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Biomedical subjects

J J Li

Publications and source records attributed to J J Li.

At least 109 records · Page 6Linked to original sources
PubMed1995

Human herpesvirus-like nucleic acid in various forms of Kaposi's sarcoma.

The association between a new human herpesvirus-like agent and various forms of Kaposi's sarcoma was examined by PCR. The DNA sequences of this agent were detected in 7 of 8 classic Kaposi's sarcoma specimens, 12 of 12 AIDS-associated specimens from the United States, and 7 of 10 specimens from African endemic Kaposi's sarcoma. Polymorphism of the herpesvirus-like DNA in the Kaposi's tissue from different populations was observed by both single-strand conformational polymorphism and direct sequencing. Furthermore, the presence and expression of the virus was detected in some Kaposi's tumours by Southern and northern blotting. This herpesvirus may be involved in the pathogenesis of different kinds of Kaposi's sarcoma seen among distinct and unrelated populations.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Eukaryotic DNA replication.

Recent discoveries suggest that the initiation of eukaryotic DNA replication involves at least two steps--one occurring near the completion of mitosis and the other at the onset of S phase--that bring about the ordered assembly of initiator proteins at the origin. The identification and characterization of components involved in promoting or antagonizing each of these steps has provided a preliminary understanding of how replication initiation is regulated so precisely during the cell cycle.

Animals↗
PubMed1995

Quantitative analysis of repeat adenovirus-mediated gene transfer into injured canine femoral arteries.

We quantitatively evaluated the effectiveness of a repeat administration of a recombinant adenoviral vector expressing bacterial Escherichia coli lacZ into the same arterial site of a relatively large animal, the dog. The replication-defective adenoviral vector was introduced percutaneously into balloon-injured femoral arteries through a double-balloon catheter. After a single dose of adenoviral vector, up to 90% of surface (73 +/- 16%, n = 7) and smooth muscle cells in multiple layers of the media showed transgene expression as evaluated by 5-bromo-4-chloro-3-indoyl beta-D-galactopyranoside histostaining without extralocal expression, as assessed by polymerase chain reaction. High-level expression (measured as beta-galactosidase activity) peaked 7 days after transfer and was transient, although it was retained for a month. Second does of the same adenovirus to the same arterial site were given 1, 2, 5, or 8 weeks after the first administration. At 1 week the second dose significantly enhanced lacZ expression. At 2, 5, or 8 weeks the second dose reinduced lacZ expression at 25% to 30% of the full expression. lacZ expression was also detected in preimmuned dogs, although the expression levels correlated inversely to the titer of neutralizing antibodies in their serum. These results demonstrate that arterial gene expression can be enhanced by a second administration of the same adenovirus after a short interval and that a repeat dose after a long interval partially but significantly reinduces gene expression despite the presence of an immune response. These data may provide an additional scientific foundation for the use of adenovirus-mediated arterial gene transfer in future clinical practice.

Adenoviridae↗
PubMed1995

Percutaneous transluminal gene transfer into canine myocardium in vivo by replication-defective adenovirus.

OBJECTIVE: The aim was to examine the feasibility, efficiency and safety of adenovirus-mediated in vivo gene transfer into the canine myocardium by a percutaneous transluminal method using a needle-catheter. METHODS: Either a replication-defective adenovirus (Adex1SRLacZL) or a plasmid (pSRLacZ), both expressing E. coli lacZ coding beta-galactosidase (beta-gal), was directly injected into the left ventricle of dogs through a needle-catheter inserted via a femoral artery. Expression of lacZ was examined by histochemical staining and quantified by measuring beta-gal activity. RESULTS: Injections with Adex1SRLacZL induced lacZ expression as a result of 40 out of 41 injections; the expression level was 10 times higher than that obtained with pSRLacZ. Induced beta-gal activity was detected within 24 h, peaked at 7 days and retained for 2 weeks after gene transfer. A repetitive administration of the same adenovirus at 14 days after the first injection also evoked a reduced but significant level of expression despite neutralizing antibodies to adenovirus in serum. Although injection induced an inflammatory response that peaked at 3 days after injection and gradually subsided without a second peak, the temporal change and the extent of inflammation induced by adenovirus injection was not significantly different from those induced by injection with either saline or plasmid. Neither leakage of enzymes such as CPK or LDH nor alteration in the ECG was detected in the 30 days following gene transfer. CONCLUSIONS: Our findings demonstrate that a catheter-mediated direct injection with an adenovirus can induce gene expression in the ventricle more efficiently without additional myocardial damage and inflammation compared with injection with a plasmid. A repeat dose of the same adenovirus elicited gene expression at an attenuated but significant level. This method may potentially have clinical applications: in modifying myocardial phenotype and/or improving general circulation under certain circumstances.

Adenoviridae↗
PubMed1995

Adenovirus-mediated arterial gene transfer does not require prior injury for submaximal gene expression.

We investigated whether gene expression in arterial wall following adenovirus-mediated gene transfer would be enhanced by prior injury. We introduced Escherichia coli lacZ into the balloon-injured canine femoral arteries through a double-balloon catheter by either a replication-defective adenovirus or liposome-mediated transfection (lipofection) using an expression plasmid, and quantified beta-galactosidase activity in arterial homogenates harvested 5 days after gene transfer. Gene expression by lipofection was enhanced six-fold when gene transfer was performed at 3 days, instead of 0 days after injury. However, gene expression achieved by adenovirus infection was not significantly changed irrespective of when gene transfer was performed between 0 and 12 days after injury, and beta-galactosidase activity was 25-fold higher than the enhanced value obtained by lipofection performed 3 days after injury. Our study indicates that submaximal gene expression in arterial wall can be achieved when adenovirus-mediated gene transfer is performed at the same time as angioplasty.

Adenoviridae↗
PubMed1994

Induction of chromosome aberrations in Syrian hamster renal cortical cells by various estrogens.

Estrogens, both natural and synthetic, have been implicated in carcinogenesis at different organ sites in a variety of animals, including man, for more than six decades. However, the molecular mechanism(s) involved in the carcinogenic action of estrogens still remains both controversial and elusive. Cytogenetic damage in the hamster kidney has been studied after in vivo treatment with either potent or weak estrogens for varying periods. Compared to age-matched untreated control, diethylstilbestrol (DES) treatment resulted in significant increases in the number of chromatid gaps and breaks, chromosome breaks, and endoreduplicated cells in hamster renal cortical cells. These chromosomal aberrations (CA) were cumulative with continued hormone exposure from 1.0 to 5.0 months. However, chromosome exchanges as a result of the breaks were not elevated. After 5.0 months of hormone treatment, potent estrogens such as 17 beta-estradiol and Moxestrol exhibited similar frequencies of CA in the hamster kidney to that found for DES, whereas weak estrogens such as 17 alpha-estradiol and beta-dienestrol exhibited CA frequencies that were not significantly different from untreated levels. Ethinylestradiol treatment for a similar period resulted in significant increases in chromatid gaps, although these did not evolve into increases in either chromatid or chromosome breaks, and in a rise in endoreduplicated cells. These results raise the possibility that the CA generated after estrogen treatment may be involved in renal tumorigenic processes.

Analysis of Variance↗
PubMed1994

Differential expression of advanced glycosylation end-products in neurons of different species.

The developmental time course and life span of the human brain are different from those of laboratory animals. These variations may be the reflection of metabolic differences of the neurons between different species. Using immunocytochemistry, we show that pyramidal neurons accumulate advanced glycosylation end products (AGEPs) formed by the Maillard reaction. However, the patterns of AGEPs accumulation in the pyramidal neuron were quite distinct between human and the 4 different animal species (horse, calf, pig, and rat) examined. In the human pyramidal neuron, AGEPs depict a granular, perikaryonal distribution, whereas in the animal brains, AGEPs show a nuclear staining pattern. The different patterns of AGEPs distribution in the pyramidal neurons suggest that AGEPs is an in vivo biochemical marker which distinguishes human pyramidal neurons from those of animals, and may help characterise pathologies specific to human.

Animals↗
PubMed1994

Rearrangement and expression of MDM2 oncogene in chronic lymphocytic leukemia.

Since trisomy 12 is the most common chromosome abnormality found in CLL and MDM2 has been mapped to this chromosome, we examined the possible association of MDM2 in the pathogenesis of CLL. A rearrangement of the MDM2 gene was observed in 4 of 11 peripheral blood mononuclear cells (PBMC) from patients with CLL by Southern blot hybridization. Expression of MDM2 was detected in all of the CLL samples examined by Northern blot. However, neither gross amplification nor overexpression of the MDM2 gene was found in CLL. The data suggest that MDM2 may play a role in the pathogenesis of CLL and may help to explain how abnormalities of chromosome 12 are related to CLL.

Blotting, Northern↗
PubMed1994

Characterization of the human bone sialoprotein (BSP) gene and its promoter sequence.

Bone sialoprotein (BSP) is a major structural protein of the bone matrix that is specifically expressed by fully-differentiated osteoblasts. To characterize the gene and to study the tissue-and differentiation stage-specific regulation of BSP gene transcription we have isolated and partially sequenced two overlapping genomic fragments which span the complete human BSP gene and its promoter region. The approximately 15 kb gene comprises seven exons of 82 bp, 68 bp, 51 bp, 78 bp, 63 bp, 159 bp and 2.5 kb (1-7, respectively), separated by six introns of approximately 3 kb, 92 bp, 95 bp, approximately 3 kb, approximately 0.5 kb and approximately 4.5 kb. All of the intron-exon boundaries defining the splice sites conform to the consensus sequence of: AG at the 3' splice site; and GT at the 5' splice site, except the 3' splice site of exon 1. The first exon encodes the 5'-UTR, the second exon the signal sequence and the first two amino acids, exons 3 and 4 the Tyr-and Phe-rich amino terminus, and exon 5 the first segment of polyglutamic acid. Exon 7 encodes over half of the protein including a second polyglutamic acid segment, the RGD cell attachment motif, the sulphated tyrosine-rich C-terminus and the 3'-UTR. The promoter region is characterized by an inverted TATA-like sequence (TTTATA), nts -28 to -23 from the transcriptional start site (+1), and an inverted CCAAT box (ATTGG) at -54 to -50. Analysis of chimeric constructs fused to a CAT reporter gene indicate that the presence of both the inverted TATA-like sequence and CCAAT elements are required for basal promoter activity. Comparison of the human BSP promoter with the rat BSP promoter (Li and Sodek, 1993) reveal that the nature and position of the inverted TATA-like sequence and CCAAT box together with an Ap1 (-148 to -142), CRE (-122 to -116) and a homeobox-binding site (-200 to -191) have been conserved. A putative Glucocorticoid Response Unit (GRU) consisting of a Glucocorticoid Response Element (GRE) and an overlapping direct repeat (DR5) similar to the retinoic acid receptor element (RARE) is present at -1038 to -1022. These studies have defined the structure of the human BSP gene and have identified novel transcriptional elements in the promoter that may be involved in the developmentally regulated, tissue specific expression of this gene.

Amino Acid Sequence↗
PubMed1994

Serum and tissue levels of estradiol during estrogen-induced renal tumorigenesis in the Syrian hamster.

The estrogen-induced renal tumor in the hamster has emerged as a major animal model in hormonal carcinogenesis. However, a fundamental aspect of this experimental model has as yet not been investigated. In the present study, comparisons between the serum and tissue 17 beta-estradiol (E2) levels in cyclic female hamsters and corresponding hormone levels in E2-treated castrated male hamsters have been made. Data is provided concerning the concentration of estrogenic hormones in the serum and target tissue typically required to elicit renal tumorigenesis in this species. Serum E2 levels in the cyclic female hamster average 79 pg/ml on days 1-2 and 311 pg/ml on days 3-4, attaining a maximum of 358 pg/ml on day 4 of the cycle. Elevation in uterine, renal and hepatic E2 tissue levels during days 3-4 of the cycle reflect increases in serum E2 levels which were 3.0-, 2.0-, and 2.6-fold higher when compared to day 1 of the cycle in these tissues. As expected, serum E2 levels of untreated castrated male hamsters did not appreciably vary over a 6 month period of aging and averaged about 32 pg/ml. Under conditions which produced essentially 100% renal tumor incidence, a rapid rise in serum E2 levels, averaging 71.0-fold higher than untreated castrated levels, was seen. A steady state serum E2 level of 2400 to 2700 pg/ml was maintained from 45-180 days of continuous estrogen treatment. Compared to kidneys of untreated hamsters, renal E2 levels in E2-treated hamsters rose only on average 5.4-fold between 15-180 days of hormone exposure. Serum levels of E2-treated hamsters were 5.7- to 8.0-fold higher than those observed in cyclic female hamsters on days 3 and 4. However, at these higher E2-treated serum levels there was no apparent effect either on weight loss or mortality of the animals.

Animals↗
PubMed1994

Paternity identification in twins with different fathers.

If a female has sexual intercourse with two males at short intervals within the same ovulatory period, superfecundation may occur. This article reports two cases of paternity identification in twins. The results showed that each twin had come from a different father. Thus, great attention should be paid to such a situation when the twin paternity identification is asked for.

Blood Grouping and Crossmatching↗
PubMed1994

Apolipoprotein (a) phenotypes in cardio-cerebrovascular diseases.

Apolipoprotein (a) [Lp(a)] phenotypes of 69 myocardial infarction survivor and 56 stroke patients were reported and compared to those of 190 healthy Chinese. The results revealed that the distributions of apo(a) phenotype frequency in patients with cardio-cerebrovascular disease (CCVD) were different from those of controls. The frequency of the phenotypes S1 and S2 were remarkably higher in patients than in controls within the same single-band apo(a) phenotype. Moreover, the Lp (a) serum concentrations in CCVD patients were significantly higher than in controls within the same single-band apo (a) phenotype. The apo (a) phenotype analysis of two pedigrees were shown as a typical autosomal dominant inheritance.

Adult↗
PubMed1993

Isolation of ORC6, a component of the yeast origin recognition complex by a one-hybrid system.

Here a method is described to identify genes encoding proteins that recognize a specific DNA sequence. A bank of random protein segments tagged with a transcriptional activation domain is screened for proteins that can activate a reporter gene containing the sequence in its promoter. This strategy was used to identify an essential protein that interacts in vivo with the yeast origin of DNA replication. Matches between its predicted amino acid sequence and peptide sequence obtained from the 50-kilodalton subunit of the yeast origin recognition complex (ORC) established that the gene isolated here, ORC6, encodes this subunit. These observations provide evidence that ORC recognizes yeast replication origins in vivo.

Amino Acid Sequence↗
PubMed1993

Expression of fibroblast growth factors and their receptors in acquired immunodeficiency syndrome-associated Kaposi sarcoma tissue and derived cells.

BACKGROUND: Fibroblast growth factors (FGF), such as basic FGF, have been implicated in the development of Kaposi sarcoma (KS) in vitro. The expression of several genes of the FGF family and their receptors in KS tumor lesions and KS-derived cells were evaluated. METHODS: Cultures of KS-derived cells were established. The expression of FGF family members and their receptors in these cells and in fresh biopsies from KS tumors was evaluated by reverse transcription polymerase chain reaction (RTPCR). The RTPCR products were confirmed by nucleotide sequencing. RESULTS: The expression of basic FGF and FGF receptor-1 (flg) was detected in all the samples tested. Acidic FGF (aFGF) and FGF-5 were detected in two of six and four of six KS tumor specimens, respectively, whereas both of these growth factors were expressed in all of the cell cultures, including six KS-derived cell cultures and human endothelial cells and smooth muscle cells. FGF-6 was expressed in two of six KS tumor specimens, but was not expressed in any of the cultured KS cells. Like flg, bek was expressed in all tissue samples and KS-derived cell cultures except in one KS specimen obtained from the patient's tongue showing expression of a high level of FGF-6. CONCLUSIONS: These results suggest that the expression of FGF in KS tumors with the coexpression of FGF receptors may provide a basis for autocrine and paracrine mechanisms contributing to the development of KS.

AIDS-Related Complex↗
PubMed1993

Cloning and characterization of the rat bone sialoprotein gene promoter.

To study the transcriptional regulation of the rat bone sialoprotein (BSP) gene, the nucleotide sequence of a approximately 1 kb HindIII/KpnI subfragment from a genomic clone containing the 5' flanking sequence, exon 1 and part of intron 1 was determined and the transcription start site defined. This region includes an inverted TATA element (nt -24 to -19), an inverted CCAAT box, a homeobox-binding site, a putative 1,25-dihydroxyvitamin D3 response element (VDRE) sequence overlapping the inverted TATA sequence, and a novel 18 nt palindrome that may control the tissue-specific transcription of the BSP gene. The shortest promoter sequence capable of directing bacterial chloramphenicol acetyltransferase reporter gene expression included the inverted TATA element and the inverted CCAAT box. However, the promoter activity was down-regulated by 1,25-dihydroxyvitamin D3, indicating that the unique VDRE-like sequence overlapping the TATA element is functional. Thus the rat BSP gene promoter is characterized by novel cis-acting elements that may be involved in hormone- and tissue-specific regulation of transcription.

Animals↗
PubMed1993

In vitro characterization of estrogen induced Syrian hamster renal tumors: comparison with an immortalized cell line derived from diethylstilbestrol-treated adult hamster kidney.

Primary diethylstilbestrol-induced kidney tumors from Syrian hamsters were grown in vitro and maintained in culture for 6 mo. Combined immunohistochemical studies using antibodies to intermediate filaments and ultrastructural studies of tumor cells in culture exhibited characteristics similar to tumor cells in vivo. Furthermore, the cells manifested transformed properties in culture; they grew both as multilayered colonies attached to the tissue culture substrate and as floating multicellular colonies (spheroids). When cultured cells were injected into diethylstilbestrol-treated recipient hamsters, tumors developed at the injection sites. In contrast, renal tubules or whole kidney cortex from control hamsters cultured in the same medium underwent only short-term growth, with senescence developing after approximately 1 mo. However, cell cultures of kidney cortex from animals treated in vivo for 5 mo. with diethylstilbestrol formed a cell line. This diethylstilbestrol-induced cell line has been maintained in culture for 1.5 yr and has the following characteristics: a) it is anchorage-dependent, b) it is negative in in vivo tumorigenicity tests, and c) cultured cells are histochemically and ultrastructurally similar to cultured tumor cells. This culture system should prove to be of use in studying hormonal carcinogenesis in vitro.

Animals↗