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Biomedical subjects

D Y Chen

Publications and source records attributed to D Y Chen.

At least 109 records · Page 6Linked to original sources
PubMed1985

Imbalance of hemispheric functions in the major psychoses: a study of handedness in the People's Republic of China.

A study of hand preference and eye dominance in schizophrenia, manic-depressive psychosis, and normal controls was carried out in the People's Republic of China. An excess of sinistrality was found in both men and women schizophrenics, but not in manic-depressive patients. Both the manic-depressive and schizophrenic psychoses are characterized by a significant excess of left eye dominance and by an increasing divergence between eye and hand dominance when compared to the controls. The major published studies investigating hand preference in psychopathology are reviewed, and possible interpretations of the conflicting findings are suggested.

Adolescent↗
PubMed1985

Development of cortical polarity in mouse eggs: involvement of the meiotic apparatus.

Experiments were carried out to determine the origin of cortical polarity in mouse eggs and its possible relation to the meiotic apparatus. Cortices of mature eggs overlying the meiotic apparatus (microvillus-free area) were distinguished by an absence of microvilli and a thickened layer of actin. In contrast, the surfaces of immature oocytes were covered entirely with a dense population of microvilli and were subtended by a uniform layer of actin. When induced to undergo maturation, meiotic spindles formed in the center of immature oocytes and then moved peripherally. Coincident with the cortical localization of the meiotic spindle was the formation of a microvillus-free area, i.e., a loss of microvilli and a thickening of the actin layer associated with this region of the egg cortex. If immature oocytes were incubated in cytochalasin B, meiotic spindles formed; however, they failed to move peripherally and microvillus-free areas did not develop. Oocytes incubated in colchicine did not form meiotic spindles, although the chromosomes condensed and became localized to cortices where microvillus-free areas developed. Cytochalasin B-treated mature eggs maintained intact meiotic spindles and exhibited a disappearance of microvillus-free areas and a reduction in cortical actin. The chromosomes of mature eggs treated with colchicine remained associated with microvillus-free areas despite the disappearance of meiotic spindles. Occasionally, colchicine-treated eggs possessed more than one cortically located mass of chromosomes, each of which was associated with a microvillus-free area. These observations indicate that mechanisms involving the movement of the meiotic spindle to the oocyte cortex and development and maintenance of cortical polarity are cytochalasin B sensitive. Commensurate with the localization of meiotic chromosomes to the egg cortex is the reorganization of cortical actin and the formation of a microvillus-free area.

Animals↗
PubMed1984

The frequency of major psychiatric disorder in Chinese inpatients.

The authors applied DSM-III criteria to 268 consecutive Chinese inpatients. Nearly a quarter had affective disorder, a third had schizophrenia, and, except for one patient, none had alcoholism or drug abuse. The authors discuss the factors influencing hospitalization in China.

Adult↗
PubMed1984

Development of surface polarity in mouse eggs.

Investigations were carried out to determine what effects components of the cytoskeletal system and meiotic spindle have on the development and maintenance of surface polarity in mouse ova. The surface of the mature egg possessed numerous microvilli except for a region (microvillus-free area) adjacent to the meiotic spindle. In contrast, the surface of the immature oocyte was covered uniformly with a dense population of microvilli. When cultured in vitro immature oocytes spontaneously underwent maturation; a meiotic spindle formed in the center of the ovum which then moved to the cortex. Coincident with the cortical localization of the meiotic spindle was the formation of a microvillus-free area and subjacent layer of microfilaments. A microvillus-free area did not form when meiotic maturation was inhibited with dibutyryl cyclic AMP or chloroquine. If immature oocytes were incubated in cytochalasin B a meiotic spindle developed, but it did not become localized to the egg cortex and a microvillus-free area failed to form. Oocytes incubated in colchicine underwent germinal vesicle breakdown and chromosome condensation, a meiotic spindle did not form but the chromosomes became localized to the ovum cortex where a microvillus-free area developed. These results and observations of mature ova treated with cytochalasin B or colchicine indicate that mechanisms involving the movement of the meiotic spindle to the oocyte cortex and development and maintenance of surface polarity are cytochalasin B sensitive. Cortical localization of meiotic chromosomes brings about the formation of a microvillus-free area.

Animals↗
PubMed1983

A cytochemical study of nuclear changes in fertilized hamster eggs.

Nucleoprotein changes during male and female pronuclear development have been examined in fertilized hamster eggs utilizing the ammoniacal silver reaction (ASR) at the light and ultrastructural levels of observation. Prior to its incorporation, the paternally derived chromatin was heavily laden with ASR product. Immediately upon gamete fusion the sperm nucleus underwent a dramatic increase in staining, suggesting an augmentation in the availability of reactive sites already present in the sperm nucleus or an accumulation of "new" reactive sites from the egg cytoplasm. With subsequent transformations of the sperm nucleus into a male pronucleus, there was a progressive reduction in ASR product associated with the paternal chromatin. Concomitantly, the condensed maternal chromosomes remaining in the zygote after the conclusion of meiosis dispersed and developed into a female pronucleus; these changes were accompanied by a progressive decrease in ASR staining. At the conclusion of pronuclear development, the morphologically similar male and female pronuclei were diffusely stained with the ASR. The increase in ASR staining of the sperm nucleus immediately following gamete fusion demonstrates a major effect of the egg cytoplasm on the paternal chromatin that, heretofore, has not been recognized. This augmentation and the following decrease in ASR staining may reflect changes in nucleoproteins during pronuclear development. Differences in nuclear staining are discussed in light of previous studies of nucleoprotein transitions at fertilization.

Animals↗
PubMed1983

Sperm nuclear dispersion coordinate with meiotic maturation in fertilized Spisula solidissima eggs.

Investigations were carried out with fertilized Spisula solidissima eggs, in which changes in incorporated sperm nuclei were determined by measurement of the diameter of dispersing paternal chromatin. Results of such an analysis demonstrated that sperm nuclear dispersion does not proceed at a constant rate and consists of four phases (1-4), coordinate with major changes in the status of the maternal chromatin. (1) The first phase was a short lag period prior to germinal vesicle breakdown in which the size of the sperm nucleus increased only slightly. (2) This was followed by a rapid dispersion of the sperm nucleus coordinate with germinal vesicle breakdown. With the development of the first meiotic spindle, sperm chromatin dispersion slowed dramatically; this phase (3) lasted until the completion of the meiotic divisions at which time the sperm chromatin underwent a second rapid increase in size (4) that was correlated with development of the female pronucleus. When zygotes were treated with agents that inhibited germinal vesicle breakdown (verapamil, sodium-free seawater, and chloroquine), sperm nuclear dispersion did not occur. Evidence is presented indicating that nucleocytoplasmic interactions coincident with germinal vesicle breakdown induce sperm nuclear dispersion in Spisula zygotes.

Animals↗
PubMed1981

Studies on mechanism of action of luteinizing releasing hormone (LH-RH) in ovulation of fish--intracellular distribution of LH-RH-A in pituitary gonadotrophs as revealed by electron-microscopic autoradiography.

The results of competitive bending experiment and the electron-microscopic autoradiographic studies show that the peptide hormone, LH-RH-A (a nonapeptide), could be internalized into the gonadotrophs of the pituitary gland of the mud-carp (Cirrhrinus molitorella). It is demonstrated that the labeled peptide, 125I-LH-RH-A, is internalized not only into the cytoplasm, but also into the nucleus, apparently via the nuclear pores. It is, therefore, suggested that the peptide hormone might act directly on the genome either in the form of a hormone-receptor complex or of a single molecule.

Animals↗
PubMedDate not supplied

First pass MRA of the abdomen: ultrafast, non-breath-hold time-of-flight imaging using Gd-DTPA bolus.

The authors describe a new fast imaging sequence that can produce projection angiograms of the abdominal vessels at a rate of 2 to 3 frames per second. The result is a versatile imaging technique that can track the arrival of a bolus of contrast in major vessels. With very fast data acquisition, gross patient motion is not a problem, and routine vascular projection studies may be performed without the need for breath-holding. This method is compatible with later high-resolution three-dimensional gradient echo studies using contrast agents and may, in fact, be used as an accurate timing protocol to gauge the arrival time of contrast in various segments of the abdominal vessels. Compared with echo planar imaging, this method has the advantages of avoiding susceptibility artifacts and depicting retroperitoneum and other abdominal fat-containing landmarks and does not require extensive hardware modifications for a clinical system.

Abdomen↗
PubMedDate not supplied

Determination of gradient magnetic field-induced acoustic noise associated with the use of echo planar and three-dimensional, fast spin echo techniques.

The purpose of this study was to assess gradient magnetic-field-induced acoustic noise levels associated with the use of echo planar imaging (EPI) and three-dimensional fast spin echo (3D-FSE) pulse sequences. Acoustic noise measurements were obtained from two different high field-strength MR systems (1.5 T, Siemens and General Electric Co.) under ambient noise conditions and the use of EPI and 3D-FSE pulse sequences. Parameters were selected to produce "worst case" acoustic noise levels. Acoustic noise recordings were made at the entrance, the center, and at the exit of the magnet bores with a specially designed microphone that was unperturbed by electromagnetic fields. The highest ambient noise levels (A-weighted scale) were 67 dB (Siemens: the same values were recorded at the center and at the exit) and 78 dB (General Electric Co.; recorded at the exit). The highest acoustic noise levels recorded during activation of the gradient magnetic fields were 114 dB (Siemens) and 115 dB (General Electric Co.) and those occurred at the centers of the MR systems with the use of the EPI technique. Gradient magnetic fields associated with the use of EPI and 3D-FSE techniques produced acoustic noise levels that were within permissible levels recommended by federal guidelines.

Echo-Planar Imaging↗
PubMedDate not supplied

Solid phase radionuclide esophageal transit in mixed connective tissue disease.

Esophageal motility was studied in 24 patients with mixed connective tissue disease (MCTD) and 20 control subjects by the solid phase radionuclide esophageal transit study. A computer routine modified from Klein and Russel was used. Total mean transit time, regional mean transit time, residual fraction after first swallow, and retrograde index increased significantly in MCTD patients compared with normal control subjects. An abnormal total mean transit time occurred in 84% (20 of 24) of the patients with MCTD. Our results confirmed that delayed esophageal transit is common in patients with MCTD.

Adolescent↗