The structure of cucurbitin: subunit symmetry and organization in situ

The low-resolution (2 nm) subunit symmetry of cucurbitin, the crystalline seed storage globulin of cucurbits, has been determined by X-ray diffraction. The wet crystals belong to the cubic space group F23 and there are 4 molecules per unit cell. The molecules therefore possess point-group symmetry 23 and contain 12 structural units which at this resolution are indistinguishable. On drying, the crystal lattice dimension shrinks from 13.6 nm to 12.4 nm with no apparent change in symmetry. Diffraction patterns of small crystals spun into a pellet, and sections of dry and wet native seed indicate that in situ the protein is organised in microcrystals of the same unit cell and symmetry. Edestin, the crystalline storage globulin from cannabis, and a crystalline globulin from tobacco seed both have the same crystal lattice as cucurbitin and, very likely, the same subunit symmetry.     

Effect of sulfasalazine on B cell hyperactivity in patients with rheumatoid arthritis

OBJECTIVE: We investigated the in vitro immunomodulatory effects of sulfasalazine on B cells in rheumatoid arthritis (RA). METHODS: Reversed hemolytic plaque assay and 3H-thymidine incorporation were measured. RESULTS: B cells from patients with RA showed hyperactivity to stimulation by Staphylococcus aureus Cowan I. Sulfasalazine significantly inhibited this B cell hyperactivity in a dose dependent manner. The kinetic study and a decrease in 3H-thymidine incorporation on Day 3 indicate that sulfasalazine inhibited the early phase (0-48 h) of B cell proliferation in these patients. Sulfapyridine also inhibited B cell hyperactivity in these patients, but 5-aminosalicylic acid and N-acetylsulfapyridin had no significant effect. CONCLUSION: Sulfasalazine exhibited a direct immunosuppressive effect on B cell hyperactivity in patients with RA, which may be responsible for its therapeutic effectiveness in this disorder.     

Surface alterations of the bovine oocyte and its investments during and after maturation and fertilization in vitro

Surface characteristics of the bovine oocyte and its investments before, during, and after maturation, and fertilization in vitro were evaluated by scanning electron microscopy (SEM). Oocyte diameters were also measured during SEM analysis of the oocyte. The cumulus cells manifested a compact structure with minimal intercellular spaces among them in the immature oocytes. These became fully expanded with increased intercellular spaces after maturation in vitro, but contracted again after fertilization. The zona pellucida (ZP) showed a fibrous, open mesh-like structure in the maturing and matured oocytes. The size and number of meshes on the ZP decreased dramatically after fertilization. The vitelline surface of immature oocytes was characterized by distribution of tongue-shaped protrusions (TSPs) varying in density. After 10 and 22 hr of maturation incubation, oocyte surface microvilli (MV) increased to become the predominant surface structure, and TSPs decreased substantially. The vitelline surface of fertilized oocytes (at 6 and 20 hr) was similar to that of the matured oocytes, but unfertilized oocytes had less dense MV than did fertilized oocytes (at 20 hr). The diameter of the oocytes decreased from 99 to 80 microns during maturation and increased to 106 microns after insemination (P < 0.05). Membrane maturation was characterized by surface changes from a TSP-predominant pattern to a MV-predominant pattern. Thus, the bovine oocyte maturation process was found to involve the expansion of cumulus cells and the maturation of the ZP, which changes dramatically upon fertilization. Also, volumetric changes occurred in ooplasm processed for SEM following oocyte maturation and insemination.     

Vertical seismic response of overhead crane

Vertical seismic response behavior is an important issue for the seismic design of equipments. The equipment, which is comparatively soft and unrestrained vertically, may resonate and its response is significantly magnified under vertical seismic excitation. Overhead crane is an example of equipment that is unrestrained vertically. The dynamic behavior of an 150-ton-capacity overhead crane under vertical seismic excitation was investigated by scale model excitation test and nonlinear time history analysis. The excitation tests were performed with several input levels and the vertical response with each input level was obtained. The simulation analysis approximately corresponded to the results of the excitation test.     

Kinetic analysis of propranolol-induced impairment of its own metabolism in rats

The effect of repetitive oral administration of propranolol (100 mg kg-1 day-1, 5 days) on the kinetics of liver microsomal propranolol metabolism was investigated in the rat. Vmax values of the high-affinity phase for biphasic kinetics of propranolol 4- and 5-hydroxylase activities were decreased by propranolol pretreatment, while those of the low-affinity phase were unchanged. The Vmax value of monophasic 7-hydroxylase activity was also decreased. On the other hand, the Vmax value of N-desisopropylase activity in the propranolol-treated rats was increased more than 2-fold compared with non-treated (control) rats, resulting in a change from monophasic in control rats to biphasic kinetics in propranolol-treated rats. These findings indicate that repetitive administration of propranolol selectively impairs a CYP2D isozyme that is involved in the high-affinity phases for propranolol ring-hydroxylations.     

Evaluation of transmitral flow velocity profile in supine and sitting positions by pulsed Doppler echocardiography in elderly hypertensives

To evaluate left ventricular diastolic filling properties in elderly hypertensive case with left ventricular hypertrophy (LVH), we investigated the influence of postural change from a supine to sitting position on transmitral flow velocity profile as assessed by pulsed Doppler echocardiography in 12 normotensives (N group) and 24 hypertensives, aged 65 to 80 years. Hypertensive subjects were divided into two groups on the basis of left ventricular mass index (LVMI): 12 hypertensives without LVH (H1 group; LVMI < 130 g/m2); 12 hypertensives with LVH (H2 group; LVMI > 130 g/m2). Peak early filling velocity (E), peak atrial filling velocity (A) and the E/A ratio were similar in the three groups in the supine position. The postural change decreased E and A in N and H1 groups. On the other hand, the change decreased E, but not A in the H2 group. The E/A ratio was decreased in the H2 group compared with both the N and H1 group in the sitting position. As a result, the sitting position increased atrial contribution to diastolic filling in the H2 group. These observations indicate that a reduction in preload changes the transmitral flow velocity profile in elderly hypertensives with left ventricular hypertrophy. The Doppler alterations may be related to impaired left ventricular diastolic function.     

Influence of refraction on the visual field defects in normal tension glaucoma and primary open angle glaucoma eyes

The prevalence of normal tension glaucoma (NTG) or primary open angle glaucoma (POAG) is higher in myopic populations and the prevalence of myopia and NTG is relatively high in the Japanese. To evaluate the influence of myopic refractive error on the central visual field defect in NTG eyes, the data obtained from NTG eyes with the Humphrey Visual Field Analyser were analysed in comparison with those from POAG eyes. One hundred and twenty NTG eyes and one hundred and ninety-seven POAG eyes were included. All of them had clear ocular media, but no myopic degeneration in the fundus. Multiple linear regression analysis was performed with a dependent variable of the deviation of the measured threshold value from normal reference value (total deviation, STATPAC) and independent variables of refractive error and mean deviation (STATPAC). Myopic power was found to be positively correlated with the depression in the lower papillo-macular area in both NTG and POAG eyes, and it was negatively correlated with the depression in an upper arcuate area extending just nasal to the fixation only in NTG eyes.     

The design of a precompensator for multivariable adaptive control-anetwork-theoretic approach

A network-theoretic approach to the design of a dynamic precompensator C(s) for a multiinput, multioutput plant T(s) is considered. The design is based on the relative degree of each element of T(s). Specifically, an efficient algorithm is presented for determining whether a given plant T(s) has a diagonal precompensator C( s) such that, for almost all cases, T(s)C (s) has a diagonal interactor. The algorithm also finds any optimal precompensator, in the sense that the total relative degree is minimal. The algorithm can be easily modified to work even when a T(s) represented by a nonsquare matrix is given     

The effect of excess gate current on input impedance of a JFET amplifier

When JFET is used as an amplifier, it should be regarded that the effect of excess gate current on the input impedance is changed by gain of the amplifier. The input impedance or conductance with gain of the JFET amplifier is experimentally analyzed applying small signal equivalent circuit.