Multi-Stage Group Testing Improves Efficiency of Large-Scale COVID-19 Screening.

BACKGROUND: SARS-CoV-2 test kits are in critical shortage in many countries. This limits large-scale population testing and hinders the effort to identify and isolate infected individuals. OBJECTIVE: Herein, we developed and evaluated multi-stage group testing schemes that test samples in groups of various pool sizes in multiple stages. Through this approach, groups of negative samples can be eliminated with a single test, avoiding the need for individual testing and achieving considerable savings of resources. STUDY DESIGN: We designed and parameterized various multi-stage testing schemes and compared their efficiency at different prevalence rates using computer simulations. RESULTS: We found that three-stage testing schemes with pool sizes of maximum 16 samples can test up to three and seven times as many individuals with the same number of test kits for prevalence rates of around 5% and 1%, respectively. We propose an adaptive approach, where the optimal testing scheme is selected based on the expected prevalence rate. CONCLUSION: These group testing schemes could lead to a major reduction in the number of testing kits required and help improve large-scale population testing in general and in the context of the current COVID-19 pandemic.

Is sarcopenia a better predictor of complications than body mass index? Sarcopenia and surgical outcomes in patients with rectal cancer.

AIM: Sarcopenia, or a reduction of lean muscle mass, is associated with poorer outcomes in cancer patients. Few previous studies have examined this potentially correctable risk factor in patients with locally advanced rectal cancer. METHOD: Skeletal muscle mass index was measured retrospectively on initial staging CT scans of patients undergoing chemoradiation followed by radical resection for rectal cancer for the period 2007-2013. Patients were categorized as sarcopenic or nonsarcopenic and differences in terms of demographics, pre-, peri- and postoperative outcomes were examined. RESULTS: Forty-seven patients were included; their mean age was 59.3 (36-82) years and 61.7% were men. We considered that 55.2% of men and 44.4% of women were sarcopenic; the overall prevalence of sarcopenia was 51.1%. Age, preoperative haemoglobin and albumin were significantly related to sarcopenia. Body mass index (BMI) and obesity (BMI > 30 kg/m2 ) were not associated with sarcopenia. Blood transfusions were more frequent in sarcopenic patients (P = 0.001). Although readmissions and length of stay were not increased, overall postoperative complications were significantly higher in sarcopenic patients (P = 0.03). Neither BMI nor obesity was associated with postoperative complications. CONCLUSION: Sarcopenia was present in over 50% of patients with locally advanced rectal cancer at diagnosis. It was associated with a higher incidence of both blood transfusion and postoperative complications. BMI did not correlate with these negative outcomes. Sarcopenia may be a better predictor of surgical outcomes than BMI or obesity.

Fast neutron radiography scanner for the detection of contraband in air cargo containers.

There is a growing need to rapidly scan bulk air cargo for contraband such as illicit drugs and explosives. The Commonwealth Science and Industrial Research Organisation (CSIRO) have been working with Australian Customs Service to develop a scanner capable of directly scanning airfreight containers in 1--2 minutes without unpacking. The scanner combines fast neutron and gamma-ray radiography to provide high-resolution images that include information on material composition. A full-scale prototype scanner has been successfully tested in the laboratory and a commercial-scale scanner is due to be installed at Brisbane airport in 2005.

Fatal propofol infusion syndrome in association with ketogenic diet.

Propofol is used for the treatment of refractory status epilepticus. When given as a long-term infusion propofol may cause a rare but frequently fatal complication, the propofol infusion syndrome. The hallmarks are metabolic acidosis, lipemia, rhabdomyolysis and myocardial failure. Propofol infusion syndrome is caused by impaired fatty acid oxidation. Beside anticonvulsants the ketogenic diet, a high-fat, low-carbohydrate, adequate-protein diet, is an effective treatment for difficult-to-control seizures. We report a 10-year-old boy with catastrophic epilepsy, who developed fatal propofol infusion syndrome when a ketogenic diet was initiated. Substances like propofol which impair fatty acid oxidation may pose an increased risk if combined with ketogenic diet.

Interaction between weak low frequency magnetic fields and cell membranes.

The question of whether very weak low frequency magnetic fields can affect biological systems, has attracted attention by many research groups for quite some time. Still, today, the theoretical possibility of such an interaction is often questioned and the site of interaction in the cell is unknown. In the present study, the influence of extremely low frequency (ELF) magnetic fields on the transport of Ca(2+) was studied in a biological system consisting of highly purified plasma membrane vesicles. We tested two quantum mechanical theoretical models that assume that biologically active ions can be bound to a channel protein and influence the opening state of the channel. Vesicles were exposed for 30 min at 32 degrees C and the calcium efflux was studied using radioactive (45)Ca as a tracer. Static magnetic fields ranging from 27 to 37 micro T and time varying magnetic fields with frequencies between 7 and 72 Hz and amplitudes between 13 and 114 micro T (peak) were used. We show that suitable combinations of static and time varying magnetic fields directly interact with the Ca(2+) channel protein in the cell membrane, and we could quantitatively confirm the model proposed by Blanchard.

Differential responses in the fusiform region to same-race and other-race faces.

Many studies have shown that people remember faces of their own race better than faces of other races. We investigated the neural substrates of same-race memory superiority using functional MRI (fMRI). European-American (EA) and African-American (AA) males underwent fMRI while they viewed photographs of AA males, EA males and objects under intentional encoding conditions. Recognition memory was superior for same-race versus other-race faces. Individually defined areas in the fusiform region that responded preferentially to faces had greater response to same-race versus other-race faces. Across both groups, memory differences between same-race and other-race faces correlated with activation in left fusiform cortex and right parahippocampal and hippocampal areas. These results suggest that differential activation in fusiform regions contributes to same-race memory superiority.

Transparency effects on powder speckle decorrelation.

Laser speckle decorrelation has previously been applied to measure the mean powder size of bulk powder beds and the roughness of porous rocks. The angular decorrelation rate of laser speckle from bulk powder beds correlates strongly with the mean powder size. However it was found that the angular decorrelation rates of transparent powders were much higher than those of opaque or dyed powders of the same size distribution. The accuracy of size measurements could be severely compromised if transparency effects were not compensated. Monte Carlo modelling of remitted photon path lengths in a powder bed suggests and experimental data supports that diffuse reflectance data may be used to correct for transparency effects on angular decorrelation rate data.

Repeated immunotherapy using intratumoural injection with recombinant interleukin-2 and tumour-infiltrating lymphocytes inhibits growth of breast cancer and induces apoptosis of tumour cells.

This study tested the effect of repeated intratumoural injection with recombinant interleukin-2 (rIL-2) and tumour-infiltrating lymphocytes (TILs) on inhibition of growth of breast cancer and on induction of apoptosis of tumour cells. The tumour cell line LDLX43 was used to induce breast cancer in Wistar rats. Group I (10 rats) was the control. Group II (12 rats) received repeated intratumoural injection with rIL-2 and TILs. rIL-2 at the dose of 5 x 10(5) IU/day was given for 7 days, and 1 x 10(7) TILs were injected on the second day of each rIL-2 therapy, for a treatment session. Overall, two treatment sessions of immunotherapy with rIL-2 and TILs were given in all treated animals. Rapid increased tumour volume was found in the control group. In the treated group the total response rate was 42%, of which 25% tumours showed partial regression and 17% tumours reached complete remission where infiltration of plenty of T lymphocytes was detected, indicating that T cell-mediated antitumour immunity is primarily responsible for tumour rejection. Further investigation showed the repeated immunotherapy using intratumoural injection with rIL-2 and TILs could induce the development of apoptosis of breast cancer cells.

Somatostatin receptor scintigraphy in the staging of small cell lung cancer.

The aim of this study was to evaluate somatostatin receptor scintigraphy (SRS) in the staging of patients with small cell lung cancer. Prior to chemotherapy, 20 patients were investigated up to 24 h following an injection of 200 MBq 111In-octreotide. Following chemotherapy and restaging, four patients were re-evaluated. Primary tumour was detected in 18 of 23 studies, which exhibited increasing target-to-back-ground ratios over time. Lymph node metastases and distant metastases were detected in 7 of 27 and 8 of 31 sites, respectively. Thus, the overall sensitivity for detecting metastases was less than 26%. SRS did not result in any upstaging of patients. We conclude that in patients with small cell lung cancer, functional imaging by SRS has no impact on clinical decision making.

111In-octreotide imaging in patients with long-standing Graves' ophthalmopathy.

The aim of this study was to examine patients with long-standing Graves' ophthalmopathy using 111In-octreotide scintigraphy. Sixteen patients with inactive ophthalmopathy of up to 114 months duration and 14 normals were investigated for 48 h following an injection of 200 MBq 111In-octreotide. No significant tracer accumulation in the orbital region could be identified in any of the patients with long-standing Graves' ophthalmopathy. The orbit to brain (O/B) ratios after 24 and 48 h were 2.39 +/- 0.36 and 2.15 +/- 0.44 versus 2.17 +/- 0.33 and 2.20 +/- 0.37 for the patients and normals, respectively (N.S.). 111In-octreotide accumulation in ophthalmopathy described in the literature may thus be a passing event limited to its active stage, which is consistent with the concept of imaging a lymphocytic infiltration. In this study, the lack of accumulation of 111In-octreotide in the orbital region during the inactive stage demonstrates an absence of somatostatin receptors in orbital tissue itself. Thus, in patients with inactive Graves' ophthalmopathy, there is no basis for a diagnostic approach with somatostatin.

[DACS--a cost-advantageous nuclear medical document archiving and communication system]. / DACS--Ein kostengünstiges nuklearmedizinisches Dokumentenarchiv- und Kommunikationssystem.

A simple and inexpensive solution for the complete digital management of a nuclear medical institution is presented. The starting point was provided by five different gamma cameras, one of which was equipped with a PC-based ICON computer. The remaining cameras were first adapted to ICONs and subsequently integrated into a Macintosh LAN, of 15 computers, allowing the entire image acquisition, processing, interpretation, documentation and archiving to be performed on the same comfortable menu-guided surface. Complete patient management is accomplished by a specific commercially available data base to which a specially developed image and document archive was connected. The system described provides complete digital management without the conventional filing systems at the moderate price of approximately DM 11 x 10(4) plus the cost of the new camera computers.

Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz.

Biological effects of electromagnetic fields (EMF) on the blood-brain barrier (BBB) can be studied in sensitive and specific models. In a previous investigation of the permeability of the blood-brain barrier after exposure to the various EMF-components of proton magnetic resonance imaging (MRI), we found that the exposure to MRI induced leakage of Evans Blue labeled proteins normally not passing the BBB of rats [Salford et al. (1992), in: Resonance Phenomena in Biology, Oxford University Press, pp. 87-91]. In the present investigation we exposed male and female Fischer 344 rats in a transverse electromagnetic transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse-modulated with repetition rates of 8, 16, 50, and 200 s-1. The specific energy absorption rate (SAR) varied between 0.016 and 5 W/kg. The rats were not anesthetized during the 2-hour exposure. All animals were sacrificed by perfusion-fixation of the brains under chloral hydrate anesthesia about 1 hour after the exposure. The brains were perfused with saline for 3-4 minutes, and thereafter fixed in 4% formaldehyde for 5-6 minutes. Central coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 microns. Albumin and fibrinogen were demonstrated immunohistochemically. The results show albumin leakage in 5 of 62 of the controls and in 56 of 184 of the animals exposed to 915 MHz microwaves. Continuous wave resulted in 14 positive findings of 35, which differ significantly from the controls (P = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Attentional modulation of the phonetic significance of acoustic cues.

Four experiments addressing the role of attention in phonetic perception are reported. The first experiment shows that the relative importance of two cues to the voicing distinction changes when subjects must perform an arithmetic distractor task at the same time as identifying a speech stimulus. The contribution of voice onset time to phonetic labeling decreases when subjects are distracted, while that of FO onset frequency increases. The second experiment shows a similar pattern for two cues to the distinction between the vowels /i/ (as in "beat") and /I/ (as in "bit"). Under low attention conditions, formant pattern has a smaller effect on phonetic labeling while vowel duration has a larger effect. Together these experiments indicate that careful attention to speech perception is necessary for strong acoustic cues (voice-onset time and formant patterns) to achieve their full impact on phonetic labeling, while weaker acoustic cues (FO onset frequency and vowel duration) achieve their full impact on phonetic labeling without close attention. Experiment 3 shows that this pattern is obtained when the distractor task places little demand on verbal short-term memory. Experiment 4 provides a data set for testing formal models of the role of attention in speech perception. Attention is shown to influence the signal-to-noise ratio in the phonetic encoding of acoustic cues; the sustained phonetic contribution of weak cues without close attention stems from reduced competition from strong cues. This principle is instantiated in a network model in which the role of attention is to reduce noise in the phonetic encoding of acoustic cues. Implications of this work for understanding speech perception and general theories of the role of attention in perception are discussed.

A computed tomographic study of the distances between the maxillary sinus floor and the apices of the maxillary posterior teeth.

The mean distance between the apices of the maxillary posterior teeth and the floor of the maxillary sinus was measured from computed tomographic display data from 12 autopsy specimens and 38 human subjects. The distance from these apices to the adjacent lateral bony surfaces was also measured. The apex of the mesiobuccal root of the maxillary second molar was closest to the sinus floor (mean 1.97 mm) but farthest from the buccal bony surface (mean 4.45 mm). The apex of the buccal root of the maxillary first premolar was closest to the adjacent lateral bony surface (mean 1.63 mm) but farthest from the floor of the sinus (mean 7.05 mm).

Disease activity and joint damage progression in early rheumatoid arthritis: relation to IgG, IgA, and IgM rheumatoid factor.

The clinical and biochemical correlations with joint damage progression over two years in a consecutive group of 68 patients with rheumatoid arthritis with disease duration of less than two years are reported. Joint damage was assessed with Larsen's severity scale and a measure of change in progression rate constructed. Initial haemoglobin concentration, Ritchie index, and Waaler-Rose titre in combination accounted for one third of the variance in joint damage progression. Rheumatoid factor (RF) concentrations were followed with enzyme linked immunosorbent assays (ELISAs) for IgG RF, IgA RF, and IgM RF. The RF concentrations, except IgG RF, decreased with time; significant correlations between RFs and disease activity were few and barely clinically useful. After two years IgG RF correlated significantly with a radiological score if early non-erosive changes were omitted. All RFs tended to correlate better with this radiological score at all three observation points. Analyses of the change in progression rate indicated a time delay between development of radiographic changes and increase of IgG RF. These results suggest an indirect relation between RFs and joint damage. Clinical and biochemical improvements in early RA occur despite joint damage progression, and conventional markers have insufficient predictive value.

Sleep disturbances caused by vibrations from heavy road traffic.

The influence of whole-body vibrations, noise, and a combination of the two, caused by heavy road traffic (150 events/night) on sleep, subjectively experienced sleep quality, and performance was investigated under controlled laboratory conditions for male and female subjects 20-35 years of age. A room was built above a vibrator table, with the legs of the bed mounted directly on the table through holes in the floor. Vertical vibrations were found to be attenuated by the mattress with 20-40 dB for frequencies greater than 10 Hz, whereas horizontal vibrations were slightly amplified. It could be concluded that when traffic noise [50-dB (A) peak level] is accompanied by vibrations with peak levels of 0.24 m/s2 vertically and 0.17 m/s2 horizontally as measured on the frame of the bed (stimulus duration approximately 2 s, dominant frequency approximately 12 Hz), sleep is more disturbed than is the case when noise alone occurs. The amount of REM sleep, which was significantly reduced for the vibration level mentioned above, was even more disturbed when a higher exposure level, 0.34 m/s2 vertically and 0.24 m/s2 horizontally, was applied. The subjectively rated sleep quality was lower for the higher than for the lower vibration level. Performance in the morning was only influenced for the higher vibration level. It could be concluded that vibration exposure levels near the recommendation made in ISO-standard 2631 for the awake state disturb sleep in man.

Carbon dioxide laser tuning through 110 lines in 3 ms for airborne remote sensing.

Rapid tuning of a 3-m long glow discharge excited CO(2) laser is achieved by a rotating polygonal mirror scanning the intracavity beam across a diffraction grating. The system can tune through 110 different rotational lines spanning wavelengths from 9.2 to 11.1 microm in 3 ms with typical peak powers of 100-500 W at burst repetition rates up to 360 Hz and is suitable for airborne remote sensing. The effects of laser output coupler reflectance, burst rate, scan direction, and current modulation are investigated, and the performance of an optimized system for mineral reflectance measurements is presented. A reflection spectrum of a shale obtained with the rapidly tuned laser at a range of 5 m is shown to compare well to data gathered for the same sample using a slowly tuned cw CO(2) laser.

The effect of ambient ozone pollution and acidic rain on the growth and chlorophyll content of green and white ash.

Two- and three-year old green ash (Fraxinus americana L.) and white ash (Fraxinus pennsylvanica Marsh.) seedlings were exposed to combinations of ambient ozone and acidic ambient rainfall in New Brunswick, New Jersey. During the 3-year study the potted seedlings did not develop typical foliar ozone toxicity symptoms, despite the occurrence of as many as 78 h in exceedance of the National Ambient Air Quality Standard of 0.12 ppm. Although the pH of the rainfall was as low as 3.6 and averaged 4.1, no symptoms were observed resulting from the ambient precipitation. The rate of shoot growth in terms of height and diameter was generally not affected by either of the pollutants during the growing season. Although the chlorophyll content of white ash foliage was low following frequent rainfall in the early summer of 1984, there was no statistically significant evidence that acid raid or ambient ozone decreased chlorophyll in ash seedlings during the 3-year study.