Health challenges in South Dakota: Creation of healthcare provider referral list for Special Olympic athletes

Special Olympics promotes the health of their athletes year-round and offers their athletes options to obtain free health screenings. Following screening events, athletes often have difficulties finding needed referral care. Obstacles to finding a healthcare provider (HCP) for a referral is what necessitates the need for a state-wide HCP referral list in South Dakota. Creation of a HCP referral list was done via an online two-part survey and sent to HCPs throughout the state of South Dakota. Currently, this is the only database of healthcare providers that is accessible to individuals with intellectual and developmental disabilities (IDD) that are members of Special Olympics South Dakota (SOSD). While the created referral list offers increased opportunities to access HCPs in South Dakota, there are still limits to ensuring easy access to HCPs throughout the entire state.

Acceptance and Tolerability of Helmet CPAP in Pediatric Bronchiolitis and Pneumonia: A Feasibility Study

Continuous positive airway pressure (CPAP) is a form of non-invasive ventilation used to support pediatric patients with acute respiratory infections. Traditional CPAP interfaces have been associated with inadequate seal, mucocutaneous injury, and aerosolization of infectious particles. The helmet interface may be advantageous given its ability to create a complete seal, avoid skin breakdown, and decrease aerosolization of viruses. We aim to measure tolerability and safety in a pediatric population in the United States and ascertain feedback from parents and health care providers. We performed a prospective, open-label, single-armed feasibility study to assess tolerability and safety of helmet CPAP. Pediatric patients 1 month to 5 years of age admitted to the pediatric intensive care unit with pulmonary infections who were on CPAP for at least 2 hours were eligible. The primary outcome was percentage of patients tolerating helmet CPAP for 4 hours. Secondary measures included the rate of adverse events and change in vital signs. Qualitative feedback was obtained from families, nurses, and respiratory therapists. Five patients were enrolled and 100% tolerated helmet CPAP the full 4-hour study period. No adverse events or significant vital sign changes were observed. All family members preferred to continue the helmet interface, nursing staff noted it made cares easier, and respiratory therapists felt the set up was easy. Helmet CPAP in pediatric patients is well-tolerated, safe, and accepted by medical staff and families in the United States future randomized controlled trials measuring its effectiveness compared with traditional CPAP interfaces are needed.

An exploratory assessment of the management of pediatric traumatic brain injury in three centers in Africa

PURPOSE

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in low- and middle-income countries (LMICs). Hospital care practices of pediatric TBI patients in LMICs are unknown. Our objective was to report on hospital management and outcomes of children with TBI in three centers in LMICs.

METHODS

We completed a secondary analysis of a prospective observational study in children (<18 years) over a 4-week period. Outcome was determined by Pediatric Cerebral Performance Category (PCPC) score; an unfavorable score was defined as PCPC > 2 or an increase of two points from baseline. Data were compared using Chi-square and Wilcoxon rank sum tests.

RESULTS

Fifty-six children presented with TBI (age 0-17 y), most commonly due to falls (43%, n = 24). Emergency department Glasgow Coma Scale scores were ≤ 8 in 21% (n = 12). Head computed tomography was performed in 79% (n = 44) of patients. Forty (71%) children were admitted to the hospital, 25 (63%) of whom were treated for suspected intracranial hypertension. Intracranial pressure monitoring was unavailable. Five (9%, n = 5) children died and 10 (28%, n = 36) inpatient survivors had a newly diagnosed unfavorable outcome on discharge.

CONCLUSION

Inpatient management and monitoring capability of pediatric TBI patients in 3 LMIC-based tertiary hospitals was varied. Results support the need for prospective studies to inform development of evidence-based TBI management guidelines tailored to the unique needs and resources in LMICs.

Continuous positive airway pressure in managing acute respiratory distress in children in district hospitals: evidence for scale-up

In children, acute respiratory distress (ARD) is a clinical presentation requiring emergency management, including mechanical ventilation. Mechanical ventilators are lacking in sub-Saharan Africa. Continuous Positive Airway Pressure (CPAP) is an alternative form of non-invasive respiratory support that has been used in high-income countries for over four decades. Its use in sub-Saharan Africa is, however, limited and often restricted to neonates. Controlled trials in Ghana have shown that the use of CPAP in children younger aged 1–12 months reduces 2-week all-cause mortality from ARD by 60% (RR 0·40, 0·19–0·82; p=0·01). The absolute reduction in mortality of 4% implies one infant life saved for every 25 children treated with CPAP. This paper reviews the findings of the trials in Ghana and contrasts the findings with those of trials in Bangladesh and Malawi. It makes the case that implementation research (rather than more controlled trials) is now needed to support the routine, safe and effective use of CPAP in managing ARD in older infants in district hospitals in Ghana.

Reversible Coronary Artery Aneurysm With Delayed Anti-inflammatory Therapy in Multisystem Inflammatory Syndrome in Children

A 4-year-old boy with multisystem inflammatory syndrome in children before widespread recognition of this disease developed complications, including coronary artery aneurysm, without anti-inflammatory treatment. With delayed treatment, all sequelae resolved. This case demonstrates a natural history supporting the role of anti-inflammatory treatment even with delayed or equivocal diagnosis. (Level of Difficulty: Intermediate.)

COVID-19 Cliff Notes: A COVID-19 Multidisciplinary Care Compendium

As we pass the nearly 9 month mark of the coronavirus virus disease 2019 (COVID-19) pandemic in the United States, we sought to compile a brief multi-disciplinary compendium of COVID-19 information learned to date. COVID-19 is an active viral pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that confers high morbidity and mortality. COVID-19 has been associated with: pulmonary compromise and acute respiratory distress syndrome, thrombotic events, inflammation and cytokine, and post-infectious syndromes. Mitigation of these complications and expeditious therapy are a global urgency; this is brief summary of current data and management approaches synthesized from publications, experience, cross-disciplinary expertise (Figure 1).

Human Rhinovirus/Enterovirus in Pediatric Acute Respiratory Distress Syndrome

The role of human rhinovirus/enterovirus (HRV/HEV) in severe lower respiratory tract infections remains unclear. We characterized the respiratory status of children admitted to a large academic pediatric intensive care unit (PICU) who tested positive for only HRV/HEV. One hundred and fifty-five children met inclusion criteria with 62% requiring positive pressure respiratory support of 5 cm of water pressure or more within the first 24 hours of admission. Among them, 34% had SaO ₂ to FiO ₂ ratios of 264 or less with 22 patients (14%) meeting criteria for pediatric acute respiratory distress syndrome. HRV/HEV is associated with significant respiratory disease in children admitted to the PICU.

Contribution of Host Immune Responses Against Influenza D Virus Infection Toward Secondary Bacterial Infection in a Mouse Model

Influenza D viruses (IDV) are known to co-circulate with viral and bacterial pathogens in cattle and other ruminants. Currently, there is limited knowledge regarding host responses to IDV infection and whether IDV infection affects host susceptibility to secondary bacterial infections. To begin to address this gap in knowledge, the current study utilized a combination of in vivo and in vitro approaches to evaluate host cellular responses against primary IDV infection and secondary bacterial infection with Staphylococcus aureus (S. aureus). Primary IDV infection in mice did not result in clinical signs of disease and it did not enhance the susceptibility to secondary S. aureus infection. Rather, IDV infection appeared to protect mice from the usual clinical features of secondary bacterial infection, as demonstrated by improved weight loss, survival, and recovery when compared to S. aureus infection alone. We found a notable increase in IFN-β expression following IDV infection while utilizing human alveolar epithelial A549 cells to analyze early anti-viral responses to IDV infection. These results demonstrate for the first time that IDV infection does not increase the susceptibility to secondary bacterial infection with S. aureus, with evidence that anti-viral immune responses during IDV infection might protect the host against these potentially deadly outcomes.

Effective training-of-trainers model for the introduction of continuous positive airway pressure for neonatal and paediatric patients in Kenya

Background: Continuous positive airway pressure (CPAP) is a relatively low-cost technology which can improve outcome in neonatal and paediatric patients with respiratory distress. Prior work in a lower middle-income country demonstrated degradation of CPAP skills and knowledge after the initial training. Aims: To determine if a training-of-trainers (ToT) curriculum can decrease gaps in skills and knowledge between first-generation (trained by a United States physician and nurse) and second-generation healthcare providers (trained by local trainers) in Kenya, and to describe the usage pattern, outcome and safety in patients who received CPAP following the trainings. Methods: The first day of training entailed didactic and simulation sessions. On the second day participants were taught how to train others to use CPAP. First- and second-generation healthcare providers were tested on their skills and knowledge. Unpaired t-tests were used to test for equivalence. Prospective data on CPAP usage was collected following the initial trainings. Results: 37 first-generation healthcare providers (16 nurses; 21 physicians, medical/clinical officers) were trained as trainers and 40 second-generation healthcare providers (19 nurses, 21 physicians, medical/clinical officers) trained by first-generation healthcare providers were available for skills and knowledge testing. There were no statistically significant differences between first- and second-generation healthcare providers' skills (90%, 95% CI 87-93 vs 89%, 95% CI 86-92) or knowledge scores (91%, 95% CI 88-93 vs 90%, 95% CI 88-93). A total of 1111 patients were placed on CPAP mostly by nurses (61%), prematurity/acute respiratory distress syndrome was the most common indication, nasal injury/bleeding (2%) was the most common reported adverse event, and the overall mortality rate was 24%. Conclusion: The ToT model was successful, nurses initiated CPAP most commonly, prematurity with acute respiratory distress syndrome was the most common indication, and adverse events were uncommon.

Impact of a Clinical Trial in Two District Hospitals in Ghana: Perspectives of Ghanaian Researchers

Conducting clinical trials in resource-poor settings may contribute to local capacity building. We describe the perspectives of local research personnel regarding the impact of collaborating in a clinical trial in rural Ghana. Forty-six Ghanaian research personnel were eligible to complete an anonymous survey, and 35 (76%) participated. Of the 35 respondents, 32 (91%) agreed that future patients will benefit because the hospital was part of the study. All 35 respondents reported a personal benefit derived from study involvement, most commonly citing skills or knowledge gained. Of the 35 individuals, 21 reported one or more burdens, most commonly citing nonspecific research responsibilities. Our data support the hypothesis that participation in clinical trials can contribute to capacity building in district hospitals in a lower middle-income country.

Respiratory Pathogens in Children 1 Month to 5 Years of Age Presenting With Undifferentiated Acute Respiratory Distress in 2 District-Level Hospitals in Ghana

Ghanaian children (2176) aged <5 years who presented with undifferentiated acute respiratory distress were tested for respiratory pathogens using a BioFire FilmArray polymerase chain reaction assay. Rhinovirus and/or enterovirus was detected in 36% of the assays, respiratory syncytial virus in 11%, and parainfluenza in 7%. Respiratory syncytial virus and metapneumovirus were detected more frequently in the rainy season than in the dry season.

Development and Implementation of a Training-of-Trainers Program for Continuous Positive Airway Pressure in Neonatal and Pediatric Patients in Five Low- and Middle-Income Countries

We describe a pragmatic training-of-trainers program for the use of continuous positive airway pressure (CPAP) for neonatal and pediatric patients. The program is designed for medical professionals working in low- and middle-income countries and involves 2 days of in-class training followed by 1 day of in-service training. The program was created after training in Cambodia, Ghana, Honduras, Kenya and Rwanda and addresses the issues of resource availability, cultural context and local buy-in and partnership in low- and middle-income countries. We hope others will use the training program to increase knowledge and use of CPAP with the ultimate goal of improving neonatal and pediatric survival globally.

Aftermath of a clinical trial: evaluating the sustainability of a medical device intervention in Ghana

A randomized controlled trial recently demonstrated that continuous positive airway pressure (CPAP) effectively decreases respiratory rate in children presenting to Ghanaian district hospitals with respiratory distress. A follow-up study 16 months later evaluated the extent to which the skills and equipment necessary for CPAP use have been maintained. Seven of eight CPAP machines were functional, but five of eight oxygen concentrators and three of four electric generators were non-functional. Nurses trained by US study personnel (first-generation) and nurses trained by Ghanaian nurses after the study (second-generation) were evaluated on CPAP knowledge and skills. Twenty-eight nurses participated in the study, 9 first-generation and 19 second-generation. First-generation trainees scored significantly higher than second-generation trainees on both skills and knowledge assessments (p = 0.003). Appropriate technical support and training must be ensured to address equipment maintenance. Protocolization of the training program, in conjunction with skills and knowledge assessment, may improve acquisition and retention among second- and future-generation trainees.

Transplacentally transferred functional antibodies against Plasmodium falciparum decrease with age

Transplacental transfer of antibodies from clinically malaria immune pregnant women to their fetuses is thought to provide passive protection against malaria during infancy. However, the presences and duration of functional antibodies against Plasmodium falciparum (Pf) in newborns has not been described. We used growth inhibition assays (GIA) to measure total anti-malaria functional antibodies present at birth and over the following year. Samples were drawn from cord blood (n=86) and in infants at six and 12 months of life (n=86 and 65 respectively). Three laboratory Pf strains (D10, W2mef, 3D7) and a field isolate (Msambweni 2006) were used in the assays. Median (ranges) GIA levels for cord plasma differed between laboratory parasite strains: D10, 0% (0-81); W2mef, 6% (0-80); 3D7, 18% (0-88); Msambweni 2006, 6% (0-43) (P<0.001, Wilcoxon signed-rank test). GIA levels against all Pf strains were found to decline in infants from birth to six months (P<0.01, Wilcoxon, signed-rank test). Functional antibodies as measured by GIA are transferred to the fetus and wane in the infants over time. Infant protection from clinical malaria disease may in part be mediated by these functional anti-malaria antibodies.

Frequency-domain interferometric second-harmonic spectroscopy

We report a new spectroscopic technique to measure simultaneously the intensity and the phase of second-harmonic (SH) radiation over a broad spectral range without laser tuning. Temporally separated SH pulses from two sources, excited by the same broad-bandwidth 15-fs Ti:sapphire fundamental pulse, interfere in a spectrometer to yield frequency-domain interference fringes. We demonstrate the technique by measuring the strongly bias-dependent phase of SH radiation from a Si/SiO(2)/Cr metal-oxide-semiconductor capacitor in the spectral range of the SiE(1) critical point.

Receptor-mediated activation of Gsalpha: evidence for intramolecular signal transduction

To investigate the mechanism by which cell surface receptors activate heterotrimeric G proteins, we applied a scanning mutagenesis approach to the carboxyl-terminal 40% of alphas (residues 236-394) to identify residues that play a role in receptor-mediated activation. We identified four regions of sequence in which mutations significantly impaired receptor-dependent stimulation of cAMP synthesis in transiently transfected cyc- S49 lymphoma cells, which lack endogenous alphas. Residues at the carboxyl terminus are likely to be receptor contact sites. Buried residues near the bound GDP are connected to the carboxyl terminus by an alpha helix and may regulate GDP affinity. Residues in two adjacent loops of the GTPase domain at the interface with the helical domain, one of which includes a region, switch III, that changes conformation on GTP binding, are positioned to relay the receptor-initiated signal across the domain interface to facilitate GDP release. Consistent with this hypothesis, replacing the helical domain of alphas with that of alphai2 in an alphas/alphai2/alphas chimera corrects the defect in receptor-mediated activation caused by alphai2 substitutions on the GTPase side of the interface. Thus, complementary interactions between residues across the domain interface seem to play a role in receptor-catalyzed activation.

Plasma membrane localization of G alpha z requires two signals

Three covalent attachments anchor heterotrimeric G proteins to cellular membranes: the alpha subunits are myristoylated and/or palmitoylated, whereas the gamma chain is prenylated. Despite the essential role of these modifications in membrane attachment, it is not clear how they cooperate to specify G protein localization at the plasma membrane, where the G protein relays signals from cell surface receptors to intracellular effector molecules. To explore this question, we studied the effects of mutations that prevent myristoylation and/or palmitoylation of an epitope-labeled alpha subunit, alpha z. Wild-type alpha z (alpha z-WT) localizes specifically at the plasma membrane. A mutant that incorporates only myristate is mistargeted to intracellular membranes, in addition to the plasma membrane, but transduces hormonal signals as well as does alpha z-WT. Removal of the myristoylation site produced a mutant alpha z that is located in the cytosol, is not efficiently palmitoylated, and does not relay the hormonal signal. Coexpression of beta gamma with this myristoylation defective mutant transfers it to the plasma membrane, promotes its palmitoylation, and enables it to transmit hormonal signals. Pulse-chase experiments show that the palmitate attached to this myristoylation-defective mutant turns over much more rapidly than does palmitate on alpha z-WT, and that the rate of turnover is further accelerated by receptor activation. In contrast, receptor activation does not increase the slow rate of palmitate turnover on alpha z-WT. Together these results suggest that myristate and beta gamma promote stable association with membranes not only by providing hydrophobicity, but also by stabilizing attachment of palmitate. Moreover, palmitoylation confers on alpha z specific localization at the plasma membrane.

Femtosecond carrier-induced screening of dc electric-field-induced second-harmonic generation at the Si(001) SiO(2) interface

Carrier-induced screening of the dc electric field at the Si(001)-SiO(2) interface is observed by intensity-dependent and femtosecond-time-resolved second-harmonic spectroscopy. The screening occurs on a time scale of ~?(p)(-1) , the reciprocal plasma frequency of the generated carriers.

Fatty acylation of alpha z. Effects of palmitoylation and myristoylation on alpha z signaling

As the first step in an investigation of roles played by fatty acylation of G protein alpha chains in membrane targeting and signal transmission, we inserted monoclonal antibody epitopes, hemagglutinin (HA) or Glu-Glu (EE), at two internal sites in three alpha subunits. At site I, only HA-tagged alpha q and alpha z functioned normally. alpha s, alpha q, and alpha z subunits tagged at site II with the EE epitope showed normal expression, membrane localization, and signaling activity. Using epitope-tagged alpha z, we investigated effects of mutations in sites for fatty acylation. Mutational substitution of Ala for Gly2 (G2A) prevented incorporation of myristate and decreased but did not abolish incorporation of palmitate. Substitution of Ala for Cys3 (C3A) prevented incorporation of palmitate but had no effect on incorporation of myristate. Substitution of Ala for both Gly2 and Cys3 (G2AC3A) prevented incorporation of both myristate and palmitate. All three mutations substantially disrupted association of alpha z with the particulate fraction. Gz-mediated inhibition of adenylyl cyclase, triggered by activation of the D2-dopamine receptor, was, respectively, abolished (G2AC3A), impaired (G2A), and enhanced (C3A). Constitutive inhibition of adenylyl cyclase by alpha z was unchanged (G2AC3A), strongly diminished (G2A), or strongly enhanced (C3A). A nonacylated, mutationally activated alpha z mutant inhibited adenylyl cyclase, although less potently than normally acylated, mutationally activated alpha z. From these findings we conclude: (a) fatty acylations of alpha z increase its association with membranes; (b) myristoylation is not required for palmitoylation of alpha z or for its productive interactions with adenylyl cyclase; (c) palmitoylation is not required for, but may instead inhibit, signaling by alpha z.

Lipid modifications of trimeric G proteins

G protein alpha subunits and beta gamma dimers are covalently modified by lipids. The emerging picture is one in which attached lipids provide more than just a nonspecific "glue" for sticking G proteins to membranes. We are only beginning to understand how different lipid modifications of different G protein subunits affect specific protein-protein interactions and localization to specific cellular sites. In addition, regulation of these modifications, particularly palmitoylation, can provide new ways to regulate signals transmitted by G proteins.

Palmitoylation is required for signaling functions and membrane attachment of Gq alpha and Gs alpha

We have identified the palmitoylated cysteine residues of alpha q and alpha s, alpha subunits of two heterotrimeric G proteins. Mutational substitutions of serines for cysteines 9 and 10 in alpha q and cysteine 3 in alpha s profoundly alter behavior of the subunits expressed in HEK293 cells. Neither mutant alpha subunit incorporates palmitate; both mutant proteins are found in the soluble rather than the particulate fraction; mutant alpha q or alpha s cannot couple a co-expressed receptor to stimulation of phospholipase C or adenylylcyclase, respectively; cysteine substitution prevents a mutationally activated alpha q (R183C) from stimulating phospholipase C directly, and reduces but does not abolish the ability of a similarly activated alpha s (R201C) to stimulate cAMP synthesis. Substitution of a myristoylation sequence for the palmitoylation sites leads to labeling of alpha q and alpha s by myristate, rather than by palmitate. Myristoylation restores the abilities of both nonpalmitoylated alpha q and alpha s to attach to membranes and, in the case of alpha q, restores its ability to stimulate phospholipase C, whether triggered by the R183C mutation or by receptor activation. These findings identify palmitoylation as a critical determinant of membrane attachment for alpha q and alpha s and show that this modification is required for normal signaling by these proteins.

An audit of extradural infusion analgesia in children using bupivacaine and diamorphine

One hundred and fifty extradural infusions of diamorphine and bupivacaine after major surgery in children were audited over a 15 month period. The majority of the children (69%) were less than 5 years of age. Analgesia was assessed or self-rated as 'very good' in over 75% of patients. Urinary retention was seen in 11% of patients and pruritus in 10%. Respiratory depression requiring intervention was only seen in one patient--a premature infant of 39 weeks post-conceptual age. Technical complications resulted in the early loss of 16.7% of the infusions. Although analgesia was good the complexity of the extradural infusion technique demanded significant medical and nursing time especially to overcome technical problems.

Monoclonal antibodies directed against a synthetic peptide corresponding to the alpha-bungarotoxin binding region of the acetylcholine receptor

Murine monoclonal antibodies have been produced against a 32 amino acid synthetic peptide corresponding to residues 173-204 on the alpha-subunit of the nicotinic acetylcholine receptor from Torpedo californica. All of the monoclonal antibodies were of the IgM subtype and most cross-reacted with the purified native receptor. None of the antibodies were effective in blocking alpha-bungarotoxin binding to the receptor nor, conversely, did alpha-bungarotoxin interfere with antibody binding. However, two monoclonal antibodies, previously shown to bind near the ligand binding site on the native receptor, did compete partially (50%) with the binding of one of the IgM monoclonal antibodies.

Distribution of alpha-bungarotoxin binding sites over residues 173-204 of the alpha subunit of the acetylcholine receptor

The binding of alpha-bungarotoxin to several synthetic peptides comprising different segments of the region 173-204 of the alpha subunit of the Torpedo acetylcholine receptor was investigated to further localize the neurotoxin-binding site on the primary sequence. When tested in a solid phase microwell assay system, a 32-amino acid peptide corresponding to residues 173-204 (32-mer) bound 125I-alpha-bungarotoxin with the same affinity (4.2 x 10(-8) M as determined from IC50 values) as the isolated alpha subunit (4.6 x 10(-8) M). The relative affinities of other antagonists (alpha-cobratoxin, d-tubocurarine) maintained the same rank order in this assay system as has been demonstrated with the intact receptor. Agonists competed with binding of toxin at millimolar concentrations but lost all rank order of potency. These findings demonstrate that peptide 173-204 contains many of the antagonist-binding determinants present on denatured alpha subunit but has lost specificity of agonist binding. To further localize the toxin-binding site, alpha-bungarotoxin binding to seven shorter peptides corresponding to portions of the 32-mer was investigated. 125I-alpha-Bungarotoxin bound to alpha subunit peptides 179-192, 181-198, 185-196, 186-196, and 193-204, but not to alpha subunit peptides 173-180 and 194-204. In a second assay, all of the peptides competed with binding of 125I-acetylcholine receptor to immobilized alpha-bungarotoxin. The apparent affinity was highest for the 173-204 32-mer (1.4 x 10(-7) M) and lowest for peptides 173-180 and 194-204 (greater than 10(-4) M). The affinity of the other peptides was intermediate (approximately 10(-5) M) and about 100-fold less than that of the 32-mer. The affinity of alpha-bungarotoxin was 3.5 x 10(-10) M, of isolated, native acetylcholine receptor, 3.2 x 10(-9) M, and of isolated denatured subunit, 1.2 x 10(-8) M, with this assay. The retention of some toxin-binding capacity by the shorter peptides indicates toxin-binding determinants are distributed over the entire length of the 32-mer. The determinants with higher affinity are located in the central region of the 32-mer between residues 179 and 196.

Binding of alpha-bungarotoxin to synthetic peptides corresponding to residues 173-204 of the alpha subunit of Torpedo, calf, and human acetylcholine receptor and restoration of high-affinity binding by sodium dodecyl sulfate

In order to investigate structure-function relationships of a segment of the acetylcholine receptor alpha subunit, binding of alpha-bungarotoxin to synthetic peptides corresponding to residues 173-204 of Torpedo, calf, and human alpha subunits was compared using a solid-phase radioassay. The affinities of 125I-alpha-bungarotoxin for the calf and human peptides were 15- and 150-fold less, respectively, than for the Torpedo peptide. On the basis of nonconservative substitutions in the calf and human sequences, aromatic residues (Tyr-181, Trp-187, and Tyr-189) are important for the higher affinity binding of the Torpedo peptide. Substitution of negatively charged Glu-180 with uncharged Gln in the calf peptide did not significantly affect toxin binding, indicating Glu-180 alone does not comprise the anionic subsite on the receptor to which the cationic quaternary ammonium groups of cholinergic agents bind. d-Tubocurarine competed toxin binding to the modified calf 32-mer which lacks Glu-180 and Asp-195 present in Torpedo. Thus, the negative subsite could be formed by another negatively charged residue or by more than one amino acid side chain. It is possible that the positive charges on cholinergic ligands are countered by a negative electrostatic potential provided by polar groups, such as the hydroxyl group of tyrosine, present on several residues in this region, and the negative charges present on any of residues 175, 180, 195, or 200. Equilibrium saturation binding of alpha-bungarotoxin to Torpedo peptide 173-204 revealed a minor binding component with an apparent KD of 4.2 nM and a major component with a KD of 63 nM.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthetic peptides corresponding to sequences of snake venom neurotoxins and rabies virus glycoprotein bind to the nicotinic acetylcholine receptor

Peptides corresponding to portions of loop 2 of snake venom curare-mimetic neurotoxins and to a structurally similar region of rabies virus glycoprotein were synthesized. Interaction of these peptides with purified Torpedo electric organ acetylcholine receptor was tested by measuring their ability to block the binding of 125I-labeled alpha-bungarotoxin to the receptor. In addition, inhibition of alpha-bungarotoxin binding to a 32-residue synthetic peptide corresponding to positions 173-204 of the alpha-subunit was determined. Neurotoxin and glycoprotein peptides corresponding to toxin loop 2 inhibited labeled toxin binding to the receptor with IC50 values comparable to those of nicotine and the competitive antagonist d-tubocurarine and to the alpha-subunit peptides with apparent affinities between those of d-tubocurarine and alpha-cobratoxin. Substitution of neurotoxin residue Arg37, the proposed counterpart of the quaternary ammonium of acetylcholine, with a negatively charged Glu residue reduced the apparent affinity about 10-fold. Peptides containing the neurotoxin invariant residue Trp29 and 10- to 100-fold higher affinities than peptides lacking this residue. These results demonstrate that relatively short synthetic peptides retain some of the binding ability of the native protein from which they are derived, indicating that such peptides are useful in the study of protein-protein interactions. The ability of the peptides to compete alpha-bungarotoxin binding to the receptor with apparent affinities comparable to those of other cholinergic ligands indicates that loop 2 of the neurotoxins and the structurally similar segment of the rabies virus glycoprotein act as recognition sites for the acetylcholine receptor. Invariant toxin residues Arg37 and Trp29 and their viral homologs play important, although not essential, roles in binding, possibly by interaction with complementary anionic and hydrophobic subsites on the acetylcholine receptor. The alpha-subunit peptide most likely contains all of the determinants for binding of the toxin and glycoprotein peptides present on the alpha-subunit, because these peptides bind to the 32-residue alpha-subunit peptide with the same or greater affinity as to the intact subunit.

Binding of rabies virus to purified Torpedo acetylcholine receptor

The binding of 125I- and 35S-labeled rabies virus (CVS strain) to affinity-purified acetylcholine receptor from Torpedo electric organ was demonstrated. The binding of rabies virus to the acetylcholine receptor increased with increasing receptor concentration, was dependent on the pH of the incubation medium, and was saturable with increasing virus concentration. Binding of radioactively labeled virus was effectively competed by unlabeled homologous virus particles. Binding of 35S-labeled rabies virus to the AChR was inhibited up to 50% by alpha-bungarotoxin and up to 30% by (+)-tubocurarine but was not affected by atropine. These results demonstrate direct binding of rabies virus to a well-defined neurotransmitter receptor, namely the acetylcholine receptor and indicate that at least a portion of the virus interaction occurs near the acetylcholine binding site on the receptor. These findings support the hypothesis that the acetylcholine receptor may serve as a rabies virus receptor in vivo.

Alpha-bungarotoxin binding to a high molecular weight component from lower vertebrate brain identified on dodecyl sulfate protein-blots

The binding of [125I]iodo-alpha-bungarotoxin [( 125]alpha-BuTX) to the dissociated alpha-subunit of Torpedo acetylcholine receptor (AChR) can be readily demonstrated in a modified 'protein-blot' analysis utilizing electrophoretically transferred, dissociated subunits immobilized onto positively charged nylon membranes which are then incubated directly with [125I]alpha-BuTX. We report here the use of the protein-blotting technique to detect the alpha-BuTX binding site present in the central nervous system of lower vertebrates and to characterize some of the physicochemical properties of the toxin binding site. High molecular weight (Mr greater than or equal to 200,000 and greater than or equal to 120,000) alpha-BuTX-binding components can be readily demonstrated in avian and fish brain extracts upon protein-blotting with [125I]alpha-BuTX following lithium dodecyl sulfate PAGE. Neither extensive reduction with dithiothreitol nor prior reduction followed by alkylation with iodoacetamide alter the mobility of the CNS-derived BuTX-binding sites. In contrast to our findings with Torpedo AChR or muscle AChR derived from a number of different species, no binding is observed in the molecular weight range of the alpha-subunit (Mr = 40,000) nor is any binding at any molecular weight observed in similar fractions prepared from adult, mammalian (rat, guinea pig) brain using this technique. These results demonstrate the existence in lower vertebrate brain of a BuTX binding site comparable in size to the AChR oligomeric complex of electric organ and muscle. They also suggest, however, striking structural differences between muscle AChR and the central neuronal BuTX-binding complex as well as a considerable difference between the neuronal BuTX-binding sites derived from lower and higher vertebrate brain.

Determination of the primary amino acid sequence specifying the alpha-bungarotoxin binding site on the alpha subunit of the acetylcholine receptor from Torpedo californica

A region of the alpha subunit of the nicotinic acetylcholine receptor containing the alpha-bungarotoxin-binding domain was mapped on the primary amino acid sequence in relation to asparagine-141, the presumed site of N-linked glycosylation. Proteolytic fragments of the alpha subunit, immobilized onto positively charged membrane filters, that bind 125I-labeled bungarotoxin were further analyzed on the basis of the size of the fragments and the presence of asparagine-141 as determined by susceptibility to digestion with endoglycosidase H. The bungarotoxin-binding site was found not to reside between amino acid residues 1 and 140 since bungarotoxin-binding fragments that are considerably larger than 140 amino acids and lack N-linked oligosaccharide chains were detected. The size of the smallest bungarotoxin-binding fragment containing asparagine-141 and the size of fragments produced by digestion with V8 protease further indicated that the bungarotoxin-binding site is contained within amino acid residues 153-241. A 32-amino acid synthetic peptide comprising a portion of this region (residues 173-204) was tested for its ability to bind 125I-labeled bungarotoxin. 125I-labeled bungarotoxin bound to the peptide and was competed by unlabeled bungarotoxin and d-tubocurarine with IC50 values of 0.5 microM and 2 mM, respectively. We conclude that a major determinant of the bungarotoxin-binding site on the alpha subunit resides between residues 173 and 204.

Amino acid sequence similarity between rabies virus glycoprotein and snake venom curaremimetic neurotoxins

Evidence was presented earlier that a host-cell receptor for the highly neurotropic rabies virus might be the acetylcholine receptor. The amino acid sequence of the glycoprotein of rabies virus was compared by computer analysis with that of snake venom curaremimetic neurotoxins, potent ligands of the acetylcholine receptor. A statistically significant sequence relation was found between a segment of the rabies glycoprotein and the entire sequence of long neurotoxins. The greatest identity occurs with residues considered most important in neurotoxicity, including those interacting with the acetylcholine binding site of the acetylcholine receptor. Because of the similarity between the glycoprotein and the receptor-binding region of the neurotoxins, this region of the viral glycoprotein may function as a recognition site for the acetylcholine receptor. Direct binding of the rabies virus glycoprotein to the acetylcholine receptor could contribute to the neurotropism of this virus.

Binding of alpha-bungarotoxin to proteolytic fragments of the alpha subunit of Torpedo acetylcholine receptor analyzed by protein transfer on positively charged membrane filters

Proteolytic fragments of the alpha subunit of the acetylcholine receptor retain the ability to bind alpha-bungarotoxin following resolution by polyacrylamide gel electrophoresis and immobilization on protein transfers. The alpha subunit of the acetylcholine receptor of Torpedo electric organ was digested with four proteases: Staphylococcus aureus V-8 protease, papain, bromelain, and proteinase K. The proteolytic fragments resolved on 15% polyacrylamide gels were electrophoretically transferred onto positively charged nylon membrane filters. When incubated with 0.3 nM 125I-labeled alpha-bungarotoxin and autoradiographed, the transfers yielded patterns of labeled bands characteristic for each protease. The molecular masses of the fragments binding toxin ranged from 7 to 34 kDa, with major groupings in the 8-, 18-, and 28-kDa ranges. The apparent affinity of the fragments for alpha-bungarotoxin as determined from the IC50 value was 6.7 X 10(-8) M. The labeling of fragments with alpha-bungarotoxin could be inhibited by prior affinity alkylation of receptor-containing membranes with 4-(N-maleimido)-alpha-benzyltrimethylammonium iodide. These findings demonstrate that immobilized proteolytic fragments as small as 1/5 the size of the alpha subunit retain the structural characteristics necessary for binding alpha-bungarotoxin, although the toxin is bound to the fragments with lower affinity than to the native receptor. The effect of affinity ligand alkylation demonstrates that the alpha-bungarotoxin binding site detected on the proteolytic fragments is the same as the affinity-labeled acetylcholine binding site on the intact acetylcholine receptor.

Results of the 1976 APA Self-Assessment Program

The authors describe the development and implementation of the third edition of the Psychiatric Knowledge and Skills Self-Assessment Program (PKSAP-III). An assessment of the performance of 4,137 participants in PKSAP-III according to their primary professional activity, time spent in continuing medical education (CME), Board certification, and geographical area reveal that participation in CME had a positive effect on test performance. The authors conclude that the PKSAP is most valuable as a diagnostic tool for the individual practitioner and as a resources tool to assist in structuring a curriculum for small group discussions.

Excess volumes of dimethyl sulphoxide mixtures

The volumes of mixing (excess volumes) for dimethyl sulphoxide with carbon tetrachloride, chloroform, benzene, acetone, and water have been measured at 25.00� and 35.00� with a dilatometer. The values for the equimolar mixtures at 25.000 are -0.596, -0.112, -0.304, -0.511, and -0.944 cm3 mol-1 respectively. The results are compared with available density measurements on these systems and qualitatively compared with the corresponding acetone systems.