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Biomedical subjects

D Kennedy

Publications and source records attributed to D Kennedy.

At least 73 records · Page 4Linked to original sources

Behavior and neurocognitive performance in children aged 5-10 years who snore compared to controls.

Sleep disordered breathing in children is a common but largely underdiagnosed problem. It ranges in severity from primary snoring to obstructive sleep apnea syndrome (OSAS). Preliminary evidence suggests that children with severe OSAS show reduced neurocognitive performance, however, less is known about children who snore but do not have severe upper airway obstruction. Participants included 16 children referred to the Ear, Nose and Throat/Respiratory departments of a Children's Hospital for evaluation of snoring and 16 non-snoring controls aged 5-10 years. Overnight polysomnography (PSG) was carried out in 13 children who snored and 13 controls. The PSG confirmed the presence of primary snoring in seven and very mild OSAS (as evidenced by chest wall paradox) in eight children referred for snoring while controls showed a normal sleep pattern. To test for group differences in neurocognitive functioning and behavior, children underwent one day of testing during which measures of intelligence, memory, attention, social competency, and problematic behavior were collected. Compared to controls, children who snored showed significantly impaired attention and, although within the normal range, lower memory and intelligence scores. No significant group differences were observed for social competency and problematic behavior. These findings suggest that neurocognitive performance is reduced in children who snore but are otherwise healthy and who do not have severe OSAS. They further imply that the impact of mild sleep disordered breathing on daytime functioning may be more significant than previously realized with subsequent implications for successful academic and developmental progress.

Analysis of Variance↗

Apparently unstable normal FMR1 alleles in nine developmentally delayed patients: implications for molecular diagnosis of the fragile X syndrome.

The Fragile X syndrome is a common form of X-linked mental retardation, affecting approximately 1 in 4,000 males. Since the discovery of the FMR1 gene responsible for the syndrome, molecular, rather than cytogenetic, diagnosis of Fragile X syndrome has become the gold standard. Numerous molecular diagnostic centers worldwide use PCR and Southern blotting to characterize the size of the CGG repeats within the gene, expansion of which has been shown to be associated with the vast majority of cases of Fragile X syndrome. Instability of this repeat through successive generations has been demonstrated in many patients and has been associated with numerous factors, including repeat length and molecular structure of the repeat. Nine males with normal-size alleles that exhibit repeat length instability by the presence of a second normal length distinct band by repeated PCR analysis from peripheral lymphocytes are reported. Many hypotheses addressing the reason for this apparent instability were tested without elucidating the underlying molecular causes, including cytogenetic analysis, sequence analysis of the repeat locus, and analysis of flanking dinucleotide repeat loci. All patients exhibited a normal complement of sex chromosomes by cytogenetic and molecular analysis. These results from the widely used PCR analysis illustrate an interesting molecular phenomenon and raise many questions relating to the factors and mechanisms involved in trinucleotide instability as well as having implications for the diagnostic testing of the Fragile X syndrome.

Alleles↗

A rapid and sensitive reporter gene that uses green fluorescent protein expression to detect chemicals with estrogenic activity.

A reporter gene sequence was constructed within a eukaryotic expression vector. The altered plasmid contained 2 sequential estrogen response elements (ERE) coupled to a human phosphoglycerate kinase (PGK) promoter inserted upstream from a cDNA sequence encoding enhanced green fluorescent protein (GFP) with a 3'-polyadenylation signal. The plasmid was linearized and transfected into MCF-7 cells, a human breast cancer-derived line that expresses the estrogen receptor (ER). No selectable marker was present in the plasmid, requiring stably transfected cells to be selected by fluorescence-activated cell sorting based on GFP expression after the cells were treated with 10(-9) M 17beta-estradiol (E2). Stably transfected MCF-7 cells (MCF7-ERE) exhibited 2000-3000 times more fluorescence at 488 nm excitation and 512 nm emission than non-transfected cells. MCF7-ERE cells exhibited a linear increase in GFP expression induced over a range of 10(-12) M E2, a concentration giving 2 times the background expression, to maximal expression at 3 x 0(-10) M E2. From the maximal level, GFP expression plateaued, and then declined when E2 was increased to the highest concentration tested, 10(-7) M. 4-Hydroxytamoxifen (TFN-OH) treatment of cells produced a dose-dependent inhibition of E2-induced GFP expression, indicating the interaction of ER in the regulation of GFP gene expression. A series of estrogenic chemicals were evaluated for their capacity to induce GFP expression in MCF7-ERE cells, showing induced expression of GFP at concentrations 2-4 log units higher than the E2 concentration giving maximal GFP expression. The ERE-PGK-GFP reporter gene system is capable of rapid GFP expression in the presence of low concentrations of E2, and of quantifying estrogenicity of chemicals compared with a standard curve of the natural ligand, 17beta-estradiol.

Cell Division↗

The effect of short-term treatment with micronized estradiol on bone turnover and gonadotrophins in older men.

Evidence for the role of estrogen in male bone metabolism has been confirmed by studies on a man with a genetic defect in the estrogen receptor as well as men with aromatase defects. All exhibited tall stature, delayed epiphysial closure, decreased bone density and increased bone turnover. Estrogen is likely to affect bone turnover in men throughout life; therefore, we hypothesized that older men would show decreased bone resorption in response to estrogen therapy. To test our hypothesis, fourteen community-dwelling men with osteopenia of the femoral neck were treated for 9 weeks with micronized estradiol, 1 mg/d, a dose which is effective in postmenopausal women. Each subject served as his own control. Markers of bone resorption, N-terminal collagen crosslinks (NTX) and C-terminal collagen crosslinks (CTX) and markers of bone formation, osteocalcin (OC) and bone specific alkaline phosphatase (BSAP) were measured every 3 weeks during a 9-week treatment period and 9 weeks post-treatment. Sex hormones, gonadotrophins and calciotropic hormones were measured at baseline, 9 weeks on treatment and 9 weeks post- treatment. After 9 weeks of treatment, estradiol and estrone levels increased significantly by greater than 6-fold and 15-fold, respectively. SHBG levels increased significantly by 17%. Testosterone and free testosterone levels decreased significantly by 27% and 34%, respectively. Markers of bone resorption showed wide variation at baseline and while on treatment. There was no correlation between changes in bone markers and changes in estrogen levels. During treatment, 11 patients showed a decrease of NTX or CTX, but three showed an increase. These three and one other subject had high initial levels of FSH and LH, suggesting some degree of primary gonadal failure, which decreased during estrogen therapy. Thus, the change in NTX (and CTX) after 9 weeks of E2 treatment was correlated with initial FSH (r= -.66, p= .01) and LH (r= -.73, p= .003) values. In addition, the largest decrease in free testosterone at 9 weeks was correlated with the higher values for NTX, CTX and BAP (r=-0.66, -0.68, -0.70 respectively; p< or =.01 for each of the markers). Treatment was generally well tolerated. Side effects of treatment were minimal, and included breast tenderness and decreased libido which reversed after treatment. We conclude that it is feasible to give low dose estrogen to healthy older men, but that the effects on bone turnover are not consistent. Changes in central feedback and in endogenous sex hormone production may alter the response of bone turnover to exogenous estrogen in this population.

Aged↗

Thalamic and amygdala-hippocampal volume reductions in first-degree relatives of patients with schizophrenia: an MRI-based morphometric analysis.

BACKGROUND: Schizophrenia is characterized by subcortical and cortical brain abnormalities. Evidence indicates that some nonpsychotic relatives of schizophrenic patients manifest biobehavioral abnormalities, including brain abnormalities. The goal of this study was to determine whether amygdala-hippocampal and thalamic abnormalities are present in relatives of schizophrenic patients. METHODS: Subjects were 28 nonpsychotic, and nonschizotypal, first-degree adult relatives of schizophrenics and 26 normal control subjects. Sixty contiguous 3 mm coronal, T1-weighted 3D magnetic resonance images of the brain were acquired on a 1.5 Tesla magnet. Cortical and subcortical gray and white matter and cerebrospinal fluid (CSF) were segmented using a semi-automated intensity contour mapping algorithm. Analyses of covariance of the volumes of brain regions, controlling for expected intellectual (i.e., reading) ability and diagnosis, were used to compare groups. RESULTS: The main findings were that relatives had significant volume reductions bilaterally in the amygdala-hippocampal region and thalamus compared to control subjects. Marginal differences were noted in the pallidum, putamen, cerebellum, and third and fourth ventricles. CONCLUSIONS: Results support the hypothesis that core components of the vulnerability to schizophrenia include structural abnormalities in the thalamus and amygdala-hippocampus. These findings require further work to determine if the abnormalities are an expression of the genetic liability to schizophrenia.

Adult↗

Retinoic acid-dependent upregulation of mouse folate receptor-alpha expression in embryonic stem cells, and conservation of alternative splicing patterns.

The action of retinoic acid (RA) in normal development and differentiation is mediated by changes in the expression of RA-responsive target genes. We used differential display reverse transcriptase polymerase chain reaction (RT-PCR) to identify RA-responsive genes expressed in embryonic stem (ES) cells and found that murine folate receptor-alpha (FR-alpha) expression is rapidly induced by RA treatment. The observed increase in FR-alpha expression occurs within 3h, is independent of protein synthesis and does not occur when ES cells are differentiated by removal of leukaemia inhibitory factor (LIF), evidence that the response to RA is both direct and specific. Two messenger RNA (mRNA) isoforms of FR-alpha featuring novel sequence in the 5' untranslated region (UTR) were cloned, and both were found to be upregulated by RA. Other splice variants in both the 5' UTR and 3' UTR of FR-alpha mRNA were also identified. There is a striking similarity between these splicing patterns and those reported for human FR-alpha, which also generates multiple isoforms by alternative splicing in the 5' and 3' UTR. The conservation of these splicing patterns in the non-coding regions of the FR-alpha gene between mouse and human suggests that these regions, and in particular the 5' UTR, play an important role in regulating expression of this gene.

3' Untranslated Regions↗

Non-ionic bulky Gd(III) DTPA-bisamide complexes as potential contrast agents for magnetic resonance imaging.

A series of new diethylene triamine pentaacetic acid (DTPA)-bisamide chelates containing bulky alkyl and aryl side chains have been prepared and characterized. Nuclear magnetic relaxation dispersion profiles were measured for the neutral gadolinium [Gd(III)] DTPA-bisamide complexes in water solution, and their chemical exchange times (tau(m)) were found to be in the range of 1.4 to 4.9 micros. Significant enhancements of solvent proton relaxation rates were observed between 10 and 50 MHz for one of the complexes of the series [Gd(III)-DTPA-bis-2-ethylhexylamide] in human serum albumin (HSA) solution, indicating the formation of a paramagnetic macromolecular adduct. The binding association constant K(A) of the complex and the albumin 5.7 x 10(3) M(-1) was obtained, and the relaxivity of the fully bound adduct was determined to be 13.8 mM(-1) s(-1) at 20 MHz and 25 degrees C. The high value of K(A) makes the above derivative a good potential blood pool contrast agent at the physiological HSA concentration.

Contrast Media↗

Safe use of valproic acid during pregnancy.

QUESTION: I have an epileptic patient who plans pregnancy. It took us years to control her seizures, and valproic acid seems to be the only way to control them. What is the risk to her fetus? ANSWER: Neural tube defects (NTDs) are the most common of the major anomalies associated with in utero exposure to valproic acid. About 1% to 2% of exposed fetuses suffer adverse effects.

Adult↗

Perception of first- and second-order motion: separable neurological mechanisms?

An unresolved issue in visual motion perception is how distinct are the processes underlying "first-order" and "second-order" motion. The former is defined by spatiotemporal variations of luminance and the latter by spatiotemporal variations in other image attributes, such as contrast or depth. Here we describe two neurological patients with focal unilateral lesions whose contrasting perceptual deficits on psychophysical tasks of "first-order" and "second-order" motion are related to the maps of the human brain established by functional neuroimaging and gross anatomical features. We used a relatively fine-grained neocortical parcellation method applied to high-resolution MRI scans of the patients' brains to illustrate a subtle, yet highly specific dissociation in the visual motion system in humans. Our results suggest that the two motion systems are mediated by regionally separate mechanisms from an early stage of cortical processing.

Adult↗

Effective in vivo depletion of T cell subpopulations and loss of memory cells in cattle using mouse monoclonal antibodies.

Conditions were established to obtain depletion of T lymphocyte subsets in lymphoid tissues of calves by injection of mouse monoclonal antibodies to T cell antigens. Adverse reactions were avoided by injecting small quantities of antibody, until target cells had disappeared from blood. Two different mechanisms appeared to be responsible for elimination of the target cells. Rapid depletion of T cells was associated with complement-binding antibody isotypes (IgG2a, IgM), suggesting a complement-mediated mechanism. Clearance of T cells after several days was observed with a non complement-binding isotype (IgG1), suggesting phagocytosis or induction of apoptosis as possible mechanisms. Clearance of the cells in peripheral blood and spleen was obtained with 10-20 mg of anti-CD4 or anti-CD8, but almost ten times as much was needed to obtain depletion of the cells in lymph nodes and Peyer's patches. Depletion lasted for 12 days for CD4 T cells and 3 weeks for CD8 T cells. Successful and lasting depletion (at least 2 weeks) was also obtained with other T cell reagents, such as anti-CD2 and anti-WC1 (gamma/delta T cells). Although B lymphocytes could be removed by a complement-binding antibody, complete depletion of these cells only lasted for a few hours, probably because B cells regenerate faster than T cells. T cell function was severely inhibited when CD4+ T cells were depleted. Stimulation of T cells with foot and mouth disease viral antigen (FMDV) in vaccinated calves was non-existent after depletion. Even 2 months after restoration of normal CD4 T cell levels in blood, activity to FMDV was low. This suggested that the depleted T cells were replaced by naive cells.

Animals↗

Prenatally diagnosed neural tube defects: ultrasound, chromosome, and autopsy or postnatal findings in 212 cases.

From January 1990 until December 1996, 212 cases of neural tube defect (NTD) were seen through the Prenatal Diagnosis Program of the University of Toronto. Of the 212 cases, 200 were karyotyped successfully and of these, 13 (6.5%) had chromosome abnormalities. When classified according to the site of the NTD, 2.3% (2/88) of anencephalics, 7.1% (1/14) of encephaloceles, and 10.2% (10/98) of meningomyeloceles had abnormal karyotypes. The absence of associated ultrasound abnormalities was not necessarily predictive of a chromosomally normal fetus; 4/167 (2.4%) of fetuses with isolated NTDs had chromosome abnormalities. Conversely, 24/33 (72%) of fetuses with additional findings on ultrasound had normal chromosomes. The diagnosis of a chromosome abnormality associated with NTD has important implications for recurrence risk and prenatal diagnosis, not only for the parents but potentially for other relatives. Based on our finding that 6.5% of prenatally detected NTDs are associated with chromosome abnormalities, we recommend karyotyping of all fetuses and/or newborns with NTD.

Adolescent↗

Identification of an immunodominant IgE epitope of the Parietaria judaica major allergen.

Par j 1.0101 is one of the two major allergens of the Parietaria judaica (Pj) pollen, and its three-dimensional structure was built by three-dimensional structural homology modeling. The resultant model was used to identify putative IgE binding regions. Western blot analysis of gene fragmentation products showed that the 1 to 30 region was capable of binding specific IgE from a pool of sera (n = 30) of patients allergic to Pj pollen. Using the structural model as a guide, deletion and site-directed mutagenesis of the 1 to 30 region was performed, and the amino acids involved in IgE binding were identified. In addition, a synthetic peptide covering the 1 to 30 region was capable of binding human IgE without triggering histamine release from basophils of Pj allergic patients (n = 6) and thus represents a haptenic molecule with potential use as an immunotolerant agent. This epitope is also present on the Par j 2.0101 major allergen representing a common IgE epitope. It is an immunodominant epitope, since it was capable of inhibiting 30% of all specific IgE against the Pj major allergens, and therefore, it might be a candidate for the future development of immunotherapeutics.

Allergens↗

The use of alternative therapies by children with asthma: a brief report.

OBJECTIVE: To identify the nature and prevalence of alternative therapies used by children with asthma attending a children's hospital. METHODOLOGY: Subjects consisted of a consecutive series of 51 children with asthma aged 1-6 years who were attending the Women's and Children's Hospital, South Australia. Parents of the children completed a questionnaire describing the use of alternative therapies by the children. RESULTS: Approximately 55% of children used alternative therapies for asthma management. Therapies used most commonly were massage, relaxation exercises, diet therapy and vitamins. There was no significant difference in the age, asthma severity, length of time since diagnosis or presence of another illness amongst children who did or did not use alternative therapies. CONCLUSIONS: A substantial proportion of children with asthma who attend paediatric clinics use alternative therapies. Paediatricians should be aware of this and be prepared to discuss alternative therapies with parents. This may facilitate more open doctor-patient relationships and better management of children's asthma.

Asthma↗

Cocaine decreases cortical cerebral blood flow but does not obscure regional activation in functional magnetic resonance imaging in human subjects.

The authors used functional magnetic resonance imaging (fMRI) to determine whether acute intravenous (i.v.) cocaine use would change global cerebral blood flow (CBF) or visual stimulation-induced functional activation. They used flow-sensitive alternating inversion recovery (FAIR) scan sequences to measure CBF and blood oxygen level-dependent (BOLD) sensitive T2* scan sequences during visual stimulation to measure neuronal activation before and after cocaine and saline infusions. Cocaine (0.6 mg/kg i.v. over 30 seconds) increased heart rate and mean blood pressure and decreased end tidal carbon dioxide (CO2). All measures returned to baseline by 2 hours, the interinfusion interval, and were unchanged by saline. Flow-sensitive alternating inversion recovery imaging demonstrated that cortical gray matter CBF was unchanged after saline infusion (-2.4 +/- 6.5%) but decreased (-14.1 +/- 8.5%) after cocaine infusion (n = 8, P < 0.01). No decreases were detected in white matter, nor were changes found comparing BOLD signal intensity in cortical gray matter immediately before cocaine infusion with that measured 10 minutes after infusion. Visual stimulation resulted in comparable BOLD signal increases in visual cortex in all conditions (before and after cocaine and saline infusion). Despite a small (14%) but significant decrease in global cortical gray matter CBF after acute cocaine infusion, specific regional increases in BOLD imaging, mediated by neurons, can be measured reliably.

Adult↗

Visual loss in a returning traveller with tick typhus.

Rickettsial diseases are increasingly found world-wide and should be considered in febrile patients returning from abroad. This case report describes the vasculitic complications of a patient returning from the Republic of South Africa with tick typhus.

Adult↗