In vivo chemotactic properties and spatial expression of PDGF in developing mesenteric microvascular networks.

The recruitment of perivascular cells to developing microvessels is a key component of microvessel assembly. Whereas platelet-derived growth factor (PDGF) signaling is critical for this process during embryonic development, its role from the postnatal stages through adulthood remains unclear. We investigated the potential role of PDGF signaling during microvessel assembly by measuring in vivo the migration of labeled fibroblasts to PDGF in mesenteric connective tissue and by examining PDGF-B and PDGF receptor-beta (PGDFR-beta) expression in microvascular networks during normal maturation. PDGF-B homodimer (PDGF-BB; 30 ng/ml) application elicited a significant (P < 0.05) increase (7.8 +/- 4.1 cells) in labeled fibroblasts within 100 microm of the source micropipette after 2 h. PDGF-A homodimer (30 ng/ml) application and control solution did not elicit directed migration. PDGF-B was expressed in microvessel endothelium and smooth muscle, whereas PDGFR-beta was expressed in endothelium, smooth muscle, and interstitial fibroblasts. Given that PDGF-BB elicits fibroblast migration in the mesentery and that PDGF-B and PDGFR-beta are expressed in a pattern that indicates paracrine signaling from microvessels to the interstitium, the results are consistent with a role for PDGF-B in perivascular cell recruitment to microvessels.

Psychosocial disability during the long-term course of unipolar major depressive disorder.

BACKGROUND: The goal of this study was to investigate psychosocial disability in relation to depressive symptom severity during the long-term course of unipolar major depressive disorder (MDD). METHODS: Monthly ratings of impairment in major life functions and social relationships were obtained during an average of 10 years' systematic follow-up of 371 patients with unipolar MDD in the National Institute of Mental Health Collaborative Depression Study. Random regression models were used to examine variations in psychosocial functioning associated with 3 levels of depressive symptom severity and the asymptomatic status. RESULTS: A progressive gradient of psychosocial impairment was associated with a parallel gradient in the level of depressive symptom severity, which ranges from asymptomatic to subthreshold depressive symptoms to symptoms at the minor depression/dysthymia level to symptoms at the MDD level. Significant increases in disability occurred with each stepwise increment in depressive symptom severity. CONCLUSIONS: During the long-term course, disability is pervasive and chronic but disappears when patients become asymptomatic. Depressive symptoms at levels of subthreshold depressive symptoms, minor depression/ dysthymia, and MDD represent a continuum of depressive symptom severity in unipolar MDD, each level of which is associated with a significant stepwise increment in psychosocial disability.

Major depressive disorder: a prospective study of residual subthreshold depressive symptoms as predictor of rapid relapse.

BACKGROUND: The study tested whether level of recovery from major depressive episodes (MDEs) predicts duration of recovery in unipolar major depressive disorder (MDD) patients. METHODS: MDD patients seeking treatment at five academic centers were followed naturalistically for 10 years or longer. Patients were divided on the basis of intake MDE recovery into residual depressive symptoms (SSD; N=82) and asymptomatic (N=155) recovery groups. They were compared on time to first episode relapse/recurrence, antidepressant medication, and comorbid mental disorders. Recovery level was also compared to prior history of recurrent MDEs ( > 4 lifetime episodes) as a predictor of relapse/recurrence. RESULTS: Residual SSD compared to asymptomatic recovery patients relapsed to their next MDE > 3 times faster (median=68 vs. 23 weeks) and to any depressive episode > 5 times faster (median=33 vs. 184 weeks). Residual SSD recovery status was significantly associated with early episode relapse (OR=3.65) and was stronger than history of recurrent MDEs (OR=1.64). Rapid relapse in the SSD group could not be attributed to higher comorbidity or lower antidepressant treatment. LIMITATIONS: Although inter-rater agreement on weekly depressive symptom ratings was very high (ICC > 0.88), some error may exist in assigning recovery levels. Antidepressant treatments were recorded, but were not controlled. CONCLUSIONS: MDE recovery is a powerful predictor of time to episode relapse/recurrence. Residual SSD recovery is associated with very rapid episode relapse which supports the idea that SSD is an active state of illness. Asymptomatic recovery is associated with prolonged delay in episode recurrence. These findings of this present study have important implications for the goals of treatment of MDD and for defining true MDE recovery.

A prospective 12-year study of subsyndromal and syndromal depressive symptoms in unipolar major depressive disorders.

BACKGROUND: Investigations of unipolar major depressive disorder (MDD) have focused primarily on major depressive episode remission/recovery and relapse/recurrence. This is the first prospective, naturalistic, long-term study of the weekly symptomatic course of MDD. METHODS: The weekly depressive symptoms of 431 patients with MDD seeking treatment at 5 academic centers were divided into 4 levels of severity: (1) depressive symptoms at the threshold for MDD; (2) depressive symptoms at the threshold for minor depressive or dysthymic disorder (MinD); (3) subsyndromal or subthreshold depressive symptoms (SSDs), below the thresholds for MinD and MDD; and (4) no depressive symptoms. The percentage of weeks at each level, number of changes in symptom level, and medication status were analyzed overall and for 3 subgroups defined by mood disorder history. RESULTS: Patients were symptomatically ill in 59% of weeks. Symptom levels changed frequently (1.8/y), and 9 of 10 patients spent weeks at 3 or 4 different levels during follow-up. The MinD (27%) and SSD (17%) symptom levels were more common than the MDD (15%) symptom level. Patients with double depression and recurrent depression had more chronic symptoms than patients with their first lifetime major depressive episode (72% and 65%, respectively, vs 46% of follow-up weeks). CONCLUSION: The long-term weekly course of unipolar MDD is dominated by prolonged symptomatic chronicity. Combined MinD and SSD level symptoms were about 3 times more common (43%) than MDD level symptoms (15%). The symptomatic course is dynamic and changeable, and MDD, MinD, and SSD symptom levels commonly alternate over time in the same patients as a symptomatic continuum of illness activity of a single clinical disease.

Contribution of individual structural components in determining the zero-stress state in small arteries.

Arterial-wall stress distributions are important determinants of arterial function and are determined by the mechanical properties of the vessel wall, the physiological loading conditions, and the zero stress state of the artery. In this study, the relationship between this zero-stress state, the contractile state of the vessel, and the extracellular matrix components was investigated. Rat saphenous arteries were excised, and cross-sectional slices were cut. Wall thickness, intimal circumference, medial to adventitial border circumference, and the outer adventitial circumference were measured. Each slice was cut once longitudinally to relieve the residual stresses, and after a period of 30 min, vessel dimensions were again measured, and the angle to which the arterial section opened, a measure of the residual stress present in the intact artery, was recorded in this new zero-stress state. Control 'opening angle' was 112+/-10 degrees (mean+/-SD, n= 8) as compared to 138+/-6 degrees (n = 18) and 127+/-6 degrees (n = 11) for slices placed in 10(-4) M adenosine at 25 and 37 degrees C, respectively. Fluorescein isothiocyanate dextran was also injected intravenously in 8 animals to measure the homeostatic lumen diameter and wall thickness using intravital microscopy. Comparison of homeostatic strains calculated from these in situ dimensions to residual strains indicated that a given opening angle produced a radially uniform circumferential strain only for a specific level of tone. These results suggest that smooth muscle tone can acutely modify residual strain, possibly through interconnections with matrix components. Furthermore, selective elimination of matrix components by post-treatment of zero-stress slices with elastase or collagenase in 6 animals each increased the opening angle by 53 and 70%, respectively, suggesting that the extracellular matrix structure may regulate arterial strains in the long term.

Switching from 'unipolar' to bipolar II. An 11-year prospective study of clinical and temperamental predictors in 559 patients.

BACKGROUND: Given the therapeutic and prognostic importance of the unipolar-bipolar dichotomy, predicting which patients will become bipolar subsequent to index diagnosis of major depressive disorder (MDD) is of paramount clinical significance. We sought to characterize the profile of patients with MDD who would convert to the more subtle bipolar subtype (known as BPII) on the basis of clinical and personality variables obtained during MDD episodes. METHODS: A total of 559 patients, comprehensively evaluated with the Schedule of Affective Disorders and Schizophrenia and "unipolar" MDD at entry, were administered 17 self-report personality measures. Hypomanic and manic episodes were systematically recorded over a prospective observation period of up to 11 years. We compared 48 converters to BPII (8.6%) with 22 converters to bipolar I (BPI) (3.9%) and the remaining larger group of unipolar patients. RESULTS: Except for greater acuteness, severity, and psychotic symptomatology, BPI converters were essentially similar to MDD nonconverters. By contrast, BPII converters were robustly distinguished from those with MDD who remained unipolar on the basis of self-report measures along the newly derived factors of Mood Lability, Energy-Activity, and Daydreaming. This profile was associated with early age at onset of MDD and pleomorphic psychopathology beyond the usual affective realm, high rates of substance abuse, as well as educational, marital, and occupational disruption and minor antisocial acts prior to discrete hypomanic episodes. Overall, BPII switchers had a more protracted and tempestuous course with shorter well intervals. "Habitual self" descriptions of temperamental instability during MDD episodes provided useful clinical information for predicting which depressed patients will switch to BPII, attaining a sensitivity of 91% for all three factors combined (23 items); Mood Lability alone (nine items) was the most specific predictor (86%), though of lower sensitivity (42%). CONCLUSIONS: The BPII subtype is best understood by such lability intruding into, and possibly its accentuation during, depressive episodes, thereby creating an intimate interweaving of trait and state. Clinicians must note that the foregoing temperamental profile appears more fundamental in defining the affective dysregulation of the BPII subtype than hypomanic episodes emphasized in DSM-IV.