Near-Cloud Aerosol Retrieval Using Machine Learning Techniques, and Implied Direct Radiative Effects.

There is a lack of satellite-based aerosol retrievals in the vicinity of low-topped clouds, mainly because reflectance from aerosols is overwhelmed by three-dimensional cloud radiative effects. To account for cloud radiative effects on reflectance observations, we develop a Convolutional Neural Network and retrieve aerosol optical depth (AOD) with 100-500 m horizontal resolution for all cloud-free regions regardless of their distances to clouds. The retrieval uncertainty is 0.01 + 5%AOD, and the mean bias is approximately -2%. In an application to satellite observations, aerosol hygroscopic growth due to humidification near clouds enhances AOD by 100% in regions within 1 km of cloud edges. The humidification effect leads to an overall 55% increase in the clear-sky aerosol direct radiative effect. Although this increase is based on a case study, it highlights the importance of aerosol retrievals in near-cloud regions, and the need to incorporate the humidification effect in radiative forcing estimates.

Observational Constraints on Warm Cloud Microphysical Processes Using Machine Learning and Optimization Techniques.

We introduce new parameterizations for autoconversion and accretion rates that greatly improve representation of the growth processes of warm rain. The new parameterizations capitalize on machine-learning and optimization techniques and are constrained by in situ cloud probe measurements from the recent Atmospheric Radiation Measurement Program field campaign at Azores. The uncertainty in the new estimates of autoconversion and accretion rates is about 15% and 5%, respectively, outperforming existing parameterizations. Our results confirm that cloud and drizzle water content are the most important factors for determining accretion rates. However, for autoconversion, in addition to cloud water content and droplet number concentration, we discovered a key role of drizzle number concentration that is missing in current parameterizations. The robust relation between autoconversion rate and drizzle number concentration is surprising but real, and furthermore supported by theory. Thus, drizzle number concentration should be considered in parameterizations for improved representation of the autoconversion process.

Cost analysis of negative-pressure wound therapy with instillation for wound bed preparation preceding split-thickness skin grafts for massive (>100 cm(2)) chronic venous leg ulcers.

OBJECTIVE: Massive (≥100 cm(2)) venous leg ulcers (VLUs) demonstrate very low closure rates with standard compression therapy and are costly to manage. Negative-pressure wound therapy (NPWT), followed by a split-thickness skin graft (STSG), can be a cost-effective alternative to this standard care. We performed a cost analysis of these two treatments. METHODS: A retrospective review was performed of 10 ulcers treated with surgical debridement, 7 days of inpatient NPWT with topical antiseptic instillation (NPWTi), and STSG, with 4 additional days of inpatient NPWT bolster over the graft. Independent medical cost estimators were used to compare the cost of this treatment protocol with standard outpatient compression therapy. RESULTS: The average length of time ulcers were present before patients entered the study was 38 months (range, 3-120 months). Eight of 10 patients had complete VLU closure by 6 months after NPWTi with STSG. The 6-month costs of the proposed treatment protocol and standard twice-weekly compression therapy were estimated to be $27,000 and $28,000, respectively. CONCLUSIONS: NPWTi with STSG treatment is more effective for closure of massive VLUs at 6 months than that reported for standard compression therapy. Further, the cost of the proposed treatment protocol is comparable with standard compression therapy.

Bipolar disorder type 1 and schizophrenia are accompanied by decreased density of parvalbumin- and somatostatin-positive interneurons in the parahippocampal region.

GABAergic interneurons synchronize network activities and monitor information flow. Post-mortem studies have reported decreased densities of cortical interneurons in schizophrenia (SZ) and bipolar disorder (BPD). The entorhinal cortex (EC) and the adjacent subicular regions are a hub for integration of hippocampal and cortical information, a process that is disrupted in SZ. Here we contrast and compare the density of interneuron populations in the caudal EC and subicular regions in BPD type I (BPD-I), SZ, and normal control (NC) subjects. Post-mortem human parahippocampal specimens of 13 BPD-I, 11 SZ and 17 NC subjects were used to examine the numerical density of parvalbumin-, somatostatin- or calbindin-positive interneurons. We observed a reduction in the numerical density of parvalbumin- and somatostatin-positive interneurons in the caudal EC and parasubiculum in BPD-I and SZ, but no change in the subiculum. Calbindin-positive interneuron densities were normal in all brain areas examined. The profile of decreased density was strikingly similar in BPD-I and SZ. Our results demonstrate a specific reduction of parvalbumin- and somatostatin-positive interneurons in the parahippocampal region in BPD-I and SZ, likely disrupting synchronization and integration of cortico-hippocampal circuits.

Hippocampal interneurons are abnormal in schizophrenia.

OBJECTIVE: The cellular substrate of hippocampal dysfunction in schizophrenia remains unknown. We tested the hypothesis that hippocampal interneurons are abnormal in schizophrenia, but that the total number of hippocampal neurons in the pyramidal cell layer is normal. METHODS: We collected whole hippocampal specimens of 13 subjects with schizophrenia and 20 matched healthy control subjects to study the number of all neurons, the somal volume of neurons, the number of somatostatin- and parvalbumin-positive interneurons and the messenger RNA levels of somatostatin, parvalbumin and glutamic acid decarboxylase 67. RESULTS: The total number of hippocampal neurons in the pyramidal cell layer was normal in schizophrenia, but the number of somatostatin- and parvalbumin-positive interneurons, and the level of somatostatin, parvalbumin and glutamic acid decarboxylase mRNA expression were reduced. CONCLUSIONS: The study provides strong evidence for a specific defect of hippocampal interneurons in schizophrenia and has implications for emerging models of hippocampal dysfunction in schizophrenia.

Hippocampal interneurons in bipolar disorder.

CONTEXT: Postmortem studies have reported decreased density and decreased gene expression of hippocampal interneurons in bipolar disorder, but neuroimaging studies of hippocampal volume and function have been inconclusive. OBJECTIVE: To assess hippocampal volume, neuron number, and interneurons in the same specimens of subjects with bipolar disorder and healthy control subjects. DESIGN: Whole human hippocampi of 14 subjects with bipolar disorder and 18 healthy control subjects were cut at 2.5-mm intervals and sections from each tissue block were either Nissl-stained or stained with antibodies against somatostatin or parvalbumin. Messenger RNA was extracted from fixed tissue and real-time quantitative polymerase chain reaction was performed. SETTING: Basic research laboratories at Vanderbilt University and McLean Hospital. SAMPLES: Brain specimens from the Harvard Brain Tissue Resource Center at McLean Hospital. MAIN OUTCOME MEASURES: Volume of pyramidal and nonpyramidal cell layers, overall neuron number and size, number of somatostatin- and parvalbumin-positive interneurons, and messenger RNA levels of somatostatin, parvalbumin, and glutamic acid decarboxylase 1. RESULTS: The 2 groups did not differ in the total number of hippocampal neurons, but the bipolar disorder group showed reduced volume of the nonpyramidal cell layers, reduced somal volume in cornu ammonis sector 2/3, reduced number of somatostatin- and parvalbumin-positive neurons, and reduced messenger RNA levels for somatostatin, parvalbumin, and glutamic acid decarboxylase 1. CONCLUSION: Our results indicate a specific alteration of hippocampal interneurons in bipolar disorder, likely resulting in hippocampal dysfunction.

Lovastatin potentiates the antidepressant efficacy of fluoxetine in rats.

BACKGROUND: Cholesterol may have a role in the pathophysiology of depression. Lowering cholesterol levels with statins reduces risks for cardiovascular events, and there is clinical evidence that statins exert neuroprotective properties not fully explained by their effects on serum cholesterol levels. Altered cholesterol levels can affect serotonergic neurotransmission, which might be involved in the clinical efficacy of standard antidepressants. METHODS: We examined interactions between a statin (lovastatin) and a selective serotonin reuptake inhibitor (fluoxetine) using the forced swim test (FST) in rats, a behavioral assay that identifies treatments with antidepressant effects in humans. Specifically, we determined if the addition of lovastatin to the diet would increase the efficacy of a subeffective dose of fluoxetine. RESULTS: Rats maintained on a lovastatin-enriched diet for 30 days were more sensitive to the antidepressant-like effects of a low (subthreshold) dose of fluoxetine. The behavior of rats treated with this combination resembled that normally seen with higher doses of fluoxetine. No effects were observed in rats maintained on a lovastatin-enriched diet for 3 days. CONCLUSIONS: Lovastatin can augment the antidepressant-like effects of a low dose of fluoxetine in rats, raising the possibility that statins could be used to facilitate the effects of antidepressants in humans.