The bulk of glucose that is filtered by the renal glomerulus is reabsorbed by the glucose transporters of the proximal convoluted tubular epithelium. However, it has been difficult to investigate this in diseases such as type 2 diabetes because of the inability to isolate primary renal cells from patients without a renal biopsy. We report here a method for the immunomagnetic isolation and novel primary culture of human exfoliated proximal tubular epithelial cells (HEPTECs) from fresh urine. The primary isolates are highly enriched and differentiated and express characteristic proximal tubular phenotypic markers. They continue to express the proximal tubular markers CD13/aminopeptidase-N, sodium glucose cotransporter (SGLT) 2, and alkaline phosphatase through up to six subsequent subcultures in a similar way to human proximal cells isolated from renal biopsies. In a hyperglycemic environment, HEPTECs isolated from patients with type 2 diabetes expressed significantly more SGLT2 and the facilitative glucose transporter GLUT2 than cells from healthy individuals. We also demonstrated a markedly increased renal glucose uptake in HEPTECs isolated from patients with type 2 diabetes compared with healthy control subjects. Our findings indicate for the first time in a human cellular model that increased renal glucose transporter expression and activity is associated with type 2 diabetes. Diabetes 54:3427-3434, 2005

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the promotion of exercise through brisk-walking advice given by nursing staff may have a small, but clinically important, impact on bone mineral density but is associated with an increased risk of falls. Self-paced brisk walking is difficult to evaluate in randomized controlled trials because of drop-outs, placebo group exercise, limited compliance and lack of standardization of the duration and intensity of walking. Further work is needed to evaluate the best means of safely achieving increased activity levels in different groups, such as older women and those at high risk of fractures.

Abstract. We have examined transport, sites of photosensitization, and plasma protein binding by sulfonated derivatives of tetraphenylporphine in vitro and tumor localization of these products in vivo. Studies carried out in culture indicate that the mono‐sulfonated porphyrin sensitized mainly at intracellular loci while drugs with 2 or 3 sulfonates caused photodamage at membrane sites. But the number and distribution of sulfonates were majors factor in both accumulation and efficiency of photodamage. The product with 2 adjacent sulfonates was the most potent photosensitizer; the presence of more or fewer sulfonate residues led to reduced uptake and sensitization. Steady‐state accumulation of drugs with one, two (opposite), three or four sulfonates was rapid, while uptake of the disulfonated (on adjacent rings) porphine was slower. Products bearing one to four sulfonates localized equally well in vivo, but sites of localization varied considerably. Drugs with one sulfonate, or two sulfonates on adjacent rings partitioned into neoplastic cells, analogs with two (opposite), three or four sulfonates partitioned to tumor stroma. Plasma binding studies show that drugs with one or two (adjacent) sulfonates bound to VLDL, LDL and HDL components of plasma, while the tri and tetra‐sulfonated analogs bound progressively more to albumin. These results suggest that tumor localization can occur via two pathways: one mediated by lipoprotein binding and leading to dye accumulation in neoplastic cells, another associated with albumin binding and leading to dye accumulation in stromal elements of neoplastic tissues.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-dependent transcription factor that belongs to the nuclear receptor family that plays a critical role in adipocyte differentiation and lipid metabolism. Here we report for the first time that PPARgamma is expressed in human renal cortical collecting ducts (CCD), segments of the nephor involved in regulation of sodium and water homeostasis via action of the epithelial sodium channel (ENaC). ENaC activity is regulated by the hormones aldosterone and insulin, primarily through co-ordinate actions on serum and glucocorticoid regulated kinase 1 (SGK1). We show that SGK1 activity is stimulated by treatment of a human CCD cell line with PPARgamma agonists, paralleled by an increase in SGK1 mRNA that is abolished by pretreatment with a specific PPARgamma antagonist, and that this leads to increased levels of cell surface ENaCalpha. Electrophoretic mobility shift assays suggest that these effects are caused by binding of PPARgamma to a specific response element in the SGK1 promoter. Our results identify SGK1 as a target for PPARgamma and suggest a novel role for PPARgamma in regulation of sodium re-absorption in the CCD via stimulation of ENaC activity. This pathway may play a role in sodium retention caused by activation of PPARgamma in man.

No abstract

The distinctive cortical uptake of the tracer 18F‐FDDNP (2‐(1‐{6‐[(2‐fluoroethyl(methyl)amino]‐2‐naphthyl}ethylidene)malononitrile) in Alzheimer’s disease (AD) is believed to be because of its binding to both neurofibrillary tangles (NFTs) and highly fibrillar senile plaques. We therefore investigated the binding of a tracer concentration of 3H‐FDDNP to brain sections containing AD hallmark pathologies. Semi‐adjacent sections were labelled with 3H‐PIB (Pittsburgh compound‐B, 2‐[4′‐(methylamino)phenyl]‐6‐hydroxybenzothiazole) and 14C‐SB13 (4‐N‐methylamino‐4′‐hydroxystilbene) for comparison. Neocortical sections containing widespread senile plaques and cerebrovascular amyloid angiopathy, produced a sparse and weak labelling following incubation with 3H‐FDDNP. Furthermore, in sections containing NFTs, there was no overt labelling of the pathology by 3H‐FDDNP. In contrast, sections labelled with 3H‐PIB displayed extensive labelling of diffuse plaques, classical plaques, cerebrovascular amyloid angiopathy and NFTs. 14C‐SB13 produced a broadly similar binding pattern to PIB. Radioligand binding assays employing in vitro generated amyloid‐β peptide fibrils demonstrated a ∼10‐fold reduced affinity for 3H‐FDDNP (85.0 ± 2.0 nM) compared with 3H‐PIB (8.5 ± 1.3 nM). These data provide an alternative mechanistic explanation for the observed low cortical uptake of 18F‐FDDNP in AD; in that the ligand is only weakly retained by the hallmark neuropathology because of its low affinity for amyloid structures.

Although it is known that collagen imparts mechanical strength to bone no detailed biochemical analysis has been made of osteoporotic bone collagen. We report for the first time significant changes in the properties of the collagen. Analysis of collagen types revealed little change in the proportion of Type III collagen, but in some cases there was a significant loss of the Type VI. However, the major differences were observed in the post-translational modifications, namely, in the stabilizing cross-links and the hydroxylation of the collagen. These changes indicated a higher turnover in the head region compared to the neck region of the femoral head and are consistent with the susceptibility of the neck region to fracture. Clearly, the collagen is altered in osteoporosis and these changes may play a role in the pathogenesis of the disease.