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Biomedical subjects

J C Harris

Publications and source records attributed to J C Harris.

At least 37 records · Page 2Linked to original sources

Infraocclusion of primary molars in monozygotic twins: report of two cases.

Genetic factors have been implicated in the aetiology of infraocclusion, but only three published reports describe infraocclusion of primary molars in twins. This case report describes the occurrence of infraocclusion in two pairs of twins. The distribution of affected teeth and the severity of infraocclusion were strikingly similar in each pair. The report provides further evidence of a genetic contribution to the aetiology of the condition, and also highlights the need to examine siblings, and especially twins, of children who present with an infraoccluded primary tooth.

Bicuspid↗

Breast cancer: cured or not?

Survival following treatment of breast cancer may be estimated through the recognition of various prognostic factors. The Case Study presented here calls attention to several of these factors. The reliability and relative value of these prognosticators are discussed. Recommendations are offered for the practical application of prognostic information in the determination of expected mortality.

Adult↗

Dopamine transporters are markedly reduced in Lesch-Nyhan disease in vivo.

Dopamine (DA) deficiency has been implicated in Lesch-Nyhan disease (LND), a genetic disorder that is characterized by hyperuricemia, choreoathetosis, dystonia, and compulsive self-injury. To establish that DA deficiency is present in LND, the ligand WIN-35,428, which binds to DA transporters, was used to estimate the density of DA-containing neurons in the caudate and putamen of six patients with classic LND. Comparisons were made with 10 control subjects and 3 patients with Rett syndrome. Three methods were used to quantify the binding of the DA transporter so that its density could be estimated by a single dynamic positron emission tomography study. These approaches included the caudate- or putamen-to-cerebellum ratio of ligand at 80-90 min postinjection, kinetic analysis of the binding potential [Bmax/(Kd x Vd)] using the assumption of equal partition coefficients in the striatum and the cerebellum, and graphical analysis of the binding potential. Depending on the method of analysis, a 50-63% reduction of the binding to DA transporters in the caudate, and a 64-75% reduction in the putamen of the LND patients was observed compared to the normal control group. When LND patients were compared to Rett syndrome patients, similar reductions were found in the caudate (53-61%) and putamen (67-72%) in LND patients. Transporter binding in Rett syndrome patients was not significantly different from the normal controls. Finally, volumetric magnetic resonance imaging studies detected a 30% reduction in the caudate volume of LND patients. To ensure that a reduction in the caudate volume would not confound the results, a rigorous partial volume correction of the caudate time activity curve was performed. This correction resulted in an even greater decrease in the caudate-cerebellar ratio in LND patients when contrasted to controls. To our knowledge, these findings provide the first in vivo documentation of a dopaminergic reduction in LND and illustrate the role of positron emission tomography imaging in investigating neurodevelopmental disorders.

Adolescent↗

Is excessive daytime sleepiness characteristic of Prader-Willi syndrome? The effects of weight change.

OBJECTIVES: To assess nighttime and daytime sleep patterns in patients with Prader-Willi syndrome and to examine the effects of weight change on excessive daytime sleepiness in patients with this disorder. DESIGN: Case series (within-subject design). SETTING: A university sleep disorders center. PATIENTS: Eight patients (5 males and 3 females), ranging in age from 5.5 to 21 years, who met the diagnostic criteria for Prader-Willi syndrome. INTERVENTIONS: Overnight sleep polysomnographic recording and daytime Multiple Sleep Latency Test. Four of the 8 patients were restudied after their weight had changed. MAIN OUTCOME MEASURES: Changes in the sleep disordered breathing rate and Multiple Sleep Latency Test measures. RESULTS: Sleep-disordered breathing occurred in all patients and was principally characterized by obstructive hypoventilation or episodes of apnea that occurred primarily during rapid eye movement sleep. After weight reduction, 3 patients had respiratory values that were within the broad normal range (disordered breathing rate, < 15 breaths per hour). Statistically significant (P < .05) weight loss effects occurred during nonrapid eye movement sleep (decrease with weight loss, F = 6.243). Excessive daytime sleepiness was documented in 6 of 7 patients who completed the Multiple Sleep Latency Test. Excessive daytime sleepiness was not consistently correlated with body weight or any of the nocturnal sleep variables. CONCLUSIONS: A sleep-related breathing disorder occurred during rapid eye movement and nonrapid eye movement sleep and improved with weight change in patients with Prader-Willi syndrome, emphasizing the importance of weight reduction in clinical management. However, excessive daytime sleepiness persisted despite a reduction in sleep-disordered breathing after weight loss, suggesting a primary disturbance of sleep. Our findings provide additional support for the view that primary hypersomnia is a characteristic feature of the Prader-Willi syndrome.

Adolescent↗

Solution structure of a biologically active cyclic LDV peptide analogue containing a type II' beta-turn mimetic.

The solution structure of cyclo-[Gly-Leu-Asp-Val-BTD] (BTD = beta-turn dipeptide) has been determined by two-dimensional 1H-NMR (nuclear magnetic resonance) spectroscopy and systematic conformational searching combined with molecular dynamics studies. The structure contains two hydrogen bonds between the Gly and Val residues, and a type I beta-turn with Leu and Asp at the (i + 1) and (i + 2) positions of the turn. The cyclic compound shows activity in a scintillation proximity assay (SPA) for the inhibition of the interaction between the integrin alpha 4 beta 1 and vascular cell adhesion molecule-1 (VCAM-I). The structure-activity relationship of the LDV sequence is discussed.

Cloning, Molecular↗

T wave lability: a clue for separating the good from the bad, when ugly.

Non-specific T wave abnormalities have challenged both the clinician and the insurance medical director for decades. Distinction between pathologic and physiologic T wave changes often requires costly and time-consuming diagnostic studies. The literature is reviewed on the subject of T wave manipulation by the oral administration of both potassium and glucose, introducing the concept of T wave lability. Based on this concept, a simple technique is suggested which, in many cases, can safely, expeditiously and inexpensively distinguish between organic and functional T wave changes. When employed in the investigation of asymptomatic insurance applicants with unexplained T wave abnormalities but no known cardiovascular or renal disease, this technique appears to be sufficiently reliable to classify the risk posed by non-specific T wave changes without resorting to a sophisticated, lengthy and costly cardiovascular investigation.

Adult↗

Telling the story: narrative in newspaper accounts of a men's collegiate basketball tournament.

The concept of narrative or story is increasingly being used as s theoretical model for informing research dealing with a wide array of sociocultural phenomena, especially those concerned with communication. Narrative is prevalent in mass media accounts of many different kinds of events. The inherent serialized structure of sport is conducive to media coverage in narrative form. This article uses a narrative perspective to examine journalistic accounts of the 1982 Atlantic Coast Conference (ACC) men's basketball tournament. We found that the accounts contain three major components of narrative: theme, plot, and characters. Winning is the central theme, and it contributes to shaping the plot and characters. The plot is simple and straightforward and centers on the question, "Who will win?" The characters are relatively flat and lack robustness--players offer exceptional athletic skills to coaches who strategically blend their talents. A breakdown occurs between the goal of winning and the goal of entertaining spectators, and this highlights the short-term importance of winning and the longer term importance of performing to entertain spectators. The narrative supports capitalistic economic relations, stemming from the central theme of winning and its ties to competitive individualism, teamwork, and consumerism.

Basketball↗

A combined behavioral/pharmacological treatment of sleep-wake schedule disorder in Angelman syndrome.

Angelman syndrome (AS) is a genetic disorder associated with a deletion on chromosome 15. Behavior problems among children with AS include sleep difficulties. Data are presented on the successful treatment of a sleep-wake schedule disorder (SWSD) in a 9-year-old boy with AS. The treatment program included behavioral and pharmacological components. During baseline, the child slept a mean of 1.9 hours per night and 1.3 hours during the day; night sleep was increased to a mean of 8.3 hours and day sleep was reduced to a mean of .08 hours after introduction of the full-treatment program. Medication was discontinued subsequently, and the child slept a mean of 7.8 hours during the night and .07 hours during the day. At 45-day follow-up, night sleep was maintained at 7.1 hours and day sleep remained stable at .29 hours. This is the first known report of an effective treatment of a SWSD in a child with AS.

Behavior Therapy↗

Ontogeny of noradrenergic effects on ultrasonic vocalizations in rat pups.

The ontogeny of noradrenergic effects and the interaction of opioid and noradrenergic systems on vocalizations in rat pups from Day 10 to Day 18 were evaluated. Day 10 pups given clonidine (0.05 or 0.5 mg/kg) ip showed a sustained high level of calling throughout a 25-min isolation period that was reversed with yohimbine (0.1 mg/kg). Day 15 pups showed identical profiles with a lower baseline rate. Day 17 pups' calls were differentially affected according to dose; Day 18 pups reduced vocalizing with clonidine. In addition, it was found that at all ages when clonidine increased calling during isolation, the pups vocalized in the nest as well. Naltrexone, an opioid antagonist, lost its effectiveness to increase vocalizations after Day 15 unless it was given subsequent to clonidine. These results suggest that pups' vocalizations are differentially affected by noradrenergic and opioid stimulation or inhibition with developmental changes.

Aging↗

Experimental animal modeling of depression and anxiety.

Experimental animal models have been introduced to study aspects of psychiatric symptoms of depression and anxiety; however, there is no comprehensive animal model for these conditions. The models introduced may simulate certain symptoms (despair), be used to evaluate behavioral theories (cognitive theory of learned helplessness), allow study of underlying neurochemical mechanisms (CSF metabolites, genetic, neurotransmitter model), be used to evaluate developmental issues, and lead to finding new treatments through preclinical pharmacologic trials. A variety of models are needed, as each one attempts to deal with a particular aspect of a syndrome. Pharmacologic models, the model of uncontrollability, separation models, and genetic approaches have been summarized. Depression is viewed as a complex, multifactorial illness. Anxiety models have focused on pharmacologic treatment of motivational conflict and the elicitation of fear and panic through environmental and drug manipulations. The most recent investigations in this area address separation calls and alarm calls in primates as potential models for separation distress and panic symptomatology, arguing that the behavioral context as well as the specific behavior be considered. Animal models have emphasized adult psychopathology in the past. However, with increased recognition of psychiatric disorders in children and adolescents, animal modeling of disorders that begin in the development period assumes importance. Studies in the animal modeling of depression and anxiety involving genetic models, psychosocial models, and stress-induction models are the focus of continuing investigations and may be pertinent to child and adolescent psychopathology. They offer hope for learning more about the neurobiologic mechanisms involved in these conditions and for testing new treatment approaches.

Animals↗

Combined opiate/adrenergic receptor blockade enhances squirrel monkey vocalization.

This study provides evidence for the interaction between opiate and noradrenergic neuronal systems on primate vocal behavior. The rate of twitters produced by adult squirrel monkeys was increased in an additive or synergistic manner by the combined administration of the alpha 2 adrenergic antagonist yohimbine and the opiate antagonist naloxone. Similar effects were not demonstrated on the isolation call. In addition, the drug combination led to an increase of autonomic symptoms. The anatomical localization of these findings and mechanism for the production of increased twitters requires further investigation.

Adrenergic alpha-Antagonists↗

Mediation of separation distress by alpha 2-adrenergic mechanisms in a non-human primate.

This study provides the first behavioral evidence in support of an alpha-adrenergic mechanism underlying imipramine's amelioration of separation distress. The rate of separation-induced vocalization by adult squirrel monkeys was decreased by imipramine and the alpha 2-adrenergic agonist clonidine, and increased by the alpha 2-adrenergic antagonist yohimbine. Yohimbine, but not the alpha 1-antagonist prazosin, reversed the clonidine effect suggesting that drugs acting directly on alpha 2-receptors may have a role in management of separation anxiety.

Adrenergic alpha-Agonists↗

Positron emission tomographic study of D2 dopamine receptor binding and CSF biogenic amine metabolites in Rett syndrome.

We report on the first positron emission tomographic study of dopamine receptor binding in Rett syndrome. The patient is a 25 year old Austrian woman diagnosed at age 2 and followed since then by Rett. A computed axial tomogram (CT scan) showed cortical atrophy, and enlarged ventricles but normal structure of the caudate/putamen. Following the CT scan 20 mCi of 11 C N-methyl spiperone, a butyrophenone with a high affinity for dopamine D2 receptors was administered intravenously. The patient was found to have dopamine D2 receptor binding activity in the low normal range. The caudate/cerebellar activity ratio was below the mean regression line (p = 0.10) that relates the CA/CB ratio as a function of age. Levels of cerebrospinal fluid neurotransmitter metabolites were normal.

Adult↗