Neural Mechanisms of the Acceptable Noise Level

PURPOSE

The present brain-behavior study examined whether sensory registration or neural inhibition processes explained variability in the behavioral most comfortable level (MCL) and background noise level (BNL) components of the acceptable noise level (ANL) measure.

METHOD

A traditional auditory gating paradigm was used to evoke neural responses to pairs of pure-tone stimuli in 32 adult listeners with normal hearing. Relationships between behavioral ANL, MCL, and BNL components and cortical responses to each of the paired stimuli were analyzed using linear mixed-effects regression analyses.

RESULTS

Neural responses elicited by Stimulus 2 in the gating paradigm significantly predicted the computed ANL response. The MCL component was significantly associated with responses elicited by Stimulus 1 of the pair. The BNL component of the ANL was significantly associated with neural responses to both Stimulus 1 and Stimulus 2.

CONCLUSIONS

The results suggest neural processes related to neural inhibition support the ANL and BNL component while neural stimulus registration properties are associated with the MCL a listener chooses. These findings suggest that differential neural mechanisms underlie the separate MCL and BNL components of the ANL response.

Genome-wide Gene-by-Sex Interaction Studies Identify Novel Nonsyndromic Orofacial Clefts Risk Locus

Risk loci identified through genome-wide association studies have explained about 25% of the phenotypic variations in nonsyndromic orofacial clefts (nsOFCs) on the liability scale. Despite the notable sex differences in the incidences of the different cleft types, investigation of loci for sex-specific effects has been understudied. To explore the sex-specific effects in genetic etiology of nsOFCs, we conducted a genome-wide gene × sex (GxSex) interaction study in a sub-Saharan African orofacial cleft cohort. The sample included 1,019 nonsyndromic orofacial cleft cases (814 cleft lip with or without cleft palate and 205 cleft palate only) and 2,159 controls recruited from 3 sites (Ethiopia, Ghana, and Nigeria). An additive logistic model was used to examine the joint effects of the genotype and GxSex interaction. Furthermore, we examined loci with suggestive significance (P < 1E-5) in the additive model for the effect of the GxSex interaction only. We identified a novel risk locus on chromosome 8p22 with genome-wide significant joint and GxSex interaction effects (rs2720555, p_2df = 1.16E-08, p_GxSex = 1.49E-09, odds ratio [OR] = 0.44, 95% CI = 0.34 to 0.57). For males, the risk of cleft lip with or without cleft palate at this locus decreases with additional copies of the minor allele (p < 0.0001, OR = 0.60, 95% CI = 0.48 to 0.74), but the effect is reversed for females (p = 0.0004, OR = 1.36, 95% CI = 1.15 to 1.60). We replicated the female-specific effect of this locus in an independent cohort (p = 0.037, OR = 1.30, 95% CI = 1.02 to 1.65), but no significant effect was found for the males (p = 0.29, OR = 0.86, 95% CI = 0.65 to 1.14). This locus is in topologically associating domain with craniofacially expressed and enriched genes during embryonic development. Rare coding mutations of some of these genes were identified in nsOFC cohorts through whole exome sequencing analysis. Our study is additional proof that genome-wide GxSex interaction analysis provides an opportunity for novel findings of loci and genes that contribute to the risk of nsOFCs.

Safety and efficacy of a home nasogastric monitoring program for premature infants

BACKGROUND

A novel home monitoring program, in which premature infants are cared for at home with a nasogastric tube in place prior to achievement of full oral feeding, was evaluated. The program combines a digital, fully EMR-integrated, virtual daily rounding platform with direct provider video and telephone contact.

METHODS

A case-control study was performed evaluating infants <  34 weeks' gestation who were followed in our program. A historical control group, was created by matching 2 : 1 based on gestational age±6 days, retroactively.

RESULT

15 patients discharged in the program were compared with 30 controls. The home cohort gained an average of 30 g/day compared with the in-hospital group at 27g/day (p = 0.325). The home group required a mean of 5.9±2.9 days to full oral feeding once discharged, not different from the control group at 5.4±3.7 days (p = 0.606). The percentage of oral feeds for the home cohort, however, increased at a rate of 12.2%before discharge compared to rising 57%at home (p <  0.001). The control group spent an additional 8.1±3.9 days in the hospital after reaching criteria. There were no reported adverse events or readmissions.

CONCLUSION

Premature infants can safely advance oral feeds using a home monitoring program. While at home, infants gained weight similarly to their inpatient controls inpatient, yet gained full oral skills at a significantly faster rate compared to when they were in the hospital.

Auditory Sensory Gating of Speech and Nonspeech Stimuli

Purpose Auditory sensory gating is a neural measure of inhibition and is typically measured with a click or tonal stimulus. This electrophysiological study examined if stimulus characteristics and the use of speech stimuli affected auditory sensory gating indices. Method Auditory event-related potentials were elicited using natural speech, synthetic speech, and nonspeech stimuli in a traditional auditory gating paradigm in 15 adult listeners with normal hearing. Cortical responses were recorded at 64 electrode sites, and peak amplitudes and latencies to the different stimuli were extracted. Individual data were analyzed using repeated-measures analysis of variance. Results Significant gating of P1-N1-P2 peaks was observed for all stimulus types. N1-P2 cortical responses were affected by stimulus type, with significantly less neural inhibition of the P2 response observed for natural speech compared to nonspeech and synthetic speech. Conclusions Auditory sensory gating responses can be measured using speech and nonspeech stimuli in listeners with normal hearing. The results of the study indicate the amount of gating and neural inhibition observed is affected by the spectrotemporal characteristics of the stimuli used to evoke the neural responses.

SARS-CoV-2 has not been detected directly by electron microscopy in the endothelium of chilblain lesions

Linked Article: Colmenero et al. Br J Dermatol 2020; 183:729–737.

Benefits of a Hearing Registry: Cochlear Implant Candidacy in Quiet Versus Noise in 1,611 Patients

Purpose This retrospective study used a cochlear implant registry to determine how performing speech recognition candidacy testing in quiet versus noise influenced patient selection, speech recognition, and self-report outcomes. Method Database queries identified 1,611 cochlear implant recipients who were divided into three implant candidacy qualifying groups based on preoperative speech perception scores (≤ 40% correct) on the AzBio sentence test: quiet qualifying group, +10 dB SNR qualifying group, and +5 dB SNR qualifying group. These groups were evaluated for demographic and preoperative hearing characteristics. Repeated-measures analysis of variance was used to compare pre- and postoperative performance on the AzBio in quiet and noise with qualifying group as a between-subjects factor. For a subset of recipients, pre- to postoperative changes on the Speech, Spatial and Qualities of Hearing Scale were also evaluated. Results Of the 1,611 patients identified as cochlear implant candidates, 63% of recipients qualified in quiet, 10% qualified in a +10 dB SNR, and 27% qualified in a +5 dB SNR. Postoperative speech perception scores in quiet and noise significantly improved for all qualifying groups. Across qualifying groups, the greatest speech perception improvements were observed when tested in the same qualifying listening condition. For a subset of patients, the total Speech, Spatial and Qualities of Hearing Scale ratings improved significantly as well. Conclusion Patients who qualified for cochlear implantation in quiet or background noise test conditions showed significant improvement in speech perception and quality of life scores, especially when the qualifying noise condition was used to track performance.

Insurance Payer Status Predicts Postoperative Speech Outcomes in Adult Cochlear Implant Recipients

BACKGROUND

Cochlear implant qualifying criteria for adult patients with public insurance policies are stricter than the labeled manufacturer criteria. It remains unclear whether insurance payer status affects expedient access to implants for adult patients who could derive benefit from the devices.

PURPOSE

This study examined whether insurance payer status affected access to cochlear implant services and longitudinal speech-perception outcomes in adult cochlear implant recipients.

RESEARCH DESIGN

Retrospective cross-sectional study.

STUDY SAMPLE

Sixty-eight data points were queried from the Health Insurance Portability and Accountability Act-Secure, Encrypted, Research Management and Evaluation Solution database which consists of 12,388 de-identified data points from adult and pediatric cochlear implant recipients.

DATA ANALYSIS

Linear mixed-effects models were used to determine whether insurance payer status affected expedient access to cochlear implants and whether payer status predicted longitudinal postoperative speech-perception scores in quiet and noise.

RESULTS

Results from linear mixed-effects regression models indicated that insurance payer status was a significant predictor of behavioral speech-perception scores in quiet and in background noise, with patients with public insurance experiencing poorer outcomes. In addition, extended wait time to receive a cochlear implant was predicted to significantly decrease speech-perception outcomes for patients with public insurance.

CONCLUSION

This study documented patients covered by public health insurance wait longer to receive cochlear implants and experience poorer postoperative speech-perception outcomes. These results have important clinical implications regarding the cochlear implant candidacy criteria and intervention protocols.

Neural Coding of Syllable-Final Fricatives with and without Hearing Aid Amplification

BACKGROUND

Cortical auditory event-related potentials are a potentially useful clinical tool to objectively assess speech outcomes with rehabilitative devices. Whether hearing aids reliably encode the spectrotemporal characteristics of fricative stimuli in different phonological contexts and whether these differences result in distinct neural responses with and without hearing aid amplification remain unclear.

PURPOSE

To determine whether the neural coding of the voiceless fricatives /s/ and /ʃ/ in the syllable-final context reliably differed without hearing aid amplification and whether hearing aid amplification altered neural coding of the fricative contrast.

RESEARCH DESIGN

A repeated-measures, within subject design was used to compare the neural coding of a fricative contrast with and without hearing aid amplification.

STUDY SAMPLE

Ten adult listeners with normal hearing participated in the study.

DATA COLLECTION AND ANALYSIS

Cortical auditory event-related potentials were elicited to an /ɑs/-/ɑʃ/ vowel-fricative contrast in unaided and aided listening conditions. Neural responses to the speech contrast were recorded at 64-electrode sites. Peak latencies and amplitudes of the cortical response waveforms to the fricatives were analyzed using repeated-measures analysis of variance.

RESULTS

The P2' component of the acoustic change complex significantly differed from the syllable-final fricative contrast with and without hearing aid amplification. Hearing aid amplification differentially altered the neural coding of the contrast across frontal, temporal, and parietal electrode regions.

CONCLUSIONS

Hearing aid amplification altered the neural coding of syllable-final fricatives. However, the contrast remained acoustically distinct in the aided and unaided conditions, and cortical responses to the fricative significantly differed with and without the hearing aid.

Executive functioning in low birth weight children entering kindergarten

OBJECTIVES

Poor executive functioning is associated with life-long difficulty. Identification of children at risk for executive dysfunction is important for early intervention to improve neurodevelopmental outcomes.

STUDY DESIGN

This study is designed to examine relationships between birthweight and executive functioning in US children during kindergarten. Our hypothesis was that children with higher birthweights would have better executive function scores. We evaluated data from 17506 US children from the Early Childhood Longitudinal Study-Kindergarten 2011 cohort. Birthweight and gestational age were obtained by parental survey. Executive functions were directly assessed using the number reverse test and card sort test to measure working memory and cognitive flexibility, respectively. Teacher evaluations were used for additional executive functions. Data were analyzed using SAS to run all linear and logistical regressions.

RESULTS

For every kilogram of birthweight, scores of working memory increased by 1.47 (P<0.001) and cognitive flexibility increased by 0.28 (P<0.001) independent of gender, gestational age, parental education, and family income. Low birthweight infants were 1.5 times more likely to score in the bottom 20% of children on direct assessment OR=1.49 (CI 1.21-1.85) and OR=1.55 (CI 1.26-1.91).

CONCLUSIONS

Infants born low birthweight are at increased risk of poor executive functioning. As birthweight increases executive function scores improve, even among infants born normal weight. Further evaluation of this population including interventions and progression through school is needed.

Hemorrhagic Herpes Simplex Virus Type 1 Nephritis: An Unusual Cause of Acute Allograft Dysfunction

Interstitial nephritis due to viruses is well-described after solid organ transplantation. Viruses implicated include cytomegalovirus; BK polyomavirus; Epstein-Barr virus; and, less commonly, adenovirus. We describe a rare case of hemorrhagic allograft nephritis due to herpes simplex virus type 1 at 10 days after living donor kidney transplantation. The patient had a favorable outcome with intravenous acyclovir and reduction of immunosuppression.

Efficacy of Multiple-Talker Phonetic Identification Training in Postlingually Deafened Cochlear Implant Listeners

PURPOSE

This study implemented a pretest-intervention-posttest design to examine whether multiple-talker identification training enhanced phonetic perception of the /ba/-/da/ and /wa/-/ja/ contrasts in adult listeners who were deafened postlingually and have cochlear implants (CIs).

METHOD

Nine CI recipients completed 8 hours of identification training using a custom-designed training package. Perception of speech produced by familiar talkers (talkers used during training) and unfamiliar talkers (talkers not used during training) was measured before and after training. Five additional untrained CI recipients completed identical pre- and posttests over the same time course as the trainees to control for procedural learning effects.

RESULTS

Perception of the speech contrasts produced by the familiar talkers significantly improved for the trained CI listeners, and effects of perceptual learning transferred to unfamiliar talkers. Such training-induced significant changes were not observed in the control group.

CONCLUSION

The data provide initial evidence of the efficacy of the multiple-talker identification training paradigm for CI users who were deafened postlingually. This pattern of results is consistent with enhanced phonemic categorization of the trained speech sounds.

CALM regulates clathrin-coated vesicle size and maturation by directly sensing and driving membrane curvature

The size of endocytic clathrin-coated vesicles (CCVs) is remarkably uniform, suggesting that it is optimized to achieve the appropriate levels of cargo and lipid internalization. The three most abundant proteins in mammalian endocytic CCVs are clathrin and the two cargo-selecting, clathrin adaptors, CALM and AP2. Here we demonstrate that depletion of CALM causes a substantial increase in the ratio of “open” clathrin-coated pits (CCPs) to “necked”/“closed” CCVs and a doubling of CCP/CCV diameter, whereas AP2 depletion has opposite effects. Depletion of either adaptor, however, significantly inhibits endocytosis of transferrin and epidermal growth factor. The phenotypic effects of CALM depletion can be rescued by re-expression of wild-type CALM, but not with CALM that lacks a functional N-terminal, membrane-inserting, curvature-sensing/driving amphipathic helix, the existence and properties of which are demonstrated. CALM is thus a major factor in controlling CCV size and maturation and hence in determining the rates of endocytic cargo uptake.

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CALM loss increases size and frequency of early endocytic clathrin-coated structures

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Depletion of CALM slows endocytic clathrin-coated pit maturation and endocytic rate

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CALM possesses an N-terminal, membrane-curvature-sensing/driving amphipathic helix

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Clathrin-coated pit maturation is regulated by CALM’s N-terminal amphipathic helix

Expression of a mitochondrial progesterone receptor in human spermatozoa correlates with a progestin-dependent increase in mitochondrial membrane potential

The hyperactivation of human spermatozoa necessary for fertilization requires a substantial increase in cellular energy production. The factors responsible for increasing cellular energy remain poorly defined. This article proposes a role for a novel mitochondrial progesterone receptor (PR-M) in modulation of mitochondrial activity. Basic science studies demonstrate a 38 kDa protein with western blot analysis, consistent with PR-M; whereas imaging studies with confocal and immunoelectron microscopy demonstrate a PR on the mitochondria. Treatment with a PR-specific progestin shows increased mitochondrial membrane potential, not related to induction of an acrosome reaction. The increase in mitochondrial membrane potential was inhibited by a specific PR antagonist, but not affected by an inhibitor to the progesterone-dependent Catsper voltage-activated channel. In conclusion, these studies suggest expression of a novel mitochondrial PR in human spermatozoa with a progestin-dependent increase in mitochondrial activity. This mechanism may serve to enhance cellular energy production as the spermatozoa traverse the female genital tract being exposed to increasing concentrations of progesterone.

Uncoupling the functions of CALM in VAMP sorting and clathrin-coated pit formation

CALM (clathrin assembly lymphoid myeloid leukemia protein) is a cargo-selective adaptor for the post-Golgi R-SNAREs VAMPs 2, 3, and 8, and it also regulates the size of clathrin-coated pits and vesicles at the plasma membrane. The present study has two objectives: to determine whether CALM can sort additional VAMPs, and to investigate whether VAMP sorting contributes to CALM-dependent vesicle size regulation. Using a flow cytometry-based endocytosis efficiency assay, we demonstrate that CALM is also able to sort VAMPs 4 and 7, even though they have sorting signals for other clathrin adaptors. CALM homologues are present in nearly every eukaryote, suggesting that the CALM family may have evolved as adaptors for retrieving all post-Golgi VAMPs from the plasma membrane. Using a knockdown/rescue system, we show that wild-type CALM restores normal VAMP sorting in CALM-depleted cells, but that two non-VAMP-binding mutants do not. However, when we assayed the effect of CALM depletion on coated pit morphology, using a fluorescence microscopy-based assay, we found that the two mutants were as effective as wild-type CALM. Thus, we can uncouple the sorting function of CALM from its structural role.

The molecular basis for the endocytosis of small R-SNAREs by the clathrin adaptor CALM

SNAREs provide a large part of the specificity and energy needed for membrane fusion and, to do so, must be localized to their correct membranes. Here, we show that the R-SNAREs VAMP8, VAMP3, and VAMP2, which cycle between the plasma membrane and endosomes, bind directly to the ubiquitously expressed, PtdIns4,5P(2)-binding, endocytic clathrin adaptor CALM/PICALM. X-ray crystallography shows that the N-terminal halves of their SNARE motifs bind the CALM(ANTH) domain as helices in a manner that mimics SNARE complex formation. Mutation of residues in the CALM:SNARE interface inhibits binding in vitro and prevents R-SNARE endocytosis in vivo. Thus, CALM:R-SNARE interactions ensure that R-SNAREs, required for the fusion of endocytic clathrin-coated vesicles with endosomes and also for subsequent postendosomal trafficking, are sorted into endocytic vesicles. CALM's role in directing the endocytosis of small R-SNAREs may provide insight into the association of CALM/PICALM mutations with growth retardation, cognitive defects, and Alzheimer's disease.

The effects of fundamental frequency contour manipulations on speech intelligibility in background noise

Previous studies have documented that speech with flattened or inverted fundamental frequency (F0) contours is less intelligible than speech with natural variations in F0. The purpose of this present study was to further investigate how F0 manipulations affect speech intelligibility in background noise. Speech recognition in noise was measured for sentences having the following F0 contours: unmodified, flattened at the median, natural but exaggerated, inverted, and sinusoidally frequency modulated at rates of 2.5 and 5.0 Hz, rates shown to make vowels more perceptually salient in background noise. Five talkers produced 180 stimulus sentences, with 30 unique sentences per F0 contour condition. Flattening or exaggerating the F0 contour reduced key word recognition performance by 13% relative to the naturally produced speech. Inverting or sinusoidally frequency modulating the F0 contour reduced performance by 23% relative to typically produced speech. These results support the notion that linguistically incorrect or misleading cues have a greater deleterious effect on speech understanding than linguistically neutral cues.

A structural explanation for the binding of endocytic dileucine motifs by the AP2 complex

Most transmembrane proteins are selected as transport vesicle cargo through the recognition of short, linear amino acid motifs in their cytoplasmic portions by vesicle coat proteins. In the case of clathrin-coated vesicles (CCVs) the motifs are recognised by clathrin adaptors. The AP2 adaptor complex (subunits α,β2,μ2,σ2) recognises both major endocytic motifs: YxxΦ motifs ¹ and [DE]xxxL[LI] acidic dileucine motifs. Here we describe the binding of AP2 to the endocytic dileucine motif from CD4 ². The major recognition events are the two leucine residues binding in hydrophobic pockets on σ2. The hydrophilic residue four residues upstream from the first leucine sits on a positively charged patch made from residues on σ2 and α subunits. Mutations in key residues inhibit the binding of AP2 to ‘acidic dileucine’ motifs displayed in liposomes containing PtdIns4,5P₂, but do not affect binding to YxxΦ motifs via μ2. In the ‘inactive’ AP2 core structure ³, both motif binding sites are blocked by different parts of the β2 subunit. To allow a dileucine motif to bind, the β2 N-terminus is displaced and becomes disordered; however, in this structure the YxxΦ binding site on μ2 remains blocked.

TDP-43 accumulation in inclusion body myopathy muscle suggests a common pathogenic mechanism with frontotemporal dementia

TAR DNA binding protein-43 (TDP-43) is found in ubiquitinated inclusions (UBIs) in some frontotemporal dementias (FTD-U). One form of FTD-U, due to mutations in the valosin containing protein (VCP) gene, occurs with an inclusion body myopathy (IBMPFD). Since IBMPFD brain has TDP-43 in UBIs, we looked for TDP-43 inclusions in IBMPFD muscle. In normal muscle, TDP-43 is present in nuclei. In IBMPFD muscle, TDP-43 is additionally present as large inclusions within UBIs in muscle cytoplasm. TDP-43 inclusions were also found in 78% of sporadic inclusion body myositis (sIBM) muscles. In IBMPFD and sIBM muscle, TDP-43 migrated with an additional band on immunoblot similar to that reported in FTD-U brains. This study adds sIBM and hereditary inclusion body myopathies to the growing list of TDP-43 positive inclusion diseases.

EpsinR is an adaptor for the SNARE protein Vti1b

EpsinR is a clathrin-coated vesicle (CCV)-associated protein that binds to vti1b, suggesting that it may be a vti1b-selective adaptor. Depletion of epsinR to undetectable levels in HeLa cells using siRNA causes vti1b to redistribute from the perinuclear region to the cell periphery, but vti1a also redistributes in epsinR-depleted cells, and both vti isoforms redistribute in AP-1-depleted cells. As a more direct assay for epsinR function, we isolated CCVs from control and siRNA-treated cells and then looked for differences in cargo content. In clathrin-depleted cells, both coat and cargo proteins are greatly reduced in this preparation. Knocking down epsinR causes a approximately 50% reduction in the amount of AP-1 copurifying with CCVs and vice versa, indicating that the two proteins are dependent on each other for maximum incorporation into the coat. In addition, vti1b, but not vti1a, is reduced by >70% in CCVs from both epsinR- and AP-1-depleted cells. Because AP-1 knockdown reduces the amount of epsinR in CCVs, it is possible that its effect on vti1b may be indirect. These findings provide in vivo evidence that epsinR is an adaptor for vti1b, and they also show that CCV isolation can be used as an assay for adaptor function.

Outbreaks of acute gastroenteritis associated with Norwalk-like viruses in campus settings

Norwalk-like viruses (NLVs) are transmitted by fecally contaminated food, water, fomites, and person-to-person contact. They are a leading cause of acute gastroenteritis epidemics in industrialized countries. NLV outbreaks are characterized by a 12- to 48-hour incubation period; nausea, vomiting, and diarrhea for 24 to 72 hours; and high secondary attack rates. NLV infections spread rapidly on college and university campuses because of close living quarters, shared bathrooms and common rooms, many food handlers, popular self-service salad bars in dining halls, and person-to-person contact through sports and recreational activities. The illness is generally mild and self-limited but an outbreak can strain the resources of campus health services and cause high absenteeism among both students and staff. Treatment is primarily through antiemetic medication and oral rehydration. Prevention and control of NLV outbreaks rests on promoting hand washing; enforcement of strict hygiene in all food preparation areas; and prompt, rigorous cleaning of potentially contaminated areas where someone has been ill.

Photophysics of pi-conjugated metal-organic oligomers: aryleneethynylenes that contain the (bpy)Re(CO)(3)Cl chromophore

A comprehensive study of a series of four monodisperse, metal-organic pi-conjugated oligomers of varying length is reported. The oligomers are based on the aryleneethynylene architecture, and they contain a 2,2'-bipyridine-5,5'-diyl (bpy) metal binding unit. The photophysical properties of the free oligomers and their complexes with the (L)Re(I)(CO)(3)X chromophore (where L = the bpy-oligomer and X = Cl or NCCH(3)) were explored by a variety of methods including electrochemistry, UV-visible absorption, variable temperature photoluminescence (PL), transient absorption (TA), and time-resolved electron paramagnetic spectroscopy (TREPR). The absorption of the free oligomers and the metal complexes is dominated by the pi,pi* transitions of the pi-conjugated oligomers. The free oligomers feature a strong blue fluorescence that is quenched entirely in the (L)Re(I)(CO)(3)X complexes. The metal-oligomers feature a weak, relatively long-lived red photoluminescence that is assigned to emission from both the (3)pi,pi* manifold of the pi-conjugated system and the dpi Re --> pi* bpy-oligomer metal-to-ligand charge transfer ((3)MLCT) state. On the basis of a detailed analysis of the PL, TA, and TREPR results an excited-state model is developed which indicates that the oligomer-based (3)pi,pi* state and the (3)MLCT states are in close energetic proximity. Consequently the photophysical properties reflect a composite of the properties of the two excited-state manifolds.

Comparison of teaching methods to learn a tilt and balance wheelchair skill

Often service professionals working with individuals who use wheelchairs find themselves inadequately prepared to give hands-on or verbal assistance in wheelchair maneuverability skills. The purpose of this study was to examine the effectiveness of two methods of teaching a tilt and balance wheelchair skill, evaluated by using an obstacle course. Subjects were 30 volunteers, having no past wheelchair experience. The Instruction group viewed an instructional video followed by structured wheelchair practice. The Instruction plus Biomechanics group experienced these same interventions and received a biomechanical explanation of the wheelchair skill. The Control group received no instruction but did receive additional practice time in a wheelchair. It was hypothesized that the first two groups would improve their maneuverability in the wheelchair over the Control group. A 2-way analysis of variance, with main effects for groups followed by a Tukey post hoc test, indicated that the two instruction groups had significantly better times on the obstacle course, demonstrating better maneuverability skills than the Control group. The repeated-measures portion of the analysis of variance showed the main effect for improving time from the pretest to posttest significant for all groups with the instruction groups improving times by 30 sec. over that of the Control group. The retention test was not significantly different from the posttest, and there were no significant interactions. Results indicated a need for wheelchair users to be taught maneuverability skills systematically.

Environmental modulation of alpha(v), alpha(2) and beta(1) integrin subunit expression in human oesophageal squamous cell carcinomas

Integrins are cell adhesion molecules pivotal in regulating normal cell behaviour. Ectopic expression of integrins, characteristic of transformed cells, is instrumental in differentiation, proliferation, apoptosis, angiogenesis, matrix degradation and migration. Oesophageal squamous cell carcinoma (SCC) has a propensity to metastasize and hence an extremely poor prognosis. It is shown here that oesophageal SCCs express alpha(v)strongly and that normal oesophageal tissue does not express alpha(v). This makes alpha(v)a significant indicator of the transformed phenotype. alpha(2)and beta(1)integrin subunits are down-regulated in oesophageal SCCs compared to normal oesophagus. Dominance of the alpha(2)beta(1)heterodimer is symptomatic of potential loss of other beta(1)binding integrins in oesophageal SCCs. These results suggest a decrease in rigid cell adhesion possibly increasing migratory potential, whilst simultaneously permitting the adhesion and migration of SCC cells on a large repertoire of ligands due to de novo alpha(v)expression.

Enhanced green fluorescent protein as a marker for localizing murine cytomegalovirus in acute and latent infection

A recombinant murine cytomegalovirus (mCMV) that expresses enhanced green fluorescent protein (EGFP) under control of the native immediate-early 1/3 promoter was constructed to detect directly sites of viral activity in latent and reactivated infections. The recombinant virus had acute and latent infection characteristics similar to those of wild-type mCMV. Rare green-fluorescing foci were observed in paraffin sections from lungs and spleens infected latently. Positive immunoperoxidase staining for EGFP in sections of the same lung tissues suggests that these cells may be sites of restricted viral gene expression. EGFP was detected easily in tissue explants reactivating from latent infection in vitro. Morphology and adhesion characteristics of fluorescing cells suggest that viral reactivation occurs in tissue macrophages in explant cultures. The observations presented in this study demonstrate the usefulness of EGFP-expressing recombinants as tools for direct tracking of mCMV activity in vivo and in vitro.

Direct measurement of hole transport dynamics in DNA

Our understanding of oxidative damage to double helical DNA and the design of DNA-based devices for molecular electronics is crucially dependent upon elucidation of the mechanism and dynamics of electron and hole transport in DNA. Electrons and holes can migrate from the locus of formation to trap sites, and such migration can occur through either a single-step "superexchange" mechanism or a multistep charge transport "hopping" mechanism. The rates of single-step charge separation and charge recombination processes are found to decrease rapidly with increasing transfer distances, whereas multistep hole transport processes are only weakly distance dependent. However, the dynamics of hole transport has not yet been directly determined. Here we report spectroscopic measurements of photoinduced electron transfer in synthetic DNA that yield rate constants of approximately 5 x 10(7) s(-1) and 5 x 10(6) s(-1), respectively, for the forward and return hole transport from a single guanine base to a double guanine base step across a single adenine. These rates are faster than processes leading to strand cleavage, such as the reaction of guanine cation radical with water, thus permitting holes to migrate over long distances in DNA. However, they are too slow to compete with charge recombination in contact ion pairs, a process which protects DNA from photochemical damage.

Glomerular diseases associated with hepatitis C virus infection

Renal diseases associated with hepatitis C virus (HCV) infection are a significant problem for clinicians and diagnostic pathologists. A wide variety of disorders, including a spectrum of immune-complex glomerulonephritides, has been reported in association with hepatitis and cirrhosis caused by HCV. For some of these diseases, including membranoproliferative glomerulonephritis type I and cryoglobulinemic glomerulonephritis, plausible links between HCV and the glomerular pathology have been proposed. In other cases, the role of the virus in the pathogenesis of the renal disease is less certain. This communication catalogues the renal manifestations of HCV infection, providing clinical and pathological descriptions of the most prevalent disorders. Where available, evidence implicating HCV in the causation of the disorders is also discussed.

Trichodysplasia spinulosa--a newly described folliculocentric viral infection in an immunocompromised host

This is a case report of an immunocompromised individual who presented with progressive alopecia, friable follicular spinous processes, and erythematous, indurated papules. Examination of skin biopsies using light microscopy and immunohistochemistry revealed pathologic changes of the follicular inner root sheath epithelium with dystrophic trichohyaline granules. Electron microscopy of thin sections of tissue revealed intracellular viral particles with a size and appearance consistent with those in the Papovaviridae family. Electron microscopy of negatively stained extract from a homogenized lesion also demonstrated icosahedral viruses with papovavirus morphology. We believe this is a previously unreported folliculocentric viral infection in an immunosuppressed human host and have termed this entity "trichodysplasia spinulosa".

Diagnosis and management of BK polyomavirus interstitial nephritis in renal transplant recipients

BACKGROUND

Interstitial nephritis caused by BK polyomavirus is a recognized complication of renal transplantation. A study of renal transplant recipients at Duke University Medical Center was undertaken to evaluate diagnostic modalities and assess clinical outcomes in transplant polyomavirus infections.

METHODS

Polyomavirus nephritis was identified in 6 of 240 patients who received renal transplants between January 1996 and June 1998 and an additional patient who underwent transplantation in 1995. The clinical records of these seven patients were reviewed, as were all renal biopsy and nephrectomy specimens. Electron microscopy (EM) was performed on negatively stained urine samples from 6 patients with polyomavirus infection and 23 patients with other diagnoses.

RESULTS

Patients with polyomavirus infection shared several clinical features, including ureteral obstruction (5/7 patients), lymphocele (3/7), bacterial urinary tract infection (3/7), hematuria (3/7), cytomegalovirus infection (3/7), and immunosuppression with mycophenolate mofetil (6/7). All patients experienced elevations in serum creatinine, which stabilized or decreased in four patients with altered or decreased immunosuppression. The diagnosis of polyomavirus infection was established by renal biopsy and EM of urine in five patients, by biopsy alone in one, and by EM alone in one. Sequential examinations of urine by EM were used to monitor the course of infection in six patients.

CONCLUSIONS

Interstitial nephritis due to BK polyomavirus occurred in 2.5% of patients receiving renal transplants at our center since 1996. Polyomavirus infection can cause transplant dysfunction and graft loss, but progression of the infection can frequently be abrogated with alterations in immunosuppressive therapy. Both renal biopsy and EM of urine samples are useful in the diagnosis and monitoring of polyomavirus infections.

Identification of viral infection by confocal microscopy

Confocal microscopy is a valuable adjunct to electron microscopy in the fields of diagnostic and investigative virology. Confocal imaging can be used to examine large amounts of tissue stained by a variety of methods for evidence of viral infection. Areas thus identified can then be processed for ultrastructural study, allowing a highly focused search for viral pathogens. With the possible exception of the vibrating microtome, all of the equipment and reagents necessary for the preparation of specimens for confocal scanning are available in any well-stocked histology laboratory. Although originally developed to facilitate viral diagnosis by EM, the methods described herein can be applied to the ultrastructural study of any focal pathologic process.

Electron microscopic diagnosis of human flavivirus encephalitis: use of confocal microscopy as an aid

The distinction between intracranial viral infections and inflammatory conditions requiring immunosuppression is important. Although specific laboratory reagents are readily available for some viruses, diagnosis of arbovirus infection is more difficult. Transmission electron microscopy (TEM) theoretically allows identification of viral particles independent of reagent availability, but it has limited sensitivity. We report two cases of human flavivirus encephalitis diagnosed by TEM. Laser scanning confocal microscopy (LSCM) was used in one case to survey unembedded tissue slices for focal abnormalities, from which fragments smaller than 1 mm2 were excised for epoxy embedding. This facilitated TEM identification of intracytoplasmic, budding, 35-40 nm spherical virus particles, confirmed by serology as St. Louis encephalitis. In contrast to mosquitoes and newborn mice, in which high viral loads are associated with minimal tissue responses, these biopsies showed florid angiodestructive inflammation and microgliosis, with rare virions in necrotic perivascular cells and astrocytes. To our knowledge, this represents the first ultrastructural study of St. Louis encephalitis in humans, indicating the potential value of LSCM-aided TEM.

Intermittent perfusion protects the brain during deep hypothermic circulatory arrest

BACKGROUND

Deep hypothermic circulatory arrest (DHCA) has been shown to cause impairment in recovery of cerebral blood flow (CBF) and cerebral metabolism (CMRO2) proportional to the duration of the DHCA period. This effect on CMRO2 may be a marker for brain injury, because CMRO2 recovers normally after cardiopulmonary bypass (CPB) when DHCA is not used. The aim of this study was to investigate the effects of intermittent perfusion during DHCA on the recovery of CMRO2 after CPB and to correlate these findings with electron microscopy (EM) of the cerebral microcirculatory bed.

METHODS

Fifteen neonatal piglets were placed on CPB and cooled to 18 degrees C. Each animal then underwent either: (1) 60 minute continuous CPB (control), (2) 60 minute uninterrupted DHCA (UI-DHCA), or (3) 60 minute DHCA with intermittent perfusion (1 minute every 15 minutes) (I-DHCA). All animals were then rewarmed and weaned from CPB. Measurements of CBF and CMRO2 were taken before and after CPB. A further 9 animals underwent CPB without DHCA (2 animals) or with DHCA (7 animals), under various conditions of arterial blood gas management, intermittent perfusion, and reperfusion time.

RESULTS

UI-DHCA resulted in significant impairment to recovery of CMRO2 after CPB (p < 0.05). Regardless of the blood gas strategy used, the EM after UI-DHCA revealed extensive damage characterized by perivascular intracellular and organelle edema, and vascular collapse. I-DHCA, on the other hand, produced a pattern of normal CMRO2 recovery identical to controls, and the EM was normal for both these groups.

CONCLUSIONS

Intermittent perfusion during DHCA is clinically practical and results in normal cerebral metabolic and ultrastructural recovery. Furthermore, the correlation between brain structure and CMRO2 suggests that monitoring CMRO2 during the operation may be an outstanding way to investigate new strategies for neuroprotection designed to reduce cerebral damage in children undergoing correction of congenital cardiac defects.

Using a process action team to improve patient education

To develop an effective, coordinated, and integrated process for patient education in primary care, the Department of Veterans Affairs, Western New York Healthcare System, launched a process action team. The interdisciplinary team utilized a variety of methods, including flowcharts, cause-and-effect diagrams, and variance matrices. The team developed, implemented, and analyzed a data collection plan involving chart reviews, staff interviews, and patient-staff surveys. An improvement plan was initiated in collaboration with staff. The results highlight the importance of using a data collection plan to understand the causes of problems as well as the need for staff involvement.

Cryptosporidium, enterocytozoon, and cyclospora infections in pediatric and adult patients with diarrhea in Tanzania

Cryptosporidiosis, microsporidiosis, and cyclosporiasis were studied in four groups of Tanzanian inpatients: adults with AIDS-associated diarrhea, children with chronic diarrhea (of whom 23 of 59 were positive [+] for human immunodeficiency virus [HIV]), children with acute diarrhea (of whom 15 of 55 were HIV+), and HIV control children without diarrhea. Cryptosporidium was identified in specimens from 6/86 adults, 5/59 children with chronic diarrhea (3/5, HIV+), 7/55 children with acute diarrhea (0/7, HIV+), and 0/20 control children. Among children with acute diarrhea, 7/7 with cryptosporidiosis were malnourished, compared with 10/48 without cryptosporidiosis (P < .01). Enterocytozoon was identified in specimens from 3/86 adults, 2/59 children with chronic diarrhea (1 HIV+), 0/55 children with acute diarrhea, and 4/20 control children. All four controls were underweight (P < .01). Cyclospora was identified in specimens from one adult and one child with acute diarrhea (HIV-). Thus, Cryptosporidium was the most frequent and Cyclospora the least frequent pathogen identified. Cryptosporidium and Enterocytozoon were associated with malnutrition. Asymptomatic fecal shedding of Enterocytozoon in otherwise healthy, HIV children has not been described previously.

Nursing management of patients receiving brachytherapy for early stage prostate cancer

New technologies used in the area of prostate brachytherapy have resulted in a resurgence of interest in this modality of therapy for early stage prostate cancer. Results of prostate brachytherapy have been reported to be as favorable as radical prostatectomy. Nursing care is multifaceted and necessitates a thorough understanding of brachytherapy techniques, sequelae, and radiation safety.

Special techniques in diagnostic electron microscopy

The power of electron microscopy as a diagnostic tool can be amplified considerably by the application of ancillary preparative and analytic methods. Subcellular chemistry and structure can be examined by various forms of microprobe analysis and by special staining methods, including cytochemical, immunocytochemical, and negative staining. Qualitative ultrastructural examination can be augmented by morphometric analysis. Correlative microscopic survey methods can be used as a means of targeting ultrastructural investigations. This article provides an overview of the use of these special techniques in the diagnosis and classification of tumors and other selected pathologic processes.

Expression of a copper-containing amine oxidase by human ciliary body

PURPOSE

To examine the molecular structure and ultrastructural distribution of a novel amine oxidase in human ciliary body.

METHODS

Human ciliary bodies were solubilized with a nonionic detergent. The solubilized material was subjected to affinity chromatography with 2B4.14.1, a monoclonal antibody which recognizes a family of ciliary body glycoproteins. Proteins eluted from the affinity column were further separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Peptides produced from a 2B4.14. 1-reactive protein with an approximate molecular weight of 100 kDa were analyzed by Edman degradation. The protein thus identified was further examined by Western blotting and immunoelectron microscopy with anti-peptide antisera.

RESULTS

Peptide sequences from the 100 kDa ciliary body protein were identical to the predicted protein sequence of an amine oxidase identified recently in a human placental cDNA library. The identity of the ciliary body protein was confirmed by Western blotting with rabbit antiserum generated against the predicted carboxy-terminal peptide of human placenta amine oxidase. Western blotting under nonreducing conditions and following glycosidase digestion indicated that the native enzyme is a disulfide-linked homodimer with multiple N-linked oligosaccharide side chains. By immunoelectron microscopy, the ciliary body amine oxidase was localized to the plasma membranes of inner epithelial cells.

CONCLUSIONS

Human placenta amine oxidase is present on the plasma membranes of ciliary body inner epithelial cells. This finding provides a potential explanation for amine oxidase enzyme activity detected in previous studies of anterior segment tissues. Though the functional role of human placenta amine oxidase in the eye is unclear, it may contribute to the production of H2O2 in aqueous humor.

Community respiratory viral infection in adult lung transplant recipients

STUDY OBJECTIVE

To define the epidemiology, clinical manifestations, and long-term complications of respiratory viral infections in adult lung transplant recipients.

DESIGN

Retrospective review of the records of 122 adult lung transplant recipients over a 5-year period at one institution.

RESULTS

Ten episodes of infection with respiratory syncytial virus, parainfluenza, influenza, or adenovirus were identified. All patients presented with symptoms of respiratory tract infection. Two patients died acutely and four patients subsequently had development of obliterative bronchiolitis (OB).

CONCLUSIONS

These data suggest community respiratory viral infections cause significant morbidity and mortality in lung transplant recipients. Further prospective studies are warranted to clarify the relationship between respiratory viral infection and OB and to define the optimal therapy for these viral infections.

Novel large apolipoprotein E-containing lipoproteins of density 1.006-1.060 g/ml in human cerebrospinal fluid

Although the critical role of apolipoprotein E (apoE) allelic variation in Alzheimer's disease and in the outcome of CNS injury is now recognized, the functions of apoE in the CNS remain obscure, particularly with regard to lipid metabolism. We used density gradient ultracentrifugation to identify apoE-containing lipoproteins in human CSF. CSF apoE lipoproteins, previously identified only in the 1.063-1.21 g/ml density range, were also demonstrated in the 1.006-1.060 g/ml density range. Plasma lipoproteins in this density range include low-density lipoprotein and high-density lipoprotein (HDL) subfraction 1 (HDL1). The novel CSF apoE lipoproteins are designated HDL1. No immunoreactive apolipoprotein A-I (apo A-I) or B could be identified in the CSF HDL1 fractions. Large lipoproteins 18.3 +/- 6.6 nm in diameter (mean +/- SD) in the HDL1 density range were demonstrated by electron microscopy. Following fast protein liquid chromatography of CSF at physiologic ionic strength, apoE was demonstrated in particles of average size greater than particles containing apoA-I. The largest lipoproteins separated by this technique contained apoE without apoA-I. Thus, the presence of large apoE-containing lipoproteins was confirmed without ultracentrifugation. Interconversion between the more abundant smaller apoE-HDL subfractions 2 and 3 and the novel larger apoE-HDL1 is postulated to mediate a role in cholesterol redistribution in brain.

Oligomerization of expanded-polyglutamine domain fluorescent fusion proteins in cultured mammalian cells

Six inherited neurologic diseases, including Huntington's disease, result from the expansion of a CAG domain of the disease genes to produce a domain of more than 40 glutamines in the expressed protein. The mechanism by which expansion of this polyglutamine domain causes disease is unknown. Recent studies demonstrated oligomerization of polyglutamine-domain proteins in mammalian neurons. To study oligomerization of polyglutamine proteins and to identify heterologous protein interactions, varying length polyglutamine-green fluorescent protein fusion proteins were expressed in cultured COS-7 cells. The 19- and 35-glutamine fusion proteins (non-pathologic length) distributed diffusely throughout the cytoplasm. In contrast, 56- and 80-glutamine fusion proteins (pathologic length) formed fibrillar arrays resembling those previously observed in neurons in Huntington's disease and in a transgenic mouse model. These aggregates were intranuclear and intracytoplasmic. Intracytoplasmic aggregates were surrounded by collapsed intermediate filaments. The intermediate filament protein vimentin co-immunoisolated with expanded polyglutamine fusion proteins. This cellular model will expedite investigations into oligomerization of polyglutamine proteins and their interactions with other proteins.