Do Attachment, Educator Characteristics and Youth-Educator Relationship Matter in 6-Month Changes of Institutionalized Adolescents?

OBJECTIVE: This longitudinal study involved youths in residential care due to previous adverse experiences and their educators, aiming to investigate the role of youths and educators' attachment, educators' psychopathology, and the quality of youth-educator relationship on change scores of youths' symptoms and youth-educator relationship security over 6 months. METHOD: Participants were 36 institutionalized youths (Mage = 16.50 ± 2.13) and their 25 main educators (Mage = 38.48 ± 5.75), assessed at baseline (T1) and 6 months later (T2). Youths were assessed in total, internalizing and externalizing problems via a multi-informant approach, and educators in psychopathology levels. Attachment representations of youths and educators were assessed through validated attachment interviews (Friends and Family Interview and Adult Attachment Interview), and both separately rated the youth-educator relationship. RESULTS: (1) Most cases remain stable over 6 months. (2) Educator narrative coherence and the quality of youth-educator relationship at baseline were correlated but not predictive of change in youths' symptoms. (3) Youths' higher attachment disorganization at baseline was the unique predictor of 14% variance of positive change in the youth-educator relationship security perceived by the youth. (4) Youth attachment avoidance uniquely predicted 37% of positive change variance in the youth-educator relationship security perceived by educators. CONCLUSION: In conclusion, attachment-based assessment of youths and educators can inform intervention to foster youth improvement.

Continuity and discontinuity of attachment patterns: a short-term longitudinal pilot study using a sample of late-adopted children and their adoptive mothers.

This study analysed the attachment patterns of 28 late-adopted children (placed when they were between four and seven years of age) and their adoptive mothers. The change in the children's internal working models (IWMs) within seven to eight months of their placement was evaluated. In addition, we wanted to observe the influence of a secure-autonomous maternal state of mind in facilitating the change in the children's IWMs and the possible associations between the maternal IWMs and the children's IWMs in the adoptive dyads. The separation-reunion procedure (SRP) was used for the late-adopted children in order to assess their attachment behavioural patterns, and the Manchester Child Attachment Story Task (MCAST) was used to evaluate their attachment narrative patterns. The adoptive mothers completed the Adult Attachment Interview (AAI) in order to classify their state of mind with regard to attachment. The results showed a significant change in the attachment behavioural patterns of late-adopted children, from insecure to secure (p = .002). Furthermore, the children who presented this change were predominantly placed with secure-autonomous adoptive mothers (p = .047), although the link between the adoptive mothers' representations of their attachment history and their adopted children's completed narratives was not significant. In conclusion, it seems possible to revise the attachment behaviour of late-adopted children but, for about one-third of children, the adverse history will persist at a narrative/representational level.

'Adoption and attachment theory' the attachment models of adoptive mothers and the revision of attachment patterns of their late-adopted children.

OBJECTIVE: This study examined the attachment patterns of late-adopted children (aged 4-7) and their adoptive mothers during the first 7- to 8-month period after adoption and aimed to evaluate the effect of adoptive mothers' attachment security on the revision of the attachment patterns of their late-adopted children. DESIGN: We assessed attachment patterns in 20 adoptive dyads and 12 genetically related dyads at two different times: T1 (time 1) within 2 months of adoption and T2 (time 2) 6 months after T1. METHODS: The children's behavioural attachment patterns were assessed using the Separation-Reunion Procedure and the children's representational (verbal) attachment patterns using the Manchester Child Attachment Story Task. The attachment models of the adoptive mothers were classified using the Adult Attachment Interview. RESULTS: We found that there was a significant enhancement of the late-adopted children's attachment security across the time period considered (P= 0.008). Moreover, all the late-adopted children who showed a change from insecurity to security had adoptive mothers with secure attachment models (P= 0.044). However, the matching between maternal attachment models and late-adopted children's attachment patterns (behaviours and representations) was not significant. CONCLUSIONS: Our data suggest that revision of the attachment patterns in the late-adopted children is possible but gradual, and that the adoptive mothers' attachment security makes it more likely to occur.

ATP dependence of H+ secretion.

Cells in isolated rabbit gastric gland were made permeable to ATP by high voltage discharge across a gland suspension. In both normal (5.4 mM K+) and high K+ (108 mM) medium, this electrical shock resulted in a marked reduction in the ability of the parietal cell to produce and accumulate acid. Acid production was monitored both microscopically by acridine orange accumulation in the secretory canaliculus and by accumulation of the weak base [14C]aminopyrine. In 108 mM K+ solutions but not in 5.4 mM K+ solutions 5, mM ATP was able to restore the accumulation of these probes to control (unshocked) levels. When shocked glands had been previously stimulated by secretagogues, the aminopyrine accumulation ratio was only partly restored by ATP. Inhibition of mitochondrial respiration by cyanide, azide, or Amytal abolished acid secretion; the subsequent addition of ATP to shocked glands increased the aminopyrine accumulation ratio to 47 and resulted in an acridine orange fluorescence indistinguishable from that of histamine-stimulated, unshocked glands. We conclude that ATP can act as a substrate for H+ secretion in the parietal cell, and that perhaps no additional energy source is necessary.

The differential effect of thyrotropin on the electrical responses of thyroid cells in monolayer cultures of varying duration.

The acute effects of thyrotropin on the membrane potential of thyroid cells maintained in the presence or absence of thyrotropin (0.2 U/ml) in the culture medium was determined. Monolayer cultures were prepared from porcine thyroid glands and cultured for 4--17 days after which the culture medium was exchanged for a buffered salt solution for intracellular measurements of the membrane potential. Cells were serially impaled with a microelectrode, first in the absence and then in the presence of 10 mU/ml thyrotropin. Cells cultured for 4--9 days depolarized from --29.6 +/- 1.7 (mean +/- S.E.) to --19.3 +/- 1.3 mV within 10 min after acute addition of 10 mU/ml thyrotropin. From 11 to 17 days of culture, basal membrane potentials were lower and, in most instances, cell hyperpolarization occurred within 30 min in response to thyrotropin. There was no difference in the electrical response of cells maintained in culture with or without thyrotropin. However, cells cultured with thyrotropin formed follicle-like structures in contrast to the monolayer formation of cells cultured without thyrotropin. The changes in the basal and stimulated electrical responses occur within a time frame similar to that reported for changes in the biosynthetic capacity of thyroid cells in culture. The data further emphasize the possible regulatory role of the cell membrane in stimulus-secretion coupling in the thyroid.

Electrophysiological evidence for the autoregulation of beta-cell secretion by insulin.

Electrophysiological studies of cultured rat pancreatic beta-cells using intracellular microelectrodes show that exogenous insulin over the range of 0.1 -- 10.0 microng/ml inhibits the electrical activity due to 27.8 mM glucose in a dose-related manner. This inhibitory effect is manifested by a mean increase of the membrane potential from about --20 to --30 mV and inhibition of the number of cells impaled showing spike activity from 60 to less than 10%. The inhibitory influence of insulin is rapid occurring within 5 min for the highest level used. The results provide evidence for a negative feedback role of insulin in regulating its own release.

Substrate requirements for the phosphoinositide response in rat pancreatic islets.

The relationship between phosphatidylinositol hydrolysis and the first phase of insulin secretion has been investigated by briefly exposing rat pancreatic islets that had been prelabelled with myo-[2-3H]inositol to various agonists and antagonists of insulin secretion. The recovery of lipid-bound radioactivity progressively decreased as the D-glucose concentration of the incubation medium was increased. Those carbohydrates that stimulated insulin secretion evoked a phosphoinositide response, whereas non-stimulatory carbohydrates did not. With the notable exception of amino acids, non-carbohydrate secretagogues were also found to decrease the islet lipid-bound radioactivity. Inhibition of islet glucose metabolism was found to decrease the recovery of lipid-bound radioactivity, largely as a result of impaired de novo phosphoinositide synthesis. The phosphoinositide response to glucose was not affected by inhibition of microtubular function, but was dependent upon the availability of extracellular calcium ions. We conclude that the phosphoinositide response in carbohydrate-stimulated islets is not directly related to the activation of membrane-associated glucose receptors, but may occur as a consequence of the subsequent transmembrane movement of calcium ions. Finally, the observation that stimulatory amino acids did not evoke a phosphoinositide response suggests that, under certain circumstances, this phenomenon can be dissociated from insulin secretion.

Modification of glucose-induced insulin release by alteration of pH.

Protons (H+) generated by glucose metabolism have been proposed to serve as a coupling factor between cationic and secretory events in the B-cell. We have examined the influence of alteration of extracellular or intracellular pH (pHo or pHi) on dynamic secretory responses of perfused rat islets to 4.2, 8.4, or 16.7 mM glucose. Reduction of pHo from 7.4 to 7.0 inhibited the secretory response to 16.7, but not 8.4 mM glucose, by 47% during the 30-min period following medium change. Increase of pHo from 7.4 to 7.8 had no influence on the secretory response to glucose. Alteration of pHo had no influence on basal insulin release in the presence of 4.2 mM glucose. Sulfamerazine (5 mM), a permeable weak acid, augmented the secretory response to 8.4 mM glucose by 60% but had no influence on the response to 16.7 mM glucose. In contrast, imidazole (10 mM), a permeable weak base, inhibited the secretory response to both 8.4 (62%) and 16.7 mM (72%) glucose. Another weak base, NH4Cl (20 mM), also inhibited the secretory response to 8.4 (61%) and 16.7 mM (68%) glucose. Alteration of pHi by sulfamerazine and imidazole did not alter basal insulin release in the presence of 4.2 mM glucose. A comparison of the present findings to those obtained for the influence of pH on glucose-induced electrical activity indicates that alteration of pHi, and not pHo, induces parallel effects on glucose-induced electrical and secretory events.

Influence on anion transport on glucose-induced electrical activity in the B-cell.

We have previously shown that the effect of glucose on electrical activity (EA) in islet B-cells is altered by modification of pH. The regulation of intracellular pH (pHi) in nerve and muscle cells is coupled to anion exchange. In the present study we have examined the involvement of HCO3:Cl exchange across the plasma membrane in the maintenance of glucose-induced EA in B-cells. 4,4'-diisothiocyanostilbene-2,2' disulfonic acid (DIDS), an inhibitor of anion exchange, elicited a dose-related stimulation of EA in the presence of 11.1 mM glucose. The increase in the relative duration of the active phase (constant spike activity) was first observed at 20 microM DIDS, and a nearly maximal effect was obtained at 200 microM. The substitution of HCO3- by a Hepes buffer elicited constant spike activity. The application of 0.25 microM tributyltin, an electroneutral Cl:OH exchanger, also enhanced EA as indicated by an increase in the duration of the active phase. The influence of HCO3- withdrawal, DIDS, and tributyltin all elicited electrical events similar to that obtained by a decrease in pHi. Our results suggest that anion exchange may be involved in the regulation of electrical events in the B-cell by influencing pHi, as has been documented to occur in invertebrate nerve and muscle.

Somatostatin: mechanism of action in pancreatic islet beta-cells.

The widespread role of somatostatin (SRIF) as a mediator of function in the brain and gut has stimulated interest in it mechanism of action. We have examined the mode of action of SRIF in stimulus-secretion coupling in the pancreatic islet beta-cell to determine whether SRIF antagonizes the glucose-induced decrease in K+ permeability (PK). The influence of SRIF on 86Rb fluxes and insulin release in cultured rat islet cells, and also the electrical events recorded from cultured islets and microdissected mouse islets, was examined. In cultured islets, 100 ng/ml SRIF in the presence of 16.7 mM glucose inhibited the incidence of spike activity and evoked hyperpolarization. This effect was counteracted by 0.1 mM quinine and 20 mM tetraethylammonium (TEA), drugs that inhibit the Ca2+-sensitive or voltage-sensitive increase in PK, respectively. These agents also counteracted the inhibitory influence of SRIF on glucose-induced insulin release in cultured islets. SRIF disrupted the typical glucose-induced oscillatory pattern of electrical activity (burst activity) during continuous microelectrode recordings in mouse beta-cells, resulting in a transient 5mV hyperpolarization and a decrease in the frequency of generation of burst activity. The presence of 20 mm TEA prevented the influence of SRIF on the electrical activity. SRIF had no effect on the accumulation of 86Rb into islet cells obtained in the presence of 16.7 mM glucose. However, SRIF enhanced the rate of 86Rb efflux from cells exposed to glucose. SRIF-induced enhancement of 86Rb efflux was antagonized by TEA or quinine. These results indicate that SRIF may activate PK as its primary mode of action, an event that may be sufficient to reduce the accumulation of intracellular Ca2+ thereby disrupting glucose-induced stimulus-secretion coupling.

Endogenous prostaglandin synthesis and glucose-induced insulin secretion from the adult rat pancreatic islet.

Although exogenous prostaglandins are recognized modulators of insulin secretion, the relationship between their endogenous synthesis and insulin secretion has not been rigorously studied in isolated adult rat islets. Using 3H-arachidonic acid as a tracer, we evaluated the effect of glucose stimulation upon the incorporation of this fatty acid into islet phospholipids and prostaglandins (separated by extraction and sequential silicic acid, thin-layer and paper chromatography). We observed that 3H-arachidonic acid was incorporated into islet phospholipids and prostaglandins under basal conditions (0.3 mg/ml glucose). Furthermore, exposure of islets to a stimulatory glucose concentration led to significant increases in the recovery of 3H-arachidonic acid-derived radioactivity in islet phosphatidylethanolamine, phosphatidylserine, sphingomyelin, and phosphatidylinositol as well as into all of the measured prostaglandins (A2, B2, D2, E2, and F2 alpha). The most marked increases in recovered radioactivity resulting from a stimulatory glucose concentration were in islet phosphatidylethanolamine and prostaglandin A2 (which we believe to be derived, in large part, from endogenously synthesized prostaglandin E2). These glucose-induced increases in 3H-arachidonic acid-derived radioactivity in both the phospholipid and the prostaglandin fractions were eliminated by the inhibition of phospholipase A2 activity with mepacrine or by the inhibition of cyclooxygenase activity with sodium salicylate. When islets prelabeled with 3H-arachidonic acid were exposed to a high glucose concentration in a perifusion system, there was a brisk extracellular release of radioactivity (presumably representing unidentified prostaglandins) that began within 1 min and that peaked slightly before the peak of the first phase of insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrical and secretory manifestations of glucose and amino acid interactions in rat pancreatic islets.

Interactions between glucose and amino acids in rat pancreatic islets were studied by recording the intracellular membrane potential and spike discharges from the isolated perfused pancreas. It was found that L-isoleucine requires the presence of basal glucose (5 mM) in order to increase spike discharge from islet cells and depolarize the cell membrane. Similarly basal glucose is needed for insulin release by L-isoleucine. A physilolgical mixture of twenty amino acids also required the presence of basal glucose in order to increase spike activity and insulin release. In contrast to L-isoleucine the amino acid mixture did not depolarize the beta-cells. Iodoacetate, at concentrations previously shown to block glycolysis completely, did not interfere with any of these permissive actions of glucose, nor did iodoacetate alter the well known electrical manifestations of high levels of glucose itself (i.e. depolarization and increased spike discharge). These data show that glucose plays a pre-eminent role as regulator of islet cell function, governing the efficacy of amino acids as beta-cells stimulants. The results are most easily interpreted if one assumes that glycolysis is not required for glucose to exert its action.

Multiple metabolic functions of glucose in rat pancreatic islets.

Metabolic interactions between glucose and amino acids were studied with isolated rat islets using glucose utilization and lactate formation as indicators. Certain amino acids (8-10 mM) are capable of greatly stimulating lactate formation from 5mM glucose. On a molar basis L-isoleucine is the most potent stimulator in a group of twenty-six amino acids. Aphysiological amino acid mixture (7.5-14 mM) or L-isoleucine (8 mM) profoundly altered the basic sigmoidal relation between glucose concentration in the medium and the rate of glucose utilization and lactate formation: with basal glucose (5 mM) both glucose utilization and lactate production were stimulated by the amino ACID MIXTURE and by L-isoleucine; at high glucose levels utilization was decreased by the amino acid mixture, but was unaffected by L-isoleucine, whereas lactate formation was decreased by both additions. The data indicate that amino acids may play a significant role in regulating the extent to which glucose serves as a fuel of pancreatic islet cells and in determining the pathways of glucose metabolism. In order to elucidate the mechanisms of the amino acid effect, studies with phloridzin, ouabain, iodoacetate, cytochalasin B, and Na+-deficiency were performed with the most effective amino acid, L-isoleucine. Each of these agents and Na+-deficiency substantially reduced or completely blocked the extra lactate formation induced by L-isoleucine (8-10 mM). The intracellular uptake of 14-CL-isoleucine by isolated islets was found to be Na+-independent, and uphill transport of this amino acid was not detectable, whether basal glucose was present in the medium or not. The action of iodoacetate in blocking glycolysis was reinvestigated. After forty-five minutes of exposure, 0.2mM iodoacetate completely blocks lactate formation as well as glucose utilization. Thisconfirms and extends earlier data for this laboratory and suggests that this SH-reagent indeed allows dissociation of the fuel and releasing functions of glucose.

Phospholipase C and melittin enhancement of glucose-induced electrical activity.

The influence of exogenous phospholipase C and melittin on electrical activity in islet B cells was determined to assess the extent to which polyphosphatidylinositol turnover serves to generate components that influence the electrical events in the plasma membrane. Phospholipase C hydrolyzes polyphosphatidylinositol to diacylglycerol and polyphosphoinositol, whereas melittin increases the susceptibility of phospholipids to phospholipases and increases the permeability of the membrane to ions. Application of both 20 mU/ml phospholipase C or 0.5 mg/ml melittin to 11.1 mM glucose elicited a time-dependent enhancement of glucose-induced electrical activity that stabilized after 10 min. Phospholipase C increased both the active phase fraction and the burst frequency, whereas melittin only increased the burst frequency. These results indicate that both compounds, which disrupt the phospholipid environment of the plasma membrane, play a role in modulating the oscillatory pattern of electrical activity in the B cell, although melittin is obviously not influencing the factors controlling the ionic events in the same manner as phospholipase C.

The role of chemiosmotic lysis in the exocytotic release of insulin.

The role of chemiosmotic lysis in the exocytotic release of insulin has been studied using perifused rat pancreatic islets of Langerhans. Established criteria for osmotic lysis of secretory granules requires proton translocation across the secretory granule membrane and the influx of a permeant anion. The consequent increase in granule osmolarity induces water entry and granule lysis. A proton gradient has been previously established to exist across the insulin secretory granule membrane. We have examined the sensitivity of insulin release to 1) hyperosmolar solutions, 2) replacement of medium Cl-, 3) replacement of medium Na+, and 4) anion transport inhibitors. The addition of 200-600 mM sucrose resulted in a 32-69% inhibition of insulin release due to 16.7 mM glucose. Replacement of Cl- by isethionate or SO4--reversibly inhibited glucose-induced insulin release by 47% and 78%, respectively. Na+ replacement by choline did not influence the secretory response. 4,4'-Diisothiocyano-2,2'-stilbene disulfonic acid (500 microM) and probenecid (10 mM) inhibited insulin release by 73% and 79%, respectively. These drugs are known to inhibit anion exchange in erythrocytes and may be influencing Cl- entry into the secretory granule fused to the plasma membrane by a similar mechanism. Furosemide inhibits NaKCl2 cotransport in erythrocytes, but had no influence on glucose-induced insulin release, suggesting that Cl- does not enter the secretory granule by this pathway. The primary criteria for the participation of a chemiosmotic mechanism subserving lysis of the insulin secretory granule are fulfilled by these results.

Effect of substitution of a permeable weak acid for the permissive role of glucose in amino acid-induced electrical activity in B-cells.

The amino acids L-leucine, L-isoleucine, and L-arginine require a subthreshold concentration of glucose to elicit insulin release and electrical activity from B-cells. There is evidence suggesting that protons couple the metabolism of glucose to the functional response of B-cells. In view of this, a permeable weak acid, sulfamerazine, was used to determine if the generation of intracellular protons could account for the permissive action of glucose. Addition of 10 mM sulfamerazine elicited constant spike activity only with 20 mM leucine. With 20 mM arginine or isoleucine, sulfamerazine induced silent depolarization no different from that caused by sulfamerazine alone. The pattern of the electrical activity of each amino acid plus 5.6 mM glucose or alpha-ketoisocaproic acid alone was qualitatively different; addition of sulfamerazine enhanced the electrical response. The permeable weak base NH4Cl at 20 mM immediately inhibited the electrical response to each amino acid plus glucose or alpha-ketoisocaproic acid alone. The effects of the permeable weak acid and base indicate that intracellular pH is important in maintaining amino acid-induced electrical activity. The permissive role of glucose may be due to provision of protons only with leucine.

Electrical responses of rat islets maintained in culture with varying levels of glucose.

The electrical responses of rat islet cells maintained in culture with varying levels of glucose were determined. After culture with 2.8 or 4.2 mM glucose, the beta-cells did not respond electrically to 27.8 mM glucose. However, after culture in 5.6 mM glucose, the cells responded to 27.8 mM glucose in short term experiments with depolarization and an increase in the incidence of spike activity. Islet cells maintained in 8.4 or 14.0 mM glucose had increasingly greater (negative) membrane potentials. The incidence of glucose-induced spike activity was the greatest for cells which had been cultured in 14.0 mM glucose. Raising glucose in the culture medium from 2.8 to 14.0 mM for the last 2 days of culture restored the ability of the islets to respond electrically to glucose in short term experiments. These observations show that the electrical phenomena of the beta cell membrane are affected by alterations in the level of glucose in the culture medium and serve as reliable indicators of functional glucose sensitivity of the islet cells.

Amiloride-sensitive regulation of intracellular pH in B-cells: activation by glucose.

Alterations in intracellular pH (pHi) generated by metabolism of glucose has been proposed to be a transduction device for controlling changes in K+ conductance in the plasma membrane of the B-cell leading to depolarization and cyclic variations in the membrane potential associated with spike activity. The influence of permeable weak acids or bases and amiloride inhibition of H+ extrusion by a Na:H exchanger on glucose-induced electrical activity has suggested that the electrical events are pH-sensitive. In order to document that these conditions alter pHi, we determined the influence of glucose, propionic acid, and NH4Cl, in the presence or absence of amiloride on pHi of rat islets using [14C] DMO. Glucose, 2.8 mmol/L decreased pHi by .09 unit compared to the absence of glucose (pHi = 7.08 +/- .01, M +/- SEM) and 16.7 mmol/L glucose reduced pHi by .19 unit. The glucose dose-related decrease in pHi yielded a half-maximal response at 4 mmol/L. The addition of 0.1 mmol/L amiloride had no influence on pHi without glucose and decreased pHi in the presence of 2.8 mmol/L glucose by .14 unit. The addition of 20 mmol/L propionic acid to 2.8 mmol/L glucose reduced pHi to 6.85 +/- .05, whereas 20 mmol/L NH4Cl increased pHi to 7.27 +/- .07. The addition of amiloride did not further lower the reduction in pHi elicited by 20 mmol/L propionic acid or 16.7 mmol/L glucose. These results suggest that the amiloride-sensitive Na:H exchanger plays a major role in regulation of pHi, but another modality for pHi regulation exists to compensate for inhibition of Na:H exchange under conditions of an acid load.