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Biomedical subjects

J Clements

Publications and source records attributed to J Clements.

At least 37 records · Page 2Linked to original sources
PubMed1999

The human tissue kallikreins (KLKs 1-3) and a novel KLK1 mRNA transcript are expressed in a renal cell carcinoma cDNA library.

Renal cell carcinoma (RCC) is the most common form of kidney cancer, for which there is no biochemical marker. We and others have previously shown that a prostate specific antigen (PSA)-like protein is elevated in the serum of women with RCC. PSA is a member of the tissue kallikrein (KLK) gene family of enzymes. We have constructed a RCC cDNA expression library and screened it for PSA and KLK expression to determine whether they may be responsible for this PSA-like activity. Since immunoscreening of the RCC library for expressed PSA-like proteins was unsuccessful, polymerase chain reaction (PCR) analysis of the RCC cDNA library was performed using universal KLK primers, directed to the common regions in exon 3 and exon 5 of KLK1, KLK2 and KLK3. Sequences identical to all three KLKs were present in the RCC cDNA library. In addition, a novel KLK1 transcript with a 104 base pair deletion in exon 4 that predicted a C terminal sequence minus the crucial Ser190, was detected. The role of these tissue kallikreins in RCC and the significance of the variant KLK1 transcript is yet to be established. It is still unclear which of these gene products, if any, was detected in the sera of the women with RCC.

Alleles↗
PubMed1999

Localization of bradykinin B2 receptors in the endometrium and myometrium of rat uterus and the effects of estrogen and progesterone.

In the uterus, bradykinin is a potent inducer of smooth muscle contraction, which is mediated by the bradykinin B2 receptor subtype. However, little is known about the distribution or regulation of this receptor in this tissue. The aim of this study was to localize the B2 receptor in the uterus and determine whether the levels of this receptor were altered during the estrous cycle and modulated by estrogen and/or progesterone in ovariectomized rats. At diestrus, uterine B2 receptors were localized to both the circular and longitudinal smooth muscle layers of the myometrium, the endometrial stroma, the glandular epithelium, and the layer subjacent to the luminal epithelium. B2 receptor levels in both myometrium and endometrium were lowest during early proestrus, when estrogen levels are low, whereas myometrial B2 receptor protein and messenger RNA levels were highest during late proestrous, when estrogen levels peak. Similar findings were observed for the estrogen-supplemented group after ovariectomy, with progesterone appearing to inhibit the estrogen-induced rise in bradykinin B2 receptor density in estrogen/progesterone-treated animals. Using in vitro receptor autoradiography employing the specific B2 receptor antagonist analog, HPP-HOE140, immunostaining with specific antipeptide antibodies generated against the B2 receptor, and in situ hybridization using a specific bradykinin B2 receptor riboprobe, our findings show a discrete distribution of the bradykinin B2 receptor throughout the different layers of the uterus and suggest that bradykinin B2 receptor levels in the rat uterus are regulated by estrogen, and possibly progesterone, in both myometrium and endometrium.

Animals↗
PubMed1999

Interferon-beta inhibits activated leukocyte migration through human brain microvascular endothelial cell monolayer.

Perivascular leukocyte infiltration into the central nervous system is characteristic of multiple sclerosis (MS) pathology. Interferon-beta (IFN-beta) has shown efficacy in the treatment of patients with MS, but the relevant mechanisms remain incompletely understood. In this study the effects of IFN-beta on leukocyte transendothelial migration were investigated using cells relevant to MS pathogenesis, namely human brain microvascular endothelial cells (HB-MVEC). Activated, but not resting leukocytes exhibited a high transendothelial migration capacity. HB-MVEC prestimulated with tumor necrosis factor (TNF) and IFN-gamma significantly promoted leukocyte transendothelial migration. IFN-beta inhibited the activated leukocyte transendothelial migration on TNF/IFN-gamma-activated HB-MVEC in a dose-dependent manner. A matrix metalloproteinase (MMP) inhibitor and monoclonal antibodies to lymphocyte function antigen-1 (LFA-1) or intercellular adhesion molecule-1 (ICAM-1), but not to very late antigen-4 or to vascular cell adhesion molecule-1 significantly inhibited the transendothelial migration of stimulated leukocytes, suggesting that this phenomenon involves the LFA-1/ICAM-1 interaction and MMP. However IFN-beta did not interfere with the binding of leukocytes to HB-MVEC unless IFN-beta was preincubated with leukocytes or added to HB-MVEC at the time of stimulation. Furthermore IFN-beta did not modulate the expression of adhesion molecules on either stimulated leukocytes or activated HB-MVEC, but partially reduced TNF and interleukin-1 production from stimulated leukocytes during coculture with HB-MVEC. Interestingly, in the presence of IFN-beta, a significant down-regulation of MMP-9 release from stimulated leukocytes was found, especially for the activated form of MMP-9. These results indicate that inhibition of leukocyte transendothelial migration is an important mechanism accounting for the beneficial effects of IFN-beta in the treatment MS patients.

Brain↗
PubMed1998

Altered surfactant homeostasis and alveolar type II cell morphology in mice lacking surfactant protein D.

Surfactant protein D (SP-D) is one of two collectins found in the pulmonary alveolus. On the basis of homology with other collectins, potential functions for SP-D include roles in innate immunity and surfactant metabolism. The SP-D gene was disrupted in embryonic stem cells by homologous recombination to generate mice deficient in SP-D. Mice heterozygous for the mutant SP-D allele had SP-D concentrations that were approximately 50% wild type but no other obvious phenotypic abnormality. Mice totally deficient in SP-D were healthy to 7 months but had a progressive accumulation of surfactant lipids, SP-A, and SP-B in the alveolar space. By 8 weeks the alveolar phospholipid pool was 8-fold higher than wild-type littermates. There was also a 10-fold accumulation of alveolar macrophages in the null mice, and many macrophages were both multinucleated and foamy in appearance. Type II cells in the null mice were hyperplastic and contained giant lamellar bodies. These alterations in surfactant homeostasis were not associated with detectable changes in surfactant surface activity, postnatal respiratory function, or survival. The findings in the SP-D-deficient mice suggest a role for SP-D in surfactant homeostasis.

Animals↗
PubMed1998

Production and characterization of SIV envelope-specific rhesus monoclonal antibodies from a macaque asymptomatically infected with a live SIV vaccine.

Five rhesus monoclonal antibodies (RhMAbs) were produced by rhesus EBV transformation of peripheral blood B cells from a rhesus macaque that had been asymptomatically infected with an attenuated, macrophage-tropic SIV strain, 17E-Cl. These MAbs recognized conformation-dependent epitopes on SIV gp120 and could not be mapped using synthetic peptides. All five RhMAbs were able to neutralize the vaccine strain and a heterologous isolate, SIV/DeltaB670. The RhMAbs did not cross-react with HIV-2; by contrast, four human MAbs derived from an HIV-2-infected person were broadly cross-reactive with both SIV and HIV-2 gp120s. Cross-competition analysis indicated that the five RhMAbs could be placed in two groups recognizing two nonoverlapping epitopes; while the HMAbs were placed in two additional competition groups. Binding of the three group I RhMAbs (1.7F, 3.11B, and 1.10A) as well as HMAb 17A was shown to be sensitive to specific amino acid alterations in V4 occurring in natural env variants. The results of this study demonstrate that RhEBV transformation provides a means to probe rhesus antibody responses to SIV infection at the monoclonal level. RhMAbs will allow structural and functional studies of envelope glycoprotein determinants that elicit protective immune responses against SIV.

Amino Acid Sequence↗
PubMed1998

Recommendations for spacing of test chemical concentrations in the mouse lymphoma tk mutation assay (MLA)

Recent test guidelines for the mouse lymphoma tk mutation assay (MLA) have highlighted the need to achieve 80-90% reduction in cell survival for a valid, robust assay with toxic chemicals. For many pharmaceuticals, under new ICH recommendations, this may be the only in vitro mammalian cell test that is performed. It was important to discover, therefore, how critical it is to achieve 80-90% toxicity, and how best to select the number and spacing of test concentrations to fulfil this requirement. We analysed data from 121 positive chemicals, provided by nine industrial and commercial laboratories, and found that for 17 chemicals (14%), the response profiles were so steep that using a conventional 2-fold dilution series of test concentrations would have failed to identify the active range (> 90% toxicity at one concentration, and no significant mutation at 50% of this dose), and positive responses would have been missed. Analysis of genotoxicity results in other test systems with these 17 chemicals revealed no differences in overall response profiles from the 104 chemicals that exhibited less steep MLA responses. The MLA results were therefore deemed to be equally biologically relevant. From this analysis, it is recommended that concentration spacing in the MLA needs to be closer than that obtained with a 2-fold dilution series, and a dilution factor where each concentration is 0.75 or 0.8 of the one above is recommended to identify the active range of positive mutagens.

Animals↗
PubMed1998

The TIMP2 membrane type 1 metalloproteinase "receptor" regulates the concentration and efficient activation of progelatinase A. A kinetic study.

We have used C-terminal domain mutants to further define the role of interactions of progelatinase A and membrane type 1 matrix metalloproteinase (MT1 MMP) in the binding of TIMP2 and in the cell-associated activation of progelatinase A. Soluble constructs of MT1 MMP were used to demonstrate that binding with TIMP2 occurs primarily through N-terminal domain interactions, leaving the C-terminal domain free for interactions with progelatinase A. The rate of autolytic activation of progelatinase A initiated by MT1 MMP cleavage could be potentiated by concentration of the proenzyme by binding to heparin. Residues 568-631 of the progelatinase A C-terminal domain are important in formation of the heparin binding site, since replacement of this region with the corresponding stromelysin-1 sequence abolished binding to heparin and the potentiation of activation. The same region of gelatinase A was required for binding of latent and active enzyme to TIMP2, but residues 418-474 were not important. A similar pattern was seen using cell membrane-associated MT1 MMP; residues 568-631 were required for binding and activation of progelatinase A, whereas residues 418-474 were not. Neither region was required for activation in solution. The addition of TIMP2 to HT1080 membrane preparations expressing MT1 MMP, but depleted of endogenous TIMP2, resulted in potentiation of progelatinase A activation. This effect was dependent upon TIMP2 binding to MT1 MMP rather than at an independent membrane site. Together, the data suggest that TIMP2 forms a receptor with MT1 MMP that regulates the concentration and efficient generation of functionally active gelatinase A.

Animals↗
PubMed1998

Protecting the world's children: the story of WHO's immunization programme.

Systematic immunization on a worldwide scale was not officially recognized as a practical possibility until 1974, when WHO launched its Expanded Programme on Immunization. Today, 80% of the world's children receive this form of protection against childhood diseases during their first year of life. Coverage can reach 90% by the year 2000, the effectiveness of the vaccines used is improving, and vaccines against additional diseases are being added to the programme.

Communicable Disease Control↗
PubMed1998

Climbing higher.

A New York hospital builds a more equitable clinical ladder system to include nurse managers, clinical nurse specialists, nurse practitioners, and nurse-midwives. The system defines the nurses' roles and specific performance criteria.

Career Mobility↗
PubMed1997

Kallikreins and kinins in inflammatory-like events in the reproductive tract.

The normal reproductive events of proliferation of the endometrial lining of the uterus during the menstrual cycle and ovulation have been likened to inflammatory-like events. The kallikrein-kinin system is involved in inflammatory processes in many tissues. In this review, we identify which components of the kallikrein-kinin system--the enzyme, tissue kallikrein; the substrate, low molecular weight kininogen and the effector receptor for the generated bradykinin peptide, the B2 receptor--have been identified in the uterus and ovary and their known involvement in the function of these organs. All three components have been localized to the glandular epithelial cells of the human endometrium. Tissue kallikrein gene expression is elevated midcycle when estrogens levels are also rising. This is also a time of extensive endometrial proliferation and tissue remodelling in preparation for embryo implantation, an event which is likened to other inflammatory processes. Similarly, tissue kallikrein gene expression was elevated following the estrogen surge at proestrous in the rat uterus, suggesting tissue kallikrein gene expression may be regulated by estrogens. Tissue kallikrein enzyme activity and gene expression has been demonstrated in the rat ovary and shown to be variously altered at the time of ovulation. Bradykinin has also been implicated in the expulsion of the ovum at the time of ovulation. These findings show that various components of the kallikrein-kinin system are present in the uterus and ovary. Further studies are required to more fully delineate their role in reproductive function.

Animals↗
PubMed1997

Tissue kallikrein and the bradykinin B2 receptor are expressed in endometrial and prostate cancers.

KLK1/tissue kallikrein is a member of a family of structurally related serine proteases which exhibit a diverse range of enzymic activities. Other members of this family of genes and the bradykinin (B2) receptor have been implicated in cancer processes. The KLK genes are expressed in various organs of the reproductive tract, including the prostate and uterus. In this study, we have examined whether KLK1/tissue kallikrein and the B2 receptor were both expressed in cancers emanating from these organs. We have shown that KLK1/tissue kallikrein and the B2 receptor are expressed, to varying degrees, in prostate disease and 2 human prostate cancer cell-lines, LNCaP and DU145. KLK1 is also expressed in a range of endometrial cancers, although at lower levels than that observed for normal human endometrial tissues. These findings suggest that a functional kallikrein-kinin system is present in prostate disease, in particular, which may be important in the process of tumorigenesis in this tissue.

Blotting, Southern↗
PubMed1997

The impact of immunization control activities on measles outbreaks in middle and low income countries.

BACKGROUND: The World Health Organization recommended strategy for responding to measles outbreaks in developing countries does not promote the use of immunization campaigns due to their high cost, disruptive nature and limited impact. Given the substantial morbidity and mortality associated with such outbreaks, a literature review was conducted as a basis for re-evaluating this policy. METHODS: Reports of supplementary immunization activities that were performed to control measles outbreaks in middle or low income countries were identified. The impact of the immunization activities on the course of each outbreak was evaluated by examining the data provided. RESULTS: Of 66 reports detailing a measles outbreak in a middle or low income country, 17 described supplementary immunization activities which included seven 'non-selective' immunization campaigns, three 'selective' campaigns and one use of an early 2-dose schedule. Eight of the reports commented on the impact of the response, five of which reported a reduction in outbreak morbidity. Only one of the reports, from an isolated island outbreak, provided sufficient data to support a possible reduction in outbreak-associated morbidity. CONCLUSIONS: There are limited data on the impact of measles outbreak immunization activities from developing countries. The available data do not support a change in the WHO recommended strategy for conducting a limited, if any, immunization response to such outbreaks. Immunization strategies which aim to prevent outbreaks may be more effective than campaigns to interrupt transmission of an outbreak which has already begun.

Child↗
PubMed1997

Amino acid residues required for binding of vascular cell adhesion molecule-1 to integrin alpha 4 beta 7.

The homologous Ig-like domains 1 and 4 of vascular cell adhesion molecule (VCAM)-1 present binding sites to the leukocyte integrins alpha 4 beta 1 and alpha 4 beta 7 . In the present study, amino acid substitution mutants were used to identify sequence motifs mediating binding of integrin alpha 4 beta 7 to the first domain of VCAM-1. We demonstrate that binding of integrin alpha 4 beta 7 to VCAM-1 containing the D40A mutation located in the loop between beta strands C1 and D1 was completely abrogated and was not restored by activating integrin binding functions with Mn2+. Thus, the I(39)DSP motif functions as a central recognition site for integrin alpha 4 beta 7. Analysis of the E66A mutation demonstrated that the G(64)NEH sequence, which is exposed on the loop structure between beta strands E1 and F1, represents an additional recognition site for alpha 4 beta 7 integrin. However, the inhibitory effect of the E66A mutation on cell binding was not specific for alpha 4 beta 7 but was also observed for integrin alpha 4 beta 1. In contrast to the I(39)DSP and G(64)NEH sequences, the K(79)LEK motif present in beta strand G1 was involved in binding to alpha 4 beta 1 but not alpha 4 beta 7. The function of G(64)NEH and K(79)LEK motifs in alpha 4++-integrin interactions was confirmed by divalent cation titration assays and peptide inhibition studies. Integrin binding to E66A or E81A;K82A mutants was restored by activation with saturating concentrations of Mn2+. Binding of both alpha 4 beta 1 and alpha 4 beta 7 integrins was not affected by E29A, R36A, E50A or E87A mutations. Together, these results identify the I(39)DSP and G(64)NEH motifs as common recognition sites for both alpha 4 beta 1 and alpha 4 beta 7 integrins, whereas the K(79)LEK sequence appears to confer specificity for alpha 4 beta 1 binding.

Amino Acid Sequence↗
PubMed1997

Subacute bacterial endocarditis masquerading as type III essential mixed cryoglobulinemia.

An adult man presented severely ill with vasculitis of his lower extremities and with impaired kidney function. After detailed evaluation at a local hospital, a diagnosis of essential type III cryoglobulinemia was made. High-dose steroid and cyclophosphamide therapy was begun. The patient improved dramatically. However, 6 wk later when his steroid dose was reduced to 30 mg daily, vasculitis recurred. Intensifying his immunosuppressive therapy only worsened his condition. He was than transferred to the Ohio State University Medical Center for consideration for plasmapheresis for the presumed essential type III cryoglobulinemia. However, our evaluation showed that he had bacterial endocarditis causing his type III cryoglobulinemia. When immunosuppressive drugs were stopped and antibiotics were begun, his condition resolved completely. This case illustrates the difficulty of identifying infectious causes of cryoglobulinemia and emphasizes that an initial, highly favorable response of vasculitis to immunosuppressive therapy does not exclude an infectious cause for the vasculitis.

Acute Kidney Injury↗
PubMed1997

A prostate-specific antigen-like protein associated with renal cell carcinoma in women.

Renal cell carcinoma (RCC) is the most common form of cancer affecting the kidney. There is currently no biochemical marker for this disease. We have shown that serum-immunoreactive prostate-specific antigen (PSA) levels, as measured by the two-site Ciba-Corning ACS:180 immunochemiluminometric assay, are elevated in women with RCC. Although the levels were low (0.13-0.89 microgram/l), serum PSA was clearly measurable prior to surgery in 13 of 17 women (76%) with RCC. Significantly, the PSA levels fell to undetectable after nephrectomy. Seventeen normal women also had undetectable (<0. 1 microgram/l) PSA levels. Two women, who had several serum PSA measurements performed postoperatively, showed a t(1/2) of 2-3 days equivalent to that observed for PSA in men following radical prostatectomy for prostate cancer. The 17 RCCs evaluated in this study consisted of 10 stage A, 4 stage B, and 3 stage C tumors. There was no relationship between tumor size, stage, or serum-immunoreactive PSA level, although the majority of these tumors are low grade. We have shown by reverse transcription-PCR, using PCR primers directed to the NH2 terminal coding region of the KLK3 (PSA) gene and the closely related KLK1 and KLK2 genes, that these genes are not expressed in these tumors. Our findings show, however, that elevated levels of a circulating PSA-like protein are present in women with RCC.

Adult↗