Assessment of antihypertensive treatment by ambulatory blood pressure

TRIM Proteins in Host Defense and Viral Pathogenesis

Purpose of Review

Tripartite motif (TRIM) proteins are a large group of E3 ubiquitin ligases involved in different cellular functions. Of special interest are their roles in innate immunity, inflammation, and virus replication. We discuss novel roles of TRIM proteins during virus infections that lead to increased pathogenicity.

Recent Findings

TRIM proteins regulate different antiviral and inflammatory signaling pathways, mostly by promoting ubiquitination of important factors including pattern recognition receptors, adaptor proteins, kinases, and transcription factors that are involved in type I interferon and NF-κB pathways. Therefore, viruses have developed mechanisms to target TRIMs for immune evasion. New evidence is emerging indicating that viruses have the ability to directly use TRIMs and the ubiquitination process to enhance the viral replication cycle and cause increased pathogenesis. A new report on TRIM7 also highlights the potential pro-viral role of TRIMs via ubiquitination of viral proteins and suggests a novel mechanism by which ubiquitination of virus envelope protein may provide determinants of tissue and species tropism.

Summary

TRIM proteins have important functions in promoting host defense against virus infection; however, viruses have adapted to evade TRIM-mediated immune responses and can hijack TRIMs to ultimately increase virus pathogenesis. Only by understanding specific TRIM-virus interactions and by using more in vivo approaches can we learn how to harness TRIM function to develop therapeutic approaches to reduce virus pathogenesis.

In vivo expression of angiotensin-(1-7) lowers blood pressure and improves baroreflex function in transgenic (mRen2)27 rats

Transgenic (mRen2)27 rats are hypertensive with impaired baroreflex sensitivity for control of heart rate compared with Hannover Sprague-Dawley rats. We assessed blood pressure and baroreflex function in male hemizygous (mRen2)27 rats (30-40 weeks of age) instrumented for arterial pressure recordings and receiving into the cisterna magna either an Ang-(1-7) fusion protein or a control fusion protein (CTL-FP). The maximum reduction in mean arterial pressure achieved was -38 ± 7 mm Hg on day 3, accompanied by a 55% enhancement in baroreflex sensitivity in Ang-(1-7) fusion protein-treated rats. Both the high-frequency alpha index (HF-α) and heart rate variability increased, suggesting increased parasympathetic tone for cardiac control. The mRNA levels of several components of the renin-angiotensin system in the dorsal medulla were markedly reduced including renin (-80%), neprilysin (-40%), and the AT1a receptor (-40%). However, there was a 2-fold to 3-fold increase in the mRNA levels of the phosphatases PTP-1b and dual-specificity phosphatase 1 in the medulla of Ang-(1-7) fusion protein-treated rats. Our finding that replacement of Ang-(1-7) in the brain of (mRen2)27 rats reverses in part the hypertension and baroreflex impairment is consistent with a functional deficit of Ang-(1-7) in this hypertensive strain. We conclude that the increased mRNA expression of phosphatases known to counteract the phosphoinositol 3 kinase and mitogen-activated protein kinases, and the reduction of renin and AT1a receptor mRNA levels may contribute to the reduction in arterial pressure and improvement in baroreflex sensitivity in response to Ang-(1-7).

Efficacy and safety of two treatment combinations of hypertension in very elderly patients

The study compared valsartan/amlodipine combination with irbesartan/hydrochlorothiazide (HCTZ) combination in very elderly hypertensives. After a 4-week placebo period, 94 hypertensives, aged 75-89 years were randomized to valsartan 160mg/amlodipine 5mg or irbesartan 300mg/HCTZ 12.5mg for 24 weeks according to a prospective, parallel group study. After 4 weeks amlodipine or HCTZ was doubled in non-responders. Patients were checked every 4 weeks. At each visit clinical sitting, lying and standing blood pressure (BP), systolic BP (SBP) and diastolic BP (DBP) were evaluated, and an electrocardiogram was performed. At the end of the placebo period and of the treatment period a non-invasive 24-h ambulatory BP monitoring (ABPM) was performed and electrolytes and uric acid were evaluated. Both combinations significantly reduced ambulatory BP. In the valsartan/amlodipine group the mean reduction (-29.9/-15.6 for 24h, -28.6/-14.5mmHg for day-time and -26.2/-17.4mmHg for night-time SBP/DBP) was similar to that of the irbesartan/HCTZ group (-29.6/-15.4 for 24h, -29.3/-14.9mmHg for day-time and -25.4/-16.9mmHg for night-time SBP/DBP). Both combinations significantly reduced clinical sitting and lying BP values with no difference between treatments. BP changes from lying to standing position were significantly greater in the irbesartan/HCTZ group (-17.2/-9.1mmHg) than in the valsartan/amlodipine group (-10.1/-1.9mmHg, p<0.05 for SBP and p<0.01 for DBP vs. irbesartan/HCTZ). Potassium significantly decreased and uric acid significantly increased (-0.4mmol/l, p<0.05 and +0.5mg/dl, p<0.05 vs. baseline, respectively) only in the irbesartan/HCTZ group. In conclusion, both combinations were similarly effective in reducing ambulatory and clinical BP in very elderly hypertensives. However, valsartan/amlodipine offered some advantages in terms of less pronounced BP orthostatic changes and absence of metabolic adverse effects.

Fixed combination of manidipine and delapril in the treatment of mild to moderate essential hypertension: evaluation by 24-hour ambulatory blood pressure monitoring

This present study assessed the antihypertensive efficacy of the fixed combination of manidipine and delapril by ambulatory blood pressure monitoring in patients with hypertension inadequately controlled by monotherapy with either component. After a 2-week placebo period, 55 mild to moderate hypertensive patients were randomized to manidipine 20 mg o.d. or delapril 30 mg b.i.d. for 4 weeks. After this period, 30 patients, aged 30-76 years (18 males and 12 females) whose diastolic blood pressure was not adequately controlled (> or = 90 mmHg) by monotherapy were treated with the fixed combination of manidipine 10 mg plus delapril 30 mg o.d. for 8 weeks. A 24-h ambulatory blood pressure monitoring recording was performed at the end of the placebo washout, of the monotherapy and of the combination therapy. Blood pressure control over the 24 h was quantified by the trough-to-peak ratio and the smoothness index. As compared to placebo, the fixed combination of manidipine and delapril produced a statistically significant (p<0.01) decrease in sitting clinic (18 +/- 9/14 +/- 5 mmHg) and 24-h blood pressure (12 +/- 7/10 +/- 5 mmHg) without affecting heart rate. This reduction was greater than that observed with single components. At the end of the 8-week combination treatment period, the rate of normalilized patients was 73%. Treatment with the fixed combination was associated with a positively high smoothness index (1.2 +/- 0.7/13.8 +/- 0.8) and with a relatively good trough-to-peak ratio (0.46/0.60). The combination of manidipine and delapril produced significant and smooth reductions in blood pressure values, which persisted over the 24-h dosing interval. These results support the use of fixed manidipine-delapril combination in the treatment of mild to moderate hypertensive patients inadequately controlled by monotherapy.

Factors influencing blood pressure: development of a risk model

A review of the literature suggests that blood pressure (BP) is multifactorial and is affected by the interactions of genetics, physiology, responses to the environment, and lifestyle factors that have increasing influence as one ages. The effect of these factors on hypertension (HTN) risk as one ages is depicted in the author's Hypertension Risk Model. The model emphasizes HTN risk in the older adult--age 50 and older--and shows the interaction of the factors influencing HTN development and BP assessment methods. Implications of three methods of BP assessment--(1) static BP, (2) 24-hour ambulatory blood pressure monitoring, and (3) clinic blood pressure reactivity (BPR) protocol--are discussed. The model may be useful for understanding factors that contribute to HTN and for guiding BP assessment for clinical researchers. Addressing the factors associated with the sympathetic system activity from various environmental stressors requires assessing dynamic BP, particularly in the older hypertensive adult who has increased BPR. Further research should focus on ambulatory blood pressure studies in older adults that would provide the methods and instrumentation needed to assess HTN and therefore decrease mortality and morbidity in this population.

1999 World Health Organization-International Society of Hypertension Guidelines for the management of hypertension. Guidelines sub-committee of the World Health Organization

The present Guidelines were prepared by the Guidelines Sub-Committee of the World Health Organization-International Society of Hypertension (WHO-ISH) Mild Hypertension Liaison Committee, the members of which are listed at the end of the text. These guidelines represent the fourth revision of the WHO-ISH Guidelines and were finalised after presentation and discussion at the 7th WHO-ISH Meeting on Hypertension, Fukuoka, Japan, 29th Sept-1st Oct, 1998. Previous versions of the Guidelines were published in Bull WHO 1993, 71:503-517 and J Hypertens 1993, 11:905-918.