Methane release from the southern Brazilian margin during the last glacial.

Seafloor methane release can significantly affect the global carbon cycle and climate. Appreciable quantities of methane are stored in continental margin sediments as shallow gas and hydrate deposits, and changes in pressure, temperature and/or bottom-currents can liberate significant amounts of this greenhouse gas. Understanding the spatial and temporal dynamics of marine methane deposits and their relationships to environmental change are critical for assessing past and future carbon cycle and climate change. Here we present foraminiferal stable carbon isotope and sediment mineralogy records suggesting for the first time that seafloor methane release occurred along the southern Brazilian margin during the last glacial period (40-20 cal ka BP). Our results show that shallow gas deposits on the southern Brazilian margin responded to glacial-interglacial paleoceanographic changes releasing methane due to the synergy of sea level lowstand, warmer bottom waters and vigorous bottom currents during the last glacial period. High sea level during the Holocene resulted in an upslope shift of the Brazil Current, cooling the bottom waters and reducing bottom current strength, reducing methane emissions from the southern Brazilian margin.

Learning styles and perceptions of the value of various learning modalities before and after a 2nd-year course in microbiology and infectious diseases.

BACKGROUND: The authors' 4-week course in microbiology and infectious diseases consists of lectures, small-group sessions, interactive computer-assisted learning (CAL), and textbook readings. PURPOSE: To determine how individual learning style influenced learners' value assessment of these teaching modalities. METHODS: A Kolb Learning Style Inventory and questionnaire to assess enthusiasm for each teaching modality were administered before the course. At course end, a 2nd questionnaire assessed the perceived usefulness of each teaching modality. RESULTS: Learners with a relative preference for experiential learning rather than abstraction initially favored small groups (R2 = .06, p = .004) and CAL (R2 = .06, p = .005). Similarly, learners with a preference for reflective observation rather than active experimentation favored lectures (R2 = .05, p = .01). However, at course end, Kolb learning style did not predict the value assessment of any modality. CONCLUSIONS: Kolb learning style influenced the initial attractiveness but not the retrospective assessment of learning modalities; hence, quality and content superseded learning style as determinants of value after course completion.

Model of family medicine and obstetrics-gynecology collaboration in obstetric care at the University of Michigan.

OBJECTIVE: To assess concordance between family physician obstetric privilege delineation and actual care delivered, and describe associated clinical and educational collaborations between family medicine and obstetrics and gynecology. METHODS: We conducted a descriptive retrospective review of the care and complications of 962 consecutive patients admitted to a family medicine obstetric service in a research-intensive academic medical center, and compared the results with a structured obstetric privilege delineation. RESULTS: Of 962 women admitted by family medicine faculty members, 741 (77.9%) were managed exclusively by family physicians, 63 (6.6%) were comanaged by family physicians and obstetricians, and 147 (15.5%) were transferred to obstetricians (data missing for 11 patients). Spontaneous vaginal deliveries were performed in 772 patients (81%), cesarean delivery in 116 patients (12.2%), and assisted delivery by forceps or vacuum in 19 (2%) and 44 (4.6%) patients, respectively. Of 926 intrapartum obstetric complications identified in 604 obstetric deliveries, 615 complications (66.4%) in 418 deliveries were managed exclusively by family physicians consistent with privilege delineation, comanagement occurred in 56 patients with 92 complications (9.9%), and care was transferred in 130 patients with 219 complications (23. 7%). CONCLUSION: A structured method of obstetric privilege delineation for family medicine faculty members and associated guidelines for family physician-obstetrician interactions has led to a successful family medicine obstetric service at a research-intensive, tertiary-care medical center, with a high concordance between privilege delineation and actual care delivered. This success has resulted in incremental clinical and educational collaborations that have improved the quality of women's health care and education.

Physical activity and mental health: current concepts.

Physical activity may play an important role in the management of mild-to-moderate mental health diseases, especially depression and anxiety. Although people with depression tend to be less physically active than non-depressed individuals, increased aerobic exercise or strength training has been shown to reduce depressive symptoms significantly. However, habitual physical activity has not been shown to prevent the onset of depression. Anxiety symptoms and panic disorder also improve with regular exercise, and beneficial effects appear to equal meditation or relaxation. In general, acute anxiety responds better to exercise than chronic anxiety. Studies of older adults and adolescents with depression or anxiety have been limited, but physical activity appears beneficial to these populations as well. Excessive physical activity may lead to overtraining and generate psychological symptoms that mimic depression. Several differing psychological and physiological mechanisms have been proposed to explain the effect of physical activity on mental health disorders. Well controlled studies are needed to clarify the mental health benefits of exercise among various populations and to address directly processes underlying the benefits of exercise on mental health.

Alcohol use in adolescents: the scope of the problem and strategies for intervention.

Alcohol use among adolescent athletes is fairly high, but the problem is complex. Young athletes may be more likely to abuse alcohol than their nonathlete peers and more likely to suffer behavioral and psychosocial consequences as a result of drinking. They are also more prone to binge drinking. Education and prevention strategies should focus on behavioral and psychosocial consequences because athletic performance typically does not suffer. A change in behavior is most likely to alert a physician to an alcohol problem, which is best addressed using a direct approach.

Rejuvenating patients-one step at a time.

We are watching a vast natural experiment: Take millions of Americans off farms, off manual labor. Give them desk jobs, cars, and televisions. Add sanitation and antibiotics to increase life span. Then sit back and watch what-and how-the people do. You know the results from epidemiologic studies and from your own practice: The average American lives a long time, but he or she is sedentary, fat, unfit-and, often, chronically ill. The worst impact is on the older adults who have accumulated a lifetime of this comfortable but ultimately disabling lifestyle.

False positives, false negatives, and the validity of the diagnosis of major depression in primary care.

OBJECTIVE: To explore the issues of diagnostic specificity and psychiatric "caseness" (i.e., whether a patient meets the conditions to qualify as a "case" of a disease or syndrome) for major depression in the primary care setting. DESIGN: A cross-sectional study comparing the demographic, clinical, and mental health characteristics of patients identified as depressed by their family physicians with those meeting diagnostic criteria for major depression on the criterion standard Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition. SETTING: The offices of 50 family physicians from private and academic practice in southeast Michigan. PATIENTS: A total of 1580 consecutive adult patients being seen for routine primary care services, from whom a weighted sample of 372 patients completed a set of mental health screening and diagnostic instruments. MAIN OUTCOME MEASURES: Patients were assigned to 1 of 4 groups (true positive, false positive, false negative, and true negative) based on clinician identification and Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition diagnosis. Differences between the 4 groups in demographic and clinical characteristics, scores on mental health instruments and mental health history were explored. RESULTS: Physician identification of depression was strongly associated with increased familiarity with the patient and the presence of suggestive clinical cues, such as history of or treatment for depression, patient distress, and presence of vegetative symptoms. Patients in the false-positive group displayed significantly higher levels of distress and impairment and were significantly more likely to have a history of mental health problems and treatment than were those in the true-negative group. The 2 "misidentified" groups, false positives and false negatives, were indistinguishable in their clinical characteristics (impairment, distress, or mental health history). Both groups' scores occupied the middle ground between true positives and true negatives on most clinical characteristics. Physicians appeared to discriminate between these 2 groups on the basis of their knowledge of the patient's clinical history. CONCLUSIONS: Misidentification of depression in primary care may be in part an artifact of the use of the psychiatric model of caseness in the primary care setting. Our results are most consistent with a chronic disease-based model of depressive disorder, in which patients classified as false positive and false negative occupy a clinical middle ground between clearly depressed and clearly nondepressed patients. Family physicians appear to respond to meaningful clinical cues in assigning the diagnosis of depression to these distressed and impaired patients.

Cancer and depression.

There is strong evidence that depression can have profound negative effects on the functional status, psychologic outlook, and possibly the medical outcome of cancer patients. Its presence often is taken for granted by both patients and physicians as being either inevitable or easily explained by the grim prognosis and complex treatment regimens experienced by many cancer patients, and thereby less deserving of an aggressive approach to diagnosis and treatment. This view is inappropriate, and hinders an effective approach to the problem. Effective treatment, similar to that provided for any other depressed patient, can enhance the cancer patient's overall approach to life and the disease, irrespective of the eventual medical outcome.

The nature and prevalence of anxiety disorders in primary care.

Primary goals of this study were to 1) establish the prevalence, nature, and correlates of anxiety disorders in primary care, and 2) examine the comorbidity of anxiety disorders with major depressive disorder. A weighted sample of 425 patients drawn from the waiting rooms of primary care physicians was used. Anxiety disorders were highly prevalent, relatively mild, and often comorbid with depression. Anxiety disorders aided physicians in their detection of depression. However, anxiety disorders were also misdiagnosed as depression. Although anxiety disorders are common in primary care, their relative mildness may generally not warrant increased attention by primary care physicians to detection and treatment. Instead, efforts should be focused on the more severe and impairing cases of anxiety disorder.

Depression in the family physician's office: what the psychiatrist needs to know: the Michigan Depression Project.

A rapidly growing body of research suggests that depression in primary care may differ from that in psychiatry in its nature, severity, comorbidity, and responsiveness to treatment. The Michigan Depression Project is a long-term series of studies designed to explore the twin assumptions that depressed primary care patients are similar to depressed psychiatric patients and that identical treatment will benefit both groups. Major findings are (1) criterion-based diagnosis of major depressive disorder in primary care includes many patients with mild depression and little to no impairment; (2) the onset of depression among family practice patients-but not psychiatric patients-is usually preceded by a severe life event; (3) in primary care, outcome for patients with undetected depression appears to be comparable to that for those with detected depression; and (4) family physicians appear to employ historical cues in assigning the diagnosis of depression to distressed and impaired patients. The results of the Michigan Depression Project and the recent work of other researchers suggest that the challenges facing primary care physicians in the diagnosis and treatment of depressed patients are daunting. These challenges lead to a set of consultative skills and behaviors on the part of psychiatrists that may be different than generally expected. One-time, stand-alone psychiatric consultations are often needed, because neither the primary care physician nor the patient desires the psychiatric care to be "carved out" from the continuing care of a set of chronic problems. Future intervention studies should compare subgroups of patients who appear most in need of treatment (on the basis of functional impact) with those who are mildly depressed and barely meet diagnostic criteria. These studies will help primary care physicians focus their energies and therapies where they will have the most benefit in treating what is clearly a common and important, but still poorly understood, problem in primary care medical practice.

Can case-finding instruments be used to improve physician detection of depression in primary care?

OBJECTIVE: To explore the issue of diagnostic specificity for major depression in the primary care setting by examining the relative accuracy of 3 methods to detect major depression in primary care. DESIGN: Comparison of performance characteristics of 3 case-finding methods for depression (ie, the Center for Epidemiologic Studies-Depression scale [CES-D], unaided physician detection, and "augmented" physician detection by use of a case-finding instrument), with the standard criterion being the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM-III-R). SETTING: The offices of 50 family physicians from private and academic practice in southeastern Michigan. PATIENTS: Adult patients (N = 1580) who presented for routine care, from which a weighted random sample of 425 patients completed the Structured Clinical Interview for DSM-III-R. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value, and positive likelihood ratio for each case-finding method. RESULTS: Major depression was present in 13.4% of the sample. Both the CES-D and unaided physician detection methods performed poorly in identifying patients who met DSM-III-R criteria for major depressive disorder. The CES-D had high sensitivity but low specificity at standard and high cut points, resulting, respectively, in low positive predictive values (0.307 and 0.385) and low positive likelihood ratios (2.9 and 4.0). Unaided physician detection showed lower sensitivity, higher specificity, and a slightly higher positive predictive value (0.45) and positive likelihood ratio (4.9). Raising of the CES-D threshold for a positive test did not enhance the detection of depression. Augmented physician detection with CES-D scores resulted in minimal improvement. Although the positive predictive value and positive likelihood ratio increased to 0.50 and 6.1, respectively, using the most stringent case-finding definition (ie, physician identification plus the CES-D score [score > or = 22]), the proportion of depressed patients who were correctly identified decreased to 26.9%. CONCLUSIONS: Neither high scores on the CES-D nor unaided physician detection accurately identified patients with major depression who were seen in primary care settings, while the supplementation of physician detection with CES-D scores had a minimal net effect on the accuracy of detection. The data do not support the routine use of the CES-D as a primary care screening instrument for depression, either as a stand-alone measure or as a supplement to physician detection.

Short-term outcomes of detected and undetected depressed primary care patients and depressed psychiatric patients.

The aims of this study were to determine whether detection of major depression in primary care was associated with improved outcome, and to compare the 4.5 month outcomes of detected and undetected depressed primary care patients and depressed psychiatric patients. Primary care patients with major depression were recruited from the practices of 50 family physicians in Southeastern Michigan using a two-stage selection procedure employing the Center for Epidemiologic Studies-Depression Scale (CES-D) and the Structured Clinical Interview for DSM-III-R (SCID); clinician detection of depression was ascertained by response to a direct query on a rating form. Depressed patients seeking treatment in an outpatient psychiatric setting also received the CES-D and the SCID. Data on patient demographics and clinical characteristics were obtained for both primary care and psychiatric patients. Initial and 4.5 month scores on the Hamilton Depression Rating Scale (HAM-D) were obtained for 34 undetected and 25 detected depressed primary care and 55 depressed psychiatric patients. Improvement in depression over time was assessed by the change in HAM-D scores over the 4.5 months. The three groups did not differ in initial severity. Both psychiatric and undetected primary care patients showed significant improvement at 4.5 months, whereas detected primary care patients did not improve. At 4.5 months there were no differences in mean HAM-D scores between undetected, depressed primary care patients and depressed psychiatric outpatients. This result did not change after controlling for age and severity of depression at initial presentation, nor did it change after exclusion of cases of mild depression to control for a possible "floor effect." However, differences among groups in the stage of depressive episodes may have affected this comparison. These findings suggest that an exclusive focus on increasing detection of depression in primary care patients is unlikely to improve outcomes, and that undetected depression among primary care patients does not necessarily represent poor quality of care. Although depressed psychiatric patients in this study had better outcomes than detected depressed primary care patients, the presence of unmeasured differences among groups in the stage of the depressive episode makes it impossible to determine whether treatment of depression by psychiatrists is superior to that provided by primary care physicians. These findings should stimulate efforts to examine a more comprehensive model for detection and treatment of depression in primary care.

Accuracy of the conductance catheter for measurement of ventricular volumes seen clinically: effects of electric field homogeneity and parallel conductance.

The conductance-volume method is an important clinical tool which allows the assessment of left ventricular function in vivo. However, the accuracy of this method is limited by the homogeneity of electric field the conductance catheter produces and the parallel conductance of surrounding structures. This paper examines these sources of error in volumes seen clinically. The characteristics of electric field within a chamber were examined using computer simulation. Nonconductive and conductive models were constructed and experimental measurements obtained using both single-field (SF) and dual-field (DF) excitation. Results from computer simulations and in vitro measurements were compared to validate the purposed theoretical model of conductance-volume method. The effects of field homogeneity and significance of parallel conductance in volume measurement were then determined. The results of this study show that DF provide a more accurate measure of intraventricular volume than SF, especially at larger volumes. However, both significantly underestimate true volume at larger volumes. In addition, the parallel conductance due to the chamber wall is significant at small volumes, but diminishes at larger volumes. Furthermore, the effect of parallel conductance beyond the chamber wall may be negligible. This study demonstrates the limitations in applying current conductance technology to patients with dilated hearts.

The relationship of distress to mood disturbance in primary care and psychiatric populations.

Disagreement remains as how to interpret elevated scores on measures of self-reported distress. This study compared elevated scores on the Center for Epidemiologic Studies-Depression Scale (CES-D) in 2 samples to mood disturbance as assessed in an interview. In a primary medical care sample, most distressed patients did not have a mood disturbance, and distress without mood disturbance was associated with little impairment. Primary care patients with elevated scores on the CES-D were less distressed and less likely to have mood disturbance, major depression, or impairment than distressed psychiatric patients. Few patients with mood disturbance in either sample failed to meet criteria for major depression. Implications are discussed for research on depression using self-report measures, for generalizations across clinical and nonclinical populations, and for screening for preventive interventions.