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Biomedical subjects

J E Hall

Publications and source records attributed to J E Hall.

At least 307 records · Page 17Linked to original sources
PubMed1987

Role of renal nerves in compensatory adaptation to chronic reductions in sodium intake.

The aim of this study was to investigate the importance of the renal nerves in adaptation to chronic reductions in sodium intake. Conscious dogs with unilateral (n = 7) or bilateral (n = 4) renal denervation were studied. In dogs studied before and after bilateral denervation, there were no differences in urine volume (UO), Na excretion (UNaV), or fractional reabsorption of Li (FR Li, an index of proximal tubular Na reabsorption) between innervated and denervated kidneys on either normal (80 meq/day) or low Na intake (5 meq/day, 15 days). Plasma renin activity (PRA) was attenuated following denervation on both normal (0.39 +/- 0.06 vs. 0.18 +/- 0.01 ng angiotensin I X ml-1 X h-1) and low Na intake (1.00 +/- 0.06 vs. 0.59 +/- 0.01). In unilaterally denervated dogs the left kidney was denervated and the bladder was split, allowing continuous urine collection from separate innervated and denervated kidneys in the same dog. There was no difference in UO between innervated and denervated kidneys on normal (80 meq/day) or low (7 meq/day, 9 days) Na intake. UNaV averaged 33.6 +/- 1.3 and 37.6 +/- 2.1 meq/day in innervated and denervated kidneys, respectively, on normal Na intake and 3.5 +/- 0.5 and 4.0 +/- 0.4 meq/day in innervated and denervated kidneys on low Na intake. FR Li was not different in denervated compared with innervated kidneys during normal or low sodium intake. Norepinephrine content was reduced by 99 +/- 1% in denervated kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1987

Role of the liver in renal hemodynamic response to amino acid infusion.

The purpose of this study is to determine the quantitative importance of the liver in mediating the increases in renal blood flow and glomerular filtration rate (GFR) that occur after elevation of plasma amino acids. A mixture of four amine acids (Gly, Ser, Ala, Pro at 0.075 mmol X kg-1 X min-1 total) was infused intravenously into normal anesthetized dogs and into a second group of dogs after ligating all blood vessels supplying the liver and inserting a hepatic portal-femoral venous shunt. In normal dogs, renal blood flow and GFR rose by an average of 20 +/- 3 and 15 +/- 4%, respectively, after 30 min of amino acid infusion, while renal vascular resistance fell 16% from 0.51 +/- 0.16 to 0.43 +/- 0.16 mmHg X ml-1 X min. The responses of dogs in which the hepatic circulation was ligated were not significantly different from those in normal animals; renal blood flow and GFR increased by 20 +/- 3 and 31 +/- 7%, respectively, and renal vascular resistance fell 26% from 0.80 +/- 0.13 to 0.59 +/- 0.08 mmHg X ml-1 X min after 30 min of amino acid infusion. Because ligation of the blood supply to the liver did not prevent the renal hemodynamic response to amino acid infusion, it appears that the liver does not play a major role in mediating renal vasodilation during elevation of plasma amino acids.

Amino Acids↗
PubMed1987

Vascular pressure effects on lung edema formation after glass bead embolism.

The canine lung lobe was embolized with 100-micron glass beads before lobectomy and blood anticoagulation. The lobe was isolated, ventilated, and pump-perfused with blood at an arterial pressure (Pa) of about 50 (high pressure, HP, n = 9) or 25 Torr (low pressure, LP, n = 9). Rus/PVR, the ratio of upstream (Rus) to total lobar vascular resistance (PVR), was determined by venous occlusion and the isogravimetric capillary pressure technique. The capillary filtration coefficient (Kf), an index of vascular permeability, was obtained from rate of lobe weight gain during stepwise capillary pressure (Pc) elevation. The embolized lobes became more edematous than nonembolized controls, (C, n = 11), (P less than 0.05), with Kf values of 0.20 +/- 0.04, 0.25 +/- 0.06, and 0.07 +/- 0.01 ml X min-1 X Torr-1 X 100 X g-1 in LP, HP, and C, respectively (P less than 0.05). The greater Rus/PVR in embolized lobes (P less than 0.05) protected the microvessels and, although Pc was greater in HP than in controls (P less than 0.05), Pc did not differ between HP and LP (P greater than 0.05). Although indexes of permeability did not differ between embolized groups (P greater than 0.05), HP became more edematous than LP (P less than 0.05). The greater edema in HP did not appear due to a greater imbalance of Starling forces across the microvessel wall or to vascular recruitment. At constant Pc and venous pressure, elevating Pa from 25 to 50 Torr in embolized lobes resulted in greater edema to suggest fluid filtration from precapillary vessels.

Animals↗
PubMed1987

Massive transfusion of perfluorocarbon emulsion (Fluosol-DA) in newborn piglets.

To study massive perfluorocarbon transfusion in neonatal animals, 30 piglets (less than 24 h old) were randomly assigned to 3 groups: Fluosol-DA-treated (50 ml/kg), albumin-treated (50 ml/kg), and non-treated controls. Pre- and post-transfusion measurements included blood chemistries and complete blood count (CBC). Post-transfusion histological analysis of tissues was also performed. There was no mortality or respiratory distress in the piglets that received Fluosol transfusion. Fluosol-treated piglets had significantly lower (p less than 0.05) post-transfusion serum calcium and serum glutamic oxaloacetic transaminase values than the controls. The Fluosol group also had significantly higher chloride and glucose, but lower calcium and bilirubin levels than the albumin group. However, in no cases were the differences of clinical significance. There were no differences between the experimental groups' pre- and post-transfusion CBC values. Microscopic examination of lung, heart, and spleen samples revealed only the presence of splenic vacuoles which we attributed to perfluorocarbon accumulation.

Animals↗
PubMed1987

Further biochemical characterization of chronic Trypanosoma brucei gambiense-Microtus montanus infection.

Tyrosine aminotransferase (TAT), glutamic-pyruvic transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), and alkaline phosphatase (ALP) were measured in the serum and livers of Microtus montanus infected with Trypanosoma brucei gambiense. Only liver TAT and serum ALP showed significant changes. In addition, blood glucose, pyruvate and lactate, and liver glycogen levels were assayed. All four compounds showed significant changes, strongly suggesting increased glycogen mobilization and increased catabolic activity. Interestingly, the serum ketone levels were very low and no significant changes were observed. These chronically infected animals had an organic aciduria in which pyruvate, lactate, beta-hydroxybutyrate, alpha-ketoglutarate, phenylpyruvate, and p-hydroxyphenylpyruvate were significantly increased. The possible significance of these observations is discussed.

Alkaline Phosphatase↗
PubMed1987

Amphotericin B dosage for disseminated candidiasis in premature infants.

Amphotericin B (Amp-B) serum concentrations were determined in five infants with disseminated candidiasis. All patients had positive blood cultures for Candida and one patient had Candida albicans meningitis. Amp-B sterilized the blood and the cerebrospinal fluid within four to nine days. Total doses of Amp-B varied from 11.6-62.3 mg. There was no laboratory or clinical evidence of renal toxicity. Two infants died of causes unrelated to disseminated candidiasis. Disseminated candidiasis in premature infants was treated successfully with 0.5 mg/kg doses of Amp-B, but further studies with more evaluable cases are needed to confirm the correct dose.

Amphotericin B↗
PubMed1987

Results of surgical treatment of adults with idiopathic scoliosis.

The outcome of surgical treatment of idiopathic scoliosis in forty-five adults was studied with special attention to pain, function, self-image, and pulmonary function. All of the patients were more than twenty-five years old at operation and had been followed for more than three years. Every patient who was operated on by one of us (J. E. H.) and who met these criteria was evaluated. The magnitude of the curves averaged 66 degrees. Standardized gradations of pain and function showed improvement over-all, but significant impairment remained. There was a reduction in the levels of peak and constant pain, but no change in the frequency of peak pain after operation. The number of patients who were pain-free after surgery was not increased. Functional impairment due to the scoliosis was lessened, and the ability to perform the common activities of daily living was improved, but no important changes in occupation or recreational activity were recorded. Correlations of pain or function, or both, and the changes in either, were found with only two parameters: age at follow-up and physical occupation. Pulmonary function, as measured, did not change. Eighteen (40 per cent) of the patients had a minor complication and ten (20 per cent), a major complication; there was one death, due to pulmonary embolism, of a patient who was excluded from the series. In view of the high rate of complications, the limited gains to be derived from spinal fusion should be assessed and clearly explained to patients before the procedure is undertaken.

Activities of Daily Living↗
PubMed1986

Osteoid osteoma: localization by intraoperative magnification scintigraphy.

Surgical localization of osteoid osteomas is a major problem in the diagnosis and therapy of this lesion. Visual, tactile, and radiographic localization is often equivocal and as a consequence incomplete excision of the tumor, or excessive removal of bone may result. We performed magnification intraoperative bone scintigraphy using a portable gamma camera and a radioactive pointer in six patients with osteoid osteoma. Accurate localization and complete removal of the tumor was achieved in all six with only minimal delays in the surgical procedure. The advantages of this technique and recommendations for its use are discussed.

Adolescent↗
PubMed1986

Effect of fluosol-DA infusion on pulmonary vascular permeability in the dog lung.

Oxygen-carrying perfluorocarbon (PFC) emulsions show clinical promise as blood supplements or substitutes. However, some evidence suggests that PFC emulsions may accumulate in the lungs to disrupt pulmonary function. This study was conducted to determine whether the infusion of a PFC emulsion (Fluosol-DA) would alter microvascular permeability in the isolated canine right lower lung lobe (RLL). RLL's, perfused at constant pressure with autogenous blood, were divided into three groups: Group I (n = 6), the control group, was infused with bovine serum albumin (BSA) until the BSA solution equaled 10% of the total blood volume in the perfusion system; Group II (n = 6) was infused with Fluosol-DA until the emulsion comprised 10% of the final blood volume; and Group III (n = 6) was infused with Fluosol-DA until it comprised 20% of the final blood volume. The pulmonary filtration coefficient (Kf), an index of microvascular permeability, was obtained in each group approximately 1 hour after infusion. The Kf values for the control, 10% Fluosol, and 20% Fluosol groups were 0.070 +/- 0.018, 0.127 +/- 0.024, and 0.115 +/- 0.022 ml X min-1 X mm Hg-1 X 100 gm-1, respectively, and were not significantly different (p greater than 0.05) from each other. Perfusate oncotic pressure, lobar compliance, blood gas levels, and pulmonary arterial pressure did not vary significantly among the experimental groups. Under these experimental conditions, Fluosol-DA, in blood concentrations that might be used clinically, was not associated with an increased microvascular permeability in the isolated dog lung lobe.

Animals↗
PubMed1986

The Boston bracing system for idiopathic scoliosis. Follow-up results in 295 patients.

A total of 295 patients treated with the Boston bracing system with follow-up of at least 1 year after completion of bracing are reviewed. Pre-brace curves ranged from 20-59 degrees Cobb. Mean age at brace initiation was 13.2 years with a mean treatment time of 2.9 years and mean follow-up of 1.4 years. Mean best in-brace correction averaged 50% with correction averaging 23% at the initiation of weaning from the brace. By the time of brace discontinuance, average curve correction was 15%. At follow-up, average correction was 11%. A comparison of follow-up with pre-brace values of major curves showed that 49% were unchanged +/- 5 degree, 39% achieved final correction of 5-15 degrees, 4% achieved final correction of 15 degrees or more, 4% of patients lost 5-15 degrees, and 3% lost more than 15 degrees by the time of follow-up. Eleven percent of patients underwent surgery during the period of bracing; 1% had surgery during follow-up period. Correction and control of major curves with apexes below T8 and above L2 were best. A strong correlation between best, or initial in-brace correction, and follow-up correction was noted. Young age at the initiation of bracing and higher degrees of pre-brace curvature increased the incidence of surgery. Those curves that had corrected most at the end of bracing were most at risk for loss of correction after bracing. Partial compliance with brace wear appeared as effective as full-time wear. Boston braces without superstructure appeared to be as effective as braces with superstructure for curves with apexes below T7.

Adolescent↗
PubMed1986

Control of sodium excretion by angiotensin II: intrarenal mechanisms and blood pressure regulation.

Angiotensin II (ANG II) is one of the body's most powerful regulators of Na excretion, operating through extrarenal mechanisms, such as stimulation of aldosterone secretion, as well as intrarenal mechanisms. Considerable evidence suggests that the intrarenal actions of ANG II are quantitatively more important than changes in aldosterone secretion in the normal day-to-day regulation of Na balance and arterial pressure. ANG II at physiological concentrations increases proximal tubular reabsorption, but further studies are needed to determine whether ANG II also has an important effect on more distal tubular segments. ANG II also markedly constricts efferent arterioles, tending to increase Na reabsorption by altering peritubular capillary physical forces and also helping to prevent excessive decreases in glomerular filtration rate. ANG II may also decrease Na excretion and increase urine concentrating ability by reducing renal medullary blood flow. Regulation of Na excretion by ANG II is closely linked with arterial pressure control and volume homeostasis through the renal pressure natriuresis mechanism. Under many physiological conditions, such as changes in Na intake, ANG II greatly multiplies the effectiveness of the pressure natriuresis mechanism to prevent fluctuations in body fluid volume and arterial pressure. In circumstances associated with circulatory depression, such as decreased cardiac function, reductions in blood pressure and increased ANG II formation cause Na retention until arterial pressure is restored to normal. However, in pathophysiological conditions in which ANG II is inappropriately elevated, increased arterial pressure (hypertension) is required for the kidney to "escape" the potent antinatriuretic actions of ANG II and to return Na excretion to normal via the pressure natriuresis mechanism.

Absorption↗
PubMed1986

Renal hemodynamics and arterial pressure during chronic intrarenal adenosine infusion in conscious dogs.

The major aim of this study was to examine the chronic effects of increased intrarenal adenosine (ADO) levels on control of renal hemodynamics and mean arterial pressure (MAP). In six uninephrectomized conscious dogs, intrarenal ADO infusion (2 micrograms . kg-1 . min-1) for 6 days caused no significant changes in MAP, which averaged 94 +/- 3 mmHg during the control period and 91 +/- 2 mmHg during ADO infusion. ADO infusion for 6 days decreased glomerular filtration rate (GFR) and filtration fraction while causing no significant changes in effective renal plasma flow (ERPF) or sodium and water balance. To examine the role of angiotensin II (ANG II) in altering the blood pressure and renal effects of ADO, we also studied the effects of intrarenal ADO infusion in five uninephrectomized conscious dogs during continuous intrarenal infusion of ANG II (1 ng . kg-1 . min-1) to prevent renal levels of ANG II from decreasing. However, even when renal ANG II levels were maintained constant, ADO infusion at 2 micrograms . kg-1 . min-1 for 4 days and 10 micrograms . kg-1 . min-1 for 5 days failed to alter MAP, which averaged 104 +/- 6 mmHg during the control period, 106 +/- 5 mmHg during infusion of 2 micrograms . kg-1 . min-1, and 105 +/- 5 mmHg during infusion of 10 micrograms. . kg-1 . min-1 ADO. Intrarenal ANG II infusion did not prevent decreases in GFR and filtration fraction during ADO infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1986

Renal escape from vasopressin: role of pressure diuresis.

This study was designed to examine the role of increased renal artery pressure (RAP) in mediating escape from the antidiuretic action of vasopressin (AVP). In six conscious dogs in which RAP was permitted to increase, AVP infusion, at a rate (0.2 mU X kg-1 X mm-1 iv) that was acutely subpressor, gradually raised mean arterial pressure (MAP) from 97 +/- 2 to 126 +/- 4 mmHg after 5 days while decreasing urine volume and increasing urine osmolality. However, after 4-5 days of AVP infusion, urine volume and osmolality returned to control, and the hypertensive effect of AVP waned so that after 9 days of AVP, MAP averaged only 113 +/- 5 mmHg. In contrast, when RAP was prevented from increasing in seven dogs with a servo-controlled aortic occluder, AVP caused sustained decreases in urine volume and elevated urine osmolality from 609 +/- 27 to 1,160-1,711 mosmol/kg H2O throughout 8 days of infusion. The hypertensive effect of AVP did not wane when RAP was servo-controlled, and after 8 days of AVP infusion, MAP averaged 152 +/- 7 mmHg, compared with a control of 96 +/- 2 mmHg. Servo-controlling RAP also prevented the marked sodium and chloride losses seen with chronic AVP infusion in normal dogs. These findings indicate that escape from the antidiuretic action of AVP is mediated by increased RAP, which causes diuresis and natriuresis, thereby diminishing the hypertensive effect of AVP. However, when pressure diuresis and natriuresis are prevented, AVP causes severe chronic hypertensive, suggesting that AVP could be an important hypertensive mechanism when renal function is impaired.

Animals↗
PubMed1986

Adenosine alters glomerular filtration control by angiotensin II.

This study was designed to test the hypothesis that high renal levels of adenosine (ADO) may alter glomerular filtration rate (GFR) control by angiotensin II (ANG II). In normal kidneys, ANG II infusion (20 ng X kg-1 X min-1 iv) decreased renal blood flow (RBF) to 61 +/- 3% of control, increased filtration fraction (FF) to 173 +/- 21% of control, and did not change GFR significantly. During intrarenal ADO infusion at a rate of 1.0 mumol/min, ANG II (20 ng X kg-1 X min-1 iv) decreased RBF and GFR to 61 +/- 5 and 64 +/- 6% of control, respectively. After blocking changes in tubuloglomerular feedback by occluding the ureter during mannitol diuresis, ANG II increased stop-flow pressure and postglomerular resistance (RPG) markedly but did not alter preglomerular resistance (RA), suggesting that the direct actions of circulating ANG II are confined primarily to efferent arterioles in the absence of changes in tubuloglomerular feedback. However, during intrarenal ADO infusion and inhibition of tubuloglomerular feedback, ANG II decreased stop-flow ureteral pressure and raised RA and RPG to 213 +/- 27 and 155 +/- 7% of control, respectively, while decreasing RBF to 59 +/- 5% of control. These observations suggest that ADO markedly alters the control of GFR by ANG II, possibly by causing ANG II to constrict preglomerular vessels, an effect that is not apparent in most physiological conditions but which could play a role in lowering GFR when renal ADO and ANG II levels are both elevated, as in severe renal ischemia.

Adenosine↗
PubMed1986

Mechanisms controlling renal hemodynamics and electrolyte excretion during amino acids.

Our purpose was to investigate the mechanisms by which increased plasma amino acids elevate renal blood flow (RBF) and glomerular filtration rate (GFR). Since transport of amino acids and Na+ is linked in the proximal tubule, we hypothesized that increased amino acids might stimulate proximal tubular Na+ reabsorption (PRNa) and thus increase RBF and GFR by a macula densa feedback mechanism. A solution of four amino acids (Ala, Ser, Gly, Pro) was infused intravenously (0.075 mmol X kg-1 X min-1 total) into anesthetized dogs with normal kidneys (NK) and with kidneys in which the tubuloglomerular feedback mechanism was blunted by lowering renal artery pressure (LPK) or blocked by making the kidneys nonfiltering (NFK). In NK, RBF and GFR increased by 35 +/- 4% and 30 +/- 7% after 90 min of amino acid infusion, while PRNa (estimated from lithium clearance) and O2 consumption increased by 31 +/- 5% and 29 +/- 5% and distal Na+ delivery remained relatively constant. Autoregulation of RBF and GFR in response to step decreases in renal artery pressure was impaired during amino acids in NK. The hemodynamic responses to amino acids were abolished in LPK and NFK. Infusion of the nonmetabolized alpha-aminoisobutyric acid (0.075 mmol X kg-1 X min-1) into NK produced changes in renal hemodynamics that were similar to the responses observed with the four metabolizable amino acids. These data are consistent with the hypothesis that elevation of plasma amino acids increases RBF and GFR by a mechanism that requires an intact macula densa feedback. Metabolism of the amino acids does not appear to be necessary for these changes to occur.

Amino Acids↗