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B M Cohen

Publications and source records attributed to B M Cohen.

At least 19 recordsLinked to original sources
PubMed2006

Typical and atypical antipsychotic drugs target dopamine and cyclic AMP-regulated phosphoprotein, 32 kDa and neurotensin-containing neurons, but not GABAergic interneurons in the shell of nucleus accumbens of ventral striatum.

Specific neurons in the brain are the primary targets of the action of antipsychotic drugs. Identification and characterization of the nature of these neurons are important for understanding how antipsychotic drugs produce their effects. In previous studies GABAergic/dynorphinergic neurons were identified as a principal cell target of antipsychotic drugs in the shell of nucleus accumbens. In the present study, we further characterized which subpopulations of GABAergic neurons in this area respond after acute administration of antipsychotic drugs. Rats were treated with the typical antipsychotic haloperidol, or the prototype atypical antipsychotic clozapine and killed two hours after treatment. In appropriate sections of brain, double immunofluorescence labeling was performed with antibodies directed against markers specific to candidate cell types and Fos-like proteins (a marker to identify drug-induced cell activation). We reported here that haloperidol- and clozapine-activated neurons showed the following features: 1) approximately 54-57% of them express dopamine and cyclic AMP-regulated phosphoprotein, 32 kDa (a marker for GABAergic medium spiny projection neurons), 2) they appear rarely to be GABAergic interneurons, marked by the calcium binding proteins, parvalbumin, calretinin or calbindin-D28K, 3) about 84-86% of them express the neuropeptide neurotensin (a neurotransmitter most often associated with projection neurons in the site tested). The results suggest that most of the antipsychotic drug-activated neurons in the shell of nucleus accumbens are likely to be neurotensin containing projection neurons.

Animals↗
PubMed2005

Effects of coagulation factor deficiency on plasma coagulation kinetics determined via thrombelastography: critical roles of fibrinogen and factors II, VII, X and XII.

BACKGROUND: Thrombelastography (TEG) is used to assess coagulopathy. However, a comprehensive characterization of the effects of specific coagulation factor deficiencies and mode of activation on TEG data does not exist. METHODS: Thrombelastography was performed for 15 min with control plasma and plasmas deficient (<1% activity) in Factors II, V, VII, VIII, IX, X, XI, XII, or XIII activated with celite (0.28 mg ml(-1)) or tissue factor (TF, 0.1%) (n = 6 per condition). Additional fibrinogen concentration activity (75-345 mg dl(-1)) and Factor II, VII, X and XII activity-response relationships (1%, 6.25%, 12.5%, 25%, 50% and 100% activity) were obtained (n = 8 per condition). Thrombelastography parameters included reaction time (R), angle (alpha), and clot strength (A, amplitude; G, elastic modulus). RESULTS: Celite activation of FXII-deficient plasma, TF activation of FVII-deficient and FX-deficient plasma, and celite or TF activation of FII-deficient plasma resulted in an almost undetectable clot. Compared to control values, celite activation of plasmas deficient in FXI, FIX and FVIII resulted in prolonged R and decreased alpha values, whereas TF activation resulted in decreased alpha values. Celite and TF activation of FV-deficient plasma resulted in prolonged R and decreased alpha values, whereas FXIII-deficient plasma had decreased alpha, A and G-values compared to control values. CONCLUSIONS: The fundamental finding of this study is that coagulation factor deficiencies affect TEG parameters in both a factor-dependent and activation-dependent fashion. Utilizing both celite and TF activation improves the diagnostic power of TEG. Based on such TEG data, more targeted administration of blood products could potentially help improve perioperative hemostatic outcomes.

Blood Coagulation↗
PubMed2003

Dynorphinergic GABA neurons are a target of both typical and atypical antipsychotic drugs in the nucleus accumbens shell, central amygdaloid nucleus and thalamic central medial nucleus.

Administration of typical and atypical antipsychotic drugs leads to activation of cells in the nucleus accumbens shell, central amygdaloid nucleus, and midline thalamic central medial nucleus, implicating important shared effects of these drugs. However, the exact cell types responding to antipsychotic drugs in the nucleus accumbens shell, central amygdaloid nucleus, and midline thalamic central medial nucleus are unclear. We report here that, in a rat model, the results of studies using double immunofluorescence labeling with antibodies directed against markers specific to candidate cell types suggest that the cells responding to haloperidol and clozapine in all three sites are: 1) neurons, rather than astrocytes; 2) inhibitory GABA neurons, but not acetylcholinergic neurons; and 3) dynorphin-containing GABA neurons, but not M-enkephalin-containing GABA neurons. The present study provides pharmacological evidence, at the cellular level in vivo, that the shared effects of antipsychotic drugs, whether typical and atypical, is activation of dynorphinergic GABA neurons in the nucleus accumbens shell, central amygdaloid nucleus, and midline thalamic central medial nucleus. Alternative ways to modulate dynorphinergic GABA neuronal activity or its target receptors might present an important new avenue for the treatment of schizophrenia and other psychotic disorders.

Acetylcholine↗
PubMed2002

Chronic citicoline increases phosphodiesters in the brains of healthy older subjects: an in vivo phosphorus magnetic resonance spectroscopy study.

RATIONALE: Phosphatidylcholine (PtdCho) in brain cell membranes decreases with age. Evidence from both animal and in vitro studies indicates that CDP-choline (citicoline) administration may increase phosphatidylcholine (PtdCho) synthesis and might reverse PtdCho loss. OBJECTIVES: We investigated whether oral citicoline can increase PtdCho synthesis in the brains of older subjects by measuring levels of phosphorus-containing metabolites using proton-decoupled phosphorus magnetic resonance spectroscopy ((31)P-MRS) before and after citicoline treatment. METHODS: All subjects took 500 mg citicoline once orally each day for 6 weeks, then took either citicoline or placebo once orally per day for a second 6-week period. Subjects underwent a (31)P-MRS scan at baseline and following 6 and 12 weeks of treatment. RESULTS: Treatment with citicoline for 6 weeks was associated with a 7.3% increase from baseline levels in brain phosphodiesters ( P=0.008), including an 11.6% increase in glycerophosphoethanolamine ( P=0.002) and a 5.1% increase in glycerophosphocholine ( P=0.137). Subjects who continued to take citicoline for the second 6-week period did not show significant additional increases in the levels of these metabolites. No changes were seen in other phosphorus-containing metabolites. There was a correlation between improvement on the California Verbal Learning Test and increase in phosphodiesters. CONCLUSIONS: The increases in phosphodiesters seen in this study indicate that phospholipid synthesis and turnover were stimulated by 6 weeks of oral citicoline. These results in humans support previous in vitro and animal studies and suggest that the administration of oral citicoline may be of use in reversing age-related changes in the brain.

Administration, Oral↗
PubMed2002

Biexponential transverse relaxation (T(2)) of the proton MRS creatine resonance in human brain.

Differences in proton MRS T(2) values for phosphocreatine (PCr) and creatine (Cr) methyl groups (3.0 ppm) were investigated in studies of phantoms and human brain. Results from phantom studies revealed that T(2) of PCr in solution is significantly shorter than T(2) of Cr. Curve-fitting results indicated that the amplitude-TE curves of the total Cr resonance at 3.0 ppm in human brain (N = 26) fit a biexponential decay model significantly better than a monoexponential decay model (P < 0.006), yielding mean T(2) values of 117 +/- 21 ms and 309 +/- 21 ms. Using a localized, long-TE (272 ms) point-resolved spectroscopy (PRESS) proton MRS during 2 min of photic stimulation (PS), an increase of 12.1% +/- 3.5% in the mean intensity of the total Cr resonance in primary visual cortex (VI) was observed at the end of stimulation (P < 0.021). This increase is consistent with the conversion of 26% of PCr in VI to Cr, which is concordant with (31)P MRS findings reported by other investigators. These results suggest a significantly shorter T(2) for PCr than for Cr in vivo. This difference possibly could be exploited to quantify regional activation in functional spectroscopy studies, and could also lead to inaccuracies in some circumstances when the Cr resonance is used as an internal standard for (1)H MRS studies in vivo.

Adult↗
PubMed2001

Test-retest reliability of DSC MRI CBV mapping in healthy volunteers.

Dynamic susceptibility contrast magnetic resonance imaging (DSC MRI) can be used to generate high resolution maps of cerebral blood volume (CBV). To determine the test-retest reliability, CBV was measured in eight volunteers on two occasions, separated by 4 weeks. The mean ratio (scan 2/scan 1) for 72 cortical regions of interest (ROIs) was 1.03, with a coefficient of variation of 14%. The correlation between the first and second scans was 0.73 (p < 0.0001; 95%). In five hand-drawn ROIs, the mean ratio was 1.08, with a coefficient of variation of 12%. The correlation between scans was 0.84 (p < 0.0001). The data presented here support the hypothesis that DSC MRI CBV mapping has acceptable test-retest reliability.

Adult↗
PubMed2001

Cocaine-induced cerebral vasoconstriction differs as a function of sex and menstrual cycle phase.

BACKGROUND: Chronic cocaine abusing women experience fewer cerebral perfusion defects and less neuronal injury than men with comparable drug use histories. This study assessed whether a basis for this discrepancy is a sex difference in cocaine's acute cerebrovascular effects. METHODS: The subjects in this study were 13 healthy and neurologically normal women, reporting occasional cocaine (mean 13, range 1-40 lifetime cocaine exposures). All subjects were administered cocaine (0.4 mg/kg) intravenously, during both the follicular (days 3-8) and luteal (days 18-24) menstrual cycle phases. Dynamic susceptibility contrast magnetic resonance imaging assessments of relative global cerebral blood volume (CBV) changes were conducted on both study days, 10 min after cocaine administration. RESULTS: Cocaine did not alter CBV in follicular phase women, but reduced luteal phase CBV by 10%, indicative of vasoconstriction (analysis of variance [ANOVA], F = 5.1, p <.05). Postcocaine CBV was lower in men administered the drug via an identical protocol relative to follicular phase women (ANOVA, F = 5.4, p <.04). Postcocaine CBV was also lower in the male referent group relative to luteal phase women, but this difference did not achieve statistical significance. No measurable sex or menstrual cycle phase differences in cocaine's cardiovascular effects were noted. CONCLUSIONS: These findings suggest both menstrual cycle phase and sex differences in cocaine's acute cerebrovascular effects, which may contribute to sex differences in the severity of brain dysfunction found in chronic cocaine abusers. These findings imply that gonadal steroids or the factors they modulate merit study as possible therapeutic agents for reducing cocaine-induced cerebrovascular disorders.

Adult↗
PubMed2001

Influence of baseline hematocrit and hemodilution on BOLD fMRI activation.

Current understanding of blood oxygenation level dependent (BOLD) fMRI physiology predicts a close relationship between BOLD signal and blood hematocrit level. However, neither this relationship nor its effect on BOLD percent activation (BPA) has been empirically examined in man. To that end, BPA in primary visual cortex in response to photic stimulation was determined in a group of 24 normal subjects. A positive linear relationship between BPA and hematocrit was seen, particularly in men. To evaluate the effect of change in hematocrit on BPA, 9 men were studied before and following isotonic saline hemodilution, resulting in an average 6% reduction in hematocrit and an 8-31% reduction in BPA. No significant change in the number of activated pixels was seen. A model of predicted BPA as a function of hematocrit and vessel size was developed, and results from this model closely mirrored the empiric data. These results suggest that hematocrit significantly influences the magnitude of BPA and that such baseline factors should be accounted for when comparing BOLD data across groups of subjects, particularly in the many instances in which hematocrit may vary systematically. Such instances include several disease states as well as studies involving sex differences, drug administration, stress and other factors. Finally, the robust agreement between predicted and empiric data serves to validate a semiquantitative approach to the analysis of BOLD fMRI data.

Brain↗
PubMed2001

Automated identification of Fos expression.

The concentration of Fos, a protein encoded by the immediate-early gene c-fos, provides a measure of synaptic activity that may not parallel the electrical activity of neurons. Such a measure is important for the difficult problem of identifying dynamic properties of neuronal circuitries activated by a variety of stimuli and behaviours. We employ two-stage statistical pattern recognition to identify cellular nuclei that express Fos in two-dimensional sections of rat forebrain after administration of antipsychotic drugs. In stage one, we distinguish dark-stained candidate nuclei from image background by a thresholding algorithm and record size and shape measurements of these objects. In stage two, we compare performance of linear and quadratic discriminants, nearest-neighbour and artificial neural network classifiers that employ functions of these measurements to label candidate objects as either Fos nuclei, two touching Fos nuclei or irrelevant background material. New images of neighbouring brain tissue serve as test sets to assess generalizability of the best derived classification rule, as determined by lowest cross-validation misclassification rate. Three experts, two internal and one external, compare manual and automated results for accuracy assessment. Analyses of a subset of images on two separate occasions provide quantitative measures of inter- and intra-expert consistency. We conclude that our automated procedure yields results that compare favourably with those of the experts and thus has potential to remove much of the tedium, subjectivity and irreproducibility of current Fos identification methods in digital microscopy.

Journal Article↗
PubMed2001

Multinuclear magnetic resonance spectroscopy studies of brain purines in major depression.

OBJECTIVE: Studies of depressed adults have shown abnormalities in cerebral energy metabolism, as noted by low brain levels of nucleoside triphosphate (NTP), which primarily represents adenosine triphosphate (ATP). This study was undertaken to determine whether proton magnetic resonance spectroscopy (1H MRS) measures of the low-field purine resonance, which arises primarily from adenosine phosphates, can be used to assess abnormalities in cerebral purine metabolism in depressed adults. METHOD: Data from 1H MRS and phosphorus-31 (31P) MRS were acquired for depressed and nondepressed comparison subjects. Intensities of the purine resonance, by 1H MRS (7.5-8.5 ppm), and of NTP, by 31P MRS, were determined. RESULTS: Purine resonance intensities did not differ on average between depressed patients and comparison subjects. However, purine levels were approximately 30% lower in female depressed subjects who subsequently responded to fluoxetine treatment than in those who did not respond. Beta-NTP was lower by 21% in responders than in nonresponders and was correlated with purine levels for the depressed subjects. CONCLUSIONS: Brain purine levels are low in female depressed patients who respond to treatment with fluoxetine, suggesting that response to treatment might be predicted by using 1H MRS. These observations also suggest that agents that increase brain adenosine levels may have antidepressant efficacy.

Adenosine Triphosphate↗
PubMed2000

Assessment of GABA concentration in human brain using two-dimensional proton magnetic resonance spectroscopy.

A quantitative method to assess in vivo brain gamma-aminobutyric acid (GABA) levels is proposed using a J-resolved, two-dimensional (2D) magnetic resonance spectroscopy (MRS) technique. Localized, J-resolved 2D MR spectra were obtained from a 12-cm(3) voxel in the occipital lobe of 36 healthy volunteers (18 male and 18 female, age: 25.1+/-4.8 years). Based on phantom measurements, a GABA resonance peak located at 2.94 ppm, 7.45 Hz, in J-resolved 2D MRS overlaps the least with other resonance peaks which arise from N-acetylaspartate, choline, creatine, glutamate and glutamine. Measurements of this resonance peak yield in vivo GABA concentrations of 1.01+/-0.36 micromol/cm(3) for male and 1.16+/-0.43 micromol/cm(3) for female volunteers, without correction for T1 and T2 relaxation effects. These results are in good agreement with previously reported data and suggest that, with further development, 2D MRS may provide a practical means to estimate the concentration of this important neurotransmitter.

Creatine↗
PubMed2000

Proton magnetic resonance spectroscopy of human basal ganglia: response to cocaine administration.

BACKGROUND: Proton magnetic resonance spectroscopy was used to determine the effects of intravenous cocaine or placebo administration on human basal ganglia water and metabolite resonances. METHODS: Long echo time, proton magnetic resonance spectra of water and intracellular metabolites were continuously acquired from an 8-cm(3) voxel centered on the left caudate and putamen nuclei before, during, and after the intravenous administration of cocaine or a placebo in a double-blind manner. RESULTS: Cocaine, at both 0.2 and 0.4 mg/kg, did not alter the peak area for water. Cocaine at 0.2 mg/kg induced small and reversible increases in choline-containing compounds and N-acetylaspartate peak areas. Cocaine at 0.4 mg/kg induced larger and more sustained increases in choline-containing compounds and N-acetylaspartate peak areas. No changes in either water or metabolite resonances were noted following placebo administration. CONCLUSIONS: These increases in choline-containing compounds and N-acetylaspartate peak areas may reflect increases in metabolite T2 relaxation times secondary to osmotic stress and/or increased phospholipid signaling within the basal ganglia following cocaine administration. This is the first report of acute, drug-induced changes in the intensity of human brain proton magnetic resonance spectroscopy resonance areas.

Adult↗
PubMed2000

The McLean-Harvard first-episode project: 6-month symptomatic and functional outcome in affective and nonaffective psychosis.

BACKGROUND: The McLean-Harvard First-Episode Project recruited affective and nonaffective patients at their first lifetime psychiatric hospitalization. METHODS: Baseline evaluation and 6-month follow-up in 257 cases yielded recovery outcomes defined by syndromal (absence of DSM-IV criteria for a current episode) and functional (vocational and residential status at least at baseline levels) status. Time to recovery was assessed by survival analysis, and risk factors by multivariate logistic regression. RESULTS: Syndromal recovery was attained by 77% of cases over an average of 84 days. By diagnostic group, syndromal recovery rates ranked (p = .001) major affective disorders (81%) > nonaffective acute psychoses (74%) > schizoaffective disorders (70%) > schizophrenia (36%). Functional recovery was significantly associated to syndromal recovery, diagnosis, shorter hospitalization normalized to year, and older age at onset. Average hospital stay declined across the study period, but recovery did not vary with year of entry. CONCLUSIONS: Syndromal recovery was achieved by nearly one half of patients within 3 months of a first lifetime hospitalization for a psychotic illness, but functional recovery was not achieved by 6 months in nearly two thirds of patients who had attained syndromal recovery.

Acute Disease↗
PubMed2000

Neuroimaging in bipolar disorder: what have we learned?

New technologies are offering increasingly powerful means to obtain structural, chemical, and functional images of the brain during life, often without the use of ionizing radiation. Bipolar disorder, with its clear physiologic features, would appear to be a prime candidate for the application of current brain imaging; however, only a modest number of studies have been reported to date, and most studies have small sample sizes and heterogeneous subject groups. Nonetheless, there are a few consistent findings among these studies, including the following: 1) Structural imaging studies suggest an increased number of white matter hyperintensities in patients with bipolar disorder. These may be lesions unique to bipolar disorder and its treatment, or related to cardiovascular risk factors, which are more common in bipolar patients. Decreased cerebellar size and anomalies of cerebellar blood volume have also been reported. Increased sulcal prominence and enlargement of the lateral and third ventricles are less consistently observed findings. 2) Spectroscopic imaging suggests abnormalities of metabolism of choline-containing compounds in symptomatically ill bipolar patients and, possibly, treatment-induced changes in choline- and myoinositol-containing compounds. Each of these groups of metabolites serves as a component of membrane phospholipids and cellular second-messenger cycles. 3) Metabolic and blood flow studies provide evidence for decreased activity of the prefrontal cortex (PFC) in bipolar patients during depression. It is not clear if these changes are restricted to particular subregions of the PFC, nor if they are reversed with mania. No single pathophysiologic mechanism yet explains these findings, although all might be due to regional alterations in cellular activity and metabolism or changes in cell membrane composition and turnover. The development of imaging technologies has far outpaced their use in bipolar disorder. The promise of future studies is great, with more powerful magnetic resonance scanners, additional ligands for positron emission tomography and single photon emission computed tomography imaging, and improved image generation and processing already available.

Bipolar Disorder↗
PubMed2000

Choline, myo-inositol and mood in bipolar disorder: a proton magnetic resonance spectroscopic imaging study of the anterior cingulate cortex.

OBJECTIVES: Alterations in choline and myo-inositol metabolism have been noted in bipolar disorder, and the therapeutic efficacy of lithium in mania may be related to these effects. We wished to determine the relationship between anterior cingulate cortex choline and myo-inositol levels, assessed using proton magnetic resonance spectroscopic imaging (MRSI), and mood state in subjects with bipolar disorder. METHODS: Serial assessments of anterior cingulate cortex choline and myo-inositol metabolism were performed in nine subjects with bipolar disorder, taking either lithium or valproate, and 14 controls. Each bipolar subject was examined between one and four times (3.1 +/- 1.3). On the occasion of each examination, standardized ratings of both depression and mania were recorded. RESULTS: In the left cingulate cortex, the bipolar subjects' depression ratings correlated positively with MRSI measures of Cho/Cr-PCr. In the right cingulate cortex, the Cho/Cr-PCr ratio was significantly higher in subjects with bipolar disorder compared with control subjects. In addition, bipolar subjects not taking antidepressants had a significantly higher right cingulate cortex Cho/Cr-PCr ratio compared with patients taking antidepressants or controls. No clinical or drug-related changes were observed for the Ino/Cr-PCr ratio. CONCLUSIONS: The results of this study suggest that bipolar disorder is associated with alterations in the metabolism of cytosolic, choline-containing compounds in the anterior cingulate cortex. As this resonance arises primarily from phosphocholine and glycerophosphocholine, both of which are metabolites of phosphatidylcholine, these results are consistent with impaired intraneuronal signaling mechanisms.

Adult↗
PubMed2000

Two-year syndromal and functional recovery in 219 cases of first-episode major affective disorder with psychotic features.

OBJECTIVE: Psychotic affective disorders are the most prevalent idiopathic psychoses, but their outcome from onset has rarely been studied. In this study, the authors determined the rate and latency of syndromal recovery and rates of functional recovery after first lifetime hospitalization in patients with first-episode psychotic affective disorders. METHOD: From first lifetime hospitalization in 1989-1996, 219 patients with a DSM-IV psychotic affective illness were assessed at intervals over 24 months. Time to syndromal recovery (no longer meeting DSM-IV episode criteria) was assessed by survival analysis, and functional recovery (regaining baseline vocational and residential status) was rated. Factors associated with recovery were identified by bivariate and multivariate methods. RESULTS: By 3, 6, 12, and 24 months after first hospitalization, syndromal recovery was attained by 65.1%, 83.7%, 91.1%, and 97.5%, respectively, of subjects. Time to syndromal recovery (6.1 weeks to 50% of subjects recovered) was shorter for patients who had bipolar disorder, were married, were age 30 or older at onset, lacked comorbidity, required relatively brief hospitalization, and received fewer medicines. Functional recovery by 6 (30.4%) and 24 months (37. 6% of patients) was 2.6-2.7 times less likely than syndromal recovery; 63.1% of those recovering syndromally did not recover functionally by 2 years. Functional recovery was associated with older age at onset and shorter hospitalization. Annual recovery rates remained stable as mean hospital length of stay decreased 3. 6-fold over the 8-year study period. CONCLUSIONS: Syndromal recovery was attained by most psychotic affective disorder patients soon after hospitalization, but only one-third recovered functionally by 24 months. The findings suggest that these very common psychotic illnesses can carry a grave functional prognosis from the initial episode and first hospitalization.

Adolescent↗
PubMed2000

Brain kinetics of paroxetine and fluoxetine on the third day of placebo substitution: a fluorine MRS study.

OBJECTIVE: This study tested whether a relationship exists between concentration and response following discontinuation of selective serotonin reuptake inhibitors. METHOD: Eight patients with remitted major depression who were taking 20 mg/day of either fluoxetine or paroxetine underwent placebo substitution for 3 days. Serum drug and brain fluorine levels were obtained before and after placebo substitution. RESULTS: With placebo substitution, a mean of 88% (SD=13%) of brain fluorine signal from fluoxetine (plus fluorinated metabolites) remained, compared with a mean of 38% (SD=17%) of the brain fluorine signal from paroxetine (plus fluorinated metabolites). Among patients taking paroxetine, adverse events during placebo substitution correlated highly with steady-state brain drug levels. CONCLUSIONS: The correlation of clinical effects with brain drug levels in the paroxetine group suggests that relationships between drug response and brain drug concentrations merit further investigation.

Adult↗