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Biomedical subjects

M Yu

Publications and source records attributed to M Yu.

At least 343 records · Page 19Linked to original sources
PubMed1994

Inhibitory nerve distribution and mediation of NANC relaxation by nitric oxide in horse airways.

The distribution of inhibitory nerves and the mediator of the inhibitory nonadrenergic noncholinergic (iN-ANC) nervous system were investigated in smooth muscle preparations from seven regions of equine airways. In tissues incubated with atropine and precontracted with histamine, electrical field stimulation produced frequency-dependent relaxation, and the magnitude of the relaxation decreased from trachea to central bronchi and was absent in peripheral airways. The degree of relaxation in bronchi was not simply a function of bronchial size or generation. Propranolol inhibited part of the relaxation only in the cranial trachealis. After propranolol, NG-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, eliminated the remaining relaxation in all preparations. This effect was reversed by L-arginine, the NO precursor, but not by D-arginine. Exogenous NO concentration dependently relaxed trachealis. These results indicate that: 1) adrenergic innervation is limited to cranial trachealis, 2) iNANC nerves supply the trachea and central bronchi, and 3) NO mediates iNANC function.

Animals↗
PubMed1994

Progress towards gene therapy for HIV infection.

The retroviral life cycle and genetic plasticity of human immunodeficiency virus 1 (HIV-1) present unprecedented therapeutic challenges. Twelve years into the HIV epidemic, satisfactory treatment remains elusive. Our current understanding of AIDS pathogenesis calls for early intervention with antiviral agents. Although still in its infancy, human gene therapy holds considerable potential for the long-term treatment of genetic disorders, cancer and chronic infectious diseases. Gene therapy for HIV infection is receiving particularly intensive study: approaches that are in development include both immunotherapy (e.g. therapeutic vaccines and adoptive transfer of CD8+ T-cell clones) and direct antiviral therapy (intracellular immunization). The latter strategies include transdominant modifications of HIV proteins, RNA decoys, antisense RNA, ribozymes and modifications of cellular proteins (e.g. intracellular antibodies, soluble CD4). Several of these strategies are now entering clinical trials. While significant conceptual and technical hurdles remain to be overcome before the promise of gene therapy for HIV infection can be fully realized, progress in this field is likely to be rapid and to contribute to the broader applicability of human gene therapy to the treatment of other disorders.

Clinical Protocols↗
PubMed1994

Intracellular immunization of human T cells with a hairpin ribozyme against human immunodeficiency virus type 1.

T-cell lines (Jurkat and Molt-4) were transduced with retroviral vectors containing a hairpin ribozyme that targets a conserved sequence in the 5' transcribed leader sequence of human immunodeficiency virus (HIV) type 1. Stable cell lines were generated which constitutively and persistently expressed the ribozyme gene driven by either the Moloney retroviral long terminal repeat (LTR) or an internal human tRNA(val) promoter. There was no apparent deleterious effect of long-term ribozyme expression on cell proliferation or viability. Cells expressing ribozyme were resistant to challenge from diverse strains of HIV, including an uncloned clinical isolate. No reverse transcriptase activity or virus infectivity was detectable in the culture supernatants of Jurkat cells expressing the ribozyme driven by the tRNA(val) promoter up to 35 days after challenge with HIV-1/HXB2. Expression of the ribozyme also significantly decreased (by approximately 50- to 100-fold) the efficiency of incoming virus to synthesize viral DNA. These and previously reported results indicate that transfer and expression of the ribozyme gene interfere with both early and late events in the HIV replication cycle and confer long-term resistance to HIV-1 infection.

Base Sequence↗
PubMed1994

[IL-1 beta mRNA expression in patients with rheumatoid arthritis].

Using arthroscopy techniques, 6 synovia samples from patients with rheumatic diseases were obtained. Of these, 2 patients had rheumatoid arthritis (RA), 2 had meniscus damage (MD), 1 had osteoarthritis (OA), and 1 had osteochondritis (OC). Using the guanidinium isothiocyanate method, total RNA from synovia was extracted, and 18S and 28S sedimentation bands (rRNA) were separated by electrophoresis. Plasmid containing the 1.3kb cDNA of IL-1 beta were extracted from E. coli by alkaline lysis. Subsequent digestion with XHO1 and then separation on gel isolated the 1.3kb cDNA for use as a probe. The probe was then labeled with 32P-dATP by nicktranslation and hybridized to the synovial RNA extract. The autoradiograph showed that in 4 cases of non-RA, the IL-1 beta cDNA did not hybridize to the synovial mRNA extract. An intense hybridization band was visible for mRNA from one RA case. The clinical and laboratory parameters and X-rays of both knees and wrists of this case were all abnormal, and a rthroscopic findings showed pathological rheumatoid changes of synovium. In addition, this patient did not receive any DMARDs treatment for the RA. The other RA case did not have any hybridization bands. However, this patient did receive DMARDs treatment, and the RA went into remission. The Northern blot result above suggests that IL-1 beta mRNA expression in synovia is negative in non-RA cases and in cases where RA is in remission after DMARDs treatment. In the case with clinically active RA, IL-1 beta is highly expressed, as evidenced by the intense hybridization band.

Adult↗
PubMed1994

[IL-1 and TNF-alpha bioassay and PGE2 immunoassay of supernatant of cultured synovia in patients with rheumatic diseases].

Using arthroscopy technique, synovia were adopted and cultured, and the supernatant was harvested on 1, 4, 7, 14 and 28 days. The bioactivity of supernatant IL-1 were measured in 33 cases (RA 11 cases), TNF-alpha in 30 cases (RA 9 cases); the content of supernatant PGE2 were measured in 44 cases (RA 11 cases). The results showed that IL-1 Growth Index (GI) and TNF-alpha Killing Rate (KR) in RA group are higher than in non-synovitis group (negative control) with statistically significant difference and that the cultured time of the IL-1 highest value is consistent with TNF-alpha. In RA group, the cases treated with disease-modifying anti-rheumatic drugs (DMARDs), especially using the combined therapy, the activity of IL-1 and TNF-alpha decreased. The contents of PGE2 in RA+ synovitis group were higher than osteoarthritis (OA) + nonsynovitis group with statistically significant difference. In conclusion, cytokines such as IL-1 and TNF-alpha have very important status in the pathogenesis of RA. This work provides some clues for new approaches and strategies in the treatment of RA.

Adult↗
PubMed1994

Transjugular intrahepatic portosystemic stent shunts. Preliminary results in 18 patients.

In 18 consecutive patients receiving the transjugular intrahepatic portosystemic stent shunts (TIPSS), 15 were male and 3 female. The patients aged from 34 to 66 years had liver cirrhosis with portal hypertension and esophageal varices. Twelve had recurrent bleedings from raptured gastroesophageal varices. Shunts were established in 16 of the 18 patients and no operative death was noted. Portal vein pressure was reduced from 3.98 +/- 0.24 kPa before shunting to 2.40 +/- 0.16 kPa after shunting. Doppler ultrasound examination revealed that the maximum blood flow velocity in the main portal vein increased from 14.0 +/- 4.5 cm/sec to 48.0 +/- 16.5 cm/sec. The mean follow-up time in the successful cases was 4.5 months (range 2-8 months). The shunt patency was determined with color Doppler ultrasound in 15 patients: occlusion in one and no accites in 4. Varices disappeared in 8 patients and became less evident in 7. No patients had recurrence of varices bleeding or encephalopathy during follow-up. The results suggest that TIPSS is a safe and effective method for portal decompression in the treatment of variceal hemorrhage, and that portal vein puncture is largely dependent on understanding the three-dimensional relationships between hepatic and portal veins. To achieve an adequate portal decompression, we recommend that a stent of 12 mm in diameter be used in severe cases.

Adult↗
PubMed1994

[The experimental study of prevention and treatment of the side-effects of chemotherapy with acupuncture (comparison among the effect of acupuncture at different acupoint)].

After an intraperitoneal injection of cyclophosphamide in rats, there was pathologic changes in hemopoietic, immune and visceral function. Acupuncture respectively at Zusanli, Dazhui and Shenshu points could decrease the above mentioned harms in the rats, the effect of acupuncture on hemopoietic function: Dazhui more than or equal to Zusanli, Zusanli more than Shenshu; the effect of acupuncture on immune function: Zusanli more than Dazhui, Dazhui more than or equal to Shenshu; the effect of acupuncture on the function of the liver and the kidney: Shenshu more than or equal to Zusanli, Zusanli more than Dazhui. The effect of acupuncture at all three points, i.e. Zusanli. Dazhui and Shenshu was more than that at any single point due to their coordination. There was no obvious effect when acupuncture at non-acupoints on tail.

Acupuncture Points↗
PubMed1994

[The effect of interleukin-2, interleukin-4 and tumor necrosis factor on LAK cells activity].

We studied the effect of single or combination of interleukin-2 (IL-2), interleukin-4 (IL-4) and tumor necrosis factor (TNF) on lymphokine-activated killer cells (LAK) activity which killed both of target cells HepG2 and 2 2,1,5 cells induced for seven days. It was shown that LAK activity induced by the combination of triplet of IL-2, IL-4 and TNF was higher than that induced by single or two of IL-2, IL-4 and TNF, and that enhanced LAK activity was associated with the quantity of IL-2 receptor expression and lysosomes of LAK precursors.

Drug Synergism↗
PubMed1993

Allelic variation in the dihydrofolate reductase gene at amino acid position 95 contributes to antifolate resistance in Chinese hamster cells.

The Chinese hamster lung cell line DC-3F contains two polymorphic dihydrofolate reductase (DHFR) alleles that are defined by an Asp-Asn amino acid sequence difference at position 95 in protein. Previously, we reported that the antifolate-resistant subline DC-3F/A3 overexpressed a Leu22-->Phe mutant of the Asp95 (21k) allele and that this was the basis of its resistance to methotrexate (MTX) and methasquin [P. W. Melera, J. P. Davide, C. A. Hession, and K. W. Scotto, Mol. Cell. Biol., 4: 38-48, 1984]. We now show that another independently selected antifolate-resistant subline of DC-3F, DC-3F8/A55, in addition to being severely compromised in its ability to accumulate MTX, overexpresses a Leu22-->Phe mutant form of the Asn95 (20k) allele. Characterization of purified DHFR from these cells showed that the enzyme displayed a 6-fold higher Kd for MTX (3.92 +/- 0.17 pM) than the wild type (0.58 +/- 0.10 pM), thus explaining its lowered sensitivity to drug. Unexpectedly, however, this value was 4-fold lower than that displayed by the DC-3F/A3 enzyme even though both contain the same (Leu22-->Phe) mutation and differ only at position 95. Indeed, we have also shown that the 21k and 20k wild type enzymes, both containing Leu at position 22, in fact differ by 3-fold (1.58 +/- 0.08 and 0.58 +/- 0.10 pM, respectively) in their Kd's for MTX. This demonstrates that the amino acid at position 95 has an effect on the ability of DHFR to bind MTX. On the other hand, these allelic variants are indistinguishable from each other in their catalytic properties and in their respective Kd's for dihydrofolate. Taken together, these characteristics are consistent with the observation that it is the wild type 21k allele which is preferentially overexpressed at a frequency of 3:1 in MTX-resistant Chinese hamster lung sublines derived by long-term selection in MTX. The results of these studies are novel in that they establish a role for allelic variation in the DHFR gene as a contributor to antifolate resistance in mammalian cells. Moreover, they implicate amino acid position 95 in the maintenance of the structure of the MTX binding pocket.

Alleles↗
PubMed1993

Dependence of calmodulin localization in the retina on the NINAC unconventional myosin.

Calmodulin is a highly conserved regulatory protein found in all eukaryotic organisms which mediates a variety of calcium ion-dependent signalling pathways. In the Drosophila retina, calmodulin was concentrated in the photoreceptor cell microvillar structure, the rhabdomere, and was found in lower amounts in the sub-rhabdomeral cytoplasm. This calmodulin localization was dependent on the NINAC (neither inactivation nor afterpotential C) unconventional myosins. Mutant flies lacking the rhabdomere-specific p174 NINAC protein did not concentrate calmodulin in the rhabdomere, whereas flies lacking the sub-rhabdomeral p132 isoform had no detectable cytoplasmic calmodulin. Furthermore, a defect in vision resulted when calmodulin was not concentrated in the rhabdomeres, suggesting a role for calmodulin in the regulation of fly phototransduction. A general function of unconventional myosins may be to control the subcellular distribution of calmodulin.

Animals↗
PubMed1993

A hairpin ribozyme inhibits expression of diverse strains of human immunodeficiency virus type 1.

Ribozymes have enormous potential as antiviral agents. We have previously reported that a hairpin ribozyme expressed under the control of the beta-actin promoter that cleaves human immunodeficiency virus type 1 (HIV-1) RNA in the leader sequence can inhibit HIV-1 (pHXB2gpt) expression. For such a ribozyme in a retroviral vector delivery system to be useful in gene therapy for the treatment of HIV-1 infection, it must be able to inhibit the expression of multiple HIV-1 strains. We have now cloned this ribozyme into various regular expression vectors (including retroviral vectors) by using various gene expression control strategies. Here we show by transient transfection that inhibition of expression of diverse strains of HIV-1 can be achieved by this ribozyme expressed in the proper vectors. These data further support the potential of this hairpin ribozyme as a therapeutic agent for HIV-1.

Antiviral Agents↗
PubMed1993

Selective increase in type II estrogen-binding sites in the dysplastic dorsolateral prostates of noble rats.

We demonstrated previously that simultaneous treatment of intact Noble (NBL) rats with testosterone and estradiol-17 beta (E2) for 16 weeks consistently induced a putative precancerous lesion, termed dysplasia, in the dorsolateral prostate (DLP) of all animals. Since treatment of rats with androgen alone did not elicit the same response, we concluded that estrogen played a critical role in the genesis of this proliferative lesion. In the present study, using radioligand binding assays, we investigated the properties and distributions of nuclear estrogen-binding sites in the two major prostatic lobes (DLP and ventral prostate) of the rat gland and examined the kinetics of alterations in estrogen-binding site levels following treatment of NBL rats with testosterone plus E2. Saturation analyses revealed two distinct types of nuclear [3H]E2-binding sites in the rat prostate. The high-affinity species or type I sites bound [3H]E2 with high affinity (KD 4-5 nM) and low capacity (0.4-0.6 pmol/mg DNA) and had a ligand specificity similar to that described for the classical estrogen receptor. The second estrogen-binding species or type II sites bound [3H]E2 with moderate affinity (KD 25-30 nM) and higher capacity (2-4 pmol/mg DNA) and had characteristics similar to those of type II estrogen-binding sites found in the rat uterus. Type I sites were found in the nuclei of both ventral prostate and DLP, and their levels in the two prostatic lobes did not change following testosterone plus E2 treatment of NBL rats. In contrast, type II sites were present exclusively in the nuclei of DLP. Treatment of NBL rats with testosterone plus E2 for a period of 16 weeks induced a gradual increase in the levels of DLP nuclear type II sites, which was accompanied by parallel increases in DLP wet weight and total DNA content. Since nuclear type II sites have been implicated as a proliferation regulator, our findings suggest that (a) the lobe-specific localization of type II sites in rat DLP may confer unique estrogenic susceptibility on this tissue and (b) elevation of nuclear type II sites in rat DLP following testosterone plus E2 stimulation may be the underlying cause of enhancement of cell proliferation and dysplasia induction in this prostatic lobe.

Animals↗