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Biomedical subjects

J Price

Publications and source records attributed to J Price.

At least 253 records · Page 14Linked to original sources
PubMed1989

Intraobserver variation in Doppler ultrasound indices of placental perfusion derived from different numbers of waveforms.

Continuous-wave ultrasound is used to obtain records of Doppler-shifted frequencies from arteries. Indices using the maximum frequency envelope are usually derived from a number of selected waveforms on each record and averaged. Analysis of variance was performed on indices obtained from repeated Doppler ultrasound waveform records of uterine and umbilical perfusion in late pregnancy. Intraobserver variation was minimal when derived from six (consecutive) waveforms and was less than 10% for each index.

Blood Flow Velocity↗
PubMed1989

Oscillatory potentials of X-linked carriers of congenital stationary night blindness.

ERG oscillatory potentials (OPs) were recorded from obligate carriers of CSNB and from age-matched normal subjects. The OPs were recorded under four stimulus conditions and were analyzed in the time and frequency domains. The results, first of all, provide confirmation of the previous report that the OP amplitude is reduced in carriers. Second, the results show that, of four stimulus conditions examined, the best condition for discriminating the carriers and normal subjects was when the flash was blue and the eye was dark-adapted. Third, the results show that, in the frequency domain, optimal discrimination occurs when examining the power content of the OP at a center frequency of about 130 Hz using a 70 Hz bandwidth window. In the time domain, optimal discrimination occurs when examining the amplitude of the third peak of the response.

Electroretinography↗
PubMed1988

Differential expression of a sialoglycoprotein with an approximate molecular weight of 900,000 on metastatic human colon carcinoma cells growing in culture and in tumor tissues.

Wheat germ agglutinin (WGA)-binding cellular glycoproteins produced by HT-29 human colon carcinoma and its variant cells established from liver metastases in nude mice after intrasplenic injection were analyzed by polyacrylamide gel electrophoresis. On 5.5% polyacrylamide gels five major sialoglycoproteins (approximate Mr 115,000, 145,000, 190,000, 450,000, and 740,000) reactive with WGA were common to the parental and metastatic sublines. There was an additional component of Mr approximately 900,000 that was prominent in cells established from liver metastases. Specific removal of sialic acid from the glycoproteins eliminated WGA binding, indicating that all the WGA-binding glycoproteins including the Mr 900,000 component were sialoglycoproteins. Smith degradation following mild acid hydrolysis resulted in formation of WGA-binding carbohydrate chains on Mr 115,000, 145,000, 190,000, and 900,000 components, but not on Mr 450,000 and 740,000 components, which indicated that these two sialoglycoproteins bore different oligosaccharides from the other sialoglycoproteins. The Mr 900,000 component was more prominent with HT-29 cells growing in nude mice than those growing in vitro. WGA binding to the Mr 900,000 component of metastasis-derived HT-29 cells growing in a nude mouse was higher than that of parental cells growing in nude mice. The expression in liver metastases derived from parental as well as metastatic cells was higher than the primary tumor growing in the spleen of the same mouse, indicating that the levels of Mr 900,000 sialoglycoprotein (SGP = 900) were regulated by intrinsic and environmental factors. The influence of organ microenvironmental factors was confirmed by analyzing sialoglycoproteins of HT-29 cells growing in the liver of a nude mouse following intrahepatic injection. Analyses of human colorectal carcinoma tissues and liver metastases revealed a polydisperse WGA-reactive high-molecular-weight component similar to that seen in tumors growing in nude mice. The mean value of WGA binding to high-molecular-weight glycoproteins in the primary tumors of stage B1 patients was smaller than that of all other primary tumors. Comparison of primary tumors with liver metastases from the same patients indicated that the level of SGP-900-like high-molecular-weight glycoproteins in metastases was not always higher than those in primary tumors.

Adenocarcinoma↗
PubMed1988

Effect of adaptation and wavelength on the power spectrum of human oscillatory potentials.

Oscillatory potentials were recorded from four adult subjects under dark- and light-adapted conditions with photopically balanced red and blue flashes. The responses between 80 and 200 Hz were analyzed by means of a Fast Fourier transform program. The results show a robust change in the power--but not in the frequency composition--with the different stimulus conditions. We suggest that an analysis of the total power within this frequency band may provide a quantitative way of evaluating the duplex nature of the oscillatory potentials.

Adaptation, Physiological↗
PubMed1988

Blood pressure reactivity: pitfalls in methodology.

Two very different assumptions about the principles of blood pressure reactivity lead to quite different notions about hypertensive/normotensive behaviour. Both are referred to as the Law of Initial Value (LIV). Subsequent confusion about blood pressure reactivity vs resting level partly explains a number of inconsistencies between studies describing hypertensive behaviour. Here the validity of each assumption was tested. Young hypertensives and normotensives who had first been placed into a condition of arousal or relaxation performed a mental arithmetic task. Group behaviour and idiosyncratic paradoxical response phenomena were investigated. Results showed that the state of the subject immediately prior to the mental arithmetic task was more important in determining the reaction to that task than blood pressure category was: in an aroused subject blood pressure fell. The implications for both clinicians and researchers interested in blood pressure behaviour, in particular where stimuli have failed to elicit responses, are discussed.

Adult↗
PubMed1988

Sensitisation by mycobacteria and the effects of BCG on children attending schools in the slums of Bombay.

Quadruple skin testing with new tuberculins was used to evaluate the effects of previously administered BCG Madras in children attending schools in the slums, or living in Kopri Leprosy Colony in Bombay. There were differences between schools both in the level of sensitisation of children without BCG scars and in the effects of BCG vaccination. Results obtained at one school resembled those obtained in a previous study in Agra, where BCG was thought to be ineffective. Results from the other schools and Kopri were more like those previously reported from Ahmednagar, where BCG was considered to be much more effective. Thus within the same city groups of children of the same social status may vary widely both in their contact with mycobacteria and in their capacity to benefit from BCG vaccination.

Adolescent↗
PubMed1988

Infection surveillance in cardiac transplantation.

Infections are a major cause of morbidity and mortality in cardiac transplantation. There is little information describing screening and prospective surveillance of heart recipients. We describe a surveillance program that was used for 35 patients, which screens and follows recipients through serologic, virologic, and immunologic parameters. Pretransplantation surveillance identified four (11.4%) patients whose skin tests with purified protein derivative (PPD) were positive, one patient with giardiasis, and seven (20%) recipients who were susceptible to cytomegalovirus (CMV). Twelve (34.3%) patients had CMV infections, only one of which was primary and involved a seropositive donor. The low rate of primary infection (14%) may result from our use of CMV-negative blood products. Seven (20%) recipients who were seronegative for toxoplasmosis received seropositive hearts, and disseminated toxoplasmosis developed in one of them. Eight (22.8%) patients had asymptomatic significant increases in Epstein-Barr virus antibody titers, without evidence of lymphoma. Fifteen (42.8%) recipients had at least one herpes simplex virus reactivation. Preventive, diagnostic, and early therapeutic interventions should occur as a result of infection surveillance, thus leading to a reduced risk of infection during the period after cardiac transplantation.

Cross Infection↗
PubMed1988

The effects of follicle-stimulating hormone and cyclic guanosine 3',5'-monophosphate on cyclic adenosine 3',5'-monophosphate-phosphodiesterase and resumption of meiosis in hamster cumulus-oocyte complexes.

The effects of follicle-stimulating hormone (FSH) and cyclic guanosine 3',5'-monophosphate (cGMP) on spontaneous oocyte maturation and cyclic adenosine 3',5'-cumulus-monophosphate phosphodiesterase activity (cAMP-PDE) were evaluated by using cumulus-oocyte complexes (COCs) from proestrous hamsters. After a 2-h incubation period, FSH (10 micrograms/ml and 1 microgram/ml) reduced the percentage of maturing oocytes compared with controls. This inhibition was partially overcome when cGMP-elevating agents (8-Bromo-cGMP, atrial natriuretic factor or sodium nitroprusside) were included with FSH. After a 3-h period, incubation with FSH and cGMP-elevating agents alone increased the maturation rate above that of the controls. The accelerating effects of cGMP on the maturation rate appear to be caused by its capacity to lower cAMP levels. Combining FSH (1 microgram/ml) with sodium nitroprusside reduced cAMP levels in COCs (not oocytes) compared with groups exposed to FSH alone. FSH increased cGMP levels in COCs in a dose- and time-dependent manner. Both FSH and cGMP-elevating agents produced a dose-dependent increased cAMP-PDE activity in COCs (not oocytes) following a 2-h incubation period. Together, these results suggest that, in vivo, FSH stimulates a rise in both cAMP and cGMP in COCs. While the increase in cAMP may be the initial meiotic trigger, cGMP may serve to subsequently lower cAMP by activating cAMP-PDE and thus permit the maturational process to continue.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

Cell lineage in the rat cerebral cortex: a study using retroviral-mediated gene transfer.

We have used a retroviral vector that codes for the bacterial enzyme beta-galactosidase to study cell lineage in the rat cerebral cortex. This vector has been used to label progenitor cells in the cerebral cortices of rat embryos during the period of neurogenesis. When these embryos are allowed to develop to adulthood, the clones of cells derived from the marked progenitor cells can be identified histochemically. In this way, we can ask what are the lineage relationships between different neural cell types. From these studies, we conclude that there are two distinct types of progenitor cells in the developing cortex. One generates only grey matter astrocytes, whereas the second gives rise to neurones - both pyramidal and nonpyramidal - and to another class of cells that we have tentatively identified as glial cells of the white matter. We have also been able to address the question of how neurones are dispersed in the cortex during histogenesis. It had been previously hypothesized that clonally related neurones migrated radially to form columns in the mature cortex. However, we find that clones of neurones do not form radial columns; rather, they tend to occupy the same or neighbouring cortical laminae and to be spread over several hundreds of micrometers of cortex in the horizontal dimension. This spread occurs in both mediolateral and rostrocaudal directions.

Animals↗