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Wadenberg MG, Sills TL, Fletcher PJ, Kapur S. Antipsychoticlike effects of amoxapine, without catalepsy, using the prepulse inhibition of the acoustic startle reflex test in rats. Biol Psychiatry 2000; 47:670-6. [PMID: 10745061 DOI: 10.1016/s0006-3223(99)00267-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND The dibenzoxazepine amoxapine was introduced as an antidepressant but has shown antipsychoticlike activity in a number of animal screening tests. A recent positron emission tomography study showed a 5-HT(2)/D(2) receptor occupancy profile of amoxapine that is very similar to that of established atypical antipsychotics. Schizophrenics display deficits in sensory gating mechanisms, such as prepulse inhibition (PPI) of the acoustic startle reflex. A similar deficit can be produced by dopamine (DA) and by 5-HT(2A/C) receptor agonists in rats. Antipsychotic compounds reverse this effect. METHODS Effects of amoxapine on apomorphine- or 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-induced disruption of PPI were studied in adult male Sprague-Dawley rats. The extrapyramidal side effect (EPS) liability of amoxapine was assessed using the inclined grid catalepsy (CAT) test. Statistical analyses were performed by analysis of variance (ANOVA) for fully repeated measures (PPI) and by the Kruskal-Wallis one-way ANOVA by ranks (CAT). RESULTS Apomorphine (0.5 mg/kg) produced a significant reduction in PPI compared with the case of rats in the saline control group. Pretreatment with amoxapine (10 mg/kg) significantly attenuated the apomorphine-induced disruption of PPI. DOI (0.5 mg/kg) significantly reduced PPI compared with saline controls. Pretreatment with amoxapine (5 or 10 mg/kg) produced a significant attenuation of the DOI-induced disruption of PPI. Amoxapine by itself did not alter PPI. Amoxapine (5 or 10 mg/kg) did not produce CAT. CONCLUSIONS The DA D(2)/5-HT(2) receptor antagonist amoxapine produced an antipsychoticlike reversal of both apomorphine- and DOI-induced disruption of PPI. Furthermore, the same doses of amoxapine that reversed disruption of PPI did not produce CAT. The results confirm and lend further support to the results of previous studies on amoxapine, suggesting that amoxapine might possess antipsychotic activity with little propensity for producing EPS.
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Kapur S, Zipursky R, Jones C, Remington G, Houle S. Relationship between dopamine D(2) occupancy, clinical response, and side effects: a double-blind PET study of first-episode schizophrenia. Am J Psychiatry 2000; 157:514-20. [PMID: 10739409 DOI: 10.1176/appi.ajp.157.4.514] [Citation(s) in RCA: 698] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Since all antipsychotics block dopamine D(2) receptors, the authors investigated how well D(2) receptor occupancy in vivo predicts clinical response, extrapyramidal side effects, and hyperprolactinemia. METHOD In a double-blind study, 22 patients with first-episode schizophrenia were randomly assigned to 1.0 or 2. 5 mg/day of haloperidol. After 2 weeks of treatment, D(2) receptor occupancy was determined with [(11)C]raclopride and positron emission tomography, and clinical response, extrapyramidal side effects, and prolactin levels were measured. Patients who showed adequate responses continued taking their initial doses, those who did not respond had their doses increased to 5.0 mg/day, and evaluations were repeated at 4 weeks for all patients. RESULTS The patients showed a wide range of D(2) occupancy (38%-87%). The degree of receptor occupancy predicted clinical improvement, hyperprolactinemia, and extrapyramidal side effects. The likelihood of clinical response, hyperprolactinemia, and extrapyramidal side effects increased significantly as D(2) occupancy exceeded 65%, 72%, and 78%, respectively. CONCLUSIONS The study confirms that D(2) occupancy is an important mediator of response and side effects in antipsychotic treatment. The data are consistent with a "target and trigger" hypothesis of antipsychotic action, i.e., that the D(2) receptor specificity of antipsychotics permits them to target discrete neurons and that their antagonist properties trigger within those neurons intracellular changes that ultimately beget antipsychotic response. While limited to haloperidol, the relationship between D(2) occupancy and side effects in this study helps explain many of the observed clinical differences between typical and atypical antipsychotics.
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Kapur S, Wadenberg ML, Remington G. Are animal studies of antipsychotics appropriately dosed? Lessons from the bedside to the bench. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2000; 45:241-6. [PMID: 10779880 DOI: 10.1177/070674370004500302] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Animal models are crucial for understanding the mechanism of action of antipsychotics. However, the dose of an antipsychotic in animal studies is often arbitrarily chosen, with haloperidol 1 mg/kg being a rather common standard. Recent clinical positron emission tomography (PET) studies in patients show all antipsychotics to block dopamine D2 receptors, and most are effective at doses that lead to 60% to 80% D2 occupancy. When occupancy exceeds 80%, the incidence of side effects rises sharply. To use this "bedside" information to inform the "bench," we measured D2 occupancy in rats using a method similar in principle to the [11C]-raclopride PET method in humans. We found that: 1) as in humans, haloperidol is effective in animal models of antipsychotic action when D2 occupancy > 70% and leads to effects in models of extrapyramidal side effects when D2 occupancy is > 80%; 2) very low doses, 0.06 mg/kg/sc, cause acute D2 occupancy of 75%; 3) and even doses that acutely saturate D2 receptors give little D2 occupancy after 24 hours due to the very short half-life of haloperidol in rats (2.5 hours versus 24 hours in humans). We conclude that most previous animal studies of antipsychotics have used doses giving rise to inappropriately high acute D2 occupancy and inappropriately low D2 occupancy between doses. We exemplify how this dosing confounder could lead to inappropriate conclusions. Data from the bedside translated to the bench--using D2 occupancy as a mediating variable--will lead to more valid animal models.
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Rastogi S, Kapur S, Salhan S, Mittal A. Chlamydia trachomatis infection in pregnancy: risk factor for an adverse outcome. Br J Biomed Sci 2000; 56:94-8. [PMID: 10695048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
A cohort of 122 pregnant women attending the hospital antenatal clinic in northern India were studied to determine the prevalence of genital chlamydial infection, and any adverse effect on the pregnancy. Endocervical swabs were taken at > 12 weeks of pregnancy and cultured for Chlamydia trachomatis. Twenty-six (21.3%) pregnant women were found to be infected with C. trachomatis. The mean age, gravidity and parity were significantly higher (25.03 vs 23.6 years, 1.88 vs 1.72 and 0.92 vs 0.68 respectively [P < 0.005]) in women from whom C. trachomatis was isolated. Follow-up was possible in 87 women who delivered in the hospital. There was increased incidence of still-birth, prematurity and low birth-weight in the C. trachomatis-positive women (16.6% vs 5.7%, 26.6% vs 18.4% and 26.6% vs 23.0%), and these differences were statistically significant (P < 0.5, P < 0.5 and P < 0.05 respectively). The results suggest a definite need for C. trachomatis screening on a wider scale, both in different risk groups of asymptomatic antenatal women and in neonates, to confirm these findings.
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Fitzgerald PB, Kapur S, Remington G, Roy P, Zipursky RB. Predicting haloperidol occupancy of central dopamine D2 receptors from plasma levels. Psychopharmacology (Berl) 2000; 149:1-5. [PMID: 10789875 DOI: 10.1007/s002139900333] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Positron emission tomography (PET) is increasingly being used to study dopamine receptor occupancy and the clinical effects of antipsychotic medication. Dopamine D2 receptor occupancy has been shown to predict several clinical effects of antipsychotic medication including therapeutic response, motor and endocrine side-effects. Plasma levels may be used as a surrogate marker for central occupancy if the relationship between these two measures may be accurately described. This study was designed to test the capacity of a previously derived relationship equation (%D2 occupancy=plasma level/ED50+plasma level, where ED50= 0.40 ng/ml) to predict striatal D2 occupancy from plasma level. Twenty-one patients receiving treatment with low dose haloperidol underwent a 11C-raclopride PET scan to measure D2 occupancy. The D2 occupancy levels were accurately predicted by use of the previously generated equation with only a small degree of error (3.89% CI 0.45-7.33). Predicted and measured D2 occupancy values correlated closely (Pearson's r=0.864, P=0.003). The study indicates that reliable prediction of D2 occupancy from plasma levels is possible. This provides a potentially useful surrogate measure of D2 occupancy for research and possibly clinical practice, as the routine use of PET to measure occupancy levels is not feasible.
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Iidaka T, Anderson ND, Kapur S, Cabeza R, Craik FI. The effect of divided attention on encoding and retrieval in episodic memory revealed by positron emission tomography. J Cogn Neurosci 2000; 12:267-80. [PMID: 10771411 DOI: 10.1162/089892900562093] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The effects of divided attention (DA) on episodic memory encoding and retrieval were investigated in 12 normal young subjects by positron emission tomography (PET). Cerebral blood flow was measured while subjects were concurrently performing a memory task (encoding and retrieval of visually presented word pairs) and an auditory tone-discrimination task. The PET data were analyzed using multivariate Partial Least Squares (PLS), and the results revealed three sets of neural correlates related to specific task contrasts. Brain activity, relatively greater under conditions of full attention (FA) than DA, was identified in the occipital-temporal, medial, and ventral-frontal areas, whereas areas showing relatively more activity under DA than FA were found in the cerebellum, temporo-parietal, left anterior-cingulate gyrus, and bilateral dorsolateral-prefrontal areas. Regions more active during encoding than during retrieval were located in the hippocampus, temporal and the prefrontal cortex of the left hemisphere, and regions more active during retrieval than during encoding included areas in the medial and right-prefrontal cortex, basal ganglia, thalamus, and cuneus. DA at encoding was associated with specific decreases in rCBF in the left-prefrontal areas, whereas DA at retrieval was associated with decreased rCBF in a relatively small region in the right-prefrontal cortex. These different patterns of activity are related to the behavioral results, which showed a substantial decrease in memory performance when the DA task was performed at encoding, but no change in memory levels when the DA task was performed at retrieval.
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Kapur S, Seeman P. Antipsychotic agents differ in how fast they come off the dopamine D2 receptors. Implications for atypical antipsychotic action. J Psychiatry Neurosci 2000; 25:161-6. [PMID: 10740989 PMCID: PMC1408069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
RATIONALE AND OBJECTIVE While the blockade of dopamine D2 receptors are necessary for antipsychotic action, antipsychotic agents differ nearly a thousand-fold in their affinity for the D2 receptor. This affinity is determined by the rate at which the antipsychotic agent binds to (kon) and the rate at which it dissociates from (koff) the D2 receptors. The objective of this study was to determine the relationship between kon, koff and the affinity (Ki) of antipsychotic agents for the D2 receptors, with particular reference to typical and atypical antipsychotic agents. DESIGN The koff of several typical as well as atypical antipsychotic agents (nemonapride, spiperone, haloperidol, chlorpromazine, raclopride, olanzapine, sertindole, clozapine and quetiapine) was measured in vitro using the 3H-radiolabelled analogues of these drugs. The affinity of these drugs for the D2 receptor was determined by competition with 3H-raclopride in vitro. The kon was derived from values of affinity and ++koff. MAIN OUTCOME MEASURES kon, koff, and the Ki of antipsychotic drugs. RESULTS The range of affinity values was similar to that conventionally accepted (0.025-155 nmol/L). The koff values varied a thousand-fold from 0.002 to 3.013 min-1, with relatively little variation in kon. The rate at which antipsychotic agents come off the receptor (koff) accounted for 99% of the variation in their affinity for the D2 receptor; differences in kon did not account for differences in affinity. CONCLUSIONS The differences in the affinity of antipsychotic agents are entirely determined by how fast they come off the D2 receptor. These differences in koff may lead to functionally different kinds of dopamine blockade. Drugs with a higher koff will be faster in blocking receptors, and once blocked, will provide more access to surges in dopamine transmission. Since atypical drugs show a lower affinity and a faster dissociation, a higher koff for the D2 receptor is proposed as a mechanism for "atypical" antipsychotic effect.
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Polyak MM, Arrington B, Gage F, Kapur S, Stubenbord WT, Kinkhabwala M. Supplemental reduced glutathione during cold ischemia does not improve early renal allograft function. Transplant Proc 2000; 32:32-4. [PMID: 10700956 DOI: 10.1016/s0041-1345(99)00864-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Polyak MM, Arrington BO, Stubenbord WT, Boykin J, Brown T, Jean-Jacques MA, Estevez J, Kapur S, Kinkhabwala M. The influence of pulsatile preservation on renal transplantation in the 1990s. Transplantation 2000; 69:249-58. [PMID: 10670635 DOI: 10.1097/00007890-200001270-00010] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Unlike simple cold storage (CS), pulsatile machine preservation (MP) of kidneys for transplantation permits pharmacologic manipulation of the perfusate and aids in the pretransplant assessment of the kidney graft. These characteristics of MP may have importance in the era of increasing use of extended criteria donor kidneys. The overall aim of this article is to critically assess practices at our preservation unit with respect to graft function. Specific aims are to (1) compare the influence of MP versus CS on graft function, (2) determine which pretransplant variables have significance in pretransplant assessment, and (3) determine whether pharmacologic manipulation during MP is advantageous. METHODS There were 650 consecutive kidneys preserved in our laboratory between January 1, 1993 and March 1, 999, by either MP or CS. All MP kidneys were preserved by continuous hypothermic pulsatile perfusion using Belzer-MPS or Belzer II solution. Perfusion parameters and electrolytes were measured serially during pulsatile perfusion. All CS kidneys were stored in University of Wisconsin solution. All kidneys obtained from donors exhibiting extended criteria features underwent pretransplant frozen section biopsies. Transmission electron microscopy (EM) was performed on a subset of kidneys undergoing pharmacologic manipulation. Four agents were assessed prospectively for their ability to influence MP characteristics when added to perfusate: PGE1, trifluoperazine, verapamil, and papaverine. RESULTS MP was associated with improved immediate, 1-, and 2-year graft function and reduced length of initial hospital stay when compared with CS grafts. Changes in the machine perfusion variables flow and resistance, and the [Ca++] in perfusate, were significantly associated with delayed graft function (DGF) after the transplant. Biopsy information was not predictive of DGF. The addition of PGE1 to perfusate improved MP characteristics, reduced the release of [Ca++] into perfusate, and ameliorated mitochondrial ischemic injury in transmission EM images. Early graft function was improved in the presence of PGE1+MP, compared with function in the presence of other pharmacologic agents or CS alone. CONCLUSIONS MP is associated with improved early and long term renal function. Moreover, PGE1 augments MP in improving graft function. The combination of MP+PGE1 may be important in optimizing the ability to use extended donor criteria kidneys and, thereby, improve the overall efficiency of cadaveric renal transplantation.
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Polyak MM, Arrington BO, Kapur S, Stubenbord WT, Kinkhabwala M. Donor treatment with phentolamine mesylate improves machine preservation dynamics and early renal allograft function. Transplantation 2000; 69:184-6. [PMID: 10653402 DOI: 10.1097/00007890-200001150-00033] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND It has been suggested that pharmacologic conditioning of the donor before organ procurement may protect the renal allograft from injuries associated with the cold ischemic period. We compared the administration of two vasoactive agents before organ procurement to: (1) determine their influence on machine perfusion characteristics and (2) determine their impact on delayed graft function (DGF) in transplanted renal allografts. METHODS Between January 1997 and December 1998, 150 kidneys were procured from heart-beating donors and preserved in our laboratory by machine perfusion (MP) or cold storage (CS). The following vasoactive agents were randomly administered to the donor 5 min before aortic cross clamp: phentolamine mesylate (PM) or hydralazine (H). The control groups received no donor conditioning. Kidneys were grouped as follows: (1) MP+PM, (2) MP+H, (3) MP, (4) CS+PM, (5) CS+H, (6) CS. 10 mg PM/50 kg donor weight was administered to the PM groups and 20 mg H/50 kg donor weight was administered to the H groups. DGF was defined as the need for dialysis within the first 7 days after the transplant. RESULTS MP+PM increased renal flow by 12% and decreased renal resistance by 18% compared with the MP+H group, and increased renal flow by 23% and decreased renal resistance by 30% compared with the MP group. Moreover, the MP+PM group was associated with improved early allograft function. CONCLUSIONS Donor treatment with PM immediately before aortic cross-clamp is associated with improved machine perfusion dynamics (renal flow and renal resistance) and lower incidence of DGF compared with donor treatment with H or no treatment. Moreover, MP of renal allografts was associated with improved early function compared with CS grafts.
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Abstract
On the heels of clozapine, we now have a number of newer agents (risperidone, olanzapine, quetiapine, sertindole, and ziprasidone). Are they all the same? What are the differences? How do we best understand them? In this article we review current clinical evidence to compare these issues on four measures of atypicality: EPS, prolactin elevation, superior efficacy in refractory/positive symptoms and efficacy against negative symptoms. All the newer agents are superior on EPS and, with the exception of risperidone, avoid prolactin elevation. Clozapine shows the most convincing efficacy in refractory schizophrenia, although comparative data concerning risperidone's benefit in this respect are also emerging. It is unclear, however, whether any of the agents produce a greater effect than conventional antipsychotics against positive symptoms in responsive patients. Both clozapine and olanzapine have demonstrated superior efficacy against negative symptoms, although it remains controversial whether this is an effect on primary or secondary symptoms. The precise pharmacologic mechanisms underlying "atypicality" remain unclear, but several conceptual frameworks are highlighted that characterize, and perhaps differentiate, these newer agents.
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Fitzgerald PB, Kapur S, Caligiuri MP, Jones C, Silvestri S, Remington G, Zipursky RB. Instrumentally detected changes in motor functioning in patients with low levels of antipsychotic dopamine D2 blockade. Neuropsychopharmacology 2000; 22:19-26. [PMID: 10633487 DOI: 10.1016/s0893-133x(99)00081-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Extrapyramidal side-effects (EPSE) of antipsychotic medication are related to the occupancy of dopamine D2 receptors and there appears to be a threshold of D2 occupancy below which clinically EPSE are unlikely to occur. It is unclear whether there are motor changes produced by 'subthreshold' levels of D2 occupancy that are not detectable by clinical examination. This study was designed to investigate whether a number of electromechanical instrumental techniques could detect 'subthreshold' motor changes and whether these changes correlate with dopamine D2 occupancy as measured by [11C]-raclopride PET scan. Twenty medication naïve patients were studied before and during treatment with low dose haloperidol. Instrumental techniques detected an asymmetrical worsening in motor function with drug treatment despite the failure of the group to experience significant EPSE. These changes did not correlate with D2 occupancy and measurements of rigidity, tremor, and bradykinesia did not closely inter-correlate.
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Polyak MM, Arrington BO, Kapur S, Stubenbord WT, Kinkhabwala M. Calcium ion concentration of machine perfusate predicts early graft function in expanded criteria donor kidneys. Transpl Int 1999; 12:378-82. [PMID: 10552005 DOI: 10.1007/s001470050243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pulsatile preservation offers the advantage of pretransplant assessment of donor kidneys. Selected electrolyte concentrations of machine perfusate were measured over time in order to: (1) describe electrolyte changes in perfusate during the pulsatile preservation of expanded-criteria donor (ECD) kidneys, and (2) to assess the prognostic significance of these characteristics to early graft function. One hundred and fifty ECD kidneys were preserved in our laboratory between 1 January 1995 and 11 January 1997. ECD kidneys were defined as those requiring pretransplant biopsy. Kidneys were grouped by the presence or absence of delayed graft function (DGF), and perfusion parameters were measured every hour during pulsatile perfusion. All kidneys were preserved by continuous hypothermic pulsatile perfusion using Belzer II solution. Renal flow is decreased and renal resistance is increased in the presence of DGF in machine-preserved ECD kidneys. In addition, ionized calcium concentration of the machine perfusate is significantly elevated in the DGF group compared with the No DGF group (0.091 vs 0.054, P = 0.0016). The incidence of DGF is significantly lower in the ECD kidney. Among the pretransplant variables of donor characteristics, perfusion parameters and histology, perfusion parameters are highly predictive of early graft function. In addition, we found that ionized calcium concentration in the perfusate is significantly elevated in kidneys exhibiting DGF, which may have implications for assessing the suitability of donor kidneys for transplantation.
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Polyak MM, Arrington BO, Stubenbord WT, Kapur S, Kinkhabwala M. Prostaglandin E1 influences pulsatile preservation characteristics and early graft function in expanded criteria donor kidneys. J Surg Res 1999; 85:17-25. [PMID: 10383833 DOI: 10.1006/jsre.1999.5652] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Unlike simple cold storage, machine preservation allows dynamic assessment and manipulation of the donor organ prior to transplantation. We prospectively compared the effects of five pharmacological agents added to the perfusate during machine preservation of expanded criteria donor (ECD) kidneys in order to (1) describe their influence on perfusion parameters and (2) determine their influence on early graft outcome. METHODS Two hundred seventy-five consecutive ECD kidneys were preserved in our laboratory between 1/1/94 and 12/31/97 by either machine perfusion (MP) or cold storage (CS). ECD kidneys were defined as those requiring pretransplant biopsy. ECD kidneys were divided by method of preservation and MP kidneys were randomized to receive prostaglandin E1 (MP+PGE1), trifluoperazine (TFP), verapamil (VER), papaverine (PAP), mannitol (MAN), or no intervention during the period of machine perfusion. CS kidneys were randomized to receive PGE1 (CS+PGE1), TFP, VER, PAP, or no intervention. All MP kidneys were preserved by continuous hypothermic pulsatile perfusion using Belzer II solution and perfusion parameters were measured every hour during pulsatile perfusion. All CS kidneys were stored in 1.0 L of University of Wisconsin (UW) solution. RESULTS The addition of PGE1 to machine perfusate increased renal flow and decreased renal resistance. Moreover, the MP+PGE1-treated group was associated with improved early graft function compared to all other groups. The addition of VER, TFP, PAP, or MAN influenced neither the perfusion characteristics nor the incidence of early graft function in MP kidneys. Similarly, the addition of VER, TFP, or PAP did not influence early graft function in the CS kidneys. The CS+PGE1 group exhibited a significantly lower incidence of early graft function than did the MP+PGE1 group. CONCLUSIONS PGE1 treatment during machine preservation improves hydrostatic perfusion parameters and reduces the incidence of delayed graft function in ECD kidneys. Moreover, the addition of PGE1, TFP, VER, or PAP to UW does not influence early graft function in the CS kidney.
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Kapur S. Phosphorus balance and prostate cancer. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 1999; 37:623-6. [PMID: 10522150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Prostatic diseases affect men over the age of 45 and increase in frequency with age so that by the eighth decade more than 90% of men have Benign Prostatic Hyperplasia, (BPH), of which some progress to Carcinoma of Prostate (CaP). CaP, the most common malignancy in men, is also the second most common cause of death in men. Over the last three decades the mortality rate for CaP has steadily increased. There, however, are scant clues to the aetiology/pathogenesis of CaP. As treatment failures of advanced carcinoma continue to frustrate clinicians, emphasis has recently been focused on possible preventive strategies. Several studies support the view that higher levels of 1,25-(OH)2D, the active metabolite of vitamin D, reduce the risk of BPH and CaP. Men with high serum levels of 1,25-(OH)2D have a reduced risk of poorly differentiated and clinically advanced CaP. Hypercalcemic activity of 1,25-(OH)2D or its analogues, however, thwart their use for therapy in humans. Incidentally, a low dietary intake of phosphorus has been reported to increase serum levels of 1,25-(OH)2D. In addition, dietary fructose reduces plasma phosphate levels by 30 to 50% for more than 3 hr. Fruit intake has, indeed, been shown to be associated with reduced risk of CaP, particularly the advanced type. These observations, taken together, support that dietary determinants of hypophosphatemia, leading to increased plasma levels of 1,25-(OH)2D, could reduce the risk of ageing men to develop prostatic diseases, both BPH and/or carcinoma of Prostate.
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Meyer JH, Kapur S, Houle S, DaSilva J, Owczarek B, Brown GM, Wilson AA, Kennedy SH. Prefrontal cortex 5-HT2 receptors in depression: an [18F]setoperone PET imaging study. Am J Psychiatry 1999; 156:1029-34. [PMID: 10401447 DOI: 10.1176/ajp.156.7.1029] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Widespread disturbances of serotonin (5-HT) are implicated in the pathophysiology of depression. Of 5-HT receptor abnormalities reported, the most replicated finding is increased 5-HT2 receptor binding in the postmortem prefrontal cortex of depressed suicide victims. The extent to which these findings exist in depressed persons without recent suicide attempts is uncertain. The objective of this study was to evaluate 5-HT2 receptors in depressed patients who were medication-free and who had not made recent suicide attempts. METHOD With the use of [18F]setoperone and positron emission tomography (PET), 5-HT2 receptor binding potential was assessed in 14 depressed and 19 healthy subjects. Exclusion criteria for depressed patients included use of antidepressant medication within the past 6 months, a history of suicide attempts within the past 5 years, other current axis I disorders including bipolar disorder, and the presence of psychotic symptoms. The 5-HT2 (setoperone) binding potential in the two groups of subjects was compared by analysis of covariance with age as the covariate. RESULTS Age had a significant effect on 5-HT2 binding potential, but depression did not. The interaction of age and depression was not significant. CONCLUSIONS The 5-HT2 binding potential is not increased in untreated depressed subjects who have not made recent suicide attempts. This negative finding does not rule out the possibility that there is a role for 5-HT2 receptors in treatment or that 5-HT2 receptors are increased in highly suicidal states.
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Meyer JH, Cho R, Kennedy S, Kapur S. The effects of single dose nefazodone and paroxetine upon 5-HT2A binding potential in humans using [18F]-setoperone PET. Psychopharmacology (Berl) 1999; 144:279-81. [PMID: 10435395 DOI: 10.1007/s002130051004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
RATIONALE Alterations in 5-HT2A receptor binding are implicated in suicidality and depression. 5-HT2A receptors may also be involved in the therapeutic effects of antidepressants. OBJECTIVES The purpose of this study was to assess the effect of paroxetine and nefazodone on 5-HT2A receptors after a single dose. METHODS Seven subjects received a single dose of nefazodone 200 mg and five subjects received a single dose of paroxetine 20 mg. Before and after the dose, 5-HT2A binding potentials (Bmax/Kd) were determined in each subject using [18F]-setoperone PET. RESULTS Nefazodone induced a significant change in 5-HT2A binding potential (-39+/-17%,, P = 0.003) while paroxetine showed no significant alteration of 5-HT2A binding potential (+3+/-13%, P = 0.73). CONCLUSIONS The change in 5-HT2A binding potential seen with nefazodone represents blockade of 5-HT2A receptors by the drug. We do not find evidence for acute downregulation of 5-HT2A receptors with paroxetine within 9 h.
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Remington G, Kapur S. D2 and 5-HT2 receptor effects of antipsychotics: bridging basic and clinical findings using PET. J Clin Psychiatry 1999; 60 Suppl 10:15-9. [PMID: 10340683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The advent of a number of new antipsychotics has been paralleled by efforts to better delineate their mechanisms of action and, in doing so, further our understanding of schizophrenia and its pathophysiology. Technological advances, such as positron emission tomography (PET), have proven to be powerful tools in this process, allowing us to evaluate in vivo models based primarily on in vitro evidence. Combined serotonin-2/dopamine-2 (5-HT2/D2) antagonism represents one such model, and we now have PET evidence available that can be extrapolated to our understanding and clinical use of both conventional and novel antipsychotics.
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Kapur S, Cho R, Jones C, McKay G, Zipursky RB. Is amoxapine an atypical antipsychotic? Positron-emission tomography investigation of its dopamine2 and serotonin2 occupancy. Biol Psychiatry 1999; 45:1217-20. [PMID: 10331115 DOI: 10.1016/s0006-3223(98)00204-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND All currently available atypical antipsychotics have, at clinically relevant doses: i) high serotonin (5-HT)2 occupancy; ii) greater 5-HT2 than dopamine (D)2 occupancy; and iii) a higher incidence of extrapyramidal side effects when their D2 occupancy exceeds 80%. A review of pharmacologic and behavioral data suggested that amoxapine should also conform to this profile; therefore, we undertook a positron-emission tomography (PET) study of its 5-HT2 and D2 occupancy. METHODS Seven healthy volunteers received 50-250 mg/day of amoxapine for 5 days and then had [11C]-raclopride and [18F]-setoperone PET scans. RESULTS 5-HT2 receptors showed near saturation at doses of 100 mg/day and above. The D2 receptor occupancies showed a dose-dependent increase, never exceeding 80%; at all doses 5-HT2 occupancy exceeded D2 occupancy. CONCLUSIONS PET data show that amoxapine's profile is very similar to that of the established atypical antipsychotics. These data, together with amoxapine's in vitro pharmacologic profile, effectiveness in animal models, and efficacy in psychotic depression raise the possibility of amoxapine as an "atypical" antipsychotic agent in the treatment of schizophrenia.
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Kapur S, Marcotte B, Marette A. Mechanism of adipose tissue iNOS induction in endotoxemia. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:E635-41. [PMID: 10198298 DOI: 10.1152/ajpendo.1999.276.4.e635] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the present study was to investigate the mechanism of adipose tissue inducible nitric oxide synthase (iNOS) induction in endotoxemia. Systemic administration of the bacterial endotoxin lipopolysaccharide (LPS) to rats for </=8 h markedly increased iNOS mRNA and protein levels in white and brown adipose tissues. This effect was comparable to or greater than the induction of iNOS in liver, kidney, or skeletal muscle. iNOS activity was also found to be greatly enhanced in both white and brown adipose tissues of LPS-treated rats (an approximately 12- to 20-fold increase). Treatment of cultured 3T3-L1 adipocytes with LPS, tumor necrosis factor-alpha (TNF-alpha), or interferon-gamma (IFN-gamma) alone failed to induce iNOS activity. However, when used in combination, TNF-alpha, IFN-gamma, and LPS markedly and synergistically increased iNOS activity in these cells. In conclusion, these results suggest that adipose tissue is a major site of iNOS expression in endotoxemia. Our data further indicate that iNOS induction can be reproduced in vitro in cultured adipocytes and that a concerted action of cytokines and endotoxin is needed for maximal activation of the enzyme.
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Cho R, Kapur S, Du L, Hrdina P. Relationship between central and peripheral serotonin 5-HT2A receptors: a positron emission tomography study in healthy individuals. Neurosci Lett 1999; 261:139-42. [PMID: 10081968 DOI: 10.1016/s0304-3940(98)00998-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
5-HT2A receptors on platelet membranes are often measured as indirect markers of the central 5-HT2A receptors. However, the 5-HT2A receptors on the platelets and those in the brain have never been assessed simultaneously in humans. The purpose of this study was to evaluate the relationship between platelet membrane and neocortical 5-HT2A receptors measured simultaneously in normal healthy volunteers. Twelve healthy volunteers had the 5-HT2A receptors on their platelet membranes assessed in vitro using [3H]lysergic acid diethylamide ([3H]LSD) and their central 5-HT2A receptors measured in vivo using [18F]setoperone and positron emission tomography (PET) imaging. We find no significant correlation between the binding potential (Bmax/Kd) of 5-HT2A receptors on platelets and in brain in the same individual (F1,10 = 0.7, P = 0.42). The study was limited by a small sample and the fact the two different ligands were used (i.e. LSD for platelets and setoperone for brain); nonetheless, the findings suggest that changes in platelet 5-HT2A receptors may not indicate similar changes in central 5-HT2A receptors.
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Bonham CA, Kapur S, Dodson SF, Dvorchik I, Corry RJ. Potential use of marginal donors for pancreas transplantation. Transplant Proc 1999; 31:612-3. [PMID: 10083259 DOI: 10.1016/s0041-1345(98)01579-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Kapur S, Zipursky RB, Remington G. Clinical and theoretical implications of 5-HT2 and D2 receptor occupancy of clozapine, risperidone, and olanzapine in schizophrenia. Am J Psychiatry 1999; 156:286-93. [PMID: 9989565 DOI: 10.1176/ajp.156.2.286] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Dopamine D2 receptor occupancy measurements provide a valid predictor of antipsychotic response, extrapyramidal side effects, and elevation of prolactin levels. The new antipsychotics clozapine, risperidone, and olanzapine obtain antipsychotic response with few extrapyramidal side effects and little prolactin elevation. The purpose of this study was to compare the D2 and serotonin 5-HT2 receptor occupancies of these drugs in patients receiving multiple-dose, steady-state regimens. METHOD Forty-four patients with schizophrenia (16 taking risperidone, 2-12 mg/day; 17 taking olanzapine, 5-60 mg/day; and 11 taking clozapine, 75-900 mg/day) had their D2 and 5-HT2 occupancies determined with the use of [11C]raclopride and [18F]setoperone, respectively, and positron emission tomography imaging. RESULTS Clozapine showed a much lower D2 occupancy (16%-68%) than risperidone (63%-89%) and olanzapine (43%-89%). Risperidone and olanzapine gave equal D2 occupancies at doses of 5 and 20 mg/day, respectively. All three drugs showed greater 5-HT2 than D2 occupancy at all doses, although the difference was greatest for clozapine. CONCLUSIONS Clozapine, at doses known to be effective in routine clinical settings, showed a D2 occupancy clearly lower than that of typical antipsychotics, while risperidone and olanzapine at their usual clinical doses gave the same level of D2 occupancy as low-dose typical antipsychotics. The results also suggest that some previous clinical comparisons of antipsychotics may have been confounded by different levels of D2 occupancy. Clinical comparisons of these drugs, matching for D2 occupancy, may provide a better measure of their true "atypicality" and will help in understanding the contribution of non-D2 receptors to antipsychotic effects.
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Simons FE, Roberts JR, Gu X, Kapur S, Simons KJ. The clinical pharmacology of brompheniramine in children. J Allergy Clin Immunol 1999; 103:223-6. [PMID: 9949311 DOI: 10.1016/s0091-6749(99)70494-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Brompheniramine has been widely used in the treatment of allergic rhinitis and other disorders during the past 4 decades. There are no published studies of its clinical pharmacology in children. OBJECTIVES This study was performed to test the hypothesis that brompheniramine would have a prompt onset of action and a 24-hour duration of action in children. METHODS Before brompheniramine 4 mg was ingested, and at intervals from 0.5 to 30 hours thereafter, blood samples were obtained for quantitation of plasma brompheniramine concentrations by means of HPLC. Concurrently, epicutaneous tests with histamine phosphate were performed; wheals and flares were traced at 10 minutes, and the areas were measured by using a computerized digitizing system. RESULTS In 14 children, mean age 9.5 +/- 0.4 years (SEM), the peak brompheniramine concentration was 7.7 +/- 0.7 ng/mL, and the time at which peak concentrations occurred was 3.2 +/- 0.3 hours. The terminal elimination half-life was 12.4 +/- 1.1 hours, and the oral clearance was 20.2 +/- 2.1 mL/min/kg. Compared with predose areas, the wheals and flares produced by histamine phosphate 1 mg/mL were significantly decreased from 0.5 to 30 hours and from 1 to 30 hours, respectively (P <.05), with mean maximum inhibition at 12 (52% +/- 9%) and 6 hours (72% +/- 10%), respectively. CONCLUSIONS In children a single dose of brompheniramine produces prompt, long-lasting peripheral H1 -blockade. Revised dosage regimens may be needed in this population.
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Bonham CA, Kapur S, Geller D, Fung JJ, Pinna A. Excision and immediate revascularization for hepatic artery pseudoaneurysm following liver transplantation. Transplant Proc 1999; 31:443. [PMID: 10083180 DOI: 10.1016/s0041-1345(98)01698-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Kapur S, Bonham CA, Dodson SF, Dvorchik I, Corry RJ. Strategies to expand the donor pool for pancreas transplantation. Transplantation 1999; 67:284-90. [PMID: 10075595 DOI: 10.1097/00007890-199901270-00017] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Our organ procurement organization has been forced to liberalize the donor criteria in order to expand the donor pool for pancreas transplantation. In this report, we describe our experience using whole organ pancreatic grafts from "marginal" donors, which include grafts obtained from donors over 45 years of age and from donors who were identified to be hemodynamically unstable at the time of organ retrieval. METHODS A prospective study was performed between July 1994 and March 1998, during which time 137 pancreas transplants were performed at our center using organs procured by our own surgeons (organs sent by other teams were excluded). The rapid en bloc technique was used exclusively. The use of pancreatic grafts from marginal donors was analyzed for short-term and overall graft survival, and for delayed graft function and complications. RESULTS Overall pancreas graft survival for our series was 83%, with a mean follow-up of 23 months. There were 22 pancreas grafts from donors over 45 years of age, 13 of whom were greater than 50 years of age. The actual graft survival rate of the over-45 donor group was 86%. Fifty-one grafts were removed from hemodynamically unstable donors on high-dose vasopressors. The actual graft survival in this group was 86%. There was no significant difference found in graft survival between recipients of pancreatic grafts from marginal and nonmarginal donors. Delayed graft function was exhibited by more recipients of grafts from donors on high-dose vasopressors (P<0.05), but this had no effect on long-term graft survival and endocrine function. Recipients of marginal donor grafts did not have higher rates of complication compared to recipients of nonmarginal grafts. CONCLUSIONS Based on our results, we currently employ a graft selection strategy not limited by donor age or hemodynamic stability. Our selection of pancreas organs for transplantation is based on careful inspection of the pancreas and determination of the adequacy of the ex vivo flush. Our results suggest that the current pancreas donor pool may be expanded substantially.
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Lewis R, Kapur S, Jones C, DaSilva J, Brown GM, Wilson AA, Houle S, Zipursky RB. Serotonin 5-HT2 receptors in schizophrenia: a PET study using [18F]setoperone in neuroleptic-naive patients and normal subjects. Am J Psychiatry 1999; 156:72-8. [PMID: 9892300 DOI: 10.1176/ajp.156.1.72] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Several postmortem studies have reported a decreased density of serotonin 5-HT2 receptors in the prefrontal cortex in schizophrenia. The purpose of this study was to investigate this in patients with schizophrenia by means of [18F]setoperone and positron emission tomography (PET) imaging. METHOD Thirteen neuroleptic-free patients with schizophrenia, 10 of whom were also neuroleptic-naive, were compared with a group of 26 normal subjects in the same age range. The density of 5-HT2 receptors was assessed with the use of [18F]setoperone and PET in standardized cortical regions of interest. RESULTS Increasing age was associated with similar declines in 5-HT2 receptors in all cortical regions in the patient group and in the normal comparison group. After control for the effect of age, there was no statistically significant difference between the patients and the comparison subjects in 5-HT2 receptor density in any of the cortical regions. CONCLUSIONS This study failed to find the decrease in 5-HT2 receptors reported in postmortem studies of schizophrenia. The study had the power to detect a decrease of 25% or more in 5-HT2 receptors, which was anticipated on the basis of the previous postmortem studies. Thus, a primary serotonergic abnormality in schizophrenia, if one exists, is either small or unlikely to be at the level of the 5-HT2 receptors. This finding does not rule out a therapeutic role for 5-HT2 antagonists in schizophrenia, but it does suggest that the therapeutic contribution is likely to be an indirect one.
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MacKinnon CD, Kapur S, Hussey D, Verrier MC, Houle S, Tatton WG. Contributions of the mesial frontal cortex to the premovement potentials associated with intermittent hand movements in humans. Hum Brain Mapp 1998; 4:1-22. [DOI: 10.1002/(sici)1097-0193(1996)4:1<1::aid-hbm1>3.0.co;2-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Casavilla FA, Rakela J, Kapur S, Irish W, McMichael J, Demetris AJ, Starzl TE, Fung JJ. Clinical outcome of patients infected with hepatitis C virus infection on survival after primary liver transplantation under tacrolimus. LIVER TRANSPLANTATION AND SURGERY : OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION FOR THE STUDY OF LIVER DISEASES AND THE INTERNATIONAL LIVER TRANSPLANTATION SOCIETY 1998; 4:448-54. [PMID: 9791154 PMCID: PMC2954759 DOI: 10.1002/lt.500040605] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The outcome of hepatitis C virus (HCV) infection on patient and graft survival after orthotopic liver transplantation (OLT) has been controversial. An earlier experience with a higher dose of tacrolimus (>/=0.1 mg/kg/d intravenously and >/=0.2 mg/kg/d orally) was associated with a worse clinical outcome in patients infected with HCV. The clinical outcome of 183 liver transplant recipients with end-stage liver disease (ESLD) secondary to HCV infection (HCV group) was compared with a contemporary cohort of 556 patients with HCV infection who underwent transplantation for nonviral, nonmalignant ESLD (control group). All patients were prospectively screened for anti-HCV antibodies and HCV RNA by reverse-transcriptase polymerase chain reaction. All OLT patients were receiving low-dose tacrolimus immunosuppression. Cumulative patient survival rates for the HCV group were 80% after 1 year and 75% after 3 years compared with rates of 84% and 78%, respectively, in the control group (P = .452). Primary graft survival rates at the same time intervals for the HCV group and the control group were 72% and 77.5% at 1 year and 67% and 72% at 3 years, respectively (P = .144). The incidence of re-transplantation (re-OLT) in the HCV group and the control group was 12.6% and 10.4%, respectively (P = .42). Chronic HCV infection as an indication for OLT with a lower dose of tacrolimus immunosuppression (</=0.05 mg/kg/d intravenously and </=0.1 mg/kg/d orally) is associated with a similar patient and graft survival as those without HCV infection.
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Kapur S, Gupta SP. Dr Yellapragada SubbaRow (1895-1948): the man and the method. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 1998; 36:1087-92. [PMID: 10085777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Remington G, Kapur S, Zipursky RB. Pharmacotherapy of first-episode schizophrenia. Br J Psychiatry Suppl 1998; 172:66-70. [PMID: 9764129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND A growing interest in first-episode schizophrenia reflects the belief that this line of investigation will lead to further developments regarding schizophrenia's aetiology, course and outcome. METHOD Evidence from more recent clinical trials involving first-episode schizophrenia is integrated with neuroimaging data, specifically positron emission tomography, to provide direction regarding pharmacotherapy. RESULTS Individuals with a first episode of schizophrenia appear particularly responsive to pharmacotherapy, as well as quite sensitive to side-effects. At the same time, current clinical and receptor-binding data support the efficacy of low-dose neuroleptic treatment. CONCLUSIONS Early and effective treatment of schizophrenia has been associated with better long-term outcome. Low-dose neuroleptic therapy is an effective treatment strategy and the diminished risk of side-effects with this approach may further enhance compliance and outcome.
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Remington G, Kapur S, Zipursky R. APA Practice Guideline for schizophrenia: risperidone equivalents. American Psychiatric Association. Am J Psychiatry 1998; 155:1301-2. [PMID: 9734565 DOI: 10.1176/ajp.155.9.1301a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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185
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Kapur S, Mittal A. Incidence of HIV infection & its predictors in blood donors in Delhi. Indian J Med Res 1998; 108:45-50. [PMID: 9785678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
The concurrence of human immunodeficiency virus (HIV) infection with hepatitis B virus (HBV) and syphilis and the trend that these infections have followed in blood donors during the last eight years from 1989 to 1997 were studied at a Zonal Blood Testing Centre in New Delhi. Overall, HIV was positive in 0.068 per cent blood donors in this period. A significant rise was found in HIV infection (particularly in a small subgroup of voluntary donors) after 1995 and in VDRL reactivity after 1993. However, no significant increase was found in hepatitis B surface antigen (HBsAg) positivity. HIV seroprevalence in replacement donors, which represents the low risk general population, increased gradually from 0 in 1991 to an average of 0.060 per cent in 1997. HbsAg and VDRL reactivity was present in 12.2 and 11.8 per cent of HIV positive cases while it was present in 1.2 and 2.3 per cent of HIV negative cases respectively. HBsAg was found 10.4 times and VDRL reactivity 5.9 times more often in HIV positive donors as compared to HIV negative donors. Thus, HIV infection is likely to be more prevalent in communities with a high HBsAg positivity and VDRL reactivity.
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Kapur S, Zipursky RB. Do loxapine plus cyproheptadine make an atypical antipsychotic? PET analysis of their dopamine D2 and serotonin2 receptor occupancy. ARCHIVES OF GENERAL PSYCHIATRY 1998; 55:666-8. [PMID: 9672060 DOI: 10.1001/archpsyc.55.7.666] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Kapur S, Zipursky RB, Remington G, Jones C, DaSilva J, Wilson AA, Houle S. 5-HT2 and D2 receptor occupancy of olanzapine in schizophrenia: a PET investigation. Am J Psychiatry 1998; 155:921-8. [PMID: 9659858 DOI: 10.1176/ajp.155.7.921] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE Olanzapine is a new atypical antipsychotic recently introduced for the treatment of schizophrenia. The purpose of this study was to investigate olanzapine's binding to the serotonin 5-HT2 and dopamine D2 receptors in schizophrenic patients being treated with clinically relevant doses. METHOD Twelve patients with schizophrenia were randomly assigned to 5, 10, 15, or 20 mg/day of olanzapine in a prospective fashion. Three other subjects taking 30-40 mg/day were also included. Once steady-state plasma levels were achieved, dopamine D2 and serotonin 5-HT2 receptors were assessed by using [11C]raclopride and [18F]setoperone positron emission tomography imaging, respectively. Ratings of clinical status, extrapyramidal side effects, and prolactin levels were also obtained. RESULTS Olanzapine induced near saturation of the 5-HT2 receptors, even at 5 mg/day. Its D2 occupancy increased with dose: patients taking 5-20 mg/day showed 43%-80% D2 occupancy, while patients taking 30-40 mg/day showed 83%-88%. CONCLUSIONS Olanzapine is a potent 5-HT2 blocker and shows a higher 5-HT2 than D2 occupancy at all doses. However, its D2 occupancy is higher than that of clozapine and similar to that of risperidone. In the usual clinical dose range of 10-20 mg/day, its occupancy varies from 71% to 80%, and this restricted range may explain its freedom from extrapyramidal side effects and prolactin elevation. However, doses of 30 mg/day and higher are associated with more than 80% D2 occupancy and may have a higher likelihood of prolactin elevation and extrapyramidal side effects.
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Jennings JM, McIntosh AR, Kapur S, Zipursky RB, Houle S. Functional network differences in schizophrenia: a rCBF study of semantic processing. Neuroreport 1998; 9:1697-700. [PMID: 9665585 DOI: 10.1097/00001756-199806010-00005] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Studies of regional cerebral blood flow in patients with schizophrenia have led to the idea that dysfunctional neurocircuitry may play a role in patients' cognitive deficits. The present PET study was designed to explore this idea by comparing the functional neural networks associated with semantic processing for patients and normal controls through structural equation modeling (path analysis). The patients showed significantly different neural interactions among frontal regions, between the frontal and temporal cortices, and between the frontal lobe and anterior cingulate than controls. These discrepancies were especially striking given there were minimal group differences in task performance. Results suggest that schizophrenia involves a neural abnormality that is evident in functional networks during cognitive performance.
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Zipursky RB, Lambe EK, Kapur S, Mikulis DJ. Cerebral gray matter volume deficits in first episode psychosis. ARCHIVES OF GENERAL PSYCHIATRY 1998; 55:540-6. [PMID: 9633673 DOI: 10.1001/archpsyc.55.6.540] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Structural brain differences including decreased gray matter and increased cerebrospinal fluid volumes have been observed in the brains of chronically ill patients with schizophrenia. We hypothesized that deficits in gray matter volume would be present in patients presenting with a first episode of nonaffective psychosis. METHODS We used magnetic resonance imaging to compare the brains of 77 patients assessed as having a first episode of psychosis (meeting DSM-III-R criteria for schizophrenia, schizophreniform disorder, schizoaffective disorder, delusional disorder, or psychotic disorder not otherwise specified) with those of 61 healthy controls matched for age, sex, race, and parental socioeconomic status. Axial, dual-echo scans of the whole brain were segmented into gray matter, white matter, and cerebrospinal fluid compartments using a computerized volumetric approach. These measures were corrected for the significant effects of intracranial volume and age prior to performing between-group comparisons. RESULTS The first episode psychosis group had significantly smaller gray matter volume (t[136] = -2.2; P = .03) and greater cerebrospinal fluid volume (t[136] = 2.5; P = .02) than normal controls. In the patient group, gray matter volumes were positively correlated with estimates of IQ but not with age of onset, duration of illness, or measures of premorbid functioning. CONCLUSIONS Deficits in gray matter volume are present in patients experiencing first episode nonaffective psychosis. The magnitude of these differences is smaller than has been described in more chronically ill patients.
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Houle S, Kapur S, Gunn R. Binding Potential of [18F]Setoperone: Reproducibility of Measures by the Simplified Reference Tissue Method. Neuroimage 1998. [DOI: 10.1016/s1053-8119(18)31890-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
One of the important questions cognitive theories of reasoning must address is whether logical reasoning is inherently sentential or spatial. A sentential model would exploit nonspatial (linguistic) properties of representations whereas a spatial model would exploit spatial properties of representations. In general terms, the linguistic hypothesis predicts that the language processing regions underwrite human reasoning processes, and the spatial hypothesis suggests that the neural structures for perception and motor control contribute the basic representational building blocks used for high-level logical and linguistic reasoning. We carried out a [(15)O] H(2)O PET imaging study to address this issue. Twelve normal volunteers performed three types of deductive reasoning tasks (categorical syllogisms, three-term spatial relational items, and three-term nonspatial relational items) while their regional cerebral blood flow pattern was recorded using [(15)O] H(2)O PET imaging. In the control condition subjects semantically comprehended sets of three sentences. In the deductive reasoning conditions subjects determined whether the third sentence was entailed by the first two sentences. The areas of activation in each reasoning condition were confined to the left hemisphere and were similar to each other and to activation reported in previous studies. They included the left inferior frontal gyrus (Brodmann area 45, 47), a portion of the left middle frontal gyrus (Brodmann area 46), the left middle temporal gyrus (Brodmann areas 21, 22), a region of the left lateral inferior temporal gyrus and superior temporal gyrus (Brodmann areas 22, 37), and a portion of the left cingulate gyrus (Brodmann areas 32, 24). There was no significant right-hemisphere or parietal activation. These results are consistent with previous neuroimaging studies and raise questions about the level of involvement of classic spatial regions in reasoning about linguistically presented spatial relations.
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Abstract
Positron emission tomography was used to identify brain regions that showed general increase or decrease in regional cerebral blood flow (rCBF) across time that was task-independent. Twelve male subjects were scanned eight times: the first and last scans were taken while subjects performed a baseline fixation task and the middle six scans were taken while subjects performed a visuomotor activation task. To determine whether there was a consistency across different studies in the regions that showed this time-related change in rCBF two additional datasets were analyzed. There were similarities across all three studies in the regions that showed a monotonic task-independent change in activity. In all three studies there was a general bilateral decrease in rCBF of occipital and temporal areas across scans that might be related to habituation in the visual domain. Increases in rCBF were found in anterior cingulate, postcentral gyrus, and precentral gyrus across studies. It is likely that these changes reflect motor learning and motor program retrieval. This implies that, unless the experimenter controls for time-dependent changes in brain activity, the interpretation of task-related changes in rCBF may be confounded by these monotonic changes in rCBF. We present analytic strategies to identify experimental effects that are independent of nonspecific time effects, which can be used when it is not possible to control these effects through counterbalancing the experimental design. Nonspecific confounds are particularly relevant in functional MRI studies in which the number of scans acquired per study is much larger.
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Iidaka T, Anderson N, Kapur S, Okamoto C, Cabeza R, Craik F. Differential Effects of Divided Attention on Encoding and Retrieval in Episodic Memory Revealed by Positron Emission Tomography. Neuroimage 1998. [DOI: 10.1016/s1053-8119(18)30923-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Jennings JM, McIntosh AR, Kapur S. Mapping neural interactivity onto regional activity: an analysis of semantic processing and response mode interactions. Neuroimage 1998; 7:244-54. [PMID: 9597665 DOI: 10.1006/nimg.1998.0325] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuroimaging studies of cognition have typically been designed to identify brain regions that are active during a cognitive process. However, identifying how brain regions interact may be equally important. In a recent study we found that the pattern of activation associated with a semantic task differed depending on how subjects made a response, suggesting that there was an interaction between the neural systems underlying response mode and semantic processing (J. M. Jennings et al., 1997, NeuroImage 5, 229-239). This result raises two important questions, which we examined here: (1) How did the regions underlying semantic performance influence one another, or interact, to produce a different pattern of activation in each case? (2) What can be learned about the neurobiology of semantic processing when different regions are identified as a function of response? We addressed these questions using structural equation modeling. This technique produced functional network models representing the effect of different regions on each other during the semantic task for each response. A common network of regions associated with semantic processing was observed and included the left inferior frontal and left superior temporal cortices, with other regions brought into that network depending on response (e.g., right middle frontal). Moreover, changes in the influences among these regions across response condition predicted the pattern of activation found previously. These results show how an arbitrary response can affect the neural pathways associated with a cognitive process, likely due to the parallel and reentrant organization of the brain, and emphasize the importance of examining functional connections when studying cognition.
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Abstract
With a decade of neuroreceptor imaging of antipsychotics behind us, this article attempts to synthesise what has been learnt about the mechanism of action of antipsychotics using these techniques. The data show that: (i) the 'typical' antipsychotics bind mainly to the dopamine D2 receptor, and that 60-80% D2 occupancy may provide optimal antipsychotic response with little extrapyramidal side effects; (ii) all the clinically available 'atypical' antipsychotics show a higher occupancy of the 5-HT2 than D2 receptors; (iii) however, these 'atypical' antipsychotics differ in their D2 occupancy. The D2 occupancy of risperidone is within the typical range (i.e. > 60%) while that of clozapine is clearly lower (< 60%); (iv) antipsychotics with combined 5-HT2/D2 antagonism lose some of their 'atypical' properties if used in doses where their D2 occupancy is too high (> 80%). Based on these data a framework is suggested wherein antipsychotics may be classified on the basis of their D2 and 5-HT2 occupancy in patients at steady state while taking clinically relevant doses. Within this framework typical antipsychotics are classified as 'high-D2', resperidone as 'high-D2 high-5HT2' and clozapine as a 'low-D2 high-5HT2' antipsychotic. The justification, limitations and the value of this framework in understanding and investigating newer antipsychotics is discussed.
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Remington G, Kapur S, Zipursky R. The relationship between risperidone plasma levels and dopamine D2 occupancy: a positron emission tomographic study. J Clin Psychopharmacol 1998; 18:82-3. [PMID: 9472848 DOI: 10.1097/00004714-199802000-00014] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Kapur S, Zipursky R, Remington G, Jones C, McKay G, Houle S. PET evidence that loxapine is an equipotent blocker of 5-HT2 and D2 receptors: implications for the therapeutics of schizophrenia. Am J Psychiatry 1997; 154:1525-9. [PMID: 9356559 DOI: 10.1176/ajp.154.11.1525] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Loxapine, a dibenzoxazepine antipsychotic, is closely related to clozapine and shares clozapine's high affinity for binding to serotonin 5-HT2 and dopamine D4 receptors. The purpose of this study was to document loxapine's 5-HT2 and D2 receptor occupancy in vivo in patients with psychoses. METHOD Ten patients who were taking loxapine (10-100 mg/day) had their D2 and 5-HT2 receptors assessed by means of positron emission tomography with [11C]raclopride and [18F]setoperone, respectively. RESULTS The D2 receptor occupancy ranged from 43% to 90%; 5-HT2 occupancy varied from 27% to near saturation. Statistical comparison of the results showed that loxapine was equipotent in blocking 5-HT2 and D2 receptors. CONCLUSIONS Loxapine differs from typical neuroleptics in demonstrating a high degree of 5-HT2 receptor occupancy. However, it is not "atypical" like clozapine and risperidone, since its 5-HT2 occupancy is not higher than its D2 occupancy. The results demonstrate that a high level of 5-HT2 occupancy is not a sufficient condition for atypicality. If atypical antipsychotic action is predicated on a combination of 5-HT2 and D2 effects, then it requires > 80% 5-HT2 occupancy in conjunction with < 80% D2 occupancy.
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Kapur S, Bédard S, Marcotte B, Côté CH, Marette A. Expression of nitric oxide synthase in skeletal muscle: a novel role for nitric oxide as a modulator of insulin action. Diabetes 1997; 46:1691-700. [PMID: 9356014 DOI: 10.2337/diab.46.11.1691] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Previous studies have shown that nitric oxide synthase (NOS), the enzyme that catalyzes the formation of nitric oxide (NO), is expressed in skeletal muscle. The aim of the present study was to test the hypothesis that NO can modulate glucose metabolism in slow- and fast-twitch skeletal muscles. Calcium-dependent NOS was detected in skeletal muscle, and the enzyme activity was greater in fast-type extensor digitorum longus (EDL) muscles than in slow-type soleus muscles. Both the neuronal-type (nNOS) and endothelial-type (eNOS) enzymes are expressed in resting skeletal muscles. However, nNOS protein was only detected in EDL muscles, whereas eNOS protein contents were comparable in soleus and EDL muscles. NOS expression in muscle cryosections (diaphorase histochemistry) was located in vascular endothelium and in muscle fibers, and the staining was greater in type IIb than in type I and IIa fibers. The macrophage-type inducible NOS (iNOS) was not detected in resting muscle, but endotoxin treatment induced its expression, concomitant with elevated NO production. iNOS induction was associated with impaired insulin-stimulated glucose uptake in isolated rat muscles. In vitro, NOS blockade with specific inhibitors did not affect basal or insulin-stimulated glucose transport in EDL or soleus muscles. In contrast, the NO donors GEA 5024 and sodium nitroprusside induced dose-dependent inhibition (up to 50%) of maximal insulin-stimulated glucose transport in both muscles with minor effects on basal uptake values. GEA 5024 also blunted insulin-stimulated glucose transport and amino acid uptake in cultured L6 muscle cells without affecting insulin binding to its receptor. On the other hand, the permeable cGMP analogue dibutyryl cGMP did not affect muscle glucose transport. These results strongly suggest that NO modulates insulin action in both slow- and fast-type skeletal muscles. This novel autocrine action of NO in muscle appears to be mediated by cGMP-independent pathways.
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Zhuang Z, Merino MJ, Vortmeyer AO, Bryant B, Lash AE, Wang C, Deavers MT, Shelton WF, Kapur S, Chandra RS. Identical genetic changes in different histologic components of Wilms' tumors. J Natl Cancer Inst 1997; 89:1148-52. [PMID: 9262253 DOI: 10.1093/jnci/89.15.1148] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND In young children and infants, Wilms' tumor is the most common cancer of the kidney. Wilms' tumor exhibits heterogeneous histopathologic features, consisting of rapidly proliferating blastemal and epithelial cells and a stromal component that has heterologous elements (e.g., cartilage, bone, and striated muscle). It is unclear whether the stromal and heterologous components of sporadic Wilms' tumor are neoplastic or should be considered non-neoplastic. PURPOSE Our purpose was twofold: 1) to selectively analyze the different histologic tissue components of sporadic Wilms' tumors, including blastemal, epithelial, stromal, and heterologous elements, for loss of heterozygosity (LOH) of the WT1 gene and for expression of the WT1 gene and 2) to determine the role of WT1 gene expression in the development of these tissues. METHODS By use of tissue microdissection techniques, various histologic elements (blastema, stroma, epithelium, and striated muscle) of sporadic Wilms' tumor were obtained from specimens taken from 18 patients. DNA was extracted from the dissected tissue fragments, and DNA solutions were amplified by use of the polymerase chain reaction and the polymorphic genomic markers D11S1392 and D11S904 to detect LOH at the WT1 gene locus (11p13). Three selected specimens with heterologous elements and LOH at 11p13 were analyzed for expression of the WT1 gene by means of the in situ reverse transcription-polymerase chain reaction. RESULTS Nine (50%) of the 18 specimens showed LOH at the WT1 locus. Although identical WT1 gene deletion was consistently observed in all of the various histologic components of these nine specimens, WT1 gene expression was high in the blastemal and epithelial elements and low in the stromal and heterologous elements. CONCLUSIONS AND IMPLICATIONS Identical allelic deletion at 11p13 in all components of the sporadic Wilms' tumors examined suggests that the stromal tissue components are neoplastic rather than non-neoplastic. In conjunction with variable WT1 gene expression in the different histologic components, the results raise the possibility that undifferentiated blastemal cells are the precursors of the stromal and heterologous elements. Morphologically benign stromal and heterologous elements may therefore be derived from neoplastic cells. The developmental state of the various tissue components of Wilms' tumor may be attributed to an altered residual WT1 gene that is required for the maturation of blastemal and epithelial cells but that is not required for the maturation of stromal and heterologous elements.
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Kapur S, Zipursky RB, Jones C, Wilson AA, DaSilva JD, Houle S. Cyproheptadine: a potent in vivo serotonin antagonist. Am J Psychiatry 1997; 154:884. [PMID: 9167527 DOI: 10.1176/ajp.154.6.884a] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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