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2. A non-Hermitian PT-symmetric kicked top

Author

Mudute-Ndumbe, Steve and Graefe, Eva-Maria

Subjects
Quantum Physics, Mathematical Physics
Abstract

A non-Hermitian PT-symmetric version of the kicked top is introduced to study the interplay of quantum chaos with balanced loss and gain. The classical dynamics arising from the quantum dynamics of the angular momentum expectation values are derived. The presence of PT-symmetry can lead to stable mixed regular chaotic behaviour without sinks or sources for subcritical values of the gain-loss parameter. This is an example of what is known in classical dynamical systems as reversible dynamical systems. For large values of the kicking strength a strange attractor is observed that also persists if PT-symmetry is broken. The intensity dynamics of the classical map is found to provide the main structure for the Husimi distributions of the subspaces of the quantum system belonging to certain ranges of the imaginary parts of the quasienergies. Classical structures are identified in the quantum dynamics. Finally, the statistics of the eigenvalues of the quantum system are analysed and it is shown that if most of the eigenvalues are complex (which is the case already for fairly small non-Hermiticity parameters) the nearest-neighbour distances of the (unfolded) quasienergies follow a two-dimensional Posisson distribution when the classical dynamics is regular. In the chaotic regime, they are in line with recently identified universal complex level spacing distributions for non-Hermitian systems, with transpose symmetry $A^T= A$. It is demonstrated how breaking this symmetry (by introducing an extra term in the Hamiltonian) recovers the more familiar universality class for non-Hermitian systems given by the complex Ginibre ensemble. Both universality classes display cubic level repulsion. The PT-symmetry of the system does not seem to influence the complex level spacings. Similar behaviour is also observed for the spectrum of a PT-symmetric extension of the triadic Baker map., Comment: revised version, extended and corrected, 23 pages, 17 figures

Published
2019
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5. Random matrix ensembles for $PT$-symmetric systems

Author

Graefe, Eva-Maria, Mudute-Ndumbe, Steve, and Taylor, Matthew

Subjects
Mathematical Physics, Quantum Physics
Abstract

Recently much effort has been made towards the introduction of non-Hermitian random matrix models respecting $PT$-symmetry. Here we show that there is a one-to-one correspondence between complex $PT$-symmetric matrices and split-complex and split-quaternionic versions of Hermitian matrices. We introduce two new random matrix ensembles of (a) Gaussian split-complex Hermitian, and (b) Gaussian split-quaternionic Hermitian matrices, of arbitrary sizes. They are related to the split signature versions of the complex and the quaternionic numbers, respectively. We conjecture that these ensembles represent universality classes for $PT$-symmetric matrices. For the case of $2\times2$ matrices we derive analytic expressions for the joint probability distributions of the eigenvalues, the one-level densities and the level spacings in the case of real eigenvalues., Comment: 9 pages, 3 figures, typos corrected, small changes, accepted for publication in Journal of Physics A

Published
2015
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11. An evaluation of infant immunization in Africa: is a transformation in progress?/Vaccination des nourissons: evaluation des progres realises en Afrique/Evaluacion de la inmunizacion de los lactantes en Africa: ?esta cambiando la situacion?

Author

Arevshatian, L., Clements, C.J., Lwanga, S.K., Misore, A.O., Ndumbe, P., Seward, J.F., and Taylor, P.

Subjects
Company financing, Company business management, Immunization -- Evaluation, Immunization -- Demographic aspects, Immunization -- Finance, Children -- Health aspects, Children -- Research, Children -- Management
Abstract

Objective To assess the progress made towards meeting the goals of the African Regional Strategic Plan of the Expanded Programme on Immunization between 2001 and 2005. Methods We reviewed data from national infant immunization programmes in the 46 countries of WHO's African Region, reviewed the literature and analysed existing data sources. We carried out face-to-face and telephone interviews with relevant staff members at regional and subregional levels. Findings The African Region fell short of the target for 80% of countries to achieve at least 80% immunization coverage by 2005. However, diphtheria-tetanus-pertussis-3 coverage increased by 15%, from 54% in 2000 to 69% in 2004. As a result, we estimate that the number of nonimmunized children declined from 1.4 million in 2002 to 900 000 in 2004. In 2004, four of seven countries with endemic or re-established wild polio virus had coverage of 50% or less, and some neighbouring countries at high risk of importation did not meet the 80% vaccination target. Reported measles cases dropped from 520 000 in 2000 to 316 000 in 2005, and mortality was reduced by approximately 60% when compared to 1999 baseline levels. A network of measles and yellow fever laboratories had been established in 29 countries by July 2005. Conclusions Rates of immunization coverage are improving dramatically in the WHO African Region. The huge increases in spending on immunization and the related improvements in programme performance are linked predominantly to increases in donor funding. Resume Objectif Evaluer les progres enregistres entre 2001 et 2005 dans la realisation des objectifs du Plan regional strategique pour l'Afrique du Programme elargi de vaccination. Methodes Nous avons analyse les informations provenant des programmes de vaccination des nourissons de 46 pays de la Region africaine de l'OMS et celles tirees de la litterature et des sources de donnees existantes a ce sujet. Nous avons procede a des entretiens en face-a-face ou par telephone avec des responsables au niveau regional ou infraregional de ces programmes, pouvant etre utiles a l'etude. Resultats En 2005, 80 % des pays de la Region africaine de l'OMS n'avaient pas reussi a atteindre l'objectif en termes de couverture vaccinale fixe pour cette annee, a savoir 80 % au moins. Neanmoins, le taux de couverture par le vaccin antidiphterique-antitetanique-anticoquelucheux 3 (DTC3) est passe de 54 % en 2000 a 69 % en 2004, soit une augmentation de 15 %. Nous estimons par consequent que le nombre d'enfants non vaccines a baisse de 1,4 million en 2002 a 900 000 en 2004. Au cours de cette derniere annee, on a releve un taux de couverture par le DTC ne depassant pas 50 % dans quatre des sept pays d'endemie ou de resurgence du poliovirus sauvage et un taux de couverture n'atteignant pas l'objectif de 80 % dans certains pays voisins exposes a un risque eleve d'importation de ce virus. Le nombre des cas notifies de rougeole est tombe de 520 000 en 2000 a 316 000 en 2005 et la mortalite due a cette maladie a diminue de 60 % par rapport aux niveaux de reference de 1999. Un reseau de laboratoires a ete mis en place dans 29 pays pour la surveillance de la rougeole et de la fievre jaune. Conclusion Les taux de couverture vaccinale augmentent considerablement dans la Region africaine de l'OMS. La tres forte hausse des depenses consacrees a la vaccination et a l'amelioration des resultats programmatiques connexes est liee principalement a l'augmentation du financement par les donateurs. Resumen Objetivo Evaluar los progresos realizados para alcanzar las metas del Plan Estrategico de la Region de Africa del Programa Ampliado de Inmunizacion entre 2001 y 2005. Metodos Estudiamos los datos de los programas nacionales de inmunizacion de lactantes de los 46 paises de la Region de Africa de la OMS, y analizamos la bibliografia y las fuentes de datos existentes al respecto. Ademas, llevamos a cabo entrevistas personales y telefonicas con los funcionarios oportunos a nivel regional y subregional. Resultados La Region de Africa no alcanzo la meta de que un 80% de Ios paises garantizara una cobertura de inmunizacion de al menos un 80% para 2005. Sin embargo, la cobertura con la vacuna contra la difteria, el tetanos y la tos ferina (DTP3) aumento en un 15%, del 54% en 2000 al 69% en 2004. En consecuencia, estimamos que el numero de ninos no inmunizados disminuyo de 1,4 millones en 2002 a 900 000 en 2004. En ese ultimo ano, cuatro de siete paises con poliovirus salvaje endemico o reintroducido presentaban una cobertura del 50% o menos, y algunos paises vecinos con alto riesgo de importacion no Iograron la meta de vacunaci6n del 80%. Los casos de sarampion notificados cayeron de 520 000 en 2000 a 316 000 en 2005, y la mortalidad por esa causa se redujo aproximadamente en un 60% en comparacion con Ios niveles basales de 1999. En julio de 2005 se habia establecido una red de laboratorios para el sarampion y la fiebre amarilla en 29 paises. Conclusion Las tasas de cobertura inmunitaria estan mejorando extraordinariamente en la Region de Africa de la OMS. Los enormes incrementos del gasto en inmunizacion y las mejoras resultantes en la ejecucion de Ios programas se deben sobre todo al aumento de Ios fondos de donantes. [TEXT NOT REPRODUCIBLE IN ASCI.], Introduction Every year more than 10 million children in low- and middle-income countries die before they reach their fifth birthdays. Most die because they do not access effective interventions that [...]

Published
2007

23. Hemangiopericytome Meninge: Rapport clinico-pathologique d\'un cas

Author

Enow-Orock, G, Eyenga, V, Eyong, CA, Essame-Oyono, JL, Ndumbe, P, and Bosman, FT

Subjects
Hemangiopericytoma - meningeal- Cameroon
Abstract

Nous rapportons l\'observation d\'un hémangiopéricytome de localisation méningée (HPCM) chez une femme de 42 ans reçue à l\'Hôpital Général de Yaoundé, Cameroun. Cette tumeur est rare chez nous, et la localisation méningée exceptionnelle. Le diagnostic histologique est difficile, la tumeur étant souvent confondue à un méningiome. La patiente a été opérée et ensuite soumise à une radiothérapie. Elle se porte bien 6 mois après son traitement. Il est recommandé aux pathologistes d\'exclure un probable HPCM en cas de ‘méningiomes atypiques\' primaires, récidivants ou métastatiques. Etant donné le taux de récurrence élevé avec des métastases tardives, un suivi des patients traités de cette tumeur à long terme s\'avère important. Une surveillance à long terme est prévue.The authors report the case of a meningeal hemangiopericytoma (MHPC) in a 42-year-old woman seen at the General Hospital Yaoundé, Cameroon. This tumour is rare in our environment, and the meningeal location is even rarer, difficult to diagnose histologically and often confused with a meningioma. The patient, who was treated by surgery followed by radiotherapy, is well six months after treatment. Pathologists are advised to rule out an MHPC in case of a primary, recurrent or metastatic ‘atypical meningioma\'. Given the high recurrent rate with late metastasis of this tumour, long term follow up of patients is important. A long term surveillance and follow-up is envisaged Keywords: Hemangiopericytoma - meningeal- Cameroon.Clinics in Mother and Child Health Vol. 5 (2) 2008: pp. 937-940

Published
2009

24. An assessment of interactions between global health initiatives and country health systems

Author

Samb, B., Evans, T., Dybul, M., Atun, R., Moatti, Jp, Nishtar, S., Wright, A., Celletti, F., Hsu, J., Kim, Jy, Brugha, R., Russell, A., Etienne, C., De, S, Mwase, T., Wang, Wj, Wright, J., Dare, L., Delfraissy, Jf, Boillot, F., Miege, P., Zhang, Xl, Rhatigan, J., Weintraub, R., Pun, S., Abe, C., Caceres, C., Camara, M., Coriat, B., D Almeida, C., Aleshkina, J., Murzalieva, G., Kadzandira, J., Hammami, N., Mwapasa, V., Chkhatarashvili, K., Buch, E., Miti, K., Kamenga, C., Elouma, Mse, Schwalbe, N., Greenberg, A., Frehywot, S., Markus, A., Goeman, L., Khan, A., Amati, J., Mwaura-Muiru, E., Ivers, Lc, Ellner, A., Shakow, A., Kley, Nc, Irwin, A., Sullivan, E., Baker, B., Cohn, J., Davis, P., Headley, J., Siplon, P., Dickinson, C., Pearson, M., Waddington, C., Boyer, S., Eboko, F., Orsi, F., Larouze, B., Le Loup, G., Ndubani, P., Simbaya, J., Boelaert, M., Cavalli, A., Ooms, G., Pirard, M., Polman, K., Damme, W., Dormael, M., Vermeiren, P., Teokul, W., Dlodlo, R., Fujiwara, P., Ruppol, S., Vella, S., Semigina, T., Corbett, E., Godfrey-Faussett, P., Spicer, N., Walt, G., Kanchanachitra, C., Philips, M., Riva, G., Kabuayi, Jp, Kiputsu, Ak, Ndongosieme, A., Koulla-Shiro, S., Samake, S., Bamba, Si, Coulibaly, Y., Traore, Mn, Berthe, Ibi, Wibulpolprasert, S., Chunharas, S., Jerome, G., Mukherjee, J., Nguini, Meo, Rao, Kd, Reddy, S., Nyirenda, L., Biesma, R., Bruen, C., Dicker, P., Walsh, A., Parsons, A., Mathole, T., Sanders, D., Raghavan, Ss, Mwanza, F., Michael, Eb, Richard, W., Banati, P., Blakley, M., Ingenkamp, N., Lansang, Ma, Low-Beer, D., Shakarishvili, G., Kayongo, A., Buse, K., Martineau, T., Dehne, K., Pett, I., Salama, P., Chilundo, B., Ndumbe, P., Atashili, J., Sow, Ps, Peter Hill, Brenzel, L., Babaley, M., Dayrit, M., Zoysa, I., Dyrhauge, J., Galichet, B., Kadama, P., Porignon, D., Russell, S., Tata, H., and Lerberghe, W.

Abstract

Since 2000, the emergence of several large disease-specific global health initiatives (GHIs) has changed the way in which international donors provide assistance for public health. Some critics have claimed that these initiatives burden health systems that are already fragile in countries with few resources, whereas others have asserted that weak health systems prevent progress in meeting disease-specific targets. So far, most of the evidence for this debate has been provided by speculation and anecdotes. We use a review and analysis of existing data, and 15 new studies that were submitted to WHO for the purpose of writing this Report to describe the complex nature of the interplay between country health systems and GHIs. We suggest that this Report provides the most detailed compilation of published and emerging evidence so far, and provides a basis for identification of the ways in which GHIs and health systems can interact to mutually reinforce their effects. On the basis of the findings, we make some general recommendations and identify a series of action points for international partners, governments, and other stakeholders that will help ensure that investments in GHIs and country health systems can fulfil their potential to produce comprehensive and lasting results in disease-specific work, and advance the general public health agenda. The target date for achievement of the health-related Millennium Development Goals is drawing close, and the economic downturn threatens to undermine the improvements in health outcomes that have been achieved in the past few years. If adjustments to the interactions between GHIs and country health systems will improve efficiency, equity value for money, and outcomes in global public health, then these opportunities should not be missed.

Published
2009

25. Antimicrobial activity against gram negative bacilli from Yaounde Central Hospital, Cameroon

Author

Gangoue-Pieboji, J, Koulla-Shiro, S, Ngassam, P, Adiogo, D, and Ndumbe, P

Subjects
antimicrobial agents, resistance, Gram-negative bacilli, bacteria susceptibility testing, Cameroon
Abstract

Background: Antimicrobial resistance among bacteria pathogens is a world-wide issue. The antimicrobial susceptibility patterns of common pathogenic bacteria are essential to guide empirical and pathogen-specific therapy; unfortunately, these data are scarse in Cameroon. Objective: To determine the antimicrobial susceptibility patterns of Gram-negative bacilli isolated in Yaounde Central Hospital Laboratory of Bacteriology. Methods: Gram-negative bacilli isolates (n = 505), obtained from a wide range of clinical specimens (urine, pus and blood) in Yaoundé Central Hospital Laboratory of Bacteriology between March 1995 and April 1998, were evaluated for resistance to antibiotics (amoxicillin, amoxicillin/clavulanate, piperacillin, cefazolin, cefoxitin, cefotaxime, ceftazidime, aztreonam, imipenem, gentamicin, tobramicin, ofloxacin and trimethoprim/sulfamethoxazole) by the Kirby-Bauer disk diffusion method. Results: High rates of resistance were found in most of the bacteria studied. Resistance to all isolates was mostly observed for amoxicillin (87%), piperacillin (74%) and trimethoprim/sulfamethoxazole (73%). Susceptibilities to third generation cephalosporins (cefotaxime, ceftazidime) and monobactame (aztreonam) were = 91% for Escherichia coli, = 71% for Klebsiella spp., = 98% for Proteus mirabilis, = 50% for Enterobacter spp. and Citrobacter spp. Pseudomonas aeruginosa was less susceptible to cefotaxime (2%) and aztreonam (33%), and highly susceptible to ceftazidime (72%) whereas Acinetobacter baumannii was highly resistant to aztreonam (100%), to cefotaxime (96%) and cetazidime (62%). Imipenem (98%) was the most active antibiotic followed by the ofloxacine (88%). Susceptibility of all isolates to gentamicin was 67%. Conclusion: These results indicate that surveillance to antimicrobial resistance in Cameroon is necessary to monitor microbial trends, antimicrobial resistance pattern, and provide information for choosing empirical or direct therapy to physicians. Keywords: antimicrobial agents, resistance, Gram-negative bacilli, bacteria susceptibility testing, Cameroon.> African Health Sciences Vol. 6 (4) 2006: pp. 232-235

Published
2007

26. From trees to money: the contribution of njansang (Ricinodendron heudelotii) products to value chain stakeholders’ financial assets in the South West Region of Cameroon

Author

Ndumbe, Louis Njie, Ingram, Verina, Tchamba, Martin, and Nya, Smith

Abstract

ABSTRACTNjansang -Ricinodendron heudelotii(Baill.) Pierre ex Pax.- is a commonly traded non-timber forest product from Central African humid forests, used as a spice. South West Cameroon was selected as major production area and market where little data exist on the contribution of njansang to stakeholders livelihoods in the value chain. Interviews were used to gather information from 261 harvesters, traders and processing enterprises. From 2013 to 2015, 65.8 tons were harvested, with 13.17 tons traded in markets in the South West Region and in Nigeria for a value of €33,511. The ease of accessing markets makes a significant difference to the quantity harvested and contribution to harvesters’ household income. Average profit for harvesters is higher in regional markets than in local ones. Harvester’s profits were higher than buy’amsell’ams, retailers and exporters. Processors add the most value and earn the highest unit profits. Livelihood dependence upon njansang decreases along the chain, with harvesters more dependent than traders. Seasonality, corruption, storage and processing, influence price. Long-term value chain sustainability could be improved by increasing collaboration between stakeholders, collective action, disseminating knowledge about processing and storage techniques, and promoting domestication and cultivation to enable trade in this largely wild harvested NTFP to continue sustainably.

Published
2019
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27. Blockchain for Strengthening the Privacy of Healthcare Data

Author

Kendzierskyj, Stefan, Jahankhani, Hamid, and Ndumbe, SHU

Abstract

The desire for eHealth systems is ever-growing as public institutions, healthcare providers, and its users see the positive gains from having systems of patient health information held in a single place; a decentralized connected architecture called blockchain. This concept can solve the interoperability issues and integrate the fragmented way healthcare records are held and present a more transparent, secure method to share data and protect patient privacy. The aim of this article is to provide a supportive environment for the health and social care workplace with special reference in the Primary Care sector in England on the impact and changes to the information governance toolkit (IGTK) as a result of the new European General Data Protection Regulation (GDPR) coming into force from May 2018. These challenges will also include the implementation of the National Data Guardian (NDG) review of data security and opt-outs amongst others.

Published
2019
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28. Extended-spectrum beta-lactamases (ESBLs) from various Enterobacteriaceae isolated at Yaounde Central Hospital (YCH), Cameroon

Author

Gangue-Pieboi, Joseph, Bedenić, Branka, Koulla-Shiro, S., Randegger, Corinne, Ndumbe, P., Adiogo, D., Ngasami, P., and Haechler, H.

Subjects
polycyclic compounds, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, extended-spectrum beta-lactamases, Enterobacteriaceae, ceftazidime, microbial resistance
Abstract

In a recent study, 14 Klebsiella pneumoniae (kp), 11 Escherichia coli ((Eco), 3 Citrobacter freundii (Cfr) and 1 Enterobacter cloacae (Ecl) strains isolated from patients in YCH, were found to be resistant to oxymino-cephalosporins (CAZ-ceftazidime, CTX-cefotaxime, CRO-ceftriaxone) and/or monobactam aztreonam (ATM) by standard disk-diffusion testing. There was a synergy between amoxycillin-clavulanate (AMC) and CAZ, CTX, CRO and ATM suggesting the presence of ESBL. Oxymino-cephalosporin and monobactam resistance was transferred to E. coli recipient (Eco HK 225) by conjugation (frequency of transfer: 2x10^-4 per input donor). Twelve of 29 strains were studied, and 6 Kp, 4 Eco, 1 Cfr and 1 Ecl were shown to possess a conjugative plasmid. Resistance determinants against the following non β -lactam antibiotics were co-transferred to Eco HK 225: (i) Gentamicin (Gm) (5 cases), and Trimethoprim/sulphametozaloe (3 cases). In contrast, resistance to cefoxitin (FOX) was not transferred. Crude extracts of ESBLs obtained by sonication of the transconjugants did not affect the inhibition zones of Eco HK 225 around FOX, AMC and imipenem disks. They did, however, inhibit the activities of amoxycillin, piperacillin, cefazolin, FOX, CRO, CTX, CAZ, and ATM. PCR was performed using plasmid DNA from transonjugants as template, and primers specific for blaSHV and blaTEM genes, respectively. The amplification products were sequenced directly . The deduced amino-acid sequence analysis according to the scheme of Ambler showed: (i) that eleven of twelve enzymes carried substitutions relative to SHV-1 at amino-acid position 35, 238 and 240 indicating SHV-12, and (ii) silent mutations at codons 222 and 268 that are of epidemiological interest. SHV-12 is the most prevalent ESBL at our hospital. The dissemination of this ESBL among various species could be due to 2 or 3 plasmids, which carry blaSHV-12 among other resistance genes, since our transconjugants have different resistance profiles. This is the first description of SHV-12 β -lactamase in Cameroon.

Published
2000

29. Trends of AIDS epidemic in Cameroon, 1986 through 1995

Author

John N. Nkengasong, Philippe Mauclère, Leopold Zekeng, Tapko Jb, Mbopi Kéou Fx, Laurent Bélec, Salla R, Affana G, Ndumbe P, Dora Mbanya, E. Mpoudi-Ngolle, Lazare Kaptue, and Monny Lobe M

Subjects
Adult, Male, Adolescent, Immunology, MEDLINE, Disease Outbreaks, Infectious Epidemiology, Acquired immunodeficiency syndrome (AIDS), Pregnancy, Virology, Environmental health, Prevalence, Immunology and Allergy, Medicine, Humans, Cameroon, Pregnancy Complications, Infectious, Child, Aged, Acquired Immunodeficiency Syndrome, business.industry, Infant, Newborn, Infant, Middle Aged, medicine.disease, Child, Preschool, HIV-2, HIV-1, Female, business
Published
1998

32. Evaluation of different V3 peptides in an enzyme immunoassay for specific HIV type 1 group 0 antibody detection

Author

Ondoa, P., Willems, B., Fransen, K., Nkengasong, J., Janssens, W., Heyndrickx, L., Zekeng, L., Ndumbe, P., Simon, F., Saragosti, S., Gürtler, L., Peeters, Martine, Korber, B., Goudsmit, J., and Van der Groen, G.

Subjects
EPIDEMIOLOGIE, DIAGNOSTIC, TEST, SIDA, VIRUS, IMMUNOLOGIE, VIH-1 GROUPE O, ANTICORPS
Abstract

Strategies to discriminate group O from group M infections need to be improved. We have developed and evaluated an HIV-1 group O V3 peptide-based enzyme immunoassay (PEIA) for specific HIV-1 group O antibody detection among HIV-1-infected patients. Synthetic peptides, derived from the amino acid sequences of the V3 loop of 15 different group O strains and 7 group O consensus sequences, were evaluated in a PEIA against a panel of genetically confirmed group O (n=33), group M (n=90), and HIV-1 antibody-negative sera (n=17). The best-performing PEIA(s) were then used to screen 134 sera of European and 336 sera of Cameroonian origin for the presence of anti-HIV-1 group O antibodies. The reactivity of reference ("gold standard") sera to individual peptides in the PEIA resulted in the selection of five different peptides with sensitivities (sens), specificities (spec), and test efficiencies (TEs) in the range of 90 to 100%. Improvement of the PEIA was obtained with simultaneous reactivity of at least two different peptides in separate wells of an ELISA plate, together with stringent criteria for positivity. We were able to select seven peptide combinations each with a sens, spec, and TE of 96.9, 100, and 99.2%, respectively. None of the 134 European and 4 (1.2%) of the 336 Cameroonian samples sera were group O positive in the optimized HIV-1 group O PEIA ; this was confirmed by the repeated presence of reactives, in agreement with the present knowledge of group O infection distribution. Finally, we were able to develop a strategy with a higher TE (99.2%) than the previously used ANT-70 (98.5%) and ANT-70/MVP5180 (95.7%). Our results show that optimal specificity rather than optimal sensitivity makes the V3 PEIA a sufficiently accurate epidemiological tool to be useful in estimating specifically group O infection among HIV-1-infected patients. (Résumé d'auteur)

Published
1998

34. Genetic and phylogenetic analysis of env subtypes G and H in Central Africa

Author

Janssens, W., Heyndrickx, L., Fransen, K., Motte, J., Peeters, M., Nkengasong, J. N., Ndumbe, P. M., Delaporte, E., Perret, J. L., Atende, C., Piot, P., and van der Groen, G.

Subjects
Subtypes, SIDA, PEPTIDE V3, Phylogenetics, Congo-Brazzaville, Congo-Kinshasa, Virology, HIV-1, Genetics, VIRUS, Africa, Central, PHYLOGENIE, Gabon, ANALYSE GENETIQUE
Published
1994

37. Large scale HIV survey in Cameroon by mass HIV testing mobile units: Evidence of HIV epidemic hot spot areas and high HIV vulnerability of women over time

Author

Mbopi-Keou, F.-X., primary, Kalla, G.C.M., additional, Guiadem, R., additional, Tchouamani, H., additional, Mbele, R., additional, Nkada, C., additional, Voundi, E., additional, Andze, G. Ondobo, additional, Takoungang, I., additional, Bélec, L., additional, Ndumbe, P., additional, and Angwafo, F., additional

Published
2010
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39. CAMEROON.

Author

Eyoh, Hansel Ndumbe, Butake, Bole, Doho, Gilbert, Kilo, Asheri, and Polycarpe, Oyi-Ndzie

Abstract

The article focuses on the history of performing arts in Cameroon. Under the administration of dictator Ahmadou Ahidjo, censorship in all cultural matters was extensive and draconian laws were approved to enforce them. The plays castigated not only colonialism but also its Cameroonian equivalents. Public performances were subjected to administrative authorizations. As a result, plays of pure indictment and more direct statement were rarely presented on stage.

Published
2001

40. OF INNER ROOTS AND EXTERNAL ADJUNCTS.

Author

Diakhaté, Ousmane and Eyoh, Hansel Ndumbe

Abstract

The article discusses the evolution of African theatrical art and the influences of western culture. Africans are thought to have their own personal forms of dramatic expression through rituals, dances, masquerades, storytelling, and folk celebrations. These traditions were interrupted by foreign invasion, first by Arabs, then by Europeans, which affected all aspects of the society. With the conquest of the continent in 1902 came to existence the terms francophone, anglophone and lusophone.

Published
2001

47. Drug Resistance Among Drug-naive and First-line Antiretroviral Treatment-failing Children in Cameroon

Author

Fokam, Joseph, Salpini, Romina, Santoro, Maria Mercedes, Cento, Valeria, Perno, Carlo-Federico, Colizzi, Vittorio, Ndumbe, Peter Martins, Fokunang Ntungen, Charles, Tetang, Suzie Moyo Ndiang, Nanfack, Aubin Joseph, Komego, Désiré Augustin Takou, and Cappelli, Giulia

Abstract

Scale-up to antiretroviral therapy (ART) requires surveillance for HIV drug resistance. With the goal of attaining 100 pediatric ART coverage in Cameroon, strategies to limit the spread of HIV resistance among children are very important.

Published
2011
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48. Differences in surface antigen expression of human fibroblasts cultured from bone marrow compared with those obtained from skin and embryon lung tissue.

Author

Ndumbe, P. M. and Levinsky, R. J.

Subjects
*LYMPHOBLASTIC leukemia, *IMMUNITY, *IMMUNOGLOBULINS, *KILLER cells, *T cells, *BONE marrow, *ANTIGENS, *IMMUNE system
Abstract

We have described the optimal conditions for the culture of human fibroblast cells from whole bone marrow aspirates and have shown that these fibroblasts differ in surface markers from those obtained from the skin and embryo lung tissue. All three fibroblast types express HLA class I antigens, together with an antigen found on T cells, granulocytes, white matter of brain and breast epithehal cells, but none of them expressed HLA class 2 antigens. In addition, skin fibroblasts expressed an antigen found on common acute lymphoblastic leukaemia cells, while bone marrow fibroblasts expressed an antigen found on human natural killer cells. Hence, all three types of fibroblasts can be separated on the basis of their surface markers, thereby suggesting a difference in maturation pathways. [ABSTRACT FROM AUTHOR]

Published
1985

49. Development and Application of a Broadly Sensitive Dried-Blood-Spot-Based Genotyping Assay for Global Surveillance of HIV-1 Drug Resistance

Author

Yang, Chunfu, McNulty, Amanda, Diallo, Karidia, Zhang, Jing, Titanji, Boghuma, Kassim, Sidibe, Wadonda-Kabondo, Nellie, Aberle-Grasse, John, Kibuka, Tabitha, Ndumbe, Peter M., Vedapuri, Shanmugam, Zhou, Zhiyong, Chilima, Benson, and Nkengasong, John N.

Abstract

ABSTRACTAs antiretroviral therapy (ART) is scaled up in resource-limited countries, surveillance for HIV drug resistance (DR) is vital to ensure sustained effectiveness of first-line ART. We have developed and applied a broadly sensitive dried-blood-spot (DBS)-based genotyping assay for surveillance of HIV-1 DR in international settings. In 2005 and 2006, 171 DBS samples were collected under field conditions from newly diagnosed HIV-1-infected individuals from Malawi (n= 58), Tanzania (n= 60), and China (n=53). In addition, 30 DBS and 40 plasma specimens collected from ART patients in China and Cameroon, respectively, were also tested. Of the 171 DBS analyzed at the protease and RT regions, 149 (87.1%) could be genotyped, including 49 (81.7%) from Tanzania, 47 (88.7%) from China, and 53 (91.4%) from Malawi. Among the 70 ART patient samples analyzed, 100% (30/30) of the Chinese DBS and 90% (36/40) of the Cameroonian plasma specimens were genotyped, including 8 samples with a viral load of <400 copies/ml. The results of phylogenetic analyses indicated that the subtype, circulating recombinant form (CRF), and unique recombinant form (URF) distribution was as follows: 73 strains were subtype C (34%), 37 were subtype B (17.2%), 24 each were CRF01_AE or CRF02_AG (11.2% each), 22 were subtype A1 (10.2%), and 9 were unclassifiable (UC) (4.2%). The remaining samples were minor strains comprised of 6 that were CRF07_BC (2.8%), 5 that were CRF10_CD (2.3%), 3 each that were URF_A1C and CRF08_BC (1.4%), 2 each that were G, URF_BC, and URF_D/UC (0.9%), and 1 each that were subtype F1, subtype F2, and URF_A1D (0.5%). Our results indicate that this broadly sensitive genotyping assay can be used to genotype DBS collected from areas with diverse HIV-1 group M subtypes and CRFs. Thus, the assay is likely to become a useful screening tool in the global resistance surveillance and monitoring of HIV-1 where multiple subtypes and CRFs are found.

Published
2010
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50. Prenatal Diagnosis in the First Trimester of Pregnancy

Author

Ndumbe, F M., Navti, O, Chilaka, V N., and Konje, J C.

Abstract

In the past 2 decades, the second trimester of pregnancy has been the most common time for prenatal diagnosis of fetal anomalies and chromosomal aneuploidies. More recently, screening for and diagnosis of chromosomal abnormalities are increasingly being performed in the first trimester. With improvements and technological advances in ultrasound, it is now possible to identify many fetal structural anomalies at 11 to 13 6/7 weeks' gestation. At 10 to 11 weeks' gestation, biochemical markers in serum—PAPP-A, free -hCG, AFP, and uE3—combined with sonographic measurement of nuchal translucency and the presence/absence of the nasal bone can achieve a Down syndrome detection rate of 97.5% at a false-positive rate of 5%. Structural anomalies of the central nervous system, and the cardiac, renal, and gastrointestinal tracts can now be diagnosed by either transabdominal or transvaginal scanning, achieving detection of up to 80% of CNS anomalies by 13 weeks' gestation. In future, the emphasis in prenatal diagnosis will likely be in the first trimester.

Published
2008
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