Biomedical subjects

J Ge

Publications and source records attributed to J Ge.

At least 109 records · Page 6Linked to original sources

PubMed1998

In vivo tomographic assessment of the heart and blood vessels with intravascular ultrasound.

Intravascular ultrasound (IVUS) has emerged from being a research tool to becoming an intrinsic part of modern invasive cardiology mainly due to imaging micro anatomy in vivo. For the first time, it is possible to base therapeutic decisions not only on lumenograms but also on vessel wall assessment. IVUS has both diagnostic and intervention associated potential. The diagnostic strength of IVUS is its ability to describe compensatory coronary artery enlargement as a response to arteriosclerosis, to assess intermediate lesions, and to reveal occult left main stem disease and angiographically "silent" arteriosclerosis. The intervention associated potential of IVUS is the optimal device selection, i.e., rotablators in calcified lesions or atherectomy devices in large plaque burden. The effects of PTCA on vessel wall morphology can be studied in great detail and the effect on luminal gain can be assessed. Several groups have shown that the residual plaque area ("plaque burden") even after angiographically successful PTCA still lies in the range of 60%. A significant reduction in this number may influence long-term outcome after PTCA. Minimal luminal area and residual plaque area after PTCA seem to be indicators of restenosis, while the presence or absence of dissections seems to be less predictive. The main mechanism of restenosis after PTCA is vessel shrinkage, not intimal hyperplasia. Intravascular monitoring of stent expansion led to high-pressure stent deployment with a significant increase in post-procedural luminal diameters and the ability to withhold anticoagulation in patients with optimal stent deployment. In pulmonary and aortic diseases, IVUS contributed significantly to the understanding of aortic dissection and pulmonary hypertension. Additionally, with intracardiac ultrasound left and right ventricular function can be assessed. Intracardiac ultrasound has gained clinical usefulness for guiding transcatheter ablation in patients with conduction system abnormalities. In the future, integrated devices, such as balloons on IVUS catheters, steerable catheters, integrated flow and pressure transducers, tissue characterization, and 0.018" IVUS guide wire will further enhance the usefulness of IVUS.

Arteriosclerosis↗

PubMed1998

Current concepts of coronary flow reserve for clinical decision making during cardiac catheterization.

Measurements of coronary flow reserve, once used only for research, have gained wide acceptance as an additional diagnostic approach in the decision-making process of diagnostic cardiac catheterization and coronary interventions. Apart from the noninvasive determination of coronary flow reserve, intracoronary Doppler flow wires have facilitated decision making in the catheterization laboratory. Different techniques, unstandardized procedures, and data from uncomparable patient populations have remained a confounding factor. This review examines current concepts of coronary flow reserve as well as methodologic considerations and pitfalls. Applications of coronary flow reserve for periinterventional assessment are evaluated on the background of practical guidance. According to a detailed examination of arterial structure and function, a normal coronary flow reserve exceeds a value of 3.0. Values below 3.0 suggest involvement of microvascular disease caused by functional or structural alterations. The influences of various factors such as age, hemodynamics, hypercholesterolemia, hypertrophy, hypertension, syndrome X, and coronary artery disease are discussed in relation to the effect on coronary flow reserve. From available information, measurements of coronary flow reserve are an adjunct to current interventional technology to optimize individual patient care. Further efforts should be undertaken to incorporate these new methods into our routine clinical decision making.

Blood Flow Velocity↗

PubMed1998

Intravascular ultrasound (IVUS) examination reverses therapeutic decision from percutaneous intervention to a surgical approach in patients with alterations of the left main stem.

Intravascular ultrasound (IVUS) represents a new method to assess vessel lumen and wall morphology. To prospectively evaluate the usefulness of IVUS for further therapeutic decisions in left main stem (LM) lesions with unclear angiographic definition, this study was launched. We studied 56 patients with significant stenosis of the LAD and/or LCX arteries and questionable LM morphology. 30-MHz IVUS catheters with 2.9 or 3.2 F outer diameters were used. A significant luminal reduction of the left main stem was defined as an area stenosis greater than 50% or a minimal luminal diameter smaller than 3 mm as determined by IVUS. 36 of 56 patients (61%) fulfilled these criteria. Additionally, 12 patients showed a ruptured plaque within the LM. 30 of these 36 patients were originally thought to be candidates for angioplasty. After positive IVUS 34 of these 36 patients were sent to surgery. No perioperative ischemic complications occurred. In angiographically unclear left main stem findings. IVUS establishes a definitive diagnosis. After IVUS confirmation of significant left main stem pathology operative management should be the preferred approach as compared to transluminal coronary interventions. However, prospective randomized studies are needed to define the most efficient approach.

Angioplasty, Balloon, Coronary↗

PubMed1998

[A clinical study on reducing immunologic rejection in combining corneal lamellar autografting with allografting].

OBJECTIVE: To reduce the rate of immunologic rejection, corneal lamellar autografting with allografting were combined, making immune cells less attack on allograft. METHODS: The pterygium having encroached upon the pupillary area was removed surgically, and the combination of autograft with allograft was transplanted on the peripheral and central cornea in 23 cases (24 eyes). The control group of 13 cases (13 eyes) was established in which the pterygium and dermoids were removed, and lamellar allografts were transplanted. The rate of rejection and their effects were compared. RESULTS: The rate of transparent autograft and allograft was 100%, no rejection and recurrence of pterygium occurred in any case in the combined group, while in the control group, the rejection rate was 30.8% and recurrence rate, 20.0%. CONCLUSION: The combination of lamellar autografting with allografting can reduce the rate of rejection and recurrence of pterygium.

Adult↗

PubMed1998

[Expression of bcl-2 gene in human trabecular cells induced by dexamethasone].

PURPOSE: To investigate the influence of dexamethasone on expression of bcl-2 gene in human trabecular cells. METHODS: The trabecular specimens from human eyes were cultured in vitro and the cultured cells of the third generation on slides were immersed in culture solution containing 10(-7) M dexamethasone for 6 hours, 12 hours and 24 hours respectively. The expression of bcl-2 gene was studied with LSAB. RESULTS: The positive cells of the bcl-2 protein could be identified after dexamethasone effected for 6 hours and the positive cell increased with time going on. CONCLUSION: The expression of bcl-2 gene can be induced by dexamethasone, it may be related with glaucomatic pathogenesis.

Apoptosis↗

PubMed1998

[The significance of combination of electrophysiology and automated perimetry tests on the early diagnosis of primary open angle glaucoma].

OBJECTIVE: The study was designed to analyze the relationship among the three electrophysiological tests and visual fields in primary open angle glaucoma (POAG) in order to find some more sensitive and specific parameters in earlier and early diagnosis of patients with POAG. METHODS: Thirty-six(70 eyes) patients with POAG, 8(12 eyes) glaucoma suspects and 30 (60 eyes) normal subjects underwent pattern electroretinogram (PERG), oscillatory potentials (OPs), pattern visual evoked potentials (PVEP) and Humphery automated perimetry tests respectively. RESULTS: The abnormal rate of PERG was the highest among the three electrophysiological tests in the glaucoma suspects and those of PERG and automated perimetry results were higher than others after early stage. In the correlation analysis of all objects, the amplitude of PERG had negative correlated with IOP and visual indices, but no correlation with C/D and VA. OPs had negative correlated with C/D, and no correlation with visual fields indices, intraocular pressure (IOP) and visual acuity (VA). The latency of PVEP had positive correlation with visual fields indices and C/D, but no correlation with IOP. CONCLUSION: Statistical result showed that different parameters could be selected according to different appearance of POAG. In the earlier stage before visual field defects could be found, PERG would be a more sensitive indicator if IOP were high; once C/D was abnormal, OPs and PVEP would be the better signs even though IOP was normal. PERG and Humphery automated perimetry were very useful indicators after early stage. It was significant in combination of many visual function tests on earlier or early diagnosis of POAG.

Electrophysiology↗

PubMed1998

[A quantitative measurement of retinal nerve fiber layer thickness by optical coherence tomography in normal Chinese people].

PURPOSE: To measure retinal nerve fiber layer(RNFL) thickness in normal Chinese people for the use of early diagnosis in glaucomatous patients. METHODS: Optical Coherence Tomography(OCT) was used in 111 eyes of 77 Subjects to create cylindrical cross sections of the RNFL around the optic nerve head with scan diameter of 3.46 mm. The differences in RNFL thickness were analyzed with age, sex, either eye. RESULTS: We found a decrease in RNFL thickness with aging especially in the superior quadrant(P < 0.05), but there weren't significant difference between right and left eyes, neither the sex(P > 0.05). The Mean RNFL thickness of different ages(mean +/- s) was as following: the superior quadrant 128.00 +/- 10.31-149.00 +/- 13.17, the inferior quadrant 132.95 +/- 9.54-142.33 +/- 10.60, the overall mean RNFL thickness 109.00 +/- 4.72-114.28 +/- 7.98 microns. CONCLUSION: The preliminary study showed that neither sex nor either eye were associated with significant differences in RNFL thickness. It is necessary to define the normative value by age group on a larger scale.

Adolescent↗

PubMed1998

Peripheral nerve and transgene cells transplantation in the treatment of experimental neuropathy of SD rats.

PURPOSE: To observe whether optic nerve can regenerate by peripheral nerve transplantation and GDNF gene transfer. METHODS: Optic nerve was transected about 2 mm posterior to the eye to establish experimental models of optic neuropathy. Sciatic nerve was sutured to the sheath of injury optic nerve by a 10-0 nylon, pcDNA3-GDNF was smeared to the joint and injected to the vitreous cavity. The regenerated retinal ganglion cells axons were observed by HRP. The retina and optic nerve were observed by pathohistological methods. RESULTS: Some retinal ganglion cells with regenerated axons could be seen a week after transplantation with large cell bodies. The cells could be identified by HRP. The regenerated nerve fibers grew to the transplanted sciatic nerve. Then the number of retinal ganglion cells with regenerated axons increased with time going. Only a few regenerated retinal ganglion cells could be seen two months after transplantation. The large retinal ganglion cells were seen to have plenty of cytoplasms and be in an active state under electron microscope. Some nerve fibers could be seen in the joint. Sciatic nerve transplantation combined with GDNF gene therapy could increase the amount of retinal ganglion cells with regenerated axons compared with those without GDNF transgene. CONCLUSIONS: Optic nerve could regenerate by peripheral nerve transplantation and GDNF gene transfer.

Animals↗

PubMed1998

The study on culture and ultrastructure of glaucomatous trabecular cells in vitro.

PURPOSE: To establish the culture system of human glaucomatous trabecular cells in vitro and study their ultrastructures. METHODS: The trabecular specimens from trabeculectomy were cultured in vitro and passaged 3 times, then identified. Moreover, the glaucomatous cells were observed with electron microscope while compared with the normal ones. RESULTS: Cultured human glaucomatous trabecular cells were obtained. The ultrastructure of the cells showed the decrease in vilious project, coated vesicle and lysosomal inclusion. CONCLUSION: The establishment of human glaucomatous trabecular cells culture in vitro made the culture system more perfect. The morphologic changes might be related to the abnormal functions of human trabecular meshwork cells.

Cell Division↗

PubMed1998

Hemodynamics of ophthalmic artery and central retinal artery and correlation with other factors in patients with primary open angle glaucoma.

OBJECTIVE: To investigate the hemodynamics of ophthalmic artery (OA) and central retinal artery (CRA) in patients with primary open angle glaucoma(POAG) and analyse the correlation between hemodynamics of OA and CRA and other factors. METHODS: The hemodynamics of OA and CRA in normal persons (102 eyes) and glaucomatous patients (102 eyes) were measured by Colour Doppler Image (CDI). The linear correlation analysis was made between OA and CRA about each of the following parameters: the peak systolic flow velocity (Vmax), the end diastolic velocity (Vmin). The multiple stepwise regression analysis was taken to investigate the correlation between each of the following hemodynamics of OA and CRA: Vmax and Vmin in 74 eyes with POAG and each of the following related factors in hemorrheology: whole blood apparent viscosity at low, medium and high shear rate, plasma viscosity and hematocrit. The multiple linear regression was applied to investigate the correlation between each of the following hemodynamics of OA and CRA: Vmax and Vmin in 69 eyes with POAG and each of the following blood vessel filling time: the arm-retinal artery (A-AT) and retinal artery-venous (A-VT) of the fundus fluorescein angiography(FFA). RESULTS: The Vmax, Vmin and time-averaged maximum velocity (Vmean) of OA and CRA in patients with POAG were lower than those in normal persons, but the resistance index (RI) of OA and CRA was higher than those in normal. There was a positive correlation between OA and CRA in Vmin, but a negative correlation between Vmin of OA and plasma viscosity. The whole blood apparent viscosity at low shear rate was clodely related to Vmax and Vmin of CRA. Also there was a negative correlation between Vmax of CRA and A-AT of the FFA. CONCLUSION: There was abnormal hemodynamics, which is influenced by blood viscosity, of OA and CRA in patients with POAG. Abnormal hemodynamics can affect the blood supply to optic disc and retina in POAG.

Blood Flow Velocity↗

PubMed1998

Characterization of glucocorticoid receptor on lymphocytes in Chinese patients with glucocorticoid-induced glaucoma.

PURPOSE: We studied the pathogenesis of glucocorticoid-induced glucoma (GIG) through characterization of glucocorticoid receptor (GR) on lymphocytes in Chinese patients with GIG. METHODS: By radioligand receptor binding followed by Scatchard analysis, the specific binding sites were characterized and quantitated for glucocorticoid receptors on peripheral blood lymphocytes obtained from patients with GIG and the control group. RESULTS: The binding sites we detected were as follows: 12.7 +/- 1.47 x 10(3) receptors per cell with a KD of 3.02 +/- 0.62 nmol/L in patients with GIG, 7.26 +/- 0.45 x 10(3) receptors per cell with a KD of 3.03 +/- 0.56 nmol/L in the control group. The statistical difference of receptors per cell is significant between two groups (p < 0.05), patients with GIG having more GR binding sites, while the difference of Kd is not significant (p > 0.05). CONCLUSION: The preliminary findings suggest that patients with GIG are more sensitive to glucocorticoid and the increase of binding sites of GR may be the receptor and molecular basis of the pathogenesis of GIG.

Adolescent↗

PubMed1998

[The preliminary experiment of gene transfer into cultured rat retinal neural cells].

PURPOSE: To investigate the possibility of gene transfer into retina neural cells. METHODS: pcDNA3-LacZ and pcDNA3-GDNF were transferred into rat retinal neural cells with cationic lipofectin. The gene transfer and expression of GDNF were detected by means of RT-PCR and SDS-PAGE. RESULTS: pcDNA3-LacZ and pcDNA3-GDNF could be transferred into retinal neural cells and the expressive product of GDNF gene, a 32 KD protein band, was detected. CONCLUSION: The preliminary results suggest that LacZ gene could be a marker to identify gene transfer into the target tissue and cells; GDNF gene could be transferred into cultured retinal neural cells of SD rats, and express 32 KD protein.

Animals↗

PubMed1998

[The study on the culture, freezing preservation and resuscitation of human trabecular cells in vitro].

PURPOSE: To establish the culture of human trabecular cells in vitro and study the freezing preservation and resuscitation. METHODS: The trabecular specimens from human eyes were cultured in vitro and passaged 3 times, then the cultured cells were frozen and preserved. The frozen cells were resuscitated after one week, two weeks, one month and two months. RESULTS: Cultured human trabecular cells were obtained. The frozen cells were resuscitated successfully. All of the resuscitated rates were more than 90%. CONCLUSION: The human trabecular cells were cultured in vitro successfully, they can also be frozen and resuscitated, which will be helpful to the establishment of cDNA library and the screening of associated glaucomatous genes.

Cell Division↗

PubMed1998

[The application of antisense technology in ophthalmology].

The research of gene regulation become more and more important with the advancement of the technology of molecular biology and gene study. Antisense molecules can regulate and modify gene expression. By using antisense technology, antisense RNA or artificial antisense oligonucleotides can be made to inhibit or block the transcription and translation of genes. These molecules are highly specific in gene regulation. The application of antisense technology in ophthalmology is introduced briefly in the review. This may be helpful to the studies in ophthalmic research field.

DNA, Antisense↗

PubMed1997

Coronary artery calcium in acute coronary syndromes: a comparative study of electron-beam computed tomography, coronary angiography, and intracoronary ultrasound in survivors of acute myocardial infarction and unstable angina.

BACKGROUND: Quantification of coronary artery calcified plaques by electron-beam CT (EBCT) may predict cardiovascular events. However, whereas advanced coronary atherosclerotic plaques can be identified, mildly stenotic lipid-rich (soft) plaques may be difficult to detect. The value of EBCT in a subgroup of patients has therefore been questioned. To investigate this, we evaluated patients with acute coronary syndromes by EBCT and compared the results with coronary angiography and, in patients with an indeterminate angiogram, intracoronary ultrasound (ICUS). METHODS AND RESULTS: EBCT was performed in 118 consecutive patients (57+/-11 years of age) with previous myocardial infarction (n=101) or unstable angina (n=17). A standard protocol requiring a CT density >130 Hounsfield units in an area > or =1.03 mm2 was used for the definition of coronary artery calcium. We found that 110 patients had moderate to severe coronary artery disease by coronary angiography, and 8 had either mildly stenotic plaques at a single site (4 patients, confirmed by ICUS) or nonatherosclerotic causes of the unstable coronary syndrome (4 patients). One hundred and five of the 110 patients (96%) with moderate to severe angiographic disease but only 1 of the 8 other patients (13%) had a positive EBCT. Patients with acute coronary syndromes and negative EBCTs were significantly younger than patients with positive EBCTs (46+/-12 versus 58+/-10 years, P<.001), and a higher percentage was actively smoking (100% of the smokers versus 46%, P<.05). CONCLUSIONS: The vast majority of patients with acute coronary syndromes and at least moderate angiographic disease have identifiable coronary calcium by EBCT. Those patients with negative EBCTs have minimal or no atherosclerotic plaque formation. They are younger and tend to be active cigarette smokers.

Acute Disease↗

PubMed1997

Distribution of S(-)-zacopride-insensitive [125I]R(+)-zacopride binding sites in the rat brain and peripheral tissues.

Increasing evidence indicates that the 5-HT3 receptor antagonist R(+)-zacopride labels an additional site in brain tissue that is not sensitive to 5-HT (non-5-HT R(+)-zacopride site, R(+)-site). Since the levels of R(+)-sites in the brain are relatively low, the present studies explored the use of [125I]R(+)-zacopride to label the R(+)-site; the incorporation of an [125I] atom considerably increasing the specific activity of the radioligand relative to [3H]R(+)-zacopride that has been utilised previously. Competition experiments with [125I]R(+)-zacopride (1.0 nM) binding to rat whole brain homogenates, in the presence of the 5-HT3 receptor antagonist granisetron (1.0 microM), identified that R(+)-zacopride and prazosin bound to two sites (pIC50: 7.59 and 5.28, respectively, for R(+)-zacopride; 6.75 and 4.42, respectively, for prazosin) whereas S(-)-zacopride and mianserin possessed relatively low affinity (pIC50: 4.37 and 3.80, respectively) while (-)sulpiride and 5-HT failed to compete for [125I]R(+)-zacopride binding at concentrations up to 10 microM. Autoradiographic radioligand binding studies using [125I]R(+)-zacopride (0.5 nM) identified a heterogeneous distribution of specific binding sites (defined by unlabelled R(+)-zacopride, 1.0 microM) throughout the rat brain. In the presence of a saturating concentration of granisetron (1.0 microM), highest levels of specific [125I]R(+)-zacopride, binding sites (defined by R(+)-zacopride, 1.0 microM; R(+)-site), were detected in the olfactory tubercle, thalamus, corpus callosum, colliculus, dorsal and median raphe nucleus, spinal cord and the pons (8.0-13.0 fmol/mg). Moderate densities of R(+)-sites were located in the striatum, nucleus accumbens, substantia nigra, ventral tegmental area, globus pallidus, septal nuclei, frontal cortex and cerebellum (2.0-7.9 fmol/mg). In the hippocampus, amygdala and cortical areas. R(+)-site levels were low but detectable (0.1-1.9 fmol/mg). [125I]R(+)-zacopride labelled R(+)-sites were also detected in some rat peripheral tissues, for instance kidney cortex, adrenal gland and liver (2.4-6.8 fmol/mg). The present results indicate that specific non-5-HT [125I]R(+)-zacopride sites are heterogeneously distributed throughout the rat brain and are expressed in various peripheral tissues.

Animals↗

PubMed1997

High-volume nonionic dimeric contrast medium: first experiences during complex coronary interventions.

Interventional cardiology is a rapidly developing field of medicine with annually increasing numbers of coronary interventions. Especially through the development of alternative techniques for coronary angioplasty, new indications have been found and more difficult lesions are tackled. Inevitably, such complex interventions are time-consuming and require high amounts of contrast medium. Newer, mostly nonionic agents have been developed with improved tolerability as well as fewer cardiac and renal side effects due to their nonionic, hydrophilic structure, and their osmolality isotonic to plasma. This study sought to investigate the effects of high-volume nonionic, dimeric contrast medium during coronary interventions with special emphasis on renal and hemodynamic side effects during routine hospital stays. Retrospectively, 25 consecutive patients (age 56 +/- 10 yr) with normal renal and cardiac function receiving > 500 ml of the nonionic dimeric contrast medium iodixanol during complex coronary interventions were analyzed. The analysis was based on serum creatinine levels 1 day before and 2 days after contrast medium administration for the monitoring of renal function. Additionally, heart rate and left ventricular pressures were evaluated before and after left ventricular angiography. Mean serum creatinine rose from 0.9 +/- 0.2 mg/dl to 1.1 +/- 0.2 mg/dl (P < 0.05) after 2 days of coronary intervention. Heart rate, left ventricular systolic pressure, and left ventricular end-diastolic pressure did not change significantly. No major side effects were encountered in the short follow-up period of 2 days. Based on this retrospective analysis, high-volume nonionic, dimeric contrast medium administration in patients without preexisting renal insufficiency is associated with little impairment of renal function, and has only minor hemodynamic and general side effects. Iodixanol 320 mg I/ml is well-tolerated and effective for the use of cardioangiography. Given the limitations of this retrospective analysis, future prospective studies should systematically address the effects of high-volume contrast medium administration in otherwise healthy patients as well as in high-risk patients undergoing coronary interventions.

Aged↗

PubMed1997

[Laser angioplasty and recanalization].

Percutaneous transluminal coronary balloon angioplasty (PTCA) still is the most frequently applied interventional technique for treatment of coronary artery disease. Plastic deformation of the obstructive plaque with creation of splits, intimal tears and dissections is the main mechanism of PTCA for lumen widening. As a result, acute complications due to flow limiting dissections and acute vessel closure can unpredictably occur resulting in myocardial infarction, urgent bypass surgery and death. Furthermore, long-term success of PTCA is limited by restenosis. In order to overcome these limitations of PTCA, alternative interventional techniques were developed, which instead of deforming the obstructive plaque ablate this tissue. These techniques include high and low speed rotational angioplasty, directional atherectomy, the transluminal extraction catheter, ultrasound angioplasty and laser (Light Amplification by Stimulated Emission of Radiation) angioplasty. 308 nm XeCl excimer laser angioplasty today is the laser technique of choice for clinical application. This pulsed laser requires direct contact to the obstructive plaque. It creates fast (< 200 microseconds) expanding gas bubbles which induce plaque ablation. Main indications for 308 nm XeCl excimer laser angioplasty are diffuse and long coronary lesions and total coronary occlusions. Despite promising initial results this technique showed no better acute and long-term results in comparison to PTCA for the treatment of these types of lesions ("Amsterdam-Rotterdam" Study, "Excimer Rotational Balloon Angioplasty Comparison" Study). As a result, this interventional technique was rarely applied for patient treatment. More recently, the concept of plaque ablation by 308 nm XeCl excimer laser angioplasty was renewed for the treatment of in-stent restenosis. This indication is being investigated in the "Laser Angioplasty of Restenosed Stents" trial. First results document the practicability and safety of this approach. Long-term results are awaited. With ongoing miniaturization, laser guidewires were developed for the recanalization of chronic total occlusions. The randomized multicenter "Total Occlusion Trial with Angioplasty assisted by Laser guidewire "Study documented a success rate of laser wire recanalization in up to 66% in contrast to 47.5% for mechanical wires only. Long-term results are still awaited. Technical and procedural progress including saline flush during laser application, homogeneous light distribution and the concept of smooth laser ablation is pushed foreward to make excimer laser angioplasty safer, more predictable and more effective.

Angioplasty, Balloon, Coronary↗