Validation of a Polymerase Chain Reaction technique for Kidd blood group genotyping

The Kidd blood group antigens, Jkª and Jkᵇ , are two of the main surface markers which are found on the membrane of red blood cells. The determination of whether a donor or a recipient has the Jkª and/or the Jkᵇ antigens is crucially important to have a successful transfusion without the development of adverse incompatibility-related reactions. In Malta, routine serological-based tests are applied with the purpose of differentiating between homozygous and heterozygous states for the Jk antigens respectively. Although these tests are highly specific and sensitive, there are particular clinical scenarios where haemagglutination assays are not suitable for determining the individual’s Kidd blood group status. Additionally, the alternative genotyping procedure has never been applied in Malta within the context of blood grouping. The current study was therefore carried out to determine whether a molecular-based technique such as Polymerase Chain Reaction – Restriction Fragment Length Polymorphism analysis (PCR-RFLP) is a suitable alternative procedure for distinguishing amongst the three different Kidd phenotypes. After extracting deoxyribonucleic acid (DNA) from 50 blood samples obtained from serologically-tested healthy blood donors who expressed at least one of the Kidd antigens, PCR-RFLP analyses were carried out. The results of the latter were then compared with those previously obtained with haemagglutination and a complete match was observed between the two. Therefore, this PCR-RFLP method was confirmed as a suitable alternative laboratory technique that can be used to determine efficiently the Kidd blood group of both donors and recipients, in an accurate manner without subjectivity as encountered in the case of haemagglutination. This research further facilitates the introduction of molecular-based techniques in molecular blood transfusion.peer-reviewe

Cavity Mode Frequencies and Strong Optomechanical Coupling in Two-Membrane Cavity Optomechanics

We study the cavity mode frequencies of a Fabry-P\'erot cavity containing two vibrating dielectric membranes. We derive the equations for the mode resonances and provide approximate analytical solutions for them as a function of the membrane positions, which act as an excellent approximation when the relative and center-of-mass position of the two membranes are much smaller than the cavity length. With these analytical solutions, one finds that extremely large optomechanical coupling of the membrane relative motion can be achieved in the limit of highly reflective membranes when the two membranes are placed very close to a resonance of the inner cavity formed by them. We also study the cavity finesse of the system and verify that, under the conditions of large coupling, it is not appreciably affected by the presence of the two membranes. The achievable large values of the ratio between the optomechanical coupling and the cavity decay rate, $g/\kappa$, make this two-membrane system the simplest promising platform for implementing cavity optomechanics in the strong coupling regime.Comment: Contribution to the special issue on "Nano-optomechanics" in Journal of Optics, edited by I. Wilson-Rae, J. Sankey and H. Offerhau

The role of cell cycle regulation in cancer

During the past decades, cancer research has expanded rapidly due to the relatively high incidence rate of cancer and high death rate linked to it. The type and the extent of aggressiveness of particular cancers are determined by specific flaws in the cell cycle regulation. This study gives a detailed depiction of the cell cycle’s phases including the checkpoints being the G1 (GAP 1) phase, the G1/S (Synthesis) DNA damage checkpoint, the S phase, the G2 (GAP2) phase, the G2/M (Mitosis) DNA replication checkpoint, the M phase and the interphase. Regulation occurs at all the previous phases mainly through the formation of cyclins-CDKs (Cyclin Dependent Kinases) complexes. The latter control precisely the commencement and completion of the specific events leading to cell duplication and division by activating various genes such as the Rb (Retinoblastoma) gene. CDKs’ activity is in turn regulated by various factors such as phosphorylation, controlled degradation of cyclins, regulated synthesis of both CDKs and cyclins by growth factors and cytokines, as well as by CKIs (Cyclin-dependent kinase inhibitors) such as p15, p16, p18, p19, p21, p27 and p57. The balance between tumour suppressor genes such as p53 and Bax and antiapoptopic genes such as Bcl2 and IGF-BP3 has also been demonstrated with a particular focus on p53-"the guardian of the genome".peer-reviewe

Acute leukaemia

Acute leukaemia manifests itself into two different types being Acute Lymphocytic Leukaemia (ALL) and Acute Myelogenous Leukaemia (AML) depending on the type of leukocyte being affected. ALL raises a lot of concern since it is the most common type of leukaemia found in children while CML is the most common type of leukaemia in the United States. This study shows the epidemiology, the etiology, such as chromosomal aberrations and gene mutations and the clinical presentations consisting of both signs and symptoms. It also includes how these types of leukaemia are diagnosed as well as their pathophysiology which comprises detailed description of the alterations in various cellular mechanisms. Finally, the treatment involving both chemotherapy and stem cell therapy, amongst others, has also been discussed.peer-reviewe

Chronic leukaemia

Chronic leukaemia manifests itself into two different types being Chronic Lymphocytic Leukaemia (CLL) and Chronic Myelogenous Leukaemia (AML) depending on the type of leukocyte being affected. CLL is the most common type of leukaemia in adults in contrast to CML which is the rarest type of leukaemia. This study shows the epidemiology and the etiology, such as chromosomal aberrations and gene mutations which include upregulation of Bcl2, mutation of p53, 13q deletion, 11q22-23 deletion, 12q trisomy and 17p deletion for CLL and the fusion of the BCR and ABL genes in CML. It also includes the clinical presentations consisting of both signs and symptoms as well as how these types of leukaemia are diagnosed and their pathophysiology which comprises a detailed description of the alterations in various cellular mechanisms. The treatment involving both chemotherapy and stem cell therapy, amongst others, has also been discussed.peer-reviewe

Clinicopathological conference

In October 1969, professor V.G. Griffiths inaugurated monthly clinicopathological conferences at St. Luke's Hospital Malta. Two of the case studies presented at the April 1970 meeting are hereby published. A guest participant was professor Linell, of the University Institute for Pathology, associated with the Almanna Sjukhuset of Malmo, Sweden, who was then visiting the medical school. The main focus of the subject of the conference is on tumours of the kidneys and ureters, whereby an interesting discussion about the cases in question is presented, outlining the respective detailed medical examinations and evaluations processes.peer-reviewe

Effect of Axial Agitator Configuration (Up-Pumping, Down-Pumping, Reverse Rotation) on Flow Patterns Generated in Stirred Vessels

Single phase turbulent flow in a tank stirred with two different axial impellers - a pitched blade turbine (PBT) and a Mixel TT (MTT)- has been studied using Laser Doppler Velocimetry. The effect of the agitator configuration, i.e. up-pumping, down-pumping and reverse rotation, on the turbulent flow field, as well as power, circulation and pumping numbers has been investigated. An agitation index for each configuration was also determined. In the down-pumping mode, the impellers induced one circulation loop and the upper part of the tank was poorly mixed. When up-pumping, two circulation loops are formed, the second in the upper vessel. The PBT pumping upwards was observed to have a lower flow number and to consume more power than when down-pumping, however the agitation index and circulation efficiencies were notably higher. The MTT has been shown to circulate liquid more efficiently in the up-pumping configuration than in the other two modes. Only small effects of the MTT configuration on the power number, flow number and pumping effectiveness have been observed

Cooling atoms particles and polarisable objects using dissipative dipole forces

Optical cooling methods are generally applicable to a very restricted range of species. As a means of overcoming this problem, we explore the effect of the retarded interaction of any polarisable particle (an atom, a molecule or even a micromirror) with itself, similarly to cavity-mediated cooling. We use the transfermatrix method, extended to allow us to handle moving scatterers, to explore the most general configuration of a mobile particle interacting with any 1D combination of fixed optical elements. Remarkably, this model allows a solution in closed form for the force acting on the particle, without any a priori restriction on the nature of the particle

Design of micromixers using CFD modelling

The effect of various geometrical parameters of a grooved staggered herringbone micromixer on the mixing performance has been investigated using Computational Fluid Dynamics. Mixing quality has been quantified with spatial data statistics, maximum striation thickness and residence time analyses. The results show that the number of grooves per mixing cycle does not affect the mixing quality in an important way. On the other hand, a larger groove depth and width allow the maximum striation thickness to be rapidly reduced, without increasing the pressure drop across the mixer. Wide grooves, however, create significant dead zones in the microchannel, whereas deep grooves improve the spatial mixing quality

Gene structure of the human metabotropic glutamate receptor 5 and functional analysis of its multiple promoters in neuroblastoma and astroglioma cells

The metabotropic glutamate receptor 5 (mGluR5) has a discrete tissue expression mainly limited to neural cells. Expression of mGluR5 is developmentally regulated and undergoes dramatic changes in association with neuropathological disorders. We report the complete genomic structure of the mGluR5 gene, which is composed of 11 exons and encompasses ∼563 kbp. Three clusters of multiple transcription initiation sites located on three distinct exons (IA, IB, and II), which undergo alternative splicing, have been identified. The 5′-flanking regions of these exons were isolated and, using a luciferase reporter gene assay, shown to possess active promoter elements in SKN-MC neuroblastoma and U178-MG astroglioma cells. Promoter IA was characterized by a CpG island; promoter IB contained a TATA box, and promoter II possessed three active Oct-1-binding sites. Preferential luciferase activity was observed in SKN-MC concomitant with differential DNA binding activity to several responsive elements, including CREB, Oct-1, C/EBP, and Brn-2. Exposure to growth factors produced enhanced expression of promoters IB and II in astroglioma cells and activation of NF-κB. These results suggest that alternative 5′-splicing and usage of multiple promoters may contribute regulatory mechanisms for tissue- and context-specific expression of the mGluR5 gene