Reactive-site specificity of human kallistatin toward tissue kallikrein probed by site-directed mutagenesis

Kallistatin is a serine proteinase inhibitor that forms complexes with tissue kallikrein and inhibits its activity. In this study, we compared the inhibitory activity of recombinant human kallistatin and two mutants, Phe388Arg (P1) and Phe387Gly (P2), toward human tissue kallikrein. Recombinant kallistatins were expressed in Escherichia coli and purified to apparent homogeneity using metal-affinity and heparin-affinity chromatography. The complexes formed between recombinant kallistatins and tissue kallikrein were stable for at least 150 h. Wild-type kallistatin as well as both Phe388Arg and Phe387Gly mutants act as inhibitors and substrates to tissue kallikrein as analyzed by complex formation. Kinetic analyses showed that the inhibitory activity of Phe388Arg variant toward tissue kallikrein is two-fold higher than that of wild type (P1Phe), whereas Phe387Gly had only 7% of the inhibitory activity toward tissue kallikrein as compared to wild type. The Phe388Arg variant but not wild type inhibited plasma kallikrein's activity. These results indicate that P1Arg variant exhibits more potent inhibitory activity toward tissue kallikrein while wild type (P1Phe) is a more selective inhibitor of tissue kallikrein. The P2 phenylalanine is essential for retaining the hydrophobic environment for the interaction of kallistatin and kallikrein.

Adenovirus-mediated human tissue kallikrein gene delivery inhibits neointima formation induced by interruption of blood flow in mice

Tissue kallikrein cleaves kininogen to produce vasoactive kinin peptides. Binding of kinins to bradykinin B(2) receptors on vascular endothelial cells stimulates the release of nitric oxide and prostacyclin, thus activating the cGMP and cAMP pathways. In this study, we evaluated the effects of adenovirus-mediated human tissue kallikrein gene (Ad.CMV-cHK) delivery in a mouse model of arterial remodeling induced by permanent alteration in shear stress conditions. Mice underwent ligature of the left common carotid artery and were injected intravenously with saline or 1.8 x 10(9) plaque-forming units of Ad.CMV-cHK or control virus (Ad.CMV-LacZ). Fourteen days after surgery, morphometric analysis revealed that Ad. CMV-cHK reduced neointima formation by 52% (P<0.05) compared with Ad. CMV-LacZ. Expression of human tissue kallikrein (HK) mRNA was detected in mouse carotid artery, aorta, kidney, heart, and liver, and recombinant HK was present in the urine and plasma of mice receiving HK gene. Kallikrein gene transfer resulted in increases in urinary kinin, cGMP, and cAMP levels. The protective action of Ad. CMV-cHK on neointima formation was significantly reduced (P<0.05) in mice with knockout of the kinin B(2) receptor gene compared with wild-type control mice (J129Sv mice). In contrast, the effect of Ad. CMV-cHK was amplified (P<0.05) in transgenic mice overexpressing human B(2) receptor compared with wild-type control mice (c57/Bl6 mice). Thus, the inhibitory effect of recombinant kallikrein on structural alterations caused by the interruption of blood flow appears to be mediated by the B(2) receptor. These results provide new insight into the role of the tissue kallikrein-kinin system in vascular remodeling and suggest the application of HK gene therapy to treat restenosis and atherosclerosis.

Kallistatin stimulates vascular smooth muscle cell proliferation and migration in vitro and neointima formation in balloon-injured rat artery

Kallistatin, a serine proteinase inhibitor (serpin), is expressed in the endothelial and smooth muscle cells of blood vessels. The potential function of kallistatin in vascular biology was investigated by studying its role in the proliferation and migration of cultured primary aortic vascular smooth muscle cells (VSMCs) in vitro and in neointima formation in rat artery after balloon angioplasty in vivo. Exogenous kallistatin induced a >2-fold increase of VSMC proliferation and cell growth as measured by [(3)H]thymidine incorporation and cell counts and a 2.3-fold increase of cell migration in modified Boyden chambers. In balloon-injured vessels, endogenous kallistatin mRNA and protein levels increased up to 10-fold as determined by competitive polymerase chain reaction and by ELISA. Intense staining of kallistatin mRNA was identified in the proliferating VSMCs of balloon-injured arteries during cell migration from media to neointima by in situ hybridization histochemistry and immunohistochemistry. We observed an induction of kallistatin expression by platelet-derived growth factor (PDGF) and upregulation of p42/44 mitogen-activated protein kinase (MAPK) activity by kallistatin in cultured VSMCs. Conversely, adenovirus-mediated transfer of kallistatin antisense cDNA into cultured VSMCs inhibited PDGF-induced p42/44 MAPK activity and cell proliferation. Furthermore, local delivery of adenovirus carrying kallistatin antisense cDNA significantly downregulated kallistatin mRNA levels and attenuated neointima formation in balloon-injured rat arteries in vivo. These results indicate that kallistatin may play an important role in mediating PDGF-induced MAPK pathway on VSMC proliferation and in neointima formation after balloon angioplasty.

Enhanced renal function in bradykinin B(2) receptor transgenic mice

The tissue kallikrein-kinin system has been recognized as a paracrine and/or autocrine hormonal system that regulates arterial pressure, renal hemodynamics, and electrolyte excretion. We have created a transgenic mouse model overexpressing human bradykinin B(2) receptor, and the mice developed lifetime hypotension. With this animal model, we further analyzed the potential role of B(2) receptors in regulation of renal function. Baseline urinary excretion, urinary potassium excretion, and pH were significantly increased in transgenic mice, whereas urinary sodium excretion and serum sodium concentration were unaltered. Transgenic mice exhibited increased renal blood flow, glomerular filtration rate, and urine flow. Enhanced renal function was accompanied by significant increases in urinary nitrate/nitrite, cGMP, and cAMP levels with unaltered urinary kinin levels in transgenic mice compared with control siblings. Renal cGMP and cAMP content was also significantly increased in transgenic mice. Because the renin-angiotensin system exerts vasoconstriction buffering vasodilation of the kallikrein-kinin system, expression of renin-angiotensin components was examined by Northern blot analysis. We found a significant increase in hepatic angiotensinogen expression with no changes in renal renin and pulmonary angiotensin-converting enzyme mRNA levels in B(2) receptor transgenic mice. These studies showed that overexpression of B(2) receptors in transgenic mice resulted in hypotension and enhanced renal function through activation of nitric oxide-cGMP and cAMP signal transduction pathways.

Diffuse annular fusiform adenocarcinoma in a dog

Canine colonic intestinal adenocarcinoma typically presents as rectal polypoid or annular stenotic masses causing clinical signs consistent with large bowel disease. This report discusses an unusual case of intestinal adenocarcinoma in an 11-year-old, neutered male German shepherd dog presented for evaluation of anorexia, profuse watery diarrhea, and weight loss. In this dog, colonic adenocarcinoma diffusely infiltrated the entire large bowel and caused an annular fusiform lesion, as confirmed by endoscopic biopsies and postmortem examination. Other unique features included a paucity of desmoplasia associated with the neoplastic lesion and widespread metastasis to regional lymph nodes, lung, and prostate.

Effect of substrate roughness on the corrosion behaviour of the Al2O3/MA 956 system

This paper presents the influence of substrate roughness on the corrosion behaviour of the Al2O3/MA 956 system. An alumina layer of thickness 1-5 microm was generated of the MA956 alloy by thermal oxidation at 1100 degrees C using different exposure times. This Al2O3/MA 956 system with a polished substrate has shown excellent corrosion behaviour in a physiological fluid, due to the fact that the alpha-Al2O3 layer formed is dense, continuous and firmly adhered to the substrate, irrespective of the scale thickness. This good adherence allows it to withstand potentials above 1.7 V. Specimens with rough finish substrate and treatment times above 10 h present spallation of the alumina layer at the crests of the roughness profile. In this case a mixed corrosion behaviour between an alumina coated material and one with a passive layer is observed. In both types of specimens, rough and smooth, once the passivation layer is broken the repassivation capacity of the substrate is ensured due to the high chromium content of the alloy, under oxygenation conditions.

Kallikrein gene delivery attenuates myocardial infarction and apoptosis after myocardial ischemia and reperfusion

The tissue kallikrein-kinin system is present in the heart, and kinin has been shown to have cardioprotective effects. In this study, we investigated the potential role of tissue kallikrein in myocardial ischemia/reperfusion injury through adenovirus-mediated human kallikrein gene delivery. One week after gene delivery, the rats were subjected to a 30-minute coronary occlusion followed by a 2-hour reperfusion. Kallikrein gene delivery caused significant decreases in the ratio of infarct size to ischemic area at risk (from 69.6% to 44.5%, n=10 and 8, P<0.01) and in the incidence of ventricular fibrillation (from 64.3% to 16.7%, n=14 and 24, P<0.01) compared with the group injected with control adenovirus. Kallikrein gene delivery also attenuated programmed cell death in the ischemic area compared with the control area as assessed with the terminal deoxynucleotidyl transferase-mediated nick end labeling assay (n=6, P<0.01). Icatibant, a specific bradykinin B(2) receptor antagonist, abolished these kallikrein-mediated beneficial effects. The expression of human tissue kallikrein mRNA was identified in rat heart, kidney, lung, liver, and adrenal gland. After kallikrein gene delivery, cardiac kinin and cGMP levels were significantly elevated compared with the control (29.6+/-12.7 versus 6.1+/-2.1 pg/mg protein, n=7, P<0.01; 1.30+/-0.06 versus 0.86+/-0.09 pmol/mg protein, n=5, P<0.05). These results indicate that kallikrein gene delivery protects against myocardial infarction, ventricular arrhythmias, and apoptosis in ischemia/reperfusion injury via kinin-cGMP signal pathway. The successful application of this technology may have potential therapeutic value in the treatment of coronary artery diseases.

Polarized secretion of transgene products from salivary glands in vivo

Previously (Kagami et al. Hum. Gene Ther. 1996;7:2177-2184) we have shown that salivary glands are able to secrete a transgene-encoded protein into serum as well as saliva. This result and other published data suggest that salivary glands may be a useful target site for vectors encoding therapeutic proteins for systemic delivery. The aim of the present study was to assess in vivo if transgene-encoded secretory proteins follow distinct, polarized sorting pathways as has been shown to occur "classically" in cell biological studies in vitro. Four first-generation, E1-, type 5 recombinant adenoviruses were used to deliver different transgenes to a rat submandibular cell line in vitro or to rat submandibular glands in vivo. Subsequently, the secretory distribution of the encoded proteins was determined. Luciferase, which has no signal peptide, served as a cell-associated, negative control and was used to correct for any nonspecific secretory protein release from cells. The three remaining transgene products tested, human tissue kallikrein (hK1), human growth hormone (hGH), and human alpha1-antitrypsin (halpha1AT), were predominantly secreted (>96%) in vitro. Most importantly, in vivo, after a parasympathomimetic secretory stimulus, both hK1 and hGH were secreted primarily in an exocrine manner into saliva. Conversely, halpha1AT was predominantly secreted into the bloodstream, i.e., in an endocrine manner. The aggregate results are consistent with the recognition of signals encoded within the transgenes that result in specific patterns of polarized protein secretion from rat submandibular gland cells in vivo.

Role of the bradykinin B2 receptor in the maturation of blood pressure phenotype: lesson from transgenic and knockout mice

The binding of bradykinin (BK) to its B2 receptor results in a wide spectrum of biological effects including vasodilation, smooth muscle contraction and relaxation, pain, and inflammation. In order to gain a better insight into the physiological function of this potent vasoactive peptide, murine models have been created by the use of gene insertion or deletion. The results of studies using these strategies are revisited in the present article. In transgenic mice harboring the human BK B2 receptor cDNA (cHBKR), expression of the transgene was identified in the aorta, brain, heart, lung, liver, kidney, uterus and prostate gland by RT-PCR Southern blot analysis. These mice displayed an exaggerated hypotensive response to intra-aortic injection of BK, whereas the blood pressure of knockout mice, homozygous for targeted disruption of the endogenous gene, was insensitive to BK. Two transgenic mouse lines expressing the human BK B2 receptor showed a significant reduction of systolic tail-cuff blood pressure (84 +/- 1 mm Hg, n = 28; 80 +/- 1 mm Hg, n = 24; P < 0.001) compared with the control littermates (97 +/- 1 mm Hg, n = 52). Systolic blood pressure was elevated in BK B2 receptor knockout mice (124 +/- 1 mm Hg, n = 38). In heterozygous mice, systolic blood pressure was similar to that of controls until 5 month-old, then it raised to the elevated levels of knockout mice at 7 months of age. Together these data indicate that kinins acting through the B2 receptor play a role in the development of the blood pressure phenotype.

Adenovirus-mediated kallikrein gene transfer inhibits neointima formation via increased production of nitric oxide in rat artery

Tissue kallikrein cleaves kininogen substrate to produce vasoactive kinin peptides that have been implicated to play a role in the proliferation of vascular smooth muscle cells (VSMC). In order to explore potential roles of the kallikrein-kinin system in vascular biology, we evaluated the effects of adenovirus-mediated kallikrein gene delivery on neointima formation in balloon-injured rat artery. Infection of isolated rat aortic segments with adenovirus containing the human tissue kallikrein gene resulted in a time-dependent secretion of recombinant human tissue kallikrein, and significant increases in nitric oxide (NOx) and guanosine 3',5'-cyclic monophosphate (cGMP) levels post gene transfer. Human tissue kallikrein gene was delivered locally via adenoviral vectors into left common carotid artery after balloon angioplasty. Two weeks following gene transfer, we observed a 39% reduction in intima/media ratio at the injured vessel as compared to that of rats receiving control virus (n = 8, P < .01). Delivery of N(omega)-nitro-L-arginine methyl ester (L-NAME), a NOx synthase inhibitor via minipump for 2 weeks, blocked the protective effect and reversed the intima/media ratio to that of control rats (n = 5, P < .01). These results indicated that human tissue kallikrein gene delivery inhibits neointima formation via NO-cGMP signaling pathway. This study provides new insights into the role of the vascular kallikrein-kinin system and may have significant implications for gene therapy in treating occlusive vascular diseases.

Adenovirus-mediated kallikrein gene delivery attenuates hypertension and protects against renal injury in deoxycorticosterone-salt rats

To demonstrate potential therapeutic effects of kallikrein gene delivery in salt-induced hypertension and renal diseases, we delivered adenovirus carrying the human tissue kallikrein gene (Ad.CMV-cHK) into deoxycorticosterone acetate (DOCA)-salt hypertensive rats. A single intravenous injection of Ad.CMV-cHK caused a delay in the rise of blood pressure that began 2 days post gene delivery and lasted for more than 23 days. A maximal blood pressure reduction of 50 mm Hg was observed in rats receiving kallikrein gene delivery, as compared to rats receiving adenovirus containing the luciferase gene (Ad.CMV-Luc) (172 +/- 5 vs. 222 +/- 13 mm Hg, n = 6, P < 0.01). Throughout the experimental period, a blood pressure reduction of at least 32 mm Hg was observed in the DOCA-salt rats injected with Ad.CMV-cHK as compared to DOCA-salt rats receiving control adenovirus. Immunoreactive human tissue kallikrein levels were detected in rat serum and urine post gene delivery. Adenovirus-mediated kallikrein gene delivery caused a significant reduction in urinary excretion, urinary protein levels and body weight. Morphological examination of the kidney showed that kallikrein gene transfer significantly reduced DOCA-salt-induced glomerular sclerotic lesions, brush border disruption of proximal tubules, tubular dilatation and protein cast accumulation. These findings showed that the expression of human tissue kallikrein via gene delivery has protective effects against hypertension and renal injury in DOCA-salt hypertensive rats.

Immunohistochemical localization of kininogen in rat spinal cord and brain

Kininogen localization has been determined by immunocytochemistry in rat spinal cord and brain using a kinin-directed kininogen monoclonal antibody. In the spinal cord, there were immunostained neurons and fibers in laminae I, II, VII, and IX, intensely stained fibers in the superficial layers of the dorsal horn, and immunoreactive glial and endothelial cells. Small neurons, satellite cells, and Schwann cells immunostained distinctly in the dorsal root ganglion. In the brain stem, there were immunoreactive neurons and fibers in the tractus solitarius and nucleus, trigeminal spinal tract and nuclei, periaqueductal gray matter, vestibular nuclei, cochlear nuclei, trapezoid body, medial geniculate nucleus, and red nucleus. Immunostained neurons and fibers were also found in cerebellum (dentate nucleus), cerebral cortex (layers III and V), hippocampus (pyramidal cell layer), and corpus callosum. Glia and endothelial cells stained in all brain regions. The widespread location of kininogen in neurons and their processes, as well as in glial and endothelial cells, indicates more than one functional role, including those proposed as a mediator, a calpain inhibitor, and a kinin precursor, in a variety of neural activities and responses.

Kallikrein-binding protein is induced by growth hormone in the dwarf rat

Rat kallikrein-binding protein (KBP), a member of the serpin family, is a tissue kallikrein inhibitor. It has been shown to be a potential pathogenic factor of diabetic retinopathy and may play a role in animal development and growth. To determine whether reduced KBP expression is involved in retarded animal growth, we examined the in vivo effect of growth hormone (GH) deficiency on the expression of KBP in the Lewis dwarf (dw/dw). We found that serum levels of functionally active KBP were reduced in the dwarf rat (P < 0.05) as determined by complex formation assay between serum KBP and (125)I-labeled rat tissue kallikrein. Enzyme-linked immunosorbent assay showed that KBP levels were significantly reduced in the serum of the dwarf rat compared to the Lewis rat (213.8 ng/ml vs. 413.8 ng/ml, n = 4, P < 0.01). The decreased KBP levels were confirmed by Western blot analysis. Moreover, treatment of the dwarf rat with recombinant human GH for 4 wk resulted in a significant increase in KBP activity (P < 0.01) and serum KBP levels compared with the untreated dwarf rat (549.8 ng/ml, n = 5, vs. 213.8 ng/ml, n = 4, P < 0.02). Northern blot analysis and densitometry showed that liver KBP mRNA levels were reduced by fivefold in the dwarf rat compared to the Lewis rat and the decrease was reversed by the GH treatment. These results indicate that the KBP levels are regulated at the RNA level. Furthermore, in vitro studies using cultured rat hepatocytes showed that GH may have a direct regulatory effect on KBP expression since KBP levels increased in the conditioned media of cells treated with GH. These results demonstrated that KBP is reduced in the genetic dwarf rat and is restored to normal by GH; therefore, KBP is a GH-dependent protein and may be a new target for studying the mechanism of pathological animal growth.

Human tissue kallikrein attenuates hypertension and secretes into circulation and urine after intramuscular gene delivery in hypertensive rats

Systemic delivery of the human tissue kallikrein transgene has been shown to markedly delay the increase of blood pressure in hypertensive rat models. To demonstrate potential hypotensive effects of kallikrein via local delivery, adenovirus carrying the human tissue kallikrein gene was inoculated into quadriceps of spontaneously hypertensive rats (SHR). A single intramuscular injection of the kallikrein gene caused a significant delay of blood pressure increase for 5 weeks. The expression of human tissue kallikrein and its mRNA was identified solely in injected muscle. Immunoreactive human tissue kallikrein was detected in the muscle as well as in the circulation and urine of adult and newborn rats. Urinary kinin and cGMP levels increased significantly in rats receiving kallikrein gene delivery as compared with rats receiving control virus containing the LacZ gene. The detection of human tissue kallikrein in rat urine after local gene delivery into the muscle provides direct evidence that circulatory kallikrein can be secreted into the urine. These findings indicated that a continuous supply of human tissue kallikrein in the circulation is sufficient to reduce blood pressure and kallikrein gene delivery via the intramuscular route may have significant implications in therapeutic applications.

Adenovirus-mediated kallikrein gene delivery reduces aortic thickening and stroke-induced death rate in Dahl salt-sensitive rats

BACKGROUND AND PURPOSE

Kallikrein gene delivery has been shown to attenuate hypertension, cardiac hypertrophy, and renal injury in hypertensive animal models. The aim of this study was to investigate the potential protective effects of kallikrein gene delivery in salt-induced stroke and cerebrovascular disorders.

METHODS

Adenovirus harboring the human tissue kallikrein gene (AdCMV-cHK) was delivered intravenously into Dahl salt-sensitive (DS) rats after 4 weeks of high salt loading, and blood pressure was monitored weekly for 9 weeks.

RESULTS

A single injection of AdCMV-cHK caused a significant reduction of systolic blood pressure compared with that in control rats, with or without an injection of adenovirus carrying the LacZ (control) gene (AdCMV-LacZ). A maximal blood pressure reduction of 21 mm Hg was observed 2 weeks after gene delivery. The stroke mortality rate of DS rats (AdCMV-LacZ group versus the AdCMV-cHK group) was significantly decreased: 38% versus 9% at 3 weeks and 54% versus 27% at 5 weeks after gene delivery. Kallikrein gene delivery significantly attenuated salt-induced aortic hypertrophy, as evidenced by reduced thickness of the aortic wall. Recombinant human tissue kallikrein was detected in rat serum and urine after gene transfer. Kinin-releasing activities in the brain as well as urinary kinin and cGMP levels were significantly increased in rats receiving the kallikrein gene.

CONCLUSIONS

This is the first study to demonstrate the protective effect of kallikrein gene delivery in reducing salt-induced stroke mortality and vascular dysfunction.

Kallikrein gene delivery inhibits vascular smooth muscle cell growth and neointima formation in the rat artery after balloon angioplasty

Tissue kallikrein cleaves kininogen substrate to produce vasoactive kinin peptides that have been implicated in the proliferation of vascular smooth muscle cells (VSMCs). To explore potential roles of the kallikrein-kinin system in vascular biology, we evaluated the effects of adenovirus-mediated human kallikrein gene delivery on the growth of primary cultured VSMCs and in balloon-injured rat artery in vivo. Kallikrein gene transfer into cultured rat VSMCs resulted in time-dependent secretion of recombinant human tissue kallikrein and inhibition of cell proliferation. Balloon angioplasty reduced endogenous rat tissue kallikrein mRNA and protein levels at the injured site. In rats that received adenovirus-mediated human kallikrein gene delivery, we observed a 39% reduction in intima/media ratio at the injured vessel after delivery compared with that of rats that received control virus (n=8, P<0.01). Icatibant, a specific bradykinin B(2) receptor antagonist, blocked the protective effect and reversed the intima/media ratio to that of the control rats (n=5, P<0.01). After gene delivery, human kallikrein mRNA was identified at the injured vessel and a 3-fold increase occurred in kininogenase activity. cAMP and cGMP levels in balloon-injured aorta increased significantly at 4, 7, and 14 days after kallikrein gene delivery, but icatibant abolished the increase. These results provide new insights into the role of the vascular kallikrein-kinin system and have significant implications for gene therapy to treat restenosis or atherosclerosis.

Identification of pharmacokinetically stable 3, 10-dibromo-8-chlorobenzocycloheptapyridine farnesyl protein transferase inhibitors with potent enzyme and cellular activities

Farnesyl protein transferase (FPT) is a promising target for the development of cancer chemotherapeutics because it is responsible for the farnesylation of oncogenic p21 Ras proteins which are found in nearly 30% of all human cancers and necessary for cellular development and growth. The recent discovery and progression to phase II clinical trials of trihalobenzocycloheptapyridine Sch-66336 as a potent inhibitor of FPT with oral, in vivo efficacy in mice have spawned extensive structure-activity relationship studies (SAR) of this class of compounds. Of the many trihalobenzocycloheptapyridine analogues prepared, we have identified several which inhibit FPT and cellular proliferation at single-digit nanomolar concentrations and which have good pharmacokinetic properties in mice.

Atrial natriuretic peptide gene delivery attenuates gentamycin-induced nephrotoxicity in rats

BACKGROUND

Atrial natriuretic peptide (ANP) is a cardiac hormone which exerts potent natriuretic and vasorelaxant activities. The aim of this study is to investigate potential protective effects of ANP gene delivery in gentamycin-induced nephrotoxicity.

METHODS

Adenovirus (Ad.RSV-ANP) carrying the human ANP gene or carrying the LacZ gene (Ad.RSV-LacZ) under the control of the Rous sarcoma virus promoter were delivered intravenously on the first day of gentamycin administration. Sprague Dawley rats were injected subcutaneously with gentamycin daily for 10 days.

RESULTS

A single systemic injection of Ad.RSV-ANP at a dose of 1.2x10(10) pfu results in a significant increase in urine excretion, water intake, urinary sodium and potassium excretion. Adenovirus-mediated ANP gene delivery significantly increased renal blood flow, glomerular filtration rates and urine flow as well as attenuated the elevation of blood urea nitrogen levels. Histological evaluations revealed that ANP delivery attenuated gentamycin-induced renal tubular damage, cellular necrosis, and lumenal protein casts. The expression of human ANP mRNA was identified in rat kidney, heart, aorta and liver. Immunoreactive human ANP was detected in the heart and kidney of rats injected with Ad.RSV-ANP but not in rats injected with Ad.RSV-LacZ. Cyclic GMP levels in the kidney were significantly increased in rats receiving ANP gene delivery.

CONCLUSIONS

This study shows that ANP gene delivery exhibits protection against gentamycin-induced nephrotoxicity and raises the potential to use ANP gene therapy for the treatment of drug-induced renal failure.

Specificity of human tissue kallikrein towards substrates containing Phe-Phe pair of amino acids

We have explored in detail the determinants of specificity for the hydrolysis by human tissue kallikrein (hK1) of substrates containing the Phe-Phe amino acid pair, after which hK1 cleaves kallistatin (human kallikrein-binding protein), a specific serpin for this protease, as well as somatostatin 1-14. Internally quenched fluorogenic peptides were synthesized with the general structure Abz-peptidyl-EDDnp [Abz, o-aminobenzoic acid; EDDnp, N-(2, 4-dinitrophenyl)ethylenediamine], based on the natural reactive-centre loop sequence of kallistatin from P9 to P'13, and the kinetic parameters of their hydrolysis by hK1 were determined. All these peptides were cleaved after the Phe-Phe pair. For comparison, we have also examined peptides containing the reactive-centre loop sequences of human protein-C inhibitor (PCI) and rat kallikrein-binding protein, which were hydrolysed after Phe-Arg and Leu-Lys bonds, respectively. Hybrid peptides containing kallistatin-PCI sequences showed that the efficiency of hK1 activity on the peptides containing kallistatin and PCI sequences depended on both the nature of the P1 amino acid as well as on residues at the P- and P'-sides. Moreover, we have made systematic modifications on the hydrophobic pair Phe-Phe, and on Lys and Ile at the P3 and P4 positions according to the peptide substrate, Abz-AIKFFSRQ-EDDnp. All together, we concluded that tissue kallikrein was very effective on short substrates that are cleaved after the Phe-Arg pair; however, hydrolysis after Phe-Phe or other hydrophobic pairs of amino acids was more restrictive, requiring additional enzyme-substrate interaction and/or particular substrate conformations.

Potassium supplement upregulates the expression of renal kallikrein and bradykinin B2 receptor in SHR

High potassium intake is known to attenuate hypertension, glomerular lesion, ischemic damage, and stroke-associated death. Our recent studies showed that expression of recombinant kallikrein by somatic gene delivery reduced high blood pressure, cardiac hypertrophy, and renal injury in hypertensive animal models. The aim of this study is to explore the potential role of the tissue kallikrein-kinin system in blood pressure reduction and renal protection in spontaneously hypertensive rats (SHR) on a high-potassium diet. Young SHR were given drinking water with or without 1% potassium chloride for 6 wk. Systolic blood pressure was significantly reduced beginning at 1 wk, and the effect lasted for 6 wk in the potassium-supplemented group compared with that in the control group. Potassium supplement induced 70 and 40% increases in urinary kallikrein levels and renal bradykinin B2 receptor density, respectively (P < 0.05), but did not change serum kininogen levels. Similarly, Northern blot analysis showed that renal kallikrein mRNA levels increased 2.7-fold, whereas hepatic kininogen mRNA levels remained unchanged in rats with high potassium intake. No difference was observed in beta-actin mRNA levels in the kidney or liver of either group. Competitive RT-PCR showed a 1.7-fold increase in renal bradykinin B2 receptor mRNA levels in rats with high potassium intake. Potassium supplement significantly increased water intake, urine excretion, urinary kinin, cAMP, and cGMP levels. This study suggests that upregulation of the tissue kallikrein-kinin system may be attributed, in part, to blood pressure-lowering and diuretic effects of high potassium intake.

Localization and expression of tissue kallikrein and kallistatin in human blood vessels

Tissue kallikrein releases kinins by specific proteolysis, an activity inhibited by kallistatin. In this study, kallikrein and kallistatin were localized to endothelial and smooth muscle cells of large, medium, and small normal blood vessels by immunohistochemical techniques. Immunostaining for both proteins was strong in the endothelium of all sizes of blood vessels and was more intense in medial smooth muscle cells of small and medium-sized blood vessels than in elastic arteries. The sites of synthesis by endothelial and smooth muscle cells were demonstrated in normal blood vessels of all sizes by in situ hybridization histochemistry. Kallikrein and kallistatin levels were measured by immunoassays in homogenates of human aorta, vena cava, and iliac artery and vein. Tissue kallikrein and kallistatin transcripts were identified in human blood vessels by RT-PCR followed by Southern blot analysis with specific oligonucleotide probes. The results demonstrated the expression and co-localization of tissue kallikrein and kallistatin in human vessels and suggest a potential role of kallistatin in regulating tissue kallikrein in blood vessels.

Atrial natriuretic peptide gene delivery reduces stroke-induced mortality rate in Dahl salt-sensitive rats

Atrial natriuretic peptide (ANP) is a powerful hormone with hypotensive, natriuretic, diuretic, and many other beneficial effects. Direct infusion of ANP in therapeutics has limited success because of its short half-life in the circulation. Our previous studies have shown that ANP gene delivery attenuates hypertension, cardiac hypertrophy, and renal injury in Dahl salt-sensitive (Dahl-SS) rats. To investigate the potential therapeutic value of ANP gene delivery on salt-induced stroke and cerebrovascular disorders, an adenovirus harboring the human ANP gene (Ad.RSV-cANP) was injected into Dahl-SS rats on a high salt diet. A single intravenous injection of the ANP gene caused a significant reduction of blood pressure that lasted for more than 3 weeks. A maximal blood pressure reduction of 28 mm Hg was observed 2 weeks after gene delivery as compared with that of control rats injected with adenovirus harboring the LacZ gene under the control of the Rous sarcoma virus promoter (Ad.RSV-LacZ). Immunoreactive human ANP can be detected in the heart, lung, kidney, and brain of rats after gene delivery. The stroke mortality rate of Dahl-SS rats was significantly decreased (from 54% to 17% at 3 weeks and from 70% to 50% at 4 weeks after ANP gene delivery as compared with rats injected with control virus). ANP gene delivery also significantly attenuates salt-induced aortic hypertrophy as evidenced by reduced thickness of the aortic wall. This is the first study to demonstrate the potential of ANP gene delivery in reducing the mortality rate caused by cerebrovascular disorders and stroke. Successful application of this technology may have potential value in treating individuals with a high risk of stroke.

Molecular cloning and expression of rat bradykinin B1 receptor

The gene encoding rat bradykinin B1 receptor has been cloned by using a partial rat B1 cDNA probe. The rat B1 receptor gene contains two exons and the entire coding region is within the second exon. The 5'-flanking region of the rat B1 receptor gene contains several putative transcriptional regulatory sites including TATA box, cAMP response element, NF-kappaB and AP-1. It showed promoter activity inducible by lipopolysaccharide in vascular smooth muscle cells. Rat B1 receptor mRNA was found to be alternatively spliced and induced by lipopolysaccharide treatment in a wide range of tissues, such as the salivary gland, testis, kidney, lung, heart, prostate and aorta. The deduced rat B1 receptor amino acid sequence is 71% homologous to human and rabbit counterparts, and 89% homologous to the mouse counterpart. The expressed B1 receptor in HEK293 cells displayed a rank order of affinity for the kinin peptides: des-Arg9-BK>Lys-des-Arg9-BK approximately des-Arg9, Leu8-BK>Sar-Tyr-epsilonAhx-Lys-[D-betaNal7, Ile8]-des-Arg9-BK>Sar-Tyr-epsilonAhx-Lys-des-Arg9-BK>>BK>> Hoe140. These results indicate that the cloned gene encodes a functional rat B1 receptor.

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.

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.

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.

[Pharmacognostical identification of Chinese drug wuxiangcao (Mosla soochowensis)]

In this paper, Chinese drug Wuxiangcao (Mosla soochowensis Matsuda) is made an initial study on character, microscopical and physicochemical sides. It provide a scientific basis for its comprehensive devlopment and ultilization, and to use in clinical.

Atrial natriuretic peptide gene delivery attenuates hypertension, cardiac hypertrophy, and renal injury in salt-sensitive rats

To investigate potential therapeutic effects of atrial natriuretic peptide (ANP) gene delivery on renal and cardiac disorders, adenovirus harboring the human ANP gene (Ad.RSV-cANP) was delivered into Dahl salt-sensitive (DSS) rats on a high-salt diet. A single intravenous injection of the ANP gene caused a significant delay of blood pressure increase 3 days post-injection and the effect lasted for more than 5 weeks. A maximal blood pressure reduction of 32.8 mmHg was observed after ANP gene delivery, as compared with that of control rats injected with Ad.CMV-LacZ. Immunoreactive human ANP can be detected in the heart, lung, and kidney of rats after gene delivery. ANP gene delivery caused significant increases in renal blood flow, glomerular filtration rate, sodium output, urine excretion, and urinary cGMP levels. These beneficial effects were reflected morphologically by a reduction in cardiomyocyte size, attenuation of the glomerular-sclerotic lesions, tubular injury and arterial thickening. This study demonstrated the usefulness of somatic gene transfer as a new tool for ANP gene delivery in studying salt-related hypertension and renal and cardiovascular diseases. In addition, the findings also suggest that ANP gene delivery may have potential in therapeutic applications.

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.

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.

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.

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.

Central delivery of human tissue kallikrein gene reduces blood pressure in hypertensive rats

The human tissue kallikrein gene, in the form of naked DNA (CMV-cHK) or an adenoviral vector (Ad.CMV-cHK), was directly delivered by intracerebroventricular injection into spontaneously hypertensive rats. Control rats received the same amount of vector DNA (pcDNA3) or adenoviral vector (Ad.CMV-LacZ) carrying the lacZ gene. A single injection of the human tissue kallikrein gene caused a rapid and prolonged blood pressure-lowering effect that began 1 day post injection and the effect lasted for more than 7 days. The expression of human tissue kallikrein and its mRNA was identified in the cortex, cerebellum, brain stem, hippocampus and hypothalamus. Cellular localization of beta-galactosidase was detected by X-gal staining in the thalamus, hypothalamus and third ventricle in rats injected with Ad.CMV-LacZ. This suggests that the tissue kallikrein-kinin system may function in the central control of blood pressure homeostasis.

Transcription factor nuclear factor kappaB regulates the inducible expression of the human B1 receptor gene in inflammation

Expression of the bradykinin B1 receptor gene is up-regulated in vascular smooth muscle cells (VSMCs) in response to a variety of inflammatory stimuli. We isolated the 5'-flanking region of the human bradykinin B1 receptor gene and examined its promoter activity by transient transfection analysis. This region (-2582 to +34) showed promoter activity inducible by lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha), and interleukin-1beta (IL-1beta) in VSMCs. Further deletion analysis revealed that constructs containing 111 base pairs of 5'-flanking sequence were sufficient for transcriptional induction. Mutagenesis of a nuclear factor kappaB (NF-kappaB)-like site at -64 to -55 abolished most of the LPS, TNF-alpha, and IL-1beta inducibility, whereas a mutation of a cyclic AMP response element at -50 to -43 markedly reduced the basal promoter activity, and a mutation of the activator protein 1 (AP-1) site at -78 to -72 had minimal effects. Nuclear extracts from LPS, TNF-alpha, and IL-1beta-treated VSMCs, IL-1beta-treated human hepatoma HepG2, and human lung fibroblast IMR-90 cells showed strong inducible binding activity to the NF-kappaB-like site by gel shift assays. These results demonstrated that NF-kappaB-like nuclear factor was involved in the inducible expression of the human bradykinin B1 receptor gene during inflammatory processes.

Human kallikrein gene delivery attenuates hypertension, cardiac hypertrophy, and renal injury in Dahl salt-sensitive rats

The tissue kallikrein-kinin system has been documented to be involved in the pathogenesis of hypertension and renal diseases. To investigate the protective effects of kallikrein gene delivery on salt-induced renal damage, cardiac dysfunction, and hypertension, adenovirus harboring the human tissue kallikrein gene under the control of the cytomegalovirus promoter Ad.CMV-cHK was delivered into Dahl salt-sensitive (Dahl-SS) rats fed to a high-salt (4% NaCl) diet. A single intravenous injection of Ad.CMV-cHK resulted in a significant reduction of blood pressure beginning 2 days post injection and the effect lasted for 4 weeks. The human kallikrein mRNA was detected in rat heart, kidney, lung, liver, and adrenal gland; immunoreactive human kallikrein can be measured in the liver, kidney, sera, and urine of rats receiving kallikrein gene delivery. Following Ad.CMV-cHK injection, a significant increase in urine excretion, urinary sodium output, kinin, and cGMP level was observed. Kallikrein gene delivery caused a significant reduction in the left ventricular mass and cardiomyocyte size as well as inhibition of glomerular sclerotic lesions and tubular dilatation. This study shows that adenovirus-mediated gene delivery in Dahl-SS rats fed a high-salt diet resulted in (i) prolonged reduction of blood pressure and increased urinary kinin and cGMP levels, consistent with blood pressure reductions mediated via kinin through a cGMP-dependent signal transduction pathway, (ii) inhibition of cardiac hypertrophy, and (iii) attenuation of renal injury. The ability of kallikrein gene transfer 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.

Adrenomedullin gene delivery reduces blood pressure in spontaneously hypertensive rats

Adrenomedullin (ADM) is a potent vasoactive peptide. In this study, we explored the effects of a continuous supply of ADM by somatic gene delivery on spontaneously hypertensive rats (SHR). DNA constructs containing the human ADM cDNA fused to either the cytomegalovirus promoter (CMV-cADM) or Rous Sarcoma virus 3'-long terminal repeat (RSV-cADM) were intravenously injected into SHR through the tail vein. Expression of human ADM in SHR was identified in the kidney, adrenal gland, heart, and lung by radioimmunoassay and reverse transcription-polymerase chain reaction followed by Southern blot analysis. A single injection of ADM plasmid DNA in young adult SHR (7 wk old) caused a significant reduction in systolic blood pressure for up to 5 wk (p < 0.05). A second injection of CMV-cADM 5 wk after the first delivery resulted in a further reduction in blood pressure for another 3 wk (p < 0.001). A maximal blood pressure reduction of 22 mmHg in SHR was observed 7 wk after injection of CMV-cADM plasmid DNA (185 +/- 1.7 mmHg, n = 6, p < 0.001), and a reduction of 15 mmHg was observed after injection of RSV-cADM (192 +/- 2.7 mmHg, n = 6, p < 0.001), as compared with control rats given vector DNA (207 +/- 2.4 mmHg, n = 6). Similarly, injection of CMV-cADM plasmid DNA in adult SHR (10 wk old) resulted in a significant reduction in blood pressure for up to 6 wk. Antibodies to either human ADM or its plasmid DNA were not detected in rat sera after the second injection. These studies indicate that intravenous injection of the human ADM gene in hypertensive rats results in expression of the foreign gene and induces a long-lasting reduction in blood pressure.

The enzymic potential of tissue kallikrein (rK1) in rat submandibular saliva depends on whether it was secreted via constitutive or regulated pathways

The enzymic activity and immunoreactivity of rat tissue kallikrein (rK1) secreted at rest by granular duct cells of unstimulated submandibular glands has been compared with that secreted on autonomic nerve stimulation. Although a direct vesicular, constitutive secretory pathway operates for rK1 secretion from granular duct cells of unstimulated and parasympathetically stimulated glands the rK1 was not present in a pro-form and actually showed a greater enzymic activity per unit immunoreactive protein than the granule-derived rK1 in sympathetically evoked saliva. Constitutively secreted rK1 was found to be in a single chain molecular form by reducing SDS gel electrophoresis. In contrast rK1 secreted from the storage granule pool of granular duct cells on sympathetic nerve stimulation was present in much higher amounts and occurred in both one-chain and two-chain forms as revealed by SDS gel electrophoresis under reducing conditions. The lower enzymic potential of rK1 in sympathetically evoked saliva might be accounted for by its conversion to a two-chain form.

Effect of cyclosporin A on the expression of tissue kallikrein, kininogen, and bradykinin receptor in rat

The tissue kallikrein-kinin system is involved in vasodilation and blood pressure regulation. In the present study, we investigated the effects of chronic cyclosporin A (CsA) administration on blood pressure and the expression of tissue kallikrein, kininogen, and bradykinin receptor in normotensive Wistar rats. Chronic administration of CsA significantly increased systolic blood pressure compared with control rats (n = 6, P < 0.01), although body weight was significantly lower than control rats (n = 6, P < 0.01). The development of hypertension was accompanied by the altered expression of kallikrein-kinin system components. Immunoreactive renal kallikrein and urinary excretion of tissue kallikrein levels were increased by chronic administration of CsA (n = 5 or 6, P < 0.05). Levels of N-tosyl-L-phenylalanine chloromethyl ketone-trypsin and kallikrein-releasable kininogens in sera increased in response to chronic CsA treatment (n = 5 or 6, P < 0.05). Chronic CsA treatment significantly increased renal kallikrein, bradykinin B2 receptor, and hepatic kininogen mRNA levels. The increased levels of tissue kallikrein-kinin system components were accompanied by significant increases in 24-h urine excretion and water intake after chronic CsA treatment (n = 5, P < 0.05). These results suggest that enhanced activity of the tissue kallikrein-kinin system may compensate for the CsA-induced vasoconstriction and hypertension.

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.

The effect of bradykinin on secretion of insulin, glucagon, and somatostatin from the perfused rat pancreas

To evaluate the effect of bradykinin (BK) on rat islet alpha, beta, and delta cells, the rat pancreas was perfused in situ with BK (1 mumol/L) for 30 minutes via a cannula placed in the celiac artery. Insulin, glucagon, and somatostatin concentrations in the effluent were measured to determine the effect of BK on the secretion of these hormones. The BK concentration of the rat pancreas was also measured. Basal secretion of insulin, glucagon, and somatostatin in medium containing 6 mmol/L glucose was maintained at 6.5 +/- 0.5 ng/mL 124 +/- 8 pg/mL, and 511 +/- 22 pg/mL (n = 12), respectively. BK (1 mumol/L) induced a transient peak that was 3.7-fold of the baseline concentration within 3 minutes, followed by a sustained level that was approximately 50% higher than baseline. BK also transiently increased glucagon secretion with a peak that was 1.7-fold of the baseline concentration within 3 minutes, without a sustained secretion phase. BK caused a reduction in somatostatin secretion within 3 minutes to a level of 60% to 70% of the baseline concentration. The BK concentration of the rat pancreas was 3.42 +/- 1.45 micrograms/g protein (n = 5), which was approximately 3 mumol/L. We concluded that BK stimulated insulin secretion, transiently increased glucagon secretion, and decreased somatostatin secretion during the 30-minute perfusion of the rat pancreas.

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.

Prolonged reduction of high blood pressure with human nitric oxide synthase gene delivery

Endothelium-derived nitric oxide (NO) in peripheral vessels has been shown to modulate vascular resistance and blood pressure. We explored the effect of a continuous supply of human endothelial NO synthase (eNOS) on the blood pressure of spontaneously hypertensive rats (SHR) by somatic gene delivery. A DNA construct containing the human eNOS gene fused to the cytomegalovirus promoter/enhancer was injected into SHR through the tail vein. A single injection of the naked eNOS plasmid DNA caused a significant reduction of systemic blood pressure for 5 to 6 weeks in SHR, and the effect continued for up to 10 to 12 weeks after a second injection. The differences were significant from 2 to 12 weeks postinjections (n=6, P<.01). In a separate experiment, L-arginine, the substrate of eNOS, was supplied in drinking water at a concentration of 7.5 g/L for 11 weeks after eNOS gene delivery. A maximal blood pressure reduction of 21 mm Hg in SHR was observed with eNOS DNA compared with that of control SHR injected with vector DNA (181.9+/-1.46 versus 202.7+/-2.79 mm Hg, mean+/-SEM, n=6, P<.01). Human eNOS gene delivery induces significant increases in urinary and aortic cGMP levels and urinary and serum nitrite/nitrate content (P<.05), while no significant differences in body weight, heart rate, water intake, food consumption, or urine excretion were observed. These results indicate that somatic delivery of the human eNOS gene induces a prolonged reduction of high blood pressure and raises the potential of using eNOS gene therapy for hypertension and cardiovascular diseases.

Distribution of tissue kallikreins in lower vertebrates: potential physiological roles for fish kallikreins

Fish skeletal muscle prokallikrein was purified from black sea bass, Centropritis striata, and used for the production of polyclonal antiserum. Tissue proteins from primitive fish and teleosts, an alligator, and an insectivore were resolved by sodium dodecylsulfate-polyacrylamide gel electrophoresis, Western blotted, and probed with fish muscle prokallikrein antiserum. A recurring theme was the presence of approximately 36 and 72 kDa kallikrein-like proteins in skeletal muscle, heart, gill, kidney, and spleen of higher teleosts and in selected tissues of sturgeon, shark, alligator, and mole. The presence of immunoreactive kallikreins in osmoregulatory organs such as the gills of teleosts and the rectal gland of sharks signifies a potential role for these proteins in osmoregulation. Black sea bass, rock bass, and sturgeon contained many immunoreactive kallikreins in their swimbladders, which implicates a role for kallikreins in the regulation of blood flow and vascular permeability to facilitate gas exchange within the bladder. Kallikreins were consistently identified in skeletal muscle and heart of all the species evaluated and may regulate local blood flow, muscle contraction or relaxation, or participate in various transport processes. The antiserum to fish prokallikrein recognized immunoreactive kallikreins from pancreatic tissues from fish and lower vertebrates, but not from the pyloric caecum of sea bass. The wide distribution of tissue kallikrein in lower vertebrates suggests that it may participate in a variety of physiological functions.

Purification, characterization and activation of fish muscle prokallikrein

Fish prokallikrein was isolated and characterized from skeletal muscle of the black sea bass, Centropristis striata. The prokallikrein was purified to apparent homogeneity by anion exchange perfusion chromatography and reversed phase high performance liquid chromatography. Initial identification was by its weak immunoreactivity with human tissue kallikrein antiserum. Two-dimensional gel electrophoresis and immunoblotting identified the protein as 36 kDa with a pI of 4.95-5.15. The prokallikrein was trypsin-activated to produce an approximately 36 kDa active enzyme as identified on an SDS-polyacrylamide gel overlayed with a membrane impregnated with the fluorogenic tripeptidyl substrate D-Val-Leu-Arg-7-amino-4-trifluoromethyl-coumarin. A potential dimer at 72 kDa was also enzymatically active. Bass kallikrein cleaved low molecular weight dog kininogen to release kinin peptide as determined by radioimmunoassay. The enzyme's amidolytic activity, with a pH optimum at 9.0, was inhibited by aprotinin, benzamidine, and phenylmethanesulphonyl fluoride, but not by elastatinal, soybean trypsin inhibitor, or limabean trypsin inhibitor. Polyclonal antiserum raised against the purified bass muscle prokallikrein recognized 36 kDa and 72 kDa proteins in bass heart, skeletal muscle, spleen, swimbladder, gill, and kidney by Western blot analyses. The wide distribution of immunoreactive proteins in the tissues suggests a potential physiological role for fish kallikreins in muscle contraction and/or relaxation, the regulation of local blood flow, and in osmoregulation. The detection of fish prokallikrein and its activation leads the way for an evaluation of the impact of kallikreins in fish health and disease processes and for studying the evolution of kallikreins and related serine proteinases.

Regulation of bradykinin B2-receptor expression by oestrogen

1. Tissue kallikrein is overexpressed in the kidney of female rats, this sexual dimorphism being associated with a greater effect of early blockade of bradykinin B2-receptors on female blood pressure phenotype. We evaluated the effect of ovariectomy and oestradiol benzoate (50 micrograms kg-1 every two days for two weeks) on the vasodepressor response to intra-arterial injection of bradykinin (150-900 ng kg-1) and on the expression of bradykinin B2-receptors. 2. Ovariectomy reduced the magnitude of the vasodepressor response to bradykinin and unmasked a secondary vasopressor effect. Oestrogen replacement restored the vasodepressor response to bradykinin in ovariectomized rats. 3. The vasodepressor responses to sodium nitroprusside (3-18 micrograms kg-1), acetylcholine (30-600 ng kg-1), desArg9-bradykinin (150-900 ng kg-1) or prostaglandin E2 (30-600 ng kg-1) were significantly reduced by ovariectomy. Oestrogen restored to normal the responses to desArg9-bradykinin, acetylcholine and prostaglandin E2, but not that to sodium nitroprusside. 4. B2-receptor mRNA levels were decreased by ovariectomy in the aorta and kidney and they were restored to normal levels by oestrogen. Neither ovariectomy nor oestradiol affected receptor expression in the heart and uterus. 5. These results indicate that oestrogen regulates B2-receptor gene expression and function. Since kinins exert a cardiovascular protective action, reduction in their vasodilator activity after menopause might contribute to the increased risk of pathological cardiovascular events. Conversely, the cardioprotective effects of oestrogen replacement might be, at least in part, mediated by activation of the kallikrein-kinin system.

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.

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.