Factors determining gender ratio in the Maltese population

Introduction: The Male/Female ratio at birth has been described to favour the male conceptus, a situation that persists throughout most of childhood and into the reproductive phase of life. The reasons behind this preferential male-favouring remain elusive. Methodology: The various relevant obstetric and population national registers kept by the Department of Health information and the National Statistics Office of the Maltese Islands were reviewed to elucidate the age-related M/F ratios differences in the population starting with the third trimester of the antenatal period. In addition, third trimester M/F ratios in women with specific metabolic-related disorders were assessed and compared to the on-affected individuals. The role of foetal congenital malformations was also investigated. Results: It would appear that the M/F ratio starts favouring the male conceptus as early as the third trimester of the antenatal period. It remains favoured right through the reproductive age reaching par after the age of 45 years when it shifts to favour the female. This relationship was significantly altered during the 1930s as a result of the emigration patters prevalent during that period. The results further show that the maternal nutritional and biochemical milieu may influence the M/F ratio at the beginning of the third trimester with women suffering from adiposity, diabetes and thyroid disease having higher M/R ratios. In spite of this preference to the male conceptus, malts have a higher mortality throughout life with mortality rates being higher for males from the third trimester up to the age of 75 years. On the other hand, female foetuses with malformations appear to have a higher mortality during intrauterine life than corresponding male foetuses. Conclusion: The M/F ratio appears to favour the male conceptus during antenatal life and is definitely evident by the beginning of the third trimester of pregnancy, the selection mechanism possibly being a greater predisposition of female foetal loss in the presence of malformations. These biological observations may present advantages within the breath of human reproductive ecology, ensuring a healthy reproductive female individual who has the option of choosing her mate from a competing male community.peer-reviewe

Structure analysis of biologically important prokaryotic glycopolymers

Of the many post-translational modifications organisms can undertake, glycosylation is the most prevalent and the most diverse. The research in this thesis focuses on the structural characterisation of glycosylation in two classes of glycopolymer (lipopolysaccharide (LPS) and glycoprotein) in two domains of life (bacteria and archaea). The common theme linking these subprojects is the development and application of high sensitivity analytical techniques, primarily mass spectrometry (MS), for studying prokaryotic glycosylation. Many prokaryotes produce glycan arrangements with extraordinary variety in composition and structure. A further challenge is posed by additional functionalities such as lipids whose characterisation is not always straightforward. Glycosylation in prokaryotes has a variety of different biological functions, including their important roles in the mediation of interactions between pathogens and hosts. Thus enhanced knowledge of bacterial glycosylation may be of therapeutic value, whilst a better understanding of archaeal protein glycosylation will provide further targets for industrial applications, as well as insight into this post- translational modification across evolution and protein processing under extreme conditions. The first sub-project focused on the S-layer glycoprotein of the halophilic archeaon Haloferax volcanii, which has been reported to be modified by both glycans and lipids. Glycoproteomic and associated MS technologies were employed to characterise the N- and O-linked glycosylation and to explore putative lipid modifications. Approximately 90% of the S-layer was mapped and N-glycans were identified at all the mapped consensus sites, decorated with a pentasaccharide consisting of two hexoses, two hexuronic acids and a methylated hexuronic acid. The O-glycans are homogeneously identified as a disaccharide consisting of galactose and glucose. Unexpectedly it was found that membrane-derived lipids were present in the S- layer samples despite extensive purification, calling into question the predicted presence of covalently linked lipid. The H. volcanii N-glycosylation is mediated by the products of the agl gene cluster and the functional characterisation of members of the agl gene cluster was investigated by MS analysis of agl-mutant strains of the S-layer. Burkholderia pseudomallei is the causative agent of melioidosis, a serious and often fatal disease in humans which is endemic in South-East Asia and other equatorial regions. Its LPS is vital for serum resistance and the O-antigen repeat structures are of interest as vaccine targets. B. pseudomallei is reported to produce several polysaccharides, amongst which the already characterised ‘typical’ O-antigen of K96243 represents 97% of the strains. The serologically distinct ‘atypical’ strain 576 produces a different LPS, whose characterisation is the subject of this research project. MS strategies coupled with various hydrolytic and chemical derivatisation methodologies were employed to define the composition and potential sequences of the O-antigen repeat unit. These MS strategies were complemented by a novel NMR technique involving embedding of the LPS into micelles. Taken together the MS and NMR data have revealed a highly unusual O-antigen structure for atypical LPS which is remarkably different from the typical O-antigen. The development of structural analysis tools in MS and NMR applicable to the illustrated types of glycosylation in these prokaryotes will give a more consistent approach to sugar characterisation and their modifications thus providing more informative results for pathogenicity and immunological studies as well as pathway comparisons.Open Acces

Sex differences in science achievement at G.C.E. 'O' level

It is usually taken for granted that boys are better than girls in science subjects. A recent study that shows science achievement of males and females separately indicates that this assumption has an empirical basis. Thus the I.E.A. (International Association for the Evaluation of Educational Achievement) study of science education in nineteen countries shows that boys consistently achieve significantly higher than girls in the physical science items at each of the three age levels sampled in every country, and the differences widen with increasing age.peer-reviewe

A new method for the representation and evolution of three dimensional discontinuity surfaces in XFEM/GFEM

The ability of the extended and generalized finite element methods of modeling discontinuities independent of mesh alignment requires a suitable representation for the discontinuity surfaces. In the present paper a method for constructing level set functions based on vector data and geometric operations in three dimensions is presented. In contrast to classical level set methods, the proposed approach does not require the integration of differential evolution equations, resulting in a particularly simple structure and easy implementatio

Hospitaller activities in medieval Malta

The Medieval Period in the Mediterranean World is generaly considered to cover a period of about a thousand years, and is considered to initiate with the end of the Roman era heralded by the division of the Roman Empure into two parts between the sons of Theodosius in AD 395. It ended with the advent of the Renaissance movement of the fifteenth century. This period in Malta was to see the Islands come under the influence of the Byzantine Empire encompassing the period prior to the ninth century; the Arab dominance starting in AD 870 and lasting until their formal expulsion in the mid-13th century; and the Latin phase of the late 13th century to the early 16th century when the islands were ceded to the Order of St. John of Jerusalem. The documentary sources dated to before the 14th century are rather scanty and often limited to ecclesiastical and political matters. A number of extant documents relate to medical matters, particularly with the setting up and management of hospital services and with matters relating to the affairs of hospitaller orders having links to the Maltese Islands.peer-reviewe

King George V Hospital in Malta : Sacra Infermeria for the Order of St. Lazarus of Jerusalem

King George V Hospital, originally commissioned in 1922, saw its closure in 1967. It was eventually reopened under the management of the Department of Health as Boffa Hospital in 1970. In the interim years, the budding Maltese jurisdiction of the Military and Hospitaller Order of Saint Lazarus of Jerusalem made serious bids to assume the management of the hospital hoping to set up a service for public and private-paying patients.peer-reviewe

A maternity unit in Gozo a hundred years ago

The present paper reviews the hospital confinements which occurred at Victoria Hospital in Gozo during the period 1876-1893. These hospital confinements are shown to have been generally restricted to needy women from the lower socio-economic strata. The lower socio-economic status of these mothers, together with the fact that these mothers were more likely to have significant medical and/or obstetric problems, resulted in higher perinatal and maternal mortality rates than those reported for the general population in Gozo and Malta. These observations are in conformity with the maternity care situation in European establishments.peer-reviewe

Application of moderate deviation techniques to prove Sinai's Theorem on RWRE

We apply the techniques developed in Comets and Popov (2003) to present a new proof to Sinai's theorem (Sinai, 1982) on one-dimensional random walk in random environment (RWRE), working in a scale-free way to avoid rescaling arguments and splitting the proof in two independent parts: a quenched one, related to the measure $P_\omega$ conditioned on a fixed, typical realization $\omega$ of the environment, and an annealed one, related to the product measure $\mathbb{P}$ of the environment $\omega$. The quenched part still holds even if we use another measure (possibly dependent) for the environment.Comment: 17 pages, 3 figures, 5 annexe