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Biomedical subjects

J Chao

Publications and source records attributed to J Chao.

At least 73 records · Page 4Linked to original sources
PubMed1998

Cellular localization of kallistatin and tissue kallikrein in human pancreas and salivary glands.

The tissue kallikrein-kinin system contributes to the regulation of local blood flow, vascular permeability, inflammatory responses, and ion transport. Tissue kallikrein is a serine proteinase which produces vasoactive kinin peptides. Kallistatin specifically binds to tissue kallikrein and inhibits its proteolytic activity. To investigate their anatomical relationship in the human pancreas and salivary glands, the expression and localization of kallistatin and tissue kallikrein were identified by immunoassays, immunohistochemistry, and in situ hybridization histochemistry. Human kallistatin and tissue kallikrein levels were measured by ELISA and radioimmunoassay, respectively, in pancreatic and salivary tissue extracts, and in pancreatic fluid and saliva. Immunoreactive kallistatin and kallikrein were colocalized in acinar cells of the human pancreas by immunohistochemistry. In situ hybridization histochemistry confirmed the presence of both mRNAs in pancreatic acini. In salivary glands, kallistatin and kallikrein mRNAs were also colocalized in serous acinar cells, and the kallikrein transcript was further localized to striated and interlobular ducts. Immunoreactive kallistatin was localized in serous acinar and demilune cells of salivary glands and kallikrein was localized to the epithelium of striated and interlobular ducts. The colocalization and/or coexpression of human tissue kallikrein and kallistatin in the pancreas and salivary glands suggest a role for kallistatin in the regulation of tissue kallikrein in these organs.

Carrier Proteins↗
PubMed1998

Adenovirus-mediated kallikrein gene delivery reverses salt-induced renal injury in Dahl salt-sensitive rats.

BACKGROUND: The tissue kallikrein-kinin system has been shown to play a role in cardiac and renal functions. In this study, we investigated the ability of kallikrein gene delivery to reverse salt-induced cardiac hypertrophy and renal injury in Dahl salt-sensitive rats. METHODS: Adenovirus harboring the human tissue kallikrein gene, Ad.CMV-cHK, was delivered intravenously into Dahl salt-sensitive rats suffering from hypertension, cardiac hypertrophy and renal damage induced by a high salt diet (4% NaCl) for four weeks. RESULTS: Expression of human kallikrein mRNA was detected in rat kidney, heart, aorta and liver, and immunoreactive human kallikrein levels were measured in the serum and urine of rats receiving gene delivery. A single injection of Ad.CMV-cHK caused a significant reduction of blood pressure for more than two weeks. Kallikrein gene transfer caused left ventricular mass reduction and elevated glomerular filtration rate, renal blood flow, urinary excretion, urinary kinin, nitrite/nitrate content, cGMP and cAMP levels. Morphological investigations showed that kallikrein gene transfer caused a significant reversal in salt-induced tissue and organ damage. In the heart, cardiac hypertrophy and fibrosis were reduced, and in the kidney, both glomerular sclerotic lesions and tubular damage were reversed. CONCLUSIONS: Adenovirus-mediated kallikrein gene delivery is effective in reversing salt-induced cardiac hypertrophy and renal injury in Dahl-salt sensitive rats.

Adenoviridae↗
PubMed1998

Human kallikrein gene delivery protects against gentamycin-induced nephrotoxicity in rats.

The tissue kallikrein-kinin system has been shown to play important roles in cardiovascular and renal function. The aim of this study was to investigate potential protective effects of kallikrein gene delivery in gentamycin-induced nephrotoxicity. Rats were injected subcutaneously with gentamycin daily for 10 to 14 days. Adenovirus, Ad.CMV-cHK carrying the human tissue kallikrein gene or Ad.CMV-LacZ carrying the beta-galactosidase gene under the control of the cytomegalovirus promoter, were delivered intravenously on the first day of gentamycin administration. The expression of human tissue kallikrein mRNA was identified in the kidney, aorta, heart and liver and immunoreactive human kallikrein levels were measured in the serum and urine of rats receiving kallikrein gene delivery. Adenovirus-mediated kallikrein gene delivery significantly increased the renal blood flow, glomerular filtration rates, and urine flow while it attenuated renal tubular damage, cellular necrosis, lumenal protein casts and reduced ventricular weight and cardiomyocyte size. Kallikrein gene delivery caused a decrease in blood urea nitrogen levels and increases in urinary kinin and nitrite/nitrate levels. This study shows that kallikrein gene delivery exhibits protection against gentamycin-induced nephrotoxicity, and raises the potential for kallikrein gene therapy to treat drug-induced renal diseases.

Adenoviridae↗
PubMed1998

Localization and secretion of tissue kallikrein in peptidoglycan-induced enterocolitis in Lewis rats.

The plasma kallikrein-kinin system is a mediator of intestinal inflammation induced by peptidoglycan-polysaccharide from group A streptococci (PG-APS) in rats. In this study we investigated the participation of intestinal tissue kallikrein (ITK). Lewis rats were injected intramurally with PG-APS. ITK was visualized by immunohistochemical staining. Cecal ITK concentration was measured by radioimmunoassay, and gene expression was evaluated by RNase protection assay. Kallikrein-binding protein (KBP) was evaluated in plasma by ELISA. Tissue kallikrein was identified in cecal goblet cells in both control and PG-APS-injected rats and in macrophages forming granulomas in inflamed tissues. Cecal ITK was significantly lower in acute and chronic phases of inflammation and in supernatant from in vitro cultures of inflamed cecum. ITK mRNA levels were not significantly different. Plasma KBP levels were significantly reduced in inflamed rats. The presence of tissue kallikrein in macrophages suggests participation in experimental colitis. The decrease of ITK in the inflamed intestine associated with unchanged mRNA levels suggests ITK release during intestinal inflammation.

Animals↗
PubMed1998

Kallikrein gene delivery attenuates hypertension and cardiac hypertrophy and enhances renal function in Goldblatt hypertensive rats.

To demonstrate potential therapeutic effects of kallikrein gene delivery, we delivered adenovirus (Ad.CMV-cHK) carrying the human tissue kallikrein gene into two-kidney, one-clip Goldblatt hypertensive rats. A single intravenous injection of the recombinant adenovirus caused a delay of blood pressure increase that began 1 day after injection and continued for 24 days. A maximal blood pressure reduction was observed in rats receiving kallikrein gene delivery compared with control rats receiving Ad.CMV-LacZ (160+/-5 versus 186+/-7 mm Hg, n=6, P<.01). The expression of human tissue kallikrein mRNA was identified in the kidney, heart, aorta, and liver of rats receiving kallikrein gene delivery. Immunoreactive human kallikrein levels were measured in rat serum and urine in a time-dependent manner. Adenovirus-mediated kallikrein gene delivery caused a significant reduction in the left ventricular mass and cardiomyocyte size, as well as an increase in renal blood flow, urine flow, glomerular filtration rates, electrolyte output, and urine excretion. Enhanced renal responses were accompanied by significant increases in urinary kinin, nitrite/nitrate, and cyclic GMP levels. These findings show that the expression of human tissue kallikrein via gene delivery has protective effects against renovascular hypertension and cardiovascular and renal dysfunction.

Adenoviridae↗
PubMed1998

Illuminating the 'black box'. A description of 4454 patient visits to 138 family physicians.

BACKGROUND: The content and context of family practice outpatient visits have never been fully described, leaving many aspects of family practice in a "black box," unseen by policymakers and understood only in isolation. This article describes community family practices, physicians, patients, and outpatient visits. METHODS: Practicing family physicians in northeast Ohio were invited to participate in a multimethod study of the content of primary care practice. Research nurses directly observed consecutive patient visits, and collected additional data using medical record reviews, patient and physician questionnaires, billing data, practice environment checklists, and ethnographic fieldnotes. RESULTS: Visits by 4454 patients seeing 138 physicians in 84 practices were observed. Outpatient visits to family physicians encompassed a wide variety of patients, problems, and levels of complexity. The average patient paid 4.3 visits to the practice within the past year. The mean visit duration was 10 minutes. Fifty-eight percent of visits were for acute illness, 24% for chronic illness, and 12% for well care. The most common uses of time were history-taking, planning treatment, physical examination, health education, feedback, family information, chatting, structuring the interaction, and patient questions. CONCLUSIONS: Family practice and patient visits are complex, with competing demands and opportunities to address a wide range of problems of individuals and families over time and at various stages of health and illness. Multimethod research in practice settings can identify ways to enhance the competing opportunities of family practice to improve the health of their patients.

Adult↗
PubMed1998

Billing for physician services: a comparison of actual billing with CPT codes assigned by direct observation.

BACKGROUND: Little is known about the accuracy of family physicians' use of the Current procedural Terminology (CPT) coding scheme for office visits, despite increased administrative oversight of Medicare billing practices. In addition, the patient and visit characteristics that are associated with over- and undercoding are not well understood. METHODS: This study compared coding for evaluation and management (E&M) services billed for 3791 visits to 138 family physicians with the codes assigned by trained research nurses using direct observation. We calculated the degree to which the codes for E&M were concordant with the observer-assigned codes. Analysis of variance and logistic regression were used to examine the association of visit and patient characteristics with discordance between billed and observer-assigned CPT codes. RESULTS: Billing codes were concordant for 55% of encounters. Discordance was evenly distributed between under- and overcoding. Concordance of billed and observed codes was greatest for patients with indemnity insurance. Undercoding increased with longer visit length and a smaller percentage of the visit spent planning treatment. Overcoding was more common during visits with a greater percentage of time spent chatting, planning treatment, and delivering preventive services. CONCLUSIONS: Family physicians are generally accurate in their billing procedures. The findings on patient and visit characteristics associated with over- or undercoding may be used by practicing clinicians to enhance the accuracy of their coding and billing procedures.

Adult↗
PubMed1997

Gene therapy in hypertension: adenovirus-mediated kallikrein gene delivery in hypertensive rats.

Tissue kallikrein has been shown to play a role in blood pressure regulation, and abnormalities in the kallikreinkinin system are considered to be a factor in the pathogenesis of hypertension. To elucidate the potential therapeutic effects of kallikrein gene delivery in hypertension, an adenoviral vector containing the human tissue kallikrein gene under the control of a cytomegalovirus promoter, Ad.CMV-cHK, was intravenously injected into spontaneously hypertensive rats (SHR). A single injection of Ad.CMV-cHK into SHR caused a sustained delay in the increase in blood pressure from day 2 to day 41 post injection, as compared to control rats receiving Ad.CMV-LacZ adenovirus. Adenovirus-mediated kallikrein gene delivery had no effect on the blood pressure of normotensive Wistar-Kyoto rats. Human tissue kallikrein mRNA was detected in the liver, kidney, spleen, adrenal gland, and aorta. Immunoreactive human tissue kallikrein can be detected in sera and urine of rats receiving kallikrein gene delivery. Human tissue kallikrein in rat serum was at the highest level 5 days post injection, and the level declined gradually. Urinary kinin and cGMP levels were significantly increased in rats receiving kallikrein gene delivery compared to Ad.CMV-LacZ control rats. These results show that adenovirus-mediated delivery of human tissue kallikrein results in high-efficiency expression and blood pressure reduction in SHR. Application of adenovirus-mediated systemic expression of the tissue kallikrein gene may provide a unique way of delivering the gene product into the vasculature and could have important therapeutic implications in treating hypertension.

Adenoviridae↗
PubMed1997

Molecular cloning and expression of rat kallistatin gene.

We have previously purified and cloned human kallistatin and rat kallikrein-binding protein (RKBP), which are tissue kallikrein inhibitors belonging to the serine proteinase inhibitor superfamily. In this study, we have cloned and sequenced the gene encoding rat kallistatin with Phe-Phe-Ser-Ala-Gln at positions P2-P3', which is identical to the reactive center of human kallistatin. Rat kallistatin is highly similar to human kallistatin, sharing 68% and 57% sequence identity at the cDNA and the amino acid levels. The rat kallistatin gene exists in a single copy and is located on chromosome 6. An SphI RFLP is found between SHR and WKY rats at or near the rat kallistatin gene locus. Two amino acid polymorphisms of the rat kallistatin gene between these two strains were found by sequence analysis. A candidate promoter in the 5'-flanking region (109 bp) of the rat kallistatin gene has been identified by reporter assays. The expression of rat kallistatin in the liver is growth-dependent and down-regulated during acute phase inflammation. Recombinant rat kallistatin produced in E. coli is able to bind to tissue kallikrein, and the interaction is inhibited by heparin. These characteristics define rat kallistatin as the counterpart of human kallistatin.

Amino Acid Sequence↗
PubMed1997

Tissue-specific expression and promoter analyses of the human tissue kallikrein gene in transgenic mice.

The expression of the tissue kallikrein gene is tissue-specific and exhibits a complex pattern of transcriptional and post-translational regulation. Information concerning the mechanism of its tissue-specific expression has been limited owing to the lack of suitable cell lines for the expression study. We approached this problem by introducing human tissue kallikrein gene constructs into mouse embryos, creating transgenic lines carrying its coding sequence with varying lengths of the promoter region. One construct (PHK) contained 801 bp in the 5'-flanking region and two deletion constructs contained either 302 bp (D300) or 202 bp (D200) of the promoter region. The expression of human tissue kallikrein in these transgenic mice was monitored by Northern blot, reverse transcriptase-PCR followed by Southern blot, and radioimmunoassay. In all three lines, human tissue kallikrein was expressed predominantly in the pancreas and at lower levels in other tissues, including salivary gland, kidney and spleen. This pattern was similar to that of tissue kallikrein expression in human tissues. The D300 line has higher levels of transgene expression than the D200 and PHK lines. The results indicate that the 202 bp segment immediately upstream of the translation starting site is sufficient to direct a tissue-specific expression pattern of the human tissue kallikrein gene, and that regulatory elements might exist between -801 and -202.

Animals↗
PubMed1997

Kallistatin is a potent new vasodilator.

Kallistatin is a serine proteinase inhibitor which binds to tissue kallikrein and inhibits its activity. The aim of this study is to evaluate if kallistatin has a direct effect on the vasculature and on blood pressure homeostasis. We found that an intravenous bolus injection of human kallistatin caused a rapid, potent, and transient reduction of mean arterial blood pressure in anesthetized rats. Infusion of purified kallistatin (0.07-1.42 nmol/kg) into cannulated rat jugular vein produced a 20-85 mmHg reduction of blood pressure in a dose-dependent manner. Hoe 140, a bradykinin B2-receptor antagonist, had no effect on the hypotensive effect of kallistatin yet it abolished the blood pressure-lowering effect of kinin and kallikrein. Relaxation of isolated aortic rings by kallistatin was observed in the presence (ED50 of 3.4 x 10(-9) M) and in the absence of endothelium (ED50 of 10(-9) M). Rat kallikrein-binding protein, but not kinin or kallikrein, induced vascular relaxation of aortic rings. Neither Hoe 140 nor Nomega-nitro--arginine methyl ester, a nitric oxide synthase inhibitor, affected vasorelaxation induced by kallistatin. Kallistatin also caused dose-dependent vasodilation of the renal vasculature in the isolated, perfused rat kidney. Specific kallistatin-binding sites were identified in rat aorta by Scatchard plot analysis with a Kd of 0.25+/-0.07 nM and maximal binding capacity of 47.9+/-10.4 fmol/mg protein (mean+/-SEM, n = 3). These results indicate that kallistatin is a potent vasodilator which may function directly through a vascular smooth muscle mechanism independent of an endothelial bradykinin receptor. This study introduces the potential significance of kallistatin in directly regulating blood pressure to reduce hypertension.

Adrenergic beta-Antagonists↗
PubMed1997

Expression and localization of human kallistatin in rat submandibular gland after intracapsular gene injection.

Gene delivery into rat submandibular gland in vivo by direct intracapsular injection has been studied. After the administration of adenovirus constructs, Ad-RSV-LacZ and Ad-CMV-LacZ, beta-galactosidase expression was localized in the granular convoluted tubular and striated duct cells of rat submandibular gland by in situ enzyme histochemistry. Adenovirus-mediated delivery of the human kallistatin gene (Ad-RSV-HKBP) into rat submandibular gland results in the expression of human kallistatin in a time-dependent manner. The expression of immunoreactive kallistatin in submandibular gland was detected 1 day after the Ad-RSV-HKBP injection and it reached a plateau (1-2 ng/mg protein) 2 days after gene delivery. Higher levels of human kallistatin were found in the submandibular gland of 6-month-old rats than in one-month-old rats. After direct gene injection, human kallistatin was localized mainly in cells of the granular convoluted tubules and striated ducts of rat submandibular gland using a specific monoclonal antibody to human kallistatin. The results indicate that direct intracapsular gene delivery into the submandibular gland provides a simple and reliable method for introducing foreign genes into the gland. This method can be used for studying gene regulation in vivo and may have potential for gene therapy in oral diseases.

Animals↗
PubMed1997

Adenovirus-mediated delivery of human kallistatin gene reduces blood pressure of spontaneously hypertensive rats.

Human kallistatin, or human tissue kallikrein-binding protein (HKBP), is a serine proteinase inhibitor (serpin). Transgenic mice overexpressing rat kallikrein-binding protein are hypotensive. To elucidate therapeutic potentials of kallistatin in hypertension, the human kallistatin gene in an adenoviral vector was directly introduced into spontaneously hypertensive rats (SHR) through portal vein injection. The kallistatin cDNA construct (RSV-cHKBP) under the promoter control of Rous sarcoma virus 3' long terminal repeat (LTR) was incorporated into adenovirus (Ad.RSV-cHKBP). Recombinant kallistatin in 293 cells transfected with RSV-cHKBP or Ad.RSV-cHKBP was measured by ELISA and by its complex formation with tissue kallikrein. A single intraportal vein injection of Ad.RSV-cHKBP at a dose of 8 x 10(10) pfu results in a significant reduction of blood pressure of SHR for 4 weeks. Human kallistatin mRNA was detected in the liver, spleen, kidney, aorta, and lung of rats receiving gene delivery. Immunoreactive human kallistatin in rat serum was detected at the highest level 1 day post injection and at lesser amounts in rat tissues. This study shows that adenovirus harboring Ad.RSV-cHKBP produces functional kallistatin, and adenovirus-mediated transfer of the human kallistatin gene reduces blood pressures of SHR. The results suggest that kallistatin may function as a vasodilator in vivo and provide important information for a potential gene therapy approach to hypertension.

Adenoviridae↗
PubMed1997

Experimental kallikrein gene therapy in hypertension, cardiovascular and renal diseases.

Hypertension is a multi-gene and multi-factorial disorder affecting about 25% of the population. Hypertensive subjects are more likely to develop other cardiovascular diseases such as peripheral vascular disease, coronary heart disease, congestive heart failure and cerebrovascular disease. To demonstrate potential therapeutic effects of somatic gene delivery in treating hypertension, we delivered human tissue kallikrein in the form of naked DNA or in an adenovirus vector into hypertensive rats. Naked DNA constructs were delivered into spontaneously hypertensive rats via intramuscular, intravenous, intraportal vein and intraperitoneal routes. A single injection of human kallikrein DNA construct caused a sustained reduction of blood pressure which began 1 week post-injection and continued for more than 6 weeks. The hypotensive effect caused by somatic gene delivery of human tissue kallikrein in hypertensive rats is reversed by aprotinin, a potent tissue kallikrein inhibitor. Both systemic and local delivery of the human tissue kallikrein gene in an adenovirus vector were found to be highly effective in producing a rapid and sustained reduction of blood pressure in hypertensive rat models such as spontaneously hypertensive rats; two kidney, one clip Goldblatt hypertensive rats; and Dahl salt-sensitive rats. The expression of human tissue kallikrein in rats was identified in the heart, kidney, aorta, lung and liver by reverse transcription-polymerase chain reaction followed by Southern blot analysis and by ELISA. Adenovirus-mediated kallikrein gene delivery also resulted in the attenuation of glomerular and tubular damage and reduction of the left ventricular mass and cardiomyocyte size in Dahl salt-sensitive rats fed a high salt diet. The ability of kallikrein gene delivery to produce a wide spectrum of beneficial effects makes it an excellent candidate in treating salt-related hypertension as well as cardiovascular and renal diseases. These results suggest the feasibility of applying somatic gene therapy for treating hypertension and salt-related cardiovascular and renal disorders.

Adenoviridae↗
PubMed1997

DNA polymorphisms in the 5'-flanking region of the human tissue kallikrein gene.

Human tissue kallikrein gene polymorphisms were identified in the promoter region by polymerase chain reaction (PCR) and DNA sequencing. One polymorphic region was identified between nucleotides -121 and -133 with respect to the transcription initiation site of the tissue kallikrein gene. Ten alleles with length and nucleotide sequence variations were detected among 108 unrelated Caucasians, African-Americans, and Asians. The polymorphisms show Hardy-Weinberg equilibrium. Allele-specific amplification and PCR analyses were used to detect the various forms of polymorphism. The promoter activity was analyzed in human embryonic kidney 293 cells by transient transfection assays. Sequential 5'-deletion analysis of the tissue kallikrein gene promoter revealed that the region from -144 to -98 is crucial for its promotor activity, while alleles D and H had significantly lower promoter activities than the other alleles in the -940/+10 deletion constructs. The high variability and the proximity to the tissue kallikrein gene render it suitable for application as a new tool in genetic studies for evaluation of the tissue kallikrein gene in the pathogenesis of human essential hypertension.

Alleles↗
PubMed1997

Beneficial effects of kallikrein-binding protein in transgenic mice during endotoxic shock.

Rat kallikrein-binding protein (RKBP) is a negative acute phase protein. The potential role of RKBP in inflammation was evaluated in transgenic mice overexpressing the RKBP gene under the control of the mouse metallothionein metal-responsive promoter. Bacterial endotoxic lipopolysaccharide (LPS) was injected intraperitoneally into mice at a dose of 600 microg/25 g body weight. The death toll was recorded every 12 hours for 3 days. The survival rate of transgenic male mice (n=78) was 33.3% while that of control male mice (n=54) was 9.3% 3 days post LPS injection. In comparison, the survival rate of transgenic female mice (n=59) was 55.9% while that of control female mice (n=65) was 30.8%. Recombinant RKBP levels in the circulation of these mice increased by 3-fold after LPS treatment. The results show that RKBP transgenic mice have a higher survival rate than their non-transgenic control littermates after endotoxin shock and female mice are more resistant to lethality induced by endotoxin shock than male mice in both transgenic and control groups. These findings suggest that kallikrein-binding protein has a protective effect during acute phase inflammation.

Animals↗