The missing large impact craters on Ceres.

Asteroids provide fundamental clues to the formation and evolution of planetesimals. Collisional models based on the depletion of the primordial main belt of asteroids predict 10-15 craters >400 km should have formed on Ceres, the largest object between Mars and Jupiter, over the last 4.55 Gyr. Likewise, an extrapolation from the asteroid Vesta would require at least 6-7 such basins. However, Ceres' surface appears devoid of impact craters >∼280 km. Here, we show a significant depletion of cerean craters down to 100-150 km in diameter. The overall scarcity of recognizable large craters is incompatible with collisional models, even in the case of a late implantation of Ceres in the main belt, a possibility raised by the presence of ammoniated phyllosilicates. Our results indicate that a significant population of large craters has been obliterated, implying that long-wavelength topography viscously relaxed or that Ceres experienced protracted widespread resurfacing.

Enteral tube feeding in adults.

Enteral tube feeding is usually a relatively straightforward method of nutritional support, and should be facilitated by a multiprofessional team. For short-term use (<4 weeks) a fine bore feeding nasogastric tube is indicated but if longer term feeding is required then a gastrostomy is appropriate, usually inserted endoscopically (a percutaneous endoscopic gastrostomy tube). The most common serious complication of a nasogastric tube is not identifying a misplaced tube within the lungs: there are clear recommendations from the National Patient Safety Agency as to how to check tube placement. Nasojejunal tubes are required in patients with gastroparesis. Tube blockage is common and is prevented by careful and regular flushing. Diarrhoea is the most complication of feeding and is often related to other medication. Clinicians need an algorithm for systematically dealing with such a problem. Refeeding syndrome may occur in malnourished patients and is characterised by low levels of potassium, phosphate, and/or magnesium, as well as disorders of water and salt balance. Identifying the at-risk patient with careful monitoring is crucial.

Diarrhoea in the enterally fed patient.

Diarrhoea complicating enteral feeding is very common in all clinical settings. The major risk factor is the use of concomitant antibiotics. The underlying mechanisms for the diarrhoea mainly relate to alterations in the colonic flora and physiological responses to the mode of feed delivery although a clear understanding of what is actually happening in vivo remains elusive. Management of diarrhoea includes rationalising medications, excluding relevant comorbidity and using antidiarrhoeal medications. Altering the method and site of feed delivery-for example, continuous to bolus, gastric to postpyloric-can also be tried in the more difficult cases.

Muscle cramps are the commonest side effect of home parenteral nutrition.

BACKGROUND & AIMS: Complications resulting from home parenteral nutrition (HPN) reduce a patient's quality of life. The major complications of catheter-related sepsis, venous thrombosis and chronic liver disease are well recognised. This study aimed to determine if there were other minor, but common complications that caused patient distress. METHODS: All patients (45) from four HPN centres were asked if they had suffered any side effects of parenteral nutrition and whether these side effects related to the timings of the feed or required specific intervention. RESULTS: Muscle cramps were the most common minor side effect [12/45 (27%)]. A greater proportion of HPN patients (51%) suffered from muscle cramps than did a control group of patients with inflammatory bowel disease (24%) [p=0.0001]. In the HPN patients, no significant difference in serum electrolyte concentration or in feed composition was noted between those patients with and those without cramps in relation to feeds. Cramps were of sufficient severity to warrant pharmacological intervention in 9 of 12 patients who had cramps in relation to feeds, and parenteral nutrition administration was slowed in 2 of the 12. CONCLUSION: Muscle cramps have a high prevalence in patients receiving home parenteral nutrition.

Enteral nutrition.

Enteral nutrition is feeding the gastrointestinal tract either with food, oral supplements or via tube. It is generally safe, easy to administer and free of major complications. The most common problems relate to the tubes themselves, such as blockage and stoma infection.

Randomized clinical trial of the effects of preoperative and postoperative oral nutritional supplements on clinical course and cost of care.

BACKGROUND: Postoperative oral nutritional supplementation has been shown to be of clinical benefit. This study examined the clinical effects and cost of administration of oral supplements both before and after surgery. METHODS: This was a randomized clinical trial conducted in three centres. Patients undergoing lower gastrointestinal tract surgery were randomized to one of four groups: group CC received no nutritional supplements, group SS took supplements both before and after surgery, group CS received postoperative supplements only, and group SC were given supplements only before surgery. Preoperative supplements were given from the time it was decided to operate to 1 day before surgery. Postoperative supplements were started when the patient was able to take free fluids and continued for 4 weeks after discharge from hospital. Data collected included weight change, complications, length of stay, nutritional intake, anthropometrics, quality of life and detailed costings covering all aspects of care. RESULTS: Some 179 patients were randomized, of whom 27 were withdrawn and 152 analysed (CC 44, SS 32, CS 35, SC 41). Dietary intake was similar in all four groups throughout the study. Mean energy intake from preoperative supplements was 536 and 542 kcal/day in the SS and SC groups respectively; that 2 weeks after discharge from hospital was 274 and 361 kcal/day in the SS and CS groups respectively. There was significantly less postoperative weight loss in the SS group than in the CC and CS groups (P < 0.050), and significantly fewer minor complications in the SS and CS groups than the CC group (P < 0.050). There were no differences in the rate of major complications, anthropometrics and quality of life. Mean overall costs were greatest in the CC group, although differences between groups were not significant. CONCLUSION: Perioperative oral nutritional supplementation started before hospital admission for lower gastrointestinal tract surgery significantly diminished the degree of weight loss and incidence of minor complications, and was cost-effective.

Distal colonic motor activity in four subgroups of patients with irritable bowel syndrome.

With the aim of improving end organ treatment, we describe a new system of classifying irritable bowel syndrome (IBS) according to clinical features into four groups, spastic colon syndrome (SCS), functional diarrhea (FD), diarrhea-predominant spastic colon syndrome (DPSCS), and midgut dysmotility (MGD). The aim of the study was to investigate fasting and postprandial distal colonic motility in the four groups of patients and to compare the results with normal controls. Distal colonic motility studies were performed in the unprepared colon. 2.5-hr recordings were made from four channels with a standard meal administered at 0.5 hr. The intubated colon was treated as a study segment and data analyzed for study segment activity index (SSAI) and number and mean amplitude of pressure peaks over 30-min epochs. Patients with SCS had significantly higher (P < 0.05) mean amplitude of pressure peaks (60 min, 120 min) and SSAI (120 min) than controls and patients with FD, DPSCS, and MGD. In contrast, patients with FD and DPSCS had significantly (P < 0.05) lower postprandial SSAI than controls and patients with SCS (60 min, 120 min). With the exception of raised postprandial mean amplitude of pressure peaks (120 min), MGD patients had normal distal colonic motility. Division of IBS patients into subgroups has highlighted significant differences in distal colonic motility that provide insights into etiopathogenesis and should assist targeting of current and newly developed therapies, particularly receptor active agents.

Neurofibromatosis associated with a coronary artery aneurysm.

A case of a patient with type 1 neurofibromatosis associated with popliteal and coronary artery aneurysms is described in which cross-sectional imaging provided diagnostic information.

Drinking before endoscopy: milk or water?

BACKGROUND: The traditional fluid fast prior to endoscopy is unnecessary. We have previously shown that drinking water prior to endoscopy does not affect either the quality of mucosal views or residual gastric fluid volumes when compared to patients undergoing endoscopy after a standard fast. The present study was designed to establish whether milk, which may delay gastric emptying, could also be drunk prior to endoscopy without adverse effect. METHODS: Forty-eight patients (mean age 48 years, range 20 to 79) undergoing routine upper gastrointestinal endoscopy after overnight fast were randomized to drink 200 ml of either still mineral water or full fat milk. Endoscopy was performed 90 minutes later, when all residual gastric fluid was aspirated via the endoscope. Volume and pH of gastric aspirate were measured and the quality of the mucosal view at endoscopy recorded as poor, adequate, or excellent. RESULTS: No difference was shown between water (n = 27) and milk (n = 21) drinkers in residual gastric volume (mean +/- SEM, water vs milk) (16.0 ml +/- 1.5 vs 18.9 ml +/- 2.9) or pH (2.23 +/- 0.14 vs 2.48 +/- 0.14). Of those patients with poor, adequate, or excellent views, 4 of 4, 11 of 12, and 6 of 32 patients, respectively, were milk drinkers (chi-squared test for trend = 21.7, df = 1, p < 0.001), indicating significantly worse mucosal views in the group drinking milk. CONCLUSION: Drinking water up to 90 minutes prior to endoscopy is safe, but milk should be discouraged because of suboptimal mucosal views.

Hormonal response to enteral feeding and the possible role of peptide YY in pathogenesis of enteral feeding-related diarrhoea.

Diarrhoea is a common complication of enteral feeding. Previous studies have demonstrated a secretion of water and electrolytes in the ascending colon during intragastric but not intraduodenal enteral feeding. The cause of this secretion is likely to be neurohumoral in origin. This study was designed to examine the hormonal responses to enteral feeding. In vivo segmental colonic perfusion studies were undertaken. Before and at hourly intervals during these studies serum was taken for estimations of neurotensin (NT), pancreatic glucagon (PG), peptide YY (PYY) and vasoactive intestinal polypeptide (VIP). During fasting there was a median ascending colonic absorption of water in all groups. During feeding there was a net secretion in the ascending colon in both gastric groups and in the high load duodenal group, but not in the low load duodenal group. During these studies the PYY levels remained unchanged from fasting in the low and high load gastric groups. In the low and high load duodenal groups the PYY levels increased. The NT levels increased only in the high load duodenal group. There were no other changes in NT or in PG or VIP levels either between fasting and feeding, or between the gastric and duodenal groups. PYY is known to stimulate intestinal absorption. The absence of a rise during intragastric feeding may be important in the underlying mechanisms of enteral feeding-induced colonic secretion and hence enteral feeding-related diarrhoea.

Prospective randomized comparison of two different sized percutaneous endoscopically placed gastrostomy tubes.

We performed a prospective randomised study of two different sized percutaneous endoscopic gastrostomy (PEG) tubes to determine if tube size influenced the incidence of PEG-related complications. Patients were given prophylactic cefuroxime, if not already on antibiotics at the time of PEG insertion. Fifty-two PEGs were successfully placed, 26 in each group. Most patients who required a PEG had suffered a cerebrovascular event (82.7%). There were no procedure-related deaths. The mean ages (standard deviation) for the 12 and 20 French Gauge (FG) groups were 78.7 (8.9) and 73.9 (14.4) years, respectively, with no statistical difference. There were no significant differences in mortality (9 deaths in the 12 FG and 11 deaths in the 20 FG groups), number of peristomal infections (8 infections in the 12 FG and 12 infections in the 20 FG groups), episodes of leakage (12 leakages in the 12 FG and 17 leakages in the 20 FG groups) or tube blockage (2 blockage episodes in the 12 FG and 1 blockage episode in the 20 FG groups) between the two groups over a follow-up period of 190 days. The incidence of insertion- and feeding-related complications was thus not influenced by tube size. As the smaller PEG tubes were easier and less traumatic to insert we conclude that there are grounds for considering the more widespread use of the narrower diameter 12 FG PEG tubes.

A retrospective comparison of endoscopic stenting alone with stenting and radiotherapy in non-resectable cholangiocarcinoma.

BACKGROUND AND AIMS: Radiotherapy has been reported to be of benefit in prolonging the survival of patients with cholangiocarcinoma. This study examined whether radiotherapy in addition to endoscopic stenting improved survival. SUBJECTS: 56 patients with obstructive jaundice due to histologically confirmed non-resectable cholangiocarcinoma. METHODS: A retrospective analysis of these patients who were treated either with endoscopic biliary stenting followed by external beam radiotherapy and internal iridium-192 brachytherapy (n = 28) or with stenting alone (control group; n = 28). RESULTS: The two groups were well matched in age, sex, and stricture type. Eighteen patients had a type I stricture (control group: 11; radiotherapy group: 7) at the time of diagnosis and 38 had a type II or III stricture (control group: 17; radiotherapy group: 21). The median (range) overall survival from diagnosis was seven (1-29) and 10 (4-75) months in the control and radiotherapy groups respectively: This difference did not reach statistical significance (p = 0.06), but survival plots indicated a survival advantage in the radiotherapy group in the first nine months after diagnosis. Approximately one third survived longer than one year in both groups. More patients in the radiotherapy group required a stent change (1.9 v 0.9: p = 0.05), and also had a longer overall inpatient stay (42 days v 19: p < 0.001). When examined on the basis of stricture type, there was a survival advantage in the first 10 months after diagnosis in those with a type II/III stricture (seven and 11 months in the radiotherapy and control groups respectively: 0.01 < p < 0.05). There was no difference in survival between the groups in those with a type I stricture. Numbers surviving longer than one year, stent survival, and number of stent changes were all similar between the two groups when examined on the basis of stricture type, but length of hospital stay remained considerably longer in all patients receiving radiotherapy. CONCLUSION: The survival advantage of radiotherapy in those with a type II/III stricture is seen only in the first 10 months after diagnosis. The costs of radiotherapy and significantly increased time spent in hospital, however, raise doubts over its routine use in the management of non-resectable cholangiocarcinoma.

Interchange between collagenous and lymphocytic colitis in severe disease with autoimmune associations requiring colectomy: a case report.

BACKGROUND: Collagenous colitis and lymphocytic colitis present with a similar clinical picture. Whether these conditions are separate entities or whether they represent different pathological stages of the same condition is an unresolved issue. PATIENT: This is a case of collagenous colitis following a fulminant course in which a colectomy was necessary. In the operative specimen the thickened collagen plate, which had been present only two weeks preoperatively had been lost and the pathology was of a lymphocytic colitis. Six months postoperatively this patient developed a CREST syndrome and primary biliary cirrhosis. CONCLUSIONS: This case shows the lability of the collagen plate and the common ground between collagenous and lymphocytic colitis, and presents evidence that these two conditions are different manifestations of the same disease. It also describes for the first time an association between collagenous colitis and CREST syndrome and primary biliary cirrhosis.

How long does it take to operate? The implications for in patient malnutrition.

The development of in-patient malnutrition often begins long before hospital admission. The aim of this retrospective study was to assess the time period taken from when patients first present to their General Practitioners to surgery. Patients undergoing elective intraabdominal surgery over a 3 month period in a district general hospital were divided into two groups: One for those with underlying gastrointestinal malignancy requiring resection (n = 27), and the other in those with chronic biliary disease requiring laparoscopic cholecystectomy (n = 24). Patients with malignant disease presented to the GP at a mean of 3.0 months (SD 2.4) after symptom onset, and those with biliary disease at 3.5 months (SD 2.6). Those with malignancy were then referred and seen by the hospital within a mean of 2.8 weeks (SD 1.3), investigated in 3.3 weeks (SD 2.3) and operated on within 2.7 weeks (SD 1.2). The group with biliary disease were seen in hospital at 6.2 weeks (SD 1.9), investigated in 7.5 weeks (5.8) and operated on at 7.6 weeks (SD 2.1). Overall, the length of time it took from symptom onset to surgery in those with malignant disease was 26 weeks (SD 19), and in those with biliary disease 65 weeks (SD 35). This time period will inevitably lead many patients to become malnourished prior to admission, and this may have implications on the incidence of complications and length of in-patient stay.