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Biomedical subjects

C K Chung

Publications and source records attributed to C K Chung.

88 records · Page 5Linked to original sources
PubMed1980

Early corticosteroid administration in experimental radiation-induced heart disease.

The ability of dexamethasone (DEX) to reduce the severity of the late stage of radiation-induced heart disease (RIHD) was assessed in 25 New Zealand white rabbits. Ten rabbits served as unirradiated controls (CONT). In Group A, seven rabbits received intravenous DEX prior to irradiation and every 24 hours for three consecutive days. DEX was not administered to the eight rabbits in Group B. At 100 days postirradiation, the severity of the late state was determined by microscopic examination (MICRO) for myocardial fibrosis and determination of myocardial hydroxyproline content (MHP). Myocardial fibrosis was evident in Groups A (40%) and B (80%) while none was present in CONT by MICRO. One rabbit in Group B with no fibrosis by MICRO had abnormally increased MHP. MHP was significantly increased in Groups A and B, as compared to CONT (p less than 0.01). In addition to less fibrosis by MICRO, Group A demonstrated a significant reduction of MHP when compared to Group B (p less than 0.05). Determination of MHP may be superior to MICRO in the detection of the late stage of RIHD. Also, early DEX administration appears to reduce myocardial collagen content (fibrosis) in this experimental model.

Animals↗
PubMed1980

Radiotherapy in the management of primary malignancies of the hard palate.

Primary malignancies of the hard palate are rare. Only 66 cases have been seen at the University of Virginia Hospital in the 43 years from 1932 through March 1975. These have been reviewed with regard to age, sex, race, histology and clinical presentation. There was 32 squamous cell carcinomas, 25 salivary gland tumors and 9 nonepithelial malignancies. The nonepithelial malignancies were a diverse group and are not considered further. The results of treatment for the squamous cell carcinoma group and salivary gland tumors have been analyzed by stage and mode of therapy. Although no great improvement in the results of surgery or combined therapy have been observed over the years in the squamous cell carcinoma group, there has been a dramatic improvement in the results of treatment with radiation therapy from the orthovoltage era to the super-voltage era. Primary control with radiation therapy for the squamous cell carcinoma group was 2/5 (40%) in the orthovoltage era and 7/7 (100%) in the supervoltage era. Surgery would appear to be the appropriate treatment for salivary gland tumors with possibly a place for combined therapy. Radiation therapy proved useful in salvaging certain surgical failures. The time of appearance of local recurrence following initial therapy, the incidence of distant metastases and second primary tumors were analyzed and are presented.

Adult↗
PubMed1979

Postoperative beta irradiation in the treatment of pterygium.

High recurrence rates are reported after surgical treatment of pterygia. With the use of beta irradiation, the recurrence rate drops dramatically. This paper describes technic and dosage used in a group of patients receiving postoperative beta irradiation. Two thirds of these patients, however, had at least two surgical procedures. A recurrence rate of 3.5% was observed, with no apparent morbidity.

Adult↗
PubMed1979

Tumor sterilization following high-dose pre-operative irradiation for advanced cancer of the larynx or pyriform sinus.

Twenty-two patients with advanced laryngeal cancer and 5 with advanced pyriform sinus cancer were given 51 Gy (5,100 rad) followed by surgical resection. In 10 (45%) of patients with laryngeal cancer, no tumor was found at the primary site pathologically; 15 (68%) had negative neck specimens. All of those with pyriform sinus cancer had positive specimens. Eighteen patients with laryngeal cancer are free of disease. In contrast, only 1 with pyriform sinus cancer is free of disease; 1 has had a local recurrence and 3 have had metastases. The data suggest that 51 Gy (5,100 rad) are insufficient to sterilize pyriform sinus cancer; higher doses together with adjuvant chemotherapy are needed.

Adult↗
PubMed1978

Malignant salivary gland tumors of the palate.

Twenty patients with malignant salivary gland tumors of the hard and soft palate were seen at the University of Virginia Hospital from 1956 through 1975. The characteristics of the tumors, including symptoms and histology are reviewed and the results of treatment are analyzed. In particular, the place of radiotherapy in their management has been examined. Primary control by initial surgery alone was achieved in 60% (9/15) of the cases, and, when those patients who received radiotherapy for residual disease or salvage are included, the primary control was 94% (16/17). Five- and ten-year determinate survival rates were 88% and 67%, respectively. From this retrospective analysis and a review of the literature, it appears that radiotherapy has made a very positive contribution to the management of these tumors.

Adenocarcinoma↗
PubMedDate not supplied

Fluoride release and cariostatic ability of a compomer and a resin-modified glass ionomer cement used for orthodontic bonding.

OBJECTIVES: The aims of this study were to compare the local and systemic uptake of fluoride released from a compomer material (Dyract Ortho) and a resin-modified glass ionomer cement (Vitremer) with that of a conventional resin adhesive (Right-On) and to compare the cariostatic ability of each of the test materials with that of the resin control. METHODS: Twenty six patients were randomly allocated to have a bracket bonded to a premolar on one side of the arch with one of the test materials and on the opposite side with the control material. Premolars destined for extraction as part of an orthodontic treatment plan were selected for bonding. A non-fluoride toothpaste was used by all participants for 4 weeks prior to bracket bonding and throughout the 4 week trial period. Fluoride release was measured in saliva, plaque and urine samples taken pre-bonding and 4 weeks post-bonding. Enamel demineralisation was assessed by scoring the buccal surface of each extracted tooth using a caries index. RESULTS: Neither Vitremer nor Dyract Ortho altered salivary or urinary fluoride concentration significantly 4 weeks post-bonding but plaque fluoride concentration increased significantly around premolars bonded with Vitremer. The test materials as a combined group were associated with significantly less demineralisation than the control material but there was no significant difference in cariostatic ability detected between either Dyract Ortho or Vitremer when each group was compared separately with the control. CONCLUSIONS: Fluoride released from Dyract Ortho or Vitremer is likely to exert a local and not a systemic effect. In a 4-week clinical study, the cariostatic ability of the fluoride-releasing cements, as a combined group, was superior to that of the non-fluoride releasing control but there was no significant difference in cariostatic ability between the two test materials when each test group was compared separately with the control.

Adolescent↗
PubMedDate not supplied

Photoreceptor inner segments in monkey and human retina: mitochondrial density, optics, and regional variation.

The present work quantifies aspects of photoreceptor structure related to mitochondria, inner segment dimensions, and optical properties, as a basis for furthering our understanding of rod and cone function. Electron-microscopic analyses were performed on the retina of one stumptail macaque (Macaca arctoides) to obtain stereological measurements of ellipsoid mitochondrial density, and sizes and shapes of outer and inner segments. In addition, the distribution of mitochondria and the optical properties of human foveal cones were examined with electron microscopy and Nomarski differential interference contrast (NDIC) imaging. Mitochondria comprised 74-85% of cone ellipsoids and 54-66% of rod ellipsoids in macaque. Ellipsoid volume increased with eccentricity by 2.4-fold for rods and more than 6-fold for cones over eccentricities to 12.75 mm, while the volume of the outer segment supported by the ellipsoid was essentially constant for both rods and cones. Per unit volume of outer segment, cones contained ten times as much mitochondria as rods. In human fovea, as in the rest of the retina, most cone mitochondria were located in the distal inner segment. In the foveal center, however, there are also mitochondria in the myoid, as well as in the outer fiber, proximal to the external limiting membrane (ELM). Analyses of the optical aperture of human foveal cones, the point at which their refractive index clearly differs from the extrareceptoral space, showed that it correlated well with the location of mitochondria, except in the foveal center, where the aperture appeared proximal to the ELM. While mitochondria have an important metabolic function, we suggest that the striking differences between rods and cones in mitochondrial content are unlikely to be determined by metabolic demand alone. The numerous cone mitochondria may enhance the waveguide properties of cones, particularly in the periphery.

Animals↗
PubMedDate not supplied

Complications of laryngectomy and neck dissection following planned preoperative radiotherapy.

One hundred sixty-nine patients with carcinoma involving the larynx treated with surgery, combined preoperative radiotherapy plus surgery, or failed curative radiotherapy with surgical salvage have been evaluated with respect to complications. Major complications occurred at approximately the same rate with all three modes of therapy. Major complications had generally a later onset and healed less rapidly in the preoperative radiotherapy group. Minor complications occurred more frequently in irradiated patients than in nonirradiated patients. When evaluating postoperative complications in irradiated patients the time interval must be extended beyond the immediate span because of delayed onset.

Fistula↗
PubMedDate not supplied

Usefulness of single voxel proton MR spectroscopy in the evaluation of hippocampal sclerosis.

OBJECTIVE: The purpose of our study was to determine the ability of H-1 MR spectroscopy (MRS) to lateralize the lesion in patients with hippocampal sclerosis. MATERIALS AND METHODS: Twenty healthy volunteers and 25 patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis were included. This diagnosis was based on the presence of unilateral atrophy and/or high T2 signal intensity of the hippocampus. Singlevoxel H-1 MRS was carried out on a 1.5-T unit using PRESS sequence (TE, 136 msec). Spectra were obtained from hippocampal areas bilaterally with volumes of interest (VOIs) of 6.0 cm(3) and 2.25 cm(3) in healthy volunteers, and of either 6.0 cm(3) (n = 14) or 2.25 cm(3) (n = 11) in patients. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from relative peak height measurements. The capability of MRS to lateralize the lesion and to detect bilateral abnormalities was compared with MR imaging diagnosis as a standard of reference. RESULTS: In healthy volunteers, NAA/Cho and NAA/Cr ratios were greater than 0.8 and 1.0, respectively. In patients, the mean values of these ratios were significantly lower on the lesion side than on the contralateral side, and lower than those of healthy volunteers (p <.05). The overall correct lateralization rate of MRS was 72% (18/25); this rate was lower with a VOI of 6.0 cm(3) than of 2.25 cm(3) (64% versus 82%, p <.05). Bilateral abnormalities on MRS were found in 24% (6/25) of cases. CONCLUSION: Although its rate of correct lateralization is low, single-voxel H-1 MRS is a useful and promising diagnostic tool in the evaluation of hippocampal sclerosis, particularly for the detection of bilateral abnormalities. To improve the diagnostic accuracy of H-1 MRS, further investigation, including the use of a smaller VOI and measurement of the absolute amount of metabolites, are needed.

Adult↗
PubMedDate not supplied

Hippocampal sclerosis: correlation of MR imaging findings with surgical outcome.

OBJECTIVE: Atrophy and a high T2 signal of the hippocampus are known to be the principal MR imaging findings of hippocampal sclerosis. The purpose of this study was to determine whether or not individual MRI findings correlate with surgical outcome in patients with this condition. MATERIALS AND METHODS: Preoperative MR imaging findings in 57 consecutive patients with pathologically-proven hippocampal sclerosis who underwent anterior temporal lobectomy and were followed-up for 24 months or more were retrospectively reviewed, and the results were compared with the postsurgical outcome (Engel classification). The MR images included routine sagittal T1-weighted and axial T2-weighted spin-echo images, and oblique coronal T1-weighted 3D gradient-echo and T2-weighted 2D fast spin-echo images obtained on either a 1.5 T or 1.0 T unit. The images were visually evaluated by two neuroradiologists blinded to the outcome; their focus was the presence or absence of atrophy and a high T2 hippocampal signal. RESULTS: Hippocampal atrophy was seen in 96% of cases (55/57) [100% (53/53) of the good outcome group (Engel class I and II), and 50% (2/4) of the poor outcome group (class III and IV)]. A high T2 hippocampal signal was seen in 61% of cases (35/57) [62% (33/53) of the good outcome group and 50% (2/4) of the poor outcome group]. All 35 patients with a high T2 signal had hippocampal atrophy. 'Normal' hippocampus, as revealed by MR imaging, occurred in 4% of patients (2/57), both of whom showed a poor outcome (Engel class III). The presence or absence of hippocampal atrophy correlated well with surgical outcome (p<0.01). High T2 signal intensity did not, however, significantly correlate with surgical outcome (p>0.05). CONCLUSION: Compared with a high T2 hippocampal signal, hippocampal atrophy is more common and correlates better with surgical outcome. For the prediction of this, it thus appears to be the more useful indicator.

Adult↗
PubMedDate not supplied

Multifocal primary CNS T cell lymphoma of the spinal cord.

The majority of primary central nervous system lymphomas (PCNSL) are of B cell origin, and those of T cell origin are a distinct rarity. Furthermore, spinal cord involvement of T cell PCNSL is extremely rare and only a small number of cases have been reported. The authors report a case of multifocal T cell PCNSL mainly involving the intramedullary (IM) portion ofthe spinal cord in a 57-year-old woman. Neurological examination showed right leg weakness and hypesthesia below the T10 level. Magnetic resonance images revealed multiple well enhancing masses in the IM portion ofthe cervical and thoracic spinal cord and the cerebellum. Cytological examination of the cerebrospinal fluid revealed no malignant cells. As the mass at the C7 level was the largest among multiple masses, open biopsy was performed at that level. Histopathological examination confirmed malignant peripheral T cell lymphoma, unspecified (PTCL-U), small- and medium-sized cell type. Clinical and laboratory investigations failed to reveal any evidence of lymphomatous deposits elsewhere in the body. After biopsy, the patient received cranio-spinal irradiation, which included the whole brain and the spinal neuraxis. The clinical course, pathological findings and treatments are discussed and a review of the literature included.

Female↗
PubMedDate not supplied

Temporal lobe epilepsy caused by choroid plexus papilloma in the temporal horn.

Choroid plexus papilloma (CPP) arising in the temporal horn is rare in adult population, and to the best of our knowledge, there has been no report of such a case with temporal lobe epilepsy (TLE). The authors describe a unique case of a 27-year-old woman who was diagnosed as TLE and was found to have a CPP in the temporal horn. Choroid plexus papilloma of the temporal horn, even though rare, can be found in adult population and be causally related to temporal lobe epilepsy.

Adult↗