Denitrifying bioreactors and dissolved phosphorus: Net source or sink?

Understanding the world through a lens of phosphorus (P), as Dr. Andrew Sharpley aimed to do, adds a deeper dimension for water quality work in the heavily tile-drained US Midwest where nitrate is often the nutrient of biggest concern. Denitrifying woodchip bioreactors reduce nitrate pollution in drainage water, but dissolved phosphorus leached from the organic fill is a possible pollution tradeoff. Recent work by Dr. Sharpley and others defined such tradeoffs as strategic decisions in which a negative outcome is accepted with prior knowledge of the risk. In this vein, we assessed 23 site-years from full-size bioreactors in Illinois to determine if bioreactors were a net dissolved reactive phosphorus (DRP) source and, if so, to determine flow-related correlation agents (1904 sample events; 10 bioreactors). DRP was removed across the bioreactors in 15 of 23 site-years. The 23 site-years provided a median annual DRP removal efficiency of 12% and a median annual DRP removal rate of 7.1 mg DRP/m3 bioreactor per day, but the ranges of all removal metrics overlapped zero. The highest daily bioreactor DRP removal rates occurred with high inflow concentrations and under low hydraulic retention times (i.e., under higher loading). Dr. Sharpley was one of the first to explore losses of DRP in subsurface drainage and performed decades of useful applied studies that inspired approaches to management of P loss on both drained and undrained land. We seek to honor this legacy with this practical study of the DRP benefits and tradeoffs of denitrifying bioreactors.

Susceptibility of primary human endothelial cells to C. perfringens beta-toxin suggesting similar pathogenesis in human and porcine necrotizing enteritis.

Clostridium perfringens type C causes fatal necrotizing enteritis in different mammalian hosts, most commonly in newborn piglets. Human cases are rare, but the disease, also called pigbel, was endemic in the Highlands of Papua New Guinea. Lesions in piglets and humans are very similar and characterized by segmental necro-hemorrhagic enteritis in acute cases and fibrino-necrotizing enteritis in subacute cases. Histologically, deep mucosal necrosis accompanied by vascular thrombosis and necrosis was consistently reported in naturally affected pigs and humans. This suggests common pathogenetic mechanisms. Previous in vitro studies using primary porcine aortic endothelial cells suggested that beta-toxin (CPB) induced endothelial damage contributes to the pathogenesis of C. perfringens type C enteritis in pigs. In the present study we investigated toxic effects of CPB on cultured primary human macro- and microvascular endothelial cells. In vitro, these cells were highly sensitive to CPB and reacted with similar cytopathic and cytotoxic effects as porcine endothelial cells. Our results indicate that porcine and human cell culture based in vitro models represent valuable tools to investigate the pathogenesis of this bacterial disease in animals and humans.

Hypothenar hammer syndrome: a discrete syndrome to be distinguished from hand-arm vibration syndrome.

BACKGROUND: Hypothenar hammer syndrome (HHS) is a cause of vascular insufficiency to the hand and may be manifest as Raynaud's phenomenon. The cause is trauma to the vulnerable portion of the ulnar artery as it passes over the hamate bone, which may result in thrombosis, irregularity or aneurysm formation. AIM: This review was undertaken in order to clarify the features of HHS that may differentiate it from hand-arm vibration syndrome. METHODS: A tiered review of world literature was undertaken using Medline and EMBase as the primary search engines. Fifty-two relevant articles were critically reviewed. CONCLUSION: Colour and temperature changes occur more diffusely in HHS than in classical Raynaud's phenomenon and the absence of the triphasic colour change may alert clinicians to the diagnosis, which may be confirmed by Allen's test. Doppler or arteriographic studies are required for confirmation. It is important to recognize the possibility of HHS in the occupational setting as a potentially curable cause of Raynaud's phenomenon, distinct from hand-arm vibration syndrome. The possibility exists of HHS occurring as a result of repeated hypothenar trauma from vibrating tools, in which case the nature and magnitude of the individual episode of trauma may be more important than the weighted acceleration level of vibration exposure.

Thoracic outlet syndrome--aspects of diagnosis in the differential diagnosis of hand-arm vibration syndrome.

BACKGROUND: Thoracic outlet syndrome (TOS) is a cause of vascular and neurological compromise to the arm and hand, and may manifest as Raynaud's phenomenon. It may be under-diagnosed. AIM: This review was undertaken in order to clarify the diagnostic and investigative features of TOS that may differentiate it from hand-arm vibration syndrome. METHODS: A tiered review of the world literature was undertaken using Medline and Embase as the primary search engines. CONCLUSION: Thoracic outlet syndrome most commonly presents with neurological symptoms in the arm. Vascular symptoms, including Raynaud's phenomenon, may occur in approximately 10% of cases. Careful clinical assessment by history and examination may reveal the elements of forearm and upper arm symptoms with postural exacerbation, which distinguish this condition from hand-arm vibration syndrome. The usefulness of investigation is unclear, but Doppler and neuroelectric studies may be valuable. Magnetic resonance imaging scan is the investigation of choice.

Patent foramen ovale in elderly stroke patients.

The aim of this study was to determine the incidence of echocardiographically detectable patent foramen ovale (PFO) in elderly patients who have strokes from cerebral infarction, as well as to assess the association between PFOs and other risk factors for stroke disease. Forty-three patients aged > or = 65 years admitted consecutively with cerebral infarction shown on computerised tomography of the brain were assessed using transoesophageal echocardiography. A PFO was present in 8 (19%) of the 43 patients. Four patients (50%) in this PFO group had stroke risk factors. Two were in atrial fibrillation and, of the six patients in sinus rhythm, a risk factor was present in two, both of whom had diabetes mellitus. A PFO was not detected in 35 patients. Twenty-nine (83%) of the patients in this group had risk factors, with 18 having two or more. Seven patients were in atrial fibrillation. Of the 28 patients in sinus rhythm, risk factors were present in 22 (78%).

Primary osteogenic sarcoma of the tongue.

A 56-year-old man presented with the difficulty of swallowing and respiratory distress due to a large tumour arising from the tongue and occupying the entire oral cavity. Histological examination revealed it to be an extraskeletal osteogenic sarcoma. The tumour was excised. After six weeks, he came back with massive local recurrence and bleeding from the tumour, but died despite chemotherapy. Review of the literature revealed only four other such cases of this rare tumour. A brief review of these four cases is also made.

A prospective study of oesophageal function in patients with normal coronary angiograms and controls with angina.

AIMS: To compare the incidence of oesophageal abnormalities and their correlation with chest pain in patients with normal coronary angiograms, and in controls with angina. PATIENTS: Sixty one patients with normal coronary angiograms (NCA group) referred to a single cardiac centre between March 1990 and April 1991; 25 matched controls with confirmed coronary artery disease (CAD group). SETTING: Cardiac referral centre and oesophageal function testing laboratory. MAIN OUTCOME MEASURES: Oesophageal manometry, provocation tests, and 24 hour ambulatory pH monitoring. RESULTS: Simultaneous contractions were more common (6.7% versus 0.8%, p < 0.01), and the duration of peristaltic contractions was longer (2.9 versus 2.4 seconds, p < 0.01) in the NCA group than in the CAD group. There were no group differences in the amplitude of peristaltic contractions, and none had nutcracker oesophagus. Ten (16%) patients with NCA and no patients with CAD had diffuse spasm (p = 0.03). Twenty one (34%) patients with NCA, and five (20%) patients with CAD had abnormal gastro-oesophageal reflux (p > 0.05). There was no significant difference between the groups in the number of patients whose pain was temporally related to pH events. Particular chest pain characteristics, or the presence of additional oesophageal symptoms, were not predictive of an oesophageal abnormality. CONCLUSION: Oesophageal function tests commonly implicate the oesophagus as a source of pain in patients with normal coronary angiograms. With the exception of simultaneous contractions during manometry however, the incidence of abnormalities and in particular the correlation of pH events with chest pain are as common in patients with normal coronary angiograms as in controls with angina. The oesophagus may often be an unrecognised source of pain in both groups of patients.

Hepatitis B--are surgeons putting patients at risk?

The 1993 Department of Health guidelines permit a surgeon who is hepatitis B surface antigen (HBsAg) positive but e-antigen (HBeAg) negative to perform exposure prone procedures, unless demonstrated to have infected patients. However, there is increasing evidence of transmission of hepatitis B to patients from health care workers in this supposedly low infectivity category. The Occupational Physician must decide whether existing guidelines represent an adequate risk assessment and indeed whether this is an acceptable risk for patients. If an NHS Trust continues to follow these guidelines it may be in breach of its duty of care to patients. Yet refusing to allow such carriers to operate without testing for additional serological markers may be unlawful discrimination. Further research is clearly needed as well as an urgent review of the guidelines.

Comparative study of chest pain characteristics in patients with normal and abnormal coronary angiograms.

OBJECTIVE: To improve the characterisation of chest pain by comparing symptoms in patients with normal and abnormal coronary angiograms. STUDY DESIGN: Prospective case-control study. SETTING: Single tertiary cardiac referral centre. PATIENTS: 65 consecutive patients with chest pain and completely normal coronary angiograms recruited over a period of one year, and 65 sex matched patients with significant stenoses at angiography. MAIN OUTCOME MEASURES: Standardised chest pain questionnaires. RESULTS: 61 of 65 patients (94%) and every control reported chest pain on exertion. There were no important differences in the site, quality, and radiation of pain but three symptoms had discriminatory value expressed in binary fashion ("typical" v "atypical"): the consistency with which pain was reproduced by exercise (typical, score index 10/10), the duration of pain episodes (typical, five minutes), and the frequency of pain at rest (typical, 10% all pain episodes). All three symptoms were atypical in 21 (32%) patients with normal coronary angiograms, but only one patient with an abnormal coronary angiogram. Patients with no typical features had a 2% chance of an abnormal coronary angiogram if aged under 55 years or 12% if aged 55 years or more. The additional impact of exercise stress testing was low. CONCLUSIONS: Chest pain characteristics which separate patients with normal coronary angiograms from patients with obstructive coronary heart disease can be defined objectively. This may allow improvements in referral patterns for specialist opinion or angiography, and in characterisation of patients in research studies.

Haemodynamic changes during dobutamine stress echocardiography in patients with and without ischaemia.

We studied haemodynamic changes during dobutamine stress echocardiography in 69 patients (mean age 58 years, 6 female, 63 male) referred for investigation of chest pain. We used a standard protocol of 3 min stages using infusion rates of 5, 10, 20, 30 and 40 micrograms/kg/min. Heart rate rose from 74 (13) to 123 (21) beats per min with the major increment occurring during the high dose phase of the study (> 20 micrograms/kg/min). Stroke volume was calculated as the product of left ventricular outflow tract cross-sectional area and the velocity integral of the continuous wave aortic signal. Mean stroke volume increased from 67.5 (22) ml pre-test to 82 (22) ml at 20 micrograms/kg/min dose (P < 0.0001) and 85 (21) ml at 40 micrograms/kg/min (P < 0.00001). Only 15 patients (26%) reached their maximal stroke volume by 10 micrograms/kg/min, 38 patients (65%) reached maximal stroke volume by 20 micrograms/kg/min. Patients with ischaemic responses tended to have a blunted rise in stroke volume from 67 (22) ml to 85 (22) ml at maximum compared with a rise from 69 (23) to 92 (19) ml in those without ischaemic (P = 0.09). In conclusion, the early rise in cardiac output during dobutamine stress was mainly due to a rise in stroke volume and the later due to an increase in heart rate. Individual increases in stroke volume did not adequately differentiate between ischaemic and non-ischaemic results.

Essential acquired cold urticaria: stimulated only by systemic as well as local cooling.

The background and differential diagnosis of essential acquired cold urticaria are discussed. The case report is of a 22-year old male who had previously been diagnosed as suffering from eczema. Working in a cold environment, with both systemic and local cooling stimulated development of an urticaria rash, diagnosed as being essential acquired cold urticaria.

A comparison of valve resistance, the continuity equation, and the Gorlin formula against directly observed orifice area in bioprosthetic valves in the mitral position: an in vitro study.

BACKGROUND AND AIMS OF THE STUDY: There is no consensus over how to describe forward flow through valves in the mitral position. There are three main candidate hydraulic formulae; resistance, the Gorlin formula and the continuity equation. However, virtually no work has been performed to validate resistance and the continuity equation for valves in the mitral position. The aim of this study, therefore, was to compare the three formulae against an independent standard provided by directly observed orifice areas. MATERIALS AND METHODS: Five bioprosthetic valves with orifice areas between 0.14 cm2 and 2.33 cm2 were studied in a pulse simulator at up to 20 different stroke volume/rate combinations using quasi-physiologic flow curves. Orifice areas were measured using a video camera, pressure difference using strain gauge transducers and Doppler signals using a 1.9 MHz Pedoff probe with a Vingmed SD50 system. RESULTS: The Gorlin ratio (flow/square root of mean delta P) had a direct curvilinear relationship with the orifice area (log(y) = 0.31 + 0.36x; r = 0.94, SEE 0.08 cm2, p < 0.0001). Resistance (mean delta P/flow) had an indirect curvilinear relationship (log(y) = 0.19 - 0.55x, r = -0.93, SEE 0.13 cm2, p < 0.0001). The continuity equation was directly related to observed orifice area although with high scatter (y = 1.13 + 0.79x; r = 0.90, SEE 0.23 cm2, p < 0.0001). Although both the Gorlin ratio and resistance changed with flow, there was also a tendency for observed orifice areas to increase with flow. Empirical effective orifice areas calculated using the regression equations closely resembled observed orifice areas and agreement was reasonable, with 95% limits of -0.33 cm2 to +0.33 cm2 (Gorlin), -0.41 cm2 to +0.42 cm2 (resistance) and -0.40 cm2 to +0.48 cm2 (continuity). CONCLUSION: In conclusion, no single formula adequately predicted all observed orifice areas although resistance and the Gorlin formula gave useful predictions after empirical correction.

Hyperventilation and esophageal dysmotility in patients with noncardiac chest pain.

OBJECTIVES: Hyperventilation is known to cause esophageal spasm, but the importance of this interaction in clinical practice is unknown. In the present study, we report the effects of hyperventilation provocation on esophageal motility in a consecutive series of patients with noncardiac chest pain. METHODS: In a prospective observational study design, 46 consecutive patients with normal coronary angiograms were studied. Esophageal motility was recorded at rest and after voluntary over-breathing at 40 breaths/min for 3 min. RESULTS: Hyperventilation was associated with a significant fall in mean distal peristaltic amplitude [66 (SD 28) to 55 (SD 24) mm Hg, p <0.001] and mean duration [2.9 (SD 0.7) to 2.6 (SD 0.9) s,p = 0.02]. It induced diffuse spasm in two (4%) patients, and nonspecific motility disorders in 10 (22%). Chest pain was reproduced in seven (15%) patients, but in none did this coincide with an important change in peristaltic amplitude, duration, or frequency. CONCLUSION: Hyperventilation has important effects on esophageal motility, and manometrists should be aware of these before recommending that anxious patients overbreathe to help relaxation during clinical studies. Although overbreathing is a common source of dysmotility, it rarely produces chest pain via its effects on the esophagus.

Malignant lymphomas in Papua New Guinea: an immunohistological study of 125 cases.

A total of 179 cases of lymphoma, both nodal and extranodal, recorded in the Papua New Guinea Tumor Registry were reviewed and classified by the updated Kiel classification. Fifteen (8.4%) were Hodgkin's disease, 39 (21.8%) probable Burkitt's lymphoma (poorly preserved), 46 (25.7%) Burkitt's lymphoma, 33 (18.4%) Burkitt's-like lymphoma, 36 (20.1%) other B-cell subtypes and 10 (5.6%) T-cell lymphoma. No case of follicular B-cell lymphoma was encountered.

Anorexia nervosa and the heart.

Anorexia nervosa is an eating disorder which predominantly affects young females. A variety of cardiovascular complications are described. These include lengthening of the QT interval and other electrocardiographic abnormalities, reduced left ventricular mass and impaired myocardial performance, mitral valve prolapse and sudden death. The incidence of these abnormalities and their relation to outcome are discussed in this article.

Liver disease in Papua New Guinea 1981 to 1988, twenty years after the first surveys were done.

Twenty years after the first surveys of liver disease were done cirrhosis and hepatocellular carcinoma were still found to be the most important liver diseases in Papua New Guinea. Hepatitis B virus appears to be the main cause of both these conditions. Data from a number of different sources suggest a prevalence of hepatitis B positivity of about 17%. The most significant new finding was grade 3 iron deposition in 8 patients. This raises the question as to whether iron storage disease may now contribute to the spectrum of liver disease in Papua New Guinea. Many biopsies in the 1960s and 1980s were interpreted as nonspecific hepatitis; in the light of recent observations, at least some of these may have been due to hepatitis C infection.