Characterization of endothelium-dependent relaxations resistant to nitro-L-arginine in the porcine coronary artery.

1. Previous studies, demonstrated that endothelium-dependent relaxations which are resistant to nitro-L-arginine (an inhibitor of nitric oxide synthase) are accompanied by membrane hyperpolarization in the porcine coronary artery. The present experiments were designed to characterize further this type of endothelium-dependent relaxation in response to bradykinin by measuring isometric force in isolated rings of that artery. The experiments were performed in the presence of indomethacin to rule out vasoactive prostanoids. 2. Bradykinin induced comparable endothelium-dependent relaxations of proximal and distal rings of porcine coronary arteries contracted with prostaglandin F2 alpha in the presence of nitro-L-arginine. 3. Bradykinin and SIN 1 (a donor of nitric oxide) reduced contractions induced by prostaglandin F2 alpha in an additive fashion in the presence of nitro-L-arginine. 4. Bradykinin (in the presence of nitro-L-arginine) relaxed the tissues contracted with tetraethylammonium, prostaglandin F2 alpha, phorbol 12, 13-diacetate or endothelin, with similar pD2 values. 5. The time course of the relaxations induced by bradykinin (in the presence of nitro-L-arginine) and UK14304 (an alpha 2-adrenoceptor agonist, in the absence of the inhibitor of nitric oxide synthase) were comparable. 6. These results suggest that, in the porcine coronary artery, nitro-L-arginine-resistant relaxations (a) are distributed similarly in the proximal and distal parts of the artery, (b) contribute to inhibition of vascular smooth muscle with nitric oxide in an additive fashion, (c) occur during contractions induced by various contractile agents and (d) do not precede those mediated by nitric oxide.


Effect of a 5-lipoxygenase inhibitor and leukotriene antagonist (PF 5901) on PAF-induced airway responses in neonatally immunized rabbits.

1. Aerosol administration of platelet activating factor (PAF) (80 micrograms ml-1 for 60 min) to neonatally immunized rabbits caused bronchoconstriction which was far in excess of that produced by a comparable aerosol of bovine serum albumin (BSA), the carrier molecule for PAF. Bronchoconstriction of a similar magnitude was elicited by PAF in immunized, sham-immunized and normal rabbits. 2. Aerosol administration of PAF to immunized rabbits induced enhanced airway responsiveness to inhaled histamine in all animals tested, 24 h and 72 h after exposure. In not all cases had airways responsiveness returned to basal levels at 1 week following PAF challenge. In contrast, following exposure of immunized rabbits to BSA, no significant changes in airway responsiveness to histamine were evident at any of the measured time points. 3. A significant increase in the total number of inflammatory cells recovered in bronchoalveolar lavage (BAL) fluid was determined 24 h and 72 h following PAF exposure in immunized rabbits. This was associated with a significant increase in the number of neutrophils and eosinophils. Similar changes were observed following exposure of PAF to normal and sham-immunized rabbits. No change in the total number of inflammatory cells was obtained in BAL after BSA challenge to immunized rabbits; however, neutrophil numbers were significantly increased. 4. PF 5901, a specific inhibitor of the 5-lipoxygenase pathway of arachidonic acid metabolism and a leukotriene D4 antagonist, at a dose of 10 mg (direct intratracheal administration) significantly inhibited the airway resistance (RL) component of the bronchoconstriction induced by PAF in neonatally-immunized rabbits. Doses of 10 mg, 3 mg and 1 mg PF 5901 (direct intratracheal administration) were sufficient to inhibit significantly the PAF-induced increase in airways responsiveness to inhaled histamine in immunized rabbits. PF 5901 however, failed to alter the pulmonary cell infiltration induced by PAF,as assessed by BAL.5. We suggest from the results of the present study that PAF induces consistent and long-lasting increases in airways responsiveness to histamine in immunized rabbits, which is mediated, at least in part, by products of the 5-lipoxygenase metabolic pathway. Furthermore, the inability of PF 5901 to inhibit the influx of inflammatory cells into the airway lumen following PAF challenge may suggest that bronchial hyperresponsiveness and cellular infiltration are not strictly associated events.


Attenuation of vasoconstriction by endogenous nitric oxide in rat caudal artery.

1. The effects of NG-nitro-L-arginine (L-NNA), NG-nitro-L-arginine methyl ester (L-NAME), haemoglobin and methylene blue have been examined on vascular reactivity in the rat isolated caudal artery. The effects of L-NNA and sodium nitroprusside were also investigated on the stimulation-induced (S-I) efflux of noradrenaline in the rat caudal artery. 2. L-NNA (10 microM) and L-NAME (10 microM) significantly attenuated the vasodilator responses to acetylcholine (1 nM-1 microM), but had no effect on vasodilator responses to papaverine (1-100 microM). 3. Vasoconstrictor responses to sympathetic nerve stimulation (3 Hz, 10 s), noradrenaline (0.01-1 microM), methoxamine (1-10 microM), 5-hydroxytryptamine (0.01-0.3 microM), phenylephrine (0.1-10 microM), endothelin-1 (10 nM) and KCl (40 mM) were significantly enhanced by 10 microM L-NNA. L-NAME (10 microM) caused a significant enhancement of vasoconstrictor responses to noradrenaline and sympathetic nerve stimulation in endothelium-intact, but not in endothelium-denuded tissues. 4. Haemoglobin and methylene blue (both 10 microM) enhanced the vasoconstrictor responses to sympathetic nerve stimulation and noradrenaline. The enhancements were absent in endothelium-denuded arterial segments. 5. In endothelium-denuded arterial segments precontracted with phenylephrine, the vasodilator responses to the nitric oxide donor, sodium nitroprusside (0.1-300 nM) were decreased by increasing the level of precontraction. 6. L-NNA (10 microM) had no effect on the S-I efflux of radioactivity from arteries in which transmitter stores had been labelled with [3H]-noradrenaline. 7. These results suggest that endothelial nitric oxide attenuates vasoconstrictor responses in the rat caudal artery through activation of soluble guanylate cyclase to decrease smooth muscle contractility. Therefore, the findings provide evidence that nitric oxide acts as a functional antagonist to oppose vasoconstriction.


Effects of cicletanine on haemodynamics, arrhythmias and extent of necrosis during coronary ligation in rabbits.

1. The effects of cicletanine on arrhythmias, haemodynamics and extent of necrosis during myocardial ischaemia were investigated in rabbits subjected to coronary ligation. 2. Cicletanine increased cardiac output prior to coronary occlusion (P < 0.01) but had no other significant haemodynamic effects at this time and did not significantly alter heart rate, blood pressure or cardiac output during 30 min of ischaemia or 30 min of reperfusion. 3. Ventricular fibrillation and mortality were greater in control (65% and 60% respectively) than treated animals (15.4% and 15.4%, P < 0.01). 4. The extent of myocardial necrosis expressed as a percentage of the area at risk was also reduced by cicletanine from 61 +/- 8% in controls to 37 +/- 6% (P < 0.05). 5. These findings indicate that cicletanine attenuates arrhythmias and preserves myocardium in the early phase of ischaemia and this effect appears to be independent of an established antihypertensive action.


Role of protein kinase C in the regulation of histamine and bradykinin stimulated inositol polyphosphate turnover in adrenal chromaffin cells.

1. The possibility that bradykinin- or histamine-stimulated inositol polyphosphate accumulation may be regulated by protein kinase C (PKC) in bovine adrenal chromaffin cells has been addressed. 2. Initial experiments confirmed that the phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA) dramatically inhibited agonist-stimulated [3H]-inositol phosphate accumulations in [3H]-inositol prelabelled cells. In contrast, the PKC inhibitor, Ro 31-8220, did not affect this response. 3. Histamine (100 microM) or bradykinin (100 nM) evoked rapid increases in inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) mass accumulations (maximal accumulations within 10 s and 30 s, respectively) which declined towards basal values over a 10 min incubation period. TPA (1 microM) significantly attenuated the peak Ins(1,4,5)P3 response to bradykinin and histamine by 30% and 70% respectively. In contrast, TPA did not significantly affect agonist-stimulated Ins(1,3,4,5)P4 responses. 4. Ro 31-8220 (10 microM) significantly enhanced the maximal Ins(1,4,5)P3 accumulations elicited by both bradykinin and histamine. 5. The results indicate that the initial Ins(1,4,5)P3 response to either bradykinin or histamine in bovine adrenal chromaffin cells can be attenuated by PKC activation by phorbol ester and enhanced by PKC inhibition by Ro 31-8220. In contrast, agonist-stimulated Ins(1,3,4,5)P4 accumulation does not appear to be affected by these manipulations of PKC activity. Possible bases for differential modulation of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 are discussed.


ATP activates P2x-contracting and P2y-relaxing purinoceptors in the smooth muscle of mouse vas deferens.

1. The mechanism for the low potency of exogenous ATP in producing contraction at the P2x-purinoceptors in the smooth muscle of the mouse vas deferens (VD) was examined. 2. The measure of the breakdown of ATP in contact with the VD showed that its degradation was limited and did not account for its weak contractile effect. 3. Externally applied, ATP induced a small and transient contraction but a marked and prolonged increase of the cytosolic Ca2+ concentration ([Ca2+]i), which suggests an efficient binding to the P2x-purinoceptors. Such a calcium-force dissociation was not observed with beta, gamma-methylene ATP (beta, gamma-Me-ATP), a structural ATP analogue. 4. The force response of precontracted VD to ATP was biphasic, consisting of a small initial contraction followed by a sustained marked relaxation. In contrast, beta, gamma-Me-ATP elicited a pronounced contraction without ensuing relaxation. 5. ATP was more potent than adenosine in producing relaxation, and the relaxation was not antagonized by 8-phenyltheophylline, suggesting the activation of P2-purinoceptors. 6. For this relaxation, the rank order of potency was 2-methyl-thio-ATP (2-MeSATP) > ATP > beta, gamma-Me-ATP, which is characteristic for the P2y-purinoceptors. 7. Reactive Blue 2, a P2y-purinoceptor antagonist, was found to reduce the relaxation mediated by ATP. 8. These results indicate that ATP acts in VD not only on contracting but also on relaxing P2-purinoceptors, eliciting thereby overlapping opposite effects. In VD, the classical low potency of ATP or contraction is thus not explained by its low bioavailability or its low binding, but rather by its low specificity for the contracting P2x-purinoceptors, leading to the activation of the relaxing P2y-purinoceptors.


Pharmacological profile of GR117289 in vitro: a novel, potent and specific non-peptide angiotensin AT1 receptor antagonist.

1. This paper describes the effects of GR117289 (1-[[3-bromo-2-[2-(1H-tetrazol-5-yl)phenyl]-5-benzo-furanyl]methyl ]-2-butyl-4-chloro-1H-imidazole-5-carboxylic acid) at angiotensin receptors and binding sites in rabbit aorta, rat liver and bovine cerebellum preparations in vitro. 2. In rabbit isolated aortic strips, GR117289 (0.3, 1 and 3 nM) caused a concentration-related, insurmountable suppression of the concentration-response curve to angiotensin II (AII). When the contact time was increased, a greater degree of antagonism of AII was observed, suggesting that GR117289 is slow to reach equilibrium. A pKB of 9.8 +/- 0.1 was calculated for GR117289 after 3 h incubation. GR117289 (1 microM) did not affect contractile responses to phenylephrine or 5-hydroxytryptamine (5-HT) in the rabbit aorta. 3. GR117289 (1 nM) alone caused a marked suppression and a slight rightward displacement of the AII concentration-response curve. Co-incubation with the competitive, surmountable AT1 receptor antagonist, losartan (10 nM, 100 nM and 1 microM), resulted in a concentration-related upward and rightward displacement of the concentration-response curve to subsequently administered AII. In separate experiments in which preparations were pre-incubated with GR117289 (1 nM), subsequent addition of losartan (1 microM) for 2, 15 or 45 min caused a further, but similar, rightward displacement of the concentration-response curve to subsequently administered AII with a time-dependent increase in the maximum response.4. Suppression of All-induced contractile responses, caused by superfusion with GRI17289 (0.3, 1 or 3 nM) was not reversed by continuously washing the tissues for 3 h; in fact, the potency of GRI 17289 was slightly enhanced after this period.5. In rat liver membranes, GRI17289 was a potent competitor with [3H]-AII for AT, binding sites(pKi = 8.7 +/- 0.1) but in bovine cerebellum membranes, it was a very weak competitor for AT2 binding sites (pKi<6). Pre-incubation of rat liver membranes with GRI17289 had little effect on its affinity(pKi = 9.1 +/- 0.21), but increasing the concentration of bovine serum albumen in the assay buffer from 0.001% to 0.1% w/v decreased affinity (pKi= 7.5 +/- 0.1).6. In saturation binding experiments in rat liver membranes, GRI 17289 (12 nM) increased the Kd of[3H]-AII from 0.28 +/- 0.06 nM to 0.37 +/- 0.02 nM, and decreased Bm. from 10.0 +/- 0.1 to 5.6 +/-0.3 fmol mg' tissue. In other experiments, GR1 17289 (1 jIM) did not alter the rate of dissociation of[3H]-AII from AT1 binding sites, following addition of excess unlabelled All.7. In rabbit aorta vascular smooth muscle membranes, GR1 17289 competed with ['25I]-Sar'1le8 All for binding to AT, binding sites. In the presence of 0.1% w/v bovine serum albumen, a pIC50 of 7.6 +/- 0.1 was calculated. Under the same conditions, but with rat liver membranes, a pIC50 of 7.8 +/- 0.1 was determined.8. Taken together, these results show that GRI17289 is a potent, specific, selective and insurmountable antagonist at angiotensin AT, receptors. Its profile in the rabbit aorta is consistent with the proposalthat GRI17289 is a slowly reversible (pseudo-irreversible) antagonist at these receptors.


Involvement of nitric oxide in the regional haemodynamic effects of perindoprilat and captopril in hypovolaemic Brattleboro rats.

1. Male, homozygous Brattleboro (i.e. vasopressin-deficient) rats were chronically instrumented with pulsed Doppler flow probes and intravascular catheters, and were studied 5 h after a subcutaneous injection of an hyperoncotic solution of polyethylene glycol to render them hypovolaemic, and hence dependent on the renin-angiotensin system for maintenance of haemodynamic status. Pilot experiments showed that, in this model, primed infusion of perindoprilat (0.05 mg kg-1 bolus, 0.05 mg kg-1 h-1 infusion) or captopril (0.2 mg kg-1 bolus, 0.2 mg kg-1 h-1 infusion) just abolished the pressor effect of angiotensin I (120 pmol), and had similar initial hypotensive and renal hyperaemic vasodilator effects. 2. Perindoprilat had more sustained hypotensive, and mesenteric and hindquarters vasodilator effects than captopril in the presence of saline. In the presence of NG-nitro-L-arginine methyl ester (L-NAME 3 mg kg-1 h-1), the renal vasodilator effects of perindoprilat were unchanged, whereas the other haemodynamic effects of perindoprilat and captopril were reduced. Hence, in the presence of L-NAME, all haemodynamic effects of perindoprilat were greater than those of captopril. 3. The renal hyperaemic vasodilator effects of acetylcholine were abolished by L-NAME and by perindoprilat, and were markedly reduced by captopril. However, since perindoprilat and captopril caused such marked renal hyperaemic vasodilatation themselves, it is feasible this change in baseline status contributed to their effects. It is unlikely this could be a full explanation of the results, because the haemodynamic effects of lemakalim were unchanged under any experimental conditions. 4. Bradykinin alone, or in the presence of saline, caused mesenteric hyperaemic vasodilatation whereas, in the presence of perindoprilat or captopril, bradykinin caused marked renal and mesenteric vasoconstrictions. However, in the additional presence of L-NAME, the mesenteric vasoconstriction was reduced, yet the hypotensive effect of bradykinin was augmented. One possible explanation of these observations is that, in the presence of L-NAME and either perindoprilat or captopril, bradykinin caused marked coronary vasoconstriction, leading to a reduction in cardiac output. 5. Neither perindoprilat nor captopril impaired the pressor, or renal, mesenteric, or hindquarters vasoconstrictor effects of L-NAME. Indeed, in their presence, the effects of L-NAME were generally enhanced, consistent with perindoprilat and captopril causing activation of nitric oxide-dependent mechanisms that were subsequently inhibited by L-NAME.


Characteristics of the contractile response of rabbit aorta produced by cromakalim in calcium-free solution.

1 The effect of potassium channel opening compounds has been investigated in the smooth muscle of rabbit aorta under Ca-free conditions. Examination of the characteristics of the response has been performed using cromakalim as the prototype compound. 2 In order of potency, Ro 31-6930, cromakalim, minoxidil sulphate and pinacidil each produced a contraction in rabbit aortic strips bathed in Ca-free MOPS-buffered physiological salt solution (PSS). In contrast, forskolin, glyceryl trinitrate and nifedipine each failed to increase tension under identical conditions. Cromakalim also evoked contraction of bovine trachealis muscle bathed in Ca-free PSS. 3. The contractile response to cromakalim in rabbit aortic strips was of delayed onset (15-20 min) and reached a plateau after approximately 120 min (1.8 g maximum with 1 microM cromakalim). No cromakalim-induced tension changes were observed in either 1 mM or 2.5 mM Ca-containing PSS. 4. Raising the [KCl] of the Ca-free PSS to 65.9 mM fully inhibited the cromakalim-induced contraction in rabbit aortic strips. In addition, pretreatment of aortic strips with the sulphonylurea glibenclamide antagonized the subsequent mechanical response to cromakalim. 5. In Ca-free PSS, cromakalim (1 microM) stimulated 42K-efflux with a time-course corresponding to the contractile event. Glibenclamide (1 microM) inhibited this cromakalim-induced 42K-efflux. 6. In sharp microelectrode studies in bovine trachealis, cromakalim (10 microM) produced a sustained membrane hyperpolarization in normal PSS. In contrast, the cromakalim-induced hyperpolarization in Ca-free PSS was not sustained. The fading of the hyperpolarization was temporally correlated with the increase in tension under these experimental conditions. 7. It is concluded that the K-channel opener-induced smooth muscle contractile response revealed in Ca-free PSS is the consequence of K-channel opening. The nature of the detailed mechanism which underlies this contractile phenomenon remains to be determined.


Discrimination between ETA- and ETB-receptor-mediated effects of endothelin-1 and [Ala1,3,11,15]endothelin-1 by BQ-123 in the anaesthetized rat.

1. The influence of BQ-123 (a selective ETA-receptor antagonist) on the haemodynamic response elicited by endothelin-1 (ET-1) and [Ala1,3,11,15]ET-1 (a selective ETB-receptor agonist) was studied in anaesthetized rats instrumented with ultrasonic Doppler flow probes on the carotid, coeliac, mesenteric, renal and iliac arteries. 2. BQ-123 alone (1.6 mumol kg-1, i.v.) induced a decrease in femoral mean arterial pressure (AP), accompanied by a systemic vasodilatation. The response was maximal after 3 min and then returned slowly to baseline. None of these effects was observed after a 0.016 mumol kg-1 dose of BQ-123. 3. ET-1 (1 nmol kg-1, i.v.) induced a biphasic response characterized by a transient initial decrease in AP accompanied by regional vasodilatation (mainly in the carotid and iliac beds) and by immediate mesenteric and renal vasoconstrictions. This was followed, within 1 min, by a marked and prolonged increase in AP accompanied by systemic vasoconstriction. Pretreatment with BQ-123 (1.6 mumol kg-1, i.v., 8 min before ET-1) increased and prolonged the vasodilator effect of ET-1 (mainly in the carotid, coeliac, mesenteric and iliac beds) and reduced its systemic vasoconstrictor effects with marked regional differences (the coeliac, mesenteric and renal beds being poorly affected). 4. [Ala1,3,11,15]ET-1 (3 nmol kg-1, i.v.) induced an initial and marked decrease in AP accompanied by regional vasodilatation (mainly in the carotid, coeliac and iliac beds) and by mesenteric and renal vasoconstrictions. This was followed, within 5 min, by a small increase in AP and systemic vasoconstriction. All these effects were dose-dependent. Pretreatment with BQ-123 (1.6 tmol kg'; 8 min before ET-1) did not modify the early effect of [Ala'3""5]ET-l, but abolished its secondary vasoconstrictor effect except in the mesenteric bed.5. This study demonstrates that pretreatment with BQ-123 not only reduced a large part of the sustained vasoconstrictor activity of ET-1, suggesting the involvement of ETA-receptors, but also enhanced the early vasodilator activity of ET-1 revealing a functional antagonism between the two effects. The vasodilator effect of [Ala1"3""l '5]ET-1 was not affected by BQ-123 and ET-1 induced a similar vasodilatation, that was potentiated by BQ-123, suggesting the involvement of ETB-receptors in this vasodilator response. Marked regional differences were however observed which might be partly related to different levels of functional antagonism between ETB- and ETA-mediated effects, but differences in receptor types, or subtypes, cannot be excluded, mainly in the mesenteric and renals beds.


Dissociation between biochemical and functional effects of the aldose reductase inhibitor, ponalrestat, on peripheral nerve in diabetic rats.

1. The aim of the study was to examine the effects in rats of two different doses of the aldose reductase inhibitor, ponalrestat, on functional measures of nerve conduction and sciatic nerve biochemistry. 2. After 1 month, streptozotocin-induced diabetes produced 22%, 23% and 15% deficits in conduction velocity of sciatic nerves supplying gastrocnemius and tibialis anterior muscles and saphenous sensory nerve respectively compared to controls. These deficits were maintained over 2 months diabetes. 3. Slower-conducting motor fibres supplying the interosseus muscles of the foot did not show a diabetic deficit compared to onset controls, however, there was a 13% reduction in conduction velocity after 2 months diabetes relative to age-matched controls, indicating a maturation deficit. 4. Resistance to hypoxic conduction failure was investigated for sciatic nerve trunks in vitro. There was an increase in the duration of hypoxia necessary for an 80% reduction in compound action potential amplitude with diabetes. This was progressive; after 1 month, hypoxia time was increased by 22% and after 2 months by 57%. 5. The effect of 1-month treatment with the aldose reductase inhibitor, ponalrestat, on the abnormalities caused by an initial month of untreated diabetes was examined. Two doses of ponalrestat were employed, 8 mg kg-1 day-1 (which is equivalent to, or greater than, the blockade employed in clinical trials), and 100 mg kg-1 day-1. 6. Sciatic nerve sorbitol content was increased 7 fold by diabetes. Both doses were effective in reducing this; 70% for 8 mg kg-1 day-1, and to within the control range for 100 mg kg-1 day-1.


Potassium channel modulation in rat portal vein by ATP depletion: a comparison with the effects of levcromakalim (BRL 38227).

1. The effects of levcromakalim and of adenosine 5'-triphosphate (ATP) depletion on membrane potential and ionic currents were studied in freshly-dispersed smooth muscle cells of rat portal vein by use of combined voltage- and current-clamp techniques. 2. Levcromakalim (1 microM) induced a glibenclamide-sensitive, non-inactivating K-current (IKCO) and simultaneously inhibited the slow, transient outward, delayed rectifier K-current (ITO). Levcromakalim also hyperpolarized the portal vein cells by approximately 20 mV. 3. Reduction of intracellular ATP by removal of glucose and carboxylic acids from the recording pipette and of glucose from the bath fluid, induced a slowly-developing, non-inactivating and glibenclamide-sensitive K-current (Imet) within 60-300 s after breaking the membrane patch. Imet reached peak amplitude after 300-900 s, remained at a plateau for 200-800 s and then slowly ran down. At the peak of Imet, the cells were hyperpolarized by approximately 20 mV and their input conductance was increased by 42%. 4. At the time of maximum development of Imet, the delayed rectifier current, ITO, was reduced by 48%. 5. In the absence of glucose and carboxylic acids, addition of 1 microM free ATP to the recording pipette almost doubled the magnitude of Imet. At a holding potential of -10 mV, Imet was increased from 124 +/- 11 pA to 228 +/- 54 pA whereas the time-course of development and run-down of Imet was unaffected. 6. During the development and after the run-down of Imet, levcromakalim (1-10 microM) failed to induce IKCO. 7. Stationary fluctuation analysis of the current noise associated with Imet revealed a unitary conductance of between 10-20 pS in a physiological potassium gradient. A second contaminating current with an underlying unitary conductance of approximately 150 pS remained after Imet had run down. 8. It is concluded that IKCO induced by levcromakalim and Imet are carried by the same population of relatively small conductance, glibenclamide-sensitive K-channels. The open state of these is increased by procedures designed to lower intracellular ATP concentrations. 9. The simultaneous inhibition of the delayed rectifier current (ITO) by both levcromakalim and during the development of Imet is highly significant. It suggests that levcromakalim could modify the interaction of ATP with sites linked to more than one type of K-channel. This results in the opening of those channels which underlie IKCO (and which are normally inhibited by ATP binding) together with the modulation of phosphorylation-dependent channels such as those which underlie ITO.


Endothelium-dependent increase in vascular sensitivity to phenylephrine in long-term streptozotocin diabetic rat aorta.

1. The effect of short- and long-term streptozotocin (STZ)-induced diabetes (12 and 52 weeks) on the vascular response to phenylephrine was examined in the isolated thoracic aorta with and without intact endothelium from diabetic, age matched control rats and diabetic rats treated with insulin. 2. Twelve weeks after induction of diabetes, aortae with intact endothelium demonstrated no changes either in sensitivity (defined as pD2) or contractility (defined as the maximal developed tension per aortic tissue wet weight) to phenylephrine. 3. In contrast, 52 weeks after induction of diabetes, aortae with intact endothelium demonstrated an increased sensitivity to phenylephrine while contractility to phenylephrine was not changed. Insulin treatment partially corrected the increased sensitivity to phenylephrine observed in diabetic rat aorta. 4. Removal of endothelium abolished the difference in phenylephrine sensitivity between diabetic and control aortae at 52 weeks. 5. Pretreatment of intact aortae with methylene blue, an inhibitor of endothelium-derived relaxing factor (EDRF), abolished the difference in phenylephrine sensitivity between control and diabetic rat aortae at 52 weeks, while pretreatment with indomethacin, an inhibitor of cyclo-oxygenase, had no effect. These results suggest that decreases in production or release of EDRF might be responsible for the increased vascular sensitivity to phenylephrine observed in long-term STZ diabetic rats. 6. Acetylcholine-induced relaxation, which is EDRF-dependent, was less in diabetic rat aortae with intact endothelium at 52 weeks, but not at 12 weeks. These results further support the theory that decreases in capacity of the endothelium to synthesize or release EDRF may occur in long-term STZ diabetic rats.


Phosphoramidon blocks big-endothelin-1 but not endothelin-1 enhancement of vascular permeability in the rat.

1. Changes in vascular permeability following intravenous injections of human big-endothelin-1 (big-ET-1) and endothelin-1 (ET-1) were measured by extravasation of Evans blue dye (EB, 20 mg kg-1) in selected tissues. 2. A low dose of big-ET-1 (40 pmol kg-1) failed to alter vascular permeability but a dose of 400 pmol kg-1 increased EB extravasation in the trachea, upper and lower bronchi, and lung parenchyma by 55 to 69% (P < 0.05). Vascular permeability was also enhanced in the liver, spleen, kidney, heart, and diaphragm by 20, 14, 41, 25, and 67%, respectively (P < 0.05). 3. Upon injection of ET-1 (400 pmol kg-1), EB extravasation increased in the upper and lower bronchi, lung parenchyma, liver, pancreas, kidney, heart, and diaphragm. 4. Administration of ET-1 and big-ET-1 was not associated with significant systemic responses. 5. Pretreatment with phosphoramidon (PA) blocked the response to big-ET-1 in all tissues examined but this inhibitor failed to alter the response to ET-1. 6. We conclude from these results that the dose-dependent increase in vascular permeability induced by big-ET-1 in various tissues follows its conversion to ET-1 by the endothelin converting enzyme, a PA-sensitive process.


Prediction of response to lithotripsy--the use of scanning electron microscopy and X-ray energy dispersive spectroscopy.

A single urine sample was obtained from each of 38 patients before and immediately after treatment with a Wolf Piezolith 2300. Each sample was analysed for crystals using scanning electron microscopy and X-ray energy dispersive spectroscopy. In all cases it was possible to make a stone diagnosis prior to treatment and there was 100% correlation between the pre- and post-treatment diagnosis. All stones smaller than 90 mm2 on plain X-ray cleared with piezoelectric lithotripsy alone, regardless of composition. Larger stones composed of calcium oxalate were all successfully fragmented, but 5 of 15 mixed or phosphate stones failed to respond.


Treatment of stones in caliceal diverticula: extracorporeal shock wave lithotripsy versus percutaneous nephrolitholapaxy.

Stones in caliceal diverticula may cause symptoms for which treatment is indicated. Both extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrolitholapaxy (PNL) are recommended. We have evaluated the results of ESWL treatment of stone-containing caliceal diverticula and compared these with the results obtained by percutaneous surgery. In the ESWL group, 15 patients were treated with an electromagnetic lithotriptor (Siemens Lithostar). After 3 months, plain abdominal X-rays revealed that only 2 patients were both stone-free and symptom-free. Of the 13 patients with residual fragments, 7 had no symptoms. The remaining 6 were treated by a lower pole resection (n = 3), a percutaneous procedure (n = 2) and long-term administration of antibiotics (n = 1). Sixteen patients were treated percutaneously. Puncture failed in 3 and they underwent a lumbotomy. In the remaining 13 patients the stones were reached by direct puncture (n = 12) or via an adjacent calix (n = 1). After 3 months, 10 patients were stone-free and had no symptoms. Morbidity consisted of post-operative bleeding (n = 3) and high fever (n = 1). It was concluded that caution should be exercised in the treatment of stone-containing caliceal diverticula. Only in symptomatic cases is treatment indicated and ESWL is the first choice. If ESWL fails (residual stones and persistent symptoms), PNL should be performed, although it is associated with a higher morbidity rate.


Clinical study of patients with renal carcinoma surviving for more than 10 years after nephrectomy.

Of 207 patients with renal carcinoma we studied 50 who survived for more than 10 years after nephrectomy. These 50 patients were younger than the others at the time of operation and included more females. They had lower stage and lower grade tumours. Recurrence was detected in 18/50 patients and 6 died from cancer. Recurrence developed approximately 10 years after nephrectomy. Eleven patients with recurrences had metastases to a single organ and 9 received multidisciplinary treatment, mainly surgery and radiotherapy. The survival rate 10 years after nephrectomy was lower in patients with recurrences than in those without recurrent tumours and there was a significant decrease in the survival rate 17 years after nephrectomy. Although the patients had low grade and low stage tumours 10 years after nephrectomy, careful follow-up is recommended in such cases as it is possible that they may have dormant tumours.


Does too much urology damage your eyesight? Study of macular function.

A study comparing the macular function of both eyes of 130 urological surgeons was carried out to investigate whether the increased light exposure to the endoscoping eye caused any deterioration of macular function. The non-endoscoping eye was used as a control. A sophisticated computer test of colour contrast sensitivity was used. The computer assesses the degree of brightness at which the subject is just able to detect a coloured grating, and for each eye this is expressed as a threshold for the red/green axis and the blue/yellow (tritan) axis. The subjects also completed a questionnaire about their working patterns and their general and ophthalmic history and had a brief examination of the fundus. The results do not suggest that urologists are suffering any significant macular damage as a result of their work with endoscopes.


Blue light emission from urological equipment. Can it damage the eyes?

Blue light present in the visible spectrum at the lower wavelengths can cause damage to the retinas of monkeys and rats. In the present study the light sources and instrumentation available to the urologist were evaluated to see whether they posed a hazard. The light emitting directly from the sources, cables and telescopes was tested and these levels were found to be dangerous to the eye when compared with the safety limit recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). When the light at the eyepiece of the telescopes which had been reflected off a surface was measured, the blue light levels did not appear to be harmful when compared with the ACGIH safety limit. The use of filters is discussed and the transmission of 2 types of filters shown. While the level of blue light emission from the eyepiece remains within the ACGIH level, there are no data on long-term exposure. The addition of a blue light filter may be beneficial until such time as videoendoscopy becomes the norm. The light from light sources should be protected by a shutter and more care taken with the emission from cables and telescopes.


Abdominal aortic aneurysms presenting as renal colic.

In a 6-year period, 9 patients were referred by their General Practitioners to the urology unit with a clinical diagnosis of renal colic but were subsequently found to have leaking abdominal aortic aneurysms (AAA). In all cases of loin pain, especially in the elderly patient, the possibility of a leaking abdominal aneurysm must be considered. If no intrinsic urological cause for the pain is found or patterns suggestive of ureteric obstruction are seen on urography, ultrasound examination of the aorta-iliac vessels should be performed. Magnetic resonance imaging (MRI) and computed tomography (CT) scans may be useful adjuncts to this investigation.


Psychological aspects of female urinary incontinence in general practice.

The aim of this study was to determine whether urge incontinence was associated with a higher prevalence of psychological symptoms than other types of incontinence. The psychological aspects of 110 women presenting with urinary incontinence in general practice were assessed by means of standardised questionnaires and medical history-taking. The results showed no difference in psychological characteristics between patients with urge incontinence and those with other types of incontinence. These findings were contrary to the conclusions of almost all other studies based on populations selected for specialist care. It was concluded that in general practice the psychological approach to urinary incontinence depends more on the individual needs of the patient than specifically on the type of incontinence.


Epidural anaesthesia in the management of the painful bladder.

Bladder pain is a difficult symptom to manage. Epidural anaesthesia, which was used in 10 patients with sensory disorders, carries a low morbidity and helps to define those patients with severe bladder pain who might benefit from denervation procedures.


Does residual urine predispose to urinary tract infection?

The relationship between the presence of post-micturition residual urine and urinary tract infection is unclear. We have performed a retrospective analysis of 342 studies on bladder emptying and compared the incidence of bacterial infection and pyuria in patients with residual urinary volumes of more or less than 100 ml. In patients with a residual volume > 100 ml 49/219 studies showed evidence of pyuria and 28/198 studies of patients whose residual urine was less than 100 ml showed evidence of infection. In cases where the residuals were > 100 ml 33/123 had evidence of pyuria and 19/109 infection. There was no significant increase in the rate of infection in patients with large residual urinary volumes, suggesting that there is no definite correlation between post-micturition residues and urinary tract infection.


Samuel Pepys and his bladder stone.

Samuel Pepys, as a young man, developed a bladder stone and, by the age of 25 years, realised that only surgery could deliver him from his agony. The chances of success in an age that was ignorant of sepsis were slender, but he opted for surgery. The operation, carried out through the perineum without anaesthetic by a master barber surgeon, was successful and Pepys survived. Although left sterile, he was far from impotent and he went on to achieve fame and fortune as Secretary to the Navy and President of the Royal Society. His greatest fame came after his death with the publication of his diary, which was to become one of the best known and best loved books in the language.


Rome pouch: pre-peritoneal continent ileal reservoir with hydraulic valve.

We present our experience with a modified technique for constructing a continent ileal reservoir, using the terminal ileum in a pre-peritoneal position. The ureters were implanted using the Le Duc-Camey technique; the Benchekroun valve was used as a continence mechanism. This technique was used in 18 patients and its advantages and complications are discussed.


The quality of life after radical radiotherapy for bladder cancer.

The quality of life in 72 patients who had shown a complete response to radiotherapy, using a modified bladder symptom score and the Nottingham health profile, was compared with the quality of life in a similar control group matched for age and sex. There was no significant difference in either group. The records of 69 patients who had undergone post-radiation salvage cystectomy were reviewed, looking specifically at surgical complications. There were 3 post-operative deaths (5%), 3 pulmonary emboli and 3 fistulae--with some overlap of complications. Five patients who underwent cystectomy for intractable symptoms in the apparent absence of recurrent tumour were found to have residual cancer in the excised specimens.


Urologists' attitudes to the management of bladder cancer.

All consultant urologists in Great Britain and Ireland were sent 2 questionnaires relating to their management policies in bladder cancer; 82% and 78% respectively of questionnaires were completed and returned. The answers demonstrated a wide variation among urologists about the management of common clinical problems.


Irrigation or no irrigation after transurethral prostatectomy?

Urologists remain divided as to the need for routine irrigation following transurethral prostatectomy (TURP). This randomised prospective study compared a policy of irrigation with that of no irrigation in a consecutive group of 200 patients undergoing TURP. In the irrigation group, a mean of 15 litres of irrigating fluid was used in each patient and one-third of patients required at least one bladder washout. In the no irrigation group, although two-thirds of the patients required at least one bladder washout, only one-third required more than one washout. No significant difference in blood loss, electrolyte balance, infection rate or recovery was seen in the 2 groups. This study led to a local change in practice, converting from a policy of routine irrigation to one of no irrigation.


Local hyperthermia for prostatic disease: in vitro studies on human prostatic cancer cell lines.

Local hyperthermia for benign and malignant prostatic disease remains largely empirical. In an attempt to understand the biological action of hyperthermia, and its potentiation by antiandrogen seen in clinical practice, the interaction of the two has been studied in prostatic cancer cell lines. Human prostatic cancer cell lines LNCaP and DU 145 were studied to examine the effects of heat shock treatment (HST), androgen (5 alpha-dihydrotestosterone: 5 alpha DHT) and antiandrogen (hydroxyflutamide: OH-Flut) on cell growth and survival. Response (measured as increased DNA content) to 5 alpha DHT demonstrated that LNCaP was androgen sensitive, whereas DU 145 was androgen insensitive; OH-Flut stimulated LNCaP growth but had no effect on DU 145 growth. Thermotolerance was exhibited by DU 145 cells but not by LNCaP cells. The combination of HST followed by OH-Flut markedly reduced survival of LNCaP cells compared with HST alone. This effect was not observed in DU 145 cells. The enhanced cytotoxic effect of antiandrogen and hyperthermia could minimise the effect of thermotolerance in malignant cells surviving initial hyperthermia treatment and might suggest real clinical value for the combination or sequence.


Mitomycin C and aminoglutethimide in the treatment of metastatic prostatic cancer: a phase II study.

In a phase II study, 24 patients with metastatic prostatic cancer were treated with mitomycin C 15 mg/m2 i.v. every 6 weeks, combined with aminoglutethimide 250 mg twice a day. A low dose of 37.5 mg cortisone acetate was supplied daily to compensate for adrenal cortical suppression. A partial response was demonstrated in 4 of 24 evaluable patients with bi-dimensionally measurable metastases. Stable disease occurred in 8 patients over a period of more than 6 months. Within the maximum cumulative dose limit of 2 mg/kg body weight mitomycin C, toxicity was observed in 21 cases, including 2 deaths due to treatment toxicity. The poor response rate and high toxicity suggest that the addition of aminoglutethimide does not enhance the effect of mitomycin C in these patients.


High resolution ultrasonography in the diagnosis of simple intratesticular cysts.

Simple intratesticular cysts are a rare condition. High resolution sonography permits unequivocal sonographic differentiation between intratesticular cysts and neoplastic lesions with a cystic appearance, so that conservative treatment seems justified. Seventeen patients with sonographically diagnosed intraparenchymal testicular cysts were followed up for an average of 29 months. No increase in size or change in echo pattern was found and surgical therefore not indicated.


Total nephrectomy in children: a clinicopathological review.

The records of 85 children undergoing total nephrectomy have been reviewed. Diagnoses ranged between pyelonephritis (37 patients), renal tumours (25), renal dysplasia and multicystic kidney (16), obstructive uropathy (6) and renal vein thrombosis (1). In the pyelonephritic group a contributory ipsilateral abnormality was demonstrated in 36 of the 37 children. Vesicoureteric reflux (VUR) was the most common abnormality in this cohort and was usually of a severe grade. Calculus disease was present in 9 patients, only 1 of whom had VUR. Of the remaining 7 patients with pyelonephritis, 6 had evidence of obstruction to the upper tracts. Calculus disease poses a more severe threat to the childhood kidney than the well known risk factors of vesicoureteric reflux and obstructive uropathy.


The role of tissue expanders in vaginoplasty for congenital malformations of the vagina.

There are many techniques of vaginoplasty in congenital malformations of the vagina, all of which involve the use of labial and perineal skin flaps. The results are not uniformly satisfactory because of delayed stenosis in many patients. To avoid this complication, we have used labial expansion with tissue expanders to obtain an elastic and sufficiently large skin flap. We recommend this technique in patients with the adrenogenital syndrome associated with varying degrees of virilisation and in other intersex anomalies.


Continent urinary reservoir in exstrophy/epispadias complex.

The outcome of 15 children and young adults who underwent reconstruction of continent urinary reservoirs (CUR) from January 1987 to 1990 is presented. Ten patients were male and 5 female with an age range of 3 to 20 years. There were 13 patients with bladder exstrophy and 2 with incontinent epispadias. In 8 cases the urinary diversion was performed for an inadequate bladder capacity following successful closure (3), failed attempted closure (3), female epispadias (1) and following successful urethroplasty in 1 case of male epispadias. A tiny fibrotic bladder plate unsuitable for attempted closure was the indication for diversion in 3 patients. Faecal and urinary incontinence following ureterosigmoidostomy (2 patients) and trigonosigmoidostomy (2) was the reason to consider re-diversion in 4 previously diverted patients. In 10 patients an Indiana pouch was performed. The Mitrofanoff procedure was used in 5 cases with caecum (2), sigmoid colon (2) or transverse colon (1) as the urinary reservoir. All patients are continent on clean intermittent catheterisation with stable renal function. Three patients developed large stones within the reservoir and needed open cystolithotomy. This series supports the efficacy of CUR as an alternative procedure to traditional forms of urinary diversion in the management of selected patients with exstrophy/epispadias complex.


Challenges in the management of prostate cancer.

An estimated 32,000 American men will die of prostate cancer this year. Local prostate cancer may be successfully treated by radical prostatectomy or radiotherapy. Advanced cases may necessitate the use of hormonal ablation with bilateral orchiectomy, an approach that is regarded as the gold standard of therapy but not always the preferred treatment of patients. Oestrogen therapy is an alternative but is associated with side effects, such as hot flushes and gynaecomastia, which frequently lead to treatment cessation. Luteinising hormone-releasing hormone (LHRH) analogues work by initially producing a surge of androgen, followed by a down-regulation in hormone production to effect a medical castration. Various groups have studied the effects of androgen blockade administered as monotherapy and as combination therapy (LHRH analogue plus antiandrogen). The National Cancer Institute intergroup protocol 0036, which is the largest cooperative study to date of patients with advanced prostatic cancer, showed that combination therapy with leuprolide and flutamide offered greater benefit in both time to disease progression and median survival while circumventing tumour flare and its associated symptoms. Thus, combination therapy for total androgen ablation may become the new treatment standard for advanced prostatic cancer, pending further studies in the efficacy and cost-effectiveness of all available treatments.


Postsurgical management of the patient undergoing radical prostatectomy.

Radical prostatectomy is a useful procedure for the treatment of prostate cancer limited to the gland; however, failure may occur as a result of the immediate or delayed complications of surgery, or to disease recurrence related to incomplete tumour excision. Seventy-nine radical prostatectomies were performed between April 1985 and August 1991 in patients with prostate cancer (primarily stage B1) who averaged 63 years of age. Immediate post-operative complications included vesicocutaneous fistulae, cystic lymphangiomas, abdominal wall abscesses, extraperitoneal haematoma, acute cholecystitis, and enterocutaneous fistula. Massive pulmonary embolism accounted for 2 deaths. Of the 77 surviving patients followed up for an average of 34 months, 79.2% (61) were continent, 15.6% had stress-related incontinence or severe incontinence and 5.2% were lost to follow-up. Sexual potency was preserved in 13 of the 33 patients (39%) who were pre-operatively potent. A favourable outcome as defined by no recurrence was seen in 69 patients (87.3%). Four patients (5.1%) are living with recurring prostatic cancer and 1 patient has died of the disease 46 months after surgery.


Management of stage C adenocarcinoma of the prostate.

A review of numerous clinical series dealing with the treatment of patients with clinical stage C prostate cancer failed to find the treatment or a combination of treatments that is superior to any other. Accurate staging, which was difficult in older studies, and stage migration, which complicates the comparison of recent to older studies, may contribute to this lack of identification. The majority of patients ultimately experience disease progression and are therefore treated with hormonal therapy, the use of which obscures survival data for initial modes of treatment. These observations point to the need for control of randomised clinical trials to identify effective treatments in the future.


Nasogastric intubation and elective abdominal surgery.

The use of nasogastric tubes after elective abdominal surgery remains standard practice for many surgeons. Such tubes, however, cause much discomfort and are associated with significant morbidity. This paper reviews the arguments for and against nasogastric intubation, and finds little evidence to support its continued routine use.


Function of the human colon.

Despite the volume of research on human colonic dysfunction, little is known about colonic function in health. This has stemmed partly from the difficulty in obtaining access to the organ. Two approaches have been used: studies on patients with stomas, and intestinal intubation techniques. The colonoscope has also recently been used to gain access. All these methods have limitations and results must be interpreted with caution. The accepted roles of the colon include the conservation of water and electrolytes and the controlled evacuation of faeces. Recent research has demonstrated its importance as a metabolic organ with an influence on overall metabolism, an effect that may in large part be attributed to the activity of colonic microflora. Evidence demonstrating that the defunctioned colon behaves differently from the functioning colon in the same individual has implications for a proper understanding of the organ, as practically all previous in vivo studies have been conducted in cleansed or defunctioned human colon.


Mycetoma.

Mycetoma is a chronic infective condition of tropical and subtropical regions. It is commoner in males, especially those in their third or fourth decade who work on the land. The clinical triad of subcutaneous nodule, sinuses and discharge usually leads to diagnosis; the disease is commonly painless. Treatment is by extensive surgical excision of affected areas and may include limb amputation. Recurrence is common, rates ranging from 20 to 90 per cent. Medical treatment may be used on its own or as an adjunct to surgery. Although such therapy may cure over half of those with actinomycetoma (caused by bacteria, mainly aerobic actinomycetes), those affected by eumycetoma (caused by fungi) have a poorer prognosis and may require many years of drug therapy.


Aetiology and treatment of chylous ascites.

A series of 45 patients with chylous ascites has been reviewed. The age at presentation ranged from 1 to 80 (median 12) years; 23 patients were aged < or = 15 years. Thirty-five patients had an abnormality of the lymphatics (primary chylous ascites); in the remaining ten, the ascites was secondary to other conditions, principally non-Hodgkin's lymphoma (six patients). Two principal mechanisms of ascites formation were identified using lymphangiography and inspection at laparotomy: leakage from retroperitoneal megalymphatics, usually through a visible lymphoperitoneal fistula (14 patients); and leakage from dilated subserosal lymphatics of the small intestine, invariably associated with leaking lacteals causing protein-losing enteropathy (24 patients). Both sites of leakage were present in a further five patients. In the remaining two patients, chyle was leaking from normal mesenteric lymphatics, in one via a ruptured mesenteric lymph cyst and in the other from the site of a previous lymph node biopsy. Other associated lymphatic abnormalities were present in 36 patients, lymphoedema of the leg being the commonest (26 patients). All patients were initially treated conservatively with dietary manipulation; this was the most satisfactory treatment for those with leaking small bowel lymphatics. Surgery (fistula closure, bowel resection or insertion of a peritoneovenous shunt) was performed in 30 patients. Closure of a retroperitoneal fistula, when present, was the most successful operation, curing seven of the 12 patients so treated.


Prostacyclin production from seeded prosthetic vascular grafts.

Endothelial cell seeding has been proposed as a method of improving patency rates in small-calibre prosthetic vascular grafts. In vivo, endothelial cells normally produce prostacyclin (PGI2), a potent antiplatelet agent. The aim of this study was to determine whether seeded grafts show significant PGI2 production after in vivo implantation. Grafts were seeded with either autologous canine venous endothelial cells or autologous microvascular endothelial cells. After 12 weeks, PGI2 production was assessed under basal and stimulated conditions. Seeded grafts were compared with non-seeded controls and the corresponding aorta. The overall patency rate in seeded grafts was 80 per cent compared with 10 per cent in non-seeded grafts (P < 0.01). Grafts seeded with cells from either source produced significantly more PGI2 than unseeded grafts in both basal and stimulated states (P < 0.05). The aorta produced significantly more PGI2 than seeded grafts under both conditions (P < 0.01). Endothelial cell seeding produces a functional graft and leads to an improved patency rate.


Serotonin-induced contractility in human saphenous vein is inhibited by naftidrofuryl.

Vascular endothelial denudation contributes to vasospasm by causing platelet aggregation and the subsequent release of vasoconstrictors such as serotonin. It has recently been suggested that naftidrofuryl fumarate (NFT) may oppose serotonin-induced vasoconstriction. Fourteen rings of human saphenous vein from 14 patients undergoing varicose vein surgery were tested in standard organ bath experiments. Cumulative dose-response curves and maximal contraction in response to serotonin were recorded and this was repeated in the presence of NFT at 10(-6) and 10(-3) mol/l. The difference in maximal contractility between the three sets of curves was significant (P < 0.0001). Sensitivity to serotonin in each of the three curves was measured using the concentration for half-maximal response; differences were again significant (P < 0.0001). It is concluded that NFT reduces serotonin-induced contractility in a dose-dependent fashion in rings of human saphenous vein in vitro. These results suggest a possible role for NFT in reducing vasospasm and support further investigation of this drug.


Parotidectomy for parotid tumours: 19-year experience from The Netherlands.

A total of 150 patients were treated for parotid tumours over a period of 19 years. In 94 per cent superficial or total parotidectomy was performed. Histological diagnosis of the resected specimen revealed pleomorphic adenoma in 92 patients (61 per cent), Whartin's tumour in 30 (20 per cent), various benign neoplasms in 11 (7 per cent) and malignant tumour in 17 (11 per cent). After a mean follow-up of 7.7 years, no recurrence of a benign tumour was seen. Malignant tumours recurred in five patients. Permanent partial facial paralysis was seen in 4 per cent of patients after surgery for benign lesions. Frey's syndrome was observed in 43 per cent of patients, and was not prevented by resection of the auriculotemporal nerve.


Meal area index: a new technique for quantitative assessment in achalasia by ambulatory manometry during eating.

Ambulatory non-perfused oesophageal manometry was used to study oesophageal body function during consumption of a full meal in patients with achalasia. A measure of oesophageal body activity (the meal area index) was developed by calculating the total area under the pressure curve during eating, above the preprandial baseline oesophageal pressure, per meal minute. Untreated patients with achalasia (n = 13) were compared with normal subjects (n = 42), patients with benign stricture (n = 9) and patients with achalasia who had undergone Heller's myotomy (n = 17). The results showed a high meal area index in achalasia, due to a rise in baseline oesophageal pressure and frequent high-amplitude contractions during eating. This was not seen in normal subjects or patients with stricture. The high meal area index was abolished by successful Heller's myotomy but remained in two patients with persisting dysphagia. Sustained high intraoesophageal pressure is generated during consumption of a solid meal in untreated achalasia, resulting in a unique manometric profile. Manometry during eating using the meal area index permits quantitative assessment of oesophageal body function in achalasia and may aid in the assessment of response to treatment.


Closure of laparotomy wounds: skin staples versus sutures.

To investigate the routine use of a skin stapling device for the closure of midline abdominal wounds, 48 patients were randomized to receive skin staples or subcuticular polydioxanone sutures. The mean (range) time for closure with staples was 8.0 (3.4-14.8) s cm-1 while subcuticular closure took 12.7 (9.6-28.0) s cm-1. The mean time saved per patient with skin staples was 77 s. Wound pain and requirements for analgesia were significantly lower in the sutured group. The mean cost per patient was 1.41 pounds for subcuticular closure and 7.72 pounds for stapling; the latter also incurred an additional cost of 6.27 pounds for staple removal. No clear benefit derives from the use of staples in the closure of abdominal wounds.


Evaluation of routine upper digestive tract endoscopy before laparoscopic cholecystectomy.

Endoscopy of the upper digestive tract was performed in 376 patients with symptomatic gallstone disease before elective laparoscopic cholecystectomy. Abnormalities were found in 60 patients (16.0 per cent); these included peptic ulcer (n = 14), gastric erosions (n = 15) and oesophagitis (n = 11). Thirty patients were treated medically and two by endoscopic polypectomy. In four patients endoscopy led to cancellation of cholecystectomy; in two the complaints have persisted. Statistical analysis of 28 variables showed few significant differences in symptoms between patients with normal and those with abnormal appearances at endoscopy. It is concluded that routine endoscopy before laparoscopic cholecystectomy is neither clinically useful nor cost effective in patients with symptomatic gallstone disease. This conclusion is related exclusively to patients with typical gallstone symptoms according to the definition used in this department.


Significance of intracystic pressure in abdominal hydatid disease.

A prospective study was performed in 32 patients (24 female, eight male) with 50 abdominal hydatid cysts, to assess whether intracystic pressure (ICP) could predict viability. The median ICP, measured during operation, was 35 cmH2O for 31 viable cysts and zero for nine non-viable cysts located in the liver (P < 0.05). The median ICP was significantly higher in cysts located in the left lobe of the liver than in those in the right (P < 0.05). The ICP was not significantly different in unilocular or multilocular cysts. ICP increased as the diameter of the cysts increased. The sensitivity of the indirect haemagglutination test was 86 per cent and the specificity 75 per cent. It is concluded that measurement of ICP is a simple and reliable method for assessment of the viability of abdominal hydatid cysts.


Open method versus capsulorrhaphy without drainage in the treatment of children with hepatic hydatid disease.

A recognized major postoperative complication of hepatic hydatid disease is accumulated hydrops leading to secondary infection in the residual cavity of the excised cyst. This study examined two methods of treating cystic hepatic hydatid disease in 43 children. A group of 22 children were treated by a new method of open drainage, 21 underwent capsulorrhaphy without drainage. There was no mortality or morbidity. The open method was associated with more rapid resolution of hydrops and quicker shrinkage of residual cavities, with efficacy over a median follow-up of 42 months.


In vivo assessment by videomicroscopy of acute renal microvascular responses to cyclosporin.

Nephrotoxicity limits the use of cyclosporin A for immunosuppression after organ transplantation and may be caused by glomerular hypoperfusion. Indirect studies have shown that cyclosporin A increases renal vascular resistance and reduces total renal blood flow. This study used direct in vivo videomicroscopy to define the effects of the drug on the renal microcirculation of the rat. An intravenous infusion of cyclosporin A (20 mg per kg body-weight) caused a 13 per cent acute constriction of the proximal interlobular artery and an associated 29 per cent reduction in preglomerular interlobular arterial blood flow. There was a simultaneous increase in mean arterial blood pressure of 34 per cent caused by cyclosporin A and a 23 per cent increase in systemic vascular resistance. Cyclosporin acutely reduces renal microvascular blood flow by vasoconstriction and affects the central circulation, suggesting that a generalized peripheral vasoconstriction is induced.


Liver transplantation for fulminant hepatic failure and late-onset hepatic failure in children.

The mortality rate of fulminant hepatic failure (FHF) and late-onset hepatic failure (LOHF) in childhood has remained between 70 and 95 per cent despite recent improvements in medical therapy. Liver transplantation has become an important therapeutic option in adults with this condition but has been performed infrequently in children. Between March 1988 and August 1991, 12 children aged between 1 month and 14 years with FHF or LOHF received 13 liver transplants. The aetiology was viral hepatitis in eight children (non-A non-B in six, A in two), drug hepatotoxicity (carbamazepine) in two, autoimmune hepatitis in one and congenital haemochromatosis in one. Reduced-size livers were used for ten of the 13 transplants. Morbidity after operation included infective complications and abdominal bleeding. Two patients died from graft versus host disease, one from brain aspergillosis and another from graft infarction after portal vein thrombosis. Eight patients survive after a median follow-up of 18 months. Liver transplantation should be the therapeutic choice for children with FHF and LOHF for whom the chances of recovery are poor.


Toxic dilatation of the colon in Chagas' disease.

Toxic megacolon occurs in colitis of differing aetiology. This report describes 15 patients with chagasic megacolon with this complication. The clinical signs and symptoms in all patients were pain and progressive abdominal distension accompanied by fever, severe toxaemia and shock. Seven patients developed this clinical pattern after manual removal of faeces. The remaining patients had pain and abdominal distension followed by signs of severe toxaemia when first examined. Nine patients underwent total colectomy with ileostomy (one death), four partial colectomy (all died) and two received medical treatment (both died). At autopsy, three of the four patients undergoing partial colectomy had residual colitis and enteritis. The surgical procedure of choice for this complication of chagasic megacolon is total colectomy.


Mucin changes in ileoanal pouches monitored by metabolic labelling and histochemistry.

The pattern of mucin synthesis and secretion in mucosal biopsies from the proximal ileum, distal ileum, rectum and pouch before and after ileostomy closure was monitored in patients undergoing restorative proctocolectomy by metabolic labelling with [3H]glucosamine and [35S]sulphate and compared with the mucin histochemistry in each patient. Metabolic labelling clearly demonstrated a reduction in sulphation associated with the rectal mucosa in colitis. Significant differences in the turnover of isolated secreted mucin between proximal and distal ileum and rectum were also found, as was a metaplastic change towards a colonic-type mucosa in the pouch before and after ileostomy closure relative to the proximal and distal ileum, and rectum. This technique can be used to monitor colonic metaplasia in the pouch mucosa and is suitable for comparative studies where mucin changes are implicated.


Evidence from dynamic integrated proctography to redefine anismus.

The role of anismus in the aetiology of defective rectal evacuation was investigated by dynamic integrated proctography in 20 controls and 71 constipated patients. Normal parameters were defined and compared between 21 constipated patients with poor evacuation during proctography (< 40 per cent of contrast evacuated; group 1) and 50 who evacuated fully (> 90 per cent of contrast evacuated; group 2). Nine patients in group 1 failed to evacuate. Radiological abnormalities of the rectum were recorded in all groups but obstructed evacuation was not observed. Anismus (defined as a recruitment of puborectalis electromyogram (EMG) activity of > 50 per cent) was significantly more common in group 1 than group 2 patients (14 of 21 versus 12 of 50, P < 0.01) and present in seven of those unable to evacuate. Eight patients in group 1 failed to raise intrarectal pressure > 50 cmH2O compared with two in group 2 (P < 0.001). Six patients in group 1 demonstrated both anismus and inability to raise intrarectal pressure, which may combine to cause defective evacuation. EMG recruitment alone is insufficient to diagnose anismus. Definition should be based on three criteria: demonstration of puborectalis EMG recruitment of > 50 per cent; evidence of an adequate level of intrarectal pressure (> 50 cmH2O) on straining; and presence of defective evacuation.


General surgery in patients aged 80 years and older.

This study reviews 594 surgical admissions, of patients aged 80 years and older, to departments of general surgery during 1 year. Half of the patients were admitted as emergencies and 60 per cent underwent surgery. The operative mortality rate was 8 per cent and the overall mortality rate for all admissions 9 per cent. The number of complications and the mortality rate after surgery increased in emergency cases and in patients with coexisting disease. Of all admissions, 72 per cent were uncomplicated and in 70 per cent patients could be discharged directly home; such patients do not generally take up beds and are discharged as soon as medical care is no longer indicated. The number of admissions of patients over 80 years of age will increase by about 30 per cent during this decade and, unless additional resources are provided to meet this challenge, new standards must be considered for the distribution of resources and of indications for surgery in both young and old.


Research on avian coccidia: an update.

Despite the availability of many anticoccidial drugs, infections caused by species of Eimeria continue to be a source of significant economic loss to the poultry industry. After two decades in which the use world wide of ionophorous antibiotics gave unparalleled control of coccidiosis, drug resistance is once again tipping the balance in favour of the parasites. The realization that even the most spectacularly successful drugs might, after all, have a finite life if not used conservatively, has focused attention on ways in which the life span of drugs can be prolonged. Many drugs with different (if unknown) modes of action are available, and a variety of shuttle and rotation programmes can be considered. In view of the limitations of chemotherapy, particularly for the rearing of replacement flocks, there is considerable interest in the development of vaccines. Prospects for the introduction of live vaccines based on attenuated parasites are now very good, but the availability in the future of genetically engineered vaccines is more uncertain as little is known about the parasite molecules that stimulate protective immunity and, even if isolated, how they can be administered to the host so that it responds in the immunologically correct manner. Current research on Eimeria spp. in the chicken is broadly representative of that being done on other coccidia. Many lines of investigation are not connected with the development of new drugs or vaccination per se (and therefore have no obvious practical applications), but they are providing new insights into the biological complexity of the organisms and the ways in which they interact with their hosts. It remains possible, however, that a more detailed understanding and analysis of the molecules that are essential in the maintenance of the parasitic life style can be exploited in the future to provide alternative targets for chemical or immunological attack. The research topics considered in this review are arbitrarily grouped as studies on: (1) the basic biology of parasites, including aspects of the life cycle, and structure and function of the apical organelles; (2) the molecular biology of the parasites, including analyses of the number and structure of chromosomes, characterization of DNA sequences, and an account of the viral RNA that has been found in some species of Eimeria; and (3) control of coccidiosis, encompassing first immunity and the development of vaccines, and secondly, chemotherapy.


The comparative effectiveness of three commercial oral solutions in correcting fluid, electrolyte and acid-base disturbances caused by calf diarrhoea.

Three commercial oral rehydration solutions (Effydral ('E'), Lectade ('L') and Lectade Plus ('LP')) were evaluated in young calves with diarrhoea following the administration of E. coli. Twenty calves with non-fatal diarrhoea were included in each group and examined for electrolytes, acidosis (pH, PCO2 and TCO2), PCV and selected biochemical parameters. Faecal consistency and clinical state were also assessed. Eight calves were examined for plasma and ECF volume. Calves were treated with the appropriate ORS only for 2 days and with ORS plus milk substitute for a further 2 days. No other treatments were given. Solutions E, L and LP were chosen specifically to test the hypothesis that their ability to repair extracellular volume would depend on their sodium content (E > L > LP) and their ability to correct metabolic acidosis would reflect their content of bicarbonate precursor (E > LP > L). Both hypotheses were confirmed as was the fact that the higher sodium content of E helps it to repair ECF volume without predisposing to hypernatraemia. The importance of correcting hyponatraemia as well as ECF volume is emphasized. Direct measurement of such changes proved much more sensitive than traditional clinical parameters such as weight loss, skin elasticity, etc. Although this study was not designed to examine mortality, it is noted that nine treated calves died, none in the E-treated group.


Colonization of neonatal puppies by staphylococci.

The composition of the normal staphylococcal flora of bitches and their litters held in a breeding unit was studied. The animals were sampled at a number of sites using moistened swabs. Six bitches were sampled daily, for 10 days, before whelping and then, together with four puppies per litter, at whelping (day 11) and at 1 and 7 days thereafter. Staphylococcus intermedius formed the predominant staphylococcal isolate. S. intermedius counts at the oral and nasal sites on the bitches did not change markedly before whelping and remained low (< 6 cfu/swab). Significant rises in the oral counts on both the bitches (P < 0.05) and puppies (P < 0.001) were then observed after whelping (days 11-18). Abdominal counts on both the bitches and puppies also rose (P < 0.001) after whelping. S. intermedius counts at the vaginal vestibulum of the pregnant bitches were found to be higher than at any other site sampled and did not alter markedly until whelping when a decrease (P = 0.05; days 10-12) was observed. S. intermedius was not found at the anal site in any of the six bitches and only transiently colonized five of the puppies.


Effects of spatial allowance, group size and perches on the behavior of hens in cages with nests.

The behaviour of laying hens housed in 'welfare-improved' cages fitted with one nest per hen was investigated with manipulations of group size (two or four birds), spatial allowance excluding the nests (600 cm2 or 1200 cm2 per bird) and perch provision (presence or absence). More time was spent in the nests by birds housed at 600 cm2 than at 1200 cm2, and by birds housed in pairs than in four. Perch provision had no significant effect on time spent in the nest but resulted in reduced nest soiling by birds housed at 1200 cm2, and increased 'comfort' behaviour by some groups.


Analysis of the camelpox virus thymidine kinase gene.

The thymidine kinase (TK) gene from camelpox virus has been cloned using the polymerase chain reaction (PCR). The oligonucleotides used in the PCR amplification were based on residues conserved amongst the orthopoxviruses on the 5' and 3' sides of the TK gene. The oligonucleotides were also designed to contain HindIII cleavage sites to facilitate subsequent cloning. A fragment of approximately 700 base pairs was amplified from camelpox virus infected tissue culture cells. This fragment was then cleaved with HindIII and cloned into the M13mp19 sequencing vector which had also been cut with HindIII. The nucleotide sequence of the TK gene was then determined and compared to other poxvirus TK sequences. The possibilities of producing TK- camelpox virus vaccines and of using camelpox virus as a vaccine vector for the expression of genes from other camel pathogens are discussed.


Campylobacter infections in calves, piglets, lambs and kids in Trinidad.

Faeces or rectal swabs from 689 diarrhoeic and non-diarrhoeic animals were cultured for thermophilic campylobacters and their antibiograms were determined. Three hundred and fifteen (45.7%) samples were positive for Campylobacter. Piglets had the highest prevalence, 79.3% (233/294) and lambs, the lowest with 17.9% (15/84) being positive. The difference was statistically significant (P < or = 0.01; chi 2). In calves, 20.5% (60/293) and in kids 38.9% (7/18) were positive for campylobacters. The prevalence of infection was not significantly (P > or = 0.05; chi 2) different between diarrhoeic (46.1%) and non-diarrhoeic (45.1%) animals nor between male (47.5%) and female (43.8%). The frequency of isolation of campylobacters harvested from semi-intensively managed animals (75.4%) was, however, significantly higher (P < or = 0.001; chi 2) than from intensively or extensively managed animals. Overall, C. coli strains (32.8%) were more frequently isolated than C. jejuni strains (12.9%) and the difference was significant (P < or = 0.001; chi 2). Biotype I accounted for 67.3% (152/226) of C. coli and 64.0% (57/89) of C. jejuni strains isolated. A total of 245 (77.8%) strains of Campylobacter exhibited resistance to one or more antibiotics and was highest to streptomycin (76.5%), kanamycin (28.6%) and neomycin (26.7%). It was concluded that Campylobacter infections were widespread in livestock in Trinidad, particularly C. coli in piglets.


Bulk and trace elements in the accessory glands of buffalo bulls.

Little is known of the importance of mineral levels in buffalo semen or the relationship of the level of various elements to spermatozoan activity. To establish a basis upon which further studies could be conducted, the accessory glands (seminal vesicles, prostate and bulbo-urethrals) of 43 buffalo bulls (2-4 years old) with intact testes and eight steers (3-4 years old) were analysed for their content of bulk and trace elements. The ash obtained from known weights of various accessory glands was used to determine the concentrations of Na and K using emission flame photometry. P was determined chemically, whereas Ca, Mg, Cu, Fe and Zn were assayed by atomic absorption spectrophotometry. The accessory glands of intact bulls varied significantly in the concentration of all elements except Fe. Ca and Cu were relatively more concentrated in the seminal vesicles. The prostate had the highest concentration of Zn, while the highest concentrations of Na, K, Mg and P were found in the bulbo-urethral glands. Age of the bulls had no marked effect on any of the elements studied except Cu which appeared to decrease significantly in older bulls. Seasonal variation was significant for the levels of K, Ca and Zn. Castration appeared to result in a highly significant reduction of Zn concentration in all accessory glands.


Single neuron gustatory responses of the gerbil chorda tympani to a variety of stimuli (recorded by a new method).

In most mammalian studies on gustatory single neuron recordings, the animal's chorda tympani nerve was cut and manipulated. This results in nerve trauma which may have affected the precision of the responses. In this paper, we are presenting a method whereby gustatory recordings were obtained from gerbil single chorda tympani neurons by inserting a microelectrode directly into the uncut nerve. The stimuli included 0.3 M NaCl, 0.3 M KCl, 0.3 M CaCl2, 0.3 M NH4Cl, 0.05 M acetic acid, 0.01 M quinine HCl, 32% Polycose and the sweeteners 0.5 M D-glucose, 0.5 M D-fructose, 0.02 M sodium saccharin and 0.5 M sucrose. While thirty-seven of the sixty seven neurons tested did not respond to any of the eleven gustatory stimuli applied to the gerbil's tongue, thirty positive single neuron responses were obtained to this group of compounds. The thirty positive neuron responses were grouped in two ways: (1) by observationally sorting the data according to maximum responses to four stimuli, sucrose, NH4Cl, NaCl, and acetic acid; and (2) by objectively sorting the data matrix using cluster analysis. The groups resulting from each method were then characterized and compared by discriminant function analysis. By the first grouping method, ten neurons responded best to sodium chloride, seven to acetic acid, four to ammonium chloride, and nine to sucrose. However, canonical discriminant function analysis showed that two of the four groups, acetic acid and ammonium chloride, occupied the same region of discriminant space and should be combined.(ABSTRACT TRUNCATED AT 250 WORDS)


Basal forebrain and anterior thalamic contributions to acetylcholinesterase activity in granular retrosplenial cortex of rats.

Histochemical studies demonstrate that granular retrosplenial cortex (cortical areas 29b and c) of the adult rat displays a characteristic laminar pattern of acetylcholinesterase (AChE) activity. While some AChE-positive axons are found in all cortical layers, most intense staining occurs in two bands that correspond to layers I and III. The present studies were directed toward identifying the neural systems underlying this AChE activity. Unilateral electrolytic or excitatory amino acid induced lesions of the basal forebrain, including the nucleus of the diagonal band, result in reductions of AChE staining throughout ipsilateral granular retrosplenial cortex; particularly noteworthy are the reductions in layer I and the deeper cortical layers. AChE staining remains in superficial layer I and in layer III. Placement of lesions in the anterior thalamus, including all of the anterior dorsal nucleus, results in reduction of AChE histochemical staining in the outer part of layer I and especially in layer III. Staining remains in much of layer I and in the deepest band of layer III. Placement of electrolytic lesions in the hypothalamus or the midbrain tegmentum produce no detectable change in the pattern of AChE in retrosplenial cortex. These results indicate that AChE activity in granular retrosplenial cortex is found primarily within afferent axons from the basal forebrain system and from anterior dorsal thalamus, and these two systems of afferents display distinct laminar patterns of termination.


Autoradiographic localization of the binding of calcium channel antagonist, [125I]omega-agatoxin IIIA, in rat brain.

The calcium channel antagonists omega-agatoxin IIIA (omega-Aga-IIIA) and omega-conotoxin GVIA (omega-CgTx) were radioiodinated and used to locate binding sites in the rat brain by receptor autoradiography. While patterns of regional binding to sagittal sections of rat brain were generally similar for the 2 toxins, notable differences in the cerebellum and hippocampus were observed. Specific [125I]omega-Aga-IIIA binding was greatest in the granule cell layers of the cerebellum and of the dentate gyrus. In contrast, binding of [125I]omega-CgTx was most intense in the molecular layers of these structures. Less than one-third of [125I]omega-Aga-IIIA binding in rat brain slices was inhibited by pre-exposure to 250 nM omega-CgTx, while 40 nM omega-Aga-IIIA virtually eliminated the binding of [125I]omega-CgTx under the same conditions. The P-type calcium channel antagonist omega-Aga-IVA blocked only a small fraction of [125I]omega-Aga-IIIA and [125I]omega-CgTx binding. These autoradiographic data are consistent with membrane binding experiments and indicate that the combined use of agatoxins and conotoxins may be useful in the characterization of separate types of neuronal calcium channels.


Dopamine denervation leads to an increase in the intramembrane interaction between adenosine A2 and dopamine D2 receptors in the neostriatum.

We have previously found, in striatal membrane preparations from young (2 months old) rats, that stimulation of adenosine A2 receptors (with the selective adenosine A2 agonist CGS 21680) increases the dissociation constants of high- (Kh) and low-affinity (Kl) dopamine D2 binding sites (labelled with the selective dopamine D2 antagonist [3H]raclopride) without changing the proportion of high affinity binding sites (Rh). In the present study in striatal preparations from adult (6 months old) rats, it was found that in addition to the increase in both Kh and Kl values, stimulation of adenosine A2 receptors is associated with an increase in Rh. These results suggest that, in the adult rat, adenosine A2 stimulation may inhibit the behavioural effects induced by dopamine D2 stimulation both by decreasing the affinity and the transduction of dopamine D2 receptors. We have also studied the intramembrane A2-D2 receptor interaction in an experimental model of Parkinson's disease, namely in rats with a unilateral 6-OH-dopamine-induced lesion of the nigro-striatal dopamine pathway. It was found that a unilateral dopamine denervation is associated with a higher density of striatal dopamine D2 receptors in the order of 20%, without any change in their affinity compared with the unlesioned neostriatum. Furthermore, the density (Bmax values) of dopamine D2 receptors in the contralateral neostriatum was significantly higher (about 20%) than in the striatum from naive animals. This finding suggests that an unilateral dopamine denervation also induces compensatory long-lasting changes of dopamine D2 receptors in the contralateral neostriatum.(ABSTRACT TRUNCATED AT 250 WORDS)


The 5-hydroxytryptamine agonist fenfluramine increases Fos-like immunoreactivity in the brain.

This study was designed to assess the effects of the 5-hydroxytryptamine (5-HT) indirect agonist fenfluramine on the brain distribution of Fos- and corticotropin-releasing factor-like immunoreactivity (F-LI and CRF-LI). A single intraperitoneal injection of either DL-fenfluramine (25 mg/kg) or saline was given to resting Sprague-Dawley rats housed on a 12-12 h light-dark cycle and fed libitum. Sixty min following injections, rats were killed and brains removed and sliced (40 microns thick) in a coronal plane from the anterior olfactory bulb to the brainstem. Brain slices were then stored at -40 degrees C pending the tissue localization of F-LI and CRF-LI. F-LI and CRF-LI were determined by means of a double immunostaining procedure using the peroxidase-avidin:biotin complex (ABC) method. Fenfluramine injection led to a marked increase in F-LI in the caudate-putamen (CPu), the parvocellular division of the hypothalamic paraventricular nucleus (PVN), and the central amygdaloid nucleus (CeA). In the PVN, most of the F-LI was co-localized with CRF-LI. There was no attempt to identify which types of neurons displayed F-LI in CPu and CeA. While F-LI was readily observable in all rats treated with fenfluramine, it was not discernible in the control animals. This study provides evidence for an involvement of the immediate-early genes c-fos in the central action of fenfluramine.


The effect of sodium valproate on extracellular GABA and other amino acids in the rat ventral hippocampus: an in vivo microdialysis study.

We report the effects of i.p. administration of sodium valproate (VPA) on extracellular concentrations of various amino acids in the rat ventral hippocampus studied using in vivo microdialysis, followed by HPLC with fluorometric detection. At the doses used (100, 200 and 400 mg/kg), VPA had no effect on extracellular aspartate, glutamine and taurine, whilst inducing a small, but not statistically significant increase in glutamate at 200 and 400 mg/kg. In contrast, VPA administration produced a biphasic effect on extracellular GABA levels which was dependent on the dose used. At 100 mg/kg, VPA reduced GABA concentrations by 50% when compared to basal. 200 mg/kg VPA had virtually no effect, whilst 400 mg/kg VPA raised extracellular GABA levels to 200% of basal. The results are discussed in relation to the known pharmacological and anticonvulsant actions of VPA.


Blockade of mitral/tufted cell habituation to odors by association with reward: a preliminary note.

Association of odor and reward during the early postnatal period modifies rat pup behavioral responses and olfactory bulb neural responses to subsequent presentations of that odor. Recent evidence has shown that olfactory bulb output neurons, mitral/tufted cells, receive convergent odor and reward inputs. The present report demonstrates that contiguous odor-reward pairings prevent mitral/tufted cell habituation to the odor that normally occurs to repeated odor-only stimulation. It is hypothesized that the maintenance of olfactory bulb responses to conditioned odors during training may allow for activation of long-term memory mechanisms.


Frequency-dependent increase in cortical acetylcholine release evoked by stimulation of the nucleus basalis magnocellularis in the rat.

Acetylcholine was collected from the somatosensory cortex of anesthetized rats, using the microdialysis technique. Electrical stimulation of the nucleus basalis magnocellularis (NBM) with trains of 10 pulses at 100 Hz delivered every second produced a 3-4-fold increase in acetylcholine release. Stimulation with an intratrain frequency of 10, 50, 100 or 200 Hz demonstrated that 100 Hz trains produced the greatest increase, while the other frequencies were about half as effective. The cortical release of acetylcholine in this paradigm supports the hypothesis that the previously demonstrated enhancement by NBM stimulation of cortical sensory inputs is due to cholinergic activation.


Trigeminal ganglion neurons which project by way of axon collaterals to both the caudal spinal trigeminal and the principal sensory trigeminal nuclei.

Employing a combination of fluorescent retrograde double labeling and immunofluorescence histochemistry, we found that some single neurons in the trigeminal ganglion of the rat projected by way of axon collaterals both to the caudal spinal trigeminal nucleus and to the principal sensory trigeminal nucleus, and that about 40% or 57% of these neurons showed respectively substance P- or calcitonin gene-related peptide-like immunoreactivity.


Origin of the in vivo rat piriform cortex activity recorded with voltage-sensitive dyes: comparison of the optical signals and the field potentials.

The comparison of optical recordings and evoked field potentials recorded on the rat piriform cortex pointed out that both signals were strongly correlated. As the field potentials, the two waves of the optical signals originated from the mono- (direct olfactory bulb afferents) and polysynaptic (intrinsic association fibers) excitatory postsynaptic potentials. Such optical recordings will be used for studying spatiotemporal distribution of the piriform cortex activity.


K+ and pH homeostasis in the developing rat spinal cord is impaired by early postnatal X-irradiation.

Activity-related transient changes in extracellular K+ concentration ([K+]e) and pH (pHe) were studied by means of ion-selective microelectrodes in neonatal rat spinal cords isolated from pups 2-14 days of age. Pups 1 to 2 days old were X-irradiated to impair gliogenesis and spinal cords were isolated 2-13 days postirradiation (PI). In 2- to 14-day-old pups PI stimulation produced ionic changes that were the same as those in 3- to 6-day-old control (non-irradiated) pups; e.g. the [K+]e increased by 4.03 +/- 0.24 mM (mean +/- S.E.M., n = 30) at a stimulation frequency of 10 Hz and this was accompanied by an alkaline shift of 0.048 +/- 0.004 pH units (mean +/- S.E.M., n = 32) pH units. By contrast, stimulation in non-irradiated 10- to 14-day-old pups produced smaller [K+]e changes, of 1.95 +/- 0.12 mM (mean +/- S.E.M., n = 30), and an acid shift of 0.035 +/- 0.003 pH units which was usually preceded by a scarcely discernible initial alkaline shift, as is also the case in adult rats. Our results show that the decrease in [K+]e ceiling level and the development of the acid shift in pHe are blocked by X-irradiation. Concomitantly, typical continuous development of GFAP-positive reaction was disrupted and densely stained astrocytes in gray matter of 10- to 14-day-old pups PI revealed astrogliosis. In control 3- to 6-day-old pups and in pups PI the stimulation-evoked alkaline, but not the acid, shift was blocked by Mg2+ and picrotoxin (10(-6) M). The acid shift was blocked, and the alkaline shift enhanced, by acetazolamide, Ba2+, amiloride and SITS. Application of GABA evoked an alkaline shift in the pHe baseline which was blocked by picrotoxin and in HEPES-buffered solution. By contrast, the stimulus-evoked alkaline shifts were enhanced in HEPES-buffered solutions. The results suggest a dual mechanism of the stimulus-evoked alkaline shifts. Firstly, the activation of GABA-gated anion (Cl-) channels induces a passive net efflux of bicarbonate, which may lead to a fall in neuronal intracellular pH and to a rise in the pHe. Secondly, bicarbonate independent alkaline shifts may arise from synaptic activity resulting in a flux of acid equivalents.


The distribution of catecholamines and beta-endorphin in the brains of three behaviorally distinct breeds of dogs and their F1 hybrids.

This study examines neurochemical and behavioral differences among three types of domestic dogs and F1 hybrids derived from them. Purebred dogs included Border Collies, representing herding dogs, Shar Plaininetz, representing livestock protecting dogs, and Siberian Huskies, representing Northern dogs. Composite behavioral scores were derived from frequency measures of various components of predatory behavior observed when the dogs were tested with mice. Catecholamine levels, including norepinephrine (NE), dopamine (DA), and epineprine (EPI), were determined in various brain regions by high-performance liquid chromatography (HPLC) with electrochemical detection. beta-endorphin levels were determined in the same regions by RIA. Collies showed the highest levels of non-consummatory behaviors and Huskies the highest levels of consummatory behaviors. Shars were found to have lower levels of NE and DA than Collies and Huskies in several brain regions, including those comprising the nigrostriatal DA system. Positive correlations between neurochemical and behavioral characteristics could be made between Shars and Collies. Comparisons of F1 hybrids with their respective parental breeds revealed no clear pattern of inheritance for these characteristics but suggested that multiple factors, both independent and epistatic, are involved. Based on previous studies on nigrostriatal DA and behavior, the levels of DA in this system may be causally related to the levels of predatory behavior expressed by Collies and Shars.


The role of angiotensin II in regulation of cerebrospinal fluid formation in rabbits.

The effect of central and peripheral administrations of angiotensin II (AII) on cerebrospinal fluid (CSF) formation was investigated in rabbits anesthetized with intravenous alpha-chloralose and urethane. CSF production was measured by the ventriculo-cisternal perfusion method with Blue dextran 2000 used as an indicator substance. AII infused intracerebroventricularly (i.c.v.) at rates of 5.5 and 55 pg min-1 significantly decreased CSF formation rate by 27% and 36%, respectively. This AII action could be completely blocked by simultaneously administered specific AII antagonist, [Sar1,Ala8]AII (saralasin), given i.c.v. at a rate of 5.5 ng min-1. Intracerebroventricular infusion of AII at a rate of 5.5 ng min-1 did not change CSF production. Saralasin, when given alone into the ventricular system (5.5 ng min-1), non-significantly increased CSF production by 12%. However, in 4 of the 6 animals studied, the rise in CSF production was statistically significant (by 23%). Intravenous infusion of AII at rates of 30 and 100 ng kg-1 min-1 was found not to change CSF formation rate. Also, i.c.v. administration of angiotensin I converting enzyme inhibitor, captopril (10 microliters min-1), did not influence CSF production. It is concluded that the centrally released AII can control CSF production. Our results suggest that under normal conditions, AII exerts a tonic inhibitory effect on CSF formation. In contrast, the blood-borne peptide seems not to influence this physiological process.


Cholecystokinin antagonists inhibit in vivo voltammetric signals generated by KCl-induced slow wave depolarization in rat caudate.

The effect of sulfated cholecystokinin octapeptide (CCK-8S) on the generation of slow wave depolarisation in the rat caudate-putamen (CPu) was studied using in vivo voltammetry. Pressure-ejection of 50 microM CCK-8S into the CPu induced voltammetric signals recorded at widely spaced Nafion-coated carbon fiber microelectrodes. Based on the in vitro selectivity properties of the electrodes, the signals were predominantly due to increases in extracellular concentrations of dopamine (DA). The similar propagation rates of the signals induced by CCK-8S and 100 mM KCl suggests that the CCK-8S-induced signals represent a slow wave depolarization (SWD). Since the CPu was refractory to a second CCK-8S stimulus, the effects of CCK antagonists on DA signals associated with 100 mM KCl-induced SWD were evaluated. Proglumide (4-64 mg/kg) and lorglumide (20-640 micrograms/kg), administered intravenously, decreased KCl-induced DA signals in the CPu in a dose-dependent manner. The antagonistic effect of lorglumide on the KCl-induced signals was partly reversed 130 min after drug administration. The generation of a SWD by CCK-8S and the inhibitory effects of CCK-8S antagonists on KCl-induced signals suggest that the susceptibility of the CPu to KCl-induced SWD may be enhanced by CCK-8S.


Developmental expression of brain beta-spectrin isoform messenger RNAs.

We have investigated the expression of brain beta SpIIa and beta SpIb (previously referred to as the beta-subunits of brain spectrin (240/235) and brain spectrin (240/235E), respectively) during mouse brain development. The 9 kb transcript which encodes beta SpIIa is present in fetal mouse brain tissue and increases to a maximal level in a 30-day-old mouse. There is a coordinate accumulation of the 7.8 kb alpha SpIIa mRNA (with beta SpIIa) during mouse brain development. The coordinate expression of alpha SpIIa and beta SpIIa at the mRNA and protein level allows formation of (alpha SpIIa/beta SpIIa)2 tetramers (brain spectrin(240/235)) early in premitotic neuronal development; and avoids turnover of unassembled alpha and beta-subunits. An 11 kb transcript which encodes beta SpIb is not produced in embryonic tissue, and is first seen in a 6-day-old mouse. The protein translation products beta SpIIa and beta SpIb have previously been demonstrated by our laboratory to first appear in fetal mouse brain tissue and at postnatal day 6-8, respectively [J. Neurosci., 7 (1987) 864-874]. The expression of beta SpIb mRNA on postnatal day 6-8, and the appearance of brain spectrin(240/235E) in postmitotic and postmigratory neurons of the cerebellum at this same time; suggests that brain spectrin(240/235E) is involved in differentiated functions of the neuron (formation of cell-cell contacts, formation of dendritic processes and postsynaptic contacts). Thus, the data from the present study demonstrates that the expression of these two neuronal beta-spectrin isoforms is regulated at the level of mRNA expression.