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Biomedical subjects

M Rice

Publications and source records attributed to M Rice.

At least 37 records · Page 2Linked to original sources
PubMed1998

Analysis of factors influencing kinetics of herpes simplex virus transcription utilizing recombinant virus.

The herpes simplex virus type 1 (HSV-1) transcription program is a regulated cascade in which early and late phases of gene expression are separated by viral DNA replication. While promoters controlling expression of transcripts encoding immediate-early proteins contain virus-specific cis-acting elements, these are in the context of cellular promoter elements, and the promoters controlling expression of other viral transcripts contain only cellular cis-acting elements. We had developed and continue to refine a general method for the production of recombinant viruses in which modified promoters can be inserted into nonessential loci within the viral genome through homologous recombination. This approach has been especially useful in defining the features of model promoters of the various kinetic classes. Our work suggests that class-specific differences in promoter architecture are critical factors in the ability of the cellular transcription machinery to form stable preinitiation complexes at various phases of infection and, thus, mediate kinetic class-specific transcription. Early (beta) promoters contain a TATA box and upstream activation elements while sequences downstream of the TATA homology are dispensible for transcription. Late transcripts can be catagorized as either leaky-late (beta gamma) or strict late (gamma) depending on whether they are readily detectable prior to viral DNA replication. Promoters controlling both types are clearly distinct from early ones in that sequences near the transcription start site which resemble consensus mammalian initiator elements are required along with the TATA box and activator elements. Strict late promoters do not contain elements upstream of the TATA box but include what appears to be a class specific element downstream of the transcription start site.

DNA Replication↗
PubMed1998

Influence of parental and family adjustment on the later psychological adjustment of children treated for cancer.

OBJECTIVE: To examine the relationship between parental adjustment and family adjustment during the period after the children's diagnosis of cancer and the psychological adjustment of children 2 years after their diagnosis. METHOD: The study used a prospective design. Children aged 2 to 5 years with cancer and their parents and families (n = 38) were assessed immediately after the children's diagnosis and again 2 years after the diagnosis. Path analysis was used to investigate the relationship between parental and family adjustment during the period after diagnosis and the psychological adjustment of the children 2 years after their diagnosis. RESULTS: Maternal adjustment during the period after the children's cancer was diagnosed had a significant relationship with the children's psychological adjustment 2 years after diagnosis. In contrast, the adjustment of fathers and family adjustment appeared to have a more limited impact on the later psychological adjustment of the children. CONCLUSION: The level of distress experienced by mothers after the children's diagnosis may have an important influence on the later psychological adjustment of the children. It is possible that this is due to the impact of maternal distress on the capacity of mothers to care for their children during the children's treatment for cancer.

Adaptation, Psychological↗
PubMed1998

Daytime CPAP titration: a viable alternative for patients with severe obstructive sleep apnea.

OBJECTIVE: Continuous positive airway pressure (CPAP) is the treatment of choice for patients diagnosed with severe obstructive sleep apnea (OSA). The implementation of CPAP therapy has traditionally been based on full-night titration studies or split-night protocols. This study compared a group of patients who received a regular nocturnal CPAP titration with patients who received a daytime CPAP titration. The objective of the study was to determine if daytime CPAP titration is a viable alternative for the implementation of CPAP treatment in patients with severe OSA. STUDY DESIGN: Fourteen patients (13 men and one woman) received a daytime CPAP titration (day group). The day group was matched to 18 patients (17 men and one woman) who were titrated under a full-night regular nocturnal study (night group). Eligible patients were those with severe OSA (respiratory event index > 40). The groups were matched by age, sex, and body mass index. RESULTS: Daytime and nocturnal CPAP titration studies yielded sufficient amounts of rapid eye movement (REM) and non-REM sleep to help determine CPAP settings. Importantly, the diurnal and nocturnal CPAP titrations resulted in comparable therapeutic pressures as well as comparable resolution of sleep-disordered breathing. After 1 week of treatment, the groups exhibited similar CPAP use and comparable improvements in subjective sleepiness as indicated by their increase in sleep/wake activity inventory scores. CONCLUSIONS: Daytime CPAP titration studies may be a viable alternative for the efficient and expedient implementation of CPAP therapy among some patients with severe OSA.

Adult↗
PubMed1997

A novel link between REC2, a DNA recombinase, the retinoblastoma protein, and apoptosis.

The REC2 recombinase is essential for recombinational repair following DNA damage as well as for successful meiosis and gene targeting in the corn smut Ustilago maydis. Here we report that overexpression of REC2 induced apoptotic cell death in human HuH-7, Hep G2, and Hep 3B hepatoma cells. Apoptosis was related to recombinase activity and was significantly increased by inhibition of retinoblastoma (Rb) expression with transforming growth factor-beta1. REC2-induced apoptosis was associated with a significantly reduced percentage of cells in the G1 phase of the cell cycle and a significant reduction in G2/M only in the Rb(-/-) Hep 3B cells. Overexpression of REC2 resulted in increased abundance of the hyperphosphorylated form of Rb. However, by immunoprecipitation REC2 was associated primarily with hypophosphorylated Rb, suggesting that REC2 may be involved in modulating the phosphorylation state of Rb. The A and B pocket domains with the spacer amino acid sequence and the carboxyl-terminal region of Rb were required for maximal binding to REC2. Overexpression of Rb significantly inhibited REC2-induced apoptosis even in the presence of transforming growth factor-beta1. Taken together, these data suggest a novel interaction of Rb with the recombinase REC2 and a role for this complex in bridging DNA recombination and apoptosis.

Apoptosis↗
PubMed1997

The cloning and overexpression of a cruciform binding protein from Ustilago maydis.

The structural gene HMP1 encoding a cruciform DNA binding protein from Ustilago maydis has been cloned. Gene isolation was enabled by a polymerase chain reaction procedure using primers designed from amino acid sequence obtained from the purified protein. DNA sequence determination has revealed that the gene encodes a protein containing 98 amino acids with a calculated molecular weight of 10151. Comparison of the cDNA and genomic sequences indicated the presence of a single intron in the 5' coding region of the gene. The gene was over-expressed as a translational fusion with a hexahistidine leader sequence enabling affinity purification of the protein on an immobilized metal matrix. Protein isolated after over-expression exhibited cruciform binding activity, conforming earlier purified native protein results. Sequence analysis indicated that no HMG box was present and very little homology to other known cruciform binding proteins was found. It is plausible that HMP1 represents a novel class of proteins that recognize such secondary structures.

Amino Acid Sequence↗
PubMed1997

Liver hemostasis using high-intensity focused ultrasound.

Liver hemorrhage, the major cause of death in hepatic trauma, is notoriously difficult to control. We report on the use of high-intensity focused ultrasound (HIFU) to arrest the bleeding from incisions made in rabbit livers. A HIFU transducer, with a spherically curved aperture of 6.34 cm2 area, a focal length of 4 cm and a frequency of 3.3 MHz was used. In approximately 94% of the incisions, the hemorrhage was reduced to a slow oozing of blood in less than 2 min. The maximum temperature of liver tissue around the incision area, during HIFU application, was measured to be 86 degrees C. The mechanism of hemostasis, confirmed by histological examination, appears to be coagulative necrosis of a volume of liver tissue around the incision. We believe that acoustic hemostasis, with the unique characteristic of "volume cauterization," offers a novel method for the management of liver hemorrhage and, thus, has major clinical implications.

Animals↗
PubMed1997

Leukaemia presenting as marrow hypoplasia: molecular detection of the leukaemic clone at the time of initial presentation.

Occasional cases of transient marrow hypoplasia in childhood evolve into acute leukaemia. We studied two children who presented with marrow hypoplasia following infection and who developed acute lymphoblastic leukaemia 2-3 months later. A simple polymerase-chain-reaction (PCR) test for monoclonality showed that immunoglobulin heavy-chain gene rearrangements of the same size were present at the times of both hypoplasia and leukaemia, and DNA sequencing confirmed identity of these rearrangements. PCR-based quantification, using patient-specific primers, showed in both patients that the leukaemic clone made up 20-25% of the marrow cells during hypoplasia. In contrast, four patients with typical aplastic anaemia showed only polyclonal B-cell populations in the marrow. We conclude that the leukaemic clone was already present at the time of hypoplasia in the two index patients and that in future a simple PCR test for monoclonality could be used to screen patients with marrow aplasia or hypoplasia for the presence of a monoclonal B-cell population. Patients with monoclonal populations could then be monitored carefully for subsequent development of leukaemia.

Anemia, Aplastic↗
PubMed1997

The neuroprotective effect of the forebrain-selective NMDA antagonist CP101,606 upon focal ischemic brain damage caused by acute subdural hematoma in the rat.

The neuroprotective effects of drugs that act against excitotoxic damage, caused by glutamate, are well described in focal ischemia, but behavioral effects, and apparent failure in clinical trials of "first-generation" competitive N-methyl D-aspartate (NMDA) antagonists, such as Selfotel (CGS19755), has led to interest in evaluating newer NMDA antagonists with fewer behavioral effects. We have therefore evaluated the neuroprotective effect of a new forebrain-selective polyamine site NMDA antagonist, CP101,606 in a rat subdural hematoma (SDH) model. An SDH was produced by slow injection of 0.4 ml autologous blood into the parietal subdural space. Brain damage was assessed histologically at eight coronal planes, in animals sacrificed 4 h after induction of hematoma. The drug was infused 30 min after induction of SDH. The reductions of ischemic brain damage achieved by CP101,606, was 29% for the low dose and 37% for the high dose. This novel glutamate antagonist has shown a magnitude of neuroprotection which is comparable with that seen with "first-generation" NMDA antagonists such as MK801, D-CPP-ene and CGS19755, in this same model. This new agent is claimed to have fewer psychomotor and behavioral effects than MK801, D-CPP-ene, and CGS19755.

Animals↗
PubMed1997

Childhood cancer: a two-year prospective study of the psychological adjustment of children and parents.

OBJECTIVE: To follow prospectively the psychological adjustment of young children, parents, and families during the first 2 years after the children's diagnosis of cancer. METHOD: Children aged 2 to 5 years with cancer diagnoses and their parents and families (n = 38) were assessed immediately after diagnosis, 1 year after diagnosis, and 2 years after diagnosis. At each assessment, the psychological adjustment of the children and their families was compared with the adjustment of a cohort of children and families in the general community (n = 39). RESULTS: Children with cancer and their parents experienced significantly more emotional distress than children and parents in the community during the period immediately after diagnosis. However, the number of problems experienced by the children with cancer and their parents declined during the first year after the children's diagnosis and stabilized at a level comparable with that found among children and parents in the general community. CONCLUSION: Although the results are consistent with reports that suggest that in the longer term the prevalence of psychological problems among children with cancer is similar to that found among children in the general community, they also highlight the considerable distress experienced by children and parents during the period immediately after the children's diagnosis.

Adaptation, Psychological↗
PubMed1997

Improvement in outcome of children with Wilms' tumour in South Australia over the last 30 years.

OBJECTIVE: To evaluate the outcome of children with Wilms' tumour over the last 30 years in South Australia. To compare the outcome of children treated before and after 1982, when standard treatment protocols were introduced. METHODOLOGY: Management approaches, survival rates and side-effects of treatment were identified from case notes. Pathology slides were reviewed to ensure all children were correctly diagnosed with Wilms' tumour. RESULTS: Children treated for Wilms' tumour prior to 1982 had an overall survival rate of 54%. Since 1982 there has been a significant improvement in outcome and the current survival rate is now 85%. Children treated since 1982 have also experienced fewer treatment related side-effects than children treated prior to 1982. CONCLUSIONS: There has been substantial improvement in survival from childhood Wilms' tumour over the past 30 years in South Australia. This is likely to be due to a combination of factors including standardization of treatment, tailoring of treatment to stage and histology, improved perioperative care, enhanced radiological techniques and higher levels of collaboration between relevant specialists.

Child↗
PubMed1996

Virus and virus-like particles observed in the intestinal contents of the possum, Trichosurus vulpecula.

Intestinal contents derived from the Australian brush-tailed possum, Trichosurus vulpecula, were examined by negative stain electron microscopy for the presence of viruses. Out of 100 samples, 23 contained at least one type of vertebrate virus or virus-like particle. Adenovirus was identified in six samples, herpesvirus in two samples, coronavirus in four samples, and coronavirus-like particles in 14 samples. To date no viruses of the brush-tailed possum have been isolated in tissue culture but these results indicate that this species is probably host to several viral species.

Animals↗
PubMed1996

A 3-year follow-up of the intellectual and academic functioning of children receiving central nervous system prophylactic chemotherapy for leukemia.

This prospective study compared the intellectual and academic functioning of two groups of children treated for cancer over the 3 years after their diagnosis. One group consisted of children who received central nervous system (CNS) prophylactic chemotherapy, and the other group consisted of children with cancer who did not receive CNS chemotherapy. The results suggest that the children who received CNS chemotherapy experienced more adverse effects from their treatment in the area of academic functioning than the children who did not receive CNS chemotherapy. Although there were no differences in the academic functioning of the two groups of children immediately after their diagnosis, 3 years postdiagnosis, the CNS-treated children scored more poorly on academic tests of reading, spelling, and arithmetic than the non-CNS-treated children. The results suggest that CNS chemotherapy prophylaxis may impede academic achievement.

Adolescent↗