A technique has been developed for the quantitative estimation of perfusible glomeruli in the normal and diseased kidney. This technique is a modification of that originally described by Cook and Pickering (5). It entails the perfusion of the intact or excised kidney under standardized conditions with magnetic oxide of iron, which specifically localizes in the glomerular capillaries. The kidney is then emulsified and ground through a 100-mesh copper wire sieve and passed through an electromagnetic field. The magnetized glomeruli adhere to the glass under the influence of the magnetic field, the rest of the suspension passing through. The suspension is run through the electromagnetic field four or five times with the recovery of at least 90% of the glomeruli. The glomeruli are suspended in 30% aqueous solution of PVP and counted under microscopic vision on a scored glass microscope slide. The perfusible glomeruli and creatinine clearance of rats, ages 1 to 18 months and rabbits, ages 1 week to six months, have been determined and indicate that in the rat there is no increase in glomerular counts with maturation (mean 3.78 × 10⁴); GFR per glomerulus reaches the adult level by four weeks. In the rabbit the number of perfusible glomeruli increased from 5.5 × 10⁴ at one week to the adult level of 19.3 × 10⁴ at 1 month. There is a progressive increase in GFR per glomerulus from one week through six months, thus indicating the pattern of structural and functional maturation of the glomerulus in rat and rabbit. The collagen and non-collagen nitrogen in these animals was also studied. The techniques appear applicable to the study of the diseased kidney.

Recent evidence linking exposure toshift work to cardiovascular disease (CVD) as well as incidence of myocardial infarction seems to be greater among night shift workers compared to day workers. Repeated exposure tonight shift work causes disruptions in normal circadian patterns of blood pressure (BP) and heart rate variability (HRV), which cause anincreased risk of CVD. Recent data suggest that allowing shift workers to nap during night shifts may help to normalize BP and HRV patterns and, over time, reduce the risk of CVD. The risk of CVD related to shift work is elevated for emergency medical services (EMS) shift workers due in part to long-duration shifts, frequent use of night shifts, and a high prevalence of multiple jobs. Therefore, the effect of SBP and HRV in EMS night shift workers is analyzed through stimulated night work and it's effect on CVD is characterized.