Thiol group modulation of sodium-lithium countertransport kinetics in diabetic nephropathy

Abnormal erythrocyte sodium-lithium countertransport (Na-Li CT) activity, traditionally measured at a single sodium concentration of 140 mmol.l-1 (V140), may represent an inherited risk marker for diabetic nephropathy. The membrane defect underlying this association is poorly understood, though modulation by key protein thiol groups appears to be important in essential hypertension. To improve understanding of this abnormality, Na-Li CT kinetics in untreated erythrocytes and after thiol group alkylation with N-ethylmaleimide were investigated in 18 subjects with diabetic nephropathy, 20 normoalbuminuric insulin-dependent diabetic (IDDM) subjects and 18 non-diabetic individuals. Using the traditional assay, V140 was similar in subjects with diabetic nephropathy compared to IDDM control subjects vs 0.311 (0.152-0.475) (0.247 (0.111-0.498) mmol Li.h-1.l erythrocytes-1). Kinetic parameters were abnormal in subjects with diabetic nephropathy compared with diabetic and non-diabetic control subjects with both Vmax (maximal Na-Li CT activity) (0.454 (0.257-0.963) vs 0.338 (0.183-0.972) vs 0.332 (0.213-0.603) mmol Li.h-1.l erythrocytes-1, p < 0.05), and Vmax/Km(So) ratio, reflecting ion association (6.03 (2.3-9.6) vs 4.73 (2.0-10.4) vs 4.48 (1.5-7.1), p < 0.01), significantly higher. N-ethylmaleimide decreased K(m)(So) and Vmax abolishing differences in Vmax/Km(So) ratio between groups (2.45 (1.18-4.21) vs 2.23 (0.96-4.3) vs 2.44 (1.4-3.7), but enhancing the differences in Vmax (0.186 (0.090-0.315) vs 0.120 (0.051-0.256) vs 0.128 (0.080-0.206) mmol Li.h-1.l erythrocytes-1, p < 0.0001). Of subjects with diabetic nephropathy, 78% were outside the 75th percentile of the non-diabetic control subjects when Vmax and Vmax/Km(So) ratio were combined, compared to 20% of the normoalbuminuric control subjects. We conclude that the traditional assay, V140, is poor at detecting individuals with diabetic nephropathy. Study of the kinetic parameters of the transporter, including thiol group modulation, suggests that increased ion association, Vmax/Km(So) ratio may represent the inherited defect and improves identification of subjects with diabetic nephropathy.

Long-term follow-up of kidney donors: a longitudinal study

BACKGROUND

Kidney donors are not adversely affected by compensatory hyperfiltration of the remaining kidney in the early years after nephrectomy, but longterm longitudinal studies are lacking.

METHODS

The renal function and blood pressure of 75 donors was evaluated in 1984, 1.4-20.7 years after surgery. Forty-seven of the original cohort (23 male, age 38-80 years) underwent repeat study a decade later (12-31 years post-nephrectomy), using identical laboratory techniques.

RESULTS

Glomerular filtration rates (GFR) as measured by 51Cr EDTA clearance was relatively unchanged a decade later with 41 of 47 subjects (87%) having EDTA clearance within the normal laboratory reference range at review. The change in GFR in the remaining six subjects was statistically not significant. No correlation between GFR and time after nephrectomy was detected. Albumin excretion rate (AER), on timed overnight urine collections, was increased (> 20 micrograms/min) in 16 subjects (34%), although 14 of these individuals were also hypertensive. The prevalence of hypertension was significantly increased compared with age/sex matched data from epidemiological studies of the general population (both in the UK and the US), especially in those over the age of 55 years.

CONCLUSION

This study demonstrates that the function of the solitary kidney is not adversely affected by prolonged compensatory hyperfiltration, although there appears to be an increased prevalence of microalbuminuria and hypertension. Regular follow-up of kidney donors is recommended in order to manage their complications effectively and to detect hypertension and or renal impairment early in those who may develop it.

Cyclophosphamide in severe steroid-resistant bronchiolitis obliterans organizing pneumonia

A patient receiving carbamazepine and imipramine presented with severe bronchiolitis obliterans organizing pneumonia (BOOP). He developed progressive respiratory failure in spite of high-dose steroid treatment. Cyclophosphamide was given as adjunctive therapy, and a rapid improvement was seen. The authors suggest that an early therapeutic trial of cyclophosphamide should be considered in patients with BOOP who fail to respond to steroids.

Examination of two genetic polymorphisms within the renin-angiotensin system: no evidence for an association with nephropathy in IDDM

Premature cardiovascular disease is common in insulin-dependent diabetic (IDDM) patients who develop diabetic nephropathy. Genetic polymorphism within the renin-angiotensin system has been implicated in the aetiology of a number of cardiovascular disorders; these loci are therefore candidate genes for susceptibility to diabetic renal disease. We have examined the angiotensin converting enzyme insertion/deletion polymorphism and angiotensinogen methionine 235 threonine polymorphism in a large cohort of Caucasian patients with IDDM and diabetic nephropathy. Patients were classified as having nephropathy by the presence of persistent dipstick positive proteinuria (in the absence of other causes), retinopathy and hypertension (n = 242). Three groups were examined for comparison: ethnically matched non-diabetic subjects (n = 187); a geographically defined cohort of newly diagnosed diabetic patients (n = 341); and IDDM patients with long duration of disease (> 15 years) and no evidence of overt nephropathy (n = 166). No significant difference was seen in distribution of angiotensin converting enzyme or angiotensinogen genotypes between IDDM patients with nephropathy and recently diagnosed diabetic subjects (p = 0.282 and 0.584, respectively), nor the long-duration non-nephropathy diabetic subjects (p = 0.701 and 0.190, respectively). We conclude that these genetic loci are unlikely to influence susceptibility to diabetic nephropathy in IDDM in the United Kingdom.

Cortical blindness and cerebral infarction associated with severe hypoglycemia

OBJECTIVE

To describe a case of cortical blindness and cerebral infarction associated with severe hypoglycemia.

CONCLUSIONS

The possible pathogenesis of the neurological defects is discussed.

Effects of heparin on renal morphology and albuminuria in experimental diabetes

Female nondiabetic and streptozotocin diabetic Wistar rats received 200 units heparin two times daily by subcutaneous injection for 6 mo. Mesangial volume fraction was reduced in heparin-treated control (CH) compared with untreated control (C) animals (CH 0.18 +/- 0.02 vs. C 0.24 +/- 0.02, P < 0.05), but other histological parameters were similar. In the heparin-treated diabetic (DH) group, wet kidney weight was increased compared with the untreated diabetic (D) group (DH 1,156 +/- 39 vs. D 1,050 +/- 30 mg, P < 0.05), as were absolute, but not fractional, glomerular volume (P < 0.05) and capillary volume (P < 0.05). Basement membrane thickness (DH 193 +/- 3 vs. D 231 +/- 9 nm, P < 0.01) and mesangial/glomerular volume fraction (P < 0.001) were decreased. Urinary albumin excretion was increased in the heparin-treated control animals compared with control animals [CH 980 (range 150-4,448) vs. C 221 (range 86-654) micrograms/24 h, P < 0.001] and in the heparin-treated diabetic animals compared with the diabetic animals [DH 12,785 (range 4,495-29,520) vs. D 899 (range 450-1,335) micrograms/24 h, P < 0.001]. Thus the possibly deleterious increases in glomerular capillary volume and albumin excretion may negate the beneficial effects of heparin on mesangial and basement membrane structures.

Renal function in long-duration type I diabetes

OBJECTIVE

The development of persistent proteinuria is reported to be uncommon after 30 years of type I diabetes, and the significance of microalbuminuria in patients with long-duration diabetes is unclear. We therefore undertook to study, in detail, renal function in patients with long-duration type I diabetes.

RESEARCH DESIGN AND METHODS

We measured albumin excretion rate (AER), glomerular filtration rate (GFR), and serum creatinine in 140 patients with > or = 30 years of type I diabetes. We also assessed patients for other micro- macrovascular complications of diabetes together with factors implicated in the development of diabetic renal disease.

RESULTS

Of the patients, 23% had microalbuminuria (AER 20-200 micrograms/min and/or urinary albumin-to-creatinine ratio [ACR] > 2.5 mg/mmol [men] or > 3.5 mg/mmol [women] and dipstick negative for proteinuria), 4% had overt nephropathy (AER > 200 micrograms/min or persistent dipstick positive proteinuria), and 73% were normoalbuminuric (AER < 20 micrograms/min or ACR < 2.5 mg/mmol [men], < 3.5 mg/mmol [women]). Patients with microalbuminuria had lower GFR (81.5 +/- 30.2 vs. 96.0 +/- 20.3 ml.min-1.1.73 m-2; P = 0.06) and higher serum creatinine (104 +/- 32 vs. 92 +/- 16 mumol/l; P = 0.06) than those patients with normoalbuminuria. Both serum creatinine (P < 0.05) and tobacco consumption (P = 0.01) were significantly and independently related to elevated albumin excretion.

CONCLUSIONS

A substantial proportion of these patients have microalbuminuria and evidence of impaired renal function, suggesting that progression to end-stage renal failure may still be inevitable. Clinicians should continue to monitor renal function in these patients. The relationship between tobacco consumption and nephropathy also makes clear the need to reduce cigarette smoking in the diabetic population.

Renal enlargement and insulin-like growth factor-1 accumulation in the Wistar rat model of experimental diabetes is not prevented by angiotensin converting enzyme inhibition

Experimental diabetes is associated with renal enlargement and glomerular hyperfiltration. Possible mechanisms for these changes could be the direct effects of growth factors such as insulin-like growth factor-1 and angiotensin II. We investigated whether treatment with trandolapril, an angiotensin converting enzyme inhibitor, prevented renal enlargement in streptozotocin-diabetic rats. Seven groups of male Wistar rats were studied: C (control + placebo); CL (control + low-dose trandolapril, 0.01 mg.kg-1.day-1); CH (control + high-dose trandolapril, 0.5 mg.kg-1.day-1; DP (diabetic + placebo); DI (diabetic, insulin-treated); DL (diabetic + low-dose trandolapril); DH (diabetic + high-dose trandolapril) and DI (diabetic + insulin). From day 2 glucose concentrations and body weight were similar in the non-diabetic and diabetic animals treated with insulin. Diabetic animals treated with placebo and low-dose trandolapril weighed significantly less compared to the control group. The diabetic groups, not treated with insulin, showed marked hyperglycaemia throughout the study. Kidney weight was greater in the diabetic, non insulin-treated groups compared with the control and insulin-treated groups. After 24 h of diabetes, kidney insulin-like growth factor-1 content was significantly increased from baseline levels in groups DP, DL and DH but by 48 h these levels had returned to normal. Renal tissue angiotensin converting enzyme activity was similar in groups C and DI but significantly reduced in all trandolapril-treated animals. Despite inhibiting renal angiotensin converting enzyme activity renal enlargement with increased tissue insulin-like growth factor-1 still occurred. This suggests that neither angiotensin II nor glomerular hyperfiltration, with raised intraglomerular pressure, play a role in the initial renal enlargement seen in experimental diabetes. Renal accumulation of insulin-like growth factor-1 appears to be an important factor in early renal hypertrophy and its effects are not modulated by angiotensin converting enzyme or angiotensin II.

Albumin excretion and vascular deaths in NIDDM

Non-insulin-dependent diabetes mellitus (NIDDM) is associated with premature mortality, generally thought to be exaggerated in patients with microalbuminuria. This prospective 8-year follow-up study aimed to determine outcome, mortality and cause of death in NIDDM patients with abnormal urinary albumin excretion compared to those with normal albumin excretion. We recruited 153 NIDDM patients with abnormal urinary albumin excretion and 153 control subjects with albumin excretion within the normal non-diabetic range, matched for age, sex and duration of diabetes, from three University hospital diabetic clinics in Newcastle upon Tyne. The outcome measures were status at follow-up, mortality and cause of death. Subjects with abnormal albumin excretion had a significantly higher 8-year mortality than matched control subjects (Odds Ratio 1.47, p = 0.02; 108 vs 66 per 1000 person years follow-up, p < 0.001). This difference was seen at all levels of abnormal albumin excretion, from just outside the normal range (10.6-29.9 microgram/min: 104 vs 61 per 1000 person years follow-up, p < 0.001) to more conventional definitions of microalbuminuria (> or = 30 micrograms/min: 111 vs 71 per 1000 person years follow-up, p < 0.01). Those with abnormal albumin excretion had an excess of vascular deaths compared to matched control subjects (Odds Ratio 1.70, p = 0.009), again at different levels of albumin excretion (10.6-29.9 micrograms/min p < 0.01, 30-150 micrograms/min p < 0.05). On multivariate analysis, age, initial ischaemic heart disease and initial albumin excretion rates were independent predictors of death from all causes.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydroxyproline excretion is increased in diabetes mellitus and related to the presence of microalbuminuria

Increased fracture frequency and low bone mass have each been reported in patients with diabetes. To see if these were related to increased bone resorption we have measured the urinary excretion of hydroxyproline in 73 patients with Type 1 (insulin-dependent) diabetes, 67 patients with Type 2 (non-insulin-dependent) diabetes, and 75 control subjects. Hydroxyproline excretion was increased in both types of diabetes: Type 1: 21 (10-36) (median (IQR) mumol mmol creatinine-1; Type 2: 25 (13-43) mumol mmol creatinine-1; control: 10 (6-22) mumol mmol creatinine-1 (p < 0.0001 and < 0.0002, respectively). Hydroxyproline excretion was not related to age, duration of diabetes or blood glucose control. Neither was it different in patients with or without retinopathy, neuropathy and macrovascular disease. However it was higher in patients with microalbuminuria at 35 (20-53) mumol mmol creatinine-1 than in those with normal protein excretion (25(13-37) mumol mmol creatinine-1 p = 0.03) or those with established proteinuria (18(8-26) mumol mmol creatinine-1 p = 0.001). We conclude that there is evidence of increased bone resorption in diabetes and that this is related to alterations in renal function.

Effects of growth hormone and thyroxine on kidney insulin-like growth factor-I and renal growth in hypophysectomized rats

The effects of treatment for 11 days with human growth hormone (hGH; 140 micrograms/day), thyroxine (T4; micrograms/day) and hGH+T4 on renal growth and content of insulin-like growth factor-I (IGF-I) in hypophysectomized rats have been compared with saline-treated hypophysectomized animals and intact control animals. Right kidney weight and kidney weight/body weight ratio remained low in the saline-treated group (313 +/- 9 mg vs 694 +/- 28 mg in controls on day 11, P < 0.001 and 3.4 +/- 0.12 x 10(-3) vs 4.2 +/- 0.10 x 10(-3), P < 0.005 respectively). In T4- and hGH-treated animals, kidney weight gain was similar (to 420 +/- 14 and 450 +/- 22 mg on day 11 respectively, P > 0.05), whilst the increase was greater in the group given hGH+T4 (to 572 +/- 34 mg, P < 0.001 compared with hGH- and T4-treated groups). The kidney weight/body weight ratio became normal in the T4- and hGH+T4-treated animals but remained low in the hGH-treated group. The renal content of IGF-I was low in the saline-treated animals throughout the study (92 +/- 10 ng/g on day 11 vs 219 +/- 8 ng/g in control animals, P < 0.001), but increased to a maximum of 88% above baseline on day 1 in the group given T4.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian variation of blood pressure in patients with diabetic nephropathy

The association between diurnal blood pressure variation and diabetic nephropathy was assessed in four groups of Type 1 (insulin-dependent) diabetic patients who underwent 24-h ambulatory blood pressure monitoring using an oscillometric technique. Patients with nephropathy, who had never been treated for hypertension (group D3, n = 13), were individually matched for age, sex and diabetes duration to a group of microalbuminuric patients (D2, n = 26), to normoalbuminuric patients (D1, n = 26) and to healthy control subjects (C, n = 26). Group D3 was also compared to patients with advanced nephropathy receiving treatment for hypertension, mainly a combination of angiotensin converting enzyme inhibitors, metoprolol and diuretics (D4, n = 11). In group D3 24-h diastolic blood pressure (85 +/- 8 mm Hg) was comparable to the results obtained in D4 (85 +/- 8 mm Hg) but significantly higher than in D2 (78 +/- 7 mm Hg), D1 (73 +/- 7 mm Hg) and C (73 +/- 7 mm Hg, p < 0.05, Tukey's test). The night/day ratio of diastolic blood pressure was higher in D3 (86 +/- 5%) and D2 (85 +/- 7%) than in C (80 +/- 7%, p < 0.02). This ratio was also elevated in group D4 (94 +/- 8%) compared to D3 (p < 0.05) corresponding to a marked smoothing of the diurnal blood pressure curve. The 24-h heart rate (beats per min) was significantly elevated in D3 (84 +/- 8) and D2 (80 +/- 10) compared with C (73 +/- 11, p < 0.05 Tukey's test), suggesting the presence of parasympathetic neuropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like growth factor I in initial renal hypertrophy in potassium-depleted rats

We investigated insulin-like growth factor I (IGF-I) in the kidney during the initial renal enlargement induced by dietary K depletion in rats. Kidney weight increase was significant after 3 days of K depletion and amounted to 29% after 7 days compared with pair-fed controls [839 +/- 34 vs. 648 +/- 17 mg (SE), P less than 0.01]. The kidney growth occurred despite almost complete arrest in body weight gain in K-depleted animals (8 +/- 3 vs. 34 +/- 4 g/7 days in controls, P less than 0.01). Whole kidney protein, RNA, and DNA estimations indicated that cellular hypertrophy during the first 4 days was followed by hyperplasia. Immunoassayable kidney IGF-I concentration increased by 106% (673 +/- 30 vs. 327 +/- 14 ng/g, P less than 0.01) in K-depleted animals 24 h after induction of K depletion, stayed elevated until day 4, and returned to control levels on day 7. After K depletion for 24 h, IGF-I immunostaining was markedly increased in the medullary parts of the collecting ducts from K-depleted animals, whereas kidney IGF-I gene expression (IGF-I mRNA) had decreased by 36%. The increase in total kidney IGF-I concentration and immunostainable IGF-I in collecting ducts in kidneys from K-depleted rats precedes the renal hypertrophy and thereby suggests a renotropic role for IGF-I. The increase in kidney IGF-I concentration is not associated with increased IGF-I mRNA levels, indicating that non-transcriptional mechanisms may be responsible for the renal IGF-I accumulation.

Octreotide administration in diabetic rats: effects on renal hypertrophy and urinary albumin excretion

Initial renal hypertrophy in experimental diabetes is prevented by administration of a long-acting somatostatin analogue octreotide (SMS). To investigate the long-term effects of SMS on renal hypertrophy and urinary albumin excretion (UAE), streptozotocin-diabetic and non-diabetic rats were treated with two daily subcutaneous injections of SMS (100 micrograms x 2) for six months. Untreated diabetic and non-diabetic animals were used as reference groups. No differences were seen between the two diabetic groups in respect to body weight, food intake, blood glucose levels, urinary glucose output, hemoglobin A1C(HbA1C), fructosamine, serum growth hormone (rGH) or creatinine clearance, but kidney weight (896 +/- 36 vs. 1000 +/- 24 mg, P less than 0.02), UAE (417 +/- 131 vs. 1098 +/- 187 micrograms/24 hr, P less than 0.02), kidney insulin-like growth factor I (IGF-I) (167 +/- 16 vs. 239 +/- 17 ng/g, P less than 0.01) and serum IGF-I (301 +/- 26 vs. 407 +/- 17 micrograms/liter, P less than 0.01) were all reduced in the SMS-treated diabetic animals when compared to the untreated diabetic group. In non-diabetic rats SMS reduced body weight (274 +/- 3 vs. 293 +/- 5 g, P less than 0.01), kidney weight (695 +/- 9 vs. 764 +/- 17 mg, P less than 0.01), UAE (83 +/- 29 vs. 364 +/- 114 micrograms/24 hr, P less than 0.02), kidney IGF-I (202 +/- 12 vs. 280 +/- 12 ng/g, P less than 0.01), serum IGF-I (428 +/- 21 vs. 601 +/- 54 micrograms/liter, P less than 0.01) and serum rGH (67 +/- 6 vs. 126 +/- 27 micrograms/liter, P less than 0.05) when compared to untreated controls. When kidney weights were expressed in relation to body weight no difference was found between SMS-treated and untreated controls, while the difference between SMS-treated and untreated diabetic animals was still present (P less than 0.01). In conclusion, chronic administration of SMS has abating effects on diabetic renal hypertrophy and UAE, and thus indicates that SMS may reduce development of diabetic kidney lesions in experimental diabetes. The long-term suppressive effects of SMS on renal enlargement and UAE may in part be mediated through reduction in circulating and kidney IGF-I levels.

Micral-test strips evaluated for screening for albuminuria

We have evaluated Micral-Test, an immunochemical strip test specific for albumin, as a screening tool for slight ("micro") albuminuria. First morning urine samples containing albumin concentrations (by radioimmunoassay) of 0.4-440 mg/L were collected from 112 diabetic patients. The Micral-Test result for each sample was assessed by one observer. All 34 samples having albumin concentrations greater than or equal to 20 mg/L and 71 of 78 samples less than 20 mg/L were correctly identified, giving 100% sensitivity and 91% specificity. Six samples were measured 10 times by one observer: three samples were read consistently; one, albumin concentration 86 mg/L, was read as 50 and 100 mg/L; and two, albumin concentrations 32 and 38 mg/L, were read as 20 and 50 mg/L, respectively. Contact with urine for 2 s rather than the recommended 5 s resulted in an underestimation of the albumin concentration in 13 of 35 samples (Z = -3.18, P = 0.001), as did taking readings earlier than the recommended 5 min (Z = -3.92, P less than 0.001). Six observers independently performed Micral-Test measurements on 10 samples. Eight samples were correctly classified as greater than or equal to 20 or less than 20 mg/L by all observers, but two (albumin concentrations 25 and 18 mg/L) were misclassified by at least one observer. The Micral-Test is a sensitive and specific screening tool, but is semiquantitative and critically time dependent.

Micral-Test Strips Evaluated for Screening for Albuminuria

We have evaluated Micral-Test, an immunochemical strip test specific for albumin, as a screening tool for slight ("micro") albuminuria. First morning urine samples containing albumin concentrations (by radioimmunoassay) of 0.4-440 mg/L were collected from 112 diabetic patients. The Micral-Test result for each sample was assessed by one observer. All 34 samples having albumin concentrations greater than or equal to 20 mg/L and 71 of 78 samples less than 20 mg/L were correctly identified, giving 100% sensitivity and 91% specificity. Six samples were measured 10 times by one observer: three samples were read consistently; one, albumin concentration 86 mg/L, was read as 50 and 100 mg/L; and two, albumin concentrations 32 and 38 mg/L, were read as 20 and 50 mg/L, respectively. Contact with urine for 2 s rather than the recommended 5 s resulted in an underestimation of the albumin concentration in 13 of 35 samples (Z = -3.18, P = 0.001), as did taking readings earlier than the recommended 5 min (Z = -3.92, P less than 0.001). Six observers independently performed Micral-Test measurements on 10 samples. Eight samples were correctly classified as greater than or equal to 20 or less than 20 mg/L by all observers, but two (albumin concentrations 25 and 18 mg/L) were misclassified by at least one observer. The Micral-Test is a sensitive and specific screening tool, but is semiquantitative and critically time dependent.

Screening for microalbuminuria: which measurement?

It now seems worth while to identify Type 1 diabetic patients with microalbuminuria, as improved blood glucose control and reduction of arterial blood pressure will slow if not prevent the progression to persistent proteinuria. Measurement of albumin excretion rate (AER) in a timed urine sample remains the gold standard for the definition of microalbuminuria, but is not a practical screening procedure. Thus attempts have been made to relate the albumin concentration of albumin:creatinine ratio in random or first morning urine samples to AER. There is a weak correlation of albumin concentration (r = 0.32 to 0.68) and albumin:creatinine ratio (r = 0.43 to 0.54) in a random urine sample with AER, and low sensitivity and specificity of a variety of different albumin concentrations and albumin:creatinine ratios to predict microalbuminuria. The correlation of albumin concentration (r = 0.86 to 0.90) and albumin:creatinine ratio (r = 0.74 to 0.91) in an early morning urine sample with AER is stronger. Measurement of albumin:creatinine ratio in an early morning urine sample appears to be the most reliable method of screening for microalbuminuria, with sensitivity of 88 to 100% and specificity 81 to 100% depending on the cut-off ratio chosen and the definition of microalbuminuria used. If the albumin:creatinine ratio in an early morning urine sample is less than or equal to 3.5 mg mmol-1, the patient can be classed as normoalbuminuric and re-screened annually. If the ratio is greater than or equal to 10.0 mg mmol-1, confirmation of microalbuminuria should be sought in a timed urine collection and appropriate therapy begun.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal insulin-like growth factor I and growth hormone receptor binding in experimental diabetes and after unilateral nephrectomy in the rat

We have measured specific binding of insulin-like growth factor I and growth hormone to renal plasma membranes from control, streptozotocin-diabetic, insulin-treated diabetic, uninephrectomised and combined diabetic-uninephrectomised male Wistar rats. Control, insulin-treated and uninephrectomised rats had similar body weights after 7 days (243 +/- 2 g), whereas diabetic and diabetic-uninephrectomised animals were significantly lighter (219 +/- 4 and 203 +/- 4 g, p less than 0.05). Blood glucose concentrations were similar in the diabetic and diabetic-uninephrectomised animals (around 26 mmol/l) but significantly lower in the insulin-treated group. Right kidney weight increased by 14% in the control, insulin-treated and sham-nephrectomised animals, by 33% in the diabetic group, 38% in thenephrectomised animals and 60% in the diabetic-nephrectomised group. The renal content of insulin-like growth factor I was similar and stable in the control, insulin-treated and sham-nephrectomised animals (208 +/- 14 ng/g wet weight) but rose to a peak of 669 +/- 35 ng/g in the diabetic group (p less than 0.001), 871 +/- 34 ng/g in the nephrectomised animals (p less than 0.001) and 1012 +/- 43 ng/g in the diabetic-uninephrectomised group (p less than 0.001). Maximum binding of insulin-like growth factor I fell on day 1 in the diabetic group (8.3 +/- 1.4 vs 5.2 +/- 0.71 x 10(-11) mol/l; p less than 0.01) but thereafter was identical to control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Microvascular complications of NIDDM in Hispanics and non-Hispanic whites. San Luis Valley Diabetes Study

The goal of this article was to examine the differences in the rates of microvascular complications of non-insulin-dependent diabetes mellitus (NIDDM) in Hispanic and non-Hispanic white subjects. This was a geographically based case-control study where prevalent cases of NIDDM were identified in medical records. Subjects attended a 4-h clinic to confirm NIDDM diagnosis and assess complication end points. Retinopathy was defined by stereofundus photographs. Distal symmetric neuropathy was determined by standardized clinical examination. Nephropathy was indicated by serum creatinine level, urine protein-creatinine ratio, and urine albumin concentration. This study consisted of 279 NIDDM subjects confirmed by oral glucose tolerance test and World Health Organization criteria aged 20-74 yr (187 Hispanic and 92 non-Hispanic white subjects). Duration-adjusted prevalence of retinopathy was significantly higher in non-Hispanic white subjects (54.1 per 100, 95% confidence interval [CI] 44.4-63.7) than in Hispanics (41.8 per 100, 95% CI 34.8-48.8). This excess occurred only in non-Hispanic white subjects with background retinopathy but not in those with more severe retinopathy. Hispanics and non-Hispanic white subjects did not differ significantly for the prevalence of neuropathy (31.6 per 100 in non-Hispanic white subjects and 26.3 per 100 in Hispanics) or nephropathy by any measure. There were no significant differences in duration of diabetes or mean glycohemoglobin levels between ethnic groups. Microvascular complications of NIDDM are not in excess among Colorado Hispanics, and retinopathy may be somewhat more common in non-Hispanic white people.

The effect of bromhexine on albumin excretion in insulin dependent diabetes

The effect of the mucolytic agent bromhexine, 72 mg daily for one month, on albumin excretion in insulin dependent diabetes was investigated in a double-blind, randomised, cross-over, placebo-controlled study. Nine patients with normal albumin excretion [overnight albumin excretion rate 3.2 (2.1-8.8) micrograms/min.; mean (range)], six with microalbuminuria [36 (22-95) micrograms/min.] and six with macroalbuminuria [321 (201-1215) micrograms/min.] participated. Albumin excretion was similar after treatment with bromhexine and placebo in all 3 groups [normoalbuminurics 3.6 (1.7-13.5) versus 3.3 (1.9-13.2) micrograms/min.; microalbuminurics 40 (20-128) versus 37 (20-103); macroalbuminurics 396 (247-2160) versus 443 (292-2592)]. Excretion of beta 2-microglobulin and creatinine clearance were identical at the end of each treatment. Blood glucose control and blood pressure remained constant throughout the study in the 3 groups. We conclude that bromhexine 72 mg daily for 1 month had no effect on albumin excretion in IDDM patients with normal and pathological albuminuria.

Inhibitory effect of octreotide on growth hormone-induced IGF-I generation and organ growth in hypophysectomized rats

We investigated the effect of a somatostatin analogue octreotide (SMS) on the stimulatory effect of recombinant human growth hormone (hGH) on insulin-like growth factor I (IGF-I) generation and growth in hypophysectomized rats. Two weeks after hypophysectomy, treatment was given for 11 days with either saline, SMS (100 micrograms/day), hGH (140 micrograms/day), or hGH plus SMS. Compared with saline-injected controls, hGH stimulated body weight gain [1.1 +/- 0.7 vs. 40.9 +/- 0.8 (SE) g, P less than 0.001] and width of epiphysial cartilage (138.0 +/- 4.5 vs. 356 +/- 3.8 microns, P less than 0.001). Combined treatment with hGH and SMS significantly reduced both body weight gain (29.1 +/- 2.5 g, P less than 0.001) and width of epiphysial cartilage (315.3 +/- 5.8 microns, P less than 0.001) compared with the effects of hGH alone. During 11 days of hGH treatment, serum IGF-I increased from 22 +/- 5 to 1,288 +/- 92 micrograms/l (P less than 0.001) but increased only 40% (513 +/- 71 vs. 1,288 +/- 92 micrograms/l, P less than 0.001) when SMS was given in combination with hGH. In gastrocnemius muscle, heart, and lung, but not in liver, kidney, and brain, SMS suppressed organ weight increase when given both with and without hGH substitution. Thymus and gastrointestinal tract weight were significantly reduced in the group receiving SMS alone and tended to be reduced in the hGH-substituted group given SMS as well. Tissue IGF-I was increased in liver, lung, kidney, and heart with hGH treatment (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like growth factor 1 and renal growth following ureteral obstruction in the rat

The role of insulin-like growth factor 1 (IGF-1) in renal growth of obstructed and contralateral kidneys was investigated for 10 days following unilateral ureteric obstruction in male Wistar rats. The weight of the obstructed kidney increased rapidly, rising from 671 +/- 10 to 1,378 +/- 42 mg on day 10, an increase of 105%. IGF-1 content of the obstructed kidney was significantly less than in control kidneys from day 2 onwards, reaching a nadir of 70 ng/mg, a fall of 64%. The protein concentration, expressed as milligrams per gram kidney weight, also fell rapidly from 141 +/- 11 to 88 +/- 3 mg/g on day 6. The weight of the contralateral kidney increased by 32%, from 671 +/- 10 to 887 +/- 48 mg on day 10. The IGF-1 content of this kidney was increased by 48% from baseline on day 1 (268 +/- 23 vs. 191 +/- 13 ng/g) and remained increased compared to sham-operated animals on days 6 and 8. The protein content, expressed as milligrams per gram kidney weight, remained constant throughout the study. We conclude that in the acutely obstructed left kidney increasing kidney weight is associated with falling concentration of IGF-1 and protein and may be due to oedematous and reactive change. Growth of the contralateral kidney is preceded by a rise in the concentration of IGF-1 and may represent true renal compensatory growth.