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D L Zhang

Publications and source records attributed to D L Zhang.

11 recordsLinked to original sources
PubMed1992

The use of transcranial ultrasonography to predict stroke in sickle cell disease.

BACKGROUND: Stroke, especially cerebral infarction, is a major cause of morbidity and mortality in children with sickle cell disease. Primary prevention of stroke by transfusion therapy may be feasible if there is a way to identify the patients at greatest risk. Transcranial Doppler ultrasonography can measure flow velocity in the large intracranial arteries. The narrowing of these arteries, which leads to cerebral infarction, is characterized by an increased velocity of flow. METHODS: Using transcranial Doppler ultrasonography, we prospectively measured the velocity of cerebral blood flow in children and young adults being followed because of sickle cell disease. The results were classified as either normal or abnormal on the basis of the highest velocity of flow in the middle cerebral artery. Abnormal velocity was defined as a flow greater than or equal to 170 cm per second, a definition determined by post hoc analysis to maximize the predictive success of the test. The end point was a clinically apparent first cerebral infarction. RESULTS: Two hundred eighty-three transcranial ultrasound examinations were performed in 190 patients with sickle cell disease (age at entry, 3 to 18 years). After an average follow-up of 29 months, cerebral infarction was diagnosed in seven patients. In 23 patients the results of the ultrasound examinations were abnormal, and in 167 patients they were normal. The clinical and hematologic characteristics of the two groups were similar, but six of the seven strokes occurred among the 23 patients with abnormal ultrasound results (P less than 0.00001 by Fisher's exact test). In this group, the relative risk of stroke was 44 (95 percent confidence interval, 5.5 to 346). CONCLUSIONS: Transcranial ultrasonography can identify the children with sickle cell disease who are at highest risk for cerebral infarction. Periodic ultrasound examinations and the selective use of transfusion therapy could make the primary prevention of stroke an achievable goal.

Adolescent↗
PubMed1991

Studies on preparation of inactivated vaccines from cell cultures of mink enteritis virus (MEV) and their immunity.

In this paper, superhigh reproductive rate strains of MEV with titre more than HA8192x or TCID50 log10(9.7) have been achieved both by cultivation in cell lines with different susceptibility to MEV and by isolating and identifying in field by the author. The systematic tests proved that S18 and L12 strains of MEV are the best strains for vaccine preparation. In this study, the best means for the tissue cultivation of MEV and the most advanced technological process for the production and detection of serum-free cell-cultured MEV fluids with super-high HA titre in batches in large quantities have been established for the first time. Optimum conditions for MEV inactivation were determined, and safe and effective inactivated vaccines with mineral oil or Al(OH)3 gel adjuvant were successfully prepared with serum-free cell-cultured MEV fluids. Both vaccines with different adjuvants can be manufactured in batches in large quantities and have been widely used all over China since 1986. The change laws of the immune response kinetics of the MEV vaccines have been determined by the tests, and the indexes and laboratory animal models for monitoring humoral immune efficiency and immune protective rate of parvovirus vaccines have been established for the first time. The manufacturing and monitoring operation rules of the MEV vaccines with different adjuvants have been laid down by the author.

Animals↗
PubMed1989

Recording of the electrocardiogram from the sinus node and direct measurement of the sinuatrial conduction time in children.

Using a simple technique, the electrocardiogram from the sinus node, which had been previously recorded in adults, was for the first time derived successfully in 27 of 31 children (87%). The values of the sinuatrial conduction time were then precisely measured directly according to the electrocardiogram from the sinus node. The sinuatrial conduction time measured directly was significantly longer in 6 children with sick sinus syndrome (138.3 +/- 10.3 msec, mean +/- standard deviation) than in 21 normal children (66.9 +/- 14.4 msec, mean +/- standard deviation). No overlap was found between them. Furthermore, comparison was made between the children and the adults (7 cases with sick sinus syndrome, 32 cases with normal sinus nodal function). The results suggested that the electrocardiogram recorded from the sinus node may be a valuable and promising technique for the evaluation of sinus nodal function and in the accurate diagnosis of the sick sinus syndrome in children.

Adolescent↗
PubMed1989

A plant DNA-binding protein that recognizes 5-methylcytosine residues.

A novel, 5-methylcytosine-specific, DNA-binding protein, DBP-m, has been identified in nuclear extracts of peas. DBP-m specifically recognizes 5-methylcytosine residues in DNA without appreciable DNA sequence specificity, unlike a mammalian DNA-binding protein (MDBP), which recognizes 5-methylcytosine residues but only in a related family of 14-base-pair sequences.

5-Methylcytosine↗
PubMed1988

Methylated DNA-binding protein is present in various mammalian cell types.

A DNA-binding protein from human placenta, methylated DNA-binding protein (MDBP), binds to certain DNA sequences only when they contain 5-methylcytosine (m5C) residues at specific positions. We found a very similar DNA-binding activity in nuclear extracts of rat tissues, calf thymus, human embryonal carcinoma cells, HeLa cells, and mouse LTK cells. Like human placental MDBP, the analogous DNA-binding proteins from the above mammalian cell lines formed a number of different low-electrophoretic-mobility complexes with a 14-bp MDBP-specific oligonucleotide duplex. All of these complexes exhibited the same DNA methylation specificity and DNA sequence specificity. From the extracts of rat and calf tissues, oligonucleotide protein complexes formed that also had the same specificity as human placental MDBP although they had a higher electrophoretic mobility probably due to digestion by proteases in the nuclear extracts. Although MDBP activity was found in various mammalian cell types, it was not detected in extracts of cultured mosquito cells and so may be associated only with cells with vertebrate-type DNA methylation.

5-Methylcytosine↗
PubMed1988

Comparison of indirect and direct sinuatrial conduction time by synchronous sinus node electrogram.

In order to determine whether or not the estimated indirect sinuatrial conduction time represented the real sinuatrial conduction time, we recorded the synchronous sinus node electrogram, on which direct sinuatrial conduction time could be measured during constant atrial pacing, in 21 cases with normal sinus node function. The results show first that the difference between direct and indirect sinuatrial conduction time is statistically significant (P less than 0.05); the correlation of the two is poor (r = 0.29). Second, the direct sinuatrial conduction time after constant atrial pacing is significantly longer than that before constant atrial pacing, which means constant atrial pacing has resulted in obvious depression of conduction through the sinus node. Our conclusion is that estimated indirect sinuatrial conduction time does not represent real sinuatrial conduction time. The calculation formula using constant atrial pacing has been based on a major unproven assumption.

Adult↗