Large seasonal swings in leaf area of Amazon rainforests

Despite early speculation to the contrary, all tropical forests studied to date display seasonal variations in the presence of new leaves, flowers, and fruits. Past studies were focused on the timing of phenological events and their cues but not on the accompanying changes in leaf area that regulate vegetation-atmosphere exchanges of energy, momentum, and mass. Here we report, from analysis of 5 years of recent satellite data, seasonal swings in green leaf area of approximately 25% in a majority of the Amazon rainforests. This seasonal cycle is timed to the seasonality of solar radiation in a manner that is suggestive of anticipatory and opportunistic patterns of net leaf flushing during the early to mid part of the light-rich dry season and net leaf abscission during the cloudy wet season. These seasonal swings in leaf area may be critical to initiation of the transition from dry to wet season, seasonal carbon balance between photosynthetic gains and respiratory losses, and litterfall nutrient cycling in moist tropical forests.     

Five year outcomes study of dental rehabilitation conducted under general anesthesia for special needs patients

We assessed the safety of general anesthesia for dental treatment of special needs patients as it related to American Society of Anesthesiology Physical Status (ASAPS) classification, procedure, and other factors. After Institutional Review Board review and approval, special needs patients who were admitted to the outpatient surgical operating room for comprehensive dental rehabilitation (CDR) under general anesthesia within a period of 5 years had their medical records evaluated retrospectively for intraoperative and postoperative complications both related to anesthesia and surgery. All records were evaluated by an independent evaluator who tabulated the patients' age, gender, ASAPS, and duration of procedure. N = 363, age mean = 46.93 +/- 16.835 years, age median = 48 years, male patients = 180, female patients = 183, ASAPS I =183, ASAPS II = 127, ASAPS III = 53, duration of surgery mean = 140.631 +/- 23.104 minutes, duration of surgery median time = 142.000 minutes, and number of complications = 2. One complication resulted in an ASAPS I 16-year-old boy, which was airway related, and a second was an ASAPS III 22-year-old woman, which was surgically related. Both led to unplanned inpatient admissions and were treated successfully with no residual morbidity. Dental rehabilitation of special needs patients under general anesthesia is safe. While morbidity is very low, larger studies are needed to establish risk versus benefit stratification among this patient population.     

Eccentric target sign in cerebral toxoplasmosis: Neuropathological correlate to the imaging feature

Cerebral toxoplasmosis remains one of the most common focal brain lesions in patients with acquired immune deficiency syndrome (AIDS). Diagnosis is a challenge because on cranial imaging it closely mimics central nervous system lymphoma, primary and metastatic central nervous system (CNS) tumors, or other intracranial infections like tuberculoma or abscesses. A magnetic resonance imaging (MRI) feature on postcontrast T1‐weighted sequences considered pathognomonic of toxoplasmosis is the “eccentric target sign.” The pathological correlate of this imaging sign has been speculative. Herein we correlate the underlying histopathology to the MR feature of eccentric target sign in a patient with autopsy‐proven HIV/AIDS‐related cerebral toxoplasmosis. The central enhancing core of the target seen on MRI was produced by a leash of inflamed vessels extending down the length of the sulcus that was surrounded by concentric zones of necrosis and a wall composed of histiocytes and proliferating blood vessels, with impaired permeability producing the peripheral enhancing rim. J. Magn. Reson. Imaging 2010;31:1469–1472. © 2010 Wiley‐Liss, Inc.     

Effect of gossypol on the fertility of male rats.

Thirty male rats were grouped into 5 groups of 6 animals each. Animals in groups II-V were given gossypol at a dose of 5 mg/kg, 10 mg/kg, 20 mg/kg and 40 mg/kg body weight per day for 45 days respectively. Animals of group I served as control. A significant decrease in body weight after administration of 40 mg/kg body weight of gossypol was observed; low doses of gossypol, however did not affect the body weight. Testis, epididymis, prostate and seminal vesicles weights decreased gradually with the increasing doses of gossypol. With the increasing doses of gossypol, a marked decrease in the vas deferens sperm motility was observed. At 40 mg/kg dose there was a total inhibition of sperm motility. Histological studies after 5 mg/kg revealed no apparent sign of degeneration, while after 10 mg/kg dose the changes in the individual cell types were accompanied by overall disorganisation of the germinal epithelium involving displacement of the spermatocytes. The rats treated with 20-40 mg/kg gossypol showed a pronounced deleterious effect on the histological structure of the testis. The drug effect was dose dependent developing sequentially; from the uppermost layer of elongated spermatids affecting round spermatids and finally spermatocytes. Quantitatively the ratios of pachytene spermatocytes: resting spermatocytes, stage 7 spermatids: pachytene spermatocytes, and stage 19 spermatids: stage 7 spermatids and tubular diameter and germinal height decreased significantly. The activities of glucose-6-phosphatase, fructose 1, 6-diphosphatase, glucose-6-phosphate isomerase in testis decreased significantly at high dose (40 mg/kg), while the activity of amylase and glycogen content increased significantly with the increasing doses of gossypol.(ABSTRACT TRUNCATED AT 250 WORDS)     

Greater MRI lesion volumes in elderly depressed subjects than in control subjects

Hyperintense lesions in both white matter and gray matter on T2-weighted magnetic resonance imaging (MRI) are associated with late-life depression. This large study examined differences in gray and white matter lesion volumes on brain MRI between 253 elderly depressed and 146 control subjects. White matter and gray matter lesion volumes were measured in each hemisphere using a semi-automated segmentation process and compared against depression status. Depressed subjects exhibited significantly greater total white matter (mean 7.22 ml) and gray matter (mean 0.30 ml) lesion volumes in both hemispheres than did control subjects (mean 4.87 ml in white matter and 0.18 ml in gray matter). This difference remained statistically significant even after controlling for confounders such as age, sex, race and reports of hypertension, diabetes and heart disease. Patients with late-life depression have larger white matter lesion and gray matter lesion volumes than do control subjects. Future research should combine similar volumetric techniques with methods of identifying the location of lesions specific to late-life depression.     

Relationship between release of platelet/endothelial biomarkers and plasma levels of sertraline and N-desmethylsertraline in acute coronary syndrome patients receiving SSRI treatment for depression

OBJECTIVE: In a platelet/endothelial biomarker substudy of the Sertraline AntiDepressant Heart Attack Randomized Trial (SADHART), the authors sought to determine whether plasma levels of sertraline and its primary metabolite N-desmethylsertraline affect the release of platelet/endothelial biomarkers. METHOD: Fifty-five acute coronary syndrome patients with depression were randomly assigned to receive sertraline (N=23) or placebo (N=32). Twenty-six serial plasma samples collected at week 6 (N=12) and week 16 (N=14) were analyzed. Platelet factor 4 (PF4), beta-thromboglobulin (beta-TG), platelet/endothelial cell adhesion molecule 1 (PECAM-1), P-selectin, thromboxane B(2) (TxB(2)), prostacyclin (6-keto-PGF1alpha), vascular cell adhesion molecule 1 (VCAM-1), and E-selectin were measured by enzyme-linked immunosorbent assay. Concentrations of sertraline and N-desmethylsertraline were determined by liquid chromatography with fluorescence detection in autologous samples. RESULTS: Strong, mostly time-dependent negative correlations were found for the plasma levels of sertraline and N-desmethylsertraline with PF4 (week 6: r=-0.69 and -0.33, respectively; week 16: r=-0.63 for both), beta-TG (week 6: r=-0.43 and -0.29; week 16: r=-0.66 and -0.57), PECAM-1 (week 6: r=-0.82 and -0.49; week 16: r=-0.60 for both), P-selectin (week 6: r=-0.82 and -0.49; week 16: r=-0.73 and -0.43), and TxB(2) (week 6: r=-0.66 and -0.59; and week 16: r=-0.64 and -0.41). Regression analysis revealed some borderline correlations for endothelial markers such as 6-keto- PGF1alpha and E-selectin and a positive correlation for VCAM-1. CONCLUSIONS: This is the first documented evidence that plasma release of platelet/endothelial biomarkers is directly related to the levels of sertraline and N-desmethylsertraline in acute coronary syndrome patients receiving SSRI treatment for depression. The clinical significance of these findings should be assessed in the setting of a randomized clinical trial.     

Effects of antidepressant medication on morbidity and mortality in depressed patients after myocardial infarction

BACKGROUND: Depression after myocardial infarction (MI) is associated with higher morbidity and mortality. Although antidepressants are effective in reducing depression, their use in patients with cardiovascular disease remains controversial. OBJECTIVE: To undertake a secondary analysis to determine the effects of using antidepressants on morbidity and mortality in post-MI patients who participated in the Enhancing Recovery in Coronary Heart Disease study. DESIGN: Observational secondary analysis. SETTING: Eight academic sites. PATIENTS: The Enhancing Recovery in Coronary Heart Disease clinical trial randomized 2481 depressed and/or socially isolated patients from October 1, 1996, to October 31, 1999. Depression was diagnosed using a structured clinical interview. This analysis was conducted on the 1834 patients enrolled with depression (849 women and 985 men). INTERVENTION: Use of antidepressant medication. MAIN OUTCOME MEASURES: Event-free survival was defined as the absence of death or recurrent MI. All-cause mortality was also examined. To relate exposure to antidepressants to subsequent morbidity and mortality, the data were analyzed using a time-dependent covariate model. RESULTS: During a mean follow-up of 29 months, 457 fatal and nonfatal cardiovascular events occurred. The risk of death or recurrent MI was significantly lower in patients taking selective serotonin reuptake inhibitors (adjusted hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.38-0.84), as were the risk of all-cause mortality (adjusted HR, 0.59; 95% CI, 0.37-0.96) and recurrent MI (adjusted HR, 0.53; 95% CI, 0.32-0.90), compared with patients who did not use selective serotonin reuptake inhibitors. For patients taking non-selective serotonin reuptake inhibitor antidepressants, the comparable HRs (95% CIs) were 0.72 (0.44-1.18), 0.64 (0.34-1.22), and 0.73 (0.38-1.38) for risk of death or recurrent MI, all-cause mortality, or recurrent MI, respectively, compared with nonusers. CONCLUSIONS: Use of selective serotonin reuptake inhibitors in depressed patients who experience an acute MI might reduce subsequent cardiovascular morbidity and mortality. A controlled trial is needed to examine this important issue.     

Randomized, placebo-controlled trial of the effects of donepezil on neuronal markers and hippocampal volumes in Alzheimer's disease

OBJECTIVE: The authors examined the effect of the acetylcholinesterase inhibitor donepezil on magnetic resonance markers of neurodegeneration in Alzheimer's disease. METHOD: In this randomized, double-blind, placebo-controlled pilot study, 67 patients with mild to moderate Alzheimer's disease received 24 weeks of treatment with donepezil (5 mg/day for the first 28 days and 10 mg/day thereafter) or placebo. Patients were reevaluated at 6-week intervals to measure change from baseline in several outcome measures, including right, left, and total hippocampal volumes, measured with magnetic resonance imaging; brain concentrations of N-acetylaspartate, measured with proton magnetic resonance spectroscopy; and cognition, assessed with the Alzheimer's Disease Assessment Scale cognitive subscale. RESULTS: At some interim assessments, mean normalized measures of N-acetylaspartate concentration tended to be higher in the donepezil-treated patients than in the patients who received placebo, but these differences were not significant at endpoint. At endpoint, the donepezil-treated patients had significantly smaller mean decreases in total and right hippocampal volumes and a smaller, nearly significant mean decrease in left hippocampal volume, compared with the placebo-treated patients. Mean Alzheimer's Disease Assessment Scale cognitive subscale scores were improved after treatment with donepezil, relative to placebo, at weeks 6, 12, 18, and 24. CONCLUSIONS: These preliminary results suggest that donepezil may have a potentially protective effect in Alzheimer's disease. Larger, longer-term confirmatory studies of the medication's effects are warranted.