Factors contributing towards falls in older age during overground walking have been widely studied. Stepping behaviour, balance and head posture control during stair negotiation in young adults (YA) and older adults with either lower (LROA) or higher (HROA) risk of falling during midstair negotiation have not been investigated. The aims of the thesis were threefold. Firstly, age-related changes in gaze behaviour were investigated. The main finding was that older adults fixate stair edges for longer than YA. Secondly, the effect of manipulating visual information on stepping parameters and balance control was compared between YA, LROA and HROA. For stair ascent, stepping and balance control was preserved in LROA and HROA and highlighted stair edges led to increased foot clearance in all groups. For stair descent, HROA demonstrated smaller foot clearance than LROA and highlighted stair edges improved balance in LROA and HROA. Thirdly, head posture was studied in YA, LROA and HROA. Compared to walking, LROA and HROA demonstrated more variable head posture than YA. Overall the findings suggest that adults use visual and probably proprioceptive information about stair edge locations to negotiate stairs and HROA benefited from highlighted stair edges. HROA should be included in future stair negotiation studies.

Perhexiline is an anti-anginal drug that is thought to shift myocardial metabolism from \(\beta\)-oxidation of fatty acids to glucose utilisation. An associated improvement in energy efficiency may be beneficial in ischaemia-reperfusion as an adjunct to established techniques for myocardial protection during cardiac surgery. In this thesis, I conduct a prospective double-blind randomised placebo-controlled trial of oral perhexiline in patients undergoing coronary artery surgery, obtaining samples of serum, right atrium and left ventricle. I measure the concentration of perhexiline using high performance liquid chromatography and find that although highly concentrated in the heart, it may not have reached steady-state in the ventricular myocardium. I perform enzymatic colourimetry and ultra-high resolution mass spectrometry to detect changes in carbohydrate and lipid metabolism; however, the myocardial metabolic profiles of patients on perhexiline are indistinguishable from controls. On analysing the results of the clinical trial, I find no improvement in the primary endpoint, the incidence of a low cardiac output episode, or any secondary outcomes. I conclude that preoperative oral perhexiline does not improve clinical markers of myocardial protection and despite significant accumulation in the myocardium, it has no significant effect on the measurable metabolic profile of the heart at the time of surgery.

This thesis comprises two volumes, representing the research and clinical elements submitted to the University of Birmingham in partial fulfillment of the degree of Doctor of Clinical Psychology (DClinPsy). The first volume is the research component and contains three papers. The first paper is a review of the literature from 1980 to the present day, which has examined intellectual, behavioural and psychological characteristics in participants with Sotos syndrome. The second paper is an empirical study which examines the behavioural phenotype of participants with Sotos syndrome in comparison to 3 other genetic syndromes using standardised, well validated questionnaires. The third paper summarises these in language accessible to the general public. The second volume is the clinical component containing four Clinical Practice Reports and the abstract for an oral examination. These papers represent different aspects of work conducted during clinical placements. They include a paper which formulates from two different psychological perspectives, a service evaluation, a single case experimental design and a case study.

A role for protein kinase C (PKC) in the denervation-induced supersensitivity of the rat vas deferens was investigated. Chronic, surgical denervation of the rat vas deferens (up to 8 days) resulted in tissues that produced enhanced contractile responses to norepinephrine (NE) in isolated organ baths. Single challenges of NE (10 $\mu$M) produced 0.6 $\pm$ 0.1 g of maximal tension in the control vas whereas in the paired, denervated tissue 2.2 $\pm$ 0.3 g of tension was recorded (n = 6). Cumulative concentration-effect curves to NE produced in the denervated vas deferens were shifted 18-fold to the left of the control response. Neurokinin A (NKA) responses after denervation of the tissue were not significantly different from the control. Denervation did not alter the contractile response to phorbol diacetate (PDA), a PKC activator. Pretreatment of denervated and control vas deferens with 100 $\mu$M nifedipine (a calcium channel blocker), significantly attenuated the contractile response to NE. The responses in the control tissues were depressed by 88%, those in the denervated vasa were only antagonized by 65% after nifedipine treatment. Exposure of denervated and control vas deferens to 100 $\mu$M NE resulted in no significant accumulation of diacylglycerol (DAG) from basal values. The molecular species of DAG produced after receptor stimulation, in either tissue group, were not different from those found in resting tissues. Denervation also had no effect on the binding characteristics of membrane-associated PKC when assayed using the specific ligand, ($\sp3$H) phorbol dibutyrate. The PKC activity of resting vas deferens was not altered by chronic surgical denervation. Denervated and control vas deferens that were stimulated with 100 $\mu$M NE showed a time-dependent translocation of PKC from the cytosolic to the membrane fraction of the tissue. In both tissue groups exposure to NE resulted in a 3-4 fold increase in the membrane-bound PKC activity, which remained elevated above basal values for up to 20 min. The rate of translocation of PKC was faster in denervated vasa (maximal at 5 min after NE) when compared to the control (maximal at 20 min), but the maximal amount of the enzyme activated was the same for the two tissue groups. The ability of NKA, 60 mM K$\sp+$-depolarization and PDB (PKC activator) to produce translocation of the PKC was not altered by denervation of the vas deferens. (Abstract shortened by UMI.)

The electrophysiologic technique (Reuss, L., Proc. Natl. Acad. Sci. USA 82:6014, 1985) was modified to measure changes in steady-state hepatocyte volume during osmotic stress. Hepatocytes in mouse liver slices were loaded with tetramethylammonium ion (TMA$\sp{+}$) during transient exposure of cells to nystatin. Intracellular TMA$\sp{+}$ activity (a$\sp{\rm i}\sb{\rm TMA}$) was measured with TMA$\sp{+}$-sensitive, double-barreled microelectrodes. Loading hepatocytes with TMA$\sp{+}$ did not change their membrane potential (V$\sb{\rm m}$), and under steady-state conditions a$\sp{\rm i}\sb{\rm TMA}$ remained constant over 4 min in single impalements. Hyperosmotic solutions (50, 100, & 150 mM sucrose added to media) and hyposmotic solutions (sucrose in media reduced by 50 & 100 mM) increased and decreased a$\sp{\rm i}\sb{\rm TMA}$, respectively, which suggested transmembrane water movements. The regression coefficient of the ratio of control a$\sp{\rm i}\sb{\rm TMA}$/experimental a$\sp{\rm i}\sb{\rm TMA}$ versus the relative osmolality of media (experimental mOsm/control mOsm) was -0.34 $\pm$ 0.03, p $<$ 0.001, which is less than expected for a perfect osmometer. Corresponding measurements of V$\sb{\rm m}$ showed that its magnitude increased with hyposmolality and decreased with hyperosmolality. When Ba$\sp{2+}$ (2 mM) was present during hyposmotic stress of 0.66 $\times$ 286 mOsm (control), cell water volume increased by a factor of 1.44 $\pm$ 0.02 compared with that of hyposmotic stress alone, which increased cell water volume by a factor of only 1.12 $\pm$ 0.02, p $<$ 0.001. Ba$\sp{2+}$ also decreased the hyperpolarization of V$\sb{\rm m}$ due to hyposmotic stress from a factor of 1.62 $\pm$ 0.04 to 1.24 $\pm$ 0.09, p $<$ 0.01. When verapamil (50 $\mu$M) was present during hyposmotic stress of 0.69 $\times$ 292 mOsm (control), cell water volume increased by a factor of 1.42 $\pm$ 0.02 compared with that of hyposmotic stress alone, which increased cell water volume by a factor of only 1.19 $\pm$ 0.02, p $<$ 0.001. Verapamil also decreased the hyperpolarization of V$\sb{\rm m}$ due to hyposmotic stress from a factor of 1.34 $\pm$ 0.07 to 1.08 $\pm$ 0.08, p $<$ 0.05. Similar results were obtained when exposing hepatocytes to Ca$\sp{2+}$-free medium plus EGTA (5 mM). It was concluded that hepatocytes partially regulate their steady-state volume during hypo- and hyperosmotic stress. However, volume regulation during hyposmotic stress diminished along with hyperpolarization of V$\sb{\rm m}$ in the presence of the K$\sp{+}$-channel blocker, Ba$\sp{2+}$, the Ca$\sp{2+}$-channel blocker, verapamil and the Ca$\sp{2+}$-chelator, EGTA. This indicated that cell calcium and membrane potassium conductance (g$\sb{\rm K}$) were involved in hepatocyte volume regulation mechanism and that variation in V$\sb{\rm m}$ provides an intercurrent, electromotive force for hepatocyte volume regulation.

Using conventional microelectrodes, I studied the electrical basis for determining the resting V$\sb{\rm m}$ in intact EC's from hamsters. The resting V$\sb{\rm m}$ were found to be $-$40 mV for aortic EC's and $-$43 mV for vena caval EC's. The contributions of ions to the resting V$\sb{\rm m}$ of aortic EC's were compared in terms of the transference number (t$\sb{\rm ion}$). To develop a technique for in situ monitoring changes in V$\sb{\rm m}$ of postcapillary venular EC's in the hamster mesentery, a voltage-sensitive fluorescent probe, bisoxonol, was used to load the cells and the fluorescence signals were analyzed under an intravital microscope by recording the fluorescence intensity (I$\sb{\rm f}$) and processing fluorescent images of the bisoxonol-loaded cells. Calibrations were conducted by simultaneously measuring changes in V$\sb{\rm m}$ with microelectrodes and bisoxonol from aortic EC's and by varying extracellular Na$\sp{+}$ in microvessels. Both calibrations yielded the linear relationship between V$\sb{\rm m}$ and bisoxonol I$\sb{\rm f}$, showing the slope of 5.7%/mV for aortic EC's and 5.2%/mV for microvascular EC's. Altering extracellular K$\sp{+}$ to 25, 50, and 100 mM in the suffusate depolarized microvascular EC's by 5, 8, and 10 mV; whereas, the same alterations via both suffusion and perfusion induced the depolarization by 18, 30, and 42 mV, indicating that the K$\sp{+}$ conductance has an asymmetric distribution. Ba$\sp{2+}$ (1 mM) produced a depolarization by 70 mV, suggesting that the activity of K$\sp{+}$ channels dominates the resting V$\sb{\rm m}$. To correlate the bradykinin-induced increase in microvascular permeability to the changes in V$\sb{\rm m}$, the albumin flux (J$\sb{\rm A}$) was measured using TRITC-albumin along with monitoring V$\sb{\rm m}$. Bradykinin(l $\mu$M) induced a hyperpolarization of EC's by 8 mV and a biphasic increase in J$\sb{\rm A}$ from the basal level of 1.00 x 10$\sp{-6}$ to a transient peak of 9.17 x 10$\sp{-6}$ followed by a sustained level of 3.05 x 10$\sp{-6}$ cm/s. The linear correlations of net increases in both the peak and the sustained values of J$\sb{\rm A}$ to changes in V$\sb{\rm m}$ indicate that the hyperpolarization determines the peak in part and the sustained level in all. Under high K$\sp{+}$ (50 mM), bradykinin produced a repolarization from a depolarized V$\sb{\rm m}$ of -54 mV to -66 mV and a smaller increase in J$\sb{\rm A}$ from the basal level of 0.38 x 10$\sp{-6}$ to the peak of 5.51 x 10$\sp{-6}$ followed by a significantly lowered, sustained level of 1.11 x 10$\sp{-6}$ cm/s. The repolarization under high K$\sp{+}$ indicates that besides the activation of Ca$\sp{2+}$-dependent K$\sp{+}$ channels, other electrical events may be implicated. The correlation between the repolarization and the lowered value of J$\sb{\rm A}$ at the peak implies that this variation in V$\sb{\rm m}$ also mediates the bradykinin-induced increase in J$\sb{\rm A}$ under high K$\sp{+}$ condition. (Abstract shortened by UMI.)

The vascular endothelial cell (EC) plays an important role in regulating vascular tone and local blood flow by sensing chemical and mechanical stimuli on the vascular wall and releasing a host of vasoactive substances upon activations of endogenous or exogenous vasoactive substances. The central hypothesis is that local control of blood now and autoregulatory behavior in the microcirculation is distinctive at different levels of the vasculature and is dependent on the cellular activities of the EC and its interaction with the local environment. The in vivo as well as the ex vivo, flow-controlled preparations of the hamster cheek pouch were utilized. Inhibition of Endothelium-Derive Relaxing Factor (EDRF) synthesis and the functional impairment by light-dye (L-D) treatment were used to remove functional characteristics of the EC. It is found that the EC played differential roles in modulating vascular tone and blood flow in distinct segments of arterioles. Impairment of the EC by L-D treatment significantly reduced both acetylcholine (Ach)-induced dilation and the local angiotensin conversion in small (4th order) arterioles (A$\sb4$). Whereas, data obtained after inhibition of EDRF synthesis indicated that EDRF pathway appeared to be the dominant regulatory mechanism mediating agonists (e.g. Ach)-induced responses in these small vessels. In large (2nd order) arterioles (A$\sb2$), on the other hand, neither L-D treatment nor EDRF inhibition affected Ach-induced dilation or local angiotensin conversion; therefore, these responses seemed to be independent of the EC or EDRF pathway. Autoregulation was observed in both A$\sb2$ and A$\sb4$ when perfusion flow (shear stress) and perfusion pressure (stretch) were elevated. Nevertheless, the underlying regulatory mechanisms in response to mechanical stimuli differed in these series-arranged arterioles. The EC/EDRF-dependent, flow-induced dilation was dominant in A$\sb2$; whereas, the myogenic autoregulation (which appears to be independent of the EC) played major role in A$\sb4$. Therefore, the function of the EC does not appear homogenous throughout the arteriolar portion of the microcirculation. Thus, the local control of blood flow and autoregulatory behavior in the microcirculation is distinctive at different levels of the vasculature; whereas, the differential role of the EC in discrete segments of series-arranged arterioles seems to be the determinant for these differences. These differential modulations of vascular tone and blood flow by the EC at discrete levels of the microcirculation may have important implications in pathological conditions, such as hypertension, diabetes, and atherosclerosis.

A stable intracellular ionic environment is necessary for hepatocytes to function normally. Thus, during hypotonic shock or L-alanine uptake, hepatocytes swell and then exhibit a regulatory volume decrease (RVD), which comprises an increase in K$\sp+$ conductance (G$\sb{\rm K}$), an increased K$\sp+$ efflux, and a hyperpolarization of transmembrane potential (V$\sb{\rm m}$). Since hepatocyte intracellular Cl$\sp-$ has been demonstrated to distribute passively with V$\sb{\rm m}$, this study is designed to test the hypothesis that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V$\sb{\rm m}$ might provide an electromotive force for the efflux of hepatocyte intracellular Cl$\sp-$, which in turn would contribute osmotically to the RVD in hepatocytes. Double-barreled ion-selective microelectrodes were used to measure the changes of hepatocyte transmembrane potential, intracellular ionic activities (especially intracellular Cl$\sp-$ activity, (a$\sp{\rm i}\sb{\rm Cl}$)), and intracellular water volume during either anisotonic stress or L-alanine uptake. Hepatocyte V$\sb{\rm m}$ hyperpolarized, (a$\sp{\rm i}\sb{\rm Cl}$) decreased, intracellular K$\sp+$ activity (a$\sp{\rm i}\sb{\rm K}$) decreased, and intracellular water volume increased during hyposmotic stress. When perfused with L-alanine, hepatocyte V$\sb{\rm m}$ exhibited a transient depolarization followed by repolarization and then underwent a constant hyperpolarization. Meanwhile, hepatocyte intracellular Na$\sp+$ activity (a$\sp{\rm i}\sb{\rm Na}$) increased, a$\sp{\rm i}\sb{\rm K}$ & a$\sp{\rm i}\sb{\rm Cl}$ decreased, and intracellular water volume increased. In both hypotonic shock and L-alanine uptake conditions, the decreased a$\sp{\rm i}\sb{\rm K}$ could be attributed to cell swelling. However, the decrease in a$\sp{\rm i}\sb{\rm Cl}$ was greater than could be accounted for by cell swelling. When the change of V$\sb{\rm m}$ was inhibited by K$\sp+$ channel blockers, the change of a$\sp{\rm i}\sb{\rm Cl}$ was also inhibited. Based on the measured a$\sp{\rm i}\sb{\rm Cl}$, Cl$\sp-$ was always at its electrochemical equilibrium in all of the control and experimental conditions. The conclusions of this study emphasize the passive distribution of hepatocyte intracellular Cl$\sp-$ with the changes of V$\sb{\rm m}$ induced by hypotonic stress and L-alanine uptake. Thus, the data strongly support the idea that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V$\sb{\rm m}$ provides electromotive force for the efflux of hepatocyte intracellular Cl$\sp-$. This could contribute to hepatocyte volume regulation during both hypotonic shock and organic solute transport.

Although tachykinins have potent vascular actions, their effect on renal resistance blood vessels is currently unknown. The vasoactive properties of tachykinins and related analogs were assessed in isolated perfused rat kidney. At a basal perfusion pressure (PP) of 75 $\pm$ 6 mm Hg (n = 5), bolus injections of substance P (SP) had no significant vasoactive effect. Following a sustained increase in baseline PP (134 $\pm$ 10 mm Hg) produced by phenylephrine (1 $\mu$M), SP evoked a dose-dependent increase in PP. The largest dose of SP increased PP by 60 $\pm$ 5 mm Hg. The vasoconstrictor response to SP was not blocked by phentolamine when angiotensin II was used to increase basal tone. Thus, the response to SP is not mediated by norepinephrine. Pressor responses to SP were not potentiated by peptidase inhibitors, captopril and thiorphan. SP(1-7) had no effect on PP, suggesting that the pressor response to SP is C-terminal dependent and tachykinin receptor mediated. The selective NK-1 receptor agonist, (Sar$\sp9$,Met(O$\sb2)\sp{11}\rbrack$SP, had no effect on PP. In contrast, both the selective NK-2 and NK-3 receptor agonists, GR-64349 and (MePhe$\sp7$) NKB, produced dose-dependent pressor responses (116 $\pm$ 8 and 134 $\pm$ 15 mm Hg increases in PP at 33 nmol, respectively) and were more potent than SP. Infusion of capsaicin (500 nM) produced an initial increase in PP following by a more prolonged decrease in PP. Clamping the renal vein produced a marked increase in PP. The localization of NK-3 receptors in rat kidney evaluated by film autoradiography using $\sp{125}$I- (MePhe$\sp7\rbrack$NKB revealed a high density of specific binding sites on the proximal ureter and renal pelvis, moderate density in the renal vein and its large branches, and a low density in the inner strip of outer medulla, but no specific binding on the renal artery system and cortex. High resolution autoradiograms demonstrated $\sp{125}$I- (MePhe$\sp7\rbrack$NKB binding sites on the tunica media of the renal vein and tunica muscularises of renal pelvis and ureter. Specific binding of $\sp{125}$I-BHSP was found in association with the renal artery and renal pelvis. No specific SP binding sites were associated with renal vein. These data indicate that the pressor effect of tachykinins in the isolated rat kidney can be mediated by NK-2 and/or NK-3 receptors. The latter may be on the vascular smooth muscle of the renal vein.

There has been heightened interest in the biology of striped bass (Morone saxatilis) because of increased pollution in their native spawning grounds and because of their extensive use in landlocked sport fisheries. Their euryhalinity makes them an excellent species for osmoregulation studies. The objective of this research was to study the rate of adaptation of striped bass gills to sea water (3% salt) after direct transfer from freshwater using biochemical (ion transport enzyme levels), physiological (chloride efflux), and ultrastructural methods. Striped bass have specialized osmoregulatory cells located on the interlamellar and afferent surfaces of their gill filaments as shown by light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). SEM studies show that apical pit (opening of one or more chloride cells) morphology changes during sea water adaptation, and the number of apical pits increases by 32.5% after two weeks in sea water. Chloride cell size and number, extent of basolateral tubular system, and number of mitochondria per chloride cell appear to increase upon adaptation to sea water. Sodium-potassium adenosine triphosphatase (Na,K-ATPase) activity is maximal on day 3 after transfer to sea water. Studies suggest that cortisol may act as a hormonal mediator for long term adaptation to sea water. The general morphology of both freshwater and sea water adapted fish gills were studied. Preliminary studies indicate that the osmium-dimethylsulfoxide-osmium method can be used to investigate intracellular structural changes in striped bass gills. Since the chloride cells are associated with the afferent surface of the filament, the blood supply to that area is also of great interest in osmoregulation studies. Studies of the gill vasculature using corrosion casting (i.e. filling blood vessels with plastic resins) and SEM indicate that the blood vessel distribution in the striped bass gill is similar to that of other euryhaline species with arterio-arterial, arterio-venous, and nutritive pathways. Blood flow may be controlled at a variety of places by sphincters, shunts and cellular contraction. Correlation of these biochemical, physiological and anatomical measurements will aid in the understanding of the process of adaptation to sea water. (Abstract shortened with permission of author.)