0929 Caregiver-Reported Versus Clinician-Documented Child Sleep Problems and Sleep-Related Health Behaviors in Primary Care

Introduction

Sleep problems are highly prevalent in early childhood but often under-identified in pediatric primary care. This study identified the prevalence of caregiver-reported versus primary care provider (PCP)-documented sleep problems and sleep-related health behaviors in young children presenting to well child visits (WCVs).

Methods

Caregivers (85.4% mothers) of 198 young children (2-5 years, M = 3.3, 53.7% female, 62.9% Black) presenting to urban (74.1%) and suburban (25.9%) primary care sites for well child visits (WCVs) completed research surveys on child behavioral sleep problems, snoring, and sleep-related health behaviors (e.g., caffeine consumption) on the day of their child’s WCV. Electronic medical record review was used to identify the rate of PCP-documented sleep problems and related recommendations in the WCV progress note.

Results

Fifteen percent of caregivers reported a child sleep problem according to questionnaire data, which did not significantly differ from the 12.0% of children with a PCP-documented sleep problem in the WCV progress note (p = .31). However, significantly more caregivers (28.3%) reported bedtime difficulties (resistance; tantrums) on questionnaires (p <.001), which were not captured in the 12.0% of WCVs noting sleep problems. A total of 8% of WCVs included child sleep recommendations. Child snoring was reported by 17.0% of caregivers, but was less frequently documented in WCVs (4.5%, p <.001). Although many caregivers reported poor child sleep-related health behaviors, including daily child caffeine consumption (21.1%) and bedroom electronics (62.9%), significantly fewer PCPs documented these issues (caffeine: 2.0%; electronics: 6.6%) or related recommendations (decrease caffeine: 1.0%; eliminate electronics: 3.5%) in the progress note (all p-values <.001).

Conclusion

Although caregiver-endorsed child sleep problems on surveys did not differ from PCP-documented concerns, there are gaps in documenting other problematic sleep-related health behaviors, such as caffeine consumption and electronics use. More resources to address sleep-related health behaviors, as well as sleep problems, in pediatric primary care are needed.

Support

Sleep Research Society Foundation and K23HD094905 (AAW)

0947 Parent-Perceived Sleep Problems and Sleep Goals in Infants and Toddlers: A Global Sample

Introduction

The aim of this study was to assess parent perceptions of sleep problems in young children and parent-identified areas of change in a global sample.

Methods

Caregivers (95.6% mothers) of 1555 infants/toddlers (birth-37 mos; M=12.2 mos; 49.5% male) completed an online survey, representing Indonesia (n=187), Japan (n=718), New Zealand (n=231), Singapore (n=199), and Thailand (n=221). The survey included an abbreviated version of the Brief Infant Sleep Questionnaire, and a list of potential sleep-related areas of change.

Results

36.9% reported a perceived sleep-problem, whereas 92.9% indicated an area of desired change related to their child’s sleep. In terms of areas of change, 82.5% endorsed bedtime/how child falls asleep, 70.0% nighttime sleep, and 57.8% related to the morning. As expected, 99.7% of parents who endorsed a problem indicated a desired change compared to 88.9% who did not perceive a problem, p < .001. Those who noted a problem were more likely to endorse a change at bedtime (92.5%) and during the night (90.1%), compared to the morning (68.8%). There were country-based differences, with caregivers in New Zealand (47.0%) and Singapore (44.2%) more likely to report a child sleep problem compared to Thailand (35.3%), Japan (34.1%) and Indonesia (29.4%), p < .001. No differences were noted in parent-report of desired change across Japan, New Zealand, Singapore, and Thailand (94-96%) but were significantly higher than Indonesia (83.4%).

Conclusion

Although one-third of parents of young children in a global sample indicate a perceived sleep problem, almost all parents wish to change something about their child’s sleep, primarily relate to bedtime and during the night. Sleep education and assessment delivered by health care providers should focus not only on what families consider to be “problematic,” but also what families would like to modify, or improve, about their child’s sleep within a developmentally appropriate framework.

Support

Johnson & Johnson Consumer Inc., Skillman, NJ, USA.

0946 Parent-Perceived Sleep Problems Associated with Common Medical Issues During Infancy

Introduction

Sleep problems are highly prevalent during infancy. However, little research has been conducted on associations between these sleep issues and common medical concerns in early development. Thus, the purpose of this study was to assess the prevalence of parent-perceived sleep problems in infants with common medical problems.

Methods

Participants were 5,097 children from the Longitudinal Study of Australian Children—Birth Cohort. Caregiver-reported child sleep problems and medical concerns were assessed at ages 0-1 year. Chi-square analyses were used to examine associations between the presence of a parent-perceived sleep problem and medical concerns.

Results

Wheezing (29.6%), eczema (14.9%), and food/digestive allergies (5.0%) were the most commonly identified medical concerns. In addition, 17.1% of caregivers reported a moderate/severe child sleep problem. Infants who had a moderate to severe parent-identified sleep problem experienced higher rates of overall medical care/needs, wheezing, eczema, food/digestive allergies (p<.001), ear infections (p<.05), and other illnesses (p<.01) than those infants without a sleep problem. No differences were observed with regard to hearing problems, vision problems, developmental delay, diarrhea/colitis, anemia, or other (non-ear) infections. Furthermore, parents reported higher rates of sleep problems for infants with medical problems (20.0-37.5%) than for infants without medical problems (16-17%), especially related to needing medical care (sleep problems = 27%), food/digestive allergies (27%), eczema (23%), and wheezing (20%), p=.001.

Conclusion

Overall, common medical issues during infancy, including food/digestive allergies, eczema, and wheezing, are associated with greater parent-endorsed child sleep problems. Primary care providers should assess for and address sleep problems when treating common medical concerns during infancy.

Support

This project was partially supported by Johnson and Johnson Consumer Health (JAM, ESL, and RAG) and NIH K23HD094905 (AAW).

0408 Myths About Infant, Child, and Adolescent Sleep: Addressing False Beliefs That Hinder Sleep Health During These Crucial Developmental Stages

Introduction

Sleep is vital for healthy development from infancy through adolescence. Despite its importance, false beliefs that conflict with scientific evidence (myths) may be common among caregivers and impair sleep health during these crucial stages.

Methods

Researchers compiled a list of potential myth statements using internet searches of popular press and scientific literature. We utilized a Delphi process with experts (n=12) from the fields of pediatric, sleep, and circadian research and clinical practice. Selection and refinement of myths by sleep experts proceeded in three phases, including: focus groups (Phase 1); email-based feedback to edit, add, or remove myths (Phase 2); and closed-ended questionnaires (Phase 3) where experts rated myths on two dimensions: (1) falseness and (2) public health significance using 5-point Likert scale: 1 (“not at all”) to 5 (“extremely false/important”).

Results

Thirty-two sleep myths were identified across three developmental categories: infant (14 myths), child (6 myths), and adolescent (12 myths). Mean expert ratings illuminated the most pressing myths in each developmental category: infant sleep (“Sleep training causes psychological harm, including reduced parent-child attachment:” falseness =4.7, s.d.=0.7; public health significance=4.0, s.d.=1.1); child sleep (“Heavy, loud snoring for my child means he’s sleeping deeply:” falseness=4.8, s.d.=0.6; public health significance=4.7, s.d.=0.7), and teenager sleep (“Falling asleep in class means your teenager is lazy and not motivated:” falseness=4.8, s.d.=0.5; public health significance=4.3, s.d.=0.8).

Conclusion

The current study identified commonly-held myths about infant, child, and adolescent sleep that are not supported by (or worse, counter to) scientific evidence. If unchecked, these myths may hinder sleep at a critical developmental stage. Future research may include public health education to correct myths and promote healthy sleep among infants, children, and teenagers.

Support

5T32HL007901

Nightmares and anxiety in elementary-aged children: is there a relationship

OBJECTIVE

To determine whether a relationship exists between children's anxiety level and nightmare occurrence.

METHOD

A total of 60 kindergarten, second and fourth grade school children and their parents completed questionnaires assessing nightmare occurrence and anxiety.

RESULTS

According to parental report, children who experience nightmares have significantly higher levels of anxiety than children who do not experience nightmares. The results also indicate a relationship between nightmare distress and trait anxiety.

CONCLUSION

These findings suggest that anxiety issues should be considered in children who are experiencing nightmares.

A decade of CLC chloride channels: structure, mechanism, and many unsettled questions

ClC-type chloride channels are ubiquitous throughout the biological world. Expressed in nearly every cell type, these proteins have a host of biological functions. With nine distinct homologues known in eukaryotes, the ClCs represent the only molecularly defined family of chloride channels. ClC channels exhibit features of molecular architecture and gating mechanisms unprecedented in other types of ion channels. They form two-pore homodimers, and their voltage-dependence arises not from charged residues in the protein, but rather via coupling of gating to the movement of chloride ions within the pore. Because the functional characteristics of only a few ClC channels have been studied in detail, we are still learning which properties are general to the whole family. New approaches, including structural analyses, will be crucial to an understanding of ClC architecture and function.

Projection structure of a ClC-type chloride channel at 6.5 A resolution

Virtually all cells in all eukaryotic organisms express ion channels of the ClC type, the only known molecular family of chloride-ion-selective channels. The diversity of ClC channels highlights the multitude and range of functions served by gated chloride-ion conduction in biological membranes, such as controlling electrical excitability in skeletal muscle, maintaining systemic blood pressure, acidifying endosomal compartments, and regulating electrical responses of GABA (gamma-aminobutyric acid)-containing interneurons in the central nervous system. Previously, we expressed and purified a prokaryotic ClC channel homologue. Here we report the formation of two-dimensional crystals of this ClC channel protein reconstituted into phospholipid bilayer membranes. Cryo-electron microscopic analysis of these crystals yields a projection structure at 6.5 A resolution, which shows off-axis water-filled pores within the dimeric channel complex.

Sleep disturbances during pregnancy

OBJECTIVE

To assess sleep patterns and prevalence of sleep disturbances during pregnancy.

DESIGN

Cross-sectional design; prospective questionnaire.

SETTING

Outpatient, private obstetric clinic.

PARTICIPANTS

127 consecutive patients, with women evaluated at one of four points in pregnancy, 8-12 weeks (n = 37), 18-22 weeks (n = 28), 25-28 weeks (n = 24), and 35-38 weeks (n = 38).

MAIN OUTCOME MEASURE

Questionnaire of sleep habits and sleep disturbances.

RESULTS

A large percentage of the women experienced sleep disturbances during pregnancy, These problems included frequent night wakings, difficulty falling asleep, and symptoms of sleep apnea. Few differences in sleep patterns were found across pregnancy, although women were found to sleep more and nap more by the end of pregnancy.

CONCLUSION

Sleep disturbances are common during pregnancy, especially late in pregnancy.

Empirically supported treatments in pediatric psychology: bedtime refusal and night wakings in young children

OBJECTIVE

To review the literature for empirically supported treatments for bedtime refusal and night wakings in young children.

METHODS

An extensive review of the literature resulted in the inclusion of 41 studies that were evaluated according to the criteria established by the Task Force on Promotion and Dissemination of Psychological Procedures (1995).

RESULTS

Evidence exists indicating that extinction and parent education on the prevention of sleep problems can be considered well-established treatments. Furthermore, graduated extinction and scheduled awakenings are probably efficacious treatments, with positive routines a promising intervention.

CONCLUSIONS

A discussion of effectiveness, treatment feasibility, cost-effectiveness, and methodological limitations of the studies is provided. Recommendations for future directions for research in the treatment of these two common sleep disorders are presented.

Developmental features of sleep

In sum, sleep disorders are common problems for children and adolescents, with estimates indicating that approximately 20% to 25% of the pediatric population experiences some type of sleep disturbance. Furthermore, clinicians should be aware that sleep disturbances may not only exist in isolation, but can be related to psychiatric or medical issues. Although much appears to be known about sleep disorders in the pediatric population, our knowledge of this area is still in its infancy. Additional research is still needed to investigate differences in clinical presentation of specific sleep disturbances among different age groups (i.e., children, adolescents, adults, and elderly), to develop the most appropriate treatments for given populations, and to study the effects of sleep disturbances on functioning. Given the prevalence of these problems in the child and adolescent population and its likely impact on cognitive and behavioral functioning, health professionals need to become increasingly aware of and knowledgeable about sleep and sleep disorders. We all spend about one third of our lives sleeping, or trying to sleep; thus, we should understand as much as we can about it.

A practical approach to acute renal failure

Acute renal failure represents a wide variety of renal diseases, which may be challenging to diagnose and even more challenging to treat. As understanding of these diseases improves, so perhaps will clinicians' ability to treat them.

Mutational analysis of the helical hairpin region of diphtheria toxin transmembrane domain

Entry of the catalytic domain of diphtheria toxin into the cytoplasma of eukaryotic cells depends on insertion of the T (transmembrane) domain into the endosomal membrane, a process triggered by low pH. To probe the mechanism of insertion, we mutated ionizable residues within the helical hairpin region of the T domain. Only three mutations caused significant effects on cytotoxicity, D295K, E349K, and D352K. Each of these represents a substitution of a basic for an acidic residue at the tip of a helical hairpin. Substitution of Lys for Glu349 or Asp352, in the TH8/9 hairpin, reduced toxicity for Vero cells > 100-fold, whereas a Lys substitution for Asp295, one of 3 acidic residues in the TH5/6/7 hairpin, caused a less marked reduction. All three mutations also altered the pH-dependent formation, and/or ion conductance, of channels formed by the toxin in artificial bilayers or the plasma membrane. E349K or D352K did not alter the pH dependence of conformational changes in the toxin occurring near pH 5. Our findings support the hypothesis that the TH8/9 hairpin inserts into the endosomal membrane after low pH-mediated partial unfolding of the T domain. A positive residue at the tip of this hairpin apparently inhibits insertion and blocks toxin action. The ion-conducting properties of channels formed by selected mutants, described elsewhere, are consistent with this model. The status of the TH5/6/7 hairpin in the integral membrane form of the T domain remains uncertain.

Pediatricians and sleep disorders: training and practice

OBJECTIVE

A series of studies were conducted to investigate pediatricians' training, knowledge, and practices regarding sleep and sleep disorders in children and adolescents.

METHOD AND RESULTS

Study 1, a national survey of 156 pediatric residency programs, found that pediatricians receive a mean of 4.8 hours of instruction on sleep and sleep disorders, although the mode and median hours of instruction is 0 hours. In study 2, 88 pediatricians completing a questionnaire concerning general knowledge about sleep disorders in children and adolescents received a mean score of 71.8% (range, 40% to 93%). Pediatricians appear to know the most about developmental issues and sleep hygiene and the least about specific disorders such as narcolepsy and parasomnias. In the third study, 183 pediatricians were surveyed about their actual beliefs and practices regarding young children's sleep problems. Together, those surveyed reported that approximately 25% of their patients experience some type of sleep problem. Most pediatricians recommend behavioral interventions, although 14.8% of pediatricians report prescribing pharmacological treatments, and 48.9% inform parents that their child is likely to outgrow the problem.

CONCLUSIONS

The results of these studies support the need for more education in sleep and sleep disorders in children and adolescents within medical schools, pediatric residency programs, and the practicing pediatric community.

Reaction of diphtheria toxin channels with sulfhydryl-specific reagents: observation of chemical reactions at the single molecule level

The diphtheria toxin channel is believed to be a homooligomer of its T domain in which each subunit consists of two alpha-helices, lying within the membrane, connected by a short interhelical loop of four amino acids (residues 349-352). To investigate the validity and implications of this model, we singly mutated each of these amino acids to cysteines, formed channels with the mutant T-domain proteins in planar lipid bilayers, and added to the trans compartment sulfhydryl-specific reagents [methanethiosulfonate derivatives (MTS-ER)] that introduce a positive or negative charge to reacted cysteines. The introduction of a positive charge at residue 351 or 352 (through the MTS-ER reactions) resulted in a step decrease in single-channel conductance, whereas the introduction of a negative charge resulted in a step increase. The opposite sign of these effects indicates the predominantly electrostatic nature of the phenomenon and implies that residues 351 and 352 lie close to the channel entrance. The same reactions at residue 350 resulted in very little change in channel conductance but instead changed the character of the natural rapid flickering of the channel between open and closed states to one in which the channel spent more time in the closed state; this may have resulted from the group introduced at position 350 acting as a tethered channel blocker. The MTS derivatives had no effect on channels containing a cysteine at position 349, suggesting that this residue faces away from the channel entrance. We propose that the step changes in conductance or flickering pattern result from the chemical reaction of one MTS-ER molecule with one cysteine, and thus a bimolecular chemical reaction is being witnessed at the single molecule level. From the distribution of waiting times between the appearance (i.e., the opening) of a channel and the step change in its conductance or flickering pattern, we can calculate a pseudo-first-order rate constant, which can then be converted to a second-order rate constant, for the chemical reaction.

Global social skill ratings: measures of social behavior or physical attractiveness?

Calvert reviewed the literature on social skills and physical attractiveness and concluded that many ratings of social skill may be confounded by the physical attractiveness of the target individual, possibly due to a general perception that physical attractiveness and social competence are positively correlated. In order to examine the influence of physical attractiveness on social skill ratings, Ss made global ratings of social skill and attractiveness for a confederate whose appearance and behavior had been altered to appear attractive or unattractive and socially skilled or unskilled in an assertiveness and heterosocial vignette. The results indicated that the same skilled behavior was viewed as more competent when performed by an attractive person compared to an unattractive person. Attractiveness had no influence on ratings of generally incompetent behavior. Thus, it appears that physical attractiveness does not compensate for poor interpersonal skills, but a skilled, attractive individual may be judged to have particularly good skills. Implications for the assessment of social skills are discussed.

Structure-function relationships in diphtheria toxin channels: I. Determining a minimal channel-forming domain

Diphtheria Toxin (DT) is a 535 amino acid exotoxin, whose active form consists of two polypeptide chains linked by an interchain disulphide bond. DT's N-terminal A fragment kills cells by enzymatically inactivating their protein synthetic machinery; its C-terminal B chain is required for the binding of toxin to sensitive cells and for the translocation of the A fragment into the cytosol. This B fragment, consisting of its N-terminal T domain (amino acids 191-386) and its C-terminal R domain (amino acids 387-535) is responsible for the ion-conducting channels formed by DT in lipid bilayers and cellular plasma membranes. To further delineate the channel-forming region of DT, we studied channels formed by deletion mutants of DT in lipid bilayer membranes under several pH conditions. Channels formed by mutants containing only the T domain (i.e., lacking the A fragment and/or the R domain), as well as those formed by mutants replacing the R domain with Interleukin-2 (IL-2), have single channel conductances and selectivities essentially identical to those of channels formed by wild-type DT. Furthermore, deleting the N-terminal 118 amino acids of the T domain also has minimal effect on the single channel conductance and selectivity of the mutant channels. Together, these data identify a 61 amino acid stretch of the T domain, corresponding to the region which includes alpha-helices TH8 and TH9 in the crystal structure of DT, as the channel-forming region of the toxin.

Structure-function relationships in diphtheria toxin channels: III. Residues which affect the cis pH dependence of channel conductance

The conductance of channels formed by diphtheria toxin (DT) in lipid bilayer membrane depends strongly on pH. We have previously shown that a 61 amino acid region of the protein, denoted TH8-9, is sufficient to form channels having the same pH-dependent conductance properties as those of whole toxin channels. One residue in this region, Aspartate 352, is responsible for all the dependence of single channel conductance on trans pH, whereas another, Glutamate 349, has no effect. Here, we report that of the seven remaining charged residues in the TH8-9 region, mutations altering the charge on H322, H323, H372, and R377 have minimal effects on single channel conductance; mutations of Glutamates 326, 327, or 362, however, significantly affect single channel conductance as well as its dependence on cis pH. Moreover, Glutamate 362 is titratable from both the cis and trans sides of the membrane, suggesting that this residue lies within the channel; it is more accessible, however, to cis than to trans protons. These results are consistent with the membrane-spanning topology previously proposed for the TH8-9 region, and suggest a geometric model for the DT channel.

Structure function relationships in diphtheria toxin channels: II. A residue responsible for the channel's dependence on trans pH

Ion-conducting channels formed in lipid bilayers by diphtheria toxin are highly pH dependent. Among other properties, the channel's single channel conductance and selectivity depend on proton concentrations on either side of the membrane. We have previously shown that a 61 amino acid fragment of DT is sufficient to form a channel having the same pH-dependent single channel properties as that of the intact toxin. This region corresponds to an alpha-helical hairpin in the recently published crystal structure of DT in solution; the hairpin contains two alpha-helices, each long enough to span a membrane, connected by a loop of about nine residues. This paper reports on the single channel effects of mutations which alter the two negatively charged residues in this loop. Changing Glutamate 349 to neutral glutamine or to positive lysine has no effect on the DT channel's single channel conductance or selectivity. In contrast, mutations of Aspartate 352 to neutral asparagine (DT-D352N) or positive lysine (DT-D352K) cause progressive reductions in single channel conductance at pH 5.3 cis/7.2 trans (in 1 M KCl), consistent with this group interacting electrostatically with ions in the channel. The cation selectivity of these mutant channels is also reduced from that of wild-type channels, a direction consistent with residue 352 influencing permeant ions via electrostatic forces. When both sides of the membrane are at pH 4, the conductance difference between wild-type and DT-D352N channels is minimal, suggesting that Asp 352 (in the wild type) is neutral at this pH. Differences observed between wild-type and DT-D352N channels at pH 4.0 cis/7.2 trans (with a high concentration of permeant buffer in the cis compartment) imply that residue 352 is on or near the trans side of the membrane. Comparing the conductances of wild-type and DT-D352K channels at large (cis) positive voltages supports this conclusion. The trans location of position 352 severely constrains the number of possible membrane topologies for this region.

Treatment of childhood sleep disorders: generalization across disorders and effects on family members

Investigated the treatment of bedtime problems and its generalization to night wakings. Six children (M age = 35 months) and their parents participated in this study. A multiple-baseline design across subjects was employed and found that treatment instituted at bedtime was successful in relieving both bedtime disturbances and night wakings. Furthermore, significant positive changes in parental sleep and family satisfaction occurred following amelioration of the children's sleep problems. Data support recent work suggesting that chronic sleep problems in children are amenable to behavioral interventions. In addition, this method appears to be more cost-effective and less stressful for parents to implement than behavioral interventions that directly target night wakings.

Sleep disorders in children

Many children experience some type of sleep problem. Often, these are transient problems with no long-lasting sequelae. But in certain cases, sleep problems may significantly impact on functioning and well-being. Sleep disorders in children can be classified into two major categories. Dyssomnias include those disorders that result in difficulty either initiating or maintaining sleep or involve excessive sleepiness. Parasomnias are disorders that disrupt sleep after it has been initiated but do not result in complaints of insomnia or excessive sleepiness. Even though sleep disorders in children are common, not enough is known. This article reviews the dyssomnias and parasomnias experienced by children, discusses methodological limitations of the studies reviewed, and presents future directions for research in this field.

Structure/function analysis of the transmembrane domain of DAB389-interleukin-2, an interleukin-2 receptor-targeted fusion toxin. The amphipathic helical region of the transmembrane domain is essential for the efficient delivery of the catalytic domain to the cytosol of target cells

Cassette and deletion mutagenesis were used to analyze the function of the amphipathic alpha-helices in the transmembrane domain of DAB389-interleukin-2 (IL-2), a fusion protein which is targeted to the interleukin-2 receptor. We demonstrate that the in-frame deletion of 60 amino acids, from Asn204 to Glu263 in DAB389-IL-2, results in complete loss of cytotoxic activity, whereas when the amphipathic regions from Asp208 to Ser220 and Ala244 to His258 are replaced with idealized amphipathic helices composed of repeating Glu, Lys, and Leu residues, the mutant fusion toxin has low but detectable activity. DAB389-IL-2 and both variants form channels in artificial phospholipid bilayers with conductances identical to those formed by diphtheria toxin. Both mutant fusion toxins bind to the high affinity IL-2 receptor with affinities similar to that of DAB389-IL-2. The fact that these mutants have markedly reduced or absent cytotoxic activity, but possess "wild type" catalytic activity, binding affinities, and channel conductances, suggests the existence of a step in the intoxication pathway, defective in the mutants, which occurs after DAB389-IL-2 binds to the IL-2 receptor. It is unknown whether this step occurs prior or subsequent to channel formation, but it is essential for the efficient delivery of the ADP-ribosyltransferase from DAB389-IL-2 to the cytosol of target cells.

Sleep disorders in children

Many children experience some type of sleep problem. Often, these are transient problems with no long-lasting sequelae. But in certain cases, sleep problems may significantly impact on functioning and well-being. Sleep disorders in children can be classified into two major categories. Dyssomnias include those disorders that result in difficulty either initiating or maintaining sleep or involve excessive sleepiness. Parasomnias are disorders that disrupt sleep after it has been initiated but do not result in complaints of insomnia or excessive sleepiness. Even though sleep disorders in children are common, not enough is known. This article reviews the dyssomnias and parasomnias experienced by children, discusses methodological limitations of the studies reviewed, and presents future directions for research in this field.

Locating a residue in the diphtheria toxin channel

We are studying structure-function relationships in the Diphtheria Toxin (DT) channel using a combination of site-directed mutagenesis and electrophysiology in artificial lipid bilayers. We made site-directed mutations of charged residues in the toxin's channel-forming B fragment, and after expressing the mutant proteins in Escherichia coli, we analyzed the single channels they formed in lipid bilayers. Changing aspartate 352, which is located in a short hydrophilic loop separating two hydrophobic stretches, to asparagine or lysine dramatically reduces the single-channel conductance of the pore at pH 5.3 cis, 7.2 trans (5.3/7.2). Lowering the pH on both sides of the membrane essentially eliminates the difference between wild-type and D352N; this finding is consistent with the idea that an aspartate with a (protonated) neutral side-chain and the always neutral asparagine have similar electrostatic influences on permeant ions. Using a high concentration of permeant buffer to clamp the pH of the cis compartment and the pore, and varying the pH on the trans side, we have located D352 at or near the trans compartment. We further find that D352N channels, in contrast to wild-type, display conductances independent of trans pH. This observation allows us to determine the titration curve of aspartate 352 in the wild-type toxin, establishing its pKa at approximately 5.5.

Behavioral treatment of multiple childhood sleep disorders. Effects on child and family

Sleep disorders are highly prevalent among otherwise healthy young children and can be extremely disruptive to family life. Treatment was initiated in a multiple baseline fashion for the chronic night waking and nighttime disturbance exhibited by a 14-month-old girl. We found that "graduated extinction" (gradually increasing the time before attending to the child's crying) resulted in rapid reductions in these sleep disorders. Additionally, data on parental depression and marital satisfaction showed general improvement as a function of improved child sleep patterns. These results are discussed as they relate to the treatment of common childhood behavior disorders and their role in family satisfaction.