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Biomedical subjects

Y Kitano

Publications and source records attributed to Y Kitano.

At least 19 recordsLinked to original sources

Benzylic intermolecular carbon-carbon bond formation by selective anodic oxidation of dithioacetals.

[reaction: see text]. Novel anodic intermolecular carbon-carbon bond formation has been accomplished by the oxidative carbon-sulfur bond fission of benzylic dithioacetals to give a wide variety of aromatic compounds. The substitution reaction successfully took place by the selective anodic oxidation of a sulfur atom of a dithioacetal. Stepwise double-substitution reactions were also achieved by the regulation of oxidation potential.

Acetals↗

Pretreatment with topical all-trans-retinoic acid is beneficial for wound healing in genetically diabetic mice.

OBJECTIVE: Topical pretreatment with aIl-trans-retinoic acid (atRA) is known to improve healing of cutaneous wounds. We tested the effect of atRA on wound healing of genetically diabetic db/db mice. It is known that cutaneous wounds of db/db mice show delayed wound healing due to impaired wound contraction, delayed granulation tissue formation and underexpression of keratinocyte growth factor (KGF). METHODS: 0.1% atRA in 100 mg aqueous gel was applied to the back skin of db/db mice as well as to their normal heterozygous littermates, db/+ mice, for five consecutive days, and 2 days after completion of the atRA treatment, two round excisional wounds were created down the panniculus carnosus with a 6-mm punch biopsy on the back skin of each mouse. RESULTS: After 5 days treatment with 0.1% atRA, significant hypertrophy of the epidermis and dermis, neovascularization, and inflammatory cell invasion were seen in the skin of the db/db mice, but these effects were seen only weakly in db/+ mice. Wounds in atRA-treated db/db mice closed more rapidly than those in vehicle-treated db/db mice. KGF mRNA expression, which is usually significantly lower in db/db mice than in normal mice, in wounds of atRA-treated db/db mice on day 1 of treatment was as strong as in db/+ mice. CONCLUSION: Pretreatment with atRA reversed the impaired wound healing in db/db mice.

Administration, Topical↗

Single vaginal ectopic ureter and renal hypoplasia associated with urogenital sinus and abdominal muscular hypoplasia-a novel subtype of prune-belly syndrome in a female child?

We report a rare case that can be classified as prune-belly syndrome in a female. This patient came to our attention during the 19th week of gestation when massive ascites was found by ultrasound and the mother was transferred to our hospital. After birth, it was demonstrated that the infant had complicated anomalies, including abdominal muscular hypoplasia, urogenital sinus, a single, right-sided vaginal ectopic ureter, and hypoplasia of the right kidney. A sibling had a right hypoplastic kidney and right vesicoureteral reflux. Considering the combination of anomalies and the family history of urinary tract disease, her anomalies could be attributed to a genetic mutation.

Choristoma↗

Effects of all-trans retinoic acid on melanogenesis in pigmented skin equivalents and monolayer culture of melanocytes.

The effects of all-trans retinoic acid (RA) on melanogenesis and the mechanism of its action in topical treatment have not been elucidated. The purpose of this study was to determine the effects of RA on melanogenesis in the pigmented skin equivalent as well as in monolayer culture of melanocytes, and to determine whether RA, hydroquinone (HQ), and hydrocortisone (HC) show synergistic depigmenting effects in combined treatments of each other. The suppressing effect of RA on melanogenesis was not observed in pigmented skin equivalents and monolayer culture of murine and human melanocytes, although HQ showed strong inhibition of melanogenesis. The synergistic effects between RA, HQ, and HC were not particularly seen. The results suggested that RA neither has direct inhibitory effects on melanogenesis of melanocytes, nor influences the cell-cell interactions between melanocytes, keratinocytes and fibroblasts, such as paracrine actions with regard to melanin production. The role of RA in bleaching treatments appears to be in other specific actions, such as promotion of keratinocytes proliferation and acceleration of epidermal turnover.

Animals↗

Synthesis of variously oxidized abietane diterpenes and their antibacterial activities against MRSA and VRE.

Variously oxidized 12 natural abietanes, 6,7-dehydroferruginol methyl ether (3), ferruginol (5), 11-hydroxy-12-oxo-7,9(11),13-abietatriene (7), royleanone (9), demethyl cryptojaponol (12), salvinolone (14), sugiol methyl ether (16), sugiol (17), 5,6-dehydrosugiol methyl ether (19), 5,6-dehydrosugiol (20), 6beta-hydroxyferruginol (23), and taxodione (25) were synthesized. Antimicrobial activities of synthesized phenolic diterpenes and their related compounds against MRSA and VRE were evaluated. Phenols (12-hydroxyabieta-8,11,13-trien-6-one 22 and 23), catechols (12 and 14) and taxodione 25 showed potent activity with 4-10 microg/mL of MIC against MRSA and 4-16 microg/mL of MIC against VRE. (-)-Ferruginol showed more potent activity than natural type (+)-ferruginol. Quinone methide 7 showed the most potent activity with 0.5-1 microg/mL of MIC against both MRSA and VRE.

Anti-Bacterial Agents↗

Effect of procainamide on the postrepolarization refractoriness in cardiac muscle: evaluation using the block coupling interval in the artificial isthmus model in the canine right atrium.

The post-repolarization refractoriness (PRR) is an important factor to determine the conduction block in cardiac muscle. Recently, we proposed the block coupling interval (BCI) as an useful electrophysiological index for evaluating the PRR. In the present study, the effect of procainamide on PRR was evaluated using the BCI and the effective refractory period (ERP). In five beagle dogs, radiofrequency linear ablation was performed on the right atrial surface parallel to the AV groove, forming an artificial isthmus (8-10 mm width and 15-20 mm length). Bipolar recordings were performed in the isthmus at a resolution of 1.2 mm and single extrastimuli with eight basic drive trains were delivered to cause conduction blocks in the isthmus. When a conduction block occurred, the recorded coupling interval at the recording site just proximal to the site of block was defined as BCI. At the site of the block, the ERP and duration of the monophasic action potential (MAP) at each drive cycle length was measured. The PRR was calculated using two different formulas: (1) [ERP-MAP] and (2) [BCI-MAP]. Procainamide was administrated intravenously at a dose of 15 mg/kg after the control study and the whole study protocol was repeated. The site of the block in an individual dog was always the same. BCI, ERP, and MAP were all shortened in accordance with the shortening of the basic drive cycle length, and the BCI was always the longest, ERP the middle, and the MAP was the shortest. The administration of procainamide prolonged each parameter, but the order of BCI > ERP > MAP remained unchanged. The PRR calculated as [BCI-MAP] was prolonged from 15 +/- 10 ms to 29 +/- 8 ms by the administration of procainamide (P = 0.048), but [ERP-MAP] was unchanged (8 +/- 10 ms vs 8 +/- 4 ms). In the conduction block model in the canine right atrium, procainamide prolonged the [BCI-MAP], but did not change the [ERP-MAP]. The procainamide effect of prolonging the PRR might be expressed better by the change in the BCI than the ERP.

Animals↗

BAPS prize-1999: Lung growth induced by prenatal tracheal occlusion and its modifying factors: a study in the rat model of congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Prenatal tracheal occlusion (TO) has been shown to accelerate lung growth in animal models and models of pulmonary hypoplasia. However, these models may not mimic early events in human congenital diaphragmatic hernia (CDH). The authors previously have developed a model of TO in the rat. The purpose of this study was to apply this technique to characterize TO-induced lung growth in the early onset nitrofen-induced model of CDH, and to address the clinically important questions of the effect of timing of TO and maternal infusion of terbutaline on TO-induced lung growth. METHODS: Left-sided CDH was induced in the fetuses of time-dated pregnant Sprague-Dawley rats by feeding 100 mg of nitrofen on day 9 of gestation. TO was performed via maternal laparotomy and hysterotomy at 19 days' gestation. At harvest (21.5 days' gestation), lungs from nitrofen-exposed fetuses without CDH (non-CDH), with CDH (CDH), and with CDH and TO (CDH-TO) were compared by analysis of wet and dry weight, DNA and protein content, and stereologic morphometry. A second study was performed to assess relative lung growth achieved by equal intervals of TO after "early" (19 days) versus "late" (20 days) gestational TO. Finally, the effect of maternal infusion of terbutaline, a commonly used tocolytic for fetal surgery, on TO-induced lung growth was analyzed. RESULTS: Analysis of lung growth showed consistent and significant lung growth in CDH-TO lungs. Lung growth after TO was proliferative and characterized by an increase in parenchymal volume as manifest by increased total saccular number and surface area and radial saccular count. Although visceral reduction was partially achieved, herniated liver was reduced incompletely. The majority of lung growth occurred during the latter half of the TO period. Early gestational age at TO and maternal terbutaline administration adversely influenced lung growth in CDH-TO fetuses. CONCLUSIONS: Prenatal TO induces dramatic lung growth in the early onset, nitrofen-induced rat model of CDH. TO is more effective later in gestation presumably because of the advanced stage of lung development and lung fluid production. This effect could be counterbalanced by the use of beta-mimetic tocolytic, which inhibits fetal lung fluid production late in gestation. Multiple factors including fetal lung fluid production and absorption, pharmacologic agents, space-occupying herniated viscera, and timing and duration of TO may be important clinical variables. The development of the rat model should facilitate further studies into the cellular and molecular mechanisms responsible for TO-induced lung growth.

Animals↗

Fetal tracheal occlusion in the rat model of nitrofen-induced congenital diaphragmatic hernia: tracheal occlusion reverses the arterial structural abnormality.

BACKGROUND/PURPOSE: The high mortality rate of congenital diaphragmatic hernia (CDH) is ascribed generally to pulmonary hypoplasia and persistent pulmonary hypertension characterized by associated pulmonary arterial structural changes. Prenatal tracheal occlusion (TO) accelerates lung growth, but the effect of TO on pulmonary arterial structure in CDH has not been well defined. The authors hypothesized that TO could reverse the pulmonary arterial structural changes observed in CDH. To address this hypothesis, we utilized the nitrofen-induced rat model of CDH to examine the effect of TO on pulmonary arterial morphology of CDH lungs. METHODS: Left-sided CDH was induced by administering 100 mg of nitrofen to pregnant Sprague-Dawley rats on day 9 of gestation. TO was performed on day 19, and the fetuses were harvested on day 21.5 of gestation. After the ductus arteriosus was ligated, the pulmonary arteries were injected with a barium-gelatin mixture, and the lungs were inflation fixed. Coronal sections of the lungs were stained with elastin van Gieson. External diameter (ED), internal diameter (ID), and medial and adventitial wall thickness of the pulmonary arteries were measured using a computer image analyzer, and the percent medial thickness (%MT) and adventitial thickness (%AT) were calculated. The lungs from nitrofen-exposed fetuses with left-sided CDH (CDH group), trachea-occluded left-sided CDH (CDH+TO group), non-CDH (non-CDH group), and normal fetuses (normal group) were compared. RESULTS: The %MT was significantly increased in all sizes of arteries in CDH compared with non-CDH and normal groups (P < .01). Compared with the CDH group, the CDH+TO group had significantly reduced %MT in all sizes of arteries (P < .01), to values comparable or less than the non-CDH and normal groups. The %AT of the CDH group was significantly increased in larger arteries compared with non-CDH and normal control groups (P < .01). CDH+TO had significantly decreased %AT compared with CDH in both larger (P < .01), and smaller arteries (P < .05) and that was comparable with the non-CDH and normal control groups. CONCLUSIONS: TO in hypoplastic CDH lung can reverse the pulmonary arterial structural changes that are seen in the nitrofen-induced fetal rat model of CDH. These data suggest that TO may reduce pulmonary vascular reactivity, and the risk of postnatal persistent pulmonary hypertension observed in human neonates with severe CDH. J Pediatr Surg 36:839-845.

Analysis of Variance↗

Pulmonary epithelial cell maturation in hyperplastic lungs associated with fetal tracheal agenesis.

BACKGROUND/PURPOSE: Cellular differentiation of pulmonary hyperplasia has not been reported in human cases. The authors studied surfactant protein expression and ultrastructure of pulmonary epithelial cells in fetal hyperplastic lungs associated with congenital tracheal agenesis. METHODS: The maturation of pulmonary epithelial cells was assessed by immunohistochemical examination for surfactant proteins (SP-A, mature SP-B, proSP-B, proSP-C, and SP-D) and transmission electron microscopy. As controls normal lung portions of 8 fetuses born at 21 weeks gestation were used. RESULTS: Mature SP-B and SP-D was detected in terminal airways in this case, but not in controls. In electron microscopy, lamellar bodies were recognized, and glycogen granules were less abundant in terminal airway cells. CONCLUSION: The differentiation of pulmonary epithelial cells appeared to be more advanced for the gestational age in pulmonary hyperplasia with congenital tracheal agenesis. J Pediatr Surg 36:1845-1848.

Adult↗

Fetal lung growth after short-term tracheal occlusion is linearly related to intratracheal pressure.

Prenatal tracheal occlusion (TO) has been shown to accelerate fetal lung growth, yet the mechanism is poorly understood. The goal of this study was to determine the relationship between fetal intratracheal pressure (Pitr) and fetal lung growth after TO. Fetal lambs underwent placement of an intratracheal catheter and a reference catheter at 115--120 days gestation (term, 145 days). Fetal Pitr was continuously controlled at three levels (high, 8 mmHg; moderate, 4 mmHg; low, 1 mmHg) by a servo-regulated pump. The animals were killed after 4 days, and the parameters of lung growth were compared. Lung volume (136.0 +/- 16.7, 94.9 +/- 9.7, 55.5 +/- 12.4 ml/kg), lung-to-body weight ratio (6.31 +/- 0.70, 4.89 +/- 0.38, 3.39 +/- 0.22%), whole right lung dry weight (3.01 +/- 0.29, 2.53 +/- 0.15, 2.07 +/- 0.24 g/kg), right lung DNA (130.0 +/- 11.3, 116.7 +/- 8.6, 97.5 +/- 10.9 mg/kg), and protein contents (1,865.5 +/- 92.5, 1,657.6 +/- 106.8, 1,312.0 +/- 142.5 mg/kg) in high, moderate, and low groups, respectively, all increased in the moderate compared with the low group and increased further in the high compared with the moderate group. Morphometry confirmed a stepwise increase in the volume of respiratory region and alveolar surface area. We conclude that lung growth in the first 4 days after TO is closely correlated with fetal Pitr, offering additional evidence that an increase in lung expansion is one of the major factors responsible for TO-induced lung growth.

Animals↗

Leakage of energy to the body surface during defibrillation shock by an implantable cardioverter-defibrillator (ICD) system--experimental evaluation during defibrillation shocks through the right ventricular lead and the subcutaneous active-can in canines.

The leakage of electrical current to the body surface during defibrillation shock delivery by an implantable cardioverter-defibrillator (ICD) device (the Medtronic Jewel Plus PCD system) was evaluated in 5 dogs. The defibrillation shocks were delivered between the active-can implanted in the left subclavicular region and the endocardial lead placed in the right ventricle at the energy levels of 1, 2, 8, 12, 24 and 34 J. During each delivery, the electrical current leakage from the body surface was measured by electrodes connected to a circuit at 4 recording positions: (A) parallel-subcutaneous (the electrodes were fixed in the subcutaneous tissue of the left shoulder and the right lower chest, and the direction of the electrode vector was parallel to the direction of the defibrillation energy flow); (B) cross-subcutaneous (the electrodes were fixed in the subcutaneous tissue of the right shoulder and the left lower chest, and the vector of the electrodes was roughly perpendicular to the direction of the energy flow); (C) parallel-surface (the electrodes were fixed with ECG paste on the shaved skin surface at the left shoulder and the right lower chest); and (D) surface grounded (the electrodes were fixed on the shaved skin surface at the left shoulder and the left foot, which was grounded). The circuit resistance was set at a variable level (100-5,000 ohms) in accordance with the resistance measured through each canine body. Leakage energies were measured in 750 defibrillation shocks with each circuit resistance in 5 dogs. The leakage energy increased in accordance with the increase of the delivered energy and the decrease of the circuit resistance in all 4 recording positions. When the circuit resistance was set at 1,000 ohms, the leakage energy during shock delivery at 34 J was 32+/-17 mJ at position A, 5+/-9 mJ at B, 10+/-9 mJ at C, and 4+/-3 mJ at D (p=0.042). The peak current was highest at position A and was 87+/-22 mA with a circuit resistance of 1,000 ohms. The power of the leakage energy depended on the delivered energy and the impedance between the electrodes. The angle between the alignment of the recording electrodes and the direction of the energy flow was another important factor in determining the leakage energy. Although the peak current of the leakage energy reached the level of macro shock, the highest leakage energy from the body surface was considerably less because of the short duration of the shock delivery.

Animals↗

Inhomogeneity in the appearance of electrical remodeling during chronic rapid atrial pacing: evaluation of the dispersion of atrial effective refractoriness.

In the present study, the long-term process of progression of electrical remodeling at various atrial sites, which is not well understood, was compared while monitoring continuously the electrophysiologic parameters at multirecording sites in canine atria during continuous atrial burst pacing. A rapid pacing device was implanted in 5 dogs, and continuous atrial burst pacing (400 beats/min) was delivered at the right atrial appendage (RAA). Four pairs of epicardial wire electrodes were sutured on (1) the RAA, (2) Bachmann's bundle (BB), (3) the right atrium close to the inferior vena cava (IVC), and (4) the left atrium (LA). The distal ends of those wires were exteriorized posteriorly and used for pacing and recording. The atrial effective refractory period (AERP), AERP dispersion (AERPd), atrial conduction time (CT) and inducibility of atrial fibrillation (AF) were evaluated during burst pacing for 14 days and during the subsequent 7 days' recovery. The AERP at the LA pacing site was shorter than that at the other sites on day 0. The AERP shortening was greater in the RAA and LA sites than in the BB and IVC sites. The AERPd increased during pacing and reached the maximum level on day 3, and then decreased during the recovery phase. Prolongation of CT tended to be longer between the RAAand IVC sites than that between the other sites. The incidence of AF induction became higher in accordance with the time course of the rapid pacing phase. There was another peak of AF induction on days 7-10. In a canine chronic rapid atrial stimulation model, the progression of electrical remodeling (ie, the shortening of the AERP and the prolongation of the CT) was not homogeneous in both atria, the AERPd showed a temporal increase between days 3 and 7 and matched the increase in AF inducibility at the LA pacing site, the increase in the AERPd was mainly caused by more rapid AERP shortening at the RAA or LA sites, and the LA site always showed a shorter AERP than the other atrial sites in the control state and during the rapid pacing phase, whereas AF inducibility was higher at the LA site than the other sites.

Animals↗

Evaluation of post-repolarization refractoriness for conduction block in cardiac muscle: studies in an artificial isthmus in the canine right atrium.

Post-repolarization refractoriness (PRR) is an important factor in determining conduction block and is the difference between the effective refractory period (ERP) and the duration of the monophasic action potential (MAPD). In the present study, conduction block in an artificial isthmus in the canine atrium was evaluated and the coupling interval of a premature beat, which caused the block, was defined as the block coupling interval (BCI). The usefulness of this value was also evaluated. Radiofrequency linear ablation was performed on the right atrial surface parallel to the atrioventricular groove in 5 mongrel dogs, and an artificial isthmus (8-10mm wide and 25-30mm long) was created. Fourteen simultaneous unipolar recordings were performed in the isthmus with a resolution of 1.2 mm. Single extra-stimuli with basic drive train were delivered to induce conduction block in the isthmus and when it occurred, the coupling interval at the recording site just proximal to the site of the block was defined as the BCI. At the site of the block, the ERP and MAPD at each drive cycle length were measured. The PRR was calculated using 2 different formulae: (1) [ERP-MAPD], and (2) [BCI-MAPD]. It was found that each value was shortened in accordance with the shortening of the basic drive cycle length. In all basic drive trains, BCI>ERP>MAPD, and [ERP-MAPD] was always shorter than [BCI-MAPD]. In the shorter cycle length of basic drives, the difference between [ERP-MAPD] and [BCI-MAPD] was more prominent. In the artificial isthmus model in the canine atrium, BCI was always longer than the ERP measured at the same site as the block. Because the ERP may not directly reflect the block phenomenon, the electrophysiologic evaluation should use the BCI instead, as in the PRR evaluation.

Action Potentials↗

Clinical usefulness of the atrial double potential at the intercaval region in the right atrium: a new index for inducibility of atrial fibrillation in electrophysiologic studies.

The second deflection of the atrial double potential (DP) recorded at the intercaval region is considered to reflect the far-field potential of the left atrium. The conduction via the upper interatrial connection was evaluated utilizing this DP and the relationship between atrial fibrillation (AF) and the conduction via the interatrial connection evaluated. In 30 consecutive patients with the DP at the intercaval region, prolongation in the left atrial activation time during the right atrial extra stimulation was measured at the intercaval region (deltaDP) and the coronary sinus (deltaCS). The difference between deltaDP and deltaCS (deltaDP-deltaCS) was used as an index of inhomogeneity in interatrial conduction. The patients were divided into AF (n=13) and non-AF (n=17) groups in accordance with the inducibility of AF in the electrophysiologic study. The max deltaDP and the max ACS were greater in the AF group than in the non-AF group, i.e., max deltaDP (43+/-19 vs 27+/-17 ms, P=0.021), max deltaCS (35+/-15 vs 21+/-14 ms, P=0.029). The max absolute value(deltaDP-deltaCS) was also greater in t

Action Potentials↗

Human interferon-alpha induces immobility in the mouse forced swimming test: involvement of the opioid system.

In a previous study, we indicated that human interferon (IFN)-alpha (IFN-alpha, 6 x 10(4) IU/kg, i.v.), but not human IFN-beta or -gamma, prolonged the immobility time of the forced swimming test in mice. In this study, we investigated the mechanism of the effect of human IFN-alpha. None of the mouse IFNs tested (IFN-alpha/beta, IFN-beta, and IFN-gamma, 3 x 10(5) U/kg, i.v.) changed the immobility time or the spontaneous locomotor activity in mice. Indomethacin (10 mg/kg, s.c.), a cyclooxygenase inhibitor, did not affect the increase in the immobility time induced by human IFN-alpha (6 x 10(4) IU/kg, i.v.). However, naloxone (1 mg/kg, s.c.), an opioid receptor antagonist, blocked the increasing caused by human IFN-alpha in the forced swimming test. These results suggest that the increase in the immobility time caused by human IFN-alpha in the forced swimming test might be mediated through opioid receptors, but not mouse IFN receptors.

Animals↗

In vivo, in utero microscopic magnetic resonance imaging: application in a rat model of diaphragmatic hernia.

This article presents a microscopic MR technique for imaging small mammalian fetuses in utero and in vivo which can be used as a tool for studying normal and abnormal development in small animal fetal models, for targeting in utero intervention in such models, and for following development serially. This new method is applied to a rat model of congenital diaphragmatic hernia (CDH). Pregnant Sprague-Dawley rats were fed nitrofen at 9.5 days postcoitus to induce CDH in the fetuses. The dams were imaged to identify fetuses with CDH for targeted in utero intervention, which consisted of fetal tracheal ligation. Following tracheal ligation, the fetuses were followed serially with our MR technique. For MR imaging, the dam was anesthetized with intramuscular ketamine and intraperitoneal pentobarbital. In utero imaging was performed on a 4 Tesla MRI system using a multislice, fast spin echo sequence with a long TR and short effective TE. These results were validated by examining individual fetuses postmortem using high-resolution MR and anatomic dissection. The in utero, in vivo MR technique is highly accurate for diagnosing CDH and following the effects of surgical intervention, and shows promise as a tool for the study of embryogenesis in small animal models. Magn Reson Med 44:331-335, 2000.

Animals↗

Human interferon-alpha increases immobility in the forced swimming test in rats.

OBJECTIVES: We examined the immobility of the forced swimming test induced in an animal model by human interferon (IFN), which has often been reported to induce depression in clinical use. METHODS: In the present study, we examined the effects of human IFNs on results of the forced swimming test in rats. RESULTS: Single intravenous (IV) administration of human IFN-alpha (6x10(4) IU/kg), but not of human IFN-beta or -gamma, significantly increased immobility time in the forced swimming test in rats. Repeated administration of human IFN-alpha (6x10(3) IU/kg) also significantly increased the immobility time. On the other hand, none of the rat IFNs (rat IFN-alpha, -beta and -gamma, 6x10(4) IU/kg, IV) changed the immobility time. Neither human IFNs nor rat IFNs changed the locomotor activity of rats. CONCLUSIONS: These findings suggest that human IFN-alpha has a greater potential for inducing increase of the immobility in the rat forced swimming test than human IFN-beta and -gamma, and that the effect of human IFN-alpha might not be mediated through IFN-alpha/beta receptors.

Animals↗