Pre-operative estimation of complete resection for patients with oesophageal carcinoma

Three hundred and seventy-nine patients were studied retrospectively regarding the possibility of a complete resection of the oesophageal carcinoma based on the combined findings of pre-operative oesophagogoraphy and computed tomography (CT). One hundred and four out of 129 patients (96.1%) having lesions which did not demonstrate all three of the aforementioned factors (a lesion shorter than 8 cm, a normal oesophageal axis, and normal contact of the lesion with neighboring organs in CT) underwent a complete resection of the oesophageal lesion. Fifty-three percent of the patients (52/97) with a lesion showing only one of these factors had a complete resection. Whereas, on the other hand, a complete removal of the malignancy was only possible in 22% of the patients with two or all three of the findings. Moreover, as a result of further analysis limited for resected cases, the number of positive factors in these pre-operative findings correlated with the advancement of the surgical stage, which reflected a curability in surgery and a rate of postoperative complications. In order to make adequate plans for the treatment of patients with advanced oesophageal cancer, the finding of (i) the length of lesion, (ii) a deep ulceration and deformity of the oesophageal axis and (iii) any abnormal contact in CT, are considered to be very useful.

Introduction of high molecular weight (IgG) proteins into receptor coupled, permeabilized smooth muscle

The permeability to high molecular weight (IgG, 150 kD) proteins of the plasma membrane of receptor-coupled smooth muscles permeabilized with beta-escin was determined using confocal microscopy of immunofluorescent tracers and measurement of lactate dehydrogenase (LDH, 135-140 kD) leakage. Permeabilized strips of rabbit portal vein and guinea pig ileum were incubated in a relaxing solution containing mouse anti-smooth muscle alpha-actin antibody and immunostained with F(ab')2 labeled with tetramethyl rhodamine isothiocyanate. Confocal light microscopy of Triton X-100 and beta-escin permeabilized cells showed homogeneous staining of the cytoplasm, whereas in alpha-toxin treated and intact preparations only damaged cells at the edges of the strips were stained. Both the Ca(2+)-sensitizing effect of phenylephrine, in rabbit portal vein, and Ca2+ release by carbachol in guinea pig ileum, were retained after permeabilization and the treatment with the primary antibody. During the 30 min permeabilization, 38%, and within the next 75 min an additional approximately 30%, of the total LDH leaked out from the beta-escin-treated group, but not from the alpha-toxin-treated group (3.2%). The responsiveness to agonist and maximum contractility was improved if the preparations were incubated during the introduction of proteins at 4 degrees C, rather than 24 degrees C. Ca(2+)-independent myosin light chain kinase (61 kD) contracted the permeabilized portal vein in the absence of free Ca2+ (pCa < 8). In conclusion, permeabilization with beta-escin allows the transmembrane passage of 150 kD proteins under our experimental conditions that also retain receptor-coupled signal transduction.

Function of the NH2-terminal domain of the regulatory light chain on the regulation of smooth muscle myosin

The role of the NH2-terminal domain of the 20,000-dalton light chain on the regulatory function of smooth muscle myosin was studied by exchanging it in myosin with various mutant forms. The 10 S to 6 S conformational transition as well as the thick filament formation were significantly influenced by the deletion or substitution of the amino acid residues at the NH2-terminal side of the phosphorylation site (Ser19). Whereas the deletion of Ser1-Thr10 did not significantly affect these functions, further deletion of Lys11-Arg16 completely abolished the formation of 10 S conformation and induced thick filament formation. Among the residues in this region, Arg13 and Arg16 were most important for these functions since substitution of these residues by Glu or Ala significantly altered these functions. Similar substitutions of Lys11 and Lys12 also stabilized the 6 S conformation and thick filament formation but less effectively. While the 6 S conformation was stabilized, the deletion of NH2-terminal residues did not activate the actin-activated ATPase activity. This suggests that stabilization of the 6 S conformation is not directly coupled with activation of actomyosin ATPase activity but rather a more defined conformational change around the phosphorylation site is necessary for activation. Such a change also influences the 6 S to 10 S conformation and, therefore, the filament formation. To support this notion, substitution of Lys11 and Lys12 by Glu-Glu inhibited the phosphorylation-induced activation of actomyosin ATPase activity.

Structural requirement of the regulatory light chain of smooth muscle myosin as a substrate for myosin light chain kinase

The substrate structure required for skeletal and smooth muscle myosin light chain kinases (MLC kinase) was studied by using various mutant regulatory light chains of smooth muscle myosin. The deletion of the NH2-terminal 10 residues did not greatly affect the kinetic parameters of smooth MLC kinase; however, deletion of an additional 3 residues, Lys11-Arg13, prevented phosphorylation. In contrast, deletion of Lys11-Arg13 did not completely abolish the phosphorylation for skeletal MLC kinase, and deletion of three additional residues was required for complete inhibition. Substitution of Arg16 with Glu markedly decreased Vmax for both smooth and skeletal MLC kinases. Substitution of Lys11-Arg13 with acidic or noncharged residues decreased Vmax, but these changes were much lower than that occurring on substitution of Arg16. Replacement of Lys11-Arg13 with acidic residues reduced the affinity of the free LC20 but had little effect on the myosin-incorporated LC20. These results were different from those previously obtained with synthetic peptide analogs (Kemp, B. E., Pearson, R. B., and House, C. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 7471-7475) and suggest that a cluster of the basic amino acid residues are not fundamentally important for substrate recognition. The structural simulation revealed that the guanidyl group of Arg16 but not the corresponding Glu13 of skeletal light chain resides in close proximity to Ser19, suggesting that the guanidyl group of Arg16 stabilizes the phosphate transfer and that the introduction of Glu at the 16th position would significantly destabilized this reaction.

Laparoscopy-assisted surgery: a new technique for transhiatal esophageal dissection

Esophageal dissection under laparoscopic monitoring is performed during total esophagectomy to treat patients with cervical esophageal carcinoma. Using this technique, a safe esophageal dissection can be made from the surrounding mediastinal tissues. Some of the disadvantageous consequences of a blunt dissection, including the blind maneuver, may thus be prevented and various intraoperative and postoperative complications may be avoided.

Involvement of the C-terminal residues of the 20,000-dalton light chain of myosin on the regulation of smooth muscle actomyosin

The segment of smooth muscle regulatory light chain essential for the phosphorylation dependent activation of actomyosin motor activity and the binding of myosin heavy chain was identified. The C-terminal domain of the 20-kDa light chain, which is less conserved than the rest of the polypeptide among various muscle types, was mutated by either deletion or substitution of amino acid residues and the mutant light chains were then incorporated into myosin by subunit exchange. Deletion of Lys149-Ala166 markedly reduced the affinity of the light chain for the heavy chain, whereas the C-terminal five residues, Lys167-Asp171, did not contribute to the binding affinity. Deletion of Lys149-Phe158 abolished the phosphorylation-dependent activation of actomyosin ATPase activity as well as superprecipitation activity. These results suggest that the C-terminal domain of the regulatory light chain is critical for transmitting the change in the conformation of the regulatory light chain induced by phosphorylation at Ser19 to the heavy chain.

[A case of hepatocellular carcinoma whose lung metastases and tumor emboli in the inferior vena cava disappeared by oral administration of UFT]

A 65-year-old male with hepatocellular carcinoma was admitted to our hospital. Hepatic angiography showed a hypervascular tumor 8 cm in diameter in the right lobe of the liver with tumor emboli in the inferior vena cava and right atrium. Then, two chemoembolization treatments using gelform and cisplatin suspended in Lipiodol were performed. Although the size of the main tumor in the liver and tumor emboli was reduced, 6 months after the initial chemoembolization the serum levels of alfa-fetoprotein (AFP) and plasma des-gamma-carboxy prothrombin (DCP) rose to 14,000 ng/ml and 6.4 AU/ml, respectively, and multiple lung metastases were detected by CT scan. Then, 200 mg/day of UFT was administered orally. Four months after the administration, the levels of AFP and DCP markedly decreased to 95 ng/ml and 0.0 AU/ml, respectively, and the lung metastases and tumor emboli disappeared. Moreover, there were no side-effects including liver dysfunction.

A novel mechanism for the Ca(2+)-sensitizing effect of protein kinase C on vascular smooth muscle: inhibition of myosin light chain phosphatase

Mechanisms of Ca2+ sensitization of both myosin light chain (MLC) phosphorylation and force development by protein kinase C (PKC) were studied in permeabilized tonic smooth muscle obtained from the rabbit femoral artery. For comparison, the Ca2+ sensitizing effect of guanosine 5'-O-(gamma-thiotriphosphate) (GTP gamma S) was examined, which had been previously shown to inhibit MLC phosphatase in phasic vascular smooth muscle. We now report that PKC activators (phorbol esters, short chain synthetic diacylglycerols and a diacylglycerol kinase inhibitor) and GTP gamma S significantly increase both MLC phosphorylation and force development at constant [Ca2+]. Major phosphorylation site occurring in the presence of phorbol-12,13-dibutyrate (PDBu) or GTP gamma S at constant [Ca2+] is the same serine residue (Ser-19) as that phosphorylated by MLC kinase in response to increased Ca2+ concentrations. In an ATP- and Ca(2+)-free solution containing 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), to avoid the kinase activity, both PDBu and GTP gamma S significantly decreased the rate of MLC dephosphorylation to half its control value. However, PDBu inhibited the relaxation rate more than did GTP gamma S. In the presence of microcystin-LR to inhibit the phosphatase activity, neither PDBu nor GTP gamma S affected MLC phosphorylation and force development. These results indicate that PKC, like activation of GTP binding protein, increases Ca2+ sensitivity of both MLC phosphorylation and force production through inhibition of MLC phosphatase.

Comparison of the effects of 2,3-butanedione monoxime on force production, myosin light chain phosphorylation and chemical energy usage in intact and permeabilized smooth and skeletal muscles

The primary goal of this study was to determine the utility of 2,3-butanedione monoxime as a tool for determining and separating the chemical energy usage associated with force production from that of force-independent, or 'activation' processes in smooth and skeletal muscles. We determined the effects of 2,3-butanedione monoxime on force production, myosin light chain phosphorylation and high energy phosphate usage in intact and permeabilized smooth (rabbit taenia coli) and skeletal (mouse extensor digitorum longus) muscles. In the intact taenia coli, 2,3-butanedione monoxime depressed the tonic phase of the tetanus, contractures evoked by high potassium (90 mM) and by carbachol (10(-5) M) and the small force response evoked by these agonists after treatment with D-600 (10(-5) M). In the electrically stimulated intact taenia coli 2,3-butanedione monoxime (0-20 mM) caused a proportional inhibition of tetanic force output, myosin light chain phosphorylation and high energy phosphate usage (ED50 approximately 7 mM for all these parameters). At 20 mM 2,3-butanedione monoxime, force and energy usage fell to near zero and the degree of myosin light chain phosphorylation decreased to resting values, indicating a shut-down of both force-dependent and force-independent energy usage at high concentrations of 2,3-butanedione monoxime. In permeabilized taenia coli, 2,3-butanedione monoxime had little or no depressant effects on force production, ATPase activity or calcium sensitivity. 2,3-butanedione monoxime had a very modest inhibitory effect on the in vitro motility of unregulated actin filaments interacting with thiophosphorylated myosin. In solution, 2,3-butanedione monoxime inhibited myosin light chain kinase, but not the phosphatase (SMP-IV). These results suggest that the major effect of 2,3-butanedione monoxime is not on the contractile proteins themselves, but rather on calcium delivery during excitation, thereby reducing the degree of activation of myosin light chain kinase and subsequent activation of myosin by light chain phosphorylation. Thus, 2,3-butanedione monoxime is not useful for the determination of the energetics of activation processes in smooth muscle because of its inhibition of both force-dependent and force-independent processes. In contrast, in the intact mouse extensor digitorum longus, 2,3-butanedione monoxime inhibits tetanic force production (ED50 approximately 2 mM) to a much greater extent than myosin light chain phosphorylation. When 2,3-butanedione monoxime was used to manipulate force production in muscles at L(o), it was found that approximately 60% of the total energy usage was force-independent and the remainder was force-dependent.(ABSTRACT TRUNCATED AT 400 WORDS)

Gastric syphilis: case report and review of the literature

A 35-year-old Japanese woman consulted our clinic with a one-month history of epigastric pain. Although a superficial depressed type of early gastric carcinoma was highly suspected from the results of upper gastrointestinal barium studies and gastroscopy, there was no evidence of malignancy in the biopsy specimen. Gastric syphilis was then considered based on skin lesions and serological studies. Diagnostic antisyphilitic therapy improved the symptoms and gastric lesion promptly. A review of the recent reports indicated that most cases of early phase gastric syphilis seem to present morphologically either as a narrowing lesion or shallow ulcero-nodular lesion at the pyloric antrum. Therefore, whenever such findings are recognized either radiologically or gastroscopically and no malignant cells are found in biopsy specimens, gastric syphilis and diagnostic antisyphilitic therapy should be considered.

Immunohistochemical detection of CEA, CA19-9, and DF3 in esophageal carcinoma limited to the submucosal layer

The immunohistochemical expression of CEA, CA19-9, and DF3 was studied in 20 normal epithelia, 11 cases of dysplasia, 32 squamous cell carcinomas restricted within the submucosal layer (SM carcinoma), and 42 advanced squamous cell carcinomas of the esophagus. The modes of expression were grouped into three patterns, i.e., negative, focal, and diffuse patterns. No diffuse expression of CEA, CA19-9, or DF3 was found in the normal squamous epithelium and dysplasia. In the carcinomas (32 SM carcinomas and 42 advanced carcinomas) the diffuse expression of CEA and CA19-9 was found in four lesions, and only one of the four lesions was an SM carcinoma, while the diffuse expression of DF3 was found in 16 of the 32 SM carcinomas and 25 of the 42 advanced carcinomas. These results indicated that the diffuse expression of these tumor-associated antigens were characteristic of tumor tissue in the esophagus, and particularly DF3 was diffusely expressed earlier than CEA or CA19-9. The expression of DF3 in the esophagus may, therefore, be a marker of the early stage of tumor growth.

New isoforms of Ca2+/calmodulin-dependent protein kinase II in smooth muscle

Four novel isoforms of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) were found in rat aorta smooth muscle. Two of them were related to gamma-isoform of brain CaM kinase II (gamma-a). Differences in the primary structure of these isoforms were located in the variable region. One of them (gamma-b) contained 23 unique amino acid residues, whereas the other (gamma-c) did not contain this sequence. Both isoforms lacked the two segments (Val-316 to Gln-337 and Lys-353 to Leu-362) present in gamma-a. The DNA sequence of these gamma-isoforms except the variable region was exactly the same, suggesting that they are produced by alternative splicing. Another two isoforms were related to the delta-isoform of brain CaM kinase II (delta-a). delta-b contained a unique 11-residue sequence in the variable region whereas delta-c did not. As found for gamma-isoforms, the sequence analysis suggested that the three delta-isoforms are also produced by alternative splicing. Analysis of RNA by reverse transcription PCR confirmed the existence of specific messages for gamma-b, delta-a and delta-b. The variety of isoforms of CaM kinase II suggest that each isoform may play a specialized role in cell regulation.

Recent advances in the diagnosis and surgical treatment of patients with carcinoma of the esophagus

Five hundred and eighty-five patients with carcinoma of the thoracic esophagus underwent resection of the esophagus in the surgical department in which we work since 1965. The postoperative 30 day mortality rate was 11.9 percent during the early period, from 1965 to 1974, whereas it has decreased to 1.3 percent in the period since 1985. The most common cause of mortality was pulmonary complications (45.8 percent). The five year survival rate of patients who underwent a curative resection between 1975 and 1984 was only 29.1 percent, whereas it has remarkably increased to 49.9 percent since 1985, at which time cervical thoracic and abdominal lymph node dissection began to be regularly performed. There were three patients with intraepithelial carcinoma and 17 with mucosal carcinoma, respectively; none of these patients died within five years postoperatively. However, the five year survival rate of 73 patients with submucosal carcinoma of the esophagus was only 52.6 percent. Thus, it is clear that the prognosis substantially worsens when carcinomatous invasion reaches the submucosal layer. From the results of this study, it can be concluded that a combination of early detection and resection of the esophagus with three field lymph node dissection offers the best chance for long term survival in patients with carcinoma of the esophagus.

Okadaic acid induces marked shape change of human platelets

Okadaic acid (OA) induced marked shape changes of human platelets but neither granule secretion nor increase in [Ca2+]i occurred. Morphological changes induced by OA were unique and different from those observed with thrombin mainly in two respects. One is that the pseudopods formed by OA treatment were longer and straighter than those by thrombin. The other is that no granule centralization was observed with OA-treatment, although central condensation of cytofilaments was observed as was with thrombin. The immunocytochemical analysis employing anti-myosin antibody revealed that myosin was distributed in the elongated pseudopods. Since OA induced phosphorylation of the 20-kDa myosin light chain (MLC20) corresponding to the change in shape of platelets but did not induce phosphorylation of the 47-kDa protein (pleckstrin) (Higashihara M. et al. FEBS Lett. 307:206-210, 1992), these results suggest that phosphorylation of MLC20 plays an important role in OA-induced unique morphological changes of platelets.

Dipyridamole inhibits early wound healing in rat skin incisions

In an effort to investigate the significance of platelet aggregation on early wound healing, the inhibitory effects of an antiplatelet drug (dipyridamole) on tensile wound strength was assessed. The breaking strength of the dorsal incisional wounds in Donryu rats both with and without the administration of dipyridamole was measured. In experiment I, the intraperitoneal administration of dipyridamole (100 mg/kg/day, Group A; 50 mg/kg/day, Group B) and saline (3 ml/day; Group C) was performed during the periods between the day of incision and the excision of the healing wound specimen in a 2.0-cm width on the third and seventh postoperative days (POD). The wound breaking strength was 229 +/- 44, 256 +/- 39, and 352 +/- 38 g/cm2 on POD 3 and 477 +/- 67, 578 +/- 60, and 764 +/- 31.9 g/cm2 on POD 7, in Groups A, B, and C, respectively. In experiment II, we performed the intraperitoneal administration of either dipyridamole (100 mg/kg) or 3 ml of saline as a control just before incision (Group a) as well as at 4 hr (Group b), and 12 hr (Group c) after incision, and the percentages of tensile strength compared with the control were 72 +/- 8, 89 +/- 13, and 103 +/- 23% in Groups a, b, and c, respectively. The administration of dipyridamole significantly inhibited the wound healing and, therefore, platelet aggregation would appear to play an important role in the early phase of wound healing.

[Multidisciplinary preoperative treatment of esophageal cancer]

To obtain a better prognosis, multidisciplinary treatment is essential for esophageal cancer. We prescribed hyperthermia combined with irradiation and chemotherapy (HCR) preoperatively for patients with resectable esophageal squamous cell carcinoma. The local effect of the HCR therapy was better than that of chemotherapy and radiotherapy (CR), showing 19.3% of the complete response rate. The five-year survival rate of stage III and IV patients given preoperative HCR was 18.5%, compared with 10.4% in the CR therapy group and 10.5% in the preoperative no treatment group. Moreover, preoperative HCR therapy improved prognosis of cases with far advanced cancer which invades the neighboring organs, showing 20.1% of 3-year survival rate. To evaluate the effectiveness of hyperthermia more objectively, we started a prospective randomized trial from 1988, comparing HCR therapy and CR therapy. The local effect is better in HCR therapy. When treated with cisplatin, the rate of complete response (Grade 3) in HCR therapy was 35.3%, which is as high as for the multi-drug combined treatment reported from other institutes previously. More effective multidisciplinary treatment together with basic research are necessary for a better therapeutic outcome.

Correlation between high temperature dependence of smooth muscle myosin light chain phosphatase activity and muscle relaxation rate

Q10 values of the protein phosphatases that can dephosphorylate the regulatory light chain of smooth muscle myosin were determined. Six phosphatases were examined, i.e. skeletal muscle protein phosphatase 1c; protein phosphatase 2Ac; smooth muscle phosphatases (SMP) I, II, and IV; and myosin-associated protein phosphatase (MAP phosphatase). Among them, SMP-IV and MAP phosphatase, which can dephosphorylate intact smooth muscle myosin, showed extremely high Q10 values (5.3 and 5.2, respectively). On the other hand, the Q10 values of other tested phosphatases were within the range of the normal enzyme reaction (Q10 = 2.0). The rate of dephosphorylation of the myosin light chain in alpha-toxin-skinned strips was measured at different temperatures. The results provided a Q10 of 5.1, which was quite similar to those values obtained for SMP-IV and MAP phosphatase. These results suggest that the physiological myosin light chain phosphatases are SMP-IV and/or MAP phosphatase, i.e. type 1 protein phosphatases. The temperature dependence of maximum force, the steady-state extent of myosin light chain phosphorylation, and the relaxation rate of alpha-toxin-permeabilized rabbit portal vein smooth muscle strips were measured. Both maximum force and the extent of myosin light chain phosphorylation were significantly higher at lower temperature (15 degrees C) than at higher temperature (25 degrees C) under all pCa conditions tested, i.e. > 8, 6.3, and 5. The temperature dependence of the relaxation rate was much steeper (decreased 4 times by lowering the temperature from 25 to 15 degrees C) than that of the initial rate of increase in force development (decreased 1.4 times by lowering the temperature from 25 to 15 degrees C). These results are consistent with the Q10 values of myosin light chain phosphatases (Q10 = 5) and myosin light chain kinase (Q10 = 1.7) and further show that the smooth muscle type 1 phosphatases are responsible for the dephosphorylation of smooth muscle myosin in situ.

A novel myosin I from bovine adrenal gland

A 3.5 kb cDNA clone was isolated from bovine adrenal gland cDNA library. The clone contained a full-length 3.1 kb open reading frame, encoding a novel myosin I. The deduced amino acid sequence was highly homologous to other known myosin Is in the N-terminal 2 kb region which corresponds to the myosin head domain, while no strong homology was detected in the tail region. The head-tail junction contained the Ca(2+)-independent calmodulin binding consensus sequence, suggesting that the novel myosin I binds calmodulin. This was confirmed by calmodulin overlay which showed the binding of 125I-calmodulin to the recombinant myosin I expressed in E. coli. Northern blots with probes from head and tail regions of this myosin I revealed that this novel myosin I is widely distributed among various tissues.

Mutagenesis of the phosphorylation site (serine 19) of smooth muscle myosin regulatory light chain and its effects on the properties of myosin

A full-length cDNA of smooth muscle regulatory light chain was obtained and the recombinant regulatory light chain was expressed in an Escherichia coli expression system. The recombinant regulatory light chain was introduced into myosin or HMM using a subunit exchange strategy [Morita, J., Takashi, R., & Ikebe, M. (1991) Biochemistry 30, 9539-9545]. The recombinant wild-type regulatory light chain exhibited the same biological properties as the natural isolate, i.e., phosphorylation at Ser-19 by myosin light-chain kinase and phosphorylation-activated actomyosin ATPase activity. To clarify whether or not the activation of the ATPase by phosphorylation is simply due to the introduction of negative charge, we produced three mutant light chains. Two of them contain Ser-19 substituted by either Asp or Ala and the third contains Asp substituted for both Thr-18 and Ser-19. Incorporation of the Asp mutant partially activated actomyosin ATPase activity but the activation level was significantly lower than that by phosphorylation. The Asp/Asp mutant further activated actomyosin ATPase activity. On the other hand, the Ala mutant did not affect the ATPase activity. Incorporation of Asp mutant slightly affected the 10S-6S conformational transition and filament formation of myosin. The Asp/Asp mutant more significantly affected the 10S-6S conformational transition and filament formation of myosin. These results suggested that the activation of smooth muscle myosin requires the introduction of negative charge in the defined spacial position. Using Ser-19 deficient mutants, the effects of Thr-18 phosphorylation on myosin function was also studied. Actin-activated ATPase activity of myosin was significantly activated by phosphorylation of Thr-18.(ABSTRACT TRUNCATED AT 250 WORDS)

Cleavage at site A, Glu-642 to Ser-643, of the gizzard myosin heavy chain decreases affinity for actin

The actin-activated ATPase activities of subfragment 1 (S1) produced from gizzard myosin by papain or Staphylococcus aureus protease are different. The activity of the latter is lower, in spite of the presence of intact 20,000-dalton light chains. To study this difference, the S. aureus protease S1 was subjected to further proteolysis by papain. This second stage of proteolysis markedly increased actin-activated ATPase, due to a decrease in K(actin) with no change in Vm and increased the affinity of S1 for actin in the presence of ATP. Treatment with papain caused degradation of the 20-kDa light chain, a decrease in the 26-kDa C-terminal domain of S1 and the 68-kDa fragment containing the N-terminal and central domains, and in the appearance and progressive increase of a 94-kDa fragment. The increase in actin-activated ATPase activity was due to the production of the 94-kDa fragment but not due to light chain degradation. Analyses of N-terminal sequences following papain digestion showed that the 94-kDa fragment was formed from a combination of the 68- and 26-kDa fragments. The bond formed probably involved the N-terminal residue of the 26-kDa fragment (Ser-643) and a side chain carboxyl (Glu-642) or amine (Glu-636). From the sequence data site A was identified as Glu-642-Ser-643. These results confirm the importance of site A in actin-binding of gizzard myosin. It is suggested that the sequence Ser-643 and Val-659, as well as the 3 lysine residues, are important for actin binding.

Boundary of the autoinhibitory region of smooth muscle myosin light-chain kinase

It has been proposed that myosin light-chain kinase (MLCK) activity is inhibited in the absence of Ca2+/calmodulin by a pseudosubstrate sequence [Kemp, B. E., Pearson, R. B., Guerriero, V. J., Bagchi, I., & Means, A. R. (1987) J. Biol. Chem. 262, 2542-2548]. To evaluate this hypothesis, the role of a cluster of basic residues, Arg797-Arg798-Lys799, which are essential for the pseudosubstrate sequence, in the inhibition of MLCK was studied. A full-length cDNA of chicken gizzard MLCK was obtained, and the recombinant MLCK which contains the entire amino acid sequence was expressed in Escherichia coli. The Ca2+/calmodulin-dependent activity of the recombinant MLCK was comparable to that of the naturally isolated MLCK. Two truncation mutants, MT799 and MT796, were produced, of which MT799 but not MT796 contained a cluster of basic residues. Neither MT799 nor MT796 bound calmodulin, and kinase activity was inhibited (similar to MLCK activity in the absence of Ca2+/calmodulin). However, the kinase activity of the mutants was increased markedly by subsequent tryptic proteolysis. The tryptic digestion of the mutants initially produced a 64-kDa fragment then, subsequently, the 61-kDa fragment, and the increase in activity coincided with the appearance of the 61-kDa fragment. This was similar to the digestion profile of native MLCK, and it is known that the 61-kDa fragment is the constitutively active kinase [Ikebe, M., Stepinska, M., Kemp, B. E., Means, A. R., & Hartshorne, D. J. (1987) J. Biol. Chem. 262, 13828-13834].(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity labelling of smooth-muscle myosin light-chain kinase with 5'-[p-(fluorosulphonyl)benzoyl]adenosine

5'-(p-(Fluorosulphonyl)[14C]benzoyl)adenosine (FSBA) was synthesized and used as a probe to study the ATP-binding site of smooth-muscle myosin light-chain kinase (MLCK). FSBA modified both free MLCK and calmodulin/MLCK complex, resulting in inactivation of the kinase activity. Nearly complete protection of the calmodulin/MLCK complex against FSBA modification was obtained by addition of excess ATP whereas MLCK activity alone was lost in a dose-dependent manner even in the presence of excess ATP. These results suggest that FSBA modified ATP-binding sites and ATP-independent sites, and the latter sites are protected by calmodulin binding. The results also suggest that the ATP-binding site is accessible to the nucleotide substrate regardless of calmodulin binding. The FSBA-labelled MLCK was completely proteolysed by alpha-chymotrypsin, and the 14C-labelled peptides were isolated and sequenced. The sequence of the labelled peptide was Ala-Gly-X-Phe, where X is the labelled residue. The sequence was compared with the known MLCK sequence, and the labelled residue was identified as lysine-548, which is located downstream of the GXGXXG motif conserved among ATP-utilizing enzymes.

Operative procedures of reconstruction after resection of esophageal cancer and the postoperative quality of life

To investigate the influence of the operative procedures of reconstruction after resection of esophageal cancer on the postoperative quality of life, an interview was conducted and subjective and objective factors related to the quality of life were evaluated in 50 patients without a recurrence of esophageal cancer. Among the 50 cases, reconstruction by the antethoracal route was performed in 9 (group I) and by the retrosternal route in 24 (group II). Intrathoracic anastomosis was done in 17 (group III). A postoperative disturbance of the food passage was seen 22.0, 41.6, and 5.9% in groups I, II, and III, respectively. Dumping symptom was evident 11.1, 12.5, and 11.8%, respectively. Heartburn was seen only in two cases, in group III. A body weight loss of more than 1.0 kg from preoperative weight was seen in 33.3, 41.7, and 41.2% of groups I, II, and III, respectively. There was no difference in the postoperative performance status or laboratory data among the groups. Thus, although intrathoracic anastomosis was favorable for postoperative food passage, there was no significant difference in any other factors in the quality of life among the routes of reconstruction, and the quality of life gradually improved in patients of all groups as postoperative time passed in the cases without postoperative recurrence of esophageal cancer.

Observation of multiple myosin subfragment 1-ADP-fluoroberyllate complexes by 19F NMR spectroscopy

Fluoroaluminate and fluoroberyllate are potent inhibitors of the ATPase activity of myosin. Inhibition requires the presence of ADP, and much evidence has accumulated to suggest that the tetrahedral fluoroaluminate and fluoroberyllate ions act as phosphate analogues, binding with high affinity at the active site in the position normally occupied by the terminal phosphate of ATP. Both the S1-ADP-fluoroaluminate and the S1-ADP-fluoroberyllate species are thought to resemble kinetic intermediates in the actomyosin ATPase cycle. Characterization of S1-bound fluoroaluminate by 19F NMR is straightforward; a single resonance identified as AlF4- is observed easily [Maruta, S., Henry, G.D., Sykes, B.D., & Ikebe, M (1993) J. Biol. Chem. 268, 7093-7100]. Bound fluoroberyllate, by contrast, was found to give rise to four separate peaks: a downfield pair at -80 and -83.5 ppm and an upfield pair at -101.5 and -103 ppm, suggesting the existence of four distinct types of S1-ADP-fluoroberyllate complex. The relative intensities of the bound resonances can be altered by changing rhe F:Be ratio during complex formation. Integration of a spectrum acquired in the presence of a fluorine-labeled nucleotide derivative, 3'(2')-O-(4-fluorobenzoyl)-ADP, in place of ADP yielded a bound fluoride to nucleotide ratio of 1.7-1.9 to 1, showing that the major bound fluoroberyllate species cannot be BeF3- as is usually thought. It is proposed that the bound fluoroberyllates correspond to the neutral species BeF2(H2O)2 and BeFOH(H2O)2 and the negatively charged species [BeF2OH.H2O]- and [BeF3.H2O]-, although other possibilities are discussed.