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Biomedical subjects

X Shi

Publications and source records attributed to X Shi.

At least 253 records · Page 14Linked to original sources
PubMed1998

Thermal stresses from large volumetric expansion during freezing of biomaterials.

Thermal stresses were studied in freezing of biomaterials containing significant amounts of water. An apparent specific heat formulation of the energy equation and a viscoelastic model for the mechanics problem were used to analyze the transient axi-symmetric freezing of a long cylinder. Viscoelastic properties were measured in an Instron machine. Results show that, before phase change occurs at any location, both radial and circumferential stresses are tensile and keep increasing until phase change begins. The maximum principal tensile stress during phase change increases with a decrease in boundary temperature (faster cooling). This is consistent with experimentally observed fractures at a lower boundary temperature. Large volumetric expansion during water to ice transformation was shown to be the primary contributor to large stress development. For very rapid freezing, relaxation may not be significant, and an elastic model may be sufficient.

Anisotropy↗
PubMed1998

Effect of hypohydration on gastric emptying and intestinal absorption during exercise.

Dehydration and hyperthermia may impair gastric emptying (GE) during exercise; the effect of these alterations on intestinal water flux (WF) is unknown. Thus the purpose of this study was to determine the effect of hypohydration ( approximately 2.7% body weight) on GE and WF of a water placebo (WP) during cycling exercise (85 min, 65% maximal oxygen uptake) in a cool environment (22 degrees C) and to also compare GE and WF of three carbohydrate-electrolyte solutions (CES) while the subjects were hypohydrated. GE and WF were determined simultaneously by a nasogastric tube placed in the gastric antrum and via a multilumen tube that spanned the duodenum and the first 25 cm of jejunum. Hypohydration was attained 12-16 h before experiments by low-intensity exercise in a hot (45 degrees C), humid (relative humidity 50%) environment. Seven healthy subjects (age 26.7 +/- 1.7 yr, maximal oxygen uptake 55.9 +/- 8.2 ml . kg-1 . min-1) ingested either WP or a 6% (330 mosmol), 8% (400 mosmol), or a 9% (590 mosmol) CES the morning following hypohydration. For comparison, subjects ingested WP after a euhydration protocol. Solutions ( approximately 2.0 liters total) were ingested as a large bolus (4.6 ml/kg body wt) 5 min before exercise and as small serial feedings (2.3 ml/kg body wt) every 10 min of exercise. Average GE rates were not different among conditions (P > 0.05). Mean (+/-SE) values for WF were also similar (P > 0.05) for the euhydration (15.3 +/- 1.7 ml . cm-1 . h-1) and hypohydration (18.3 +/- 2.6 ml . cm-1 . h-1) experiments. During exercise after hypohydration, water absorption was greater (P < 0.05) with ingestion of WP (18.3 +/- 2. 6) and the 6% CES (16.5 +/- 3.7), compared with the 8% CES (6.9 +/- 1.5) and the 9% CES (1.8 +/- 1.7). Mean values for final core temperature (38.6 +/- 0.1 degrees C), heart rate (152 +/- 1 beats/min), and change in plasma volume (-5.7 +/- 0.7%) were similar among experimental trials. We conclude that 1) hypohydration to approximately 3% body weight does not impair GE or fluid absorption during moderate exercise when ingesting WP, and 2) hyperosmolality (>400 mosmol) reduced WF in the proximal intestine.

Adult↗
PubMed1998

Reactive oxygen species: their relation to pneumoconiosis and carcinogenesis.

Occupational exposures to mineral particles cause pneumoconiosis and other diseases, including cancer. Recent studies have suggested that reactive oxygen species (ROS) may play a key role in the mechanisms of disease initiation and progression following exposure to these particles. ROS-induced primary stimuli result in the increased secretion of proinflammatory cytokines and other mediators, promoting events that appear to be important in the progression of cell injury and pulmonary disease. We have provided evidence supporting the hypothesis that inhalation of insoluble particles such as asbestos, agricultural dusts, coal, crystalline silica, and inorganic dust can be involved in facilitating multiple pathways for persistent generation of ROS, which may lead to a continuum of inflammation leading to progression of disease. This article briefly summarizes some of the recent findings from our laboratories with emphasis on the molecular events by which ROS are involved in promoting pneumoconiosis and carcinogenesis.

Animals↗
PubMed1998

Fluid and carbohydrate replacement during intermittent exercise.

Most studies relating to fluid replacement have addressed the problem of drinking during prolonged exercise. Fluid replacement is also very important for intermittent exercise, although it has not been extensively studied. More studies in this area would help coaches and athletes understand the importance of fluid balance and carbohydrate supplementation during intermittent exercise. Based on available data, it can be concluded that: (i) because of high exercise intensity, sweat loss and glycogen depletion during intermittent exercise are at least comparable with those during continuous exercise for a similar period of time. Therefore, the need to ingest a sport drink or replacement beverage during intermittent exercise may be greater than that during continuous exercise in order to maintain a high level of performance and to help prevent the possibility of thermal injury when such activity occurs in a warm environment; (ii) the volume of ingested fluid is critical for both rapid gastric emptying and complete rehydration; and (iii) osmolality (250 to 370 mOsm/kg), carbohydrate concentration (5 to 7%), and carbohydrate type (multiple transportable carbohydrates) should be considered when choosing an effective beverage for rehydration and carbohydrate supplementation during intermittent exercise.

Adult↗
PubMed1998

Laboratory evaluations of three dentifrices with polishing or brushing.

The purpose of this study was to determine the depth of deposit removal of three dentifrices using a dental felt polishing tip or an Oral-B P 35 toothbrush. The dentifrices were compared using a laboratory method which simulates clinical tooth polishing or toothbrushing procedures, and utilizes a pressure-sensitive paper that records the depth of deposit removal. Each polishing time was conducted for five seconds; toothbrushing time was 15 seconds. Both polishing and toothbrushing were performed at a weight of 250 grams. Depth of Deposit Removal (DDR) was recorded using a 0-4 scale from a comparative color chart. The dentifrices evaluated were Arm & Hammer Dental Care, Colgate Regular, and Crest Regular. Twenty-four replicates of each dentifrice, tested undiluted, were performed. Results indicated that dentifrice efficacy was ranked numerically as Arm & Hammer Dental Care > Colgate Regular > Crest Regular. In all of the assays the Arm & Hammer Dental Care dentifrice had significantly (p < 0.01-0.001) higher DDR mean values compared to the Colgate Regular and Crest Regular dentifrices. The Colgate Regular dentifrice was significantly (p < 0.01-0.001) superior to the Crest Regular dentifrice in the assays conducted.

Dental Deposits↗
PubMed1998

[Detection of 17-ketosteroid and 17-hydroxycorticosteroid in urine after separation and collection by foam rubber].

Using foam rubber 17-ketosteroid (17-KS) and 17-hydroxycorticosteroid (17-OHCS) were separated and collected in urine. 17-KS and 17-OHCS were eluted down from the foam rubber with alcohol, colour reaction can be respectively produced by m-dinitrobenzene and phenyhydrazine hydrocholoride, then both of them were detected by spectro-photometry. The standard deviation of this method was +/- 0.032, and its minimum detectable concentration was 0.01 microgram.ml-1. The recovery rate of 17-KS and 17-OHCS estimation was from 99.0% to 101.0%, with co-efficients of variation less than 6.23%.

17-Hydroxycorticosteroids↗
PubMed1998

[Prospective study on the correlation factors of fetal macrosomia].

The increase of body weight in pregnancy women, 50 g oral glucose challenge test (50 g GCT), pregnant women and umbilicus vein blood insulin (INS), growth hormone (GH), glucose and neonate weight were measured in 110 pregnant women and their neonates were measured to explore the correlation factors of fetal macrosomia. The incidence of macrosomia was higher in pregnant women whose increased weight > or = 15 kg than those < 15 kg. 50 g GCT plasma glucose showed positive correlation with neonatal weight. Which was higher in the group of the fetal macrosomia than of the normal neonates. The results suggest that both the increasing weight of the pregnant women and the 50 g GCT are related parameters to predict fetal macrosomia. To prevent fetal macrosomia the diet should be limited in those who have had a high increasing body weight in pregnancy and appropriate intervention is required to those whose 50 g GCT are positive.

Adult↗
PubMed1998

[Laboratory diagnosis of Chlamydia trachomatis and Ureaplasma urealyticum of chronic prostatitis].

Prostatic fluid taken from 1038 cases of chronic prostatitis were detected by fluorescent monoclonal antibody technique and isolating cultural method for Chlamydia Trachomatis (CT) and Ureaplasma Urealyticum (UU). The control group consisted of 80 cases. CT and UU were not found in control group. The positive rates of CT and UU infection were 28.4% and 33.0% respectively in the tested group whose cases were abacterial prostatitis. The results suggested that CT and UU are pathogens causing chronic abacterial prostatitis.

Adult↗
PubMed1998

[Clinical evaluation of several tumor markers in the diagnosis of primary hepatic cancer].

OBJECTIVE: To evaluate the practical significance of alphafetoprotein(AFP), alpha-L-fucosidase(AFu), gamma-glutamyltransferase(GGT), sialic acid(SA) and carcinoembryonic antigen(CEA) in the diagnosis of primary hepatic cancer(PHC). METHODS: AFP, AFu, GGT, SA and CEA in the serum were studied in 67 patients with PHC, 8 with hepatic metastasis of gastrointestinal cancer, 89 with benign liver diseases and in 131 controls without liver diseases. RESULTS: According to statistics, the sensitivity of AFP, AFu, GGT, SA and CEA in the diagnosis of PHC was 65.4%, 70.8%, 34.8%, 60.2% and 36.4% repectively; their specificity was 92.6%, 98.1%, 87.1%, 94.5% and 77.8% respectively. CEA in hepatic metastasis of gastrointestinal cancer was higher than that in the other groups of patients. Simultaneous detection of AFP, AFu GGT and CEA gave a diagnostic sensitivity and specificity in PHC of 81.4% and 91.6% respectively. CONCLUSION: AFP and AFu are superior to GGT, SA and CEA in the diagnosis of PHC; simultaneous detection of AFP, AFu, GGT and SA might increase the diagnositic sensitivity and specificity of PHC. CEA was less helpful in the diagnosis of PHC, but might be used to differentiate PHC from hepatic metastasis of gastrointestinal cancer.

Adolescent↗
PubMed1998

[In vitro study on arsenic trioxide-induced apoptosis of retinoic acid resistant acute promyelocytic leukemia cell line(MR-2)].

OBJECTIVE: To study the possible mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: Retinoic acid resistant APL cell line MR-2 was used as in vitro model. The effect of As2O3 on MR-2 cell line was observed by cell viability, cell growth, cell morphology, flow cytometry assay, NBT reduction test and immunofluorescence analysis. RESULTS: 1.0 mumol/L of As2O3 could induce apoptosis of MR-2 cells and it correlated with the degradation of PML-RAR alpha fusion protein. CONCLUSIONS: The therapeutic effect of As2O3 for APL possibly differs from that of ATRA, however, PML-RAR alpha fusion protein may be the target of both the therapy.

Antineoplastic Agents↗
PubMed1998

[The effect of endothelium-derived relaxation factor on specific property of vasomotion of cochlea in guinea pig].

By using intravital microscopy measurement with image processing system, continuous diameter changes were measured by self-tracking with computer, the present study is to investigate specific property of vasomotion in cochlear microvessels and its responsibility to the endothelium-derived relaxation factor (EDRF/NO). The results demonstrated that the vasomotion of cochlear arteriole existed in normal condition in a small pattern. It was found that the vasomotion was significantly enhanced after administration of L-arginine(which is donor of EDRF/NO), and L-arginine induces a sequence of changes in cochlear blood flow. There were significant statistic difference before and after the drug administration. The conclusion suggest that EDRF/NO play an important role in the increase of blood flow by improvement of vasomotion.

Animals↗
PubMed1998

[Effect of electroacupuncture on succinate dehydrogenase of gentamycin induced ototoxic cochlear hair cells in guinea pigs].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on succinate dehydrogenase (SDH) of gentamycin (GE) induced ototoxic cochlear hair cells. METHODS: Preyer's reflex normal guinea pigs were selected and divided randomly into three groups: GE group, EA group, control group. Brainstem auditory evoked potential (BAEP) and SDH in the cochlear hair cells were taken as indexes. In the animals of GE group GE was alone injected intramuscularly 80 mg.kg-1.d-1 for 20 days, while in the animals of EA group GE and additional EA was applied once a day on Tinggong (SI19), Yifeng(SJ17) and Shenshu (UB23) points. EA lasted for 15 minutes. RESULTS: In the GE group BAEP reaction threshold rose markedly, while that rose slightly in EA group. The difference was significant between two groups (P < 0.05). The change of SDH within cochlear hair cells and degree of hair cells injury in the EA group were lower than those in GE group. CONCLUSIONS: EA therapy could relieve GE ototoxicity, protect SDH in cochlear hair cells and might be a possible mechanism of action of EA.

Animals↗
PubMed1998

[Changes of T-SOD activity and MDA, GSH contents in blood of guinea pigs after exposure to narrow-band noise].

In order to evaluate the changes of lipid peroxide response induced by free radical after intense noise exposure, levels of T-SOD and MDA in serum and GSH in blood of guinea pigs were determined. Sixty male adult guinea pigs were used. The narrow band noise was centered at 1000Hz with 100Hz band width 126 dB SPL. It was found: 1) SOD activity in serum increased after 5d exposure (P > 0.05), but decreased after 10d exposure (P > 0. 05); 2) contents of MDA in serum increased (P < 0.05) and contents of GSH in blood decreased with increase of exposure time (P < 0.01). It shows that the lipid peroxide response induced by free radicals increased after intense noise exposure and it is possible to use free radical scavengers and/or antioxidant in prevention and treatment of noise induced damage.

Animals↗
PubMed1998

[A specific property of microvasomotion in the guinea pig cochlea].

OBJECTIVE: To investigate specific property of vasomotion in cochlear microvessels and its response to the endothelium-derived relaxation factor (EDRF). METHODS: The dynamic changes of cochlea microvessels were observed using intravital microscopy and measured by the microcirculatory image processing system. The frequency and amplitude of vasomotion were analyzed with fast Fourier transform (FFT) according to the diameter changes. RESULTS: The vasomotion of cochlear arteriole with a small amplitude existed in normal condition. The diameter changed from (10.41 +/- 3.03) microns to (12.29 +/- 1.9) microns with a mean value of (11.2 +/- 2.7) microns. The specific property of vasomotion was characterized by a frequency (0.021 +/- 0.002) Hz and amplitude of (0.37 +/- 0.11) micron. The contraction index was determined as 0.42 +/- 0.17. The vasomotion was significantly enhanced after the administration of EDRF. CONCLUSION: The vasomotion existed in the cochlea and EDRF can increase the cochlear blood flow by improving the vasomotion.

Animals↗
PubMed1998

[Primitive neuroectodermal tumor of bone and soft tissue].

OBJECTIVE: To study the pathological characteristics of primitive neuroectodermal tumor (PNET) of bone and soft tissue. METHOD: Five patients with bone and soft tissue of PNET (2 men and 3 women) were studied by light microscope and immunohistochemistry. The age of the patients was 18, 18, 43, 14, 32 years and the primary sites of involvement were the ilium (n = 2), axillary fossa (n = 1), condyle of femur (n = 1), and diploe (n = 1). X-ray films showed bone osteolytic destruction, and no periosteal reaction or calcification. Surgery was performed in the patients. RESULT: All patients received combined chemotherapy and 3 received radiotherapy. Three patients died of metastatic tumor of lung 20, 13, and 5 months after invasion. 1 patient metastatic tumor of lung 20 months after invasion, and 1 patient bone extensive metastasis 1.5 months after surgery. CONCLUSION: The treatment of PNET of bone and soft tissue awaits further study.

Adolescent↗
PubMed1998

[Living related liver transplantation: a case report].

OBJECTIVE: To study a case of living related liver transplantation. METHOD: The patient was a 10-year-old girl who suffered from congenital diffuse intrahepatic cholangiectasis, recurrent cholangitis and hepatocirrhosis. The donor was the patient's father aged 40. The left lateral lobe of donor's liver was cut and grafted to the patient. Intensive care and treatment as well as follow-up were given after operation. RESULT: For the donor, the operation lasted 400 min, with 410 ml bleeding and 300 g liver removed. The recovery was satisfactory. For the recipient, the operation lasted 652 min, with 1665 ml bleeding, 80 min non-liver stage, 0 min graft hot ischemic stage, and 137 min cold ischemic stage. Immunosuppressive therapy was given using cyclosporin A, azathioprine and adrenocortical hormones. There was an acute rejection 11 days after operation, which was controlled using hormone impulsive therapy. The patient has been surviving 7 months with normal liver function. CONCLUSION: The living related liver transplantation is feasible under modern surgical conditions. It is demonstrated that perfect postoperative management is the key for the successful liver transplantation.

Adult↗
PubMed1998

[Determination of polyamines in pyronaridine-sensitive and -resistant Plasmodium berghei-infected erythrocytes].

AIM: To understand the relationship between polyamine metabolism and pyronaridine resistance of malaria parasites. METHODS: Kunming strain mice weighing 18 g-22 g were inoculated intraperitoneally with Plasmodium berghei ANKA strain (pyronaridine-sensitive, PS), and P. berghei ANKA strain low and high pyronaridine resistant lines (PRA and PRB), respectively. Seven days after inoculation, blood samples were collected and WBC in the blood were removed by the method of chromatography using SE-cellulose and Sephadex G25 (1:2). After thin layer chromatography, the contents of three polyamines, i.e. putrescine(PTC), spermidine (SPD), and spermine(SPM) in normal and infected erythrocytes were determined with fluorescence spectrometer. The changes of polyamine level in PS and PRB infected erythrocytes of mice treated by a single oral dose of PND 5 and 10 mg/kg respectively were also observed. RESULTS: The contents of PTC, SPD and SPM in PS infected erythrocytes were 47.5 +/- 28.6, 97.7 +/- 34.0 and 81.7 +/- 23.8 nmol/10(9) RBC (n = 9), respectively, being 1.5, 3.5, and 6.6 times of those appeared in the normal RBC (32.0 +/- 9.9, 28.2 +/- 12.3, and 12.4 +/- 15.0 nmol/10(9) RBC, n = 9), respectively. The differences between two groups were significant. Interestingly, when mice infected with pyronaridine resistant line PRA and PRB, the contents of PTC, SPD and SPM in the infected erythrocytes increased to 187.7 +/- 139.9, 258.3 +/- 137.9 and 142.8 +/- 143.8 nmol/10(9) RBC (n = 18), and 345.5 +/- 223.0, 435.8 +/- 265.4 and 189.4 +/- 171.7 noml/10(9) RBC, respectively. Except for SPM, PTC and SPD in the PRA and PRB infected erythrocytes were significantly higher than those in the PS and PRA infected erythrocytes, respectively, being 3.9, 2.6 and 1.8, 1.7 times of those appeared in PS and PRA infected erythrocytes. In PND treated group, SPD and SPM contents of PS infected erythrocytes were decreased by 31.6% and 47.3% compared with non-treated group, but the polyamine level of PRB infected erythrocytes did not significantly change after PND administration. CONCLUSION: The resistance of P. berghei to PND is related to the alteration of polyamine metabolism in the malarial parasites.

Animals↗