Collective cell migration over long time scales reveals distinct phenotypes

Introduction

Migratory phenotypes of metastasizing tumor cells include single and collective cell migration. While migration of tumor cells is generally less cooperative than that of normal epithelial cells, our understanding of precisely how they differ in long time behavior is incomplete.

Objectives

We measure in a model system how cancer progression affects collective migration on long time scales, and determine how perturbation of cell-cell adhesions, specifically reduced E-cadherin expression, affects the collective migration phenotype.

Methods

Time lapse imaging of cellular sheets and particle image velocimetry (PIV) are used to quantitatively study the dynamics of cell motion over ten hours. Long time dynamics are measured via finite time Lyapunov exponents (FTLE) and changes in FTLE with time.

Results

We find that non-malignant MCF10A cells are distinguished from malignant MCF10CA1a cells by both their short time (minutes) and long time (hours) dynamics. In addition, short time dynamics distinguish non-malignant E-cadherin knockdown cells from the control, but long time dynamics and increasing spatial correlations remain unchanged.

Discussion

Epithelial sheet collective behavior includes long time dynamics that cannot be captured by metrics that assess cooperativity based on short time dynamics, such as instantaneous speed or directionality. The use of metrics incorporating migration data over hours instead of minutes allows us to more precisely describe how E-cadherin, a clinically relevant adhesion molecule, affects collective migration. We predict that the long time scale metrics described here will be more robust and predictive of malignant behavior than analysis of instantaneous velocity fields alone.

[Identification of a Novel Calcium (Ca^(2+))-Activated Chloride Channel Accessory Gene in Xenopus laevis]

Calcium (Ca^(2+))-activated chloride channel accessories (CLCAs) are putative anion channel-related proteins with diverse physiological functions. Exploring CLCA diversity is important for prediction of gene structure and function. In an effort to identify novel CLCA genes in Xenopus laevis, we successfully cloned and characterized a Xenopus laevis cDNA predicted to encode the xCLCA3 gene. Cloning of xCLCA3 was achieved by computational analysis, rapid amplification of cDNA ends (RACE), and a tissue distribution analysis by semi-quantitative reverse transcription (RT) PCR or real-time PCR. We obtained a 2958 bp xCLCA3 cDNA sequence with an open reading frame encoding 943 amino acids. According to the primary structure analysis, xCLCA3 contains a predicted signal sequence, multiple sites of N-linked (N-) glycosylation, N-myristoylation, PKA, PKC, and casein kinase II phosphorylation sites, five putative hydrophobic segments, and the HExxH metalloprotease motif. Additionally, the transmembrane prediction server yielded a preserved N-terminal CLCA domain and a von Willebrand factor type A domain with one transmembrane domain in the C-terminal region. Expression analysis showed that xCLCA3 is expressed in a number of tissues, with strong expression in the brain, colon, small intestine, lung, kidney, and spleen, and poor expression in the heart and liver. These results suggest that xCLCA3 may be a candidate CLCA family member as well as a metalloprotease, rather than just an ion channel accessory protein.

Eat Right-Live Well! Supermarket Intervention Impact on Sales of Healthy Foods in a Low-Income Neighborhood

OBJECTIVE

To evaluate a multifaceted supermarket intervention promoting healthier alternatives to commonly purchased foods.

DESIGN

Sales of 385 foods promoted between July and October, 2012 in the Eat Right-Live Well! intervention supermarket were compared with sales in a control supermarket.

SETTING

Two supermarkets in geographically separate, low-income, urban neighborhoods.

PARTICIPANTS

One control and 1 intervention supermarket.

INTERVENTION

Product labeling, employee training, community outreach, and in-store promotions, including taste tests.

MAIN OUTCOME MEASURES

Number of items sold; absolute and percent differences in sales.

ANALYSIS

Difference-in-difference analyses compared absolute and percent changes between stores and over time within stores. Sub-analyses examined taste-tested items and specific food categories, and promoted items labeled with high fidelity.

RESULTS

Comparing pre- and postintervention periods, within-store difference-in-differences for promoted products in the intervention store (25,776 items; 23.1%) was more favorable than the control (9,429 items; 6.6%). The decrease in taste-tested items' sales was smaller in the intervention store (946 items; 5.5%) than the control store (14,666 items; 26.6%). Increased sales of foods labeled with high fidelity were greater in the intervention store (25,414 items; 28.0%) than the control store (7,306 items; 6.3%).

CONCLUSIONS AND IMPLICATIONS

Store-based interventions, particularly high-fidelity labeling, can increase promoted food sales.

Process Evaluation of a Comprehensive Supermarket Intervention in a Low-Income Baltimore Community

Supermarket-based interventions are one approach to improving the local food environment and reducing obesity and chronic disease in low-income populations. We implemented a multicomponent intervention that aimed to reduce environmental barriers to healthy food purchasing in a supermarket in Southwest Baltimore. The intervention, Eat Right-Live Well! used: shelf labels and in-store displays promoting healthy foods, sales and promotions on healthy foods, in-store taste tests, increasing healthy food products, community outreach events to promote the intervention, and employee training. We evaluated program implementation through store environment, taste test session, and community event evaluation forms as well as an Employee Impact Questionnaire. The stocking, labeling, and advertising of promoted foods were implemented with high and moderate fidelity. Taste test sessions were implemented with moderate reach and low dose. Community outreach events were implemented with high reach and dose. Supermarket employee training had no significant impact on employees' knowledge, self-efficacy, or behavioral intention for helping customers with healthy purchasing or related topics of nutrition and food safety. In summary, components of this intervention to promote healthy eating were implemented with varying success within a large supermarket. Greater participation from management and employees could improve implementation.

Offshore finfish aquaculture in the United States: An examination of federal laws that could be used to address environmental and occupational public health risks

Half of the world’s edible seafood comes from aquaculture, and the United States (US) government is working to develop an offshore finfish aquaculture industry in federal waters. To date, US aquaculture has largely been regulated at the state level, and creating an offshore aquaculture industry will require the development of a new regulatory structure. Some aquaculture practices involve hazardous working conditions and the use of veterinary drugs, agrochemicals, and questionable farming methods, which could raise environmental and occupational public health concerns if these methods are employed in the offshore finfish industry in the US. This policy analysis aims to inform public health professionals and other stakeholders in the policy debate regarding how offshore finfish aquaculture should be regulated in the US to protect human health; previous policy analyses on this topic have focused on environmental impacts. We identified 20 federal laws related to offshore finfish aquaculture, including 11 that are relevant to preventing, controlling, or monitoring potential public health risks. Given the novelty of the industry in the US, myriad relevant laws, and jurisdictional issues in an offshore setting, federal agencies need to work collaboratively and transparently to ensure that a comprehensive and functional regulatory structure is established that addresses the potential public health risks associated with this type of food production.

Stilbene 5c, a microtubule poison with vascular disrupting properties that induces multiple modes of growth arrest and cell death

The stilbene derivative, cis-3,4',5-trimethoxy-3'-aminostilbene (stilbene 5c), is a potentially potent antitumor agent that acts via binding to the colchicine-binding site in tubulin. The current studies were designed to investigate the effectiveness of stilbene 5c against the HCT-116 human colon cancer cell line and B16/F10 melanoma cells as well as human endothelial cell tube formation and tumor perfusion. Stilbene 5c produced a time-dependent decrease in cell viability in both cell lines and the capacity of the cells to proliferate was not restored upon removal of the drug. Treatment with stilbene 5c also promoted both senescence and autophagy in both cell lines. TUNEL and annexin 5 staining indicated that apoptosis also occurs in stilbene 5c-treated HCT-116 cells, but not in B16/F10 melanoma cells. DAPI staining revealed morphological changes in the cell nuclei (binucleated and micronucleated cells) indicative of mitotic catastrophe in HCT-116 cells but not in the B16/F10 melanoma cells. p53-null HCT-116 cells demonstrated a similar growth arrest/cell death response to stilbene as p53-wild type HCT-116 cells. Stilbene 5c also completely inhibited human endothelial cell tube formation on Matrigel, consistent with potential anti-angiogenic actions. Using a new method developed for monitoring the pharmacodynamic effects of stilbene 5c in vivo, we found that a single injection of stilbene 5c reduced tumor perfusion by 65% at 4h, returning to baseline by 24h, while subsequent daily injections of stilbene 5c produced progressively larger reductions and smaller rebounds. This work indicates that stilbene 5c could potentially be effective against melanoma and colon cancer through the promotion of multiple modes of growth arrest and cell death coupled with anti-angiogenic and antivascular actions.

Cyclic vomiting syndrome and functional vomiting in adults: association with cannabinoid use in males

BACKGROUND

Cyclic vomiting syndrome (CVS) is characterized by stereotypical episodes of vomiting separated by symptom-free intervals. However, the difficulty encountered in the management of patients with CVS may be a reflection of a deficiency in our understanding of the disorder. We aimed to evaluate whether clinical or gastric emptying (GE) data discriminate patients labeled as having CVS from functional vomiting (FV) or irritable bowel syndrome (IBS).

METHODS

The medical records of patients diagnosed with any vomiting (including CVS, FV) over a 13-year period (1993-2006) at our institution were carefully reviewed. Disease controls were age and gender matched subjects with IBS. Gastric emptying was performed by scintigraphy (99mTc-egg meal). The associations of clinical factors and GE data with patient status (CVS vs FV or IBS) were analyzed.

KEY RESULTS

A total of 82 patients with CVS and 62 FV patients were identified. Younger age [per 10 years, OR = 0.7 (0.5, 0.9)], male gender [OR = 0.4 (0.2, 0.9)], and cannabinoid use [OR = 2.9 (1.2, 7.2)] were significantly associated with CVS compared with FV. However, there were no significant associations between patient status (CVS vs FV) and age, BMI, smoking, alcohol use, gastrointestinal symptoms, or GE. The proportion of cannabinoid users was significantly higher in patients with CVS compared with patients with IBS, whereas proportions for headaches and psychiatric disease were higher in subjects with IBS.

CONCLUSIONS & INFERENCES

Cyclic vomiting syndrome (vs FV) was not associated with clinical factors, but was associated with younger age, male gender and cannabinoid use. A larger proportion of CVS (vs IBS) patients had used cannabinoids.

Strategies for improving the efficiency of quantum Monte Carlo calculations

We describe a number of strategies for minimizing and calculating accurately the statistical uncertainty in quantum Monte Carlo calculations. We investigate the impact of the sampling algorithm on the efficiency of the variational Monte Carlo method. We then propose a technique to maximize the efficiency of the linear extrapolation of diffusion Monte Carlo results to zero time step, finding that a relative time-step ratio of 1:4 is optimal. Finally, we discuss the removal of serial correlation from data sets by reblocking, setting out criteria for the choice of block length and quantifying the effects of the uncertainty in the estimated correlation length.

Malignant peripheral nerve sheath tumor mimicking carotid body tumor--case report and review

Malignant peripheral nerve sheath tumor is a rare neurogenic tumor that usually presents in geriatic patients. Typically, it is found in the trunk and extremities and rarely presents in the head and neck region. It may mimic a carotid body tumor when it presents in the neck. We report the first case of malignant peripheral nerve sheath tumor of the vagus nerve in an adolescent boy. He presented with an asymptomatic lateral neck lump that was thought to be a benign schwannoma on preoperative imaging. We describe the diagnostic dilemma and management difficulties in this patient and review the literature.

Biochemical and structural consequences of a glycine deletion in the alpha-8 helix of protoporphyrinogen oxidase

A rare Gly210 deletion in protoporphyrinogen oxidase (PPO) was recently discovered in herbicide-resistant Amaranthus tuberculatus. According to the published X-ray structure of Nicotiana tabacum PPO, Gly210 is adjacent to, not in, the PPO active site, so it is a matter of interest to determine why its deletion imparts resistance to herbicides. In our kinetic experiments, this deletion did not affect the affinity of protoporphyrinogen IX nor the FAD content, but decreased the catalytic efficiency of the enzyme. The suboptimal Kcat was compensated by a significant increase in the Kis for inhibitors and a switch in their interactions from competitive to mixed-type inhibition. In our protein modeling studies on herbicide-susceptible PPO and resistant PPO, we show that Gly210 plays a key role in the alphaL helix-capping motif at the C-terminus of the alpha-8 helix which helps to stabilize the helix. In molecular dynamics simulations, the deletion had significant architecture consequences, destabilizing the alpha-8 helix-capping region and unraveling the last turn of the helix, leading to enlargement of the active site cavity by approximately 50%. This seemingly innocuous deletion of Gly210 of the mitochondrial PPO imparts herbicide resistance to this dual-targeted protein without severely affecting its normal physiological function, which may explain why this unusual mutation was the favored evolutionary path for achieving resistance to PPO inhibitors.

Induction of melanoma cell apoptosis and inhibition of tumor growth using a cell-permeable Survivin antagonist

The inhibitor of apoptosis gene family member Survivin is highly expressed in most tumors, and appears to be a promising target for cancer therapy. Although a variety of Survivin antagonists have been shown to induce apoptosis in malignant cells, the potential utility of these agents is limited by inefficient delivery and cell impermeability. We generated recombinant fusion proteins containing the TAT protein transduction domain and either wild-type Survivin (TAT-Surv-WT) or a dominant-negative mutant (TAT-Surv-T34A). The TAT-Surv proteins were purified by sequential affinity and ion-exchange chromatography, and at 30 nM concentration demonstrated rapid entry into cells at 30 min. Whereas TAT-Surv-WT had minimal effect on YUSAC2 or WM793 melanoma cells, TAT-Surv-T34A induced cell detachment, DNA fragmentation, caspase-3 activation and mitochondrial release of apoptosis-inducing factor at low microM concentrations. Intraperitoneal (i.p.) injection of mice bearing subcutaneous YUSAC2 xenografts with TAT-Surv-T34A (10 mg/kg) was associated with rapid tumor accumulation at 1 h, and increased tumor cell apoptosis and aberrant nuclei formation in situ. Repeated i.p. injection of TAT-Surv-T34A resulted in a 40-50% reduction in growth and mass of established tumors, compared to those similarly injected with saline buffer or TAT-Surv-WT. These studies demonstrate the feasibility of systemic tumor treatment using a cell-permeable Survivin antagonist.

Influenza A Viruses Upregulate Neutrophil Toll-Like Receptor 2 Expression and Function

Neutrophils are involved in the initial host response to influenza A virus (IAV) infection and exhibit both activation and depressed function after exposure to the virus. We demonstrate that IAV causes rapid upregulation of Toll-like receptor 2 (TLR2) expression on neutrophils. The neutrophil agonists, formyl-methylpleucyl-alanine (fMLP), C5a and lipopolysaccharide did not alter neutrophil TLR2 expression, whereas PMA and the microbial TLR2 ligands, peptidoglycan (PGN) and zymosan, reduced it. To determine the functional significance of IAV-induced increase in TLR2 expression, IAV-treated neutrophils were exposed to PGN, Staphylococcus aureus (S. aureus) and zymosan. Pretreatment with IAV resulted in significantly increased uptake of S. aureus and zymosan and accelerated neutrophil apoptosis when combined with S. aureus. IAV-treated cells generated significantly more H(2)O(2) in response to PGN. These results indicate that IAV increases neutrophil surface expression of TLR2 and modulates functional responses to ligands that bind TLR2. These findings may clarify IAV-induced perturbation of neutrophil functions in vivo.

The cardiolipin-binding domain of Bid affects mitochondrial respiration and enhances cytochrome c release

Bid is cleaved by caspase 8 during apoptosis and the truncated Bid (tBid) translocates to mitochondria by targeting cardiolipin. Amino acids 103-162 of Bid were reported as the cardiolipin-binding domain (CBD). The EGFP-CBD fusion protein targets to mitochondria and induces apoptosis. Using [(3)H]cardiolipin, we proved that recombinant CBD binds cardiolipin similar to tBid and tBid(G94E), a mutant with a defective BH3 domain. CBD could induce cytochrome c release from isolated mitochondria, but much less potent than tBid. Free cardiolipin inhibited the CBD-induced cytochrome c release, suggesting that it may be mediated by interfering with mitochondrial cardiolipin, especially with the interaction between cytochrome c and cardiolipin. This is consistent with the findings that CBD induced cytochrome c release in Bax-deficient cells, and that CBD suppressed mitochondrial respiration through directly interfering with cardiolipin, a critical lipid involved in oxidative phosphorylation. These results indicate the functional importance of CBD in tBid-induced apoptosis.

Patterns of Catholic-Protestant intermarriage in Northern Ireland

"Some of the social factors governing the incidence of religious intermarriage in Northern Ireland are reviewed before setting out data from a special tabulation of the 1971 census of Northern Ireland. According to the tabulation only some 2% of married couples enumerated declared themselves to be in Catholic-Protestant marriages....The tabulation suggests that the likelihood of marriage across the Catholic-Protestant divide is no greater for manual workers than for nonmanual workers when controls are introduced for relative group size.... There are indications that the incidence of Catholic-Protestant marriage was rising in Northern Ireland in the late 1960s."

Controversial and special situations in the management of preterm premature rupture of membranes

The management of preterm premature rupture of membranes is one of the many controversial areas of medicine. Many of the protocols used to manage preterm premature rupture of membranes are not based on solid data. Other situations are rarely encountered, making it very difficult to arrive at a management scheme on which all can agree. This article presents five such areas along with available literature and discusses treatment options involving these controversial or special topics.

Immunoglobulin A anti-beta2-glycoprotein antibodies in women who experience unexplained recurrent spontaneous abortion and unexplained fetal death

OBJECTIVE

Studies in rheumatologic populations suggest that immunoglobulin A antiphospholipid antibodies are strongly associated with the clinical manifestations of antiphospholipid syndrome. However, the association between immunoglobulin A antiphospholipid antibodies and pregnancy loss is uncertain. We determined whether immunoglobulin A antiphospholipid antibodies, specifically anti-beta(2)-glycoprotein I and anticardiolipin, are associated with the obstetric features of antiphospholipid syndrome.

STUDY DESIGN

Sera from 4 groups of women were studied: (1) 133 women who experienced unexplained recurrent spontaneous abortion, (2) 48 women who experienced unexplained fetal death, (3) 145 healthy fertile control subjects, and (4) 67 women with well-characterized antiphospholipid syndrome. Serum immunoglobulin A, immunoglobulin G, and immunoglobulin M anti-beta(2)-glycoprotein I and anticardiolipin antibodies were determined by enzyme-linked immunoassay.

RESULTS

Groups of women who experienced unexplained recurrent spontaneous abortion and unexplained fetal death had a higher proportion of women who had positive test results for immunoglobulin A anti-beta(2)-glycoprotein I antibodies than fertile control subjects (P < .01, chi-square test); these subjects also had higher levels of autoantibody (P = .001, Kruskal-Wallis). Women who experienced recurrent spontaneous abortion had a higher proportion of women with positive test results for immunoglobulin A anticardiolipin antibodies compared to fertile control subjects (P < .05, chi-square test); this group also had higher levels of autoantibody (P = .0065, Kruskal-Wallis test). Linear regression analysis showed significant correlation between anti-beta(2)-glycoprotein I immunoglobulin A and anti-beta(2)-glycoprotein I immunoglobulin G (R = .609; P =.0001) and less correlation between anticardiolipin immunoglobulin A and anticardiolipin immunoglobulin G (R = .093; P = .065).

CONCLUSION

Immunoglobulin A anti-beta(2)-glycoprotein I antibodies are more common in women who experience unexplained recurrent spontaneous abortion and unexplained fetal death whose initial test results are negative for lupus anticoagulant and immunoglobulin G anticardiolipin antibodies compared to fertile control subjects. Therefore, these antibodies may identify additional women with clinical features of antiphospholipid syndrome who are not identified through traditional testing. It is unclear whether these antibodies are directly pathogenic, a result of the pregnancy losses, or markers for an underlying, yet uncharacterized autoimmune disorder.

The Korean diasporic experience: measuring ethnic identity in the United States and China

The measurement and development of ethnic identity of Koreans living in the United States and China were examined in the context of different migration experiences. Three hundred sixteen undergraduate college students were administered the Multigroup Ethnic Identity Measure (MEIM; J. S. Phinney, 1992). Separate principal-component analysis for each sample was performed to create cross-culturally equivalent Ethnic Identity and Other-Group subscales. Differential item function analysis revealed no cultural item bias among the retained MEIM items. Korean Americans had higher scores on the Ethnic Identity and Other-Group subscales and were more likely to be classified as bicultural than were Korean Chinese. Korean Chinese were more likely to be classified as assimilated, traditional, or marginalized in their cultural orientation.

Heparin-induced thrombocytopenia is rare in pregnancy

OBJECTIVE

The indications for heparin use during pregnancy are expanding; however, heparin is associated with serious adverse effects including heparin-induced thrombocytopenia. Low-molecular-weight heparin is expensive but is associated with less frequent occurrences of heparin-induced thrombocytopenia in the nonpregnant population. However, the incidence of heparin-induced thrombocytopenia during pregnancy is unknown. The purpose of this study was to compare the incidence of heparin-induced thrombocytopenia in pregnant and nonpregnant women.

STUDY DESIGN

This is a retrospective cohort comparison. Pregnant and nonpregnant women were identified by means of diagnosis related group and Current Procedural Terminology code searches at three medical centers in Utah; the incidence of heparin-induced thrombocytopenia in the two groups was compared.

RESULTS

There were 10 (4%) cases of thrombocytopenia among 244 heparin-treated pregnant patients and 26 (11%) cases among the 244 nonpregnant controls. There were no cases of heparin-induced thrombocytopenia in the pregnant group, but there were 10 (4%) cases in the control group (P =.0014).

CONCLUSION

Heparin-induced thrombocytopenia is extremely rare in pregnant women.

Abnormal renal medullary response to angiotensin II in SHR is corrected by long-term enalapril treatment

This study tested the hypotheses that renal medullary blood flow (MBF) in spontaneously hypertensive rats (SHR) has enhanced responsiveness to angiotensin (ANG) II and that long-term treatment with enalapril can correct this. MBF, measured by laser Doppler flowmetry in anesthetized rats, was not altered significantly by ANG II in Wistar-Kyoto (WKY) rats, but was reduced dose dependently (25% at 50 ng. kg(-1). min(-1)) in SHR. Infusion of N(G)-nitro-L-arginine methyl ester (L-NAME) into the renal medulla unmasked ANG II sensitivity in WKY rats while L-arginine given into the renal medulla abolished the responses to ANG II in SHR. In 18- to 19-wk-old SHR treated with enalapril (25 mg. kg(-1). day(-1) when 4 to 14 wk old), ANG II did not alter MBF significantly, but sensitivity to ANG II was unmasked after L-NAME was infused into the renal medulla. Endothelium-dependent vasodilation (assessed with aortic rings) was significantly greater in treated SHR when compared with that in control SHR. These results indicate that MBF in SHR is sensitive to low-dose ANG II and suggest that this effect may be due to an impaired counterregulatory effect of nitric oxide. Long-term treatment with enalapril improves endothelium-dependent vascular relaxation and decreases the sensitivity of MBF to ANG II. These effects may be causally related to the persistent antihypertensive action of enalapril in SHR.

Increased medial smooth muscle cell length is responsible for vascular hypertrophy in young hypertensive rats

Large mesenteric arteries from 3- to 4-wk-old spontaneously hypertensive rats (SHR) showed medial hypertrophy and an increased contractile response to various agonists before significant blood pressure increase. Here we determined the cellular nature of this vascular hypertrophy. Large mesenteric arteries from SHR and Wistar-Kyoto (WKY) rats were fixed at maximal relaxation either with an in situ perfusion fixation or an in vitro fixation method. With the use of morphometric protocols and confocal microscopy, the volume of the medial wall and lumen, numerical density of smooth muscle cell nuclei in the medial layer, and smooth muscle cell and nuclear length were measured. Both methods of fixation yielded similar results, showing significant medial volume expansion in SHR than WKY without lumen change. Numerical density of medial smooth muscle cells was significantly less in SHR than WKY, and their total number per 100 microm length were similar between the strains. Average smooth muscle nuclear and cell length from SHR was significantly longer than that of WKY. Regression analysis showed that the increase in smooth muscle cell length explained 80% of the medial volume increase. We concluded that increased smooth muscle cell length in prehypertensive SHR is responsible for increased medial volume in the mesenteric arteries.

Effects of hydrogen peroxide on pig coronary artery endothelium

Peroxides and other reactive oxygen species damage arteries during ischemia-reperfusion. Here, we report on the effects of H(2)O(2) on contractility of pig coronary artery. We either treated 3-mm coronary artery rings with 0 to 0.5 mM H(2)O(2) in organ baths or we perfused the arteries with H(2)O(2) and then cut them into rings. In each instance, we monitored the force of contraction of 3-mm rings in H(2)O(2)-free solution with 30 mM KCl and then we determined the A23187 induced endothelium dependent relaxation as a percent of this contraction. Treatment with H(2)O(2) in the organ bath caused a decrease in the contraction but it did not affect the percent relaxation. Treating arteries with H(2)O(2) by luminal perfusion did not affect the contraction but it decreased the percent relaxation. Perfusion alone decreased the amount of endothelium remaining in the arteries and perfusing with H(2)O(2) decreased it further. The percent relaxation with A23187 correlated well with the endothelium remaining in the arteries. We propose that H(2)O(2) and shear stress can cause a loss of endothelium and that endothelium can also protect the underlying smooth muscle against luminal H(2)O(2).

Nifedipine induces apoptosis in cultured vascular smooth muscle cells from spontaneously hypertensive rats

Apoptosis (programmed cell death) of smooth muscle cells (SMC) in blood vessels is an essential process involved in the control of vessel wall structure. Several antihypertensive drugs currently used in therapy may exert their pharmacological effects by promoting SMC apoptosis. The biochemical events which regulate SMC apoptosis in the vessel wall are complex, and not well understood. We therefore investigated whether treatment of cultured SMC from normotensive Wistar-Kyoto rats (WKY) and from spontaneously hypertensive rats (SHR) with selected antihypertensive drugs would induce SMC apoptosis. We treated aortic SMC from WKY and SHR in vitro with the L-type Ca2+ channel antagonist, nifedipine; with the nitric oxide donor, sodium nitroprusside (SNAP); with forskolin (an activator of adenylyl cyclase); or with thapsigargin (a selective inhibitor of the sarcoplasmic reticulum (SR), Ca2+-ATPase); and compared their apoptosis-promoting effects in SMC derived from the two strains of rats. SMC were derived from the thoracic aorta of 3-4-week-old WKY and SHR, and were used in passages 7-10. Apoptotic cells were detected by in-situ end labeling using the terminal deoxynucleotide transferase-mediated dUTP-nick end-labeling (TUNEL) method, and by morphological examination. We found that: 1) Treatment of cultured aortic SMC with the L-type Ca2+ channel antagonist, nifedipine (5 X 10(-5) M) for 24 hours induced a significantly higher level of apoptosis in SHR cells than in SMC from WKY. Cells from WKY, following exposure to nifedipine for 72 hours, exhibited a similar response to the cells from SHR treated for 24 hours. This was detectable by both morphological criteria as well as DNA labeling by the TUNEL technique. 2) Similar treatment of these cells with thapsigargin (1 x 10(-7) M) led to morphological alterations characteristic of apoptotic cells in SMC from both WKY and SHR, and cells from SHR but not WKY were labeled by the TUNEL technique at 24 hours. The TUNEL method did however identify cells from both WKY and SHR as apoptotic after 48 and 72 hours of treatment. 3) The addition of SNAP, or forskolin to the cultured SMC induced significant, but low levels of apoptosis in WKY SMC only. This selective apoptosis-promoting effect of nifedipine in SHR SMC may result from differences in the control of intracellular Ca2+ between the two strains of cells, or it may indicate that the signaling pathways which regulate apoptosis are different in SMC from the normotensive and the hypertensive rats. Our findings imply that SMC apoptosis may be a selective target for pharmacological intervention in hypertension.

Vascular beta-adrenoceptor function in hypertension and in ageing

Functional beta-adrenoceptors (beta-AR) have been identified and characterized in blood vessels under in vivo conditions as well as in vascular smooth muscle cells (SMC) grown in culture. Agonist occupancy of beta-AR activates adenylyl cyclase (AC) via the stimulatory guanine nucleotide-binding protein (Gs) and leads to elevations in intracellular adenosine 3'5'-cyclic monophosphate levels (cAMP). Increased cAMP activates the cAMP-dependent protein kinase (PKA), with subsequent phosphorylation of various target proteins. This beta-AR pathway interacts with several other intracellular signalling pathways via cross-talk, so that activation by beta-AR agonists may also modulate other second messengers and protein kinases. SMC beta-AR play an important role in SMC function. In intact blood vessels they mediate SMC relaxation by various intracellular mechanisms, ultimately causing a decrease in intracellular Ca2+ levels. In cultured SMC, activation of the beta-AR pathway results in inhibition of cellular proliferation, the development of SMC polyploidy, and SMC apoptosis. Blood vessels from hypertensive animals are characterized by an increase in SMC cell mass, a greater incidence of SMC polyploidy in the aorta, and an impairment in the beta-agonist-mediated SMC relaxation. Some of these changes may result from an attenuation of beta-AR function due to agonist-induced receptor desensitization caused by the uncoupling of receptors from the Gs-AC system. The phosphorylated beta-AR may in turn trigger new signals and activate different intracellular pathways. However, the details of these mechanisms are still unresolved. Since functional beta-AR play such a prominent and multi-faceted role in SMC function, it is important to understand how these diverse physiological effects are mediated by this receptor system, and how they contribute to the development of hypertension. With ageing, a decrease in beta-AR-Gs-AC coupling is observed, and this is implicated in the reduced responsiveness of SMC. The similarities in SMC beta-AR functional changes in hypertension and in ageing suggest that the underlying mechanisms are also analogous.

Recurrent Pregnancy Loss: Summary and Clinical Recommendations

Recurrent pregnancy loss (RPL) is traditionally defined as three or more consecutive pregnancy losses before 20 weeks of gestation. This problem occurs in approximately 1% of all couples and is a frustrating problem for both the patient and physician. This article provides an overview of the problem, including causes, treatments, and recommendations. Among the numerous proposed causes of RPL, only parental karyotype abnormalities, antiphospholipid syndrome, uterine malformations, and cervical incompetence are universally accepted. There are numerous treatments for RPL, but only the efficacy of heparin and low-dose aspirin in women with antiphospholipid syndrome has been established with properly controlled trials. Even after undertaking a complete evaluation, the cause of RPL remains uncertain in over 50% of cases. These patients should understand that subsequent pregnancies have up to a 70% chance of success without treatment.

Apoptosis in the muscular arteries from young spontaneously hypertensive rats

OBJECTIVE

The purpose of this study was to test the hypothesis that a different incidence of apoptosis occurs in the mesenteric arteries of the spontaneously hypertensive rat (SHR) compared with its normotensive control the Wistar-Kyoto rat (WKY) at 1-2 weeks of age.

DESIGN

We examined the incidence of apoptotic cells in the blood vessel wall of muscular arteries from the SHR and WKY at 1-2 weeks of age using two techniques of apoptosis measurement DNA laddering and 3'-OH end labelling. We also measured the volume of the blood vessel wall components and lumen sizes with the confocal microscope to determine whether a differential incidence of apoptosis occurred between the two rat strains.

METHODS

We used phenol/chloroform extraction to isolate genomic DNA and assess DNA fragmentation, with gel electrophoresis to determine DNA laddering, and 3'-OH end labelling, where the enzyme terminal deoxynucleotidyl transferase catalyses the addition of fluorescein-conjugated nucleotides to the cut ends of DNA, to detect in situ DNA fragmentation. The volume per unit length of the blood vessel structural components was measured by optical sectioning with the confocal microscope.

RESULTS

We found that the SHR had a significantly decreased incidence of cellular apoptosis over WKY. This was true for both the electrophoretic method where SHR had significantly less fragmented DNA (molecular size < 600 bp) than WKY (P= 0.01), and for the microscopic method where SHR had fewer labelled cells in both the adventitia (P= 0.01) and the media (P= 0.0001) layers of large mesenteric arteries. The volumes of the adventitia, media and lumen in the large mesenteric arteries were similar between the two strains at this age.

CONCLUSION

These findings suggest that a differential incidence of cellular apoptosis at the age of 1 -2 weeks may be responsible for the larger media volume found in older SHR and thus contributes to the development of hypertension in these animals.

Anti-beta2-glycoprotein I antibodies in women with recurrent spontaneous abortion, unexplained fetal death, and antiphospholipid syndrome

OBJECTIVE

Studies in rheumatologic and hematologic populations suggest that anti-beta(2)-glycoprotein I antibodies are more specific for the clinical manifestations of antiphospholipid syndrome than anticardiolipin antibodies. However, the association between anti-beta(2)-glycoprotein I and pregnancy loss remains uncertain. We sought to determine whether anti-beta(2)-glycoprotein I is associated with the obstetric features of antiphospholipid syndrome.

STUDY DESIGN

Sera from 4 groups of women were studied: (1) 152 healthy fertile control subjects, (2) 141 subjects with unexplained recurrent spontaneous abortions, (3) 58 subjects with unexplained fetal deaths, and (4) 73 subjects with well-characterized antiphospholipid syndrome. Serum anticardiolipin and anti-beta(2)-glycoprotein I levels were determined by enzyme-linked immunoassay.

RESULTS

Patients with antiphospholipid syndrome had significantly higher levels of immunoglobulin G and immunoglobulin M anticardiolipin and anti-beta(2)-glycoprotein I than the other 3 groups (P <.0001). However, women in the recurrent spontaneous abortion, fetal death, and fertile control groups had similar levels of each antibody. Similarly, there were no differences in the proportion of women with positive test results for each autoantibody in these 3 groups. Linear regression analysis showed significant correlation between anticardiolipin immunoglobulin G and beta(2)-glycoprotein I immunoglobulin G (R (2) = 0.544786, P =.0001) and anticardiolipin immunoglobulin M and beta(2)-glycoprotein I immunoglobulin M (R (2) = 0.525048, P =.0001).

CONCLUSION

Both anticardiolipin and anti-beta(2)-glycoprotein I are associated with antiphospholipid syndrome. However, testing for anti-beta(2)-glycoprotein I does not identify additional patients with either recurrent spontaneous abortions or unexplained fetal deaths who initially have negative test responses for anticardiolipin. This is likely because of the strong correlation between the 2 autoantibodies. Our data do not support routine testing for anti-beta(2)-glycoprotein I in addition to testing for antiphospholipid antibodies in women with recurrent pregnancy loss and unexplained fetal death.

In vitro and in vivo evaluation of a reusable double-channel sphincterotome

BACKGROUND

To date, one reusable, double-channel sphincterotome has been approved by the Food and Drug Administration in the United States. Whether this device can be reprocessed easily and whether it is more durable than currently manufactured disposable sphincterotomes are uncertain.

METHODS

Thirty double-channel, 20 mm, braided-wire sphincterotomes approved for multiple uses were studied in vitro/in vivo with regard to durability and sterilization. A cost analysis of reusable, disposable, and reprocessed disposable sphincterotomes was also carried out.

RESULTS

Three of 10 sphincterotomes evaluated in vitro broke after 3, 4, and 8 uses. Electrical integrity was preserved after 10 uses in the remaining sphincterotomes. Nine sphincterotomes remained functional for at least 3 uses, five for 6 uses, and one for 10 uses. Culture results after inoculation demonstrated contamination with surviving organisms after manual cleaning and no growth after ethylene oxide sterilization. Sixty-one procedures were performed in vivo using 20 sphincterotomes (mean number of uses 3.1). No evidence of procedurally related infection occurred with reuse. Cost per use of this reusable sphincterotome was calculated to be $62.98; it became cost effective after 2.2 and 7.9 uses when compared with disposable and reprocessed, disposable sphincterotomes, respectively.

CONCLUSIONS

This reusable sphincterotome proved to be safe, easily sterilized, and electrically intact after repeated use. In vivo, however, a progressive loss of function limited the mean number of uses to 3.1. In settings that preclude reuse of reprocessed disposable accessories, this reusable sphincterotome may provide a means to decrease costs associated with endoscopic retrograde cholangiopancreatography.

Role of Nr13 in regulation of programmed cell death in the bursa of Fabricius

Apoptotic cell death is developmentally regulated in the chicken bursa of Fabricius. Although apoptosis is low in the embryonic bursa, cell death increases markedly after hatching. The expression of Bcl2 family cell death antagonists was examined to identify the genes that regulate bursal cell apoptosis. The expression of Bcl-xL, A1, and Mcl1 was detected in both embryos and hatched birds, whereas Nr13 was expressed at high levels in embryonic bursa, and decreased significantly after hatching, correlating inversely with apoptosis. The oncogene v-reland phorbol myristate acetate, two known inhibitors of bursal cell apoptosis, induced Nr13 expression. Overexpression of Nr13 in DT40 bursal lymphoma cells protected them from low serum-induced apoptosis. The mechanism of inhibition of apoptosis by Nr13 is likely to involve a critical BH4 domain and interaction with death agonist Bax. Deletion of the BH4 domain converted Nr13 into a death agonist. Bax coimmunoprecipitated with Nr13 and Bax was induced, whereas Nr13 levels diminished when bursal lymphoblasts were induced to apoptosis by dispersion. Bursal transplantation studies demonstrated that Nr13 could prevent the in vivo programmed elimination of bursal stem cells after hatching, suggesting that Nr13 plays a role in maintaining bursal stem cells.

Two-color hybridization assay for simultaneous detection of Bordetella bronchiseptica and toxigenic Pasteurella multocida from swine

Bordetella bronchiseptica and toxigenic Pasteurella multocida are the etiologic agents of swine atrophic rhinitis. Methods currently used for their identification are time-consuming and suffer from a lack of sensitivity. We describe a colony lift-hybridization assay for detection of B. bronchiseptica and toxigenic P. multocida that can be performed with a single colony lift derived from a primary isolation plate without the need for pure subcultures of suspect bacteria. Membranes are hybridized simultaneously to probes derived from the B. bronchiseptica alcA gene and the P. multocida toxA gene. A multicolor development procedure permits sequential detection of bound probes. The assay was tested with 84 primary isolation plates generated from nasal swabs from swine with clinical signs of atrophic rhinitis. Comparison of the results from the colony lift-hybridization assay with those from conventional testing, based on a combination of colony morphology, biochemical reactions, mouse lethality, and enzyme-linked immunosorbent assay, indicated that the colony lift assay has superior sensitivity and comparable specificity. This technique has wide application for diagnostic and experimental studies.

An alternatively spliced form of apobec-1 messenger RNA is overexpressed in human colon cancer

BACKGROUND & AIMS

Apobec-1 is an RNA-specific cytidine deaminase whose forced overexpression in transgenic animals is associated with hepatic carcinogenesis. Apobec-1 messenger RNA (mRNA) undergoes alternative splicing, generating a catalytically inactive peptide, apobec-T. We have examined apobec-1 gene expression in human gastrointestinal tumors and in colon cancer-derived cell lines.

METHODS

Levels of the full-length (apobec-1) and alternatively spliced (apobec-T) mRNAs were measured by RNase protection assay, and apobec-T distribution was determined by immunocytochemical localization.

RESULTS

Apobec-1 mRNA was detectable in normal and colon cancer tissue, metastatic nodules, and certain colon cancer-derived cell lines. Apobec-T mRNA abundance was increased an average of 3.5-fold in colon cancers compared with paired control tissue (range, 0.5-14-fold). Immunocytochemical analysis showed apobec-T expression in normal fetal and adult colon and in gastric and small intestinal adenocarcinomas, colonic tubular adenomas, and both primary and metastatic colonic tumors. Overexpression of apobec-T in a tetracycline-responsive cell line decreased cellular proliferation.

CONCLUSIONS

Apobec-T is expressed in normal, adenomatous, and cancerous gastrointestinal tissues, and levels of the mRNA encoding this peptide are significantly increased in colon cancer. Although its relationship to colon carcinogenesis has not been defined, the regulated overexpression of apobec-T is associated with an altered growth phenotype.

Extramedullary facial plasmacytomas with anaplastic features: a diagnostic dilemma with implications for treatment

Extramedullary plasmacytomas (EMPs) are rare plasma-cell tumors of the soft tissue that occur predominantly in the nasal sinuses and oropharynx. Subcutaneous and cutaneous plasmacytomas of the face are distinctly unusual. The authors report a case of rapidly expanding EMP involving the lip and contralateral nasolabial fold of a native Alaskan man with a 25-year history of recurring solitary bone plasmacytomas (SBP). An incisional biopsy revealed sheets of monotypic plasmablasts with anaplastic features. The pathologic and clinical findings were most consistent with a Richter transformation from a low-grade to a high-grade malignancy, or anaplastic myeloma (AM). With combined chemotherapy and radiation therapy, he achieved a complete response. The clinical and laboratory features of this most unusual plasma-cell dyscrasia are reviewed with an emphasis placed on diagnosis and treatment.

Arterial vasodilation and vascular connective tissue changes in spontaneously hypertensive rats

Arterial hypertrophy in response to hypertension includes increases in the connective tissue proteins elastin and collagen. Regression of arterial hypertrophy depends not only on blood pressure normalization but also on the specific antihypertensive treatment. Consequently, each drug class may exert an influence on connective tissue proteins. We evaluated the arterial connective tissue response of 16-week-old spontaneously hypertensive rats (SHRs) to treatment with minoxidil, 120 mg/L, drinking water for 10 weeks. Despite a decrease in blood pressure, minoxidil had no effect on arterial weight or collagen content but increased elastin content in the abdominal aorta, renal, and superior mesenteric arteries. The increase in elastin content in the abdominal aorta and superior mesenteric artery was accompanied by a decrease in tissue elastase activity. Thus the minoxidil-induced increase in arterial elastin content may be related to a direct effect of the drug to decrease elastase activity in these tissues.

Risk of contamination of sterile biopsy forceps in disinfected endoscopes

BACKGROUND

Previous studies have shown that pathogens may persist within bacterial biofilms in endoscope accessory channels despite high-level disinfection. Breaching the gastrointestinal mucosa with biopsy forceps contaminated at time of passage has the potential to cause cross-infection between patients.

METHODS

We studied contamination risk of sterilized biopsy forceps passed through endoscopes after high-level disinfection. For each trial, five video colonoscopes, duodenoscopes, and gastroscopes were used. All endoscopes had been previously processed and stored for 10 or more hours. Sterile biopsy forceps were inserted and retrieved followed by vortexing the tips in 15 mL of soy broth. Under a laminar flow hood, the broth was filtered through a 0.2 microm millipore membrane and plated. Because of minimal bacterial growth resulting from the above, soy broth (> 20 mL) was flushed through two video colonoscopes, duodenoscopes, and gastroscopes on two occasions and collected. The effluent was plated using a sample of 0.1 mL dilution. The remaining suspension was passed through a millipore filter, and the filter was cultured. All cultures were incubated more than 48 hours.

RESULTS

Biopsy forceps underwent a total of 24 anaerobic and 75 aerobic cultures. Microbacterial growth occurred on 17 plates: 7 from gastroscopes, 5 from colonoscopes, and 5 from duodenoscopes. Fifteen plates grew staphylococcus for a total of 21 colonies, 1 plate grew 1 colony of propionibacter, 2 plates grew diphtheroids for a total of 4 colonies, and 1 plate grew a single colony of lactobacillus. Cultures from soy broth flushed through the various endoscopes grew on 5 plates: 3 from gastroscopes and 2 from duodenoscopes grew a total of 8 colonies of staphylococcus.

CONCLUSIONS

With proper cleaning technique, a 20-minute soak in 2% glutaraldehyde is effective in disinfecting endoscopes. Although current procedures for endoscope disinfection remain imperfect, we found that in this clinical setting, infection of pathogenic gastrointestinal flora is unlikely when using sterile biopsy forceps.

Cross-over study comparing effects of treatment with an angiotensin converting enzyme inhibitor and an angiotensin II type 1 receptor antagonist on cardiovascular changes in hypertension

OBJECTIVE

To compare the blood-pressure-lowering effects of an angiotensin converting enzyme inhibitor, perindopril, with those of an angiotensin II type 1 receptor antagonist, L-158,809, for adult spontaneously hypertensive rats.

DESIGN

A cross-over design was used, to treat adult spontaneously hypertensive rats with one drug for 10 weeks, and then with the other for 5 weeks.

METHODS

Adult, male spontaneously hypertensive rats (aged 15 weeks) were treated daily by gavage for 10 weeks with perindopril (P group) or L-158,809 (L group), then treatment was crossed over so that rats in the P group were treated with L-158,809 (P/L group) and rats in the L group were treated with perindopril (L/P group) for 5 weeks. Blood pressure was measured weekly. Plasma angiotensin converting enzyme activity, renal angiotensin receptor density, and arterial structure and functioning were measured after the single and crossover treatment periods.

RESULTS

Treatment lowered the blood pressure from 206 +/- 2 mmHg in rats in the control group, to 126 +/- 2 in rats in the P group and 150 +/- 2 in rats in the L group. After the cross-over period, blood pressure decreased further from 150 +/- 2 to 129 +/- 3 mmHg in rats in the L/P group, whereas blood pressure of spontaneously hypertensive rats in the P/L group increased from 126 +/- 2 to 148 +/- 2 mmHg. Perindopril treatment almost abolished plasma angiotensin converting enzyme activity, whereas L-158,809 treatment had no effect. Renal angiotensin II receptor density was decreased versus baseline in rats in the P and L groups. The affinity of binding was decreased versus baseline in rats in the L group. A positive correlation to blood pressure was found for mesenteric artery wall thickness and wall: lumen ratio. Concentration for half-maximal effect for the response of mesenteric arteries from rats in the P group to norepinephrine was lower than that of the control group rats. Angiotensin II potentiated the norepinephrine-stimulated contraction of arteries from rats in the control and P groups, but not that of arteries from rats in the groups treated with L-158,809.

CONCLUSION

Perindopril was more effective than was L-158,809 at lowering the blood pressure of adult spontaneously hypertensive rats, and at altering the structure and functioning of the arteries.

Blood pressure and heart rate development in young spontaneously hypertensive rats

The course of hypertension development in young spontaneously hypertensive rats (SHR) was studied by the measurement of changes in systolic blood pressure (BP), body weight, and heart rate (HR) at 2, 3, 4, and 6 wk of age. To achieve this, we compared inbreeding lines of SHR and Wistar-Kyoto rats (WKY) to determine if differences in BP, body weight, or HR were present among inbreeding lines of the same strain or between strains. The effect of these differences on the eventual level of BP was then assessed. We found that BP began to diverge between SHR and WKY at 4 wk of age. Significant differences in systolic BP (24 mmHg) between SHR inbreeding lines at 4 wk of age did not affect the BP at 8 wk (172 vs. 170 mmHg). Pulse pressure was significantly higher in SHR than in WKY at 4 wk of age. HR was elevated in SHR over age-matched WKY at 3 wk of age and positively correlated to the level of BP attained by individual animals at 6 wk (P = 0.037). Moreover, WKY inbreeding lines showing elevated HR developed higher BP (145 vs. 127 mmHg) at 10-12 and 20 wk of age. The prehypertensive tachycardia in SHR was investigated further and found to result from an increased intrinsic HR. Because HR at 3 wk is a genetic trait that can be partitioned into inbreeding lines, and inbreeding lines most expressive of this trait showed the highest eventual BP, we conclude that prehypertensive tachycardia may be an important first step during hypertension development in SHR. Moreover, early elevations in HR are highly predictive (r = 0.41) of hypertension occurrence in the animal population studied.

The effects of dietary sodium on hypertension and stroke development in female stroke-prone spontaneously hypertensive rats

Previous studies on male stroke-prone spontaneously hypertensive rats (SHRSP) have shown that a high-salt diet accelerated the onset of hypertension and stroke, resulting in an increased mortality rate at a younger age. The purpose of this study was to examine whether a similar effect is present in female SHRSP. After weaning at 4 weeks of age, 32 female SHRSP were placed on a Japanese-style rat diet containing either 0.3% NaCl or 4% NaCl. Blood pressure (BP), heart rate, and body weight were measured weekly. Beginning at 9 weeks of age, the SHRSP on the 4% NaCl diet began to show a consistently and significantly higher BP than those in the 0.3% NaCl group, reaching an average BP of 245 +/- 9 mmHg at 16 weeks of age as compared to 184 +/- 3 mmHg in the 0.3% NaCl group. Some female SHRSP in the 4% NaCl group started to exhibit behavioral signs of stroke at 12 weeks of age and 100% mortality was found by 20 weeks. There was 0% mortality in the 0.3% NaCl group at that age. A positive correlation was found between the age at which BP surpassed 220 mmHg and the age death occurred due to stroke. No significant difference was noted in the heart rate or body weight measurements between the two groups. The increased mortality rate in the 4% NaCl diet group was accompanied by organ damage as evidenced by the presence of left ventricular hypertrophy, edematous kidneys, renal malfunction, kidney lesions, and cerebral lesions in these female SHRSP. It is concluded that a high-salt diet exacerbates hypertension and caused an increased mortality rate. This increased mortality rate was associated with an increased left ventricular hypertrophy, kidney damage and subsequent malfunction, and cerebrovascular lesions in these female SHRSP.

Correlation of vascular smooth muscle cell morphology observed by scanning electron microscopy with transmission electron microscopy

Smooth muscle cell (SMC) morphology was studied in rat large mesenteric artery using scanning electron microscopy (SEM), after removal of connective tissue elements with the OsO4/HCl method. Transmission electron microscopy (TEM) was used to correlate the findings of SEM and to assess the effects of digestion on cell ultrastructure. When viewed with SEM, relaxed SMC possessed a smooth, regular surface morphology with longitudinal striations or grooves. TEM examination of cross-sectional profiles of SMC suggested that these striations corresponded to the arrangement of membrane dense bodies within the SMC. The presence of cell contacts among SMC as observed with SEM were confirmed using TEM. Two types of SMC contacts were found: simple appositional contacts and interdigitations. Gap junctions were not observed between SMC in the media. Although structures suggesting nerve networks were observed in the medial-adventitial border with SEM, this could not be confirmed using TEM as a result of alteration in cell ultrastructure with the digestive method. We conclude that the OsO4/HCl method, although useful for SEM, is not suitable for TEM study, because it caused significant alterations of SMC ultrastructure such that organelles and other structures were no longer evident when viewed with TEM.

Prevention of stroke and preservation of the functions of cerebral arteries by treatment with perindopril in stroke-prone spontaneously hypertensive rats

The aim of this study was to determine whether the prevention of stroke with perindopril treatment in stroke-prone spontaneously hypertensive rats (SHRSP) is associated with the preservation of the myogenic properties of the cerebral arteries. After weaning at 4 weeks of age, male SHRSP were fed a Japanese-style rat diet with high salt to induce stroke development. Treatment with perindopril was given by gavage every morning beginning at 6 weeks of age. There were three experimental groups: two groups treated with 4 mg.kg-1.day-1 perindopril for different durations (8 or 12 weeks) and one control group consisting of littermates given distilled water. All the control animals developed stroke and died within 14 weeks of age, and myogenic response of the middle cerebral arteries (MCA) to pressure increase was lost in these animals. In contrast, all the treated SHRSP survived during the treatment period, and myogenic response of the MCA was preserved. After withdrawal of the treatment, SHRSP treated for a longer period (12 weeks) also survived longer than those treated for a shorter period (8 weeks). The subsequent development of stroke and death following treatment withdrawal after 8 or 12 weeks of treatment was associated with the loss of pressure-dependent constriction in MCA. A longer treatment duration also increased the stiffness of the MCA, MCA from SHRSP after 12 weeks of treatment had smaller external and lumen diameters, and thicker walls than those from the 8-week treatment group. In a separate study, we found that treatment of SHRSP with 1 or 4 mg.kg-1.day-1 of perindopril for 24 weeks beginning at 6 weeks of age also protected them against death related to stroke, because these rats survived up to 43 weeks of age, when the experiment was terminated. We conclude that there is an association between the absence of myogenic response in cerebral arteries and stroke development in SHRSP. Perindopril treatment preserves the myogenic response of MCA in SHRSP and prevents the stroke development in these animals. A prolonged treatment could increase the survival of SHRSP through a remodelling of the MCA and increasing the stiffness of the cerebral arteries.

AT1 receptor antagonist treatment caused persistent arterial functional changes in young spontaneously hypertensive rats

The effects of chronic treatment with an AT1 receptor antagonist (L-158,809) on hypertension development and cardiovascular changes were studied in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). L-158,809 treatment (0.6 mg/kg PO) was initiated at 3 weeks of age and lasted 12 weeks, to 15 weeks of age. The treatment prevented hypertension development in the SHR (systolic blood pressure, BP, of 136+/-1 mm Hg compared with 198+/-3 mm Hg in control SHR), and lowered the BP of WKY (99+/-2 vs 128+/-1 mm Hg in control WKY). Treatment significantly reduced the heart weight in SHR and WKY. Ten weeks after treatment withdrawal (25 weeks of age), BP had increased in SHR and WKY to 172+/-8 and 117+/-3 mm Hg, respectively. Body weight and kidney weight were not affected by the treatment. Mesenteric arteries from treated SHR were less responsive than control SHR arteries to periarterial nerve stimulations at transmural pressures higher than 80 mm Hg (15 and 25 weeks). Control WKY arteries were less responsive than control SHR arteries at almost all transmural pressures tested (15 weeks) and to pressures greater than 80 mm Hg (25 weeks). Pretreatment of arteries with 10(-8) mol/L angiotensin II enhanced their response to nerve stimulation in vessels from control SHR and WKY (25 weeks) but not from treatment-withdrawn SHR and WKY. Treatment did not alter arterial reactivity in response to norepinephrine. Alteration in arterial structure due to L-158,809 treatment was found only when measured at a transmural pressure of 100 mm Hg. In conclusion, L-158,809 was effective in preventing hypertension during the treatment period, in reducing hypertension severity during the withdrawal period, and in persistently decreasing the reactivity of the arteries.

Prevention of stroke with perindopril treatment in stroke-prone spontaneously hypertensive rats

OBJECTIVE

To determine the protective effects of perindopril treatment in the prevention of stroke and the relation between preventive effects and the histopathology of the brain and kidneys in male stroke-prone spontaneously hypertensive rats (SHRSP).

DESIGN

Prospective animal study.

INTERVENTIONS

Beginning at 6 weeks of age, SHRSP were treated with either distilled water (control) or perindopril for different periods (8, 12 or 24 weeks) and at different dosages (1 or 4 mg/kg per day).

OUTCOME MEASURES

Regular determination of systolic blood pressure, heart rate and body weight until death; at necropsy, macroscopic and microscopic examinations of the brain and kidneys.

RESULTS

Control SHRSP developed severe hypertension (up to 250 mm Hg) by 11 weeks of age and died of stroke within 14 weeks of age. Treatment with perindopril (4 mg/kg per day for 8 or 12 weeks or either 1 or 4 mg/kg per day for 24 weeks) attenuated the blood pressure rise and prevented stroke. In untreated SHRSP, the last blood pressure measurement before the first stroke sign was significantly higher than in SHRSP of the same age treated with perindopril. Withdrawal of the treatment resulted in a rise in blood pressure in all the treatment groups, to approximately 260 mm Hg within 4 weeks. Most of the rats treated for 8 or 12 weeks died within 10 weeks after withdrawal of treatment, whereas those treated for 24 weeks survived up to 43 weeks of age. Treatment also prevented damage to the brain and kidneys and reduced the severity of lesions in the brain and kidneys after treatment withdrawal.

CONCLUSION

Treatment of SHRSP with perindopril prevents stroke through the suppression of blood pressure rise and prevention of tissue damage in the brain and the kidneys. Longer treatment decreased the rate of mortality due to stroke after the withdrawal of treatment as well as the severity of lesions in the brain and kidneys.

Antihypertensive effects of perindopril treatment in adult spontaneously hypertensive rats

OBJECTIVE

To determine the effect of perindopril treatment and treatment withdrawal in the prevention of hypertension in adult male spontaneously hypertensive rats (SHR).

ANIMALS AND METHODS

Beginning at 15 weeks of age, male SHR were treated with either distilled water (control) or different daily dosages of perindopril (1, 2 or 4 mg/kg) by gavage for 10 weeks, followed by 10 weeks of treatment withdrawal. Systolic blood pressure, heart rate and body weight of adult SHR were determined at regular intervals before, during and after the treatment withdrawal periods. At the end of the treatment withdrawal period, plasma and tissue samples were taken for measurement of noradrenaline levels. Angiotensin-converting enzyme (ACE) activity in the plasma from adult SHR and Wistar-kyoto (WKY) rats treated with perindopril 4 mg/kg for two weeks was measured by a radioassay method 6 and 24 h after treatment.

RESULTS

Treatment with perindopril caused a dose-dependent lowering of blood pressure in SHR during the 10-week treatment. After withdrawal of the treatment, persistent lowering of blood pressure was found in SHR treated with higher dosages (2 or 4 mg/kg), but not in the 1 mg/kg group. There was no difference in the tissue level of noradrenaline among the control group and SHR previously treated with perindopril. In SHR and WKY treated with perindopril for two weeks, plasma level of ACE activity was reduced longer than 24 h compared with their respective controls.

CONCLUSIONS

Chronic treatment of adult SHR with perindopril has a dose-dependent effect on the blood pressure of these animals both during and after withdrawal of treatment, but such a treatment had no long term effects on the noradrenaline levels in various tissues.

Expression of functional beta-adrenoceptors and polyploidy development in cultured vascular smooth muscle cells from spontaneously hypertensive rats

The main objective of this study was to investigate the role of beta-adrenoceptor activation in the development of polyploidy in these cells. Smooth muscle cells (SMCs) were cultured from 3- to 4-, 10- to 12-, and 28- to 30-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Functional expression of beta-adrenoceptors was examined by treatment of cultured SMCs with a nonselective beta-adrenoceptor agonist, isoproterenol, or an adenylate cyclase activator, forskolin, or a membrane-permeable analog of adenosine 3',5'-cyclic monophosphate (cAMP), 8-bromo-cAMP, and the measurement of intracellular cAMP levels, using a radioimmunoassay. The effects of these treatments on polyploidy development were also studied by measuring the DNA content of SMCs, using scanning microdensitometry. Treatments with isoproterenol or forskolin increased intracellular cAMP levels in both strains of rats in all three age groups. Addition of the beta-adrenoceptor antagonist DL-propranolol inhibited the isoproterenol-stimulated response in SMCs from both SHR and WKY in all three age groups. The number of polyploid SMCs was significantly increased by treatments with isoproterenol, forskolin, or 8-bromo-cAMP in SMCs from 3- to 4-week-old WKY and SHR, but in the 10- to 12-week age group, an increase was found only in SMCs from WKY. Such treatments had no effect on the incidence of polyploid SMCs in the 28- to 30-week groups. We conclude that (i) beta-adrenoceptors expressed by the SMCs from WKY and SHR at all three ages are functional and are coupled via Gs proteins to the stimulation of adenylate cyclase, (ii) treatments that elevate intracellular cAMP levels (by activation of beta-adrenoceptors or of adenylate cyclase) lead to increased polyploid SMCs from WKY and SHR in the younger age group, confirming a role for the beta-adrenoceptor-adenylate cyclase pathway in the development of polyploidy in cultured SMCs from both of these strains of rats, and (iii) the absence of these treatment effects in the induction of polyploid SMCs in older age groups suggests that in these cells, other factors or processes may be involved in regulating the development of polyploid SMCs.

Structural and functional analysis of small arteries from young spontaneously hypertensive rats

We studied structural and functional changes of small muscular arteries from the mesenteric vascular bed of young spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) using a new morphometric protocol involving the use of confocal microscopy and a pressurized artery system. At 3 and 4 weeks of age, systolic pressure of SHR and WKY was similar; however, significant structural changes in the mesenteric vasculature were already present in SHR. Arteries fixed under pressure in vitro from SHR had a larger medial volume and increased number of smooth muscle cell layers but similar lumen size compared with arteries from WKY in maximally relaxed conditions. Functional studies showed that SHR arteries contracted more in response to stimulation by KCl and norepinephrine, resulting in a significantly smaller lumen size in these vessels than in those from WKY. SHR arteries precontracted with KCl were also able to maintain a smaller lumen diameter than WKY arteries when challenged with increasing pressure levels. No difference in the sensitivity of response of these arteries to norepinephrine stimulation was found. At 3 and 4 weeks of age, mesenteric arteries from some SHR and WKY were not responsive to periarterial nerve stimulation, and the number of responders was higher in the WKY than SHR. However, a greater degree of contraction was found in SHR arteries responding to field stimulation at 4 weeks than in WKY arteries. We conclude that there is a temporal difference in the rate of functional maturation of the innervation in SHR arteries compared with WKY arteries. Structural changes of the small muscular arteries, caused by an increase in the medial volume, and increased number of smooth muscle cell layers are primary changes that contribute to the development of hypertension in the SHR because these changes are present at the age when blood pressure is similar in SHR and WKY.