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1.
Nurs Res ; 2024 May 10.
Article in English | MEDLINE | ID: mdl-38773838

ABSTRACT

BACKGROUND: For years, nurse researchers have been called upon to engage with "big data" in the electronic health record (EHR) by leading studies focusing on nurse-centric patient outcomes and providing clinical analysis of potential outcome indicators. However, the current gap in nurses' data science education and training pose a significant barrier. OBJECTIVES: We aimed to evaluate the viability of conducting nurse-led, big-data research projects within a custom-designed computational lab and examine the support required by a team of researchers with little to no big-data experience. METHODS: Four nurse-led research teams developed a research question reliant on existing EHR data. Each team was given its own virtual computational lab populated with raw data. A data science education team provided instruction in coding languages-primarily structured query language and R-and data science techniques to organize and analyze the data. RESULTS: Three research teams have completed studies, resulting in one manuscript currently undergoing peer-review and two manuscripts in progress. The final team is performing data analysis. Four barriers and four facilitators to big-data projects were identified. DISCUSSION: As the data-science learning curve is steep, organizations need to help bridge the gap between what is currently taught in doctoral nursing programs and what is required of clinical nurse researchers to successfully engage in big-data methods. Additionally, clinical nurse researchers require protected research time and a data science infrastructure that supports novice efforts with education, mentorship, and computational lab resources.

2.
Geroscience ; 46(3): 2815-2825, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38349449

ABSTRACT

Normal aging is accompanied by broad loss of cognitive function in humans and rodents, including declines in cognitive flexibility. In extinction, a conditional stimulus (CS) that was previously paired with a footshock is presented alone. This procedure reliably reduces conditional freezing behavior in young adult rats. Here, we aimed to investigate how normal aging affects extinction learning. Using young (3 months) and aged (20 months) male and female Long Evans rats, we compared extinction (using 20 CS-alone presentations) to a no extinction control (equal exposure to the conditioning chamber without CS presentations) following delay fear conditioning. We found that young animals in the extinction group showed a decrease in freezing following extinction; aged animals did not. We next examined changes in neural activity using expression of the immediate early gene zif268. In young animals, extinction corresponded with decreased expression of zif268 in the basolateral amygdala and anterior retrosplenial cortex; this was not observed in aged animals. Further, aged animals showed increased zif268 expression in each region examined, suggesting that dysfunction in neural activity precedes cognitive deficits. These results demonstrate that aging impacts both extinction learning and neural activity.


Subject(s)
Conditioning, Classical , Extinction, Psychological , Humans , Rats , Animals , Male , Female , Rats, Long-Evans , Fear , Learning
3.
Front Behav Neurosci ; 18: 1327858, 2024.
Article in English | MEDLINE | ID: mdl-38304851

ABSTRACT

Introduction: In a variety of behavioral procedures animals will show selective fear responding in shock-associated contexts, but not in other contexts. However, several factors can lead to generalized fear behavior, where responding is no longer constrained to the conditioning context and will transfer to novel contexts. Methods: Here, we assessed memory generalization using an inhibitory avoidance paradigm to determine if generalized avoidance behavior engages the retrosplenial cortex (RSC). Male and female Long Evans rats received inhibitory avoidance training prior to testing in the same context or a shifted context in two distinct rooms; one room that had fluorescent lighting (Light) and one that had red LED lighting (Dark). Results: We found that animals tested in a light context maintained context-specificity; animals tested in the same context as training showed longer latencies to cross and animals tested in the shifted context showed shorter latencies to cross. However, animals tested in the dark generalized their avoidance behavior; animals tested in the same context and animals tested in the shifted context showed similarly-high latencies to cross. We next examined expression of the immediate early gene zif268 and perineuronal nets (PNNs) following testing and found that while activity in the basolateral amygdala corresponded with overall levels of avoidance behaviors, anterior RSC (aRSC) activity corresponded with learned avoidance generally, but posterior RSC (pRSC) activity seemed to correspond with generalized memory. PNN reduction in the RSC was associated with memory formation and retrieval, suggesting a role for PNNs in synaptic plasticity. Further, PNNs did not reduce in the RSC in animals who showed a generalized avoidance behavior, in line with their hypothesized role in memory consolidation. Discussion: These findings suggest that there is differential engagement of retrosplenial subregions along the rostrocaudal axis to generalization and discrimination.

4.
Biol Psychiatry Glob Open Sci ; 3(4): 756-765, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37881558

ABSTRACT

Background: Context fear memory can be reliably reduced by subsequent pairings of that context with a weaker shock. This procedure shares similarities with extinction learning: both involve extended time in the conditioning chamber following training and reduce context-elicited fear. Unlike extinction, this weak-shock exposure has been hypothesized to engage reconsolidation-like processes that weaken the original memory. Methods: We directly compared the weak-shock procedure with extinction using male and female Long Evans rats. Results: Both repeated weak-shock exposure and extinction resulted in decreased context freezing relative to animals that received context fear conditioning but no subsequent context exposure. Conditioning with the weak shock was not enough to form a persistent context-shock association on its own, suggesting that the weak-shock procedure does not create a new memory. Weak-shock exposure in a new context can still reduce freezing elicited by the training context, suggesting that it reduces responding through a different process than extinction, which does not transcend context. Finally, reduced fear behavior produced through both extinction and weak-shock exposure was mirrored by reduced zif268 expression in the basolateral amygdala. However, only the weak-shock procedure resulted in changes in lysine-48 polyubiquitin tagging in the synapse of the basolateral amygdala, suggesting that this procedure produced long-lasting changes in synaptic function within the basolateral amygdala. Conclusions: These results suggest that the weak-shock procedure does not rely on the creation of a new inhibitory memory, as in extinction, and instead may alter the original representation of the shock to reduce fear responding.

5.
Am J Orthopsychiatry ; 93(6): 461-475, 2023.
Article in English | MEDLINE | ID: mdl-37695347

ABSTRACT

According to the Indigenist ecological systems model (Fish et al., 2022; Fish & Syed, 2018), Indigenous Peoples' histories and cultures are critical to their development. However, the inclusion of Indigenous Peoples' histories and cultures in their environments is complicated by settler colonialism-a societal structure that seeks to eliminate such important contexts. The exclusion of Indigenous Peoples' histories and cultures in their environments can have adverse effects on psychological functioning (Fryberg & Townsend, 2008; Wexler, 2009). Despite this, Indigenous Peoples continue to access their histories and cultures throughout their development to survive and thrive (Vizenor, 2008). Though the Indigenist ecological systems model offers theoretical insight into the histories and cultures that contour Indigenous Peoples' environments, there are no empirical studies that examine its most basic claims. The present study addresses this gap in the literature by exploring how historical and cultural contexts intersect with the environments that affect Indigenous Peoples' development. Through a QUANT-qual embedded mixed-methods design, our analyses of Indigenous Peoples' digital story narratives (n = 73) suggest that immediate (e.g., parents, peers, school) and distant (e.g., media, government, policies) environments are the most salient to Indigenous Peoples' development. Culture figured into Indigenous Peoples' immediate environments to a moderate extent and distant environments to a prominent extent. History did too, but to a lesser extent. We discuss the implications of these findings for Indigenous well-being and recommendations for creating a more equitable developmental landscape via partnerships with Indigenous Peoples. (PsycInfo Database Record (c) 2023 APA, all rights reserved).


Subject(s)
Indigenous Peoples , Animals , Humans , Surveys and Questionnaires
6.
Open Forum Infect Dis ; 9(2): ofab640, 2022 Feb.
Article in English | MEDLINE | ID: mdl-35106317

ABSTRACT

BACKGROUND: There is mounting evidence for the presence of postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC), but there is limited information on the spectrum, magnitude, duration, and patterns of these sequelae as well as their influence on quality of life. METHODS: We assembled a cohort of adults with a documented history of SARS-CoV-2 RNA positivity at ≥2 weeks past onset of coronavirus disease 2019 (COVID-19) symptoms or, if asymptomatic, first positive test. At 4-month intervals, we queried physical and mental health symptoms and quality of life. RESULTS: Of the first 179 participants enrolled, 10 were asymptomatic during the acute phase of SARS-CoV-2 infection, 125 were symptomatic but not hospitalized, and 44 were symptomatic and hospitalized. During the postacute phase, fatigue, shortness of breath, concentration problems, headaches, trouble sleeping, and anosmia/dysgeusia were most common through 8 months of observation. Symptoms were typically at least somewhat bothersome and sometimes exhibited a waxing-and-waning course. Some participants experienced symptoms of depression, anxiety, and post-traumatic stress, as well as difficulties with performance of usual activities. The median visual analogue scale rating of general health was lower at 4 and 8 months compared with pre-COVID-19. Two clusters of symptom domains were identified. CONCLUSIONS: Many participants report bothersome symptoms following onset of COVID-19 with variable patterns of persistence and impact on quality of life. The substantial variability suggests the existence of multiple subphenotypes of PASC. A rigorous approach to the prospective measurement of symptoms and functional manifestations sets the stage for the next phase of research focusing on the pathophysiologic causes of the various subgroups of PASC.

7.
Arthroplast Today ; 11: 178-186, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34646924

ABSTRACT

BACKGROUND: In an effort to optimize clinical outcomes and enhance stability, ultracongruent bearings have been increasingly used in primary total knee arthroplasty (TKA). The importance of the posterior cruciate ligament (PCL) and optimal sagittal tibial baseplate position in ultracongruent bearing TKA remains unknown. This study sought to determine whether these modifiable, surgical-technique-dependent variables meaningfully impact patient-reported outcome measures. METHODS: A total of 759 primary TKAs of the same dual-pivot design performed using a consistent surgical technique between January 2016 and April 2019 were retrospectively reviewed. PCL status was recorded, and anteroposterior (AP) tibial baseplate position and posterior tibial slope were measured by two independent blinded raters. Patient-reported outcomes related to pain, function, satisfaction, and activity level were analyzed in relationship to PCL status, posterior tibial slope, and AP tibial baseplate position, in addition to other pertinent covariates. RESULTS: Median age and body mass index of the cohort were 68.3 years and 33.4 kg/m2, respectively, with 73% being female. In multivariate analysis, partial or full release of the PCL was predictive of a knee "always" feeling normal (odds ratio 1.42, P = .041). Furthermore, tibial baseplate position closer to the middle of the tibia was associated with greater improvements in pain with level walking, pain while climbing stairs, and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement total scores (P ≤ .079). CONCLUSION: In congruent dual-pivot bearing TKA, partially or fully releasing the PCL and AP tibial baseplate position closer to the middle of the tibia may provide greater improvement in pain and function scores at minimum 1-year follow-up.

8.
medRxiv ; 2021 Mar 12.
Article in English | MEDLINE | ID: mdl-33758895

ABSTRACT

BACKGROUND: As the coronavirus disease 2019 (COVID-19) pandemic continues and millions remain vulnerable to infection with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), attention has turned to characterizing post-acute sequelae of SARS-CoV-2 infection (PASC). METHODS: From April 21 to December 31, 2020, we assembled a cohort of consecutive volunteers who a) had documented history of SARS-CoV-2 RNA-positivity; b) were ≥ 2 weeks past onset of COVID-19 symptoms or, if asymptomatic, first test for SARS-CoV-2; and c) were able to travel to our site in San Francisco. Participants learned about the study by being identified on medical center-based registries and being notified or by responding to advertisements. At 4-month intervals, we asked participants about physical symptoms that were new or worse compared to the period prior to COVID-19, mental health symptoms and quality of life. We described 4 time periods: 1) acute illness (0-3 weeks), 2) early recovery (3-10 weeks), 3) late recovery 1 (12-20 weeks), and 4) late recovery 2 (28-36 weeks). Blood and oral specimens were collected at each visit. RESULTS: We have, to date, enrolled 179 adults. During acute SARS-CoV-2 infection, 10 had been asymptomatic, 125 symptomatic but not hospitalized, and 44 symptomatic and hospitalized. In the acute phase, the most common symptoms were fatigue, fever, myalgia, cough and anosmia/dysgeusia. During the post-acute phase, fatigue, shortness of breath, concentration problems, headaches, trouble sleeping and anosmia/dysgeusia were the most commonly reported symptoms, but a variety of others were endorsed by at least some participants. Some experienced symptoms of depression, anxiety, and post-traumatic stress, as well as difficulties with ambulation and performance of usual activities. The median visual analogue scale value rating of general health was lower at 4 and 8 months (80, interquartile range [IQR]: 70-90; and 80, IQR 75-90) compared to prior to COVID-19 (85; IQR 75-90). Biospecimens were collected at nearly 600 participant-visits. CONCLUSION: Among a cohort of participants enrolled in the post-acute phase of SARS-CoV-2 infection, we found many with persistent physical symptoms through 8 months following onset of COVID-19 with an impact on self-rated overall health. The presence of participants with and without symptoms and ample biological specimens will facilitate study of PASC pathogenesis. Similar evaluations in a population-representative sample will be needed to estimate the population-level prevalence of PASC.

9.
Preprint in English | medRxiv | ID: ppmedrxiv-21252311

ABSTRACT

BACKGROUNDAs the coronavirus disease 2019 (COVID-19) pandemic continues and millions remain vulnerable to infection with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), attention has turned to characterizing post-acute sequelae of SARS-CoV-2 infection (PASC). METHODSFrom April 21 to December 31, 2020, we assembled a cohort of consecutive volunteers who a) had documented history of SARS-CoV-2 RNA-positivity; b) were [≥] 2 weeks past onset of COVID-19 symptoms or, if asymptomatic, first test for SARS-CoV-2; and c) were able to travel to our site in San Francisco. Participants learned about the study by being identified on medical center-based registries and being notified or by responding to advertisements. At 4-month intervals, we asked participants about physical symptoms that were new or worse compared to the period prior to COVID-19, mental health symptoms and quality of life. We described 4 time periods: 1) acute illness (0-3 weeks), 2) early recovery (3-10 weeks), 3) late recovery 1 (12-20 weeks), and 4) late recovery 2 (28-36 weeks). Blood and oral specimens were collected at each visit. RESULTSWe have, to date, enrolled 179 adults. During acute SARS-CoV-2 infection, 10 had been asymptomatic, 125 symptomatic but not hospitalized, and 44 symptomatic and hospitalized. In the acute phase, the most common symptoms were fatigue, fever, myalgia, cough and anosmia/dysgeusia. During the post-acute phase, fatigue, shortness of breath, concentration problems, headaches, trouble sleeping and anosmia/dysgeusia were the most commonly reported symptoms, but a variety of others were endorsed by at least some participants. Some experienced symptoms of depression, anxiety, and post-traumatic stress, as well as difficulties with ambulation and performance of usual activities. The median visual analogue scale value rating of general health was lower at 4 and 8 months (80, interquartile range [IQR]: 70-90; and 80, IQR 75-90) compared to prior to COVID-19 (85; IQR 75-90). Biospecimens were collected at nearly 600 participant-visits. CONCLUSIONAmong a cohort of participants enrolled in the post-acute phase of SARS-CoV-2 infection, we found many with persistent physical symptoms through 8 months following onset of COVID-19 with an impact on self-rated overall health. The presence of participants with and without symptoms and ample biological specimens will facilitate study of PASC pathogenesis. Similar evaluations in a population-representative sample will be needed to estimate the population-level prevalence of PASC.

10.
J Pediatr Surg ; 55(11): 2379-2386, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32753275

ABSTRACT

BACKGROUND: Children with acute appendicitis have historically received intravenous antibiotics before and after appendectomy, yet recent literature supports minimizing postoperative antibiotics. In this study, we examined the impact of a standardized protocol that eliminates postoperative antibiotics for nonperforated appendicitis and discontinues antibiotics at discharge for perforated appendicitis. METHODS: A retrospective review of all pediatric patients who underwent laparoscopic appendectomy for acute appendicitis between May 2013 and March 2017 was performed. Preprotocol patients (5/1/2013-3/31/2015) were compared to postprotocol patients (5/1/2015-3/31/2017), excluding those who underwent surgery during the month of protocol introduction (4/2015). Primary outcomes were postoperative antibiotic doses for nonperforated cases and antibiotics after discharge for perforated cases. Mann-Whitney and Fisher's exact tests were performed. RESULTS: Laparoscopic appendectomy was performed in 748 children before (PRE) and in 814 children after (POST) protocol implementation. Perforation rates were similar (POST 21.5 vs. PRE 21.8%, p=0.90). For nonperforated appendicitis, postoperative antibiotics were reduced (median 0 [IQR 0-0] vs. 3 [0-5] doses, p<0.001), and more patients were discharged less than 24 h after surgery (65.7 vs. 40.9%, p<0.001). Fewer patients with perforated appendicitis underwent PICC placement (8.6 vs. 21.0%, p=0.002), and fewer patients were prescribed antibiotics on discharge (33.7 vs. 89.0%, p<0.001). There were no differences between groups for complication, readmission, or return to ED rates. CONCLUSION: For children with acute appendicitis, a standardized protocol can safely reduce unnecessary antibiotics and decrease length of stay. Furthermore, the judicious use of antibiotics does not increase SSI, readmission, or overall complication rates. LEVEL OF EVIDENCE: III.


Subject(s)
Anti-Bacterial Agents/administration & dosage , Appendectomy , Appendicitis , Clinical Protocols , Inappropriate Prescribing/prevention & control , Appendicitis/drug therapy , Appendicitis/surgery , Child , Evidence-Based Medicine , Humans , Infusions, Intravenous , Retrospective Studies , Treatment Outcome
11.
Pediatr Crit Care Med ; 21(2): 113-121, 2020 02.
Article in English | MEDLINE | ID: mdl-32032262

ABSTRACT

OBJECTIVES: A method to identify pediatric sepsis episodes that is not affected by changing diagnosis and claims-based coding practices does not exist. We derived and validated a surveillance algorithm to identify pediatric sepsis using routine clinical data and applied the algorithm to study longitudinal trends in sepsis epidemiology. DESIGN: Retrospective observational study. SETTING: Single academic children's hospital. PATIENTS: All emergency and hospital encounters from January 2011 to January 2019, excluding neonatal ICU and cardiac center. EXPOSURE: Sepsis episodes identified by a surveillance algorithm using clinical data to identify infection and concurrent organ dysfunction. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A surveillance algorithm was derived and validated in separate cohorts with suspected sepsis after clinician-adjudication of final sepsis diagnosis. We then applied the surveillance algorithm to determine longitudinal trends in incidence and mortality of pediatric sepsis over 8 years. Among 93,987 hospital encounters and 1,065 episodes of suspected sepsis in the derivation period, the surveillance algorithm yielded sensitivity 78% (95% CI, 72-84%), specificity 76% (95% CI, 74-79%), positive predictive value 41% (95% CI, 36-46%), and negative predictive value 94% (95% CI, 92-96%). In the validation period, the surveillance algorithm yielded sensitivity 84% (95% CI, 77-92%), specificity of 65% (95% CI, 59-70%), positive predictive value 43% (95% CI, 35-50%), and negative predictive value 93% (95% CI, 90-97%). Notably, most "false-positives" were deemed clinically relevant sepsis cases after manual review. The hospital-wide incidence of sepsis was 0.69% (95% CI, 0.67-0.71%), and the inpatient incidence was 2.8% (95% CI, 2.7-2.9%). Risk-adjusted sepsis incidence, without bias from changing diagnosis or coding practices, increased over time (adjusted incidence rate ratio per year 1.07; 95% CI, 1.06-1.08; p < 0.001). Mortality was 6.7% and did not change over time (adjusted odds ratio per year 0.98; 95% CI, 0.93-1.03; p = 0.38). CONCLUSIONS: An algorithm using routine clinical data provided an objective, efficient, and reliable method for pediatric sepsis surveillance. An increased sepsis incidence and stable mortality, free from influence of changes in diagnosis or billing practices, were evident.


Subject(s)
Algorithms , Electronic Health Records , Epidemiological Monitoring , Sepsis/epidemiology , Adolescent , Child , Child, Preschool , Female , Hospital Mortality , Hospitals, Pediatric , Humans , Incidence , Infant , Intensive Care Units, Pediatric , Male , Retrospective Studies , Sepsis/mortality
13.
J Acoust Soc Am ; 106(6): 3637-48, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10615702

ABSTRACT

A method for computing the speech transmission index (STI) using real speech stimuli is presented and evaluated. The method reduces the effects of some of the artifacts that can be encountered when speech waveforms are used as probe stimuli. Speech-based STIs are computed for conversational and clearly articulated speech in several noisy, reverberant, and noisy-reverberant environments and compared with speech intelligibility scores. The results indicate that, for each speaking style, the speech-based STI values are monotonically related to intelligibility scores for the degraded speech conditions tested. Therefore, the STI can be computed using speech probe waveforms and the values of the resulting indices are as good predictors of intelligibility scores as those derived from MTFs by theoretical methods.


Subject(s)
Electronic Data Processing/methods , Speech Perception/physiology , Humans , Models, Theoretical , Noise
14.
J Clin Gastroenterol ; 18(3): 213-7, 1994 Apr.
Article in English | MEDLINE | ID: mdl-8034917

ABSTRACT

In 1985, a 19-year-old woman had clinical features suggesting anorectal Crohn's disease. Two years later, swelling of the vulva associated with perianal swelling developed. The clinical manifestations responded to oral prednisone until 1989, when she returned with a swelling of the upper lip, a polypoid lesion of the oral buccal mucosa, and swelling of the anus and vulva. The lip biopsy demonstrated granulomas. The illness failed to respond to systemic immunosuppressive therapy, wider consultation was made, and the diagnosis of the Melkersson-Rosenthal syndrome was made. Such an appearance of this rare condition is unusual. We describe her case and discuss the literature, raising the possibility that the Melkersson-Rosenthal syndrome and Crohn's disease are the same condition with different initial clinical appearances.


Subject(s)
Crohn Disease/diagnosis , Melkersson-Rosenthal Syndrome/diagnosis , Adult , Anal Canal/pathology , Crohn Disease/complications , Crohn Disease/pathology , Diagnosis, Differential , Female , Humans , Lip/pathology , Melkersson-Rosenthal Syndrome/complications , Melkersson-Rosenthal Syndrome/pathology , Mouth Mucosa/pathology , Rectum/pathology , Vulva/pathology
15.
J Acoust Soc Am ; 95(3): 1581-92, 1994 Mar.
Article in English | MEDLINE | ID: mdl-8176061

ABSTRACT

The effect of articulating clearly on speech intelligibility is analyzed for ten normal-hearing and two hearing-impaired listeners in noisy, reverberant, and combined environments. Clear speech is more intelligible than conversational speech for each listener in every environment. The difference in intelligibility due to speaking style increases as noise and/or reverberation increase. The average difference in intelligibility is 20 percentage points for the normal-hearing listeners and 26 percentage points for the hearing-impaired listeners. Two predictors of intelligibility are used to quantify the environmental degradations: The articulation index (AI) and the speech transmission index (STI). Both are shown to predict, reliably, performance levels within a speaking style for normal-hearing listeners. The AI is unable to represent the reduction in intelligibility scores due to reverberation for the hearing-impaired listeners. Neither predictor can account for the difference in intelligibility due to speaking style.


Subject(s)
Hearing Loss, Sensorineural/psychology , Noise , Perceptual Masking , Speech Intelligibility , Speech Perception , Adult , Female , Hearing Loss, Sensorineural/diagnosis , Humans , Male , Middle Aged , Perceptual Distortion , Psychoacoustics , Reference Values , Speech Acoustics
16.
J Acoust Soc Am ; 83(1): 145-62, 1988 Jan.
Article in English | MEDLINE | ID: mdl-3343436

ABSTRACT

A model of peripheral auditory processing that incorporates processing steps describing the conversion from the acoustic pressure-wave signal at the eardrum to the time course activity in auditory neurons has been developed. It can process arbitrary time domain waveforms and yield the probability of neural firing. The model consists of a concatenation of modules, one for each anatomical section of the periphery. All modules are based on published algorithms and current experimental data, except that the basilar membrane is assumed to be linear. The responses of this model to vowels alone and vowels in noise are compared to neural population responses, as determined by the temporal and average rate response measures of Sachs and Young [J. Acoust. Soc. Am. 66, 470-479, (1979)] and Young and Sachs [J. Acoust. Soc. Am. 66, 1381-1403, (1979)]. Despite the exclusion of nonlinear membrane mechanics, the model accurately predicts the vowel formant representations in the average localized synchronized rate (ALSR) responses and the saturating characteristics of the normalized average rate responses in quiet. When vowels are presented in background noise, the modeled ALSR responses are less robust than the neural data.


Subject(s)
Models, Biological , Speech Perception/physiology , Vestibulocochlear Nerve/physiology , Basilar Membrane/physiology , Ear, Middle/physiology , Hair Cells, Auditory/physiology , Humans , Mathematics , Synapses/physiology , Tympanic Membrane/physiology
17.
Gastroenterology ; 83(6): 1264-70, 1982 Dec.
Article in English | MEDLINE | ID: mdl-6813186

ABSTRACT

The intestinal absorption of an oral dose of zinc chloride was determined from the ratio of 65Zn and a nonabsorbed radioactive marker, 51Cr, present in a single stool specimen or the body 24-72 h later. Chromic chloride had no effect on [65Zn]zinc chloride absorption and 51Cr and 65Zn had similar intestinal transit times. In 17 healthy control subjects given 92 mumol ZnCl2 labeled with 0.5 microCi 65Zn, 52 +/- 14% (SD) of the dose was taken up from the lumen. Intestinal absorption of 65Zn at 24 h correlated closely with 65Zn body retention of zinc measured by whole-body counting 7 days later, r = 0.995. Neither zinc absorption nor zinc retention correlated with blood leukocyte zinc levels. An average of 55% of 65Zn was retained in the body from doses of 18-90 mumol ZnCl2 but a progressively smaller proportion of zinc was absorbed from doses of 180-900 mumol. The average absorption and body retention of 65Zn were significantly reduced in 7 patients with mucosal disease of the proximal intestine but they were not affected by resection of the lower jejunum, ileum, and colon. Thus the absorption of ZnCl2 from a 92-mumol dose predominantly takes place by a rate-limited mechanism in the duodenum and upper jejunum.


Subject(s)
Feces/analysis , Intestinal Absorption , Zinc/metabolism , Adolescent , Adult , Humans , Intestines/surgery , Iron/metabolism , Leukocytes/metabolism , Malabsorption Syndromes/metabolism , Middle Aged , Whole-Body Counting , Zinc Radioisotopes
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