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Biomedical subjects

K Koga

Publications and source records attributed to K Koga.

At least 19 recordsLinked to original sources
PubMed2006

Recurrence of ovarian endometrioma after laparoscopic excision.

BACKGROUND: To analyse risk factors that influence the recurrence of endometrioma after laparoscopic excision. METHODS: A total of 224 patients who had a minimum of 2 years of post-operative follow-up after laparoscopic ovarian endometrioma excision were studied retrospectively. Recurrence was defined as the presence of endometrioma more than 2 cm in size, detected by ultrasonography within 2 years of surgery. Fourteen variables (age, presence of infertility, pain, uterine myoma, adenomyosis, previous medical treatment of endometriosis, previous surgery for ovarian endometriosis, single or multiple cysts, the size of the largest cyst at laparoscopy, unilateral or bilateral involvement, co-existence of deep endometriosis, revised American Society for Reproductive Medicine (ASRM) score, post-operative medical treatment and post-operative pregnancy) were evaluated to assess their independent effects on the recurrence using logistic regression analysis. RESULTS: The overall rate of recurrence was 30.4% (68/224). Significant factors that were independently associated with higher recurrence were previous medical treatment of endometriosis [odds ratio (OR) = 2.324, 95% confidence interval (95% CI) = 1.232-4.383, P = 0.0092) and larger diameter of the largest cyst (OR = 1.182, 95% CI = 1.004-1.391, P = 0.0442). Post-operative pregnancy was associated with lower recurrence (OR = 0.292, 95% CI = 0.028-0.317, P = 0.0181). CONCLUSIONS: Previous medical treatment of endometriosis or large cyst size was a significant factor that was associated with higher recurrence of the disease. Post-operative pregnancy is a favourable prognostic factor.

Adult↗
PubMed2005

Gli1, downregulated in colorectal cancers, inhibits proliferation of colon cancer cells involving Wnt signalling activation.

BACKGROUND: Early events in the progression of 90% of sporadic colorectal cancers depend on constitutive activation of Wnt signalling. Recent data also indicate a close association between the Hedgehog (Hh) and Wnt pathways in colonic epithelial cell differentiation. AIMS: To investigate whether expression of Gli1, a transactivator of Hh signalling, can suppress Wnt signalling and inhibit proliferation of human colorectal cancer cells. METHODS: Gli1 and nuclear beta-catenin expression were examined in a series of 40 human colorectal cancers by immunohistochemistry. We quantified Gli1 and nuclear beta-catenin staining as markers of Hh and Wnt pathway activation, respectively. Two human colon cancer cell lines, SW480 and HCT116, with mutations in APC and beta-catenin, respectively, were used. The effects of Gli1 overexpression on Wnt transcriptional activity, beta-catenin subcellular distribution, and proliferation in these cells were analysed. RESULTS: Nuclear accumulation of beta-catenin and the Gli1 staining level were inversely associated in the 40 human colorectal cancers. Wnt transcriptional activity was reduced in Gli1 transfected cells. These effects were observed even in Gli1 transfected cells cotransfected with mutated beta-catenin. Furthermore, nuclear accumulation of beta-catenin was diminished compared with that in empty vector transfected cells, and downregulated transcription of c-Myc was observed in Gli1 transfected cells. Proliferation of Gli1 transfected cells was also significantly suppressed compared with that in empty vector transfected cells. CONCLUSIONS: Our data suggest that Gli1 plays an inhibitory role in the development of colorectal cancer involving Wnt signalling, even in cases with the stabilising mutation of beta-catenin.

Carrier Proteins↗
PubMed2005

Bacterial luciferase activity and the intracellular redox pool in Escherichia coli.

In this study, we analyzed the activity of a bacterial luciferase (LuxAB of Vibrio fischeri) expressed under the control of a consensus-type promoter, lacUV5, in Escherichia coli, and found that activity declines abruptly upon entry into the stationary growth phase. Since this decline was reproducibly observed in strains cultured in various growth media, we refer to this phenomenon as ADLA (Abrupt Decline of Luciferase Activity) and define the time point when activity begins to decline as T (0). Because the levels of luciferase proteins (LuxA and LuxB) remained constant before and after T (0), ADLA cannot be due to the repression of luciferase gene expression. Further analyses suggested that a decline in the supply of intracellular reducing power for luciferase was responsible for ADLA. We also found that ADLA was alleviated or did not occur in several mutants deficient in nucleoid proteins, suggesting that ADLA is a genetically controlled process involved in intracellular redox flow.

Aliivibrio fischeri↗
PubMed2005

Differential expression of a Bombyx mori AHA1 homologue during spermatogenesis.

The AHA1 (activator of Hsp90 ATPase) family of proteins were exclusively conserved from yeast to humans, but little is known about their tissue distribution or biological function. In this study, a cDNA for a Bombyx mori AHA1 homologue, BmAHA1, was isolated from the testes of larvae on day 3 of the fifth instar using an mRNA differential display method. This cDNA encodes a protein with 341 amino acid residues. Gene expression studies revealed that BmAHA1 mRNA occurred prominently in the testes. In situ hybridization and immunostaining showed that the BmAHA1 mRNA signals were strongly detected in spermatogonial cells and primary spermatocytes at the fifth larval instar stage, whereas the BmAha1 protein was abundant in round and elongated spermatids at the pupal stage. The localization pattern of the accumulated protein in the elongated spermatids was reminiscent of that reported previously for microtubules, but the BmAha1 protein showed a decrease in apparent concentration during maturation process. The stage- and cell-specific expression indicated that BmAha1 might play a role in silkworm spermatogenesis, especially in postmeiotic differentiation.

Animals↗
PubMed2004

Usefulness of epidural anesthesia in gynecologic laparoscopic surgery for infertility in comparison to general anesthesia.

BACKGROUND: Although the advantages of epidural anesthesia in open surgery have been established, its usefulness in the setting of laparoscopic surgery remains to be studied. METHODS: Patients undergoing laparoscopic surgery for infertility were randomly administered epidural anesthesia (group A, n = 11) or general anesthesia (group B, n = 9). The operation was performed under 4 mmHg pneumoperitoneum and in the 20 degrees Trendelenburg position. Respiratory function tests using a spirometer and blood gas analysis were performed during the intra- or perioperative period. Pain status was evaluated with visual analog scale scoring. The number of postoperative recovery days needed to resume daily activities was obtained by a questionnaire. RESULTS: Respiratory rate, minute volume, P(a)CO2, % vital capacity (VC), and forced expiratory volume in 1 s (FEV1) % were virtually constant throughout the study period in group A, whereas %VC was decreased immediately after operation in group B (p < 0.05). Minute volume immediately after operation was significantly increased in group B compared with group A (p < 0.01), suggesting shallow respiration in women undergoing general anesthesia. Observed pain scores on abdominal pain, shoulder pain, and dyspnea were very low during operation in group A. Pain scores immediately and 3 h after operation were also minimal in group A, whereas abdominal pain scores at these points were significantly higher in group B than those in group A (both p < 0.01). The number of days required for a half reduction in wound pain, trotting, and full recuperation for group A were less than those for group B (p < 0.05). CONCLUSIONS: Epidural anesthesia, when used in laparoscopic surgery for infertility treatment, has advantages over general anesthesia in terms of analgesic effects, postoperative respiratory function, and a return to preoperative daily activities.

Adult↗
PubMed2004

[Type A dissection caused by aortic cannulation during coronary artery bypass grafting; report of a case].

A 71-year-old woman who had severe stenosis in the origin of the left anterior descending coronary artery with large diagonal branch was scheduled for coronary artery bypass grafting (CABG). After harvesting of bypass conduits, aortic cannulation was performed into the ascending aorta. Immediately after insertion of the cannula, however, the ascending aorta changed to a bluish color. Epiaortic ultrasonography revealed aortic dissection. Replacement of the ascending aorta was carried out using circulatory arrest under deep hypothermia. The intimal tear was located at the cannulation site. After this procedure, scheduled CABG the left internal thoracic artery to the left anterior descending coronary artery and the saphenous vein graft to the diagonal branch was performed. The proximal site of the saphenous vein graft was anastomosed to the replaced graft. The postoperative course was uneventful. Rapid identification and appropriate surgical management are necessary to minimize patient morbidity and mortality.

Aged↗
PubMed2003

Progress in pursuit of therapeutic A2A antagonists: the adenosine A2A receptor selective antagonist KW6002: research and development toward a novel nondopaminergic therapy for Parkinson's disease.

Research and development of the adenosine A2A receptor selective antagonist KW6002 have focused on developing a novel nondopaminergic therapy for Parkinson's disease (PD). Salient pharmacologic features of KW6002 were investigated in several animal models of PD. In rodent and primate models, KW6002 provides symptomatic relief from parkinsonian motor deficits without provoking dyskinesia or exacerbating existing dyskinesias. The major target neurons of the A2A receptor antagonist were identified as GABAergic striatopallidal medium spiny neurons. A possible mechanism of A2A receptor antagonist action in PD has been proposed based on the involvement of striatal and pallidal presynaptic A2A receptors in the "dual" modulation of GABAergic synaptic transmission. Experiments with dopamine D2 receptor knockout mice showed that A2A receptors can function and anti-PD activities of A2A antagonists can occur independent of the dopaminergic system. Clinical studies of KW6002 in patients with advanced PD with L-dopa-related motor complications yielded promising results with regard to motor symptom relief without motor side effects. The development of KW6002 represents the first time that a concept gleaned from A2A biologic research has been applied successfully to "proof of concept" clinical studies. The selective A2A antagonist should provide a novel nondopaminergic approach to PD therapy.

Adenosine A2 Receptor Antagonists↗
PubMed2003

Essential Bacillus subtilis genes.

To estimate the minimal gene set required to sustain bacterial life in nutritious conditions, we carried out a systematic inactivation of Bacillus subtilis genes. Among approximately 4,100 genes of the organism, only 192 were shown to be indispensable by this or previous work. Another 79 genes were predicted to be essential. The vast majority of essential genes were categorized in relatively few domains of cell metabolism, with about half involved in information processing, one-fifth involved in the synthesis of cell envelope and the determination of cell shape and division, and one-tenth related to cell energetics. Only 4% of essential genes encode unknown functions. Most essential genes are present throughout a wide range of Bacteria, and almost 70% can also be found in Archaea and Eucarya. However, essential genes related to cell envelope, shape, division, and respiration tend to be lost from bacteria with small genomes. Unexpectedly, most genes involved in the Embden-Meyerhof-Parnas pathway are essential. Identification of unknown and unexpected essential genes opens research avenues to better understanding of processes that sustain bacterial life.

Bacillus subtilis↗
PubMed2003

Ankylosis of the temporomandibular joint developing shortly after multiple facial fractures.

A 41-year-old male patient was referred for treatment of extensive facial fractures and lateral condylar dislocations. The patient underwent open reduction and fixation under general anaesthesia. Intermaxillary fixation was released in 2 weeks and mouth opening was 21 mm. Despite postoperative physical exercises, the range of motion decreased to 10 mm at 5 weeks after the surgery. MR arthrography revealed a fibrous ankylosis in the bilateral TMJs. Coronal CT scans depicted a bony outgrowth of the left TMJ tuber. The patient underwent surgery for the ankylosis including discectomy and coronoidectomy, and removal of the bony outgrowth. An interincisal distance of 30 mm on maximal mouth opening has been maintained for 14 postoperative months. The importance of imaging assessment was emphasized for diagnosing the precise pathologic state of the ankylosis and selecting an appropriate surgical treatment of choice.

Adult↗
PubMed2003

Evaluation of two algorithms for counting forward saccades in a reading task.

We compared two algorithms, which are used to assess the number of forward saccades in a reading task from records of eye movements. In one algorithm saccades are detected analysing the velocity of eye movements. The third derivate of eye position in time (jerk) is used in the second algorithm for the detection of saccades. Both algorithms were applied on the same set of data, recorded using 24 subjects reading a German text, which was presented on two different displays. Our subjects read the text at a mean reading speed of 258.5 word/min. Both algorithms were found to produce a similar rate of artefacts in the number of detected saccades (2.5%), provided the threshold for detection (velocity or jerk) is set at an appropriate level and the same level of threshold is applied to all data. In both algorithms, the rate of artefacts increases with increasing distance of the threshold from its optimum. Inter-individual variation of the rate of artefacts increases more pronounced in the algorithm based on jerks. Eye blinks were identified as a major source of artefacts. A remedy is proposed, by means of which the rate of artefacts can be reduced.

Adult↗
PubMed2002

Effects of gonadotropin-releasing hormone analog treatment on skin condition.

The skin is a target organ of estrogens. Thus, theoretically, a hypoestrogenic state induced by gonadotropin-releasing hormone analog (GnRHa) treatment may have effects on skin condition. The aim of this study was to evaluate skin condition during GnRHa treatment. Sixteen premenopausal women undergoing GnRHa treatment for 16 weeks, as a presurgical treatment for uterine leiomyomas, were studied. Measurement of serum estradiol levels and epidermal hydration, and evaluation of subjective findings on skin condition using a questionnaire, were performed every 4 weeks during the treatment period. Serum estradiol levels were significantly suppressed at 4 weeks of treatment, and remained low afterwards. Epidermal hydration measured by corneometer did not show any significant difference at any time point examined, compared with that before treatment. No particular subjective findings relating to the skin (dryness, wrinkling, roughness, pigmentation, itching, formication, reaction to cosmetics) were reported during treatment, whereas complaints about hot flushes and sweating were notable. The results of this preliminary study support the notion that GnRHa treatment for 16 weeks is unassociated with apparent changes in skin condition.

Adult↗
PubMed2002

Serum levels of glucose-derived advanced glycation end products are associated with the severity of diabetic retinopathy in type 2 diabetic patients without renal dysfunction.

Reducing sugars can react nonenzymatically with the amino groups of proteins to form Amadori products and subsequently cross-linked, heterogeneous fluorescent derivatives called advanced glycation end products (AGE). AGE can arise in vivo from various types of reducing sugars or dicarbonyl compounds and their formation and accumulation are known to progress during normal aging. In individuals with diabetes mellitus, this progression is greatly accelerated. The aim of the present study was to investigate which kinds of serum AGE components were associated with the severity of diabetic retinopathy in 72 type 2 diabetic patients without renal dysfunction. Serum levels of glucose-, glyceraldehyde- or methylglyoxal-derived AGE (methyl-AGE) were measured by an enzyme-linked immunosorbent assay. No significant correlations were found between serum levels of various AGE and HbA1c level, current age, systolic and diastolic pressure, diabetes duration, serum creatinine or blood urea nitrogen level in type 2 diabetic patients. A significant elevation of serum glucose-AGE was found to be associated with severity of diabetic retinopathy. While no differences in serum methyl-AGE levels were found between patients with diabetic retinopathy and those without, serum levels of glyceraldehyde-AGE showed a tendency to increase as normal retinal status advanced to simple and proliferative retinopathy (p = 0.06). The present results suggest that among various types of AGE, glucose-AGE serum levels may be a useful marker of diabetic retinopathy in type 2 diabetic patients without renal dysfunction.

Diabetes Mellitus, Type 2↗
PubMed2002

Dilazep hydrochloride, an antiplatelet drug, prevents progression of diabetic nephropathy in Otsuka Long-Evans Tokushima fatty rats.

Diabetic nephropathy is a leading cause of end-stage renal disease in industrialized countries. Although the mechanisms for the development and progression of diabetic nephropathy are not fully understood, platelet activation may participate in its pathogenesis by promoting microthrombus formation. In this study, we investigated the effects of dilazep hydrochloride, an antiplatelet agent, on the development and progression of diabetic nephropathy in Otsuka Long-Evans Tokushima fatty (OLETF) rats, a type 2 diabetes mellitus animal model. Administration of dilazep hydrochloride significantly reduced the increase of urinary protein excretions and N-acetyl-beta-D-glucosaminidase (NAG) activity in OLETF rats. Furthermore, dilazep hydrochloride treatment prevented glomerulosclerosis and tubular atrophy and reduced positive staining for type IV collagen in the glomeruli of diabetic rats. These results indicate that platelet activation plays a dominant role in the development and progression of diabetic nephropathy. Our study suggests that dilazep hydrochloride is a valuable new drug for the treatment of diabetic patients with nephropathy.

Acetylglucosaminidase↗
PubMed2001

Altered psychomotor behaviors in mice lacking pituitary adenylate cyclase-activating polypeptide (PACAP).

Pituitary adenylate cyclase-activating polypeptide (PACAP) has been conserved remarkably during evolution and is widely expressed in the mammalian brain. In Drosophila, mutation of the PACAP homologue results in behavioral defects, including impaired olfaction-associated learning and changes in ethanol sensitivity. Here, we report the generation of mice lacking the PACAP gene (PACAP(-/-)). PACAP(-/-) mice were born in the expected Mendelian ratios but had a high early-mortality rate. The surviving adult PACAP(-/-) mice displayed remarkable behavioral changes; they exhibited hyperactive and explosive jumping behaviors in an open field, increased exploratory behavior, and less anxiety in the elevated plus maze, emergence, and novel-object tests. Analysis of PACAP(-/-) mice brains revealed that the serotonin metabolite 5-hydroxyindoleacetic acid was slightly decreased in the cortex and striatum compared with wild-type mice. The present study provides evidence that PACAP plays a previously uncharacterized role in the regulation of psychomotor behaviors.

Animals↗
PubMed2001

Formation of ordered ice nanotubes inside carbon nanotubes.

Following their discovery, carbon nanotubes have attracted interest not only for their unusual electrical and mechanical properties, but also because their hollow interior can serve as a nanometre-sized capillary, mould or template in material fabrication. The ability to encapsulate a material in a nanotube also offers new possibilities for investigating dimensionally confined phase transitions. Particularly intriguing is the conjecture that matter within the narrow confines of a carbon nanotube might exhibit a solid-liquid critical point beyond which the distinction between solid and liquid phases disappears. This unusual feature, which cannot occur in bulk material, would allow for the direct and continuous transformation of liquid matter into a solid. Here we report simulations of the behaviour of water encapsulated in carbon nanotubes that suggest the existence of a variety of new ice phases not seen in bulk ice, and of a solid-liquid critical point. Using carbon nanotubes with diameters ranging from 1.1 nm to 1.4 nm and applied axial pressures of 50 MPa to 500 MPa, we find that water can exhibit a first-order freezing transition to hexagonal and heptagonal ice nanotubes, and a continuous phase transformation into solid-like square or pentagonal ice nanotubes.

Journal Article↗
PubMed2001

Linearization and integration of DNA into cells preferentially occurs at intrinsically curved regions from human LINE-1 repetitive element.

A bent DNA library was constructed from human genomic DNA, from which a new clone belonging to the human LINE-1 sequence family was isolated and characterized. This clone, with a length of 378 base pairs and termed HBC-1 (human bent clone-1), contained an intrinsically occurring curved DNA structure. By permutation analysis, the center of curvature of this fragment was mapped onto the nucleotide position 886 from the 5' terminus of the complete LINE-1 sequence. Reporter plasmids, which contain HBC-1, were effectively integrated into human chromosome, indicating that the bent DNA structure provides a preferential donor site for the integration of human LINE-1 sequences. The present finding may provide an explanation as to why some inactivated LINE-1 sequences on human chromosomes carry the deletion at their 5' termini.

3T3 Cells↗