Yoshihiko Igarashi

Incipient chordoma : a report of two cases of early-stage chordoma arising from benign notochordal cell tumors

Chordomas are rare malignant bone tumors primarily involving both ends of the axial skeleton that present as destructive bone lesions with a large soft tissue mass. Chordomas were previously believed to arise from notochordal remnants. However, recent studies suggest the possibility that chordomas arise from benign notochordal cell tumors. We present two cases of coccygeal incipient chordoma that strengthen the new hypothesis. The first case was an 83-year-old man who died of prostatic adenocarcinoma. The second case was a 79-year-old man who died of hepatocellular carcinoma. The coccygeal tumors were composed of intraosseous and extraosseous infiltrative lesions. The intraosseous lesions consisted of both benign notochordal cell tumor and incipient chordoma. The extraosseous lesions were consistent with incipient chordoma. In addition, two other small benign notochordal cell tumors were found at a different level in case 1. It is conceivable that pre-existing intraosseous benign notochordal cell tumors transform into incipient chordoma and then extend through the cortex into the surrounding soft tissue. The incidence of incipient chordoma appears much higher than expected because chordomas are rare tumors with an incidence of one case per 1 000 000 persons per year. We suspect that unknown factors transform incipient chordoma into classic chordoma.

Acid phosphatases as markers of bone metabolism.

Various biochemical markers have been used to assess bone metabolism and to monitor the effects of treatments. Tartrate resistant acid phosphatase (TRAP; EC 3.1.3.2) has often been used to assess bone absorption. Although osteoclasts contain abundant TRAP and they are responsible for bone resorption, the total TRAP activities in the serum measured by colorimetric methods little reflect the bone turnover. TRAP 5 is further separated into 5a and 5b by electrophoresis. Type 5b is considered to be derived from the osteoclast, and therefore attempts are being made to measure exclusively serum TRAP 5b by kinetic methods, immunological methods, and chromatographic methods including ion-exchange and heparin column chromatography.

Heparin column analysis of serum type 5 tartrate-resistant acid phosphatase isoforms

The objective of the present study was to develop a specific method for the separation of tartrate-resistant acid phosphatase (TRAP) derived exclusively from osteoclasts. Heparin column-bound TRAP in human serum was separated into three peaks of TRAP activity when eluted with a linear gradient of sodium chloride. The last peak corresponded to TRAP 5b which was first named according to its electrophoretic mobility [Clin. Chem. 24 (1978) 309] and was considered to be derived from osteoclasts [J. Bone Miner. Res. 13 (1998) 683]. The second peak was found to be TRAP 5a. The height of the last peak varied from age to age.

Stopped‐flow apparatus for x‐ray scattering at subzero temperature

A stopped‐flow apparatus was constructed for x‐ray scattering study at subzero temperature. It can be operated over a wide temperature range down to −20 °C with highly viscous solution (20 cP) successfully. We have applied the stopped‐flow x‐ray scattering method to many biological reactions. In particular, the association of E. coli ribosomal subunits was detected at −10 °C which was too fast to be detected at room temperature. Dissociation of E. foetida hemoglobin was measured by the stopped‐flow x‐ray scattering method combined with a time‐resolved imaging plate as a detector.

Solution X-ray scattering study on the chaperonin GroEL from Escherichia coli

The molecular architecture of native GroEL has been studied by solution X-ray scattering. The radius of gyration for the native molecule was estimated to be 66.0 A in 50 mM Tris-HCl, 100 mM KCl at pH 7.5 and 25 degrees C. The maximum dimension was estimated to be 170 A, based on the pair distance distribution function. A cylindrical structure or two heptameric rings was found to be the best for native GroEL among structures examined by using a multi-sphere model analysis in which the radius of constituent sphere was 6 A. The results of the model analysis show that the radius of GroEL is 68.0 A and the height is 150.7 A. Unexpectedly, the central penetrating hole through GroEL was not confirmed in the best-fit structure.

Hill and Scatchard plots of Daphnia magna hemoglobin

Abstract The oxygen equilibrium curve of Daphnia magna hemoglobin (Hb) was measured accurately with an automatic recording apparatus. According to an Adairs octomerous equation, eight Adairs constants were determined by curve fitting. The Hill and Scatchard plots for binding of oxygen (O 2 ) to Daphnia Hb were performed and their slopes calculated. The Hill plot of Daphnia Hb was characterized by a double-peak-like pattern. These were compared to those of human Hb, and the O 2 binding characteristics of Daphnia Hb discussed.

Dissociation of Limulus polyphemus (horseshoe crab) hemocyanin. I. Solution X-ray scattering study in equilibrium.

A solution X-ray scattering study has been performed on Limulus polyphemus (horseshoe crab) hemocyanin and its dissociated fragments at various pH values in the presence and absence of Ca2+. The scattering patterns of native hemocyanin (48-mer), the half molecule (24-mer), quarter molecule (12-mer) and monomer fraction were measured. The radii of gyration for the four molecular species were calculated from the Guinier plots to be 110.7, 91.3, 77.3, and 36.5 A, respectively. Models which yield good fits to the experimental data are presented. The models were constructed using eight, four and two spheres with a radius of 58 A, assuming the sphere to be the submultiple composed of six subunits. The radii of gyration were calculated on the basis of the model and the values found to be 106, 94 and 73 A, respectively, in good agreement with the experimental results.

Calcium Dependent Allosteric Modulation and Assembly of the Giant Hemoglobin from the Earthworm, Eisenia Foetida

Extracellular hemoglobins(Hb) from annelids have been known to show no heterotropic interaction with the organic phosphate, such as 2,3-diphosphoglycerate. In an attempt to investigate allosteric effectors of annelid Hb, we estimated the oxygen equilibrium of Eisenia Hb and found that Ca plays an important role on the modulation of the oxygen affinity and cooperativity, as a result of the binding to the oxy-form of the Hb, under a physiological range of Ca concentration(1).

Dissociation of Limulus polyphemus (horseshoe crab) hemocyanin. II. Stopped-flow X-ray scattering study

Abstract Dissociation kinetics of Limulus polyphemus hemocyanin, induced by calcium removal was studied by the stopped-flow X-ray scattering (SFXS) method and fluorescence stopped-flow method at various pH. Between pH 6.3 and 8.4, the time course of the kinetics showed a lag followed by a single exponential decay, while it obeyed a single exponential decay without a lag at pH 8.8. To analyze the process, equations to calculate zero angle intensity, I 0 , and radius of gyration, R g , were presented. Simulated curves from the equations fitted the data well. Concerning either of I 0 and R g , the lag-time decreased with increasing EDTA concentration, while the apparent rate constant of the dissociation, k app , increased. Based on the value of I 0 and R g at infinite time, it is most likely that the observed kinetics between pH 6.3 and 7.9 reflects the dissociation of the protein (48-mer) into two equal halves (24-mer), for which a sequential two-step reaction was suggested. On the other hand the kinetics above pH 8.0 indicated the dissociation into constituent subunits.

Analysis of Oxygen Equilibrium Using the Adair Model for the Hemocyanin of Limulus polyphemus and the Hemoglobin of Eisenia foetida

Oxygen equilibrium curves of arthropod He and annelid Hb consisting of multiple subunits have been analyzed using the two-state model of Monod- Wyman-Changeux (MWC) and its extensions (1-4). However, it remains unclear whether these molecules undergo R-T transition in their conformation. In the absence of direct structural evidence, it would seem somewhat controversial to apply the MWC model. The Adair scheme seems to be a better choice for representing the cooperativity of the highly assembled 02-carrying proteins because it is a more general description of the ligand equilibria of O2 carriers (5). This equation requires only that the binding sites in the consecutive steps of oxygenation be assumed to be functionally identical. However, only a few attempts have been made to apply the Adair model to giant respiratory proteins (6) because of the difficulty caused by the large number of 02-binding sites. Relative to the MWC model, the Adair model has the advantage of showing cooperativity by Adair parameters at equilibrium without any consideration of R and T conformation of the 02-binding protein.