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Biomedical subjects

H Lu

Publications and source records attributed to H Lu.

At least 433 records · Page 24Linked to original sources
PubMed1993

Immunoglobulin class and subclass distribution of antibodies reactive with the immunodominant antigen of Actinobacillus actinomycetemcomitans serotype b.

The aims of this study were to determine the immunodominant antigens of Actinobacillus actinomycetemcomitans serotype b (Aab) for the different immunoglobulin (Ig) classes and subclasses and to determine the relative levels of these different Igs in serum. Seropositive early-onset periodontitis patients were sampled, and the Ig classes IgG, IgA, and IgM and subclasses IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2 were studied. Reactivity with Aab antigens was assessed by using the Western blot (immunoblot) in limiting dilution analysis and radioimmunoassay with sera from 13 early-onset periodontitis subjects. A smeared antigen in the upper portion of the immunoblots, typical of high-molecular-weight LPS, was immunodominant for IgG, IgA, IgM, IgG1, IgG2, IgG3, IgA1, and IgA2. This smeared antigen was present in every patient for all of these Igs at the endpoint. A few additional antigens were also present at the endpoint in some patients, but none were present in more than half of the subjects. The distribution of antibody titers by Ig classes reactive with the Aab immunodominant antigen was IgG > IgA > IgM. The distribution of antibody titers by IgG subclass was IgG2 > IgG1 approximately IgG3. Further quantitation by radioimmunoassay revealed that the mean concentration of IgG2 (65.7 micrograms/ml) was significantly greater than that of IgG1 (8.8 micrograms/ml). The IgA subclass distribution was IgA1 >> IgA2, with IgA1 apparently being second only to IgG2. Therefore, the Aab antigen eliciting the highest antibody level in virtually all Ig classes and subclasses appeared to be lipopolysaccharide, and IgG2 was markedly elevated over all other serum Ig classes or subclasses reactive with Aab.

Adult↗
PubMed1993

Treatment of secretory pituitary adenoma with radiation therapy.

A retrospective review of 44 patients with secretory pituitary adenoma treated with radiation therapy (median total dose of 4,500 cGy with a median fraction size of 225 cGy) was performed to analyze response rates and possible variables associated with failure to respond and with complications. The treatment technique used for 75% of the patients was a combination field; an opposed-lateral fields technique was used for the remainder. Median follow-up was 78.5 months, with 59% followed up for more than 60 months and 34% for more than 120 months. Overall survival was 90%, and disease-free survival was 62%. Response rates were 86% for the group with prolactinoma, 67% for the group with acromegaly, and 50% for the group with Cushing disease; the overall response rate was 71%. Findings of suprasellar extension and those from treatment with opposed-lateral fields correlated significantly with failure to respond. A higher percentage of patients with invasive macroadenomas also failed to respond. More complications were found in patients treated with opposed-lateral fields, but the numbers were too small to reach significance. Radiation therapy remains an important adjunct for the treatment of many patients with secretory pituitary adenoma.

Acromegaly↗
PubMed1993

Experimental infection of Paragonimus westermani in mice and rats.

To determine the infectivity and maturity of metacercariae of Paragonimus westermani after keeping at low temperature for a long period, 45 mice and 45 rats were each infected with 20 metacercariae which were kept at 4 degrees C for 8 to 234 days. The worm recovery in mice increased with age of worm and reached a peak of 32% at 41-50 days and then decreased with age. The rate in rats first decreased to a lowest point of 6% at 71-100 days and then increased with age. In 42 infected mice and 41 infected rats, 187 immature worms (183 tiny and 4 juvenile ones) and 190 worms (164 tiny, 19 juvenile and 7 mature ones) were recovered respectively. Two worm cysts with eggs only and 8 empty worm cysts were also found in the rats. In addition, the frozen metacercariae can still develop to mature worms in SD rats.

Animals↗
PubMed1993

Update on skeletal muscle ventricles as aortic diastolic counterpulsators.

Skeletal muscle ventricles are constructed from canine latissimus dorsi muscle. These skeletal muscle ventricles can be placed subcutaneously on the chest wall or inside the chest cavity. Skeletal muscle ventricles are connected to the descending thoracic aorta and activated to pump blood as aortic diastolic counterpulsators. The skeletal muscle ventricle in 1 animal pumped blood in the circulation for 27 months. Skeletal muscle ventricles can also function effectively under the condition of low cardiac output. Although thrombus has been detected in some skeletal muscle ventricles, thromboembolism to distal organs has been detected only rarely during the past few years. This research appears promising; however, skeletal muscle ventricle rupture remains a problem and currently accounts for about 30% of the mortality in the long-term experiments. It occurs at the site between the skeletal muscle ventricle outlet and the Dacron sewing ring that is necessary to connect conduits from the skeletal muscle ventricle to the animal's circulation. We believe that skeletal muscle ventricle rupture is likely to be a solvable problem. Once a solution has been found, skeletal muscle ventricles may be ready for clinical use in patients with chronic congestive heart failure.

Animals↗
PubMed1992

Ku autoantigen is the regulatory component of a template-associated protein kinase that phosphorylates RNA polymerase II.

The carboxyl-terminal domain of RNA polymerase II contains a tandemly repeated heptapeptide sequence. Previous work has shown that this sequence is phosphorylated at multiple sites by a template-associated protein kinase, in a reaction that is closely associated with the initiation of RNA synthesis. We have purified this kinase to apparent homogeneity from human (HeLa) cells. The purified kinase phosphorylates native RNA polymerase II only in the presence of DNA and the general transcription factors TFIID (TBP), TFIIB, and TFIIF. Two kinase components are required for full activity: a catalytic component and a DNA-binding regulatory component. The regulatory component has been identified as Ku autoantigen, based on the molecular weights of its component polypeptides, its DNA-binding properties, and its reactivity with anti-Ku monoclonal antibodies. The Ku autoantigen recruits the catalytic component of the kinase to the template. Ku autoantigen has been previously proposed to interact with DNA by a characteristic bind-and-slide mechanism. This mode of interaction may provide a mechanism for targeting the kinase to the transcription complex and other DNA-bound substrates.

Antigens, Nuclear↗
PubMed1992

Human general transcription factor IIH phosphorylates the C-terminal domain of RNA polymerase II.

Phosphorylation of the carboxy-terminal domain of the largest subunit of RNA polymerase II is believed to control the transition from transcription initiation to elongation. The general transcription factor IIH (TFIIH) contains a kinase activity capable of phosphorylating this domain. Factors that promote the association of RNA polymerase II with the preinitiation complex stimulate this activity. The transcription factor IIE, which is required for the stable association of TFIIH with the preinitiation complex, affects the processivity of TFIIH kinase.

Adenosine Triphosphate↗
PubMed1992

Specific interaction between the nonphosphorylated form of RNA polymerase II and the TATA-binding protein.

Fractionation of a transcription-competent HeLa cell extract on a column containing one copy of the heptamer repeat (YSPTSPS) present in the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II resulted in the loss of transcriptional activity. Fractionation of the extracts on columns containing mutations of the heptamer repeat was without effect. Such transcriptionally inactive extracts regained their ability to specifically transcribe different class II promoters upon the addition of human TFIID, recombinant yeast TATA-binding protein (TBP), or proteins bound to the column. Fractionation of RNA polymerase II on columns containing human or yeast TBP resulted in the specific retention of the nonphosphorylated form of RNA polymerase II. The phosphorylated form of the enzyme was unable to interact with TBP. The specific interaction of RNA polymerase II with TBP was mediated by the CTD of RNA polymerase II.

Amino Acid Sequence↗
PubMed1992

Factors involved in specific transcription by mammalian RNA polymerase II. Identification and characterization of factor IIH.

Two new factors required for transcription of class II genes have been identified. These factors, TFIIH and TFIIJ, were required together with the previously described general factors (TFIIA, TFIIB, TFIID, TFIIE, and TFIIF) and RNA polymerase II for transcription of different class II genes. TFIIH was extensively purified, and the activity appeared to coelute with polypeptides of 33 and 95 kDa. The role of TFIIH and TFIIJ in preinitiation complex assembly was analyzed using mobility shift assays. It was found that TFIIH and TFIIJ association with the preinitiation complex was ordered and required the previous assembly of a preinitiation complex intermediate containing factors IID, IIB, IIF, IIE, and RNA polymerase II. A model for the ordered assembly of the general factors and RNA polymerase II is presented.

Blotting, Western↗
PubMed1992

Skeletal muscle ventricles with improved thromboresistance: 28 weeks in circulation.

Skeletal muscle ventricles (SMVs) were constructed from the left latissimus dorsi in 22 mongrel dogs. The configuration of these SMVs was different from those previously reported. The animals were divided into two groups: group A (n = 11) SMVs rested for 10 weeks after construction; group B (n = 11) SMVs rested for 18 weeks. At the end of the delay period, SMVs were tested in vivo with a mock circulation device. The SMVs in group B developed stroke work greater than those in group A. After acute testing, SMVs (n = 12) were connected to the descending thoracic aorta and stimulated to contract during diastole. Aortic diastolic counterpulsation was achieved in all dogs, with 9 animals surviving from 1 to beyond 28 weeks. In all of the dogs surviving 1 week or more, the SMVs remained free of thrombus. Aspirin was used as the only antithrombotic agent. Skeletal muscle ventricles in this study were able to develop stroke work similar to that previously reported, intermediate between that of the right and left ventricular stroke work, with a significantly decreased incidence of thromboembolism.

Animals↗
PubMed1992

Skeletal muscle ventricles as left atrial-aortic pumps: short-term studies.

In 5 dogs, skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle and placed in the left hemithorax. After a 3-week vascular delay period, SMVs were electrically preconditioned with 2-Hz stimulation for 6 weeks. At a second operation, SMVs were connected between the left atrium and thoracic aorta by afferent and efferent aortic root homografts, and stimulated to contract in a 1:2 diastolic mode. At a mean left atrial pressure of 12.4 +/- 1.3 mm Hg and a burst stimulation frequency of 33 Hz, SMV stroke volume was initially 43% of that of the native left ventricle, achieving a flow equivalent to 21% of cardiac output (194 +/- 38 versus 902 +/- 85 mL/min). At 50-Hz stimulation, this figure rose to 27% (246 +/- 41 mL/min; p less than 0.05). Skeletal muscle ventricle power output (the product of stroke work and contraction rate) at 33 Hz was 0.016 +/- 0.003 W, increasing to 0.024 +/- 0.004 W at 50 Hz (p less than 0.05), corresponding to 14% and 22%, respectively, of left ventricular power output (0.11 +/- 0.012 W). After 4 hours of continuous pumping, four of the SMVs were still generating flows of more than 70% of starting values and more than 60% of initial power output. This study demonstrates that SMVs can function in the systemic circulation at physiologic left atrial preloads.

Animals↗
PubMed1992

Skeletal muscle ventricles in the pulmonary circulation: up to 16 weeks' experience.

Skeletal muscle ventricles (SMVs) were constructed from the right latissimus dorsi muscle of 8 mongrel dogs. After a 3-week vascular delay period, each SMV was electrically preconditioned with 2-Hz continuous stimulation of the thoracodorsal nerve for 6 weeks. A porcine-valved conduit was then anastomosed between the right ventricle and the SMV, with a second valved conduit connecting the SMV to the main pulmonary artery. The pulmonary artery was then ligated proximal to the conduit. The SMVs were stimulated to contract in 1:2 diastolic mode with a 33-Hz burst frequency. Effective right ventricular assist was achieved in all dogs. Cardiac output increased by 22.6% (1,799 +/- 97 versus 1,467 +/- 84 mL/min; p less than 0.001), systemic systolic arterial pressure by 9.3% (90.1 +/- 3.5 versus 82.4 +/- 3.9 mm Hg; p less than 0.005), and peak pulmonary artery pressure by 31.8% (27.8 +/- 2.0 versus 21.1 +/- 1.7 mm Hg; p less than 0.001) at the initiation of this study. In 6 dogs, effective right heart assist was sustained for periods of between 1 week and 12 weeks. Two dogs survived for longer than 3 months, though with evidence of deteriorating SMV function. These results demonstrate the feasibility of providing sustained right ventricular assist using this modified "Rastelli-SMV" configuration, which obviates the limitations imposed by low right atrial preload.

Adaptation, Physiological↗
PubMed1992

Anti-oxidant activity of dibenzocyclooctene lignans isolated from Schisandraceae.

The anti-oxidant activity of nine dibenzocyclooctene lignans isolated from Schisandra chinensis, S. rubriflora, and Kadsura longipedunculata, respectively, was studied. Seven of the 9 lignans (1 mM) inhibited iron/cysteine-induced lipid peroxidation (malondialdehyde, MDA, formation) of rat liver microsomes as well as superoxide anion production in the xanthine/xanthine oxidase system. The actions of the 7 lignans were much more potent than vitamin E at the same concentration of 1 mM. Among the lignans, schisanhenol was the most active one. This compound also prevented the decrease of membrane fluidity of liver microsomes induced by iron/cysteine. The results indicated that seven of the lignans such as schisanhenol have anti-oxidant activities.

Animals↗
PubMed1992

Surfactant protein C: hormonal control of SP-C mRNA levels in vitro.

We have studied hormonal regulation of the surfactant protein C (SP-C) in fetal 18-dah rat lung explants. SP-C mRNA was detected in Northern blots with a specific rat SP-C cDNA probe and quantified by densitometry. Treatment of the explants with dexamethasone resulted in a dose-dependent increase of the SP-C mRNA level. Transcriptional assays have shown that the regulation of SP-C mRNA by dexamethasone involves a transcriptional step. Administration of the cAMP analogues, 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), produced a dose-dependent increase of SP-C mRNA levels, with maximum stimulation observed at 200 microM. The thyroid hormone T3 had no effect on SP-C mRNA levels, whether administered alone or in combination with dexamethasone. Variation in the effects of the above hormones on three surfactant protein mRNAs, SP-A, SP-B and SP-C, indicates that the hormonal regulation of the surfactant proteins is a complex process and that each gene is, in part, differentially regulated.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Identification of Leishmania donovani isolates from different kala-azar foci in China by kDNA hybridization.

kDNA sequence homology of Leishmania donovani isolates from three types of kala-azar foci in China were analyzed by using dot and Southern hybridization with biotin- and 32P-labelled probes. The results revealed kDNA sequence heterogeneity among Leishmania donovani isolates from the three kala-azar foci: sequence homology between isolates of hill and desert foci was higher than that between hill and plain foci isolates. The kDNA hybridization technique was also found to be specific and sensitive for direct identification of Leishmania in animal tissues. In a preliminary survey, kDNA hybridization of cutaneous tissue blots of 71 dogs from endemic regions showed a positive rate of 40.8%, and the rate of double positive cases (touch blot hybridization and bone marrow smear) reached 91.3%. The direct identification of Leishmania in tissues by kDNA hybridization seems to be a useful and convenient method for epidemiological study and clinical diagnosis, especially for species/strain characterization.

Animals↗
PubMed1991

Hemostasis in patients undergoing extracorporeal circulation: the effect of aprotinin (Trasylol).

The administration of aprotinin during extracorporeal circulation (ECC) reduces blood loss. To explore the mechanism of this effect, a placebo-controlled double-blind study was performed in 20 patients (10 were administered with a high dose of aprotinin, 10 with placebo) undergoing a primary, elective operation of coronary artery bypass grafting (CABG) with ECC. Biological tests were performed at 4 different time points during the operation. A marked reduction in the placebo group of ristocetin-induced platelet agglutination (binding of von Willebrand factor [vWF] to platelet glycoprotein [GP] Ib) was shown during ECC and at the end of surgery, but not in the aprotinin group. This abnormality is not related to the hydrolysis of vWF or GP Ib, since washed platelets were resuspended in pooled normal plasma which provided a constant amount of vWF in this test and since the plasma concentration of the fragment of GP Ib (glycocalicin) did not correlate with this abnormality. Despite a high concentration of heparin (5-7 IU/ml) in patient's plasma during bypass, activation of blood coagulation in both groups was evidenced by an increase in ATm (thrombin-modified antithrombin III) level. The level of ATm in the placebo group reached a maximum at the end of ECC during rewarming, while in the aprotinin group, ATm level at this time point was significantly lower than in the control group. In comparison to the placebo group, the generation of the fibrin degradation products (DDE complexes) was inhibited by aprotinin during ECC, but the level of DDE complexes in the aprotinin group was slightly elevated after ECC, although much less than in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1991

The small subunit of transcription factor IIF recruits RNA polymerase II into the preinitiation complex.

We found that transcription factor IIF mediates the association of RNA polymerase II with promoter sequences containing transcription factors IID, IIB, and IIA (DAB complex). The resulting DNA-protein complex contained RNA polymerase II and the two subunits of transcription factor IIF (RAP 30 and RAP 74). Cloned human RAP 30 was sufficient for the recruitment of RNA polymerase II to the DAB complex. This ability of RAP 30 to recruit RNA polymerase to a promoter is also a characteristic of sigma factors in prokaryotes.

Adenoviridae↗