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Biomedical subjects

B Curran

Publications and source records attributed to B Curran.

47 records · Page 3Linked to original sources
PubMed1988

Catabolite control of the elevation of PGK mRNA levels by heat shock in Saccharomyces cerevisiae.

Heat shock enhances the very high level of transcription of the phosphoglycerate kinase (PGK) gene in fermentative cultures of Saccharomyces cerevisiae. This response of PGK mRNA levels was not found on gluconeogenic carbon sources, and could be switched on or off subject to availability of fermentable carbon source. The addition of glucose to yeast growing on glycerol resulted in acquisition, within 30-60 min, of the ability to elevate PGK mRNA levels after heat shock. In addition, in aerobic cultures growing on glucose the exhaustion of the medium glucose coincided with a loss of the heat-shock effect on PGK mRNA and a switch-over to slower growth by aerobic respiration. Levels of hsp26 mRNA were analysed during these experiments. Contrasting with this requirement for fermentable catabolite for manifestation of a heat-shock response of PGK mRNA levels, the PGK enzyme was not synthesized at a greater level in heat-shocked fermentative than in gluconeogenic cultures. PGK is one of only a few proteins made efficiently after mild heat shock of yeast. Thus, heat-stress-induced elevation of PGK mRNA levels does not appreciably increase PGK synthesis during exposure to high temperatures and so its role may be to assist cells repressed in mitochondrial function during recovery following a heat shock.

Aerobiosis↗
PubMed1987

Saccharomyces cerevisiae mRNA populations of different intrinsic stability in unstressed and heat shocked cells display almost constant m7GpppA:m7GpppG 5'-cap structure ratios.

The half-lives of mRNAs in yeast vary from about 1 to over 100 min. While mRNA stabilities must strongly influence overall gene expression in this organism, very little is known about how they are determined. Labellings of yeast cells were conducted to investigate whether the 5'-cap structures of yeast mRNAs might influence their stability. Variation of the pulse-labelling period from 7.5 min to 120 min did not have any major influence on the relative labelling of m7GpppA (A cap) and m7GpppG (G cap) in total polyadenylated RNA. Whether an mRNA has the A cap or the G cap does not therefore have a marked effect on its stability. During the heat shock response the relative labelling of A caps to G caps in total polyadenylated RNA also does not fluctuate appreciably. This indicates that cap structure alone does not determine the destabilisation of non-heat shock mRNAs and stabilisation of heat shock mRNAs during this stress response.

Heat-Shock Proteins↗
PubMed1986

Transcription of the phosphoglycerate kinase gene of Saccharomyces cerevisiae increases when fermentative cultures are stressed by heat-shock.

The single gene for phosphoglycerate kinase (PGK) in the haploid genome of Saccharomyces cerevisiae is expressed to a very high level in cultures fermenting glucose. Despite this it responds to heat-shock. When S. cerevisiae growing exponentially on glucose media was shifted from 25 degrees C to 38 degrees C transient increases of 6-7-fold in cellular PGK mRNA were observed. This elevation in PGK mRNA still occurred in the presence of the protein-synthesis inhibitor cycloheximide, but was not observed in cells bearing the rna1.1 mutation. From the kinetics of continuous labelling of PGK mRNA, relative to the labelling of other RNAs in the same cultures whose levels do not alter with heat-shock, it was shown that the elevation in PGK mRNA in response to temperature upshift reflects primarily an increased synthesis of this mRNA and not an alteration of its half-life. PGK mRNA synthesis is therefore one target of a response mechanism to thermal stress. Synthesis of PGK enzyme in glucose-grown cultures is efficient after mild (25 degrees C to 38 degrees C) or severe (25 degrees C to 42 degrees C) heat-shocks. Following the severe shock, the synthesis of most proteins is abruptly terminated, but synthesis of PGK and a few other glycolytic enzymes continues at levels comparable to the levels of synthesis of most of those proteins dramatically induced by heat (heat-shock proteins). Cells that overproduce PGK due to the presence of multiple copies of the PGK gene on a high-copy-number plasmid continue their overproduction of this enzyme during severe thermal stress. Therefore PGK mRNA is both elevated in level in response to heat-shock and translated efficiently at supra-optimal temperatures.

Cycloheximide↗
PubMed1984

Non-metastatic locally advanced cancer of the breast treated with radiation.

One hundred forty-seven female patients with retrospectively classified (AJCCS 1977) Stage III and nonmetastatic noninflammatory Stage IV breast carcinoma from June 1958 to December 1978 were studied to determine the effects of primary radiation on local recurrence and survival. Fifty-one patients recurred in the breast; 24 patients recurred in the local-regional area of breast and draining lymphatics and 15 patients recurred in the axilla only. Distant metastases developed in 97 patients. The 5 year actuarial survival was 24%. Decreased recurrence rates were associated with megavoltage and higher doses of radiation (34% vs. 65%); with smaller tumors (27% vs. 57%); with total extirpation of gross tumor (33% vs. 53%); and with those tumors that were given a "boost dose" (26% vs. 58%). The addition of systemic treatment did not appreciably alter either local-regional recurrence or survival. However, most of the patients received endocrine ablation or single-agent chemotherapy. Polyagent chemotherapy was used late in the series, making its true impact on survival difficult to evaluate.

Adenocarcinoma↗
PubMed1979

Real-time computer verification for radiation therapy treatment machines.

A computer based verification system which monitors the operation of a 4-MV linear accelerator is described. Fourteen parameters can be checked for proper alignment prior to irradiation. A training simulator was also built to minimize interference with treatment schedules and to provide technicians with experience in using the system during the developmental stages of the project.

Computers↗
PubMedDate not supplied

Remote site treatment planning.

Remote site treatment planning was one of the earliest methods of digital computer dose planning. Using batch-oriented or time-sharing mainframe computer systems, researchers in the late 1950s and early 1960s developed many of the basic algorithms used later in stand-alone systems. Although time-shared systems have continued in use, most of the emphasis on treatment planning in the last decade has been on using dedicated mini- and micro-computer systems. Recent developments in the computer industry, such as the use of networks and distributed computer processing, may lead to a resurgence of interest in remote computer systems for treatment planning.

Computer Communication Networks↗
PubMedDate not supplied

Uptake of porcine rubulavirus (LPMV) by PK-15 cells.

BACKGROUND: The porcine virus denominated La Piedad Michoacan Virus (LPMV) is a member of the family Paramyxoviridae and is the cause of a disease in pigs present only in Mexico. The disease is characterized by meningoencephalitis and respiratory distress in young pigs, epididymitis and orchitis in boars, and reproductive failure and abortion in sows. METHODS: The cytopathology, morphology, and distribution of the hemagglutination neuraminidase (HN) and nucleoprotein (NP) proteins of LPMV were investigated following inoculation into PK-15 cells. The cytopathic effect was characterized by cytoplasmic vacuolation and the formation of syncytia and cytoplasmic inclusion bodies. RESULTS: In immunofluorescence assays using a monoclonal antibody (MAb) against the HN protein at 5-60 min post-infection (early infection), a diffuse immunofluorescence was observed near the cell membrane and adjacent to the nuclear membrane. At 24 h post-infection (late infection), a dust-like immunofluorescence was observed throughout the cytoplasm. LPMV-infected cells incubated with the MAb against the NP protein showed punctate cytoplasmic fluorescence during the early stages of infection. At the late infection stage, these fluorescent particles became larger and were seen predominantly in the cytoplasm of syncytia. This pattern was also apparent by immunohistochemical labeling and immunogold electron microscopy. The latter technique revealed that HN protein was diffusely distributed throughout the cytoplasm. When using the MAb against the NP protein, nucleocapsid organization was the most prominent feature and resulted in the formation of cytoplasmic inclusion bodies visible by light and electron microscopy. Immunogold labeling of purified nucleocapsids was shown by electron microscopy. Virus particles and nucleocapsids were morphologically similar to members of the Paramyxoviridae family. CONCLUSIONS: The morphologic characteristics of the virions and the distribution patterns of the HN and NP proteins in PK-15 infected cells indicate that the mechanisms of LPMV replication are generally similar to those of the members of the Paramyxoviridae family.

Animals↗
PubMedDate not supplied

Treatment planning with a graphics tablet.

A graphics-tablet treatment planning system is described. The cost effectiveness of this approach is especially attractive where time-sharing use of a central computer facility is available.

Computers↗
PubMedDate not supplied

Feulgen-DNA content of human sperm and outcome of in vitro fertilization.

Feulgen-DNA content of sperm was quantified in fresh semen samples of 20 consecutive couples during preparation for in vitro fertilization to measure the condensation state of sperm chromatin. Results were expressed as a percentage of expected haploid DNA value (1c). No significant differences were found between those who did not get pregnant, those who went full term, and those who aborted. Because fertilization can occur with a minority of normal sperm, it is concluded that the present findings do not provide useful clinical information about pregnancy outcome and in vitro fertilization.

Coloring Agents↗