relationship between renal failure and surgical outcomes has also been studied for both coronary artery bypass grafting and lower extremity occlusive disease. However, the role of renal insufficiency in relationship to decision making regarding surgical intervention for carotid stenosis is not well defined. The authors hypothesized that the outcomes from CEA were negatively influenced by renal dysfunction. A retrospective review was made of consecutive CEAs performed at their institution from 1990 to 1995. Patients were grouped into 2 categories according to their renal function. Group A, 448 patients (90%) with creatinine level 1.8 mg/dL or less, and group B, 49 patients (10%) with creatinine levels more than 1.8 mg/dL. Data from patients on dialysis are presented but were excluded for the purpose of analysis.

Included in the study were 497 patients with a mean age of 70 +8.9 and 74 +8.9 for groups A and B, respectively. Preoperative creatinine was 1.1 (±0.25) mg/dL for group A and 2.5 (+0.81) mg/dL for group B. Outcomes were as follows: perioperative cardiac events 5.4% vs 28.6%, stroke rates 2.7% vs 2.0%, and mortality rates 0.9% vs 8.2%, for groups A and B, respectively. At 60-month follow-up the stroke rates were 7.6% vs 6.1%, and the mortality rates 22.8% vs 59.2%, for groups A and B, respectively.

While patients with chronic renal insufficiency have no increased risk of perioperative or long-term neurologic events, perioperative and long-term mortality rates are significantly increased. This significant reduction in survival should prompt a more cautious application of CEA in patients with increased creatinine.

Neutralization and Binding Profile of Monoclonal Antibodies Generated Against Influenza A H1N1 Viruses

Monoclonal antibodies (MAbs) provide scope for the development of better therapeutics and diagnostic tools. Herein, we describe the binding and neutralization profile(s) for a panel of murine MAbs generated against influenza A H1N1 viruses elicited by immunization with pandemic H1 recombinant hemagglutinin (rHA)/whole virus or seasonal H1 rHA. Neutralizing MAbs, MA-2070 and MA-M, were obtained after pandemic A/California/07/2009 (H1N1) virus/rHA immunization(s). Both MAbs reacted specifically with rHA from A/California/07/2009 and A/England/195/2009 in ELISA. MA-2070 bound rHA of A/California/07/2009 with high affinity (KD = 51.36 ± 9.20 nM) and exhibited potent in vitro neutralization (IC50 = 2.50 μg/mL). MA-2070 bound within the stem domain of HA. MA-M exhibited both hemagglutination inhibition (HI, 1.50 μg/mL) and in vitro neutralization (IC50 = 0.66 μg/mL) activity against the pandemic A/California/07/2009 virus and showed higher binding affinity (KD = 9.80 ± 0.67 nM) than MA-2070. MAb, MA-H generated against the seasonal A/Solomon Islands/03/2006 (H1N1) rHA binds within the head domain and bound the seasonal H1N1 (A/Solomon Islands/03/2006 and A/New Caledonia/20/1990) rHAs with high affinity (KD; 0.72-8.23 nM). MA-H showed high HI (2.50 μg/mL) and in vitro neutralization (IC50 = 2.61 μg/mL) activity against the A/Solomon Islands/03/2006 virus. All 3 MAbs failed to react in ELISA with rHA from various strains of H2N2, H3N2, H5N1, H7N9, and influenza virus B, suggesting their specificity for either pandemic or seasonal H1N1 influenza virus. The MAbs reported here may be useful in developing diagnostic assays.

Assessment of home hazards for childhood injuries in an urban population in New Delhi

BACKGROUND

Childhood injuries, especially the unintentional category of injuries, occur most commonly in the environment inside a child's home. The primary objective of the present study was to assess the presence of home hazards for childhood injuries in households in an urban resettlement colony in New Delhi.

METHODS

A community-based cross-sectional study was carried out in an urban resettlement colony in Delhi. A hazards assessment tool was used to check the presence of hazards in the houses.

RESULTS

A total of 225 households were included. It was seen that121 (53.7%) had a cooking stove within the reach of the child, and 190 (84.3%) had the gas pipe within reach. Fire hazard was seen in 84% of houses. About 78% of households did not have locked storage for chemicals.

CONCLUSION

The study revealed a significant burden of hazards for childhood injuries within their own homes, thus emphasizing the need for injury prevention interventions to reduce the number of hazards.

Medico-legal autopsy of abandoned foetuses and newborns in India

Foeticide and the abandonment of newborns are important, albeit frequently neglected, issues. Concealment of childbirth is often seen in the setting of unwanted pregnancy which has been recognised as one of the most important factors in both cases. This study highlights the medico-legal autopsy findings of 238 abandoned foetuses and newborns over a period of 17 years (1996-2012) from the region of South Delhi, India. There was no sex predilection. The majority of the cases were full term. Nearly 35% of the foetuses were still born, about 29% were live born and the remainder were non-viable. Among the live born, death by homicide was more common than a natural death and most were left by the roadside. The abandoning and killing of newborns needs urgent attention, and strict measures are needed to save thousands of innocent lives.

Development and gamma-scintigraphy study of Hibiscus rosasinensis polysaccharide-based microspheres for nasal drug delivery

OBJECTIVE

This work describes the application of natural plant polysaccharide as pharmaceutical mucoadhesive excipients in delivery systems to reduce the clearance rate through nasal cavity.

METHODS

Novel natural polysaccharide (Hibiscus rosasinensis)-based mucoadhesive microspheres were prepared by using emulsion crosslinking method for the delivery of rizatriptan benzoate (RB) through nasal route. Mucoadhesive microspheres were characterized for different parameters and nasal clearance of technetium-99m ((99m)Tc)-radiolabeled microspheres was determined by using gamma-scintigraphy.

RESULTS

Their Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies showed that the drug was stable during preparation of microspheres. Aerodynamic diameter of microspheres was in the range 13.23 ± 1.83-33.57 ± 3.69 µm. Change in drug and polysaccharide ratio influenced the mucoadhesion, encapsulation efficiency and in-vitro release property. Scintigraphs taken at regular interval indicate that control solution was cleared rapidly from nasal cavity, whereas microspheres showed slower clearance (p < 0.005) with half-life of 160 min.

CONCLUSION

Natural polysaccharide-based microspheres achieved extended residence by minimizing effect of mucociliary clearance with opportunity of sustained delivery for longer duration.

Sino-Nasal Status in Patients with Chronic Obstructive Pulmonary Disease

Background. Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease with serious impact on quality of life (QoL). There are limited studies available supporting coexistence of sino-nasal involvement in COPD. Methods. A prospective study was conducted to evaluate sino-nasal status in patients with COPD (n=100) presenting to the Department of Respiratory Medicine, Mahatma Gandhi Medical College and Hospital, Jaipur from July 2011 to October 2012. COPD was diagnosed based on the Global initiative on Obstructive Lung Disease (GOLD) guidelines. Sino-nasal status was assessed by detailed history, radiograph of the para-nasal sinuses (PNS), nasal endoscopy and mucociliary clearance time. Results. Sino-nasal symptoms were present in 74 patients with COPD; nasal discharge (75.7%) being the most common. Tobacco smokers with COPD had a higher occurrence of sino-nasal symptoms (76.8%). Radiograph of para-nasal sinuses showed that maxillary sinus was most commonly involved. Nasal endoscopy revealed discharge in 63.5% cases. Nasal mucociliary clearance time was delayed (>11 to >40 min) in 98% cases. Nasal mucociliary clearance time was significantly delayed (>20 min) in COPD patients who were tobacco smokers as compared to non-smokers (53.7% versus 16.7%) and also related with increasing severity of COPD. Conclusions. Our observations suggest that sino-nasal involvement and delayed mucociliary clearance are common in patients with COPD, especially in tobacco smokers. Assessment of upper airway involvement in all the patients with COPD can help better therapeutic intervention and improvement in QoL.

Contraceptive efficacy of recombinant fusion protein comprising zona pellucida glycoprotein-3 fragment and gonadotropin releasing hormone

Contraceptive vaccines have been used for the management of wildlife population. In the present study, we have examined the contraceptive potential of Escherichia coli-expressed recombinant fusion protein comprising of 'promiscuous' T cell epitope of tetanus toxoid [TT; amino acid (aa) residues 830-844] followed by dilysine linker (KK), dog ZP3 fragment (aa residues 307-346), triglycine spacer (GGG), T cell epitope of bovine RNase (bRNase; aa residues 94-104), GnRH, T cell epitope of circumsporozoite protein of Plasmodium falciparum (CSP; aa residues 362-383), and GnRH. SDS-PAGE analysis of the purified refolded protein revealed a dominant ∼12 kDa band, which in Western blot reacted with mouse polyclonal antibodies against dog ZP3 fragment and mouse monoclonal antibodies against GnRH. Immunization of female FvB/J mice following two booster schedule with the above recombinant protein supplemented with alum led to high antibody titres against the immunogen as well as ZP3 and GnRH as determined by ELISA. The immune sera reacted with zona pellucida of mouse oocyte and also inhibited in-vitro fertilization. The qRT-PCR studies showed decrease in the ovarian GnRH receptor in mice immunized with the recombinant fusion protein. Mating studies revealed high contraceptive efficacy of the recombinant protein as in two independent experiments, 90% of the immunized female mice failed to conceive. Following one booster immunization schedule, 50% of the immunized female mice failed to conceive. However, in adjuvanted controls, all the female mice became pregnant. To conclude, the recombinant protein described herein has a good potential to be developed as candidate contraceptive vaccine.

Multi-channel programmable power supply with temperature compensation for silicon sensors

Silicon Photo-Multipliers (SiPMs) are increasingly becoming popular for discrete photon counting applications due to the wealth of advantages they offer over conventional photo-detectors such as photo-multiplier tubes and hybrid photo-diodes. SiPMs are used in variety of applications ranging from high energy physics and nuclear physics experiments to medical diagnostics. The gain of a SiPM is directly proportional to the difference between applied and breakdown voltage of the device. However, the breakdown voltage depends critically on the ambient temperature and has a large temperature co-efficient in the range of 40-60 mV/°C resulting in a typical gain variation of 3%-5%/°C [Dinu et al., in IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE, 2010), p. 215]. We plan to use the SiPM as a replacement for PMT in the cosmic ray experiment (GRAPES-3) at Ooty [Gupta et al., Nucl. Instrum. Methods Phys. Res., Sect. A 540, 311 (2005)]. There the SiPMs will be operated in an outdoor environment subjected to temperature variation of about 15 °C over a day. A gain variation of more than 50% was observed for such large variations in the temperature. To stabilize the gain of the SiPM under such operating conditions, a low-cost, multi-channel programmable power supply (0-90 V) was designed that simultaneously provides the bias voltage to 16 SiPMs. The programmable power supply (PPS) was designed to automatically adjust the operating voltage for each channel with a built-in closed loop temperature feedback mechanism. The PPS provides bias voltage with a precision of 6 mV and measures the load current with a precision of 1 nA. Using this PPS, a gain stability of 0.5% for SiPM (Hamamatsu, S10931-050P) has been demonstrated over a wide temperature range of 15 °C. The design methodology of the PPS system, its validation, and the results of the tests carried out on the SiPM is presented in this article. The proposed design also has the capability of gain stabilization of devices with non-linear thermal response.

Generation and Characterization of Monoclonal Antibodies Specific to Avian Influenza H5N1 Hemagglutinin Protein

Highly pathogenic avian influenza (HPAI) H5N1 virus has in the past breached the species barrier from infected domestic poultry to humans in close contact. Although human-to-human transmission has previously not been reported, HPAI H5N1 virus has pandemic potential owing to gain of function mutation(s) and/or genetic reassortment with human influenza A viruses. Monoclonal antibodies (MAbs) have been used for diagnosis as well as specific therapeutic candidates in several disease conditions including viral infections in humans. In this study, we describe the preliminary characterization of four murine MAbs developed against recombinant hemagglutinin (rHA) protein of avian H5N1 A/turkey/Turkey/1/2005 virus that are either highly specific or broadly reactive against HA from other H5N1 subtype viruses, such as A/Hong Kong/213/03, A/Common magpie/Hong Kong/2256/2006, and A/Barheaded goose/Quinghai/14/2008. The antibody binding is specific to H5N1 HAs, as none of the antibodies bound H1N1, H2N2, H3N2, or B/Brisbane/60/2008 HAs. Out of the four MAbs, one of them (MA-7) also reacted weakly with the rHA protein of H7N9 A/Anhui/1/2013. All four MAbs bound H5 HA (A/turkey/Turkey/1/2005) with high affinity with an equilibrium dissociation constant (KD) ranging between 0.05 and 10.30 nM. One of the MAbs (MA-1) also showed hemagglutination inhibition activity (HI titer; 31.25 μg/mL) against the homologous A/turkey/Turkey/1/2005 H5N1 virus. These antibodies may be useful in developing diagnostic tools for detection of influenza H5N1 virus infection.