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Biomedical subjects

J D Barber

Publications and source records attributed to J D Barber.

8 recordsLinked to original sources
PubMed1994

Acute beneficial effect of Fluosol-DA on urinary excretion of stroma-free hemoglobin in the isolated rat kidney.

In a timed study over 75 min, divided into 5 15-min periods, experimental perfusions of isolated rat kidneys using Krebs-Ringer bicarbonate (KRB) containing 3.5% (uncrosslinked) stroma-free hemoglobin (SFH) plus 3.5% of the perfluorochemical Fluosol-DA were found to excrete only 13% as much total hemoglobin (Hb) as control perfusions using KRB containing 7% SFH alone (controls). The glomerular filtration rate was the same for experimentals and controls in 3 periods, and slightly higher in the experimentals in 2 periods. However, urine flow was found to be significantly decreased in all 5 periods for the experimentals relative to the controls. These effects can be explained by reabsorption of glomerular filtrate containing Hb by endocytosis of renal tubular cells.

Animals↗
PubMed1992

Telling the public the real health cost story.

The real causes of hospital cost increases originate with societal problems like poverty, lack of education, drug abuse, and violences, the author contends. In addition, rampant consumerism and an irrational delivery system play a part in cost increases. Health care professionals need to understand these causes and be able to explain them to their acquaintances outside the field, the author says.

Economics, Hospital↗
PubMed1992

Amelioration of nephrotoxicity associated with synthetic oxygen transport media.

Use of synthetic oxygen transport media offers the potential advantages of reducing requirements for coadministration of blood products and oxygen at the scene of mass casualty situations. Previous studies have shown perfusions of isolated kidneys with stroma-free hemoglobin (SFH) to be physiological while those with Fluosol-DA (20% FDA) have been associated with low glomerular filtration rate, urinary flow rate, and fractional reabsorption of sodium and potassium (FrNa+ and FrK+). In the present studies, perfusions with SFH/FDA mixtures showed normal glomerular filtration rate, a 50% lower urinary flow rate, and FrNa+ values 3% to 5% higher than SFH controls. Compared with 20% FDA perfusions, nephrotoxic effects of SFH/FDA combinations were moderate. Compared with SFH/FDA mixtures, perfusion with 20% FDA showed lower urinary flow and glomerular filtration rates. Ultrastructural assessment of glomerular filter revealed that FDA emulsion particles were adherent to epithelial podocytes. We conclude that resuscitation with a mixture of SFH and FDA may ameliorate the previously reported nephrotoxicity associated with the use of FDA alone.

Animals↗
PubMed1990

Reduced renal perfusion pressure causes prostaglandin-dependent excitation of R2 chemoreceptors in rats.

The activity of multiunit preparations of afferent renal nerve activity (ARNA) and single R2 chemoreceptors was recorded during graded reductions in renal perfusion pressure (RPP) produced by tightening an aortic snare in anesthetized rats. In 13 multiunit preparations an initial RPP reduction from 117 +/- 2 to 101 +/- 2 mmHg caused ARNA to increase 29 +/- 5% above control. Further reductions in RPP produced a 65 +/- 11% increase in ARNA at 80 +/- 1 mmHg, 87 +/- 24% at 59 +/- 1 mmHg, and 127 +/- 38% at 37 +/- 1 mmHg (P less than 0.01 ARNA vs. RPP). Renal blood flow was measured by pulsed Doppler flowmeter in these rats and showed good autoregulation and minimal reduction (-4 +/- 2%) during the initial pressure drop. Ten single R2 chemoreceptors increased their firing rate by 129 +/- 4% when RPP was reduced from 109 +/- 2 to 85 +/- 2 mmHg and showed a peak response of 494 +/- 105% at 27 +/- 2 mmHg. The activity of 11 R2 receptors increased from 3.7 +/- 1.0 to 6.8 +/- 0.8 impulses/10 s when RPP was reduced from 112 +/- 4 to 79 +/- 2 mmHg. Prostaglandin blockade with indomethacin (6 rats) or meclofenamate (7 rats) caused a decrease in basal activity in the same units to 1.8 +/- 0.5 impulses/10 s and eliminated their excitatory response to a similar reduction in RPP (108 +/- 4 to 75 +/- 3 mmHg). These data support a role for R2 chemoreceptors in neurocirculatory reflexes elicited by reductions in RPP.

Afferent Pathways↗
PubMed1986

Prostaglandin blockade impairs denervation diuresis and natriuresis in the rat.

Acute unilateral renal denervation of control rats produced an ipsilateral diuresis (5.5 +/- 0.8 to 10.0 +/- 1.0 microliter/min, P less than 0.01) and natriuresis (579 +/- 202 to 2,668 +/- 225 neq/min, P less than 0.01) without a significant change in glomerular filtration rate or effective renal plasma flow. Inhibition of prostaglandin synthesis with indomethacin or meclofenamate (4 mg/kg iv) after acute unilateral denervation eliminated the diuresis (13.3 +/- 1.6 to 5.0 +/- 0.9 microliter/min, P less than 0.01) and attenuated the natriuresis (3,098 +/- 462 to 1,097 +/- 163 neq/min, P less than 0.01). Denervation diuresis and natriuresis were significantly impaired to the same extent when denervation was performed after inhibition of prostaglandin synthesis (3.2 +/- 0.3 to 4.9 +/- 0.4 microliter/min, NS; and 490 +/- 154 to 1,036 +/- 274 neq/min, P less than 0.05 vs. control, respectively). These results indicate that the natriuresis and diuresis seen after acute unilateral denervation in anesthetized rats are highly dependent upon prostaglandins and cannot be initiated or maintained when prostaglandin synthesis is impaired by indomethacin or meclofenamate.

Animals↗
PubMed1985

Nephrotoxic effects of oxygen transport media in the isolated rat kidney.

Perfusion of isolated kidneys from rats demonstrated the following nephrotoxic effects of Fluosol-DA: decreased glomerular filtration rate (GFR), urine flow rate (UFR), and fractional reabsorption of potassium (FrK+) (P less than 0.01). Fluosol-DA perfusions were at flow rates about equal to the physiologically normal rodent renal plasma flow rate of 4 ml/min. Stroma-free hemoglobin (SFH) perfusions, also at 4 ml/min, were associated with physiologically normal renal functions, as were those of control Krebs-Ringer bicarbonate (KRB) perfusions at 32 ml/min.

Animals↗
PubMed1980

Asynchronous independent lung ventilation (AILV).

A new technique is described for selective lung ventilation of patients with predominantly unilateral pulmonary pathology. Separate ventilators were used to inflate each lung via a double lumen endobronchial tube and no attempt was made to synchronize them. In three of the four cases, there was considerable improvement in respiratory function and radiographic appearance. In no case was there any cardiovascular depression. The use of a new endobronchial tube, the "broncho-cath", suitable for this technique is also described.

Adult↗