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C Whiteside

Publications and source records attributed to C Whiteside.

48 records · Page 3Linked to original sources
PubMed1987

Postglomerular capillary solute flux restricted by shape and charge in the dog.

The permselectivity characteristics of the postglomerular (PG) microcirculation in dog kidney were investigated employing 3H-labeled cationic (DEAE) and anionic sulfated dextrans (dextran-SO4) ranging from 19 to 29 A Stokes-Einstein Radius. With the use of the multiple-indicator dilution (MID) technique, a bolus injection was made into the left renal artery and timed serial samples were obtained from renal venous and urine outflows. The injection solution contained 125I-labeled albumin (plasma reference), [14C]inulin and/or creatinine (glomerular and interstitial references), and a test [3H]dextran probe. A control run was carried out with tracer, then charge interaction was analyzed by repeating the MID run with excess unlabeled compound or after protamine sulfate infusion. After loading, renal vein recovery and mean transit time (t) were unchanged relative to [14C]inulin for [3H]dextran-SO4. But excess DEAE resulted in reduced recovery and decreased t for [3H]DEAE. After protamine sulfate, the renal vein and urine recoveries of [3H]dextran-SO4 decreased and the renal vein t increased. These findings demonstrate saturable anionic binding sites in the PG microcirculation. Under conditions where charge interaction was eliminated, the ratio of renal vein t for 125I-albumin to cationic or anionic dextran was always less than its ratio to neutral dextran, implying a larger apparent volume of distribution. We concluded that PG capillaries also limit solute flux on the basis of shape.

Animals↗
PubMed1987

Factors affecting the urinary excretion of albumin in insulin-dependent diabetes.

To determine the specificity of the urine excretion of albumin as a measure of glomerular permeability in early insulin-dependent diabetic nephropathy, the effect of variable glomerular filtration and urine flow rates on albumin, beta 2-microglobulin excretion, and the fractional renal clearance of neutral dextran (Stokes Einstein Radius 24-46 A) was examined. Five insulin-dependent diabetic subjects with normal glomerular permeability (albumin excretion less than 30 micrograms/min) and one with elevated albumin excretion (195 micrograms/min) were studied pre and post strict glucose control with constant subcutaneous insulin infusion for 7 days. The albumin excretion in the 5 subjects never exceeded 30 micrograms/min during wide variations in glomerular filtration and urine flow rates. A positive correlation between beta 2-microglobulin excretion and urine flow (r = 0.81), and glomerular filtration (r = 0.77) rates was observed. In contrast, albumin excretion showed no correlation, indicating different factors affect the excretion rate of albumin and beta 2-microglobulin. Therefore, elevated albumin excretion (greater than 30 micrograms/min) in insulin-dependent diabetes is due to increased glomerular permeability and not changes in glomerular filtration and urine flow rates, and the albumin/ beta 2-microglobulin ratio may not be a valid indicator of changing glomerular permeability. The fractional neutral dextran clearances remained unchanged with variation in glomerular filtration and urine flow rates. The sieving curve was identical in all subjects for neutral dextran 40 A, the size of albumin, suggesting that reduced glomerular charge selectivity may contribute to increased albuminuria in progressive diabetic glomerulosclerosis.

Adult↗
PubMed1984

Glomerular and postglomerular permselectivity to anionic dextrans in the dog.

Glomerular (G) and postglomerular (PG) capillary permselectivity to anionic dextran markers was investigated using the multiple-indicator-dilution (MID) technique in anesthetized mongrel dogs (n = 14). A bolus of solutes that included sulfated [3H]dextran (SO4d) homogeneous fractions 15.0-28.5 A Stokes-Einstein radius, 125I-albumin (plasma reference), [14C]inulin (G reference), and creatinine (interstitial reference) was injected into the left renal artery. Serial samples of left renal venous and urine outflows were rapidly collected. Sulfated [3H]dextran was 100% recovered, indicating no secretion or reabsorption. The urine recovery of the extracellular indicators was a measure of G extraction (EG). Mean EGSO4d/EGi (+/- SD) ranged from 0.82 +/- 0.03 to 0.48 +/- 0.02 for SO4d's 15.0-28.5 A and was invariant with renal plasma flow (F). These values were 30-50% less than the fractional EG for neutral [3H]dextrans. Postglomerular capillary extraction (EPG) was calculated from the renal vein outflow curve upslope ratios. EPGso4d/EPGcreat varied inversely with F, confirming PG diffusion limitation. Mean permeability-surface area (PS) product ratios PSSO4d/PSi (+/- SD) ranged from 0.98 +/- 0.01 to 0.55 +/- 0.04 for SO4d's 15.0-28.5 A and were consistently larger than values for neutral [3H]dextrans of the same molecular size. In contrast to G charge limitation to anionic solute flux, the PG capillaries demonstrate an increase in apparent permeability to anionic relative to neutral dextrans.

Albuminuria↗
PubMed1984

Glomerular and postglomerular transcapillary exchange in dog kidney.

The multiple-indicator dilution technique (MIDT) was used to study glomerular and postglomerular permselectivity to neutral dextran molecular weight markers in anesthetized dogs undergoing mannitol diuresis. Renal vein and urine outflow curves were obtained after an intraarterial pulse injection of 125I-labeled albumin (plasma reference), creatinine (extracellular reference), [14C]inulin, and chromatographically homogeneous 3H-labeled neutral dextrans. The urine recovery data reflect solute losses across the glomerulus. The renal vein outflow curves contain information about both glomerular and postglomerular extraction. For dextrans less than 13,500 daltons the urine transit pattern was superimposed on the glomerular markers creatinine and inulin. Relative to 125I-labeled albumin, the renal vein recoveries for creatinine, inulin, and dextrans (less than 13,500 daltons) were all equal. The renal vein mean transit time (tdextran) was greater than talbumin and less than tcreatinine. With increasing dextran size, tdextran progressively decreased. Eventually for dextrans greater than 15,500 daltons, tdextran became equal to talbumin in the renal vein, whereas urine recovery relative to inulin decreased with increasing size. Urine recovery of 3H-labeled dextran (ED) relative to inulin (Ei) provided a measure of unidirectional fractional glomerular extraction (ED/Ei). Constant infusion fractional clearance measurement of the same dextrans [U/P)D/(U/P)i) was found to equal ED/Ei obtained from the MIDT. Within the autoregulatory range of glomerular filtration, ED/Ei was invariant with reduction in renal plasma flow. Therefore, under the experimental conditions employed in the present study, diffusion across the glomerulus was negligible relative to convection. This permitted estimation of the reflection coefficients for the series of neutral dextrans. Postglomerular extraction was markedly flow dependent, which implies a major diffusion limitation. Application of a barrier-limited distributed model permitted quantitation of postglomerular capillary permeability coefficients for neutral markers of less than 5000 daltons.

Capillary Permeability↗
PubMed1983

Estrogen regulation of superoxide dismutase in normal rat mammary tissues and mammary tumors.

Multiple electrophoretic molecular variants of superoxide dismutase were demonstrated in normal rat mammary tissues and DMBA-induced rat mammary tumors. The specific activities of Cu/Zu superoxide dismutase in mammary tumors of estrogen-treated rats were not significantly different from those activities seen in normal rat mammary tissues. However, the enzyme activities of mammary tumors from untreated rats (no estrogen) were significantly lower than the activities of normal rat mammary tissues. Exogenous estrogen appeared to raise superoxide dismutase levels in DMBA-induced rat mammary tumors to those levels seen in normal rat mammary tissues.

Animals↗
PubMed1983

Determination of glomerular permselectivity to neutral dextrans in the dog.

The multiple-indicator-dilution (MID) technique was used to separate solute flux (Js) across the glomerular and postglomerular capillaries in vivo. Anesthetized mongrel dogs (n = 20) during mannitol diuresis received a pulse of extracellular indicators including 125I-albumin (plasma reference), [14C]inulin (glomerular reference), creatinine (interstitial reference), and a neutral [3H]dextran (specific mol wt between 10,000 and 24,000 dalton) in the left renal artery. Left renal venous and ureteric outflows were rapidly sampled. 3H-labeled dextrans 10,000-15,500 had renal vein mean transit times (t) greater than those of 125I-albumin, indicating postglomerular extraction. 3H-labeled dextrans greater than 15,500 had t values identical to those of 125I-albumin, indicating only unidirectional glomerular extraction. The glomerular fractional dextran extractions relative to simultaneously injected [14C]inulin (ED/Ei) were calculated from urine and renal vein outflow curves and ranged from 0.98 +/- 0.02 to 0.33 +/- 0.12 (SD) for mol wt 10,000 +/- 24,000. ED/Ei values were quantitatively identical to constant-infusion fractional clearances of the same dextrans. Renal plasma flow (RPF) was then deliberately reduced two-to threefold in the same dog. ED/Ei as measured by the MID technique remained unchanged during graded reduction in RPF. In constant-infusion experiments RPF was reduced from 5.78 to 2.77 ml X s-1 X 100 g-1 and GFR from 50.4 to 36.3 ml X min-1, but the fractional neutral dextran clearances remained constant. The predominance of convective solute flux across the dog glomerulus permitted calculation of glomerular reflection coefficients 0.03 +/- 0.06 to 0.85 +/- 0.03 (SD) for neutral 3H-labeled dextrans 10,000-24,000 dalton.

Animals↗
PubMed1983

Determination of postglomerular permselectivity to neutral dextrans in the dog.

The single-pass multiple-indicator-dilution (MID) technique was used to analyze postglomerular capillary permeability. Anesthetized mongrel dogs (n = 13) during mannitol diuresis received a pulse injection of 125I-albumin (plasma reference), [14C]inulin (glomerular reference), creatinine (interstitial reference), and a homogeneous [3H]dextran molecular weight marker 6,000-12,000 dalton in the left renal artery. Simultaneous left renal venous outflow and right and left urine were rapidly sampled. Left urine recoveries of creatinine, [14C]inulin, and [3H]dextran were identical, indicating no glomerular solute flux limitation. Progressive precession of the [14C]inulin and [3H]dextran renal vein curves relative to creatinine indicated increasing postglomerular limitation to solute flux proportional to molecular size. The postglomerular solute extraction (EPG) (renal vein upslope indicator/125I-albumin) varied inversely with postglomerular renal plasma flow (F), indicating diffusion limitation. Ouabain infusion into the left renal artery significantly reduced Na reabsorption but did not alter the EPG of [14C]inulin or [3H]dextran. Permeability-surface (PS) area products calculated from EPG and F ranged from 4.86 +/- 0.89 to 0.97 +/- 0.25 (SD) cm X s-1 X 100 g-1 for indicators 5,000-12,000 dalton. [14C]Inulin PS products remained constant for F greater than or equal to 2.50 ml X s-1 X 100 g kidney-1. PS[3H]dextran/PS[14C]In (n = 20, F greater than or equal to 2.5 ml X s-1) was used to calculate an effective postglomerular capillary pore radius, r = 55.5 +/- 7.6 (SD) A.

Animals↗
PubMedDate not supplied

Syphilis evaluation and therapy: a study of current practices in a university hospital.

The incidence of syphilis, after declining for several years, increased by 23% in the first quarter of 1987. The authors reviewed the charts of 100 patients with syphilis in order to determine how such patients were managed in a university setting. Although 77 patients met Centers for Disease Control (CDC) indications for lumbar puncture, only 11 patients had the procedure. Most patients for whom treatment was indicated either were not treated or were treated with inadequate or incorrect medications. Only 30 patients received follow-up serologic tests, and of these, only one received follow-up at the intervals recommended by the CDC. This study indicates that physicians may either be unfamiliar or disagree with the current CDC guidelines for evaluation and management of patients with syphilis. Physicians should know these guidelines and document their reasoning if they choose not to follow them. Long-term follow-up of patients with syphilis is important to ensure effective treatment and to increase understanding of this disease.

Adult↗
PubMedDate not supplied

A model for teaching critical thinking in the clinical setting.

As the scope of nursing practice changes, the ability of nurses to think critically and make appropriate clinical judgements becomes even more necessary. The author shares a model for teaching critical thinking and describes how it can be used to improve the critical thinking skills of critical care nurses.

Coronary Care Units↗
PubMedDate not supplied

Intermediate filament expression of ductal carcinoma cells in fine needle aspirates of the breast.

OBJECTIVE: To assess the frequency of occurrence of vimentin expression in fine needle aspirates of ductal carcinoma of the breast and the association of vimentin expression with established prognostic indicators. STUDY DESIGN: Cytocentrifuge preparations made from fine needle aspirates of 51 cases of ductal carcinoma were studied. RESULTS: Vimentin expression, detected in 61% of cases, was positively associated with tumor size, lymph node status, tumor grade, growth fraction and negative estrogen receptor status, but only in the case of lymph node status did the association reach the level of statistical significance. CONCLUSION: Vimentin expression can be detected in breast cancer using fine needle aspiration. Further study is necessary to determine whether it provides independent prognostic information.

Biopsy, Needle↗