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D Bryan

Publications and source records attributed to D Bryan.

At least 19 recordsLinked to original sources
PubMed2001

Signatures of hippocampal oxidative stress in aged spatial learning-impaired rodents.

Neurons and glia within the hippocampus of aged, spatial learning-impaired Long-Evans rats exhibit uniquely altered gene expression profiles, and we have postulated oxidative stress as the basis for this. To test this hypothesis we quantitated the extent of protein and nucleic acid oxidative damage, evaluated the status of mitochondrial DNA integrity, and examined several signaling entities and molecular indicators frequently associated with oxidative stress and gliosis. Immunoblotting demonstrated elevated heme oxygenase-1 in the aged-impaired hippocampus and immunocytochemistry suggested that heme oxygenase-1 is largely cytosolic and at least partly neuronal in nature. In the aged-impaired group, immunoreactivity to 8-hydroxy-2'-deoxyguanosine, an oxidative nucleic acid adduct, was found to be elevated in the dentate gyrus and in area CA1 of the hippocampal formation. Isolated mitochondrial DNA was found to be significantly damaged in the aged-impaired group. In the aged learning-impaired rats only, proteins in a 65-kDa band were found to contain excessive levels of carbonyl residues. Glial activation was examined by in situ hybridization histochemistry to tumor necrosis factor alpha and by immunocytochemistry with OX-6, which detects activated microglia. White matter in aged brains exhibited a modest up-regulation of tumor necrosis factor alpha mRNA and OX-6 immunoreactivity, but the hippocampal formation expressed tumor necrosis factor alpha mRNA equivalent to young animals and few OX-6-positive microglia. The mRNA for manganese-dependent superoxide dismutase, which is elevated in the aged hippocampus, was found preferentially expressed in neurons. We conclude that aged hippocampal neurons appear to be under oxidative stress and this is more severe in the learning-impaired subjects, suggesting a possible basis for age-induced cognitive decline.

Aging↗
PubMed2000

Differential vulnerability of primary cultured cholinergic neurons to nitric oxide excess.

Many neuronal nitric oxide synthase (nNOS)-expressing brain neurons, including some cholinergic populations, are resistant to disease or to certain forms of excitotoxicity. Vulnerability to NO excess of forebrain (medial septal/diagonal band; MS-ACh) and brainstem (pedunculopontine/laterodorsal tegmental nuclei; BS-ACh) cholinergic neurons was compared in E16-E18 primary rat brain cultures. MS-ACh cells were approximately 300-fold more sensitive to the NO donor S-nitro-N-acetyl-D,L-penicillamine (SNAP) than were BS-ACh cells. Most (69%) MS-ACh cells contained nuclear DNA fragments by 2 h after addition of SNAP, while only 21% BS-ACh cells were TUNEL-positive after NO excess. Depletion of glutathione content did not potentiate the effect of SNAP on MS-ACh cells, but sensitized BS-ACh cells to the NO donor. Caffeic acid, a putative NF-kappa B inhibitor, enhanced the toxicity of SNAP to cholinergic neurons in both preparations. Our experiments show that cholinergic neurons in mixed primary cultures from different brain regions possess biochemical differences with respect to their vulnerability to NO excess.

Acetylcholine↗
PubMed2000

Design, synthesis and binding at cloned muscarinic receptors of N-[5-(1'-substituted-acetoxymethyl)-3-oxadiazolyl] and N-[4-(1'-substituted-acetoxymethyl)-2-dioxolanyl] dialkyl amines.

Few muscarinic antagonists differentiate between the M4 and M2 muscarinic receptors. In a structure activity study, aimed at discovering leads for the development of a M4 muscarinic receptor-selective antagonist, we have synthesized and tested at cloned muscarinic receptors the binding of a group of dioxolane- or oxadiazole-dialkyl amines, and compared them to our compound 1, which contains the furan nucleus. Although none of these agents were particularly potent at M4 receptors (Kd values were typically 30-70 nM), furan derivatives (-)1 and (+)1 were significantly more potent at M4 receptors than at M2 receptors (approximately 3- and 4-fold, respectively). The dioxolane derivatives 12b and 12c were more than 10-fold selective for the M4 versus the M2 receptors, while the dioxolane derivative 12e was 15-fold more potent at M4 receptors than for M2 receptors. However, these agents bound to M3 receptors with potencies like that for the M4 receptor, so they are not M4-selective. The M4/M2 relative selectivities of some of our compounds are similar to the better hexahydrosiladifenidol derivatives, and may provide some important structural clues for the development of potent and selective M4 antagonists.

Amines↗
PubMed2000

Pregnancy outcome and complications in women with spina bifida.

OBJECTIVE: To describe the antenatal complications, mode of delivery and outcome of pregnancy in women with spina bifida. STUDY DESIGN: Case series of women known to have attended the spina bifida clinic at the Royal Children's Hospital. Medical records, postal questionnaire and telephone interview were utilized to collect data on the effect of pregnancy on the health of women and the effect of spina bifida on pregnancy outcome. RESULTS: Of 207 women born between 1945 and 1975, 23 reported having a pregnancy, and 17 who had completed pregnancies agreed to participate. The 17 women had a total of 29 pregnancies, with 23 pregnancies progressing to births. Fourteen of 17 women had antenatal admissions, with wheelchair-dependent women requiring more-frequent and longer admissions. Recurrent urinary infections in pregnancy occurred in women with a prior history of urinary infections; stomal problems occurred but were not serious; mobility was reduced for two women during pregnancy, with full recovery afterwards; and preexisting pressure sores worsened during pregnancy. Vaginal deliveries occurred in one in five pregnancies of women who were wheelchair dependent and in ten of eighteen pregnancies in independently mobile women, including seven of eight pregnancies of independently mobile women without ileal conduits. Cesarean sections were accompanied by postoperative complications in 10 women. CONCLUSION: Women with spina bifida who become pregnant generally have a positive outcome, with relatively low complication rates.

Adult↗
PubMed1999

Expression of superoxide dismutase messenger RNA in adult rat brain cholinergic neurons.

Superoxide dismutase (SOD) protects cells exposed to an excess of the free radical nitric oxide, by preventing the formation of peroxynitrite. Certain central cholinergic neurons express constitutive nitric oxide synthase (nNOS), and presumably they are at risk from peroxynitrite intoxication. Immunocytochemistry for choline acetyltransferase (ChAT) was combined with in situ hybridization histochemistry (ISHH) to examine whether brain cholinergic populations differ with respect to their expression of the messenger RNA molecules (mRNAs) for the manganese-dependent (Mn-SOD) and copper/zinc-dependent superoxide dismutases (Cu /Zn-SOD). The cholinergic neurons located in the reticular formation of the upper brainstem (the laterodorsal tegmental nucleus [LDTN] and the pedunculopontine nucleus [PPN]) were found to express relatively high levels of Mn-SOD mRNA, whereas cholinergic neurons located in the basal forebrain (substantia innominata [SI], diagonal band [DB], medial septum [MS], and the nucleus basalis magnocellularis [nBM]), and the striatal cholinergic interneurons expressed low to intermediate levels of Mn-SOD mRNA. The rank order of median Mn-SOD mRNA density per cholinergic cell was LDTN > PPN > SI > striatum = nBM = DB > MS. This is similar to the rank order of nNOS mRNA densities in the cholinergic cells in these regions (R = 0.9, p < 0.02). The rank order of Cu/Zn-SOD mRNA levels in cholinergic populations (DB > LDTN = PPN =MS > SI = nBM = striatum) was not correlated with nNOS mRNA (R = 0.29, P > 0.05). Thus, for cholinergic neurons, Mn-SOD may be important for protection from NO-related oxidative stress.

Animals↗
PubMed1999

Steroidogenic factor 1-DNA binding: a kinetic analysis using surface plasmon resonance.

Basal expression of the glycoprotein hormone alpha-subunit gene in pituitary gonadotrophs is partially dependent on a gonadotroph specific element (GSE) which binds the nuclear receptor, steroidogenic factor-1 (SF-1). We have used surface plasmon resonance (SPR) to determine the association (kappa ass), dissociation (kappa diss) and affinity (KA) constants of SF-1 binding to immobilized oligonucleotides containing either the GSE consensus motif or a GSE mutant with a 2 bp substitution in the GSE site (GSEMUT). In vitro translated SF-1 protein bound the consensus GSE with a threefold increase in affinity constant (P<0.01) compared with the GSEMUT. This was due primarily to a significant increase (P<0.05) in the kappa ass for SF-1 to the GSE and a slower kappa diss (P<0.05). The binding interaction was specific and could be significantly inhibited (P<0. 001) by either anti-SF-1 antibody or excess non-biotinylated GSE. The addition of 14 bp wild-type flanking sequences significantly reduced the affinity of SF-1 to both the GSE (P<0.05) and the GSEMUT (P<0.01). This was due to a significant (P<0.01) decrease in kappa ass for the wild-type and mutant long oligonucleotides compared with the short GSE. Nuclear extracts from alphaT3-1 gonadotroph cells also bound the GSE and GSEMUT, giving kappa diss values which were two- to threefold slower than those obtained with in vitro translated SF-1. Thus, SPR is a powerful technique for examining kinetic interaction between SF-1 and its binding site, and is able to demonstrate the effects of mutations and flanking sequences on that interaction.

Base Sequence↗
PubMed1998

Young people with spina bifida: transfer from paediatric to adult health care.

An expectation of health care for young people with disability is that quality coordinated care continues to be available as they pass from the paediatric to the adult health care system. While individual clinicians provide this service well, the widespread absence of coordinated multidisciplinary care for young people with spina bifida in the adult health care system is a major deficiency. This paper describes the planning and implementation that underpinned the transfer of 10 young people with spina bifida from a paediatric to an adult service. The range of structural, financial and 'cultural' barriers that need to be overcome before patients can be successfully transferred is highlighted; lessons learned from this model may serve to facilitate the development of other transfer services.

Adolescent↗
PubMed1998

Osteocalcin production in primary osteoblast cultures derived from normal and Hyp mice.

Rickets and osteomalacia are characteristic features of the Hyp mouse model of human X-linked hypophosphatemia. Hyp mice demonstrate elevated circulating osteocalcin levels, as well as altered regulation of osteocalcin by 1,25(OH)2D3. Whether this osteocalcin abnormality is intrinsic to the osteoblast, or mediated by the in vivo milieu, has not been established. We therefore characterized osteocalcin production and its regulation by 1,25(OH)2D3 in primary cultures of murine osteoblasts and examined osteocalcin and its messenger RNA in response to 1,25(OH)2D3 in cultures of Hyp mouse-derived osteoblasts. Cell viability and osteocalcin production are optimal when murine cells are harvested within 36 h of age. Murine primary osteoblast cultures mineralize and produce osteocalcin in a maturation-dependent fashion (as demonstrated in other species), and continuous exposure to 1,25(OH)2D3, beginning at day 9 of culture, inhibits osteoblast differentiation and osteocalcin production and prevents mineralization of the culture. However, in contrast to other species, exposure to 1,25(OH)2D3, added later (days 17-25) in culture, does not stimulate osteocalcin but arrests osteocalcin production at current levels. Ambient media levels of osteocalcin were no different in cultures from Hyp mice and their normal litter mates, and the down-regulatory response to 1,25(OH)2D3 was comparable in cultures from normal and Hyp mice. Furthermore, expression of osteocalcin messenger RNA in murine cultures is reduced with exposure to 1,25(OH)2D3, and there is no difference between normal and Hyp cultures in this response. Thus, primary murine osteoblasts manifest a species-specific effect of 1,25(OH)2D3 on osteocalcin production. Furthermore, the increased serum osteocalcin production seen in intact Hyp mice, and the altered response to 1,25(OH)2D3 in Hyp mice, are not observed in osteoblast cultures derived from the mutant strain. These data indicate that abnormalities of osteocalcin described in intact Hyp mice require factors other than those present in cultured cells.

Animals↗
PubMed1997

mRNA for the m4 muscarinic receptor subtype is expressed in adult rat brain cholinergic neurons.

A number of pharmacological, anatomical, and immunological studies have previously addressed the subtype identity of the hippocampal muscarinic pre-synaptic autoreceptor. A preponderance of findings indicate that it is of the M2 pharmacological type. Both the m2 and m4 molecular subtypes exhibit M2 pharmacology and there are few drugs that differentiate between these receptors. Pharmacological attempts at defining the hippocampal autoreceptor have yielded conflicting results. The basal forebrain is relatively enriched in m2 muscarinic receptor mRNA and protein, and lesions that denervate the hippocampus of its basal forebrain cholinergic input have shown a decrement in m2, but not m4, receptor protein in the hippocampus. Thus, the anatomical data obtained to date tend to support the view that the m2 subtype is expressed as the hippocampal autoreceptor. We have combined in situ hybridization histochemistry (ISHH) with immunocytochemistry to choline acetyltransferase to examine whether mRNA for the m4 subtype of muscarinic receptor is expressed in central cholinergic neurons. The m4 muscarinic mRNA was found at moderate levels in all subdivisions of the cholinergic basal forebrain, including the medial septum/diagonal band complex (MS/DB). The m4 mRNA was also found in striatal cholinergic interneurons, in the cholinergic reticular core of the upper brainstem, and in brainstem cholinergic motor neurons. Muscarinic m4 receptor mRNA was also found in many non-cholinergic cells in the brain. For example, the hippocampal pyramidal neurons, dentate gyrus granule cells, and entorhinal cortical pyramidal neurons express relatively high levels of m4 mRNA, while in the brainstem the dorsal raphe and pontine reticular nuclei express relatively high levels of this mRNA. The finding of m4 mRNA in the MS/DB cholinergic neurons suggests that this receptor protein might be expressed as an autoreceptor in hippocampal cholinergic terminals.

Animals↗
PubMed1997

Partnership in chronic health care: care management as an integral part of the paediatric hospital system.

Care management for children with complex care needs in the hospital setting is not just about care managers developing and maintaining partnerships between hospital and community professionals, children and their families. It also requires organizational commitment to a system which is patient centred, recognizes parental expertise and offers clinical skills which are co-ordinated across specialty areas.

Australia↗
PubMed1997

Predictors and indicators of academic outcome in children 2 years following traumatic brain injury.

Within the context of a longitudinal study investigating outcome for children following traumatic brain injury, this paper reports on the utility of neuropsychological testing in predicting academic outcome in children 2 years following traumatic brain injury (TBI). Twenty-nine school-age children who were admitted to hospital after TBI were assessed with a battery of neuropsychological and academic measures at 3 and 24 months postinjury. The neuropsychological battery included measures of memory, learning, and speed of information processing. Academic outcome was assessed in terms of post-TBI change in school placement. According to logistic regression analysis, change in placement from regular to special education at 2 years post-TBI was predicted by injury severity and by neuropsychological performance at 3 months post-TBI. Findings suggest that neuropsychological testing is useful in identifying children with special educational needs subsequent to TBI.

Adolescent↗
PubMed1995

Neuropsychological deficit and academic performance in children and adolescents following traumatic brain injury.

Evaluated the utility of neuropsychological testing in predicting academic outcome in children 1 year following traumatic brain injury (TBI). Fifty-one school age children who were admitted to hospital after TBI were assessed with a battery of neuropsychological measures at 3 months postinjury. Academic achievement was assessed at 3 and 12 months postinjury. The neuropsychological battery included intelligence testing and measures of memory, learning, and speed of information processing. Academic outcome was assessed in terms of post-TBI changes in reading, spelling, and arithmetic; changes in teacher ratings of school performance; and change in school placement. According to logistic regression analysis, change in placement from regular to special education at 1-year post-TBI was predicted by injury severity and by neuropsychological performance at 3 months post-TBI. Findings suggest that neuropsychological testing is useful in identifying children with special educational needs subsequent to TBI.

Achievement↗
PubMed1995

Dysphagia: diagnosis and treatment in Kentucky.

Dysphagia, a disorder of swallowing, is commonly associated with neurological and neuromuscular disorders. Damage to the sensation or muscles of the swallowing mechanism leads to unsafe oral motor or pharyngeal movement patterns, placing a patient at risk for development of aspiration pneumonia. At present, multidisciplinary Dysphagia Teams are being used to improve the diagnosis and treatment of swallowing disorders. A survey including all 112 hospitals in the Commonwealth of Kentucky indicates 33 (29%) presently have such a team, while 42 (38%) offer outpatient dysphagia services. In addition, 56 (50%) of the hospitals indicate they perform modified barium swallows which is an essential test for diagnosing and treating dysphagia. An example of how a Dysphagia Team works in one Kentucky rehabilitation hospital is presented to illustrate how to provide early diagnosis and treatment of these problems.

Barium Sulfate↗
PubMed1995

Oral keratinocytes immortalized with the early region of human papillomavirus type 16 show elevated expression of interleukin 6, which acts as an autocrine growth factor for the derived T103C cell line.

Interleukin 6 (IL-6) is a pleiotropic cytokine produced by cells in response to injurious stimuli including viral infections and UV light. Numerous human keratinocyte-derived lines overexpress IL-6 and have been shown to respond to IL-6 as a mitogen. In a survey of such lines, we discovered that two lines, SiHa and Caski, which harbor human papillomavirus (HPV) type 16 genomes, showed the highest levels of secretion. We have, therefore, asked whether immortalization of human keratinocytes with HPV 16 could result in elevated secretion of IL-6. Oral keratinocytes were transfected with a plasmid expressing the entire HPV type 16 early region under the control of the Moloney leukemia virus long terminal repeat promoter. Three immortal lines were derived and tested for their ability to secrete biologically active IL-6. These lines showed 2-, 3-, and 9-fold increases in detectable IL-6 when compared with parental strains of keratinocytes. Cells from one of these lines, T103C, showed a negative growth response to IL-6-neutralizing antisera, suggesting that the secreted IL-6 acted as an autocrine growth stimulator.

Antibodies, Monoclonal↗
PubMed1989

Evaluation of occult cardiac injuries using subxiphoid pericardial window.

During 1987, we performed diagnostic subxiphoid pericardial windows on all stable patients with juxta-cardiac penetrating injuries. This excluded any patient with clinically diagnosed tamponade or shock. Fifty-one patients underwent subxiphoid diagnostic pericardiotomy for suspected cardiac injuries. Forty patients were normotensive on presentation and 11 experienced transient hypotension. All patients were easily resuscitated in the Emergency Department. The time from admission to operation ranged from 20 minutes to 6 hours (average, 2.5 hours). Twelve patients (23.5%) had hemopericardium at the time of subxiphoid diagnostic pericardiotomy (SDP), and cardiac injury was confirmed at sternotomy in all. Two patients (16%) in the positive group were admitted with systolic blood pressures less than 100 mm Hg compared to nine (23%) in the negative group. One patient had a systolic to diastolic pressure gradient less than 30. Central venous pressures in this group of patients ranged from 8 to 23 cm H2O. Nine patients who had pericardial window solely on the basis of location of the injury had positive findings. All nine patients were normotensive on admission, had CVP's less than 12, and had no other overt clinical signs of injury. This represents an overall occult injury rate of 17.6%. At sternotomy, there were eight ventricular, two pulmonary artery, one aortic root, and one atrial injury, all repaired. Two patients in this group had associated abdominal injuries as did 11 in the negative group, all of whom required operation, and may have explained the hypotension in negative patients. There were no complications of SDP and all negative patients were discharged on the second hospital day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗