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Biomedical subjects

B Casey

Publications and source records attributed to B Casey.

At least 37 records · Page 2Linked to original sources
PubMed1998

Impact of chronic systemic and neurological disorders on disability, depression and life satisfaction.

OBJECTIVE: To assess the effects of a range of chronic systemic and neurological disorders on three life quality indicators: disability, depressive symptoms and life satisfaction. METHODS: As part of the Sydney Older Persons Study, a community survey was carried out with 434 non-demented people aged 75 or over living in Sydney, Australia. Subjects were given a medical examination covering the following disorders: heart disease, chronic lung disease, bone and joint disease, stroke, visual loss, peripheral vascular disease, obesity, other systemic diseases, gait ataxia, gait slowing (including Parkinsonism) and cognitive impairement short of dementia. They were also assessed on a clinician-rated disability scale and given self-report depression and life satisfaction scales. RESULTS: Gait slowing affected all three indicators of life quality. Heart disease and chronic lung disease affected disability and depressive symptoms, but not life satisfaction. These associations were present when the effects of age, sex, education and all other disorders were controlled in multiple regression analyses. However, when disability was also controlled, none of the physical disorders predicted life satisfaction and only heart disease continued to predict depressive symptoms. CONCLUSION: Of the physical disorders considered in the study, gait slowing, heart disease and chronic lung disease had the greatest impact on life quality. These disorders affect depressive symptoms and life satisfaction largely because they increase disability.

Aged↗
PubMed1998

Genetics of human left-right axis malformations.

Like all vertebrates, humans establish anatomic left-right asymmetry during embryogenesis. Variation from this normal arrangement (situs solitus) results in heterotaxy, expressed either as randomization (situs ambiguus) or complete reversal (situs inversus) of normal organ position. Familial heterotaxy occurs with autosomal dominant, recessive, and X-linked inheritance. All possible situs variants--solitus, ambiguus, inversus--can appear among some heterotaxy families. Positional cloning has led to the identification of a gene on the X chromosome responsible for some cases of human heterotaxy. In addition to their medical relevance, human studies provide a unique contribution to our understanding of left-right axis development among all vertebrates.

Body Patterning↗
PubMed1998

Time saved with use of emergency warning lights and sirens during response to requests for emergency medical aid in an urban environment.

STUDY OBJECTIVE: To determine whether the use of warning lights and sirens saves a significant amount of time for ambulances responding to requests for medical aid in an urban, 2-tiered EMS setting. METHODS: A prospective design was used to determine run times for ambulances responding to calls with lights and sirens (Code 3), and for a similarly equipped "chase" vehicle traveling to the same call on the same route without lights and sirens (Code 2). Data were collected for run times, distance traveled, visibility, road surface condition, time of day, and day of the week. Simple statistics and analysis of variance were used to test for significant differences between Code 3 and Code 2 operation, as well as the other variables listed above. RESULTS: Sixty-four runs were timed during a 9-month period. The average Code 3 response interval was 4.46 minutes. The average Code 2 response interval was 7.48 minutes. The 3.02 minutes saved on average represents a significant time savings of 38.5% (P < .01). Run distance was the only variable that was statistically significant in affecting time saved during a Code 3 response. CONCLUSION: Code 3 operation by EMS personnel in an urban, 2-tiered EMS setting saved significant time over Code 2 operation when traveling to a call.

Ambulances↗
PubMed1998

Two rights make a wrong: human left-right malformations.

Like all vertebrates, humans establish anatomical left-right asymmetry during embryogenesis. Variation from this normal arrangement (situs solitus) results in heterotaxy, expressed either as randomization (situs ambiguus) or complete reversal (situs inversus) of normal organ position. Familial heterotaxy occurs with autosomal dominant, recessive and X-linked inheritance. All possible situs variants, solitus, ambiguus and inversus, can appear among some heterotaxy families. Positional cloning has led to the identification of a gene on the X chromosome responsible for some cases of human heterotaxy. Additional candidate genes have emerged from recent studies of left-right axis development in chick, frog and mouse, which have begun to elucidate a tightly regulated genetic cascade that differentiates the left and right sides prior to the appearance of morphological asymmetry.

Animals↗
PubMed1998

Health habits and risk of cognitive impairment and dementia in old age: a prospective study on the effects of exercise, smoking and alcohol consumption.

Previous research has yielded inconsistent results on the effects of exercise, smoking and alcohol use on cognitive impairment and dementia in old age. We analysed data from the Sydney Older Persons Study to see if these health habits were associated with cognitive functioning, dementia or Alzheimer's disease. Health habits were assessed in Wave 1 of the study, when the subjects were aged 75 years or over. Three years later, the subjects were tested for cognitive functioning and clinically examined for dementia and Alzheimer's disease. The analysis was restricted to the 327 subjects examined in Wave 2 who were non-demented in Wave 1. There were few significant associations between health habits and cognitive performance and these were not found consistently across cognitive measures. No associations were found with dementia or Alzheimer's disease. While these health habits do not affect risk for dementia and cognitive impairment in the very elderly, who are at highest risk for these disorders, we cannot discount a role at younger ages.

Aged↗
PubMed1997

X-linked situs abnormalities result from mutations in ZIC3.

Vertebrates position unpaired organs of the chest and abdomen asymmetrically along the left-right (LR) body axis. Each structure comes to lie non-randomly with respect to the midline in an overall position designated situs solitus, exemplified in humans by placement of the heart, stomach and spleen consistently to the left. Aberrant LR axis development can lead to randomization of individual organ position (situs ambiguus) or to mirror-image reversal of all lateralized structures (situs inversus). Previously we mapped a locus for situs abnormalities in humans, HTX1, to Xq26.2 by linkage analysis in a single family (LR1) and by detection of a deletion in an unrelated situs ambiguus male (Family LR2; refs 2,3). From this chromosomal region we have positionally cloned ZIC3, a gene encoding a putative zinc-finger transcription factor. One frameshift, two missense and two nonsense mutations have been identified in familial and sporadic situs ambiguus. The frameshift allele is also associated with situs inversus among some heterozygous females, suggesting that ZIC3 functions in the earliest stages of LR-axis formation. ZIC3, which has not been previously implicated in vertebrate LR-axis development, is the first gene unequivocally associated with human situs abnormalities.

Amino Acid Sequence↗
PubMed1997

A submicroscopic deletion in Xq26 associated with familial situs ambiguus.

Abnormal left-right-axis formation results in heterotaxy, a multiple-malformation syndrome often characterized by severe heart defects, splenic abnormalities, and gastrointestinal malrotation. Previously we had studied a large family in which a gene for heterotaxy, HTX1, was mapped to a 19-cM region in Xq24-q27.1. Further analysis of this family has revealed two recombinations that place HTX1 between DXS300 and DXS1062, an interval spanning approximately 1.3 Mb in Xq26.2. In order to provide independent confirmation of HTX1 localization, a PCR-based search for submicroscopic deletions in this region was performed in unrelated males with sporadic or familial heterotaxy. A cluster of sequence-tagged sites failed to amplify in an individual who also had a deceased, affected brother. FISH identified the mother as a carrier of the deletion, which arose as a new mutation from the maternal grandfather. The deletion interval spans 600-1,100 kb and lies wholly within the 1.3-Mb region identified by recombination. Discovery of this deletion supports localization of HTX1 to Xq26.2 and reveals the first molecular-genetic abnormality associated with human left-right-asymmetry defects.

Abnormalities, Multiple↗
PubMed1997

Scores on the Group Embedded Figures Test by undergraduates in information management.

The Group Embedded Figures Test was administered to 63 undergraduates in a program for a Bachelor of Applied Arts in Information management. Distribution characteristics, sex differences, reliability, and internal consistency measures for this sample were compared with those for Witkin's original sample. In addition, item difficulty and discrimination coefficients are provided. Scores for this group show desirable measurement characteristics.

Adult↗
PubMed1997

Dermatofibrosarcoma protuberans (DFSP): growth characteristics based on tumor modeling and a review of cases treated with Mohs micrographic surgery.

Dermatofibrosarcoma protuberans (DFSP) is a relatively rare cutaneous tumor that is clinically challenging since it is locally highly invasive and aggressive, although it rarely metastasizes. Traditionally, wide and deep local surgical excision has been regarded as the treatment of choice for DFSP. However, even 3-cm-wide local excision margins have resulted in a local recurrence rate of 11%. In recent years, reports of DFSPs successfully treated with Mohs micrographic surgery have been appearing in the literature. The DFSP literature is reviewed here, including worldwide experience reported to date in the use of Mohs surgery to excise DFSPs. Using this margin control technique, the recurrence rate is shown to be 2.4%, much lower than the best previously reported recurrence rate of 11% when wide local excision was used. Three-dimensional reconstructions of DFSPs, based on Mohs micrographic surgical technique, are also presented. These illustrations provide new insight into the growth characteristics of these tumors and why Mohs micrographic surgery is emerging as the treatment of choice for DFSP.

Adult↗
PubMed1996

Failure to detect connexin43 mutations in 38 cases of sporadic and familial heterotaxy.

BACKGROUND: Heterotaxy results from failure to establish normal left/right asymmetry during embryonic development. Typical manifestations include complex heart defects and malpositioning of abdominal organs. Missense base substitutions clustered in a 150-base pair region of the gap-junction gene connexin43 (cx43) have been implicated in the pathogenesis of heterotaxy. METHODS AND RESULTS: cx43 was studied in 38 cases of sporadic and familial heterotaxy. A 400-base pair region containing the previously reported mutation sites was amplified and directly sequenced in 19 patients. Nineteen additional patients were tested for restriction fragments predicted by two of the previously reported missense substitutions. No difference from normal control subjects was detected in any of the patients. CONCLUSIONS: Randomly selected cases of heterotaxy are unlikely to be the result of mutations in cx43.

Abdomen↗
PubMed1996

Autosomal dominant transmission of familial laterality defects.

Heterotaxy results from failure to establish normal left-right asymmetry during embryonic development. Most familial cases are thought to be autosomal recessive. We have identified a family in which 4 individuals from 3 generations manifest laterality defects. Twenty-five family members have been examined. Two have complete reversal of normal laterality (situs inversus) while 2 others have asplenia, midline liver, and complex cardiac malformations (situs ambiguus). Two additional obligate gene carriers are anatomically normal (situs solitus). Male-to-male transmission confirms autosomal inheritance. Identification of this family establishes an autosomal dominant form of laterality defect, suggesting that a portion of sporadic cases may be new-mutation dominant or unrecognized familial cases. The finding of all forms of laterality (solitus, ambiguus, and inversus) among obligate disease gene carriers within a single family may be relevant to genetic evaluation and counseling in apparently isolated patients with laterality disturbance.

Chromosome Aberrations↗
PubMed1996

DDAVP reduces bleeding during continued hirudin administration in the rabbit.

Hirudin is a potent thrombin inhibitor derived from the leech Hirudo medicinalis salivary gland which has considerable potential for therapeutic use in thrombotic disease. The major risk attendant its use is hemorrhage. This study investigates the hypothesis that the prohemostatic effects of DDAVP infusion can curtail the hemorrhagic effect induced by ongoing hirudin administration. In a randomized and blinded manner, rabbits were exposed to a 15-min intravenous infusion of DDAVP or saline midway through a continuous two-h intravenous infusion of hirudin. Bleeding time was monitored by full thickness ear punctures performed before, during and after hirudin exposure. Hirudin induced a significant hemorrhagic state, manifest as a 7-10-fold prolongation of the primary bleeding time. DDAVP reduced the mean duration of primary bleeding from 10.8 min to 5.9 min (p = 0.001) as well as the number of sites which bled for longer than 6 or 20 min (46% vs 27%, p = 0.002; and 18% vs 5%, p = 0.002, respectively). Although there was no difference in the incidence of spontaneous rebleeding from these sites (44 vs 36%, p = 0.21), rebleeding did not persist as long in animals that received DDAVP (8 vs 16 min, p = 0.005), and fewer sites rebled for longer than 20 min (8 vs 27%, p = 0.027). Results were essentially the same for two different commercial recombinant hirudin preparations. DDAVP appears to attenuate the bleeding caused by continuous hirudin infusion in rabbits and establishes a foundation for clinical assessment in patients.

Animals↗
PubMed1993

Mapping a gene for familial situs abnormalities to human chromosome Xq24-q27.1.

Ambiguous abdominal situs, asplenia/polysplenia and severe cardiac malformations characterize heterotaxy in humans. These anomalies result from the inability of the developing embryo to establish normal left-right asymmetry. We have studied an interesting family in which the heterotaxy phenotype segregates as an X-linked recessive trait. In order to map the heterotaxy locus (HTX), we have analysed 39 family members using highly-polymorphic microsatellite markers from the X chromosome. One of these markers, DXS994, shows no recombination with the disease locus in 20 informative meioses. Linkage analysis results in a maximum lod score of 6.37. Current genetic and physical mapping data assign the order of loci in Xq24-q27.1 as cen-DXS1001-(DXS994, HTX)-DXS984-tel. These results establish the first mapping assignment of situs abnormalities in humans.

Child↗