Insulin secretion and glucose uptake in hypomagnesemic sheep fed a low magnesium, high potassium diet

Hyperglycemic and euglycemic clamp experiments were conducted to evaluate insulin secretion and glucose uptake in the hypomagnesemic sheep fed a low magnesium (Mg), high potassium (K) diet. Five mature sheep were fed a semipurified diet containing 0.24% Mg and 0.56% K (control diet) and five were fed 0.04% Mg and 3.78% K (low Mg/high K diet) for at least 2 weeks. In the hyperglycemic clamp experiment, plasma glucose concentrations were raised and maintained at a hyperglycemic steady-state (approximately 130 mg/100 ml) by variable rates of glucose infusion during the experimental period (120 minutes). The insulin response in the sheep fed the low Mg/high K diet (31.0 microU/ml) were significantly (P < 0.01) lower than those (111.7 microU/ml) of the sheep fed the control diet. In the euglycemic clamp experiment, insulin was infused at rates of 5, 10, 15, or 20 mU/kg/min, each followed by variable rates of glucose infusion to maintain a euglycemic steady-state (basal fasting levels). Hypomagnesemic sheep fed the low Mg/high K diet had significantly (P < 0.01) lower mean glucose disposal (3.72 mg/kg/min) across the insulin infusion rates compared with those of the sheep fed the control diet (5.37 mg/kg/min). These results suggest that glucose-induced insulin secretion and insulin-induced glucose uptake would be depressed in hypomagnesemic sheep and are caused by feeding the low Mg/high K diet.

Insertion/deletion polymorphism in intron 16 of the ACE gene and left ventricular hypertrophy in patients with end-stage renal disease

We studied the relationship between polymorphism in intron 16 of the angiotensin-converting enzyme (ACE) gene and left ventricular (LV) hypertrophy in uremic patients treated with hemodialysis therapy. The LV parameters were not different for age-, hematocrit-, and blood pressure-matched patients in DD, ID, and II genotype groups. The most important factor for LV hypertrophy was systolic blood pressure, which correlated with the posterior wall thickness (r=0.35; P=0.001) and LV mass index (LVMI; r=0.23; P=0.032). Among nonhypertensive patients, the frequency of interventricular septum (IVS) hypertrophy (>12 mm) and hypertrophy in LVMI (>145 g/m2) was significantly greater in patients with the DD genotype than in I allele-positive (+) patients. The odds rate for IVS hypertrophy was 5.04 (95% confidence interval, 1.15 to 24.8). These data suggest that the DD genotype of the ACE gene polymorphism is a contributory factor for the development of LV hypertrophy in patients with end-stage renal disease (ESRD).

Cloning of mouse prolidase cDNA: predominant expression of prolidase mRNA in kidney

We cloned mouse prolidase cDNA from a mouse liver cDNA library. Homology to human prolidase is 83.2% at the nucleotide level and 87.2% at the amino acid level. Northern blot analysis showed that while prolidase mRNA was transcribed in brain, heart, liver, and muscle, it was predominantly transcribed in kidney.

[A case of mesangioproliferative glomerulonephritis (GN) associated with unique lesions of juxtaglomerular apparatus (JGA) and interstitium]

A case of mesangioproliferative glomerulonephritis (GN) associated with unique lesions of the juxtaglomerular apparatus (JGA) and interstitium is discussed. A 31-year-old Japanese woman who developed eyelid and pretibial edema with nephrotic-range proteinuria (4.8 g/day) and without hematuria, was admitted. Her proteinuria and edema quickly disappeared within 7 days after admission without treatment. Her blood examinations revealed hypocomplementemia on admission, but complement recovered to normal levels after 4 weeks. A renal biopsy specimen obtained on the 5th day of admission revealed moderate mesangioproliferative GN with marked periarteriolar inflammatory cell infiltrations in the JGA and occasionally in the tubular interstitium. Depositions of IgG, IgA, IgM and C3 were observed in the glomerular mesangial regions and some capillary walls, but not in the extraglomerular areas. Titers of GN-related viral antigens were not increased. Although the renal histology of this case was similar to that of experimental acute cytomegalovirus (CMV) GN in mice (described by Smith, R.D.), we could not detect CMV antigen by indirect immunofluorescent method or the virus-like particles by electron microscopy. Clinical cases of nephropathy combining lesions of the glomerulus, JGA, and interstitium are very rare. We herein report a patient with mesangioproliferative GN, who underwent an acute clinical course associated with unique inflammatory lesions of the JGA and/or interstitium.

Combined effects of diet and cold exposure on insulin responsiveness to glucose and tissue responsiveness to insulin in sheep

Hyperglycemic clamp and hyperinsulinemic euglycemic clamp techniques were used to investigate effects of diet and cold exposure on insulin responsiveness to glucose and tissue responsiveness and sensitivity to insulin in adult rams. The sheep were fed a high-concentrate diet (80% concentrate and 20% roughage) and a high-roughage diet (20% concentrate and 80% roughage), both 70% above the ME requirement for maintenance, and were exposed to a thermoneutral environment (20 degrees C) and a cold environment (0 degrees C) for 2 wk. The estimated ME intake was greater (P < .01) for the high-concentrate diet than for the high-roughage diet. In the hyperglycemic clamp experiment, the ratio of the plasma insulin increment to the glucose infusion rate (insulin responsiveness to glucose) was lower during cold exposure than in the thermoneutral environment in sheep fed the high-concentrate diet but was unchanged in sheep fed the high-roughage diet. In the hyperinsulinemic euglycemic clamp experiment, the glucose infusion rate (tissue responsiveness to insulin) was higher (P < .01) for the high-concentrate diet than for the high-roughage diet, and it was also higher (P < .01) during cold exposure than in the thermoneutral environment, indicating that tissue responsiveness to insulin was intensified in sheep fed the high-concentrate diet during cold exposure associated with the higher energy intake. These results suggest that both reduced insulin responsiveness and enhanced tissue responsiveness to insulin in sheep exposed to cold were dependent on the type of diet.

[The oral 1-25 dihydroxyvitamin D3 pulse therapy in hemodialysis patients for the early treatment of secondary hyperparathyroidism]

It is said that maintenance hemodialysis patients are already suffering from secondary hyperparathyroidism (2HPT) from early stage of chronic renal failure. The treatment of 2HPT in this stage is very important for preventing renal osteodystrophy (ROD). But many long-term dialysis patients are still afflicted with ROD although vitamin D have been used for treatment. In this study, an oral administration of 1-25 (OH)2 D3 (4 micrograms) with pulse therapy twice a week at the day before hemodialysis was started for 12 weeks. The concentration of 1-25 (OH)2D3, total calcium (Ca), ionized calcium (Ca++), alkaline phosphatase (ALP) and parathyroid hormone (PHT) in serum were measured not only before and after every 2 hours of administration a day, but also for 12 weeks after that. The peak of serum 1-25 (OH)2D3 could be sufficiently elevated after 8 hours, and the slight peak of Ca++ could be seen after 8 hours as well. But the level of total calcium could not increased. Although the level of only HS-PTH has not increased after 24 hours, a significant reduction in serum level of C-PTH, intact-PTH and HS-PTH could be recognized after 12 weeks finally. This pulse therapy was effective in reducing the serum level of PTH in this early stage from beginning hemodialysis. But, it needs further studies for the standard treatment.

Insulin responsiveness to glucose and tissue responsiveness to insulin over the feeding cycle in sheep

Insulin responsiveness to glucose and tissue responsiveness to insulin, using the hyperglycemic clamp and the hyperinsulinemic euglycemic clamp techniques, were measured before, during and after feeding in sheep fed an alfalfa hay and commercial concentrate diet. Glucose infusion rate and the plasma insulin increment in the hyperglycemic clamp experiment were higher during the feeding period (0 to 1 h after initiating feeding) than during the pre- and post-feeding periods. The ratio of plasma insulin increment to glucose infusion rate remained unchanged over the feeding cycle. Only a slight increase (P less than .05) in the glucose infusion rate was observed during feeding in the hyperinsulinemic euglycemic clamp experiment. These results suggest that insulin responsiveness to glucose tends to be enhanced during the feeding period but that tissue responsiveness to insulin is not changed over the feeding cycle in sheep.