Dose escalation for non-small cell lung cancer using conformal radiation therapy

PURPOSE

Improved local control of non-small cell lung cancer (NSCLC) may be possible with an increased dose of radiation. Three-dimensional radiation treatment planning (3D RTP) was used to design a radiation therapy (RT) dose escalation trial, where the dose was determined by (a) the effective volume of normal lung irradiated, and (b) the estimated risk of a complication. Preliminary results of this trial were reviewed.

METHODS AND MATERIALS

A graph of the iso-normal tissue complication probability (NTCP) levels associated with a dose and effective volume (V(eff)) was derived, using normal tissue parameters derived from the literature. This led to a dose escalation schema, where patients were sorted into 1 of 5 treatment bins, determined by the V(eff) of the best possible treatment plan. The starting doses ranged from 63 to 84 Gy. Each treatment bin was then escalated separately, as in Phase I dose escalation fashion, with Grade > or = 3 radiation pneumonitis defined as dose limiting. To allow for dose escalation, we required patient follow-up to be > or = 6 months for at least three patients. 3D treatment planning was used to irradiate only the radiographically abnormal areas, with 2.1 Gy (corrected for lung inhomogeneity)/day. Clinically uninvolved lymph nodes were not treated prophylactically.

RESULTS

A total of 48 NSCLC patients have been treated (Stage I/II: 18 patients; Stage III: 28 patients; mediastinal recurrence postsurgery: 2 patients). No radiation pneumonitis has been observed in the 30 patients currently evaluable beyond the 6-month time point. All treatment bins have been escalated at least once. Current doses in the five treatment bins are 69.3, 69.3, 75.6, 84, and 92.4 Gy. None of the 15 evaluable patients in any bin with > or = 30% NTCP experienced clinical radiation pneumonitis, implying that the actual risk is < 20% (beta error rate 5%). Despite the observation of the clinically negative lymph nodes at high risk, there has been no failure in the untreated mediastinum as the sole site of first failure. Three of 10 patients receiving > or = 84 Gy have had biopsy proven residual or locally recurrent disease.

CONCLUSION

Successful dose escalation in a volume-dependent organ can be performed using this technique. By incorporating the effective volume of irradiated tissue, some patients have been treated to a total dose of radiation over 50% higher than traditional doses. The literature-derived parameters appear to overestimate pneumonitis risk with higher volumes. There has been no obvious negative effect due to exclusion of elective lymph node radiation. When completed, this trial will have determined the maximum tolerable dose of RT as a single agent for NSCLC and the appropriate dose for Phase II investigation.

Long-term results of hepatic artery fluorodeoxyuridine and conformal radiation therapy for primary hepatobiliary cancers

PURPOSE

We have previously shown that conformal radiation therapy (RT) combined with hepatic artery (HA) fluorodeoxyuridine (FdUrd) had encouraging hepatic control and survival rates for patients with nondiffuse primary hepatobiliary malignancies. With longer follow-up, we were particularly interested if long-term hepatic control and disease-free survival could be achieved, and if late hepatic complications due to radiation therapy were observed.

METHODS AND MATERIALS

Patients with unresectable primary hepatobiliary cancer were treated with concurrent HA FdUrd (0.2 mg/kg/day) and conformal RT (1.5-1.65 Gy per fraction, twice a day), directed only to the liver abnormalities. Three-dimensional treatment planning was used to define both the target and normal liver volumes. The total dose of radiation (48 or 66 Gy) was determined by the fractional volume of normal liver excluded from the high dose volume. Patients were followed routinely for response, patterns of failure, long-term toxicity, and survival. The median potential follow-up was 54 months.

RESULTS

A total of 22 patients (11 with hepatocellular carcinoma and 11 with cholangiocarcinoma) were treated. There were 10 objective responses in the 11 evaluable patients. The overall freedom from hepatic progression at more than 2 years was about 50%. The median survival was 16 months with an actuarial 4-year survival of about 20%. Gastrointestinal bleeding was the most common long-term toxicity. Late hepatic toxicity was not observed; in fact, hypertrophy of the untreated liver was seen.

CONCLUSIONS

Combined conformal RT and HA FdUrd can produce long-term freedom from hepatic progression and survival in patients with unresectable, nondiffuse primary hepatobiliary malignancies. There were no long-term liver complications observed.

A phase I trial of intravenous bromodeoxyuridine and radiation therapy for pancreatic cancer

PURPOSE

Improved radiosensitization may lead to improved results of treatment for pancreatic cancer. This Phase I trial was designed to determine the maximum tolerable dose of intravenous bromodeoxyuridine (BrdUrd) when given in an alternating weekly fashion with radiation therapy for patients with pancreatic cancer.

METHODS AND MATERIALS

Patients with resected or locally unresectable pancreatic cancer were eligible if distant metastases were not present. A continuous intravenous infusion of BrdUrd was given on weeks 1, 3, 5, and 7. Twice a day radiation therapy (1.5 Gy per fraction) was given on weeks 2, 4, 6, and 8 to the pancreas/pancreatic bed (total dose 60 Gy) and draining regional lymph nodes (total dose 45 Gy). The starting dose of BrdUrd was 800 mg/m2/day with a planned escalation to 1000 mg/m2/day if at least six out of eight patients were without Grade > or = 3 toxicity. Patients were assessed weekly for toxicity, and were followed every 3 months after treatment for complications and survival.

RESULTS

Fifteen patients with resected (six) or unresectable (nine) pancreatic cancer were enrolled. One patient failed to complete therapy due to tumor progression. One of 11 patients treated with 800 mg/m2/day had a Grade 3 toxicity, while Grade 3 or 4 toxicity was found in all 3 patients receiving 1000 mg/m2/day. The dose-limiting toxicities were hematologic. The acute gastrointestinal toxicity was minimal. Two patients, including one with unresectable disease, were without evidence of disease during exploration for complications (ulcer, small bowel obstruction).

CONCLUSIONS

The recommended dose of BrdUrd for Phase II study is 800 mg/m2/day. The gastrointestinal mucosa did not appear to be sensitized by this method of BrdUrd administration. The presence of a pathologic complete response is encouraging. Further improvements in radiosensitization are possible and may lead to improved local control.

Tricuspid valve surgery: 15-year experience

Tricuspid valve surgery has been associated with a high operative mortality. This study reviewed 51 patients who underwent 53 tricuspid valve procedures between 1975 and 1989. Most patients (82%) had evidence of rheumatic heart disease. Twenty-six patients (51%) had 42 previous cardiac operations, most involving the mitral valve. Eighty-two percent of patients were New York Heart Association (NYHA) class III or IV preoperatively, and almost all patients had associated disease of other valves. The indication for operation was tricuspid regurgitation in 45 patients, infectious endocarditis in 4, and tricuspid stenosis in 2. The tricuspid abnormality was functional in 67% and organic in 33%. There were 32 tricuspid valve replacements, 20 annuloplasties, and 1 tricuspid valve excision. The hospital mortality rate was 11.8% (six patients). On statistical analysis, none of the perioperative variables were a significant risk factor for hospital mortality. Twenty-nine patients (51%) had postoperative complications. Postoperative functional status improved markedly with 80% in NYHA class I and 13% in class II. Long-term follow-up was attempted but was unsatisfactory in this transient, indigent population.

Uncertainties in CT-based radiation therapy treatment planning associated with patient breathing

PURPOSE

To evaluate uncertainties associated with treatment-planning computed tomography (CT) data obtained with the patient breathing freely.

METHODS AND MATERIALS

Patients with thoracic or abdominal tumors underwent a standard treatment-planning CT study while breathing quietly and freely, followed by CT scans while holding their breath at normal inhalation and normal exhalation. Identical treatment plans on all three CT data sets for each patient pointed out differences in: (a) radiation path lengths; (b) positions of the organs; (c) physical volumes of the lung, liver, and kidneys; (d) the interpretation of plan evaluation tools such as dose-volume histograms and normal tissue complication probability (NTCP) models; and (e) how well the planning CT data set represented the average of the inhalation and exhalation studies.

RESULTS

Inhalation and exhalation data differ in terms of radiation path length (nearly one quarter of the cases had path-length differences > 1 cm), although the free breathing and average path lengths do not exhibit large differences (0-9 mm). Liver and kidney movements averaged 2 cm, whereas differences between the free breathing and average positions averaged 0.6 cm. The physical volume of the liver between the free breathing and static studies varied by as much as 12%. The NTCP calculations on exhale and inhale studies varied from 3 to 43% for doses that resulted in a 15% NTCP on the free-breathing studies.

CONCLUSION

Free-breathing CT studies may improperly estimate the position and volume of critical structures, and thus may mislead evaluation of plans based on such volume dependent criteria such as dose-volume histograms and NTCP calculations.

A rationale for expanding the endpoints for clinical trials in advanced pancreatic carcinoma

BACKGROUND

Using classical endpoints, such as response rate and survival, as the sole measures of benefit, little progress has been made in the treatment of advanced pancreatic carcinoma in the past 30 years. We challenge the assumption that response rate and survival are the only appropriate endpoints for clinical trials in this disease setting.

METHOD

A review of the literature and roundtable discussion were undertaken.

RESULTS

Using current imaging techniques, it is inherently difficult to distinguish pancreatic tumor from normal pancreas, inflammatory tissue, local fibrosis, and unopacified bowel. As a result, objective tumor measurements are often imprecise, unreliable, and irreproducible. This difficulty may explain the wide variation in response rates reported in clinical trials even when the same therapies are used. Tumor-related symptoms, such as anorexia, weight loss, severe pain (requiring opioid analgesia), and impaired functional status, are prevalent and debilitating characteristics of this disease. Tools that can assess these symptoms in a consistent fashion over time have been developed and have been integrated into clinical trials to evaluate new drugs in this setting.

CONCLUSIONS

Systematic assessment of the impact of a new therapy on tumor-related symptoms may provide a sensitive and accurate way to identify useful new treatments for patients with advanced pancreatic carcinoma. Such analyses can be a useful complement to the classical endpoints of response rate and survival.

Preclinical studies of chemotherapy and radiation therapy for pancreatic carcinoma

The use of radiation therapy combined with 5-fluorouracil (5-FU) in the treatment of pancreatic cancer has been well established. It has been hypothesized that any benefit from combined 5-FU and radiation has been due to radiosensitization. Improved therapy could result from a better understanding of the mechanism of radiosensitization and the development of compounds capable of providing better radiosensitization. This article reviews preclinical findings on the mechanism of cytotoxicity and radiosensitization for 5-FU, fluorodeoxyuridine, thymidine analogs, and gemcitabine (2',2'-difluorodeoxycytidine) and discusses the clinical implications of these findings.

A three-dimensional approach for re-irradiation of recurrent colorectal adenocarcinoma

A large number of patients with resected rectal cancer will develop a symptomatic pelvic recurrence despite previous adjuvant radiation therapy. Re-irradiation after previous high dose radiation therapy carries an increased risk of complications in the normal tissues of the pelvis. However, other treatment modalities are not likely to provide a palliative benefit. Previous studies have shown that re-irradiation may be feasible and may palliate the patient. As minimal data is available on the toxicity of additional radiation therapy, this approach would be considered only when there is no other alternative for effective therapy and in the face of progressive and severe symptoms. With the use of three dimensional (3-D) treatment planning, portals can be designed to limit dose to previously irradiated critical structures while minimizing the risk of treatment related complications.

Delayed tuberculin reactivity in persons of Indochinese origin: implications for preventive therapy

OBJECTIVES

To 1) study a variant delayed reaction to tuberculin testing as a way to enhance screening for tuberculosis among high-risk persons and 2) correlate the delayed reaction with lymphocyte blastogenesis.

DESIGN

Cross-sectional study.

SETTING

2 public health department clinics in North Carolina.

PARTICIPANTS

121 adults who had recently emigrated from Vietnam to North Carolina and who were ethnic Vietnamese and ethnic Dega, a minority population group from the central highlands region of Vietnam.

MEASUREMENTS

Medical history, physical examination, laboratory evaluation, and standard purified protein derivative (PPD) testing (Mantoux method). Skin test results were read at 72 hours and again at 6 days. Variant reactivity was defined as induration of less than 10 mm at 72 hours that, when reassessed at 6 days, had increased in size to 10 mm or greater. Persons with negative (n=54) and variant (n=32) PPD results also had booster testing at 10 to 12 weeks. Serum samples were obtained from 57 participants for lymphocyte blastogenesis studies.

RESULTS

26% of participants had variant tuberculin reactivity. Variant reactivity was strongly associated with booster positivity: Sixty-five percent of persons with variant PPD results had booster positivity compared with 16% of persons with negative PPD results (P<0.001). The lymphocyte blastogenesis response of persons with variant PPD results was between the response of persons with negative PPD results and that of persons with positive PPD results.

CONCLUSION

Variant reactivity in this high-risk group was a predictor of booster positivity. Together with the blastogenic response pattern, this association strongly suggests that variant reactivity has a high positive predictive value for tuberculous infection. Clinicians should incorporate these findings into their approach for choosing candidates for preventive therapy.

Splitting on a pediatric consult liaison service

OBJECTIVE

Although the concepts of splitting and projective identification have been useful in explaining certain group phenomena on adult psychiatric and medical wards, their application to pediatric settings has not been addressed in the literature. The authors demonstrate that early identification, staff conferencing, and family/staff conferencing can diffuse these dynamics in an academic pediatric setting.

METHOD

The existing literature on splitting and projective identification is reviewed. Case vignettes are then used to illustrate the manifestations of splitting and projective identification in a pediatric setting and to demonstrate intervention strategies modified for children and their families from the adult literature.

RESULTS

Splitting and projective identification can be interrupted in pediatric settings with early identification, staff conferencing, and family/staff conferencing. The cooperation of pediatric clinicians is critical in the implementation of these intervention strategies.

CONCLUSIONS

The development of liaison support groups for pediatric residents and interdisciplinary treatment teams will enlist their cooperation in identifying splitting early, and in employing staff conferencing and family/staff conferencing to diffuse this group dynamic which, if left unchecked, can disrupt professional relationships and compromise the treatment of pediatric patients.

Pelvic radiation therapy combined with hepatic artery chemotherapy for resected rectal carcinoma with liver metastases

PURPOSE

Patients with hepatic metastases from rectal cancer treated with hepatic artery (HA) chemotherapy have a life expectancy great enough to be at risk for pelvic failure. Therefore, a treatment plan was developed for patients with resected rectal cancer and unresectable hepatic metastases, when the pathologic features of transmural invasion and perirectal lymph node metastases were present. Treatment consisted of concurrent pelvic radiation therapy (RT) and HA 5-fluorouracil (FUra), as systemic levels of FUra are achievable with HA administration, followed by HA fluorodeoxyuridine (FdUrd).

METHODS AND MATERIALS

Fifteen patients were offered combined pelvic RT and HA FUra. Radiation was given to an initial dose of 45 Gy to the pelvis, followed by boost treatment for an additional 5.4-10.8 Gy. Concurrent HA chemotherapy was given using FUra or FUra/leucovorin administered in two cycles of 14 days for each cycle. If HA chemotherapy could not be done, then intravenous FUra was given during RT. Following completion of RT and HA FUra, patients were evaluated for treatment with HA FdUrd.

RESULTS

Eleven patients received concurrent HA FUra or FUra/leucovorin and pelvic RT. Of these, six continued to receive HA FdUrd after completion of RT, as five patients were found to have progressive hepatic disease. Four patients could not have therapy as outlined, but did receive pelvic RT with concurrent intravenous FUra (two patients), FUra/leucovorin (one patient), or sequential HA FUra (one patient). There were four pelvic recurrences at 1, 4, 14, and 17 months after RT. One was the first site of progression, two occurred simultaneously with other failure, and one occurred after hepatic progression. The liver was the most frequent site of first progression (alone in seven patients; as a component of progression in four patients). Treatment was well tolerated with three Grade > or = 3 toxicities. The median survival was 14 months.

CONCLUSIONS

These data support the hypothesis that patients with metastatic rectal cancer are also at risk for pelvic recurrence. The frequency of hepatic progression supports continued aggressive therapy directed to this site. As systemic and regional therapy of metastatic rectal cancer improves, we anticipate that more patients will be at risk for a pelvic recurrence, making it increasingly important to explore the role of pelvic radiation therapy despite the presence of metastatic disease.

Incorporation of 5-bromo-2'-deoxyuridine into colorectal liver metastases and liver in patients receiving a 7-day hepatic arterial infusion

Preclinical and clinical data suggest that the combination of hepatic arterial bromodeoxyuridine (BrdUrd), a thymidine analogue radiation sensitizer, and high-dose three-dimensional conformal radiation therapy offer a high potential for improving the local control of intrahepatic cancers. A key step in the design of a successful protocol is to determine in patients the conditions for BrdUrd administration that would be expected to produce selective radiosensitization of the tumor. Therefore, we designed a clinical trial to assess BrdUrd incorporation into the DNA of hepatic colorectal metastases and normal liver after a 7-day continuous BrdUrd infusion at a dose rate of 25 mg/kg/day (the maximal tolerated dose for a 14-day infusion) for patients undergoing laparotomy for either resection of liver metastases or hepatic arterial catheter and pump placement. Thirteen patients were entered into this study. We found that the average replacement of thymidine by BrdUrd in the tumor and normal liver were 11.6 +/- 1.2% and 1.1 +/- 0.2%, respectively. This extent of incorporation would be expected to produce a single fraction radiation enhancement of 1.5 in the tumor without detectable sensitization of the normal liver. Immunohistochemical staining for BrdUrd revealed heterogeneity of incorporation with a range of approximately 60-80% of the cells labeled in different regions of the specimens. These findings suggest that hepatic arterial BrdUrd given at this dose and schedule has a high likelihood of producing clinically significant radiosensitization for patients with hepatic metastases from colorectal cancer. Furthermore, the demonstrated selectivity of tumor perfusion that can be obtained with hepatic arterial infusion combined with the high proliferative rate of colorectal metastases (versus normal liver) suggests that these patients may be good candidates for tumor-directed gene transfer therapy by using regionally delivered retroviral vectors.

Forensic applications of a rapid, sensitive, and precise multiplex off lysis of the four short tandem repeat loci HUMVWF31/A, HUMTH01, HUMF13A1, and HUMFES/FPS

A system of four short tandem repeat loci (HUMVWF31A, HUMTH01, HUMF13A1, and HUMFES/FPS) has been tested in co-amplification with forensic (post-mortem and post-coital) DNA samples. Semiautomated DNA typing was employed to analyze polymerase chain reaction (PCR) products formed by extension of primers labeled with a fluorescent dye at the 5'-terminus. Most DNA extracts could be typed, although a few required the addition of bovine serum albumin or a pretreatment by ultrafiltration in order to obtain sufficient signal for typing. Balanced signals for the alleles were obtained frequently across the loci, although preferential amplifications of HUMTH01 was observed often with the forensic samples. Band splitting due to nontemplate nucleotide addition to the blunt ends of the amplimers was frequently detected for the DNA extracted from the forensic samples. A data-base was constructed for the African-American population and compared with a Caucasian database. Few differences were observed across the two populations, except at the locus HUMTH01. The fluorescence-based system facilitates large-scale databasing, because the PCR products run off the gel, allowing more than one set of samples to be analyzed per run. Polyacrylamide gel reuse did not diminish genotyping accuracy.

Current status of radiation sensitization by fluoropyrimidines

Numerous clinical studies suggest that the combination of the fluoropyridimine fluorouracil and radiation is a more effective treatment for many cancers, especially gastrointestinal tumors, than is either modality alone. Also, the combination of fluorouracil and radiation has greatly expanded the possibilities for organ-preserving treatments, for example, in patients with bladder cancer. Another fluoropyridimine, floxuridine, administered via the hepatic artery, has been used in combination with irradiation in the treatment of patients with intrahepatic cancers and may prolong survival in patients with unresectable hepatobiliary malignancies. The beneficial effects of combining fluoropyrimidines and radiation are thought to be due to radiosensitization. More studies are needed to clarify the mechanism(s) of radiosensitization so as to optimize regimens in which the fluoropyrimidines are used.

High-dose localized radiation therapy for treatment of hepatic malignant tumors: CT findings and their relation to radiation hepatitis

OBJECTIVE

High-dose radiation therapy of the liver performed using overlapping portals defined by a three-dimensional treatment-planning system (conformal radiation therapy) is a new method of treating hepatic tumors. This study was performed to delineate the differences in the CT appearances of the liver after therapy compared with other methods of radiotherapy and to correlate imaging findings to clinical findings of radiation hepatitis.

MATERIALS AND METHODS

Contrast-enhanced CT scans were obtained at 8- to 12-week intervals on 31 consecutive patients with primary or metastatic hepatic malignant tumors. All had undergone high-dose conformal radiation therapy and injection of fluorodeoxyuridine into the hepatic artery as part of the treatment for unresectable hepatic neoplasms. Tumor size, location, presence of changes within the target volume after therapy, presence of atrophy of the treated segments or hypertrophy of the untreated segments, ascites, and any changes in adjacent organs seen on serial CT scans obtained before and after treatment were recorded. Clinical records were reviewed for evidence of radiation hepatitis (nonmalignant ascites evident on physical examination and a twofold elevation of alkaline phosphatase in the anicteric patient).

RESULTS

In 23 (74%) of the 31 patients, follow-up CT studies after treatment showed a low-attenuation area adjacent to the hepatic tumor in the target volume. In two patients with fatty infiltration of the liver, CT showed relative increased density in the treatment portal. A sharp, straight interface was rarely seen at the treatment margin. Maximal effect was seen 2-3 months after completion of therapy and persisted for up to 3 months. Atrophy in the treated segment or lobe was seen in four patients, hypertrophy of the untreated liver was seen in four patients, and both effects were seen in seven patients. Extrahepatic effects included segmental right renal atrophy in three patients and duodenal wall thickening in two patients. Only two patients (6%) in this series had clinical evidence of radiation hepatitis.

CONCLUSION

High-dose localized radiotherapy of the liver results in reversible hypodense regions in the liver parenchyma within the target volume that do not have a sharp interface delineating the radiation portal. This appearance should not be confused with tumor progression or irreversible liver injury. The changes evident on CT scans after therapy are not predictive of radiation hepatitis.

Intraoperative coronary artery dilatation with angioscopic guidance

The use of intraoperative balloon dilatation during coronary artery bypass surgery has been limited due to relatively unpredictable and potentially damaging results. The development of fiberoptic angioscopy permits safe visualization of the interior of coronary arteries and may be a valuable adjunct to intraoperative balloon dilatation. A 56-year-old male underwent four vessel coronary grafting with progressive intraoperative balloon dilatation of a second more distal stenosis of the left anterior descending coronary artery. Angioscopy was used to determine optimal balloon sizing and allowed visualization of associated intimal changes that occurred during the procedure, resulting in a successful outcome for this patient.

The treatment of colorectal liver metastases with conformal radiation therapy and regional chemotherapy

PURPOSE

Whole-liver radiation, with or without chemotherapy, has been of modest benefit in the treatment of unresectable hepatic metastases from colorectal cancer. A Phase I/II study combining escalating doses of conformally planned radiation therapy (RT) with intraarterial hepatic (IAH) fluorodeoxyuridine (FdUrd) was performed.

METHODS AND MATERIALS

Twenty-two patients with unresectable hepatic metastases from colorectal cancer, 14 of whom had progressed after previous chemotherapy (2 with prior IAH FdUrd), were treated with concurrent IAH FdUrd (0.2 mg/kg/day) and conformal hepatic radiation therapy (1.5-1.65 Gy/fraction twice a day). The total dose of radiation given to the tumor (48-72.6 Gy) depended on the fraction of normal liver excluded from the high-dose volume. All patients were assessed for response, toxicity, hepatobiliary relapse, and survival. Median potential follow-up was 42 months.

RESULTS

Eleven of 22 patients demonstrated an objective response, with the remainder showing stable disease. Actuarial freedom from hepatic progression was 25% at 1 years. The most common acute toxicity was mild to moderate nausea and transient liver function test abnormalities. There were three patients with gastrointestinal bleeding (none requiring surgical intervention) after the completion of treatment. Overall median survival was 20 months. The presence of extrahepatic disease was associated with decreased survival (p < 0.01).

CONCLUSIONS

Combined conformal radiation therapy and IAH FdUrd can produce an objective response in 50% of patients with hepatic metastases from colorectal cancer. However, response was not durable, and hepatic progression was frequent. Improvements in hepatic tumor control for patients with metastatic colorectal cancer may require higher doses of conformal radiation and/or improved radiosensitization. In an effort to increase radiosensitization, we have recently initiated a clinical trial combining IAH bromode-oxyuridine, a thymidine analog radiosensitizer, with conformal high dose radiation therapy.

Hepatic toxicity resulting from cancer treatment

Radiation-induced liver disease (RILD), often called radiation hepatitis, is a syndrome characterized by the development of anicteric ascites approximately 2 weeks to 4 months after hepatic irradiation. There has been a renewed interest in hepatic irradiation because of two significant advances in cancer treatment: three dimensional radiation therapy treatment planning and bone marrow transplantation using total body irradiation. RILD resulting from liver radiation can usually be distinguished clinically from that resulting from the preparative regime associated with bone marrow transplantation. However, both syndromes demonstrate the same pathological lesion: veno-occlusive disease. Recent evidence suggests that elevated transforming growth factor beta levels may play a role in the development of veno-occlusive disease. Three dimensional treatment planning offers the potential to determine the radiation dose and volume dependence of RILD, permitting the safe delivery of high doses of radiation to parts of the liver. The chief therapy for RILD is diuretics, although some advocate steroids for severe cases. The characteristics of RILD permit the development of a grading system modeled after the NCI Acute Common Toxicity Criteria, which incorporates standard criteria of hepatic dysfunction.

Analysis of clinical complication data for radiation hepatitis using a parallel architecture model

PURPOSE

The detailed knowledge of dose volume distributions available from the three-dimensional (3D) conformal radiation treatment of tumors in the liver (reported elsewhere) offers new opportunities to quantify the effect of volume on the probability of producing radiation hepatitis. We aim to test a new parallel architecture model of normal tissue complication probability (NTCP) with these data.

METHODS AND MATERIALS

Complication data and dose volume histograms from a total of 93 patients with normal liver function, treated on a prospective protocol with 3D conformal radiation therapy and intraarterial hepatic fluorodeoxyuridine, were analyzed with a new parallel architecture model. Patient treatment fell into six categories differing in doses delivered and volumes irradiated. By modeling the radiosensitivity of liver subunits, we are able to use dose volume histograms to calculate the fraction of the liver damaged in each patient. A complication results if this fraction exceeds the patient's functional reserve. To determine the patient distribution of functional reserves and the subunit radiosensitivity, the maximum likelihood method was used to fit the observed complication data.

RESULTS

The parallel model fit the complication data well, although uncertainties on the functional reserve distribution and subunit radiosensitivity are highly correlated.

CONCLUSION

The observed radiation hepatitis complications show a threshold effect that can be described well with a parallel architecture model. However, additional independent studies are required to better determine the parameters defining the functional reserve distribution and subunit radiosensitivity.

Apical dominance in rhizomes of quackgrass, Elytrigia repens: the effect of auxin, cytokinins, and abscisic acid

Experiments were designed to determine the impact of abscisic acid, indole-3-acetic acid, and cytokinins on dormancy of quackgrass (Elytrigia repens (L.) Nevski) rhizome axillary buds using exogenous hormone treatments and analysis of endogenous hormones. Exogenous hormone treatments were applied in solution or in lanolin paste to 5-node segments of rhizome with an apical tip intact or removed. Abscisic acid inhibited bud growth except at concentrations of 0.5 – 1 μg ∙ mL−1 when it stimulated growth: this appeared to be based on an inhibition of apical dominance rather than a stimulation of bud growth per se. Both indole-3-acetic acid and cytokinins stimulated bud growth, indole-3-acetic acid at concentrations of 0.5 – 5 μg ∙ mL−1 and cytokinins at higher concentrations (i.e., 10 – 100 μg ∙ mL−1). Indole-3-acetic acid also increased elongation of the buds, whereas abscisic acid and cytokinins did not. Levels of endogenous hormones were measured in bud samples: indole-3-acetic acid was quantified as its methyl ester by combined gas chromatography – mass spectrometry – selected ion monitoring; abscisic acid was quantified as its methyl ester by gas chromatography – electron capture; and cytokinins were quantified using a soybean callus bioassay. Hormone levels were generally higher in the most active buds of a 5-node section. Abscisic acid was also measured in buds 24 h after sheath leaf removal, a practice known to promote bud sprouting. Sheath leaf removal had no significant effect on abscisic acid levels. Key words: quackgrass, Elytrigia repens, auxins, abscisic acid, cytokinins, apical dominance.

Integrated myocardial management: background and initial application

This report describes the technique of integrated myocardial management, which combines the advantages of various cardioprotective strategies to compensate for their individual shortcomings. This approach coordinates the myocardial protective techniques with the continuity of the operation so that the surgical procedure is never interrupted. This method (1) provides unimpaired vision, (2) avoids unnecessary ischemia and cardioplegic overdose, (3) allows aortic clamping as soon as cardiopulmonary bypass is started, (4) permits aortic unclamping and discontinuation of bypass shortly after the technical procedure is completed, (5) minimizes the duration of ischemia and cardiopulmonary bypass, and (6) maximizes the positive attributes of the strategies available currently. The background for this myocardial management method, which combines antegrade/retrograde delivery, warm/cold blood cardioplegia, intermittent/continuous perfusion, blood/blood cardioplegia, and avoidance of cardioplegic overdose, hemodilution, and tangential aortic clamping, is discussed. The preliminary results in 1474 patients from four centers where surgeons participated in the infrastructure of this method are presented. This has led to our adoption of this approach in all adult cardiac operations.

Preoperative radiation therapy and iododeoxyuridine for large retroperitoneal sarcomas

PURPOSE

Local failure is frequent after conventional therapy for patients with retroperitoneal sarcomas. A Phase I/II multimodality approach was used, combining iododeoxyuridine (IdUrd) and radiation therapy, followed by attempted surgical resection, with the goal of improving local control.

METHODS AND MATERIALS

Patients with retroperitoneal sarcomas were treated with three to five consecutive cycles of treatment. Each 14-day cycle consisted of a continuous intravenous infusion of IdUrd on days 1-5, twice a day radiation therapy (1.25 Gy/fraction) on days 8-12, and a break on day 13 and 14. Surgical resection was attempted after three or five cycles. Patients resected after three cycles received an additional two cycles of treatment with radiation directed to the tumor bed. IdUrd dose was escalated in Phase I fashion (1000 mg/m2/day, 1333 mg/m2/day, and 1600 mg/m2/day). The median potential follow-up was 31 months.

RESULTS

Sixteen patients (13 with high grade tumors) were treated. The median maximum tumor size was 17 cm. Resection margins were negative in four patients, microscopically positive in four patients, and grossly positive in three patients. Five patients were not resected. The only grade 4 acute toxicity observed was vomiting which occurred in three patients receiving upper abdominal radiation. Postsurgical and long-term complications were rare. Median survival overall and for resected patients were 18 and 32 months, respectively. Local control was observed in three out of four patients with negative margins (9, 40+, and 51+ months), two out of four patients with microscopically positive margins (4 and 22 months), and one out of three patients with grossly positive margins (46+ months). The overall freedom from local progression was 45% at 24 months.

CONCLUSION

Retroperitoneal sarcomas can be resected after preoperative radiation therapy and IdUrd, with encouraging local control in patients resected with negative or microscopically positive margins. The recommended dose using this drug and radiation schedule appears to be 1600 mg/m2/day, which will form the basis for a Phase II trial.

Microbiological characterization of the biological treatment of aircraft paint stripping wastewater

Research on the treatment of potentially toxic wastewater produced at six US Navy aircraft paint stripping facilities has been conducted. The composition of the wastewater treated consisted of methylene chloride and phenol in concentrations of about 5000 and 1800 mg/l, respectively, and other organic compounds in a total concentration of 2200 mg/l. Biological treatment is an important means by which toxic or hazardous organic compounds can be economically converted to less noxious materials. Engineering studies conducted in the laboratory with activated sludge reactors and rotating biological contactors (RBC) demonstrated that both suspended and attached growths can be effective biological methods to treat this paint stripping wastewater when blended with domestic wastewater up to about 50% by volume. These studies were complemented with analyses of the bacterial communities inhabiting the treatment systems. The number and the genera of the microorganisms present in the blended wastewater, as well as their ability to biodegrade the potentially toxic organics were studied. The results indicate that paint stripping wastewater is able to support large bacterial populations consisting of various gram-negative rods and coccibacilli and a few gram-positive bacilli. Members of the genera Pseudomonas and Bacillus are suspected to play an important role in initiating the biodegradation process.

An investigation of the association between exposure to styrene and hearing loss

The importance of the association between advancing age and hearing loss is well recognized. Further, prolonged significant noise exposures are also known to result in permanent hearing loss. However, little is known of the contribution of industrial chemical exposures to hearing loss. Information available, from both animal and human studies, raises the possibility that certain aromatic hydrocarbons are ototoxic. The purpose of this study was to assess whether occupational styrene exposure causes hearing loss in a group of workers in the fiber-reinforced plastics manufacturing industry. The hearing acuity of 299 subjects was determined, using pure-tone screening audiometry, at the beginning of a single workshift and again at the end of the shift. On the same day, the personal, time-weighted average exposures of each subject to both styrene and noise were measured. In addition, information on the following factors was obtained from each participant: previous work history, including exposures to noise and chemicals; use of personal protective equipment for noise or solvents; personal and family history of hearing problems; and smoking history. Current exposures together with work histories were used to construct lifetime noise and styrene exposure indices. No conclusive evidence was found for a chronic styrene-induced effect on hearing acuity, when both noise and styrene lifetime exposures were taken into account. As expected, age and noise exposures were highly important variables, both positively associated with hearing loss. In addition, the detrimental effect of noise exposure on hearing acuity was found to be strengthened with increased age. Noise and styrene exposures were highly correlated, clearly illustrating the importance of considering all associated variables in analysis of such data. No evidence was found for a relationship between smoking, recreational noise, solvent exposures, and hearing loss.

The reduction in alcohol intake produced by enalapril is not attenuated by centrally administered angiotensin inhibitors

Angiotensin-converting enzyme (ACE) inhibitors, which prevent the conversion of angiotensin I to angiotensin II, reduce alcohol intake when injected peripherally. The mechanism by which ACE inhibitors produce this effect on alcohol intake is unknown. A rise in the biosynthesis of angiotensin II in the periphery is known to reduce alcohol intake. In this experiment, we examine the possibility that the reduction in alcohol intake produced by an ACE inhibitor, enalapril, is mediated by a rise in angiotensin II in the brain. Enalapril, 20 mg/kg, injected intraperitoneally, produced a 40% reduction in alcohol intake. This reduction was not attenuated by the concurrent administration into the lateral ventricle of either the ACE inhibitors captopril or ceranapril (1, 10, or 25 micrograms), or the angiotensin II receptor antagonist Sar1-Thr8-Angiotensin II (5 micrograms). These findings suggest that the ACE inhibitors do not reduce alcohol intake by raising angiotensin II in the brain.

Adrenalectomy does not modify the suppressive effect of angiotensin II on voluntary ethanol drinking in rats

Enhancement of activity in the renin-angiotensin system reduces voluntary ethanol consumption in rats. Because angiotensin II, which is a major bioactive component of the renin-angiotensin system, stimulates the release of aldosterone, aldosterone may play a role in the reduction of ethanol intake by angiotensin II. The present study examined ethanol drinking in a group of rats that was bilaterally adrenalectomized and incapable of producing aldosterone, and in a sham group that underwent similar surgery except that the adrenal glands were left intact. Rats were maintained on ad libitum food, water and 1.5% saline solution in their home cages. Access to ethanol (6% weight/volume) was restricted to a daily 40 min period and was always offered as a choice in conjunction with water. Adrenalectomy did not alter the effect of angiotensin II on ethanol intake as subcutaneous injections of angiotensin II (400 micrograms/kg) significantly reduced ethanol intake to the same degree in both the adrenalectomized and sham groups. In the next phase, daily subcutaneous injections of aldosterone (100 micrograms/kg) reduced the home cage intake of 1.5% saline in the adrenalectomized group indicating that this dose of aldosterone was biologically active. These aldosterone injections did not affect ethanol intake in either the adrenalectomized or sham groups. Under the present conditions of testing aldosterone does not appear to play a role in the angiotensin II-induced reduction of ethanol consumption.

Simplified method for three-dimensional evaluation of interstitial brachytherapy applications

Although three-dimensional (3-D) treatment planning has primarily been used for external beam radiation therapy, the advantages of 3-D treatment planning can be realized for brachytherapy applications. As with teletherapy, the use of 3-D treatment planning for brachytherapy can provide both superior dose distribution as well as detailed evaluations of the relationship of dose and volume in critical structures and target tissues. Conventional 3-D treatment planning uses computed tomography (CT) scans to localize structures; however, localizing individual brachytherapy sources on each CT slice can be impractical for routine clinical use. In the transition from two-dimensional to 3-D localization and dose evaluation of interstitial perineal templates in particular, a practical method of seed localization on a postimplant CT dataset has been developed. This method does not utilize dummy sources and, as such, does not require individual seed locations to be identified. Instead, the position of the afterloading catheter is defined as a reference line by connecting its location as seen on the axial CT slices and seed locations defined along its length. Full volumetric calculations can then be performed, including dose-volume histograms (DVH) for critical organs and tumor volumes. Source localization and normal tissue doses were calculated using both orthogonal films and the 3-D method for a series of perineal template guided implants. Point dose calculations of the rectum and bladder were obtained from orthogonal films and were then compared to the corresponding DVHs for these organs.

Duchenne/Becker muscular dystrophy carrier detection using quantitative PCR and fluorescence-based strategies

Dystrophin gene deletions account for up to 68% of all Duchenne (DMD) and Becker (BMD) muscular dystrophy mutations. In affected males, these deletions can be detected easily using multiplex PCR tests which monitor for exon presence. In addition, quantitative dosage screening can discriminate female carriers. We previously analyzed multiplex PCR products by gel electrophoresis and quantitation of fluorescently labeled primers with the Gene Scanner in order to test carrier status. These multiplex PCR protocols detect DMD gene deletions adequately, but require up to 18 pairs of fluorochrome-labeled primers. We previously described two alternative fluorescent labeling strategies, each with approximately 1,000-fold greater sensitivity than ethidium bromide staining, which can be used to quantify the products of multiplex PCR. The first method uses the DNA intercalating thiazole orange dye TOTO-1 to stain PCR products after 20 cycles. In the second method, fluorescein-12,2'-dUTP is incorporated into products during PCR as a fluorescent tag for subsequent quantitative dosage studies. Both methods label all multiplexed exons including the 506 bp exon 48 fragment that is difficult to detect and quantify by standard ethidium bromide staining. Using this approach, we determined DMD/BMD carrier status in 24 unrelated families using a fluorescent fragment analyzer. Analysis of fluorochrome-labeled PCR products facilitates quantitative multiplex PCR for gene-dosage analysis.

Bradykinin suppresses alcohol intake and plays a role in the suppression produced by an ACE inhibitor

The possible role of the endogenous kinins in the control of alcohol intake was assessed in two experiments. In Experiment 1, naive rats, maintained on ad lib food and water, were given daily 40-min access to a 6% (w/v) alcohol solution and water. Daily intraperitoneal (IP) injections of captopril (20 mg/kg) significantly reduced alcohol intake, while pretreatment with subcutaneous (SC) injections of the bradykinin antagonist [D-Phe7]-bradykinin (100-300 micrograms/kg) attenuated the suppressive effect of captopril on alcohol intake. The saline vehicle or the bradykinin antagonist alone did not alter alcohol intake. In Experiment 2, bradykinin was administered daily at 100, 200, and 400 micrograms/kg doses SC either alone or in combination with captopril 10 mg/kg IP. Neither bradykinin nor captopril by themselves changed alcohol or water intake. Bradykinin combined with captopril stimulated water intake and reduced alcohol intake by up to 70%. This effect was not due to drug-induced changes in the pharmacokinetics of alcohol. The angiotensin II receptor antagonist [Sar1,Thr8]-angiotensin II at 250 and 500 micrograms/kg SC attenuated the stimulation of water intake but not the reduction in alcohol intake. It is suggested that by inhibiting kininase II, ACE inhibitors extend the duration of action of bradykinin and thereby unmask a potent inhibition of alcohol intake mediated by kinins--an effect that is dissociable from the accompanying stimulation of water intake. Taken together, these results point to an involvement of the kinin system in the regulation of alcohol intake and in particular to a role of bradykinin in the suppressive effect of ACE inhibitors on alcohol intake.

Inhibition of intra-abdominal adhesions: fibrin glue in a long term model

Fibrin glue is being used more frequently to assist in the control of surgical bleeding in the abdominal and thoracic cavities. Prior investigation at this institution has indicated that fibrin glue actually inhibits adhesion formation in the peritoneal cavity of rats up to the first week postoperatively. To ascertain whether this protective effect is borne out in the long term, a randomized study was performed in 42 rats. As in the initial study, bilateral circular peritoneal-muscular defects were created to induce adhesion formation. The right-sided defects were closed linearly with interrupted sutures, thus closing the peritoneum, and the left-sided defects were closed with a continuous suture placed circumferentially, leaving the peritoneal defect open. The rats were randomized to two groups. In 21 animals, the abdomen was closed with no further treatment. In the other 21 animals the defects were covered with fibrin glue made from 0.2 mL of human fibrinogen (31.5 g/L) from cryoprecipitate and 0.2 mL of bovine thrombin and calcium. All rats were killed at 30 days, and adhesions were graded on a scale of 0 to 4 by a blinded observer. In the control group, 15 of 21 rats had high grade adhesions to the closed defect compared with 3 of 21 in the experimental (fibrin glue) group (P = 0.0003). For the left-sided lesions, 16 of 21 animals in the control group had high grade adhesions compared with 2 of 21 animals in the experimental group (P = 0.0004).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of Veff and iso-NTCP in the implementation of dose escalation protocols

PURPOSE

This report investigates the use of a normal tissue complication probability (NTCP) model, 3-D dose distributions, and a dose volume histogram reduction scheme in the design and implementation of dose escalation protocols for irradiation of sites that are primarily limited by the dose to a normal tissue which exhibits a strong volume effect (e.g., lung, liver).

METHODS AND MATERIALS

Plots containing iso-NTCP contours are generated as a function of dose and partial volume using a parameterization of a NTCP description. Single step dose volume histograms are generated from 3-D dose distributions using the effective-volume (Veff) reduction scheme. In this scheme, the value of Veff for each dose volume histogram is independent of dose units (Gy, %). Thus, relative dose distributions (%) may be used to segregate patients by Veff into bins containing different ranges of Veff values before the assignment of prescription doses (Gy). The doses for each bin of Veff values can then be independently escalated between estimated complication levels (iso-NTCP contours).

RESULTS AND CONCLUSION

Given that for the site under study, an investigator believes that the NTCP parameterization and the Veff methodology at least describe the general trend of clinical expectations, the concepts discussed allow the use of patient specific 3-D dose/volume information in the design and implementation of dose escalation studies. The result is a scheme with which useful prospective tolerance data may be systematically obtained for testing the different NTCP parameterizations and models.

Captopril and hydrochlorothiazide (Capozide) combine to enhance the reduction in voluntary alcohol intake in rats

The effect of Capozide, the combination of captopril with a hydrochlorothiazide diuretic, on voluntary alcohol intake was assessed in two experiments. In experiment 1 naive rats who were maintained on ad libitum food and water were given daily 40-min access to a 6% (w/v) alcohol solution and water. Daily intraperitoneal injections of captopril (10 mg/kg) reduced alcohol intake, but the combination of captopril (5 and 10 mg/kg) and hydrochlorothiazide (2.5, 5, and 10 mg/kg) enhanced the reduction in intake. In experiment 2, captopril alone, hydrochlorothiazide alone, and the combination of captopril and hydrochlorothiazide were again administered daily in the limited access procedure. Captopril (10 mg/kg) again reduced alcohol intake as did all three doses of hydrochlorothiazide (2.5, 5, and 10 mg/kg). Compared with the individual effects of captopril and hydrochlorothiazide, Capozide exerted a supra-additive reduction in alcohol intake. These effects were not due to drug-induced changes in the pharmacokinetics of alcohol. Taken together these results demonstrate an enhanced potency of Capozide in suppressing alcohol intake and invite their testing in a population of hypertensive alcoholics and alcohol abusers.

Conformal high-dose radiation plus intraarterial floxuridine for hepatic cancer

The role of traditional whole liver irradiation in the treatment of unresectable intrahepatic cancers has been limited by low liver tolerance. The development of three-dimensional (3D) conformal radiation treatment planning offers the potential to treat tumor-bearing portions of the liver to a far higher dose than the entire liver could tolerate, while sparing uninvolved liver. This concept resembles that used by the surgeon, who determines resectability based on the function of the liver anticipated to remain after resection. We have treated patients with unresectable intrahepatic cancers by combining 3D conformal irradiation with intraarterial hepatic floxuridine, which our laboratory studies show is a radiation sensitizer. We have delivered more than 70 Gy to parts of the liver without producing significant radiation hepatitis. Furthermore, the median survivals of patients with primary hepatobiliary cancer (19 months) and colorectal cancer metastatic to the liver (22 months) approach those achieved by surgical excision in a more favorable group of patients.

An analysis of blood lead data in clinical records by external data on lead pipes and age of household

This study examined the possibility that lead pipes in the drinking water distribution system were elevating the blood lead levels of children in London, Ontario, Canada. Based on their postal codes, 164 children admitted between 1984 and 1989 to an institution for the behaviorally disordered or developmentally challenged were categorized according to whether they lived in the area of the city known by the local Public Utilities Commission to be serviced by lead pipes. Analysis of covariance was used to obtain confounder-adjusted geometric means in each area. After adjusting for gender, year of lead test (a surrogate for gasoline source), and census tract prevalence of low family income, children in the lead service area (LSA) were found not to have higher blood lead levels (geometric means: LSA = 4.7 micrograms/dl, Non-LSA = 4.8 micrograms/dL; p = 0.839). The average blood lead level declined 60.9% between 1984 and 1989. Using municipal tax assessment data on the age of each child's home, those children living in homes built during or before 1945 (when interior paints were as much as 50% lead by dry weight) had an average blood lead level that was 62.3% higher (p = 0.011) than that of those in homes built since 1975 (when interior paints were limited to no higher than 0.5% lead by dry weight). A clear gradient was observed. This association with age of home remained significant after adjusting for gender, diagnosis, and year of lead test. Variables indicating the amount of industry near the child's residence and the presence of lead service pipes did not enter the model after house-age. In conclusion, no evidence indicated that the lead service pipes were elevating blood lead levels in these London children. The data suggest that with the removal of lead from gasoline, lead-based paint is a significant remaining source of lead exposure. Little data are available on childhood lead exposure from paint in Canada. The present descriptive data suggest that more research into this potential problem in Canada is warranted.

Treatment of primary hepatobiliary cancers with conformal radiation therapy and regional chemotherapy

PURPOSE

To develop more effective regional therapy for patients with unresectable primary hepatobiliary cancer using concurrent conformal radiation therapy and intraarterial hepatic (IAH) fluorodeoxyuridine (FdUrd).

PATIENTS AND METHODS

Twenty-six patients with unresectable, nonmetastatic primary hepatobiliary cancer were treated with concurrent IAH FdUrd (0.2 mg/kg/d) and conformal hepatic radiation therapy (1.5 to 1.65 Gy per fraction twice per day). The total dose of radiation administered to the tumor depended on the fraction of normal liver excluded from the high-dose volume. All patients were assessed for toxicity, hepatobiliary relapse, and survival; 17 patients were assessable for response (eight had cholangiocarcinoma not assessable by computed tomographic [CT] scan and one progressed distantly during treatment). The median potential follow-up duration was 27 months.

RESULTS

Whole-liver radiation was administered to six patients with diffuse hepatocellular carcinoma (HCC). Eleven patients with localized HCC and nine with cholangiocarcinoma received focal radiation to a dose of 48 to 72.6 Gy. An objective response for assessable patients was observed in 11 of 11 patients treated with focal radiation, but only one of six patients treated with whole-liver radiation. Whole-liver radiation accounted for five of seven patients with > or = grade 3 toxicity and four of six local treatment failures. Two patients had nonfatal radiation hepatitis. The median survival duration for patients with localized hepatobiliary cancer was 19 months, while patients with diffuse HCC had a median survival duration of 4 months. The rate of actuarial freedom from hepatobiliary progression in patients with localized disease was 72% at 24 months.

CONCLUSION

These findings suggest that three-dimensional planned focal liver radiation and IAH FdUrd can produce a high, durable response rate and an encouraging median survival duration in patients with nondiffuse, unresectable primary hepatobiliary cancer.

Modeling mortality in the intensive care unit: comparing the performance of a back-propagation, associative-learning neural network with multivariate logistic regression

The objective of this study was to compare and contrast two techniques of modeling mortality in a 30 bed multi-disciplinary ICU; neural networks and logistic regression. Fifteen physiological variables were recorded on day 3 for 422 consecutive patients whose duration of stay was over 72 hours. Two separate models were built using each technique. First, logistic and neural network models were constructed on the complete 422 patient dataset and discrimination was compared. Second, the database was randomly divided into a 284 patient developmental dataset and a 138 patient validation dataset. The developmental dataset was used to construct logistic and neural net models and the predictive power of these models was verified on the validation dataset. On the complete dataset, the neural network clearly outperformed the logistic model (sensitivity and specificity of 1 and .997 vs. .525 and .966, area under ROC curve .9993 vs. .9259), while both performed equally well on the validation dataset (area under ROC of .82). The excellent performance of the neural net on the complete dataset reveals that the problem is classifiable. Since our dataset only contained 40 mortality events, it is highly likely that the validation dataset was not representative of the developmental dataset, which led to a decreased predictive performance by both the neural net and the logistic regression models. Theoretically, given an extensive dataset, the neural network should be able to perform mortality prediction with a sensitivity and a specificity approaching 95%. Clinically, this would be an extremely important achievement.(ABSTRACT TRUNCATED AT 250 WORDS)

Glomus tumour of the palate: case report and review of the literature

Glomus tumours are benign vascular tumours, usually located in the skin. Intra-oral glomus tumours are rare. A glomus tumour of the palate is reported, only the fifth such case out of a total of 14 intra-oral glomus tumours in the world medical literature.

Discriminative stimulus properties of substituted amphetamine derivatives

Animals were trained to discriminate amphetamine (1 mg/kg) from saline in a fixed-ratio (FR 10), food-reinforced paradigm. Amphetamine-appropriate responding was engendered by the training dose, and by 3 mg/kg, while at lower doses there was a progressive decrease in the extent of responding on the drug-appropriate lever. The following three novel amphetamine derivatives were tested for their ability to produce amphetamine-appropriate responding: 2,5-dimethoxy-4-ethoxy-amphetamine (DMEA); 2,5-dimethoxy-4-methylthio-amphetamine (DMMTA), and 2,4,5-trimethoxy-amphetamine (TMA). DMEA produced only minimal (< 20%) amphetamine-appropriate responding over a dose range of 0.1-10 mg/kg. Substantial decreases in response rate limited testing of the other amphetamines to a dose maximum of 3 mg/kg, but over the range of 0.1-3.0 mg/kg there was little evidence for generalization. At 3 mg/kg of either DMMTA or TMA, only 2 of 10 animals completed at least one uninterrupted FR 10 on either lever, and with either compound only 1 of these 2 animals responded more than 50% on the drug-appropriate lever. Of the three compounds tested, DMMTA had the greatest response rate-decreasing effect.

Fluorescence-based, multiplex allele-specific PCR (MASPCR) detection of the delta F508 deletion in the cystic fibrosis transmembrane conductance regulator (CFTR) gene

Cystic fibrosis (CF) is a common genetic disorder in Caucasians, and in some populations 70% of cases are associated with a 3 base pair (bp) deletion (delta F508) in the CFTR gene. We have implemented a fluorescence-based, multiplex allele-specific polymerase chain reaction (MASPCR) assay for deletion of the delta F508 mutation. Different allele-specific fluorescently-tagged primers are used in the PCR reaction to distinguish between normal and delta F508 alleles. Fluorescent PCR products are then visualized in a single lane on an agarose gel following electrophoresis combined with real-time multicolour fluorescence detection. The approach simplifies diagnosis of the most common mutation in the CFTR gene, and holds promise for a multiplex allele-specific, fluorescence-tagged gene amplification strategy for detection of additional CF mutations which may result in more cost-effective testing without increasing the risk of missed or erroneous diagnoses.

Automated DNA profiling by fluorescent labeling of PCR products

DNA profiling has been automated by the fluorescent tagging of amplified variable number tandem repeat (VNTR) loci. This was achieved by the use of fluorescently labeled primers in the amplification of 10 ng of genomic DNA, coupled with laser detection of the products during electrophoresis. The PCR products are sized by co-electrophoresing a standard size ladder mixed with every sample, thereby eliminating errors in size estimation caused by lane-to-lane differences in migration rate. This increases the precision of VNTR characterization and enables alleles that differ by a single 15-bp repeat to be resolved. The system is capable of high throughput: Twenty-four samples are electrophoresed and analyzed within 6 hr. Also, because four different dyes are available, three different loci can be simultaneously characterized with the fourth dye used for the internal standard. Approximately 100 unrelated British caucasians were analyzed at the loci D1S80, D17S5, and ApoB. The probabilities of two unrelated individuals matching by chance (pM) at these three loci were determined to be 0.065, 0.040, and 0.069, respectively, with a combined pM of 1.8 x 10(-4).

The clinical application of a non-axial treatment plan for pancreatic and biliary malignancies

Standard radiation therapy for adenocarcinoma of the pancreas treats a substantial portion of the renal parenchyma. It was hypothesized that rotating the plane of treatment to a non-axial orientation, with the anterior field entering the patient from an inferior oblique direction, would decrease the renal dose of radiation without increasing the liver dose or compromising the target dose. To test this hypothesis, patients referred for radical radiation treatment for tumors of the pancreas or distal common bile duct were prospectively evaluated by performing treatment planning using axial and non-axial field arrangements. Treatment plans were compared using dose volume histograms (DVHs) of both kidneys and the liver. In all 15 cases analyzed, the non-axial plan was superior to the axial plan with respect to renal dose, without significantly increasing the hepatic dose and was used for treatment. Treatment was not significantly more complex nor was gastrointestinal toxicity increased. These findings show that non-axial field arrangements can be used on a routine basis to decrease the renal dose of radiation for the treatment of pancreatic and biliary malignancies. It is anticipated that in the future, a combination of DVH-guided treatment planning and sophisticated renal function studies will be necessary to permit a more accurate prediction of the probability of renal complications resulting from radiation therapy.

The use of 3-D dose volume analysis to predict radiation hepatitis

Although it is well known that the tolerance of the liver to external beam irradiation depends on the volume of liver irradiated, few data exist which quantify this dependence. Therefore, a review was carried out of our clinical trial for the treatment of intrahepatic malignancies in which the dose of radiation delivered depended on the volume of normal liver treated. Three dimensional treatment planning using dose-volume histogram analysis of the normal liver was used for all patients. Nine of the 79 patients treated developed clinical radiation hepatitis. None of the patient related variables assessed were associated with radiation hepatitis. All patients who developed radiation hepatitis received whole liver irradiation, as all or part of their treatment, which produced a mean dose greater than or equal to 37 Gy. Dose volume histograms were used to calculate normal tissue complication probabilities based on parameters derived from the literature. The risk of complication was greatly overestimated among patients receiving a high dose of radiation to part of the liver without whole liver treatment. An estimation of model parameters based on the clinical results indicated a larger magnitude for the "volume effect parameter" than the literature estimate (n = 0.69 +/- 0.05 vs 0.32; p less than 0.001). Computation of the normal tissue complication probabilities using the larger value of n produced a good description of the observed risk of radiation hepatitis. These findings suggest that dose volume histogram analysis can be used to quantify the tolerance of the liver to radiation. The predictive value of this parameterization of the normal tissue complication probability model will need to be tested with liver tolerance and dose volume histogram data from an independent clinical trial.

The reinforcing and discriminative stimulus properties of para-ethoxy- and para-methoxyamphetamine

The purpose of this study was two-fold: 1) to assess the degree to which para-methoxyamphetamine and para-ethoxyamphetamine maintain self-administration behavior, and 2) to determine the similarity or difference between these drugs and amphetamine in drug discrimination tests. Animals were trained to self-administer 0.3 mg/kg/infusion cocaine on a fixed-ratio 5 (FR5) schedule of reinforcement. Substitution of para-ethoxyamphetamine (PEA), para-methoxyamphetamine (PMA), or saline produced similar results; in all cases responding decreased substantially. A separate group of animals was trained to discriminate amphetamine (1 mg/kg) from saline in a fixed-ratio (FR10), food-reinforced paradigm. PEA and PMA produced only limited responding on the amphetamine-appropriate lever (maximum of approximately 30%). Both PMA and PEA had effects on response rate which were similar to those of amphetamine, although PMA had slightly greater rate-decreasing effects than the other two compounds. These data suggest that neither PMA nor PEA are reinforcing in rats, and do not possess amphetamine-like discriminative properties.

Effect of right atrial appendectomy on the release of atrial natriuretic hormone

Atrial natriuretic hormone is released from the right atrial appendage in response to atrial distention. During cardiac operations the right atrial appendage is usually partially removed or ligated for venous cannulation. To evaluate the effect of right atrial appendectomy on the release of atrial natriuretic hormone and its natriuretic and diuretic responses, we prospectively randomized into two groups 23 patients undergoing elective coronary artery bypass operations. There were 16 male and 7 female patients with a mean age of 62 +/- 7 years. Group A (n = 11) had the right atrial appendage removed, and group B (n = 12) had the right atrial appendage preserved and venous cannulation done lateral to the appendage. The two groups were comparable for sexual distribution, age, number of grafts, and extracorporeal bypass time. All patients had normal left ventricular and renal functions, and they did not receive any diuretics during the study period. The patients were studied both preoperatively and postoperatively whereby the atrial natriuretic hormone serum levels, urine volume per minute, fractional excretion of sodium, amount of sodium excreted, and central venous pressure were measured before and after volume expansion with 5% albumin, 7.5 ml/kg. There was no statistical difference in these parameters preoperatively. In the postoperative period, however, group B patients had higher atrial natriuretic hormone levels after volume expansion than group A patients (376 +/- 84 versus 184 +/- 31 pg/ml; p less than 0.05), higher urine volume per minute (4.4 +/- 1.0 versus 2.0 +/- 0.4 ml/min; p less than 0.05), higher fractional excretion of sodium (2.30 +/- 0.66 versus 0.64 +/- 0.19; p less than 0.02), and higher amount of sodium excreted (511.1 +/- 150.9 versus 83.9 +/- 22.8 mmol/min; p less than 0.02). The central venous pressure was similar both before (9 +/- 1 versus 9 +/- 1 mm Hg) and after (16 +/- 1 versus 15 +/- 1 mm Hg) volume expansion in both groups. We conclude that preserving the right atrial appendage during cardiac operations significantly increased the release of atrial natriuretic hormone, resulting in increased urinary sodium excretion and better diuresis in the postoperative period.

Breast conservation therapy. Severe breast fibrosis after radiation therapy in patients with collagen vascular disease

Two patients with collagen vascular disease (rheumatoid arthritis and scleroderma) had extremely poor cosmetic results after breast radiation therapy (RT). The patient with rheumatoid arthritis received 5251 cGy at 210 cGy per day, followed by a 1600 cGy iridium-192 implant boost. Between 8 and 11 months post-RT she had severe breast fibrosis, retraction, and pain that required a mastectomy for relief. The patient with scleroderma received 5040 cGy at 180 cGy per day without a boost. Between 1 and 4 months post-RT the systemic symptoms of scleroderma progressed and the breast became hard and retracted. Both rheumatoid arthritis and scleroderma are chronic systemic diseases characterized by severe inflammation and an autoimmune component. The presence of scleroderma at or before treatment should be considered a contraindication to breast RT, whereas the presence of active rheumatoid arthritis should be considered a relative contraindication. An autoimmune mechanism will be presented to explain both the fibrosis and the systemic progression of collagen vascular disease that was observed.

Ultrasonic decalcification of the aortic annulus during aortic valve replacement

Aortic valve replacement for calcifica aortic stenosis requires meticulous debridement of the aortic annulus to effect optimal valve seating. Since 1987, we have used ultrasonic energy to debride the aortic annulus during aortic valve replacement in 56 patients. In our experience, ultrasonic debridement of the annulus is superior to traditional methods of debridement, affords improved seating of the valve, and may allow placement of a larger valve. Our follow-up ranges from 2 to 32 months (mean follow-up, 13 +/- 9 months) with 0% incidence of paravalvular leak or valve failure. We advocate the use of ultrasonic debridement as an adjunctive tool in aortic valve replacement.

A possible role for vitamins C and E in cataract prevention

Biochemical evidence suggests that oxidative stress caused by accumulation of free radicals is involved in the pathogenesis of senile cataracts. If so, appropriate amounts of the antioxidant vitamins C and E might be expected to prevent or retard the process. Such activity has been observed in several in vitro and in vivo studies of experimentally-induced cataracts. A recent epidemiologic study found that cataract patients tended to have lower serum levels of vitamins C, E, or carotenoids than did control subjects. The present investigation, which compared the self-reported consumption of supplementary vitamins by 175 cataract patients with that of 175 individually matched, cataract-free subjects, revealed that the latter group used significantly more supplementary vitamins C and E (P = 0.01 and 0.004, respectively). Because the results suggested a reduction in the risk of cataracts of at least 50%, a randomized, controlled trial of vitamin supplementation in cataract prevention may be warranted.