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Biomedical subjects

F F Liu

Publications and source records attributed to F F Liu.

82 records · Page 5Linked to original sources
PubMedDate not supplied

Primary carcinoma involving the petrous temporal bone.

Between 1975 and 1985, 29 patients with the diagnosis of carcinoma of the petrous temporal bone were seen at the Princess Margaret Hospital. Twenty-seven carcinomas were graded: 13 were well-differentiated; the remaining 14 were either moderately or poorly differentiated tumors. Fifteen patients were managed with a combination of surgery and radiotherapy, 13 were treated with radiotherapy only, and one patient was treated by surgery alone. Median follow-up time was 6.1 years, and the 5-year actuarial local control and cause-specific survival rates for the entire group were 40% and 50%, respectively. Age greater than 60 years, poor grade of tumor, and involvement of the facial nerve were three significant variables associated with poor outcome. A superior 5-year actuarial local control was achieved with surgery plus postoperative radiotherapy (54%) compared to other treatment approaches. Based on the results from this review, we would continue to recommend a combined modality approach of surgery followed by postoperative radiotherapy in the management of this rare, but life-threatening disease.

Adenocarcinoma↗
PubMedDate not supplied

Benign parotid adenomas: a review of the Princess Margaret Hospital experience.

BACKGROUND: The morbidity of treating benign parotid tumors is an important issue because the majority of patients are young. We therefore undertook this study to evaluate the outcome for these patients treated at the Princess Margaret Hospital. METHODS: A retrospective review was conducted on all patients registered with benign parotid tumors between 1970 and 1987. RESULTS: Seventy-six patients were included in this review; postoperative radiotherapy (XRT) was administered to 55 patients. Median follow-up time was 12.5 years. Postoperative XRT was particularly important for patients with recurrent disease. The risk of both temporary and permanent facial nerve paralyses increased with each operation. No patients in this study developed a malignancy. CONCLUSIONS: We recommend that all patients with benign parotid tumors be treated with a complete parotidectomy with preservation of the facial nerve. Consideration to postoperative XRT should be given to patients in whom there was tumor spillage, residual disease, or recurrences.

Adenoma↗
PubMedDate not supplied

Adenoviral p53 gene therapy promotes heat-induced apoptosis in a nasopharyngeal carcinoma cell line.

BACKGROUND: It has previously been demonstrated that Ad5CMV-p53 gene transfer, either used alone or delivered concomitantly with ionizing radiation, resulted in cytotoxicity mediated by apoptosis in nasopharyngeal carcinoma (NPC) cell lines. In this study, a novel approach was evaluated of combining Ad5CMV-p53 gene therapy with hyperthermia (HT), in the CNE-1 NPC cell line, which harbours a mutation in codon 249 of the p53 gene. MATERIALS AND METHODS: CNE-1 cells were infected using either Ad5CMV-p53 or Ad5CMV-B-gal, followed, 24 h later, by HT (43 degrees C x 0-2 h). Protein was extracted for Western blot analysis, and apoptosis was evaluated using acridine-orange ethidium bromide staining, followed immediately by fluorescent microscopy examination for the proportion of cells displaying morphologic features of apoptosis. RESULTS: Ad5CMV-p53 gene therapy combined with HT resulted in a dose-dependent cytotoxicity with less than 1% clonogenic survival when 10 pfu/cell of Ad5CMV-p53 was combined with 2 h heating at 43 degrees C. Western blotting demonstrated that treatment with Ad5CMV-p53 resulted in the rapid expression of p53, which was minimally affected by HT. The inducible form of hsp70 was maximally expressed at 48 h post-HT, with minimal effect when cells were additionally treated with Ad5CMV-p53. Clonogenic cytotoxicity was associated with the development of apoptosis, with up to 70% of CNE-1 cells displaying morphologic features of apoptosis after the combination treatments. CONCLUSION: Based on the shapes of the clonogenic survival curves, Ad5CMV-p53 gene therapy and HT appear to interact in an additive manner, suggesting the therapeutic potential of this combined treatment approach for patients with NPC.

Adenoviridae↗
PubMedDate not supplied

Echo-guided lymphatic drainage by fine-needle aspiration in persistent isolated septated fetal nuchal cystic hygroma.

We report two cases of large, persistent, isolated, fetal nuchal cystic hygromas that underwent echo-guided lymphatic drainage by fine-needle aspiration during the second and third trimesters. Multiple punctures and fluid tapping from cystic hygromas under sonographic guidance proved to be easy procedures and not deleterious to the fetuses. The decompression effect caused by lymphatic drainage in utero can prevent polyhydramnios, irreversible fetal facial deformity and progression to hydrops fetalis. Furthermore, when carried out during the third trimester, especially before delivery, it helps avoid birth injury, dystocia and neonatal asphyxia.

Adult↗
PubMedDate not supplied

Effect of vascular occlusion on tumour temperatures during superficial hyperthermia.

Tumour temperature heterogeneity during hyperthermia has been attributed to irregular tumour vascular perfusion. We have compared temperature distributions in human tumours subjected to superficial hyperthermia under conditions of normal and occluded blood flow. Three patients with recurrent malignant melanoma on the leg were treated with radiation followed by hyperthermia 60-90 min later on days 1, 8 and 22. Heating (15-30 min) with normal blood flow was followed by 15 min of heating with tourniquet occlusion, although the tourniquet had to be intermittently released when the patients complained of discomfort. Hyperthermia was delivered using either a 1.4 MHz ultrasound or 915 MHz microwave applicator. Temperatures were monitored using superficial and interstitial thermometers in tumour and normal tissues. When the tourniquet was applied, the amount of power required to maintain peak temperatures was decreased by a factor of 3-10. With normal blood flow, there was a significant degree of temperature heterogeneity within the treatment volume, both within normal and tumour tissues, which improved with tourniquet application. The T90 and T50 indices increased both in normal tissues and tumour following the tourniquet occlusion, with the temperature increments being greater for normal tissues. Temperatures at depth were increased despite the reduction in applied power and the temperature profiles were smoother when the tourniquet was applied. No cutaneous, vascular or neuromuscular side effects were observed amongst these three subjects either acutely or at 1 month follow-up. These studies demonstrate directly that the temperature heterogeneity which exists in human tumours subjected to external heating can be reduced by occluding the blood supply.

Aged↗
PubMedDate not supplied

A variable microwave array attenuator for use with single-element waveguide applicators.

The effectiveness of hyperthermia treatments is often limited by temperature inhomogeneity that arises in the treatment field due to variable tissue properties and blood flow. Moreover, blood flow can change during a treatment, leading to the formation of hot and cool areas even if the initial temperature distribution is uniform. A variable microwave array attenuator has been constructed, that will enable the field patterns of single element microwave waveguide hyperthermia applicators to be altered during treatment, to improve temperature homogeneity. The coupling bolus was designed with an array of individually controlled elements, each filled with a microwave absorbing saline solution. Additions or withdrawals of saline are made to alter the power deposition in a specific area of the treatment field. Thermographic measurements were made in muscle equivalent phantom materials, with the bolus/waveguide assembly. Results showed that the variable array attenuator was able to significantly alter the heating pattern of a large waveguide applicator.

Biophysical Phenomena↗
PubMedDate not supplied

The potential role of HSP70 as an indicator of response to radiation and hyperthermia treatments for recurrent breast cancer.

Twenty-three patients with recurrent breast cancer participating in a Phase III trial evaluating radiotherapy (XRT) with or without hyperthermia (HT) were included in a parallel study of heat shock protein (hsp) expression. The patients had core biopsies and/or fine needle aspirates (FNA) performed on their tumours, before and after treatment. These were analysed for hsp content using immunohistochemical staining with a monoclonal antibody to the inducible form of hsp 70. The proportion of samples containing identifiable cancer cells was greater for the core biopsy specimens (80%) than with FNA (60%). Staining intensity was analysed using either the majority score, i.e. the staining intensity (on a relative scale from 0 to 3) for the largest proportion of tumour cells, or the arithmetic score, which is the sum of the product of percentage of tumour cells and their staining intensity. The staining intensity for hsp's after treatment correlated inversely with the probability of attaining a complete response (CR). Specifically, the median and maximum scores for the biopsy specimens were significantly inversely related to the probability of attaining CR. The results suggest that this technique may be useful in predicting for thermotolerance development, though more data is needed to confirm the utility of the technique. Results from this study corroborate data from other clinical studies which suggest that tumours with elevated hsp levels may demonstrate resistant biologic behaviour.

Biopsy↗
PubMedDate not supplied

Effect of simultaneous pulsed hyperthermia and pulsed radiation treatment on survival of SiHa cells.

Relatively mild temperatures (40-41.5 degrees C) can sensitize human cells to radiation without the development of thermal tolerance to radiosensitization. Therefore there may be a therapeutic benefit to adding mild hyperthermia to brachytherapy regimens for the treatment of cancer. However, the required heating times are long (approximately 48 h) which renders this approach somewhat impractical. A novel alternative is to combine pulsed brachytherapy with pulsed hyperthermia to enable the total radiation dose to be given at an elevated temperature while the total heating time is kept short. A treatment schedule in which 1 Gy radiation pulses were given once per hour during 5-min heating pulses also delivered once per hour, was investigated in vitro in the human cervical carcinoma line, SiHa. The degree of cytotoxicity and thermoradiosensitization of the cells were assessed by cell survival using the colony forming assay. Cells were exposed to pulsed hyperthermia alone (5 min at 45 degrees C, delivered once per hour), acute hyperthermia alone (45 degrees C), pulsed radiation alone (1 Gy per hour), acute radiation alone, and simultaneous pulsed hyperthermia and pulsed radiation. Pulsed heating alone caused little cytotoxicity. However when pulsed heating was added to pulsed radiation, the level of cytotoxicity was greater than for pulsed radiation alone or acute radiation alone. The effect was also greater than would be predicted from a simple additive effect of pulsed radiation and pulsed heating. In conclusion, pulsed heating at 45 degrees C sensitized cells to pulsed radiation without the development of thermal tolerance.

Cell Survival↗