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Biomedical subjects

A Maeda

Publications and source records attributed to A Maeda.

At least 217 records · Page 12Linked to original sources

[Administration and dosage of fluorouracil (5-FU) continuous i.v. infusion in patients with non-curative resected/non-resected gastric cancer].

This study was conducted to establish the optimum postoperative adjuvant chemotherapy with 5-FU in patients with gastric cancer. Seventy gastric cancer patients were treated after surgery with one of the following regimens; 5-FU 10 mg/kg/24 hrs c.i.v. x 24 days (arm A, n = 25); 5-FU 20 mg/kg/24 hrs c.i.v. x 4 days/w x 3 courses (arm B, n = 16); 5-FU 30 mg/kg/24 hrs c.i.v. x 2 days/w x 4 courses (arm C, n = 25). Blood 5-FU concentration, adverse effects and prognosis in each arm were compared. Changes in blood 5-FU concentrations were dose-related. The three-year survival rates in arms A, B and C were 15.0, 13.5 and 0.0%, respectively; they tended to be greater in arms A and B, but differences were not statistically significant. The most frequent adverse effects of the treatments were gastrointestinal, such as stomatitis. The incidence of reactions tended to be low in arm C, i.e., high-dose intermittent administration. Arm B (4 days-on, 3 days-off) was modified to 4 days-on, 6 days-off (arm B'), because severe stomatitis developed. The severity and incidence of stomatitis were reduced in the modified arm B group. We believe that intensive postoperative adjuvant chemotherapy for patients with gastric cancer should be designed using the arm B' approach.

Adult↗

[The effect of preoperative oral fluid intake on the volume and pH of gastric contents in elective surgical patients--a comparison of tea with apple juice].

This study aimed to investigate the effect of 150 ml of either tea or apple juice on the volume and pH of gastric contents in 40 elective surgical patients, ranging in age from 18 to 70 years. They were given diazepam 5 approximately 10 mg and roxatidine 75 mg orally 2 hours before the start of isoflurane anesthesia or modified neuroleptic anesthesia. Immediately following the induction of anesthesia with thiopental and vecuronium, a nasogastric tube was placed to aspirate the gastric content to measure its volume and pH. The volume and pH of gastric contents were 6.4 +/- 8.5 ml, 6.0 +/- 2.2 in tea group and 17.1 +/- 18.4 ml, 4.4 +/- 2.6 in apple juice group, respectively. There was a significant difference in the gastric volume between the two groups (P < 0.05), while no significant difference in gastric pH was observed. This result suggests that apple juice is not appropriate as preoperative drink because apple juice increases gastric contents, and may cause aspiration pneumonia.

Adolescent↗

[The volume and pH of gastric fluid in elective surgical patients after preoperative oral fluid intake].

The effect of preoperative oral fluid intake on the volume and pH of gastric fluid was examined in 45 elective surgical patients ranged in ages from 18 to 70 years. Two hours preoperatively they all received oral roxatidine 75 mg with 10 ml water, immediately followed by 150 ml oral water or 150 ml refreshing drink or no fluid as control. Just after the induction of anesthesia, a Salem-sump tube was put down to the stomach to collect gastric fluid in each patient. The volume and pH of gastric fluid taken were 10.9 +/- 7.9 ml, 16.3 +/- 2.3 in control group, 8.0 +/- 6.0 ml, 6.2 +/- 2.4 in the water group and 6.3 +/- 6.0 ml, 7.1 +/- 1.7 in the refreshing drink group. As there were no significant differences in gastric pH values in the three groups, the highest value was found in the refreshing drink group. No significant difference in VAS of hungry and thirsty feeling was found among the three groups. We conclude that preoperative oral water or refreshing drink with roxatidine 75 mg 2 hours before the start of anesthesia may not increase the risk of aspiration during the induction of anesthesia.

Adolescent↗

Increased expression of tumor necrosis factor-alpha, interleukin-6, platelet-derived growth factor-B and granulocyte-macrophage colony-stimulating factor mRNA in cells of bronchoalveolar lavage fluids from patients with sarcoidosis.

Cytokines released from activated alveolar macrophages and T-lymphocytes affect the accumulation of monocyte-macrophage-lineage cells and therefore play an important role in the formation of sarcoid granuloma. Although it is likely that certain monokines and lymphokines are involved in the development of sarcoid granulomas, the evidence for this is not unequivocal. In an attempt to clear critical cytokines in the development and maintenance of sarcoid granuloma, we have measured the level of seven cytokine mRNA (TNF-alpha, IL-6, IL-8, TGF-beta, PDGF-B, IFN-gamma, and GM-CSF) in cells obtained by BAL from sarcoidosis patients and normal subjects. To detect cytokine mRNA, we employed a reverse transcription-polymerase chain reaction. We report that the levels of TNF-alpha, IL-6, PDGF-B and GM-CSF mRNA were significantly increased in BAL cells from the patients with pulmonary sarcoidosis compared to controls. No significant differences were observed in the mRNA expression of IL-8, TGF-beta and IFN-gamma. A significant correlation of the expression of the mRNA levels of seven cytokines in the same patients with sarcoidosis was observed between IL-8 and TNF-alpha, PDGF-B, and IL-6, IL-8 and IL-6 and TFN-alpha and PDGF-B and IL-8. This finding indicates that at least these four cytokines are involved in the cytokine network at the local alveolar site of chronic granulomatous inflammation. This study adds a report to the literature that supports a role for cytokine, TNF-alpha, IL-6, PDGF and GM-CSF in particular, in the promotion and maintenance of sarcoid granulomatous inflammation.

Adult↗

[Development of a functional fitness test for the elderly].

A test of functional fitness defined as physical capacity to independently perform daily functional activities was developed for aged persons. The functional fitness test was composed of four physical capacity evaluation tasks representing physical abilities necessary to perform main activities of daily living; viz. sitting and standing up test, zig-zag walking test, hand working test with pegboard for dexterity evaluation, and rope working test for self-care evaluation. The reliability and feasibility of the test were examined with 765 aged persons living in the community. The distribution of measurement values in each item showed neither extreme skewness nor kurtosis. Retest reliabilities for each task were 0.857 to 0.942, but the second trial showed significantly reduced (p < 0.001) values than the first trial in test-retest. Significant relationships (r = 0.503 to 0.627) between measurement values in each items and chronological age were found in both male and female. Functional fitness test and physical fitness test scores were correlated 0.740. These results showed that the functional fitness test developed in the present study has a high reliability and feasibility to evaluate functional capacity of daily living in aged persons.

Activities of Daily Living↗

Structural changes in the lumirhodopsin-to-metarhodopsin I conversion of air-dried bovine rhodopsin.

Structural changes during the photochemical reactions of unhydrated air-dried films of bovine rhodopsin in rod outer segments were examined by visible and Fourier transform infrared (FTIR) spectroscopy at 200, 240, and 280 K. These films exhibited conversion from a lumirhodopsin state to a metarhodopsin I state with a time constant of 13.5 min at 280 K, but did not form metarhodopsin II at all, as observed earlier for digitonin-extracted rhodopsin in dry gelatin films [Wald, Durell, and St. George (1950) Science 111, 179-181]. Lumirhodopsin which was stable in the dry film was very similar to normal lumirhodopsin. The metarhodopsin I-like state retained properties characteristic of lumirhodopsin in regard to a twisted structure between the C14-H and the Schiff base of the chromophore, and perturbation around Glu122, although the C-C stretch frequencies of the chromophore were identical with those of metarhodopsin I. Thus, under dry conditions some of the structural changes that lead to metarhodopsin I are partially inhibited. These defects could result in stable lumirhodopsin and the failure to form metarhodopsin II, which is in equilibrium with metarhodopsin I.

Animals↗

Glutamic acid 204 is the terminal proton release group at the extracellular surface of bacteriorhodopsin.

We have measured proton release into the medium after proton transfer from the retinal Schiff base to Asp85 in the photocycle and the C = O stretch bands of carboxylic acids in wild type bacteriorhodopsin and the E204Q and E204D mutants. In E204Q, but not in E204D, the normal proton release is absent. Consistent with this, a negative band in the Fourier transform infrared difference spectra at 1700 cm-1 in the wild type, which we now attribute to depletion of the protonated E204, is also absent in E204Q. In E204D, this band is shifted to 1714 cm-1, as expected from the higher frequency for a protonated aspartic than for a glutamic acid. Consistent with their origin from protonated carboxyls, the depletion bands in the wild type and E204D shift in D2O to 1690 and 1703 cm-1, respectively. In the protein structure, Glu204 seems to be connected to the Schiff base region by a chain of hydrogen-bonded water. As with other residues closer to the Schiff base, replacement of Glu204 with glutamine changes the O-H stretch frequency of the bound water molecule near Asp85 that undergoes hydrogen-bonding change in the photocycle. The results therefore identify Glu204 as XH, the earlier postulated residue that is the source of the released proton during the transport, and suggest that its deprotonation is triggered by the protonation of Asp85 through a network that contains water dipoles.

Aspartic Acid↗

Light-driven chloride ion transport by halorhodopsin from Natronobacterium pharaonis. 1. The photochemical cycle.

The photochemical cycle of the light-driven chloride pump, halorhodopsin from N. pharaonis, is described by transient optical multichannel and single-wavelength spectroscopy in the visible, and in the infrared. Titration of a blue-shift of the absorption maximum upon addition of chloride describes a binding site with a KD of 1 mM. The reaction sequence after the all-trans to 13-cis photoisomerization of the retinal in this chloride binding form is itself dependent on chloride. At 2 M chloride it is described by the scheme: HR-->K<==>L<==>N-->HR that relaxes in a few milliseconds, and is very similar to the photocycle of bacteriorhodopsin under conditions where the retinal Schiff base cannot deprotonate. At lower chloride concentrations, e.g., 0.1 M, however, a red-shifted state termed O appears between N and HR, in equilibrium with N. The absorption spectra of K, L, N, and O are very similar to their counterparts in the bacteriorhodopsin photocycle. As in their equivalents in bacteriorhodopsin, in the N state the retinal is still 13-cis, but it is reisomerized in the O state to all-trans.

Archaea↗

FTIR spectroscopy reveals microscopic structural changes of the protein around the rhodopsin chromophore upon photoisomerization.

Fourier transform infrared spectroscopy was used to investigate the local structure around the chromophore of rhodopsin and its change upon photoisomerization. A hydrated film of bovine rod outer segments was cooled at 80 K, and difference infrared spectra were obtained between bathorhodopsin and rhodopsin or between bathorhodopsin and isorhodopsin under suitable irradiation conditions. The spectra in a higher-frequency region (4000-1800 cm-1) revealed protein structural change by probing the O-H, N-H, and S-H stretching vibrational modes. The structural change of bound water molecules occurred upon formation of bathorhodopsin, where three water O-H increased the strength of their H-bonding. The water structure is identical in rhodopsin and isorhodopsin. These results suggest that the protein in the close proximity of the Schiff base of the chromophore is perturbed upon photoisomerization and causes rearrangement of the water molecules in bathorhodopsin. Upon the isomerization, the 3463 cm-1 band of the 11-cis form (rhodopsin) shifts to 3487 cm-1 for the all-trans form (bathorhodopsin) or to 3481 cm-1 for the 9-cis form (isorhodopsin). An N-H bond, possibly of an indole of tryptophan residue, is responsible for these bands. It is present in a hydrophobic environment around the beta-ionone ring and/or polyene chain of the retinal, and changes its geometrical alignment depending on the isomeric state. It is the only band distinct in frequency between rhodopsin and isorhodopsin in the high-frequency region, suggesting that the specific interaction between the N-H and the chromophore contributes to the more efficient isomerization in rhodopsin than isorhodopsin. The stretching vibrations of the water O-H, cysteine S-H, and amide N-H of the peptide backbone decrease in frequency upon formation of bathorhodopsin, indicating that H-bonding around the chromophore becomes stronger in bathorhodopsin. This shows that at least a part of the energy absorbed in the chromophore is already transferred to the protein in bathorhodopsin by strengthened H-bonding. The chromophore-protein interaction as a suitable reaction field in rhodopsin is discussed on the basis of these observations.

Amino Acid Sequence↗

Endothelin induced collagen remodeling in experimental pulmonary hypertension.

To investigate pathophysiological roles of endothelin-1 (ET-1) in collagen remodeling in pulmonary hypertension, we measured: (a) mRNA expression, concentration, localization of ET-1; (b) changes in types and content of collagen in the lung; (c) and confirmed direct effects of ET-1 on type V collagen metabolism in vascular smooth muscle cells. Monocrotaline-treated rats showed pulmonary hypertension with medial hypertrophy and perivascular fibrosis of pulmonary arteries. At the progressive stage of pulmonary hypertension, both ET-1 levels and its mRNA expression in the lung increased. Total collagen in the lung rose markedly with a higher rate of increase in type V collagen. ET-1, which exists in vascular smooth muscle cells, other perivascular cells and endothelium, stimulated type V collagen production. Our results suggest that local production of ET-1 in the lung contributes to progression of pulmonary hypertension through changes in phenotypes and content of collagen.

Animals↗

The complex extracellular domain regulates the deprotonation and reprotonation of the retinal Schiff base during the bacteriorhodopsin photocycle.

During the L-->M reaction of the bacteriorhodopsin photocycle the proton of the retinal Schiff base is transferred to the anionic D85. This step, together with the subsequent reprotonation of the Schiff base from D96 in the M-->N reaction, results in the translocation of a proton across the membrane. The first of these critical proton transfers occurs in an extended hydrogen-bonded complex containing two negatively charged residues (D85 and D212), two positively charged groups (the Schiff base and R82), and coordinated water. We simplified this region by replacing D212 and R82 with neutral residues, leaving only the proton donor and acceptor as charged groups. The D212N/R82Q mutant shows essentially normal proton transport, but in the photocycle neither of this protein nor of the D212N/R82Q/D96N triple mutant does a deprotonated Schiff base (the M intermediate) accumulate. Instead, the photocycle contains only the K, L, and N intermediates. Infrared difference spectra of D212N/R82Q and D212N/R82Q/D96N demonstrate that although D96 becomes deprotonated in N, D85 remains unprotonated. On the other hand, M is produced at pH > 8, where according to independent evidence the L<==>M equilibrium should shift toward M. Likewise, M is restored in the photocycle when the retinal is replaced with the 14-fluoro analogue that lowers the pKa of the protonated Schiff base, and now D85 becomes protonated as in the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriorhodopsins↗

Conversion of bacteriorhodopsin into a chloride ion pump.

In the light-driven proton pump bacteriorhodopsin, proton transfer from the retinal Schiff base to aspartate-85 is the crucial reaction of the transport cycle. In halorhodopsin, a light-driven chloride ion pump, the equivalent of residue 85 is threonine. When aspartate-85 was replaced with threonine, the mutated bacteriorhodopsin became a chloride ion pump when expressed in Halobacterium salinarium and, like halorhodopsin, actively transported chloride ions in the direction opposite from the proton pump. Chloride was bound to it, as revealed by large shifts of the absorption maximum of the chromophore, and its photointermediates included a red-shifted state in the millisecond time domain, with its amplitude and decay rate dependent on chloride concentration. Bacteriorhodopsin and halorhodopsin thus share a common transport mechanism, and the interaction of residue 85 with the retinal Schiff base determines the ionic specificity.

Aspartic Acid↗

Interaction of tryptophan-182 with the retinal 9-methyl group in the L intermediate of bacteriorhodopsin.

An intense indole N-H stretching vibrational band at 3486 cm-1 in the difference Fourier transform infrared spectrum is one of the characteristic features of the L intermediate of bacteriorhodopsin [Maeda, Sasaki, Ohkita, Simpson, & Herzfeld (1992) Biochemistry 31, 12543]. This band is now assigned to tryptophan-182. The Trp182-->Phe (W182F) protein shows specific features in the difference spectrum in the visible region upon L formation, and exhibits great delay in the L-M conversion. Fourier transform infrared difference spectra further indicate that while the intensity of the C-methyl in-plane bending vibration at 1009 cm-1 is lost in the L intermediate of the wild type, its intensity remains high in the W182F protein. The intensity of the N-H stretching vibration upon L formation is diminished considerably in an artificial bacteriorhodopsin containing 9-desmethylretinal. It also exhibits delayed M formation. These results suggest that Trp182 interacts with the retinal side chain through the 9-methyl group, and thereby affects the L-to-M conversion.

Bacteriorhodopsins↗

Inhibition of viral multiplication in acute and chronic stages of infection by ribozymes targeted against the polymerase gene of mouse hepatitis virus.

Two hammerhead ribozymes targeted against the polymerase gene of mouse hepatitis virus (MHV), which consisted of 22-nucleotide (nt) ribozyme core sequences and antisense sequences of different lengths, 243-nt (S-ribozyme) and 926-nt (L-ribozyme), were tested for their++ inhibitory effects on viral multiplication. Vectors that expressed the ribozymes were transfected into mouse DBT cells and several resulting cell lines constitutively expressing the ribozymes were selected and examined for intracellular MHV multiplication in acute and chronic stages of infection. The production of infectious progeny viral particles was significantly reduced in the transfected cell lines expressing either the S-ribozyme or L-ribozyme in acute infection. Although the in vitro cleavage process of the L-ribozyme was slower than that of the S-ribozyme, no difference was observed in inhibitory effects on MHV multiplication between S- and L-ribozymes in the transfected cells. In the transfected cells expressing L-ribozymes, production of viral particles was also inhibited in the chronic stage of MHV infection.

Animals↗