Z-2 microsatellite allele is linked to increased expression of the aldose reductase gene in diabetic nephropathy.

Epidemiological studies support the hypothesis that genetic factors modulate the risk for diabetic nephropathy (DN). Aldose reductase (ALDR1), the rate-limiting enzyme in the polyol pathway, is a potential candidate gene. The present study explores the hypothesis that polymorphisms of the (A-C)n dinucleotide repeat sequence, located 2.1 kb upstream of the transcription start site, modulate ALDR1 gene expression and the risk for DN. We conducted studies at two different institutions, the University of New Mexico Health Sciences Center (UNMHSC), and the Istituto Scientifico H San Raffaele (HSR). There were four groups of volunteers at UNMHSC: group I, normal subjects; group II, patients with insulin-dependent diabetes mellitus (IDDM) without DN; group III, IDDM with DN; and group IV, nondiabetics with kidney disease. At HSR we studied volunteers in groups I, II, and III. ALDR1 genotype was assessed by PCR and fluorescent sequencing of the (A-C)n repeat locus, and ALDR1 messenger ribonucleic acid (mRNA) was measured by ribonuclease protection assay in peripheral blood mononuclear cells. At UNMHSC we identified 10 alleles ranging from Z-10 to Z+8. The prevalence of the Z-2 allele among IDDM patients was increased in those with DN. Sixty percent of group III and 22% of group II were homozygous for Z-2. Moreover, 90% and 67% of groups III and II, respectively, had 1 or more copy of Z-2. In contrast, among nondiabetics, 19% of group IV and 3% of group I were homozygous for Z-2, and 69% and 32%, respectively, had 1 copy or more of Z-2. Among diabetics, homozygosity for the Z-2 allele was associated with renal disease [odds ratio (OR), 5.25; 95% confidence interval, 1.71-17.98; P = 0.005]. ALDR1 mRNA levels were higher in patients with DN (group III; 0.113 +/- 0.050) than in group I (0.068 +/- 0.025), group II (0.042 +/- 0.020), or group IV (0.015 +/- 0.011; P < 0.01). Among diabetics, ALDR1 mRNA levels were higher in Z-2 homozygotes (0.098 +/- 0.06) and Z-2 heterozygotes (0.080 +/- 0.04) than in patients with no Z-2 allele (0.043 +/- 0.02; P < 0.05). In contrast, among nondiabetics, ALDR1 mRNA levels in Z-2 homozygotes (0.034 +/- 0.04) and Z-2 heterozygotes (0.038 +/- 0.03) were similar to levels in patients without a Z-2 allele (0.047 +/- 0.03; P = NS). At HSR we identified eight alleles ranging from Z- 12 to Z+2. The prevalence of the Z-2 allele was higher in group III than in group II. In group III, 43% of the patients were homozygous for Z-2, and 81% had one copy or more of the Z-2 allele. In contrast, in group II, 4% were homozygous for Z-2, and 36% had one copy or more of the Z-2 allele. IDDM patients homozygous for Z-2 had an increased risk for DN compared with those lacking the Z-2 allele (OR, 18; 95% confidence interval, 2-159). IDDM patients who had one copy or more of Z-2 had increased risk (OR, 7.5; 95% confidence interval, 1.9-29.4) for DN compared with those without the Z-2 allele. These results support our hypothesis that environmental-genetic interactions modulate the risk for DN. Specifically, the Z 2 allele, in the presence of diabetes and/or hyperglycemia, is associated with increased ALDR1 expression. This interaction may explain the observed association between the Z-2 allele and DN.

A commentary on 10 years of aldose reductase inhibition for limited joint mobility in diabetes.

This investigation examines the clinical response to long-term treatment of the diabetic syndrome of limited joint mobility (LJM) using an aldose reductase inhibitor (ARI) in comparison to historical controls, and proposes a potential role of aldose reductase (AR) genotype and expression in the clinical response to ARI. Clinical parameters, including quantitative hand movement and electromyogram, were followed over a decade of continuous ARI treatment with sorbinil (400 mg/day) in two patients with insulin-dependent diabetes mellitus (IDDM) and severe compromising LJM, and compared to the published 10-year prospective investigation of untreated IDDM diabetic patients with LJM. Both subjects were homozygous for the Z-2 AR allele (A-C)23 that has been linked with microvascular complications of DM. Cellular AR mRNA/beta-actin ratios for both treated patients while on ARI therapy were approximately one-half the value observed in untreated patients with the complications of nephropathy or neuropathy. This is the longest reported experience of ARI intervention for any diabetic complication, documenting sustained correction of LJM, lack of side effects, and a potential molecular basis for the therapeutic response.

Corticosteroid responsive tenosynovitis is a common pathway for limited joint mobility in the diabetic hand.

OBJECTIVE: To test the hypothesis that diabetic tenosynovitis participates in the contractures of the syndrome of limited joint mobility (SLJM). METHODS: Adults with diabetes mellitus were referred for the evaluation of diabetic hand conditions. Patients with SLJM or diabetic trigger finger were studied after Dupuytren's contracture, hand neuropathy, carpal tunnel syndrome, and arthritis were excluded. A time series design was employed in which patients were observed for 3 mo to obtain a baseline, then the planar flexor tendon sheaths were injected with 10 mg of methylprednisolone acetate or 10 mg triamcinolone acetonide and were reassessed at 1, 3, and 12 mo. RESULTS: Response rates, defined by complete resolution of digital contractures and triggering after corticosteroid injection, were 94% (31/33), 76% 28/33), and 61% (17/29) at 1, 3, and 12 mo, respectively, which were all significantly different from preinjection (p < 0.001). Individual response rates for SLJM and trigger finger were similar. No appreciable differences between methylprednisolone acetate and triamcinolone acetonide were observed, although there was a trend for earlier recurrence with methylprednisolone. CONCLUSION: Corticosteroid injection is a safe and effective therapy that should be considered in patients with SLJM or diabetic trigger finger. The excellent response to injection indicates that diabetic tenosynovitis is a common pathway in diabetic hand conditions.

Catheter survival during long-term insulin therapy with an implanted programmable pump. The Implantable Insulin Pump Trial Study Group.

OBJECTIVE: To survey catheter complications and to analyze catheter survival during long-term intraperitoneal and intravenous insulin therapy with an implanted programmable pump with a sideport. RESEARCH DESIGN AND METHODS: Catheter occlusions were documented by measuring dynamic catheter resistance. Catheter migrations or breaks were demonstrated by X ray. When flushing the catheter with buffer solution through the sideport failed to clear the occlusion, catheters were replaced or laparoscopy was performed for the excision of fibrous tissue growth. Broken or migrated catheters were replaced. RESULTS: Occlusions were the most common catheter complications, and the majority of them (79% intraperitoneal and 84% intravenous) were cleared by flushing the catheter. Survival at 3 years was significantly higher for intraperitoneal catheters compared with intravenous catheters (60% intraperitoneal and 22% intravenous). CONCLUSIONS: Nonsurgical management of catheter occlusions contributed to extend catheter lifetime. Intraperitoneal catheters have a lower morbidity and a higher survival than intravenous catheters.

Idiopathic hypogonadotropic hypogonadism in a male runner is reversed by clomiphene citrate.

OBJECTIVE: To assess the efficacy of estrogen antagonist therapy on the function of the hypothalamic-pituitary-testicular axis in a young male runner with significant morbidity attributable to idiopathic hypogonadotropic hypogonadism. DESIGN: An uncontrolled case study. SETTING: The outpatient endocrinology clinic of a university tertiary referral center. PATIENT(S): A 29-year-old male who has run 50 to 90 miles per week since 15 years of age and who presented with a pelvic stress fracture, markedly decreased bone mineral density, and symptomatic hypogonadotropic hypogonadism. INTERVENTION(S): Clomiphene citrate (CC) at doses up to 50 mg two times per day over a 5-month period. MAIN OUTCOME MEASURE(S): Serum concentrations of LH, FSH, and T before and after CC therapy, as well as clinical indicators of gonadal function. RESULT(S): Barely detectable levels of LH and FSH associated with hypogonadal levels of T were restored to the normal range with CC therapy. The patient experienced improved erectile function, increased testicular size and sexual hair growth, and an improved sense of well being. CONCLUSION(S): Exercise-induced hypogonadotropic hypogonadism exists as a clinical entity among male endurance athletes, and CC may provide a safe and effective treatment option for males with debilitating hypogonadism related to endurance exercise.

Use of an integrated sideport for diagnosis and management of decreased flow rates in a programmable implanted insulin delivery system. Implantable Insulin Pump Trial Study Group.

The aim of this study was to develop procedures for the diagnosis and nonsurgical management of decreased insulin flow in an implantable programmable pump for long-term intraperitoneal or intravenous insulin delivery featuring a sideport. Patency of the catheter lumen was tested by measuring the time needed for sideport pressure to decrease by 50% after the injection of 0.1 ml of buffer solution. Pumping unit performances were assessed by measuring the volume of pump pulses after diverting the pump flow at the sideport. A catheter flush with buffer solution through the sideport was effective in clearing 79% of intraperitoneal and 84% of intravenous catheter occlusions. Washing the pumping unit with an alkaline solution after diverting pump flow at the sideport was effective in dissolving insulin aggregates inside the pumping unit and in restoring normal pump flow. These procedures were associated with a 1.3% rate of hypoglycemic episodes.

Insulin resistance limits glucose utilization and exercise tolerance in myophosphorylase deficiency and NIDDM.

Myophosphorylase deficiency [McArdle's disease (MD)] produces a defect in muscle glycogenolysis in which muscular work is limited by delivery of external sources of substrate, primarily glucose and nonesterified fatty acids, to meet energy demands associated with exercise. In the present study, we evaluated an unusual patient with both MD and non-insulin-dependent diabetes mellitus. We hypothesized that insulin resistance would limit transport of extracellular glucose to skeletal muscle during exercise, resulting in impaired exercise performance that was reversible by insulin infusion. The effect of a hyperinsulinemic "euglycemic" clamp on exercise tolerance was evaluated by in vivo 31P-magnetic resonance spectroscopy as well as total work performed. We observed that insulin infusion significantly increased the rate of systemic glucose utilization (P < 0.01) and also significantly decreased the ratio of inorganic phosphate to phosphocreatine (P < 0.001) during forearm exercise compared with the control study. Insulin clamp was also associated with an increase in total work performed (56%) during exercise. Our findings demonstrate that resistance to the biological actions of insulin, as occurs in type II diabetes mellitus, leads to a defect in glucose transport that limits the availability of extracellular glucose to exercising muscle. In our subject with a substrate-limited skeletal muscle metabolism (MD), reversal of this defect in insulin-dependent glucose transport by a hyperinsulinemic euglycemic clamp was associated with significant improvement in magnetic resonance spectroscopy parameters of skeletal muscle metabolism as well as exercise performance.

Structure-function relationships within peripheral nerves in diabetic neuropathy: the hydration hypothesis.

To define the quantitative relationship between peripheral nerve structure and function imposed by endoneurial oedema in the diabetic state, we determined values for sural nerve hydration structure as measured by magnetic resonance spectroscopy, and for neurological function with scores for nerve conduction properties (NCV-score), neuropathic symptoms (NS-score), and examination signs (NE-score). The coefficient of sural nerve hydration was elevated to 30 +/- 6% (p < 0.05) in 79 symptomatic neuropathic diabetic subjects with an average of 15 years of diabetes mellitus, compared to a value of 25 +/- 3% in 72 non-diabetic control subjects. In contrast, in 75 asymptomatic diabetic subjects with an average of 6 additional years of diabetes, the mean hydration coefficient was only 28 +/- 5% (p < 0.05). A nerve hyperhydration state was identified with a prevalence of 25% within the asymptomatic group characterized by nerve hydration greater than the 95th percentile, early changes in nerve electrophysiology and neurological examination, but with no symptomatology of neuropathy. Stratification of the symptomatic neuropathic group by worsening nerve electrophysiology, demonstrates a coincident deterioration in neurological examination (RR = 5.39 at maximum NCV-score), and neuropathy symptomatology (RR = 4.80 at maximum NE-score). The present data are consistent with the hypothesis that endoneurial oedema initiates deterioration sequentially in nerve electrophysiology, followed by abnormal findings on neurological examination, preceding the patient's final perception of symptomatic stocking glove peripheral diabetic neuropathy.

Increased levels of methylglyoxal-metabolizing enzymes in mononuclear and polymorphonuclear cells from insulin-dependent diabetic patients with diabetic complications: aldose reductase, glyoxalase I, and glyoxalase II--a clinical research center study.

Levels of aldose reductase, glyoxalase I, and glyoxalase II in mononuclear and polymorphonuclear cells from insulin-dependent diabetes mellitus (IDDM) patients with long term diabetic complications were compared to levels in IDDM patients without complications and to those in nondiabetic controls. Cells were isolated from 22 asymptomatic long term IDDM patients, 22 symptomatic IDDM patients, and 16 controls, using a double gradient centrifugation procedure. Aldose reductase was determined by Western blots using polyclonal antiserum to human aldose reductase purified from skeletal muscle. Glyoxalase I and glyoxalase II were determined spectrophotometrically. Aldose reductase in mononuclear cells from symptomatic IDDM patients is significantly elevated compared to that in asymptomatic IDDM patients (mean +/- SEM, 0.96 +/- 0.20 vs. 0.46 +/- 0.08 microgram/mg protein; P < 0.02). Aldose reductase was not detected in polymorphonuclear cells. Glyoxalase I in mononuclear and polymorphonuclear cells from symptomatic IDDM patients is significantly elevated compared to that in controls [mean for mononuclear cells, 0.46 +/- 0.03 vs. 0.37 +/- 0.03 mumol/min.mg (P < 0.05); mean for polymorphonuclear cells, 0.16 +/- 0.01 vs. 0.10 +/- 0.01 mumol/min.mg (P < 0.002)]. Glyoxalase II is significantly elevated only in polymorphonuclear cells from symptomatic IDDM patients compared to controls (mean, 0.13 +/- 0.01 vs. 0.063 +/- 0.016 mumol/min.mg; P < 0.005). Glutathione peroxidase and glutathione S-transferase were not significantly different in these populations. Aldose reductase, glyoxalase I, and glyoxalase II are involved in the metabolism of methylglyoxal, suggesting that methylglyoxal may play a role in the etiology of diabetic complications.

Segmentation of small structures in MR images: semiautomated tissue hydration measurement.

Segmentation of small anatomic structures in noisy magnetic resonance (MR) images is inherently challenging because the edge information is contained in the same high-frequency image component as the noise. The authors overcame this obstacle in the analysis of the sural nerve in the ankle by processing images to reduce noise and extracting edges with an edge detection algorithm less sensitive to noise. Anatomic accuracy of the segmentation was confirmed by a neuroradiologist. A nerve hydration coefficient was determined from the signal intensity of the nerve in these segmented images. These semiautomated measurements of hydration agreed closely with those obtained with a previously described manual method (n = 44, P = .76). Each image in the study was analyzed identically, with no modification of the computer algorithm parameters. The data suggest that this robust method may be useful in a multicenter evaluation of diabetes treatment protocols.

Polyol and water accumulation in muscle of galactose-fed rats.

Skeletal muscle contains high levels of aldose reductase that catalyzes the reduction of galactose to the polyol galactitol. Galactitol and water were measured in muscle of rats fed a high galactose diet with or without addition of the aldose reductase inhibitor sorbinil. Galactitol, measured in isolated samples of muscle by HPLC, reached steady-state levels (5.9 +/- 1.0 mg/g tissue) within 3 days. Muscle water, determined in vivo by magnetic resonance imaging, increased (51 +/- 5%, P < 0.02) to steady-state levels within 7 days. Both the increased galactitol and water remained constant for the 4-month duration of this study. Aldose reductase activity also remained constant. Sorbinil prevented both the increase in galactitol and the increase in water. These results suggest that the increase in water is due to the osmotic effects of galactitol accumulation and demonstrate that galactitol and water accumulation neither up-regulate nor down-regulate aldose reductase expression in skeletal muscle.

Sural nerve water in vivo in normal humans measured by magnetic resonance spectroscopy: relation to age, height, gender, and neurological profile.

To enable the quantitative assessment of peripheral nerve structure and function, we determined the normal values for sural nerve hydration structure as measured by magnetic resonance proton imaging, and for neurological function with scores for neuropathic symptoms, signs, and nerve conduction properties. Normal human sural nerves contain 24.8 +/- 3.4% water. The structural water content of the nerves did not vary systematically in relation to age, height, gender, sural nerve conduction, neurologic symptoms, or examination deficits. In contrast, the neurological function scores were significantly influenced by age and selectively by height. Both nerve structure and function were stable over a 1-year interval. Measurement of human sural nerve water content in vivo by magnetic resonance proton imaging, and quantitation of the neurological profile of symptoms, signs, and conduction velocity are useful, noninvasive tools for the investigation of diseases in which changes in nerve structure may be related to alterations in nerve function.

Long-term implantation of a new implantable programmable insulin pump in two diabetic dogs.

A positive-pressure implantable programmable pump with an integrated sideport and a detachable catheter was tested for long-term intraperitoneal insulin delivery in 2 diabetic dogs. Programming and refilling of the pump was simple and presented no problems during 28 months of pump function. During pump therapy an acceptable degree of glycemic control was maintained. No catheter occlusion occurred, and no skin erosions or infections were observed. Insulin in the pump reservoir was stable. After 9.5 months of pump function, flow progressively decreased because of insulin precipitation in the valved accumulator. Solubilization of these precipitates using 0.1 N NaOH injected in the reservoir and drained through the sideport normalized pump delivery rates. We conclude that this device is safe for long-term intraperitoneal insulin delivery. The sideport enables discrimination between different causes of pump malfunction and allows for the safe use of an alkaline solution to remove insulin precipitates, thus avoiding pump explantation.

Noninvasive glucose monitoring in diabetic patients: a preliminary evaluation.

Noninvasive monitoring of blood/tissue glucose concentrations has been successfully accomplished in individual diabetic subjects by using near-infrared (NIR) spectroscopy coupled with chemometric methods. Three different spectrometer configurations were tested: a) a Fourier-transform infrared spectrometer with an indium antimonide detector; b) a grating monochromator equipped with a silicon (Si) array detector, without fiber optics; and c) a grating monochromator equipped with an Si detector, with fiber-optic sampling. NIR spectra were obtained from diabetic subjects by transmission through the finger during a meal-tolerance test. The maximum range of observed plasma glucose concentrations obtained from the blood samples was 2.5-27 mmol/L. The NIR spectra were processed by using the chemometric multivariate calibration methods of partial least squares and principal component regression. The best calibration yielded a cross-validated average absolute error in glucose concentration of 1.1 mmol/L. This predictive ability suggests that noninvasive glucose determinations by NIR/chemometrics is a viable analytical method.

Increased urinary prostaglandin excretion in galactose-fed rats.

Increased renal production of prostaglandins (PG) may contribute to the hyperfiltration that accompanies early diabetes. It was postulated that a putative metabolic abnormality of diabetes, ie, increased flux through the polyol pathway, stimulates renal PG production and that this phenomenon can be prevented by aldose-reductase inhibition. To test this hypothesis, the effects of polyol accumulation on urinary excretion rates (UER) of PGE2 and 6-keto-PGF1 alpha were studied, using the galactose-fed rat model. UER of PGE2 and 6-keto-PGF1 alpha were measured in three groups of weanling Wistar male rats. Group 1 was maintained on normal chow (n = 6), group 2 was fed chow supplemented with 30% galactose (n = 6), and group 3 received chow supplemented with 30% galactose and 0.7% sorbinil (n = 6). Ten 24-hour urine samples were obtained from each group between 151 and 240 days on the respective diets. UER of PGE2 (P less than .001) and 6-keto-PGF1 alpha (P less than .01) were higher in group 2 than in group 1. UER of PGE2 (NS) and 6-keto-PGF1 alpha (NS), respectively, were similar in groups 1 and 3. These data indicate that flux through the polyol pathway modulates the UER of PGE2 and 6-keto-PGF1 alpha. This phenomenon may contribute to the glomerular hyperfiltration of early diabetes.

Glucose inhibition of human fibroblast proliferation and response to growth factors is prevented by inhibitors of aldose reductase.

Diabetes mellitus is associated with premature senescence of cultured dermal fibroblasts. The present study investigated the effect of elevated glucose concentrations on cultured human fibroblasts from normal donors. Mean population doubling times, population doublings until senescence, saturation density at confluence (cells/cm2), tritiated thymidine incorporation, and response to platelet-derived growth factor (PDGF) were inhibited with the increasing glucose concentrations (11.0, 22, 44, or 55 mM glucose) (P less than 0.05). Replicative life span was markedly diminished by multiple passages in high glucose medium (5.5 mM glucose: 62.4 +/- 7.9 population doublings; 22 mM glucose: 22.8 +/- 3.4 population doublings: P less than 0.05). Aldose reductase activity was present in the cultured fibroblasts (3.9 +/- 0.5 nmol/min per mg protein), and inhibitors of aldose reductase, including sorbinil (10(-4) M--10(-6) M) and tolrestat (10(-6) M--10(-8) M), completely prevented glucose-mediated inhibition of fibroblast proliferation, restored the response to PDGF, and allowed a normal replicative life span. Myo-inositol (11 microM--5.5 mM) also reversed the adverse effects of glucose. These in vitro data demonstrate that elevated concentrations of glucose inhibit cell growth and promote premature senescence, effects which can be prevented with inhibitors of aldose reductase or supplemental myo-inositol. These aldose reductase-related effects may explain the impaired growth and premature senescence of cultured connective tissue from diabetic patients.