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Biomedical subjects

V P Titanji

Publications and source records attributed to V P Titanji.

At least 19 recordsLinked to original sources
PubMed2003

Antibiogram and plasmid profiles of Neisseria gonorrhoeae isolates from Cameroon: useful tools for epidemiological survey.

A prospective laboratory-based investigative study was carried out on clinical isolates of N. gonorrhoea to determine their antibiotic susceptibility patterns and plasmid profile using standard microbiological and molecular techniques. All the 32 isolates studied showed total resistance to penicillin, spectinomycin and amoxyclinE. On the other hand, susceptibilities of 100%, 98.6% and 98.6% were noted for ciprofloxacin, ofloxacin and norfloxacin respectively. Thirty (93.8%) of the 32 isolates were found to harbour plasmids of molecular weights ranging from 9.2 to 25.2 Mdal. Three distinct groups of N. gonorrhoea isolates were identified based on the molecular weights of the plasmids, namely, group one (9.2 Mdal), group two (12.6 Mdal) and group three (25.2 Mdal). These results suggest that different strains of N. gonorrhoea may be circulating in Fako Division of Cameroon, a finding that is of clinical and epidemiological significance.

Cameroon↗
PubMed2001

Genetic variability and linkage disequilibrium within the HLA-DP region: analysis of 15 different populations.

In order to understand the forces governing the evolution of the genetic diversity in the HLA-DP molecule, polymerase chain reaction (PCR)-based methods were used to characterize genetic variation at the DPA1 and DPB1 loci encoding this heterodimer on 2,807 chromosomes from 15 different populations including individuals of African, Asian, Amerindian, Indian and European origin. These ethnically diverse samples represent a variety of population substructures and include small, isolated populations as well as larger, presumably admixed populations. Ten DPA1 and 39 DPB1 alleles were identified and observed on 87 distinct DP haplotypes, 34 of which were found to be in significant positive linkage disequilibrium in at least one population. Some haplotypes were found in all ethnic groups while others were confined to a single ethnic group or population. Strong positive global linkage disequilibrium (Wn) between DPA1 and DPB1 was present in all 15 populations. The African populations displayed the lowest values of Wn whereas the Amerindian populations displayed near absolute disequilibrium. Analysis of the distribution of haplotypes using the normalized deviate of the Ewens-Watterson homozygosity statistic, F, suggests that DP haplotypes encoding the functional heterodimer are subject to much lower degrees of balancing selection than other loci within the HLA region. Finally, neighbor joining tree analyses demonstrate the power of haplotype diversity for inferring the relationships between the different populations.

Alleles↗
PubMed2001

Prevalence and intensity of urinary schistosomiasis in primary school children of the Kotto Barombi Health Area, Cameroon.

OBJECTIVE: To assess the prevalence and intensity of urinary schistosomiasis in school pupils aged five to sixteen years. SETTING: Barombi Kotto Health Area, southwest Cameroon. DESIGN: A cross-sectional study. SUBJECTS: Three hundred and forty seven primary school children. INTERVENTION: All children found to be infected were treated with praziquantel (biltricide). MAIN OUTCOME MEASURES: The study would be able to provide baseline information on the epidemiology of schistosomiasis which is vital for control strategies. RESULTS: The overall prevalence of Schistosoma haematobium in the study areas was 53.6%, with the highest prevalence of 73.9% recorded in Barombi Kotto village. Children resident on Barombi Kotto island were more significantly infected than those on the peripheral mainland (93.3% versus 46.2%, p < 0.01). Prevalence rate and intensity of infection did not vary significantly (p > 0.05) with sex, class or age of the pupils. The mean egg count varied significantly between schools (p < 0.001). CONCLUSION: Barombi Kotto village was identified as the focus of urinary schistosomiasis, with the highest recorded in children dwelling on the island, the surrounding lake being the main focus of transmission. Focal snail control as an adjunct of chemotherapy and intensive health education for the local population are strongly recommended as a means of reducing the high infection rate in the area.

Adolescent↗
PubMed2001

Reduced levels of chloroquine resistant Plasmodium falciparum in selected foci of the South West Province, Cameroon.

OBJECTIVES: To evaluate the state of chloroquine resistant malaria in the South West Province of Cameroon. To estimate the prevalence of different species of Plasmodium in the area. DESIGN: A cross sectional study. SETTING: South West Province of Cameroon. SUBJECTS: 326 febrile patients. MAIN OUTCOME MEASURES: Chloroquine resistance studies using the WHO seven-day standard in vivo test. Speciation of malaria by polymerase chain reaction. Prevalence of falciparum malaria by light microscopy of thick blood smears. RESULTS: Prevalence of chloroquine resistance ranged from 4.3 to 13.2%. A total of six cases showed RIII resistance, and three cases showed RII resistance. Plasmodium falciparum was the predominant species, 96.8% of those testing positive for P. falciparum, 6.3% of cases showed mixed infections of P. falciparum and P. malariae. P. ovale accounted for 3% of cases. CONCLUSION: P. falciparum resistance to chloroquine may not be on the increase compared to earlier reports from the South West Province. The results have important implications in treatment of malaria in view of the low cost of chloroquine.

Adolescent↗
PubMed2001

Antibiogram of Klebsiella pneumoniae isolates from Buea, Cameroon.

OBJECTIVE: To determine the antibiotic susceptibility of K. pneumoniae isolates from Buea, Cameroon. DESIGN: A prospective study of K. pneumoniae isolates from clinical samples of nosocomial origin. SETTING: A laboratory based investigative study at the Biotechnology Centres of the Universities of Buea and Yaounde 1, Cameroon, and three Buea based hospitals. K. pneumoniae isolates were obtained from sputum, wound swabs and urine and screened for their antibiogram using standard procedures. RESULTS: Results on the antibiogram showed seven distinct antibiotypes distinguished by different susceptibilities to aminoglycosides (Spectinomycin and Gentamicin), Chloramphenicol and Augmentin. All the isolates shared multi-resistance to Amoxicillin and Trimethoprim. However, the isolates showed marked susceptibilities to Norfloxacin (90.01%), Cefuroxime (95.45%) and Ciprofloxacin (86.36%). CONCLUSION: The study has revealed that K. pneumoniae isolates in the environment of Buea, Cameroon are multi-drug resistant. This finding is of clinical and epidemiological significance.

Cameroon↗
PubMed1998

Three new DP alleles identified in sub-Saharan Africa: DPB1*7401, DPA1*02013, and DPA1*0302.

HLA-DP genotyping of over 400 individuals from sub-Saharan Africa identified three new DP alleles: DPB1*7401, DPA1*02013, and DPA1*0302. DNA sequencing confirmed that DPB1*7401, found in one individual, is a novel combination of previously described sequence motifs in the six variable regions of DPB1. DPA1*02013, found in one individual, is identical to DPA1*02012 except for two silent substitutions, a T to C transition in codon 37, and an A to G transition in codon 38. DPA1*0302, identified in seven individuals, is identical to DPA1*0301 except for a C to T transition at the second position of codon 66. The identification of these novel alleles brings the total number of reported DPB1 alleles to 77 and DPA1 alleles to 11.

Africa South of the Sahara↗
PubMed1997

Evidence for increased hydroxylation of pyrrolidone amino acid residues in the cuticle of mature Onchocerca volvulus.

To determine whether morphologic changes are accompanied by variations in the biochemical and antigenic properties of the cuticle of Onchocerca volvulus during development, we isolated and compared the 2-mercaptoethanol soluble cuticular proteins and the insoluble cuticlin from the predominant life-cycle stages occurring in man. SDS-PAGE analysis, before and after digestion with collagenase from Achromobacter iophagus, revealed that the polypeptide composition of the 2-mercaptoethanol-solubilised extracts from adult males and nodular microfilariae are quite distinct and that these extracts contained predominantly collagen-like proteins. Demonstrated by immunoblotting with a hyper immune patient serum pool (n = 107), five strongly reactive antigens with apparent molecular weights of 126, 68, 43, 37 and 33 kDa were detected in the extracts from adult males, while at least eight prominent and several weakly reactive components were detected in the extracts from nodular microfilariae. The overall amino acid composition of the cuticular extracts from the various stages demonstrates that: (a) the cuticle of the adult male stage is rich in glycine, pyrrolidone amino acids, and acidic amino acids or their amides, (b) eggshells are particularly poor in proline but rich in serine residues (14.5%), (c) nodular microfilariae cuticular extracts are poor in proline but rich in valine (9.0%) and lysine (7.3%) and (d) hydroxyproline and hydroxylysine are present in the cuticle of adults but absent in the juvenile life-cycle stages (nodular microfilariae and eggs). This study firstly, indicates that the composition of the cuticle of O. volvulus may thus, be quite distinct from one parasite stage to another and secondly, that the maturation of the parasite in the human host may be accompanied by the extensive hydroxylation of prolyl residues and to a lesser extent of lysyl residues in the predominantly collagen-like cuticular proteins.

Amino Acids↗
PubMed1997

Localization of T and B cell stimulating domains of the immunodominant 33-kDa protein of Onchocerca volvulus (Ov33).

The localization of T and B cell epitopes on a well characterized 33-kDa protein of the filarial nematode Onchocerca volvulus (Ov33) was studied using peripheral blood mononuclear cells (PBMC) and sera from a total of 52 onchocerciasis patients with the generalized form of infection. A proportion of the PBMC samples proliferated in response to recombinant Ov33-GST fusion protein and to fusion free Ov33-6xHis. Proliferative responses of patient PBMC to seven truncated Ov33-6xHis polypeptides and to three synthetic peptides revealed at least one major and two minor T cell epitopes in the protein. The dominant T cell stimulating domain was localized between amino acids 113 and 143. ELISA studies with the Ov33-GST fusion protein revealed that patient sera contained Ov33-specific IgG1, IgG4, IgE, and IgM antibodies. Analysis of the IgG4 response with 10 truncated Ov33 polypeptides identified four B cell stimulating domains in the N-terminal, central, and C-terminal region of the molecule. The B cell domain recognized by the majority of sera was localized between amino acids 113 and 143. The data indicate that this region of the protein is the major T and B cell stimulating domain of Ov33 and might be relevant for vaccine development and for improved immunodiagnosis of onchocerciasis.

Adolescent↗
PubMed1997

In vitro production and characterization of excretory/secretory products of Onchocerca volvulus.

Onchocerca volvulus excretory/secretory products [ESP] free of host contaminants are often needed for immunologic and biochemical studies. Since prolonged in vitro survival of O. volvulus in culture requires the presence of human serum, as a supplement, it was necessary to investigate other culture medium supplements in which pure ESP could be generated. Thus heat-inactivated normal rabbit serum, fetal calf serum and the synthetic serum substitute Ultroser-G were tested for their abilities to sustain O. volvulus adult females and nodular microfilariae in vitro and their abilities to promote the synthesis and release of ESP. Using [35S]-methionine as the radioactive precursor, O. volvulus nodular microfilariae and adult females were shown to actively synthesize and release excretory/secretory proteins with increasing efficiency in human serum, rabbit serum, Ultroser-G and fetal calf serum. Analysis of the ESP by SDS-PAGE revealed that at least 30 polypeptides in the 7-174 kDa range were continuously released. About 14 of these components were immunogenic to the human host as shown by immunoprecipitation. Prominent antigenic polypeptides were those with relative molecular weights of 13, 16, 33, 68 and 170. Rabbit serum, fetal calf serum and Ultroser-G could therefore, conveniently replace human serum in cultures of O. volvulus nodular microfilariae and adult females.

Animals↗
PubMed1996

Three new DPB1 alleles identified in a Bantu-speaking population from central Cameroon.

HLA-DPB1 genotyping of 241 individuals from an African Bantu-speaking population in central Cameroon using sequence-specific oligonucleotide probes identified five individuals with novel probe hybridization patterns. DNA sequence analysis of the second exon of the DPB1 alleles from these five individuals identified three new alleles, *6001, *6101N, and *6201. DPB1*6001, found in two individuals, contains a single nucleotide change that results in a polar amino acid, asparagine, at residue 65; this position in the beta 1 domain is occupied by a nonpolar amino acid in all other reported DPB1 alleles. DPB1*6101N, found in one individual, contains a single base mutation that results in a premature termination codon at position 67. DPB1*6201, found in two individuals, is characterized by the apparent motif shuffling that has been hypothesized to be responsible for the majority of DPB1 sequence polymorphism. These new sequences shed additional light on the potential mechanisms by which allelic diversity is generated at the HLA-DPB1 locus.

Africa↗
PubMed1995

Prevalence of schistosomiasis and other intestinal helminth infections among senior primary school children in Makenene Sub-Division, Cameroon.

A study was carried out in four villages of Makenene Sub-Division some 85 km north-west of Yaounde, between November 1993 and March 1994 to assess the prevalence and intensity of schistosomes and other helminth infections among senior primary school pupils aged 9-16. An extensive questionnaire was used to collect sociodemographic information and information on water-related activities. The overall prevalence of S. mansoni infection was 228 (23.6%) while S. haematobium infection was practically non-existent 03 (< 1%). Infection rates with intestinal nematodes were very high, up to 98% in some villages. Prevalence rates of schistosomiasis varied significantly (P < 0.05) between villages with the highest (36.2%) recorded in Makenene. Infections with other parasite species encountered were significantly different (P < 0.01) while a marked association was observed between water contact activities and the distribution of S. mansoni infections. However, S. mansoni infection intensities were not significantly different (P > 0.05) between those with a history of previous infection and treatment and those without.

Adolescent↗
PubMed1994

Phosphoprotein patterns in Onchocerca volvulus developmental stages.

Living females and microfilariae of Onchocerca volvulus incubated in culture medium containing [32P]orthophosphate were observed to phosphorylate their proteins rapidly. Patterns of phosphoproteins in extracts from these labelled parasites were compared after two dimensional electrophoresis and autoradiography. Protein extracts from eggs, microfilariae and adult females of O. volvulus were phosphorylated in the presence of [gamma-32P]ATP, magnesium acetate, and added cyclic AMP-dependent protein kinase or the endogenous protein kinase present in the extracts. Patterns of phosphoproteins were compared after separation by single and two-dimensional gel electrophoresis followed by autoradiography. Common phosphopeptide bands were observed when phosphorylated extracts from adult females, microfilariae and eggs were compared. However, extracts from eggs displayed unique phosphorylated polypeptides of M(r) 30,000 and 34,000 that were absent from the extracts from microfilariae. Furthermore, two phosphorylated polypeptides of M(r) 47,000 and 76,000 were detected in extracts from microfilariae but not from eggs. These results indicate that O. volvulus parasites may phosphorylate different proteins at different stages of their development.

Animals↗
PubMed1993

Characterization of a recombinant T cell and B cell reactive polypeptide of Onchocerca volvulus.

To identify potentially protective Ag of the filarial nematode Onchocerca volvulus on the molecular level we screened a cDNA library of O. volvulus with a human serum raised against radiation-attenuated infective larvae of O. volvulus. A cDNA clone of 218 bp (OvL3-1) was selected for further studies. It was expressed in Escherichia coli and affinity purified recombinant polypeptide was tested for its ability to stimulate in vitro PBMC from African onchocerciasis patients and PBMC from chimpanzees experimentally infected with O. volvulus. An enhanced cell proliferation by PBMC was observed in many patients after stimulation with the recombinant OvL3-1 polypeptide. In addition, some patients' PBMC responded to OvL3-1 stimulation with enhanced IL-2 production. Infected chimpanzees also showed an increase in T cell proliferation. Onchocerciasis patients had variable levels of specific antibodies directed to the recombinant polypeptide when sera were tested by ELISA. A mAb directed against the recombinant protein located the native target Ag in the muscles of the adult worm. The molecular mass of native OvL3-1 was found to be 50 kDa on immunoblots. Polymerase chain reaction analysis of RNA from different life stages of the parasite showed that OvL3-1 is transcribed in all parasite stages within the mammalian host. A homologous gene is also present in other filarial parasites. The protein corresponding to OvL3-1, therefore, represents an immunogen present during the whole life-span of the parasite, and because of its B and T cell stimulatory properties, it may be a candidate for a protective Ag in human filariasis.

Adult↗
PubMed1992

Cell-mediated and monoclonal antibody-dependent killing of Onchocerca volvulus microfilariae.

To identify the target antigens implicated in the adherence and killing of microfilariae (mf) by leucocytes, we incubated nodular mf and leucocytes in the presence of anti-cuticular monoclonal antibodies (MOVs) and fresh serum. Leucocyte donors were patients with a mean age of 37 years (with 0-1 mf/snip), who had lived in the endemic village studied for at least 10 years. After 16-20 h of incubation, up to 74% of the mf could be seen with 10 or more cells adhering to them. By 36-40 h up to 54% of the mf had been killed by the leucocytes in the presence of a cocktail of monoclonal antibodies termed MOV GIV. The degree of killing in control experiments with the monoclonal antibody MOV 1 remained lower (P less than 0.05), ranging from 0.0 to 4.5% of mf with initial viability of 90-95%. Western blotting revealed MOV GIV prominent target antigens of 10.5, 18.0, 23.5 and 27 kDa in crude surface extracts of female O. volvulus. The detected antigens may play a role in host protection.

Adolescent↗
PubMed1992

A monoclonal antibody-based immunodiagnostic assay for onchocerciasis.

Five murine monoclonal antibodies raised against Onchocerca volvulus cuticular extracts and termed MOVs (1-4 and 6) were selected based on reactivity with O. volvulus cryosections, and non-reactivity with cryosections of human skin and/or nodular tissue. Two others MOVs 5 and 7 reacted with both. Using the peroxidase-anti- peroxidase (PAP) histochemical method, the target epitopes of MOV 1 were located in the cuticle's basal and cortical layers, those of MOV 2 in the cortical layer; whilst MOV 3-7 stained the basal layer. A sandwich ELISA was then developed. The trapping polyclonal antibody was raised in rabbits utilising the same antigens as for preparation of the MOVs. Once captured on microtiter plates, target antigens were identified by the sequential binding of a MOV, followed by a goat anti-mouse globulin/peroxidase or alkaline phosphatase conjugate that catalysed a colorimetric reaction in the presence of appropriate substrates. In this system, MOV 1 emerged as the most specific and potent reagent capable of recognizing antigens of Onchocerca sp. with a minimal detection limit of 78 ng per test. MOV 1, failed to react with extracts of Loa Loa, Ascaris lumbricoides and Ascaris suum in the test. The developed assay relied on the use of MOV 1, required only 1 ml of urine or 0.05 ml serum. About 97.8% of the 47 urines and 50% of the 20 sera from patients studied gave positive results. Only 1 (3%) of 32 control urines and up to 80% of the 10 control sera studied tested positive, suggesting urine as a better specimen source.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Identification of different radiolabelled antigens of the developmental stages of Onchocerca volvulus.

By using radioiodination methods which are thought to label preferentially the surface followed by SDS-PAGE and autoradiography, components of different developmental stages of O. volvulus have been identified. Between 2 and 10 polypeptide antigens were revealed on infective larvae (L3), females, males, eggs, nodular and skin microfilariae by using immunoblotting assays with human onchocerciasis sera. Antigen recognition did not vary with the density of skin microfilariae in the patients from whom the sera were obtained. Some of the antigens seemed to be stage specific; for example, antigens of 31 kDa which were detected only on skin microfilariae, or the 67.5 and 25 kDa components that occurred on the adult females, but were absent from adult males. Some of these antigens were also identified as glycoproteins. A 68 kDa glycoprotein was found in adult females, males and nodular microfilariae. Two glycoproteins of 74 and 45 kDa were found on egg shells, and a 18.5 kDa glycoprotein was recovered from L3. Type VI collagen was found with a specific antiserum on skin microfilariae, but not on eggs and females. Laminin was found on nodular mf. It is concluded that the changing antigenic profiles of the worm stages and the coating of these worms with connective tissue epitopes contribute to the evasion of host immunity.

Animals↗
PubMed1990

Novel Onchocerca volvulus filaricides from Carapa procera, Polyalthia suaveolens and Pachypodanthium staudtii.

Suitable drugs for the elimination of adult Onchocerca volvulus are still needed since ivermectin, the new microfilaricide, appears to be ineffective against this parasite stage. Herein we report on the identification of filaricides in three medicinal plants. The compounds carapolide A, mexicanolide-methylangolensate mixture from Carapa procera and oliverine from Polyalthia suaveolens or Pachypodanthium staudtii when tested at 10-100 micrograms.ml-1 were found to exhibit considerable microfilaricidal activity after 24 hours of incubation. Oliverine was found to be filaricidal when tested against adult female worms at 100 micrograms.ml-1. Preliminary toxicity studies in mice showed carapolide A and the mexicanolide-methylangolensate mixture to be relatively non-toxic, whereas, oliverine had a minimal lethal dose of 8 mg.Kg-1 of body weight. Based on the above results further pharmacologic studies are recommended to determine, the potential application of the active compounds on the treatment of onchocerciasis.

Animals↗