PubMed Health⌕ Search

Biomedical subjects

Makoto Kato

Publications and source records attributed to Makoto Kato.

9 recordsLinked to original sources
PubMed2003

An obligate pollination mutualism and reciprocal diversification in the tree genus Glochidion (Euphorbiaceae).

Highly coevolved pollination mutualism accompanied by reciprocal diversification has been known in only two plant genera, Ficus (Moraceae) and Yucca (Agavaceae), which are pollinated exclusively by obligate seed-parasitic wasps and moths, respectively. An additional, highly diversified, species-specific pollination mutualism between a monoecious tree genus, Glochidion (Euphorbiaceae), and a moth genus, Epicephala (Gracillariidae), is presented here. At night, the small female moth actively deposits pollen on the cryptic stigma of the female flower by using its proboscis, then oviposits into the style. The moth larva infests only a portion of the developing seeds within fruit. We confirmed that at least three Glochidion species are pollinated only by their respective seed-parasitic moth species, which could be distinguished by genitalic morphology and mitochondrial DNA sequences. These results and widespread evidence of limited seed infestation by the moths associated with Glochidion species suggest that speciation based on the highly specialized Glochidion stylar structure and moth oviposition behavior have promoted species diversification in Glochidion and its pollinators.

Animals↗
PubMed2003

Mucocele-like tumor of the breast caused by ductal carcinoma in situ: a case report.

A mucocele-like tumor (MLT) of the breast caused by clinging and micropapillary carcinoma in situ is reported. The tumor was a smooth-contoured mass located near the nipple in the lower inner quadrant of the left breast. Ultrasonography showed a cystic tumor and distended ducts. An aspiration specimen contained abundant mucinous material and a small amount of epithelial cell components, but was insufficient for cytological diagnosis. An excisional biopsy specimen disclosed multiple cysts containing mucin with extravasation into the stroma. Additional pathologic diagnosis using consecutive microscopic sections demonstrated ductal carcinoma in situ. Subcutaneous mastectomy was subsequently performed. Histopathologic findings in the resected and biopsy specimens indicated a diagnosis of MLT caused by widely spreading clinging and micropapillary ductal carcinoma in situ. The ductal epithelium of the MLT in an open biopsy specimen must be carefully examined using consecutive microscopic sections to detect occult DCIS.

Adult↗
PubMed2003

Information flow related to visual search assessed using magnetoencephalography.

The sequence of neural activation during a visual search task was investigated using magnetoencephalography and the source locations for the activations were analyzed using a single-dipole algorithm. Five components (M1-5) were detected at mean latencies of 110, 146, 196, 250 and 333 ms in both of two different stimulus conditions; a target popped out in one stimulus condition (pop-out), while it did not in the other condition (non-pop-out). Statistical analysis showed that the M3 amplitude was larger and the M5 latency was shorter in the pop-out condition than in the non-pop-out condition, while there was no difference in the other components between the conditions. Neural sources were localized in the calcarine sulcus (M1) and the posterior fusiform gyrus (M2) of the hemisphere contralateral to the stimuli, the intraparietal sulcus and the posterior superior temporal sulcus (M3) in either of the hemispheres, and the calcarine sulcus (M4) of the same hemisphere in which the early processing (M1 and M2) occurred. The criteria for source localization were not satisfied for M5. The results suggest that the processing for pop-out and non-pop-out stimuli share a common mechanism; after early feature processing in the occipital cortex (M1 and M2), visual information is processed in the parietal and temporal regions (M3) and then some of this information is fed back to the occipital cortex (M4).

Adult↗
PubMed2003

Functional MRI of brain activation evoked by intentional eye blinking.

Eye blinking is not only a reflexive action to protect the ocular surface from injury and desiccation; it can also be done intentionally. However, only a few studies have investigated the brain mechanism controlling intentional blinking, and there are still inconsistencies among the reported activation patterns in the human brain evoked by intentional blinking. In monkeys, some areas where blinking is evoked by electrical microstimulation have been found in the premotor areas and in the posterior parietal cortex. But there have been no reports about neuronal activity related to blinking in the cerebral cortex. In the present study, the brain activation evoked by intentional blinking was examined in humans by using fMRI, and the activations were found in the middle precentral gyrus, but not in the posterior parietal cortex, suggesting that the premotor areas, rather than the posterior parietal cortex, are important for controlling intentional blinking.

Adult↗
PubMed2003

Human precentral cortical activation patterns during saccade tasks: an fMRI comparison with activation during intentional eyeblink tasks.

Some fMRI studies in humans have located the frontal eye field (FEF) in two distinct regions along the precentral sulcus (PCS): one localized more medically, in the superior precentral sulcus (supPCR) at the junction with the superior frontal sulcus, and the other localized more laterally, along the medial part of the inferior precentral sulcus (infPCR). However, there has been no evidence of any different task activations between the regions. In the present study using fMRI, we have compared activation patterns in the regions near the PCS during saccade, fixation, and eyeblink tasks. We found that only the supPCR was activated specifically by the saccade task, while the infPCR was activated by both the saccade and eyeblink tasks. This result provides evidence that the supPCR is the human FEF homologous to the monkey FEF and that the infPCR may be homologous to the monkey premotor area.

Adult↗
PubMed2003

Evolution and phylogenetic utility of alignment gaps within intron sequences of three nuclear genes in bumble bees (Bombus).

To test whether gaps resulting from sequence alignment contain phylogenetic signal concordant with those of base substitutions, we analyzed the occurrence of indel mutations upon a well-resolved, substitution-based tree for three nuclear genes in bumble bees (Bombus, Apidae: Bombini). The regions analyzed were exon and intron sequences of long-wavelength rhodopsin (LW Rh), arginine kinase (ArgK), and elongation factor-1alpha (EF-1alpha) F2 copy genes. LW Rh intron had only a few uninformative gaps, ArgK intron had relatively long gaps that were easily aligned, and EF-1alpha intron had many short gaps, resulting in multiple optimal alignments. The unambiguously aligned gaps within ArgK intron sequences showed no homoplasy upon the substitution-based tree, and phylogenetic signals within ambiguously aligned regions of EF-1alpha intron were highly congruent with those of base substitutions. We further analyzed the contribution of gap characters to phylogenetic reconstruction by incorporating them in parsimony analysis. Inclusion of gap characters consistently improved support for nodes recovered by substitutions, and inclusion of ambiguously aligned regions of EF-1alpha intron resolved several additional nodes, most of which were apical on the phylogeny. We conclude that gaps are an exceptionally reliable source of phylogenetic information that can be used to corroborate and refine phylogenies hypothesized by base substitutions, at least at lower taxonomic levels. At present, full use of gaps in phylogenetic reconstruction is best achieved in parsimony analysis, pending development of well-justified and generally applicable methods for incorporating indels in explicitly model-based methods.

Animals↗
PubMed2002

Prognostic power of ventilatory responses during submaximal exercise in patients with chronic heart disease.

BACKGROUND: Although parameters obtained during submaximal exercise are known to be useful for predicting mortality in cardiac patients, it has been a matter of debate whether the submaximal parameters are superior to peak oxygen uptake (VO(2)). For this purpose, we aimed to determine the best index among exercise variables in predicting long-term mortality in patients with chronic heart disease. METHODS: The study population consisted of 385 consecutive patients with chronic heart disease who performed a symptom-limited incremental exercise test on a cycle ergometer. Breath-by-breath respiratory gas analysis was used to estimate the peak VO(2), the ratio of the increase in VO(2) to the increase in work rate (WR) [VO(2)/Delta WR], and the ratio of the increase in minute ventilation E to the increase in carbon dioxide output (VCO(2)) [Delta VE/Delta VCO(2)]. RESULTS: After 1,899 +/- 495 days of follow-up (mean +/- SD), 33 cardiovascular-related deaths occurred. Nonsurvivors achieved lower peak VO(2), lower VO(2)/Delta VWR, and higher Delta VE/Delta VCO(2) compared to the survivors. In the univariate Cox proportional hazards analysis, peak VO(2), VO(2)/Delta VWR, and Delta VE/Delta VCO(2) were found to be significant prognostic indexes of survival. However, multivariate analysis revealed O(2)/Delta VWR as an independent predictor of mortality and Delta VE/delta VCO(2) as a slightly weaker predictor. In this analysis, the prognostic power of peak O(2) was insignificant. CONCLUSION: Submaximal respiratory gas indexes are very likely to be more sensitive than peak VO(2) for predicting poor survival in ambulatory patients with chronic heart disease.

Carbon Dioxide↗
PubMedDate not supplied

Resection of an icteric type hepatoma with tumor thrombi filling the right posterior bile duct.

A 67-year-old male with jaundice was found to have hepatocellular carcinoma in the right hepatic lobe and tumor thrombi in the common hepatic duct. Physicians initially considered the tumor unresectable, and treated the patient with transcatheter arterial infusion chemotherapy and biliary endoprosthesis. The patient developed a liver abscess after the second transcatheter arterial infusion, and the physicians consulted our department for another form of therapy. Percutaneous transhepatic biliary drainage was performed to relieve revived obstructive jaundice. Cholangiography revealed tumor thrombi extending through the right posterior segmental bile duct into the common hepatic duct. Most biliary branches of the caudate lobe joined with the left lateral posterior segmental branch. Arterial and portal venous branches of the caudate lobe were not involved. Right hepatic lobectomy and extrahepatic bile duct resection were performed 1 year after initial diagnosis. On histologic examination, the epithelium of the right posterior segmental bile duct, which was filled with the tumor thrombi, was not detected. The patient is alive without recurrence 24 months after surgery. Careful investigation of biliary branches of the caudate lobe on cholangiography is essential to determine the necessity of caudate lobectomy in patients with hepatocellular carcinoma and tumor thrombi filling the right posterior segmental bile duct.

Aged↗