Deeper Insight in Metastatic Cancer progression;Epithelial-to-Mesenchymal Transition and Genomic Instability: implications on treatment resistance

Therapy resistance remains the major obstacle to successful cancer treatment. Epithelial-to- mesenchymal transition [EMT], a cellular reprogramming process involved in embryogenesis and organ development and regulated by a number of transcriptional factors [EMT-TFs] such as ZEB1/2, is recognized for its role in tumor progression and metastasis. Recently, a growing body of evidence has implicated EMT in cancer therapy resistance but the actual mechanism that underlie this finding has remained elusive. For example, whether it is, the EMT states in itself or the EMT-TFs that modulates chemo or radio-resistance in cancer is still contentious. Here, we summarise the molecular mechanisms of EMT program and chemotherapeutic resistance in cancer with specific reference to DNA damage response [DDR]. We provide an insight into the molecular interplay that exist between EMT program and DNA repair machinery in cancer and how this interaction influences therapeutic response. We review conflicting studies linking EMT and drug resistance via the DNA damage repair axis. We draw scientific evidence demonstrating how several molecular signalling, including EMT-TFs work in operational harmony to induce EMT and confer stemness properties on the EMT-susceptible cells. We highlight the role of enhanced DNA damage repair system associated with EMT-derived stem cell-like states in promoting therapy resistance and suggest a multi-targeting modality in combating cancer treatment resistance.

Hepatitis B virus precore/core region mutations and genotypes among hepatitis B virus chronic carriers in South-Eastern, Nigeria

OBJECTIVES

The study aimed at detecting the prevailing hepatitis B virus (HBV) genotypes and the presence of clinically relevant mutations in the precore/core gene of the HBV DNA, among patients with chronic infection in South-eastern, Nigeria.

METHODS

A total of 72 participants with chronic HBV infection were enrolled into the study. Plasma samples from those with detectable HBV DNA were subjected to nested Polymerase Chain Reaction amplification using the precore/core specific primers. This resulted to the successful amplification and sequencing of the HBV precore/core region DNA from 16 participants. Mutation analysis on the precore/core region detected the presence of certain HBV precore/core gene mutations. Genotyping was carried out by phylogenetic analysis.

RESULTS

The precore region mutation at nucleotide position 1896, which is a G to A change resulting to a nonsense mutation, was detected in 6.25% of the participants. Other HBV precore region mutations that were detected include: G1899A, T1846A, G1862C, G1888A, T1821C, C1826T, A1827C, A1850T, C1858T, precore start codon Kozak sequence mutations and some novel core region mutations such as G/A1951T and G1957A. Genotyping revealed the existence of HBV genotype/subgenotype A1 (87.5%) and D (12.5%) among the participants. There was no significant difference in the occurrence of specific precore/core mutations among the HBV/hepatitis C virus dually infected and HBV mono-infected participants.

CONCLUSION

The data suggest the likelihood of a more severe outcome of hepatitis caused by HBV in South-eastern Nigeria due to the occurrence of a variety of precore/core mutation, which resulted to HBeAg-negative chronic HBV infection among the participants.

Mycobacterium africanum and nontuberculous mycobacteria from fresh milk of pastoral cattle and soft cheese in Oyo State--implications for public health

BACKGROUND

Milk and.milk products from cattle in tuberculosis endemic countries like Nigeria where pasteurization is not enforced could be a source of health concerns to the consumers.

METHODS

We assessed randomly selected fresh milk from pastoral cattle, cheese samples and sour milk (nono) for the presence of Mycobacterium species through cultural isolation, Multiplex Polymerase Chain Reaction (PCR) and PCR-restriction enzyme analysis (PRA)-hsp65.

RESULTS

Out of 269 fresh milk, 295 cheese and 150 sour milk samples screened; 8.30%, 0.34% and 0.00%, respectively were positive for Mycobacterium species. Molecular characterization revealed three M. africanum (fresh milk = 2; cheese = 1) and a high prevalence of Non-tuberculous Mycobacterium (NTM; 89.29%) from fresh milk comprising M. gordonae (n = 12), M. fortuitum (n = 4), M. senegalense (n = 7) and M. avium (n = 1).

CONCLUSION

The isolation of M. africanum and NTM species from this study is a matter of public health concern considering the practice of pooling milk from different animals and the consumption of unpasteurized milk which characterize most pastoral communities in Nigeria. Given the predominance of NTM in this study, their potential to cause disease in humans should not be ignored. Urgent measures should also be taken to integrate molecular techniques that will differentiate NTM from members of the M. tuberculosis complex in the epidemiology of tuberculosis in order to avoid misdiagnosis in humans and thereby protect public health.

Molecular characterization of Mycobacterium bovis in slaughtered cattle in North-Central Nigeria and the public health implications

BACKGROUND

The molecular biological techniques of polymerase chain reaction (PCR) are accurate and rapid diagnostic methods in the epidemiology of Mycobacterium species in humans and animals, especially in developing countries.

METHODS

In this study, positive cultures from suspected tuberculous lesions of slaughtered cattle from two abattoirs in north-central Nigeria were subjected to a two-step multiplex PCR technique, based on genus typing and genomic regions of difference (RD).

RESULTS

Out of 50 suspected tuberculous lesions cultured, 40 isolates were obtained. Based on genus typing, 32 of the isolates were identified as Mycobacterium tuberculosis complex (MTC), one as non-tuberculous Mycobacterium (NTM) and the remaining seven were unclassified. Using genomic RD multiplex PCR, all the 32 isolates initially identified as MTC were further characterized as M. bovis.

CONCLUSION

Our findings show that 80% of positive cultures from suspected tuberculous lesions were identified as M. bovis; hence, re-confirming M. bovis as the main cause of bovine tuberculosis in Nigeria. These results give further credence to the use of PCR-based molecular techniques as excellent complementary epidemiological tools in the tracking of bovine tuberculosis, a zoonotic disease of major public health importance in Nigeria.

Genomic and proteomic analysis of Schizaphis graminum reveals cyclophilin proteins are involved in the transmission of cereal yellow dwarf virus

Yellow dwarf viruses cause the most economically important virus diseases of cereal crops worldwide and are transmitted by aphid vectors. The identification of aphid genes and proteins mediating virus transmission is critical to develop agriculturally sustainable virus management practices and to understand viral strategies for circulative movement in all insect vectors. Two cyclophilin B proteins, S28 and S29, were identified previously in populations of Schizaphisgraminum that differed in their ability to transmit the RPV strain of Cereal yellow dwarf virus (CYDV-RPV). The presence of S29 was correlated with F2 genotypes that were efficient virus transmitters. The present study revealed the two proteins were isoforms, and a single amino acid change distinguished S28 and S29. The distribution of the two alleles was determined in 12 F2 genotypes segregating for CYDV-RPV transmission capacity and in 11 genetically independent, field-collected S. graminum biotypes. Transmission efficiency for CYDV-RPV was determined in all genotypes and biotypes. The S29 isoform was present in all genotypes or biotypes that efficiently transmit CYDV-RPV and more specifically in genotypes that efficiently transport virus across the hindgut. We confirmed a direct interaction between CYDV-RPV and both S28 and S29 using purified virus and bacterially expressed, his-tagged S28 and S29 proteins. Importantly, S29 failed to interact with a closely related virus that is transported across the aphid midgut. We tested for in vivo interactions using an aphid-virus co-immunoprecipitation strategy coupled with a bottom-up LC-MS/MS analysis using a Q Exactive mass spectrometer. This analysis enabled us to identify a third cyclophilin protein, cyclophilin A, interacting directly or in complex with purified CYDV-RPV. Taken together, these data provide evidence that both cyclophilin A and B interact with CYDV-RPV, and these interactions may be important but not sufficient to mediate virus transport from the hindgut lumen into the hemocoel.

Antimicrobial effects of Piper guineense 'Uziza' and Phyllantus amarus 'Ebe-benizo' on Candida albicans and Streptococcus faecalis

Two pathogens were employed, Streptococcus faecalis and Candida albicans for the study of the antimicrobial effects of Piper guineense and Phyllantus amarus using agar-well diffusion and disc-diffusion methods. Phytochemical screening of ethanol, cold and hot water extracts detected the presence of tannins, saponins, flavonoids, terpenoids and phlobatannins. Antimicrobial effect of the plant extracts showed that the organic solvent and aqueous solvents of P. amarus were inhibitory to S. faecalis while the extracts of Phyllantus amarus were not inhibitory to Candida albicans. Agar-well determined Minimum Inhibitory Concentration (MIC) values ranged between 3.125 mg/ml and 6.25 mg/ml while the disc diffusion determined MIC values ranged between 6.25 mg/ml and 25.0 mg/ml. The agar-well determined MIC values for the ethanolic P. amarus extracts (3.12 mg/ml) were lower than the corresponding disc-diffusion MIC determined values (6.25 mg/ml-25.00 mg/ml). Bacteriocidal and bacteriostatic effect varied with, solvent type of extract, concentration of the plant extract and the method of the test adopted. The active components of the plant have no antifungal effect on the tested yeast (Candida albicans). These findings are discussed in relation to plant chemicals as a means of disease control and also to the problem of microbial resistance to synthetic drugs.

Band erosion: incidence, etiology, management and outcome after banded vertical gastric bypass

BACKGROUND

Prosthetic devices have been used in bariatric operations to control the outlet of the gastric pouch and thus maintain weight loss. A complication of these prostheses is erosion or migration into the gastric lumen. The transected banded vertical gastric bypass (TBVGBP) is one of the modifications of gastric bypass. This modification has a silastic ring placed around the pouch to form the stoma.

METHOD

The records of patients with band erosion (BE) after this operation were reviewed, to determine the incidence, etiology, management and outcome during a 9-year period.

RESULTS

From May 1992 through May 2001, 2,949 primary and secondary TBVGBP were performed through the Center for Surgical Treatment of Obesity, utilizing 3 hospitals. 48 patients (1.63%) were documented to have BE: 40 documented by us and 8 by subsequent treating surgeons or at other facilities. Presenting symptoms were weight regain (18), stenosis or obstruction (17), pain (9), bleeding (7), and 5 were incidental findings. Some patients presented with more than one symptom. 8 were treated expectantly with spontaneous extrusion of the band. 16 bands have been removed endoscopically in 14 patients. 26 patients had open surgical revision, with 12 having band removal only and 14 band removal and revision of either the gastroenterostomy with or without band replacement or conversion to a distal Roux-en-Y gastric bypass (DRYGBP). Two patients who had revision to DRYGBP were re-revised to a longer common limb because of protein malnutrition. Three patients who had revision of the gastroenterostomy with band removal and replacement developed leaks that were managed non-surgically. Two of these re-eroded and the band was removed endoscopically with a subsequent revision to a DRYGBP. There was no death due to BE.

CONCLUSION

BE is an uncommon complication of TBVGBP. Infection, previous bariatric operations and surgical technique play a role in BE. BE is best managed by endoscopic removal but can be treated expectantly or by open surgical intervention. Band removal without replacement or revision to DRYGBP may result in weight regain.

Prospective comparative evaluation of stapled versus transected silastic ring gastric bypass: 6-year follow-up

BACKGROUND

The effect of transecting vs. stapling the stomach in continuity in the banded gastric bypass (GBP) operation was studied.

METHOD

50 patients, 25 in each group, were enrolled into a prospective study to determine if transecting the stomach vs. stapling it in continuity in performing GBP for obesity decreases the incidence of gastro-gastric fistula formation without increased morbidity.

RESULTS

The patient profiles in the 2 groups were very similar. The peri-operative complications included 1 splenic capsular injury in each group, controlled without a splenectomy. There was 1 anastomotic leak in the stapled and 1 bleeding from the cut edge of the bypassed stomach in the transected group, both requiring re-operations in the immediate postoperative period. There was no peri-operative mortality. The percent follow-up after 6 years was 80% and 88% in the stapled and transected groups respectively. The incidence of late complications of solid food intolerance, ventral incisional hernia, cholelithiasis and small bowel obstruction was similar in both groups. There were 8 gastro-gastric fistulas in the stapled group and 1 in the transected group. The reduction in body mass index and percent excess weight loss (66%) were similar in both groups.

CONCLUSION

The incidence of gastro-gastric fistula may be reduced in GBP procedures by transecting the stomach as opposed to stapling it in continuity, without an increase in morbidity or mortality or any loss in the effectiveness of the operation.

Revision of Failed Gastric Bypass to Distal Roux-en-Y Gastric Bypass: A Review of 65 Cases

BACKGROUND

No bariatric operation has been documented to effect adequate weight loss in all patients. Patients with inadequate weight loss or significant weight regain with an anatomically intact short-limb gastric bypass, of which the Fobi pouch operation (FPO) for obesity is a modification, are usually revised to a distal Roux-en-Y gastric bypass (DRYGBP) to enhance weight loss.

METHOD

A retrospective review of the charts of all patients who had a revision to a DRYGBP at our Center during an 8-year period was carried out and the findings analyzed.

RESULTS

65 patients who had the FPO had a revision to the DRYGBP. Most were super obese patients who, even though they had lost significant weight, were still morbidly obese. Some were patients who had not lost adequate weight or <40% excess weight, and a small number were patients who requested more weight loss even though they had a BMI of < 35. 15 patients developed protein malnutrition requiring supplemental feeding. 6 required rerevision to short-limb gastric bypass.

CONCLUSION

Revision of short-limb gastric bypass to DRYGBP usually enhances weight loss but at a cost of an increased incidence of protein malnutrition.

Panniculectomy adjuvant to obesity surgery

BACKGROUND

Many patients who qualify for obesity surgery have a moderate to large panniculus (grade 1-5). They can benefit from panniculectomy done concurrently with gastric bypass (GBP) or subsequently after significant weight reduction, usually 18 months after the GBP.

METHOD

Over the last 8 years, 2,231 bariatric operations were performed at the Center. 577 panniculectomies were done, with 428 (74.2%) concurrent with the GBP and 149 (25.8%) subsequent to the GBP.

RESULTS

The redundant pannus weighed from 5 to 54.5 kg. Wound problems occured in 15.1% of panniculectomies. Transfusion was necessary in 1.9%. Hospital stay was 4 to 5 days, and was no greater than in patients that underwent the GBP alone. Those with grades 3-5 suffer more back-pain and problems of hygiene resulting from panniculitis.

CONCLUSION

A very redundant panniculus compounds the patient's physical, social and emotional problems. Where cardiopulmonary and other medical status are satisfactory, a panniculectomy may be offered to patients with a symptomatic panniculus at the time of bariatric surgery, as a physically beneficial and cost-effective adjuvant.