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Biomedical subjects

I Chen

Publications and source records attributed to I Chen.

70 records · Page 4Linked to original sources
PubMed1980

An electron microscopic study of the baroreceptors in the internal carotid artery of the spontaneously hypertensive rat.

The carotid baroreceptor field of normotensive (NTR) and spontaneously hypertensive rats (SHR) examined in this study extends for about 0.5 mm along the length and about 1/3 to 1/2 of the circumference of the wall of the internal carotid artery opposite to the carotid body. The vascular wall of the baroreceptor field exhibits neither a marked dilation to form a carotid sinus nor histological differences in the intima and media compared to other parts of the carotid artery. Histologically the adventitia of the baroreceptor field is characterized by (1) an increased thickness and by less well developed elastic lamellae in comparison with other parts of the arterial wall, (2) a profuse blood and nerve supply, and (3) a richness of cellular elements. The presumptive baroreceptor terminals are localized in the inner 1/3 of the adventitia and display local enlargements that appear to show preferential association with the cell body or processes of the Schwann cell but not with other components of the adventitia. the enlargements are characterized by an accumulation of very densely packed mitochondria, and glycogen particles. No morphological alterations were noted in the baroreceptor terminals of SHR except for proliferated basal laminae that invest the terminals. Our work does not support the concept that resetting of the baroreceptors is due to degeneration of the terminals.

Animals↗
PubMed1980

Brain aging in normotensive and hypertensive strains of rats. II. Ultrastructural changes in neurons and glia.

A variety of age-related changes occur in the structure of neurons in the cerebral cortex of Wistar-Kyoto and spontaneously hypertensive rats. The most marked alteration associated with increasing age was the deposition of lipofuscin pigment, primarily at the bases of apical dendrites of pyramidal neurons. While no strain-related differences in the amount of lipofuscin pigment were observed in the youngest (3 months) and in the aged (22-27 months) groups of rats, it appeared that hypertensive rats had larger pigment deposits at 12 months of age. At the ultrastructural level, neurons of the aged brains exhibited numerous nuclear invaginations and filamentous nuclear inclusions, increased amounts of Golgi complex and two types of cytoplasmic inclusions. The number of degenerative structures in the neuropil (membranous whorls, dystrophic axons and alterations in myelin sheaths) was also apparently increased in the aged brains. Neurofibrillary tangles were observed in dendritic processes of a 27-month-old Wistar-Kyoto rat. Glial cells accumulated distinctive pigment granules by which the three types of glia could be identified.

Age Factors↗
PubMed1980

Effects of aging on the structural and permeability characteristics of cerebrovasculature in normotensive and hypertensive strains of rats.

This study demonstrates that markedly different patterns of age-related changes in blood pressure and body weight occur among normotensive Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats and spontaneously hypertensive rats (SHR). In addition, a variety of age-related structural alterations occurred in the walls of arterioles, capillaries, and venules of the frontal cortex. These changes include: (1) an increase in the thickness of the vascular wall by deposits of collagen and basal lamina which, in some cases, extended into the surrounding neuropil; (2) the presence of a flocculent material in the adventitia of intracerebral arterioles; (3) vesicular inclusions in perivascular macrophages, pericytes and smooth muscle cells which were labelled with i.v. administered horseradish peroxidase (HRP); (4) fragmentation of smooth muscle cells; and (5) accumulation of lipofuscin-like pigments in perivascular glial processes. The hypertensive rats exhibited these changes, but they were more advanced and more widely distributed throughout the cerebral cortex. The aged hypertensive rats occasionally had large bundles of 10 nm diameter, intermediate filaments in the endothelial cells. Whereas no change in blood-brain barrier permeability to HRP was observed in the aged normotensive rats, all age groups of the hypertensive rats exhibited increased permeability to HRP in the initial segment of penetrating arterioles in laminae I and II of the cerebral cortex.

Age Factors↗
PubMed1977

Stability of the intra-epithelial component of the blood-testis barrier in epinephrine-induced testicular degeneration in Syrian hamsters.

Adult male Syrian hamsters were given daily intraperitoneal injections of epinephrine (1.0 mg/kg) and papaverine, a vasodilator, (60 mg/kg) for a period of ten days. After the treatment period, lanthanum and horseradish peroxidase tracer studies were used to examine the intra-epithelial component of the blood-testis barrier. Degenerating tubules often exhibited only Sertoli cells and spermatogonia, or Sertoli cells alone. Sertoli cell processes in the degenerating tubules often arched out from the main cell body to make contact with other Sertoli cell processes, forming a series of vacuole-like spaces in the germinal epithelium, adluminal to the Sertoli-Sertoli junctions. At the site of contact between these arching Sertoli cell processes one to eight tight junctions had formed with hexagonal arrays of Sertoli cell cytoplasmic filaments located immediately adjacent to these junctions. Cisternae of the Sertoli cell endoplasmic reticulum lay deep to the layer of cytoplasmic filaments. It appeared that these junctions had originated after the expulsion of the germinal elements of the seminiferous epithelium. Penetration of the tracers in the degenerating seminiferous tubules was prevented by what appeared to be normal Sertoli-Sertoli junctions located between apposed Sertoli cells, adluminal to the remaining spermatogonia when these resisted degeneration, or just adluminal to the basal lamina in those tubules in which spermatogonia were absent.

Animals↗
PubMed1976

Oral calcium supplementation in premature and asphyxiated meonates.

Biochemical and hormonal effects of oral calcium supplementation in premature and asphyxiated neonates during the first few days of life are described. Eight pairs of infants were matched for gestational age and one-minute Apgar score. One member of each pair served as a control and the other was given supplemental oral calcium (75 mg/kg/24 hr) beginning at 12 and ending at 72 hours of age. The supplemental infants had significantly higher serum calcium values both during the time of supplementation and for 36 hours after supplementation was stopped. The oral calcium supplements had no significant effect on serum concentrations of phosphate, magnesium, 25-hydroxy-vitamin D3, or parathyroid hormone, The incidence of hypocalcemia after 12 hours of age was 0 in eight supplemented infants and three in eight control infants. In patients at risk for hypocalcemia, prospective use of oral calcium supplements during the period when there is inadequate calcium intake from feedings may prevent hypocalcemia, appears to be without deleterious effect on measurable chemical and hormonal factors important in calcium homeostasis, and results in maintenance of higher serum calcium levels after supplementation has been discontinued.

Administration, Oral↗
PubMed1975

[Effect of d,l-alpha-methyl-3, 5, 3, 5-tetraiodothyronine ethylester hydrochloride (CG-635) on experimental hypercholesterolemia and atherosclerosis in rabbits (author's transl)].

To develop the prophylactics and the curatives for atherosclerosis, thyroxine derivative, CG-635, was assayed for its physiological activities in experimental atherosclerosis in rabbits fed with cholesterol. It was found that CG-635 possessed serum TC/TP value lowering activity (total cholesterol/total phospholipid) in normal and cholesterol fed rabbits for 3 weeks, and prevented the elevation of the value of cholesterol fed rabbits by daily injection for 7 weeks. CG-635 also depressed the hyperlipemia induced by cholesterol feeding, and its inhibitory effect was shown to be more marked on the increase of cholesterol than triglyceride, phospholipid and free fatty acid in serum. CG-635 did not, however, influence GOT, GPT and G-6-Pase activities in serum with increased cholesterol intake. From the histological findings it was proved that this compound prevented to a high degree the occurrence of atherosclerosis and fatty liver of cholesterol fed rabbits. Furthermore, it was recognized that thyroid hormone and the thyroid simulating hormone-like activities of CG-635 were much weaker than thyroxine, except for the action in the lipid metabolism.

Acetonitriles↗
PubMed1975

Parathyroid function in infants of diabetic mothers.

Serum parathyroid hormone and total and ionized Ca, Mg, and P levels were determined serially from birth to 96 hr of age in 28 infants of diabetic mothers (IDM, 15 Class A, 13 Class B, C, D) and their respective mothers at the time of delivery. In spite of marked decreases in concentrations of serum total and ionized Ca from birth to 24 to 48 hr, there was an insignificant increase in serum PTH values over this period in infants of insulin-dependent mothers. Infants of Class A diabetic mothers had an equivocal PTH response. Nineteen term control infants were similarly examined and had a significant increase in serum PTH postnatally. Relatively higher values of serum ionized Ca at birth in IDM were followed by greater decreases in ionized Ca from birth to 24-48 hr of age, and by decreased neonatal parathyroid function. The data support functional hypoparathyroidism as a basis for the hypocalcemia and hyperphosphatemia of IDM. It is speculated that increased concentrations of serum ionized Ca in utero and suppression of activity in the fetal parathyroid glands may be a cause for the functional hypoparathyroidism.

Blood↗
PubMedDate not supplied

Effects of somatostatin and a somatostatin agonist on diet-induced pancreatitis in mice.

We examined the effects of somatostatin-14 and the potent somatostatin agonist (N-acetyl-[Des(Ala1,Gly2),p-Cl-Phe6,D-Trp8]-somatostatin amide) on choline deficient, ethionine enriched diet (CDED)-induced acute pancreatitis in mice. Serum amylase determinations were performed, and specimens from the pancreas were examined by light and electron microscopy. No significant beneficial effects of somatostatin or its agonist were found in this model of acute pancreatitis.

Acute Disease↗
PubMedDate not supplied

Drug-like annotation and duplicate analysis of a 23-supplier chemical database totalling 2.7 million compounds.

We have implemented five drug-like filters, based on 1D and 2D molecular descriptors, and applied them to characterize the drug-like properties of commercially available chemical compounds. In addition to previously published filters (Lipinski and Veber), we implemented a filter for medicinal chemistry tractability based on lists of chemical features drawn up by a panel of medicinal chemists. A filter based on the modeling of aqueous solubility (>1 microM) was derived in-house, as well as another based on the modeling of Caco-2 passive membrane permeability (>10 nm/s). A library of 2.7 million compounds was collated from the 23 compound suppliers and analyzed with these filters, highlighting a tendency toward highly lipophilic compounds. The library contains 1.6 M unique structures, of which 37% (607,223) passed all five drug-like filters. None of the 23 suppliers provides all the members of the drug-like subset, emphasizing the benefit of considering compounds from various compound suppliers as a source of diversity for drug discovery.

Journal Article↗
PubMedDate not supplied

Cryptococcal osteomyelitis. Report of a case with aspiration biopsy of a humeral lesion with radiologic features of malignancy.

BACKGROUND: Osteomyelitis due to Cryptococcus neoformans typically exhibits lytic lesions on radiographs. Extensive periosteal reaction is an uncommon feature. CASE: A 68-year-old man presented with pain and swelling in the left elbow. Radiologic studies exhibited a lytic humeral lesion with extensive periosteal reaction, interpreted as a malignant neoplasm. Fine needle aspiration biopsy (FNA) revealed abundant cryptococcal organisms. CONCLUSION: Cryptococcus is an uncommon cause of lytic osseous lesions that may mimic malignant neoplasms. Extensive periosteal reaction may support a radiologic diagnosis of primary osseous malignancy in rare cases. FNA with examination of Diff-Quik-stained slides may be employed for distinguishing cryptococcal osteomyelitis from malignant tumors and for prompt identification of the organisms.

Aged↗