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Biomedical subjects

Q Y Guo

Publications and source records attributed to Q Y Guo.

11 recordsLinked to original sources
PubMed2006

Usefulness of diffusion/perfusion-weighted MRI in patients with non-enhancing supratentorial brain gliomas: a valuable tool to predict tumour grading?

22 patients with non-enhancing supratentorial gliomas on contrast-enhanced MRI underwent both diffusion- and perfusion-weighted MRI (DWI/PWI) before surgical resection. 14 low-grade gliomas (WHO Grade I and II) and 8 anaplastic gliomas were verified histologically. Both apparent diffusion coefficient (ADC) values and relative cerebral blood volume (rCBV) ratios were calculated on the solid portion of the tumour, on peritumoural area, as well as on the contralateral normal white matter, respectively. The results showed that lower ADC values were present in the solid portions of anaplastic gliomas, but not in low grade (p < 0.01). All ADC values in peritumoural regions of tumours were decreased compared with the contralateral normal white matter. However, there was no significant difference between anaplastic gliomas and low-grade gliomas. Meanwhile, higher rCBV ratios were present in both solid portions and peritumoural regions of anaplastic gliomas, but not in low grade gliomas (p < 0.01). In conclusion, non-enhancing brain gliomas with lower ADC values in the solid portions and higher rCBV ratios in both solid portions and peritumoural regions of tumours are significantly correlated with anaplasia. Therefore, DWI and PWI should be integrated in the diagnostic work-up of non-enhancing gliomas in order to predict grading.

Adult↗
PubMed2006

Potential of diffusion tensor MRI in the assessment of periventricular leukomalacia.

AIM: To investigate magnetic resonance (MR) diffusion tensor imaging (DTI) and fibre tractography in the assessment of altered major white matter (WM) fibre tracts in periventricular leukomalacia (PVL). MATERIALS AND METHODS: Twelve children (male:female = 7:5, age range 3-10 years; mean age = 6.5 years) who had suffered PVL were included in this study. Meanwhile, Twelve age-matched normal controls (male:female = 6:6, age range 4-12 years; mean age = 7.3 years) with normal MRI findings and no neurological abnormalities were recruited for comparison. DTI was performed with 15 different diffusion gradient directions and DTI colour maps were created from fractional anisotropy (FA) values and the three vector elements. To identify alteration of WM fibre tracts in patient of PVL quantitatively, FA values on diffusion tensor colour maps were compared between the patients and controls. Quantitative analysis was performed using the regions of interest (ROI) method settled on the central part of all identifiable WM fibres, including the corticospinal tract (CST) in the brainstem, middle cerebellar peduncle (MCP), medial lemniscus (ML), anterior/posterior limb of internal capsule (ICAL/ICPL), arcuate fasciculus (AF), posterior thalamic radiation (PTR), genu of corpus callosum (GCC), splenium of corpus callosum (SCC), corona radiata (CR), cingulum (CG), and superior longitudinal fasciculus (SLF). The averaged FA value of each WM fibre was measured and summarized as the mean +/- standard deviation (SD). All data were analysed by paired Student's t-test. A p-value of less than 0.05 was considered to indicate statistical significance. RESULTS: Visual investigation of WM fibre tracts showed that the ICAL, brainstem CST, ML, MCP, and external capsule (EC) was similar in controls and subjects. However, the ICPL, AF, PTR, CR, CG, SLF and corpus callosum, were all attenuated in size. All 12 cases of PVL showed a significant mean FA reduction in the ICPL, AF, PTR, CR, CG, SLF, SCC, and GCC in comparison with the ipsilateral regions of healthy controls (p<0.05). However, there were no statistically significant differences of the ICAL, ML, MCP, and brainstem CST when analysed using a two-tailed Student's t-test for paired data (p>0.01). CONCLUSION: DTI can provide more information for understanding the pathophysiology of motor disability and associated sensory handicap in PVL.

Anisotropy↗
PubMed2005

Investigation of the release of aspirin from spray-congealed micro-pellets.

The release behaviour of aspirin from spray-congealed hydrogenated soybean oil micro-pellets of different sizes was studied. The purpose of this study was to investigate the effect of particle size of micro-pellets on the drug release profile and mechanism. Micro-pellets produced were sieved into several fractions and their drug content and dissolution profiles in two media were determined. The dissolution mechanism was studied by fitting the data to release kinetic models. Micro-pellets with high encapsulation efficiency were successfully produced. The micro-pellets were able to sustain the release of aspirin in pH 1.2 and pH 6.8 dissolution media. As particle size of micro-pellets increased, the drug release rate decreased. The drug release mechanism was affected by the size of micro-pellets. Micro-pellets in the range of 90-250 microm tended to follow the first order or Higuchi model. However, micro-pellets in the range of 250-355 microm were found to follow zero-order release model. This result showed that drug release could be modified by controlling the size of micro-pellets and that controlled release of drug might be achieved by using larger size micro-pellets.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Phospholipids in dialysate and the peritoneal surface layer.

Dialysate concentration of phospholipids has been used to monitor peritoneal membrane status. However, we recently found that the peritoneum has a surface layer in which phospholipids may be the main constituent. Therefore, in this study, we compared the phospholipids composition of peritoneal dialysate and of the peritoneal surface in rats. Eight male Sprague-Dawley rats were used in the study. Five rats received an intraperitoneal injection of 25 mL 4.25% glucose dialysis solution. After four hours, the rats were killed, and the dialysate was drained completely. Then 20 mL of Folch solution was infused into the peritoneal cavity for 30 seconds and drained completely. The other three rats received the Folch solution without dialysis. The effluent and Folch solution were then processed for phospholipids analysis using high performance thin-layer chromatography (HPTLC). The total phospholipids content was ten times higher in the surface layer than in the dialysate effluent. In the effluent, four clearly different components were seen: lysophosphatidylcholine (LPC), sphingomyelin (SM, 29%), phosphatidylcholine (PC, 66%), and phosphatidylinositol (PI, 4.5%). However, in the surface layer, as well as LPC, SM (20.6%), PHC (47%), and PI (6.3%), two additional components were seen, phosphatidylserine (PS, 17.1%) and phosphatidylethanolamine (PE, 8.9%). The quantity of phospholipids in the peritoneal surface of non dialyzed rats was similar to the total quantity of phospholipids (in effluent and in the peritoneal surface) of dialyzed rats. Our results suggest that: (1) a surface layer is present on the peritoneum; this layer could well be extracted by Folch solution; and, with appropriate incubation time, one can separate the surface layer without damaging the mesothelial cells; (2) the composition of phospholipids in the effluent is different from that in the peritoneal surface layer, which contains membrane phospholipids (PS and PE); (3) shielding from the peritoneal surface may be the main reason for the presence of phospholipids in the dialysate.

Animals↗
PubMed2000

Comparison of three chronic dialysis models.

The chronic peritoneal dialysis model is important for understanding the pathophysiology of peritoneal transport and for studying biocompatibility of peritoneal dialysis solutions. In this study, we compared three different chronic peritoneal dialysis models. A peritoneal catheter was placed in 23 male Sprague-Dawley rats, 12 of which had an intact omentum (model 1) and 11 of which received an omentectomy (model 2). Seven other rats, without a catheter, received a daily intraperitoneal injection (model 3). Each rat received a daily infusion of 25 mL of 3.86% glucose dialysis solution either through the catheter (models 1 and 2) or through injection (model 3) for 4 weeks. Then, a 4-hour dwell study using 3.86% glucose solution with an intraperitoneal volume marker and frequent dialysate and blood sampling was performed in each rat. The intraperitoneal volume was significantly lower in all the dialysis groups as compared to a control group (n = 6) in which the rats had no chronic dialysate exposure. The peritoneal fluid absorption rate, as well as the direct lymphatic absorption rate, was significantly higher in the three dialysis groups as compared to the control group. In general, no significant differences were seen in any of the parameters among the three dialysis models. Owing to catheter obstruction, three rats in model 1 and four rats in model 2 were lost during dialysis. Histological examination showed no significant differences among the three dialysis groups. Our results suggest that omentectomy may not be necessary in the chronic peritoneal dialysis model when using dialysate infusion and no drainage. Based on the present study, we think that perhaps model 1 may be the method of choice to test new peritoneal dialysis solutions. However, owing to its simplicity, model 3 could also be used if great care is taken to avoid puncturing the intestine or injecting into the abdominal wall.

Absorption↗
PubMed1996

Imaging approach to the diagnosis of pulmonary sequestration.

PURPOSE: To describe the characteristic features of pulmonary sequestration (PS), to evaluate the usefulness of various imaging modalities, and to find a rational approach to accurate diagnosis. MATERIAL AND METHODS: Twenty-four patients with PS proved by operation and pathology were reviewed retrospectively. Plain chest films were done in all patients, bronchography in 3, sonography in 14, CT in 6 (including CT angiography in 1 case), MR in 8 (including MR angiography in 1 case) and aortography in 12 (including DSA in 1 case). RESULTS: Plain chest films demonstrated a solid mass in 14 patients and a cystic mass in 10. Bronchograms showed displacement of adjacent bronchi with no filling of contrast medium within the lesion in 2 cases, while another case had a blind intermediate portion of the right bronchus (hypoplasia of middle and lower lobes associated with extralobar sequestration). Sonography demonstrated a solid lung mass in 12 cases and a solid mass with cystic areas in 2, and detected vessel-like structures within the mass or in its surroundings in 12. Doppler analysis showed arterial spectral wave confirming a feeding artery. CT revealed a solid mass in all patients, a mass with low density area in 4, and emphysema surrounding the mass in 3. MR imaging depicted anomalous arteries in all patients and venous drainage in 4 cases. Aortography demonstrated anomalous systemic arterial supply to the PS in all patients. In this series, 21 cases (87.5%) were correctly diagnosed preoperatively by the imaging modalities. CONCLUSION: Plain chest films can provide a diagnostic clue to PS. Sonography, CT and MR are helpful for showing arterial blood supply and for making a definite diagnosis. We recommend a rational imaging approach for the diagnosis of PS.

Adolescent↗
PubMed1994

[Studies on immobilization of suspension cells of peltate yam (Dioscorea zingiberensis C.H. Wright)].

The suspension cells of D. zingiberensis were immobilized with 3% sodium alginate, and then cultured in MS+2, 4-D1.0 + 6-BA 0.1 at 25 degrees C for a long period of time. The culture fluid free from cells was extracted and analyzed by TLC. The result showed that the immobilized cells could secrete the main component of D. zingiberensis--diosgenin, but not consecutively.

Cells, Cultured↗
PubMed1992

[The effect of antipsychotic drugs on dopamine-receptors on caudate calf].

Using radioligand receptor binding assay (RRA), dopamine receptor in the calf caudate were identified with 3H-Spiperone as radioactive ligand. The total number of maximal binding sites (Bmax), the equilibrium dissociation affinity (Kd), the concentrations of drug required to inhibited 50% specific binding (Ic50) and competitive inhibition constant (Ki) of antipsychotics in calf caudate were determined by sturative binding experiment and inhibitive binding experiment. The result showed the mean Bmax was 0.659 pmol/mg protein membrane and Kd was 0.31 nmol/L. Scatchard analysis denotes that it was hyperbole and there were two binding positions in calf caudte. Antipsychotics can inhibit 3H-Spiperone binding specifically the order of affinity constants (1/Ki) was Haloperdol and sulpiride, Chlorpromazine and Clozapin, Tranquis and Taractan. This abilities of drugs to compete with 3H-Spi binding will be used as basis of RRA for measuring blood levels of antipsychotics.

Animals↗
PubMed1991

[Pharmacokinetic study of adriamycin in the emulsion mixed with lipiodol-difference resulting from composition and methods of preparation, and behavior after mesenteric arterial injection in rat].

We experimentally investigated the pharmacokinetics of adriamycin (ADM) in a similar of transcatheter arterial chemoembolization therapy (TAE) of hepatocellular carcinoma using emulsion of lipiodol (Lp) mixed with ADM followed by gelatin sponge, and the difference resulting from composition and method of preparation of the emulsion as well as behavior after mesenteric arterial injection in rat. In in vitro study, the emulsion with iopamidol (iopamiron 300 : IP) was more stable than with amidotrizoic acid (60% Urografin : UG). The highest stability was found in the mixing ratio of Lp. IP and distilled water at 1 : 0.42 : 0.08. Frequent pumping also made the emulsion more stable. But in optimally composed emulsion, pumping 20 or 50 times made no difference in the stability during 30 min. which may be longer than the time from preparation to injection time of the emulsion in clinical application. After injection of the emulsion into the mesenteric artery which may simulate injection into the hepatic artery in hepatocellular carcinoma, the arterial blood flow was suspended. In the peripheral arteries the emulsion separated into two phases of Lp and ADM solution, forming striped pattern, and Lp embolization of the peripheral artery persisted for over 45 min. while ADM extravasated. These findings suggest that after Lp-TAE, Lp maintains an embolizing effect while ADM penetrates into the surrounding tumor tissue, and that this is an underlying mechanism for the anti-cancer effect of Lp-TAE.

Animals↗
PubMedDate not supplied

Hyaluronan preserves peritoneal membrane transport properties.

BACKGROUND: We have shown that intraperitoneal (i.p.) addition of hyaluronan (HA) in a single dwell study in rat could increase peritoneal fluid removal by decreasing the peritoneal fluid absorption rate. In this study, we investigated the impact of repeated use of HA on peritoneal membrane transport characteristics. METHODS: Twelve male Sprague-Dawley rats received a once-daily i.p. injection of 25 mL 4.25% glucose dialysis solution without (HP group, n = 6) or with 0.025% HA (HA group, n = 6) for 1 week. Forty-eight hours after the last injection, a 4-hour dwell using 25 mL 4.25% glucose dialysis solution with i.p. volume marker and frequent dialysate and blood samplings was performed in each rat as well as in rats that did not receive any injection (control group, n = 8). RESULTS: Although the i.p. volumes were significantly lower in the HP and HA groups compared to the control group, i.p. volume in the HA group was significantly higher than in the HP group. Net ultrafiltration at 4 hours was 5.6 +/- 1.3 mL, 10.2 +/- 1.8 mL, and 13.2 +/- 0.6 mL for the HP, HA, and control group, respectively. The peritoneal fluid absorption rate decreased by 45% in the HA group compared to the HP group. There was no significant difference in peritoneal fluid absorption rate between the HA and the control group. No difference was found in the direct lymphatic absorption rate between the HP and HA groups [0.010 +/- 0.003 mL/minute in the HP group and 0.011 +/- 0.004 mL/min in the HA group] although they were both higher than that of the control group (0.004 +/- 0.001 mL/min). The solute transport rates were in general significantly higher in the HP group compared to the HA and control groups, and there was no significant difference between the latter two groups, except that protein transport rate was significantly lower in the HA group compared to the control group. CONCLUSIONS: The present study suggests that (1) repeated exposure to hypertonic glucose-based dialysis solution results in increased peritoneal solute transport rates, as well as increased peritoneal fluid absorption rates; and (2) these changes, reflecting a highly permeable peritoneal membrane, were ameliorated by repeated i.p. addition of hyaluronan. The similar changes in the direct lymphatic absorption rate in rats that received daily i.p. injection of dialysis solution suggest that direct peritoneal lymphatic absorption was not influenced by hyaluronan.

Absorption↗