Paucity of HPV-Related Head and Neck Cancers (HNC) in Nigeria

IntroductionThe burden of HPV-related Head and Neck Cancers (HNC) has been rising in the U.S. and other developed countries but this trend has not been reported in Africa. Objective of study was to evaluate the prevalence of HPV infection in HNC cancer cases seen between 1990 and 2011 at the tertiary health care institutions in Nigeria.MethodsWe retrieved 149 head and neck cancer formalin fixed, paraffin embedded tumor specimens diagnosed between 1990 and 2011 from four teaching hospitals in Nigeria. One hundred and twenty-three blocks (83%) contained appropriate HNC for analysis while DNA extraction was successful in 60% (90/149). PCR amplification was successful in 33% (49/149) and Linear Array genotyping for HPV was successful in 11% (17/149) of these cases. These were in tumors from the larynx (6), cervical lymph nodes (3), nasal cavity (2), parotid (1), palate (1), maxillary sinus (1) and mandible (1). Two cases were non-specific and none were from the oropharynx. Histologically, 41% (7/17) of the successfully genotyped blocks were squamous cell carcinomas (larynx 6, maxillary sinus 1).

Results and Conclusion

We were unable to detect HPV in any of the HNC samples in our study. Our result may suggest that there is a low prevalence of HPV-related HNC among the adult population in Nigeria. Our results provide a benchmark to compare future incidence of HPV -related HNC in this community in future. We had significant analytical challenges from possible poor tissue processing and urge that future studies should prospectively collect samples and ensure high quality sample processing.     

Microbial degradation of petroleum hydrocarbons in a polluted tropical stream

Summary Crude oil degradation was observed in water samples from three sites along the course of a polluted stream in Lagos, Nigeria. Consistent increase and decrease in the total viable counts (TVCs) of indigenous organisms occurred in the test and control experiments, respectively. Enrichments of the water samples with crude oil resulted in the isolation of nine bacteria belonging to seven genera. A mixed culture was developed from the assemblage of the nine species. The defined microbial consortium utilized a wide range of pure HCs including cycloalkane and aromatic HCs. Utilization of crude oil and petroleum cuts, i.e., kerosene and diesel resulted in an increase in TVC (till day 10) concomitant with decreases in pH and residual oil concentration. Crude oil, diesel and kerosene were degraded by 88, 85 and 78%, respectively, in 14 days. Substrate uptake studies with axenic cultures showed that growth was not sustainable on either cyclohexane or aromatics while degradation of the petroleum fractions fell below 67% in spite of extended incubation period (20 day). From the GC analysis of recovered oil, while reductions in peaks of n-alkane fractions and in biomarkers namely n-C₁₇/pristane and n-C₁₈/phytane ratios were observed in culture fluids of pure strains, complete removal of all the HC components of kerosene, diesel and crude oil including the isoprenoids was obtained with the consortium within 14 days.     

Comparative assessment of fermentation techniques useful in the processing of ogi

Ogiis processed traditionally by the use of uncontrolled spontaneous fermentation of maize, sorghum and millet. In this study, traditionally applied spontaneous fermentation was compared with accelerated batch fermentation (or back-slopping) and the use of starter cultures to initiate fermentation. Lactic acid bacteria populations comprised 95 of the total viable bacteria and remained prominent throughout the fermentations, while number of moulds and coliform bacteria declined as the fermentation progressed. The fermentation method involving the application of starter culture helps most to control the prevalence of coliforms and moulds. Lactic acid bacteria, such as Lactococcus raffinolactis, Pediococcussp.,Pediococcus pentosaceus, Lactobacillus plantarum, Lb. suebicus and Lb. brevis,were isolated at different processing stages of ogi using accelerated batch fermentation (back-slopping) technique. Highest increase in acidity was observed immediately after wet-milling and sieving fermenting maize grains at 28 and 48 h. Sharp increases in the reducing sugar levels were noted between 24 and 28 h of fermentations during wet-milling and sieving processes.     

Microbial assessment and quality evaluation of ogi during spoilage

The changes during the fermentation of ogi, a cereal-based traditional lactic acid-fermented weaning food were studied up to the spoilage stage. Ogi off-odour was first noticed at the fourth day of fermentation (including 24 h steeping). Yeast isolates such as Candida valida, C. krusei, Geotrichum candidum and bacteria like Lactobacillus brevis, L. plantarum, Pediococcus pentosaceus, Bacillus subtilis, Brevibacterium linens, Br. oxydans and other two Brevibacterium spp. dominated the fermenting mash at the spoilage stage. The brevibacteria contributed most significantly to ogi off-odour. Ogi samples inoculated with lactic acid bacteria increased acidity and product acceptability over the time of fermentation. The pH, titratable acidity, dissolved hydrogen sulphide and the presence of brevibacteria appear as good indices for monitoring spoilage. Hydrogen sulphide (H₂S) levels appear to be the most useful of the parameters studied. No coliforms and clostridia were identified during spoilage.     

Diversity of Predominant Lactic Acid Bacteria Associated with Cocoa Fermentation in Nigeria

The fermentation of cocoa relies on a complex succession of bacteria and filamentous fungi, all of which can have an impact on cocoa flavor. So far, few investigations have focused on the diversity of lactic acid bacteria involved in cocoa fermentation, and many earlier investigations did not rely on polyphasic taxonomical approaches, which take both phenotypic and genotypic characterization techniques into account. In our study, we characterized predominant lactic acid bacteria from cocoa fermentations in Nigeria, using a combination of phenotypic tests, repetitive extragenic palindromic PCR, and sequencing of the 16S rRNA gene of representative strains for accurate species identification. Thus, of a total of 193 lactic acid bacteria (LAB) strains isolated from common media used to cultivate LAB, 40 (20.7%) were heterofermentative and consisted of either L. brevis or L. fermentum strains. The majority of the isolates were homofermentative rods (110 strains; 57% of isolates) which were characterized as L. plantarum strains. The homofermentative cocci consisted predominantly of 35 (18.1% of isolates) Pediococcus acidilactici strains. Thus, the LAB populations derived from these media in this study were accurately described. This can contribute to the further assessment of the effect of common LAB strains on the flavor characteristics of fermenting cocoa in further studies.