Variation in urban snow quality indicated by three seasonal sampling surveys conducted in Luleå (Sweden) within a span of 27 years

Concentrations of total suspended solids (TSS), trace metals (Cu, Cd, Cr, Zn, Cd, Pb), Na and 16 US EPA priority PAHs in urban snow were studied in the City of Luleå in Northern Sweden. Snow was sampled at six central urban and suburban sites with various traffic intensities, in three sampling surveys (1994-95, 2002-03, 2020-21), repeated for three ages of the urban snow cover of 40, 80, and 120 days, respectively. The older data, from the 1994-95 and 2002-03 surveys, were obtained from the existing literature. The concentrations and mass loads of TSS and most trace metals studied (Zn, Cu, Pb, and Cd) varied with time. TSS, Zn, and Cu showed slightly higher concentrations and mass loads in the 2003 (TSS avg = 2300 μg/L, Zn avg = 620 μg/L and Cu avg = 250 μg/L) and 2021 (TSS avg = 1500 μg/L, Zn avg = 530 μg/L and Cu avg = 220 μg/L) sampling surveys, compared to the 1995 survey (TSS avg = 620 μg/L, Zn avg = 240 μg/L and Cu avg = 97 μg/L). However, no evident trend was observed between the 2003 and 2021 sampling surveys. The highest concentrations of Pb and Cd were observed in snow samples from the 1994-95 sampling survey (Pb max = 570 μg/L, Cd max = 4.6 μg/L). Results indicated higher concentrations of the pollutants studied in the city centre, compared to the residential suburbs, and in areas with heavier traffic, where concentrations of metals correlated well with traffic intensity. Fractionation analysis of trace metals indicated that Zn, Cu and Pb occurred mostly in the particulate-bound phase (>0.45 μm) containing the most of Zn, Cu, and Pb mass, at 80, 84 and 94% of the total, respectively. Over 50% of the dissolved phase of Zn and Cu was in the truly dissolved fraction (<3000 MWCO). Concentrations of PAHs also increased with traffic intensity, with pyrene being the most frequently detected PAH, likely because of the strength of sources and various physical processes influencing the snowbanks development and causing spatial and temporal variations in pollutant concentrations.

LB0003 WITHDRAWING METHOTREXATE AFTER BOTH VERSUS ONLY SECOND DOSE OF THE ChAdOx1 nCoV-19 VACCINE IN PATIENTS WITH AUTOIMMUNE INFLAMMATORY ARTHRITIS: TWO INDEPENDENT RANDOMIZED CONTROLLED TRIALS (MIVAC I AND II)

Background

Pausing methotrexate (MTX) for two to four weeks, improved immunogenicity of influenza vaccination in patients with rheumatoid arthritis (RA), albeit a risk of disease flare (1). This guided the framing of guidelines on MTX withdrawal for COVID-19 vaccination (2). However, evidence for MTX withdrawal for COVID-19 vaccination is limited to observational studies only.

Objectives

To compare the efficacy and safety of holding MTX after each (MIVAC 1) and only after the second dose (MIVAC II) of the ChAdOx1 vaccine versus continuation of MTX in two randomized controlled trials (RCTs).

Methods

Two single centre, investigator-blinded, RCTs were conducted in patients with RA or Psoriatic arthritis (PsA) on stable doses of MTX without prior COVID-19 (CTRI reg. no. MIVAC I: CTRI/2021/07/03463 & MIVAC II: CTRI/2021/07/035307). In MIVAC I, unvaccinated patients were randomised (1:1) to hold or continue MTX for two weeks after each dose of the vaccine. MIVAC II included patients who had continued MTX during the first dose of ChAdOx1 and were randomised (1:1) to hold or continue MTX for 2 weeks after the second vaccine dose. The primary outcome for both the trials was the anti-Receptor Binding Domain (RBD) antibody titres measured four weeks after the second vaccine dose (per protocol analysis). Secondary outcome was the flare rate, defined as an increase in disease activity scores (DAS28/cDAPSA) or physician intent to hike DMARDs.

Results

250 patients were randomized for MIVAC 1 and 178 for MIVAC II and after due exclusions, 158 and 157 were eligible for analysis respectively (Figure 1). In MIVAC I, median anti-RBD titres were significantly high in the MTX hold group [2484 (1050-4388) versus 1147(433-2360), p=0.001] but the flare rate was higher in the hold group [20 (25%) versus 6(8%) p=0.005] compared to continue group. In MIVAC II median anti-RBD titres were significantly high for the MTX hold group [2553 (1792-4823) versus 990 (356-2252), p=0.001] when compared to continue group but there was no difference in the flare rate between the groups [9(11.8%) and 4(7.9%), p=0.15] (Table 1). Since both were parallel studies in similar population, MTX hold arms across both the trials were compared for anti-RBD titres and flare. There was no difference in the anti-RBD titres [p=0.2] between the groups. In MIVAC I, 29(36.25%) patients had reported flare (19 in either first or second dose, 10 for both doses) when compared to MIVAC II where only 9(11.84%) patients had reported flare after the second dose (P <0.001).

Table 1.

Baseline demographics and key results

VariableMIVAC IMIVAC IIMTX HoldMTX ContinuePMTX HoldMTX ContinueP valueN=80N=78valueN=76N=81Age†48 (38-53.3)49 (39-59)0.1953 (42.3-59)53(50-62)0.14Female (%) ‡73 (91.3)75 (96.2)0.3365 (85.5)70 (86.4)>0.99RA (%) ‡69(86.3)69 (93.2)70 (85.6)80 (87.7)PsA (%) ‡11(13.8)6 (8.1)0.316 (7.9)1 (1.2)0.057DAS28†2.7 (2.4-3.2)2.6 (2-3.3)0.62.7(2.3-3.4)2.8 (2.1-3.5)0.78cDAPSA †2(3-4.5)2.5(1.3-3.8)0.463(2.8-3)30.15Prednisolone (%) ‡29 (36.3)23(31.1)0.424(31.6)26 (32.1)>0.99MTX mg/week†17.5 (10-25)15 (10-20)0.05715 (9.4-25)17.5(7.5-25)0.92Anti- RBD antibody titres post second dose (IU/mL) †2484 (1050-4388.8)1147.5 (433.5-2360.3)<0.0012553.5 (1792.5-4823.8)990.5 (356.1-2252.5)<0.001Flare (N%) ‡Post first dose20 (25)6 (8)0.005NANAPost second dose19 (23.8)10(13.3)0.19 (11.8)4 (7.9)0.15

All analysis as per protocol population.

†Median (interquartile range): Mann Whitney U test.

‡ N (%): Fisher Exact test

. Bolded if p<0.05.

Conclusion

Holding MTX after both the doses or only after the second dose of ChAdOx1 yields higher anti-RBD antibody titres as compared to continuing MTX. Comparing across the trials, holding MTX only after the second dose appears to be non-inferior to holding MTX after both doses of the vaccine with a lesser risk of flare.

References

[1]Park JK et al. Clin Rheumatol. 2020 Feb; 39(2):375-379.

[2]Curtis JR, et al. Arthritis & Rheumatology. 2021 Oct;73(10): e60-75.

Acknowledgements

Acknowledgments to all participating investigators, patients and their families

Disclosure of Interests

Anu Sreekanth: None declared, Teny Skaria: None declared, Sneha Joseph: None declared, Rashwith Umesh: None declared, Manju Mohanan: None declared, Aby Paul: None declared, Sakir Ahmed Speakers bureau: Sakir Ahmed had received honorarium as speaker from Pfizer, Dr Reddy’s, Cipla, and Novartis unrelated to this Comment, Pankti Mehta: None declared, Seena Oomen: None declared, Janet Benny: None declared, Justin George: None declared, Anagha Paulose: None declared, K Narayanan: None declared, Sanjana Joseph: None declared, Anuroopa Vijayan: None declared, Kaveri Nalianda: None declared, Padmanabha Shenoy: None declared

Chronic pain and its impact on quality of life following a traumatic rib fracture

PURPOSE

Traumatic rib fractures account for 7-40 % of trauma admissions and most of them heal spontaneously and do not contribute to disability. The prevalence of chronic pain and its impact on quality of life following a traumatic rib fracture has not been studied adequately.

METHODS

A retrospective review of electronic medical records of all the traumatic rib fracture admissions from January 2007 to December 2008 was conducted. This was followed up with a brief telephonic survey of the following questions: (1) Do you have pain following the trauma? (2) If YES, how severe is your pain from a score of zero to ten? (3) Does the pain affect your life style? (4) Does the pain affect your work? (5) Do you need to take regular pain medications?

RESULTS

One hundred and two patients responded to the survey and 23 patients (22.5 %) complained of chronic persistent pain. In patients with pain, six patients (26 %) had chronic pain that required regular use of analgesics, eight patients (35 %) complained of impairment of work life, and three patients (13 %) complained of impairment of personal quality of life. Chronic pain was not related to age, number of ribs fractured, flail chest, hemothorax and/or pneumothorax, chest tube insertion, or Injury Severity Score (ISS).

CONCLUSION

This study confirms the high incidence of chronic pain after a traumatic rib fracture. While the majority of the patients can manage this pain without interference of their quality of life, a few do suffer from life style/work interference and may have to resort to regular analgesic usage.

The impact of tax policies on living organ donations in the United States

In an effort to increase living organ donation, fifteen states passed tax deductions and one a tax credit to help defray potential medical, lodging and wage loss costs between 2004 and 2008. To assess the impact of these policies on living donation rates, we used a differences-in-differences strategy that compares the pre- and postlegislation change in living donations in states that passed legislation against the same change in those states that did not. We found no statistically significant effect of these tax policies on donation rates. Furthermore, we found no evidence of any lagged effects, differential impacts by gender, race or donor relationship, or impacts on deceased donation. Possible hypotheses to explain our findings are: the cash value of the tax deduction may be too low to defray costs faced by donors, lack of public awareness about the existence of these policies, and that states that were proactive enough to pass tax policy laws may have already depleted donor pools with previous interventions.

Management of isolated splenic injuries after blunt trauma: an institution's experience over 6 years

Forty-two patients with traumatic blunt splenic injuries were admitted over a six year period. Vehicular-related collisions and fall from height accounted for the injuries in 38 (90.5%) of them. Eleven (26.2%) underwent immediate surgery (7 splenectomy and 4 splenorrhaphy), while the remaining 31 patients were treated nonoperatively of which 3 underwent angio-embolisation. Twenty seven patients had either grade III or IV splenic injuries. Operative management was more likely in patients with lower haemoglobin or with more severe splenic injury. Nonoperative management can be adopted in patients with blunt isolated splenic injuries but operative management is still indispensable in certain instances.

Management of diaphragmatic rupture from blunt trauma

INTRODUCTION

Diagnosis of diaphragmatic rupture is difficult, and delays could result in a catastrophic outcome. We reviewed our institution's management of patients with diaphragmatic rupture after blunt trauma.

METHODS

All patients in this study were treated at Tan Tock Seng Hospital, Singapore, from March 2002 to October 2008. Patients with penetrating injuries were excluded. The parameters included age, mechanism of injury, haemodynamic status at admission, Glasgow coma scale (GCS) score, injury severity score (ISS), imaging studies, location of diaphragmatic injuries, associated injuries and outcome.

RESULTS

14 patients with a median age of 38 years formed the study group. Vehicular-related incidents accounted for 71.4 percent of the injuries. The median GCS score on admission was 14 (range 3-15), while the median systolic blood pressure and heart rate were 94 (range 50-164) mmHg and 110 (range 76-140) beats per minute, respectively. The median ISS was 41 (range 14-66). All had chest radiographs performed in the emergency department, six (42.9 percent) had computed tomography performed before surgery, while the remaining eight (57.1 percent) were sent straight to the operating theatre from the emergency department. There were five (35.7 percent) right-sided and nine (64.3 percent) left-sided diaphragmatic ruptures. The mortality rate was 35.7 percent. Some of the associated injuries included eight (57.1 percent) splenic lacerations, five (35.7 percent) haemothorax and lung injuries, four (28.6 percent) bone fractures and three (21.4 percent) liver lacerations. 12 (85.7 percent) patients underwent repair of the diaphragmatic rupture using interrupted polypropylene suture, while the remaining two (14.3 percent) were too haemodynamically unstable to undergo definitive treatment. Advanced age, haemodynamic instability and raised ISS were associated with mortality.

CONCLUSION

An accurate diagnosis of diaphragmatic rupture in trauma patients is difficult, and a thorough examination of both the hemidiaphragms is mandatory during emergency laparotomy for these patients. Those with more severe injuries and decreased physiological reserves usually fare worse.

Altruistic living donors: evaluation for nondirected kidney or liver donation

A program was established within our regional procurement organization to permit evaluation of altruistic living donors (LD) interested in nondirected kidney or liver segment donation prior to transplant center referral. During the initial 30 months of program operations, 731 donor inquiries were received of which 131 individuals called back after review of mailed information materials. Forty-seven candidates initiated and 19 completed the evaluation process. Seven underwent donation to include six kidneys and one liver segment, five are actively pending donation, five were excluded from donation following transplant center evaluation and two took no further action after their intended liver recipients received deceased donor (DD) transplants. Psychological evaluation of these 19 candidates found them to be free of psychopathology, highly cooperative and self-directed. They did not exhibit attention-seeking or religious motivations for their actions. All seven donors and recipients continue to do well postoperatively. This evaluation program has made possible large-scale screening and education of prospective altruistic LD within the general population and also provides a unique opportunity to further our understanding of those individuals interested in living-nondirected donation.

An intelligent tutoring system for trauma management (Trauma-Teach): a preliminary report

Trauma-Teach is an interactive software for tutoring surgical trainees on medical trauma management procedures. Users of the system interact with a virtual patient suffering from trauma injuries. The task of the user is to stabilise the virtual patient, discover the underlying injuries and decide on an appropriate management plan. Artificial intelligence techniques are used to simulate the patient's pulmonary and cardiovascular systems in real time, determine the responses and results of treatments and diagnostics accordingly, model the patient deterioration if wrong actions are taken, and give a measure of reality to the system by selecting actual trauma cases from the hospital's database.

Management delays for early gastric cancer in a country without mass screening

BACKGROUND/AIMS

To examine the symptoms of early gastric cancer and the time scale of management delays in a country without a mass screening program.

METHODOLOGY

Retrospective review of 44 patients with early gastric cancer.

RESULTS

Epigastric pain (63.3%) and gastrointestinal hemorrhage (27.3%) were the main symptoms found. Total delay was made up of patient delay (48.6%), doctor delay (25.5%) and treatment delay (25.9%). Median patient delay (from symptom onset to medical consult) was 30 days (inter-quartile range 2 to 365). Patient delay of more than 6 months was associated with patients aged 50 and younger (P = 0.04) and those presenting with pain (P = 0.05). Median doctor delay (consult to diagnosis) was 21 days (1 to 35) and median treatment delay (diagnosis to surgery) was 8 days (2 to 21). Doctor delay of more than 6 months was associated with a negative gastroscopy or barium meal in the previous 12 months (P = 0.03).

CONCLUSIONS

The detection of early gastric cancer at the symptomatic-detectable stage is possible and this potential window for diagnosis can be more than 1 year for up to one third of cases. Efforts to reduce management delays should be aimed at public education and improving the quality and accessibility of endoscopic evaluation.

Hepatocyte growth factor inhibits apoptosis after ischemic renal injury in rats

Several studies have determined that growth factors, including hepatocyte growth factor (HGF), have a crucial role in the regenerative process of renal tubules after ischemic or toxic insult. Recent research has ascertained that as well as necrotic cell death, there is evidence of apoptosis after an acute renal injury. We attempted to determine the effect of HGF on apoptosis after ischemic renal injury in rats. We administered HGF or vehicle to 12 rats after ischemic insult and compared them with 6 sham-operated controls. Rats were killed at 48 hours, and histopathologic assessments were performed on the renal tissue. The microscale autoradiographic method was used for qualitative analysis of DNA fragmentation. This method was chosen over the widely used ethidium bromide-staining method because it increases the sensitivity of detection of apoptotic DNA. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling histopathologic staining was used to identify apoptosis in situ. Apoptotic changes were clearly shown by electron microscopy in vehicle-treated animals. Despite showing profound evidence of tubular necrosis, apoptotic changes were markedly reduced in HGF-treated animals compared with vehicle-treated animals. DNA-laddering analysis further confirmed the antiapoptotic effect of HGF. To our knowledge, this is the first in vivo illustration of the inhibitory activity of a growth factor on apoptosis in the setting of tubular necrosis. The role of apoptosis in the setting of acute renal failure has not been elucidated; thus, additional research is necessary to determine the significance of these findings.

Elevated blood pressure in men accompanying patients to the obstetrician's office

Hypertension is common and leads to increased mortality among adults; yet, one-third of hypertensive adults in the United States are unaware of their condition. The purpose of this study was to determine the frequency of unrecognized elevated blood pressure (BP) in men accompanying pregnant women to the obstetrician's office. Blood pressure measurements were offered to men accompanying pregnant women to four obstetrics practices in St. Louis, Missouri. Age, race, history of hypertension, and relationship to the pregnant woman were also recorded. A total of 191 men participated in the study. Participants' ages ranged from 15 to 69 years, with a mean of 27 years. Elevated BP (> 140/90 mm Hg) was detected in 40 men (21%). Only 5% of men with an elevated BP were aware of a prior history of elevated BP. We conclude that the obstetrician's office provides a good opportunity for initial screening for hypertension in men. Follow-up is necessary to determine the accuracy of the diagnosis.

Clinical use of growth factors in chronic renal failure

Erythropoietin has been demonstrated to improve the quality of life in patients with chronic renal failure, and growth hormone has been approved for use in children with chronic renal failure and short stature as a growth promoting agent. Growth factors also have great therapeutic potential to improve glomerular function in the setting of chronic renal failure. Further studies are required to delineate the role of insulin-like growth factor I in the setting of end-stage chronic renal failure.

Insulin-like growth factor 1 enhances renal function in a patient with chronic renal failure on peritoneal dialysis

Insulin-like growth factor 1 (IGF1) has been shown to improve renal function in healthy subjects, as well as those with chronic renal failure. To our knowledge, IGF1 has not been shown to be efficacious in patients who were already undergoing dialysis. We present the case of a 70-year-old woman with end-stage renal disease (ESRD) and overt uremic symptoms treated with IGF1 after peritoneal dialysis was discontinued because of complications. There was a significant improvement in her inulin clearance during the course of treatment. The patient remained well and did not require dialytic support for 19 weeks. Although further data are necessary, we believe this case shows that IGF1 may be a short-term alternative to dialysis in patients with ESRD.

Insulin-like growth factor I improves renal function in patients with end-stage chronic renal failure

There is no pharmacological treatment to increase the glomerular filtration rate in end-stage renal disease (ESRD). The administration of 100 microgram/kg of insulin-like growth factor (IGF) I twice a day to patients with ESRD increases inulin clearance. However, its effect is short-lived and IGF-I has major side effects when given this way. To assess whether the use of a lower intermittent dose of IGF-I would effect sustained improved function with tolerable side effects we performed 1) a prospective open-labeled 24-day trial in which we enrolled five patients and 2) a 31-day randomized, double-blinded, placebo-controlled trial in which we enrolled 10 patients. Patients with ESRD [creatinine clearance of <15 ml. min-1. (1.73 m2)-1] and scheduled to initiate renal replacement therapy received subcutaneous IGF-I, 50 microgram. kg-1. day-1, or vehicle. Treatment with IGF I resulted in significantly increased glomerular filtration rates (inulin clearances) during the 3rd and 4th wk of therapy in both prospective and double-blinded studies. Vehicle had no effect. No patient required discontinuation of drug secondary to side effects. We conclude that IGF-I effects sustained improvement of renal function (clearances comparable to those generally achieved by dialysis) in patients with ESRD and is well tolerated.

Recombinant human insulin-like growth factor-I (IGF-I) therapy decreases plasma leptin concentration in patients with chronic renal insufficiency

OBJECTIVE

To determine the relationship between plasma leptin and insulin-like growth factor-I (IGF-I) levels in healthy subjects and patients with chronic renal insufficiency at baseline, and during administration of recombinant human IGF-I in the renal impaired patients.

SUBJECTS

20 healthy subjects (six men, 14 women, age: 42.7 +/- 3.2 y) and nine subjects with chronic renal insufficiency (five men, four women, age: 53.6 +/- 3.7 y).

INTERVENTION

Daily s.c. injection of recombinant human IGF-I (50 micrograms/kg) for 24 d.

MEASUREMENTS

Fasting plasma levels of leptin, IGF-I, growth hormone, C-peptide, glucagon and IGF binding proteins by specific radioimmunoassays at baseline in all subjects and serially during IGF-I therapy in the renal impaired subjects.

RESULTS

Baseline leptin levels were correlated with body mass index (BMI, R = 0.72, P = 0.0001) but not IGF-I levels (R = 0.02). During IGF-I therapy, plasma IGF-I levels increased from 128 +/- 17.4 ng/ml at baseline to 250 +/- 36.8 ng/ml on day 3 (P = 0.003) and 323 +/- 61.6 ng/ml on day 24 (P = 0.01), whereas leptin levels declined: 24.4 +/- 10.3 ng/ml (baseline), 19.5 +/- 6.2 ng/ml (day 3, P = 0.028), and 17.2 +/- 4.9 ng/ml (day 24, P = 0.05).

CONCLUSION

Basal plasma leptin and IGF-I levels are not correlated; however, chronic administration of recombinant IGF-I is associated with an early and sustained decrease in plasma leptin levels. IGF-I may have an inhibitory effect on leptin secretion in humans.

Acute renal failure: prevention and nondialytic therapy

Acute renal failure (ARF) is a common illness with significant associated mortality and morbidity. Despite the advent of renal replacement therapy and the advancement in dialytic technology, the mortality of ARF has not significantly changed in the last 30 years. The cost of treating acute renal failure with the available therapies inflicts a tremendous financial burden on the health care system. The majority of patients with acute renal failure have multiple etiologies which are frequently iatrogenic. Physicians frequently underestimate the level of renal dysfunction in patients and therefore interventions to curb or treat renal failure are delayed. It is clear that ARF can be averted with more vigilance and early interventions. No pharmacological agent has yet been approved for the treatment of acute renal failure. Several substances are in the various stages of animal and human trials. Until one becomes available for use in the treatment of renal failure, it is clear that prevention is the principal element in the management of ARF. The purpose of this review is to discuss the various risk factors for acute renal failure, methods of prevention, and pharmacological interventions that may be beneficial in the treatment of ARF.

On the notion of a "subtle phonetic deficit" in fluent/posterior aphasia

Phonetic investigations in the past decade or so have reported instances of a "subtle phonetic deficit" in the fluent aphasias, thereby challenging the traditional dichotomy of a motoric deficit characterizing the nonfluent aphasias and a selection deficit characterizing the fluent aphasias. This paper critically reviews the acoustic, physiological, and perceptual studies which have attempted to examine this phenomenon. These investigations have been evaluated in terms of differences in subject populations, task demands, subjects' performance, and problematic interpretations. Suggestions are offered for an experimental design which can help us operationalize this term and help us to better understand the speech production deficit in fluent aphasic patients.

Effects of sleep deprivation on performance of Naval seamen: I. Total sleep deprivation on performance

Sleep deprivation leads to impairment in performance, loss of efficiency and deterioration in mood states such as tension, depression, aggression, fatigue, confusion and vigour. These can be detrimental to combat readiness and could contribute to "battle stress". In the present study, a homogeneous group of 20 seamen under total sleep deprivation was rated 6 hourly with the Stanford Sleepiness Scale (SSS), Profile of Mood States (POMS) and a battery of performance tests including the trail making, grooved peg board, digit span, digit symbol, sea-shore rhythm, flicker fusion, dynamometer and naval tasks. With the exception of the trail making test and naval tasks, the test performance was observed to correlate significantly (P < 0.05) with the SSS. A higher sleepiness score was associated with a poorer performance in test scores. On the time trends of sleep deprivation on the performance tests measured, a dip in performance was observed in all the tests at 42 hours of sleep deprivation and continuous deterioration of performance was observed after 72 hours of sleep deprivation. The cognitive, vigilance, mood and sleepiness tests were substantially affected by sleep deprivation. Greater effect was observed in tests that involved cognition, speed and precision and smaller effect was observed in routine tasks that involved gross manual movement. The decrease in performance observed at 42 hours of sleep deprivation was 5.9 standard deviation from initial values for SSS; 3.9 for sea-shore rhythm, 3.0 for grooved peg board; 2.6 for dynamometer; 2.4 for mood; 1.8 for digit span; 1.6 for trail making and digit symbol; 1.0 for naval tasks and addition; and 0.9 for flicker fusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sleep deprivation on naval seamen: II. Short recovery sleep on performance

Twenty male naval volunteers, aged 18 to 20 years, with 12 to 14 years of education, underwent a total sleep deprivation experiment on board a Republic of Singapore Navy landing ship in the South China Sea for a period of 42-102 hours. The sleep group comprised eight volunteers who dropped out at the 44th-46th h of the experiment and were randomly assigned to a 2 or 4 h sleep regime. The rest served as sleep-deprived controls. Neurobehavioural performance tests, profile of mood state and the Stanford Sleepiness Scale were applied 6 hourly starting from 6.00 am on the first experimental day. No thresholds were observed in the performance of tests related to manual tasks and subjective feeling, including naval tasks, mood and sleepiness scale during the sleep deprivation experiment. However, thresholds were observed in the performance of tests requiring cognitive and perceptive skills, including the grooved peg board, trail making, sea-shore rhythm, addition, digit span, digit symbol, flicker fusion and dynamometer tests. Performances in these tests were observed to deteriorate only after approximately 30 h of sleep deprivation. The Z score for the non-threshold tests (Z-N) deteriorated from -0.01 at the start of the experiment to 1.25 at the 42nd h of the experiment just before the imposed sleep and improved to 0.81 at the 48th h of the experiment just after the imposed sleep; and the Z score for the threshold tests (Z-T) varied from -0.07 at the start to 0.49 just before sleep (at the 42nd h) and to continuously deteriorate to 0.83 just after sleep (at the 48th h).(ABSTRACT TRUNCATED AT 250 WORDS)

Decompression sickness in the Singapore Mass Rapid Transit Project

In the Singapore Mass Rapid Transit Project (MRT), 11 km of underground tunnels were built using compressed air. 1,737 compressed air workers (CAWs) were employed in the project. They underwent 188,538 man decompressions at the various compressed air worksites. 160 CAWs developed Type I decompression sickness (DCS) and 4 developed Type II DCS. This gave an overall incidence of 0.087%. The adoption of strict medical selection, strict adherence to decompression procedures and the provision for acclimatization of newstarters contributed greatly to this low incidence. Prompt treatment of DCS accounted for the low relapse rate. The clinical presentation of DCS is discussed here. Prevention of DCS by worksite environmental and work-practice monitoring are advocated.

Acute decompression sickness in compressed air workers exposed to pressures below 1 bar in the Singapore Mass Rapid Transit project

The Singapore Mass Rapid Transit (MRT) project started compressed air work in Oct 1984. Eleven km of underground tunnels out of 20 km were built using this method. Cases of decompression sickness (DCS) arising from compressed air work are rare with working pressures less than 1 bar gauge. However, there were 10 cases of DCS in the MRT project who were exposed to less than 1 bar pressure. The authors present their clinical features and attempt to explain the observations in relation to theories of bubble nuclei formation, gas loading and rate of decompression. The formation of bubble micronuclei are correlated with physical factors like heavy exertion, and the use of vibrating tools. The concept of extremely long tissue half-times in the absorption of nitrogen in the body is discussed as a contributory factor to the development of DCS under 1 bar.