Association Between Psychosis in Elderly Patients With Alzheimer Disease and Impaired Social Cognition

This cohort study assesses the association between psychosis in elderly patients with Alzheimer disease and social cognition in a longitudinal study.

The Relational and Item-Specific Encoding Task in Mild Cognitive Impairment and Alzheimer Disease

BACKGROUND

The Relational and Item-Specific Encoding task (RISE) measures episodic memory subcomponents, including item-specific and relational encoding of to-be-remembered stimuli. These memory components are neurobiologically relevant because they may engage distinct subregions of the medial temporal lobe, perirhinal and entorhinal cortices, parahippocampus, and hippocampus.

METHODS

A total of 125 participants, including 84 healthy controls (HC), 22 mild cognitive impairment-diagnosed and 19 Alzheimer disease (AD)-diagnosed participants, were administered the RISE and neuropsychological measures. Stepwise linear regressions assessed prediction of functional ability from RISE d' measures. ANOVAs and logistic regressions determined the ability of the RISE to discriminate between the diagnostic groups. In addition, the psychometric properties of the RISE were examined.

RESULTS

RISE measures predicted diagnosis with pseudo R2 values in the range of 0.25-0.30. Receiver operating characteristic curves demonstrated adequate sensitivity and specificity with areas under the curve in the range of 0.78-0.98. Memory following relational encoding was a significant predictor of everyday functional competence. The RISE had acceptable psychometric properties, with the exception of floor effects in the AD group.

CONCLUSION

The RISE measures significantly predicted diagnosis and predicted everyday functional competence. The RISE offers unique advantages in the assessment of HC and individuals with preclinical AD.

Tacrolimus rescues the signaling and gene expression signature of endothelial ALK1 loss-of-function and improves HHT vascular pathology

Hereditary hemorrhagic telangiectasia (HHT) is a highly debilitating and life-threatening genetic vascular disorder arising from endothelial cell (EC) proliferation and hypervascularization, for which no cure exists. Because HHT is caused by loss-of-function mutations in bone morphogenetic protein 9 (BMP9)-ALK1-Smad1/5/8 signaling, interventions aimed at activating this pathway are of therapeutic value. We interrogated the whole-transcriptome in human umbilical vein ECs (HUVECs) and found that ALK1 signaling inhibition was associated with a specific pro-angiogenic gene expression signature, which included a significant elevation of DLL4 expression. By screening the NIH clinical collections of FDA-approved drugs, we identified tacrolimus (FK-506) as the most potent activator of ALK1 signaling in BMP9-challenged C2C12 reporter cells. In HUVECs, tacrolimus activated Smad1/5/8 and opposed the pro-angiogenic gene expression signature associated with ALK1 loss-of-function, by notably reducing Dll4 expression. In these cells, tacrolimus also inhibited Akt and p38 stimulation by vascular endothelial growth factor, a major driver of angiogenesis. In the BMP9/10-immunodepleted postnatal retina-a mouse model of HHT vascular pathology-tacrolimus activated endothelial Smad1/5/8 and prevented the Dll4 overexpression and hypervascularization associated with this model. Finally, tacrolimus stimulated Smad1/5/8 signaling in C2C12 cells expressing BMP9-unresponsive ALK1 HHT mutants and in HHT patient blood outgrowth ECs. Tacrolimus repurposing has therefore therapeutic potential in HHT.

Psychosis in Alzheimer's disease is associated with frontal metabolic impairment and accelerated decline in working memory: findings from the Alzheimer's Disease Neuroimaging Initiative

OBJECTIVE

An ascendant body of evidence suggests that Alzheimer disease with psychosis (AD+P) is a distinct variant of illness with its own genetic diathesis and a unique clinical course. Impaired frontal lobe function has been previously implicated in AD+P. The current exploratory study, presented in two parts, evaluates both the regional brain metabolic and psychometric correlates of psychosis in a longitudinal sample of subjects with AD, made available by the Alzheimer's Disease Neuroimaging Initiative (ADNI).

METHODS

In Part 1 of the study, 21 ADNI participants with AD who developed psychotic symptoms during the study but were not psychotic at baseline were matched with 21 participants with AD who never became psychotic during the study period, and mean brain [F(18)]fluorodeoxyglucose positron emission tomography (FDG-PET) Cerebral metabolic rate for glucose (CMRgl) by regions of interest (ROIs) were compared Additionally, 39 participants with active psychosis at the time of image acquisition were matched with 39 participants who were never psychotic during the study period, and mean brain FDG-PET CMRgl by sROI were compared. In Part 2 of the study, 354 ADNI participants with AD who were followed for 24 months with serial psychometric testing were identified, and cognitive performance and decline were evaluated for correlation with psychotic symptoms.

RESULTS

Part 1: There were no regional brain metabolic differences between those with AD destined to become psychotic and those who did not become psychotic. There was a significant reduction in mean orbitofrontal brain metabolism in those with active psychosis. Part 2: Over the course of study follow-up, psychosis was associated with accelerated decline in functional performance as measured by the Functional Assessment Questionnaire, the Mini-Mental State Examination, and Forward Digit Span.

CONCLUSION

In a sample drawn from the ADNI dataset, our exploratory FDG-PET findings and longitudinal cognitive outcomes support the hypofrontality model of AD+P. Focal frontal vulnerability may mediate the accelerated decline seen in AD+P.

APOE genotype modulates proton magnetic resonance spectroscopy metabolites in the aging brain

BACKGROUND

Proton magnetic resonance spectroscopy ((1)H-MRS) studies on healthy aging have reported inconsistent findings and have not systematically taken into account the possible modulatory effect of APOE genotype. We aimed to quantify brain metabolite changes in healthy subjects in relation to age and the presence of the APOE E4 genetic risk factor for Alzheimer's disease. Additionally, we examined these measures in relation to cognition.

METHODS

We studied a cohort of 112 normal adults between 50 and 86 years old who were genotyped for APOE genetic polymorphism. Measurements of (1)H-MRS metabolites were obtained in the posterior cingulate and precuneus region. Measures of general cognitive functioning, memory, executive function, semantic fluency, and speed of processing were also obtained.

RESULTS

General linear model analysis demonstrated that older APOE E4 carriers had significantly higher choline/creatine and myo-inositol/creatine ratios than APOE E3 homozygotes. Structural equation modeling resulted in a model with an excellent goodness of fit and in which the APOE × age interaction and APOE status each had a significant effect on (1)H-MRS metabolites (choline/creatine and myo-inositol/creatine). Furthermore, the APOE × age variable modulation of cognition was mediated by (1)H-MRS metabolites.

CONCLUSIONS

In a healthy aging normal population, choline/creatine and myo-inositol/creatine ratios were significantly increased in APOE E4 carriers, suggesting the presence of neuroinflammatory processes and greater membrane turnover in older carriers. Structural equation modeling analysis confirmed these possible neurodegenerative markers and also indicated the mediator role of these metabolites on cognitive performance among older APOE E4 carriers.

Semantic distance abnormalities in mild cognitive impairment: their nature and relationship to function

OBJECTIVE

The authors sought to directly examine compromises in the semantic system in mild cognitive impairment and their possible relationship to everyday functional competencies.

METHOD

Study participants were 25 patients who met criteria for amnestic mild cognitive impairment, 27 patients with mild or moderate Alzheimer's disease, and 70 healthy comparison subjects. The authors administered a novel semantic distance task in which participants make decisions about word or image stimuli that correspond to real-world entities that differ in physical size. The authors also administered a performance-based measure of everyday functional competence.

RESULTS

Participants in the mild cognitive impairment and Alzheimer's groups were consistently less accurate and slower than healthy comparison subjects in semantic decisions in which words were used as stimuli. When these participants had to make more fine-grained decisions about the semantic attribute of size, their performance in accuracy and reaction time disproportionately worsened relative to that of comparison subjects. In image-based conditions in which line drawings were used as stimuli, sensory-perceptual information (i.e., the size of the drawings themselves) had undue influence over semantic knowledge judgments in the mild cognitive impairment and Alzheimer's groups. Performance in the semantic distance task was a strong and significant predictor of everyday functional competence in the mild cognitive impairment and Alzheimer's groups.

CONCLUSIONS

This study synthesized several distinct strands in the mild cognitive impairment literature by providing evidence for 1) compromises in the semantic system in mild cognitive impairment, not confounded by overt retrieval or refractory access; 2) intrusion of perceptual information on semantic processing; and 3) a robust relation between semantic corruption and difficulties in everyday functioning.

An Open-Label Exploratory Study with Memantine: Correlation between Proton Magnetic Resonance Spectroscopy and Cognition in Patients with Mild to Moderate Alzheimer's Disease

Aim

To characterize progression of Alzheimer's disease (AD) using proton magnetic resonance spectroscopy (¹H MRS).

Methods

Eleven subjects with mild to moderate AD underwent neurocognitive testing and single-voxel ¹H MRS from the precuneus and posterior cingulate region at baseline, after 24 weeks of monotherapy with a cholinesterase inhibitor, and after another 24 weeks of combination therapy with open-label memantine and a cholinesterase inhibitor. Baseline metabolites [N-acetylaspartate (NAA), myo-inositol (mI), choline (Cho), and creatine (Cr)] and their ratios in AD subjects were compared with those of an age-matched control group of 28 cognitively normal subjects.

Results

AD subjects had significantly higher mI/Cr and lower NAA, NAA/Cr, NAA/Cho, and NAA/mI. Baseline Alzheimer's Disease Cooperative Study Activities of Daily Living (ADCS-ADL) scores significantly correlated with NAA/Cr, mI/Cr, and NAA/mI. There was an increase in mI and a decrease in NAA/mI, but no significant change in other metabolites or ratios, or neurocognitive measures, when memantine was added to a cholinesterase inhibitor.

Conclusion

Metabolite ratios significantly differed between AD and control subjects. Baseline metabolite ratios correlated with function (ADCS-ADL). There was an increase in mI and a decrease in NAA/mI, but no changes in other metabolites, ratios, or cognitive measures, when memantine was added to a cholinesterase inhibitor.

CALHM1 P86L polymorphism modulates CSF Aβ levels in cognitively healthy individuals at risk for Alzheimer's disease

The calcium homeostasis modulator 1 (CALHM1) gene codes for a novel cerebral calcium channel controlling intracellular calcium homeostasis and amyloid-β (Aβ) peptide metabolism, a key event in the etiology of Alzheimer's disease (AD). The P86L polymorphism in CALHM1 (rs2986017) initially was proposed to impair CALHM1 functionally and to lead to an increase in Aβ accumulation in vitro in cell lines. Recently, it was reported that CALHM1 P86L also may influence Aβ metabolism in vivo by increasing Aβ levels in human cerebrospinal fluid (CSF). Although the role of CALHM1 in AD risk remains uncertain, concordant data have now emerged showing that CALHM1 P86L is associated with an earlier age at onset of AD. Here, we have analyzed the association of CALHM1 P86L with CSF Aβ in samples from 203 AD cases and 46 young cognitively healthy individuals with a positive family history of AD. We failed to detect an association between the CALHM1 polymorphism and CSF Aβ levels in AD patients. Our data, however, revealed a significant association of CALHM1 P86L with elevated CSF Aβ42 and Aβ40 in the normal cohort at risk for AD. This work shows that CALHM1 modulates CSF Aβ levels in presymptomatic individuals, strengthening the notion that CALHM1 is involved in AD pathogenesis. These data further demonstrate the utility of endophenotype-based approaches focusing on CSF biomarkers for the identification or validation of risk factors for AD.

Performance-based measures of everyday function in mild cognitive impairment

OBJECTIVE

The view that everyday function is preserved in mild cognitive impairment may be problematic. The objectives of this study were to determine the magnitude of impairment in everyday function in patients with mild cognitive impairment and Alzheimer's disease using a novel sensitive performance-based measure (the UCSD Performance-Based Skills Assessment; UPSA), contrast it with use of an informant-based measure (the Alzheimer's Disease Cooperative Study-Activities of Daily Living Inventory; ADCS-ADL), and model the relationship between cognitive measures and the performance-based measure.

METHOD

Fifty cognitively normal elders, 26 patients who met criteria for amnestic mild cognitive impairment, and 22 patients who suffered from mild to moderate Alzheimer's disease were assessed on the UPSA, the ADCS-ADL, and a battery of neurocognitive tests.

RESULTS

Patients with mild cognitive impairment had significant impairments on the UPSA but not on the ADCS-ADL. The magnitude of the effect size between the cognitively healthy and the mild cognitive impairment group for the UPSA was large (d=0.86). A strong and significant relationship was observed between cognitive performances in speed (R(2)=0.37), episodic memory (R(2)=0.10), and semantic processing (R(2)=0.03) and UPSA score using multiple regression models. The psychometric properties of the UPSA were acceptable, as were its sensitivity and specificity in contrasts between cognitively normal elders and patients with mild cognitive impairment and between the latter group and patients with Alzheimer's disease.

CONCLUSIONS

These findings indicate that performance-based measures of function may be a sensitive tool in studies of Alzheimer's disease and mild cognitive impairment and suggest the need for a reconceptualization of the relationship between cognition and function in mild cognitive impairment so that they can be usefully aligned.

Alternative pathway of complement in children with diarrhea-associated hemolytic uremic syndrome

BACKGROUND AND OBJECTIVES

Diarrhea-associated hemolytic uremic syndrome (D+HUS) is a common cause of acute kidney injury in children. Mutations in alternative pathway (AP) complement regulatory proteins have been identified in severe cases of thrombotic microangiopathy, but the role of the AP in D+HUS has not been studied. Therefore, we determined whether plasma levels of markers of activation of the AP are increased in D+HUS and are biomarkers of the severity of renal injury that predict the need for dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients were randomly selected from among participants in the HUS-SYNSORB Pk trial. Plasma samples were collected on days 1, 4, 7, and 10 after enrollment and day 28 after discharge from the hospital. Levels of two complement pathway products, Bb and SC5b-9, were determined by ELISA.

RESULTS

Seventeen children (6 boys and 11 girls; age, 5.4 +/- 3.5 yr) were studied. Eight (47%) required dialysis support, and two had serious extrarenal events. On the day of enrollment, plasma levels of Bb and SC5b-9 were significantly increased in all patients compared with healthy controls (P < 0.01). The elevated concentrations normalized by day 28 after discharge. Circulating levels of complement pathway fragments did not correlate with severity of renal injury or occurrence of complications.

CONCLUSIONS

Patients with acute-onset D+HUS manifest activation of the AP of complement that is temporally related to the onset of disease and that resolves within 1 mo. Therapies to inhibit the AP of complement may be useful in attenuating the severity of renal injury and extrarenal complications.

Alternative pathway of complement in children with diarrhea-associated hemolytic uremic syndrome

BACKGROUND AND OBJECTIVES

Diarrhea-associated hemolytic uremic syndrome (D+HUS) is a common cause of acute kidney injury in children. Mutations in alternative pathway (AP) complement regulatory proteins have been identified in severe cases of thrombotic microangiopathy, but the role of the AP in D+HUS has not been studied. Therefore, we determined whether plasma levels of markers of activation of the AP are increased in D+HUS and are biomarkers of the severity of renal injury that predict the need for dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients were randomly selected from among participants in the HUS-SYNSORB Pk trial. Plasma samples were collected on days 1, 4, 7, and 10 after enrollment and day 28 after discharge from the hospital. Levels of two complement pathway products, Bb and SC5b-9, were determined by ELISA.

RESULTS

Seventeen children (6 boys and 11 girls; age, 5.4 +/- 3.5 yr) were studied. Eight (47%) required dialysis support, and two had serious extrarenal events. On the day of enrollment, plasma levels of Bb and SC5b-9 were significantly increased in all patients compared with healthy controls (P < 0.01). The elevated concentrations normalized by day 28 after discharge. Circulating levels of complement pathway fragments did not correlate with severity of renal injury or occurrence of complications.

CONCLUSIONS

Patients with acute-onset D+HUS manifest activation of the AP of complement that is temporally related to the onset of disease and that resolves within 1 mo. Therapies to inhibit the AP of complement may be useful in attenuating the severity of renal injury and extrarenal complications.

Endocannabinoids in Alzheimer's disease and their impact on normative cognitive performance: a case-control and cohort study

BACKGROUND

Neuropathological, animal, and cell culture studies point to a role for the body's own endogenous cannabinoids (eCBs) system in Alzheimer's disease (AD) pathology and treatment. To date, no published studies have investigated the potential utility of circulating eCBs as diagnostic biomarkers for AD or the impact of central eCBs on cognition.

RESULTS

In comparison with healthy controls, there were no significant differences in measured eCB concentrations in plasma samples from patients with AD. Detectable eCBs in cerebrospinal fluid (CSF) had no relationship to cognitive performance in healthy controls at risk for AD. In pooled plasma samples, an inverse correlation was observed between plasma levels of the eCB 2-AG (2-arachidonoylglycerol) and TNF-alpha (r = -0.41, p < 0.02).

CONCLUSION

These results suggest that circulating endocannabinoids do not have utility as diagnostic biomarkers for AD and do not have a robust correlation with cognitive performance. Circulating levels of 2-AG may downregulate TNF-alpha production.

Urinary podocyte mRNA excretion in children with D+HUS: a potential marker of long-term outcome

BACKGROUND

Diarrhea-associated hemolytic uremic syndrome (D+HUS) causes acute renal failure and may lead to podocyte loss. Objective. To determine if the urinary mRNA excretion of podocyte proteins is detectable in children with D+HUS and if it is a biomarker of a poor long-term outcome.

METHODS

Patients were randomly selected from participants in the SYNSORB Pk trial. Urine samples were collected daily during the first week of hospitalization. Specimens were also obtained in healthy volunteers. Synaptopodin and nephrin mRNA levels were measured using real-time PCR.

RESULTS

Fifteen children, aged 4.9+/-2.8 years, were studied. Patients were categorized based on urinary mRNA levels into normal (marker:GAPDH<or=mean + SD) or high (marker:GAPDH>mean + SD) in controls. Twelve patients (80%) had increased urinary podocyte mRNA excretion; 11 (73%) had high synaptopodin and 5 (33%) had high nephrin mRNA levels. Follow-up data were available in 13/15 patients, all of whom had normal blood pressure, urinalysis, and serum creatinine concentration.

CONCLUSION

The isolation of podocyte mRNA from routine urine samples is feasible in children with D+HUS. Most patients have podocyturia based on synaptopodin and nephrin mRNA excretion. Larger studies with extended follow-up are required to determine the relationship of these biomarkers to long-term renal prognosis in D+HUS.

Urinary neutrophil gelatinase-associated lipocalcin in D+HUS: a novel marker of renal injury

BACKGROUND

Diarrhea-associated hemolytic uremic syndrome (D+HUS) causes acute renal failure. Neutrophil gelatinase-associated lipocalcin (NGAL) is an early indicator of kidney injury.

OBJECTIVE

To determine if urinary NGAL excretion is a biomarker of severe renal injury and predicts the need for dialysis in D+HUS.

METHODS

Patients were randomly selected from among participants in the SYNSORB Pk trial. Urine samples were collected daily if available during the first week of hospitalization. NGAL levels were determined by ELISA.

RESULTS

34 children, age 5.9+/-3.9 yr, were studied; ten (29%) required dialysis. Patients were categorized based on urinary NGAL concentration within five days of hospitalization - <200 ng/ml and >or=200 ng/ml. Twenty patients (58%) had increased urinary NGAL excretion. The severity of D+HUS at enrollment was similar in the two groups. However, children with increased urinary NGAL levels had higher peak BUN and creatinine concentrations (P<0.01) and required dialysis more often, 9/20 versus 1/14 (P=0.024) compared to children with normal excretion.

CONCLUSION

The majority of patients with D+HUS have renal tubular epithelial injury, as evidenced by elevated urinary NGAL excretion. Urinary NGAL levels below 200 ng/ml within five days of hospitalization may be an adjunctive marker that defines less severe renal involvement.

Non-enteropathic hemolytic uremic syndrome: causes and short-term course

BACKGROUND

Nondiarrheal or Streptococcus pneumoniae-related hemolytic uremic syndrome (HUS) represents a heterogeneous group of disorders. This study was performed to: (1) describe the current incidence, causes, demographic features, hospital courses, and short-term outcomes of non-enteropathic HUS; (2) compare findings in patients with non-enteropathic HUS with those obtained from a contemporaneous cohort of children with enteropathic or diarrhea-associated HUS (D+ HUS) diagnosed and treated at the same clinical sites; and (3) identify clinical or laboratory features that differentiate these 2 groups and predict disease severity and the short-term outcome in patients with non-enteropathic HUS.

METHODS

Data were collected from patients screened between 1997 and 2001 for enrollment in a multicenter trial of SYNSORB Pk (SYNSORB Biotech Inc, Calgary, Alberta, Canada) in D+ HUS, but who were ineligible because of lack of a diarrhea prodrome. The following features were recorded: age; sex; ethnicity; prodromal symptoms; cause; nadir values for hemoglobin, hematocrit, and platelet count; use of dialysis; and length of hospitalization.

RESULTS

Twenty-seven of 247 children with HUS had non-enteropathic HUS (11%). Twenty-four patients (15 boys, 9 girls), whose medical records were complete and available for review, comprise the study cohort. Mean age at onset was 4.2 +/- 0.9 (SE) years. Infection caused by S pneumoniae was diagnosed in 9 patients (38%). Dialysis was performed in 17 patients (71%) for 40 +/- 27 days. Median length of hospitalization was 22 days (range, 2 to 71 days). Children with S pneumoniae-related HUS had a longer hospital stay than those with other causes of non-enteropathic HUS, but all patients with S pneumoniae-related HUS recovered kidney function. Dialysis therapy was required more often (17 of 24 versus 59 of 145 children; P = 0.025) and hospital stays were longer (median, 22 versus 9 days; P = 0.002) in children with non-enteropathic HUS compared with patients with D+ HUS who were enrolled in the SYNSORB Pk clinical trial.

CONCLUSION

(1) The incidence of non-enteropathic HUS is approximately one tenth that of D+ HUS; (2) patients with non-enteropathic HUS require dialysis therapy more often and are hospitalized more than twice as long during the acute episode compared with those with D+ HUS; (3) infection caused by S pneumoniae accounts for nearly 40% of cases of non-enteropathic HUS; and (4) although S pneumoniae-related HUS is associated with a less favorable short-term course than other types of non-enteropathic HUS or D+ HUS, the long-term prognosis for recovery of renal function appears to be good in these patients.

Effect of an oral Shiga toxin-binding agent on diarrhea-associated hemolytic uremic syndrome in children: a randomized controlled trial

CONTEXT

Diarrhea-associated hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children. Most cases are caused by an intestinal infection with Shiga toxin-producing strains of Escherichia coli.

OBJECTIVE

To determine if administration of an oral agent that binds Shiga toxin could diminish the severity of diarrhea-associated HUS in pediatric patients.

DESIGN, SETTING, AND PATIENTS

Multicenter, randomized, double-blind, placebo-controlled clinical trial of 145 children (96 experimental and 49 placebo) aged 6 months to 18 years with diarrhea-associated HUS conducted between July 27, 1997, and April 14, 2001, at 26 tertiary care pediatric nephrology centers in the United States and Canada. Trial included 2 phases, the hospital course for treatment of the acute illness and a 60-day outpatient follow-up period after discharge from the hospital.

INTERVENTION

Patients were assigned to receive the binding agent, 500 mg/kg daily, or cornmeal placebo orally for 7 days in a 2:1 randomization scheme.

MAIN OUTCOME MEASURES

Combined frequency of death or serious extrarenal events and need for dialysis in the experimental vs placebo group.

RESULTS

A total of 62 patients (43%) were male and 123 (85%) were white. The median age of the patients was 4.2 years. Most patients (59%) were transferred from other hospitals to participating sites. The severity of disease at the time of randomization was comparable in the 2 groups. The prevalence of death or serious extrarenal events was 18% and 20% in the experimental and placebo groups, respectively (P =.82). Dialysis was required in 42% of experimental and 39% of placebo groups (P =.86).

CONCLUSIONS

Oral therapy with a Shiga toxin-binding agent failed to diminish the severity of disease in pediatric patients with diarrhea-associated HUS.

Basic fibroblast growth factor among children with diarrhea-associated hemolytic uremic syndrome

Diarrhea-associated hemolytic uremic syndrome (D+HUS) is characterized by endothelial injury and activation of inflammatory cytokines. Basic fibroblast growth factor (bFGF) is an angiogenic peptide released in response to vascular damage. The plasma concentrations and urinary excretion of bFGF during the course of D+HUS were determined, in comparison with the levels of various inflammatory cytokines, and changes were correlated with clinical and laboratory features of the disease. Serial plasma and urine samples were collected from 31 children with D+HUS, during the acute (days 1 to 7 of hospitalization) and recovery (through day 60 after discharge from the hospital) phases of the disease. The patients were enrolled in the multicenter trial of SYNSORB Pk (SYNSORB Biotech, Calgary, Alberta, Canada) treatment for D+HUS. bFGF, interleukin-1alpha (IL-1alpha), IL-8, and tumor necrosis factor-alpha levels were determined with enzyme-linked immunosorbent assays. bFGF was detected in urine and plasma samples more frequently than were IL-1alpha, IL-8, and tumor necrosis factor-alpha. There was an acute increase in urinary bFGF excretion, which returned to normal during convalescence. Urinary excretion of bFGF during the acute phase was higher among patients who required dialysis, compared with those who did not (48.9 +/- 15.0 and 28.9 +/- 9.0 pg/ml, respectively; P < 0.05). Plasma bFGF concentrations were persistently elevated throughout the period of hospitalization and the follow-up period among patients with D+HUS. Urinary excretion and plasma levels of bFGF were comparable for the SYNSORB Pk-treated (n = 19) and placebo-treated (n = 12) groups. Measurements of urinary and plasma concentrations of bFGF among patients with D+HUS may be useful indices for assessment of the severity of acute renal disease and the timing and adequacy of the systemic angiogenic process during early convalescence.

Pathogenesis, treatment, and therapeutic trials in hemolytic uremic syndrome

Diarrhea-associated hemolytic uremic syndrome is one of the most common causes of acute renal failure in childhood. Nearly all cases are the result of an antecedent infection by Shiga toxin--producing strains of Escherichia coli, especially the O157:H7 serotype. Most cases occur after ingestion of contaminated meat; however, new food sources such as leaf lettuce, alfalfa sprouts, and goat's milk have been identified, and diarrhea-associated hemolytic uremic syndrome can occur after exposure to contaminated water in recreational swimming sites. Diarrhea-associated hemolytic uremic syndrome is a systemic disease with activation of a variety of inflammatory cytokines. Kidney injury may result from direct effects of the Shiga toxin on renal tubular epithelial cells as well as endothelial cells. Early diagnosis of diarrhea-associated hemolytic uremic syndrome may be expedited by the introduction of new techniques to rapidly detect toxin and microorganism in stool samples. Optimal therapy of diarrhea-associated hemolytic uremic syndrome includes intensive management of the renal failure and serious extrarenal complications that may occur during the course of disease. The role of antibiotics in prevention and amelioration of diarrhea-associated hemolytic uremic syndrome remains controversial. Experimental therapies that are undergoing evaluation in clinical trials include SYNSORB Pk (SYNSORB Biotech, Inc., Calgary, Alberta, Canada), a drug designed to bind Shiga toxin in the lumen of gastrointestinal tract. Immunization strategies are also being developed and tested. It is hoped that with continued progress in this field the incidence of diarrhea-associated hemolytic uremic syndrome in children will be substantially reduced in the coming years.

MSH receptors and the response of human A375 melanoma cells to interleukin-1 beta

alpha-Melanocyte-stimulating hormone (alpha-MSH, alpha-melanotropin) has been shown to be an inhibitory factor in many immunologic and inflammatory processes involving the cytokine interleukin-1 (IL-1). As the mechanism of the interaction between IL-1 and alpha-MSH at the receptor level is unknown, we have studied the role of MC1 melanocortin receptors in two variants of the human melanoma cell line A375 differing in their sensitivity to the cytostatic effects of IL-1 beta. Both IL-1 sensitive (A375r-) and resistant cells (A375r+) carry specific high affinity receptors for IL-1, albeit their concentration is 10-fold higher in A375r+ cells. In A375r- cells, MC1 receptors are absent or below the level for reliable detection in the binding assay. Conversion of A375r- to A375r+ cells by prolonged culture in medium not depleted of endotoxin led to the appearance of MC1 receptors (KD 0.4 +/- 0.123 nmol/l; 608 +/- 134 receptors/cell). Stable transfection of A375r- cells with the human MC1 receptor did not, however, render them resistant to the cytostatic effect of IL-1 beta on concomitant treatment with alpha-MSH or result in the production of IL-6 on treatment with IL-1 beta. Therefore, the presence of MC1 receptors on the surface of A375 cells or their binding to alpha-MSH does not seem to be a factor in cytokine resistance or IL-6 secretion. No interaction between IL-1 beta and alpha-MSH could be demonstrated at the cellular level in this melanoma cell line.

Receptor binding and biological activity of IL-1 alpha, IL-1 beta, IL-1 beta analogues and an IL-1 antagonist in A375 human melanoma cells

A receptor binding assay for IL-1 peptides on human melanoma cells of the A 375 cell line is reported. Strains differing in their sensitivity to the cytotoxic effects of IL-1 beta were compared. In both strains, binding equilibrium at temperatures between 0 degrees and 37 degrees C was reached after 4 to 8 hours. At 37 degrees C, most of the bound ligand was rapidly internalized leaving a constant level of surface receptors. Scatchard analysis at 0 degrees C revealed a single class of high affinity receptors with a similar KD in both IL-1 resistant (0.18 +/- 0.07 nM) and sensitive strains (0.14 +/- 0.06 nM) but a 10-fold difference in the number of binding sites. Whereas > 1000 binding sites per cell were regularly observed in all resistant strains, only 100-200 sites could be detected on the IL-1 sensitive cells. In displacement assays, IL-1 beta was found to be slightly more potent than IL-1 alpha in both strains. In an attempt to further characterize the IL-1 binding site in these cells, the binding characteristics and biological activity of 20 point mutations of IL-1 beta were examined. EC50 values similar to those of the wild type peptide were found in all these analogues with the exception R11S and E128K: their EC50 was increased by a factor of 10 but the biological activity was reduced 1000-fold as compared to IL-1 beta. The relative potency of an IL-1 receptor antagonist was similar to that of IL-1 beta in the displacement binding assay but a 100-fold higher concentration was required to completely block the cytotoxic effects of IL-1 beta. These results show that A375 human melanoma cells are useful for screening the binding and biological properties of analogues of the IL-1 family of peptides.

Steroidogenic activity of highly potent melanotropic peptides in the adrenal cortex of the rat

Highly purified ACTH and MSH peptides were studied in isolated rat glomerulosa and inner zone cells and their activity compared with that in an Anolis melanophore assay. While both ACTH1-39 and ACTH1-24 were almost equally potent steroidogenic peptides in the two cell types (ED50 between 1 and 4 X 10(-12) M), alpha-MSH displayed only weak steroidogenic activity. Although it was a full agonist, it was about 10(4)-fold less potent in both capsular and inner zone cells. beta-MSH (porcine) was even 10-fold less active in capsular cells than alpha-MSH, and in inner zone cells it was a partial agonist. Highly potent melanotropic peptides, such as (Nle4, D-Phe7)-alpha-MSH or cyclic (Cys4, Cys10)-alpha-MSH were either inactive or exhibited only a very slight partial steroidogenic activity in both cell types. Comparison of the activity profile of additional compounds, such as des-acetyl alpha-MSH, (Tyr(I)2)-alpha-MSH, (Trp(For)9)-alpha-MSH or (Nva12)-alpha-MSH, in the adrenocortical and pigment cell assays led to the conclusion that alpha-MSH does not exert its steroidogenic effect through a typical melanocyte-type of MSH receptor, but rather through a low affinity-type of ACTH receptor.

Inhibition of the ACTH adrenal response to stress by treatment with hydrocortisone, prednisolone and dexamethasone in the rat

16- and 4-week-old intact and adrenalectomized rats have been treated with different doses of the three glucocorticoids hydrocortisone, prednisolone and dexamethasone by gavage. The delayed feedback effect on plasma ACTH and corticosterone response to an ether stress have been assessed. Almost complete suppression of corticosterone response 20 min after an ether stress and an ACTH suppression to 20% of control values 5 min after an ether stress were observed with 25 micrograms of dexamethasone, 10 mg of prednisolone and 20 mg of hydrocortisone. Although the percent inhibition of corticosterone and ACTH response to stress was comparable, a striking dissociation of the ACTH and corticosterone release was observed in terms of absolute concentrations. A mean ACTH concentration of 462 ng/l after 25 micrograms of dexamethasone was measured together with a barely measurable corticosterone concentration of 3 micrograms%. Similarly, after 10 mg of prednisolone, the mean ACTH concentration was 404 ng/l, whilst the mean corticosterone concentration was 3 micrograms%. This dissociation demonstrates that the corticosterone concentration on its own does not necessarily reflect the ACTH release. At 4 weeks of age, the ACTH response to stress is more difficult to suppress than in adult animals. This is more obvious after adrenalectomy, where the excessive ACTH secretion was less inhibited by all glucocorticoids used. The time between the last steroid gavage and stress must be considered. In 4-week-old animals the ACTH response 16 h after 12.5 micrograms of dexamethasone was inhibited by 22%, whereas 4 h after the same dexamethasone dose the inhibition was 85%.(ABSTRACT TRUNCATED AT 250 WORDS)