Short term safety of magnetic sphincter augmentation vs minimally invasive fundoplication: an ACS-NSQIP analysis

PURPOSE

Magnetic Sphincter Augmentation (MSA) is an FDA-approved anti-reflux procedure with comparable outcomes to fundoplication. However, most data regarding its use are limited to single or small multicenter studies which may limit the generalizability of its efficacy. The purpose of this study is to evaluate the outcomes of patients undergoing MSA vs fundoplication in a national database.

MATERIALS AND METHODS

The 2017-2020 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Registry was utilized to evaluate patients undergoing MSA or fundoplication. Patients requiring Collis gastroplasty, paraesophageal hernia repair, and emergency cases, were excluded. Patient outcomes included overall complication rates, readmissions, reoperations, and mortality.

RESULTS

A total of 7,882 patients underwent MSA (n = 597) or fundoplication (n = 7285). MSA patients were younger (51 vs 57, p < 0.001), and more often male (49.6 vs 34.3%, p < 0.001). While patients undergoing MSA experienced similar rates of reoperation (1.0 vs 2.0%, p = 0.095), they experienced fewer readmissions (2.2 vs 4.7%, p = 0.005), complications (0.6 vs 4.0%, p < 0.001), shorter mean (SD) hospital length of stay(days) (0.4 ± 4.3 vs 1.8 ± 4.6, p < 0.001) and operative time(min) (80.8 ± 36.1 vs 118.7 ± 63.7, p < 0.001). Mortality was similar between groups (0 vs 0.3%, p = 0.175). On multivariable analysis, MSA was independently associated with reduced postoperative complications (OR 0.23, CI 0.08 to 0.61, p = 0.002), readmissions (OR 0.53, CI 0.30 to 0.94, p = 0.02), operative time (RC - 36.56, CI - 41.62 to - 31.49. p < 0.001) and length of stay (RC - 1.22, CI - 1.61 to - 0.84 p < 0.001).

CONCLUSION

In this national database study, compared to fundoplication MSA was associated with reduced postoperative complications, fewer readmissions, and shorter operative time and hospital length of stay. While randomized trials are lacking between MSA and fundoplication, both institutional and national database studies continue to support the use of MSA as a safe anti-reflux operation.

A direct experimental comparison of single-crystal CVD diamond and silicon carbide X-ray beam position monitors

Single-crystal chemical vapour deposition (CVD) diamond detectors are an established transmissive synchrotron beamline diagnostic instrument used for beam position and beam intensity monitoring. A recently commercialized alternative is silicon carbide (4H-SiC) devices. These have the potential to provide the same diagnostic information as commercially available single-crystal CVD diamond X-ray beam position monitors, but with a much larger transmissive aperture. At Diamond Light Source an experimental comparison of the performance of single-crystal CVD diamond and 4H-SiC X-ray beam position monitors has been carried out. A quantitative comparison of their performance is presented in this paper. The single-crystal diamond and 4H-SiC beam position monitors were installed in-line along the synchrotron X-ray beam path enabling synchronous measurements at kilohertz rates of the beam motion from both devices. The results of several tests of the two position monitors' performance are presented: comparing signal uniformity across the surface of the detectors, comparing kHz intensity measurements, and comparing kHz beam position measurements from the detectors. Each test is performed with a range of applied external bias voltages. A discussion of the benefits and limitations of 4H-SiC and single-crystal CVD diamond detectors is included.

Co-design with aboriginal and torres strait islander communities: A journey

AIM

This paper explores the principles of co-design with Aboriginal and Torres Strait Islander communities by reflecting on the literature, learning from experiences of allied health professionals, and considering how co-design can be applied in rural and remote allied health practice.

CONTEXT

This paper has been authored by a working group from Services for Rural and Remote Allied Health (SARRAH). SARRAH is a member-based allied health organisation, working to improve health outcomes for rural and remote Australians. SARRAH has been representing and supporting allied health professionals in rural and remote Australia for over 20 years, with a member base that includes students, practitioners, programme managers, policy makers and academics. As a non-Indigenous organisation, SARRAH works in partnership and receives guidance from the peak organisation, Indigenous Allied Health Australia (IAHA).

APPROACH

Over a period of 3 months, a group of eleven SARRAH members and staff came together to review available literature, seek member perspectives and share their experiences and understandings of co-design. Working group discussions were grounded in the knowledge and experiences shared by two Aboriginal and Torres Strait Islander group members.

CONCLUSION

This paper proposes that successful co-design with Aboriginal and Torres Strait Islander communities places legitimate value on different knowledge systems, is built on strong and trusting relationships, promotes inclusive involvement and requires authentic partnerships. Using these principles, SARRAH will engage with members and stakeholders to influence meaningful change in allied health practice in rural and remote Australia.

Impact of Robotic Approach on Post-Anastomotic Leaks After Esophagectomy for Esophageal Cancer

INTRODUCTION

Although mortality rates after esophagectomy have decreased over the last 30 years, anastomotic leaks still commonly persist and portend significant morbidity. Previous studies have analyzed patient and perio-perative risk factors for leaks, yet data describing the association of leaks and an open or minimally invasive approach are lacking. The purpose of this study was to evaluate the impact of operative approach on leak rates and subsequent management of the leaks.

METHODS

We queried the Procedure-Targeted National Surgical Quality Improvement Program Database for patients undergoing esophagectomy for cancer in the years from 2016 to 2019. Patient demographics, disease-related information, peri-operative data, and short-term outcomes were reviewed. Multivariable, stepwise logistic regression analysis was performed to investigate factors associated with post-operative anastomotic leaks.

RESULTS

Of the 2696 patients who underwent esophagectomy for cancer, anastomotic leaks occurred in 374 (14%). Based on approach, 13% of open, 14% of laparoscopic, and 18% of robotic cases were complicated by leak (P = .123). Multivariable analysis identified the following significant risk factors for leak: diabetes (OR 1.32, P = .047), hypertension (OR 1.32, P = .022), and longer operative time (OR 1.61, P < .001). The percentage of leaks requiring endoscopic or operative intervention was 75% for open, 79% for laparoscopic, and 54% for robotic cases (P = .004).

CONCLUSIONS

Anastomotic leaks after esophagectomy for cancer occur frequently regardless of surgical approach. Furthermore, these leaks are managed differently after an open, laparoscopic, or robotic approach. Robotic esophagectomies complicated by anastomotic leak required less invasive management.

Electronic smart-hub based intervention during COVID-19 in a rural Psychiatry of Old Age service in North-West Ireland

Introduction

The COVID-19 pandemic caused significant disruptions in services and necessitated innovation to continue care provision to the vulnerable population of older adults with psychiatric needs.

Objectives

The objective of this study was to examine the experiences of staff and patients using a hands-free electronic smart-hub (eSMART hub) intervention to keep patients connected with psychiatry of old age following COVID-19 restrictions.

Methods

A risk stratification register was created of all patients known to the Psychiatry of Old Age service in the North-West of Ireland to identify those at highest risk of relapse. These patients were offered a smart-hub with remote communication and personal assistant technology to be installed into their homes. Smart-hubs were also installed in the team base to facilitate direct device to device communication. Semi-structured qualitative interviews were conducted with 10 staff members and 15 patients at 6-12 months following the installation of the smart-hubs.

Results

The smart-hubs were utilized by the POA team to offer remote interventions over video including clinician reviews, regular contact with key workers and day-hospital based therapeutic interventions such as anxiety management groups and OT led physical exercises. Patients also used the personal assistant aspect of the hub to attend to personal hobbies such as accessing music and radio. Positive feedback related to companionship during isolation and connectivity to services. Negative feedback was mainly related to technology, particularly internet access and narrow scope of communication abilities.

Conclusions

Electronic smart-hub devices may offer an acceptable avenue for remote intervention and communication for isolated high-risk older persons.

Disclosure

The smart hub devices used in this study were donated by Amazon. However, the company was not involved in any other aspect of the study and the researchers have no significant financial interest, consultancy or other relationship with products, manufactur

Modelling the effects of optical vibrations on photon beam parameters using ray-tracing software

A method to simulate beam properties observed at the beamline sample-point in the presence of motion of optical components has been developed at Diamond Light Source. A series of stationary ray-tracing simulations are used to model the impact on the beam stability caused by dynamic motion of optical elements. Ray-tracing simulations using SHADOW3 in OASYS, completed over multiple iterations and stitched together, permit the modelling of a pseudo-dynamic beamline. As beamline detectors operating at higher frequencies become more common, beam stability is crucial. Synchrotron ring upgrades to low-emittance lattices require increased stability of beamlines in order to conserve beam brightness. By simulating the change in beam size and position, an estimate of the impact the motion of various components have on stability is possible. The results presented in this paper focus on modelling the physical vibration of optical elements. Multiple beam parameters can be analysed in succession without manual input. The simulation code is described and the initial results obtained are presented. This method can be applied during beamline design and operation for the identification of optical elements that may introduce large errors in the beam properties at the sample-point.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Management of lateral abdominal hernias

PURPOSE

Lateral abdominal wall hernias are rare defects but, due to their location, repair is difficult, and recurrence is common. Few studies exist to support a standard protocol for repair of these lateral hernias. We hypothesized that anchoring our repair to fixed bony structures would reduce recurrence rates.

METHODS

A retrospective review of all patients who underwent lateral hernia repair at our institution was performed.

RESULTS

Eight cases (seven flank and one thoracoabdominal) were reviewed. The median defect size was 105 cm² (range 36-625 cm²). The median operative time was 185 min (range 133-282 min). There were no major complications. One patient who was repaired without mesh attachment to bony landmarks developed a recurrence at ten months and subsequently underwent reoperation. Patients with mesh secured to bony landmarks were recurrence free at a median follow-up of 171 days.

CONCLUSIONS

Lateral hernias present a greater challenge due to their anatomic location. An open technique with mesh fixation to bony structures is a promising solution to this complex problem.

Parental experiences and perceptions of infant complementary feeding: a qualitative evidence synthesis

BACKGROUND

Interventions to prevent childhood obesity increasingly focus on infant feeding, but demonstrate inconsistent effects. A comprehensive qualitative evidence synthesis is essential to better understand feeding behaviours and inform intervention development. The aim of this study is to synthesize evidence on perceptions and experiences of infant feeding and complementary feeding recommendations.

METHODS

Databases CINAHL, EMBASE, MEDLINE, PsycINFO, Academic Search Complete, SocIndex and Maternity and Infant Care were searched from inception to May 2017. Eligible studies examined parents' experiences of complementary feeding of children (<2 years). Data were synthesized using thematic synthesis.

RESULTS

Twenty-five studies met inclusion criteria for review. Four key themes emerged. 'Guidelines and advice' highlights variety and inconsistencies between sources of complementary feeding information. 'Stage of weaning' describes infant feeding as a process involving different stages. 'Knowing and trying' outlines parents' engagement in feeding approaches based on instinct, prior experience or trial and error. 'Daily life' highlights problematic cost and time constraints for parents.

DISCUSSION

Parents predominantly understand and want to engage in healthy feeding processes. Consideration of infant feeding as a process that changes over time is necessary to support parents. Provision of clear, consistent information and guidance from trusted sources on when, what and how to feed is also essential.

Preventing Rescue Surgeries by Endoscopic Clipping: A Valuable Resource in the Surgeon's Toolbox

AIM

Over-the-scope-clip (OTSC) System is a relatively new endoluminal intervention for gastrointestinal (GI) leaks, fistulas, and bleeding. Here, we present a single center experience with the device over the course of 4 years.

METHODS

Retrospective chart review was conducted for patients who received endoscopic OTSC treatment. Primary outcome is the resolution of the original indication for clip placement. Secondary outcomes are complications and time to resolution.

RESULTS

Forty-one patients underwent treatment with the OTSC system from 2011 to 2015 with average follow-up of 152 days. The average age is 53.7. The most common site of clip placement was in the stomach (44%). Clips were placed after surgical complication for 28 patients (68%), endoscopic complications for 8 patients (19%), and spontaneous presentation in 5 patients (12%). Technical success was achieved in all patients. Overall, 34 patients (83%) were successfully treated. Nine patients required multiple clips and three patients required additional treatment modalities after OTSC. Four patients used the OTSC as a bridging therapy to surgery. Using OTSC for palliation versus nonpalliative indications was associated with lower rates of treatment success (50% versus 86%, P = .028). Using OTSC for symptoms <6 months had higher rates of treatment success than those experiencing longer symptoms (88% versus 65%, P = .045). There were no major morbidities or mortalities directly associated with the OTSC system. Complications from clip use were pain in two patients (5%) and hematemesis in one patient (3%).

CONCLUSIONS

The OTSC System can be a very successful treatment for iatrogenic or spontaneous GI leaks and bleeds. Treatment success is more likely in patients treated within 6 months of diagnosis and less likely to when used for palliation. It was also successfully used as bridging therapy in several patients.

An improved urine collection pad method: a randomised clinical trial

AIM

To evaluate a modified urine collection pad (UCP) method for its ability to reduce heavy mixed growth bacterial contamination of UCP samples in young children with suspected urinary tract infection (UTI).

METHOD

Febrile children under 2 years of age were randomised to two UCP METHODS: the same UCP kept in the nappy until urine was passed (single UCP group), or the UCP replaced with a fresh one every 30 minutes until urine was passed (replaced UCP group). In both groups a moisture sensitive audio alarm was used to signal passage of urine.

RESULTS

Eighty children were enrolled and a satisfactory sample was obtained in 68 (37 in the single UCP group and 31 in the replaced UCP group). In 12 children (15%), collection failed, mainly because of faecal soiling of the pad. UTI occurred in three children (4%). In the remaining 65 samples, heavy mixed growth (> 10(5) organisms/ml) occurred in 1/31 (3%) in the replaced UCP group compared with 10/35 (29%) in the single UCP group (p = 0.008). There were no adverse effects from the use of the moisture sensitive audio alarm.

CONCLUSION

Changing the UCP every 30 minutes almost eliminates heavy mixed growth contamination of UCP samples and substantially increases the proportion of UCP results that confidently exclude UTI. This represents a simple and clinically important improvement to the UCP method which is reliable for diagnosing and excluding UTI in young children still in nappies. It has potential for use in outpatient clinics, in the primary healthcare setting, or at home.

Retrospective analysis of evidence base for tests used in diagnosis and monitoring of disease in respiratory medicine

OBJECTIVES

To determine how many common clinical tests used in a respiratory medicine outpatient clinic are based on high quality evidence.

DESIGN

Retrospective review of case notes. Record of first three tests for each patient. Diagnostic tests, tests used to assess existing condition, explicit trials of therapy were included. Literature search for supporting evidence and grading of best evidence for each test.

SETTING

Inner city university teaching hospital in the United Kingdom.

PARTICIPANTS

All new outpatients referred to a single respiratory medicine team over a period of three months.

MAIN OUTCOME MEASURES

Proportion of tests supported by level 1a-1c evidence (scale developed by Centre for Evidence Based Medicine).

RESULTS

Only half the tests that were used to make or exclude a diagnosis and a fifth of the tests used to assess a known condition were supported by level 1a-1c evidence. There was no evidence to support trials of therapy.

CONCLUSIONS

A large proportion of clinical tests in respiratory medicine are not supported by level 1a-1c evidence. None of the therapeutic trials that were used were supported by evidence.

C-cell and thyroid epithelial tumours and altered follicular development in transgenic mice expressing the long isoform of MEN 2A RET

Gain-of-function mutations in the gene encoding the receptor tyrosine kinase RET have been identified as the aetiological factor for multiple endocrine neoplasia type 2A (MEN2A). MEN2A is a dominantly-inherited cancer predisposition syndrome characterized by medullary thyroid carcinoma, a tumour of the calcitonin-producing thyroid C-cells. There are three isoforms of RET: RET9, RET43 and RET51, and although in vitro evidence suggests they vary in cellular transformation activities, little is known about their function in tumorigenesis in vivo. To address this, we used RET51 cDNA to construct mice in which the most frequent MEN2A mutation, Cys-634-Arg, was expressed under the control of the human calcitonin promoter (CT-2A mice). These mice developed C-cell tumours resembling human MTC and follicular tumours resembling human papillary thyroid carcinoma (PTC) depending on the founder line examined. One founder line developed compound MTC/PTC at low frequency (8%) and pancreatic cystadenocarcinoma. CT-2A mice also displayed a developmental defect in thyroid follicular structure, in which much of the thyroid was occupied by large irregular cystic follicles thought to be derived from the ultimobranchial body, a developmental precursor of the thyroid gland. The CT-2A mice will provide a suitable model to further study the effects of the MEN 2A RET mutation in vivo.

Suppression of anti-CD3-induced interleukin-4 and interleukin-5 release from splenocytes of Mesocestoides corti-infected BALB/c mice by phosphodiesterase 4 inhibitors

We investigated the suppressive effects of rolipram, RP 73401 (piclamilast), and other structurally diverse inhibitors of adenosine 3'5'-cyclic monophosphate (cAMP)-specific phosphodiesterase (PDE4) on anti-CD3-stimulated interleukin (IL)-4 and IL-5 generation by splenocytes from BALB/c mice infected with Mesocestoides (M) corti. RP 73401 (IC40: 0.011 +/- 0.004 microM) was a very potent inhibitor of anti-CD3-induced IL-4 release, being approximately 40-fold more potent than (+/-)-rolipram (IC40: 0.43 +/- 0.09 microM). A maximal inhibition of 60-70% of the response was achieved at the top concentrations of RP 73401 (1 microM) and rolipram (100 microM). These PDE inhibitors also suppressed IL-5 generation over the same concentration ranges, but the maximal suppression achieved was only 30-40%. R-(-)-rolipram (IC40: 0.39 +/- 0.09 microM) was approximately 6-fold more potent than S-(+)- rolipram (IC40: 2.6 +/- 0.95 microM) in inhibiting IL-4 release. A close correlation (r2 = 0.82) was observed between suppression of IL-4 release by PDE inhibitors and inhibition of CTLL cell PDE4, a form against which R-(-)-rolipram displayed relatively weak inhibitory potency. A poorer correlation (r2 = 0.26) was observed between suppression of IL-4 release and affinities of cAMP PDE inhibitors for the high-affinity rolipram binding site in mouse brain membranes. The cGMP-inhibited PDE (PDE3) inhibitor, siguazodan, had little or no effect (IC40 > 100 microM) on anti-CD3-stimulated release of either IL-4 or IL-5 and did not significantly enhance the inhibitory action of RP 73401 on the release of either of these cytokines. Finally, RP 73401 (IC50: 0.41 +/- 0.19 nM) inhibited anti-CD3-stimulated DNA synthesis in splenocyte preparations from M. corti-infected mice and siguazodan (10 microM) had no effect on this response, either alone or in combination with the PDE4 inhibitor. The results show that PDE4 inhibitors suppress the release of Th2 cytokines from anti-CD3-stimulated murine spenocytes and that this effect is correlated with inhibition of a low-affinity PDE4 form.

Pad urine collection for early childhood urinary-tract infection

Urine collected into absorbent pads is commonly contaminated, making this method unreliable for ruling out urinary-tract infection in young children. Bag samples are equally unhelpful, whereas clean-catch samples are least likely to need repeating.

Mutation of the RET proto-oncogene is correlated with RET immunostaining in subpopulations of cells in sporadic medullary thyroid carcinoma

Mutations in the RET proto-oncogene, which encodes a receptor tyrosine kinase, are associated with the pathogenesis of medullary thyroid carcinoma (MTC). Somatic mutations in RET, predominantly at codon 918, and very rarely at codon 883, have been found in a proportion of sporadic MTC. We have previously shown that approximately 80% of sporadic MTCs had at least one subpopulation with a somatic RET mutation. Uneven distribution of somatic mutation within a single tumor or among metastases from a single individual was notable. In the present study, we sought to correlate RET expression, as demonstrated by RET immunohistochemistry, with mutation status in sporadic MTC for each tumor. Seventy evaluable subpopulations, belonging to 28 unrelated sporadic cases, comprising primary MTC and metastases, were immunostained with two different polyclonal antibodies raised against the C-terminus of RET. The regional presence of codon 918 or 883 seemed to coincide with increased RET immunopositivity in at least 62 of 70 (89%, P < 0.000001) tumor subpopulations. The reasons for this concordance are not entirely clear but could be related to either RNA or protein stability. Preliminary studies have suggested that the presence of somatic codon 918 mutation in MTC has a prognostic significance. If these preliminary results prove true, then given our data, we can further explore the feasibility of RET immunocytochemistry as a rapid assessment for the presence of somatic codon 918 for molecular diagnostic and prognostic purposes.

Germline mutation of RET codon 883 in two cases of de novo MEN 2B

Germline mutations in the RET proto-oncogene are seen in the majority of patients with the dominantly inherited cancer syndromes multiple endocrine neoplasia type 2 (MEN 2). The clinical subtypes of MEN 2 (MEN 2A, MEN 2B and familial MTC) all have medullary thyroid carcinoma, but vary in the involvement of pheochromocytoma, parathyroid adenoma/hyperplasia and developmental abnormalities. A single RET mutation, resulting in the substitution M918T, has been identified in 94% of cases of MEN 2B (which consists of MTC, pheochromocytoma and developmental abnormalities). Here we report the identification of a new germline RET mutation (A883F) in two de novo cases of MEN 2B. Identification of this new mutation will contribute to understanding the molecular basis of MEN 2B, and will assist in the clinical management of families harbouring this mutation.

Evidence that cyclic AMP phosphodiesterase inhibitors suppress interleukin-2 release from murine splenocytes by interacting with a 'low-affinity' phosphodiesterase 4 conformer

1. We have investigated the suppressive effects of rolipram, RP 73401 (piclamilast) and other structurally diverse inhibitors of cyclic AMP-specific phosphodiesterase 4 (PDE4) on interleukin (IL)-2 generation from Balb/c mouse splenocytes exposed to the superantigen, Staphylococcocal enterotoxin-A (Staph. A). The purpose was to determine whether their potencies are more closely correlated with inhibition of PDE4 from CTLL cells, against which rolipram displays weak potency (low-affinity PDE4), or displacement of [3H]-(+/-)-rolipram from its high-affinity binding site (HARBS) in mouse brain cytosol. 2. RP 73401 (IC50 0.46 +/- 0.07 nM, n = 4) was a very potent inhibitor of Staph. A-induced IL-2 release from Balb/c mouse splenocytes, being > 1100 fold more potent than (+/-)-rolipram (IC50 540 +/- 67 nM, n = 3). 3. A close correlation (r = 0.95) was observed between suppression of IL-2 release by PDE inhibitors and inhibition of PDE4. In contrast, little correlation (r = 0.39) was observed between suppression of IL-2 release and their affinities for the high-affinity rolipram binding site (HARBS). 4. RP 73401 only inhibited partially (30-40%) Staph. A-induced incorporation of [3H]-thymidine into splenocyte DNA. The PDE3 inhibitor, siguazodan (10 microM), had little or no effect on IL-2 release or DNA synthesis. This concentration of siguazodan did not enhance the inhibitory action of RP 73401 on IL-2 release but potentiated its effect on DNA synthesis, increasing potency and efficacy. 5. Staph. A-induced DNA synthesis was only partially inhibited by anti-IL-2 neutralizing antibody, whereas dexamethazone (100 nM) and cyclosporine A (100 nM) completely blocked the response. 6. RP 73401 (IC50 6.3 +/- 1.9 nM, n = 4) was 140 fold more potent than rolipram (IC50 900 +/- 300 nM, n = 3) in inhibiting Staph. A-induced [3H]-thymidine incorporation into splenocyte DNA. 7. The results implicate a low-affinity form of PDE4 in the suppression of Staph. A-induced IL-2 release from murine splenocytes by PDE inhibitors. The data also indicate that mitogenic factors other than IL-2, whose elaboration or responses to which are regulated by PDE3 as well as PDE4, contribute to the superantigen-induced DNA synthesis.

RET alternate splicing influences the interaction of activated RET with the SH2 and PTB domains of Shc, and the SH2 domain of Grb2

Activating germline mutations of the RET receptor tyrosine kinase are found in the majority of cases of inherited cancer syndrome MEN 2, and inactivating mutations in some cases of dominantly inherited Hirschsprung disease. Using RET activated by a MEN 2 mutation, we show that both the SH2 and PTB domains of the adaptor protein Shc interact with RET, and we identify the PTB domain interaction site. Interaction with both the SH2 and PTB domains of Shc contributes to the transcriptional activation of a serum response element. RET alternate splicing affects the strength of interaction with both the Shc SH2 and PTB domains. In addition, a splice isoform-specific HSCR missense mutation, which does not inactivate the RET kinase activity, decreases the strength of the PTB domain interaction and the level of RET-dependent Shc phosphorylation.

Mutation analysis of the c-mos proto-oncogene and the endothelin-B receptor gene in medullary thyroid carcinoma and phaeochromocytoma

The characteristic tumours of MEN 2 are medullary thyroid carcinoma (MTC) and phaeochromocytoma. Somatic RET mutations have been found in only 23-40% of sporadic MTC and 10% of sporadic phaeochromocytomas. Thus, we sought other genes which may play a role in the pathogenesis of these tumours. We carried out direct sequence analysis of human c-mos and human ENRB in a series of sporadic MTC and phaeochromocytomas to determine if somatic mutations in these two genes could account for some of the sporadic MEN 2-related tumours in which no RET mutations are detected. No somatic mutations were found.

Heterogeneous mutation of the RET proto-oncogene in subpopulations of medullary thyroid carcinoma

Mutations in the RET proto-oncogene are associated with the pathogenesis of medullary thyroid carcinoma (MTC). In an attempt to understand this process, we examined microdissected subpopulations from MTC and multiple metastases from these tumors. Approximately 80% of sporadic MTC's had at least one subpopulation with the RET codon 918 mutation, which is a mutation previously detected in sporadic MTC as a somatic mutation and in multiple endocrine neoplasia type 2B as a germline mutation. However, the distribution of this mutation was nonhomogeneous, occurring only in subpopulations in most tumors and among subsets of multiple metastases, thus implying that although the codon 918 mutation could be an early event, it is not necessarily an early or essential event in tumorigenesis. This heterogeneity suggests either that the codon 918 mutation can arise as an event in progression within a metastatic clone or within a single tumor, or that MTC can be of polyclonal origin. Of significance, one of two multiple endocrine neoplasia type 2A MTCs carried a somatic mutation at codon 918, in addition to the RET mutation present in the germline. We found no correlation between the presence of other somatic genetic events, such as loss of heterozygosity on chromosome arms 1p and 22q, and RET mutation status in the various subpopulations of MTC.

Germline and somatic mutations in an oncogene: RET mutations in inherited medullary thyroid carcinoma

Inherited cancer syndromes predispose an individual to development of specific tumors. Somatic and germline mutations in the same tumor suppressor gene, as described in Knudson's two-mutation model, are well recognized. Inherited mutations in the RET proto-oncogene, which encodes a receptor tyrosine kinase, predispose individuals to the multiple endocrine neoplasia type 2 (MEN 2) cancer syndromes. The major component tumor of these syndromes is medullary thyroid carcinoma (MTC). To date, somatic mutations in RET have not been identified in tumors from individuals with MEN 2, although they have been well documented in sporadic MEN 2-related tumors. We have identified, among 16 MEN 2 cases with well-defined RET germline mutations, a somatic missense mutation at codon 918 of RET in 3 of 15 MTCs and in a sample with hyperplastic C-cells (presumed precursor to hereditary MTC). We suggest that the presence of a somatic mutation, in addition to the preexisting germline mutation in hereditary MTCs, may contribute to tumorigenesis in vivo.

Mutations in the RET proto-oncogene and the von Hippel-Lindau disease tumour suppressor gene in sporadic and syndromic phaeochromocytomas

Phaeochromocytomas may occur sporadically, or as part of the inherited cancer syndromes multiple endocrine neoplasia (MEN) type 2, von Hippel-Lindau disease (VHL), and, rarely, in type 1 neurofibromatosis. In MEN 2, germline missense mutations have been found in one of eight codons within exons 10, 11, 13, 14, and 16 of the RET proto-oncogene. In VHL, germline mutations within one of the three exons are responsible for the majority of cases. To determine if somatic mutations similar to those seen in the germline in MEN 2 or VHL disease play a role in the pathogenesis of sporadic or familial phaeochromocytomas, we analysed 48 sporadic tumours and tumours from 17 MEN 2 and five VHL patients for mutations in RET exons 9, 10, 11, 13, 14, 15, and 16, and the entire coding sequence of VHL. Five of 48 sporadic phaeochromocytomas had RET mutations within exons 10, 11, and 16. Of these, one was proven to be germline and two were proven to be somatic mutations. Four of 48 had VHL mutations; these included both the bilateral cases in the series (one was proven to be a germline mutation) and two others, of which one was proven somatic.

Liberation of sulfate from sulfate esters by soils

When incubated with acid, alkaline, and neutral soils, a variety of synthetic sulfate esters representing the various classes of these compounds was hydrolyzed by enzymes, probably of microbial origin. The appearance of sulfate in the soil water occurred immediately after introduction into the soils with some esters, whereas with others it occurred only after lag periods. Heat treatment destroyed the hydrolytic acitivity in the soils. The ester sulfate groups present in humic acid extracted from the soil appeared to be resistant to hydrolysis by a variety of sulfohydrolases extracted from bacteria and other organisms.

Microbial metabolism of the pyridine ring. The hydroxylation of 4-hydroxypyridine to pyridine-3,4-diol (3,4-dihydroxypyridine) by 4-hydroxypyridine-3-hydroxylase

1. The first metabolic step in the biodegradation of 4-hydroxypyridine by an Agrobacterium sp. was hydroxylation to form pyridine-3,4-diol. 2. Extracts required 1mol of O(2) and 1mol of NADH or NADPH for the conversion of 4-hydroxypyridine into pyridine-3,4-diol, suggesting that the enzyme responsible, 4-hydroxypyridine-3-hydroxylase, was a mixed function mono-oxygenase. 3. After treatment with acidic (NH(4))(2)SO(4) the enzyme required FAD for activity; FMN and riboflavin would not substitute for FAD. 4. The rate of anaerobic reduction of FAD by NAD(P)H was increased more than tenfold in the presence of 4-hydroxypyridine, suggesting that the mechanism of hydroxylation was similar to that of other aromatic hydroxylases which are of the mono-oxygenase type. 5. The partially purified enzyme was extremely specific for its heterocyclic substrate but would utilize either NADH or NADPH. 6. 4-Hydroxypyridine-3-hydroxylase was strongly inhibited by high substrate concentration (above 0.5mm) especially below pH7.5. 8. The inflexion at pH8.4 in a pK(m) versus pH plot, together with strong inhibition by p-chloromercuribenzoate, suggested a role for thiol groups in substrate binding.

Microbial metabolism of the pyridine ring. Metabolism of 2- and 3-hydroxypyridines by the maleamate pathway in Achromobacter sp

1. Washed suspensions of two Achromobacter species (G2 and 2L), capable of growth upon 2- and 3-hydroxypyridine respectively as sources of C and N, rapidly oxidized their growth substrate pyridine-2,5-diol (2,5-dihydroxypyridine) and the putative ring-cleavage product maleamate without a lag. Suspensions derived from fumarate plus (NH(4))(2)SO(4) cultures were unable to do so. 2. Extracts of both bacteria oxidized pyridine-2,5-diol with the stoicheiometry of an oxygenase forming 1mol of NH(3)/mol of substrate. 3. Heat-treated extracts, however, formed maleamate and formate with little free NH(3). 4. The conversion of maleamate into maleate plus NH(3) by extracts of strain 2L, fractionated with (NH(4))(2)SO(4), and the metabolism of maleamate and maleate to fumarate by extracts of both strains demonstrated the existence of the enzymes catalysing each reaction of the maleamate pathway in these bacteria. 5. The pyridine-2,5-diol dioxygenase (mol.wt. approx. 340000) in extracts of these Achromobacter species required Fe(2+) (1.7mum) to restore full activity after dialysis or treatment with chelating agents; the enzyme from strain 2L also had a specific requirement for l-cysteine (6.7mm), which could not be replaced by GSH or dithiothreitol. 6. The oxygenase was strongly inhibited in a competitive manner by the isomeric pyridine-2,3- and -3,4-diols.

Microbial metabolism of the pyridine ring. The metabolism of pyridine-3,4-diol (3,4-dihydroxypyridine) by Agrobacterium sp

1. Pyridine-3,4-diol (3,4-dihydroxypyridine, 3-hydroxypyrid-4-one), an intermediate in 4-hydroxypyridine metabolism by an Agrobacterium sp (N.C.I.B. 10413), was converted by extracts into 1mol of pyruvate, 2mol of formate and 1mol of NH(3) at pH7.0. 2. Formate, but not the alternative likely product formamide, was further oxidized fivefold faster by 4-hydroxypyridine-grown washed cells than by similar organisms grown on succinate. 3. The oxidation of pyridine-3,4-diol by crude extracts at pH8.5 required 1mol of O(2)/mol of substrate, produced 1mol of acid and led to the formation of formate and a new compound with an extinction maximum of 285nm (Compound I). This step was believed to be mediated by a new labile dioxygenase (t((1/2))=4h at pH7.0, 4 degrees C) cleaving the pyridine ring between C-2 and C-3. 4. Many of the properties of this pyridine-3,4-diol dioxygenase paralleled those of the extradiol (;meta') oxygenases of aromatic-ring cleavage. The extreme lability of the enzyme has so far precluded extensive purification. 5. Compound I showed changes in the u.v.-absorption spectrum with pH but after acidification it was converted into a new product, 3-formylpyruvate, with an extinction maximum now at 279nm. 6. Both Compound I and 3-formylpyruvate were metabolized by extracts but at very different rates. The slower rate of metabolism of Compound I was nevertheless consistent with that of pyridine-3,4-diol metabolism. 7. On acidification Compound I released about 0.65mol of NH(3) and has been identified as 3-formiminopyruvate. 8. 3-Formylpyruvate was hydrolysed to formate and pyruvate (K(m) 2mum) by an acylpyruvate hydrolase active against several other dioxo homologues. The activity of this enzyme was much lower in extracts of succinate-grown cells.

Microbial metabolism of the pyridine ring. Formation of pyridinediols (dihydroxypyridines) as intermediates in the degradation of pyridine compounds by micro-organisms

1. Several species of micro-organisms that were capable of utilizing pyridine compounds as carbon and energy source were isolated from soil and sewage. Compounds degraded included pyridine and the three isomeric hydroxypyridines. 2. Suitable modifications of the cultural conditions led to the accumulation of pyridinediols (dihydroxypyridines), which were isolated and characterized. 3. Three species of Achromobacter produced pyridine-2,5-diol from 2- or 3-hydroxypyridine whereas an uncommon Agrobacterium sp. (N.C.I.B. 10413) produced pyridine-3,4-diol from 4-hydroxypyridine. 4. On the basis of chemical isolation, induction of the necessary enzymes in washed suspensions and the substrate specificity exhibited by the isolated bacteria, the initial transformations proposed are: 2-hydroxypyridine --> pyridine-2,5-diol; 3-hydroxypyridine --> pyridine-2,5-diol and 4-hydroxypyridine --> pyridine-3,4-diol. 5. A selected pyridine-utilizer, Nocardia Z1, did not produce any detectable hydroxy derivative from pyridine, but carried out a slow oxidation of 3-hydroxypyridine to pyridine-2,3-diol and pyridine-3,4-diol. These diols were not further metabolized. 6. Addition of the isomeric hydroxypyridines to a model hydroxylating system resulted in the formation of those diols predicted by theory.