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Biomedical subjects

F L Chang

Publications and source records attributed to F L Chang.

At least 19 recordsLinked to original sources
PubMed2003

Effects of different exercise modes on mineralization, structure, and biomechanical properties of growing bone.

Weight bearing during exercise plays an important role in improving the mechanical properties of bone. The effect on bone of non-weight-bearing exercise such as swimming remains controversial. To investigate the effects of exercise mode on growing bone, 29 male Wistar rats (7 wk old) were randomly assigned to a running exercise group (Run, n = 9), a swimming exercise group (Swim, n = 10), or a nonexercise control group (Con, n = 10). During an 8-wk training session (20-60 min/day, 5 days/wk), the Run rats were trained at progressively increasing running speeds (12-22 m/min), and weights attached to the tail of the Swim rats were progressively increased from 0 to 2% of their body weight. The bone mineral density of the proximal tibiae of the Run rats was significantly higher than in the Swim (P < 0.05). Femoral wet weights of the two exercise groups were significantly higher than in the control group (P < 0.05). Interestingly, the percent difference between the tissue wet weight and dry weight (water content ratio), which is related to bone mechanical properties, was significantly higher in the tibiae of the Swim rats and the femora of both exercise groups compared with controls (P < 0.05). Extrinsic as well as intrinsic biomechanical material properties were measured in a three-point bending test. Bone mechanical properties of the tibiae and femora of rats in the Swim and Run groups were significantly greater than those in the control group (P < 0.05). In summary, different modes of exercise may benefit bone mechanical properties in different ways. The specific effects of swimming exercise (non-weight-bearing exercise) on bone require further study.

Algorithms↗
PubMed2003

The feasibility study of the octane-enhancing process: isobutylene dimerization using C4 mixture.

The dimerization of isobutylene to diisobutylene in C4 mixture was evaluated using various catalysts such as nickel salts system, zeolite system and acidic ion exchange resin. There were shown that the strong acidic type ion exchange resin (Amberlyst 15) under 6 kg/cm2 and 60 degrees C gave rise to 90% conversion and more than 60% selectivity to diisobutylene with acceptable amounts of oligomer as a best catalyst. Therefore, Amberlyst 15 was employed to investigate the optimum reaction condition. In the batch reaction, since the catalyst activity was increased with the increasing reaction temperature, the reaction time should be shortened appropriately to prevent a high yield of oligomer. The reaction rate was increased by the increased amount of catalyst without much change in the product composition. The formation of oligomer was inhibited when a small amount of organic solvents (methyl tert-butyl ether) are attended. In the fixed-bed study, the results indicate that the increase in reaction temperature was accompanied by the increase in reaction rate, however, the selectivity to the dimer was affected. Higher WHSV will enhance the selectivity but reduce the conversion. Conclusively, the appropriate reaction condition was 45 degrees C with WHSV of 10.

Air Pollution↗
PubMed2001

Various forms of mutant p53 confer sensitivity to cisplatin and doxorubicin in bladder cancer cells.

PURPOSES: The nature of p53 mutation has been reported to affect cellular responses to chemotherapy. We characterized the impact of p53 mutations on drug resistance in bladder cancer cells. METHODS AND METHODS: Various human p53 mutants (V143A, V173L, H179Q, N247I and R273H) were introduced to the TCC-SUP bladder carcinoma cell line to establish stable transfectants. The expression of mutant p53 was demonstrated by reverse transcriptase-polymerase chain reaction and immunocytochemical analysis. The sensitivity to cisplatin and doxorubicin in these transfectants was determined by trypan blue exclusion. Cell death mediated by cisplatin and doxorubicin was characterized by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling analysis, Hoechst 33258 staining and annexin-V binding assay. RESULTS: The expression of all forms of mutant p53 protein except p53His273 enhanced sensitivity to cisplatin and doxorubicin. The chemosensitivity of p53His273 transfectants is similar to that of parental TCC-SUP and control transfectants. Cisplatin induced cell death undergoes apoptosis, as demonstrated by Hoechst staining, annexin-V assay and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling, respectively. In contrast, doxorubicin induced cell death probably occurs through a nonapoptotic pathway. CONCLUSIONS: These results indicated that the nature of p53 mutations may affect the cellular response to anticancer drugs and many forms of mutant p53 protein may enhance chemosensitivity through apoptotic or nonapoptotic pathways in bladder cancer cells.

Cells, Cultured↗
PubMed2000

Clinical criteria for the diagnosis of vascular dementia: a multicenter study of comparability and interrater reliability.

BACKGROUND: Several clinical criteria have been developed to standardize the diagnosis of vascular dementia (VaD). Significant differences in patient classification have been reported, depending on the criteria used. Few studies have examined interrater reliability. OBJECTIVE: To assess the concordance in classification and interrater reliability for the following 4 clinical definitions of VaD: the Hachinski Ischemic Score (HIS), the Alzheimer Disease Diagnostic and Treatment Centers (ADDTC), National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN), and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). METHODS: Structured diagnostic checklists were developed for 4 criteria for VaD, 2 criteria for Alzheimer disease (AD), and 4 criteria for dementia. Twenty-five case vignettes, representing a spectrum of cognitive impairment and subtypes of dementia, were prepared in a standardized clinical format. Concordance in case classification using different criteria and interrater reliability among 7 ADDTCs given a specific set of criteria was assessed using the kappa statistic. RESULTS: The frequency of a diagnosis of VaD was highest using the modified HIS or DSM-IV criteria, intermediate using the original HIS and ADDTC criteria, and lowest using the NINDS-AIREN criteria. Scores for interrater reliability ranged from kappa = 0.30 (ADDTC) to kappa = 0.61 (original HIS). CONCLUSIONS: Clinical criteria for VaD are not interchangeable. Depending on the criteria selected, the reported prevalence of VaD will vary significantly. The traditional HIS has higher interrater reliability than the newer criteria for VaD. Prospective longitudinal studies with clinical-pathological correlation are needed to compare validity.

Aged↗
PubMed1999

Postoperative intramuscular dextromethorphan injection provides postoperative pain relief and decreases opioid requirement after hemorrhoidectomy.

BACKGROUND: Previous studies have shown that dextromethorphan (DM) produces an analgesic/antihyperalgesic effect. This study was designed to examine whether postoperative DM intramuscular (i.m.) injection could reduce post-hemorrhoidectomy pain. METHODS: At the end of the surgery, patients in the study group (n = 30) were given an intramuscular injection of 40 mg DM and 20 mg chlorpheniramine (CPM) while in the study group (n = 30), the patients were given intramuscular 20 mg CPM only. Pethidine (1 mg/kg, i.m.) was prescribed for postoperative pain relief if required. The time to first pethidine injection, total pethidine consumption, worst pain score, and pethidine-related side effects were recorded for 48 h postoperatively. RESULTS: The time from the end of operation to the first pethidine injection was 5.4 +/- 1.6 h and 17.8 +/- 3.7 h (P = 0.006) in the control group and the study group, respectively. Total pethidine consumption was 139.5 +/- 11.5 mg and 77.5 +/- 12.2 mg (P < 0.001) in the control group and the study group, respectively. The worst VAS score was 7.5 +/- 0.2 and 7.1 +/- 0.2 (P = 0.09) in the control and the study groups, respectively. The number of patients who required pethidine injection was 29 and 21 (P < 0.005) in the control and the study groups, respectively. The number of patients who suffered pethidine-related side effects was 7 and 1 (P < 0.025) in the control and the study groups, respectively. CONCLUSIONS: We found that intramuscular DM given at the end of operation could provide good postoperative pain relief and decrease the pethidine requirement after hemorrhoidectomy.

Adult↗
PubMed1993

Astrocytic and synaptic response to kindling in hippocampal subfield CA1. I. Synaptogenesis in response to kindling in vitro.

Early morphological events associated with the genesis of epileptiform activity are essentially unknown, despite significant progress on morphological correlates of potentially related plastic neural phenomena. Hippocampal area CA1 shows the capacity to generate epileptiform bursting activity after certain patterns of electrical stimulation. Using an in vitro slice kindling preparation, we found increases in the numbers (areal densities) of shaft and sessile spine synapses in hippocampal subfield CA1 within minutes following the establishment of stable afterdischarges. These data strongly suggest that synaptogenesis is associated with the early stages of epilepsy formation.

Animals↗
PubMed1993

Astrocytic and synaptic response to kindling in hippocampal subfield CA1. II. Synaptogenesis and astrocytic process increases to in vivo kindling.

Astrocytic glia are important for maintaining synaptic function during physiological activity. Recent hypotheses concerning epilepsy suggest a role for astrocytes in the control of neuronal excitability and in pathogenesis. This report provides morphological evidence that the periodic electrical stimulation used in the kindling model of epilepsy induces astrocytic hypertrophy and an increase in shaft synapse density in the CA1 region of the hippocampus. The Schaffer collateral pathway in the stratum radiatum of CA1 of five pairs of rats was kindled in vivo. Control animals received the same number of stimulations at a lower intensity and frequency. The animals were killed 24-48 h after reaching the criterion of five generalized seizures, and the brains were examined by electron microscopy. Kindling produced a 37% and 33% increase in the volume fraction of astrocytic processes in the middle and distal portions, respectively, of the s. radiatum in CA1. In the same tissue, the number (areal density) of shaft synapses was increased 25% in the s. radiatum of animals exhibiting generalized seizures. On the other hand, the areal density of degenerating synapses in both kindled and control animals was low and not significantly different. These results suggest that both synaptogenesis and hypertrophy of astrocytes contribute to an early stage of epileptogenesis when degenerative changes of the sort that might induce gliosis were not prominent in the tissue under study.

Animals↗
PubMed1993

A method for quantification of astrocytic processes reveals laminar differences in the dentate gyrus but not in CA1 of the hippocampal formation.

The distribution of astrocytic processes in the dentate gyrus molecular layer and CA1 subregion of the hippocampal formation was examined in 8-microns frozen sections from adult male rats. The stereological cycloid intersection method (Baddeley et al., 1986) was used to estimate surface density of glial fibrillary acidic protein-immunoreactive astrocytic processes. A distinct lamination pattern was delineated in the dentate gyrus which corresponds to the afferent input to this region. No such pattern was detectable in s. radiatum of CA1. By using this relatively new stereological method which utilizes a sensitive sampling scheme, it was possible to increase the reliability in reporting the distribution of fine processes while at the same time greatly reducing the amount of time necessary to estimate the amount of astrocytic processes in a given region.

Animals↗
PubMed1993

Central autonomic disorders.

Central autonomic dysfunctions can be due to primary (degenerative) or secondary disorders. Autonomic failure (AF) may be a major manifestation of multiple system atrophy (MSA) and idiopathic Parkinson's disease (IPD). In both MSA and IPD, AF is almost invariably associated with neuronal loss in the intermediolateral cell columns. Dysautonomia in MSA is early, severe, and progressive, including marked orthostatic hypotension and urinary incontinence and is complicated by respiratory disturbances, such as laryngeal stridor and sleep apnea. MSA/AF can be differentiated from primary (or pure) autonomic failure (PAF) without central nervous system involvement. PAF is mainly a disorder of the postganglionic neurons. In contrast to PAF, MSA/AF has preserved basal sympathetic activity, decreased cerebrospinal fluid (CSF) neurotransmitter markers, impaired vasopressin response to hypotension, and impaired adrenocorticotrophic hormone/beta endorphin response to hypoglycemia. AF in IPD is generally less severe than in MSA. Poor response to L-Dopa, abnormal urethral sphincter electromyography, and CSF markers may distinguish MSA from IPD. Secondary autonomic disorders may result from traumatic, vascular, inflammatory, demyelinating, or neoplastic lesions involving corticolimbic, hypothalamic, brainstem, or spinal autonomic network. These disorders can cause AF or autonomic hyperactivity, such as arrhythmia, hypertension, and hyperthermia. However, many disorders may only produce subclinical abnormalities.

Autonomic Nervous System Diseases↗
PubMed1992

Functional study of hepatitis delta virus large antigen in packaging and replication inhibition: role of the amino-terminal leucine zipper.

The large hepatitis delta antigen (HDAg) has been found to be essential for the assembly of the hepatitis delta virion. Furthermore, in a cotransfection experiment, the large HDAg itself, without the hepatitis delta virus (HDV) genome and small HDAg, could be packaged into hepatitis B surface antigen (HBsAg) particles. By deletion analysis, it was shown that the amino-terminal leucine zipper domain was dispensable for packaging. The large HDAg could also help in copackaging of the small HDAg into HBsAg particles without the need for HDV RNA. This process was probably mediated through direct interaction of the two HDAgs as a mutated large HDAg whose leucine zipper domain was deleted such that it could not help in copackaging of the small HDAg. This mutated large HDAg did not suppress HDV replication, suggesting that this effect is probably also via protein interaction. These results indicated that functional domains of the large HDAg responsible for packaging with HBsAg particles and for the trans-negative effect on HDV replication can be separated.

Antigens, Viral↗
PubMed1991

The large form of hepatitis delta antigen is crucial for assembly of hepatitis delta virus.

The virions of hepatitis delta virus (HDV) contain two species of HDV-specific protein, a large and a small form of hepatitis delta antigen (HDAg). We examined the role of individual HDAgs in virion assembly in cotransfection experiments. First, we constructed a replication-competent HDV mutant expressing only the small HDAg. When cotransfected with a plasmid expressing hepatitis B virus surface antigens to the HuH-7 cells, the mutant did not produce HDV virions, whereas the wild-type HDV clone did. Therefore, though the small HDAg is important for viral replication and is incorporated into the virus, the small-form delta antigen by itself is insufficient for virion formation. When the system was co-transfected with an additional plasmid providing the large HDAg, the HDV virion was then recovered. There was also evidence suggesting that the large HDAg could be copackaged into the HBsAg particles, without the presence of the HDV genome and the small HDAg. The results indicate a crucial role of the large HDAg in HDV assembly.

Antigens, Viral↗
PubMed1988

Dendritic pattern formation involves both oriented regression and oriented growth in the barrels of mouse somatosensory cortex.

The dendritic structure of neurons in the inner one-third of the wall of the barrels of somatosensory cortex was examined in animals at 10, 15, 20, 25, and 30 days of age. In adults, dendrites of these neurons project largely towards the barrel hollow. The amount of dendrite in the hemifield towards the barrel hollow, in which thalamic afferents terminate, increased with age, while the amount in the hemifield away from the hollow decreased, as measured by dendritic intersections with concentric rings. Loss of primary dendritic branches across these ages occurred both for dendrites arising on the side of the soma oriented away from the barrel hollow and for dendrites on the side of the soma nearest to the hollow. The loss of primary branches was much greater on the side away from the hollow. The amount of dendrite per primary branch increased for branches oriented towards the hollow, whereas it did not change or was somewhat reduced for those branches that remained on the side of the soma opposite the hollow. Thus both the selective loss of entire branches and the selective embellishment of others occur during the development of these somatosensory cortical structures.

Aging↗
PubMed1986

The lamination and connectivity of embryonic cerebral cortex transplanted into newborn rat cortex.

Sheets of frontal or occipital cerebral cortex were taken from embryonic day (E) 15 rat embryos and placed in shallow depressions made in the occipitoparietal region of newborn rats. These transplants developed normal patterns of lamination, which could be in an inverted orientation if the transplant itself was placed upside down. Irrespective of the cortical area of origin of the grafted tissue, the transplants consistently received projections from those host thalamic nuclei that were normally found to innervate the adjacent host cortex. This indicates that immature cortical tissue, up to at least E15, may not contain the information necessary to define the specific thalamocortical connections characteristic of individual areas. On the contrary, the observed input pattern may be the result of sprouting of fibers that normally innervated host cortical regions adjacent to the transplant. Similarly, callosal afferents to transplants seemed to be a direct extension of the callosal input to the host cortex immediately beneath the transplant. Results from HRP studies of callosal connections indicated that transplant efferents to the contralateral cortex are smaller in magnitude than their afferents. This may be related to the superficial location of the transplants, which may limit the access transplant efferents have to the white matter. This study suggests that, while the cortical lamination is largely determined intrinsically, the innervation of the cortex is influenced by the context in which it develops.

Animals↗
PubMed1985

Use of a species-specific antibody for demonstrating mouse neurons transplanted to rat brains.

A cell surface monoclonal antibody specific for mouse central nervous system neurons was used to identify mouse tissue transplanted to neonatal rat brains. Neuronal cell bodies and processes were stained in the transplants. Immature axons were stained growing out of the transplants into the host brain; and in mature brains unmyelinated axons and terminal plexuses were demonstrated. The technique allows a variety of studies to be performed on transplant-host interactions, especially in circumstances where the two are closely apposed.

Animals↗
PubMed1984

Transient and enduring morphological correlates of synaptic activity and efficacy change in the rat hippocampal slice.

This study examined anatomical correlates of: (1) long-term potentiation (LTP); (2) equivalent low frequency synaptic activity; (3) continuous high frequency synaptic activation which did not produce LTP; and (4) synaptic inactivation by high Mg2+/low Ca2+ incubation in hippocampal subfield CA1 in the in vitro slice, and examined the persistence of changes at 10-15 min, 2 h and 8 h after stimulation. After potentiating stimulation (6 trains at 100 Hz for 1 s or 200 Hz for 0.5 s), compared to an equivalent number of low frequency stimuli (1 Hz for 600 s), there were increases in numbers of shaft and sessile spine synapses (synapses on stubby, headless spines). This suggested an increase in the number of shaft synapses onto inhibitory interneurons and/or an enhancement of synapse formation on pyramidal neurons possibly involving initial formation of shaft synapses and a transition from shaft, to sessile spine, to full grown spine synapses. Postsynaptic spine heads also assumed a rounder shape, as indicated by decreases in spine perimeter to area ratios, contact lengths, and the percentage of 'cup' shaped spines. There was no effect of potentiating stimulation on bouton or spine areas. After continuous high frequency synaptic activation (40 Hz or 100 Hz for 10 min), which produced no apparent LTP, there were no changes in synapse numbers or spine head shape parameters. However, in contrast to effects of LTP, there was an increase in bouton mitochondrial area and a marginal increase in bouton area compared to the low frequency condition. Inactivation did not affect any of these measures. LTP-associated increases in numbers of shaft and sessile spine synapses persisted over an 8 h incubation period, while the effect on spine shape disappeared after 2 h. Physiologically-demonstrable LTP persisted over the 8 h period. Effects of continuous high level activation on mitochondrial and bouton areas were even more transient, disappearing 2 h after stimulation. These findings: (1) confirm previously reported effects of potentiating stimulation on synapse numbers and spine shape; (2) indicate that spine shape changes are not necessary for the maintenance of LTP; and (3) indicate that continuous high frequency activation which does not produce potentiation has different and non-persisting effects from potentiating stimulation.

Animals↗