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Biomedical subjects

J Blondin

Publications and source records attributed to J Blondin.

35 records · Page 2Linked to original sources
PubMed1979

Effect of intact parathyroid hormone on hepatic glucose release in the dog.

The liver has been shown to remove parathyroid hormone (PTH) from its arterial circulation by a mechanism that is selective for the intact form of the peptide (PTH 1-84). The present studies demonstrate that PTH has biologic effects on the liver in vivo. Bovine PTH 1-84 stimulated hepatic glucose release in dogs with indwelling hepatic vein catheters from basal values of 31+/-8 to 68+/-9 mg/min per kg after bolus injections of PTH. The effect on hepatic glucose release was apparent by 5 min and persisted for the 80 min of observation. The NH(2)-terminal PTH fragment (syn b-PTH 1-34) had no effect. Bovine PTH 1-84 administered in doses designed to produce circulating levels of immunoreactive PTH similar to the endogenous levels observed in uremic dogs also increased the incorporation of (14)C from infused [(14)C]alanine into glucose, and increased estimated hepatic uptake of both chemical and [(14)C]alanine, while increasing hepatic glucose release. Thus, administration of "physiologic levels" of b-PTH 1-84 stimulated hepatic glucose release in part through increased gluconeogenesis in vivo, whereas syn b-PTH 1-34 had no demonstrable effect. Circulating levels of insulin rose after PTH administration, an increase which presumably represents a secondary response to the rise in glucose release. These results suggest that the liver is a target organ of PTH, and that PTH might potentially alter carbohydrate metabolism during hypersecretion. They also suggest that hepatic uptake of PTH may be related in part to production of a specific biologic effect rather than just simple peptide degradation.

Animals↗
PubMed1977

Chronic progressive renal disease: rate of change of serum creatinine concentration.

The rate of change of the serum creatinine concentrations in 63 patients with chronic progressive renal disease of varied etiology was examined by linear regression analysis using the logarithm or the reciprocal of the serum creatinine concentration versus time. A single straight line was described by one or the other of these relationships in 53 patients. Six patients had an accelerated rate of nephron destruction terminally (two slopes) regardless of the mathematical analysis. The remaining four patients had course changes either due to apparent spontaneous remissions or temporally related to therapy. These data suggest that (functional) nephron loss in chronic progress disease is orderly and mathematically definable. The theoretical implications are that functional nephron loss is either exponential (log Cr) or constant (1/Cr).

Chronic Disease↗
PubMed1977

Phosphate control and 25-hydroxycholecalciferol administration in preventing experimental renal osteodystrophy in the dog.

Previous studies from this laboratory demonstrated that secondary hyperparathyroidism in dogs with chronic renal disease may occur, at least in part, as a consequence of the need for progressive adaptation in renal phosphorus (P) excretion that occurs as glomerular filtration rate falls. However, the studies were of relatively short duration. Moreover, no information emerged regarding a potential role of calcium malabsorption in the pathogenesis of secondary hyperparathyroidism. The short duration of the protocol did not lend itself to the study of the effect of P control or the administration of vitamin D in the pathogenesis of renal osteodystrophy. In the present studies, 14 dogs with experimental chronic renal disease were studied serially for a period of 2 yr. Each animal was studied first with two normal kidneys on an intake of P of 1,200 mg/day. Then, renal insufficiency was produced by 5/6 nephrectomy. The dogs then were divided into three groups. In group I, 1,200 mg/day P intake was administered for the full 2 yr. In group II, P intake was reduced from the initial 1,200 mg/day, in proportion to the measured fall in glomerular filtration rate, in an effort to obviate the renal adaptation in P excretion. In group III, "proportional reduction" of P intake also was employed; but in addition, 20 mug of 25(OH)D(3) were administered orally three times a week. In group I, parathyroid hormone (PTH) levels rose throughout the 2-yr period reaching a final concentration of 557+/-70 U (normal 10-60). In group II, values for PTH remained normal throughout the 1st yr, increased modestly between the 12th and the 18th mo, but then did not rise after the 18th mo. In group III, no elevation of PTH levels was observed at any time; however, these animals were hypercalcemic. Histomorphologic analyses of the ribs of these dogs were performed serially throughout the 2-yr period. A linear relationship was obtained between the osteoclastic resorption surface and the concentration of circulating immunoreactive PTH. The osteoid volume was greater in group I animals when compared to those in group II. None of the morphologic abnormalities associated with renal osteodystrophy were observed in the animals in the third group.

Animals↗
PubMed1976

The role of lysosomal elastase in the digestion of Escherichia coli proteins by human polymorphonuclear leukocytes: experiments with living leukocytes.

Human polymorphonuclear leukocyte (PMN) elastase has been implicated in various pathological conditions. However, its physiological role remains undefined. One possible function of this enzyme may be digestion of bacterial proteins after phagocytosis. To test this hypothesis, we prepared Escherichia coli labeled with [3H]arginine and treated these bacteria with a lipid-soluble, active-site-directed chloromethyl ketone inactivator of pancreatic and granulocyte elastases (carbobenzoxy-L-glycyl-L-leucyl-L-alanine chloromethyl ketone, dissolved in methanol). Control bacteria were treated with methanol alone. When E. coli pretreated with the inactivator were incubated with solutions of porcine pancreatic elastase or with PMN granule extract, release of trichloroacetic acid-soluble radioactivity was significantly lower than in the control E. coli. Similar results were obtained when treated and control E. coli were fed to viable human PMN. In contrast, release of trichloroacetic acid-soluble radioactivity from E. coli containing [3H]thymidine was not affected by pretreatment of bacteria with elastase inactivator before feeding them to PMN, suggesting that phagocytosis of E. coli had not been inhibited by the chloromethyl ketone. When treated and control bacteria were fed to PMN, no significant difference was observed in the activity of lysosomal beta-glucuronidase recovered from post-granule supernatant fractions of homogenized leukocytes, suggesting that lysosomal degranulation had not been suppressed by the inactivator. However, elastase activity of the same fractions was depressed if the leukocytes had phagocytized chloromethyl ketone-treated E. coli, suggesting that inhibition of PMN elastase had occurred. We conclude that PMN elastase participates in digestion of E. coli proteins by human PMN.

Bacterial Proteins↗
PubMed1975

Effect of 25-hydroxycholecalciferol on calcium absorption in chronic renal disease.

Calcium absorption was measured in eight uremic patients before and after eight days of treatment with 100 or 500 mug of 25-hydroxycholecalciferol (25(OH)D3) per day. Fractional calcium absorption was estimated by administering 47Ca i.v. and orally on separate days and counting forearm radioactivity four hours later. Calcium absorption in four patients with residual renal function rose from 16.3 +/- 2.5 to 40.8 +/- 5.5% after treatment. In order to determine if the increased calcium absorption was mediated by an increase in the production of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) by virtue of increased substrate delivery to the 25-hydroxycholecalciferol-1-hydroxylase system present in the residual renal tissue, identical studies were performed in four anephric patients. Calcium absorption in these patients averaged 15.7 +/- 2.2% during the control period and rose to 46.0 +/- 11.1% after treatment. Increments in serum calcium after treatment were similar in both groups of patients; the mean concentration rose from 9.6 +/- 0.3 to 11.0 +/- 0.6 mg/100 ml. The results indicate that 25(OH)D3 can improve calcium absorption in the absence of renal tissue suggesting that its conversion to 1,25(OH)2D3 may not be necessary for its effect on the gastrointestinal tract in the uremic patient.

Absorption↗
PubMed1975

Renal function and metabolism after relief of unilateral ureteral obstruction.

In summary, the present studies indicate the presence of both functional and structural abnormalities in the postobstructed kidney involving mitochondrial integrity and deranged intermediary metabolism. It is suggested that some of these metabolic changes may account in part for the functional abnormalities observed in vivo.

Animals↗
PubMedDate not supplied

Axillary artery to iliac vein vascular access using an externally supported prosthetic graft. A new procedure for the recalcitrant secondary access patient.

The axillary artery-iliac vein graft using externally supported PTFE is a viable option for this difficult patient group. It is capable of functioning well for up to 12 months. Most importantly, despite numerous prior access procedures, the axillary artery and iliac vein in each case were amenable to the procedure. Critical technical points include the use of externally splinted PTFE grafts, avoidance of crossing joints, and angling of the graft in the direction of the iliac vein at that anastomosis. The lack of thrombosis or infection to date, coupled with successful dialysis in every patient, suggests that this is one more option that can be used in the difficult secondary access patient.

Adult↗