Biomedical subjects

B J Carroll

Publications and source records attributed to B J Carroll.

At least 19 recordsLinked to original sources

PubMed2004

Fine mapping of the tomato I-3 gene for fusarium wilt resistance and elimination of a co-segregating resistance gene analogue as a candidate for I-3.

The I-3 gene from the wild tomato species Lycopersicon pennellii confers resistance to race 3 of the devastating vascular wilt pathogen Fusarium oxysporum f. sp. lycopersici. As an initial step in a positional cloning strategy for the isolation of I-3, we converted restriction fragment length polymorphism and conserved orthologue set markers, known genes and a resistance gene analogue (RGA) mapping to the I-3 region into PCR-based sequence characterised amplified region (SCAR) and cleaved amplified polymorphic sequence (CAPS) markers. Additional PCR-based markers in the I-3 region were generated using the randomly amplified DNA fingerprinting (RAF) technique. SCAR, CAPS and RAF markers were used for high-resolution mapping around the I-3 locus. The I-3 gene was localised to a 0.3-cM region containing a RAF marker, eO6, and an RGA, RGA332. RGA332 was cloned and found to correspond to a putative pseudogene with at least two loss-of-function mutations. The predicted pseudogene belongs to the Toll interleukin-1 receptor-nucleotide-binding site-leucine-rich-repeat sub-class of plant disease resistance genes. Despite the presence of two RGA332 homologues in L. esculentum, DNA gel blot and PCR analysis suggests that no other homologues are present in lines carrying I-3 that could be alternative candidates for the gene.

Amino Acid Sequence↗

PubMed2004

Application of the quartz crystal microbalance to the evaporation of colloidal suspension droplets.

An investigation into the evaporation of sessile droplets of latex and clay particle suspensions is presented in this work. The quartz crystal microbalance (QCM) has been used to study the interfacial phenomena during the drying process of these droplets. Characteristic changes of the crystal oscillating frequency and crystal resistance (damping of the oscillating energy) have been observed and related to the different stages of the evaporation process. Measurements have been made for latex particle sizes from 1.9 to 10 microm and for rough and polished crystals using drops from 0.3 to 1.5 microL. The behavior of the QCM is shown to depend strongly on the size of particles present and on the morphology of the crystal surface. One of the most striking features is a drastic damping of the oscillation energy and corresponding rise in frequency observed during the final stages of evaporation, particularly for the clay suspensions.

Journal Article↗

PubMed2002

Inheritance and mapping of 11 avirulence genes in Phytophthora sojae.

Two new crosses involving four races (races 7, 16, 17, and 25) of the soybean root and stem rot pathogen Phytophthora sojae were established (7/16 cross; 17/25 cross). An F2 population derived from each cross was used to determine the genetic basis of avirulence towards 11 different resistance genes in soybean. Avirulence was found to be dominant and determined by a single locus for Avr1b, 1d, 1k, 3b, 4, and 6, as expected for a simple gene-for-gene model. We also observed several cases of segregation, inconsistent with a single dominant gene being solely responsible for avirulence, which suggests that the genetic background of the different crosses can affect avirulence. Avr4 and 6 cosegregated in both the 7/16 and 17/25 crosses and, in the 7/16 cross, Avr1b and 1k were closely linked. Information from segregating RAPD, RFLP, and AFLP markers screened on F2 progeny from the two new crosses and two crosses described previously (a total of 212 F2 individuals, 53 from each cross) were used to construct an integrated genetic linkage map of P. sojae. This revised genetic linkage map consists of 386 markers comprising 35 RFLP, 236 RAPD, and 105 AFLP markers, as well as 10 avirulence genes. The map is composed of 21 major linkage groups and seven minor linkage groups covering a total map distance of 1640.4cM.

Algal Proteins↗

PubMed2002

Thyroid function in mixed and pure manic episodes.

OBJECTIVES: Associations of both overt thyroid disease as well as subclinical thyroid abnormalities with affective disorders have been well established. Similar associations have been reported with mixed mania and rapid cycling bipolar disorder. We tested for differences in overt and subclinical thyroid disease and subclinical differences in a large series of bipolar patients examined during mixed or pure manic episodes. METHODS: Rates of previously diagnosed thyroid disease were compared by sex, race and manic subtype (mixed versus pure) in 443 patients. Serum thyroid stimulating hormone (TSH) and free thyroxine (FT4) concentrations obtained from patients with no clinical thyroid disease collected during manic and mixed bipolar episodes were compared using ANOVA statistics. Race was also included in the model and age was covaried. RESULTS: Rates of thyroid disease, in particular hypothyroidism, were higher in females and white people, and increased with advancing age. No differences were noted between subjects sampled during mixed or pure manic episodes. In patients with no history of thyroid disease, serum TSH and FT4 concentrations did not differ between manic subtypes or between sexes. TSH levels however, were significantly lower in African Americans. CONCLUSIONS: We did not confirm past reports of associations of overt or subclinical thyroid disease with mixed manic episodes. African Americans had significantly lower serum TSH concentrations than white people, while FT4 levels did not differ.

Adult↗

PubMed2001

MRI correlates of suicide attempt history in unipolar depression.

BACKGROUND: Suicide represents a major health problem in the United States, and prediction of suicide attempts is difficult. No structural neuroimaging studies have been done to specifically examine findings in patients who have attempted suicide. The objective of this study was to compare MRI findings in unipolar patients with and without a history of a suicide attempt. METHODS: In this post hoc analysis, 20 unipolar subjects with a history of a suicide attempt were matched by age and gender to unipolar subjects without a history of an attempt. Subjects were also matched on parameters such as cardiovascular history, electroconvulsive treatment history, and history of psychosis. Subjects with a history of any neurologic condition were excluded. There were no significant differences in age of onset of depression, number of episodes of depression, and Hamilton Depression scores between the two groups. T2-weighted magnetic resonance imaging (MRI) scans were rated using the Coffey and Boyko rating scales. RESULTS: Unipolar patients with a history of a suicide attempt demonstrated significantly more subcortical gray matter hyperintensities compared with patients without such a history. CONCLUSIONS: Patients with abnormal MRI findings may be at higher risk for mood disorders and suicide attempts because of disruption of critical neuroanatomic pathways. Gray matter hyperintensities in the basal ganglia may be especially associated with risk for suicide attempts.

Aged↗

PubMed2001

A prospective study of inter-episode consistency of manic and mixed subtypes of bipolar disorder.

BACKGROUND: Few studies have compared symptom presentations across manic or mixed episodes in manic-depressive patients. METHODS: In the current study we report on symptom presentations of 68 prospectively-evaluated subjects diagnosed with Bipolar Disorder during two discrete manic or mixed episodes. Each episode was categorized using DSM-IIIR criteria for Bipolar Disorder, manic or mixed, as well as a less restrictive definition for manic and mixed states derived from receiver operating characteristic (ROC) analysis of symptoms. RESULTS: The occurrence of mixed bipolar episodes was not random using either the DSM-IIIR or ROC-derived definitions of mixed episodes. LIMITATIONS: Subjects were not all fully medication-free at the time of evaluation which may have altered symptom presentation. The total duration of the study was limited, with the longest inter-episode interval under 6 years. CONCLUSIONS: Although there was variability in mixed symptomatology between episodes, the occurrence of mixed episodes was not random. Manic and mixed episodes tend to recur true to type.

Adolescent↗

PubMed2001

Frequencies of signs and symptoms in mixed and pure episodes of mania: implications for the study of manic episodes.

1. In a previous report the authors compared the frequency of 20 classical and mixed manic signs and symptoms in subjects meeting DSM-III-R criteria for Bipolar Disorder, manic or mixed. In that report, the authors commented that a possible limitation of the study was the diagnosis of mixed and pure mania using DSM-III-R criteria that may be too rigid The authors now address that issue, adopting a ROC-derived definition of mixed mania 2. Three hundred sixty-three subjects meeting DSM-III-R criteria for Bipolar Disorder, manic or mixed, were evaluated by rating 20 signs and symptoms of mania. The frequencies of these signs and symptoms were computed and compared for both mixed and pure subtypes, determined by the ROC-derived definition. 3. Mood lability, dysphoric mood, guilt, anxiety, and suicidality were more frequently observed in the mixed manic group In contrast, euphoria and grandiosity were more frequently observed in the pure manic group. Nonetheless, non-trivial rates of dysphoric mood, irritability and anxiety were still observed in the pure groups, despite the adoption of a less restrictive definition of mixed states. The current results are similar to the results obtained using DSM-III-R criteria for Bipolar Disorder, manic and mixed. Although rates of dysphoric mood, anxiety, lability, guilt and suicidality were lower in the manic group, each of these symptoms may be observed in pure manic episodes, underscoring the importance of recognition and evaluation of these features in formal studies of "pure" as well as mixed manic episodes.

Adult↗

PubMed2001

Serum melanotransferrin, p97 as a biochemical marker of Alzheimer's disease.

The protein melanotransferrin (p97) is associated with the brain lesions of Alzheimer's disease (AD) and is a potential marker of the disorder. We measured serum p97 concentrations in 211 subjects: 71 patients with AD, 56 patients with non-AD-type dementia, and 84 normal control subjects. Serum p97 concentrations were elevated 3- to 4-fold in AD (median 15.00 pg/microl, interquartile range 10.20-17.00 pg/microl) as compared to non AD dementia (2.85 pg/microl, 1.93-7.15 pg/microl) and normal controls (3.20 pg/microl, 2.55-3.95 pg/microl). The mean elevation was significant at 13.54 +/- 3.72 pg/microl, even in the 38 subjects with mild AD (CDR stage 0.5-1). Receiver operating characteristic analyses confirmed an optimal diagnostic threshold of 10.0 pg/microl, which yielded over-all accuracy of 0.882 to 0.915. Serum p97 is a candidate marker of AD, even in the early stage when clinical diagnosis is most uncertain.

Adult↗

PubMed2001

Subtypes of mania determined by grade of membership analysis.

Classical descriptions of mania subtypes extend back to Kraepelin; however, in marked contrast to the study of depression subtypes, validation of mania subtypes by multivariate statistical methods has seldom been attempted. We applied Grade of Membership (GOM) analysis to the rated clinical features of 327 inpatients with DSM-III-R mania diagnoses. GOM is a type of latent structure multivariate analysis, which differs from others of this type in making no a priori distributional assumptions about groupings. We obtained 5 GOM Pure Types with good face validity. The major Kraepelinian forms of "hypomania," "acute mania," "delusional mania," and "depressive or anxious mania" were validated. The major new finding is of two mixed mania presentations, each with marked lability of mood. The first of these displayed a dominant mood of severe depression with labile periods of pressured, irritable hostility and paranoia, and the complete absence of euphoria or humor. The second mixed mania Pure Type displayed a true, incongruous mixture of affects: periods of classical manic symptoms with euphoria, elation, humor, grandiosity, psychosis, and psychomotor activation, switching frequently to moderately depressed mood with pressured anxiety and irritability. This multivariate analysis validated classical clinical descriptions of the major subtypes of mania. Two distinct forms of mixed manic episodes were identified. DSM-III-R criteria did not reliably identify either of these two natural groups of mixed bipolar patients. As occurs in depression, this clinical heterogeneity of mania may influence response to drug treatments.

Adolescent↗

PubMed2001

The clinical epidemiology of pure and mixed manic episodes.

INTRODUCTION: Few large clinical epidemiological studies have been undertaken comparing subjects meeting criteria for mixed and pure states of bipolar disorder. In part, the difficulty comparing these states emanates from confusion in their diagnostic separation. In the current report, we use a definition derived from receiver operating characteristic (ROC) curve analysis as an alternative to the DSM-IIIR/IV definition, and we compare the two subtypes of manic episodes. METHODS: Three hundred and sixty-six patients meeting DSM-IIIR criteria for bipolar disorder, manic or mixed, were categorized using newly described criteria for mixed states. The two subtypes were compared on demographic variables and clinical history variables, using multiple analysis of variance with post hoc univariate F tests. The same analyses were conducted using the DSM-IIIR-defined subtypes. RESULTS: Using the ROC criteria, 79 subjects (21.6%) were characterized as mixed, in contrast to 51 subjects (13.9%) using DSM-IIIR criteria for bipolar disorder, mixed. The ROC-defined mixed manic group comprised more Caucasians and more females. Age of first psychiatric hospitalization was earlier and duration of illness longer in the mixed group. First episodes were unlikely to be categorized as mixed (< 5%). When the DSM-IIIR definition was employed, differences were not demonstrated. CONCLUSIONS: An earlier age of first psychiatric hospitalization and increased duration of illness, as well as a lower frequency of mixed subtype of manic episode during first hospitalization, are compatible with the view that mixed manic episodes occur more frequently later in the course of bipolar disorder. Moreover, differences in race, sex, and clinical histories of subjects in mixed episodes tend to support the separation of mixed mania as a diagnostic subtype of bipolar disorder.

Adolescent↗

PubMed2001

A DNA fingerprinting procedure for ultra high-throughput genetic analysis of insects.

Existing procedures for the generation of polymorphic DNA markers are not optimal for insect studies in which the organisms are often tiny and background molecular information is often non-existent. We have used a new high throughput DNA marker generation protocol called randomly amplified DNA fingerprints (RAF) to analyse the genetic variability in three separate strains of the stored grain pest, Rhyzopertha dominica. This protocol is quick, robust and reliable even though it requires minimal sample preparation, minute amounts of DNA and no prior molecular analysis of the organism. Arbitrarily selected oligonucleotide primers routinely produced approximately 50 scoreable polymorphic DNA markers, between individuals of three independent field isolates of R. dominica. Multivariate cluster analysis using forty-nine arbitrarily selected polymorphisms generated from a single primer reliably separated individuals into three clades corresponding to their geographical origin. The resulting clades were quite distinct, with an average genetic difference of 37.5 +/- 6.0% between clades and of 21.0 +/- 7.1% between individuals within clades. As a prelude to future gene mapping efforts, we have also assessed the performance of RAF under conditions commonly used in gene mapping. In this analysis, fingerprints from pooled DNA samples accurately and reproducibly reflected RAF profiles obtained from individual DNA samples that had been combined to create the bulked samples.

Animals↗

PubMed2001

Corticotropin secretory dynamics in humans under low glucocorticoid feedback.

To explore the mechanisms of homeostatic adaptation of the hypothalamo-pituitary-adrenal axis to an experimental low-feedback condition, we quantitated pulsatile (ultradian), entropic (pattern-sensitive), and 24-h rhythmic (circadian) ACTH secretion during high-dose metyrapone blockade (2 g orally every 2 h for 12 h, and then 1 g every 2 h for 12 h). Plasma ACTH and cortisol concentrations were sampled concurrently every 10 min for 24 h in nine adults. The metyrapone regimen reduced the amplitude of nyctohemeral cortisol rhythm by 45% (P = 0.0013) and delayed the time of the cortisol maximum (acrophase) by 7.1 h (P = 0.0002). Attenuated cortisol negative feedback stimulated a 7-fold increase in the mean (24-h) plasma ACTH concentration, which rose from 24 +/- 1.6 to 169 +/- 31 pg/ml (ng/liter) (P < 0.0001). Augmented ACTH output was driven by a 12-fold amplification of ACTH secretory burst mass (integral of the underlying secretory pulse) (21 +/- 3.1 to 255 +/- 64 pg/ml; P < 0.0001), yielding a higher percentage of ACTH secreted in pulses (53 +/- 3.5 vs. 92 +/- 1.3%; P < 0.0001). There were minimal elevations in basal (nonpulsatile) ACTH secretion (by 50%; P = 0.0049) and ACTH secretory burst frequency (by 36%; P = 0.031). The estimated half-life of ACTH (median, 22 min) and the calculated ACTH secretory burst half-duration (pulse event duration at half-maximal amplitude) (median, 23 min) did not change. Hypocortisolemia evoked remarkably more orderly subordinate patterns of serial ACTH release, as quantitated by the approximate entropy statistic (P = 0.003). This finding was explained by enhanced regularity of successive ACTH secretory pulse mass values (P = 0.032). In contrast, there was no alteration in serial ACTH interpulse-interval (waiting-time) regularity. At the level of 24-h ACTH rhythmicity, cortisol withdrawal enhanced the daily rhythm in ACTH secretory burst mass by 29-fold, elevated the mesor by 16-fold, and delayed the acrophase by 3.4 h from 0831 h to 1154 h (each P < 10(-3)). In summary, short-term glucocorticoid feedback deprivation primarily (>97% of effect) amplifies pulsatile ACTH secretory burst mass, while minimally elevating basal/nonpulsatile ACTH secretion and ACTH pulse frequency. Reduced cortisol feedback paradoxically elicits more orderly (less entropic) patterns of ACTH release due to emergence of more regular ACTH pulse mass sequences. Cortisol withdrawal concurrently heightens the amplitude and mesor of 24-h rhythmic ACTH release and delays the timing of the ACTH acrophase. In contrast, the duration of underlying ACTH secretory episodes is not affected, which indicates that normal pulse termination may be programmed centrally rather than imposed by rapid negative feedback. Accordingly, we hypothesize that adrenal glucocorticoid negative feedback controls hypothalamo-pituitary-adrenal axis dynamics via the 3-fold distinct mechanisms of repressing the mass of ACTH secretory bursts, reducing the orderliness of the corticotrope release process, and modulating the intrinsic diurnal rhythmicity of the hypothalamo-corticotrope unit.

Adrenocorticotropic Hormone↗

PubMed2001

Substance abuse in bipolar disorder.

BACKGROUND: High rates of substance abuse have been reported in the general population, with males more often affected than females. Although high rates of substance abuse have also been reported in bipolar patients, the relationship between substance abuse and bipolar disorder has not been well characterized. METHODS: Substance abuse histories were obtained in 392 patients hospitalized for manic or mixed episodes of bipolar disorder and rates of current and lifetime abuse calculated. Analyses comparing sex, subtype (manic vs. mixed) and clinical history variables were conducted. RESULTS: Rates of lifetime substance abuse were high for both alcohol (48.5%) and drugs (43.9%). Nearly 60% of the cohort had a history of some lifetime substance abuse. Males had higher rates of abuse than females, but no differences in substance abuse were observed between subjects in manic and mixed bipolar states. Rates of active substance abuse were lower in older age cohorts. Subjects with a comorbid diagnosis of lifetime substance abuse had more psychiatric hospitalizations. CONCLUSIONS: Substance abuse is a major comorbidity in bipolar patients. Although rates decrease in older age groups, substance abuse is still present at clinically important rates in the elderly. Bipolar patients with comorbid substance abuse may have a more severe course. These data underscore the significance of recognition and treatment of substance abuse in bipolar disorder patients.

Adult↗

PubMed2000

Dexamethasone metabolism in dexamethasone suppression test suppressors and nonsuppressors.

BACKGROUND: Variable dexamethasone kinetics is a possible confound in the dexamethasone suppression test. Modifications to include dexamethasone plasma levels and specific dexamethasone "windows" have been proposed. Our study aims to validate our proposed dexamethasone windows in an independent sample of 121 subjects. METHODS: We performed dexamethasone suppression tests in 162 subjects with mixed psychiatric diagnoses. Dexamethasone levels and beta-phase half-life of dexamethasone were computed for suppressors and nonsuppressors. RESULTS: Dexamethasone levels were lower in nonsuppressors than in suppressors. Dexamethasone levels correlated inversely with cortisol levels in the total sample, but were nonsignificant or weakly associated in those samples restricted to the windows. The beta-phase half-life of dexamethasone was shorter in nonsuppressors. The dexamethasone windows were validated at 3:00 PM and 10:00 PM. We propose 4.0 ng/mL as a revised upper limit of the 8:00 AM dexamethasone window. CONCLUSIONS: The plasma dexamethasone level is confirmed as a confound in the dexamethasone suppression test through more rapid dexamethasone clearance in nonsuppressors. Application of dexamethasone windows will reduce this source of test variance.

Adrenal Cortex Function Tests↗

PubMed2000

Serotonin transporter gene polymorphism and antidepressant response.

We examined allelic polymorphisms of the serotonin transporter (5-HTT) gene and antidepressant response to 6 weeks' treatment with the selective serotonin reuptake inhibitor (SSRI) drugs fluoxetine or paroxetine. We genotyped 120 patients and 252 normal controls, using polymerase chain reaction of genomic DNA with primers flanking the second intron and promoter regions of the 5-HTT gene. Diagnosis of depression was not associated with 5-HTT polymorphisms. Patients homozygous l/l in intron 2 or homozygous s/s in the promoter region showed better responses than all others (p < 0.0001, p = 0.0074, respectively). Lack of the l/l allele form in intron 2 most powerfully predicted non-response (83.3%). Response to SSRI drugs is related to allelic variation in the 5-HTT gene in depressed Korean patients.

Adult↗

PubMed2000

Intramolecular proton transfer in the cyclization of geranylgeranyl diphosphate to the taxadiene precursor of taxol catalyzed by recombinant taxadiene synthase.

BACKGROUND: The committed step in the biosynthesis of the anticancer drug taxol in yew (Taxus) species is the cyclization of geranylgeranyl diphosphate to taxa-4(5),11(12)-diene. The enzyme taxadiene synthase catalyzes this complex olefin cation cyclization cascade involving the formation of three rings and three stereogenic centers. RESULTS: Recombinant taxadiene synthase was incubated with specifically deuterated substrates, and the mechanism of cyclization was probed using MS and NMR analyses of the products to define the crucial hydrogen migration and terminating deprotonation steps. The electrophilic cyclization involves the ionization of the diphosphate with closure of the A-ring, followed by a unique intramolecular transfer of the C11 proton to the re-face of C7 to promote closure of the B/C-ring juncture, and cascade termination by proton elimination from the beta-face of C5. CONCLUSIONS: These findings provide insight into the molecular architecture of the first dedicated step of taxol biosynthesis that creates the taxane carbon skeleton, and they have broad implications for the general mechanistic capability of the large family of terpenoid cyclization enzymes.

Alkenes↗

PubMed2000

Diagnostic depressive symptoms of the mixed bipolar episode.

BACKGROUND: There is not yet consensus on the best diagnostic definition of mixed bipolar episodes. Many have suggested the DSM-III-R/-IV definition is too rigid. We propose alternative criteria using data from a large patient cohort. METHODS: We evaluated 237 manic in-patients using DSM-III-R criteria and the Scale for Manic States (SMS). A bimodally distributed factor of dysphoric mood has been reported from the SMS data. We used both the factor and the DSM-III-R classifications to identify candidate depressive symptoms and then developed three candidate depressive symptom sets. Using ROC analysis we determined the optimal threshold number of symptoms in each set and compared the three ROC solutions. The optimal solution was tested against the DSM-III-R classification for crossvalidation. RESULTS: The optimal ROC solution was a set, derived from both the DSM-III-R and the SMS, and the optimal threshold for diagnosis was two or more symptoms. Applying this set iteratively to the DSM-III-R classification produced the identical ROC solution. The prevalence of mixed episodes in the cohort was 13.9% by DSM-III-R, 20.2% by the dysphoria factor and 27.4% by the new ROC solution. CONCLUSIONS: A diagnostic set of six dysphoric symptoms (depressed mood, anhedonia, guilt, suicide, fatigue and anxiety), with a threshold of two symptoms, is proposed for a mixed episode. This new definition has a foundation in clinical data, in the proved diagnostic performance of the qualifying symptoms, and in ROC validation against two previous definitions that each have face validity.

Adolescent↗

PubMed2000

Molecular contribution to selection of intergeneric hybrids between sugarcane and the wild species Erianthus arundinaceus.

Erianthus arundinaceus has great potential as a germplasm source for better ratoonability, vigour, tolerance to environmental stresses, and disease resistance in sugarcane. Many unsuccessful attempts have been made to introduce these characters into modern sugarcane cultivars. We report on significant progress made since molecular tools were implemented. Sequence-tagged PCR, revealing size variation in the 5S rDNA cluster, was performed on intact leaf tissue to identify genuine hybrids six weeks after germination. This early screening of seedlings avoids the loss of genuine hybrids due to competition with selfed progeny. Of 96 crosses made involving female Saccharum officinarum or sugarcane cultivars (Saccharum spp.) and male E. arundinaceus, 26 were fertile producing 1328 seedlings. Thirty-seven genuine hybrids were unequivocally identified but only 19 have survived. Genuine hybrids were produced from only three crosses, all involving S. officinarum as the female parent. Chromosome elimination was observed in all seven hybrids analyzed using genomic in situ hybridization (GISH). Very little cross-hybridization was observed between the genomes of the two species after GISH, confirming recent molecular studies which showed that E. arundinaceus is quite distant from the genus Saccharum. The major limitation in the introgression of E. arundinaceus resides now in the apparent sterility of the hybrids.

Chromosomes↗