Visualization of Astronomical Nebulae via Distributed Multi-GPU Compressed Sensing Tomography

The 3D visualization of astronomical nebulae is a challenging problem since only a single 2D projection is observable from our fixed vantage point on Earth. We attempt to generate plausible and realistic looking volumetric visualizations via a tomographic approach that exploits the spherical or axial symmetry prevalent in some relevant types of nebulae. Different types of symmetry can be implemented by using different randomized distributions of virtual cameras. Our approach is based on an iterative compressed sensing reconstruction algorithm that we extend with support for position-dependent volumetric regularization and linear equality constraints. We present a distributed multi-GPU implementation that is capable of reconstructing high-resolution datasets from arbitrary projections. Its robustness and scalability are demonstrated for astronomical imagery from the Hubble Space Telescope. The resulting volumetric data is visualized using direct volume rendering. Compared to previous approaches, our method preserves a much higher amount of detail and visual variety in the 3D visualization, especially for objects with only approximate symmetry.

Outcome after intestinal transplantation: results from one center's 9-year experience; discussion 1031-2

HYPOTHESIS

Outcomes after intestinal transplantation have improved during the past decade with refinements in surgical techniques as well as advances in immunosuppression and antimicrobial therapy.

DESIGN

Retrospective analysis.

SETTING

Tertiary care medical center, August 1991 through December 2000.

PATIENTS

Adult (5) and pediatric (12) patients with intestinal failure. All developed complications from long-term total parenteral nutrition therapy. Median age was 8.6 years and median weight was 22 kg.

INTERVENTIONS

Primary intestinal transplantation with (n = 14) or without (n = 3) the liver.

MAIN OUTCOME MEASURES

Patient and graft survival, viral infections, rejection, and nutritional autonomy.

RESULTS

Twenty-one intestinal grafts were transplanted into the 17 recipients. All donors were cadaveric and were matched by ABO blood group and size. Patient survival at 1 and 3 years was 63% and 55%, respectively. Death-censored graft survival at 1 and 3 years was 73% and 55%, respectively. There were 1.5 acute cellular rejection episodes per graft and 3 grafts were lost to rejection. Incidences of infection with the Epstein-Barr virus and cytomegalovirus were negligible with aggressive prophylaxis and preemptive therapy. Nutritional autonomy was achieved in 69% of grafts surviving more than 30 days after intestinal transplantation.

CONCLUSIONS

Intestinal transplantation is now the standard of therapy for patients with intestinal failure and complications resulting from total parenteral nutrition. Outcomes have markedly improved since initiation of the program. Aggressive immunosuppression as well as prophylaxis and preemptive antiviral therapy have led to low incidences of acute cellular rejection, Epstein-Barr virus, and cytomegalovirus. Finally, nutritional autonomy can be achieved after successful intestinal transplantation.

Thoughts from an emergency room, Littleton, Colorado

Images

Isolation and characterization of the mouse homolog of the preprodynorphin (Pdyn) gene

We have isolated and sequenced the mouse preprodynorphin gene (Pdyn). The Pdyn gene can encode for six biologically active dynorphin peptides. The predicted mouse preprodynorphin has 90%, 67%, and 66% identity with the predicted rat, porcine, and human preprodynorphins, respectively. Using an RT-PCR technique, we show that the Pdyn gene starts being expressed at embryonic day 12.5, with a steep increase of expression by embryonic day 14.5; in the adult mouse it is expressed in the brain, but not in liver, heart, spleen, or kidney.

Long-term results of pediatric liver transplantation: an analysis of 569 transplants

OBJECTIVE

To analyze a single center's 13-year experience with 569 pediatric orthotopic liver transplants for end-stage liver disease.

SUMMARY BACKGROUND DATA

Despite advances in medical therapy, liver replacement continues to be the only definitive mode of therapy for children with end-stage liver disease. Innovative surgical techniques and improved immunosuppression have broadened the application of liver replacement for affected children. However, liver transplantation in the child remains challenging because of the scarcity of donor organs, complex surgical technical demands, and the necessity to prevent long-term complications.

METHODS

The medical records of 440 consecutive patients younger than 18 years of age undergoing orthotopic liver transplantation for end-stage liver disease from March 20, 1984, to November 15, 1997, were reviewed. Results were analyzed using Cox multivariate regression analysis to determine the statistical strength of independent associations between pretransplant covariates and patient and graft survival. Actuarial patient and graft survival rates were determined at 1, 3, 5, and 10 years. The type and incidence of posttransplant complications were determined, as was the quality of long-term allograft function. The median follow-up period was 4.1 years.

RESULTS

Biliary atresia was the most common cause (50.4%) of endstage liver disease in this patient population. The median recipient age was 2.4 years; 239 patients (54%) were younger than 3 years of age and 1 11 patients (25%) were younger than 1 year of age. There were 471 whole organs, 29 were ex vivo reduced size, 33 were living-related donor, and 36 were in situ split-liver allografts. Three hundred forty-three (78%) patients underwent a single allograft, whereas 97 patients required retransplantation; hepatic artery thrombosis was the most common indication for retransplantation (55 patients). The 1-, 3-, 5-, and 10-year actuarial patient survival rates were 82%, 80%, 78%, and 76%, respectively; allograft survival rates were 68%, 63%, 60%, and 54%. Long-term liver function remains excellent: current median follow-up values for total bilirubin and aspartate aminotransferase were 0.5 mg/dl and 54 IU/L, respectively. Cox multivariate regression analysis demonstrated that pretransplant patient age, the era of transplantation, and the number of allografts performed significantly and independently predicted patient survival rates, whereas allograft type and pretransplant diagnosis did not.

CONCLUSIONS

Liver transplantation in the pediatric patient is a durable procedure that provides excellent long-term survival. Although there have been overall improvements in patient outcome with increased experience, the effect is most pronounced for patients younger than 1 year of age. Retransplantation, although effective in a meaningful number of patients, continues to carry a progressive decrement in survival with the number of allografts performed. Use of living-related and in situ split-liver allografts has dramatically reduced waiting times for small children and has improved patient survival.

Current use and clinical outcome of home parenteral and enteral nutrition therapies in the United States

BACKGROUND & AIMS

Home nutrition support, especially when delivered parenterally, is very costly. The aim of this study is to examine current usage of home parenteral and enteral nutrition (HPEN) in the United States and the quality of therapy outcome.

METHODS

Medicare HPEN use from 1989 to 1992 was analyzed to assess use, growth, and costs. National Registry information collected on 9288 patients treated with HPEN from 1985 to 1992 was used to assess disease distribution and therapy outcome.

RESULTS

In the United States, there were approximately 40,000 parenteral and 152,000 enteral home patients in 1992. The usage of HPEN doubled between 1989 and 1992, and a large proportion was in patients with short survival. The prevalence of HPEN in the United States was 4-10 times higher than in other Western countries. Outcome data showed both therapies were relatively safe. The primary disease strongly influenced survival and rehabilitation, and age, per se, was not a reason to deny HPEN.

CONCLUSIONS

Predicted quality survival at home for several months, rather than a specific diagnosis, seems to be the soundest justification for HPEN. Its role in terminal conditions and patients without primary gastrointestinal diseases needs further evaluations.

Adaptation of rabbit small intestinal brush-border membrane enzymes after extensive bowel resection

Short lengths of small intestine may be resected without significantly affecting the digestive and absorptive capacity; however, extensive resection produces varying degrees of malnutrition. This study was undertaken to define the adaptive changes in the remaining small intestine of two of the jejunal and ileal mucosal brush-border membrane enzymes after extensive small bowel resection in rabbits. Thirty adult New Zealand White rabbits underwent a 50% to 60% jejuno-ileal-enterectomy with end-to-end anastomosis. Maltase activity (UE/g protein) increased from 152 (preoperative) to 392 at 3 weeks in the proximal segment and from 85 to 259 in the distal segment; these levels decreased to 222 and 155 in the respective segments at 6 weeks. AOP activity (UE/g protein) increased from 154 (preoperative) to 171 in the proximal segment and 171 to 256 in the distal segment at 3 weeks, and was 131 and 288 in the respective segments at 6 weeks. This marked increase in the mucosal brush-border enzymatic activities at 3 weeks postoperatively was associated with a 28% increase in bowel length. By 6 weeks the enzyme levels had decreased slightly; however, there was a persistent 41% increase in bowel length over that immediately postoperation. The mucosal surface area increased from 295 mm2 immediately postoperation to 5,337 mm2 at 3 weeks and 7,635 mm2 at 6 weeks, a 250% increase. The authors conclude that there is an immediate compensatory increase in villus length as well as brush-border enzymatic expression in the remaining intestine that gradually declines as the small intestinal surface area continues to increase and the bowel lengthens with time.

Copper deficiency secondary to a copper transport defect: a new copper metabolic disturbance

We describe a 21-year-old man who developed copper deficiency manifested as a demyelinating neuropathy, chronic intestinal pseudo-obstruction, osteoporosis, testicular failure, retinal degeneration, and cardiomyopathy with a tortuous aorta. His serum copper was low and did not increase despite administration of large doses of intravenous copper sulfate. The ceruloplasmin level as measured by an antibody technique was normal, yet ceruloplasmin (Cp) oxidase activity was very low. The Cp amino acid sequence was normal. This suggests that the copper deficiency was caused by a defect in hepatic processing of copper for incorporation into Cp.

Milk tolerance in adults with ulcerative colitis

OBJECTIVES

There has been concern in the literature and among physicians and patients that milk intolerance may contribute to disease activity in ulcerative colitis. We sought to define whether patients with ulcerative colitis have problems with milk tolerance.

METHODS

1) A questionnaire was administered to a group of gastroenterologists. 2) Consecutive unselected ulcerative colitis patients were administered a questionnaire regarding issues concerning their ingestion and tolerance of milk products. 3) Patients, and age- and ethnically matched controls, underwent lactose hydrogen breath testing at a 50-g dose, and if intolerant, returned for testing at a 12.5-g dose.

RESULTS

Eighty percent of responding physicians stated that they recommend avoidance of milk products at some time to their patients. Thirteen of 29 (44%) ulcerative colitis patients were lactose intolerant compared with five of 14 (36%) controls (p = 0.57). Of 11 subjects returning for the 12.5-g test dose, only three (28%) were intolerant. Of 10 ulcerative colitis patients tested during a flare, only two (20%) were intolerant. Nineteen of 28 (66%) patients reduced or eliminated milk products from their diet, but only 10 (45%) of these patients were lactose intolerant. The discordance rate for predicting lactose tolerance status among patients was 35%. By logistic regression analysis, age (p = 0.04) and ethnicity (p = 0.006) were the only variables that were predictive of an abnormal lactose hydrogen breath test.

CONCLUSIONS

There are common misperceptions among physicians and patients about lactose intolerance in ulcerative colitis. Lactose intolerance in patients with ulcerative colitis is dependent on their age and ethnicity and not any particular aspects of their disease. The proscription of milk products during flares of disease by many physicians is not supported by this study.

Nutritional issues in pediatric inflammatory bowel disease

Malnutrition, characterized by weight loss, growth failure and micronutrient depletion, are prominent features of inflammatory bowel disease (IBD) in the pediatric age group. Accurate evaluation of the patient's nutritional status and appropriate nutritional support, whether enteral or parenteral, constitute integral parts of the management of the growing child with IBD. Over the past two decades, a number of studies have supported the potential use of nutritional therapy to induce remission and to control disease activity in symptomatic Crohn's disease. More recently, preliminary studies on the use of dietary supplements of marine-oil-derived omega-3 fatty acids have also indicated a beneficial effect in IBD patients. In parallel with these clinical trials, scientific research has recently focused on the concept that specific dietary alterations can modulate the immune response. Components of the diet that may have particular relevance to mucosal immunity and the pathogenesis of IBD include polyunsaturated fatty acids, nucleotides, and amino acids such as glutamine and arginine. Future research in the interactions between specific nutrients and the immune system will likely increase our understanding of the causes of IBD, as well as enhance the development of novel nutritional therapies for IBD patients.

Alport's syndrome and achalasia

A 7-year-old boy presented with a history of postprandial vomiting, failure to thrive, hematuria, proteinuria and decreased renal function. Electron microscopy of a renal biopsy specimen demonstrated the typical glomerular basement membrane changes associated with Alport's syndrome. Audiometry revealed a moderate bilateral high-tone sensorineural hearing loss. Bilateral anterior lenticonus and a unilateral cataract were also diagnosed. Achalasia diagnosed radiologically and confirmed by biopsy was corrected by surgery. Evaluations of the parents and three siblings were negative. The patient subsequently developed end-stage renal failure. This case report and a review of the literature suggest that achalasia may be part of Alport's syndrome in some patients.

Somatic growth and developmental functioning in children receiving prolonged home total parenteral nutrition

Growth and psychomotor development in nine infants receiving prolonged home total parenteral nutrition (TPN) were studied longitudinally from infancy to 3 years of age. Although these children had received TPN for, on average, 79% of their lives, normalization of somatic growth occurred by 2 years of age in all of them. Three children maintained average or above average levels of developmental performance over the 3-year study period. Another four children had initially delayed development but average or above average developmental scores by 18 months. In two children the rate of development gradually slowed without obvious cause, so that by 3 years they functioned in the below average to mildly retarded range.

[Bile duct stricture in childhood. A diagnostic challenge (author's transl)]

5 cases of biliary stricture, 3 congenital, 1 malignant and 1 blunt traumatic are reported in 3 infants and 2 children. Jaundice is present in 4 patients only and is delayed in 2. Alkalin phosphatases are constantly elevated but ultrasound studies negative in 3 patients. Diagnosis was made by percutaneous cholangiography in 2 and per-operative cholangiogram in 3. Roux en Y hepaticojejunostomy is successfully performed in 4. Bile duct stricture is a rare cause of cholestatic jaundice in childhood and an even rarer sequela of blunt trauma. This series demonstrates the usefulness of percutaneous transhepatic cholangiography, more accurate than ultra-sonography in investigating cholestasis in childhood.

Cell-mediated immune defects and infection. A study of malnourished hospitalized children

Severe protein calorie malnutrition in children in developing countries has been characterized by noticeable depression of cell-mediated immunity and an increased manifestation of infectious illnesses. We studied 23 hospitalized US children whose admitting diagnoses included severe malnutrition to see if similar findings existed. Children were divided into two groups based on the percentage of E rosettes (T cells) prior to nutritional therapy. Those with E rosette values less than 50% were considered to have noticeably abnormal cell-mediated immunity. Eleven of the 23 patients who had rosette values less than 50% had 18 clinical infections, including four episodes of sepsis. One of the 23 children with normal (> 50%) E rosettes had one minor infection. It was concluded that depressed cellular immunity as measured by E rosette is associated with an increased incidence of infectious illness in the malnourished hospitalized pediatric patient in the United States. Other defects in host defenses, ie, defects in complement and phagocytic function, may also have contributed to the increased number of clinical infections noted in these patients.

Diagnosis and treatment of duodenal ulcer in infancy and childhood

An awareness of the modes of presentation in childhood duodenal ulcer disease is necessary for prompt diagnosis and treatment. Therapy should be based on the rationale of decreasing acid secretion and providing adequate buffering of gastric acid throughout the day. Because of the high incidence of recurrence in children, aggressive diagnosis and treatment of duodenal ulcer are indicated in any child suspected of having the disease.

Gastroesophageal fundoplication for reflux in infants and children

Fifteen infants and young children with symptomatic gastroesophageal reflux underwent fundoplication during a 6 1/2-yr period. Standard barium esophagrams clearly demonstrated reflux in only 10 of the 15 patients; however, cine esophagrams indicated reflux in the remaining patients. Esophagoscopy with mucosal biopsy demonstrated esophagitis in 9 of the 10 patients in whom it was performed, and it is a very helpful diagnostic procedure. Esophageal manometry showed low sphincter pressures in each of 7 patients. Fundoplication was performed when there was (1) persistent reflux after a 3-wk hospital course of vigorous medical management, (2) failure to gain weight, (3) malnutrition, (4) recurrent aspiration, (5) esophagitis, or (6) stricture. Concomitant gastrostomy prevented the gas bloat syndrome in all patients. All strictures were successfully relieved by postoperative dilatation (average four per patient). Esophageal replacement is rarely indicated for strictures due to reflux in children. No deaths or major complications occurred following operation. Each of the patients has been relieved of clinical reflux, and each has gained weight more rapidly than preoperatively. Follow-up esophagrams on each of the patients show absence of reflux, and manometry shows the low esophageal sphincter pressure to be increased an average of 10 mm Hg above preoperative values. Since the results of Nissen fundoplication to correct reflux in infants and young children are highly satisfactory, and since the consequences of persistent reflux may be severe, a fairly aggressive approach should be taken in the management of symptomatic reflux.