Remote assessment of the Penn computerised neurocognitive battery in individuals with 22q11.2 deletion syndrome.

BACKGROUND: Neurocognitive functioning is an integral phenotype of 22q11.2 deletion syndrome relating to severity of psychopathology and outcomes. A neurocognitive battery that could be administered remotely to assess multiple cognitive domains would be especially beneficial to research on rare genetic variants, where in-person assessment can be unavailable or burdensome. The current study compares in-person and remote assessments of the Penn computerised neurocognitive battery (CNB). METHODS: Participants (mean age = 17.82, SD = 6.94 years; 48% female) completed the CNB either in-person at a laboratory (n = 222) or remotely (n = 162). RESULTS: Results show that accuracy of CNB performance was equivalent across the two testing locations, while slight differences in speed were detected in 3 of the 11 tasks. CONCLUSIONS: These findings suggest that the CNB can be used in remote settings to assess multiple neurocognitive domains.

Common and dissociable regional cerebral blood flow differences associate with dimensions of psychopathology across categorical diagnoses.

The high comorbidity among neuropsychiatric disorders suggests a possible common neurobiological phenotype. Resting-state regional cerebral blood flow (CBF) can be measured noninvasively with magnetic resonance imaging (MRI) and abnormalities in regional CBF are present in many neuropsychiatric disorders. Regional CBF may also provide a useful biological marker across different types of psychopathology. To investigate CBF changes common across psychiatric disorders, we capitalized upon a sample of 1042 youths (ages 11-23 years) who completed cross-sectional imaging as part of the Philadelphia Neurodevelopmental Cohort. CBF at rest was quantified on a voxelwise basis using arterial spin labeled perfusion MRI at 3T. A dimensional measure of psychopathology was constructed using a bifactor model of item-level data from a psychiatric screening interview, which delineated four factors (fear, anxious-misery, psychosis and behavioral symptoms) plus a general factor: overall psychopathology. Overall psychopathology was associated with elevated perfusion in several regions including the right dorsal anterior cingulate cortex (ACC) and left rostral ACC. Furthermore, several clusters were associated with specific dimensions of psychopathology. Psychosis symptoms were related to reduced perfusion in the left frontal operculum and insula, whereas fear symptoms were associated with less perfusion in the right occipital/fusiform gyrus and left subgenual ACC. Follow-up functional connectivity analyses using resting-state functional MRI collected in the same participants revealed that overall psychopathology was associated with decreased connectivity between the dorsal ACC and bilateral caudate. Together, the results of this study demonstrate common and dissociable CBF abnormalities across neuropsychiatric disorders in youth.

Characterizing social environment's association with neurocognition using census and crime data linked to the Philadelphia Neurodevelopmental Cohort.

BACKGROUND: The contribution of 'environment' has been investigated across diverse and multiple domains related to health. However, in the context of large-scale genomic studies the focus has been on obtaining individual-level endophenotypes with environment left for future decomposition. Geo-social research has indicated that environment-level variables can be reduced, and these composites can then be used with other variables as intuitive, precise representations of environment in research. METHOD: Using a large community sample (N = 9498) from the Philadelphia area, participant addresses were linked to 2010 census and crime data. These were then factor analyzed (exploratory factor analysis; EFA) to arrive at social and criminal dimensions of participants' environments. These were used to calculate environment-level scores, which were merged with individual-level variables. We estimated an exploratory multilevel structural equation model (MSEM) exploring associations among environment- and individual-level variables in diverse communities. RESULTS: The EFAs revealed that census data was best represented by two factors, one socioeconomic status and one household/language. Crime data was best represented by a single crime factor. The MSEM variables had good fit (e.g. comparative fit index = 0.98), and revealed that environment had the largest association with neurocognitive performance (ß = 0.41, p < 0.0005), followed by parent education (ß = 0.23, p < 0.0005). CONCLUSIONS: Environment-level variables can be combined to create factor scores or composites for use in larger statistical models. Our results are consistent with literature indicating that individual-level socio-demographic characteristics (e.g. race and gender) and aspects of familial social capital (e.g. parental education) have statistical relationships with neurocognitive performance.

Connectome-wide network analysis of youth with Psychosis-Spectrum symptoms.

Adults with psychotic disorders have dysconnectivity in critical brain networks, including the default mode (DM) and the cingulo-opercular (CO) networks. However, it is unknown whether such deficits are present in youth with less severe symptoms. We conducted a multivariate connectome-wide association study examining dysconnectivity with resting state functional magnetic resonance imaging in a population-based cohort of 188 youths aged 8-22 years with psychosis-spectrum (PS) symptoms and 204 typically developing (TD) comparators. We found evidence for multi-focal dysconnectivity in PS youths, implicating the bilateral anterior cingulate, frontal pole, medial temporal lobe, opercular cortex and right orbitofrontal cortex. Follow-up seed-based and network-level analyses demonstrated that these results were driven by hyper-connectivity among DM regions and diminished connectivity among CO regions, as well as diminished coupling between frontal and DM regions. Collectively, these results provide novel evidence for functional dysconnectivity in PS youths, which show marked correspondence to abnormalities reported in adults with established psychotic disorders.

Solid-organ transplantation in older adults: current status and future research.

An increasing number of patients older than 65 years are referred for and have access to organ transplantation, and an increasing number of older adults are donating organs. Although short-term outcomes are similar in older versus younger transplant recipients, older donor or recipient age is associated with inferior long-term outcomes. However, age is often a proxy for other factors that might predict poor outcomes more strongly and better identify patients at risk for adverse events. Approaches to transplantation in older adults vary across programs, but despite recent gains in access and the increased use of marginal organs, older patients remain less likely than other groups to receive a transplant, and those who do are highly selected. Moreover, few studies have addressed geriatric issues in transplant patient selection or management, or the implications on health span and disability when patients age to late life with a transplanted organ. This paper summarizes a recent trans-disciplinary workshop held by ASP, in collaboration with NHLBI, NIA, NIAID, NIDDK and AGS, to address issues related to kidney, liver, lung, or heart transplantation in older adults and to propose a research agenda in these areas.

YB-1 DNA-binding protein represses interferon gamma activation of class II major histocompatibility complex genes.

Interferon gamma (IFN-gamma) is the most potent inducer of class II major histocompatibility complex (MHC) genes. This induction is uniquely mediated by three DNA elements in the promoter region of class II MHC genes. One of these DNA elements, Y, contains an inverted CCAAT box. Previously, we have screened a lambda gt11 library for Y-binding proteins and identified the YB-1 gene. Here we provide evidence that YB-1 can repress the IFN-gamma induction of class II MHC promoter as well as the Invariant chain (Ii) gene which also contains a Y element in its promoter. This was demonstrated by cotransfecting a YB-1 expression vector with promoter-reporter gene constructs. As an alternate approach, an efficient transient transfection system was developed which resulted in a > 70% transfection efficiency. Transfection of YB-1 by this procedure resulted in the near abrogation of IFN-gamma induced HLA-DR antigen and mRNA expression. These findings show the functional suppression of class II MHC gene induction by the YB-1 protein.

Association among income loss, financial strain and depressive symptoms during COVID-19: evidence from two longitudinal studies.

BACKGROUND: The COVID-19 pandemic has major ramifications for global health and the economy, with growing concerns about economic recession and implications for mental health. Here we investigated the associations between COVID-19 pandemic-related income loss with financial strain and mental health trajectories over a 1-month course. METHODS: Two independent studies were conducted in the U.S and in Israel at the beginning of the outbreak (March-April 2020, T1; N = 4 171) and at a 1-month follow-up (T2; N = 1 559). Mixed-effects models were applied to assess associations among COVID-19-related income loss, financial strain, and pandemic-related worries about health, with anxiety and depression, controlling for multiple covariates including pre-COVID-19 income. FINDINGS: In both studies, income loss and financial strain were associated with greater depressive symptoms at T1, above and beyond T1 anxiety, worries about health, and pre-COVID-19 income. Worsening of income loss was associated with exacerbation of depression at T2 in both studies. Worsening of subjective financial strain was associated with exacerbation of depression at T2 in one study (US). INTERPRETATION: Income loss and financial strain were uniquely associated with depressive symptoms and the exacerbation of symptoms over time, above and beyond pandemic-related anxiety. Considering the painful dilemma of lockdown versus reopening, with the tradeoff between public health and economic wellbeing, our findings provide evidence that the economic impact of COVID-19 has negative implications for mental health. FUNDING: This study was supported by grants from the National Institute of Mental Health, the US-Israel Binational Science Foundation, Foundation Dora and Kirsh Foundation.

Emergent, remitted and persistent psychosis-spectrum symptoms in 22q11.2 deletion syndrome.

Individuals with 22q11.2 deletion syndrome (22q11DS) are at markedly elevated risk for schizophrenia-related disorders. Stability, emergence, remission and persistence of psychosis-spectrum symptoms were investigated longitudinally. Demographic, clinical and cognitive predictors of psychosis were assessed. Prospective follow-up over 2.8 years was undertaken in 75 individuals with 22q11DS aged 8-35 years. Mood, anxiety, attention-deficit hyperactivity disorders and psychosis-spectrum symptoms were assessed with the Kiddie-Schedule for Affective Disorders and Schizophrenia and Scale of Prodromal Symptoms (SOPS). Four domains of cognition were evaluated with the Penn Computerized Neurocognitive Battery (executive functioning, memory, complex cognition and social cognition). Psychotic disorder or clinically significant SOPS-positive ratings were consistently absent in 35%, emergent in 13%, remitted in 22% and persistent in 31% of participants. Negative symptoms and functional impairment were found to be predictive of the emergence of positive psychosis-spectrum symptoms and to reflect ongoing deficits after remission of positive symptoms. Dysphoric mood and anxiety were predictive of emergent and persistent-positive psychosis-spectrum symptoms. Lower baseline global cognition and greater global cognitive decline were predictive of psychosis-spectrum outcomes but no particular cognitive domain stood out as being significantly more discriminating than others. Our findings suggest that negative symptoms, functioning and dysphoric mood are important predictors of psychosis risk in this population.

Photophysics of GFP-related chromophores imposed by a scaffold design.

In this paper, a rigid scaffold imposes the photophysics of chromophores with a benzylidene imidazolidinone core by mimicking the ß-barrel structure of the green fluorescent protein (GFP) and its analogs. The designed artificial frameworks maintain fluorescence responses and, therefore, conformational rigidity of typically non-emissive GFP-related chromophores. To replicate a small weight percent of the chromophore inside the natural GFP, two synthetic approaches were utilized: coordinative immobilization and non-coordinative inclusion. Despite low chromophore loading in the rigid matrix, both approaches resulted in formation of photoluminescent hybrid materials. Furthermore, the rigid scaffold dictates chromophore fluorescence by replicating its behavior in solution or the solid state. The presented results open an avenue for utilization of rigid scaffolds in the engineering of materials with tunable photoluminescence profiles for a variety of practical applications.

Association between polygenic risk for schizophrenia, neurocognition and social cognition across development.

Breakthroughs in genomics have begun to unravel the genetic architecture of schizophrenia risk, providing methods for quantifying schizophrenia polygenic risk based on common genetic variants. Our objective in the current study was to understand the relationship between schizophrenia genetic risk variants and neurocognitive development in healthy individuals. We first used combined genomic and neurocognitive data from the Philadelphia Neurodevelopmental Cohort (4303 participants ages 8-21 years) to screen 26 neurocognitive phenotypes for their association with schizophrenia polygenic risk. Schizophrenia polygenic risk was estimated for each participant based on summary statistics from the most recent schizophrenia genome-wide association analysis (Psychiatric Genomics Consortium 2014). After correction for multiple comparisons, greater schizophrenia polygenic risk was significantly associated with reduced speed of emotion identification and verbal reasoning. These associations were significant by age 9 years and there was no evidence of interaction between schizophrenia polygenic risk and age on neurocognitive performance. We then looked at the association between schizophrenia polygenic risk and emotion identification speed in the Harvard/MGH Brain Genomics Superstruct Project sample (695 participants ages 18-35 years), where we replicated the association between schizophrenia polygenic risk and emotion identification speed. These analyses provide evidence for a replicable association between polygenic risk for schizophrenia and a specific aspect of social cognition. Our findings indicate that individual differences in genetic risk for schizophrenia are linked with the development of aspects of social cognition and potentially verbal reasoning, and that these associations emerge relatively early in development.

Blocked ETA receptors prevent ischemia and reperfusion injury in rat lungs.

The effects of endothelin (ET)-A (ETA)- and ETB-receptor agonist and antagonists were studied in isolated buffer-perfused rat lungs subjected to 45 min of ischemia followed by 105 min of reperfusion (I/R). For the I/R group after 30 and 90 min of reperfusion, the Kfc had increased three- and fivefold above control values, respectively (P < 0.01), and the number of circulating neutrophils in the perfusate decreased by 65 +/- 7.65%. Both an ETA-receptor antagonist (BQ-610) and an ETAB-receptor antagonist (PD-156707-0015) given before the ischemic period protected the lung endothelial barrier from injury associated with I/R. Also, these compounds attenuated the I/R-induced neutrophil accumulation in the lung (31.94 +/- 4.16 and 34.38 +/- 1.05%, respectively; P < 0.01 compared with I/R). Neither an ETB-receptor agonist (IRL-1620) nor an ETB-receptor antagonist (IRL-1038) affected the I/R-induced endothelial injury. In addition, they did not alter the number of circulating polymorphonuclear cells during I/R. ET-1 administration alone caused a dose-dependent increase in pulmonary arterial pressure, but no measurable increase in microvascular permeability occurred. We conclude that ET-1 is involved in I/R-induced lung endothelial injury and speculate that it acts in concert with some other coactivator(s), most likely platelet-activating factor, through ETA receptors. This mechanism requires polymorphonuclear leukocyte activation with subsequent release of oxygen radicals and/or expression of adhesive molecules on the neutrophil surface.

ATP-sensitive K+ channels are not involved in ischemia-reperfusion lung endothelial injury.

The role of ATP-sensitive K+ channels (KATP) in ischemia and reperfusion (I/R) was studied in isolated rat lungs. I/R produced a sixfold increase in endothelial permeability as measured by the capillary filtration coefficient. Cromakalim (10 microM) given at 46 min after reperfusion reversed the filtration coefficient increase. This effect was not blocked by either a protein kinase A inhibitor (adenosine-3',5'-cyclic monophosphothioate; 100 microM) or an adenosine antagonist [8-(p-sulfophenyl)-theophylline; 20 microM]. Cromakalim given before ischemia or at the beginning of reperfusion protected the endothelial barrier from injury. Glibenclamide (500 microM) given before the ischemic period, at the beginning of reperfusion, or 46 min after reperfusion did not alter the changes in microvascular permeability produced by I/R. Glibenclamide blocked the ability of cromakalim to reverse endothelial damage but not the ability of either isoproterenol (10 microM) or an adenosine A2-receptor agonist, CGS-21680 (300 nM). We conclude that opening of KATP channels does not produce endothelial injury in I/R. The activation of KATP channels can both protect against and reverse the endothelial damage associated with I/R. This novel mechanism(s) is independent from known pathways that employ cAMP-protein kinase system and adenosine.

Effect of nitric oxide and cyclooxygenase products on vascular resistance in dog and rat lungs.

Pulmonary vascular resistance decreases with increased cardiac output. Because nitric oxide (NO) and prostacyclin are potent vasodilators that are released with increased shear stress, their roles in the control of pulmonary vascular pressure were evaluated using isolated blood-perfused rat and dog lungs. Lungs were perfused with an initial arteriovenous pressure gradient (Ppa-Ppv) of 15 cmH2O; Ppa and Ppv were increased by the same amount, and the flow was measured. In rat lung (n = 6), the NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) decreased pulmonary blood flow by approximately 50% at the same pressure (P < 0.05), whereas the cyclooxygenase inhibitor indomethacin (n = 6) had no effect. In dog lungs (n = 6), indomethacin decreased pulmonary blood flow by approximately 50% at the same pressure gradient (P < 0.05), whereas L-NAME (n = 6) had no effect. Furthermore, the flow increase that occurs as venous and arterial pressures are elevated together (so that Ppa-Ppv is constant) was inhibited by L-NAME in rat lungs and by indomethacin in dog lungs (P < 0.05 for each). Plasma guanosine 3',5'-cyclic monophosphate (cGMP) rose with increased absolute pressure in rat lung [from 71 +/- 17 to 274 +/- 104 pM (P < 0.05)], and this increase was blocked by L-NAME. Plasma cGMP was unchanged in dog lung, but the ratio of prostacyclin to thromboxane tended to be higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Adhesion molecules contribute to ischemia and reperfusion-induced injury in the isolated rat lung.

Leukocyte adherence to the endothelium after ischemia and reperfusion contributes to microvascular injury in most organs. The purpose of this study was to evaluate the leukocyte and endothelial cell adhesion molecules involved with ischemia-reperfusion (I/R)-induced pulmonary microvascular injury in the isolated rat lung. After 45 min of ischemia and 30 min of reperfusion, microvascular permeability was significantly increased and lung retention of leukocytes occurred. Pretreatment with monoclonal antibodies against the leukocyte adhesion molecule CD18 or the endothelial cell adhesion molecules intercellular adhesion molecule 1 and P-selectin significantly attenuated the I/R-induced permeability increase and lung sequestration of neutrophils, mononuclear leukocytes, and eosinophils. In contrast, immunoneutralization of the rat leukocyte adhesion molecule L-selectin neither protected against the I/R-induced permeability increase nor prevented lung sequestration of neutrophils and eosinophils. We conclude that leukocyte adherence in the pulmonary, microvasculature and subsequent permeability increase after I/R is dependent on the integrin CD18, its endothelial cell ligand intercellular adhesion molecule 1, and the endothelial cell rolling factor P-selectin but not the leukocyte rolling factor L-selectin.

Muscarinic agonists and antagonists cause vasodilation in isolated rat lung.

The present study investigated the ability of atropine and different muscarinic receptor subtypes to affect acetylcholine (ACh)-induced bronchoconstriction and vasodilation in the isolated rat lung model. ACh (10(-7) M) given after U-46619 decreased total (RT), precapillary, and postcapillary vascular resistances and increased peak airway pressure. Atropine (20 microM) decreased RT and precapillary and postcapillary vascular resistances and blocked ACh-induced increases in peak airway pressure. The M1-selective agonist McN-A-343 (1.3 x 10(-5) M) decreased RT from 40.27 +/- 2.98 to 29.20 +/- 2.81 cmH2O.l-1.min-100 g lung wt (P = 0.01), and ACh caused no further dilation. The M1-selective antagonist pirenzepine (1.6 x 10(-6) M) blocked ACh-induced vasodilation. The M2-selective antagonist gallamine (7.5 x 10(-7) M) decreased RT from 45.50 +/- 3.19 to 34.86 +/- 1.25 cmH2O.l-1.min.100 g lung wt (P < 0.05), and after gallamine, ACh further decreased RT to 28.59 +/- 1.75 cmH2O.l-1.min.100 g lung wt (P < 0.01). Neither the selective muscarinic agonists nor antagonists affected peak airway pressures. We conclude that ACh-induced vasodilation in isolated rat lungs preconstricted with U-46619 is mediated by M1 receptors. Atropine-induced vasodilation in this model is mediated through the inhibition of the M2 receptor. We postulate that this represents either a blockade of postganglionic receptors, permitting release of vasodilator substances from local nerve terminals, or a direct vasodilatory effect on the vascular smooth muscle.

Adenosine prevents PMA-induced lung injury via an A2 receptor mechanism.

Previous studies indicate that adenosine attenuates phorbol myristate acetate-(PMA) induced canine lung injury, but the mechanism has not been explained. To evaluate adenosine's protective mechanism, isolated and blood-perfused dog lungs were challenged by PMA (50 micrograms) under control conditions and after both pre- and post-treatment with adenosine and pretreatment with 2-chloro-N6-cyclopentyladenosine (CCPA), 2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamido adenosine (CGS 21680C), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; PD-116948), or isoproterenol. Injury was assessed by measurement of the capillary filtration coefficient (Kf,c), and pulmonary vascular resistance was measured. PMA increased the Kf,c (0.170 +/- 0.015 to 1.030 +/- 0.167 ml.min-1.cmH2O-1.100 g lung wet wt-1) and the total pulmonary vascular resistance (18.2 +/- 3.8 to 110.2 +/- 60.8 cmH2O.l-1.min.100 g lung wet wt). Pretreatment with adenosine, A2 agonist, A1 antagonist, and isoproterenol blocked the increase in Kf,c induced by PMA. These agents also slightly attenuated the resistance increase induced by PMA, with the exception of the A1 antagonist, which completely prevented the resistance increase (24.3 +/- 7.8 to 23.4 +/- 8.1 cmH2O.l-1.min.100 g lung wet wt). The A1 agonist also slightly attenuated the increase in Kf,c (0.174 +/- 0.022 to 0.486 +/- 0.128 ml.min-1.cmH2O-1.100 g lung wet wt-1) and did not affect the resistance increase. Posttreatment with adenosine did not significantly affect the changes induced by PMA. These data show that PMA-induced increases in capillary permeability in the isolated blood-perfused dog lung can be blocked by pretreatment with adenosine, which binds the adenosine A2 receptors.

Vascular permeability and epithelial transport effects on lung edema formation in ischemia and reperfusion.

To determine the role of various Na+ transport systems in the edema fluid accumulation after ischemia and reperfusion in the lung, we evaluated the effect of amiloride (a Na+ channel blocker), ouabain (a Na(+)-K(+)-adenosinetriphosphatase blocker), and phloridzin (a Na(+)-glucose cotransport blocker) in isolated rat lungs. Ischemia and reperfusion (I/R) significantly increased the edema accumulation, with the wet-to-dry weight ratios increasing to 10.14 +/- 0.58 from 6.03 +/- 0.05 in control lungs (P < 0.04). Amiloride significantly augmented the amount of edema fluid (wet-to-dry weight ratio 12.26 +/- 0.77), and ouabain further increased the amount of edema (wet-to-dry weight ratio 18.58 +/- 1.00). Phloridzin did not significantly affect edema formation associated with I/R. Isoproterenol decreased the amount of edema formation in the presence and absence of amiloride. This occurred because the endothelial permeability as assessed by filtration coefficient was restored to normal values and less edema formed. The present study indicates that Na+ channels and Na(+)-K(+)-adenosinetriphosphatase, components of the active Na+ absorption transport system, are very important in opposing edema fluid accumulation in rat lungs subjected to I/R injury and operate as an edema safety factor. However, if the endothelial damage associated with I/R is allowed to persist, then the transport processes, even if operative, are insufficient to prevent continuous edema accumulation.

Adenosine A2 receptors reverse ischemia-reperfusion lung injury independent of beta-receptors.

To evaluate the adenosine systems ability to reverse the endothelial damage produced by ischemia and reperfusion (I/R), we studied several different selective adenosine-receptor agonists and antagonists, a protein kinase A inhibitor, and a beta-adrenoreceptor antagonist in isolated buffer-perfused rat lungs. I/R (45 min/105 min) produced a sixfold increase in endothelial permeability as measured by the capillary filtration coefficient. Both a selective A2-receptor agonist (CGS-21680, 300 nM) and a beta-receptor agonist (isoproterenol, 10 microM) reversed the increased microvascular permeability. A nonselective adenosine-receptor antagonist (SPT, 20 microM) and a selective A1-receptor antagonist (DPCPX, 10 nM) had no effect on increased microvascular permeability. Also, isoproterenol and CGS-21680 reversed the damage being introduced after a selective A1-receptor agonist (CCPA, 100 nM). The nonspecific adenosine A1- and A2-receptor agonist NECA (12 nM) appeared to desensitize the A2 receptors and a protein kinase A inhibitor, adenosine-3',5'-cyclic monophosphothioate (Rp-cAMPS, 100 microM), blocked the reversal of endothelial damage by isoproterenol or A2-receptor agonist. Propranolol (100 microM) blocked the effect of isoproterenol but not the effect of CGS-21680. From this study we conclude that A2-receptor activation reverses endothelial damage associated with I/R by a mechanism independent of beta-receptors or Gi protein. However, a protein kinase A-3',5',-cyclic adenosine monophosphate pathway is activated by both the adenosine systems and beta-receptor activation.

Determination of the vascularity of the femoral head with technetium 99m-sulphur-colloid.

The results of technetium 99m-sulphur-colloid scans performed at the Los Angeles County-University of Southern California Medical Center and Rancho Los Amigos Hospital to assess the vascular status of the femoral head after sixty-five displaced and thirty undisplaced fractures of the neck of the femur and forty-four traumatic hip dislocations as well as in fifty patients with idiopathic ischemic necrosis of seventy femoral heads were evaluated by histological and clinical examination after follow-up of two years or more. The accuracy of the scan as corroborated by the histological findings and clinical results was 95 per cent. The method is safe, reliable, accurate, and simple in contrast to other methods which have disadvantages related primarily to technical complexities, difficulty in interpretation, and expense.