Black Kenyans Research Articles

Features of atherosclerosis in the tunica adventitia of coronary and carotid arteries in a black kenyan population.

Introduction. Histologic changes which occur in the tunica adventitia during initiation, progression, and complications of atherosclerosis are seldom reported. This study aimed at describing the features of atherosclerosis in the tunica adventitia of two of the commonly afflicted arteries, namely, left anterior descending coronary and common carotid in black Kenyans. Materials and Methods. Specimens from 108 individuals [76 males and 32 females, mean age 34.6] were processed for paraffin embedding. Seven micron thick sections were stained with Mason's trichrome and Haematoxylin/Eosin and examined with a light microscope. Results. Features of atherosclerosis were present in the tunica adventitia of 14.8% of left anterior descending arteries and 11.1% of common carotid arteries. Increase in adventitial thickness was associated with increased density of vasa vasora in 8.3% of both arteries. In the left anterior descending and common carotid arteries, 6.5% and 3.7% of cases, respectively, the tunica adventitia thickened without intimal hyperplasia. Conclusion. Features of atherosclerosis occur in the tunica adventitia of coronary and carotid arteries in over 10% of the black Kenyans studied. These features often precede the intimo medial changes. Tunica adventitia should therefore be prioritized in evaluation for atherosclerosis, in individuals at risk. This may enhance early detection and intervention.

Pattern of Origin of Anterior Inferior Cerebellar Artery in a Black Kenyan Population

Background: Pattern of origin of anterior inferior artery is important in interpretation of posterior circulatory stroke and during posterior cranial fossa surgery for aneurysms, arteriovenous malformations, tumors, posterior cerebral revascularization, and in diagnostic as well as interventional neuroradiology. The pattern displays ethnic variation but data from African populations are scanty. This study therefore aimed to describe the pattern of origin of anterior cerebellar artery in a black Kenyan population. Materials and Methods: One hundred and seventy three [99 male: 74 female] basilar arteries from adult formalin fixed brains were studied at Department of Human Anatomy, University of Nairobi, Kenya. Site and pattern of origin of anterior inferior cerebellar arteries were recorded. Data were analyzed by SPSS version 17.0 for Windows, and presented in a table and macrographs. Results: Anterior inferior cerebellar artery arose directly from basilar artery in 138 (79.8%), as common trunk with labyrinthine artery in 24 (13.9%), from verterbral and labyrinthine arteries in 3% cases each. Conclusion: In about 14% cases, anterior inferior cerebellar and labyrinthine arteries arise as common trunks from basilar artery. These proportions differ with those in prevailing literature from Caucasian and oriental populations. Extra care should therefore be exercised during surgery and neuroradiology in the posterior cranial fossa, and in interpretation of signs of posterior circulation stroke. Pre-operative ultrasound evaluation of the vascular bed is recommended.

Conventional and variant termination of the portal vein in a black Kenyan population

Knowledge of the variant terminations of the portal vein is important in surgical and interventional radiological procedures of the liver. Their pattern and frequency are important in planning surgery to minimize complications. They differ between populations, but data from Africa is unavailable. To investigate the variant termination of the main portal vein. One hundred livers from adult black Kenyans (age range 35 - 79 years) were studied at the Department of Human Anatomy, University of Nairobi, Kenya, by gross dissection. The livers were cleared of blood, fixed with 10% formaldehyde solution and the venous system infused with Acrylate monomers to keep the veins firm. The level of termination relative to the capsule and the branching pattern of the portal vein were examined. Various patterns were photographed using a digital camera. Data was analyzed using SPSS version 16.0 for windows and presented in tables and macrographs. Main portal vein termination was extracapsular in 14%, capsular in 40% and intrahepatic in 46%. Variant termination occurred in 49% of cases while conventional bifurcation occurred in 51% cases. Types, 2, 3 and 4 pattern of termination of main portal vein occurred in 15%, 22% and 12% cases respectively. The level of termination of the MPV had a positive correlation with its pattern (p=0.05). The high prevalence of variant termination of MPV in the current study suggests that the population is more vulnerable to inadvertent injury during surgery and radiological intervention. Besides, an extra hepatic termination of the MPV is more likely to have a conventional branching pattern compared to an intra-hepatic termination.

Regional Differences in the Diameter of Coronary Sinus among Black Kenyans

Background: Dimensions of the coronary sinus are important in the design of cannulation devices used in cardiac resynchronization therapy and percutaneous mitral valve annuloplasty. Gender and population variations may account for the failure rate of these procedures. Cardiac conditions requiring these procedures are common in black African populations. There are, however, hardly any studies on the regions of coronary sinus in these populations. Objective: To describe the regional diameters of coronary sinus among black Kenyans. Study design: Descriptive cross-sectional study. Materials and Methods: Coronary sinuses of 74 cadaveric hearts from black adult Kenyans (43 males and 31 females) were examined at Department of Human Anatomy, University of Nairobi, Kenya. Samples were classified into male and female and weighed. The coronary sinus was identified and cleaned to expose its entire extent. The length was divided into 3 segments; proximal, middle and distal. The circumference at the middle of each segment was obtained by measuring using a nylon string. This was divided by pie (3.14) to obtain the regional diameters. Data was analyzed using SPSS version 17. Sex comparison was established using student’s t test and Pearson’s correlation test was used to determine association between the diameters and heart weight. These were considered significant at a p-value of ≤0.05. Data were presented using scatter plots and tables. Results: The diameters at proximal, middle and distal segments were 8.67 ± 0.52 mm, 6.93 ± 0.77 mm and 5.83 ± 0.80 mm respectively. These correlated positively with weight of the heart. Females had significantly larger diameters. Conclusion: Diameters of coronary sinus show regional differences. They decrease distally, are larger in females and show positive correlation with weight of the heart. These features should be considered during design of and insertion of cardiac devices through the coronary sinus

Luminal Dimensions of Left Anterior Descending Coronary Artery in a Black Kenyan Population

Luminal diameter and percent stenosis of left anterior descending coronary artery are considered indicators of early atherosclerosis, arterial occlusion, myocardial infarction, and are important in quantitative estimation of coronary disease severity. These parameters show ethnic variation but there are hardly any data from African populations. This study examined luminal diameter and percent stenosis of 108 proximal left anterior descending coronary arteries. The specimens were obtained from adult individuals [72 males, 36 females; mean age 34.8 years (range 18 – 72 years] who had died of non-cardiovascular causes. The specimens were processed for routine paraffin embedding and sectioning. Seven-micron thick sections were stained with Mason’s trichome and examined with light microscope. Luminal diameter and percent stenosis were determined on the microscopic sections using multiscan software. The dimensions were corrected for heart weight and analyzed for age and gender differences. The mean luminal diameter was 2.72 ± 0.018 mm, with insignificant age and gender difference after correcting from heart weight. It increased with number of branches of left coronary artery. Mean percent stenosis was 34.6%. Percent stenosis of over 50% was present in 25% of individuals, all males. Of these, 8% were under 20 years. There was visible and focal intimal thickening. The mean luminal diameter is comparable to those reported from Caucasian and Asian populations, and there is significant percent stenosis in a substantial number of individuals. These findings suggest comparable vulnerability to atherosclerotic occlusion of left anterior descending.

Abdominal obesity has the highest impact on metabolic profile in an overweight African population

Aim: The aim of this study was to determine the association between different anthropometric parameters and metabolic profile in an overweight, adult, black Kenyan population.Methods: An opportunity sample of 245 overweight adult Kenyans (body mass index (BMI) ≥ 25 kg/m2) was analysed. A score of metabolic profile (metabolic Z-score) was constructed on the basis of levels of plasma lipids, blood pressure, blood glucose and serum insulin. Linear regressions using metabolic Z-score as outcome and six anthropometric variables (waist circumference (WC), hip circumference, visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue, arm fat area and arm muscle area) separately as independent variables were carried out.Results: Mean age of study participants was 42.1 years (SD = 9.6) and 26.5% of the participants were men. The median BMI was 28.6 kg/m2 (Q1 = 26.3; Q3 = 31.3). Of the six anthropometric variables tested, WC and VAT thickness had the strongest negative association with the metabolic profile (β = 0.17 (0.09; 0.24) and 0.15 (0.08; 0.23), respectively).Conclusions: WC and VAT thickness were the strongest anthropometric predictors for the metabolic profile in overweight adult Kenyans. WC is useful in clinical practice for the diagnosis of metabolically unhealthy fat accumulation in an African setting.

Pattern of Hypertensive Kidney Disease in a Black Kenyan Population

Background: Hypertensive kidney disease is a major cause of morbidity and mortality. Its pattern displays geographical and ethnic variations. Data on these patterns are important for informing management and prevention strategies, but on Kenyans such data are scarce. Objective: By means of a retrospective study at Kenyatta National Hospital, Nairobi, we aimed to describe the pattern of hypertensive kidney disease in a black Kenyan population. Methods: Records of hypertensive patients who had impaired kidney function between January 2000 and December 2010 were examined for mode of diagnosis, age, gender, comorbid factors, treatment and outcome. Data were analyzed using the Statistical Package for Social Sciences, version 16.0 for Windows, and are presented using tables and bar charts. Results: A total of 114 cases (72 males, 42 females) were analyzed. The mean age was 42.7 years (range 12–83), peaking at 51–70 years. The male to female ratio was 1.7:1. Comorbid factors included left ventricular hypertrophy (21.1%), congestive heart failure (15.8%), alcohol (11.4%), cerebrovascular accidents, smoking and retinopathy (10.5% each). Multiple comorbid factors were present in 8.8% of the cases. The majority (52.6%) of the patients survived on hemodialysis, 8.8% underwent successful renal transplant and 22.8% died. Conclusion: Hypertensive kidney disease affects all age groups, males more than females. It is commonly associated with other cardiovascular conditions and carries a high morbidity. Vigilant control of blood pressure is recommended.

The Black Kenyan English vowel system

While acoustic phonetic studies have been carried out on all types of Englishes around the world, the second language variety spoken in Kenya has so far not been investigated acoustically. The present paper closes this gap by presenting an acoustic phonetic analysis of acrolectal Kenyan English. The data presented here consist of nine male speakers of acrolectal Kenyan English reading the “The North Wind and the Sun”-passage and were analysed using PRAAT (Boersma 2001; Boersma and Weenink 2008). As I will show, a careful visual and statistical analysis of the data unearthes several features of the Kenyan English vowel system that so far have gone unnoticed (e.g. a trend towards a seven vowel system with two front and two back mid vowels). Furthermore I will argue that some of these features can be traced back to the local L1 feature pool.

Variant origin of the superior thyroid artery in a Kenyan population

Variant anatomy of the superior thyroid artery is important during surgical procedures, interpretation of angiograms, and interventional radiography in the neck. Pattern of the variations shows population differences but there is no data from the Kenyan population. This study therefore investigated the variations in origin of the superior thyroid artery in a Kenyan population. Forty six necks (36 males and 10 females) from 46 cadavers of black Kenyans in Department of Human Anatomy University of Nairobi, Kenya were bilaterally dissected to expose the origin of the superior thyroid artery. Pattern of origin of the vessel was determined on both sides in males and females. It originated from the external carotid artery common carotid artery and linguo-facial trunk in 80%, 13%, and 6.5% of the cadavers respectively on the right side. All but one of the superior thyroid arteries were ventral branches. There was asymmetric origin in 6.5% of cases. Origin from the common carotid artery was associated with high carotid bifurcation. Nearly 20% of superior thyroid arteries showed variant origin. Of these, 6.5% arose from the linguo-facial trunk, much higher than in the Caucasian and Oriental populations. Origin from common carotid artery is substantially lower than prevailing figures from other populations. These findings support ethnic variations. Preoperative angiographic evaluation is recommended.

Angular Photogrammetric Comparison of the Soft-Tissue Facial Profile of Kenyans and Chinese

The purpose of this study was to determine the average angular dimensions that define the normal soft-tissue facial profiles of black Kenyans and Chinese and compare them with each other and with values proposed for whites. Standardized facial profile photographs, taken in natural head position, of 177 black Kenyans and 156 Chinese with normal occlusion and well-balanced faces were analyzed for 12 angular parameters. Two-sample t-tests were used to determine sex and racial differences. Kenyan and Chinese averages were compared with proposed white values using 1-sample t-tests. Eight parameters in Kenyans and 7 in Chinese showed sex differences. All angles, except for facial convexity, nasal dorsum, and inferior facial height, were different between Kenyans and Chinese. Kenyan and Chinese averages for all parameters were different from proposed white average, except for facial convexity. Nasolabial and mentolabial angles showed large individual variability and racial differences. The study demonstrated many differences in average angular measurements of the facial profiles of black Kenyans, Chinese, and white standards. Orthodontists, maxillofacial and plastic surgeons, and other clinicians working in the craniofacial region should bear these in mind when setting aesthetic treatment goals for patients of different races. Mean values from this study can be used for comparison with similar records of subjects with same ethnicity.

Pattern of aneurysms among young black Kenyans

Background Reports on pattern of aneurysms among young people are scanty. These data are important for informing preventive and management strategies. This retrospective study at Kenyatta National Hospital, Nairobi. Kenya describes the pattern of aneurysms among young black Kenyans.

Branching pattern of middle cerebral artery in an African population

Branching pattern of middle cerebral artery influences frequency of its aneurysms, and is of potential value in their surgical repair and diagnosis of stroke. This pattern shows inter-population variations but there is paucity of data from Africans. This study aimed at describing branching pattern among black Kenyans. Middle cerebral arteries numbering 288 from 144 formalin fixed brains obtained during dissection and autopsy at Department of Human Anatomy, University of Nairobi, Kenya were studied. Origin of the middle cerebral artery was identified at base of brain and its stem followed by gently separating the fronto-parietal and temporal lobes. Pattern of early cortical, lenticulostriate, and terminal branching was recorded and macrographs taken. Results were analyzed using SPSS version 13.0 for windows and presented using macrographs. All the brains had bilateral middle cerebral arteries which were continuations of the internal carotid artery. Variations of the artery observed included duplication (1.7%), early bifurcation (5.2%), and early cortical branching (47%), predominantly temporal (63.9%). Lenticulostriate arteries arose predominantly from the pre-bifurcation segment as single branches (64.6%), and as common trunks (35.4%). Modes of termination were bifurcation (82.3%), trifurcation (10.8%), primary trunks (6.2%), and quadrifurcation (0.7%). Cortical branching pattern of the middle cerebral artery resembles that of Caucasian and Indian populations suggesting equal vulnerability to aneurysms and stroke. Pattern of origin of lenticulostriate arteries, predominantly from the pre-bifurcation segment and higher percentage of common trunks implies that the population is more prone to ischemia after aneurysm repair. Extra diligence during operation on proximal middle cerebral artery is called for.

Pediatric stroke in an African country.

Background:The pattern of pediatric stroke displays ethnic and geographical variations. There are few reports from black Sub-Saharan Africa, although relevant data are important in prevention, clinical diagnosis, treatment and prognostication.Aim:To describe subtypes, risk factors, localization, age and gender distribution of pediatric stroke in the black Kenyan population.Study Design and Setting:Retrospective cross-sectional study in a single regional referral and teaching hospital.Statistical Analysis:Data were analyzed by SPSS version 13.0 for Windows and presented in tables and bar and pie charts.Materials and Methods:The study was performed at the Kenyatta National Hospital, a level-6 regional referral health facility with an annual pediatric in-patient turnover of about 40,000 patients. Files of patients aged 1 month to 18 years over a period of 5 years were analyzed for stroke subtypes, localization, risk factors, age and sex distribution. Only those files with complete information were included.Results:Thirty-two of the 712 stroke patients (4.5%) were pediatric. The male:female ratio was 1.7:1. Ischemic stroke comprised 56.3% (n = 18). Mean age was 7.7 years (range, 1.5–18 years). The most common sites were cortical (51%), lacunar (41%) and brain stem (8%). The most common risk factors were connective tissue disorders (28.1%), heart disease (25%), human immunodeficiency virus (9.4%) and infection (9.4%).Conclusion:Pediatric stroke is not uncommon in the Kenyan population. The risk factor profile comprising connective tissue disorders and infection differs from that reported in other populations, inviting large community-based studies.

Non-compliance and formalisation: Mutual accommodation in land subdivision processes in Eldoret, Kenya

Conflicts over land are central to Kenya's political economy. In particular, the displacement of indigenous inhabitants during the process of establishing settler agriculture and the association of dispossession and land claims with particular ethnic groups has continued to fuel conflict and drive government attempts to develop appropriate policies and legislation. Colonial attempts to resolve the problems of overcrowding in 'native reserves' led to a land tenure system based on freehold title, even for African farmers. The concepts of individual title and a commercial land market have, therefore, been embedded in the consciousness of black Kenyans from before independence. In many urban centres, the laws on tenure and subdivision and the prevalence of private ownership have given rise to extreme shortages of land for low-income residential development and conflict over access to undeveloped land. The situation in Eldoret is different. Even though the town is located in the centre of a former settler agri...

Irritable bowel syndrome in Kenyans.

To study the prevalence and clinical presentation of irritable bowel syndrome (IBS) in black Kenyans. A retrospective study. Nairobi Hospital, an urban private institution. Case files of all patients presenting with abdominal pain. Prevalence of IBS using modified Manning's Symptomatic criteria in 223 consecutive adult patients presenting with abdominal pain and discomfort who had normal clinical findings and normal general and gastrointestinal investigations. Out of the 3472 patient files screened, there were 281 patients who fitted the diagnosis of irritable bowel syndrome giving an overall prevalence of 8%. The mean age was 40 years with range of 11 to 75 years with a peak prevalence in the 3rd decade. The male to female ratio of 1.4:1 being statistical significant at a p-value of 0.010. There was no statistical significant difference between the males and females in constipation and diarrhoea at p-value of 0.84 and 0.82 respectively. Fifteen percent of the patients were either on antidepressants or had been seen by a psychiatrist. Nine percent had undergone laparatomy for the abdominal pain. The Black African patient is equally as exposed to irritable bowel syndrome as is his counterpart in the western world and has similar morbidity patterns. The syndrome may account for over 10% of patients with abdominal pain presenting to gastroenterologists in Africa. Proper attention to symptomatology may lead to clinching the diagnosis without resorting to many unnecessary and expensive investigations.

Anatomy and pathology of coronary artery in adult black Kenyans.

To determine the pattern of coronary arterial anatomy and prevalence of postmortem coronary pathology in adult Kenyan Africans. Cross-sectional study. The Nairobi City Mortuary and the Department of Human Anatomy, University of Nairobi. One hundred hearts were retrieved during consecutive autopsies over a three month duration and systematically dissected. Details on coronary ramification, dominance, atherosclerosis, tunnelling and hypoplastic segments were obtained and statistically analysed. Seven patterns of left coronary ramifications were identified. The right coronary artery anomalously exited from the left coronary sinus in one situation. There were separate ostia for the coronary artery branches in 2% and 31 % of cases on the left and right coronary systems respectively. The right coronary artery was dominant in 82% of the hearts. Coronary ostial sizes and luminal dimensions showed wide variations. Only two of the hearts had atheromatous luminal narrowing greater than 75% of the cross-sectional area. Muscle bridges of average depths of 1.1-2 mm were demonstrable in 29% of the autopsies. Diminutive left anterior descending artery was present in four cases. The right coronary artery was diminutive in one case. Coronary atherosclerosis is still a rarity in the setting within which the study was undertaken. The diverse patterns of ramifications of the coronary tree begs for caution during coronary investigations and interventional procedures. Coronary arterial anomalies, myocardial bridges, atheroma and diminutive arteries should be considered in cases of sudden cardiac death in the absence of other pathologies.

Ex vivo antimalarial activity of proguanil combined with dapsone against cycloguanil-resistant Plasmodium falciparum isolates

The ex vivo antimalarial activity of plasma samples obtained from 20 healthy Caucasian volunteers following daily proguanil (200 mg) plus dapsone (8 mg) for malaria chemoprophylaxis inhibited five cycloguanil-resistant Thai isolates of Plasmodium falciparum. All volunteers were phenotyped as extensive metabolisers (EMs) of proguanil. Three of the five isolates were obtained from Thai soldiers who had failed malaria prophylaxis on daily proguanil (200 mg) plus dapsone (4.0 or 12.5 mg). The Thai soldiers were also classified as EMs, but had relatively lower plasma cycloguanil concentrations compared to values reported in the literature for Caucasians and black Kenyans. Although the high level of parasite resistance to cycloguanil was the most likely explanation for the Thai soldiers failing prophylaxis on proguanil plus dapsone, their low cycloguanil concentrations may have also contributed to their lack of protection. However, in areas where parasites are more susceptible to cycloguanil, such as in certain regions of Africa, proguanil plus dapsone may still be an effective chemoprophylactic drug combination.

Variant anatomy of the testicular artery among black Kenyans

Variant anatomy of the testicular artery is important for safe surgery in the retroperioneal area, and accurate diagnosis of testicular and renal disease. The pattern of origin, number, course and branching display ethnic and geographical variations. Data from black African populations and especially Eastern Africa is scarce. The objective of this study was, therefore, to describe the topography of the intraabdominal part of testicular artery in a sample of the Kenyan population. This was a descriptive crosssectional study on one hundred (100) testicular arteries at the Department of Human Anatomy, University of Nairobi. The samples were obtained from autopsy cases and cadaveric specimens. Standard midline abdominal incisions were made, flaps of the anterior abdominal wall reflected and the intestines, mesentery and pariental peritoneum retracted systematically to expose the testicular arteries. Their site and level of origin, number, course and branching were examined. Macrographs of representative variations were taken using a high resolution digital camera. The results were analysed using SPSS version 21, and are presented using macrographs and frequency tables. Thirty three (33%) of the arteries displayed a variant anatomy, with regard to their site of origin (8%), number (4%), course (14%) and branching pattern (7%). Among the 14 cases of aberrant course, five (5%) arched over the left renal vein, eight (8%) were retrocaval and one (1%) had a retroureteric course. Seven (7%) bifurcated within the abdomen. The level of origin along the aorta varied from 1 centimetre above the renal arteries to 5.5 centimetres below them while the vertebral level of origin ranged from T12 to L4. This shows that the testicular artery among Kenyans displays a high prevalence of variant anatomy characterized by origin from the accessory renal artery, high level of aortic origin, duplication, retrocaval course and intraabdominal; division. Preopertaive evaluation of renal and gonadal vasculature is recommended to minimize misdiagnosis and inadvertent injury retroperitoneal surgery.

What is the origin of the labyrinthine artery among black Kenyans?

Origin of labyrinthine artery is important because it influences the presentation of occlusion of anterior inferior cerebellar and basilar arteries. It shows ethnic and geographical variation, but there is no data from black African populations. This study, therefore examined the pattern of origin of labyrinthine artery in adult black Kenyans. Three hundred and fourty six arteries from one hundred and seventy-three formalin fixed brains were examined by dissection at the Department of Human Anatomy University of Nairobi, Kenya. Labyrinthine artery arose from basilar artery in 260 (75.1%); as common trunk with anterior inferior cerebellar artery in 48 (13.9%) and from the latter in 38 (11.0%) of cases. There was no side and gender difference in the pattern of origin. This implies that majority of labyrinthine arteries arise from basilar artery, different from that in oriental, Indo-Asian and Caucasian populations, in which it arises from the anterior inferior cerebellar artery. Preoperative evaluation of basilar artery branching is recommended.Keywords: labyrinthine artery, origin, Kenyan, Basilar, AICA