RecA protein forms two types of filament structures in the presence or absence of nucleotide cofactors. We recently constructed two molecular models of the DNA structure, the unwound form (N-type ...structure) and the twisted form (S-type structure), which correspond to the helical pitches of the extended form (ATP form) and compressed form (non-nucleotide form) of the RecA filament, respectively. If ATP hydrolysis is unidirectional and cooperative, and if the extended and compressed forms of RecA filament are interconvertible, the coordinated conformational change travels along the filament. While the RecA filament undergoes this worm-like motion, the wave of conformational change between the unwound and the twisted forms of DNA travels as ATP hydrolyzes, which makes the DNA strands rotate.
RecA-double stranded (ds) DNA complexes have been studied by atomic force microscopy (AFM). When the complexes were prepared in the presence of ATP gamma S, fully covered RecA-dsDNA filaments were ...observed by AFM. When the concentration of RecA proteins was lower, various lengths of filaments were found. The variation of the observed structures may directly reflect the real distribution of the intermediate complexes in the reaction mixture, as the mixture was simply deposited on a mica surface for AFM observation without special fixation or staining. The use of a carbon nanotube (CNT) AFM tip enabled high resolution to reveal the periodicity of RecA-dsDNA filaments. Our observations demonstrated the potential of the AFM method for the structural studies of the RecA-dsDNA complexes, especially their intermediate states.
The patient was a 64-year-old woman who showed muscle weakness and tremor of upper extremities and gait disturbance at the age of 62 years. The symptoms progressed and she was admitted to our ...hospital. Neurological examination revealed muscle weakness, muscle atrophy and fasciculation bilaterally in the upper extremities. The deep tendon reflexes were reduced in the upper extremities and increased in the lower extremities, but Babinski's sign was not present. There was mild hand tremor at rest (right greater than left). Muscle rigidity was also evident. Her gait was small-stepped and her trunk was bent forward. She showed hypomimia, but no dementia was detected. She died of respiratory failure 7 months after admission. The duration of the illness was about 2 years. At autopsy, macroscopic examination showed depigmentation of the substantia nigra and locus ceruleus, and atrophy of the anterior roots of the spinal cord. Microscopic examination revealed a few senile plaques in the temporal cortex. In the substantia nigra, the number of melanin-containing cells was decreased in its central parts. A few Lewy bodies were found in some of the remaining neurons, and melanin pigment migrated into the parenchyma. In the locus ceruleus and dorsal motor nucleus of vagus, abundant Lewy bodies and mild astrocytosis were seen. A few Lewy bodies were also seen in the nucleus raphe, nucleus basalis of Meynert and hypothalamic nuclei. Severe neuronal loss of the anterior horn cells was observed in the cervical segment, and to a lesser degree, in the lumbo-sacral segments. segments.(ABSTRACT TRUNCATED AT 250 WORDS)
The retinoblastoma susceptibility gene product (RB) is a transcriptional modulator. One of the targets for this modulator
effect is the AP-1 binding site within the c- jun and collagenase promoters. ...The physical interactions between RB and c-Jun were demonstrated by co-immunoprecipitation of these
two proteins using anti-c-Jun or anti-RB antisera, glutathione S -transferase affinity matrix binding assays in vitro , and electrophoretic mobility shift assays. The C-terminal site of the leucine zipper of c-Jun mediated the interaction with
RB. Although the B-pocket domain of RB alone bound to c-Jun, a second c-Jun binding site in the RB was also suggested. Mammalian
two-hybrid-based assay provided corroborative evidence that transactivation of gene expression by RB required the C-terminal
region of c-Jun. We conclude that RB enhances transcription activity mediated through the AP-1 binding site. Adenovirus E1A
or human papillomavirus E7 inhibits RB-mediated transcription activity. These data reveal that the interactions between these
two distinct classes of oncoproteins RB and c-Jun may be involved in controlling cell growth and differentiation mediated
by transcriptional regulation.
Background: Since 1998, clinical testing has shown that non-pulsatile blood flow is well tolerated by the human organism and these miniaturized blood pumps offer exciting new perspectives. In 2004, ...the DuraHeart (Terumo Heart Inc., Ann Arbor, MI, USA), a third-generation continuous flow pump with magnetic levitation became available for clinical testing. We report our initial experience bridging five patients successfully to cardiac transplantation. Materials and Methods: The DuraHeart is a fully implantable centrifugal blood pump with a magnetically levitated impeller and hydrodynamic bearing. Five male patients (age: 44-15 years, 31-61 years) suffering from end-stage left heart failure underwent successful implantation of the pump for use as a bridge to transplantation. The clinical course was monitored including pump performance and hemodynamic changes. Results: In the initial postoperative period, mean pump flow was 5.8-0.8 Umin., which equals a mean cardiac index of 2.9-0.3 L*min'*m 2. The initial postoperative period was characterized by a non-pulsatile blood flow pattern followed by increasing pulse pressure amplitudes within the first 3 postoperative days. All patients were extubated on POD 1 and early mobilized. Hemolysis parameters remained within physiological range until a donor organ became available 202, 81, 96, 128 and 47 days after VAD implantation (mean plasma free hemoglobin 4 weeks postoperatively: 1.6-0.75 mg/dL, mean LDH: 302-65 U/L). Conclusions: First clinical implants of the Terumo DuraHeart in Vienna have shown promising initial results. Patients could be early mobilized and the VADs demonstrated stable, safe and sufficient circulatory support until successful cardiac transplantation.
RecA filaments form two types of structures having different helical pitches according to the nucleotide condition. We have investigated the effect of nucleotide cofactor exchange upon the RecA-ssDNA ...filaments by observing a fluorescently-labelled single molecule in water solution. The result indicated that the RecAssDNA filamentous complex is an elastic helical molecule whose length is controlled by binding and release of nucleotide cofactors. We propose that this elastic motion couples to the DNA rotation within the filament by synchronizing the helical phases, and promotes exchange of homologous strands of two DNAs.
In human testis, expression of a novel member of the aldo-keto reductase family was identified. Based on its testis-specific expression, we termed this protein human testis aldo-keto reductase ...(htAKR). In addition to four major isoforms, the existence of multiple alternatively spliced products of htAKR was detected using RT-PCR followed by nested PCR. htAKR was a homologue of mouse liver keto-reductase, AKR1E1, with close similarity in their genomic organizations. htAKR4, the longest isoform, was expressed as a non-fused native form. It exhibited a limited activity toward 9,10-phenanthrenequinone, while no activity toward the steroids or prostaglandins was demonstrated. Using the laser capture microdissection technique and RT-PCR, expression of htAKR was detected in testicular germ cells as well as in interstitial cells. The levels of htAKR mRNA in the tissues obtained from seminoma were much lower than those in normal testes. A significant decline in the htAKR expression was observed when NEC8, a cell line originated from a human testicular germ cell tumour, was exposed to phorbol 12-myristate 13-acetate or 5α-dihydrotestosterone. These results indicate that the expression of htAKR, down-regulated in the testicular tumour, is possibly controlled by mitogenic and hormonal signals.
Human testis specific protein, HTSP, was identified initially by the search of the Expressed Sequence Tag database, followed by the screening of human testis cDNA library. Among various organs ...examined, the HTSP transcripts were detected only in the testis, not in other reproductive organs such as vas deferens and prostate. No cross-hybridizing signal was detected in the testis of mouse or rat, indicating that this gene is specifically expressed in the human testis. We isolated four isoforms, HTSP1, 2, 3 and 4. Screening of the high throughput genomic sequence database indicated the localization of the HTSP gene in chromosome 10. Thus, HTSP isoforms were generated by alternative splicing of a single gene. HTSP4, the longest gene product, was composed of 307 amino acids and shared 56% identity to mouse vas deferens protein as well as human aldose reductase in amino acid levels. Bacterially expressed recombinant HTSP protein showed small but significant activity towards 9,10-phenanthrenequinone among the putative substrates so far tested. Accordingly, HTSP is a new member of the aldo-keto reductase superfamily with as yet unidentified function.
PDF
