Focal adhesion kinase (pp125FAK) cleavage and regulation by calpain

Focal adhesion kinase (125 kDa form; pp125FAK) is a widely expressed non-receptor tyrosine kinase that is implicated in integrin-mediated signal transduction. We have identified a novel means of pp 125FAK regulation in human platelets, in which this kinase undergoes sequential proteolytic modification from the native 125 kDa form to 90, 45 and 40 kDa fragments in thrombin-, collagen- and ionophore A23187-stimulated platelets. The proteolysis of pp125FAK was prevented by pretreating platelets with the calpain inhibitors calpeptin or calpain inhibitor-1, and was reproduced in vitro by incubating immunoprecipitated pp125FAK with purified calpain. Proteolysis of pp125FAK resulted in a dramatic reduction in its autokinase activity and led to its dissociation from the cytoskeletal fraction of platelets. These studies define a novel signal-terminating role for calpain, wherein proteolytic modification of pp125FAK attenuates its autokinase activity and induces its subcellular relocation within the cell.

Stationary phase-associated protein expression in Mycobacterium tuberculosis: function of the mycobacterial alpha-crystallin homolog

The majority of active tuberculosis cases arise as a result of reactivation of latent organisms which are quiescent within the host. The ability of mycobacteria to survive extended periods without active replication is a complex process whose details await elucidation. We used two-dimensional gel electrophoresis to examine both steady-state protein composition and time-dependent protein synthetic profiles in aging cultures of virulent Mycobacterium tuberculosis. At least seven proteins were maximally synthesized 1 to 2 weeks following the end of log-phase growth. One of these proteins accumulated to become a predominant stationary-phase protein. N-terminal amino acid sequencing and immunoreactivity identified this protein as the 16-kDa alpha-crystallin-like small heat shock protein. The gene for this protein was shown to be limited to the slowly growing M. tuberculosis complex of organisms as assessed by Southern blotting. Overexpression of this protein in wild-type M. tuberculosis resulted in a slower decline in viability following the end of log-phase growth. Accumulation of this protein was observed in log-phase cultures following a shift to oxygen-limiting conditions but not by other external stimuli. The protein was purified to homogeneity from overexpressing M. smegmatis in two steps and shown to have a significant ability to suppress the thermal denaturation of alcohol dehydrogenase. Collectively, these results suggest that the mycobacterial alpha-crystallin protein may play a role in enhancing long-term protein stability and therefore long-term survival of M. tuberculosis.

[A study of treatment modalities for nonresectable primary liver cancer]

This paper reports the results of multimodality treatment in 200 patients with nonresectable primary liver carcinoma (PLC) from April 1964 to July 1993. PLC was verified histologically in all cases. They were divided into two groups according to the methods of treatment. In group 1, 115 cases received anticancer agents by hepatic artery infusion (HAI). The 1- and 2-year survival rate was 10.4% and 1.7%, respectively and only one patient survived 65 months. In group 2, 85 cases received multimodality treatments by various combinations of hepatic artery chemoembolization (HACE), hepatic artery ligation (HAL), microwave coagulation (MIC) of tumor and ethanol injection into tumor (EIT). The 1-, 2-, 3- and 5-year survival rate was 34.1%, 21.2%, 12.0% and 6.7%, respectively. Five patients had been alive for 41 to 63 months and second-stage hepatic resection performed in another 6 patients. The results suggest that multimodality treatment is an effective approach to improve the long-term survival of patients with nonresectable PLC.

[Study on the mutagenicity of salted pork from high risk area of stomach cancer and its relation to pathological changes of gastric mucosa]

To investigate the relations between salted pork (SP) from Zhuanghe (a high risk area of stomach cancer in northeast China) and stomach cancer three studies had been done, including the mutagenicity of SP, the effect of SP on the gastric mucosa of residents in Zhuanghe area who had consumed SP for 10-30 years and the mucosal lesions of dogs taking SP. The results showed that the extract of SP was a strong mutagen in strain TA98 and led to increased micro-nuclei rate (MNR) and micro-nuclei cell rate (MNCR) of V79 cell at a dose range of 20-80 mumol/ml. There were dose-effect relations between SP and MNR, MNCR. The results also indicated that pathological changes of gastric mucosa of residents who consumed SP had remarkable difference from those of the control group. In people who had consumed SP for 10 years, mucosal lesions including necrosis and erosion were seen; for those consumed SP for 10+(-)20 years, there were hyperplasia and dysplasia and those for 20+(-)30 years different degrees of dysplasia and even malignant change could be observed. The research also found that SP had damaging effect on gastric mucosa in dogs taking SP. The mucosal lesions became more severe with time of feeding SP. The conclusion is that SP is a strong mutagen, long-term exposure to SP may result in repeated gastric mucosal damage and repair, and finally in severe dysplasia and malignancy.

[Diagnostic value of exercise diffusion capacity test on diffuse pulmonary fibrosis]

Diffusion capacity for carbon monoxide of the lung (DLCO) before-and-after exercise test and 5 routine pulmonary function tests were conducted in 16 patients with diffuse pulmonary fibrosis (DPF), 19 patients with interstitial pneumonia (IP), 17 patients with COPD, and 22 normal subjects. The data showed: in normal subjects the DLCO after exercise increased significantly compared with before (P < 0.001). But in DPF group the DLCO before exercise was below the normal range, and it went down further after exercise, the decreasing rate being 17.95% (P < 0.001). The DLCO in IP and COPD groups did not significantly change before and after the exercise. Two cases of interstitial pneumonia, who had a reduced DLCO after exercise, were followed up for 0.5-1.0 year, and both patients developed into DPF by that time. The results suggest that the DLCO measure before and after exercise test may have important value for DPF diagnosis, and a reduced DLCO after exercise test in IP patients may warn the development from IP into DPF.

[Giant axonal neuropathy. A case report]

We report a sporadic case of giant axonal neuropathy (GAN) starting in a 5-year-old boy with gait disturbance. At the age of 10 years he showed signs of a sensomotoric polyneuropathy and central neurological symptoms: intention tremor, nystagmus and visual disturbance. The boy also had curly hair. Sural nerve biopsy showed many giant axons with accumulation of microfilaments, which were also found in cytoplasma of Schwann cells, endothelial cells and fibrocytes. Similar changes were detected in endothelial cells of a muscle biopsy, which additionally displayed neurogenic atrophy and target fibers. Immunohistochemically, desmin, vimentin, heat shock protein 70, and ubiquitin were not detectable in giant axons, which, however, contained neurofilament protein 68, 200 and beta-tubulin. Our case shows that careful ultrastructural examination of a muscle biopsy may point to the diagnosis of GAN.

[Measurement of maximal inspiratory flow and forced inspiratory capacity and its clinical application]

The methods of measuring the maximal inspiratory flow (V(imax)) and the forced inspiratory capacity (FIC) via forced inspiratory capacity-time curve (FIC-t curve) were investigated. Both V(imax) and FIC were measured in 35 normal subjects and 89 patients with chronic obstructive pulmonary disease (COPD). The maximal inspiratory pressure (MIP) was measured simultaneously at function residual capacity(FRC) level by modified Black Method. The results showed that there is a linear relationship between MIP and V(imax) or FIC in both normal subjects and patients with COPD. Normal subjects had a mean V(imax) and FIC much higher than those of patients with COPD. The values of V(imax) and FIC in patients were also, significantly correlated to the severity of COPD. So we suggest that both V(imax) and FIC be used as clinical indices to reflect inspiratory muscles strength.

A poroelastic finite element formulation including transport and swelling in soft tissue structures

A field theory is presented for the study of swelling in soft tissue structures that are modeled as poroelastic materials. As a first approximation, soft tissues are assumed to be linear isotropic materials undergoing infinitesimal strains. Material properties are identified that are necessary for the solution of initial boundary value problems where swelling and convection are significant. A finite element model is developed that includes the solid displacements, the relative fluid displacements, and a representative concentration as the primary unknowns. A numerical example is presented based on a triphasic model. The finite model simulates a typical experimental protocol for soft tissue testing and demonstrates the interaction and coupling associated with relative fluid motion and swelling in a deforming poroelastic materiaL The theory and finite element model provide a starting point for nonlinear porohyperelastic transport-swelling analyses of soft tissue structures that include finite strains in anisotropic materials.

Methylmercury acts at multiple sites to block hippocampal synaptic transmission

To explore the mechanisms by which methylmercury (MeHg) blocks central synaptic transmission, intracellular recordings of action potentials and resting membrane potentials were made in CA1 neurons of rat hippocampal slices. At 4 to 100 microM, MeHg blocked action potentials in a concentration- and time-dependent manner. MeHg also depolarized Ca1 neuronal membranes. However, this effect occurred more slowly than block of action potentials because the resting membrane potentials remained unchanged when threshold stimulation-evoked action potentials were blocked. Thus, MeHg may initially alter the threshold level of neuronal membrane excitability and subsequently depolarize the membrane leading to block of synaptic transmission. To identify potential sites of action of MeHg, effects of MeHg on the responses of CA1 neurons to orthodromic stimulation of Schaffer collaterals, antidromic stimulation of the alveus, direct injection of current at cell soma and iontophoretic application of glutamate were compared. At 20 and 100 microM, MeHg blocked action potentials evoked by stimulation of Schaffer collaterals and by current injection at the cell soma at similar times. In contrast, action potentials evoked by stimulation of the alveus were blocked more rapidly by 100 microM MeHg than were action potentials evoked by current injection at CA1 neuronal soma. MeHg also blocked the responses of CA1 neurons to iontophoresis of glutamate, but time to block of these responses was slower than block of the corresponding orthodromically-evoked responses by stimulation of Schaffer collaterals. Compared to excitatory postsynaptic potentials, inhibitory postsynaptic potentials appeared to be more sensitive to MeHg, because block of inhibitory postsynaptic potentials occurred before block of excitatory postsynaptic potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

An essential role for lysophosphatidylcholine in the inhibition of platelet aggregation by secretory phospholipase A2

The release of secretory phospholipase A2 (sPLA2) into the mammalian circulation may contribute to the development of hemorrhagic and inflammatory diseases. sPLA2 has previously been shown to alter the behavior of platelets, leukocytes, and endothelial cells, although the molecular basis for these cellular effects has not been established. Our studies indicate that the inhibition of platelet aggregation by snake, bee venom, and pancreatic sPLA2 is dependent on a plasma cofactor. This cofactor resides within the lipoprotein fraction of plasma, with 54%, 31%, and 11% of the activity present in the high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low density lipoprotein (VLDL) fractions, respectively. Delipidation of HDL and LDL was associated with the complete loss of platelet-inhibitory activity. Incubation of purified sPLA2 with the HDL fraction of plasma resulted in the time-dependent generation of lysophosphatidylcholine (lysoPC). The formation of lysoPC correlated with the inhibition of platelet aggregation. Purified lysoPC (10 to 100 micrograms/mL) inhibited platelet aggregation and dense granule release induced by thrombin (0.05 U/mL), collagen (1 micrograms/mL), ionophore A23187 (2 mumol/L), ADP (12.5 mumol/L), and adrenaline (3.2 mumol/L). The inhibition of platelet aggregation by lysoPC was dose-dependent and correlated with decreased fibrinogen binding to glycoprotein IIb-IIIa. Our studies indicate that the enzymatic generation of lysoPC from plasma lipoproteins is essential for the sPLA2-mediated inhibition of platelet activation in the presence of albumin. These results raise the possibility that the toxic effects of circulating sPLA2 may be due in part to the generation of the bioactive lysophospholipid, lysoPC.

The biosynthesis of cyclopropanated mycolic acids in Mycobacterium tuberculosis. Identification and functional analysis of CMAS-2

The major mycolic acid produced by Mycobacterium tuberculosis contains two cis-cyclopropanes in the meromycolate chain. The gene whose product cyclopropanates the proximal double bond was cloned by homology to a putative cyclopropane synthase identified from the Mycobacterium leprae genome sequencing project. This gene, named cma2, was sequenced and found to be 52% identical to cma1 (which cyclopropanates the distal double bond) and 73% identical to the gene from M. leprae. Both cma genes were found to be restricted in distribution to pathogenic species of mycobacteria. Expression of cma2 in Mycobacterium smegmatis resulted in the cyclopropanation of the proximal double bond in the alpha 1 series of mycolic acids. Coexpression of both cyclopropane synthases resulted in cyclopropanation of both centers, producing a molecule structurally similar to the M. tuberculosis alpha-dicyclopropyl mycolates. Differential scanning calorimetry of purified cell walls and mycolic acids demonstrated that cyclopropanation of the proximal position raised the observed transition temperature by 3 degrees C. These results suggest that cyclopropanation contributes to the structural integrity of the cell wall complex.

Effects of hypoxic endothelial cell conditioned medium on proliferation and collagen synthesis of smooth muscle cells and inhibitory effects of radix salviae miltiorrhizae

The effects of hypoxic endothelial cell conditioned medium (HECCM) on proliferation and collagen synthesis of cultured porcine pulmonary arterial smooth muscle cells (PASMCs) were studied by 3H-thymidine (3H-TdR) and 3H-proline incorporations, image analysis for determination of DNA content and colorimetric assay using MTT, and the inhibitory effects of radix salviae miltiorrhizae (RSM) on them were also investigated. The results showed that HECCM could induce enhancement of the enzymatic activity of mitochondria, increase of the nucleic DNA content and increases of the 3H-TdR and 3H-proline incorporation in PASMCs. The 3H-proline incorporation in PASMCs cultured in HECCM was 1.83 times as much as that cultured in normoxic endothelial cell conditioned medium (NECCM). Compared with the control, Chinese herb medicine RSM could inhibit the proliferation of PASMCs cultured in HECCM and decrease the 3H-proline incorporation in PASMCs cultured in both HECCM and NECCM (P < 0.001). However, RSM had no effects on the nucleic DNA content and 3H-TdR incorporation into DNA of PASMCs cultured in NECCM. It suggests that hypoxia may stimulate the endothelia to synthesize and secrete some cytokines which can stimulate the proliferation and the synthesis of collagen of PASMCs and RSM can inhibit this process.

Serologic responses of infertile women to the 60-kd chlamydial heat shock protein (hsp60)

OBJECTIVE

To determine whether women with Chlamydia trachomatis-associated tubal infertility are more likely than other infertile women to have antibodies to a particular region of the 60-kd chlamydial heat shock protein, hsp60.

DESIGN

Serologic responses to the chlamydial hsp60 were examined in 43 infertile women seropositive for Chlamydia trachomatis, including 21 women with tubal infertility, 13 women with endometriosis, and 9 women with other causes of infertility. Antibody responses were localized to regions of hsp60 using five nonoverlapping recombinant polypeptides.

RESULTS

Sixteen women with tubal infertility had anti-hsp60 antibodies compared with seven women with endometriosis and two women with other causes of infertility. Antibodies of 11 women with tubal infertility reacted predominantly with a region of hsp60 containing amino acids (201 to 300) compared with 1 women without tubal infertility. In contrast, antibodies that localized to the carboxyl terminus, amino acids (401 to 544), were seen equally in all groups.

CONCLUSIONS

Among seropositive infertile women, antibodies that localized to amino acids (201 to 300) were immunodominant in those with tubal infertility but not in those with infertility due to other causes.

[Simultaneous bilateral total knee replacement for the patients with serious rheumatoid disease]

This retrospective study reviews 57 patients with serious rheumatoid disease who had bilateral total knee arthroplasties simultanneously between 1987 and 1994. The short follow-up results revealed that there was no increase in complications in the patients with simultaneous bilateral procedures, and nearly identical postoperative results to those observed among patients with single joint replacement. Advantage of simultaneous bilateral total arthroplasty include reduction in hospital cost, the need for less invasive surgical event and the ability to rehabilitate the patient symmetrically.

[Preoperative evaluation of hepatic functional reserve for patients with primary liver carcinoma]

The retention rate of indocyanine green at 15 minutes (ICGR15) and routine hepatic function tests were performed preoperatively in 122 cases of patients with primary liver carcinomas in order to evaluate the hepatic functional reserve. These patients were divided into 3 groups according to the post-operative changes of hepatic function. 87, 24 and 11 cases showed good recovery (group good), mild liver dysfunction (group mild) and severe liver dysfunction (group severe) respectively, after operation. The differences of Pugh's points, ALT, ALP and gamma-GT between each two groups were not significant. But, the differences of ICGR15 were very significant. We also divided all cases into 3 groups according to the value of ICGR15. The incidence of liver dysfunction was 6.0% in group A (ICGR15 < 10.0%), 27.8% in group B (ICGBR15 = 10.0%-20.0%) and 76.5% in group C (ICGR15 > 20.0%), respectively. The difference of the incidences of liver dysfunction in these 3 groups was very significant. The higher the ICGR15, the more the incidence of liver dysfunction. These results demonstrated that ICGR15 is a good indicator to judge hepatic functional reserve for patients with primary liver carcinoma.

Subnanosecond polarized fluorescence photobleaching: rotational diffusion of acetylcholine receptors on developing muscle cells

Polarized fluorescence recovery after photobleaching (PFRAP) is a technique for measuring the rate of rotational motion of biomolecules on living, nondeoxygenated cells with characteristic times previously ranging from milliseconds to many seconds. Although very broad, that time range excludes the possibility of quantitatively observing freely rotating membrane protein monomers that typically should have a characteristic decay time of only several microseconds. This report describes an extension of the PFRAP technique to a much shorter time scale. With this new system, PFRAP experiments can be conducted with sample time as short as 0.4 microseconds and detection of possible characteristic times of less than 2 microseconds. The system is tested on rhodamine-alpha-bungarotoxin-labeled acetylcholine receptors (AChRs) on myotubes grown in primary cultures of embryonic rat muscle, in both endogenously clustered and nonclustered regions of AChR distribution. It is found that approximately 40% of the AChRs in nonclustered regions undergoes rotational diffusion fast enough to possibly arise from unrestricted monomer Brownian motion. The AChRs in clusters, on the other hand, are almost immobile. The effects of rat embryonic brain extract (which contains AChR aggregating factors) on the myotube AChR were also examined by the fast PFRAP system. Brain extract is known to abolish the presence of endogenous clusters and to induce the formation of new clusters. It is found here that rotational diffusion of AChR in the extract-induced clusters is as slow as that in endogenous clusters on untreated cells but that rotational diffusion in the nonclustered regions of extract-treated myotubes remains rapid.

Disparate responses to oxidative stress in saprophytic and pathogenic mycobacteria

To persist in macrophages and in granulomatous caseous lesions, pathogenic mycobacteria must be equipped to withstand the action of toxic oxygen metabolites. In Gram-negative bacteria, the OxyR protein is a critical component of the oxidative stress response. OxyR is both a sensor of reactive oxygen species and a transcriptional activator, inducing expression of detoxifying enzymes such as catalase/hydroperoxidase and alkyl hydroperoxidase. We have characterized the responses of various mycobacteria to hydrogen peroxide both phenotypically and at the levels of gene and protein expression. Only the saprophytic Mycobacterium smegmatis induced a protective oxidative stress response analogous to the OxyR response of Gram-negative bacteria. Under similar conditions, the pathogenic mycobacteria exhibited a limited, nonprotective response, which in the case of Mycobacterium tuberculosis was restricted to induction of a single protein, KatG. We have also isolated DNA sequences homologous to oxyR and ahpC from M. tuberculosis and Mycobacterium avium. While the M. avium oxyR appears intact, the oxyR homologue of M. tuberculosis contains numerous deletions and frameshifts and is probably nonfunctional. Apparently the response of pathogenic mycobacteria to oxidative stress differs significantly from the inducible OxyR response of other bacteria.

Identification of a gene involved in the biosynthesis of cyclopropanated mycolic acids in Mycobacterium tuberculosis

Mycolic acids represent a major constituent of the mycobacterial cell wall complex, which provides the first line of defense against potentially lethal environmental conditions. Slow-growing pathogenic mycobacteria such as Mycobacterium tuberculosis modify their mycolic acids by cyclopropanation, whereas fast-growing saprophytic species such as Mycobacterium smegmatis do not, suggesting that this modification may be associated with an increase in oxidative stress experienced by the slow-growing species. We have demonstrated the transformation of the distal cis double bond in the major mycolic acid of M. smegmatis to a cis-cyclopropane ring upon introduction of cosmid DNA from M. tuberculosis. This activity was localized to a single gene (cma1) encoding a protein that was 34% identical to the cyclopropane fatty acid synthase from Escherichia coli. Adjacent regions of the DNA sequence encode open reading frames that display homology to other fatty acid biosynthetic enzymes, indicating that some of the genes required for mycolic acid biosynthesis may be clustered in this region. M. smegmatis overexpressing the cma1 gene product significantly resist killing by hydrogen peroxide, suggesting that this modification may be an important adaptation of slow-growing mycobacteria to oxidative stress.

[Measurement of the reserve function of inspiratory muscle and its clinical significance]

The principles of measuring inspiratory muscle tension-time index (TTim) and the ratio of the works of inspiration over the maximal works of inspiration (Wi/Wi(max)) were investigated and their formulae were deduced, i.e. TTim = (Pi x Ti)/(MIP x Ttot) and Wi/Wi(max) = (Pi x VT)/(MIP x IC). The importance of the inspiratory pressure and the maximal inspiratory pressure (MIP) measured at function residual capacity (FRC) level was emphasized. Both TTim and Wi/Wi(max) were measured in 35 normal subjects and 89 patients with chronic obstructive pulmonary disease (COPD). The results showed that normal value of TTim was 0.0253 +/- 0.0055 which corresponds to the normal value of the diaphragm tension-time index (TTdi = 0.02-0.03) reported by Bellemare. Patients with COPD had a mean TTim much higher than that of normals (P < 0.01). The works of inspiration (Wi) in patients with COPD increased, while the maximal works of inspiration (Wi(max)) declined, so Wi/Wi(max) became significantly greater than that of normals (P < 0.01). The results also showed that there was a linear relationship between Pi/Pimax and TTim or Wi/Wimax (r = 0.7891, 0.9738, 0.6459, 0.9327, P < 0.01). Therefore, we suggest that both TTim and Wi/Wimax can be used as clinical indices to reflect the reserve function of inspiratory muscles.

Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin

Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context of previous work, suggest that binding of GRB2/Sos to Shc may be the predominant mechanism whereby insulin as well as cytokine receptors activate Ras.