The incidence and prevalence of type-1 diabetes mellitus

AIM: To determine the incidence, prevalence of type-1 diabetes mellitus (DM) and the presence of islet-cell antibodies (ICAs) in people of African ancestry in the Bahamas. METHOD: Hospital records of type-1 DM were reviewed. Seventeen consecutive patients had postmeal C-peptide and ICA determined. RESULTS: The incidence and prevalence of type-1 DM in the Bahamas were: incidence:- 10.1/100 000, age 0-14 years; and prevalence- 31/100 000, age 0-24 years. Only two out of 17 (11.8 per cent) patients had ICAs. CONCLUSION: Type -1 DM is common in children of African ancestry in the Bahamas. ICAs were absent in the majority of patients.

Streptozotocin alters pancreatic beta-cell responsiveness to glucose within six hours of injection into rats

A 24-hour glycaemic profile following streptozotocin (80 mg/kg. ip) injection was investigated in fasted rats. The most prominent changes in blood glucose were hyperglycaemia associated with low levels of plasma insulin after two hours followed by hypoglycaemia associated with high levels of plasma insulin after six hours; subsequently hyperglycaemia progressively developed and this was associated with decreasing levels of plasma insulin. Further probing revealed that at two hours after streptozotocin injection, the pancreatic á-cells could not respond to an oral glucose load while, at six hours after, there was an apparent return of á-cell responsiveness, but subsequently á-cell responsiveness was progressively lost and histological examination revealed cellular damage. From these results, it is concluded that within six hours of injection, stretozotocin initiates pancreatic á-cell damage which leads to the development of diabetes mellitus. (AU)

Ultrastructure of the Islets of Langerhans in protein-energy malnutrition

Significant hormonal changes have been reported in childhood malnutrition, including high serum levels of growth hormone and cortisol, and low levels of circulating insulin. The ultrastructure of the endocrine pancreas in such patients has hitherto not been reported. A light microscopy survey of the pancreatic islets was carried out on 69 malnourished children dying from protein-energy malnutrition. In seven of these cases, a rapid autopsy protocol allowed tissues to be fixed for electron microscopy within 75 minutes of death. This paper presents the first ultrastuctural observations on the Islets of Langerhans in childhood protein-energy malnutrition. In all cases, there was a variable degree of degereration of all cell types with membrane damage, loss of ribosomes, vesiculation and mitochondrial swelling. In addition, the B-cells showed a high proportion of precursor granules compared to crystal forms, possibly accounting for low insulin serum levels reported by other workers. It is suggested that islet cell changes may be related to free radical damage secondary to depletion of glutathione and other antioxidants, as well as relative deficiencies of cysteine and zinc. In addition, the effects of agonal anoxia, and a short fixation delay after death must be considered. (AU)

Renal subcapsular islet cell transplantation in the dog: a preliminary report

During the last two decades, islet cell transplantation has been pursued both experimentally and clinically in an effort to ameliorate diabetes mellitus. At present, however, islet cell transplantation still remains at the experimental stages as far as the treatment of diabetes is concerned. Also, culture of islet cells has proved to be rather frustrating and difficult. No consistent techniques have been developed, and simplified methods for islet cell preparation and adequate sites for islet cell placement would allow for further progress in this area. Ultimately, rejection remains the greatest obstacle to success. We report a simplified technique for enriching dog pancreatic islet cells. This preparation was injected into the renal subcapsular space in both homograft (3 experiments) and heterograft (3 experiments) situations. After six weeks, nephrectomy was performed, and histochemical techniques demonstrated many groups of live islets in betweeen the tubules in the renal cortex. No acinar cells were observed. Blood samples from the renal artery and renal vein at the time of nephrectomy revealed an average 36.9 percent increase in insulin concentration in the renal veins, supporting an active secretory role of these transported islet cells. This technique points to (i) the possible role of a "renal factor" in promoting growth of islet cells and (ii) the feasibility of successful transplantation of enriched islet cells as a potential approach to the curative treatment of diabetes mellitus. (AU)

Absence of islet cell autoantibodies in Jamaican Blacks with diabetes mellitus

Forty-two patients, mainly of Black ancestry, attending the Diabetic Clinic, University Hospital of the West Indies, were studied for the frequency of autoantibodies against pancreatic islet cells (ICA), thyroid microsomes (TMA) and gastric parietal cells (PCA). There were 24 men and 18 women with an age range of 6-77 years and a mean age of 56.3 ñ 16.5 years. They had had diabetes for periods ranging from 1 to 40 years with a mean duration of 12.3 yearsñ 7.9 years. Sixty per cent had had insulin therapy for periods ranging from 0.25 to 25 years with a mean duration of 7.6 ñ 6.4 years. The mean body mass index was 24.0 ñ 2 with a range of 16.5 - 32.1. No patient had ICA. Of the insulin-treated patients, 17 percent were TMA positive. No patient had both TMA and PCA positivity. Amongst black populations, there is less evidence for autoimmune pathogenesis of insulin-requiring diabetes. The results suggest geographic as well as racial heterogeneity for black populations with diabetes, and emphasize the limitations of Caucasian Euro-American classifications of the disease, (AU)

Insulin release pattern after blockade of catecholamine synthesis with alpha-methyl tyrosine in vivo

Insulin release pattern in vivo was studied using 30 control rats and 30 rats treated with alpha-methyl tyrosine to block catecholamine synthesis in vivo four days before the time of investigation. The drug treated animals exhibited higher fasting insulin levels, and also the phase insulin release after the B cell was challenged with a glucose load was significantly higher in these animals than occurred in the controls. This observation implies that the B cell is modulated by the sympathetic nervous system in its function and the insulin release would vary according to the emotional state of the individual. (AU)

Preparation and some properties of isolated islets of langerhans from rabbit pancreas

Isolated islets of Langerhans have been prepared by collagenase digestion of rabbit pancreas. These islets are capable of responding with increased insulin secretion to high extracellular glucose concentrations, but show a relatively high "basal" secretion as compared to incubated pancreatic pieces of approximately 1 cm3 surface area. Insulin is not degraded in contact with islets. The cause of the apparently low insulin content per islet requires further investigation (AU)

Critical staining of pancreatic alpha granules with phosphotungstic acid hematoxylin

Mammalian pancreatic alpha granules were differentially stained with phosphotungstic acid haematoxylin. Paraffin sections were dewaxed and hydrated, oxidised 5-40 sec in freshly prepared 0.3 percent KMnO4 acidified with 0.3 percent (w/v) H2SO4, decolourised in 4 percent potassium metabisulphite, mordanted 20 min to 2 hr in 4 percent iron alum, stained in phosphotungstic acid haematoxylin 16-48 hr, rinsed in 95 percent ethanol until no stain runs from the tissue, dehydrated in absolute ethanol, cleared in xylene, and covered in synthetic resin. Advantages of this procedure are: (1) consistent, reproducible staining; (2) applicability to all the common laboratory mammals and man; (3) wide latitude at each stage, permitting its use as a routine method; and (4) superior visualization of alpha granules, due to suppression of background staining and absence of glare. For fixation, formalin-acetic or Bouin's solution is recommended (AU)