The object of this work is to try to elucidate the role of genetic and environmental factors in the aetiology of diabetes by studying a series of identical twins.Concor&ince in identical (monozygotic) twins does not necessarily mean that a disease is genetic in origin. Twins usually live together in early life and thus share the same environment. Concordance could therefore be the result of genetic or environmental similarity. However, in later life most twins live apart and then concordance does suggest a genetic disease. Discordance, on the other hand, must indicate that a disease is due, at least in part, to nongenetic factors. We are therefore particularly interested in discordance in younger and concordance in older twins. Previous Twin StudiesThere have been five large studies of diabetic twins [1-5] but all have defects; none has categorised the twins as insulin dependent diabetics (IDDs) or noninsulin dependent diabetics (NIDDs) and in 0nly two were the unaffected twins examined by glucose tolerance.Then Berg [1] reported 47 identical twin pairs of whom 35 were over 43 years old. All of these were concordant for diabetes on history or glucose tolerance testing, but of the 12 younger twin pairs only 6 were concordant. White [2] found 16 of 33 pairs to be concordant but did not categorise them by age or type of diabetes. Gottlieb and Root [3] who, like White, worked at the Joslin Clinic but, we assume, were reporting on different patients, found seven out of 10 pairs in whom diabetes was diagnosed over the age of 40 were concordant, compared to only two out of 20 younger twins. Harvald and Hauge [4] ascertained twins from the Danish twin register. Of 47 "maturity-onset" pairs 26 were concordant, of 36 younger onset pairs only 12 were concordant but unaffected twins were not tested. Pollin et al [5] studied 53 identical twin pairs among US ex-service men aged 43 to 53 and found only three pairs were concordant but again unaffected twins were not tested.All but one of these studies have also reported concordance rates in non-identical twins. Then Berg [1] found nine out of 50 pairs of non-identical twins to be concordant, White [2] two out of 63, Gottlieb and Root [3] two out of 70 and Harvald and Hauge [4] 22 out of 158. The overall figure for concordance in nonidentical twin pairs in these four studies is 35 out of 341 (10%).In spite of the limitations of these studies three broad conclusions can be drawn. 1) Identical twins always show a higher concordance rate than non-identical twins irrespective of their age at diagnosis.2) Younger onset pairs of identical twins are often discordant for diabetes.3) Older onset pairs, on the other hand, are usually concordant for diabetes.Our own previous results [6] confirm these general conclusions. Of 96 pairs of identical twins 59 index twins became diabetic before the age of 40, 31 were concordant and 28 discordant; of the 37 pairs in which the index twin was diagnosed after the age of 40 all but three were concordant. Similar proportions were found as the study has...
ABSTRACT. Neutrophil granulocyte chemotaxis and intraneutrophilic and plasma levels of lysozyme as well as the number of T and B lymphocytes and lymphocyte transformation in vitro on stimulation with mitogens and microbial antigens were studied in four groups of patients with diabetes mellitus (DM). Twelve patients with insulin‐dependent diabetes mellitus (IDDM) and ketoacidosis and 4 patients with non‐insulin‐dependent diabetes mellitus were studied at the time of diagnosis and before and after start of treatment. Ten patients with IDDM of less than 10 years' duration which had been difficult to regulate well and 10 patients with IDDM well regulated for more than 20 years were studied at their regular outpatient visits. Apart from a slight increase in plasma lysozyme in group 1 from the first to the second examination, we found no differences between diabetics and healthy control persons. It is concluded that if patients with DM are more susceptible to infections, it is probably caused by elements of neutrophil or lymphocyte function not examined in this study or by factors unrelated to immunity.
To elucidate the remission phase in juvenile diabetics the insulin release, insulin content, and glucose utilization were measured in isolated Langerhans' islets from mice maintained for 6 days in a tissue culture at a glucose concentration of 278 mmol, followed by a culture period of 4 days at 6.1 mmol glucose. These experiments revealed that the ability of the islets to store and secrete insulin during glucose stimulation decreased considerably during incubation at high concentrations of glucose. When the glucose concentration in the incubation medium was reduced, these properties could be re-established. Basal as well as glucose-stimulated glucose utilization increased greatly during incubation at high glucose concentrations. However, it was not possible to normalize the glucose utilization during 4 days' incubation at 6.1 mmol glucose. The results indicate that unphysiologically high concentrations of glucose may induce long-lasting changes in the function of Langerhans' islets.
Summary. Islets of Langerhans from NMRI-mice were kept for one week in tissue culture in medium supplemented with human serum obtained from either normal healthy subjects or newly diagnosed juvenile diabetic patients before insulin treatment. Islets cultured in diabetic serum released more insu, lin than islets cultured in normal serum, whether tissue culture medium 199 with 5.5-8.3 mmol/1 glucose and 10% serum, or culture medium RPMI 1640 with 11 mmol/1 glucose and 0.5% serum were used. Islets kept for one week in culture with diabetic serum did not show any decrease in DNA content or glucose induced insulin secretion and biosynthesis. It is concluded that serum from newly diagnosed insulindependent diabetic patients stimulates insulin release from isolated mouse islets kept in tissue culture. The underlying mechanism is unknown.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.