Genetic Loss of miR-205 Causes Increased Mammary Gland Development

MiRNAs play crucial roles in a broad spectrum of biological processes, both physiological and pathological. Different reports implicate miR-205 in the control of breast stem cell properties. Differential miR-205 expression has been observed in different stages of mammary gland development and maturation. However, a functional role in this process has not been clearly demonstrated. We generated an miR-205 knockout in the FVB/N mouse strain, which is viable and characterized by enhanced mammary gland development. Indeed, mammary glands of miR-205-/- female mice at different ages (1.5 and 5.5 months) show increased outgrowth and branching. This evidence is consistent with our previously reported data demonstrating the direct miR-205-mediated targeting of HER3, a master regulator of mammary gland development, and the oncosuppressive activity of this microRNA in different types of breast cancer.

Fhit-Fdxr interaction in the mitochondria: modulation of reactive oxygen species generation and apoptosis in cancer cells

Fhit protein is lost in cancers of most, perhaps all, cancer types; when restored, it can induce apoptosis and suppress tumorigenicity, as shown in vitro and in mouse tumor models in vivo. Following protein cross-linking and proteomics analyses, we characterized a Fhit protein complex involved in triggering Fhit-mediated apoptosis. The complex includes the heat-shock chaperonin pair, HSP60/10, which is likely involved in importing Fhit into the mitochondria, where it interacts with ferredoxin reductase, responsible for transferring electrons from NADPH to cytochrome P450 via ferredoxin, in electron transport chain complex III. Overexpression of Fhit protein in Fhit-deficient cancer cells modulates the production of intracellular reactive oxygen species, causing increased ROS, following peroxide treatment, with subsequent increased apoptosis of lung cancer cells under oxidative stress conditions; conversely, Fhit-negative cells escape ROS overproduction and ROS-induced apoptosis, likely carrying oxidative damage. Thus, characterization of Fhit-interacting proteins has identified direct effectors of a Fhit-mediated apoptotic signal pathway that is lost in many cancers. This is of translational interest considering the very recent emphasis in a number of high-profile publications, concerning the role of oxidative phosphorylation in the treatment of human cancers, and especially cancer stem cells that rely upon oxidative phosphorylation for survival. Additionally, we have shown that cells from a Fhit-deficient lung cancer cell line, are sensitive to killing by exposure to atovaquone, thought to act as a selective oxidative phosphorylation inhibitor by targeting the CoQ10 dependence of the mitochondrial complex III, while the Fhit-expressing sister clone is resistant to this treatment.

Abstract 1850: CDK inhibitor PHA-848125 preferentially inhibits proliferation of triple negative breast cancer and synergizes with cisplatin

Triple-negative breast cancer (TNBC), defined by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), is highly aggressive with a poor prognosis as it lacks targeted therapies. Several inhibitors of the cyclin-dependent kinase 4 and 6 (CDK4/6) have been approved by the FDA for the treatment of ER-positive breast cancer. However, the effectiveness of these inhibitors against TNBC tumors is less than expected. Here, we tested the efficacy of PHA-848125, a potent ATP-competitive CDK2 inhibitor, on a panel of breast cancer cell lines showing a selective impaired proliferation in TNBC cells (IC50 of ER-positive MCF7 cells: 25.9 μM vs. IC50 of TNBC MDA-MB-231 cells: 430.8 nM). TNBC cells treated with PHA-848125 exhibited effects consistent with CDK2 inhibition, including G1 cell cycle arrest and reduced phosphorylation levels of the retinoblastoma protein (pRB) and CDK2. Interestingly, PHA-848125 was also effective against pRB-null TNBC cell lines, unlike other approved CDK inhibitors. Oral administration of PHA-848125 to TNBC xenograft mice and MMTV-PyMT transgenic mice impaired both tumor growth and metastasis at a tolerable dose (40 mg/kg), but not in ER-positive xenograft mice. A combination treatment of PHA-848125 and cisplatin inhibited tumor growth and induced apoptosis synergistically in vitro and in vivo. Thus, our preclinical experiments set the rationale for the clinical evaluation of PHA-848125, either alone or in combination with cisplatin, for the treatment of TNBC.

Citation Format: Douglas G. Cheung, Marta Buzzetti, Carlo M. Croce, Gianpiero di Leva. CDK inhibitor PHA-848125 preferentially inhibits proliferation of triple negative breast cancer and synergizes with cisplatin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1850.

miRNAs in bone metastasis

Bone metastasis is one of the most common forms of metastasis from a number of different primary carcinomas. MicroRNAs (miRNAs) are short, endogenous RNAs that negatively regulate gene expression to control essential pathways, including those involved in bone organogenesis and homeostasis. As these pathways are often hijacked during bone metastasis, it is not surprising that miRNAs can also influence bone metastasis formation. Areas covered: In this review, we first summarize the major signalling pathways involved in normal bone development and bone metastasis. We will then discuss the overall roles of miRNAs in cancer metastasis and highlight the recent findings on the effects of miRNAs in bone metastasis. To this aim, we have performed a literature search in PubMed by using the search words 'miRNAs' and 'bone metastasis', selecting relevant scientific articles published between 2010 and 2016. Seminal publications before 2010 on the metastatic role of miRNAs have also been considered. Expert commentary: With the lack of current diagnostic biomarkers and effective targeted therapies for bone metastasis, the significant role of miRNAs in the regulation of bone homeostasis and bone metastasis may support the future use of miRNAs as diagnostic biomarkers and therapeutic targets.

Determination of absolute expression profiles using multiplexed miRNA analysis

Accurate measurement of miRNA expression is critical to understanding their role in gene expression as well as their application as disease biomarkers. Correct identification of changes in miRNA expression rests on reliable normalization to account for biological and technological variance between samples. Ligo-miR is a multiplex assay designed to rapidly measure absolute miRNA copy numbers, thus reducing dependence on biological controls. It uses a simple 2-step ligation process to generate length coded products that can be quantified using a variety of DNA sizing methods. We demonstrate Ligo-miR's ability to quantify miRNA expression down to 20 copies per cell sensitivity, accurately discriminate between closely related miRNA, and reliably measure differential changes as small as 1.2-fold. Then, benchmarking studies were performed to show the high correlation between Ligo-miR, microarray, and TaqMan qRT-PCR. Finally, Ligo-miR was used to determine copy number profiles in a number of breast, esophageal, and pancreatic cell lines and to demonstrate the utility of copy number analysis for providing layered insight into expression profile changes.

miR-302b enhances breast cancer cell sensitivity to cisplatin by regulating E2F1 and the cellular DNA damage response

The identification of the molecular mechanisms involved in the establishment of the resistant phenotype represents a critical need for the development of new strategies to prevent or overcome cancer resistance to anti-neoplastic treatments.Breast cancer is the leading cause of cancer-related deaths in women, and resistance to chemotherapy negatively affects patient outcomes. Here, we investigated the potential role of miR-302b in the modulation of breast cancer cell resistance to cisplatin.miR-302b overexpression enhances sensitivity to cisplatin in breast cancer cell lines, reducing cell viability and proliferation in response to the treatment. We also identified E2F1, a master regulator of the G1/S transition, as a direct target gene of miR-302b. E2F1 transcriptionally activates ATM, the main cellular sensor of DNA damage. Through the negative regulation of E2F1, miR-302b indirectly affects ATM expression, abrogating cell-cycle progression upon cisplatin treatment. Moreover miR-302b, impairs the ability of breast cancer cells to repair damaged DNA, enhancing apoptosis activation following cisplatin treatment.These findings indicate that miR-302b plays a relevant role in breast cancer cell response to cisplatin through the modulation of the E2F1/ATM axis, representing a valid candidate as therapeutic tool to overcome chemotherapy resistance.

miRNA clusters as therapeutic targets for hormone-resistant breast cancer

MicroRNAs are small non coding RNAs that typically inhibit the translation and stability of messenger RNAs, controlling genes involved in cellular processes such as inflammation, cell cycle regulation, stress response, differentiation, apoptosis, and migration. Not surprisingly, microRNAs are also aberrantly expressed in cancer and promote tumorigenesis by disrupting these vital cellular functions. In this review, we first broadly summarize the role of microRNAs in breast cancer and Estrogen Receptor alpha signaling. Then we focus on what is currently known about the role of microRNAs in anti-hormonal therapy or resistance to endocrine agents. Specifically, we will discuss key miRNAs involved in tamoxifen (miR-221/222, 181, 101, 519a, 301, 375, 342, 451, and the let-7 family), fulvestrant (miR-221/222, miR-200 family), and aromatase inhibitor (miR-128 and the let-7 family) resistance.

Estrogen mediated-activation of miR-191/425 cluster modulates tumorigenicity of breast cancer cells depending on estrogen receptor status

MicroRNAs (miRNAs), single-stranded non-coding RNAs, influence myriad biological processes that can contribute to cancer. Although tumor-suppressive and oncogenic functions have been characterized for some miRNAs, the majority of microRNAs have not been investigated for their ability to promote and modulate tumorigenesis. Here, we established that the miR-191/425 cluster is transcriptionally dependent on the host gene, DALRD3, and that the hormone 17β-estradiol (estrogen or E2) controls expression of both miR-191/425 and DALRD3. MiR-191/425 locus characterization revealed that the recruitment of estrogen receptor α (ERα) to the regulatory region of the miR-191/425-DALRD3 unit resulted in the accumulation of miR-191 and miR-425 and subsequent decrease in DALRD3 expression levels. We demonstrated that miR-191 protects ERα positive breast cancer cells from hormone starvation-induced apoptosis through the suppression of tumor-suppressor EGR1. Furthermore, enforced expression of the miR-191/425 cluster in aggressive breast cancer cells altered global gene expression profiles and enabled us to identify important tumor promoting genes, including SATB1, CCND2, and FSCN1, as targets of miR-191 and miR-425. Finally, in vitro and in vivo experiments demonstrated that miR-191 and miR-425 reduced proliferation, impaired tumorigenesis and metastasis, and increased expression of epithelial markers in aggressive breast cancer cells. Our data provide compelling evidence for the transcriptional regulation of the miR-191/425 cluster and for its context-specific biological determinants in breast cancers. Importantly, we demonstrated that the miR-191/425 cluster, by reducing the expression of an extensive network of genes, has a fundamental impact on cancer initiation and progression of breast cancer cells.

MicroRNAs are small noncoding RNAs that act as posttranscriptional repressors of gene expression. A pivotal role for miRNAs in all the molecular processes driving initiation and progression of various malignancies, including breast cancer, has been described. Divergent miRNA expression between normal and neoplastic breast tissues has been demonstrated, as well as differential miRNA expression among the molecular subtypes of breast cancer. Over half of all breast cancers overexpress ERα, and several studies have shown that miRNA expression is controlled by ERα. We assessed the global change in microRNA expression after estrogen starvation and stimulation in breast cancer cells and identified that miR-191/425 and the host gene DALRD3 are positively associated to ERα-positive tumors. We demonstrated that ERα regulates the miR-191/425 cluster and verified the existence of a transcriptional network that allows a dual effect of estrogen on miR-191/425 and their host gene. We show that estrogen induction of miR-191/425 supports in vitro and in vivo the estrogen-dependent proliferation of ERα positive breast cancer cells. On the contrary, miR-191/425 cluster reprograms gene expression to impair tumorigenicity and metastatic potential of highly aggressive ERα negative breast cancer cells.

Applications of ambulatory blood pressure monitoring in clinical practice

Traditionally, blood pressure has been measured by the sphygmomanometer in the medical office. There is growing evidence, however, that office blood pressures may not be typical of values throughout the day. Between 20% and 30% of patients diagnosed with hypertension in the office actually are normotensive at other times. Ambulatory blood pressure monitoring with small, portable devices that automatically measure blood pressure every few minutes throughout the day appears to be an appropriate tool when "white-coat" hypertension is suspected--i.e., for individuals whose hypertension in the physician's office is not associated with other physical or historical evidence for cardiovascular disease or with other risk factors. Used prudently, ambulatory monitoring is a cost-effective technique that potentially can prevent unnecessary treatment of patients. Moreover, whole-day measurements may correlate more closely than office measurements may correlate more closely than office measurements do with findings of cardiovascular disease. This new approach also has highlighted the circadian pattern of blood pressure, especially the sharp early to mid-morning increase that coincides with an increased tendency to major cardiovascular events. This has focused attention on directing antihypertensive therapy towards the morning hours. Ambulatory monitoring is now used routinely in studies of antihypertensive drugs. This technique has no placebo effect and takes fewer patients to assess drug efficacy than do conventional methods.

Applications of ambulatory blood pressure monitoring in clinical practice

Traditionally, blood pressure has been measured by the sphygmomanometer in the medical office. There is growing evidence, however, that office blood pressures may not be typical of values throughout the day. Between 20% and 30% of patients diagnosed with hypertension in the office actually are normotensive at other times. Ambulatory blood pressure monitoring with small, portable devices that automatically measure blood pressure every few minutes throughout the day appears to be an appropriate tool when "white-coat" hypertension is suspected--i.e., for individuals whose hypertension in the physician's office is not associated with other physical or historical evidence for cardiovascular disease or with other risk factors. Used prudently, ambulatory monitoring is a cost-effective technique that potentially can prevent unnecessary treatment of patients. Moreover, whole-day measurements may correlate more closely than office measurements may correlate more closely than office measurements do with findings of cardiovascular disease. This new approach also has highlighted the circadian pattern of blood pressure, especially the sharp early to mid-morning increase that coincides with an increased tendency to major cardiovascular events. This has focused attention on directing antihypertensive therapy towards the morning hours. Ambulatory monitoring is now used routinely in studies of antihypertensive drugs. This technique has no placebo effect and takes fewer patients to assess drug efficacy than do conventional methods.

Antihypertensive dose-response relationships: studies with the selective alpha 1-blocking agent terazosin

Terazosin is a selective alpha 1-adrenergic-blocking agent indicated for the treatment of hypertension. The aim of this multicenter study, performed in 256 patients with mild to moderate essential hypertension, was to define the dosing characteristics of terazosin (in the range of 1 to 80 mg) administered once daily. Patients were randomly assigned to placebo or active treatment groups; each group received 3 months of treatment, which comprised three ascending doses of terazosin, each administered for a 1-month period. As determined by conventional office measurements of supine diastolic blood pressure and by automated ambulatory blood pressure monitoring, there was a clear antihypertensive dose-response relationship for terazosin in the range of 1 to 5 mg daily. Except for the 80 mg dose, none of the doses above 5 mg (10 to 40 mg) appeared to provide additional efficacy. Both the office measurements and the monitoring data indicated that the ratio of trough (effect at the end of the dosing interval) to peak (maximum effect during the dosing interval) was at least 50% or greater during treatment with the 5 mg dose. Thus the 5 mg dose appeared to provide meaningful clinical antihypertensive efficacy and to sustain its effects throughout the full 24-hour period.

Antihypertensive effects of beta-blockers administered once daily: 24-hour measurements

Whole-day automated ambulatory blood pressure (BP) monitoring was used to assess the duration of the antihypertensive actions of the beta-blockers atenolol (50 to 100 mg; n = 20) and acebutolol (400 to 800 mg; n = 19) each given once daily at 9 AM. When compared with its pretreatment 24-hour average, atenolol decreased diastolic BP by 10 +/- 2 mm Hg (p less than 0.01) and systolic BP by 12 +/- 2 mm Hg (p less than 0.01). Acebutolol decreased the 24-hour diastolic BP by 11 +/- 1 mm Hg (p less than 0.01) and systolic BP by 13 +/- 2 mm Hg (p less than 0.01). More specifically, a comparison of the two drugs during the final 6 hours (3 AM to 9 AM) of the dosing interval showed that the mean decrease in diastolic BP of 10.2 +/- 1.5 mm Hg with acebutolol was greater (p less than 0.05) than the decrease of 6.2 +/- 1.3 mm Hg with atenolol. Moreover, this final 6-hour effect of atenolol was less (p less than 0.01) than that observed during the first 18 hours of the day. The late effects of acebutolol did not change significantly from its early effects. The two agents also differed in their trough (final 2-hour decrease in diastolic BP) and peak (maximum 2-hour decrease in diastolic BP) effects: for atenolol the peak-to-trough difference was 7.8 +/- 3.1 mm Hg (p less than 0.05), whereas for acebutolol it was 3.8 +/- 4.2 mm Hg (N.S.). This study confirms the efficacy of atenolol and acebutolol.(ABSTRACT TRUNCATED AT 250 WORDS)

P-wave configuration as an indicator of echocardiographic indices of cardiac structure and function in normotensive adolescents

We evaluated the associations of a bimodal P-wave in ECG lead V1 to cardiac structure and function in healthy normotensive adolescents. Two-dimensional-guided M-mode echocardiography, 12-lead ECG, and conventional and 2-hour averaged automated blood pressure (BP) measurements were obtained in 40 normotensive (conventional BP less than 140/90 mm Hg) adolescents (mean age, 13 +/- 1 years). Compared with subjects with simple unimodal P-waves (n = 18), those with a normal yet bimodal P-wave in lead V1 (n = 22) had higher two-hour averaged systolic BP (108 +/- 12 mm Hg vs 99 +/- 7 mm Hg, p less than 0.01) and conventional sphygmomanometer systolic BP (110 +/- 11 mm Hg vs 103 +/- 10 mm Hg, p = 0.05). Structurally, the bimodal P-wave group had greater left ventricular mass (174 +/- 40 g vs 144 +/- 26 g, p less than 0.01), and functionally, they had a greater stroke volume (68 +/- 15 ml vs 57 +/- 13 ml, p less than 0.05) than the unimodal P-wave group. In the group with bimodal P-waves, left atrial size was directly related to left ventricular mass (r = 0.63). By step-wise multiple linear regression analysis, this correlation coefficient increased to 0.74 with inclusion of heart rate and to 0.82 with inclusion of systolic BP. Although left atrial size was similar in the unimodal and bimodal P-wave groups, it was unrelated to any parameter in the unimodal P-wave group. Thus, a bimodal P-wave in lead V1, while generally considered a normal variant, is associated with slightly higher systolic BP, significantly greater left ventricular mass, and greater stroke volume. Additionally, a bimodal P-wave in V1 is predictive of the parameters that influence left atrial size, especially left ventricular mass. While all of these findings fall within the traditionally defined normal ranges, the existence of a bimodal P-wave might identify young individuals who are vulnerable to early cardiovascular manifestations of hypertension.

Acute pharmacokinetic and hemodynamic effects of intravenous bolus dosing of nicardipine

The antihypertensive effects, duration of action, and pharmacokinetics of intravenous bolus doses of nicardipine were investigated in a series of patients with mild-to-moderate hypertension. Patients with a supine diastolic blood pressure between 95 and 114 mm Hg and a heart rate less than 90 beats/min who received no other antihypertensive medications were included in the study. On separate study days, single intravenous bolus doses of 0.125, 0.25, 0.5, 1, 3, 5, and 7 mg of nicardipine were administered over a 2-minute period. Blood pressure and heart rate were measured for 6 hours after an intravenous bolus of nicardipine was given, and serum nicardipine levels were measured throughout the study. Although the antihypertensive effect occurred immediately during the bolus infusion, peak average decreases in systolic and diastolic pressure ranged from 20 to 25 and 15 to 44 mm Hg, respectively, and occurred 2.5 +/- 0.6 minutes after infusion. Heart rate increased by 12 to 40 beats/min during the peak effect. The mean duration of action after an intravenous bolus dose was 24 +/- 5 minutes. A dose-response relationship was observed, as both nicardipine dosage and plasma nicardipine concentration correlated with reduction in blood pressure. These data indicate that bolus administration of nicardipine may provide a practical approach for the rapid parenteral treatment of hypertensive states.

Intravenous nicardipine for the treatment of severe hypertension. A double-blind, placebo-controlled multicenter trial

A placebo-controlled, double-blind multicenter trial was conducted in 123 patients with severe hypertension to examine the efficacy and safety of intravenously administered nicardipine hydrochloride in controlling blood pressure. Seventy-three patients were initially randomized to receive nicardipine treatment. This group had an initial blood pressure of 213 +/- 3/126 +/- 2 mm Hg. Sixty-seven patients achieved the therapeutic goal (diastolic blood pressure less than or equal to 95 mm Hg; systolic blood pressure less than or equal to 160 mm Hg). Fifty patients were randomized to receive placebo solution. Blood pressure in these patients was 216 +/- 3/125 +/- 2 mm Hg. No patient in this group achieved the therapeutic goal during the "blinded" portion of the study. Forty-four of 49 patients who did not respond to placebo administration responded to subsequent treatment with nicardipine. Patients with end-organ damage were included in the study. These included patients with left ventricular hypertrophy, retinopathy, and renal insufficiency. Patients with and without end-organ damage responded equally well to nicardipine treatment. Serious adverse experiences were infrequent, the most common adverse reaction being headache in 24% of the patients studied.

Assessing duration of antihypertensive effects with whole-day blood pressure monitoring

The whole-day blood pressure response to once-daily and twice-daily administration of a combination of captopril and hydrochlorothiazide was measured in a study of elderly patients (aged 59 to 78 years) with mild to moderate hypertension. Whole-day automated ambulatory blood pressure profiles were obtained at baseline, after 8 weeks of therapy with a combination of 25 mg of captopril and 15 mg of hydrochlorothiazide twice daily, and again after 8 weeks of once-daily therapy with 50 mg of captopril and 25 mg of hydrochlorothiazide. Average systolic and diastolic whole-day blood pressures significantly decreased from baseline during both twice-daily treatment (mean +/- SEM change, 18 [+/- 3]/10 [+/- 2] mm Hg) and once-daily treatment (11 [+/- 2]/9 [+/- 1] mm Hg). While the decrease in systolic blood pressure during once-daily therapy was less than that during twice-daily therapy for the group as a whole, 16 of 19 patients achieved normal systolic (less than 140 mm Hg) and diastolic (less than 90 mm Hg) blood pressures throughout the day during the once-daily regimen. During once-daily therapy, the blood pressure reductions were sustained throughout the 24-hour period, and were not attenuated during the final 2 to 4 hours before the next dose. A subgroup of 5 patients were identified who appeared unresponsive to both twice-daily and once-daily antihypertensive treatment. Despite hypertensive office-measured blood pressures at entry to the study, 4 of these 5 patients actually had normotensive whole-day blood pressure averages at baseline (mean, 131 [+/- 7]/81 [+/- 4] mm Hg). Thus, whole-day ambulatory blood pressure monitoring is a valuable tool for testing treatment responses. It demonstrated that once-daily treatment with low doses of captopril and hydrochlorothiazide was as effective as twice-daily administration in decreasing diastolic pressures throughout the day, but was slightly less effective in decreasing systolic pressures. Additionally, the monitoring identified apparently normotensive patients in whom treatment may not be indicated.

Comparison of antihypertensive therapies by noninvasive techniques

We compared the antihypertensive effects of the beta-blocker atenolol and the converting enzyme inhibitor lisinopril during 12 weeks of treatment in patients with mild to moderate essential hypertension. Atenolol (n = 10) significantly decreased conventionally measured blood pressure from 144/103 to 135/93 mm Hg and lisinopril (n = 9) from 150/104 to 130/92 mm Hg. Based on data derived from automated 24-h ambulatory blood pressure monitoring, atenolol decreased the average whole-day systolic pressure by 18 +/- 6 mm Hg (p less than 0.02) and the diastolic pressure by 11 +/- 2 mm Hg (p less than 0.01). Lisinopril produced decreases of 27 +/- 5 mm Hg (p less than 0.01) and 13 +/- 2 mm Hg (p less than 0.001). Examination of the 24-h blood pressure patterns showed that the efficacies of the two drugs were similar. Each appeared to be effective throughout the whole-day monitoring period, although only lisinopril significantly decreased blood pressure during the final four-h period (4 AM to 8 AM) preceding the next day's dose. Neither drug produced significant echocardiographic changes in left ventricular wall thickness or muscle mass during the short-term treatment. Lisinopril and atenolol effectively decrease blood pressure during a 24-h period. Moreover, we found that automated whole-day blood pressure monitoring is a useful tool for comparing the efficacy and duration of action of differing antihypertensive agents.

Hypertension in the aged: a pathophysiologic basis for treatment

According to major surveys, hypertension is found in over half the population aged 65 years or over. In this age group, systolic blood pressure is at least as important as diastolic blood pressure as a predictor of cardiovascular morbidity and mortality. Overall, the presence of hypertension is associated with approximately a threefold increase in the likelihood of major events. Differing factors contribute to the hypertension. Loss of proximal arterial compliance, affecting the larger conduit vessels, occurs often with aging and explains the tendency for systolic pressure to increase while diastolic pressure remains constant or even decreases. A loss of baroreceptor sensitivity also may contribute to hypertension. There is an increase in responsiveness of the sympathetic nervous system and an enhanced sensitivity to its effects in the elderly, perhaps reflecting a decline in the buffering activity of peripheral vascular beta receptors. It is possible, too, that sodium retention may contribute to hypertension in some older patients. Although diuretics traditionally have been the mainstay of treatment in these patients, it is now recognized that other classes of antihypertensive agents may be equally as effective yet less prone to metabolic or symptomatic adverse events. Sympatholytic drugs, calcium channel blockers and angiotensin-converting enzyme inhibitors, either as monotherapy or in combination with low-dose diuretics, have been shown to be efficacious in the elderly. These agents also can produce regression of left ventricular hypertrophy, an additional property that may contribute to a reduction in serious cardiac complications.

Mild hypertension in the elderly. A comparison of prazosin and enalapril

In a single-blind, crossover study, prazosin and enalapril monotherapies were evaluated in 15 patients, aged 55 years or older (average age, 64 years), with mild hypertension (sitting diastolic blood pressure between 90 and 104 mm Hg). After eight weeks of placebo administration, patients were randomly assigned to treatment with prazosin or enalapril and then treated with the alternate drug after a second eight-week placebo washout period. The dose was titrated from 1 mg to a maximum of 10 mg twice daily of prazosin and from 2.5 mg to a maximum of 20 mg twice daily of enalapril to achieve a reduction in diastolic blood pressure to less than 85 mm Hg, with a decrease of at least 10 mm Hg based on clinical measurements of blood pressure. Patients received maintenance therapy with each medication for at least eight weeks. The response to therapy was then evaluated with two-hour periods of automated blood pressure monitoring. Average systolic and diastolic blood pressures for all patients during these two-hour monitoring periods decreased by 10.3 +/- 1.9/8.3 +/- 1.5 mm Hg during prazosin therapy and by 9.0 +/- 5.1/5.8 +/- 3.4 mm Hg during enalapril therapy. All patients responded to one of the two drugs, but only 50 percent responded to both. Side effects were generally mild and transient, and no significant metabolic effects were observed. Both prazosin and enalapril were effective and well tolerated in this population of elderly patients with mild hypertension.

Validation of portable noninvasive blood pressure monitoring devices: comparisons with intra-arterial and sphygmomanometer measurements

We have evaluated the accuracy of measurements provided by different types of portable automatic blood pressure monitoring devices by comparing them with intra-arterial and mercury sphygmomanometer measurements in 25 hospitalized patients. Systolic blood pressure values with portable devices that use auscultatory or oscillometric methods of measurement correlated significantly with intra-arterial values (r = 0.74 and 0.89; p less than 0.001 for both); similarly, diastolic values correlated significantly (r = 0.86 and 0.81; p less than 0.001 for both). Compared with intra-arterial measurements, there was a slight tendency for the portable devices to underestimate systolic blood pressure and overestimate diastolic blood pressure. Correlations between auscultatory or oscillometric measurements and sphygmomanometer measurements in these patients were also significant; moreover, the absolute blood pressure values obtained with the portable devices were almost identical to those with the sphymomanometer. In a further group of 12 volunteers, auscultatory and oscillometric values correlated very closely with simultaneously measured sphygmomanometer values for both systolic (r = 0.99 and 0.98) and diastolic (r = 0.96 and 0.94) blood pressures. An auscultatory device that uses continuous ECG R wave gating for Korotkoff sounds was also found to be highly accurate. Thus we have found that automated portable devices that use either auscultatory or oscillometric methods of measurement provide reliable blood pressure values.

Characterization of antihypertensive therapy by whole-day blood pressure monitoring

Whole-day ambulatory monitoring is used for diagnosing hypertension and for judging response to treatment. We evaluated both of these properties in an antihypertensive trial with the calcium channel blocker diltiazem hydrochloride. Measured by a conventional sphygmomanometer, systolic and diastolic blood pressures fell significantly in patients who received diltiazem, whereas no consistent changes occurred in those who received placebo. Administration of the drug also decreased systolic and diastolic blood pressures evenly throughout the day, as determined by automated monitoring. The 15 diltiazem-treated patients were subdivided into those whose clinically diagnosed hypertension was confirmed by pretreatment blood pressure monitoring (24-hour average diastolic blood pressure, greater than or equal to 90 mm Hg; n = 9) and those whose 24-hour blood pressures failed to meet this criterion (n = 6). Diltiazem therapy decreased average whole-day blood pressures by 18/13 mm Hg in the hypertensives but by only 0/1 mm Hg in the others. Thus, whole-day blood pressure monitoring strengthens antihypertensive trials by documenting efficacy and duration of treatment. In addition, it enhances the diagnosis of hypertension, thereby identifying those patients in whom treatment seems justified.