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J A Wood

Publications and source records attributed to J A Wood.

At least 19 recordsLinked to original sources
PubMed1992

Renal filtration, reabsorption and excretion of aluminium in the rat.

1. Plasma and urinary aluminium levels, and renal function, were investigated in a control group of rats (n = 5) and in two groups that received an intravenous bolus dose of aluminium chloride (either 25 micrograms or 800 micrograms of aluminium, n = 7 and 5, respectively). 2. In the control group (plasma aluminium concentration 76.8 +/- 14.2 ng/ml), 59.4 +/- 3.5% of the plasma aluminium was ultrafilterable. The percentage ultrafilterable after the administration of 25 micrograms of aluminium was 41.9 +/- 7.8 (plasma concentration 154.3 +/- 18.6 ng/ml). However, after administration of 800 micrograms of aluminium, to give a plasma concentration of 19,800 +/- 2956 ng/ml, only 1.06 +/- 0.13% was ultrafilterable. 3. Such results have generally been interpreted as indicating an increase in protein-binding of aluminium with increasing aluminium concentration. In buffered aqueous solutions of aluminium chloride at pH 7.4, with an aluminium concentration of 189 +/- 6 ng/ml, 96.12 +/- 0.02% was ultrafilterable (n = 6). This concentration is comparable with that attained in the low-dose (25 micrograms) aluminium group of animals and suggests that the difference between the ultrafilterable percentage of aluminium in plasma compared with that in aqueous solution is indeed due to the binding of aluminium to high Mr material (proteins). In contrast, however, in an aqueous buffered (pH 7.4) solution containing 28,200 ng of aluminium/ml, only 1.05 +/- 0.09% was ultrafilterable. This indicates insolubility (i.e. colloid formation) of the aluminium at this high concentration. The same percentage (1.06 +/- 0.13) was ultrafilterable from plasma from the high-dose (800 micrograms) aluminium group with a plasma aluminium concentration of 19,800 +/- 2956 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1992

Effect of citrate on plasma aluminium concentration and aluminium excretion in the rat.

1. Plasma aluminium concentration and urinary aluminium excretion were monitored for 4.5 h in rats after the administration of 25 micrograms or 800 micrograms of aluminium as an intravenous bolus, either as aluminium chloride or as aluminium citrate (i.e. aluminium chloride together with sodium citrate). 2. Immediately after the bolus aluminium administration, the plasma aluminium concentration was higher in the groups given aluminium chloride than in those which received aluminium citrate, although the difference was significant (P < 0.05) only for the 25 micrograms dose. This difference between aluminium chloride and citrate indicates that the citrate form has a higher volume of distribution (i.e. is able to leave the plasma). The calculated volume of distribution for the 25 micrograms of aluminium chloride (17.5 ml) was similar to the plasma volume of the rats used (15 ml). 3. In experiments in vitro, the ultrafilterability of aqueous solutions of aluminium chloride and aluminium citrate were compared. Only 1.05 +/- 0.09% of the aluminium chloride solution was ultrafilterable (aluminium concentration 28,200 +/- 730 ng/ml), whereas 97.3 +/- 2.4% of the aluminium citrate was ultrafilterable (aluminium concentration 42,000 +/- 370 ng/ml). When the filterability of aluminium in plasma was examined, the aluminium chloride ultrafilterability was identical with that in aqueous solution (1.06 +/- 0.13%, aluminium concentration 19,800 +/- 2956 ng/ml), but the aluminium citrate was 79.8 +/- 7.1% ultrafilterable (aluminium concentration 10,125 +/- 591 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1989

Long-term survival after postinfarction bypass operation: early versus late operation.

A study of 832 patients operated on within 30 days of infarction from 1974 to 1987 has resulted in 2,388 patient-years (maximum, 14 years) of prospectively acquired follow-up. This study excludes 74 patients in whom cardiogenic shock was the indication for operation. Five-year survival (+/- standard error) was 84% +/- 2%, 85% +/- 1%, and 90% +/- 1%, and 10-year survival was 71% +/- 4%, 68% +/- 1%, and 78% +/- 1% for patients with acute infarction, remote infarction, and no previous infarction, respectively. Age and left ventricular end-diastolic pressure significantly affected long-term survival for patients with acute infarction by both univariate and multivariate analysis. For patients aged less than 65 years, the 5-year and 10-year actuarial survival rates were 89% +/- 2% and 80% +/- 4%, compared with 75% +/- 3% and 58% +/- 9%, respectively, for patients aged more than 65 years. The survival percentages were 89% +/- 2% and 75% +/- 6% for patients with left ventricular end-diastolic pressure less than 15 mm Hg compared with 77% +/- 5% and 67% +/- 7% for patients with left ventricular end-diastolic pressure greater than 15 mm Hg. Operative mortality was 7.6% for patients operated on within 24 hours, compared with 4.1% for patients operated on between 2 and 30 days after infarction. Ten-year survival was similar (about 70%) for all timing groups. Based on these long-term results, there appears to be little to gain by delaying coronary artery bypass grafting, when indicated, after infarction occurs.

Adult↗
PubMed1989

Vasopressin-induced natriuresis in the conscious rat: role of blood pressure, renal prostaglandin synthesis and the peptide ANF.

1. The response to arginine vasopressin (AVP) at doses of 5 and 10 pmol (100 g body weight)-1 h-1 was studied in conscious rats during the infusion of 1% (w/v) dextrose at 11.6 ml h-1 with and without pre-treatment with indomethacin. 2. In the absence of indomethacin AVP infusion induced dose-related increases in sodium output that were positively correlated with increases in mean arterial blood pressure (MAP) and plasma atrial natriuretic factor (ANF) immunoreactivity. Increases in renal prostaglandin E2 (PGE2) synthesis were also associated with AVP infusion. 3. Indomethacin pre-treatment abolished the AVP-induced increases in renal PGE2 synthesis and also the dose-related differences in ANF immunoreactivity. Increases in MAP and sodium output were unaffected at the 10 pmol (100 g body weight)-1 h-1 dose of AVP and only slightly attenuated for the 5 pmol (100 g body weight)-1 h-1 dose. 4. For both series AVP induced marked falls in glomerular filtration rate (GFR) but only small transient falls in effective renal plasma flow. The observed falls in GFR support the view that the natriuresis is due to changes in tubular handling and not in the filtered load of sodium. 5. It is concluded that the natriuresis elicited by AVP is closely related to the pressor action of the hormone but renal PGE2 synthesis and plasma ANF are not responsible for mediating this response.

Animals↗
PubMed1989

Control of shunt pathway perfusion in diffuse granulomatous lung disease.

To assess the roles of cyclooxygenase inhibition and alveolar hypoxia in controlling the distribution of pulmonary perfusion in granulomatous lung injury, we studied 15 dogs (anesthetized and ventilated) 4 wk after intravenous injection of complete Freund's adjuvant (0.5-0.75 ml/kg). Base-line hemodynamic and blood gas observations were obtained at fractional O2 concentration (FIO2) 0.21 and 0.10. Observations at each FIO2 were repeated 30 min after infusion of meclofenemate (2 mg/kg; n = 10) or saline (n = 5). Resistance to pulmonary blood flow was assessed using the difference between pulmonary arterial diastolic and left atrial pressures (PDG). Distribution of blood flow between normal and diseased regions of the lung was evaluated with measurement of inert gas shunt flow. Before infusion, there were no significant differences between the two groups at either FIO2. At FIO2 0.10 PDG rose from 3 +/- 1 to 7 +/- 3 mmHg in the saline group and from 3 +/- 1 to 8 +/- 3 mmHg in the meclofenemate group, although the shunt flow increased from 8.7 +/- 7.7 to 12.2 +/- 9.2% and from 10.7 +/- 11.0 to 17.6 +/- 18.3 in the two groups, respectively. Saline induced no significant changes at either FIO2. After meclofenemate, PDG at FIO2 0.21 rose to 7 +/- 4 mmHg (P less than 0.015) while shunt flow fell to 5.2 +/- 6.2% (P less than 0.0125), whereas at FIO2 0.10 PDG rose to 15 +/- 5 mmHg (P less than 0.001) while shunt flow rose only to 14.3 +/- 16.4% (P = NS). We propose that perivascular inflammation enhanced perfusion of abnormal lung by elaborating vasodilator prostanoids. By inhibiting prostanoid biosynthesis, meclofenemate selectively increased resistance in diseased lung at FIO2 0.21 and lowered shunt flow. The persistent rise in shunt during hypoxia after meclofenemate suggests that factors other than prostanoids may account for the apparent attenuation of hypoxic vasoconstriction in diseased lung.

Animals↗
PubMed1986

Changes in salbutamol concentration in the reservoir solution of a jet nebulizer.

An increase in concentration of salt in the reservoir solution of jet nebulizers driven by dry compressed gas has been observed but changes in salbutamol concentration have not been investigated; therefore: Concentration changes were observed following 10 minutes nebulization for two driving sources and starting volumes. Using an electric compressor, the time courses of changes in drug concentration and output were observed for a 5 mg dose of salbutamol in 2 and 4 ml starting volumes. Changes in drug concentration were smaller for a 4 ml starting volume and for compressor driven nebulizers. Salbutamol concentration increased with the length of nebulization and the rate of increase was inversely related to starting volume. There was poor agreement between fluid and drug output for the 2 ml starting volume and drug output did not increase significantly when nebulization exceeded 4 minutes. For the 4 ml fill there was closer agreement between fluid and drug output and drug output exceeded that for the 2 ml fill after 10 minutes. In conclusion, fluid output alone is an inadequate measure of drug output and changes in drug concentration cannot be overlooked when assessing nebulizers for nebulizer therapy.

Aerosols↗
PubMed1986

Change in plasma immunoreactive atrial natriuretic peptide during sequential ultrafiltration and haemodialysis.

Plasma immunoreactive human atrial natriuretic peptide (Ir-ANP) levels were measured in eight patients with chronic renal failure who were volume-expanded and during treatment by sequential ultrafiltration and haemodialysis. One patient was studied at two separate treatment sessions. Plasma Ir-ANP levels were raised in all patients (mean +/- SE 184 +/- 44 pmol/l, n = 9) compared with healthy controls (11 +/- 1.4 pmol/l), but showed considerable inter-patient variability. Plasma Ir-ANP levels fell with fluid removal during ultrafiltration (123 +/- 30 pmol/l, n = 9, P less than 0.02) and again as fluid was removed during haemodialysis (76 +/- 20 pmol/l, n = 9, P less than 0.02). Seven patients studied 48 h later, before their next dialysis treatment, had regained weight and showed a coincident rise in circulating plasma Ir-ANP (130 +/- 33 pmol/l, n = 7). Our data would support the hypothesis that the secretion of ANP is determined by volume or by a stimulus related to volume. However, it does not exclude the possibility that a factor other than extracellular fluid volume expansion contributes to the raised plasma Ir-ANP levels in chronic renal failure.

Adult↗
PubMed1978

Pulmonary embolectomy.

Embolectomy was carried out in eight patients with pulmonary emboli. Angiographic diagnosis was obtained in six, and in two cases pulmonary angiography could not be done because of the very critical condition of the patients. In the latter two, diagnosis was made based only on clinical findings. Two patients died in the operating room (25 percent). Six patients were discharged in good condition. It is emphasized that pulmonary embolectomy should be done in cases of pulmonary emboli when a clinical status of shock is present (systolic blood pressure less than 80 mm of mercury and the patient in low cardiac output syndrome) and when there is no response to medical treatment regardless of the degree of obstruction in the pulmonary arterial tree.

Adult↗
PubMed1977

The influence of heart rate on pulmonary arterial-left ventricular pressure relationships at end-diastole.

Increased resistance to blood flow stemming from structural and functional abnormalities of the lungs may cause pressure in the pulmonary artery to exceed that in the left ventricle at the end of ventricular diastole. This study explores the possible contribution of heart rate to the diastolic pressure gradient observed in the presence of acutely induced hypoxia. Pulmonary hemodynamics were examined in mongrel dogs with chronic atrioventricular dissociation with and without hypoxia at two different heart rates and during sequential increments in heart rate while the animals breathed room air. Studies during sequential pacing indicate that heart rate was of greater importance than blood flow in determining the magnitude of the gradient. Heart rate has to be considered when the causes of pulmonary hypertension and the effects of drugs or other agents on the pulmonary circulation are being investigated.

Animals↗
PubMed1975

Late complications of aortic valve replacement with cloth-covered, composite-seat prostheses. A six-year appraisal.

Advanced actuarial techniques are used to analyze early and late results in a closely followed series of 396 patients who received a cloth-covered, composite-seat aortic prosthesis. Late mortality and various complications are carefully assessed, and most late deaths are seen to be unrelated to the prosthesis. One hundred sixteen patients with Model 2310-2320 prostheses who received warfarin postoperatively had no thromboembolic complications in 360 patient-years of follow-up (average, 3.1 years per patient); 134 patients who had the same prosthesis but did not receive warfarin had 9 emboli per 100 patient-years (average follow-up, 1.7 years per patient; total, 228 patient-years). By comparison, in 9 years' experience with non-cloth-covered Model 1200-1260 valves, 132 patients had 4.0 emboli per 100 patient-years (average follow-up, 5.1 years; total, 673 patient-years). The safety of cloth-covered valves is clearly enhanced by concomitant use of anticoagulants; the possibility that antiplatelet drugs may suffice has not yet been demonstrated. Strut cloth wear was found at reoperation in 10 patients. The Model 2400 composite strut ("track") valve with a narrow metal track on the inner surface of each strut prevents this complication.

Adolescent↗
PubMed1975

Successful use of intra-aortic balloon counterpulsation in the treatment of refractory intraoperative cardiogenic shock.

Intra-aortic balloon counterpulsation (IABC) has been used successfully in the treatment of shock following myocardial infarction. This report describes eight patients who developed medically refractory cardiogenic shock following cessation of cardiopulmonary bypass and who were treated with IABC. None of the eight became balloon dependent and seven of eight (87.5%) left the hospital doing well. The treatment of refractory intra-operative cardiogenic shock represents a new and additional indication for IABC.

Aortic Valve Stenosis↗
PubMed1972

Time course of changes in renal tissue and urinary composition after cessation of constant infusion of lysine vasopressin in the conscious, hydrated rat.

1. The changes in urinary and renal tissue composition in conscious rats were determined for up to 2 hr following the cessation of intravenous infusion of lysine vasopressin, LVP (at 60 muu./min. 100 g body wt. for 4(1/2) hr). A constant water load (4% body wt.) was maintained during and after lysine vasopressin infusion, by quantitative replacement of excreted water. In these circumstances, any changes in urinary and renal tissue composition are presumed to represent direct consequences of the rapid plasma and tissue clearance of lysine vasopressin.2. Urinary flow increased and osmolality decreased, rapidly, reaching stable values characteristic of sustained water diuresis after about 60 min.3. The steepness of the corticomedullary solute concentration gradients also decreased rapidly. Papillary Na and urea concentrations fell to values characteristic of sustained water diuresis in about 45 min.4. The changes in medullary composition were compounded of a moderate significant increase in water content, a moderate, significant decrease in Na content, and a profound decrease in urea content.5. In the eventual steady-state water diuresis, urinary outputs of Na and K were significantly lower, and of NH(4) significantly higher, than those observed in control experiments where LVP infusion was continued for the corresponding 2 hr.6. It is concluded that the diuresis following the cessation of LVP infusion is due not merely to reduced nephron permeability to water but also to a rapid reduction in the osmotic force responsible for water reabsorption from the collecting duct.

Animals↗