Sensory event-related potential morphology predicts age in premature infants

OBJECTIVE

We investigated whether sensory-evoked cortical potentials could be used to estimate the age of an infant. Such a model could be used to identify infants who deviate from normal neurodevelopment.

METHODS

Infants aged between 28- and 40-weeks post-menstrual age (PMA) (166 recording sessions in 96 infants) received trains of visual and tactile stimuli. Neurodynamic response functions for each stimulus were derived using principal component analysis and a machine learning model trained and validated to predict infant age.

RESULTS

PMA could be predicted accurately from the magnitude of the evoked responses (training set mean absolute error and 95% confidence intervals: 1.41 [1.14; 1.74] weeks,p = 0.0001; test set mean absolute error: 1.55 [1.21; 1.95] weeks,p = 0.0002). Moreover, we show that their predicted age (their brain age) is correlated with a measure known to relate to maturity of the nervous system and is linked to long-term neurodevelopment.

CONCLUSIONS

Sensory-evoked potentials are predictive of age in premature infants and brain age deviations are related to biologically and clinically meaningful individual differences in nervous system maturation.

SIGNIFICANCE

This model could be used to detect abnormal development of infants' response to sensory stimuli in their environment and may be predictive of neurodevelopmental outcome.

Predictive and diagnostic measures for kernicterus spectrum disorder: a prospective cohort study

BACKGROUND

Kernicterus spectrum disorder (KSD) resulting from neonatal hyperbilirubinemia remains a common cause of cerebral palsy worldwide. This 12-month prospective cohort study followed neonates with hyperbilirubinemia to determine which clinical measures best predict KSD.

METHODS

The study enrolled neonates ≥35 weeks gestation with total serum bilirubin (TSB) ≥ 20 mg/dl admitted to Aminu Kano Hospital, Nigeria. Clinical measures included brain MRI, TSB, modified bilirubin-induced neurologic dysfunction (BIND-M), Barry-Albright Dystonia scale (BAD), auditory brainstem response (ABR), and the modified KSD toolkit. MRI signal alteration of the globus pallidus was scored using the Hyperbilirubinemia Imaging Rating Tool (HIRT).

RESULTS

Of 25 neonates enrolled, 13/25 completed 12-month follow-up and six developed KSD. Neonatal BIND-M ≥ 3 was 100% sensitive and 83% specific for KSD. Neonatal ABR was 83% specific and sensitive for KSD. Neonatal HIRT score of 2 was 67% sensitive and 75% specific for KSD; this increased to 100% specificity and sensitivity at 12 months. BAD ≥ 2 was 100% specific for KSD at 3-12 months, with 50-100% sensitivity.

CONCLUSIONS

Neonatal MRIs do not reliably predict KSD. BIND-M is an excellent screening tool for KSD, while the BAD or HIRT score at 3 or 12 months can confirm KSD, allowing for early diagnosis and intervention.

IMPACT

The first prospective study of children with acute bilirubin encephalopathy evaluating brain MRI findings over the first year of life. Neonatal MRI is not a reliable predictor of kernicterus spectrum disorders (KSD). Brain MRI at 3 or 12 months can confirm KSD. The modified BIND scale obtained at admission for neonatal hyperbilirubinemia is a valuable screening tool to assess risk for developing KSD. The Barry Albright Dystonia scale and brain MRI can be used to establish a diagnosis of KSD in at-risk infants as early as 3 months.

The effect of acute respiratory events and respiratory stimulants on EEG-recorded brain activity in neonates: A systematic review

Objective

We conducted a systematic review to investigate electroencephalography (EEG) changes during periods of acute respiratory events such as apnoea and the effect of respiratory stimulants on EEG features in infants.

Methods

Studies examining respiration and EEG-recorded brain activity in human neonates between 28 and 42 weeks postmenstrual age were included. Two reviewers independently screened all records and included studies were assessed using the Joanna Briggs Institute Critical Appraisal Tool. The protocol was registered in PROSPERO (CRD42022339873).

Results

We identified 14 studies with a total of 534 infants. Nine articles assessed EEG changes in relation to apnoea, one assessed hiccups, and four investigated the effect of respiratory stimulants. The relationship between neonatal apnoea and EEG changes was inconsistent; EEG suppression and decreased amplitude and frequency were observed during some, but not all, apnoeas. Respiratory stimulants increased EEG continuity compared with before use.

Conclusions

Current studies in this area are constrained by small sample sizes. Diverse exposure definitions and outcome measures impact inference.

Significance

This review highlights the need for further work; understanding the relationship between respiration and the developing brain is key to mitigating the long-term effects of apnoea.

Improvised bubble continuous positive airway pressure ventilation use in neonates in resource-limited settings: a systematic review and meta-analysis

OBJECTIVES

In the face of limited fiscal and technical resources, improvised methods have been used to provide effective and sustainable ventilatory support in low-resource settings to reduce neonatal mortality associated with respiratory complications. This study assessed the use of improvised bubble continuous positive airway pressure (ibCPAP) ventilation among neonates with respiratory complications and determined its effect on neonatal outcomes in low- and middle-income countries (LMICs).

CONTENT

Hospital-based studies conducted between 2010 and 2020 in LMICs were reviewed. Rayyan® software for systematic review was used for screening and article selection. We used Stata® Statacorp Texas USA software to estimate pooled prevalence, proportion estimates, weighted mean differences and 95% Confidence Interval (CI), using the random effects model.

SUMMARY

A total of 193 articles were generated and 125 were reviewed. Thirteen articles with 806 neonates on ibCPAP ventilation were included. The pooled prevalence of ibCPAP use was 7.0% (95% CI: 3.0%-13.0%). There was a significant difference in mean oxygen saturation before and after ibCPAP use (-1.34% [95% CI: -1.65% to -1.02%, p<0.01). The duration of oxygen requirement among neonates on ibCPAP was 6.5 hours less than controls (0.27 days [95%CI: -0.49 to -0.05, p<0.01).

OUTLOOK

IbCPAP had no effect on the respiratory rate, duration of admission, mortality and survival. IbCPAP use in LMIC hospitals is low and its use improved oxygen saturation and duration on oxygen among the neonates, but had no impact on length of stay, respiratory rate, mortality or survival.

Global Prevalence of Severe Neonatal Jaundice among Hospital Admissions: A Systematic Review and Meta-Analysis

Evidence regarding the adverse burden of severe neonatal jaundice (SNJ) in hospitalized neonates in resource-constrained settings is sparse. We attempted to determine the prevalence of SNJ, described using clinical outcome markers, in all World Health Organization (WHO) regions in the world. Data were sourced from Ovid Medline, Ovid Embase, Cochrane Library, African Journals Online, and Global Index Medicus. Hospital-based studies, including the total number of neonatal admissions with at least one clinical outcome marker of SNJ, defined as acute bilirubin encephalopathy (ABE), exchange blood transfusions (EBT), jaundice-related death, or abnormal brainstem audio-evoked response (aBAER), were independently reviewed for inclusion in this meta-analysis. Of 84 articles, 64 (76.19%) were from low- and lower-middle-income countries (LMICs), and 14.26% of the represented neonates with jaundice in these studies had SNJ. The prevelance of SNJ among all admitted neonates varied across WHO regions, ranging from 0.73 to 3.34%. Among all neonatal admissions, SNJ clinical outcome markers for EBT ranged from 0.74 to 3.81%, with the highest percentage observed in the African and South-East Asian regions; ABE ranged from 0.16 to 2.75%, with the highest percentages observed in the African and Eastern Mediterranean regions; and jaundice-related deaths ranged from 0 to 1.49%, with the highest percentage observed in the African and Eastern Mediterranean regions. Among the cohort of neonates with jaundice, the prevalence of SNJ ranged from 8.31 to 31.49%, with the highest percentage observed in the African region; EBT ranged from 9.76 to 28.97%, with the highest percentages reported for the African region; ABE was highest in the Eastern Mediterranean (22.73%) and African regions (14.51%). Jaundice-related deaths were 13.02%, 7.52%, 2.01% and 0.07%, respectively, in the Eastern Mediterranean, African, South-East Asian and European regions, with none reported in the Americas. aBAER numbers were too small, and the Western Pacific region was represented by only one study, limiting the ability to make regional comparisons. The global burden of SNJ in hospitalized neonates remains high, causing substantial, preventable morbidity and mortality especially in LMICs.

Eclampsia a preventable tragedy: an African overview

Eclampsia is a multisystemic disease associated with various complications which individually or in combination can lead to maternal/fetal morbidity and mortality. Developed countries and some developing countries were largely successful in reducing the incidence of eclampsia. Developing countries especially those in Sub-Saharan Africa (SSA) are still dealing with high incidence of eclampsia. The question is why have the incidence and mortality of eclampsia remained high in SSA? The risk factors for this disease are globally the same but a critical assessment showed that there are certain risk factors that are common in Sub-Saharan Africa (multiple pregnancy, sickle cell disease, pregnancies at the extremes of reproductive age, pre-existing vasculitis). In addition, there are compounding factors (illiteracy, poverty, superstitious beliefs, poor prenatal care services, poorly trained manpower and lack of facilities to cater for patients). Addressing the menace of this disease require a holistic approach which among others, includes education to address beliefs and reduce harmful practices, poverty alleviation which will improve the ability for communities to afford health care services. Improving transport services to convey patients quickly to facilities on time when there is need. Improving the health infrastructure, building more facilities, providing trained and motivated manpower and regular supply of quality essential drugs for the management of the disease. This review is meant to analyze factors prevalent in Sub-Saharan that hinder reducing incidence of the disease and provide comprehensive and cost-effective solutions.

Impediments to maternal mortality reduction in Africa: a systemic and socioeconomic overview

Maternal mortality is nowadays more of a problem of developing countries especially those in Sub-Saharan Africa (SSA). Maternal mortality has to large extent been eliminated in developed countries and has drastically been reduced in many other regions of the world. The maternal mortality rate (MMR) available in the literature from Africa is not a true reflection of the actual MMR as it is derived from institutional studies. The causes of maternal mortality in SSA are the same as those in developed countries. The means of addressing maternal mortality used in developed countries are the same as those used in developing countries, however, the success levels are not the same. There are various impediments to reducing maternal mortality with roots in cultural, social, economic and systemic factors prevalent in SSA. An in-depth study of these factors will give an insight as to why maternal mortality reduction has remained an enigma in SSA. Analyzing these factors will guide us to design and implement measures that will in the long run lead to significant maternal mortality reduction in SSA. The aim of this review is to identify impediments to maternal mortality reduction in SSA and highlight measures that can lead to maternal mortality reduction.

Patient-reported outcomes in a linguistically diverse cancer population: Addressing barriers to access

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Background: The census metropolitan area served by BC Cancer is Vancouver which has a population of 2.4 million. Census Canada noted the mother tongue learned in childhood and still spoken was: 54% English, 17% Indo-European, 16% Chinese, 10% Indo-Iranian, 3% English+other language, 2% other. At BC Cancer, implementation of patient reported outcomes (PROs) was launched 1 year ago with consideration of preferred language. Our goal was to examine the implementation of PROs with respect to equity of access and language preferences. Methods: BC Cancer Vancouver implemented PROs including the Edmonton Symptom Assessment Scale Revised, Canadian Problem Checklist and EQ5D in April 2021 using a web-based platform. A 1-year cohort was reviewed for patients’ mother tongue and the language used for the PROs. Qualitative interviews were undertaken for non-English mother tongue patients to ask for preferred language of PROs and reasons for the choice if mother tongue was not selected. Results: 86 patients were enrolled in the PRO program. Baseline characteristics: 66% female, age 30% < 60/ 31% 60-69/ 39% >70, primary site 54% lung/ 34% colorectal/ 18% other. Ethnic origin: 53% North American and European, 40% East and Southeast Asian, 2% Latin/Central and South American, 3% South Asian, 1% Indigenous, 1% other. Mother tongue: 52% English, 48% non-English (39% English proficient, 9% low English proficiency). Patient preferred language for PROs: 81% English, 11% Chinese, 7% other. Reasons for non-English mother tongue preference for English language included comfort with written English, use of family assistance completing questionnaires for both language and familiarity with electronic devices. Conclusions: In the Vancouver linguistically diverse cancer population, the majority of patients preferred English language PROs. Reasons for this include proficiency in the written language and the use of family members to complete the questionnaires. With 39% of patients over the age of 70 in our study, the use of electronic devices for completion may have introduced an additional barrier to access. In clinic iPad questionnaires with nursing and care aide support have been introduced to help address this gap. Clinical trial information: NCT05057234.

Perinatal factors associated with admission to neonatal intensive care unit following cesarean delivery in Kano, northern Nigeria

OBJECTIVES

Cesarean section is the most common obstetric surgical procedure, with associated risks for adverse neonatal outcomes. The interplay of perinatal factors associated with neonatal admissions following cesarean delivery remains poorly understood in developing countries. We examined how perinatal and facility-based factors affect Neonatal Intensive Care Unit (NICU) admission after cesarean delivery in northern Nigeria.

METHODS

A prospective cohort study involving 200 women undergoing cesarean section were consecutively enrolled with subsequent follow-up of their infants in the post-natal period. Data were abstracted from the medical record using an interviewer-administered questionnaire. The primary outcomes were NICU admission and intrauterine or early neonatal deaths. Binary logistic regression modelling was used to identify variables independently associated with the outcomes.

RESULTS

Over the study period (six months), there were 200 cesarean sections. A total of 30 (15.0%) neonates were admitted into the NICU following the procedure. No stillbirths or early neonatal deaths were recorded. NICU admission was associated with gestational age (preterm vs. term [adjusted odds ratio, aOR: 18.9, 95% confidence interval (CI): 4.0-90.4]), birth weight (small vs. appropriate [aOR: 6.7, 95% CI 1.9-22.7] and large vs. appropriate birth weight [aOR: 20.3, 95% CI 2.9-143.7]) and the number of indications for cesarean section (≥2 vs. one [aOR: 0.2, 95% 0.1-0.8]).

CONCLUSIONS

Prematurity, small and large for gestational age neonates; and indications for cesarean section were associated with increased likelihood of neonatal admission following cesarean delivery. These findings could inform ongoing quality enhancement initiatives to improve NICU admission outcomes at the study site, and other similar settings.

Facility and care provider emergency preparedness for neonatal resuscitation in Kano, Nigeria

Introduction

The knowledge, attitude, and practice of emergency neonatal resuscitation are critical requirements in any facility that offers obstetric and neonatal services. This study aims to conduct a needs assessment survey and obtain individual and facility-level data on expertise and readiness for neonatal resuscitation. We hypothesize that neonatal emergency preparedness among healthcare providers in Kano, Nigeria is associated with the level of knowledge, attitudinal disposition, practice and equipment availability at the facility level.

Methods

A semi-structured, self-administered questionnaire was administered to a cross-section of health providers directly involved with neonatal care (n = 112) and attending a neonatal resuscitation workshop in Kano state. Information regarding knowledge, attitude, practice and facility preparedness for neonatal resuscitation was obtained. Bloom’s cut-off score and a validated basic emergency obstetric and neonatal care assessment tool were adopted to categorize outcomes. Multivariable logistic regression was employed to determine independent predictors of knowledge and practice.

Results

Almost half (48% and 42% respectively) of the respondents reported average level of self-assessed knowledge and comfort during resuscitation. Only 7% (95% CI:3.2–13.7) and 5% (95% CI:2.0–11.4) of health providers demonstrated good knowledge and practice scores respectively, with an overall facility preparedness of 46%. Respondents’ profession as a physician compared to nurses and midwives predicted good knowledge (aOR = 0.08, 95% CI: 0.01–0.69; p = 0.01), but not practice.

Conclusion

Healthcare provider’s knowledge and practice including facility preparedness for emergency neonatal resuscitation were suboptimal, despite the respondents’ relatively high self-assessed attitudinal perception. Physicians demonstrated higher knowledge compared to other health professionals. The low level of respondents’ awareness, practice, and facility readiness suggest the current weak state of secondary health systems in Kano.

Dielectric Study of Gel Polymer Electrolyte Based on PVA-K2CO3-SiO2

In this study, effect of filler (SiO2) on dielectric and electrical properties of gel polymer electrolyte (GPE) based on PVA-K2CO3 has been investigated and reported. The electrolyte were prepared by incorporating silica particle as a filler into the un-plasticized electrolyte (PVA-K2CO3). The prepared electrolyte were characterized physicochemically (FTIR) and electrochemically based on electrochemical impedance spectroscopy (EIS). Based on the impedance spectroscopy, complex permittivity (ε*) (dielectric constant and loss) and complex electrical modulus (M*) (real and imaginary modulus) were calculated. Characterization result indicate that SiO2 particles has successfully interacts with PVA-K2CO3 in the form of a three dimensional polymeric network. At low frequencies, high values of complex permittivity (dielectric constant and dielectric loss) were observed, which increased with increasing temperature, signifying an increase in ionic conductivity of the electrolyte. With the incorporation of filler, the peaks of both ε* and M* shifts towards higher frequency side suggesting the speed up the relaxation time. From the electrical modulus, the developed electrolyte is shown to be highly capacitive in nature. Based on the peak shape of the imaginary part of electric modulus, the non-Debye type relaxation predicted. Analysis of both dielectric permittivity and electrical modulus suggest that ionic and polymer segmental motions are strongly coupled. An optimum ionic conductivity of 3.25 × 104 mScm1 was achieved at ambient temperature at a composition of 15 wt.% SiO2 (PKS15).

Societal awareness on neonatal hyperbilirubinemia: A systematic review and meta-analysis

Early recognition of neonatal hyperbilirubinemia is essential for prevention of bilirubin neurotoxicity and its long-term sequelae. High rates of home delivery in low- and middle-income countries (LMICs) as well as early discharge post-delivery (within 24hours) make community surveillance for neonatal hyperbilirubinemia highly important. Here, we performed a literature review to estimate the level of societal awareness of neonatal hyperbilirubinemia. We searched several databases for studies assessing the knowledge and awareness of neonatal hyperbilirubinemia. We retrieved 211 citations from 206 databases with five being in the grey literature. 52 selected articles were further reviewed. Data from these studies were then analyzed using Stata software (Statacorp® LLC Texas USA). We found that the pooled estimate of societal awareness of neonatal hyperbilirubinemia was 67% (95% confidence interval [CI]: 60, 74). There however was a publication bias (Begg test: P ≤ 0.01; Egger P = 0.06). Studies that scored or graded knowledge reported lower estimates [adjusted odds ratio (aOR) = -0.17; 95% CI: -0.32-0.02; P = 0.03]. Hospital location was an important determinant of awareness of complications [aOR = 0.30; 95% CI: 0.30-0.57; P = 0.03]. We therefore concluded that there is a significant need to improve societal awareness of neonatal hyperbilirubinemia.

Maternal Instruction About Jaundice and the Incidence of Acute Bilirubin Encephalopathy in Nigeria

OBJECTIVE

To evaluate whether teaching mothers about neonatal jaundice will decrease the incidence of acute bilirubin encephalopathy among infants admitted for jaundice.

STUDY DESIGN

This was a multicenter, before-after and cross-sectional study. Baseline incidences of encephalopathy were obtained at 4 collaborating medical centers between January 2014 and May 2015 (Phase 1). Structured jaundice instruction was then offered (May to November 2015; Phase 2) in antenatal clinics and postpartum. Descriptive statistics and logistic regression models compared 3 groups: 843 Phase 1 controls, 338 Phase 2 infants whose mothers received both antenatal and postnatal instruction (group A), and 215 Phase 2 infants whose mothers received no instruction (group B) either because the program was not offered to them or by choice.

RESULTS

Acute bilirubin encephalopathy occurred in 147 of 843 (17%) Phase 1 and 85 of 659 (13%) Phase 2 admissions, which included 63 of 215 (29%) group B and 5 of 338 (1.5%) group A infants. OR for having acute bilirubin encephalopathy, comparing group A and group B infants adjusted for confounding risk factors, was 0.12 (95% CI 0.03-0.60). Delayed care-seeking (defined as an admission total bilirubin ≥18 mg/dL at age ≥48 hours) was the strongest single predictor of acute bilirubin encephalopathy (OR 11.4; 6.6-19.5). Instruction decreased delay from 49% to 17%. Other major risk factors were home births (OR 2.67; 1.69-4.22) and hemolytic disease (hematocrit ≤35% plus bilirubin ≥20 mg/dL) (OR 3.03; 1.77-5.18). The greater rate of acute bilirubin encephalopathy with home vs hospital birth disappeared if mothers received jaundice instruction.

CONCLUSIONS

Providing information about jaundice to mothers was associated with a reduction in the incidence of bilirubin encephalopathy per hospital admission.

Macrogeographical variability in the great call of Hylobates agilis: assessing the applicability of vocal analysis in studies of fine-scale taxonomy of gibbons

Vocal characteristics have been used extensively to distinguish different taxonomic units of gibbons (family Hylobatidae). The agile gibbon (Hylobates agilis) has a disjunct distribution range in the Southeast Asian archipelago (remnants of the former Sunda landmass), and populations on different islands are currently recognized as distinct subspecies or even species. We recorded great calls from female agile gibbons from two populations on Sumatra and two populations on Borneo and examined the vocal variability on four levels: within-individuals, between-individuals, between-populations and between-islands. The primary objective was to evaluate the effect of geographical isolation on variability in song pattern and to test whether proposed island-specific song characteristics exist, reflecting evolutionary divergence between Sumatran and Bornean agile gibbons. One hundred great calls were recorded from 20 females and analyzed for 18 spectral and temporal acoustic parameters. Principal component analysis followed by a nested ANOVA on components revealed a complex pattern of song variability not likely to reflect taxonomic or evolutionary relationship. We found no evidence that Sumatran and Bornean agile gibbons have evolved different vocal characteristics, refuting a distinction between them based on vocal characteristics. A high level of plasticity was found in great calls from the same individual, and generally the inferred pattern of variability suggested that ecological or social factors may confound any genetically based island dialects.

A single transurethral Macroplastique injection as primary treatment for stress incontinence in women

The clinical records of 102 women were analysed to estimate the success rate of a single transurethral Macroplastique (Uroplasty BV, Netherlands) injection for the treatment of stress incontinence. We then compared the results of those who had had the injection as primary treatment (71/102) with those women who had undergone previous failed incontinence surgery (31/102). The overall success rate was 68% following a single injection of Macroplastique at a mean follow-up period of 3.2 months; the success rate was obtained by including all patients who were either cured or markedly improved requiring no further intervention. The success rate of those who had had previous surgery was 71% and for the primary treatment group it was 66%. This difference was not statistically significant. These results suggest a potential role of Macroplastique transurethral injection as primary treatment for genuine stress incontinence in women.

A multicentre evaluation of a new surgical technique for urethral bulking in the treatment of genuine stress incontinence

This prospective study assesses the surgeon and patient acceptability of a new implantation device for transurethral Macroplastique injection, as well as the safety and effectiveness of the technique. Ten women with genuine stress incontinence were recruited at each of four participating urogynaecological centres. Treatment was performed in an outpatient or day case setting and follow up took place at six weeks and three months after treatment. Those in whom treatment had failed were offered re-treatment. The operator acceptance of the device was rated as excellent or acceptable in 95% after the first treatment and 100% after re-treatment. Urethral insertions were rated acceptable in 92.5%. Pain was scored as mild to moderate in 89% of all insertions. The overall success rate was 74.3% at three months with an implantation rate of 1.35 which appears to be comparable to published endoscopic data. We have concluded from this study that the Macroplastique implantation device is safe to use and provides simplified, yet effective alternative to the endoscopic implantation of urethral bulking agents.

Cervical screening: management of patients referred for colposcopy with smear abnormalities less severe than dyskaryosis

The cervical smear and biopsy results were reviewed for 141 patients who were referred for colposcopy with either a technically unsuitable smear or with cervical smear abnormalities less severe than dyskaryosis. The number of referrals due to minor smear abnormalities more than doubled from 8.6% to 22.3% of the total colposcopy referrals over the 4 year period studied. The minor smear abnormalities were only associated with cervical intraepithelial neoplasia (CIN) in patients aged < 50 years. In 19 (13.5%) of the 141 patients high-grade lesions (CIN II or CIN III) were diagnosed. There were no cases of invasive cancer. Furthermore, the increased number of patients being referred for colposcopy with minor cervical smear abnormalities highlights the increasing pressures on colposcopy services, with prolonged waiting times for all patients.

Oral amino acids and gastric emptying: an investigation of the mechanism of levodopa-induced gastric stasis

To investigate possible mechanisms of levodopa-induced gastric stasis, we have studied the effect of other amino acids on gastric emptying. The large neutral amino acid tryptophan delays gastric emptying in the dog at molar concentrations below those required to stimulate duodenal osmoreceptors. In healthy volunteers, we have shown that neither tryptophan nor the small neutral amino acid glycine delayed gastric emptying when given in concentrations similar to those of levodopa which produce gastric stasis. The study suggests that levodopa does not inhibit gastric emptying by an effect on duodenal amino acid receptors or via osmoreceptors.