A phase I trial of alpha-interferon in combination with pentostatin in hematologic malignancies

Pentostatin, a novel inhibitor of adenosine deaminase, has shown activity in various lymphoid malignancies of both the T and B cell lineage. This agent has unique side effects and in general myelosuppression has been mild. Interferon has both antiviral and antineoplastic properties. This agent has shown activity in hairy cell leukemia, chronic granulocytic leukemia, low grade lymphoma, and myeloma. Side effects from interferon are in general dissimilar to those that have been seen with pentostatin and in particular myelosuppression has not been a major toxicity with low doses of interferon. This current trial explored the combination of pentostatin and interferon in hematologic malignancies. Fifteen patients were enrolled in this phase I trial at a fixed dose of pentostatin of 4 mg/m2 biweekly and interferon at doses of 0.5, 1, 2, or 4 million units/m2 of interferon. At the first three dose levels of interferon nausea and vomiting were the predominant toxicity and appeared to worsen with time on study. Fatigue also was seen at the lowest level of interferon and was severe enough to cause two individuals to discontinue the study medications. At higher dose levels of interferon, myelosuppression, nausea and vomiting, and fatigue were the predominant toxicities. One patient with hairy cell leukemia had a complete response and a second patient with T cell cutaneous lymphoma had a partial response which lasted for 6 to 7 weeks. The maximum tolerated dose of interferon with pentostatin in this patient population was four million units/m2.

Pharmacokinetics of carvedilol in older and younger patients

Carvedilol, a combined beta- and alpha 1-blocking drug, was given to 8 young (age 39-47) and 21 old (age 64-79) patients with essential hypertension. Clinical and pharmacokinetic responses to 12.5, 25 and 50 mg were determined and compared. In both age groups, pharmacokinetic data were similar with all three doses of carvedilol. Peak blood levels were reached within 90 minutes and at 24 hours the trough blood level was less than 10% of the peak level. Carvedilol or its metabolite did not accumulate. Falls in systolic and diastolic BP were greater than 7 mmHg in 28 of the 29 patients. The falls in diastolic BP did not differ between groups but the older group had a greater fall in systolic BP. However, the systolic BP of the older group was higher and expressed as a percentage, the falls in BP did not differ. The time to peak fall in BP was about 4 hours and was always after the time to peak blood level. There was no correlation between blood level and BP fall. When the drug was administered 24 h after the previous dose, a further fall in BP was seen indicating a greater effect at peak drug levels. Side effects were few and, during the chronic study, there was no postural hypotension or postural hypotensive symptoms. On the study days, five patients developed postural hypotension with symptoms. These were not observed at other times and may have been due to decreased sympathetic outflow on the study days. Carvedilol lowered BP in order and younger patients. There were no significant effects of age on its pharmacokinetics. Carvedilol is an effective antihypertensive agent that can be used in people with essential hypertension in all age groups.

Effect of portal hypertension on in vivo bile acid-mediated small intestinal mucosal injury in the rat

This study's purpose was to determine whether portal hypertension adversely affects small intestinal mucosal injury. Portal hypertension was produced in male Sprague-Dawley rats by two-stage ligation of the portal vein. Sham-operated rats were used as controls. Two weeks later, intestinal injury was produced by in vivo perfusion with 5 mM chenodeoxycholic acid for 30 min. Intestinal injury was assessed by quantitative morphometry and by measuring intestinal water and mannitol absorption. Portal hypertension resulted in more injury in the distal perfused intestine as manifested by increased villus tip denudation [portal hypertensive 52.5 +/- 9.6 (SEM) vs controls 28.1 +/- 5.7 microns, P = 0.05). Additionally there was a significant decrease in the unperfused duodenal villus height in portal hypertensive rats (portal hypertensive 755 +/- 22 vs controls 848 +/- 28 microns, P less than 0.02). Portal hypertension had no significant effect on the increase in mannitol absorption or water secretion caused by chenodeoxycholic acid perfusion. This study suggests that portal hypertension alters small intestinal mucosa and increases susceptibility to injury.

Simvastatin in the treatment of hypercholesterolaemia in patients with essential hypertension

Mortality from coronary artery disease is a common problem in treated hypertensive patients, and these people have a high prevalence of elevated cholesterol levels. A study was undertaken to determine whether cholesterol could be lowered effectively without major side effects in patients with treated hypertension. Forty-nine patients (mean age 67.6 years) with cholesterol greater than 5.5 mmol/l were placed on a reduced-fat (less than 30% of calories from fat with a ratio of polyunsaturated to saturated fats of less than 1) diet for 3 months. If the cholesterol was between 5.5 and 7.5 mmol/l and total cholesterol divided by high-density lipoprotein cholesterol was greater than 4.5, the patients were randomly allocated either to the simvastatin (24 patients) or the placebo group (25 patients). Diet and placebo caused minor and insignificant falls in cholesterol and no change in triglycerides or lipids. Treatment with simvastatin reduced cholesterol levels from 6.85 to 4.75 mmol/l (P less than 0.001), triglycerides from 2.7 to 2.1 mmol/l (P less than 0.01), low-density lipoproteins from 4.6 to 2.6 mmol/l (P less than 0.001) and high-density lipoproteins rose from 1.09 to 1.18 mmol/l (P less than 0.01). Total cholesterol divided by high-density lipoprotein cholesterol fell from 6.3 to 4.0 (P less than 0.001). The drug was well tolerated and the side-effect profile did not differ from the placebo in clinical or biochemical events. The active drug was stopped in one patient (abdominal pain, dizziness, headache, tiredness) and in two patients taking the placebo (elevated creatine phosphokinase, cardiovascular collapse). Simvastatin effectively lowered total cholesterol and improved the lipoprotein profile. The dose required in most patients was 40 mg/day. Simvastatin may be an acceptable drug to improve the lipoprotein profile in order to determine whether this improves the prognosis in patients treated for hypertension.

Interaction of enalapril with sodium restriction, diuretics, and slow-channel calcium-blocking drugs

While monotherapy sometimes controls blood pressure (BP), it is often essential to add a second drug for adequate control. This study examined in a factorial fashion the interaction of enalapril with some commonly used antihypertensive therapies. There were between 10 and 16 patients in each study, and the patients had responded in part to the two drugs used. Enalapril and sodium restriction lowered BP 12 +/- 3/11 +/- 2 and 4 +/- 2/3 +/- 1 mm Hg, respectively. The effects of the two therapies were additive, and there was no interaction. Enalapril and hydrochlorothiazide lowered BP 11 +/- 3/8 +/- 3 and 8 +/- 2/6 +/- 2 mm Hg, respectively. The effect of the two drugs together indicated a positive interaction of 4 +/- 2/3 +/- 1 mm Hg (p less than 0.05). Enalapril and nifedipine both lowered BP (10 +/- 2/8 +/- 1 and 11 +/- 3/8 +/- 1 mm Hg). The two drugs combined had a strongly positive interaction of 10 +/- 3/7 +/- 2 mm Hg (p less than 0.001). Enalapril can be used with the other therapeutic methods tested. If a converting enzyme inhibitor does not reduce BP adequately, it appears appropriate to add a thiazide diuretic or a slow-channel calcium-blocking drug. The mechanism of the positive interaction with diuretics probably reflects an effect on the renin-angiotensin system, but the explanation for the synergism with slow-channel calcium-blocking drugs is unclear.

Effect of mineralocorticoids and salt loading on renin release, renal renin content and renal renin mRNA in mice

1. DOCA and 9 alpha-fludrocortisone were given to mice on a high-sodium diet for periods of up to 20 weeks, resulting in decreases in plasma renin concentration, renal renin concentration and renal renin mRNA with both treatments. 2. Plasma renin concentration was suppressed prior to suppression of renin mRNA and renal renin levels, indicating that suppression of synthesis and secretion of renin occur separately. 3. The decrease in renal renin concentration that occurred with DOCA was greater and more rapid than the decrease that occurred with 9 alpha-fludrocortisone, suggesting that DOCA caused intra-renal breakdown of renin. 4. When DOCA was given to mice on a low-sodium diet, plasma renin concentration and renal renin concentration increased, indicating that the effects of DOCA on renin levels were dependent on dietary sodium. 5. Renin secretion and synthesis appeared to be controlled by different mechanisms and sodium balance has an important effect on both processes.

Modulation of the metabolism and pharmacokinetics of 1-beta-D-arabinofuranosylcytosine by 1-beta-D-arabinofuranosyluracil in leukemic mice

The interaction between high concentrations of 1-beta-D-arabinofuranosyluracil (HiCAU) and 1-beta-D-arabinofuranosylcytosine (ara-C) was investigated in vivo with emphasis on cell kinetics, pharmacokinetics, and drug metabolism. Mice bearing L5178Y leukemia were given a 48-h s.c. infusion of high-dose ara-U (HiDAU) to achieve a plasma level of 0.5 to 1 mM. A total dose of 7.35 g/kg/day for 2 days was nontoxic; the mean survival of control (saline treated) leukemic mice was 12.2 +/- 1.8 days and 11.7 +/- 2.0 days for the HiDAU-treated leukemic mice. Using flow cytometry, cell cycle progression of L5178Y ascites cells was monitored during HiDAU infusion. At 48 h, the proliferative index (PI) percentage of the leukemic cells is significantly different (P less than 0.001) in HiDAU-treated leukemic mice (mean = 50.8) versus control (mean = 45.6). A higher PI percentage is associated with accumulation of cells in S phase. This effect was highly variable in the ara-U-treated mice, and the ara-U "perturbed" group was defined as those mice whose cells had an increase in the PI to greater than or equal to 50%. The higher PI percentage in HiDAU-treated mice correlated with HiCAU in ascites fluid, leukemic cells, and kidney of perturbed mice. HiCAU in the "ara-U-perturbed" group altered the plasma pharmacokinetics of high-dose ara-C (HiDAC, 1 g/kg), increased the cellular metabolism of ara-C to 1-beta-D-arabinofuranosylcytidine triphosphate (ara-CTP) (3-fold), and increased ara-C-DNA synthesis (3-fold). In mice bearing the L5178Y leukemia, a 48-h infusion of ara-U followed by a 24-h s.c. infusion of 40 mg/kg resulted in a 260% increase in life span and seven 90-day survivors among 16 treated mice. In contrast, ara-U or ara-C alone had a negligible therapeutic effect. ara-U-induced alterations in the systemic pharmacokinetics of ara-C are the result of inhibition of cytidine deaminase activity by HiCAU in liver and kidneys. This results in a decrease in ara-C catabolism and prolongs the plasma half-life of ara-C. The dual alteration of the pharmacokinetics of ara-C and cytokinetics of the leukemia cells by HiCAU results in enhanced survival of leukemic mice. These results may help explain the clinical utility of HiDAC treatment programs for patients with acute leukemia.

Effect of calcium carbonate on blood pressure in normotensive and hypertensive people

Forty-seven patients with mild hypertension and 48 normotensive patients entered a blinded, parallel study in which they received a placebo, 10 mmol/day calcium carbonate (CaCO3), or 20 mmol/day CaCO3. There were no significant differences in blood pressure changes among the groups. In the hypertensive group and in patients with the highest blood pressure there were individual falls in systolic pressure, particularly in the group receiving 10 mmol daily CaCO3. In the hypertensive group the changes were: with placebo, -3 +/- 2/-2 +/- 2 mm Hg; with CaCO3 (10 mmol), -7 +/- 3/-2 +/- 2 mm Hg; and with CaCO3 (20 mmol), -2 +/- 3/1 +/- 2 mm Hg. No change was significant, and no pressure changes of patients taking CaCO3 differed significantly from changes of patients taking placebo. Ten of 33 patients taking placebo, 11 of 31 taking 10 mmol/day CaCO3, and nine of 31 taking 20 mmol/day CaCO3 were classified as responders from their systolic blood pressure fall. These response rates did not differ. Eight patients had falls of systolic blood pressure greater than 15 mm Hg. Five were on 10 mmol/day CaCO3 and three on 20 mmol/day CaCO3. This response was significantly different from that with placebo. Univariate analyses failed to reveal any predictive dietary or biochemical parameter. After 3 months of not taking CaCO3, 12 patients classified as responders, including six of the eight with a fall of 15 mm Hg or more, were rerandomized to placebo or to 20 mmol/day CaCO3. In the rechallenge, responses to CaCO3 and placebo were similar, neither causing a significant pressure fall. Calcium carbonate did not reduce blood pressure. The apparent response in a few patients was not verified by rechallenge. The present study does not support calcium supplementation as a useful nonpharmacological measure for reducing elevated blood pressure.

Interaction of slow-channel calcium blocking drugs with sodium restriction, diuretics and angiotensin converting enzyme inhibitors

The interactions of nifedipine with sodium restriction, diuretics and enalapril were studied using a 2 x 2 factorial design. Nifedipine lowered blood pressure to a greater extent than sodium restriction or hydrochlorothiazide. With both of these therapies there was a negative interactive term, which indicated that their combination had no greater effect than the use of nifedipine alone. Enalapril and nifedipine lowered blood pressure by 10 +/- 2/8 +/- 1 and 11 +/- 3/8 +/- 1 mmHg, respectively. The combination lowered blood pressure by 32 +/- 3/24 +/- 2 mmHg. The reasons for these negative and positive interactions are not clear, but may relate to interactions that regulate the availability of calcium for initiation of contraction in smooth muscle cells of the arterioles.

The effect of a rechallenge with CaCO3 in patients who have been classified as responders to an initial challenge

In a previous study 25 of 95 patients were identified as possibly having a fall in blood pressure with CaCO3 supplementation. After a 3-month period off calcium and on their usual diet, 12 of these were randomly assigned to receive placebo or CaCO3. Four crossed over to the alternate therapy after 2 months on the first agent. The change in blood pressure with placebo was 0.3 +/- 4.3/2.9 +/- 2.7 mmHg and the change in blood pressure with CaCO3 at 20 mmol/day was 1.3 +/- 4.8/-0.3 +/- 4.2 mmHg. These changes were not different from each other or from zero, and contrasted with the fall of 16.5 +/- 2.3/7.8 +/- 2.7 mmHg in the initial study. This study indicates that apparent individual falls in blood pressure with calcium supplementation need to be verified by rechallenge before such patients can be classified as responders. The absence of a predictable response, if applied to other studies, casts doubt on the conclusions made. Calcium supplementation cannot be recommended as a method of reducing blood pressure in people with mild hypertension.

Effect of pH on vasopressin-induced water permeability in collecting ducts of isolated rat papillae

1. The effects of basolateral and luminal pH on diffusional water permeability of microperfused collecting ducts of isolated rat papillae were examined in the presence and absence of vasopressin at two concentrations. 2. In the absence of vasopressin, collecting duct diffusional water permeabilities did not differ when the pH of the luminal fluid was varied. Similarly, in the absence of vasopressin, collecting duct diffusional water permeabilities did not differ when the bath pH was varied. 3. In the presence of 50 microU/ml vasopressin, increases in diffusional water permeability of collecting ducts perfused with solutions at pH 5.0, 7.4 or 9.0 did not differ significantly. Similarly, increases in diffusional water permeability induced by 200 microU/ml vasopressin were not different when collecting ducts were perfused with solutions at pH 5.0, 7.4 or 9.0. 4. The presence of vasopressin (50 microU/ml) in the bathing medium at pH 6.4, 7.4 and 8.4 induced increments in diffusional water permeability of 0.40 +/- 0.21 (n = 14, P greater than 0.05), 1.56 +/- 0.27 (n = 27, P less than 0.001) and 1.67 +/- 0.24 (n = 12, P less than 0.001) microns/s, respectively. The increment in water permeability at pH 6.4 was significantly less than that at pH 7.4 (P less than 0.001). 5. The presence of vasopressin (200 microU/ml) in the bathing medium at pH 6.4, 7.4 and 8.4 induced increments in diffusional water permeability of 2.16 +/- 0.54 (n = 9, P less than 0.01), 2.55 +/- 0.51 (n = 17, P less than 0.001) and 0.98 +/- 0.34 (n = 11, P less than 0.05) microns/s respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of atrial peptide on collecting duct function

1. The effects of synthetic rat atrial natriuretic peptides (ANP) on diffusional 22Na+, 36Cl- and tritiated water (THO) permeability of in vitro microperfused rat papillary collecting ducts and the effect in vivo of ANP on stop-flow sodium concentrations in the terminal segment of rabbit nephrons were studied. 2. The addition of 4 x 10(-8) or 4 x 10(-7) mol/l ANP to the medium or perfusion solution did not alter diffusional 22Na+ or 36Cl- permeability of microperfused rat papillary collecting ducts. 3. The basal diffusional THO permeability of papillary collecting ducts was not altered when 4 x 10(-7) mol/l ANP was present in the medium and did not inhibit the increment in diffusional THO permeability induced by vasopressin or reduce the permeability to water in a duct previously stimulated by vasopressin. 4. The administration of ANP (2 micrograms/kg bodyweight) to rabbits in water diuresis did not alter systemic blood pressure but induced a marked natriuresis and increases in urine flow and potassium excretion. This natriuresis was not associated with alterations in stop-flow sodium reabsorptive capacity or sodium permeability of the collecting tubules and ducts. 5. Previously reported in vivo clearance data suggest that ANP causes, at least in part, a natriuresis by altering sodium transport in the medullary collecting ducts. In this study, however, a direct effect could not be demonstrated and it is possible that the medulla needs to be functioning in its normal environment for such effects to be demonstrated.

Interaction in hypertensive man between sodium intake, converting enzyme inhibitor (enalapril), plasma renin and blood pressure control

Sixteen patients with hypertension entered a study in which the effects of enalapril were compared with sodium restriction, with the two in combination and with placebo using a balanced randomized double-crossover design. Each patient had four treatment phases of two weeks, duration which comprised a 2 x 2 factorial design as well as an initial period on sodium restriction and enalapril placebo. All patients received a reduced sodium diet and sodium intake was altered by slow Na tablets. Increasing sodium intake raised blood pressure similarly whether patients were receiving enalapril or its placebo. Enalapril lowered blood pressure to a similar extent in patients on either a low and high sodium intake. The combination of a low sodium intake and enalapril was additive and there was no interactive effect between the two therapies whether assessed by a linear or a logarithmic method. Plasma renin was increased by enalapril and lowered by increased sodium intake. These effects were additive and there was no interactive effect. Neither the initial plasma renin nor the rise in renin predicted which patients would respond to enalapril. Enalapril was an effective antihypertensive agent and its blood pressure-lowering effect and that of sodium restriction were additive.

Enalapril & nifedipine in essential hypertension; synergism of the hypotensive effects in combination

Twelve male hypertensive patients who had required enalapril and nifedipine to control their blood pressure were entered into a study of modified 2 x 2 factorial design (3 week study periods) to determine the effect of each drug separately and in combination. Factorial analysis indicated that enalapril alone (20 mg/d) lowered supine blood pressure by 10 +/- 2/8 +/- 1 mmHg, nifedipine alone (30 mg/d) lowered supine blood pressure by 11 +/- 2/8 +/- 1 mmHg and there was a positive interactive effect of 10 +/- 3/7 +/- 2 mmHg (P less than 0.001) such that the combination lowered supine blood pressure by 32 +/- 3/24 +/- 2 mmHg. The effects of the individual drugs were both significant (P less than 0.001) but did not differ from each other. Enalapril and nifedipine are both effective antihypertensive drugs and in some hypertensive patients their effects appear to be synergistic.

Significance of isolated antibody to hepatitis B core antigen determined by immune response to hepatitis B vaccination

The immune response to hepatitis B vaccine was studied in 14 individuals with isolated, high-titer antibody to hepatitis B core antigen (anti-HBc) and examined as an indicator of this serologic pattern's significance. Four subjects demonstrated a low-titer antibody to hepatitis B surface antigen (anti-HBs) on repeated testing, and three in this subgroup had anamnestic responses (anti-HBs, 82 to 140 ratio units) after vaccination. Compared with 22 seronegative controls, the remaining ten had significantly higher anti-HBs response rates (78% vs 22%, P = .003) and median anti-HBs titers (4 vs 0 ratio units, P = .008) two weeks after vaccination. One of ten subjects had an anamnestic response, while another exhibited no response. The general pattern of anti-HBs responsiveness observed in those subjects with isolated, high-titer anti-HBc was intermediate between seronegative and anti-HBs-positive groups and may indicate a state of waning immunity after natural infection. Hepatitis B vaccination with follow-up anti-HBs testing should be done for those patients with isolated, high-titer anti-HBc to help exclude chronic infection and boost protective immunity.

Reversal of benign intracranial hypertension by surgically induced weight loss

Weight loss is recommended in the treatment of benign intracranial hypertension (BIH) but is difficult to achieve because of the administration of steroids. A 24-year-old morbidly obese woman with BIH presented with headache, a cerebrospinal fluid pressure of 300 mm H2O, enlargement of the blind spot in the right eye, and bilateral papilledema. Treatment with steroids for one year produced an increase in weight with worsening symptoms and visual findings. Gastric exclusion surgery produced a 37-kg weight loss in six months that was associated with cessation of symptoms, reduction in cerebrospinal fluid pressure to 170 mm H2O, marked improvement in visual fields, and resolution of papilledema. This raises the possibility that gastric exclusion surgery may be an effective means to achieve weight loss and ultimately a remission in obese patients with BIH.

Sodium restriction can delay the return of hypertension in patients previously well-controlled on drug therapy

Sodium restriction can reduce blood pressure in hypertensive patients. The present study indicates that if hypertension is well controlled then the reemergence of hypertension can be decreased by the use of a reduced sodium intake. The present paper demonstrates that in such patients on a normal salt diet, 90% become hypertensive within 6 months while only 40% of people on a reduced sodium diet become hypertensive. It is proposed that a high sodium intake activates a number of amplifiers that causes a shift of the dose-response curve to sodium to the left and if not prevented or interrupted leads to the development of hypertension.

Immediate effects of furosemide on renal hemodynamics in chronic liver disease with ascites

Furosemide occasionally causes azotemia in patients with ascites, independently of induced volume depletion. To define this effect, we measured renal clearances in patients with chronic liver disease and ascites and in nonascitic controls. Furosemide (80 mg i.v.) transiently increased p-aminohippurate clearance in controls (from 693 +/- 67 to 928 +/- 93 ml/min) and in 11 patients with ascites (from 418 +/- 81 to 526 +/- 80 ml/min). In contrast, in 13 patients with ascites, p-aminohippurate clearance fell by 34% (from 545 +/- 51 to 360 +/- 24 ml/min) within 20 min and by 41% within 60 min, and inulin clearance fell by 19% at 20 min and by 30% at 60 min. The renal effects lasted approximately 4 h. The renal response could not be predicted by renin activity, urinary prostaglandin excretion, urinary sodium, or clinical characteristics. In all 14 patients who received oral furosemide, p-aminohippurate clearance fell within 90 min (by 24%) and remained suppressed for at least 4 h. These immediate effects of furosemide on renal perfusion may contribute to azotemia in some patients with ascites.

The effect of DOCA and 9 alpha-fludrocortisone on renal renin content and production

1. DOCA and 9 alpha-fludrocortisone were given to rats. 2. Plasma renin fell rapidly with both treatments. 3. Renal renin fell slowly to a low level. 4. Renal renin fell to a lower level with DOCA than with 9 alpha-fludrocortisone. 5. When DOCA and 9 alpha-fludrocortisone were stopped plasma renin levels rose rapidly and the renal renin levels increased. 6. The data suggest that synthesis is altered rapidly but it takes a prolonged time for the kidney to become depleted of renin due to the high tissue stores and the associated inhibition of release.

Effect of atrial natriuretic peptide on collecting duct function evaluated by stop-flow in rabbits

1. The effect of a low dose of a synthetic atrial natriuretic peptide (ANP), rat atriopeptin II (23 amino acids), on stop-flow sodium concentrations was examined in rabbits in water diuresis. 2. Atrial natriuretic peptide (2 micrograms/kg body weight) was injected intravenously as a bolus either before or after the commencement of stop-flow. 3. Atrial natriuretic peptide induced a significant natriuresis within 2 min of injection. This natriuresis was associated with smaller increases in urine volume and potassium excretion. Atrial natriuretic peptide did not alter blood pressure. 4. Atrial natriuretic peptide did not significantly alter stop-flow sodium concentrations. 5. These findings indicate that ANP does not directly alter sodium transport across medullary collecting ducts. 6. It is proposed that ANP acts via a mediator to alter sodium movement across terminal segments of the nephron.

The effect of perindopril on blood pressure in humans on different sodium intakes

Perindopril is a new inhibitor of converting enzyme activity with a prolonged half-life. Thirty-two patients with essential hypertension and a diastolic blood pressure greater than 95 mm Hg were stratified into two groups according to their 24 h urine sodium excretion. They were randomized in a double-blind fashion to placebo or perindopril and a dose titration made in steps of 2, 4, 6, and 8 mg given once daily at weekly intervals. The goal diastolic blood pressure was 90 mm Hg. Goal blood pressure was achieved in 11 of 16 patients on perindopril and 3 of 6 patients on placebo. Perindopril caused a fall in BP of 22/11 (supine) and 27/14 (erect) mm Hg while the placebo group had falls of 3/2 (supine) and 3/0 (erect) mm Hg. Most of the blood pressure fall occurred in the first week of therapy with 2 mg/day. Side effects were few and occurred mainly in the placebo phase. There was no alteration in urine protein, white cell count, plasma urea, or creatinine. The fall in blood pressure achieved at the end of the titration or with 2 mg did not differ between the two groups. There was no correlation between blood pressure response and 24 h urine sodium or plasma renin activity. These results indicate that perindopril is an effective antihypertensive drug that appears to work equally well in patients on high or low sodium intake.

Comparative studies of reduced sodium and high potassium diet in hypertension

A decrease in sodium intake or an increase in potassium intake reduces blood pressure (BP) in people with essential hypertension. Additional potassium prevents, in sodium-sensitive people and rats, the rise in BP caused by extra sodium chloride. In people with a diastolic BP between 90 and 100 mm Hg, dietary reduction of sodium to 80 mmol/day and dietary increase of potassium to 90 mmol/day caused a fall in BP of 5.1/4.2 and 3.6/3.1 mm Hg, respectively, greater than was observed in the control group. There was a negative interaction between the two diets when used together with a BP change of 4.0/3.6 mm Hg. The fall in BP with sodium restriction was not reversed by the addition of sodium chloride and a similar fall in BP was not achieved with potassium chloride. It is possible that the response is due to some other factor. A strong correlation existed between the change in urine Na:K and the fall in BP. This study indicates that a reduced sodium or an increased potassium diet will reduce BP and should be considered for the initial management of essential hypertension.

The role of the macula densa in renin release: studies by microperfusion

The role of the macula densa in control of renin release and in mediation of tubulo-glomerular feedback was investigated following orthograde microperfusion in Munich Wistar rats. Tubules of surface glomeruli were perfused, drip-fixed with glutaraldehyde and biopsy cores taken containing perfused and non-perfused glomeruli. Serial sections were examined by light and electron microscopy. In some animals dilated basolateral spaces were observed between cells in control maculae densa but no spaces were found following microperfusion with hypertonic NaCl, isotonic mannitol or hypotonic NaCl containing 1 mg/l frusemide. In other animals no spaces were found in control cores, and perfusion with the above solutions had no effect. However, in such animals, tubules perfused with hypotonic NaCl (71 mmol/kg H2O) had prominent basolateral spaces in their maculae densa. The presence of dilated basolateral intercellular spaces is generally associated with osmotically driven water flow. The extent of dilatation of such spaces in the macula densa is correlated with transepithelial osmotic or ionic gradients and may indicate activity of these cells in the recognition of distal tubular fluid composition.

Results of a randomized trial of end-to-side portacaval shunt and distal splenorenal shunt in alcoholic liver disease and variceal bleeding

Since 1976, we have compared the end-to-side portacaval shunt (PCS) with the distal splenorenal shunt (DSRS) in patients with alcoholic liver disease and recurrent variceal bleeding. Fifty-four patients were randomly assigned to receive either shunt procedure. There were 27 patients in each group and both groups were highly comparable in clinical and laboratory characteristics. Median follow-up was 31 mo in each group. Postoperative complications and operative mortality (7% after PCS, 12% after DSRS) were comparable. Spontaneous portasystemic encephalopathy developed in 32% of the patients at risk after PCS and in 39% after DSRS. Rebleeding from varices occurred in 4% of the patients after PCS and in 27% after DSRS. Cumulative survival was not significantly different between groups (5-yr survival: 31% after PCS, 43% after DSRS). We have failed to demonstrate superiority of DSRS in our patients with alcoholic liver disease with respect to postoperative encephalopathy or survival, and have experienced an unusually high rate of variceal rebleeding after DSRS.

Trauma center and the OR. A cooperative approach to caring for the massively injured

Communication must be established between the operating room and trauma center. At SNJRTC, perioperative nurses rotate through the trauma center and are part of nursing grand rounds on trauma patients. This system has improved interdepartmental relations, educational development, and most importantly, established a system in which patients have the best chance of survival as a result of the cooperative approach to the care of the massively injured.

The role of sodium restriction in the management of hypertension

More than 50 studies have investigated the effect of altered sodium intake on blood pressure. A regression line drawn through the change in blood pressure and change in sodium intake indicates that blood pressure alters about 10 mmHg (1 mmHg = 133.322 Pa) for every 100 mmol/day alteration in sodium intake, a change similar to that observed in between-population "studies." The studies that have failed to show a change in blood pressure have usually been in people with a blood pressure less than 130/90 mmHg. Normotensive people appear to tolerate a higher intake of sodium before blood pressure rises, but if increased sufficiently, blood pressure rises in most people. Sodium restriction reduces blood pressure in people with severe hypertension, moderate hypertension and mild hypertension. It may be the cause of blood pressure increase associated with age and the reason for the higher prevalence of hypertension and vascular disease in Western communities. Sodium restriction should be used to treat people with elevated blood pressure.

Factors that determine the response of people with mild hypertension to a reduced sodium intake

One hundred and eighty-six males who had had 3 run-in visits entered the study with a supine diastolic BP 95-110 mm Hg. This was followed by 3 pretreatment and 3 post-treatment visits. One hundred and sixty patients were given advice to reduce sodium intake after visit 3, and twenty-six patients served as control. In the control group there were relatively insignificant changes between the pre and post visits. In the diet group blood pressure fell by 13/9 mm Hg; urine sodium from 168 to 85 mmol/day and plasma renin activity rose from .50 to .77 ng AI/ml/h. Regression analysis showed that the only cross-sectional correlations were PRA with age, urine sodium and plasma potassium. There were highly significant correlations between the change in urinary sodium and the change in blood pressure and between the changes in blood pressure and plasma renin activity. Multiple Regression Analysis indicated that the final diastolic blood pressure achieved depended upon the initial diastolic blood pressure, the fall in sodium intake, and was reduced by the rise in plasma renin activity. Patients who responded to sodium restriction had a lower initial renin value than other patients. This study emphasises the importance of the interaction between sodium, potassium and renin in the determination of blood pressure levels.

Discovery of Sodium in the Atmosphere of Mercury

The spectrum of Mercury at the Fraunhofer sodium D lines shows strong emission features that are attributed to resonant scattering of sunlight from sodium vapor in the atmosphere of the planet. The total column abundance of sodium was estimated to be 8.1 x 10(11) atoms per square centimeter, which corresponds to a surface density at the subsolar point of about 1.5 x 10(5) atoms per cubic centimeter. The most abundant atmospheric species found by the Mariner 10 mission to Mercury was helium, with a surface density of 4.5 x 10(3) atoms per cubic centimeter. It now appears that sodium vapor is a major constituent of Mercury's atmosphere.

The role of potassium in control of blood pressure

Extra potassium intake has been found to be a determinant of blood pressure for epidemiological and experimental reasons. People with hypertension have a small fall in blood pressure with added potassium. Potassium chloride (48 mmol/day) was given to 36 male patients with high blood pressure; 5 did not comply with therapy. In the entire group of patients, potassium chloride had no significant effect on blood pressure, but prevented the rise in blood pressure and pulse rate produced by posture. In patients with a urinary Na+ excretion less than 75 mmol per 10 mmol creatinine, potassium chloride had no effect on supine blood pressure, but prevented the rise in blood pressure and pulse rate with standing. In those on a high sodium intake, potassium chloride lowered both the systolic and diastolic pressures. In sodium-responsive subjects, potassium chloride prevented the rise in blood pressure induced by sodium chloride but had no significant effect on blood pressure when on a low sodium intake. These results indicate that potassium reduces the rise in blood pressure caused by sodium chloride and reduces the increased sympathetic postural response seen in people on a low sodium intake.

The role of sodium and potassium in the control of blood pressure

When sodium intake was increased from 70-200 mmol/day in normotensive volunteers, their blood pressure rose by 6/4 mmHg. In most people over 50 years, blood pressure rose and it also rose in about 15% of younger people. Those who had a rise in blood pressure had a creatinine clearance lower than others when on a reduced sodium intake. In the sodium sensitive group creatinine clearance rose when sodium intake was increased. In the people with a rise in blood pressure there was a fall in plasma volume. Increased sodium intake altered a number of factors that control sodium transport across cell membranes. The changes are complex but suggest that genetically inherited and environmentally caused defects are necessary to allow hypertension to be expressed. Reduction of sodium intake reduced blood pressure in people with mild hypertension. Potassium interacted with sodium to reduce the rise in blood pressure caused by sodium. Sodium intake and blood pressure are linked by many mechanisms. If the intake is excessive for that individual or if there are defective control mechanisms, hypertension will result.

Renal colic

The most common and overt manifestation of a ureteric calculus is renal colic. This paper discusses its clinical presentation and diagnostic difficulties and follows the management of the patient until the stone is passed or retrieved surgically; it does not address the overall picture of renal calculous disease. The role of subsequent metabolic investigation is outlined.

Diuretics 1984

Diuretics increase water excretion by inhibiting sodium transport in the nephron. They can be grouped according to their chemical class or (more practically) their site of action in the nephron. The site determines certain features of their effect, an important one being their effect on potassium excretion. Diuretics which act late in the nephron inhibit sodium transport in the region in which potassium is secreted, causing retention of potassium and hydrogen ions. These diuretics produce a hyperkalaemic acidosis; most others cause loss of potassium and hydrogen and a hypokalaemic alkalosis.

Adverse reactions to long-term diuretic therapy for hypertension

Diuretics are important drugs used in therapy for hypertension. Diuretics have a number of side effects, some of which have long-term consequences. In this study diuretics were used to treat individuals with mild hypertension. Patients receiving diuretics as sole therapy had an increased mortality due to an excess number of deaths from myocardial infarction or sudden death. In patients given alpha-methyldopa or propranolol as well as a diuretic drug, this effect was not observed. The increased mortality may be due to an increased susceptibility to arrhythmias in individuals receiving diuretics, and this was prevented by drugs that interfere with the effects of the sympathetic nervous system.

The effect of ketanserin in essential hypertension

Ketanserin, a 5HT2-receptor blocking drug was given to 17 patients with essential hypertension. Satisfactory control was achieved in 13 patients. Control was not as satisfactory when given once daily. There was no rebound effect when the drug was ceased. Side-effects were few. Ketanserin was a satisfactory drug to reduce blood pressure in patients with moderate hypertension.

Effect of calcitonin on urine concentration in the rat

Because mammalian distal nephron segments with both calcitonin- and antidiuretic hormone- (ADH) sensitive adenylate cyclase activity have been described, in vivo and in vitro experiments were performed to study the effect of calcitonin on rat distal nephron water permeability. Calcitonin 1 and 0.1 U/ml, but not 0.01 U/ml, significantly increased the diffusional water permeability in the isolated papillary collecting duct by 15 and 11%, respectively. However, this effect was small when compared with a 68% increase with a supramaximal concentration of ADH (from 4.0 +/- 0.3 to 6.7 +/- 0.9 microns/s; n = 6, P less than 0.01). The normal increase in water permeability with increasing concentration of ADH (0.02 and 0.2 mU/ml) was depressed by the previous addition of calcitonin (1 U/ml) to the bath but was unaltered with the supramaximal ADH concentration (2 mU/ml). Verapamil, a compound that antagonizes cellular calcium entry, did not alter the effect of calcitonin on diffusional water permeability. Calcitonin in concentrations of 0.05, 0.5, and 5 U/ml produced a significant reduction in urine flow and free water clearance. Pretreatment with calcitonin in these concentrations inhibited the antidiuretic action of ADH. These studies suggest that calcitonin acts as a partial agonist to ADH within the distal nephron. It is unclear whether such an action represents a physiological or a pharmacological effect.

The mechanism of polyuria in rats pretreated with lithium studies by in vitro microperfusion

The collecting ducts in papillae taken from normal rats have a measurable increase in diffusional tritiated water (THO) permeability with ADH 5 mu unit/ml and this increase is maximal with antidiuretic hormone (ADH) 100 mu unit/ml added to media. The presence of plasma from rats pretreated with lithium to make them polyuric inhibited the response to ADH. The lowest concentration of ADH that caused a measurable increase in diffusional water permeability was 50 mu unit/ml and the increase was maximal with ADH 2000 mu unit/ml. The maximum response to ADH did not differ whether plasma from control or lithium pretreated rats was used. However, the dose-response curve to ADH was shifted to the right by the plasma from lithium-pretreated rats. Lithium added to the plasma from control rats did not alter the response to ADH. It is proposed that lithium given to rats causes a circulatory factor to be produced that inhibits in a competitive fashion the response of the collecting duct to ADH. Such an effect would explain many features of the impairment of water excretion associated with lithium use.