DTI correlates of cognition in conventional MRI of normal-appearing brain in patients with clinical features of subacute combined degeneration and biochemically proven vitamin B(12) deficiency

BACKGROUND AND PURPOSE

Vitamin B12 deficiency may cause neural injury that results in cognitive deficits. The main purpose of our study was to evaluate morphometric and microstructural changes in the brain and relate them to cognition in subacute combined degeneration of the spinal cord and patients with biochemically deficient vitamin B12.

MATERIALS AND METHODS

Fifty-one patients were recruited and underwent nerve-conduction velocity tests and routine hematologic examinations. Serum vitamin B12 and homocystine levels were also measured. All patients and 46 age- and sex-matched controls underwent cervical spine and brain MR imaging along with cognition tests. MR imaging included conventional scans and DTI. Voxel-based morphometry was performed for determining the WM and GM volumes, based on T1-weighted images. DTI measures that included fractional anisotropy, ADC, radial diffusivity, and axial diffusivity were determined by using tract-based statistics.

RESULTS

None of the patients showed any abnormality on conventional MR imaging. No significant changes in GM and WM volumes were observed in patients compared with controls. Significant reductions in the fractional anisotropy and an increase in ADC and radial diffusivity values were observed in multiple brain regions in patients compared with controls. These changes were confirmed on the region-of-interest analysis. Neuropsychological scores were significantly different in patients compared with controls and showed significant correlation with fractional anisotropy and radial diffusivity in a few brain regions.

CONCLUSIONS

Microstructural changes are seen in WM regions on DTI in patients with vitamin B12 deficiency and correlate with cognition scores. DTI can be used for objective assessment of microstructural changes in the brain in vitamin B12 deficiency.

Dental pulp stem cells immobilized in alginate microspheres for applications in bone tissue engineering

AIM

To immobilize dental pulp stem cells (DPSC) in alginate microspheres and to determine cell viability, proliferation, stem cell characteristics and osteogenic potential of the immobilized DPSCs.

METHODOLOGY

Human DPSCs isolated from the dental pulp were immobilized in 1% w/v alginate microspheres. Viability and proliferation of immobilized DPSCs were determined by trypan blue and MTT assay, respectively. Stem cell characteristics of DPSCs post immobilization were verified by labelling the cells with CD73 and CD90. Osteogenic potential of immobilized DPSCs was assessed by the presence of osteocalcin. Alizarin red staining and O-cresolphthalein complexone method confirmed and quantified calcium deposition. A final reverse transcriptase PCR evaluated the expression of osteogenic markers - ALP, Runx-2 and OCN.

RESULTS

More than 80% of immobilized DPSCs were viable throughout the 3-week study. Proliferation appeared controlled and consistent unlike DPSCs in the control group. Presence of CD73 and CD90 markers confirmed the stem cell nature of immobilized DPSCs. The presence of osteocalcin, an osteoblastic marker, was confirmed in the microspheres on day 21. Mineralization assays showed high calcium deposition indicating elevated osteogenic potential of immobilized DPSCs. Osteogenic genes- ALP, Runx-2 and OCN were also upregulated in immobilized DPSCs. Surprisingly, immobilized DPSCs in the control group cultured in conventional stem cell media showed upregulation of osteogenic genes and expressed osteocalcin.

CONCLUSION

Dental pulp stem cells immobilized in alginate hydrogels exhibit enhanced osteogenic potential while maintaining high cell viability both of which are fundamental for bone tissue regeneration.

Polymeric colloidal particulate systems: intelligent tools for intracellular targeting of antileishmanial cargos

INTRODUCTION

Targeted cargo delivery systems can overcome drawbacks associated with antileishmanials delivery, by defeating challenges of physiological barriers. Various colloidal particulate systems have been developed in the past; few of them even achieved success in the market, but still are limited in some ways.

AREAS COVERED

This review is focused on the pathobiology of leishmaniasis, interactions of particulate systems with biological environment, targeting strategies along with current conventional and vaccine therapies with special emphasis on polymeric nanotechnology for effective antileishmanial cargo delivery.

EXPERT OPINION

The problems concerned with limited accessibility of chemotherapeutic cargos in conventional modes to Leishmania-harboring macrophages, their toxicity, and resistant parasitic strain development can be sorted out through target-specific delivery of cargos. Vaccination is another therapeutic approach employing antigen alone or adjuvant combinations delivered by means of a carrier, and can provide preventive measures against human leishmaniasis (HL). Therefore, there is an urgent need of designing site-specific antileishmanial cargo carriers for safe and effective management of HL. Among various colloidal carriers, polymeric particulate systems hold tremendous potential as an effective delivery tool by providing control over spatial and temporal distribution of cargos after systemic or localized administration along with enhancing their stability profile at a comparatively cost-effective price leading to improved chances of commercial applicability.

Effect of gold nanoparticles on depolarization characteristics of Intralipid tissue phantom

We report results of studies on the effect of different shapes and sizes of gold nanoparticles (GNPs) on the depolarization characteristics of Intralipid tissue phantoms. For a given extinction coefficient, the absorption characteristics of the GNPs contributed more to the depolarization of the turbid medium, and the contribution of scattering was significant only for the larger-sized particles. For rod-shaped GNPs, their depolarization plays an important role in the low scattering regime in which the depolarization properties of the nanoparticles (NPs) dominate in the turbid medium even if the contribution of the scattering from the NPs is about an order of magnitude less. For highly scattering samples, GNP absorption significantly modulates the depolarization spectra of the turbid medium.

A complete genetic linkage map and QTL analyses for bast fibre quality traits, yield and yield components in jute (Corchorus olitorius L.)

We report the first complete microsatellite genetic map of jute (Corchorus olitorius L.; 2n = 2x = 14) using an F6 recombinant inbred population. Of the 403 microsatellite markers screened, 82 were mapped on the seven linkage groups (LGs) that covered a total genetic distance of 799.9 cM, with an average marker interval of 10.7 cM. LG5 had the longest and LG7 the shortest genetic lengths, whereas LG1 had the maximum and LG7 the minimum number of markers. Segregation distortion of microsatellite loci was high (61%), with the majority of them (76%) skewed towards the female parent. Genomewide non-parametric single-marker analysis in combination with multiple quantitative trait loci (QTL)-models (MQM) mapping detected 26 definitive QTLs for bast fibre quality, yield and yield-related traits. These were unevenly distributed on six LGs, as colocalized clusters, at genomic sectors marked by 15 microsatellite loci. LG1 was the QTL-richest map sector, with the densest colocalized clusters of QTLs governing fibre yield, yield-related traits and tensile strength. Expectedly, favorable QTLs were derived from the desirable parents, except for nearly all of those of fibre fineness, which might be due to the creation of new gene combinations. Our results will be a good starting point for further genome analyses in jute.

T1-weighted dynamic contrast-enhanced MR evaluation of different stages of neurocysticercosis and its relationship with serum MMP-9 expression

BACKGROUND AND PURPOSE

Epileptogenesis in NCC is associated with perilesional inflammation and disruption in BBB. We quantified BBB in different stages of NCC by using DCE-MR imaging to look for the differences in perfusion indices and to correlate these indices with serum MMP-9 expression.

MATERIALS AND METHODS

DCE-MR imaging along with conventional MR imaging was performed in 57 single cysticercous brain lesions to quantify the kep, K(trans), and ve around the lesions, which were in different stages of evolution. There were 6 lesions in the vesicular stage and 17 lesions each in the colloidal, granular-nodular, and calcified stages. Serum MMP-9 was quantified from all patients, whereas perfusion indices were quantified from all stages except for the vesicular stage.

RESULTS

We observed significant differences among the 3 stages of NCC in serum MMP-9 expression as well as DCE-derived kep values. In addition, kep showed a strongly significant positive correlation with MMP-9 expression when modeled with the individual stage of the disease as well as with all stages when pooled together. Other DCE-derived hemodynamic and pharmacokinetic parameters showed inconsistent differences with each stage of the disease. The correlation of DCE-derived parameters with serum MMP-9 expression and edema volume also showed inconsistency with the stage of the disease.

CONCLUSIONS

We conclude that kep correlates best with serum MMP-9 expression among the pharmacokinetic indices and most closely represents the degree of BBB breakdown, which is highest in the colloidal stage and lowest in the calcified stage. kep may be used as a noninvasive image biomarker of BBB breakdown in different stages of NCC.

Effect of curcumin on the diffusion kinetics of a hemicyanine dye, LDS-698, across a lipid bilayer probed by second harmonic spectroscopy

The diffusion kinetics of a hemicyanine dye, LDS-698, across model membrane bilayers was studied in real time by the surface specific second harmonic technique. Using liposomes made from different headgroups, it has been established that the diffusion is initiated by electrostatic adsorption of the positively charged dye to the outer surface of negatively charged liposomes and its time constant is affected by the rigidity of the bilayer. In the presence of the liphophilic drug curcumin (curcumin/lipid mole ratio ~ 0.2), the diffusion of LDS-698 was observed to be faster by ~56 times (from 780 to 14 s) at 25 °C. Under similar curcumin concentration, when cholesterol containing liposomes are used at 2 °C, the observed diffusion time constant increases from 14 to 65 s, showing that the effect of curcumin is superior to the effect of increasing bilayer rigidity on the diffusion process. Control experiments with other lipophilic molecules such as DPH and Nile Red showed that the effect of liposomal curcumin is superior. Consistent with previous reports of curcumin affecting the bilayer organization, this study additionally demonstrates increased permeability of liposomal curcumin, in particular against organic cations. It is speculated that origin of this enhanced membrane permeability by lipophilic molecules may depend upon the interaction of the molecule with the polar headgroup region of the lipid which, in turn, is expected to depend on the chemical structure of the molecule.

Comparative efficacy evaluation of disinfectants routinely used in hospital practice: India

AIM

The aim of this study was to evaluate and compare practically achieved disinfection efficacy of some locally available disinfectants on surfaces and infectious microbiological hospital waste.

MATERIALS AND METHODS

Seven disinfectants were tested at concentrations recommended by manufacturers on rough and smooth surfaces that were contaminated experimentally by locally circulating isolates of methicillin-resistant Staphylococcus aureus, multidrug-resistant Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter aerogenes, Pseudomonas aeruginosa strains, standard isolate of Salmonella typhi and Candida albicans. Reduction in microbial counts before and after surface disinfection was expressed as log reduction. A very heavy microbial waste load was simulated by immersing culture plates with heavy microbial growth in disinfectants. Daily, a sample of disinfectant was taken and subjected to in-use test.

RESULTS

The highest average log reduction of test microbes on the rough surface was given by DesNet (5.05) and Bacillocid special (5.02). A comparable average log reduction of test microbes on a smooth steel surface was noted (5.68, 5.67, 5.50) for Lysol, Bacillocid sp. and DesNet, respectively. In the discard jars, Bacillocid special worked satisfactorily for 4 days, DesNet for 3 days and Hi-giene Germitol for 1 day. The remainder of the disinfectants failed in the in-use test on Day 1. Phenolics, although widely used in our settings, may not be as good surface disinfectants as newer formulations like DesNet and Bacillocid special.

CONCLUSIONS

Newer quaternary ammonium compounds and aldehyde formulations were found to be the best disinfectants for disinfection of heavy contamination.

Microfluidic sorting with blinking optical traps

It is shown that by appropriately choosing the periodicity of a blinking optical trap only larger sized colloidal spheres can be selectively trapped out of a mixed population. This happens because smaller sized, more agile, spheres escape out of the trap volume during the off period of the trap beam. Therefore, by scanning an array of blinking traps over a mixed sample, bigger spheres can be forced to move with the traps and eventually could be taken to the output side. Experimental demonstration of sorting between 1 µm and 2 µm diameter silica spheres is presented.

Diffusion of chlorin-p6 across phosphatidyl choline liposome bilayer probed by second harmonic generation

We have investigated the diffusion of the photosensitizer Chlorin-p(6) (Cp(6)) across a egg lecithin lipid bilayer at different pH by the Second Harmonic Generation (SHG) method. Cp(6) has three ionizable carboxylic acid groups, and consequently, neutral and several ionic forms of Cp(6) are expected to be present in the pH range 3-8. The absorption spectra of Cp(6) get considerably modified in the presence of liposomes as the pH is decreased indicating that the drug liposome binding is pH dependent. The first pK(a) of interconversion (D-C) has been identified at pH ~7.0 by fluorescence measurement in an earlier work. In this work, the second pK(a) of interconversion (C-B) has been identified at pH ~4.8 by the hyper-Rayleigh scattering method. At acidic pH (3, 4, and 5), where species A, B, and C are dominant, the addition of liposomes to a Cp(6) solution generates an instantaneous rise (less than 1 s) in the second harmonic (SH) signal followed by decays whose time constants ranged from ten to hundreds of seconds. The instantaneous rise is attributed to the adsorption of Cp(6) to the outer lipid bilayer, and the decay is attributed to the diffusion of the neutral and charged (A and B) species of the drug. The observed fast and slow time constants for diffusion in the pH range 3-5 are attributed to the neutral (A) and ionic form (B) of Cp(6), respectively. At pH 6, the intensity of the generated SH signals on the addition of liposome reduced, and at physiological pH, it was too weak to be detected. These results are consistent with previous studies that show that the interaction between Cp(6) and egg-PC liposomes is pH dependent. At lower pH due to the presence of the hydrophobic species (A and B) of Cp(6), its interaction with liposomes is strong, and at higher pH, the abundance of the negatively charged hydrophilic species (C and D) decreases the interaction with the like charged liposomes. We have also studied the effect of increasing the bilayer rigidity by decreasing the temperature of the medium or by incorporating 50 mol % cholesterol in the lipid bilayer and observed that lowering of temperature has more profound effect on the diffusion rates. The characteristics of the SH signal changed significantly when liposomes incorporating 50 mol % cholesterol were used at a low (3 °C) temperature. Under these conditions, the SH signal consisted of an instantaneous (<1s) followed by a slower rise (10-90s), and then, it decayed on a much longer time scale. This slow rise of the SH signal at pH 3 and 4 may be attributed to the temperature dependent adsorption of the anionic species (B) of Cp(6) with the liposomes. Further investigations are required in order to understand clearly the pH dependent diffusion of this drug across lipid bilayers.

Effect of crystallization heat treatment on the microstructure of niobium-doped fluorapatite glass-ceramics

Our goal was to study the effect of heat treatment temperature and heating rate on the microstructure and crystalline phases and assess the domain of existence of submicrometer fluorapatite crystals in niobium-doped fluorapatite glass-ceramics for biomedical applications. Glass-ceramic specimens were prepared by casting and heat treatment between 700 and 1200°C using a fast or a slow heating rate. The microstructure was characterized by atomic force microscopy and scanning electron microscopy. Crystalline phases were analyzed by x-ray diffraction. AFM of the as-cast glass revealed that amorphous phase separation occurred in this system. XRD confirmed the presence of fluorapatite in all specimens, together with forsterite and enstatite at higher temperatures. Both heating rate and heat treatment temperature strongly influenced microstructure and crystallinity. A dual microstructure with submicrometer fluorapatite crystals and polygonal forsterite crystals was obtained when slow heating rates and crystallization temperatures between 950 and 1100°C were used. Needle-shaped fluorapatite crystals appeared after heat treatment above 1100°C. Fast heating rates led to an increase in crystal size. Heat treatment temperatures should remain below 1100°C, together with slow heating rates, to prevent crystal dissolution, and preserve a dual microstructure of finely dispersed submicrometer crystals without growth of needle-shaped crystals.

Endovascular repair of abdominal aortic aneurysm does not improve early survival versus open repair in patients younger than 60 years

OBJECTIVES

Multiple randomised trials have demonstrated lower perioperative mortality after endovascular aneurysm repair (EVAR) compared to open surgical repair for infrarenal abdominal aortic aneurysms (AAAs). However, in these trials the mortality advantage for EVAR is being lost within 2 years of repair and the patients evaluated are relatively older with no study specifically comparing EVAR and open repair for patients younger than 60 years of age.

DESIGN

A retrospective analysis of prospectively collected data.

MATERIALS AND METHODS

Patients younger than 60 years of age who underwent EVAR and open surgical repair for elective infrarenal AAA were identified from the 2007-09 National Surgical Quality Improvement Program (NSQIP) - a prospective database maintained at 237 centres across the United States. Univariate and multivariate analyses were performed.

RESULTS

Of the 651 patients, 369 (56.7%) underwent EVAR and 282 (43.3%) underwent open repair. Thirty-day mortality for EVAR and open repair were 1.1% and 0.4%, respectively. This was not significantly different on univariate (P = 0.22) as well as multivariate (P = 0.69) analysis after controlling for other co-morbidities. On multivariate analysis, body mass index, history of stroke and bleeding disorder prior to surgery were associated with a higher 30-day mortality after AAA repair (combined open and EVAR).

CONCLUSIONS

These contemporary results demonstrate that the 30-day mortality rate after open repair is similar to that after EVAR in patients younger than 60 years with infrarenal AAA.

Midodrine in patients with cirrhosis and refractory or recurrent ascites: a randomized pilot study

BACKGROUND & AIMS

Splanchnic arterial vasodilatation plays an important role in cirrhotic ascites. The aim of this study was to evaluate the effects of long term administration of midodrine on systemic hemodynamics, renal function, and control of ascites in patients with cirrhosis and refractory or recurrent ascites.

METHODS

Forty cirrhotic patients with refractory or recurrent ascites were prospectively studied after long term administration of midodrine plus standard medical therapy (n=20) or standard medical therapy alone (n=20) in a randomized controlled trial at a tertiary centre.

RESULTS

A significant increase in urinary volume, urinary sodium excretion, mean arterial pressure, and decrease in plasma renin activity (p<0.05) was noted after 1 month of midodrine administration. There was also a significant decrease in cardiac output and an increase in systemic vascular resistance after midodrine therapy at 3 months (p<0.05). There was no change in glomerular filtration rate and model for end-stage liver disease (MELD) score. Midodrine plus standard medical therapy was significantly superior to standard medical therapy alone in the control of ascites (p=0.013) at 3 months. The mortality rate in the standard medical therapy group was significantly higher than the midodrine group (p<0.046). There was no significant difference in the frequency of various complications at the end of follow-up.

CONCLUSIONS

The results of this randomized pilot study suggest that midodrine plus standard medical therapy improves the systemic hemodynamics without any renal or hepatic dysfunction in these patients and is superior to standard medical therapy alone for the control of ascites.

Temperature-dependent index of refraction of monoclinic Ga2O3 single crystal

We present temperature-dependent refractive index along crystallographic b[010] and a direction perpendicular to (100)-plane for monoclinic phase (β) Ga(2)O(3) single crystal grown by the optical floating zone technique. The experimental results are consistent with the theoretical result of Litimein et al.1. Also, the Sellmeier equation for wavelengths in the range of 0.4-1.55 μm is formulated at different temperatures in the range of 30-175 °C. The thermal coefficient of refractive index in the above specified range is ~10(-5)/°C.

Chitosan enhances mineralization during osteoblast differentiation of human bone marrow-derived mesenchymal stem cells, by upregulating the associated genes

OBJECTIVES

  Chitosan is widely used as a scaffold for bone tissue engineering. However, up-to-date, no previous detailed study has been conducted to elucidate any mechanism of osteogenesis by chitosan itself. Here, we have evaluated effects of chitosan-coated tissue culture plates on adhesion and osteoblast differentiation processes of human mesenchymal stem cells (hMSCs), isolated from adult bone marrow.

MATERIALS AND METHODS

  Tissue culture plates coated with chitosan at different coating densities were used to evaluate the effects on hMSC adhesion and osteoblast differentiation. hMSCs were induced to differentiate into osteoblasts on the chitosan-coated plates and were evaluated using established techniques: alkaline phosphatase assay, demonstration of presence of calcium and real time PCR.

RESULTS

  The cells adhered to plates of lower coating density of chitosan, but formed viable cell aggregates at higher coating density (100 μg/sq.cm). Coating density of 25 μg/sq.cm, supporting cell adhesion was chosen for osteoblast differentiation experiments. Differentiating hMSCs showed higher mineral deposition and calcium content on chitosan-coated plates. Chitosan upregulated genes associated with calcium binding and mineralization such as collagen type 1 alpha 1, integrin-binding sialoprotein, osteopontin, osteonectin and osteocalcin, significantly.

CONCLUSIONS

  We demonstrate for the first time that chitosan enhanced mineralization by upregulating the associated genes. Thus, the study may help clinical situations promoting use of chitosan in bone mineralization, necessary for healing non-union fractures and more.

Soluble VEGFR1 (sVEGFR1) as a novel marker of amyotrophic lateral sclerosis (ALS) in the North Indian ALS patients

BACKGROUND AND PURPOSE

  North Indian patients with amyotrophic lateral sclerosis (ALS) exhibit substantially extended survival time after onset of the disease as compared to their Western counterparts. Earlier, we found that vascular endothelial growth factor-A (VEGF-A) may be associated with increased survival of these patients. We now measured soluble vascular endothelial growth factor receptor-1 (sVEGFR1), an inhibitor receptor for VEGF-A, in these patients with ALS.

METHODS

Patients with sporadic ALS (n = 36) attending the Neurology Outpatient at Post Graduate Institute of Medical Education and Research (PGIMER) at Chandigarh were included on the basis of El Escorial criteria. The sVEGFR1 levels were analyzed in serum of these patients using enzyme-linked immunosorbent assay (ELISA) and compared with normal controls (n = 36).

RESULTS

  Soluble vascular endothelial growth factor receptor-1 was found to be decreased significantly in serum of patients with ALS. Serum obtained from definite ALS revealed significantly lower sVEGFR1 as compared to probable ALS. However, there was no difference in serum sVEGFR1 levels between male and female patients with ALS.

CONCLUSIONS

Soluble vascular endothelial growth factor receptor-1 downregulation may result in increased serum VEGF-A reported previously in our patients with ALS and may indicate the activation of compensatory mechanism in response to neurodegeneration. The lower serum sVEGFR1 levels may have a possible clinicopathological association, if not causal, to the extended survival of North Indian patients with ALS; however, the result needs further investigations particularly in comparable Caucasian ALS population.

Noninvasive imaging of ethanol-induced developmental defects in zebrafish embryos using optical coherence tomography

In this article, we report the use of optical coherence tomography for noninvasive cross-sectional real-time imaging of ethanol-induced developmental defects in zebrafish embryos larvae. For ethanol concentration of over 300 mM, developmental defects of eye (shrinkage and retinal abnormalities), malformation of the notochord and ataxia arising due to the toxic effects of ethanol were observed in OCT images from 3 days post fertilization onwards. The results suggest that OCT could be a valuable tool for noninvasive assessment of birth defects in small animal systems.

Antineoplastic potential of medicinal plants

Cancer is one of the most dreaded diseases worldwide and the incidence is on the rise in both developing and developed countries. It is treated by chemotherapy, radiotherapy and surgery. In spite of advances in treatment strategies, cancer still remains a major cause of death. Research is on for development of better drugs which are more effective and simultaneously cause fewer side effects. Plants have been used for the treatment of various ailments of man and animals since ages. They are being screened extensively to explore the possibility of development of economically viable anticancer drugs. Natural products of plant origin currently constitute a considerable proportion of commercially available antineoplastic drugs. This review gives an insight into commercially available anticancer drugs of plant origin and also patents granted to plant derived components, extracts and polyherbal formulations possessing anticancer activity. The exhaustive work reviewed here on antineoplastic activity of various plants both in vitro and experimental models throughout the world will help design further research in this field.

The Role of anti-HBc IgM in Screening of Blood Donors

BACKGROUND

Transfusion transmitted hepatitis B has always been a dreaded disease, with incidence of increased transmission through donated blood. The screening test for hepatitis B infection is detection of HBsAg that does not rule out the risk of transmission of hepatitis B as the donor may be in the 'window period'. During this period, detection of the antibody to the hepatitis B core antigen (anti-HBc) IgM type serves as a useful serological marker. The aim of this study was to screen blood donors for anti-HBc type IgM and anti - HBc Ag total for detection and to find their incidence amongst blood donors.

METHODS

2552 voluntary blood donors were screened by the ELISA method for HBsAg and anti - HBc IgM and other mandatory screening markers. 704 of the test blood samples were also screened for anti-HBc total.

RESULT

Of the 2552 donor, 47 (1.84 %) cases were HBsAg positive. A total of 11 (0.43 %) blood units were reactive for HBcAg IgM and of these, 10 (0.39 %) were HBsAg negative and reactive for anti-HBcAg IgM. Of the 704 samples tested for anti - HBcAg total, 112 (15.9%) samples were reactive.

CONCLUSION

Screening of blood for anti-HBc total is practical in the western world as the incidence of HBsAg and anti-HBc is low in these countries and these positive blood units for anti - HBcAg total can be discarded. This may not be practical in India as the incidence of anti- HBcAg total is high in our population. It is recommended that all blood units should be tested for anti - HBc IgM for infectivity status of the blood donors in the window period and to discard blood if positive.