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Biomedical subjects

Q Lin

Publications and source records attributed to Q Lin.

At least 199 records · Page 11Linked to original sources
PubMed1996

Involvement of alpha-2 adrenoceptors in the periaqueductal gray-induced inhibition of dorsal horn cell activity in rats.

The noradrenergic system is considered to be one of the major descending analgesia systems originating in the brainstem. The relationship between the periaqueductal gray (PAG) and the descending noradrenergic system is of great interest. A projection from the PAG to the locus ceruleus and parabrachial region has been reported. It is possible that electrical stimulation of the PAG activates spinally projecting collaterals of the noradrenergic cells in A5, the locus ceruleus, subceruleus and A7/Kölliker-Fuse nucleus. The current experiments were designed to study the role of alpha-2 adrenoceptors on spinal cord dorsal Horn cells in PAG-induced inhibition. A microdialysis fiber was introduced into the dorsal horn of the lumbar enlargement for drug administration. An electrode was placed in the vicinity of the microdialysis fiber for extracellular single-unit recording. Recordings were made from a total of 35 cells from 22 Sprague-Dawley rats (270-360 g). When the PAG was stimulated, responses to mechanical stimuli applied to the skin (brush, press and pinch) were inhibited. When an alpha-2 adrenoceptor agonist (clonidine) was administered, the background activity and the responses of the cell to brush, press and pinch stimuli were decreased. In contrast, administration of alpha-2 adrenoceptor antagonists (idazoxan or yohimbine) increased the responses of the cell to brush, press and pinch stimuli. The background activity was also increased by idazoxan. The PAG-induced inhibition of the response to mechanical stimuli was reduced by idazoxan and yohimbine. These results suggest an involvement of alpha-2 adrenoceptors in the mechanism of PAG-induced inhibition of dorsal horn cell activity.

Animals↗
PubMed1996

Antinociception and inhibition from the periaqueductal gray are mediated in part by spinal 5-hydroxytryptamine(1A) receptors.

Although 5-hydroxytryptamine (5-HT) is known to be involved in the mediation of antinociception from the periaqueductal gray (PAG), its mode of action remains obscure. This investigation uses selective 5-HT(1A) receptor agonist and antagonist drugs in both behavioral and electrophysiological studies on antinociceptive mechanisms of the PAG of rats. Intraspinal administration of 8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT), a selective 5-HT(1A) agonist, by microdialysis produced a dose-dependent antinociception in the radiant-heat paw withdrawal test. Dorsal horn neuronal activity was recorded extracellularly to test responses to noxious cutaneous stimuli when 8-OH-DPAT was administered iontophoretically, and it was observed that the noxious-evoked responses were inhibited in a current-related manner in all cells examined. The inhibitory effects elicited by 8-OH-DPAT could be selectively blocked by perfusion of the spinal cord with S-(--)-propranolol, a selective 5-HT(1A) antagonist. The antinociception produced by microinjection of morphine into the PAG was significantly attenuated in a dose-related manner by S-(--)-propranolol administered into the spinal cord. Similarly, the inhibition of dorsal horn neuronal responses to cutaneous mechanical stimuli produced by electrical stimulation in the PAG was reduced by S-(--)-propranolol administered into the spinal cord in the majority of cells tested. These data suggest that the release of 5-HT in the dorsal horn by stimulation in the PAG may act directly on spinal 5-HT(1A) receptors, resulting in inhibition of dorsal horn neurons. This is presumably one of the antinociceptive mechanisms of the descending serotonergic inhibitory pathway.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1996

[Immunotherapy of primary habitual abortion].

OBJECTIVE: To investigate whether different number of times of immunization and different immunogens have any effect on the outcome of pregnancy in patients with history of primary habitual abortion. METHODS: 38 cases of pregnant women with history of primary habitual abortion immunized with lymphocytes were analysed retrospectively. RESULTS: The results showed that the successful pregnancy rate was 87.5% (14/16) in the women immunized two times and was 86.4% (19/22) in the women immunized four times. There was no significant difference between the two groups. The successful pregnancy rate was 84.2% (16/19) in women immunized with their husbands' lymphocytes and 89.5% (17/19) in women immunized with donors' lymphocytes. There was also no significant difference between the two groups. CONCLUSIONS: In order to prevent hematogenous infection, active immunization could be reduced from four to two times and the immunogens may be selected from the husband or from healthy donor.

Abortion, Habitual↗
PubMed1996

[Limb-preserving segmental bone resection for malignant bone tumors of the extremities: a report of 27 cases].

Segmental bone resection with preservation of the affected limb was performed in 27 patients with malignant bone tumors. Diagnosis as confirmed by histopathology was: osteosarcoma (n = 8), chondrosarcoma (n = 3), fibrosarcoma (n = 2), malignant fibrous histiocytoma (n = 2), giant cell tumor (n = 6), reticulum cell sarcoma (n = 1), myeloma (n = 1) and metastatic bone tumor (n = 4). Four different kinds of operative procedure were used: enbloc resection of shoulder girdle in 13 cases, segmental resection and replantation of distal forearm in 1, partial hemipelvisection in 6 and segmental resection of the lower thigh with leg rotation plasty in 7. Twenty four patients were followed up from 16 months to more then 12 years. Twenty patients survived for more than 2 years, 9 patients survived over 5 years with functional limbs. The 2- and 5-year survival rate was 83.3% and 37.5%, respectively.

Adolescent↗
PubMed1996

[Experimental study on uptake of fluoride by dentin after pulsed Nd:YAG laser irradiation].

The purpose of this study was to determine the uptake of fluoride by dentin after pulsed Nd:YAG laser irradiation. Under SEM examination dentin lased by pulsed Nd:YAG laser appeared to be melted; there were no changes of calcium and phosphorus levels. Dentin irradiated by pulsed Nd:YAG laser and treated with 38% Ag(NH3)2F showed greater uptake and deep penetration of fluoride than topical application of fluoride alone, SEM examination revealed that CaF2-like and Ag3PO4-like deposits were formed on the dentin surface. These results suggested that pulsed Nd:YAG laser irradition could improve the absorption of fluoride in dentin.

Dentin↗
PubMed1996

Interaction of synthetic peptide corresponding to signal sequence of glucitol permease of Escherichia coli and its analogue with liposomes.

The N-terminal signal sequence of glucitol permease of Escherichia Coli (Gut22) and its analogue (Gut22Ana) were synthesized. The analogue had a Pro residue substituting for the His at the 7th position of Gut22 and a Val residue substituting for the Glu at the 10th position. The intrinsic fluorescence emission spectra indicated that the binding of Gut22 with lipid bilayer was much stronger than that of Gut22Ana. The leakage experiments with calcein-loaded liposomes showed that Gut22 strongly perturbed lipid bilayers while Gut22Ana did not. The apparent partition constant of Gut22 for partitioning into phosphatidylserine/phosphatidylcholine bilayers was measured; the effect of membrane potential on the interaction of Gut22 with lipid bilayers was studied and the conformation changes of Gut22 and Gut22Ana upon interacting with liposomes were studied by the method of circular dichroism analysis.

Amino Acid Sequence↗
PubMed1995

Astrocytes retrovirally transduced with BDNF elicit behavioral improvement in a rat model of Parkinson's disease.

Neurotrophic factors that improve the survival of specific neuronal types during development and after exposure to various neuronal insults hold potential for treatment of neurodegenerative diseases. In particular, brain-derived neurotrophic factor (BDNF) has been shown to exert trophic and protective effects on dopaminergic neurons, the cell type known to degenerate in Parkinson's disease. To determine whether increased levels of biologically produced BDNF affect the function or regeneration of damaged dopaminergic neurons, the effects of grafting astrocytes transduced with the human BDNF gene into the striatum of the partially lesioned hemiparkinsonian rat were examined. Replication deficient retroviruses carrying either human prepro-BDNF or human alkaline phosphatase (AP) cDNA were used to transduce primary type 1 astrocytes purified from neonatal rat cortex. In vitro, BDNF mRNA was expressed by BDNF transduced astrocytes (BDNF astrocytes), but not control AP transduced astrocytes (AP astrocytes), as determined by reverse transcription polymerase chain reaction (RT-PCR). The modified astrocytes were injected into the right striatum 15 days after partial lesioning of the right substantia nigra with 6-hydroxydopamine. Transplantation of BDNF astrocytes, but not AP astrocytes, significantly attenuated amphetamine-induced rotation by 45% 32 days after grafting. Apomorphine-induced rotation increased over time in both groups, but was not significantly different in the BDNF-treated group. The modified BDNF astrocytes survived well with non-invasive growth in the brain for up to 42 days. Although BDNF mRNA positive cells were not detected within the graft site using in situ hybridization, alkaline phosphatase immunoreactive (IR) cells were present in control graft sites suggesting that the retroviral construct continued to be expressed at 42 days. Analysis of the density of tyrosine hydroxylase (TH)-IR fibers showed no effect of BDNF on TH-IR fiber density in the striatum on the lesioned side. These findings suggest that ex vivo gene therapy with BDNF ameliorates parkinsonian symptoms through a mechanism(s) other than one involving an effect of BDNF on regeneration or sprouting from dopaminergic neurons.

Amphetamine↗
PubMed1995

Resident bone marrow macrophages produce type 1 interferons that can selectively inhibit interleukin-7-driven growth of B lineage cells.

Type 1 interferons alpha and beta are found to be potent inhibitors of IL-7-induced growth of early B lineage cells, while having no effect on cell growth induced by IL-2, IL-3, IL-4, or autogenous factors. The combination of IL-7 and interferons alpha/beta induces bcl-2 down-regulation and cell death by apoptosis. These conclusions were derived initially from experiments employing exogenous cytokines, but functional type 1 interferons are also shown to be produced by resident bone marrow macrophages. As physiological modulators of IL-7-driven proliferation and cell survival, interferons alpha/beta may cooperate with other homeostatic factors to maintain the balanced production of normal B lineage cells.

Animals↗
PubMed1995

[Clinical and experimental study on codonopsis pilosula oral liquor in treating coronary heart disease with blood stasis].

The effects of Codonopsis pilosula oral liquor (CPOL) on tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) in the plasma of 25 patients of coronary heart disease with blood stasis were studied. It has been shown that those patients had a significant decrease in t-PA activity (P < 0.01) compared to healthy subjects. After 4 weeks of CPOL therapy, platelet aggregation significantly decreased (P < 0.05), there was no significant difference in t-PA and PAI. From the results shown above, it suggested that one of the effects of CPOL in influencing blood coagulation was its inhibition on platelet aggregation, but not through the elevating of fibrinolytic activity.

Adult↗
PubMed1995

[Cryosurgery of acute hemorrhagic necrotizing pancreatitis].

Acute hemorrhagic necrotizing pancreatitis (AHNP) was induced by introduct retrograde injection of the autologous bile in canine. The cryoprobe was under the influence of temperature ranging from -160C to -190C for fifteen to eighteen seconds, and the frozen areas were about 80% surface of pancreas. Cryotherapy of AHNP strongly inhibited the development of the inflammation in pancreatic parenchyma. Postcryotherapy 24hr for remarkably decreased the activities of pancreatic enzymes. The activities of phospholipase A, lipase and amylase in serum decreased by 502.1%, 355.8%, 502.5% respectively in 7 days. The level of blood glucose decreased. At the second week, the fibroblasts were growing around the residual pancreatic aciner cells and insular cells rich in intact zymogen granules. The mortality (6.89%) of the treatment group within 48 hours was significantly lower than that of the control group (100%).

Acute Disease↗
PubMed1995

Clinical application of monoclonal antibody-drug conjugate to immunotargeting chemotherapy of bladder cancer.

Monoclonal antibody-drug conjugate was applied in a clinical trial for patients with bladder cancer. Monoclonal antibody HB7A from a mouse splenocyte immunized against human bladder cancer was used as a drug carrier. The anti-cancer drug adriamycin (ADR) was bound to HB7A through a dextran (DEX) bridge to form the conjugate HB7A-DEX-ADR. The in vitro cytotoxic effect of the conjugate on BIU-87 bladder cancer cells was similar to that of free ADR and the mixture of HB7A and ADR. Seven patients with bladder cancer were given HB7A-DEX-ADR intravenously. The immunoperoxidase studies of the resected specimens showed that HB7A was localized specifically in cancer, and histological studies revealed degenerative and necrotic changes of the tumor cells. Patients receiving the conjugate did not experience serious side effects. This study suggests that immunotargeting chemotherapy with HB7A-DEX-ADR is well tolerated by patients and its cytotoxicity on tumor is substantial.

Aged↗
PubMed1995

[Clinical evaluation of force-sensitive probe in the examination of tooth sensitivity].

Two methods were tested for measuring the sensitivity of dentin to mechanical (force-sensitive probe) and cold air stimuli. Of the 212 sensitive teeth in 71 patients, 94.8% were sensitive to probe, with a mean threshold of 22.79g; 89.6% were sensitive to cold air. These two methods were significantly correlated (P < 0.001). The occlusal sites were less sensitive than the buccal sites measured by probe and cold air. It suggests that force-sensitive probe is a simple, quantitative method of measuring tooth hypersensitivity.

Adult↗
PubMed1994

Archaic structure of the gene encoding transcription factor USF.

The upstream stimulatory factor (USF) is a helix-loop-helix transcription factor that interacts with specific sites on the DNA that are also recognized by the MYC oncoproteins. We isolated genomic clones to the murine 44-kDa form of USF (USF2 gene). This unique gene spans 13 kilobases of DNA and is composed of 10 exons. The gene seems to have maintained its archaic structure, since many of the exons encode discrete functional domains of the transcription factor originally identified by protein sequence comparisons. A particularly striking HpaII tiny fragment island, extending over nearly 2,000 base pairs, surrounds the USF2 translation initiation site. This region, which includes the USF2 promoter and the first four exons, is characterized by an overall GC content greater than 74%. Analysis by S1 mapping and transient transfection assays revealed that the USF2 transcripts originate from an initiator element located within a highly GC-rich region that is surrounded by two long polyadenylate stretches and functions as a bidirectional promoter. Different forms of USF2 messages result from the presence or absence of the fourth exon in the processed USF2 mRNA. Alternative splicing correlates with the lack of a consensus lariat branch point in the third intron. Transient cotransfection assays revealed that the presence or absence of the amino acid sequences encoded by exon 4 affects considerably the transcription activation properties of the USF2 protein.

Alternative Splicing↗
PubMed1994

Glycine and GABAA antagonists reduce the inhibition of primate spinothalamic tract neurons produced by stimulation in periaqueductal gray.

Amino acids are demonstrated to be important neurotransmitters mediating the inhibitory transmission from nucleus raphe magnus to spinal nociceptive dorsal horn neurons. In this study, the role of glycine and GABA in the inhibitory processes evoked by stimulation in periaqueductal gray (PAG) of responses of primate spinothalamic tract (STT) neurons to cutaneous mechanical and thermal stimuli was investigated by examining the effects of strychnine and bicuculline, antagonists of glycine and GABAA receptors, respectively, introduced into the dorsal horn through a microdialysis fiber. The inhibitory effects of iontophoretic application of glycine and GABAA agonists on STT cell activity evoked by noxious mechanical stimulation of the skin were selectively blocked by their specific antagonist, strychnine or bicuculline, infused into the dorsal horn. Similarly, intra-spinal application of strychnine or bicuculline resulted in a significant reduction in the PAG stimulation-induced inhibition of responses of STT cells to cutaneous stimuli. This reduction was mainly on the PAG-induced inhibition of the responses to noxious mechanical stimuli. Our results suggest that glycinergic and GABAergic inhibitory interneurons in the spinal cord dorsal horn synapsing on STT cells are activated during stimulation in PAG and contribute to descending antinociceptive actions.

Animals↗
PubMed1994

Isolation and characterization of cDNA clones for chloroplast translational initiation factor-3 from Euglena gracilis.

A complete cDNA clone encoding Euglena gracilis chloroplast translational initiation factor 3 (IF-3chl) has been obtained. Analysis of the sequence indicates that the IF-3chl mRNA contains the spliced leader found at the 5' end of nuclear encoded mRNAs in E. gracilis. The open reading frame for IF-3chl encodes a 537-amino acid protein. IF-3chl appears to be divided into four domains. The first 140 amino acids correspond to a transit peptide required for the import of IF-3chl into the chloroplast. The mature form of IF-3chl encompasses domains 2-4 and is about twice the size of Escherichia coli IF-3. The second domain has no homology to other known proteins. It begins with a stretch of 35 residues, of which about 30% are proline. Downstream from this region is a stretch of about 25 amino acids with a repeating (GX)n motif followed by a very acidic region. The third domain comprises a region of about 175 residues and has between 31 and 37% homology to the IF-3s found in other organisms. The IF-3 homology domain is followed by an acidic region which has no detectable homology to other sequences. Analysis of E. gracilis genomic DNA suggests that there are about four copies of the IF-3chl gene, one of which is probably a pseudogene. The activity of IF-3chl is inducible by light. However, the IF-3chl mRNA is present in approximately equal amounts in both dark- and light-grown cells, suggesting that the light-dependent induction of IF-3chl activity is post-transcriptional.

Amino Acid Sequence↗
PubMed1994

Ubiquitous expression of the 43- and 44-kDa forms of transcription factor USF in mammalian cells.

USF is a helix-loop-helix transcription factor that, like Myc, recognizes the DNA binding motif CACGTG. Two different forms of USF, characterized by apparent molecular weights of 43,000 and 44,000, were originally identified in HeLa cells by biochemical analysis. Clones for the 43-kDa USF were first characterized, but only partial clones for the human 44-kDa USF (USF2, or FIP) have been reported. Here we describe a complete cDNA for the 44-kDa USF from murine cells. Analysis of this clone has revealed that the various USF family members are quite divergent in their N-terminal amino acid sequences, while a high degree of conservation characterizes their dimerization and DNA-binding domains. Interestingly, the 3' noncoding region of the 44-kDa USF cDNAs displayed an unusual degree of conservation between human and mouse. In vitro transcription/translation experiments indicated a possible role for this region in translation regulation. Alternative splicing forms of the 44-kDa USF messages exist in both mouse and human. Examination of the tissue and cell-type distribution of USF by Northern blot and gel retardation assays revealed that while expression of both the 43- and 44-kDa USF species is ubiquitous, different ratios of USF homo- and heterodimers are found in different cells.

Alternative Splicing↗
PubMed1994

Synthetic images by subspace transforms. I. Principal components images and related filters.

The principal component (PC) approach offers compressions of an image sequence into fewer images and noise suppressing filters. Multiple MR images of the same tomographic slice obtained with different acquisition parameters (i.e., with different TR, TE, and flip angles), time sequences of images in nuclear medicine, and cardiac ultrasound image sequences are examples of such input image sets. In this paper noise relationships of original and linearly transformed image sequences in general, and specifically of original, PC, and PC-filtered images are discussed. As the spinoff, it introduces locally weighted PC transforms and filters, nonlinear PC's, and a single-image based filter for suppression of noise. Examples illustrate increased perceptibility of anatomical/functional structures in PC images and PC-filtered images, including extraction of physiological functional information by PC loading curves. Generally, the more correlated the original images are, the more effective is the PC approach.

Diagnostic Imaging↗