Plastic photodegradation under simulated marine conditions

Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation can induce photodegradation, but its importance in determining the longevity of floating plastic remains unconstrained. Here, we measured photodegradation rates of different plastic types slightly larger than microplastics (virgin polymers and floating plastic debris) under simulated marine conditions. UV irradiation caused all plastic types to leach dissolved organic carbon, and to a lesser degree carbon dioxide, carbon monoxide, methane, and other hydrocarbon gases. The release of photodegradation products translates to degradation rates of 1.7-2.3 % yr^-1 of the tested plastic particles normalized to conditions as found in the subtropical surface ocean. Modelling the accumulation of floating plastic debris, our results show that solar UV radiation could already have degraded 7 to 22 % of all floating plastic that has ever been released to the sea.

A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber

Methods that unambiguously prove microbial plastic degradation and allow for quantification of degradation rates are necessary to constrain the influence of microbial degradation on the marine plastic budget. We developed an assay based on stable isotope tracer techniques to determine microbial plastic mineralization rates in liquid medium on a lab scale. For the experiments, ¹³C-labeled polyethylene (¹³C-PE) particles (irradiated with UV-light to mimic exposure of floating plastic to sunlight) were incubated in liquid medium with Rhodococcus ruber as a model organism for proof of principle. The transfer of ¹³C from ¹³C-PE into the gaseous and dissolved CO₂ pools translated to microbially mediated mineralization rates of up to 1.2 % yr^-1 of the added PE. After incubation, we also found highly ¹³C-enriched membrane fatty acids of R. ruber including compounds involved in cellular stress responses. We demonstrated that isotope tracer techniques are a valuable tool to detect and quantify microbial plastic degradation.

[Umbilical cord hematopoietic progenitor cells bank]

Transplantation of hematopoietic progenitor cells (HPC) from bone marrow and mobilized peripheral blood is a standard therapy in malignant and non malignant diseases. The lack of suitable donors is an important limitation. The discovery that umbilical cord blood (CB) contains high numbers of HPC that can be used as an alternative source for allogeneic stem cell transplantation led ITMO to establish BANCEL, the first Argentine and Latinoamerican experience of its kind. The blood remaining in the umbilical cord and in the placenta was requested from women who were in the last quarter of pregnancy. An informed consent together with a medical record focused on family disease was completed. Out of 65 donations, 55 (85%) were collected and 51 (78%) were cryopreserved. Mean collected volume was 110 ml with 68% (75 ml) reduction and mean cryopreservation of 35 ml; ABO and Rh blood group systems were determined, HLA, class I, A and B loci, and class II, DR locus were typed by molecular biology methods using PCR-SSOP. Infectious disease screening was carried out for brucellosis, syphilis, Chagas, hepatitis B and C, HIV I and II, HTLV I and II, toxoplasmosis and cytomegalovirus. Two positive units for hepatitis B (anticore) and two positive units for Chagas were discarded. The quantity of total nucleated cells (TNC), CD34+ cells and the clonogenic capacity were determined twice at the collection and after the procedures of volume reduction previous to cryopreservation. A 5% reduction in both TNC and CD34 cells and a 10% in the colony forming units (CFU) were detected. A good correlation coefficient between TNC and CFU was obtained.

[Bone marrow transplantation in chronic myeloid leukemia]

Chronic Myelogenous Leukemia (CML) is an oncohematological disease characterized by a clonal proliferation concerning the primitive hematopoietic cell. A typical cytogenetic alteration known as Philadelphia Chromosome (Ph1), a 9:22 chromosomic translocation which produces a hybrid gene BCR/ABL, is present in 95% of the patients. Nineteen CML patients (9 female and 10 male) underwent Bone Marrow Transplantation (BMT). Median age was 32 years (range 9 to 47); 15 of them were in chronic phase (CP), and 4 in accelerated phase (AP). At diagnosis, all patients were Ph1+, BCR/ABL+. The conditioning regimen consisted of busulphan and cyclophosphamide while patients in AP received etoposide as well. Seventeen patients received cyclosporine A, methotrexate and methylprednisone as prophylaxis for Graft Versus Host Disease (GVHD) while 2 patients received only the first two drugs. The 9.22 translocation was determined by means of RT-PCT technique using the primers NB1+, Abl3, B2A, CA3 and A2. The sensitivity of the method was 1 x 10(-6). Among the 19 patients who entered the protocol, 14 are alive and in clinical, hematological and cytogenetic remission (Ph1-) and 3 patients died due to acute GVHD, 1 due to graft failure and 1 due to Hemolytic Uremic Syndrome. Of the 4 transplanted patients in AP, 3 are alive and in complete remission. The patients had a 74% survival, with a median follow-up of 655 days. Complete hematopoietic chimerism was demonstrated in 16 patients, with the study of 3 loci, D1S80, APO B and D17S30. No relationship was found between post BMT hybrid BCR/ABL (RT.PCR) persistence and disease relapse; the presence of acute and/or chronic GVHD did not influence the BCR/ABL positivity. In our experience, BMT has proved to be the only therapeutic alternative for CML with complete clinical, hematological and cytogenetic remission and a mean survival of 74%, comparable to the international experience.

HLA antigens and other genetic markers in the Mapuche Indians of Argentina

A total of 107 Mapuche Indians living in western Argentina were studied with respect to 16 genetic systems. For HLA, there were a few differences in relation to previous studies; and considering the averages observed in 15 other South American tribes, Mapuche Indians showed low values for A2, A9 and C3, but high ones for A28 and B16. This is the first report of the presence (in low frequencies, 1-6%) of alleles C2, C6 and C7, as well as of DR antigens (most frequent alleles DR4 and DR2) in South American Indians. Some peculiar reactions shown by products of locus B suggest the presence of antigens that are characteristic of the Mapuche. As for the other systems, the frequencies of R1 (Rh) and PGM1(1) were lower but those for r (Rh), GLO1 and Hp1 were higher than the averages obtained considering previous studies of this ethnic group. Other salient findings were the variability observed in the PGM2 and C3 systems, and the low prevalence of Bfs.

Idiopathic familial chondrocalcinosis due to apatite crystal deposition

Idiopathic familial chondrocalcinosis was found in five members of a family. The clinical features of the disease were morning stiffness, pain and limitation of motion of the dorsolumbar spine in four of the five members, associated with arthritis of the small joints of the hands in three, shoulder periarthritis in two and costal cartilage pain in one. Radiologically, four of the five patients had multiple intervertebral disk calcifications, mainly located at the nucleus pulposus area. Three of them also had periarticular calcific deposits, associated with costal cartilage calcifications and degenerative changes in the small joints of the hands in two. None of these cases showed cartilage calcification in the knees, public symphysis or triangular ligament of carpus. In the propositus, optical microscopy of a specimen of the second proximal interphalangeal joint obtained by open biopsy showed the presence of multiple calcified areas in the intercellular matrix and chondroid metaplasia with calcification of the matrix in the synovial membrane and capsule. X-ray diffraction studies, energy dispersive analysis, and infrared spectrophotometry of a costal cartilage sample obtained by open biopsy demonstrated the presence of carbonate calcium hydroxyapatite. In this study, no relation was found between HLA antigens, loci A, B and C, and this syndrome due to calcium hydroxyapatite crystal deposition.