Disposable paper electrodes for detection of changes in dopamine concentrations in rat brain homogenates

Dopamine, the main catecholamine neurotransmitter plays an important role in renal, cardiovascular, central nervous systems, and pathophysiological processes. The abnormal dopamine levels can result in neurological disorders such as Parkinson's, Alzheimer's, schizophrenia, acute anxiety, neuroblastoma and also contribute to cognitive dysfunctions. Given the widespread importance of dopamine concentration levels, it is imperative to develop sensors that are able to monitor dopamine. Herein, we have developed pre-anodized disposable paper electrode modified with 1-pyrenebutyric acid, for the selective and sensitive determination of dopamine. The sensor was characterized with Fourier transform infrared spectroscopy, Energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques for addressing the robust formation and electrochemical activity. The modified electrode exhibited excellent electrocatalytic activity towards dopamine without the common interference from ascorbic acid. The calibration plot for the dopamine sensor resulted linear range from 0.003 μM to 0.5 μM with a detection limit of 0.11 nM. The sensor's potential utility was tested by monitoring dopamine concentration changes in rat brain homogenates when subjected to neurotoxicity. The developed sensor was validated with gold-standard UV-Vis spectroscopy studies and computational studies were performed to understand the interaction between 1-pyrenebutyric acid and dopamine.

Combination of self-assembling system and N,O-carboxymethyl chitosan improves ocular residence of anti-glaucoma drug

Glaucoma is known to be one of the principal causes of vision loss due to elevated intraocular pressure. Currently, latanoprost eye drops is used as first-line treatment for glaucoma; however, it possesses low bioavailability due to rapid precorneal clearance. A novel delivery system with a mucoadhesive property could overcome this problem. Therefore, we attempt to develop a combination of self-assembling latanoprost nanomicelles (Latcel) and a mucoadhesive polymer (N,O-carboxymethyl chitosan: N,O-CMC) to improve the corneal residence time. Latcel was developed using Poloxamer-407 by thin film hydration method, followed by the addition of N,O-CMC using simple solvation to obtain Latcel-CMC and characterized using various physicochemical characterization techniques. The particle size of Latcel-CMC was 94.07 ± 2.48 nm and a zeta potential of -16.03 ± 0.66 mV, with a sustained release for 24h whereas marketed latanoprost drops released 90 % of the drug within 1h. In vitro cytotoxicity studies, HET-CAM, and in vivo Draize test showed the biocompatibility of Latcel-CMC. Cellular uptake studies performed using fluorescein isothiocyanate (FITC) loaded nanomicelles in human corneal epithelial cells indicates the increased cellular uptake as compare to plain FITC solution. In vivo ocular residence time was evaluated in Wistar rats using Indocyanine green (ICG) loaded nanomicelles by an in vivo imaging system (IVIS), indicating Latcel-CMC (8h) has better residence time than plain ICG solution (2h). The Latcel-CMC showed improved corneal residence time and sustained release of latanoprost due to increased mucoadhesion. Thus, the developed N,O-Carboxymethyl chitosan based nanomicelles eye drop could be a better strategy than conventional eye drops for topical delivery of latanoprost to treat glaucoma.

A promising 'single' and 'dual' drug-nanocomposite enriched contact lens for the management of glaucoma in response to the tear fluid enzyme

Glaucoma is a neurodegenerative condition that results in the damage of retinal ganglion cells due to elevated intraocular pressure (IOP). To curtail the limitations associated with conventional treatments such as eye drops and ocular suspensions, we have developed 'single' and 'dual' drug delivery contact lenses (CLs), that is, latanoprost (LP) and latanoprost-timolol (LP-TM) deliverable CLs, in response to lysozyme (Lyz), which is abundant in the lacrimal fluid. Since chitosan (CS) can entrap more of the drug and also undergo hydrolysis in the presence of Lyz, we have employed CS for the composite preparation. The CL fabrication was performed by free radical copolymerization of poly(2-hydroxyethyl methacrylate) (pHEMA) in the presence of the drug-loaded nanocomposite with UV-curing initiators using the pre-drug loading strategy. The surface morphological, optical and mechanical investigations confirmed the presence of the drugs, ≥80% transparency, the adequate flexibility and biocompatibility of both the CLs. The in vitro release experiments showed the release of 95.86% LP from LP-CL, and 83.87% LP and 86.70% TM from LP-TM-CL in the presence of 1.5 mg mL-1 of Lyz in 72 h. In vitro biocompatibility assay against human corneal epithelial (HCE) cells and ex vivo experiments on HET-CAM confirmed that the fabricated LP-CL and LP-TM-CL are well tolerated. Moreover, in vivo safety evaluations of CLs on New Zealand white rabbit eyes suggest no sign of irritation to the ocular tissues within 72 h of observation. Hence, the study suggests that the 'single' and 'dual' drug-loaded CLs could open a new avenue to manage glaucoma by maintaining mean diurnal IOP.

Development of mucoadhesive Timolol loaded chitosan-nanocomposite to treat glaucoma

Timolol Maleate is an aqueous soluble β-blocker antiglaucoma drug used to suppress intraocular pressure. Several commercially available ocular formulations are not effective in delivering to the target site due to their water-soluble property and low mucoadhesiveness. Hence, there is a requirement for a highly mucoadhesive drug-loaded nanocomposite to suppress intraocular pressure with enhanced bioavailability. Herein, we have prepared a mucoadhesive Timolol-loaded graphene quantum dot-chitosan-nanocomposite to treat glaucoma in response to lysozyme, secreted in the tear fluid. The as-prepared nanocomposite has been characterized through high resolution-transmission electron microscopic, X-ray photoelectron spectroscopic, X-ray diffraction, and Fourier transform infrared spectral studies. The nanocomposite showed 93.74 % encapsulation efficiency with a loading capacity of 7.73 %. Further, 89.26 %, 95.62 %, and 99.29 % of drug release were observed from the nanocomposite in the presence of 1, 1.5, and 2 mg/mL of lysozyme. The mucoadhesion property has been confirmed by the increment in the particle size, fluorescence spectral variations, and Fourier transform infrared spectroscopic studies in the presence of mucin nanoparticles of size 291 nm. Interestingly, mucoadhesion has been demonstrated by pointing to the quenching in the luminescence of mucin. Further, in vitro biocompatibility assay on human corneal epithelial cells showed ≥80 % cell viability. Hence, this study offers the utilization of naturally secreting enzymes for drug delivery applications instead of uncontrolled pH and temperature-triggered releases.

A clinical pilot study for the detection of sphingomyelinase in leptospirosis patient's urine at tertiary care hospital

Purpose

Leptospirosis is a perplexing mystification for many clinicians. Clinically often underdiagnosed due to lack of a rapid, sensitive, and specific diagnostic test. Currently available diagnostic tests have their own limitations; therefore, monitoring biomarkers that contribute an essential role in pathogenesis is crucial. Herein, a pilot study was conducted to detect the presence of sphingomyelinase in urine of leptospirosis patients.

Methods

Blood and urine samples were collected from 140 patients having febrile illness. Samples were analyzed through culturing, dark-field microscopy, detecting anti-leptospiral antibodies by MAT, IgM ELISA, Leptocheck-WB and screening for sphingomyelinase using a sphingomyelinase assay kit.

Results

Out of 140 febrile illness patients, 22.14 % were tested leptospirosis, 33.57 % were dengue, 25 % scrub typhus, 18.57 % malaria and 0.71 % co-infection (dengue-leptospirosis). MAT seropositivity of 19.28 % (27/140) was confirmed with the highest agglutinant determined against serovar Icterohaemorrhagiae RGA followed by Autumnalis, Australis, and Pyrogens. IgM ELISA and Leptocheck-WB positivity was 16.42 % and 13.57 % respectively. Whereas culture and dark-field microscopy showed a sensitivity of 4.28 % and 2.1 %, respectively. Out of 31 confirmed cases of leptospirosis, sphingomyelinase was detected in the urine of 25 (80.64 %) patients, MAT positivity was seen in 87.09 % and culture positivity was seen in 12.90 % of cases.

Conclusion

Detection of sphingomyelinase in the urine of a leptospirosis patient and its absence in other febrile illnesses like dengue, malaria and scrub typhus establish evidence of secretion of sphingomyelinase in urine during leptospiral infection. Hence, sphingomyelinase could be used as a potential diagnostic biomarker to detect leptospirosis in a non-invasive way.

Synthesis, properties and potential applications of photoluminescent carbon nanoparticles: A review

Photoluminescent-carbon nanoparticles (PL-CNPs) are a new class of materials that received immense interest among researchers due to their distinct characteristics, including photoluminescence, high surface-to-volume ratio, low cost, ease of synthesis, high quantum yield, and biocompatibility. By exploiting these outstanding properties, many studies have been reported on its utility as sensors, photocatalysts, probes for bio-imaging, and optoelectronics applications. From clinical applications to point-of-care test devices, drug loading to tracking of drug delivery, and other research innovations demonstrated PL-CNPs as an emerging material that could substitute conventional approaches. However, some of the PL-CNPs have poor PL properties and selectivity due to the presence of impurities (e.g., molecular fluorophores) and unfavourable surface charges by the passivation molecules, which impede their applications in many fields. To address these issues, many researchers have been paying great attention to developing new PL-CNPs with different composite combinations to achieve high PL properties and selectivity. Herein, we thoroughly discussed the recent development of various synthetic strategies employed to prepare PL-CNPs, doping effects, photostability, biocompatibility, and applications in sensing, bioimaging, and drug delivery fields. Moreover, the review discussed the limitations, future direction, and perspectives of PL-CNPs in possible potential applications.

Direct Electron Transfer of Glucose Oxidase on Pre-Anodized Paper/Carbon Electrodes Modified through Zero-Length Cross-Linkers for Glucose Biosensors

A disposable paper-based glucose biosensor with direct electron transfer (DET) of glucose oxidase (GOX) was developed through simple covalent immobilization of GOX on a carbon electrode surface using zero-length cross-linkers. This glucose biosensor exhibited a high electron transfer rate (ks, 3.363 s^-1) as well as good affinity (km, 0.03 mM) for GOX while keeping innate enzymatic activities. Furthermore, the DET-based glucose detection was accomplished by employing both square wave voltammetry and chronoamperometric techniques, and it achieved a glucose detection range from 5.4 mg/dL to 900 mg/dL, which is wider than most commercially available glucometers. This low-cost DET glucose biosensor showed remarkable selectivity, and the use of the negative operating potential avoided interference from other common electroactive compounds. It has great potential to monitor different stages of diabetes from hypoglycemic to hyperglycemic states, especially for self-monitoring of blood glucose.

Ni/Ni(OH)2-rGO nanocomposites sensor for the detection of long forgotten mycotoxin, xanthomegnin

Xanthomegnin, a known fungal toxin, secondary metabolite, and pigment diffuses from the dermatophytes has gained attention as local virulence factor because of the mutagenicity, toxicity, cytocidal, and immunosuppressive properties. Not only as a dermatophyte in skin related disorders, the production of xanthomegnin is implicated as a powerful diagnostic marker in patients suffering from ocular mycoses. Incidentally also attributed to death in livestock's majorly by exposing themselves to food-borne fungi like Aspergillus and Penicillium. The production of xanthomegnin in dermetophytic species Trichophyton rubrum, found commonly in infected skin and nails. In this study nickel/nickel hydroxide nanoparticles decorated reduced graphene oxide (Ni/Ni(OH)₂-rGO) modified glassy carbon electrode has been successfully used for non-enzymatic detection of xanthomegnin. The Ni/Ni(OH)₂-rGO composites were synthesized through a simple microwave assisted technique with less harmful reducing agent. The UV-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS), and electrochemical investigations demonstrated the robust formation of the sensor. The sensor exhibited improved electrochemical properties with enhanced electrochemical active area and excellent electrochemical behavior towards xanthomegnin detection with a limit of detection of 0.12 μM. The selectivity, stability, and analytical recovery studies proved the potential use of the sensor for the detection of xanthomegnin in real samples. Further, the sensor successfully detected xanthomegnin produced by the Trichophyton rubrum, the most common superficial fungus, accounting for at least 60% of all superficial fungal infections in humans. Validation studies showed satisfiable and quantifiable amount of xanthomegnin in comparison with common bench mark UV-Vis studies meant for fungal mycotoxin detection.

Leptospiral sphingomyelinase Sph2 as a potential biomarker for diagnosis of leptospirosis

Leptospirosis is an underestimated infectious tropical disease caused by the spirochetes belonging to the genus Leptospira. Leptospirosis is grossly underdiagnosed due to its myriad symptoms, varying from mild febrile illness to severe haemorrhage. Laboratory tests for leptospirosis is an extremely important and potent way for disease diagnosis, as the clinical manifestations are very similar to other febrile diseases. Currently available diagnostic techniques are time-consuming, require expertise and sophisticated instruments, and cannot identify the disease at an early phase of infection. Early diagnosis of leptospirosis is the need of the hour while considering the severe complications after the infection and the rate of mortality after misdiagnosis. Secretion of Leptospira-specific sphingomyelinases in leptospirosis patient's urine within a few days of the onset of infection is quite common and is a virulence factor present only in pathogenic Leptospira species. Herein, the structural and functional importance of leptospiral sphingomyelinase Sph2 in leptospirosis pathogenesis, as well as the potential of screening urinary Sph2 for diagnosis and the scope for developing a rapid and easily affordable point-of-care test for urinary leptospiral sphingomyelinase Sph2 as an alternative to current diagnostic methods are discussed.

Defatted silkworm pupae meal as an alternative protein source for cattle

Silkworm pupae meal (SWP) is a protein-rich by-product of the silk reeling industry, available in a significant quantity. However, there has been little and insignificant research into the use of SWP in ruminants to date. In this view, the present study was conducted in two phases to evaluate the effect of different inclusion levels of defatted silkworm pupae meal (DSWP) on rumen fermentation, microbial protein synthesis and nutrient utilisation in cattle fed on finger millet straw (FMS)-based diet. Four isonitrogenous concentrate mixtures (CM) were prepared with DSWP replacing soybean meal (SBM) protein at 0 (T0), 10 (T1), 20 (T2) and 30% (T3). In phase I, a rumen fermentation experiment was conducted in a 4 × 4 Latin square design using four crossbred steers to study the effect of different levels of DSWP on rumen fermentation. No significant difference (P > 0.05) was observed in rumen fermentation parameters such as pH, ammonia nitrogen (NH₃-N) and total volatile fatty acids (VFA) among the experimental groups. In phase II, the digestibility trial was conducted in 20 crossbred cattle (311.2 ± 4.81 kg), which were divided into four experimental groups of five animals each in a completely randomised design to study the effect of different rations (T0, T1, T2, T3) on microbial protein synthesis and nutrient utilisation. The intake and digestibility of nutrients, excretion of urinary purine derivatives and microbial protein synthesis were not significantly different among the experimental groups. In addition, feeding DSWP revealed no significant (P > 0.05) change in the blood biochemical parameters of animals. Furthermore, at the same price as SBM, DSWP provides two units more crude protein. Therefore, the results of the present study indicated that DSWP can be incorporated into the ration of cattle up to 30% by replacing SBM without affecting rumen fermentation pattern and nutrient utilisation.

Towards CRISPR powered electrochemical sensing for smart diagnostics

Even though global health has been steadily improved, the global disease burden associated with communicable and non-communicable diseases extensively increased healthcare expenditure. The present COVID-19 pandemic scenario has again ascertained the importance of clinical diagnostics as a basis to make life-saving decisions. In this context, there is a need for developing next-generation integrated smart real-time responsive biosensors with high selectivity and sensitivity. The emergence of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas biosensing systems has shown remarkable potential for developing next-generation biosensors. CRISPR/Cas integrated electrochemical biosensors (E-CRISPR) stands out with excellent properties. In this opinionated review, we illustrate the rapidly evolving applications for E-CRISPR-integrated detection systems towards biosensing and the future scope associated with E-CRISPR based diagnostics.

Paper-based field-effect transistor sensors

The present scenario in the world largely demands affordable, fast, recyclable, and flexible electronic devices for bio sensing. Varieties of paper-based devices such as microfluidics paper electrodes, paper diodes, and paper-based transistors etc. have been developed and validated. Most of the fabrication techniques published so far have focused on economic, environment-friendly straightforward methods to develop paper-based field-effect transistors (PFET) sensors, additionally, explored their applications. The synthetic-free, mechanically flexible, biocompatible, and signal amplification capability render PFET based sensors for wearable device makers. Modified organic/inorganic PFETs identify target analytes based on the electrical signal and endow them as perfect transducers. In the field of PFET bio sensing technology, numerous challenges are needed to be discussed to proceed forward in biomedical and other analytical applications. Realizing biologically or chemically modified PFET having an exceptional signal to noise ratio, specificity, with rapid detection ability is challenging. This review recapitulates the fabrication techniques, performances of various PFET sensors, and summarizes the report by concluding remarks including the limitations of the existing PFET based sensors and the future holds in regards to the sustainable nature of PFET.

Why chitosan could be apt candidate for glaucoma drug delivery - An overview

Most of the people in the world are affected by glaucoma, which leads to irreversible blindness. Several patient friendly treatments are available, nevertheless medications lack an easy and efficient way of sustained delivery. To make the delivery with enhanced bioavailability, biodegradable and non-biodegradable polymers-based drug carriers are explored. However, ocular drug delivery issues have not been resolved yet due to less adhesiveness, poor penetration ability, pH, and temperature dependent burst releases. Chitosan is found to be effective for ocular drug delivery due to excellent physio-chemical properties in terms of overcoming the existing issues. In this review, we aim to highlight why it has been chosen and the holy grail for ocular drug delivery. Besides, we have comprehensively reviewed recent patents on chitosan as a platform for ocular drug delivery and future perspectives on factors, lacunae and challenges that need to be addressed for better ocular delivery methods for glaucoma management.

A new method to amplify colorimetric signals of paper-based nanobiosensors for simple and sensitive pancreatic cancer biomarker detection

A low-cost, sensitive, and disposable paper-based immunosensor for instrument-free colorimetric detection of pancreatic cancer biomarker PEAK1 was reported for the first time by capitalizing the catalytic properties of gold nanoparticles in colour dye degradation. This simple signal amplification method enhances the detection sensitivity by about 10 fold.

A Low-Cost Nanomaterial-based Electrochemical Immunosensor on Paper for High-Sensitivity Early Detection of Pancreatic Cancer

Due to the lack of specific early detection methods for pancreatic cancer, it usually goes undetected until it is advanced. By employing paper-based electrodes (PPE), herein we for the first time developed a disposable low-cost paper-based immunosensor for rapid early quantitative detection of pancreatic cancer with a new biomarker, pseudopodium-enriched atypical kinase one, SGK269 (PEAK1). The immunosensor was constructed by fabricating PPEs immobilized with the versatile nanomaterial graphene oxide for the incorporation of antibodies to form an immunosensing platform, without the need of complicated surface modification. After it was confirmed that the PPEs exhibited excellent electrochemical properties, a sandwich-type electrochemical immunosensor was subsequently constructed by employing graphene oxide layers immobilized with anti-PEAK1, and the antibody conjugated with gold nanoparticles (AuNPs-tagged-Anti PEAK1). Further, spectral and surface characteristic studies confirmed the formation of the immunosensing platform. The immunosensor for PEAK1 exhibited a wide linear range between 10 pg mL^-1 and 10⁶ pg mL^-1 with a low limit of detection (LOD) of 10 pg mL^-1. The obtained results point towards rapid, sensitive, and specific early diagnosis of pancreatic cancer at the point of care and other low-resource settings.

Enhanced electroactivity and substrate affinity of microperoxidase-11 attached to pyrene-linkers π–π stacked on carbon nanostructure electrodes

An exceptionally large electroactively connected microperoxidase-11 (MP-11) with strong affinity for organic peroxide and offering a high electrocatalytic reduction current density of 7.5 mA cm⁻² is achieved for the first time.

Synthesis, characterization, and electrochemical applications of carbon nanoparticles derived from castor oil soot

A simple procedure for the modification of carbon nanoparticles (CNPs) from castor oil soot using acid treatment was described herein. Characterization studies revealed the presence of edge plane sites and surface carbon-oxygen functionalities at the surface of the CNP material. Voltammetric studies revealed the increased electrochemical activity of the CNP-modified electrode toward various biologically important molecules, including dopamine, uric acid, dihydronicotinamide adenine dinucleotide, tyrosine, and serotonin, relative to those obtained using the unmodified electrode. The improved electro-oxidation potentials for these compounds-and, thereby, the enhanced sensitivity of related sensors-was due directly to the presence of surface C(δ+)O(δ-) functional groups and the greater number of edge plane sites developed after acid treatment of the soot sample.

Integrin tyrosine phosphorylation in platelet signaling

The beta 3 integrin cytoplasmic tyrosine (ICY) motif of alpha IIb beta 3 becomes tyrosine phosphorylated during platelet aggregation, causing Shc and myosin to interact with the beta-integrin cytoplasmic domain. Platelets from mice lacking beta 3 ICY motif tyrosines formed defective aggregates and poorly retracted clots, establishing integrin tyrosine phosphorylation as a key mediator of beta 3-integrin signals.

Beta3 tyrosine phosphorylation in alphaIIbbeta3 (platelet membrane GP IIb-IIIa) outside-in integrin signaling

The platelet integrin alphaIIbbeta3 not only binds fibrinogen and von Willebrand factor to mediate platelet aggregation and adhesion, it also serves as a signaling receptor. Platelet agonists such as ADP, thrombin and collagen induce "inside-out" signaling which activates the receptor function of alphaIIbbeta3 for soluble fibrinogen. Subsequent platelet aggregation leads to "outside-in" signaling, inducing platelet aggregate stabilization and triggering a variety of functions important to platelet physiology. This review focuses on the role of beta3 tyrosine phosphorylation in alphaIIbbeta3 outside-in signaling. Tyrosine phosphorylation of beta3 in platelets is a dynamic process which is initiated upon platelet aggregation and also by adhesion of platelets to immobilized fibrinogen. Tyrosine phosphorylation occurs on the beta3 integrin cytoplasmic tyrosine (ICY) domain, a conserved motif found in the beta subunits of several integrins. Beta3 ICY domain tyrosine phosphorylation induces the recruitment of two proteins to the cytoplasmic domains of alphaIIbbeta3: the cytoskeletal protein myosin, important to clot retraction; and the signaling adapter protein Shc, important to platelet stimulation, The critical role of beta3 tyrosine phosphorylation to platelet function was established by the diYF mouse, a novel strain which expresses an alphaIIbbeta3 in which the two beta3 ICY domain tyrosines have been mutated to phenylalanine. These mice are selectively impaired in outside-in alphaIIbbeta3 signaling, with defective aggregation and clot-retraction responses in vitro, and an in vivo bleeding defect which is characterized by a pronounced tendency to rebleed. Taken together, the data suggest that the beta3 tyrosine phosphorylation signaling mechanism is important to alphaIIbbeta3 function and might be applicable to a wide variety of integrin-mediated events.

Cardiovascular overexpression of transforming growth factor-beta(1) causes abnormal yolk sac vasculogenesis and early embryonic death

Transforming growth factor-beta(1) (TGF-beta(1)) is expressed in the adult and embryonic vasculature; however, the biological consequences of increased vascular TGF-beta(1) expression remain controversial. To establish an experimental setting for investigating the role of increased TGF-beta(1) in vascular development and disease, we generated transgenic mice in which a cDNA encoding a constitutively active form of TGF-beta(1) is expressed from the SM22alpha promoter. This promoter fragment directs transgene expression to smooth muscle cells of large arteries in late-term embryos and postnatal mice. We confirmed the anticipated pattern of SM22alpha-directed transgene expression (heart, somites, and vasculature of the embryo and yolk sac) in embryos carrying an SM22alpha-beta-galactosidase transgene. SM22alpha- beta-galactosidase transgenic mice were born at the expected frequency (13%); however, nearly all SM22alpha-TGF-beta(1) transgenic mice died before E11.5. SM22alpha-TGF-beta(1) transgenic embryos identified at E8.5 to E10.5 had growth retardation and both gross and microscopic abnormalities of the yolk sac vasculature. Overexpression of TGF-beta(1) from the SM22alpha promoter is lethal at E8.5 to E10.5, most likely because of yolk sac insufficiency. Investigation of the consequences of increased vascular TGF-beta(1) expression in adults may require a conditional transgenic approach. Moreover, because the SM22alpha promoter drives transgene expression in the yolk sac vasculature at a time when embryonic survival is dependent on yolk sac function, use of the SM22alpha promoter to drive expression of "vasculoactive" transgenes may be particularly likely to cause embryonic death.

Mitogen-activated protein kinase mediates erythropoietin-induced phosphorylation of the TAL1/SCL transcription factor in murine proerythroblasts

Ectopic expression of the basic helix-loop-helix transcription factor TAL1 (or SCL) is the most frequent gain-of-function mutation in T-cell acute lymphoblastic leukaemia. Gene-knockout studies in mice have demonstrated that TAL1 is required for embryonic and adult haematopoiesis, and considerable evidence suggests it also has important functions in terminal erythroid differentiation. We reported previously that TAL1 phosphorylation is stimulated by erythropoietin in splenic proerythroblasts isolated from mice infected with the anaemia-inducing strain of Friend virus and show here the signalling pathway responsible. Erythropoietin was found to stimulate nuclear mitogen-activated protein kinase activity in addition to TAL1 protein phosphorylation, both of which were quantitatively inhibited by the mitogen-activated protein kinase kinase inhibitor PD 098059 and the phosphatidylinositol 3-kinase inhibitor wortmannin. Tryptic phosphopeptide analysis of radiolabelled TAL1 immunoprecipitated from nuclear extracts of Friend virus-induced proerythroblasts revealed that phosphorylation of Ser(122), shown previously to be a substrate for the mitogen-activated protein kinase ERK1 (extracellular signal-regulated protein kinase) in vitro, was specifically, although not exclusively, increased by erythropoietin and inhibited by wortmannin and PD 098059. These results are consistent with an erythropoietin-stimulated signalling pathway in which there is direct activation of a mitogen-activated protein kinase kinase by phosphatidylinositol 3-kinase and identify TAL1 as one of its nuclear targets. These data suggest, in addition, a specific mechanism by which the principal regulator of erythroid differentiation could enhance TAL1 function, in addition to increasing its expression.

Evaluation of a new recombinant DNA hepatitis B vaccine (Shanvac-B)

We assessed the efficacy and safety of Shanvac-B, a new recombinant hepatitis B vaccine developed in India. Eighty-one healthy volunteers (75 women, 6 men; aged 18-40 yr), negative for markers for hepatitis B and HIV, received 20 microg of the vaccine intramuscularly at 0, 1 and 2 months. Forty-three (53%) seroconverted at one month after dose 1; of these, 26% were seroprotected (anti-HBs> 10 mIU/mL). Seroprotection at one month after doses 2 and 3 was 99% and 100%, respectively. Geometric mean titres of anti-HBs in subjects who seroconverted were 11 (range 2-366), 266 (8-7469) and 2246 (102-23680) mIU/mL, respectively. One subject developed urticarial rash after the second dose; there was no other adverse event. We conclude that this vaccine is safe and efficacious, providing significant protection even after two doses.

Intracranial fungal granuloma

BACKGROUND

Intracranial fungal granulomas are uncommon and their pathogenesis, clinical picture, and effectiveness of therapy remains unclear.

METHODS

Thirty-two cases were studied retrospectively in two groups: (1) Rhinocerebral group (22 cases) had a chronic paranasal sinus (PNS) disease with secondary involvement of skull base, cranial nerves, and/or brain. The granulomas were adherent to dura, firm, avascular, and tough, requiring a knife to cut. (2) Primary intracranial group (10 cases) had no detectable PNS lesion at initial presentation. The granulomas were soft, suckable, and contained pus or necrotic material.

RESULTS

Postoperative and overall mortality were 37.5% and 50%, respectively. Meningoencephalitis was the most common cause of death. Altered sensorium, pus in the granuloma, and/or severe brain edema were poor prognostic factors. All survivors except four have symptomatic residual or recurrent lesions.

CONCLUSION

Early diagnosis with MRI or stereotactic biopsy, radical surgery, and high dose and chronic suppressive chemotherapy may improve overall results in these cases.

Target-dependent effect of phosphorylation on the DNA binding activity of the TAL1/SCL oncoprotein

Activation of the TAL1 (or SCL) gene, initially identified through its involvement by a recurrent chromosomal translocation, is the most frequent gain-of-function mutation recognized in T-cell acute lymphoblastic leukemia. The translational products of this gene contain the basic domain helix-loop-helix motif characteristic of a family of transcription factors that bind to a consensus nucleotide sequence termed the E-box. Previous work established that the TAL1 proteins are phosphorylated exclusively on serine and identified Ser122 as a substrate for the mitogen-activated protein kinase ERK-1. We provide evidence that an additional serine residue, Ser172, located in a conserved region proximal to the DNA binding domain and sharing homology with a similarly positioned sequence in the HLH oncoprotein LYL1, can be phosphorylated in vitro and in vivo by the catalytic subunit of cAMP-dependent protein kinase. Phosphorylation was found to alter TAL1 DNA binding activity in a target-dependent manner that was influenced by both the specific CANNTG E-box core motif and its flanking sequences. In contrast, the ability of TAL1 to interact with the E2A gene product E12 and its subcellular localization in transfected COS cells were unaffected by Ser172 phosphorylation. These results suggest this serine residue has a regulatory function and indicate a mechanism by which phosphorylation could affect DNA binding site discrimination.

Role of 17 beta-estradiol and progesterone in the regulation of synthesis and secretion of chorionic gonadotropin by the first trimester human placenta

The role of 17 beta-estradiol and progesterone in the regulation of synthesis of chorionic gonadotropin (CG) by first trimester human placenta has been studied using 1,4,6 androstatriene 3-17-dione to block the synthesis of 17 beta-estradiol or tamoxifen to block its action at receptor level and RU486 to block the action of progesterone at the receptor level. Results indicate that the synthesis of CG is negatively modulated by 17 beta-estradiol and positively modulated by progesterone as judged by the change in the levels of immunoreactive CG, alpha- and beta-CG mRNA and in vitro translation, as well as biosynthesis of alpha- and beta-CG and, finally, nuclear run off transcription.

Erythropoietin stimulates transcription of the TAL1/SCL gene and phosphorylation of its protein products

Activation of the TAL1 (or SCL) gene, originally identified through its involvement by a recurrent chromosomal translocation, is the most frequent molecular lesion recognized in T-cell acute lymphoblastic leukemia. The protein products of this gene contain the basic-helix-loop-helix motif characteristic of a large family of transcription factors that bind to the canonical DNA sequence CANNTG as protein heterodimers. TAL1 expression by erythroid cells in vivo and in chemical-induced erythroleukemia cell lines in vivo suggested the gene might regulate aspects of erythroid differentiation. Since the terminal events of erythropoiesis are controlled by the glycoprotein hormone erythropoietin (Epo), we investigated whether the expression or activity of the TAL1 gene and its protein products were affected by Epo in splenic erythroblasts from mice infected with an anemia-inducing strain of Friend virus (FVA cells). Epo elicited a rapid, dose-related increase in TAL1 mRNA by increasing transcription of the gene and stabilizing one of its mRNAs. An Epo-inducible TAL1 DNA binding activity was identified in FVA cell nuclear extracts that subsequently decayed despite accumulating mRNA and protein. Induction of DNA binding activity was associated temporally with Epo-induced phosphorylation of nuclear TAL1 protein. These results indicate that Epo acts at both transcriptional and posttranscriptional levels on the TAL1 locus in Friend virus-induced erythroblasts and establish a link between Epo signaling mechanisms and a member of a family of transcription factors involved in the differentiation of diverse cell lineages.

Growing fracture of the skull: report of an unusual case

The authors report a case of a growing fracture of the skull in an elderly woman who remained asymptomatic for over 6 decades and presented at the age of 62 years with symptoms akin to the syndrome of the trephined. Successful duraplasty and cranioplasty were done with disappearance of all symptoms. A brief review of the relevant literature is also presented.

A simple and efficient method for the purification of seminal plasmin, an antimicrobial protein from bovine seminal plasma

A method involving direct affinity chromatography of undialysed bovine seminal plasma on a calmodulin-agarose column was developed for the purification of seminalplasmin. Seminalplasmin thus obtained was further purified from any contaminants left by ion-exchange chromatography on a short CM-Sepharose column. The method gave an excellent yield of seminalplasmin (0.7 mg per ml seminal plasma) that showed 100% inhibition of bacterial growth at a concentration of 10 micrograms/ml. The purified seminalplasmin was found to be homogeneous as tested by HPLC on a reverse-phase column and SDS-PAGE.

Haemostatic derangement in patients with intracranial tumours

Forty-five patients with brain tumours were studied for evidence of any haemostatic abnormalities in the preoperative and intraoperative period. An abnormality was found in 44 of the patients in the preoperative period and in all the patients during the operation. One patient developed acute disseminated intravascular coagulation. A change in the haemostatic abnormality from the preoperative to the intraoperative period was demonstrated in 9 of the patients. The histological nature of the tumour did not influence the haemostatic derangement. A shortened euglobulin lysis time, prolonged thrombin time, increased fibrin degradation products and abnormal fibrinogen levels were the common isolated abnormalities. When considered together, chronic disseminated intravascular coagulation (DIC) with or without fibrinolysis and fibrinolysis with or without DIC were the commonest abnormalities. Although some degree of haemostatic derangement is found in a high proportion of patients with brain tumours, clinically relevant abnormalities are rare.

Induction of autolysis in starved Escherichia coli cells by seminalplasmin, an antimicrobial protein from bovine seminal plasma

A pair of relA+ and relA E. coli strains, otherwise isogenic, were studied with regard to the susceptibility of starved cells to lysis induced by the natural peptide seminalplasmin. Starved relA cells were more sensitive to seminalplasmin-induced lysis when compared to starved relA+ cells. Nevertheless, pronounced lysis of starved relA+ cells was observed with increase in the concentration of seminalplasmin. In contrast, ampicillin could not lyse starved relA+ cells even at very high concentrations. Further, seminalplasmin could cause loss of viability and degradation of peptidoglycan in starved relA+ cells. These observations suggest that, unlike many other antibiotics, seminalplasmin can induce autolysis under the conditions of a stringent response.

Precipitation of DNA by polyethylene glycol and ethanol

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Seminalplasmin, an antimicrobial protein from bovine seminal plasma, inhibits peptidoglycan synthesis in Escherichia coli

Seminalplasmin, an antimicrobial protein from bovine seminal plasma, inhibited peptidoglycan synthesis in Escherichia coli in a concentration-dependent manner. The inhibition of peptidoglycan synthesis appears to be a cause rather than a consequence of growth inhibition as it was observed soon after the addition of the antibiotic even in E. coli cells whose growth was totally inhibited by chloramphenicol.

Isolation and characterization of autolysis-defective mutants of Escherichia coli that are resistant to the lytic activity of seminalplasmin

Two temperature-sensitive autolysis-defective mutants of Escherichia coli were isolated and shown to be resistant to lysis induced by seminalplasmin, an antimicrobial protein from bovine seminal plasma, as well as to lysis induced by ampicillin, D-cycloserine and nocardicin, at 37 or 42 degrees C but not at 30 degrees C. The mutants were, however, sensitive to inhibition of RNA synthesis by seminalplasmin even at the nonpermissive temperature. Temperature-resistant revertants of the mutants were sensitive to lysis induced by the various antibiotics at 37 or 42 degrees C. The mutations in both strains were mapped at 58 min on the E. coli linkage map. The lysis resistance of the mutants was phenotypically suppressed by the addition of NaCl. Partial suppression of the lysis-resistant phenotype was also observed in a relA genetic background.

Bacteriolytic activity of seminalplasmin

Seminalplasmin, an antimicrobial protein from bovine seminal plasma, lysed both Gram-positive and Gram-negative bacteria but not Candida albicans. The lytic activity was not lysozyme-like and was not affected by inhibitors of RNA or protein synthesis or by azide; it was strongly inhibited by divalent cations like Ca2+, Mn2+ and Mg2+ at millimolar concentrations. Maximum lysis of Escherichia coli was obtained at 37 degrees C; heat treatment of E. coli drastically reduced its susceptibility to lysis by seminalplasmin. E. coli cells in the stationary phase of growth were lysed much less than those in the exponential phase, and those grown in an enriched medium were lysed much more than those grown in a minimal medium. It appears that the lytic activity of seminalplasmin is due to the activation of an autolysin.

Transcription but not translation is required for EDTA-induced autolysis in Escherichia coli

Rifampicin, but not chloramphenicol or other inhibitors of translation, inhibited EDTA-induced autolysis in Escherichia coli. Inhibition of EDTA-induced autolysis in E. coli was also observed with nalidixic acid and novobiocin, inhibitors of topoisomerase II. Rifampicin or nalidixic acid-resistant mutants of E. coli were resistant to the inhibitory effect of the respective antibiotic on EDTA-induced autolysis. The implications of these studies in regard to our understanding of the regulation of autolysis in E. coli are discussed.

Cardiac depression on syringing the ear. A case report

While syringing of the ear was being done to clean the ear canal, the heart stopped beating suddenly. This was presumed to be due to stimulation of the vagus nerve, which supplies both the external auditory meatus plus the tympanic membrane and the cardiac muscle. There were also other signs of cholingergic nerve stimulation. The patient recovered in less than a minute, after external cardiac massage.

Expression of a chemically synthesized human alpha 1 interferon gene

Cells of Escherichia coli containing a chemically synthesized human alpha 1 interferon (IFN-alpha 1) gene, under control of the lac promoter, make a product with biological properties indistinguishable from those of the natural IFN-alpha 1 [antiviral activity, acid stability, species crossreactivity, inactivation by antisera directed against leukocyte or Namalwa cell interferon, and stimulation of (2'-5')oligoadenylate synthetase activity]. Similar levels of IFN synthesis were obtained when the expression unit (lac promoter plus synthetic IFN-alpha 1 gene) was transplanted into the obligate methylotroph Methylophilus methylotrophus.

Effect of the antitumor antibiotic chromomycin A3 on the humoral immune response in rats

Chromomycin A3 (250 mug/kg) suppressed the humoral immune response in rats against sheep erythrocytes when administered 48 h or later after antigenic stimulus. The antibiotic at this dose enhanced immunity when given along with or before antigen administration. The natural heterohemagglutinin levels in rabbits and guinea pigs were not affected by the antibiotic (10 mug/kg per day x 7).

Effect of cell concentration on the uptake of amino acids by rat liver parenchymal cells in suspension

The accumulation of several amino acids in the acid-soluble fraction and their incorporation into protein in rat liver parenchymal cell suspensions, has been shown to depend on the concentration of cells in the incubation medium; the uptake, both in the acid-soluble and the acid-insoluble fractions, decreased as the cell concentration increased from 0.03 X 10(6) cells/ml upwards, reaching a plateau at high cell concentrations (3-5 X 10(6) cells/ml). The uptake values at high cell concentrations were the same as those obtained in liver slices in which a similar effect was not observed. Evidence is presented which suggests that this phenomenon is mediated by a material released from the cells in suspension, which is inhibitory to enhancement of the uptake of amino acids by these cells over and above the value obtained in normal, adult liver slices.