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The cerebral fat embolism is a potentially serious complication of fractures but clinical cases often go undiagnosed. Two cases of clinically diagnosed cerebral fat embolism are reported, and MR images of these patients are described. While brain CT revealed no abnormality, MR imaging showed relative low-intensity areas on T1-weighted images and high-intensity areas on T2-weighted images. In one patient follow-up MR showed nearly complete resolution of the abnormal signal. MR imaging appears to be valuable for detecting the lesions in these patients.

In order to understand the role of Cys53 and Cys165 of human growth hormone (hGH) in receptor-binding and biological activity, artificial mutant variants of hGH were prepared in Escherichia coli by in vitro mutagenesis. Variants of hGH were constructed by replacement of Cys165 with Ala ([Ala165]hGH) or Ser ([Ser165]hGH), by replacement of Cys53 with Ala ([Ala53]hGH), by replacement of Cys53 and Cys165 with Ala ([Ala53, Ala165]hGH), or by replacement of Cys53 with Ala and Cys165 with Ser ([Ala53, Ser165]hGH). All of the variants constructed as well as reduced hGH exhibited less biological activity than that of intact hGH, and the decreases in biological activity were almost equal, as measured by a sensitive biological assay for growth hormone : adipose conversion assay using 3T3-F422A cells. These variants also showed less receptor-binding activity than that of intact hGH.These results suggest that it is possible neither the residue Cys53 nor Cys165 is directly involved in the receptor binding, and that the disulfide bridge between Cys53 and Cys165 in hGH may not always be crucial for the biological activity, though necessary to express full hGH activity.

Summary In order to elucidate the active sites of growth hormone for eliciting the differentiation of preadipose 3T3-F442A cells to adipocytes, four artificial mutant variants of human growth hormone(hGH) modified in the loop region of amino acid residues 54–74 were prepared in Escherichia coli by site-directed mutagenesis. Although the P59A (replacement of Pro59 with Ala) variant retained almost the same biological- and receptor binding-activity as hGH, the P61A (replacement of Pro61 with Ala) and the P59A–P61A (replacement of both Pro59 and Pro6l with Ala) both exhibited about half the activity, and the Δ (62–67) variant (deletion of the residues 62–67) exhibited only about 0.1% the activity of those of intact hGH. The results suggest that Pro61 may be involved in formation of the active conformation of hGH, but Pro59 may not, and that the amino acid residues around 62–67 may be critical for the specific biological features of hGH.

Starch-utilizing mutants of Escherichia coli which can grow well on starch or amylose as the sole carbon source were isolated. The maximal viable cell number of the starch-utilizing mutants on the polysaccharide media reached the same level (4 × 109 cells/ml) as that with glucose medium after incubation for 24 hours at 37°C. The isolated mutants could produce more intracellular α-amylase than the wild-type strain, and the enzyme activity was detected in the extracellular fluid. Polyacrylamide gel electrophoresis showed that the intracellular and extracellular enzymes had similar electrophoretic mobilities. These observations suggested that the ability of growth on the polysaccharide media was due to the excreted α-amylase, which appeared to be identical with the intracellular enzyme.

Intracellular concentrations of phosphoenolpyruvate (PEP) and five kinds of allosteric effectors (acetyl-CoA, fructose 1,6-bisphosphate, GTP, L-aspartate, and L-malate) of PEP carboxylase were measured in E. coli cells grown on various compounds as a carbon source. Based on the data obtained, reaction systems which contained a definite concentration of the enzyme and the ligands at the concentrations found in vivo were constructed and the enzyme activities were measured. The ratio of each activity thus obtained to the maximal activity attainable with the same concentration of enzyme and saturating concentrations of the activators was estimated. For the cells grown on glucose, glycerol, or lactate, the extent of exhibition of the enzyme activity was 2-15% of the maximal activity. For the cells grown on acetate or oleate, the extent was 1-3%. For the cells grown on succinate, L-aspartate, L-malate, or glucose plus L-aspartate, the extent was less than 0.4%. Consideration of the data obtained in the present studies, together with those obtained in our previous studies on the enzyme level (Teraoka, H. et al. (1970) J. Biochem. 67, 567-575), showed that the control of the enzyme reaction in vivo is considerably different from that expected from the in vitro experiments, and that deficiencies of "coarse control" are covered by a "fine control."

In an attempt to clarify the kinetic properties of Escherichia coli phosphoenolpyruvate (PEP) carboxylase [EC 4.1.1.31] in vivo and to evaluate the physiological significance of the individual effectors, saturation curves were obtained for each ligand with reaction mixtures (pH 7.3) containing "physiological concentrations" of the other ligands in various combinations. As the "physiological concentrations" of ligands, which are defined as the concentrations of ligands found in the glucose-grown cells, the following values were employed: PEP, 0.2 mM; acetyl-CoA(CoA-SAc), 0.4 mM; fructose 1,6-bisphosphate(Fru-1,6-P2), 2.0 mM; GTP, 1.0 mM; L-aspartate, 1.0 mM; L-malate, 1.0 mM (Morikawa, M., Izui, K., Taguchi, M., & Katsuki, H. (1980) J. Biochem. 87, 441--449). In the absence of any activator the enzyme activity was very low. CoASAc was the most powerful activator. The other two activators (Fru-1,6-P2 and GTP) exhibited essentially no activation alone, but produced a strong synergistic activation with CoASAc. The severe inhibition by L-aspartate or L-malate was effectively alleviated only through this synergistic action of the activators. The presence of all three activators decreased the half-saturation concentration (S0.5) of PEP from 15 mM to 0.35 mM and increased the maximal velocity attainable at infinite concentration of PEP about 15-fold. In the system containing all five effectors, which is close to the in vivo condition, the saturation curve of PEP was sigmoidal with a Hill coefficient of 1.6 and with an S0.5 value of 3.0 mM, which is about 15-fold larger than its "physiological concentration." On the basis of the rate-concentration curve for each effector obtained with the reaction mixture containing PEP and the other effectors at "physiological concentrations," it was suggested that all five effectors significantly contribute to the enzyme activity in vivo. Palmitoleate, another activator of the enzyme, showed no activation in such a reaction mixture. The sensitivity of the enzyme to the "physiological concentration" of each effector was also observed in an in situ system using permeabilized E. coli cells, where the enzyme concentration was as high as in vivo.

Particulate preparations obtained from cells of yeast Saccharomyces sake have been shown to possess glycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase activities. Glycerolphosphate acyltransferase exhibits a high specificity for saturated and monoenoic fatty acyl-CoA thioesters. When palmitoyl-CoA is employed as sole acyl group donor, the major lipid product is lysophosphatidic acid. 1-Acylglycerolphosphate acyltransferase of this yeast species has a rather strict specificity for monoenoic fatty acyl-CoA thioesters as acyl donor. These two acyltransferases are strongly inhibited in vitro by low concentrations of free fatty acids. 1-Acylglycerolphosphate acyltransferase is much more susceptible to fatty acid inhibition than glycerolphosphate acyltransferase. The inhibition is dependent not only on the concentration of fatty acid, but also on the length of exposure to fatty acid. Both saturated and unsaturated fatty acids inhibit the acyltransferase activities. The inhibitory effects of fatty acids cannot be ascribed to a nonspecific surfactant action of fatty acids. The present results support the view that free fatty acid serves as a regulator of glycerolipid synthesis.

The focusing properties of the multi‐stage system of weak lenses, such as in the accelerating tubes, are considered. The lens system is treated as one thick lens in the paraxial ray approximations. By assuming that the field distribution of each lens is the same, the simple expressions for the focal lengths and the locations of the focal points of this lens system as a whole are given.

The effect of mutational alteration of phosphoenolpyruvate (PEP) carboxylase on sensitivity to four kinds of allosteric effectors was studied. In several mutants the enzyme was differentially and independently desensitized to each of the effectors, indicating the existence of at least four distinct binding sites for the effectors. Mutants, whose enzyme was desensitized not only to one effector but also to two or three effectors in combination were obtained with a high frequency.

The approximate formulas of cardinal elements of strong coaxial two‐cylinder lenses are given by modifying the methods of Grivet et al. and of Felici. The basic idea used by them is to approximate the function T(z) in the path equation by the one which has the same area and abscissa of the center of gravity as T, and which gives exact solutions. Various modified methods of approximating this function, by a proper choice of the width of the replacing function, are given. New formulas are applied to several cases and it is shown that certain modifications, such as replacing T with a rectangular variation and making its width equal to the width at 1/4 the height of T, results in rather small errors. For example, the errors of the average focal length and the locations of the focal points in a two‐cylinder lens are smaller than 0.01 in units of the diameter of the cylinder for φ2/φ1≲20.

The approximate polynomials to the focal constants of equidiameter coaxial two‐cylinder lenses are given by making use of the methods which are used to approximate elementary functions for computer applications. The range of voltage ratio Φ2/Φ1 of two cylinders are taken as 1/20≲Φ2/Φ1≲20. The polynomials obtained by Chebyshev expansions are better than those obtained by Taylor expansions. The convergence of the expansion depends greatly on the choice of the expansion parameters (arguments) as well as on its range. The polynomials of the 8th degree, obtained from the partial sums of Chebyshev expansions with the parameter x=½ log(Φ2/Φ1), give smaller relative errors than 2×10−4 in the above range for the focal constants of the lenses with typical axial potentials.

Die relativistischen und nichtrelativistischen Kardinalelemente von Zweirohr-Immersionslinsen wurden verglichen. Unsere Ergebnisse unterscheiden sich von denjenigen vonE. B. Baset al.

A method is given for calculating the potential distribution of a system consisting of two coaxial cylinders, each of unit radius, separated by a distance of 2a along the axis. The potentials of the left‐ and right‐hand cylinders are taken as −1 and +1, respectively. The problem can be solved if the potential φ(1,z) on r = 1 or its inverse Fourier sine transform A(λ) is obtained. The dual integral equations for A(λ) are derived from the boundary condition on the cylinders and the continuity condition of the potential and of its normal derivative on the gap (r = 1, |z|≤a) between the cylinders. The solution A(λ) is expressed by the following series: A(λ)=2πJ0(λa)λ+ ∑ n=1∞anJ2n(λa)λ. The coefficients an in this series satisfy an infinite set of linear equations. The values of an for several values of the half‐gap length a are calculated by successive approximations and are shown in a table.

Growth hormone increases tissue formation by acting both directly and indirectly on target cells. The direct action promotes the differentiation of precursor cells; this has been demonstrated for two mesenchymal cell types. Insulin-like growth factor I (IGF-I) is not able to substitute for growth hormone in promoting this differentiation, but it is proposed that its mitogenic action selectively promotes cell multiplication in young differentiated clones. As tissue growth results from both the creation of new differentiated cells and their subsequent clonal expansion, both effectors increase tissue growth, but by different means.

Four artificial mutant variants of human growth hormone (hGH) with the following characteristics were prepared in Escherichia coli by in vitro mutagenesis: (i) replacement of Trp86 with Tyr (W86Y hGH); (ii) deletion of Trp86 (delta W86 hGH); (iii) deletion of residues 32-46 (20-kd-hGH); and (iv) deletion of residues 32-71 (17.5-kd-hGH). Both W86Y hGH and delta W86 hGH have a point mutation at Trp86 which is the only Trp residue in hGH and is conserved among members of the growth hormone family. 20-kd-hGH is a minor component of hGH in the pituitary gland and plasma and is the result of an alternative splicing of the primary gene transcript, while only the corresponding mRNA and not the protein has been found in the case of 17.5-kd-hGH. The biological activities (adipogenic activity and potentiation of gain in body weight) and structures (as analyzed by circular dichroism) were mostly retained by the W86Y, delta W86 and 20-kd-hGH variants but not by 17.5-kd-hGH.

Cultured preadispose 3T3 cells are able to undergo a process of differentiation through which they are converted into adipose cells. Growth hormone induces this conversion in resting cultures but not in growing cultures. It was of interest to determine the period of cell sensitivity to the hormone and the timing of the induction of glycerophosphate dehydrogenase, a key enzyme in lipogenesis. It was found that 3T3-F442A cells became highly sensitive to rat growth hormone at confluence but that high sensitivity remained for only 3 days; thereafter, the responsiveness to the rat growth hormone declined rapidly. Refeeding of the cells with fresh medium did not lead to the recovery of the hormone sensitivity, indicating that the decrease in sensitivity was not due to exhaustion of medium components but that it seemed to be a specific property of F442A cells. As glycerophosphate dehydrogenase activity was detected at nearly the same time as its mRNA was measurable, it is likely that the mRNA is translated immediately after its synthesis.

Cultured preadipose 3T3 cells are induced or enabled to undergo adipose conversion in the presence of an extract of pituitary gland. Adipogenic activity is found in standard growth hormone preparations derived from different species. Further purification of rat growth hormone by several methods does not remove its adipogenic activity. Human growth hormone synthesized in Escherichia coli is also effective. Adipogenic activity is not associated with other pituitary polypeptides. Since growth hormone acts on preadipose cells in the absence of any other cell type, a mechanism exists for the direct participation of the pituitary gland in the regulation of this form of mesenchymal differentiation.

Phosphoenolpyruvate carboxylase of Escherichia coli was found to be remarkably activated by free fatty acid, such as laurate and oleate, and by its CoA derivative. The regulatory site of the enzyme for binding with these compounds was discriminated from the site for acetyl-CoA (one of the allosteric activators, on the basis of the isolation of the mutant having the altered phosphoenolpyruvate carboxylase which is almost insensitive to these compounds but still sensitive to acetyl-CoA. Physiological significance of this activation was also discussed.

The aim of this study was to assess the performance of three-dimensional fast recovery fast spin-echo (3DFRFSE) for imaging of the inner ear as well as the facial and vestibulocochlear nerves. We evaluated 3DFRFSE sequences, comparing it with 3D fast spin-echo (3DFSE) in a water phantom and in 12 normal volunteers. We also examined 66 patients using 3DFRFSE sequence and assessed the visualization of their pathologies. In a water phantom study, signal intensity (SI) on 3DFRFSE was higher than that on 3DFSE at the same TR ranging from 1,500 to 6,000 ms. In normal volunteers, 3DFRFSE with TR of 2,800 ms showed comparable SI, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) superior to those on 3DFSE with TR of 5,000 ms. In clinical setting, 3DFRFSE was useful in demonstrating anatomic details in the labyrinth and pathologic findings of inner ear. The 3DFRFSE can provide high-resolution heavily T2-weighted images (T2WI) with shorter scan time than 3DFSE without significant disadvantage. The 3DFRFSE is a beneficial technique for evaluation of lesions in the inner ear as well as the facial and vestibulocochlear nerves.