A cryogenic ice setup to simulate carbon atom reactions in interstellar ices

The design, implementation, and performance of a customized carbon atom beam source for the purpose of investigating solid-state reaction routes in interstellar ices in molecular clouds are discussed. The source is integrated into an existing ultrahigh vacuum setup, SURFace REaction SImulation DEvice (SURFRESIDE²), which extends this double atom (H/D, O, and N) beamline apparatus with a third atom (C) beamline to a unique system that is fully suited to explore complex organic molecule solid-state formation under representative interstellar cloud conditions. The parameter space for this system is discussed, which includes the flux of the carbon atoms hitting the ice sample, their temperature, and the potential impact of temperature on ice reactions. Much effort has been put into constraining the beam size to within the limits of the sample size with the aim of reducing carbon pollution inside the setup. How the C-atom beam performs is quantitatively studied through the example experiment, C + ¹⁸O₂, and supported by computationally derived activation barriers. The potential for this source to study the solid-state formation of interstellar complex organic molecules through C-atom reactions is discussed.

Major neonatal surgery under local anesthesia: a cohort study from Bangladesh

BACKGROUND

Surgeons and anesthetists must respond to the perioperative mortality associated with general anesthesia in developing countries. The safety of performing major neonatal surgery under local anesthesia is one pragmatic response. This study describes and evaluates such practice in a tertiary pediatric surgery center in Bangladesh.

METHODS

Seven hundred and twenty neonates were admitted for major surgery during a 3.5-year study period. Hundred and fifty two neonates died pre-operatively, and 568 underwent major neonatal surgery. 352 (62.0%) neonates were operated under general anesthesia, while the 216 most fragile neonates (38.0%) were operated with local infiltrative anesthesia alone. Medical files were reviewed; data were collected prospectively; mortality risk factors were assessed by univariate and multivariate analysis.

RESULTS

Two hundred and sixteen procedures were performed under local anesthesia: sigmoid colostomies (37.5%), laparotomies with anastomosis (21.3%), anoplasties (18.1%), laparotomies with enterostomy (8.3%), closures of abdominal wall defects (6.9%), fixations of silastic bags (3.7%), peritoneal tube drainage (2.3%), and gastrostomies (1.9%). Median weight was 2,400 g (2,200-2,460), median gestational age was 37.0 weeks (36.0-38.0), and median age at surgery was 5.0 days (3.0-14.7). In-hospital postoperative mortality was 10.6% among those selected for local anesthesia, and 11.4% among neonates operated under general anesthesia. Low birth weight was an independent risk factor for mortality on multivariate analysis (OR 1.002 g(-1), 95% CI [1.000-1.004], p = 0.029).

CONCLUSIONS

Local anesthesia is an established option for the most fragile neonates with major surgical disease. Safe anesthesia ought to be accessible to all children of the world. The global pandemic of perioperative mortality needs to be addressed.

In hydronephrosis less than 10 % kidney function is not an indication for nephrectomy in children

PURPOSE

To reduce the incidence of nephrectomy or hydronephrosis in children.

MATERIALS AND METHODS

From September 1998 to October 2000, we treated 58 patients with hydronephrosis; their ages ranged from 35 days to 11 years (mean age 4 years 7 months). All patients were subjected to a DTPA renogram with split function. In 12 patients (study group), kidney function was less than 10 % (range 0 - 10 %). Initially, nephrostomy was carried out in all 12 patients followed by Anderson-Hyne's pyeloplasty after 4 - 6 weeks. Postoperatively renal USG, urine r/m/e & c/s (routine and microscopic examination and culture and sensitivity test), blood urea, serum creatinine were assessed and DMSA scan and DTPA renogram with split functions were carried out in all patients.

RESULTS

In the study group, all 12 patients showed improvement of renal function (more than 10 %) after nephrostomy and in all of them pyeloplasty was subsequently carried out within 4 - 6 weeks. There were no significant pre-, peri- or postoperative complications.

CONCLUSIONS

Contrary to common practice we do not recommend nephrectomy for hydronephrotic kidneys which show < 10 % of renal function on renogram. The renal functional status improves significantly after a preliminary nephrostomy, thus avoiding the need for a straightforward nephrectomy in children along with all the possible long-term effects of a single kidney.