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Biomedical subjects

Q Hu

Publications and source records attributed to Q Hu.

At least 127 records · Page 7Linked to original sources
PubMed1996

Comparing techniques of measuring tumor hypoxia in different murine tumors: Eppendorf pO2 Histograph, [3H]misonidazole binding and paired survival assay.

Using five transplantable murine tumors (SCC-VII, B16F1, KHT-C, KHT-LP1, RIF-1), measurements of tumor hypoxia have been made with two techniques which have the potential to be used for assessing oxygenation in human tumors (the Eppendorf pO2 Histograph and binding of [3H]misonidazole) and have been compared with an established radiobiological technique, the paired survival assay. There were significant differences in the pO2 measurements made in individual tumors both within and between the five different tumor types. Significant differences between the tumor types were also found for the [3H]misonidazole binding. A correlation was observed between the mean values of the hypoxic proportion as measured by the paired survival assay and the mean binding of [3H]misonidazole as measured by both tumor activity in dpm/100 mg tissue (r = 0.94, P = 0.02) and the tumor-to-muscle activity ratio (r = 0.87, P = 0.06). No biologically significant correlation was seen between the mean values of the hypoxic proportion from anesthetized mice as measured by the paired survival assay (range 20-58%) and the pooled Eppendorf pO2 Histograph measurements made on groups of tumors. These results with the Eppendorf pO2 Histograph are similar to those reported by others. When both Eppendorf pO2 Histograph measurements and paired survival measurements were made on the same individual KHT-C tumors, it was again found that there was no correlation between the two measurements of hypoxia.

Animals↗
PubMed1996

Radiosensitivity, apoptosis and repair of DNA double-strand breaks in radiation-sensitive Chinese hamster ovary cell mutants treated at different dose rates.

The relationship of cell survival to induction and repair of DNA double-strand breaks (DSBs), as assessed by the neutral comet assay, was studied in two pairs of CHO cell lines, repair-deficient mutants xrs-5-11 and V3, and their respective parent lines K-1 and AA8, treated at two dose rates, 10.5 and 0.09 Gy/min. A marked difference in cell survival after irradiation was found between each pair of lines. For initial DNA damage, there was a significant difference between each pair of lines after the low-dose-rate treatment but not with high-dose-rate irradiation. Initial DSBs were dependent on dose at both dose rates. When residual damage at 2 h after irradiation was assessed, the 5-11 cells showed significantly more damage than K-1 cells after both high- and low-dose-rate irradiation. The V3 cells also showed more residual damage than the AA8 cells, but this difference was significant only after high-dose-rate irradiation. The results indicate that low-dose-rate irradiation can differentiate better between the DSB rejoining capacity of the sensitive and resistant cells and are consistent with the idea that it is the slow component of repair of DSBs which is different between them. Further studies with 5-11 and K-1 cells showed that radiation-induced apoptosis was dependent on dose, with a higher fraction of apoptotic cells in 5-11 than in K-1 cells after exposure to a given high-dose-rate radiation dose. However, the levels and time course of induction of apoptosis were similar for doses which gave equal levels of clonogenic survival. Radiation treatment was found to delay the progression of 5-11 and K-1 cells through the cell cycle to the same extent, with accumulation of cells in S phase and G2 phase, at 4 and 12 h after irradiation, respectively. There was no evidence for a G1-phase arrest. Western blotting revealed that there were higher levels of p53 and Waf1 protein in nonirradiated 5-11 than in K-1 cells, and that a dose of 5 Gy of high-dose-rate radiation up-regulated the expression of p53 and Waf1 protein to similar levels in both cell lines. There was no change in levels of the Gadd45 and Bcl2 proteins in either cell line after irradiation. These results suggest that the accumulation of p53 and Waf1 protein does not cause early G1-phase arrest in these cells.

Animals↗
PubMed1996

Transposition of flexor pollicis brevis muscle for reconstruction of thumb opposition. Anatomical study and clinical application.

OBJECTIVE: Based on the anatomical study and clinical trial of transposition of the flexor pollicis brevis muscle (M. f. p.b.) for the reconstruction of thumb opposition, we suggested a new method for the treatment of irreparable median nerve injury which causes paralysis of the opponens pollicis and the abductor pollicis brevis muscles (M.a.p.b) and leads to loss of thumb opposition. MATERIAL AND METHODS: Anatomical study and biomechanic analysis were performed on 20 cadaveric hands and 8 patients who had been treated and followed up on an average for 12 months. RESULTS: The M.f.p.b. overlaps the M.a.p.b. for about half of its width at the muscle origins and the overlapping reduced to about 1/3 of the width at the muscle belley level. The M.f.p.b. chiefly inserted on the palmar aspect of the base of proximal phalanx. The M.a.p.b. primarily was inserted on the radial side of the first metacarpophalangeal(MP) joint, and the M.f.p.b. was entirely innervated by the deep branch of the ulnar nerve. In an attempt to increase the angle between longitudinal force lines of these two muscles for 7 degrees-9 degrees, we transferred the insertion of the M.f.p.b. to the radial side of the MP joint, so that it gives this muscle the function of opposition. Eight patients were treated and followed up on an average for 12 months. All had fine functional results. CONCLUSIONS: This method is effective, and least traumatic, and does not need transposition of another tendon.

Adult↗
PubMed1996

[Evaluation of different pathologic methods for the diagnosis of sarcoidosis].

The biopsy of different tissues were reviewed in 34 patients with intrathoracic sarcoidosis for determining their value on the diagnosis of sarcoidosis. Biopsy of different tissues was performed by routine method. The transbronchial lung biopsy (TBLB) was done under bronchoscope. The diagnosis was confirmed in 90.9% (10/11) of the biopsies of periphery lymph nodes, 75.0% (3/4) of the scalene nodes' biopsies, 68.4% (13/19) of the transbronchial lung biopsies and 70.6% (12/17) of the bronchial mucosal biopsies (BMB) through fibroptic bronchoscopy. Only 4 in 7 patients were diagnosed through skin biopsies. Kveim test was positive in 5 of 6 patients. Both TBLB and BMB were undertaken in 16 patients. The coincidence ratio between them was as high as 81.3%. The total diagnostic percentage through bronchoscopy was 87.5%. Significant differences were found between the results of TBLB or SMB before and after 1990 (P < 0.05 and 0.01 separately proved by chi 2 test). After 1990, 85.7% of TBLBs and 92.3% of BMBs were diagnostic. According to the study, TBLB and BMB were the methods that were repeatable, highly diagnostic, less invasive, and mutually compensable. They were superior over the other methods in the diagnosis of sarcoidosis. The diagnostic yield could be elevated by the accumulation of experiences and the improvement of techniques. They deserved recommending in the clinical practice.

Adult↗
PubMed1996

[The influence of electroacupuncture with different frequencies on the discharges of neurons in rostral ventromedial medulla on rats].

The experiments were carried out on rats, anesthetized with urethan and paralyed with tubocuraine. Stainless steel needles were inserted into bilateral "Zusanli" points. The unit discharges of RVM neurons were recorded extracellalarly by microelectrode. The searching of nociceptive neurons and processing of data were operated automatically by a real time control system. The results were as follow: 1. The pain response of excitatory neurons could be inhibited by 2 Hz EA (n = 15/22, P < 0.01), the mean inhibition rate was 32.40%. 2. The inhibitory effects of 2 Hz were completely blocked by naloxone pretreated (n = 5/5, P < 0.01). 3. The pain response of excitatory neurons could be inhibited by 10 Hz EA(n = 10/13, P < 0.01), the mean inhibition rate was 49.06%. 4. The inhibitory effects of 10 Hz EA were partially blocked by naloxone pretreated (n = 5/5, P < 0.01). 5. Both 2 Hz and 10 Hz EA could enhance the spontaneous discharges of excitatory neurons in RVM, and the percentage of change in the frequency was 62.45% and 112.02% respectively. 6. Neither 2 Hz nor 10 Hz EA could obviously influence the spontaneous activity of inhibitory neurons in RVM. The results suggest that both 2 Hz and 10 Hz EA could activate excitatory neurons in RVM, which may suppress nociceptive transmission via opioid mechanism.

Acupuncture Analgesia↗
PubMed1995

Liposome clearance from blood: different animal species have different mechanisms.

The kinetics of blood clearance and the mechanisms of liposome uptake by the reticuloendothelial system (RES) were compared in two animal species (mice and rats). By employing an in situ liver perfusion technique with selected liposome compositions (PC/Chol, PC/Cho/PS, PC/Chol/GM1 and PC/Chol/PEG5000-PE), we demonstrated that liposomes with same lipid composition exhibited different blood circulation half-lives in different animal species. Although liver is the major organ responsible for the clearance of liposomes from blood in both animal species, the specific mechanisms differ. In mice, liposome uptake by the liver did not involve specific serum opsonins. In contrast, liposome uptake by the rat liver was strongly dependent on serum opsonins. Further, the activity of serum opsonins for a given liposome composition differed among animal species. Human serum exhibited higher opsonin activities for PC/Chol and PC/Chol/GM1 liposomes than bovine sera, while rat serum displayed a high opsonizing activity for GM1 liposomes and none for liposomes composed of PC and Chol. The opsonin activity of human serum could be removed or decreased by treatment with EGTA/Mg2+, EDTA or cobra venom factor, suggesting that the activity is likely due to complement components. It is likely that C3 of the human complement system plays an important role in mediating the uptake of liposomes by the liver.

Animals↗
PubMed1995

Ras-dependent induction of cellular responses by constitutively active phosphatidylinositol-3 kinase.

Phosphatidylinositol (Pl)-3 kinase is one of many enzymes stimulated by growth factors. A constitutively activated mutant, p110, that functions independently of growth factor stimulation was constructed to determine the specific responses regulated by Pl-3 kinase. The p110 protein exhibited high specific activity as a Pl-3 kinase and as a protein kinase. Expression of p110 in NIH 3T3 cells induced transcription from the fos promoter. Co-expression of dominant negative Ras blocked this response. When expressed in Xenopus laevis oocytes, p110 increased the amount of guanosine 5'-triphosphate-bound Ras, caused activation of the Ras effector Raf-1, and induced Ras-dependent oocyte maturation. These findings show that Pl-3 kinase can stimulate diverse Ras-dependent cellular processes, including oocyte maturation and fos transcription.

3T3 Cells↗
PubMed1995

Identification of Rlk, a novel protein tyrosine kinase with predominant expression in the T cell lineage.

The control of phosphorylation by protein tyrosine kinases represents an important regulatory mechanism in T cell growth, function, and differentiation. We have identified a 62-kDa murine protein tyrosine kinase predominantly expressed within the T cell lineage, which we have termed Rlk (for Resting lymphocyte kinase). rlk mRNA was found to be expressed in the fetal thymus as early as day 13 of embryonic development as well as in adult thymus and mature resting peripheral T cells. The sequence of rlk showed that it is most closely related to the subfamily of cytoplasmic tyrosine kinases that includes the Btk, Itk, and Tec proteins. However, Rlk differs from these kinases by virtue of its unique aminoterminal domain, which lacks a region of pleckstrin homology common to the other members of this protein subfamily. Examination of rlk abundance within different T cell subpopulations revealed preferential expression in Th1 relative to Th2 T cell clones, suggesting a possible role in signal transduction pathways that selectively regulate cytokine production in mature CD4+ T cell subsets. Rlk thus represents a novel cytoplasmic tyrosine kinase with potential functions in intrathymic T cell development and mature T cell signaling.

Amino Acid Sequence↗
PubMed1995

Binding of NCK to SOS and activation of ras-dependent gene expression.

NCK, an SH2- and SH3 domain-containing protein, becomes phosphorylated and associated with tyrosine kinase receptors upon growth factor stimulation. The sequence of NCK suggests that NCK functions as a linker between receptors and a downstream signaling molecule. To determine if NCK can mediate growth factor-stimulated responses, we measured the ability of NCK to activate the fos promoter. We found that in NIH 3T3 cells, NCK strongly activates this promoter. The effect of NCK on the fos promoter is enhanced by c-ras and blocked by dominant negative ras. We also found that NCK binds directly to the guanine nucleotide exchange factor SOS. This interaction is mediated by the SH3 domains of NCK. These findings suggest that NCK can regulate p21ras-dependent gene transcription through interaction with SOS protein.

3T3 Cells↗
PubMed1995

c-KIT expression enhances the leukemogenic potential of 32D cells.

The growth of human leukemic cells in culture and in vivo is dependent upon the presence of hematopoietic growth factors. Most populations of human leukemic acute myeloblastic leukemia (AML) cells express c-Kit on their surface and respond to Kit ligand (KL) in culture. To determine if this interaction was of potential significance in vivo we used a mouse model system. 32D cells, a murine IL-3-dependent myeloid cell line, were rendered KL responsive by transfection of the murine c-Kit. After injection of 32D or 32D-Kit cells into syngeneic hosts, animals bearing 32D-Kit cells, but not 32D cells, became moribund and were killed. These animals had circulating leukemic blast cells, infiltration of bone marrow, spleen, brain, liver, lung, and kidney. Cells recovered from some of the animals continued to be dependent upon IL-3 or KL for growth while in other cases the cells were factor independent. This model illustrates that the constitutive expression of c-Kit enhances the leukemic potential of 32D cells. The model will be useful for studying the progression of leukemia in vivo and testing whether interruption of the interaction of Kit and KL can affect the growth of leukemic cells.

Amino Acid Sequence↗
PubMed1995

Detection of hypoxic fractions in murine tumors by comet assay: comparison with other techniques.

The alkaline comet assay was used to detect the hypoxic fractions of murine tumors. A total of four tumor types were tested using needle aspiration biopsies taken immediately after a radiation dose of 15 Gy. Initial studies confirmed that the normalized tail moment, a parameter reflecting single-strand DNA breaks induced by the radiation, was linearly related to radiation dose. Further, it was shown that for a mixed population (1:1) of cells irradiated under air-breathing or hypoxic conditions, the histogram of normal tail moment values obtained from analyzing 400 cells in the population had a double peak which, when fitted with two Gaussian distributions, gave a good estimate of the proportion of the two subpopulations. For the four tumor types, the means of the calculated hypoxic fractions from four or five individual tumors were 0.15 +/- 0.04 for B16F1, 0.08 +/- 0.04 for KHT-LP1, 0.17 +/- 0.04 for RIF-1 and 0.14 +/- 0.01 for SCCVII. Analysis of variance showed that the hypoxic fraction in KHT-LP1 tumors is significantly lower than those of the other three tumors (P = 0.026) but that there is no significant difference in hypoxic fraction between B16F1, RIF-1 and SCCVII tumors (P = 0.574). Results from multiple samples taken from each of five RIF-1 tumors showed that the intertumor heterogeneity of hypoxic fractions was greater than that within the same tumor. The mean hypoxic fraction obtained using the comet assay for the four tumor types was compared with the hypoxic fraction determined by the clonogenic assay, or median pO2 values, or [3H]misonidazole binding in the same tumor types.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Culture of Streptomyces and purification of streptavidin].

For preparation and purification of Streptavidin, two synthetic mediums and a procedure for purifying Streptavidin were studied. We found that Streptomyces avidinii grew vigorously and showed typical colony characterization. At the sametime, these synthetic mediums were in favour of producing Streptavidin with a maximal production of 15.2 micrograms/ml by using DEAE 52 column for purification of Streptavidin. This purification procedure is very simple and easy, and could be widely used.

Bacterial Proteins↗
PubMed1995

[Depression of TTX-blocking effect on Na+ current by 8A5, an anti-TTX monoclonal antibody].

Anti-TTX effect of 8A5 on Na+ current was observed by whole-cell voltage-clamp technique in NG108-15 cells. The results show that 8A5 inhibits TTX action efficiently: (1) When 1 mumol/L TTX is added to the normal perfusion solution INa disappears immediately, and can be restored to the control level with futher addition of 8A5. (2) When the cell is pre-incubated with 1 mumol/L 8A5, 1 mumol/L TTX can only cause a partial inhibition of INa.

Animals↗
PubMed1995

[Angiotensin II increasing the inhibitory effects of electroacupuncture on the nociceptive discharge of neurons in the spinal dorsal horn].

Experiments were performed on 53 rats. The nociceptive discharges of spinal dorsal horn neurons were extracellularly recorded by glass microelectrodes and tested for the effects of angiotensin II (A II) on the nociceptive discharges of spinal dorsal horn neurons and AII on the inhibitory effects of electroacupuncture (EA). The results showed as follows: (a) The nociceptive discharges of spinal dorsal horn neurons might be inhibited (25/35) or facilitated (10) with A II (50-500 ng/20 ul) applied to the surface of dorsal spinal cord (L2-3); (b) The facilitory effects (5/5) were observed with A II (2 ug/20 ul) applied to the surface of dorsal spinal cord; (c) The inhibitory effects of EA (20 Hz, 2-4 V, 5 min) could be increased with A II (250 mg/20 ul, 8/9). Therefore, A II may modulate the nociceptive response of spinal dorsal horn neurons and influence the effects of EA, and different effects can be produced when the different dosage of A II is applied to the surface of dorsal horn.

Angiotensin II↗
PubMed1994

Ntk: a Csk-related protein-tyrosine kinase expressed in brain and T lymphocytes.

The activity of Src-related protein-tyrosine kinases is repressed by the phosphorylation of a conserved carboxyl-terminal tyrosine by another cytoplasmic protein-tyrosine kinase termed p50csk. In this study, we characterize Ntk, a protein-tyrosine kinase bearing striking similarities to p50csk. Like p50csk, Ntk possesses Src homology 3 and Src homology 2 domains and lacks the consensus tyrosine phosphorylation and myristoylation sites found in members of the Src family. Expression of ntk transcripts was maximal in brain, and was observed at significant levels in thymus and spleen. ntk RNA levels were dramatically reduced upon mitogenic stimulation of normal T lymphocytes and were minimal in transformed T-cell populations. Firm evidence that Ntk is a Csk-related enzyme was provided by the observation that it phosphorylated a Src-related polypeptide on the inhibitory carboxyl-terminal tyrosine. These findings indicate that Ntk is a Csk-related enzyme that may play an inhibitory role in the control of T-cell proliferation.

Amino Acid Sequence↗
PubMed1994

Differential changes in relative levels of arachidonic acid in major phospholipids from rat tissues during the progression of diabetes.

Changes in the fatty acid composition of choline glycerophospholipid (CGP) and ethanolamine glycerophospholipid (EGP) in the liver, heart, kidney, testis, spleen, and brain of rats were examined at various stages of streptozotocin-induced diabetes. Diabetes of prolonged duration (8 weeks) caused profound alterations in the fatty acid composition of phospholipids in these tissues, the most consistent of which were a decrease in the relative level of arachidonic acid and an increase in that of linoleic acid. Although a decrease in the relative proportion of arachidonic acid in CGP was a common feature seen in all tissues after long-term diabetes, the profile of the reduction during the progress of diabetes differed among the tissues. A rapid decrease was found in the liver and plasma at an early stage of diabetes (7 days), while the reductions level of arachidonic acid in CGP of the heart, kidney, and testis appeared at a later stage of diabetes (3 weeks). CGP from the brain retained the normal amount of arachidonic acid over the first 4 weeks of diabetes and no consistent changes in the fatty acid composition of phospholipids were found during this time. A slight change in the level of arachidonic acid composition in CGP from the brain was found after 8 weeks of diabetes. The present study indicates that the extent of reduction in the levels of arachidonic acid of CGP in the tissues examined was dependent on the duration of diabetes in every case.

Animals↗