Biomedical subjects

Guojun He

Publications and source records attributed to Guojun He.

5 recordsLinked to original sources

PubMed2007

Intracranial abnormalities detected by three-dimensional magnetic resonance imaging in Prader-Willi syndrome.

The neuropathologic abnormalities associated with Prader-Willi syndrome (PWS) are largely unknown. PWS is due to the loss of several paternally expressed genes in chromosome 15q11-q13 region. Several of the imprinted genes in the 15q11-q13 region are normally expressed in the brain and thought to be necessary for neuronal growth and development. Thus, we hypothesized that we would find abnormalities in gray and white matter growth in individuals with PWS. We evaluated three-dimensional (3-D) MRI scans of 20 individuals with PWS, aged three months to 39 years, and compared them to 3-D MRI scans of 21 normal weight sibling controls and 16 individuals with early-onset morbid obesity (EMO) of unknown etiology. The interpreters of the scans were blinded to the diagnosis of the subjects. Intracranial abnormalities in individuals with PWS included ventriculomegaly (100% of individuals), decreased volume of brain tissue in the parietal-occipital lobe (50%), sylvian fissure polymicrogyria (60%), and incomplete insular closure (65%). None of the EMO or normal weight control subjects had any of these findings. We found multiple morphologic brain abnormalities in subjects with PWS suggesting that the loss of paternally expressed genes in chromosome 15q11-q13 region may result in abnormalities of neuronal development. The specific mechanisms underlying these neuropathological abnormalities and their correlation with the clinical phenotype remain to be elucidated.

Adolescent↗

PubMed2006

Enhanced activation of reward mediating prefrontal regions in response to food stimuli in Prader-Willi syndrome.

BACKGROUND: Individuals with Prader-Willi syndrome (PWS) exhibit severe disturbances in appetite regulation, including delayed meal termination, early return of hunger after a meal, seeking and hoarding food and eating of non-food substances. Brain pathways involved in the control of appetite in humans are thought to include the hypothalamus, frontal cortex (including the orbitofrontal, ventromedial prefrontal, dorsolateral prefrontal and anterior cingulate areas), insula, and limbic and paralimbic areas. We hypothesised that the abnormal appetite in PWS results from aberrant reward processing of food stimuli in these neural pathways. METHODS: We compared functional MRI blood oxygen level dependent (BOLD) responses while viewing pictures of food in eight adults with PWS and eight normal weight adults after ingestion of an oral glucose load. RESULTS: Subjects with PWS demonstrated significantly greater BOLD activation in the ventromedial prefrontal cortex than controls when viewing food pictures. No significant differences were found in serum insulin, glucose or triglyceride levels between the groups at the time of the scan. CONCLUSIONS: Individuals with PWS had an increased BOLD response in the ventromedial prefrontal cortex compared with normal weight controls when viewing pictures of food after an oral glucose load. These findings suggest that an increased reward value for food may underlie the excessive hunger in PWS, and support the significance of the frontal cortex in modulating the response to food in humans. Our findings in the extreme appetite phenotype of PWS support the importance of the neural pathways that guide reward related behaviour in modulating the response to food in humans.

Adult↗

PubMed2005

A full-size MRI-compatible keyboard response system.

Two commercially available plastic keyboards were contrasted in the degree to which they interfered with echo planar imaging. One keyboard (GrandTec USA's "Virtually Indestructible Keyboard") caused significantly less temporally variant and invariant signal loss and was integrated into a MRI interface system for recording participants' manual motor responses. The response recording system is safe, accurately records reaction time behavioral data, and does not interfere with functional data collection. Implementing this MRI-compatible keyboard allows the collection of motor responses from complex manual behaviors (i.e., typing) and thus represents a valuable tool for functional MRI (fMRI) studies.

Adult↗

PubMed2003

A step-wise application of methylprednisolone versus dexamethasone in the treatment of acute exacerbations of COPD.

OBJECTIVE: The aim of the study was to explore the clinical value of a step-wise application of methylprednisolone (MP) compared to dexamethasone (DXM) in acute exacerbations of COPD. METHODOLOGY: One hundred and forty-two patients with an acute exacerbation of COPD were divided randomly into two groups: 71 patients were treated with MP and the other 71 patients were treated with DXM. Otherwise each group was given the same basic treatments: antibiotics, bronchodilators, oxygen therapy as well as standard hospital care. The patients in the MP group were given a tapering dose of MP for 7-14 days, and the patients in the DXM group were given a corresponding tapering dose of DXM for 7-14 days. Then both groups were given a gradually reducing dose of oral prednisone for 2-3 weeks. Two weeks before the prednisone was tapered off, inhaled corticosteroid was introduced. The patients' symptom scores, physical signs, per cent predicted FEV1%, and arterial blood gases were monitored before treatment and after the seventh day of treatment. RESULTS: There was an obvious improvement in symptoms after 1-3 days in all 71 patients in the MP group, with their wheezing being distinctly reduced or disappearing entirely. The maximum benefit that occurred in the MP group (90.14%) was considerably higher than that of the DXM group (25.35%), P < 0.05. The predicted FEV1% in the MP group increased from 46.7 +/- 10.6 to 67.5 +/- 12.4, compared with an increase in the DXM group from 50.1 +/- 7.6 to 58.9 +/- 10.8. The difference between the two groups was significant (P < 0.05). CONCLUSIONS: An adequate and tapering dose of MP used in acute exacerbations of COPD can relieve the inflammatory reaction in airways and reduce airway spasm more promptly than DXM.

Acute Disease↗

PubMed2002

[A clinicopathologic study of nonspecific interstitial pneumonia].

OBJECTIVE: To investigate the clinicopathologic features of nonspecific interstitial pneumonia (NSIP). METHODS: The clinical and pathological data of 8 cases with NSIP confirmed by open or video-assisted thoracoscopic lung biopsy were reviewed retrospectively. RESULTS: NSIP occurred more in female (male:female 1:3, 2/6), and the patients' average age was 48 years. The clinical manifestation was progressive dyspnea, cough and sputum, crackles over both lungs and restrictive ventilating abnormalities. Reticular changes and patchy ground-glass attenuation in lower lung fields were the main findings on high resolution computed tomography. The pathological characteristic was uniform interstitial inflammation and fibrosis. Three cases showed fibroblast foci, was BOOP like changes in 4 and honeycombing in 1 case. of the 8 patients, 6 had cellular and fibrosing patterns; 2 had fibrosing patterns only; the former showed better response to glucocorticoid therapy than the latter. CONCLUSIONS: The histologic patterns of NSIP correlated closely with the therapeutic effect of glucocorticoids. It is difficult to differentiate pathologically the fibrosing pattern of NSIP from usual interstitial pneumonia, therefore clinical data are indispensable in the diagnosis.

Adult↗