Search PubMed⌕ Search

Biomedical subjects

J D Harvey

Publications and source records attributed to J D Harvey.

At least 37 records · Page 2Linked to original sources
PubMed1980

Laser light-scattering studies of bull spermatozoa. I. Orientational effects.

Calculations based on the known dimensions of bull spermatozoa show that the scattered light intensity is strongly dependent upon the relative orientation of the particle to the incident beam. The magnitude of this effect of apparently much greater than for other systems where motility has been investigated by dynamic light scattering. The calculations show that the scattering source can be approximated by a small spinning mirror, and consequently the greatest light intensity at the detector results from cells swimming in a direction perpendicular to the scattering vector. The calculations are in substantial agreement with photographic observations, as well as direct measurements of the scattered intensity. Previous treatments of dynamic light scattering from swimming bull spermatozoa based on point scattering models are shown to be incorrect.

Animals↗
PubMed1980

Subunit structure of the reovirus spike.

Cross-linking reovirus spike protein with the bifunctional reagent dimethyl suberimidate revealed that each spike was composed of a pentameric aggregate of polypeptide lambda 2.

Cross-Linking Reagents↗
PubMed1979

Generation time statistics of Escherichia coli B measured by synchronous culture techniques.

Synchronous cultures of Escherichia coli B were produced under various environmental conditions. Analysis of the cell number data permitted the characterization of the generation time distribution for these organisms and the estimation of the mother-daughter generation time correlation coefficients. For all growth conditions, the distribution of generation times was found to be symmetrical with a coefficienoefficient was significantly negative at doubling times between 40 and 64 min. However, the results for a culture growing in succinate medium at 37 degrees C, which had a significantly greater generation time, yielded a correlation coefficient close to zero. Within the range of temperatures studied (26 to 37 degrees C), no significant effect on the correlation coefficient was observed.

Bacteriological Techniques↗
PubMed1977

The molecular size and shape of liver glycogen.

The molecular-weight distribution of liver glycogen has been established from the analysis of sedimentation rates of fractions separated on sucrose density gradients and from the direct measurement of the diffusion coefficients of these fractions by laser-intensity-fluctuation spectroscopy. Hydrodynamic studies indicated that all fractions of glycogen of mol.wt.exceeding 25x10(6) had about 1.1 g of water per g of polysaccharide associated with them. The hydration and hydrodynamic behaviour of all fractions of mol.wt. exceeding 25x10(6) was similar, whereas smaller fractions behaved anomalously, indicating a substantially different overall structure.

Centrifugation, Density Gradient↗
PubMed1977

Hydrodynamic properties of 2-mercaptoethanol-modified glycogen.

Treatment of glycogen with 2-mercaptoethanol and iodoacetamide gives rise to a modified glycogen which resembles the original glycogen in its hydrodynamic behaviour but has a pronounced tendency to aggregate. The modified glycogen can be distinguished easily, by its diffusion coefficient, from glycogen degraded by more traditional methods of extraction. The 'fundamental' glycogen particle appears to be composed of two or three glycogen beta-particles linked by a single protein chain.

Animals↗
PubMed1974

Molecular weight of two oncornavirus genomes: derivation from particle molecular weights and RNA content.

Sedimentation analysis and intensity fluctuation spectroscopy have been used in conjunction with the Svedberg equation to determine the particle molecular weights of Rous sarcoma virus (Prague strain) and avian myeloblastosis virus (BAI strain). The molecular weights of these two viruses are (294 +/- 20) x 10(6) and (256 +/- 18) x 10(6), respectively. Values for the molecular weight of the RNA contained in each particle have been calculated as (5.58 +/- 0.5) x 10(6) and (5.88 +/- 0.5) x 10(6). Since the proportion of the viral RNA represented by 4 to 7S low-molecular-weight material is known, the molecular weight of the 60 to 70S genomes may be calculated to lie in the range (3.8 +/- 0.3 to 4.8 +/- 0.4) x 10(6) for both particles. These estimates for the molecular weight of the 60 to 70S genome are much lower than previous estimates and fall within the range of current estimates of the size of a single 35S subunit. The implications of this finding are discussed in terms of current theories for the structure of the genome of RNA tumor viruses.

Avian Leukosis Virus↗