Because an adequate blood supply to and within tissues is an essential factor for successful tissue regeneration, promoting a functional microvasculature is a crucial factor for biomaterials. In this ...study, we demonstrate that short self-assembling peptides form scaffolds that provide an angiogenic environment promoting long-term cell survival and capillary-like network formation in three-dimensional cultures of human microvascular endothelial cells. Our data show that, in contrast to collagen type I, the peptide scaffold inhibits endothelial cell apoptosis in the absence of added angiogenic factors, accompanied by enhanced gene expression of the angiogenic factor VEGF. In addition, our results suggest that the process of capillary-like network formation and the size and spatial organization of cell networks may be controlled through manipulation of the scaffold properties, with a more rigid scaffold promoting extended structures with a larger inter-structure distance, as compared with more dense structures of smaller size observed in a more compliant scaffold. These findings indicate that self-assembling peptide scaffolds have potential for engineering vascularized tissues with control over angiogenic processes. Since these peptides can be modified in many ways, they may be uniquely valuable in regeneration of vascularized tissues.
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.
Includes bibliographical references (p. 20).
Prior research has shown that the control response of the ...limbs is affected by the mechanical properties of the limb and the feedback properties of the CNS. Cerebellar ataxia describes a situation in which damage to the cerebellum results in compromised motor control. It is characterized by such things as a clumsy or disturbed gait, a lack of balance and coordination, and unsteady speech patterns; for severe cases of ataxia, gross muscle coordination can degenerate to the point where successful, coordinated movements are not possible. In order to better understand the control deficit experienced by ataxic persons, estimates of the feedback properties of the CNS and the limb-muscle mechanical properties and will be necessary. Specifically, this investigation hopes to determine to what extent ataxia is cause by abnormal effective stiffness. Because ataxic patients do not exhibit deficits in strength or postural maintenance, we hypothesize a priori that the measured stiffness of ataxic subjects will be normal. We test this by conducting postural stiffness study on an ataxic subject, and measuring stiffness for two degrees of subject co-activation - minimal subject co-activation and maximal subject co-activation - and for different equilibrium postures.
(cont.) Because the observed kinematic trajectory following neuromuscular activation, as well as the ability of the limb to maintain a given posture in an external force field will be a result of the CNS reflex responses as well as the mechanical properties of the limb-muscle system, we expect all measurements of stiffness to be affected by CNS reflex responses. These reflex responses tend to be noticed between 20 msec (spinal reflexes) and 150 msec (long-loop reflexes) after an environmental disturbance, and because measurements of muscle stiffness require that we wait at least that long after external force application, we expect their contribution to the stiffness measurements to be represented. Our findings show the postural stiffness measured at six static positions in a 0.23 meter by 0.23 meter horizontal workspace and centered 0.45 m in front of the ataxic subject were within (something %) of those measured for a normal subject, and within the range reported by MussaIvaldi. As expected, however, the kinematics of cross-body hand movements were significantly different for the ataxic and normal subject. These results indicate an intact postural regulation for the ataxic subject but a deficit in dynamic control when compared to the normal subject.
by Olumuyiwa A. Oni.
S.B.
To better understand the subsurface geological composition (relief, fault, fracture, discontinuities, orientation of structures) of the surrounding environment that anticipates infrastructural ...development in the near future due to population explosion, an Electrical Resistivity Tomography (ERT) survey was conducted in Igarra, Akoko Edo area of Edo state, Nigeria. The depth to bedrock, possible geologic structures (faults, fractures, voids) were some of the properties investigated. To determine the orientation and continuity of the underlying geological features, 2D resistivity surveys were conducted along three parallel traverses (S-N orientation) with a total length of 205m and an inter-traverse spacing of 50m. The ERT results demonstrate that there are constant areas of low resistivity along the three traverses. Stations between 70 m – 90 m and 110 m – 150 m revealed low resistivity values, indicating possible geological structure. As seen in the resistivity pseudo-section, competent beds can be found at around 5 m and about 10 m in some stations (70 – 90 m and 110 – 150 m). It is generally accepted that geological features (fault, fracture) that pose a risk to geotechnical and engineering projects can be found in the regions with low resistivity. According to the research, pervasive underground geological structures are to blame for most road failures. Since electrical resistivity tomography is useful in describing an engineering site, further geophysical investigation for hydrogeological objectives should be undertaken on the identified faulted and fractured zones to establish its hydrologic importance and reserved for such.
Background: The global burden of hepatitis (inflammation of the liver) infection is still a major public health challenge and burden in the 21st century, especially in endemic regions due to ...unavailability of early diagnostic techniques and treatments. The presence of chronic or fulminant hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection(s) had caused extensive and irreversible liver damage in different population groups from different parts of the world today, including Nigeria. Aim: The aim of this study was to determine the seropositivity prevalence rates of HBV and HCV infections among pregnant women attending antenatal clinic at the State Specialist Hospital Akure, Ondo State, Nigeria. Materials and Methods: A review of hematological data was done for a period of 1 year which spanned from May 2015 to April 2016. During this period, pregnant women were recruited prospectively from the antenatal clinic and screened for HBV and HCV infections. The evaluation includes risk factor assessment based on age group and determination of rapid serology for hepatitis B surface antigen (HBsAg) and hepatitis C antibodies. Results: The results from our study revealed that out of the 1758 pregnant women recruited and screened, 1.47% and 0.00% within the age range of 25–29 years were positive to HBsAg and HCV, respectively. Conclusion: In conclusion, the 4.2% overall prevalence rate obtained for HBsAg-positive women fell within the reference range for the general population in Nigeria (2.4%–18.4%). The observed overall prevalence value for HBsAg positive women also fell within the 2%–7% reference range for South-Western region geographical prevalence category for Nigeria which showed an intermediate endemic rate within the age range of 25–39 years. The prevalence outcome of this study is an alert threshold attributed to endemic sexual activity of this age range (25–39 years) and prevailing epidemic factors for HBV transmission among reproductive age group.
Aim: The aim of this study was to determine the prevalence, pattern and determinants of menstrual abnormalities in HIV‐positive Nigerian women.
Methods: A cross‐sectional study was carried out ...involving 3473 (2549 HIV‐seropositive and 924 seronegative) consecutive and consenting women seen at the HIV treatment centers at the Nigerian Institute of Medical Research, Lagos and the Federal Medical Centre, Markurdi.
Results: The sociodemographic characteristics of the two groups were comparable, except for body mass index (BMI): the HIV‐negative women (28.1 ± 8.1) had statistically significantly (P < 0.005) higher BMI compared to the HIV‐positive women (21.9 ± 7.5).
Menstrual abnormalities were significantly more common in women living with HIV/AIDS (29.1%) compared to the HIV‐negative (18.9%) women (P < 0.001). The proportions of women in the two groups with intermenstrual bleeding, menorrhagia, hypermenorrhea, and postcoital bleeding were similar (P > 0.005), however amenorrhea, oligomenorrhea, irregular periods and secondary dysmenorrhea were more common in the HIV‐positive women (P < 0.02). Primary dysmenorrhea was less common in HIV‐positive women (P < 0.03). Among the HIV‐positive women, menstrual dysfunction was more common in women living with HIV/AIDS with opportunistic infections, CD4 count < 200, not undertaking therapy, symptomatic disease and BMI < 20. However, after controlling for cofounders, only CD4 < 200 (odds ratio OR, 3.65; 95% confidence interval CI, 1.2–9.7), BMI < 20 (OR, 2.4; 95%CI, 1.3–3.5) and not taking antiretroviral drugs (OR, 2.05; CI, 1.7–6.5) were associated with amenorrhea, oligomenorrhea, irregular periods and secondary dysmenorrhea.
Conclusion: HIV‐positive women in this study experienced more menstrual abnormalities of amenorrhea, oligomenorrhea, and irregular periods compared to the HIV‐negative controls. HIV‐positive women with CD4 count < 200, BMI < 20 and who do not take antiretroviral drugs are at the greatest risk.
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