A Proposed Nth – Order Jackknife Ridge Estimator for Linear Regression Designs

Several remediation measures have been developed to circumvent the problem of collinearity in General Linear Regression Designs. These include the Generalized Ridge, Jackknife Ridge, second- order Jackknife Ridge estimation procedures. In this paper, an nth-order Jackknife Ridge estimator is developed using canonical parameter transformation. Using the MATLAB version 7 software, parameter estimates, biases and variances of these estimators are computed to show their behavior and strengths. The results show that the parameter estimates are basically the same for all the methods. There is variance reduction at the Generalized Ridge estimator and at the ordered Jackknife Ridge estimators, though the Generalized Ridge estimator is slightly superior in this respect. As the order of Jackknife Ridge estimator increases, the variance decreases up to a certain nth-order and remains constant thereafter. Where variances of two consecutive estimators are the same or nearly so, the last but one estimator is considered optimal. This establishes a convergence criterion for the sequence of Jackknife Ridge estimators. It is shown from the five illustrative design matrices that higher order Jackknife Ridge estimators are superior to lower order Jackknife Ridge estimators in terms of bias. Thus further solving the problem of bias introduced by the Ridge estimator. Keywords: Canonical transformation; collinearity; mean square error; positive definite matrix; squared bias; variance inflation

Determination of Sphingosine-1-Phosphate in Human Plasma Using Liquid Chromatography Coupled with Q-Tof Mass Spectrometry

Evidence suggests that high-density lipoprotein (HDL) components distinct from cholesterol, such as sphingosine-1-phosphate (S1P), may account for the anti-atherothrombotic effects attributed to this lipoprotein. The current method for the determination of plasma levels of S1P as well as levels associated with HDL particles is still cumbersome an assay method to be worldwide practical. Recently, a simplified protocol based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the sensitive and specific quantification of plasma levels of S1P with good accuracy has been reported. This work utilized a triple quadrupole (QqQ)-based LC-MS/MS system. Here we adapt that method for the determination of plasma levels of S1P using a quadrupole time of flight (Q-Tof) based LC-MS system. Calibration curves were linear in the range of 0.05 to 2 µM. The lower limit of quantification (LOQ) was 0.05 µM. The concentration of S1P in human plasma was determined to be 1 ± 0.09 µM (n = 6). The average accuracy over the stated range of the method was found to be 100 ± 5.9% with precision at the LOQ better than 10% when predicting the calibration standards. The concentration of plasma S1P in the prepared samples was stable for 24 h at room temperature. We have demonstrated the quantification of plasma S1P using Q-Tof based LC-MS with very good sensitivity, accuracy, and precision that can used for future studies in this field

Sonographic Assessment of Tendo Calcaneus Thickness in a Nigerian Population

Aim: We aimed to determine tendo calcaneus thickness(TCT) and its relationships with body mass index (BMI), fasting blood sugar, and age and to determine gender impact on TCT in a Nigerian population. Materials and Methods: The present study adopted a cross‑sectional descriptive research design to assess the TCT of 264 adult  participants of a Nigerian population aged 30 years and above. A gray‑scale high‑resolution ultrasound machine, Sonoace 5500,  manufactured by Medicol in Korea, with a 10 MHz transducer was used to obtain the sonographic measurements of the tendo  calcaneus. The study was carried out at Assurance Medical Diagnostic and Research Center, Calabar. The weight and height of the participants were measured using an electronic weighing scale and meter rule, respectively. Only participants/volunteers whogave their informed consent for the study were included in the study. Ethical approval for the study was obtained from the Human Research and Ethical Committee of Assurance Medical Diagnostic and Research Center, Calabar, Cross River State. Statistical analysis was done using SPSS software version 16.0 (Statistical Package for the Social Sciences Inc., Chicago, IL, USA). Results: A strong positive correlation was obtained between TCT and gender (r = 0.72; P < 0.05); TCT also had a positive relationship with BMI (r = 0.421; P < 0.05). The male had significantly thicker tendo calcaneus (5.8 ± 1.4 mm) than their female (5.1 ± 1.6 mm) counterpart (P < 0.05). Conclusion: Results of the present study show that TCT is gender specific and may be useful in cardiovascular risk stratification due to its relationship with BMI, weight, and age, which are known risk factors of tendinopathy and cardiovascular disease. Keywords: Tendinopathy, tendo calcaneus, thickness, ultrasoun

Sonographic Evaluation of Maternal Splenic Dimensions in Normal Pregnancy

Aim: We aimed to establish sonographically the range of splenic dimensions in healthy pregnancy and to investigate their relationships with gestational age, maternal age body mass index (BMI), and parity of the mother. Materials and Methods: A prospective cross-sectional descriptive study of splenic dimensions was performed on 339 healthy, normal pregnant women aged 23–42 years. The spleen was measured with women in supine position on the couch. Scanning of the spleen was done with the women in deep inspiration so that the spleen descends. A Sonoline Omnia ultrasound imaging system with serial number 526,206,526 and model number Cc‐13 H71 fitted with a 3.5 MHz ultrasound probe was used in scanning the spleen along the lower left costal margin from the 9th to the 11th rib at the anterior, mid, and posterior axillary lines with the woman in the right lateral decubitus position using the oblique intercostal approach. Data were analyzed using SPSS software version 20.0 (SPSS Inc., Chicago, IL, USA). The relationship between splenic dimensions and gestational age, maternal age, and BMI was assessed using Pearson’s correlation coefficient. P ≤ 0.05 was considered statistically significant. Results: The result of the study shows that the mean length, width, thickness, and volume of the spleen of the mothers were 11.9 ± 0.7 cm, 5.7 ± 0.7, 9.5 ± 0.8 cm, and 381.6 ± 111.4 cm3, respectively. Gestational age was significantly correlated positively with splenic length and splenic volume of the mother (r = 0.37 and 0.31, P = 0.000). Conclusion: Splenic dimensions are higher in pregnant women compared to values reported for nonpregnant women and increases with gestational age and BMI of the mother

Awareness of Ear Health Care among Urban City Residents, in South‑South, Nigeria

Background: Exposure to Sound Pressure Levels (SPL) above 85 dB over 8 hours is potentially damaging to the ears. Unfortunately, many people may be unaware of the adverse effects of such SPL on the ear and quality of life. The level of awareness of hearing test has not been adequately determined in our region, a developing world. Some even seek ear care from unauthorized facilities and persons who often recommended inappropriate medications and treatment. The objectives of this study were to assess specifically the respondents’ level of awareness of sound levels that could cause hearing loss, determine the number of respondents who have had a hearing test, and the sources of ear healthcare among residents in an urban city in South-South, Nigeria. Participants and Methods: An interviewee‑administered questionnaire under three sections: socio‑demographics; awareness of  damaging sound levels and their sources; hearing testing and ear health care was used to collect data from 274 consenting respondents. Data were analyzed using IBM Statistical Product and Service Solution version 26.0. Results were presented on frequencies, percentages, tables, and figures. A P ≤ 0.05% was considered statistically significant at a 5% level of significance. Results: The respondents were aged between 10 and 74 years, and a median age of 24 years. Most 202 (73.7%) were males, while 72 (26.3%) were females, with male: female = 2.8:1. The greater proportion 223 (81.4%) were single; 177 (64.6%) were students; 16 (5.8%) were unemployed and 21 (7.7%) civil servants. Of the 274 consenting participants, only 79 (28.8%) were aware that the numerical value of noise level above 85 dB could cause damage to hearing. Only a small proportion with tertiary education 28 (10.2%) reported having had a hearing test. All the respondents in occupations prone to high levels of noise never had a hearing test. There was a statistically significant association between the types of ear drop/substance used by respondents and the attendant health personnel (P = 0.0001). Conclusion/Recommendation: There is poor awareness of ear health care among urban city dwellers in Calabar, South‑South, Nigeria. Most young adults aged 20–29 years were aware that loud noise is hazardous to hearing. Generally, there was ignorance on objective numerical noise levels for hazard; the importance of hearing testing; and utilization of appropriate ear care facilities for treatment of ear diseases. Public health education on appropriate ear healthcare is highly recommended. Keywords: Ear Health care Practices, Hearing Test, Sound level

Alternative definition of reliability measure according to the model allowing nonzero covariances of erros variables

If error components of items of any composite test are defined as antiimage variables from the set of these items, then maximizing reliability measure

The curious role of sarcomeric proteins in control of diverse processes in cardiac myocytes

Introduction Relatively recent developments in our understanding of sarcomeric proteins have expanded their role from the home of molecular motors generating force and shortening to a cellular organelle fully integrated in the control of structural, electrical, mechanical, chemical, and metabolic homeostasis. Even so, in some cases these diverse functions of sarcomeric proteins appear to remain a curiosity, not fully appreciated in the analysis of major controllers of cardiac function. This attitude toward the function of sarcomeric proteins in cardiac myocytes is summarized in the following definition of “curiosity,” which seems particularly apropos: “meddlesome; thrusting oneself into and taking an active part in others’ affairs.” We focus in this Perspective on how sarcomeric proteins function in integration with membrane channels and transporters in control of cardiac dynamics, especially in adrenergic control of cardiac function. Understanding these mechanisms at the level of cardiac sarcomeres took on special significance with the identification of mutations in sarcomeric proteins as the most common cause of familial hypertrophic and dilated cardiomyopathies. These mutations commonly lead to structural, electrical, and metabolic remodeling and to sudden death. These disorders indicate a critical role of processes at the level of the sarcomeres in homeostatic control of cardiac energetics, dynamics, and structure. Yet, control of Ca2+ delivery to and removal from the myofilaments has dominated discussions of mechanisms regulating cardiac contractility. We first provide an alternative perspective in which rate processes at the level of the sarcomeres appear to be dominant during the rise and maintenance of systolic elastance and of isovolumic relaxation. A discussion of established adrenergic mechanisms and newly understood anti-adrenergic mechanisms controlling sarcomere response to Ca2+ follows and expands on this perspective

Socio-demographic determinants of mammography uptake among women of 40 years and above in Calabar, South-South, Nigeria: a cross-sectional study

INTRODUCTION: mammography has the potential for identifying high risk women with breast cancer. Early detection is important in reducing mortality and morbidity, and crucial for better prognosis. Mammography is poorly practiced in Nigeria. This study assessed the association between socio-demographic characteristics and uptake of mammography among women ≥40 years. METHODS: a cross-sectional descriptive study design was employed and data was collected from 365 consenting participants in Calabar, Nigeria, using pre-tested questionnaire. SPSS Version 20 was used for data entry and analysis. The results were descriptively presented by frequencies and percentages. Pearson Chi-Square (χ2) analysis was performed to detect the association between variables at 5% level of significance (p-value of ≤0.05). RESULTS: only 9.9% of participants had a mammography, majority 90.1% never had. Uptake was highest among respondents with tertiary education, married, Civil/Public Servants, and those in the high income level categorization. Educational status, marital status, occupation and age were not statistically significantly associated with mammography uptake (p>0.05). Only religious denominational affiliation (p = 0.02) and income level (p = 0.002) were statistically significantly associated with uptake. Barriers to uptake were poor knowledge about mammography (49.8%), psychosocial (37.8%), economic (17.1%) and health systems (11.5%). Key facilitators to uptake were encouragement/counselling by health workers (44.0%) and presence of breast problems (37.4%). CONCLUSION: mammography uptake in Calabar, Nigeria was extremely low. Therefore, regular awareness campaigns targeting women at faith-based settings, and provision of mammography screening services at subsidized rates will enhance knowledge level and uptake of mammography

Thirty-five years (1986–2021) of HIV/AIDS in Nigeria: bibliometric and scoping analysis

Background Acquired immunodeficiency syndrome (AIDS) is an acquired defect of the cellular immunity associated with the infection by the human immunodeficiency virus (HIV). The disease has reached pandemic proportion and has been considered a public health concern. This study is aimed at analyzing the trend of HIV/AIDS research in Nigeria. Method We used the PUBMED database to a conduct bibliometric analysis of HIV/AIDS-related research in Nigeria from 1986 to 2021 employing “HIV”, “AIDS”, “acquired immunodeficiency syndrome”, “Human immunodeficiency virus”, and “Nigeria” as search description. The most common bibliometric indicators were applied for the selected publications. Result The number of scientific research articles retrieved for HIV/AIDS-related research in Nigeria was 2796. Original research was the predominant article type. Articles authored by 4 authors consisted majority of the papers. The University of Ibadan was found to be the most productive institution. Institutions in the United States dominated external production with the University of Maryland at the top. The most utilized journal was PLoS ONE. While Iliyasu Z. was the most productive principal author, Crowel TA. was the overall most productive author with the highest collaborative strength. The keyword analysis using overlay visualization showed a gradual shift from disease characteristics to diagnosis, treatment and prevention. Trend in HIV/AIDS research in Nigeria is increasing yet evolving. Four articles were retracted while two had an expression of concern. Conclusion The growth of scientific literature in HIV/AIDS-related research in Nigeria was found to be high and increasing. However, the hotspot analysis still shows more unexplored grey areas in future