Double Diffusion Technique Research Articles

Cardiac Fatigue in Male Athletes with Exercise-Induced Pulmonary Impairments After a Very Long-Distance Triathlon.

Prolonged strenuous exercise can transiently decrease cardiac function. Other studies have identified three major exercise-induced pulmonary changes: bronchoconstriction, dynamic hyperinflation and pulmonary oedema with reduced alveolar-capillary membrane diffusing capacity. This study investigated whether athletes with one of these pulmonary dysfunctions following a very long-distance triathlon exhibit similar cardiac alterations as those without dysfunctions. Sixty trained male triathletes (age 39 ± 9years) underwent baseline and post-race assessments, including echocardiography (with standard, 2D-strain and myocardial work assessments), spirometry and double-diffusion technique to evaluate alveolar-capillary membrane diffusing capacity for carbon monoxide (DMCO). Cardiac function in athletes with exercise-induced bronchoconstriction (> 10% decrease FEV1), dynamic hyperinflation (> 10% decrease inspiratory capacity) or impaired diffusion capacity (> 20% decrease DMCO/alveolar volume) were compared with those without these dysfunctions. The race lasted 14h 20min ± 1h 26min. Both systolic and diastolic cardiac functions declined post-race. Post-race, 18% of athletes had bronchoconstriction, 58% dynamic hyperinflation and 40% impaired diffusing capacity. Right and left ventricular standard and 2D-strain parameters were similar before the race in all subgroups and changed similarly post-race, except E/E', which decreased in the bronchoconstriction subgroup and increased in those with diffusion impairment. Global constructive work decreased by ~ 19% post-race (2302 ± 226 versus 1869 ± 328mmHg%, P < 0.001), more pronounced in athletes with diffusion impairment compared with others (- 26 ± 13 versus - 15 ± 9%, P = 0.001) and positively correlated with DMCO/alveolar volume reduction. After a very long-distance triathlon, bronchoconstriction and hyperinflation were not associated with significant cardiac changes, whereas impaired alveolar-capillary membrane diffusing capacity was associated with a more significant decline in myocardial function. These findings highlight the complex relationship between pulmonary gas exchange abnormalities and cardiac fatigue following prolonged strenuous exercise.

Two is better than one: the double diffusion technique in classifying heart failure.

Heart failure (HF) is a chronic condition in which the heart does not pump enough blood to meet the body's demands. Diffusing capacity of the lung for nitric oxide (DLNO) and carbon monoxide (DLCO) may be used to classify patients with HF, as DLNO and DLCO are lung function measurements that reflect pulmonary gas exchange. Our objectives were to determine 1) if DLNO added to DLCO testing predicts HF better than DLCO alone and 2) whether the binary classification of HF is better when DLNO z-scores are combined with DLCO z-scores than using DLCO z-scores alone. This was a retrospective secondary data analysis in 140 New York Heart Association Class II HF patients (ejection fraction <40%) and 50 patients without HF. z-scores for DLNO, DLCO and DLNO+DLCO were created from reference equations from three articles. The model with the lowest Bayesian Information Criterion was the best predictive model. Binary HF classification was evaluated with the Matthews Correlation Coefficient (MCC). The top two of 12 models were combined z-score models. The highest MCC (0.51) was from combined z-score models. At most, only 32% of the variance in the odds of having HF was explained by combined z-scores. Combined z-scores explained 32% of the variation in the likelihood of an individual having HF, which was higher than models using DLNO or DLCO z-scores alone. Combined z-score models had a moderate ability to classify patients with HF. We recommend using the NO-CO double diffusion technique to assess gas exchange impairment in those suspected of HF.

Pisciculture and Fish Parts as Non-clinical Source of CTX-M and TEM Extended Spectrum Beta-lactamases Producing Escherichia coli in Southeastern Nigeria

Background and Objectives: Antimicrobial agent use in pisciculture exerts a selective pressure, resulting in a reservoirs of extended spectrum beta-lactamase producing Escherichia coli in the aquatic environment. Here we screened pisciculture and fish parts as non-clinical source of CTX-M and TEM Extended Spectrum Beta-lactamases (ESBL) producing Escherichia coli in Southeastern Nigeria Methodology: A total of sixty fish parts [fish gills, body part and intestinal swab samples] were collected from pisciculture farm A, C, F and G within Abakaliki metropolis. The samples were bacteriologically analyzed using standard microbiological techniques for isolation and identification. ESBL enzymes were phenotypically detected in E. coli, isolates using the double disk diffusion technique. The presence of TEM and CTX-M genes was determined by polymerase chain reaction using specific primers. Results: Escherichia coli and Extended spectrum beta-lactamase producing Escherichia coli accounted for overall occurrence rate of 27(45.0 %) and 17(28.3 %) respectively. There was no statistically significant difference in the occurrence of Escherichia coli and ESBL-E. coli among the different samples P&gt;0.05. The presence of TEM and CTX-M gene 80 % and 100 % respectively were confirmed among the isolates. Conclusion: Our findings reports the presence of ESBL gene in pisciculture and fish parts and it is important in understanding the mechanism of resistance operating in these common pathogens, which are also endemic in most pisciculture area. Strict rules and monitoring/surveillance of antimicrobial agent used in pisciculture activities combined with food safety training of farmer owners/breeders on various aspects of good hygiene practices are strongly recommended.

Distribution of blaTEM Gene among Escherichia Coli Strains Isolated from Different Clinical Samples in Erbil City

Background: Emerging antibiotic resistance and Extended-Spectrum Beta-Lactamase (ESBL) producing Escherichia coli causing different nosocomial infections are rapidly increasing at alarming levels and it poses a major health burden in the 21st century globally. Objective: The aim of this study is to determine the distribution of blaTEM gene ESBLproducing E. coli from clinical specimens in different hospitals in Erbil city. Methods: A total of 200 samples were collected from (sputum, urine, wound) from patients attended public hospitals in Erbil city. The isolation and identification of Escherichia coliand antimicrobial susceptibilitywere performed by using Vitek 2 compact -lactamase production in E.coli was confirmed by using both Double disk diffusion and Standard disk diffusion techniques. Moreover, PCR technique was used for genotypic detection of an ESBL gene blaTEMaccording to the standard protocol. Results: Out of 200 samples 60(30%) of E. coli isolates and the highest rate of E. coli isolates were obtained from the urine samples (20%) and the lowest number was isolated from sputum specimens (2.5%). The ESBL-producing Escherichia coli isolates were detected using double disk synergy test (76.7%) in comparison to standard disk diffusion test (80%). Genotypic screening results confirmed that all ESBL-producing E. coli isolates (66.7%) were carried blaTEM gene (700 bp) in clinical specimens (50% urine, 13.33% wound and 3.33% sputum). All ESBL-positive E. coli isolates showed high rates of susceptibility to Carbapenems antibiotic group including Imipenem (83.3%), Meropenem (81.7%), and Ertapenem (80.0%). Conclusions: -lactamase gene in ESBL-producing E. coli observed in this study for the first time is considered as alarming because there is a limited treatment options remained for infections. Attempts to reduce the dissemination of multi-drug resistant E. coli through compliance with strict hospital infection control and prevention standards are imperative. Findings of this study may help clinicians selecting appropriate antimicrobial therapy in patients with different infections caused by ESBLproducing E. coli.

Week to week variability of pulmonary capillary blood volume and alveolar membrane diffusing capacity in patients with heart failure

BackgroundAlveolar-capillary membrane diffusing capacity for carbon monoxide (DMCO) and pulmonary capillary volume (Vcap) can be estimated by the multi-step Roughton and Foster (RF, original method from 1957) or the single-step NO–CO double diffusion technique (developed in the 1980s). The latter method implies inherent assumptions. We sought to determine which combination of the alveolar membrane diffusing capacity for nitric oxide (DMNO) to DMCO ratio, an specific conductance of the blood for NO (θNO) and CO (θCO) gave the lowest week-to-week variability in patients with heart failure. Methods44 heart failure patients underwent DMCO and Vcap measurements on three occasions over a ten-week period using both RF and double dilution NO-CO techniques. ResultsWhen using the double diffusing method and applying θNO = infinity, the smallest week-to-week coefficient of variation for DMCO was 10 %. Conversely, the RF method derived DMCO had a much greater week-to-week variability (2x higher coefficient of variation) than the DMCO derived via the NO-CO double dilution technique. The DMCO derived from the double diffusion technique most closely matched the DMCO from the RF method when θNO = infinity and DMCO = DLNO/2.42. The Vcap measured week-to-week was unreliable regardless of the method or constants used. ConclusionsIn heart failure patients, the week-to-week DMCO variability was lowest when using the single-step NO-CO technique. DMCO obtained from double diffusion most closely matched the RF DMCO when DMCO/2.42 and θNO = infinity. Vcap estimation was unreliable with either method.

Polar Structure Formation in Solid Solution of Strontium-Substituted Fluorapatite–Gelatin Composites: From Structural and Morphogenetic Aspects to Pyroelectric Properties

Strontium substituted apatite-(CaF)-gelatin composites have been synthesized within a gelatin gel using the double diffusion technique. All experimental parameters were kept constant while systemat...

Antibiotic resistance pattern of Salmonella species isolated from Typhoid patients in Jigawa state, Nigeria

This study was designed to determine the antibiotic resistance pattern of Salmonella spp. isolated from clinical samples of symptomatic and asymptomatic typhoid patients, selected from some hospitals in Jigawa State, Nigeria. Four hundred bacterial isolates were recovered from these samples, were identified as; Salmonella typhimurium, S. enteritidis, S. typhi, S. paratyphi A, and S. paratyphi B using microgen biochemical system, according to the standard techniques. The antibiogram of all these Salmonella spp. were carried out using standard oxoid disc of different antibiotics. Double disc diffusion technique was employed to determine the isolates’ capacity to produce β-lactamase. Results showed 5(1.25%), 0(0.0%), 0(0.0%) of the samples collected were positive for extended spectrum β-lactamases (ESBL), AmpC β-lactamase, and Metallo β-lactamases (MBL), respectively. The antibiogram profile of the isolates showed that 100% of these isolates are susceptible to Imipenem, only 3% exhibited resistance to ceftriaxone, whereas 7% demonstrated resistance to ciprofloxacin. To the best of our knowledge, this the first study of this kind in the Jigawa state, especially on these Salmonella spp. The study concluded that β-lactamases with the capacity of conferring multidrug resistance were recorded in Salmonella spp. isolated from patients in several hospitals of Jigawa State, Nigeria.

Phase Stability and Morphology of Gel Grown Crystals: The Case of CdCl2-bpp Polymeric System

A phenomenological study is carried out on a complex two-component diffusion-reacting system in gel, that is, the Cd-1,3-bis(4-pyridyl)propane (Cd-bpp) coordination polymer. The latter can exist in three solid forms, which exploit a 1:1 correspondence among the Cd/bpp ratio, the crystal structure and the crystal morphology (1/2: bipyramids; 2/3: needles; 1/3: plates). The aim was to clarify the role of key physicochemical variables (reactant concentrations, composition of the solvent and density of the transport medium) in determining the chemical nature and the morphology of the final crystallization products. The gel method was tested in a variety of different crystallization configurations, including single and double diffusion techniques. The density of the gel primarily affects the morphology of the synthesized crystals, with denser media favouring the needle-like 2/3 Cd-bpp species and diluted ones the 1/2 Cd-bpp bipyramidal one. However, higher densities of the gel are generally associated to strained crystals. The solvent composition is also important, as for example the 1/2 Cd-bpp bipyramids require at least a minimum amount of ethanol to appear. We demonstrated that in gel the strict “equality” stoichiometric criteria for metal-to-ligand ratios can be sometimes eluded, as non–equilibrium concentrations can be locally attained. In this respect, the crystallization geometry was proven to act as a key tool to influence the crystallization output, as it determines the direction and magnitude of the concentration gradients. Finally, the use of U tubes to perform one-pot screenings of a large part of the crystallization space is discussed.

Targeted siRNA Nanoparticles for Mammary Carcinoma Therapy.

Non-viral, polymeric-based, siRNA nanoparticles (NPs) have been proposed as promising gene delivery systems. Encapsulating siRNA in targeted NPs could confer improved biological stability, extended half-life, enhanced permeability, effective tumor accumulation, and therapy. In this work, a peptide derived from apolipoprotein B100 (ApoB-P), the protein moiety of low-density lipoprotein, was used to target siRNA-loaded PEGylated NPs to the extracellular matrix/proteoglycans (ECM/PGs) of a mammary carcinoma tumor. siRNA against osteopontin (siOPN), a protein involved in breast cancer development and progression, was encapsulated into PEGylated poly(d,l-lactic-co-glycolic acid) (PLGA) NPs using the double emulsion solvent diffusion technique. The NPs obtained possessed desired physicochemical properties including ~200 nm size, a neutral surface charge, and high siOPN loading of ~5 µg/mg. ApoB-P-targeted NPs exhibited both enhanced binding to isolated ECM and internalization by MDA-MB-231 human mammary carcinoma cells, in comparison to non-targeted NPs. Increased accumulation of the targeted NPs was achieved in the primary mammary tumor of mice xenografted with MDA-MB-231 mammary carcinoma cells as well as in the lungs, one of the main sites affected by metastases. siOPN NPs treatment resulted in significant inhibition of tumor growth (similar bioactivity of both formulations), accompanied with significant reduction of OPN mRNA levels (~40% knockdown of mRNA levels). We demonstrated that targeted NPs possessed enhanced tumor accumulation with increased therapeutic potential in mice models of mammary carcinoma.

Use of antigenic composition to differentiate among Rhizoctonia solani isolates from flax

Rhizoctonia solani is an plant pathogenic fungus with a wide host range and worldwide distribution. Double diffusion technique was used to differentiate among Rhizoctonia solani isolates from flax. In this technique, antisera of isolate 23 (AG-2) and isolate 24 (AG-4) reacted against antigens of 24 isolates belonging to AG-2 and Ag-4. The antiserum of isolate 23 (AG-2) was insensitive to differentiate among the isolates of AG-2, while it was highly sensitive to differentiate among some isolates of AG-4. The antiserum of isolate 24 (AG-4) was highly sensitive as a serotaxonomic tool to differentiate among AG-2 and AG-4, while it was of limited value in differentiating among isolates of within each AG.

English

The aim of the study was to characterize the antimicrobial components of Lactobacillus paracasei KSI. In the study, a L. paracasei KSI strain was isolated and identified from aguamiel using a 16S rRNA, hsp, recA and rpoBgenes sequencing. The antimicrobial capacity of the L. paracasei strain KSI was determined by agar double layer diffusion technique, while the antagonistic activity of the cell-free extract (E-KSI) was evaluated by agar well diffusion method against different bacterial strains; it demonstrated a wide spectrum of inhibition. Likewise, E-KSI showed stability at different temperatures and digestive enzymes; its activity was lost at pH>5. Subsequently, E-KSI was concentrated (10x) by evaporation increasing its antagonistic effect. Antagonism tests by thin-layer chromatography (TLC)–bioautography of the E-KSI 10x showed the presence of more than one active substances different from lactic acid, possibly of the bacteriocin type. Some of these substances were recovered by extractions with ethyl ether, ethyl acetate and n-butanol respectively. Finally, we evaluated them using antagonism tests by minimum inhibitory concentration (MIC) and microdilution. L. paracaseistrain KSI generates substances with antibacterial activity having a wide spectrum of inhibition; it is a promising alternative to future biotechnological applications. The strain of L. paracasei KSI as well as the antimicrobial components that it generates has important antagonistic properties, making them an interesting biotechnological alternative to be used as probiotic or a safe functional food. Key words: Lactobacillus, antimicrobials, probiotics, biotechnology, food safety.

Use of Serological Interactions to Differentiate between Trichoderma harzianum and Trichoderma longbrachiatum Isolated from Cotton Roots

Double diffusion (DD) and immunoelectrophoresis (IE) techniques were used to differentiate among Trichoderma isolates. Each of T. longbrachiatum and T. harzianum isolates tended to group together based on their antigenic composition, which indicated a remarkable overall serological similarity among isolates of each species. However, the serological differences among the isolates did not always reflect the taxonomic differences because some isolates of T. longbrachiatum and T. harzianum showed considerable serological similarity. Thus, DD and IE were not useful techniques in identification of Trichoderma isolates.

Injectable deferoxamine nanoparticles loaded chitosan-hyaluronic acid coacervate hydrogel for therapeutic angiogenesis

In this study, an injectable chitosan-hyaluronic acid (CS-HA) based hydrogel was designed incorporating pro-angiogenic molecule, deferoxamine loaded PLGA nanoparticles (DFO NPs), for enhancing angiogenesis. DFO-NPs were prepared by double emulsion solvent diffusion technique and characterized for their physicochemical properties. The DLS and SEM analysis showed an average particle size of 220±71nm with spherical morphology and the encapsulation efficiency was found to be 30±5%. An ECM mimicking chitosan-hyaluronic acid (CS-HA) coacervate hydrogel was prepared. Both free DFO and DFO NPs were entrapped into the prepared CS-HA composite hydrogel. The hydrogels were characterized by SEM, FTIR and Rheology. Addition of DFO NPs did not affect the injectablility and flowability of developed hydrogels. In vitro DFO release from the prepared composite hydrogels showed controlled release over a period of 10days. Both the hydrogel systems showed excellent cyto-compatability and good cell proliferation for rASCs as well as HUVECs. The DFO and DFO NPs loaded composite hydrogels revealed effective tube formation in comparison with control hydrogels without DFO and DFO NPs. The in vivo angiogenic evaluation of the free DFO and DFO NPs (0.025%w/w) loaded composite hydrogels were studied by injecting the developed hydrogel subcutaneously into mice for 2–4 weeks. The DFO NPs loaded composite hydrogel had enhanced neovascularization when compared to control gels. Thus, the developed DFO NPs loaded composite hydrogel could potentially be used for therapeutic angiogenesis.

Polymeric nanoparticles of siRNA prepared by a double-emulsion solvent-diffusion technique: Physicochemical properties, toxicity, biodistribution and efficacy in a mammary carcinoma mice model

siRNA-loaded nanoparticles (NPs) administered systemically can overcome the poor stability and rapid elimination of free double-stranded RNA in circulation, resulting in increased tumor accumulation and efficacy. siRNA against osteopontin (siOPN), a protein involved in breast cancer development, was encapsulated in poly(D,L-lactic-co-glycolic acid) NPs by a double emulsion solvent diffusion (DESD) technique. We also compared the effect of polyethylenimine (PEI) molecular weight (800Da and 25kDa), used as the counter-ion for siRNA complexation, on the physicochemical properties of the NPs, cytotoxicity, and cellular uptake. NPs prepared by the DESD technique were obtained at the desired size (∼170nm) using both types of PEIs, and were characterized with a neutral surface charge, high encapsulation yield (up to ∼60%), siOPN concentration of 5.6-8.4μg/mg, stability in physiologic conditions invitro and invivo, and long-term shelf-life stability (> 3 years). The NPs prepared using both PEIs exhibited no cytotoxicity in primary smooth muscle culture, and no detrimental effect on mice liver enzymes following their IV administration. Following cellular uptake and biodistribution studies, the therapeutic potential of the NPs was demonstrated by a significant decrease of tumor progression and size in an ectopic xenograft model of mammary carcinoma in mice.

Antimicrobial susceptibility of extended-spectrum beta-lactamase producing &lt;i&gt;Enterobacteriaceae&lt;/i&gt; causing urinary tract infections in Ouagadougou, Burkina Faso

Objective: To determine the frequency of extended-spectrum beta lactamase producing Enterobacteriaceae (ESBL) and other antibioticsresistant bacteria in urinary tract isolates.Study Design: prospective and experimental study.Methodology: Place and duration of study :YalgadoOuedraogo University Hospital Center, Charles De Gaulle Pediatric Hospital Center, Saint Camille Hospital and National Public Health Laboratory, Ouagadougou, from November 2014 to October 2015.AllEnterobacteriaceaestrains isolated from urinary samples of patients were identifiedusing API 20E chemical gallery (BioMerieux, France). All strains were subjected to an array of 14 antibiotics to study their drug susceptibility by using Kirby- Baeurdisk diffusion method. Detection of ESBL was carried out by double disk diffusion technique. Statistical analysis was performed by Microsoft Excel and Anova one-way GrapPad Prism version 5.01. Chi-square (χ2) test was used to determine significance. A p˂ 0.05was considered to be statistically significant.Results: A total of 324 isolates of Enterobacteriaceae were identified during the study period, including211(65%) E. coli, 75 (23%)Klebsiella spp., 18 (6%) Enterobacter spp., 11 (3%)Proteus spp., 5 (2%) Citrobacter spp., Serratia spp. 3 (1%).All the clinical isolates were susceptible to imipenem. Resistance to amikacinwas 14% (45/324); gentamicin 54% (175/324); tobramycin 58% (187/324); nalidixic acid 72% (234/324),ciprofloxacin 63% (204/324) and to cotrimoxazole 83% (269/324).The overall rate of the EBSL producing strains was 35% (114/324). Their susceptibility to antibiotics was (imipenem,amikacin, cefoxitin and fosfomycin) 100% (114/114), 93% (106/114), 74% (84/114) and 84% (96/114) respectively. ESBL positivity within individual organism group was highest inEscherichia coli 64% (73/324) followed byKlebsiellaspp. 28% (32/324), Enterobacterspp. 3% (4/324), Proteus spp. and Citrobacterspp. 2% (2/324).Conclusion: The results showeda high frequency of ESBL producing Enterobacteriaceae, especially Escherichia coli and Klebsiellaspp. The data points to theneed of routine detection and surveillance of ESBL producing bacteria in Burkina Faso.Keywords: Antimicrobial susceptibility, Enterobacteriaceae, Urine, Burkina Faso

Development of zolmitriptan loaded PLGA/poloxamer nanoparticles for migraine using quality by design approach

The purpose of this investigation was to develop Poly (D,L Lactide-co-Glycolide) (PLGA)/poloxamer nanoparticles (NPs) of the hydrophilic drug Zolmitriptan using quality-by-design approach for brain targeting. Randomized 24 full factorial design was employed to achieve the critical quality attributes of minimized particle size and maximized encapsulation efficiency. The PLGA/poloxamer NPs were fabricated using modified double emulsion solvent diffusion technique and particle size varied from 165.4–245.4nm, encapsulation efficiency was in the range of 48.96–95.97% and percent cumulative drug release varied from 43.32 to 100%. The optimized nanoparticles were characterized by FTIR spectroscopy and powder X-ray diffraction technique which indicated the loading of drug in NPs without any chemical interactions between drug and the excipients. The uniform and spherical shape of the particles was affirmed from TEM analysis. The in-vivo studies for determination of brain uptake potential demonstrated a 14.13 fold increase in drug delivered to brain from the NPs as compared to the free drug. The pharmacodynamic studies involving Swiss albino mice further confirmed successful delivery of drug to brain circumventing the blood brain barrier, through significantly enhanced anti-migraine potential. This investigation thus presents the suitability of zolmitriptan loaded PLGA/poloxamer NPs in brain targeting for the efficient treatment of migraine.

Electrospun cellulose acetate supported Ag@AgCl composites with facet-dependent photocatalytic properties on degradation of organic dyes under visible-light irradiation

Electrospun cellulose acetate (CA) membrane was employed as a support that provided sites for AgCl crystals in situ growth. The Ag@AgCl crystals on electrospun CA composites with exposed {100} and {111} facets were fabricated at room temperature by a double diffusion technique. The crystal structure, morphology, composition, and absorption light ability of CA supported Ag@AgCl were characterized utilizing X-ray powder diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflection-infrared intensity (ATR-IR), X-ray photoelectron spectroscopy measurements (XPS), energy dispersive spectrometer (EDS) and ultraviolet–visible (UV–vis) diffuse reflectance spectra, respectively. The photocatalytic activity of the catalysts was evaluated using methyl orange (MO) as a target. The CA supported cubic Ag@AgCl catalyst exhibited much higher catalytic activity than octahedral catalyst in terms of the degradation of MO under visible light. The 10mg CA based cubes could completely degrade MO (10mgL−1) in 160min. The photocatalyst still exhibited a good catalytic ability after three times.

Explorer, Nobel laureate, astrobiologist: things you never knew about Barry Blumberg.

Baruch S. “Barry” Blumberg, winner of the 1976 Nobel Prize in Physiology or Medicine and founding director of the NASA Astrobiology Institute (NAI), passed away suddenly of a heart attack at age 85 on April 5, 2011, during a conference at Ames Research Center. That Barry spent his last day conceptualizing an International Research Park on the Moon befits the unflagging curiosity that characterized his life in general and his scientific career in particular. In this paper I trace Barry's scientific career, including his early formative years and the unexpected path that led to the Nobel Prize. I also show that Barry's perspective and approach to science in general made astrobiology a natural area to attract his attention after he had retired from medical research. Indeed, his priorities as NAI director reflect directly things that were important to him throughout his career.

The Australia (Hepatitis-associated) Antigen

INTRODUCTION The accidental discovery of the Australia antigen (HAA) in 1963 by Blumberg and his coworkers is a classical example of biomedical serendipity. Its recognition not only stimulated a substantial amount of research into viral hepatitis, thereby adding considerably to our knowledge about this important disease, but has had far-reaching implications in the understanding of several other hepatic and systemic diseases. Indeed, its discovery may well be seen in the future to have been the all-important breakthrough in attempts at culture of the virus as a means of vaccine preparation for future prophylactic usage. THE DISCOVERY OF THE ANTIGEN Blumberg, a cytogeneticist working in the Philadelphia Institute for Cancer Research, was conducting a systematic study of the serum of patients who had received multiple blood transfusions. Using a technique of double diffusion in agar gel (Ouchterlony method) he searched for precipitating antibodies to inherited donor serum protein antigens, particularly those to low density betalipoproteins. A precipitating antibody was identified in the serum of a haemophiliac patient which reacted with an antigen which was quite dissimilar from lipoprotein antigens. This antigen was present in the serum of an Australian aborigine, and the term Australia antigen was coined (1, 2, 3,). This antigen is almost certainly identical to Prince’s SH antigen (4), and to avoid confusion the term hepatitis-associated antigen (HAA) is now considered by many to be more appropriate (5).

Barium hydrogen phosphate/gelatin composites versus gelatin-free barium hydrogen phosphate: Synthesis and characterization of properties

Recently, attention has been spent on crystal growth of phosphate compounds in gels for studying the mechanism of in vitro crystallization processes.Here, we present a gel-based approach for the synthesis of barium hydrogen phosphate (BHP) crystals using single and double diffusion techniques in gelatin. The composite crystals were compared with analytical grade BHP powder, single and polycrystalline BHP materials using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), scanning pyroelectric microscopy (SPEM), optical microscopy (OM), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). FTIR spectra showed surface adsorption of gelatin molecules by using BHP stacked sheets due to CH2 stretching, CH2 bending and amide I vibrations are found in a gelatin content of about 2% determined by dissolution. SEM shows various crystal morphologies of the BHP/gelatin composites forming bundled micro-flakes to irregular bundled needles and spheres different from gel-free crystals. The variety in morphology depends on the ion concentration, pH of gel as well as the method of crystal growth. SPEM investigation of BHP/gelatin aggregates revealed polar domains showing alteration of the polarization. Moreover, BHP/gelatin composite crystals showed a higher thermal stability in comparison with analytical grade BHP or/and BHP single crystals due to strong interactions between gelatin and BHP. The XRD diffraction analysis demonstrated that the single and double diffusion techniques in gelatin led to the formation of orthorhombic BHP. This study demonstrates that gelatin is a useful high molecular weight biomacromolecule for controlling the crystallization of a composite material by producing a variety of morphological forms.