Decreased bone mineral density at the distal radius, but not at the lumbar spine or the femoral neck, in Japanese type 2 diabetic patients.

The purpose of this study is to assess the association between type 2 diabetes and bone mineral density. This study included 145 Japanese patients (64 men and 81 women) with type 2 diabetes and 95 non-diabetic control subjects (41 men and 54 women) of similar age. We measured bone mineral density (BMD) at the sites with different cortical/cancellous bone ratio (lumbar spine, femoral neck, and distal radius) using dual-energy X-ray absorptiometry. BMD and Z score at the distal radius were significantly lower in type 2 diabetic patients than those in control subjects, and in type 2 diabetic patients, the Z score at the distal radius was lower than that at their own lumbar spine and femoral neck. In type 2 diabetic patients, negative correlation between BMD and the mean HbA1c during the previous 2 years was found significantly at the distal radius in both genders and at the femoral neck in women. These results indicate the selective cortical bone loss in type 2 diabetes and suggest the importance of also determining BMD at the radius and keeping good metabolic control to prevent bone loss in type 2 diabetic patients.

Familial spinal xanthomatosis with sitosterolemia.

A family with multiple spinal xanthomas and sitosterolemia is described. A 48-year-old woman presented with paraplegia due to multiple intradural extramedullary tumors. The patient also showed marked tendon xanthomas and analysis of sterol composition in both plasma and the xanthoma established the diagnosis of the rare inherited metabolic disease, sitosterolemia and xanthomatosis. Two other siblings in the family presented with marked tendon xanthomas and coronary atherosclerosis, but did not show any neurological signs or symptoms. Magnetic resonance imaging (MRI) study revealed multiple intradural extramedullary tumors in spinal canals of the proband and her sister, but not in the other affected sibling (brother). This is the first report of familial occurrence of multiple extramedullary spinal tumors due to the inherited metabolic abnormality.

[A case of sitosterolemia with spastic gait due to intradural-extramedullary xanthoma].

A forty-eight-year-old woman with a 30 years history of tendinous xanthomatosis developed spastic gait and mild urinary incontinence. Myelography, metrizamide-enhanced CT and magnetic resonance image revealed multiple intradural-extramedullary tumors extending from C1 to Th7. The gait disturbance entirely disappeared by the removal of the tumors. Morphological examination of the tumors showed xanthogranulomatosis. The analysis of her sera and tumors revealed increased amount of plant sterols, especially beta-sitosterol and the diagnosis was made as beta-sitosterolemia. Tendinous xanthoma and beta-sitosterolemia were seen in 2 of 6 her brothers but none showed neurological symptoms. This is the first case of sitosterolemia with neurological complication i.e., spinal cord compression due to extramedullary sitosterolemia xanthomas.

Spinal cord compression with paraplegia in xanthomatosis due to normocholesterolemic sitosterolemia.

A 48-year-old woman with a 30-year history of tendinous xanthomatosis developed paraplegia. The magnetic resonance image revealed extramedullary tumors. The analysis of her sera and tumors revealed increased amount of plant sterols, especially sitosterol, and the diagnosis of sitosterolemia was made. This is the first reported case of a patient with sitosterolemia who had the neurological complication of spinal cord compression due to extramedullary sitosterolemic xanthomas.

Increased plasma plant sterol levels in heterozygotes with sitosterolemia and xanthomatosis.

Plasma sterol levels in a family of sitosterolemia and xanthomatosis were determined by a high performance liquid chromatography. Three affected siblings manifested marked xanthomatosis including subcutaneous soft tissues and generalized atherosclerosis. Two other siblings as well as children of the patients did not show such clinical symptoms and signs. Plasma levels of cholesterol, sitosterol, campesterol, and cholestanol in three affected subjects were 190 +/- 18.5, 25.9 +/- 11.6, 16.1 +/- 7.8, 1.84 +/- 0.92 mg/dl (mean +/- SD), respectively. Four daughters of the affected subjects, who should be considered as obligatory heterozygotes, showed moderately increased levels of these sterols (195 +/- 41.7, 1.33 +/- 0.44, 1.56 +/- 0.69, 0.80 +/- 0.28 mg/dl), which were significantly higher than those of normal subjects. Treatment with cholestyramine had little effect on the increased plasma plant sterol levels, but markedly decreased plasma cholestanol concentrations in two affected siblings. This report presents the clinical features of the patients with sitosterolemia and xanthomatosis and also demonstrates that heterozygotes with this disorder have increased plasma levels of plant sterols as well as cholestanol, and suggests that this rare disease might be inherited as an autosomal co-dominant trait in certain cases. The data also indicate that cholestyramine administration was not effective in this family for treatment of sitosterolemia.

Morphological characteristics of dermal diabetic microangiopathy.

In an attempt to characterize dermal diabetic microangiopathy, dermal microvessels were qualitatively and quantitatively assessed in 26 healthy control subjects and 47 non-insulin-dependent diabetic patients. Basement membrane thickness (BMT) was significantly greater and the homogeneous BM more frequent in diabetic than in control microvessels. BMT did not change with duration of diabetes but significantly decreased with age and onset age of diabetes, suggesting either a different process of BM thickening with respect to age in diabetic dermal microvessels or the implication of genetic influence on the pathogenesis of dermal diabetic microangiopathy. Endothelial cell hyperplasia was not noted in dermal diabetic microvessels. In view of the fact that the hyperplasia has been reported in other tissues and is closely associated with diabetic microangiopathy, the nature of dermal microvessels or endothelial cells or the milieu around dermal microvessels might be different from other organs.

Effect of prostaglandin E1 analogue TFC 612 on diabetic neuropathy in streptozocin-induced diabetic rats. Comparison with aldose reductase inhibitor ONO 2235.

The effect of a newly developed oral agent, prostaglandin E1 (PGE1) analogue TFC 612, on diabetic neuropathy was studied by giving it for 6 wk to streptozocin-induced diabetic rats that had been diabetic for 3 mo and was compared with the effects of aldose reductase inhibitor ONO 2235. Although both compounds improved decreased motor nerve conduction velocity, the effect of TFC 612 continued during the 6 wk of treatment, whereas that of ONO 2235 became weaker from wk 4. The abnormality in sciatic nerve sorbitol and myo-inositol levels was reversed with ONO 2235, whereas it was unchanged with TFC 612. With the laser Doppler flowmetry technique, a decrease in the sciatic nerve blood flow in diabetic rats was shown to improve with both compounds, but TFC 612 had a greater effect than ONO 2235, and the increased lactate level of the diabetic nerve was corrected with both compounds, suggesting that both may be associated with the amelioration of ischemia in the diabetic endoneurium. Both TFC 612 and ONO 2235 partially but significantly normalized decreased fiber size in diabetic rats. On the other hand, TFC 612 completely normalized the dilated lumen area in diabetic rats, whereas ONO 2235 did not. These results suggest that the PGE1 analogue TFC 612 has a significant effect on diabetic neuropathy, possibly via vasotropic action, and may be a potent compound for the treatment of diabetic neuropathy.

Chronically streptozocin-diabetic monkey does not closely mimic human diabetic neuropathy.

In order to evaluate the value of diabetic Japanese monkeys (Macaca fuscatus) as an animal model for studying the pathogenesis of diabetic neuropathy, morphological examinations were performed on myelinated nerve fibers and endoneurial microvessels at three levels of the lower limb nerve in eight streptozocin (STZ)-diabetic monkeys with the duration of diabetes up to 36 months and in four roughly age-matched control monkeys using a computer-assisted image analyzer. Nerve fiber loss was not found, although a tendency for nerve fiber atrophy was found in diabetic monkeys. Endoneurial microvessels did not show either endothelial or pericyte proliferation or basement membrane thickening. The results suggest that chronically STZ-diabetic Japanese monkeys with the duration of diabetes up to 36 months might be useful for studying diabetic axonopathy, but do not closely mimic the nerve pathology found in human diabetic neuropathy.

A new prostaglandin E1 analogue (TFC-612) prevents a decrease in motor nerve conduction velocity in streptozocin-diabetic rats.

A new prostaglandin E1 analogue (TFC-612) was orally given to streptozocin-diabetic rats for 4 weeks after the induction of diabetes and its effects on motor nerve conduction velocity were studied. The compound significantly prevented a decrease of the velocity but did not reverse abnormal sorbitol and myo-inositol contents of the sciatic nerve. The results suggest that TFC-612 has a potent effect on diabetic nerve dysfunction via other mechanism than the correction of sorbitol and myo-inositol metabolisms and could be a potential compound for therapy of diabetic polyneuropathy.

Thyrotropin-releasing hormone reduces myo-inositol content in rat cerebellum pretreated with lithium.

The effect of thyrotropin-releasing hormone (TRH) and lithium on myo-inositol metabolism has been assessed in rat cerebral cortex, cerebellar cortex, and sciatic nerves. Sprague-Dawley male rats were injected subcutaneously with 10 mEq/kg of LiCl and intraperitoneally with 10 mg/kg of TRH-tartrate, alone or in combination. Either lithium or TRH alone had little effect on the myo-inositol concentration in cerebellar cortex, whereas the combination of lithium and TRH significantly lowered the level. The myo-inositol level of cerebellar cortex reached its nadir (70% of values in untreated control rats) 30 min after addition of TRH and then returned to the control level at 90 min. In cerebral cortex, both lithium alone and lithium plus TRH significantly reduced the myo-inositol level. No effect was seen on the myo-inositol concentration in sciatic nerves with these regimens. These results suggested that the pharmacological dose of TRH activated phosphatidylinositol turnover in rat cerebellar cortex and subsequently reduced the myo-inositol level in the presence of lithium.

Skin biopsy as a beneficial procedure for morphological evaluation of diabetic neuropathy.

In an attempt to evaluate the morphological abnormalities of dermal non-myelinated nerve fibers of diabetics and elucidate the pathogenesis of diabetic peripheral neuropathy, the terminal part of peripheral nerve in the upper dermis was observed on electron microscopy using skin samples biopsied in 10 diabetics with symptomatic neuropathy and 6 age-matched controls. In diabetics, the density of nerve fibers was significantly lower than in controls. In addition, swelling, lytic change and vacuolation in the axon, multiplication of basement membrane of the Schwann cell and Schwann cell cluster devoid of axon were more frequently observed in diabetics. The Schwann cell did not show significant structural alterations. These findings suggest that the axon is primarily involved, at least in the terminal region of nerve fiber, in diabetic peripheral neuropathy. It is also concluded that the skin biopsy technique is harmless, cosmetically not troublesome and might be beneficial for studying peripheral neuropathies including diabetic neuropathy.

Effects of a new aldose reductase inhibitor on various tissues in vitro.

A new aldose reductase inhibitor, ONO-2235 [(E)-3-carboxymethyl-5-[(2E)-methyl-3-phenylpropenylidene] rhodanine], was found to possess a potent inhibitory activity of aldose reductase, partially purified from rat lens (IC50 = 1.0 X 10(-8) M) and human placenta (IC50 = 2.6 X 10(-8) M). Against rat lens aldose reductase, ONO-2235 exhibited uncompetitive inhibition as previously observed with 7-hydroxy-4-oxo-4H-chromen-2-carboxylic acid. Sorbitol accumulation in the isolated rat lenses, sciatic nerves and human erythrocytes were all effectively inhibited during incubation with high concentrations of glucose (28-50 mM) by ONO-2235 at a concentration of about 10(-6) M. Because the accumulation of sorbitol has been reported to play an etiological role in the development of diabetic complications, the results suggest that ONO-2235 may prove to be useful in preventing and improving some diabetic complications.

Prevention of peripheral nerve dysfunction by an aldose reductase inhibitor in streptozotocin-diabetic rats.

A potent inhibitor of aldose reductase, (E)-3-carboxy-methyl-5-[(2E)-methyl-3-phenylpropenylidene]rhodanin e (ONO-2235), was orally administered at a dose of 20 mg X kg-1 X d-1 for 2 weeks to streptozotocin-diabetic rats from the beginning of the diabetic state, ie, 24 hours after streptozotocin injection. The impairment of motor nerve conduction velocity (MNCV) of the tail nerve found in nontreated diabetic rats was apparently prevented by the treatment with the aldose reductase inhibitor (24.5 +/- 0.4 v 29.0 +/- 1.4 m/s on day 14, P less than 0.005). Those diabetic rats treated with the compound actually showed an age-dependent increase in MNCV similar to that of normal control rats (25.5 +/- 1.5 v 26.4 +/- 1.0 m/s on day 7, 29.0 +/- 1.4 v 29.4 +/- 1.3 m/s on day 14, treated v normal, not statistically significant on both days). The sorbitol content of the sciatic nerve excised from ONO-2235-treated diabetic rats (0.067 +/- 0.018 nmol/g wet weight) was significantly lower than that of the nontreated diabetic rats (1.309 +/- 0.080 nmol/g wet weight, P less than 0.001) but significantly higher than that of normal control rats (0.229 +/- 0.015 nmol/g wet weight, P less than 0.001). These results suggest that the reduction in MNCV noted in the experimental diabetic animals is not the result of retarded maturation of peripheral nerves but of metabolic derangement caused by the diabetic state, which can be prevented by suppressing sorbitol accumulation in nerve tissue. It also appears that there may be a threshold level of sorbitol accumulation that causes the impairment of nerve conduction velocity.

Insulin release from BK virus-induced and in vitro maintained insulinoma cells of Syrian golden hamster.

The pancreatic tumor cells (In 111) derived from BK virus-induced insulinoma of Syrian golden hamsters were maintained in culture for several passages and were studied for their insulin secretory ability under various stimulatory conditions. Insulin release was not increased by D-glucose stimulation (27.8 mM), while dibutyryl cyclic AMP (1 mM), theophylline (1 mM), 3-isobutyl-l-methylxanthine (0.1 mM) and elevation of medium calcium from 0.5 to 2.7 mM stimulated insulin release 2.5- to 4-fold. There was a concomitant increase of medium cyclic AMP with addition of theophylline. Streptozotocin (2 mM) treatment for 48 hours significantly reduced insulin release, while alloxan (2 mM), had no inhibitory effect on insulin release. The results indicate that while in vitro-maintained islet tumor cells, In 111, have a cyclic AMP-mediated process involved in insulin secretion analogous to normal beta cells, these cells lack the ability to recognize glucose as an insulin secretagogue probably due to a defect in the cell membrane, though the possibility of alteration in glucose metabolism cannot be fully excluded.

Effect of a new aldose reductase inhibitor, (E)-3-carboxymethyl-5-[(2E)-methyl-3-phenylpropenylidene]rhodanine (ONO-2235) on peripheral nerve disorders in streptozotocin-diabetic rats.

A new aldose reductase inhibitor, (E)-3-carboxymethyl-5-[(2E-methyl-3-phenylpropenylidene]rhodanine (ONO-2235) was administered orally to streptozotocin-diabetic rats (60 mg/kg IV) for 14 days and its effect on motor nerve conduction velocity studied. The compound significantly improved motor nerve conduction velocity of diabetic rats at a minimal dose of 10 mg . kg-1 . day-1 (treated 28.8 +/- 0.5 versus untreated 23.2 +/- 4.7 m/s, p less than 0.01). The sorbitol content of the sciatic nerve and red blood cells measured after 2 weeks was concomitantly reduced in ONO-2235-treated rats (sciatic nerve: 120 +/- 13 versus 595 +/- 146 nmol/g wet weight; red blood cell: 91 +/- 21 versus 165 +/- 39 nmol/g haemoglobin; p less than 0.01 in both 20 mg . kg-1 . day-1-treated versus untreated animals). These results suggest that sorbitol accumulation might contribute to the development of peripheral nerve dysfunction in acutely diabetic animals and the new aldose reductase inhibitor could be a potential drug for therapy of diabetic neuropathy.