Weight loss effects from vegetable intake: a 12-month randomised controlled trial.

BACKGROUND/OBJECTIVES: Direct evidence for the effects of vegetable intake on weight loss is qualified. The study aimed to assess the effect of higher vegetable consumption on weight loss. SUBJECTS/METHODS: A single blind parallel controlled trial was conducted with 120 overweight adults (mean body mass index=29.98 kg/m(2)) randomised to two energy deficit healthy diet advice groups differing only by doubling the serving (portion) sizes of vegetables in the comparator group. Data were analysed as intention-to-treat using a linear mixed model. Spearmans rho bivariate was used to explore relationships between percentage energy from vegetables and weight loss. RESULTS: After 12 months, the study sample lost 6.5±5.2 kg (P<0.001 time) with no difference between groups (P>0.05 interaction). Both groups increased vegetable intake and lost weight in the first 3 months, and the change in weight was significantly correlated with higher proportions of energy consumed as vegetables (rho=-0.217, P=0.024). Fasting glucose, insulin and triglyceride levels decreased (P<0.001 time) and high-density lipoprotein cholesterol levels increased (P<0.001 time), with no difference between groups. Weight loss was sustained for 12 months by both groups, but the comparator group reported greater hunger satisfaction (P=0.005). CONCLUSIONS: Advice to consume a healthy low-energy diet leads to sustained weight loss, with reductions in cardiovascular disease risk factors regardless of an emphasis on more vegetables. In the short term, consuming a higher proportion of the dietary energy as vegetables may support a greater weight loss and the dietary pattern appears sustainable.

VEGF-induced choroidal damage in a murine model of retinal neovascularisation.

BACKGROUND/AIMS: Photoreceptor-specific upregulation of vascular endothelial growth factor (VEGF) in a transgenic mouse model (Kimba) of retinal neovascularisation induces retinal vascular damage which appears similar to that in diabetic retinopathy. Here we have determined whether the choroidal vasculature is also affected in Kimba. METHODS: Kimba mice were assessed with fundus fluorescein angiography for mild, moderate or severe retinal vascular leakage prior to preparation of choroidal corrosion casts for quantitative analysis using scanning electron microscopy. VEGF was located immunohistochemically. RESULTS: Choroidal abnormalities included microaneurysms, constriction, shrinkage and dropout in the capillaries and tortuosity and loops in the arteries and veins which were similar to those observed in corrosion casts of the human choroid in diabetes. Similar to human diabetes, choroidal neovascularisation was not observed. The severity of choroidal damage correlated with the extent of retinal vascular leakage. In addition to the expected presence of VEGF in photoreceptors, VEGF was also detected in the pigment epithelium and choroid in the transgenic mice. CONCLUSION: We show that elevated retinal VEGF levels trigger pathophysiological changes in the choroid. We suggest that therapies to prevent vascular damage in diabetes must target both the retinal and choroidal vasculatures.

EphA/ephrin-A interactions during optic nerve regeneration: restoration of topography and regulation of ephrin-A2 expression.

During visual system development, interactions between Eph tyrosine kinase receptors and their ligands, the ephrins, guide retinal ganglion cell (RGC) axons to their topographic targets in the optic tectum. Here we show that Eph/ephrin interactions are also involved in restoring topography during RGC axon regeneration in goldfish. Following optic nerve crush, EphA/ephrin-A interactions were blocked by intracranial injections of recombinant Eph receptor (EphA3-AP) or phospho-inositol phospholipase-C. Topographic errors with multiple inputs to some tectal loci were detected electrophysiologically and increased projections to caudal tectum demonstrated by RT-97 immunohistochemistry. In EphA3-AP-injected fish, ephrin-A2-expressing cells in the retino-recipient tectal layers were reduced in number compared to controls and their distribution was no longer graded. The findings, supported by in vitro studies, implicate EphA/ephrin-A interactions in restoring precise topography and in regulating ephrin-A2 expression during regeneration.

The cardiac innervation of a marsupial heterotherm, the fat-tailed dunnart (Sminthopsis crassicaudata).

This study investigated the pattern of autonomic innervation of the heart of the fat-tailed dunnart (Sminthopsis crassicaudata) using isolated cardiac preparations. While the pattern of autonomic innervation of the atria was consistent with that found in other mammals, the ventricles displayed an unusual pattern of mammalian cardiac innervation. Transmural stimulation of the intramural nerves of isolated right ventricular preparations caused a decrease in the force of contraction of 46.8+/-3.2% followed by a rebound increase in the force of contraction beyond basal levels of 40.9+/-6.9%. These responses could be blocked independently by the application of the muscarinic receptor antagonist hyoscine and beta-adrenoreceptor antagonist propranolol respectively and could also be mimicked by the application of the agonists acetylcholine (Ach) and noradrenaline (NA). These findings indicated the presence of a functional cholinergic innervation of the ventricles that was capable of reducing the force of contraction below basal levels. This pattern of innervation has only been found previously in one other mammal, the bent-winged bat (Miniopterus schreibersii). Given that both of these species are heterotherms, it is possible that such a pattern of innervation may relate to the control of cardiac output during torpor. These findings are the first that demonstrate the homogeneity of a physiological control mechanism in a so-called 'shallow, daily torpidator' (S. crassicaudata) and a 'deep hibernator' (M. schreibersii) that is absent in mammalian homeotherms. These findings are consistent with recent work suggesting that there may be little difference between these types of heterothermy.

The microanatomy of the rectal salt gland of the Port Jackson Shark, Heterodontus portusjacksoni (Meyer) (Heterodontidae): suggestions for a counter-current exchange system.

A comprehensive anatomical study was undertaken to examine the rectal salt gland in the Port Jackson shark, Heterodontus portusjacksoni, a shark known to invade estuarine environments. The microstructure and vascular organisation of the rectal salt gland was investigated using histological observation and scanning electron microscopy of vascular corrosion casts. Cellular specialisation was observed in the lining of the central lumen of this gland. This may indicate that there is some modification of the principal product of the gland prior to its secretion. The rectal salt gland has a complex structure related to its function. Contrary to previous reports, the flow in secretory tubules is in the opposite direction to that of the capillaries and thus constitutes a counter-current arrangement. The similarity in the organisation of the counter-current and lobulate arrangement of salt-secreting glands through phylogenetically diverse organisms, such as sharks and birds, suggests that this arrangement is important in achieving efficient salt secretion.

The unusual adrenergic-like excitatory action of acetylcholine on the ventricular cardiac muscle of the horned shark, Heterodontus portusjacksoni.

The atypical excitatory effect of acetylcholine on cardiac ventricular muscle was investigated in the horned shark, Heterodontus portusjacksoni. Electrically paced ventricular strips produced a massive 391.45% (+/-26.39%) increase in basal force of contraction in response to exogenously applied acetylcholine. The response was similar in nature to that produced by applied adrenaline, which caused a 382.52% (+/-72.47%) increase. The response to acetylcholine was blocked by the muscarinic cholinoceptor antagonist atropine and the competitive beta-adrenoceptor antagonist propranolol and was reduced by bretylium, an agent known to inhibit the release of catecholamines from adrenergic nerves. These findings strongly suggest that acetylcholine mediates a localised release of a catecholamine via muscarinic cholinoceptors in shark heart. A cholinergically controlled catecholamine store has been proposed (cholinergic-adreno complex), implying that elasmobranchs may be capable of finer control of cardiac output than has previously been suspected. This complex may represent a transitional adrenergic state between humoral and neuronal regulation. The spontaneously beating atrium showed no evidence of such an excitatory response to applied acetylcholine but produced an atropine-sensitive slowing, a response typical of other vertebrates.

Blood plasma concentrations of progesterone, sperm storage and sperm viability and fertility in Gould's wattled bat (Chalinolobus gouldii).

The fertility and viability of spermatozoa stored by male and female Gould's wattled bats, Chalinolobus gouldii, was investigated in a captive colony of ten bats (three males and seven females). Bats were housed in outdoor flight cages. Plasma progesterone concentrations, measured using double antibody radioimmunoassay, isolation experiments plus sperm motility and sperm membrane stability tests were used to evaluate the viability and fertility of stored spermatozoa. Mean plasma progesterone concentrations were lowest during midwinter (< 0.5 ng ml-1) with a 20-fold increase recorded in late winter to early spring. During pregnancy, plasma progesterone concentrations increased to about 13 ng ml-1 and returned to basal values soon after parturition. The results of the plasma progesterone assays and the isolation experiments indicate that female C. gouldii can store fertile spermatozoa for at least 33 days. The investigation of spermatozoa stored by male C. gouldii revealed that 6-7 months after peak spermatogenesis about 60% of the stored spermatozoa were motile and more than 60% had stable membranes, indicating that the spermatozoa stored by males were viable and likely to be fertile. The results of this study clearly indicate that both male and female C. gouldii are capable of storing fertile spermatozoa for prolonged periods.

Effects of sympathetic nerve stimulation on the sino-atrial node of the guinea-pig.

1. The effects of sympathetic nerve stimulation on the generation of pacemaker action potentials, recorded from the sino-atrial node of the guinea-pig, were determined by using intracellular recording techniques. 2. Trains of stimuli applied to the right stellate ganglion led to an increase in heart rate after a delay of a few seconds. During the initial phase of the tachycardia the rate of discharge of pacemaker action potentials increased and the rate of diastolic depolarization increased, but both the peak diastolic potential and the maximum rate of rise of the action potentials were reduced. During the later phase of the tachycardia the peak diastolic potential, the amplitude of the action potentials, the maximum rate of rise and the rate of repolarization of the action potentials were increased. 3. When membrane potential recordings were made from sino-atrial node cells, in which beating had been abolished by adding the organic calcium antagonist nifedipine, sympathetic nerve stimulation initiated excitatory junction potentials (EJPs) which had time courses similar to those of the tachycardias recorded from beating preparations. 4. Although both the tachycardias produced by either sympathetic nerve stimulation or added noradrenaline were largely abolished by beta-adrenoceptor antagonists, the membrane potential changes recorded during the responses to sympathetic nerve stimulation or added noradrenaline were different. Bath-applied noradrenaline caused a tachycardia which was associated with an increase in the amplitudes of pacemaker action potentials, an increase in the peak diastolic potential and a shortening in the duration of pacemaker action potentials. 5. The addition of agents which cause the accumulation of cyclic AMP in the cytoplasm of the cells produced a tachycardia which was associated with a similar sequence of changes in the membrane potentials to those produced by added noradrenaline; again the membrane potential changes produced by these agents differed from those produced by sympathetic nerve stimulation. 6. The results are discussed in relation to the idea that neurally released noradrenaline activates a set of receptors which cause tachycardia by increasing inward current flow during diastole, whereas added noradrenaline activates a set of receptors that are linked to a cyclic AMP-dependent pathway which modifies the properties of some of the voltage-dependent channels involved in pacemaking activity.

Adrenergic innervation of the heart of the bat, Miniopterus schreibersii.

The adrenergic innervation of the heart of the bat (Miniopterus schreibersii) was studied with a fluorescence histochemical technique. The appearance and distribution pattern of the terminal adrenergic nerve fibers demonstrated in the atria, sinoatrial and atrioventricular nodes, and ventricles is typically mammalian. Fine varicose adrenergic fibers run in and parallel to the ventricular muscle where they are common and uniformly distributed. Indian ink perfusion of the coronary vasculature demonstrates the high density of vessels in the ventricles, but obscures the terminal innervation of the ventricular muscle. This alone, or in combination with the apparent seasonal change in the terminal innervation of the ventricles, may explain the inability of previous workers to identify an adrenergic ventricular innervation in the bat Nyctalus noctula. The adrenergic ventricular innervation might be involved in the large increases in cardiac output associated with the commencement of flight and in the massive sympathetic activation that mediates arousal from torpor.

Somatostatin and innervation of the heart of the snake Elaphe obsoleta.

The innervation of the heart of the snake Elaphe obsoleta was examined with peptide immunohistochemistry, glyoxylic acid-induced catecholamine fluorescence, and in vitro physiological preparations. Snakes were anesthetized with Nembutal. Many somatostatin (SOM)-like immunoreactive (LI) axons were observed in the sinus venosus, atria, and ventricle. Cell bodies with SOM-LI were found in the intracardiac nerve trunks of the sinus venosus, the interatrial septum, and the atrioventricular region. The SOM-LI axons and cell bodies were not affected by 6-hydroxy-dopamine and capsaicin. They are probably intrinsic parasympathetic neurons. Adrenergic, neuropeptide Y-LI, substance P-LI, and calcitonin gene-related peptide-LI axons were found in the sinus venosus, atria, and ventricle. In spontaneously beating sinoatrial or electrically driven atrial preparations, applied SOM (6 x 10(-9) M and 6 x 10(-8) M) decreased the force of atrial contraction and/or the rate of beating. The effects of SOM were tachyphylactic. SOM had no effect on the force of contraction of the driven ventricle. Stimulation of the left and right vagus nerves elicited negative chronotropic and inotropic responses followed by poststimulus positive inotropic and chronotropic responses. Atropine abolished the inhibition, and bretylium abolished the excitation. After cholinergic and adrenergic blockade, high-frequency vagal nerve stimulation had no effect on heart rate and the force of contraction. Thus, although there is an extensive distribution of intrinsic SOM-LI neurons in the heart and although applied SOM is a potent inhibitor of rate and force, SOM in the vagal neurons does not appear to act as a direct inhibitory transmitter to the cardiac muscle or pacemaker cells.

Neural regulation of the pulmonary vasculature in a semi-arboreal snake, Elaphe obsoleta.

The innervation of the pulmonary vasculature of the semi-arboreal rat snake, Elaphe obsoleta, was examined with glyoxylic acid-induced catecholamine histochemistry, peptide immunohistochemistry, and in vitro perfusion of the pulmonary vasculature. An adrenergic innervation was present on the pulmonary artery, the smaller pulmonary arteries, the veins draining the lung, and the main pulmonary vein. Vasoactive intestinal polypeptide-like immunoreactive axons were observed on the pulmonary artery and vein, small arteries, and occasionally small veins within the lung parenchyma. A dense plexus of substance P-like immunoreactive (SP-LI) axons was observed on the distal extrinsic pulmonary artery. SP-LI axons were found on the more distal arteries within the lung parenchyma, but not on the veins. The distribution of calcitonin gene-related peptide- and SP-LI axons was similar suggesting that the axons are sensory nerves. In the perfused pulmonary vasculature, vagal stimulation caused a predominant vasoconstriction which was abolished by atropine indicating it was cholinergic in nature. A post-stimulus vasodilatation was abolished by bretylium and propranolol indicating it was adrenergic in nature. The responses to nerve stimulation were located in both the extrinsic and intrinsic pulmonary vasculature. No evidence for non-adrenergic, non-cholinergic transmission to the vascular smooth muscle was found. The extensive, functional innervation of the main pulmonary artery, as well as the more distal vasculature within the lung, may reflect adaptation to cardiovascular problems imposed by an elongated body and arboreal habits.

The effects of vagal stimulation and applied acetylcholine on the sinus venosus of the toad.

1. The effects of vagal stimulation and applied acetylcholine were compared on the isolated sinus venosus preparation of the toad, Bufo marinus. 2. The effects of applied acetylcholine and of low-frequency, or short bursts of high-frequency vagal stimulation were abolished by hyoscine. 3. When intracellular recordings were made from muscle cells of the sinus venosus, it was found that applied acetylcholine caused bradycardia and a cessation of the heart beat which was associated with membrane hyperpolarization and a reduction in the duration of the action potentials. Much of the effect of acetylcholine can be attributed to it causing an increase in potassium conductance, gK. 4. When slowing was produced by low-frequency vagal stimulation, only a small increase in maximum diastolic potential was detected. During vagal arrest the membrane potential settled to a potential positive of the control maximum diastolic potential. 5. In the presence of barium, much of the bradycardia associated with vagal stimulation persisted. Although the bradycardia produced by added acetylcholine also persisted in the presence of barium, the effects of acetylcholine that could be attributed to an increase in gK were abolished. 6. Addition of caesium ions produced bradycardia with membrane potential changes similar to those seen during vagal stimulation. 7. The results are discussed in relation to the idea that neuronally released acetylcholine reduces inward current flow during diastole. In contrast applied acetylcholine as well as reducing inward current flow during diastole also increases outward current flow by increasing gK.

Effects of vagal stimulation and applied acetylcholine on pacemaker potentials in the guinea-pig heart.

1. Intracellular recordings were made from pacemaker cells lying in the sino-atrial node of guinea-pigs. 2. Low-frequency vagal stimulation slowed the rate of generation of pacemaker action potentials; high-frequency stimulation stopped the generation of action potentials. 3. During vagal stimulation the rate of diastolic depolarization was reduced with the action potential otherwise unchanged: when the heart stopped the membrane potential of pacemaker cells settled to a value positive of the maximum diastolic potential. 4. In contrast, added acetylcholine caused membrane hyperpolarization and shortened the duration of action potentials. 5. The effects of both added acetylcholine and vagally released acetylcholine were abolished by hyoscine. 6. It is suggested that neurally released acetylcholine acts to change the balance between inward and outward current flow during diastole by modifying the properties of existing voltage-dependent channels. In contrast added acetylcholine appears to activate a different set of receptors which increase the potassium conductance of pacemaker cells.

Temperature sensitivity of cardiac muscarinic receptors in bat atria and ventricle.

In contrast to other mammals, muscarinic receptors in the bat ventricle can mediate significant decrease in basal contractile force (greater than 50%), not only at 37 degrees C but also at hibernation temperature (12 degrees C). At frequencies of contraction that approximate in vivo values for 37-12 degrees C, no significant shift in receptor affinity or maximum response to applied acetylcholine was found for either ventricular or atrial muscle. Low temperature does not appear to compromise receptor function in hibernators. The atypical cholinergic innervation of the ventricle may maintain a regulative role during hibernation.

Innervation of bat heart: cholinergic and adrenergic nerves innervate all chambers.

Adult Miniopterus schreibersii were anesthetized with chloroform, and in vitro preparations of cardiac chambers were prepared. Stimulation of intramural nerves in right ventricles paced at 6 Hz caused an inhibition (56.3 +/- 3.5% decrease on basal force) mediated by cholinergic nerves and an excitation (91.5 +/- 9.9% increase on basal force) mediated by adrenergic nerves. Mean pD2s (-log effective concentration, 50%) for ventricular beta-adrenoceptors and muscarinic cholinoceptors were 6.99 +/- 0.03 and 6.42 +/- 0.07, respectively. The inhibition of ventricular contractility, by nerve stimulation or exogenous acetylcholine, occurred even after blockade of beta-adrenoceptors. The results were comparable to those obtained on atria. In some experiments, the heart was perfused in situ and paced via electrodes on the ventricle: stimulation of the right vagus nerve decreased right ventricular contractility by up to 90%. The results show that, at least in this hibernating mammal, there is an adrenergic innervation of the ventricle. The presence of a cholinergic vagal innervation capable of inhibiting the basal force of ventricular contraction has not been shown in any other mammal.