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Biomedical subjects

B Quinn

Publications and source records attributed to B Quinn.

At least 73 records · Page 4Linked to original sources
PubMed1994

Children with severe epilepsy: evidence of hippocampal neuron losses and aberrant mossy fiber sprouting during postnatal granule cell migration and differentiation.

Surgically resected hippocampi from children with extrahippocampal seizures and structurally non-atrophic brains were examined to determine the relationship of neuron losses and aberrant mossy fiber (MF) sprouting to the postnatal migration and differentiation of the fascia dentata (FD) granule cells (GC). Percent neuron loss compared to age-matched autopsy controls was determined by quantitative cell densities, and aberrant MF sprouting by neo-Timm histochemistry. Postnatal immature GC migration and differentiation was demonstrated by the transient but GC-specific expression of the immature form of neural cell adhesion molecule (NCAM-H). Results showed that the hippocampi from children with seizures appeared microanatomically intact without focal areas of damage. However, significant neuron losses were found by neuron counts in the fascia dentata (P < 0.01), CA4 (P < 0.01), and CA2 (P < 0.05). Aberrant supragranular inner molecular layer MF sprouting was found in hippocampi of children with seizures, and the MFs showed smaller puncta in specimens resected under 2 years of age (n = 3) compared to the larger puncta in older children (n = 5). Hippocampi from children under 2 years of age also demonstrated NCAM-H positive primitive cells in the infragranular and stratum granulosum of the fascia dentata consistent with the postnatal migration and differentiation of GCs, the parent neurons of the MFs. These results indicate that seizures in the immature but structurally intact human hippocampus are associated with decreased neuron densities and aberrant MF sprouting very early in postnatal development. The data also show that aberrant MF sprouting is found during postnatal migration, differentiation and axogenesis of GCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Axons↗
PubMed1994

Postmortem anatomy from cryosectioned whole human brain.

A system of histologic and digital processing protocols are presented for the acquisition of high-resolution digital imagery from postmortem cryosectioned whole human brain and head for computer-based 3-dimensional (3D) representation and visualization. We designed and evaluated several protocols for optimal preparation of frozen specimens including fixation, decalcification, cryoprotection, freezing and sectioning procedures. High-resolution (1024(2) pixel) serial images were captured directly from the cryoplaned blockface using an integrated color digital camera and fiber optic illumination system mounted over a modified cryomacrotome. Specimens frozen and sectioned with the cranium intact preserved brain spatial relationships and anatomic bony landmarks. Color preservation was superior in unfixed tissue heads were incompatible with decalcification and cryoprotection procedures and section collection from such specimens was complicated by bone fragmentation. Collection of 1024(2) images from whole brain resulted in a spatial resolution of 200 microns/pixel in a 1-3 Gbyte data space. Even higher 3D spatial resolution was possible by primary image capture of selected regions such as hippocampus or brain stem. Discrete registration errors were corrected using image processing strategies such as cross-correlative and other algorithmic approaches. Data sets were amenable to resampling in multiple planes as well as scaling and transpositioning into standard coordinate systems. These methods enable quantitative measurements for comparison between subjects and to published atlas data. These techniques allow visualization and measurement at resolutions far higher than those available through other imaging technologies and provide greatly enhanced contrast for delineation of neuroanatomic structures, pathways, and subregions.

Brain↗
PubMed1994

Hurricane Andrew and a pediatric emergency department.

STUDY OBJECTIVE: To determine the effect of Hurricane Andrew on a pediatric emergency department. DESIGN: A retrospective analysis of ED visits through the use of computerized records and chart review. SETTING: A children's hospital in South Florida. TYPE OF PARTICIPANTS: All patients presenting to the ED during the control week and the two study weeks after the hurricane. MEASUREMENTS: Census, diagnoses, admission rate, and patient geographic origin and age. MAIN RESULTS: During week 1, there was an average daily increase of 40.7% in patient volume (P < .01) and a 3.3% decrease in the admission rate (P < .01). The increased census was due mainly to local patients, rather than those from the most devastated areas. More patients were seen with open wounds, gastroenteritis, and impetigo (all, P < .05); more were more than 18 years old (P < .05). By the second week, both census and admission rate returned to normal; cases of cellulitis (P < .05) and open wounds (P < .001) were increased. Although not statistically significant, a higher percentage of hydrocarbon and/or bleach ingestions was seen for both weeks. CONCLUSION: Following a hurricane, personnel in a pediatric ED can expect to see an increased census, with more diagnoses of open wounds, gastroenteritis, and skin infections. They may also see hydrocarbon and bleach ingestions. Alerting parents to the potential for injury and accidental poisoning in their children after a hurricane may help prevent the reported morbidity.

Adolescent↗
PubMed1994

Repetitive and compulsive behavior in frontal lobe degenerations.

The authors review the relationship of repetitive behaviors to frontal lobe degenerations and report the repetitive and compulsive behaviors, radiologic imaging findings, and neuropathology of 3 patients with dementia secondary to frontal lobe degeneration. These 3 patients and 78% of 46 proven pathologic cases of frontal lobe degeneration described in the literature demonstrate repetitive behaviors ranging from motor stereotypies to complex obsessive-compulsive disorder. This review suggests that combined damage to the frontal lobe, caudate nucleus, and globus pallidus may account for the repetitive behaviors seen in frontal lobe degenerations, idiopathic obsessive-compulsive disorder, and other neuropsychiatric diseases.

Adult↗
PubMed1993

Intersecting polymers in lipid bilayers: cliques, static order parameters and lateral diffusion.

We have modelled a macrolipid polymer composed of lipid molecules (monomers) embedded in a lipid bilayer or monolayer and polymerized via their polar groups. Because of fluctuations perpendicular to the plane of the bilayer, the polar region occupied by the polymer chain possesses sufficient space so that the polymer might exhibit 'self-intersection' if its conformational state is projected onto the plane of the bilayer/monolayer. We represent the plane of the bilayer/monolayer by a triangular lattice. Each site can be occupied by a monomer or be empty (and thus occupied by one of the unpolymerizable lipids which make up the bilayer/monolayer). A macrolipid is represented by a sequence of N monomers connected by N-1 bonds. Bonds may be either short (connecting nearest neighbour monomers) or long (between second neighbour monomers), in accord with the average properties of the spacers between the polymerized lipids. We have carried out computer simulation of this system using the Carmesin-Kremer bond stretching algorithm. Although no two monomers can occupy the same site, bonds may cross each other. We analyzed the dependence of and approximately N2vc and + approximately N2 sigma c, where Nsc and Nmc are the number of bond-crossings in the same macrolipid ('self-crossing') or in two different macrolipids ('mutual-crossing'). For single macrolipids, we confirmed that vc = 3/4 and have found that sigma c approximately 0.52, which we consider supports that sigma c = 1/2. For the dense case with monomer concentration, c = 0.72, we found that vc = 1/2 and that sigma c approximately 0.52 supports that sigma c = 1/2. In the semi-dilute regime (c = 0.2) we found crossover behaviour, although sigma c = 1/2. The total number of bond crossings thus scale like N, independent of concentration. We studied the connectivity of the system by calculating the weight averaged cluster, or 'clique', size. Cliques are defined as being composed of all macrolipids which exhibit at least one crossing bond with one other member of the clique. We found that while the average clique contains about two macrolipids at low concentrations, the clique size approaches the maximum possible value at high concentrations if the macrolipids are sufficiently long. In the latter case a transition appears to occur as the macrolipid length increases. This transition occurs at length = 40 when c = 0.72. These observations should have experimental consequences for the viscoelastic properties of the system.(ABSTRACT TRUNCATED AT 400 WORDS)

Computer Simulation↗
PubMed1993

Primary pineal melanoma: case report.

Primary melanomas of the central nervous system are unusual, and those in the pineal region are exceedingly rare. We present a case of primary pineal melanoma in a 60-year-old man. The lesion was subtotally resected through an infratentorial, supracerebellar approach. The clinical features and the histological findings are discussed. Eight previous case reports are reviewed.

Brain Neoplasms↗
PubMed1992

Differential vulnerability of primate caudate-putamen and striosome-matrix dopamine systems to the neurotoxic effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

The meperidine analogue derivative 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces nigrostriatal fiber damage and severe parkinsonism in humans and animals. MPTP-induced parkinsonism has been proposed as a model of Parkinson disease, but doubts have been raised about whether the patterns of nigrostriatal fiber loss in the two conditions are similar. We report here observations on [3H]mazindol monoamine (principally dopamine) uptake-site binding in the striatum of monkeys (Saimiri sciureus) exposed to low doses of MPTP. We show that this treatment can produce a pattern of nigrostriatal degeneration characteristic of that seen in Parkinson disease, in which there is greater depletion of dopaminergic markers in the putamen than in the caudate nucleus, especially posteriorly. Moreover, within the regions of diminished uptake-site binding in the MPTP-treated monkeys, there is differential preservation of binding in striosomes relative to the surrounding matrix. We suggest that both regional and striosome/matrix patterns of nigrostriatal depletion are key features of MPTP-induced neurodegeneration and that both patterns may provide clues to the mechanisms underlying neurodegeneration in Parkinson disease as well.

Animals↗
PubMed1991

Yersinia enterocolitica O:3: an emerging cause of pediatric gastroenteritis in the United States. The Yersinia enterocolitica Collaborative Study Group.

After an outbreak of Yersinia enterocolitica infections among black children in Atlanta, a seven-hospital study was conducted to determine the importance of this pathogen in other communities with large black populations. Of 4841 stool specimens from patients with gastroenteritis examined between November 1989 and January 1990, Y. enterocolitica, Shigella, Campylobacter, and Salmonella were identified in 38, 49, 60, and 98 specimens, respectively; 34 (92%) of 37 Y. enterocolitica isolates were serotype O:3. Of the 38 patients with yersiniosis, 37 (97%) were children. Illnesses were clustered around the holidays, and 20 (62%) of 32 patients had been exposed to raw pork intestines in the 2 weeks before onset. Exposure was significantly associated with illness in a case-control study of eight patients identified at one hospital (P = .004). Infants less than or equal to 6 months old with yersiniosis were more likely to have immature-to-total neutrophil ratios greater than 0.50 than were infants of comparable age with salmonellosis (P = .02). Infrequently isolated in the past, Y. enterocolitica O:3 is emerging as an important enteric pathogen in this country, particularly among black children.

Adolescent↗
PubMed1991

Cell surfaces and fractal dimensions.

The perimeters of the surface membranes of some different cell types have been digitized from electron micrographs and the data analysed in order to discover whether the perimeter can be described by a fractal dimension, df. Micrographs obtained at various magnifications and subsequently enlarged by different amounts have been used. Values of df ranging from 1.02 to 1.34 were manifested over a scale length of about one order of magnitude. Values of df were independent of the magnification, and were the same for cells of the same type. Possible implications of these results are discussed.

Animals↗
PubMed1990

Co-expression of neuropeptides in the cat's striatum: an immunohistochemical study of substance P, dynorphin B and enkephalin.

The expression of tachykinin-like and opioid-like peptides was studied in medium-sized neurons of the caudate nucleus in tissue from adult cats pretreated with colchicine. Two methods, a serial thin-section peroxidase-antiperoxidase technique and a two-fluorochrome single-section technique, were applied. Quantitative estimates were made mainly with the peroxidase-antiperoxidase method. The numbers of neurons expressing substance P-like, dynorphin B-like, and enkephalin-like immunoreactivity were recorded in regions identified, respectively, as striosomes and extrastriosomal matrix. Striosomes were defined by the presence of clustered substance P-positive and dynorphin B-positive neurons and neuropil. Tests for the co-existence of enkephalin-like peptide and glutamate decarboxylase-like immunoreactivity were also made with the peroxidase-antiperoxidase method. Co-expression of substance P-like and dynorphin B-like immunoreactivities was the rule both in striosomes and in the matrix. In striosomes, substance P-like immunoreactivity was found in 96% of dynorphin B-immunoreactive neurons, and in the matrix 89% of dynorphin B-positive cells contained substance P-like immunoreactivity. Substance P/dynorphin B-positive neurons corresponded to over half (57%) of the neurons in striosomes but only 39% of the neurons in the matrix. Both in the matrix and in striosomes, about two-thirds of all neurons (63% and 65%, respectively) were identified as enkephalin-positive. Among all substance P/dynorphin B-positive medium-sized neurons, 76% also contained enkephalin-like antigen. The enkephalin-positive neurons characterized by triple peptide co-existence (enkephalin/substance P/dynorphin B) represented a mean of 63% of striosomal enkephalin-positive neurons (41% of all striosomal neurons) and 35% of matrical enkephalin-positive neurons (26% of all matrical neurons). Finally, nearly all enkephalin-positive neurons were immunoreactive for glutamate decarboxylase, and therefore probably GABAergic, but only about half the glutamate decarboxylase-positive population was enkephalin-immunoreactive. These findings suggest that neuropeptides from three distinct precursors may be co-localized in single medium-sized neurons in the striatum, and that the differential patterns of co-expression of substance P-like, dynorphin B-like, and enkephalin-like peptides may confer functional specializations upon subpopulations of GABAergic neurons giving rise to the efferent projections of the striatum. The linked expression of substance P-like and dynorphin B-like peptides in single neurons both in striosomes and matrix suggests that some regulatory mechanisms controlling peptide expression apply regardless of compartment.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Subjective, social, and physical availability. I. Their interrelationships.

The alcohol availability literature suggests that physical conditions which restrict alcohol availability reduce rates of alcohol consumption. Smart (1980) argued that the availability construct should be expanded to include subjective and social components. It was hypothesized that people who perceived alcohol to be subjectively and socially available would consume more alcohol than those who did not and that physical availability would only indirectly affect consumption. These hypotheses were examined using data from a telephone survey. In Part I, the interrelationships between physical, subjective, and social availability are described. In Part II (this journal, Vol. 25, No. 9), the relationships between these variables and alcohol consumption are explored.

Adult↗
PubMed1990

Subjective, social, and physical availability. II. Their simultaneous effects on alcohol consumption.

Part I of this (this journal, Vol. 25, No. 8, pp. 889-910) series described the theoretical justification for this research, the methods and measures used, and the interrelationships between indicators of physical, subjective, and social availability. Part II explores the relationships between these variables and alcohol consumption using bivariate analyses and structural equation modeling. As predicted, for these metropolitan residents, physical distance from an outlet only indirectly related to alcohol consumption via its negative relationship to subjective availability. Indicators of both subjective and social availability positively related to alcohol consumption. The implications of these results for future availability research and prevention programming are discussed.

Alcohol Drinking↗