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C H Marshall

Publications and source records attributed to C H Marshall.

12 recordsLinked to original sources
PubMed1999

Handling 22NaCl by the blood-brain barrier and kidney: its relevance to salt-induced hypertension in dahl rats.

We previously reported that inappropriate renal vasoconstriction in Dahl salt-sensitive (DS) rats fed high NaCl diets may cause sodium retention. The present study examined the distribution and elimination of 22Na in DS and Dahl salt-resistant (DR) rats, and we determined whether an abnormality in renal function might also cause sodium retention in DS rats. Following an intravenous bolus of 4 microCi 22NaCl in prehypertensive DS and DR rats with similar blood pressures on low (0.23%) or high (8% for 4 days) NaCl diets, urinary clearance of 22Na in 1 hour was about 4 times less in DS than DR rats, and renal retention of 22Na was up to 8 times greater in DS than DR rats (P<0.01), suggesting that a renal functional defect may contribute to salt retention in DS rats; however, its uptake in tail artery, heart, lungs, liver, and spleen was similar in DS and DR rats. Uptake in brain was up to 5 times greater in DS than DR rats (P<0.01). Cerebrospinal fluid 22Na radioactivity (in counts per minute) revealed that the blood-brain barrier is 5 to 8 times more permeable to sodium in DS than DR rats (P<0.01). Cerebrospinal fluid volume and brain water content increased significantly (P<0.01) in DS but not DR rats on an 8% NaCl diet. Intracerebroventricular bolus injection of 0.06 mL of 4.5 mol/L NaCl acutely and transiently induced the same degree of hypertension in DR and DS rats, whereas similar volume injections of isotonic saline, 4.5 mol/L Na-acetate, or 4.5 mol/L NaBr did not produce hypertension in either strain. We conclude that functional abnormalities in DS rat kidneys may cause retention of NaCl and that an increased blood-brain barrier permeability to NaCl may enhance its access to sites in the brain that are then activated and induce hypertension.

Animals↗
PubMed1990

Low-dose CT of the lungs: preliminary observations.

The potential of low-dose computed tomography (CT) of the lungs was critically evaluated in two patients with normal-appearing lungs and 10 patients with a wide diversity of underlying parenchymal abnormalities. At each of five levels, in addition to routine scans obtained at 120 kVp and 140 mA, a scan at 10 mA and a half scan at 10 mA were obtained, with all other parameters held constant. Each scan was evaluated visually to assess anatomic clarity as well as the presence of artifacts and the extent of graininess. At all levels of the thorax, visualization of parenchymal structures was not affected by decreasing the milliamperage. It appears that high-quality, diagnostic images of the lung can be obtained with a very low radiation dose. Although further evaluation is necessary, the potential of low-dose CT for use in the pediatric population in particular, as well as for screening in patients at high risk for developing lung cancer, is apparent.

Humans↗
PubMed1975

Bone mineralization in the distal forearm of hemiplegic patients.

Bone mineral content was measured by single photon absorptiometry using a modified bone densitometer (Packard) with 125I as the source. In 42 hemiplegic subjects, matched for sex and age, the bone density was compared bilaterally on the radius and ulna 2 cm and 4 cm above the wrist. The nonparalyzed side served as a control for the paralyzed side. The results indicate a consistent, general loss of bone mineral on the paralyzed side compared with the nonparalyzed side. The extent of demineralization in females was greater than in male subjects. Right-dominant left-paralyzed patients showed a greater loss of bone density than right-dominant right-paralyzed subjects. The absorption ratio of the paralyzed vs the nonparalyzed sides revealed that there was a 5.3% and 7.4% decrease in the average bone density at 4 and 2 cm above the wrist, respectively. There was a progressive loss of bone mineral content relative to time after the onset of paralysis, amounting to an average of 6.4% approximately three months after the onset of injury. It was estimated that before the onset of paralysis there was an excess of bone mineral on the dominant vs the nondominant side of +5.4% and +3.2% for males and females, respectively.

Aged↗