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Biomedical subjects

K Mikami

Publications and source records attributed to K Mikami.

At least 19 recordsLinked to original sources
PubMed2002

Laparoscopic adrenalectomy for pheochromocytoma.

We reviewed 10 cases of laparoscopic adrenalectomy for pheochromocytoma and compared the results with those of a recent series of 11 patients who underwent open adrenalectomy. Of the 10 cases, the tumor was removed successfully in all cases except in one case with laparoscopy that required open laparotomy. A pair of laparoscopic coagulating scissors was utilized in all except the initial two cases. In the laparoscopy group (excluding the initial two cases and the case that required conversion to open surgery), mean operative time and blood loss were 145 min and 55 ml, respectively. No significant difference was observed in mean operative time between the laparoscopy group and the open surgery group (165 min for open surgery). Mean blood loss of the laparoscopy group was significantly less than that of the open surgery group (330 ml for open surgery, P = 0.01). Mean intervals to first ambulation and oral intake, and postoperative hospital stay of the laparoscopy group, tended to be less than those of the open surgery group, although no statistical significance was observed (2.3 versus 3.2 d, 2.9 versus 3.6 d, and 12 versus 14 d, respectively). We conclude that laparoscopic adrenalectomy for pheochromocytoma is equally effective and less invasive than open adrenalectomy and should be considered the therapy of choice even for pheochromocytoma.

Adolescent↗
PubMed2001

Role of nitric oxide synthase type 2 in acute infection with murine cytomegalovirus.

Whether or not NO plays a critical role in murine CMV (MCMV) infection has yet to be elucidated. In this study, we examined the role of NO in acute infection with MCMV using NO synthase type 2 (NOS2)-deficient mice. NOS2(-/-) mice were more susceptible to lethal infection with MCMV than NOS2(+/+) mice and generated a much higher peak virus titer in the salivary gland after acute infection. A moderate increase in the MCMV titer was also observed in other organs of NOS2(-/-) mice such as the spleen, lung, and liver. The immune responses to MCMV infection including NK cell cytotoxicity and CTL response in NOS2(-/-) mice were comparable with those of NOS2(+/+) mice. Moreover, the ability to produce IFN-gamma is not impaired in NOS2(-/-) mice after MCMV infection. The peritoneal macrophages from NOS2(-/-) mice, however, exhibited a lower antiviral activity than those from NOS2(+/+) mice, resulting in an enhanced viral replication in macrophages themselves. Treatment of these cells from NOS2(+/+) mice with a selective NOS2 inhibitor decreased the antiviral activity to a level below that obtained with NOS2(-/-) mice. In addition, the absence of NOS2 and NOS2-mediated antiviral activity of macrophages resulted in not only an enhanced MCMV replication and a high mortality but also a consequent risk of the latency. It was thus concluded that the NOS2-mediated antiviral activity of macrophages via NO plays a protective role against MCMV infection at an early and late stage of the infection.

Acute Disease↗
PubMed2001

Asymmetric activation of chiral alkoxyzinc catalysts by chiral nitrogen activators for dialkylzinc addition to aldehydes: super high-throughput screening of combinatorial libraries of chiral ligands and activators by HPLC-CD/UV and HPLC-OR/RIU systems.

Asymmetric catalysts, prepared by chiral ligand exchange or chiral modification, can evolve further into highly activated catalysts through engineering with chiral activators. Two new methodologies for "super high-throughput screening" (SHTS) of chiral ligands and activators have been developed as a combination of HPLC-CD/UV (CD/ UV = circular dichroism/ultraviolet spectroscopy) or -OR/RIU (OR/RIU = optical rotation/refractive index unit) with a combinatorial chemistry (CC) factory. With these techniques, the % ee of the product is determined within minutes without separation of the enantiomeric products by using a nonchiral stationary phase. Therefore, those SHTS techniques combined with our 'asymmetric activation' concept can provide a powerful strategy for finding the best activated chiral catalyst.

Journal Article↗
PubMed2001

General synthetic route to chiral flexible biphenylphosphine ligands: the use of a chiral additive enables the preparation and observation of metal complexes incorporating the enantiopure form.

[figure: see text] The enantio- and diastereomerically pure metal complex of a chirally flexible BIPHEP ligand is obtained through enantiomer-selective coordination of a BIPHEP-Ru complex with enantiopure 3,3'-dimethyldiaminobinaphthyl, DM-DBN, followed by epimerization of the remaining BIPHEP-Ru enantiomer to complex with DM-DABN. Thus, an efficient and general synthetic route to a variety of substituted BIPHEP ligands from biphenol and observation of the enantiomerically pure BIPHEP ligands in their Ru(II) complexes are described.

Journal Article↗
PubMed2001

Asymmetric catalytic ene-cyclization approach to 2-fluoro-19-nor-1,25-dihydroxyvitamin D(3) A-ring analog with significant transactivation activity.

1alpha,25-Dihydroxyvitamin D(3) (1alpha,25(OH)2D3) has been shown to modulate not only proliferation and differentiation, but also apoptosis in malignant cells, indicating that it could be useful for the treatment of cancer and psoriasis. However, little information has been available on the binding conformation of the 1alpha,25(OH)2D3 molecule and its analogs with the vitamin D receptor (VDR). Therefore, we synthesized 2alpha-fluorinated A-ring analogs of 19-nor-1alpha,25(OH)2D3 in order to investigate the VDR-binding conformation of the A-rings on the basis of the (19)F NMR analysis. The 2alpha-fluoro-19-nor-1alpha,25-dihydroxyvitamin D3 A-ring analog thus synthesized via a asymmetric catalytic carbonyl-ene cyclization, shows significant activity in transactivation.

Animals↗
PubMed2001

Tetranuclear titanium 7,7'-modified binaphtholate cluster as a novel chiral Lewis acid catalyst.

Chiral tetranuclear Ti cluster, a cubic structure constituted of four Ti atoms and OHs, and six (R)-binaphthols (BINOL) bridged two Ti atoms as ligands, is shown to be a novel chiral Lewis acid catalyst for the [2+3] cycloaddition reaction with nitrones. The chiral Ti clusters with 7,7'-substituted (R)-BINOL ligands was synthesized to give enhanced enantiomeric excesses up to 78% ee.

Journal Article↗
PubMed2001

Obliterative airway disease and graft stenting in pig-to-dog tracheal xenotransplantation.

OBJECTIVE: Obliterative airway disease occurring in concordant tracheal xenografts in rodent models is histologically similar to obliterative bronchiolitis in human lung allografts. We studied whether obliterative airway disease would occur in a large animal-discordant model. METHODS: Pig and dog tracheas were cryopreserved for 7 to 14 days, and 18 recipient dogs given splenectomy 7 days before transplantation, then seven tracheal rings were removed and a corresponding five-ring donor tracheal segment was transplanted to the excised site. Grafts were wrapped with pedicled omentum and inmmunosuppression was conducted with tacrolimus or deoxyspergualin. Graft status was observed by bronchoscopy. Dogs were classified into three groups. Group 1 consisted of dog-to-dog allotransplantation animals (control group, n = 5), Group 2 of pig-to-dog xenotransplantation animals (n = 8), and Group 3 of pig-dog xenotransplantation animals who also underwent graft stenting immediately after transplantation (n = 5). RESULTS: Grafts healed well in 4 of 5 Group 1 dogs. Tracheal stricture began on day 5 post transplantation and the lumen was obstructed by fibrosis by days 8 to 14 in all Group 2 dogs. All Group 3 dogs remained in good respiratory status until death. CONCLUSION: Obliterative airway disease developed quickly in pig-to-dog discordant tracheal xenografts. Graft stenting is a feasible treatment for managing of tracheal obstruction.

Airway Obstruction↗
PubMed2001

Cold-regulated genes under control of the cold sensor Hik33 in Synechocystis.

A histidine kinase, Hik33, appears to sense decreases in temperature and to regulate the expression of certain cold-inducible genes in the cyanobacterium Synechocystis sp. PCC6803. To examine the role of Hik33 in the regulation of gene expression, we analysed a DeltaHik33 mutant using the DNA microarray technique. In wild-type cells, genes that were strongly induced at low temperature encoded proteins that were predominantly subunits of the transcriptional and translational machinery. Most cold-repressible genes encoded components of the photosynthetic machinery. Mutation of the hik33 gene suppressed the expression of some of these cold-regulated genes, which could be divided into three groups according to the effect of the mutation of hik33. In the first group, regulation of gene expression by low temperature was totally abolished; in the second group, the extent of such regulation was reduced by half; and, in the third group, such regulation was totally unaffected. These results suggest that expression of the genes in the first group is regulated solely by Hik33, expression of genes in the third group is regulated by an as yet unidentified cold sensor, and expression of genes in the second group is regulated by both these cold sensors.

Bacterial Proteins↗
PubMed2001

Clinical course and management of patients undergoing open window thoracostomy for thoracic empyema.

BACKGROUND: While open window thoracostomy (OWT) is a safe procedure and is indicated in patients who have thoracic empyema either with or without a bronchopleural fistula, it may prolong the hospital stay. OBJECTIVES: We retrospectively analyzed the relationship between the etiology of thoracic empyema and the open window interval (OWI). METHODS: Between January 1986 and May 1997, 53 patients resistant to conventional therapy underwent OWT for thoracic empyema at the Department of Surgery of the National Minami-Fukuoka Chest Hospital. The patients were classified into five groups based on the etiological findings of thoracic empyema. 44 patients also underwent closure of the window until June 1999. RESULTS: The average OWI was 180.4 +/- 51.9 (mean +/- SE) days for postoperative empyemas in lung cancer, 128.0 +/- 32.1 days for bacterial nontuberculous empyemas, 189.6 +/- 24.1 days for fungal empyemas, 365.8 +/- 201 days for empyemas caused by atypical mycobacteria and 322.0 +/- 58.7 days for tuberculous empyemas. There was no evidence that the OWI was related to either sex, age, etiology of thoracic empyemas, performance status, the existence of bronchopleural fistulae, complications of diabetes mellitus or preoperative malnutrition status in multivariable models. 5 patients underwent a second OWT because of recurrence of empyema. Mortality rate was 7.5%. CONCLUSIONS: There was no relationship between clinical factors including nutritional assessment and OWI. OWT generally is a safe and effective procedure for thoracic empyema resisting to conventional therapy except that it can make an extended hospital stay necessary.

Adult↗
PubMed2000

Chiral Palladium(II)-catalyzed asymmetric glyoxylate-Ene reaction: alternative approach to the enantioselective synthesis of alpha-hydroxy esters

An effective chiral palladium catalyst [Pd(CH(3)CN)(2)(S)-Tol-BINAP](SbF(6))(2) (2b) is developed for asymmetric glyoxylate-ene reactions. This palladium dicationic catalyst provides a simple but efficient approach to the asymmetric synthesis of alpha-hydroxy esters in excellent yields with high enantioselectivities at relatively higher reaction temperature (60 degrees C).

Journal Article↗
PubMed2000

Asymmetric Activation.

While nonracemic catalysts can generate nonracemic products with or without the nonlinear relationship in enantiomeric excesses between catalysts and products, racemic catalysts inherently give only a racemic mixture of chiral products. Asymmetric catalysts, either in nonracemic or racemic form, can be further evolved into highly activated catalysts with association of chiral activators. This asymmetric activation process is particularly useful in racemic catalysis through selective activation of one enantiomer of the racemic catalyst. Recently, a strategy whereby a racemic catalyst is selectively deactivated by a chiral additive has been reported to yield nonracemic products. However, reported herein is an alternative and conceptually opposite strategy in which a chiral activator selectively activates, rather than deactivates, one enantiomer of a racemic chiral catalyst. The advantage of this activation strategy over the deactivation counterpart is that the activated catalyst can produce a greater enantiomeric excess in the products-even with the use of a catalytic amount of activator relative to chiral catalyst-than that attained by the enantiomerically pure catalyst on its own. Therefore, asymmetric activation could provide a general and powerful strategy for not only the use of atropisomeric, racemic ligands but also chirally flexible and proatropisomeric ligands without enantiomeric resolution!

Journal Article↗
PubMed2000

The pathway for perception and transduction of low-temperature signals in Synechocystis.

Low temperature is an important environmental factor that has effects on all living organisms. Various low-temperature-inducible genes encode products that are essential for acclimation to low temperature, but low-temperature sensors and signal transducers have not been identified. However, systematic disruption of putative genes for histidine kinases and random mutagenesis of almost all the genes in the genome of the cyanobacterium Synechocystis sp. PCC 6803 have allowed us to identify two histidine kinases and a response regulator as components of the pathway for perception and transduction of low-temperature signals. Inactivation, by targeted mutagenesis, of the gene for each of the two histidine kinases and inactivation of the gene for the response regulator depressed the transcription of several lowtemperature-inducible genes.

Bacterial Proteins↗
PubMed2000

Optical rotation per refractive index unit, or enantiomeric (e) factor, for screening enantioselective catalysts through asymmetric activation or carbohydrates.

A super high-throughput screening (SHTS) system can be constructed by combining high-performance liquid chromatography (HPLC), optical rotation (OR), and refractive index unit (RIU) to determine not only the enantioselectivity of the addition of diethylzinc to an aliphatic aldehyde catalyzed by a binaphthol-zinc complex through asymmetric activation with chiral Schiff bases, but also the enantiopurity of a carbohydrate. The enantiomeric (e) factor, which we define here as optical rotation per refractive index unit, is linearly related to the percent enantiomeric excess (%ee) and is independent of concentration.

Acetonitriles↗
PubMed2000

Laparoscopic adrenalectomy for functioning adrenal tumors: clinical experiences with 38 cases and comparison with open adrenalectomy.

We reviewed 38 cases of transperitoneal or retroperitoneal laparoscopic adrenalectomy for unilateral benign functioning adrenal tumors and compared the results with those of a recent series of 36 patients undergoing an open adrenalectomy. The tumors were removed successfully in all but two cases with laparoscopy that required open laparotomy. In the other 36 cases of the laparoscopy group, mean operative time and blood loss were 225 minutes and 138 mL, respectively. Mean operative time was significantly longer for the laparoscopy group (122 minutes for open surgery: P < 0.0001), whereas mean blood loss of the laparoscopy group was almost equal to that of the open surgery group. Mean intervals to first ambulation and oral intake, and postoperative hospital stay of the laparoscopy group were significantly less than those of the open surgery group (1.4 vs 2.0 days: P = 0.014; 1.8 vs 2.9 days: P < 0.0001; and 8.5 vs 12.9 days: P < 0.0001, respectively). We conclude that laparoscopic adrenalectomy is equally effective and less invasive than open adrenalectomy. and that it should be considered as the first-choice therapy for benign adrenal tumors.

Adrenal Gland Neoplasms↗