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Biomedical subjects

R J Bishop

Publications and source records attributed to R J Bishop.

11 recordsLinked to original sources
PubMed1998

Variability in visual cortex activation during prolonged functional magnetic resonance imaging.

This study was conducted to test whether cortical activation varies across successive epoques during functional magnetic resonance imaging (fMRI) studies. Ten normal adult volunteers were studied with a 1.5-T MR scanner. Pseudocoronal study planes were chosen perpendicular to the tentorium cerebelli, at two thirds the distance from the posterior edge of the splenium of the corpus callosum to the transverse sinuses. Functional images were acquired with a T2*-weighted spoiled gradient echo sequence. The visual cortex was stimulated by goggles flashing at 8 Hz. Each study consisted of 82 sequential scans, lasting 15 seconds each for a total of 20.5 minutes. Two scans without stimulation were alternated with two scans of visual stimulation. Scans 3 through 83 were divided into five sequences of 16 scans. For each sequence, the number of pixels within a predefined rectangular region of interest that showed increased activity during stimulation were counted. Least squares regression models of straight lines were fit to the data. The initial level of visual cortex activation in the region of interest, as measured by the y-intercept, varied substantially from subject to subject (range: 4-68, p < 0.001). There was sufficient evidence of systematic change with time to reject the hypothesis of constant activation with the same stimulus over time (p=0.02). The observed visual cortex activation with single-plane fMRI varied both with time over successive epoques and among subjects. Possible factors responsible for the variation may include head movement, eyelid position, attention, and physiologic fatigue. These factors must be accounted for in experimental design and in data analysis and interpretation.

Adult↗
PubMed1993

Inaccurate haemoglobin estimation in Waldenström's macroglobulinaemia: unusual reaction with monomeric IgM paraprotein.

Automated blood counts from a patient with Waldenström's macroglobulinaemia repeatedly failed critical limit standards set for mean cell haemoglobin concentration and mean cell haemoglobin. Haemoglobin estimation was higher than that suggested by clinical examination, symptoms, and the spun haematocrit. This was found to be due to an interaction between the Coulter lysing agent and monomeric IgM paraprotein in the patient's plasma, creating a precipitate which was optically dense at 525 nm.

Diagnostic Errors↗
PubMed1990

Kluyveromyces as a host for heterologous gene expression: expression and secretion of prochymosin.

We have developed the yeast Kluyveromyces lactis as a host organism for the production of the milk-clotting enzyme chymosin. In contrast to Saccharomyces cerevisiae, we found that this yeast is capable of the synthesis and secretion of fully active prochymosin. Various signal sequences could be used to efficiently direct the secretion of prochymosin in Kluyveromyces, but not in S. cerevisiae. We conclude that the efficient synthetic and secretory capacity of this heterologous protein is a property of the yeast Kluyveromyces. These results have led to the development of a large scale production process for chymosin.

Amino Acid Sequence↗
PubMed1983

The BPRS in assessing symptom correlates of cerebral ventricular enlargement in acute and chronic schizophrenia.

The present study was an attempt to investigate hypotheses about the interrelationship of brain dysfunction and symptoms of schizophrenia using the Brief Psychiatric Rating Scale (BPRS) and a measure of cerebral ventricular size. The ventricular brain ratio (VBR) was correlated with admission and discharge scores on the BPRS in 46 schizophrenic patients. A significant relationship was found between VBR and discharge BPRS scores. In general, the results were partially supportive of relationships found between neuropsychological data and the BPRS in a previous study, but shed little light on the relationships between brain damage and negative and positive symptoms. Limitations of using the BPRS, as well as possible sampling variations, are discussed.

Acute Disease↗
PubMed1983

Ventricular enlargement in major depression.

Major depression accompanied by psychosis may be a separate nosological entity from nonpsychotic depression. Investigators have noted behavioral and biochemical differences in psychotic and nonpsychotic patients, as well as differences in response to treatment. A previous study using computed tomography (CT) found enlargement of the lateral cerebral ventricles in patients with manic-depressive illness with psychotic symptoms. The present study examined CT scans of patients with major affective illness that was accompanied by hallucinations, delusions, or both. The ventricles of the depressed group were significantly larger than those of a group of normal controls.

Adult↗
PubMed1977

Ribosomal RNA genes of Saccharomyces cerevisiae. I. Physical map of the repeating unit and location of the regions coding for 5 S, 5.8 S, 18 S, and 25 S ribosomal RNAs.

The organization of the ribosomal DNA repeating unit from Saccharomyces cerevisiae has been analyzed. A cloned ribosomal DNA repeating unit has been mapped with the restriction enzymes Xma 1, Kpn 1, HindIII, Xba 1, Bgl I + II, and EcoRI. The locations of the sequences which code for 5 S, 5.8 S, 18 S, and 25 S ribosomal RNAs have been determined by hybridization of the purified RNA species with restriction endonuclease generated fragments of the repeating unit. The position of the 5.8 S ribosomal DNA sequences within the repeat was also established by sequencing the DNA which codes for 83 nucleotides at the 5' end of 5.8 S ribosomal RNA. The polarity of the 35 S ribosomal RNA precursor has been established by a combination of hybridization analysis and DNA sequence determination and is 5'-18 S, 5.8 S, 25 S-3'.

DNA↗
PubMed1976

A plasmid cloning vehicle allowing regulated expression of eukaryotic DNA in bacteria.

We have constructed a plasmid cloning vehicle in which transcription of inserted heterologous DNA fragments can be regulated by a defined bacterial operator and promoter. The lambda plac 5 EcoRIDNA fragment containing the operator, promoter, and beta-galactosidase gene of the lactose operon was linked to the ColE1 derivative plasmid pSF2124, creating a plasmid designated pBGP100, pBGP100 contains one EcoRI site at the lac DNA/pSF2124 DNA junction and another at the lambda DAN/pSF2124 DNA junction. We deleted the latter EcoRI site to generate a plasmid (pBGP120) retaining a single EcoRI site at the lac DNA/nSF2124 DNA junction. To determine whether DNA introduced at the EcoRI site of pBGP120 was expressed under lactose control, we inserted the EcoRI fragment containing 28S ribosomal DNA of Xenopus laevis, creating the hybrid plasmid pBGP123. RNA-DNA hybridization of pulse-labeled RNA from cells containing pBGP123 showed that induction of the lac operon increases the percentage of labeled RNA complementary to Xenopus 28S DNA about 9-fold. This vehicle may be of use for production of eukaryotic gene products in bacteria.

Animals↗
PubMed1972

5-Bromouracil-tolerant mutants of Bacillus subtilis.

5-Bromouracil (BU)-tolerant mutants of Bacillus subtilis 23 (thy his) have been isolated. Several classes of tolerant mutants were obtained by a sequential selection procedure. The classes can be distinguished by their relative BU tolerance as well as several other phenotypic characteristics. The mutants can grow for an extended period of time in minimal medium supplemented with amino acids and BU, in which the sensitive parental strain (Bu(+)) undergoes rapid cell death. Both mutants But-1 and But-1310 have a greater rate of deoxyribonucleic acid (DNA) synthesis by a factor of two in the presence of BU than Bu(+), But-1 being somewhat faster than But-1310. The preferential incorporation of thymine to BU of But-1 is about half that of the Bu(+) strain during DNA replication in minimal medium supplemented with 10 mug of BU/ml and 1 mug of thymine/ml. It is not known at what step or steps this reduction in selectivity occurs.

Bacillus subtilis↗