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Kerkez SA, Poston L, Wolfe CD, Quartero HW, Carabelli P, Petruckevitch A, Hilton PJ. A longitudinal study of maternal digoxin-like immunoreactive substances in normotensive pregnancy and pregnancy-induced hypertension. Int J Gynaecol Obstet 1991. [DOI: 10.1016/0020-7292(91)90553-h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Barton IK, Streather CP, Hilton PJ, Bradley RD. Successful treatment of severe lactic acidosis by haemofiltration using a bicarbonate-based replacement fluid. Nephrol Dial Transplant 1991; 6:368-70. [PMID: 1870755 DOI: 10.1093/ndt/6.5.368] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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Goldsmith DJ, Poston L, Watson M, Morris J, Hilton PJ, Cragoe EJ. Effect of autologous serum on human leucocyte Na+/H+ exchange and intracellular pH. Clin Sci (Lond) 1990; 79:357-64. [PMID: 2171856 DOI: 10.1042/cs0790357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
1. Leucocyte Na+/H+ exchange and intracellular pH were investigated in physiological buffer containing bicarbonate. 2. The amiloride analogue 5-(N,N-hexamethylene) amiloride (1 x 10(-5) mol/l), an inhibitor of Na+/H+ exchange, had no significant effect on resting leucocyte pH, Na+ influx or Na+ content. 3. Ammonium chloride washout induced a profound intracellular acidosis, stimulating Na+/H+ exchange. This led to a 236% increase in Na+ influx. Eighty-eight per cent of this increase was inhibited by 5-(N,N-hexamethylene) amiloride. This demonstrates that 5-(N,N-hexamethylene) amiloride is an effective inhibitor of Na+/H+ exchange in human leucocytes. 4. The recovery from intracellular acidosis was shown to be dependent entirely on the presence of extracellular Na+. The Ki for inhibition by 5-(N,N-hexamethylene) amiloride of the recovery was 0.5 mumol/l. 5. Incubation with serum increased Na+ influx and Na+ content: the maximal effect was reached at 20% dilution. Serum (10%, v/v) increased influx by 40%, and 20% (v/v) serum by 102%, over resting levels. Only 43% of the serum-induced increase in Na+ influx was inhibited by 5-(N,N-hexamethylene) amiloride. This represented one-fifth of total Na+ influx. 6. Leucocyte intracellular pH increased on incubation with serum. This alkalinization was inhibited using 5-(N,N-hexamethylene) amiloride. 7. Studies of Na+/H+ exchange in leucocytes in physiological and pathological states are more likely to reflect the state in vivo if carried out in the presence of autologous serum.
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Woolfson RG, Hilton PJ, Poston L. Effects of ouabain and low sodium on contractility of human resistance arteries. Hypertension 1990; 15:583-90. [PMID: 2161405 DOI: 10.1161/01.hyp.15.6.583] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Earlier work with rat arteries has resulted in a widely held assumption that resistance artery smooth muscle will not contract on exposure to a reduced transplasmalemmal sodium gradient. In view of the well-recognized low sensitivity of rat tissue to cardiac glycosides, we have investigated the effects of altering the transplasmalemmal sodium gradient on vascular smooth muscle tone by using human resistance arteries. Incubation of arteries in low sodium or in ouabain to inhibit active sodium efflux for 1 hour increased the contractile response to caffeine stimulation; this finding indicated enhanced calcium buffering by the sarcoplasmic reticulum. Prolonged incubation in ouabain in the presence of phentolamine or diltiazem resulted in a concentration-dependent increase in the tone of resting human resistance arteries. Reduction of the transplasmalemmal sodium gradient by incubation in low sodium buffer effected an increase in tone similar to that obtained in the presence of ouabain. These results suggest that alteration of the transplasmalemmal sodium gradient may increase the vascular smooth muscle tone of human resistance arteries by altering intracellular calcium handling. This is a new finding in human resistance arteries and may involve inhibition and, indeed, reversal of sodium-dependent calcium efflux. A concentration-dependent potentiation of tone was found after the addition of ouabain to submaximally activated arteries. Sodium-calcium exchange may also play a pivotal role in this mechanism.
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Kerkez SA, Poston L, Wolfe CD, Quartero HW, Carabelli P, Petruckevitch A, Hilton PJ. A longitudinal study of maternal digoxin-like immunoreactive substances in normotensive pregnancy and pregnancy-induced hypertension. Am J Obstet Gynecol 1990; 162:783-7. [PMID: 2316589 DOI: 10.1016/0002-9378(90)91010-a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The serum of women in the third trimester of pregnancy demonstrates cross-reactivity with some commercially available antibodies to digoxin. A number of studies have suggested that levels of this digoxin-like immunoreactive substance(s) are further increased in patients with pregnancy-induced hypertension, and some have proposed that the digoxin-like immunoreactive substance could be useful as a predictor of pregnancy-induced hypertension. We measured digoxin-like immunoreactive substance levels every 2 weeks throughout the third trimester in 170 women; of these, 20 developed hypertension. Digoxin-like immunoreactive substance levels rose with gestational age. A graph of the slope of digoxin-like immunoreactive substance plotted against gestational age was fitted for the results obtained from each woman. There was no significant difference in the mean rate of increase of digoxin-like immunoreactive substance level per week between pregnancy-induced hypertension and normotensive pregnancy, nor was there any difference between these two groups at any gestational age studied. These results suggest that measuring digoxin-like immunoreactive substance levels is not useful as a predictor of pregnancy-induced hypertension.
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31
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Richards NT, Poston L, Hilton PJ. Cyclosporin A inhibits endothelium-dependent, prostanoid-induced relaxation in human subcutaneous resistance vessels. J Hypertens 1990; 8:159-63. [PMID: 2162879 DOI: 10.1097/00004872-199002000-00010] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of cyclosporin on endothelium-dependent relaxation of human subcutaneous resistance vessels was investigated. Resistance vessels were obtained from normal subjects undergoing routine surgery. Acetylcholine-induced relaxation was shown to consist of at least two components, one mediated through vasodilatory prostanoids, the other through endothelium-derived relaxing factor (EDRF). Incubation with cyclosporin inhibited endothelium-dependent relaxation, as assessed by the response to acetylcholine. The inhibitory effect of cyclosporin on the acetylcholine response was most marked in the presence of methylene blue, which is an inhibitor of EDRF. This suggests that the inhibition of endothelium-dependent relaxation by cyclosporin is mediated by an effect on vasodilatory prostanoids.
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Richards NT, Poston L, Goldsmith DJ, Cragoe EJ, Hilton PJ. Endothelin-induced contraction of human peripheral resistance vessels is partly dependent on stimulation of sodium-hydrogen exchange. J Hypertens 1989; 7:777-80. [PMID: 2555411 DOI: 10.1097/00004872-198910000-00002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The role of Na-H exchange in endothelin-induced contraction of human peripheral resistance vessels was investigated. Endothelin produced a dose-dependent contraction which was greatly attenuated in the presence of a low extracellular sodium concentration. Inhibition of Na-H exchange by the amiloride analogue 5-(N,N-hexamethylene) amiloride (5-NNHA) resulted in a greater than 65% relaxation of a maximal endothelin-induced contraction in the presence of normal extracellular sodium. However, in the presence of a low extracellular sodium concentration, inhibition of Na-H exchange only resulted in a 25% relaxation. These data suggest that endothelin-induced vasoconstriction of human peripheral resistance vessels is mediated in part by stimulation of Na-H exchange.
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33
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Poston L, Morris JF, Wolfe CD, Hilton PJ. Serum digoxin-like substances in pregnancy-induced hypertension. Clin Sci (Lond) 1989; 77:189-94. [PMID: 2548800 DOI: 10.1042/cs0770189] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. Endogenous digoxin-like immunoreactivity (EDLI) was measured in the serum of 85 normotensive pregnant (NTP) women and 77 women with pregnancy-induced hypertension (PIH) by a radioimmunoassay (New England Nuclear). All women were in the third trimester. 2. EDLI, which was undetectable in serum from non-pregnant women, was present in NTP and PIH and was significantly higher in PIH. EDLI correlated with gestational age in NTP, but not in PIH. 3. Ouabain-sensitive Na+ transport was estimated in normal peripheral blood leucocytes after incubation with sera from 50 NTP and 42 PIH women. Significant inhibition of active Na+ transport occurred only with the serum of hypertensive patients without proteinuria. 4. EDLI did not correlate with the effect of the sera on active Na+ transport. The radioimmunoassay therefore provides a poor index of Na+ transport inhibitory activity in PIH.
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34
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Richards NT, Poston L, Hilton PJ. Cyclosporine A inhibits relaxation but does not induce vasoconstriction in human subcutaneous resistance vessels. J Hypertens 1989; 7:1-3. [PMID: 2708808 DOI: 10.1097/00004872-198901000-00001] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of cyclosporine on the functional characteristics of human subcutaneous resistance vessels were investigated. Resistance vessels were obtained from normal subjects undergoing routine surgery. Incubation with cyclosporine did not alter the resting tone of the vessels, but decreased the maximum contractile response and the sensitivity of the vessels to stimulation with exogenous noradrenaline and potassium. Cyclosporine decreased the rate of spontaneous relaxation and inhibited endothelium-dependent relaxation as assessed by the response to acetylcholine. Paradoxically, endothelium-independent relaxation as assessed by the response to sodium nitroprusside was augmented. Hypertension induced by cyclosporine may, in part, be explained by a reduction in relaxation of peripheral resistance vessels.
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35
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Morris JF, Poston L, Wolfe CD, Hilton PJ. A comparison of endogenous digoxin-like immunoreactivity and sodium transport inhibitory activity in umbilical arterial and venous serum. Clin Sci (Lond) 1988; 75:577-9. [PMID: 2850130 DOI: 10.1042/cs0750577] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. Endogenous digoxin-like immunoreactivity (EDLI) was measured by radioimmunoassay for digoxin in 13 paired samples of arterial and venous umbilical cord serum. EDLI was present in vein and artery, but was higher in the venous samples (P less than 0.025). 2. The venous cord serum inhibited the ouabain-sensitive sodium efflux rate constant of a normal mixed leucocyte population when compared with the effect of arterial cord serum (P less than 0.005). 3. It is suggested that the placenta may be involved in the production or metabolism of neonatal EDLI and of the inhibitor of sodium transport.
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36
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Poston L, Morris J, Hilton PJ. Free fatty acids and leucocyte sodium transport. Clin Sci (Lond) 1987; 73:445-6. [PMID: 3665363 DOI: 10.1042/cs0730445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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37
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Morris JF, McEachern MD, Poston L, Smith SE, Mulvany MJ, Hilton PJ. Evidence for an inhibitor of leucocyte sodium transport in the serum of neonates. Clin Sci (Lond) 1987; 73:291-7. [PMID: 3652634 DOI: 10.1042/cs0730291] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
1. In confirmation of previous studies, serum obtained from cord blood demonstrated endogenous digoxin-like immunoreactivity (EDLI). Sera from pregnant women in the third trimester also demonstrated EDLI, which disappeared after delivery. 2. Cord serum inhibited the total sodium efflux rate constant of a mixed leucocyte preparation when compared with the effect of control serum. This inhibition resulted from a depression of the ouabain-sensitive (sodium pump) component of the rate constant. 3. An ultrafiltrate of the serum (mol. wt. less than 30,000) also inhibited ouabain-sensitive leucocyte sodium transport when compared with filtrate obtained from control serum. 4. DHA-S Dehydroepiandrosterone sulphate (DHA-S) and cortisone, both present in high concentration in cord serum, demonstrated EDLI but did not affect leucocyte sodium transport in the cells of normal subjects. 5. DHA-S had no effect on sodium transport or vasoconstrictor activity in human omental resistance vessels. 6. It is concluded that EDLI of cord serum is associated with sodium transport inhibitory activity. This is unlikely to be attributable to DHA-S or cortisone.
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Abstract
A case is described where a patient received less oxygen than was set on the Rotameters. The cause was traced to a selective leak of oxygen via an open cyclopropane needle valve. Several recommendations are put forward to prevent a recurrence.
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39
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Poston L, Hilton PJ. Reversible inhibition of leucocyte sodium pumps by circulating serum factor in essential hypertension. BMJ : BRITISH MEDICAL JOURNAL 1986; 293:1029. [PMID: 2429722 PMCID: PMC1341822 DOI: 10.1136/bmj.293.6553.1029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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40
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Barton IK, Mansell MA, Hilton PJ. A simple method for the measurement of red-cell calcium concentration. Ann Clin Biochem 1986; 23 ( Pt 5):610-1. [PMID: 3767300 DOI: 10.1177/000456328602300521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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41
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Hilton PJ. Genetic and environmental factors influencing cellular sodium transport in essential hypertension. JOURNAL OF CLINICAL HYPERTENSION 1986; 2:109-13. [PMID: 2428945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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42
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Gray HH, Hilton PJ, Richardson PJ. Effect of serum from patients with essential hypertension on sodium transport in normal leucocytes. Clin Sci (Lond) 1986; 70:583-6. [PMID: 3709064 DOI: 10.1042/cs0700583] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This study has confirmed that serum from patients with essential hypertension inhibits sodium transport and elevates intracellular sodium in normal human leucocytes in vitro when compared with that of well matched normotensive controls. The magnitude of this effect was positively correlated with the diastolic blood pressure of the hypertensive patient. The degree of sodium transport inhibition conferred by the hypertensive's serum was correlated with the abnormal sodium transport in the hypertensive's own leucocytes. These results confirm the presence of a serum inhibitor of sodium transport in essential hypertension. The relationship between the inhibitory effect and severity of hypertension argues that it may be of mechanistic importance.
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Hilton PJ. A resuscitation box for every anaesthetist? Anaesthesia 1985; 40:486-7. [PMID: 4014627 DOI: 10.1111/j.1365-2044.1985.tb10854.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The results are reported of a questionnaire which asks whether or not anaesthetists routinely carry any resuscitation equipment in their cars. A small, simple resuscitation box is described which is adequate for the majority of life-threatening situations.
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45
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Gray HH, Poston L, Johnson VE, Hilton PJ. Effect of the calcium antagonist verapamil on human leucocyte sodium transport in vitro. Clin Sci (Lond) 1985; 68:239-41. [PMID: 3967468 DOI: 10.1042/cs0680239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Sodium efflux rate constants and intracellular sodium were measured in leucocytes from healthy volunteers in the presence and absence of the calcium antagonist verapamil hydrochloride. Verapamil stimulated sodium pump activity and this effect was dependent on the presence of external calcium. Verapamil has been reported to reverse the abnormality of sodium transport seen in leucocytes from patients with essential hypertension and the present study demonstrates that sodium pump activity in leucocytes from control subjects is also stimulated by exposure to verapamil in vitro. This direct cellular effect appears to be due to the calcium antagonist properties of the drug.
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Mason JC, Poston L, Hilton PJ. Sodium pump activity in thymocytes of rats with Goldblatt hypertension. Clin Sci (Lond) 1985; 68:11-4. [PMID: 3964725 DOI: 10.1042/cs0680011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Sodium transport has been studied in thymocytes of one-kidney, one-clip (1K, 1C) and two-kidney, one-clip (2K, 1C) models of hypertension in the rat. No differences of intracellular sodium or sodium transport could be demonstrated in either model when compared with sham-operated controls. The experiments provide no evidence to support the concept that an inhibitor of sodium transport is associated with the development of hypertension in the one-kidney, one-clip rat. A previously unrecognized effect of incubation time and cell density on thymocyte sodium metabolism is reported.
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Johnson VE, Hilton PJ. Frusemide-sensitive sodium and potassium transport by human leucocytes. Clin Sci (Lond) 1985; 68:89-91. [PMID: 3964733 DOI: 10.1042/cs0680089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Frusemide-sensitive sodium and potassium transport by normal human leucocytes has been studied in vitro by both isotopic and net flux techniques. In physiological media the leucocyte exhibits a frusemide-sensitive influx of sodium and potassium of equal magnitude compatible with a 1:1 co-transport system. Cells exposed to zero external sodium and potassium (osmolality maintained with choline) demonstrated a frusemide-sensitive sodium and potassium efflux. Frusemide-sensitive potassium influx was dependent on the presence of external sodium but frusemide-sensitive sodium influx persisted unchanged in the absence of external potassium. Frusemide-sensitive potassium influx was dependent on external chloride but frusemide-sensitive sodium influx was chloride-independent. These last two observations make it likely that the frusemide-sensitive pathway is capable of operating in modes other than sodium-potassium co-transport.
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Gray HH, Johnson VE, Poston L, Hilton PJ. Sodium transport by leucocytes and erythrocytes in hypertensive subjects and their normotensive relatives. JOURNAL OF HYPERTENSION. SUPPLEMENT : OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF HYPERTENSION 1984; 2:S467-9. [PMID: 6599701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Intracellular sodium content and ouabain-sensitive sodium efflux rate constant were measured in leucocytes and erythrocytes from subjects with untreated essential hypertension and also in normotensive subjects with and without a family history of hypertension. Leucocytes from hypertensives were again shown to have a higher intracellular sodium content and lower ouabain-sensitive sodium efflux rate constant than normotensive controls but there were no differences between those normotensive subjects with and those without a family history of hypertension. No differences in erythrocyte sodium content or efflux rate constant were seen between any of the three groups.
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Nunan TO, King M, Bull P, Banatvala JE, Jones NF, Hilton PJ. Parenteral acyclovir therapy for cytomegalovirus infection after renal transplantation. Clin Nephrol 1984; 22:28-31. [PMID: 6090044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Three patients who had received cadaveric renal transplants developed fevers within three months of transplantation. Concurrent cytomegalovirus infection was confirmed by virological studies. In all three patients there was both a clinical and virological response to a five day course of intravenous acyclovir. In one patient the dose required to produce this response was 5 mg/kg/day; however two patients required 10 mg/kg/day. All three patients remain well after 8-12 months follow-up.
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Gray HH, Poston L, Hilton PJ, Smith SJ, Markandu ND, MacGregor GA. Reversal by verapamil of defect in sodium transport in leucocytes in essential hypertension. BMJ 1984; 288:673-5. [PMID: 6421427 PMCID: PMC1444437 DOI: 10.1136/bmj.288.6418.673] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The effect of treatment with verapamil on cell sodium transport was studied in the leucocytes of patients with essential hypertension. Previously described abnormalities of sodium efflux rate constant and intracellular sodium content were confirmed, the component of the sodium efflux rate constant sensitive to ouabain being lower and the intracellular sodium content higher in the patients compared with controls. Verapamil reversed these abnormalities and reduced blood pressure.
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