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Biomedical subjects

James C Ritchie

Publications and source records attributed to James C Ritchie.

18 recordsLinked to original sources
PubMed2006

Proteomics: a new diagnostic frontier.

BACKGROUND: Analysis of proteins has been an integral part of the field of clinical chemistry for decades. Recent advances in technology and complete identification of the human genome sequence have opened up new opportunities for analysis of proteins for clinical diagnostic purposes. METHODS: Content of a recent conference of proteomics is summarized. RESULTS: New analytical methods allow the simultaneous analysis of a large number of proteins in biological fluids such as serum and plasma, offering partial views of the complete set of proteins or proteome. Plasma presents many analytical challenges, such as the complexity of components, predominance of a few major components, and the large concentration range of components, but the number of proteins that can be detected in plasma has expanded dramatically from hundreds to thousands. At the same time, there is increased capability to detect structural variations of proteins. Recent studies also identified the presence of complex sets of small protein fragments in plasma. This set of protein fragments, the fragmentome or peptidome, is potentially a rich source of information about physiologic and disease processes. CONCLUSIONS: Advances in proteomics offer great promise for the discovery of markers that might serve as the basis for new clinical laboratory tests. There are many challenges, however, in the translation of newly discovered markers into clinical laboratory tests.

Biomarkers↗
PubMed2006

Proteomic analysis of cerebrospinal fluid discriminates malignant and nonmalignant disease of the central nervous system and identifies specific protein markers.

CNS diseases are often accompanied by changes in the protein composition of cerebrospinal fluid (CSF). SELDI-TOF-MS provides an approach for identifying specific protein markers of disease in biological fluids. We compared the CSF proteomes from patients with neoplastic and reactive/inflammatory CNS diseases to identify potential biomarkers. SELDI-TOF-MS was performed on CSF derived from lumbar puncture of 32 patients, including 10 with CNS malignancies, 12 with inflammatory or reactive conditions, and 10 with unknown CNS disease. Using the SAX-2 (strong anionic exchange) chip, we uncovered three conserved protein peak ranges within each disease category. For neoplastic diseases, we identified conserved peaks at 7.5-8.0 kDa (9/10 samples), 15.1-15.9 kDa (8/10 samples), and 30.0-32.0 kDa (5/10 samples). In reactive/inflammatory diseases, conserved peaks were found at 6.7-7.1 kDa (10/12 samples), 11.5-11.9 kDa (12/12 samples), and 13.3-13.7 kDa (9/12 samples). A protein from the 30.0 to 32.0 kDa peak range found in neoplastic CSF was identified by MALDI analysis as carbonic anhydrase, a protein overexpressed in many malignancies including high-grade gliomas. Similarly, cystatin C was identified in the 13.3-13.7 kDa peak range in non-neoplastic CSF and was most prominent in inflammatory conditions. Our approach provides a rational basis for identifying biomarkers that could be used for detection, diagnosis, and monitoring of CNS diseases.

Adult↗
PubMed2006

Neuropsychological impairment in bipolar disorder: the relationship with glucocorticoid receptor function.

OBJECTIVE: Basal levels of glucocorticoids, such as cortisol, are generally unaltered in bipolar disorder. However, neuroendocrine tests of glucocorticoid receptor (GR) function such as the dexamethasone suppression test (DST) are frequently abnormal. Neuropsychological impairment is well documented in healthy volunteers after administration of glucocorticoids and in patients with bipolar affective disorder. This suggests a potential link between neuropsychological and hypothalamic-pituitary-adrenal axis function. We examined the hypothesis that neuropsychological impairment in bipolar disorder is associated with abnormal GR function. METHODS: Seventeen euthymic bipolar patients and 16 controls completed tests of verbal declarative and working memory (WM) tests and the DST. The correlation between neuroendocrine and neuropsychological function was examined. RESULTS: Bipolar patients made significantly more errors of omission and commission on the WM paradigm and demonstrated impaired verbal recognition memory. Patients' post-dexamethasone cortisol correlated with WM commission errors (r(s) = 0.64, p = 0.0006). No such relationship was evident in controls. CONCLUSION: Deficits in declarative memory and WM are evident in patients with bipolar disorder. The deficit in retrieval accuracy from WM appears to be correlated with abnormal GR function.

Adolescent↗
PubMed2006

Antidepressants in amniotic fluid: another route of fetal exposure.

OBJECTIVE: The authors' goal was to determine the concentration of antidepressants in amniotic fluid during maternal treatment of depression. METHOD: Women treated with antidepressants undergoing amniocentesis for obstetrical reasons were enrolled. Antidepressant concentrations in amniotic fluid and maternal serum were determined with high-performance liquid chromatography. RESULTS: Amniotic fluid was obtained from 27 women, and the amniotic fluid's antidepressant concentrations were highly variable. For the parent compounds, the amniotic fluid concentrations of selective serotonin uptake inhibitors averaged 11.6% (SD=9.9%) of maternal serum concentrations (N=22). Amniotic fluid to maternal serum ratios were higher for venlafaxine: 172% (SD=91%) (N=3). Of interest, the amniotic fluid to maternal serum ratios for the metabolites (N=19) did not demonstrate a consistent pattern compared to the parent compound ratios. In 10 subjects, the amniotic fluid to maternal serum ratio for the metabolites was higher than the parent compound and lower in the remaining nine subjects. CONCLUSIONS: The pattern of antidepressant concentrations in amniotic fluid is similar to recent data for placental passage. Although the significance of amniotic fluid exposure remains to be determined, these results demonstrate that maternally administered antidepressants are accessible to the fetus in a manner not previously appreciated.

Amniocentesis↗
PubMed2006

Therapeutic drug monitoring of psychoactive drugs during pregnancy in the genomic era: challenges and opportunities.

Various symptoms of mental illness occur commonly during pregnancy. It is estimated that serious mental disorders, including major depression, bipolar disorder, schizophrenia, panic and other anxiety disorders, occur with a frequency of 10 to 25% in community samples of US women in their child-bearing years. As a result, approximately a third of all women take at least one psychoactive drug during pregnancy. Fetal drug exposure has been documented for all psychoactive drugs studied to date. However, the rate and extent of placental transfer within and between psychoactive drug classes remains ill defined. The contribution of various genetic factors such as the role of polymorphic drug metabolizing enzymes and drug transporters in controlling the variability of fetal drug exposure is also unclear. Therapeutic drug monitoring (TDM) has traditionally played an important role in psychiatric pharmacotherapy during pregnancy to ensure an adequate drug dose to achieve desired benefits while avoiding excessive fetal accumulation for drugs. In the genomic era, individualized treatment with specific drugs tailored to the mother's and fetus's genotype should eventually become the standard of care. Several methodological problems need to be overcome for this prediction to become reality. One approach to this goal taken by the Specialized Center of Research on Sex and Gender Factors Affecting Women's Health at the Emory University Women's Mental Health Program is described. This research is grounded on TDM of pregnant women receiving antidepressants, antipsychotics, anti-epileptic drugs and mood stabilizers. The use of pharmacokinetic and pharmacogenetic models to predict maternal plasma drug concentrations, fetal drug exposure, and maternal and neonatal outcomes, is expected to improve our understanding of dose-response relationships of psychoactive drugs in pregnancy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Placental passage of tricyclic antidepressants.

BACKGROUND: The use of antidepressants during pregnancy continues to garner considerable attention, though there are limited investigations that have sought to quantify fetal exposure. METHODS: Maternal and umbilical cord sera were collected at delivery from ten women taking nortriptyline and seven taking clomipramine. Placental passage was calculated as the ratio of umbilical cord to maternal serum concentration. Obstetrical outcome data were gathered from subjects at delivery. RESULTS: The placental passage ratio of nortriptyline and its active metabolite, cis-10-hydroxynortriptyline, were .68 +/- .40, 1.40 +/- 2.40, respectively. Clomipramine and desmethylclomipramine ratios were .60 +/- .50, .80 +/- .60. Obstetrical complications, such as pre-term delivery and pregnancy induced hypertension, were increased compared to the national average. CONCLUSIONS: The in vivo ratios of umbilical cord to maternal serum drug concentrations demonstrate considerable fetal exposure and differ greatly from previous results utilizing ex vivo perfusion.

Antidepressive Agents, Tricyclic↗
PubMed2005

Sex-related elevation in cortisol during chronic treatment with alprazolam associated with enhanced cognitive performance.

OBJECTIVE: There is evidence of more widespread use and abuse of benzodiazepines (BZPs) among elderly women. However, factors underlying this observation are poorly understood but could be related to more intense withdrawal reactions, which are a major risk factor for continued BZP use. We previously reported elevations in interdose morning plasma cortisol levels in healthy elderly individuals after chronic treatment with alprazolam, possibly consistent with increased hypothalamic-pituitary-adrenal (HPA) axis activity and drug withdrawal. In this study, we examined sex-related differences in this population. METHOD: Twenty-five cognitively intact healthy elderly (13 women and 12 men) participated in a parallel, double-blind, placebo-controlled study that included a group that received acute and chronic (3 weeks) treatment with alprazolam (0.5 mg b.i.d.). RESULTS: Elderly women, but not men, experienced significant elevations in interdose morning plasma cortisol levels over 3 weeks of chronic treatment with alprazolam (0.5 mg b.i.d.) compared to placebo. In addition, higher morning plasma cortisol levels were significantly associated with better cognitive performance but not with higher plasma drug levels or greater degree of tolerance development to an acute alprazolam challenge. CONCLUSION: Elderly females experienced a greater interdose activation of the HPA axis during treatment with therapeutic doses of alprazolam than men, which could be related to drug withdrawal.

Aged↗
PubMed2005

Testing the hypothesis that locus coeruleus hyperactivity produces depression-related changes via galanin.

This paper reviews progress made in testing the idea that depression-related behavioral changes can arise from hyperactivity of locus coeruleus (LC) neurons which consequently inhibits activity of mesocorticolimbic dopamine neurons in the ventral tegmentum (VTA) via release of galanin from terminals on LC axons in VTA. Results from pre-clinical testing are described, including the most recent findings indicating that, in an animal model that shows long-lasting symptoms of depression, recovery to normal activity in the home cage is accelerated by infusion of a galanin receptor antagonist, galantide (M15), into VTA. Data are also described suggesting that all effective antidepressant treatments decrease activity of LC neurons.

Animals↗
PubMed2005

Lithium placental passage and obstetrical outcome: implications for clinical management during late pregnancy.

OBJECTIVE: Lithium has been used during pregnancy for more than four decades, but quantification of fetal lithium exposure and clinical correlations of such exposure are limited. The study objectives were to 1) quantify the rate of lithium placental passage, 2) assess any association between plasma concentration of lithium at delivery and adverse perinatal events, and 3) determine whether lithium concentrations can be reduced by briefly suspending therapy proximate to delivery. METHOD: Maternal blood and umbilical cord blood were obtained at delivery for assay of lithium concentrations, and obstetrical outcome data were collected prospectively for 10 participants. These data were combined with results from MEDLINE and PsycINFO searches that identified 32 cases in which maternal lithium was administered throughout delivery. Statistical analysis of the pooled data was conducted. RESULTS: The ratio of lithium concentrations in umbilical cord blood to maternal blood (mean=1.05, SD=0.13) was uniform across a wide range of maternal concentrations (0.2-2.6 meq/liter). Significantly lower Apgar scores, longer hospital stays, and higher rates of CNS and neuromuscular complications were observed in infants with higher lithium concentrations (>0.64 meq/liter) at delivery. Withholding lithium therapy for 24-48 hours before delivery resulted in a 0.28 meq/liter reduction in maternal lithium concentration. CONCLUSIONS: Lithium completely equilibrates across the placenta. Higher lithium concentrations at delivery are associated with more perinatal complications, and lithium concentrations can be reduced by brief suspension of therapy proximate to delivery. Treatment guidelines are proposed to improve neonatal well-being when lithium use is indicated in late pregnancy.

Apgar Score↗
PubMed2005

Steady-state serum concentrations of progesterone following continuous intravenous infusion in patients with acute moderate to severe traumatic brain injury.

Progesterone (PG) has been shown to provide substantial neuroprotection after traumatic brain injury (TBI) in multiple animal models. As a first step in assessing applicability to humans, the authors examined the effects of acute TBI and extracranial trauma on the pharmacokinetics of PG given by intravenous infusion. Multiple blood samples were obtained from 11 female and 21 male trauma patients receiving PG and 1 female and 3 male patients receiving placebo infusions for 72 hours. Values for C(SS), CL, t(1/2), and Vd were obtained using AUC((0-72)) and postinfusion blood samples. C(SS) values were 337 +/- 135 ng/mL, which were significantly lower than the target concentration of 450 +/- 100 ng/mL. The lower C(SS) is attributed to the CL, which was higher than anticipated. In addition, t(1/2) was longer and V(d) was higher than anticipated. These results demonstrate that stable PG concentrations can be rapidly achieved following TBI.

Area Under Curve↗
PubMed2004

Interdose elevation in plasma cortisol during chronic treatment with alprazolam but not lorazepam in the elderly.

Benzodiazepines (BZPs) have been shown to reduce hypothalamic-pituitary-adrenal (HPA) axis activity acutely in normal humans. In contrast, the effects of chronic BZP treatment on the HPA axis have not been well studied, especially in the geriatric population. This study examined the acute and chronic effects (3 weeks) of alprazolam and lorazepam on plasma cortisol in 68 subjects (60-83 years) who received 0.25 or 0.50 mg b.i.d. alprazolam, or 0.50 or 1.0 mg b.i.d. lorazepam, or placebo orally according to a randomized, double-blind, placebo-controlled parallel design. Memory assessment and blood samples for plasma cortisol were obtained prior to the morning dose on days 0, 7, 14, and 21, and at 1, 2.5, and 5 h postdrug on days 0 and 21. Assessments of anxiety and depression were carried out at days 0, 7, 14, and 21 before drug administration. Plasma cortisol was affected compared to placebo only by the 0.5 mg alprazolam dose. During the first and the last day of treatment, there was a significant drop in cortisol at 2.5 h after alprazolam compared to placebo. The predose cortisol levels increased significantly during chronic alprazolam treatment, and correlations were found between these cortisol changes and changes in depression, anxiety, and memory scores. These findings suggest that even a short period of chronic treatment with alprazolam, but not lorazepam, may result in interdose HPA axis activation in the elderly, consistent with drug withdrawal. If confirmed, this effect may contribute to an increased risk for drug escalation and dependence during chronic alprazolam treatment.

Aged↗
PubMed2004

A novel system for the determination of antidepressant concentrations in human breast milk.

The high incidence of psychiatric illness in the postpartum period and the increasing percentage of women who breastfeed has focused attention on the treatment of breastfeeding women with psychotropic medications and, additionally, the exposure of nursing infants to these medications. Consequently, there has been an increased effort to develop standardized methods for quantifying psychotropic medications in breast milk. This paper details a novel method for quantifying the concentrations of multiple selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) in breast milk. The method consists of a common liquid/liquid and solid-phase extraction followed by HPLC separation on a common column and UV detection. Assay system 1 measures fluoxetine, norfluoxetine, fluvoxamine, and paroxetine; assay 2 measures sertraline and desmethylsertraline; and assay 3 measures the TCAs including doxepin, nordoxepin, desipramine, imipramine, nortriptyline, and amitriptyline. The method is shown to be a highly accurate and precise technique for measuring 12 different antidepressants in human breast milk and to be free of the matrix effects often encountered in breast milk drug analyses.

Antidepressive Agents↗
PubMed2004

Hypothalamic-pituitary-adrenal axis function in patients with bipolar disorder.

BACKGROUND: Hypothalamic-pituitary-adrenal (HPA) axis function, as variously measured by the responses to the combined dexamethasone/corticotrophin-releasing hormone (dex/CRH) test, the dexamethasone suppression test (DST) and basal cortisol levels, has been reported to be abnormal in bipolar disorder. AIMS: To test the hypothesis that HPA axis dysfunction persists in patients in remission from bipolar disorder. METHOD: Salivary cortisol levels and the plasma cortisol response to the DST and dex/CRH test were examined in 53 patients with bipolar disorder, 27 of whom fulfilled stringent criteria for remission, and in 28 healthy controls. Serum dexamethasone levels were measured. RESULTS: Patients with bipolar disorder demonstrated an enhanced cortisol response to the dex/CRH test compared with controls (P=0.001). This response did not differ significantly between remitted and non-remitted patients. These findings were present after the potentially confounding effects of dexamethasone levels were accounted for. CONCLUSIONS: The dex/CRH test is abnormal in both remitted and non-remitted patients with bipolar disorder. This measure of HPA axis dysfunction is a potential trait marker in bipolar disorder and thus possibly indicative of the core pathophysiological process in this illness.

Adult↗
PubMed2003

Action of three ectopeptidases on corticotropin-releasing factor: metabolism and functional aspects.

Using purified enzyme preparations, we investigated the actions of angiotensin-converting enzyme, aminopeptidase N, and endopeptidase 24.11 on corticotropin-releasing factor (CRF). The effects of inhibition of these enzymes on CRF action in rat anterior pituitary cultures were also determined. Finally, specific inhibitors were used to evaluate ectopeptidase action on the regional brain metabolism of CRF. K(m) values for CRF were 165, 90, and 42 microM for angiotensin-converting enzyme, aminopeptidase N, and endopeptidase 24.11, respectively. A CRF metabolite profile for each enzyme was determined. In pituitary cultures, inhibition of endopeptidase 24.11 and aminopeptidase N potentiated CRF-stimulated release of adrenocorticotropic hormone (ACTH). In rat pituitary and hypothalamus membrane preparations, specific inhibitor experiments indicated that CRF hydrolysis involved members of the neutral endopeptidase and aminopeptidase enzyme families. In cortex membranes, similar peptidase inhibition was without effect. These data support the hypothesis that ectopeptidases play a major role in CRF metabolism and biological function.

Adrenocorticotropic Hormone↗
PubMed2003

The pharmacokinetics of sertraline excretion into human breast milk: determinants of infant serum concentrations.

BACKGROUND: The purpose of this study was to attain a new landmark in the area of selective serotonin reuptake inhibitor therapy during lactation by establishing a basis for interpreting infant serum concentrations and for minimizing infant exposure in the absence of treatment-emergent side effects. METHOD: Breast milk and paired maternal and infant sera were collected following maternal treatment with sertraline monotherapy (25-200 mg/day) administered once daily. Sertraline and its major metabolite were measured in breast milk and serum samples using high-performance liquid chromatography with UV detection (limit of detection = 2 ng/mL). RESULTS: Twenty-six nursing women with DSM-IV major depressive disorder participated in the study; the mean (SD) daily sertraline dose was 123.9 (62.8) mg/day. Fifteen women submitted 182 breast milk samples for analysis of gradient (foremilk to hindmilk) and time course of medication excretion. The milk/plasma ratio was highly variable (range, 0.42-4.81). A significant gradient and time course of excretion for both sertraline (p <.001 for both) and desmethylsertraline (p <.001 for gradient and p <.046 for time course) were observed, with the highest concentrations observed in the hindmilk 8 to 9 hours after maternal ingestion. Mathematical modeling of sertraline and desmethylsertraline excretion revealed that discarding breast milk 9 hours after maternal dose decreased the infant daily dose of sertraline by a mean of 17.1% (1.8%). Twenty-two mother/infant sera pairs were obtained. Sertraline was detectable in 4 infants (18% of sample), and desmethylsertraline was found in 11 infants (50% of sample). The mean (SD) maximum calculated nursing infant dose of sertraline, 0.67 (0.61) mg/day, and desmethylsertraline, 1.44 (1.36) mg/day, represented 0.54% (0.49%) of the maternal daily dose. The maximum infant dose of desmethylsertraline (p <.002) significantly correlated with infant serum desmethylsertraline concentrations (ng/mL). In contrast, maternal daily dose, duration of medication exposure, and infant age and weight at sampling did not correlate with either detectability (< 2 ng/mL vs. > or = 2 ng/mL) or absolute concentrations (ng/mL) in infant serum. No adverse events were reported or documented in any infant. CONCLUSION: These results extend previous studies by demonstrating the utility of breast milk analysis in interpreting infant serum concentrations and minimizing infant exposure.

Breast Feeding↗
PubMed2002

Cerebrospinal fluid corticotropin-releasing factor (CRF) and vasopressin concentrations predict pituitary response in the CRF stimulation test: a multiple regression analysis.

There is considerable evidence that stress-related psychiatric disorders, including depression and post-traumatic stress disorder (PTSD), are associated with hypersecretion of corticotropin-releasing factor (CRF) within the central nervous system (CNS). One line of evidence that is consistent with central CRF hypersecretion in these disorders is the blunted adrenocorticotropin hormone (ACTH) response to intravenous CRF administration, likely a consequence, at least in part, of downregulation of anterior pituitary CRF receptors. The present study tests the hypothesis that elevated cerebrospinal fluid (CSF) concentrations of CRF and a secondary ACTH secretagogue, arginine vasopressin (AVP), are associated with diminished adenohypophyseal responses in a standard CRF stimulation test. CSF concentrations of CRF and AVP, and plasma ACTH responses to the administration of 1 microg/kg ovine CRF (oCRF) were measured in healthy adult women with and without current major depression and/or a history of significant childhood abuse. The primary outcome measure was ACTH area under the curve (AUC) in the CRF stimulation test. Multiple linear regression was performed to identify the impact of CSF CRF and AVP concentrations upon the pituitary response to CRF stimulation. The regression model explained 56.5% of the variation in the ACTH response to CRF stimulation. The relationship of CSF concentrations of CRF to ACTH responses to CRF were best described by a third-order function that was inversely correlated over most of the range of studied values. The association of ACTH response with CSF concentration of AVP and the dose of oCRF followed second-order kinetics. These findings support the hypothesis that central CRF hypersecretion is associated with a blunted ACTH response to exogenously administered CRF, explaining almost 60% of the variation in the ACTH response to CRF.

Adrenocorticotropic Hormone↗