Probabilistic predictions of SIS epidemics on networks based on population-level observations.

We predict the future course of ongoing susceptible-infected-susceptible (SIS) epidemics on regular, Erdos-Rényi and Barabási-Albert networks. It is known that the contact network influences the spread of an epidemic within a population. Therefore, observations of an epidemic, in this case at the population-level, contain information about the underlying network. This information, in turn, is useful for predicting the future course of an ongoing epidemic. To exploit this in a prediction framework, the exact high-dimensional stochastic model of an SIS epidemic on a network is approximated by a lower-dimensional surrogate model. The surrogate model is based on a birth-and-death process; the effect of the underlying network is described by a parametric model for the birth rates. We demonstrate empirically that the surrogate model captures the intrinsic stochasticity of the epidemic once it reaches a point from which it will not die out. Bayesian parameter inference allows for uncertainty about the model parameters and the class of the underlying network to be incorporated directly into probabilistic predictions. An evaluation of a number of scenarios shows that in most cases the resulting prediction intervals adequately quantify the prediction uncertainty. As long as the population-level data is available over a long-enough period, even if not sampled frequently, the model leads to excellent predictions where the underlying network is correctly identified and prediction uncertainty mainly reflects the intrinsic stochasticity of the spreading epidemic. For predictions inferred from shorter observational periods, uncertainty about parameters and network class dominate prediction uncertainty. The proposed method relies on minimal data at population-level, which is always likely to be available. This, combined with its numerical efficiency, makes the proposed method attractive to be used either as a standalone inference and prediction scheme or in conjunction with other inference and/or predictive models.

Network inference from population-level observation of epidemics.

Using the continuous-time susceptible-infected-susceptible (SIS) model on networks, we investigate the problem of inferring the class of the underlying network when epidemic data is only available at population-level (i.e., the number of infected individuals at a finite set of discrete times of a single realisation of the epidemic), the only information likely to be available in real world settings. To tackle this, epidemics on networks are approximated by a Birth-and-Death process which keeps track of the number of infected nodes at population level. The rates of this surrogate model encode both the structure of the underlying network and disease dynamics. We use extensive simulations over Regular, Erdos-Rényi and Barabási-Albert networks to build network class-specific priors for these rates. We then use Bayesian model selection to recover the most likely underlying network class, based only on a single realisation of the epidemic. We show that the proposed methodology yields good results on both synthetic and real-world networks.

Optimization of Salmonella Typhi biofilm assay on polypropylene microtiter plates using response surface methodology.

The objective of this study was to develop an optimized assay for Salmonella Typhi biofilm that mimics the environment of the gallbladder as an experimental model for chronic typhoid fever. Multi-factorial assays are difficult to optimize using traditional one-factor-at-a-time optimization methods. Response surface methodology (RSM) was used to optimize six key variables involved in S. Typhi biofilm formation on cholesterol-coated polypropylene 96-well microtiter plates. The results showed that bile (1.22%), glucose (2%), cholesterol (0.05%) and potassium chloride (0.25%) were critical factors affecting the amount of biofilm produced, but agitation (275 rpm) and sodium chloride (0.5%) had antagonistic effects on each other. Under these optimum conditions the maximum OD reading for biofilm formation was 3.4 (λ600 nm), and the coefficients of variation for intra-plate and inter-plate assays were 3% (n = 20) and 5% (n = 8), respectively. These results showed that RSM is an effective approach for biofilm assay optimization.

A nationwide survey of prevalence of pediculosis in children and adolescents in iran.

BACKGROUND: Since 2005, pediculosis is one of the obligatory reportable diseases from community to the Center of Disease Control. This study is the first nationwide survey on the prevalence of pediculosis and some associated risk factors in Iranian children and adolescents. METHODS: National data of the Ministry of Health and Medical Education were gathered in 2005 through school screening programs and obligatory reports from the country health centers. RESULTS: 12,359,448 Iranian children and adolescents were screened in 2005. Overall, 213,450 students, consisting of 198,947 girls and 14,320 boys were reported to have pediculosis. The prevalence of pediculosis was 581 per 100,000 population that varied from 1/100 000 to 8,303/100,000. In general, the highest prevalence of pediculosis was documented in south-eastern cities. The prevalence of pediculosis was significantly higher in girls than in boys (93% vs.7%, respectively, p<0.0001). In both genders, the highest prevalence of pediculosis was documented in the 6-10- year age group. Of those infected, 62% lived in rural areas, and 32% of those infected with pediculosis had a previous history of this infection. Most (99.37%) infected individuals had head lice, the rest had body and pubic pediculosis. CONCLUSION: The prevalence of pediculosis is low in Iranian children and adolescents, but this infestation is still a health problem in some south-eastern cities with warm climate and low to middle socioeconomic status.

An adjustable, high sensitivity, wide dynamic range two channel wave-front sensor based on moiré deflectometry.

An adjustable, high sensitivity, wide dynamic range two channel wave-front sensor based on moiré deflectometry has been constructed for measuring distortions of light wave-front transmitted through the atmosphere. In this approach, a slightly divergent laser beam is passed through the turbulent ground level atmosphere and then a beam-splitter divides it into two beams. The beams pass through a pair of moiré deflectometers which are installed parallel and close together. From deviations in the moiré fringes we calculate the two orthogonal components of angle of arrival at each location across the wave-front. The deviations have been deduced in successive frames which allows evolution of the wave-front shape to be determined. The dynamic range and sensitivity of detection are adjustable by merely changing the separation of the gratings and the angle between the rulings of the gratings in both of channels. The spatial resolution of the method is also adjustable by means of bright, dark, and virtual traces for given moiré fringes without paying a toll in the measurement precision.

Nationwide report on the findings of integrated school health screening program in iran.

BACKGROUND: Screening of students' health problems could lead to timely prevention and control of many health disorders. This study aimed to determine the nationwide prevalence of common disorders through school health screening program in Iran METHODS: This cross-sectional national screening program was conducted in 2007-2008 among first- and third-grade-students in primary schools, first-grade-students of middle and high schools of all provinces in Iran. RESULTS: Data were obtained from 3,124,021 (81.9%) students reported from the whole country classified into 33 geographical zones. Of total students studied, 12.48% had weight abnormalities, 4.77% had visual disorders, 3.95 % had head lice, 2.24% had behavioral disorders, and 0.6% had hearing disorders. Among students studied, 0.4%, 0.7%, 0.4% and0.8% had endocrine, psychological, neurological and genitourinary disorders, respectively. In addition, 2.1%, 1.9%, 1.8%, 0.8%0.5%, 0.3% and 0.3% of students had ear, nose & pharynx disorder, anemia, skin & hair, cardiac, abdominal, vertebral and lung problems, respectively. In elementary schools, 57.6% of first-grade-students with at least one disorder were managed in outpatient settings and 6% of them were hospitalized for more investigation. Among third-grade-students of elementary schools, these values corresponded to 13.2% and 1.1%, respectively. Among first grade students of middle and high schools, this prevalence was 58.5% and 44.6% and 1.2% and 0.3% of students were hospitalized for more investigation. CONCLUSION: This integrated school screening program revealed a considerably high prevalence of health disorders among school students. These results might help health policy makers to design future health promoting programs.

Woman abuse and pregnancy outcome among women in Khoram Abad, Islamic Republic of Iran.

We carried out a descriptive analysis on the pregnancy outcome in 313 pregnant women abused, 160 non-abused). Abuse was statistically significantly correlated with mean weight gain during pregnancy, mean frequency of the prenatal care, prolonged labour (dystocia), premature rupture of membrane, low mean birth weight and mean gestational age at birth. Given the high likelihood that a woman will access health care services during her pregnancy, physicians providing prenatal care are in a strategic position to screen for partner abuse.

Woman abuse and pregnancy outcome among women in Khoram Abad, Islamic Republic of Iran

We carried out a descriptive analysis on the pregnancy outcome in 313 pregnant women [153 abused, 160 non-abused]. Abuse was statistically significantly correlated with mean weight gain during pregnancy, mean frequency of the prenatal care, prolonged labour [dystocia], premature rupture of membrane, low mean birth weight and mean gestational age at birth. Given the high likelihood that a woman will access health care services during her pregnancy, physicians providing prenatal care are in a strategic position to screen for partner abuse

Results in 158 consecutive cadaveric renal transplantations.

OBJECTIVES: We investigated the outcome of deceased donor kidney transplantations performed in a single center in a developing country. MATERIALS AND METHODS: A total of 158 patients (69 male and 89 female patients, including 32 children) received kidney grafts obtained from deceased donors between March 1996 and October 2004. Cadaveric renal grafts were transplanted after a cold ischemia time of 4 to 24 hours (mean, 12.5 hours). Retransplantation was performed in 19 recipients. Induction immunosuppression was achieved with antithymocyte globulin. The diagnosis of acute graft rejection was based on histopathological findings. RESULTS: Primary graft function was observed in 77% of cases. Posttransplantation complications were: surgical (n = 60; 38%), systemic bacterial and viral infections (n = 33; 21%), acute rejection (n = 47; 30%), and malignancy (n = 2; 1.3%). Seventeen recipients died with a functioning graft, and 23 more grafts were lost. The 7-year actuarial survival rates were 89% and 75% for recipients and grafts, respectively. CONCLUSIONS: The kidney transplantation program in Kuwait is steadily growing. Kidney grafts obtained from deceased donors contributed 28% of the transplantation activity and were associated with a high rate of primary function. Overall actuarial recipient and graft survival rates were comparable to those reported by larger centers.

The effects of anaesthesia on cortical stimulation in rats: a functional MRI study.

The purpose of this study was to investigate the affects of equithesin and isoflurane on cortical activation in the rat using fMRI. Eight healthy male Sprauge-Dawley rats were anaesthetised separately with isoflurane and equithesin following a week in between. Functional EPI images were acquired in axial and sagittal orientations on a Bruker 47/30 Biospec system. Each experiment included repetitive air puffs over the right face region and was divided into 4 OFF (no stimulation) and 3 ON (repeated air puffs) periods. Changes in the BOLD-fMRI signal response were analysed using a box-car response function (SPM99) correlated against each voxel to determine regions of activation (p Corrected <0.0001, Z score>3.54). Neural activation was not detected when equithesin was used except in one rat compared to consistent activation with isoflurane in all 16 functional EPI scans. Equithesin appears to have effectively reduced brain activity in response to sensory stimuli. Isoflurane anaesthesia (1.6%) showed consistent, robust neural activations. It is therefore recommended that equithesin should be further investigated with other functional modalities or behavioural tests prior to consider it as an anaesthetic agent for future functional MRI studies.

Relationship between the area of cartilage shown on the magnetic resonance imaging middle-slice image of the medial and lateral tibial cartilages with cartilage volume and grade of osteoarthritis over time.

OBJECTIVE: Knee cartilage volume measurement requires significant time and training. Simplifying the measurement may improve feasibility. We investigated whether the area of cartilage shown on the middle slice of the medial and lateral tibial cartilages on sagittal MRI correlates with radiological features of osteoarthritis (OA), cartilage volume, and longitudinal change in cartilage volume. METHODS: One hundred and seventy-three subjects (normal and osteoarthritic), who had serial magnetic resonance imaging (cartilage volume measured) and baseline weight-bearing antero-posterior radiographs of the same knee were examined. RESULTS: In the lateral compartment, with increasing grade of OA there was a significant reduction in cartilage area. In the medial compartment, this was true for medial joint-space narrowing (after adjusting for gender). There was a moderate to strong association between cartilage area and volume, especially in those with early or no OA. However, when change over time was examined, the strength of these relationships was weak. CONCLUSION: Our data suggests that cartilage area may provide a simple surrogate measure of cartilage volume, in cross-sectional studies, after adjustment for gender: especially in subjects with early disease. However, before it can be widely used, further investigation will be required.

Effect of two different doses of metronidazole and tetracycline in bismuth triple therapy on eradication of Helicobacter pylori and its resistant strains.

BACKGROUND: Classic triple therapy with bismuth, tetracycline and metronidazole is one of the most economic and effective regimens for the eradication of Helicobacter pylori. The aim of the study was to assess the efficacy of two different doses of tetracycline (TET) and metronidazole (MET) on cure of H. pylori infection and its MET-resistant strains. MATERIAL AND METHODS: A total of 131 patients with duodenal ulcer were randomized into three groups and received the following medication for 2 weeks: group A, colloidal bismuth subcitrate (CBS) 3 x 120 mg + TET 3 x 500 mg + MET 3 x 250 mg/day; group B, CBS 3 x 120 mg + TET 3 x 500 mg + MET 3 x 125 mg/day; group C, CBS 3 x 120 mg + TET 3 x 250 mg + MET 3 x 125 mg/day. Control endoscopy was performed after 6 weeks. Two biopsy specimens from antral and three from corpus mucosa were taken for a urease test, histology and culture. Eradication was concluded if all three tests were negative for H. pylori. MET resistance was determined by the disc diffusion method. RESULTS: In total, 121 patients completed the study. Only two of the 43 patients in group A discontinued the therapy due to intolerance. Cure of H. pylori infection was achieved by per protocol analysis in 33 of 43 patients in group A (76.7%), in 20 of 40 patients in group B (50%) and in 20 of 38 patients in group C (52.6%) (P < 0.05 for A versus B or C). Forty-two out of 112 patients had H. pylori strains resistant to MET (42%). In each group, the cure rate of infection was higher in patients with MET-sensitive H. pylori than in MET-resistant H. pylori (80.7% versus 64.2% in group A, 60% versus 38.8% in group B and 52.6% versus 40% in group C, respectively). Increase of MET dose from 375 mg (in groups B and C) to 750 mg/day (in group A) seems to augment the eradication of MET-sensitive as well as MET-resistant strains (up from 52% to 84% and from 39% to 64%, respectively; P < 0.05). CONCLUSION: Cure rate of H. pylori infection under classic triple therapy remains unaffected by dose reduction of tetracycline but not of metronidazole. In countries with a high prevalence of metronidazole resistance, such as Iran, higher doses of metronidazole are probably needed to increase the cure rate of bismuth triple therapy.