About

William B. Lassiter is a Teaching Assistant Professor at the University of North Carolina at Chapel Hill, specializing in Statistics and Operations Research. He is based in 103 Hanes Hall and can be contacted via email at wlassite@email.unc.edu or by phone at 919-445-0087. His research interests include Statistics Education, Statistics, and Operations Research, reflecting a focus on advancing knowledge and teaching in these areas. As a faculty member within the UNC Department of Statistics & Operations Research, he contributes to the academic community through teaching and research activities.

Research topics

• Chemistry
• Internal medicine
• Endocrinology
• Medicine
• Chromatography

Selected publications

• Micropuncture Study of Glomerulotubular Balance in the Rat Kidney

  ˜The œNephron journals/Nephron journals · 2008-11-26 · 33 citations

  article

  The mechanism of glomerulotubular balance was investigated in normal rats expanded with isotonic saline and in uninephrectomized rats, both nondiuretic and expanded. Micropuncture collections were made from proximal tubules during free flow, followed by re-collections from the same sites during reduced GFR produced by partial occlusion of the renal artery or aorta. In other tubules collection was made first during reduced GFR, followed by re-collection after release of arterial compression. Transit times through proximal tubules and loops of Henle were measured with lissamine green. Similar results were obtained in all groups of rats. GFR was reduced an average of 45% by clamping. Proximal inulin F/P ratios were slightly but significantly elevated, and transit times (TT) prolonged, during reduced GFR. Velocity of tubular flow (1/TT) varied linearly with GFR. Tubular radius was unchanged during alteration in GFR, whether measured directly in photographs of the kidney surface or calculated from nephron filtration rates, TT, and inulin F/P ratios. Reabsorptive rate per unit proximal tubular volume (C/πr2) was invariably decreased with decreased GFR under steady-state conditions, but C/πr2 changed unpredictably immediately after release of the arterial clamp in the non-steady-state condition. Filtration fraction and PAH extraction were unchanged during clamping, and changes in GFR were accompanied by proportional changes in renal plasma flow. These results exclude tubular volume as a primary determinant of the proximal reabsorptive rate but are consistent with the hypothesis that colloid osmotic pressure may play a role in the control of tubular reabsorption. Alternatively, the rate-limiting factor may be the availability of energy for sodium transport, which in turn is related to renal plasma flow, et cetera.

  PublisherDOI

• Transient Vasopressin-Resistant Diabetes Insipidus of Pregnancy

  New England Journal of Medicine · 1984-02-16 · 120 citations

  article

  OSMOREGULATION is markedly altered in normal human pregnancy. Osmotic thresholds for both thirst and secretion of arginine vasopressin decrease, and plasma osmolality and sodium levels are reduced by 10 mOsm per kilogram and 4 mmol per liter, respectively, as compared with levels measured before pregnancy.1 2 3 Despite this lower osmolality, pregnant women maintain basal levels of plasma arginine vasopressin of 1 to 2 pg per milliliter — values similar to those of nongravid subjects — and concentrate their urine appropriately when they are dehydrated.3 , 4 This is all the more intriguing since two developments during normal gestation would be expected to interfere . . .

  PublisherDOI

• Phosphate Reabsorption in the Distal Convoluted Tubule

  Advances in experimental medicine and biology · 1982-01-01 · 5 citations

  article1st authorCorresponding
  PublisherDOI

• The acutely reduced kidney

  Kidney International · 1973-06-01 · 40 citations

  articleOpen access
  PublisherDOI

• Renal Tubular Permeability during Increased Intrarenal Pressure

  Journal of Clinical Investigation · 1972-03-01 · 54 citations

  articleOpen access

  Renal tubular permeability was studied by microinjection techniques during increased intrarenal pressure in anesthetized diuretic rats. Intrarenal pressure, as evidenced by intratubular pressure (ITP), was increased by elevation of ureteral pressure, partial renal venous constriction, or massive saline diuresis. Various combinations of radioactive inulin, creatinine, mannitol, sucrose, and iothalamate in isotonic saline were microinjected into superficial proximal and distal convolutions, and recovery of the isotopes was measured in the urine. Inulin was completely recovered in the urine from the injected kidney at both normal and elevated ITP. Creatinine, mannitol, sucrose, and iothalamate were also completely recovered at normal ITP, but recoveries were significantly lower, averaging 73, 85, 89, and 85%, respectively, after early proximal injection when proximal ITP was increased to 30+/-2 mm Hg by elevation of ureteral pressure. Since transit time is prolonged under these conditions, mannitol recovery was also studied during aortic constriction, which prolongs transit time but lowers ITP. Recovery was complete. A significant loss of mannitol was observed during massive saline diuresis, which shortens transit time but increases ITP. During renal venous constriction producing a proximal ITP of 30+/-2 mm Hg, mannitol recovery was significantly less than 100% even after microinjection into distal convolutions, but the loss was greater injection at more proximal puncture sites. Mannitol recovery was complete during elevation of ureteral pressure in the contralateral kidney. These studies demonstrate a change in the permeability characteristics of all major segments of the renal tubule during elevation of intrarenal pressure. This change is rapidly reversible and does not appear to be due to a humoral factor which gains access to the general circulation.

  PublisherOA PDFDOI

• Urate-2-14C transport in the rat nephron

  Journal of Clinical Investigation · 1971-01-01 · 59 citations

  articleOpen access

  Intrarenal transport of urate-2-(14)C was studied in anesthetized rats using the microinjection technic. During saline diuresis, small volumes of urate-2-(14)C (0.24-0.48 mM) and inulin-(3)H were injected into surface proximal and distal convoluted tubules, and ureteral urine was collected serially. Total (74-96%) and direct (57-84%) urate recovery increased significantly the more distal the puncture site. Delayed recovery (+/-20%) remained approximately the same regardless of localization of the microinjection. After proximal injections, total and direct recoveries of urate-2-(14)C were significantly higher in rats treated with probenecid, pyrazinoate, or PAH than during saline diuresis alone, while the excretion rates were comparable after distal injection. Delayed recovery was not altered by drug administration. The decreased proximal reabsorption of urate is presumably due to an effect of the drugs on the luminal membrane of the nephron. For perfusion at high urate concentrations, nonradioactive urate was added to the injectate (0.89-1.78 mM). Urate-2-(14)C recovery was almost complete and there was no delayed excretion, demonstrating saturation kinetics. These findings are compatible with a carrier-mediated mechanism for urate transport probably located at the luminal border of the proximal tubular epithelium. No definitive evidence for urate secretion was found in these studies.

  PublisherOA PDFDOI

• The Renal Excretion of Nitrogen Containing Metabolites

  1969-01-01 · 4 citations

  book-chapter
  PublisherDOI

• Microperfusion study of calcium transport in the proximal tubule of the rat kidney

  Pflügers Archiv - European Journal of Physiology · 1965-01-01 · 87 citations

  articleSenior author
  PublisherDOI

• Influence of ionic calcium on the water permeability of proximal and distal tubules in the rat kidney

  Pflügers Archiv - European Journal of Physiology · 1965-03-01 · 38 citations

  article1st authorCorresponding
  PublisherDOI

• Renal tubular transport of water, solute, and PAH in rats loaded with isotonic saline

  American Journal of Physiology-Legacy Content · 1965-12-01 · 141 citations

  article

  Renal tubular transport of water, osmotically active solute, and PAH were studied with micropuncture methods in anesthetized rats loaded with a volume of 0.9% sodium chloride solution equivalent to 10% of their body weight. Inulin clearance and urine flow were greatly elevated above values in nondiuretic animals, but there was little change in PAH clearance. F/P inulin-C 14 OOH ratios indicated that 42% of the filtered water and solute was reabsorbed along the proximal convolution, a lower fraction than is found in nondiuretic and hypertonic saline-loaded rats. This indicates that the rate of solute and water reabsorption in the proximal tubule did not increase in proportion to the increased filtered load, and it was, in fact, similar to that in nondiuretic rats. Intravenous administration of vasopressin and aldosterone had no demonstrable effects on solute or water reabsorption. F/P PAH/inulin ratios demonstrated that PAH secretion occurred along the proximal tubule, but probably in no other portion of the nephron.

  PublisherDOI

Frequent coauthors

• Carl W. Gottschalk

  17 shared

• Margaret Mylle

  13 shared

• John B. Stanbury

  12 shared

• K. J. Ullrich

  11 shared

• Bodil Schmidt‐Nielsen

  9 shared

• Gundula Pehling

  Novartis (Switzerland)

  8 shared

• Roberta O'Dell

  8 shared

• Mary L. Morris

  4 shared