Biomedical subjects

Richard Fox

Publications and source records attributed to Richard Fox.

4 recordsLinked to original sources

PubMed2003

Insertion of the T3 DNA polymerase thioredoxin binding domain enhances the processivity and fidelity of Taq DNA polymerase.

Insertion of the T3 DNA polymerase thioredoxin binding domain (TBD) into the distantly related thermostable Taq DNA polymerase at an analogous position in the thumb domain, converts the Taq DNA polymerase from a low processive to a highly processive enzyme. Processivity is dependent on the presence of thioredoxin. The enhancement in processivity is 20-50-fold when compared with the wild-type Taq DNA polymerase or to the recombinant polymerase in the absence of thioredoxin. The recombinant Taq DNA pol/TBD is thermostable, PCR competent and able to copy repetitive deoxynucleotide sequences six to seven times more faithfully than Taq DNA polymerase and makes 2-3-fold fewer AT-->GC transition mutations.

Amino Acid Sequence↗

PubMed2003

Epithelial Na, K-ATPase expression is down-regulated in canine prostate cancer; a possible consequence of metabolic transformation in the process of prostate malignancy.

BACKGROUND: An important physiological function of the normal prostate gland is the synthesis and secretion of a citrate rich prostatic fluid. In prostate cancer, citrate production levels are reduced as a result of altered cellular metabolism and bioenergetics. Na, K-ATPase is essential for citrate production since the inward Na+ gradients it generates are utilized for the Na+ dependent uptake of aspartate, a major substrate for citrate synthesis. The objective of this study was to compare the expression of previously identified Na, K-ATPase isoforms in normal canine prostate, benign prostatic hyperplasia (BPH) and prostatic adenocarcinoma (PCa) using immunohistochemistry in order to determine whether reduced citrate levels in PCa are also accompanied by changes in Na, K-ATPase expression. RESULTS: Expression of Na, K-ATPase alpha1 and beta1 isoforms was observed in the lateral and basolateral plasma membrane domains of prostatic epithelial cells in normal and BPH prostates. Canine kidney was used as positive control for expression of Na, K-ATPase alpha1 and gamma isoforms. The alpha1 isoform was detected in abundance in prostatic epithelial cells but there was no evidence of alpha2, alpha3 or gamma subunit expression. In advanced PCa, Na, K-ATPase alpha1 isoform expression was significantly lower compared to normal and BPH glands. The abundant basolateral immunostaining observed in normal and BPH tissue was significantly attenuated in PCa. CONCLUSION: The loss of epithelial structure and function and the transformation of normal epithelial cells to malignant cells in the canine prostate have important implications for cellular metabolism and are accompanied by a down regulation of Na, K-ATPase.

Journal Article↗

PubMed2003

Chondrosarcoma of bone complicating Ollier's disease: report of a favourable response to radiotherapy.

Because chondrosarcoma of bone is traditionally thought to be a radioresistant malignancy, it is usually managed surgically. We report a case of multifocal chondrosarcoma arising in Ollier's disease for which the patient declined surgery. He was given a course of radical radiotherapy that resulted in symptom palliation and a radiologically confirmed response before he died of disseminated disease. In patients with inoperable chondrosarcoma, radiotherapy can provide palliative benefit.

Bone Neoplasms↗

PubMed2003

Optimizing the search algorithm for protein engineering by directed evolution.

An in silico protein model based on the Kauffman NK-landscape, where N is the number of variable positions in a protein and K is the degree of coupling between variable positions, was used to compare alternative search strategies for directed evolution. A simple genetic algorithm (GA) was used to model the performance of a standard DNA shuffling protocol. The search effectiveness of the GA was compared to that of a statistical approach called the protein sequence activity relationship (ProSAR) algorithm, which consists of two steps: model building and library design. A number of parameters were investigated and found to be important for the comparison, including the value of K, the screening size, the system noise and the number of replicates. The statistical model was found to accurately predict the measured activities for small values of the coupling between amino acids, K <or= 1. The ProSAR strategy was found to perform well for small to moderate values of coupling, 0 <or= K <or= 3, and was found to be robust to noise. Some implications for protein engineering are discussed.

Algorithms↗