Hippocampal Avoidance Whole BRAIN Radiotherapy (HA-WBRT) with Simultaneous Integrated BOOST (SIB) vs. HA-WBRT in Multiple Brain Metastases: A Dosimetric Comparison

PURPOSE/OBJECTIVE(S)

There has been a paradigm shift in managing multiple brain metastases. Various options include SRS, WBRT, and WBRT with Hippocampal avoidance (HA-WBRT). There is no consensus for the treatment of multiple brain metastases (>3 brain metastases). A new technique that has proven feasible is dose escalation in the form of simultaneous integrated boost. The aim of this study was to compare the dosimetry parameters of HA-WBRT plus simultaneous integrated boost versus HA-WBRT alone in multiple brain metastases.

MATERIALS/METHODS

In a prospective trial,16 patients with multiple brain metastasis (≥ 3) from various primaries with good performance scores (ECOG PS ≤ 2) are recruited. All patients underwent CT simulation (1.5 mm slice thickness) and RT plans for HA-WBRT with (SIB) and HA-WBRT alone were made. A 5 mm margin was given to the bilateral hippocampus for Hippocampal Avoidance. In the HA-WBRT plan for the PTV i.e., whole brain plus 3 mm margin minus hippocampal avoidance region (H.A.), a dose of 30 Gy in 10 fractions is prescribed over two weeks. In HA-WBRT with SIB, a dose of 30 Gy in 10 fractions over two weeks is prescribed for the PTV, which is the clinical target volume, minus the hippocampal avoidance region (H.A.) minus the PTV Mets (1 mm margin to the GTV). A simultaneous Integrated Boost of 42.5 Gy in 10 # over two weeks is prescribed for PTVmets. Planning was done using a VMAT technique with 6MV F.F.F. beam energy in a treatment planning software.

RESULTS

The mean B/L hippocampus volume is 3.47 cc. The mean dose of PTV D98% in HA-WBRT plans is 27.45 Gy, whereas in HA-WBRT with S.I.B. is 27.36 Gy (p = 0.90). V30 mean dose in HA-WBRT plans is 93.35%, and the mean dose in HA-WBRT SIB is 91.87% (p = 0.12). PTV D2% mean dose in HA-WBRT Is 36.06 Gy, and in HA-WBRT -S.I.B., it is 40.58 (p< 0.001). The mean bilateral hippocampus Dmax in HA-WBRT is 14.85 Gy, and in HA-WBRT-SIB is 14.25 Gy (p = 0.35). The mean Bilateral hippocampus D100% is 9.14 Gy in HA-WBRT and 9.01 Gy in HA-WBRT-SIB (p = 0.54). The mean brainstem Dmax in HA-WBRT is 36.82 Gy compared to 38.55 Gy in HA-WBRT-SIB (p = 0.02).

CONCLUSION

In patients planned for a simultaneous boost along with hippocampal sparing whole brain radiotherapy, the mean dose to the hippocampal region did not increase. The Dmax of Brainstem, optic chiasma is significantly higher in HA-WBRT-). Our study, the mean dose to PTVmets is more than 45 Gy and more than 50 Gy to GTV with a BED of more than 65 Gy (α/ß = 10) to the metastases, which is equivalent to some ablative dose regimens. Simultaneous integrated boost along with hippocampal sparing radiotherapy thus helps in sparing the hippocampus and delivering higher doses to the metastases and intermediate doses to the rest of the brain, addressing the microscopic disease.

Formulation and Development of Hyaluronic Acid based gel with Ketoconazole -Loaded Nanostructured Lipid Carriers in Fungal Infection

BACKGROUND

Ketoconazole is an imidazole ring containing antifungal agent used in the treatment of systemic fungal infections. It acts by blocking the synthesis of ergosterol, an essential component of the fungal cell membrane.

OBJECTIVE

The purpose of this work is to construct skin targeting ketoconazole nanostructured lipid carriers (NLCs) loaded hyaluronic acid (HA) modified gel to minimize side effects and provide a controlled release.

METHODS

The NLCs were prepared using emulsion sonication method and their optimized batches were characterized for X-ray diffraction, scanning electron microscopy and fourier transform infrared spectroscopy study. These batches were then incorporated into HA containing gel for convenient application. The final formulation was compared with the marketed formulation for studying its antifungal activity and drug diffusion.

RESULTS

Ketoconazole NLCs loaded hyaluronic acid formulation was successfully developed with desirable formulation parameters by using 23 Factorial design. In-vitro release study of developed formulation showed prolonged drug release (up to 5 hrs) while ex-vivo drug diffusion study on human cadaver skin showed better drug diffusion as compared with marketed formulation. Moreover, the release study and diffusion study results reflected the improvement of antifungal activity of the developed formulation against Candida albicans.

CONCLUSION

The work suggests that ketoconazole NLCs loaded HA modified gel provides prolonged release. The formulation also has good drug diffusion and antifungal activity and thus can act as a promising carrier for topical delivery of ketoconazole.

Assay discrepancies using human coagulation factor VIII chromogenic kits: Results from a plasma-derived factor VIII collaborative study (BSP112)

Chromogenic assay discrepancies were reported at General European Official Medicines Control Laboratories Network (GEON) meetings by laboratories testing FVIII-products. The objectives of the present investigation were to carry out a controlled collaborative study to examine these reports and to delineate the reasons for these discrepancies by assessing affected and unaffected FVIII products. The laboratories followed a strict study protocol, which included assessing their own individual observed factor X (FX) activation times, i.e. the time to reach 50% of maximal FX activation (T_1/2), for each chromogenic kit. This measurement was used, in parallel with the kit manufacturers' prescribed FX activation times, to assess the performance of the chromogenic potency assays on FVIII test products. This study confirmed a significant discrepancy between Coatest® and Coamatic® kits and between Siemens and Coamatic® kits when the kit manufacturers' prescribed T_1/2 incubation times were followed. Coamatic® kits tended to produce higher potencies than the Coatest® or Siemens kits. Furthermore, FX activation assays revealed marked differences between individual laboratories for all three chromogenic kits in the observed T_1/2 incubation times, which also did not correspond to the prescribed T_1/2 incubation times. The resulting differences in potency between kits, in some cases, were significantly reduced when using the actual observed T_1/2 incubation times instead of the prescribed T_1/2 incubation times. The study showed that FVIII potency discrepancies can occur between chromogenic kits. To compensate for this, laboratories should ideally perform FX activation curves for each new chromogenic kit in order to determine the correct observed T_1/2 incubation times, which can then be used to determine FVIII potencies in therapeutic concentrates.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  ×  6  ×  6 m 3 liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.

111 The Systemic Effects of Intra-Articular Steroid Injections- Should COVID-19 Change Our Practice?

Aim

The COVID-19 pandemic prompted us to review and often suspend services, while patients continue to suffer with painful musculoskeletal conditions. The diagnostic and therapeutic value of intra-articular corticosteroid injections (IACSI) cannot be denied. Current BOA guidelines advise giving the lowest effective dose for inflammatory arthritis and limit use in osteoarthritis to patients with high levels of pain and disability. We aimed to evaluate the literature pertaining to the use of IACSI and the potential systemic immunosuppressive effects.

Method

We searched Medline, using the terms “systemic effects of intra-articular steroid” and “clinical course of Coronavirus infection in patients with steroid use”, between 1997 and 2020.

Results

No studies specifically looked at the systemic effects of intra-articular steroids in the presence of COVID-19 infection; however, four studies were identified which concluded that intra-articular steroid injections resulted in sufficient systemic absorption to cause suppression of the hypothalamic-pituitary-adrenal axis and endogenous cortisol production. These effects are dose dependent and are more common in patients with inflammatory joint diseases. A further four RCT’s, including one systematic review, showed that suppressed cortisol concentration was associated with a significant increase in mortality.

Conclusions

There is a lack of evidence in relation to the use of intra-articular steroids in COVID-19. However, evidence suggests that intra-articular steroids can result in systemic absorption and suppression of endogenous cortisol production thus increasing the potential risk of complications of COVID-19. We therefore support cautious use of low dose steroid injections in patients with inflammatory arthritis, where no alternative treatment is available.

Calibration of the Ph. Eur. human coagulation Factor VIII Concentrate BRP batch 6

The European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for human coagulation Factor VIII (FVIII) Concentrate is used as working standard for potency determination of human coagulation FVIII preparations by chromogenic assay. BRP batch 5 was established in 2015 and its stocks were running low. Therefore, the European Directorate for the Quality of Medicines & HealthCare (EDQM) initiated a project (BSP156) for the calibration of a replacement batch. The potency of BRP batch 6 was assigned during an international collaborative study involving 16 laboratories worldwide, with reference to the WHO 8th International Standard (IS) and BRP batch 5. Participants were instructed to perform 3 independent FVIII potency assays following their own routine validated methods for the chromogenic assay, which is the assay prescribed by the Ph. Eur. As an outcome of the study, Ph. Eur. human coagulation FVIII Concentrate BRP batch 6 was assigned a consensus potency of 9.9 IU/ampoule for the chromogenic assay. The Ph. Eur. BRP batch 6 is a freeze-dried, plasma-derived concentrate. Based on accelerated degradation studies, the stability of the material is suitable for a reference preparation. The Ph. Eur. BRP batch 6 was adopted at the 167th session of the Ph. Eur. Commission in June 2020 and is available from the EDQM under product code H0920000.

De-colourization of textile effluent using immobilized Geotrichum candidum: an insight into mycoremediation

Textile effluent is generally complicated to manage because of its extremely noxious and recalcitrant coloured compositions. Mycoremediation is an extensively used strategy for the competent degradation of hazardous pollutants present in textile effluent. Fungus could be immobilized in synthetic or natural matrices. The current study shows the decolourization of the textile effluent by 85·5 and 98·5% within 6 h using suspended and immobilized fungus, Geotrichum candidum with optimized parameters like inoculum size (5%), pH (4·5), and temperature (30°C). To maintain a high biomass of fungal population and enhance the retention of fungal strain in the contaminated sites, the fungi need to be immobilized. Hence, the fungus was immobilized naturally onto the selected inert support that is, coconut fibres by the means of adsorption, where they grew as active films on the fibres after being grown in the culture broth. The optimized process parameters of inoculum size, fibre quantity and agitation speed for immobilized G. candidum were 5%, 2·2 g l^-1 of effluent and 100 rev min^-1 respectively. High level of laccase (22 and 25 U l^-1 in suspended and immobilized fungal cells treatment respectively) was observed during the process of decolourization and it was found that decolourization was directly proportional to the laccase activity. The UV-vis, FTIR, ¹ H NMR and GC-MS analyses of treated textile industrial wastewater revealed the degradation of toxic pollutants in the textile effluent and formation of lower molecular weight intermediates. The study revealed a higher efficacy of immobilized G. candidum in comparison to suspended fungal culture, employing ligninolytic enzyme laccase, which catalyzes the degradation/transformation of aromatic dyes in the textile effluent thus decolourizing it.

Elucidation of fungal dye-decolourizing peroxidase (DyP) and ligninolytic enzyme activities in decolourization and mineralization of azo dyes

AIM

The aim of the study is to investigate the efficiency of Geotrichum candidum in the decolourization and mineralization of synthetic azo dyes.

METHODS AND RESULTS

It includes screening of enzymes from G. candidum and its optimization, followed by decolourization and mineralization studies. Decolourization was observed to be maximum in methyl orange (94·6%) followed by Congo red (85%), trypan blue (70·4%) and Eriochrome Black T (55·6%) in 48 h, suggesting the plausible degradation of the azo dyes by G. candidum. The enzyme activity study showed that DyP-type peroxidase has highest activity of 900 mU ml^-1 compared to that of laccase (405 mU ml^-1 ) and lignin peroxidase (LiP) (324 mU ml^-1 ) at optimized pH (6) and temperature (35°C). Moreover, the rate of decolourization was found to be directly proportional to the production of laccase and LiP, unlike DyP-type peroxidase. Furthermore, mineralization study demonstrated reduction in aromatic amines, showing 20% mineralization of methyl orange.

CONCLUSION

Geotrichum candidum with its enzyme system is able to efficiently decolourize and mineralize the experimental azo dyes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The efficient decolourization and mineralization of azo dyes makes G. candidum a promising alternative in the treatment of textile effluent contaminated with azo dyes.

Evaluation of the Fibrin Binding Profile of two Anti-fibrin Monoclonal Antibodies

Two anti-fibrin monoclonal antibodies, MAbs 1H10 and 5F3, raised to human freeze-fractured fibrin and thrombin-treated N-terminal disulphide knot (T-NDSK), respectively, were compared for epitope binding to various domains of the fibrinogen/fibrin moiety. Using plasmin-mediated fibrinogen digests, immunoblots showed that both MAbs crossreacted strongly with fragments X and Y, weakly with fragment-E and not at all with fragment D. Purified fragments D and E used in an ELISA confirmed that MAbs 1H10 and 5F3 cross-reacted in a dose-response fashion with the isolated fragment-E, while there was no reaction with fragment-D. The two MAbs were similarly shown to react with fibrin-derived fragment-E. Surface Plasmon Resonance (SPR) technology, employed to further evaluate the epitopes in fibrin, showed that MAb 1 HI0 had a higher affinity for fragment-E (KD = 8.04 × 10-9 M) than MAb 5F3 (KD = 1.13 × 10-8 M). Individual association and dissociation rate constants of 7.97 × 105 M-1S-1 and 3.97 × 10-3S-1, respectively, for MAb 1H10, and 5.16 × 105 M-1s-1 and 3.62 × 10-3s-1, respectively, for MAb 5F3 were also obtained. A SPR inhibition assay confirmed that MAb 1H10 had a greater affinity for fragment-E than MAb 5F3. However individual isolated polypeptide chains of fibrinogen fragment E (E-Aα, E-Bβ, E-γ) showed no reaction with the two antibodies in ELISA, immunoblot or SPR analysis procedures. Furthermore, SPR pair-wise epitope mapping analysis revealed that MAbs 1H10 and 5F3 have in fact distinct epitopes on fragment-E. These distinct epitopes appeared to be a conformational amalgam of linear sequences in two or three of the polypeptide chains of fragment-E, or distinct conformational epitopes on one of the three subunit chains alone.

Endocrine regulation of sperm release

Spermiation (sperm release) is the culmination of a spermatid’s journey in the seminiferous epithelium. After a long association with the Sertoli cell, spermatids have to finally ‘let go’ of the support from Sertoli cells in order to be transported to the epididymis. Spermiation is a multistep process characterised by removal of excess spermatid cytoplasm, recycling of junctional adhesion molecules by endocytosis, extensive cytoskeletal remodelling and final spermatid disengagement. Successful execution of all these events requires coordinated regulation by endocrine and paracrine factors. This review focuses on the endocrine regulation of spermiation. With the aim of delineating how hormones control the various aspects of spermiation, this review provides an analysis of recent advances in research on the hormonal control of molecules associated with the spermiation machinery. Because spermiation is one of the most sensitive phases of spermatogenesis to variations in hormone levels, understanding their molecular control is imperative to advance our knowledge of the nuances of spermatogenesis and male fertility.

A Collaborative Study to Establish the 6th International Standard for Factor VIII Concentrate

A study was carried out to replace the 5th WHO International Standard (IS) for factor VIII concentrate, because of depletion of stocks. Two candidate concentrates (X and Y) were assayed as potential replacements against the 5th IS for FVIII concentrate, in a collaborative study involving 33 laboratories. Collaborators were asked to use the ISTH/SSC recommendations, including pre-dilution of concentrates in FVIII deficient plasma in their assays. Several laboratories performed more than one assay method and altogether there were 21 sets of assays with the one-stage method, 6 with the two-stage method and 26 with the chromogenic method. There was good agreement between laboratories using each method for the comparison of concentrates X and Y against the 5th IS, but the overall potencies by one-stage and chromogenic methods each differed by approximately 5% from the overall mean, with the chromogenic potency approximately 10% higher than the one-stage. Inter-laboratory agreement was slightly better for concentrate Y than X, and stability studies indicated that Y was more stable than X. After considering all the information, together with comments from participants and from the FVIII/FIX Subcommittee of the ISTH/SSC, candidate Y (NIBSC code [97/616]), was proposed and accepted in October, 1998, by the Expert Committee on Biological Standardisation of the World Health Organisation to be the 6th International Standard for Factor VIII Concentrate with an assigned potency of 8.5 IU/ampoule.

An in vitro experiment to simulate how easy tablets are to swallow

The compliance of patients to solid oral dosage forms is strongly conditioned by the perceived ease of swallowing, especially in geriatric and pediatric populations. This study proposes a method, based on an in vitro model of the human oropharyngeal cavity, to study quantitatively the oral phase of human swallowing in presence of single or multiple tablets. The dynamics of swallowing was investigated varying the size and shape of model tablets and adjusting the force applied to the mechanical setup to simulate tongue pressure variations among individuals. The evolution of the velocity of the bolus, the oral transit time, and the relative position of the solid oral dosage form within the liquid bolus were measured quantitatively from high speed camera recordings. Whenever the solid dosage forms were big enough to interact with the walls of the in vitro oral cavity, a strong effect of the volume of the medication in respect of its swallowing velocity was observed, with elongated tablets flowing faster than spherical tablets. Conversely, the geometrical properties of the solid oral dosage forms did not significantly affect the bolus dynamics when the cross section of the tablet was lower than 40% of that of the bolus. The oral phase of swallowing multiple tablets was also considered in the study by comparing different sizes while maintaining a constant total mass. The predictive power of different theories was also evaluated against the experimental results, providing a mechanistic interpretation of the dynamics of the in vitro oral phase of swallowing. These findings and this approach could pave the way for a better design of solid oral medications to address the special needs of children or patients with swallowing disorders and could help designing more successful sensory evaluations and clinical studies.

Calibration of the Ph. Eur. human coagulation Factor VIII concentrate BRP batch 5

The European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP) for Factor VIII Concentrate batch 5 was established through a collaborative study involving 14 laboratories organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) to be used as working standard for potency determination of human coagulation Factor VIII (FVIII) preparations. The potency of the BRP batch 5 was assigned with reference to the WHO 8^th International Standard (IS) for FVIII Concentrate and the BRP batch 4. Participants were instructed to perform 3 independent Factor VIII potency assays following their own routine validated methods by the chromogenic assay as it is the assay prescribed by the European Pharmacopoeia. This publication reports the results obtained during the study. The consensus potency, 9.9 IU/ampoule (n = 14) when assessed against both standards, with inter-laboratory geometric coefficients of variation (GCV) of 3.2 % and 1.9 % against the WHO 8^th IS and the BRP batch 4 respectively, was consistent with the expected value. The Ph. Eur. BRP batch 5 is a freeze-dried, plasma-derived concentrate. Based on accelerated degradation studies, the stability of the material is suitable as a reference preparation. The Ph. Eur. BRP batch 5 was adopted at the 151^st session of the European Pharmacopoeia Commission in March 2015 and is available from the EDQM.

International Nosocomial Infection Control Consortium report, data summary of 50 countries for 2010-2015: Device-associated module

BACKGROUND

We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2010-December 2015 in 703 intensive care units (ICUs) in Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific.

METHODS

During the 6-year study period, using Centers for Disease Control and Prevention National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI), we collected prospective data from 861,284 patients hospitalized in INICC hospital ICUs for an aggregate of 3,506,562 days.

RESULTS

Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the INICC medical-surgical ICUs, the pooled rate of central line-associated bloodstream infection, 4.1 per 1,000 central line-days, was nearly 5-fold higher than the 0.8 per 1,000 central line-days reported from comparable US ICUs, the overall rate of ventilator-associated pneumonia was also higher, 13.1 versus 0.9 per 1,000 ventilator-days, as was the rate of catheter-associated urinary tract infection, 5.07 versus 1.7 per 1,000 catheter-days. From blood cultures samples, frequencies of resistance of Pseudomonas isolates to amikacin (29.87% vs 10%) and to imipenem (44.3% vs 26.1%), and of Klebsiella pneumoniae isolates to ceftazidime (73.2% vs 28.8%) and to imipenem (43.27% vs 12.8%) were also higher in the INICC ICUs compared with CDC-NHSN ICUs.

CONCLUSIONS

Although DA-HAIs in INICC ICU patients continue to be higher than the rates reported in CDC-NSHN ICUs representing the developed world, we have observed a significant trend toward the reduction of DA-HAI rates in INICC ICUs as shown in each international report. It is INICC's main goal to continue facilitating education, training, and basic and cost-effective tools and resources, such as standardized forms and an online platform, to tackle this problem effectively and systematically.

Linear dichroism and optical anisotropy of silver nanoprisms in polymer films

We present optical studies of two different size distributions of silver triangular nanoprisms, one with a dipole resonance at 520 nm and the other with a dipole resonance at 650 nm, placed in different media. Significant wavelength-dependent depolarization of scattered light from the silver nanoprisms suspended in water indicates strong interference of multiple surface plasmon resonant modes in the same particle. We use this depolarization as a probe of light scattering by the nanoprisms in a lipid solution due to the rejection of a polarized background scattering. Also, the silver nanoprisms were embedded in a polyvinyl alcohol polymer matrix and oriented by stretching the polymer/nanoprism nanocomposite films. We observe significantly increased linear dichroism in the region associated with the plasmonic in-plane dipole mode upon stretching. Additionally, there is a weaker linear dichroism in the region associated with out-of-plane modes, which vanish in the extinction spectrum of the stretched nanocomposite film.

Association of Previous Smoking Habit and Perceived Social Discrimination with the Risk of Multi-Drug Resistant Tuberculosis in Central Nepal

BACKGROUND

Multidrug-resistant tuberculosis (MDR TB) caused by Mycobacterium tuberculosis resistant to both Isoniazid and Rifampicin with or without resistant to other drug, is among the most alarming pandemic problem. The objectives of this study was to assess the risk factors of MDR TB in Central Nepal.

METHODS

A matched case control study was conducted among 186 cases of MDR TB and 372 non-MDR TB controls from central region of Nepal. Pretested questionnaires containing socio-economic, cultural & behavioral; environmental, biological and health service factors were used. Variables significant in bivariate analysis were entered in multiple regression models for further analysis.

RESULTS

After adjusting for confounders, previous smoking habit (aOR= 4.5,(95%CI(1.24-16.2)) (p=0.04), and perceived social discrimination (aOR=5.83,95%CI (1.77-19.71)) (P=0.021) independently predicted greater MDR TB risk.

CONCLUSIONS

Encouraging MDR TB cases for smoking cessation through awareness activities should be a priority. Stigma reduction programs should include the empowerment of patients and communities while promoting TBrelated research for further exploration into the risk factors of TB and associated stigma.

The spatial distribution of actin and mechanical cycle of myosin are different in right and left ventricles of healthy mouse hearts

The contraction of the right ventricle (RV) expels blood into the pulmonary circulation, and the contraction of the left ventricle (LV) pumps blood into the systemic circulation through the aorta. The respective afterloads imposed on the LV and RV by aortic and pulmonary artery pressures create very different mechanical requirements for the two ventricles. Indeed, differences have been observed in the contractile performance between left and right ventricular myocytes in dilated cardiomyopathy, in congestive heart failure, and in energy usage and speed of contraction at light loads in healthy hearts. In spite of these functional differences, it is commonly believed that the right and left ventricular muscles are identical because there were no differences in stress development, twitch duration, work performance, or power among the RV and LV in dogs. This report shows that on a mesoscopic scale [when only a few molecules are studied (here three to six molecules of actin) in ex vivo ventricular myofibrils], the two ventricles in rigor differ in the degree of orientational disorder of actin within in filaments and during contraction in the kinetics of the cross-bridge cycle.

Community attitudes towards leprosy affected persons in Pokhara municipality of western Nepal

BACKGROUND

Stigma is a social process of interpretation of an attribute. Leprosy has been seen as the epitome of stigmatization. The psychosocial impact a person has to bear in a society after the diagnosis weighs heavier than the physical afflictions it causes, which does not get cured with the mere medical treatment. There are various factors which construct the perception of stigma in both leprosy affected persons and unaffected persons. The main purpose of this study was to determine the level of perceived stigma and the risk factors contributing to it among community people living in ward 15, Pokhara municipality.

METHODS

Cross-sectional descriptive study among 281 community people above the age of 18 years was conducted. Two sets of questionnaire form with additional Explanatory Model Interview Catalogue (EMIC) for each individual were used.

RESULTS

Among 281 community people, the median score of perceived stigma was 12 while it ranged from 0-30. Ethnic groups, Brahmins, Dalits and minorities had highest perceived stigma score of 15 and above compared to the rest (p=0.001), community people living at the distance more than 2 km had highest perceived stigma score of 15 compared to those living closer to the hospital (p=0.019) and nuclear family had highest perceived stigma score of 15 compared to the joint family (p=0.014). People who lacked information on leprosy had higher score of perceived stigma compared to those who had information on leprosy (p=0.002).Similarly, those who perceived leprosy to be difficult to treat (p<0.001) and a severe disease (p<0.001) had highest score of perceived stigma.

CONCLUSIONS

Stigma in leprosy was found highly associated with the lack of information about leprosy and their perception in treatment and disease severity. Stigma reduction strategies should focus on health education, targeting to alleviate their perception about the disease with their active participation.

Factor VIII Bypassing Activity (FEIBA) assays: standardization and development of the 1st NIBSC Working Standard for FEIBA--results from a collaborative study

Factor-Eight-Inhibitor-Bypassing-Activity (FEIBA) is a bypassing-agent used to control spontaneous bleeding or cover surgical interventions in Haemophiliacs who develop neutralizing antibodies against FVIII/FIX. The market lot-release of FEIBA is dependent on specific clot-based assays, carried out by both the manufacturer and regulatory authorities, relative to manufacturer's in-house standards, which are produced on a small-scale and are replaced frequently. We sought to standardize the FEIBA assay by developing a FEIBA primary standard which would be internationally available in sufficiently large quantities, with a predicted lifetime of many years. A collaborative study involving the manufacturer and three regulatory authorities, was carried out in which a candidate material, sample B (06/172), was calibrated by assays relative to the manufacturer's in-house FEIBA standards (C and D). All laboratories used their routine validated methods (16 APTT-assays, 8 ACTIN-FS-assays and 27 DAPTTIN-assays). Intra-laboratory geometric coefficients of variation (GCVs) for candidate B ranged from 3% to 29% (GCVs <9% from majority of labs). Assessment of inter-laboratory variability gave overall GCV values of 6.9% and 4.4% relative to standards C and D, respectively, for all methods. There was good agreement in potency estimation between laboratories using each of the three methods, with the overall potencies by the three methods differing by less than 10% of the overall mean, giving an overall combined potency of 28.0 units per ampoule. All participants agreed that candidate B (06/172) be established as the 1st NIBSC Working Standard for FEIBA with an assigned potency of 28.0 units per ampoule, based on combined results for both methods, relative to either standard C or D.

Computed tomography scan in the evaluation of patients with stroke

Cerebrovascular accident is a frequent cause of death and disability in most parts of the globe. The incidence of cerebrovascular diseases increases with age and the number of strokes is projected to increase as the elderly population grows. This study was undertaken to determine the type of stroke and also to relate the risks factors associated with stroke. Hundred consecutive patients presenting with stroke in the emergency department / neurology clinic were subjected to computed tomography scan of the brain. Sixty – four patients had ischemic infarct and 36 had intracranial hemorrhage which included 2 patients with subarachnoid hemorrhage and 1 with underlying cavernous angioma. Ischemic stroke was thus commoner than hemorrhagic stroke. Previous infarct or lacunes were noted in 25 % of the patients presenting with stroke. Risk factors were present in most (77 %) of the patients presenting with stroke. Among the various risk factors, the single most common was smoking seen in 38 cases, followed by hypertension in 28 cases, obesity in 8 cases and diabetes in 3 cases. Twenty- one patients had multiple combinations of the above risk factors. Among the multiple risk factors, combination of alcohol and smoking was the commonest seen in 11 cases, followed by hypertension and obesity in 8 cases and alcohol with obesity in 2 cases. Change in lifestyle and eating habits may thus help reduce the incidence of stroke. Journal of College of Medical Sciences-Nepal,2012,Vol-8,No-2, 24-31 DOI: http://dx.doi.org/10.3126/jcmsn.v8i2.6834

Calibration of human coagulation factor VIII concentrate Ph. Eur. BRP Batch 4 for use in potency assays

The European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP) Batch 4 was established as an international common working standard for potency determination of human coagulation factor VIII (FVIII) preparations to replace the dwindling stocks of the BRP Batch 3, the current European standard. Similarly, stocks of the current World Health Organisation 7th International Standard (WHO 7th IS) were also running low. Therefore a project was jointly organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) and the National Institute for Biological Standards and Control (NIBSC, UK) in order to replace both standards concomitantly. The potency of the BRP Batch 4 was assigned during an international collaborative study involving 38 laboratories with reference to the WHO 7th IS and the BRP Batch 3. Four candidate materials, 2 plasma-derived (samples A and C) and 2 recombinant (samples B and D) have been evaluated, sample C being the specific candidate for the replacement of the BRP Batch 3. Participants were instructed to perform 8 independent assays following their own routine validated methods, by either the one-stage clotting assay or the chromogenic assay, or both. Laboratories returned 22 data sets for the clotting assay and 30 data sets for the chromogenic assay. This publication reports the results obtained with both assays but only the results of the chromogenic assay are highlighted in the conclusions, as it is the assay prescribed by the European Pharmacopoeia. Data were analysed separately for both assays. The consensus potency value was calculated as the unweighted geometric mean of the unweighted geometric means of each individual laboratory. For sample C, there was a significant difference in potency estimate between the chromogenic and the clotting assay. It was therefore not possible to reconcile both results. The chromogenic potencies however were in very good agreement being 10.4 IU/ampoule (n = 30), when assessed against both standards. The inter-laboratory geometric coefficient of variation (GCV) was 4.8 % and 7.1 % against the WHO 7th IS and the BRP Batch 3 respectively. The Ph. Eur. BRP Batch 4 is a freeze-dried, plasma-derived concentrate. The material was filled in approximately 20,000 ampoules and lyophilised. The final residual water content is 0.33 %. Based on accelerated degradation studies, the stability of the material is suitable for a reference preparation. The candidate Ph. Eur. BRP Batch 4 was adopted at the 136th session of the European Pharmacopoeia Commission in March 2010. The standard will be available from the EDQM with the catalogue number H0920000 upon exhaustion of the current batch.

Red grain botryomycosis due to Staphylococcus aureus--a novel case report

Staphylococcus aureus and some other bacteria are known to cause botryomycosis. These bacteria are known to produce yellowish-white soft grains. Only Actinomadura pelletieri is known to produce red grains. We report here a case of an intensely inflammatory type of botryomycosis. A 35-year-old male labourer presented with swelling, redness and multiple sinuses on his foot, of eight months duration. The purulent discharge contained bright red coloured grains, 0.5 to 1 mm in size, which were round to oval in shape. Gram-positive cocci were demonstrated in crushed granules and tissue sections. Culture yielded pure and heavy growth of Staphylococcus aureus . He responded very well to cefazolin. There is no other report of such red grain botryomycosis due to Staphylococcus aureus , available in literature. This is first case report of its kind in world literature.

A collaborative study to establish the 1st International Standard for factor XIII plasma

BACKGROUND

An international collaborative study, involving 23 laboratories, was carried out, under the auspices of the FXIII Standardization Working Party (SWP), to calibrate the 1st International Standard (IS) for factor XIII (FXIII) plasma.

METHODS

Potency estimates for the proposed candidate FXIII plasma (preparation Y: NIBSC code 02/206) were calculated relative to locally collected normal plasma pools (pool N), for both FXIII activity and antigen levels.

RESULTS

Estimates of FXIII activity potency for preparation Y showed good agreement between laboratories, with an interlaboratory geometric coefficient of variation (GCV) of 11.5% and a mean value of 0.91 U mL(-1). Furthermore, there was a negligible difference in potencies by two commercially available methods, the potencies differing only by approximately 1%. Estimates of FXIII antigen (A(2)B(2) complex) potency for preparation Y showed good agreement between laboratories, with an interlaboratory GCV of 16.3% and a mean value of 0.93 U mL(-1). Accelerated degradation studies showed that the proposed standard is very stable, with a predicted loss of activity (and antigen) per year of< 0.06% at the recommended storage temperature of -20 degrees C.

CONCLUSIONS

The suitability and potency of preparation Y were considered by the participants, members of the ISTH/SSC FXIII Subcommittee, the Scientific and Standardization Committee and the SWP. Following their approval, preparation Y was proposed to and accepted by the Expert Committee on Biological Standardization of the World Health Organization to be the 1st IS for FXIII plasma with an activity potency of 0.91 IU per ampoule and an antigen potency of 0.93 IU per ampoule.

A solvent/detergent-treated and 15-nm filtered factor VIII: a new safety standard for plasma-derived coagulation factor concentrates

BACKGROUND

Since the early 1990 s the Committee for Proprietary Medicinal Products has set the mandatory requirement that all manufacturing processes for blood products include two virus removal/inactivation steps that are complementary in their action.

OBJECTIVES

The objective was to develop a manufacturing process for factor VIII (FVIII) including two complementary steps of viral inactivation/elimination.

METHODS

A 35-15 nm nanofiltration step was added to a former FVIII manufacturing process that included solvent/detergent (S/D) treatment to generate a new FVIII concentrate called Factane. The impact of nanofiltration on the structural and functional characteristics of FVIII, as well as virus/transmissible spongiform encephalopathy reduction factors were assessed.

RESULTS

Using an innovative approach, FVIII was successfully nanofiltered at 35-15 nm, while the biological properties of the active substance were unmodified. FVIII coagulant and antigen content for Factane and previous S/D-treated FVIII (FVIII-LFB, commercialized as Facteur VIII-LFB) were comparable. The FVIII one-stage chromogenic and coagulant/antigen ratios confirmed that nanofiltered FVIII was not activated. After nanofiltration, the copurified von Willebrand factor (vWF) was reduced but vWF/FVIII binding properties were unaffected. Phospholipid binding and thrombin proteolysis studies displayed no differences between Factane and FVIII-LFB. The rate of factor Xa generation was slightly lower for Factane when compared to FVIII-LFB. Viral validation studies with different viruses showed no detectable virus in the filtrate.

CONCLUSIONS

Nanofiltration of FVIII at 15 nm is feasible despite the large molecular weight of FVIII and vWF. Nanofiltration has been proven to be highly effective at removing infectious agents while preserving the structural and functional integrity of FVIII.

A collaborative study to establish the 7th International Standard for Factor VIII Concentrate

A candidate concentrate, preparation N (99/678), was assayed and calibrated, as a potential replacement, against four established factor (F) VIII concentrate standards: the current WHO 6th International Standard (IS) (97/616), the previous 5th IS (88/640), the Mega 1 standard and Ph. Eur. BRP Batch 2 standard, in a collaborative study involving 38 laboratories. All laboratories were instructed to use the ISTH/SSC recommendations, including predilution of concentrates in FVIII-deficient plasma. Several laboratories performed more than one assay method and altogether there were 27 sets of assays with the one-stage method, 31 with the chromogenic method, and 18 with both methods. There was good agreement between laboratories using each of the two methods for comparison of preparation N against the four established standards, with overall potencies by one-stage and chromogenic methods differing only by less than 2%. However, there were significant differences in potencies relative to the different standards, ranging from 10.1 IU per ampoule against the Ph. Eur.BRP2 to 11.4 against the WHO 6th IS. Accelerated degradation studies showed that the proposed standard is very stable, with a predicted loss of activity per year of less than 0.001% at the recommended storage temperature of -20 degrees C. Various options for potency of preparation N were considered by the participants and by members of the ISTH/SSC FVIII/FIX Subcommittee. In November 2003, preparation N (NIBSC 99/678) was proposed to and accepted by the Expert Committee on Biological Standardization of the World Health Organization to be the 7th International Standard for Factor VIII Concentrate with an assigned potency of 11.0 IU per ampoule.

Biochemical recovery time scales in elderly patients with osteomalacia

Osteomalacia is not rare in the UK and climatically similar countries, particularly in elderly people and those of Asian descent. Overt clinical osteomalacia is usually treated with a loading dose of vitamin D, followed by a regular supplement. However, little is known of the time taken to reach a stable biochemical state after starting treatment. Such information would shed light on the duration of the bone remineralization phase and guide decisions on the length of follow-up. To address this we conducted a 2-year follow-up study of 42 patients (35 female, mean age 80.8 years) with biopsy proven osteomalacia treated with a standard replacement regimen and general nutritional support. Although normocalcaemia was attained within 4 weeks the mean values continued to rise, to a mid-range plateau at 52 weeks. The phosphate and alkaline phosphatase values also took at least a year to reach a stable mean, with a slight further trend towards the mid-range for the entire 104 weeks. The mean serum albumin also rose throughout the first 52 weeks, indicating an effective response to the general nutritional support measures. Our observations suggest that the dynamic relationship between calcium, phosphate and bone requires at least a year, and probably longer, to reach an equilibrium after treatment for osteomalacia in elderly patients. The findings emphasize the need for close medical and social follow-up in this clinical context.

Biochemical Recovery Time Scales in Elderly Patients with Osteomalacia

Osteomalacia is not rare in the UK and climatically similar countries, particularly in elderly people and those of Asian descent. Overt clinical osteomalacia is usually treated with a loading dose of vitamin D, followed by a regular supplement. However, little is known of the time taken to reach a stable biochemical state after starting treatment. Such information would shed light on the duration of the bone remineralization phase and guide decisions on the length of follow-up. To address this we conducted a 2-year follow-up study of 42 patients (35 female, mean age 80.8 years) with biopsy proven osteomalacia treated with a standard replacement regimen and general nutritional support.

Although normocalcaemia was attained within 4 weeks the mean values continued to rise, to a mid-range plateau at 52 weeks. The phosphate and alkaline phosphatase values also took at least a year to reach a stable mean, with a slight further trend towards the mid-range for the entire 104 weeks. The mean serum albumin also rose throughout the first 52 weeks, indicating an effective response to the general nutritional support measures.

Our observations suggest that the dynamic relationship between calcium, phosphate and bone requires at least a year, and probably longer, to reach an equilibrium after treatment for osteomalacia in elderly patients. The findings emphasize the need for close medical and social follow-up in this clinical context.

Variability in factor VIII concentrate measurement: results from SSC field collaborative studies

Seven 'field' collaborative studies on factor (F)VIII concentrate potency measurements were carried out, using local routine methodology, standards and calculation of results. Data from five of the 12 different concentrates studied are described in detail. These studies revealed that, for the intermediate-purity and the recombinant FVIII concentrates, one-stage potencies were significantly lower than chromogenic potencies, whilst for the two high-purity FVIII concentrates one-stage potencies were significantly greater than chromogenic potencies. On comparing predilution methods for the intermediate-purity concentrate, equivalent potencies were obtained using either buffer or FVIII-deficient plasma as prediluent. For the two high-purity and the recombinant concentrates, potencies obtained using buffer as prediluent were significantly greater and lower, respectively, than potencies obtained using FVIII-deficient plasma as prediluent. Interlaboratory variabilities were compared over all 12 concentrates studied and coefficients of variation (CVs) for one-stage assays were found to be much greater than for chromogenic assays. This was true for all concentrates except for the intermediate-purity concentrate and samples A and B from the first study, where the reverse was true. Furthermore, much better CVs were obtained when using FVIII-deficient plasma than when using buffer as prediluent, for all FVIII concentrates except for the intermediate-purity concentrate where the reverse was true, and sample B where CVs were equivalent. Overall, CVs were far worse than those obtained in controlled collaborative studies. Generally, however, CVs were better with chromogenic assays and predilution in FVIII-deficient plasma, as is recommended by the International Society on Thrombosis and Haemostasis/Scientific and Standardization Committee, particularly for higher purity and recombinant concentrates.

A modified thrombin generation test for the measurement of factor VIII concentrates

It has been well documented that there is an uncertainty over the true factor (F)VIII level in postinfusion samples due to assay discrepancies. The thrombin generation test (TGT) was used as a potentially more physiological approach to assess and compare FVIII concentrates. FVIII concentrates were added to artificial FVIII-deficient plasma. Thrombin generation was initiated by the addition of FIXa (14 nm), phospholipid and CaCl2. Thrombin was measured by subsampling into fibrinogen, and curves quantified as area under the curve (AUC) and time taken to half-maximum (t(1/2)max). Addition of one plasma-derived concentrate to as little as 0.005 IU mL-1 gave a normal AUC, but prolonged t(1/2)max. Increasing FVIII to 1 IU mL-1 had little effect on AUC, but did reduce the t(1/2)max to 64 s (normal 114 s). A range of plasma-derived and recombinant concentrates were tested at 1 IU mL-1; results were similar, except the B-domain deleted concentrate, which had the most rapid initial rate of thrombin generation (t(1/2)max 48 s, P < 0.05). Two hemophilic plasmas (< 0.01 IU mL-1) produced large amounts of thrombin (AUC 65% and 69%), although t(1/2)max was prolonged. Addition of a FVIII antibody abolished thrombin generation, indicating that these plasmas contained low levels of FVIII. Decreasing the FIXa concentration (0.2 nm) minimized thrombin generation in hemophilic plasma but not in normal plasma. These results indicate that FVIII < 0.01 IU mL-1 can generate significant quantities of thrombin depending upon the amount of FIXa present. The TGT could prove useful for patient monitoring in gene therapy and prophylaxis.

A collaborative study to establish the 6th International Standard for factor VIII concentrate

A study was carried out to replace the 5th WHO International Standard (IS) for factor VIII concentrate, because of depletion of stocks. Two candidate concentrates (X and Y) were assayed as potential replacements against the 5th IS for FVIII concentrate, in a collaborative study involving 33 laboratories. Collaborators were asked to use the ISTH/SSC recommendations, including pre-dilution of concentrates in FVIII deficient plasma in their assays. Several laboratories performed more than one assay method and altogether there were 21 sets of assays with the one-stage method, 6 with the two-stage method and 26 with the chromogenic method. There was good agreement between laboratories using each method for the comparison of concentrates X and Y against the 5th IS, but the overall potencies by one-stage and chromogenic methods each differed by approximately 5% from the overall mean, with the chromogenic potency approximately 10% higher than the one-stage. Inter-laboratory agreement was slightly better for concentrate Y than X, and stability studies indicated that Y was more stable than X. After considering all the information, together with comments from participants and from the FVIII/FIX Subcommittee of the ISTH/SSC, candidate Y (NIBSC code [97/616]), was proposed and accepted in October, 1998, by the Expert Committee on Biological Standardisation of the World Health Organisation to be the 6th International Standard for Factor VIII Concentrate with an assigned potency of 8.5 IU/ampoule.

Phospholipid binding of factor VIII in different therapeutic concentrates

Binding to anionic phospholipid (PL) is essential for the biological function of factor VIII (FVIII). We have developed a method to study the level of PL binding of FVIII in a variety of therapeutic concentrates, using the BIACORETM system which utilizes the Surface Plasmon Resonance (SPR) phenomenon. A HPA sensor chip was employed on to which synthetic phospholipid unilamellar vesicles were adsorbed to form a 3:1 phosphatidylcholine: phosphatidylserine lipid monolayer. Using this surface the interaction of unlabelled FVIII in concentrates was observed from which direct kinetic data (kon, koff and KD values) were obtained in real-time. Marked differences in the binding to PL, as measured by KD values, between different products were observed. These fell into three categories: two recombinant FVIII products showed high affinities for PL with KD values around 0. 05-0.14 nM; four high-purity plasma derived products, two prepared by monoclonal antibody and two prepared by ion-exchange chromatography, had 6-8-fold lower affinities, and two intermediate-purity products had 34-60-fold lower affinities with KD values in the nM region. Measurements of kon and koff values for each product showed that the differences in the KD values expressed were primarily due to the differences in their respective kon values, although the recombinant products showed changes in the koff values. The study showed that the assessment of binding to PL by FVIII in concentrates was possible without prior purification and gave KD values in the range reported previously for other methods. The difference between the products requires further investigation but may be partly due to other proteins present, in particular the content and quality of von Willebrand factor which is known to affect PL binding of FVIII.

Development of an ELISA for the quantification of fibrin in canine tumours

Fibrin is found in most solid tumours, and there is speculation regarding its role in tumour invasion and metastasis. An assay to quantitate fibrin levels in tissues would be a useful preliminary tool in assessing the above. Such an assay to quantitatively detect levels of fibrin in various types of canine tumour was developed. This procedure involved an ELISA using a monoclonal antibody (MAb 1H10) for canine fibrin as a capture antibody and a polyclonal antibody to human fibrinogen conjugated to horseradish peroxidase as the detection antibody. The ELISA is calibrated against known concentrations of freeze-fractured fibrin derived from clotted dog plasma. The assay takes 3.5 hours, and concentrations as low as 0.1 microg fibrin per milliliter of solubilised tumour can be readily detected. ELISA dilution curves for fibrin from various types of canine tumour were found to be parallel to the standard canine fibrin calibration curve. The intraassay and interassay variabilities of the assay gave coefficients of variation in the range of 2.4-4.5% and 7.2-7.8%, respectively, for the calibrator standard, in a concentration range of 0.1-10 microg/ml. Using this assay, we reported the levels of fibrin in three different types of malignant canine tissue.

Re-emergence of Vibrio cholerae O139 serogroup during 1998 in Nagpur (Maharashtra), India

In Nagpur, Maharashtra in 1993, V. cholerae serogroup O139 emerged as a novel epidemic strain. The decline in the isolation rate of this serogroup in subsequent year was followed by its re-emergence during 1998 indicating that this serotype requires careful monitoring.

Modification of factor VIII in therapeutic concentrates after virus inactivation by solvent-detergent and pasteurisation

The addition of a pasteurisation step to a solvent/detergent (SD) treated FVIII concentrate has recently resulted in enhanced inhibitor incidence in patients in Germany and Belgium. We have investigated the effect of virus inactivation procedures on FVIII function by preparing experimental concentrates from the same starting cryoprecipitate with the following procedures: none (N); dry heat (DH); pasteurisation (P); solvent/detergent (SD); solvent detergent + dry heat (SDDH); solvent detergent + pasteurisation (SDP). In addition, several clinical SD concentrates with and without pasteurisation were studied. There were no significant differences in fibrinogen and vWF content and in the ratio of one-stage/chromogenic FVIII activity among any of the samples studied. In thrombin proteolysis and FXa generation experiments, there were no differences in results on samples N, DH, P, and SDDH from those on sample SD. However sample SDP gave markedly different results from sample SD in the following respects: slower thrombin proteolysis (t(1/2) = 12.0 min vs 1.9 min); more rapid FXa generation (rate 2.5 times that of SD); enhanced phospholipid binding (K(D) = 3.89 x 10(-11) M vs 5.53 x 10(-10) M). Similar differences between SDP and SD were seen in the clinical samples. The observed changes in the FVIII activity occurred in combination with SD and pasteurisation, but not with either treatment alone. These results suggest that SDP treatment may enhance exposure of the phospholipid binding site in the C2 domain of FVIII, and since inhibitors to the SDP product are predominantly against C2, these findings could be relevant to the enhanced immunogenicity of the SDP product.

Discrepancies in potency assessment of recombinant FVIII concentrates

Results of assays of recombinant FVIII concentrates have been reviewed over a 10-year period. Initially there was wide variability between laboratories but this was minimised by the development of standardised assay methodology, in particular the use of haemophilic plasma for pre-dilution and 1% albumin in assay buffers. Using this standardised methodology and concentrate standards, there were no major differences in potency between one-stage, two-stage and chromogenic assays on the two full-length recombinant FVIII concentrates. However, using a plasma standard, the chromogenic method gave much higher potencies than the one-stage method on the same concentrates, and this explains a similar discrepancy found in patients' post-infusion samples after injection of recombinant concentrates. It is suggested that concentrate standards be used for such post-infusion samples in order to minimise this discrepancy.

Evaluation of the fibrin binding profile of two anti-fibrin monoclonal antibodies

Two anti-fibrin monoclonal antibodies, MAbs 1H10 and 5F3, raised to human freeze-fractured fibrin and thrombin-treated N-terminal disulphide knot (T-NDSK), respectively, were compared for epitope binding to various domains of the fibrinogen/fibrin moiety. Using plasmin-mediated fibrinogen digests, immunoblots showed that both MAbs crossreacted strongly with fragments X and Y, weakly with fragment-E and not at all with fragment D. Purified fragments D and E used in an ELISA confirmed that MAbs 1H10 and 5F3 cross-reacted in a dose-response fashion with the isolated fragment-E, while there was no reaction with fragment-D. The two MAbs were similarly shown to react with fibrin-derived fragment-E. Surface Plasmon Resonance (SPR) technology, employed to further evaluate the epitopes in fibrin, showed that MAb 1H10 had a higher affinity for fragment-E (KD = 8.04 x 10(-9) M) than MAb 5F3 (KD = 1.13 x 10(-8) M). Individual association and dissociation rate constants of 7.97 x 10(5) M-1s-1 and 3.97 x 10(-3)s-1, respectively, for MAb 1HAb 1H10, and 5.16 x 10(5) M-1s-1 and 3.62 x 10(-3)s-1, respectively, for MAb 5F3 were also obtained. A SPR inhibition assay confirmed that MAb 1H10 had a greater affinity for fragment-E than MAb 5F3. However individual isolated polypeptide chains of fibrinogen fragment E (E-A alpha, E-B beta, E-gamma) showed no reaction with the two antibodies in ELISA, immunoblot or SPR analysis procedures. Furthermore, SPR pair-wise epitope mapping analysis revealed that MAbs 1H10 and 5F3 have in fact distinct epitopes on fragment-E. These distinct epitopes appeared to be a conformational amalgam of linear sequences in two or three of the polypeptide chains of fragment-E, or distinct conformational epitopes on one of the three subunit chains alone.

Interaction of heparin with fibrinogen using surface plasmon resonance technology: investigation of heparin binding site on fibrinogen

Heparin is widely used as an antithrombotic drug, having excellent anticoagulant properties. However in certain clinical situations heparin's efficacy seems to be somewhat limited. Despite the administration of heparin there is a high incidence of reocclusion of coronary arteries following thrombolytic therapy, and it has been observed that a significant number of patients receiving heparin treatment still exhibit thrombus extension. Although it is well established that the in vitro and in vivo anticoagulant activities of heparin is mediated via the potentiation of the major coagulation inhibitor, antithrombin III (ATIII), some in vivo antithrombotic mechanisms are not fully understood. There is poor correlation between the anticoagulant activity of heparin as measured by in vitro assays and their in vivo antithrombotic efficacy. This may be due to heparin being targeted to many blood constituents whose resultant activities on the coagulation system have not been measured as yet. The antithrombotic activity of heparin as well as the pathogenesis of bleeding complications during heparin treatment cannot be completely explained by the inhibition of blood coagulation factors. Platelet dysfunction and acceleration of fibrinolytic process have been implicated as additional factors involved. Recently a number of reports have suggested that the inhibition of the antithrombotic activity of heparin in these clinical situations may be due to the interaction of heparin with other plasma proteins specifically with fibrin(ogen) present in the thrombus. Despite the possible pathophysiological significance of heparin-fibrin(ogen) interaction, little is known about the physicochemical aspects of this reaction. In this study an attempt was made to locate where heparin binds to fibrin(ogen), using various isolated structural domains from the plasmin-mediated digests of fibrinogen and the individual chains of fibrinogen. The BIALITE system (Pharmacia Biosensor AB, Uppsala, Sweden) was employed for such a study. This utilises the Surface Plasmon Resonance (SPR) phenomenon and allows a direct quantitative analysis of the label-free molecular interaction, in real-time, from which association and dissociation rate constants can readily be obtained.

Effects of early plasmin digests of fibrinogen on isometric tension development in isolated rings of rat pulmonary artery

The purpose of the study was to determine the effects of early plasmin-mediated digests of rat fibrinogen on the vascular tone of rat pulmonary artery in order to compare with reported vasoactive effects of high levels of isolated human peptides in various rat vascular beds. Isometric tension was monitored in isolated rings of rat pulmonary artery precontracted with phenylephrine (4 x 10(-8) mol). Fibrinogen degradation products (FgDPs) were produced by digestion of rat fibrinogen with plasmin to 1, 2, 3 and 60 minutes whereupon the digestion was stopped by addition of Trasylol. These FgDPs were added to the tissue bath to achieve final concentrations of 6.7, 13.3, 26.7 and 53.3 micrograms/mL i.e. values similar to those found in vivo during thrombolytic therapy for myocardial infarction. Results were expressed as a percentage of a maximal contraction elicited in each ring in response to phenylephrine (10(-5) M). The early FgDP fractions, at these pathophysiological concentrations, did not induce significant change in isometric tension in the isolated pulmonary arterial rings (P > 0.05, ANOVA).

Characterisation of the chains of human fibrinogen isolated by perfusion chromatography using fibrin specific monoclonal antibodies

In order to study the epitopes on fibrin to which monoclonal antibodies are directed, we required pure individual polypeptide chains of human fibrinogen in milligram quantities. High purity chains of human fibrinogen were rapidly obtained, in under 3 minutes, by the novel procedure of reversed-phase perfusion chromatography and these chains were subjected to immunological characterisation using monoclonal antibodies specific to the individual chains. Cross-reactivity against these antibodies in both immunoblotting and enzyme linked immunospecific assay (ELISA) procedures showed that these isolated fibrinogen chains were of high purity and retained high immunoreactivity. These chains were employed to initiate studies to define the epitopes in fibrin to which four fibrin specific monoclonal antibodies, B10, A11, 5F3 and 1H10 are targeted. Two of these antibodies, B10 and A11, were shown to be directed to a linear sequence on the A alpha chain, although the binding profiles for the two antibodies suggested that different epitopes may be involved for each of these two antibodies. MAbs, 1H10 and 5F3, however, did not bind to any of the three fibrinogen chains, suggesting that conformational epitopes in fibrin are likely to be involved in the binding of these two antibodies to fibrin.

Ultra-rapid preparation of milligram quantities of the purified polypeptide chains of human fibrinogen

In order to study the epitopes in fibrin towards which monoclonal antibodies are directed we needed the pure individual polypeptide chains of human fibrinogen in reasonable quantity. We report here a simplified, rapid method of separation of high-purity human fibrinogen chains. Following reduction and S-carboxymethylation of human fibrinogen, the sample was injected directly onto a column of the polymeric reversed-phase perfusion packing POROS 20-R2, and the chains were completely resolved in less than 3 min at a flow-rate of 10 ml/min. The capacity was equivalent to that of a similar sized conventional silica-based column. However the throughput was approximately five to ten times as high. The column was durable and robust in day-to-day use.