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1.
J Hosp Infect ; 138: 52-59, 2023 Aug.
Article En | MEDLINE | ID: mdl-37277015

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has influenced hospital infection control practices. AIM: To evaluate the impact of the COVID-19 pandemic on healthcare-associated infections (HAIs) in intensive care units (ICUs). METHODS: A retrospective analysis using data from the Korean National Healthcare-Associated Infections Surveillance System was conducted. Comparisons between incidence rates and micro-organism distributions of bloodstream infection (BSI), central line-associated bloodstream infections (CLABSI), catheter-associated urinary tract infection (CAUTI), and ventilator-associated pneumonia (VAP) before and during the COVID-19 pandemic were performed according to hospital size. FINDINGS: The incidence rate of BSI significantly decreased during the COVID-19 pandemic compared to the pre-COVID-19 period (1.38 vs 1.23 per 10,000 patient-days, relative change -11.5%; P < 0.001). The incidence rate of VAP (1.03 vs 0.81 per 1000 device-days, relative change -21.4%; P < 0.001) significantly decreased during the COVID-19 pandemic compared to the pre-COVID-19 period, whereas rates of CLABSI (2.30 vs 2.23 per 1000 device-days; P = 0.19) and CAUTI (1.26 vs 1.26 per 1000 device-days; P = 0.99) were similar between the two periods. The rates of BSI and CLABSI significantly increased during the COVID-19 pandemic compared to the pre-COVID-19 period in large-sized hospitals, whereas these rates significantly decreased in small-to-medium-sized hospitals. The rates of CAUTI and VAP significantly decreased in small-sized hospitals. There were no significant changing trends in the rates of multidrug-resistant pathogens isolated from patients with HAI between the two periods. CONCLUSION: The incidence rates of BSI and VAP in ICUs decreased during the COVID-19 pandemic compared to the pre-COVID-19 period. This decrease was mainly seen in small-to-medium-sized hospitals.


COVID-19 , Catheter-Related Infections , Cross Infection , Pneumonia, Ventilator-Associated , Sepsis , Urinary Tract Infections , Humans , Catheter-Related Infections/epidemiology , COVID-19/epidemiology , Cross Infection/epidemiology , Intensive Care Units , Pandemics , Pneumonia, Ventilator-Associated/epidemiology , Republic of Korea/epidemiology , Retrospective Studies , Sepsis/epidemiology , Urinary Tract Infections/epidemiology
2.
J Dent Res ; 102(7): 825-834, 2023 07.
Article En | MEDLINE | ID: mdl-37246809

The enamel knot (EK), located at the center of cap stage tooth germs, is a transitory cluster of nondividing epithelial cells. The EK acts as a signaling center that provides positional information for tooth morphogenesis and regulates the growth of tooth cusps. To identify species-specific cuspal patterns, this study analyzed the cellular mechanisms in the EK that were related to bone morphogenetic protein (Bmp), which plays a crucial role in cell proliferation and apoptosis. To understand the cellular mechanisms in the EK, the differences between 2 species showing different cuspal patterning, mouse (pointy bunodont cusp) and gerbil (flat lophodont cusp), were analyzed with quantitative reverse transcriptase polymerase chain reaction and immunofluorescent staining. Based on these, we performed protein-soaked bead implantation on tooth germs of the 2 different EK regions and compared the cellular behavior in the EKs of the 2 species. Many genes related with cell cycle, cell apoptosis, and cell proliferation were involved in BMP signaling in the EK during tooth development. A comparison of the cell proliferation and apoptosis associated with Bmp revealed distinctive patterns of the cellular mechanisms. Our findings indicate that the cellular mechanisms, such as cell proliferation and apoptosis, in the EK are related to Bmp4 and play an important role in tooth morphogenesis.


Tooth , Animals , Mice , Dental Enamel/metabolism , Odontogenesis/genetics , Tooth Germ , Bone Morphogenetic Proteins/metabolism , Cell Proliferation , Apoptosis , Bone Morphogenetic Protein 4/metabolism
3.
Phys Rev Lett ; 130(11): 111801, 2023 Mar 17.
Article En | MEDLINE | ID: mdl-37001070

We present the first search for the pair production of dark particles X via K_{L}^{0}→XX with X decaying into two photons using the data collected by the KOTO experiment. No signal was observed in the mass range of 40-110 MeV/c^{2} and 210-240 MeV/c^{2}. This sets upper limits on the branching fractions as B(K_{L}^{0}→XX)<(1-4)×10^{-7} and B(K_{L}^{0}→XX)<(1-2)×10^{-6} at the 90% confidence level for the two mass regions, respectively.

4.
Poult Sci ; 101(4): 101705, 2022 Apr.
Article En | MEDLINE | ID: mdl-35183990

Two consecutive 35 d experiments were conducted to investigate the effects of a multistrain DFM fed continuously to broiler chickens exposed to HS from 28 to 35 d on broiler performance, body composition, ileal digestibility, and intestinal permeability using serum Fluorescein Isothiocyanate Dextran (FITC-d) concentration. The treatments were arranged as a 2 × 2 factorial with temperature: Elevated (HS: 33 ± 2°C for 6 h and 27.7°C for the remaining 18 h from 28 to 35 days of age) and Thermoneutral (TN: 22 to 24°C over the entire 24-h day from 28 to 35 days of age) and diet: corn-soybean meal based with and without DFM (3-strain Bacillus; Enviva PRO) fed over the entire 35-d period as the two factors. Experimental diets were formulated to meet all nutrient recommendations based on breed standards using a starter (0-10 d), grower (10-21 d), and finisher (21-35 d) period. For each of the 2 experiments, 648 Ross 708 broiler chicks were allotted among the treatments with 9 replicate pens of 18 broilers. Data were analyzed as a 2 × 2 factorial within each experiment in JMP 14. In both experiments, cloacal temperatures were increased (P ≤ 0.05) in the broilers subjected to the HS treatment at both 28 d (acute) and 35 d (chronic). Supplementing birds with DFM reduced cloacal temperatures in the Experiment 1 at 28 d, but not at the other time periods. The HS treatment reduced body weight gain and lean tissue accretion from 0 to 35 d in both experiments (P ≤ 0.05). In Experiment 2, when the litter was reused BWG was increased by 36 g/bird with supplementation of DFM (P ≤ 0.05). Ileal digestibility at 28 d (2 h post HS) was improved with DFM supplementation in both experiments (P ≤ 0.05). Serum FITC-d increased with HS at both 28 and 35 d. Serum FITC-d was generally decreased with DFM at 28 d but the response was inconsistent at 35 d. Overall, the results suggest that HS reduced broiler performance and DFM treatment improved intestinal permeability and nutrient digestibility responses to HS in both experiments but did not improve performance until built up litter was used in Experiment 2.


Chickens , Heat Stress Disorders , Animal Feed/analysis , Animal Nutritional Physiological Phenomena , Animals , Chickens/physiology , Diet/veterinary , Dietary Supplements/analysis , Fluorescein-5-isothiocyanate , Heat Stress Disorders/veterinary , Heat-Shock Response , Plant Breeding
5.
6.
Phys Rev Lett ; 126(12): 121801, 2021 Mar 26.
Article En | MEDLINE | ID: mdl-33834796

The rare decay K_{L}→π^{0}νν[over ¯] was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of (7.20±0.05_{stat}±0.66_{syst})×10^{-10}, three candidate events were observed in the signal region. After unveiling them, contaminations from K^{±} and scattered K_{L} decays were studied, and the total number of background events was estimated to be 1.22±0.26. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of 4.9×10^{-9} on the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level.

7.
Poult Sci ; 100(2): 755-759, 2021 Feb.
Article En | MEDLINE | ID: mdl-33518129

Effects of the in ovo injection of organic microminerals (OM) (zinc, manganese, and copper) and posthatch holding time (HT) on the daily body temperature (bt) of broilers during grow out were determined. The hatching eggs from a Ross 708 breeder flock at 32 wk of age were incubated under standard commercial conditions. At 17 d of incubation, eggs were randomly allocated to 3 in ovo OM injection treatment (TRT) groups, and at 21 d of incubation, male hatchlings were randomly allocated to 2 posthatch HT treatment groups. Eggs were either not injected or were in ovo injected with diluent only or diluent containing the OM mixture. A 0-hour HT group had immediate access to water and feed, and a 24-hour HT (24HT) group contained birds that were kept in transport baskets in their pens without access to feed and water for 24 h before being released. Fifteen male birds were placed in each of 36 litter floor pens in a temperature-controlled facility. Approximately 2 birds in each of 6 replicate pens belonging to each TRT-HT combination had temperature transponders inserted subcutaneous in the mid-dorsal region of the neck. All birds were brooded under standard commercial conditions and had ad libitum access to feed and water after their respective HT. The bt of the same birds were determined daily at the same time each day beginning at hatch and ending on 39 d of posthatch age (AGE). There were no significant main or interactive effects involving TRT or HT for bt. However, there was a significant (P ≤ 0.0001) main effect because of AGE. A general increase in bt occurred during the 39 d grow out period. At hatch, bt was 40.54 ± 0.056°C and at AGE 39 was 41.46 ± 0.055°C. Under standard brooding conditions, a general increase in bt occurred in the Ross 708 broilers. However, these birds did not exhibit a significant bt response to TRT or a 24HT before placement.


Body Temperature , Chickens , Copper/administration & dosage , Manganese/administration & dosage , Zinc/administration & dosage , Animals , Chickens/growth & development , Male , Random Allocation , Temperature , Time Factors , Zygote/drug effects
9.
Skin Health Dis ; 1(3): e45, 2021 Sep.
Article En | MEDLINE | ID: mdl-35663135

Background: Patients with cutaneous T-cell lymphoma (CTCL) often have indolent but symptomatic disease. Objective: Assessment of the health-related quality of life (HRQoL) of patients with CTCL. Methods: Cross-sectional survey study. HRQoL was measured by Skindex-16 and FACT-G. Results: A total of 372 responses were received; 80 incomplete/ineligible responses were excluded. A majority of respondents identified as white (87%; 250/288) and female (67%; 193/286) with a mean age of 57 ± 14 years. Most patients had early-stage (IA-IIA) (74%; 162/203) mycosis fungoides (87%; 241/279). There were 33 (12%; 33/279) patients with Sézary syndrome. Mean itch score (visual analogue scale; VAS) was 3.2 ± 2.8, overall; 2.7 ± 2.6 for early, and 4.2 ± 2.9 for advanced disease (p = 0.008). Thirty-eight percent (108/284) and 24% (69/284) reported head/neck and groin/genital involvement, respectively.Overall HRQoL was 46 ± 27 (Skindex-16) and 71 ± 19 (FACT-G), with worse HRQoL for patients with advanced versus early disease (Skindex-16: 67 vs. 40; p=<0.001, FACT-G: 62 vs. 76; p = 0.001). Predictors of worse HRQoL included head/neck, hand/foot or groin/genital involvement, younger age and spending >15 min daily treating CTCL. Limitations: Include anonymous survey methodology, underrepresentation of certain CTCL subtypes and non-white respondents. Conclusions: Patients with CTCL, particularly those with advanced disease or involvement of the head/neck, acral or groin/genital sites, experience significant impact on HRQoL.

10.
BMJ Mil Health ; 167(2): 80-83, 2021 Apr.
Article En | MEDLINE | ID: mdl-32276967

INTRODUCTION: Humeral shaft fractures can lead to radial nerve injury and may require surgery and rehabilitation. We determined the causative events of humeral fracture, including arm wrestling, in young Korean soldiers and examined whether humeral fracture is related to demographic characteristics and the presence of radial nerve palsy. METHODS: We reviewed 7.5 years (July 2012 to June 2019) of medical records covering patients who had experienced a humeral shaft fracture after entering military service and had received surgery for open reduction and internal fixation. Data were obtained on basic demographics, initial event provoking the fracture, presence of radial nerve palsy, initial and follow-up severity of the weakness, and any discharge from military service because of prolonged radial nerve palsy. RESULTS: Of 123 cases, arm wrestling was the leading cause (52.8%). A high energy injury, such as falling from a height (11.4%), and sports related slips (10.6%) were other causes. All humeral shaft fractures caused by forceful contraction were spiral, while 40% of the fractures caused by external force related events were of a transverse type. The percentage of left-sided fractures was significantly higher for fractures arising from an external force than in those caused by forceful contraction related events. Radial nerve palsy was found in 34 patients (27.6%), and 16 were discharged from the military because of prolonged radial nerve palsy 6 months after the fracture. The causative events and other factors did not affect the presence of radial nerve palsy. CONCLUSION: Arm wrestling was the leading cause of humeral fracture in young Korean soldiers but the chance of developing comorbid radial nerve palsy did not differ from that of other causes. These epidemiologic findings in this young active group may help in understanding the causes of humeral shaft fracture in soldiers and in the wider young population.


Humerus/injuries , Radial Neuropathy/etiology , Wrestling/injuries , Accidental Falls/statistics & numerical data , Humans , Humeral Fractures/complications , Humeral Fractures/epidemiology , Humerus/physiopathology , Male , Military Personnel/statistics & numerical data , Radial Neuropathy/epidemiology , Recovery of Function , Republic of Korea/epidemiology , Young Adult
11.
Poult Sci ; 99(9): 4373-4383, 2020 Sep.
Article En | MEDLINE | ID: mdl-32867981

Effects of dietary Original XPC (XPC) on 17 selected blood variables in commercial layer pullets challenged with the virulent, low-passage R strain of Mycoplasma gallisepticum (RlowMG) were investigated. Hy-Line W-36 pullets sourced from M. gallisepticum-clean layer breeders were fed a basal diet with XPC (1.25 kg/metric ton) or without from hatch until 12 wk of age (woa). At 8 and 10 woa, half of the birds in each dietary treatment were challenged with RlowMG. Blood samples were taken immediately before the initial RlowMG challenge at 8 woa and again at 12 woa (4 wk after challenge). At 8 woa, blood pH was lower and glucose concentration was higher in the preassigned challenge treatment groups. At 12 woa, the concentration of oxygen dissolved in the blood was significantly lower in the RlowMG-challenged group than the unchallenged group of birds regardless of dietary treatment. The RlowMG challenge significantly increased blood carbon dioxide partial pressure, calcium, sodium, anion gap, osmolality, glucose, and corticosterone levels but significantly decreased blood oxygen partial pressure, oxyhemoglobin concentration, concentration of oxygen dissolved in the blood, chloride, and pH levels. Because blood pH and glucose concentration at 8 woa were examined before challenge, their baseline values were biased with respect to challenge treatment before treatment was applied. However, the lack of a significant main effect due to diet at 8 woa for blood pH and glucose concentration, along with the other 15 blood variables, indicate that the baseline data with respect to dietary treatment were unbiased, allowing for real dietary effects to be accurately assessed. In conclusion, layer pullets challenged with RlowMG undergo a stress response associated with changes in various physiological blood variables, and a decrease in pH and increase in carbon dioxide partial pressure, in association with a lack of change in bicarbonate, indicates that the stress response caused by the RlowMG challenge was associated with respiratory acidosis. Nevertheless, feeding XPC did not influence the effects of challenge treatment on these postchallenge physiological blood values.


Chickens , Dietary Supplements , Fermented Foods , Mycoplasma Infections , Mycoplasma gallisepticum , Poultry Diseases , Animals , Diet/veterinary , Female , Mycoplasma Infections/blood , Mycoplasma Infections/prevention & control , Mycoplasma Infections/veterinary , Poultry Diseases/blood , Poultry Diseases/prevention & control
12.
Poult Sci ; 99(6): 3030-3037, 2020 Jun.
Article En | MEDLINE | ID: mdl-32475439

Effects of dietary Original XPC (XPC) in commercial layer pullets challenged with the virulent, low passage R strain of Mycoplasma gallisepticum (Rlow MG) were investigated. Hy-Line W-36 pullets sourced from MG-clean breeders were fed a basal diet with or without (CON) XPC (1.25 kg/metric ton) from hatch until 12 wk of age (woa). At 8 and 10 woa, half of the birds in each dietary treatment were challenged with Rlow MG. Body weight was recorded at 3, 8, and 12 woa, and ovary, ceca, and bursa weights were recorded at 3 and 12 woa. Blood samples were taken immediately before the initial Rlow MG challenge at 8 woa and again at 12 woa to test for IgM and IgG antibody production against MG. All birds were evaluated for MG lesion scores at 12 woa. Regardless of challenge, inclusion of XPC in the diet did not significantly alter BW at 3 or 8 woa or relative organ weights at 3 or 12 woa. However, at 12 woa, BW of XPC-fed birds, regardless of challenge was significantly (P = 0.0038) heavier than CON by 25.7 g. All birds tested negative for MG antibodies before the 8 woa challenge. Respective percentage serum plate agglutination and ELISA positive birds at 12 woa were 0 and 0% (CON, nonchallenged), 1.4 and 0% (XPC, nonchallenged), 100 and 47.2% (CON, challenged), and 100 and 50.0% (XPC, challenged). Diet did not significantly affect ELISA titers, but they were significantly (P < 0.0001) increased due to challenge. Furthermore, lesion scores were significantly higher for Rlow MG-challenged birds (P = 0.0012), and dietary treatment with XPC in challenged birds numerically reduced MG lesion scores from 0.278 to 0.194. In conclusion, although dietary XPC did not significantly alter the humoral immune response, antibody titer levels, or severity of MG lesions in layer pullets that were or were not challenged with Rlow MG, it led to an increase in their rate of growth through 12 woa.


Chickens/growth & development , Chickens/immunology , Immunity, Humoral/drug effects , Mycoplasma gallisepticum/physiology , Poultry Diseases/immunology , Prebiotics/administration & dosage , Animal Feed/analysis , Animals , Diet/veterinary , Female , Mycoplasma Infections/immunology , Mycoplasma Infections/veterinary
14.
Phys Rev Lett ; 122(2): 021802, 2019 Jan 18.
Article En | MEDLINE | ID: mdl-30720307

A search for the rare decay K_{L}→π^{0}νν[over ¯] was performed. With the data collected in 2015, corresponding to 2.2×10^{19} protons on target, a single event sensitivity of (1.30±0.01_{stat}±0.14_{syst})×10^{-9} was achieved and no candidate events were observed. We set an upper limit of 3.0×10^{-9} for the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for K_{L}→π^{0}X^{0} was also set as 2.4×10^{-9} at the 90% C.L., where X^{0} is an invisible boson with a mass of 135 MeV/c^{2}.

16.
QJM ; 111(11): 769-778, 2018 Nov 01.
Article En | MEDLINE | ID: mdl-30016493

BACKGROUND: Tumor-associated macrophages (TAMs) are important determinants of intratumoral immune evasion, neoangiogenesis, extracellular matrix remodeling and dysregulated tumor cell proliferation. Our prior studies revealed that macrophage-derived, but not tumor cell-derived, macrophage migration inhibitory factor (MIF), is an important determinant of TAM alternative activation and M2 polarization. AIM: Because MIF is historically thought to initiate signaling via a receptor-dependent, outside-in mode of action, we wished to investigate the specific contributions of tumor-derived vs. macrophage-derived MIF to M2 marker expression during macrophage polarization. DESIGN: Murine oral squamous cell-carcinoma cells (SCCVII) were co-cultured with either the RAW 264.7 mouse macrophage cell line or mouse primary bone marrow-derived macrophages in the context of MIF genetic loss/inhibition individually or in combination each cell type. METHODS: Twelve well Transwell plates were used to co-culture SCCVII cells and RAW 264.7, MIF+/+ or MIF-/- macrophages treated with/without the small molecule MIF inhibitor, 4-iodo-6-phenylpyrimidine and incubated in the presence or absence of interleukin (IL-4) for 48 h. Macrophages were analyzed by quantitative real-time polymerase chain reaction and/or immunoblotting for relative macrophage polarization marker expression. RESULTS: IL-4 treatment synergizes with SCCVII co-culture in inducing the expression of macrophage M2 markers and loss or inhibition of macrophage-derived MIF significantly reduces both IL-4 alone and IL-4/SCCVII co-culture-induced macrophage M2 marker expression. CONCLUSION: These studies identify an important and dominant requirement for macrophage MIF in maximal Th2-cytokine and oral squamous carcinoma cell-induced macrophage polarization and M2 marker expression.


Carcinoma, Squamous Cell/metabolism , Intramolecular Oxidoreductases/metabolism , Macrophage Migration-Inhibitory Factors/metabolism , Macrophages/cytology , Animals , Carcinoma, Squamous Cell/immunology , Cell Line, Tumor , Cell Proliferation , Coculture Techniques , Interleukin-4/pharmacology , Intramolecular Oxidoreductases/antagonists & inhibitors , Macrophage Migration-Inhibitory Factors/antagonists & inhibitors , Macrophages/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Neovascularization, Pathologic/metabolism , Pyrimidines/pharmacology , RAW 264.7 Cells
17.
Meat Sci ; 145: 195-201, 2018 Nov.
Article En | MEDLINE | ID: mdl-29982073

The main objective of this study was to compare the eating quality among the groups categorized by the Korean beef quality grade and texture feature of exposed muscle surface assessed by extent of dented areas and firmness. Additionally, this study also investigated the effects of fiber and bundle characteristics on texture feature to establish the cause of differences in muscle surface texture. Significant differences were observed in the sensory quality characteristics among the quality grades mainly determined by marbling score (P < 0.05). However, the coarse texture group with a dented surface required a higher initial force to penetrate meat (P < 0.001), was more difficult to break meat into fragments (P < 0.001), and had a higher amount of perceptible residue in the mouth (P < 0.01) compared to the fine texture group. These differences in the surface texture features between the fine and coarse groups could be explained by bundle area and fiber number per each bundle.


Consumer Behavior , Muscle Fibers, Skeletal , Muscle, Skeletal , Red Meat/analysis , Surface Properties , Adult , Animals , Cattle , Female , Hardness , Humans , Male , Species Specificity , Stress, Mechanical , Young Adult
18.
Transplant Proc ; 50(5): 1365-1371, 2018 Jun.
Article En | MEDLINE | ID: mdl-29880358

BACKGROUND: Sympathetic blockade associated with epidural analgesia was reported to be a risk factor for acute kidney injury (AKI) following liver resection. The purpose of this study was to compare the incidence of AKI after living-donor hepatectomies according to the type of patient-controlled analgesia (PCA). METHODS: A total of 316 patients after living-donor hepatectomy were retrospectively analyzed; 148 patients in the epidural PCA group and 168 patients in the intravenous (IV) PCA group were evaluated. AKI was defined as an increase in serum creatinine ≥0.3 mg/dL, ie, 1.5-fold from the baseline, or a reduction in the urine output in the first 48 hours after surgery, based on the Acute Kidney Injury Network criteria. Logistic regression analysis was performed to identify the independent risk factors for AKI after living-donor hepatectomy. RESULTS: Baseline characteristics were similar between the 2 groups except the age. Volumes of fluids and colloids administered intraoperatively were greater in the epidural PCA group (P < .001 and P = .006, respectively). The incidence of AKI did not show significant differences between the 2 groups (8.1% vs 7.1%; P = .747). In multivariate analysis, preoperative serum alanine transaminase level ≥50 U/L was identified as a risk factor for postoperative AKI. However, epidural PCA failed to be a risk factor for postoperative AKI. CONCLUSIONS: The type of PCA did not affect the incidence of postoperative AKI after living-donor hepatectomy. Despite significant differences in the postoperative hemodynamics, the incidence of AKI was similar between 2 groups.


Acute Kidney Injury/epidemiology , Acute Kidney Injury/etiology , Analgesia, Patient-Controlled/adverse effects , Analgesia, Patient-Controlled/methods , Hepatectomy/adverse effects , Pain, Postoperative/drug therapy , Adult , Aged , Analgesia, Epidural/methods , Analgesics, Opioid/administration & dosage , Analgesics, Opioid/adverse effects , Female , Humans , Incidence , Infusions, Intravenous , Living Donors , Male , Middle Aged , Retrospective Studies , Risk Factors , Tissue and Organ Harvesting/adverse effects , Tissue and Organ Harvesting/methods
19.
J Dent Res ; 97(7): 828-834, 2018 07.
Article En | MEDLINE | ID: mdl-29489426

Species-specific cusp patterns result from the iterative formation of enamel knots, the epithelial signaling centers, at the future cusp positions. The expressions of fibroblast growth factors (FGFs), especially Fgf4, in the secondary enamel knots in the areas of the future cusp tips are generally used to manifest the appearance of species-specific tooth shapes. However, the mechanism underlying the predictive role of FGFs in species-specific cusp patterns remains obscure. Here, we demonstrated that gerbils, which have a lophodont pattern, exhibit a striped expression pattern of Fgf4, whereas mice, which have a bunodont pattern, have a spotted expression pattern, and these observations verify the predictive role of Fgf4 in species-specific cusp patterns. By manipulating FGFs' signaling in the inner dental epithelium of gerbils, we provide evidence for the intracellular participation of FGF signaling, specifically FGF4 and FGF20, in Rac1- and RhoA-regulated cellular geometry remolding during the determination of different cusp patterns. Our study presents a novel explanation of how different FGF expression patterns produce different cusp patterns and implies that a conserved intracellular FGF-GTPase signaling module might represent an underlying developmental basis for evolutionary changes in cusp patterns.


Dental Enamel/metabolism , Fibroblast Growth Factors/metabolism , Molar/anatomy & histology , Odontogenesis/physiology , Animals , Blotting, Western , Fluorescent Antibody Technique , Gerbillinae , In Situ Hybridization , Mice , Mice, Nude , Signal Transduction , Species Specificity
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