On Comparison of Some Imputation Techniques in Multivariate Data Analysis

Listwise or pairwise deletion as the method of handling missing data in multivariate data leads to loss of statistical power, biased results and underestimation of standard errors and P-values.Four imputation techniques namely Regression, Stochastic, Expectation-Maximization (EM) and Multiple Imputation (MI) were considered and compared in terms of preserving the original distribution of the (multivariate) data and the relationships among the variables before the techniques were applied. Results show that none of the techniques performed absolutely better than the rest leaving the choice of imputation techniques in any dataset on the objectives of the researcher. Keyword: Imputation, missing data, Expectation Maximization, Multiple Imputation, Root Mean Square Error

Unit Mean and Constant Variance of the Generalized Gamma Distribution after Square Root Transformation in Statistical modeling

In this paper, we studied the effect of square root transformation on the error component of the multiplicative error model whose distribution belongs to the generalized gamma family. The purpose of the study is to determine the effect of the said transformation on the basic assumptions; unit mean and constant variance required for statistical modeling. The special cases of the Generalized Gamma Distribution considered are the three-parameter Gamma distribution error component, the Chi-square, Exponential, Weibull, Rayleigh and Maxwell distributed error components. From the results of the study, the unit mean assumption is approximately maintained for all the distributions. It was also found that there were reduction in the variances of all the square root transformed distributions under study except those of the Gamma(a, b, 1), when a > 1, Rayleigh and Maxwell distributions that increased. Therefore we conclude that square root transformation is not appropriate for multiplicative error models with either a Gamma (a, b, 1), for a > 1 or Rayleigh or Maxwell distributed error component. Finally square root transformations where applicable are successful for the distributions under study if the variance of the transformed data < 0.5. Keywords: Generalized gamma distribution; Square root transformation; Mean; Variance; multiplicative error Model; Error componen

Spectrum of musculo-skeletal disorders in sickle cell disease in Lagos, Nigeria

<p>Abstract</p> <p>Background</p> <p>Sickle cell anemia (SCA) is a common genetic disease in Nigeria. Past studies from West Africa focused on isolated aspects of its medical and surgical presentations. To the best of our knowledge, the musculo-skeletal presentations amongst Nigerians with SCA have not been documented in a single all encompassing study. This work aims to prospectively document the musculo-skeletal disease burden among SCA patients.</p> <p>Methods</p> <p>In a prospective study of 318 consecutive patients with genotype-confirmed SCA at the Lagos University Teaching Hospital (LUTH), the musculo-skeletal pathologies, anatomic sites, grade of disease, age at presentation and management outcome were recorded over a one-year period. Data obtained were analyzed using Epi-Info software version 6.0. Data are presented as frequencies (%) and mean values (SD) as appropriate.</p> <p>Results</p> <p>The HbSS genotype occurred in 296 (93.0%), while 22 (7.0%) were HbSC. 100 (31.4%) patients with average presenting haemoglobin concentration of 8.2 g/100 ml in the study group, presented with 131 musculo-skeletal pathologies in 118 anatomic sites. Osteomyelitis 31 (31%) and septic arthritis 19 (19%) were most commonly observed in children less than 10 years. Skin ulcers and avascular necrosis (AVN) occurred predominantly in the older age groups, with frequencies of 13 (13.0%) and 26 (26.0%) respectively. 20 (71.5%) of diagnosed cases of AVN presented with radiological grade 4 disease. The lower limbs were involved in 84 (71.1%) of sites affected. Lesions involving the spine were rare 11 (0.9%). Multiple presentations occurred in 89 (28.0%) of patients; 62 (69.7%) of which were children below 10 years.</p> <p>Conclusions</p> <p>Musculo-skeletal complications are common features of sickle cell anaemia seen in 31.4%. Infectious aetiologies predominate with long bones and joints of lower limbs more commonly affected by osteomyelitis and septic arthritis. Healthcare providers managing SCA should be aware of the potential morbidity and mortality of these conditions to ensure early diagnosis and adequate management.</p

The Renoprotective Effect of Methanolic Extract of Portulaca Oleracea on Cisplatin-Induced Nephrotoxicity in Wistar Rats

This study was carried out to investigate the renoprotective effect of Portulaca oleracea on cisplatin-induced nephrotoxic wistar rats. Twenty four (24) female wistar rats were randomly divided into six (6) groups - Group A were given no treatment and served as the control group; Group B was given only a single dose of cisplatin (2ml/kg) and served as the cisplatin control group. Groups C and D were orally given 400mg/kg and 800mg/kg body weight of methanolic extract of portulaca oleracea (MEPO) respectively 6 hours after cisplatin injection (2ml/kg) . Groups E and F were orally given 400mg/kg and 800mg/kg body weight of MEPO respectively 6hours before cisplatin injection (2ml/kg) for 7 days. The effect of the treatment on relative kidney weight, serum creatinine level, serum uric acid and histoarchitecture of the rat kidney were accessed. Results showed significantly decreased serum creatinine levels (p&lt;0.05) in rats treated with 400mg/kg b.wt. and 800mg/kg b.wt.  MEPO as compared with the cisplatin control group. Serum uric acid was significantly decreased  in groups C, D, E, and F when compared with control A. The relative average weight of the kidney increased significantly in all treated groups except group treated with 800mg/kg b.wt. MEPO 6hours before cisplatin. Kidney histological slides showed both recovery from and prevention of effects of induced toxicity at all treatment doses. Results suggest that Portulaca oleracea extract may be used to cure or prevent cisplatin-induced renal toxicity without any adverse effect; hence it can serve as a novel combination agent with cisplatin to limit renal injury. Keywords: Cisplatin, portulaca oleracea, renoprotection, nephrotoxicity

Ground Vibrational State SiO Emission in the VLA BAaDE Survey

Using a subsample of the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey of stellar SiO masers, we explore the prevalence and characteristics of $^{28}$SiO $J=1-0, v=0$ emission. We identify 90 detections of maser, thermal, or composite $^{28}$SiO $J=1-0, v=0$ emission out of approximately 13,000 candidate spectra from the NSF's Karl G. Jansky Very Large Array (VLA). We find that the detected sources are likely asymptotic giant branch (AGB) stars belonging to a bright, foreground Milky Way stellar disk population. For the 32 sources showing thermal components, we extract values for outflow velocity by fitting thermal line profiles. We find a range of circumstellar envelope expansion velocities, and compare to previously recorded OH and CO expansion velocities. This preliminary survey is already the largest study of stellar ground-vibrational-state SiO masers to date, and will be expanded to include the entire VLA BAaDE dataset when data reduction for the 18,988 target sources is completed.Comment: 23 pages, 8 figures, to be published in The Astronomical Journa

Formulation and characterization of artemether-loaded sodium alginate microcapsules

Purpose: To increase the solubility of artemether (ART) in Transcutol® HP through microencapsulation in sodium alginate polymer to achieve&nbsp; sustained in vivo release.Method: Graded concentrations of ART (0.00, 0.25, 0.50, 0.75, and 1.00 g) microcapsules were produced using Tween® 80 by the cold&nbsp; homogenization method at 24 x 1000 rpm for 15 min. Characterization based on yield, encapsulation efficiency (EE), particle size, pH stability,&nbsp; differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and in vivo release using Peter’s four-day suppressive protocol in Wistar mice infected with Plasmodium berghei, were determined.Results: The results obtained indicate that 0.5 g ART-loaded microcapsules (AMC) showed the highest yield of 96.85 %. The EE of 88.3 %&nbsp; corresponded to 0.75 g ART-loaded microcapsules. DSC results revealed that there was a significant reduction in enthalpy in all the formulations compared to the crystalline drug, but no strong bond interaction occurred except for the blank microcapsules. The AMC1.0 showed high dose-dependent plasmodial growth inhibition of 88.75 % while AMC0.25 had the least (68.13 %).Conclusion: The artemether microcapsules showed sustained release characteristics for oral delivery of artemether and therefore may reduce some of the adverse effects associated with high dose artemether therapy in conventional oral tablets. Keywords: Malaria, Artemether, Transcutol® HP, Sustained-release, RBC count, Antiplasmodial activit

Qualities of Learning activities and Illustrations Provisions in the Recommended Chemistry Textbooks for Nigerian Secondary School Students

This study aimed at assessing the qualities of learning activities and illustrations in Nigerian Chemistry textbooks used at the penultimate grades. Five Chemistry textbooks were purposively selected from twenty-two approved and recommended Chemistry textbooks in which evaluation research design was used involving&nbsp;two research questions. The 5 selected Chemistry Textbooks were the instrument for data collection. Data collected were analyzed using QACEST proforma. Results of the study revealed a number of inadequacies in the learning activities and illustrations in these textbooks. It was also observed that none of the Chemistry textbooks emphasized&nbsp;learner centered approach of teaching and the constructivist approach writing

The Phytochemistry, Ethnobotanical, and Pharmacological Potentials of the Medicinal Plant-Vernonia amygdalina L. (bitter Leaf)

Background Vernonia amygdalina is traditionally used to treat a variety of diseases including diarrhoea, fungal and bacterial infections, inflammation, cancer, diabetes, and its squeezed juice can be applied on wounds. Objective This study reviewed the phytochemistry, ethnopharmacological, and pharmacological potentials of Vernonia amygdalina. Methods Literature search of relevant papers (1994-2021) were performed using ScienceDirect, Springer, Wiley and PubMed databases. For this review study, only publications written in English were utilized. Results The bioactive compounds extracted from Vernonia amygdalina includes 6β,10β,14β trimethylheptadecan-15 α-olyl-15-O-β-D-glucopyranosyl-1,5 β olide, glucuronolactone, 11 α-hydroxyurs-5,12-dien-28-oic acid-3 α,25-olide, 10-geranilanyl-O-β-D-xyloside, 1-heneicosenol O-β-D-glucopyranoside, apigenin, luteolin (3´,4´,5,7tetrahydroxyflavone), vernolide, hydroxyvernolide, 3′-deoxyvernodalol , vernodalol, diterpene (ingenol-3-angelate), vernomygdin, 4-methylumbelliferone, cephantharin, cryptolepine, isocryptolepine, neocryptolepine, courmarins, vernolepin, and vernoniosides. Various in vivo and in vitro studies revealed that V. amygdalina and its bioactive components possess pharmacological activities such as antioxidant, anti-inflammatory, anticancer, antimicrobial, hepatoprotective, antimicrobial, antidiarrheal, anti-diabetic, and neuroprotective activities. Conclusion This review demonstrated that V. amygdalina possess therapeutic effects against a wide variety of diseases. The efficacy of V. amygdalina in ameliorating diseases is attributed to its antioxidant activity and ability to improve the antioxidant system. Despite the vast pharmacological activities of V. amygdalina, more human clinical trials are needed to identify effective and safe doses for treatment of various diseases

Echocardiographic partition values and prevalence of left ventricular hypertrophy in hypertensive Nigerians

BACKGROUND: Left ventricular hypertrophy (LVH) is a well known independent risk factor for cardiovascular events. It has been shown that combination of left ventricular mass (LVM) and relative wall thickness (RWT) can be used to identify different forms of left ventricular (LV) geometry. Prospective studies have shown that LV geometric patterns have prognostic implications, with the worst prognosis associated with concentric hypertrophy. The methods for the normalization or indexation of LVM have also recently been shown to confer some prognostic value especially in obese population. We sought to determine the prevalence of echocardiographic lLVH using eight different and published cut-off or threshold values in hypertensive subjects seen in a developing country's tertiary centre. METHODS: Echocardiography was performed in four hundred and eighty consecutive hypertensive subjects attending the cardiology clinic of the University college Hospital Ibadan, Nigeria over a two-year period. RESULTS: Complete data was obtained in 457 (95.2%) of the 480 subjects (48.6% women). The prevalence of LVH ranged between 30.9–56.0%. The highest prevalence was when LVM was indexed to the power of 2.7 with a partition value of 49.2 g/ht(2.7 )in men and 46.7 g/ht(2.7 )in women. The lowest prevalence was observed when LVM was indexed to body surface area (BSA) and a partition value of 125 g/m(2 )was used for both sexes. Abnormal LV geometry was present in 61.1%–74.0% of our subjects and commoner in women. CONCLUSION: The prevalence of LVH hypertensive patients is strongly dependent on the cut-off value used to define it. Large-scale prospective study will be needed to determine the prognostic implications of the different LV geometry in native Africans