Pulse characteristics of an optical parametric oscillator pumped by sub-30-fs light pulses

We obtained nearly transform-limited light pulses of 34 fs near 1.2 microm by pumping an optical parametric oscillator with a 2-mm-long KTP crystal by 26-fs pulses from a Ti:sapphire laser. The average power of the pulses that were obtained was greater than 50 mW, at an 80-MHz repetition rate. Attempts to downscale the pulse duration by decreasing the pump-pulse duration revealed remarkable limitations of the attainable pulse length for sub-30-fs pump pulses, in accordance with a recent theoretical study [J. Opt. Soc. Am. B 17, 741 (2000)].

Molecular basis of ligand recognition by integrin alpha5beta 1. II. Specificity of arg-gly-Asp binding is determined by Trp157 OF THE alpha subunit

Different beta(1) integrins bind Arg-Gly-Asp (RGD) peptides with differing specificities, suggesting a role for residues in the alpha subunit in determining ligand specificity. Integrin alpha(5)beta(1) has been shown to bind with high affinity to peptides containing an Arg-Gly-Asp-Gly-Trp (RGDGW) sequence but with relatively low affinity to other RGD peptides. The residues within the ligand-binding pocket that determine this specificity are currently unknown. A cyclic peptide containing the RGDGW sequence was found to strongly perturb the binding of the anti-alpha(5) monoclonal antibody (mAb) 16 to alpha(5)beta(1). In contrast, RGD peptides lacking the tryptophan residue acted as weak inhibitors of mAb 16 binding. The epitope of mAb 16 has previously been localized to a region of the alpha(5) subunit that contains Ser(156)-Trp(157). Mutation of Trp(157) (but not of Ser(156) or surrounding residues) to alanine blocked recognition of mAb 16 and perturbed the high affinity binding of RGDGW-containing peptides to alpha(5)beta(1). The same mutation also abrogated recognition of the alpha(5)beta(1)-specific ligand peptide Arg-Arg-Glu-Thr-Ala-Trp-Ala (RRETAWA). Based on these findings, we propose that Trp(157) of alpha(5) participates in a hydrophobic interaction with the tryptophan residue in RGDGW, and that this interaction determines the specificity of alpha(5)beta(1) for RGDGW-containing peptides. Since the RGD sequence is recognized predominantly by amino acid residues on the beta(1) subunit, our results suggest that Trp(157) of alpha(5) must lie very close to these residues. Our findings therefore provide new insights into the structure of the ligand-binding pocket of alpha(5)beta(1).

Alpha 3 beta 1 adhesion to laminin-5 and invasin: critical and differential role of integrin residues clustered at the boundary between alpha 3 N-terminal repeats 2 and 3

Integrin/ligand interaction is a therapeutic target for many diseases. We previously reported that residues critical for ligand binding are clustered in N-terminal repeat 3 (in the predicted 2-3 loop) of alpha 4, alpha 5 and alpha IIb. Here we have localized residues critical for ligand binding in the alpha 3 subunit of integrin alpha 3 beta 1 with distinct ligand specificity (laminin-5). We identified an alpha 3 epitope common to several function-blocking anti-alpha 3 antibodies at the boundary between repeats 1 and 2 (residues 75-80). We found that swapping the predicted 4-1 loop (residues 153-165) at the boundary between repeats 2 and 3 with the corresponding alpha 4 sequence and mutating Thr-162 and Gly-163 residues in this predicted loop block laminin-5 binding. Thr-162 and Gly-163 and the antibody epitope are separated in the primary structure; however, they are close to each other in the proposed beta-propeller model. Mutating residues recently reported to block (Tyr-186 and Trp-188) or enhance (Asp-122) laminin-5 binding to alpha 3 beta 1 [Krukonis, E. S., Dersch, P., Eble, J. A., and Isberg, R. R.(1998) J. Biol. Chem. 273, 31837-31843] did not affect laminin-5 binding under the assay conditions used. Thr-162 and Gly-163 are not critical for adhesion to invasin, indicating that laminin-5 and invasin may use different recognition mechanisms, and that mutation of Thr-162 and Gly-163 does not drastically affect the integrity of alpha 3 beta 1. These results suggest that residues critical for ligand binding may be similarly (but not identically) located in repeat 3 of the alpha subunit regardless of ligand specificity.

Chemical cleavage of the overexpressed mitochondrial F1beta precursor with CNBr: a new strategy to construct an import-competent preprotein

We have isolated a soluble import-competent 15 kDa N-terminal fragment of the overexpressed Nicotiana plumbaginifolia F1beta precursor of the ATP synthase (N15pF1beta). The isolation was achieved after chemical cleavage, with CNBr, of the insoluble precursor collected in inclusion bodies, followed by purification of the fragment using ion-exchange chromatography. The purity of the final product was estimated to be more than 99%. N15pF1beta contained a presequence of 54 amino acid residues (except for the N-terminal methionine residue) and 82 N-terminal residues of the mature protein. N15pF1beta was shown to be imported into isolated potato tuber mitochondria and to be processed by the isolated mitochondrial processing peptidase (MPP) integrated into the cytochrome bc1 complex of the respiratory chain. Addition of N15pF1beta at micromolar concentrations resulted in the inhibition of import of F1beta precursor and alternative oxidase precursor, synthesized in vitro, into isolated mitochondria as well as the processing of these precursors catalysed by the isolated MPP-bc1 complex. N15pF1beta conjugated via a biotin link to avidin blocked import sites even after the reisolation of mitochondria and inhibited the import of the mitochondrial precursors, indicating that it can be used as a substrate for the generation of a stable translocation intermediate. Our results present a novel procedure for the production of an N-terminal fragment of the F1beta precursor that contains all information necessary for mitochondrial targeting and processing and that can be used for structural and functional studies of the mitochondrial protein import system. This procedure has a general value because it can be used for the production of chemical quantities of any mitochondrial import substrate and presequence peptide.

Specific binding of integrin alpha v beta 3 to the fibrinogen gamma and alpha E chain C-terminal domains

Integrin alpha v beta 3, a widely distributed fibrinogen receptor, recognizes the RGD572-574 motif in the alpha chain of human fibrinogen. However, this motif is not conserved in other species, nor is it required for alpha v beta 3-mediated fibrin clot retraction, suggesting that fibrinogen may have other alpha v beta 3 binding sites. Fibrinogen has conserved C-terminal domains in its alpha (E variant), beta, and gamma chains (designated alpha EC, beta C, and gamma C, respectively), but their function in cell adhesion is not known, except that alpha IIb beta 3, a platelet fibrinogen receptor, binds to the gamma C HHLGGAKQAGDV400-411 sequence. Here we used mammalian cells expressing recombinant alpha v beta 3 to show that recombinant alpha EC and gamma C domains expressed in bacteria specifically bind to alpha v beta 3. Interaction between alpha v beta 3 and gamma C or alpha EC is blocked by LM609, a function-blocking anti-alpha v beta 3 mAb, and by RGD peptides. alpha v beta 3 does not require the HHLGGAKQAGDV400-411 sequence of gamma C for binding, and alpha EC does not have such a sequence, indicating that the alpha v beta 3 binding sites are distinct from those of alpha IIb beta 3. A small fragment of gamma C (residues 148-226) supports alpha v beta 3 adhesion, suggesting that an alpha v beta 3 binding site is located within the gamma chain 148-226 region. We have reported that the CYDMKTTC sequence of beta 3 is responsible for the ligand specificity of alpha v beta 3. gamma C and alpha EC do not bind to wild-type alpha v beta 1, but do bind to the alpha v beta 1 mutant (alpha v beta 1-3-1), in which the CYDMKTTC sequence of beta 3 is substituted for the corresponding beta 1 sequence CTSEQNC. This suggests that gamma C and alpha EC contain determinants for fibrinogen's specificity to alpha v beta 3. These results suggest that fibrinogen has potentially significant novel alpha v beta 3 binding sites in gamma C and alpha EC.

Interaction of mitochondrial presequences with DnaK and mitochondrial hsp70

Mitochondrial heat shock protein 70 (mt-hsp70) functions as a molecular chaperone in mitochondrial biogenesis. The chaperone in co-operation with its co-proteins acts as a translocation motor pulling the mitochondrial precursor into the matrix. Mt-hsp70s are highly conserved when compared to the bacterial hsp70 homologue, DnaK. Here we have used DnaK as a model to study the interaction of mitochondrial presequences with mt-hsp70 applying a DnaK-binding algorithm, computer modeling and biochemical investigations. DnaK-binding motifs have been analysed on all available, statistically relevant mitochondrial presequences found in the OWL database by running the algorithm. A total of 87 % of mammalian, 97 % of plant, 71 % of yeast and 100 % of Neurospora crassa presequences had at least one DnaK binding site. Based on the prediction, five 13-mer presequence peptides have been synthesized and their inhibitory effect on the molecular chaperone (DnaK/DnaJ/GrpE) assisted refolding of luciferase has been analysed. The peptide with the highest predicted binding likelihood showed the strongest inhibitory effect, whereas the peptide with no predicted binding capacity showed no inhibitory effect. A 3D structure of the pea mt-hsp70 has been constructed using homology modeling. The binding affinities of the 13-mer presequence peptides and additional control peptides to DnaK and pea mt-hsp70 have been theoretically estimated by calculating the buried hydrophobic surface area of the peptides docked to DnaK and to the mt-hsp70 structural model. These results suggest that mitochondrial presequences interact with the mt-hsp70 during or after mitochondrial protein import.

Synthesis and antiprotozoal activities of some new triazine derivatives including a new antitrypanosomal agent: SIPI-1029

Two series of compounds, 1,2-dihydro-2,2-dimethyl-4, 6-diamino-1-(omega-haloalkyloxy)-s-triazines and O, O'-bis (4, 6-diamino-1, 2-dihydro-2, 2-disubstituted-s-triazin-l-yl) alkanediols were synthesized and tested against Plasmodium berghei and Trypanosoma evansi in mice. Most title compounds showed good antimalarial activity and compounds IIc-e showed good antitrypanosomal effect. After further studies on pharmacology, toxicology, pharmacokinetics and efficacy on infected cattles compound IIe (SIPI-1029, T-46) was shown to be a new highly active antitrypanosomal agent with low toxicity and long half life in plasma.

Specific interaction of the recombinant disintegrin-like domain of MDC-15 (metargidin, ADAM-15) with integrin alphavbeta3

MDC-15 (ADAM-15, metargidin), a membrane-anchored metalloprotease/disintegrin/cysteine-rich protein, is expressed on the surface of a wide range of cells and has an RGD tripeptide in its disintegrin-like domain. MDC-15 is potentially involved in cell-cell interactions through its interaction with integrins. We expressed a recombinant MDC-15 disintegrin-like domain as a fusion protein with glutathione S-transferase (designated D-15) in bacteria and examined its binding function to integrins using mammalian cells expressing different recombinant integrins. We found that D-15 specifically interacts with alphavbeta3 but not with the other integrins tested (alpha2beta1, alpha3beta1, alpha4beta1, alpha5beta1, alpha6beta1, alpha6beta4, alphavbeta1, alphaIIbbeta3, and alphaLbeta2). Mutation of the tripeptide RGD to SGA totally blocked binding of D-15 to alphavbeta3, suggesting that D-15-alphavbeta3 interaction is RGD-dependent. When the sequence RPTRGD is mutated to NWKRGD, D-15 is recognized by both alphaIIbbeta3 and alphavbeta3, suggesting that the receptor binding specificity is mediated by the sequence flanking the RGD tripeptide, as in snake venom disintegrins. These results indicate that the disintegrin-like domain of MDC-15 functions as an adhesion molecule and may be involved n alphavbeta3-mediated cell-cell interactions.

Soft tissue chondroma of the parapharyngeal space: a case report

Benign chondroma affecting the soft tissues is uncommon. This tumour is particularly rare in the neck. We present the first case of soft tissue chondroma arising in the parapharyngeal space of a 20-year-old man with a two-year history of a gradual sensation of a swelling in the pharynx with increasing snoring. The CT and pathological features of this lesion will be discussed. We suggest that a peroral approach should be considered for benign parapharyngeal tumour which has been demonstrated on imaging to be in the anterior parapharyngeal space, especially for tumours that are medial to the pterygoid muscles even though the tumour is a large one.

Influence of fever on biliary elements of guinea pigs

AIM: To study the influence of fever on biliary elements and gallstone formation in guinea pigs.

METHODS: Sixty guinea pigs were randomly divided and fed either a lithogenic diet (to induce gallstone formation) or a normal diet (for use as the non-gallstone controls), and each group was then subdivided into fever or non-fever subgroups. The fever condition was induced by subcutaneous injection of boiled non-fat milk (1 mL/kg, once a week for 4 wk). After 45 d, all the animals were euthanized for analysis; however, 36 h prior to euthanasia, the guinea pigs in the fever subgroups were injected subcutaneously with turpentine (1 mL/kg) to maintain the fever condition. Gallbladder lumens were examined and bile samples were analyzed.

RESULTS: Gallstone incidence was highest (40%, 6/15) in the group of animals that were fed the lithogenic diet and had fever. Compared to the non-fever subgroups, the fever subgroups had significantly higher total bile protein and bilirubin.

CONCLUSION: Fever influences biliary elements and may contribute to gallstone formation in guinea pigs.

Relationship of anesthetic activity of alkyl acetates to hydrophobicity and in vivo effect on membrane fluidity in mice

In vivo anesthetic activity of alkyl acetates in mice was studied in relation to hydrophobicity and the in vivo effect on membrane fluidity. The anesthetic potency (AD50) of alkyl acetates was determined; AD50 shows the i.p. dose required to anesthetize 50% of mice from the treated group. We used log P (n-octanol/water partition coefficient) as an operational definition of hydrophobicity. Membrane fluidity was determined using 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescence probe. Log (1/AD50) was a parabolic function of log P, and the value of log P that corresponds to the minimum AD50 was estimated to be 2.08. Brain synaptosomal membranes were prepared from mice 30 min after dosing with each of the three alkyl acetates applied at 1.5-fold AD50: n-butyl, n-amyl, and n-hexyl acetate. In each alkyl acetate group, most of the animals were anesthetized (> 68%). Decreased membrane fluidity was observed for the animals that were anesthetized while no change in the fluidity was seen for the animals that were not anesthetized. The results suggest an involvement of decreased DPH fluidity in alkyl acetate-induced anesthesia.

Structural basis of integrin-mediated signal transduction

Integrins are a family of alpha/beta heterodimers of cell adhesion receptors that mediate cell-extracellular matrix and cell-cell interactions. Both alpha and beta subunits have a large extracellular domain and a short cytoplasmic domain. The alpha subunit has seven sequence repeats of 60-70 residues in its N-terminal region. The beta-propeller model, in which seven four-stranded beta-sheets are arranged in a torus around a pseudosymmetry axis, has been proposed as a structural model of these seven repeats. Several predicted loops critical for ligand binding have been identified in the upper face of the proposed beta-propeller model. Several alpha subunits (e.g., alpha 2, alpha L and alpha M) have I-domains of about 200 residues inserted between their second and third repeats. These I-domains adopt a Rossman-fold structure and have major ligand and cation binding sites (the MIDAS site) on their surfaces. The beta subunit has an I-domain-like structure in its N-terminal region. This structure includes multiple sequences/conserved oxygenated residues critical for ligand binding (e.g., Asp-119 in beta 3), and non-conserved residues critical for ligand specificities. Several "activation-dependent" epitopes have been identified in the Cys-rich (stalk) region of beta 1. It has yet to be determined how these multiple ligand binding sites in the alpha and beta subunits are involved in ligand binding, and how conformational changes on activation/ligand occupancy relate to signal transduction.

[Nursing study of supporting aerosolized oxygen by combined drug liquid in children with intensive pneumonia]

148 cases of critical pneumonia at the same period were divided into two groups randomly and supplied by two oxygen therapeutic methods. The study group has 75 cases, whom were given aerosolized oxygen with antibacterial, antiphlogistic drugs, expectorants, antispastic and antiasthmatic drugs, and compared with 73 cases of convenient simple with aerosolized oxygen inhalation. The results showed the frequency, time and starting effect time of inhaling oxygen in two groups have significant difference (P < 0.001) and the alteration of SaO2 and the therapeutic effect in two groups also have significant difference (P < 0.05, P < 0.005 respectively). The total effectual rates of the study and control group were 94.66% and 73.94% respectively. The difference between the duration of hospitalization and the therapeutic expenditure in two groups were significance (P < 0.01, P < 0.05 respectively). The study indicated that aerosolized oxygen combined drug liquid is a better oxygen therapy method for treating pneumonia.

[Clinical study on jianfei pill in preventing and treating recurrence of infantile asthma]

OBJECTIVE

Further explore on preventing and treating recurrence of infantile asthma with TCM method and its mechanism.

METHODS

Using Jianfei Pill (JFP) which was prepared according to the therapeutic principle of strengthening the body resistance to consolidate the constitution and promoting blood circulation to remove obstruction in the channels in treating 56 patients suffering from asthma. Their pulmonary functions were observed.

RESULTS

A total effective rate of 91.1% was shown in JFP group, which was higher than that of the control group (60%), P < 0.01. In comparison with the control group, the level of serum IgA, IgG and E-rosette ascend significantly (P < 0.01). The wave amplitude of pulmonary impedance rheogram and right heart index (HI) also increased significantly (P < 0.01), while pulmonary arterial pressure (PPA) and pulmonary vascular resistance (PVR) dropped markedly (P < 0.01).

CONCLUSION

JFP might work by means of enhancing the immune function and improving the pulmonary microcirculation to control chronic bronchial inflammation and reduce its reactivity to prevent the relapse of asthma.

Experimental study of double-lumen, two-stage endotracheal tube during conventional mechanical ventilation in rabbits

OBJECTIVE

To evaluate the effects of a double-lumen, two-stage endotracheal tube on gas exchanges (ventilatory efficiency) during conventional mechanical ventilation, using a ventilator in rabbits.

DESIGN

Prospective, randomized, crossover laboratory animal trial.

SETTING

Research laboratory in the Beijing Children's Hospital.

SUBJECTS

Five adult New Zealand rabbits, weighing 3.2 to 3.7 kg.

INTERVENTIONS

A new type of endotracheal tube-the double-lumen two-stage endotracheal tube-was designed and tested for ventilation efficiency in rabbits with normal and injured lungs. The new tube (size 3.0 mm) was made out of two Portex endotracheal tubes (size 3.0 mm) by adhering two vertical cross-sections at the distal end of the two tubes. The new tube and a conventional endotracheal tube of the same size (inner diameter 3.0 mm) were randomly used in pressure control ventilation. Each trial was maintained for 30 mins.

MEASUREMENTS AND MAIN RESULTS

Effects from the two endotracheal tubes on pulmonary mechanics, hemodynamics, and gas exchange were observed. We measured peak inspiratory pressure, positive end-expiratory pressure (PEEP), intrinsic PEEP, mean airway pressure, and arterial blood and mixed expired gas variables (Pao2, Paco2, pH, and mixed expired gas Pco2). The new endotracheal tube acutely increased CO2 elimination in all animals with normal and injured lungs. Paco2 decreased from 46 +/- 4 to 36 +/- 5 torr (6.1 +/- 0.5 to 4.8 +/- 0.7 kPa; p < .01) in normal lungs and from 48 +/- 5 to 36 +/- 5 (6.4 +/- 0.7 to 4.8 +/- 0.7 kPa; p < .01). Meanwhile, tidal volume fraction decreased from 0.48 +/- 0.07 to 0.35 +/- 0.05 (p < .01) and from 0.56 +/- 0.07 to 0.40 +/- 0.07 (p < .01) in normal and injured lungs, respectively. Intrinsic PEEP of the new tube slightly increased, but there were no significant differences in comparison with the conventional tube.

CONCLUSION

Compared with the conventional endotracheal tube, the new double-lumen, two-stage endotracheal tube reduced Paco2 by decreasing anatomical deadspace in rabbits with normal and injured lungs under pressure control ventilation, thus enhancing ventilatory efficiency and reducing ventilator-induced injury.

Intrinsic injury signals enhance growth, survival, and excitability of Aplysia neurons

Neurons undergo extensive changes in growth and electrophysiological properties in response to axon injury. Efforts to understand the molecular mechanisms that initiate these changes have focused almost exclusively on the role of extrinsic signals, primarily neurotrophic factors released from target and glial cells. The objective of the present investigation was to determine whether the response to axonal injury also involves intrinsic axoplasmic signals. Aplysia neurons were removed from their ganglia and placed in vitro on a substratum permissive for growth, but in the absence of glia and soluble growth factors. Under these conditions, neurites emerged and grew for approximately 4 d. Once growth had ceased, the neurites were transected. In all, 46 of 50 cells regenerated, either by resorbing the remaining neurites and elaborating a new neuritic arbor or by merely replacing the neurites that had been severed. Cut cells also exhibited enhanced excitability and, paradoxically, prolonged survival, when compared with uninjured neurons. These findings indicate that axons contain intrinsic molecular signals that are directly activated by injury to trigger changes underlying regeneration and compensatory plasticity.

Effects of halothane, isoflurane and sevoflurane on calcium-related contraction in porcine coronary arteries

BACKGROUND

Volatile anaesthetics have a direct inhibitory effect upon epicardial coronary arterial smooth muscles (1-4). The site and mode of their action at the cellular level need to be clarified, which was the purpose of our study. The present investigation attempted to answer the question in what way volatile anaesthetics influence Ca(2+)-related contraction in isolated porcine epicardial coronary to understand their intracellular mechanism.

METHODS

Isolated helical strips of porcine epicardial coronary artery without endothelium were suspended for isotonic contraction recordings in Krebs-Ringer's solution. 9.4 x 10(-2) MK+, 2.5 x 10(-3) M Ca(2+)-induced shortening of the strips was regarded as the reference value (100%). After incubation in Ca(2+)-free solution with 10(-3) M ethlene glycol bis (beta-aminoethyl ether)-N, N-tetraacetic acid (EGTA) for 60 minutes, the muscle strips were exposed to increasing Ca2+ concentrations (10(-4)-10(-2)) either in the presence or absence of 1.5 or 2.5 minimum alveolar concentration (MAC) halothane, isoflurane or sevoflurane, with 9.4 x 10(-2) M K+ bath solution.

RESULTS

All three drug groups produced apparent biphasic effects with a cumulative increase of Ca2+ concentration compared with control groups. An initial increase at low Ca2+ concentration was followed by a decrease of Ca(2+)-activated contractions. Isoflurane affected Ca(2+)-induced contraction significantly more than halothane and sevoflurane.

CONCLUSIONS

The results imply that volatile anaesthetics influence Ca(2+)-dependent activity of coronary smooth muscle by complex mechanisms, which involve promotion of intracellular Ca2+ release and other mechanisms that alter sensitivity to calcium.

In vitro influences of alcohols on mouse synaptosomes, and structure-activity relationships

Little information is available on the structure-central nervous system membrane toxicity relationship of alcohols. The purpose of the present study was to study in vitro influence of alcohols (n = 20) on the activity of the toxic indicator Na+/K(+)-adenosine triphosphatase (Na+/K(+)-ATPase) and acetylcholinesterase (AchE), and membrane fluidity in mouse brain synaptosomes, in terms of the structure-activity relationship. The potency of inhibition for the enzymes (IC50) and the potency of increasing membrane fluidity (IC12.5) were determined experimentally, and n-octanol/water partition coefficient (P) and the steric constant Taft Es are cited from the literature. Regression analysis revealed that log 1/IC50 for Na+/K(+)-ATPase is a function of log P and Taft Es. The situation was true for AchE activity. The results indicate that the hydrophobicity expressed as log P and the steric effect of the alcohols play an important role in inhibiting both enzyme activities. A linear relationship between log 1/IC12.5 for membrane fluidity and log P is shown, indicating a significant effect of the alcohols on membrane fluidity. Based on these results, it is suggested that the alcohols inhibit the Na+/K(+)-ATPase and AchE activity through a direct action on the enzymes and/or through changing the membrane fluidity.

Axoplasm enriched in a protein mobilized by nerve injury induces memory-like alterations in Aplysia neurons

Axon regeneration after injury and long-term alterations associated with learning both require protein synthesis in the neuronal cell body, but the signals that initiate these changes are largely unknown. Direct evidence that axonal injury activates molecular signals in the axon was obtained by injecting axoplasm from crushed or uncrushed nerves into somata of sensory neurons with uncrushed axons. Those injected with crush axoplasm behaved as if their axons had been crushed, exhibiting increases in both repetitive firing and spike duration, and a decrease in spike afterhyperpolarization 1 d after injection. Because similar changes occur in the same cells after learning, these data suggest that some of the long-lasting adaptive changes that occur after injury and learning may be induced by common axoplasmic signals. Since the signals in axoplasm must be conveyed to the cell soma, we have begun to test the hypothesis that at least some of these signals are proteins containing a nuclear localization signal (NLS). Axoplasmic proteins at the crush site and those that accumulated at a ligation proximal to the crush were probed with an antibody to an amino acid sequence (sp) containing a NLS that provides access to the retrograde transport/nuclear import pathway. One protein, sp97, displayed properties expected of an axonal injury signal: it responded to injury by undergoing an anterograde-to-retrograde change in movement and, when the ligation was omitted, it was transported to the cell bodies of the injured neurons.

Streptococcus pyogenes type IIa IgG Fc receptor expression is co-ordinately regulated with M protein and streptococcal C5a peptidase

Streptococcus pyogenes is an important agent of human disease which expresses a variety of proteins and polysaccharides on its surface. Surface molecules M protein and streptococcal C5a peptidase (SCPA) are virulence factors which undergo concurrent phase variation and are under the co-ordinate control of the virR locus. Most opacity factor-positive (OF+) strains of S. pyogenes also express IgG Fc receptor proteins on their surface. These studies were initiated to determine whether the type IIa Fc receptor on the surface of S. pyogenes phase-varies with members of this regulatory circuit. Several methods were applied to M+ and M- variant strains to evaluate this question. (i) Immunoblot assays quantified Fc receptors on whole cells by using human IgG myeloma protein and receptor-specific antibody. M+ strains bound IgG and antibody specific for Fc protein, whereas M- strains did not. (ii) Enzyme-linked immunosorbent assays quantified Fc receptor antigen expression and showed that M+ strains produce more Fc receptor protein than their M- derivatives. (iii) Quantitative RNA dot blots showed that the message for the Fc receptor gene (fcrA) was reduced in M- strains. RNA from M+ strains hybridized to the fcrA probe at a greater dilution than that from their M- counterparts. (iv) Northern hybridization showed that the fcrA transcript is 1200 nucleotides in size and distinct from transcripts for M and SCPA proteins. These data are evidence for the co-ordinate transcriptional control of the Fc receptor, M protein, and SCPA and show that these proteins co-ordinately phase-vary within the same regulatory circuit.

Endogenous axoplasmic proteins and proteins containing nuclear localization signal sequences use the retrograde axonal transport/nuclear import pathway in Aplysia neurons

When the nuclear localization signal peptide (sp) of the SV 40 large T antigen was coupled to human serum albumin (HSA), rhodaminated (r), and microinjected into axons of Aplysia neurons in vitro, the rHSA-sp was conveyed through the axon to the cell body and then into the nucleus (Ambron et al., 1992). But since rHSA-sp is an artificial construct, we needed to determine whether naturally occurring nuclear proteins use this pathway. We therefore injected calf thymus histone H-1 and Xenopus oocyte nucleoplasmin into axons. By 3 hr both were retrogradely transported and targeted into the nucleus, though histone H-1 less efficiently than rHSA-sp or nucleoplasmin. In contrast, neither rHSA, nor rHSA conjugated to a peptide with a random distribution of basic amino acids, was transported or imported. To see if proteins that use the pathway remain intact, we coupled sp to HRP. When injected into varicosities, the HRP-sp was transported/imported to the nucleus, where it was enzymatically active. A key issue was to determine whether endogenous proteins use this pathway. Consequently, axoplasm was extruded from Aplysia nerves and the proteins were fractionated by size. SDS-PAGE and Western blots showed that two fractions contained proteins that were recognized by an affinity-purified antibody to sp: fraction 3 included sp83, and fraction 4 contained sp75. In addition, these two proteins were found in nuclei isolated from neurons. To assess transport, the total proteins in the fractions were rhodaminated and injected into varicosities. Fraction 3, but not fraction 4, contained protein that was transported through the axon to the nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)

A new macrophage differentiation antigen which is a member of the scavenger receptor superfamily

The antibodies Ki-M8, Ber-Mac3, GHI/61 and SM4 define a human macrophage-associated antigen with a relative molecular mass of 130,000 which we designate M130. The protein was purified by immunoaffinity chromatography and an N-terminal and three internal amino acid sequences were obtained. A cDNA fragment was initially obtained by polymerase chain reaction (PCR) using reverse-translated primers. Several variant cDNA clones, derived from alternative spliced messages, were obtained from a lipopolysaccharide-stimulated human monocyte library and were sequenced. The relative abundance of these variants was evaluated by a series of overlapping PCR reactions. The size of the most representative cDNA is 3.7 kb and closely agrees with the mRNA size of 3.8 kb determined by Northern blot analysis. The membrane protein encoded contains a leader peptide of 40 residues, a putative extracellular domain of 1003 residues, followed by a hydrophobic segment of 24 residues and a cytoplasmic domain of 49 residues. The extracellular domain was found to contain nine repeating elements, of about 110 residues, which are similar to those of the scavenger receptor superfamily.

[Clinical and experimental study on yifei jianshen mixture in preventing and treating infantile repetitive respiratory infection]

In recent years, the incidence of infantile repetitive respiratory infection has been increasing. In order to prevent and treat this disease, the authors suggest that pathogenesis of this disease is mainly due to insufficiency of Lung, Spleen and Kidney, which caused the Qi Deficiency and Blood Stasis Syndrome, and thus formulated Yifei Jianshen Mixture (YFJSM). The clinical and experimental study was carried out accordingly. The results showed that this mixture could increase the immune function of human body, and improve microcirculation, and has the function of warming up Yang and replenishing Qi, nourishing blood and activating blood circulation and eventually of preventing and treating diseases. 305 cases were clinically observed, the total effective rate being 95.1%. The effect of treatment is obviously better than that of control using Yupingfeng powder (P < 0.01). The adrenocortical function, plasma nucleotide, immune function, microcirculation and others were the main technical indexes of models, which were nearly the same as clinical study. The toxicity test also showed that the YFJSM was non-toxic and had no side effect. The study proved that the mixture was highly effective and had no side effect.

Selection and identification of antigenic determinant of Mycobacterium tuberculosis H37Ra strain

A new procedure for the selection of the antigenic determinant of Mycobacterium tuberculosis H37Ra strain is described. The bacterium components destroyed by ultrasonic were isolated by 15% SDS-PAGE, transferred onto nitrocellulose membrane, immunostained with McAbs against H37Ra. One McAb-positive fragment was obtained using the Western blot analysis. The molecular weight of the antigenic determinant is 35,000 dalton. The antigenic determinant is of immunological reactivity with McAb and TB patients' sera in dot-immunoassay and demonstrated in delayed skin tests in guinea pigs. The amino acid composition of the antigenic determinant was analysed. These suggest that the Western blot analysis may be a useful tool for the analysis of the antigenic determinant.

Derivatives of CAP having no solvent-accessible cysteine residues, or having a unique solvent-accessible cysteine residue at amino acid 2 of the helix-turn-helix motif

The Escherichia coli catabolite gene activator protein (CAP) is a helix-turn-helix motif sequence-specific DNA binding protein. CAP contains a unique solvent-accessible cysteine residue at amino acid 10 of the helix-turn-helix motif. In published work, we have constructed a prototype semi-synthetic site-specific DNA cleavage agent from CAP by use of cysteine-specific chemical modification to incorporate a nucleolytic chelator-metal complex at amino acid 10 of the helix-turn-helix motif [Ebright, R., Ebright, Y., Pendergrast, P.S. and Gunasekera, A., Proc. Natl. Acad. Sci. USA 87, 2882-2886 (1990)]. Construction of second-generation semi-synthetic site-specific DNA cleavage agents from CAP requires the construction of derivatives of CAP having unique solvent-accessible cysteine residues at sites within CAP other than amino acid 10 of the helix-turn-helix motif. In the present work, we have constructed and characterized two derivatives of CAP having no solvent-accessible cysteine residues: [Ser178]CAP and [Leu178]CAP. In addition, in the present work, we have constructed and characterized one derivative of CAP having a unique solvent-accessible cysteine residue at amino acid 2 of the helix-turn-helix motif: [Cys170;Ser178]CAP.