Development of a portable analyzer with polymer lab-on-a-chip (LOC) for continuous sampling and monitoring of Pb(II).

A new portable analyzer with polymer lab-on-a-chip (LOC) has been designed, fabricated and fully characterized for continuous sampling and monitoring of lead (Pb(II)) in this work. As the working electrodes of the sensor, bismuth (Bi (III)) which allowed the advantage of being more environmentally friendly than traditional mercury drop electrodes was used, while maintaining similar sensitivity and other desirable characteristics. The size of a portable analyzer was 30 cmx23 cmx7 cm, and the weight was around 3 kg. The small size gives the advantage of being portable for field use while not sacrificing portability for accuracy of measurement. Furthermore, the autonomous system developed in coordination with the development of new polymer LOC integrated with electrochemical sensors can provide an innovative way to monitor surface waters in an efficient, cost-effective and sustainable manner.

Crystal orientation and thickness dependence of the superconducting transition temperature of tetragonal FeSe1-x thin films.

Superconductivity was recently found in the tetragonal phase FeSe. A structural transformation from tetragonal to orthorhombic (or monoclinic, depending on point of view) was observed at low temperature, but was not accompanied by a magnetic ordering as commonly occurs in the parent compounds of FeAs-based superconductors. Here, we report the correlation between structural distortion and superconductivity in FeSe(1-x) thin films with different preferred growth orientations. The films with preferred growth along the c axis show a strong thickness dependent suppression of superconductivity and low temperature structural distortion. In contrast, both properties are less affected in the films with (101) preferred orientation. These results suggest that the low temperature structural distortion is closely associated with the superconductivity of this material.

Ionizing radiation absorption of vascular surgeons during endovascular procedures.

OBJECTIVE: Endovascular procedures have become an integral part of a vascular surgeon's practice. The exposure of surgeons to ionizing radiation and other safety issues have not been well studied. We investigated the radiation exposure of a team of vascular surgeons in an active endovascular unit and compared yearly dosages absorbed by various body parts among different surgeons. Patients' radiation exposure was also assessed. METHODS: The radiation absorption of a team of vascular surgeons was prospectively monitored in a 12-month period. During each endovascular procedure, the effective body, eye, and hand radiation doses of all participating surgeons were measured by mini-thermoluminescent dosimeters (TLD) attached at the chest level under a lead apron, at the forehead at eye level, and at the hand. The type of procedure, fluoroscopy machine, fluoroscopy time, and personal and operating theatre radiation protection devices used in each procedure were also recorded. One TLD was attached to the patient's body near the operative site to measure the patient's dose. The yearly effective body, eye, and hand dose were compared with the safety limits of radiation for occupational exposure recommended by the International Commission on Radiation Protection (ICRP). The radiation absorption of various body parts per minute of fluoroscopy was compared among different surgeons. RESULTS: A total of 149 consecutive endovascular procedures were performed, including 30 endovascular aortic repairs (EVAR), 58 arteriograms with and without embolization (AGM), and 61 percutaneous transluminal angioplasty and stent (PTA/S) procedures. The cumulative fluoroscopy time was 1132 minutes. The median yearly effective body, eye, and hand dose for the surgeons were 0.20 mSv (range, 0.13 to 0.27 mSv), 0.19 mSv (range, 0.10 to 0.33 mSv) and 0.99 mSv (0.29 to 1.84 mSv) respectively, which were well below the safety limits of the ICRP. The mean body, eye, and hand dose of the chief surgeon per procedure were highest for EVAR. A significant discrepancy was observed for the average hand dose per minute of fluoroscopy among different surgeons. The mean radiation absorption of patients who underwent EVAR, AGM, and PTA/S was 12.7 mSv, 13.6 mSv, and 3.4 mSv, respectively. CONCLUSION: With current radiation protection practice, the radiation absorbed by vascular surgeons with a high endovascular workload did not exceed the safety limits recommended by ICRP. Variations in practice, however, can result in significant discrepancy of radiation absorption between surgeons.

Preliminary results of radiation dose escalation for locally advanced nasopharyngeal carcinoma.

PURPOSE: To study the safety and efficacy of dose escalation in tumor for locally advanced nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: From September 2000 to June 2004, 50 patients with T3-T4 NPC were treated with intensity-modulated radiotherapy (IMRT). Fourteen patients had Stage III and 36 patients had Stage IVA-IVB disease. The prescribed dose was 76 Gy to gross tumor volume (GTV), 70 Gy to planning target volume (PTV), and 72 Gy to enlarged neck nodes (GTVn). All doses were given in 35 fractions over 7 weeks. Thirty-four patients also had concurrent cisplatin and induction or adjuvant PF (cisplatin and 5-fluorouracil). RESULTS: The average mean dose achieved in GTV, GTVn, and PTV were 79.5 Gy, 75.3 Gy, and 74.6 Gy, respectively. The median follow-up was 25 months, with 4 recurrences: 2 locoregional and 2 distant failures. All patients with recurrence had IMRT alone without chemotherapy. The 2-year locoregional control rate, distant metastases-free and disease-free survivals were 95.7%, 94.2%, and 93.1%, respectively. One treatment-related death caused by adjuvant chemotherapy occurred. The 2-year overall survival was 92.1%. CONCLUSIONS: Dose escalation to 76 Gy in tumor is feasible with T3-T4 NPC and can be combined with chemotherapy. Initial results showed good local control and survival.

Concurrent and adjuvant chemotherapy for nasopharyngeal carcinoma: a factorial study.

PURPOSE: To study the efficacy of concurrent chemoradiotherapy (CRT) and adjuvant chemotherapy (AC) for nasopharyngeal carcinoma (NPC). PATIENTS AND METHODS: Patients with Ho's stage T3 or N2/N3 NPC or neck node > or = 4 cm were eligible. Patients were randomly assigned to have radiotherapy (RT) or CRT with uracil and tegafur and to have AC or no AC after RT/CRT. AC comprised alternating cisplatin, fluorouracil, vincristine, bleomycin, and methotrexate for six cycles. There were four treatment groups: A, RT; B, CRT; C, RT and AC; D, CRT and AC. For CRT versus RT, groups B and D were compared with groups A and C. For AC versus no AC, groups C and D were compared with groups A and B. RESULTS: Three-year failure-free survival (FFS) and overall survival (OS) for CRT versus RT were 69.3% versus 57.8% and 86.5% versus 76.8%, respectively (P =.14 and.06; n = 110 v 109). Distant metastases rate (DMR) was significantly reduced with CRT (14.8% v 29.4%; P =.026). Locoregional failure rates (LRFR) were similar (20% v 27.6%; P =.39). Three-year FFS and OS for AC versus no AC were 62.5% versus 65% and 80.4% versus 83.1%, respectively (P =.83 and.69; n = 111 v 108). DMR and LRFR were not reduced with AC (P =.34 and.15, respectively). Cox model showed CRT to be a favorable prognostic factor for OS (hazard ratio, 0.42; P =.009). CONCLUSION: An improvement in OS with CRT was observed but did not achieve statistical significance. The improvement seemed to be associated with a significant reduction in DMR. AC did not improve outcome.

Patient effective dose from sentinel lymph node lymphoscintigraphy in breast cancer: a study using a female humanoid phantom and thermoluminescent dosemeters.

The aim of this study was to measure the dose delivered to patients undergoing sentinel lymph node lymphoscintigraphy by taking into account both the transmission scan dose using a (57)Co flood source and the (99)Tc(m) internal emission dose. An adult female humanoid phantom and a set of thermoluminescent dosimeters were used in the measurements. The choice of measurement organs in the humanoid was guided by the recommendations described in the International Commission on Radiological Protection report number 60. A (57)Co flood source was used in external transmission to irradiate the humanoid at posterior, left lateral, left posterior oblique, right lateral and right posterior oblique positions. Four (99)Tc(m) deposits as internal emission sources were used to simulate patient peritumoural injection. The individual effective doses for external transmission and internal emission, normalized to the cumulated activity and expressed in micro Sv(MBq x h)(-1) were then calculated. The effective dose for a transmission scan was on average 0.061 micro Sv(MBq x h)(-1) for each (57)Co flood source position and for internal emission 0.312 micro Sv(MBq x h)(-1) and 0.291 micro Sv(MBq x h)(-1) for left and right breast injection, respectively. Using these results, the effective dose from both transmission and emission sources can be calculated according to the nuclear medicine scanning protocol and surgical procedure of the individual institution. For our protocols, the patient receives a maximum effective dose of 52 micro Sv for the 1 day protocol (18 MBq injection) and 204 micro Sv for the 2 day protocol (74 MBq injection) if only the sentinel lymph node is excised. If other tissues containing radioactivity are removed, the patient effective dose will be reduced by about 50% and 6%, respectively, for the 1 day protocol and 2 day protocol. Although the doses are low compared with other radiological examinations, the results are informative for patients concerned about radiation exposure for this new imaging technique.

Long term results of radioactive gold grain implantation for the treatment of persistent and recurrent nasopharyngeal carcinoma.

BACKGROUND: Brachytherapy is useful for the reirradiation of nasopharyngeal carcinoma. In the current study, the long term treatment results of permanent radioactive gold(198) grain interstitial implantation in patients with persistent and recurrent nasopharyngeal carcinoma were reviewed. METHODS: Gold grain implantation was performed under direct vision with a split palate approach to provide 60 grays (Gy) 0.5 cm away from the plane of implantation. Between August 1986 and May 1999, 106 patients were treated with gold grain implantation (45 patients for persistent disease, 53 patients for first recurrence, and 8 patients for second recurrence in the nasopharynx). All patients had histologically proven disease by biopsy before undergoing implantation. RESULTS: Patients with persistent disease and those with first recurrence did well with the gold grain implantation. The 5-year local control rates for patients with persistent disease, first recurrence, and second recurrence in the nasopharynx were 87.2%, 62.7%, and 23.4%, respectively (P = 0.0004). The 5-year metastasis free survival rates were 68.1%, 60.3%, and 40%, respectively, for the 3 groups (P = 0.048). The overall survival rates at 5 years for the 3 groups were 79.1%, 53.6%, and 42.9%, respectively (P = 0.0047). Patients with computed tomography evidence of disease extension outside the nasopharynx had a lower local control rate compared with patients whose disease was confined to the nasopharynx (5-year local control rate of 52% vs. 72.3%; P = 0.031). The size of the lesion was not found to be an independent prognostic factor for local control after implantation. Multivariate analysis showed only an indication for implantation (persistent disease, first recurrence, and second recurrence) to be a significant prognostic factor for local control. Complications attributed to gold grain implantation included headache, palatal fistula, and mucosal radiation necrosis at the site of implantation, and were reported to occur in 28.3%, 18.9%, and 16%, respectively, of patients. CONCLUSIONS: For selected patients with disease confined to the nasopharynx, gold grain implantation is an effective salvage treatment for persistent and recurrent nasopharyngeal carcinoma.

A new tool for dose conformity evaluation of radiosurgery treatment plans.

PURPOSE: A novel method for dose conformity evaluation of treatment plans produced by the stereotactic radiosurgery treatment planning system is postulated. METHODS AND MATERIALS: By consolidating the information contained in the integral dose-volume histogram and the treatment volume ratio, a plot of treatment volume ratio versus percentage dose may be considered as a useful tool for plan evaluation. To validate the suggested argument, two simple experiments simulating the conformal and nonconformal cases were conducted on the geometric phantom that is commercially available from Radionics. An actual patient treatment plan is also included to explore the effectiveness of the proposed parameters. It is an attempt to establish the baseline of a conformal plan. RESULTS: A plot showed the ability to give the user an idea whether the size of the collimator was adequate to cover the delineated lesion when the user-defined criteria had been in place. Two parameters, namely take-off dose (TOD) and take-off volume (TOV) were defined. The former was defined as the maximum dose level found on the surface of the target volume. The TOD is also the maximum possible dose to be received by the adjacent normal tissue. The latter was defined as the percentage of the target volume that received the TOD. Another parameter, irradiated percentage volume (IPV), was defined here as the percentage of the target volume receiving at least the prescribed dose. When the prescribed dose is also the TOD, the IPV becomes the TOV. They were proved to be effective in evaluating the dose conformity. Another term known as equivalent fall-off distance (EFOD) was defined as the equivalent radial distance calculated between two isodose lines. In fact, the dose fall-off rate can also act as a measuring index for plan comparison, because a fast dose fall-off rate is often a requirement for radiosurgery in order to minimize the risk of radiation damage to the surrounding structures. The two phantom studies showed consistent results with the theoretical predictions. The ability of the plot was further explored in the patient treatment plan studies. It was demonstrated that the plot had a remarkable ability to check whether the hot spot is in the vicinity of the lesion. A baseline of a conformal plan was also established; for example, a plan is said to be conformal if its IPV has attained a value of not less than 95% and its associated TVR is not greater than 2. CONCLUSION: The proposed method has demonstrated the effectiveness in dose conformity evaluation. It supplements the integral dose-volume histogram to provide a complete information of a treatment plan in terms of dose uniformity and conformity.

The effect of the nasopharyngeal air cavity on x-ray interface doses.

We investigated the impact of air cavities in head and neck cancer patients treated by photon beams based on clinical set-ups. The phantom for investigation was constructed with a cubic air cavity of 4 x 4 x 4 cm3 located at the centre of a 30 x 30 x 16 cm3 solid water slab. The cavity cube was used to resemble an extreme case for the nasal cavity. Apart from measuring the dose profiles and central axis percentage depth dose distribution, the dose values in 0.25 x 0.25 x 0.25 cm3 voxels at regions around the air cavity were obtained by Monte Carlo simulations. A mean dose value was taken over the voxels of interest at each depth for evaluation. Single-field results were added to study parallel opposed field effects. For 10 x 10 cm2 parallel opposed fields at 4, 6 and 8 MV, the mean dose at regions near the lateral interfaces of the cavity cube were decreased by 1 to 2% due to the lack of lateral scatter, while the mean dose near the proximal and distal interfaces was increased by 2 to 4% due to the greater transmission through air. Secondary build-up effects at points immediately beyond the air cavity cube are negligible using field sizes greater than 4 x 4 cm2. For most head and neck treatment, the field sizes are usually 6 x 6 cm2 or greater, and most cavity volumes are smaller than our chosen dimensions. Therefore, the influence of closed air cavities on photon interface doses is not significant in clinical treatment set-ups.

The effect of interruptions and prolonged treatment time in radiotherapy for nasopharyngeal carcinoma.

PURPOSE: The effect of interruptions and prolonged overall treatment time in radiotherapy for nasopharyngeal carcinoma and the significance of timing of interruption was investigated. METHODS AND MATERIALS: Treatment records of 229 patients treated with continuous course (CC) and 567 patients treated with split course (SC) radiotherapy for nonmetastatic NPC were reviewed. Overall treatment time without inclusion of time for boost was calculated. Treatment that extended 1 week beyond scheduled time was considered prolonged. Outcome in patients who completed treatment "per schedule" were compared with those who had "prolonged" treatment. Because of known patient selection bias between CC and SC, patients on the two schedules were analyzed separately. Multivariate analysis was performed for patients on SC. Total number of days of interruption, age, sex, T and N stage, and the use of boost were tested for the whole SC group. Analysis on the effect of timing of interruption was performed in a subgroup of 223 patients on SC who had a single unplanned interruption. Timing of interruption, either before or after the fourth week for the unplanned interruption, was tested in addition to the other variables in multivariate analysis for this subgroup of SC. RESULTS: Twenty-seven (11.8%) patients on CC and 96 (16.9%) patients on SC had prolonged treatment. Patients on SC who had prolonged treatment had significantly poorer loco-regional control rate and disease free survival when compared with those who completed radiotherapy per schedule (p = 0.0063 and 0.001, respectively, with adjustment for stage). For CC, the effect of prolonged treatment on outcome was not significant. The small number of events for patients on CC probably account for the insignificant finding. The number of days of interruption was confirmed as prognostic factor, independent of T and N stages, for loco-regional control and disease-free survival in multivariate analysis for SC. The hazard rate for loco-regional failure increased by 3.3% for each day of interruption. The timing of interruption, at the beginning or towards end of treatment, did not significantly alter outcome. CONCLUSION: Interruptions and prolonged treatment adversely affect outcome in radiotherapy for NPC and the effect of repopulation was confirmed. Every effort should be made to keep treatment on schedule and interruptions for whatever reasons should be minimized.

Volumetric analysis of tumor extent in nasopharyngeal carcinoma and correlation with treatment outcome.

PURPOSE: To investigate the variability of tumor volume in nasopharyngeal carcinoma using quantitative measurements of tumor bulk derived from computed tomography, and to study the prognostic value of tumor volume in comparison with other variables. METHODS AND MATERIALS: Two hundred ninety patients with newly diagnosed nasopharyngeal carcinoma were included in the study. The primary tumor volume (PTV) and nodal tumor volume (NTV) were obtained by outlining the tumor contour followed by summation of areas in sequential pretreatment computed tomography axial scans. Total tumor volume (TTV) was obtained by adding the PTV and NTV. All patients had radiotherapy as the primary treatment, 67 patients also received cisplatin-based neoadjuvant chemotheraphy. RESULTS: A large variation in tumor volume was observed, especially in advanced stage disease. The median PTV (cc) in Ho's T1, T2, and T3 disease were: 6.9 (range: 0.9-42.7), 18.8 (1.6-127.9), and 52.4 (3.3-166.8). The median TTV (cc) in Ho's stage I to IV disease were: 7.6 (range: 1.3-42.7), 19.8 (3.2-55.7), 40.7 (4.1-222.7), and 51.1 (3.1-274.7). Patients with a large PTV (>60 cc) were associated with significantly poorer local control (5-year local control rate: 56%) and disease-specific survival (5-year survival rate: 53%). In patients with a small PTV (< or =20 cc), there were no significant differences in local control among different T stages. Large NTV (>30 cc) was associated with significantly higher distant failure rate (5-year distant relapse-free survival rate: 54%) and lower disease-specific survival (5-year survival rate: 40%). In multivariate analysis, only PTV was found to be an independent factor in predicting local control. CONCLUSION: A large variation of tumor volume was present in different T stage disease of nasopharyngeal carcinoma, and PTV represents an independent prognostic factor of local control that appears to be more predictive than Ho's T stage classification.

Tumor control probability of nasopharyngeal carcinoma: a comparison of different mathematical models.

PURPOSE: Radiation dose and tumor volume are factors known to affect the local control of a given type of tumor. Local tumor control is a major factor to consider when a treatment plan is evaluated. This article reports the correlation between tumor control probability, dose, and volume in a retrospective study of 142 patients with nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: The tumor volume was outlined and calculated from a computed tomographic scan. Patients were categorized according to tumor volume and radiation dose received in treatment. Local control rate was calculated for each category by the Kaplan-Meier method. Mathematical models were fitted to correlate the local control rate, dose, and volume. Both empirical and mechanistic approaches were attempted; the former included logistic models with two and three parameters, and the latter, the formulation from Brenner and Bentzen with a radiobiological basis. RESULTS: Brenner's model estimated alpha at 0.041 Gy(-1) with 95% confidence limits (-0.032, 0.113) Gy(-1). The volume dependent constant h was estimated at 0.160 cm(-3) with 95% confidence limits (-0.729, 1.048) cm(-3). The Pearson correlation coefficient was 0.64. The magnitude and sign of the fitted parameters were reasonable and consistent with reported clinical experience. The other models were fitted with slightly better goodness of fit (r = 0.65 - 0.68), but with less interpretable parameters. CONCLUSION: Brenner's model is considered appropriate for a description of the dose and volume effect on the local control of the NPC. It could be used in combination with normal tissue complication probability for treatment plan evaluation to optimize treatment results.

Sensorineural hearing loss in patients treated for nasopharyngeal carcinoma: a prospective study of the effect of radiation and cisplatin treatment.

PURPOSE: The pattern of sensorineural hearing loss (SNHL) after primary treatment for nasopharyngeal carcinoma (NPC) was studied, and the effect of cisplatin, radiotherapy does, and fractionation were evaluated. METHODS AND MATERIALS: One hundred thirty-two patients, 227 ears, and 1100 audiogram reports were analyzed. Radiotherapy dose ranged from 59.5 to 76.5 Gy. Fifty-two patients received preirradiation cisplatin, total dose 100-185 mg/m(2). Serial postirradiation bone conduction thresholds at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz were compared with pretreatment thresholds at respective frequencies. Increase of at least 15 dB was considered as significant and was further grouped as transient or persistent SNHL. Univariate and multivariate analyses were performed to identify predicting factors for persistent SNHL. RESULTS: At median follow-up of 30 months, 24.2% of ears developed persistent SNHL. High frequency was more affected than low frequencies, 22 vs. 5.3%. Males were more affected than females, 29.4 vs. 15.5%, p = 0.0132. Incidence of persistent SNHL increased with age, with 0, 17.2, and 37.4% of patients aged under 30, between 30-50 and over 50 affected, respectively, p = 0.0001. High incidence was found in patient with postirradiation serous otitis media (SOM), 46.9%. Chemotherapy with cisplatin and radiation dose or fractionation had no significant effect. Multivariate analysis confirmed age, sex, and postirradiation SOM as significant prognostic factors for persistent SNHL. CONCLUSIONS: Transient and persistent SNHL occurred after radiotherapy, more commonly affecting high frequency. A low dose of preirradiation cisplatin did not increase the risk. A dose fractionation effect of radiotherapy was not confirmed in this study.

Prognostic value of paranasopharyngeal extension of nasopharyngeal carcinoma. A significant factor in local control and distant metastasis.

BACKGROUND: This study was conducted to evaluate the prognostic value of paranasopharyngeal extension in local control and distant metastasis in patients with nasopharyngeal carcinoma. METHODS: Three hundred and sixty-four patients with newly diagnosed nasopharyngeal carcinoma without distant metastasis were reviewed. Patients were staged according to Ho's staging system. Using a semiquantitative method, tumor extension into the paranasopharyngeal space was graded as: 0: no extension; 1: extension to the retrostyloid space; 2: extension to the prestyloid space; and 3: extension to the anterior part of the masticator space. All patients received radiotherapy as primary treatment. Median follow-up time was 45 months (range, 4.7 to 76.5 months). Relapse free, local relapse free, and distant metastasis free survival were estimated using the Kaplan-Meier method. Cox regression was also performed to adjust for prognostic factors. RESULTS: The incidence of paranasopharyngeal extension was high (72.5%). Of these patients, 65.5% had Grade 2 or 3 extension. The 5-year relapse free survival rates for Grade 0, 1, 2, and 3 extension were 76%, 70%, 46%, and 43%, respectively. The main difference was between Grade 0/1 and Grade 2/3 extension, the latter having a lower 5-year local control rate (86% in Grade 0/1 vs. 72% in Grade 2/3; P < 0.0001) and distant metastasis free survival rate (87% in Grade 0/1 vs. 68% in Grade 2/3; P = 0.0002). Multivariate analysis showed that Grade 2/3 paranasopharyngeal extension was an independent factor in predicting overall relapse, local relapse, and distant metastasis. Advanced T classification (T3) was another independent factor in predicting overall and local relapse, whereas advanced N classification (N3) was another independent factor in predicting overall relapse and distant metastasis. CONCLUSIONS: Extensive paranasopharyngeal extension (Grade 2/3) was an independent prognostic factor associated with poorer treatment outcome, both in local control and distant metastasis. Ho's T2 disease should be further subclassified into T2a and T2b, which include Grade 0/1 and Grade 2/3 paranasopharyngeal disease, respectively.

Vaginal template implant for cervical carcinoma with vaginal stenosis or inadvertent diagnosis after hysterectomy.

PURPOSE: For cervical carcinoma patients with poor geometry for conventional intracavitary radiotherapy, a simple vaginal template for interstitial implantation as a substitute was used. This template has also been used to treat patients who had hysterectomy done without knowledge of an early tumor in the cervix, and for patients with recurrent disease. This is a report of the treatment results. METHODS AND MATERIAL: A total of 21 patients were treated over from July 1987 to June 1991 with this vaginal template implant forming part of the treatment, 12 of these were performed for vaginal stenosis. The applicator consists of a front piece and an end piece. Holes were drilled in the front piece to guide the implantation of the cervix or vaginal vault. The diameter of applicators varied from 2 cm to 3.5 cm. Depending on the diameter of the applicators, six to eight needles on the periphery, or eight peripheral plus one central needle were used. The activity of the needles were around 8 mCi with a total length of 5.5 cm. The end piece was locked onto the front piece by a bayonet-type locking device. The purpose of the end piece was two-fold: to make up the length of the whole applicator to fit the vagina and to keep the implanted needles in place without being extruded. The implantation was performed under general anesthesia. RESULTS: One of the twelve patients treated with the vaginal template implant for vaginal stenosis had relapsed centrally but subsequently died of intercurrent disease. Two other patients died of intercurrent disease at 26.2 and 41.9 months, respectively, without evidence of relapse. Nine other patients had been followed with no evidence of local relapse for 23.7 to 54.6 months. CONCLUSION: This vaginal template implantation is a satisfactory means of treating patients with vaginal stenosis and those who had hysterectomy done without knowledge of an early tumor in cervix.

Transpalatal insertion of radioactive gold grain for the treatment of persistent and recurrent nasopharyngeal carcinoma.

PURPOSE: To evaluate the efficacy of radioactive gold grain implant via the split palate approach in the control of locally recurrent or persistent nasopharyngeal carcinoma. METHODS AND MATERIAL: Forty-three patients, 10 for persistent NPC, 28 for first relapse in the nasopharynx, and five for second relapse in the nasopharynx, were treated. The diameter of the tumors at the time of gold grain implant ranged from 0.5 to 5 cm, the number of gold grains inserted varied from 4 to 14, the median number was seven. RESULTS: There was no significant difference in the control of the primary tumor for persistent disease (80% at 5 years), first relapse (61% at 5 years) and second relapse (80% at 3 years), p = 0.8845. The difference in survival between the three subgroups of patients, however, was highly significant (p = 0.0040). Thirty patients had CT evaluation before gold grain implant and the tumor was found confined to the nasopharynx in 21, in the remaining nine patients erosion of the sphenoid sinus or other parts of the base of skull was noted. The difference in the control between those patients with tumors confined to the nasopharynx and those patients with extranasopharyngeal extension of tumor almost reached statistical significance (81% and 44% respectively at 5 years, p = 0.0554). For the six patients who developed local recurrence after gold grain implant and were evaluable for the pattern of failure, the recurrent tumors were considered originating from another region of the nasopharynx in four, and in-field failure in the other two cases. CONCLUSION: Radioactive gold grain implant as salvage treatment provides satisfactory control of persistent and recurrent nasopharyngeal carcinoma. The local control was better when the tumor was localized to the nasopharynx, thus underlines the importance of close follow-up for early recognition of relapse and persistent tumor. However, such patients still suffered from high incidence of regional and distant failure, the pathophysiology and management of which require further investigation.

Characterization of a new model of GM2-gangliosidosis (Sandhoff's disease) in Korat cats.

We have detected a disorder in Korat cats (initially imported from Thailand) that is analogous to human Sandhoff's disease. Pedigree analysis indicates that this disease in an autosomal recessive disorder in the American Korat. Postmortem studies on one affected cat showed hepatomegaly that was not reported in the only other known feline model of GM2-gangliosidosis type II. Histologic and ultra-structural evaluation revealed typical storage vacuoles. There was a marked deficiency in the activity of hexosaminidase (HEX) A and B in affected brain and liver as compared to controls. Electrophoresis of a liver extract revealed a deficiency of normal HEX A and B in the affected animals. The blocking primary enzyme immunoassay verified the presence of antigenically reactive HEX present in affected cat livers in quantities slightly elevated with respect to the normal HEX concentration in control cats. In leukocytes, obligate heterozygotes had intermediate levels of total HEX activity with a slight increase in the percent activity due to HEX A. Indeed, 4 of 11 phenotypically normal animals in addition to four obligate heterozygotes appear to be carriers using this assay. Affected brain and liver compared with control brain and liver contained a great excess of bound N-acetylneuraminic acid in the Folch upper-phase solids; thin-layer chromatography showed a marked increase in GM2-ganglioside. In summary, we have characterized the pedigree, pathology, and biochemistry of a new feline model of GM2-gangliosidosis which is similar to but different from the only other known feline model.

Reporting history to an addict registry before and after admission to methadone treatment in Hong Kong.

The likelihood of being reported to an addict registry before and after admission to a methadone treatment program in Hong Kong was determined for all 1,908 patients who enrolled during May and June 1978. In the 6 months before enrollment, two out of every five patients had contact with at least one reporting source, and 10% of all patients had contact with a criminal justice system agency. Cohorts grouped according to retention in treatment did not differ with respect to preadmission reporting experience. Following enrollment, however, these cohorts demonstrated a very strong association between continued treatment and a decreased likelihood of contact with a reporting source: 13% of continuously active patients were reported during the 6 months after enrollment, compared to 68% of those who dropped out of treatment within 2 months; the corresponding reporting history from criminal justice system agencies was 6 and 23%, respectively. The association between retention and decreased contact with reporting agencies was observed for each age group studied. Following discharge, the cumulative likelihood of being reported rapidly approached that of patients leaving treatment earlier.