Two cases of primary thyroid disease and hip fracture

Although the exact mechanism is not fully understood, some skeletal abnormalities are reported in patients with primary thyroid disease (McLean and Podell, 1995; Rosen, 1997). Prompt and adequate medication may improve the prognosis. This article describes the clinical course of two patients with primary thyroid disease and reviews thyroid hormone-related skeletal problems.

p107 Expression in colorectal tumours rises during carcinogenesis and falls during invasion

p107 Links to cyclin A/CDK2 (cyclin-dependent kinase 2) and cyclin E/CDK2 that are important cell cycle regulators. However, p107 expression remains unclear in almost all kinds of human solid tumours. To clarify the expression of p107 in colorectal tumours, 22 normal mucosae, 9 hyperplastic polyps, 60 adenomas, 198 primary carcinomas, 21 lymph-nodal metastases, and 10 hepatic metastases were immunohistochemically stained for p107, cyclin A, cyclin E, CDK2 and Ki67. Results were measured using labelling indices (LIs). p107 LIs surpassed the highest value in normal tissues in six of nine hyperplastic polyps, 54 of 60 adenomas, 144 of 198 primary cancers, 13 of 21 nodal foci and three of 10 hepatic foci. p107 LIs also apparently rose from normal through hyperplasia and adenoma to early carcinoma. However, they declined in liver-metastatic foci, and in primary cancers showing large size, mucinous type, venous invasion, lymphatic invasion, poorly differentiated type, deep invasion, lymph-nodal metastasis, hepatic metastasis or advanced stage. Low p107 LIs were also linked to a poor survival, particularly in stage-III patients. As the p107 LI gradually rose, the CDK2 (in primary cancers only), cyclin A, cyclin E and Ki67 LIs were elevated concurrently-in both adenomas and primary cancers. Thus, in colorectal tumours, p107 expression rises abnormally and gradually during carcinogenesis and then falls during invasion, and thereby probably perturbs the cell-cycle control and promotes carcinogenesis and invasion. Clinically, reduced p107 may indicate a poorer prognosis.

Current epidemiological trend of tuberculosis in Japan

OBJECTIVE

To observe the recent epidemiological trend of tuberculosis and to determine the factors related to the deteriorating trend in incidence and mortality rates in Japan.

DESIGN

Descriptive analyses of tuberculosis notification rates and mortality rates by age, sex, year and birth-cohort.

RESULTS

The decline in the tuberculosis notification rate has started slowing down since around 1980. Among the cohorts born before 1950, the trend of notification rate by age has levelled off since around 1980. The reduction in the tuberculosis mortality rate has also recently begun to slow down, but later and to a lesser extent than that of the notification rate. Although deaths due to tuberculosis occur mostly among the elderly, the rate of decline in mortality among middle-aged males has slowed down recently. The trend in the mortality rate of birth-cohorts has recently shown an upward trend with age.

CONCLUSION

A major cause of the current stagnation of the decline in notification rates is the increase in the elderly population with a high prevalence of tuberculosis infection in the past, who are more likely to develop the disease as they approach biological senescence. Other possible causes are a gradual shift of the tuberculosis problem to socio-economically deprived segments of the urban population, and behavioural changes causing delay in case-finding.

Characterization of genes encoding multi-domain proteins in the genome of the filamentous nitrogen-fixing Cyanobacterium anabaena sp. strain PCC 7120

Computational analysis of gene structures in the genome of Anabaena sp. PCC 7120 revealed the presence of a large number of genes encoding proteins with multiple functional domains. This was most evident in the genes for signal transduction pathway and the related systems. Comparison of the putative amino acid sequences of the gene products with those in the Pfam database indicated that and PAS domains which may be involved in signal recognition were extremely abundant in Anabaena: 87 GAF domains in 62 ORFs and 140 PAS domains in 59 ORFs. As for the two-component signal transduction system, 73, 53, and 77 genes for simple sensory His kinases, hybrid His kinases and simple response regulators, respectively, many of which contained additional domains of diverse functions, were presumptively assigned. A total of 52 ORFs encoding putative Hanks-type Ser/Thr protein kinases with various domains such as WD-repeat, GAF and His kinase domains, as well as genes for presumptive protein phosphatases, were also identified. In addition, genes for putative transcription factors and for proteins in the cAMP signal transduction system harbored complex gene structures with multiple domains.

Different effects of St John's wort on the pharmacokinetics of simvastatin and pravastatin

OBJECTIVE

St John's Wort, a widely used herbal product, is an inducer of CYP3A4 and it decreases blood concentrations of CYP3A4 substrates. The effects of St John's Wort on the pharmacokinetics of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors simvastatin (an inactive lactone pro-drug) and pravastatin were determined in this study.

METHODS

Sixteen healthy male subjects (n = 8 in group 1 and n = 8 in group 2) took a St John's Wort caplet (300 mg) or matching placebo three times a day for 14 days in a double-blind, crossover study. On day 14, a single oral dose of 10 mg simvastatin and 20 mg pravastatin was given to subjects in group 1 and group 2, respectively. Blood samples were obtained during a 24-hour period after the administration of each drug.

RESULTS

Repeated St John's Wort treatment tended to lower plasma simvastatin concentration and significantly (P <.05) lowered concentrations of simvastatin hydroxy acid, its active metabolite. The peak concentration in plasma (ratio, 0.72 of placebo) of simvastatin hydroxy acid tended to be decreased and its area under the plasma concentration-time curve between time zero and 24 hours after administration (ratio, 0.48 of placebo) was significantly decreased (P <.05) by St John's Wort. On the other hand, St John's Wort did not influence plasma pravastatin concentration. No significant differences were observed in the elimination half-life of simvastatin or pravastatin between the placebo and St John's Wort trials.

CONCLUSIONS

This study showed that St John's Wort decreases plasma concentrations of simvastatin but not of pravastatin. Because simvastatin is extensively metabolized by CYP3A4 in the intestinal wall and liver, which are induced by St John's Wort, it is likely that this interaction is partly caused by the enhancement of the CYP3A4-mediated first-pass metabolism of simvastatin in the small intestine and liver.

Expression of cyclin E and cyclin-dependent kinase 2 correlates with metastasis and prognosis in colorectal carcinoma

The expression of cyclin E and cyclin-dependent kinases 2 (CDK2) in metastatic foci, the relationship of their expression with some clinicopathologic characteristics, and the correlation of their expression with prognosis remain unclear. To examine the roles of their expression in the progression of colorectal carcinoma, 21 normal mucosa, 9 hyperplastic polyps, 58 adenomas, 17 adenocarcinoma in adenomas, 203 primary cancers, 21 lymph node metastases, and 10 hepatic metastases were immunohistochemically stained with anti-cyclin E, anti-CDK2, and anti-Ki67 antibodies. In the carcinogenic process, both cyclin E and CDK2 expressions increased significantly. From the primary to the lymph node-metastatic foci, cyclin E protein remained unchanged, but CDK2 increased significantly. From the primary to the liver-metastatic foci, cyclin E apparently decreased, and CDK2 was reduced almost to zero. In primary carcinomas, the reduction of cyclin E was significantly associated with large tumor size, mucinous type, venous invasion, deep infiltration, lymph nodal metastasis, peritoneal metastasis, advanced stage, and poor prognosis. Decreased CDK2 was obviously correlated with large tumor size, venous invasion, deep infiltration, hepatic metastasis, advanced stage, and poor prognosis. Increased cyclin E protein was related to elevated CDK2, which was further linked to higher Ki67. Thus, CDK2 overexpression could facilitate lymph node metastasis. The overexpression of cyclin E and CDK2 may mainly promote the progression of early cancer. Anti-cyclin E or anti-CDK2 chemotherapy should be targeted to the cancers with such overexpression.

Dosing time-dependent effect of trandolapril on the prevention of cardiac hypertrophy in rats with aortic banding

Trandolapril was given to male Wistar rats with aortic banding at 10 AM or 10 PM for 6 weeks to examine the influence of dosing time on the development of left ventricular mass (LVM). Aortic banding increased the LVM compared with the sham-operated animals (P<0.01). Trandolapril (1 mg/kg) at 10 AM reduced LVM (1.74+/-0.04 [S.E.M.] mg/g) more than the dosing at 10 PM (1.92+/-0.04 mg/g, P<0.05), suggesting that trandolapril has a dosing time-dependent effect in the prevention of cardiac hypertrophy in rats with aortic banding.

Enhanced neutrophil superoxide anion production and its modification by beraprost sodium in spontaneously hypertensive rats

To clarify the function of polymorphonuclear leukocytes (PMN) in spontaneously hypertensive rats (SHR) and the effect of beraprost sodium (BS) on these functions, we examined superoxide anion (O2-) production and adherent activity by PMN, as well as modification of these functions by BS ex vivo and in vitro. In study 1, we measured PMN functions in 4-week-old SHR and Wistar-Kyoto (WKY) rats. In study 2 (ex vivo), 14-week-old SHR received vehicle (n = 6) and BS (30 microg/kg/day [n = 6] and 100 microg/kg/day [n = 7]) once daily for 4 weeks. In study 3 (in vitro), PMN from 18-week-old SHR were incubated with BS (0.1 and 1 micromol/L) and theophylline (200 micromol/L), which is reported to inhibit the PMN O2- production. Systolic blood pressure, platelet counts, and PMN O2- production stimulated by phorbol ester myristate acetate were significantly elevated in 4-week-old SHR compared with WKY (P < .05). Beraprost sodium decreased the ex vivo PMN O2- production, serum superoxide dismutase activity, and platelet counts (P < .05); however, BS did not reduce the in vitro PMN O2- production. These data support our hypothesis that the enhanced PMN function contributes to the cardiovascular damages during the early phase of SHR, and that BS has merit for preventing the O2- related organ damages in this model.

Furosemide-probenecid interaction as a laboratory exercise for undergraduate education in clinical pharmacology

OBJECTIVE

The aim of this study was to determine the easiness, reproducibility, and safety of a laboratory exercise for a drug interaction between furosemide and probenecid.

METHODS

From 1995 to 1999 approximately 100 medical students participated in the exercise each year after they gave written informed consent. The students were randomly assigned to one of the three groups in a double-blind fashion: group 1, placebo plus 20 mg of furosemide; group 2, 250 mg of probenecid plus 20 mg of furosemide; and group 3, 1000 mg of probenecid plus 20 mg of furosemide. The students took probenecid or its placebo 1 hour before furosemide. Urine volume and urinary sodium excretion were measured for 3 hours after furosemide. At the end of the exercise in 1999, students responded to several questionnaires concerning the utility of furosemide.

RESULTS

The entire course of the exercise was completed within half a day. The following findings were obtained every year. (1) Probenecid dose dependently blunted the diuretic effects of furosemide. (2) Time courses of the diuretic effects were altered by probenecid. Ten to twenty percent of the students had slight complaints but completed the exercise without any medications. Finally, more than 80% of the students considered the exercise to be useful.

CONCLUSIONS

The data suggest that the exercise of the drug interaction between furosemide and probenecid is easy to perform, reproducible, and safe. Through the experience of the laboratory exercise, students will develop an attitude to assess and estimate potential drug interactions before they prescribe drugs.

CyaG, a novel cyanobacterial adenylyl cyclase and a possible ancestor of mammalian guanylyl cyclases

A novel gene encoding an adenylyl cyclase, designated cyaG, was identified in the filamentous cyanobacterium Spirulina platensis. The predicted amino acid sequence of the C-terminal region of cyaG was similar to the catalytic domains of Class III adenylyl and guanylyl cyclases. The N-terminal region next to the catalytic domain of CyaG was similar to the dimerization domain, which is highly conserved among guanylyl cyclases. As a whole, CyaG is more closely related to guanylyl cyclases than to adenylyl cyclases in its primary structure. The catalytic domain of CyaG was expressed in Escherichia coli and partially purified. CyaG showed adenylyl cyclase (but not guanylyl cyclase) activity. By site-directed mutagenesis of three amino acid residues (Lys(533), Ile(603), and Asp(605)) within the purine ring recognition site of CyaG to Glu, Arg, and Cys, respectively, CyaG was transformed to a guanylyl cyclase that produced cGMP instead of cAMP. Thus having properties of both cyclases, CyaG may therefore represent a critical position in the evolution of Class III adenylyl and guanylyl cyclases.

Effect of angiotensin II on venodilator response to nitroglycerin

OBJECTIVE

An enhanced circulatory angiotensin II level that results from the administration of nitroglycerin may contribute to the development of nitrate tolerance. Using human hand veins, we investigated whether a subconstricting dose of angiotensin II attenuates the venodilator effect of nitroglycerin, whether pretreatment with losartan influences this effect, and whether angiotensin II also attenuates the venodilator effect of diltiazem.

METHODS

In 9 healthy male subjects, increasing doses (0.5-128 ng/min) of nitroglycerin were infused into the dorsal hand vein pretreated with 0 (control), 0.3, or 1 ng/min of angiotensin II. In 8 healthy male subjects, angiotensin II (0.3 and 1 ng/min) was infused into the vein dilated by nitroglycerin with and without pretreatment with losartan and with diltiazem. The diameter of the vein was measured with a linear variable differential transformer.

RESULTS

The venodilator response of nitroglycerin was significantly suppressed by the pretreatment with angiotensin II; The maximum venodilator effect was dose-dependently decreased, and the infusion rate producing half-maximum response was dose-dependently increased. The venodilation caused by nitroglycerin was decreased by angiotensin II, and this effect was attenuated by pretreatment with losartan. The venodilation caused by diltiazem was also attenuated by angiotensin II, but this attenuating effect was smaller compared with that caused by nitroglycerin.

CONCLUSIONS

These findings suggest that an enhanced angiotensin II level might attenuate the venodilation caused by nitroglycerin and diltiazem, and pretreatment with losartan might decrease the attenuating effect of angiotensin II.

Early stage gastric MALT lymphoma with high-grade component cured by Helicobacter pylori eradication

A 68-year-old woman was diagnosed with gastric lymphoma of the mucosa-associated lymphoid tissue (MALT) type with a high-grade component. Surgical treatment was recommended because of the presence of the high-grade component, but she refused surgery. As an alternative, she received Helicobacter pylori eradication treatment, which successfully induced regression of the lymphoma. She shows no sign of recurrence endoscopically and histologically, as of 29 months after the eradication treatment. Moreover, the B-cell monoclonality and Helicobacter pylori infection demonstrated at diagnosis has disappeared. This is one of the rare cases of gastric lymphoma of the MALT type with a high-grade component cured by Helicobacter pylori eradication alone.

Mutational analysis of genes involved in pilus structure, motility and transformation competency in the unicellular motile cyanobacterium Synechocystis sp. PCC 6803

The relevance of pilus-related genes to motility, pilus structure on the cell surface and competency of natural transformation was studied by gene disruption analysis in the unicellular motile cyanobacterium Synechocystis: sp. PCC 6803. The genes disrupted in this study were chosen as related to the pil genes for biogenesis of the type IV pili in a Gram-negative bacterium Pseudomonas aeruginosa. It was found that motility of Synechocystis cells was lost in the mutants of slr0063, slr1274, slr1275, slr1276, slr1277 and sll1694 together with a simultaneous loss of the thick pili on the cell surface. Competency of the natural transformation was lost in the mutants listed above and slr0197-disruptant. The gene slr0197 was previously predicted as a competence gene by a search with sequence-independent DNA-binding structure [Yura et al. (1999) DNA Res. 6: 75]. It was suggested that both DNA uptake for natural transformation and motility are mediated by a specific type IV-like pilus structure, while a putative DNA-binding protein encoded by slr0197 is additionally required for the DNA uptake. Based on the homology with the pil genes in P: aeruginosa, slr0063, slr1274, slr1275, slr1276, slr1277 and sll1694 were designated pilB1, pilM, pilN, pilO, pilQ and pilA1, respectively. The gene slr0197 was designated comA.

Pharmacokinetics and pharmacodynamics of temocapril during repeated dosing in elderly hypertensive patients

OBJECTIVE

To evaluate the pharmacokinetic profiles of temocaprilat and its hypotensive effect after single and repeated dosings of temocapril in young and elderly hypertensive patients.

METHODS

An angiotensin-converting enzyme inhibitor, temocapril (2 mg), was given once daily for 8 days to nine young and ten elderly hypertensive patients. Pharmacokinetics of temocaprilat, an active metabolite, and its hypotensive effect were evaluated after the first and last doses.

RESULTS

The area under the plasma concentration-time curve (AUC) of temocaprilat after the first dose was significantly greater in the elderly than in the young. This parameter was elevated after the final dose in both groups. The AUC (eighth dose)/AUC (first dose) ratio in the elderly was similar to that in the young. Blood pressure (BP) tended to decrease in the young and significantly decreased in the elderly after the first dose. The hypotensive effect was not enhanced after the final dose in either group.

CONCLUSION

These results suggest that although plasma temocaprilat concentration rises during repeated dosing, its BP-lowering effect is not enhanced in the elderly. Therefore, if a remarkable BP reduction is not detected at the initiation of treatment, the risk of hypotensive episode might be small during long-term therapy with temocapril in elderly hypertensive patients.

Pax-8 is essential for regulation of the thyroglobulin gene by transforming growth factor-beta1

Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine that is thought to play a major role in the regulation of growth and differentiation of thyroid cells. However, little is known of its detailed mechanisms of action in thyrocytes. We have therefore studied the molecular mechanisms of TGF-beta1 action on thyroglobulin (TG) gene expression by focusing our attention on TGF-beta1 regulation of thyroid-specific transcription factors. TGF-beta1 decreased TG messenger RNA (mRNA) expression both in the presence and in the absence of TSH in rat thyroid FRTL-5 cells. Transfected into FRTL-5 cells, the activity of reporter plasmids containing the rat TG promoter ligated to a luciferase gene was significantly suppressed by the addition of TGF-beta1. When the nuclear extracts prepared from TGF-beta1-treated FRTL-5 cells were used in gel mobility shift assays, the amount of protein-DNA complex formed by Pax-8 was reduced, both in the presence and in the absence of TSH, but protein-DNA complexes formed by thyroid transcription factor-1 (TTF-1) and TTF-2 were not. The suppressive effect of TGF-beta1 on Pax-8/DNA complex formation is in part due to the suppression of Pax-8 mRNA and protein levels by TGF-beta1. Expressions of Pax-8 mRNA and protein, which were assessed by Northern blot and Western blot analyses, respectively, were decreased by TGF-beta1 treatment of FRTL-5 cells in a concentration-dependent manner. In a transfection experiment, mutation of the Pax-8-binding site caused a loss of both TGF-beta1- and TSH-responsiveness in TG promoter activity. Overexpression of Pax-8 abolished the TGF-beta1 suppression of TG promoter activity. These results indicate that TGF-beta1 decreases Pax-8 mRNA levels as well as Pax-8 DNA-binding activity, which, at least in part, seems to be involved in the TGF-beta1-induced suppression of TG gene expression.

Sarcomatoid hepatocellular carcinoma with chondroid variant: case report with immunohistochemical findings

A case of sarcomatoid hepatocellular carcinoma (HCC) with a chondroid variant in a 72-year-old woman is reported. Histologically, the tumor consisted of typical HCC of adult type, with an adenocarcinoma-like structure and a sarcomatoid component containing multinodular chondroid foci. Transition from carcinoma to sarcomatoid component was observed. The cells containing mucus were extremely few in adenocarcinoma-like structures. Immunohistochemically, other than typical HCC, some of the chondroid cells, adenocarcinoma-like cells and sarcomatoid cells were positive for alpha-fetoprotein.

Intrathyroidal branchial cleft-like cyst in chronic thyroiditis

An extremely rare case of intrathyroidal branchial cleft-like cyst is reported. A 71-year-old man complained of a growing mass in the right lateral neck. A cystic mass in the upper lobe of the right thyroid was demonstrated by ultrasonography and computed tomography. The surgical specimen revealed a cystic mass with dense fibrous capsule, 22 x 20 x 10 mm in size. Microscopically, the cyst walls and the surrounding thyroid tissue contained severe lymphoid cell infiltration with lymphoid follicle. Squamous epithelium lined the cyst wall. Immunohistochemically, squamous epithelium was positive for keratin, cytokeratin 19, carcinoembryonic antigen, and epithelial membrane antigen, but negative for calcitonin and chromogranin A. The patient is currently well with no evidence or recurrence for 43 months.

Urinary metabolites of gallic acid in rats and their radical-scavenging effects on 1,1-diphenyl-2-picrylhydrazyl radical

As a part of our studies on the metabolism of natural compounds, gallic acid was orally administered to rats. The urinary metabolites were analyzed by high-performance liquid chromatography, and their structures were determined to be pyrogallol (M1), pyrogallol-1-O-beta-D-glucuronide (M2), 4-O-methylgallic acid-3-O-sulfate (M3), 2-O-methylpyrogallol-1-O-beta-D-glucuronide (M4), 2-O-methylpyrogallol (M5), 4-O-methylgallic acid (M6), and unchanged gallic acid on the basis of chemical and spectral data. The radical scavenging effects of gallic acid and its urinary metabolites were evaluated using 1,1-diphenyl-2-picrylhydrazyl radical.

The effect of a Rho kinase inhibitor Y-27632 on superoxide production, aggregation and adhesion in human polymorphonuclear leukocytes

We investigated the involvement of p160ROCK (a Rho-associated coiled coil-forming protein kinase), one of Rho kinases on superoxide anion production (O(2)(-) production), aggregation and adhesion of human polymorphonuclear leukocytes under physiological condition, using a selective p160ROCK inhibitor, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide (Y-27632). Y-27632 inhibited the O(2)(-) production stimulated by phorbol-12-myristate-13-acetate (PMA) in a dose-dependent manner. Stauroprorine blocked the PMA-induced O(2)(-) production while wortmannin did not. Y-27632 also inhibited the O(2)(-) production by guanosine 5'-O-(3-thiotriphosphate) (GTP(gamma)S) 100 microM. N-formyl-Met-Leu-Phe (fMLP)-induced O(2)(-) production was not influenced by Y-27632, but was inhibited by wortmannin. The enhanced O(2)(-) production by Ca-ionophore A23817 and thapsigargin was not inhibited by Y-27632. Y-27632 did not change the basal intracellular Ca(2+) concentration nor its elevation stimulated by fMLP. Polymorphonuclear leukocytes aggregation induced by PMA was dose-dependently decreased by Y-27632 while their aggregation stimulated by fMLP was enhanced by the agent. Polymorphonuclear leukocytes adhesion induced by PMA or fMLP was not influenced by Y-27632.These results suggest that p160ROCK is involved in the PMA-induced O(2)(-) production and aggregation in human polymorphonuclear leukocytes. This kinase might locate in downstream of protein kinase C in polymorphonuclear leukocytes.

CD138-positive and Kaposi's sarcoma-associated herpesvirus (KSHV)-negative B-cell lymphoma with serosal spreading of the body cavity and lymphadenopathy: an autopsy case

CD138-positive and Kaposi's sarcoma-associated herpes virus (KSHV)-negative B cell lymphoma with serosal spreading of the body cavity and lymphadenopathy is presented. Our lymphoma cells showed pleomorphic morphology and a clonal immunoglobulin gene rearrangement. Immunophenotypically, they lacked B- and T-cell-associated antigens but expressed strong membranous CD138 antigen along the serosa. Although our case was not conventional primary effusion lymphoma (PEL) because of the absence of KSHV and the presence of lymphadenopathy, its unique phenotype and serosal spreading were consistent with those of PEL. Our case suggests that, irrespective of KSHV infection, some pleomorphic B cell lymphomas with membranous CD138 expression show a peculiar serosal spreading.

Influence of losartan on alpha-adrenoceptor-mediated vasoconstrictor response in humans

To evaluate the influence of losartan on alpha-adrenoceptor-mediated vasoconstrictor response, we examined dorsal hand vein constrictor response to phenylephrine (16-8,192 ng/min) and fingertip vasoconstrictor response to cold stimulation with and without pretreatment with losartan (50 mg/day) for 3 days in nine healthy men. The effect of coadministration of angiotensin II (Ang II) (0.3 ng/min) on the venoconstrictor response also was evaluated. Oral pretreatment with losartan alone influenced neither of the responses. The log of the infusion rate of phenylephrine producing half-maximal venoconstriction [log(ED50)] was 2.69 +/- 0.10 (mean +/- SEM) for control and 2.68 +/- 0.09 for losartan, and the reduction ratio of fingertip blood flow was 68.1 +/- 4.0% for control and 66.7 +/- 4.3% for losartan. Coadministration of Ang II, however, significantly enhanced the venoconstrictor response to phenylephrine [log(ED50): 2.43 +/- 0.09, p < 0.05 vs. control], and the pretreatment with losartan attenuated this effect [log(ED50): 2.60 +/- 0.11]. These findings indicate that the alpha-adrenoceptor-mediated vasoconstrictor response is not influenced by losartan; however, it is enhanced by exogenous Ang II, and losartan attenuates the enhanced response, in healthy human subjects.

Polymorphonuclear leukocytes (PMNs) functions in SHR, L-NAME- and DOCA/salt-induced hypertensive rats

OBJECTIVES

To clarify ex-vivo polymorphonuclear leukocytes (PMNs) functions, we examined superoxide anion (O2-) production and adhesion to a plastic plate of isolated PMNs obtained from spontaneously hypertensive rats (SHR/lzm), NG-nitro-L-arginine methyl ester (L-NAME)- and deoxycorticosterone acetate (DOCA)/salt-induced hypertensive rats.

DESIGN

Sixteen week-old male SHR/Izm and Wistar-Kyoto rats (WKY/Izm) were used as a model of hypertension and its control, respectively. L-NAME-hypertension was induced by oral administration of 100 mg/kg per day of L-NAME twice daily for 4 weeks using 4-week-old male Wistar rats. DOCA/salt-hypertension was induced by once daily subcutaneous injection of 1 mg DOCA with 1% NaCl drinking water for 2 weeks using 8-week-old male Wistar rats with heminephrectomy.

METHODS

Heparinized whole blood was obtained from abdominal aorta. PMNs were isolated by density gradient following dextran sedimentation. A production of superoxide anion (O2-) by PMNs stimulated with phorbol ester myristate acetate (PMA, 100 ng/ml) was determined by a superoxide dismutase (SOD)-inhibitable cytochrome-C reduction method. Adhesion of PMNs was evaluated by their protein content on a plastic plate measured by Lowry method.

RESULTS

SHR/Izm showed a significant enhancement of O2- production by isolated PMNs compared with WKY/Izm. Rats treated with L-NAME showed a lower O2- production by PMNs compared to control animals. In DOCA/salt hypertensive rats, O2- production was not different from that in the control rats. Adherent function of isolated PMNs did not differ significantly among these hypertensive animal models.

CONCLUSIONS

These results suggest that O2- production by circulatory PMNs is augmented in SHR, but not in L-NAME and DOCA/salt hypertensive rats. This enhanced function, which is also observed in human essential hypertension, might contribute to the development of cardiovascular damage in genetically determined hypertension.