Biomedical subjects

J Komatsu

Publications and source records attributed to J Komatsu.

At least 19 recordsLinked to original sources

PubMed2002

Improving male mating competitiveness and survival in the field for medfly, Ceratitis capitata (Diptera: Tephritidae) SIT programs.

The success of the sterile insect technique (SIT) depends critically upon mating between released sterilized males and wild females. In Hawaii, improvements in the efficiency of sterile males were attempted on two separate fronts--mating enhancement and survival improvement. In the former, two methods have been investigated--selective breeding and aromatherapy. In the latter, flies which survived in field cages for several days were selected and bred to produce progeny with enhanced survival ability compared to control flies. Regarding mating selection, standard laboratory-reared males that successfully mated with wild females in field cages were allowed to breed. F1 offspring were inbred, then the selection procedure was repeated for four additional cycles. In the aromatherapy procedure, laboratory-reared males were exposed to ginger root oil for several hours 1 day prior to testing in field cages. Compared to controls, the selected flies improved the mating competitiveness of male flies ca. 3-fold, irradiation reduced this increase to ca. 2.5-fold. Exposing the selected, hybrid strain raised the fitness of the lab males to ca. 9-fold that of wild males. In the ongoing survival selection study, we have obtained lines in which the selected males survived ca. 2-fold better than laboratory control males over several days in an outdoor field cage, with food and water provided. The goal is to combine the traits of higher survival and mating ability into a single strain for SIT release.

Animals↗

PubMed2001

Real-time observation of a single DNA digestion by lambda exonuclease under a fluorescence microscope field.

A fluorescence microscopy technique has been developed to visualize the behavior of individual DNA and protein molecules. Real-time direct observation of a single DNA molecule can be used to investigate the dynamics of DNA-protein interactions, such as the DNA digestion reaction by lambda exonuclease. In conventional methods it is impossible to analyze the dynamics of an individual lambda exonuclease molecule on a DNA because they can only observe the average behavior of a number of exonuclease molecules. Observation of a single molecule, on the other hand, can reveal processivity and binding rate of an individual exonuclease molecule. To evaluate the dynamics of lambda exonuclease, a stained lambda DNA molecule with one biotinylated terminal was fixed on an avidin-coated coverslip and straightened using a d.c. electric field. Microscopic observation of digestion of a straightened DNA molecule by lambda exonuclease revealed that the DNA digestion rate was approximately 1000 bases/s and also demonstrated high processivity.

Avidin↗

PubMed2001

Atomic force microscopy of RecA--DNA complexes using a carbon nanotube tip.

We report high resolution images of RecA-double stranded (ds) DNA complexes obtained by atomic force microscopy (AFM). When a carbon nanotube (CNT) tip was used, AFM images visualized the 10-nm pitch of RecA-dsDNA complexes and RecA filaments as three-dimensional surface topography without reconstruction analysis. The depth of the notch between two pitches was less than 1 nm. When adsorbed on a soft surface covered with proteins, naked DNA, RecA monomers, RecA hexamers, and short RecA filaments were all clearly resolved in one image. The high resolution images with a CNT tip provided valuable information on the initiation process of RecA-dsDNA complex formation.

DNA↗

PubMed2000

RecA-double stranded DNA complexes studied by atomic force microscopy.

RecA-double stranded (ds) DNA complexes have been studied by atomic force microscopy (AFM). When the complexes were prepared in the presence of ATP gamma S, fully covered RecA-dsDNA filaments were observed by AFM. When the concentration of RecA proteins was lower, various lengths of filaments were found. The variation of the observed structures may directly reflect the real distribution of the intermediate complexes in the reaction mixture, as the mixture was simply deposited on a mica surface for AFM observation without special fixation or staining. The use of a carbon nanotube (CNT) AFM tip enabled high resolution to reveal the periodicity of RecA-dsDNA filaments. Our observations demonstrated the potential of the AFM method for the structural studies of the RecA-dsDNA complexes, especially their intermediate states.

Adenosine Triphosphate↗

PubMed2000

Significant increase in prostaglandin E-main urinary metabolite by laxative administration: comparison with ulcerative colitis.

OBJECTIVE: To assess the production of prostaglandin E(2), an important chemical mediator in diarrhea induced by laxative administration, a prostaglandin E-main urinary metabolite (7alpha-hydroxy-5,11-diketotetranor-prosta-1,16-dioic acid, PGE-MUM) was measured in healthy volunteers and compared with the values of patients with ulcerative colitis. METHODS: PGE-MUM was determined by a simplified immunoassay of bicyclic PGE-MUM and analyzed for the influence of laxative administration and active/remission phases of ulcerative colitis. RESULTS: Administration of laxatives induced a significant increase in PGE-MUM in healthy volunteers. A significant elevation was also found in the active as compared with the remission phase of ulcerative colitis. The PGE-MUM levels were significantly correlated with our modified Talstad scores, clinical disease activity indices in ulcerative colitis. It was confirmed by time course studies of individual patients that changes in PGE-MUM correlated well with colitis activity. CONCLUSION: Laxative administration induces production of prostaglandin E(2) as one of the chemical mediators, although its production grade is relatively low as compared with ulcerative colitis in the active phase.

Aged↗

PubMed2000

A 25-year-old patient with low cardiac risk factors having a combination of variant angina and severe coronary arterial lesions--a case report.

A 25-year-old man with low cardiac risks underwent coronary arteriography because of chest pain at rest. His only risk factors for coronary artery disease was smoking. Both right and left coronary arteries were ectatic and the left anterior descending artery was obstructed. In the acetylcholine provocation test, the left circumflex coronary artery showed severe constriction. Thus, this patient was diagnosed as having a combination of variant angina and occlusive coronary artery disease.

Adult↗

PubMed1999

Preoperative anal sphincter high pressure zone, maximum tolerable volume, and anal mucosal electrosensitivity predict early postoperative defecatory function after low anterior resection for rectal cancer.

PURPOSE: The aims of this study were to correlate postoperative defecatory function after low anterior resection with clinical factors and physiologic parameters and to explore the possibility of predicting early postoperative defecatory function after low anterior resection. METHODS: Thirty-two patients who underwent low anterior resection for rectal cancer were studied. Anorectal physiologic studies were performed preoperatively and six months postoperatively; maximum resting pressure, maximum squeeze pressure, length of the high pressure zone, neorectal sensory threshold, neorectal maximum tolerable volume, and anal mucosal electrosensitivity were recorded. Preoperative and postoperative defecatory function was scored between 0 (worst) and 6 (best) on the basis of bowel frequency, fecal incontinence, and urgency. RESULTS: In univariate regression analyses, a longer preoperative high pressure zone and a more sensitive anal mucosa were associated with better postoperative defecatory function. Using multiple regression analysis, in which age, gender, the level of anastomosis, and preoperative physiologic parameters were examined as independent variables, a longer preoperative high pressure zone, a larger preoperative maximum tolerable volume, and lower sensory threshold of the anal canal were associated with better postoperative defecatory function. Postoperative function score was found to be predictable using the following formula: 1.47 + 0.496 x high pressure zone (cm) + 0.007 x maximum tolerable volume (ml) - 0.247 x sensory threshold (mA) of the anal canal. CONCLUSION: Early postoperative defecatory function after low anterior resection is predictable from preoperative high pressure zone, maximum tolerable volume, and anal mucosal electrosensitivity.

Aged↗

PubMed1995

Quantitative assessment of anal canal sensation in patients undergoing low anterior resection for rectal cancer.

To determine the influence of anal canal sensation on anal function after low anterior resection (LAR) for rectal cancer, anal canal sensation was quantitatively evaluated before and after LAR by measuring anal mucosal electrosensitivity (AMES), and the relationship between AMES and postoperative and function was explored. Sensory thresholds 1, 2, and 3 cm from the anal margin were recorded in 21 patients who underwent LAR for rectal cancer (LAR-I) before, then 1 and 4 months after their operation. Another 14 patients who had been followed up for more than 1 year (LAR-II) after LAR and 21 control subjects were also studied. The median preoperative sensory thresholds in the LAR-I group were higher than those in the controls, though the differences were not significant. The sensory thresholds in the LAR-I group 4 months after LAR were lower than those preoperatively, but they did not significantly differ from those in the LAR-II and control groups. Although the postoperative sensory thresholds did not correlate with postoperative anal function, the preoperative sensory thresholds were higher in patients who were experiencing episodes of fecal incontinence 4 months after their operation. These results suggests that the preoperative measurement of AMES is useful for identifying patients who are likely to have a poor quality of continence after LAR.

Aged↗

PubMed1988