A dynamic study of the ankle-foot complex

A kinematic study of the ankle-foot complex in 19 healthy volunteers was performed using computerized radiocinematography. We found that the instant centers of rotation of the ankle joint fell closely within the talus in the sagittal plane. When the ankle joint moved, the talus, the calcaneus and the navicular bone performed different excursions. Except for the movement in the sagittal plane, the calcaneus assumed eversion in dorsiflexion and inversion in plantar flexion when the ankle moved in an open kinematic chain (under non-weight-bearing conditions). In a closed kinetic chain movement (under weight-bearing conditions), the lower leg exhibited internal rotation, and the talus moved plantarward when the ankle was dorsiflexed. The internal rotation of the lower leg did not cause a slippery rotation of the foot on the surface, but rather it was converted into eversion of the calcaneus in the frontal plane.

Antibacterials. synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 4. Multiply-substituted aryl derivatives

The synthesis and structure-activity relationship (SAR) studies of the effect of different polysubstitution patterns in the aromatic ring of 5-(acetamidomethyl)oxazolidinone antibacterials (I) on antibacterial activity are presented. Compounds I were prepared by the six-step synthesis described previously (Gregory, W. A.; et al. J. Med. Chem. [formula: see text] 1989, 32, 1673), electrophilic aromatic substitution reactions of 3-substituted compounds, and functional-group interchange reactions of 3,4-disubstituted compounds. Antibacterial evaluation of compounds I against Staphylococcus aureus and Enterococcus faecalis gave the following results. The 2,4- and 2,5-disubstituted derivatives have weak or no antibacterial activity. Antibacterial activities of 3,4-disubstituted compounds are comparable to those of the 4-monosubstituted analogues for small 3-substituents (smaller than Br), but decline rapidly for larger 3-substituents. 3,4-Annulated derivatives are comparable in activity to their open-chain analogues. 3,5-Disubstituted and 3,4,5- and 2,4,6-trisubstituted derivatives are devoid of antibacterial activity.

[Exudative retinal detachment in the pregnancy-induced hypertension syndrome]

22 cases of pregnancy-induced hypertension syndrome with exudative retinal detachment were studied. Fluorescein angiography performed in 5 patients 7-14 days post-parturition revealed choroidal circulatory disturbances and retinal pigment epithelial damages, while the retinal capillaries also showed damages of varying degrees. The authors regarded the former as the primary pathological basis for the retinal detachment, with the latter also playing a pathogenic role. The incidence and the source of fluid of the retinal detachment in relation to general edema, proteinuria, and hypertension were discussed.

A calmodulin-binding peptide of caldesmon

Caldesmon is a major actin-binding protein identified in smooth muscle and many non-muscle cells. It also interacts with calmodulin and a number of other acidic proteins. We have shown previously that the polypeptide stretch from Val629 to Ser666 near the C terminus contains a calmodulin binding site (Wang, C.-L. A., Wang, L.-W. C., Xu, S., Lu, R. C., Saavedra-Alanis, V., and Bryan, J. (1991) J. Biol. Chem. 266, 9166-9172). On the other hand, Bartegi et al. (Bartegi, A., Fattoum, A., Derancourt, J., and Kassab, R. (1990) J. Biol. Chem. 265, 15231-15238) reported a cyanogen bromide fragment beginning at Trp659 which is also capable of binding both calmodulin and actin. A comparison of the overlapping sequence between these two peptides suggests that this calmodulin binding site is localized in a 7-residue segment, 659Trp-Glu-Lys-Gly-Asn-Val-Phe665. We have chemically synthesized an 18-residue peptide (GS17C, from Gly651 to Ser667 with an added cysteine at the C terminus) that contains this segment. This peptide was purified by high performance liquid chromatography and labeled with fluorescent probes at the terminal cysteine residue. We found that GS17C indeed binds calmodulin in a Ca(2+)-dependent manner (Kd = 8 x 10(-7) M) and appears to compete with caldesmon. Interestingly, this synthetic peptide also co-sediments with F-actin, binding to actin being displaceable by calmodulin, as in the case of the native caldesmon. But GS17C does not have any effect on the actomyosin ATPase activity, indicating that this peptide segment does not contain the inhibitory region.

Evaluation of 110 consecutive patients with dementias: a prospective study

We prospectively investigated 131 consecutive cases (both in- and outpatients) of suspected dementia to evaluate the relative frequency of different types of dementia in Chinese patients. Dementia was confirmed in 110 cases (84.0%). In contrast to the Western series, vascular dementia (39.1%) was slightly more frequent than the Alzheimer's disease (36.4%). Twelve cases (10.9%) of potentially treatable dementia were found. Careful clinical observation was the most useful part of the evaluation. CT scan of brain was the most useful laboratory test.

A long helix from the central region of smooth muscle caldesmon

The central region of smooth muscle caldesmon is predicted to form alpha-helices on the basis of its primary structure. We have isolated a fragment (CT54) that contains this region. The hydrodynamic properties and the electron microscopic images suggest that CT54 is an elongated (35 nm), monomeric molecule. The circular dichroic spectrum yields an overall alpha-helical content of 55-58%. These results are consistent with the model that the middle portion of CT54 forms a long stretch of single-stranded alpha-helix. Such a structure, if it in fact exists, is thought to be stabilized by numerous salt bridges between charged residues at positions i and i + 4. The structural characteristics of this fragment not only represent an unusual protein configuration but also provide information about the functional role of caldesmon in smooth muscle contraction.

Localization of the calmodulin- and the actin-binding sites of caldesmon

Expression of the C-terminal third of chicken gizzard caldesmon in Escherichia coli, using the Nagai vector (Nagai, K., and Thøgersen, H.V. (1987) Methods Enzmol. 153, 461-481), produces a cII-caldesmon fusion protein (27 kDa) with caldesmon sequence beginning at Lys579. Degradation during purification yields five peptides with molecular masses of 24, 22, 19 (two peptides), and 15 kDa. The 24-kDa peptide begins at Phe581; the 22-kDa peptide begins at Leu597, the two 19-kDa peptides begin at Phe581 and Val629, respectively; the 15-kDa peptide also begins at Val629. We estimate that the 15-kDa and one of the 19-kDa peptides end near Leu710. Site-directed mutagenesis was used to produce truncated peptides with known C termini; one peptide (17 kDa) terminates at Asn675. Digestion of the fragments with chymotrypsin generates a second 15-kDa fragment that begins at Ser666 (15K'). All of the peptides, with the exception of 15K', bind Ca(2+)-calmodulin-Sepharose and share a common 37-amino acid peptide between Val629 and Ser666, suggesting this contains the calmodulin binding site. Comparison with published sequences (Takagi, T., Yazawa, M., Ueno, T., Suzuki, S., and Yagi, K. (1989) J. Biochem. (Tokyo) 106, 778-783 and Bartegi, A., Fattoum, A., Derancourt, J., and Kassab, R. (1990) J. Biol. Chem. 265, 15231-15238) for other calmodulin-binding fragments further restricts the binding site to 7 residues, Trp-Glu-Lys-Gly-Asn-Val-Phe, between Trp659 and Ser666. All of the fragments, except the two 15-kDa peptides, co-sediment with F-actin, indicating that there are two segments in the C-terminal third of caldesmon that can interact with F-actin: one between Leu597 and Val629, the other between Arg711 and Pro756. Although separated in the primary sequence, these domains may interact with the calmodulin-binding region in the folded structure.

Ewing's sarcoma: metastatic tumor to the jaw

Metastatic tumors to the jaw are a rare occurrence. The incidence of metastatic Ewing's sarcoma to the jaw has been reported to be less than 2% of all cases of Ewing's sarcoma. Early detection of such lesions is difficult because the signs and symptoms do not appear until the lesion has progressed considerably. The treatment options are therefore limited to palliative care of the patient rather than cure. This article reports a case of Ewing's sarcoma that had metastasized to the mandible and reviews the literature.

Electron microscopic studies of chicken gizzard caldesmon and its complex with calmodulin

Caldesmon samples mounted on a stage rotating about a horizontal axis were shadowed keeping the shadow angle at about 3 degrees. This technique minimizes background metal deposits compared with the conventional method. The identity of caldesmon was confirmed by comparing the images of caldesmon alone with those of the caldesmon-calmodulin complex. In these samples the caldesmon molecules appeared to be elongated; most were between 30 and 80 nm in length. The maximum length was in good agreement with the earlier estimate of 74 nm based on hydrodynamic studies. Our observations also suggested the presence of a rather rigid 30-40 nm stretch in the middle of the caldesmon molecule, which was always visible under rotary shadowing, and a flexible structure of about 20 nm in length at each end of the molecule, which may or may not be visible depending on their orientation on the mica surface. In the samples of caldesmon crosslinked with calmodulin, we noticed the existence of complexes containing two calmodulin molecules per caldesmon molecule, separated by a distance of 60 nm, consistent with the suggestion that each end of caldesmon can interact with calmodulin.

[Evaluation of administrative practices for the registration of outpatients with pulmonary tuberculosis]

In this paper, the register state, regular therapy rate and sputum conversion rate for outpatients have been analysed. 30.5% of outpatients from other region were not registered. In these patients, regular therapy rate and sputum conversion rate were 10.9% and 53.7%, respectively. Comparing with above data, there were 97.3% and 96.8% for above 2 parameters in outpatients of Changhun region, 40.2% and 61.7% in outpatients of other region with register, under the management or control by hospital.

[Changes in parameters of hemorheology and circulation 6-keto-PGF1 alpha and TXB2 in dilated cardiomyopathy]

The changes in 12 parameters of hemorheology were observed and the levels of peripheral plasma 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2) measured in 35 cases of dilated cardiomyopathy (DCM), including 6 peripartum cardiomyopathy (PCM). We found that there is of hyperviscosity in DCM, the causes were decrease of erythrocyte deformability, increase of red blood cell aggregation, increase of plasma fibrinogen and TXA2 level and decrease of plasma 6-keto-PGF1 alpha level.

Four-year experience in the treatment of upper gastrointestinal strictures with balloon dilatation

One hundred and sixty-four cases of upper gastrointestinal tract stricture were treated by balloon dilatation in 4 years. A total of 682 procedures were performed. One hundred and forty cases (anastomosis stenosis 95, caustic stenosis 33 and other stenoses of the esophagus 12) were followed up with an effective rate of 90% (126/140) and a long-term effective rate of 71.4% (100/140). Fourteen cases (10%) failed, and 11 of them were due to tumor recurrence. The concept about the short-term and long-term effects, the criteria for evaluation of the results, the factors influencing the effectiveness, and the time suitable for dilatation are described. For the dilatation, indications are anastomosis stricture of the upper gastrointestinal tract, esophageal web and caustic stenosis of the esophagus. This method is also indicated for cicatricial stricture of the upper gastrointestinal tract of various causes.

[Clinical study and immunological observation on potenlini treatment of epidemic hemorrhage fever]

439 cases of epidemic hemorrhagic fever (EHF) in the febrile stage of the disease were randomly divided into two groups. 226 cases in therapeutic group were treated with daily intravenous drip of 60-100 ml potenlini for 3 days. Other measures of treatment in this group was just the same as those in the control group. The results showed that the duration of both the febrile stage and the hypotensive shock stage were shorter and the rate of recovering from hypotensive shock stage and oliguric stage in the therapeutic group (P less than 0.01) was higher as compared with the control group. BUN, ALT, urinary protein, white blood cells and platelets returned to normal level earlier than expected (P less than 0.01). The occurrence rate of complication and case fatality rate in therapeutic group were lower. The research showed that potenlini in the treatment of EHF has effects. But it has not remarkable effects on immune adjustment.

Antibacterials. Synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 2. The "A" group

The synthesis and structure-activity relationship (SAR) studies of the effect of varying the "A" group in a series of 5-(acetamidomethyl)oxazolidonone antibacterials (2) are described. Compounds 2 were principally prepared either by the six-step synthesis described previously (J. Med. Chem. 1989, 32, 1673) or by elaboration of the synthetic intermediate 2 (A = H) via electrophilic aromatic substitution or elaboration of the intermediate 2 (A = I) by transition metal catalyzed carbon-carbon bond-forming reactions. Antibacterial evaluation of compounds 2 with A = alkyl, ethenyl, ethynyl, hydroxyalkyl, aldo and keto, oximinoakyl, carboalkoxy, nitro, amino, halo and psi-halo, alkylthio, alkylsulfinyl, and alkysulfonyl against Staphylococcus aureus and Enterococcus faecalis led to the identification of several SAR trends. In several series of homologues (alkyl, ketyl, aximinoalkyl, amino, halo and psi-halo, and alkythio), antibacterial activity increased with increasing lipophilicity. But in series with where A is a substituent with a trior tetrasubstituted (substituent larger than H) quaternary atom attached directly to the aromatic ring (hydroxyalkyl, alkylsulfinyl, alkylsufonyl), the activity peaked at the member of the series with the "tert-butyl" connectivity pattern. Conjugated electron-withdrawing substituents also had increased activity relative to nonconjugated analogues of comparable lipophilicity.

Distance measurements in cardiac troponin C

Intramolecular distance measurements were made in cardiac troponin C (cTnC) by fluorescence energy transfer using Eu3+ or Tb3+ as energy donors and Nd3+ or an organic chromophore as acceptors. The laser-induced luminescence of bound Eu3+ is quenched in Eu1Nd1cTnC with a lifetime of 0.328 ms, compared with 0.43 ms for Eu2cTnC. The enhanced decay corresponds to an energy transfer efficiency of 0.25, or a distance of 1.1 nm between the two high affinity sites. We have also labeled cTnC with 4-dimethylaminophenylazophenyl-4'-maleimide (DAB-Mal) at the two cysteine residues (Cys-35 and Cys-84). Energy transfer measurements were carried out between Tb3+ bound to the high affinity sites and the labels attached to the domain containing the low affinity site. Upon uv irradiation at pH 6.7, Tb1cTnCDAB emits tyrosine-sensitized Tb3+ luminescence that decays bioexponentially with lifetimes of 1.29 and 0.76 ms. The shorter lifetime is ascribed to energy transfer from Tb3+ to the DAB labels, yielding an average distance of 3.4 nm between the donor and the acceptors. At pH 5.0, however, the luminescence decays exclusively with a single lifetime of 1.31 ms, suggesting that under these conditions all Tb3+ ions are more than 5.2 nm away from the label. Thus cTnC, like skeletal TnC, undergoes a pH-dependent conformational transition which converts an elongated structure at lower pH's to a rather compact conformation in a more physiological medium.

Antibacterials. Synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 1. The "B" group

The synthesis and structure/activity studies of the effect of varying the "B" group in a series of oxazolidinone antibacterials (I) are described. Two synthetic routes were used: (1) alkylation of aniline with glycidol followed by dialkyl carbonate heterocyclization to afford I (A = H, B = OH), whose arene ring was further elaborated by using electrophilic aromatic substitution methodology; (2) cycloaddition of substituted aryl isocyanates with epoxides to give A and B with a variety of values. I with B = OH or Br were converted to other "B" functionalities by using SN2 methodology. Antibacterial evaluation of compounds I with A = acetyl, isopropyl, methylthio, methylsulfinyl, methylsulfonyl, and sulfonamido and a variety of different "B" groups against Staphylococcus aureus and Enterococcus faecalis concluded that the compounds with B = aminoacyl, and particularly acetamido, were the most active of those examined in each A series, possessing MICs in the range of 0.5-4 micrograms/mL for the most active compounds described.

Caldesmon has two calmodulin-binding domains

Chicken gizzard caldesmon was cleaved with chymotrypsin or CNBr, and the calmodulin-binding fragments were isolated using an affinity column. Limited chymotryptic digestion gives rise to a 38 kDa calmodulin-binding fragment (CT40) as described previously (Szpacenko, A. & Dabrowska, R., FEBS Lett. 202, 182-186, 1986; Fujii, T., Imai, M., Rosenfeld, G. C. & Bryan, J., J. Biol. Chem. 261, 16155-16160, 1987; Yazawa, M., Yagi, K. & Sobue, K., J. Biochem. 102, 1065-1073, 1987). In the case of CNBr cleavage a 37 kDa calmodulin-binding fragment (CB40) was obtained. Both CT40 and CB40 contain a reactive thiol group, but these thiols are apparently in different environments as judged by the responses of attached fluorescent labels to calmodulin-binding. A comparison of the N-terminal sequences of CB40 and CT40 with the complete sequence of caldesmon shows that the two calmodulin-binding fragments in fact originate from different parts of the parent molecule. Thus there exist two calmodulin-binding sites in caldesmon, one in the N-terminal half and the other in the C-terminal half of the molecule. This is consistent with the recent finding that up to two calmodulin molecules can be crosslinked to each caldesmon molecule (Wang, C.-L.A., Biochem. Biophys. Res. Commun., 156, 1033-1038, 1988).

[Treatment of retinal neovascularization secondary to branch vein occlusion with argon laser photocoagulation]

20 cases (22 eyes) of retinal neovascularization (RNV) secondary to branch vein occlusion were treated with argon laser photocoagulation. The RNV and the area of nonperfusion in these eyes were detected by fluorescein angiography. The results showed that argon laser photo coagulation was a highly effective therapy for RNV which was refractory to treatment. Photocoagulation minimized or resolved RNV and prevented recurrent vitreous hemorrhage. The relationship of RNV with the area of nonperfusion, the selection of the direct or indirect modality, and the points of note for success and prevention of complications were discussed.

pH-dependent conformational changes of wheat germ calmodulin

Fluorescence energy transfer measurements were carried out between landmarks on wheat germ calmodulin to measure the interdomain distance. Tb3+ ions bound at the four Ca2+-binding sites were used as energy donors, and an organic chromophore, [4-(dimethylamino)-phenyl-4'-azophenyl]maleimide, attached to the single cysteine residue at position 27, was used as the acceptor. At pH's near neutrality all bound Tb3+ ions emit luminescence with shortened lifetimes as a result of energy transfer to the acceptor; at pH 5, however, part of the metal emission becomes unquenched. When the protein is subjected to limited digestion with trypsin in the presence of Ca2+, resulting in the formation of two fragments, each corresponding to half of the molecule, the decay of Tb3+ emission is no longer pH sensitive. These results suggest that, like rabbit skeletal troponin C [Wang, C.-L. A., Zhan, Q., Tao, T., & Gergely, J. (1987) J. Biol. Chem. 257, 8372-8375], wheat germ calmodulin exists in a relatively compact conformation at neutral pH's, but becomes more elongated at pH 5.

Ultrastructure and synaptic architecture of spinal motoneurons in the frog (Rana catesbeiana)

An electron-microscopic analysis of spinal motoneurons and their synapses was carried out in a frog (Rana catesbeiana). Six different types of boutons (S, F, M, P, C and GS) have been identified. Their distribution on spinal motoneuron somata and proximal dendrites is described. The mean linear percentage of the surface area covered by boutons is 26.1 +/- 1.9%. S-type boutons are preferentially concentrated on the soma and proximal dendrites. The relative number of S-type boutons (58.7%) was greater (p less than 0.01) than that of F-type boutons (41.3%). This is in contrast to mammalian spinal motoneurons where F-type boutons are much more numerous on the soma than S-type boutons. F-type boutons are randomly distributed and the average ratio of S:F-type boutons is 20:14 (S:F ratio = 1.4). In contrast, M-type boutons synapse exclusively on the distal part of the dorsal dendrites and are restricted to the intermediate zone or to the dorsal horn. P-type boutons form synapses upon the large M-type boutons. The polarity of these axoaxonic synapses is always from P to M. Similarities and differences between the synaptology of frog and mammalian spinal motoneurons are discussed.

Photocrosslinking of calmodulin and/or actin to chicken gizzard caldesmon

The two sulfhydryl groups of chicken gizzard caldesmon were specifically labeled with a photoreactive crosslinker, benzophenone-maleimide, to study its interactions with calmodulin and/or actin. When incubated with F-actin caldesmon crosslinks to a single actin monomer; it can, however, crosslink to up to two calmodulin molecules in the presence, but not in the absence, of Ca2+. Thus caldesmon may have two calmodulin-binding sites, each containing, or being near, one of the two thiol residues. One of these two sites may also be adjacent to the actin-binding site. A calmodulin-binding fragment of caldesmon resulting from cyanogen bromide digestion crosslinks to a single calmodulin molecule, also in a Ca2+-dependent manner. Crosslinking of calmodulin to caldesmon does not prevent the latter from binding F-actin, suggesting that calmodulin and actin do not compete with each other for the same binding site(s) on the caldesmon molecule.

Caldesmon. Molecular weight and subunit composition by analytical ultracentrifugation

A wide range of values has been reported for the subunit and molecular weights of smooth muscle caldesmon. There have also been conflicting reports concerning whether caldesmon is a monomer or dimer. We attempted to resolve these uncertainties by determining the molecular weight of chicken gizzard smooth muscle caldesmon using the technique of sedimentation equilibrium in the analytical ultracentrifuge. Unlike previous methods that have been used to estimate the molecular weight of caldesmon, the molecular weight determined by equilibrium sedimentation does not depend upon assumptions about the shape of the molecule. We concluded that caldesmon in solution is monomeric with a molecular mass of 93 +/- 4 kDa, a value that is much less than those previously reported in the literature. This new value, in conjunction with sedimentation velocity experiments, led to the conclusion that caldesmon is a highly asymmetric molecule with an apparent length of 740 A in solution. The mass of a cyanogen bromide fragment, with an apparent mass of 37 kDa from sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was determined to be 25.1 +/- 0.6 kDa using sedimentation equilibrium. These results imply that the reported molecular weights of other fragment(s) of caldesmon have also been overestimated. We have determined an optical extinction coefficient for caldesmon (E1%(280 nm) = 3.3) by determining its concentration from its refractive index which was measured in the analytical ultracentrifuge. From the above values of the molecular weight and the extinction coefficient, we redetermined that the caldesmon molecule has two cysteines and recalculated the stoichiometric molar ratio of actin/tropomyosin/caldesmon in the smooth muscle thin filament to be 28:4:1.

pH-dependent structural transition in rabbit skeletal troponin C

Although the crystal structure of troponin C is known (Herzberg, O., and James, M. N. G. (1985) Nature 313, 653-659; Sundaralingam, M., Bergstrom, R., Strasburg, G., Rao, S. T., Roychowdhury, P., Greaser, M., and Wang, B. C. (1985) Science 227, 945-948), its structure in solution, particularly under physiological conditions, has not been established. We examined the conformation of troponin C under a variety of conditions by measuring the distance between sites located in the N- and C-terminal domains using the technique of resonance energy transfer. The donor was the luminescent lanthanide ion Tb3+ bound at the low affinity metal sites in the N-terminal domain. The acceptor was 4-dimethylaminophenylazophenyl-4'-maleimide attached at Cys-98 in the C-terminal domain. The distance between these sites was found to be greater than 5.2 nm at pH 5.0, 2.7 nm at pH 6.8 for uncomplexed troponin C, and 4.1 nm for troponin C complexed with troponin I at pH 6.8. These findings suggest that uncomplexed troponin C undergoes a pH-dependent transition from an elongated conformation, compatible with the crystal structure at acidic pH, to a more compact conformation at neutral pH. When complexed with troponin I, troponin C adopts a conformation of intermediate length compared to the uncomplexed molecule at pH 6.8 and 5.0.

Influence of microgravity on cellular differentiation in root caps of Zea mays

We launched imbibed seeds of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on cellular differentiation in root caps. The influence of microgravity varied with different stages of cellular differentiation. Overall, microgravity tended to 1) increase relative volumes of hyaloplasm and lipid bodies, 2) decrease the relative volumes of plastids, mitochondria, dictyosomes, and the vacuome, and 3) exert no influence on the relative volume of nuclei in cells comprising the root cap. The reduced allocation of dictyosomal volume in peripheral cells of flight-grown seedlings correlated positively with their secretion of significantly less mucilage than peripheral cells of Earth-grown seedlings. These results indicate that 1) microgravity alters the patterns of cellular differentiation and structures of all cell types comprising the root cap, and 2) the influence of microgravity on cellular differentiation in root caps of Zea mays is organelle specific.

Projection pattern of vestibulocerebellar fibers in the anterior vermis of the cat: an anterograde wheat germ agglutinin-horseradish peroxidase study

The distribution of mossy fiber terminals of vestibulocerebellar fibers was studied in the anterior lobe following a unilateral injection of wheat germ agglutinin-horseradish peroxidase into the medial and descending vestibular nuclei in the cat. In the transverse plane 3 groups of labeled terminals were seen bilaterally: group 1 located in the midline region, group 2 at 0.5 mm, and group 3 between 0.75 and 1.5 mm lateral to the midline. Reconstruction of the distribution in the horizontal plane revealed that the labeled terminals were distributed in 3 areas extending apicobasally in the basal part of the lobules.

Influence of microgravity on root-cap regeneration and the structure of columella cells in Zea mays

We launched imbibed seeds and seedlings of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on 1) root-cap regeneration, and 2) the distribution of amyloplasts and endoplasmic reticulum (ER) in the putative statocytes (i.e., columella cells) of roots. Decapped roots grown on Earth completely regenerated their caps within 4.8 days after decapping, while those grown in microgravity did not regenerate caps. In Earth-grown seedlings, the ER was localized primarily along the periphery of columella cells, and amyloplasts sedimented in response to gravity to the lower sides of the cells. Seeds germinated on Earth and subsequently launched into outer space had a distribution of ER in columella cells similar to that of Earth-grown controls, but amyloplasts were distributed throughout the cells. Seeds germinated in outer space were characterized by the presence of spherical and ellipsoidal masses of ER and randomly distributed amyloplasts in their columella cells. These results indicate that 1) gravity is necessary for regeneration of the root cap, 2) columella cells can maintain their characteristic distribution of ER in microgravity only if they are exposed previously to gravity, and 3) gravity is necessary to distribute the ER in columella cells of this cultivar of Z. mays.

Distance measurements between metal-binding sites of calmodulin and from these sites to Cys-133 of troponin I in the binary complex

Distances between the four Ca2+-binding sites of calmodulin (CaM) have been measured by fluorescence energy transfer techniques using Eu3+ and Tb3+ as energy donors and a number of other lanthanide ions (Ln3+) as acceptors. It was shown previously that lanthanide ions preferentially bind to sites I and II of CaM with an affinity higher than that for sites III and IV (Kilhoffer, M.-C., Demaille, J. G., and Gerald, D. (1980) FEBS Lett. 116, 269-272; Wang, C.-L. A., Aquaron, R. R., Leavis, P. C., and Gergely, J. (1982) Eur. J. Biochem. 124, 7-12). Thus upon direct excitation with a laser the luminescence lifetimes of Eu1Ln1CaM and Tb1Ln1CaM provide information on the distance between sites I and II. On the other hand, since Tb3+ ions bound to sites III and IV are sensitizable through tyrosine residues, lifetime measurements of Tb2Ln2CaM excited by UV light yield the distance between sites III and IV. Both pairs of sites were found to be separated by a distance of 1.05 +/- 0.07 nm. Binding of Ca2+ to sites III and IV does not alter the distance between sites I and II. We have also attached a chromophoric label, dimethylaminophenylazobenzene, to Cys-133 of skeletal troponin I and carried out distance measurements on its complex with CaM by both direct and indirect excitation. The averaged distances from sites I and II in the N-terminal half and from sites III and IV in the C-terminal half of the CaM molecule to the label on troponin I are 2.7 and 2.5 nm, respectively.

Cerebellar corticovestibular projections from lobule IX to the descending vestibular nucleus in the cat. A retrograde wheat germ agglutinin-horseradish peroxidase study

The distribution of Purkinje cells projecting to the descending vestibular nucleus was studied in lobule IX (uvula) of the cat by the retrograde wheat germ agglutinin-horseradish peroxidase method. In the transverse plane labeled Purkinje cells were seen diffusely within 1.0 mm from the midline and densely for 250-500 microns at around 1.0 mm lateral to the midline. Reconstruction of the distribution in the horizontal plane revealed that they were distributed in longitudinal areas extending in the apicobasal extent of lobule IX.

[Intracytoplasmic desmosome in squamous cancer cells of the lung in man]

Ultrastructure of intracytoplasmic (cytoplasmic) desmosomes in the squamous cancer cells of the human lung was studied by electron microscopy. In 17 cases of non-keratosic squamous cell carcinoma of the lung, intracytoplasmic (cytoplasmic) desmosomes were found in 4. In contrast to what previous investigators had proposed that the intracytoplasmic desmosomes are formed by cell fusion with the membrane being deep in the cell and cell digestion under the diffusion of hydrolytic enzymes, our result indicates that the intracytoplasmic desmosomes might be a structure formed by cell intima system itself during cell division. The structure suggests that the desmosomes originate from the cell intima system.

Modulation of the interaction between the two halves of troponin C by the other troponin subunits

The interactions between troponin subunits have been studied by intrinsic fluorescence and electron spin resonance (ESR) spectroscopy. The tryptophan fluorescence of troponin T (TnT) and troponin I (TnI) when complexed with troponin C (TnC) undergoes a Ca2+-dependent transition. The midpoints of such spectral changes occur at pCa approximately equal to 6, suggesting that the conformational change of TnT and TnI is induced by Ca2+ binding to the low-affinity sites of TnC. When TnC is labelled at Cys-98 with a maleimide spin probe (MSL), the spin signal is sensitive to Ca2+ binding to both the high and the low-affinity sites of TnC in the presence of either or both of the other two troponin subunits. Since Cys-98 is located in the vicinity of one of the high-affinity sites, these results are indicative of a long-range interaction between the two halves of the TnC molecule. Our earlier kinetic studies [Wang, C.-L. A., Leavis, P. C. & Gergely, J. (1983) J. Biol. Chem. 258, 9175-9177] have shown such interactions in TnC alone. Since the ESR spectral change associated with metal binding to the low-affinity sites is only observed when MSL-TnC is complexed with TnT and/or TnI, this long-range interaction within TnC appears to be mediated through the other troponin subunits.

Construction of a Tn5 derivative determining resistance to gentamicin and spectinomycin using a fragment cloned from R1033

A physical and genetic map of the IncP plasmid R1033 was constructed: restriction fragments were subcloned and antibiotic resistance genes were located. The map is consistent with previous reports that R1033 is a derivative of RP4 carrying a 16-kb transposon Tn1696 which contains the antibiotic-resistance determinants present on R1033 but not on RP4. A BamHI fragment from R1033, determining resistance to gentamicin, spectinomycin and streptomycin, was cloned into Tn5, replacing the central Bg/II fragment that determined kanamycin resistance, producing a recombinant transposon Tn5-GmSpSm. This was shown to transpose in Rhizobium leguminosarum at a frequency similar to that of the parental Tn5.

The influence of gravity on the formation of amyloplasts in columella cells of Zea mays L

Columella (i.e., putative graviperceptive) cells of Zea mays seedlings grown in the microgravity of outer space allocate significantly less volume to putative statoliths (amyloplasts) than do columella cells of Earth-grown seedlings. Amyloplasts of flight-grown seedlings are significantly smaller than those of ground controls, as is the average volume of individual starch grains. Similarly, the relative volume of starch in amyloplasts in columella cells of flight-grown seedlings is significantly less than that of Earth-grown seedlings. Microgravity does not significantly alter the volume of columella cells, the average number of amyloplasts per columella cell, or the number of starch grains per amyloplast. These results are discussed relative to the influence of gravity on cellular and organellar structure.