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Biomedical subjects

P Liang

Publications and source records attributed to P Liang.

At least 73 records · Page 4Linked to original sources
PubMed1997

Increased prevalence of mitochondrial DNA deletions in skeletal muscle of older individuals with impaired glucose tolerance: possible marker of glycemic stress.

To determine the relationship between mitochondrial DNA (mtDNA) mutations and age-related impaired glucose tolerance (IGT), mtDNA from skeletal muscle of 19 volunteers, ages 55-75 years, with either IGT or diabetes and 17 age- and sex-matched control subjects was analyzed using a long-extension polymerase chain reaction (PCR) combined with a quantitative PCR. We found the common 4,977-bp deletion in 84% of the IGT/diabetes group compared with only 41% in the control group (P < 0.02). Multiple other deletions of different sizes were identified in 13 out of 19 IGT/diabetes patients (68%) compared with 2 out of 17 control subjects (12%) (P < 0.002). Because of the heterogeneity and variation in the mutations identified, we propose that these mtDNA mutations were the result rather than the cause of IGT. The increase in type and frequency of mtDNA deletions in diabetes and IGT patients may be related to oxidative damage by oxygen free radicals. These may be produced in greater amounts as a result of hyperglycemia or may be more abundant because of an abnormality in the scavenging of free radicals by antioxidants.

Aged↗
PubMed1997

[Pathogenesis and combined treatment of sterility in men with varicocele].

To investigate the pathogenesis of sterility in men with varicocele and summarize the effects of combined treatment, we anallyed ultrastructure of testicular specimens in 21 cases. With combined surgical and medicinal treatment, 16 men (76.2%) made their wives pregnant during a period of 2 years after the operation. Electron microscopy disclosed glycogen infiltration of sertoli cells, and decreased spermatogenesis especially involving the middle and late stages. Defective carbohydrate and energy metabolism in the testis is suggested as the key point in the pathogenesis of sterility, and a combined surgical and medicinal treatment is beneficial to the increase of pregnant rate.

Adult↗
PubMed1997

[Clinical application of ultrasound(US)-guided percutaneous microwave coagulation therapy for liver cancer].

OBJECTIVE: To evaluate clinical application of US-guided percutaneous microwave coagulation therapy for liver cancer. METHODS: 32 patients with 57 nodules of liver cancer were treated, 57 nodules were coagulated by 92 times at 182 different points. Output of one coagulation was 60 W last mg 240-300 sec. RESULTS: The follow-up period was 5-18 months, averaging 10.4 months. 29 patients remained alive, 3 patients died. After treatment, 85.9%(49/57) of the nodules decreased in size; color blood flow signal disappeared in 78.2(36/46) nodules on color and energy Doppler scans; and there was no enhancement in 76.4%(25/34) tumors on enhanced CT scans. In 13 patients with increased AFP level before therapy, it dropped to normal after treatment in 11 patients. Of 27 patients whoes a good general condition was good, 19 patients gained bodies weight. Repeated biopsy in 14 cases showed complete tumor necrosis with fibrosis in 12. CONCLUSION: US-guided percutaneous microwave coagulation therapy is able to induce total tumor necrosis of liver cancer in most cases. It can be expected as an important non-operative therapy of liver cancer.

Adult↗
PubMed1997

Role of alternative splicing of the rat erythropoietin receptor gene in normal and erythroleukemia cells.

An alternatively splicing of the rat erythropoietin receptor (EpoR) gene was identified in normal and erythroleukemia cells by the reverse transcription PCR method. Insertion of a 105 bp fragment at the region corresponding to the extracellular domain of rat EpoR was found. The insert sequence, which encodes additional 21 amino acids, is similar to that previously found in the mouse EpoR gene, however, has an additional 27 bp direct repeat. Due to the presence of a stop codon in the insert, the alternative transcript is translated to a truncated and soluble form of EpoR which is preferentially expressed in liver, spleen, kidney, heart, and bone marrow cells as well as cultured erythroleukemia cells. These findings suggest that alternative splicing of the EpoR gene may play an important role in proliferation and differentiation of rat erythroid cells.

Alternative Splicing↗
PubMed1996

Two differentially expressed genes in normal human prostate tissue and in carcinoma.

Alterations in transcriptional control may contribute directly to carcinogenesis. Using the differential display technique in prostate cancer cells compared to normal prostate epithelial cells, we identified a down-regulated gene and an up-regulated gene in cancer cells. The down-regulated gene encodes human epithelial tropomyosin (TMe1), a member of the family of actin filament-binding proteins. The up-regulated gene encodes cytochrome c oxidase subunit VIc (COSVIc), a protein of the respiration chain in the mitochondrial inner membrane. The differential display pattern was confirmed by Northern hybridization in both prostate tissue and cell lines. In situ hybridization of malignant prostate epithelial tissue using a digoxigenin-labeled antisense riboprobe detected strong staining for mRNA of COSVIc, as opposed to very weak staining in normal prostate epithelium. The expression pattern of COSVIc may be a useful marker for studying the alteration of energy metabolism in cancer cells and for the diagnosis of prostate cancer.

Base Sequence↗
PubMed1996

Electrochemiluminescence-based detection of beta-lactam antibiotics and beta-lactamases.

Bacterial resistance to clinically administered beta-lactam antibiotics is usually caused by beta-lactamases, enzymes that hydrolytically inactivate the antibiotics. This paper describes the use of electrogenerated chemiluminescence (ECL) to detect beta-lactam antibiotics and their hydrolysis by beta-lactamases. All 10 tested antibiotics were detected on the basis of their ability to participate in an ECL reaction with ruthenium(II) tris(bipyridine). In every case, antibiotic-promoted ECL changed when the antibiotic was hydrolyzed by beta-lactamases or NaOH. Standard curves of antibiotic concentration versus ECL intensity showed that antibiotics could be quantitated to low micromolar concentrations. Substrate profiles were generated for four beta-lactamases using six structurally diverse beta-lactam antibiotics. ECL-based antibiotic detection was accomplished in untreated whole milk, and beta-lactamases were detected in crude bacterial broth culture. Because several structurally diverse antibiotics were detectable by ECL, this method may become valuable for the detection of many or all beta-lactam antibiotics and their inactivation by beta-lactamases.

Anti-Bacterial Agents↗
PubMed1996

AdipoQ is a novel adipose-specific gene dysregulated in obesity.

Adipose differentiation is accompanied by changes in cellular morphology, a dramatic accumulation of intracellular lipid and activation of a specific program of gene expression. Using an mRNA differential display technique, we have isolated a novel adipose cDNA, termed adipoQ. The adipoQ cDNA encodes a polypeptide of 247 amino acids with a secretory signal sequence at the amino terminus, a collagenous region (Gly-X-Y repeats), and a globular domain. The globular domain of adipoQ shares significant homology with subunits of complement factor C1q, collagen alpha 1(X), and the brain-specific factor cerebellin. The expression of adipoQ is highly specific to adipose tissue in both mouse and rat. Expression of adipoQ is observed exclusively in mature fat cells as the stromal-vascular fraction of fat tissue does not contain adipoQ mRNA. In cultured 3T3-F442A and 3T3-L1 preadipocytes, hormone-induced differentiation dramatically increases the level of expression for adipoQ. Furthermore, the expression of adipoQ mRNA is significantly reduced in the adipose tissues from obese mice and humans. Whereas the biological function of this polypeptide is presently unknown, the tissue-specific expression of a putative secreted protein suggests that this factor may function as a novel signaling molecule for adipose tissue.

3T3 Cells↗
PubMed1996

Regulation of S100P expression by androgen.

BACKGROUND: The growth and function the normal prostate is dependent on the presence of androgen. As prostate tumors progress there is a loss of androgen-dependent cell growth. The identification of the genes that are regulated by androgens may be of pathological and clinical significance. METHODS: In this study the differential display method was used to identify genes regulated by androgen in an androgen-responsive prostate cancer cell line, LNCaP-FGC. RESULTS: A gene whose expression is down-regulated in LNCaP-FGC cells after 30 hr of androgen deprivation has been identified. This gene is a previously identified member of the S100 gene family of calcium-binding proteins, namely S100P. Here we show that S100P expression is regulated by the synthetic androgen R1881, but not by serum growth factors. It is dysregulated in the androgen-independent prostate cancer cell lines LNCaP-R, DU145, and PC3. CONCLUSIONS: The data indicate that S100P may play a role in the etiology of prostate cancer.

Amino Acid Sequence↗
PubMed1996

Molecular genetic analysis of the 17p11.2 region in patients with hereditary neuropathy with liability to pressure palsies (HNPP).

Hereditary neuropathy with liability to pressure palsies (HNPP) is in most cases associated with an interstitial deletion of the same 1.5-Mb region at 17p11.2 that is duplicated in Charcot-Marie-Tooth type 1A (CMT1A) patients. Unequal crossing-over following misalignment at flanking repeat sequences (CMT1A-REP), either leads to tandem duplication in CMT1A patients or deletion in HNPP patients. With the use of polymorphic DNA markers located within the CMT1A/HNPP duplication/deletion region we detected the HNPP deletion in 16 unrelated HNPP patients, 11 of Belgian and 5 of French origin. In all cases, the 1.5-Mb size of the HNPP deletion was confirmed by EcoRI dosage analysis using a CMT1A-REP probe. In the 16 HNPP patients, the same 370/320-kb EagI deletion-junction fragments were detected with pulsed field gel electrophoresis (PFGE), while in CMT1A patients, a 150-kb EagI duplication-junction fragment was seen. Thus, PFGE analysis of EagI-digested DNA with a CMT1A-REP probe allows direct detection of the HNPP deletion or the CMT1A duplication for DNA diagnostic purposes.

Blotting, Southern↗
PubMed1996

Hypothalamic and olfactory control of sexual behavior and partner preference in male rats.

Sexually active male rats prefer a sexually receptive female to a nonreceptive female, and partner-preference tests provide one way of studying sexual motivation. Surgical deafferentation of the olfactory bulbs from all the known chemosensory systems of the nasal septum renders rats anosmic. In Experiment 1, we show that, although bulb deafferentation of male rats decreases some aspects of sexual performance, most deafferented males copulate and partner preference is not affected. In Experiment 2, we show that large excitotoxin lesions of the preoptic hypothalamus eliminate copulation, an effect that is correlated with damage to the anterior portions of the medial and lateral preoptic area. Lesions also decrease partner preference, an effect that is correlated (r = 0.82) with damage to a small part of the bed nucleus of the stria terminalis. Most males who do not copulate after hypothalamic lesions show a persistent, albeit reduced, preference for receptive females over nonreceptive females. This preference appears to depend on olfactory ability because bulb deafferentation of lesioned, noncopulating males virtually eliminates partner preference.

Animals↗
PubMed1996

Ultrasound-guided internal radiotherapy using yttrium-90-glass microspheres for liver malignancies.

UNLABELLED: Treatment of liver malignancies, in particular hepatocellular carcinoma, remains a serious problem because of the difficulty of delivering adequate therapeutic agents to the lesions while sparing the surrounding normal tissue. In an attempt to overcome this obstacle, intratumoral injection of 90Y, a beta-emitter, was performed. METHODS: Twenty-seven hepatocellular carcinomas and six liver metastases were studied, most of which had failed other therapeutic modalities. Guided by ultrasound, 90Y-glass microspheres (GMS) were carefully injected into predetermined tumor sites. The procedure was repeated at 3--4-wk intervals where indicated. Echographic, clinical and laboratory follow-up was conducted at regular intervals. RESULTS: Twelve to 32 mo after treatment, 27 patients were still alive, with dramatic improvement of their clinical condition: 90.6% of the tumor foci became smaller, with echogenic or blood flow changes on liver sonograms. Serum titers of alpha-FP in 10 of 13 patients returned to normal levels. Repeat biopsy in nine patients showed complete tumor destruction in eight. Six patients died of either end-stage disease or wide dispersion of the tumor. CONCLUSION: The intratumoral administration of 90Y-GMS under ultrasound guidance yielded a higher cure rate for liver malignancy with no severe side effects. The higher radiation dosage delivered by injected 90Y to the periphery of the lesions (up to 28,215-75,720 cGy) was thought to account for the successful outcome. These results show that intratumoral radionuclide injection is feasible for treatment of malignant lesions inside the body.

Adult↗
PubMed1996

[US-guided microwave in the treatment of liver cancer: experimental study and preliminary clinical application].

OBJECTIVE: To completely coagulate deep tumor and protect normal tissue by using microwave electrode is vivo and in vitro animal experimental study, under US-guided percutaneous microwave coagulation. METHOD: The Ultrasound Microwave Therapy-I (UMT-I) equipment was utilized at 2450 MHz in frequency. RESULTS: Microwave coagulation could produce a stable necrosis area of 2cm in diameter with irradiation at 60-80W for 60-180 seconds, and the corresponding temperature at its surrounding area was 61.95 +/- 5.81 degrees C. Microwave induced coagulation of tumor correlated well with the sonographic changes. The shape of coagulated area was elliptic when 27 mm or 9 mm of the inner conductor of electrode was exposed, and the temperature of the shaft of the electrode raised smaller and slowly based on our animal experimental study, 15 nodules of 12 patients with liver cancer were microwave-coagulated under US-guide. The temperature of tumor surrounding area raised to 54-69.5 degrees C during operation. After treatment, all lesions had smaller size, hypoechogenicity and disappearance of blood flow. AFP titer dropped in 7 patients and normalized in 4. CONCLUSION: US-guided microwave for the treatment of liver cancer is effective in coagulating deep tumor and protecting normal tissue.

Animals↗
PubMed1996

[Construction of shuttle vector containing delta-endotoxin gene of Bacillus thuringiensis].

The Bacillus thuringiensis toxin gene CryIA(c) was inserted into the shuttle vector pBE-2 to construct pAMY for expressing the B.t. gene in both Gram-negative and -positive bacterial systems. pAMY was introduced into wild type Bacillus cereus, B.brevis and B.subtilis by electroporation. Transformants containing delta-endotoxin gene produced proteins reacted with B.t. crystal protein antibody. Upon biological toxicity tests, the transformants gave a mortality of 100% against Ostrinia furnacilis, 58.8% against Heliothis armigera and 100% against Heliothis assulta. The ability of promoting plant growth of the original strains is retained.

Bacillus cereus↗