Determination of wrist kinematics using a magnetic tracking device

The objective of this work is to present a method to determine the three-dimensional kinematics of the human wrist joint under physiological loading conditions using a magnetic tracking device. Euler angles were used to determine wrist extension-flexion, radial-ulnar deviation and supination-pronation. The screw displacement axis (SDA) method was used to describe the relative motion between carpal bones. Computer graphics were also used to obtain a better visualization of the three-dimensional motions of the carpal bones. This was accomplished by combining motion data and digitization data describing the geometry of the articular surfaces of the carpal bones. Geometric data included the locations of several points located on the articular surfaces forming the radio-scaphoid and radio-lunate joints. The SDA axes describing the motions of the capitate or the lunate or the scaphoid with respect to the radius during flexion-extension were found almost parallel to the medial-lateral direction. Translations along any SDA did not exceed 2 mm. One can thus consider the motion of each carpal bone as a pure rotation about a screw axis. Also, the SDA axis describing the motion of the capitate with respect to the radius was found to pass through the proximal end of the capitate. The graphical display of carpal motions shows that, as the wrist is flexed, the surface of the lunate within the radio-lunate articulation moves from palmar to dorsal. On the other hand, the palmar-dorsal location of the proximal surface of the scaphoid within the radio-scaphoid articulation remains almost unchanged.

[Studies on natural foci of tsutsugamushi disease of the autumn-winter type in Jiangsu]

Before 1986, tsutsugamushi disease was known only prevalent in south to Zhejiang Province in our country, belonged to the summer type and Leptotrombidium (L.) deliense was regarded as the main vector. In October 1986, the authors found this disease in Nanjing and carried out a series of studies in 1986-1992. The results were as follows: Tsutsugamushi disease was epidemic in Nanjing and north of Jiangsu (including: Dongtai, Haian, Rudong, Jinhu, Hanjiang, Jiangdu); belonged to the autumn-winter type; the main reservoir hosts were Apodemus agrarius, Rattus confucianus, R. norvegicus and Crocidura lasiura; the transmitting vector was L. (L.) scutellare; the pathogen of tsutsugamushi disease of the autumn-winter type-Rickettsia tsutsugamushi belonged to low-virulent strain, and could not easily be detected; after the inoculated mice were treated with diluted cyclophosphamide solution, 14 strains of R. tsutsugamushi have been isolated from rats, mites and patients; serological typing of their sera showed that they belonged to the Gilliam type; natural foci in Jiangsu could be divided into two types--flat land and hilly land.

Prenatal exposure to methadone delays the development of striatal cholinergic neurons

The effect of prenatal exposure to methadone via maternal osmotic minipumps on the expression of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) has been studied by light microscopy in the striatum of male and female rats. At postnatal day 10, rats of both sexes exhibit reduced intensity of ChAT-immunoreactive staining in striatal neurons in the methadone-treated group in comparison to either untreated or water-treated controls. Although the number and distribution of ChAT-immunoreactive neurons appear to be similar across all three groups, the size (cross-sectional area) of these neurons is significantly smaller in the methadone-treated animals. By postnatal day 22, there are no differences in the ChAT immunoreactivity of striatal neurons between the water-treated and methadone-treated animals. The size of these neurons in female animals of both treatment groups is significantly larger than those of male animals in the same groups at postnatal day 22. AChE histochemical staining is qualitatively similar between treatment groups in both age groups. Thus, prenatal exposure to methadone appears to produce a delay in the expression of ChAT in striatal neurons. It remains to be demonstrated whether these differences are a direct effect of methadone exposure or are a consequence of neonatal withdrawal.

Therapeutic tumor-specific cell cycle block induced by methionine starvation in vivo

The ability to induce a specific cell cycle block selectively in the tumor could have many uses in chemotherapy. In the present study we have achieved this goal of inducing a tumor-specific cell cycle block in vivo by depriving Yoshida sarcoma-bearing nude mice of dietary methionine. Further, we demonstrate that methionine depletion also causes the tumor to eventually regress. The antitumor effect of methionine depletion resulted in the extended survival of the tumor-bearing mice. The mice on the methionine-deprived diets maintained their body weight for the time period studied, indicating that tumor regression was not a function of body weight loss. The data reported here support future experiments utilizing methionine depletion as a target for tumor-selective cell cycle-dependent therapy.

Mechanism of DmS-II-mediated pause suppression by Drosophila RNA polymerase II

Transcription elongation factor S-II mediates nascent transcript cleavage by RNA polymerase II (Reines, D. (1992) J. Biol. Chem. 267, 3795-3800). We have examined the mechanism of action of the Drosophila S-II analog, DmS-II, in a defined transcription system. Our results show that DmS-II is necessary and sufficient to activate nascent transcript cleavage by RNA polymerase II during transcription of a dC-tailed template. The pattern of transcripts resulting from prolonged action by DmS-II indicates that there are kinetic barriers to transcript shortening. During the cleavage reaction, the polymerase remains in register with the template strand and generates mainly nucleotide dimers. The ability of DmS-II to mediate transcript shortening resides in the carboxyl-terminal half of the protein. Our results support a model for pause suppression in which DmS-II binds to the paused polymerase, causes one cleavage event and is then released from the complex. Elongation by the polymerase then allows a second encounter with the pause site and a second chance of passing the site. Complete pause suppression may require multiple transcript shortening events for some polymerase molecules.

Phosphorylation and activation of protamine kinase by two forms of a myelin basic protein kinase from extracts of bovine kidney cortex

Two myelin basic protein kinases designated MBPK-1 and MBPK-2 were purified to apparent homogeneity from extracts of bovine kidney cortex. The purified preparations exhibited an apparent M(r) approximately 40,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and approximately 42,000 (MBPK-1) and 45,000 (MBPK-2) by gel permeation chromatography. Up to 0.4 and 1.8 mol of phosphoryl groups were incorporated per mol of MBPK-1 and MBPK-2, respectively, on threonines following incubation with ATP. Autophosphorylation, incubation with protein phosphatase 2A2 (PP2A2), CD45, or T-cell protein tyrosine phosphatase did not affect MBPK-1 activity. Autophosphorylation increased by about 3-fold MBPK-2 activity. This autophosphorylation and activation was reversed by PP2A2 but not by CD45 or T-cell protein tyrosine phosphatase. MBPK-1 and MBPK-2 displayed a positive reaction with an antibody to mitogen-activated protein kinase. Purified preparations of protamine kinase were activated by about 1.5-6-fold and, after inactivation with PP2A2, were reactivated by about 30% by MBPK-1 and MBPK-2. Activation and reactivation correlated with the incorporation, respectively, of 0.1-0.5 and 0.5 mol of phosphoryl groups/mol of the protamine kinase on serines. The results show that MBPK-1 and MBPK-2 are protamine kinase-activating kinases and suggest that MBPK-1 and MBPK-2 may be related to mitogen-activated protein kinase.

Purification and characterization of an autophosphorylation-activated protein serine threonine kinase that phosphorylates and inactivates protein phosphatase 2A

Protein phosphatase 2A2 is inactivated by phosphorylation following incubation with purified preparations of an autophosphorylation-activated protein kinase (Hong Guo and Zahi Damuni (1992) Proc. Natl. Acad. Sci. U.S.A. 90, 2500-2504). This protein kinase was purified about 250,000-fold from extracts of bovine kidney to apparent homogeneity. The purified preparations exhibited a single polypeptide of apparent M(r) approximately 36,000. Up to 1 mol of phosphoryl groups was incorporated per mol of the purified kinase following incubation with ATP. This autophosphorylation reaction (t1/2 approximately 0.5-1 min) was accompanied by a approximately 10-fold activation of the kinase. Autophosphorylation and activation were reversed by protein phosphatase 2A2 or the catalytic subunit of protein phosphatase 1. Phosphoamino acid analysis indicated that the kinase underwent autophosphorylation on threonines. The rate of autophosphorylation was independent of the concentration of the enzyme and a slope of 0.97 (gamma = 0.998) was obtained by van't Hoff's plot indicating that autoposphorylation was intramolecular. Relative to myelin basic protein, the enzyme exhibited about 8, 62, 130, 33, 5, and < 0.1% activity with histones H1, H2A, H2B, H3, and H4 and with glycogen synthase alpha, respectively. Heparin inhibited the activity of the enzyme half-maximally at about 20 micrograms/ml. The results indicate that this autophosphorylation-activated kinase is a new protein kinase.

Hypothermia blunts acetylcholine increase in CSF of traumatically brain injured rats

Activation of muscarinic acetylcholine (ACh) receptors contributes to the pathophysiological consequences of moderate experimental traumatic brain injury (TBI). Hypothermia (30 degrees C) provides protection in experimental TBI. We measured ACh levels in CSF and plasma 5 min after moderate fluid percussion TBI under normothermic or hypothermic conditions, because ACh in the CSF has been correlated with the severity of behavioral deficits after TBI. Three groups were examined: TBI with hypothermic brain (30 degrees C), TBI with normothermic brain (37 degrees C), or sham TBI with normothermic brain (37 degrees C). ACh concentrations in CSF were significantly higher in 37 degrees C TBI rats, but not in 30 degrees C TBI rats compared to shams. ACh concentrations in plasma did not differ between groups. These results suggest that a contributing factor to the neuroprotective effects of moderate hypothermia in TBI may be related to the reduction of excessive ACh levels in the central nervous system following injury.

Autophosphorylation-activated protein kinase phosphorylates and inactivates protein phosphatase 2A

Purified preparations of a distinct autophosphorylation-activated protein kinase from bovine kidney phosphorylated and inactivated purified preparations of protein phosphatase 2A2 (PP2A2) by about 80% with the autophosphorylation-activated protein kinase, protamine kinase, and 32P-labeled myelin basic protein as substrates. Analysis of incubations performed in the presence of 0.2 mM [gamma-32P]ATP by autoradiography following SDS/PAGE and by FPLC gel permeation chromatography on Superose 12 demonstrated that the catalytic subunit of PP2A2 was phosphorylated in the incubation mixtures containing the kinase and phosphatase. Up to 0.3 mol of phosphate groups was incorporated per mol of the catalytic subunit of PP2A2 following incubation with the kinase. This phosphorylation was enhanced about 5-fold in the presence of 0.4 microM microcystin-LR. In addition, up to 1 mol of phosphate groups was incorporated per mol of the PP2A2 subunit of apparent M(r) approximately 60,000 when microcystin-LR was included. Analysis by thin-layer chromatography indicated that PP2A2 catalyzed an autodephosphorylation reaction which was inhibited by microcystin-LR. Phospho amino acid analysis showed that the catalytic subunit of PP2A2 was phosphorylated on threonine residues by the autophosphorylation-activated protein kinase. Together with previous observations, the results suggest that inactivation of PP2A by phosphorylation catalyzed by the autophosphorylation-activated protein kinase could contribute to the marked increase in the phosphorylation of cellular proteins in response to insulin and other mitogens.

Effect of catecholamines on intracellular pH in sheep cardiac Purkinje fibres

1. It has been reported that catecholamines affect intracellular pH (pHi) in a number of tissues, generally by altering the kinetics of the Na(+)-H+ exchanger. We postulated that catecholamines might affect pHi in cardiac tissue. We tested this in resting sheep cardiac Purkinje fibres by measuring transmembrane potential and pHi with standard and H(+)-sensitive microelectrodes. 2. Adrenaline and the beta-adrenergic agonist isoprenaline, both 5.0 x 10(-6) M, resulted in depolarization and intracellular acidification (adrenaline, 0.03 +/- 0.01 pH units, n = 8, P = 0.005; isoprenaline, 0.08 +/- 0.01 pH units, n = 17, P = 0.0001). The alpha-adrenergic agonist phenylephrine, at concentrations up to 200 microM, had no significant effect on membrane potential or pHi. 3. Isoprenaline significantly attenuated the half-time (t0.5) for pHi recovery from intracellular acidification induced via the NH4Cl pulse technique. Isoprenaline also attenuated the hyperpolarization that is normally seen at the onset of pHi recovery. Phenylephrine slightly reduced the t0.5 for recovery, although the reduction did not reach statistical significance. 4. Forskolin, 7.5-10 x 10(-5) M, an agent that raises intracellular cyclic adenosine 3',5'-monophosphate (cyclic AMP), also induced depolarization and acidification, similar to that induced by adrenaline and isoprenaline. 5. In the presence of the Na(+)-H+ exchange blocker 5-dimethyl amiloride, 2-6 x 10(-5) M, isoprenaline-induced acidification was blunted but not abolished. When administered in Na(+)-free Tyrode solution, isoprenaline-induced acidification was also not abolished. Buffering power, tested using the NH4Cl method, was not decreased by isoprenaline, but rather, was slightly increased. Reversal of H+ driving force across the cell membrane from the normally inward direction to outward (achieved by increasing pHo to 8.3-8.5 and depolarizing the membrane with 10 mM K+ solutions) did not prevent intracellular acidification from occurring in the presence of isoprenaline. When glycolysis was inhibited by a 60 min exposure to glucose-free solution containing 5.5 mM 2-deoxyglucose, acidification by isoprenaline was nearly abolished. 6. We conclude that, in resting sheep Purkinje fibres, beta- but not alpha-adrenergic stimulation results in intracellular acidification and depolarization, probably mediated via an increase in cyclic AMP. beta- but not alpha-adrenergic stimulation slows the rate of recovery from intracellular acidification and blunts the hyperpolarization associated with this recovery. 7. The intracellular acidification appears to be due both to partial inhibition of Na(+)-H+ exchange and to stimulation of glycolysis by beta-adrenergic agents.

[Application of electron microscopy in the diagnosis of neoplasms]

The majority of neoplasms can be diagnosed by light microscopy, but in some cases the diagnosis remains ambiguous due to poor differentiation, even though special stainings have been employed. This paper presents 34 cases of neoplasms in which the tumors were diagnosed by electron microscopy. This includes distinguishing (1) anaplastic carcinoma from lymphoma; (2) anaplastic carcinoma from amelanotic melanoma; (3) APUDoma from other tumors; (4) different mesenchymal tumors. The diagnoses of 4 cases of malignant melanoma, 11 cases of APUDoma, 7 cases of poorly differentiated carcinoma or anaplastic carcinoma, 2 cases of non-Hodgkin's lymphoma, 9 cases of mesenchymal tumors and 1 cases of other tumors have been resolved by electron microscopy. It is obvious that in some cases, electron microscopy can be of help in establishing a correct diagnosis.

Gap-junctional protein connexin 43 is expressed in dermis and epidermis of human skin: differential modulation by retinoids

Retinoids are effective modulators of proliferation and differentiation of keratinocytes in vivo and in vitro. In mouse 10T1/2 cells, retinoid action on proliferation and neoplastic transformation is correlated with the upregulation of gap-junctional communication and expression of connexin 43 (Cx43). In the present study we have determined if retinoids induce similar effects on gene expression in human skin. Studies were conducted in intact skin and on cultured keratinocytes and dermal fibroblasts. In a clinical study, 2 weeks of treatment with 0.05% all-trans retinoic acid resulted in increased expression of Cx43 mRNA and protein in epidermis. Expression occurred predominantly in the suprabasal layer. Cultured cells exhibited a differential response to retinoic acid. In keratinocytes, increased expression of Cx43 occurred at low (10(-11) M) concentrations, whereas inhibition occurred at high (10(-7) M) concentrations; however, junctional communication, measured by dye transfer, was not altered over this concentration range. Dermal fibroblasts, in contrast, exhibited a dose-dependent increased expression of Cx43 at concentrations up to 10(-7) M retinoic acid and proportionately increased their junctional communication over this dose range. These data indicate that control of Cx43 gene expression by retinoids in human skin cells is complex. The production of gradients of junctional channels could play a role in the control of growth and differentiation in epidermis.