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Biomedical subjects

R J Osborne

Publications and source records attributed to R J Osborne.

At least 19 recordsLinked to original sources
PubMed2006

Expression profile of FSHD supports a link between retinal vasculopathy and muscular dystrophy.

BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is caused by deletions within a tandem array of D4Z4 repeats on chromosome 4q35. In addition to muscle degeneration, most patients with FSHD develop abnormalities of the retinal vasculature. Previous work has suggested that muscle degeneration in FSHD results from increased expression of genes proximal to the deletion, including FRG1. OBJECTIVES: To reexamine this mechanism and identify pathways that are abnormally regulated early in the disease process. METHODS: We prospectively studied gene expression in skeletal muscle in patients with FSHD (n = 19) vs healthy individuals (n = 30) and patients with myotonic dystrophy type 1 (n = 12). We used oligonucleotide microarrays for global analysis of gene expression and reverse transcriptase-PCR (RT-PCR) to assess expression or alternative splicing for particular genes. RESULTS: Expression of FRG1 was not increased in patients with FSHD, either by microarray analysis or quantitative RT-PCR. Among genes on 4q35, only LRP2BP showed upregulation that was specific to FSHD. However, neither LRP2BP nor FRG1 showed imbalance of allelic expression by RT-PCR. After filtering out genes that showed similar dysregulation in other forms of muscular dystrophy, only 44 genes were specifically upregulated early in FSHD. Among these, 34 genes were characterized or partially characterized, of which 11 (32%) had a role in vascular smooth muscle or endothelial cells. CONCLUSION: Expression of genes on chromosome 4q35 was normally regulated in the early stages of facioscapulohumeral muscular dystrophy. Our results support a possible link between muscular dystrophy and retinal vasculopathy in facioscapulohumeral muscular dystrophy.

Adolescent↗
PubMed2000

A genome-wide map showing common regions of loss of heterozygosity/allelic imbalance in breast cancer.

We report here a new framework map that integrates data from 143 studies on the loss of heterozygosity/allelic imbalance in breast cancer. Full details of these loss of heterozygosity maps can be found at the web site (http://www.nottingham.ac.uk/pdzmgh/loh/) that accompanies this report. By combining results from these data, we have also been able to highlight and identify minimum commonly deleted regions on each chromosome. In addition to finding commonly deleted regions at both the BRCA1 and BRCA2 loci, which confirmed the power of the technique, 24 other regions were identified on 16 different chromosomes.

Alleles↗
PubMed1997

Mapping of the Heliothis armigera entomopoxvirus (HaEPV) genome, and analysis of genes encoding the HaEPV spheroidin and nucleoside triphosphate phosphohydrolase I proteins.

The genome of Heliothis armigera entomopoxvirus (HaEPV) has been mapped with four restriction endonuclease enzymes (BamHI, HindIII, PstI and XhoI), and its length estimated at 233 kbp. An EcoRI-generated HaEPV genomic fragment hybridized to all fragments identified as genomic termini, providing the first experimental evidence for the presence of terminal repeat elements in an EPV genome. The HaEPV spheroidin and nucleoside triphosphate phosphohydrolase I (NPHI) genes have been cloned and sequenced, and their deduced products shown to possess high levels of identity with homologues from other Genus B entomopoxviruses (EPVs). The genomic locations of these and other HaEPV genes and open reading frames have been determined; comparison of their locations with those of homologues in the Amsacta moorei EPV genome largely supports an hypothesis that the Genus B EPVs share a conserved genomic organization which differs from that of chordopoxviruses. It is proposed that genes of EPVs can be assigned to five actual or predicted homology-based groups, a categorization which is useful for directing and interpreting investigations of EPV gene functions and relationships.

Acid Anhydride Hydrolases↗
PubMed1996

Cell lines from the melolonthine scarab Antitrogus parvulus.

Continuously replicating cell lines have been established from embryonic tissue and circulating hemolymph cells of the melolonthine Antitrogus parvulus Britton. Isozyme analyses demonstrated that cell lines from both tissue sources expressed essentially the same isoforms of enzymes as A. parvulus larvae and thus confirmed the species of their origin. Karyotype analyses showed that cells from both tissue sources had accumulated changes in chromosome number and morphology during culture. Availability of melolonthine-derived cells should assist in vitro studies of the pathogens of this important group of beetles.

Animals↗
PubMed1996

An entomopoxvirus homologue of the vaccinia virus D13L-encoded 'rifampicin resistance' protein.

The Heliothis armigera entomopoxvirus (HaEPV) genome encodes a predicted 68 kDa polypeptide related to the 'rifampicin resistance' protein of vaccinia virus (with 30 % identity), and an homologous swinepox virus protein (27% identity). We were unable to isolate an HaEPV genotypic variant encoding a predicted C-terminal truncated form of the protein, suggesting that the C terminus of the molecule may be essential to protein function, and, in turn, that this function may be essential to viral replication. HaEPV replication was substantially reduced in host cells exposed to rifampicin, but the observed cytotoxic properties of the drug made it impossible to determine the specific cause of that inhibition. We suggest that possession of a gene encoding a member of this polypeptide family might represent a defining molecular characteristic of the Poxviridae.

Amino Acid Sequence↗
PubMed1996

Phase I study of etoposide with SDZ PSC 833 as a modulator of multidrug resistance in patients with cancer.

PURPOSE: To determine the maximum-tolerated dose (MTD) and toxicity of PSC 833 infusion administered with etoposide for 5 days in patients with cancer, and to determine the effect of PSC 833 on etoposide pharmacokinetics. PATIENTS AND METHODS: Thirty-five patients were entered onto the study, one of whom was ineligible. Etoposide was delivered from day 1 as a 2-hour infusion over 5 consecutive days at a dose of 75 to 100 mg/m2/d. PSC 833 was administered from day 2 as a 2-hour loading dose and as a 5-day continuous infusion. Doses were escalated from 1 to 2 mg/kg (loading dose) and 1 to 15 mg/kg/d (continuous infusion). RESULTS: Thirty-four patients were treated with 53 cycles of PSC 833 and etoposide. Steady-state blood PSC 833 levels more than 1,000 ng/mL were achieved in all patients treated at PSC 833 doses > or = 6.6 mg/kg/d by continuous infusion. Myelosuppression was the most common toxicity. The major dose-related toxicity of PSC 833 was reversible hyperbilirubinemia, which occurred in 83% of cycles. The dose-limiting toxicity of PSC 833 was severe ataxia, which occurred in two of nine patients treated at 12 mg/kg/d and in both of the single patients treated at 13.5 and 15 mg/kg/d. PSC 833 concentrations more than 2,000 ng/mL resulted in an increase in etoposide area under the curve (AUC) of 89%, a decrease in etoposide clearance (Cl) of 45%, a decrease in volume of steady-state distribution (Vss) of 41%, and an insignificant increase in alpha half-life (t 1/2 alpha) and significant increase of beta half-life (t 1/2 beta) of 19% and 77%, respectively. CONCLUSION: PSC 833 can be administered in combination with etoposide with acceptable toxicity. The recommended continuous infusion dose of PSC 833 for this schedule is 10 mg/kg/d over 5 days. PSC 833 results in an increase in etoposide exposure and etoposide doses should be reduced in patients receiving PSC 833.

Adolescent↗
PubMed1995

Molecular genetic analysis of the von Hippel-Lindau disease (VHL) tumour suppressor gene in gonadal tumours.

Chromosome 3p allele loss is frequent in ovarian and testicular tumours. The von Hippel-Lindau (VHL) disease tumour suppressor gene maps to chromosome 3p25. Gonadal tumours may occur in patients with VHL disease, so somatic VHL gene mutations might be involved in the pathogenesis of sporadic gonadal tumours. To investigate this hypothesis, we screened 60 gonadal tumours (36 ovarian and 24 testicular) for VHL gene mutations and chromosome 3p allele loss. Although 38% (10/26) of informative ovarian and 54% (7/13) of testicular tumours demonstrated 3p allele loss, no somatic VHL gene mutations were detected in the 60 gonadal tumours analysed. This suggested that chromosome 3p tumour suppressor gene(s) other than VHL are involved in gonadal tumorigenesis.

Chromosome Deletion↗
PubMed1994

5-fluorouracil and folinic acid-induced mucositis: no effect of oral glutamine supplementation.

In some clinical situations the endogenous production of glutamine may be insufficient to maintain optimal tissue structure and function such that glutamine becomes a conditionally essential amino acid. Studies in laboratory animals have demonstrated that glutamine supplementation can reduce the incidence and severity of cytotoxic-induced mucositis. This study examined the role of oral glutamine supplementation in the management of mucositis caused by 5-fluorouracil (5-FU) and folinic acid. Twenty-eight patients with gastrointestinal cancers were randomised to receive 16 g of glutamine per day for 8 days, or placebo, in a randomised double-blind trial before crossing over to the alternative supplement during the second treatment cycle. The supplement was well tolerated with no apparent adverse effects, but failed to have any significant effect on oral mucositis assessed by the patients or investigator. The possible reasons for this apparent lack of benefit are discussed.

Administration, Oral↗
PubMed1994

Etoposide-induced cell cycle delay and arrest-dependent modulation of DNA topoisomerase II in small-cell lung cancer cells.

As an approach to the rational design of combination chemotherapy involving the anti-cancer DNA topoisomerase II poison etoposide (VP-16), we have studied the dynamic changes occurring in small-cell lung cancer (SCLC) cell populations during protracted VP-16 exposure. Cytometric methods were used to analyse changes in target enzyme availability and cell cycle progression in a SCLC cell line, mutant for the tumour-suppressor gene p53 and defective in the ability to arrest at the G1/S phase boundary. At concentrations up to 0.25 microM VP-16, cells became arrested in G2 by 24 h exposure, whereas at concentrations 0.25-2 microM G2 arrest was preceded by a dose-dependent early S-phase delay, confirmed by bromodeoxyuridine incorporation. Recovery potential was determined by stathmokinetic analysis and was studied further in aphidicolin-synchronised cultures released from G1/S and subsequently exposed to VP-16 in early S-phase. Cells not experiencing a VP-16-induced S-phase delay entered G2 delay dependent upon the continued presence of VP-16. These cells could progress to mitosis during a 6-24 h period after drug removal. Cells experiencing an early S-phase delay remained in long-term G2 arrest with greatly reducing ability to enter mitosis up to 24 h after removal of VP-16. Irreversible G2 arrest was delimited by the induction of significant levels of DNA cleavage or fragmentation, not associated with overt apoptosis, in the majority of cells. Western blotting of whole-cell preparations showed increases in topoisomerase II levels (up to 4-fold) attributable to cell cycle redistribution, while nuclei from cells recovering from S-phase delay showed enhanced immunoreactivity with an anti-topoisomerase II alpha antibody. The results imply that traverse of G1/S and early S-phase in the presence of a specific topoisomerase II poison gives rise to progressive low-level trapping of topoisomerase II alpha, enhanced topoisomerase II alpha availability and the subsequent irreversible arrest in G2 of cells showing limited DNA fragmentation. We suggest that protracted, low-dose chemotherapeutic regimens incorporating VP-16 are preferentially active towards cells attempting G1/S transition and have the potential for increasing the subsequent action of other topoisomerase II-targeted agents through target enzyme modulation. Combination modalities which prevent such dynamic changes occurring would act to reduce the effectiveness of the VP-16 component.

Bromodeoxyuridine↗
PubMed1994

Polymerase chain reaction allelotyping of human ovarian cancer.

We have used a set of microsatellite polymorphisms (MSPs) to examine the location and frequency of allele loss throughout the genome in a panel of 25 human epithelial ovarian tumours. When more than one MSP was employed per arm, mean informativity was 85.2% (range 64-100%). The average fractional allelic loss was 0.28 (range 0-0.65). A high frequency of allele loss was seen at 5q (40%), 9q (48%), 11p (43%), 14q (46%), 15q (40%), 17p (61%), 17q (64%), 19p (45%) and Xp (40%), confirming previous findings at some sites, but also suggesting the existence of new tumour-suppressor genes in regions (9q, 14q, 15q) which have not previously been studied in ovarian cancer. For 9q and 14q, partial loss of the arm was more common than loss of heterozygosity for all loci. There was a significant relationship between allele loss affecting the short arm of chromosome 17 and allele loss affecting 17q (P < 0.001). No other relationship was detected between allele losses at different sites. Polymerase chain reaction allelotyping is suitable for the examination of very small tumour samples and tumours in which classical karyotyping is problematic.

Alleles↗
PubMed1994

Measurements of resting energy expenditure and body composition before and after treatment of small cell lung cancer.

BACKGROUND: Many patients with small cell lung cancer are reported to lose weight, but the mechanism of this effect is unclear. PATIENTS AND METHODS: Measurements of resting energy expenditure (REE), using indirect calorimetry and body composition (fat, fat-free mass and organ mass), using dual energy X-ray absorptiometry (DXA) and abdominal CT scans were measured in 38 patients with newly-diagnosed small cell lung cancer. Twenty-eight patients were restudied at the end of treatment. RESULTS: In those who responded to treatment there was no change in body weight, but a decrease in REE of 15.7 +/- 11.7 kJ/kg fat free mass/day, whilst in the non-responders body weight decreased 4.33 +/- 5.4 kg, but REE was unchanged. CONCLUSIONS: This study provides evidence for tumour-induced hypermetabolism which is independent of changes in gross body composition, although the absolute increase is small, approximately 0.8 MJ/day. However since body weight was maintained in those patients who responded to treatment either total energy expenditure was decreased, implying decreases in physical activity, or energy intake was increased.

Absorptiometry, Photon↗
PubMed1994

A randomized trial of two etoposide schedules in small-cell lung cancer: the influence of pharmacokinetics on efficacy and toxicity.

PURPOSE: Etoposide is a schedule-dependent drug, as demonstrated by the superiority of 5 consecutive daily infusions over a continuous 24-hour infusion in patients with small-cell lung cancer. A randomized trial has therefore been conducted to compare an extended 8-day regimen with the 5-day schedule. PATIENTS AND METHODS: Ninety-four patients with small-cell lung cancer (35 limited disease, 59 extensive disease) were randomized to receive single-agent etoposide 500 mg/m2, either as 5 daily 2-hour infusions of 100 mg/m2 or as 8 daily 75-minute infusions of 62.5 mg/m2, both repeated every 3 weeks for six cycles. Single-agent carboplatin was administered at relapse in both arms of the study. Patients were stratified at randomization according to extent of disease and Karnofsky performance status (KPS). RESULTS: The overall response rate was 81% in the 5-day arm and 87% in the 8-day arm, with median survival durations of 7.1 and 9.4 months, respectively (no significant differences). The time over which plasma etoposide exceeded low plasma concentrations was significantly longer in patients who responded compared with patients who did not respond. This was most significant for time at concentrations greater than 1, 1.5, and 2 micrograms/mL. Hematologic toxicity was significantly worse in the 5-day arm of the study (cycle no. 1 nadir neutrophil count, 0.8 x 10(9)/L v 1.7 x 10(9)/L). Stepwise regression analysis found duration of exposure to plasma etoposide greater than 3 micrograms/mL to be predictive of nadir neutrophil count and duration of exposure to plasma etoposide greater than 2 micrograms/mL to be predictive of nadir WBC count. CONCLUSION: The 5-day and 8-day regimens had equivalent activity in small-cell lung cancer. A pharmacokinetic association between concentrations of etoposide and response and toxicity was found. Antitumor activity was associated with the maintenance of lower levels of etoposide than found to be associated with hematologic toxicity. This supports the hypothesis that the schedule of etoposide administration may affect efficacy and toxicity, and that prolonged exposure to low concentrations of etoposide may improve the therapeutic ratio for this drug.

Adult↗
PubMed1993

A deletion unit on chromosome 17q in epithelial ovarian tumors distal to the familial breast/ovarian cancer locus.

Linkage analysis in familial breast and ovarian cancer and studies of allelic deletion in sporadic ovarian tumors have suggested that chromosome 17q may be the location of a gene of importance in ovarian carcinogenesis. We have examined tumor and normal DNA samples from 120 patients with ovarian tumors for allelic deletion at 12 loci on chromosome 17q. Allelic deletion was observed in 64 cases (53%) of which 56 showed loss of heterozygosity at all loci analyzed on 17q. The pattern of allele loss at metastatic sites was consistent with loss of heterozygosity having occurred prior to metastasis. A common region of deletion, defined by 6 cases of invasive epithelial ovarian cancer and a benign serous cystadenoma, spanned 16 cM and was delimited by nm23 and GH. This region is distal to the region on chromosome 17q to which the familial breast/ovarian cancer susceptibility gene has been mapped. The results suggest that a tumor suppressor gene involved in sporadic ovarian carcinogenesis is located on the distal portion of chromosome 17q and is distinct from the gene linked to familial cases.

Alleles↗
PubMed1993

Phase II study of carboplatin and adriamycin as second line chemotherapy in small cell lung cancer.

A total of 25 patients with small cell lung cancer (SCLC) were treated with carboplatin and Adriamycin (CA) following symptomatic relapse after initial therapy, or because of static or progressive disease during primary treatment. Nine patients had disease within the thorax, and 16 had extensive metastases at relapse. The overall response rate to CA was 64% (20% complete response: CR; 44% partial response: PR). Survival from presentation in 22 of the patients who have died was 6-36 months (median 13 months), and the median survival from the commencement of CA was 23 weeks (range 1 week-11.5 months). The duration of CR was 4-8 months, and of PR 2-7 months. Hospital admission was required following 12% of cycles for management of the complications of treatment. The increasing use of first line regimens of short duration means that reassessment should be made of the activity of further therapy at relapse.

Adult↗
PubMed1991

Mutations in the p53 gene in primary human breast cancers.

Twenty-six primary breast tumors were examined for mutations in the p53 tumor suppressor gene by an RNase protection assay and nucleotide sequence analysis of PCR-amplified p53 complementary DNAs. Each method detected p53 mutations in the same three tumors (12%). One tumor contained two mutations in the same allele. Single strand conformation polymorphism analysis of genomic DNA and complementary DNA proved more sensitive in the detection of mutations. Combining this technique with the other two a total of 12 mutations in the p53 gene were demonstrated in 11 tumors (46%), and a polymorphism at codon 213 was detected in another tumor. Loss of heterozygosity on chromosome 17p was detected by Southern blot analysis in 30% of the tumor DNAs. Not all of the tumors containing a point mutation in p53 also had loss of heterozygosity of the remaining allele, suggesting that loss of heterozygosity may represent a later event.

Base Sequence↗