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Biomedical subjects

J A Buchanan

Publications and source records attributed to J A Buchanan.

At least 19 recordsLinked to original sources
PubMed2004

Employment of 16 S rDNA gene sequencing techniques to identify culturable environmental eubacteria in a tertiary referral hospital.

Universal or 'broad-range' eubacterial polymerase chain reaction (PCR) was performed on 53 isolates from environmental water-associated sites in a haematology unit (N = 22) and the outer surfaces of cleaning lotion containers sited throughout a tertiary referral hospital (N = 31) 16 S rDNA PCR was performed using two sets of universal primers, including the novel reverse primer, XB4, to generate a composite amplicon of 1068 bp, which was sequenced to obtain each isolate's identity. Sequence analysis was able to identify 51 isolates. Most (75% from the haematology unit and 81% from cleaner containers) were Gram-positive. Nine different genera were identified from the haematology unit and 13 from the cleaning lotion containers. This study provides the first reports of Terrabacter spp. and Brachybacterium paraconglomeratum isolated from a hospital environment. As unusual and difficult-to-identify environmental organisms are unlikely to be clinically significant, and molecular identification is costly and labour-intensive, we recommend that molecular methods are only used as an adjunct to first-line phenotypic identification schemes where a definitive identification is required. Where molecular identification methods are justified, partial 16 S rDNA PCR and sequencing employing the novel universal primer XB4, is a valuable and reliable technique.

Actinomycetales↗
PubMed2003

Spatial working memory ability is a marker of risk-for-psychosis.

BACKGROUND: Working memory has been identified as a core cognitive deficit in schizophrenia that is associated with negative symptoms, but it is unclear whether it is impaired prior to onset of psychosis in symptomatic patients. METHOD: Thirty-eight young people at ultra high-risk (UHR) of developing psychosis (of whom nine later became psychotic) were compared with 49 healthy controls on tests of spatial working memory (SWM) and delayed matching-to-sample (DMTS). RESULTS: Both SWM and DMTS performance was significantly poorer in the UHR groups. Those who later became psychotic generally performed more poorly than those who did not, although this did not reach significance for any measure. A significant association between SWM errors and negative symptoms was seen in the later-psychotic group only (P = 0.02). CONCLUSIONS: Spatial working memory abilities are impaired in those at high-risk for psychosis. The relationship between working memory and negative symptoms may be useful as a predictive tool.

Adolescent↗
PubMed2002

A new frameshift mutation encoding a truncated amelogenin leads to X-linked amelogenesis imperfecta.

The amelogenin proteins are the most abundant organic components of developing dental enamel. Their importance for the proper mineralization of enamel is evident from the association between previously identified mutations in the X-chromosomal gene that encodes them and the enamel defect amelogenesis imperfecta. In this investigation, an adult male presenting with a severe hypoplastic enamel phenotype was found to have a single base deletion at the codon for amino acid 110 of the X-chromosomal 175-amino acid amelogenin protein. The proband's mother, who also has affected enamel, carries the identical deletion on one of her X-chromosomes, while the father has both normal enamel and DNA sequence. This frameshift mutation deletes part of the coding region for the repetitive portion of amelogenin as well as the hydrophilic tail, replacing them with a 47-amino acid segment containing nine cysteine residues. While greater than 60% of the protein is predicted to be intact, the severity of this phenotype illustrates the importance of the C-terminal region of the amelogenin protein for the formation of enamel with normal thickness.

Adult↗
PubMed2002

Visuospatial memory and learning in first-episode schizophreniform psychosis and established schizophrenia: a functional correlate of hippocampal pathology?

BACKGROUND: Despite a number of studies that have indicated impaired memory function in patients with schizophrenia, there have been few that have used a sensitive measure of right medial temporal lobe pathology. Given the reported findings of reduced hippocampal volume in schizophrenia, we used a theoretically sensitive test of the right medial temporal lobe to determine the nature of the visuospatial memory deficit in the disorder. METHODS: Seventy-six patients (37 with a first-episode schizophreniform psychosis, and 39 with established schizophrenia) were compared with 41 comparison subjects on a number of tests of visuospatial memory. These included spatial working memory, spatial and pattern recognition memory and a pattern-location associative learning test. RESULTS: Both patient groups displayed recognition memory deficits when compared to the comparison group. However, only those patients with established schizophrenia (of 9 years duration on average) were impaired on the associative learning test. CONCLUSIONS: The results indicate either a progressive decline in visuospatial associative learning ability over the course of the disorder, or that poor visuospatial associative learning is a marker for poor prognosis. In addition, these results have implications for our understanding of the role of the right medial temporal lobe in the pathophysiology of schizophrenia.

Adolescent↗
PubMed2001

Systemic lupus erythematosus presenting with oral mucosal lesions: easily missed?

Two caucasian patients are described in whom oral mucosal lesions were the first manifestation of systemic lupus erythematosus. In both cases the diagnosis was delayed despite histological examination of oral lesions. Treatment with antimalarials and azathioprine was of significant benefit. In the absence of cutaneous or systemic features, distinguishing oral lupus erythematosus from lichen planus and epidermal dysplasia can be difficult, both clinically and on histology, and requires a high index of suspicion.

Adult↗
PubMed2001

Use of simulation technology in dental education.

Simulation is becoming very beneficial in the area of health care education. Dentistry has used various types of simulation in preclinical education for some time. This article discusses the impact of the current simulation laboratories on dental education and reviews advanced technology simulation that has recently become available or is in the developmental stage. The abilities of advanced technology simulation, its advantages and disadvantages, and its potential to affect dental education are addressed.

Computer Simulation↗
PubMed2000

Delayed and immediate hypersensitivity reactions associated with the use of amalgam.

Hypersensitivity to the constituents of dental amalgam is uncommon. When it occurs it typically manifests itself as a lichenoid reaction involving a delayed, type IV, cell-mediated hypersensitivity response. Rarely, a more acute and generalised response can occur involving both the oral mucosa and skin. We describe two cases that illustrate the presentation and management of these two types of reaction.

Blister↗
PubMed2000

Characteristics of empirically supported treatments.

This study presents a survey of general characteristics of empirically supported treatments (ESTs) identified by the American Psychological Association Division 12 Task Force on the Promotion and Dissemination of Psychological Procedures. Results indicate that the ESTs share the following characteristics: they involve skill building, have a specific problem focus, incorporate continuous assessment of client progress, and involve brief treatment contact, requiring 20 or fewer sessions. Traditional assessment methods, such as intelligence testing, projectives, and objective personality tests such as the MMPI-2, are rarely used in these treatments. Although it is recognized that these findings are in part an artifact of sociological factors present in contemporary psychotherapy development and research, the findings may also serve as a heuristic aid in the development of therapies.

Behavior Therapy↗
PubMed1999

Role of human papillomaviruses in cutaneous and oral manifestations of immunosuppression.

Long-term immunosuppressive drug regimes, used to prevent organ transplant rejection, are associated with an increased risk of epithelial malignancies particularly anogenital and cutaneous cancers. Premalignant and malignant lesions of the oral mucosa have also been reported in renal transplant recipients (RTRs), particularly of sun-exposed lip lesions. Many of these anogenital lesions are associated with the detection of high-risk mucosal human papillomaviruses (HPV). Novel degenerate and nested polymerase chain reaction (PCR) techniques have found high levels of epidermodysplasia verruciformis (EV) HPVs (high-risk cutaneous oncogenic HPVs) in cutaneous warts, dysplastic keratoses, and squamous cell carcinomas. Unusual appendageal and spindle cell carcinomas are being observed in RTRs. Increasing survival times of HIV-positive patients may be associated with dysplasia of orogenital mucosal epithelium, and careful epidemiologic studies of cutaneous lesions are needed. The role of HPVs in the development of these lesions has yet to be established.

Adult↗
PubMed1998

Investigation of dopamine system genes in obsessive-compulsive disorder.

Evidence from anatomical, pharmacological, and animal studies on the involvement of the dopamine system in obsessive-compulsive disorder (OCD) is mounting. This, along with evidence for a genetic diathesis provided by family and twin studies, prompted us to conduct genetic association studies of dopamine system genes in OCD. We genotyped OCD patients (n > 100) and matched controls for four loci: (1) a 40-base-pair repeat in the dopamine transporter gene; (2) the TaqIA polymorphism and the serine/cysteine variation in the D2 dopamine receptor gene; (3) an MscI polymorphism in the D3 dopamine receptor gene; and (4) a 48-base-pair repeat in the D4 dopamine receptor gene. Significant differences in allele frequencies were found between patients and controls for the D4 receptor gene, although replication is required with family-based controls before any conclusions can be entertained. This study represents the first comprehensive assessment of the roles of dopamine system genes in OCD.

Age of Onset↗
PubMed1998

Prototypes of intrafamily homicide and serious assault among insanity acquittees.

Public concern with societal violence is intensified when persons who have been found not guilty by reason of insanity (NGRI) of having committed a homicide or serious assault are returned to the community. Successful management of such acquittees in the community requires a sophisticated understanding of the person and the illness within the larger context of the violent incident, the family, the community, and the culture. In this article, we present an analysis of psychotic violence within a family context. A qualitative study of 64 subjects who were found NGRI of killing or seriously injuring a family member resulted in four prototypes of intrafamilial homicide/assault: Till Death Us Do Part; Overwhelming Burden, Elimination of the Limit Setter; and Family-Focused Delusional Killing. The prototypes are presented as a model for developing management strategies both for future risk assessment and for successful transition of the insanity acquittee into the community.

Adolescent↗
PubMed1998

Factors associated with weapon use in maternal filicide.

The objective of this study was to identify factors associated with weapon use in a group of filicidal women. Clinical data were gathered from the charts of sixty filicidal women evaluated at Michigan's Center for Forensic Psychiatry or through Connecticut's Psychiatric Security Review Board from 1970 to 1996. Factors associated with weapon use were determined using chi squares, ANCOVAS, and a logistic regression. Results were compared to national statistics for child homicide from the Department of Justice Uniform Crime Reports (UCR). Weapon was defined as knife or gun for the study. Weapons were used by one of four women in our study. Guns were used by 13% of filicidal women and knives by 12%. Odds ratio showed that psychotic women were eleven times more likely to kill their child with a weapon than their non-psychotic counterparts (11.2; p = .008). Psychosis was present in every mother who killed her child with a knife and in seven of eight women who killed their children with a gun. Younger children were less likely to be killed with weapons (ANCOVA; F = 8.28; p = .006). This finding was independent of presence or absence of maternal psychosis. These results show that psychotic women are more likely than non-psychotic women to kill their children with weapons. They also show that mothers are more likely to use weapons to kill older children than younger children.

Adolescent↗
PubMed1997

Transfer between atropine-induced spiking in the perirhinal cortex and electrical kindling of the amygdala.

We have recently determined that microinfusions of atropine sulphate into the perirhinal cortex (PRC) of adult Sprague-Dawley rats result in the dose dependent generation of epileptiform spike activity. Several observations suggested that atropine-induced spiking (AIS) and amygdaloid kindled seizures may share common neuronal mechanisms: (a) PRC atropine infusions occasionally resulted in the development of generalised seizures resembling those produced by amygdaloid kindling and which were accompanied by simultaneous discharge recorded from the PRC and amygdala, and (b) concurrent low amplitude spiking was occasionally recorded from the amygdala during non-seizure inducing infusions. Using kindling transfer, the present study sought to determine whether AIS possesses some epileptogenic characteristics which are common to an electrically generated afterdischarge. Repeated PRC infusions of atropine sulphate supra-threshold for the elicitation of spiking appeared to produce a positive transfer in that significantly more advanced behavioural seizures were elicited during initial amygdaloid kindling. These findings suggest that AIS (and/or atropine-induced behavioural seizures) and amygdala-kindled seizures share, at some level, common neuronal mechanisms.

Amygdala↗
PubMed1997

Transfer of epileptogenesis between perirhinal cortex and amygdala induced by electrical kindling.

An interesting feature of the kindling phenomenon relates to the finding that kindling established in one region of the brain may reduce the number of stimulations required to establish the phenomenon in a second region. It has been proposed that this 'transfer' phenomenon reflects the extent to which seizures arising in two distinct regions share common underlying mechanisms. The perirhinal cortex (PRC) is currently receiving considerable attention with regard to its possible role in epileptogenesis. Although the role of this region in limbic seizures is unclear, the existence of reciprocal connections between the PRC and amygdala provides a possible neural substrate through which these two regions may influence one another. On the basis of this connectivity, one might expect a transfer between PRC kindling and amygdaloid kindling. Using kindling transfer, the present study was formulated to determine the nature of the relationship between electrical kindling of the PRC and amygdala. Animals previously kindled from the PRC to a cortico-generalised level displayed significantly more advanced behavioural seizures during the early stages of amygdaloid kindling than either controls or those partially kindled. This suggests that primary PRC kindling may facilitate amygdaloid access to systems responsible for the generation of motor seizures. Thus, in terms of kindling, the PRC and amygdala appear to be functionally related, with generalised seizures elicited from the PRC and amygdala sharing, at some level, common underlying mechanisms. Finally, the finding that seizures kindled from the dorsal component of the PRC tended to exhibit characteristics which were quite distinct from those elicited by ventral PRC kindling suggests that these two subregions may have different kindling characteristics and/or different patterns of connectivity with the amygdaloid complex.

Amygdala↗
PubMed1997

Golgi membrane skeleton: identification, localization and oligomerization of a 195 kDa ankyrin isoform associated with the Golgi complex.

To extend our finding of a Golgi-localized form of the membrane skeleton protein spectrin, we have identified an isoform of ankyrin that associates at steady state with the Golgi complex. Immuno-light and -electron microscopy show that this ankyrin isoform localizes to the perinuclear cytoplasm on tubular vesicular structures that co-stain with Golgi marker proteins. An antiserum raised against erythrocyte ankyrin, which was used to identify the Golgi ankyrin, recognized three prominent polypeptides of 220, 213 and 195 kDa in MDCK cells. Affinity purification of this antiserum against each of these MDCK cell ankyrins revealed that only an antibody specific for the 195 kDa form retained the ability to stain the Golgi complex; affinity purified antibody preparations specific for both the 220 and 213 kDa forms stained punctate and reticular cytoplasmic structures distinct from the Golgi complex. Antibody specific for the 195 kDa ankyrin did not recognize a recently identified 119 kDa ankyrin that is also localized to the Golgi. The 195 kDa Golgi ankyrin binds purified erythrocyte spectrin, and rapidly co-sediments with Golgi beta-spectrin during brief, low speed centrifugation of Triton X-100 extracts of MDCK cells. Golgi ankyrin and beta-spectrin are retained on tubular vesicular 'Golgi ghosts' following extraction of cultured cells with Triton X-100. Significantly, Golgi ghost tubules containing ankyrin/spectrin are co-linear with individual microtubules, suggesting a role for both Golgi membrane skeleton and microtubules in spatial localization of the Golgi. Golgi ankyrin dissociates from Golgi membranes during mitosis and in cells treated with brefeldin A, indicating that Golgi ankyrin has a dynamic assembly state similar to that of Golgi spectrin and other Golgi membrane coat proteins.

Animals↗
PubMed1995

Association study of dopamine D3 receptor gene and schizophrenia.

Several groups have reported an association between schizophrenia and the MscI polymorphism in the first exon of the dopamine D3 receptor gene (DRD3). We studied this polymorphism using a North American sample (117 patients plus 188 controls) and an Italian sample (97 patients plus 64 controls). In the first part of the study, we compared allele frequencies of schizophrenia patients and unmatched controls and observed a significant difference in the total sample (P = 0.01). The second part of the study involved a case control approach in which each schizophrenia patient was matched to a control of the same sex, and of similar age and ethnic background. The DRD3 allele frequencies of patients and controls revealed no significant difference between the two groups in the Italian (N = 53) or the North American (N = 54) matched populations; however, when these two matched samples were combined, a significant difference was observed (P = 0.026). Our results suggest that the MscI polymorphism may be associated with schizophrenia in the populations studied.

Alleles↗