Approximately four decades ago, the countercurrent theory became influential in studies on the concentrating process in the mammalian kidney. The theory successfully represented the concentrating process in the outer medulla, but the problem of the concentrating mechanism in the inner medulla, as defined by Homer Smith has remained essentially intractable. In a recent comprehensive review by Kn...

Dehydration with aging is attributed to decreased urine concentrating ability and thirst. We further investigated by comparing urine concentration and water balance in 3, 18 and 27 month old mice, consuming equal amounts of water. During water restriction, 3 month old mice concentrate their urine sufficiently to maintain water balance (stable weight). 18 month old mice concentrate their urine a...

This study investigates the difference between the ability to kneel in patients after unilateral and bilateral total knee replacement. We used the Oxford knee questionnaire to assess knee function, and an additional question was introduced to identify the reasons for any difficulty or inability to kneel. Responses were received from 424 patients representing an 88.9% response rate. There was a ...

We review the cybercrime literature to draw attention to the many occasions on which authors have identified concentrations within criminal activity. We note that the existence of concentrations often leads authors to suggest that concentrations, or ‘choke points’ are amenable to effective intervention. We then discuss the reasons that concentrations are observed – it is often the result of the...

The effects of 5-hydroxytryptamine (5-HT) were investigated in red pigment concentrating hormone (RPCH)-containing neurons isolated from the X-organ of the crayfish (Procambarus clarkii). Under current-clamp conditions and using the gramicidin-perforated-patch configuration, 5-HT elicited a prolonged hyperpolarization that suppressed neuronal firing concomitant with an increase in membrane cond...

Maximum urine osmolality was measured during a 24-hour control period in normal ambulant and working subjects and hospital inpatients and compared with that achieved after intramuscular injection of 4 microgram desamino-cys-1-8-D-arginine vasopressin (DDAVP). Most of the normal subjects passed maximally concentrated urine at some time during the control period. The results suggest that in less ...

In eukaryotes, the microtubule-based spindle drives chromosome segregation. In this issue, Schweizer et al. (2015; J. Cell Biol. http://dx.doi.org/10.1083/jcb.201506107) find that the spindle area is demarcated by a semipermeable organelle barrier. Molecular crowding, which is microtubule independent, causes the enrichment and/or retention of crucial factors in the spindle region. Their results...

A number of advances which took place during the last decade have increased our understanding of the physiology and pathophysiology of urinary concentrating defects. The development of a highly sensitive radioimmunoassay for plasma vasopressin concentration has shed new light on vasopressin control mechanisms. The cellular action of vasopressin in biological membranes has been studied by variou...

The ability of the kidneys to excrete a concentrated urine is impaired together with other renal functions whenever the kidneys are progressively scarred and the amount of functioning renal parenchyma is diminished. Concentrating capacity and glomerular filtration rate are therefore reduced roughly in parallel in many common diseases which cause widespread scarring of the kidneys. The present d...