Trends in extrapulmonary TB cases at three teaching hospitals in Ghana, 2008-2017.

SETTING: Three teaching hospitals in Ghana. OBJECTIVE: To elucidate trends in demographics, clinical characteristics and treatment outcomes in extrapulmonary TB (EPTB) patients. DESIGN: This was a retrospective study involving the review and comparison of EPTB and pulmonary TB (PTB) data from 1 January 2008 to 31 December 2017 in TB registers and treatment cards. RESULTS: Of 15,392 TB cases, 4607 (30%) were EPTB, including 4477/4607 (97%) new cases. There were 2,679/4607 (58%) males and the age range was 0.3 to 96 years. Pleural TB (1021/4607, 22%) was the most common. Treatment success rates for EPTB and PTB were respectively 72% and 84%. HIV positivity was high among patients with disseminated/miliary TB (429/779, 55%) and TB meningitis (242/526, 46%). To note, disseminated/miliary TB (χ2 = 33.53, P < 0.0001) increased, whereas TB meningitis (χ2 = 19.43, P < 0.0001) decreased over the 10-year period. Mortality among EPTB patients was associated with increasing age (⩾25 years), disseminated/miliary TB, TB meningitis and HIV positivity. CONCLUSIONS: There is male preponderance for both EPTB and PTB in Ghana. Increasing age, disseminated/ miliary TB, TB meningitis and HIV are risk factors for mortality among EPTB patients. This emphasises the need for public education on the risk factors for EPTB and preventive strategies.

CONTEXTE: Trois centres hospitalières universitaires au Ghana. OBJECTIF: Elucider les tendances démographiques, les caractéristiques cliniques et les résultats du traitement de patients atteints de TB extrapulmonaire (EPTB) au Ghana. SCHEMA: Ceci est une étude rétrospective de revue et de comparaison des données de EPTB et de TB pulmonaire (PTB) du 1e janvier 2008 au 31 décembre 2017 dans les registres de TB et les cartes de traitement. RESULTATS: Sur 15 392 cas de TB, 4607 (30%) étaient des EPTB dont 4477/4607 (97%) étaient de nouveaux cas. Les hommes représentaient 2679/4607 (58%) et leur âge allait de 0,3 à 96 ans. Une TB pleurale 1021/4607 (22%) était la plus fréquente. Le taux de réussite du traitement de la EPTB et de la PTB a été de 72% et 84%, respectivement. La positivité au VIH était élevée parmi les patients atteints de TB disséminée/miliaire (429/779 ; 55%) et de méningite tuberculeuse (242/526 ; 46%). Il est significatif que la TB disséminée/miliaire (χ2 = 33,53 ; P < 0,0001) a augmenté tandis que la méningite TB (χ2 = 19,43, P < 0,0001) a diminué au long de la période de 10 ans. La mortalité des patients EPTB a été associée à un âge croissant (≥25 ans), une forme disséminée/miliaire, à une méningite TB et à la positivité au VIH. CONCLUSIONS: Il y a une prépondérance masculine à la fois de la EPTB et de la PTB au Ghana. Un âge croissant, une forme disséminée/ miliaire, une méningite TB et le VIH sont des facteurs de risque de mortalité pour les patients EPTB. Ceci met l'accent sur le besoin d'éducation du public relative aux facteurs de risque et aux stratégies de prévention.

A molecular understanding of magnesium aluminium silicate - drug, drug - polymer, magnesium aluminium silicate - polymer nanocomposite complex interactions in modulating drug release: Towards zero order release.

This study reports the use of ITC in understanding the thermodynamics occurring for a controlled release system in which complexation has been exploited. In this study, a model drug, propranolol hydrochloride (PPN) was complexed with magnesium aluminium silicate (MAS) and these complexes were used in combination with polyethylene oxide (PEO) as a hydrophilic carrier at various concentrations to sustain the release of PPN. DSC, XRPD, ATR-FTIR and SEM/EDX were successfully used in characterising the produced complexes. 2D- SAXS data patterns for MAS and the produced complexes were shown to be symmetric and circular with the particles showing no preferred orientation at the nanometre scale. ITC studies showed differences between PPN adsorption onto MAS compared with PPN adsorption onto a MAS-PEO mixture. At both temperatures studied the binding affinity Ka was greater for the titration of PPN into the MAS-PEO mixture (5.37E + 04 ± 7.54E + 03 M at 25 °C and 8.63E + 04 ± 6.11E + 03 M at 37 °C), compared to the affinity obtained upon binding between PPN and MAS as previously reported suggesting a stronger binding with implications for the dissolution process. MAS-PPN complexes with the PEO polymer compacts displayed desired manufacturing and formulation properties for a formulator including, reduced plastic recovery therefore potentially reducing the risk of cracking/splitting and on tooling wear, controlled release of PPN at a significantly low (5%) polymer level as well as a zero-order release profile (case II transport) using up to 50% polymer level.

Expression of Tumour-Associated MUC1 Is a Poor Prognostic Marker in Breast Cancer in Kumasi, Ghana.

BACKGROUND: Immunohistochemical assessment of breast cancer and stratification into the basic molecular subtypes afford a much deeper insight into the biology of breast cancer, while presenting with opportunities to exploit personalized, targeted treatment. Traditionally, the oestrogen, progesterone, and epidermal growth factor receptors are assessed. MUC1, a transmembrane mucin, has been demonstrated a potential prognostic and metastatic marker in breast cancer. However, there have been a limited number of studies addressing the predictive and prognostic features of MUC1 in African breast cancer. This study aims at addressing the expression profiles of MUC1 and other biomarkers in Ghanaian breast cancer and determines its predictive and prognostic characteristics, in relation to other clinicopathological features. METHODS: Haematoxylin and eosin (H&E) slides of breast cancer cases were reviewed and 203 suitable cases were selected for tissue microarray (TMA) construction and immunohistochemistry. Anti-ER, PR, HER2, Ki-67, and MUC1 antibodies were used. Results from the immunostaining were analysed using SPSS version 23. RESULTS: About 59% of cases expressed MUC1. Majority of cases in the study showed a lack of expression of all three traditional markers (29% expressed ER, 10.9% PR, and 20.7% HER2). Ki-67 index were 62.1% (low), 16.5% (moderate), and 21.4% (high). MUC1 expressions among the molecular classes were luminal A (60.7%), luminal B (68.8%), HER2 overexpression (87.5%), and triple negative (56.6%). There were significant associations between MUC1 and HER2 overexpression (p=0.01) and triple negative (p < 0.01). CONCLUSION: The high proportion of breast cancer cases expressing MUC1, as well as its association with the two most aggressive molecular classes, indicate a substantial role in the biology of breast cancer in our cohort, and it is an indication of poor prognosis.

National population-based tuberculosis prevalence survey in Ghana, 2013.

BACKGROUND: The prevalence of tuberculosis (TB) disease is one of the three main indicators used to assess the epidemiological burden of TB and the impact change of TB control; the other two are incidence and mortality.OBJECTIVE: To estimate the prevalence of TB disease among adults in Ghana.METHODS: A nationally representative cross-sectional survey was conducted. Participants were screened for TB using interview and chest X-ray (CXR). For those participants with cough ≥2 weeks and/or abnormal CXR, spot and morning sputum specimens were collected and examined by smear microscopy and culture.RESULTS: The study revealed that the prevalence of smear-positive TB among adults (age ≥15 years) was 111 (95%CI 76-145) and that of bacteriologically confirmed TB was 356 (95%CI 288-425) per 100 000 population. Males and older people had a higher prevalence than their counterparts. The majority of TB cases were smear-negative and had an abnormal CXR without reported chronic cough.CONCLUSION: The survey revealed much higher TB disease burden than previously estimated. This implies that the programme needs more effort and resources to find undiagnosed and unreported cases. The higher proportion of smear-negative and asymptomatic TB cases suggests the need to revise the existing screening and diagnostic algorithms.

Mechanical and release behaviour of theophylline from matrix tablets containing psyllium powder in combination with grewia polysaccharides.

This study was aimed at investigating the effect of grewia polysaccharides on the mechanical and release properties of tablet matrices containing binary mixtures of the polysaccharide with psyllium. Two grades of grewia polysaccharides (GG and GDS) were extracted and binary mixtures of the polysaccharides with psyllium were formulated into tablet matrices containing theophylline as the model drug. The true, bulk and tapped densities, Carr's compressibility index of the powders and binary composites were determined before tablet compression. Tablet properties (hardness, porosity, and drug release from the matrices) were investigated. The dissolution test was carried out in 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The results show that GG and GDS produced tablets with good mechanical strength (108.33 N and 95.70 N, respectively) while psyllium produced softer tablets (7.13 N). The combination of psyllium and grewia polysaccharides in the matrices resulted in a significant increase in the mechanical strength of the matrices when compared to matrices containing psyllium alone as the matrix former. The results also showed that GG and GDS reduced the dissolution rate and effectively eliminated the burst release of theophylline from the psyllium matrices at both pHs. The matrices of GG or GDS and the binary mixtures conform to non-Fickian anomalous diffusion with n > 0.45. When overcoming the burst release of drug from matrices such as psyllium, grewia polysaccharides may provide an effective reduction and a more sustained drug release from such matrices.

Real time calorimetric characterisation of clay - drug complex dispersions and particles.

Isothermal titration calorimetry (ITC) along with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and high-performance liquid chromatography (HPLC) were employed to investigate the process of adsorption of propranolol hydrochloride (PPN) onto magnesium aluminium silicate (MAS) and to characterise the MAS-PPN particles formed upon complexation. The composition of MAS was confirmed by infrared (IR) spectroscopy and a calcimeter. The calorimetric results confirmed the binding between PPN and MAS at various pHs and temperatures. The overall change in enthalpy was found to be exothermic with a comparatively small entropic contribution to the total change in Gibbs free energy. These findings suggest that the binding process was enthalpically driven and entropically unfavourable (lower affinity) suggesting hydrogen bonding and electrostatic interactions dominating the interaction. The variation of pH and temperature did not have a great impact on the thermodynamics of the binding process, as observed from the similarity in enthalpy (ΔH), entropy (ΔS) or Gibbs free energy (ΔG). A slight reduction in the binding affinity (Ka) with varing pH and temperature was however observed. SEM/EDX studies showed the occurrence of changes in the microstructural properties of MAS following complexation which may explain the potential of MAS-PPN complexes for controlled drug release promoting pharmaceutical innovation.

Hydro-alcoholic media effects on theophylline release from sesamum polysaccharide gum matrices.

Concomitant ingestion of alcohol and medications can greatly affect drug plasma concentrations as dose dumping or failure may occur as a result of the fact that formulation excipients may not always be resistant to alcohol. In this study, a natural polysaccharide (Sesamum radiatum gum) (SG) was extracted, characterized and used to formulate sustained release theophylline compacts to study the effect of varying alcohol concentrations (v/v) in dissolution media on drug release from these compacts. X-ray powder diffraction showed that the extracted gum was amorphous in nature with the powder having excellent compaction properties as observed with its compact being significantly harder than those prepared with pure hydroxypropyl methyl cellulose (HPMC) K4M. X-ray microtomography showed that the compacts produced were homogenous in nature, however, swelling studies showed failure of the compacts at the highest concentration of absolute ethanol used (40% v/v). Dissolution studies showed similarity at all levels of alcohol tested (f2 = 57-91) in simulated gastric (0.1 N HCl, pH 1.2) and intestinal fluids (phosphate buffer, pH 6.8) for the HPMC compacts whereas dissimilarity only occurred for the SG compacts at the highest alcohol concentration in both media (f2 = 35). The suitability of SG as a matrix former that can resist alcoholic effects therefore makes it suitable as an alternative polymer with wider applications for drug delivery.

The influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets.

Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375N) than that of the native polysaccharide (82N) and HPMC K4M (146N). Dissolution studies showed similarity at all levels of alcohol tested (f2=57-91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar (f2=60-94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) (f2=43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.

THE PREVALENCE OF TUBERCULOSIS IN CATTLE AND THEIR HANDLERS IN NORTH TONGU, VOLTA REGION, GHANA.

BACKGROUND: The need to understand the contribution of bovine tuberculosis (BTB) to the general tuberculosis burden in a poor resource setting is paramount. The aim of this study is to determine the burden of BTB among herdsmen and cattle in the North Tongu district of Volta Region in Ghana. MATERIALS AND METHODS: A cross- sectional study was conducted in the North Tongu District of the Volta Region between the period of October 2011- March 2012. A well-structured questionnaire was used to collect socio-demographic information and possible risk factor information on cattle from participants. Sputum samples from 68 herdsmen and blood samples from 200 cattle belonging to these herdsmen were also collected. Sputum samples were analyzed using Ziehl- Neelsen staining while Anigen Rapid BTB Test was used for Cattle blood samples. RESULTS: Ninety percent (61/68) of respondents were also found to consume fresh milk while 84% (57/68) do not use protective clothing. Of a total of 1580 cattle owned by the herdsmen, 200 cattle consisting of 14 bulls and 186 cows were screened where the prevalence of bovine TB was 19% (38/200) and those affected were all females. All (100%) human sample tested negative for Acid-Fast Bacilli (AFB). However, the seropositivity of cattle and kraal density were statistically associated (p= 0.001). CONCLUSION: Bovine TB is prevalent in cattle in North Tongu district. Although herdsmen indulge in risky lifestyles that expose them to BTB, a zero prevalence of BTB was observed, further study is envisaged using a larger sample size.

Starch-free grewia gum matrices: Compaction, swelling, erosion and drug release behaviour.

Polysaccharides are suitable for application as hydrophilic matrices because of their ability to hydrate and swell upon contact with fluids, forming a gel layer which controls drug release. When extracted from plants, polysaccharides often contain significant quantities of starch that impacts upon their functional properties. This study aimed to evaluate differences in swelling, erosion and drug release from matrix tablets prepared from grewia gum (GG) and starch-free grewia gum (GDS) extracted from the stems of Grewia mollis. HPMC was used as a control polymer with theophylline as a model drug. Swelling, erosion, and in-vitro release were performed in deionized water, pH 1.2 and pH 6.8 media. The Vergnaud and Krosmeyer-Peppas model were used for swelling and drug release kinetics, respectively. However, linear regression technique was used to determine the erosion rate. GDS compacts were significantly harder than the native GG and HPMC compacts. GDS matrices exhibited the fastest erosion and drug release in deionised water and phosphate buffer compared with the GG and HPMC. At pH 1.2, GDS exhibited greater swelling than erosion, and drug release was similar to GG and HPMC. This highlights the potential of GDS as a matrix for controlled release similar to HPMC and GG at pH 1.2 but with a more rapid release at pH 6.8. GDS may have wider application in reinforcing compacts with relatively low mechanical strength.

Microbiological quality and antibiotic residues in informally marketed raw cow milk within the coastal savannah zone of Ghana.

OBJECTIVES: To investigate the microbiological quality and the presence of antibiotic residues in raw cow milk and in some indigenous milk products produced and marketed by the informal sector in the coastal savannah zone of Ghana. METHODS: Milk samples were aseptically collected from 224 kraals and samples of 26 indigenous milk products were purchased from processors and retailers. Total plate counts, total coliform counts and the presence of Escherichia coli and E. coli O157:H7 were determined in all 250 samples. Milk samples were also tested for antibiotic residues. RESULTS: Total plate counts exceeded 105 CFU/ml in 45.2% of the samples while coliforms exceeded 10³ CFU/ml in 66.0% and E. coli was detected in 11.2%. E. coli was present in raw cow milk but not in the indigenous products and all E. coli isolates were negative for E. coli O157:H7. Antibiotic residues were detected in 3.1% of the raw cow milk samples. CONCLUSION: Bulk milk contains unacceptable levels of hygiene indicators and antibiotic residues and is a potential source of milk-borne infections. The detection of E. coli and antibiotic residues raises public health concerns about the safety of fresh unpasteurized cow milk in the coastal savannah zone of Ghana and calls for improved farm hygiene, the need for milk pasteurization and the sensible use of antibiotics in the milk industry.

Diagnosis of tuberculosis in ghana: the role of laboratory training.

OBJECTIVES: The laboratory is considered the cornerstone of tuberculosis (TB) control programme. International review of Ghana's programme in the late nineties identified the laboratory services as the weakest component. Sputum smear microscopy (SSM) being the main method of diagnosing pulmonary TB in Ghana, the training objectives were to: (i) strengthen the knowledge and skills of laboratory personnel on SSM (ii) impart necessary techniques in biosafety and (iii) introduce a Quality Assurance (QA) system in order to strengthen SSM services. METHODS: Personnel were selected for training during a nationwide situation analysis of SSM centres in 2000/2001. Four training sessions on SSM/QA were held between 2001/2004. RESULTS: A total of 80 personnel were trained: 10 regional TB coordinators and 70 laboratory personnel. The participants upon return to their respective regions also organized training within their districts. This approach resulted in another 100 district TB coordinators and 200 laboratory personnel being trained. Improvement in smear preparation, staining and reading ability of the participants were observed during the post-test and subsequent visit to their respective laboratories. The training has led to strengthening of TB laboratory services in the country and has contributed to increase in case detection from 10,745 in 2000 to 11,827 in 2004 and 14,022 in 2008. It was observed during the post-training follow-up and quarterly supervision visits that morale of the personnel was high. CONCLUSION: Continuous training and re-training of laboratory personnel on SSM and QA at regular intervals do play an important role for effective and efficient TB control programme.

Culture and sensitivity of mycobacterial isolates from cases of pulmonary tuberculosis classified as treatment failures in a teaching hospital.

BACKGROUND: The level of drug resistance in mycobacterial isolates from previously treated cases in Ghana is not known although drug resistant tuberculosis threatens efforts to control the disease. OBJECTIVE: To identify and determine the susceptibility of mycobacterial isolates from tuberculosis cases with clinical treatment failure. METHODS: This prospective survey was undertaken at the Chest Clinic of Korle Bu Teaching Hospital in Accra, Ghana. The participants were twenty-eight cases referred to the hospital with clinical treatment failure. Two sputum specimens from each case were stained by Ziehl-Neelsen method, cultured, identified and sensitivity tests performed by the proportion method. RESULTS: Eighteen isolates of mycobacteria were identified from 28 failed treatment cases. Five were atypical mycobacteria. Approximately fifty percent (13/28) of cases had Mycobacterium tuberculosis, 5(18%) had atypical mycobacteria, 7(25%) had pure fungal growth and 3(11% 8) had no growth. Fifteen isolates were resistant to two or more drugs, of which 6 were resistant to all four drugs tested. CONCLUSION: Continuous drug resistance monitoring must be instituted as part of the tuberculosis control programme.

Patterns of [Ca2+](i) mobilization and cell response in human spermatozoa exposed to progesterone.

Human spermatozoa stimulated with progesterone (a product of the cumulus and thus encountered by sperm prior to fertilization in vivo) apparently mobilize Ca(2+) and respond very differently according to the way in which the steroid is presented. A progesterone concentration ramp (0-3 microM) induces [Ca(2+)](i) oscillations (repetitive store mobilization) which modify flagellar beating, whereas bolus application of micromolar progesterone causes a single large transient (causing acrosome reaction) which is apparently dependent upon Ca(2+) influx. We have investigated Ca(2+)-mobilization and functional responses in human sperm exposed to 3 muM progesterone. The [Ca(2+)](i) response to progesterone was abolished by 4 min incubation in 0 Ca(2+) medium (2 mM EGTA) but in nominally Ca(2+)-free medium (no added Ca(2+); 0 EGTA) a smaller, slow response occurred. Single cell imaging showed a similar effect of nominally Ca(2+)-free medium and approximately 5% of cells generated a small transient even in the presence of EGTA. When cells were exposed to EGTA-containing saline (5 min) and then returned to nominally Ca(2+)-free medium before stimulation, the [Ca(2+)](i) transient was greatly delayed (approximately 50 s) and rise time was doubled in comparison to cells not subjected to EGTA pre-treatment. We conclude that mobilization of stored Ca(2+) contributes a 'slow' component to the progesterone-induced [Ca(2+)](i) transient and that incubation in EGTA-buffered saline is able rapidly to deplete this store. Analysis of flagellar activity induced by 3 muM progesterone showed an effect (modified beating) associated with the [Ca(2+)](i) transient, in >80% of cells bathed in nominally Ca(2+)-free medium. This was reduced greatly in cells subjected to 5 min EGTA pre-treatment. The store-mediated transient showed a pharmacological sensitivity similar to that of progesterone-induced [Ca(2+)](i) oscillations (consistent with filling of the store by an SPCA) suggesting that the transient induced by micromolar progesterone is a 'single shot' activation of the same store that generates Ca(2+) oscillations.

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.

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.

Bicarbonate and bovine serum albumin reversibly 'switch' capacitation-induced events in human spermatozoa.

We have investigated the reversibility of biochemical and physiological changes that occur upon suspension of ejaculated human spermatozoa during in vitro capacitation. Cells were swum up in a simple HEPES-based saline [lacking bicarbonate and bovine serum albumin (BSA)], then resuspended either in supplemented Earle's balanced salt solution (sEBSS) (25 mM bicarbonate) with 0.3% BSA (for in vitro capacitation) or in medium-lacking bicarbonate and/or BSA. Progesterone-induced acrosome reaction (AR) developed during in vitro capacitation (6 h). A progesterone-induced [Ca2+]i signal was detectable in cells maintained in the simple HEPES-based saline, but upon transfer to sEBSS, the response increased three- to four-fold, saturating within <30 min. Serine/threonine phosphorylation saturated within minutes of resuspension, but tyrosine phosphorylation developed over 3 h. Return of cells to non-capacitating conditions caused reversal of all capacitation-dependent changes. The [Ca2+]i signal reverted to its 'uncapacitated' size within <30 min. Protein phosphorylation reversed gradually and could be reinduced (kinetics resembling the first response) upon resuspension in sEBSS. The ability of cells to undergo progesterone-induced AR fell to levels similar to those in uncapacitated cells within 1 h of resuspension in medium not supporting capacitation. Loss of protein phosphorylation occurred only in the absence of both bicarbonate and BSA, but effects on [Ca2+]i signalling and AR could be seen after removal of only one of these factors. We conclude that key events in the capacitation of human spermatozoa are both reversible and repeatable.