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Biomedical subjects

F J Service

Publications and source records attributed to F J Service.

135 records · Page 8Linked to original sources
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Characteristics of glycemic stability.

Glucose homeostasis in healthy subjects is characterized by postmeal glucose increases of about 40 mg/dl, peaks at about 45 min, decreases close to antecibal levels 1 h after the peak, and no spontaneous oscillations until the next meal. Diabetes is characterized by progressive loss of glucose homeostasis from stable to unstable, which is directly proportional to loss of insulin secretory reserve. Degree of instability of diabetes in ambulatory subjects within a 24-h period can be expressed as mean amplitude of glycemic excursion of M-value and between two successive 24-h periods as mean of daily differences of blood glucose. Stable diabetic persons have lower values, which are closest to those of nondiabetic persons, and unstable diabetic persons have higher values. The mean diurnal blood glucose level is a measure of glycemic control. The failure to restore glycemic patterns of diabetic to those of nondiabetic persons is largely due to the failure of subcutaneously administered insulin to mimic the pattern of insulinemia of healthy subjects.

Blood Glucose↗
PubMedDate not supplied

Considerations for the programming of an open-loop insulin infusion device from the biostator glucose controller.

To assess the feasibility of preprogramming an open-loop device with insulin flow rates generated by the Biostator Glucose Controller, comparisons were made in 10 juvenile-onset diabetic patients between meals of equal size and composition taken in the morning, at noon, and in the evening and a bedtime snack during a 24-h period of Biostator glucose control. Four additional diabetic patients had Biostator glucose control for 72 h. Similar amounts of insulin were infused for the meals taken at differing times of the day and, except for the morning meal, for the same meal on two successive days. The meal-related glycemic patterns expressed as mean indices of meal excursions (MIME) were similar for meals of identical size and composition during a single day and for the same meal taken on two consecutive days. Preliminary results using an open-loop device preprogrammed by the Biostator system, although encouraging, underscore the deficiency of the subcutaneous route viz. the delayed entry of insulin into the circulation in achieving normal glucose levels and patterns.

Adult↗
PubMedDate not supplied

Pancreatic polypeptide: a marker for lean non-insulin-dependent diabetes mellitus?

Both basal and postprandial pancreatic polypeptide (PP) concentrations were exaggerated twofold in lean NIDDM patients, whereas they were normal in lean IDDM and obese NIDDM patients who were hyperglycemic as a result of partial insulin withdrawal. Insulin infusion from an artificial endocrine pancreas, which resulted in fasting euglycemia and near-normoglycemia postprandially, had no effect on PP responses in any of the diabetic patients. No postprandial PP responses were observed in totally pancreatectomized (TPX) patients. Excessive basal and postprandial concentrations of PP in diabetes appear to be related to both leanness and residual beta cell function and, therefore, potential markers for lean NIDDM.

Adult↗
PubMedDate not supplied

Use of beef ultralente for basal insulin delivery: plasma insulin concentrations after chronic ultralente administration in patients with IDDM.

Ultralente has been used as the basal component of intensive insulin therapy programs. To determine the degree to which a single daily subcutaneous injection of beef ultralente provides stable basal insulin concentrations, plasma free insulin concentrations were measured in six insulin-dependent diabetic patients over a 40-h period. All short-acting insulin was withheld during this interval. Each patient had been maintained on a chronic ultralente based program before study. Little if any evidence of a temporal peak in plasma insulin concentrations was observed. Although considerable variation in plasma insulin concentrations was observed in one individual, beef ultralente provided relatively stable plasma insulin concentrations in the group as a whole. Beef ultralente appears to be a reasonable insulin preparation to use as the basal component in an intensive insulin therapy program.

Adult↗
PubMedDate not supplied

Correlations of plasma concentrations of B-cell polypeptides with pathologic features of insulinomas.

OBJECTIVE: To assess the correlations between plasma concentrations of b-cell polypeptides (insulin, C peptide) and size, multiplicity, and malignancy of insulinomas. METHODS: We retrospectively reviewed the medical records of 55 consecutively treated patients at our institution with surgically confirmed insulinoma. The 29 female and 26 male patients ranged from 13 to 77 years of age (median, 46). Plasma insulin, C peptide, proinsulin, and glucose concentrations were analyzed statistically in patients with benign and those with malignant insulinomas. RESULTS: Significant correlations were observed between plasma insulin and tumor size (r = 0.45; P = 0.001) and tumor volume (r = 0.41; P = 0.007) and between plasma C peptide and tumor size (r = 0.38; P = 0.004) and tumor volume (r = 0.33; P = 0.025). No differences between benign and malignant tumors were noted for plasma insulin, C peptide, glucose, nor tumor size or volume. No correlations were found between plasma insulin, C peptide, or glucose and number of tumors. CONCLUSION: The plasma levels of insulin and C peptide provide qualitative indications about the size of insulinomas.

Journal Article↗
PubMedDate not supplied

Glycated hemoglobin in insulinoma.

OBJECTIVE: To determine whether preoperative levels of glycated hemoglobin (GHb) are lower in patients with functioning insulinoma and, if so, whether a distinct separation of GHb values from those in control subjects might serve for diagnosis. METHODS: We examined preoperative GHb in consecutive patients (who had this measurement done) with surgically confirmed insulinoma for the period 1983 (when the current method became available for routine use) through 1996. Hemoglobin A(1) (HbA(1)) was measured by the Isolab Glyc-Affin Test System (normal range, 4 to 7%). We studied 64 patients with insulinoma (40 women and 24 men; median age, 47.5 years; age range, 21 to 79) and 38 control subjects (25 women and 13 men; median age, 42.5 years; age range, 20 to 83) considered not to have a hypoglycemic disorder on the basis of normal results of a supervised 72-hour fast. RESULTS: HbA(1) was significantly lower in patients with insulinoma (median, 4.7%; range, 2.7 to 6.9%) than in control subjects (median, 5.3%; range, 4.1 to 6.4%) (P<0.001, two-tailed rank sum test). Among 15 patients with insulinoma treated with diazoxide preoperatively, HbA(1) was higher (median, 4.8%; range, 4.2 to 6.9%) than in patients not treated with diazoxide (median, 4.6%; range, 2.7 to 5.7%), although the difference was not statistically significant (P = 0.08). CONCLUSION: Because of considerable overlap in HbA(1) values, no GHb value was diagnostic for insulinoma; however, 16 of 64 patients (25%) with insulinoma had HbA(1) values below the lowest value (4.1%) in control subjects. Thus, HbA(1) values less than 4.1% in patients with possible insulinoma are strongly indicative of that disorder.

Journal Article↗
PubMedDate not supplied

Brittle diabetes.

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Diabetes Mellitus, Type 1↗