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Biomedical subjects

Q He

Publications and source records attributed to Q He.

At least 181 records · Page 10Linked to original sources
PubMed1998

Evaluation of lactate as a 1H nuclear magnetic resonance spectroscopy index for noninvasive prediction and early detection of tumor response to radiation therapy in EMT6 tumors.

In a recent study (Int. J. Radiat. Oncol. Biol. Phys. 36, 635-639, 1996), 1H nuclear magnetic resonance (NMR) spectroscopy was used to demonstrate significant decreases in lactate levels after gamma irradiation of radiosensitive RIF-1 tumors in vitro. For comparison, we have examined the effects of gamma radiation on lactate levels in the more radioresistant EMT6 tumor. Single-slice (5-6 mm thick) localized 1H spectra of subcutaneous RIF-1 (untreated) and EMT6 tumors (pretreatment, 24 and 48 h postirradiation with 4, 10 or 20 Gy of gamma radiation) were measured by the selective multiple quantum coherence transfer method (Sel-MQC, approximately 4 min acquisition time). Both pretreatment lactate levels and pretreatment lactate dehydrogenase (LDH) activities were found to be similar in RIF-1 and EMT6 tumors, suggesting that steady-state lactate levels are unlikely to be reliable indices for predicting response to radiation therapy. After 10 Gy gamma irradiation, EMT6 tumors showed a 21% decrease relative to pretreatment lactate levels at 48 h (1.04 +/- 0.22 to 0.82 +/- 0.16; P = 0.06); after 20 Gy a 40% decrease was observed at 48 h (1.34 +/- 0.27 to 0.81 +/- 0.10; P = 0.07). No significant changes in lactate levels were observed in control EMT6 tumors or in tumors treated with 4 Gy of gamma radiation, in contrast to changes detected previously in RIF-1 tumors, which showed a significant decrease in lactate by 48 h for both 2 and 4 Gy. The decreased effect of radiation on lactate levels in EMT6 compared to RIF-1 tumors may be attributed to the higher hypoxic fraction and lower radiosensitivity of EMT6 tumors (Int. J. Radiat. Oncol. Biol. Phys. 10, 695-712, 1984). The decrease in lactate levels did not, however, strictly reflect the extent of the response to therapy for the high dose of 20 Gy. This study together with our earlier study (Int. J. Radiat. Oncol. Biol. Phys. 36, 635-639, 1996) provides evidence to support the hypothesis that changes in steady-state tumor lactate levels may serve as sensitive early indices of tumor response to gamma radiation at doses of the order of 2 to 4 Gy.

Animals↗
PubMed1997

Modulation of actin filament behavior by GAP-43 (neuromodulin) is dependent on the phosphorylation status of serine 41, the protein kinase C site.

Synthesis of GAP-43 (also known as neuromodulin) in neurons is induced during axon growth, and high concentrations (estimated between 50 and 100 microM) accumulate in the growth cone. GAP-43 is tightly associated with the growth cone membrane skeleton, the structure that transduces extracellular guidance cues into alterations in morphology by spatially regulating polymerization of actin filaments, thereby causing directional changes in axon growth. GAP-43 cosediments with actin filaments, and its phosphorylation on serine 41 by PKC, too, is spatially regulated so that phosphorylated GAP-43 is found in areas where growth cones make productive, stable contacts with other cells. In contrast, unphosphorylated GAP-43, which binds calmodulin, is always found in parts of the growth cone that are retracting. Here we have used a cell-free assay to investigate how the phosphorylation status of GAP-43 affects its interactions with actin and show that both phosphorylated and unphosphorylated GAP-43 have different, independent effects on actin filament structure. Phosphorylated GAP-43 stabilizes long actin filaments (Kd = 161 nM), and antibodies to phosphorylated GAP-43 inhibit binding of actin to phalloidin, implying a lateral interaction with filaments. In contrast, unphosphorylated GAP-43 reduces filament length distribution (Kd = 1.2 microM) and increases the critical concentration for polymerization. Prebinding calmodulin potentiates this effect. The results show that spatially regulated post-translational modifications of GAP-43 within the growth cone, which can be regulated in response to extracellular signals, have the ability to directly influence the structure of the actin cytoskeleton.

Actins↗
PubMed1997

Delivery of liposome-sequestered hydrophobic proteins to lysosomes of normal and Batten disease cells.

We have developed a method to deliver hydrophobic proteins such as ATP synthase subunit c and ubiquitin to lysosomes of PMN (polymorphonucleocytes) and fibroblasts. ATP synthase subunit c is stored in the lysosomes of various tissues in late infantile and juvenile forms of neuronal ceriod lipofuscinosis, also called Batten disease (BD). Whether this protein storage is due to an abbreviation in protein or in the lysosomal hydrolases of BD is still not clear. We have sequestered this protein and ubiquitin in the lipid membrane of liposomes. The liposomes coated with autologous heat-aggregated IgG or apolipoprotein E when presented to the PMN and fibroblasts, respectively, accumulated in the lysosomes. Both normal and BD PMN degraded 125I-ubiquitin; the rate of degradation was, however, slower by Batten PMN. These studies indicate that a hydrophobic molecule such as subunit c can be delivered to PMN and fibroblasts, and the sequestered proteins are accessible to lysosomal hydrolases. Therefore, this technique can be used to study the metabolism of highly hydrophobic proteins by lysosomes, especially the biochemical mechanism(s) of subunit c storage in BD.

Apolipoproteins E↗
PubMed1997

The power of iterated generalized least squares (GLS) method to detect direct relationships in the analysis of correlated quantitative traits.

We examined the power of the stepwise iterated generalized least squares (GLS) method by modeling the relationship between quantitative traits and other variables using the simulated data for Problem 2A. The comparison between the generating model provided by the workshop and the results of the stepwise iterated GLS model showed that this method could be used as a first step in identifying the underlying model for genetic data. The estimated covariance matrices also provide useful information about the genetic properties of the traits.

Computer Simulation↗
PubMed1997

Safety and efficacy of angiography-guided stent placement in small native coronary arteries of < 3.0 mm in diameter.

BACKGROUND AND HYPOTHESIS: Increased operator experience, greater insight in stent deployment techniques, and improved poststent medication regimen have significantly reduced the risk of thrombotic stent closure following stent placement in large coronary arteries (> or = 3.0 mm in diameter). Whether equally favorable results are afforded by stent placement in small vessels (< 3.0 mm), however, remains unclear. Accordingly, the aim of this study was the specific examination of the risk of stent placement in small native coronary vessels, using stent deployment technique consisting of supplementary dilatations with larger balloons or high-pressure inflations, and aggressive aspirin-ticlopidine and short-term oral anticoagulation poststent therapy. METHODS: Forty-seven balloon-expandable stents (20 Gianturco-Roubin, 21 NIR, 6 Palmaz-Schatz) were successfully implanted without intravascular guidance in 45 native coronary arteries (mean reference diameter of 2.5 mm) in 44 consecutive patients (31 men, 13 men), the majority of whom (87%) were stented for the treatment of failed or suboptimal balloon angioplasty outcome. RESULTS: Successful stent placement reduced the lesion diameter stenosis from 91 +/- 9% to 3 +/- 7% (p = 0.0001). There were no early stent thrombosis or major cardiovascular events prior to hospital discharge. During a 12-month follow-up period, most patients remained symptomatically improved and no myocardial infarction, stroke, or death was observed. Five-month angiographic reassessment revealed an in-stent restenosis rate of 41%, which was higher in vessels < or = 2.5 mm in size (47 vs. 33% for vessels > 2.5 mm, p = 0.2747). CONCLUSIONS: In selected patients with small native coronary vessels < 3.0 mm in diameter, angiography-guided optimal stent placement is associated with a low risk of stent thrombosis and bleeding complications. However, the in-stent restenosis rate is high with the stents used in this study.

Angioplasty, Balloon, Coronary↗
PubMed1997

Incidence and progression of cortical and posterior subcapsular opacities: the Longitudinal Study of Cataract. The LSC Group.

OBJECTIVE: The purpose of the study is to estimate incidence and progression rates of cortical and posterior subcapsular (PSC) opacities in the Longitudinal Study of Cataract (LSC). DESIGN: An epidemiologic study of the natural history of lens opacities in a clinic-based population. PARTICIPANTS: The LSC was based on 764 participants in an earlier case-control study of lens opacities. MAIN OUTCOME MEASURES: Baseline data, collected until 1988, included color slit and retroillumination photographs. The same data were collected at follow-up visits from 1989 to 1993. The Lens Opacities Classification System III (LOCS III) was used to assess lens changes between baseline and follow-up photographs. The product-limit method was used to estimate the incidence and progression rates. RESULTS: After 5 years of follow-up, the incidence rates for developing cortical and PSC opacities were 7.7% and 4.3%, respectively. The progression rate of pre-existing cortical opacities was 16.2% after 5 years, and was twice as high as the incidence rate. The progression of pre-existing PSC opacities was much higher, and reached 55.1% after 5 years of follow-up. The incidence of newly developed cortical or PSC opacities increased with age. The incidence of PSC opacities also increased when coexisting opacities were present at baseline. CONCLUSIONS: After 5 years, 1 in every 13 patients developed new cortical opacities, and 1 in 24 developed new PSC opacities. The 5-year progression rates for cortical and PSC opacities were much higher than the incidence rates. These results can be used to estimate the rate of cortical and PSC changes in similar populations.

Aged↗
PubMed1997

Epidemiology and prevention of pertussis.

Pertussis continues to be a common cause of morbidity and mortality in unimmunized young children. In immunized populations, the disease remains endemic and epidemic. Reports of pertussis infection in older children and adults are increasing, and the data indicate that lifelong immunity from either pertussis immunization or childhood pertussis does not exist, which stresses the importance of continued booster immunization in this population. The less reactogenic acellular pertussis vaccines, which may provide protection equal to or even better than that provided by currently used whole-cell vaccines, seem to be suitable not only for primary immunization but also for boostering in all age groups. This review focuses on some recent developments in the epidemiology and prevention of pertussis infection.

Adult↗
PubMed1997

Effects of the cholecystokinin agonist pentagastrin in patients with generalized anxiety disorder.

OBJECTIVE: The anxiogenic and panicogenic effects of peripheral administration of the cholecystokinin-B receptor agonist pentagastrin and placebo were evaluated in patients with generalized anxiety disorder and normal comparison subjects. METHODS: Seven patients with generalized anxiety disorder and seven age- and sex-matched normal subjects received an intravenous bolus of placebo and pentagastrin. RESULTS: Panic attacks occurred in five patients with generalized anxiety disorder (71%) and in one normal subject (14%). Patients with generalized anxiety disorder were more likely to report more nonpanic anxiety than were normal subjects. CONCLUSIONS: Patients with generalized anxiety disorder appear to exhibit greater subjective sensitivity to pentagastrin than do normal subjects.

Anxiety Disorders↗
PubMed1997

[Ocular socket plasty with orbital implant of hydroxyapatite].

OBJECTIVE: To evaluate the clinical effect of a new surgical procedure to reconstruct socket with sclera-encapsulated hydroxyapatite after enucleation and evisceration. METHODS: Hydroxyapatite spheres were implanted primarily into auto-sclera capsule in 41 cases. Secondary implantation was performed with heterosclera-encapsulated ones in 9 cases. RESULTS: No inflammation, implant extrusion and implant dislocation occurred in 7-23 months (mean = 15.6 months) of follow-up. CONCLUSION: Satisfactory prothetic motility was obtained in all cases.

Adolescent↗
PubMed1997

[The expression of MLC2-chymase fusion gene in cultured neonatal myocardial cells].

A series of MLC2-chymase fusion genes consisting of nested 5' deletion of the chymase promoter region were constructed and transfected into primary cultured neonatal Wistar rat myocardial cells according to the modified calcium phosphate precipitation method. Total RNA Dot-blot hybridization and analysis of densitometric scanning demonstrated that MLC2 promoter is enough to direct human heart chymase gene transcription in cultured neonatal rat myocardial cells. The highest level of expression was found with the MLC2-chymase construct containing 6 bp of the chymase promoter region. More sequence of the chymase promoter region between MLC2 promoter and the ATG of chymase gene resulted in a subsequent decrease in the expression of human heart chymase gene.

Animals↗
PubMed1997

[R wave relative oscillometric blood pressure measurement].

To improve the accuracy of oscillometric blood pressure measurement, an artifact rejection method for oscillations detection called R wave-relative method was developed. It was mainly based on the correlation between ECG R wave and oscillation. Combining with identification of oscillation characteristics this method can distinguish valid signals from interference. This algorithm has been implemented in 8098 microcontroller. Its program flowchart has also been presented in this paper.

Algorithms↗
PubMed1997

Kinetics of G1/S and G2/M transition in X-irradiated ataxia-telangiectasia cells.

Cell cycle transition defects of homozygous ataxia-telangiectasia (A-T) cells were studied by using a cell cycle flow calculation method, which evaluates the dynamics of cell cycle traverse. We compared five human lymphoblastoid cell lines (LCLs) from A-T homozygotes belonging to complementation group A (ARO, BRO, RJO) and group C (CSA, BMA) with three cell lines from healthy volunteers (KK-B2, MTB, HGL). The A-T cell lines ARO and BRO were derived from the same family. Cell growth and cell cycle traverse were followed for 72 h after X-irradiation with 1-6 Gy. LCLs from healthy volunteers immediately arrested in G1 in a dose-dependent pattern, while the A-T cells did not arrest in G1 until after 12 to 24 h. The time for the appearance of the G1 arrest of these cells was independent of complementation group. The delayed G1 arrest seen in the A-T cells paralleled a lack of induction of p53, as described by others. In respect to G2 arrest, A-T cells from complementation group C (CSA, BMA) arrested to the same extent as cells from healthy volunteers. On the other hand, the other LCLs from complementation group A arrested normally, while cells from ARO and BRO did not arrest in G2. The lack of G2 arrest in BRO cells was accompanied by unchanged cdc2p34 activity. In summary, a defective radiation-induced G1 arrest seems to be present in both complementation groups of A-T homozygotes, whereas a defective G2 arrest in not always observed. The defective G1 arrest seen in A-T cells may play an important role in tumor cell survival after exposure to therapeutic irradiation.

Ataxia Telangiectasia↗
PubMed1997

[The development of a fluid percussion device for brain injury of animals].

This paper discusses a fluid percussion device for brain injury. The injury is produced by striking the cork with a pendulum dropped from a known fall height to produce transient high pressure through a fluid transfer system. Experimental results show the device has the advantages of making a controllable, repeatable, and precise injury, and it can produce different levels of injury on different animals.

Animals↗
PubMed1997

[Experimental and clinical study on the blood supply of the subdermal vascular network island flap].

A comparison study on the blood supply of the buttock subdermal vascular network island skin flap and the conventional buttock island flap was undertaken in pigs. The former was created by thinning the distal half of the conventional buttock island flap, preserving the subdermal vascular network. Evaluation was made by measurement of skin temperature, laser Doppler, fluorescence stain, ink perfusion, microangiography and transparent specimen technique. It was found that the blood supply of the subdermal vascular network island skin flap was much lower than that of the conventional island flap. The reason was thought to be the change in the blood supply after the conventional island flap was thinned. The subdermal vascular network island skin flap was composed of the axial pattern and the random pattern. Fifteen subdermal vascular network island skin flaps have been successfully transferred with vessel anastomosis in 15 patients. The average area of the thinned distal part was 49% of the flap, with the maximum of 60%.

Animals↗