Composite abdominosacral resection for recurrent rectal cancer

BACKGROUND

En bloc resection of the tumour and adjacent involved organs offers the only realistic curative option for patients with locally recurrent rectal cancer. This study assessed outcomes of composite resection for recurrent tumours involving the sacrum.

METHODS

A consecutive series of patients underwent composite abdominosacral resection (abdominal mobilization and stoma construction followed by sacral division and tumour retrieval) for recurrent rectal cancer between 2001 and 2007. Patients were staged with preoperative computed tomography, magnetic resonance imaging and positron emission tomography. Data were collected prospectively.

RESULTS

Forty patients (28 men; median age 59 (range 31-77) years) underwent surgery with sacral division at the S2/3 interface in 13, S3/4 level in 20 and S4/5 level in seven patients. One patient died and 24 had complications. An R0 resection was achieved in 20 patients and conferred benefit in disease-free interval over an R1 resection. The mean disease-free interval was 55.6 (95 per cent confidence interval (c.i.) 40.0 to 71.3) months for R0 and 32.2 (95 per cent c.i. 19.7 to 44.7) months for R1 resection (P = 0.048).

CONCLUSION

Composite abdominosacral resection of locally recurrent rectal cancer is an effective treatment for a difficult clinical scenario.

Algorithms for the surgical management of retrorectal tumours

BACKGROUND

Retrorectal tumours are uncommon and may present a surgical challenge. The aim of this study was to identify a surgical strategy based on information gained from the multidisciplinary management of retrorectal tumours.

METHODS

This was a retrospective review of 27 patients who had resection of retrorectal tumours between 1998 and 2006.

RESULTS

The tumours included ten cystic lesions, two mature teratomas, four chordomas, seven neurogenic tumours, two sarcomas, one angiomyxoma and one gastrointestinal stromal tumour. The diagnosis was suggested initially by non-specific clinical presentation and palpation of a retrorectal mass on examination (16 patients), pelvic imaging (six), obstructed labour (one), recurrent pilonidal sinus (one), recurrent perianal sepsis (one) and return of symptoms after resection (two). Magnetic resonance imaging (MRI) confirmed the diagnosis and enabled surgical planning. The operative approach was perineal (12 patients), abdominal (11) or combined (four). Factors that influenced the operative approach were tumour position, its neoplastic nature, involvement of the pelvic sidewall or pelvic viscera, and size. The retrorectal tumour recurred in three patients.

CONCLUSION

A successful multidisciplinary surgical strategy, based on preoperative localization by MRI, has been developed for the treatment of retrorectal tumours.

An unusual case of ureteric obstruction

We report a case of a 33-year-old female presenting with right sided abdominal pain, a right iliac fossa mass and right hydronephrosis. The mass was subsequently shown to represent an isolated desmoid tumour compromising the adjacent ureter. The patient had no predisposing factors for this pathology. This is an uncommon occurrence and we discuss the imaging features and differential diagnosis.

MRI assessment of the bony pelvis may help predict resectability of rectal cancer

OBJECTIVE

The outcome after surgical treatment of rectal cancer may be influenced by the technical difficulty of the operation, which is thought to be affected by pelvic size. The aim of this study was to examine the association between bony pelvic dimensions and CRM involvement.

PATIENTS AND METHODS

All patients with primary rectal cancer between December 1999 and January 2002 were studied. Staging was performed by pelvic MRI. Nine pelvic dimensions were measured from the MR images on a workstation. Pathology reports were obtained for all patients and the mesorectal specimen was examined. Technical difficulty was assessed by circumferential resection margin (CRM) involvement.

RESULTS

Of 126 patients with primary rectal cancer, 88 had staging MRI and rectal excision; there were significant differences between the sexes in all 9 pelvic dimensions (P < 0.05). In females, the interspinous diameter was significantly shorter in patients with CRM involvement compared with patients with a negative CRM. In female patients predicted to have a negative CRM, the anteroposterior diameter of the inlet, the anteroposterior diameter of the midplane and the transverse diameter of the midplane (interspinous distance) were significantly shorter in patients who actually had a positive CRM compared with those in whom the CRM was negative. In male patients, there was no correlation between pelvic dimensions and CRM status.

CONCLUSIONS

In certain patients with rectal cancer, CRM positivity may be predicted from pre-operative MRI pelvic measurements. This may influence the choice of adjuvant therapy.

Evaluation of the role of pre-operative magnetic resonance imaging in the management of rectal cancer

OBJECTIVES

This study assesses the ability of body coil magnetic resonance imaging (MRI) to pre-operatively stage mural penetration, nodal status and circumferential resection margin (CRM) involvement of rectal cancer.

PATIENTS AND METHODS

Between 1995 and 1997, MRI using a body coil was performed in consecutive patients with primary rectal carcinomas. Group A: 67 patients underwent surgery without long course neo-adjuvant therapy. Predicted tumour stage was compared to the histology of the specimen. Group B: 21 patients with MRI evidence of advanced disease, underwent long course neo-adjuvant therapy followed by repeat MRI prior to surgery. The second scan assessed response to treatment and likelihood of CRM involvement at subsequent surgery.

RESULTS

Group A: Accuracy of pre-operative staging was: 'T' stage - 54%, 'N' stage - 77%, involvement of CRM by tumour - 97%. Group B: After long course neo-adjuvant therapy the second MRI scan was 95% accurate in predicting CRM involvement by tumour.

CONCLUSION

In this study pre-operative rectal cancer staging with MRI and a body coil lacks accuracy in predicting mural penetration and nodal involvement. Body coil MRI can accurately predict the potential for CRM involvement. This technique may help determine which patients require long course neo-adjuvant therapy.

Renal metastases from a squamous cell carcinoma of the larynx

Laryngeal squamous cell carcinoma (SCC) tends to exhibit local spread with a low incidence of distal metastases. The majority of distal metastases are to the lungs and renal involvement is extremely rare. We present a case of laryngeal SCC with metastatic spread to the left kidney presenting as a large, mainly cystic mass. The radiological differentiation of renal metastases from primary renal tumours is discussed.

Breast metastasis from non-small cell lung cancer

Breast is an unusual site for metastatic disease, particularly for non-small cell lung cancer. We report an unusual case of metastatic breast lesions from a primary anaplastic lung tumor and discuss the common and uncommon sites of metastasis from lung carcinomas.

Spiral computed tomography and operative staging of gastric carcinoma: a comparison with histopathological staging

BACKGROUND

Much controversy exists as to the value of computed tomography (CT) in the preoperative staging of gastric cancer, because of its limited ability to identify correctly lymph node (LN) metastases, invasion of adjacent organs, or hepatic and peritoneal metastases. Spiral CT scanners have a number of potential advantages over conventional scanners, including the absence of respiratory misregistration, image reconstruction smaller than scan collimation permitting overlapping slices and optimisation of intravenous contrast enhancement.

AIM

To compare the performance of spiral CT and operative assessment against formal (TNM) pathological staging.

PATIENTS AND METHODS

A study of 105 consecutive patients who underwent both spiral CT and operative staging was performed. All CT scans were reviewed by a radiologist who commented on tumour location and size, evidence of adjacent organ invasion, lymph node metastases to both N1 and N2 nodes, and evidence of hepatic and peritoneal metastases. All patients underwent careful operative assessment at the time of surgery, along the lines suggested by Rohde and colleagues.

RESULTS

Spiral CT remained poor at identifying LN metastases to both N1 and N2 lymph nodes, with sensitivity ranging from 24 to 43%; specificity, however, was 100%. Operative staging was superior, with sensitivities between 84 and 94%, but specificity was much lower (63-74%). Spiral CT correctly detected 13 of 17 cases of invasion of either the colon or the mesocolon (sensitivity 76%) compared with 16 of 17 cases at operative staging (sensitivity 94%). Spiral CT correctly identified three of six cases with invasion of the pancreas (sensitivity 50%) compared with six of six cases on operative staging (sensitivity 100%). Spiral CT correctly identified 12 of 17 cases of peritoneal metastases (sensitivity 71%) and four of seven cases of hepatic metastases (sensitivity 57%).

CONCLUSION

Whilst spiral CT remains poor at identifying lymph node metastases, it correctly identified most cases with invasion of either the colon or the mesocolon and half the cases of pancreatic invasion. It was of value in detecting peritoneal metastases and some cases with hepatic metastases. At present, at Leeds General Infirmary spiral CT is performed routinely on all patients with gastric cancer and a selective staging laparoscopy policy is adopted in those patients in whom the status of the peritoneal cavity and liver is in doubt.

Imaging appearances of ileouterine fistula complicating recurrent adenocarcinoma of the rectum

Enterouterine fistulae are rare and nowadays are most commonly due to pelvic tumours. We review the literature and present the case of a woman who presented with an ileouterine fistula following surgery and radiotherapy for recurrent rectal adenocarcinoma. The presence of tumour within the fistula track may also have been a significant aetiological factor. Magnetic resonance imaging (MRI) is an excellent method to demonstrate the site and size of the track and has not, to date, been used to identify such a fistula.

The role of imaging in acute pancreatitis

The roles of ultrasound, computed tomography and magnetic resonance in the evaluation and management of acute pancreatitis are discussed with emphasis on the advantages and disadvantages of each. The importance of imaging in the diagnosis of pancreatic necrosis, acute fluid collections, pancreatic abscess, pseudocysts and vascular complications is reviewed. The use of interventional techniques as opposed to surgical intervention is discussed.

T2-weighted and dynamic enhanced MRI in acute pancreatitis: comparison with contrast enhanced CT

The purpose of this study was to compare T2-weighted and dynamic contrast enhanced MRI with contrast enhanced CT in patients with severe acute pancreatitis. Thirty-two patients were examined using axial T2-weighted spin-echo imaging (TR 1801, TE 15/90) and a multi-slice rapid gradient-echo sequence (TR 135, TE 4, FA 80 degrees) (FLASH) in axial and coronal planes. Fifteen 5 mm axial slices at 10 mm intervals were acquired during a single breath-hold of 19 s before, and at 10 and 40 s after a bolus injection of Gd-DTPA. Additional FLASH images in the coronal plane were obtained 2 min after injection of contrast medium. MR was compared with contemporary enhanced CT by two blinded observers who scored pancreatic viability and the content of intra and extra-pancreatic fluid collections. The presence of gas, calcification and haemorrhage was noted. Abnormalities in adjacent organs, evidence of vascular occlusion and indicators of aetiology were also recorded. MR and CT were concordant in distinguishing viable pancreatic tissue from areas of necrosis. MR appeared to be more effective than CT in characterizing the content of fluid collections and in demonstrating gall stones, although CT remains superior in detecting flecks of gas and calcification. MR carries some advantages over CT and can be regarded as an alternative primary technique in patients with severe pancreatitis.

Pseudothrombosis of the infra-renal inferior vena cava during helical CT

Pseudothrombosis of the infra-renal vena cava is a frequent finding during post-contrast helical computed tomography (CT) studies of the abdomen. Three hundred consecutive patients undergoing contrast-enhanced helical studies were evaluated prospectively to document the incidence of pseudothrombosis. Typical CT findings are illustrated and a significant difference in incidence between the male and female population noted.

The radiological treatment of hepatic artery aneurysms

Improvements in the quality and availability of cross-sectional imaging should result in more frequent detection of hepatic artery aneurysms before rupture. Interventional radiological treatment for extra-hepatic lesions has not previously been discussed in the literature. We present two cases of extra-hepatic hepatic artery aneurysms treated using different endovascular techniques and discuss the relative merits of these approaches.

Case report: the demonstration of aortocaval fistulae by helical computed tomography

We report the helical computed tomography findings in two patients with spontaneous aortocaval fistula (ACF) complicating abdominal aortic aneurysm. The use of overlapping slices produced high quality multiplanar reformats which provided anatomical information about the likely site of the ACF and also the relationship of the renal arteries to the neck of the aneurysm.

The role of immediate cytological evaluation in CT-guided biopsy

A prospective study of 130 fine-needle aspiration biopsies (FNAB) was performed on 110 consecutive patients to assess the contribution of immediate cytological evaluation (ICE). All biopsies were performed under CT guidance using either 20 gauge or 22 gauge aspiration needles. Two distinct patient groups were derived from two hospitals. In one hospital a consultant cytologist was usually present, whereas in the other immediate cytological evaluation was not generally available. Overall, a consultant cytologist was present for 52% of the biopsies. The accuracy of the procedure, the number of needle passes made, the complication rates with and without ICE were assessed for each hospital population group. The overall accuracy, with and without ICE, was 72%. Although slightly fewer specimens were deemed inadequate when ICE was available, this difference did not reach statistical significance.

Longitudinal stress fractures of the tibia: MRI features in two cases

Longitudinal stress fractures of the tibia are a recognized but unusual finding in long distance runners. Two cases are presented in which the diagnosis on plain films and scintigraphy (in one case) was not evident. Both patients were referred for MRI. Coronal short tau inversion recovery (STIR) sequences demonstrated extensive hyperintense longitudinal intramedullary signal changes in the tibia. T1-weighted spin-echo scans showed corresponding but less extensive regions of reduced signal intensity. In one case, enhancement of this area was seen following i.v. dimeglumine-gadopentetate (Gd-DTPA). Adjacent soft-tissue abnormality and periosteal reaction was seen in one case but in neither patient was a fracture line identified. Thin section CT with sagittal reformats demonstrated an irregular intracortical longitudinal lucent fracture line which was distinct from the nutrient foramen, establishing the diagnosis.

Dynamic MRI of the pancreas--gadolinium enhancement in normal tissue

The purpose of this study was to measure signal enhancement over time in the normal pancreas after intravenous bolus infection of gadolinium-DTPA (Schering Health Care Ltd) (Gd-DTPA). Data was obtained from 25 patients with no evidence of pancreatic disease before, immediately after and over a 2 min period following injection of Gd-DTPA (Magnevist 0.2 ml per kg). Scans were obtained using a turboFLASH sequence which allows 11 slices to be acquired during a single breathhold period of 19 s. Five mm thick slices were acquired in the coronal/oblique plane at 0.5 mm intervals. A pre-contrast block of slices was obtained followed by dynamic post-contrast scanning with the first of four acquisitions beginning 12-15 s after bolus injection. A 10 s interval between each acquisition was selected to allow the patients to breathe. Signal intensity for each acquisition was measured for the pancreatic head and tail and also for the liver. All values were normalized to fat. Marked enhancement of the pancreas was seen in all cases with peak enhancement occurring in the first and second post-contrast acquisition. The pancreatic duct was more easily seen after contrast injection.

Comparison of MR and CT scanning in severe acute pancreatitis: initial experiences

Magnetic resonance imaging was performed at 1.0 T in seven patients with severe acute pancreatitis. A T2-weighted spin echo sequence and a breath-hold multislice rapid gradient echo sequence (TurboFLASH) were used in each patient. TurboFLASH imaging was performed before and after intravenous gadopentetate-dimeglumine (Gd-DTPA). All MRI images were compared with a recent contrast-enhanced CT scan. Postgadolinium MRI was equivalent to contrast-enhanced CT in differentiating viable pancreatic parenchyma from areas of pancreatic necrosis. MRI identified the presence of gas in a case of pancreatic abscess but failed to identify small foci of pancreatic calcification demonstrated in one case by CT. MRI was also equivalent to CT in assessing the location and extent of peripancreatic inflammatory changes and fluid collections. However, MRI, particularly the T2-weighted spin echo, was superior to CT in characterizing the complex nature of such inflammatory changes in one case. Initial experience suggests that MRI is a valuable technique in assessing patients with severe acute pancreatitis.

Case report: CT demonstration of extravasated contrast medium from traumatic rupture of the gastric artery

We present a case where CT demonstrated intraperitoneal contrast medium subsequently shown to be due to active haemorrhage from a ruptured gastric artery. The appearances may be mistaken for traumatic bowel perforation and the differential is discussed.

Rapid dynamic contrast-enhanced magnetic resonance imaging of the liver and portal vein

The purpose of this study was firstly to show the diagnostic value of a rapid acquisition multislice sequence (TurboFLASH) during bolus injection of gadolinium-DTPA by comparing it with the pulse sequences currently used for abdominal studies and secondly to develop improved scanning protocols for the liver. Patients were referred for upper abdominal studies including portal vein assessment. 40 patients were imaged in the coronal plane using a multislice TurboFLASH (TF) sequence (TR = 100; TE = 4) acquired during a breath-hold period of 19 s. The short echo time allows up to 11 slices of 5 mm thickness to be acquired simultaneously. Images were obtained before, during and after bolus administration of Gd-DTPA. The slices from each acquisition were combined using a maximum intensity projection algorithm to include all the vessels on a single image. Initially each patient was scanned using a conventional axial T2 weighted spin-echo sequence (T2W-SE) (TR2000; TE = 45/90) and a coronal T1 weighted spin-echo sequence (TR450; TE = 15). The clarity of the demonstration of vascular anatomy was compared and scored for all sequences by two radiologists. Vessel patency, the conspicuity of mass lesions and the spread of tumour to adjacent structures were also scored. The anatomy of the main portal vein was significantly better shown by coronal TF images after bolus injection than on T2W-SE images or TF before Gd-DTPA. The right and left portal veins were equally well shown by coronal TF with Gd-DTPA and T2W-SE images. There was no significant difference between contrast enhanced TF and T2W-SE imaging in visualization of the hepatic veins. More lesions were demonstrated by post-contrast TF than by T2W-SE imaging. Portal venous occlusion was better appreciated by post-contrast TF. Our results demonstrate that Gd-DTPA TF imaging improves visualization of the main portal vein compared with SE sequences and provides a more accurate assessment of vessel patency. The segmental anatomy of the liver is better appreciated and the demonstration of focal liver lesions compared with T2W-SE images is improved during the non-equilibrium phase of enhancement. TF acquisitions before and after Gd-DTPA are obtained in approximately 5 min; thus a marked reduction in examination time can be achieved.

Skeletal muscle lymphoma

It is rare for lymphoma to present as a primary muscle lesion. The computed tomography (CT) features are described in three cases. Muscle involvement was the only manifestation of lymphoma in two, and in all three cases, contrast enhancement of the soft tissue mass occurred.

Primary malignant localized fibrous tumours of the pleura: clinical, radiological and pathological features

Localized fibrous tumours of the pleura are rare primary pleural tumours that may exhibit malignant behaviour in approximately 20% of cases. The clinical, radiological and pathological features of five patients with malignant localized fibrous tumours of the pleura are presented. Clinical symptoms included chest pain, breathlessness and cough. Hypertrophic pulmonary osteoarthropathy (HPOA) occurred in one patient. Chest radiographs and thoracic computed tomography (CT) demonstrated large necrotic masses, with focal calcification and compressive atelectasis of the underlying lung. Histological features were variable and resulted in designation of these tumours as localized fibrous tumours of the pleura of low or high grade malignancy. The grading of malignancy did not correlate with final outcome, adequacy of surgical excision being the most important factor. These tumours have been referred to as benign pleural fibromas or localized mesotheliomas, but these names are inaccurate and the term localized fibrous tumour of the pleura is to be preferred. This term should also include tumours such as malignant fibrous histiocytoma of the pleura.

Dynamic contrast enhanced computed tomography: a precise technique for identifying and localising pancreatic necrosis

OBJECTIVE

To evaluate dynamic contrast enhanced computed tomography for detecting and localising pancreatic necrosis in acute pancreatitis.

DESIGN

Prospective evaluation with blind reporting of scans.

SETTING

Single teaching hospital.

PATIENTS

60 Consecutive patients with acute pancreatitis suspected to have pancreatic necrosis because of major organ system failure (13); slow recovery five to seven days after admission with raised scores on the acute physiological and chronic health evaluation (APACHE-II) system (27); or findings on previous ultrasonography or computed tomography (20).

MAIN OUTCOME MEASURE

Pancreatic necrosis proved histologically--that is, greater than 30 g necrotic tissue debrided at laparotomy (for life threatening sepsis or peritonitis) or necropsy.

RESULTS

Dynamic computed tomography correctly localised pancreatic necrosis in 11 patients (confirmed at laparotomy in nine and at necropsy in two). Of nine patients with low enhancement of peripancreatic tissues alone, eight recovered after conservative management; necropsy confirmed viable pancreas and necrosis of peripancreatic fat in one patient. Of 40 patients with normal contrast enhancement, none required laparotomy to debride pancreatic necrosis.

CONCLUSION

Dynamic contrast enhanced computed tomography seems to be a safe and accurate method of identifying and localising pancreatic and peripancreatic necrosis, which cannot be predicted accurately by conventional imaging techniques.

Ultrasound demonstration of gas in hepatic veins

We report a case of a gas forming renal abscess in which real time ultrasound demonstrated intravascular gas originating in the abscess passing into the inferior vena cava and hepatic veins.

Debridement and closed cavity irrigation for the treatment of pancreatic necrosis

Pancreatic and peripancreatic debridement combined with a closed cavity system of drainage was used to manage necrotic sequelae of severe acute pancreatitis in 14 patients. Intravenous contrast-enhanced computed tomography, or latterly incremental dynamic computed tomographic angiography, accurately detected and localized necrotic tissue. Operation was delayed where possible to permit demarcation of the necrotic area and the development of a 'capsule' of inflammatory tissue. A retrocolic route of access to the necrotic area was used in nine cases, and purpose-made silicone elastomer tubes with an outside diameter of 20 mm were positioned so that drainage was assisted by gravity when the patient was supine. The cavity was irrigated with saline (initially 2 litres daily), and in the last seven patients Trasylol was included in the irrigation fluid (5 x 10(6) kallidinogenase inactivator (KI) units/litre) for the first postoperative week. Three elderly patients died (mean age 72 years) but all patients aged less than 68 years survived. Planned reoperation was carried out in two patients, but further reoperations were not required in the remaining 11. Drainage tubes were removed when contrast studies showed the cavity to be small and superficial; the median duration of drainage was 28 days. Although sinograms demonstrated fistulae between cavity and small bowel (n = 4) or small bowel and colon (n = 2), no clinical problems resulted and all closed spontaneously. Closed drainage may be as effective as techniques of marsupialization, but avoids the need for frequent relaparotomy.

Endoluminal ultrasound and computed tomography in the staging of rectal cancer

Pre-operative staging of rectal cancer might define patients with disease confined to the rectal wall without lymph node metastases, in whom local excision might be appropriate, or patients with extrarectal spread, who might benefit from pre-operative radiotherapy. With these objectives, 36 consecutive patients with rectal cancer were studied by endoluminal ultrasound: 17 of them also underwent computed tomography (CT) of the pelvis. The results were correlated with the findings at operation and subsequent pathological examination. Endoluminal ultrasound correctly predicted invasion of the tumour through the rectal wall in 86 per cent of patients, with a sensitivity of 96 per cent and specificity of 50 per cent, but correctly identified lymph node metastases in only 61 per cent of patients (sensitivity 57 per cent; specificity 64 per cent). CT correctly predicted invasion through the rectal wall in 94 per cent of cases, with a sensitivity of 100 per cent and specificity of 67 per cent and correctly identified lymph node metastases in 70 per cent of patients (sensitivity 25 per cent; specificity 85 per cent). These findings indicate that both endoluminal ultrasound and CT may be helpful in selecting patients for pre-operative radiotherapy. Neither technique, however, can reliably identify lymph node metastases and therefore cannot be used to select patients who would be suitable for local excision.

Embolisation in small bowel haemorrhage

As embolism of small bowel arteries carries the risk of bowel infarction, the technique is usually reserved for situations where a vasopressin infusion has failed to control bleeding. We report three cases in which embolisation was used as the primary treatment to control small bowel haemorrhage without the complication of bowel infarction.

Typhlitis in acute childhood leukaemia: radiological features

Typhlitis is a necrotising inflammation of the caecum usually found in acute leukaemic patients on chemotherapy. We described the radiological features of two children with this complication. The first was diagnosed by an enema using water-soluble contrast medium and the second by ultrasound and computed tomography (CT). A water-soluble contrast medium enema is considered diagnostic in this clinical context and excludes intussusception and, often, appendicitis. Ultrasound showed a rounded mass with dense central echoes and a wider hypoechoic periphery. Computed tomography showed the long segment of thick-walled ascending colon and caecum; if perforation is suspected, ultrasound and CT might be preferable to a contrast enema.

Chest radiography for general practitioners--a low yield investigation

Of 1,163 chest rediographs requested by general practitioners, 67.5 per cent were normal, 21 per cent revealed an apparently relevant lesion, and 11.5 per cent an apparently irrelevant abnormality. The number of referrals for chest radiography should be reduced to cut costs in an expensive specialty.

Relation of Soil Water Movement and Sulfide Concentration to Spartina alterniflora Production in a Georgia Salt Marsh

It is proposed that differences in plant height and productivity of the salt-marsh cordgrass Spartina alterniflora are the result of a dynamic interaction among tidal water movement, dissolved iron and sulfide concentrations in marsh soils, and bacterial sulfate reduction. Tidal water movement regulates the input of iron into marsh soils and the drainage of sulfide-containing interstitial water, and thereby controls the concentration of dissolved sulfide formed as a result of bacterial sulfate reduction. Near tidal creeks, where water movement and plant height and production are greatest, sulfide concentrations are lowest; in more elevated regions of marsh, where water movement andplant production are least, sulfide concentrations are highest. Plant height and productivity may be limited by the effects of sulfide on nutrient uptake.

A comparison and an investigation of a potential synergistic effect of labetalol and bethanidine in patients with mild hypertension

1 The effects of labetalol, bethanidine and combined treatment with both drugs were compared in a within-patient randomized cross-over study in mild essential hypertension. Attention was directed to whether or not labetalol and bethanidine differed in their pattern of effect on arterial BP and whether evidence of synergism was apparent. 2 At the doses used labetalol significantly lowered systolic and diastolic BPs and heart rate lying, sitting, standing and after exercise. The dose of bethanidine used did not affect heart rate significantly while lowering systolic and diastolic BPs only after exercise and less clearly on standing. Combined treatment lowered BPs on standing and after exercise and heart rate after exercise. 3 The type and frequency of side-effects were similar with bethanidine and labetalol but were much less with combined treatment. 4 No evidence of synergism was observed.