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Biomedical subjects

H M Liu

Publications and source records attributed to H M Liu.

At least 127 records · Page 7Linked to original sources
PubMed1990

Plasma electrolyte changes after ingestion of bile extract of the grass carp (Ctenopharyngodon idellus) in rats.

Some Chinese people believe that eating the gallbladder of the grass carp (Ctenopharyngodon idellus) may improve their visual acuity. However, ingestion of grass-carp bile, in severe cases, may kill human beings and experimental animals. The cause of death after eating grass-carp bile was studied in rats. The bile acid fraction was prepared from the n-hexane-insoluble and alcohol-soluble parts of grass-carp and hog bile. The bile extract (6 ml/kg, 15%) was administrated by gastric intubation to conscious female Long-Evans rats. Ingestion of grass-carp bile extract killed all the experimental rats in 2-8 h and was associated with a decrease in blood pressure and an increase in plasma potassium, hydrogen ions, blood urea nitrogen and hematocrit. However, rats that ingested hog bile or saline showed no significant changes in the measured parameters. If the rats were fed cholestyramine-treated grass-carp bile extract, they survived without significant change in the measured parameters. This report demonstrates that a drastic increase in plasma potassium and hydrogen ions probably caused the death of the rats, and also shows that bile acid (alcohol) in grass-carp bile is related to the toxicity.

Animals↗
PubMed1989

Molecular cloning, coding nucleotides and the deduced amino acid sequence of P-450BM-1 from Bacillus megaterium.

The gene encoding barbiturate-inducible cytochrome P-450BM-1 from Bacillus megaterium ATCC 14581 has been cloned and sequenced. An open reading frame in the 1.9 kb of cloned DNA correctly predicted the NH2-terminal sequence of P-450BM-1 previously determined by protein sequencing, and, in toto, predicted a polypeptide of 410 amino acid residues with an Mr of 47,439. The sequence is most, but less than 27%, similar to that of P-450CAM from Pseudomonas putida, so that P-450BM-1 clearly belongs to a new P-450-gene family, distinct especially from that of the P-450 domain of P-450BM-3, a barbiturate-inducible single polypeptide cytochrome P-450:NADPH-P-450 reductase from the same strain of B. megaterium (Ruettinger, R.T., Wen, L.-P. and Fulco, A.J. (1989) J. Biol. Chem. 264, 10987-10995).

Amino Acid Sequence↗
PubMed1989

Immunohistochemical localization of intracellular plasma proteins in the human central nervous system.

The regional distribution of plasma protein immunoreactivity was studied in the postmortem central nervous system (CNS) of normal subjects 18 to 78 years old. Samples taken from various areas of brain and spinal cord were processed for peroxidase-antiperoxidase immunocytochemistry using polyclonal antibodies against plasma albumin, prealbumin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, IgG, transferrin, haptoglobin, hemopexin, fibrinogen, as well against the glial fibrillary acidic and S-100 proteins. Many neurons of the spinal cord, cranial nerve nuclei, pontine nuclei, cerebellar dentate nucleus, red nucleus, thalamus and hypothalamus showed strong immunostaining for albumin and moderate to strong staining for alpha 1-acid glycoprotein, IgG, transferrin, haptoglobin, as well as relatively weak immunoreactivity against other plasma proteins. Less intense staining was seen in the nucleus basalis, putamen and Purkinje cells. In contrast, most cerebral cortical neurons were negative except for a few positively stained pyramidal neurons in the hippocampus and in layers III and V of the association neocortex, although more positive pyramidal neurons were observed in the motor and sensory neocortices. Reaction products were also seen in axons of motor and sensory long tracts. These findings suggest that plasma proteins may be transported to spinal cord and brain stem neurons by peripherally projecting nerves and that a series of anterograde and retrograde transneuronal transfers are responsible for the accumulation of plasma proteins in relay nuclei and in other CNS neurons.

Adult↗
PubMed1988

In vitro nerve-growth-promoting activity of human plasma alpha 1-acid glycoprotein.

Human plasma alpha 1-acid glycoprotein or orosomucoid (OR), and its derivatives, prepared by sequential enzymatic cleavage of the carbohydrate units, were tested for their nerve-growth-promoting activities with explants of whole dorsal root ganglia from chick embryos. The results showed that the OR derivatives with terminal galactose, N-acetylglucosamine, or mannose have marked neurite-promoting activities. These preparations at a concentration of 100 micrograms/ml are equivalent to 5% fetal bovine serum (protein concentration 3,000 micrograms/ml) in their ability to elicit extensive neurite outgrowth and collateral branching. The asialo-OR, or ASOR, is the most potent form: its activity is estimated to be 20 times higher than that of transferrin and 100 times over that of fibronectin; it is approximately 1/1,500 that of NGF. The neurite-promoting activity of OR is independent of the non-neuronal cells and their products and can be blocked by a specific antiserum against OR. The mode of action of OR on the in vitro nerve growth is discussed and the pathophysiological significance of this plasma glycoprotein is considered in light of data from recent clinical and pathological studies.

Animals↗
PubMed1988

Neovasculature and blood-brain barrier in ischemic brain infarct.

The cellular events occurring in ischemic brain infarcts of 1 day to 8 weeks duration were investigated. The material consisted of 17 human postmortem brains with anemic infarcts caused by occlusive vascular diseases. Using antiserum against human plasma albumin as a marker for the breakdown of blood-brain barrier and ammoniacal silver nitrate stain to demonstrate the vasculature, the onset and distribution of the extravasated plasma protein was compared with histological changes in the blood vessels. It was observed that extravasation occurred in several separate regions of the infarct during different time periods. During the first few days, plasma proteins exudated from the vessels located at the marginal zone surrounding the infarct. This was followed by a prolonged phase of intense extravasation that coincided with the production of new capillaries originating from the blood vessels at the margin of the infarct and from pial vessels. It is postulated that the actively proliferative and migratory activities of the endothelial cells and pericytes in the neovasculature may be responsible for the extravasation which is reflected in the contrast enhancement of the infarct observed clinically during the recovery phase.

Blood-Brain Barrier↗
PubMed1988

A method for the quantitative analysis of nerve growth in vitro.

A method is described for the quantitative analysis of the nerve-growth-promoting activity of biological molecules in tissue culture. The criteria used for the evaluation of this activity is based on the neurite length as well as the total number of neurites produced by the explant of whole dorsal root ganglia from 12-d-old chick embryos. A nerve growth index (NGI) is given to each ganglion during each of a 5-d culture period. The NGI is defined as the product of average neurite length in millimeters and the total number of neurites. We report that with increasing concentrations of fetal bovine serum, there was a proportional increase in NGI due to increased neurite density while the neurite length was not greatly affected. The NGI of several proteins with known nerve growth promoting activity, namely nerve growth factor, insulin, transferrin, and fibronectin were investigated for their activity and compared with that of fetal bovine serum.

Animals↗
PubMed1988

Extravasation of plasma proteins in brain trauma.

The cellular distribution of extravasated plasma proteins in cortical contusions was studied with an immunoperoxidase method using polyclonal antibodies against human plasma albumin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, alpha 1-antitrypsin, transferrin, hemopexin, haptoglobin, fibrinogen, fibronectin and immunoglobulin G. The material consisted of 24 human autopsy brains with a primary diagnosis of cerebral contusion due to blunt trauma. The time interval between injury and death ranged between minutes and 7 years. Immediately after the trauma, a complete breakdown of the blood-brain barrier (BBB) occurred with hemorrhage and extravasation of all types of plasma proteins. This was followed by spreading of edema fluid within the extracellular space in and around the wound. Uptake of extravasated protein by glial cells began on the 3rd day followed by proliferation of reactive astrocytes whose ample cytoplasm appeared to serve as a reservior for the extravasated plasma proteins. Within the reactive astrocytes, plasma proteins and S-100 protein had a similar and diffuse distribution in the immunostained sections. The plasma proteins once incorporated into the glial cells remained unchanged for several years with little sign of degradation. It is suggested that the extravasated plasma proteins subsequent to uptake and processing by the glial cells, may serve some important physiological function in wound healing.

Adolescent↗
PubMed1988

Immunohistochemical and ultrastructural observations on Homer Wright (neuroblastic) rosettes and the "pale islands" of human cerebellar medulloblastomas.

A combined immunohistochemical and ultrastructural study of 20 cerebellar medulloblastomas has demonstrated features of early neuronal differentiation. The differentiation features are primarily encountered in the Homer Wright rosettes and in the reticulin-free "pale islands," or "follicles," of the desmoplastic variant. They consist of parallel arrays of aggregated neurite-like processes containing longitudinally oriented microtubules (immunoreactive for polyvalent antisera to tubulin and gamma-enolase, but nonreactive for a monoclonal antibody to the 150/200 kD subunits of neurofilament protein) and junctional adhesion plaques. We consider the inherent property of self-aggregation of the neurite-like processes with adhesion plaques a significant mechanism in the formation of Homer Wright rosettes. Further differentiation and elongation of these cell processes may lead to the formation of "pale islands" in the desmoplastic medulloblastoma. A meshwork of astroglial cells, coexpressing glial fibrillary acidic protein and S-100 protein immunoreactivity, forms an integral part of the "pale island." The histogenetic significance of these astrocytes and their relationship to tumor cells expressing early neuronal differentiation remains to be defined.

Cell Transformation, Neoplastic↗
PubMed1987

Bilateral symptomatic intraspinal T12-L1 synovial cysts.

A 72-year-old man presented with several months of increasing lumbar pain, sciatica, lower extremity weakness, numbness in his buttocks and posterior thighs, burning sensations in his scrotum, and urinary incontinence. Myelogram-computed tomography scan demonstrated a high grade incomplete block at the T12-L1 level due to bilateral synovial cysts and simultaneously a high grade partial block at L4-L5 due to spinal stenosis. Laminectomy of the T-12 vertebra and partial laminectomy of the L-1 vertebra with excision of both synovial cysts and laminectomies of the L-4 and L-5 vertebrae with foraminotomies resulted in a reversal of the patient's symptomatology.

Aged↗
PubMed1987

Demonstration of a keratan sulfate proteoglycan and a mannose-rich glycoconjugate in corpora amylacea of the brain by immunocytochemical and lectin-binding methods.

The aim of the present report is to call attention to the fact that corpora amylacea (CA) of the brain have similar biochemical and immunological characteristics as the connective tissue matrix. We have demonstrated that CA reacted positively toward a monoclonal antibody that specifically recognized the polysaccharide determinant on cartilage proteoglycans. Material strongly bound to concanavalin A was demonstrated in CA, blood vessel wall and cartilage and suggested high levels of mannose in these structures. These findings are in agreement with the known fact that both brain and cartilage contain keratan sulfate and high mannose glycoproteins. We propose that CA may result from accumulation of glycoconjugates normally present in the brain tissue matrix as the result of aging.

Aged↗
PubMed1987

Renal functions following hyperbaric oxygen toxicity in conscious rats.

The after-effects of renal function were studied in rats exposed to hyperbaric oxygen (HBO) at either 4.8 ATA for 60 min or 6.8 ATA until the onset of convulsions. Only the rats which suffered from HBO convulsions were found to have alterations in renal function. It was observed that 4 hr after convulsions, there was a decrease in urinary excretion of urea and creatinine, which resulted in an elevation of blood urea nitrogen (BUN) and creatinine. Clearances of inulin and p-aminohippuric acid showed a decrease in the glomerular filtration rate and effective renal blood flow 4 hr after HBO convulsions. These parameters nearly returned to normal in 24 hr after convulsions. The renal handling of a large volume of infused saline was also retarded 4 hr after HBO convulsions, but by the end of 24 hr after HBO convulsions, it was much improved. Therefore, it was concluded that the renal function was altered after HBO convulsions, but nearly recovered in 24 hr.

Animals↗
PubMed1986

The effect of swimming-stress on tail-flick latency of normal and hypophysectomized rats.

The effect of swimming-stress on pain threshold was investigated in normal and hypophysectomized male rats of Long-Evans strain. The Tail-Flick Latency (TFL) was taken for determining the algesic sensitivity to noxious heat stimulation of the tail. The present study has shown that swimming-stress could prolong the TFL to thermal tail stimulation. In 15 intact control rats, the TFL were prolonged from 2.47 +/- 0.07 (Mean +/- S.E.) to 3.81 +/- 0.21 sec. In 10 sham-operated and 10 hypophysectomized rats, the TFL were also prolonged from 3.10 +/- 0.25 to 4.37 +/- 0.35 and 3.59 +/- 0.09 to 4.50 +/- 0.13 sec respectively after a 3 min swim. Therefore, the hypophysectomy did not appear to modulate the analgesic effect induced by swimming-stress. These experimental data implied that the hypophysis may not be important in the analgesic effect induced by the swimming-stress.

Animals↗