The modulatory effect of leptin on the overall insulin production in ex-vivo normal rat pancreas.

Leptin has a modulator effect on glucose-stimulated insulin secretion. To define the influences of different glucose (4, 8, 12, and 16 mmol/L) and leptin (5, 10, 15, and 20 nmol/L) concentrations on total insulin release in ex vivo pancreatic preparations, a customized perfusion technique was used. Such a profile of concentration brought about an index for the combined effect of leptin and glucose on the production of insulin. Insulin output was measured by radioimmunoassay. Stimulated by glucose alone in the control group, insulin secretion confirmed a bi-phasic pattern. Addition of leptin in the experimental group suppressed insulin secretion compared with control. A U-shape pattern of suppression was observed when the leptin and stimulatory glucose concentrations were combined. At 12 mmol/L glucose, leptin showed maximal insulin suppression. Leptin's effect on insulin was glucose dependent and showed a reproducible U-shaped pattern of suppression, which implicated possible direct dose-dependent interaction between leptin and glucose on insulin secretion.

Factors associated with chronic depressive episodes: a preliminary report from the STAR-D project.

OBJECTIVE: To identify baseline sociodemographic and clinical factors associated with a current chronic major depressive episode (MDE). METHOD: Outpatients with major depressive disorder enrolled in 41 US primary or psychiatric care sites were divided into two groups based on self-report of current episode length (<24 or > or =24 months). Logistic regression models were used to identify factors associated with chronicity of current depressive episode. RESULTS: About 21.2% of 1380 subjects were in current, chronic MDEs. Older age, less education, lower income, no private insurance, unemployment, greater general medical illness burden, lower physical quality of life, concurrent generalized anxiety disorder, fewer prior episodes, and history of prior suicide attempts were all associated with chronic episodes. Blacks, Hispanics, and patients receiving care in primary as opposed to psychiatric care settings exhibited greater chronicity. CONCLUSION: Chronic depressive episodes are common and are associated with greater illness burden, comorbidity, socioeconomic disadvantage, and racial/ethnic minority status.

Effect of a surfactant, Tween 80, on the formation and secretion of chylomicrons in the rat.

Effects of Tween 80, a nonionic surfactant, on size and number of chylomicrons (CM) secreted during lipid absorption in the rat model are reported. Fasted rats were loaded with either 154 mM NaCl or 25% (w/w) olive oil emulsion in 154 mM NaCl with 0, 0.1, 1 or 10% (w/w) Tween 80. After 3 h, either mesenteric lymph or blood was collected and their triacylglycerol-rich lipoprotein fraction (Sf>20 and Sf>400, respectively) isolated. Triacylglycerol (TAG) and apolipoprotein B48 (apoB48) concentrations in the lipoprotein fractions were assayed and their fluxes (lymph) calculated. TAG:apoB48 ratios, indicative of CM size, were determined. The data support the hypothesis that fat loading is accommodated mainly by increased average size, rather than number, of CM. Co-administration of Tween 80 with olive oil resulted in a significant increase in CM apoB48 secretion into the mesenteric lymph duct and in an increased concentration of apoB48 in the blood (Sf>400). Also, Tween 80-treated groups exhibited smaller mean CM size relative to the olive oil only group in both lymph and blood. The observed effect on CM size and number did not appear to be dose dependent at concentrations of Tween 80 above 0.1% (w/w). Incorporation of Tween 80 in the diet at 1 or 10% (w/w) concentrations reduced the TAG concentration in the stools; however, a significant increase in water content was observed at 10% (w/w) concentration. In conclusion, Tween 80 at 1 or 10% (w/w) doses can improve the efficiency of the digestive system to absorb dietary fat but at high concentrations (10%, w/w) it appeared to have a toxic or irritating effect on the gastrointestinal system. More importantly, the effect of Tween 80 on size and number of CM is a condition that favours a delay in their clearance rate.

Management of treatment-resistant depression: psychotherapeutic perspectives.

Treatment-resistant depression is a heterogeneous condition that occurs within a psychosocial milieu. The impact of prior pharmacologic interventions may have been adversely affected by a poor therapeutic alliance, low social support, life stress, or chronic adversity and cognitive or personality factors such as neuroticism or pessimism. This article considers the psychosocial factors that predispose to treatment-resistant depression and the psychotherapeutic principles thought to be helpful in both shorter- and longer-term treatment plans. We focus on the interpersonal, cognitive, and behavioral forms of treatment that constitute the depression-focused psychotherapies, which have been studied in major depressive disorder. Also discussed are modifications in treatment planning necessary to take into account the complexity of treatment-resistant depression.

Sertraline versus imipramine to prevent relapse in chronic depression.

BACKGROUND: Chronic depressions are common, disabling and under-treated, and long-term treatment is little studied. We report the continuation phase results from a long-term treatment study. METHODS: After 12 weeks of acute phase treatment in a double-blind, randomized, parallel-group, multi-center trial of sertraline or imipramine, patients with chronic depression (> or = 2 years in major depression, or major depression superimposed on dysthymia) continued study drug for 16 weeks. Initially, 635 patients were randomized to sertraline or imipramine in a 2:1 ratio. Nonresponders after 12 weeks entered a 12-week double-blind crossover trial of the alternate medication. Entry into continuation treatment required at least a satisfactory response (partial remission) to initial or crossover treatment. RESULTS: Of 239 acute or crossover responders to sertraline, 60% entered continuation in full remission and 40% with a partial remission. These proportions were identical for imipramine patients (n = 147). For both drug groups, over two-thirds of those entering in full remission retained it. For those entering in partial remission, over 40% achieved full remission. Patients requiring crossover treatment were less likely to maintain or improve their response during continuation treatment. The two drugs did not differ significantly in response distribution, drop out rates or discontinuation due to side effects during continuation treatment. LIMITATIONS: The absence of a placebo group constrains interpretation of our results, but chronic depressions have low placebo response rates. CONCLUSIONS: Most chronic depression patients who remit with 12 weeks of sertraline or imipramine treatment maintain remission during 16 weeks of continuation treatment. Most patients with a satisfactory therapeutic response (partial remission) after 12 weeks of treatment maintain it or further improve. Patients treated with imipramine experienced more side effects, but both drugs were well tolerated.

Venlafaxine and treatment-resistant depression.

Treatment-resistant depression (TRD) is an important clinical problem. This paper briefly reviews the definition of TRD and summarizes methodological issues that pertain to treatment research. Recent studies of venlafaxine treatment for TRD also are reviewed. It is concluded that venlafaxine at higher doses is a reasonably well-tolerated and an effective alternative for patients with TRD and typically should be used before tricyclic antidepressants or monoamine oxidase inhibitors. Further research is needed to confirm the prediction that switching a SSRI nonresponder to venlafaxine is a more effective strategy than switching to a second SSRI. The relative merits of switching from a SSRI to venlafaxine versus adding a norepinephrine reuptake inhibitor also warrant careful study.

Comparison of DSM-III-R chronic major depression and major depression superimposed on dysthymia (double depression): validity of the distinction.

The nosology of chronic depression has become increasingly complex since the publication of the revised third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R; American Psychiatric Association, 1987), but there are few data available to evaluate the validity of the distinctions between the subtypes of chronic depression. The validity of the distinction between DSM-III-R chronic major depression (CMD) and major depression superimposed on dysthymia (double depression, DD) was examined. Participants were 635 patients with chronic depression in a 12-week trial of antidepressant medications. Patients with CMD, DD, and a 3rd group with a chronic major depressive episode superimposed on dysthymia (DD/CMD) were compared on demographic and clinical characteristics, family history, and response to treatment. Few differences were evident, although the depression of patients with DD/CMD tended to be more severe.

Seasonal variability of salinity, temperature, turbidity and suspended chlorophyll in the Tweed Estuary.

Results are presented from a campaign of measurements that were undertaken to examine seasonal variability in physical and chemical fluxes and processes within the Tweed Estuary during the period September 1996-August 1997. The study utilised monthly surveys, each of approximately 1 week duration. This article interprets a subset of the salinity, temperature, turbidity [suspended particulate matter (SPM) levels] and chlorophyll a data. Measurements discussed here were obtained throughout the estuary during high-speed transects that covered the region between the tidal river and the coastal zone. Longitudinal distributions of surface salinity depended strongly on freshwater runoff. During high runoff the surface salinity was low and the freshwater-saltwater interface (FSI) was located close to the mouth. The reverse was true at times of low runoff. Salinity stratification was generally strong. During the surveys, river runoff temperatures ranged from approximately 2 to 18 degrees C and coastal waters (approximately 33 salinity) from approximately 6 to 15 degrees C. Turbidity was low throughout the campaign (SPM < 30 mg l(-1)). Because of rapid flushing times (one or two tides), turbidity tended to mix conservatively between river and coastal waters. Higher coastal turbidity was associated with stronger wind events, and higher fluvial turbidity with spate events. Suspended chlorophyll a levels were usually low throughout the estuary (typically < 2 microg l(-1)) and showed large spatial variability. Because of the rapid flushing of the estuary, it is hypothesised that it was not possible for several algal cell divisions to occur before algae were flushed to the coastal zone. A 'bloom' occurred during the May 1997 survey, when chlorophyll a levels reached 14 microg l(-1). Higher chlorophyll a concentrations at that time occurred at very low salinities, indicating that these waters and algae were largely fluvially derived, and may have resulted from increasing springtime solar irradiation.

Distributions and seasonal variability of pH and alkalinity in the Tweed Estuary, UK.

Monthly axial profiles of the Tweed Estuary were carried out between July 1996 and August 1997 as part of the UK Natural Environment Research Council Land Ocean Interaction Study. During these surveys, master variables and a range of chemical constituents, including pH and total alkalinity, were measured between the mouth of the estuary, at Berwick-upon-Tweed, and the freshwater tidal reach, at Union Bridge, approximately 10 km up-estuary. Alkalinity and pH showed clear seasonal variations in values within the lower salinity region of the estuary, and these could be related largely to changes in river flows, and hence to variations in the ratios of the source waters. River waters at high flows were dominated by poorly buffered surficial runoff, and pH and alkalinity values were low; conversely at low flows, groundwaters rich in weathered bedrock ions dominated the river water, and pH and alkalinity values were significantly higher. Biological production and respiration also had an effect on this seasonal variability, although this was secondary. The behaviour of pH and alkalinity within the estuary appeared generally conservative, although apparent non-conservative distributions were observed in the freshwater tidal reach. In a number of cases this behaviour could be attributed to biological activity. Estimated values of the excess partial pressures of CO2 within the fresh-water tidal reach were low (< 4), reflecting the relatively pristine character of the Tweed. During the spring and summer, CO2 was significantly undersaturated with respect to the atmosphere; extensive production by bed-anchored macroalgae was probably the reason for this, although the effects of water column algae cannot be discounted. In winter, production was minimal and respiration more important. As a result, partial pressures within the water column increased to a maximum of approximately four times atmospheric. Only infrequently was the CO2 in equilibrium between the river and atmosphere, suggesting that the tidal reach of the Tweed is a dynamic environment with respect to carbon cycling processes.

Concentrations of suspended particulate organic carbon in the tidal Yorkshire Ouse River and Humber Estuary.

Data are presented for particulate organic carbon (POC) and particulate nitrogen (PN) concentrations in the Humber Estuary and tidal River Ouse Estuary. The POC data were derived from approximately monthly surveys and are consistent with data reported for suspended particulate matter (SPM) in the non-tidal River Ouse (the freshwater river) and with SPM, or bed sediments, in estuarine ecosystems such as the Mississippi, Delaware, San Francisco Bay, Tolo Harbour, the Vellar Estuary and Cochin Backwater, as well as the Loire, Gironde, Ems and Tamar Estuaries. Relative to the dry weight of SPM, the Humber-averaged organic carbon and nitrogen percentages during the year February 1995-March 1996 were 2.6 +/- 0.6% (mean and S.D.) and 0.21 +/- 0.04%, respectively. The ratio of Humber-averaged POC to Humber-averaged PN was 13 +/- 3. Higher POC levels were observed near the Humber's mouth and in the adjacent coastal zone during 'bloom' conditions, and in the upper estuarine reaches during large, winter and springtime freshwater inflows. At these times of high runoff, the POC content of SPM increased progressively up-estuary from the coastal zone to the tidal River Ouse. When inflows became very low, during late spring to early autumn of 1995, both the freshwater-saltwater interface (FSI) and the strengthening turbidity maximum (TM) moved further up-estuary and the POC content of SPM in the upper reaches of the Ouse became lower compared with that immediately down-estuary. This led to a poorly defined POC maximum near the confluence of the Humber, Ouse and Trent, before POC eventually decreased again towards the coastal zone. The lower POC contents in the upper estuarine reaches of the tidal Ouse may have been partly due to POC respiration by heterotrophic bacteria attached to SPM within the TM, consistent with the severe oxygen depletion observed there during high turbidity, summertime spring tides.

Is cognitive behavior therapy just a 'nonspecific' intervention for depression? A retrospective comparison of consecutive cohorts treated with cognitive behavior therapy or supportive counseling and pill placebo.

BACKGROUND: There is a dearth of placebo-controlled studies of cognitive behavior therapy (CBT) of depression and the largest such study, by Elkin et al. (Arch. Gen. Psychiatry 46 (1989) 971-982), failed to find a significant difference between CBT and a clinical management plus placebo condition. METHODS: The outcomes of two consecutive cohorts of out-patients with major depressive disorder, treated with either CBT (n=90) or a nonspecific control condition (support-counseling-placebo; SCP: n=100), were compared. Although the principal comparisons between the CBT and SCP conditions were delimited to the first 4 weeks of treatment, a secondary set of analyses addressed the subset of 16 patients who received 12 additional weeks of supportive therapy. RESULTS: A consistent pattern of statistically and clinically significant differences favoring CBT over SCP was found in both weeks 4 and 16. LIMITATIONS: Interpretation of these findings are subject to several potential confounds, including the non-randomized nature of the groups and the greater amount of therapeutic contact during the first 4 weeks of CBT. CONCLUSIONS: While these results do not lessen the need for additional prospective studies, our findings do suggest that CBT has therapeutic effects beyond those attributable to placebo-expectancy and other nonspecific factors.

Early- versus late-onset dythymic disorder: comparison in out-patients with superimposed major depressive episodes.

BACKGROUND: This study examined the validity of the early-late onset subtyping distinction in dysthymic disorder. METHODS: Participants were 340 out-patients meeting DSM-III-R criteria for dysthymia and a concurrent major depressive episode (MDE). The sample was drawn from a 12-site double-blind randomized parallel group trial comparing the efficacy of sertraline and imipramine in the treatment of chronic depression. All patients received comprehensive evaluations using semi-structured interviews and rating scales. RESULTS: 73% of the sample met criteria for the early-onset, and 27% for the late-onset, subtype. The early-onset patients had a significantly longer index MDE, significantly higher rates of personality disorders and lifetime substance use disorders, and a significantly greater proportion had a family history of mood disorder. The subgroups did not differ in symptom severity or functional impairment at baseline, nor in response to a 12-week trial of antidepressants. LIMITATIONS: Further work is needed to extend these findings to dysthymic disorder without superimposed MDEs. CONCLUSIONS: These results support the distinction between early-onset and late-onset dysthymic disorder.

Dysthymia: clinical picture, extent of overlap with chronic fatigue syndrome, neuropharmacological considerations, and new therapeutic vistas.

Dysthymia, as defined in the American Psychiatric Association and International Classification of Mental Disorders, refers to a prevalent form of subthreshold depressive pathology with gloominess, anhedonia, low drive and energy, low self-esteem and pessimistic outlook. Although comorbidity with panic, social phobic, and alcohol use disorders has been described, the most significant association is with major depressive episodes. Family history is loaded with affective, including bipolar, disorders. The latter finding explains why dysthymia, especially when onset is in childhood, can lead to hypomanic switches, both spontaneously and upon pharmacologic challenge in as many as 30%. Indeed, antidepressants from different classes -tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), reversible inhibitors of monoamine oxidase A (RIMAs), selective serotonin-reuptake inhibitors (SSRIs) and, more recently, amisulpride, and spanning noradrenergic, serotonergic as well as dopaminergic mechanisms of action - have been shown to be effective against dysthymia in an average of 65% of cases. This is a promising development because social and characterologic disturbances so pervasive in dysthymia often, though not always, recede with continued pharmacotherapy beyond acute treatment. Despite symptomatic overlap of dysthymia with chronic fatigue syndrome - especially with respect to the cluster of symptoms consisting of low drive, lethargy, lassitude and poor concentration - neither the psychopathologic status, nor the pharmacologic response profile of the latter syndrome is presently understood. Chronic fatigue today is where dysthymia was two decades ago. We submit that the basic science - clinical paradigm that has proven so successful in dysthymia could, before too long, crack down the conundrum of chronic fatigue as well. At a more practical level, we raise the possibility that a subgroup within the chronic fatigue group represents a variant of dysthymia.

Age of onset in chronic major depression: relation to demographic and clinical variables, family history, and treatment response.

BACKGROUND: The clinical and etiological significance of the early-late onset distinction in chronic major depressive disorder was explored. METHOD: Subjects were 289 outpatients with DSM-III-R chronic major depression drawn from a multi-site study comparing the efficacy of sertraline and imipramine in the acute and long-term treatment of chronic depression. Patients received comprehensive evaluations using semi-structured interviews and rating scales. RESULTS: Early-onset chronic major depression was associated with a longer index major depressive episode and higher rates of recurrent major depressive episodes, comorbid personality disorders, lifetime substance use disorders, depressive personality traits, and a history of psychiatric hospitalization. In addition, more early-onset patients tended to have a family history of mood disorders. The early-late onset distinction was not associated with differences in symptom severity, functional impairment, or treatment response. LIMITATIONS: Family members were not interviewed directly; there were a large number of statistical comparisons; and interrater reliability of the assessments was not evaluated. CONCLUSIONS: Early-onset chronic major depression has a more malignant course and is associated with greater comorbidity than late-onset chronic major depression.

Workplace performance effects from chronic depression and its treatment.

Utilizing data from a clinical trial and an econometric model incorporating the impact of a medical intervention and regression to the mean, we present evidence supporting the hypotheses that for chronically depressed individuals: (i) the level of perceived at-work performance is negatively related to the severity of depressive status; and (ii) a reduction in depressive severity improves the patient's perceived work performance. Improvement in work performance is rapid, with about two-thirds of the change occurring already by week 4. Those patients having the greatest work improvement are those with both relatively low baseline work performance and the least severity of baseline depression.

Treating antidepressant nonresponders with augmentation strategies: an overview.

This paper provides an overview of antidepressant nonresponse and the role of augmentation strategies in the management of treatment-resistant depression. When effective, the more widely used augmentation strategies, including lithium salts, thyroid hormones, pindolol, buspirone, and psychostimulants, share two important advantages when compared with "switching" strategies: avoidance of ill effects associated with discontinuing the initial antidepressant and rapidity of onset of action. Ideally, advances in the understanding of the neurobiology of mood disorders and mechanisms of antidepressant response will permit a more efficient and specific matching between patient, initial antidepressant, and subsequent strategy for enhancing response to treatment.

Predictors of response to acute treatment of chronic and double depression with sertraline or imipramine.

BACKGROUND: The literature on predictors of response to treatment of nonchronic major depression has identified shorter duration of illness, acute onset, and less severity of illness as positive predictors. Unfortunately, there are almost no data on predictors of response to treatment for chronic depression. This study examined predictors of response to pharmacotherapy (sertraline or imipramine) in the treatment of outpatients who had DSM-III-R-defined chronic major or double depression. METHOD: The acute phase of the Chronic Major Depression and Double Depression Study is a double-blind, randomized, parallel-group 12-week comparison of sertraline and imipramine. Analyses are based on 623 patients who comprised the intent-to-treat sample, of whom 299 were nonresponders and 324 were responders, defined by a priori criteria as either remission or satisfactory therapeutic response. A stepwise logistic multiple regression analysis was performed on candidate clinical, psychosocial, and demographic variables previously identified as statistically significant in an attempt to develop a predictive model of positive antidepressant response. RESULTS: The sociodemographic variables that were predictive of positive response included living with spouse or partner or being at least a high school graduate. With regard to symptomatology and clinical history, responders had significantly lower baseline depression severity scores. In general, comorbid anxiety, substance abuse, and personality disorders did not influence rates of response. However, the presence of depressive personality traits was associated with a higher nonresponse rate. Among psychosocial variables, longer duration of personal relationships as well as higher baseline quality of life were associated with positive response. A stepwise logistic multiple regression identified 5 variables-living with spouse or partner, higher educational level, passive-aggressive personality, lower introverted-tense personality traits, and higher quality of life--that significantly and independently contributed to the predictive model. This model correctly classified 67% of patients. CONCLUSION: A higher baseline quality of life, living with spouse or partner, and having more education were the strongest predictors of response to acute pharmacotherapy among chronically depressed patients. Clinical variables and comorbidity were not identified as independent predictors, although personality traits did appear to influence treatment response. Overall, the predictive value of these baseline measures was modest, and therefore of limited clinical utility.

A prospective test of criteria for response, remission, relapse, recovery, and recurrence in depressed patients treated with cognitive behavior therapy.

The definitions that are commonly employed to describe the outcome of the depressive disorders are often used in inconsistent ways and remain largely untested. The lack of a standard and valid set of outcome definitions hinders the study of the naturalistic course and treatment of depressive disorders. In the present study, we operationalized definitions for response, remission, relapse, recovery, and recurrence and examined their validity in a sample of depressed patients treated with cognitive behavior therapy. Validity was evaluated by the ability of the definitions to predict subsequent outcome in acute treatment and during a 3 year follow-up period. All five definitions demonstrated moderate to excellent validity. Moreover, we were able to empirically distinguish response from remission, and relapse from recurrence, despite the frequent confusion of these terms in the literature. Several of the findings suggest that continued refinement of the outcome definitions may enhance validity even further.

Pharmacotherapy of inpatients with bipolar depression.

The pharmacotherapy of bipolar depression has not been well studied. Controlled studies support the efficacy of some antimanic and antidepressant drugs, but these studies usually exclude patients typically seen in nonresearch settings. The purpose of this study was to examine the pharmacotherapy of 69 inpatients with bipolar depression. More than 90% of the patients received at least one antimanic drug, and lithium was used most frequently. Only one-half of the patients received antidepressants. Three-quarters of antidepressant-treated patients received serotonin reuptake inhibitors or other nontricyclic drugs. There were few differences between antidepressant- and non-antidepressant-treated patients. Psychotic patients were more likely to receive lithium, neuroleptics, and anticholinergics, whereas nonpsychotic patients tended to receive anticonvulsants more often. Psychotic patients were also more likely to receive polypharmacy. These results suggest that polypharmacy of inpatients with bipolar depression is common, and that psychosis is an important variable in the choice of pharmacotherapy.