Plasma ctDNA RAS status selects patients for anti-EGFR treatment rechallenge in metastatic colorectal cancer: a meta-analysis.

BACKGROUND: Recently one randomized trial and several phase II studies underscored that patients with metastatic colorectal cancer who progressed after an initial clinical benefit from anti-epidermal growth factor receptor (EGFR) treatment may further benefit from rechallenge with anti-EGFR therapy. Testing circulating tumor DNA (ctDNA) RAS status prior to anti-EGFR rechallenge seems a promising non-invasive method to predict and monitor response to anti-EGFR readministration. AIM: To assess the capability of liquid biopsy ctDNA in exploring RAS status and in predicting outcome of metastatic colorectal cancer patients treated with anti-EGFR monoclonal antibody rechallenge. MATERIALS AND METHODS: Systematic review of literature and meta-analysis of the available evidence. RESULTS: Data from four studies involving 117 patients were available. All patients harbored RAS wild type tumors and derived benefit from first line anti-EGFR therapy. Of these, 65 underwent plasma ctDNA before anti-EGFR treatment rechallenge and were eligible for analyses: 35 patients had RAS wild type ctDNA, and 30 RAS mutated, indicating that 46% of patients underwent RAS status conversion after primary anti-EGFR therapy. Anti-EGFR rechallenge among patients with plasma ctDNA RAS wild type status was associated with a consistent benefit in progression free survival (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.22-0.70; p = 0.001; I2 = 0) and overall survival (HR 0.37, 95% CI 0.16-0.85; p = 0.02; I2 = 74%) when compared to its use among patients with plasma ctDNA RAS mutation. Patients with plasma ctDNA RAS wild type profile also performed statistically better in term of disease control rate, risk for disease progression at 3 and 6 months, and risk for death at 6 and 12 months. CONCLUSION: RAS status assessment continues to be useful in predicting benefit for anti-EGFR treatment.

Resolution of HLA-B*44:02:01G, -DRB1*14:01:01G and -DQB1*03:01:01G reveals a high allelic variability among 12 European populations.

Within the framework of the EU-funded HLA-NET action, an analysis of three G-group alleles, HLA-B*44:02:01G, DRB1*14:01:01G and DQB1*03:01:01G, was undertaken in 12 European populations. Ambiguities were resolved by polymerase chain reaction-sequence-specific amplification (PCR-SSP) or PCR-sequence-based typing (PCR-SBT) in a total of 5095 individuals. The results of the DRB1*14:01/14:54 ambiguity showed high relative ratios (24-53%) of DRB1*14:01 in Bulgarians, Croatians, Greeks, Italians and Slovenians, contrasting with low ratios (6-13%) in Austrians, Finnish, French, Hungarians, Norwegians and Swiss. Resolution of the B*44:02/44:27 ambiguity showed that B*44:27 had a high relative ratio in Slovenians (25.5%) and Bulgarians (37%) and low in French and Swiss (0.02-1%), and was not observed in Greeks and Italians. The highest relative ratio of DQB1*03:19 was found in Portuguese (11%), by contrast with low ratios (0-3%) in the other five populations. Analysis of the A, B, DRB1 phenotypes and family-derived haplotypes in 1719 and 403 individuals positive for either HLA-B*44:02G or DRB1*14:01G ambiguities, respectively, showed some preferential associations, such as A*26∼DRB1*14:01, B*35∼DRB1*14:01, B*38∼DRB1*14:01 and B*44:27∼DRB1*16. Because these ambiguities are located outside the peptide-binding site, they may not be recognized by alloreactive T-cells. However, because of strong linkage disequilibrium (LD), the DRB1*14:01 vs DRB1*14:54 and the B*44:02 vs B*44:27 mismatches are associated to DRB3-, and C-mismatches, respectively. These results are informative for algorithms searching unrelated hematopoietic stem cell donors. For B*44:27-positive patients, searches are expected to be more successful when requesting donors from Southeastern-European ancestry. Furthermore, the introduction of human leukocyte antigen (HLA)-typing strategies that allow resolving exon 4 (for class I) and exon 3 (for class II) polymorphisms can be expected to contribute significantly to population genetics studies.

Preserved levels of uninvolved immunoglobulins are independently associated with favorable outcome in patients with symptomatic multiple myeloma.

Suppression of uninvolved immunoglobulins is common in multiple myeloma (MM) but the prognostic significance of this phenomenon has not been assessed. We evaluated the prognostic significance of the preservation of uninvolved immunoglobulins in 1755 consecutive, unselected, patients with newly diagnosed, symptomatic MM with pre-therapy immunoglobulin levels measured by nephelometry. Suppression of at least one uninvolved immunoglobulin was observed in 87% of patients and was more common in patients with immunoglobulin A myeloma, those aged over 65 years, in patients with advanced-International Staging System (ISS) stage, extensive-bone marrow infiltration, anemia, low platelet counts, high levels of serum M-monoclonal protein or renal dysfunction. Patients with preserved immunoglobulins had a better survival than patients with suppressed immunoglobulins (median survival 55 vs 41.5 months, P<0.001). In multivariate analysis, preservation of uninvolved immunoglobulins was independently associated with better survival (hazard ratio: 0.781, 95% confidence interval: 0.618-0.987, P=0.039); irrespective of the treatment. In a subset of 500 patients, which were strictly followed for disease progression, preservation of uninvolved immunoglobulins was associated with a significantly longer progression-free survival (60 vs 25 months, P<0.001), independently of other common prognostic factors. In conclusion, preservation of uninvolved immunoglobulins in newly diagnosed patients with symptomatic MM was independently associated with long term disease control and improved survival.

Comparative evaluation of xenobiotics in human and dietary milk: persistent organic pollutants and mycotoxins.

Publications produced over the past 20 years regarding the concentration of xenobiotics in human and dietary milk were evaluated, focusing primarily on persistent organic pollutants (e.g. polychlorinated biphenyls, flame retardants), pesticides (e.g organochlorine) and mycotoxins. In general, countries of low industrialization rate present low levels of dietary milk contamination with dioxins compared to those with high rate of industrialization. According to published data, the most common persistent organic pollutants detected in breast and dietary milk are dichlorodiphenyltrichloroethane compounds, hexachlorocyclohexane, and hexachlorobenzene. Even though the potential risks of persistent organic pollutants in human milk have been acknowledged, the beneficial effect of breastfeeding as the optimal food source for newborn babies should not be disregarded. Especially when sharing information with the general public, it should be made clear that the presence of dioxins and persistent organic pollutants in human milk is not an indication for avoiding breastfeeding. The implications of xenobiotics in human and dietary milk is a matter of growing importance and warrants future work given its important health effects.

The role of novel agents on the reversibility of renal impairment in newly diagnosed symptomatic patients with multiple myeloma.

The role of thalidomide, bortezomib and lenalidomide in multiple myeloma patients presenting with renal impairment was evaluated in 133 consecutive newly diagnosed patients who were treated with a novel agent-based regimen. A significant improvement of renal function (renalPR (renal partial response)) was observed in 77% of patients treated with bortezomib, in 55% with thalidomide and in 43% with lenalidomide (P=0.011). In multivariate analysis, bortezomib-based therapy was independently associated with a higher probability of renal response compared with thalidomide- or lenalidomide-based therapy. Other important variables included eGFR (estimated glomerular filtration rate) ≥30 ml/min, age ≤65 years and myeloma response. Patients treated with bortezomib achieved at least renalPR in a median of 1.34 months vs 2.7 months for thalidomide and >6 months for lenalidomide-treated patients (P=0.028). In multivariate analysis bortezomib-based therapy, higher doses of dexamethasone (≥160 mg during the first month of treatment), an eGFR ≥30 ml/min and age ≤65 years were independently associated with shorter time to renal response. In conclusion, bortezomib-based therapies may be more appropriate for the initial management of patients with myeloma-related renal failure; however, thalidomide and lenalidomide are also associated with significant probability of improvement of their renal function.

Extensive bone marrow infiltration and abnormal free light chain ratio identifies patients with asymptomatic myeloma at high risk for progression to symptomatic disease.

Asymptomatic multiple myeloma (AMM) is characterized by a constant risk of progression to symptomatic myeloma. To evaluate previously recognized risk factors and to identify high-risk features we analyzed 96 patients with AMM and at least 18 months of follow-up. The progression rate at 1,2, and 3 years was 8%, 15% and 26%, respectively, and the projected 5-year progression rate was 38%. Extensive bone marrow (BM) infiltration, abnormal free light chain (FLC) ratio and serum monoclonal (M)-protein ≥ 3 gr/dl were the most significant factors for progression, whereas the type of heavy (IgG vs IgA) or light chain or immunoparesis of the uninvolved immunoglobulins were not. Abnormal marrow signal of magnetic resonance imaging of the spine was associated with a significant risk of progression (median 15 months, P=0.001). Extensive BM infiltration ≥ 60% (hazard ratio, HR: 13.7, P<0.001) and FLC ratio ≥ 100 (HR: 9, P=0.003) independently identified a 'very high-risk' group, which included 12.5% of patients with AMM and who progressed ≤ 18 months from initial diagnosis. Development of anemia and/or lytic bone lesions were the most common features of symptomatic progression. In conclusion, there is a subgroup of patients who have a substantial risk of progression to symptomatic disease that can be detected at diagnosis (either by extensive BM infiltration ≥ 60% or FLC ratio ≥ 100) and may be considered for immediate treatment.

Strategies to work with HLA data in human populations for histocompatibility, clinical transplantation, epidemiology and population genetics: HLA-NET methodological recommendations.

HLA-NET (a European COST Action) aims at networking researchers working in bone marrow transplantation, epidemiology and population genetics to improve the molecular characterization of the HLA genetic diversity of human populations, with an expected strong impact on both public health and fundamental research. Such improvements involve finding consensual strategies to characterize human populations and samples and report HLA molecular typings and ambiguities; proposing user-friendly access to databases and computer tools and defining minimal requirements related to ethical aspects. The overall outcome is the provision of population genetic characterizations and comparisons in a standard way by all interested laboratories. This article reports the recommendations of four working groups (WG1-4) of the HLA-NET network at the mid-term of its activities. WG1 (Population definitions and sampling strategies for population genetics' analyses) recommends avoiding outdated racial classifications and population names (e.g. 'Caucasian') and using instead geographic and/or cultural (e.g. linguistic) criteria to describe human populations (e.g. 'pan-European'). A standard 'HLA-NET POPULATION DATA QUESTIONNAIRE' has been finalized and is available for the whole HLA community. WG2 (HLA typing standards for population genetics analyses) recommends retaining maximal information when reporting HLA typing results. Rather than using the National Marrow Donor Program coding system, all ambiguities should be provided by listing all allele pairs required to explain each genotype, according to the formats proposed in 'HLA-NET GUIDELINES FOR REPORTING HLA TYPINGS'. The group also suggests taking into account a preliminary list of alleles defined by polymorphisms outside the peptide-binding sites that may affect population genetic statistics because of significant frequencies. WG3 (Bioinformatic strategies for HLA population data storage and analysis) recommends the use of programs capable of dealing with ambiguous data, such as the 'gene[rate]' computer tools to estimate frequencies, test for Hardy-Weinberg equilibrium and selective neutrality on data containing any number and kind of ambiguities. WG4 (Ethical issues) proposes to adopt thorough general principles for any HLA population study to ensure that it conforms to (inter)national legislation or recommendations/guidelines. All HLA-NET guidelines and tools are available through its website http://hla-net.eu.

CT60 single-nucleotide polymorphism as a surrogate marker for donor lymphocyte infusion outcome after allogeneic cell transplantation for acute leukemia.

The benefit of survival at the expense of new GVHD after DLI for acute leukemia following human allogeneic hematopoietic cell transplantation (allo-HCT) remains a matter of controversy. The detection of biological markers predicting this outcome would be an enormous breakthrough. The purpose of this study was the analysis of CT60 single-nucleotide polymorphism (SNP) of the CTLA-4 T-regulatory gene as a surrogate marker for DLI outcome in this difficult setting. Using Pyrosequencing, we genotyped the alleles of the CT60 SNP of 79 DLI donors and correlated them with the post-DLI outcome of their matching recipients. The presence of a donor 'AA' or 'AG' CT60 genotype vs a 'GG' genotype was an independent factor for remaining in complete chimerism/remission post-DLI (odds ratio (OR) 2.61 vs 0.42, respectively, P=0.05). Further, in cases with evident post-DLI allo-reactivity the importance of an 'AA' or 'AG' vs a 'GG' genotype gained significance for ongoing complete chimerism (OR 4.35 vs 0.32, P=0.03). Neither alterations in cumulative DLI dose nor any other clinical parameter significantly weakened the importance of CT60 SNP. Our results provide evidence for the necessity of genotyping CT60 SNP prior to DLI administration in patients with acute leukemia.

Two- and three-layer tablet drug delivery systems for oral sustained release of soluble and poorly soluble drugs.

BACKGROUND: Multilayer tablets are gaining importance in oral sustained drug delivery. They consist of an active matrix core and one or more layers applied during tableting which may act as barriers and regulate drug release. OBJECTIVE: To examine the release performance of two model drugs, diclofenac sodium and furosemide, from two- and three-layer drug delivery systems using as carriers hydrophilic swellable polymers, namely, Metolose, Polyox, Xantham gum, and an erodible material Gantrez. RESULTS AND DISCUSSION: All prepared formulations demonstrated sustained release profiles. They also indicated that the carrier characteristics (particularly swelling-expansion, erosion-dissolution) and drug solubility in combination with tablet structure considerably influenced the performance of examined formulations as well as their mode and mechanisms of release. In general our findings show that the differences in drug release between the two- and three-layer tablets are small as it appears that two-layer tablets exhibit a slightly higher release. Because of its greater erosion Gantrez formulations displayed faster release relative to Xantham gum, as did Metolose formulations compared to Polyox formulations. A faster release rate was also noted with diclofenac formulations compared to those of furosemide because of diclofenac's higher solubility mainly seen at early time period. CONCLUSIONS: All three-layer Gantrez tablets containing either diclofenac or furosemide and the two-layer furosemide formulation demonstrated a biphasic release. The above indicate that both structures may be used successfully for sustained release drug delivery. In addition the use of multilayer tablets, consisting of materials with suitable properties, may result in modulation of drug release.

HLA-DQA1*0505 sharing and killer immunoglobulin-like receptors in sub fertile couples: report from the 15th International Histocompatibility Workshop.

This aim of the study was to investigate whether human leukocyte antigen (HLA)-DQA1*0505 sharing or the maternal killer immunoglobulin-like receptor (KIR) repertoire is associated with recurrent spontaneous abortion (RSA) or repeated implantation failure (RIF). The study included 224 couples with RSA, 61 couples with RIF, 182 fertile couples, and 10 couples with successful in vitro fertilization and embryo transfer (IVF)/ET at first cycle. HLA-DQA1*0505 typing using polymerase chain reaction-sequence-specific oligonucleotide (PCR-SSO) was performed in 185 RSA (117 with alloimmune abnormalities and 68 of autoimmune etiology), 61 RIF and 182 control couples, and KIR genotyping using polymerase chain reaction-sequence-specific primer (PCR-SSP) in 167 RSA and 55 RIF cases as well as 46 RSA and 10 IVF controls. No differences in DQA1*0505 sharing were found between patients and controls. In RSA and RIF women, the ratio of inhibitory to activating KIRs was slightly lower (1.53 and 1.85 vs 2.03 in controls). The analysis of maternal inhKIR and fetal HLA-C molecule pairs showed that the 'less inhibiting' combination KIR2DL3-C1 was found in higher percentage in subfertile (mainly RIF) than in fertile couples. In contrast, the percentage of cases possessing the 'strong inhibiting' combination KIR2DL1-C2 was lower in the RSA and RIF groups in comparison with that in the control groups (17.36% vs 23.91 and 16.36% vs 40%, respectively). In women with >or= 6 implantation failures, the KIR2DL1-C2 combination was not found in any of them (P = 0.0014), and the KIR2DL3-C1 combination was not found in the control IVF group. The results oppose the suggestion that increased HLA-DQA1*0505 sharing predispose to RSA or RIF. The KIR2DL3-C1 combination (or lack of the KIR2DL1-C2 one) is associated with implantation failure.

Takayasu arteritis: epidemiological, clinical, and immunogenetic features in Greece.

OBJECTIVE: Takayasu arteritis (TA) is an uncommon disease with clinical heterogeneity across different ethnic groups. We aimed to evaluate the epidemiological, clinical, and immuno-genetic features of TA in Greece. METHODS: Demographic, clinical, laboratory, angiographic, and therapeutic data of 42 patients from 4 large referral centers were retrieved. Serology and Human Lymphocyte Antigen (HLA) typing was performed in 22 patients. RESULTS: We studied 37 women and 5 men with a median age of 31 years at disease onset. Median delay in diagnosis was 24 months and median follow-up was 47 months (range 0-178). Constitutional or musculoskeletal symptoms were present in 86%, especially early in the disease course. Vascular findings were universal with reduced or absent pulse being the most common manifestation (98%). Hypertension was frequent (78%). Extensive disease prevailed and stenotic lesions were more common than aneurysms (95% vs. 40%). Erythrocyte sedimentation rate and C-reactive protein showed modest correlation with disease activity. HLA-B52 was expressed by 37% of the patients vs. 2.4% of the controls (p<0.001). Glucocorticoids and cytotoxic agents were used in most patients with remission rates of 83%. A total of 42 surgical procedures were performed with success rates of 87%. CONCLUSION: TA in Greece clinically and epidemiologically resembles the pattern of disease in Japan and the Western hemisphere. There is considerable delay in diagnosis, which may partially reflect failure to recognize a rare disease. New surrogate markers are needed to assess disease activity. Glucocorticoids are the cornerstone of treatment and cytotoxic drugs are frequently used as steroid sparing agents.

14th International HLA and Immunogenetics Workshop: report from the reproductive immunology component.

The aim of the study was to investigate whether human leukocyte antigen (HLA) allele sharing between partners or the maternal killer immunoglobulin-like receptor (KIR) repertoire is associated with recurrent spontaneous abortion (RSA) and repeated implantation failure after in vitro fertilization (IVF)/embryo transfer. From a total population of 158 RSA couples, 40 couples with repeated implantation failures (IVF) and 81 control couples, reported by five different laboratories, analysis was performed for (a) HLA sharing in 50 RSA, 31 IVF and 31 control couples, (b) DQA1*0505 sharing/homozygosity among partners in 108 RSA, 40 IVF and 36 control couples, and (c) the women's KIR repertoire in 46 RSA, 26 IVF and 36 control wives. RSA couples were divided into alloimmune aborter (RSAallo) and autoimmune aborter (RSAauto). The results oppose to the suggestion that increased HLA sharing per se or a limited maternal KIR repertoire predisposes to RSA or IVF failure. However, the observation of a slightly higher percentage of DQA1*0505 sharing in the RSAauto and the IVF group needs further investigation. The ratio of inhibitory to activating KIR (actKIR) was slightly lower in RSAallo and IVF women (1.9 vs 2.6 in controls), while in a high percentage of these women, the standard receptors of the KIR A haplotype were combined with actKIR/s of the haplotype B (66.6% and 45.4% vs 20% and 15.3% in RSAauto and control groups). This may suggest a possible involvement of actKIRs in embryo implantation and the maintenance of pregnancy and also requires further investigation.

Design and evaluation of a dry coated drug delivery system with an impermeable cup, swellable top layer and pulsatile release.

In this investigation a novel oral pulsatile drug delivery system based on a core-in-cup dry coated tablet, where the core tablet surrounded on the bottom and circumference wall with inactive material, is proposed. The system consists of three different parts, a core tablet, containing the active ingredient, an impermeable outer shell and a top cover layer-barrier of a soluble polymer. The core contained either diclofenac sodium or ketoprofen as model drugs. The impermeable coating cup consisted of cellulose acetate propionate and the top cover layer of hydrophilic swellable materials, such as polyethylene oxide, sodium alginate or sodium carboxymethyl cellulose. The effect of the core, the polymer characteristics and quantity at the top cover layer, on the lag time and drug release was investigated. The results show that the system release of the drug after a certain lag time generally due to the erosion of the top cover layer. The quantity of the material, its characteristics (viscosity, swelling, gel layer thickness) and the drug solubility was found to modify lag time and drug release. The lag time increased when the quantity of top layer increased, whereas drug release decreased. The use of sodium carboxymethyl cellulose resulted in the greatest swelling, gel thickness and lag time, but the lowest drug release from the system. Polyethylene oxide showed an intermediate behaviour while, the sodium alginate exhibited the smallest swelling, gel thickness and the shortest lag time, but the fastest release. These findings suggest that drug delivery can be controlled by manipulation of these formulations.

Lack of the appropriate natural killer cell inhibitory receptors in women with spontaneous abortion.

Previous studies have revealed that women with unexplained recurrent spontaneous abortions have a limited repertoire of inhibitory KI receptors (inhKIRs) and that the inhKIRs they possess do not have specificity for the human leukocyte antigen (HLA)-Cw molecules that would be expressed on trophoblast. We sought to confirm these findings by direct definition of maternal inhKIR and trophoblastic HLA-Cw allotypes on the placental material of spontaneously missed pregnancies. The study included 30 women undergoing vacuum uterine curettage for first-trimester missed pregnancy (group A; n = 15) or for elective termination of normal pregnancy (group C, n = 15). DNA extracted from isolated decidual and trophoblastic cells was used for molecular detection of maternal inhKIRs (2DL1, 2DL2, 2DL3) and fetal HLA-Cw alleles, respectively. The results revealed that in the group of women who experienced abortion, 60% did not have the full repertoire of three inhKIRs (group A vs group C; p = 0.006); that in five of 15 patients (none in the controls), no epitope matching existed between maternal inhKIRs and trophoblastic HLA-Cw alleles (group A vs group C; p = 0.01); and that more cases were found with limited epitope matching (less than three inhKIRs with specificity for fetal HLA-Cw alleles). The results provide additional evidence that in some cases of spontaneous abortions, the women lack the appropriate inhKIRs to interact with the HLA-Cw molecules on trophoblasts and to deliver signals to inhibit natural killer cell activation and protect the embryo.

Minor histocompatibility antigen HA-1 and HPA-5 polymorphisms in HLA-identical related bone marrow transplantation.

The minor histocompatibility antigens (mHags), HA-1 and HPA-5, are immunogenic alloantigens shown to be responsible for graft-versus-host disease (GVHD) in HLA-identical bone marrow transplantation. Both antigens have two known alleles each, resulting in a single amino acid polymorphism. The HA-1H allele encodes histidine, whereas the HA-1R allele encodes arginine. The HPA-5b (Br(a)) allele encodes lysine, whereas the HPA-5a (Br(b)) encodes glutamic acid. In this study, 49 bone marrow transplant recipients and their genetically related HLA-identical donors were evaluated for the presence of HA-1, whereas 39 recipients, different from the abovementioned ones, and their HLA-identical siblings were analyzed for the presence of HPA-5. The frequencies of the two alleles of HA-1 in the recipient population were HA-1R = 0.663 and HA-1H = 0.336. In the donor population, the respective frequencies were 0.704 and 0.296. Seven donors (14.5%) were mismatched with the recipients for HA-1H. In contrast, the frequencies of the two alleles of HPA-5 in the recipient population were HPA-5a = 0.859 and HPA-5b = 0.141; whereas, among donors, they were 0.820 and 0.180, respectively. Five donors (12.8%) were found to be mismatched with their recipients for HPA-5. These results provide insight into the polymorphism of mH antigens based on the study of their frequencies in bone marrow transplant recipients and their genetically HLA-identical siblings, an endeavor that is essential to investigate the presence of HA-1 and HPA-5 mHags.

Swelling properties of various polymers used in controlled release systems.

The effect of powder packing and porosity of specimens on the swelling properties of polymeric materials was studied, in various swelling liquids, such as distilled water and 0.1 N hydrochloric acid solution. Capsules, tablets and films of hydroxypropyl methylcellulose, poly(ethylene oxide) and sodium alginate were prepared, and their weight uptake after immersion into the above solutions was recorded as a function of time, in order to assess the swelling process. Measurements of some characteristics of the as-received powders were also performed in an attempt to classify the specimens prepared according to their porosity. Within the experimental conditions of this work, it was shown that the porosity of polymeric specimens is a dominant factor that controls their swelling behaviour. Increased porosity leads to fast initial rates of weight uptake and high extent of equilibrium swelling. On the other hand, dissolution and possible degradation of polymers susceptible to acid hydrolysis results in some variations from the above mentioned behaviour. With respect to the application in controlled release systems, the overall delivery rate from a polymeric specimen is expected to be a function of both swelling and disintegration characteristics of a specimen, and therefore, the weight uptake can be considered a measure of the release only in the case of polymers with low water solubility and increased stability to hydrolysis.

Swelling properties of various polymers used in controlled release systems.

The effect of powder packing and porosity of specimens on the swelling properties of polymeric materials was studied, in various swelling liquids, such as distilled water and 0.1 N hydrochloric acid solution. Capsules, tablets and films of hydroxypropyl methylcellulose, poly(ethylene oxide) and sodium alginate were prepared and their weight uptake after immersion into the above solutions was recorded as a function of time, in order to assess the swelling process. Measurements of some characteristics of the as received powders were also performed as an attempt to classify the specimens prepared according to their porosity. Within the experimental conditions of this work, it was shown that the porosity of polymeric specimens is a dominant factor that controls their swelling behaviour. Increased porosity leads to fast initial rates of weight uptake and high extent of equilibrium swelling. On the other hand, dissolution and possible degradation of polymers susceptible to acid hydrolysis, results in some variations from the above-mentioned behaviour. With respect to the application in controlled release systems, the overall delivery rate from a polymeric specimen is expected to be a function of both swelling and disintegration characteristics of a specimen and, therefore, the weight uptake can be considered a measure of the release only in the case of polymers with low water solubility and increased stability to hydrolysis.

Polymers for use in controlled release systems: the effect of surfactants on their swelling properties.

The effect of an ampholytic surfactant on the swelling properties of polymeric materials was studied, using various swelling liquids. Tablets were prepared consisting of hydroxypropyl methylcellulose, poly(oxyethylene) and sodium alginate. Tego betain was the non-ionic surfactant used as an additive in a series of samples made of the above polymers. Those tablets were immersed in distilled water, phosphate buffer and 0.1 N HCl, and their weight uptake was recorded as a function of time, in order to assess the swelling process. Measurements of the contact angle of the above systems were also carried out for estimating their wetting properties. The results of this study showed a selectivity among polymers, surfactant and surrounding liquid. Clearly, an enhancement of the swelling capacity of hydroxypropyl methylcellulose tablets due to the surfactant was recorded. An unclear effect was observed in the case of poly(oxyethylene), whereas for sodium alginate, the dominant factor is its water solubility that controls swelling behaviour.

Evaluation of high molecular weight poly(oxyethylene) (Polyox) polymer: studies of flow properties and release rates of furosemide and captopril from controlled-release hard gelatin capsules.

The powder characteristics and the effect of the molecular weight of polymers as diluents on the release rate of furosemide and captopril from hard gelatin capsules were evaluated. The high molecular weight polymers studied were poly(oxyethylene) homopolymers (Polyox), with molecular weight ranging from 4,000,000 to 7,000,000. Powder characteristics suggested good flowability for these materials and predicted capsule fill weight uniformity. Swelling experiments showed a very high degree of swelling for these materials in both gastric and buffer solution. These polymers can sustain the release rate of both water-soluble and insoluble drugs from drug delivery systems. The low molecular weight polymers have a less pronounced sustained-release effect compared to the high molecular weight polymer material (i.e., those with 7,000,000 molecular weight). An increase in the content of polymer results in a decrease in the release rate of the drug. The solubility of the drugs clearly influenced the release rate. Release kinetics were evaluated and appeared to be influenced by the molecular weight of the polymer, the solubility of drug, and the ratio of the drug to polymer in the capsule. Bimodal release kinetics were exhibited by a number of furosemide formulations (i.e., F5 and F8).

MHC class I and class II phenotype, gene, and haplotype frequencies in Greeks using molecular typing data.

In the present study, DNA typing for HLA-A, C, B, DRB1, DRB3, DRB4, DRB5, DQA1, DQB1, and DPB1 was performed for 246 healthy, unrelated Greek volunteers of 20-59 years of age. Phenotype, genotype frequencies, Hardy-Weinberg equilibrium fit, and 3-locus haplotype frequencies for HLA-A, C, B, HLA-A, B, DRB1, HLA-DRB1, DQA1, DQB1, and HLA-DRB1, DQB1, DPB1 were calculated. Furthermore, linkage disequilibrium, deltas, relative deltas and p-values for significance of the deltas were defined. The population studied is in Hardy-Weinberg equilibrium, and many MHC haplotypes are in linkage disequilibrium. The most frequent specificities were HLA-A*02 (phenotype frequency = 44.3%) followed by HLA-A*24 (27.2%), HLA-B*51 (28.5%), HLA-B*18 (26.8%) and HLA-B*35 (26.4%) and HLA-Cw*04 (30.1%) and HLA-Cw*12 (26.8%). The most frequent MHC class II alleles were HLA-DRB1*1104 (34.1%), HLA-DQB1*0301 (54.5%) and HLA-DPB1*0401 with a phenotype frequency of 59.8%. The most prominent HLA-A, C, B haplotypes were HLA-A*24, Cw*04, B*35, and HLA-A*02, Cw*04, B*35, each of them observed in 21/246 individuals. The most frequent HLA-A, B, DRB1 haplotype was HLA-A*02, B*18, DRB1*1104 seen in 20/246 individuals, while the haplotype HLA-DRB1*1104, DQB1*0301, DPB1*0401 was found in 49/246 individuals. Finally, the haplotype DRB1*1104, DQA1*0501, DQB1*0301 was observed in 83/246 individuals. These results can be used for the estimation of the probability of finding a suitable haplotypically identical related or unrelated stem cell donor for patients of Greek ancestry. In addition, they can be used for HLA and disease association studies, genetic distance studies in the Balkan and Mediterranean area, paternity cases, and matching probability calculations for the optimal allocation of kidneys in Greece.