Kidney volume in type 1 (insulin-dependent) diabetic patients with normal or increased urinary albumin excretion: effect of long-term improved metabolic control

Bitter Melon (Momordica charantia L.) Fruit Bioactives Charantin and Vicine Potential for Diabetes Prophylaxis and Treatment

Natural products are gaining clinical significance in modern day health care systems to prevent diseases. Bitter melon, a health promoting vegetable, is traditionally used for medical nutrition therapy to cure diabetes but to reap maximum health claims, vigilant control of its substances in diet is crucial as part of curative action for effective diabetes management. In the present research, first phase focused on detection of key bioactive components, i.e., charantin and vicine in different parts of its fruit. In the second phase, normal and hyperglycemic Sprague Dawley rats were fed on skin, flesh and whole fruit of bitter melon at 150 and 300 mg/kg body weight and assessed for diabetes prophylaxis and treatment. The highest amount of charantin (0.16 ± 0.02 mg/g) was recorded in flesh while vicine was present in abundance in whole fruit (0.21 ± 0.01 μg/100 g). In normal rats, bitter melon supplementation was helpful in managing the onset of diabetes. Hyperglycemic rats showed diabetic complications including polydipsia, polyuria, glycosuria, renal hypertrophy and increased glomerular filtration rate. However, bitter melon consumption showed significant improvements in these parameters. The most potent dose was 300 mg/kg whole fruit that resulted in 31.64% lowering of blood glucose level and 27.35% increase in insulin level in hyperglycemic rats.

Structure, not just function

Although kidney size can be important in the evaluation of renal disease, it has not been carefully studied and true volume is rarely measured, and good normative data are lacking. Wang et al. measured both cortical and medullary volumes in potential transplant donors and correlate these with physiologic, morphometric, and metabolic parameters. The results reveal interesting and potentially important correlations and differential responses between the two compartments, providing a framework for future investigation.

Antioxidant, anti-diabetic and renal protective properties of Stevia rebaudiana

BACKGROUND

Stevia rebaudiana Bertoni has been used for the treatment of diabetes in, for example, Brazil, although a positive effect on antidiabetic and its complications has not been unequivocally demonstrated. This herb also has numerous therapeutic properties which have been proven safe and effective over hundreds of years. Streptozotocin is a potential source of oxidative stress that induces genotoxicity.

OBJECTIVE

We studied the effects of stevia leaves and its extracted polyphenols and fiber on streptozotocin induced diabetic rats. We hypothesize that supplementation of polyphenols extract from stevia to the diet causes a reduction in diabetes and its complications.

DESIGN/METHODS

Eighty Wistar rats were randomly divided into 8 groups; a standard control diet was supplemented with either stevia whole leaves powder (4.0%) or polyphenols or fiber extracted from stevia separately and fed for one month. Streptozotocin (60 mg/kg body weight, i.p) was injected to the diabetic groups on the 31st day. Several indices were analyzed to assess the modulation of the streptozotocin induced oxidative stress, toxicity and blood glucose levels by stevia.

RESULTS

The results showed a reduction of blood glucose, ALT and AST, and increment of insulin level in the stevia whole leaves powder and extracted polyphenols fed rats compared to control diabetic group. Its feeding also reduced the MDA concentration in liver and improved its antioxidant status through antioxidant enzymes. Glucose tolerance and insulin sensitivity were improved by their feeding. Streptozotocin was also found to induce kidney damage as evidenced by decreased glomerular filtration rate; this change was however alleviated in the stevia leaves and extracted polyphenol fed groups.

CONCLUSION

The results suggested that stevia leaves do have a significant role in alleviating liver and kidney damage in the STZ-diabetic rats besides its hypoglycemic effect. It might be adequate to conclude that stevia leaves could protect rats against streptozotocin induced diabetes, reduce the risk of oxidative stress and ameliorate liver and kidney damage.

Determinants and functional significance of renal parenchymal volume in adults

BACKGROUND AND OBJECTIVES

The significance of renal parenchymal volume and the factors that influence it are poorly understood.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Renal parenchymal volume (RPV) was measured on contrast-enhanced CT scans after exclusion of sinus fat and vessels in 224 healthy subjects evaluated as kidney donors and in a separate cohort of 22 severely obese individuals before and after 6 months of weight loss. GFR was measured by iohexol clearance in 76 of the transplant donors. RPV was correlated with age, GFR, and various anthropometric parameters.

RESULTS

In potential transplant donors, RPV correlated with body surface area (BSA; r = 0.68) and was 7% larger in men but did not vary with age or race. Gender and body size were independent determinants of RPV. RPV correlated well with GFR (r = 0.62) and accounted for almost all of the variability in a model of GFR that included age, race, gender, and body surface area. GFR correlated more strongly with RPV than with creatinine-based equations. The same relationship between RPV and BSA was observed in obesity, and RPV decreased with weight loss.

CONCLUSIONS

In healthy adults younger than 65 years, renal parenchymal volume is governed by body size and gender but not age or race and is strongly correlated with GFR. This indicates that renal parenchymal volume varies to meet metabolic demand and is closely linked to renal function.

Urinary transforming growth factor-beta(1), collagen IV and the effect of insulin in children at diagnosis of diabetes mellitus

OBJECTIVE

This study investigated whether metabolic derangement at diagnosis of diabetes mellitus affects the function of the basement membrane and the excretion of several components and whether insulin treatment can normalize this. It was designed to evaluate urinary excretion rates of transforming growth factor-beta(1) (TGF-beta(1)), the carboxy-terminal domain of collagen IV (NC1) and albumin in children during the first 20 days of treatment after diagnosis of type 1 diabetes.

MATERIAL AND METHODS

Thirty-four newly diagnosed diabetic children between 4 and 16 years of age and 26 healthy children of matching age were studied with timed overnight urine collections. Urine was collected during the first 20 days of treatment.

RESULTS

Urinary excretion of albumin and TGF-beta(1) in diabetic children were significantly increased at entry but normalized during 20 days of treatment with insulin compared with control children. In contrast, the non-significant high NC1 excretion at diagnosis did not change but became significantly increased after 20 days of insulin treatment. Overall, the kidney size was within normal limits and unaffected by treatment. The largest kidneys had less NC1 excretion (R= - 0.67, p<0.05, n=13) and a lower glomerular filtration rate (R= - 0.77, p<0.01, n=10) than the smallest kidneys. After 20 days of treatment TGF-beta(1) excretion had decreased in children with kidney size > 8.5 cm.

CONCLUSION

Correction of the metabolic derangement with insulin decreased excretion of albumin and TGF-beta(1), but had no effect on kidney size and urine NC1 excretion, presumably because the observation period was too short.

Effect of bitter gourd (Momordica charantia) on glycaemic status in streptozotocin induced diabetic rats

Bitter gourd (Momordica charantia), a commonly consumed vegetable is used as an adjunct in the management of diabetes mellitus. A study was carried out to examine the effect of edible portion of bitter gourd at 10% level in the diet in streptozotocin induced diabetic rats. To evaluate the glycaemic control of bitter gourd during diabetes, diet intake, gain in body weight, water intake, urine sugar, urine volume, glomerular filtration rate and fasting blood glucose profiles were monitored. Water consumption, urine volume and urine sugar were significantly higher in diabetic controls compared to normal rats and bitter gourd feeding alleviated this rise during diabetes by about 30%. Renal hypertrophy was higher in diabetic controls and bitter gourd supplementation, partially, but effectively prevented it (38%) during diabetes. Increased glomerular filtration rate in diabetes was significantly reduced (27%) by bitter gourd. An amelioration of about 30% in fasting blood glucose was observed with bitter gourd feeding in diabetic rats. These results clearly provided experimental evidence that dried bitter gourd powder in the diet at 10% level improved diabetic status signifying its beneficial effect during diabetes.

Widening of foot processes in normoalbuminuric adolescents with type 1 diabetes

We compared renal morphology in normoalbuminuric adolescents with type 1 diabetes with age-and sex-matched controls. Renal morphological measurements in 46 unselected adolescents with diabetes for approx. 10 years were compared with those in 20 healthy kidney donors. Renal volume estimated by ultra-sound, renal function determined by clearances of inulin and para-aminohippurate, and long-term mean HbA(1c) were measured in the patient group. Basement membrane thickness (BMT), mesangial matrix and capillary volume fractions per glomerulus [V(V)(matrix/glom), V(V)(cap/glom)] were significantly greater in patients than in controls (505 nm, 10.5%, 46.7% vs. 320 nm, 7.9% and 39.3%). The foot processes were wider in patients than in living donors (414 nm vs. 372 nm). There was no difference in mean kidney volume of patients with diabetes and healthy subjects. Glomerular filtration rate, body weight, and slit pore length density explained 60% of the variance in renal volume. After about 10 years' duration of type 1 diabetes, BMT, V(V)(matrix/glom), V(V)(cap/glom), and foot process width were greater in normoalbuminuric adolescents than in healthy controls. This increase in foot processes of normoalbuminuric patients has not been reported before.

Diabetic nephropathy is markedly enhanced in mice lacking the bradykinin B2 receptor

Type I human diabetics and streptozotocin-induced diabetic mice with higher genetically determined levels of angiotensin-converting enzyme have an increased risk of developing nephropathy. However, previous experiments in mice and computer simulations indicate that modest increases in angiotensin-converting enzyme have minimal effects on blood pressure and angiotensin II levels, although bradykinin decreases significantly, inferring that bradykinin is critical for protecting the kidney in diabetics. Here, we confirm this inference by demonstrating that Akita diabetic mice lacking the bradykinin B2 receptor develop overt albuminuria, excreting the equivalent of >550 mg/day albumin in humans, which contrasts with the microalbuminuria (equivalent to <150 mg/day) seen in their simply diabetic littermates. The overt albuminuria is accompanied by a marked increase in glomerular mesangial sclerosis. The importance of bradykinin demonstrated here bears strongly on how current drugs reduce diabetic nephropathy and suggests that B2 receptor-specific agonists merit consideration in this context.

Renal function before and long after liver transplantation in children

BACKGROUND

Renal dysfunction occurs in children with liver diseases and renal function is often further impaired after orthotopic liver transplantation (OLT). Inaccurate methods of determining renal function are used in many cases. We studied renal function with accurate methods before and repeatedly after OLT to analyze the effect of the underlying diseases, hypertension, and the immunosuppressive agents.

METHODS

A total of 46 children were studied both before and annually after OLT with clearances of inulin and paraaminohippuric acid to determine the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). The clearance of inulin was also compared with the formula creatinine clearance.

RESULTS

GFR and ERPF decreased from before to after OLT and decreased further during the first years after OLT. Patients with extrahepatic biliary atresia and with tumours showed higher GFR 1 year after OLT than those with metabolic and miscellaneous disorders. No significant change in GFR of individual patients occurred from the first to the last values determined at around 1 and 6 years after OLT. No difference in renal function was seen during the first years between patients treated with cyclosporine as compared to those treated with tacrolimus, but 4 years after OLT, the GFR was higher in the tacrolimus-treated patients. Patients on antihypertensive agents had lower GFR than the normotensive ones. There was no agreement between GFR, determined by clearance of inulin, and that calculated on the basis of serum creatinine and the height of the patients.

CONCLUSIONS

Renal function is reduced by OLT and decreases further during the first years after OLT. Patients with metabolic disorders and those on antihypertensive treatment have the lowest GFR. Determination of GFR by the formula creatinine clearance is inaccurate in children after liver transplantation.

Low birth weight and reduced renal volume in Aboriginal children

Low birth weight predisposes to renal disease in Aboriginal adults. This could be due to reduced nephron numbers, which might be reflected in lower kidney volumes, at least early in life. In this study we evaluated the association of birth weight with renal volume in 174 children and in adolescents 5 to 18 years old in an Aboriginal community with high rates of renal disease. Their mean birth weight was 2.9 kg, and 19% had been low birth weight (<2.5 kg). Kidney dimensions were measured by ultrasound by a single observer, and kidney volume (KV) was calculated from the formula KV (mL) = length x (depth 1 + depth 2)/2 x 0.523. Combined kidney volume, corrected for body surface area (corrKV), was independent of age and averaged 240 +/- 45 mL/1.73 m(2). The average corrKV was significantly lower (by about 20 mL) in low birth weight children than in those with "normal" birth weight. There was a difference of 32 mL in combined corrKV between children in the lowest versus the highest quintile of birth weight. Disparities in calculated kidney volume were driven more by lower kidney depth than length in low birth weight children. We conclude that low birth weight children have lower renal volumes than children of higher birth weights, after correction for current body size. This conclusion is compatible with the theory that intrauterine growth retardation is associated with reduced nephron endowment. The susceptibility to renal disease associated with low birth weight in this population might be mediated in part through this mechanism.

Intensive diabetes management decreases Na-Li countertransport in young subjects with type 1 diabetes and enlarged kidneys

In type 1 diabetes, increases in sodium-lithium countertransport (Na-Li CT), kidney volume (KV), and albumin excretion rate (AER) may precede the development of persistent microalbuminuria. Limited data exist on reversibility of these factors early in the evolution of diabetic nephropathy. A crossover design was used to study the separate effects of enalapril and intensive diabetes management (IDM) on Na-Li CT, KV and AER in 17 children and adolescents with type 1 diabetes (5-10 years duration) with large kidneys (>275 ml/1. 73 m(2)) and predominantly normoalbuminuria. Subjects were randomized to receive 3 months of either enalapril (0.25 mg/kg/day) or IDM, a 3-month washout, followed by the alternate treatment for 3 months. During IDM, HbA1c decreased 2.5% (pre 9.5+/-0.3% (mean+/-SE), post 7.0+/-0.1%, p<0.0001), but was unchanged while on enalapril (pre 8.8+/-0.3%, post 8.5+/-0.3%, p=0.1). A significant decrease in Na-Li CT was seen with IDM (pre 0.43+/-0.05, post 0.36+/-0.04 mmol/l RBC/h, p=0.006) but not angiotensin converting enzyme inhibition (ACE-i) (pre 0.39+/-0.04, post 0.38+/-0.04 mmol/RBC/h, p=0.4). Neither ACE-i nor IDM affected KV or AER. It is concerning that kidney enlargement does not appear reversible at this early stage in the pathogenesis of diabetic nephropathy, although our conclusions are limited by the short duration of intervention and small sample size. The reduction in Na-Li CT with IDM suggests this may be a potentially modifiable risk factor for diabetic nephropathy.

Microalbuminuria: pathogenesis, prognosis and management

The development in recent years of sensitive assays specific for albumin has facilitated extensive investigation of the pathophysiology and clinical significance of microalbuminuria. It is now clear that the appearance of microalbuminuria represents a crucial event in the natural histories of diabetes mellitus and essential hypertension. It reflects the presence of generalized vascular damage and is strongly predictive of subsequent renal failure, cardiovascular morbidity, and death. Therapeutic interventions, including strict diabetic and blood-pressure control, can reduce microalbuminuria and improve the overall prognosis. The detection and treatment of microalbuminuria in these high-risk groups should now form an integral part of their management. Large-scale screening programmes are also recommended for insulin-dependent diabetics.

Contributory roles of circulatory glucagon and growth hormone to increased renal haemodynamics in type 1 (insulin-dependent) diabetes mellitus

The stimulatory effects of growth hormone (GH) and glucagon on renal function are well known, but it is uncertain whether these hormones are involved in the increase in renal function, characteristic of type 1 (insulin-dependent) diabetes mellitus. Therefore, the circulatory levels of GH and glucagon were measured in 10 type 1 diabetic patients with an elevated glomerular filtration rate (GFR > 130 ml min-1 1.73 m-2) and in 20 age and sex matched normofiltering patients (GFR ranging from 90-130 ml min-1 1.73 m-2). In the patients, fasting glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were determined using 125I-iothalamate and 131I-hippuran, respectively, during near-normoglycaemia. On a separate day, the levels of glucagon and GH were determined in the fasting basal state and after exercise. Multiple regression analysis disclosed that GFR was positively correlated with HbA1 (r2 = 0.18, p < 0.01), glucagon (r2 = 0.14, p < 0.03) as well as exercise-stimulated GH (r2 = 0.10, p < 0.05). ERPF was independently associated with HbA1 (r2 = 0.24, p < 0.005) and glucagon (r2 = 0.18, p < 0.01), whereas renal vascular resistance (RVR) was negatively correlated with stimulated GH (r2 = 0.18, p < 0.02). Kidney volume was positively correlated with HbA1 (r2 = 0.26, p < 0.001) and inversely with RVR (r2 = 0.16, p < 0.01), but not with glucagon or stimulated GH. The present study suggests that circulatory GH and glucagon play a contributory role in the renal haemodynamic changes in type 1 diabetes mellitus.

Glomerular structural changes in type 1 (insulin-dependent) diabetes mellitus: causes, consequences, and prevention

Diabetic nephropathy is caused primarily by advanced glomerulopathy, the renal expression of diabetic microangiopathy. With stereological methods a quantitative description of the structural changes is achieved. The glomerulopathy is characterized by an increase in basement membrane material: thickening of the capillary wall and an increase in mesangial volume relative to glomerular volume, comprising increase in matrix. Among groups of patients conformity between renal function stage and structure exists. The parameters measuring glomerulopathy are normal at the onset of diabetes; patients with normoalbuminuria may show slight basement membrane thickening, or normal parameters; the microalbuminuric group shows a measurable, but moderate glomerulopathy; patients with overt nephropathy have advanced lesions; at this stage heterogeneity among glomeruli makes the estimates weaker. Recent data indicate that the changes in peripheral basement membrane and in mesangial matrix develop in concert and both contribute to the early stage of glomerulopathy in patients with microalbuminuria. As to the consequences of the structural changes the mechanism of albuminuria is not clear. It is suggested that the early glomerulopathy entails other structural modifications, including formation of new vessels which may be the site of leakage. The marked deviations in glomerular filtration rate correspond well with estimates of filtration surface area: in the early hyperfunction state it is increased; in advanced nephropathy it is decreased, due to advanced glomerulopathy in conjunction with glomerular occlusion. The diabetic state is the necessary condition for the glomerulopathy. In relating structural changes to presumed contributing causes no supporting evidence of a relationship with glomerular hyperfunction or hypertrophy was observed. The structural parameters may be useful tools in clinical trials aiming at arresting the development of glomerulopathy, and thereby providing a prevention of diabetic nephropathy.