Comparing machine learning to a rule-based approach for predicting suicidal behavior among adolescents: Results from a longitudinal population-based survey.

INTRODUCTION: Suicidal thoughts and suicide attempts are one of the most prominent public health concerns in adolescents and therefore early detection is important to initiate preventive interventions and closer monitoring. METHOD: We examined whether the Machine Learning models Random Forest and Lasso Regression better predict future suicidal behavior than a simple decision rule that classifies every adolescent with history of suicide ideation at baseline as at risk (current practice). We used data from a general population of students in second and fourth year of secondary education in Amsterdam, the Netherlands. RESULTS: Both the Random Forest and the Lasso Regression resulted in slightly better prediction. The AUC of the Random Forest (0.79) and Lasso regression (0.76) were both higher than the AUC of the decision rule (0.64). The Random Forest achieved slightly (but non-significantly) higher sensitivity than the decision rule (0.37 versus 0.34), with the same specificity (0.94). With Lasso Regression the sensitivity increased significantly (0.52), but at the expense of the specificity (0.85). LIMITATIONS: The loss of cases after merging the data, the use of self-reported data, confidential data collection and the use of only four questions to measure suicidal behavior. CONCLUSIONS: This is the first study applying Machine Learning techniques to predict future suicidal behavior on survey data collected in a general population of adolescents. Our study showed that integrating machine learning techniques in screening practice will result in a small improvement in the ability to predict suicide. The models need to be further optimized to improve accuracy.

Relationship between magnesium and lipids in patients with diabetes mellitus

Introduction: Non-communicable diseases, especially cardiovascular diseases (CVD), have become more prevalent across the world, more so in developing countries. Novel methods in the management of CVD risks in patients with diabetes mellitus, type 2 (DM2) requires constant attention and an ever-evolving approach. The role of magnesium supplementation in the management of CVD has been described, but the relationship between serum magnesium (Mg) and the lipid subsets have had conflicting results in different population groups. Methods: A cross-sectional study was performed by collecting data on patients with DM2 from a specialised diabetes clinic at Edendale Hospital, Pietermaritzburg, KwaZulu-Natal, South Africa, between July 1, 2015 and June 30, 2016. Lipid subsets (total cholesterol [TC], high-density lipoprotein cholesterol [HDL], low-density lipoprotein cholesterol [LDL] and triglycerides [TG]), age, sex and Mg were recorded for analysis. Results: A total of 495 clinical data sheets were analysed. The majority of participants were female (73.45%) with a mean age of 56.97 years. A statistically significant, positive, linear relationship was found between Mg and TC (R= 0.11;p= 0.01) as well as Mg and LDL R= 0.14;p= 0.001), but not between Mg and HDL (R= 0.02;p= 0.66) and Mg and TG (R= 0.01;p= 0.82). Discussion: The results of this study are similar to findings by a group of researchers in China and differ when compared with studies observing Caucasian patients. It is plausible that intrinsic ethnic differences in lipid metabolism and the various ways in which magnesium requiring enzymatic processes are utilised may be responsible for the results found in the present study population versus those found in Caucasian study participants in other countries. More research is required to determine the effect of magnesium supplementation and CVD outcomes in the present study population

Prevalence of Antiretroviral Drug Resistance in Patients Who Are Not Responding to Protease Inhibitor-Based Treatment: Results From the First National Survey in South Africa.

Limited data exist on human immunodeficiency virus type 1 (HIV-1) resistance in patients who are not responding to protease inhibitor (PI)-based regimens in resource-limited settings. This study assessed resistance profiles in adults across South Africa who were not responding to PI-based regimens. pol sequencing was undertaken and submitted to the Stanford HIV Drug Resistance Database. At least 1 major PI mutation was detected in 16.4% of 350 participants. A total of 53.4% showed intermediate resistance to darunavir/ritonavir, whereas high-level resistance was not observed. Only 5.2% and 32.8% of participants showed high-level and intermediate resistance to etravirine, respectively. Although the prevalence of major PI mutations was within previously reported ranges, most patients will likely experience virological suppression during receipt of currently available South African third-line regimens.

Seven-year time trends in energy balance-related behaviours according to educational level and ethnic background among 14-year-old adolescents.

OBJECTIVE: To assess seven-year time trends in energy balance-related behaviours in 14-year-old adolescents living in an urban area and to examine the influence of educational level and ethnicity on these time trends. DESIGN: Second grade students (mean age 13·6 years) filled in questionnaires about the energy balance-related behaviours of breakfast consumption, fruit and vegetable consumption, physical activity and screen-time behaviour from school years 2006-2007 to 2012-2013. Energy balance-related behaviours were dichotomized and logistic regression analyses were used to examine time trends in healthy energy balance-related behaviours, including interaction terms for educational level and ethnicity. SETTING: Secondary schools in Amsterdam, the Netherlands. SUBJECTS: Per school year, 2185-3331 children participated. The total sample included 19 244 students of Dutch, Surinamese, Turkish and Moroccan ethnic background. RESULTS: A significant linear increase was found for positive screen-time behaviour (<2 h/d; OR per year=1·04; 95 % CI 1·03, 1·06). For daily vegetable consumption a non-linear negative trend was observed (school year 2012-2013 v. 2006-2007: OR=0·90; 95 % CI 0·80, 1·00). Time trends in screen time were significantly different across educational levels (P-interaction=0·002) and ethnic backgrounds (P<0·001), as were time trends in daily fruit consumption (P=0·017 and P=0·018, respectively) and, for ethnicity, trends in daily vegetable consumption (P<0·001). CONCLUSIONS: The increase in positive screen-time behaviour is a positive finding. However, discouraging screen time and promoting other healthy behaviours, more specifically daily fruit and vegetable consumption, remain important particularly among adolescents enrolled in pre-vocational education and of non-Dutch ethnic background.

Neighborhood socioeconomic deprivation characteristics in child (0-18 years) health studies: a review.

BACKGROUND: Growing up in socioeconomically deprived neighborhoods has been shown to have negative health effects on children. However, the most recent review on which measures are used to investigate the association between neighborhood characteristics and child (0-18 year) health included studies only until 2004. Insight into more recent research is needed for the further development of these measures. OBJECTIVES: To review neighborhood socioeconomic deprivation characteristics used in recent studies investigating the relationship between neighborhood socioeconomic deprivation and child health. METHODS: Sensitive search in MEDLINE, Embase, PsycINFO, Sociological Abstracts databases (2004-2013). RESULTS: Ultimately, 19 studies were included. We found ten neighborhood socioeconomic deprivation constructs, of which income/wealth, employment, and education were most frequently used. The choice for neighborhood characteristics seemed independent of the health outcome and in most cases was not based on a specific theoretical background or earlier work. CONCLUSION: Studies vary regarding study designs, measures and outcomes. Researchers should clearly specify their choice of neighborhood socioeconomic deprivation characteristics; preferably, these should be theory-based and used consistently.

Public perceptions of the causes and prevention of obesity among primary school children.

OBJECTIVE: To investigate lay perceptions of the causes and prevention of obesity among primary school children. DESIGN: A cross-sectional survey of randomly selected sample of adults in a shopping centre. SUBJECTS: 315 adults in Melbourne, Australia. MEASUREMENTS: Subjects completed a self-completion questionnaire, in which they rated the importance of 25 possible causes of obesity and the importance of 13 preventive measures on four-point scales: not important; quite important; very important; extremely important. Demographic information about the respondents' age, sex, marital status, education level and parental status was also collected. RESULTS: The most important reported causes of childhood obesity were related to overconsumption of unhealthy food, parental responsibility, modern technology and the mass media. The most popular prevention activities were associated with specific actions aimed at children. Principal components analysis of the causes data revealed eight factors, provisionally named: parental responsibility, modern technology and media, overconsumption of unhealthy food, children's lack of knowledge and motivation, physical activity environment, lack of healthy food, lack of physical activity and genes. Two prevention factors were also derived, named government action and children's health promotion. Parents saw modern technology and media, and government activities as more important causes, and government policy as a more important means of prevention than nonparents and men. Women's responses tended to be similar to those of parents. There were few educational differences, although nontertiary educated respondents reported that modern technology and media were more important causes of obesity than did the tertiary educated. CONCLUSION: The findings suggest that the public appears to hold quite sophisticated views of the causes and prevention of children's obesity. They suggest that a number of prevention strategies would be widely supported by the public, especially by parents.

Antigenic analysis of SAT 2 serotype foot-and-mouth disease virus isolates from Zimbabwe using monoclonal antibodies.

This paper compares strains of foot-and-mouth disease (FMD) serotype SAT (South African Territories) 2 viruses isolated from Zimbabwe and other African countries using monoclonal antibodies (MAb). A sandwich-ELISA was used to examine the relative binding of anti-SAT 2 MAb to the various viruses. The MAb-binding profiles of viruses isolated from field samples were compared using hierarchical cluster analysis. Viruses were obtained from game animals, mainly African buffalo (Syncerus caffer) which is the natural host and reservoir for SAT serotypes in Africa, and from cattle showing clinical signs of FMD, as well as from animals suspected of carrying the virus subclinically. Some isolates have been adapted for use as vaccine strains. The results showed that most of the Zimbabwe isolates collected between 1989 and 1992 were an antigenically closely-related group. Although differences were observed between Zimbabwe isolates collected between 1989 and 1992 and those collected in 1987, there was no correlation with the different MAb binding patterns within the 1987 group and the epidemiological information received from the field. Similar profiles were observed for many SAT 2 viruses, including viruses isolated over a 50-year period and from geographically distant areas. This indicates an inherent stability in antigenic profiles of SAT 2 viruses. The MAb panel was capable of assessing antigenic variation, since very different profiles were obtained for some isolates. The work also allowed comparison and characterization of anti-type SAT 2 MAb from different laboratories. The findings are discussed with reference to selection of vaccine strains.

Rhipicephalus zambeziensis unlikely to transmit foot-and-mouth disease virus.

The potential of the ixodid tick, Rhipicephalus zambeziensis, was investigated as a vector in the transstadial transmission of the foot-and-mouth disease virus by feeding nymphae on viraemic (log 1.0-4.0 TCID50/ml) cattle. Suspensions were prepared, at various intervals after detachment, from pools of engorged nymphae--some of which were allowed to moult first. Suspensions were inoculated into sucking mice, cell cultures and, in some cases, cattle to detect the FMD virus. Newly moulted adult ticks, derived from nymphae which had fed on viraemic cattle, were also allowed to feed on susceptible cattle. The pattern of virus detection indicated that the FMD virus was capable of surviving at least 3 d in engorged nymphae, but less than 7 d following repletion. It was concluded that R. zambeziensis is unlikely to transmit the FMD virus.

Hyperdynamic sepsis in baboons: II. Relation of organ damage to severity of sepsis evaluated by a newly developed morphological scoring system.

The purpose of our study was to set up a baboon hyperdynamic sepsis model with live bacteria administration, which produces within 8 hr an organ failure comparable to human pathological conditions. Twelve adult male baboons were instrumented and studied for 8 hr under pentobarbital (2-3 mg/kg BW/hr) anesthesia breathing spontaneously. The animals were divided into two groups: 1) Live Escherichia coli were infused intravenously at a dose of 1.0-2.0 x 10(10) CFU/kg BW over 8 hr; 2) Live E. coli were infused i.v. at a dose of 5 x 10(8) CFU/kg BW over 2 hr. Organ damage was monitored by a newly developed scoring system. Organ damage was clearly dependent on the concentration of the bacterial challenge. Bacterial challenge at a dosage of 5.0 x 10(8) produces insignificant hemodynamic effects, while the 1.0-2.0 x 10(10) animals demonstrated massive hemodynamic alterations and needed much higher fluid support. The higher E. coli dosage was associated with an overwhelming organ damage seen, e.g., from the lung weight (12 g/kg BW vs. 9.6 g/kg BW with the lower dosage) or from the organ failure score, which is based on macroscopic pathology, histological data and organ weight. The percentage of animals with one, two, or three organ failures (organ failure score > or = 2) was higher in baboons with the higher dosage/kg BW. Therefore, we believe that the less severe organ damage in the acute phase after 8 hr with live bacteria 5 x 10(8) CFU/kg BW infusion over 2 hr is better to monitor the efficacy of newly developed therapeutic regimens, since in another set of experiments this model still produces lethal organ damage (80%) in a subchronic setting over 72 hr.

A review of the literature on the prevalence of Class III malocclusion and the mandibular prognathic growth hypotheses.

From this review of the literature it appears that we may draw the following conclusions. The incidence of Class III malocclusions is at most 4.2% (Goose et al. 1957, Ast et al. 1965; Knowles 1966, Thylander and Myrberg 1973). The development of various condyle growth hypotheses have lead us to believe that the condyle behaves in a rather unique manner. The condyle does not appear to be an epiphysis, neither does it behave the same as the cranium. It is a unique cartilaginous structure that cannot grow against intermittent or continuous forces (Copray 1985). The cybernetic model as proposed by Petrovic and co workers (1977) that eloquently describes the condyle to be stimulated by a cybernetic switch that connects to the periodontal ligament also does not seem to have much validity. It appears that the lateral pterygoid muscle and the temporo-mandibular condylar frenum have been ascribed capabilities that do not comply to the results of condylotomy studies. Gorette-Nicaise, Awn, and Dhem (1983) as well as the study by Whetten, and Johnston (1985) have shown that neither the absence of the lateral pterygoid muscle nor the physical volumetric expansion of the airway increases condylar growth. It appears that increase in the pressure applied to the condyle could decrease condyle cell proliferation (Armstrong 1961; Thilander 1963; 1965: Janzen and Bluher 1965; Graber 1969; Petrovic 1972; Graber and Muller 1974; Graber 1975;) with resulting growth attenuation. Accordingly, condylar growth is controlled by physical restraint, the absence which leads to incremental growht. The presence of mechanical pressure of adequate duration and magnitude, thus, should limit growth of the young actively growing condyle.

Evaluation of clinical isolates of Pseudomonas aeruginosa for ribosomal resistance to tobramycin.

The suggested use of tobramycin in selective decontamination of the digestive tract led to the investigation of the part played clinically by ribosomal resistance in Pseudomonas aeruginosa. Examination of 32 tobramycin-resistant isolates, both enzyme and non-enzyme producing, suggests that ribosomal resistance is clinically important.

The genetic relationship between the Döhne- and the Walrich-merino.

The Döhne- and the Walrich Sheep breeders' societies amalgamated in 1982 to form an enlarged Döhne Merino Breed Society. Both breeds are dual-purpose, polled breeds with high fertility as well as good wool and mutton characteristics. Apparently they have a similar genetic background, both being developed out of local Merino ewes and dual-purpose Merino-type sheep from Europe. Studies of biochemical polymorphisms in the blood of 224 Döhne and 204 Walrich Merino established a close relationship between these two breeds.

Phase mapping from left ventricular radionuclide ventriculograms: interobserver reliability and accuracy of the programme.

Phase analysis of data from radionuclide ventriculograms is known to provide space-time information on the mechanical emptying of pixels located in the ventricular regions. It could therefore perhaps be useful for detecting abnormal sequences of contraction of the ventricles as well as to localize sites of premature electromechanical action. The phase programme used in this investigation is designed to trace the electromechanical action of the ventricles from colour-coded phase images (first harmonic Fourier transform), not only visually from a cinematic representation, but particularly from a data output of x, y coordinates and phase angles of sites chosen as they empty in the ventricular regions. Six healthy baboons were subjected to conventional radionuclide ventriculography, performed hourly for the duration of 11 h under anaesthesia. The programme was used by two independent observers to map the progression of emptying for each of the thus acquired 66 left ventricular phase images. The interobserver reliability and the accuracy achieved in mapping normal contraction patterns was found to be good. Abnormalities which appeared during the prolonged anaesthesia and which were confirmed with 12 lead electrocardiography were likewise detected consistently.

The sensitivity of radionuclide and thermodilution techniques to detect cardiac dysfunction in the baboon model during prolonged anaesthesia.

This study was undertaken to evaluate the fluctuations of cardiac parameters in a baboon model during pentobarbitone anaesthesia which will serve as a baseline control for shock studies. Thermodilution and radionuclide methods were used to determine cardiac parameters. Radionuclide studies were repeated without any cardiac catheters to assess the effect of these on cardiac performance. The results represent baseline fluctuations in cardiac parameters against which cardiac dysfunction can be diagnosed in shock studies. The results also indicate that cardiac catheterisation does not affect cardiac performance significantly.

Comparative radionuclide and thermodilution determinations of cardiac output and stroke volume in the baboon (Papio ursinus).

Thermodilution cardiac output determinations and multigated equilibrium blood-pool scintigraphy were performed in ten healthy chacma baboons (Papio ursinus). The correlation was moderately good between both the radionuclide and thermodilution stroke volume (r = 0.58, SEE = 3 ml; SVth = 0.78SVr + 15.6 ml) as well as the cardiac output (r = 0.72, SEE = 0.2 liter/min; COth = 0.56 Cor + 2.1 liter/min). The attenuation depth dr as determined by radionuclide techniques was found to correlate well with the radiologically determined values dx (r = 0.8, SEE = 0.4 cm; dx = 0.87dr + 0.72 cm) which validated the depth values used in the calculations.

A modified neutral sucrose centrifugation method for rapid detection of DNA damaged by gamma-radiation and repair in human lymphocytes.

1. The influence of 60Co gamma-radiation on the sedimentation behaviour of human lymphocyte nucleoids in neutral sucrose gradients was studied with the aid of a modified fluorescent monitor system consisting of the DNA-binding dye, Hoechst 33258 and a vertical centrifuge rotor. 2. A combined method employing the sedimentation procedure and the incorporation of tritiated nucleosides was utilized to evaluate the repair of gamma-radiated DNA.

The pathogenesis of Yersinia enterocolitica gastroenteritis.

Of nine Y. enterocolitica serotypes examined by us, only type 3 was shown to be enteropathogenic. 3 of 16 strains recovered from clinical material, produced a heat-stable toxin similar to that reported in E. coli. A fourth isolate produced histological changes resembling those associated with salmonellae. The mechanism whereby the majority of Y. enterocolitica strains produce diarrhoea is uncertain. Our isolates may have lost a plasmid essential for enteropathogenicity, or they may resemble the 'classical' enteropathogenic strains of E. coli for which no satisfactory experimental model exists. Further studies on freshly isolated strains are in progress in order to determine the prevalence of enterotoxigenic Y. enterocolitica.