Level of male infertility in the Ghanaian city of Tema.

Infertility among couples is a sensitive issue in Ghana; females are mostly blamed. Most male infertility cases are generally due to low sperm counts (oligozoospermia), poor sperm quality - characterised by poor sperm motility (asthenozoospermia) - or a combination of both (oligoasthenozoospermia). This is a retrospective study from January 1995 to December 2005 which determined the level and type of male infertility in and around the city of Tema. Seminal fluid analysis reports of male clients who visited the Adom Medical Laboratory in Tema were extracted from laboratory data and analysed. Our study involved 2795 males in the age range of 24-36 years. In 1995, 75% of the total samples analysed had sperm concentrations ranging from 21 to 350 million sperms/ml and showed a decreasing trend to 41% in 2005. Samples with sperm concentrations below 20 million sperms/ml in 1995 increased from 20.5% to 57.6% in 2005; those with active motility > 45% decreased from 27 (30.7%) in 1995 to zero (0%) in 2005, whilst samples with > 50% non-motile sperms increased from 47 (53.4%) in 1995 to 449 (87.7%) in 2005. Male infertility in the samples analysed was due to a combination of oligozoospermia and asthenozoospermia.

Prevalence of hepatitis d infection in patients with hepatitis B virus-related liver diseases in Accra, Ghana.

BACKGROUND: Hepatitis D virus (HDV), a defective RNA virus which depends on hepatitis B virus (HBV) for its replication and expression, appears to be highly pathogenic and modifies the natural history of HBV infection. Two types of infection, co-infection and super-infection are recognised. During infection, anti-delta antibodies appear in serum and can be detected by Enzyme linked Immunosorbent Assay (ELISA). OBJECTIVE: We determined the prevalence of hepatitis D infection amongst HBsAg-positive patients with HBV-related liver diseases in Accra, Ghana using an Enzyme linked Immunosorbent assay (ELISA) method. METHODS: We collected blood samples from 53 patients with hepatitis B-related liver diseases. The sera were analysed using a commercially available kit, the EIA-ANTI-HDV, a third generation ELISA kit (Globe Diagnostics, Italy). RESULTS: There were 39 males (73.6%) and 14 females (26.4%) giving a male:female ratio of about 3:1.The mean age of patients was 38.6 years (range, 15-75). Six patients were reactive for anti-delta antibodies, yielding a HDV sero-prevalence of 11.3%. A higher proportion of males were anti-HDV positive (9.4%) compared to females (1.9%) but the difference was not statistically significant (p=0.350). Anti-HDV was detected in 4(22.2%) patients with chronic hepatitis B, 1(7.6%) with cirrhosis of the liver and 1(5.3%) with hepatocellular carcinoma. CONCLUSION: The prevalence of HDV infection amongst patients with liver disease in Accra with HBV-related liver diseases appears to be high compared to developed countries but similar to several developing countries. No significant difference exists in gender prevalences. A concerted public health effort is required to reduce this high prevalence rate.

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae).

Phyllanthus niruri is a medicinal plant (commonly known as stone breaker) found in the tropics and other parts of the world. It is known for its capacity to block the formation of calcium oxalate crystals and kidney stone formation in urolithiasis. This plant has been used to treat hyperglycemia, hypertension, pain, and mild cases of malaria. We examined the geno-, cyto- and overall toxicity of P. niruri whole plant ethanolic extract. The extract was administered as a single dose of 30 or 300 mg/kg to laboratory rats by gavage, accompanied by negative (0.9% saline) and positive (10 mg/mL N-ethyl-N-nitrosourea) controls that were injected intramuscularly 48 h after extract administration. The ratio of polychromatic (PCE)/normochromatic erythrocytes (NCE) from femur bone marrow was scored for genotoxicity. Cytotoxicity was determined using descending concentrations (0.2-0.0125 g/mL) of the extract incubated with peripheral blood mononuclear cells. Lactate dehydrogenase release from damaged cells was determined and the CC(50) calculated. Subchronic administration of the extract at 30 or 300 mg/kg was done for 90 days to determine general toxicity. PCE:NCE (%) for the extract and negative control was 63, compared to 168 (positive control). The CC(50) was 26.3 mg/mL and hepato-renal toxicity after subchronic extract administration was nil. We conclude that ethanol extract of P. niruri is not cytotoxic or genotoxic, and is generally non-toxic on subchronic administration.

Influence of clinical and demographic factors on static balance among stroke survivors.

BACKGROUND: Stroke is often characterized by disturbance in balance and mobility among the survivors with its attendant rehabilitation potentials. Static balance serves as a foundation for attainment of functions in patients with stroke, yet its determinants are usually under-estimated. AIM: This study was therefore designed to determine the influence of some clinical and demographic factors on static balance in stroke survivors. MATERIAL AND METHODS: Eighty (80) hemiparetic stroke survivors participated in this cross-sectional survey. Demographic variables include age, height, weight and body mass index (BMI) whilst knee range of motion, (ROM) duration of stroke, levels of disability and spasticity of the paretic lower limbs of the participants were the clinical variables. Universal Goniometer, Barthel Index, and Modified Ashworth Scale were used to assess ROM, disability and spasticity levels respectively. The outcome measure for static balance was Functional Reach Test. Pearson's correlation coefficient analysis was performed to establish the correlations between some selected variables and the static balance. Level of significance was set at p<0.05. RESULTS: The mean age of the participants was 56.7+/-12.8 years. They comprised 37(46.2%) right hemiparetic and 43 (53.8%) left hemiparetic patients. Significant positive correlation was observed between functional reach scores and knee ROM, spasticity and disability levels (r=0.3; r=0.5; 0.2) respectively. However, the mean age, weight, height and BMI of the participants were not significantly correlated with functional reach scores. CONCLUSION: Joint range of motion, spasticity and disability levels were the main determinants of static balance in stroke survivors. These factors should be considered whilst priotizing goals during rehabilitation of stroke survivors.

Influence of ethnicity on pharmacogenetic variation in the Ghanaian population.

It has been well established that the frequencies of genomic variants can vary greatly between the populations of different countries. We sought to quantify the intra-population variability in Ghana to determine the value of genotyping studies done at a nationwide level. Further, we investigated the differences between the Ghanaian and other African populations to determine the quality of genomic representation provided by a small subgroup within the continent with regard to the general population. We genotyped 934 unrelated Ghanaian individuals for 15 single nucleotide polymorphisms (SNPs) from genes defined as clinically relevant based on their reported roles in the transport of, metabolism of, or as targets of the medicines listed in the World Health Organization Essential Medicines list. Populations within Ghana and between nations in Western Africa were genetically cohesive. In contrast, populations in other areas of Africa were genetically divergent. Gene allele frequency also differed significantly between the populations in African nations and the United States for several of the SNPs. These results demonstrate that national populations in similar geographic regions, like Africa, may have widely varying genetic allele frequencies for clinically relevant SNPs. Further genotyping studies of specific populations are necessary to provide the best medical care to all individuals.

INTERCOMPARISON ON THE MEASUREMENT OF THE QUANTITY PERSONAL DOSE EQUIVALENT HP(10) IN PHOTON FIELDS. LINEARITY DEPENDENCE, LOWER LIMIT OF DETECTION AND UNCERTAINTY IN MEASUREMENT OF DOSIMETRY SYSTEMS OF INDIVIDUAL MONITORING SERVICES IN GABON AND GHANA.

An inter-comparison study was conducted to assess the capability of dosimetry systems of individual monitoring services (IMSs) in Gabon and Ghana to measure personal dose equivalent Hp(10) in photon fields. The performance indicators assessed were the lower limit of detection, linearity and uncertainty in measurement. Monthly and quarterly recording levels were proposed with corresponding values of 0.08 and 0.025 mSv, and 0.05 and 0.15 mSv for the TLD and OSL systems, respectively. The linearity dependence of the dosimetry systems was performed following the requirement given in the Standard IEC 62387 of the International Electrotechnical Commission (IEC). The results obtained for the two systems were satisfactory. The procedure followed for the uncertainty assessment is the one given in the IEC technical report TR62461. The maximum relative overall uncertainties, in absolute value, expressed in terms of Hp(10), for the TL dosimetry system Harshaw 6600, are 44. 35% for true doses below 0.40 mSv and 36.33% for true doses ≥0.40 mSv. For the OSL dosimetry system microStar, the maximum relative overall uncertainties, in absolute value, are 52.17% for true doses below 0.40 mSv and 37.43% for true doses ≥0.40 mSv. These results are in good agreement with the requirements for accuracy of the International Commission on Radiological protection. When expressing the uncertainties in terms of response, comparison with the IAEA requirements for overall accuracy showed that the uncertainty results were also acceptable. The values of Hp(10) directly measured by the two dosimetry systems showed a significant underestimation for the Harshaw 6600 system, and a slight overestimation for the microStar system. After correction for linearity of the measured doses, the two dosimetry systems gave better and comparable results.

Improving the laboratory diagnosis of TB in Ghana: the impact of a quality assurance system.

SETTING: Greater Accra region, Ghana. OBJECTIVE: To establish a pilot quality assurance (QA) system in sputum smear microscopy and to evaluate its impact. DESIGN: Quarterly supporting visits were paid to participating laboratories between 2000 and 2002. Fifteen examined slides were selected randomly from each laboratory during the visits and blindly re-assessed. Feedback was given promptly to the various laboratories. Training and stakeholder workshops were organised whenever necessary. RESULTS: General improvements in smear preparation and staining as well as the reading ability of the laboratory personnel included in the study were observed. The average marks for specimen quality, staining ability, smear cleanness, thickness, size and evenness increased from 64%, 79%, 69%, 46%, 67% and 60% in the last quarter of 2000 to 81%, 90%, 86%, 79%, 80% and 74%, respectively, 24 months after the establishment of the QA system. Within the same period, the rate of false-positives and -negatives decreased from respectively 14.8% and 20.5% to 0%, and agreements in positivity grade increased from 74% to 95%. The performance of the participating laboratories in keeping the laboratory registers up to date also improved. CONCLUSION: The QA system needs to be extended to the rest of the country.

Situation analysis of TB microscopy centres in Ghana.

SETTING: Public health laboratories in Ghana performing tuberculosis (TB) microscopy. OBJECTIVE: To assess the situation of the laboratories in terms of staff strength, technical skills, documentation, biosafety practices, equipment, supplies and disposal systems. DESIGN: Methods used for data collection were interviews using a structured questionnaire, informal observation of laboratory registers, disposal systems and safety measures for sputum handling. RESULTS: Of 114 laboratories visited between 2000 and 2001, 102 (89.5%) were performing TB microscopy. Of the staff working in the laboratories, 9% were medical technologists, 24% laboratory technicians, 37% laboratory assistants and 30% orderlies. Average false-negative and -positive rates were respectively 13% and 14%. Although most of the centres (85.3%) were using the recommended TB laboratory register for recording, in most cases they were not filled in accurately or completely. The majority of the available microscopes had mechanical or optical faults. Availability of other materials for smear preparation and staining ranged from 44% to 82%. The main methods employed for disposal of laboratory waste were burning and burying, but conditions were poor in most of the facilities visited. CONCLUSION: Training of laboratory personnel in TB microscopy and establishment of a quality assurance system are needed in Ghana.

HTLV-1 and other viral sexually transmitted infections in antenatal and gynaecological patients in Ghana.

BACKGROUND: The study was undertaken to determine the prevalence of infection with Human T cell lymphotrophic (leukemia) virus-1 (HTLV-1), Hepatitis B virus, Hepatitis C virus and Human Immunodeficiency Virus (HIV) in patients attending the antenatal and gynaecological outpatient clinics at Korle-Bu Teaching Hospital (KBTH). DESIGN: Prospective observational survey. Serum from each of the 517 participants was analysed for infection with Hepatitis B surface antigen with a latex agglutination test kit (Biotech Laboratories Ltd., Suffolk, United Kingdom), and tested for antibodies to Human Immunodeficiency Virus (HIV), Hepatitis C virus, and Human T cell lymphotrophic (leukemia) virus-1 (HTLV-1) with SERODIA passive-particle agglutination assay kits (FUJIREDIO Inc., Tokyo, Japan). The results were compared with reports from other institutions. SETTINGS: The Obstetrics and Gynaecology outpatient clinics of the Korle-bu Teaching Hospital, Accra, Ghana. The virology Unit of the Noguchi Memorial Institute for Medical Research (NMIMR), Accra, Ghana. RESULTS: The prevalence of infection with Hepatitis B surface antigen (HBsAg) was 16.8%, Hepatitis C antibody 5.2% and HTLV-1 2.7%. Twelve (6%) out of 199 participants who gave informed consent tested positive for HIV antibody. CONCLUSIONS: The study has demonstrated a high transmissible risk of HBV, HIV, HTLV-1, and HCV in Ghana and the necessity for antenatal screening for HBsAg to identify babies at risk of neonatal hepatitis B infection for appropriate intervention.

Effect of Plasmodium falciparum malaria parasites on haematological parameters in Ghanaian children.

Malaria is hyper-endemic in Ghana. Haematological alterations in the disease pathology may offer complimentary criteria to improve clinical and microscopy diagnosis. Our primary outcome was to evaluate haematological parameters in children with Plasmodium falciparum infections and report their predictive risk and diagnostic performance for malaria infections in Ghana. Haematological data, including thin and thick blood films were examined for children less than 12 years of age in a multicenter-based active case finding approach. Haematological changes were common in P. falciparum infected children and more pronounced in severe malaria cases. More so, a unit increase in parasiteamia increased the odds for severe malaria infection by 93 % [OR, 95 % CI: 1.93 (1.28-2.91); P value = 0.02]. In multivariate regression, low haemoglobin was a significant haematological change in predicting P. falciparum infections [OR, 95 % CI: 3.20 (1.26-7.09); P value = 0.001]. Low haemoglobin levels <11 g/dl was the most reliable indicator for P. falciparum infections [with a sensitivity of (64 %), specificity (71 %), positive predictive value (83 %) and likelihood ratio (2.2)]-even when evaluated in combination with leucocytosis, lymphocytopaenia and high neutrophil counts >7,500 µL. In malaria endemic settings, low haemoglobin concentration (<11 g/dl) in children with febrile illness should prompt a more diligent search for the malarial parasite to limit the misuse and abuse of anti-malarial drugs.

The effect of electronic reminders on risk management among diabetic patients in low resourced settings.

BACKGROUND: Information technology has potential to improve health care delivery particularly among individuals with chronic diseases such as diabetes in low and middle-income countries (LMIC). Research on the usefulness of information technology to manage persons living with chronic diseases is scarce in LMIC. We sought to evaluate the effect of an electronic reminder system on cardiovascular risk factors (blood pressure, heart rate, and fasting plasma glucose) and adherence to clinical appointments among persons living with diabetes. RESEARCH DESIGN AND METHODS: A randomized controlled design was used to recruit 200 diabetic patients (intervention n=100, control n=100) from the National Diabetes Management Research Centre, Accra. All patients received usual diabetes care. The intervention group was given electronic reminders for their clinical appointments and their physicians were prompted with abnormal laboratory results for six months. RESULTS: Baseline characteristics were largely similar for both groups. At six months follow up, the mean reductions of all the cardiovascular risk factors in the intervention group were significantly greater than in the control group: -1.7 kg/m(2) versus -1.1 kg/m(2)(p=0.002) for BMI; -4.7 mmHg versus -2.8 mmHg (p=0.002) for SBP; -5.3 mmH versus -3.1 mmHg (p=0.001) for DBP; -1.7 bpm versus -0.1 bpm (p=0.001) for heart rate and -2.3 mmol/L versus -1.6 mmol/L (p=0.001) for fasting plasma glucose, respectively. Adherence to appointment schedules was also significantly higher in the intervention group compared with the control group (97.8% versus 89.4%, p=0.010). CONCLUSIONS: Locally developed electronic initiatives such as this resulted in improved cardiovascular risk factors and effective compliance to clinical practices and improved quality of care for persons living with diabetes.

Relationship between oxidative stress and haematological indices in patients with diabetes in the Ghanaian population.

BACKGROUND: Persistent hyperglycaemia is a hallmark of Diabetes Mellitus (DM). It causes increased production of free radicals, especially reactive oxygen species (ROS), - resulting in oxidative stress. Reactive Oxygen Species have been implicated in the development of haematological complications in patients with diabetes. Superoxide Dismutase (SOD) is one of the most effective antioxidant enzyme defense systems against free radicals. METHODS: From February through May 2014, we assessed the relationship between oxidative stress and haematological profiles among individuals with and without diabetes. A cross sectional study of 66 case patients and 44 age-matched controls were recruited from the National Diabetes Management and Research Centre (NDMRC), Korle-Bu Teaching Hospital, Accra, Ghana. Blood samples were obtained from study participants with consent. We determined the haematological profiles of study participants and measured their oxidative stress levels using a standardized kit for SOD activity. RESULTS: Higher white blood cell (WBC) counts were seen in the diabetes cohort (p-value = 0.023). The SOD activity tended to be lower in diabetes patients (p-value = 0.144 however) while higher neutrophil levels seemed to correlate with SOD activity (R = 0.249; R2 = 6.2 %; p-value = 0.049). There did not appear to be a correlation between fasting blood glucose (FBG) and SOD activity (R = -0.044; p-value = 0.727). CONCLUSION: The study reports similar oxidative stress levels, as measured by SOD activity, in diabetic and non-diabetic adults. The SOD activity did not appear to correlate with FBG and several other haematological parameters. Further study would be required to investigate the relationship between these haematological indices and diabetic micro- and macro-vascular complications in our population.

Pharmacogenetics of catechol-O-methyltransferase: frequency of low activity allele in a Ghanaian population.

Catechol-O-methyltransferase (COMT) catalyses the O-methylation of neurotransmitters, catechol hormones and drugs such as levodopa and methyldopa. Ethnic differences in COMT activity have been observed in several populations. Previous studies suggest that the g1947G>A low activity allele is less common in individuals of African origin. COMT genotyping was performed using a mini-sequencing method in 195 healthy Ghanaians with a frequency of the homozygous g1947G>A of 6%. This study provides confirmation that the low activity COMT allele is less common in individuals of African origin. This finding may be important clinically with regards to the treatment of many neuropsychiatric disorders and in the pathophysiology of various human disorders including estrogen-induced cancers, Parkinson's disease, depression and hypertension.

Novel thymidylate synthase enhancer region alleles in African populations.

Thymidylate synthase (TS) regulates the production of DNA synthesis precursors and is an important target of cancer chemotherapy. A polymorphic tandem repeat sequence in the enhancer region of the TS promoter was previously described, where the triple repeat gives higher in vitro gene expression than a double repeat. We recently identified ethnic differences in allele frequencies between Caucasian and Asian populations. We now describe assessment of genotype and allele frequencies of the TS polymorphism in 640 African (African American, Ghanaian and Kenyan) and Caucasian (UK, USA) subjects. The double and triple repeat were the predominant alleles in all populations studied. The frequency of the triple repeat allele was similar between Kenyan (49%), Ghanaian (56%), African American (52%), American Caucasian (54%) and British Caucasian (54%) subjects. However, two novel alleles contained 4 and 9 copies of the tandem repeat. These novel alleles were found at a higher allele frequency in African populations (Kenyan 7%, Ghanaian 3%, African American 2%) than Caucasians (UK 1%, USA 0%). The novel alleles identified in this study decrease in frequency with Western migration, while the common alleles are relatively stable. This is a unique example suggesting the influence of multiple selection pressures within individual populations. Hum Mutat 16:528, 2000.

Analysis of the CYP2D6 gene mutations and their consequences for enzyme function in a West African population.

The data on differences in the metabolic handling of the CYP2D6 probe drugs sparteine and debrisoquine, and the relationship between phenotype and genotype and gene frequencies for several mutant CYP2D6 alleles in African populations are limited and sometimes controversial. Therefore, in a West African population (Ghana), we investigated (i) the phenotype for sparteine debrisoquine by phenotyping 201 individuals with both drugs and (iii) the genotype for CYP2D6 (n = 326) and debrisoquine (n = 201) oxidation, (ii) the coregulatory control of sparteine and alleles *3 and *4 in 133 individuals and for the alleles *1, *2, *3, *4, *5, *6, *7, *8, *9, *10, *14, *16, *17, *2b, *2xN, *2bxN in 193 individuals. Of the 326 individuals phenotyped with sparteine, eight had a metabolic ratio (MR)sp > 20 corresponding to a poor metabolizer frequency of 2.5% [95% (confidence interval) CI = 1.06-4.77]. The prevalence of the poor metabolizer phenotype for debrisoquine oxidation was 3% (95% CI = 1.1-6.39) with six of the 201 individuals having a MR greater than 12.6. The distribution of the MR of sparteine was trimodal whereas MR of debrisoquine was unimodally distributed with a pronounced kurtosis. In individuals phenotyped with both drugs, there was a significant correlation between the MRs (r(s) = 0.63, P < 0.001). The CYP2D6 alleles *1, *2 and *17 were the most common functional alleles occurring with frequencies of 43.7, 10.6 and 27.7%, respectively. The three other observed functional alleles *2xN, *10 and *20 had much lower frequencies (1.6%, 3.1% and 0.3%, respectively). Of the eight non-functional alleles, only *4 (6.3%) and *5 (6.0%) could be found. The allele *5 occurred with the same frequency as in Caucasian populations (4.1%) but the *4 allele had a much lower frequency (Caucasians 19.5%). One individual with *1/*1 was a poor metabolizer for sparteine and debrisoquine indicating the existence of as yet unknown non-functional alleles in this West African population. Although the prevalence of poor metabolizers and the number of heterozygotes for non-functional alleles was much lower in Ghanaians, the median MRsp of 0.7 was significantly higher in this population compared with a median MRsp of 0.4 in Caucasians, indicating a lower metabolic clearance for CYP2D6 substrates in the West Africans. The lower metabolic activity in Ghanaians could not be explained solely by the high frequency of the *17 allele, which is associated with an impairment of CYP2D6 enzyme function. In addition, a higher median MRsp of 0.5 corresponding to metabolic clearance of 346 ml/min was observed among extensive metabolizers with the genotype *1/*1. Thus, compared with the median of MRsp = 0.28 (CLmet 573 ml/min) in Caucasians homozygous for *1, the metabolic clearance of sparteine was 40% lower on average in respective Ghanaians.

MDR1 pharmacogenetics: frequency of the C3435T mutation in exon 26 is significantly influenced by ethnicity.

P-glycoprotein (PGP), the product of the multidrug resistance gene (MDR1), acts as an energy-dependent efflux pump that exports its substrates out of the cell. PGP expression is an important factor regulating absorption of a wide variety of medications. It has also been associated with intrinsic and acquired cross resistance to a number of structurally unrelated anticancer drugs. A single nucleotide polymorphism (SNP) in exon 26 of the MDR1 gene, C3435T, was recently correlated with PGP protein levels and substrate uptake. Individuals homozygous for the T allele have more than four-fold lower PGP expression compared with CC individuals. As overexpression of PGP has been associated with altered drug absorption, therapy-resistant malignancies, and lower concentrations of HIV-1 protease inhibitors, this SNP may provide a useful approach to individualize therapy. To facilitate clinical application throughout the world, 1280 subjects from 10 different ethnic groups were evaluated for this SNP using the polymerase chain reaction-restriction fragment length polymorphism assay and the genotype and allele frequency for each group were ascertained. Marked differences in genotype and allele frequency were apparent between the African populations and the Caucasian/Asian populations (P < 0.0001). The Ghanaian, Kenyan, African American and Sudanese populations studied had frequencies of 83%, 83%, 84% and 73%, respectively, for the C allele. The British Caucasian, Portuguese, South-west Asian, Chinese, Filipino and Saudi populations had lower frequencies of the C allele compared to the African group (48%, 43%, 34%, 53%, 59%, and 55%, respectively). The high frequency of the C allele in the African group implies overexpression of PGP and may have important therapeutic and prognostic implications for use of PGP dependent drugs in individuals of African origin.

Circadian variation of platelet 3H-imipramine binding, platelet serotonin content, and plasma cortisol in healthy volunteers.

Platelet 3H-imipramine binding, platelet serotonin content, and plasma cortisol were measured in 10 healthy female volunteers. Samples were taken on 5 occasions with a 6-hr interval during a 24-hr period within 1 week in May. Although there were individual variations in the biochemical parameters over a 24-hr period, we could not establish a clear common circadian rhythm for all subjects in platelet 3H-imipramine binding and platelet serotonin concentrations. During the night, there was a significant decrease in Bmax values and a slight, but not significant, increase in serotonin concentrations. A distinct circadian rhythm was obtained for plasma cortisol, with lowest values during the night.

Two approximately 300 kilodalton Plasmodium falciparum proteins at the surface membrane of infected erythrocytes.

Two very large Plasmodium falciparum proteins are identified as constituents of the infected erythrocyte membrane. Sera were obtained from Aotus monkeys that had been repeatedly infected with asexual P. falciparum from one of four strains. The capacity of these sera to block in vitro cytoadherence of infected erythrocytes and agglutinate intact infected cells was determined. The sera were also used to immunoprecipitate protein antigens from detergent extracts of 125I-surface labeled or biosynthetically radiolabeled infected erythrocytes. For each serum/antigen combination, precipitation of only one protein correlated with the ability of the serum to interfere with cytoadherence and agglutinate infected cells. This malarial protein, denoted Pf EMP 1 (P. falciparum-erythrocyte-membrane-protein 1) bore strain-specific epitope(s) on the cell surface and displayed size heterogeneity (Mr approximately 220,000-350,000). Pf EMP 1 was strongly labeled by cell-surface radioiodination but was a quantitatively very minor malarial protein. Pf EMP 1 was distinguished by its size, surface accessibility and antigenic properties from a more predominant malarial protein in the same size range (Pf EMP 2) that is under the infected erythrocyte membrane at knobs. Monoclonal antibodies and rabbit antisera raised against Pf EMP 2 were used to show that this size heterogeneous antigen was indistinguishable from the previously described MESA (mature parasite infected erythrocyte surface antigen), identified by precipitation with rabbit antisera raised against the MESA hexapeptide repeats. Antibodies raised against Pf EMP 2/MESA did not precipitate Pf EMP 1. We conclude that Pf EMP 1 is either directly responsible for the cytoadherence phenomenon, or is very closely associated with another as yet unidentified functional molecule. Pf EMP 2/MESA must have a structural property/function that is important under the host cell membrane.

Plasmodium falciparum: sensitivity to chloroquine in vivo in three ecological zones in Ghana.

4690 children aged 6-15 years in 5 urban and 4 rural communities in 3 ecological zones in Ghana were screened from June 1988 to December 1990 to provide suitable candidates for the World Health Organization standard in vivo test for susceptibility of Plasmodium falciparum to chloroquine. 1880 (40.1%) had parasitaemia, mostly (83.7-98.6%) due to P. falciparum infection. Of the 626 in vivo tests performed, 570 (91.1%) showed sensitivity to chloroquine and 56 (8.9%) responses were classified as resistant to chloroquine at RI (5.1%) and RII (3.8%). The resistance responses were commonest (17.1-22.7%) in the coastal zone, followed by the savanna zone (8.6-10.0%), and lowest in the forest zone (3.1-6.3%). The RII responses occurred mainly in communities in the coastal zone. There was no RIII resistance in any zone. The pattern of RI (early) and RII responses of P. falciparum to chloroquine in this study suggested an increase in sensitivity, or a reduction in resistance, of P. falciparum to chloroquine from the coast to the forest and northern savanna zones, and from the urban to the rural communities in each zone in Ghana.