Reversal of diurnal variation in renal function in cases of cirrhosis with ascites

The intrinsic circadian clock in podocytes controls glomerular filtration rate

Glomerular filtration rate (GFR), or the rate of primary urine formation, is the key indicator of renal function. Studies have demonstrated that GFR exhibits significant circadian rhythmicity and, that these rhythms are disrupted in a number of pathologies. Here, we tested a hypothesis that the circadian rhythm of GFR is driven by intrinsic glomerular circadian clocks. We used mice lacking the circadian clock protein BMAL1 specifically in podocytes, highly specialized glomerular cells critically involved in the process of glomerular filtration (Bmal1^lox/lox/Nphs2-rtTA/LC1 or, cKO mice). Circadian transcriptome profiling performed on isolated glomeruli from control and cKO mice revealed that the circadian clock controls expression of multiple genes encoding proteins essential for normal podocyte function. Direct assessment of glomerular filtration by inulin clearance demonstrated that circadian rhythmicity in GFR was lost in cKO mice that displayed an ultradian rhythm of GFR with 12-h periodicity. The disruption of circadian rhythmicity in GFR was paralleled by significant changes in circadian patterns of urinary creatinine, sodium, potassium and water excretion and by alteration in the diurnal pattern of plasma aldosterone levels. Collectively, these results indicate that the intrinsic circadian clock in podocytes participate in circadian rhythmicity of GFR.

Charles Bernard Puestow (1902-1973): American surgeon and commander of the 27th Evacuation Hospital during the Second World War

Dr. Charles Bernard Puestow (1902-1973) was an American surgeon who is well known for developing the longitudinal pancreaticojejunostomy, which is known as the "Puestow procedure" in his honor. Puestow served in the American military during the Second World War and commanded the 27th Evacuation Hospital, which provided medical and surgical services to wounded individuals in Europe and North Africa. In 1946, he founded the surgical residency training program at the Hines Veterans Hospital, which was the first such program in the United States based at a veterans hospital.

Patterns of urine flow and electrolyte excretion in patients following traumatic brain injury

This study was conducted to determine how commonly, following a traumatic brain injury (TBI), patients might lose their circadian rhythm of urine production and to explore possible causes. In health, an adult would be expected to have a daytime rate of urine production twice that of the night. Seven patients, all more than three months post-TBI, who were either continent or in whom continence could be achieved by use of an external device (convene) were investigated. For each patient, over a five-day period, the mean daytime and night-time rates of urine production were measured. These values were expressed as a ratio. In three of the seven patients this ratio did not differ significantly from 1, suggesting that they had lost their normal circadian rhythm of urine production. Screening of pituitary function implicated hypothalamic dysfunction in six of the seven patients, offering a possible explanation for the loss of circadian rhythm seen.

Do hypertensive patients have a different diurnal pattern of electrolyte excretion?

Studies generally indicate that excretion of sodium, potassium, and water is greater during the day than during the night. To determine whether hypertensive patients exhibit this same pattern of excretion, diurnal variations in excretion of sodium, potassium, creatinine, and water were examined in 107 hypertensive men and women from a clinical trial on control of hypertension by nonpharmacological means--the Hypertension Control Program. Each participant provided two carefully timed 24-hour urine collections divided into daytime and overnight specimens. The median ratios of 24-hour to 8-hour overnight excretion were 2.84, 3.95, 2.99, and 2.77 for sodium, potassium, creatinine, and water, respectively. Thus, more than half of this hypertensive group exhibited a greater rate of sodium and water excretion during sleep than during daytime hours, a reversal of the usual pattern. When the group was subdivided based on age, sex, race, trial randomization group, use of diuretics, and hypertension severity, women had significantly lower ratios of 24-hour to overnight excretion for sodium and water than men and blacks had significantly lower 24-hour to overnight ratios for water and potassium than whites. When the 24-hour to overnight ratios for these hypertensive patients were compared with those for a group of 30 men and women with high-normal blood pressure, those with high-normal blood pressure had significantly larger ratios for sodium and water excretion than the hypertensive group. The results of this study suggest that hypertensive patients may have a different diurnal pattern of sodium and water excretion than normotensive subjects and that further research is needed to clarify this issue.