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Biomedical subjects

A H Thompson

Publications and source records attributed to A H Thompson.

At least 19 recordsLinked to original sources
PubMed2001

Prevalence of mental disorders in children living in Alberta, Canada, as determined from physician billing data.

BACKGROUND: The prevalence of mental disorders is often assessed using survey techniques. Although providing good estimates of prevalence, these techniques are time-consuming and expensive. OBJECTIVE: To estimate the prevalence of mental disorders among children aged 0 to 17 years living in Alberta, Canada, using health care administrative data. DESIGN: This was a cross-sectional study. International Classification of Diseases, Ninth Revision, Clinical Modification chapter 5 diagnostic codes from physician billing data were used. Codes were grouped into 10 categories. Prevalence rates for each category were calculated, stratified by age, sex, and premium subsidy status (a proxy for socioeconomic status). The age pattern, times of greatest risk, and the effect of sex on type and prevalence of mental disorder were estimated. SETTING: All fee-for-service health care venues in Alberta between April 1, 1995, and March 31, 1996, providing services to children registered with the Alberta Health Care Insurance Commission on March 31, 1996. RESULTS: Prevalence of mental disorders varied by disorder category, age, sex, and premium subsidy status. For boys, maximum prevalence of 9.5% occurred at age 10 years; for girls, maximum prevalence of 12.0% occurred at age 17 years. Mental disorders were most common in young boys and adolescent girls and among children receiving welfare. Distinct patterns of disorder were evident and comorbidity was common. CONCLUSIONS: Administrative data can be used to estimate the prevalence of mental disorders in a pediatric population. The estimates made are lower than those obtained by using surveys of similar populations, perhaps indicating the difference between treated and untreated prevalence. Strengths of this study are that the estimates reflect the entire population, are more easily and obtained at less cost, and are useful for the planning of mental health services.

Accounts Payable and Receivable↗
PubMed2001

A social problem index for Canada.

OBJECTIVE: To construct an index that represents the general level of social problems among Canadian provinces and territories. METHOD: Factor weights were used to combine provincial and territorial rates for homicide, attempted murder, assault, sexual assault, robbery, divorce, suicide, and alcoholism into a single Social Problem Index. RESULTS: The resulting index demonstrated strong positive intercorrelations among its factors across provinces. That is, provinces that showed high rates on one factor tended to show high rates on the others as well. The validity of the Social Problem Index is demonstrated by its positive correlation with an independent measure of the likelihood of having experienced personal trauma. CONCLUSIONS: The robust nature and apparent validity of the Social Problem Index suggest that it can be well used for needs assessments and theoretical studies and as a feedback mechanism to national, provincial, and community leaders on the social problem status of their particular jurisdictions.

Canada↗
PubMed1999

Heterogeneous cytokine production by acutely stimulated bronchoalveolar T lymphocytes in reovirus 1/Lang-infected mice.

While the in vitro properties of CD4(+) and CD8(+) cytokine-producing lymphocytes have been well studied, the in vivo cytokine production patterns and relative roles of CD4(+) and CD8(+) T lymphocytes during a primary in vivo immune response remain unclear. In this study, mice were inoculated intranasally with reovirus 1/L, and respiratory T lymphocyte populations were analyzed using multicolor flow cytometric analysis for the production of cytokine within and between classical type 1/type 2 patterns. Cytokine production observed in vivo following infection did not correlate with classical T cell cytokine expression patterns; instead, multiple types of lymphocyte populations that produced one of several possible cytokine combinations were present. Cytokine production by CD4(+) lymphocytes appears in the early and middle stages of the immune response, while CD8(+) lymphocytes produce more cytokine in the later stages. Early cytokine responses occurred predominantly in the whole lung and lung-associated lymph node populations. The complex patterns of cytokine expression seen in this study likely influence local cell-mediated immunity as well as the complex interaction of T cell subsets and the interaction of T cells with B cells which are necessary for the generation of cell-mediated and humoral immune responses required for effective broad-spectrum immunity.

Animals↗
PubMed1999

Optimal induction of upper respiratory tract immunity to reovirus 1/L by combined upper and lower respiratory tract inoculation.

There has been an increasing interest in developing vaccines which are both easy to administer and which elicit functionally protective immune responses at mucosal and/or systemic sites. Intranasally administered vaccines meet the criteria of ease of administration and are thought to stimulate respiratory-mucosal immunity via interaction with nasal associated lymphoid tissues (NALT). The aim of this study was to gain a better understanding of how best to stimulate respiratory-mucosal immunity using a murine model of respiratory reovirus infection. Either a predominantly upper respiratory tract infection or a combination upper and lower respiratory tract infection was established by administering the same virus dose in either a small or large inoculum volume. These studies demonstrate that stimulation of NALT alone by an upper respiratory tract infection does not induce an optimal primary antibody response even in the nasal cavity. Effective immunity of both the upper and lower respiratory tract was obtained when a combination upper and lower respiratory tract infection was established. These results have important clinical implications since they suggest that effective respiratory mucosal immunity will be best achieved by the combined stimulation of both the upper and lower respiratory tract and will likely require both intranasal as well as inhaled aerosol delivery of antigen to the lower respiratory tract in humans.

Administration, Intranasal↗
PubMed1999

Self-regulating service delivery systems: a model for children and youth at risk.

A conceptual model of self-regulating service delivery is proposed for use by governments, planners, and policymakers to help children reach optimal adult functioning. It addresses most problems of present service delivery and is applicable to children in the general population and registered consumers of mental health, child welfare, special education, drug dependency, and juvenile justice (young offender) services. It has four essential components: (1) outcome measurements that reflect the mental health statuses of children in services and in the general population; (2) regular feedback of these measurements to governments, the public, and service delivery organizations; (3) powerful and significant rewards and incentives for the most desired outcomes to increase their salience and to motivate provider behavior; and (4) decision making that can affect all entities that contribute to the health of children. The evaluable expected benefits are improved mental health for children and greater efficiency within the "system."

Adolescent↗
PubMed1999

A new factor in youth suicide: the relative age effect.

OBJECTIVE: To determine whether youth in Alberta who had completed suicide were more likely to be younger than their classmates on entering grade 1 (that is, showed a relative age effect). METHOD: Records were obtained for all deaths by suicide by individuals under the age of 20 years in Alberta during the years 1979-1992. The relative age of each of these persons was determined by comparing his or her month of birth to the birth months of the appropriate school-grade cohort. RESULTS: A disproportionate number of the subjects were born in the second half of the "school eligibility year," indicating a higher probability that those who completed suicide were younger than their classmates. CONCLUSIONS: Previous research indicates that relative age is strongly related to school performance and success in sports. The present study demonstrates that the relative age effect is also a factor in youth suicide. It is suggested that the higher incidence of youth suicide in the group of relatively younger school children may have resulted from poorer school performance, which in turn led to lowered confidence and self esteem. Past research suggests that these conditions may predispose children to hopelessness and depression, which are often thought to be essential components of suicide. Research aimed at neutralizing the negative effects of relative age should have important personal and social consequences.

Adolescent↗
PubMed1998

Antibody-forming cells in the nasal-associated lymphoid tissue during primary influenza virus infection.

Antibody-forming cell (AFC) responses in the nasal-associated lymphoid tissue (NALT) of BALB/c mice were examined following intranasal infection, mainly of the upper respiratory tract, with a small volume of influenza virus. The infection induced significant accumulation of T and B cells in NALT, peaking around day 7 post-infection. Virus-specific IgA, IgG and IgM AFC responses were induced, developing from day 5 and peaking at day 7; responses were predominantly IgA and IgG, followed by IgM. At peak, NALT contained the greatest number of IgA AFCs per total cells of the lymphoid tissues examined in the upper respiratory tract. The IgM AFC responses were induced in NALT cell cultures from uninfected mice following in vitro culture with influenza virus, indicating that at least a part of the AFCs in infected mice may have originated from specific B cell precursors in NALT. In parallel with the detection of AFCs in infected mice, virus-specific IgA antibodies appeared in the nasal wash and their appearance correlated well with virus clearance from the nasal area. These results suggest that virus-specific IgA antibodies, produced by IgA AFCs in NALT, play an important role in recovery from infection.

Animals↗
PubMed1997

Isolation and characterization of mouse nasal-associated lymphoid tissue.

A method for isolation of mouse nasal-associated lymphoid tissue (NALT), which is a principal mucosal lymphoid tissue of the respiratory tract in rodents, was developed. The paired lymphoid organs could be separated from the upper jaw by peeling away the palate where NALT was localized bilaterally on the posterior side. About 3 x 10(5) lymphocytes could be obtained from one NALT fragment. The NALT lymphocyte fraction from normal BALB/c mice contained T- and B-cells in about equal numbers, and contained about 4 times as many CD4+ T-cells as CD8+ T-cells when analyzed with a FACScan fluorescence analyzer. The composition of the NALT lymphocytes was similar to that of the lymphocytes from the portion of the nasal cavity remaining after isolation of the NALT. The NALT lymphocyte fraction from mice infected 7 days previously with influenza virus was also characterized. The numbers of NALT T- and B-cells from the infected mice were approximately 2 and 3 times higher than those of non-infected mice, respectively. In parallel with the cell increase, NALT lymphocytes produced IFN-gamma when cultured for 24 h and contained cells secreting influenza virus-specific IgA and IgG antibodies. The results suggest that this method can be successfully used for investigating cellular dynamics of mucosal immunology in the upper respiratory tract.

Animals↗
PubMed1996

Respiratory-mucosal lymphocyte populations induced by reovirus serotype 1 infection.

Respiratory virus infections are a serious health challenge. While models exist to study immune mechanisms of the respiratory tract, they have not allowed analysis of the interaction of the lower respiratory tract with other components of the mucosal immune system. This study demonstrates that reovirus 1/Lang, an effective gut mucosal immunogen, also provides a useful model of respiratory mucosal infection. Intra-nasal infection of Balb/c mice resulted in severe viral bronchopneumonia. Major components of the cellular inflammatory response in the lung interstitium and alveolar spaces were CD8 lymphocytes. Lung lymphocyte populations exhibited lysis of reovirus-infected, but not uninfected target cells after in vitro culture. The GCT antigen, a germinal center B-cell and CD8 T-cell marker, was present on 21-60% of the inflammatory lymphocytes. A novel population of GCT-expressing CD4+ lymphocytes unique to reovirus-stimulated lung alveolar and interstitial lymphocyte populations was identified.

Acute Disease↗
PubMed1996

Experimental reovirus serotype 1/strain Lang infection of the lung: a model for the study of the lung in the context of mucosal immunity.

A number of studies have examined the nature of the respiratory immune response to particular pathogens. Although many pathogens stimulate specific immunity in the lung, they frequently are not effective immunogens at other mucosal sites. Because the gastrointestinal tract is a major inductive site for mucosal immunity, a pathogen that is an effective respiratory and gut immunogen would allow studies of the interaction of the lung with gut mucosal immune system. Reovirus, a respiratory isolate that previously has been shown to be an effective gut mucosal immunogen, provides a potential model of the relationship of the lung to the gut mucosal immune system. In this report, we demonstrate that intranasal application of reovirus serotype 1/strain Lang (1/L) to CD-1 mice elicits an acute lymphocytic inflammatory infiltration of the lung and hyperplasia of the lung-associated lymph nodes. The initial inflammatory response occurs in the airspaces and interstitium of the lung. As the infection progresses, the initially diffuse cellular infiltrate becomes more focused around small bronchioles. Viral replication occurs predominantly during the first week of the infection, and infectious virions are eliminated during the second week. After the elimination of infectious virions, a secondary response consisting of the appearance of plasma cells adjacent to pulmonary arteries develops as the primary infiltrate organizes into peribronchiolar follicles, resembling the human inflammatory lung condition termed follicular bronchiolitis. These two infiltration patterns were also observed by immunohistochemical analysis of the the infected lung. Whereas CD4+ and CD8+ lymphocytes and Mac-1+ cells were found to be more closely associated with the primary infiltration process, B220+ lymphocytes were observed adjacent to pulmonary arteries. These results establish respiratory reovirus 1/L infection as a viable model for future investigations of the mucosal immune response in the lung and its relationship to the common mucosal immune system.

Animals↗
PubMed1995

Social dysfunction and mental illness in a community sample.

The purpose of this study was to determine the extent of the association between psychiatric disorders and various social problems. The Diagnostic Interview Schedule was administered to a community sample of 3258 individuals and the association between eight "core" psychiatric disorders and eight social problem behaviours was determined. The results confirmed findings from many clinical studies that had previously found a strong relationship between social problem behaviours and mental illness. However, certain disorders tended to be associated with specific problems. In addition, a positive association was found between the number of social problems exhibited and the prevalence of psychiatric disorder. These data suggest the presence of a common underlying factor (or factors) and call into question the common practice of creating separate services for each definable social problem that arises.

Adult↗
PubMed1994

Combined proton T1N and CPMG T2N studies of water saturated sandstone core plugs.

Diffusion dynamics for water in a series of sandstone core plugs with a broad range of permeabilities was studied using both the Carr-Purcell-Meiboom-Gill (CPMG) and inversion recovery experiments. Both the transverse and longitudinal magnetization curves were found to fit well to stretched exponential relaxation kinetics. At short times, the transverse magnetization is well described by an expression for free diffusion averaged over a distribution of pore sizes. The stretch exponents for the transverse and longitudinal magnetization are shown to be simply related to the width of the pore size distribution. A cross over from free to restricted diffusion is evident in the dependence of T2 with increasing diffusion time set by the interpulse spacing tau in the CPMG experiment. The T2(tau) data is fit to a model which interpolates between the limits of free and restricted diffusion. A length derived from this model is shown to provide a simple estimate of the absolute fluid flow permeability.

Magnetic Resonance Spectroscopy↗
PubMed1994

Community mental health services' clients with child welfare status.

An examination of two samples of children seen one year apart at a community mental health service indicated that a significant proportion had also been involved with the child welfare system (44% of the 119-member older sample and 32% of the 160 individuals from the current sample). A reanalysis of the latter sample one year later showed that the caseload overlap had increased to 39%.

Adolescent↗
PubMed1993

Accidental poisoning of a group of yearling cattle by the organophosphate insecticide trichloronat.

Eight yearling cattle were accidentally poisoned with the agricultural organophosphate insecticide trichloronat. One animal showed signs of acute organophosphate poisoning and died. The others showed signs of chronic organophosphate poisoning (organophosphate-induced delayed neuropathy) after 2-3 weeks and one animal died from renal failure at 12 weeks. High levels of trichloronat were measured in fat samples at 6 1/2 weeks. The remaining animals still showed signs of ataxia, possibly due to distal axonopathy, 1 year later but no trichloronat was detected in fat samples at this time.

Journal Article↗
PubMed1989

Relationship and chronology of depression, agoraphobia, and panic disorder in the general population.

The comorbidity of disorders and chronology of first symptoms of depression, agoraphobia, and panic disorder were investigated. The Diagnostic Interview Schedule was administered to 3258 household residents. Strong associations were shown among all three disorders. However, the comorbidity of agoraphobia and panic disorder seemed to be accounted for by the relationship of both disorders with depression. The mean age at appearance of first symptoms was earlier for agoraphobia (low teens) than for depression or panic disorder (both about age 20). The results do not support the view that panic disorder is an integral component of agoraphobia, but rather that it is more closely associated with depression. The fact that agoraphobia precedes depression casts doubt on the thesis that depression is primary to anxiety disorders. Interpretation should, however, be viewed with caution because of the retrospective nature of the diagnostic instrument.

Adolescent↗
PubMed1988

Suicide trends in Canada, 1956-1981.

Using official suicide statistics, this study examined suicide rates in Canada over a 25-year span (1956 to 1981) as a function of age, gender, and geographical region. The analysis revealed that, for both sexes, the risk of suicide among the 15-24 year-olds increased at a faster rate than in any other age group. Male and female age-standardized suicide rates demonstrated an overall increase between 1956 and 1981. The trend for males was one of continuous increase, whereas female rates reached a maximum in 1976 and then decreased. Regional differences in suicide rates were also apparent. Although not strictly observed, a trend toward increasing risk of suicide in males as one proceeds westward across Canada was found. For females, a pattern of increasing suicide with more westerly location was also found, except that Ontario and the Prairie Provinces were in reverse order. Several possible explanations for these findings are presented.

Adolescent↗
PubMed1987

An unusual case of neonatal myasthenia.

An unusual case of neonatal myasthenia gravis is reported in an infant who had respiratory failure due to diaphragmatic weakness. Although power and tone in the limbs were normal, fatiguability of both diaphragm and peripheral muscles was demonstrated. Acetylcholine receptor antibodies were absent in the mother, which suggests that an alternative humoral mechanism may have been responsible for the transient (6-week) neonatal weakness.

Female↗