Biomedical subjects

John Hay

Publications and source records attributed to John Hay.

23 records · Page 2Linked to original sources

PubMed2002

Physical and functional interaction between the varicella zoster virus IE63 and IE62 proteins.

The varicella zoster virus (VZV) IE63 protein is required for growth of the virus in cell culture and is expressed during both lytic and latent phases of VZV infection. We have investigated the physical and functional interaction of this protein with the major VZV transactivating protein IE62. The region of the IE63 protein required for interaction with the IE62 protein has been identified and encompasses the N-terminal 142 amino acids. We have found that the interaction is stable at physiological ionic strength. We have also shown that a portion of the IE63 and IE62 proteins colocalize in VZV-infected cells at both 15 and 48 h postinfection. IE63 was found to have no transcriptional activating or repressing activity within the context of a minimal VZV glycoprotein promoter. The presence of the IE63, however, upmodulated the IE62 transactivation of this promoter. Finally, we show that the IE63 protein can be coimmunoprecipitated with the cellular RNA polymerase II from infected cell extracts, indicating that it is present in a complex with that enzyme.

Binding Sites↗

PubMed2002

A pilot study evaluating the safety and microbiologic efficacy of an economically viable antimicrobial lozenge in patients with head and neck cancer receiving radiation therapy.

BACKGROUND: Mucositis occurs in almost all radiotherapy-treated head and neck cancer patients, in approximately 75% of patients receiving hematopoietic marrow transplantation, and in approximately 40% of all patients who receive chemotherapy. Mucositis is painful, may affect all oral functions, and is a dose- and rate-limiting toxicity of therapy for cancer. Radiation-associated mucositis (onset, intensity, and duration) has been shown in recent clinical trials to be modified by the use of antibacterial/antifungal lozenges. PURPOSE: The aim of this collaborative two-center phase II study was to assess the toxicity and microbiologic efficacy of an economically viable antimicrobial lozenge in the management of patients receiving radiation therapy for head and neck cancer. MATERIALS AND METHODS: Seventeen patients scheduled to receive radical or postoperative radiotherapy were provided with bacitracin, clotrimazole, and gentamicin (BCoG) lozenges (one lozenge dissolved in the mouth qid from day 1 of radiotherapy until completion). Ease of use and palatability of the lozenges, patients' symptoms (swallowing and pain), and quantitative and qualitative microbiologic evaluation of an oral rinse collection was conducted at least once weekly during radiation therapy. RESULTS: No significant side effects were reported from the use of the lozenges. The lozenges were well tolerated at the beginning of treatment by all patients, with some minor difficulty associated with oral discomfort toward the end of the treatment. Microbiologic evaluation showed consistent elimination of yeast organisms in all patients. In four patients there was no growth of gram-negative bacilli on culture, whereas in two patients, fluctuating counts were seen, and one patient had increased counts. The remaining patients had significant reduction in the gram-negative bacilli counts. CONCLUSIONS: This study demonstrated that the BCoG lozenge is tolerable and microbiologically efficacious, achieving elimination of Candida in all patients and reduction in gram-negative flora in most patients. A phase III study is underway to evaluate the clinical efficacy of this lozenge.

Administration, Oral↗

PubMed2002

Short-course preoperative radiation therapy for operable rectal cancer.

BACKGROUND: Short course neoadjuvant radiation has been shown to provide improved local control of rectal cancer in a clinical trial population even in the presence of standardized surgical techniques. However, this use of hypofractionated radiotherapy has been limited in North America owing to concerns over toxicity. METHODS: Patients considered to have locally advanced rectal carcinoma received a radiation dose of 25 Gy given in five fractions to the posterior pelvis. Definitive surgery was then performed within 2 weeks. Retrospective analysis was performed. RESULTS: Sixty-three patients, of whom 60 were assessable, were treated with preoperative short course radiotherapy at the British Columbia Cancer Agency between 1991 and 1998, and 97% proceeded to R0 resection. Local recurrence developed in 3 patients (5%). Five-year actuarial overall and relapse-free survival rates for the group were 71% and 69%, respectively. The actuarial rates of relapse-free survival by stage at 5 years were stage 1 83%, stage II 75%, stage III 62%, and stage 4 0%. Eleven patients (18%) experienced a postoperative complication. CONCLUSION: Short course preoperative radiotherapy for operable rectal cancer can be delivered to a general population and produce high pelvic control rates with acceptable toxicity.

Adult↗

PubMed2002

Memory cytotoxic T cell responses to viral tegument and regulatory proteins encoded by open reading frames 4, 10, 29, and 62 of varicella-zoster virus.

Cytotoxic T cell recognition of tegument and regulatory proteins encoded by open reading frames (ORFs) 4, 10, 29, and 62 of varicella-zoster virus (VZV) was evaluated using limiting dilution conditions to estimate the precursor frequencies of memory T cells specific for these proteins in immune subjects. Responder cell frequencies for ORFs 4, 10, and 62 gene products, which are virion tegument components and function as immediate early viral transactivating proteins, were equivalent. CTLp recognition of VZV proteins made in latently infected cells, which include ORF4 and ORF62 proteins, was not maintained preferentially when compared to ORF10 protein, which has not been shown to be expressed during latency. T cell recognition of ORF29 protein, the major DNA binding protein, which is expressed during replication but not incorporated into the virion tegument, was less common than responses to ORFs 4, 10, and 62 gene products. Older individuals had diminished numbers of memory CTLp that lysed autologous targets expressing IE62 protein; these responses were increased after immunization with live attenuated varicella vaccine to the range observed in younger adults. Adaptive immunity to VZV is characterized by a broad repertoire of memory CTL responses to proteins that comprise the virion tegument and regulate viral gene expression in infected cells.

Adult↗

PubMed2002

Glucocorticoids inhibit lung cancer cell growth through both the extracellular signal-related kinase pathway and cell cycle regulators.

Glucocorticoids inhibit the proliferation of various cell types, but the mechanism of this inhibition remains unclear. We investigated the effect of dexamethasone on non-small cell lung cancer cell growth and cell cycle progression. We showed that dexamethasone suppresses the proliferation of A549 and Calu-1 cells, with accumulation of cells in G1/G0 stage of the cell cycle, as determined by fluorescence-activated cell sorter analysis. Western blot analysis confirmed that this is associated with hypophosphorylation of retinoblastoma protein. Using Western blot analysis and in vitro kinase assays, we found that dexamethasone results in decreased activity of CDK2 and 4, decreased levels of cyclin D, E2F, and Myc, and increased levels of the CDK inhibitor p21(Cip1). In addition, we found that dexamethasone decreases activity of extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK). The kinetics of all these changes indicate that inhibition of the ERK/MAPK pathway precedes the cell cycle effects, suggesting that regulation of this MAPK-signaling pathway may be an alternative mechanism for glucocorticoid-induced cell cycle arrest and growth inhibition.

Cell Cycle↗