Z C Tian | PubMed Health

PubMed2001

[Random amplified polymorphic DNA analysis of Cryptosporidium species and strains].

OBJECTIVE: To analyse the genetic heterogeneity of 8 isolates of Cryptosporidium belonging to three species (Cryptosporiduim muris, Cryptosporiduim parvum and Cryptosporidium meleagridis) using RAPD technique. METHODS: DNA extracts of the 8 isolates were amplified by PCR using 26 out of 200 primers. The amplified products were separated by agar electrophoresis followed by staining with ethidium bromide. RESULTS: RAPD analysis revealed; 1. Obvious differences among species were found, the average genetic distance being 7.037; 2. Certain differences among different isolates of the same species were found, the average genetic distance being 5.162. CONCLUSION: RAPD could differentiate the common and respective gene fragments of the 8 isolates of Cryptosporidium.

Animals↗

PubMedDate not supplied

Reduced MR acquisition time with the CROCUS technique.

A technique to reduce magnetic resonance (MR) image acquisition time by approximately 50% is introduced. The conjugate reconstruction by off-center under-sampling (CROCUS) method samples only every other phase-encoded line in raw data space and uses the conjugate symmetry of the data to reconstruct a real image. If acquisition and image reconstruction were done in the simplest manner, this under-sampling would produce unacceptable image aliasing. However, if the phase-encoded lines are offset from the origin, the assumption of conjugate symmetry allows the image to be calculated without aliasing. Unfortunately, information from all practical MR systems contain phase-shift errors that produce deviations from conjugate symmetry. The CROCUS method incorporates a correction technique, similar to that used in other half-Fourier methods, which uses low-resolution phase-shift information obtained from a few extra lines of phase-encoded data. This paper provides a theoretical derivation of the reconstruction algorithm and correction technique and illustrates the results. Excellent image quality is obtained with no loss of spatial resolution. Image signal-to-noise ratio is reduced by a factor of approximately 1.4 because of the reduced acquisition time. When the imaging circumstances are such that a high signal level is available, CROCUS imaging can be an effective means of reducing imaging time.

Humans↗