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Enhanced hemodynamics via geometric alteration is believed to play a role in the favorable redistribution of intimal hyperplasia (IH) in infragenicular supplementary vein cuffs. We aimed to elucidate the consequence of altering geometric configuration in anastomotic hemodynamics in cuff models. A well-validated numerical scheme was used to simulate pulsatile flows in three cuffed anastomotic models with length-to-height ratio (LHR) of 1.4, 2.2 and 3.2, and a St. Mary's boot with LHR of 2.2 at a mean flow rate of 130 mL/min. Characteristic flow patterns and wall shear stress (WSS) distributions were compared. A cohesive vortex is only present in the cuff of LHR = 1.4 and in the boot. The vortex in the cuffs becomes increasingly disorganized with increasing cuff LHR. The area of flow separation at the graft toe, prominent in the cuff of LHR = 3.2, is significantly reduced in the cuff of LHR = 1.4 and eliminated in the boot. All cuffs are characterized by flow separation, flow reversal and a sharp drop in WSS immediately distal to the cuff toe, phenomena not observed in the boot. The cuff configuration, specifically the LHR, is critical in controlling local hemodynamics. A large LHR could lead to reduced cuff performance. The study suggests the benefits of geometric optimization for reconstruction of cuffed anatomoses.

There are four themes in this teaching exercise for Professor McCance. The first challenge was to explain how a premature infant with Bartter's syndrome could survive despite having such a severe degree of renal salt wasting. Second, the medical team wanted to know why there was such a dramatic decrease in the natriuresis in response to therapy, despite the presence of a permanent molecular defect that affected the loop of Henle. Third, Professor McCance was asked why this patient seemed to have a second rare disease, AQP2 deficiency type of nephrogenic diabetes insipidus. The fourth challenge was to develop a diagnostic test to help the parents of this baby titrate the dose of indomethacin to ensure an effective dose while minimizing the likelihood of developing nephrotoxicity. The missing links in this interesting story emerge during a discussion between the medical team and its mentor.

This study was carried out to develop a two-layered finite element model of the oesophagus. The outer muscle and inner mucosal layer were constructed individually with different mechanical properties and zero-stress opening angles. With the model, two simulations were performed. First, the distention of oesophageal wall under the pressurized state was investigated, from which the effects of residual strains on the stress distribution were evaluated. Second, the buckling modes were determined using a linear eigenvalue analysis. The self-contact capability in ABAQUS was applied to simulate the folding of mucosa under the muscle contraction. The first simulation indicated that, by taking the residual strains into account, the mucosa undertook a very small portion of stress and the luminal pressure almost transmitted completely to the outer muscle layer. On the other hand, the folding of mucosa was shown to be able to reduce the contractile force of circular muscle to maintain the lumen closure. In conclusion, the preliminary study demonstrated the feasibility of simulating the oesophageal peristaltic transport using finite element analysis.

The mucosal folding is a phenomenon observed for some biological tissues, including the pulmonary airway and gastrointestinal tract. In order to understand the mechanism of the formation of mucosal folding, a thick-walled two-layered cylindrical mathematical model was developed to investigate the buckling behavior under the external pressure and circular outer boundary condition. With the finite element method, the validity and accuracy of the proposed model was verified. The results showed that the fold number was in the range of 4-6, which was agreed with the experimental observation for the mucosal folding of a porcine esophagus. The fold number was found to decrease with the increase in the ratio of the inner to outer material stiffness. The increase in the thickness of inner layer also caused a slight declination of the fold number. Since the effects of both the material and geometrical nonlinearities have been accounted for, this model is more general to be used for the prediction of the buckling behavior of the layered structure with a wide range of thickness ratios and/or stiffness ratios.

The time-dependent mechanical properties of porcine esophagus were investigated experimentally and theoretically. It was hypothesized that the viscoelasticity was quasi-linear. The incremental stress-relaxation test was conducted to identify the material constants included in the quasi-linear viscoelastic (QLV) model. To verify the predictive ability of the model, the incremental cyclic test was performed. Hysteresis was calculated and compared with that predicted by the model. Results showed that stresses relaxed by 20–30% within the first 10 s and stabilized at 50% at 300 s. The QLV model was shown to be able to describe the viscoelasticity of esophagus across various stretch levels. The model could also predict the hysteresis during cyclic test well. It suggested that the QLV could be used as the material characterization of esophageal tissue.

The aim of this paper is to study the effects of a periodically, excited wall on the oscillatory nature of wall shear stress (WSS) and flow structures. A non-Newtonian incompressible Navier–Stokes (N–S) solver with moving boundary was developed using Fasttalk language within the Fastflo environment. It was based on the methods of operator splitting and artificial compressibility with consideration to retain space conservation property. A two-dimensional channel having a dimension of a human femoral artery but with arbitrarily assigned wall movement was employed. The Newtonian version of the code was validated against published work by simulation of flow in this channel with time-varying upper and lower walls. Non-Newtonian models (approximately 45% haematocrit) of blood flow were performed for comparison. The code was then applied to a channel with a fixed, straight, upper wall and a moving indenting lower wall. Flow separation, stagnation, and unsteadiness were characteristic flow features observed in this study. The Power Law model showed higher shear-thinning effect at any time the frame produced the smallest vortices. The Casson model produced the highest WSS which was oscillatory in nature. When the upper wall was fixed, the indenting wall experienced almost twice as much as an induced oscillatory WSS as the rigid wall. The result also suggested that periodic wall movement is a mechanism of producing oscillatory WSS. This study may provide probable insights on atherogenesis, while the solution scheme may be useful in vascular biology. Copyright © 2002 John Wiley & Sons, Ltd.

Atrial natriuretic peptide (ANP) is thought to play a role in renal regulation of salt balance by reducing tubular reabsorption of sodium and chloride. Therefore, in the chronic absence of this hormone, a defect of salt excretion should be evident. We used an ANP gene deletion model to test this premise. F2 homozygous mutant mice (-/-) and their wild-type littermates (+/+) were fed an 8% NaCl diet prior to an acute infusion of isotonic saline. Arterial blood pressures, renal excretions of salt and water, as well as collecting duct transport of fluid and electrolytes were measured. Pressures were significantly higher in -/- compared with +/+ mice (139 ± 4 vs. 101 ± 2 mmHg; 1 mmHg = 133.3 Pa). There was no difference in glomerular filtration rate (-/- = 0.84 ± 0.06; +/+ = 0.81 ± 0.04 mL·min-1·g-1 kidney weight). In the collecting duct, sodium and chloride reabsorptions were significantly higher in the -/- group than in the +/+ group. As a result, natriuresis and chloruresis were relatively reduced (UNaV: -/- = 8.6 ± 1.1; +/+ = 14.0 ± 1.1; UClV: -/- = 10.1 ± 1.4; +/+ = 16.0 ± 1.1 µmol·min-1·g-1 kidney weight). We conclude that the absence of endogenous ANP activity in mice on a high-salt diet subjected to acute saline infusion causes inappropriately high reabsorption of sodium and chloride in the medullary collecting duct, resulting in a relative defect in renal excretory capacity for salt.Key words: high-salt diet; water, sodium, chloride, and potassium transport.

An integrated computer aided design/computer aided manufacture system has been used to model the complex geometry of blood vessel anastomoses. Computer models are first constructed with key dimensions derived from radiological images of bypass grafts, and from casts of actual blood vessel anastomoses. Physical models are then fabricated in one of two ways: the surface geometry data can be used to control the movement of a three-axis milling machine; alternatively, the same data can be exported in a form that can be interpreted by a stereolithography apparatus. Both methods produce geometrically defined solid investments that can be used in a multistep casting process that yields high-quality physical models for vascular fluid dynamic studies. This technique is useful for parametric studies.

The effect of altering the volumes of different body fluid compartments on the renal response to atrial natriuretic peptide (ANP) was studied in anesthetized rats before and during administration of the peptide at 170 ng/min. Four different groups were used. In the first (De), reduction of total body water content was induced by 48 h water deprivation. In the second (De+NaCl), an acute intravenous infusion after the same 48 h dehydration was used to restore the extracellular, but not the intracellular, fluid compartment. In the third (Eu+NaCl), euvolemic rats were infused with isotonic saline at the same rate as in group De+NaCl to expand both intravascular and interstitial components of extracellular fluid. In the fourth group (Eu+BSA) an infusion of hyperoncotic (6%) bovine serum albumin in isotonic saline was used to expand the intravascular volume while contracting the interstitial volume. Excretion of water and salt was predictably reduced in the De group compared with the others. This reduction was associated with increased tubular reabsorption, both upstream from the medullary collecting duct and in the duct itself. Administration of ANP did not significantly affect diuresis and saluresis, or tubular transport. By contrast, there were marked and similar diuretic and natriuretic responses to ANP in groups De+NaCl and Eu+NaCl, associated with transport inhibition primarily in the medullary collecting duct. Surprisingly, the rats infused with hyperoncotic solution (Eu+NaCl) also failed to show marked excretory or duct transport responses to ANP. According to the study design, the two nonresponding groups had, respectively, a decreased or a normal intracellular compartment, and a decreased or increased plasma volume. The common feature of both nonresponding groups was a decreased interstitial fluid compartment, whereas the two responding groups had normal or increased interstitial volume. We suggest, therefore, that a replete interstitial fluid compartment is essential for the renal response to ANP.Key words: water and sodium chloride excretion, collecting duct transport, plasma volume, interstitial fluid, intracellular compartment.

Atrial natriuretic peptide (ANP), a peptide hormone produced by the heart, exerts a chronic hypotensive effect. Knockout mice with a homozygous disruption of the pro-ANP gene (−/−) are incapable of producing ANP and are hypertensive relative to their wild-type (+/+) siblings. Previous studies showed that arterial blood pressure (ABP) was further increased in conscious −/− mice kept for 2 wk on 2% salt, but not in anesthetized −/− mice after 1 wk on 8% salt. To determine whether inconsistencies in observed effects of salt on ABP of −/− mice are due to duration of increased salt intake and/or the state of consciousness of the animals, we measured ABP from an exteriorized carotid catheter during and after recovery from anesthesia with ketamine-xylazine in adult +/+ and −/− mice kept on low (LS; 0.008% NaCl)- or high (HS; 8% NaCl)-salt diets for 3–4 wk. Conscious ABP ± SE (mmHg) of +/+ mice did not differ significantly on either diet (HS, 113 ± 3; LS, 110 ± 5). However, on HS diet −/− mice had significantly higher ABP (135 ± 3; P < 0.001) than both −/− (115 ± 2) and +/+ (110 ± 5) mice on LS diet. Anesthesia decreased ABP in all groups, but the genotype- and diet-related differences were preserved. Plasma renin activity (PRA, ng ANG I ⋅ ml−1 ⋅ h−1) in blood collected at termination of experiment was appropriately different on the 2 diets in +/+ mice (HS, 4.9 ± 1.9; LS, 21 ± 2.8). However, PRA failed to decrease in −/− mice on HS diet (HS, 18 ± 2.9; LS, 19 ± 3.7). Independent of genotype, concentration of endothelin-1 (ET-1, pg/mg protein) and endothelial constitutive NOS (ecNOS, density/100 μg protein) was significantly elevated in kidneys of mice fed on HS diet (ET-1 −/−, 31 ± 4.7 and +/+, 32 ± 4.1; ecNOS −/−, 160 ± 19 and +/+, 156 ± 19) compared with mice fed on LS diet (ET-1 −/−, 19 ± 1.9 and +/+, 21 ± 1.8; ecNOS −/−, 109 ± 13 and +/+, 112 ± 18). We conclude that, regardless of the state of alertness, −/− mice develop salt-sensitive hypertension after prolonged feeding on HS, in part due to their inability to reduce PRA, whereas the specific renal upregulation of ecNOS and ET-1 in response to HS intake may be an ANP-independent adaptive adjustment aimed at improving kidney function and counteracting the pressor effect of salt.

Transgenic mice overexpressing an atrial natriuretic factor (ANF) fusion gene (TTR-ANF) and their nontransgenic siblings were placed on a high- (8%) or low (< 0.008%)-salt diet for 14 days to determine whether the lifelong elevation of ANF in the transgenic animals compromised their ability to maintain fluid-electrolyte balance. Steady-state dietary intake and urinary output of sodium and chloride were not statistically different between TTR-ANF and control groups on either diet. By contrast, water intake and urine volume were markedly elevated in the TTR-ANF group on either diet. Arterial blood pressure, measured in anesthetized mice at the end of the dietary regimen, was significantly and similarly reduced in the TTR-ANF compared with control groups on either diet, although high salt intake was associated with increased pressure in both groups. Renal excretion of fluid and electrolytes was studied in the anesthetized mice before and after acute blood volume expansion. Although the absolute increase in fluid and electrolyte excretion was much greater on the high- than on the low-salt diet in both groups, TTR-ANF mice had an exaggerated response relative to controls on either diet. On the basis of these results, we conclude the following. 1) When they are stimulated, renal salt-conserving mechanisms are sufficiently powerful to overcome the expected natriuretic effects of chronic elevation of plasma ANF; however, the natriuretic potential of ANF can be expressed in the short term when the counterregulatory mechanisms are inactivated. 2) ANF exerts a chronic hypotensive effect that is independent of changes in renal salt excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Blackfoot disease (BFD) is an endemic peripheral arterial disease confined to the southwestern coast of Taiwan. The cause of the disease has been ascribed to the high-arsenic artesian well water. The purpose of this study was to examine the possible association between the long-term exposure to artesian well water and the change in microvascular circulation in the absence of peripheral arterial insufficiency. A total of 45 men living in the BFD-hyperendemic villages and another 51 age- sex- body-mass index-matched men who lived in nonendemic villages nearby were recruited into this study. All subjects were free from peripheral vascular disease (resting ankle-brachial index1.00), clinical claudication, cigarette smoking, diabetes mellitus, hypertension, ischemic heart disease, cerebral infarction and obesity. Laser Doppler flowmetry was used to measure the peripheral microcirculation on the big toes both at 36 degrees C (basal perfusion, Pb) and after a hyperthermic test at 42 degrees C (Ph). The time required to reach Ph (T), and the average rate (R) of increase from Pb to Ph measured by (Ph-Pb)/T were also calculated. Results showed that those living in the BFD-hyperendemic area had a lower Pb [32.8 +/- 6.0 perfusion units (PU) vs. 67.0 +/- 4.3 PU, p0.001], a lower Ph (193.2 +/- 13.6 vs. 231.1 +/- 6.3 PU, p0.005), a longer T (3.04 +/- 0.19 vs. 1.31 +/- 0.08 min, p0.001) and a slower rate of increase from Pb to Ph (48.0 +/- 4.8 vs. 76.2 +/- 5.4 PU/min, p0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Background: Potassium (K+) input occurs after meals or during ischemic exercise and is accompanied by a high concentration of L-lactate in plasma (PL-lactate). Methods: We examined whether infusing 100 µmol L-lactic acid/min for 15 min would lead to a fall in the arterial plasma K+ concentration (PK). We also aimed to evaluate the mechanisms involved in normal rats compared with rats with acute hyperkalemia caused by a shift of K+ from cells or a positive K+ balance. Results: There was a significant fall in PK in normal rats (0.25 mM) and a larger fall in PK in both models of acute hyperkalemia (0.6 mM) when the PL-lactate rose. The arterial PK increased by 0.8 mM (p < 0.05) 7 min after stopping this infusion despite a 2-fold rise in the concentration of insulin in arterial plasma (PInsulin). There was a significant uptake of K+ by the liver, but not by skeletal muscle. In rats pretreated with somatostatin, PInsulin was low and infusing L-lactic acid failed to lower the PK. Conclusions: A rise in the PL-lactate in portal venous blood led to a fall in the PK and insulin was permissive. Absorption of glucose by the Na+-linked glucose transporter permits enterocytes to produce enough ADP to augment aerobic glycolysis, raising the PL-lactate in the portal vein to prevent postprandial hyperkalemia.

Background/Aims: Since furosemide (FS) inhibits active Na+ reabsorption by medullary thick ascending limb (mTAL) in the renal outer medulla, it may decrease its work during periods of low O2 supply to deep in the renal outer medulla. This study was designed to demonstrate that there may be a dose of FS would reduce its metabolic work while preventing the excessive loss of magnesium (Mg2+). Mg2+ is important because the ATP needed to perform work must have bound Mg2+ to it. Methods: Rats were injected intraperitoneally with a range of doses of FS. The measured outcomes were urine flow rate and parameters of functions of the mTAL (i.e. urine and renal papillary osmolality and urinary excretion of Na+, Cl-, K+ and Mg2+, and concentrations of Mg2+ in serum). Results: The urine flow rate increased significantly starting at 2.4 mg FS/kg. The renal papillary osmolality decreased at ≥0.4 mg FS/kg, and the large detectable natriuresis started at 1.6 mg FS/kg. At this latter dose, the urinary excretion of Mg2+ rose significantly. Conclusion: In rats, the non-natriuretic dose of FS may reduce the work of the mTAL. The earliest indicator of reduced work in the mTAL appears to be a decrease in urine osmolality rather than a rise in urine flow rate. Higher doses of FS should be avoided, as they induce high rates of Mg2+ excretion, which can deplete the body of this essential electrolyte.

The effects of inhibition of bradykinin and prostaglandin on the renal and blood pressure responses to atrial natriuretic factor (ANF) were studied in anesthetized rats. Intraarterial infusion of the receptor antagonist D-Arg[Hyp3,Thi5,8,D-Phe7]bradykinin (BKA) at 14 μg/min, a rate sufficient to block the hypotensive response to 250 μg of bradykinin, did not affect the natriuresis due to injection of ANF (UNaV: control, before ANF, 393 ± 101, after ANF, 2322 ± 400 nmol/min; BKA, before ANF, 261 ± 72, after ANF, 2259 ± 390 nmol/min). In contrast, infusion of indomethacin (Indo) reduced the level of sodium excretion both before and especially after ANF administration (UNaV: Indo, before ANF, 75 ± 15, after ANF, 320 nmol/min). The effect of combining BKA with Indo was not different from the effect of Indo alone (UNaV: BKA + Indo, before ANF, 119 ± 26, after ANF, 469 ± 167 nmol/min). The bradykinin antagonist, with or without Indo, was associated with significant hypotension relative to control. Indo, both in the absence and presence of the antagonist, was associated with a progressive decrease in blood pressure compared with control. However, in each case the hypotensive responses to ANF were not different from those in the control group. We conclude that under the present experimental conditions bradykinin does not modify ANF-induced natriuresis. However, inhibition of prostaglandin synthesis by Indo is associated with renal salt retention, reducing natriuresis both before and after ANF administration.Key words: prostaglandin inhibition, D-Arg[Hyp3,Thi5,8,D-Phe7]bradykinin, atrial natriuretic factor.

Background: Metabolic syndrome (MS) and chronic kidney disease (CKD) are both strongly associated with coronary artery disease (CAD). Components of MS also cause CKD. The incremental effect of CKD on CAD prevalence in MS patients referred for stress imaging studies is unknown. Methods: From January to December 2005, consecutive subjects referred for a stress imaging study were prospectively enrolled. CAD was defined as fixed or reversible defects on nuclear imaging and as resting or stress-induced wall motion abnormalities on echocardiography. MS was defined using NCEP-ATP III criteria. CKD definition was based on calculated glomerular filtration rate. The independent effect of CKD on stress results was assessed using multiple variable logistic regression. Stepwise model selection was used for variable reduction, and areas under the receiver operating characteristic curves (ROC) were calculated. Results: Of 1,122 patients enrolled (mean age 61.4 years, 97% male), 535 (47%) had MS. Among MS patients, 156/535 (29%) had CKD while 116/587 (19%) subjects without MS had CKD. Subjects with CKD were older (p < 0.001) in subjects with and without MS. The presence of CKD affected prevalence of CAD in the non-MS group only, almost doubling it (20% vs. 38%, p < 0.001). Further, using the ordered nature of the 5 CKD stages, worsening severity of CKD had greater prevalence of CAD, in non-MS subjects only (p < 0.001). Conclusions: MS attenuates the effect of CKD on CAD prevalence, regardless of CKD severity. CKD almost doubles the prevalence of CAD in non-MS subjects. CKD severity is associated with greater CAD burden in the non-MS group.

Mass transfer is a major issue for producing, in particular, thicker tissue constructs in vitro. Without the support of internal capillary network, oxygen supply is restricted to the superficial layer and the survival of cells deep within the construct could be threatened. In this study, oxygen was postulated as the limiting factor for cellular activity in developing tissue construct and their correlation was investigated. Single- and double-flow perfusion bioreactors were custom designed to provide a controlled tangential laminar flow at a flowrate of 0.545 ml/min over the surface of the tissue construct (3.2 x 2 x 0.2 cm3 porous gelatin scaffold seeded with 2 x 106 cells/cm3 of porcine esophageal smooth muscle cells). Gelatin scaffold of similar size and cell seeding was cultured in Petri dish and served as a static culture control for comparison. At day 5, oxygen profile in-situ was measured across the thickness of tissue construct while cell distribution and total DNA were analyzed. Bioreactors produced higher cell proliferation activity compared to static culture. Under static culture, cells were observed to populate near the surface of tissue construct. While single-flow bioreactor improved cell infiltration/ migration in the scaffold, double-flow bioreactor improved further these cellular events and produced construct with more uniform cell distribution. These cell distributions appear to parallel that of oxygen distribution. In static culture, oxygen concentration dropped abruptly from the construct surface to a depth of about 1000 im where it was maintained at a constant level in the core at low cell density but rose near the bottom surface. In the single-flow bioreactor, oxygen level dropped linearly from the top to the bottom surface of construct. In the double-flow bioreactor, oxygen level began to drop at about 2.5 mm above the construct surface but it was maintained at almost a constant level throughout the whole thickness.

Atherosclerotic plaque formation due to lipid accumulation in the arterial wall is the major cause of stenotic coronary disease. To restore distal coronary blood supply and overcome restenotic events presented by bare wire stents, drug-eluting stent (DES) implantation is now commonly used to treat stenotic coronary disease. However, while its long-term outcome is still unavailable, early clinical results appear to be inconsistent. The use of computational models is believed to be important in understanding DES and to elucidate the delivery of drug and improve the efficacy of DES. The presence of plaque in the stented region is expected to affect drug pharmacokinetics related to DES. In this study, a 2-dimensional model which drug transfer was coupled with both luminal and transmural flows was presented to investigate drug deposition and distribution in the arterial wall. Paclitaxel was used as a model drug and its interaction with the binding sites in the tissue was treated as a reversible binding process. As predicted, the presence of plaque dramatically affects the local pharmacokinetics. Thick plaque absorbs more drugs and provides higher resistance to drug transfer in the arterial wall compared to thin plaque. Study on the effect of drug diffusivity in the plaque on drug deposition reveals that higher diffusion coefficient results in lower drug content in the arterial wall. Meanwhile, when drug partition coefficient in the plaque was varied within the range for paclitaxel, it showed negligible effect on drug deposition. In conclusion, the presence and property of plaque have an effect on the delivery of drugs in arterial wall and should be included in the modeling of drug delivery from a DES to improve the design of stent to achieve the best therapeutic outcome.

In April 2004, an outbreak of acute diarrheal illness occurred among the Orang Asli (aborigine) in the Cameron Highlands, Pahang State, Peninsular Malaysia, where rotavirus was later implicated as the cause. In the course of the epidemic investigation, stool samples were collected and examined for infectious agents including parasites. Soil transmitted helminthes (STH), namely Ascaris lumbricoides (25.7%), Trichuris trichiura (31.1%) and hookworm (8.1%), and intestinal protozoa, which included Giardia lamblia (17.6%), Entamoeba histolytica/E. dispar (9.4%), Blastocystis hominis (8.1%) and Cryptosporidium parvum (2.7%), were detected. Forty-four (59.5%) were infected with at least one parasite, 24 (32.4%), 12 (16.2%) and 8 (10.8%) had single, double and triple parasitic infections, respectively. STH were prevalent with infections occurring as early as in infancy. Giardia lamblia, though the most commonly found parasite in samples from symptomatic subjects, was within the normally reported rate of giardiasis among the various communities in Malaysia, and was an unlikely cause of the outbreak. However, heavy pre-existing parasitic infections could have contributed to the severity of the rotavirus diarrheal outbreak.

Background The effect of traditional risk factors on the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and stroke was rarely studied previously. We investigated such effect in Taiwanese type 2 diabetic patients. Materials and methods A total of 872 (422 men and 450 women) patients aged 63·5 (SD: 11·6) years were recruited. Among them, 92 cases (48 men and 44 women) had stroke. Polymerase chain reaction was used to classify the genotypes as II, ID and DD. Analyses were performed in separate sexes. Results The adjusted odds ratios for stroke for ID vs. II and DD vs. II were 0·837 (0·413–1·697) and 1·778 (0·596–5·300), respectively, for men; but were 1·700 (0·824–3·505) and 3·706 (1·375–9·985), respectively, for women. In models assuming recessive (DD vs. II + ID), dominant (DD + ID vs. II) and additive (II = 0, ID = 1 and DD = 2) transmission, none of the odds ratios was significant for men; but were all significant for women: 2·784 (1·137–6·818), 1·996 (1·006–3·962) and 1·877 (1·155–3·050), respectively. In models using patients without risk factors (hypertension, obesity, smoking or dyslipidaemia ) as a referent group and comparing them to patients with the risk factor and with ID/II, and with DD genotypes, all models (except for smoking) favoured an increasing trend of risk with patients having the risk factor and DD genotype at the highest risk in women. Similar trends for hypertension and dyslipidaemia were also observed in men. Conclusion Traditional risk factors play an important role in the association between the ACE genotypes and stroke. Patients with DD genotype and having traditional risk factors are at the highest risk.

The time-dependent mechanical properties of the porcine esophagus were investigated experimentally and theoretically. It was hypothesized that the viscoelasticity was quasilinear, i.e., the time and strain effects were independent. In order to verify the separability of time and strain effects, the stress-relaxation test was conducted at various strains and the data were fitted with the Fung's quasilinear viscoelastic (QLV) model. By using the material parameters obtained from the stress relaxation test, the cyclic peak stress and hysteresis were predicted. Results showed that the stress relaxed by 20-30% of the peak stress within the first 10 s and stabilized at approximately 50% at the time of 300 s. The relative stress relaxation R(2) (i.e., the difference of stress at a particular time to the final equilibrium stress normalized by the total difference of the peak and final stress) was not different significantly for various strains. It was also found that, by using the stress-time data during both the ramp and relaxation phases, the correlation between parameters was substantially reduced. The model could also predict the cyclic peak stress and hysteresis except for the underestimate of valley stress. We conclude that the QLV model could be used as the material characterization of the esophageal tissue.

The identification of a three dimensional constitutive model is useful for describing the complex mechanical behavior of a nonlinear and anisotropic biological tissue such as the esophagus. The inflation tests at the fixed axial extension of 1, 1.125, and 1.25 were conducted on the muscle and mucosa layer of a porcine esophagus separately and the pressure-radius-axial force was recorded. The experimental data were fitted with the constitutive model to obtain the structure-related parameters, including the collagen amount and fiber orientation. Results showed that a bilinear strain energy function (SEF) with four parameters could fit the inflation data at an individual extension very well while a six-parameter model had to be used to capture the inflation behaviors at all three extensions simultaneously. It was found that the collagen distribution was axial preferred in both layers and the mucosa contained more collagen, which were in agreement with the findings through a pair of uniaxial tensile test in our previous study. The model was expected to be used for the prediction of stress distribution within the esophageal wall under the physiological state and provide some useful information in the clinical studies of the esophageal diseases.

Portal venous gas is a well-established radiological finding in neonates. With the advancement in diagnostic imaging, more cases are being reported in adults. We present a 55-year-old man with radiological findings of both portal venous gas and pneumatosis intestinalis secondary to ischaemic necrotising enterocolitis, with subsequent fatality. The significance of finding portal venous gas and its possible aetiology is discussed.

This study employed particle image velocimetry (PIV) to validate a numerical model in a complementary approach to quantify hemodynamic factors in distal coronary anastomoses and to gain more insights on their relationship with anastomotic geometry. Instantaneous flow fields and wall shear stresses (WSS) were obtained from PIV measurement in a modified life-size silastic anastomosis model adapted from a conventional geometry by incorporating a smooth graft–artery transition. The results were compared with those predicted by a concurrent numerical model. The numerical method was then used to calculate cycle-averaged WSS (WSS cyc ) and spatial wall shear stress gradient (SWSSG), two critical hemodynamic factors in the pathogenesis of intimal thickening (IT), to compare the conventional and modified geometries. Excellent qualitative agreement and satisfactory quantitative agreement with averaged normalized error in WSS between 0.8% and 8.9% were achieved between the PIV experiment and numerical model. Compared to the conventional geometry, the modified geometry produces a more uniform WSS cyc distribution eliminating both high and low WSS cyc around the toe, critical in avoiding IT. Peak SWSSG on the artery floor of the modified model is less than one-half that in the conventional case, and high SWSSG at the toe is eliminated. The validated numerical model is useful for modeling unsteady coronary anastomotic flows and elucidating the significance of geometry regulated hemodynamics. The results suggest the clinical relevance of constructing smooth graft–artery transition in distal coronary anastomoses to improve their hemodynamic performance.

The esophagus, like other soft tissues, exhibits nonlinear and anisotropic mechanical properties. As a composite structure, the properties of the outer muscle and inner mucosal layer are different. It is expected that the complex mechanical properties will induce nonhomogeneous stress distributions in the wall and nonuniform tissue remodeling. Both are important factors which influence the function of mechanosensitive receptor located in various layers of the wall. Hence, the characterization of the mechanical properties is essential to understand the neuromuscular motion of the esophagus. In this study, the uniaxial tensile tests were conducted along two mutually orthogonal directions of porcine esophageal tissue to identify the directional (circumferential and axial), regional (abdominal, thoracic, and cervical), and layer (muscle and mucosa) variations of the mechanical properties. A structure-based constitutive model, which took the architectures of the tissue’s microstructures into account, was applied to describe the mechanical behavior of the esophagus. Results showed that the constitutive model successfully described the mechanical behavior and provided robust estimates of the material parameters. In conclusion, the model was demonstrated to be a good descriptor of the mechanical properties of the esophagus and it was able to facilitate the directional, layer, and regional comparisons of the mechanical properties in terms of the associated material parameters.

Epidemiological evidence shows an increasing prevalence of type 2 diabetes in Taiwan. The aim of this study was to assess the yearly incidence for this country during 1992-1996.Data obtained by telephone interviews of 93,484 diagnosed diabetic patients enrolled in Taiwan's National Health Insurance programme formed the basis of this study. A total of 36,153 incident cases of type 2 diabetes (17,097 men and 19,056 women) were identified and incidence rates calculated. The trends of obesity and parental diabetes were also evaluated.The overall 5-year incidences for men and women were 187.1 and 218.4 per 100,000 population, respectively. The trends from 1992-1996 were increased for all age groups in men and for most age groups in women. A 2.8-fold increase in incidence was observed for the youngest age group (35 years), in which the increase in incidence was higher than in the older age groups. Men showed a higher fold increase in incidence than did women (3.5 vs 2.1). Obesity at interview increased from 39.2% in 1992 to 47.6% in 1996 (p0.001) and was significant for all ages. Parental diabetes showed no yearly change when all patients were analysed together, but there was a trend towards a decrease in the youngest age group (35 years) and a trend towards an increase in the oldest age groups (/=55 years).An increasing incidence of diagnosed type 2 diabetes was observed for each sex in most age groups in Taiwan, but was most marked in the youngest age group. A parallel increase in obesity was observed with the increasing incidence of diabetes.

A transgenic mouse model in which atrial natriuretic factor (ANF) expression is targeted to the liver was used to study intrarenal adjustments to the chronically elevated hormone level. Such animals, designated TTR-ANF, are characterized by reduced arterial blood pressure but similar sodium excretion compared with nontransgenic siblings. Proximal tubular micro-puncture gave the following results: single-nephron filtration rate = 12.7 ± 1.1 vs. 15.6 ± 1.9 nL/min (TTR-ANF versus nontransgenic, ns); end-proximal tubular fluid/plasma concentration ratio of inulin = 1.93 ± 0.09 vs. 1.97 ± 0.15 (ns); fractional reabsorption of sodium = 45.5 ± 2.8 vs. 46.0 ± 3.8% (ns); fractional reabsorption of chloride = 33.6 ± 3.3 vs. 32.4 ± 4.1% (ns). These data indicate that life-long elevation of plasma ANF concentration was not associated with significant alteration in single-nephron filtration rate and proximal tubular function. We conclude that compensatory anti-natriuretic mechanisms, localized downstream from the proximal tubule, can prevent ANF natriuresis.Key words: micropuncture, single-nephron filtration rate, sodium chloride reabsorption.

We report a rare case of gastrointestinal tumor of the anus with an unusual presentation as a perianal lipoma. A 65-year-old man presented with a 2-month history of a painless perianal lump clinically resembling a perianal lipoma. Endoanal ultrasonography revealed a 3 x 3 cm2 mass in the intersphincteric plane. Following initial excision of the lesion, histological analysis revealed a stromal lesion comprising fascicles of spindle cells with a mitotic count of 4 per 50 x high power field. Immunohistochemical analysis displayed positive reactivity for CD34 with focal staining for CD117; S100, smooth muscle actin and desmin were not expressed. No evidence of local or distant metastatic disease was found on computed tomography of the abdomen and pelvis. The patient subsequently underwent abdominoperineal resection. The resected specimen contained a mural nodule measuring 0.7 cm, located 5 cm from the distal margin and 2 mm from the radial margin. Histological analysis confirmed a stromal tumor composed of spindle cells with mitoses up to 2 per 10 x high power field. The patient's recovery was uneventful and he was free of recurrence at the 1-year follow-up. Gastrointestinal stromal tumors of the anal canal are an extremely rare occurrence, and may mimic benign perianal lesions. Tumor size and mitotic count are the most important factors in prognosticating outcome. Oncologic resection and protracted follow-up must factor in their predilection for late recurrence and metastatic spread. The role of adjuvant therapy with STI571 here remains to be clearly defined.

Endogenous endophthalmitis is an inflammation of ocular tissues that can lead to deterioration of and loss of vision. Rarely, this can complicate the course of a patient with pyogenic liver abscess.Over an 18-month period, 68 patients were treated for pyogenic liver abscesses. Three patients, all of whom were male and with diabetes, were diagnosed with a Klebsiella pneumoniae liver abscess complicated by endogenous endophthalmitis. Open surgical or percutaneous drainage of the liver abscess was undertaken and the symptomology and outcome of the endophthalmitis reviewed.There was no mortality in our series. Two patients presented with simultaneous abdominal and ocular symptoms and one patient had ocular symptoms 3 days after surgical drainage of the liver abscess. Despite aggressive treatment, all patients had permanent deterioration of visual function with one patient becoming blind and requiring evisceration of the infected eye.Ocular symptoms in patients treated for pyogenic abscesses must be dealt with urgently with an ophthalmologic consultation. Increased awareness of this complication and a high index of suspicion are paramount for salvage of visual function.

Atrial natriuretic peptide (ANP) is thought to play a role in renal regulation of salt balance by reducing tubular reabsorption of sodium and chloride. Therefore, in the chronic absence of this hormone, a defect of salt excretion should be evident. We used an ANP gene deletion model to test this premise. F2 homozygous mutant mice (-/-) and their wild-type littermates (+/+) were fed an 8% NaCl diet prior to an acute infusion of isotonic saline. Arterial blood pressures, renal excretions of salt and water, as well as collecting duct transport of fluid and electrolytes were measured. Pressures were significantly higher in -/- compared with +/+ mice (139 +/- 4 vs. 101 +/- 2 mmHg; 1 mmHg = 133.3 Pa). There was no difference in glomerular filtration rate (-/- = 0.84 +/- 0.06; +/+ = 0.81 +/- 0.04 mL x min(-1) x g(-1) kidney weight). In the collecting duct, sodium and chloride reabsorptions were significantly higher in the -/- group than in the +/+ group. As a result, natriuresis and chloruresis were relatively reduced (U(Na)V: -/- = 8.6 +/- 1.1; +/+ = 14.0 +/- 1.1; U(Cl)V: -/- = 10.1 +/- 1.4; +/+ = 16.0 +/- 1.1 micromol x min(-1) x g(-1) kidney weight). We conclude that the absence of endogenous ANP activity in mice on a high-salt diet subjected to acute saline infusion causes inappropriately high reabsorption of sodium and chloride in the medullary collecting duct, resulting in a relative defect in renal excretory capacity for salt.

The effect of altering the volumes of different body fluid compartments on the renal response to atrial natriuretic peptide (ANP) was studied in anesthetized rats before and during administration of the peptide at 170 ng/min. Four different groups were used. In the first (De), reduction of total body water content was induced by 48 h water deprivation. In the second (De+NaCl), an acute intravenous infusion after the same 48 h dehydration was used to restore the extracellular, but not the intracellular, fluid compartment. In the third (Eu+NaCl), euvolemic rats were infused with isotonic saline at the same rate as in group De+NaCl to expand both intravascular and interstitial components of extracellular fluid. In the fourth group (Eu+BSA) an infusion of hyperoncotic (6%) bovine serum albumin in isotonic saline was used to expand the intravascular volume while contracting the interstitial volume. Excretion of water and salt was predictably reduced in the De group compared with the others. This reduction was associated with increased tubular reabsorption, both upstream from the medullary collecting duct and in the duct itself. Administration of ANP did not significantly affect diuresis and saluresis, or tubular transport. By contrast, there were marked and similar diuretic and natriuretic responses to ANP in groups De+NaCl and Eu+NaCl, associated with transport inhibition primarily in the medullary collecting duct. Surprisingly, the rats infused with hyperoncotic solution (Eu+NaCl) also failed to show marked excretory or duct transport responses to ANP. According to the study design, the two nonresponding groups had, respectively, a decreased or a normal intracellular compartment, and a decreased or increased plasma volume. The common feature of both nonresponding groups was a decreased interstitial fluid compartment, whereas the two responding groups had normal or increased interstitial volume. We suggest, therefore, that a replete interstitial fluid compartment is essential for the renal response to ANP.

Twenty-two displaced talar neck fractures were treated by open reduction and internal fixation. Four open fractures were operated within 8 hours and 18 closed injuries were treated at an average interval of 13.8 hours after injury. Fractures were classified according to Hawkins' classification into 14 type II, 7 type III and 1 type IV. At an average follow up of 4.4 years, 18 cases obtained excellent or good results. Result was fair in 2 cases of delayed union and 1 case of avascular necrosis. Another case of avascular necrosis developed osteoarthritis of the ankle and had poor result. The overall incidence of avascular necrosis of the body of the talus was 9%.

The design and development of a simulator for endovascular repair of abdominal aortic aneurysm (AAA) is described. The simulator consists of an interchangeable model of a human AAA based on computed tomography data and is produced by means of computer-aided design and manufacture (CAD/CAM) techniques. The model has renal, iliac, and femoral arteries, and is perfused with a temperature controlled blood–analog fluid under simulated physiological flow conditions. “Fluoroscopic imaging” is simulated by a computerized imaging system that uses visible light. A movable video camera relays images in the antero–posterior and lateral planes of the AAA to a monitor. The imaging system allows “arteriography” and “road-mapping” to be performed so as to facilitate accurate deployment of endovascular stent-grafts. The system has been used for teaching and demonstrating endovascular techniques to clinicians, as well as the evaluation of new stent-graft devices. Its successful incorporation into endovascular workshops has demonstrated its role in the training of clinicians in endovascular repair of AAA. © 1998 Biomedical Engineering Society.

Two cases of carbon monoxide poisoning involving 3 victims occurred in Cameron Highlands in the months of August and September 1995. Two of the victims were found dead in the bathrooms where they were taking a bath while the other one survived. Blood toxicology from the post mortems revealed high levels of carbon monoxide. The only significant source of carbon monoxide in both cases were the gas water heaters which were installed in the bathrooms. A multigas detector was used to monitor the level of carbon monoxide in one of the bathrooms and carbon monoxide was found to be produced to 1200 ppm in 16 minutes during operation of the heater. Carbon monoxide poisoning from gas water heaters installed in bathroom is a significant hazard.

During dietary salt deprivation, the sympathetic nervous system and the angiotensin-aldosterone system are stimulated. Both systems are thought to be essential for maximal salt conservation by the kidney. To study their relative contributions, we produced negative salt balance in rats by intraperitoneal injection of furosemide, followed by a low-salt diet (

Chronic salt depletion was used as a model to study the mechanism of renal resistance to the natriuretic effect of atrial natriuretic factor (ANF). Rats were pretreated with furosemide and placed on a low-salt diet (

Atrial natriuretic peptide (ANP)-gene knockout mice of three genotypes (+/+, +/-, and -/-) were maintained on a low-salt diet (0.008% NaCl). They were then fed either the same low-salt diet or a high-salt diet (8% NaCl) for 1 wk. No differences were found among genotypes in daily food and water intakes or in urinary volume and electrolyte excretions. Arterial blood pressures measured in anesthetized animals at the end of the dietary regimen were significantly and similarly increased in -/- compared with +/+ mice on each diet. Renal excretion of fluid and electrolytes was measured in anesthetized mice before and after acute blood volume expansion. No genotype differences were observed before volume expansion. After volume expansion the wild-type (+/+) mice had much greater saluretic responses than either the heterozygous (+/-) or the homozygous mutant (-/-) animals on the low-salt diet but not on the high-salt diet. We conclude that ANP lowers blood pressure in the absence of detected changes in renal function; ANP is not essential for normal salt balance, even on high-salt intake; and ANP is essential for the natriuretic response to acute blood volume expansion on a low-salt but not high-salt intake.

To investigate the nature of exposure factors, and effectiveness of countermeasures in head injuries in children and adolescent of Taiwan area, we conducted a retrospective study on 820 children and adolescents with head injuries consecutively admitted to Chang Gung Memorial Hospital from January 1985 to December 1989. We analyzed the data by chart review and divided the cases into four age-groups: group A (0-4 years old), group B (5-9 years old), group C (10-14 year old) and group D (15-17 years old). The boy to girl ratio was 2.43. The largest proportions of head injuries were the adolescents in group D. The most common cause of head injury was traffic accidents (74%); while the falls were contributed the main cause in other studies. In all group A, B and D, the majority of traffic accidents were pedestrian injury; while in group D, the motorcyclists or car drivers were responsible for the accidents. Fall from height was the major cause of fall in all four age-groups, but it was fall from bicycle or during play or sports in group C. Injuries were most common in summer and clustered at afternoon in all patients. Majority of head injuries occurred outdoors. Most children and adolescents suffered from mild head injury, but there were still 203 cases with severe head injury (24%). Eighty-one cases (9.9%) were either discharged in critical condition or died at the hospital. There were no significant differences in mortality among four age-groups.

To evaluate the relationship of body composition with physical activity and other anthropometric factors, a group of 437 healthy Chinese men and women were recruited. Body composition was measured using the bioelectric impedance technique. Levels of physical activity (LPA) were classified as light, moderate and heavy. Anthropometric factors evaluated included body mass index (BMI), ponderal index (PI), waist-to-hip ratio (WHR), triceps skinfold thickness (TSF), mid-arm circumference, mid-forearm circumference, arm muscle circumference (AMC) and arm muscle area (AMA). Sex was found to be highly associated with body composition, with females having a higher percentage of body fat and males having a higher percentage of body lean mass. This gender difference was independent of age, physical activity or other anthropometric factors. An increased level of physical activity was associated with higher body lean mass and lower body fat. Sex, LPA, TSF, PI and WHR were all entered into the regression equations to estimate body composition. Sex and physical activity have an independent effect on body composition and the commonly used estimators for adiposity and fat distribution such as BMI, PI, TSF and WHR are closely correlated with body composition.

1. Chronic reduction of salt intake can reduce the natriuretic effect of exogenously administered atrial natriuretic factor. The purpose of this study was to elucidate the intrarenal site(s) of such atrial natriuretic factor resistance. Renal clearance and collecting duct microcatheterization experiments were made before and during infusion of atrial natriuretic factor in three groups of rats: group 1 consisted of rats fed a high salt diet (8% NaCl) for 1 week before the experiment; group II were fed a low salt diet (< 0.008%); group III received the same low salt diet, but were acutely replenished with salt at the time of experiment. 2. Baseline sodium chloride excretion was 6480 ± 810 nmol min−1g−1 kidney weight in group 1 compared to 99 ± 16 in group 1. Fractional re-absorptions in the medullary collecting duct were 37 ± 6% and 95 ± 2% of delivered load, respectively (P < 0.05). The fractions of filtered sodium remaining at the beginning of the medullary duct were 6.6 ± 1.0% of filtered load in group 1 and 2.7 ± 0.7% in group II (P < 0.05), indicating increased tubular reabsorption in group II, not only in the medullary duct, but also in upstream nephron segments. 3. During infusion of atrial natriuretic factor, marked saluresis (13240 ± 750 nmol min−1 g−1 kidney weight), together with decreased fractional reabsorption at both sites (duct, −13 ± 9%; upstream remainder, 7.9 ± 0.7%; P < 0.05 each, compared to corresponding control values) was found in group 1, whereas the excretory (150 ± 28 nmol min−1 g−1 kidney weight), and the tubular transport (duct = 84 ± 3%; upstream remainder =2.2 ± 0.4%) changes were quantitatively insignificant in group II. Glomerular filtration rate was increased in group 1 from 1.07 ± 0.03 to 1.26 ± 0.04 ml min−1g−1 kidney weight (P < 0.05), but not in group II (0.93 ± 0.07 to 0.96 ± 0.09, not significant). 4. In group III, acute salt replenishment was associated with increased excretion (1940 ± 440 nmol mm−1 g−1 kidney weight, P < 0.05 compared to group II) and with reduction of tubular reabsorption in the collecting duct only (69 ± 8%, P < 0.05). Infusion of atrial natriuretic factor in this group further increased natriuresis (7810 ± 780 nmol min−1 g−1 kidney weight) and decreased tubular reabsorption in the duct (−32 ± 22%, P < 0.05 compared to the corresponding control value). 5. We conclude that chronic salt deprivation can effectively prevent, via a rapidly reversible counter-regulatory mechanism, the expected actions of atrial natriuretic factor on sodium reabsorption in the medullary collecting duct. Operation of such a mechanism may explain salt retention despite elevated endogenous levels of atrial natriuretic factor in pathological states such as congestive heart failure and liver cirrhosis.

The purpose of this study was to evaluate risk factors associated with peripheral vascular disease (PVD) in patients with non-insulin-dependent diabetes mellitus (NIDDM). A group of 100 patients (50 men and 50 women) aged 50 years or over with PVD and another group of 200 age-sex-matched patients (100 men and 100 women) without PVD were studied. The mean +/- standard error of ages for subjects with and without PVD were 60.8 +/- 0.6 years and 59.7 +/- 0.3 years, respectively. Doppler ultrasound was used to measure the systolic pressures of the brachial, posterior tibial and dorsal pedal arteries bilaterally. The diagnosis of PVD was made by an ankle-brachial index (ABI)0.90 and the diagnosis of non-PVD by an ABI1.00. The association of PVD with diabetic duration, body mass index (BMI), cerebral infarction (CI), coronary heart disease (CHD), proteinuria, diabetic retinopathy, neuropathy, hypertension, and cigarette smoking was evaluated. In addition, biochemical data including fasting plasma glucose, hemoglobin (HD)Alc, cholesterol, triacylglycerol, high- and low-density lipoprotein cholesterol, uric acid, blood urea nitrogen (BUN) and creatinine (Cr) were studied. In univariate analysis, PVD was associated with an increased level of systolic blood pressure (SBP), BUN and Cr, cigarette smoking, CI, CHD, proteinuria and retinopathy. In stepwise logistic regression analysis, the level of SBP, cigarette smoking and CI remained statistically significant. The log odds of PVD could be expressed as: -2.834 + 0.013 (SBP in mmHg) + 0.577 (cigarette smoking) + 1.320 (CI). PVD is the result of aggregation of atherosclerotic risk factors; among those factors noted in this study, SBP, cigarette smoking and CI are important.

In this study, we evaluated the correlation of four types of hand strength (hand grip, tip pinch, palmar pinch and key pinch) with age, sex, body weight, body height, body mass index, triceps skinfold thickness, mid-arm circumference and mid-forearm circumference in a group of 437 Chinese adults (195 men and 242 women) who ranged in age from 28 to 78 years. All of the hand strengths studied correlated positively with gender, body weight, body height, mid-arm and mid-forearm circumference and negatively with age and triceps skinfold thickness in the analyses of simple correlation coefficients. Men were found to be more powerful than women in all hand strength types in different age groups. The magnitude of strength decline with age was more prominent in grip strength than pinch strength including palmar, tip and key. Stepwise multiple regression analyses showed that sex, age and mid-forearm circumference were most predictive of all types of hand strength. Body height was an additional independent predictor of grip and palmar pinch. Body mass index, body weight, mid-arm circumference and triceps skinfold thickness were not independent predictors associated with hand strength.

Tai Chi Chuan (TCC; shadow boxing) is a traditional Chinese conditioning exercise. To evaluate its beneficial effect on cardiorespiratory function, 21 male and 20 female TCC practitioners, ranging in age from 50 to 64 years, voluntarily participated in this study. The control group comprised 23 male and 26 female sedentary subjects. Breath-by-breath measurement of the cardiorespiratory function was obtained during the incremental exercise of leg cycling. At the maximal exercise level, the oxygen uptake (VO2), O2 pulse and work rate of the TCC group were significantly higher than the respective values of the control group (p0.01). At the ventilatory threshold, the TCC group also showed a higher VO2, O2 pulse and work rate (p0.05). The results imply that TCC training may be beneficial to the cardiorespiratory function of older individuals. To estimate the exercise intensity of TCC, heart rate (HR) was monitored in 15 men and 15 women while they performed the classical Yang TCC. During the steady-state performance of TCC, the mean HR was 130 +/- 14 bpm for men and 127 +/- 13 bpm for women. The mean HR during TCC exceeded 70% of their HRmax. Our data substantiate that TCC is aerobic exercise of moderate intensity, and it may be prescribed as a suitable conditioning exercise for the elderly.

Weanling Dahl rats of the salt-sensitive and salt-resistant strains were kept either on a low salt diet for 10–15 weeks, or the diet was supplemented with 7% NaCl for the last 30 days. Animals were anesthetized and the renal responses to acute saline infusion and infusion of synthetic atrial natriuretic factor (ANF) were studied on both dietary regimens. Arterial blood pressures of sensitive and resistant groups were not different on the low salt intake. As expected, addition of dietary salt increased pressure markedly in the sensitive animals. Resistant rats also had smaller, but statistically significant, increases in pressure. On the low salt diet, salt-sensitive rats showed a larger renal response to saline infusion, whereas on the high salt diet there were no significant differences between strains. The responses to ANF infusion were not different between groups on either diet, although NaCl feeding potentiated the natriuresis and diuresis. Under the conditions of the present experiments there was, therefore, no indication that Dahl salt-sensitive rats had a relative inability to respond either to an acute saline load or to exogenous ANF administration.

Characteristics of sodium transport in the inner medullary collecting duct were determined in anesthetized rats before and during intravenous infusion of synthetic atrial natriuretic factor (atriopeptin II). Infusion of the factor was associated with increased sodium delivery and reduced fractional reabsorption in the duct. Increasing delivery to the same extent by KCl infusion had no effect on fractional reabsorption. The results demonstrate that atrial natriuretic factor has a specific inhibitory effect on net sodium transport in this part of the nephron. The mechanism of this inhibition may involve induction of sodium permeability and consequent backflux into the tubular lumen.

1. The possible involvement of renal nerves in the diuresis and natriuresis of blood volume expansion was studied in anaesthetized rats. Acute unilateral renal denervation caused increased excretion of fluid, sodium and potassium. 2. Renal blood and plasma flows were elevated without change in filtration rate. Intracortical blood flow distribution was not affected by the denervation. 3. Blood infusion caused diuresis, natriuresis and kaliuresis in both denervated and shamdenervated kidneys, associated with comparable initial increases in filtration and decreases in renal blood flow. No change in flow distribution was found, whether or not renal nerves were intact. 4. Although the magnitude of the excretory response to hypervolaemia was greater in denervated kidneys, the temporal pattern was identical with that of sham-operated kidneys. Our data thus do not show an effect of efferent renal nerve activity on volume natriuresis.