No abstract

By establishing a unique screening method, we have isolated yeast mutants that die only after differentiating into cells with a mating projection, and some of them are also defective in Ca2+ signaling. The mutants were classified into five complementation groups, one of which we studied extensively. This mutation defines a new gene, designated MIDI, which encodes an N-glycosylated, integral plasma membrane protein with 548 amino acid residues. The mid)-) mutant has low Ca21 uptake activity, loses viability after receiving mating pheromones, and escapes death when incubated with high concentrations of CaCl2. The MID) gene is nonessential for vegetative growth. The efficiency of mating between AL4Ta mid)-) and MATa mid)-) cells is low. These results demonstrate that MID) is required for Ca2+ influx and mating.

Deficiency of ADAMTS13 is found in patients with thrombotic thrombocytopenic purpura (TTP), and the genetic defects in the ADAMTS13 gene or the autoantibody against ADAMTS13 is thought to be responsible for the development of TTP. The clinical correlation and mechanisms of secondary ADAMTS13 deficiency in other disease states were investigated. In addition to TTP, ADAMTS13 levels were severely decreased in patients with sepsis-induced disseminated intravascular coagulation (DIC). The incidence of acute renal failure and serum creatinine levels in patients with ADAMTS13 activity levels lower than 20% (incidence, 41.2%; creatinine, 160 ؎ 150 M [1.81 ؎ 1.70 mg/dL]) (P < .05) were significantly higher than they were in patients with ADAMTS13 activity levels higher than 20% (incidence, 15.4%; creatinine, 84 ؎ 67 M [0.95 ؎ 0.76 mg/dL]) (P < .01). Additionally, unusually large von Willebrand factor multimers were detected in 26 (51.0%) of 51 patients with ADAMTS13 activity levels lower than 20%. Lower molecular weight forms of ADAMTS13 were found in the plasma of patients with sepsis-induced DIC, suggesting that the deficiency of ADAMTS13 was partially caused by its cleavage by proteases in addition to decreased synthesis in the liver. These data suggested that severe secondary ADAMTS13 deficiency can be associated with sepsis-induced DIC and may contribute to the development of renal failure. (Blood. 2006;107: 528-534)

Here we investigated the pathogenesis of deletion mutant mitochondrial (mt)DNA by generating mice with mutant mtDNA carrying a 4696-basepair deletion (DeltamtDNA4696), and by using cytochrome c oxidase (COX) electron micrographs to identify COX activity at the individual mitochondrial level. All mitochondria in tissues with DeltamtDNA4696 showed normal COX activity until DeltamtDNA4696 accumulated predominantly; this prevented mice from expressing disease phenotypes. Moreover, we did not observe coexistence of COX-positive and -negative mitochondria within single cells. These results indicate the occurrence of inter-mitochondrial complementation through exchange of genetic contents between exogenously introduced mitochondria with DeltamtDNA4696 and host mitochondria with normal mtDNA. This complementation shows a mitochondria-specific mechanism for avoiding expression of deletion-mutant mtDNA, and opens the possibility of a gene therapy in which mitochondria possessing full-length DNA are introduced.

Extensive complementation between fused mitochondria is indicated by recombination of 'parental' mitochondrial (mt) DNA (ref. 1,2) of yeast and plant cells. It has been difficult, however, to demonstrate the occurrence of complementation between fused mitochondria in mammalian species through the presence of recombinant mtDNA molecules, because sequence of mtDNA throughout an individual tends to be uniform owing to its strictly maternal inheritance. We isolated two types of respiration-deficient cell lines, with pathogenic mutations in mitochondrial tRNAIle or tRNALeu(UUR) genes from patients with mitochondrial diseases. The coexistence of their mitochondria within hybrids restored their normal morphology and respiratory enzyme activity by 10-14 days after fusion, indicating the presence of an extensive and continuous exchange of genetic contents between the mitochondria. This complementation between fused mitochondria may represent a defence of highly oxidative organelles against mitochondrial dysfunction caused by the accumulation of mtDNA lesions with age.

Sepsis-induced disseminated intravascular coagulation (DIC) is a serious condition because it is closely linked to the development of multiple organ dysfunctions. We compared molecular fibrinolysis markers for 117 patients with sepsis-induced DIC and 1627 patients with nonseptic DIC. Levels of fibrinogen and fibrin degradation products and D-dimer were significantly lower in sepsis-induced DIC cases than in nonseptic DIC cases. In septic DIC cases, plasma plasminogen activator inhibitor 1 (PAI-1) levels were significantly higher than in nonseptic DIC cases. D-dimer levels were negatively correlated with plasma PAI-1 levels in septic DIC cases. Multiple Organ Dysfunction Scores were significantly higher in septic DIC patients with PAI-1 levels >90 ng/mL than in the group with PAI-1 levels <30 ng/mL. The Kaplan-Meier survival functions until 28 days after DIC diagnosis were significantly lower in the group with PAI-1 levels >90 ng/mL than in the other groups. In a multivariate analysis, plasma PAI-1 levels at DIC diagnosis were an independent risk factor for mortality in sepsis-induced DIC (hazard ratio, 1.012; P = .008). These data suggest that plasma PAI-1 plays an important role in sustaining DIC in septic DIC cases and contributes to multiple organ failure and decreased survival in such patients.

Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surface-modifications by appropriate polymers are key techniques to stably express their characteristics. Herein, we applied cyclic poly(ethylene glycol) (c-PEG), having no chemical inhomogeneity, to provide a polymer topology-dependent stabilization for the surface-modification of gold nanoparticles (AuNPs) through physisorption. By simply mixing c-PEG, but not linear counterparts, enables AuNPs to maintain dispersibility through freezing, lyophilization, or heating. Surprisingly, c-PEG endowed AuNPs with even better dispersion stability than thiolated PEG (HS–PEG–OMe). The stronger affinity of c-PEG was confirmed by DLS, ζ-potential, and FT-IR. Furthermore, the c-PEG system exhibited prolonged blood circulation and enhanced tumor accumulation in mice. Our data suggests that c-PEG induces physisorption on AuNPs, supplying sufficient stability toward bio-medical applications, and would be an alternative approach to the gold–sulfur chemisorption.

We report on a global CCD time-series photometric campaign to decode the pulsations of the nucleus of the planetary nebula NGC 1501. The WC4 central star is an extremely hot, hydrogen-deficient, "O VI"-type object, with some spectroscopic characteristics similar to those of the pre-white-dwarf PG 1159−035 stars. NGC 1501 shows pulsational brightness variations of a few percent with numerous individual periods ranging from 19 to 87 minutes. The pulsation amplitudes and periods are highly variable, suggesting a complex pulsation spectrum that requires a long unbroken time series to resolve. To that end, we obtained CCD photometry of the central star over a two-week period in 1991 November, using a network of observatories around the globe. We obtained nearly continuous coverage over an interval of almost one week in the middle of the run. With this data set, we have identified 10 independent pulsation periods, ranging from 5235 s down to 1154 s. The pulsation modes changed amplitude significantly