A method for selective isolation of the amino-terminal peptide from alpha-amino-blocked proteins

A method for selective isolation of the amino N-terminal peptide from an alpha-amino (N alpha)-blocked protein is presented. The method consists of four steps. First, epsilon-amino groups of lysine residues in the protein are succinylated. Second, the derivatized protein is digested by either enzymatic or chemical cleavage. Third, the digest is subjected to reaction with cyanogen bromide-activated Sepharose. Only the N-terminal-blocked peptide fails to react, while the other peptides are covalently bound to the Sepharose. Fourth, uncoupled peptides are purified by reversed-phase chromatography. The amino acid sequence of the peptide including the blocking group can be determined by mass spectrometry. These procedures were successfully tested with three known N alpha-blocked proteins including bovine brain S100 protein, horse cytochrome c, and ovalbumin.

Drug discovery, development and deployment: a report from the 28th Joint Conference of the U.S.-Japan Parasitic Diseases Panels, Baltimore, Maryland, July 1993

The 28th Joint Conference of the Parasitic Diseases Panels of the U.S.-Japan Cooperative Medical Sciences Program held in Baltimore, Maryland focused on current research within both countries on antiparasitic chemotherapy. This meeting report summarizes presentations of work in progress on antiparasitic drugs currently in use and drugs under development or in clinical trials, as well as reports on potentially unique parasite characteristics that may provide targets for development of future therapeutics.

Amyloid beta-protein precursor-rich platelet microparticles in thrombotic disease

We investigated the association of amyloid beta-protein precursor (APP) and platelet derived microparticles in 20 normal controls and 91 patients with various diseases causing a thrombotic tendency. Compared with the controls, the mean percentage of APP-positive microparticles was significantly greater in the patients with cerebral infarction (39.1 +/- 17.7%, p < 0.001), diabetes (31.1 +/- 12.6%, p < 0.001), and uremia (30.1 +/- 14.7%, p < 0.01), but not in those with hypertension (8.2 +/- 6.3%, p = NS). Sixteen patients with cerebral infarction, 20 with diabetes, and 11 with uremia had microparticles with very high APP levels. In normal controls, 7.2 +/- 3.7% of the microparticles were positive for P-selectin, while the percentage in cerebral infarction, diabetes, uremia, and hypertension was respectively 43.5 +/- 15.1%, 40.0 +/- 12.8%, 31.8 +/- 12.2%, and 11.6 +/- 7.3%. There was a significant correlation between P-selectin and APP positivity of microparticles. Our results suggest that microparticle APP may have a regulatory influence on coagulation abnormalities.

Rebamipide, a novel antiulcer agent, attenuates Helicobacter pylori induced gastric mucosal cell injury associated with neutrophil derived oxidants

The effect of rebamipide, a novel antiulcer compound, on Helicobacter pylori activated neutrophil dependent in vitro gastric epithelial cell injury was investigated. Luminol dependent chemiluminescence (ChL), which detects toxic oxidants from neutrophils exhibited a 12-fold increase when the bacterial suspension of H pylori was added to the isolated human neutrophils. This change was significantly attenuated by rebamipide at a concentration less than 1 mM, showing that rebamipide may inhibit oxidant production from H pylori elicited neutrophils. To assess whether rebamipide attenuates gastric mucosal injury, we tested its inhibitory action on H pylori induced gastric mucosal damage associated with neutrophils in vitro. Rabbit gastric mucosal cells were monolayered in culture wells and coincubated with human neutrophils and H pylori, and the cytotoxicity index was then calculated. Cultured gastric cells were significantly damaged when they were incubated with human neutrophils activated by H pylori. This cellular damage was attenuated by rebamipide in a dose-dependent manner. Furthermore, spectrophotometrical measurement showed that rebamipide (1 mM) inhibits urease activity by 21.7%. As monochloramine (an oxidant yielded by reaction of neutrophil derived chlorinated oxidant and ammonia) is proposed as an important toxic molecule in this model, the current findings suggest that the preventive effect of rebamipide on H pylori elicited neutrophil induced gastric mucosal injury may result from its inhibitory actions on the neutrophilic oxidative burst as well as H pylori derived urease activity.

A clean-up method for analysis of trace amounts of microcystins in lake water

A clean-up method using high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) was developed to pursue trace amounts of microcystins in lake water. The method consisted of the combined usage of octadecyl silanized (ODS) silica gel and silica gel cartridges. In the first clean-up process, the retention behavior of microcystin RR on ODS silica gel cartridge was carefully observed together with microcystin LR, and 10% water-methanol was chosen as the best solvent system to elute microcystins from the ODS silica gel cartridge. Because many impurities still remained in the desired fraction from the raw water even after the clean-up with ODS silica gel, an additional clean-up process was developed using various cartridges. As a result of extensive experiments, the second clean-up process using silica gel cartridge was established, and the impurities were effectively eliminated. The present method including a tandem cartridge system allowed a precise analysis of microcystins in water samples from three different lakes at a 0.02 ppb level.

Voltage-activated K channel in luminal membrane of marginal cells of stria vascularis dissected from guinea pig

Inward rectifying K channel activity was observed in the luminal membrane of the marginal cell by use of the patch clamp technique. When pipette solution contained 150 mM KCl, the current reversed at 10.2 +/- 8.8 mV (N = 27). The channel current showed multiple subconductance levels and depolarization activated the channel very slowly (order of seconds). Current-voltage relationships in cell-attached mode showed inward rectification. The calculated slope conductance of inward and outward currents were 18 +/- 7 pS and 5.4 +/- 2.0 pS (N = 27), respectively. When pipette solution contained 75 mM NaCl and 75 mM KCl, the current reversed -7.0 +/- 7.6 mV (N = 6). When pipette solution contained NaCl or Na gluconate, the channel currents were outwardly directed within a range of -60 to 60 mV. These results suggested that the channel is selective to K+. The channel showed immediate run down after excision, and this rundown was not prevented by elimination of cytoplasmic Ca2+. The channel activity was not affected by an increase of intracellular cAMP and cGMP, an application of cytoplasmic catalytic subunit of PKA with ATP. Taking its density into consideration, the channel seems to contribute considerably to the K+ conductance of the luminal membrane of the marginal cell.

A mass spectrometric study on the in vivo posttranslational modification of GAP-43

GAP-43 isolated from calf brain was analyzed by the electrospray mass spectrometry. The mass spectrum of the intact protein showed two species with a mass difference of 80 Da, suggesting that the isolated GAP-43 contains phosphorylated species. To establish the in vivo phosphorylation sites, the protein was digested with trypsin, and analyzed by the liquid chromatography/mass spectrometry technique, in which a capillary reversed-phase chromatography column was connected on line to an electrospray mass spectrometer. Two pairs of peptides with a mass difference of 80 Da were observed. From the tandem mass spectrometry, two novel phosphorylation sites (Thr-87 and Ser-152) were identified. The novel phosphorylation sites contain proline immediately after the phosphorylated serines. No phosphorylated peptide was detected corresponding to the protein kinase C or casein kinase II phosphorylation sites. A peptide corresponding to the acetylated N-terminal peptide was also identified. The mass of the peptide suggests that the 2 cysteinyl residues are not palmitoylated but form a disulfide bridge.

Observation study on natural walking in the Tokyo metropolitan

In this study, data on walking speed, step numbers, cadence of natural walking were collected and their relations to foot wear, clothing, luggage carried and time of the day as well as crowdedness were investigated. This survey was held in Shinjuku, Tokyo in 1991. Six thousand three hundred and seventy nine walking people were observed from 10:00 am to 5:00 pm. Ten students who were trained to observe the walking were employed for the data collection. The observed subjects were divided into three age groups, namely young (less than 30 years), middle (31-60 years) and elder (over 61 years), and their age groups were decided by the students based on their appearance. For the analysis, they were further classified into male and female groups. The factors which affect walking speed, step number and cadence were taken into consideration. It was found that young people were more sensitive to their factors in their natural walking and old people showed lower flexibility to these factors.

O,O,S-trimethyl phosphorothioate increases Ca2+ independent nitric oxide synthase activity in the lung but decreases Ca2+/calmodulin dependent type in the cerebellum in Fischer 344 rats

In the present study, we investigated the possible role of nitric oxide synthase in lung injury using female Fischer 344 rats as a model animal and O,O,S-trimethyl phosphorothioate as an example of lung toxicants. One form of nitric oxide synthase, Ca2+/calmodulin dependent type, decreased monotonously in a dose-dependent manner in the cerebellum. In contrast, O,O,S-trimethyl phosphorothioate increased activities of Ca2+ independent nitric oxide synthase in the lung in a dose-associated manner from 5 mg/kg to 15 mg/kg, but decreased at 30 mg/kg. Lung toxicity of O,O,S-trimethyl phosphorothioate, however, as judged both by functional impairments (PaCO2 and [HCO3-]) and histopathological changes, increased sharply at 30 mg/kg. We thus tested the hypothesis that a potent nitric oxide synthase inhibitor, NG-nitro-L-arginine-methyl ester, may modify lung injury induced by O,O,S-trimethyl phosphorothioate. Treatment with NG-nitro-L-arginine-methyl ester at 20 mg/kg/day aggravated lung injury induced by O,O,S-trimethyl phosphorothioate: Pulmonary oedema and bleeding occurred, leading to an increase in mortalities at 15 mg/kg of O,O,S-trimethyl phosphorothioate, at which level it did not induce such changes as when dosed alone. These findings indicate that nitric oxide synthase in the lung might play a protective role in lung injury.

[A case of pulmonary alveolar proteinosis with elevated serum angiotensin-converting enzyme activity]

A 45-year-old man with diffuse infiltrates on the chest X-ray film was admitted to the hospital. At first, sarcoidosis was suspected due to the elevated serum angiotensin-converting enzyme (ACE) activity. Transbronchial lung biopsy and bronchoalveolar lavage, however, did not lead to that diagnosis. Pulmonary alveolar proteinosis (PAP) was diagnosed after an open lung biopsy. The diffuse infiltrates on his chest X-ray film diminished spontaneously. Two years later, diffuse infiltrates increased again with an elevated serum ACE activity. In this case, it seemed that the severity of PAP was associated with serum ACE activity. We review the literature on the relationship between serum ACE activity and dysfunction of alveolar macrophages in PAP.

Changes in vessel pressure and interstitial fluid pressure of normal subcutis and subcutaneous tumor in rats due to angiotensin II

To elucidate the mechanism of enhancement of transport of anticancer drugs into tumor tissue due to angiotensin II (AII), changes in microvascular pressure (MVP) and interstitial fluid pressure (IFP) due to AII were measured in normal subcutis and subcutaneous tumor in rats. Two different tumor cell lines AH109A and AH272 were used. MVP and IFP were measured using a microocclusion method and a diffusion chamber method, respectively. Insignificant changes in the pressure of normal venous vessels and the IFP of normal subcutis were brought about by AII-induced hypertension. In both AH109A and AH272, the IFP of the same region within the tumor increased with enlargement of tumor volume. The IFP of AH109A tumor (tumor volume = 1.8-2.2 cm3) increased slightly due to AII, but the tumor MVP of AH109A and AH272 increased markedly. Though both tumor IFP and MVP increased significantly due to AII, the increases the hydrostatic pressure difference between tumor vascular and interstitial spaces and leads to enhancement of the efficiency of filtration from tumor vessels to tumor tissue, which is one of the mechanisms of enhancement of drug delivery to tumor tissue due to AII.

Directional excitability of the utricle: a study by thermoconvective stimulation

The frog utricular macula was stimulated by thermoconvective flow in four different directions. The evoked utricular nerve action potentials were recorded via a glass suction electrode. The maximum spikes and the time constants of the potentials were counted. The spike counts and the time constants were not significantly different among stimuli. This suggests that the utricle has the same physiological excitability to any directional stimulus.

[Mechanism of hypoxemia after methacholine challenge]

Hypoxemia after the treatment of asthmatic attack continues for a while, and can even become worse after the treatment. This hypoxemia has been attributed to inhomogeneity of ventilation-to-perfusion ratios in the lungs of asthmatic patients. We studied post-hyperventilation hypoxemia in subjects with hypoxemia after a methacholine challenge test. Nineteen subjects who were hyperresponsive and hypoxemic after a methacholine challenge were studied. The methacholine challenge with incremental doses was stopped when the respiratory resistance doubled. Thereafter, oxygen and carbon dioxide concentrations in the expired air, mouth flow (VE), and oxygen saturation (using a pulse oximeter, SpO2) were monitored continuously. End-tidal PCO2 (PETCO2) as well as respiratory exchange ratio (R) were thus obtained. In 14 subjects, VE significantly increased from 8.6 +/- 1.2 (mean +/- SD) to 13.4 +/- 2.6 l/min and then decreased gradually, while PETCO2 significantly decreased from 38.5 +/- 2.3 to 29.1 +/- 4.4 Torr and then increased gradually, SpO2 decreased from 97 +/- 1.3 to 89 +/- 2.4% concomitant with a significant decrease in R from 0.86 +/- 0.04 to 0.67 +/- 0.05. In contrast, in 5 subjects VE significantly increased from 7.5 +/- 2.8 to 12.4 +/- 1.6 l/min and then remained unchanged, while PETCO2 significantly decreased from 37.9 +/- 1.3 to 31.3 +/- 3.9 Torr and then remained unchanged, SpO2 decreased from 98 +/- 1.1 to 92 +/- 1.9% with no change in R (from 0.84 +/- 0.06 to 0.87 +/- 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Enzymatic and genetic adaptation of soleus muscle mitochondria to physical training in rats

To evaluate the effects of physical training on mitochondrial gene expression and mitochondrial biogenesis in slow-twitch muscle, adult female Sprague-Dawley rats were trained for 3, 6, and 12 wk by running on a motor-driven treadmill (speed of 25 m/min and duration of 90 min/day, 5 days/wk), and the activities of citrate synthase, ubiquinol-cytochrome-c oxidoreductase, cytochrome oxidase, mitochondrial cytochrome b mRNA (by Northern blot analysis), and mitochondrial DNA (by slot-blot and Southern blot analyses) were measured in rat soleus muscle. A DNA probe for detection of mitochondrial mRNA and DNA was prepared from a 1,500-bp fragment of human mitochondrial DNA that included the coding region of the cytochrome b gene. Training for 3, 6, and 12 wk significantly increased the activities of citrate synthase (31, 28, and 47%, respectively), ubiquinol-cytochrome-c oxidoreductase (61, 63, and 77%, respectively), and cytochrome oxidase (25, 26, and 32%, respectively) in muscle. The concentration of cytochrome b mRNA in the muscle was proportionally elevated with the enzyme activities. On the other hand, the mitochondrial DNA concentration in the muscle was not altered by training for 3 or 6 wk but increased significantly after training for 12 wk (35% in the slot-blot analysis and 31% in the Southern blot analysis). These results suggest that an increase in the oxidative capacity of slow-twitch muscle by the relatively short-term training is regulated at the pretranslational step in mitochondrial protein synthesis but that the increase by the long-term training involves mitochondrial replication.

[A case of left main coronary artery stenosis: additional insertion of saphenous vein graft to discontinue cardiopulmonary bypass]

A 62-year-old man with the lesions of the left main coronary artery and all the three vessels underwent a complete revascularization, in which the left internal mammary artery (IMA) was anastomosed to the large LAD. Although the operation proceeded uneventfully, the patient could not be weaned from the cardiopulmonary bypass (CPB). Another saphenous vein graft insertion into the LAD just distal to the IMA made it possible to discontinue the CPB. Postoperative angiogram revealed the patency of all grafts. But the IMA graft showed flow competition and string sign. We assume that failure to wean the patient from the CPB might be caused by hypoperfusion of the IMA graft, and in such a case, insertion of a saphenous vein graft is effective.

The affinity of bopindolol and its two metabolites for a beta 2-adrenoceptor in the bovine mesenteric artery

Bopindolol and its two metabolites (18-502 and 20-785) were examined for their affinity to a beta 2-adrenoceptor in the bovine mesenteric artery using the radioligand binding assay method with [3H]CGP12177 as a radioligand. The Scatchard analysis of the data demonstrated a uniphasic plot with Kd and Bmax values of 0.86 +/- 0.16 nM, and 13.34 +/- 1.11 fmol/mg protein, respectively. The pKi values of bopindolol and its two metabolites for beta 2-adrenoceptors in the bovine mesenteric artery were 7.70 +/- 0.13, 8.07 +/- 0.13, 8.20 +/- 0.24, respectively, with 20-785 showing the highest values among these drugs. The present findings indicate that the bovine mesenteric artery membrane is predominantly beta 2-adrenoceptor tissue, and that bopindolol and its two metabolites were potent for beta 2-adrenoceptors in the bovine mesenteric artery.

Stereochemical basis of DNA recognition by Zn fingers

DNA-recognition rules for Zn fingers are discussed in terms of crystal structures. The rules can explain the DNA-binding characteristics of a number of Zn finger proteins for which there are no crystal structures. The rules have two parts: chemical rules, which list the possible pairings between the 4 DNA bases and the 20 amino acid residues, and stereochemical rules, which describe the specific base positions contacted by several amino acid positions in the Zn finger. It is discussed that to maintain the correct binding geometry, in which the N-terminus of the recognition helix is closer to the DNA than the C-terminus, the residues facing the DNA on the helix must be larger near the C-terminus, and that two different types of fingers (A and B) bind to DNA in distinctly different ways and cover different numbers of base pairs.

Sphingosine inhibits the synthesis of RNA primers by primase in vitro

We have previously shown the presence of sphingomyelin and sphingomyelinase in cell nuclei, suggesting that they may play a role in the intranuclear production of sphingosine, a potent bioactive molecule modulating diverse cellular functions. In the present study, the direct effects of sphingosine (C18:1) on the activity of DNA replication/repair polymerases were studied in vitro. Sphingosine had no effect on DNA polymerases alpha and beta and slightly inhibited DNA polymerases gamma, delta, and epsilon. In contrast, sphingosine strongly inhibited the activity of primase in a dose-dependent manner. On the other hand, dihydrosphingosine (C18:0), glycolipids, sphingomyelin, and ceramide had no effect on primase activity. Sphingosine equally inhibited the activity of primase complexed with DNA polymerase alpha, as well as its free form, with a Ki value of 4 microM. A gel-retardation analysis showed that the binding of primase with 32P-labeled template DNA was suppressed by sphingosine. Inhibition by sphingosine was competitive with the DNA template, but not with the substrate NTPs. After product analysis, a dose-dependent decrease in the amount of RNA primer products, consisting mainly of 10- and 11-mers, was observed in the presence of sphingosine, indicating that it inhibits the synthesis of RNA primers by primase. Sphingosine, however, had no effect on T7 RNA polymerase.