HLA-DQB1*0201/0302 is associated with severe retinopathy in patients with IDDM

Some insulin-dependent diabetic (IDDM) patients develop severe forms of retinopathy. Putative risk factors such as hypertension, poor metabolic control, nephropathy and growth hormone levels do not fully explain the progress of retinopathy in these patients. It has been discussed whether there is a genetic marker, since some diabetic patients without any known predisposing risk factors develop severe retinopathy and others do not. In the present study, HLA-DR and DQ were compared in two patient groups with IDDM. One group consisted of patients with early-onset diabetes, with severe non-proliferative or proliferative retinopathy; the other group had no or only mild signs of retinopathy. High resolution HLA typing was carried out by polymerase chain reaction (PCR) and hybridization with allele specific probes. Alleles on the DR3-DQ2 haplotype, DRB1*0301, DQA1*0501 and DQB1*0201, were more frequent in patients with severe retinopathy. A difference was seen when combining certain alleles in the genotypes of DQA1*03/0501 (p > 0.05) and DQB1*0201/0302 (p < 0.01). The findings of the present study suggest that DQB1*0201/0302 is the strongest genetic marker for severe retinopathy and DRB1*0301/0401 only has a secondary influence when combined with this genotype. It seems as if IDDM patients who are positive for the genotype DR3-DQ2/DR4-DQ8 (DRB1*0301-DQA1*0501-DQB1*0201/DRB1*0401 -DQA1*03-DQB1*0302) are at greater risk of developing severe retinopathy.

Retinal nitro blue tetrazolium staining and catalase activity in rat models of diabetes

BACKGROUND

Recent studies have suggested that reactive oxygen species may be involved in the development of diabetic retinopathy.

METHODS

Nitro blue tetrazolium (NBT) staining, a marker of reductants which may be induced by free radicals such as superoxide, and catalase activity, as an indirect measure of hydrogen peroxide (H2O2) generation, were studied in the rat retina in three conditions known to cause diabetes-like retinopathy, i.e. rats with spontaneous diabetes (the BB Wistar rat), rats with streptozotocin-induced diabetes mellitus, and rats fed on galactose. Male Wistar BB rats were studied 4-10 weeks after diagnosis of diabetes. Streptozotocin (60 mg/kg) was injected i.p. at 8 weeks of age and the experiments were performed after 8 weeks of diabetes. Young Sprague-Dawley rats were fed a 50% galactose diet for 9, 12 or 22 months.

RESULTS

In trypsinized vessel preparations, more intense NBT staining was observed only in rats fed a galactose diet for 22 months. In cross sections, the number of stained vessels were increased in BB rats (p < 0.01), but not in rats with streptozotocin-induced diabetes. Catalase activity did not differ between any of the experimental groups and their matched controls.

CONCLUSIONS

Increased amount of NBT reductants in retinal vessels occurred in BB Wistar rats and to some extent in galactose-fed rats, indicating a possible role for free radicals in the development of diabetic retinopathy. There was no evidence of increased retinal H2O2 production or activation of catalase, indicating that this particular enzyme was not affected during the conditions studied.

The effect of the non-ionic contrast medium iohexol on glomerular and tubular function in diabetic patients

The effect of the non-ionic contrast medium iohexol (Omnipaque) on renal function was investigated in diabetic patients with signs of peripheral ischaemia. Forty-six patients, 70 +/- 11 years (mean +/- SD) old, age at diabetes diagnosis 53 +/- 17 years, and with varying degrees of diabetic nephropathy were studied before 1, 2, and 30 days after aortobifemoral arteriography. Serum creatinine, creatinine clearance, urinary excretion of immunoglobulin G, albumin collagen IV (NC1), kappa and lambda chains, alpha-1 microglobulin and Tamm-Horsfall protein were evaluated. Within 1 month before and 30 days after arteriography, the glomerular filtration rate was measured by clearance of iohexol. The acute effect of the radiocontrast medium was an increase in the serum creatinine level in 41 (89%) patients, with a more than 25% increase in 12 (26%) patients. The excretion rates of immunoglobulin G and albumin decreased, whereas the proximal and distal tubular function and the excretion of collagen IV did not change. The increment in serum creatinine was associated with the preangiographic renal function (p < 0.05), a history of heart failure (p < 0.01), but not with age, duration and type of diabetes, gender, systolic or diastolic blood pressure, glycated haemoglobin (HbAlc) or blood glucose levels. The increase of serum creatinine was associated with a pre-existing proximal tubular dysfunction and a worsening of distal tubular function. No changes in the parameters measured persisted 30 days after angiography. In summary, a transient increment in serum creatinine level after arteriography occurred in 89% of diabetic patients. It was associated with the preangiographic renal function, a history of heart failure and signs of preexisting proximal tubular dysfunction and worsening of distal tubular function. However, these changes were reversible.

The prognostic value of albuminuria for the development of cardiovascular disease and retinopathy: a 5-year follow-up of 451 patients with type 2 diabetes mellitus

The aim of the present study was to evaluate the risk for vascular morbidity or death and retinopathy in relation to urinary albumin concentration. To that end, we performed a 5-year follow-up study of all type 2 diabetic patients attending the outpatient-clinic. A total of 444 (98.4%) out of 451 adult patients initially studied were evaluated for the degree of retinopathy and levels of HbA1c blood pressure, serum creatinine and urinary albumin. Vascular morbidity and causes of death were registered by one and the most severe event only. Forty-seven patients developed atherosclerotic vascular disease, i.e. myocardial infarction (n = 19), cerebrovascular disease (n = 20), or amputation (n = 8), and 42 died. The observed annual mortality rate was 22.1/1000 compared to an expected rate of 13.6/1000 for the general population with corresponding age and sex. Urinary albumin concentration was found to be a prognostic marker for the development of vascular disease and death in patients treated with insulin at baseline (P < 0.01), whereas this was not the case in patients treated with diet and/or oral agents at baseline. However, insulin treatment per se was not associated with an increased mortality or mortality or morbidity. Urinary albumin concentration was not correlated with incidence or progression of retinopathy regardless of type of diabetes treatment. In conclusion, this study showed that albuminuria was a prognostic factor for vascular morbidity and death in type 2 diabetic patients treated with insulin but not in patients treated with diet or oral agents. Furthermore, albuminuria was not a predictor for incidence or progression of retinopathy.

The importance of early diagnosis of treatable diabetic retinopathy for the four-year visual outcome in older-onset diabetes mellitus

The four-year visual outcome was retrospectively studied in patients with older-onset diabetes mellitus and diabetic retinopathy in need of laser treatment. Visual acuity in 53 patients examined by ophthalmologists who referred the patients for an evaluation of retinopathy before laser treatment, was compared to that of 47 patients examined by ophthalmologists who also performed the photocoagulation. The number of eyes that became blind (visual acuity < or = 6/60) during the four-year period was higher (23/90 vs 9/91; p < 0.01) among referred patients, whereas the number of retinal examinations per patient during the three-year period prior to laser treatment did not differ between the two groups. Among referred patients, 13% had not been ophthalmologically examined before the treatment-requiring retinopathy was found. Corresponding figure for those examined at the laser centre was 23%. Severe macular oedema in regularly examined patients was more common among referred patients (9/30 vs 1/32; p < 0.01). The results indicate that screening for diabetic retinopathy in older-onset diabetes was not performed satisfactorily. In addition, laser treatment was delayed in older-onset diabetic patients controlled by ophthalmologists who referred patients for photocoagulation, resulting in an increased incidence of legally blind eyes. The study also stresses the importance of carrying out knowledge of when and how to diagnose early sight-threatening diabetic retinopathy to ophthalmologists referring patients for laser treatment.

Restitution of neurophysiological functions, performance, and subjective symptoms after moderate insulin-induced hypoglycaemia in non-diabetic men

The restoration of cognitive function was studied in 10 healthy men aged 26 years (25.5 +/- 1.2 years; mean +/- SD) after insulin-induced hypoglycaemia (arterialized blood glucose 2.5 +/- 0.4 mmol l-1) for 62 +/- 8 min. Another group of six men participated in a single blind sham study for comparison. The hypoglycaemic event caused a significant increase (p = 0.006) in serum adrenaline levels. Ratings of adrenergically mediated symptoms increased during hypoglycaemia (p = 0.006), as did neuroglycopenic symptoms (p = 0.002), although neuroglycopenia ratings increased in both studies. During hypoglycaemia, P300 amplitudes in a relatively demanding visual search task decreased (p = 0.02), whereas easier tasks were unaffected. The amplitudes were restored after 40 min of normoglycaemia. Reaction time deteriorated after restoration of normoglycaemia, suggesting an effect of hypoglycaemia on learning. Thus, hypoglycaemia at a blood glucose level that is common among patients treated with insulin causes clear cognitive dysfunction, although restoration of the cognitive dysfunction to normal was fast.

Greater reduction of urinary albumin excretion in hypertensive type II diabetic patients with incipient nephropathy by lisinopril than by nifedipine

A double-blind, randomised, parallel group, multicentre, multinational study compared the effects of 12 months' treatment with lisinopril (10-20 mg once daily) or nifedipine retard tablets (20-40 mg twice daily) in 239 males (aged 18-75 years) and 96 post-menopausal females (aged 40-75 years). They all had a history of clinically stable type II diabetes > 3 months, microalbuminuria and early diabetic nephropathy (a urinary albumin excretion (UAE) rate ranging from 20 to 300 micrograms/min) and a sitting diastolic blood pressure (DBP) 90-100 mm Hg (Korotkoff phase V) inclusive at both entry and after 3-4 weeks' placebo treatment. The aim of treatment was to achieve a reduction in sitting DBP to < 90 mm Hg 24-30 h after the last dose of lisinopril or 12-18 hours after the last dose of nifedipine and to evaluate the effect of these treatments on UAE over 12 months. The effect of the two treatments on ambulatory blood pressure (BP) was also evaluated in a subset of patients. Management of diabetes with oral hypoglycaemic drugs, diet and insulin alone or in combination was permitted. Median UAE fell on lisinopril from 65.5 (range 20-297) micrograms/min at baseline to 39.0 (2-510) micrograms/min after 12 months. On nifedipine median UAE fell from 63.0 (range 20-289) micrograms/min at baseline to 58.0 (9-1192) micrograms/min after 12 months. The estimated median difference between the effects of the two treatments was 20 micrograms/min (P = 0.0006). Over 12 months both treatments produced similar falls in sitting BP from 163 +/- 17/99 +/- 6 mm Hg (mean +/- s.d.) to 147 +/- 18/88 +/- 10 mm Hg for lisinopril and from 161 +/- 18/97 +/- 5 mm Hg to 150 +/- 18/88 +/- 9 mm Hg for nifedipine. Ambulatory BP was assessed in a subset of patients and using areas under the BP-time curve (AUC) a comparison of the effects of the two treatments showed no between-treatment differences. Creatinine clearance, glycaemic control (HbA1c) and lipid profiles did not change significantly during either treatment. Frequency of withdrawals and adverse events were similar for both treatments. We conclude that lisinopril has a significantly more beneficial effect on UAE than nifedipine despite similar effects on both BP and glycaemic control in type II diabetic patients with hypertension.

Plasma beta-hexosaminidase isoenzymes A and B exhibit different relations to blood glucose levels in a population of Type 1 diabetic patients

The activity of lysosomal enzymes, such as beta-hexosaminidase (Hex), is increased in the plasma and serum of diabetic patients. A positive association has been shown between enzyme activity and glycated proteins, indicating an association with the degree of metabolic control. Several isoenzymes of Hex exist. Studies have reported different proportions of the isoenzymes in plasma from diabetic patients, compared with healthy subjects. In the present study, Hex isoenzymes were examined in 76 Type 1 diabetic patients, of mean age 37.4 years (SD 12.9) compared with 38 age- and sex-matched healthy control subjects in an attempt to evaluate the influence of long- and short-term changes in blood glucose levels on these isoenzymes. The results show that Hex A activity (p<0.01), but not Hex B activity, was higher in the diabetic patients. Hex A activity was positively associated with both the actual blood glucose levels (r = 0.48, p<0.001) and haemoglobin A1c (HbA1c) (r = 0.43, p<0.001), while Hex B activity was associated with the level of HbA1c only (r = 0.42, p<0.001). Both Hex A and B activities were also positively associated with early signs of diabetic nephropathy (e.g. urinary excretion of Hex, fractional albumin excretion ratio and urinary albumin). There was no association between Hex A and B activities and different degrees of retinopathy. In conclusion, the present study demonstrates an association between Hex A and B and metabolic parameters in diabetes as well as with clinical signs of early diabetic nephropathy, but no association with the degree of retinopathy. Furthermore, Hex A seems to be more influenced than Hex B by short-term changes in blood glucose levels.

Decreasing incidence of major amputation in diabetic patients: a consequence of a multidisciplinary foot care team approach?

The purpose of this retrospective study was to evaluate the changes in diabetes-related lower extremity amputations following the implementation of a multidisciplinary programme for prevention and treatment of diabetic foot ulcers in a 0.2 million population with a 2.4% prevalence of diabetes. All diabetes-related primary amputations from toe to hip from 1 January 1982 to 31 December 1993 were included. In 294 diabetic patients, 387 primary major (above the ankle) or minor (through or below the ankle) amputations were performed, constituting 48% of all lower extremity amputations. The annual number of amputations at all levels decreased from 38 to 21, equalling a decrease of incidence from 19.1 to 9.4/100,000 inhabitants (p = 0.001). The incidence of major amputations decreased by 78% from 16/1 to 3.6/100,000 inhabitants (p < 0.001). The absolute number of amputations with a final level below the ankle showed no increase, but their proportion increased from 28 to 53% (p < 0.001) and the reamputation rate decreased from 36 to 22% (p < 0.05) between the first and last 3-year period. Thus, a substantial long-term decrease in the incidence of major amputations was seen as well as a decrease in the total incidence of amputations in diabetic patients. Seventy-one per cent of the amputations were precipitated by a foot ulcer. These findings indicate that a multidisciplinary approach plays an important role to reduce and maintain a low incidence of major amputations in diabetic patients.

The cerebral vascular response to a rapid decrease in blood glucose to values above normal in poorly controlled type 1 (insulin-dependent) diabetes mellitus

The effect of rapid lowering of blood glucose on cerebral blood flow (CBF) was studied in 10 Type 1 (insulin-dependent) diabetic patients (age 23.5 +/- 3.8 years; mean +/- S.D.) with longstanding, poor metabolic control (HbAlc 11.2 +/- 1.0%; normal value 4.0-5.3%) using an intravenous xenon 133 single photon emission computed tomography technique. After a fall in blood glucose, during 81 +/- 11 min (mean +/- S.E.M.), from 18.2 +/- 1.4 mmol/l to 9.2 +/- 0.9 mmol/l CBF was unchanged, but increased from its initial value of 48.8 +/- 2.9 ml/100 g per min to 57.1 +/- 2.4 ml/100 g per min (P < 0.001) when the blood glucose level was restored. The CBF was higher in the right compared to the left hemisphere at all measurements (1.8 +/- 0.5 ml/100 g per min, P < 0.01; 1.9 +/- 0.5 ml/100 g per min, P < 0.05; 2.1 +/- 0.7 ml/100 g per min, P < 0.05, respectively). The change in CBF was inversely correlated with time for fall of blood glucose, but there was no correlation with absolute levels of blood glucose. The respiratory end-tidal PCO2 decreased during the low blood glucose level, but there was no correlation between the PCO2 and CBF. The cerebral volume was unchanged during the study. The results indicate that in patients with chronic hyperglycemia a rapid fall in blood glucose may cause a rise in CBF of the same magnitude as previously shown during absolute hypoglycemia in patients with well controlled diabetes mellitus and in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical characteristics in relation to final amputation level in diabetic patients with foot ulcers: a prospective study of healing below or above the ankle in 187 patients

The aim of this study was to describe the clinical characteristics in relation to final amputation level in diabetic patients with foot ulcers. In a prospective series, 187 consecutively presenting patients were investigated. From admission until final outcome, the patients were treated by a multidisciplinary team both as in- and out-patients. All the patients had one or more signs of neuropathy and 171 had evidence of peripheral vascular disease. Healing with an amputation below the ankle occurred in 74 patients, 88 patients healed with an amputation above the ankle, and 25 patients died unhealed. Amputation above the ankle was associated with high age, living in an institution, a limited walking capacity, cerebrovascular disease, congestive heart failure, and a low hemoglobin level. Amputation below the ankle was associated with diabetes diagnosis before 30 years of age and diabetes duration. In conclusion, older age, history of cerebrovascular disease and low hemoglobin level are associated with above ankle amputation level in diabetic patients with foot ulcers. However, level selection cannot be based upon these factors only, since some patients at high age, with cerebrovascular disease or with a low hemoglobin value, healed with an amputation below the ankle. None of these factors per se should be taken as a cause to choose a primary amputation above the ankle, unless amputation is supported by the total clinical picture, including local characteristics, such as type and localization of ulcer, and signs of peripheral vascular disease. More attention should be paid to biological than to chronological age.

Increased catalase levels and hypoxanthine-enhanced nitro-blue tetrazolium staining in rat retina after ischemia followed by recirculation

In the present study, using retinal ischemia as a model, we examined if different periods of ischemia and recirculation influenced the generation of reactive oxygen species, i.e. in hydrogen peroxide generation and nitroblue tetrazolium (NBT) reduction. Ischemia was induced for 30 and 90 min by ligation of the optic nerve with the vessels and recirculation was established by removing the ligature. The rats were sacrificed after 15 min or 3 days of recirculation. The retinas were separated from the pigment epithelium for measurements of catalase activity and examination of NBT staining. Compared to controls, the catalase activity was increased after 30 and 90 min of ischemia followed by 15 min of recirculation, and after 90 min of ischemia followed by 3 days of recirculation. As in controls, NBT staining was observed, both after 30 and 90 min of ischemia followed by 15 min of recirculation, in photoreceptors, in both plexiform layers, in some ganglion and glial cells, and, occasionally, in cells in the inner nuclear layer. Opposite to controls, addition of hypoxanthine to the NBT solution resulted in an increased staining in vessels in the inner nuclear layer in retinas subjected to 30 min of ischemia followed by 3 days of recirculation. The increased catalase activity suggests an increased amount of this free radical scavenger after ischemia followed by short-term and long-term recirculation. The hypoxanthine-enhanced NBT staining of blood vessel walls after ischemia followed by long-term recirculation indicates an activation of xanthine oxidase and an increased production of NBT reductants, some of which may represent oxygen free radicals.

Lack of association between plasma homocysteine levels and microangiopathy in type 1 diabetes mellitus

The reactive vascular-injuring amino acid homocysteine was previously shown to be increased in plasma in diabetic patients with clinical signs of nephropathy. In this study, plasma homocysteine was measured in type 1 diabetic patients with normoalbuminuria (n = 22), microalbuminuria (n = 40) and proteinuria (n = 14) in order to investigate whether plasma homocysteine levels are increased already at the stage of incipient nephropathy, i.e. microalbuminuria. Furthermore, patients were characterized according to the degree of retinopathy. Plasma homocysteine in the whole population (n = 76) was related to B-Folate (r = 0.38, p < 0.01), S-Creatinine (r = 0.55, p < 0.001), S-Urea (r = 0.37, p < 0.01), U-Albumin (r = 0.46, p < 0.001), urinary N-acetyl-beta- glucosaminidase (r = 0.40, p < 0.001), systolic blood pressure (r = 0.36, p < 0.01) and diabetes duration (r = 0.44, p < 0.001). There were no differences in plasma homocysteine levels between patients with normoalbuminuria (8.0 +/- 1.7 mumol l-1; mean +/- SD) and those with microalbuminuria (9.1 +/- 3.4 mumol l-1). However, patients with clinical signs of nephropathy had higher plasma homocysteine levels (12.9 +/- 5.7 mumol l-1, p < 0.01) compared to the other two groups. There was no association between plasma homocysteine levels and different degrees of retinopathy. Thus, the present study does not show any relation between plasma homocysteine levels and early stages of diabetic nephropathy or retinopathy indicating that elevated concentrations of plasma homocysteine does not explain the increased risk for atherosclerosis observed in patients with microalbuminuria.

Influence of intensified insulin regimen on quality of life and metabolic control in insulin-dependent diabetes mellitus

Seventy-eight non-randomized patients with IDDM, aged 33.8 +/- 9.6 years (mean +/- S.D.), with a duration of diabetes of 16.6 +/- 9.5 years and a HbA1c level of 8.0% +/- 1.5 at baseline were included in the study. The effects of a change from a 3-dose insulin regimen using conventional syringes to a treatment mode using 4 injections per day with a pen injector on metabolic control, perceived distress from diabetes on everyday life and correspondence between expectations and experiences of treatment during a 1-year trial were assessed. The experience measures were registered at baseline and after 3 and 12 months, respectively. HbA1c levels were measured every 3 months. Neither the metabolic control nor the body mass index or rate of hypoglycemic episodes changed during the study period. However, the patients experienced a decreased distress from diabetes, which appeared during the first 3 months and remained unchanged thereafter. The expectations of advantages from the intensified insulin therapy were generally high and were mostly either fulfilled or exceeded by experiences. We conclude that multiple insulin injection therapy, under routine treatment conditions, is subjectively preferable to patients and has favourable effects on their quality of life although something more is required in order to also achieve an improvement of metabolic control.

Local signs and symptoms in relation to final amputation level in diabetic patients. A prospective study of 187 patients with foot ulcers

Local signs and symptoms were evaluated in 187 consecutively presenting diabetic patients undergoing amputation for foot ulcers. From admission until final outcome the patients were treated by the same multidisciplinary team both as in- and out-patients. At the time of amputation, the types of lesions were superficial/deep ulcer (n 17), ulcer with deep infection, but without gangrene (n 40), and gangrene with or without infection (n 130). Healing after a minor amputation (below the ankle) occurred in 74 patients, while 88 patients healed after a major amputation (above the ankle), and 25 patients died before healing had occurred. Deep infection and presence of popliteal or pedal pulses were associated with healing after minor amputation and so were ulcers on the small toes, metatarsal head area and midfoot. Pain, progressive gangrene, intermittent claudication, and decubital and multiple ulcers were related to healing after major amputation. In a logistic regression analysis, pain, progressive gangrene and intermittent claudication remained. However, none of these factors excluded healing of a minor amputation and thus selection of amputation level in diabetic patients with foot ulcers cannot be based upon these factors exclusively.

Nitro blue tetrazolium staining and hydrogen peroxide production in the rat retina in vitamin E deficiency and after light exposure

Nitro blue tetrazolium (NBT) staining in normal rat retina was previously found to be affected by inhibition of free radical-related enzyme systems, indicating that NBT might be useful as a marker of free radicals. The aim of the present study was to investigate NBT staining in rat retina in vitamin E deficiency and after blue light exposure, and also to measure hydrogen peroxide (H2O2) production indirectly by measuring catalase activity under these conditions. Vitamin E deficiency resulted in morphological changes in the retina and increased NBT staining in the photoreceptors and in the outer plexiform layer. Light exposure caused increased staining in the inner segments of photoreceptors. The increased staining was not clearly influenced by addition of the free radical scavengers superoxide dismutase and catalase. The catalase activity was not influenced by light exposure, while it was increased in vitamin E-deficient retina compared to controls. The results indicate that reducing systems as measured by NBT were activated in the retina under these conditions. However, to what extent the reductants represent free radicals still has to be established using other methods.

Urinary excretion rate of NC1 and Tamm-Horsfall protein in the microalbuminuric type I diabetic patient

Fifty-six type I diabetic patients with microalbuminuria (albumin excretion rate 20-200 micrograms/min) were characterized as to sex, age, duration of diabetes, smoking habits, blood pressure, glomerular filtration rate, urinary NC1 (the carboxy-terminal domain of collagen IV), and Tamm-Horsfall protein excretion rate. Albumin excretion rate was considered a sign of glomerular damage, NC1 excretion rate a measure of renal basement membrane turnover, and Tamm-Horsfall protein excretion rate a marker for distal tubular function. There were no differences between males and females and between smokers and nonsmokers with respect to blood pressure, body-mass index, albumin excretion rate, glomerular filtration rate, excretion rate of NC1, and Tamm-Horsfall protein. As a group, the patients with microalbuminuria had normal glomerular filtration rate, excretion rate of NC1, and Tamm-Horsfall protein. The latter was influenced by glycosylated hemoglobin (HbA1c) levels, especially so in patients with an albumin excretion rate less than the median value of 53.0 micrograms/min (r = -0.61, p < 0.01). Furthermore, both excretion rate of NC1 and Tamm-Horsfall protein were increased in patients with high glomerular filtration rate > or = 130 mL min-1 1.73 m-2). There was no association between glomerular filtration rate and HbA1c levels. As glomerular filtration rate is related to kidney size, these observations suggest that patients with a high glomerular filtration rate have an increased mass and turnover of tubular basement membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

A four-year follow-up study on the incidence of diabetic retinopathy in older onset diabetes mellitus

Out of 369 diabetic patients with an age at onset of diabetes > or = 30 years previously studied, 325 (88%) were included in an ophthalmological follow-up examination 4 years later. In patients treated with oral drugs at baseline, the incidence of any type of retinopathy was 30.8% and of severe retinopathy 5.7%. All patients who developed severe retinopathy received insulin during the follow-up period. At baseline, duration of diabetes, diastolic blood pressure, and signs of nephropathy (p < 0.05 in all cases) as well as degree of metabolic control (p < 0.01) differed between patients who developed retinopathy and those who did not. At follow-up, there were no longer any differences regarding degree of metabolic control and diastolic blood pressure. In patients treated with insulin at baseline, the incidence of any type of retinopathy was 41.0% and of severe retinopathy 16.1%. At baseline, duration of diabetes (p < 0.01), degree of metabolic control, and insulin dosage (p < 0.05 in both cases) differed between patients who developed retinopathy and those who did not. At follow-up, there was no longer any difference in insulin dosage.

A 5-year follow-up study on the incidence of retinopathy in type 1 diabetes mellitus in relation to medical risk indicators

OBJECTIVES

The aim of the present study was to describe the 5-year incidence of retinopathy in type 1 diabetes mellitus and to characterize risk indicators for the development and progression of retinopathy.

DESIGN

A cross-sectional study of type 1 diabetic patients taken care of at a medical department.

SETTING

All type 1 diabetic patients attending the Department of Internal Medicine, University Hospital, Lund, during a 2-year period were offered ophthalmological examination.

SUBJECTS

A total of 396 out of 461 (85.9%) initially examined type 1 diabetic patients formed the basis for this 5-year follow-up study.

MAIN OUTCOME MEASURES

The degree of retinopathy was based on fundus photography or biomicroscopy. Degree of metabolic control was assessed by HbA1c levels, signs of nephropathy by albumin creatinine clearance ratio and urinary albumin levels. Blood pressure was measured in the supine position. Duration of diabetes, age, and insulin dosage were registered.

RESULTS

The incidence of retinopathy was 47.2% and progression from background to severe retinopathy occurred in 41%. Risk indicators for the development of retinopathy were duration of diabetes (P < 0.001), degree of metabolic control (P < 0.001), insulin dosage (P < 0.05) and signs of nephropathy based on measurements of albumin creatinine clearance ratio (P < 0.01) and urinary albumin concentration (P < 0.05). Two risk indicators could be identified for progression of retinopathy, i.e. the degree of metabolic control (P < 0.01) and diastolic blood pressure (P < 0.05).

CONCLUSIONS

The results suggest that apart from poor metabolic control, development of retinopathy in type 1 diabetes is associated with long diabetes duration and clinical signs of diabetic nephropathy. Progression of retinopathy is associated with poor metabolic control and elevated diastolic blood pressure levels.

The five-year incidence of blindness after introducing a screening programme for early detection of treatable diabetic retinopathy

The incidence of moderate visual impairment and blindness due to diabetic retinopathy was studied 5 years after introducing a screening system for early detection of treatable retinopathy. Photocoagulation was performed in patients with clinically significant macular oedema, severe preproliferative, and proliferative retinopathy. Eighty-eight percent of 470 Type 1 and 88% of 388 Type 2 diabetic patients were still available for follow-up. In the Type 1 group, the five-year incidence of blindness and moderate visual impairment were 0.5% and 1.2%, respectively. Corresponding figures for the Type 2 diabetic patients were 0.6% and 1.7%, respectively. The majority of patients with loss of vision had severe retinopathy at baseline. Among those who entered the screening programme with no or mild retinopathy, loss of vision occurred in only one of the Type 1 and four of the Type 2 diabetic patients. It is concluded that the risk for visual impairment and blindness due to diabetes can be substantially reduced by using programmes for early detection of and effective treatment of diabetic retinopathy.

Distal blood pressure as a predictor for the level of amputation in diabetic patients with foot ulcer

The predictive value of distal blood pressure measurements for the level of amputation was studied prospectively in 161 consecutive diabetic patients with foot ulcers. The patients were treated as outpatients except for periods of surgery and when complications requiring hospital care occurred. All patients were treated pre- and postoperatively by the same multidisciplinary foot care team. Either ankle or toe blood pressure measurement was available in 86% of the patients. Incompressible arteries, ulcer or gangrene at the measuring site, previous amputation, poor general condition, and an emergency situation were factors that excluded standardized ankle and toe blood pressure measurements in 24% and 27% of the patients, respectively. An absolute lower ankle pressure level of 50 mm Hg was found, below which a minor amputation was never sufficient to achieve healing. An ankle pressure below 75 mm Hg was seldom sufficient, and at or above that pressure level, the ankle pressure had no predictive value in this respect. At a toe pressure below 15 mm Hg, a minor amputation was seldom sufficient. Ankle and toe pressure indices gave no further information.

Long-term prognosis for diabetic patients with foot ulcers

OBJECTIVE

To evaluate the recurrence of foot ulcers as well as the cumulative amputation and mortality rates in diabetic patients with previous foot ulcers.

DESIGN

A prospective study of consecutively presenting diabetic patients admitted to the Department of Internal Medicine because of foot ulcer with a median follow-up of 4 years.

SETTING

A multidisciplinary foot-care team.

POPULATION

Five-hundred-and-fifty-eight consecutive diabetic patients with foot ulcers treated between 1 July 1983 and 31 December 1990 were followed to final outcome. Out of these patients, 468 healed either primarily (n = 345) or after minor or major amputations (n = 123) and 90 died before healing had occurred. Those 468 patients who healed were included in this prospective study from the time of healing.

MAIN OUTCOME MEASURES

Patients were followed according to a standardized protocol with registration of foot lesions, amputation, morbidity and mortality. Clinical examination was performed twice yearly.

RESULTS

After 1, 3 and 5 years of observation 34%, 61% and 70% of the patients, respectively, had developed a new foot ulcer. The recurrence rate of foot lesions was slightly higher among patients who previously had had an amputation (P < 0.05, P < 0.01 and non-significant, respectively). Among patients with previous primary healing the cumulative amputation rates were 3%, 10% and 12% after 1, 3 and 5 years of follow-up compared with 13%, 35% and 48% among those who previously healed after amputation, irrespective of previous amputation level (P < 0.001 at all time-points). All amputations except three were initiated by a foot ulcer deteriorating to deep infection or progressive gangrene. The long-term survival ratio was lower among patients healed after previous amputation (80%, 59%, 27%) compared with patients with previously primary healing (92%, 73%, 58%) after 1, 3 and 5 years of observation, respectively (P < 0.001, P < 0.01 and P < 0.001 respectively). The mortality rate was twice as high among primarily healed and four times as high among patients with amputation compared to an age- and sex-matched Swedish population.

CONCLUSION

These findings stress the need for life-long surveillance of the diabetic foot at risk and the necessity of preventive foot care among diabetic patients with previous foot lesions, and particularly among those who had had a previous amputation.

The influence of hypoglycaemia on regional cerebral blood flow and cerebral volume in type 1 (insulin-dependent) diabetes mellitus

The effect of moderate hypoglycaemia (venous blood glucose 2.0 +/- 0.2 mmol/l; mean +/- SD) on regional cerebral blood flow and cerebral volume was studied in a group of ten right-handed patients with Type 1 (insulin-dependent) diabetes mellitus (age 26.0 +/- 2.4 years, duration 18.4 +/- 3.8 years) using an intravenous Xenon 133 single photon emission computed tomography technique. After 10 min of hypoglycaemia, global cerebral blood flow had increased to 55.8 +/- 4.5 ml.100 g-1.min-1 compared to the initial normoglycaemic flow of 49.5 +/- 3.7 ml.100 g-1.min-1 (p < 0.01). A further increase in global cerebral blood flow to 59.5 +/- 4.5 ml.100 g-1.min-1 (p < 0.05) occurred 15 min after normalization of the blood glucose level. The global cerebral blood flow change from before hypoglycaemia to after recovery was inversely related to the initial glucose level. No change in the relative distribution of the regional cerebral blood flow was found between the measurements. The cerebral blood flow was significantly higher in the right hemisphere compared with the left hemisphere (2.3, 1.6 and 2.2%, respectively; p < 0.05) in all measurements. Deeper hypoglycemia was associated with a more pronounced decrease in brain volume, while the length of the restitution time after hypoglycaemia correlated with a volume increase. Due to influences with opposite effects there was no mean change in the brain volume.

Nitro blue tetrazolium staining: a morphological demonstration of superoxide in the rat retina

Nitro blue tetrazolium (NBT) is an artificial electron acceptor which has been suggested to be a useful tool in studies of free radicals. To establish whether NBT could be useful in morphological demonstration of free radicals in the retina, the staining pattern was examined in normal rat retina and after incubation with the free radical scavenger superoxide dismutase or with inhibitors of free radical protective enzymes, such as potassium cyanide, dicoumarol, and aminotriazole. After 60 min incubation in 1 mM NBT, staining was observed in photoreceptors, in some cells in the inner nuclear and ganglion cell layers, and in glial cells. Staining also appeared in the plexiform layers and occasionally in small blood vessels. Addition of superoxide dismutase caused a decreased staining of the inner parts of the retina. The inhibitors of free radical scavengers caused a dose-dependent increase in staining of the inner parts of the retina and, at high concentrations of potassium cyanide, of the photoreceptors. Thus, NBT seems indeed to be useful in morphological studies of free radicals in the retina.

Day and night variation in ambulatory blood pressure in type 1 diabetes mellitus with nephropathy and autonomic neuropathy

The objective was to study ambulatory blood pressure and heart rate variability between day and night in patients with type 1 (insulin-dependent) diabetes mellitus with different degrees of diabetic nephropathy, and to evaluate the influence of autonomic neuropathy and type of antihypertensive treatment. Twenty type 1 diabetic patients with diabetic nephropathy and antihypertensive treatment were studied with 24-h ambulatory blood pressure monitoring using an oscillometric method. They were compared with eight insulin-treated diabetic patients with short duration of diabetes (1-5 years) and with 10 apparently healthy subjects. The degree of autonomic neuropathy was evaluated by measuring the RR-interval during deep breathing and uprising. The 24-h blood pressure was generally higher in patients with diabetic nephropathy compared to those other two groups. These patients also had a lower ratio between day and night in diastolic blood pressure compared to the control subjects (1.15 +/- 0.12 vs. 1.25 +/- 0.76, P < 0.05) and heart rate compared to the diabetic patients without nephropathy, as well as the control subjects (1.15 +/- 0.08 vs. 1.26 +/- 0.09 vs. 1.27 +/- 0.08, P < 0.01, respectively). All patients with diabetic nephropathy had clinical signs of autonomic neuropathy as judged by RR-interval measurements during deep breathing and uprising.

The predictive value of albuminuria for cardiovascular and renal disease. A 5-year follow-up study of 476 patients with type I diabetes mellitus

A 5-year follow-up study of 476 type I adult diabetic patients previously studied cross sectionally revealed that, during the observation period, 19 patients died and 30 developed cardiovascular or renal disease, such as myocardial infarction (n = 8), cerebrovascular disease (n = 3), amputation (n = 6), and renal insufficiency (n = 13). The patients were registered by one and the most-severe event only. The yearly death rate was 8.0 per 1000, compared with the expected death rate of 2.0 for people with corresponding age and sex in the general population. In patients with renal insufficiency, one also had myocardial infarction, and one had had an amputation. The ages of patients who died, with myocardial infarction, cerebrovascular disease, amputation, or renal insufficiency, were 44.2 +/- 12.7, 41.3 +/- 6.6, 43.7 +/- 13.2, 45.3 +/- 15.7, and 40.8 +/- 9.8 years, respectively. Urinary albumin concentration in a single early morning urine sample was found to be a strong prognostic marker for the development of cardiovascular disease or death. In contrast, age, gender, age at onset and duration of diabetes, levels of blood pressure, serum creatinine, and HbA1c, or presence of hypertension, as well as changes in blood pressure and hBa1c, during the observation period did not influence the survival or incidence of cardiovascular disease. However, blood pressure and HbA1c were associated with increased urinary albumin concentrations during the follow-up period.

Tubular secretion of Tamm-Horsfall protein is decreased in type 1 (insulin-dependent) diabetic patients with diabetic nephropathy

Signs of glomerular, proximal and distal tubular dysfunction as well as metabolic control were studied in type 1 diabetes mellitus. To that end, the urinary excretion rates of albumin, sodium, phosphate and Tamm-Horsfall protein as well as HbA1c levels were measured in 20 patients with different degrees of diabetic nephropathy (positive Albustix for several years). Eight diabetic patients with short duration of diabetes and without any diabetic complications and 10 apparently healthy subjects were studied for comparison. The HbA1c levels in the three groups were 8.6 +/- 1.2, 5.9 +/- 2.2 and 4.1 +/- 0.4%, respectively (mean +/- SD). Duration of diabetes in the two diabetic groups were 27 +/- 7 and 3 +/- 1 years, respectively. The urinary protein levels were measured by enzyme-linked immunoassays. The fractional clearance of sodium (1.9 +/- 1.9%; p < 0.001) and phosphate (27 +/- 11%; p < 0.01) were increased in patients with diabetic nephropathy compared to diabetic patients without nephropathy (0.6 +/- 0.2 and 16 +/- 4%) and healthy control subjects (0.6 +/- 0.1 and 16 +/- 4%, respectively). Tamm-Horsfall protein excretion rate was decreased in both diabetic groups (15.0x/3.1 and 37.9x/1.9 micrograms/min, geometric mean x/tolerance factor, p < 0.001 and p < 0.05, respectively) compared to the healthy subjects (63.8x/1.3 micrograms/min). Furthermore, patients with diabetic nephropathy had a lower excretion rate of Tamm-Horsfall protein (15.0x/3.1 micrograms/min) compared to patients without signs of nephropathy (37.9x/1.9 micrograms/min, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The association between clinical risk factors and outcome of diabetic foot ulcers

OBJECTIVE

The aim of the study was to describe the association between clinical risk factors in diabetic patients with food ulcers in relation to outcome.

DESIGN

A prospective study of 314 consecutively presenting diabetic patients with foot ulcers referred to the Department of Internal Medicine between July 1, 1983 and June 30, 1987. All patients were followed to final outcome.

SETTING

All patients were treated by the same multi-disciplinary foot care team at the Department of Medicine, both as in- and out-patients. Healing was defined as intact skin for at least 6 months.

RESULTS

One hundred and ninety-seven patients healed primarily, 77 after amputation, and 40 died unhealed. Signs of macroangiopathy were more common among patients who healed after amputation. The outcome was strongly related to age, though 43% of the patients with an age over 80 years healed primarily. There was no difference in smoking habits between patients who healed primarily and those who required amputation to heal. Diabetic nephropathy was found in 26% of the patients and was strongly associated with amputation. Presence of retinopathy was found in 54% of the patients, but this finding was not related to the outcome. There were no differences in short-term metabolic control as assessed by hemoglobin A1c levels between patients who healed primarily and those who healed after amputation.

CONCLUSION

The presence of diabetic foot ulcers was strongly associated with age and diabetic complications such as multiple cardiovascular disease and nephropathy, which were important factors related to amputation.

Medical risk factors in diabetic patients with foot ulcers and severe peripheral vascular disease and their influence on outcome

The association between medical risk factors and the outcome of foot ulcers was evaluated in 208 consecutive diabetic patients with severe peripheral vascular disease (systolic toe blood pressure < or = 45 mm Hg). All patients were treated and followed by the same foot care team. Eighty patients healed primarily, 83 healed after a minor or major amputation, and 45 died. The systolic toe blood pressure was higher among primary healed (30 +/- 13 mm Hg) compared with amputated (22 +/- 15 mm Hg; p < 0.001) and deceased patients (20 +/- 14 mm Hg; p < 0.001). The patients were comparable regarding age, sex, and diabetes and wound duration. Only 41 (19%) patients had intermitten claudication, whereas 153 (77%) lacked palapble pedal pulses, 36% of whom healed primarily. Rest pain occurred in 72 (33%) patients, 38 (47%) of whom had an amputation and 18 (25%) who healed primarily (p < 0.01). Peripheral edema and proteinuria were more common among patients who healed after amputation compared with those who healed primarily (p < 0.001 and p < 0.01, respectively). Signs of sensory neuropathy were found in 158 (77%) patients. There were no differences concerning cardiovascular disease, smoking habits, or short-term metabolic control between patients who healed primarily or after an amputation. In conclusion, diabetic patients with foot ulcers and severe peripheral vascular disease with low systolic toe blood pressure were not excluded from the possibility of primary healing. The most important risk factors for amputation were a systolic toe pressure of less than 30 mm Hg, peripheral edema, rest pain, and proteinuria.

Regional cerebral blood flow in normal man during insulin-induced hypoglycemia and in the recovery period following glucose infusion

The effect of moderate hypoglycemia (p-glucose, 2.0 +/- 0.3 mmol/L; mean +/- SD) on regional cerebral blood flow (rCBF) was studied in a group of 10 healthy, right-handed men (aged 23 to 28 years) using an intravenous xenon 133 single photon emission computed tomography technique (SPECT). After 10 minutes of hypoglycemia, global CBF had increased to 46.3 +/- 9.6 mL/100 g/min compared with the initial normoglycemic flow of 38.6 +/- 6.8 mL/100 g/min (P less than .01). The relative distribution of the rCBF changed significantly (P less than .05, ANOVA) from before to during hypoglycemia. Of the 10 regions analyzed, the highest increments in rCBF during hypoglycemia were found in the frontal (21.5% +/- 15.2%) and parietal (20.6% +/- 14.2%) lobes, and the lowest (10.7% +/- 9.4%) were found in the pons/brainstem regions. The increase in rCBF persisted for 15 minutes after normalization of blood glucose. The persisting high flow after hypoglycemia affected all regions, but a further 10.1% +/- 7.2% increase was observed in the pons/brainstem area (P less than .05). The CBF was significantly higher in the right compared with the left hemisphere (2.8%, 1.2%, and 3.9%, respectively; P less than .05) in all measurements. A decrease in brain volume was found at the final examination, compared with the hypoglycemic state (2.6%; P less than .05). It is concluded that moderate hypoglycemia leads to a marked increase in CBF and in the relative distribution of rCBF, which persists in the immediate period after normalization of the blood glucose level.

Irreversible progression of severe retinopathy in young type I insulin-dependent diabetes mellitus patients after improved metabolic control

The impact of metabolic control on the development of rapidly progressive severe retinopathy was studied in 14 young type I insulin-dependent diabetes mellitus (IDDM) patients. Glycosylated hemoglobin (HbAlc) levels 45 months prior to and 12 months after the diagnosis of retinopathy were compared with HbAlc levels in 17 type I IDDM patients with no or minimal background retinopathy, matched for age and duration of diabetes. HbAlc levels were generally higher in patients with severe retinopathy (p less than 0.05) from 39 months until 6 months before the diagnosis of retinopathy. Thereafter, there was a gradual decrease in HbAlc levels reaching the same level as in control patients 6 months after diagnosis of retinopathy. Patients with severe retinopathy required higher doses of insulin prior to the diagnosis of retinopathy (p less than 0.05), but the insulin requirement decreased, and 12 months afterward, the insulin dosage was similar to patients with background retinopathy. Systolic blood pressure levels were slightly increased and higher in patients with severe retinopathy compared with control patients from 18 months before to diagnosis of retinopathy (p less than 0.05). Diastolic blood pressure levels likewise differed at 18 and 12 months before and at the time of diagnosis of retinopathy as well as 12 months afterward (p less than 0.05); however, no differences were seen in urinary albumin or serum creatinine levels between the groups. Thus, years of poor metabolic control, drastically improved, preceded the development of irreversible severe retinopathy in these young type I IDDM patients.

Neuropsychological performance differs between type 1 diabetic and normal men during insulin-induced hypoglycaemia

Cerebral function was measured with a neuropsychological test battery before, during, and after insulin-induced hypoglycaemia (blood glucose approximately 2.0 mmol l-1) in 10 male Type 1 diabetic patients (age 20-43 years, duration of diabetes 14 (2-30) years) and in 12 normal men. There were no group differences in neuropsychological results at normal glucose levels. Significant effects of hypoglycaemia were found in reaction-time measures (p less than 0.001) and in other tests requiring speed and attention (p less than 0.001), in verbal fluency (p less than 0.05), and short-term memory (p less than 0.001). Significant group effects and interactions (p less than 0.05) revealed that the diabetic patients were generally more affected by hypoglycaemia than the normal subjects. This might have been partly due to the larger absolute decrease in blood glucose level in the diabetic patients, although the rate of glucose decrease was not related to performance in either group. Thus, the diabetic brain might be more vulnerable to hypoglycaemia, perhaps through the persistent impact of repeated hypoglycaemic episodes, although no neuropsychological deficit is demonstrable at normal blood glucose levels.

Growth hormone levels in the basal state and after thyrotropin-releasing hormone stimulation in young type 1 (insulin-dependent) diabetic patients with severe retinopathy

Sixteen young patients with type 1 diabetes mellitus and rapidly progressive severe retinopathy were examined regarding serum levels of growth hormone before and after the i.v. administration of 200 micrograms thyrotropin-releasing hormone (TRH). Serum IGF I, HbA1c, blood pressure, urinary albumin, and serum creatinine levels were also measured. The control group consisted of type 1 diabetic patients matched for age, duration of diabetes and metabolic control with no or minimal background retinopathy. The results show that basal growth hormone levels were above normal in both groups, and that there was a paradoxical increment in growth hormone levels after TRH stimulation (p < 0.05) in patients with severe retinopathy, but the values did not differ from patients with background retinopathy. IGD I levels were normal in all patients but one, and no differences were seen between the two groups. HbA1c, serum creatine, blood pressure, and urinary albumin levels were similar in the groups but patients with severe retinopathy were treated with more insulin (p < 0.001). Thus, neither abnormal growth hormone levels, nor IGF I, seems to be associated with the development of severe retinopathy in young type 1 diabetic patients.

Tubular secretion of Tamm-Horsfall protein in type 1 (insulin-dependent) diabetes mellitus using a simplified enzyme linked immunoassay

The relationship between glomerular and tubular dysfunction and metabolic control in type 1 diabetes was studied. To that end the urinary excretion rates of albumin and Tamm-Horsfall protein as well as HbA1c levels were measured in 58 patients with different degrees of diabetic nephropathy and in 76 apparently healthy subjects matched for sex and age. The urinary Tamm-Horsfall protein levels were measured by a simplified enzyme linked immunoassay. The intra- and interassay variations were 8.9% and 13.6%, respectively. The intraindividual variation was 41% and the sensitivity of the assay was 4 micrograms/l. The Tamm-Horsfall protein excretion rate was 42.1 x/2.0 micrograms/min (geometric mean x/tolerance factor) in the diabetic patients compared to 34 x/1.9 micrograms/min in the control subjects (NS). The diabetic patients had higher albumin excretion rate (38.5 x/7.3 micrograms/min) than the control subjects (4.7 x/2.3 micrograms/min; P less than 0.001). By using multivariate analysis of variance, HbA1c level was found to be the only independent variable associated with Tamm-Horsfall protein excretion rate in diabetic patients (r = -0.28; P = 0.04), while no relationship was found between Tamm-Horsfall protein excretion rate and age, age at onset and duration of diabetes, gender, serum creatinine, diuresis, urinary albumin excretion rate, systolic and diastolic blood pressure levels and antihypertensive treatment. The urinary albumin excretion rate was associated with diastolic blood pressure (r = 0.34; P = 0.02) but not with HbA1c levels when testing the above variables by multivariate analysis of variance. In conclusion, these results may indicate a lack of relationship between glomerular and tubular dysfunction. The former was influenced only by diastolic blood pressure levels and the latter only by the degree of metabolic control. However, the correlations were weak and do not provide any insight into what is actually responsible for glomerular and tubular dysfunction.

The influence of hypothermia on hypoglycemia-induced brain damage in the rat

The effects of hypothermia on hypoglycemic brain damage were studied in rats after a 30-min period of hypoglycemic coma, defined as cessation of spontaneous EEG activity. The rats were either normothermic (37 degrees C) or moderately hypothermic (33 degrees C). Morphological brain damage was evaluated after various periods of recovery. Hypothermic animals with halothane anesthesia never resumed spontaneous respiration, thus requiring artificial ventilation during recovery (maximally 8 h). In contrast, when isoflurane was used as the anesthetic agent, all animals survived and were examined after 1 week of recovery. There was a tendency towards gradually higher arterial plasma glucose levels during hypoglycemia with lower body temperature. The time period from insulin injection until isoelectric EEG appeared was gradually prolonged by hypothermia, and was shorter when isoflurane was used for anesthesia. Brain damage was examined within the neocortex, caudoputamen and hippocampus (CA1, subiculum and the tip of the dentate gyrus). Damage to neurons was found to be of two types, namely condensed dark purple neurons (pre-acidophilic) and shrunken bright red-staining neurons (acidophilic). In the neocortex, no clear influence of temperature on the degree of injury was seen. In the caudoputamen, the number of injured neurons clearly decreased at lower temperature (33 degrees C, P less than 0.001) when halothane was used, while no such difference was seen when isoflurane was used as the anesthetic agent. Likewise, a protective effect of hypothermia was seen in subiculum (P less than 0.01) when halothane, but not isoflurane was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Association between urinary N-acetyl-beta-glucosaminidase and its isoenzyme patterns and microangiopathy in type 1 diabetes mellitus

Urinary N-acetyl-beta-glucosaminidase (NAG) and its isoenzymes (NAG A and NAG B) in samples from 87 type 1 diabetic patients and 40 apparently healthy reference subjects were studied with enzyme immunoassays. The diabetic patients had higher concentrations of urinary NAG than did the control subjects (P less than 0.01), but the isoenzyme pattern did not differ. There was a positive correlation between metabolic control (Hb A1c concentrations) and total NAG (P less than 0.01), NAG A (P less than 0.01), and NAG B (P less than 0.001). The diabetic patients were divided into three groups, depending on the degree of retinopathy. Subjects with severe forms of retinopathy did not have increased concentrations of urinary NAG unless they had concomitant nephropathy. The isoenzyme pattern was similar irrespective of degree of retinopathy or nephropathy. The results indicate that concentrations of urinary NAG are positively correlated to the degree of nephropathy, whereas there is no such correlation to the degree of retinopathy.

Association between urinary N-acetyl-beta-glucosaminidase and its isoenzyme patterns and microangiopathy in type 1 diabetes mellitus

Urinary N-acetyl-beta-glucosaminidase (NAG) and its isoenzymes (NAG A and NAG B) in samples from 87 type 1 diabetic patients and 40 apparently healthy reference subjects were studied with enzyme immunoassays. The diabetic patients had higher concentrations of urinary NAG than did the control subjects (P less than 0.01), but the isoenzyme pattern did not differ. There was a positive correlation between metabolic control (Hb A1c concentrations) and total NAG (P less than 0.01), NAG A (P less than 0.01), and NAG B (P less than 0.001). The diabetic patients were divided into three groups, depending on the degree of retinopathy. Subjects with severe forms of retinopathy did not have increased concentrations of urinary NAG unless they had concomitant nephropathy. The isoenzyme pattern was similar irrespective of degree of retinopathy or nephropathy. The results indicate that concentrations of urinary NAG are positively correlated to the degree of nephropathy, whereas there is no such correlation to the degree of retinopathy.

Acidosis-induced ischemic brain damage: are free radicals involved?

Substantial evidence exists that reactive oxygen species participate in the pathogenesis of brain damage following both sustained and transient cerebral ischemia, adversely affecting the vascular endothelium and contributing to the formation of edema. One likely triggering event for free radical damage is delocalization of protein-bound iron. The binding capacity for some iron-binding proteins is highly pH sensitive and, consequently, the release of iron is enhanced by acidosis. In this study, we explored whether enhanced acidosis during ischemia triggers the production of reactive oxygen species. To that end, enhanced acidosis was produced by inducing ischemia in hyperglycemic rats, with normoglycemic ones serving as controls. Production of H2O2, estimated from the decrease in catalase activity after 3-amino-1,2,4-triazole (AT) administration, was measured in the cerebral cortex, caudoputamen, hippocampus, and substantia nigra (SN) after 15 min of ischemia followed by 5, 15, and 45 min of recovery, respectively (in substantia nigra after 45 min of recovery only). Free iron in cerebrospinal fluid (CSF) was measured after ischemia and 45 min of recovery. Levels of total glutathione (GSH + GSSH) in cortex and hippocampus, and levels of alpha-tocopherol in cortex, were also measured after 15 min of ischemia followed by 5, 15, and 45 min of recovery. The results confirm previous findings that brief ischemia in normoglycemic animals does not measurably increase H2O2 production in AT-injected animals. Ischemia under hyperglycemic conditions likewise failed to induce increased H2O2 production. No difference in free iron in CSF was observed between animals subjected to ischemia under hyper- and normoglycemic conditions. The moderate decrease in total glutathione or alpha-tocopherol levels did not differ between normo- and hyperglycemic animals in any brain region or at any recovery time. Thus, the results failed to give positive evidence for free radical damage following brief periods of ischemia complicated by excessive acidosis. However, it is possible that free radical production is localized to a small subcellular compartment within the tissue, thereby escaping detection. Also, the results do not exclude the possibility that free radicals are pathogenetically important after ischemia of longer duration.

Increased levels of plasma homocysteine are associated with nephropathy, but not severe retinopathy in type 1 diabetes mellitus

The reactive vascular-injuring amino acid homocysteine was measured in plasma samples from 79 well-characterized type 1 diabetic patients and 46 control subjects. Patients with proliferative retinopathy had higher homocysteine levels (15.0 +/- 6.3 mumols l-1; mean +/- SD, p less than 0.001; n = 42) than those with progressive retinopathy during a two-year period (10.4 +/- 1.6 mumols l-1; n = 12), no or minimal retinopathy (10.7 +/- 4.3 mumols l-1; n = 25), and the control subjects (11.0 +/- 3.4 mumols l-1). Within the group of patients with proliferative retinopathy increased homocysteine levels were confined to those patients that had serum creatinine levels greater than 115 mumols l-1 and/or an albumin:creatinine clearance ratio greater than or equal to 0.02 x 10(-3) (17.0 +/- 5.9 mumols l-1; n = 23), whereas those with no or only minimal nephropathy had levels (12.1 +/- 5.5 mumols l-1; n = 18) that were not different from the control group. We conclude that neither type 1 diabetes mellitus nor diabetic retinopathy per se is associated with increased plasma homocysteine levels. In contrast, homocysteine accumulates, probably owing to reduced glomerular filtration, in diabetic patients with advanced nephropathy. This suggests that homocysteine might contribute to the accelerated development of macroangiopathy seen especially in this subgroup of diabetic patients.

The association between plasma beta-hexosaminidase and its isoenzyme patterns and retinopathy in type 1 diabetes mellitus

beta-Hexosaminidase and its isoenzyme patterns were investigated in plasma from patients with Type 1 diabetes mellitus. The patients were divided into three main groups matched for duration of diabetes: (a) proliferative retinopathy (b), progress of retinopathy within a two-year period (c) and with no background retinopathy. When all patients were compared to a reference group, a significant increase of plasma beta-hexosaminidase activity was found. Patients with proliferative retinopathy had significantly increased activity of plasma beta-hexosaminidase compared to the reference group but not compared to the other diabetic patients. The isoenzyme distribution was not different in any of the diabetic subgroups compared to the reference group. It was also shown that various degrees of diabetic nephropathy did not influence total plasma Hex or the isoenzyme pattern.

A study of exercise-induced microalbuminuria in type I (insulin-dependent) diabetes mellitus

Microalbuminuria is thought to be an important prognostic factor in diabetes mellitus. To study the influence of changes in blood pressure on the development of microalbuminuria during exercise, two exercise tests were carried out. A total of 32 insulin dependent diabetic men whose age at onset was less than 30 years, mean duration of diabetes 14 years (range 7 to 21) and mean age 29 years (range 21 to 40), and who did not have albuminuria (N-labstix negative) were studied. The diabetic patients were compared with a total of 29 age-matched male control subjects. Urinary albumin excretion was measured during two exercise tests: at a standardised workload (150 W) for 30 min, and at a standardised heart rate for 25 min. The diabetic patients had higher albumin excretion rates during both exercise tests compared with the control subjects. Blood pressure and heart rate during exercise were significantly higher in diabetic patients compared with control subjects in the standardised workload test. If the test was individualised to achieve the same standardised heart rate there was no significant difference in blood pressure between the diabetic patients and the control subjects. These results indicate that the diabetic kidneys were more sensitive than the healthy kidneys to similar degrees of haemodynamic stress induced by exercise.

Hydrogen peroxide production in ischaemic retina: influence of hyperglycaemia and postischaemic oxygen tension

Free radicals have recently been proposed to play a role in the development of diabetic retinopathy. Ischaemia and hyperglycaemia followed by recirculation have been suggested to initiate free radical production in other tissues and the aim of the present study was to examine whether this could also be the case in the retina. The present study showed retinal cell damage, as measured by pycnotic cells, to be more pronounced when ischaemia was combined with hyperglycaemia than when combined with normoglycaemia. As an indication of free radical production, catalase activity was measured, reflecting the production of hydrogen peroxide (H2O2). Small amounts of H2O2 were found to be generated in the normal retina, but did not increase during ischaemia and hyperglycaemia followed by recirculation. It thus seems, as if hyperglycaemia aggravates the harmful effects of ischaemia, but with the methods used, there does not seem to be any increase in free radical production (as measured by H2O2 production) in normal rat retina during ischaemic and hyperglycaemic conditions.

Free radical production and ischemic brain damage: influence of postischemic oxygen tension

It is now becoming increasingly clear that free radicals contribute to brain damage in several conditions, such as hyperoxia and trauma. It has been more difficult to prove that free radical production mediates ischemic brain damage, but it has often been suggested that it may be a major contributor to reperfusion damage, observed following transient ischemia. Recent results demonstrate that cerebral ischemia of long duration, particularly when followed by reperfusion, leads to enhanced production of partially reduced oxygen species, notably hydrogen peroxide (H2O2). It has also been suggested that postischemic hyperoxia, e.g. an increased oxygen tension during the recirculation period, adversely affects recovery following transient ischemia. Other data support the notion that brain damage caused by permanent ischemia (stroke) is significantly influenced by production of free radicals. The present study, however, fails to show that recirculation following brief periods of ischemia (15 min) leads to an enhanced H2O2 production, and that hyperoxia aggravates the ischemic damage. This study was undertaken to reveal whether variations in oxygen supply in the postischemic period following forebrain ischemia in rats affect free radical production and the brain damage incurred. To that end, rats ventilated on N2O/O2 (70:30) were subjected to 15 min of transient ischemia. Normoxic animals were ventilated with the N2O/O2 mixture, hyperoxic animals with 100% O2, and hypoxic ones with about 10% O2 (balance either N2O/N2 or N2) during the recirculation. At the end of this period, the animals were decapitated for assessment of H2O2 production with the aminotriazole/catalase method. This method is based on the notion that aminotriazole interacts with H2O2 to inactivate catalase; thus, the rate of inactivation of catalase in aminotriazole treated animals reflects H2O2 production. In a parallel series, animals ventilated with one of the three gas mixtures in the early recirculation period, respectively, were allowed to recover for 7 days, with subsequent perfusion-fixation of brain tissues and light microscopical evaluation of the brain damage. Animals given aminotriazole, whether rendered ischemic or not, showed a reduced tissue catalase activity, reflecting H2O2 production in the brain. Hyperoxic animals failed to show increased tissue H2O2 production, while hypoxic ones showed a tendency towards decreased production. However, all three groups (hypo, normo- and hyperoxic) had similar density and distribution of neuronal damage. These results suggest that although postischemic oxygen tensions may determine the rates of H2O2 production, variations in oxygen tensions do not influence the final brain damage incurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Albuminuria and associated medical risk factors: a cross-sectional study in 451 type II (noninsulin-dependent) diabetic patients. Part 2

The association between urinary albumin concentration (UAC) in a morning urine sample and medical risk factors was evaluated in a cross-sectional study of 451 type II (noninsulin-dependent) diabetic patients. The following four groups of patients were created according to their urinary albumin levels: A) normal (less than 12.5 mg/L); B) high normal (12.5-30 mg/L); C) microalbuminuria, ie, incipient nephropathy (31-299 mg/L); and D) clinical nephropathy (greater than or equal to 300 mg/L). The patients with high normal levels had higher HbA1c and systolic blood pressure levels than patients with values within normal limits. The prevalence of incipient and clinical diabetic nephropathy was 20 and 7%, respectively. Incipient nephropathy was associated with higher blood pressures and body weights. Patients with clinical nephropathy had even further increases in these parameters, were older, and had longer duration of diabetes. In both groups of nephropathy, men were preponderant. Thirty six percent of all patients and 73% of patients with clinical nephropathy were treated for hypertension; 55% were treated with insulin. The insulin-treated patients had poorer metabolic control, but there were no differences in blood pressure or serum creatinine levels as compared with those of patients not receiving insulin treatment. The proportion of patients with severe retinopathy increased with the degree of albuminuria, although 22% of the patients with clinical nephropathy continued to be nonretinopathic.

Urine and serum levels of the carboxyterminal domain (NCl) of collagen IV in membranous glomerulonephritis and diabetic nephropathy

Serum and urinary concentrations of NCl, the non collagenous globular domain of collagen IV, were used as markers for turnover of basement membranes. NCl levels were studied in membranous glomerulonephritis and diabetic nephropathy. Thirteen patients with membranous glomerulonephritis and 8 insulin-dependent diabetic patients with diabetic nephropathy were compared to 16 apparently healthy control subjects. The patients with membranous glomerulonephritis had lower levels of NCl in serum and urine compared to the control subjects. In comparison, the patients with diabetic nephropathy had similar levels of NCl in serum and urine as the control subjects. Furthermore, among patients with membranous glomerulonephritis, those with hypertension had higher serum levels of NCl than those without, which may indicate that hemodynamic factors influence the basement membrane collagen metabolism. It is suggested that there are differences in basement membrane turnover in membranous glomerulonephritis and diabetic nephropathy although there are similarities in glomerular histopathological features. Other possible mechanism are discussed. Further studies are needed to confirm the suggested mechanism.

Albuminuria and associated medical risk factors: a cross-sectional study in 476 type I (insulin-dependent) diabetic patients. Part 1

Albumin concentration in a morning urine sample was analyzed in a cross-sectional study in 476 insulin-dependent diabetic patients. The following groups of patients were defined: A) normal urinary albumin (urine albumin less than 12.5 mg/L); B) high normal albuminuria (12.5-30 mg/L); C) microalbuminuria, ie, incipient nephropathy (31-299 mg/L); and D) clinical nephropathy (greater than or equal to 300 mg/L). The prevalences of incipient and clinical diabetic nephropathy were 24.8 and 14.4%, respectively. There were no differences in clinical parameters such as age, age at onset or duration of diabetes, blood pressure, serum creatinine, or HbA1c levels between groups A and B. The frequency of retinopathy in these groups was 55 and 50%, respectively. In group C, there were increases in age, duration of diabetes, blood pressure, serum creatinine, and HbA1c levels. The frequency of retinopathy was higher (80%), and more patients had severe forms (47%). In group D, there were further increases in all parameters and, in addition, younger age at onset of diabetes. The frequency of retinopathy was 97%, and severe forms of retinopathy were more common (86%). Seventeen percent of the patients were treated for hypertension. These patients were older, had longer duration of diabetes, and had higher levels of blood pressure, serum creatinine, and urinary albumin, as well as a younger age at onset of diabetes than patients not requiring antihypertensive treatment.

Urinary excretion of the carboxy terminal domain of type IV collagen is associated with kidney size and function in IDDM

We evaluated whether urinary excretion of the carboxy terminal domain (NC1) of Type IV collagen is associated with glomerular filtration rate and kidney size in Type I (insulin-dependent) diabetes mellitus (IDDM). Urinary excretion rate of NC1, glomerular filtration rate (GFR), and kidney size were measured in 16 men with Type I diabetes. Their mean age was 33.3 +/- 6.1 years with a duration of diabetes of 14.9 +/- 3.7 years (mean +/- SD). The urinary excretion rate of NC1 was higher in the diabetic patients than in 18 healthy control subjects. Urinary excretion of NC1 was associated with both kidney size, parenchymal width, and GFR (r = 0.73, p = 0.001; r = 0.63, p = 0.009; r = 0.53, p = 0.04, respectively). The exact relationship between these factors and basement membrane turnover/synthesis remains to be elucidated.