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Introduction: Metformin is the most widely administered anti-diabetic medication among type 2 diabetes mellitus (T2DM) patients. However, metformin induces vitamin B12 malabsorption which may incre...

Type 2 Diabetes Mellitus (T2DM) is a metabolic disorder, characterized by persistent elevation of blood glucose either due to insulin resistance or insulin insufficiency. Metformin is the recommended first choice of drug for the management of T2DM and is known to improve insulin sensitivity and prevents hyperglycemia by reducing chronic inflammation. T-helper type 1 (Th1) and type 17 (Th17) cells, are important pro-inflammatory CD4

Background. Vitamin D is a steroid hormone important for the normal functioning of the body. It is produced through skin exposure to sunlight and from the diet. Although Ghana is located in the tropics where sunlight is abundant, factors like culture, diet, skin pigmentation, variation in the ozone layer, and geographical area influence the optimization of vitamin D concentration. It is imperative to evaluate the interplay between sunshine exposure, proinflammatory cytokines, and mediators of vitamin D metabolism and their relationship to vitamin D status in three geographical sections among apparent healthy Ghanaians. Methods and Results. In a cross-sectional study, a total of five hundred (500) healthy blood donors from three geographical areas in Ghana were enrolled. Their age ranged from 17 to 55 years with a mean age of 27.97 ± 8.87 years. The overall prevalence rate of vitamin D deficiency was 43.6% (218/500), with 41.2% (91/221), 45.3% (63/139), and 45.7% (64/140) of vitamin D deficiency being recorded in participants from the Northern Sector (NS), Middle Belt (MB), and Southern Sector (SS), respectively. However, there were no significant differences in the proportions of vitamin D deficiency across various geographical sectors. The median 25-hydroxyvitamin D serum levels were compared among geographical areas (NS, MB, and SS) and there were no significant differences ( P = 0.275 ) after adjusting for confounding factors. 25-Hydroxyvitamin D correlated positively with corrected ionized calcium (rs = 0.622, P ≤ 0.001 ) and phosphorus (rs = 0.299, P ≤ 0.001 ) and negatively correlated with SBP (rs = −0.092, P = 0.039 ), vitamin D binding protein (VDBP) (rs = −0.421, P ≤ 0.001 ), intact parathyroid hormone (iPTH) (rs = −0.0568, rs ≤ 0.001), IFN-gamma (rs = −0.684, P ≤ 0.001 ), and TNF-alpha (rs = −0.600, P ≤ 0.001 ). After adjusting for possible confounders, not having knowledge about vitamin D foods, taking fewer vitamin D foods, and higher levels of IF-γ and IL-10 were associated with a higher risk of having vitamin D deficiency. Conclusion. The prevalence of 25-hydroxyvitamin D deficiency is high among the general adult population in Ghana despite the abundance of sunlight. Increasing knowledge on vitamin D diet coupled with a daily intake of vitamin D dietary supplements is likely to reduce the risk of developing 25-hydroxyvitamin D deficiency.

Background The association between prolong metformin usage and B12 deficiency has been documented. However, the prevalence estimates of metformin-induced vitamin B12 deficiency showed substantial disparity among studies due to varied study definitions of vitamin B12 deficiency. Metformin blocks the calcium dependent absorption of the vitamin B12-Intrinsic Factor complex at the terminal ileum. Lack of intrinsic factor due to the presence of auto-antibodies to parietal cells (IFA) could lead to vitamin B12 deficiency and subsequently cause peripheral neuropathy. We investigated the prevalence of vitamin B12 deficiency using more sensitive, combined markers of vitamin B12 status (4cB12) and the immuno-biochemical mediators of vitamin B12 deficiency. Methods In this observational study, 200 consecutive consenting metformin-treated T2DM patients, aged 35 and above, attending the diabetic clinic at KATH were recruited. Vitamin B12 deficiency was classified based on the Fedosov age-normalized wellness quotient. Anthropometric measurement was taken as well as blood samples for immunological and biochemical mediators. Peripheral neuropathy was assessed using the Michigan Neuropathy Screening Instrument (MNSI). Statistical analysis was performed using the R Language for Statistical Computing. Results Using the combined indicator (4cB12), the prevalence of metformin induced vitamin B12 deficiency was 40.5% whilst the prevalence of MNSI-Q and MNSI-PE diabetic neuropathy was 32.5% and 6.5% respectively. Participants with vitamin B12 deficiency had significantly higher levels of IFA, GPA, TNF-α, TC, LDL and albumin compared to those with normal vitamin B12 levels (p < 0.05). Correlation analysis revealed a statistically significant negative association between 4cB12 and the immunological markers [IFA (rs = -0.301, p12 was negatively associated with TC (rs = -0.203, p = 0.004) and LDL (rs = -0.222, p = 0.002) but positively correlated with HDL (rs = 0.196, p = 0.005). Conclusion Vitamin B12 deficiency and diabetic neuropathy are very high among metformin-treated T2DM patients and it is associated with increased GPA, IFA, TNF-α and cardiometabolic risk factors (higher LDL and TC and lower HDL). Upon verification of these findings in a prospective case-control study, it may be beneficial to include periodic measurement of Vitamin B12 using the more sensitive combined indicators (4cB 12) in the management of patients with T2DM treated with metformin in Ghana.

Objectives. Sub-Saharan Africa (SSA) is observing an accelerating prevalence rate of type 2 diabetes mellitus (T2DM) influenced by gene-environment interaction of modifiable and nonmodifiable factors. We conducted a systematic review and meta-analysis on the heritability and genetic risk of T2DM in SSA. Methods. We reviewed all published articles on T2DM in SSA between January 2000 and December 2019 and available in PubMed, Scopus, and Web of Science. Studies that reported on the genetics and/or heritability of T2DM or indicators of glycaemia were included. Data extracted included the study design, records of family history, pattern and characteristics of inheritance, genetic determinants, and effects estimates. Results. The pattern and characteristics of T2DM heritability in SSA are preference for maternal aggregation, higher among first degree compared to second-degree relatives; early age-onset (ABCC8, Haptoglobin, KCNJ11, ACDC, ENPP1, TNF-α, and TCF7L2 were found to be associated with T2DM, with overlapping effect on specific cardiometabolic traits. Genome-wide studies identified ancestry-specific signals (AGMO-rs73284431, VT11A-rs17746147, and ZRANB3) and TCF7L2-rs7903146 as the only transferable genetic risk variants to SSA population. TCF7L2-rs7903146 polymorphism was investigated in multiple studies with consistent effects and low-moderate statistical heterogeneity. Effect sizes were modestly strong [odds ratio=6.17 (95% CI: 2.03-18.81), codominant model; 2.27 (95% CI: 1.50-3.44), additive model; 1.75 (95% CI: 1.18-2.59), recessive model]. Current evidence on the heritability and genetic markers of T2DM in SSA populations is limited and largely insufficient to reliably inform the genetic architecture of T2DM across SSA regions.

Introduction and objectives: Several existing models have been developed to predict positive prostate biopsy among men undergoing evaluation for prostate cancer (PCa). However, most of these models have come from industrialized countries. We therefore, developed a prostate disease nomogram model to provide a basis for predicting a prostate biopsy outcome by correlating clinical indicators and diagnostic parameters among Ghanaian men. Subjects and methods: The study was a hospital-based cross-sectional prospective one which was undertaken at the Department of Surgery (Urology Unit) Komfo Anokye Teaching Hospital (KATH) from December, 2014 to March, 2016. In all a total of 241 patients suspected of having a prostate disorder due based on an abnormal digital rectal examination (DRE) findings and, or elevated prostate specific antigen (PSA) level underwent Trans-Rectal Ultrasonography (TRUS) guided biopsy of the prostate. Stepwise logistic regression was used to determine the independent predictors of a positive initial biopsy. Age, prostate-specific antigen (PSA), digital rectal examination (DRE) status, prostate specific antigen density (PSAD), history of alcohol consumption and history of smoking findings were included in the analysis. Two nomogram models were developed that were based on these independent predictors to estimate the probability of a positive initial prostate biopsy. Receiver-operating characteristic curves (ROC) were used to assess the accuracy of using the nomograms and PSA and PSAD levels for predicting positive a prostate biopsy outcome. Results: Prostate cancer was diagnosed in 63 out of 241 patients (26.1%). Benign prostatic hyperplasia was diagnosed in 172 (71.4%) of patients and the remaining 6 patients (2.48%) had chronic inflammation. Significantly elevated levels of PSA and PSAD were observed among patients with PCa compared to patients without PCa (p

Background: Lower urinary tract symptoms (LUTSs) can significantly reduce men's quality of life and may point to serious pathology of the urogenital tract. This study aimed at finding predictors of symptoms score on the International Prostate Symptom Score (IPSS) for patients with LUTS. Materials and Methods: The study was cross-sectional conducted among 225 Ghanaian men visiting the urology clinic at Komfo Anokye Teaching Hospital. Trained interviewers used the IPSS, which adds a quality of life question to the American Urology Association symptom index to determine the extent to which patients are troubled by their symptoms. Five milliliters of blood was collected for total prostate-specific antigen (PSA) measurement. Transrectal ultrasonography was performed to evaluate the prostate volume (PV). Results: The mean age of the participants was 67.96 ± 14.57. The average score obtained from the study participants using the IPSS scale was 17.52 ± 7.83. There was a significant association between bother score and IPSS symptoms grade (P < 0.0001). Regression plot of the participants' points for IPSS in relation to the age, PSA, and PV showed statistically significant positive associations (P < 0.05). However, the coefficients of determination (R2) were 0.156, 0.022, and 0.048, respectively. This means that each unit increase of age, PSA, and PV only influences 15.6%, 2.3%, and 4.8% of the change in the symptom score. There was statistically significant association between age and moderate-to-severe LUTS with age range of 75 years above recording the highest odds (adjusted odds ratio (AOR) = 18.72, (1.15–99.78), P < 0.0001). The PSA range 20.1–50 ng/ml was significantly associated with moderate-to-severe LUTS (AOR = 17.37 (2.19–223.45), P = 0.006). Moreover, other factors, which were significantly associated with moderate-to-severe LUTS, were smoking (AOR = 0.32 (0.11–0.94) P = 0.038) and being widowed (AOR = 0.05 (0.002–0.52), P =0.010) respectively. Conclusion: The study found a statistically significant correlation between age, PSA, PV, and IPSS scores; however, these influences were mild.

Objective The association between unbalanced iron indices and the conditions of schizophrenia are not well understood. Liver dysfunction which has been linked to iron metabolism might be a contributing factor. This case–control study evaluated serum iron indices and liver function in treatment-naïve schizophrenia patients and those already on treatment at the Psychiatric Department of the Komfo Anokye Teaching Hospital (KATH), Kumasi-Ghana. Results The mean age of the respondents was 39.6 ± 0.8 years. Increased levels of serum iron, TS, AST, ALT and AST:ALT ratio and lower levels of UIBC, TIBC, Transferrin, and log Ferritin:AST ratio levels were observed among the treatment-naïve group compared to the control. The treatment-naïve and treatment groups showed significantly higher serum AST:ALT ratio, and lower log10ferrtin:AST ratio than the healthy controls. There was a significant correlation between log10ferritin and AST, and log10ferritin and GGT in both treatments (r = 0.343; p = 0.003, and r = 0.502; p = 0.001 respectively) and treatment-naïve groups (r = 0.348; p = 0.002, and r = 0.614; p

Background Glycated hemoglobin (HbA1c), owing to its ability to reflect glycemia over a relatively longer time span, is still been investigated as an adjunct test for fasting plasma glucose (FPG) to identify subjects at risk of metabolic syndrome (MetS) in some Caucasian populations. However, whether or not HbA1c can serve as an adjunct to FPG in the definition of MetS in the Ghanaian population remains unknown. This study determined the prevalence of MetS and evaluated HbA1c ≥ 5.6% and FPG ≥ 5.6 mmol/l as the glycemic component of MetS among non-diabetic population in Ghana. Methods This was a case–control study conducted at St Francis Xavier Hospital, Assin Fosu, Central Region, Ghana. A total of 264 non-diabetic Ghanaian adults consisting of 158 newly diagnosed hypertensives and 106 normotensives, were recruited for the study. Fasting plasma insulin and glucose, HbA1c, and lipid profile was performed for each respondent. Results Using the FPG as glycemic criterion, the overall MetS prevalence was 46.6%, 37.1%, and 12.5% according by the IDF, NCEP ATP III, and WHO criteria, respectively. The prevalence of MetS using the HbA1c criterion was 54.2%, 52.7%, and 42.4% by the IDF, NCEP ATP III and WHO criteria, respectively. The HbA1c criterion identified more participants with MetS compared to the FPG criterion with a good agreement between HbA1c and FPG using the IDF and NCEP ATP III criteria (κ = 0.484 to 0.899) respectively. However, the overlap between HbA1c and FPG based diagnosis of MetS was limited for the WHO criterion. Conclusion The prevalence of metabolic syndrome is high among non-diabetics in Ghana. Introduction of HbA1c in addition to FPG in the screening of MetS improves identification of more people with MetS who would otherwise have been missed when only FPG-based diagnosis of MetS is used; with a substantial agreement with FPG, except when using the WHO criteria. Electronic supplementary material The online version of this article (10.1186/s13098-019-0423-0) contains supplementary material, which is available to authorized users.

Aims: To compare body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) as determinants of type 2 diabetes (T2DM) and determine optimal cut-offs in a sub-Saharan African population. Methods: Data from the RODAM study including Ghanaians aged 25–70 living in rural Ghana, urban Ghana and Europe were used. Logistic regression was used to assess associations between BMI, WC, WHR and T2DM status, by sex and site. Area under the curve (AUC) were constructed to discriminate between indices and establish performance and cut-off values. Results: WHR had the strongest association with T2DM in men and women across sites, except for rural men. The highest adjusted odds ratio (aOR) and AUC were in rural women for WHR (aOR = 2.09, 95%CI = 1.47–2.99; AUC = 0.71). Among migrants, WHR had higher AUCs compared with BMI (p < 0.01) and WC (p < 0.05). Cut-offs for BMI and WC in men were lower compared with the WHO reference across sites (WC: 85.4–93.7 vs 102 cm, BMI: 23.1–28.2 vs 30.0 kg/m 2). Conclusions: WHR outperformed BMI and WC as anthropometric indices in relation to T2DM among Ghanaian migrants. The lower BMI and WC cut-offs for T2DM than WHO established standards, highlights the need for African specific cut-offs to avoid missing high risk populations.

Background. Type 2 Diabetes Mellitus (T2DM) and menopause are associated with vitamin D status. Oestrogen decline during menopausal stages promotes hypovitaminosis D. However, the interplay between vitamin D, menopause, lifestyle, and T2DM cannot be overlooked. This study assessed vitamin D status among pre- and postmenopausal T2DM women and determined its association with glycemic control and influence of lifestyle habits on hypovitaminosis D.Methods. This cross-sectional study was conducted at the Komfo Anokye Teaching Hospital, Kumasi, Ghana. Structured questionnaires were administered to 192 T2DM women; blood samples were collected for estimation of 25(OH) D and insulin using ELISA. Fasting blood glucose (FBG), lipid profile, glycated haemoglobin (HbA1c), and calcium were measured. Statistical analyses were performed using Graphpad Prism 6.Results. The prevalence of vitamin D inadequacy was 92.2%. Hypovitaminosis D was more prevalent among the postmenopausal T2DM women (63.8% versus 58.2%). Hypovitaminosis D significantly associated with insulin [R2=0.01760,p=0.0008], HbA1c [R2=0.3709,p=<0.0001], and FBG [R2=0.3465,p=0.0001] in only the postmenopausal women.Conclusion. Vitamin D deficiency is prevalent in pre- and postmenopausal T2DM but higher among postmenopausal women. Adequate vitamin D levels in both groups were associated with improved glucose control while hypovitaminosis D in the postmenopausal women was related to poorer glucose control. Vitamin D screening should be incorporated into management plan for T2DM to serve as an early tool for prevention of vitamin D deficiency.

Department of Medicine, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana/Komfo Anokye Teaching Hospital, Kumasi, Ghana. Department of Molecular Medicine, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. 3 Emena Diagnostic Centre, Aninwah Medical Centre, Kumasi, Ghana. Department of Clinical Biochemistry, Diagnostic Directorate, Komfo Anokye Teaching Hospital, Kumasi, Ghana. Department of Medical Laboratory Science, School of Allied Health Sciences, University of Health and Allied Health Sciences, Ho, Ghana. 6 School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. 7 Kumasi Centre for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Ghana.

Background Vitamin D plays a major role in physiological processes that modulate mineral metabolism and immune function with probable link to several chronic and infectious conditions. Emerging data suggests a possible influence of vitamin D on glucose homeostasis. This study sought to provide preliminary information on vitamin D status among Ghanaian type 2 diabetics and assessed its association with glucose homeostasis. Methods In a case control study, 118 clinically diagnosed Type 2 Diabetes Mellitus (T2DM) patients attending Diabetic Clinic at the Nkawie Government Hospital were enrolled between October and December 2015. Hundred healthy non-diabetics living in Nkawie district were selected as controls. Structured questionnaires were administered to obtain socio-demographic data. Venous blood samples were taken from both cases and controls to estimate their FBG, Lipid profile spectrophotometrically and IPTH, 25OHD by ELISA. Statistical analyses were performed using SPSS v20.0 Statistics. Results The average age of the study participants was 58.81years for cases and 57.79year for controls. There was vitamin D deficiency of 92.4% among T2DM cases and 60.2% among the non diabetic controls. Vitamin D deficiency did not significantly associate with HOMA-β [T2DM: r2 = 0.0209, p = 0.1338 and Control: r2 = 0.0213, p = 0.2703] and HOMA-IR [T2DM: r2 = 0.0233, p = 0.1132 and Control: r2 = 0.0214, p = 0.2690] in both the controls and the cases. Conclusion Vitamin D deficiency is prevalent in both T2DM and non-diabetics. There is no association between vitamin D deficiency and insulin resistance or beta cell function in our study population. Vitamin D supplementation among type 2 diabetics is recommended.

The surge in prevalence of chronic noncommunicable diseases like hypertension and chronic kidney disease has been linked with modifiable lifestyle practices and increased body fat. This study sought to compare the association between different modifiable lifestyle practices, adiposity indices, renal function parameters, and hypertension as well as the predictive implications for levels of these parameters in target cardiac organ damage among an urban Ghanaian hypertensive population. Using a hospital-based case-control study design, 241 Ghanaian indigenes from the Kumasi metropolis were recruited for this study. The case group was made up of 180 hypertensives and 61 normotensives served as controls. In addition to sociodemographic data, standard haemodynamic, anthropometric, renal function, and cardiac organ damage assessments were done. The prevalence of chronic kidney disease (CKD) ranged from 13.3% to 16.6% depending on the equation used in estimating the glomerular filtration rate (eGFR). Percentage cluster distribution by chronic kidney disease was observed to be significantly tilted toward the upper quartiles (3rd and 4th) of the haemodynamic parameters measured. Chronic kidney disease was significantly higher among self-reported smokers and alcoholic hypertensives. In this urban population, adiposity was associated with hypertension and renal insufficiency. Chronic kidney disease was associated with hypertension and cardiac abnormalities.

Background: Laryngeal, tracheal and bronchial receptors are stimulated by mechanical and chemical irritants during laryngoscopy and endotracheal intubation. That almost always triggers powerful cardiovascular responses. Various attempts have been made to attenuate these responses. The aim of this study was to compare the efficacy and safety of cardiac antidysrhythmic drugs lidocaine, diltiazem and esmolol in the attenuation of cardiovascular responses to endotracheal intubation in the Black normotensive population. Patients and Methods: A randomized controlled trial was conducted in 160 adult patients of ASA physical status I or II undergoing various elective surgeries. The patients were randomly divided into four groups of 40 patients in each group - C, L, D, and E. Group - “C” received no drug (control) as placebo, group -“L” received 1.5 mg kg-1 preservative free lidocaine, group -“D” received 0.2 mg kg-1 diltiazem, and group-“E” received 2mg kg-1 esmolol IV. Group “C”, “D” and “E”, “L” one and two minutes before intubation. Changes in Heart Rate (HR), Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), and Mean Arterial Pressure (MAP) were measured and then compared within and between groups. Rate Pressure Product (RPP) was calculated and evaluated as well. Patients were also observed for any complications. Result: There was a significant increase in SBP, DBP, HR, MAP and RPP from the base line in control group “C” at 1 minute with onward decreases at 3 and 5 minutes respectively after intubation. Percentage change in haemodynamic variables in groups C, L, D and E at 1 minute are as follows: SBP=23.58%, 11.84%, 9.64% and 9.9%, DBP=18.73%, 18.89%, 11.93% and 10.40%, HR=30.45%, 26.00%, 7.01% and 1.50%, MAP=20.80%, 15.89%, 10.90 and 10.20%; RPP=61.44%, 40.86%, 17.26% and 11.68% respectively. Only patients receiving placebo had increased SBP, DBP, HR, MAP and RPP values after intubation compared with baseline values (p

Pregnancy-Induced Hypertension (PIH) is one of the leading causes of maternal, neonatal and infant mortality. Several studies have suggested that the occurrence of PIH may be dependent on environmental factors. Although, several countries have documented the prevalence of PIH, little is known about the occurrence and seasonal variations in the incidence of PIH in Ghana. This study was therefore conducted to assess whether seasonal variation has any effect on the prevalence of PIH. Between, 2006 and 2007, a retrospective observational hospital-based study was conducted at the Obstetric and Gynaecology Department of the Komfo Anokye Teaching Hospital (KATH) using pregnancies of gestational age more than 20 weeks. Maternal age, par-ity, birth weight and maternal death, occurrence of gestational hypertension, preeclampsia, PIH and seasons were variables evaluated and analyzed using SAS System for windows, version 6.12. Of the total of 8,091 antenatal visits to the Hospital, 12.42% presented with PIH, 6.55% with preeclampsia whilst gestational hypertension was identified in 5.87% of pregnant women. The younger mothers as well as the older aged mothers were more prone to presenting with these conditions and delivery of low birth weight babies was more prevalent among these cohorts of women. The prevalence for all the above-mentioned conditions generally declined during the dry season. An association between the rainy season and increased incidence of hypertensive disor-ders of pregnancy was evident. The hypertensive condition was more prevalent among the ex-tremes of age and associated with the delivery of babies with low birth weight.

Background: Direct laryngoscopy and endotracheal intubation always trigger powerful cardiovascular responses. Various attempts have been made to attenuate these responses. The aim of this study was to compare the efficacy and safety of esmolol and lidocaine for suppressing cardiovascular response to laryngoscopy and tracheal intubation in a normotensive African population. Materials and Methods: A randomized controlled trial was conducted in 120 adult patients of American Society of Anaesthesiologists (ASA) physical status I or II undergoing various elective surgeries. The patients were randomly divided into three groups of 40 patients in each group - C, L, and E. Group - C received no drug (control) as placebo, group -L received 1.5 mg kg -1 preservative free lidocaine and group -E received 2 mg kg -1 esmolol IV 2 min before intubation. Mean arterial pressure (MAP) and rate-pressure product (RPP) were measured before induction as baseline and after tracheal intubation at minute 1, 3, and 5. The patients were randomly allocated to receive either saline (Group C), lidocaine 1.5 mg/kg (Group L), or esmolol 2 mg/kg (Group E) ( n = 40, each group). After induction of general anesthesia with thiopental 6 mg/kg and vecuronium 0.12 mg/kg, the test solution was infused 2 min before tracheal intubation. Changes in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), and rate-pressure product (RPP) were measured before induction of general anesthesia (baseline), 1, 3, and 5 min after tracheal intubation. Patients were also observed for any complications. Results: There was a significant increase in HR, SBP, DBP, MAP, and RPP from the base line in control group C at 1 min with onward decreases at 3 and 5 min respectively after intubation. Percentage change in hemodynamic variables in groups C, L, and E at 1 min are as follows: HR = 30.45, 26.00, and 1.50%; MAP = 20.80, 15.89, and 10.20%; RPP = 61.44, 40.86, and 11.68%, respectively. Only patients receiving placebo had increased HR, MAP, and RPP values after intubation compared with baseline values ( P Conclusions: Prophylactic therapy with 2 mg kg -1 esmolol is more effective and safe for attenuating cardiovascular responses to laryngoscopy and tracheal intubation in a black population.