Multiple activities of a novel substance, dictyopyrone C isolated from Dictyostelium discoideum, in cellular growth and differentiation.

We report that a novel substance named dictyopyrone C (DPC) has remarkable effects on growth and differentiation of Dictyostelium discoideum Ax-2 cells, in a dose-dependent manner. In the presence of 3-15 microM DPC, differentiation of starving Ax-2 (clone MS) cells was greatly enhanced in submerged culture, when vegetative MS cells were harvested at the mid-late-exponential growth phase (>3 x 10(6) cells per ml) and starved. In contrast, DPC above 30 microM markedly impaired the progression of differentiation including cell aggregation, most of starved cells being round after 3-4 h of DPC application and then lysed during further incubation. In the presence of 30 microM DPC however, MS cells that had been harvested at the early exponential growth phase (<5 x 10(5) cells per ml) and starved became neither round nor lysed and exhibited rather enhanced differentiation. Essentially the same results were obtained in cultures of starved cells on nonnutrient agar. With respect to the DPC effect on MS cells growing in axenic medium, cell lysis and growth inhibition by DPC at concentrations higher than 15 microM were realized in the mid-late-exponential-growth-phase cells (>3 x 10(6) cells per ml) but not in the early-exponential-growth-phase cells (<5 x 10(5) cells per ml). Moreover, analysis using synchronized MS cells has demonstrated that the DPC effect changes in a cell-cycle-dependent manner. In contrast to such unique DPC actions, the pyrone ring of DPC had no effects on growth and differentiation within the range of 3-120 microM tested. These findings strongly suggested the importance of the combined structure of the pyrone ring and the linear carbon chain in revelation of the DPC activities.

Monophasic action potentials of the right atrium in patients with paroxysmal atrial fibrillation.

To investigate the mechanism of atrial fibrillation (AF), monophasic action potentials (MAPs) from the atrial myocardium were studied in 7 patients with paroxysmal AF (PAF) and in 7 control individuals. The MAPs were recorded using a contact catheter during sinus rhythm and continuous pacing at the high right atrium (HRA) with pacing cycle lengths of 600, 500 and 400 ms. MAPs were obtained from 6 sites in each participant. The MAPD90 was measured from onset to 90% of MAP repolarization. Average, maximal and minimal MAPD90 (avMAPD90, maxMAPD90 and minMAPD90) were obtained from all participants. The dispersion of MAPD90 (dispMAPD90) was defined as the difference between maxMAPD90 and minMAPD90. The width of each atrial potential (WAP) and the wavelength index (WLI=MAPD90/WAP) were determined. Average, maximal and minimal WLI (avWLI, maxWLI and minWLI) were obtained from all participants. The avMAPD90 and maxMAPD90 did not significantly differ between the 2 groups. The minMAPD90 in the PAF group was significantly smaller than that in the control group at HRA pacing with cycle lengths of 500 and 400 ms (210+/-18ms vs 245+/-14 ms, p<0.05; 207+/-23 ms vs 238+/-20 ms, p<0.05; respectively). The dispMAPD90 was significantly longer in the PAF group than in the control group during sinus and HRA pacing. The WAP value did not differ between the 2 groups. The minWLI in the PAF group was significantly smaller than that in the control group at HRA pacing with cycle lengths of 500 and 400 ms (3.3+/-0.5 vs 3.8+/-0.3, p<0.05; 3.2+/-0.4 vs 3.7+/-0.3, p<0.02). A shortened and widened dispersion of atrial refractoriness may play an important role in the genesis of AF. Furthermore, smaller wavelengths may form in the atrium of patients with PAF.

The role of hip arthroscopy in the evaluation of avascular necrosis.

This prospective study evaluated the correlation between plain radiographs, magnetic resonance imaging (MRI), and diagnostic arthroscopy in the staging of avascular necrosis of the femoral head. Fifty-two hips in 46 patients were prospectively staged using radiographic and MRI staging systems. Patients subsequently underwent hip arthroscopy to visualize the articular surface prior to considering salvage of the femoral head and debride delaminated osteochondral fragments. Weighted Kappa analysis revealed only moderate correlation between MRI and plain radiographs (K=.11), MRI and arthroscopy (K=.21), and plain radiographs and arthroscopy (K=.19). Six (46%) of 13 patients with a radiographically apparent subchondral fracture demonstrated collapse of the articular surface at arthroscopy. Four (24%) of 17 hips with >2 mm of collapse of the femoral head on plain radiographs demonstrated fragmentation of the osteochondral surface of the femoral head at arthroscopy. In 5 patients with flattening of the femoral head, 3 patients had delamination of both the femoral and acetabular surfaces. In regard to labral pathology, 5 of 22 post-collapse hips also had large bucket handle tears of the labrum. Arthroscopy of the hip revealed osteochondral degeneration that was not detected by plain radiographs or MRI in 36% of post-collapse femoral heads.

Hip arthroscopy using a limited anterior exposure: an alternative approach for arthroscopic access.

SUMMARY: Hip arthroscopy is a technically difficult procedure to perform. A limited anterior approach to the joint has made hip arthroscopy technically less difficult in our hands and has enabled us to treat a wide range of hip pathology. Five hip arthroscopies were performed using a modified 4-cm Smith-Petersen anterior approach to the hip exposing the joint capsule as manual traction is applied. The arthroscope is then easily introduced making visualization of the hip joint possible. The 5 hip arthroscopies resulted in either removal of loose bodies or debridement of an osteochondral fragment, synovitis, or cartilaginous debris. There were no complications postoperatively. We believe that hip arthroscopy through a limited anterior approach provides an easy and safe alternative method for arthroscopic access to the hip joint. Importantly, there is a decreased risk of neurovascular trauma and iatrogenic damage to the articular cartilage and acetabular labrum when introducing instruments into the hip joint.

Hip arthroscopy in staging avascular necrosis of the femoral head.

The purposes of this study were to evaluate how accurately current imaging modalities predict the quality of the articular surface in avascular necrosis (AVN) of the femoral head and to provide arthroscopic correlation to current staging modalities. An arthroscopic classification system, derived from the work of Marcus et al, was used to prospectively stage the articular surface in 23 hips with AVN using plain radiographs, magnetic resonance imaging (MRI), and arthroscopy. There was little correlation between all three diagnostic modalities. These findings were not statistically significant. Patients with stage IV disease had the widest variation in the appearance of the articular surface. This study shows poor correlation in the staging of AVN using current imaging techniques. Magnetic resonance imaging has been shown to be inadequate at assessing the articular cartilage. Therefore, either arthroscopy or direct visualization is required for accurate evaluation and staging, especially in stage IV disease.

The effect of knee and ankle position on displacement of Achilles tendon ruptures in a cadaveric model. Implications for nonoperative management.

Using a cadaveric model, we evaluated the effect of knee and ankle position on the displacement of the severed ends of an Achilles tendon transected at three different points. In six cadaveric legs the Achilles tendon was severed transversely, then marked with radiopaque wire suture. The distance between the wire markers was measured on radiographs taken in different positions of ankle and knee flexion. Ankle plantar flexion had a statistically significant effect on decreasing the gap between the severed ends of the Achilles tendon. This effect was clinically significant as, on average, the tendon edges were separated more than 20 mm when the ankle was in the neutral position and were apposed when the ankle was in 60 degrees of plantar flexion. With the ankle fixed in 60 degrees of plantar flexion, knee position had no significant effect on the displacement of the severed ends of the Achilles tendon. Overall, the effect of knee flexion was neither statistically significant nor clinically significant, as the increase in displacement of the severed ends of the Achilles tendon was only 3 mm from 0 degrees to 120 degrees of knee flexion. These results suggest that the nonoperative treatment of Achilles tendon ruptures requires immobilization in maximal ankle plantar flexion, and that immobilization of the knee may not be necessary to achieve tendon-edge apposition.

The relation between the pacing sites in the right ventricular outflow tract and QRS morphology in the 12-lead ECG.

Optimal pace mapping is a good predictor of the appropriate ablation site for idiopathic right ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT). We studied the relationship between the RVOT pacing site and QRS morphology in the 12-lead ECG during pacing to find the optimal site more quickly. In 13 patients with idiopathic VT, pacing at 8 sites in the RVOT (free wall, septum, and anterior and posterior regions of upper and lower sites) was performed while 12-lead ECGs were recorded. The R-wave amplitude minus the S-wave amplitude in lead I (RI-SI) and aVF (RavF-SavF) and the transitional zone index (TZI) were compared in the different pacing sites; TZI was defined to examine the transitional zone as a value. The RI-SI was smaller in the anterior region than in the other regions, and the negative RI-SI predicted that the pacing site was in the upper or lower anterior regions. The RavF-SavF was larger in the septum and anterior regions than in the free wall and posterior regions. The TZI was larger in the free wall region than in the septum. From the results, we constructed a flow chart that differentiates the origin of the arrhythmia in the RVOT and a directional guide that indicates the direction from the current mapping site for optimal pace mapping. The results provided an ECG guide for locating the focus of VT originating from the RVOT. These findings may systematically improve the mapping procedure.

Congenital pseudarthrosis of the tibia treated with free vascularized fibular graft.

Management of patients with deformities due to congenital pseudarthrosis of the tibia continues to be controversial. The use of free vascularized fibular grafts in the reconstruction of these deformities appears to be successful in this patient population but is not without potential for significant complications. Long-term evaluation, at least to skeletal maturity, is necessary to judge the success of any procedure done for any pediatric patient. This case illustrates the natural history of the vascularized free fibular graft for congenital pseudarthrosis of the tibia in a young child. Complications of this treatment modality did occur, including probable recurrence and fracture at almost 11 years post-index procedure. However, stable reconstruction leading to fracture union was achieved, and the patient has resumed full activities with little residual deformity.

Escherichia coli O157:H7 in livestock in Japan.

The largest ever outbreak in Japan of Escherichia coli O157 infection in humans occurred in 1996. As a result, surveys were conducted later the same year to evaluate the sources and pathogenesis of this bacillus in livestock animals at the farm and in abattoirs. One of the surveys resulted in the isolation of E. coli O157 in 0.62% of cattle on randomly selected farms. Although no confirmation has been made with regard to the source of E. coli O157 infection and its pathogenicity in livestock animals, preventive measures are being applied at both farm and processing levels.

Non-radioactive adenosine 5'-phosphosulfate sulfotransferase assay by coupling with sulfite reductase and O-acetylserine(thiol)lyase.

Adenosine 5'-phosphosulfate (APS) sulfotransferase is thought to be an enzyme that transfers the sulfo-group of APS to a carrier compound with a thiol group in the assimilatory sulfate reduction pathway of higher plants. We developed a rapid, non-radioactive assay for APS sulfotransferase. Sulfite released by APS sulfotransferase reaction in the presence of excess dithiothreitol was further converted to cysteine by coupling with yeast sulfite reductase and cabbage O-acetylserine(thiol)lyase. The cysteine thus formed was measured colorimetrically. By this method, 5 to 300 nmol of sulfite could be assessed. When the method was applied to APS sulfotransferase, the enzyme activity was APS-dependent with the partially purified enzyme. We could also detect APS sulfotransferase activity in some higher plants by this method.

Long term follow-up of medial column fusion and tibialis anterior transposition for adolescent flatfoot deformity.

We report the results of three patients (four feet) who had surgical correction of adolescent flatfeet performed over fifty years ago. The surgery involved medial column stabilization with fusion procedures and tibialis anterior transposition into the navicular (Young's tenosuspension procedure). In this small sample, we found a high rate of painful arthrosis that developed over time in the contiguous joints of the foot.

Purification and Characterization of Cystine Lyase a from Broccoli Inflorescence.

One of the three isoforms of an enzyme degrading L-cystine was purified to homogeneity from broccoli (Brassica oleracea var. italica) inflorescences, with use of a sensitive assay based on derivatization of a reaction product with monobromobimane. The reaction product with a thiol group was found to be thiocysteine from results of liquid chromatography-mass spectrometry and high-resolution mass spectrometry. Pyruvate was also a reaction product, formed in equimolar amounts. The purified enzyme catalyzed ß-elimination of L-cystine to yield thiocysteine, pyruvate and possibly ammonia, so it was cystine lyase a. L-Cystine but not D-cystine was a substrate of the enzyme. S-Methyl L-cysteine sulfoxide and S-ethyl L-cysteine sulfoxide were substrates but were less suitable than L-cystine. L- and D-cysteine and also cystathionine were not substrates. The purified enzyme (Mr 186,000) was composed of four identical subunits (Mr 45,000) and was pyridoxal 5'-phosphate-dependent.

Tissue specificity of mitochondrial F0F1-ATPase activity of Lilium longiflorum plant.

A large difference was found in the activities of oligomycin-sensitive mitochondrial F0F1-ATPase isolated from different tissues of Lilium longiflorum plants. The enzyme activity of F0F1-ATPase in pollen was the highest, while that in bulbs was the lowest. When ATPases were cross-reconstituted from F1-ATPases and F1-depleted submitochondrial particles (SMP), ATPases reconstituted from F1-depleted pollen SMP showed the higher activity regardless of the source of F1-ATPase. Fatty acid compositions of phospholipids in SMP were also different between bulbs and pollen. These suggest that the F0 portion and/or its environment are important for regulation of F0F1-ATPase activity in L. longiflorum plant.

Resistance to injury by sulfur dioxide : correlation with its reduction to, and emission of, hydrogen sulfide in Cucurbitaceae.

In Cucurbitaceae young leaves are resistant to injury from acute exposure to SO(2), whereas mature leaves are sensitive. After exposure of cucumber (Cucumis sativus L.) plants to SO(2) at injurious concentrations, illuminated leaves emit volatile sulfur, which is solely H(2)S. Young leaves emit H(2)S many times more rapidly than do mature leaves. Young leaves convert approximately 10% of absorbed [(35)S]SO(2) to emitted [(35)S]H(2)S, but mature leaves convert less than 2%. These results suggest that a high capability for the reduction of SO(2) to H(2)S and emission of the H(2)S is a part of the biochemical basis of the resistance of young leaves to SO(2).

Emission of Hydrogen Sulfide by Leaf Tissue in Response to l-Cysteine.

Leaf discs and detached leaves exposed to l-cysteine emitted a volatile sulfur compound which was proven by gas chromatography to be H(2)S. This phenomenon was demonstrated in all nine species tested (Cucumis sativus, Cucurbita pepo, Nicotiana tabacum, Coleus blumei, Beta vulgaris, Phaseolus vulgaris, Medicago sativa, Hordeum vulgare, and Gossypium hirsutum). The emission of volatile sulfur by cucumber leaves occurred in the dark at a similar rate to that in the light. The emission of leaf discs reached the maximal rate, more than 40 picomoles per minute per square centimeter, 2 to 4 hours after starting exposure to l-cysteine; then it decreased. In the case of detached leaves, the maximum occurred 5 to 10 h after starting exposure. The average emission rate of H(2)S during the first 4 hours from leaf discs of cucurbits in response to 10 millimolar l-cysteine, was usually more than 40 picomoles per minute per square centimeter, i.e. 0.24 micromoles per hour per square decimeter. Leaf discs exposed to 1 millimolar l-cysteine emitted only 2% as much as did the discs exposed to 10 millimolar l-cysteine. The emission from leaf discs and from detached leaves lasted for at least 5 and 15 hours, respectively. However, several hours after the maximal emission, injury of the leaves, manifested as chlorosis, was evident. H(2)S emission was a specific consequence of exposure to l-cysteine; neither d-cysteine nor l-cystine elicited H(2)S emission. Aminooxyacetic acid, an inhibitor of pyridoxal phosphate dependent enzymes, inhibited the emission. In a cell free system from cucumber leaves, H(2)S formation and its release occurred in response to l-cysteine. Feeding experiments with [(35)S]l-cysteine showed that most of the sulfur in H(2)S was derived from sulfur in the l-cysteine supplied and that the H(2)S emitted for 9 hours accounted for 7 to 10% of l-cysteine taken up. (35)S-labeled SO(3) (2-) and SO(4) (2-) were found in the tissue extract in addition to internal soluble S(2-). These findings suggest the existence of a sulfur cycle which converts l-cysteine to SO(4) (2-) through cysteine desulfhydration.