Effects of STA-MCA anastomosis for ischaemic oculopathy due to occlusion of the internal carotid artery

Summary Effects of STA-MCA anastomosis on two patients with neovascular glaucoma due to occlusion of the internal carotid artery are presented. Both patients improved in visual acuity and central retinal artery pressure as well as in signs of transient ischaemic attack. Postoperative angiography showed a marked decrease in collateral flow through the ophthalmic artery, which is reversed from the normal direction, with the development of blood flow through the anastomosis. Discussion is offered indicating that the lack of collateral flow through both the anterior and posterior communicating arteries is important in addition to occlusion of the internal carotid artery in order to produce full-blown ischaemic oculopathy such as venous stasis retinopathy, neovascular glaucoma or rubeosis iridis. It is stressed that EC-IC bypass surgery should be performed soon after the appearance of ischaemia and before the development of neovascular glaucoma or rubeosis iridis in order to obtain normal vision. In ischaemic oculopathy the results of EC-IC bypass can be evaluated objectively and quantitatively by many noninvasive neuro-ophthalmological tests which are important in discussing the efficacy of the bypass surgery.     

Diabetes mellitus and hearing loss

A prospective hearing survey was performed in a sample of 102 diabetic patients. The hearing data were compared with the hearing thresholds of three control population groups. A significant difference was found in the average hearing thresholds between the diabetic patients and all of the three control populations. Diabetic patients have worse hearing threshold levels especially at low and mid frequencies (P < 0.001). There was also a correlation between the duration of diabetes and hearing loss. No significant correlation was found between the different stages of diabetic retinopathy and the degree of hearing loss.     

肝硬化患者胰岛素释放试验的临床意义

本文报道46例肝硬化患者口服葡萄糖胰岛素释放试验的结果,并与18名正常人和18名原发性糖尿病患者比较。肝硬化患者糖耐量减低者28例(60.9％),其中29例(43.5％)呈糖尿病型耐量曲线。胰岛素释放高峰值在服糖后2h;释放过多和分泌延迟者32例(69.6％),降低者4例(8.7％)。20例肝源性糖尿病患者的胰岛素释放指数明显高于原发性糖尿患者。笔者认为血浆胰岛素和胰岛素释放指数测定对鉴别这两种类型的糖尿病有很大价值。     

Aldose reductase inhibition with imirestat — effects on impulse conduction and insulin-stimulation of Na+/K+-adenosine triphosphatase activity in sciatic nerves of streptozotocin-diabetic rats

Summary This study describes reduced motor nerve conduction velocity and increased resistance to hypoxia-induced conduction failure in sciatic nerves of rats after four weeks of streptozotocin-induced diabetes (both effects were significant at p <0.05). These changes occurred in the absence of any deficit in the steady-state ouabain-sensitive adenosine triphosphatase (ATPase) activity of sciatic nerve endoneurial homogenates. The addition of 10 nmol/l insulin to endoneurial homogenates from control animals resulted in a 34% increase in ouabain-sensitive ATPase activity and a 19% reduction in ouabain-insensitive ATPase activity (both p <0.01). This stimulation of ouabain-sensitive ATPase activity by insulin did not occur in homogenates from diabetic rats. Treating diabetic rats daily with the aldose reductase inhibitor, imirestat (1 mg/kg) improved nerve conduction velocity (p <0.05) but was without effect upon the resistance to hypoxic conduction blockade or the deficit in insulin-stimulated oubain-sensitive ATPase activity. These data suggest that in streptozotocin-diabetic rats the functional disorders of reduced motor nerve conduction velocity and increased resistance to hypoxic conduction blockade do not share a common aetiology and that impaired nerve conduction is not related to reduced maximal potential oubain-sensitive ATPase activity.     

The prevalence and expression of diabetes in a sample of optometric patients

The clinical characteristics of 100 consecutively presenting diabetic patients of an optometrist were investigated. This sample was drawn from 3798 patient first visits and represented 2.6% of the practice population sample. Diabetic retinopathy was present in 26% of the diabetic patients; this prevalence is similar to that found in diabetics examined in community based surveys. The ocular complications of diabetics observed in this study appeared to be similar to those of diabetics in the general community. The mean random blood glucose levels of the diabetics having retinopathy was not significantly different from those not having retinopathy. A first degree family history of diabetes was admitted by 46% of the diabetic subjects and was the most common associated clinical feature surveyed; a control group of non-diabetic subjects had a first degree family history of diabetes in 10% of cases. In seven patients, the diabetes was diagnosed as a result of signs detected at the optometric examination; these signs are listed. No newly diagnosed diabetic had diabetic retinopathy as a presenting sign. Ocular and systemic signs, other than diabetic retinopathy, were sought and a high prevalence of cardiovascular disease was detected in these diabetic patients. The vision of the diabetic patients was compared to that of 100 randomly selected age and sex matched controls; there was no significant difference in the visual acuity of the two groups. The implications of this finding are discussed. Guidelines for the detection and management of diabetic patients of optometrists are suggested.     

Dual blockade of the renin-angiotensin system in type 1 patients with diabetic nephropathy.

BACKGROUND: Albuminuria and hypertension are predictors of poor renal and cardiovascular outcome in patients with diabetes. Approximately 30% of type 1 patients with diabetic nephropathy (DN) have albuminuria >1 g/day, and blood pressure >135 and/or >85 mmHg despite antihypertensive therapy with recommended doses of ACE inhibitor (ACEI) and diuretics. We tested the effect of dual blockade of the renin-angiotensin system (RAS) in these patients. METHODS: We performed a randomised double blind crossover trial with 2 months treatment with Irbesartan 300 mg o.d. and placebo added on top of previous antihypertensive treatment. We included 21 type 1 patients with DN responding insufficiently to ACEI and diuretics, as defined above. At the end of each treatment period, albuminuria, 24-h blood pressure and glomerular filtration rate (GFR) were measured. RESULTS: Addition of 300 mg Irbesartan to the patients' usual antihypertensive therapy induced a mean reduction in albuminuria of 37% (95% CI 20-49, P<0.001); from 1574 mg/24 h (95% CI 1162-2132) to 996 mg/24 h (95% CI 699-1419), a reduction in 24-h blood pressure of 8 mmHg systolic (95% CI -2 to 18) and 5 mmHg diastolic (95% CI 1-9) (P=0.11 and 0.01, respectively) (from placebo, mean (SE) 146 (4)/80 (2) mmHg). GFR remained unchanged. Serum potassium increased (mean 4.3 to 4.6 mmol/l, P=0.02). Intervention to reduce serum potassium was needed in two patients with GFR <35 ml/min/1.73 m(2). Otherwise the dual blockade with Irbesartan was safe and well tolerated. CONCLUSIONS: Dual blockade of the RAS may offer additional renal and cardiovascular protection in type 1 patients with DN responding insufficiently to conventional antihypertensive therapy, including recommended doses of ACEI and diuretics.     

Effect of morphological abnormalities on blood retinal barrier permeability in diabetic retinopathy

The morphological base for the impaired function of the blood retinal barrier was studied in 50 eyes of 10 insulin dependent and 21 non-insulin dependent patients with various levels of diabetic retinopathy. The permeability of the blood retinal barrier (P_BRB) was determined by vitreous fluorophotometry with correction for autofluorescence, lenstransmission and non-protein bound plasma fluorescein concentration. Morphological abnormalities of diabetic retinopathy assessed by fundus photography and fluorescein angiography were individually scored on a decimal scale and related to the P_BRB by multiple regression analysis. The P_brb was not correlated to morphological abnormalities of non-proliferative retinopathy [(1) microaneurysms, (2) hard exudates, (3) soft exudates, (4) intraretinal hemorrhages, (5) fluorescein leakage, and (6) capillary closure, p > 0.3]. The P_BRB was correlated to morphological abnormalities of (pre)proliferative retinopathy [(1) intraretinal microvascular abnormalities (S_irma) and (2) new vessels (S_neo): p_brb = A – B.S_IRMA – C.S_neo with P_BRB in nm/sec, A = 1.5 ± 0.5, B = 0.9 ± 0.2 and C = 1.7 ± 0.4, R² = 0.65, p < 0.0001]. It can be concluded that the increased blood retinal barrier permeability in diabetic patients is mainly due to (pre)proliferative abnormalities and not to non-proliferative abnormalities.     

Activity and distribution of phosphoinositidase C in rat sciatic nerve.

The hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2) by rat sciatic nerve cytosolic phosphoinositidase C [phosphoinositide-specific phospholipase C (PIC)] was studied at neutral pH and at ionic concentrations that approximate intracellular conditions. The principal water-soluble product formed was shown to be inositol trisphosphate by anion exchange chromatography. The maximum hydrolysis rate (2.5 nmol/min/mg protein) was achieved at less than 100 nM Ca2+. Hydrolysis was markedly increased to 15 nmol/min/mg protein by inclusion of K+ in the reaction mixture. In the presence of 200 mM K+, the optimum Ca2+ was increased to approximately 600 nM. Higher Ca2+ concentrations progressively inhibited PIP2 hydrolysis. Mg2+ also inhibited the reaction, but the presence of equimolar amounts of ATP and Mg2+ had no effect. Appreciable degradation of phosphatidylinositol-4-phosphate (PIP) also occurred in the nanomolar Ca2+ range, whereas breakdown of phosphatidylinositol (PI) required millimolar Ca2+. The presence of PIP but not PI inhibited PIP2 hydrolysis. Upon subcellular fractionation of nerve, more than 50% of recovered PIC activity was in the cytosol and about 20% was located in a myelin-enriched fraction. Using PIP2 as substrate, PIC activities in nerves from normal and streptozotocin-induced diabetic animals were not different. However, the myelin-associated enzyme from diabetic animals was more labile to freezing and thawing.     

Neuropathy in children and adolescents with diabetes mellitus

Nerve conduction velocities were studied in the median, posterior tibial, radial and sural nerves of 50 juvenile diabetics, average age 13 +/- 1.3 years and mean duration of diabetes 2.3 +/- 1.4 years. Motor conduction velocity (MCV) in the median nerve was reduced in 10% of the subjects, and in the posterior tibial in 32%. Sensory conduction velocity (SCV) in the radial nerve was reduced in 30% of the subjects, and in the sural in 44%. No relationship was found between the reduction in conduction velocity and the duration of diabetes; nevertheless, a correlation was observed between this reduction and the degree of glycaemic control represented by the glycosylated haemoglobin concentration. The authors emphasize the importance of good glycaemic control for the prevention of diabetic neuropathy.