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Biomedical subjects

K R Tuttle

Publications and source records attributed to K R Tuttle.

9 recordsLinked to original sources
PubMed1992

Lack of change of lipoprotein (a) concentration with improved glycemic control in subjects with type II diabetes.

Recently, lipoprotein (a) [Lp(a)] has been identified as a major risk factor for coronary heart disease. No data are available on the effect of improved metabolic control on plasma Lp(a) concentrations in subjects with type II diabetes mellitus, a group at high risk for coronary heart disease. We examined the effects of improved metabolic control on plasma lipid and lipoproteins and Lp(a) concentrations in 12 subjects before and after 21 days of tight metabolic control. Glycosylated hemoglobin declined from 8.9% to 6.9% (P less than .002). Lp(a) increased slightly from 21.4 to 25.8 mg/dL (P = .119) with improved metabolic control. There were no significant differences in total, low-density, or high-density cholesterol values, although the decline in triglyceride concentrations was statistically significant. The distribution of apolipoprotein (a) [apo (a)] isoforms in subjects with type II diabetes mellitus was not unusual and the apo (a) isoform patterns did not change with improved metabolic control. Although the number of subjects was small, there was no decline in Lp(a) concentrations with improved control and thus the effect of glycemic control on Lp(a) concentrations may be much smaller in type II than in type I diabetes. These results suggest that diabetic subjects with elevated Lp(a) concentrations should have intensive management of conventional cardiovascular risk factors such as high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), and blood pressure.

Blood Glucose↗
PubMed1992

Effect of insulin therapy on renal hemodynamic response to amino acids and renal hypertrophy in non-insulin-dependent diabetes.

Since renal hemodynamic disturbances are important in renal injury and are exacerbated by elevated plasma amino acid concentrations in insulin-dependent diabetes, we measured glomerular filtration rate (GFR) and renal plasma flow (RPF) after an overnight fast and during amino acid infusion in 12 patients with NIDDM and nine normal subjects. In the diabetic patients (plasma glucose 12.4 +/- 0.6 mmol/liter), the fasting GFR (113 +/- 6 vs. 98 +/- 7 ml/min.1.73 m2 in normal subjects, P = 0.056) and RPF (635 +/- 37 vs. 540 +/- 20 ml/min.1.73 m2 in normal subjects, P less than 0.05) were increased. After amino acid infusion, the increase in GFR (159 +/- 7 vs. 121 +/- 6 ml/min.1.73 m2 in normal subjects, P less than 0.05) and RPF (970 +/- 51 vs. 700 +/- 18 ml/min.1.73 m2 in normal subjects, P less than 0.05) were augmented. Insulin infusion for 36 hours did not change these responses. After three weeks of insulin therapy (plasma glucose 5.9 +/- 0.2 mmol/liter), the amino acid-stimulated GFR (143 +/- 5 ml/min.1.73 m2) and RPF (836 +/- 30 ml/min.1.73 m2) declined (P less than 0.05), while the fasting values remained unchanged. The right kidney volume was measured by ultrasonography and found to decrease after three weeks of insulin therapy from 188 +/- 12 to 165 +/- 9 ml/1.73 m2 (P less than 0.05). However, both values were greater than that in the normal subjects, 124 +/- 13 ml/1.73 m2 (P less than 0.01). Glomerular hyperfiltration and hyperperfusion became augmented during hyperaminoacidemia in our NIDDM patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Increased lipoprotein(a) concentrations in chronic renal failure.

Subjects with chronic renal failure have a greatly increased risk of coronary heart disease and dyslipidemia. Relatively few studies have examined the relationship of chronic renal failure to lipoprotein (Lp)(a) concentrations, an important risk factor for coronary heart disease. Diabetic subjects have been reported to have both increased Lp(a) concentrations and an increased risk of renal failure, thereby possibly confounding the Lp(a)-renal failure association. The association between Lp(a) and chronic renal failure in 359 control subjects and 111 subjects with renal failure was examined. Lp(a) (in milligrams per deciliter) was elevated in subjects with chronic renal failure, regardless of ethnicity (Mexican Americans, 19.8 +/- 2.7 versus 14.1 +/- 1.3; P = 0.03; non-Hispanic white patients, 24.9 +/- 3.0 versus 16.3 +/- 1.2; P = 0.006;). These differences persisted after adjustment for diabetes and ethnicity (P < 0.001). The type of treatment for chronic renal failure (diet, hemodialysis, or peritoneal dialysis) did not have an effect on Lp(a) concentrations. Lp(a) levels were not correlated with the level of creatinine in subjects with chronic renal failure. Thus, the elevation of Lp(a) levels in renal failure must occur early in renal failure, or alternatively, elevated Lp(a) levels may promote progression to chronic renal failure. These results indicate that Lp(a) concentrations are increased in chronic renal failure and may increase the risk for coronary heart disease in these subjects.

Cohort Studies↗
PubMed1991

Effect of strict glycemic control on renal hemodynamic response to amino acids and renal enlargement in insulin-dependent diabetes mellitus.

BACKGROUND: Many patients with insulin-dependent diabetes mellitus have an increase in the glomerular filtration rate and renal enlargement early in the course of their disease. Both these changes may be risk factors for the later development of diabetic nephropathy. Their cause is not known, but they could be due to augmented renal responses to the increase in plasma amino acid concentrations that occurs when dietary protein intake is high, a factor known to increase glomerular filtration and renal blood flow in normal subjects. METHODS: We measured the glomerular filtration rate and renal plasma flow after an overnight fast and during an infusion of amino acids in 12 patients with insulin-dependent diabetes mellitus and 9 normal subjects. The diabetic patients were studied when they were hyperglycemic, when they were euglycemic after an insulin infusion for 36 hours, and after intensive insulin therapy for 3 weeks. Kidney volume was measured by ultrasonography before and after the period of intensive insulin therapy. RESULTS: The glomerular filtration rate and renal plasma flow were normal after fasting when the patients were hyperglycemic (mean [+/- SE] fasting plasma glucose level, 11.5 +/- 0.7 mmol per liter). After the amino acid infusion, these values increased more in the patients (glomerular filtration rate, 2.65 +/- 0.07 ml per second per 1.73 m2 of body-surface area; renal plasma flow, 13.30 +/- 0.68 ml per second per 1.73 m2; P less than 0.05 for both) than in the normal subjects (2.25 +/- 0.08 and 11.20 +/- 0.65 ml per second per 1.73 m2, respectively). The 36-hour infusion of insulin in the diabetic patients did not alter the glomerular filtration rate or renal plasma flow either before or during the amino acid infusion. After three weeks of intensive insulin therapy (fasting plasma glucose level, 5.3 +/- 0.2 mmol per liter), the glomerular filtration rate and renal plasma flow after the amino acid infusion (2.33 +/- 0.03 and 11.30 +/- 0.43 ml per second per 1.73 m2, respectively) were similar to those in the normal subjects. The kidney volumes in the normal subjects and the patients with diabetes were 219 +/- 14 and 312 +/- 14 ml per 1.73 m2, respectively (P less than 0.01); the volume decreased to 267 +/- 22 ml per 1.73 m2 (P less than 0.001) in the diabetic patients after three weeks of intensive insulin therapy, which was not significantly different from the volume in the normal subjects (P = 0.1). CONCLUSIONS: Conventionally treated diabetic patients who have normal renal function while fasting have augmented renal hemodynamic responses to increased plasma amino acid concentrations. The concomitant decrease in these hemodynamic responses and in kidney size with strict glycemic control suggests that these phenomena are related and influenced by the metabolic state.

Adult↗
PubMed1991

Altered renal calcium handling in hypercalcemia of malignancy.

It has been controversial whether increased renal tubular calcium reabsorption contributes to hypercalcemia in patients with malignancies. Moreover, whether this abnormality is associated with volume depletion, a parathyroid hormone-like effect, or other mechanisms has not been clarified. Eight consecutive patients with hypercalcemia due to a variety of tumor types were studied in detail. The glomerular filtration rate (iothalamate clearance) was reduced in all patients (0.98 +/- 0.10 (mean +/- SE) mL/s.1.73 m2; P less than 0.001) compared with normal controls (N = 9) (1.93 +/- 0.08 mL/s.1.73 m2), but it was similar to that in controls matched for renal insufficiency (N = 6) (1.15 +/- 0.05 mL/s.1.73 m2). During hypercalcemia produced by calcium infusion, urinary calcium excretion (millimoles of calcium per liter of glomerular filtrate) was increased in controls with renal insufficiency compared to those with normal renal function (P = 0.028). In all patients with hypercalcemia of malignancy, urinary calcium excretion was decreased compared with controls with renal insufficiency, but it was low in only five of eight patients compared with normal controls. Extracellular fluid volume (iothalamate volume of distribution) was not decreased in any patient, and urinary cAMP and/or plasma parathyroid hormone-like bioactivity were increased in six of eight patients. After treatment with an inhibitor of bone resorption, aminopropylidene 1,1 diphosphonate, abnormal renal calcium handling was not detected if the serum calcium normalized. It was concluded that increased renal tubular calcium reabsorption was consistently present in patients with hypercalcemia of malignancy compared with controls matched for renal insufficiency, but the proportion with the abnormality was underestimated if normal controls were used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Decrease of lipoprotein(a) with improved glycemic control in IDDM subjects.

OBJECTIVE: Recently, lipoprotein(a) [Lp(a)] has been identified as a major risk factor for coronary heart disease. There are few data available on the influence of metabolic control on plasma Lp(a) concentrations in subjects with insulin-dependent diabetes mellitus (IDDM), a group at high risk for coronary heart disease. RESEARCH DESIGN AND METHODS: We examined the effects of improved metabolic control on plasma lipid and lipoproteins and Lp(a) concentrations in 12 subjects before and after 21 days of tight metabolic control. RESULTS: Glycosylated hemoglobin declined from 8.4 to 6.9% (P less than 0.001), and Lp(a) declined from 29.7 to 27.1 mg/dl (P = 0.022). There were no significant differences in total, low-density lipoprotein, or high-density lipoprotein cholesterol, although the decline in triglyceride concentrations were borderline statistically significant. The distribution of apolipoprotein(a) isoforms in IDDM patients was not unusual, and the apolipoprotein(a) isoform phenotypes did not change with improved metabolic control. Lp(a) concentrations were also significantly higher than in a population-based control group of nondiabetic subjects from the San Antonio Heart Study. CONCLUSIONS: Although the number of subjects was small and the degree of improvement in metabolic control was modest, the results suggest that improved metabolic control may decrease the risk of coronary heart disease mediated by Lp(a) in IDDM.

Adult↗
PubMed1990

The natural history of diabetic nephropathy.

Diabetic nephropathy is now the most common cause of ESRD in the US, and no other complication of diabetes is associated with more deaths. In addition to its impact on morbidity and mortality, it extracts a tremendous cost from the health-care economy. Prevention and better treatment of diabetic renal disease should be a high priority for both the health-care system and society at large. Ultimately, diabetic nephropathy should be preventable, but that goal can be accomplished only by the coordinated efforts between investigators, who work to uncover pathophysiologic processes and design new treatments, and clinicians, who take those findings to the patient's bedside.

Diabetes Mellitus, Type 1↗
PubMed1988

Glucagon, not insulin, may play a secondary role in defense against hypoglycemia during exercise.

The sympathochromaffin system, probably sympathetic neural norepinephrine, plays a primary role in the prevention of hypoglycemia during exercise in humans. Our previous data indicated that changes in pancreatic islet hormones are not normally critical but decrements in insulin, increments in glucagon, or both become critical when catecholamine actions are blocked pharmacologically. To distinguish between the role of insulin and that of glucagon in this secondary line of defense against hypoglycemia during exercise in humans, glucoregulation during moderate exercise (approximately 55% of maximum O2 consumption over 60 min) was studied in people who could not decrease insulin but could increase glucagon, i.e., patients with insulin-dependent diabetes mellitus (IDDM). While receiving constant intravenous infusions of regular insulin, in individualized doses shown to result in stable plasma glucose concentrations of approximately 95 mg/dl before exercise, patients with IDDM were studied under two conditions: 1) a control study (n = 13) and 2) an adrenergic blockade study (propranolol infusion, n = 8). In the control study, mean plasma glucose concentrations did not change (from 95 +/- 2 to 100 +/- 11 mg/dl) during exercise despite constant plasma free insulin levels. In the adrenergic blockade study plasma glucose declined (from 96 +/- 2 to 74 +/- 7 mg/dl, P less than 0.01) but stabilized; hypoglycemia did not occur. Exercise-associated increments in plasma glucagon were comparable in the two studies. These data confirm that decrements in insulin are not critical to the prevention of hypoglycemia during moderate exercise in humans and indicate that compensation for deficient catecholamine action does not require decrements in insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗