Metalloporphyrins for treatment of unconjugated hyperbilirubinemia in neonates

BACKGROUND

Metalloporphyrins are heme analogues that inhibit heme oxygenase, the rate-limiting enzyme in the catabolism of heme to bilirubin. By preventing the formation of bilirubin, they have the potential to reduce the level of unconjugated bilirubin in neonates and thereby reduce the risk of neonatal encephalopathy and long term neurodevelopmental impairment from bilirubin toxicity to the nervous system.

OBJECTIVES

1. To determine the efficacy of metalloporphyrins in reducing bilirubin levels, reducing the need for phototherapy or exchange transfusion and reducing the incidence of bilirubin encephalopathy in neonates with unconjugated hyperbilirubinemia when compared to placebo, phototherapy or exchange transfusion. 2. To determine the nature and frequency of side effects of metalloporphyrins when used to treat unconjugated hyperbilirubinemia in neonates.

SEARCH STRATEGY

We searched Medline (1966 - January 2003) and the Cochrane Controlled Trials Register (CCTR) from the Cochrane Library (2003, issue 1). We hand-searched the articles cited in each publication obtained. We hand searched the abstracts of the Society for Pediatric Research (USA) (published in Pediatric Research) for the years 1985 - 2002.

SELECTION CRITERIA

We included only randomized controlled studies, in which preterm or term neonates (age 28 days of life or less) with unconjugated hyperbilirubinemia due to any cause were randomly allocated to receive a metalloporphyrin in the treatment arm(s), and to receive a placebo or a conventional treatment (phototherapy or exchange transfusion) or no treatment for hyperbilirubinemia in the comparison arm(s). Any preparation of metalloporphyrin could be used, in any form, by any route, at any dose.

DATA COLLECTION AND ANALYSIS

Two authors extracted data independently. Data were entered into Revman by one author and checked by a second author. Prespecified subgroup analyses were planned in term versus preterm infants, hemolytic versus non-hemolytic causes of jaundice and according to the type of metalloporphyrin used.

MAIN RESULTS

Three small studies, enrolling a total of 170 infants, were eligible for inclusion in this review. None blinded intervention or outcome assessment. In all three studies some patients were excluded after randomization. Metalloporphyrin-treated infants appeared to have short-term benefits compared to controls, including a lower maximum plasma bilirubin level in one study, a lower frequency of severe hyperbilirubinemia in one study, a decreased need for phototherapy, fewer plasma bilirubin measurements and a shorter duration of hospitalization. None of the enrolled infants required an exchange transfusion in the two studies that described this outcome. None of the studies reported on neonatal kernicterus, death, long-term neurodevelopmental outcomes or iron deficiency anemia. Though a small number of metalloporphyrin-treated as well as control infants developed a photosensitivity rash, the trials were too small to rule out an increase in the risk of photosensitivity or other adverse effects from metalloporphyrin treatment. No subgroup analyses were possible due to the small number of included trials.

REVIEWER'S CONCLUSIONS

Treatment of neonatal unconjugated hyperbilirubinemia with metalloporphyrins may reduce neonatal bilirubin levels and decrease the need for phototherapy and hospitalization. There is no evidence to support or refute the possibility that treatment with a metalloporphyrin decreases the risk of neonatal kernicterus or of long-term neurodevelopmental impairment due to bilirubin encephalopathy. There is no evidence to support or refute the possibility that cutaneous photosensitivity is increased with metalloporphyrin treatment. Routine treatment of neonatal unconjugated hyperbilirubinemia with a metalloporphyrin cannot be recommended at present.

"Molecular rulers" for calibrating phenotypic effects of telomere imbalance

As a result of the increasing use of genome wide telomere screening, it has become evident that a significant proportion of people with idiopathic mental retardation have subtle abnormalities involving the telomeres of human chromosomes. However, during the course of these studies, there have also been telomeric imbalances identified in normal people that are not associated with any apparent phenotype. We have begun to scrutinize cases from both of these groups by determining the extent of the duplication or deletion associated with the imbalance. Five cases were examined where the telomere rearrangement resulted in trisomy for the 16p telomere. The size of the trisomic segment ranged from approximately 4-7 Mb and the phenotype included mental and growth retardation, brain malformations, heart defects, cleft palate, pancreatic insufficiency, genitourinary abnormalities, and dysmorphic features. Three cases with telomeric deletions without apparent phenotypic effects were also examined, one from 10q and two from 17p. All three deletions were inherited from a phenotypically normal parent carrying the same deletion, thus without apparent phenotypic effect. The largest deletion among these cases was approximately 600 kb on 17p. Similar studies are necessary for all telomeric regions to differentiate between those telomeric rearrangements that are pathogenic and those that are benign variants. Towards this goal, we are developing "molecular rulers" that incorporate multiple clones at each telomere that span the most distal 5 Mb region. While telomere screening has enabled the identification of telomere rearrangements, the use of molecular rulers will allow better phenotype prediction and prognosis related to these findings.

Glutamate and GABA content of calbindin-immunoreactive nerve terminals in the rat intermediolateral cell column

Immunoreactivity for calbindin-D28K (calbindin) occurs in some bulbospinal vasopressor neurons in the rostral ventrolateral medulla and calbindin-immunoreactive terminals form synapses in the intermediolateral cell column (IML), where the cell bodies of sympathetic preganglionic neurons are located. In this study, we used post-embedding immunogold labelling to determine whether calbindin terminals in the IML contained the excitatory amino acid neurotransmitter glutamate. We also assessed GABA immunoreactivity in semi-serial sections through the same terminals since this inhibitory amino acid transmitter is present in the inputs to sympathetic preganglionic neurons that lack glutamate. Analysis of 42 calbindin-positive terminals whose postsynaptic targets were not identified revealed two major groups on the basis of amino acid content. One group was immunoreactive for glutamate; and the other, for GABA. In addition, about 20% of the calbindin terminals were positive for both glutamate and GABA. Our anatomical methods cannot differentiate whether this third group is a subset of the GABAergic terminals or a separate population capable of co-releasing the two amino acids.

Parental coping with children's negative emotions: relations with children's emotional and social responding

This study examined the relation between parents' reactions to children's negative emotions and social competence. Additionally, the role of parental emotional distress in children's emotional socialization was examined. The emotional reactions of 57 preschoolers (33 girls, 24 boys; M age = 59.2 months) were observed during their free-play interactions. Parents (mostly mothers) completed questionnaires about their reactions to children's negative emotions. An index of children's social competence was obtained from teachers. Results indicated that the relation between harsh parental coping strategies and children's emotional responding was moderated by parental distress. In addition, the relation of the interaction of parental coping and distress to children's social competence was mediated by children's level of emotional intensity. It was concluded that distressed parents who use harsh coping strategies in response to children's negative emotions have children who express emotion in relatively intense ways. In turn, these children find it relatively difficult to behave in a socially competent manner.

The stability and consequences of young children's same-sex peer interactions

This article addresses whether young children's play-partner choices are stable over time and how these choices influence behavior. Sixty-one children (28 boys and 33 girls; mean age = 53 months) were observed over 6 months, and type of play behavior and sex of play partners were recorded. Children's partner preferences were highly sex differentiated and stable over time, especially when larger aggregates of data were used. Two types of consequences were identified: a binary effect that influenced differences between the sexes and a social dosage effect that influenced variations within the sexes. The binary effect reflected a pattern in which the more both girls and boys played with same-sex partners, the more their behavior became sex differentiated. The social dosage effect reflected a pattern in which variations in levels of same-sex play in the fall contributed significantly to variations in the spring above initial levels of the target behaviors.

Evaluation of patients with decreased vision or blindness

A good ocular examination and careful evaluation of the pupillary light reflexes will localize most lesion(s) producing a complaint of blindness. Lesions of the clear media severe enough to produce blindness will prohibit fundus examination. Retinal, optic nerve, and complete chiasmal lesions will produce dilated, slowly reactive pupils. Retinal blindness is usually associated with dramatic ophthalmoscopic lesions of diffuse altered reflectivity and vascular attenuation, the major exceptions being the sudden acquired retinal degeneration syndrome and some patients with glaucoma. Optic nerve lesions may involve the optic disc where they may be recognized by either pallor or hyperemia and cupping or elevation. Confirmation of optic nerve blindness in practice usually is by ruling out retinal blindness, but a more definitive methodology is to have a normal electroretinogram, slow or absent direct pupillary light reflexes (PLR), and abnormal visual evoked potentials. Central blindness is diagnosed by normal eyes, normal PLR, and often central nervous system (CNS) signs indicative of a diffuse or multifocal CNS disease.

Tracer-toxins: cholera toxin B-saporin as a model

We have shown previously that retrogradely-transported cholera toxin B (CTB)-saporin has eliminated sympathetic preganglionic neurons by 7 days after injection (Llewellyn-Smith, I.J., Martin, C.L., Arnolda, L.F., Minson, J.B., 1999. NeuroReport 10, 307). To ascertain whether this tracer-toxin can kill other types of neurons that transport CTB retrogradely with a similar time course, we injected CTB-saporin into the facial nerves of rats and allowed them to survive for 7 days. Facial motoneurons were counted ipsilateral and contralateral to the injected nerves in sections of perfused medulla processed to reveal immunoreactivity for choline acetyltransferase (ChAT). There was a statistically significant decrease in the number of ChAT-immunoreactive neurons ipsilateral to the injected nerve in three out of nine rats. Inadequate injections were probably the reason that most rats showed no decrease in motoneurons numbers after treatment with CTB-saporin, since the staining intensity and numbers of facial motoneurons that showed CTB-immunoreactivity varied markedly between rats after retrograde tracing with unconjugated CTB. These results show that CTB-saporin can eliminate motoneurons as well as sympathetic preganglionic neurons, indicate that protocols for the injection of tracer-toxins should be optimized to ensure maximum neuronal death and support our contention that CTB-saporin should kill any central neuron that expresses GM1 ganglioside, the membrane component to which CTB binds.

Effects of 0.005% latanoprost solution on intraocular pressure in healthy dogs and cats

OBJECTIVE

To evaluate effects of daily topical ocular administration of latanoprost solution on intraocular pressure (IOP) in healthy cats and dogs.

ANIMALS

9 domestic shorthair cats and 14 dogs.

PROCEDURE

Latanoprost solution (0.005%) was administered topically to 1 eye (treated) and vehicle to the other eye (control) of all animals once daily in the morning for 8 days. Intraocular pressure was measured twice daily for the 5 days preceding treatment, and IOP, pupillary diameter, conjunctival hyperemia, and blepharospasm were measured 0, 1, 6, and 12 hours after the first 4 treatments and 0 and 12 hours after the final 4 treatments. Measurements continued twice a day for 5 days after treatment was discontinued. Aqueous flare was measured once daily during and for 5 days after the treatment period.

RESULTS

Intraocular pressure and pupillary diameter were significantly decreased in the treated eye of dogs, compared with the control eye. Mild conjunctival hyperemia was also detected, but severity did not differ significantly between eyes. Blepharospasm and aqueous flare were not detected in either eye. Intraocular pressure in cats was not significantly affected by treatment with latanoprost. However, pupillary diameter was significantly decreased in the treated eye, compared with the control eye. Conjunctival hyperemia, aqueous flare, and blepharospasm were not detected in either eye.

CONCLUSIONS AND CLINICAL RELEVANCE

Once-daily topical ocular administration of latanoprost solution (0.005%) reduced IOP in healthy dogs without inducing adverse effects but did not affect IOP in healthy cats. Latanoprost may be useful for treating glaucoma in dogs.

The effect of smoking on pre-eclampsia in twin pregnancy

OBJECTIVE

To assess the effect of smoking on the incidence of pre-eclampsia and on perinatal outcome in twin pregnancy.

DESIGN

Retrospective study using Aberdeen Maternity and Neonatal Databank.

SETTING

Grampian, Orkney and Shetland.

POPULATION

All 1,575 twin pregnancies delivered in the years 1969-1971 and 1976-1997 (when smoking data were available).

METHODS

In all twin pregnancies the effects of smoking on pre-eclampsia were analysed by parity and gestation at delivery. The effect of smoking upon late miscarriage and perinatal outcome was analysed without subdivision.

MAIN OUTCOME MEASURES

Pre-eclampsia and perinatal outcome.

RESULTS

Primiparae had significantly higher rates of pre-eclampsia than multiparae and were delivered significantly earlier. The incidence of pre-eclampsia in smokers was significantly lower only in multiparae. Length of gestation was significantly shorter in multiparous smokers. The effect of smoking on pre-eclampsia appeared to be direct in multiparae but possibly indirect in primiparae (by causing earlier delivery). Smokers had a higher late miscarriage rate than nonsmokers.

CONCLUSIONS

In twin pregnancy the apparent protective effect of smoking against pre-eclampsia is significant only in multiparae, suggesting that in primiparae the smoking effect is overwhelmed by the other reasons for the development of pre-eclampsia. Smoking in twin pregnancy is not recommended due to the worse fetal outcome rates.

Corticotropic and serotonergic responses to acute stress with/without prior exercise training in different rat strains

The ability to cope with exercise training depends both on environmental and genetic background; however, whether the genetic status may affect (i) the hormonal status of trained subjects and, (ii) its responses to a heterotypic stressor is unknown. Herein, we have used Spontaneously Hypertensive Rats (SHR) and Lewis rats, that differ with regard to their psychoneuroendocrine profiles, to study the influences of an 8-week training programme and/or a 1-h immobilization stress on plasma adrenocorticotropin (ACTH) and corticosterone levels. In addition, brain serotonin metabolism was also measured as an index of neurochemical reactivity to stress. The amplitude of immobilization-elicited increases in ACTH levels which differed with the rat strain (Lewis > SHR), was amplified by prior training; besides, training decreased the strain difference in basal corticosterone (SHR > Lewis) and affected corticosterone response to immobilization in a strain-dependent manner. Thus, immobilization, which increased corticosterone levels in sedentary Lewis but not in SHRs, did not reveal interstrain differences in trained rats. Taken with the observation of a stimulatory effect of training on adrenal weights in SHRs, but not in Lewis, it is concluded that the effects of training on the corticotropic axis depend on the genetic profile of the individual. Lastly, training amplified the response of midbrain (but not striatum or hippocampus) serotonin metabolism to immobilization in a strain-independent manner although the levels of serotonin precursor, namely tryptophan, varied with training and immobilization in a strain-dependent manner. This study shows that some neuroendocrine and neurochemical effects of training undergo interindividual variability.

Criteria for evaluating the significance of developmental research in the twenty-first century: force and counterforce

Since its birth approximately 100 years ago, the field of child development has undergone fluctuations in the criteria used to determine which research topics are more or less worthy of study. The purpose of this paper is to identify the forces that influence how developmental research is prioritized and evaluated and how these influences are changing as we enter the new millennium. We do so by considering the developmental researcher in context and suggest that there will be increasing pressure to use new criteria when assessing the significance of twenty-first-century developmental science. We review the three most commonly used forms of research validity--internal, external, and ecological--and then identify new research validities that we believe are likely to play increasingly important roles in the next millennium. We also argue that many developmental scientists will increasingly be pressured by forces that are external to the traditional research environment and that these forces will shape the ways in which the significance of developmental research is evaluated.

Sino-orbital aspergillosis in a dog

Fungal rhinitis-sinusitis with orbital involvement was diagnosed in a dog with profuse unilateral ocular and bilateral nasal discharge, enophthalmos, and a corneal descemetocele. The descemetocele was treated with a conjunctival pedicle graft. Frontal sinusotomy was performed, and clotrimazole was infused through catheters placed in the frontal sinuses and nasal cavities to saturate the tissues for 1 hour. Successful resolution of orbital infection may have been aided by a fistula between the frontal sinus and orbit that allowed delivery of clotrimazole to the orbit. The dog retained sight in the affected eye, and clinical signs of infection were not detected 14 months later, although enophthalmos and medial strabismus may have been caused by persistent postinflammatory fibrosis.

Brow suspension for treatment of ptosis and entropion in dogs with redundant facial skin folds

Brow suspension surgery was performed on 7 dogs with redundant facial skin folds, associated ptosis, and entropion. The surgical technique involved subcutaneous placement of polyester mesh strips to suspend the upper eyelid from the dorsal frontalis muscle and the underlying periosteum of the skull. Visual impairment associated with ptosis was resolved in all dogs at the 2 week reevaluation period. Upper eyelid position was maintained in 4 of 7 dogs available for long-term follow-up. One dog developed persistent draining tracts in the region of the implant, and removal of part of the implanted mesh was eventually required. Upper eyelid height in this dog, however, was maintained following mesh removal, probably because of fibrosis around the implant. Brow suspension is an option for surgical management of upper eyelid ptosis and entropion in dogs with redundant skin folds and avoids the need for facial skin fold excision.

Retrogradely transported CTB-saporin kills sympathetic preganglionic neurons

Aiming to ablate sympathetic preganglionic neurons (SPN) innervating a defined target, we injected saporin conjugated to cholera toxin B subunit (CTB) unilaterally into the superior cervical ganglion of rats. In spinal cord segments T1-T3, the numbers of cholinergic neurons in the intermediolateral cell column ipsilateral and contralateral to the injected ganglion were significantly different by 3 days post-injection. By day 14, 77% of ipsilateral cholinergic neurons had disappeared. A higher percentage of neurons were killed in T1-T2 than in T3. Comparing SPN counts from CTB-saporin injected rats and counts from rats receiving unconjugated CTB into the superior cervical ganglion indicated that 84% of SPN supplying the ganglion had died by 14 days. Retrogradely transported CTB-saporin kills sympathetic preganglionic neurons and may also eliminate other types of neurons that transport CTB.

Roles of temperamental arousal and gender-segregated play in young children's social adjustment

The hypothesis that gender differences in children's adjustment is partially influenced by differences in temperament and interactions with same-sex peers was examined. Fifty-seven predominantly White, middle-class preschoolers (29 boys and 28 girls, M age = 54.5 months) participated. Measures were taken of children's arousability, problem behaviors, and tendencies to play with same-sex peers. A semester later, children's peer status was assessed. Analyses revealed that arousability and same-sex peer play interacted to predict problem behaviors. For boys high in arousability, play with same-sex peers increased problem behaviors. In contrast, arousable girls who played with other girls were relatively unlikely to show problem behaviors. Moreover, the interaction of arousability and same-sex peer play predicted boys' (but not girls') peer status, and this relation was partially mediated by problem behaviors. The role of gender-related processes is discussed.

A developmental perspective of self-construals and sex differences: comment on Cross and Madson (1997)

S. E. Cross and L. Madson (1997) proposed that women and men differ in self-construals, with women as interdependent and men as independent, and that these construals are seen to underlie many sex differences in social behavior. In this article, the authors address the issues of sex differences in self-construals, the stability of self-construals, and the centrality of interdependence-independence to sex differences. They examine the proposal next from a developmental perspective, suggesting that development of the self does not precede children's gender-related behavior. Evidence regarding the socialization processes that may contribute to sex differences in self-construals is largely inconclusive, especially regarding the differential treatment of boys and girls by parents. Their developmental perspective provides insights into ways that Cross and Madson's approach can be elaborated to explain sex differences in social behavior.

Roles of temperamental arousal and gender-segregated play in young children's social adjustment

The hypothesis that gender differences in children's adjustment is partially influenced by differences in temperament and interactions with same-sex peers was examined. Fifty-seven predominantly White, middle-class preschoolers (29 boys and 28 girls, M age = 54.5 months) participated. Measures were taken of children's arousability, problem behaviors, and tendencies to play with same-sex peers. A semester later, children's peer status was assessed. Analyses revealed that arousability and same-sex peer play interacted to predict problem behaviors. For boys high in arousability, play with same-sex peers increased problem behaviors. In contrast, arousable girls who played with other girls were relatively unlikely to show problem behaviors. Moreover, the interaction of arousability and same-sex peer play predicted boys' (but not girls') peer status, and this relation was partially mediated by problem behaviors. The role of gender-related processes is discussed.

Neurokinin-1 receptor-immunoreactive sympathetic preganglionic neurons: target specificity and ultrastructure

Substance P is involved in cardiovascular control at the spinal cord level, where it acts through neurokinin-1 receptors. In this study we used immunocytochemistry and retrograde tracing to investigate the presence of the neurokinin-1 receptor and its ultrastructural localization in rat sympathetic preganglionic neurons that project to the superior cervical ganglion or the adrenal medulla. Immunofluorescence for the neurokinin-1 receptor outlined the somatic and dendritic surfaces of neurons in autonomic subnuclei of spinal cord segments T1-T12, whereas immunofluorescence for the tracer, cholera toxin B subunit, filled retrogradely labelled cells. There was a significant difference in the proportion of neurokinin-1 receptor-immunoreactive sympathetic preganglionic neurons supplying the superior cervical ganglion and the adrenal medulla. Thirty-eight percent of the neurons that projected to the superior cervical ganglion were immunoreactive for the neurokinin-1 receptor compared to 70% of neurons innervating the adrenal medulla. Of neurons projecting to the superior cervical ganglion, significantly different proportions showed neurokinin-1 receptor immunoreactivity in spinal cord segment T1 (15%) versus segments T2 T6 (45%). At the ultrastructural level, neurokinin-1 receptor staining occurred predominantly on the inner leaflets of the plasma membranes of retrogradely labelled sympathetic preganglionic neurons. Deposits of intracellular label were often observed in dendrites and in the rough endoplasmic reticulum and Golgi apparatus of cell bodies. Neurokinin-1 receptor immunoreactivity was present at many, but not all, synapses as well as at non-synaptic sites, and occurred at synapses with substance P-positive as well as substance P-negative nerve fibres. Only 37% of the substance P synapses occurred on neurokinin-1-immunoreactive neurons in the intermediolateral cell column. These results show that presence of the neurokinin-1 receptor in sympathetic preganglionic neurons is related to their target. The ultrastructural localization of the receptor suggests that sympathetic preganglionic neurons may be affected (i) by substance P released at neurokinin-1 receptor-immunoreactive synapses, (ii) by other tachykinins (e.g., neurokinin A), which co-localize in substance P fibres in the intermediolateral cell column, acting through other neurokinin receptors, and (iii) by substance P that diffuses to neurokinin-1 receptors from distant sites.

Comparison of bidisomide, flecainide and dofetilide on action potential duration in isolated canine atria: effect of isoproterenol

Prolongation of action potential duration (APD) and the effective refractory period (ERP) is one mechanism to prevent reentrant atrial and ventricular arrhythmias. Because arrhythmias are usually associated with an elevated sympathetic tone and increase of circulating catecholamines, the potential influence of catecholamines on antiarrhythmic effects of an agent are critical to predicting the potential clinical response. In this study the effects of three different antiarrhythmic agents, bidisomide, flecainide and dofetillide, each of which prolongs atrial ERP, were compared before and after treatment with isoproterenol, a beta-adrenergic agonist. Standard intracellular microelectrode recording techniques were used to record action potentials from isolated canine atrial tissue. Bidisomide and flecainide elicited a 20 to 27 msec increase in APD and ERP that was independent of stimulation frequency (1-5 Hz). Dofetilide prolonged APD and ERP at 1 Hz (40 and 37 msec, respectively) but was completely ineffective at 5 Hz. After equilibration with the anti-arrhythmic agent, tissues were additionally exposed to isoproterenol. Only bidisomide prolonged APD and ERP in the presence of isoproterenol. In the converse series of experiments after treatment with isoproterenol, which caused a 20 to 30% reduction in APD and ERP, only bidisomide completely reversed the effect of 1 microM isoproterenol. Bidisomide was inactive in a functional beta-adrenergic antagonism assay, thus ruling out beta-adrenergic blockade as a potential mechanism. These results indicate that bidisomide, unlike flecainide and dofetilide was able to prolong APD and ERP in isolated canine atrium even at high stimulation frequencies and in the presence of isoproterenol. These data suggest that bidisomide would be effective in the presence of elevated sympathetic tone and on the agents studied, only bidisomide possessed a unique and desirable antiarrhythmic profile.

T cell activation is regulated by voltage-dependent and calcium-activated potassium channels

Membrane potential (Vm) is tightly controlled in T cells through the regulated flux of ions across the plasma membrane. To investigate the functional role of voltage-dependent (Kv) and calcium-activated (KCa) potassium channels in T cell activation, we compared the effects of two K+ channel blockers, namely kaliotoxin (KTX) and charybdotoxin (CHTX), on Vm, calcium influx, and cell proliferation. KTX potently inhibited Kv (ID50 = 3 nM) but not KCa (ID50 = 5 microM) currents in T cells. Resting T cells exposed to KTX (300 nM) depolarized from -56 mV to -50 mV. KTX had no effect on the transient membrane hyperpolarization that characteristically follows receptor-mediated T cell stimulation. However, T cells stimulated in the presence of KTX subsequently depolarized to -40 mV. KTX also reduced the steady state intracellular free calcium concentration ([Ca2+]i) in stimulated cells by 19% and inhibited T cell proliferation by 35%. CHTX potently inhibited both Kv and KCa currents (ID50 = approximately 1 nM). CHTX (300 nM) depolarized resting T cells to -48 mV, equivalent to the effect observed for KTX. In stimulated T cells, 300 nM CHTX completely blocked the induced hyperpolarization and subsequently depolarized the cells to -21 mV. These effects were associated with a 45% reduction in peak [Ca2+]i, a 60% decrease in steady state [Ca2+]i, and 63% inhibition of T cell proliferation. These results suggest that both Kv and KCa conductances contribute to the underlying mechanisms of T cell activation.

T cell activation is regulated by voltage-dependent and calcium-activated potassium channels

Membrane potential (Vm) is tightly controlled in T cells through the regulated flux of ions across the plasma membrane. To investigate the functional role of voltage-dependent (Kv) and calcium-activated (KCa) potassium channels in T cell activation, we compared the effects of two K+ channel blockers, namely kaliotoxin (KTX) and charybdotoxin (CHTX), on Vm, calcium influx, and cell proliferation. KTX potently inhibited Kv (ID50 = 3 nM) but not KCa (ID50 = 5 microM) currents in T cells. Resting T cells exposed to KTX (300 nM) depolarized from -56 mV to -50 mV. KTX had no effect on the transient membrane hyperpolarization that characteristically follows receptor-mediated T cell stimulation. However, T cells stimulated in the presence of KTX subsequently depolarized to -40 mV. KTX also reduced the steady state intracellular free calcium concentration ([Ca2+]i) in stimulated cells by 19% and inhibited T cell proliferation by 35%. CHTX potently inhibited both Kv and KCa currents (ID50 = approximately 1 nM). CHTX (300 nM) depolarized resting T cells to -48 mV, equivalent to the effect observed for KTX. In stimulated T cells, 300 nM CHTX completely blocked the induced hyperpolarization and subsequently depolarized the cells to -21 mV. These effects were associated with a 45% reduction in peak [Ca2+]i, a 60% decrease in steady state [Ca2+]i, and 63% inhibition of T cell proliferation. These results suggest that both Kv and KCa conductances contribute to the underlying mechanisms of T cell activation.

Children's gender-based reasoning about toys

The goal of these studies was to investigate how preschool children use gender-based reasoning in making judgments about toy preferences for themselves and for others. In Studies 1 and 2, children (n = 22, n = 71) were shown unfamiliar, non-sex-typed toys and asked to rate how much they, other girls, and other boys would like each toy. As expected, children made gender-based inferences: "What I like, children of my sex will also like, and children of the other sex will not like." Study 3 was designed to assess how children use gender-based reasoning to make decisions about attractive and unattractive toys when they are given gender labels. Children (n = 91) were shown unfamiliar toys varying in attractiveness that were given explicit gender labels (e.g., "this is a toy girls really like") or no label. With a different experimenter (to avoid demand characteristics), children rated their own and others' liking of the toys. Children used gender labels to guide their own preferences and their expectations for others. Even with very attractive toys, children liked toys less if they were labeled as being for the other sex, and expected other girls and boys to do the same. The role of gender-based reasoning in cognitive theories of gender and on children's play preferences is discussed.

Ophthalmic cyclosporine in equine keratitis and keratouveitis: 11 cases

Topical cyclosporine A was safely used in a series of 11 cases of equine keratitis and keratouveitis and appeared to be an effective anti-inflammatory agent in 9 cases. The clinical diagnoses included interstitial keratouveitis, endotheliitis, multifocal punctate keratopathy and a melting stromal ulcer. In most cases, the presence or absence of insidious bacterial infection was not conclusively determined. Topical cyclosporine A had no deleterious effects in this series of cases. The authors suggest that topical cyclosporine in both aqueous and lipid base vehicles should be investigated and evaluated as an alternative mode of achieving ocular immunosuppression.

Treated delinquent boys' substance use: onset, pattern, relationship to conduct and mood disorders

We describe relationships between substance use, conduct disorder (CD), depression, and history of self-injury or suicide attempts, in referred, delinquent, substance involved, adolescent males. Sixty youths (mean age 16.3 years) completed standardized assessments for substance use and other psychiatric disorders, aggressiveness, and social class. All boys met modified criteria for CD. Most had high aggression ratings. Twenty percent had depressive diagnoses. By age 13, 78% had begun regular substance use. Marijuana was the first substance for 42%. The boys had substance dependence on a mean of 3.2 different drugs (usually including alcohol and marijuana), with abuse of an average of one additional drug. CD symptoms began 3.6 years (mean) before regular use. CD symptom count correlated with number of dependence diagnoses, and both of those (but not depression) related significantly to suicide attempt and self-injury histories. Improved understanding of substance involvement in youths with CD may generate more rational prevention and treatment.