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Biomedical subjects

D Liu

Publications and source records attributed to D Liu.

At least 685 records · Page 38Linked to original sources
PubMed1994

[Retroviral-mediated transfer of human beta-globin gene and its enhancer into MEL cells].

The present result showed that human beta-globin gene has been integrated into amphotropic packaging cell line PA317 in 5/13 clones of PA317 beta and 1/14 clone of PA317 beta E0.4. Retrovirus titers of amphotropic recombinant retrovirus ranged from 10(3) to 10(4) CFU/ml. MEL cells were transfected by supernant of PA317 beta and PA317 beta E0.4. Northern blot showed that the expression of human beta-globin gene in MEL beta E0.4 was significantly higher than MEL beta in mRNA level. This result indicated that an enhancer which comes from HS II of human LCR can increase human beta-globin gene mRNA expression in transfected MEL. However, the retrovirus titers of PA317 beta and PA317 beta E0.4 in our experiment were low. When large fragment enhancer (0.4 kb) was inserted into retrovirus vector, it could bring about the human beta-globin gene deletion in amphotropic packing cells.

Animals↗
PubMed1994

[Laser Doppler flowmetry for evaluation of nasal mucosa microcirculation].

The purpose of this study was to determine the blood flow within the human nasal mucose and whether it is changed in patients with chronic rhinitis. Using a laser Doppler flowmeter (He-Ne Laser equipment PF2 type), we measured the nasal mucosa blood flow (NMBF) in a group of healthy young subjects 108 (18-25 years) and three types of chronic rhinitis 89 (chronic rhinitis 15, allergic rhinitis 44, atrophic rhinitis 30). A Laser Doppler probe was placed on six different points of the nasal mucose membrane. The study data indicate that the average index of the NMBF of human are retentive steady and decreased obviously in three types chronic rhinitis. So it may be concluded that detection of NMBF is a useful method for evaluation of the therapy effect of chronic rhinitis.

Adolescent↗
PubMed1994

Electrophysiologic effects of total flavones of Hippophae rhamnoides L on guinea pig papillary muscles and cultured rat myocardial cells.

The effects of total flavones of Hippophae rhamnoides L (TFH) were evaluated using conventional microelectrode technic. After administration of TFH 100-200 mg.L-1, the action potential duration of 50% repolarization (APD50) was shortened both in cultured rat myocardial cells and in guinea pig papillary muscles. The slope of phase 4 of depolarization (SP4) in cultured rat myocardial cells was decreased and the contractile force (CF) in guinea pig papillary muscles was weakened. Arrhythmias evoked by strophantin G in guinea pig papillary muscles were suppressed by TFH 100 mg.L-1. These findings suggested that the influence of TFH on myocardial cells may be resulted mainly from its inhibition of Ca2+ influx and its interference with intracellular Ca2+ reservoir.

Action Potentials↗
PubMed1994

[The diagnosis and treatment of sphenoid inflammatory neoplasms and sphenoid sinus tumors].

We have analyzed the clinical data of 27 cases of sphenoid inflammatory neoplasms and sphenoid sinus tumors including inflammations (12 cases), benign tumors (10 cases) and malignant tumors (5 cases). The characteristics of sphenoid inflammatory neoplasms were compared with those of sphenoid sinus tumors. On CT scanning and magnetic resonance imaging (MRI) we found that sinusitis resulted in much less bony erosion than tumors on CT scanning and that the T2-signal intensity on MRI increased much more in sinusitis than in tumors. We have discussed the indications of various operative approaches and suggested that the approach of external ethmoidectomy is a method of choice.

Adolescent↗
PubMed1994

[Carotid body tumor: diagnosis and surgical treatment].

Carotid body tumors are rarely encountered and can present a difficult surgical problem. During the period of June 1988 to November 1992, 8 patients were operated on for carotid body tumors at PLA General Hospital. Details of the surgery, morbidity and outcome of these patients are presented. Our experience suggests that: 1) The presence of a pulsatile neck mass located in the region of carotid triangle, vertically fixed and laterally mobile, should raise the suspicion of a carotid body tumor; 2) Color Doppler flow imaging has a role to play in the diagnosis of carotid body tumor; 3) DSA is very important for a number of reasons, especially for the use of concomitant embolization; 4) Management of these tumours is primarily surgical; 5) The decision whether to resect the carotid artery or not can only be made intra-operatively based on status of the patient and tumor, there might be 4 surgical options open to the operators.

Adult↗
PubMed1994

[General expression of linear pharmacokinetic model].

This paper reports the integration of pharmacokinetic models of mammilla, chain, physiology, intravenous injection, intravenous infusion and extravascular administration into a single mathematical model. We have given a general mathematical treatment of this model and a common expression of drug concentration-time relationship. The model fits in any single or multiple dosing linear pharmacokinetic process involving in physiology, nonphysiology, and any compartmental administration and excretion.

Drug Administration Routes↗
PubMed1994

[Plasma renin activity (PRA), angiotensin II (AII), atrial natriuretic peptide (ANP) and AII/ANP ratio in severely burned patients].

Plasma renin activity (PRA), angiotensin II (AII), atrial natriuretic peptide (ANP) and AII/ANP were determined by radioimmunoassay in samples of blood from 59 burn patients. The results demonstrated that PRA, AII, ANP, AII/ANP increased significantly postburn. The increased level of AII/ANP correlated positively with the extent of burn injury as well as the severity of postburn renal dysfunction suggesting that the imbalance of AII and ANP played an important role in the pathogenesis of postburn renal damage.

Acute Kidney Injury↗
PubMed1994

[In vitro cultivation of the exoerythrocytic stage of Plasmodium vivax (southern China isolate)].

An in vitro culture system for the exoerythrocytic (EE) stage of Plasmodium vivax was first developed in our laboratory in China. Anopheles stephensi mosquitoes were infected by membrane feeding with heparinized blood from a volunteer. After 14-18 days, the mosquito salivary glands were aseptically dissected in culture medium and ground in a tissue grinder to form sporozoite suspension. Sporozoites were counted and added to the cultures of monolayer hepatoma cells at the number of 4.9 x 10(4)-1.3 x 10(5) per cover glass. Sometimes, 8-10 pairs of infected gland were added directly to the cultured cells. On day 7, EE schizonts of P. vivax were found in cultures. In addition, normal erythrocytes (type o) were added to the cultures on day 10 at a concentration of 10(8) per dish. Fourteen days later, erythrocytes in culture supernatant were collected and thin blood films were made. Numerous intra-erythrocytic P. vivax parasites were identified on the films after Giemsa staining. Most intra-erythrocytic forms were rings and early large trophozoites. Schuffer's dots were present in many of the infected cells which were pale and obviously enlarged. These results indicated that the in vitro hepatic cycle of P. vivax was established.

Animals↗
PubMed1993

Retinal ganglion cells within the foveola of New World (Saimiri sciureus) and Old World (Macaca fascicularis) monkeys.

The morphology and distribution of retinal ganglion cells within the foveola of New World (Saimiri sciureus) and Old World (Macaca fascicularis) monkeys labeled as a result of horseradish peroxidase injections into the dorsal lateral geniculate nucleus were studied. The results indicate that monkey's foveola normally contains significant numbers of retinal ganglion cells. Most of these project ipsilaterally. Cells within the foveola are larger than other cells in monkey central retina; their dendritic fields are up to 50 times larger in area than those of cells in the foveal slope. The dendritic fields of the ganglion cells within the foveola cover at least 70-100% of its area. Among ganglion cells within the foveola (as in most ganglion cells), there was a strong tendency for the axon and dendritic tree to arise from opposite poles of the soma. The axon-dendrite axes of ganglion cells within the foveola did not show a consistent pattern. In contrast, the axes of ganglion cells in the transition zone between the foveola and the foveal slope were directed tangentially to the circumference of the fovea. The dendritic coverage of the foveola by retinal ganglion cells suggests functional significance and provides a possible neural basis for 2-3 degrees of bilateral representation of the fovea within the central visual pathways. Alternatively, or in addition, these cells may be "remnants of foveation" and provide insight into the developmental processes that mediate the development of the fovea.

Animals↗
PubMed1993

Measurement and relationship of subarachnoid pressure of the optic nerve to intracranial pressures in fresh cadavers.

We performed a study on six fresh cadavers to measure the subarachnoid pressure of the optic nerve and to determine its relationship to intracranial pressure. A lateral orbitotomy via a coronal flap was used to expose the optic nerve. Various intracranial pressures were achieved by saline infusion through a ventriculostomy. The subarachnoid pressure of the optic nerve was measured at 5 and at 25 mm posterior to the globe under conditions of the created intracranial pressure. The effectiveness of optic nerve sheath decompression performed by two standardized surgical techniques was determined experimentally and by theoretic calculations; the role of the bulbous portion of the optic nerve was assessed experimentally. Measurements of the subarachnoid pressure of the optic nerve showed interindividual variation and a linear relationship with the intracranial pressure. Surgical decompression through a 3 x 5-mm window was more effective than were three linear 5-mm incisions. The bulbous portion of the optic nerve was found to have an important role in cerebrospinal fluid circulation.

Adult↗
PubMed1993

Studies of the dimerization and domain structure of gamma delta resolvase.

gamma delta Resolvase is a site-specific recombinase (20.5 kDa) that catalyzes the resolution of a negatively supercoiled plasmid to a catenated pair of circular DNA products (Reed, R. R. (1981) Cell 25, 713-719). Cross-linking experiments and size exclusion high pressure liquid chromatography analysis of isolated fragments corresponding to specific proteolytic cleavage indicate that the intact enzyme and the large fragment exist in a monomer-dimer equilibrium (KDdimer = 8.0 microM, intact enzyme; KDdimer = 0.1 microM, large fragment) and that the small fragment, which displays DNA binding specificity, is a monomer. Dimerization is further supported by line width comparisons in one-dimensional NMR spectra and determinations of the correlation time of the protein. The one-dimensional proton NMR spectra spectroscopy spectra indicate that the overall structure of the two isolated fragments is highly similar to the structure present in the domains of the intact enzyme. The rotational correlation time of resolvase, determined from relaxation data obtained from each domain, indicates that the small domain has a limited degree of additional motion with respect to the large domain of the enzyme. The monomer-dimer equilibrium and small domain mobility may assist in the binding of resolvase to palindromic-type sites with variable spacers and in subunit exchange during catalysis.

Chromatography, High Pressure Liquid↗
PubMed1993

A simplified technique of orbital decompression for severe retrobulbar hemorrhage.

Severe retrobulbar hemorrhage may occur as a complication of a retrobulbar injection or from blunt or sharp injury to the orbit during an orbital or periorbital operation. When the patient with a severe retrobulbar hemorrhage does not respond to intermittent ocular massage, or paracentesis, or a lateral canthotomy, prompt orbital decompression becomes necessary. A simple and effective surgical technique that is applicable in such urgent situations was used in this study. The procedure does not entail waiting for computed tomography or the availability of an orbital surgeon and requires only minimal local anesthetics. A small mosquito clamp is inserted into the orbit through a small opening in the inferior fornix. The clamp is advanced into the orbit along the medial orbital floor until a depth of about 20 mm is reached. Pressure is applied to the clamp to break the orbital floor and maxillary sinus mucosa, and to decompress the orbit. I successfully used this technique on five patients in the past five years.

Adult↗
PubMed1993

Role of H5 domain in determining pore diameter and ion permeation through cyclic nucleotide-gated channels.

Ion permeation through membrane channels is thought to be governed by a narrow region of the channel pore termed the selectivity filter, which has been proposed to discriminate among ions by both specific binding and molecular sieving, as determined by pore diameter. Recent evidence suggests that a conserved domain (known as H5, P or SS1-SS2) in voltage-gated potassium, sodium and calcium channels contributes to the lining of the pore. Here we investigate whether the H5 domain determines pore diameter and examine the role of pore diameter in controlling ion permeation. These studies rely on differences in single channel conductance, ion selectivity and apparent pore diameter between cyclic nucleotide-gated channels cloned from bovine retina and catfish olfactory neurons. Using chimaeric retinal-olfactory channels, we find that the H5 domain determines these differences in permeation properties, providing structural evidence that the cyclic nucleotide-gated channels are indeed members of the voltage-gated channel family. Moreover, these results show directly that the H5 domain helps form the selectivity filter and that molecular sieving is important in controlling ion permeation.

Amino Acid Sequence↗
PubMed1993

Methylprednisolone reduces excitatory amino acid release following experimental spinal cord injury.

Administration of methylprednisolone within several hours after injury to the spinal cord has been shown to reduce subsequent impairment in humans and experimental animals. Secondary damage following initial trauma is probably caused in part by the toxicity of released excitatory amino acids. We demonstrate here that methylprednisolone reduces the release of excitatory amino acids following experimental spinal cord injury in rats.

Amino Acids↗