Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 20
Filter
1.
J Obstet Gynaecol ; 44(1): 2362968, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38885134

ABSTRACT

BACKGROUND: During the coronavirus disease (COVID-19) pandemic, caesarean section (CS) has been the preferred deliver method for pregnant women with COVID-19 in order to limit the use of hospital beds and prevent morbidity among healthcare workers. METHODS: To evaluate delivery methods used during the COVID-19 pandemic as well as the rates of adverse events and healthcare worker morbidity associated with caesarean deliveries. METHODS: We investigated maternal and neonatal backgrounds, delivery methods, indications and complication rates among pregnant women with COVID-19 from December 2020 to August 2022 in Mie Prefecture, Japan. The predominant mutation period was classified as the pre-Delta, Delta and Omicron epoch. RESULTS: Of the 1291 pregnant women with COVID-19, 59 delivered; 23 had a vaginal delivery and 36 underwent CS. Thirteen underwent CS with no medical indications other than mild COVID-19, all during the Omicron epoch. Neonatal complications occurred significantly more often in CS than in vaginal delivery. COVID-19 in healthcare workers was not attributable to the delivery process. CONCLUSION: The number of CS with no medical indications and neonatal complications related to CS increased during the COVID-19 pandemic. Although this study included centres that performed vaginal deliveries during COVID-19, there were no cases of COVID-19 in healthcare workers. It is possible that the number of CS and neonatal complications could have been reduced by establishing a system for vaginal delivery in pregnant women with recent-onset COVID-19, given that there were no cases of COVID-19 among the healthcare workers included in the study.


We evaluated the incidence of adverse events associated with caesarean section (CS) deliveries and the morbidity of health care workers, which increased during the coronavirus infection pandemic. Maternal and neonatal background, delivery methods, indications and complication rates of pregnant women with COVID-19 from December 2020 to August 2022 in Mie Prefecture were investigated by time of onset. Of the 1291 pregnant women with COVID-19, 59 delivered while affected; 23 underwent vaginal delivery and 36 CS. Of these, 13 who underwent CS in the omicron epoch had no medical indication other than mild COVID-19. Neonatal complications were significantly more common with CS than with vaginal delivery, and there was no occurrence of COVID-19 in healthcare workers. In this study, there were no cases of COVID-19 among health care workers; establishing a system to perform vaginal delivery for pregnant women with COVID-19 could have reduced the number of CS and neonatal complications.


Subject(s)
COVID-19 , Cesarean Section , Delivery, Obstetric , Pregnancy Complications, Infectious , SARS-CoV-2 , Humans , Female , Pregnancy , COVID-19/epidemiology , Japan/epidemiology , Adult , Pregnancy Complications, Infectious/epidemiology , Cesarean Section/statistics & numerical data , Delivery, Obstetric/statistics & numerical data , Delivery, Obstetric/methods , Infant, Newborn
2.
J UOEH ; 44(3): 313-319, 2022.
Article in Japanese | MEDLINE | ID: mdl-36089351

ABSTRACT

Before the outbreak of COVID-19, "Clinical Practice in Adult Nursing (Chronic Care)", a professional course to acquire basic nursing practice skills for the care of adult patients with chronic diseases, was conducted on site in the wards of internal medicine, outpatient departments, and the admissions support office for a total of three weeks. Due to the spread of the COVID-19 epidemic, however, clinical practice was carried out online from May 2020, and was resumed on site at our university hospital in October 2020. A restriction was placed on the length of time spent at the hospital for on-site training, referring to the training standards based on our university's new coronavirus response manual, and a training program was developed for hospital ward training, consisting mainly of shadowing practice performed without speaking or coming into contact with patients. In principle, two students were assigned to one patient: one in the morning and the other in the afternoon. In addition, for practicing the acquisition of patient information through conversation and the provision of nursing assistance, the perspectives used in the process of shadowing were clearly defined so that students could maintain active attitudes in clinical practice, and support was provided so that students could have the experience of engaging with patients, using nurses as mediators. In the results, the students evaluated the contents of the prepared assistance based on their own nursing plan in reference to the practice of the nurse as a mediator, and compared that with the assistance practiced by the nurse based on clinical judgment, which contributed to acquiring practical learning supported by the grounds for clinical judgment. However, the students could not experience the process of building supportive relationships and the implementation of nursing skills, which remained an issue.


Subject(s)
COVID-19 , Adult , Humans , Learning , Pandemics , Students
3.
Placenta ; 127: 73-76, 2022 09.
Article in English | MEDLINE | ID: mdl-35973367

ABSTRACT

Although SARS-CoV-2 can infect human placental tissue, vertical transmission is rare. Therefore, the placenta may function as a barrier to inhibit viral transmission to the foetus, though the mechanisms remain unclear. In this study, we confirmed the presence of the SARS-CoV-2 genome in human placental tissue by in situ hybridization with antisense probes targeting the spike protein; tissue staining was much lower when using sense probes for the spike protein. To the best of our knowledge, this is the first evidence directly indicating inefficient viral replication in the SARS-CoV-2-infected placenta. Additional studies are required to reveal the detailed mechanisms.


Subject(s)
COVID-19 , Pregnancy Complications, Infectious , Female , Humans , Infectious Disease Transmission, Vertical , Placenta/metabolism , Pregnancy , SARS-CoV-2 , Spike Glycoprotein, Coronavirus
4.
J Obstet Gynaecol Res ; 48(7): 1978-1982, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35605975

ABSTRACT

Although various perinatal outcomes in coronavirus disease 2019 (COVID-19) pregnancies have been reported, the fetal and neonatal consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remain unclear. Several reports of miscarriages and stillbirths have been recorded, but vertical transmission by SARS-CoV-2 is considered very rare, and the cause remains unknown. We report a case of a 22-year-old uncomplicated Japanese woman infected with SARS-CoV-2 during the second trimester, resulting in intrauterine fetal death due to placental insufficiency associated with COVID-19 placentitis. This report emphasizes the importance of longitudinal assessment of fetal well-being by fetal heart rate monitoring and early detection of maternal coagulation dysfunction representing SARS-CoV-2 inflammation to manage COVID-19 in pregnancy.


Subject(s)
Blood Coagulation Disorders , COVID-19 , Chorioamnionitis , Pregnancy Complications, Infectious , Adult , COVID-19/complications , Female , Fetal Death/etiology , Heart Rate, Fetal , Humans , Infant, Newborn , Infectious Disease Transmission, Vertical , Placenta , Pregnancy , Pregnancy Outcome , SARS-CoV-2 , Stillbirth , Young Adult
5.
Mol Cell Endocrinol ; 532: 111319, 2021 07 15.
Article in English | MEDLINE | ID: mdl-33989714

ABSTRACT

AIMS: Infants born to women with Type 2 Diabetes Mellitus (T2DM) are at risk of being born large for gestational age due to excess fetal fat accretion. Placental nutrient transport determines fetal nutrient availability, impacting fetal growth. The aims of the study were to evaluate the effect of T2DM on placental insulin signaling, placental nutrient transporters and neonatal adiposity. METHODS: Placentas were collected from BMI-matched normoglycemic controls (NGT, n = 9) and T2DM (n = 9) women. Syncytiotrophoblast microvillous (MVM) and basal (BM) plasma membranes were isolated. Expression of glucose (GLUT1, -4), fatty acid (FATP2, -4, -6, FAT/CD36), amino acid (SNAT1, -2, -4, LAT1, -2) transporters, insulin signaling, and System A transporter activity was determined. Neonatal fat mass (%) was measured in a subset of neonates born to T2DM women. RESULTS: GLUT1 protein expression was increased (p = 0.001) and GLUT4 decreased (p = 0.006) in BM from T2DM. MVM FATP6 expression was increased (p = 0.02) and correlated with birth weight in both T2DM and NGT groups (r = 0.65, p = 0.02). BM FATP6 expression was increased (p = 0.01) in T2DM. In MVM of T2DM placentas, SNAT1 expression was increased (p = 0.05) and correlated with birth weight (r = 0.84, p = 0.004); SNAT2 was increased (p = 0.01), however System A transporter activity was not different between groups. MVM LAT1 expression was increased (p = 0.01) in T2DM and correlated with birth weight (r = 0.59, p = 0.04) and neonatal fat mass (r = 0.76, p = 0.06). CONCLUSION: In pregnancies complicated by T2DM placental protein expression of transporters for glucose, amino acids and fatty acids is increased, which may contribute to increased fetal growth and neonatal adiposity.


Subject(s)
Adiposity , Birth Weight , Carrier Proteins/biosynthesis , Diabetes Mellitus, Type 2/metabolism , Gene Expression Regulation , Placenta/metabolism , Pregnancy Proteins/biosynthesis , Pregnancy in Diabetics/metabolism , Adult , Female , Humans , Infant, Newborn , Male , Pregnancy
6.
Int J Mol Sci ; 21(23)2020 Nov 24.
Article in English | MEDLINE | ID: mdl-33255257

ABSTRACT

Progressive fetal infection/inflammation is strongly associated with neural injury after preterm birth. We aimed to test the hypotheses that progressively developing fetal inflammation leads to neuroinflammation and impaired white matter development and that the histopathological changes can be detected using high-field diffusion tensor magnetic resonance imaging (MRI). Chronically instrumented preterm fetal sheep at 0.7 of gestation were randomly assigned to receive intravenous saline (control; n = 6) or a progressive infusion of lipopolysaccharide (LPS, 200 ng intravenous over 24 h then doubled every 24 h for 5 days to induce fetal inflammation, n = 7). Sheep were killed 10 days after starting the infusions, for histology and high-field diffusion tensor MRI. Progressive LPS infusion was associated with increased circulating interleukin (IL)-6 concentrations and moderate increases in carotid artery perfusion and the frequency of electroencephalogram (EEG) activity (p < 0.05 vs. control). In the periventricular white matter, fractional anisotropy (FA) was increased, and orientation dispersion index (ODI) was reduced (p < 0.05 vs. control for both). Histologically, in the same brain region, LPS infusion increased microglial activation and astrocyte numbers and reduced the total number of oligodendrocytes with no change in myelination or numbers of immature/mature oligodendrocytes. Numbers of astrocytes in the periventricular white matter were correlated with increased FA and reduced ODI signal intensities. Astrocyte coherence was associated with increased FA. Moderate astrogliosis, but not loss of total oligodendrocytes, after progressive fetal inflammation can be detected with high-field diffusion tensor MRI.


Subject(s)
Gliosis/diagnostic imaging , Inflammation/diagnostic imaging , Leukoencephalopathies/diagnostic imaging , Magnetic Resonance Imaging , Animals , Gliosis/physiopathology , Gliosis/veterinary , Inflammation/physiopathology , Inflammation/veterinary , Leukoencephalopathies/physiopathology , Leukoencephalopathies/veterinary , Sheep , White Matter/diagnostic imaging , White Matter/physiopathology
7.
Case Rep Obstet Gynecol ; 2019: 4290145, 2019.
Article in English | MEDLINE | ID: mdl-30906607

ABSTRACT

Myotonic dystrophy is an autosomal-dominant disorder. Its congenital type is the most severe form, with respiratory failure that can be a life-threatening event after birth. There are no antenatal treatments that can improve neonatal outcomes of myotonic dystrophy. We treated a fetus with congenital myotonic dystrophy by administering indomethacin to the 31-year-old Japanese mother affected by myotonic dystrophy and polyhydramnios. We observed increased fetal breathing movement and a reduction of the amniotic fluid volume. The baby was born at 37 weeks and discharged from the neonatal intensive care unit with a favorable outcome. Indomethacin treatment is likely to improve fetal lung function and to control the amniotic fluid volume. This report emphasizes the importance of further investigations regarding the optimal management of congenital myotonic dystrophy.

8.
eNeurologicalSci ; 11: 17-19, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29928713

ABSTRACT

We have reported an autopsy case of neuromyelitis optica (NMO) that exhibited persisting active inflammatory lesions in the central nervous system (CNS) despite a 45-year-long treatment with oral corticosteroids. To our knowledge, our case had received the longest course of maintenance treatment. This case study suggests that the current treatment of NMO with immunosuppressive agents may offer a good prospect for improving life expectancy. On the other hand, it also suggest that microscopic active lesions which were clinically silent and difficult to detect by neurological examination or MRI studies may persist in the CNS in patients with NMO, despite prolonged and continuous immunosuppressive treatment.

9.
Am J Physiol Regul Integr Comp Physiol ; 315(2): R205-R217, 2018 08 01.
Article in English | MEDLINE | ID: mdl-29561649

ABSTRACT

Magnesium sulfate (MgSO4) is recommended for preterm neuroprotection, preeclampsia, and preterm labor prophylaxis. There is an important, unmet need to carefully test clinical interventions in both sexes. Therefore, we aimed to investigate cardiovascular and neurophysiological adaptations to MgSO4 during normoxia and asphyxia in preterm male and female fetal sheep. Fetuses were instrumented at 98 ± 1 days of gestation (term = 147 days). At 104 days, unanesthetized fetuses were randomly assigned to intravenous MgSO4 ( n = 12 female, 10 male) or saline ( n = 13 female, 10 male). At 105 days fetuses underwent umbilical cord occlusion for up to 25 min. Occlusions were stopped early if mean arterial blood pressure (MAP) fell below 8 mmHg or asystole occurred for >20 s. During normoxia, MgSO4 was associated with similar reductions in fetal heart rate (FHR), EEG power, and movement in both sexes ( P < 0.05 vs. saline controls) and suppression of α- and ß-spectral band power in males ( P < 0.05 vs. saline controls). During occlusion, similar FHR and MAP responses occurred in MgSO4-treated males and females compared with saline controls. Recovery of FHR and MAP after release of occlusion was more prolonged in MgSO4-treated males ( P < 0.05 vs. saline controls). During and after occlusion, EEG power was lower in MgSO4-treated females ( P < 0.05 vs. saline controls). In conclusion, MgSO4 infusion was associated with subtle sex-specific effects on EEG spectral power and cardiac responses to asphyxia in utero, possibly reflecting sex-specific differences in interneuronal connectivity and regulation of cardiac output.


Subject(s)
Asphyxia/drug therapy , Brain/drug effects , Cardiovascular System/drug effects , Hemodynamics/drug effects , Magnesium Sulfate/pharmacology , Neuroprotective Agents/pharmacology , Adaptation, Physiological , Animals , Arterial Pressure/drug effects , Asphyxia/diagnostic imaging , Asphyxia/physiopathology , Brain/physiopathology , Brain Waves/drug effects , Cardiovascular System/physiopathology , Disease Models, Animal , Electroencephalography , Female , Fetal Movement/drug effects , Gestational Age , Heart Rate, Fetal/drug effects , Male , Prenatal Diagnosis/methods , Sex Factors , Sheep, Domestic
10.
J Physiol ; 596(23): 6093-6104, 2018 12.
Article in English | MEDLINE | ID: mdl-29315570

ABSTRACT

KEY POINTS: Fetal heart rate variability is a critical index of fetal wellbeing. Suppression of heart rate variability may provide prognostic information on the risk of hypoxic-ischaemic brain injury after birth. In the present study, we report the evolution of fetal heart rate variability after both mild and severe hypoxia-ischaemia. Both mild and severe hypoxia-ischaemia were associated with an initial, brief suppression of multiple measures of heart rate variability. This was followed by normal or increased levels of heart rate variability during the latent phase of injury. Severe hypoxia-ischaemia was subsequently associated with the prolonged suppression of measures of heart rate variability during the secondary phase of injury, which is the period of time when brain injury is no longer treatable. These findings suggest that a biphasic pattern of heart rate variability may be an early marker of brain injury when treatment or intervention is probably most effective. ABSTRACT: Hypoxia-ischaemia (HI) is a major contributor to preterm brain injury, although there are currently no reliable biomarkers for identifying infants who are at risk. We tested the hypothesis that fetal heart rate (FHR) and FHR variability (FHRV) would identify evolving brain injury after HI. Fetal sheep at 0.7 of gestation were subjected to either 15 (n = 10) or 25 min (n = 17) of complete umbilical cord occlusion or sham occlusion (n = 12). FHR and four measures of FHRV [short-term variation, long-term variation, standard deviation of normal to normal R-R intervals (SDNN), root mean square of successive differences) were assessed until 72 h after HI. All measures of FHRV were suppressed for the first 3-4 h in the 15 min group and 1-2 h in the 25 min group. Measures of FHRV recovered to control levels by 4 h in the 15 min group, whereas the 25 min group showed tachycardia and an increase in short-term variation and SDNN from 4 to 6 h after occlusion. The measures of FHRV then progressively declined in the 25 min group and became profoundly suppressed from 18 to 48 h. A partial recovery of FHRV measures towards control levels was observed in the 25 min group from 49 to 72 h. These findings illustrate the complex regulation of FHRV after both mild and severe HI and suggest that the longitudinal analysis of FHR and FHRV after HI may be able to help determine the timing and severity of preterm HI.


Subject(s)
Brain Injuries/physiopathology , Heart Rate, Fetal , Hypoxia-Ischemia, Brain/physiopathology , Animals , Female , Fetus/physiology , Male , Pregnancy , Sheep
12.
Am J Physiol Regul Integr Comp Physiol ; 311(5): R949-R956, 2016 11.
Article in English | MEDLINE | ID: mdl-27654399

ABSTRACT

The role of cholinergic and ß-adrenergic activity in mediating fetal cardiovascular recovery from brief repeated episodes of asphyxia consistent with established labor, remains unclear. In this study, we tested the effect of cholinergic and ß-adrenergic blockade on the fetal chemoreflex and fetal heart rate (FHR) overshoot responses during brief repeated asphyxia at rates consistent with early or active labor. Chronically instrumented fetal sheep at 0.85 of gestation received either i.v. atropine sulfate (cholinergic blockade, n=8) or vehicle (n=7) followed by 3 x 1-minute umbilical cord occlusions repeated every 5 minutes (1:5; consistent with early labor), or i.v. propranolol hydrochloride (ß-adrenergic blockade, n=6) or vehicle (n=6) followed by 3 x 2-minute occlusions repeated every 5 minutes (2:5; consistent with active labor). In vehicle-controls, 1:5 occlusions were associated with rapid and sustained FHR decelerations followed by rapid return of FHR to baseline values after release of the occlusion. Cholinergic blockade abolished FHR decelerations during occlusions and caused FHR overshoot after release of the occlusion (P<0.05 vs. control 1:5). In vehicle-controls, 2:5 occlusions caused rapid and sustained FHR decelerations followed by FHR overshoot after release of the occlusion. ß-adrenergic blockade was associated with greater reduction in FHR during occlusions and attenuated FHR overshoot (P<0.05 vs. control 2:5). These data demonstrate that the FHR overshoot pattern after asphyxia is mediated by a combination of attenuated parasympathetic activity and increased ß-adrenergic stimulation of the fetal heart.

13.
Carbohydr Polym ; 149: 51-9, 2016 Sep 20.
Article in English | MEDLINE | ID: mdl-27261729

ABSTRACT

Herein, we report a comparative study of silver coated anionic cellulose nanocomposite before (CMC-Ag) and after (AgNPs/CMC) chemical reduction for antibacterial activity. Cellulose nanofibers were prepared by deacetylation of electrospun cellulose acetate nanofibers, which were then treated with sodium chloroacetate to prepare anionic cellulose nanofibers (CMC). Aqueous AgNO3 solution with different concentrations was employed to produce nanofiber composites. To obtain AgNPs/CMC, the resultant Ag/CMC nanofibers were chemically reduced with NaBH4. The nanocomposites were characterized by FE-SEM, FTIR, XPS and SEM-EDS. Antimicrobiality tests were conducted using S. aureus and Escherichia coli bacteria following standard test method JIS L1902, 2008. The EDS results confirmed higher silver content in CMC-Ag nanofibers than AgNPs/CMC nanofibers. The antimicrobial test and EDS results demonstrated higher silver release (larger halo width) by the former in comparison to later which confers better antimicrobiality by CMC-Ag nanofibers.


Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Cellulose/chemistry , Cellulose/pharmacology , Nanocomposites/chemistry , Nanofibers/chemistry , Silver/chemistry , Escherichia coli/drug effects , Staphylococcus aureus/drug effects
14.
J Physiol ; 594(17): 4711-25, 2016 09 01.
Article in English | MEDLINE | ID: mdl-27328617

ABSTRACT

A distinctive pattern of recurrent rapid falls in fetal heart rate, called decelerations, are commonly associated with uterine contractions during labour. These brief decelerations are mediated by vagal activation. The reflex triggering this vagal response has been variably attributed to a mechanoreceptor response to fetal head compression, to baroreflex activation following increased blood pressure during umbilical cord compression, and/or a Bezold-Jarisch reflex response to reduced venous return from the placenta. Although these complex explanations are still widespread today, there is no consistent evidence that they are common during labour. Instead, the only mechanism that has been systematically investigated, proven to be reliably active during labour and, crucially, capable of producing rapid decelerations is the peripheral chemoreflex. The peripheral chemoreflex is triggered by transient periods of asphyxia that are a normal phenomenon associated with all uterine contractions. This should not cause concern as the healthy fetus has a remarkable ability to adapt to these repeated but short periods of asphyxia. This means that the healthy fetus is typically not at risk of hypotension and injury during uncomplicated labour even during repeated brief decelerations. The physiologically incorrect theories surrounding decelerations that ignore the natural occurrence of repeated asphyxia probably gained widespread support to help explain why many babies are born healthy despite repeated decelerations during labour. We propose that a unified and physiological understanding of intrapartum decelerations that accepts the true nature of labour is critical to improve interpretation of intrapartum fetal heart rate patterns.


Subject(s)
Heart Rate, Fetal , Labor, Obstetric , Animals , Asphyxia/physiopathology , Baroreflex/physiology , Female , Fetus/physiology , Head/physiology , Humans , Hypovolemia/physiopathology , Pregnancy
15.
Support Care Cancer ; 22(4): 905-9, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24240649

ABSTRACT

PURPOSE: Patients with gastrointestinal cancer who were receiving moderately emetogenic chemotherapy (MEC) were switched from granisetron, a first-generation 5-hydroxytryptamine-3 receptor antagonist, to palonosetron at our hospital. In the present study, we compared effectiveness before and after switching antiemetic treatment. METHODS: Among patients who were receiving MEC for gastrointestinal cancer, we prospectively observed 46 patients given granisetron and 46 given palonosetron. To allow adverse reactions to be graded in accordance with the Common Terminology Criteria for Adverse Events, version 4.0, a questionnaire designed at our hospital was used to compare the occurrence of delayed nausea and vomiting between patients who received granisetron (GRA group) and those who received palonosetron (PAL group). RESULTS: The incidence of delayed nausea was significantly lower in the PAL group (8.7%, 4/46; p < 0.01) than in the GRA group (37%, 17/46). Delayed vomiting developed in five patients (10.9%) in the GRA group, but did not occur in the PAL group. On the basis of the results of multivariate analysis, young age, female gender, and the use of granisetron were significant risk factors for delayed nausea. CONCLUSION: Our survey showed that palonosetron effectively controls delayed nausea caused by MEC for gastrointestinal cancer.


Subject(s)
Antiemetics/therapeutic use , Antineoplastic Agents/adverse effects , Gastrointestinal Neoplasms/drug therapy , Isoquinolines/therapeutic use , Nausea/prevention & control , Quinuclidines/therapeutic use , Vomiting/prevention & control , Adult , Aged , Aged, 80 and over , Antineoplastic Agents/therapeutic use , Female , Granisetron/therapeutic use , Humans , Male , Middle Aged , Nausea/chemically induced , Palonosetron , Prospective Studies , Surveys and Questionnaires , Vomiting/chemically induced
16.
Bioorg Med Chem ; 20(14): 4310-5, 2012 Jul 15.
Article in English | MEDLINE | ID: mdl-22705023

ABSTRACT

In this study, we synthesized a simple but efficient quencher-free molecular beacon tethering 7-hydroxycoumarin on D-threoninol based on its pK(a) change. The pK(a) of 7-hydroxycoumarin in a single strand was determined as 8.8, whereas that intercalated in the duplex was over 10. This large pK(a) shift (more than 1.2) upon hybridization could be attributed to the anionic and hydrophobic microenvironment inside the DNA duplex. Because 7-hydroxycoumarin quenches its fluorescence upon protonation, the emission intensity of the duplex at pH 8.5 was 1/15 that of the single strand. We applied this quenching mechanism to the preparation of a quencher-free molecular beacon by introducing the dye into the middle of the stem part. In the absence of the target, the stem region formed a duplex and fluorescence was quenched. However, when the target was added, the molecular beacon opened and the dye was deprotonated. As a result, the emission intensity of the molecular beacon with the target was 10 times higher than that without the target. Accordingly, a quencher-free molecular beacon utilizing the pK(a) change was successfully developed.


Subject(s)
Intercalating Agents/chemistry , Umbelliferones/chemistry , Amino Alcohols/chemistry , Butylene Glycols/chemistry , DNA/chemistry , DNA/metabolism , Hydrogen-Ion Concentration , Intercalating Agents/chemical synthesis , Kinetics , Nucleic Acid Denaturation , Nucleic Acid Hybridization , Protons
17.
J Phys Chem A ; 109(1): 40-3, 2005 Jan 13.
Article in English | MEDLINE | ID: mdl-16839087

ABSTRACT

Ultrasonic absorption measurements in the frequency range from 0.8 to 220 MHz were carried out in aqueous solutions of pentylammonium chloride (PEACL) and hexylammonium chloride (HEACL) with beta-cyclodextrin (beta-CD) at pH approximately 7.2 and 25 degrees C. A single relaxational absorption was attributed to a perturbation of a chemical relaxation associated with the formation of a complex between beta-CD and the alkylammonium chlorides. The rate and equilibrium constants for the complexation reaction were determined from the concentration dependence of the relaxation frequency. Increasing the chain length of the alkylammonium ion led to an increase in the stability of the complex and slowed the exit rate of the ion from the beta-CD cavity. The standard volume change of the reaction was obtained from a maximum absorption per wavelength and was attributed to water molecules being expelled from the cavity with concomitant alkylammonium ion insertion.


Subject(s)
Quaternary Ammonium Compounds/chemistry , Ultrasonics , beta-Cyclodextrins/chemistry , Alkylation , Ions/chemistry , Solutions , Spectrum Analysis , Temperature , Thermodynamics
18.
J Acoust Soc Am ; 115(5 Pt 1): 2325-30, 2004 May.
Article in English | MEDLINE | ID: mdl-15139644

ABSTRACT

Ultrasonic absorption coefficients in the frequency range of 0.8-95 MHz were measured in aqueous solutions of L-methionine or L-norleucine (guest) in the presence and absence of beta-cyclodextrin (beta-CD, host) at 25 degrees C. A single relaxational absorption was observed only in the solutions containing the guest and host. The ultrasonic relaxation was attributed to a perturbation of a chemical equilibrium associated with an interaction between beta-CD and the amino acid to form the host-guest complex. The kinetic and thermodynamic parameters in the system of L-norleucine with beta-CD were determined from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. Because of the concentration independence of the relaxation frequency in L-methionine system with beta-CD, the equilibrium constant and the standard volume change of the complexation reaction were estimated first from the concentration dependence of maximum absorption per wavelength, and subsequently the rate constants were calculated with the help of the estimated equilibrium constant and the observed relaxation frequency. The results obtained in this study were compared with those for systems of beta-CD with other amino acids or alcohols having comparable hydrophobicity.


Subject(s)
Cyclodextrins/metabolism , Methionine/metabolism , Norleucine/metabolism , beta-Cyclodextrins , Absorption/physiology , Cyclodextrins/chemistry , Hydrogen-Ion Concentration , Methionine/chemistry , Norleucine/chemistry , Ultrasonics
19.
Ind Health ; 40(1): 36-41, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11926513

ABSTRACT

The relation between exposure and sensitization or the appearance of symptoms of the eyes and airways was investigated in a cross-sectional study on 32 workers from a plant using epoxy resin with a mixture of hexahydrophthalic anhydride (HHPA) and methylhexahydrophthalic anhydride (MHHPA) as a hardener. The main component in the hardener was HHPA, and the geometric mean concentrations of HHPA in the workplaces were extremely low (<40 microg/m3) in recent years, compared to the Occupational Exposure Limit-Ceiling for phthalic anhydride (2 mg/m3). However, specific IgE antibody to HHPA was detected in serum from 8 (25%) out of the workers: of those, 5 workers experienced symptoms of the eyes and nose during work (group sensitized symptomatic (SS)) and 3 workers did not (group sensitized nonsymptomatic (SN)). The other 24 workers had no signs of sensitization and did not complain of work-related symptoms. Based on occupational history and anamnestic data, it was concluded that one subject in the SS group and all the subjects in the SN group had been sensitized by higher exposures in the past. The symptoms of 4 subjects in the SS group occurred only when carrying out short-time, particular tasks (15-30 min) a few times a day, such as the resin mixing procedures, manual application of the resin, or opening of ovens. High peak exposures were estimated to have occurred during the particular tasks. Our results suggest that short-time peak exposures may have a great impact on the development of specific IgE or work-related symptoms. Therefore, to minimize the risk of sensitization and work-related symptoms, a reduction of exposure during particular tasks with high peak exposures, along with a decrease in mean 8-h time-weighted average exposure, should be achieved.


Subject(s)
Air Pollutants, Occupational/adverse effects , Drug Hypersensitivity/etiology , Epoxy Resins/adverse effects , Occupational Diseases/chemically induced , Phthalic Acids/adverse effects , Phthalic Anhydrides/adverse effects , Adult , Analysis of Variance , Asthma/chemically induced , Female , Humans , Immunoglobulin E/analysis , Male , Middle Aged , Occupational Diseases/immunology , Occupational Exposure , Rhinitis/chemically induced
20.
Ind Health ; 40(1): 63-5, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11926518

ABSTRACT

In an electronics plant, a new one-component naphthalene type epoxy resin was used as an adhesive for reinforcing a circuit board. The resinous part of the adhesive consisted of diglycidyl ether of bisphenol A (DGEBA) and 1,6-bis(2,3-epoxypropoxy)naphthalene type epoxy resins. The hardener was methylhexahydrophthalic anhydride (MHHPA). Of 54 workers, 15 (27.8%) were diagnosed to have work-related dermatitis but were not patch tested. Therefore, it was impossible to determine the specific agent responsible for the worker's symptoms or to distinguish between allergic and irritant contact dermatitis. They worked without protective gloves until they started to develop skin symptoms. The hands were the commonly affected region (13 out of 15 cases). The latent period of dermatitis was very short (mean 2.2 weeks). Of these, 10 cases (66.7%) received medication for dermatitis, and 9 cases (60%) were transferred to other work. The work-related skin symptoms were closely related to the specific tasks, i.e., filling dispensers with the adhesive and manual application of the adhesive to a portion of a circuit board using a dispenser. For occupational hygiene reasons, contact with epoxy resins should be minimized by taking all possible measures into use, including protective gloves. Further studies are required to clarify the allergenicity of 1,6-bis(2,3-epoxypropoxy)naphthalene, since very little is known about the mechanism through which it leads to the symptoms of dermatitis.


Subject(s)
Adhesives/adverse effects , Dermatitis, Contact/etiology , Dermatitis, Occupational/etiology , Epoxy Compounds/adverse effects , Adolescent , Adult , Dermatitis, Contact/prevention & control , Dermatitis, Occupational/prevention & control , Female , Humans , Male , Occupational Exposure
SELECTION OF CITATIONS
SEARCH DETAIL
...