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Biomedical subjects

M Liu

Publications and source records attributed to M Liu.

At least 595 records · Page 33Linked to original sources
PubMed1992

Stimulation of fetal rat lung cell proliferation in vitro by mechanical stretch.

On the basis of in vivo animal studies and on experiments of nature, it has been suggested that fetal breathing movements are essential for normal lung growth in utero. To study this hypothesis in vitro, we examined the effect of mechanical stretch on proliferation of fetal rat lung cells maintained in organotypic culture to provide a three-dimensional matrix. Initial studies demonstrated that stretch-mediated effects on cell division and DNA synthesis in such cultures were influenced by cell inoculation density, fetal calf serum concentration, and by the amplitude, frequency, periodicity, and duration of the applied stretch. After a 48-h exposure to an intermittent stretch pattern (5% elongation, 60 stretches/min for 15 min of each hour), cell number increased 10% (P less than 0.05), cell doubling time was reduced from 71 to 55 h (P less than 0.05), [3H]thymidine incorporation into DNA increased 61% (P less than 0.01), and the [3H]thymidine-labeling index increased 2.8-fold (P less than 0.001) compared with nonstretched controls. This effect did not appear to be mediated by prostaglandins or leukotrienes because the prostaglandin synthase inhibitors ibuprofen (2.5-50 microM) or BW 755C (5 microM), leukotriene biosynthesis inhibitors BW 755C (5 microM) or MK-886 (0.3 microM), and leukotriene D4 receptor antagonist MK-571 (0.3 microM) did not block stretch-mediated effects. We conclude that mechanical forces act directly to stimulate fetal rat lung cell growth and that these results are compatible with a significant role for fetal breathing in normal fetal lung growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Immunohistochemical study of transforming growth factor-alpha in human lung cancers.

The expression of transforming growth factor-alpha (TGF alpha) was assessed by immunohistochemical staining in 52 human lung tumor samples. All of the 8 small cell lung cancers were negative whereas all of the 18 adenocarcinomas and 23 of the 26 squamous cell carcinomas showed positive immunoreaction to TGF alpha. Distribution of TGF alpha stainings in the squamous cell carcinomas was weaker and more heterogeneous as compared to the adenocarcinomas. Ultrastructural localization of TGF alpha in the squamous cell lung carcinomas by indirect immunogold staining revealed that TGF alpha is present in the cytoplasm as well as the cell membrane but not in the nucleus. This suggests that the lung cancer cells are not only the producer of TGF alpha, but also the target cells of the TGF alpha action. The expression of TGF alpha in lung tumors may be useful diagnostically in differentiating small cell lung cancer from non-small cell lung cancer and may also be important in the study of the biological properties of primary lung cancers.

Adenocarcinoma↗
PubMed1992

[Serum apolipoprotein E levels in 238 healthy adults and 161 hyperlipidemic subjects in Chengdu area].

The serum apoE levels in 238 healthy adults in Chengdu are aware determined by radioimmunodiffusion (RID) assay. The average apoE level was 3.98 +/- 0.98 mg/dl (chi +/- s). The result was basically identical with other reports. There is no difference in sex, and the level has a tendency to increase with age. One hundred and sixty-one hyperlipidemic subjects (including types IIa, IIb, IV and V were compared with the normals. Their serum apoE levels increased by different percentages depending on the type of hyperlipidemia. The percentage of increasing was especially higher in types V and IIb. The content of apoE in serum positively correlated with serum triglyceride (r = 0.65, P < 0.01) and with serum total cholesterol (r = 0.50, P < 0.01).

Adult↗
PubMed1992

[Clinicopathological analysis of 20 cases of giant cell granuloma of the jaw].

The pathological features of 20 cases of giant cell granuloma and 12 cases of giant cell tumor of the jaw were compared. Specimens of 8 cases of giant cell granuloma and 5 cases of giant cell tumor were stained with Wilder's reticular fiber stain and trichromic stain. The results showed that reticular fibers and collagenous fibers were more abundant and more focal in distribution in giant cell granulomas than in those of giant cell tumors. It is concluded that the two staining methods adopted are helpful in the differential diagnosis between these two kinds of diseases.

Adolescent↗
PubMed1992

[Management of liver trauma in adults: the results of selective nonoperative management and operative treatment].

The liver trauma is still one of the major injury in thoracoabdominal trauma, with increasing numbers and incidence in Taiwan. There is a trend toward a more conservative approach in the treatment of liver trauma. Nonoperative management for the stable patients with blunt liver trauma has been advocated in literature recently. In Veterans General Hospital-Taipei, forty-five patients with liver trauma have been admitted to Emergency Department after accident in past four years. Eighty-three percent of the trauma mechanism was blunt injury, and seventeen percent penetrating. There were ten patients selected as nonoperative management, and eight of them succeeded without operation. Retrospective analyzing various factors including age, trauma score, revised trauma score, injury severity score, amount of hemoperitoneum, blood loss and transfusion, morbidity and hospitalization, there are no statistic significances between nonoperative and operative groups, except that nonoperative group are less amount of blood transfusion. We suggest that the decision to treat the patient without laparotomy is not based on the degree of hemoperitoneum or the grade of liver injury, but rather on the stability of the patient. And further evaluation is needed.

Adolescent↗
PubMed1992

[The analgesic effect of red nucleus and preliminary research on its mechanism].

The spontaneous discharges of neurons in red nucleus (RN) of rats have been recorded with microelectrode. The discharge frequency of most RN neurons was changed by nociceptive electrical stimulation of nervi peronaeus communis or nervi tibialis or by nociceptive mechanical stimulation of tail or hind leg. The electrical activities of the somatic sensory neurons in the nucleus ventralis posterolateralis (VPL) of thalamus and of the visceral sensory neurons in the nucleus anterior and nucleus parafascicularis of thalamus have been recorded. According to the form of response to the peripheral nociceptive stimulation the neurons concerned could be divided into three types: pain-excited, pain-inhibited and pain-nonrelated. Electrical stimulating RN could change the spontaneous discharge frequency of somatic pain-related neurons of VPL and visceral pain-related neurons of nucleus anterior and nucleus parafascicularis, and could inhibit their response to somatic and visceral nociceptive stimulation respectively, but did not have influence on the activity of most pain-nonrelated neurons in VPL. The effects of electrical stimulating RN and microinjecting Ach into RN on the same pain-related neuron in VPL were similar. The experimental results show that RN can receive the somatic afferent impulses, that the excited RN can inhibit the transmission of somatic and visceral nociceptive impulses into the thalamus, and that the analgesic effect of RN is concerned with Ach.

Animals↗
PubMed1992

[Neuropsychological and behavioral status of children with congenital heart diseases].

39 children patients with acyanoid ventricular septal defect or atrial septal defect who received cardiac operation, were compared with a age and sex matched normal control group on a battery of neuro-psychological tests, intelligence tests and children behavioral checklist. Subject were examined prior to cardiac operation and 6 months after the operation. 12 of 39 children received postoperation tests. Among them, 8 were in younger children group (5 to 8 years old), 4 were in elder children group (9 to 14 years old). Results are: 1. Neuropsychological development status: (1) Full IQ(FIQ), Verbal IQ(VIQ), and Performance IQ(PIQ) of the group with heart diseases were lower than those of normal controls, and there were significant differences. (2) In cardiac patients significant impairments were found on some scores of the Halstead-Reitan Battery in comparison with the normal control group. These findings imply that patients before cardiac operation had generalized impairments in neuropsychological function. (3) Significantly more behavioral problems especially the so called externalizing and internalizing behavioral problems, were found in cardiac patients than the controls. 2. Comparison of the pre and post operative scores were made: Both groups (cardiac patients and controls) showed significant improvements in VIQ, PIQ, FIQ and most of H-R subtests scores 6 months later. But the improvements following surgery were attributed to practice effects.

Adolescent↗
PubMed1992

[A histochemical study of saikosaponins].

The root of Bupleurum chinese and B.scorzonerifolium was examined histochemically in order to clarify the distribution of saikosaponins in various tissues and parts of the root. By means of qualitative and quantitative analyses, saikosaponins, the bioactive principles in the root, were found to be abundant in the cortex outside the cambium and very little in the xylem of the root. It was also found that the thinner root hairs had the highest contents of saikosaponins, but decreased towards the thicker root head.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

[Synthesis and antitumor activity of substituted benzaldehyde/cinnamicaldehyde selenosemicarbazones].

According to drug combination principle 26 substituted benzaldehyde/cinnamicaldehyde semicarbazones were synthesized. Twelve of which were not found in literature. The structures of the title compounds were confirmed by elemental and IR, UV, 1HNMR and MS analyses. Thirteen compounds were screened in vivo against Ehrlich ascites tumor cells. Four compounds (VIIf, VIIg, VIIh, VIIm) showed strong antitumor activity. The percent increase in life span were between 46.1%-91.1%. 3-Methoxy-4-hydroxy and 3-methoxy-4-acetyloxy-cinnamicaldehyde selenosemicarbazones showed stronger activity and less toxicity with increase of life span of 76.5% (300 mg/kg) and 91.1% (60 mg/kg), respectively. They were worthy to be studied further.

Acrolein↗
PubMed1992

Effects of CO2 laser irradiation on pulpal blood flow.

CO2 laser may be beneficially applied to teeth in preventive and restorative dentistry, but its physiopathologic effects on the dental pulp have not been reported. To address the dynamic pulpal changes induced by CO2 laser the purpose of this study was to examine such changes in pulpal microcirculation. The enamel surfaces of 4 cat canines were irradiated by CO2 laser beam, delivered by either a handpiece or microslad with a focal spot diameter of 0.21mm and 0.33mm, respectively. Exposure powers of 2.6-20 W were used for durations of 0.05-0.2 sec, resulting in energy density range of 304-1440 J/cm2. Non-invasive measurement of pulpal blood flow (PBF) by a laser Doppler flowmeter was maintained continuously before and following CO2 laser irradiation. CO2 laser irradiation resulted in an immediate increase in PBF, which subsided after 2-3 min. Large pulps responded with a significantly higher PBF increase than small pulps. These results confirm that CO2 laser irradiation of the tooth surface has a thermal effect on the pulp, which is moderated by the insulating capability of dentin. It appears that the associated thermal damage is not extensive when laser exposure parameters are such as used herein.

Animals↗
PubMed1992

Effects of selected inflammatory mediators on blood flow and vascular permeability in the dental pulp.

One of the major events involving inflammatory processes is the alteration of microcirculatory hemodynamics by inflammatory mediators released from tissue components. Using modern macrocirculatory techniques, 15 mu radioisotope labeled microspheres, 133Xe washout, laser Doppler flowmetry and double isotopes, 125 and 131I-albumin, and microcirculatory methods, intravital fluorescence microscopy with FITC labeled dextran, we have examined the effects of selected mediators, e.g. 5-hydroxytryptamine (5-HT), prostaglandin E2 (PG-E2), bradykinin (BK), substance P (SP), calcitonin gene related peptide (CGRP) and histamine on blood flow and vascular permeability in the pulp of experimental animals. Surprisingly, SP and CGRP caused weak albumin leakage in the pulp, while the opposite is true in high compliance tissues, such as muscles, suggesting that the vessels in a low compliance environment, such as the pulp, may not be as permeable in response to selected mediators. Intraarterial injection of 5-HT caused a strong vasoconstriction which was mediated by 5-HT1p receptor subtype. The pulpal 5-HT receptor subtype was identified by immunocytochemistry, receptor autoradiography and functional investigations. Intravital fluorescence microscopy observations of the rat incisor preparation showed that histamine, BK and PGE2 increased permeability, whereas isoproteranol caused partial inhibition of the BK-induced increase. In an induced pulpal inflammation model using plaque extract, blood flow increased over 40% in the moderately inflamed pulp, which demonstrated severe vasodilation and polymorpholeukocyte accumulation. In the partially necrotic pulp, blood flow decreased nearly 35%. Results of this study clearly show that there is a high structural/functional correlation in pulpal microcirculation in inflammation. As demonstrated in this presentation, the effects of inflammatory mediators on pulpal microcirculatory hemodynamics are complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The effects of capsaicin on pulpal blood flow.

One of the initial events in pulpal inflammation has been characterized as neurogenic inflammation: the release of neuropeptides following excitation of sensory C-fibers by noxious stimuli which alters microcirculatory parameters, that is, vasodilation and plasma extravasation. Thus, the purpose of the study was to investigate the effect of capsaicin on pulpal blood flow (PBF) with the aim of understanding neurogenic inflammation in the dental pulp by characterizing the response of the pulpal vasculature to repeated applications of various concentrations of capsaicin. Experiments were performed on canine teeth of cats anesthetized with sodium pentobarbital. PBF was measured by the laser Doppler flowmeter following the application of capsaicin into the dentinal cavities of the canine teeth. The increases of PBF to capsaicin were 31.8 +/- 6.3% (n = 6) and 54.2 +/- 6.2% (n = 9), for 1 microM and 100 microM capsaicin, respectively. The increase of PBF peaked at about 50 sec after the capsaicin placement and the PBF returned to control level within 20 min following capsaicin removal. Four repeated applications of 1 microM capsaicin caused a small change in the peak PBF amplitude. In contrast, a second application of 100 microM capsaicin caused a significantly smaller increase of PBF than the first application (26.8 +/- 6.4% vs. 54.2 +/- 6.2%). Results of the present study show that local application of capsaicin caused the increase of PBF and that repeated capsaicin stimulations inhibited PBF responses. Smaller PBF increases in response to high concentrations of capsaicin also suggested the depletion of vasoactive substances, e.g. substance P, from the sensory nerve terminals, which appears to be dose-dependent. The PBF response to capsaicin suggests that neurogenic inflammation in the dental pulp involves capsaicin-sensitive nerve endings.

Animals↗
PubMed1992

Functional alterations in pulpal microcirculation in response to various dental procedures and materials.

Using the quantitative 15 microns microsphere injection method, the effects of several restorative procedures on pulpal microcirculation in dog canine teeth were investigated. Pulpal blood flow (PBF) decreased steadily as the remaining dentin thickness (RD) became smaller with crown preparation without water spray. One hour after the preparation wit 1/3 RD (approximately 1 mm) PBF was reduced to 10% of the control, indicating that dry deep preparation has a deleterious effect on PBF. A careful preparation to an RD of 1 mm under copious water spray had a negligible effect on PBF. Dry preparation to an RD of more than 50%, on the other hand, caused a significant increase in blood flow through shunt vessels, AVAs and "U"-turn loops as determined with the 9 microns and 15 microns microspheres. These shunt vessel activities were especially prominent in the apical portion of the pulp, suggesting that the activation of the shunt vessels may be one of the compensatory mechanisms of the pulp in response to inflammation. In rat incisor teeth observed by intravital microscope, shunt vessels opened up as the incisor tips were drilled. Impression procedures after tooth preparation with water spray using the copper band with wax caused severe flow fluctuation as compared to rubber base material impression. In anesthetics, the use of epinephrine was found to be the single most important factor affecting pulp circulation. Whether it is by infiltration or mandibular block, the use of epinephrine containing anesthetic caused a severe reduction in PBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

In situ testing of CO2 laser on dental pulp function: effects on microcirculation.

The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

Animals↗