Nutritional and lifestyle approaches to the prevention and management of hypertension

We have been encouraged by the growing interest in nutrition and lifestyle for the prevention and treatment of hypertension. While no proven means for preventing hypertension exist, epidemiologic data have identified risk factors for hypertension. We have attempted to outline a reasonable program based on knowledge of risk factors for hypertension on one hand vs. the lack of data that hypertension can be prevented on the other. Managing patients who have hypertension with nondrug strategies is a different matter. First, more evidence is available indicating effectiveness for reducing a high pressure than for preventing a normotensive person from becoming hypertensive. Secondly, hypertension is a risk factor for premature cardiovascular morbidity and mortality. Thus, the risk-to-benefit ratio from intervening is tipped toward probability of benefit. Many of the nondrug therapies have been presented. It is unreasonable to expect a patient to adhere to every one. Therefore, patients with uncomplicated, newly diagnosed borderline and mild hypertension are given the range of modalities available and assisted in choosing those best suited to their lifestyle. The nondrug efforts are tried for three to six months in patients with uncomplicated mild hypertension. We advocate evaluating responses to the nondrug approaches with blood pressures measured both in and outside the office. Blood pressures measured by the patient at work and rest have been very valuable in our practice. If no antihypertensive benefit is seen, then most of these patients receive standard antihypertensive drugs. For those who have complete or partial success, the nondrug efforts are continued or reinforced with follow-up every three to six months.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular hypertrophy in borderline hypertension: relationship to blood pressure and sympathetic drive

While borderline hypertension increases the chance for cardiovascular disease, most with borderline hypertension will not experience problems. Thus, the risk of intervening probably outweighs benefit for the majority. However, those with target organ damage are probably at higher risk and might benefit from more aggressive management. Therefore, we assessed vascular hypertrophy and average home blood pressures in patients with borderline hypertension which might be of value in therapeutic planning. Minimum forearm vascular resistance (mFAVR) was used as an index of vascular hypertrophy. Comparing ten normotensive controls to twenty individuals with borderline hypertension revealed a significant difference in mFAVR (1.7 +/- 0.06 vs 2.1 +/- 0.1, p less than .05). There were obvious differences in blood pressure between normotensives and borderlines which contributed to differences in mFAVR. However, within the group with borderline hypertension, no relationship was apparent between mean blood pressure and mFAVR, r = 0.13, NS. Among the borderline hypertensives, baseline plasma norepinephrine correlated with mFAVR, r = 0.48, p less than .05, suggesting that the sympathetic nervous system contributes to vascular hypertrophy in this group. In a separate group of individuals with nine normotensives and nine borderline hypertensives we wished to find if average home blood pressure would correlate better with mFAVR than a single laboratory measurement. While both the home (r = 0.56, p less than .05) and laboratory (r = 0.66, p less than .01) MBP correlated significantly with mFAVR, the data did not confirm the hypothesis that the average home blood pressures would better predict the degree of vascular hypertrophy. These data show that a substantial proportion of patients with borderline hypertension have evidence for vascular hypertrophy, sympathetic drive might contribute to vascular hypertrophy in borderline hypertension, average home blood pressures did not aid in separating those with and without evidence for vascular hypertrophy.

Role of cardiopulmonary mechanoreceptors in ADH release in normal humans

Although animal studies have shown that cardiopulmonary receptors regulate the release of antidiuretic hormone (ADH), human studies have produced conflicting results. Consequently, we studied 17 normal healthy men to determine the ADH response to selective unloading (decreased stretch) of cardiopulmonary low-pressure receptors by thigh cuff inflation in the supine position. Thigh cuff inflation of 30 to 40 mm Hg decreased the central blood volume and right atrial pressure (cardiopulmonary receptor load), while mean arterial pressure and pulse pressure were unchanged (arterial baroreceptor load). Thigh cuff inflation to this level did not alter plasma osmolality or cardiac output. Plasma ADH increased an average of 67% (p less than 0.01) following thigh cuff inflation compared to the preceding supine baseline. After thigh cuff deflation (n = 6), the ADH decreased toward preinflation values. We conclude that selective unloading of the cardiopulmonary receptors in humans increases plasma ADH levels.

Cardiopulmonary mechanoreceptors and renin release in humans

We investigated the hemodynamic determinants of the reflex release of renin to changes in posture and blood volume distribution in healthy humans to determine the relative contribution of arterial and cardiopulmonary mechanoreceptors to the reflex release of renin under physiological circumstances. In the first experiments, we induced a selective decrease of right atrial pressure by inflation of cuffs around the thighs. Renin increased and returned toward baseline on decompression. The renin increase was neurogenic because plasma norepinephrine increased, the response was abolished by beta blockade, and renin did not increase in patients with denervated transplanted kidneys. The second experiments were performed with tilting and later filling a pressure suit to counteract the effect of tilting on gravitational pooling of the blood. Tilting elicited increases of renin and norepinephrine; filling the suit abolished these increases. Right atrial pressure fell with tilting and rose after filling the suit. Because the neck was elevated above the heart equally in both conditions, it is concluded that the increase and decrease of renin reflected decrease and increase of the stretch of cardiopulmonary receptors. The third experiments were performed by elevating the upper trunk with the legs remaining in a horizontal position (sitting). This caused a heart-to-neck pressure difference and an increased sympathetic outflow through unloading arterial baroreceptors. Norepinephrine increased but renin did not. Cardiopulmonary receptors exhibit an important influence on the reflex release of renin.

Borderline hypertension

Blood pressures over 130 mm Hg systolic and 80 mm Hg diastolic are associated with a significantly increased risk of cardiovascular morbidity and mortality as well as an increased risk of progression to later established hypertension. An average blood pressure based on repeated determinations is a better predictor of target organ damage in hypertensive individuals than an isolated casual clinic blood pressure. Careful clinical assessment of the patient with borderline hypertension can identify those at highest risk for progression to established hypertension and those at greatest risk for cardiovascular morbidity and mortality. We cannot currently recommend pharmacologic therapy for the vast majority of patients with blood pressures between l30/80 and l140/90 mm Hg. Although nonpharmacologic therapy is frequently met with a high degree of noncompliance, there is evidence that modest reductions in salt intake and weight often result in significant reductions in blood pressure. Many patients with borderline hypertension, when appraised of these facts, will comply and attempt to reach these limited goals. Repeated self-determination of blood pressures at home is ideally suited to many patients with borderline hypertension in defining current average blood pressure, detecting future progression, and evaluating the effects of nonpharmacologic interventions.

The transient inability of the conjugating female cell to host 186 infection explains the absence of zygotic induction for 186

In an Hfr(186) X F- cross, the 186 prophage on the incoming male chromosome is not induced, despite the fact that prophage 186 can be induced by other means (W. H. Woods and J.B. Egan, J Virol. 14:1349-1356, 1974). We show here that the conjugating female is temporarily inhibitory to infection by 186, and this delay, we postulate, enables cI repression to be reestablished before the female cell recovers its 186 sensitivity.

Coliphage 186 Replication is delayed when the host cell is UV irradiated before infection

In contrast to results with injections by lambda and P2, the latent period for infection by coliphage 186 is extended when the host cell is UV irradiated before infection. We find that 186 replication is significantly delayed in such a cell, even though the phage itself has not been irradiated. In contrast, replication of the closely related phage P2 under the same conditions is not affected.

A preliminary report of mortality patterns among foundry workers

A proportional mortality study was conducted utilizing the death records maintained from 1971 to 1975 by the International Molders and Allied Workers Union as part of a death benefits program. Death certificates were obtained on 3,013 members of the study group and classified according to the 8th Revision of the ICA by a trained nosologist. The ate- and race-specific cause distribution of all deaths among males in the United States for 1973 were used as a standard from which expected deaths were calculated. The statistical significance of differences between observed and expected numbers of deaths was determined by a chi-square test. The most statistically significant finding in this study was an excess lung cancer mortality (208 observed vs. 142 expected) and an excess mortality due to pneumoconiosis (29 observed vs. 5 expected). A discussion is included of the potential agents found in the foundry environment that may be responsible for the increased lung cancer risk.

Pneumomediastinum and diabetic hyperpnoea

Images