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Biomedical subjects

Masatoshi Hori

Publications and source records attributed to Masatoshi Hori.

At least 19 recordsLinked to original sources

Evaluation of renal arteries in living renal donors: comparison between MDCT angiography and gadolinium-enhanced 3D MR angiography.

PURPOSE: The purpose of this study was to clarify and compare the accuracy of contrast-enhanced computed tomography (CT) angiography using multidetector-row helical CT (MDCT angiography) and gadolinium-enhanced MR angiography using three-dimensional Fourier transformation gradient-echo sequence (3D MR angiography) for preoperative evaluation of renal arteries in living renal donors. MATERIALS AND METHODS: A total of 42 living renal donor candidates underwent both MDCT angiography and 3D MR angiography before digital subtraction angiography (DSA). Each MDCT angiogram and 3D MR angiogram was prospectively interpreted, and the findings were compared with the DSA results. RESULTS: MDCT angiography identified all of the 12 supernumerary arteries detected by DSA, whereas 3D MR angiography identified only 8. MDCT angiography identified all of the 19 proximal arterial branches detected by DSA, whereas 3D MR angiography identified only 16. CONCLUSION: A more accurate depiction of renal arteries in living renal donors can be achieved with MDCT angiography than with 3D MR angiography.

Adult↗

Possible involvement of muscularis resident macrophages in impairment of interstitial cells of Cajal and myenteric nerve systems in rat models of TNBS-induced colitis.

Resident macrophages are distributed in the network of interstitial cells of Cajal (ICC) and the myenteric nerve within the myenteric plexus. We evaluated changes in chemoattractant protein mRNA expression in macrophages and neutrophils, the ICC, nerve and macrophages in the myenteric plexus of model rats with TNBS-induced colitis. Chemoattractant proteins, MCP-1, GRO, MIP-2 and CINC-2alpha were upregulated in the colonic muscle layer after inflammation. Leukocyte infiltration and MPO activity were increased in the muscle layer. Electron microscopy indicated an irregular contour of the myenteric ganglia into which numerous macrophages had penetrated. Macrophages were also distributed near the ICC in the inflamed myenteric plexus. Immunohistochemistry showed that the ICC network and myenteric nerve system had disappeared from the inflamed region, whereas the number of resident macrophages was increased. TTX-insensitive, possibly ICC-mediated, rhythmic contractions of circular smooth muscle strips and enteric neuron-mediated TTX-sensitive peristalsis in the whole proximal colon tissue were significantly inhibited in the inflamed colon, indicating that the ICC-myenteric nerve system was dysfunctional in the inflamed muscle layer. Their accumulation around the myenteric nerve plexus and the ICC network suggests that macrophages play an important role in inducing intestinal dysmotility in gut inflammation.

Animals↗

Interstitial cells of Cajal in dysmotility in intestinal ischemia and reperfusion injury in rats.

BACKGROUND: Intestinal ischemia and reperfusion (I/R) injury is an obligatory occurrence in small bowel transplantation. I/R may impair the normal gastrointestinal motility. Interstitial cells of Cajal (ICC) are known as pacemaker cells in the gastrointestinal tract. The aim of this study was to assess the role of ICC in the gastrointestinal motility in a rat model of I/R injury. MATERIALS AND METHODS: Wistar rats were subjected to 30- or 80-min intestinal ischemia by occluding the mesenteric vessels followed by reperfusion. Small intestinal segments were resected at 12 h or 4 days. The spontaneous mechanical activity was evaluated by organ bath technique. Immunopositivity of c-Kit and PGP9.5 at the level of the myenteric plexus was evaluated as markers of ICC and enteric nerves, respectively. RESULTS: In the bowel segment with 80-min ischemia followed by 12-h reperfusion, muscles showed a 25% reduction (P < 0.05) in the frequency of contractions compared to that with 30-min ischemia followed by 12-h reperfusion, whereas amplitude of contractions was not significantly different. This change was associated with a 70% decrease (P < 0.01) of c-Kit immunopositivity. These changes of intestinal motility pattern and distribution of c-Kit-positive cells were both recovered from 80-min ischemia followed by 4 days reperfusion. In contrast, the immunopositivity of PGP9.5 was not affected in any I/R injury group. CONCLUSIONS: Transient functional changes in ICC were induced by prolonged I/R injury but they recovered after 4 days, suggesting a central role of ICC in both disrupting and restoring the normal gastrointestinal motility in I/R injury.

Animals↗

Hepatic metastases: detection with multi-detector row CT, SPIO-enhanced MR imaging, and both techniques combined.

PURPOSE: To retrospectively compare the accuracy in detection of hepatic metastases among contrast material-enhanced multi-detector row computed tomography (CT) alone, superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging alone, and a combination of contrast-enhanced CT and SPIO-enhanced MR imaging. MATERIALS AND METHODS: The ethics committee did not require its approval or informed consent for this retrospective study, which was compliant with Declaration of Helsinki principles. Data in 38 patients (22 men, 16 women; mean age, 64.5 years; range, 35-78 years) suspected of having hepatic metastases who underwent both contrast-enhanced CT and SPIO-enhanced MR imaging were retrospectively analyzed. Twenty-one of the 38 patients had 61 metastases. Seventeen of the 61 metastases were confirmed histologically; the remaining 44 metastases were defined with imaging follow-up. At MR imaging, SPIO-enhanced heavily T1-weighted images, T2*-weighted gradient echo images, and T2-weighted fast spin-echo images were evaluated. Contrast-enhanced multi-detector row CT images obtained in the portal phase were evaluated. Four blinded observers independently reviewed CT images, MR images, and the combination of CT and MR images. Diagnostic accuracy was evaluated by using the alternative free-response receiver operating characteristic (AFROC) method. Sensitivities and positive predictive values were also analyzed with the Fisher protected least significant difference test and generalized estimating equations. RESULTS: The mean area under the AFROC curve for the combined approach (0.70) was significantly higher than that for SPIO-enhanced MR imaging alone (0.58, P < .05, Fisher protected least significant difference test), and there was no significant difference between each of them and that for contrast-enhanced CT alone (0.66). For all lesions, the mean sensitivity of combined imaging (0.59) was significantly higher than that of CT (0.48) or MR imaging (0.43) alone (P < .05, Fisher protected least significant difference test and generalized estimating equations). For all lesions, the mean positive predictive values were 0.82, 0.89, and 0.81, for combined MR and CT, CT alone, and MR alone, respectively. CONCLUSION: The addition of SPIO-enhanced MR imaging to contrast-enhanced multi-detector row CT (ie, combined analysis of SPIO-enhanced MR images and contrast-enhanced CT images) can improve sensitivity in the detection of hepatic metastases, although this improvement in sensitivity was not significant at AFROC analysis.

Adult↗

Fat in the liver: diagnosis and characterization.

The purpose of this article is to provide an update on imaging techniques useful for detection and characterization of fat in the liver. Imaging findings of liver steatosis, both diffuse steatosis and focal fatty change, as well as focal fatty sparing, are presented. In addition, we will review computed tomography (CT) and magnetic resonance (MR) findings of focal liver lesions with fatty metamorphosis, including hepatocellular carcinoma, hepatocellular adenoma, focal nodular hyperplasia, angiomyolipoma, lipoma, and metastases.

Diagnosis, Differential↗

Hemodynamic characterization of focal hepatic lesions: role of ferucarbotran-enhanced dynamic MR imaging using T2-weighted multishot spin-echo echo-planar sequence.

PURPOSE: To investigate the role of ferucarbotran-enhanced dynamic MR imaging using multishot spin-echo echo-planar sequence in the evaluation of hemodynamics of focal hepatic lesions. MATERIALS AND METHODS: Sixty-three focal hepatic lesions (24 benign and 39 malignant) from 53 consecutive patients who underwent both ferucarbotran-enhanced MR imaging and dynamic computed tomography (CT) were included in this study. MR imaging was performed with a 1.5-T scanner with a phased-array coil. T2-weighted multishot spin-echo echo-planar sequences (TR/TE = 1714-2813/80 msec) were obtained during a single breathhold before and 15, 60, 120, 180, and 600 seconds after intravenous injection of ferucarbotran. The enhancement patterns of lesions were classified into three categories by a study coordinator on the basis of dynamic CT images as hypervascular, hypovascular, and hemangioma type. The study coordinator created mean contrast-to-noise ratio of lesions vs. time curves for each enhancement pattern for quantitative analyses. Moreover, three radiologists separately and blindly reviewed MR images, and then assigned three confidence scores for the three enhancement patterns to each lesion. Sensitivity, specificity, and receiver operating characteristic analyses were performed. RESULTS: Quantitative analyses showed characteristic enhancement curves for each enhancement pattern. Mean sensitivities/specificities were 0.816/0.882, 0.897/0.863, and 0.800/0.989 for hypervascular, hypovascular, and hemangioma types, respectively. Mean areas under the receiver operating characteristic curve were 0.886 for hypervascular type and 0.913 for hypovascular type. CONCLUSION: Ferucarbotran-enhanced dynamic MR imaging can be used to successfully characterize the hemodynamics of focal hepatic lesions.

Adult↗

Principles and techniques of transcatheter embolotherapy for peripheral vascular lesions.

Transcatheter embolotherapy (TCE), a common procedure for interventional radiologists, comprises transcatheter delivery of embolic agents into target vessels in order to eliminate lesions or lesion-associated symptoms. Good knowledge of delivery catheters and embolic agents is essential to optimize embolization techniques and to obtain the desired therapeutic outcomes. In this review, we describe the principles and techniques of TCE for peripheral arterial and venous lesions featuring visceral aneurysms, peripheral and pulmonary arteriovenous malformations (AVMs), and varicoceles.

Catheterization↗

Up-regulation of NOD1 and NOD2 through TLR4 and TNF-alpha in LPS-treated murine macrophages.

NOD1 (Card4) and NOD2 (Card15) are thought to be responsible for cytoplasmic defense against bacterial entry. To gain further knowledge about how their expressions are regulated in murine macrophages, we investigated the expression of NOD1 and NOD2 mRNAs after stimulation with various endotoxins, lipopolysaccharide, lipoteichoic acid and peptidoglycan. In macrophage RAW264.7 cells, the first and second rises in NOD1 and NOD2 mRNAs were observed at 2 hr and at 8-12 hr after endotoxin treatment. Increases in NOD1 and NOD2 mRNAs at 2 hr in lipopolysaccharide-treated RAW264.7 cells were reduced with the use of NF-kappaB inhibitor, caffeic acid phenethyl ester. In RAW264.7 cells, lipopolysaccharide-induced increases in NOD1 and NOD2 mRNAs were inhibited with anti-TLR4 antibody, and partially reduced in peritoneal macrophages obtained from TLR4-deficient mice. Furthermore, NOD1 and NOD2 mRNA expressions in RAW264.7 cells were increased by the treatment with proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), or IL-6. In TNF-alpha deficient macrophages, the expression of NOD molecules was minimal at 12 hr, and the second rise in NOD mRNA seen in lipopolysaccharide-treated RAW264.7 cells was inhibited with anti-TNF-alpha, but not with anti-IL-1beta or anti-IL-6 antibody. These observations suggest that immediate response of NODs to endotoxins could result from NF-kappaB activation via TLR signaling, whereas the second rise in NOD mRNAs might have resulted from TNF-alpha production possibly through NF-kappaB, TLR, and/or NOD signalings.

Adaptor Proteins, Signal Transducing↗

Identification of Card15/Nod2 mRNA in intestinal tissue of experimentally induced colitis in rats.

Card15/Nod2 has been suggested to be an intracellular pathogen-associated molecular pattern (PAMPs) recognition molecule, which contains a leucine-rich repeat region similar to the Toll-like receptors (TLRs). Card15/Nod2 gene variants play an important role in the susceptibility to Crohn's disease. In this study, we examined the kinetics of Card15/Nod2 expression in intestinal tissue during inflammation in the 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-treated rat experimental colitis model. At 2 and 4 days after TNBS administration, the mononuclear cells remarkably infiltrated the mucosal layer and tunica muscularis, which was followed by a gradual decrease to resting levels at 14 days after TNBS administration. Card15/Nod2 mRNA expression increased and peaked at 4 days after the TNBS administration, followed by a gradual decrease in accordance with the amelioration of the inflammatory response. Expressions of Tlr2, Tlr4 and Myd88 were also upregulated in the inflamed colonic region, and in an in situ hybridization study, a positive signal for Card15/Nod2 was observed in the crypt of the epithelial cell layer and in the infiltrated cells of the submucosal and myenteric regions. These results suggest that in addition to the TLR recognition systems, Card15/Nod2 may contribute to the inflammatory process not only in the epithelial and submucosal layers but also in the tunica muscularis.

Animals↗

Assessment of two 3D MDCT colonography protocols for observation of colorectal polyps.

OBJECTIVE: The objective of our study was to assess the value of two-way interpretation (i.e., from rectum to cecum and vice versa) compared with one-way interpretation (i.e., from rectum to cecum only) in terms of polyp detection and interpretation time on MDCT colonography. MATERIALS AND METHODS: Fifty consecutive patients underwent both CT colonography and conventional colonoscopy. Three radiologists independently analyzed the CT colonographic examinations of each patient using a primary 3D method. All examinations were analyzed using two techniques: navigation from rectum to cecum only (one-way) and navigation from rectum to cecum and vice versa (two-way). Sensitivity and positive predictive value were calculated on both a per-polyp basis and a per-patient basis. Alternative free-response receiver operating characteristic (ROC) curve analysis was estimated, and image interpretation time was documented. RESULTS: One hundred fifty-five polyps were depicted in 45 patients by colonoscopy. The mean sensitivity of CT colonography for polyp detection with two-way (88.4%) was significantly superior to that with one-way (78.1%) (p < 0.01). The mean positive predictive value of each observer with one-way was 66.7%, whereas that with two-way was 65.8%. The mean area under the alternative free-response ROC curve (A(z) value) with two-way (0.827) was higher than that with one-way (0.816), but there was not a statistically significant difference. The average interpretation time of each observer with two-way (39 min) was statistically significantly longer than that with one-way (25 min) (p < 0.01). CONCLUSION: When using a primary 3D interpretation technique at CT colonography, complete 3D navigation from rectum to cecum and from cecum to rectum is mandatory to maximize polyp detection. The image interpretation time for two-way interpretation is statistically significantly longer than that with one-way interpretation.

Adult↗

Assessment of the severity of liver disease and fibrotic change: the usefulness of hepatic CT perfusion imaging.

This study assessed the utility of CT perfusion for quantitative assessment of liver function and fibrosis. Tissue blood flow (TBF), tissue blood volume (TBV), mean transit time (MTT) and hepatic arterial fraction (HAF) were measured with CT perfusion using the deconvolution algorithm in 38 patients with chronic liver diseases and 10 patients without liver disease. Using Child-Pugh classification, 21 patients were classified as Child A, 10 as Child B, and 7 as Child C. In 20 patients, the degree of fibrosis was quantitated in surgically-resected specimens and compared with the perfusion parameters. The mean TBF, TBV, MTT and HAF of patients with-out liver disease were 103.9+/-18 ml/min/100 g, 12.5+/-2.0 ml/100 g, 11.1+/-1.6 sec and 18.4+/-5.6%, respectively (+/-SD). The mean TBF of patients with Child A, B and C were 95.1+/-24, 86.7+/-29 and 75.5+/-6.5 ml/min/100 g, respectively. TBF tended to decrease with the severity of chronic liver disease. The mean HAF of patients with Child A, B and C were 18.6+/-8.3, 29.8+/-11.2 and 40.2+/-11.1%, respectively. HAF of patients without liver disease was significantly different from those of Child B and C (p<0.05, each). However, there were no significant differences in TBV and MTT between each groups. HAF correlated significantly with the degree of fibrosis (R2=0.588, p<0.05). Our results showed that parameters of CT perfusion correlated significantly with the severity of liver fibrosis and cirrhosis. Quantitative measurement of hepatic tissue blood flow by CT perfusion is useful for evaluation of the severity of disease and fibrotic change.

Adult↗

Differences in the gestational pattern of mRNA expression of the Rnd family in rat and human myometria.

Uterine myometrial contractility remains a poorly characterized area of research in reproductive physiology. Rnd1, a novel member of the GTP-binding Rho protein family, inhibits Ca(2+)-sensitization by specifically interfering with a RhoA/Rho-activated kinases-dependent mechanism in smooth muscle. In addition to Rnd1, there are two other members, Rnd2 and Rnd3, in the Rnd family of Rho proteins. In the present comparative study of myometrial contractility in rats and humans, we found that all three Rnd mRNAs were expressed in nonpregnant rat myometrium and in nonpregnant human myometrial tissues. Although all three mRNA levels increased significantly after gestation in rat myometria, only Rnd1 expression was significantly greater after gestation in human samples. In the ovariectomized rat, administration of estrogen and/or progesterone increased the expression of all Rnd mRNAs. These results suggest that universal Rnd family up-regulation during pregnancy in rats may have an important role for negative-feedback control of uterine contraction during gestation by inhibiting RhoA-mediated increase in Ca(2+) sensitivity of contractile elements. Such increases in Rnd levels may be due to augmented levels of reproductive steroids in rats. Our data also point to gestational differences between rats and humans in Rnd isoform patterns.

Adult↗

T staging of gastric cancer: role of multi-detector row CT.

PURPOSE: To evaluate retrospectively the accuracy of multi-detector row computed tomography (CT) in the assessment of serosal invasion in patients with gastric cancer. MATERIALS AND METHODS: The Ethics Committee does not require approval or informed consent for retrospective studies. Forty-one consecutive patients (24 men, 17 women; mean age, 68 years) with gastric cancer were included in this study. All patients were given 600 mL of tap water to drink and were positioned prone or supine on the scanning table. The detector row configuration included four detector rows, a section thickness of 1.25 mm, a pitch of 6, and a reconstruction interval of 0.63 mm. Transverse and multiplanar reconstruction images were simultaneously evaluated by two independent observers to assess the depth of tumor invasion in the gastric wall (ie, T stage). T staging at multi-detector row CT was compared with T staging at histologic evaluation (reference standard), which was performed by means of surgical or histologic examination of the resected specimen. We also calculated the sensitivity, specificity, and accuracy of multi-detector row CT for each observer in the assessment of serosal invasion. RESULTS: Analysis of interobserver agreement showed substantial or almost perfect agreement (nonweighted kappa value of 0.78 and weighted kappa value of 0.85). Correct assessment of gastric wall invasion was 80% and 85% for observers 1 and 2, respectively. The sensitivity, specificity, and accuracy of multi-detector row CT in the assessment of serosal invasion were 90%, 95%, and 93%, respectively, for observer 1 and 80%, 97%, and 93%, respectively, for observer 2. Overstaging occurred in six patients, and understaging occurred in five patients. All understaged tumors were scirrhous subtype gastric cancer. CONCLUSION: Multi-detector row CT scanning of patients with gastric cancer gave 93% accuracy in the assessment of serosal invasion in patients with gastric cancer.

Adult↗

Statin protects endothelial nitric oxide synthase activity in hypoxia-induced pulmonary hypertension.

OBJECTIVE: We investigated the effects of fluvastatin on hypoxia-induced (1 to 3 weeks, 10% O2) pulmonary hypertension with focus on endothelial nitric oxide synthase (eNOS) activity. METHODS AND RESULTS: Oral fluvastatin treatment (1 mg/kg daily) prevented the causing and progression of pulmonary hypertension as determined by the right ventricular pressure, right ventricular hypertrophy, and muscularization of pulmonary artery. We also revealed that fluvastatin treatments prevented the hypoxia-induced decrease in cGMP production in the rat lung and restored the endothelium-dependent relaxation in the pulmonary artery. We revealed that this beneficial effect was not dependent on the increase in eNOS mRNA or protein expression, but was dependent on the inhibition of the eNOS-tight coupling with caveolin-1, the eNOS dissociation from heat shock protein 90, and the decrease in eNOS Ser1177-phosphorylation induced by hypoxia. Furthermore, in a whole-mount immunostaining the hypoxia-induced eNOS protein condensation with caveolin-1 of pulmonary endothelial cells was restored by the fluvastatin-treatment. CONCLUSIONS: These results suggest that the fluvastatin exerts beneficial effects on chronic hypoxia-induced pulmonary hypertension by protecting against the eNOS activity at the post-transcriptional level.

Animals↗

Vascular endothelium has a local anti-adenovirus vector system and glucocorticoid optimizes its gene transduction.

OBJECTIVE: Although adenovirus is a powerful tool for vascular research and therapy, endothelial impairment after infection has been reported. We investigated the mechanisms of this impairment and the effect of dexamethasone (DEX) on gene transfer into the vascular endothelial cells. METHODS AND RESULTS: Beta-galactosidase gene encoding adenovirus vector (beta-gal-Ad) (7.5 x 10(8) plaque-forming units/mL) transduced beta-gal into the rabbit organ-cultured pulmonary endothelium, followed by an apoptosis and an impairment of endothelium-dependent relaxation (EDR). Endothelial cell infected by beta-gal-Ad expressed proinflammatory genes mRNAs and suppressed endothelial nitric oxide synthase (eNOS) mRNA. Treatment with DEX dramatically increased beta-gal protein expression in the endothelium, attenuated beta-gal-Ad-induced apoptosis, and prevented the impairment of EDR. DEX also suppressed the mRNAs expressions of proinflammatory genes and recovered eNOS mRNA expression in organ-cultured vascular endothelium. In addition, we confirmed the DEX's beneficial effects in an endothelial cell line (in vitro) and rat femoral artery (in vivo) experiments. CONCLUSIONS: These results suggest that adenovirus vector induces host-immune responses and apoptosis in vascular endothelial cells. DEX is found to be a useful and potent tool to prevent the Ad-induced impairments of the endothelium and to optimize gene expression efficiency by adenovirus vector at the protein translation level in both in vitro and in vivo experiments.

Adenoviridae↗

Dexamethasone prevents impairment of endothelium-dependent relaxation in arteries cultured with fetal bovine serum.

In the present study, we assessed the effects of dexamethasone on fetal bovine serum-induced dysfunction of mesenteric endothelial cells using an organ culture procedure. In rabbit mesenteric arteries cultured in the presence of 10% fetal bovine serum for 7 days, the endothelium-dependent, nitric oxide (NO)-mediated relaxations caused by substance P and ionomycin were decreased as compared to those in non-treated arteries. Dexamethasone (3 microM) inhibited the proliferative stimuli-induced endothelial dysfunction without affecting the contractility or NO susceptibility of smooth muscle cells. Cross-sectioned hematoxylin-eosin staining and whole-mount CD31 staining indicated that chronic proliferative stimulation induced detachment of endothelial cells from the tunica intima in some regions, and also caused thickening of the arterial wall and shortening of the internal diameter. Endothelial NO synthesis (eNOS) mRNA expression was also decreased by the treatment with fetal bovine serum. The dexamethasone treatment did not inhibit the smooth muscle hypertrophy, but it inhibited the peeling of endothelial cells and recovered the eNOS mRNA expression. These results suggest that DEX ameliorate the impairments of arterial relaxation induced by proliferative stimuli and that these beneficial effects may be mediated by maintaining the adhesion of endothelial cells to the vascular wall and/or by recovering eNOS mRNA expression.

Animals↗

Microtubule disruption suppresses allergic response through the inhibition of calcium influx in the mast cell degranulation pathway.

Mast cells are secretory cells that release their granules, which contain inflammatory mediators. Some recent data suggested that cytoskeletons play a role in this process. However, the role of microtubules in Ca2+ signaling has not yet been well defined. In this study, we demonstrate that the microtubule cytoskeleton is important to maintain Ca2+ influx in the degranulation pathway of mast cells, using the microtubule depolymerizers nocodazole and colchicine. The microtubule depolymerizers inhibited Ag-induced degranulation in RBL-2H3 cells and bone marrow-derived mast cells. When the cells were stimulated with Ag in the presence of the microtubule depolymerizers, the Ca2+ influx was decreased without affecting Ca2+ release from the endoplasmic reticulum (ER). Capacitative Ca2+ entry, which was induced by inhibitors of Ca(2+)-ATPase in the ER membrane, thapsigargin and cyclopiazonic acid, was also decreased by nocodazole. Fluorescent probe analysis demonstrated that nocodazole disrupted microtubule formation and changed the cytoplasmic distribution of the ER. The microtubule depolymerizers attenuated the passive cutaneous anaphylaxis reaction in back skin of Sprague Dawley rats. These results suggest that the microtubule cytoskeleton in mast cells is important to maintain Ag-induced capacitative Ca2+ entry, which is responsible for degranulation and the allergic response.

Animals↗