Evidence of global chlorophyll d.

Although analyses of chlorophyll d (Chl d)-dominated oxygenic photosystems have been conducted since their discovery 12 years ago, Chl d distribution in the environment and quantitative importance for aquatic photosynthesis remain to be investigated. We analyzed the pigment compositions of surface sediments and detected Chl d and its derivatives from diverse aquatic environments. Our data show that the viable habitat for Chl d-producing phototrophs extends across salinities of 0 to 50 practical salinity units and temperatures of 1 degrees to 40 degrees C, suggesting that Chl d production can be ubiquitously observed in aquatic environments that receive near-infrared light. The relative abundances of Chl d derivatives over that of Chl a derivatives in the studied samples are up to 4%, further suggesting that Chl d-based photosynthesis plays a quantitatively important role in the aquatic photosynthesis.

Absence of an association between the polymorphisms in the genes encoding adiponectin receptors and type 2 diabetes.

AIMS/HYPOTHESIS: Secreted by adipocytes, adiponectin is a hormone that acts as an antidiabetic and anti-atherogenic adipokine. We recently cloned the genes encoding two adiponectin receptors (ADIPOR1 and ADIPOR2). The aim of this study was to examine whether ADIPOR1 and/or ADIPOR2 play a major role in genetic susceptibility to insulin resistance or type 2 diabetes in the Japanese population. METHODS: By direct sequencing and a search of public databases, we identified single nucleotide polymorphisms (SNPs) in ADIPOR1 and ADIPOR2, and investigated whether these SNPs are associated with insulin resistance and type 2 diabetes in the Japanese population. RESULTS: The linkage disequilibrium (LD) in the chromosomal region of ADIPOR1 was almost completely preserved, whereas the LD in ADIPOR2 was less well preserved. None of the SNPs in ADIPOR1 or ADIPOR2 were significantly associated with insulin resistance or type 2 diabetes. No differences in ADIPOR1 or ADIPOR2 haplotype frequencies were observed between type 2 diabetic and non-diabetic subjects. CONCLUSIONS/INTERPRETATION: Genetic variations in ADIPOR1 or ADIPOR2 are unlikely to lead to a common genetic predisposition to insulin resistance or type 2 diabetes in the Japanese population.

Glycemic control reverses increases in urinary excretions of immunoglobulin G and ceruloplasmin in type 2 diabetic patients with normoalbuminuria.

To examine whether urinary excretions of plasma proteins with molecular radii of 45-55 A and different isoelectric points such as IgG (pI = 7.4) and ceruloplasmin (pI = 4.4) increase selectively in normoalbuminuric type 2 diabetic patients, urinary albumin excretion rate (AER), renal clearances of IgG, ceruloplasmin and alpha2-macroglobulin, and creatinine clearance (Ccr) were studied in timed overnight urine samples of 36 diabetic outpatients and 16 control subjects. Furthermore, to examine effect of glycemic control on these urinary protein excretions, the same analysis was performed before and after glycemic control in 17 diabetic inpatients admitted for glycemic control. Renal clearances of IgG and ceruloplasmin were significantly higher in diabetic outpatients than in the control group, whereas AER and renal clearance of alpha2-macroglobulin did not differ. Glycemic control caused significant decreases in renal clearances of IgG and ceruloplasmin, accompanied with tendency for Ccr to decrease (p = 0.055). The present results, together with our previous finding of selectively increased urinary excretions of 45-55 A sized plasma proteins in parallel with enhanced glomerular filtration rate after acute protein loading, led us to conclude that enhanced intraglomerular hydraulic pressure may cause increases in clearances of IgG and ceruloplasmin, and that this change can be reversed by strict glycemic control in normoalbuminuric diabetic patients.

Determination of optimal protein contents for a protein restriction diet in type 2 diabetic patients with microalbuminuria.

To establish the method by which the optimal dietary protein content for type 2 diabetic patients with nephropathy could be determined, dietary protein content was reduced in gradated steps and renal function was evaluated at the completion of each diet. Eight type 2 diabetic patients with microalbuminuria were examined in this study. Renal function, urinary albumin excretion rate (AER) and urinary excretion rates of prostaglandins were evaluated at the completion of each of three consecutive one-week dietary periods where the protein content was 1.2, 0.8 and 0.6 g x kg Body Weight (BW)(-1) x day(-1) on the first, second and third week, respectively. Filtration fraction (FF), AER and urinary excretion rates of prostaglandin E2 and 6-keto-prostaglandin F1alpha significantly decreased in response to reduced dietary protein content from 1.2 to 0.8 g x kg BW(-1) x day(-1). No additional decreases in FF, AER and urinary excretion rates of these two prostaglandins were obtained after the 0.6 g x kg BW(-1) x day(-1) low protein diet period. The method evaluating renal hemodynamics at the completion of several consecutive one-week dietary periods was confirmed to be useful to determine the optimal protein contents in type 2 diabetic patients with nephropathy. The result showed that the optimal protein content in type 2 diabetic patients with microalbuminuria was 0.8 g x kg BW(-1) x day(-1) and protein restriction of less than 0.8 g x kg BW(-1) x day(-1) was not necessary for patients with this stage of diabetic nephropathy. A part of reasons in which FF decreased after reduced protein content in diet may be due to decreased prostaglandins production in the kidneys.

No association of glutathione S-transferase M1 gene polymorphism with diabetic nephropathy in Japanese type 2 diabetic patients.

Oxidative stress possibly contributes to the development of diabetic nephropathy. Therefore, the levels of endogenous antioxidants may be one of determinants of the susceptibility to diabetic nephropathy. Glutathione S-transferases (GSTs) can work as one of endogenous antioxidants to protect cells from oxidative stress. The M1 member of GST mu class (GSTM1) is polymorphic and only expressed in 55-60% of Caucasians because of the homozygous deletion of the gene (null genotype). Recent studies have provided evidence that the GSTM1 null genotype, i.e. lack of the GSTM1 activity, is associated with an increased susceptibility to lung cancer and colorectal cancer. The present study was conducted to determine whether the genetic polymorphism influences the development of diabetic nephropathy. We examined 105 patients with diabetic nephropathy and 69 patients without diabetic nephropathy in Japanese type 2 diabetic patients with proliferative diabetic retinopathy. GSTM1 genotyping was performed by polymerase chain reaction. The two patient groups were well matched with regard to age, body mass index and HbAlc. GSTM1 null genotype was observed in 48.6% of patients with nephropathy versus 55.1% of patients without nephropathy. The frequency of GSTM1 null genotype was not significantly higher in the patient group with nephropathy than in the patient group without nephropathy. This study is the first to investigate the association of GSTM1 gene polymorphism with the development of diabetic nephropathy. The present results suggest that GSTM1 null genotype does not contribute to the development of diabetic nephropathy in Japanese type 2 diabetic patients.

Effects of protein meals on the urinary excretion of various plasma proteins in healthy subjects.

To examine whether hemodynamic changes in response to acute protein loadings with different protein sources cause increases in urinary excretion of plasma proteins in healthy subjects, urinary excretions of various plasma proteins with various molecular radii and isoelectric points, namely albumin (Alb), IgG, IgG4, ceruloplasmin (CRL), and alpha2-macroglobulin (A2), were measured in healthy subjects after ingestion of a beef meal or of a tuna fish meal. Significant increases in urinary excretions of the negatively charged IgG4 and CRL and of the neutrally charged IgG were found in parallel with enhanced creatinine clearances after each protein ingestion. These renal responses returned to basal levels 9 h after the test. This finding suggests that in healthy subjects, the increase in glomerular filtration rate after acute protein loading caused selective enhancement of urinary excretions of plasma proteins with a molecular radius of approximately 55 A (the radius of IgG, IgG4, and CRL), irrespective of the charge barrier of the glomerulus. The increases in these three plasma proteins may be induced by leakage via the shunt pathway in the glomerulus, as proposed earlier (see text). In contrast, increases in urinary excretions of A2 and Alb were not found. The former finding may be explained by the possibility that A2 would not pass through this pathway, since the molecular radius of A2 (88 A) is larger than that of IgG, although the latter finding may be partially explained by preferential renal tubular reabsorption of Alb.

Effects of short-term glycemic control, low protein diet and administration of enalapril on renal hemodynamics and protein permselectivity in type 2 diabetic patients with microalbuminuria.

To determine whether each of glycemic control (GC), low protein diet (LPD) or administration of angiotensin converting enzyme inhibitor (ACEI) has beneficial effects on diabetic nephropathy through the different mechanisms, changes in charge and size selectivity of glomerulus and renal hemodynamics were analyzed in microalbuminuric type 2 diabetic patients after additive combination therapy (first period: GC only, second period: GC-LPD, third period: GC+LPD+ACEI). To detect improvement of the impairments of glomerular charge selectivity and size selectivity, changes in the ratio of the renal clearance of two plasma proteins with similar molecular radii and different isoelectric points (pIs) (ceruloplasmin and IgG: CRL/IgG) and changes in the ratio of the renal clearance of two plasma proteins with similar pIs and different molecular radii (alpha2-macroglobulin and albumin: alpha2/Alb) were examined before and after each therapy. Creatinine clearance decreased significantly in the first and third periods although slight but not significant decrease was detected in the second period. Filtration fraction was significantly decreased only in the third period. Although renal clearances of Alb, IgG and CRL were decreased in periods of all three therapies, that of alpha2-macroglobulin with a large molecular radius was decreased significantly only after the third therapy. Neither CRL/IgG nor alpha2/Alb changed during these three therapies. These findings suggest that each of three short-term therapies consisting of GC, GC+LPD and GC+LPD+ACEI, reduced proteinuria in microalbuminuric type 2 diabetic patients not through the improvement of renal size and charge selectivities, but through improvement of renal hemodynamics.