Fatal Primary Amebic Meningoencephalitis in Nebraska: Case Report and Environmental Investigation, August 2022

Primary amebic meningoencephalitis (PAM) is a rare and lethal infection caused by Naegleria fowleri. We report an epidemiological and environmental investigation relating to a case of PAM in a previously healthy boy age 8 years. An interview of the patient's family was conducted to determine the likely exposure site and to assess risk factors. Data from the United States Geological Survey site at Waterloo, NE, on the Elkhorn River were used to estimate water temperature and streamflow at the time and site of exposure. Data from the National Weather Service were used to estimate precipitation and ambient air temperature at the time and site of exposure. Despite conventional treatment, the patient died 2 days after hospital admission. The patient participated in recreational water activities in the Elkhorn River in northeastern Nebraska 5 days before symptom onset. In the week before exposure, water and ambient air high temperatures reached annual highs, averaging 32.4°C and 35.8°C, respectively. The day before infection, 2.2 cm of precipitation was reported. Streamflow was low (407 ft3/s). Infections in several northern states, including Nebraska, suggest an expanding geographic range of N. fowleri transmission, which may lead to increased incidence of PAM in the United States. Similar environmental investigations at suspected exposure sites of future cases will allow data aggregation, enabling investigators to correlate environmental factors with infection risk accurately.

Initial stage of cubic GaN for heterophase epitaxial growth induced on nanoscale v-grooved Si(001) in metal-organic vapor-phase epitaxy

The initial stages of the nucleation of cubic (c-) GaN in heterophase epitaxy on a Si v-groove are investigated. Growth of GaN on a nanoscale {111}-faceted v-groove fabricated into a Si(001) substrate proceeds in the hexagonal (h-) phase that induces a secondary v-groove replicating the substrate topography with two opposing {0001} facets. The secondary v-groove is then orientationally mismatched at the junction of the h-GaN facets (h -h junction) resulting in structural instability. This instability is relieved either by the formation of voids that reduce the actual junction area or by the transition to c-phase (h-c transition) suppressing further extension of the h-h junction. The distribution of voids that is locally affected by the island growth mode of h-GaN on Si(111) and the imperfection in the groove geometry impacts the initial stage of heterophase epitaxy. Primarily, The h-c transition is observed as a non-local phenomenon; it occurs homogeneously and simultaneously along the bottom of the entire secondary groove and forms a one-dimensional (1D) seed layer except for some interruptions where the h-h junction is defected by gaps or incomplete voids. Between these interruptions, epitaxy retains a single crystal but results in a series of c-GaN nanodots on the seed layer with large fluctuation in size and spacing. The adatom incorporation observed in this heterophase epitaxy is a 1D analog to the wetting of a substrate followed by the self-assembly in conventional quantum dot epitaxy. The surface morphology of the c-GaN nanodots is governed by the faceting mostly composed of (001)- and (11n)-orientations and the roughening between these facets that ultimately affect the morphology of the final top surface of the c-III-N. The interruptions interfere with the homogeneity of the h-c transition and can cause antiphase defects and mosaicity. Based on experimental results, a solution to improve these issues is proposed.

Analysis of the stability of InGaN/GaN multiquantum wells against ion beam intermixing

Ion-induced damage and intermixing was evaluated in InGaN/GaN multi-quantum wells (MQWs) using 35 keV N(+) implantation at room temperature. In situ ion channeling measurements show that damage builds up with a similar trend for In and Ga atoms, with a high threshold for amorphization. The extended defects induced during the implantation, basal and prismatic stacking faults, are uniformly distributed across the quantum well structure. Despite the extremely high fluences used (up to 4 × 10(16) cm(-2)), the InGaN MQWs exhibit a high stability against ion beam mixing.

Time Resolved Photoluminescence Spectroscopy on GaN Epitaxial Layers

Free and bound exciton luminescences as well as donor-acceptor pair recombination of GaN epitaxial layers on 6H-SiC and sapphire substrates were investigated using time integrated and time resolved photoluminescence measurements at low temperatures. Lifetimes are determined for the donor bound exciton at 3.4722eV and for two acceptor bound excitons with energies of 3.4672eV and 3.459eV. Luminescences between 3.29eV and 3.37eV are identified as due to excitons deeply bound to centers located near the substrate-epilayer interface.

Localized Donors in Gan: Spectroscopy Using Large Pressures

Properties of GaN and its alloys are strongly controlled by impurities and strain. Using large hydrostatic and biaxial pressure we identify the role of donor dopants and stress induced fields. The doping of Si and 0 as relevant representatives of group-IV and group-VI impurities are studied in Raman spectroscopy. For pressures above 20 GPa we find that oxygen induces a strongly localized gap state while Si continues to behave as a hydrogenic donor. Such a DX-like behavior of 0 indicates and corresponds to doping limitations in AIGaN alloys. The site specific (ON, SiGa) formation of a gap-state is attributed to bond strengths of the respective neighbors. In photoreflection of pseudomorphic GaInN we observe pronounced Franz-Keldysh oscillations corresponding to piezoelectric fields of 0.6 MV/cm. An observed redshift of the luminescence is found to originate in electric field induced tailstates. A reduced but similar effect is expected for GaN possibly explaining observations of persistent photoconductivity in a wide range of materials.

Electron-Phonon Scattering in Si-Doped GaN

Phonon-plasmon scattering in non-resonant Raman spectroscopy is used to determine the free electron concentration in Si doped GaN films. For various doping concentration and variable temperature the correlation with magneto-transport data is established. The freeze-out of the carrier concentration at low temperature is thus observed in a purely optical detection scheme. We observe a very long transient time of several hours for the carrier concentration as a reaction to temperature variation. This indicates an indirect capture and emission process with a very small cross section. The value of the Faust-Henry coefficient is determined.

Biological relevance of ion energy in performance of human endothelial cells on ion-implanted flexible polyurethane surfaces

To improve the biocompatibility of polyurethane (PUR), we modified the surface by irradiation with different ions (Carbon; C, Oxygen; O, Nitrogen; N, or Argon; Ar) at 0.3-50 keV energy and doses of 1,00E+13 - 1,00E+15 ions/cm(2). The effects of ion implantation using different ion energies and densities were observed on adhesion, proliferation, and viability of human umbilical vein endothelial cells (HUVECs). The long-term in vitro stability of ion-implanted PUR was also investigated. Ion irradiation moderately affected the surface roughness (R(a)), but strongly enhanced the work of adhesion (W(a)). Cell adhesion was markedly improved on O-, N-, and Ar-, but not on C-implanted PUR surfaces. Medium ion energies and lower ion doses produced the best HUVEC attachment and proliferation, indicating the importance of choosing the proper range of energy applied during ion irradiation. In addition, apoptosis rates were significantly reduced when compared with unmodified PUR (uPUR). N implantation significantly protected the surface, although C implantation led to stronger surface erosions than on uPUR. In total, ion implantation on flexible PUR surfaces strongly improved the material surface characteristics and biocompatibility. Electron beam ion implantation within an appropriate energy window is thus a key to improving flexible PUR surfaces for clinical use to support endothelial cell performance. Thus, it can contribute to designing small-diameter grafts, which are in great demand, towards vascular tissue engineering applications.

High-density exposure therapy for obsessive-compulsive inpatients: a 1-year follow-up

BACKGROUND

This study evaluates the effects of individual high-density exposure (2-3 weeks, all day) plus response prevention therapy on 85 unselected inpatients suffering from obsessive-compulsive disorder (OCD).

METHODS

Twenty-eight therapist practitioners performed treatment.

RESULTS

At 1-year follow-up, self-ratings indicated that patients on average felt much improved. Impairment by both obsessions and compulsions was significantly reduced (p < 0.001 in each case), and OCD symptoms as assessed by two OCD questionnaires had also decreased significantly, as had depressiveness and overall symptomatology (all p < 0.001). Defining improvements as >30% successes, as done in other OCD treatment outcome studies, success rates were 68 and 69%, respectively, for the two OCD questionnaire scores, 75% for self-rated impairment by obsessions and 84.5% for compulsions, 85.6% for overall psychopathology (General Symptom Index), and 75% for depressiveness (Beck Depression Inventory). Effect sizes were >1 SD for all of the measures included.

CONCLUSIONS

We conclude that long-term effects for high-density treatment of unselected OCD patients bring about as good results as treatments with exposure and response prevention performed with selected patient samples in a research context.

The IMMUTANS variegation locus of Arabidopsis defines a mitochondrial alternative oxidase homolog that functions during early chloroplast biogenesis

Nuclear gene-induced variegation mutants provide a powerful system to dissect interactions between the genetic systems of the nucleus-cytoplasm, the chloroplast, and the mitochondrion. The immutans (im) variegation mutation of Arabidopsis is nuclear and recessive and results in the production of green- and white-sectored leaves. The green sectors contain cells with normal chloroplasts, whereas the white sectors are heteroplastidic and contain cells with abnormal, pigment-deficient plastids as well as some normal chloroplasts. White sector formation can be promoted by enhanced light intensities, but sectoring becomes irreversible early in leaf development. The white sectors accumulate the carotenoid precursor phytoene. We have positionally cloned IM and found that the gene encodes a 40.5-kD protein with sequence motifs characteristic of alternative oxidase, a mitochondrial protein that functions as a terminal oxidase in the respiratory chains of all plants. However, phylogenetic analyses revealed that the IM protein is only distantly related to these other alternative oxidases, suggesting that IM is a novel member of this protein class. We sequenced three alleles of im, and all are predicted to be null. Our data suggest a model of variegation in which the IM protein functions early in chloroplast biogenesis as a component of a redox chain responsible for phytoene desaturation but that a redundant electron transfer function is capable of compensating for IM activity in some plastids and cells.

The IMMUTANS variegation locus of Arabidopsis defines a mitochondrial alternative oxidase homolog that functions during early chloroplast biogenesis

Nuclear gene-induced variegation mutants provide a powerful system to dissect interactions between the genetic systems of the nucleus-cytoplasm, the chloroplast, and the mitochondrion. The immutans (im) variegation mutation of Arabidopsis is nuclear and recessive and results in the production of green- and white-sectored leaves. The green sectors contain cells with normal chloroplasts, whereas the white sectors are heteroplastidic and contain cells with abnormal, pigment-deficient plastids as well as some normal chloroplasts. White sector formation can be promoted by enhanced light intensities, but sectoring becomes irreversible early in leaf development. The white sectors accumulate the carotenoid precursor phytoene. We have positionally cloned IM and found that the gene encodes a 40.5-kD protein with sequence motifs characteristic of alternative oxidase, a mitochondrial protein that functions as a terminal oxidase in the respiratory chains of all plants. However, phylogenetic analyses revealed that the IM protein is only distantly related to these other alternative oxidases, suggesting that IM is a novel member of this protein class. We sequenced three alleles of im, and all are predicted to be null. Our data suggest a model of variegation in which the IM protein functions early in chloroplast biogenesis as a component of a redox chain responsible for phytoene desaturation but that a redundant electron transfer function is capable of compensating for IM activity in some plastids and cells.

Insulin injection sites: morphology and immunohistochemistry

In a case of insulin suicide in a nondiabetic woman, insulin was detected in routinely formalin fixed and paraffin embedded subcutaneous injection marks, in spite of a post-morterm interval of 24 days. Around birefringent crystalline material, probably zinc phosphate, immunohistochemistry revealed granular insulin depots as well as an insulin staining along the lipocyte membranes. A cellular reaction of granulocytic character was present, with an uptake of insulin by inflammatory cells.

[Outcome of cataract operation with reduction of myopia in myopia magna]

Patients with high myopia represent a risk group in cataract surgery. They are suspected of having a higher incidence of retina problems after cataract surgery. In addition, IOL calculations may be difficult.

METHOD

In a retrospective study data of 97 eyes of 60 high myopic patients were analyzed. The inclusion criterion was an axial length of > 26 mm. All eyes underwent cataract extraction and PC IOL implantation between 1991 and 1995. Evaluation focused on visual outcome, precision of the IOL power calculation and the rate of complications.

RESULTS

Visual acuity increased from 0.18 to 0.46 postoperatively. On average, myopia was reduced from -13.6 D to -3.0 D;66% of the patients were +/-1 D;86% were +/-2 D within the predicted calculation of postoperative refraction. During a follow-up period of 14.8 months no retinal detachment occurred.

CONCLUSION

Cataract extraction and IOL implantation showed good functional results, and prediction of postoperative refraction was satisfactory. Our data support the studies reporting a low incidence of retinal problems in patients with high myopia.

[Improving contrast sensitivity by cut-off filters in high adaptation luminance levels in retinitis pigmentosa]

BACKGROUND

Contrast requirements in patients suffering from retinitis pigmentosa (RP) exceed those of healthy subjects. So far, studies examining contrast sensitivity have been performed at luminance levels of several 100 cd/m2. However, to simulate as closely as possible outdoor levels of luminance, several 1000 cd/m2 are necessary.

PATIENTS AND METHODS

We used the Vistech contrast sensitivity charts at a standard high luminance of 5500 cd/m2. Contrast sensitivity was evaluated in 20 healthy subjects (visual acuity 1.10 +/- 0.15) and 25 patients with RP (visual acuity 0.50 +/- 0.29) with and without commercially available cut-off spectacle filters (Zeiss F 80, Zeiss F 90 and Rodenstock L 660.

RESULTS

Patients with retinitis pigmentosa showed an increase of contrast sensitivity with all three cut-off filters. This was statistically significant at a spatial frequency of 1.5 cycl/deg (P < 0.027), but not for higher frequencies of 6-18 cycl/deg (P < 0.5). The healthy volunteers did not show any increase in contrast sensitivity values with cut-off filters.

CONCLUSION

Evaluating contrast sensitivity at high levels of luminance is useful to identify patients who benefit from cut-off filters. All RP patients subjectively preferred to wear cut-off filters. A statistically proven beneficial effect of cut-off glasses could be found for low spatial frequencies. An individual fitting of the various types of cut-off filters is inevitable.

[Dialectic hermeneutics: a way of thinking in nursing research]

This paper is a theoretical study about dialectic and hermeneutics union and the possibility of its application as a "way of thinking" in nursing research. For this, we retake its origin and discussion at the present time, as well as the theoretical postulates that gives it foundation, looking forward on expanding the horizons in nursing investigation.

ABH and Lewis immunohistochemistry of the human eye

ABH and Lewis antigens are detected by immunohistochemistry exclusively in the anterior cornea epithelium and in the conjunctiva bulbi, but not in the ciliary body, in the retina, or in the vitreous body of the eye. The ABH antigens found in the vitreous humor by the absorption elution technique (Rordorf et al., Forensic Sci. Int. 41, 1989, 111-116) are probably glycosphingolipids, which are not detected by immunohistochemistry. They may come from the plasma of uveal blood vessels, or be produced by local cells.

Progesterone receptor-mediated effects of neuroactive steroids

Several 3 alpha-hydroxysteroids accumulate in the brain after local synthesis or after metabolization of steroids that are provided by the adrenals. The 3 alpha-hydroxy ring A-reduced pregnane steroids allopregnanolone and tetrahydrodeoxycorticosterone are believed not to interact with intracellular receptors, but enhance GABA-mediated chloride currents. The present study shows that these neuroactive steroids can regulate gene expression via the progesterone receptor. The induction of DNA binding and transcriptional activation of the progesterone receptor requires intracellular oxidation of the neuroactive steroids into progesterone receptor active 5 alpha-pregnane steroids. Thus, at physiological concentrations, these neuroactive steroids regulate neuronal function through their effects on both transmitter-gated ion channels and steroid receptor-regulated gene expression.

[The Kontron ABT 4000 respirator. Description, working mechanism and evaluation]

The ABT 4000 ventilator is aimed at being used in operating theatres, as it can be used in an open or a closed circuit, as well as for short periods of artificial ventilation with room air with or without added oxygen. This paper gives a description of the apparatus easy to understand, as well as an analysis of the workings of this constant volume ventilator controlled by microprocessor.

Retinopathy of prematurity: the influence of gestational age and retinal maturity on the statistical behavior of risk factors

The clinical and laboratory data on 140 premature infants, 74 cases with retinopathy of prematurity (ROP) and 66 control cases without ROP, were correlated with ROP grades of increasing severity. By using multiple linear regression (MLR), it is shown that for predicting ROP grades the importance of certain variables varies considerably depending on the gestational age. Below 32 weeks of gestation, acidosis, hyperoxemia, gestational age, pathologic paCO2 levels, and multiple birth are strong regressors. Above 31 weeks, the most important regressors are multiple birth and acidosis, while gestational age and duration of FiO2 greater than 0.4 are much less influential. Blood transfusions and artificial ventilation do not seem important in the MLR of either group. When ROP is regressed on the number of paO2 values above 100 torr and gestational age or on the number of paCO2 values above 50 torr and gestational age, the regression coefficients of these variables drop to near zero at a gestational age of about 32 weeks. This loss of weight of the two variables paO2 and paCO2 with increasing gestational age coincides with a comparable drop of the relative incidence of ROP and the relative incidence of immature retinal vessels. It is hypothesized that it is the proportion of infants with an immature retinal vasculature in populations of given gestational ages rather than the gestational age itself which is responsible for the widely varying importance of certain factors during the development of ROP.

Improving physician compliance with preventive medicine guidelines

Similar general medical outpatient clinics with randomly assigned patients were used to evaluate the effectiveness of a program that was to increase house staff compliance with preventive medicine guidelines. Two clinics were designated experimental and two served as controls. In the experimental clinics, age-specific checklists of all recommended preventive procedures (drawn from the Canadian Task Force report on The Periodic Health Examination and American Cancer Society guidelines) were appended to each patient's chart. In addition, house officers were presented with a series of weekly seminars dealing with issues in screening, as well as the specific recommendations included in the checklist. House officers in all four clinics were tested for their knowledge and attitudes toward the preventive program before and after the intervention. Counts of immunizations and mammograms performed and the total populations eligible for these procedures were determined for all four clinics. As predicted, test scores as well as mammography and immunization rates increased significantly (from 2-40 per cent) in the intervention clinics as compared with controls. We conclude that this intervention was clearly effective in the short run. However, follow-up studies will be necessary to determine whether the desired long-term effect has been achieved.