Burnout in trauma and orthopaedics: a cross-sectional study of surgeons from across the United Kingdom

INTRODUCTION

Improving psychological wellbeing in healthcare professionals has demonstrable links with improvements in system-performance and patient outcomes. The aims of this study were to determine the prevalence of burnout among orthopaedic surgeons within the United Kingdom (UK) and to identify any influencing factors.

METHODS

This prospective, cross-sectional nationwide study used the Oldenburg Burnout Inventory to assess burnout among orthopaedic registrars, middle grades and consultants from across the UK. In total, 369 participants completed an anonymised online survey. Reasons for burnout were assessed using a list of 20 stressors followed by a white-space box for elaboration.

RESULTS

Respondents included 204 (55.3%) consultants, 100 (27.1%) registrars and 65 (17.6%) who were an associate specialist, trust grade or fellow. Some 252 (68.3%) participants experienced moderate-level burnout and 81 (22.0%) high-level burnout. There was no significant association between burnout and grade (p = 0.283), gender (p = 0.433), marital status (p = 0.932), years since graduation (p = 0.397), overseas training (p = 0.642), hours worked (p = 0.601), region (p = 0.699) or hospital type (p = 0.813). A high level of disengagement and exhaustion were identified, with the latter being a greater contributory factor. The most common reasons for burnout were insufficient staff numbers, an overload of administrative work and limited time to see patients.

CONCLUSION

There was a moderate to high level of burnout among orthopaedic surgeons within the UK. Clinical and management teams should focus on improving staff numbers, reducing administrative work and increasing clinic consultation times to limit any further disengagement and exhaustion from surgeons. Reducing burnout may help to improve mental wellbeing, work satisfaction and workforce productivity.

Maladaptive autophagy in the pathogenesis of autoimmune epithelitis in Sjӧgren's Syndrome

OBJECTIVE

Salivary gland epithelial cells (SGECs) are key cellular drivers in the pathogenesis of primary Sjӧgren's Syndrome (pSS); however, the mechanisms sustaining SGECs activation in pSS remain undetermined. The aim of this study is to determine the role of autophagy in the survival and activation of SGECs in pSS.

METHODS

Primary SGECs isolated from minor salivary glands (SG) of patients with pSS or sicca syndrome were evaluated by flow-cytometry, immunoblotting, and immunofluorescence to assess autophagy (autophagic-flux, LC3IIB, p62, LC3B+/LAMP1+ staining), apoptosis (annexin V/PI, Caspase-3) and activation (ICAM, VCAM). Focus score and germinal centers presence was assessed in SG from the same patients to correlate with histological severity. Human salivary gland (HSG) cells were stimulated in vitro with PBMCs and serum from pSS patients in the presence or absence of autophagy inhibitors to determine changes in autophagy and epithelial cell activation.

RESULTS

SGECs from pSS patients (n=24) exhibited increased autophagy (autophagic-flux p=0.001; LC3IIB p=0.02; p62 p=0.064; LC3IIB/LAMP1+ staining), increased expression of anti-apoptotic molecules (Bcl2 p=0.006), and reduced apoptosis (Annexin-V/PI p=0.002, Caspase-3 p=0.057) compared to sicca (n=16). Autophagy correlated with histologic disease severity. In vitro experiments on HSG cells stimulated with serum and PBMCs from pSS patients confirmed activation of autophagy and expression of adhesion molecules, which was reverted upon pharmacologic inhibition of autophagy.

CONCLUSIONS

In pSS SGECs, inflammation induces autophagy and pro-survival mechanisms, which promote SGEC activation and mirror histological severity. These findings indicate that autophagy is a central contributor to the pathogenesis of pSS and a new therapeutic target.

Reversal of direct oral anticoagulants in adult hip fracture patients. A systematic review and meta-analysis

BACKGROUND

Increasing numbers of patients are taking Direct Oral Anticoagulants at the time of hip fracture. Evidence is limited on how and if the effects of DOAC's should be reversed before surgical fixation. Wide variations in practice exist. We conducted a systematic review to investigate outcomes for three reversal strategies. These were: "watch and wait" (also referred to as "time-reversal"), plasma product reversal and reversal with specific antidotes.

METHODS

A systematic search was conducted using multiple databases. Results were obtained for studies directly comparing different DOAC reversal strategies in hip fracture patients and for studies comparing DOAC-taking hip fracture patients (including patients "reversed" using any method and "non-reversed" patients) against matched controls taking either a vitamin-K antagonist or not receiving anticoagulation therapy. This allowed construction of a network meta-analysis to indirectly compare outcomes between "reversed" and "non-reversed" DOAC patients. With respect to "watch and wait"/"time-reversal", a cut-off time to surgery of 36 hours was used to distinguish between "time-reversed" and "non time-reversed" DOAC patients. The primary outcome was early/inpatient mortality, reported as Odds Ratios (OR).

RESULTS

No studies investigating plasma products or reversal agents specifically in hip fracture patients were obtained. Fourteen studies were suitable for analysis of "watch and wait"/"time- reversal". Two studies directly compared "time-reversed" and "non time-reversed" DOAC-taking hip fracture patients (58 "time-reversed", 62 "non time-reversed"). From 12 other studies we used indirect comparisons between "time-reversed" and "non time-reversed" DOAC patients (total, 357 "time-reversed", 282 "non time-reversed"). We found no statistically significant differences in mortality outcomes between "time-reversal" and "non time-reversal" (OR 1.48 [95%CI: 0.29-7.53]). We also did not find a statistically significant difference between "time reversal" and "non time-reversal" in terms of blood transfusion requirements (OR 1.16 [95% CI 0.42-3.23]). However, several authors described that surgical delay is associated with worse outcomes related to prolonged hospitalisation, and that operating within 36 hours is safe.

CONCLUSIONS

We suggested against "watch and wait" to reverse the DOAC effect in hip fractures. Further work is required to assess the optimal timing for surgery as well as the use of plasma products or specific antidotes in DOAC-taking hip fracture patients.

927 Efficacy of Surgical Helmet Systems for Protection Against COVID-19: A Double-Blinded Randomised Control Study

Introduction

This study assesses whether sterile surgical helmet systems (SSHS) provide additional protection from aerosol pathogens alongside protecting against splash. There has been debate on whether to use such systems in orthopaedic surgery during the COVID-19 pandemic.

Method

Thirty-five participants were enrolled in a double-blinded randomised controlled study investigating efficacy of the Stryker Flyte Surgical Helmet (Stryker Corporation, Kalamazoo, MI, USA) as protection against respiratory droplets. Wearing the SSHS in a fit testing hood, subjects were randomised to nebulised saccharin solution or placebo. Twenty were allocated to the saccharin group with 15 to placebo. Positive sweet taste represented test failure. Taste tests were performed with the helmet fan turned on and off.

Results

SSHS did not prevent saccharin taste (p < 0.0001). Within the saccharin cohort, 40% recorded a positive taste with the fan on and 100% with the fan off. There was a statistically significant difference in mean time-to-taste saccharin (p = 0.049) comparing fan on (123.5 s) vs. off (62.6 s).

Conclusions

SSHS do not protect against aerosol particulate and therefore are not efficacious in protection against COVID-19. The fan system employed may even increase risk by drawing in particulates and delaying recognition of intraoperative cues that point to respirator mask leak.

Waterlow score for risk assessment in surgical patients: a systematic review

INTRODUCTION

The Waterlow score (WS) is used routinely in clinical practice to assess risk of pressure sore development. Recent studies have also suggested its use in preoperative risk stratification. The primary aim of this systematic review was to evaluate the current evidence on the WS in predicting morbidity and mortality in surgical patients.

METHODS

A systematic review was carried out in accordance with PRISMA and SWiM guidelines. A search strategy was conducted on the MEDLINE and EMBASE databases. Quality was assessed using the Newcastle-Ottawa scale.

FINDINGS

Overall, 72 papers were identified, of which 7 met inclusion criteria for full text review, and 4 were included for analysis. All studies were cohort in nature and published between 2013 and 2016, encompassing a total of 505 surgical patients. The studies included general, vascular, transplant and orthopaedic surgery. A high WS was demonstrated to have statistically significant association with increased morbidity and mortality as well as need for intensive care unit admission and length of stay. Furthermore, this was a more accurate predictor compared with the P-POSSUM and ASA scoring systems used currently in routine practice.

CONCLUSIONS

The WS is a promising tool for risk stratification of surgical patients. It is already collected routinely by nursing staff throughout hospitals in the UK and would therefore be easy to implement. However, further large prospective studies are required in order to validate these findings prior to its establishment for this role in everyday surgical practice.

THU0220 AUTOPHAGY IN SJOGREN’S SYNDROME SALIVARY GLAND EPITHELIAL CELLS (SGECS) IS ASSOCIATED WITH THE SEVERITY OF INFLAMMATION AND EPITHELIAL CELLS ACTIVATION

Background:

Sjögren’s Syndrome (SS) is characterized by chronic inflammation supported by intrinsic activation of salivary gland epithelial cells (SGECs). Eventually, apoptosis of SGECs ensues, which leads to salivary gland dysfunction and exposition of autoantigens. Autophagy is a stress coping mechanisms of cells implicated in both survival and exposition of autoantigens, and is thereby plausibly implicated in the pathogenesis of SS. At present, the exact relationship between apoptosis and autophagy in SS SGECs is unclear, as is the link between these mechanisms and SGECs activation.

Objectives:

To explore autophagy in SGECs from patients with SS and to evaluate its relationship with apoptosis and SGECs activation.

Methods:

Consecutive patients with suspected SS referring to our “Sjogren Clinic” were enrolled, and minor salivary gland (MSG) biopsies were collected for: (1) SGECs culture, (2) PCR analysis, (3) IFI analysis. In SGECs cultures, the expression of autophagy (LC3II), apoptosis (annexin V/PI) and adhesion molecules (ICAM) was investigated by flow cytometry (results expressed as mean % ± SD). The expression of the autophagy gene MAP1LC3II was evaluated by PCR (expressed as 2^deltaCT normalized to GADPH) on both MSG sections and MSG acinar and ductal epithelium samples obtained by laser capture microdissection. Tissue expression of LC3II was evaluated by IFI on SS MSG.

Results:

Primary SGECs cultures were established from 14 MSG obtained for diagnostic purposes (SS n=8, Sicca n=6). These cells exhibited an inverse correlation between apoptosis and autophagy (p=0.007, r=-0.784), with lower levels of apoptosis (19.7±6.5 vs 24.5±8.5, p=ns) and higher levels of autophagy (59.7±13.1 vs 54.19±19.4, p=ns) in SS compared to Sicca. In SS, MAP1LC3 was positively correlated with Focus Score (p=0.021 r=0.478); however, PCR studies did not reveal significant differences in MAP1LC3 expression between SS (n=26) and Sicca (n=15) (0.024±0.010 vs 0.022±0.008, p=ns). Ductal SGECs (n=4) isolated by laser microdissection of MSG revealed a higher expression of MAP1LC3 (0.005±0.0005 vs 0.003±0.0008; p=0.057) compared to normal acinar epithelium (n=5); a major expression of LC3II in ducts was confirmed by IFI (Image).

In SS, a higher expression of ICAM compared to sicca was observed (11.1±3.8 vs 6.9±6.9, p=0.006) and autophagy and apoptosis showed a trend of positive and negative correlation with this molecule, respectively (p=0.683 r=0.118 and p=0.106 r=-0.446).

Figure.

LC3-II staining in SS MSG [LC3-II+ (green) and Hoechst stain (blue); 60x magnification].

Conclusion:

In SS, autophagy is upregulated in SGECs and inversely correlated with apoptosis, thus supporting a role of this process in cells’ death prevention during inflammatory process. Indeed, the degree of msg inflammation is correlated more with the activation of autophagy than apoptosis. Interesting, in SS, SGECs autophagy is mainly observed at ductal level and is correlated with higher expression of adhesion molecules suggesting a link between this pathway and changes in SGECs immune phenotype.

Disclosure of Interests: :

Serena Colafrancesco: None declared, cristiana barbati: None declared, Valentina Iannizzotto: None declared, Linda Mastromanno: None declared, Saba Nayar: None declared, Elena Pipi: None declared, angelica gattamelata: None declared, francesco ciccia Grant/research support from: pfizer, novartis, roche, Consultant of: pfizer, novartis, lilly, abbvie, Speakers bureau: pfizer, novartis, lilly, abbvie, cristiano alessandri Grant/research support from: Pfizer, Francesca Barone: None declared, fabrizio conti Speakers bureau: BMS, Lilly, Abbvie, Pfizer, Sanofi, Roberta Priori: None declared

An Unusual Case of Pulmonary Mucormycosis

Invasive fungal infections in solid organ transplant recipients are associated with significant morbidity and mortality. Of these fungal infections, mucormycosis presents as an aggressive, frequently fatal angioinvasive infection. Immunocompromised hosts and diabetes are important risk factors. These infections are frequently difficult to diagnose. A high index of suspicion in the appropriate setting and early, aggressive treatment with the newer antifungal agents have altered the previously grave prognosis. We present the first reported case of cavitating pulmonary mucormycosis in a renal transplant recipient caused by an unusual species of Mucorales. The patient was treated with a combination of lobectomy and antifungal treatment comprising of amphotericin B and posaconazole. He remains free of disease recurrence on monotherapy with posaconazole.

Isolated Neurogenic Bladder Associated With Human T-Lymphotropic Virus Type 1 Infection in a Renal Transplant Patient From Central Australia: A Case Report

BACKGROUND

Human T-lymphotropic virus type 1 (HTLV-1) is endemic amongst the Aborigines of the Northern Territory of Australia. HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) has been associated with this infection. In general population, isolated neurogenic bladder dysfunction in HTLV-1-infected individuals without HAM/TSP has been reported, and the HTLV-1 proviral load has been found to be higher in such patients compared with asymptomatic carriers. In solid organ transplantation, few cases of HAM/TSP have been reported worldwide, but not an isolated neurogenic bladder.

CASE

A 50-year-old indigenous women from Alice Springs with end stage renal disease secondary to diabetic nephropathy with no prior history of bladder dysfunction received a cadaveric renal allograft following which she developed recurrent urinary tract infections. The recipient was seropositive for HTLV-1 infection. HTLV-1 status of donor was not checked. Urodynamic studies revealed stress incontinence and detrusor overactivity without urethral intrinsic sphincter deficiency. She had no features of myelopathy. There was elevation of the serum and cerebrospinal fluid HTLV-1 proviral load. The magnetic resonance imaging myelogram was normal. Pyelonephritis was diagnosed based on clinical features, positive cultures, and renal allograft biopsy. Continuous suprapubic catheter drainage helped preventing further episodes of allograft pyelonephritis in spite of chronic colonization of the urinary tract.

CONCLUSION

Isolated bladder dysfunction is a rare manifestation of HTLV-1 infection and is probably associated with high proviral loads. This may adversely affect renal allograft and patient outcomes.

Molecular and Cellular Requirements for the Assembly of Tertiary Lymphoid Structures

At sites of chronic inflammation, recruited immune cells form structures that resemble secondary lymphoid organs (SLOs). Those are characterized by segregated areas of prevalent T- or B-cell aggregation, differentiation of high endothelial venules (HEVs) and local activation of resident stromal cells. B-cell proliferation and affinity maturation towards locally displayed autoantigens have been demonstrated at those sites, known as tertiary lymphoid structures (TLSs). TLS formation has been associated with local disease persistence and progression as well as increased systemic manifestations. While bearing a similar histological structure to SLO, the signals that regulate TLS and SLO formation can diverge, and a series of pro-inflammatory cytokines has been ascribed as responsible for TLS formation at different anatomical sites. Here we review the structural elements as well as the signals responsible for TLS aggregation, aiming to provide an overview to this complex immunological phenomenon.

Uptake of inorganic phosphorus by temperate seagrass beds of Posidonia and Amphibolis in Southern Australia

Seagrasses occupy a narrow band of sandy seabed close to the coast and are therefore vulnerable to anthropogenic influences, particularly meadows near large population centres. Over 5000 ha of seagrasses have been lost from Adelaide coastal waters (South Australia) over the past 70 years and much of this loss has been attributed to nutrient inputs from wastewater, industrial and stormwater discharges. This led to the Adelaide Coastal Waters Study to understand processes along the Adelaide metropolitan coast that led to seagrass loss. This study, a subset of the larger ACWS study, used in situ nutrient spike approach to obtain ecologically relevant estimates of seasonal variability in phosphorus uptake in two species of temperate seagrass common to this coast (Amphibolis antarctica and Posidonia angustifolia). Total uptake of phosphorus by biological components in the seagrass beds, viz., seagrass, epiphytes and phytoplankton, was negligible, never exceeding 0.5% of the total resource. Phosphorus uptake rate varied seasonally with higher rates in winter (1.49 μmol P.g(-1) DW.h(-1)) and lower rates in spring (0.70 μmol P.g(-1) DW.h(-1)) for Amphibolis and highest in winter (2.09 μmol P.g(-1) DW.h(-1)) and least in spring (0.14 μmol P.g(-1) DW.h(-1)) for Posidonia. Low biological uptake rates of inorganic phosphorus could be attributed to carbonate sediments and particulates in the water column binding inorganic phosphorus, limiting its availability for biological uptake. From an environmental perspective, seagrass beds in the Adelaide coastal waters account for the assimilation of only 5.4% (19.53 t yr(-1)) of the total anthropogenic inputs of phosphorus.

Managing nitrogen inputs into seagrass meadows near a coastal city: flow-on from research to environmental improvement plans

Increased human habitation has led to a 30 to 50-fold increase in nutrient loads to the coastal waters of Adelaide, resulting in the loss of over 5000 ha of seagrass meadows. The rate of loss since the 1940s has been irregular, averaging 85 ha yr(-1), marked by a substantial peak between 1971 and 1977. A modelling approach allowed comparison of the annual input with the annual uptake rates for the different biotic components in the seagrass bed. In 2005, the estimated uptake of ammonium (465 t yr(-1)) and nitrate (3.04 t yr(-1)) by the seagrass and associated epiphytes in the Adelaide region accounted for 31% of the ammonium and <1% of the nitrate that is currently discharged into the coastal waters. Environment Improvement Programs, such as the one implemented in 1996, may reduce the total nitrogen loads to 700 t yr(-1), possibly stemming further losses and facilitating recolonisation of new seagrass.

Uptake and resource allocation of ammonium and nitrate in temperate seagrasses Posidonia and Amphibolis

Ecologically relevant estimates of seasonal variability in nitrogen uptake and allocation in two species of temperate seagrasses were obtained using in situ isotope-labelling approach. Significantly higher uptake rates of ammonium by leaves, roots and epiphytes of Amphibolis than Posidonia were observed. Overall, root uptake rates were lower than other components. Effect of season was not significant for leaves, roots or epiphytes of the two species. However, plankton uptake varied seasonally with higher rates in winter (0.98 mg N g(-1)D Wh(-1)). In contrast, nitrate uptake rates for various components were significantly affected by seasons. Uptake rates by plankton were highest ranging from 0.003 mg N g(-1)D Wh(-1) (summer, Amphibolis) to 0.69 mg N g(-1)DWh(-1) (winter, Posidonia). Uptake of nitrate by roots was negligible. Biotic uptake rates for nitrate were an order of magnitude slower than ammonium, demonstrating an affinity for ammonium over nitrate as a preferred inorganic nitrogen source. Adelaide coastal waters have lost over 5000 ha of seagrasses, much of this attributed to nutrient inputs from wastewater, industrial and stormwater. Managing these inputs into future requires better understanding of the fate of nutrients, particularly biological uptake. This study attempts to quantify uptake rates of nitrogen by seagrasses.

Extramedullary paraspinal hematopoiesis in hereditary spherocytosis

Hereditary spherocytosis (HS) is a common inherited hemolytic anemia due to red cell membrane defects. Extramedullary hematopoiesis is a compensatory response to insufficient bone marrow blood cell production. The preferred sites of extramedullary hematopoietic involvement are the spleen, liver and lymph nodes; but in HS, the posterior paravertebral mediastinum is also commonly involved. We report a case of a 50-year-old male who presented to us in respiratory distress and with bilateral paravertebral posterior mediastinal masses, which on trucut biopsy were found to be extra-hematopoietic masses; and the patient was found to have hereditary spherocytosis.

Co-infection of dengue virus and chikungunya virus in two patients with acute febrile illness

During an outbreak of chikungunya in a dengue hyperendemic area within the Kinta district of Perak, two patients with acute febrile illness were laboratory confirmed to have co-infection of both dengue and chikungunya viruses in their blood. The concomitant presence of two types of viruses transmitted by the same vector in a susceptible population contributed to the resultant event. A good understanding of virus vector ecology in association with population dynamics and wider application of improved laboratory techniques by using different cell-lines suited for optimal replication of each type of virus and the correct utilization of powerful molecular techniques will enhance accurate diagnosis of these infectious diseases.

Outbreak of chikungunya due to virus of Central/East African genotype in Malaysia

Chikungunya is an acute febrile illness caused by an alphavirus which is transmitted by infective Aedes mosquitoes. Two previous outbreaks of chikungunya in Malaysia were due to chikungunya virus of Asian genotype. The present outbreak involved two adjoining areas in the suburb of Ipoh city within the Kinta district of Perak, a state in the northern part of Peninsular Malaysia. Thirty seven residents in the main outbreak area and two patients in the secondary area were laboratory confirmed to be infected with the virus. The index case was a 44-year Indian man who visited Paramakudi, Tamil Naidu, India on 21st November 2006 and returned home on 30th of November 2006, and subsequently developed high fever and joint pain on the 3rd of December 2006. A number of chikungunya virus isolates were isolated from both patients and Aedes albopictus mosquitoes in the affected areas. Molecular study showed that the chikungunya virus causing the Kinta outbreak was of the Central/East African genotype which occurred for the first time in Malaysia.

Environmental effects of dredging on sediment nutrients, carbon and granulometry in a tropical estuary

This monitoring study encompassed a period prior to dredging, during dredging and post dredging between July 1999 to June 2000 in Ponggol estuary located along the northeastern coast of Singapore. Mean concentrations of sediment nutrients in mg x Kg(-1) (+/- standard error of means) prior to dredging, during dredging and post dredging were 9.75 +/- 4.24, 8.18 +/- 4.29 and 11.46 +/- 4.74 for ammonium, 0.08 +/- 0.05, 0.06 +/- 0.02 and 0.09 +/- 0.01 for nitrite, 0.04 +/- 0.04, 0.11 +/- 0.17 and 0.25 +/- 0.30 for nitrate, 4.83 +/- 3.48, 0.77 +/- 0.48 and 8.33 +/- 9.73 for phosphate respectively. Pre dredge, dredge and post dredge levels of total carbon (TC) were 18.5 +/- 3.7, 20.2 +/- 3.5 and 34.6 +/- 12.0, of total organic carbon (TOC) were 10.5 +/- 2.9, 19.5 +/- 3.6 and 34.6 +/- 12.0 and of total inorganic carbon (TIC) were 7.9 +/- 1.0, 0.7 +/- 0.4 and non detectable in the sediments, respectively. Both, sediment nutrients and carbon registered lower concentrations with onset of dredging, with the exception of nitrate and TOC. A shift in sedimentary carbon from inorganic carbon to organic carbon was also observed with the onset of the dredging activities when the organically enriched historically contaminated layer was exposed. Sediment granulometry showed that the sediments in the estuary were predominantly silt and clay prior to dredging, which changed to sand with onset of dredging. Silt load in the sediments was highest post-dredge. Sediment nutrients and sediment organic carbon were observed to associate with the finer fractions (silt and clay) of sediments. Finer fractions of sediments get resuspended during a dredging event and are dispersed spatially as the result of tides and water movements. Prior to this study, the potential for nutrient release and sediment granulometry due to dredging have been suggested, but there have been few studies of it, especially in the tropics. The baseline information gathered from this study could be used to work out effective management strategies to protect similar tropical ecosystems elsewhere, should there be no other alternative to dredging.

Spatio-temporal fluxes in particulate organic carbon in a tropical coastal lagoon

Temporal and spatial variations in particulate organic carbon (POC) in relation to primary production, chlorophyll a, phaeophytin, plankton abundance, secondary production and suspended particulate matter (SPM) were studied monthly for 1 year from April 1996 to March 1997 in a shallow tropical coastal lagoon on the southwest coast of India. Though temporal variations in all components were significant, spatial variabilities were not statistically significant. POC values range from 200 to 5690 mg C m(3) h(-1), while primary production, chlorophyll a, and phaeophytin varied between 0.02 and 14.53 mg C m(-3) h(-1), 0.87 and 23.11 mg m(-3) and 3.02 and 30.581 mg m(-3), respectively. Phytoplankton and zooplankton abundance varied from 0.01 to 655.5 x 10(5) no m(-3) and negligible to 7.08 x 10(5) no m(-3) respectively; secondary production from 10 to 490 mg C m(-3) and SPM between 0.38 and 74.43 x 10(4) mg m(-3) during this study. Temporally, postmonsoon months were observed to have the highest concentrations of POC in the lagoon waters. The bulk of the POC pool in the lagoon was composed of secondary producers (72%), followed by chlorophyll a (21%), phaeophytin (7%) and suspended particulate matter of inorganic origin (< 0.1%).

Generalized mosaicing: polarization panorama

We present an approach to image the polarization state of object points in a wide field of view, while enhancing the radiometric dynamic range of maging systems by generalizing image mosaicing. The approach is biologically-inspired, as it emulates spatially varying polarization sensitivity of some animals. In our method, a spatially varying polarization and attenuation filter is rigidly attached to a camera. As the system moves, it senses each scene point multiple times, each time filtering it through a different filter polarizing angle, polarizance, and transmittance. Polarization is an additional dimension of the generalized mosaicing paradigm, which has recently yielded high dynamic range images and multispectral images in a wide field of view using other kinds of filters. The image acquisition is as easy as in traditional image mosaics. The computational algorithm can easily handle nonideal polarization filters (partial polarizers), variable exposures, and saturation in a single framework. The resulting mosaic represents the polarization state at each scene point. Using data acquired by this method, we demonstrate attenuation and enhancement of specular reflections and semireflection separation in an image mosaic.

Environmental impacts of diesel fuel on bacteria and phytoplankton in a tropical estuary assessed using in situ mesocosms

Dissolved or dispersed petroleum hydrocarbon concentrations (DDPH) were monitored in Ponggol estuary, Singapore, fortnightly from July 1999 to June 2000. DDPH concentrations ranged from 4.4 to 248.9 microg l(-1) and 0.4 to 1099.7 microg l(-1) for surface and subsurface waters, respectively and with mean concentrations of 41.01 microg l(-1) in the water column. Absorbed or adsorbed petroleum hydrocarbon (AAPH) concentrations measured in sediments ranged from 20.6 to 541.0 mg kg(-1), with mean concentrations of 148.23 mg kg(-1). In situ mesocosm studies of bacteria and phytoplankton were based on field monitoring of environmentally measured concentrations of petroleum hydrocarbons, using diesel fuel as the source of contaminant. The mesocosm comprised of 25 L clear polycarbonate carboys incubated in situ for 6 days. Water and sediments from a clean site with undetectable levels of petroleum hydrocarbons were used in controls. The treatment mesocosms comprised of mean and highest concentrations of DDPH and AAPH. The study revealed signs of acute toxicity to autotrophs viz., phytoplankton and autotrophic bacteria in treatments simulating concentrations of diesel fuel found in the sediments. A stimulatory effect was seen at lower concentrations. Bacterial heterotrophs responded positively to all concentrations of diesel fuel because of the abundance of a carbon source, reduced grazing pressure and reduced competition for nutrients from phytoplankton.

Environmental impact of heavy metals from dredged and resuspended sediments on phytoplankton and bacteria assessed in in situ mesocosms

Past and on-going reclamation, dredging, construction and shipping activities impact Ponggol Estuary, located on the northeastern coast of Singapore. Tin, lead, nickel, cadmium, and copper in particulate and dissolved fractions and sediments ranged from ND (undetectable)-92 ppm, ND-303.2 ppm, ND-2818.4 ppm, ND-74.4 ppm and ND-1117.7 ppm, respectively. Intensive dredging activity during the monitoring period may have led to the resuspension and bioavailability of particulate metals. This was tested by the exposure of phytoplankton and bacteria in mesocosms to previously measured environmental levels of heavy metals and the contaminated sediments with the highest heavy metal concentrations from one of the impacted sites. The results showed significant copper toxicity to phytoplankton and autotrophic bacteria, followed by nickel and lead at all concentrations tested. Enhanced rates of heterotrophic bacterial production and total bacterial abundance were observed in treatments with higher metal concentrations. Among the various treatments, particulate and sediment metal concentrations were significantly different from those of the control. Mesocosms using contaminated sediments with the highest metal concentrations compared with the control showed a bioavailability of metals that resulted in the inhibition of phytoplankton and autotrophic bacteria. High concentrations of copper (5.52-11.35 mg L(-1)) and nickel (2.42-2.71 mg L(-1)) observed in the aqueous phase of treatment mesocosms, and attributed to release from the contaminated sediments could account for the toxicity to phytoplankton and autotrophic bacteria.

In situ microcosms to study the impact of heavy metals resuspended by dredging on periphyton in a tropical estuary

Ponggol estuary, located on the northeastern coast of Singapore, is heavily impacted by reclamation, dredging, construction and shipping. Tin, lead, nickel, cadmium, copper and zinc in the particulate and dissolved fraction and in sediments were monitored biweekly in the estuary from July 1999 to June 2000. The concentrations of tin, lead, nickel, cadmium, copper and zinc were observed to range from ND-92 ppm, ND-303 ppm, ND-2818 ppm, ND-74 ppm, ND-1117 ppm and ND-137000 ppm, respectively, in the dissolved, particulate and sediments fractions. Intensive dredging activity occurred during the monitoring period, and this may have led to the resuspension and increased bioavailability of particulate metals. Periphytic algae were established on glass slides and exposed to previously measured environmental levels of heavy metals using in situ estuarine microcosms. The toxicity of heavy metals in various fractions to periphytic algae was assessed from the changes in their chlorophyll a content. Cadmium had the least significant effect followed by lead, zinc, nickel, tin and copper at all concentrations tested. A reduction in periphyton biomass (with respect to controls) of 95-100% was observed for treatments with metals in particulate form. In addition, exposure to contaminated sediments for 3 days significantly decreased chlorophyll a by 90-99% compared to controls. High concentrations of zinc (9893-17240 mg l(-1)), copper (5-11 mg l(-1)) and cadmium (1-1.8 mg l(-1)) recorded in the aqueous phase of treatment microcosms, and attributed to release from the contaminated sediments, could account for the toxicity to periphyton.

UDP-galactose 4-epimerase from Escherichia coli: equilibrium unfolding studies

UDP-galactose 4-epimerase from Escherichia coli is a homodimer of 39 kDa subunit with non-covalently bound NAD acting as cofactor. The enzyme can be reversibly reactivated after denaturation and dissociation using 8 M urea at pH 7.0. There is a strong affinity between the cofactor and the refolded molecule as no extraneous NAD is required for its reactivation. Results from equilibrium denaturation using parameters like catalytic activity, circular-dichroism, fluorescence emission (both intrinsic and with extraneous fluorophore 1-aniline 8-naphthalene sulphonic acid), 'reductive inhibition' (associated with orientation of NAD on the native enzyme surface), elution profile from size-exclusion HPLC and light scattering have been compiled here. These show that inactivation, integrity of secondary, tertiary and quaternary structures have different transition mid-points suggestive of non-cooperative transition. The unfolding process may be broadly resolved into three parts: an active dimeric holoenzyme with 50% of its original secondary structure at 2.5 M urea; an active monomeric holoenzyme at 3 M urea with only 40% of secondary structure and finally further denaturation by 6 M urea leads to an inactive equilibrium unfolded state with only 20% of residual secondary structure. Thermodynamical parameters associated with some transitions have been quantitated. The results have been discussed with the X-ray crystallographic structure of the enzyme.

Prevalence of sputum-positive pulmonary tuberculosis in tribal and non-tribal populations of the Ashti and Karanja tahsils in Wardha district, Maharashtra State, India

SETTING

Ashti and Karanja tahsils, Wardha district, Maharashtra State, Central India.

OBJECTIVE

To find and compare the prevalence of bacillary positive pulmonary tuberculosis amongst the different tribes and in the non-tribal population.

DESIGN

Prevalence study of pulmonary tuberculosis by house-to-house survey of symptoms among tribal (n = 20596) and non-tribal (n = 93 670) populations aged 5 years and over, between September 1989 and November 1990.

RESULTS

The prevalence of smear and/or culture-positive tuberculosis/100000 population was 133 in the tribal and 144 in the non-tribal population. The difference in prevalence of symptomatic individuals and sputum-positive cases among the tribal and the non-tribal populations was statistically significant only in the symptomatic individuals/100000 (P = 0.01). The prevalence of cases in both groups was higher in males than females; however this difference was significant only in the tribal group (P = 0.05). Only two of the 46 tribes encountered, the Mana and Pawara tribes, showed a high prevalence, of 730 and 612/100000, respectively. The three other tribes with positive cases (the Gond group) had prevalences comparable to that of the nontribal population.

CONCLUSION

The prevalence of tuberculosis in tribal people was comparable to that of the non-tribal population.