Does autonomic neuropathy play a role in erythropoietin regulation in non-proteinuric Type 2 diabetic patients?

AIMS: Erythropoietin (EPO)-deficient anaemia has been described in Type 1 diabetic patients with both severe autonomic neuropathy (AN) and proteinuria. This study was aimed at distinguishing between the effects of AN and nephropathy on haemoglobin and EPO levels in Type 2 diabetic patients at an early stage of diabetic nephropathy. METHODS: In 64 Type 2 diabetic patients (age 52 +/- 10 years, duration 10 +/- 9 years) without overt nephropathy and other causes of anaemia or EPO deficit, we assessed cardiovascular tests of AN, 24-h blood pressure (BP) monitoring, urinary albumin excretion rate (UAE), a full blood count, and serum EPO. RESULTS: Although the Type 2 diabetic patients with AN did not show differences in haemoglobin and EPO when compared with patients without AN, the presence of haemoglobin < 13 g/dl was associated with the presence of AN (chi(2)= 3.9, P < 0.05) and of postural hypotension (chi(2)= 7.8, P < 0.05). In a multiple regression analysis including as independent variables gender, body mass index, duration of diabetes, smoking, creatinine, 24-h UAE, 24-h diastolic BP, ferritin, erythrocyte sedimentation rate, and autonomic score, we found that the only variables independently related to haematocrit were autonomic score, ferritin and erythrocyte sedimentation rate. Finally, the physiological inverse relationship between EPO and haemoglobin present in a control group of 42 non-diabetic non-anaemic subjects was completely lost in Type 2 diabetic patients. The slopes of the regression lines between EPO and haemoglobin of the control subjects and the Type 2 diabetic patients were significantly different (t = 14.4, P < 0.0001). CONCLUSIONS: This study documents an early abnormality of EPO regulation in Type 2 diabetes before clinical nephropathy and points to a contributory role of AN in EPO dysregulation.

Epitope-specific antibodies to the beta(1C) integrin cytoplasmic domain variant.

The beta(1C) integrin is an alternatively spliced variant of the beta(1) subunit that contains a unique 48-amino-acid sequence in its cytoplasmic domain. We have shown previously that beta(1C) is a potent inhibitor of cell proliferation and that in vivo its expression is downregulated in prostate and breast carcinoma. In this study, we describe a panel of specific monoclonal antibodies that react with the beta(1C) cytodomain. We show by immunoblot analysis that the newly generated monoclonal antibodies specifically recognize the beta(1C) cytodomain expressed as glutathione S-transferase fusion protein. The specificity of the antibodies to beta(1C) was confirmed in competition studies by immunoblotting using beta(1C)-specific synthetic peptides. These monoclonal antibodies reacted, in enzyme-linked immunosorbent assays, with the beta(1C) 785-808 peptide but failed to bind the beta(1C) 778-794, beta(1C) 805-825, or beta(1A) 765-798 peptides. Thus, the epitope recognized by the antibodies is located within the Q(795)-F(804) beta(1C) cytoplasmic sequence; this region overlaps the previously described Q(795)-Q(802) domain necessary for beta(1C) to inhibit cell proliferation. To our knowledge, these are the first monoclonal antibodies specific for a beta(1) cytoplasmic isoform. The monoclonal antibodies described here will be useful tools for dissecting functional differences, among beta(1) integrin variants, as well as for the study of the role of beta(1C) in prostate and breast epithelial cell proliferation.

Regulation of mRNA and protein levels of beta1 integrin variants in human prostate carcinoma.

Alterations of integrin expression levels in cancer cells correlate with changes in invasiveness, tumor progression, and metastatic potential. The beta1C integrin, an alternatively spliced form of the human beta1 integrin, has been shown to inhibit prostate cell proliferation. Furthermore, beta1C protein levels were found to be abundant in normal prostate glandular epithelium and down-regulated in prostatic adenocarcinoma. To gain further insights into the molecular mechanisms underlying abnormal cancer cell proliferation, we have studied beta1C and beta1 integrin expression at both mRNA and protein levels by Northern and immunoblotting analysis using freshly isolated neoplastic and normal human prostate tissue specimens. Steady-state mRNA levels were evaluated in 38 specimens: 33 prostatic adenocarcinomas exhibiting different Gleason's grade and five normal tissue specimens that did not show any histological manifestation of benign prostatic hypertrophy. Our results demonstrate that beta1C mRNA is expressed in normal prostate and is significantly down-regulated in neoplastic prostate specimens. In addition, using a probe that hybridizes with all beta1 variants, mRNA levels of beta1 are found reduced in neoplastic versus normal prostate tissues. We demonstrate that beta1C mRNA down-regulation does not correlate with either tumor grade or differentiation according to Gleason's grade and TNM system evaluation, and that beta1C mRNA levels are not affected by hormonal therapy. In parallel, beta1C protein levels were analyzed. As expected, beta1C is found to be expressed in normal prostate and dramatically reduced in neoplastic prostate tissues; in contrast, using an antibody to beta1 that recognizes all beta1 variants, the levels of beta1 are comparable in normal and neoplastic prostate, thus indicating a selective down-regulation of the beta1C protein in prostate carcinoma. These results demonstrate for the first time that beta1C and beta1 mRNA expression is down-regulated in prostate carcinoma, whereas only beta1C protein levels are reduced. Our data highlight a selective pressure to reduce the expression levels of beta1C, a very efficient inhibitor of cell proliferation, in prostate malignant transformation.

In search of a biological pattern for human longevity: impact of apo A-IV genetic polymorphisms on lipoproteins and the hyper-Lp(a) in centenarians.

We studied centenarians to investigate the biological basis of human longevity focusing on the apolipoprotein A-IV and lipoprotein(a), potentially involved in the susceptibility to atherogenic mechanisms. We analyzed two restriction polymorphisms, HinfI347 (alleles +, -) and Fnu4HI360 (alleles 1, 2), and a VNTR (alleles 3, 4) at the 3' region of the apo A-IV gene. The allele frequencies, the lipoprotein concentrations and their association in centenarians and adults have been compared. In centenarians, the HinfI genotype distribution is different (P < 0.05) and the (+13) haplotype is prevalent (0.54 vs. 0.39), with a greater association of (+3), indicating the selection of a favourable allele. The lipoprotein modulation by the apo A-IV polymorphisms is suggested by significant associations in adults ((+/+) homozygotes have lower LDL-cholesterol and apo B than heterozygotes; (1/1) homozygotes have higher TG and apo B than heterozygotes), that in centenarians still exists as a trend. Centenarians show peculiar lipoprotein features: lower LDL-cholesterol (mean 103 vs. 115 mg/dl; P < 0.02), and higher lipoprotein(a) (median 17.5 vs. 4.5; P < 0.002). Large part of them (47%), especially the Hinf(+/+) and the (+13) homozygotes, have a lipoprotein(a) > 20 mg/dl, value considered as the threshold for atherogenic risk, surprisingly compatible with healthy longevity.

A new Italian case of lipoprotein lipase deficiency: a Leu365- > Val change resulting in loss of enzyme activity.

We describe a second Italian family with primary Lipoprotein Lipase deficiency. A new mutation in exon 8 causes a Leu365- > Val change resulting in severe mass reduction and loss of enzyme activity. We suggest that this change interferes with the correct folding and stability of the protein and impairs the assembly of the active homodimer. The procedures applied are useful to screen a large sample of population for genetic variants and allow the clear identification of asymptomatic heterozygous subjects at risk from atherosclerosis disease.