The potential for early diagnosis of pulmonary arterial hypertension using lung iodine-123-metaiodobenzylguanidine (123I-MIBG) uptake: A case report.

Previous reports have found evidence that the lung uptake of iodine-123-metaiodobenzylguanidine (123I-MIBG) represents pulmonary vascular endothelial function. Therefore, it was believed that the reduced lung uptake of 123I-MIBG in patients with pulmonary artery hypertension may indicate poor pulmonary vascular endothelial function in those patients. In our previous report, we analyzed the lung uptake of 123I-MIBG in patients with pulmonary hypertension, and demonstrated that it is lower in patients with pulmonary arterial hypertension (PAH) than in those with chronic thromboembolic pulmonary hypertension and controls, suggesting that reduced uptake of 123I-MIBG in patients with PAH indicates endothelial dysfunction of the pulmonary artery. In the current report, we describe a 46-year-old woman diagnosed with scleroderma whose lung uptake of 123I-MIBG was decreased on admission, but she was not diagnosed with pulmonary artery hypertension at that time because her pulmonary artery pressure during right heart catheterization was not elevated. However, she was diagnosed with borderline PAH 2 years later. The lung uptake of 123I-MIBG was reduced before a reduction in %DLCO was observed. This report suggests that the lung uptake of 123I-MIBG may be useful for the early diagnosis of pulmonary artery hypertension.

Biocompatibility study of different hyaluronan products for intra-articular treatment of knee osteoarthritis.

BACKGROUND: Intra-articular (IA) injection of hyaluronic acid (HA) (IA-HA) is a well-recognized treatment option for pain associated with symptomatic knee osteoarthritis (OA). IA-HA products differ in their HA content, molecular weight, cross-linking, and source of HA. These differences are assumed to affect the biocompatibility of the IA-HA products once injected inside the knee joint. METHODS: In the present study, we investigated the biocompatibility of three multiple-injection IA-HA products available in the global market. These included SUPARTZ FX™, a medium range molecular weight HA derived from rooster comb (Avian-HA); ORTHOVISC®, a high range molecular weight HA obtained through biological fermentation (Bio-HA); and SYNVISC®, a high molecular weight cross-linked hyaluronan derived from rooster comb (Avian-CL-HA). Rabbit knee joint tissues were histologically and biochemically examined after IA injection of the products. Furthermore, we compared the amounts of impurities in the IA-HA products. RESULTS: IA injection of Avian-CL-HA into rabbit knee joints induced the aggregation of inflammatory cells, infiltration of eosinophils, and an increase in the number of cells in the synovial fluid. However, these effects were not seen in the Avian-HA and Bio-HA groups. The residual protein content and the contaminant levels of bacterial endotoxins were below the limit of quantitation in all HA products. Avian-CL-HA contained relatively a large amount of (1 → 3)-ß-D-glucan, but this was below the lower limit of quantification in the other HA products. CONCLUSIONS: The present results clearly demonstrate that the biocompatibility of Avian-HA is comparable to that of Bio-HA, and they were both considered to have a favorable safety profile for the treatment of symptomatic OA of the knee. However, immunostimulatory activity was observed after injection of Avian-CL-HA: this might be a result of its unique cross-linking structure and/or the considerable amount of (1 → 3)-ß-D-glucan impurity present in the formulation.

Keratan sulfate restricts neural plasticity after spinal cord injury.

Chondroitin sulfate (CS) proteoglycans are strong inhibitors of structural rearrangement after injuries of the adult CNS. In addition to CS chains, keratan sulfate (KS) chains are also covalently attached to some proteoglycans. CS and KS sometimes share the same core protein, but exist as independent sugar chains. However, the biological significance of KS remains elusive. Here, we addressed the question of whether KS is involved in plasticity after spinal cord injury. Keratanase II (K-II) specifically degraded KS, i.e., not CS, in vivo. This enzyme digestion promoted the recovery of motor and sensory function after spinal cord injury in rats. Consistent with this, axonal regeneration/sprouting was enhanced in K-II-treated rats. K-II and the CS-degrading enzyme chondroitinase ABC exerted comparable effects in vivo and in vitro. However, these two enzymes worked neither additively nor synergistically. These data and further in vitro studies involving artificial proteoglycans (KS/CS-albumin) and heat-denatured or reduced/alkylated proteoglycans suggested that all three components of the proteoglycan moiety, i.e., the core protein, CS chains, and KS chains, were required for the inhibitory activity of proteoglycans. We conclude that KS is essential for, and has an impact comparable to that of CS on, postinjury plasticity. Our study also established that KS and CS are independent requirements for the proteoglycan-mediated inhibition of axonal regeneration/sprouting.

Hyaluronan oligosaccharides promote functional recovery after spinal cord injury in rats.

Hyaluronan is a component of the extracellular matrix of the central nervous system, and forms perineuronal nets around neurons. It has been recently reported that the hyaluronan-degrading enzyme hyaluronidase promotes lateral mobility of AMPA-type glutamate receptors and enhances synaptic plasticity. However, the biological significance of hyaluronan-degrading products (oligosaccharides) has not been studied in depth. Here we investigated the effects of hyaluronan oligosaccharides on motor function recovery after spinal cord injury in rats. The disaccharide HA2 and especially the tetrasaccharide HA4, significantly improved motor function, unlike the case with oligosaccharides composed of 6-12 saccharides. Consistent with this finding, HA4 treatment enhanced axonal regeneration/sprouting, as assessed by corticospinal tract tracer fiber counts. HA4 treatment also significantly suppressed accumulation of Iba-1-positive cells in a lesion two weeks after injury. In vitro experiments demonstrated that NMDA-induced neuronal cell death was partly blocked by HA4, but not by other oligosaccharides, whereas proteoglycan-mediated inhibition of neurite outgrowth was not affected by treatment with any oligosaccharide examined. Taken together, the present results revealed that due in part to its neuroprotective activity, HA4 promotes motor function recovery after spinal cord injury.

Highly conserved cysteines of mouse core 2 beta1,6-N-acetylglucosaminyltransferase I form a network of disulfide bonds and include a thiol that affects enzyme activity.

Core 2 beta1,6-N-acetylglucosaminyltransferase I (C2GnT-I) plays a pivotal role in the biosynthesis of mucin-type O-glycans that serve as ligands in cell adhesion. To elucidate the three-dimensional structure of the enzyme for use in computer-aided design of therapeutically relevant enzyme inhibitors, we investigated the participation of cysteine residues in disulfide linkages in a purified murine recombinant enzyme. The pattern of free and disulfide-bonded Cys residues was determined by liquid chromatography/electrospray ionization tandem mass spectrometry in the absence and presence of dithiothreitol. Of nine highly conserved Cys residues, under both conditions, one (Cys217) is a free thiol, and eight are engaged in disulfide bonds, with pairs formed between Cys59-Cys413, Cys100-Cys172, Cys151-Cys199, and Cys372-Cys381. The only non-conserved residue within the beta1,6-N-acetylglucosaminyltransferase family, Cys235, is also a free thiol in the presence of dithiothreitol; however, in the absence of reductant, Cys235 forms an intermolecular disulfide linkage. Biochemical studies performed with thiolreactive agents demonstrated that at least one free cysteine affects enzyme activity and is proximal to the UDP-GlcNAc binding site. A Cys217 --> Ser mutant enzyme was insensitive to thiol reactants and displayed kinetic properties virtually identical to those of the wild-type enzyme, thereby showing that Cys217, although not required for activity per se, represents the only thiol that causes enzyme inactivation when modified. Based on the pattern of free and disulfide-linked Cys residues, and a method of fold recognition/threading and homology modeling, we have computed a three-dimensional model for this enzyme that was refined using the T4 bacteriophage beta-glucosyltransferase fold.