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J B Kopp

Publications and source records attributed to J B Kopp.

At least 55 records · Page 3Linked to original sources
PubMed1995

Role of angiotensin II in the expression and regulation of transforming growth factor-beta in obstructive nephropathy.

Unilateral ureteral obstruction (UUO) leads to fibrosis of the obstructed kidney. We tested the hypothesis that interstitial fibrosis in UUO results, at least in part, from enhanced expression of transforming growth factor-beta (TGF-beta) which in turn is regulated by local angiotensin II (Ang II) generation. (The generic name TGF-beta is used to discuss properties shared by all isoforms, but special reference to other isoforms is made when specifically needed.) Using Northern blot and immunohistochemical analysis, we examined the expression of TGF-beta in rat kidneys after 24 hours (aUUO) and one week (cUUO) of obstruction. Obstructed kidneys from both periods had increased interstitial and perivascular TGF-beta immunoreactivity compared to contralateral and sham kidneys, in which immunostaining was confined to the inner medulla. Relative abundance of all TGF-beta mRNA isoforms were higher in the obstructed than in contralateral and sham kidneys in both aUUO and cUUO. Expression of TGF-beta isoforms varied according to site (cortex vs. medulla), segment of the nephron, type of cells and duration of the obstruction. The increase in TGF-beta immunoreactivity and mRNA levels in aUUO and cUUO was almost totally abolished by pretreatment with losartan. We conclude that in UUO: (a) TGF-beta gene expression is increased and differentially regulated; (b) Ang II, at least partially, mediates the overexpression of TGF-beta gene; and (c) Ang II may play a central role in fibrogenesis in this and other models of tubulointerstitial disease.

Angiotensin II↗
PubMed1995

Transplantation of skin from human immunodeficiency virus type 1-transgenic mice to normal congenic mice results in graft rejection.

Skin from mice transgenic (Tg) for part of the human immunodeficiency virus type 1 (HIV-1) genome was transplanted onto normal mice of the same strain. All Tg grafts were rejected within 29 days. In contrast, skin from normal mice that was transplanted to HIV-1-Tg recipients remained viable for > 67 days. Histologic examination of Tg grafts on normal mice showed evidence of monocytic infiltrates. Monocytic infiltrates were not observed, however, when either normal or Tg skin was transplanted onto Tg mice. Immunohistologic staining verified the presence of gp120 protein expression in the Tg-transplanted skin but not in adjacent normal skin. It is concluded that the Tg mice are immunologically tolerant to the HIV-1 gene products they express.

Animals↗
PubMed1995

Derivation and application of upper limits for prostate specific antigen in men aged 50-74 years with no clinical evidence of prostatic carcinoma.

OBJECTIVE: To derive age-specific upper limits for prostate specific antigen (PSA) level in men 50-74 years of age with no clinical evidence of prostatic carcinoma, and to test the sensitivity and specificity for cancer detection of these upper limits. SUBJECTS AND METHODS: A total of 6166 men were recruited for a multicentre study of prostate cancer detection and underwent a serum PSA determination and digital rectal examination (DRE). Men considered to be clinically free of prostatic carcinoma were those with a normal DRE and a PSA level < or = 4.0 ng/mL, and men with an abnormality in either parameter who underwent ultrasonography-guided prostate biopsy that revealed no evidence of carcinoma. By these criteria, 5469 men had no evidence of prostatic carcinoma. Dividing the population into 5-year age increments, three statistical methods were assessed to derive upper limits for serum PSA level by age; the mean +2 SD, the 99th percentile, and a 97.5% prediction interval based on linear regression. RESULTS: Newly-derived upper limits calculated by each method in the 50-54 and the 70-74 age group were 3.9 ng/mL and 7.6 ng/mL (mean +2 SD), 5.2 ng/mL and 14.0 ng/mL (99th percentile), and 4.7 ng/mL and 8.2 ng/mL (97.5% prediction interval). The sensitivity of the newly-derived upper limits was tested using receiver operating characteristic curves derived from men with no suspicious findings on DRE and a serum PSA concentration > 4.0 ng/mL. Although the specificity of the test increased with increasing PSA upper limits, no upper limits derived from these three methods yielded adequate sensitivity to detect cancer; sensitivities by age range were from 53 to 94%, using mean +2 SD, from 25 to 50% with the 99th percentile, and from 47 to 64% with the 97.5% prediction interval. CONCLUSION: We do not recommend age-referenced adjustments in upper limits for serum PSA concentration, but recommend that an upper limit of 4.0 ng/mL be used in all men 50-74 years of age.

Aged↗
PubMed1995

Transgenic animal models of renal development and pathogenesis.

The use of transgenic animals represents a powerful tool with which to address the role of particular gene products in vivo. Recent technical and biological advances have simplified the process of creating both transgenic mice and null-mutation mice. Increasing numbers of genetic control elements are available to direct transgene expression to particular renal cell types and to enhance the consistency of expression. These approaches have contributed significantly to our understanding of renal development and pathogenesis, in particular in the following areas: the roles of various oncogenes, homeobox genes, and growth factors in renal development and the pathogenesis of cystic renal diseases; the contribution of systemic and local expression of the renin-angiotensin system to blood pressure control; the role of growth factors and cytokines in progressive glomerular disease; the role of viral proteins in the pathogenesis of glomerular and tubular disease; and mechanisms of immune-mediated renal disease.

Animals↗
PubMed1995

Transgenic models of HIV-1.

Transgenic technology has been very successful at providing insights into possible processes involved in HIV-induced pathogenesis. The availability of these small animal models for the study of HIV-related syndromes including KS, epidermal proliferative lesions, HIV-associated nephropathy, AIDS-related growth failure and cachexia may well facilitate the development of novel therapies for these complications. Other phenotypes created in mice, such as cataracts and hepatic cancer [59], may not have human analogies but may still provide insight into pathogenesis. Thus, transgenic models have already provided resources to study many manifestations of AIDS and others are likely to be developed. The optimal strategy for designing future transgenic animals, however, is less clear. No transgenic mouse model has been generated to date that will provide an avenue for vaccine development. This advance awaits the further discovery of the host factors that facilitate the virus replicative cycle in humans and a better understanding of these pathways in the mouse. For the development of molecular-based therapy, however, the currently available models may well be adequate to test molecular inhibitors of transcription [7,60,61] and post-transcriptional processing of viral mRNA [62]. Whether single or multigenic constructs under the control of the LTR are better or worse for this purpose is a debatable issue. Transgenic technology may yet make an additional contribution to the development of molecular therapy for AIDS. The best method of demonstrating that a gene therapeutic strategy is safe to administer to patients has not been determined. By introducing potentially therapeutic constructs into mice as transgenes, their safety can be assessed in many different cell types in vivo, analogous to toxicological testing in rodents for systemically administered drugs. Thus, transgenic technology has already provided insights into the pathogenesis of HIV-1. While it has not yet proven its utility for vaccine development, transgenic technology holds the promise of being an active participant in the development of both safe and effective gene therapy approaches for the treatment of AIDS.

AIDS Dementia Complex↗
PubMed1995

Mouse kalinin B1 (laminin beta 3 chain): cloning and tissue distribution.

BACKGROUND: Kalinin, an anchoring filament-associated protein, is a member of the laminin family which is believed to play a role in the attachment of particular epithelial cells to the basement membrane. EXPERIMENTAL DESIGN: A newborn mouse lung cDNA library was screened under low stringency conditions using as a probe a murine laminin beta 1 chain cDNA, an approach designed to identify novel laminin beta 1 chain homologs. RESULTS: We have identified a novel cDNA sequence comprising 4049 base pairs, with an open reading frame that potentially codes for 1168 amino acids, including a presumptive signal peptide. The gene was mapped to mouse chromosome 1. The amino acid sequence is homologous to laminin beta 1 and beta 2 chains, but is distinguished from these molecules by having a truncated short arm region. The sequence has considerable similarity to the human kalinin B1 chain (laminin beta 3), suggesting that it is murine beta 3 chain. Northern blot analysis demonstrated a single 4.0-kilobase species in the mouse newborn skin, lung, and Pam 212 cells. Immunolocalization studies using the 14-day embryo and adult mouse tissues demonstrated that the murine beta 3 chain is located at the dermal-epidermal junction of the skin and the basement membrane of the oral mucosa, oropharynx, and upper portions of the tracheobronchial tree. In situ hybridization studies of the mammary gland showed that the beta 3 mRNA chain was produced by the epithelial cells of the gland but not by the mesenchymal cells. Western blotting under nonreducing conditions using the antibody to beta 3 chain detected molecules of 400 and 440 kilodaltons (kDa) in the conditioned medium of human foreskin keratinocytes, A431 cells, and Pam 212 cells. Western blotting under reducing conditions detected only a single 140-kDa species, suggesting that beta 3 chain is present within disulfide-linked complexes. This 140-kDa species was contained in the kalinin complex immunoprecipitated by anti-kalinin B2 (laminin gamma 2) antibody from the conditioned medium of HT1080 cells, suggesting that both the beta 3 and gamma 2 chains are present in the multimeric complex. CONCLUSIONS: Murine laminin beta 3 chain shows considerable homology to the human homolog and has a tightly restricted tissue distribution, confined to the basement membrane of cells in contact with the external environment. In vitro studies indicate that the beta 3 chain participates in trimer formation with the gamma 2 chain and possibly with other laminin chains as well.

Amino Acid Sequence↗
PubMed1994

Patterns of HIV-1 mRNA expression in transgenic mice are tissue-dependent.

To explore tissue-specific factors that may be important in HIV-1 transcriptional and post-transcriptional regulation, we examined a transgenic mouse model containing a mutant provirus deleted in the gag and pol region. The level of transgene expression was tissue-dependent. Skin, muscle, and tail consistently expressed the transgene abundantly; intestine, kidney, and thymus exhibited variable but generally low levels of expression; while liver expression was undetectable by Northern analysis. Individual mRNAs within the family of singly and multiply spliced messages were determined by reverse transcription (rt) of RNA samples from mouse tissues, polymerase chain reaction (PCR) amplification, and Southern hybridization with exon-specific probes. The exact percentage of Tat-coding mRNA that was multiply spliced was also determined by competitive rtPCR. When 2-, 4-, or 7-kb (full-length) mRNA species were calculated as a percentage of the total mRNA, two phenotypes of distribution were detected. Lymphoid tissue (thymus and spleen) and kidney had significantly greater amounts of unspliced message (P < 0.001) regardless of the level of expression. All other tissues expressed the multiply spliced messages encoding Tat, Rev, and Nef predominantly. Furthermore, utilization of the three major second exon splice acceptor sites for tat, rev, and nef was the same in transgenic mice as has been demonstrated in human cells but the splice acceptor site for the vpu/env was different in murine tissue. The marked tissue-dependent patterns of HIV mRNA expression suggest a potential mechanism for the organ-specific manifestations of AIDS.

Alternative Splicing↗
PubMed1994

Growth failure and AIDS-like cachexia syndrome in HIV-1 transgenic mice.

The mechanisms which predispose to growth failure in infants and children infected with immunodeficiency virus type-1 (HIV-1) are not fully understood. The contributions of viral replication and CD4+ T cell depletion to growth failure in an HIV-1 transgenic mouse model were investigated. Mice homozygous for the transgene, a gag-pol deletion mutant of the HIV-1 provirus pNL4-3, exhibited marked cachexia, growth retardation, lymphoproliferation with a reduction in the percentage of CD4+ T cells but an increase in the absolute number of splenic CD4+ and CD8+ T cells, thymic hypoplasia, and early death. Despite the absence of T cells, athymic nude mice, homozygous for the HIV transgene, displayed comparable growth failure. The results indicate that AIDS-like cachexia may be produced by expression of viral envelope or accessory genes, need not be accompanied by absolute depletion of CD4+ T cells, and may occur independent of T cell function.

Acquired Immunodeficiency Syndrome↗
PubMed1994

bFGF and its low affinity receptors in the pathogenesis of HIV-associated nephropathy in transgenic mice.

HIV-associated nephropathy is characterized by extensive tubulointerstitial disease with epithelial cell injury, microcystic proliferation, and tubular regeneration with glomerulosclerosis. To explore the role of bFGF as a mediator of HIV-induced interstitial disease, we utilized an HIV transgenic mouse model that manifests clinical and histological features observed in patients. In transgenic mice, simultaneous renal epithelial cell proliferation and injury were detected in vivo. In areas of microcystic proliferation, immunoreactive bFGF colocalized with extracellular matrix. Kidneys from transgenic mice had increased bFGF low affinity binding sites, particularly in the renal interstitium. In vitro, transgenic renal tubular epithelial cells proliferated more rapidly and generated tubular structures spontaneously, in marked contrast to nontransgenic renal cells where these pathologic features could be mimicked by exogenous bFGF. These studies suggest that renal bFGF and its receptors play an important role in the pathogenesis of HIV-associated nephropathy.

AIDS-Associated Nephropathy↗
PubMed1994

Quantitative analysis of viral burden in tissues from adults and children with symptomatic human immunodeficiency virus type 1 infection assessed by polymerase chain reaction.

The amount of human immunodeficiency virus type 1 (HIV-1) in various tissues was investigated by polymerase chain reaction (PCR) in 16 patients with end-stage HIV-1 infection and 7 patients with symptomatic but less advanced disease. During postmortem study of the 16 end-stage patients, HIV-1 DNA was found most often in lymph nodes and the spleen (both 100%), lung (93.8%), and colon (87.5%). Biopsied lymph nodes from the 7 symptomatic patients contained substantially higher copy numbers of HIV-1 RNA and DNA than did peripheral blood mononuclear cells (PBMC). Plasma viral RNA levels correlated significantly with the amount of HIV-1 RNA in PBMC (r2 = .86, P = .0025) but not with the level of viral RNA in lymph nodes in patients with symptomatic HIV-1 infection. These data suggest that although lymph nodes represent the main site for HIV-1 infection and replication, the level of circulating viral burden may not be solely determined by the magnitude of active HIV-1 replication in lymph nodes.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Prostate specific antigen levels in men older than 50 years without clinical evidence of prostatic carcinoma.

In their derivation of normal prostate specific antigen (PSA) levels (0 to 4.0 ng./ml.) Hybritech used almost exclusively men less than 60 years old. The purpose of this study was to define PSA levels by age decade in men older than 50 years without clinical evidence of prostatic carcinoma or so-called cancer-free. We define the cancer-free population as men with a PSA less than or equal to 4.0 ng./ml. and nonsuspicious digital rectal examination, and those with an abnormality in either parameter with a nonmalignant prostate biopsy. A total of 755 men was recruited for a prostate cancer detection study using serum PSA and digital rectal examination, of whom 728 fulfilled our criteria of cancer-free. Newly derived mean and standard deviation were 1.32 +/- 1.10 ng./ml. in the 50 to 59-year group, 1.91 +/- 1.72 ng./ml. in the 60 to 69-year group and 2.36 +/- 1.98 ng./ml. in the 70 to 79-year group. The upper limits for PSA (mean+2 standard deviations) by age were 3.5 ng./ml. in the 50 to 59-year group, 5.4 ng./ml. in the 60 to 69-year group and 6.3 ng./ml. in the 70 to 79-year group. The apparent accuracy of these new limits is strong in the 60 to 69-year group but it declines in the next decade. The data support further attempts at using PSA, age and digital rectal examination to establish selection criteria for prostate biopsy with adequate sensitivity and specificity.

Age Factors↗
PubMed1993

Renal vascular induction of TGF-beta 2 and renin by potassium depletion.

Recently, we have found that transforming growth factor (TGF)-beta 2 and renin are abundantly expressed in the juxtaglomerular apparatus (JGA) of dehydrated mice. Since potassium (K+) depletion also stimulates renin and induces hypertrophy of the JGA, we examined the ability of this maneuver to stimulate TGF-beta isoforms and renin in renovascular tissue and the JGA of young rats. Sprague-Dawley rats (50 +/- 5 g) were fed either a control diet or a potassium-deficient diet (< 0.05% K+) for 7, 16, or 21 days. As a control for TGF-beta and renin stimulation, an additional group of animals was fed a normal diet but was water deprived for three days. Potassium-depleted animals experienced severe growth retardation but kidney weight increased significantly. Potassium depletion induced both TGF-beta 2 and renin immunoreactivity in renal arterioles and the JGA but had no effect on TGF-beta 1 and TGF-beta 3 isoforms. To determine the role of circulating angiotensin II in the stimulation of TGF-beta 2 by potassium depletion, a group of potassium-depleted rats received enalapril (100 mg/liter) in the drinking water. The addition of converting enzyme inhibitor increased both the intensity of TGF-beta 2 and renin staining as well as the number of cells positively stained. Our results demonstrate that K+ depletion induces TGF-beta 2 and renin in renal arterioles and in the JGA. Furthermore, circulating angiotensin II is not responsible for the increase in the local expression of TGF-beta 2. These findings suggest that TGF-beta 2 may be an important mediator of JGA hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Cutaneous disorders and viral gene expression in HIV-1 transgenic mice.

Patients infected with HIV-1 experience several hyperproliferative skin disorders, including seborrheic dermatitis, ichthyosis, and psoriasis. Transgenic mice carrying a subgenomic HIV-1 proviral construct lacking the gag and pol genes were found to develop proliferative epidermal lesions, manifested as diffuse epidermal hyperplasia in homozygous transgenic mice and benign papillomas in heterozygous transgenic mice. Nonpapillomatous skin from both homozygotes and heterozygotes expressed viral RNA, and the viral envelope protein gp120 was localized to the suprabasal keratinocyte. Papillomas contained increased amounts of both viral mRNA and envelope glycoprotein. Exposure of transgenic mice to doses of ultraviolet B (UV-B) irradiation that induced cutaneous injury increased viral gene expression and resulted in the development of papillomas within 14-21 days. Cutaneous injury induced by phenol and liquid nitrogen had similar effects. These data support a role for HIV-1 gene products in the pathogenesis of proliferative epidermal disorders associated with HIV-1 infection. Further, they suggest that the process of wound repair increases HIV-1 gene expression in this transgenic mouse model.

Animals↗
PubMed1993

Extracellular matrix gene expression in experimental glomerulonephritis.

Recent studies using animal models of glomerulonephritis indicate that steady-state levels of mRNAs encoding basement membrane proteins are frequently, but not universally, increased in parallel and that mRNAs encoding interstitial matrix proteins represent a separate set of genes that may also display coordinate regulation. A variety of maneuvers that ameliorate progressive glomerulosclerosis may act, at least in part, by suppressing glomerular cell matrix protein gene expression. The observed coordinate regulation of matrix genes may be a consequence of shared genetic regulatory sequences. Future therapies designed to retard glomerulosclerosis may take advantage of similarities among the extracellular mediators and regulatory sequences that influence matrix gene expression.

Animals↗
PubMed1992

Progressive glomerulosclerosis and enhanced renal accumulation of basement membrane components in mice transgenic for human immunodeficiency virus type 1 genes.

Patients infected with human immunodeficiency virus type 1 (HIV-1) develop a renal syndrome characterized by proteinuria, renal failure, and focal segmental glomerulosclerosis. By using a noninfectious HIV-1 DNA construct lacking the gag and pol genes, three transgenic mouse lines have been generated that develop a syndrome remarkably similar to the human disease. In the present study, we have characterized in detail one of these lines, Tg26. In Tg26 mice, proteinuria was detectable at approximately 24 days of age, followed by severe nephrotic syndrome and rapid progression to end-stage renal failure. Renal histology showed focal segmental glomerulosclerosis and microcystic tubular dilatation. Indirect immunofluorescence studies demonstrated increased accumulation of the basement membrane components laminin, collagen type IV, and heparan sulfate proteoglycan. The viral protein Rev was present in sclerotic glomeruli. Northern blot analysis of total renal RNA showed expression of viral genes prior to the appearance of histologic renal disease, with greatly diminished viral gene expression late in the disease course. Kidneys from transgenic mice expressed increased steady-state levels of collagen alpha 1(IV) mRNA when glomerulosclerosis was present. We conclude that the presence of HIV-1 genes is associated with progressive renal dysfunction and glomerulosclerosis in transgenic mice.

Animals↗
PubMed1992

Renal tubular epithelial cells express osteonectin in vivo and in vitro.

Osteonectin (SPARC, culture shock protein, BM-40) is a widely distributed glycoprotein which binds calcium and several extracellular matrix proteins, including interstitial collagens and thrombospondin, but whose physiologic role remains undefined. In the present studies, we have demonstrated that immunoreactive osteonectin is present in the distal cortical tubule and medullary tubules of murine kidney. We surveyed the renal epithelial cell lines LLC-PK1, MDCK, and OK for the expression of mRNA encoding osteonectin. We found that osteonectin mRNA is expressed by LLC-PK1 and OK cells but not by MDCK cells, as well as by adult kidney from several species. Calcitonin and vasopressin, agents which increase cAMP in these cells, were found to decrease steady-state osteonectin mRNA concentrations. We found that LLC-PK1 cells produced osteonectin protein, that the protein was localized to intracellular granules, and that the protein bound hydroxyapatite in vitro. Pulse-chase analysis revealed that osteonectin was secreted from the cell layer to the medium after a lag time of four to six hours and was secreted preferentially from the basolateral domain of the cell. The preferential secretion of the calcium-binding protein osteonectin from the renal epithelial cell is consistent with several possible functions, including a structural extracellular matrix protein, a participant in transepithelial ion transport, and an inhibitor of extracellular calcification.

Animals↗