The effects of radiation on tissue have generally been investigated in the context of therapeutic
irradiations, radiation protection and exposure to solar radiation. Typically attention has
concentrated primarily on cells, less consideration being given to the extracellular matrix (ECM).
ECM consists of collagen and elastin fibers immersed in a viscoelastic gel composed principally of
hyaluronan (HA) and proteoglycans. The present study examines changes in the physical properties of
the principle matrix micromolecules due to exposure to ionizing radiation. Freeze-dried rooster-comb
HA (Sigma) were used to give doses of 10-100 Gy for HA, to cover the range of irradiation exposure
during radiotherapy. The viscosity of HA (at 1.25% and 0.125% w/v) was measured by both cone and
plate and capillary viscometry, the former providing measurement at uniform shear rate and the latter
providing a more sensitive indication of changes. The Raman microspectrometry was employed to
characterize these changes on ECM molecular conformation. In regard to the viscometry, both
techniques (cone and plate and capillary viscometry) reveal a dose-dependent reduction in viscosity
(from 340 ± 194 cP for controls to 1500 ± 88 cP at a shear rate of 2 s-1 and dose of 75 Gy), again
suggesting depolymerisation.
The extracellular matrix (ECM) is a complex structural entity surrounding and supporting cells that
are found within mammalian tissue. This study presents the effect of ionizing radiation on the physical
properties of elastin which is usually found within arteries, lung, skin, ligantum nuchae, vocal chords
and elastic cartilage as a function of their composition and organization or architecture. X-ray from
an electron linac were used to give doses of 10-50Gy to cover the range of irradiation exposure during
radiotherapy. A uniaxial mechanical testing protocol was used to characterize the fibrous protein. For
pericardial the major change was an increase in the elastic modulus in the toe region of the curve (≤
20% strain), from 23±18 kPa for controls to 57±22 kPa at a dose of 10 Gy (p=0.01, α=0.05). At a
larger strain (≤ 20%), the elastic modulus in the region decreased from 1.92±0.70 MPa for control
pericardium tissue to 1.31±0.56 MPa (p=0.01, α=0.05) for 10 Gy X-irradiated sample. For elastin,
the stress-strain relationship was linear up to 30% strain, but the elastic modulus decreased
significantly with irradiation (controls 626±65 kPa, irradiated 474±121 kPa (p=0.02, α=0.05). The
results suggest that for elastin chain scissions are the primary effect of irradiation. The Raman
microspectrometry was employed to characterize these changes on ECM conformation.
Kappa-carrageenan is one form of necessary hydrocolloid. Hydrocolloids are macromolecular materials, which swell upon absorption of water; in some cases, forming a stiff gel in the presence of additives. This property is very important to suspend nanocarriers into gel network, which provide them long time stability at a varying temperature range. In this work, we prepared microemulsion and trapped these particles inside the kappa-carrageenan gel network. The microemulsion was composed of sodium N-lauroylsarcosinate hydrate (SNLS), oleic acid and deionized water. The purpose of this study was to immobilize them into the gel network, giving longer shelf life at a range of temperatures for oral drug delivery. Morphological properties were investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and Fourier transform infrared (FTIR) spectra. The TEM results showed that microemulsions are trapped in the gel network, and the diameter of the microemulsions are below 100 nm, which is comparable with the DLS results. The important functional groups of kappa-carrageenan and microemulsion were shown from the FTIR result of the complex microemulsion gel. These results confirmed the interaction between SNLS based microemulsion and kappa- carrageenan gel.
Dengue virus is one of the emerging agents that can be transmitted via blood transfusion from infected blood donors to recipients. In Malaysia, the increase in dengue infection may contribute to the existence of asymptomatic blood donors and increase the risk of blood supply contaminated with this virus. The aims of this study were to investigate the prevalence of NS1 dengue antigen among blood donors and to ascertain the demographic data of blood donors in Penang and and Perak. Methods: A total of 374 voluntary blood donors were recruited from two blood donation campaigns organised by Hospital Pulau Pinang, Penang and Hospital Raja Permaisuri Bainun, Ipoh, Perak from April to May 2016. From each centre, 187 voluntary blood donors were enrolled, blood was collected and Dengue NS1 Ag was screened on all the samples using Platelia dengue antigen test kit from Bio-Rad Laboratories, France. Results: All 374 samples were found to be negative for the Dengue NS1 antigen. Demographic data of these blood donors showed that the most common blood group was O Rh positive, men donated more than women and Chinese blood donors were the biggest group of donors. Conclusion: Even though dengue is endemic in Malaysia, none of the blood donors was screened positive for dengue NS1 antigen in the areas studied. This indicates that none of the blood donor at the time of donation was in viraemia stage. The established donor screening program ensures that the dengue transmission through transfusion is minimal in the areas studied.
Unilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) were prepared by the reverse-phase
evaporation method and extrusion through a polycarbonate membrane filter. Liposomes at 0.7 mg/mL lipid concentration
in deionized water were exposed to gamma irradiation at a dose in the range 0.5 to 25 kGy. Gamma irradiation of
liposomes resulted in the degradation of DPPC lipids into free fatty acids, lysophosphatidylcholine and 1,2-palmitoylphosphatidic
acid (DPPA). The effect of gamma irradiation towards the physical stability of liposomes was investigated
by means of dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential analysis. From
the DLS analysis, no significant changes were observed in the hydrodynamic size of liposomes. TEM images indicate that
the liposomes surface became smoother and rounder as higher irradiation doses were applied. Zeta potential analysis
showed that gamma irradiation of DPPC liposomes at radiation doses as low as 0.5 kGy resulted in a drastic rise in the
magnitude of the zeta potential. The results also demonstrate that gamma irradiation of liposomes suspension enhanced
the overall stability of liposomes. Hence, it can be concluded that gamma irradiation on DPPC liposomes may potentially
produce liposomes with higher stability.
Electricity has become one of the necessities for human daily activities. The presence of electric
current produces electromagnetic fields (EMF) at extremely low frequency (ELF). The problem arises
when scientists suggests a possible connection between ELF exposure to human health and safety.
Concerned about the safety and health of students and staff, Universiti Kebangsaan Malaysia (UKM)
took the initiative to identify possible ELF sources and measure their exposure in various locations
around the UKM main campus in Bangi. This paper reports the results obtained from the monitoring
of the magnetic flux density at three identified locations in the vicinity of the overhead high-voltage
transmission line which transverses the university compound and compare the maximum value results
with the exposure limit suggested by the International Committee on Non Ionising Radiation
Protection (ICNIRP) for ELF. Measurements were done with an (Extech) Three Axis
Electromagnetic Field (EMF) Meter (Model 430826) to determine the magnetic flux density. The
lateral profile method was applied as the standard measurement methodology. Results showed that the
maximum value of the magnetic flux density was 12.5 mG, which is below the suggested ICNIRP
public exposure limit of 1000 mG, or in percentage ratio, 1.25% of ICNIRP public exposure limit.
Results from the statistical Kruskal-Wallis test showed that there is a significant difference in the
distributions of the magnetic flux densities at the different locations (P < 0.05). In conclusion, the
measured locations are still safe for people in short-term exposure. However, long-term exposure
measurements still need to be done to provide concrete data on the ELF-emission levels in UKM.