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Biomedical subjects

K M Liu

Publications and source records attributed to K M Liu.

At least 55 records · Page 3Linked to original sources
PubMed1990

Robotic arm use by very young motorically disabled children.

This paper reports on a study carried out to determine if very young children would interact with a small computer-controlled robotic arm. Six disabled and three normal children were used in the study. All children were less than 38 months in age. The arm was trained to carry out movements on activation of a single switch by the child. Fifty percent of the disabled children and 100% of the normal children did interact with the arm and use it as a tool to obtain objects out of reach. Possible relationships between the use of the arm and developmental levels in various areas are discussed.

Child, Preschool↗
PubMed1990

Effect of unilateral vagotomy on capsaicin-induced neurogenic inflammation in the trachea of rats.

This study reports the effect of unilateral vagotomy on neurogenic inflammation in the trachea. Neurogenic inflammation was produced in the trachea of vagotomized rats by a venous injection of capsaicin, the pungent ingredient of red pepper. Monastral blue was used as tracer dye to label the affected blood vessels. Vagus nerves and tracheal tissues were processed for light and electron microscopy. The damaged right vagus nerve was found to have degenerated. However, unilateral vagotomy did not completely block neurogenic inflammation in the trachea ipsilaterally and contralaterally, as shown in the whole mount preparations. Microscopic observations of tracheal tissue sections showed that neurogenic inflammation did not evenly occur on both sides of the trachea. The possible reason for this is discussed.

Animals↗
PubMed1989

Discordant results obtained on testing sera from immunocompromised patients for cytomegalovirus IgG by enzyme-linked immunosorbent assay and radioimmunoassay.

The investigation of sera from immunocompromised patients for antibody to CMV by ELISA, RIA, immunofluorescence (IF) and complement-fixation (CF) revealed discrepancies that reflected differences in test specificity rather than sensitivity and suggested that for the long-term serological follow-up of such patients it would be advisable not to rely on only a single assay procedure.

Adult↗
PubMed1989

[Studies on the antiarrhythmic effects of leaves of Dendropanax chevalieri (Vig.) Merr. et Chun].

Aqueous extract of the leaves of Dendropanax chevalieri (DC), administrated orally, showed prominent protective effect against arrhythmias induced by iv aconitine CaCl2 (120mg/kg) in mice and BaCl2 (4mg/kg) in rats. In anesthetized rabbits, the duration of arrhythmia elicited by ivAdr 75 micrograms/kg was markedly shortened by iv DC 0.4g/kg. It might also obviously delay the onset of arrhythmias and cardiac electricity disappearance evoked by ouabain perfusing consistently into isolated guinea-pig hearts.

Animals↗
PubMed1989

Morphological and morphometric studies of early myelination in the cervical dorsal funiculus of the newborn mouse spinal cord.

The early myelination of the dorsal funiculus at the level of the 4th cervical spinal cord was ultrastructurally studied in the one-day-old mouse. It was found that the fibers were mainly unmyelinated. However, some early myelinated fibers were scattered among unmyelinated fibers. In the initial stage of the myelination, the axon was partially contracted by a piece of cytoplasmic process of the oligodendroglial cell. The two lips of the oligodendroglial process then extended and converged, enwrapping the axon completely and forming the first contact point. With the anchorage of that contact point, the two lips of the process became elongated and enfolded by each other, and produced the internal and external tongues of the future myelin sheath. More contact points were formed at a regular interval by the regional fusion of the two external surface layers of the opposed cytoplasmic membranes of adjacent tongue processes. With the advanced bidirectional spiralization of the two tongue processes, many contact points were found between the adjacent lamellae of the concentrically arranged oligodendroglial process; simultaneously, the cleft between the neighboring contact points disappeared and formed the initial sites of the intraperiod line. During the early myelination, one single axon ensheathed concentrically by two different oligodendroglial processes as well as several axons enwrapped by a continuous spiral myelin sheath of one oligodendroglial cell were frequently observed. The cross-sectional areas of unmyelinated axons varied from 0.01 to 0.2 micron 2, with a median of 0.07 micron 2; whereas, that of promyelinated axons ranged from 0.09 to 1.4 micron 2, with a median at 0.61 micron 2. These data support the suggestion that the axon calibre is a critical factor for the initiation of central myelination.

Animals↗
PubMed1987

Preliminary studies on antigenic variation of poliovirus using neutralizing monoclonal antibodies.

Cross-neutralization assays were done using 85 strains of poliovirus type 1 with five groups of monoclonal antibodies. These strains were classified into 10 subgroups which had marked differences in antigenicity. Subgroups P1-2 (28%) and P1-5 (43%) were dominant and have been epidemic in China in recent years. These two subgroups were antigenically different from the Sabin-1 strain, but according to their responses to one group of monoclonal antibodies they had antigenic epitopes in common with the Mahoney and Brunhilde strains. Similarly, 91 strains of type 3 poliovirus were classified into six subgroups with another five groups of monoclonal antibodies. The results showed that strain P3/Yunnan/2/84, which was isolated from cases of poliomyelitis in a local epidemic in the Yunnan province of China in 1984, and strain P3/Finland/23127/84, which was isolated in Finland in 1984, were both antigenically different from the Sabin-3 strain and the reference virulent strain.

Animals↗
PubMed1986

The effect of staining on the immunoreactivity of nitrocellulose bound proteins.

It was found that Coomassie blue staining of proteins electroblotted onto nitrocellulose resulted in a significant decrease in subsequent immunoreactivity, relative to unstained proteins. This was not uniform, and resulted in distortion of the pattern detected by immunoreaction as well as an overall decrease in sensitivity. Staining with amido black resulted in no such alteration. Additionally, it was observed that amido black is completely leached from the nitrocellulose strip during immunoreaction, whereas no leaching is apparent with Coomassie blue. This may contribute to the observed effect of staining on immunoreactivity.

Antigen-Antibody Reactions↗
PubMed1986

The lipofuscin in neuroglial cells of the optic nerve of Formosan rock-monkey (Macaca cyclopis).

The ultrastructure of lipofuscin granules in neuroglial cells of the optic nerve of the Formosan Rock-Monkey was investigated by electron microscopy. In the cytoplasm of astroglial cells, numerous irregular lipofuscin granules were characterized by the presence of large lipid droplets, small electron-dense pigment granules, and some lamellar structures. The lipofuscin granules of the oligodendroglial cells were composed largely of dense, coarse pigment granules, multilinear structures, and a few small lipid droplets. The lipofuscin granules in microglial cells were characterized by numerous lipid droplets in various sizes, small electron-dense pigment granules, and prominent lamellar structures. It was reported that the lipofuscin granules are wear-and-tear materials and products from the cells in lower functional activity. However, our observations suggest that the presence of lipofuscin granules in the neuroglial cells of the optic nerve is likely a characteristic product of active phagocytosis.

Animals↗
PubMed1985

Ultrastructural sequence of myelin breakdown during Wallerian degeneration in the rat optic nerve.

Adult albino rats were subjected to unilateral surgical removal of the eyeball. After survival times of 7-140 days, the numerical response of the neuroglial cells, and the progressive disintegration of the myelin sheaths in the optic nerves, were studied qualitatively and quantitatively in electron-microscopic montages. The distribution density of microglia and astroglia in degenerating optic nerve increased to peaks after 35 and 56 days respectively, whereas, the oligodendroglia gradually decreased. During the early stage of degeneration, microglial cells appeared and invaded the sheath at the intraperiod line, peeling off the outer lamellae, which were then engulfed by phagocytosis. Within the microglia, myelin sheath fragments were surrounded by a membrane curled to form a myelin ring. In the intermediate stage of degeneration, the paired electron-dense lines of the ring, made up of myelin basic protein, decomposed and formed a homogeneous or heterogeneous osmiophilic layered structure, the myelin body, which, in the final stages, disintegrated and transformed into globoid lipid droplets and needle shaped cholesterol crystals.

Animals↗
PubMed1984

Inhibition of oxidative degradation of hyaluronic acid by uric acid.

It has been postulated that glycosaminoglycans in the trabeculum have an influence on aqueous humor drainage. Ascorbate reduces the viscosity of hyaluronic acid, and also increases outflow facility. Our recent observation of high urate concentrations in some glaucomatous eyes led us to study the influence of urate on oxidative degradation of hyaluronic acid by ascorbate. The viscosity of rooster comb hyaluronic acid was reduced slowly by ascorbate. Cupric sulfate accelerated ascorbate oxidation and also enhanced hyaluronic acid degradation. Urate inhibited ascorbate oxidation and prevented the copper catalyzed oxidative degradation of rooster comb hyaluronic acid. The range of urate concentrations used in this study was within the range of urate concentrations observed in glaucomatous eyes. The partially purified umbilical cord hyaluronic acid had lower viscosity than rooster comb hyaluronic acid, and rapidly degraded in the presence of ascorbate. The ascorbate effect on umbilical cord hyaluronic acid was partially prevented by urate.

Animals↗
PubMed1984

Difference between the thyroid gland of normal and hypomyelinated jimpy mice--a light microscopic study.

A light microscopic quantitative analysis was performed on normal and jimpy male mice for studying the difference between the structures of the thyroid glands of the two animals. The results of this analysis showed that the thyroid gland of the normal mice consisted of numerous homogenous round follicles with cuboidal follicular cells, separated by thin interlobular and interfollicular connective tissue and a few adipose tissue. The thyroid gland of jimpy mice consisted of a few, small follicles surrounded by columnar follicular cells and intraepithelial capillaries, separated by thick connective tissue and abundant adipose tissue. The number of thyroid follicles are significantly less in the jimpy mice than in the normal mice. Another striking difference is that almost every follicular cell surrounding the follicular lumen of jimpy mice is accompanied by an intraepithelial capillary. In addition, the ratio of the number of intraepithelial capillaries to the number of the thyroid follicular cells are significantly higher in the jimpy mice than in the normal mice. The S-follicles or ultimobranchial cysts of the thyroid gland are well developed in the jimpy mice. The parafollicular cells are normal in appearance. Morphological evidence suggested that the thyroid follicular cells of the jimpy mice are very active in the transport, synthesis and release of thyroglobulin, and secretion of thyroid hormones. But owing to the significantly decreased number of thyroid follicles, the inadequate secretion of the thyroid hormones result in the hypothyroidism and the hypomyelination of the jimpy mice.

Animals↗
PubMed1984

Neuroglia of the adult rat optic nerve in the course of wallerian degeneration.

The neurological reactions in Wallerian degeneration have been studied by electron microscopy in the optic nerve of adult albino rats from 7 to 120 days after unilateral enucleation. Reactive astrocytes contained abundant dense bodies, numerous microtubules and hyperplastic glial filaments. These astrocytes also assisted phagocytosis of degenerated myelin sheaths and in glial scar formation. Oligodendrocytes disconnected their cytoplasmic extensions, which were phagocytosed by microglial cells and astrocytes, by increased production of lysosomes. Microglial cells consisted of crinkled, long, rough endoplasmic reticula, several highly-active Golgi complexes, laminar inclusions and globoid lipid droplets. Microglia engulfed and lysed the disintegrated axons and myelin sheaths.

Animals↗