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Biomedical subjects

J Kerwin

Publications and source records attributed to J Kerwin.

14 recordsLinked to original sources
PubMed2005

Anatomical and gene expression mapping of the ventral pallium in a three-dimensional model of developing human brain.

Combining gene expression data with morphological information has revolutionized developmental neuroanatomy in the last decade. Visualization and interpretation of complex images have been crucial to these advances in our understanding of mechanisms underlying early brain development, as most developmental processes are spatially oriented, in topologically invariant patterns that become overtly distorted during brain morphogenesis. It has also become clear that more powerful methodologies are needed to accommodate the increasing volume of data available and the increasingly sophisticated analyses that are required, for example analyzing anatomy and multiple gene expression patterns at individual developmental stages, or identifying and analyzing homologous structures through time and/or between species. Three-dimensional models have long been recognized as a valuable way of providing a visual interpretation and overview of complex morphological data. We have used a recently developed method, optical projection tomography, to generate digital three-dimensional models of early human brain development. These models can be used both as frameworks, onto which normal or experimental gene expression data can be mapped, and as objects, within which topological morphological relationships can be investigated in silico. Gene expression patterns and selected morphological structures or boundaries can then be visualized individually or in different combinations in order to study their respective morphogenetic significance. Here, we review briefly the optical projection tomography method, placing it in the context of other methods used to generate developmental three dimensional models, and show the definition of some CNS anatomical domains within a Carnegie stage 19 human model. We also map the telencephalic EMX1 and PAX6 gene expression patterns to this model, corroborating for the first time the existence of a ventral pallium primordium in the telencephalon of human embryos, a distinct claustroamygdaloid histogenetic area comparable to the recently defined mouse primordium given that name [Puelles L, Kuwana E, Puelles E, Bulfone A, Shimamura K, Keleher J, Smiga S, Rubenstein JLR (2000) Pallial and subpallial derivatives in the embryonic chick and mouse telencephalon, traced by the expression of the genes Dlx-2, Emx-1, Nkx-2.1, Pax-6, and Tbr-1. J Comp Neurol 424:409-438; Puelles L, Martínez S, Martínez-de-la-Torre M, Rubenstein JLR (2004) Gene maps and related histogenetic domains in the forebrain and midbrain. In: The rat nervous system, 3rd ed (Paxinos G, ed), pp 3-25. San Diego: Academic Press].

Brain↗
PubMed2001

Automated external defibrillators and sudden cardiac arrest.

In April 1998, R.R., aged 72 (a man with no prior history of cardiac disease), was leaving his house with two friends to play golf when he suddenly collapsed. One friend initiated CPR, and the other called 911 on his cellular phone. A Chatham police squad arrived within three minutes; the police "first responder" applied a portable automated external defibrillator (AED) to the unresponsive patient. The AED instructed the first responder to push the shock button. Pulse and blood pressure were immediately restored, and the patient was brought to the Overlook Hospital Emergency Room. The patient subsequently awakened, had a cardiac catheterization revealing severe three-vessel coronary artery disease, and then underwent successful coronary artery bypass surgery. Two and a half years later he remained asymptomatic and was seen in the office of his cardiologist for a routine semiannual exam. Later that same day he was scheduled to play golf with the same two friends who had previously saved his life.

Electric Countershock↗
PubMed1999

The Medicare home health benefit implications of recent payment changes.

The interim payment system (IPS) for Medicare home health services, enacted in the Balanced Budget Act of 1997, was intended to slow the growth of home health expenses until HCFA could design a new prospective system. Instead, the IPS has acted like a per-case payment system without case-mix adjustment. Its impact on agencies, along with other policy pressures, has been first to slow and then to reverse the dramatic expansion of the home health sector. In this paper, we identify the impetus for payment changes in the recent history of the Medicare home health benefit. We then present emerging evidence about the effects of IPS and other recent policies on home health. Finally, we draw several lessons from this experience for the impending prospective payment system.

Budgets↗
PubMed1998

"Don't know" responses in surveys: is what I know what you want to know and do I want you to know it?

Responses to survey questions are assumed to be based on what respondents can actually draw from memory. For example, if respondents report engaging in some behavior a certain number of times, we assume that a substantive answer reflects what they really know. Conversely, when respondents say that they "don't know" (DK) the answer, it is believed that their response reflects a lack of memory relevant to the question. However, survey responding is now understood to be a highly complex process. In this article, we propose a framework to account for the kind of reports made by respondents to a survey. The framework holds that respondent reports are based on three factors: what the respondent actually knows (the person's "cognitive state"); whether the respondent believes that the potential answer meets the requirements of the question (an "adequacy judgement"); and whether the respondent chooses to provide this answer (the person's "communicative intent"). Subsequently, the article examines how relevant findings in the literature support the framework, and then evaluates the assumptions made about cognitive states in light of the results of two experiments. The literature and research presented demonstrate that survey responding can be accounted for by a framework that assumes responding is based on certain key cognitive processes.

Adult↗
PubMed1995

Unsaturated fatty acids are the active molecules of a glucan-synthase-inhibitory fraction isolated from entomophthoralean protoplasts.

A few entomophthoralean species are able to multiply in a protoplast form. The polysaccharide synthases which synthesize the cell wall are inactivated in this form. An inhibitor of one of the key enzymes of wall synthesis, glucan synthase, was isolated from entomophthoralean protoplasts, using silica column chromatography and HPLC. Thin-layer and gas chromatography revealed free fatty acids in the inhibitory fractions. These fatty acids, including long-chain unsaturated fatty acids, were shown to be responsible for the inhibition of glucan synthase. The fatty acids were generated during incubation of a protoplast homogenate for 36 h at 37 degrees C and were shown to be non-competitive and non-specific inhibitors of glucan synthase.

Aspergillus fumigatus↗
PubMed1991

Distribution of nerve growth factor receptor immunoreactivity in the human hippocampus.

Nerve growth factor (NGF) receptor-like immunoreactivity has been demonstrated in the normal adult human hippocampus, using minimally fixed cryostat sections obtained from snap-frozen tissue and incubated with the mouse monoclonal antibody, ME 20.4. The majority of the reactivity was associated with nerve fibre processes and their terminals. Numerous fibres were apparent in the alveus, originating from the fornix, and extending into the stratum oriens and pyramidal layer of the hippocampal formation. A more diffuse particulate reactivity, presumed to be nerve terminal, was observed around the pyramidal neurons and in the stratum radiatum, stratum lacunosum moleculare and also in the dentate fascia. The pattern of hippocampal NGF receptor immunoreactivity was broadly similar to acetylcholinesterase histochemical localization, indicating a principal localization on cholinergic axons innervating this area. Preliminary observations indicate an overall reduction in NGF receptor-immunoreactive axons and terminals in old age and Alzheimer's disease.

Acetylcholinesterase↗
PubMed1991

Topography, extent, and clinical relevance of neurochemical deficits in dementia of Lewy body type, Parkinson's disease, and Alzheimer's disease.

Cholinergic and monoaminergic (dopaminergic and serotonergic) activities have been examined in postmortem brain tissue in senile dementia of Lewy body type, Parkinson's disease, and Alzheimer's disease. Quantitative data suggest that although extrapyramidal symptoms relate to striatal levels of dopamine, cognitive impairment is most closely associated with cholinergic (but not monoaminergic) deficits in temporal and archicortical areas. Hallucinations, which are most frequent in Lewy body dementia, appear to be related to an extensive cholinergic deficit in temporal neocortex and the resulting imbalance between decreased cholinergic and relatively preserved serotonergic activities. Topographic analyses such as these including consideration of quantitative "threshold" effects, may be relevant to the future anatomic focus of neurochemical investigations in dementia and to the development of appropriate experimental models.

Adult↗
PubMed1990

Evidence of a monoaminergic-cholinergic imbalance related to visual hallucinations in Lewy body dementia.

Senile dementia of Lewy body type is characterized clinically by a relatively acute onset of fluctuating memory loss and confusion, frequently accompanied by visual hallucinations. Neurochemical analyses of temporal cortex has revealed a distinction between hallucinating and nonhallucinating patients in both cholinergic and monaminergic transmitter activities. In contrast with the cholinergic enzyme choline acetyltransferase, which was more extensively reduced in hallucinating individuals, serotonergic S2 receptor binding and both dopamine and serotonin metabolites were significantly decreased in nonhallucinating cases. These results suggest that an imbalance between monaminergic and cholinergic transmitters is involved in hallucinogenesis in the human brain.

Acetylcholine↗
PubMed1976

Complications of peritoneal dialysis.

Peritoneal dialysis is an easily available therapeutic procedure. The complications noted in 490 dialyses over a six-year period in a university hospital have been reviewed. Seventeen major and 624 minor complications occurred. Only four deaths could be attributed to the procedure itself. Peritoneal dialysis is an effective procedure but one with a significant incidence of complications, though few of these are associated with mortality or morbidity for the patient. Various safeguards against these are discussed.

Acute Kidney Injury↗