Massive-Star Supernovae as Major Dust Factories

We present late-time optical and mid-infrared observations of the Type-II supernova 2003gd in NGC 628. Mid-infrared excesses consistent with cooling dust in the ejecta are observed 499-678 days after outburst, and are accompanied by increasing optical extinction and growing asymmetries in the emission-line profiles. Radiative-transfer models show that up to 0.02 solar masses of dust has formed within the ejecta, beginning as early as 250 days after outburst. These observations show that dust formation in supernova ejecta can be efficient and that massive-star supernovae can be major dust producers throughout the history of the Universe.Comment: 11 pages, 1 figure. Accepted 2006 May 30 for publication in Science; Published in 2006 Jun 8 edition of Science Express; 2nd version fixes minor change in conclusion made in pres

A Systematic Study of Mid-Infrared Emission from Core-Collapse Supernovae with Spirits

The American Astronomical Society. All rights reserved.We present a systematic study of mid-infrared emission from 141 nearby supernovae (SNe) observed with Spitzer/IRAC as part of the ongoing SPIRITS survey. We detect 8 Type Ia and 36 core-collapse SNe. All Type Ia/Ibc SNe become undetectable within three years of explosion, whereas 22 ± 11% of Type II SNe continue to be detected. Five Type II SNe are detected even two decades after discovery (SN 1974E, 1979C, 1980K, 1986J, and 1993J). Warm dust luminosity, temperature, and a lower limit on mass are obtained by fitting the two IRAC bands, assuming an optically thin dust shell. We derive warm dust masses between 10-6 and 10-2 M o and dust color temperatures between 200 and 1280 K. This observed warm dust could be pre-existing or newly created, but in either case represents a lower limit to the dust mass because cooler dust may be present. We present three case studies of extreme SNe. SN 2011ja (II-P) was over-luminous ([4.5] = -15.6 mag) at 900 days post explosion with increasing hot dust mass, suggesting either an episode of dust formation or intensifying circumstellar material (CSM) interactions heating up pre-existing dust. SN 2014bi (II-P) showed a factor of 10 decrease in dust mass over one month, suggesting either dust destruction or reduced dust heating. The IR luminosity of SN 2014C (Ib) stayed constant over 800 days, possibly due to strong CSM interaction with an H-rich shell, which is rare among stripped-envelope SNe. The observations suggest that this CSM shell originated from an LBV-like eruption roughly 100 years pre-explosion. The observed diversity demonstrates the power of mid-IR observations of a large sample of SNe. © 2017

The Long-term Effects of Gastric Bypass on Vitamin D Metabolism

OBJECTIVE: Alterations of the endocrine system in patients following Roux-en-Y gastric bypass (GBP) are poorly described and have prompted us to perform a longitudinal study of the effects of GBP on serum calcium, 25-hydroxy-vitamin-D (vitamin D), and parathyroid hormone (PTH). METHODS: Prospectively collected data were compiled to determine how GBP affects serum calcium, vitamin D, and PTH. Student t test, Fisher exact test, or linear regression was used to determine significance. RESULTS: Calcium, vitamin D, and PTH levels were drawn on 243 patients following GBP. Forty-one patients had long-limb bypass (LL-GBP), Roux >100 cm, and 202 had short-limb bypass (SL-GBP), Roux ≤100 cm. The mean (±SD) postoperative follow-up time was significantly longer in the LL-GBP group (5.7 ± 2.5 years) than the SL-GBP group (3.1 ± 3.6 years, P < 0.0001). When corrected for albumin levels, mean calcium was 9.3 mg/dL (range, 8.5–10.8 mg/dL), and no difference existed between LL-GBP and SL-GBP patients. For patients with low vitamin D levels (<8.9 ng/mL), 88.9% had elevated PTH (>65 pg/mL) and 58.0% of patients with normal vitamin D levels (≥8.9 ng/mL) had elevated PTH (P < 0.0001). In individuals with vitamin D levels <30 ng/mL, 55.1% (n = 103) had elevated PTH, and of those with vitamin D levels ≥30 ng/mL 28.5% (n = 16) had elevated PTH (P = 0.0007). Mean vitamin D levels were lower in patients who had undergone LL-GBP as opposed to those with SL-GBP, 16.8 ± 10.8 ng/mL versus 22.7 ± 11.1 ng/mL (P = 0.0022), and PTH was significantly higher in patients who had a LL-GBP (113.5 ± 88.0 pg/mL versus 74.5 ± 52.7 pg/mL, P = 0.0002). There was a linear decrease in vitamin D (P = 0.005) coupled with a linear increase in PTH (P < 0.0001) the longer patients were followed after GBP. Alkaline phosphatase levels were elevated in 40.3% of patients and correlated with PTH levels. CONCLUSION: Vitamin D deficiency and elevated PTH are common following GBP and progress over time. There is a significant incidence of secondary hyperparathyroidism in short-limb GBP patients, even those with vitamin D levels ≥30 ng/mL, suggesting selective Ca(2+) malabsorption. Thus, calcium malabsorption is inherent to gastric bypass. Careful calcium and vitamin D supplementation and long-term screening are necessary to prevent deficiencies and the sequelae of secondary hyperparathyroidism

Safety, Feasibility, and Short-term Outcomes of Laparoscopic Ileal-Pouch-Anal Anastomosis: A Single Institutional Case-Matched Experience

OBJECTIVE: To compare safety and short-term outcomes of 100 laparoscopic ileal pouch-anal anastomosis (IPAA) versus 200 conventional open IPAA patients. SUMMARY BACKGROUND DATA: Outcomes of laparoscopic IPAA (LAP-IPAA) have been incompletely characterized. Previous reports are characterized by small numbers of patients and rarely include case-matched or randomized trial methodology. This report describes 100 LAP-IPAA patients case matched to 200 open IPAA patients. METHODS: Between 1998 and 2004, 100 consecutive LAP-IPAA patients (75 laparoscopic assisted, 25 hand assisted) were identified and case matched to 200 open IPAA control patients by age, operation, gender, date of operation, and body mass index. Operative and postoperative outcomes at 90 days were compared. RESULTS: A total of 300 patients (180 female) with a median age of 32 years (range, 17–66 years), and a median body mass index of 23 kg/m(2) (range, 16–34 kg/m(2)) underwent IPAA (100 LAP-IPAA, 200 open IPAA). Diagnosis (chronic ulcerative colitis 97%, familial adenomatous polyposis 3%) and previous operative history were equivalent between groups. One intraoperative complication occurred in each group. Overall, the laparoscopic conversion rate was 6%. Median operative time was longer for the LAP-IPAA group (333 minutes versus 230 minutes, P < 0.0001). LAP-IPAA patients had shorter median time to regular diet (3 versus 5 days), time to ileostomy output (2 versus 3 days), length of stay (4 versus 7 days), and decreased IV narcotic use (all P < 0.05.Postoperative morbidity was equivalent (LAP-IPAA = 33%, open IPAA = 37%), mortality was nil, and readmission rates were equal (LAP-IPAA = 21%, open IPAA = 22%). Reoperation was required in 3% of LAP-IPAA and 6.5% of open IPAA patients (P < 0.2) during the first 3 months. CONCLUSION: LAP-IPAA is equivalent to open IPAA in terms of safety and feasibility. In addition, LAP-IPAA provides significant improvements in short-term recovery outcomes

The activity of gastric ghrelin positive cells in obese patients treated surgically.

Ghrelin is a 28 amino acid peptide hormone regulating food intake and stimulating releasement of growth hormone. It is produced in a distinct endocrine call known as X/A - like cells. The most abundant source of this very important factor in energy homeostasis is gastric fundus. Regulatory mechanisms of ghrelin synthesis and secretion in physiological and pathological states are not discovered completely. The aim of our study was evaluation of the activity of gastric X/A-like cells in obese patients before and after the most popular surgical bariatric procedures - Roux - Y Gastric Bypass (RYGB) and Laparoscopic Adjustable Gastric Banding (LAGB). Obese patients in number 18 took part in the study. LAGB was performed in 7 patients and RYGB in 11 patients. Peripheral blood was taken from each patient before operation and first day, seventh day, one month and three months after surgery. Ghrelin level was determined by RIA technique. The specimen of stomach was taken from circular stapler after gastrojejunostomy during RYGB and immunohistochemical study of gastric mucosa, using the EnVision method and specific monoclonal antybodies against ghrelin was performed. The intensity of ghrelin-immunoreactivity in X/A-like cells was analyzed using Olympus Cell D image analysis system. Efficiency of bariatric procedures was estimated by EWL- excess weight loss. We observed very strong immunohistochemical reactions of gastric X/A-like cells, accompanied by lower ghrelin plasma concentration, in comparison to the control group. LAGB procedure induced increase of ghrelin plasma level while RYGB procedure induced decrease of this hormone. The main finding of the present study is the hypoactivity of gastric X/A-like cells in obese patients in comparison to the control group