Evaluation of liposomal nanocarriers loaded with ETB receptor agonist, IRL-1620, using cell-based assays.

One common feature of most neurodegenerative diseases, including Alzheimer's disease (AD) and stroke, is the death of neuronal cells. Neuronal cell death is associated with apoptosis, generation of reactive oxygen species and oxidative stress. Neuronal cell death pathways can be reversed by endothelin B receptor agonist, IRL-1620, which was found to enhance neuroprotection by promoting vascular and neuronal growth in a rodent stroke model. Previous studies conducted at our institution indicated that the treatment with IRL-1620 significantly improved neurological and motor function while reducing oxidative stress and overall infarct area. IRL-1620 is a hydrophilic, 15 amino acid peptide and has a molecular weight of 1820Da. In this study, we have encapsulated IRL-1620 in PEGylated liposomes in order to enhance its efficacy. Each batch of liposomes encapsulating IRL-1620 was evaluated for particle size, polydispersity index, and charge (zeta potential) over a period of time to determine their stability. A dose-response bar graph was plotted based on the effect of neuroprotection by free IRL-1620 on differentiated neuronal PC-12 cells. The 1nM concentration was found to have the highest cell viability. The liposomes loaded with IRL-1620 were tested on differentiated neuronal PC-12 cells for their neuroprotective ability against apoptosis caused by removal of nerve growth factor (NGF) against free (non-encapsulated) IRL-1620. The liposomal IRL-1620 was found to proliferate the growth of serum-deprived differentiated PC-12 cells significantly (p<0.0001). In the western blot analysis, the expression of the anti-apoptotic marker, BCL-2 was found to be increased, and that of pro-apoptotic marker, BAX was found to be decreased with liposomal IRL-1620. The effects were found to be independent of the NGF levels. Finally the free IRL-1620 was found to cause neuronal outgrowth equivalent to the 75ng/ml NGF treatment.

Familial clustering of cancer in two tertiary care hospitals in Nairobi, Kenya.

OBJECTIVE: To describe the occurrence of cancers in families of individuals diagnosed cancer. DESIGN: Cross-sectional descriptive study. SETTING: Outpatient cancer clinics at Kenyatta National Hospital (KNH) and Radiotherapy Clinic at Nairobi Hospital. SUBJECTS: Patients with a tissue histological or cytological diagnosis of cancer. MAIN OUTCOME MEASURES: A reported family history of cancer. RESULTS: A total number of 485 cancer patients were recruited, 382, from KNH and 103 from Nairobi Hospital. These index cases had 45 different types of cancer, with the most common being breast and uterine-cervical malignancies. Prevalence of family history of cancer was found to be 18.8% and was highest among 1st degree relatives. Documentary evidence was seen in 48.4% and history of cancer corroborated by medical personnel in an additional 11%. In 18.7% of cases more than one relative was interviewed to confirm the family history of cancer. Educational levels of the index cases correlated with knowledge of family history of cancer, with those of higher educational level having been more informed about their families' medical history. There was a prevalence of familial cancers of 30% at Nairobi Hospital patients and 15.7% at KNH patients. CONCLUSION: We found the prevalence of family history of cancer in our population to be 18.8% and was highest among 1st degree relatives. This has implications for targeted screening and therefore early diagnosis which is beneficial.

Cooperativity of the MUC1 oncoprotein and STAT1 pathway in poor prognosis human breast cancer.

Signal transducer and activator of transcription 1 (STAT1) is activated in the inflammatory response to interferons. The MUC1 oncoprotein is overexpressed in human breast cancers. Analysis of genes differentially expressed in MUC1-transformed cells has identified a network linking MUC1 and STAT1 that is associated with cellular growth and inflammation. The results further show that the MUC1-C subunit associates with STAT1 in cells and the MUC1-C cytoplasmic domain binds directly to the STAT1 DNA-binding domain. The interaction between MUC1-C and STAT1 is inducible by IFNgamma in non-malignant epithelial cells and constitutive in breast cancer cells. Moreover, the MUC1-STAT1 interaction contributes to the activation of STAT1 target genes, including MUC1 itself. Analysis of two independent databases showed that MUC1 and STAT1 are coexpressed in about 15% of primary human breast tumors. Coexpression of MUC1 and the STAT1 pathway was found to be significantly associated with decreased recurrence-free and overall survival. These findings indicate that (i) MUC1 and STAT1 function in an auto-inductive loop, and (ii) activation of both MUC1 and the STAT1 pathway in breast tumors confers a poor prognosis for patients.

Acute coronary syndromes amongst type 2 diabetics with ischaemic electrocardiograms presenting to accident and emergency department of a Kenyan tertiary institution.

OBJECTIVE: To determine the prevalence of acute coronary syndromes among type 2 diabetic patients presenting to Accident and Emergency department. DESIGN: Prospective cross-sectional study. SETTING: Kenyatta National Hospital, a tertiary teaching and referral hospital. SUBJECTS: Type 2 diabetic patients with ischaemic electrocardiograms (ECG). MAIN OUTCOME MEASURES: Demographics, clinical symptoms, cardiovascular status and risk factors--central obesity, hypertension, dyslipidaemia, smoking. RESULTS: From 12,307 accident and emergency attendees, 400 (33%) diabetics aged > OR =30 years were screened with a resting ECG and 95 (24%) with ischaemic ECG were recruited; age range 41-87 years, 60% were male; diabetes duration ranged 0-30 years with 8.4% being newly diagnosed. The commonest enrolling ECG feature was nonspecific ST-T changes. The commonest presenting complaint were fatigue and dyspnoea. Majority had three coronary artery disease (CAD) risk factors: obesity 86%, elevated LDL 73% and hypertension 60%. Therapy in use was OHA 43%, insulin 42%, insulin and OHA 1%; prophylactic aspirin 14.7% and statins 8.4%. Thirty four (35.8%) were classified as acute coronary syndrome (ACS); 29 (30.5%) acute myocardial infarction (ACS-AMI) and five (5.2%) unstable angina (ACS-UA). Majority (79.4%) of the ACS presented more than six hours after symptom onset and majority had features of acute left ventricular failure. CONCLUSIONS: Acute coronary syndrome accounted for 35% of the morbidity in type 2 diabetics with ischaemic ECG's presenting to KNH accident and emergency department; patients presented late and 80% were not on CAD prophylactic therapy.

Incidence of chemotherapy-related tumour lysis syndrome at Kenyatta National Hospital, Nairobi.

OBJECTIVES: To estimate the magnitude of laboratory defined Tumour Lysis Syndrome (TLS) at Kenyatta National Hospital (KNH), identify its pattern of presentation, resolution, and determine the biochemical outcome of affected patients. DESIGN: Prospective patient-treatment cohort study. SETTING: Kenyatta National Referral and Teaching Hospital, between November 2004 and April 2005. SUBJECTS: One hundred and forty two patients receiving first course chemotherapy. MAIN OUTCOME MEASURE: Laboratory defined Tumour Lysis Syndrome (TLS). RESULTS: One hundred and eleven patients completed the study protocol. Forty two patients (37.8%) developed TLS. The incidence in haematological malignancies was 75.5% while in non-haematological malignancies was 3.6%. Hyperphosphataemia and hyperkalaemia were the most consistent diagnostic parameters while hyperuricaemia occurred in only one patient. No patient developed hypocalcaemia. Ninety five percent of patients developed TLS within the first three days of receiving chemotherapy while 55% resolved in the first week. Two TLS case mortalities occurred. CONCLUSIONS: The incidence of TLS in this cohort study was 38%, and was highest among haematological malignancies. No cases occurred in breast cancer patients. Majority of the cases were diagnosed on the basis of increase in serum phosphate and potassium; uric acid did not rise predominantly due to prophylactic uricosuric therapy. A majority (95%) developed within three days of commencing chemotherapy.

Coronary artery disease and symptoms of depression in a Kenyan population.

BACKGROUND: Depression and heart disease are replacing the traditional enemies of Africa such as infectious diseases and malnutrition as the increasing causes of disability and premature death. Little is known about the co-morbidity of heart disease and depression in Africa. OBJECTIVE: To describe the prevalence of depression in Black Africans with and without Coronary Artery Disease as documented on coronary angiography at the Nairobi Hospital. DESIGN: Prospective comparative study. SETTING: A private not for Profit 210 bed hospital, catering for fee paying middles class clintele. RESULTS: Of the eighteen patients with an abnormal angiogram, the highest score on the BDI was 9 while the average was 2.11. Of the seven with normal angiograms, the highest BDI was 5, and the average was 1.71. There was no statistical significance in these differences. CONCLUSION: While African scientists must continue to concentrate on the urgent medical priorities of today (AIDS, malaria, measles, etc), cognisance has to be made of the other emerging epidemic, of the co-morbidity of coronary artery disease and depression. That no significant difference in depression score between the two groups was found could be due to a number of reasons including the small sample size achieved in this first study of its kind in Kenya.

Complete measurement of the pKa values of the carboxyl and imidazole groups in Bacillus circulans xylanase.

Electrostatic interactions in proteins can be dissected experimentally by determining the pKa values of their constituent ionizable amino acids. To complement previous studies of the glutamic acid and histidine residues in Bacillus circulans xylanase (BCX), we have used NMR methods to measure the pKa s of the seven aspartic acids and the C-terminus of this protein. The pKa s of these carboxyls are all less than the corresponding values observed with random coil polypeptides, indicating that their ionization contributes favorably to the stability of the folded enzyme. In general, the aspartic acids with the most reduced pKa s are those with limited exposure to the solvent and a high degree of conservation among homologous xylanases. Most dramatically, Asp 83 and Asp 101 have pKa s < 2 and thus remain deprotonated in native BCX under all conditions examined. Asp 83 is completely buried, forming a strong salt bridge with Arg 136. In contrast, Asp 101 is located on the surface of the protein, stabilized in the deprotonated form by an extensive network of hydrogen bonds involving an internal water molecule and the neutral side-chain and main-chain atoms of Ser 100 and Thr 145. These data provide a complete experimental database for theoretical studies of the ionization behavior of BCX under acidic conditions.