Relationship between optimism, emotional intelligence, and academic resilience of nursing students: the mediating effect of self-directed learning competency

Background

The evolution toward future education following the 4th industrial revolution and the coronavirus disease 2019 (COVID-19) pandemic have changed nursing education dramatically. Online classes have become a new paradigm of education, and are expected to develop and be maintained in various forms even after the end of COVID-19. Therefore, attention is focused on finding ways to improve learners' achievements in a distance learning environment. This study aimed to examine the mediating effects of self-directed learning competency on the relationships between optimism, emotional intelligence and academic resilience among nursing students.

Methods

A cross-sectional descriptive design was conducted using convenience sampling of 195 nursing students in South Korea. Data were analyzed with descriptive statistics, Pearson's correlation coefficients, multiple regression, and mediation analysis using SPSS/WIN 26.0 program.

Results

There were significant positive correlations among self-directed learning competency, optimism, emotional intelligence and academic resilience. The self-directed learning competency acts as a mediator in explaining relationship between optimism, emotional intelligence and academic resilience, respectively.

Conclusion

This study provides the evidence for the role of self-directed learning competency in the relationship between optimism, emotional intelligence and academic resilience in nursing students. Rapid changes in education are inevitable due to changes in clinical settings and the impact of repeated infectious disease outbreaks including the COVID-19 pandemic. This study suggests strengthening positive psychology and self-directed learning capability of nursing students as a strategy to prepare for changes in education and clinical areas.

Factors associated with teaching efficacy among nurse educators in hospital settings

AIMS AND OBJECTIVES

The objective of this study was to examine differences in personal characteristics, core practice competency and role stress according to levels of teaching efficacy among clinical nurse educators working in general hospitals.

BACKGROUND

In the clinical setting, successful adaptation to instruction among practicing clinical nurse educators is challenging.

DESIGN

Secondary analysis of data through a cross-sectional study design was adopted.

METHODS

Originally, 565 nurses were recruited from general hospitals; 364 were included in this study. Participants were nurses with more than 1 year of experience in various settings from 16 general hospitals wherein nursing students trained for clinical practicum in five cities in South Korea. Self-reported data were collected via the Teaching Efficacy, Core Practice Competency and Perceived Stress Scales assessing clinical education-related teaching efficacy, core practice competency and role stress. In the analyses, comparison between nurses with high and low teaching efficacy was conducted. We have followed through the EQUATOR (e.g. STROBE) research checklist for the preparation of this manuscript.

RESULTS

According to univariate analysis, levels of teaching efficacy were shown to be higher with age, longer clinical careers, in those undergoing a doctoral course or with a doctorate, previous experience in providing clinical education and enrolment in continuing education for clinical education. In the multivariate analysis, enrolment in continuing education for clinical education, assessment and intervention skills, critical thinking skills, teaching skills and role ambiguity were associated with level of teaching efficacy among nurse educators.

CONCLUSION

Based on the results of this study, we recommend that nursing administrators should foster the recognition of personal characteristics in potential clinical nurse educators or preceptors with high teaching efficacy.

RELEVANCE TO CLINICAL PRACTICE

Nurses should be supported by providing them with opportunities for professional development to enhance teaching efficacy.

Metacognitive beliefs predict early response to pharmacological treatment in patients with obsessive-compulsive disorder

RATIONALE

Metacognitions, beliefs that monitor or control thoughts and coping, are considered to be important components for development and maintenance of obsessive-compulsive disorder (OCD).

OBJECTIVES

This study prospectively investigated whether metacognitive beliefs can predict early treatment response after serotonin reuptake inhibitor (SRI) initiation in patients with OCD.

METHODS

Drug-naïve or medication-free patients with OCD (N = 156) were assessed for various characteristics, including metacognitions. In total, 132 patients were followed for 4 weeks, and their clinical responses to pharmacological treatment were assessed using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Early treatment response was defined as a 20% or greater reduction from the baseline Y-BOCS score at 4 weeks. Logistic and linear regression analyses were performed to identify major determinants for the early treatment outcome.

RESULTS

Among participants with OCD, 53 patients (40.15%) were early responders. The logistic regression model revealed two significant predictors, age (beta = - 0.113, p < 0.001) and "positive beliefs about worry," which refers to metacognitive beliefs concerning the benefits of engaging in worry (beta = - 0.067, p = 0.001), for identifying early responders. Moreover, in the linear regression model, lower "positive beliefs about worry" was also shown as a significant predictor for the degree of better early improvement (beta = - 0.566, p = 0.001).

CONCLUSIONS

These results suggest that lower metacognition of "positive beliefs about worry" predicts improvement of obsessive-compulsive symptoms seen early on in the SRI treatment, and that pathological metacognitive belief would lead to delayed response to SRI treatment in OCD.

Characteristics of Autonomic Activity and Reactivity During Rest and Emotional Processing and Their Clinical Correlations in Somatic Symptom Disorder

OBJECTIVE

Altered autonomic nervous system activity is considered to be involved in the pathophysiology of somatic symptom disorder (SSD). This study aimed to investigate whether patients with SSD have disturbed autonomic activity during rest and reactivity to emotional processing and whether altered autonomic nervous system correlates with clinical characteristics and interoceptive accuracy in SSD.

METHODS

We recruited 23 patients with SSD and 20 healthy controls. Heart rate variability (HRV) was assessed during recording at rest and during performance of an emotional face dot-probe task. Alpha-amylase responses were also assessed. Patients with SSD completed a self-assessment survey and heart beat perception task, which reflects interoceptive awareness.

RESULTS

Patients with SSD had lower low-frequency HRV, high-frequency HRV, standard deviation of normal to normal R-R intervals (SDNN), and proportion of successive R-R intervals greater than 50 milliseconds (pNN50) at rest (p < .05). The reactivity scores (during-task activity minus resting activity) for SDNN and pNN50 were significantly different between patients with SSD and controls (SDNN: p = .013; pNN50: p = .008). In addition, resting HRV parameters (low-frequency, high-frequency, SDNN, pNN50) correlated with heart beat perception error (p < .01) in patients with SSD. No significant differences in α-amylase activity were found.

CONCLUSIONS

Our findings showed that patients with SSD have altered resting-state autonomic activity and reactivity to emotional processing, and the resting-state autonomic activity correlated with their interoceptive awareness. These findings suggest that disturbed interactions between the autonomic nervous, affective, and interoceptive systems may be involved in the pathophysiology of SSD.

Multidimensional impulsivity as a mediator of early life stress and alcohol dependence

Early life stress (ELS) leads to increased susceptibility to serious psychiatric problems such as alcohol dependence, but the mechanisms through which ELS affects alcohol dependence are unclear. We investigated the mediating role of multi-dimensional impulsivity in the associations between ELS and alcohol dependence. 330 male patients with alcohol dependence (mean age = 48.39) completed self-rating scales of ELS and several self-report measures of impulsivity as well as balloon analogue risk task (BART). After classifying different dimensions of impulsivity using factor analysis, structural equation modeling was conducted to test the mediation effects of impulsivity between ELS and alcohol dependence severity and social onset of hazardous drinking. Among the participants, 64.8%, 42.1% and 47.9% reported at least one episode of childhood maltreatment, sexual abuse and parental conflict, respectively. Response impulsivity-sensation seeking, reflection impulsivity and aggression partially mediated the association between ELS and severity of alcohol dependence (CFI = 0.902 and RMSEA = 0.079). Reflection impulsivity dimension partially mediated the association between ELS and social onset of hazardous drinking (CFI = 0.939, RMSEA = 0.091). These finding imply that stabilizing vulnerabilities such as reflection impulsivity via intervention programs that target young individuals with ELS may be helpful in delaying the onset of hazardous drinking and prevent alcohol dependence.

Reliability and validity of the Korean-language version of the Communication Function Classification System in children with cerebral palsy

PURPOSE

The Communication Function Classification System (CFCS) and Viking Speech Scale (VSS) are useful systems for describing the broad communication function and speech intelligibility, respectively, of children with cerebral palsy (CP). The aims of this study were to determine the reliability and validity of the Korean version of the CFCS and also to investigate the association between the CFCS and the VSS and other functional classifications for children with CP.

MATERIALS AND METHODS

Participants were 50 children with CP (33 males, 17 females; mean age 7.2 years, range 4-16 years) recruited from a rehabilitation hospital. We analysed the interrater and intrarater reliabilities of the Korean version of the CFCS and VSS between parents, a physiatrist, and a speech-language pathologist (SLP). The social function domain of the Paediatric Evaluation of Disability Inventory was assessed to examine the concurrent validity of the CFCS and VSS.

RESULTS

The intrarater reliabilities of the CFCS and VSS were excellent in a physiatrist (ƙ = 0.92, ƙ = 0.94, respectively) and an SLP (ƙ = 0.98, ƙ = 0.98) and very good in parents (ƙ = 0.87, ƙ = 0.89). The interrater reliability of the CFCS and VSS was very good between the physiatrist and SLP (ƙ = 0.87, ƙ = 0.89) and good between parents and the SLP (ƙ = 0.63, ƙ = 0.78) and between parents and the physiatrist (ƙ = 0.61, ƙ = 0.76). The CFCS and VSS were strongly related with the social function domain of Paediatric Evaluation of Disability Inventory. In addition, we found very strong associations between the VSS and CFCS.

CONCLUSIONS

The Korean version of the CFCS is a valid and reliable tool to classify communication ability and is strongly associated with the VSS, a reliable tool to classify speech intelligibility.

Oxytocin receptor gene polymorphisms exert a modulating effect on the onset age in patients with obsessive-compulsive disorder

The oxytocin receptor (OXTR) is a potential candidate in the pathophysiology of obsessive-compulsive disorder (OCD). The present study investigated the association between common single-nucleotide polymorphism (SNPs) of the OXTR gene and the affected status of OCD or distinct clinical subtypes of OCD including the age at onset and symptom dimensions. Ten SNPs of OXTR were examined in 615 patients with OCD and 581 healthy controls. Single-marker and haplotype-based association analyses were conducted. While OXTR variants were not associated with the affected status of OCD or its clinical symptom dimensions, rs2268493 (p=0.00185) and rs13316193 (p=0.00461) of the OXTR gene were associated with the age at onset in patients with OCD. In addition, in haplotype-based association analyses, there was a significant association between the OXTR gene and the onset age in patients with OCD. In particular, the G-C-G haplotype of rs2268493-rs2254298-rs11316193 and the T-G-A haplotype of rs237887-rs2268490-rs4686301 were positively associated with late-onset OCD. Our results suggest that common variants of OXTR may exert a modulating effect on the onset age in OCD pathophysiology. The potential involvement of the oxytocin system in the development and expression of OCD warrants further longitudinal research.

Common variants of HTR3 genes are associated with obsessive-compulsive disorder and its phenotypic expression

Evidence from literature supports the existence of associations between serotonin-related genetic variants and obsessive-compulsive disorder (OCD), but few studies have explored the involvement of serotonin receptor type 3 genes (HTR3) in OCD. To identify whether HTR3 variability affects an individual’s susceptibility to OCD, we examined 10 HTR3 variants in 596 individuals with OCD and 599 controls. A significant difference existed in the genotypic distribution of the HTR3B variant rs1176744 between individuals with OCD and controls (odds ratio [OR] = 0.74, 95% confidence interval [CI] = 0.60–0.91, P = 0.0043). A protective haplotype in HTR3B was also associated with OCD (OR = 0.77, CI = 0.63–0.95, permutated P = 0.0179). Analyses of OCD sub-phenotypes demonstrated significant associations between rs3758987 and early onset OCD in male subjects (OR = 0.49, CI = 0.31–0.79, P = 0.0031) and among rs6766410, rs6443930, and the cleaning dimension in female subjects (OR = 0.36, CI = 0.18–0.69, P = 0.0016 and OR = 0.47, CI = 0.29–0.79, P = 0.0030, respectively). Additionally, rs6766410 was related to contamination-based disgust in OCD (P = 0.0044). These results support that common HTR3 variants are involved in OCD and some of its clinical phenotypes.

Alexithymia and perfectionism traits are associated with suicidal risk in patients with obsessive-compulsive disorder

BACKGROUND

There is limited evidence on suicidality and its associated factors in patients with obsessive-compulsive disorder (OCD). The present study investigated the potential contributing traits such as alexithymia and perfectionism and clinical risk factors including symptom dimensions associated with high suicidality in OCD patients.

METHODS

A total of 81 patients with OCD were included (mean age: 28.89 years, SD=7.95 years, 62% men). Suicidal risk was assessed using the Scale for Suicide Ideation and history taking. To assess alexithymia and perfectionism, the Toronto Alexithymia Scale-20 and the Measure of Constructs Underlying Perfectionism were applied. Clinical characteristics of OCD were assessed with the Yale-Brown Obsessive-Compulsive Scale, the Dimensional Obsessive-Compulsive Scale, and the Montgomery-Asberg Depression Rating Scale. Among OCD patients, 37% had a history of previous suicidal attempt, and 56.8% had current suicidal ideation.

RESULTS

Those with lifetime suicide attempts scored significantly higher for alexithymia and ego-dystonic perfectionism than those without such history. In the binary logistic regression analysis, high score for alexithymia and the responsibility for harm, injury, or bad luck were significant determinants for lifetime suicide attempts. As for current suicide ideation, ego-dystonic perfectionism and the dimension of unacceptable thought were significant predictors of suicidal risk.

LIMITATIONS

The classification of suicidal risk and personality traits relied on self-report measures.

CONCLUSION

The present findings indicate that personality traits such as alexithymia and perfectionism may contribute to high suicidality in patients with OCD, and patients suffering with unacceptable thoughts need to be assessed more carefully for warning signs of suicide.

Strongly Metallic Electron and Hole 2D Transport in an Ambipolar Si-Vacuum Field Effect Transistor

We report experiment and theory on an ambipolar gate-controlled Si(111)-vacuum field effect transistor where we study electron and hole (low-temperature 2D) transport in the same device simply by changing the external gate voltage to tune the system from being a 2D electron system at positive gate voltage to a 2D hole system at negative gate voltage. The electron (hole) conductivity manifests strong (moderate) metallic temperature dependence with the conductivity decreasing by a factor of 8 (2) between 0.3 K and 4.2 K with the peak electron mobility (∼18  m2/V s) being roughly 20 times larger than the peak hole mobility (in the same sample). Our theory explains the data well using random phase approximation screening of background Coulomb disorder, establishing that the observed metallicity is a direct consequence of the strong temperature dependence of the effective screened disorder.

Thermoelectric detection of chiral heat transport in graphene in the quantum Hall regime

We report measurements of heat transport along the edge conducting channels in monolayer graphene in the integer quantum Hall regime. Hot charge carriers are injected to the edge channels, and the thermoelectric voltage is measured at a distance along the edge from the heat injection point. We confirm that heat transport in graphene in the quantum Hall regime is chiral and the thermoelectric signal is correlated with the charge conductance of ballistic transport, following the Mott relation. The thermoelectric signal decays with distance from the heater, indicating that carriers are partially thermalized during edge transmission.

Theory of 2D transport in graphene for correlated disorder

We theoretically revisit graphene transport properties as a function of carrier density, taking into account possible correlations in the spatial distribution of the Coulomb impurity disorder in the environment. We find that the charged impurity correlations give rise to a density-dependent graphene conductivity, which agrees well qualitatively with the existing experimental data. We also find, quite unexpectedly, that the conductivity could increase with increasing impurity density if there is sufficient interimpurity correlation present in the system. In particular, the linearity (sublinearity) of graphene conductivity at lower (higher) gate voltage is naturally explained as arising solely from impurity correlation effects in the Coulomb disorder.

Induction of apoptosis by the ginsenoside Rh2 by internalization of lipid rafts and caveolae and inactivation of Akt

BACKGROUND AND PURPOSE

Lipid rafts and caveolae are membrane microdomains with important roles in cell survival signalling involving the Akt pathway. Cholesterol is important for the structure and function of these microdomains. The ginsenoside Rh2 exhibits anti-tumour activity. Because Rh2 is structurally similar to cholesterol, we investigated the possibility that Rh2 exerted its anti-tumour effect by modulating rafts and caveolae.

EXPERIMENTAL APPROACH

A431 cells (human epidermoid carcinoma cell line) were treated with Rh2 and the effects on cell apoptosis, raft localization and Akt activation measured. We also examined the effects of over-expression of Akt and active-Akt on Rh2-induced cell death.

KEY RESULTS

Rh2 induced apoptosis concentration- and time-dependently. Rh2 reduced the levels of rafts and caveolae in the plasma membrane and increased their internalization. Furthermore, Akt activity was decreased and consequently, Akt-dependent phosphorylation of Bad, a pro-survival protein, was decreased whereas the pro-apoptotic proteins, Bim and Bax, were increased upon Rh2 treatment. Unlike microdomain internalization induce by cholesterol depletion, Rh2-mediated internalization of rafts and caveolae was not reversed by cholesterol addition. Also, cholesterol addition did not restore Akt activation or rescue cells from Rh2-induced cell death. Rh2-induced cell death was attenuated in MDA-MB-231 cells over-expressing either wild-type or dominant-active Akt.

CONCLUSIONS AND IMPLICATIONS

Rh2 induced internalization of rafts and caveolae, leading to Akt inactivation, and ultimately apoptosis. Because elevated levels of membrane rafts and caveolae, and Akt activation have been correlated with cancer development, internalization of these microdomains by Rh2 could potentially be used as an anti-cancer therapy.

Collective modes of the massless dirac plasma

We develop a theory for the long-wavelength plasma oscillation of a collection of charged massless Dirac particles in a solid, as occurring, for example, in doped graphene layers, interacting via the long-range Coulomb interaction. We find that the long-wavelength plasmon frequency in such a doped massless Dirac plasma is explicitly nonclassical in all dimensions with the plasma frequency being proportional to 1/sqrt[variant Planck's over 2pi]. We also show that the long-wavelength plasma frequency of the D-dimensional superlattice made from such a plasma does not agree with the corresponding D + 1-dimensional bulk plasmon frequency. We compare and contrast such Dirac plasmons with the well-studied regular palsmons in metals and doped semiconductors which manifest the usual classical long-wavelength plasma oscillation.

Screening, Kohn anomaly, Friedel oscillation, and RKKY interaction in bilayer graphene

We calculate the screening function in bilayer graphene (BLG) in both the intrinsic (undoped) and the extrinsic (doped) regimes within the random phase approximation, comparing our results with the corresponding single layer graphene and the regular two-dimensional electron gas. We find that the Kohn anomaly is strongly enhanced in BLG. We also discuss the Friedel oscillation and the RKKY interaction, which are associated with the nonanalytic behavior of the screening function at q=2k(F). We find that the Kohn anomaly, the Friedel oscillation, and the RKKY interaction are all qualitatively different in the BLG compared with the single layer graphene and the two-dimensional electron gas.

Measurement of scattering rate and minimum conductivity in graphene

The conductivity of graphene samples with various levels of disorder is investigated for a set of specimens with mobility in the range of 1-20x10(3) cm2/V sec. Comparing the experimental data with the theoretical transport calculations based on charged impurity scattering, we estimate that the impurity concentration in the samples varies from 2-15x10(11) cm(-2). In the low carrier density limit, the conductivity exhibits values in the range of 2-12e2/h, which can be related to the residual density induced by the inhomogeneous charge distribution in the samples. The shape of the conductivity curves indicates that high mobility samples contain some short-range disorder whereas low mobility samples are dominated by long-range scatterers.

Transport and percolation in a low-density high-mobility two-dimensional hole system

We present a study of the temperature and density dependence of the resistivity of an extremely high quality two-dimensional hole system grown on the (100) surface of GaAs. For high densities in the metallic regime (p > or approximately4x10;{9} cm;{-2}), the nonmonotonic temperature dependence ( approximately 50-300 mK) of the resistivity is consistent with temperature dependent screening of residual impurities. At a fixed temperature of T=50 mK, the conductivity versus density data indicate an inhomogeneity driven percolation-type transition to an insulating state at a critical density of 3.8x10;{9} cm;{-2}.

Density dependent exchange contribution to partial differential mu/ partial differential n and compressibility in graphene

We calculate partial differentialmu/ partial differentialn (where mu=chemical potential and n=electron density), which is associated with the compressibility, in graphene as a function of n, within the Hartree-Fock approximation. The exchange-driven Dirac-point logarithmic singularity in the quasiparticle velocity of intrinsic graphene disappears in the extrinsic case. The calculated renormalized partial differentialmu/ partial differentialn in extrinsic graphene on SiO2 has the same n;{-(1/2)} density dependence but is 20% larger than the inverse bare density of states, a relatively weak effect compared to the corresponding parabolic-band case. We predict that the renormalization effect can be enhanced to about 50% by changing the graphene substrate.

Effects of mRg2, a mixture of ginsenosides containing 60% Rg2, on the ultraviolet B-induced DNA repair synthesis and apoptosis in NIH3T3 cells

Ginseng has been used worldwidely as a traditional medicine of Asian countries for treatment of various diseases including cancer. The purpose of this study was to determine the effect of ginseng saponin mRg2, a mixture of ginsenosides containing 60% Rg2, on the repair and apoptosis of ultraviolet B (UVB)-exposed NIH3T3 cells. When cells were exposed to UVB and then incubated with normal growth medium for 48 h, cell viability, as determined by trypan blue exclusion assay decreased to about 25%. However, when mRg2 was included in the postincubation medium, the UVB-induced loss of cell viability was significantly reduced as compared with that postincubated in normal growth medium. 4,6-diamidino-2-phenylindole (DAPI) staining showed that postincubation of the UVB-exposed cells in medium containing mRg2 significantly reduced the apoptotic nuclear fragmentation. Interestingly, when cells were preincubated with mRg2 for 24 h and then exposed to various doses of UV, the amount of repair synthesis significantly increased as compared with those in cells exposed to UVB alone. Western blot analysis indicated that the mRg2 postincubation after UVB exposure potentiated the level of p53 and p21. The level of Triton nonextractable proliferating cell nuclear antigen (PCNA) also remained elevated by mRg2 postincubation. All these results suggest that mRg2 protects cells against UVB-induced genotoxicity by increasing DNA repair and decreasing apoptosis, in possible association with the modulation of protein levels involved in cell cycle arrest or progression.

Carrier transport in two-dimensional graphene layers

Carrier transport in gated 2D graphene monolayers is considered in the presence of scattering by random charged impurity centers with density n(i). Excellent quantitative agreement is obtained (for carrier density n>10(12) cm(-2)) with existing experimental data. The conductivity scales linearly with n/n(i) in the theory. We explain the experimentally observed asymmetry between electron and hole conductivities, and the high-density saturation of conductivity for the highest mobility samples. We argue that the experimentally observed saturation of conductivity at low density arises from the charged impurity induced inhomogeneity in the graphene carrier density which becomes severe for n less, similarn(i) approximately 10(12) cm(-2).

Quasi-two-dimensional diluted magnetic semiconductor systems

We develop a theory for two-dimensional diluted magnetic semiconductor systems (e.g., Ga(1-x)Mn(x)As layers) where the itinerant carriers mediating the ferromagnetic interaction between the impurity local moments, as well as the local moments themselves, are confined in a two-dimensional layer. The theory includes exact spatial disorder effects associated with the random local moment positions within a disordered RKKY lattice field theory description. We predict the ferromagnetic transition temperature (T(c)) as well as the nature of the spontaneous magnetization. The theory includes disorder and finite carrier mean-free path effects as well as the important correction arising from the finite temperature RKKY interaction, finding a strong density dependence of T(c) in contrast to the simple virtual crystal approximation.

Temperature dependent weak field Hall resistance in two-dimensional carrier systems

Using the Drude-Boltzmann semiclassical transport theory, we calculate the weak-field Hall resistance of a two-dimensional system at low densities and temperatures, assuming carrier scattering by screened random charged impurity centers. The temperature-dependent 2D Hall coefficient shows striking nonmonotonicity in strongly screened systems, and, in particular, we qualitatively explain the recent puzzling experimental observation of a decreasing Hall resistance with increasing temperature in a dilute 2D hole system. We predict that the impurity scattering limited Hall coefficient will eventually increase with temperature at higher temperatures.

Two-dimensional metal-insulator transition as a percolation transition in a high-mobility electron system

By carefully analyzing the low temperature density dependence of 2D conductivity in undoped high-mobility n-GaAs heterostructures, we conclude that the 2D metal-insulator transition in this 2D electron system is a density inhomogeneity driven percolation transition due to the breakdown of screening in the random charged impurity disorder background. In particular, our measured conductivity exponent of approximately 1.4 approaches the 2D percolation exponent value of 4/3 at low temperatures and our experimental data are inconsistent with there being a zero-temperature quantum critical point in our system.

Disordered RKKY lattice mean field theory for ferromagnetism in diluted magnetic semiconductors

We develop a lattice mean field theory for ferromagnetic ordering in diluted magnetic semiconductors by taking into account the spatial fluctuations associated with random disorder in the magnetic impurity locations and the finite mean free path associated with low carrier mobilities. Assuming a carrier-mediated indirect RKKY exchange interaction among the magnetic impurities, we find substantial deviation from the extensively used continuum Zener model Weiss mean field predictions. Our theory allows accurate analytic predictions for Tc and provides simple explanations for a number of observed anomalies, including the non-Brillouin function magnetization curves, the suppressed low-temperature magnetization saturation, and the dependence of Tc on conductivity.

Frictional drag in dilute bilayer 2D hole systems

We develop a theory for frictional drag between two 2D hole layers in a dilute bilayer GaAs hole system, including effects of hole-hole and hole-phonon interactions. Our calculations suggest significant enhancement of hole drag transresistivity over the corresponding electron drag results. This enhancement originates from the exchange induced renormalization of the single-layer compressibility and the strong dependence of single-layer conductivity on density. We also address the effect of hole-phonon interaction on the drag temperature dependence. Our calculated results are in reasonable quantitative agreement with recent experimental observations.

Resistivity of dilute 2D electrons in an undoped GaAs heterostructure

We report resistivity measurements from 0.03 to 10 K in a dilute high mobility 2D electron system. Using an undoped GaAs/AlGaAs heterojunction in a gated field-effect transistor geometry, a wide range of densities, 0.16 x 10(10) to 7.5 x 10(10) cm(-2), are explored. For high densities, the results are quantitatively shown to be due to scattering by acoustic phonons and impurities. In an intermediate range of densities, a peak in the resistivity is observed for temperatures below 1 K. This nonmonotonic resistivity can be understood by considering the known scattering mechanisms of phonons, bulk, and interface ionized impurities. Still lower densities appear insulating to the lowest temperature measured.

Inflammatory orbital pseudotumor with infratemporal fossa extension mimicking temporomandibular joint dysfunction

Inflammatory orbital pseudotumor is a benign space-occupying lesion of unknown origin that involves all or part of the fatty tissue within the orbit. Occasionally the disease may extend into the middle cranial, the pterygopalatine, and the infratemporal fossa through the various foramina of the orbit, although extension into the infratemporal fossa is very rare. We present a case which extends into the infratemporal fossa through the inferior orbital fissure, resulting in presenting symptoms mimicking temporomandibular joint dysfunction.

The development of fetal surgery

The history of fetal surgery features an absolute dependency upon the possibility of diagnosis before birth. Powerful new imaging methods, the techniques of sampling amniotic fluid and fetal tissue, and modern molecular genetics for the prenatal diagnosis of various congenital diseases have removed the veil of secrecy from the fetus. Even though most prenatally detected congenital malformations can be managed after maternal transport, a few simple anatomic defects require fetal surgery, albeit with predictably poor results. The understanding of intrauterine physiology and pathophysiology in several congenital malformations has been worked out in animal model study, and the natural history of congenital defects revealed by prenatal observations on human fetuses. Selection criteria for intrauterine intervention have been developed. Over the last two decades, surgical techniques for open and endoscopic fetal surgery have been defined and anesthesia and tocolysis for fetal surgery improved. As we enter the 21st century, this field of surgery will surely expand.

Biliary atresia associated with meconium peritonitis caused by perforation of small bowel atresia

BACKGROUND/PURPOSE

This report describes our experiences with 5 cases of biliary atresia associated with meconium peritonitis caused by perforation of small bowel atresia.

METHODS

A review of medical records was undertaken in an effort to recognize cases of biliary atresia associated with meconium peritonitis.

RESULTS

Five patients of 171 with biliary atresia (2.9%) were detected to have meconium peritonitis caused by perforation of small bowel atresia. The biliary atresia was not suspected during the initial operation for meconium peritonitis. Total parenteral nutrition (TPN) made it difficult to make an early differential diagnosis of biliary atresia because of the presence of TPN-associated cholestatic jaundice, and the Roux-en-Y limb used for hepatic portoenterostomy could not be made long enough to prevent cholangitis caused by preexisting short bowel. The main complications were severe, intractable cholangitis, short bowel syndrome with malnutrition; TPN-associated liver injury; and wound problems. Two patients died of ascending cholangitis, 1 patient of liver failure that was exacerbated by TPN-associated liver injury, and 1 patient is awaiting a liver transplant. Only 1 patient is in good health, being anicteric and showing normal growth and development.

CONCLUSIONS

Biliary atresia is evidently closely associated with meconium peritonitis caused by perforation of small bowel atresia. The management of these patients is more difficult than that of patients with the usual form of biliary atresia, because of the necessity for a long period of TPN and the combined short bowel syndrome. The ideal management of these conditions has yet to be determined.

Fistula-in-ano in infants: is nonoperative management effective?

PURPOSE

Recently, a number of studies have reported positive results from the nonoperative management of fistula-in-ano in infancy, although it has not been of use in all patients. The purpose of this study was to discern the effective treatment methods of fistula-in-ano in infants.

METHODS

A retrospective review was done of 310 children who required operative management for fistula-in-ano or perianal abscess between January 1991 and July 2000. Eighteen patients displayed an onset of symptoms at less than 1 year of age and a duration of symptoms longer than 12 months. The authors analyzed these patients' medical records.

RESULTS

All patients were boys. The mean duration of the symptoms was 26.6 +/- 27.5 months. Fourteen patients had shown an onset of symptoms at less than 6 months of age. The longest duration was 10 years. The patients showed conservative periods of over 12 months because their parents did not want them to undergo surgery. The disease in these patients followed 2 patterns. One (6 patients) was an onset of symptoms followed by a silent fistula-in-ano state. The other (12 patients) was an onset of symptoms followed by an intermittent relapse of inflammation. All patients underwent fistulotomy, and none of them had recurrent fistula during the follow-up period.

CONCLUSIONS

Although the advantages of a nonoperative management of fistula-in-ano in infants include the avoidance of general anesthesia and surgical intervention, the lesions cannot be cured by a period of conservation. Surgical management is more effective in respect to the time factor.

Multiple cemento-ossifying fibroma: report of an 18-year follow-up

Multiple cemento-ossifying fibroma is a very rare jaw lesion. A unique case is reported involving a 43-year-old Korean woman with rapidly growing, multiple cemento-ossifying fibromas in all four quadrants over an 18-year period which resulted in severe facial deformity and orbital compression.

Tailgut cyst in a neonate

Tailgut cyst is a rare lesion of developmental origin located in the retrorectal space, which usually presents as a multilocular cystic mass. It is usually found in adults, and neonatal cases are extremely rare. The authors report a tailgut cyst in a neonate that was found by prenatal ultrasonogram, which was like a teratoma in gross appearance.

Parallel magnetic field induced giant magnetoresistance in low density quasi-two-dimensional layers

We provide a possible theoretical explanation for the recently observed giant positive magnetoresistance in high mobility low density quasi-two-dimensional electron and hole systems. Our explanation is based on the strong coupling of the parallel field to the orbital motion arising from the finite layer thickness and the large Fermi wavelength of the quasi-two-dimensional system at low carrier densities.

Biliary atresia in neonates and infants: triangular area of high signal intensity in the porta hepatis at T2-weighted MR cholangiography with US and histopathologic correlation

PURPOSE

To correlate a triangular area of high signal intensity in the porta hepatis on T2-weighted magnetic resonance (MR) cholangiograms of biliary atresia with ultrasonographic (US) and histopathologic findings in a portal mass observed during a Kasai procedure.

MATERIALS AND METHODS

Twenty-one consecutive neonates and infants (age range, 13-88 days; mean age, 59 days) with cholestasis underwent US and single-shot MR cholangiography. In 12 patients with biliary atresia diagnosed at histopathologic examination, MR cholangiographic findings in the porta hepatis were correlated with US and histopathologic findings in the portal mass.

RESULTS

At US, eight of the 12 patients had round, linear, or tubular hypoechoic portions within a triangular cord; MR cholangiography revealed a triangular area of high signal intensity confined to the porta hepatis. Histopathologic examination of the portal mass revealed a cystic or cleftlike lesion surrounded by loose myxoid mesenchyme and platelike fetal bile ducts. Neither the large cystic lesion without ductal epithelium nor the small cleftlike lesion with scanty epithelium demonstrated bile staining. Similar areas of high signal intensity were not seen on T2-weighted images in the remaining patients (four with biliary atresia and nine with neonatal hepatitis).

CONCLUSION

In biliary atresia, T2-weighted single-shot MR cholangiography can show a triangular area of high signal intensity in the porta hepatis that may represent cystic dilatation of the fetal bile duct.

Peripheral sympathetic dysfunction in patients with Parkinson's disease without autonomic failure is heart selective and disease specific. taki@med.kanazawa-u.ac.jp

The study was undertaken to investigate by means of iodine-123-labelled metaiodobenzylguanidine (MIBG) scintigraphy the peripheral sympathetic function in patients with Parkinson's disease (PD) without autonomic failure and in patients with related neurodegenerative diseases with parkinsonism. Seventy patients (33 men and 37 women, mean age 63+/-9.7 years) with parkinsonism and ten control subjects underwent MIBG scintigraphy. Of these 70 patients, 41 were diagnosed as having idiopathic PD, 9 multiple system atrophy (MSA), 6 progressive supranuclear palsy (PSP) and 2 corticobasal degeneration (CBD); the remaining 12 were diagnosed as having neurodegenerative disease with parkinsonism (P-nism) that did not meet the diagnostic criteria of any specific disease. Cardiac planar and tomographic imaging studies and subsequent whole-body imaging were performed 20 min and 3 h after the injection of 111 MBq MIBG. The early MIBG heart to mediastinum (H/M) ratio in PD (1.61+/-0.29) was significantly lower than that in the control group (2.24+/-0.14, P<0.01), P-nism (2.15+/-0.31, P<0.01), MSA (2.08+/-0.31, P<0.05) and PSP (2.30+/-0.24, P<0.01). The delayed H/M ratio in PD (1.47+/-0.34) was also significantly lower than that in the control group (2.37+/-0.14, P<0.01), P-nism (2.13+/-0.38, P<0.01), PSP (2.36+/-0.36, P<0.01) and MSA (2.17+/-0.36, P<0.01). In patients with PD, early and delayed H/M ratios were significantly decreased in disease stages I, II and III (established using the Hoehn and Yahr criteria) as compared with control subjects, and there were no significant differences among the stages. Only PD showed a significantly higher washout rate (WR) than that in the control subjects (27%+/-8.0% vs. 11%+/-4.2%, P<0.01). Early and delayed uptake ratios of the lung, parotid gland, thyroid gland, liver and femoral muscles in each of the patient groups were not significantly different from those in control subjects. Only the early and delayed uptake ratios of the lower leg muscles in MSA were significantly lower than those in the control group (P<0.05).

IN CONCLUSION

In patients with PD without autonomic failure, only cardiac MIBG uptake was severely reduced in the earliest phase of the disease (stage I). Parkinsonian syndromes other than PD did not demonstrate significant reduction in MIBG uptake in any organs except for the lower legs in MSA. In patients with PD without autonomic failure, reduction in MIBG uptake occurs selectively in the heart; this is considered to be a specific finding for PD and useful for the differential diagnosis of the parkinsonian syndromes.

Preoperative assessment of residual hepatic functional reserve using 99mTc-DTPA-galactosyl-human serum albumin dynamic SPECT

Preoperative assessment of residual hepatic functional reserve offers important strategic information for hepatic resection. To predict the postoperative residual liver function, we assessed the value of hepatic 99mTc-diethylenetriamine pentaacetic acid-galactosyl-human serum albumin (99mTc-GSA) clearance estimated by dynamic SPECT analysis.

METHODS

We investigated 114 consecutive patients with liver disease, including 55 hepatectomy cases. One minute after injection of 185 MBq 99mTc-GSA, 15 serial dynamic SPECT images were obtained every minute. The initial five sets of SPECT images were analyzed by Patlak plot to estimate the sequential initial hepatic 99mTc-GSA clearance (mL/min) as an index of hepatic function. The sum of hepatic 99mTc-GSA clearance of the segments immune from resection was categorized as predicted residual 99mTC-GSA clearance. In the hepatectomy cases, scintigraphy was performed before and 37 +/- 10 d after the operation.

RESULTS

Good correlation was observed between the total hepatic 99mTc-GSA clearance and conventional hepatic function tests: plasma retention rate of iodocyanine green (ICG) at 15 min (ICG R15), r = -0.600, P < 0.0001, n = 94; plasma disappearance rate of ICG (K ICG), r = 0.670, P < 0.0001, n = 83; cholinesterase, r = 0.539, P < 0.0001, n = 121; serum albumin, r = 0.421, P = 0.0001, n = 123; and hepaplastin test, r = 0.456, P < 0.0001, n = 120. There was good correlation between the predicted residual 99mTc-GSA clearance and the postoperative total hepatic 99mTc-GSA clearance in patients who underwent segmentectomy or lobectomy (r = 0.84, P < 0.0001, n = 28) and between the pre- and postoperative total hepatic 99mTc-GSA clearance in patients who underwent subsegmentectomy (r = 0.91, P < 0.0001, n = 25). Five patients who had postoperative complications due to hepatic insufficiency (2 patients died of postoperative hepatic failure within 2 mo after operation) showed significantly lower predicted residual 99mTc-GSA clearance compared with the patients without complications (90.3 +/- 37.2 versus 320.9 +/- 158.8 mL/min; P < 0.005).

CONCLUSION

The total hepatic 99mTC-GSA clearance reflected hepatic function. In addition, preoperative predicted residual hepatic 99mTc-GSA clearance was a good indicator of postoperative hepatic function and early prognosis. 99mTc-GSA dynamic SPECT is assumed to be a useful method for determining the surgical strategy in patients with hepatic tumor and especially in patients with hepatic dysfunction.

[99mTc-GSA dynamic SPECT for regional hepatic functional reserve estimation: assessment of clinical value for hepatic resection]

We assessed the clinical value of three-dimensional functional mapping method employing GSA dynamic SPECT for the estimation of residual hepatic functional reserve before hepatic resection. Seventy-two consecutive patients of liver tumor were recruited in this study. Thirty-seven underwent segmentectomy or lobectomy and 35 did subsegmentectomy. GSA studies were carried out in all 72 patients before operation. Postoperative studies were performed in 70 patients about 1 month after operation, and 2 patients died of postoperative hepatic failure early after operation. In the preoperative study, liver functional images were divided into 4 segments according to liver anatomy and segmental GSA clearance was analyzed. The sum of GSA clearance of the segments immune from resection were calculated as predicted residual GSA clearance. Two patients who showed poor predicted residual hepatic GSA clearance died of postoperative hepatic failure within two months after operation (extended right lobectomy). There were good correlations between pre- and postoperative total liver clearance in patients underwent subsegmentectomy (r = 0.900, p < 0.0001, n = 35), and between predicted residual clearance and postoperative total clearance in patients underwent segmentectomy or lobectomy (r = 0.799, p < 0.0001, n = 35). After hepatic resection, there seemed to be discrepancies between hepatic volume expansion and functional restoration in some patients. Mean GSA clearance (clearance per unit volume) apparently decreased after operation in patients whose residual volume ratio (preoperative predicted residual liver volume/preoperative total liver volume) were less than 50% (p < 0.01, n = 12). These results suggested that three-dimensional functional mapping method employing GSA dynamic SPECT can provide quantitative information of postoperative hepatic function and reserve before hepatic resection. Changes of mean GSA clearance after hepatic resection suggested that hepatic function per unit volume changes in the process of hepatic regeneration.

[99mTc-GSA dynamic SPECT for regional hepatic functional reserve estimation: assessment of quantification]

For the estimation of regional hepatic functional reserve, we produced a three-dimensional hepatic functional mapping method employing 99mTc-GSA dynamic SPECT. In this analyzing protocol, we applied Patlak plot for the estimation of the liver uptake parameter of GSA, which is named hepatic GSA clearance, because it is relatively simple and suitable for matrix by matrix analysis. In this study, we assessed the physiological implication of estimated parameters and the clinical value of this analyzing method for hepatic functional reserve estimation. After venous injection of 185 MBq of GSA (3 mg), fifteen sequential sets of SPECT data were acquired for 15 minutes. First 5 sets (minutes) SPECT images were analyzed by Patlak plot and hepatic GSA clearance (ml/min) was obtained in each matrix. The sum of hepatic GSA clearance in each matrix (total hepatic GSA clearance) was calculated as an index of whole liver functional reserve. Total hepatic GSA clearance was compared with receptor index or effective blood flow (EHBF) of whole liver which were analyzed by Direct Integral Linear Least Square Regression (DILS) method for the assessment of the physiological implications of hepatic GSA clearance. The clinical value of total hepatic GSA clearance was assessed in comparisons with the conventional hepatic function test. A very good correlations were observed between total hepatic GSA clearance and receptor index (r = 0.935, p < 0.0001, n = 49), whereas the correlations between total hepatic GSA clearance and EHBF were not significant. Significant correlations were also observed between total hepatic GSA clearance and the conventional hepatic function tests, such as choline esterase (r = 0.517, p = 0.0001, n = 47), albumin (r = 0.612, p < 0.0001, n = 49), hepaplastin test (r = 0.539, p < 0.0001, n = 47), ICG R15 (r = -0.616, p < 0.0001, n = 37). These results suggested that hepatic GSA clearance strongly reflects hepatic receptor function and this parameter seemed to be useful for the hepatic functional reserve estimation.

Multiple intestinal ulcerations and perforations secondary to methicillin-resistant Staphylococcus aureus enteritis in infants

PURPOSE

The aim of this study was to define a distinctive clinical entity of multiple intestinal ulcerations and perforations in infants.

METHODS

Two infants underwent abdominal exploration for surgical abdomen and were noted to have multiple intestinal ulcerations and perforations. A peculiar and unique surgical finding, numerous transverse linear ulcerations scattered along the entire small intestine, prompted us to search for similar instances. Five similar cases were additionally identified by members of the Korean Association of Pediatric Surgeons. The clinical courses, the surgical findings, and the results of bacterial cultures were reviewed. As well, the tissues of resected intestines were examined histopathologically.

RESULTS

The characteristics of this entity are as follows. (1) It usually occurs in infants who have been treated with broad-spectrum antibiotics. (2) Despite broad-spectrum antibiotic treatment, diarrhea and abdominal distension developed progressively and deteriorated. (3) Histological evaluation showed mucosal ulcers with neutrophil infiltration, submucosal microabscesses, and colonies of Gram-positive cocci. (4) Methicillin-resistant Staphylococcus aureus (MRSA) was the predominant organism cultured from the body fluid. (5) Only two cases, the completely resected one and the one immediately treated postoperatively with vancomycin, survived.

CONCLUSIONS

This entity is caused by multiple intestinal ulcerations and perforations secondary to MRSA enteritis in infants. It has a high mortality rate because of its difficult diagnosis. However, early recognition of this entity can lead to successful treatment.

Simple scintigraphic parameters with Tc-99m galactosyl human serum albumin for clinical staging of chronic hepatocellular dysfunction

Technetium-99m labeled diethylenetriaminepentaacetic acid (DTPA)-galactosyl human serum albumin (GSA) has been used for hepatocellular functional evaluation. This study proposed new and simple parameters to overcome the limitations of conventional parameters, and they were applied to the clinical staging of chronic liver dysfunction. The study group consisted of 93 patients including 81 with liver dysfunction and 12 control patients. In addition to the two conventional parameters, namely, receptor index (LHL15 = liver count divided by the sum of liver and heart counts at 15 minutes) and clearance index (HH15 = heart count at 15 minutes divided by the heart count at 3 minutes), 6 new parameters for Tc-99m GSA uptake and clearance were generated. The conventional receptor index of LHL15 showed a large variation depending on the size of region of interest (ROI) over the heart. The LHL15 normalized by the ROI size (nLHL15) showed more stable data and a better separation of mild liver dysfunction. A hyperbolic relationship between the LHL15 and HH 15 changed to a linear relationship by using the nLHL15 index. The combination of the liver to heart average count ratio at 15 minutes (LH 15) and T-half (minute) of the heart count also could differentiate each stage well. In conclusion, the use of the ROI-area normalized nLHL is recommended instead of the conventional LHL15. The indices of LH15 and T-half could be alternatively used as practical parameters for clinical staging in liver function.

Absent myocardial iodine-123-BMIPP uptake and platelet/monocyte CD36 deficiency

Global absence of myocardial 123I-15-(p-iodophenyl)-3-(R,S)-methyl pentadecanoic acid (BMIPP) uptake is occasionally noted, and it reflects myocardial long-chain fatty acid uptake abnormality. CD36, a membrane glycoprotein expressed on platelet, monocyte and endothelial cells, may contribute to myocardial fatty acid transport, and its deficiency has been reported in a small subset of the population. We hypothesized that CD36 deficiency may be related to absent myocardial BMIPP uptake. Thus, we investigated CD36 expression of platelet/monocyte in patients with absent myocardial BMIPP uptake.

METHODS

Peripheral blood of 7 patients with global absence of myocardial BMIPP uptake (3 of 7 patients in one family) and 3 control subjects were examined in flow cytometric analysis. Platelet/monocyte surface CD36 was detected by using OKM5, an anti-CD36 mouse monoclonal antibody.

RESULTS

There were no apparent relationships between specific clinical symptoms and absent myocardial BMIPP uptake. None of the blood samples of the 7 patients were stained with OKM5 on the platelet/monocyte cell surface, indicating that all of these patients were Type I CD36-deficient subjects. In contrast, all the control subjects showed normal staining.

CONCLUSION

The fact that rare Type I CD36 deficiency was observed in all patients with absent myocardial BMIPP uptake suggests that CD36 plays a role in the myocardial long-chain fatty acid uptake process in humans.

Colon perforation in hyperimmunoglobulin E syndrome

Colon perforation from hyperimmunoglobulin E syndrome is very rare, and only one case has been reported in the English-language literature. Herein, the authors report another case of colon perforation experienced in hyperimmunoglobulin E syndrome. The patient was an 8-year-old girl with frequent infection, eczematoid dermatitis, and an increased serum level of immunoglobulin E. During admission, panperitonitis developed caused by colon perforation. Treatment was resection of the perforated segment of the colon and a double-barrel colostomy. The patient has been doing well 18 months after treatment.