Search

Restriction sites introduced into the Bacillus Stearothermophilus lactate dehydrogenase gene enabled a region of the gene, coded for a mobile surface polypeptide loop acting as a sealant for the active site vacuole and determining substrate specificity, to be excised. A polymerase chain reaction and oligonucleotide extension was used to obtain double-stranded DNA regions coded for different length and sequence loops and containing the same restriction sites. These loops were then inserted into the cut gene and used to synthesize hydroxyacid dehydrogenases with altered substrate specificities. Phenylpyruvate activity was unaltered and a switch in specificity was achieved.

Abstract Background Knowledge of the distribution of human papillomavirus (HPV) genotypes among women with cervical lesion and in invasive cervical cancer is crucial to guide the introduction of prophylactic vaccines. There is no published data concerning HPV and cervical abnormalities in Sudan. This study aimed to define the prevalence of HPV and its subtypes in the cervical smears of women presenting with gynecological complains at Omdurman Military Hospital, Sudan. During the period between March 2003 and April 2004, 135 cervical smears collected from these women, were screened using cytological techniques, and analysed by PCR for (beta)-globin and HPV DNA using gel electrophoresis and ELISA. Results Of these 135 smears, there were 94 (69.3%) negative, 22 (16.3%) positive for inflammation, 12(8.9) mild dyskaryosis, 5 (3.7) moderate dyskaryosis and 2 (1.8) severe dyskaryosis. There were 60.7% ß. globin positive samples for HPV indicating DNA integrity. HPV DNA was identified in three samples (2.2%) by gel electrophoresis and. was positive in four samples (2.9%) as single and multiple infections by PCR-ELISA. The high risk HPV types 16 and 58 were identified in one sample as a mixed infection. The low risk HPV types 40 and 42 were also found as a mixed infection in another patient. HPV types 58 and 42 were identified in the other two patients. Conclusion HPV type distribution in Sudan appears to differ from that in other countries. The HPV genotypes identified were not associated with cancer.