Biomedical subjects

V Hinton

Publications and source records attributed to V Hinton.

8 recordsLinked to original sources

PubMed2004

Aromatic L-amino acid decarboxylase deficiency: clinical features, treatment, and prognosis.

BACKGROUND: Deficiency of aromatic L-amino acid decarboxylase (AADC) is associated with severe developmental delay, oculogyric crises (OGC), and autonomic dysfunction. Treatment with dopamine agonists and MAO inhibitors is beneficial, yet long-term prognosis is unclear. OBJECTIVE: To delineate the clinical and molecular spectrum of AADC deficiency, its management, and long-term follow-up. RESULTS: The authors present six patients with AADC deficiency and review seven cases from the literature. All patients showed reduced catecholamine metabolites and elevation of 3-O-methyldopa in CSF. Residual plasma AADC activity ranged from undetectable to 8% of normal. Mutational spectrum was heterogeneous. All patients presented with hypotonia, hypokinesia, OGC, and signs of autonomic dysfunction since early life. Diurnal fluctuation or improvement of symptoms after sleep were noted in half of the patients. Treatment response was variable. Two groups of patients were detected: Group I (five males) responded to treatment and made developmental progress. Group II (one male, five females) responded poorly to treatment, and often developed drug-induced dyskinesias. CONCLUSIONS: The molecular and clinical spectrum of AADC deficiency is heterogeneous. Two groups, one with predominant male sex and favorable response to treatment, and the other with predominant female sex and poor response to treatment, can be discerned.

Adolescent↗

PubMed1999

Premutation female carriers of fragile X syndrome: a pilot study on brain anatomy and metabolism.

OBJECTIVE: It was thought that premutation carriers of fragile X syndrome (FraX) have no neurobiological abnormalities, but there have been no quantitative studies of brain morphometry and metabolism. Thus the authors investigated brain structure and metabolism in premutation carriers of FraX. METHOD: Eight normal IQ, healthy female permutation FraX carriers aged 39 +/- 9 years (mean +/- SD) and 32 age-sex-handedness-matched controls (39 +/- 10 years) were studied; in vivo brain morphometry was measured using volumetric magnetic resonances imaging, and regional cerebral metabolic rates for glucose were measured using positron emission tomography and (18F)-2-fluoro-2-deoxy-D-glucose. RESULTS: Compared with controls, FraX premutation carriers had a significant (1) decrease in volume of whole brain, and caudate and thalamic nuclei bilaterally; (2) increase in volume of hippocampus and peripheral CSF bilaterally, and third ventricle; (3) relative hypometabolism of right parietal, temporal, and occipital association areas; (4) bilateral relative hypermetabolism of hippocampus; (5) relative hypermetabolism of left cerebellum; and (6) difference in right-left asymmetry of the Wernicke and Broca language areas. CONCLUSIONS: Premutation carriers of FraX, as defined by analysis of peripheral lymphocytes, have abnormalities in brain anatomy and metabolism. The biological basis for this is unknown, but most likely it includes tissue heterogeneity for mutation status. The findings may be of relevance to people counseling families with FraX and to understanding other neuropsychiatric disorders which are associated with expansion of triplet repeats and genetic anticipation.

Adult↗

PubMed1992

Individual, but not simultaneous, glucagon and cholecystokinin infusions inhibit feeding in men.

Pancreatic glucagon and cholecystokinin octapeptide (CCK-8) were intravenously infused (1 ml/min for 10 min) alone or in combination beginning 15 min after normal-weight men had eaten a 500-ml tomato soup preload and 5 min before they were served a lunch of macaroni and beef with tomato sauce. Infusion of approximately 3 ng.kg-1.min-1 glucagon or approximately 2 ng.kg-1.min-1 CCK-8 each reduced test meal size. However, simultaneous infusion of these peptide doses reduced meal size less than the sum of the peptides' individual effects. Infusions of approximately 1.5 ng.kg-1.min-1 glucagon or approximately 1 ng.kg-1.min-1 CCK-8 had neither individual nor interactive effects on meal size. Psychophysical ratings failed to detect nonspecific side effects after any of the infusions. That exogenous glucagon and CCK-8 each reduced meal size without side effects suggests that these peptides may participate in the physiological control of human appetite; that their simultaneous infusion resulted in an infra-additive reduction in meal size suggests that they can interact antagonistically.

Adolescent↗

PubMed1988

Maintenance of intraoral pressure during speech after maxillary resection.

Although structural defects such as cleft palate and severe anterior open bite alter vocal tract resistance, compensatory responses usually result in maintaining consonant pressures at an adequate level. The purpose of the present study was to determine if individuals with an acquired palatal defect spontaneously develop similar compensatory behaviors. The pressure-flow technique was used to measure aerodynamic variables associated with consonant production after surgery and obturation. Although intraoral pressures decreased considerably immediately after surgery, pressures were maintained at a mean level of 3.5-cm H2O. Respiratory volumes increased as much as fourfold without obturation and were normal with obturation. Voice-voiceless differences in air volumes among consonants were maintained even in the presence of the defect. These findings suggest that compensatory responses are directed toward maintaining an appropriate level of intraoral pressure for consonant production.

Adult↗

PubMed1987

Physiologic responses to maxillary resection and subsequent obturation.

Aerodynamic assessment of prosthetic obturation provides the clinician with important information on adequacy of the seal between the oral and nasal cavities. The technique is easy to apply and provides quantitative data on effectiveness of obturation. In addition, the pressure-flow technique provides important information on how individuals respond to changes in the integrity of oral and pharyngeal structures. This study demonstrates that individuals with large surgical defects increase respiratory effort during nonnasal consonant productions in order to maintain adequate intraoral speech pressures. Successful obturation of the defect maintains the speech pressures while dramatically reducing respiratory effort.

Adult↗

PubMed1987

Epinephrine inhibits feeding nonspecifically in the rat.

The hypothesis that epinephrine (EPI) and pancreatic glucagon (PG) inhibit feeding by activating a common physiological satiety mechanism was tested by comparing the two agents' behavioral effects. In several tests of specificity, EPI and PG had functionally different inhibitory actions. Intraperitoneal injection of 6.25-50 micrograms/kg EPI and 100-400 micrograms/kg PG elicited overlapping dose-related inhibitions of intake of milk diet in rats maintained ad lib on pelleted chow. Twenty-five to 50 micrograms/kg EPI also elicited anomalous behaviors that are not normally associated with feeding, including supine postures with limbs extended and crawling with trunk dorsoflexed and abdomen pressed against cage floor. EPI elicited similar anomalous behaviors in rats that either sham fed with open gastric cannulas, drank after water deprivation, or were presented neither food nor water. Fifty to 200 micrograms/kg EPI also inhibited water intake in the thirsty rats, and 25-50 micrograms/kg EPI inhibited sham feeding. PG, in contrast, neither elicited anomalous behaviors nor inhibited water intake nor inhibited sham feeding. These data demonstrate that the inhibitory actions of exogenous EPI and PG are functionally dissociable. We conclude that 25-200 micrograms/kg EPI acts nonspecifically to produce anorexia and adipsia, while PG elicits postprandial satiety.

Animals↗

PubMed1986

Combined injection potentiates the satiety effects of pancreatic glucagon, cholecystokinin, and bombesin.

Pancreatic glucagon (PG), cholecystokinin (CCK), and bombesin (BBS) were injected individually and in combination before nondeprived rats were offered condensed milk test meals. Peptide doses that were individually below the threshold for reliable inhibition of meal size (0.15 microgram/kg CCK, 0.75 microgram/kg BBS, 100 micrograms/kg PG) combined to inhibit meal size 19-40%. The inhibitions produced by combinations including CCK were 16-21% more than the sum of the inhibitions elicited by individual injections. This indicates a potentiation of inhibition. In contrast, when peptide doses were increased, the inhibitory effects of the combinations were similar to the sum of the individual injections. None of the peptide treatments disrupted the normal behavioral sequence of postprandial satiety, and they did not reliably affect water intake in water-deprived rats. We conclude that exogenous CCK, BBS, and PG can interact to potentiate postprandial satiety.

Animals↗

PubMedDate not supplied

Brief screening questionnaire for determining affected state in fragile X syndrome: a consensus recommendation.

New molecular research has provided strong evidence for different forms of the fragile X mutation. These findings suggest the need to develop a more standardized and sensitive method for determining neurobehavioral effects of the fragile X gene(s), particularly for molecular studies of patients who do not have obvious mental retardation. This report describes a brief screening questionnaire designed to increase the detection of neurobehavioral dysfunction in individuals from fragile X families who are included in new molecular studies. Improved detection of the affected state in fragile X syndrome will allow more valid clinical data to be correlated with the important molecular information currently being collected.

Behavior↗