Erythrocyte spermidine levels in IDDM patients

OBJECTIVES

To evaluate whether erythrocyte levels of polyamines spermidine and spermine (expressed in nmol/ml packed erythrocytes [PRBCs]) are modified in insulin-dependent diabetes mellitus (IDDM) and are associated with the presence of retinopathy or nephropathy.

RESEARCH DESIGN AND METHODS

We studied erythrocyte spermidine and spermine levels in 38 IDDM patients with or without persistent microalbuminuria (urinary albumin excretion rate [AER] between 20 and 200 micrograms/min), macroalbuminuria (AER greater than 200 micrograms/min), or retinopathy compared with 60 sex- and age-matched control subjects.

RESULTS

Mean +/- SD erythrocyte spermine content was similar in both diabetic (9.7 +/- 5.5 nmol/ml PRBCs) and control (8.8 +/- 3.5 nmol/ml PRBCs) subjects, whereas spermidine was higher in diabetic (19.1 +/- 7.2 nmol/ml PRBCs) than in control (14.5 +/- 4 nmol/ml PRBCs, P = 0.0007) subjects. Moreover, spermidine was significantly higher in the groups with microalbuminuria (n = 11, 22.5 +/- 9.2 nmol/ml PRBCs) and macroalbuminuria (n = 4, 22.2 +/- 5.7 nmol/ml PRBCs) than in both normoalbuminuric (n = 23, 16.9 +/- 5.6 nmol/ml PRBCs) and control (F = 9.78, P = 0.0001) subjects, and correlated with log AER (r = 0.41, P = 0.009). Similarly, proliferative retinopathy was associated with a significant increase in spermidine (n = 5, 20 +/- 7 nmol/ml PRBCs compared with control subjects [P = 0.0009]).

CONCLUSIONS

Our data suggest that erythrocyte spermidine content is increased in IDDM patients associated with both diabetic nephropathy and advanced retinopathy.

Serum spermidine oxidase activity in patients with insulin-dependent diabetes mellitus and microvascular complications

Metabolism of polyamines (spermidine and spermine) is known to be strictly related to the growth processes of eukaryotic cells. Since cell replication processes appear altered in insulin-dependent diabetes mellitus (IDDM), especially when associated with its microvascular complications, the aim of this study was measuring serum spermidine oxidase activity (SOA), a key enzyme in the metabolic pathway of polyamines, in 47 patients with IDDM as compared with 63 healthy control subjects matched for age and sex. Mean SOA levels +/- SD were significantly lower in IDDM patients (177.4 +/- 57.2 mu kat/l) than in controls (247.6 +/- 68.1 mu kat/l; p less than 0.001), being SOA inversely related with daily insulin dose. SOA was moreover significantly higher (but similar to controls) in the group with increased urinary albumin excretion rate (AER persistently greater than 20 micrograms/min); (n = 17; 213.1 +/- 62.6 mu kat/l) in comparison with normoalbuminuric subjects (n = 30; 156.6 +/- 43.5 mu kat/l; F = 21.78; p = 0.0001). SOA was correlated with AER (r = 0.45; p = 0.001), independently of age, duration of disease, serum creatinine, body weight, blood pressure and metabolic control, as shown by a multiple regression analysis model (p = 0.003). Presence of background retinopathy was not associated with modified levels of SOA, which was conversely higher, although not significantly, in the patients with proliferative retinal lesions. In conclusion serum SOA is deeply altered in IDDM patients, being markedly reduced in the whole group of patients and conversely independently increased up to the mean values of controls in presence of increased AER or advanced retinopathy.

Simultaneous liquid-chromatographic determination of urinary vanillylmandelic acid, homovanillic acid, and 5-hydroxyindoleacetic acid

We describe a liquid-chromatographic method for quantifying, simultaneously by a single procedure, vanillylmandelic acid (VMA), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in urine. After solvent extraction of acidified urine, the analytes were chromatographed on a C8 column, with use of a mobile phase of phosphate buffer (20 mmol/L, pH 4.0) and methanol with a variable gradient elution, and detected fluorometrically. We report the analytical recovery, sensitivity, precision, working linear range, and potential for interference from similar molecules or drugs. The results of such tests demonstrate that the proposed method is sensitive and reproducible. It is, furthermore, easy to perform, and thus is suitable for use in the clinical laboratory.

Simultaneous liquid-chromatographic determination of urinary vanillylmandelic acid, homovanillic acid, and 5-hydroxyindoleacetic acid

We describe a liquid-chromatographic method for quantifying, simultaneously by a single procedure, vanillylmandelic acid (VMA), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in urine. After solvent extraction of acidified urine, the analytes were chromatographed on a C8 column, with use of a mobile phase of phosphate buffer (20 mmol/L, pH 4.0) and methanol with a variable gradient elution, and detected fluorometrically. We report the analytical recovery, sensitivity, precision, working linear range, and potential for interference from similar molecules or drugs. The results of such tests demonstrate that the proposed method is sensitive and reproducible. It is, furthermore, easy to perform, and thus is suitable for use in the clinical laboratory.

[An interesting case of monoclonal component]

The authors present an interesting case of monoclonal component concerning a 61 years old patient, incorrectly identifiable with the IFE technique only. Moreover they describe the analytic methodology used to identify the monoclonal component which resulted to be secreted in three different ways of polymerization.

[Serologic study of toxoplasmosis in an ambulatory population in 1984-1986]

The authors refer the results of a serological investigation about Toxoplasmosis done on 4119 patients during 1984-1986 related to a similar research executed on 2119 patients during 1976-1979. The results show a constant yearly increase of requests of Toxoplasmosis test and a progressive increase of the serologically negative cases. The authors suggest an improvement of Toxoplasmosis epidemiology.

Raised plasma fibronectin concentration is related to the presence of diabetic retinopathy

Plasma concentrations of fibronectin were studied in 152 diabetics (77 males, 75 females), divided according to their hypoglycemic treatment, and in 60 normal subjects (30 males, 30 females) closely matched for age. In both sexes no significant difference of plasma fibronectin (PF) levels was observed between controls and treated groups. In the whole group of diabetics PF levels were weakly correlated with age (r = 0.16; p less than 0.05) and not associated with HbA1 or duration of illness. Both male and female diabetics, either on sulfonylureas or insulin, with retinopathy (background, except for 2 proliferative in the group of insulin-requiring females) were characterized by significantly higher PF concentrations than either controls or patients without retinopathy.

[A and B apoproteins and serum lipids in clinically healthy males]

Serum levels of total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C), LDL cholesterol (LDL-C), Apoprotein A (Apo A) and Apoprotein B (Apo B) were determined in 125 healthy male subjects (bank clerks), aged 20-59 years, in order to screen risk factors of atherosclerosis (ATS) in our population. TC, TG, LDL-C and Apo B increase with aging, while HDL-C and Apo A do not. HDL-C correlates inversely with LDL-C, Apo B ad TG and positively with Apo A. LDL-C, TC and TG show a positive correlation with Apo A. Weight index, cigarette smoking, systolic blood pressure (SBP) negatively affect HDL-C levels which present a positive relation with alcohol intake. Apo B, TC and TG are, moreover, significantly increased by smoking and body weight. A multiple linear regression analysis choosing HDL-C and Apo B as dependent variables indicates that Apo A, TG, SBP, age and alcohol consumption are the attributes mostly associated with HDL-C while TC, smoking, Apo A and SBP are the independent variables which best explain total variance of Apo B. It is worth noting, in this respect, the effect of smoking on Apo B: such a result could provide a further explanation of the well-known connection between smoking and ATS.