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Biomedical subjects

J Yu

Publications and source records attributed to J Yu.

At least 793 records · Page 44Linked to original sources
PubMed1991

Transneuronal degeneration of thalamic neurons following deafferentation: quantitative studies using [3H]thymidine autoradiography.

Transneuronal degeneration of thalamic neurons following partial deafferentation was studied using [3H]thymidine autoradiography. Timed-pregnant female Sprague-Dawley rats received systemic injections of [3H]thymidine on embryonic day (E) 13, 14 and/or 15. On the day of birth, pups were anesthetized by hypothermia and subjected to unilateral enucleation, unilateral removal of the inferior colliculus or sham lesion. Animals were sacrificed on postnatal day 10 or 30 and the brains processed for autoradiography. Material from sham-lesioned animals demonstrates that neurons destined for the dorsal lateral geniculate nucleus (LGd) undergo final mitoses on E13, 14 and 15. Neurons in the ventral medial geniculate nucleus (MGv) undergo final mitoses on E13 and 14. Thirty days following neonatal unilateral eye removal, the contralateral LGd displays a loss of approximately 30-35% of [3H]thymidine labeled neurons. Neonatal unilateral removal of the inferior colliculus results in a loss of approximately 30-40% of labeled neurons in MGv. For both LGd and MGv, shorter survival times reveal less severe cell loss. Late generated (E15) LGd neurons show less severe loss following enucleation than do earlier generated neurons. These results document the degree of cell loss in sensory thalamic nuclei following deafferentation and demonstrate that [3H]thymidine autoradiography provides a useful quantitative method for assessing anterograde transneuronal cell loss in targeted populations of neurons in the developing central nervous system.

Afferent Pathways↗
PubMed1991

Primary auditory cortex in the rat: transient expression of acetylcholinesterase activity in developing geniculocortical projections.

A characteristic pattern of acetylcholinesterase (AChE) activity is expressed transiently in primary auditory cortex (cortical area 41) of developing laboratory rats during early postnatal life. This AChE activity occurs as a dense plexus in cortical layer IV and the deep part of layer III. This transient band of AChE activity is first detected by histochemical techniques on postnatal day (P) 3, reaches peak intensity at approximately P8-10, and declines to form the adult pattern by P23. The ventral nucleus of the medial geniculate body of the thalamus also displays prominent, and transient, staining for AChE. This intense staining for AChE, found within neuronal somata and neuropil, is detected at the time of birth, reaches peak intensity around P8, and declines to adult levels by P16. The areal and laminar patterns of the transient band of AChE activity in temporal cortex correspond to the patterns of anterograde transneuronal labeling of geniculocortical terminals following injection of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the inferior colliculus. Placement of lesions that include the medial geniculate nucleus or the geniculocortical axons results in a marked decrease in AChE staining in thalamorecipient layers of auditory cortex. Placement of lesions that include the medial globus pallidus reduce AChE staining of some axons in temporal cortex of developing rats, but the dense band of AChE in layers III and IV remains. Placement of lesions in the inferior colliculus in newborn animals results in marked decrease in AChE staining in cells of the ipsilateral ventral medial geniculate nucleus and in ipsilateral auditory cortex of developing pups. These data indicate that transiently expressed AChE activity is characteristic of geniculocortical neurons, including their somata in the medial geniculate body and their terminal axons in primary auditory cortex. This AChE activity is expressed early in postnatal development, probably during the time when thalamocortical axons are proliferating in cortical layer IV and forming synaptic contacts with cortical neurons.

Acetylcholinesterase↗
PubMed1991

Blood interactions with novel polyurethaneurea hydrogels.

The influence on blood of polyurethaneurea hydrogels in vitro was investigated based on poly(ethylene oxide). A hydrogel was compared with the regenerated cellulose membrane Cuprophan in terms of complement activation, as determined by measurement of C3a concentration. The hydrogel induced less complement activation and the presence of poly(ethylene oxide) is likely to be beneficial to platelet reactivity. The ability to vary the polymer composition and the solubility of the polymers in organic solvents makes the polyurethaneurea hydrogels strong candidates for composite biomaterials.

Biocompatible Materials↗
PubMed1991

Response of slowly adapting pulmonary stretch receptors to reduced lung compliance.

We examined the steady-state response of slowly adapting pulmonary stretch receptors (SAPSRs) to reduced lung compliance in open-chest cats with lungs ventilated at eupneic rate and tidal volume (VT) and with a positive end-expiratory pressure (PEEP) of 3-4 cmH2O. Transient removal of PEEP decreased compliance by approximately 30% and increased transpulmonary pressure (Ptp) by 1-2.5 cmH2O. Reduction of compliance significantly decreased SAPSR discharge in deflation and caused a small increase in discharge at the peak of inflation; it had little effect on discharge averaged over the ventilatory cycle. Increasing VT to produce a comparable increase in Ptp significantly increased peak discharge. Thus unlike rapidly adapting receptors, whose discharge is increased more effectively by reduced compliance than by increased VT, SAPSRs are stimulated by increased VT but not by reduced compliance. We speculate that the most consistent effect of reduced compliance on SAPSRs (the decrease in deflation discharge) was due to the decreased time constant for deflation in the stiffer lung. This alteration in firing may contribute to the tachypnea evoked as the lungs become stiffer.

Animals↗
PubMed1991

Intracellular pH measurement with fluorescent dye in canine basilar arteries.

The intracellular pH (pHi) of basilar artery rings was determined with 2',7'-bis-(carboxyethyl)-5,(6)-carboxyfluorescein (BCECF) by measuring the ratio of emitted (540 nm) fluorescence intensities (FI) at excitation wavelengths of 500 and 440 nm. There was a dye loss from the rings in 90 min (39.3 +/- 3.6%, p less than 0.001). We found that the ratio of fluorescence intensities does not adequately correct for dye loss; hence, we derived a method to correct for dye loss during pHi determinations. Calibration curves of the ratio versus pHi were constructed for the artery rings. The slope and intercept of the calibration curves depended on FI440. Linear regression lines for the slope and intercept versus FI440 were: [formula; see text] In solutions with different pH and different concentrations of free BCECF, the slope of the ratio versus pH of the solution was steeper at high concentrations of BCECF. Thus, pHi was calculated from a calibration curve in which the slope and intercept were determined from FI440 with the above formula. The corrected pHi was 7.37 +/- 0.05 (n = 25) at pHo 7.4 and 37 degrees C.

Amiloride↗
PubMed1991

Relationship between blood radioimmunoreactive beta-endorphin and hand skin temperature during the electro-acupuncture induction of ovulation.

Thirteen cycles of anovulation menstruation in 11 cases were treated with Electro-Acupuncture (EA) ovulation induction. In 6 of these cycles which showed ovulation, the hand skin temperature (HST) of these patients was increased after EA treatment. In the other 7 cycles ovulation was not induced. There were no regular changes in HST of 5 normal subjects. The level of radioimmunoreactive beta-endorphin (r beta-E) fluctuated, and returned to the preacupunctural level in 30 min. after withdrawal of needles in normal subjects. After EA, the level of blood r beta-E in cycles with ovulation declined or maintained the range of normal subjects. But the level of blood r beta-E in cycles in which the induction failed to cause ovulation was kept higher that that of normal. (P less than 0.05). There was a negative correlation in the decrease of blood r beta-E and increase of HST after EA (r = 0.677, P less than 0.01). EA is able to regulate the function of the hypothalamic-pituitary-ovarian axis. Since a good response is usually accompanied with the increase of HST, monitoring HST may provide a rough but simple method for predicting the curative effect of EA. The role of r beta-E in the mechanism of EA ovulation induction was discussed.

Anovulation↗
PubMed1991

Histopathological and ultrastructural changes of lichen sclerosus et atrophicus on the vulva.

Studies of 82 skin specimens from 81 cases of lichen sclerosus et atrophicus (LSA) are reported. Typical LSA pathological changes showed atrophy of the epidermis, hydropic degeneration at the basal layer, and homogenization of the collagen fibers in the superficial dermis with inflammatory cell infiltration underneath. Ultrastructural changes showed intercellular spaces enlarged, particularly near basal cells. Some mitochondria were swollen and rough endoplasmic reticula were enlarged. Some basement membranes were thinner, collagen fibers of varying diameters were arranged in irregular shapes and the fine structures had become unclear and had sometimes even disappeared.

Adolescent↗
PubMed1991

Inhibition of bone marrow immature B lymphocytes from zinc deficient mice by methionine enkephalin.

Bone marrow cells (BMC) from Zn deficient mice were used to measure the anti-TNP plaque forming cell (PFC) response in the presence of methionine enkephalin (Met-Enk). The results demonstrated that the PFC response of BMC was suppressed by Met-Enk. In the case of Zn deficient group, the inhibitions were up to 51% compared to 27% for the control and became higher as the increasing concentration of Met-Enk. It seems that the sensitivity to Met-Enk was related to degree of Zn deficiency. These findings suggest that Zn may interfere with the role of Met-Enk on BMC.

Animals↗
PubMed1991

Calcium channels in smooth muscle.

The molecular and biophysical characterization of Ca2+ channels in smooth muscle has lagged behind that in cardiac and skeletal muscles. This is caused by the difficulties in isolating viable cells and applying electrophysiological techniques to smooth muscle cells. The heterogeneity of smooth muscle cells from different organs also adds to the complexity. In spite of these problems there has been an increasing number of reports on Ca2+ channels in smooth muscle. This review provides an overview of this area. As in skeletal muscles, L (long-acting) and T (transient) voltage-dependent Ca2+ channels are found in smooth muscle; the former is better characterized. L channel is regulated by voltage, Ca2+, cyclic nucleotides, and protein kinase C. Ca2+ also influxes through receptor-operated channels that are voltage insensitive. The receptor-operated and T channels are insensitive to dihydropyridine. Clinically, Ca2+ blockers are extensively used for diseases of the cardiovascular system, with more limited use in the gastrointestinal tract. Further understanding of the properties of Ca2+ channels could lead to development of selective Ca2+ channel blockers for the gastrointestinal tract.

Calcium Channel Blockers↗
PubMed1991

Ascites and pleural effusions associated with endometriosis.

We report a case of ascites and bilateral pleural effusions associated with an endometrioma in a 26-year-old woman of Chinese descent. She had a right salpingo-oophorectomy and partial omentectomy performed, and she received leuprolide acetate depot injections after the operation. We believe this is the first description of use of a GnRH agonist to treat this rare condition.

Adult↗
PubMed1991

[Effect of shen-qian gu-jing granule on fibrin degradation products in serum and menstrual fluid of patients with menorrhagia].

Shen-Qian Gu-Jing granule was used in the treatment of the menorrhagia in 72 cases including idiopathic menorrhagia 28, uterine myoma 29, endometriosis 7, intrauterine device 5, postpartum and post induced abortion 3 cases. The amount of menstrual blood loss (MBL) and the fibrin degradation products (FDP) level in menstrual fluid and peripheral blood were measured before and after treatment. 87.5% of all cases showed a significant decrease in MBL (P less than 0.05). The local FDP level significantly decreased parallel to effectiveness of MBL. The results suggested that the function of this Chinese herbs complex in menorrhagia was related to the regulation of FDP level.

Adult↗