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Biomedical subjects

Michael R Rickels

Publications and source records attributed to Michael R Rickels.

6 recordsLinked to original sources
PubMed2025

The Heterogeneity of Type 1 Diabetes: Implications for Pathogenesis, Prevention, and Treatment-2024 Diabetes, Diabetes Care, and Diabetologia Expert Forum.

This article summarizes the current understanding of the heterogeneity of type 1 diabetes from a June 2024 international Expert Forum organized by the editors of Diabetes, Diabetes Care, and Diabetologia. The Forum reviewed key factors contributing to the development and progression of type 1 diabetes and outlined specific, high-priority research questions. Knowledge gaps were identified, and, notably, opportunities to harness disease heterogeneity to develop personalized therapies were outlined. Herein, we summarize our discussions and review the heterogeneity of genetic risk and immunologic and metabolic phenotypes that influence and characterize type 1 diabetes progression (presented as a palette of risk factors). We discuss how these age-related factors determine disease aggressiveness (along gradients) and describe how variable immunogenetic pathways aggregate (into networks) to affect β-cell and other pancreatic pathologies to cause clinical disease at different ages and with variable severity (described as disease-related thresholds). Heterogeneity of pathogenesis and clinical severity opens avenues to prevention and intervention, including the potential of disease-modifying immunotherapy and islet cell replacement. We conclude with a call for 1) continued research to identify more factors contributing to the disease, both overall and in specific subgroups; 2) investigations focusing on both individuals who surpass metabolic and immune thresholds and develop diabetes and those who remain disease free with the same level of immunogenetic risk; and 3) efforts to identify where the current type 1 diabetes staging system may fall short and determine how it can be improved to capture and leverage heterogeneity in prevention and intervention strategies.

Humans↗
PubMed2005

{beta}-Cell function following human islet transplantation for type 1 diabetes.

Islet transplantation can provide metabolic stability for patients with type 1 diabetes; however, more than one donor pancreas is usually required to achieve insulin independence. To evaluate possible mechanistic defects underlying impaired graft function, we studied five subjects at 3 months and four subjects at 12 months following intraportal islet transplantation who had received comparable islet equivalents per kilogram (12,601 +/- 1,732 vs. 14,384 +/- 2,379, respectively). C-peptide responses, as measures of beta-cell function, were significantly impaired in both transplant groups when compared with healthy control subjects (P < 0.05) after intravenous glucose (0.3 g/kg), an orally consumed meal (600 kcal), and intravenous arginine (5 g), with the greatest impairment to intravenous glucose and a greater impairment seen in the 12-month compared with the 3-month transplant group. A glucose-potentiated arginine test, performed only in insulin-independent transplant subjects (n = 5), demonstrated significant impairments in the glucose-potentiation slope (P < 0.05) and the maximal response to arginine (AR(max); P < 0.05), a measure of beta-cell secretory capacity. Because AR(max) provides an estimate of the functional beta-cell mass, these results suggest that a low engrafted beta-cell mass may account for the functional defects observed after islet transplantation.

Adult↗
PubMed2004

Cabergoline decreases somatotroph adenoma size: a case report.

Dopamine agonists have been shown to reduce growth hormone secretion in some patients with acromegaly, but their effect on adenoma size has not been well appreciated. We describe a 69 year-old woman with acromegaly caused by a somatotroph macroadenoma who received primary treatment with the dopamine agonist cabergoline. Two months after beginning cabergoline, she experienced soft tissue regression and normalization of the serum IGF-1 concentration that persisted for the remainder of the 25 months of observation. By 13 months, the volume of the adenoma by MRI was 28% of its pretreatment size, and by 25 months it was 24%. This case demonstrates that when cabergoline decreases substantially the serum IGF-1 concentration of a patient with a somatotroph macroadenoma, the adenoma size may also decrease substantially. This demonstration, plus the ease of oral administration, suggests that it would be worthwhile to study systematically the effect of cabergoline on the size of somatotroph macroadenomas.

Adenoma↗
PubMedDate not supplied

Celiac disease manifesting as isolated hypocalcemia.

OBJECTIVE: To describe a patient who presented with hypocalcemia and hypocalciuria as the initial manifestations of celiac disease, despite a normal vitamin D status. METHODS: We review the diagnostic evaluation, treatment, and biochemical and bone mineral density responses of a patient with asymptomatic celiac disease, which was initially suggested because of a low serum calcium level that became attributable to isolated malabsorption of calcium. RESULTS: A 36-year-old woman presented with hypocalcemia in the presence of normal serum 25-hydroxyvitamin D and high serum 1,25-dihydroxyvitamin D levels. She had hypocalciuria and secondary hyperparathyroidism that were refractory to pharmacologic calcium and cholecalciferol supplementation. Fecal calcium excretion indicated malabsorption of calcium, and biopsy of the small intestine demonstrated pathologic changes characteristic of celiac disease. Bone mineral density, determined by dual-energy x-ray absorptiometry, was in the osteopenic range at the femoral neck. The initiation of a gluten-free diet resulted in correction of all biochemical abnormalities and a substantial increase in bone mineral density. CONCLUSION: Primary intestinal malabsorption of calcium without concomitant vitamin D deficiency is possible in celiac disease because of the preferential involvement of the proximal small intestine early in the disease process. Our patient had hypocalcemia caused by celiac disease and values for serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D that were normal and elevated, respectively. Correction was demonstrated after dietary gluten withdrawal.

Adult↗