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PubMed1996

The effect of the media on suicide: evidence from Japan, 1955-1985.

Research on media impacts on suicide has been largely restricted to the United States, a Christian nation marked by moral aversion to suicide. The present study extends the analysis to an Eastern nation, Japan, where people are less critical of those who suicide. Such a cultural definition of suicide might multiply imitative effects. Yule-Walker times series estimates indicate that the imitative effect is restricted to stories concerning Japanese victims. Further, the increase is similar in magnitude to that reported in the American cultural context. The Japanese audience may not be as predisposed to media effects, given a lower divorce rate, low couple centeredness, and a high level of extended family social support. These factors may offset a potentially very high "Werther effect." The model explains 88% of the variance in monthly Japanese suicide rates.

Cross-Cultural Comparison↗
PubMed1996

[Explanatory factors of length of stay at the diagnosis-related group 129: common pneumonia and pleurisy, aged over 69 and/or associated co-morbidities].

BACKGROUND: Utilization of diagnosis related groups (DRGs) for hospital comparison, based on length of stay (LOS). OBJECTIVES: Inside a DRG (Pneumonia and pleurisy > 69 and/or associated comorbidities), to point out the explicative factors of LOS and the variables which could be recorded for a better description of these patients. SETTING: Pneumologic unit of Limoges' teaching hospital. METHODS: From 01-01-94 to 31-12-94, the DRG 129 was studied through the medical unit summary, the performance status at entrance, the social complexity, the characteristics of pneumonia (symptoms, temperature, arterial pressure...), the severity by American Thoracic Society (ATS) criteria, the procedures (chest X-ray, biology, fibroscopy...), the antibiotic treatments (intravenous and oral). Statistical tests associated univariate analysis, linear and logistic regressions. RESULTS: LOS was 15.53 d +/- 8.57 (m +/- SD). The mathematical model explains 69% of the variance of LOS logarithm. The logistic regression found 5 variables with a significant odds-ratio (OR) for an increased LOS: a high ATS score, repeated laboratory tests, a complex social situation, an increase length of antibiotic treatment (intravenous and oral). CONCLUSION: A better description of LOS, inside a DRG, needs supplementary variables. For pneumonia admitted in Limoges' hospital, the severity of the disease, the number of laboratory tests, the antibiotic treatment, the social complexity are the more significant indicators.

Age Factors↗
PubMed1997

Lack of lymphangiogenesis in human primary cutaneous melanoma. Consequences for the mechanism of lymphatic dissemination.

Cutaneous melanoma has an initial preference for lymphatic spread. Remarkably, melanoma progression toward this metastasizing phenotype is accompanied by intense blood vessel angiogenesis (hemangiogenesis), but lymphangiogenesis, the formation of new lymph vessels in the tumor, has never been reported. To investigate how primary melanoma cells interact with the existing lymphatic microvasculature, and whether lymphangiogenesis occurs, an immunostaining was developed that differentially decorates blood and lymph vessels in frozen tissue sections. The density and distribution of both these vessel types in and around thin (< or = 1.5 mm) and thick (> or = 1.5 mm) primary melanoma lesions and in normal and uninvolved skin were determined. Although especially in thick melanoma lesions a significant increase in blood vessel density was observed, lymphatic density remained unaltered, showing that lymphangiogenesis did not occur. Morphological analysis indicated, however, that melanoma progression is accompanied by a sequence of events that involves hemangiogenesis supporting tumor expansion, especially in the vertical growth phase. Often, stromal sepia are formed around the blood capillaries in the tumor neovasculature protecting them from invasion. Lymph vessels inside the tumor were infrequently observed. However, subepidermal lymph vessels often seemed to be entrapped and penetrated by the expanding tumor mass. In this way, hemangiogenesis, as the driving force behind tumor expansion, might indirectly increase the chance of lymphatic invasion in the absence of lymphangiogenesis. This model explains the paradox that, although melanoma metastasis seems to require angiogenesis, a consistent relation of prognosis with blood capillary density in primary cutaneous melanoma is lacking.

Biomarkers↗
PubMedDate not supplied

The basis for clinicians' caries risk grouping in children.

Despite the growing emphasis on targeting care to high-risk groups, little is known about the factors used by clinicians to designate risk. This study investigates the degree to which factors measured in a typical dental health survey are used by clinicians in assigning children to dental disease risk groups. A random sample of 9690 children aged 5-15 years was selected from the South Australian School Dental Service. Dentists or dental therapists judged each child as low-, medium-, or high-risk for dental disease. Clinicians recorded caries experience (DMFS/dmfs), and children's parents completed a questionnaire on dental behaviors and socioeconomic status (SES). Two binary logistic models were fitted using the risk grouping as the outcome variable, one comparing low- with moderate-risk and the other comparing moderate- with high-risk. Sixty percent of children were judged as moderate-risk, 27% as low-risk, and only 13% as high-risk. In the logistic models, proximal DMFS/dmfs were stronger predictors of assignment to the higher-risk groups than were factors indicating past occlusal caries, while factors describing caries on buccal or lingual surfaces appeared unimportant. Untreated lesions on permanent and primary teeth were among the strongest predictors of assignment to the higher-risk groups. Other significant factors (P < 0.05) were: exposure to professionally applied fluoride and sealants, country of birth, frequency of toothbrushing, and exposure to fluoridated water. No SES factors reached significance. The models explained nearly one-half the variation in the risk predictions. Clinical markers of past caries experience explained the greatest variation in the judgments, showing that clinicians base their risk predictions largely on children's past disease. The three types of surfaces contribute unevenly to the judgments and unrestored caries was the largest contributor to the decision.

Adolescent↗
PubMedDate not supplied

Factors associated with primary care residents' satisfaction with their training.

BACKGROUND AND OBJECTIVES: Satisfaction is known to impact work performance, learning, recruitment, and retention. This study identifies the factors associated with primary care residents' satisfaction with their training. METHODS: We used a cross-sectional survey based on the Price-Mueller model of job satisfaction. The model included 14 job characteristics, four personal characteristics, and four demographic factors. Data were collected in February and March 1996 from residents in three primary care training programs (family practice, pediatrics, and internal medicine) at a large academic medical center. The same standardized, self-administered questionnaires were used in all three departments. RESULTS: Seventy-five percent (n = 119) of the residents returned questionnaires. Five job characteristics were positively associated with resident satisfaction: continuity of care, autonomy, collegiality, work that encourages professional growth, and work group loyalty. Role conflict, a sixth job characteristic, was negatively associated with satisfaction. The personal characteristic of having an optimistic outlook on life was also positively associated with satisfaction. The model explained 66% of the variation in self-reported satisfaction. CONCLUSIONS: The satisfaction of the residents was significantly associated with six job characteristics and one personal factor. Interventions based on these job characteristics may increase resident satisfaction and may lead to better patient outcomes, better work performance, greater patient satisfaction, and more success in recruiting top students into a residency.

Education↗
PubMedDate not supplied

[Drug use and dependence in schizophrenia].

Drug dependence is common in schizophrenia. Two main models explain this association: drugs precipitate psychosis in a vulnerable subject, and drugs use to self-medicate positive and negative symptoms and neuroleptics side effects. We investigated the prevalence of psychoactive substance use and dependence in schizophrenia and its association with the subtype of schizophrenia. The sample consisted of 56 outpatients with schizophrenia according to ICD-10, between 18 and 40 years, and a control group with 56 subjects with other different disorder. They were evaluated with Addiction Severity Index (ASI) and Positive And Negative Syndrome Scale (PANSS), sociodemographical, clinical and toxicological characteristics were evaluated too. Patients were classified in subtype negative, positive or mixed according to scoring in PANSS. Schizophrenics were reevaluates at six months of development. There were higher cocaine, alcohol, cannabis and nicotine use in schizophrenics. The patients with negative subtype of schizophrenia had more clinical severity, less scoring in alcohol and drugs subscales of ASI, lower prevalence of nicotine dependence and cocaine, amphetamines, cannabis and opioids use. Drugs use were associated with a poor compliance of treatment. Therefore, cannabis and cocaine dependence, regular alcohol use and tobacco use are more prevalent in schizophrenic than control group with other mental disorders. Negative subtype had lower drug use.

Adolescent↗
PubMed1998

Recognition and management of horizontal canal benign positional vertigo.

OBJECTIVE: We reviewed the features of nystagmus in 24 patients with horizontal canal benign positional vertigo (BPV). Patients were treated with canalith repositioning maneuvers. Our goal was to develop a framework for distinguishing horizontal from posterior canal BPV and to further develop a mechanistic model explaining the horizontal canal variant of BPV. STUDY DESIGN: The study design was a retrospective case review with prospective treatment outcome and follow-up. SETTING: The study was performed at a secondary and tertiary referral center for vertigo and dizziness. PATIENTS: The diagnosis of horizontal canal BPV was based on: 1) recurrent brief episodes of positional vertigo; 2) paroxysmal bursts of horizontal positional nystagmus; and 3) lack of any other identifiable central nervous system disorder to explain the nystagmus. Patient average age was 62 years, and average duration of symptoms was 12 weeks. INTERVENTIONS: We documented patients' symptoms and the characteristics of nystagmus. We reviewed the effectiveness of several similar canalith repositioning treatments. MAIN OUTCOME MEASURE: We observed and recorded factors that distinguish horizontal from posterior canal BPV. We monitored the direction of nystagmus, the type of maneuver that evoked the nystagmus, and the response to canalith repositioning. RESULTS: Symptom description alone was not sufficient to distinguish among canal types of BPV. Horizontal geotropic direction-changing positional nystagmus was observed in 19 of 24 patients. The other patients had ageotropic nystagmus. Both types were distinct from the nystagmus of posterior canal BPV. Response to canalith repositioning was 75% at 1 week of follow-up. Conversion of BPV from one canal to another occurred in some patients, but each canal could be treated individually. CONCLUSIONS: Patients with positional vertigo should undergo Dix-Hallpike positioning and supine lateral head turns to each side. Paroxysmal positional horizontal nystagmus that changes direction with changes in head position strongly suggests the diagnosis. Canalith repositioning for posterior canal BPV may fail in horizontal BPV. A 360 degrees barbecue rotation toward the presumably healthy ear done two to four times or until nystagmus disappears may result in more rapid resolution of symptoms.

Adult↗
PubMed1998

An investigation of dental student practice preferences.

This study explored characteristics hypothesized to influence dental student long-range practice preferences. Dental students (N = 264) for this study were selected at random from all dental students in one state who rated practice arrangements they most prefer to be in five years after graduation. The rating instrument was composed of two items measured on 5-point Likert-type scales. The independent variables were student gender, year of dental study, and practice arrangement. The research design was a 2 x 4 x 3 completely randomized, fixed-factor, factorial analysis of variance (ANOVA). The ANOVA model explained 48 percent of the variance in student practice arrangement ratings. Both males and females rated solo ownership as the most favorable practice arrangement. Males rated the solo owner arrangement more favorably than did females, while females had a stronger preference for the employee practice arrangement than did males. Study results have implications for dental educators in their efforts to structure curricula to meet diverse student needs, to assess personnel needs and enhance the accuracy of projections, and to evaluate the effect of practice preferences on the health care system.

Administrative Personnel↗
PubMed1998

[Implantable automatic defibrillators in the treatment of ventricular tachycardia].

The implantable automatic defibrillator (IAD) is the treatment of choice of malignant ventricular arrhythmias or those resistant to pharmacological or ablative techniques. However, the small number of implantations in France, the presence of many different models, the cost and sophistication of the latest models explain why IAD remain a poorly known therapeutic method because it is highly specialised and reserved for cardiological departments with a rhythmological interest. Several factors suggest that the number of implantations will increase in the future. Firstly, the techniques of implantation have been considerably simplified and associated with technological improvements of the devices, and, secondly, publication of several trials (MADIT, AVID), even if the conclusions in favour of IAD must be carefully interpreted, will change our methods of management of patients with severe ventricular arrhythmias. The current indications of IAD in ventricular tachycardia and future prospects are discussed in the light of new data.

Defibrillators, Implantable↗
PubMed2005

Loop model: mechanism to explain partial gene duplications in segmented dsRNA viruses.

Gene rearrangements in a head-to-tail fashion have been described several times for gene segments of the rota-, phytoreo-, and orbiviruses. Several mechanisms have been proposed to explain the occurrence of partial duplications, however, none of these models has been fully satisfactory to explain the occurrence of all the observed duplicated genes. Based on recently available structural data about the lambda3 RNA-dependent-RNA-polymerase of reoviruses, we propose the 'loop model' as a plausible explanation for the occurrence of partial gene duplications in dsRNA viruses.

Computer Simulation↗
PubMed2025

APNet, an explainable sparse deep learning model to discover differentially active drivers of severe COVID-19.

MOTIVATION: Computational analyses of bulk and single-cell omics provide translational insights into complex diseases, such as COVID-19, by revealing molecules, cellular phenotypes, and signalling patterns that contribute to unfavourable clinical outcomes. Current in silico approaches dovetail differential abundance, biostatistics, and machine learning, but often overlook nonlinear proteomic dynamics, like post-translational modifications, and provide limited biological interpretability beyond feature ranking. RESULTS: We introduce APNet, a novel computational pipeline that combines differential activity analysis based on SJARACNe co-expression networks with PASNet, a biologically informed sparse deep learning model, to perform explainable predictions for COVID-19 severity. The APNet driver-pathway network ingests SJARACNe co-regulation and classification weights to aid result interpretation and hypothesis generation. APNet outperforms alternative models in patient classification across three COVID-19 proteomic datasets, identifying predictive drivers and pathways, including some confirmed in single-cell omics and highlighting under-explored biomarker circuitries in COVID-19. AVAILABILITY AND IMPLEMENTATION: APNet's R, Python scripts, and Cytoscape methodologies are available at https://github.com/BiodataAnalysisGroup/APNet.

COVID-19↗
PubMed2006

Modeling of oxygen transport and cellular energetics explains observations on in vivo cardiac energy metabolism.

Observations on the relationship between cardiac work rate and the levels of energy metabolites adenosine triphosphate (ATP), adenosine diphosphate (ADP), and phosphocreatine (CrP) have not been satisfactorily explained by theoretical models of cardiac energy metabolism. Specifically, the in vivo stability of ATP, ADP, and CrP levels in response to changes in work and respiratory rate has eluded explanation. Here a previously developed model of mitochondrial oxidative phosphorylation, which was developed based on data obtained from isolated cardiac mitochondria, is integrated with a spatially distributed model of oxygen transport in the myocardium to analyze data obtained from several laboratories over the past two decades. The model includes the components of the respiratory chain, the F0F1-ATPase, adenine nucleotide translocase, and the mitochondrial phosphate transporter at the mitochondrial level; adenylate kinase, creatine kinase, and ATP consumption in the cytoplasm; and oxygen transport between capillaries, interstitial fluid, and cardiomyocytes. The integrated model is able to reproduce experimental observations on ATP, ADP, CrP, and inorganic phosphate levels in canine hearts over a range of workload and during coronary hypoperfusion and predicts that cytoplasmic inorganic phosphate level is a key regulator of the rate of mitochondrial respiration at workloads for which the rate of cardiac oxygen consumption is less than or equal to approximately 12 mumol per minute per gram of tissue. At work rates corresponding to oxygen consumption higher than 12 mumol min(-1) g(-1), model predictions deviate from the experimental data, indicating that at high work rates, additional regulatory mechanisms that are not currently incorporated into the model may be important. Nevertheless, the integrated model explains metabolite levels observed at low to moderate workloads and the changes in metabolite levels and tissue oxygenation observed during graded hypoperfusion. These findings suggest that the observed stability of energy metabolites emerges as a property of a properly constructed model of cardiac substrate transport and mitochondrial metabolism. In addition, the validated model provides quantitative predictions of changes in phosphate metabolites during cardiac ischemia.

Adenosine Triphosphate↗
PubMed2005

How principles of domain formation in model membranes may explain ambiguities concerning lipid raft formation in cells.

Sphingolipid and cholesterol-rich liquid ordered lipid domains (lipid rafts) have been studied in both eukaryotic cells and model membranes. However, while the coexistence of ordered and disordered liquid phases can now be easily demonstrated in model membranes, the situation in cell membranes remains ambiguous. Unlike the usual situation in model membranes, under most conditions, cell membranes rich in sphingolipid and cholesterol may have a "granular" organization in which the size of ordered and/or disordered domains is extremely small and domains may be of borderline stability. This review attempts to explain the origin of the divergence between of our understanding of rafts in model membranes and in cells, and how the physical properties of model membranes can help explain many of the ambiguities concerning raft formation and properties in cells. How physical principles of ordered domain formation relate to limitations of detergent insolubility and cholesterol depletion methods used to infer the presence of rafts in cells is also discussed. Possible modifications of these techniques that may increase their reliability are considered. It will be necessary to study model membrane systems more closely approximating cell membranes in order gain a complete understanding of raft properties in cells. Very high concentrations of membrane cholesterol and proteins may explain key physical characteristics of domains in cellular membranes, and are the two of the most obvious factors requiring additional study.

Animals↗
PubMed2006

The Burgundy-blood phenomenon: a model of buoyancy change explains autumnal waterblooms by Planktothrix rubescens in Lake Zürich.

Buoyancy changes of the cyanobacterium Planktothrix rubescens- the Burgundy-blood alga - were modelled from its buoyancy response to light and irradiance changes in Lake Zürich during autumnal mixing. The daily insolation received by filaments at fixed depths and circulating to different depths was calculated from the measured light attenuation and surface irradiance. The active mixing depth, za5, was determined from the vertical turbulent diffusion coefficient, Kz, calculated from the wind speed, heat flux and temperature gradients. The fixed depth resulting in filament buoyancy, zn, decreased from 13 to 2 m between August and December 1998; the critical depth for buoyancy, zq, to which filaments must be circulated to become buoyant, decreased from >60 m in the summer to <10 m in winter. When za5 first exceeded zn, in September, P. rubescens was mixed into the epilimnion. In October, zq > za5: circulating filaments would have lost buoyancy in the high insolation. Often in November and December, after deeper mixing and lower insolation, za5 > zq: filaments would have become buoyant but would have floated to the lake surface (the Burgundy-blood phenomenon) only under subsequent calm conditions, when Kz was low. The model explains the Burgundy-blood phenomenon in deeper lakes; waterblooms near shallow leeward shores arise from populations floating up in deeper regions of the lake.

Cyanobacteria↗
PubMed2002

Epileptic fast activity can be explained by a model of impaired GABAergic dendritic inhibition.

This paper focuses on high-frequency (gamma band) EEG activity, the most characteristic electrophysiological pattern in focal seizures of human epilepsy. It starts with recent hypotheses about: (i) the behaviour of inhibitory interneurons in hippocampal or neocortical networks in the generation of gamma frequency oscillations; (ii) the nonuniform alteration of GABAergic inhibition in experimental epilepsy (reduced dendritic inhibition and increased somatic inhibition); and (iii) the possible depression of GABA(A,fast) circuit activity by GABA(A,slow) inhibitory postsynaptic currents. In particular, these hypotheses are introduced in a new computational macroscopic model of EEG activity that includes a physiologically relevant fast inhibitory feedback loop. Results show that strikingly realistic activity is produced by the model when compared to real EEG signals recorded with intracerebral electrodes. They show that, in the model, the transition from interictal to fast ictal activity is explained by the impairment of dendritic inhibition.

Action Potentials↗
PubMed1990

Xenon kinetics in muscle are not explained by a model of parallel perfusion-limited compartments.

Experimental tissue gas kinetics do not follow the prediction for a single stirred perfusion-limited compartment. One hypothesis proposes that the kinetics might be explained by considering the tissue as a collection of parallel compartments, each with its own flow, reflecting the tissue microcirculatory flow heterogeneity. In this study, observed tissue gas kinetics were compared with the kinetics predicted by a model of multiple parallel compartments. Gas exchange curves were generated by recording the time course of tissue radioactivity in the intact calf muscles of anesthetized ventilated dogs exposed to step function changes of 133Xe in the inspired air for 5-h periods. Microcirculatory flow heterogeneity in the same tissue was determined by the radioactive microsphere method. Observed mean tissue transit times were on average longer than predicted by a factor of 6.7. Observed means averaged 52.1 min compared with 8.3 min predicted by the perfusion-limited model. Relative dispersions of tissue transit times were also uniformly larger than predicted. We conclude that Xe gas kinetics in intact canine skeletal muscle are not explained by a model of multiple parallel perfusion-limited compartments. Countercurrent exchange of gas between vessels is a possible explanation.

Animals↗