Do arm postures vary with the speed of reaching?

Do arm postures vary with the speed of reaching? For reaching movements in one plane, the hand has been observed to follow a similar path regardless of speed. Recent work on the control of more complex reaching movements raises the question of whether a similar "speed invariance" also holds for the additional degrees of freedom. Therefore we examined human arm movements involving initial and final hand locations distributed throughout the three-dimensional (3D) workspace of the arm. Despite this added complexity, arm kinematics (summarized by the spatial orientation of the "plane of the arm" and the 3D curvature of the hand path) changed very little for movements performed over a wide range of speeds. If the total force (dynamic + quasistatic) had been optimized by the control system (e.g., as in a minimization of the change in joint torques or the change in muscular forces), the optimal solution would change with speed; slow movements would reflect the minimal antigravity torques, whereas fast movements would be more strongly influenced by dynamic factors. The speed-invariant postures observed in this study are instead consistent with a hypothesized optimization of only the dynamic forces.     

Effects of muscle blood flow on muscle energy metabolism and contractility

Energy metabolism and contractility of rat’s femoral triceps muscles were investigated by varying blood flow levels with ligation of the femoral artery. The triceps were stimulated electrically to produce equivalent conditions as exercise loading, and phosphorus nuclear magnetic resonance (³¹P-NMR) spectra and muscle tension levels were monitored. The ratio of inorganic phosphate (Pi) to ‘Pi+phosphocreatine (PCr)’, i.e. Pi/(Pi+PCr), was obtained from ³¹P-NMR spectra. This ratio was related to the reduction of blood flow ratio (BFR) during and after the stimulation period, whereas before starting the stimulation, there was no significant correlation. These findings indicate: (i) muscle energy metabolism during decreased blood flow is influenced by the stimulation (loading) given to the muscle; and (ii) changes of muscle energy metabolism due to decreased muscle blood flow during the loading is evaluable by measuring ³¹P-NMR spectra. Muscle tension reached the plateau 8 min after starting the stimulation, regardless of BFR, but muscle tension ratio decreased as BFR became lower. This indicates that decreased blood flow diminishes muscle contractility, and then lowers muscle function levels. Our findings indicate that muscle blood flow plays an important role in muscle function, and blood flow and muscle function levels are evaluable by measuring ³¹P-NMR spectra of the muscle.     

Conversion of Salmonella typhimurium to L-forms contributes to the maintenance of acquired immunity against murine typhoid.

Conversion of Salmonella typhimurium to L-forms, both in vitro and in vivo, resulted in the expression of proteins cross-reacting to the mycobacterial 65,000 MW heat-shock protein (hsp). Immunization of C3H/HeJ mice with a protective dose of stable L-form S. typhimurium induced gamma delta T cells in the liver, in accordance with the multiplication of L-form Salmonella in Kupffer cells. The number of gamma delta T cells decreased after the intracellular growth of L-form Salmonella plateaued. Persistance of the L-forms in Kupffer cells, however, allowed hepatic gamma delta T cells to increase within 48 hr of infection with virulent S. typhimurium. Thus, the intrahepatic colonization of L-form Salmonella seems to keep gamma delta T cells on standby, but the emergence of these T cells does not correlate with the expression of L-form hsp. In addition, Kupffer cells colonized by L-forms constitutively synthesized mRNA for interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha). These results suggest that conversion of S. typhimurium to L-forms in phagocytic cells builds up and maintains acquired resistance, conferred by live-cell vaccines of S. typhimurium, against murine typhoid.     

Implication of the common {gamma} chain of the IL-7 receptor in intrathymic development of pro-T cells

The effects of IL-7 on the growth and differentiation of thymocyteswere analyzed using murine fetal thymua organ cultures (FTOC)in the presence of mAbs specific for the conventional IL-7 receptor(1L-7R) and for the common (c) chain. In FTOC, the developmentof CD4^–CD8^– double-negative thymocytes to CD4+CD8+double-positive (DP) and CD4+ or CD8+ single-positive (SP) cellswas not completely blocked by adding these mAbs, although cellgrowth was reduced by the treatment. To define a developingstage sensitive to the mAbs, most immature thymocytes, Pgp-1⁺c-kit cells, were cultured in the 2-deoxyguartosine treatedfetal thymus. In the presence of both mAbs in the culture, neitherDP nor SP thymocytes developed whereas either of the mAbs partiallyblocked their development. These results indicate that the Cchain is involved in early T cell development as an indispensablesubunlt of the functional IL-7 receptor complex.     

B cell development is perturbed in bone marrow from c-fos/v-jun doubly transgenic mice

c-fos and c-jun gene products form a heterodimeric complex (AP-1)that regulates target gene expression by binding to a specificDNA sequence motif. In order to study a role of AP-1 (Fos/Jun)in growth and differentiation of immature B lineage cells, wehave established and mated two independent transgenic mice carryingthe mouse c-fos gene or the viral v-Jun gene fused to the H-2Kpromoter. IL-7 dependent bone marrow cell culture from doublytransgenic (H2-fos/jun) mice demonstrated severe delay of earlyB cell development. Proliferation of pre-B cells in the freshbone marrow from HZ-fos/jun mice to IL-7 stimulation was verylow. These results suggest that the deregulated production ofAP-1 perturbs IL-7 mediated proliferation and differentiationof immature B cells.     

Influence of the anti-T4 autoantibody cross-reacting with T3 on serum T3 level determined by RIA

We encountered a patient who showed remarkably high binding capacities of both 125I-T4 and 125I-T3, which suggests the presence of antithyroid hormone autoantibody. However, the serum level of T3 in the patient was not abnormal. Study of the specificity of anti-thyroid autoantibody revealed that the antibody present in the patient was the anti T4 antibody, which cross-reacted with T3. In addition, the binding capacity of the T4 autoantibody with T3 was inhibited by T4. Endogenous T4 is always present when T3 is determined by radioimmunoassay. Our findings indicate that the normal T3 level in the patient was because endogenous T4 inhibited the autoantibody binding with T3.     

Adrenocortical carcinoma in infancy. Report of a case with immunohistochemical and ultrastructural studies

A case of adrenocortical carcinoma associated with congenital heart defect in a 6-month-old Japanese girl is reported. A fist-sized tumor was incidentally noted in the right hypochondrium upon admission for cardiac surgery. No clinical endocrinopathy was evident in this case. The resected tumor was encapsulated with smooth surface and no invasion to adjacent tissues or organs was observed. Histologically, the tumor was composed of small cells with granular or clear cytoplasm, and occasional giant cells with single or multiple nuclei. By electron microscopy, the tumor cells showed various nuclear contours with distinct nucleoli and had a moderate amount of cytoplasm containing abundant rough endoplasmic reticulum and mitochondria with variable-sized electron-dense granules. Intercellular desmosome-like junctions were observed in some tumor cells. Immunohistochemically, the tumor cells contained granules positive for estriol, progesterone and cortisol. These morphological findings including electron microscopic features suggested that the tumor cells had a malignant character.     

EXFOLIATIVE CYTOPATHOLOGY OF ALVEOLAR RHABDOMYOSARCOMA

Exfoliative cytopathology of alveolar rhabdomyosarcoma is presented. A 34-year-old male was found to have alveolar rhabdomyosarcoma of the retroperitoneum at autopsy. Ascites was recognized in the course of this disease. Cytological features in the ascites were characterized by relatively small-sized ovoid cells observed singly or in loose clusters. The neoplastic cells possessed small amount of rather vesicular cytoplasm and an eccentric nucleus. The nucleus characteristically revealed multiple deep indentations in the nuclear membrane, a few prominent eosinophilic nucleoli and finely granular or evenly distributed chromatin pattern. These cytological findings, especially the nuclear features, might be useful to differentiate alveolar rhabdomyosarcoma from other neoplasms which consist of relatively small-sized ovoid cells even if the striated muscle origin cannot be confirmed by immunoperoxidase staining.     

Effect of finite phosphor thickness on detective quantum efficiency

In this paper we describe theoretically the relationship between the finite thickness of a phosphor screen and its spatial-frequency-dependent detective quantum efficiency DQE(f-). The finite thickness of the screen causes a variation in both the total number of light quanta emitted from the screen in a burst from a given x-ray interaction and in the spatial distribution of the quanta within the light burst [i.e., shape or point spread function (PSF) of the light burst]. The variation in magnitude of the burst gives rise to a spatial-frequency-independent reduction in DQE, characterized by the scintillation efficiency As. The variation in PSF causes a roll off in DQE with increasing spatial frequency which we have characterized by the function Rc(f). Both As and Rc(f) can be determined from the moments of the distribution of the spatial Fourier spectrum of light bursts emitted from the phosphor and thus they are related: As is a scaling factor for Rc(f). Our theory predicts that it is necessary for all light bursts which appear at the output to have the same magnitude to maximize As and the same shape to maximize Rc(f). These requirements can lead to the result that the fluorescent screen with the highest modulation transfer function will not necessarily have the highest DQE(f) even at high spatial frequencies.     

Cloning of TPA-inducible early (TIE) genes by differential hybridization using TPA-Nonresponsive variant of mouse 3T3-L1 cells

The tumor promoter 12-O -tetradecanoylphorbol-13-acetate (TPA) induces DNA synthesis in quiescent 3T3-L1 cells but not in its variant VT-1 cells. A gt10 cDNA library was constructed using poly(A)⁺ RNA from 3T3-L1 cells that were stimulated by TPA for 20 min. Radioactive cDNA probes were prepared from mRNAs of TPA-treated 3 T3-L1 and VT-1 cells and used for screening of the 3T3-L1 cDNA library by differential hybridization. Nine of 6000 phage plaques hybridized only to the 3T3-L1 cDNA probe. Analysis of the nucleotide sequence of five of these clones indicated a high degree of homology with human or mouse type I and type III collagen genes. Three other independent clones showed no homology with any known DNA sequences. These isolated clones of TPA-inducible early (TIE) genes may be useful to study the signal transduction pathway of phorbol esters.