Biomedical subjects

H Kanazawa

Publications and source records attributed to H Kanazawa.

At least 91 records · Page 5Linked to original sources

PubMed1998

[Transjugular intrahepatic portosystemic shunt for the treatment of refractory ascites].

Five cirrhotic patients with refractory ascites were treated with transjugular intrahepatic portosystemic shunt (TIPS). Before TIPS, although patients were received salt restriction (5 g/day), diuretic therapy (furosemide 112 mg/day, spironolactone 140 mg/day), albumin infusion and paracentesis, ascites did not show improvement. After TIPS, urine volume and urinary sodium excretion increased significantly. Mean body weight decreased significantly from 73 kg before TIPS to 63 kg a month after TIPS. Improvement of ascites after TIPS were associated with a significant reduction in the dose of diuretics. On discharge, complete resolution of ascites was found in 2 patients and mild ascites remained in 3 other patients. Four patients presented 6 episodes of shunt stenosis in the follow-up period, and were treated with balloon dilatation. Ascites increased on shunt dysfunction and showed improvement after balloon dilatation. Post-TIPS encephalopathy was seen in 2 patients and one of 2 was disabled. In conclusion, although post-TIPS shunt dysfunction and encephalopathy are common. TIPS is an effective therapy for refractory ascites in patients with cirrhosis.

Ascites↗

PubMed1998

[Traumatic aortic regurgitation: report of two surgical cases].

Two successful surgical cases with aortic regurgitation due to blunt trauma are reported. Case 1: A 48-year-old female was transferred to our hospital after a traffic accident. She was intubated and mechanically ventilated. Twelve days later, echocardiography demonstrated massive aortic regurgitation. The next day, aortic valve replacement was performed using a 21 mm SJM mechanical valve. The central part of the non-coronary cusp was torn and perforated 15 mm long. She is in good condition three years after surgery. Case 2: A 57-year-old male was transferred to the nearest hospital because he was involved in a snowslide accident. A month after the injury, catheterization showed massive aortic regurgitation and pulmonary hypertension. An aortotomy revealed that the intima around the right coronary ostium was completely torn. A perforation with a diameter of 3 mm was also observed on the right coronary cusp. After coronary cusps were excised, interrupted mattress sutures buttressed with pledgets were passed through the aortic wall at the distal level of the intimal laceration and then to the aortic annulus. A 25 mm SJM prosthetic valve was seated at the aortic ring. As the right coronary ostium was included in the plicated aortic wall, aortocoronary bypass was constructed using the great saphenous vein. He is doing well 14 months after surgery. Aortic regurgitation due to blunt trauma is rare and difficult to diagnose. Sometimes cardiac failure progresses rapidly. Therefore, urgent surgery is recommended as soon as the diagnosis is confirmed.

Aortic Aneurysm↗

PubMed1997

Subunit interactions of Escherichia coli F1-ATPase: mutants of the gamma subunits defective in interaction with the epsilon subunit isolated by the yeast two-hybrid system.

Previously, we established a method to detect subunit interactions of F1-ATPase by the yeast two-hybrid system (Moritani, C., et al. Biochim. Biophys. Acta 1274, 67-72, 1996). Here, we isolated mutants of the gamma subunits defective in interaction with the epsilon subunit by this new procedure to study the molecular basis of coupling mechanisms of the F1F0-ATPase. Based on the intensities of the reporter gene expression in this system, five mutants of the gamma subunit with different levels of gamma-epsilon interactions were isolated and their single base substitutions were determined. Mutants with a substitution of Pro-55 for Leu, Thr-102 for Met, Val-141 for Asp, or Gln-235 for Leu exhibited decreased reporter gene expression, suggesting decreased levels of interaction, while Asp-85 for Gly mutation caused a higher level of expression, suggesting increased interaction. Among these point mutations, G85D, M102T, or D141V mutations were introduced into the gamma subunit gene in the plasmid carrying whole unc operon. Transformants carrying a deletion mutant of the whole unc operon with these expression plasmids were analyzed. Mutations M102T and D141V with decreased gamma-epsilon interaction caused increases of membrane-bound F1-ATPase activity and proton pumping activity, while G85D with increased gamma-epsilon interaction exhibited lower levels of F1-ATPase activity in the membranes. Molecular assembly of the F1 subunits on the mutant membranes detected by Western blotting exhibited no defect for all three mutants. These results suggested that the correlation between the ATPase activity and gamma-epsilon interaction is reciprocal and this interaction may regulate the ATPase activity. The topological and functional importance of Gly-85, Met-102, and Asp-141 together with Leu-55 and Leu-235 in gamma-epsilon interaction is discussed.

Amino Acid Substitution↗

PubMed1997

Interaction of the delta and b subunits contributes to F1 and F0 interaction in the Escherichia coli F1F0-ATPase.

Interactions of the F1F0-ATPase subunits between the cytoplasmic domain of the b subunit (residues 26-156, bcyt) and other membrane peripheral subunits including alpha, beta, gamma, delta, epsilon, and putative cytoplasmic domains of the a subunit were analyzed with the yeast two-hybrid system and in vitro reconstitution of ATPase from the purified subunits as well. Only the combination of bcyt fused to the activation domain of the yeast GAL-4, and delta subunit fused to the DNA binding domain resulted in the strong expression of the beta-galactosidase reporter gene, suggesting a specific interaction of these subunits. Expression of bcyt fused to glutathione S-transferase (GST) together with the delta subunit in Escherichia coli resulted in the overproduction of these subunits in soluble form, whereas expression of the GST-bcyt fusion alone had no such effect, indicating that GST-bcyt was protected by the co-expressed delta subunit from proteolytic attack in the cell. These results indicated that the membrane peripheral domain of b subunit stably interacted with the delta subunit in the cell. The affinity purified GST-bcyt did not contain significant amounts of delta, suggesting that the interaction of these subunits was relatively weak. Binding of these subunits observed in a direct binding assay significantly supported the capability of binding of the subunits. The ATPase activity was reconstituted from the purified bcyt together with alpha, beta, gamma, delta, and epsilon, or with the same combination except epsilon. Specific elution of the ATPase activity from glutathione affinity column with the addition of glutathione after reconstitution demonstrated that the reconstituted ATPase formed a complex. The result indicated that interaction of b and delta was stabilized by F1 subunits other than epsilon and also suggested that b-delta interaction was important for F1-F0 interaction.

Bacterial Proteins↗

PubMed1997

Exchangeability of the b subunit of the Cl(-)-translocating ATPase of Acetabularia acetabulum with the beta subunit of E. coli F1-ATPase: construction of the chimeric beta subunits and complementation studies.

The gene encoding the b subunit of the Cl(-)-translocating ATPase (aclB) was isolated from total RNA and poly(A)+ RNA of Acetabularia acetabulum and sequenced (total nucleotides of 3038 bp and an open reading frame with 478 amino acids). The deduced amino acid sequence showed high similarity to the beta subunit of the F type ATPases, but was different in the N-terminal 120 amino acids. The role of the N-terminal region was investigated using an F -ATPase beta-less mutant of E. coli, JP17. The JP17 strain expressing the aclB could not grow under conditions permitting oxidative phosphorylation, although ACLB was detected in the membrane fraction. The beta subunit was divided into three portions: amino acid position from 1 to 95 (portion A), 96 to 161 (portion B) and 162 to the C-terminus (portion C). The corresponding regions of ACLB were designated as portions A' (from 1 to 106), B' (from 107 to 172) and C' (from 173 to 478). Chimeric proteins with combinations of A-B'-C', A-B-C' and A'-B-C restored the function as the beta subunit in E. coli F0F1-complex, but those with combinations of A'-B'-C and A-B'-C had no function as the beta subunit. These findings suggested that portion B plays an important role in the assembly and function of the beta subunit in the F0F1-complex, while portion B' of ACLB exhibited inhibitory effects on assembly and function. In addition, portion A was also important for interaction of the beta subunit with the alpha subunit in E. coli F0F1-complex. These findings also suggested that the b subunit of the Cl(-)-translocating ATPase of A. acetabulum has a different function in the Cl(-)-translocating ATPase complex, although the primary structure resembled to the beta subunit of the F1-ATPase.

Acetabularia↗

PubMed1997

Escherichia coli F1-ATPase subunit interactions: beta and gamma subunit peptides inhibit in vitro reconstitution of the active alpha beta gamma complex.

For biochemical analysis of subunit interactions in the proton-translocating ATPase, a new approach with in vitro reconstitution of the Escherichia coli alpha beta gamma complex and the peptides derived from the subunits was established. Various portions of the beta or gamma subunits were used for in vitro reconstitution of the alpha beta gamma complex from the purified subunits. For the beta subunits, peptides corresponding to residues 226-459, 254-459, and 226-365 inhibited reconstitution, while those corresponding to residues 1-105, 1-146, and 295-459 did not. For the gamma subunits, peptides corresponding to residues 1-192 and 74-286 exhibited inhibitory effect on reconstitution, but the peptide containing residues 191-286 did not. Only inhibitory peptides blocked the assembly of the alpha beta gamma complex which was detected by nondenaturing polyacrylamide gel electrophoresis. These inhibitory peptides bound to the alpha or beta subunit on the filter, but the noninhibitory peptides did not. These results suggested that regions beta 254-294 and gamma 74-190 have sequences important for subunit interactions which interfered with those in the reconstitution mixtures. Based on comparison between X-ray crystallographic data of bovine alpha beta gamma complex and the present results, we discussed here the significance of the biochemical approach adopted in this study.

Circular Dichroism↗

PubMed1997

Temperature-responsive liquid chromatography. 2. Effects of hydrophobic groups in N-isopropylacrylamide copolymer-modified silica.

We recently reported the new concept of temperature-responsive liquid chromatography using temperature-responsive poly(N-isopropylacrylamide)-modified surfaces as high-performance liquid chromatography media with aqueous mobile phases. Incorporation of hydrophobic sites is an important factor to improve the efficacy (selectivity and retention) of temperature-responsive chromatography. Toward this goal, we have synthesized semitelechelic copolymers of N-isopropylacrylamide (IPAAm) and butyl methacrylate (BMA) having reactive terminal functional groups using telomerization. The lower critical solution temperatures of the copolymers shift to lower temperatures with increasing hydrophobic BMA content in the poly(IPAAm-co-BMA) relative to that of the IPAAm homopolymer. This temperature-responsive semitelechelic copolymer was grafted to the surface of (aminopropyl)silica through the reaction of activated ester-amine coupling. The polymer-modified silica was used as a column packing material. Separation of a mixture of five steroids having various hydrophobicities was investigated. Retention of steroids on poly(IPAAm-co-BMA)-modified columns is increased with an increase in column temperature. The capacity factors for steroids on the copolymer-modified silica beads was much larger than that on homopolymer PIPAAm-modified columns. The capacity factor for testosterone at 50 degrees C was 33.8 for poly(IPAAm-co-BMA) containing 5 mol% BMA, while that for the PIPAAm homopolymer was 15.0 at the same temperature. The influence of column temperature on steroid retention behavior on copolymer-modified stationary phases was significant compared with the case of homopolymer-modified columns. Furthermore, retention times for steroids increased remarkably with increasing BMA composition. The temperature-responsive elution behavior for the steroids was strongly affected by the hydrophobicity of the grafted polymer chains on silica surfaces. Possible protein separation in temperature-responsive liquid chromatography was explored using insulin chains A and B, and beta-endorphin fragment 1-27. On IBc-3.2-modified silica column, these three peptides were successfully separated at 30 degrees C with 0.5 M NaCl aqueous solution (pH 2.1) as mobile phase. The retention times of these peptides were related to the number of hydrophobic amino acid residues in the peptides. In the proposed chromatography system, elution of target substances is controlled only by a small change in column temperature without any further modification of the aqueous mobile phase.

Acrylamides↗

PubMed1997

Determination of peptides by high-performance liquid chromatography with laser-induced fluorescence detection.

Peptides were determined by high-performance liquid chromatography (HPLC) with laser-induced fluorescence detection. Detection was based on pre-column fluorescence derivatization of peptides with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) in acetonitrile (MeCN)-0.1 M borate buffer (pH 8.0) at 40 degrees C for 10 min. The peptide derivatives were separated on a reversed-phase column with trifluoroacetic acid-MeCN and determined fluorometrically at 530 nm with excitation at 470 nm. The method was applied to the determination of enkephalins in rat brain and to a degradation study of bradykinin in human plasma. Optimization of the reaction conditions and the use of a semi-micro-column (100 x 2 mm I.D., 2 microns) made the detection limit of the peptides as low as 5-10 fmol. The detection limits of enkephalin and bradykinin were 20 and 5 fmol, respectively, using HPLC with laser-induced fluorescence detection. The method was sensitive enough to permit the quantitative determination of opioid peptides and bradykinin in tissue and plasma samples.

4-Chloro-7-nitrobenzofurazan↗

PubMed1997

Catalytic and structural importance of Gly-454, Tyr-455, and Leu-456 in the carboxy-terminal region of Escherichia coli F1-ATPase alpha subunit.

Monoclonal antibody alpha110 recognizes Leu-456 in the alpha subunit of the Escherichia coli F1-ATPase. Binding of this antibody to the alpha subunit or mutation of this residue to Pro caused enhancement of the ATPase activity, suggesting that this residue is involved in the catalytic mechanism of this molecule (H. Kanazawa et al. (1995) Arch. Biochem. Biophys. 317, 348-356). Leu-456 together with Gly-454 and Tyr-455 are the only residues in the carboxy-terminal 75 amino acids conserved among various species, suggesting that these three residues play important roles in catalysis by the ATPase. Here, we introduced site-directed mutations into these residues. Not only L456P but also G454L, Y455K, Y455L, and L456N mutations caused enhancement of the ATPase activity. Surprisingly, Y455V, L456H, and L456S caused assembly defects of F1 subunits on the membrane. Reconstitution of the alpha betagamma complex from the wild-type beta and gamma subunits with the mutant alpha subunit (L4gamma6P) exhibited enhanced ATPase activity. Addition of delta or epsilon fused to glutathione S-transferase which are functionally similar to the delta and epsilon subunits, respectively, to the reconstituted F1-ATPase did not cause significant enhancement of its activity. Decreased interaction between alpha and beta subunits with the L456P mutation was detected by the yeast two-hybrid system. According to the deduced three-dimensional structure of the bovine a subunit, Leu-456, Gly-454, and Tyr-455 are included in a small alpha helix. These results suggest that this alpha helix affects interaction of the alpha subunit with the beta subunit but not with delta or epsilon, which may be important for the catalytic mechanism and F1 assembly.

Amino Acid Sequence↗

PubMed1997

Closure of a ventricular septal defect in a patient with von Willebrand disease.

Few reports of open heart surgery being performed in patients with von Willebrand disease (vWD) have been documented. We describe herein the case of a 5-year-old girl with a ventricular septal defect (VSD) and vWD who underwent patch closure under cardiopulmonary bypass (CPB). The hematological parameters relating to vWD, namely, factor VIII, von Willebrand factor, and factor VIII-related antigen were monitored perioperatively. These laboratory findings were elevated after the termination of CPB, and consistently maintained within the normal range for 4 months postoperatively. The operation was successfully completed without the administration of factor VIII concentrates or homologous blood products.

Cardiopulmonary Bypass↗

PubMed1997

Increased levels of nitric oxide derivatives in induced sputum in patients with asthma.

BACKGROUND: Nitric oxide (NO) plays an important role as an inflammatory mediator in the airways. However, because direct measurement of endogenous NO has been difficult in vivo, the exact pathologic roles of NO in human airway inflammation have remained unclear. OBJECTIVE: This study was designed to determine whether NO may be harmful by amplifying allergic inflammation in asthmatic airways. METHODS: In this study we examined the concentration of stable end products of NO, nitrite and nitrate, in induced sputum in 18 patients with asthma and 10 normal control subjects and evaluated the relationship between levels of NO derivatives in sputum and cellular and biochemical profiles, the degree of airflow obstruction, and the cytotoxic activities for epithelial cells. RESULTS: The concentration of NO derivatives in induced sputum was significantly higher in patients with asthma than in normal control subjects (1086 +/- 325 mumol/L, 577 +/- 115 mumol/L; p < 0.05). Percentages of eosinophil counts and eosinophil cationic protein levels in sputum were also significantly higher in patients with asthma. Moreover, percentages of eosinophil counts and eosinophil cationic protein levels in sputum in patients with asthma were significantly correlated with the concentration of NO derivatives in sputum (r = 0.63, p < 0.01; r = 0.56, p < 0.05, respectively). In addition, we found that the concentration of NO derivatives in sputum in patients with asthma was significantly correlated with the degree of airflow obstruction (FEV1/forced vital capacity) (r = -0.62, p < 0.01) and with percentages of shedding epithelial cells (r = 0.61, p < 0.01). CONCLUSION: We have shown that a higher concentration of NO derivatives was found in induced sputum of patients with asthma as compared with normal subjects. The clinical implication of our findings is that measurement of NO derivatives in induced sputum may be useful for assessing allergic inflammation in airways.

Adult↗

PubMed1997

Analysis of peptides and proteins by temperature-responsive chromatographic system using N-isopropylacrylamide polymer-modified columns.

A new method of HPLC using packing materials modified with a temperature responsive polymer, poly(N-isopropylacrylamide) (PIPAAm), was developed. Homogeneous PIPAAm polymer and its copolymer with butyl methacrylate (BMA) were synthesized and grafted to aminopropyl silica by activated ester-amine coupling and they were used as packing materials. The surface properties and functions of the stationary phases are controlled by external temperature. Isocratic elution by aqueous mobile phase alone is the basis for separation of peptides and protein. The separation of the mixture of three peptides, insulin chain A and B and beta-endorphin fragment 1-27 was achieved by changing the column temperature with 0.9% NaCl aqueous solution as the sole eluent. Retention of peptides and proteins was controlled both by column temperature and by NaCl concentration in the aqueous mobile phases in this chromatographic system.

Acrylamides↗

PubMed1997

Gin4 of S. cerevisiae is a bud neck protein that interacts with the Cdc28 complex.

BACKGROUND: A number of proteins make up the Cdc28 complex in Saccharomyces cerevisiae, and regulate CDK activity. The cell cycle regulator Nik1 (Hsl1) is a protein kinase that interacts with the Cdc28 complex. The growth inhibitor Gin4 is structurally similar to Nik1 and may play a redundant role in the regulation of the cell cycle. We investigated the functions of Gin4 with respect to those of Nik1. RESULTS: GIN4 was not essential for growth, and cells deficient in the GIN4 gene displayed no obvious defects in cell cycle regulation. The delta(gin)4 delta(nik)1 strain was temperature sensitive and showed an abnormal cell shape and FACS profile at permissive temperatures. GFP-fused Gin4 was localized at the bud-neck from late G1 to the M phase. Over-production of the C-terminal portion of Gin4 was toxic for cell growth, and this domain was required for the bud-neck localization of Gin4-GFP. High copy expression of Gin4-GFP disturbed the bud-neck localization of Gin4 in the abnormally elongated cells. Cytokinesis was defective in the delta(gin)4 cdc28 double mutants. The GST-Gin4 fusion protein physically associates with the Cdc28 complex. CONCLUSIONS: Gin4 is a bud-neck protein. GIN4 and NIK1 have distinct but partially overlapping functions. The major function of GIN4 is to ensure proper mitotic progression and cytokinesis.

Amino Acid Sequence↗

PubMed1997

Identification and characterization of functional residues in a Na+/H+ antiporter (NhaA) from Escherichia coli by random mutagenesis.

Forty-one mutants were isolated by means of random PCR mutagenesis of the Escherichia coli Na+/H+ antiporter (nhaA), which could not support the growth of a nhaAnhaB mutant (HIT delta AB-) on plates containing 0.15 M LiCl (pH 7.5) or 0.65 M NaCl (pH 8.0). Most of the mutants were sensitive to both NaCl and LiCl, or to LiCl alone. DNA sequencing revealed that twelve of the mutants had single amino acid substitutions. All the mutations, except for H225P, were of the conserved residues of NhaA homologues and located in the putative transmembrane helices. The Na+/H+ and Li+/H+ antiporter activities of the mutant NhaA were measured with everted membrane vesicles: eight of the mutants lost both antiporter activities completely under all pH conditions examined. Although both D133A and L138P retained low Li+/H+ antiporter activity, D133A lost Na+/H+ antiporter activity, while L138P retained normal Na+/H+ antiporter activity at pH 7.0 and 8.0. Interestingly, at pH 8.5, L138P no longer showed any Li+/H+ antiporter activity. H225P retained relatively high antiporter activities, although their pH dependence was altered. These observations supported the previous indication that His-225 is part of the pH sensor [Gerchman, Y. et al. (1993) Proc. Natl. Acad. Sci. USA 90, 1212-1216]. L73R exhibited about 20% each of the activities only at pH 8.0, and showed a similar pH dependence to H225P in both Na+/H+ and Li+/H+ antiport. Therefore, in addition to His-225, Leu-73, and/or its vicinity may also contribute to the pH sensing.

Amino Acid Sequence↗

PubMed1997

PAMP is a novel inhibitor of the tachykinin release in the airway of guinea pigs.

Proadrenomedullin NH2-terminal 20 peptide (PAMP), a newly identified hypotensive peptide, may play physiological roles in airway and cardiovascular controls. This study was designed to determine the mechanism responsible for the bronchoprotective effects of PAMP on capsaicin-induced bron-choconstriction in anesthetized guinea pigs. PAMP (10(-8)-10(-6) M) significantly inhibited capsaicin-induced bronchoconstriction in a dose-dependent manner. The bronchoprotective effect of PAMP (10(-6) M) was as large as that of isoproterenol (10(-7) M) and lasted > 10 min. The concentration of immunoreactive substance P (SP) in bronchoalveolar lavage fluid after administration of capsaicin (4 x 10(-6) M) was 120 +/- 10 fmol/ml. PAMP significantly inhibited the release of immunoreactive SP in a dose-dependent manner (60 +/- 6 fmol/ml for (10(-6) M PAMP, P < 0.01; 84 +/- 6 fmol/ml for 10(-7) M PAMP, P < 0.01; and 95 +/- 6 fmol/ml for 10(-8) M PAMP, P < 0.05). PAMP (10(-6) M) did not significantly affect exogenous neurokinin A (NKA) or NKA + SP-induced bronchoconstriction, whereas isoproterenol (10(-7) M) significantly inhibited exogenous tachykinin-induced bronchoconstriction. These findings suggest that the bronchoprotective effects of PAMP are mainly due to inhibition of the release of tachykinins at airway C-fiber endings.

Adrenomedullin↗

PubMed1997

Adenosine modulates endothelin-induced bronchoconstriction in guinea pig airway.

The present study was designed to determine whether endogenous and exogenous adenosine modulates endothelin (ET)-induced bronchoconstriction. Exogenous adenosine enhances ET-induced bronchoconstriction. Following pretreatment with adenosine deaminase and theophylline to eliminate or antagonize endogenous adenosine, ET-1-induced bronchoconstriction was significantly attenuated, but not that of ET-3. In conclusion, this is the first report of an enhancement of ET-induced bronchoconstriction of guinea pig airways by endogenous and exogenous adenosine. Our findings may be useful in designing specific adenosine receptor antagonists as therapeutic agents in the management of bronchial asthma.

Acetylcholine↗

PubMed1997

Synergistic effect of nitric oxide and vasoactive intestinal peptide on bronchoprotection against histamine in anesthetized guinea pigs.

Vasoactive intestinal peptide (VIP) and nitric oxide (NO) are considered to be nonadrenergic, noncholinergic (NANC) inhibitory neurostransmitters in the airways. It seems likely that these neurotransmitters may be coreleased and act as functional antagonists against bronchoconstrictor stimuli. In the present study, we examined the synergistic effect of NO and VIP on bronchoprotection against histamine in anesthetized guinea pigs. The NO donor, S-nitroso-N-acetylpenicillamine (SNAP) significantly inhibited histamine-induced bronchoconstriction in a dose-dependent manner. VIP also inhibited histamine-induced bronchoconstriction in a dose-dependent manner, but this bronchoprotective effect was short-lived. Additionally, VIP (10(-9) M) had no significant bronchoprotective effect, but a subthreshold dose of SNAP (10(-7) M) significantly potentiated VIP (10(-9) M)-induced bronchoprotection against histamine. Moreover, SNAP (10(-7) M) significantly enhanced VIP (10(-7) M)-induced bronchoprotection for a longer period of time. On the other hand, VIP (10(-9) M) also significantly potentiated SNAP-induced bronchoprotection against histamine. In conclusion, combination therapy with NO donor and VIP receptor agonist may have important advantages in the treatment of bronchial asthma, and both NO and VIP may contribute in complementary fashion to the NANC-induced relaxant response in guinea pig airways.

Anesthesia↗

PubMed1997

Occurrence of subtypes of gustatory cells in cat circumvallate taste buds.

Transmission-electron microscopy of cat taste buds confirmed that, as in other mammals, each taste bud comprised four distinct types of cells: Type I, Type II, Type III (gustatory), and Type IV (basal) cells. Gustatory cells made synaptic contacts with nerves to which synaptic vesicles were gathered. The following are the main findings on the cat gustatory cells: 1) The synaptic vesicles of gustatory cells were essentially all dense-cored in type; small clear vesicles, which usually are intermingled in other mammals, could not be found. 2) The vesicles were accumulated not only in the synaptic area but also in the basal cytoplasm. This implies endocrine and paracrine functions. 3) On the basis of the fine structure of the vesicles, two subtypes of gustatory cells were discriminated. A large part of the cells contained vesicles measuring about 180 nm in diameter, while a small part had smaller ones of about 100 nm in diameter. This is the first demonstration of a dual population of gustatory cells in mammals, suggesting different messenger substances utilized.

Animals↗