Biomedical subjects

S Q Liu

Publications and source records attributed to S Q Liu.

At least 109 records · Page 6Linked to original sources

PubMed1989

Relationship between hypertension, hypertrophy, and opening angle of zero-stress state of arteries following aortic constriction.

Examination of changes occurring in the zero-stress state of an organ provides a way to study cellular growth in the organ due to change of physical stresses. The zero-stress state of the aorta is not a tube. It is a sector with an opening angle that varies with the location on the aorta and changes with cellular remodeling. Blood vessel remodeling can be induced by imposing a constriction on the abdominal aorta by a metal clip (aortic banding), which causes an increase of blood pressure, hypertrophy of the aortic wall, and large change of opening angle. The correlation of the opening angle with the blood vessel wall thickness and blood pressure changes in rat's aorta due to aortic banding is presented in this report. The opening angle changes daily following the aortic banding. Blood pressure rises in vessels of the upper body, but that in the lower body decreases at first and then rises to an asymptotic value. Blood vessel wall thickness increases in rough proportion to blood pressure. Vessel diameter changes also. But the most dramatic is the course of change of the zero-stress state. Typically, the time to reach 50 percent of asymptotic hypertrophy of blood vessel wall thickness is about 3-5 days. The corresponding time for blood pressure is about 7 days. The opening angle of the zero-stress state, however, increases rapidly at first, reaches a peak in about 2 to 4 days, then decreases gradually to a reduced asymptote. The exact values of the time constants depend on the location along the aortic tree. In general, the course of change of residual strain is very different from those of the blood pressure and the blood vessel wall thickness.

Animals↗

PubMed1989

Change of residual strains in arteries due to hypertrophy caused by aortic constriction.

The stress and strain that remain in an organ when the external load is removed are called residual stress and strain. They can be revealed by cutting up the organ in such a way as to reveal the zero-stress configuration. The function of the organ depends on the residual strain. For a blood vessel, the zero-stress configuration is very different from that of the no-load condition, and it changes over time when the physical stress acting on the vessel is changed. Data on rat aorta are presented. Physical changes were obtained by constricting the aorta at the celiac trunk level with a band of metal. Banding causes an increase of blood pressure and hypertrophy of the vessel in the upper body and a transient decrease of blood pressure in the lower body. If the aorta is cut transversely into rings and each ring is cut radially, it will open up into a noncircular arc, which may be characterized by its opening angle. It is shown that the opening angle varies systematically along the aorta and that it changes significantly together with changes of blood pressure and hypertrophy. In the ascending aorta, the opening angle increased from 171 degrees and to 214 degrees in 4 days after banding, then decreased gradually to an asymptotic value of 126 degrees in 40 days. At other sections, the swing of opening angle is smaller. The implications are discussed.

Animals↗

PubMed1989

Synthesis and non-thrombogenicity of polyurethanes with poly(oxyethylene) side chains in soft segment regions.

Epoxidized polybutadiene-urethanes were synthesized and grafted with poly(oxyethylene)s. The non-thrombogenicity of the graft polyurethanes was investigated in relation to the content of poly(oxyethylene). The grafting of poly(oxyethylene) to polyurethane suppressed adsorption and denaturation of plasma proteins and platelet adhesion. It was also found that there exists an optimum content of poly(oxyethylene) for the graft polyurethane to attain the highest non-thrombogenicity.

Adsorption↗

PubMed1989

[Characteristics of mucins and CEA in globoid dysplastic cells of human stomach and its relationship with signet ring cell carcinoma].

Fourty-three cases of globoid dysplasia and signet ring cell carcinoma were stained by mucin and CEA (ABC method). It was found that there were three kinds of mucins (neutral, sialo and sulphomucin in both globoid dysplastic cells and signet ring cells. The percentages of the three kinds of mucins seen in the two kinds of cells were not much different. It was indicated that the altered mucins in the gastric epithelial cells must be a sign of didifferentiation of the cells and the results of malfunction. The globoid dysplasia type I mainly contained neutral mucin whereas type II, the acid mucin was predominant, especially the sulphomucin. The CEA positive reaction became stronger as the atypia being remarkable, and the characteristics of distribution of CEA positive particles were similar in the two kinds of cells, namely, randomly or disorderly in the cells. Based on the analysis of the results, a conclusion can be made that the variety of mucins in globoid dysplastic cells can be used as a reference point in classification and is not much significant in grading, but the amount of CEA positive matter can be a reference point in grading. The globoid dysplasia is such a lesion with special features in morphology and function manifested in the process of didiferentiation towards signet ring cell carcinoma following the successive action of carcinogens upon the cells of gastric epithelium.

Adenocarcinoma, Mucinous↗

PubMed1989

Spectral properties of human placental aldose reductase and aldehyde reductase II.

Circular dichroism and fluorescence spectra of aldose reductase (E.C.1.1.1.21) and aldehyde reductase II (E.C.1.1.1.19) purified to homogeneity from human placenta have been studied. The alpha helical content of aldose reductase and aldehyde reductase II was 51% and 56%, respectively, whereas no beta helical structure was found in either case. In the case of aldose reductase, the secondary structure was unaffected at alkaline pH (9.5), whereas a drastic alteration in the structure was observed at 58 degrees C. The secondary structure of aldehyde reductase II, on the other hand, remained unaffected at higher pH and temperature.

Aldehyde Reductase↗

PubMed1989

[2 cases of familial multiple endocrine neoplasia syndrome].

Two cases of familial multiple endocrine neoplasia syndrome (MEN) are reported. Case 1. A 31-year-old woman began to have repeated attacks of coma in 1970. Blood examination showed fasting sugar as low as 2.05 mmol/L (37 mg/dl). Her disease was cured after the removal of two insulinomas in 1972. However, coma occurred again in 1982. Examination revealed the ratio of concentrations of serum insulin and sugar being more than 0.3. Another operation with removal of 19 insulinomas were performed in our hospital in 1985. After operation, the level of blood sugar returned to normal. Her father had suffered from Zollinger-Ellison Syndrome; the entire stomach and a part of pancreas were removed in 1967. So we examined her brother. His serum calcium level was 2.5-2.9 mmol/L (10.0-11.6 mg/dl) and plasma iPTH level 49.5-115.5 ng/L (normal value 21.4 +/- 7.7 ng/L n = 71). The high level of iPTH could not be suppressed by calcium load test. The total of two and a half of the remaining two parathyroid glands were removed. Pathology confirmed hyperplasia of parathyroid glands. The levels of serum calcium and iPTH returned to normal after operation. Case 2. A 25-year-old woman suffered from hypertension at the age of ten. Adrenal tumor with pheochromocytoma (2 x 2 x 1.5 cm3) was diagnosed and removed at that time. She complained of intermittent coma for 10 months and was thus admitted to our hospital in Nov. 1984. The level of blood sugar was 1.5-3.8 mmol/L (26-67 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma, Islet Cell↗

PubMed1989

[Metabolism of calcium and phosphorus in Cushing syndrome with osteoporosis].

52 patients with Cushing syndrome were studied. According to the appearance of X-ray film of bones, they were divided into three groups: (I) Without osteoporosis, 12 cases (23.1%), (II) Mild osteoporosis, 17 cases (32.7%), (III) Severe osteoporosis with fractured ribs and/or wedge-shaped vertebrae, 23 cases (44.2%). It was found that the mean level of serum calcium in the patients was significantly lower than that in 94 normal subjects (mean +/- S 2.3 +/- 0.2 versus 2.4 +/- 0.1 mmol/L P less than 0.001). The mean concentrations of blood alkaline phosphatase and parathyroid hormone in the patients were much higher than those in normal subjects (65.0 +/- 27.6 versus 42.6 +/- 15.6 IU/L P less than 0.001, 44.6 +/- 22.4 versus 20.6 +/- 8.0 pg/ml P less than 0.001 respectively). The mean level of serum 25 (OH)-D in the patients was significantly lower than that in controls (10.9 +/- 5.6 versus 16.2 +/- 4.6 ng/ml P less than 0.001). Urinary calcium excretion increased in the patients as compared with that in controls (P less than 0.01). The urinary calcium excretion correlated well with the blood total cortisol and urinary free cortisol. It is suggested that hypercalciuria might cause decrease of serum calcium. Thus the parathyroid glands were stimulated and the parathyroid hormone (PTH) secretion was increased. Excess of PTH stimulates bone resorption. All of these factors are involved in the pathogenesis of osteopenia in Cushing's syndrome.

Adolescent↗

PubMed1989

[Study on the introduction of the cultivation of Aucklandia lappa Deone].

Tests were conducted on some aspects of breeding Aucklandia lappa in the course of introduction: climatic conditions, cultivating techniques, field management, growth cycle, harvest and processing, thus providing a scientific basis for the introduce, cultivation and higher production of Aucklandia lappa.

Altitude↗

PubMed1989

[Clinical significance of competitive protein binding assay of 25-hydroxyvitamin D concentration].

The level of serum 25-hydroxyvitamin D (25-OH-D3) was determined in 94 cases of healthy volunteers and 98 patients with various diseases. The mean level of the controls was 16.2 +/- 4.6 ng/ml (x /- S). The patients were divided into 5 groups, 1) Osteomalacia and rickets 42 cases, showing typical changes of bone in X-ray films. In 12 of them the disease was caused by vitamin D deficiency. The mean value of 25-OH-D3 was 3.3 +/- 2.0 ng/ml, being much lower than that of controls (P less than 0.001). In 14 cases of hypophosphatemia, 8 cases of renal tubular acidosis and 8 cases of renal insufficiency all complicated with osteomalacia the mean value of 25-OH-D3 was 17.9 +/- 11.4, 18.2 +/- 9.6 and 19.2 +/- 5.6 ng/ml (P greater than 0.05) respectively. 2) Intestinal malabsorption 18 cases. The mean level of 25-OH-D3 was 4.5 +/- 3.2 ng/ml (P less than 0.001). Some of them had hypocalcemia and/or secondary hyperparathyroidism. 2 showed osteoporosis and 1 osteomalacia. 3) Chronic liver disease 24 cases, the mean value of 25-OH-D3 was 6.2 +/- 5.6 ng/ml, being much lower than that of the controls (P less than 0.001). 4) 10 cases after taking anti-epileptic drugs had a mean level of 25-OH-C3 6.9 +/- 5.8 ng/ml (P less than 0.001). 1 had X-ray evidence of osteomalacia. 5) 4 cases of overdosage of vitamin D had a mean value of 110.3 +/- 22.5 ng/ml, being much higher than that of the controls (P less than 0.001). Competitive protein binding assay for measuring 25-OH-D3 is a simple and economic method. It is sensitive and specific as it provides distinct discrimination between healthy controls and patients with vitamin D deficiency or overdosage.

Adult↗

PubMed1988

Trauma of lung due to impact load.

A quantitative evaluation of lung injury due to impact loading is of general interest. Hemorrhage and edema are the usual sequelae to traumatic pulmonary impact. To gain some quantitative understanding of the phenomena, we perfused excised rabbit lung with Macrodex at isogravimetric condition and monitored lung weight continuously after impact. It is shown that a factor of importance is the rigidity of the surface on which the lung rests. The rate of lung weight increase is smaller if the lung was 'freely' supported on a soft cloth, more if it was supported on a rigid plate. This suggests the influence of stress wave reflection. The critical condition correlates with the initial velocity of impact at the surface of the lung, or with the maximum deflection. For a freely supported lung, the rate of lung weight increase was 22% of the initial total lung weight per h after impact when the impact velocity was 11.5 ms-1, 30% when the velocity was 13.2 ms-1, several 100% at 13.5 ms-1, signaling massive lung injury. Since the velocity of sound in rabbit lung is 33.3 ms-1 when the inflation (transpulmonary) pressure is 10 cm H2O, the critical velocity of 13.5 ms-1 corresponds to a Mach number of 0.4. The maximum surface displacement of the lung is almost linearly proportional to the initial velocity of impact. The exact cause of edema and hemorrhage is unknown; we hypothesize that it is due to tensile stress in the alveolar wall caused by the impact.

Animals↗

PubMed1988

A hypothesis on the mechanism of trauma of lung tissue subjected to impact load.

When a compressive impact load is applied on the chest, as in automobile crash or bomb explosion, the lung may be injured and show evidences of edema and hemorrhage. Since soft tissues have good strength in compression, why does a compression wave cause edema? Our hypothesis is that tensile and shear stresses are induced in the alveolar wall on rebound from compression, and that the maximum principal stress (tensile) may exceed critical values for increased permeability of the epithelium to small solutes, or even fracture. Furthermore, small airways may collapse and trap gas in alveoli at a critical strain, causing traumatic atelectasis. The collapsed airways reopen at a higher strain after the wave passes, during which the expansion of the trapped gas will induce additional tension in the alveolar wall. To test this hypothesis, we made three new experiments: (1), measuring the effect of transient overstretch of the alveolar membrane on the rate of lung weight increase; (2) determining the critical pressure for reopening collapsed airways of rabbit lung subjected to cyclic compression and expansion; (3) cyclic compression of lung with trachea closed. We found that in isolated rabbit lung overstretching increases the rate of edema fluid formation, that the critical strain for airway reopening is higher than that for closing, and that these critical strains are strain-rate dependent, but independent of the state of the trachea, whether it is open or closed. Furthermore, a theoretical analysis is presented to show that the maximum principal (tensile) stress is of the same order of magnitude as the maximum initial compressive stress at certain localities of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Zero-stress states of arteries.

The no-load configuration of a living organ is, in general, not the zero-stress state. The difference can be revealed by cutting up an unloaded organ to such an extent that the stress becomes zero in the tissue everywhere. For the aorta, it is shown that the configuration of the zero-stress state differs considerably from being a cylindrical tube. It is, in fact, an open sector with opening angles varying along the arterial tree. This article presents data on the zero-stress state in the arteries of the rat in normal condition.

Animals↗

PubMed1988