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Biomedical subjects

M Cannon

Publications and source records attributed to M Cannon.

At least 19 recordsLinked to original sources
PubMed1998

Perception of timing of kinesthetic stimuli.

A psychophysical method was used to estimate the timing of perception of kinesthetic stimuli with different velocities in normal volunteers. A 1 ms auditory click occurred randomly before or after an imposed flexion movement at either 20, 40 or 60 deg/s of the metacarpophalangeal joint. Subjects reported whether the click was perceived before or after the movement onset (experiment 1) or perception of movement velocity (experiment 2). The time at which there was a 50% chance that subjects reported movement or velocity perception after the click was taken as an estimate of the time subjects perceived the stimuli. The difference in time of perceived movement velocity discrimination and movement onset was only significant when the velocity was 20 deg/s (52 ms). This suggests that movement onset and identification of the velocity of the faster movements are perceived nearly simultaneously.

Acoustic Stimulation↗
PubMed1998

Pneumocystis carinii mutations associated with sulfa and sulfone prophylaxis failures in AIDS patients.

BACKGROUND: Failures of prophylaxis against Pneumocystis carinii pneumonia (PCP) in AIDS patients do occur, but no evidence for drug resistance has yet been presented. OBJECTIVE: To determine whether mutations in the sulfa and sulfone drug target are associated with failure of prophylaxis using a sulfa-containing agent. METHODS: Portions of the gene for P. carinii dihydropteroate synthase (DHPS), the sulfa and sulfone target, from 27 patients (20 of whom had AIDS) diagnosed with PCP between 1976 and 1997 were amplified using polymerase chain reaction and sequenced. Seven of the 27 patients (all of whom had AIDS) were receiving sulfa or sulfone drugs as prophylaxis for PCP. RESULTS: Mutations were found at only two amino-acid positions and were significantly more common in patients who received sulfa/sulfone prophylaxis. Mutations were observed in five (71%) out of seven isolates from AIDS patients receiving sulfa/sulfone as prophylaxis compared with only two (15%) out of 13 specimens from AIDS patients who did not (P = 0.022). No mutations were seen in isolates from seven non-HIV-infected patients, none of whom were on prophylaxis. Mutations were only observed in specimens obtained in 1995-1997. CONCLUSIONS: Mutations in two amino-acid positions were significantly more common in AIDS patients with PCP who failed sulfa/sulfone prophylaxis. These amino acids appeared to be directly involved in both substrate and sulfa binding, based on homology to the Escherichia coli DHPS crystal structure. Thus, the results were consistent with the possibility that mutations in the P. carinii DHPS are responsible for some of the failures of sulfa/sulfone prophylaxis in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1998

Obstetric complications and familial morbid risk of psychiatric disorders.

Obstetric complications (OCs) have been found to occur in higher frequency in patients with schizophrenia. One explanation for this finding is that the genes that contribute to the schizophrenia phenotype also influence the likelihood to experience OCs. If this were true, morbid risk of psychiatric illness should be higher in the first-degree relatives of both schizophrenic and control probands exposed to OCs, compared to probands not exposed to OCs. We set out to test this hypothesis. Information on OCs, blind to family history of psychiatric disorder, was collected retrospectively through maternal interview in 151 psychotic patients and 100 controls. Family history (FH) in relatives of cases (n = 600) and controls (n = 461) was assessed with the FH-RDC and through personal interviews. Tests for associations between family history and OCs were conducted using Cox proportional hazard regression. In the cases, familial morbid risk of affective disorder was greater in those with a history of OCs (hazard ratio (HR) = 1.9, P = 0.007). Analyses examining individual complications revealed associations between FH of affective disorder and pre-eclampsia (HR = 2.9, P = 0.003) and FH of affective disorder and breech presentation (HR = 2.8, P = 0.02), especially when family history in the relatives was confined to affective illness in the mother (HR pre-eclampsia = 4.4, P = 0.009; HR breech-presentation = 4.2, P = 0.008). In controls, affective illness in the mother was not only associated with breech presentation (HR = 7.0, P = 0.01) and pre-eclampsia (HR = 4.4, P = 0.03) but also with other complications. Familial morbid risk of schizophrenia and related psychoses was not associated with OCs. The positive associations between OCs and familial morbid risk of affective disorder suggest that the factors that contribute to familial aggregation of affective symptoms in psychotic patients also influence the likelihood to experience OCs. Although the proportion of OCs that could be attributed to these factors was very small, part of the relationship between family history of affective disorder and psychosis may be mediated by OCs.

Age of Onset↗
PubMed1998

The new epidemiology of schizophrenia.

A confluence of findings from different vantage points has led to renewed interest and direction in the epidemiology of schizophrenia. This article provides an overview of prevalence and incidence data, examining the validity of reported secular trends in the occurrence of schizophrenia. Advances in molecular genetics have uncovered new linkage on chromosomes 6, 8, and 22 and have suggested complex models, including anticipation, to explain the perpetuation of genetic transmission in the face of low fecundity. Neurotropic viruses and autoimmunity have emerged as pathoplastic mechanisms to explain recent intriguing epidemiologic associations in schizophrenia. Environmental risk factors are also important. With attention to particular risk factors (i.e., perinatal hypoxia), a preventative approach may be realistic for some forms of schizophrenia.

Developed Countries↗
PubMed1997

Childhood laterality and later risk of schizophrenia in the 1946 British birth cohort.

An increased rate on non-righthandedness and other abnormalities of lateralization have been reported in schizophrenia. We investigated childhood hand preference and eye dominance as risk factors for adult schizophrenia among a general population birth cohort. Pre-schizophrenic children showed a significant excess of left-eye dominance at age 11 when compared with controls (OR 2.5, 1.0-5.8, p = 0.03), but there was no significant difference in hand preference between pre-schizophrenic children and controls.

Brain↗
PubMed1997

IGF-I induces collagen and IGFBP-5 mRNA in rat intestinal smooth muscle.

Insulin-like growth factor (IGF) binding protein 5 (IGFBP-5) mRNA was studied in intestines of rats with peptidoglycan-polysaccharide enterocolitis by Northern analysis and in situ hybridization. IGFBP-5 mRNA was increased 2.4 +/- 0.5-fold in inflamed rat colon compared with controls and was highly expressed in smooth muscle. Cultured rat intestinal smooth muscle cells were used to study the regulation of IGFBP-5 and type I collagen synthesis. IGF-I (100 ng/ml) increased IGFBP-5 mRNA (1.9 +/- 0.1-fold) and collagen type alpha1(I) mRNA (1.6 +/- 0.2-fold) in cultured smooth muscle cells. IGF-I induced a dose- and time-dependent increase in IGFBP-5 in conditioned medium by Western ligand blot and by immunoblot. IGF-I did not affect the IGFBP-5 mRNA decay rate after transcriptional blockade. Cycloheximide abolished IGFBP-5 mRNA. In conclusion, IGFBP-5 mRNA is expressed by intestinal smooth muscle and is increased during chronic inflammation. IGF-I increases IGFBP-5 and collagen mRNAs in intestinal smooth muscle cells.

Animals↗
PubMed1997

Premorbid social functioning in schizophrenia and bipolar disorder: similarities and differences.

OBJECTIVE: This research examined social functioning in childhood and adolescence among patients with schizophrenia and patients with bipolar disorder compared with healthy subjects and investigated the relation between premorbid adjustment and risk factors for psychosis. METHOD: Maternal recall was used to assess the premorbid adjustment of patients with schizophrenia (N = 70) and patients with bipolar disorder (N = 28) recruited from a survey of consecutive hospital admissions for psychosis and of healthy comparison subjects (N = 100) drawn from the same catchment area. RESULTS: The patients with schizophrenia had significantly poorer premorbid adjustment in childhood and adolescence than the comparison subjects and were impaired in both sociability and school adjustment. The patients with bipolar disorder exhibited poorer social impairment in adolescence than the comparison subjects, though to a lesser degree than the schizophrenic subjects, but functioned well at school. There were significant linear trends in the risk of psychosis with worsening premorbid functioning, which was most marked in the schizophrenic group, and a specific linear relation between low birth weight and poor premorbid adjustment among the schizophrenic patients. CONCLUSIONS: Impaired premorbid social functioning is not specific to schizophrenia and is seen also in bipolar disorder. The data support the view that poor premorbid social adjustment is one manifestation of vulnerability to adult psychotic disorders. These results are consistent with other findings pointing to early developmental deficits in patients who subsequently develop psychosis.

Adolescent↗
PubMed1996

Autoimmune diseases in the pedigrees of schizophrenic and control subjects.

Autoimmune diseases aggregate in individuals and within pedigrees, and it has been postulated that autoimmune mechanisms may account for a proportion of schizophrenia. Structured questionnaires were used to interview the mothers of 121 DSM-III-R schizophrenic patients and the mothers of 116 controls in order to determine the prevalence of schizophrenia and of autoimmune diseases in their pedigrees. Patients with a schizophrenic first degree relative were significantly more likely to also have a parent or sibling with an autoimmune disease (60% vs. 20%, OR = 6.1, 95% CI = 2.3-6.5, p = 0.0003). A significant excess of insulin dependent diabetes mellitus (IDDM) was present in the parents and siblings of schizophrenic patients (OR = 9.65, 95% CI = 1.3-429.2, p = 0.009). These findings suggest that autoimmune mechanisms may play a role in the aetiology of schizophrenia, particularly familial schizophrenia. Associations have been established between autoimmune diseases and the HLA encoding genes of the major histocompatibility complex on chromosome six, and it may be that some of the genetic liability to schizophrenia involves these genes.

Adult↗
PubMed1996

Family history of autoimmune diseases in psychosis.

The mothers of 101 psychotic patients and 116 normal controls were interviewed using a semi-structured questionnaire designed to determine the presence or absence of autoimmune disorders in first degree relatives of the probands. Thyrotoxicosis and insulin-dependent diabetes mellitus were significantly more common in the relatives of the psychotic patients than in the control relatives; in particular thyrotoxicosis was more frequent in the mothers of patients (11%) than the mothers of controls (2.6%). None of the examined characteristics of the patients, including RDC-diagnosis, family history of psychosis, age at onset of psychosis and winter birth, was predictive of thyrotoxicosis and insulin-dependent diabetes mellitus in relatives.

Adolescent↗
PubMed1996

Schizophrenia.

Explore the source record for details and available documents.

Age Factors↗
PubMed1996

Mixed-handedness in patients with functional psychosis.

BACKGROUND: An excess of non-right-handedness has been shown among patients with schizophrenia. However it is not clear whether this finding can be accounted for by an increase in left-handedness, mixed-handedness or both. It is not known whether atypical patterns of hand preferences occur in other functional psychotic illnesses. METHOD: The Annett hand preference questionnaire was administered to patients with schizophrenia (n = 120); affective psychosis (n = 55); schizoaffective psychosis (n = 41), and control subjects (n = 86). Handedness was classified into three categories: right, mixed and left-handedness. RESULTS: The hand preference patterns of patients with functional psychotic illnesses were not significantly different from controls. Patients with schizophrenia showed a non-significant excess of mixed-handedness compared with controls. Patients with schizophrenia and affective psychosis showed a non-significant decrease in left-handedness compared with controls. CONCLUSIONS: Although our results showed a trend in the hypothesised direction, we failed to demonstrate that patients with psychotic illness differed from controls on self-reported hand preference patterns.

Adult↗
PubMed1996

Prenatal exposure to the 1957 influenza epidemic and adult schizophrenia: a follow-up study.

BACKGROUND: We investigated the hypothesis that prenatal exposure to the 1957 A2 influenza increases the risk of schizophrenia in adulthood. METHOD: We traced a cohort of individuals known to have been exposed to the 1957 influenza epidemic during gestation and an unexposed cohort matched for period of gestation and hospital of birth. Follow-up information on psychiatric illness in subjects was sought from two sources: maternal interview and psychiatric hospital admission data. RESULTS: Follow-up information was obtained on 54% of the sample: 238 subjects from the influenza-exposed group and 287 subjects from the unexposed group. There was no increased risk of schizophrenia among the exposed cohort compared to the unexposed cohort (relative risk 1.1; 95% Cl 0.41-2.95), although there was an increase in depressive illness (relative risk 1.59; 95% Cl 1.15-2.19). CONCLUSIONS: The association between prenatal influenza and an increased risk of schizophrenia in adulthood has thus far been found only in population-based data and is not supported by the present observational study which has information about exposure and outcome in individuals.

Cohort Studies↗
PubMed1995

Prevalence and correlates of mixed-handedness in schizophrenia.

Increased rates of nonright-handedness have been reported in schizophrenia, but a clear distinction has not been made between left- and mixed-handedness. Handedness preferences in 96 patients fulfilling DSM-III criteria for schizophrenia and 43 normal comparison subjects were assessed with the Edinburgh Handedness Inventory. A 100% criterion was used to establish left- and right-handedness. Results were analyzed with mantel-Haenszel odds ratios adjusted for age and sex. The schizophrenic group showed a significant increase in the proportion of mixed-handers compared with the normal group. There was no increase in pure left-handedness in the schizophrenic relative to the normal group. Mixed-handedness in the schizophrenic patients was significantly associated with chronicity of illness. Mixed-handed patients were less likely to have a family history of psychotic illness than patients with strong right- or left-handedness. The results indicate a neurodevelopmental rather than a genetic origin for anomalous lateralization in schizophrenia.

Adult↗
PubMed1994

Further evidence for anomalies in the hand-prints of patients with schizophrenia: a study of secondary creases.

Finger and palm prints from 46 ICD-9 schizophrenic patients and 43 age and sex matched normal controls were examined independently and blind to diagnosis, by four raters. Seven prints were judged to have very high densities of secondary creases. These abnormal prints were all from the schizophrenic group. Patients with high densities of creases were more severely ill, having had more than five admissions to hospital and higher doses of neuroleptic medication. There was a trend for such patients to have had a complicated obstetric history and an earlier onset of their illness.

Adult↗