High hydroxyurea usage in sickle cell anemia regardless of patient demographics

Hydroxyurea is highly effective in sickle cell disease, but it is still underutilized. Reports of hydroxyurea utilization largely use Medicaid data, and socioeconomics is often cited as a barrier. To address whether patient demographics influenced the high hydroxyurea usage rate recently reported for the pediatric sickle cell program of Northern Virginia, analysis of data from 2011 to 2021 revealed no statistical difference in hydroxyurea usage rate between Medicaid and non-Medicaid, African American and African, or age less than 13 and age greater than or equal to 13 years cohorts, demonstrating that hydroxyurea can be successfully implemented across demographic groups.

Effect of voxelotor on cardiopulmonary testing in youths with sickle cell anemia in a pilot study

BACKGROUND

Individuals with sickle cell anemia (SCA) exhibit decreased exercise capacity. Anemia limits oxygen-carrying capacity and affects cardiopulmonary fitness. The drug voxelotor raises hemoglobin in SCA. We hypothesized that voxelotor improves exercise capacity in youths with SCA.

METHODS

In a single-center, open-label, single-arm, longitudinal interventional pilot study (NCT04581356), SCA patients aged 12 and older, stably maintained on hydroxyurea, were treated with 1500 mg voxelotor daily, and performed cardiopulmonary exercise testing before (CPET#1) and after voxelotor (CPET#2). A modified Bruce Protocol was performed on a motorized treadmill, and breath-by-breath gas exchange data were collected. Peak oxygen consumption (peak VO₂ ), anaerobic threshold, O₂ pulse, VE/VCO₂ slope, and time exercised were compared for each participant. The primary endpoint was change in peak VO₂ . Hematologic parameters were measured before each CPET. Patient Global Impression of Change (PGIC) and Clinician Global Impression of Change (CGIC) surveys were collected.

RESULTS

Ten hemoglobin SS patients aged 12-24 completed the study. All demonstrated expected hemoglobin rise, with average +1.6 g/dL (p = .003) and P₅₀ left shift of average -11 mmHg (p < .0001) with decreased oxygen off-loading at low pO₂ . The change in % predicted peak VO₂ from CPET#1 to CPET#2 ranged from -12.8% to +11.3%, with significant improvement of more than 5% in one subject, more than 5% decrease in five subjects, and insignificant change of less than 5% in four subjects. All 10 CGIC and seven of 10 PGIC responses were positive.

CONCLUSION

In a plot study of 10 youths with SCA, voxelotor treatment did not improve peak VO₂ in 9 out of 10 patients.

Comparison of suspected and confirmed internal EVD-related infections: a prospective multi-centre U.K. observational study

Background

Diagnosis of internal external ventricular drain (EVD)-related infections (iERI) is an area of diagnostic difficulty. Empiric treatment is often initiated on clinical suspicion. There is limited guidance around antimicrobial management of confirmed versus suspected iERI.

Methods

Data on patients requiring EVD insertion were collected from 21 neurosurgical units in the United Kingdom from 2014 to 2015. Confirmed iERI was defined as clinical suspicion of infection with positive cerebrospinal fluid (CSF) culture and/or Gram stain. Cerebrospinal fluid, blood, and clinical parameters and antimicrobial management were compared between the 2 groups. Mortality and Modified Rankin Scores were compared at 30 days post-EVD insertion.

Results

Internal EVD-related infection was suspected after 46 of 495 EVD insertions (9.3%), more common after an emergency insertion. Twenty-six of 46 were confirmed iERIs, mostly due to Staphylococci (16 of 26). When confirmed and suspected infections were compared, there were no differences in CSF white cell counts or glucose concentrations, nor peripheral blood white cell counts or C-reactive protein concentrations. The incidence of fever, meningism, and seizures was also similar, although altered consciousness was more common in people with confirmed iERI. Broad-spectrum antimicrobial usage was prevalent in both groups with no difference in median duration of therapy (10 days [interquartile range {IQR}, 7–24.5] for confirmed cases and 9.5 days [IQR, 5.75–14] for suspected, P = 0.3). Despite comparable baseline characteristics, suspected iERI was associated with lower mortality and better neurological outcomes.

Conclusions

Suspected iERI could represent sterile inflammation or lower bacterial load leading to false-negative cultures. There is a need for improved microbiology diagnostics and biomarkers of bacterial infection to permit accurate discrimination and improve antimicrobial stewardship.

Ten-year Longitudinal Analysis of Hydroxyurea Implementation in a Pediatric Sickle Cell Program

Hydroxyurea (HU) has proven benefit in sickle cell anemia (SCA), but HU is still underutilized. The Pediatric Sickle Cell Program of Northern Virginia prescribes HU regardless of symptoms to all SCA patients age ≥ 9 months and prospectively tracks outcomes. HU is dosed to maximum tolerated dosing (MTD), targeting 30% Hgb F. Longitudinal data from 2009-2019 encompassing 1222 HU-eligible and 950 HU-exposure patient-years were analyzed in 2-year intervals for hemoglobin (Hgb), fetal hemoglobin (Hgb F), hospitalizations, transfusions, and treat-and-release ED visits. Comparing HU-eligible patients in the interval prior to HU implementation (2009-2011) to the last interval analyzed after HU implementation (2017-2019), HU usage increased from 33% to 93%, average Hgb increased from 8.3±0.98 to 9.8±1.3 g/dL (p<0.0001), average Hgb F rose from 13±8.7% to 26±9.9% (p<0.0001), hospitalizations decreased from 0.71 (95% CI 0.54-0.91) to 0.2 (95% CI 0.13-0.28) admissions/person-year, sporadic transfusions decreased from 0.4 (95% CI 0.27-0.55) to 0.05 (95% CI 0.02-0.12) transfusions/person-year. Treat-and-release ED visit rates remained unchanged, varying between 0.49 (95% CI 0.36-0.64) and 0.64 (95% CI 0.48-0.83) visits/person-year. By the last interval, 72% of patients had Hgb ≥ 9g/dL, 42% had Hgb F ≥ 30%, 79% experienced no hospitalizations, and 94% received no transfusions. Uniform HU prescription for SCA patients with close monitoring to achieve high Hgb F resulted in significant improvements in laboratory and clinical outcomes within 2 years, which continued to improve over the next 6 years. Rigorous HU implementation in a pediatric sickle cell population is feasible, effective, and sustainable. This article is protected by copyright. All rights reserved.

O-156 Role of botulinum toxin for the treatment of sexual and pelvic pain in endometriosis

Pelvic pain persists despite standard care in about 30% of women with a history of endometriosis and pain. Pelvic pain may be accompanied by spasm in pelvic floor muscles that results in sexual pain, impairs intimacy, and might contribute to maintenance of chronic pelvic pain. These women also often have pain sensitization, within and beyond the pelvis.  Botulinum toxin is commonly used for conditions with muscle overactivity and pain.  We therefore evaluated its potential to decrease pelvic floor spasm and ameliorate chronic pelvic pain in such women.  In a randomized, double-masked, placebo-controlled trial, women aged 18-50 years with surgically diagnosed endometriosis and chronic pelvic pain despite optimized hormonal treatment received 100U onabotulinumtoxinA or placebo into pelvic floor muscles with palpable spasm (NCT01553201).  At least one month after the masked injection and any time over the next year, participants could request a 2nd injection, which was always botulinum toxin, again injected into muscles with spasm. Pain and spasm were assessed before the first (masked) study injection and one month later (before a second open injection of botulinum toxin) as the primary outcome measure and then at regular intervals over the next year, including after the optional 2nd injection. The women were able to continue their regular pain medications while in the study but were asked not to change any hormonal treatments they were using. Pain medication usage and other aspects of response, including side effects, were tracked. 

This National Institutes of Health study included 29 women who were premenopausal and who had persistent pain for over 10 years on average despite having optimized standard treatment, such as surgery and hormones, for their endometriosis.  All had pelvic floor muscle spasm and described the pelvic floor as a major focus of pain. Twenty-two of 23 reporting current hormone use had menses suppression. Nineteen of 29 characterized pelvic tenderness as focal, not diffuse.  All showed widespread myofascial dysfunction with myofascial trigger-points in &gt;two-thirds of assessed regions.  Widespread sensitization was present in 16/29; regional sensitization (thoracic: 20/29; pelvic 17/29) was common. 

The primary outcome, participants’ self-report of benefit and pain relief, showed that botulinum toxin was more likely than placebo to provide benefit. On exam, the women receiving toxin had a corresponding decrease in spasm in the muscles of the pelvic floor compared to before injection.  Twenty-seven women requested a 2nd injection, 16 at the one-month time point and 11 later in the year. The 2 patients who did not ask for a 2nd injection had received botulinum toxin and experienced persistent benefit; one subsequently became pregnant.  Over the entire year-long study, only 4 patients, two from the group who initially received botulinum toxin and two from the placebo group, did not have durable benefit even after the 2nd injection.  Sixteen women had continued benefit at the end of the study.  While there was local pain and discomfort with the intravaginal injections, there were no serious side effects attributable to the botulinum toxin itself at the 100U dose used in the study. Baseline and current disability predicted improvement in pain, sexual intercourse, functioning, fatigue and mental health scores. 

We demonstrate pelvic floor muscle spasm as part of endometriosis-associated chronic pelvic pain and relief of pain/spasm from onabotulinumtoxinA compared to placebo that persisted over time. OnabotulinumtoxinA was well-tolerated. The findings illustrate a viscero-somatic reflex relationship between endometriosis lesions and muscle spasm and suggest that pelvic floor spasm may initiate or maintain sensitization. Although additional research is needed, this study supports that onabotulinumtoxinA can safely and effectively treat chronic pelvic pain in women with a history of endometriosis and ongoing spasm in the pelvic floor muscles.

Effects of dual-tasking on time-to-boundary during stance in people with PD: A preliminary study

BACKGROUND

Quiet stance is impacted by Parkinson's disease and dual-tasking. Recently developed outcomes such as the time-to-boundary provide unique insight into balance by integrating center of pressure position with base of support. However, little is known about the effects of Parkinson's disease on time-to-boundary. In particular, the effects of distracting cognitive tasks, and how people with Parkinson's disease prioritize balance and cognitive tasks are poorly understood.

METHODS

14 people with Parkinson's disease and 13 controls completed quiet standing and cognitive Stroop tasks separately (single-task) and together (dual-task). 2-dimentional, medio-lateral, and anterior-posterior time-to-boundary were calculated via force-plate data. Traditional sway outcomes, including sway area and path length, were also calculated. Cognitive performance was measured as the verbal reaction time after auditory stimulus delivery. Prioritization was assessed by taking the difference between cognitive and postural dual-task interference.

FINDINGS

Time-to-boundary was worse in Parkinson's disease compared to controls (2-dimentional: p = .019; anterior-posterior: p = .062; medio-lateral: p = .012). Medio-lateral time-to-boundary, but not anterior-posterior, was significantly worse during dual-tasking than single-tasking (p = .024). Neurotypical adults tended to prioritize cognition over medio-lateral postural outcomes.

INTERPRETATION

People with Parkinson's disease exhibit worse time-to-boundary than their neurotypical peers, and medio-lateral outcomes were sensitive to single to dual-task performance changes. Further, participants generally showed cognitive prioritization, such that cognitive performance was less impacted than medio-lateral postural outcomes by dual-tasking.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Second-generation corneal deformation signal waveform analysis in normal, forme fruste keratoconic, and manifest keratoconic corneas after statistical correction for potentially confounding factors

PURPOSE

To evaluate the difference in corneal biomechanical waveform parameters between manifest keratoconus, forme fruste keratoconus, and healthy eyes with a second-generation biomechanical waveform analyzer (Ocular Response Analyzer 2).

SETTING

Jules Stein Eye Institute, University of California, Los Angeles, California, USA.

DESIGN

Retrospective chart review.

METHODS

The biomechanical waveform analyzer was used to obtain corneal hysteresis (CH), corneal resistance factor (CRF), and 37 biomechanical waveform parameters in manifest keratoconus eyes, forme fruste keratoconus eyes, and healthy eyes. Useful distinguishing parameters were found using t tests and a multivariable logistic regression model with stepwise variable selection. Potential confounders were controlled for.

RESULTS

The study included 68 manifest keratoconus eyes, 64 forme fruste keratoconus eyes, and 249 healthy eyes. There was a statistical difference in the mean CRF between the normal group (10.2 mm Hg ± 1.7 [SD]) and keratoconus group (6.3 ± 1.9 mm Hg) (P = .003), and between the normal group and the forme fruste keratoconus group (7.8 ± 1.4 mm Hg) (P < .0001). There was no statistical difference in the mean CH between the normal group and the keratoconus group or the forme fruste keratoconus group. The CRF, height of peak 1 (P1) (P = .001), downslope of P1 (dslope1) (P = .027), upslope of peak 2 (P2) (P = .004), and downslope of P2 (P = .006) distinguished the normal group from the keratoconus groups. The CRF, downslope of P2 derived from upper 50% of applanation peak (P = .035), dslope1 (P = .014), and upslope of P1 (P = .008) distinguished the normal group from the forme fruste keratoconus group.

CONCLUSION

Differences in multiple biomechanical waveform parameters can differentiate between healthy and diseased conditions and might improve early diagnosis of keratoconus and forme fruste keratoconus.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Skeletal findings in the first 12 months following initiation of glucocorticoid therapy for pediatric nephrotic syndrome

Incident vertebral fractures and lumbar spine bone mineral density (BMD) were assessed in the 12 months following glucocorticoid initiation in 65 children with nephrotic syndrome. The incidence of vertebral fractures was low at 12 months (6 %) and most patients demonstrated recovery in BMD Z-scores by this time point.

INTRODUCTION

Vertebral fracture (VF) incidence following glucocorticoid (GC) initiation has not been previously reported in pediatric nephrotic syndrome.

METHODS

VF was assessed on radiographs (Genant method); lumbar spine bone mineral density (LS BMD) was evaluated by dual-energy X-ray absorptiometry.

RESULTS

Sixty-five children were followed to 12 months post-GC initiation (median age, 5.4 years; range, 2.3-17.9). Three of 54 children with radiographs (6 %; 95 % confidence interval (CI), 2-15 %) had incident VF at 1 year. The mean LS BMD Z-score was below the healthy average at baseline (mean ± standard deviation (SD), -0.5 ± 1.1; p = 0.001) and at 3 months (-0.6 ± 1.1; p < 0.001), but not at 6 months (-0.3 ± 1.3; p = 0.066) or 12 months (-0.3 ± 1.2; p = 0.066). Mixed effect modeling showed a significant increase in LS BMD Z-scores between 3 and 12 months (0.22 SD; 95 % CI, 0.08 to 0.36; p = 0.003). A subgroup (N = 16; 25 %) had LS BMD Z-scores that were ≤-1.0 at 12 months. In these children, each additional 1,000 mg/m(2) of GC received in the first 3 months was associated with a decrease in LS BMD Z-score by 0.39 at 12 months (95 % CI, -0.71 to -0.07; p = 0.017).

CONCLUSIONS

The incidence of VF at 1 year was low and LS BMD Z-scores improved by 12 months in the majority. Twenty-five percent of children had LS BMD Z-scores ≤-1.0 at 12 months. In these children, LS BMD Z-scores were inversely associated with early GC exposure, despite similar GC exposure compared to the rest of the cohort.

The development of bone mineral lateralization in the arms

Bone mineral content (BMC) is known to be greater in the dominant arm after the age of 8 years. We studied a group of children and found that BMC sidedness gradually increased up to the age of 6 years and then remained stable into late adolescence.

INTRODUCTION

Bone mineral content (BMC) exhibits sidedness in the arms after the age of 8 years, but it is not known whether BMC is greater in the dominant arm from birth or whether lateralization develops in early childhood. To address this, we examined bone mineral status in relation to handedness and age.

METHODS

Subjects (N = 158) were children recently initiating glucocorticoids for underlying disease (leukemia 43 %, rheumatic conditions 39 %, nephrotic syndrome 18 %). Handedness was determined by questionnaire and BMC by dual-energy X-ray absorptiometry.

RESULTS

Median age was 7.2 years (range, 1.5 to 17.0 years), 49 % was male, and the spine BMD Z-score was -0.9 (SD, 1.3). By linear regression, BMC sidedness in the arms was significantly related to age (r = 0.294, p = 0.0005). Breakpoint analysis revealed two lines with a knot at 6.0 years (95 % CI, 4.5-7.5 years). The formula for the first line was: dominant:nondominant arm BMC ratio = 0.029 × age [in years] + 0.850 (r = 0.323, p = 0.017). The slope of the second line was not different from 0 (p = 0.332), while the slopes for the two lines were significantly different (p = 0.027).

CONCLUSIONS

These results show that arm BMC sidedness in this patient group develops up to age 6 years and then remains stable into late adolescence. This temporal profile is consistent with mechanical stimulation of the skeleton in response to asymmetrical muscle use as handedness becomes manifest.

Blockade of K(ATP) channels reduces endothelial hyperpolarization and leukocyte recruitment upon reperfusion after hypoxia

Ischemia/reperfusion injury in renal transplantation leads to slow or initial nonfunction, and predisposes to acute and chronic rejection. In fact, severe ischemia reperfusion injury can significantly reduce graft survival, even with modern immunosuppressive agents. One of the mechanisms by which ischemia/reperfusion causes injury is activation of endothelial cells resulting in inflammation. Although several therapies can be used to prevent leukocyte recruitment to ischemic vessels (e.g. antiadhesion molecule antibodies), there have been no clinical treatments reported that can prevent initial immediate neutrophil recruitment upon reperfusion. Using intravital microscopy, we describe abrogation of immediate neutrophil recruitment to ischemic microvessels by the K(ATP) antagonist glibenclamide (Glyburide). Further, we show that glibenclamide can reduce leukocyte recruitment in vitro under physiologic flow conditions. ATP-regulated potassium channels (K(ATP)) are important in the control of cell membrane polarization. Here we describe profound hyperpolarization of endothelial cells during hypoxia, and the reduction of this hyperpolarization using glibenclamide. These findings suggest that control of endothelial membrane potential during ischemia may be an important therapeutic tool in avoiding ischemia/reperfusion injury, and therefore, enhancing transplant long-term function.

[Reconstruction of the oral commissure in microstomia patients with deep dermal facial burns: a modified technique]

BACKGROUND

Deep thermal dermal wounds of the oral region with subsequent microstomia are a rare and complex indication for surgical reconstruction of the oral commissure. Apart from functional and mimic aspects, aesthetic expectations are high. Based on converse technique, we performed a reconstruction of the oral commissure in 17 patients. 8 of these needed surgical re-operation due to recurrence and insufficient results. This high rate of complications led to a modification of the surgical procedure.

PATIENTS

We present a modified technique which gave good results in our clinic. Based on Fairbank's technique, we altered the technique by covering the soft tissue defect of the lateral lip with an additional rotation flap raised from the mucosa of the enoral lower lip. Resulting scars were thereby shifted to the enoral side of the lower lip which caused less contracture in the region of the oral commissure.

RESULTS

Using this modified technique, we were able to achieve a lasting displacement of the oral commissure to the lateral side. Long-term follow-up showed good functional results with no need for additional procedures.

Laparoscopic versus open donor nephrectomy

BACKGROUND

As compared with open donor nephrectomy (OpenDN), laparoscopic donor nephrectomy (LapDN) offers donors more rapid recovery and recipients equivalent graft function, but LapDN costs remain greater. This study compared LapDN and OpenDN with cost-utility analysis.

METHODS

Utilities were assessed with time trade-off, probabilities derived from systematic review of the literature and the costs derived from 27 OpenDN and 34 LapDN patients treated contemporaneously. A societal perspective was taken. Lost employment costs were included. An incremental cost-effectiveness ratio (ICER) was calculated with best- and worst-case scenarios for confidence intervals. Sensitivity analyses assessed robustness.

RESULTS

LapDN costs are lower (11,170.71 dollars vs 12,631.91 dollars), whereas quality of life (QOL) is superior (0.7247 vs 0.6585 quality-adjusted life years [QALY], rendering LapDN a dominant strategy. The model was robust to all variables, and LapDN remained dominant from a payer perspective. In a worst-case scenario, the ICER for LapDN was at most 2,231.61 dollars per QALY.

CONCLUSIONS

LapDN offers improved QOL at lower costs, despite the fact that this analysis included patients treated during the learning curve of LapDN at our institution. By potentially increasing organ donor rates, LapDN may be further cost saving by decreasing the number of patients receiving dialysis.

Differential effect of dehydroepiandrosterone and its steroid precursor pregnenolone against the behavioural deficits in CO-exposed mice

The neuroactive steroids pregnenolone (3beta-hydroxy-5-pregnen-20-one) and dehydroepiandrosterone (DHEA, 3alpha-hydroxy-5-androstene-17-one) are negative allosteric modulators of the GABA(A) receptors and positive modulators of acetylcholine, NMDA and sigma(1) receptors. Pregnenolone was recently shown to potentiate the neuronal damage induced by excessive glutamate in cell culture models, whereas dehydroepiandrosterone was reported to present some neuroprotective activity. The in vivo relevance of these effects was investigated in mice submitted to an hypoxic insult, the repeated exposure to carbon monoxide (CO) gas, a model that leads to neurodegeneration in the CA(1) hippocampal area and learning deficits. Recording spontaneous alternation behaviour in the Y-maze assessed short-term memory and long-term memory was examined using a passive avoidance task. After exposure to CO, mice showed a progressive deterioration of their learning ability, reaching significance after 3 days and being maximal after 7 days. Pregnenolone administered before CO significantly facilitated the hypoxia-related deficits, which could be measured 1 day after CO and appeared maximal after 3 days. Dizocilpine blocked the deficits in vehicle- and pregnenolone-treated CO-exposed animals, showing that pregnenolone selectively facilitated the NMDA receptor-dependent excitotoxicity. Dehydroepiandrosterone blocked the appearance of the CO-induced deficits, even after 7 days. Interestingly, the sigma(1) receptor antagonist N, N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)ethylamine (NE-100) failed to affect the dehydroepiandrosterone-induced protection, showing the lack of involvement of sigma(1) receptors. Cresyl violet-stained sections of the mouse hippocampal formation showed that the neurodegeneration observed in the CA(1) area after exposure to CO was augmented by pregnenolone and blocked by dehydroepiandrosterone. These results show that pregnenolone and dehydroepiandrosterone, although being similarly involved in modulating the excitatory/inhibitory balance in the brain, do not equally affect the extent of excitotoxic insults.

Immunocytochemical localization of the sigma(1) receptor in the adult rat central nervous system

In order to characterize the localization of the sigma(1) receptor in the adult rat central nervous system, a polyclonal antibody was raised against a 20 amino acid peptide, corresponding to the fragment 143-162 of the cloned sigma(1) receptor protein. Throughout the rostrocaudal regions of the central nervous system extending from the olfactory bulb to the spinal cord, intense to moderate immunostaining was found to be associated with: (i) ependymocytes bordering the entire ventricular system, and (ii) neuron-like structures located within the parenchyma. Double fluorescence studies confirmed that, throughout the parenchyma, sigma(1) receptor-immunostaining was essentially associated with neuronal structures immunostained for the neuronal marker betaIII-tubulin. In all rats examined, high levels of immunostaining were always associated with neurons located within specific regions including the granular layer of the olfactory bulb, various hypothalamic nuclei, the septum, the central gray, motor nuclei of the hindbrain and the dorsal horn of the spinal cord. In contrast, only faint immunostaining was associated with neurons located in the caudate-putamen and the cerebellum. Electron microscope studies indicated that sigma(1) receptor immunostaining was mostly associated with neuronal perikarya and dendrites, where it was localized to the limiting plasma membrane, the membrane of mitochondria and of some cisternae of the endoplasmic reticulum. At the level of synaptic contacts, intense immunostaining was associated with postsynaptic structures including the postsynaptic thickening and some polymorphous vesicles, whereas the presynaptic axons were devoid of immunostaining. These data indicate that the sigma(1) receptor antibody prepared here, represents a promising tool for further investigating the role of sigma(1) receptors.

DNA-protein interactions in the proximal zeta-globin promoter: identification of novel CCACCC- and CCAAT-binding proteins

The human zeta-globin gene is expressed in a tissue- and developmental-specific pattern, with expression confined to primitive erythroid cells of the embryonic yolk sac blood islands. Transgenic mouse studies have shown that the proximal zeta-globin promoter contains sequences that contribute to the stage-specificity of expression, but no systematic functional studies of the cis elements in the proximal zeta-globin promoter have been reported. In this paper, we show that a number of conserved sequence elements in the zeta-globin promoter are important for promoter activity in transiently transfected K562 erythroleukemia cells, which constitutively express zeta-globin. These include a GATA site at -105, a CCACC site at -93, a CCAAT box at -65, and a TATA box at -29. A highly conserved CCTCC sequence at -78 is not important for zeta-globin promoter activity in this system. Mutations at these sites do not result in increased promoter activity in OCIM1 cells, an erythroid line that does not express zeta-globin, suggesting none of these sites is a developmental silencer. Electrophoretic mobility shift assays show that K562 and OCIM1 nuclear extracts contain DNA-binding activities that interact with the -105 GATA, -65 CCAAT, and -29 TATA sites. In addition K562 cells, but not OCIM1 cells, have an activity that binds the -93 CCACC site. GATA-1 interacts with the GATA site. The K562 CCACC-binding protein is distinct from Sp1, Sp2, Sp3, Sp4, EKLF, and BKLF. A specific -65 CCAAT-binding activity is present in K562 and OCIM1 nuclear extracts that is distinct from other CCAAT-binding proteins including CBF/NF-Y, C/EBP, NF-1, and CP2. Thus, we have identified two novel factors that may contribute to the tissue or developmental stage-specific expression of zeta-globin.