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Biomedical subjects

L Lewin

Publications and source records attributed to L Lewin.

At least 19 recordsLinked to original sources
PubMed2001

Attachment behaviors, depression, and anxiety in nonoffending mothers of child sexual abuse victims.

The purpose of this study was to examine the psychological well-being and attachment behavior of nonoffending mothers of child sexual abuse victims (CSAVs). This topic is significant because it is the mothers who most often provide support for young child victims. Two sets of data on maternal depression, state and trait anxiety, and Ainsworth's maternal attachment behaviors were analyzed. First, 38 mothers of CSAVs were compared based on the presence or absence of maternal history of abuse. Second, from the original 38 mothers of CSAVs, 27 mothers were compared to a matched group of mothers of nonabused children. Children in both data sets were 6 to 48 months. In the first data set, there were no significant differences in depression, anxiety, and attachment behaviors based on mothers' personal history of abuse. However, in the second data set, mothers of CSAVs had heightened levels of depression and anxiety and diminished maternal attachment behaviors.

Adolescent↗
PubMed1996

Differences in the release of L-glutamate and D-aspartate from primary neuronal chick cultures.

Primary neuronal cultures were made from eight-day-old embryonic chick telencephalon. Ten-day-old cultures were used to study the release of D-[3H]aspartate and L-[3H]glutamate. The D[3H]aspartate release was stimulated by increasing potassium concentrations, but it was not calcium dependent. In contrast, the potassium dependent L-[3H]glutamate release was calcium dependent, and furthermore L-[3H]glutamate release was optimal at potassium concentrations < 30 mM. The inhibitors of glutamate uptake, dihydrokainate and 1-aminocyclobutane-trans-1,3-dicarboxylic acid (CACB), also referred to as cis-1 -aminocyclobutane-1,3-dicarboxylate, were used in the release experiments. Dihydrokainate had no effect on aspartate release, whereas CACB increased both the basal efflux of D-[3H]aspartate and the potassium evoked release. CACB had no effect on the potassium stimulated L-glutamate release. We believe that L-glutamate is released mainly by a vesicular mechanism from the presumably glutamatergic neurons present in our culture. D-aspartate release observed by us, could be mediated by a transporter protein. The cellular origin of this release remains to be assessed.

Animals↗
PubMed1996

What is driving health system change?

Socially amoral economic forces now drive health system change. The authors, assisted by a panel of experts on employers, health plans, providers, and consumers, discuss current drivers such as (1) employers' price-focused purchasing, without good quality/value measures; (2) health plans' growing successes and market clout; (3) providers declining prospects and fears about their future; and (4) consumers' worries about less choice. Future influences will include Medicare reforms, better information, and pro-consumer regulation of managed care, as well as rising social distress. The health system's future is now open for resolution in an evolving, imperfect market.

Choice Behavior↗
PubMed1995

Interviewing the young child sexual abuse victim.

1. Nurses can facilitate the disclosure by a young child of sexual abuse by using developmentally sensitive language, such as through the use of proper nouns, single-idea sentences, and the avoidance of technical terms. 2. Nurses can guide the interview from benign, open-ended questions to context-specific, focused questions. Differentiation is made between being specific versus being suggestive. 3. Rapport-building is an important part of the alliance with the child and the nurse. Interviewers should be matter-of-fact and acknowledge any discomfort the child may demonstrate. 4. Cognitive interviewing is a specific technique designed to access accurate recall of a child's memories through reconstruction and memory-jogging techniques.

Age Factors↗
PubMed1994

Net taurine transport and its inhibition by a taurine antagonist.

P2-fractions were isolated from rat brain, and used to study net taurine transport. The fractions were incubated in increasing concentrations of [3H]taurine and the intraterminal concentration measured by liquid scintillation and amino acid analysis. The membrane potential of the isolated fractions was estimated using 86Rb+ as a marker for intracellular K+. Taurine was synthesized in the P2-fraction when incubated in taurine free medium. At external taurine concentrations below 370 microM a significant amount of the endogenous taurine was released to the incubation medium. Net taurine uptake into the P2-fraction was achieved at external taurine concentrations exceeding 370 microM. The taurine antagonist 6-aminomethyl-3-methyl-4H, 1, 2, 4-benzothiadiazine-1, 1-dioxide (TAG) competitively inhibited taurine and [3H]taurine transport into the P2-fraction. As the external concentration of taurine was increased, the accumulation of 86Rb+ into the P2-fraction was facilitated. This indicated an increasing hyperpolarization of the neuronal membrane as taurine transport shifted from release towards uptake. TAG reduced the hyperpolarization that paralleled taurine accumulation, in a dose dependent manner. Our results indicate that relatively low transmembranal gradients of taurine may be maintained by an electrogenic taurine transporter having a large transport capacity. Such a transporter may well serve the needs of osmotic regulation, i.e. to transport large amounts of taurine in any direction across the neuronal membrane.

Animals↗
PubMed1994

Inhibition of SKF 89976-A of the gamma-aminobutyric acid release from primary neuronal chick cultures.

Neuronal cultures were made from the 8-d-old embryonic chick telencephalon. The primary culture model was further improved, the medium composition was modified, and the cells grown for 10 d, which allowed the development of relatively differentiated neurones. A superfusion protocol was developed and applied to study the release of [3H]-gamma-aminobutyric acid ([3H]GABA). High endogenous activity levels of glutamate decarboxylase (GAD) and of a Ca-dependent potassium stimulated [3H]GABA release were used as criteria for GABAergic differentiation. The influence of the non-substrate inhibitor of GABA transport, SKF 89976-A, on the GABA release, was studied using the primary neuronal culture. The release was found to be inhibited by SKF 89976-A at higher concentrations (= 400 microM).

Analysis of Variance↗
PubMed1994

Child abuse: ethical and legal concerns for the nurse.

1. Nurses, as well as many other types of professionals, are required by law to report any incidence or evidence of child abuse or neglect. The nurse or other professional is immune from liability after reporting an incidence of child abuse, but the nurse can be held civilly and criminally liable if he or she fails to make a report of suspected abuse. 2. Nurses are permitted, by law, to enter evidence and testify on behalf of the victim, especially if it is deemed to be too harmful or traumatic for the child to endure. 3. Nurses can aid greatly in the prosecutorial process by utilizing their relationship with the victim to ease the often-daunting pressure of the courtroom and the difficulty in dealing with and recounting the abusive incidents.

Child↗
PubMed1992

Inhibition of transporter mediated gamma-aminobutyric acid (GABA) release by SKF 89976-A, a GABA uptake inhibitor, studied in a primary neuronal culture from chicken.

The effect of SKF 89976-A, a lipophilic non-substrate inhibitor of the gamma-aminobutyric acid (GABA) transporter, on the release of radioactive GABA and D-aspartate has been studied. Neuronal cultures from 8 day old chick embryos, grown for six days, served as a model. The cultures were incubated with [3H] D-aspartate and [14C] GABA with the subsequent addition of high or low concentrations of SKF 89976-A. Finally the cultures were exposed to differently composed media for either 30 or 300 seconds. The release was quantified, using liquid scintillation counting. The efflux of [3H] D-aspartate and [14C] GABA was increased by [K+] and time, and a minimum value was obtained at [Ca2+] 1.05 mM. The release of both [3H] D-aspartate and [14C] GABA was inhibited by SKF 89976-A. The obtained results indicate that transporter mediated processes are the major mechanisms of transmitter release in the investigated model.

Animals↗
PubMed1992

On the activity of gamma-aminobutyric acid and glutamate transporters in chick embryonic neurons and rat synaptosomes.

The uptake of radioactive gamma-aminobutyric acid (GABA) and D-aspartate and the effect of SKF 89976-A, a non-substrate inhibitor of the GABA transporter, on this uptake have been investigated. Neuronal cultures from eight-day-old chick embryos grown for three or six days in vitro, were used as a model. For comparison, we also used the P2-fraction from rat. Neuronal cultures grown for three and six days expressed high-affinity uptake systems for [3H]GABA and for D-[3H]aspartate with an increasing Vmax during this period. The lipophilic non-substrate GABA uptake inhibitor, SKF 89976-A, inhibited transporter mediated uptake of GABA both in cell cultures from chicken, and in P2-fractions from rat. The results also showed that SKF 89976-A was a poor inhibitor of the uptake of D-aspartate. We found no non-saturable uptake of D-aspartate.

Amino Acid Transport System X-AG↗
PubMed1974

Preference for signalled reinforcement.

Key pecking was reinforced on a two-component multiple schedule. A variable-interval schedule controlled reinforcement in both components. During one component, access to reinforcement was preceded by a tone; in the other component, a standard unsignalled schedule was in effect. After performance stabilized, subjects were given a choice between the signalled and unsignalled schedules. They were placed in the chamber with the unsignalled schedule in effect on the right key. A single response on the left, or changeover, key produced the signalled schedule for 1 min. Both pigeons in Experiment I pecked the changeover key at a rate sufficient to remain under the signalled schedule for over 90% of the session. Removing and reintroducing the tone demonstrated that the changeover-key responses were due to the occurrence of the tone. In Experiment II, when pecking the changeover key produced the unsignalled schedule, pecking the changeover key declined. The results may be explained either in terms of Hendry's information hypothesis or as escape from an intermittent positive reinforcement schedule.

Journal Article↗
PubMed1974

Negatively reinforced key pecking.

A reinforcement-switching procedure was used to produce negatively reinforced key pecking in pigeons. First, key pecking on a chain schedule (fixed-interval 10-sec variable-interval 60-sec) was conditioned using grain reinforcement. Second, intermittent shock in the initial link was introduced at a low intensity and gradually increased. Third, food reinforcement in the terminal link was eliminated. With shock at 90 V occurring on the average every 3 sec, initial-link pecking was maintained with no terminal-link food. Three of four pigeons responded consistently at shock intensities of 90, 70, and 50 V but not at 30 V. A fourth pigeon responded at but not below 90 V. Rate of response was directly related to shock frequency. Eliminating food deprivation did not affect the negatively reinforced performance.

Journal Article↗
PubMed1971

Down on the Bayou.

Explore the source record for details and available documents.

Black or African American↗
PubMedDate not supplied

Screening families with young children for child maltreatment potential.

The incidence of child maltreatment in the United States is increasing. According to the third National Incidence Study of Child Abuse and Neglect (NIS-3), the number of abused and neglected children doubled between the years 1986 and 1993 to 2.8 million (Sedlak & Broadhurst, 1996). This same study found that the number of children who were seriously injured quadrupled during this period of time to nearly 570,000. Conservative estimates suggest that 10% to 20% of children under 12 years of age experience physical or sexual abuse or neglect. In over 80% of these circumstances, the perpetrator is a family member. Risk indicators have been identified that significantly increase the likelihood of abuse or neglect of children. Interventions that reduce these risk factors have been found to be associated with a decreased incidence of abuse and neglect (Andrews, 1994; Barber-Madden, Cohn, & Scholesser, 1988; Garbarino, 1986; Helfer, 1987). However, existing risk assessment or intervention guides for use with families of children under the age of 3 years are not concise enough for use in a busy primary care setting. For this reason, the Parenting Maltreatment Risk and Intervention Protocol was designed to aid in the identification of families with children under the age of 3 who are at risk for child abuse and neglect and to guide initial intervention, referral, and follow-up care.

Child↗
PubMedDate not supplied

Establishing a therapeutic relationship with an abused child.

Establishing a therapeutic relationship with a child who has been abused is a challenge for the pediatric nurse. The relationship progresses from free play to specific interchange focused on disclosure of the abuse. The nurse needs to be cognizant of language and setting that is developmentally compatible with the child and directs interventions that help to empower the child to resolve his or her vulnerability.

Child↗