P1591Cardiovascular toxicity of ibrutinib: a pharmacovigilance study

Importance

Ibrutinib, a first in class Bruton tyrosine kinase inhibitor, has revolutionized treatment for several B-cell malignancies. However, early data suggested that ibrutinib was associated with supra-ventricular arrhythmias (SVA) and bleeding. Other types of cardiovascular adverse drug reactions (CV-ADR) induced by ibrutinib have been sporadically reported.

Objective

To determine the full spectrum of CV-ADR associated with ibrutinib and provide data concerning their clinical characteristics.

Design

An observational, retrospective, pharmacovigilance study

Setting

VigiBase, the World Health Organization's pharmacovigilance database.

Main outcomes and measures

A disproportionality analysis using reporting odds-ratios (ROR) and information component (IC). IC compares observed and expected values to find associations between drugs and ADR using disproportionate Bayesian reporting; IC025 (lower end of the IC 95% credibility interval) >0 is considered statistically significant.

Exposures

Exposure to ibrutinib versus entire database.

Results

Ibrutinib was associated with higher reporting of supraventricular arrhythmias (SVA; ROR: 23.1 [21.6–24.7]; IC025:3.97), central nervous system (CNS) hemorrhagic events (ROR: 3.7 [3.4–4.1]; IC025:1.63), heart failure (HF; ROR: 3.5 [3.1–3.8]; IC025:1.46), ventricular arrhythmias (VA; ROR: 4.7 [3.7–5.9]; IC025:0.96), conduction disorders (CD; ROR: 3.5 [2.7–4.6]; IC025:0.76), CNS ischemic events (ROR: 2.2 [2.0–2.5]; IC025:0.73) and hypertension (ROR: 1.7 [1.5–1.9]; IC025:0.4). CV-ADR occurred early after ibrutinib administration, as soon as after the first dose, with a shorter median time to onset of 27.5 days (IQR: 1–138.5 days) for CD (p<0.01, Kruskal-Wallis), as compared to CNS ischemic events (51 days; IQR: 17.5–160 days, p: 0.05 vs. CD), CNS hemorrhagic events (53.5 days; IQR: 20.3–183.3 days, p: 0.03 vs. CD), HF (54 days; IQR: 20–142.8 days, p: 0.05 vs. CD), VA (70 days; IQR: 28.5–152.5 days, p: 0.03 vs. CD), SVA (74 days; (IQR: 29.5–196.5 days, p: 0.0004 vs. CD) and hypertension (164 days; IQR: 20–274 days, p: 0.04 vs. CD). CV-ADR were associated with fatalities, with rates ranging from ∼10% (SVA and VA) to ∼20% (CNS events, HF and CD). More deaths occurred when SVA cases were associated with CNS hemorrhagic and/or ischemic events compared to their absence (15/52, 28.8% vs. 88/907, 9.7%, p<0.0001, respectively).

Conclusions

Severe and occasionally fatal cardiac events related to cardiac SVA, VA, CD, HF, hypertension, CNS hemorrhagic and ischemic events occur in patients exposed to ibrutinib. These events should be considered in patient care and in clinical trial designs.

Nocturnal Enuresis in India: Are We Diagnosing and Managing Correctly?

Nocturnal enuresis is a common problem affecting school-aged children worldwide. Although it has significant impact on child's psychology, it is always under-recognized in India and considered as a condition which will outgrow with advancing age. Nocturnal enuresis classified as primary or secondary and monosymptomatic or nonmonosymptomatic. Factors that cause enuresis include genetic factors, bladder dysfunction, psychological factors, and inappropriate antidiuretic hormone secretion, leading to nocturnal polyuria. Diagnosis consists of detailed medical history, clinical examination, frequency-volume charts, and appropriate investigations. The frequency-volume chart or voiding diary helps in establishing diagnosis and tailoring therapy. The first step in treating nocturnal enuresis is to counsel the parents and the affected child about the condition and reassure them that it can be cured. One of the effective strategies to manage enuresis is alarm therapy, but currently, it is not easily available in India. Desmopressin has been used in the treatment of nocturnal enuresis for close to 50 years. It provides an effective and safe option for the management of nocturnal enuresis. This review covers the diagnosis and management of nocturnal enuresis and introduces the concept of “bedwetting clinics” in India, which should help clinicians in the thorough investigation of bedwetting cases.

Maintenance therapy following induction chemoimmunotherapy in patients with diffuse large B-cell lymphoma: current perspective

BACKGROUND

Maintenance therapy has proven efficacy in indolent non-Hodgkin lymphoma (NHL), yet its role in diffuse large B-cell lymphoma (DLBCL) is an area of ongoing investigation. While DLBCL is potentially curable, >30% of patients relapse following front-line therapy and have a poor prognosis, especially those with refractory disease. Maintenance therapy holds promise to maintain response post-induction.

PATIENTS AND METHODS

Keyword searches were carried out in PubMed and congress abstracts of 'diffuse large B-cell lymphoma' and 'maintenance' and focused on phase II/III studies of maintenance following front-line induction.

RESULTS

Although used in indolent forms of NHL, studies of maintenance therapy with rituximab in patients with DLBCL responding to front-line R-CHOP (rituximab/cyclophosphamide/doxorubicin/vincristine/prednisone) have not improved efficacy and are not recommended. Targeted agents enzastaurin and everolimus reported results from the phase III studies PRELUDE and PILLAR-2, respectively, both of which showed no proven maintenance benefit following front-line chemoimmunotherapy induction. Overall, the reported efficacy results with these agents in the maintenance setting do not outweigh the risks. Lenalidomide for maintenance has been reported in three studies. Results from two phase II trials on lenalidomide maintenance revealed positive outcomes in higher-risk patients following induction, resulting in improved progression-free survival in relapsed DLBCL patients who were ineligible for transplantation. First analysis from the phase III REMARC trial showed a significant improvement in progression-free survival for lenalidomide versus placebo, with no difference in overall survival, following front-line R-CHOP induction in elderly patients.

CONCLUSIONS

Based on currently available studies of DLBCL maintenance therapies, initial results in front-line, as well as the relapsed setting, with immunomodulators such as lenalidomide show promise for further research to identify appropriate patients who would most benefit. Overall, this review of maintenance studies underscores the need for additional analyses of patient subtypes, clinical risk status, and molecular profiles, with careful consideration of study end points.

Family-led rehabilitation after stroke in India (ATTEND): a randomised controlled trial

BACKGROUND

Most people with stroke in India have no access to organised rehabilitation services. The effectiveness of training family members to provide stroke rehabilitation is uncertain. Our primary objective was to determine whether family-led stroke rehabilitation, initiated in hospital and continued at home, would be superior to usual care in a low-resource setting.

METHODS

The Family-led Rehabilitation after Stroke in India (ATTEND) trial was a prospectively randomised open trial with blinded endpoint done across 14 hospitals in India. Patients aged 18 years or older who had had a stroke within the past month, had residual disability and reasonable expectation of survival, and who had an informal family-nominated caregiver were randomly assigned to intervention or usual care by site coordinators using a secure web-based system with minimisation by site and stroke severity. The family members of participants in the intervention group received additional structured rehabilitation training-including information provision, joint goal setting, carer training, and task-specific training-that was started in hospital and continued at home for up to 2 months. The primary outcome was death or dependency at 6 months, defined by scores 3-6 on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]) as assessed by masked observers. Analyses were by intention to treat. This trial is registered with Clinical Trials Registry-India (CTRI/2013/04/003557), Australian New Zealand Clinical Trials Registry (ACTRN12613000078752), and Universal Trial Number (U1111-1138-6707).

FINDINGS

Between Jan 13, 2014, and Feb 12, 2016, 1250 patients were randomly assigned to intervention (n=623) or control (n=627) groups. 33 patients were lost to follow-up (14 intervention, 19 control) and five patients withdrew (two intervention, three control). At 6 months, 285 (47%) of 607 patients in the intervention group and 287 (47%) of 605 controls were dead or dependent (odds ratio 0·98, 95% CI 0·78-1·23, p=0·87). 72 (12%) patients in the intervention group and 86 (14%) in the control group died (p=0·27), and we observed no difference in rehospitalisation (89 [14%]patients in the intervention group vs 82 [13%] in the control group; p=0·56). We also found no difference in total non-fatal events (112 events in 82 [13%] intervention patients vs 110 events in 79 [13%] control patients; p=0·80).

INTERPRETATION

Although task shifting is an attractive solution for health-care sustainability, our results do not support investment in new stroke rehabilitation services that shift tasks to family caregivers, unless new evidence emerges. A future avenue of research should be to investigate the effects of task shifting to health-care assistants or team-based community care.

FUNDING

The National Health and Medical Research Council of Australia.

Antitumor effects of lenalidomide in combination with IDEC114 (anti CD80) in lymphoma bearing severe combined immunodeficiency (SCID) mouse model

3037

Background: Lenalidomide is a thalidomide analogue with immunomodulatory effects. We previously demonstrated that lenalidomide enhances the biological activity of rituximab. In our current work we further studied the effects of combining lenalidomide with IDEC114, a primatized anti-CD80 monoclonal antibody, which is undergoing clinical testing in B-cell lymphoma. Methods: Raji cells were exposed in vitro to lenalidomide (10μg/ml) or DMSO over five days. Changes in DNA synthesis were determined by [3H]-thymidine uptake. For ADCC and CMC assays, lenalidomide or control exposed Raji cells were labeled to 51Cr and then exposed to IDEC114 or isotype control and PBMC’s or human serum. For in vivo studies, 6–8 week old SCID mice were inoculated with 1×106 Raji cells via tail vein injection and after a period of 72 hours animals were divided into four cohorts. Lenalidomide was administered intraperitoneally (i.p) at 0.5mg/kg/dose on days +3, +4, +8, +9, +13, +14, +18 and +19. IDEC114 was administered via tail vein injection at 10mg/kg/dose on days +5, +10, +15 and +20. Difference in survival between treatment groups was performed by Kaplan-Meier analysis. Results: In vitro exposure of Raji to lenalidomide for five consecutive days enhanced the anti-proliferative effects of IDEC114 when compared to control. In addition, an improvement in IDEC114-associated ADCC was observed in lenalidomide-exposed Raji cells. In vivo treatment of SCID mice with lenalidomide in combination with IDEC114 led to prolongation of survival (44 days) compared to either biological agent alone (p<0.01). Conclusions: Our current research demonstrates that Lenalidomide when added to IDEC114 has augmented in vitro antitumor activity (i.e, antiproliferation and ADCC) and synergistic effects in vivo (i.e., prolongation of survival). We hypothesize and currently are evaluating whether the improvement in in vivo antitumor activity of IDEC114, when combined with Lenalidomide, is secondary to potential changes in the tumor microenvironment and/or IMiD-primed upregulation of NK cells and ADCC. This promising unique combination of biologics warrants evaluation as a clinical trial. (Supported by USPHS grant PO1-CA103985 from the National Cancer Institute.)

No significant financial relationships to disclose.

Outcomes and toxicities among octogenarians and nonagenarians with colorectal cancer (crc) treated with chemotherapy or concurrent chemoradiation - a single institution study

13514

Background: Chemotherapy is associated with an improved overall survival with acceptable toxicities in patients ≥ 70 years. However, little to no data exists regarding feasibility and tolerability of chemotherapy and/or radiation in CRC patients ≥ 80 years. The purpose of this study was to identify the trends of increased toxicity in this subgroup of patients. Methods: A retrospective study on patients ≥ 80 yrs treated for CRC with either chemotherapy alone or chemoradiation during the period of 1996- 2005 at Roswell Park Cancer Institute was conducted. Survival analysis was performed using the Kaplan-Meier method. Results: 29 patients were identified. 8 patients were diagnosed as having rectal cancer and received combined chemoradiation. 21 patients had colon cancer and received chemotherapy alone either in the adjuvant or metastatic setting. The median age was 82 years (range: 80–93). The median survival for all stages receiving chemo and/or radiation therapy was 37 months (95% CI: 27–53). The median survival for patients with stage IV disease was 6 months (95% CI: 5–33). Grade III/IV GI toxicities were seen in 59% (95% CI: 37–72%) of patients. Grade III/IV hematologic toxicities were seen in 17% (95% CI: 8–37%) of patients. Empiric chemotherapy dose reductions were implemented, starting the first cycle, in 90% (95% CI: 72–96%)of patients. Therapy had to be withheld in 34% (95% CI: 19–52%) of patients by more than 1 week due to toxicities in the first 2 months of treatment. Conclusions: Our study, demonstrates a higher rate of toxicities than previously reported for patients ≥ 70 years. This has occurred despite an initial dose-reduction in the majority of the treated population (90%). Octogenarian and nonagenarian CRC patients experienced a higher rate of GI toxicities during treatment, some of which were life threatening. This data supports the urgent need to conduct prospective studies to identify treatment recommendations for patients ≥ 80. Data from larger elderly phase II studies with median ages < 80 should not be extrapolated to octogenarians and nonagenarians.

No significant financial relationships to disclose.

Rituximab resistance and its association with changes in the internal domain of CD20 antigen and down-regulation of pro-apoptotic protein Bax and Bak in both rituximab-resistant cell lines (RRCL) and diffuse large B-cell lymphoma (DLBCL) patient (pt) samples

17509

Background: Resistance to rituximab (R) has been observed in lymphoma pts. To define the molecular basis for rituximab resistance we developed various RRCL and previously demonstrated changes in CD20 structure, membrane reorganization following rituximab exposure and deregulation of pro-apoptotic proteins Bax/Bak leading to rituximab/chemotherapy resistance. In our current work we evaluated changes in the structure/expression of CD20 and/or pro-apoptotic proteins in primary tumor specimens from DLBCL pts treated with rituximab in combination with CHOP (R-CHOP). Methods: We obtained frozen lymphoid material from patients with DLBCL who achieved a remission (sensitive lymphoma) or failed (resistant lymphoma) R-CHOP therapy. Protein lysates were obtained from each sample. Structural changes in CD20 were determined by Western blotting using various antibodies recognizing epitopes located in the internal (GST77 and 1439) and external domain (rituximab) of CD20. In addition, we studied the expression of Bax and Bak. Results: Variability in the expression and structure of CD20 was found in the pt samples. Rituximab binding to its surface CD20 antigen was preserved in all patients. However, differences in C- and N-terminal expression were found across DLBCL specimens. In addition, down-regulation of Bax/Bak was observed in some pts with resistant lymphomas. Patients who responded to R-CHOP were noted to either have an intact CD20 and/or express Bax/Bak. On the other hand, resistant lymphomas had altered CD20 isoforms and a downregulation of Bax/Bak. Conclusions: Our current preliminary data suggests a positive correlation to our pre-clinical data generated from B-cell NHL cell-lines and will be evaluated in a larger number of primary NHL tumor specimens.

No significant financial relationships to disclose.

Partial thromboplastin time: prediction of adverse events and poor prognosis by low abnormal values

BACKGROUND

Clinical observations suggest an increased incidence of bleeding and thrombosis in association with a shortened partial thromboplastin time (PTT).

OBJECTIVE

To determine whether abnormally fast PTTs are associated with an increased risk of death, thromboses, bleeding, and the overall occurrence of morbid events.

METHODS

The medical records of 199 patients admitted in a 1-year period to a Veterans Affairs medical center were reviewed for PTTs and the events of death, thromboses, and severe bleeding. Group 0 (n = 49) consisted of patients with abnormally fast PTTs (<23 seconds). Group 1 (n = 50) consisted of patients with fast normal PTTs (23-25 seconds), and the control group, group 2 (n = 100), contained patients with PTTs from 28 to 31 seconds. The Cox proportional hazards regression was used to analyze the time-independent covariates of PTT groups, surgery, cancer, and other clinical variables as predictors of 3 outcome variables: bleeding, thrombosis, and death.

RESULTS

Of the covariates examined, the PTT was found to be the most significant predictor of poor outcome. A statistically significant association was found between the PTT and time to death (P<.001), thrombotic events (P<.001), and bleeding (P<.006), and between the PTT and overall occurrence of morbid events (P<.001). Furthermore, survival curves showed that the greatest hazards of death, thrombosis, bleeding, and overall morbidity consistently occurred in group 0 compared with groups 1 and 2.

CONCLUSIONS

Abnormally fast PTTs, particularly if confirmed on repeated testing, indicate a significant risk of subsequent death, thrombosis, bleeding, and overall morbidity. Careful examination of patients with low PTTs may reduce such associated morbidity and mortality.

Growing skull fractures: a clinical study of 41 patients

Growing skull fractures are rare complications of head injury, occurring almost exclusively in infants and children under the age of three. A retrospective review at our Institute yielded 41 patients with this entity over a period of 20 years (1975-1995). The age at presentation ranged from less than 1 year to 62 years, with 33 (80.5%) patients being less than 5 years of age. The cause of injury was either a fall from a height (93%) or a road traffic accident. The most common location of a growing skull fracture was either parietal or frontoparietal (56%). One patient had a posterior fossa growing skull fracture. CT scan was performed in 19 patients which demonstrated an underlying porencephalic cyst, hydrocephalus or a cyst communicating with the ventricle. In 5 children, a ventriculo-peritoneal shunt alone was performed. Twenty four patients underwent a duro- and cranioplasty while a duroplasty alone was performed in 8 patients. The material used for cranioplasty included acrylic, wire mesh, steel plates or autologous bone. Three patients died, one due to an anaesthetic complication and two as a result of postoperative meningitis. Post-operative CSF leaks occurred in 3 patients, which were managed by a lumbar drain. Six patients had local wound infection.

Tests of the double-strand break, lethal-potentially lethal and repair-misrepair models for mammalian cell survival using data for survival as a function of delayed-plating interval for log-phase Chinese hamster V79 cells

Our data (Reddy et al., Radiat. Res. 141, 252-258, 1995) on the kinetics of the repair of potentially lethal damage in log-phase Chinese hamster V79 cells are used to test some predictions which arise from the different assumptions of the repair-misrepair (RMR) (C. A. Tobias, Radiat. Res. 104, S77-S95, 1985), lethal-potentially lethal (LPL) (S. B. Curtis, Radiat. Res. 106, 252-270, 1986) and double-strand break (DSB) (J. Y. Ostashevsky, Radiat. Res. 118, 437-466, 1989) models. The LPL model defines the time available for repair of PLD (t(rep)) as the time taken to reach maximal survival in a delayed-plating recovery experiment. Those data show that after this time has elapsed, contrary to the expectation of the LPL model, survival can be increased by changing the medium used for delayed plating from fresh growth medium to conditioned medium. According to the RMR model, all potentially lethal lesions should also be committed by that time and be unavailable for repair in the new medium. Only the DSB model correctly predicted that PLD (= DSBs) would still be available for repair after that time. Second, data for split-dose recovery are used to predict the first-order kinetics time constant for DSB repair (tau(DSBR)) using the DSB model (24 +/- 1.5 min). This value is nearly identical to the value of 27 +/- 1 min determined from the data obtained by Cheong et al. using pulsed-field gel electrophoresis (PFGE) (Mutat. Res. 274, 111-122, 1992). The value based on PFGE is used to calculate the value of t(rep) predicted by the DSB model (2.6 +/- 0.1 h), which agrees with the value determined experimentally as the time when changing the delayed-plating medium from growth medium to conditioned medium no longer gives the full recovery seen with delayed plating in conditioned medium (2.5 h). However, some recovery was seen for a change in the medium (growth medium to conditioned medium) up to 5-6 h postirradiation. Reanalysis of the original data on DSB repair shows that they are consistent with two first-order repair rates (18 +/- 7 min and about 52 min). These results are consistent with two pools of DSBs (or cells), each with their own t(rep). The early t(rep), associated with tau(fast), is predicted to be 1.7 +/- 0.7 h, and the late t(rep), associated with tau(slow), is predicted to be about 5 h. Both values are in excellent agreement with the times at which changing from growth medium to conditioned medium no longer gives the full recovery seen in conditioned medium only (the early t(rep)), and the time when changing from growth medium to conditioned medium produces no further increase in survival (the late t(rep)), respectively. It is noted that attempts to correlate radiosensitivity with the rates of DSB repair, rather than using an explicit model such as the DSB model, are unlikely to be productive since survival depends on both tau(DSBR) and t(rep) (as defined in the DSB model) and the latter may be the more important determinant of radiosensitivity (as it appears to be for ataxia telangiectasia cells compared to normal fibroblasts and for irs compared to V79 cells).

Nutrient dilution before and after X irradiation increases the radioresistance of log- and plateau-phase Chinese hamster V79 cells

Previous observations have shown that cells cultured in standard growth medium (100%) demonstrated similarly enhanced survival when incubated postirradiation either in non-growth-promoting conditioned medium or in growth-promoting 40% growth medium (Reddy and Lange, Radiat, Res. 119, 338-347, 1989). From these results, it was suggested that nutrient dilution altered radiosensitivity by a mechanism independent of progression of cells through the cell cycle. In this study, we have examined the effects on radiosensitivity of incubation in 40% growth medium prior to irradiation on both log- and plateau-phase Chinese hamster V79 cells and the effects on the distribution of cells in the cell cycle of incubation in 40% or 100% growth medium before and after irradiation. Radioresistance increased by a factor of 1.5-1.6 compared to 100% growth medium for both log-phase and plateau-phase cells cultured in 40% growth medium prior to X irradiation and incubated in either 40% growth medium or conditioned medium after X irradiation. The cell cycle distributions of log-phase cells in 100% and 40% growth medium before irradiation were identical. The change in cell cycle distribution induced by 10 Gy did not differ among log-phase cells incubated for 3 h postirradiation in 100% growth medium, 40% growth medium or conditioned medium. These results, in addition to supporting our previous conclusions, demonstrate that culturing prior to irradiation in 40% growth medium alone increases cell survival and that incubation in 40% growth medium before and after irradiation maximizes the survival of V79 cells.

Importance of anatomical subsite in correlating risk factors in cancer of the oesophagus--report of a case--control study

In Bangalore, cancer of the oesophagus is the third most common cancer in males and fourth most common in females with average annual age-adjusted incidence rates of 8.2 and 8.9 per 100,000 respectively. A case-control investigation of cancer of the oesophagus was conducted based on the Population-based cancer registry, Bangalore, India. Three hundred and forty-three cases of cancer of the oesophagus were age and sex matched with twice the number of controls from the same area, but with no evidence of cancer. Chewing with or without tobacco was a significant risk factor. In both sexes chewing was not a risk factor for cancer of the upper third of the oesophagus. Among males, non-tobacco chewing was a significant risk factor for the middle third but not for the other two segments and tobacco chewing was a significant risk factor for the lower third of the oesophagus, but not for the other two segments. Bidi smoking in males was a significant risk factor for all three segments being highest for the upper third, less for the middle third and still less for the lower third. The risk of oesophageal cancer associated with alcohol drinking was significant only for the middle third.

Chinese hamster V79 cells harbor potentially lethal damage which is neither fixed nor repaired for long times after attaining maximal survival under growth conditions

The kinetics of the repair and fixation of potentially lethal damage (PLD) was studied in log-phase Chinese hamster V79 cells. The postirradiation (10 Gy) survival of cells treated with hypertonic saline increased when these cells were incubated further in conditioned medium but not in growth medium, indicating that damage which is neither fixed by hypertonic saline nor amenable to repair in growth medium is nonetheless repaired in conditioned medium. Recovery of X-irradiated cells incubated in growth medium or in conditioned medium was maximal by about 70 min and was two times higher in conditioned medium than in growth medium. Cells incubated in growth medium for 70-120 min postirradiation continued to repair damage when subsequently shifted to conditioned medium and attained the same survival as that of cells in conditioned medium only. Thus PLD is not fixed by the time the recovery plateau has been attained in growth medium, and this unfixed PLD can still be repaired when cells are shifted to conditioned medium. To study the kinetics of fixation of PLD (without hypertonic saline), the survival of cells incubated in growth medium for up to 9 h postirradiation was compared with that for cells incubated in growth medium for different times followed by incubation in conditioned medium. These results show that the damage was neither fixed nor misrepaired in growth medium but rather remained unrepaired for up to 2 h, and that damage fixation in growth medium does not begin until after 2 h and is completed by 6 h postirradiation.

Is there a cell-to-cell contact effect on the X-ray dose-survival response of mammalian cells?

While a cell-to-cell contact effect has been reported for a Chinese hamster subline V79-171B, this was not observed for another subline V79 171-S. Therefore, we tested whether the cell-to-cell contact effect on cell survival depended on the cell line or the experimental conditions used. We have cultured and compared both sublines under identical conditions. Both sublines, cultured in Eagle's minimal essential medium (MEM) with 15% serum, had nearly identical cell doubling times and radiosensitivities. For both sublines, the survival of spheroid and monolayer cells subcultured immediately after irradiation were nearly the same, i.e., a radio-protective contact effect for spheroid cells was absent. Under conditions favorable for the repair of radiation induced damage, cell survival was higher for cells in monolayers than for cells in spheroids. Potentially lethal damage (PLD) repair and sublethal damage (SLD) repair were present in both sublines. However, the magnitude of expression of PLD by hypertonic saline was higher for monolayer than for spheroid cells. We conclude that: 1) the reported differences between V79 sublines (contact effect on survival) appear to be dependent on differences between experimental conditions rather than on cell type; 2) delayed plating technique does not detect PLD repair in round spheroid cells; and 3) detection of repair by split dose is independent of cell shape and/or two- or three-dimensional culture conditions.

Detection of X-ray damage repair by the immediate versus delayed plating technique is dependent on cell shape and cell concentration

A method commonly used to measure the ability of cells to repair potentially lethal damage (PLD) is to compare immediate plating (IP) and delayed plating (DP) survival. Lower cell survival under IP conditions relative to that after DP conditions has been interpreted to indicate a higher ability of cells to repair potentially lethal damage (PLD) under DP conditions. However, this IP radiosensitization has not been observed in several cell lines and tumor models. IP conditions involve treatment of cells with trypsin and plating them into fresh growth medium. We have investigated the possibility that radiosensitization under IP conditions may be related to both the cell-shape and the nutrient concentration in growth medium (GM, MEM + 15% serum). This idea predicts that the IP and DP survival of spheroids will show a response similar to the IP survival of cells in monolayers and that the IP and DP survival of crowded monolayer cells in high densities will be the same. Chinese hamster V79 cells grown in monolayers (spread cells) and spheroids (clumps of round cells) were used. The IP survival was lower than the DP survival for spread log phase monolayer cells but not for round log phase cells in spheroids. Radiosensitization of cells by fresh (as opposed to spent) growth medium was absent for high density plateau phase cells in monolayers at or above 2 x 10(6) cells/ml. However, PLD repair could be demonstrated in spheroid cells and in high density plateau phase cultures by exposing cells to hyperthermia or hypertonic saline. Comparison of immediate plating versus delayed plating survival detects PLD repair only in well spread low density monolayer cells, but not in round spheroid cells nor in dense monolayer cells at > 10(7) cells/25 cm2 flask/5 ml medium. The absence of a difference between IP and DP cell survival does not mean that PLD repair is absent. Incorrect prediction of tumor response to radiotherapy can occur when PLD repair capacity is assayed as a ratio of DP/IP survival. More than one method must be used to measure the capacity of cells to repair their PLD.

Trypsin-induced changes in cell shape and chromatin structure result in radiosensitization of monolayer Chinese hamster V79 cells

Trypsin is the enzyme commonly used to prepare single cell suspensions from monolayer and spheroid cultures, both to determine survival and to assay DNA damage. Trypsin induces rounding, dissociation and radiosensitization of anchorage-dependent cells. Radiosensitivity and chromatin structure were compared between trypsin-treated (0.05%) round V79 cells from monolayers and spheroids vs. untreated spread monolayer cells in situ. The fluorescent halo technique was used to measure the changes in DNA supercoiling in nucleoids isolated from control and irradiated round and spread cells. Maximal halo diameters, the amount of initial and residual radiation-induced DNA damage (estimated from nucleoid halo diameter changes), and the radiosensitivity were higher in round cells than in spread monolayer V79 cells. The effects on cellular radiosensitivity and maximal halo diameter of other agents which also round and dissociate cells, e.g. 0.25% trypsin, pronase E and a non-enzymatic cell-dissociation solution, were similar to those of 0.05% trypsin. In LY-S cells, which are anchorage-independent, DNA loop size, the initial amount of DNA damage and radiosensitivity were not affected by trypsin. We suggest that the higher radiosensitivity of anchorage-dependent cells under immediate trypsinization and plating conditions, compared to cells with postirradiation in situ repair incubation, is due to correlated changes in cell shape and chromatin structure.

Serum, trypsin, and cell shape but not cell-to-cell contact influence the X-ray sensitivity of Chinese hamster V79 cells in monolayers and in spheroids

Nutrient concentration in the growth medium and trypsin affect cellular radiosensitivity in a manner that is related to cell shape (Reddy, Stevenson, and Lange, Int. J. Radiat. Biol. 55, 105-117 (1989); Reddy and Lange, Radiat. Res. 119, 338-347 (1989]. Hence we hypothesized that the concentration of serum in the medium could influence the X-ray sensitivity of cells and that the spread cells in monolayers and round cells in spheroids may differ in their response to the radiosensitizing effect of trypsin. We compared the X-ray sensitivity of monolayer and spheroid cells grown for 19 +/- 1 h in MEM supplemented with 5 or 15% serum. Cells were trypsinized and plated either immediately before, or 2.5 +/- 0.5 h after, irradiation and incubation for repair in situ. Survival of cells in monolayers and in spheroids was higher in MEM with 5% serum than with 15% serum. Trypsin treatment affected the shape and radiosensitivity of cells in monolayers but not in spheroids. When all cells were grown in the same serum concentration and a 2.5-h postirradiation incubation was allowed prior to trypsinization, the X-ray sensitivity of cells in spheroids was greater than that of cells in monolayers. The survival of cells in spheroids became equal to that of monolayer cells when cells in spheroids were converted to monolayers by placing them in 25-cm2 flasks and allowing them 3 h to attach and spread. Cell cycle distributions were nearly the same in monolayers and spheroids cultured in MEM with 5 or 15% serum. We conclude that: (1) serum concentration in the growth medium and trypsin do appear to contribute to the differences in the radiosensitivity of spheroids and monolayer V79 cells; (2) these differences are associated with changes in cell morphology.

The saturated repair kinetics of Chinese hamster V79 cells suggests a damage accumulation--interaction model of cell killing

The aim of this study is to determine whether the repair process in log-phase Chinese hamster V79 cells exposed to X rays is unsaturated, saturable, or saturated. The kinetics of recovery from damage induced by 2 to 14 Gy of 250 kVp X rays was studied by treating cells with 0.5 M hypertonic saline for 20 min at different postirradiation repair intervals. From the kinetic data, the repair half-time (t1/2), the repair time (time needed to attain maximal survival), and the recovery ratio were calculated. The results show that the t1/2 (1.42 min/Gy) and the repair time (6.04 min/Gy) increase linearly with dose, the logarithm of the recovery ratio increases linear-quadratically with dose, and the D0 increases linearly with repair interval at a rate of 2.4 cGy/min. From these results we suggest a model: the repair of damage (undefined lesions) necessary for cell survival is effected by a repair process (t 1/2 of 1.42 min/Gy) which is saturated at doses as low as 2.4 cGy; repair saturation leads to a dose-dependent accumulation of repairable lesions; and interaction among accumulated repairable lesions results in the induction of irreparable (lethal) lesions. We call this the accumulation-interaction model of cell killing by low-LET radiation.

Similarities in the repair kinetics of sublethal and potentially lethal X-ray damage in log phase Chinese hamster V79 cells

We have compared the repair kinetics of X-ray-induced sublethal damage (SLD) and potentially lethal damage (PLD) in V79 cells during postirradiation incubation in growth medium at 37 degrees C. Kinetics of SLD repair were studied by dose fractionation (D1 + D2 = 2 + 2, 4 + 2, 4 + 4, 10 + 4 and 10 + 7 Gy). Kinetics of PLD repair were studied by incubating cells with 0.5 M hypertonic saline (HS) for 20 min at various times after irradiation. The repair of SLD, after 2, 4 and 10 Gy, was complete in about 11, 23 and 62 min, respectively. This repair time was independent of the magnitude of dose D2 (test dose). The repair of PLD, after 2, 4 and 10 Gy, was also complete in about 9, 23 and 61 min, respectively. These data indicate that: (1) the kinetics of repair of SLD for a given dose are independent of the magnitude of the test dose D2; (2) the time taken to complete the repair (repair time) is dependent on dose D1, i.e. the larger the dose D1 the longer the repair time; (3) for a given dose, the repair times assayed either by dose fractionation or by HS treatment are similar; and (4) similarities in the repair times may imply that SLD and PLD are the same. The relationship between the repair kinetics and the shape of the shoulder on fractionated survival curves is discussed.

Cell cycle progression delay in conditioned medium does not play a role in the repair of X-ray damage in Chinese hamster V79 cells

We tested our hypothesis that the lower survival of X-irradiated cells in growth medium (GM) relative to that in conditioned medium (CM) is due to differences in nutrient concentration levels rather than to differential effects on cell progression and growth. Chinese hamster V79 cells in log and unfed plateau phase, grown in Eagle's minimal essential medium (MEM) with 15% serum (100% GM), were irradiated. Before plating, cells were incubated in situ in various concentrations of MEM with serum (GM, normal cell progression) or MEM without serum or in CM (no cell progression). Cell survival was the lowest in 100% MEM with or without serum and increased with the decrease in MEM and serum concentrations, reaching a plateau in 40% MEM or 40% growth medium (40% MEM with 6% serum), similar to that in conditioned medium. Growth kinetics was the same in 40 and 100% growth medium, but the D0 of cells in 40% growth medium was higher than that of cells in 100% GM. Similarly, the D0 of cells in 40% MEM was higher than that of cells in 100% MEM, although cell progression was absent in both media. The radiation sensitivity of cells was the same in 40% GM with progression and in 40% MEM and CM with no progression. Cells in low-nutrient media were flatter than those in 100% MEM or GM. There was a correlation between the nutrient concentration in the medium postirradiation and the D0. This correlation was independent of the presence or absence of serum and thus independent of cell cycle progression. The cell morphology which is dependent on the nutrient concentration appears to influence the ability of a fraction of cells to repair their radiation damage.

Trypsinization and the radiosensitivity of mitotic and log phase Chinese hamster V79 cells exposed to 250 kVp X-rays

We studied the influence of trypsin-induced morphological changes on the radiosensitivity of cells plated at either low (4-600/cm2) or high (2 x 10(4)/cm2) density and grown overnight before treatments. Trypsin treatment induced contraction and rounding of spread cells. The radiosensitivity of cells trypsinized and plated either: (1) immediately before [(a) D0 = 1.7 Gy for cells at low-, and (b) 1.5 Gy at high-density] or (2) immediately after (D0 = 1.6 Gy, high-density cells) irradiation was higher than that of (3) cells at high density, irradiated and delayed plated [cells remained spread until the completion of potentially lethal damage repair (PLDR) and trypsinization, D0 = 2.2 Gy], and (4) cells at low density which were neither delayed plated nor trypsinized (i.e. remained spread) after irradiation (Do = 2.4 Gy). These data show that PLDR is reduced in trypsin-treated cells of both high (compare 1b and 2 with 3) and low (compare 1a with 4) density cultures; the latter comparison provides a direct measure of the trypsin effect. Since the comparison between conditions 1 and 2 vs. 3 and 4 is of round vs. spread cells, PLDR appears to be influenced by the cell's morphological state. Kinetic studies showed that when cells were incubated in growth medium to recover from trypsin-induced effects before irradiation, the radiation sensitivity of spread cells (plated in situ), but not of those remaining rounded (in suspension until plating and irradiation), decreased and became equal to that of delayed plated high-density cells. Neither irradiated cells treated with hypertonic saline, nor mitotic cells, showed the trypsin effect. From these results we suggest that: (1) trypsin-induced cell contraction affects the ability of cells to repair radiation damage, (2) spread cells are better able to repair PLD than rounded cells, (3) immediate plating survival of cells in high-density cultures may not represent their intrinsic radiosensitivity and (4) cell-to-cell contact is not necessary for log phase cells to repair PLD.

Local RF capacitive hyperthermia: thermal profiles and tumour response

At the Cancer Institute we are using RF capacitive hyperthermia as an adjuvant to radiotherapy and/or chemotherapy in the local control of soft tissue sarcomas. We have studied the influence of bolus conductivity, electrode and phantom sizes on the rate of heating of agar phantoms. We have varied the bolus conductivity by varying the saline concentration in the bolus bags from zero to 2.0 per cent, during heating. We found that the rate of heating of phantoms increases and that of the bolus decreases with the increase in the saline concentration of bolus up to 1 per cent, irrespective of phantom and electrode sizes. However, for a given size of electrodes the rate of heating decreased with the increase in the phantom size. When the diameter and height of the phantom were equal to the diameters of electrodes the rate of heating of the phantom was nearly uniform. However, when the diameter of the phantom was larger than that of electrodes the rate of heating in the radial axis decreased with the increase in the radial distance. On the basis of this data we suggest the use of electrodes larger in size by 1.0-3.0 cm than the size of the tumour, where the size of the anatomical site to be heated is larger than the electrode size to be used. Phantom and clinical data have indicated that the presence of bone in the field of heating can lead to hot spots. Preliminary clinical results have shown that the response of sarcomas to thermo-chemo-radiotherapy was superior to that of either thermo-radiotherapy or radiotherapy alone.

Serratus anterior disruption: a complication of rheumatoid arthritis

Pathology influencing the serratus anterior muscle contributes to classical medial winging of the scapula. Serratus anterior weakness or injury interferes with regular shoulder movement as this muscle stabilizes the medial border of the scapula against the thorax and rotates the scapula upward and laterally with arm elevation. Traumatic injury to the serratus anterior muscle without electrodiagnostic evidence of neurogenic involvement has only been reported once previously. We report an unusual case of disruption of the serratus anterior as a complication of rheumatoid arthritis. Involvement of the long thoracic nerve was ruled out by electromyography and nerve conduction studies. The injury occurred during routine activities of daily living and was complicated by a recurring subscapular hematoma. Contributing factors of shoulder joint contractures and coagulation abnormalities were associated with the course and treatment of rheumatoid arthritis. Initial treatment was by joint immobilization and reversal of coagulation abnormalities. Later treatment was directed toward joint protection and gradually increasing range of motion exercises.

A possible mechanism of detoxification of copper, in the fresh water mollusc, Lymnaea luteola

The cidal effect of copper sulphate on pulmonate snail host Lymnaea luteola was studied in relation to lipid metabolism. Alterations in the levels of glycerol, phospholipids, glycerides, sterols, sterol esters and free fatty acids due to copper sulphate treatment are recorded in foot, mantle and digestive gland of this mollusc. These results have been interpreted as part of a mechanism of detoxification, prevalent in this fresh water mollusc.

Genetic control of budding-cell resistance in the diploid yeast Saccharomyces cerevisiae exposed to gamma-radiation

The gamma-radiation response of stationary and budding cells of wild-type diploid strains (RAD) and radiation-sensitive strains rad2, 6, 9, 18, 50-55, 57 and rec4 was studied. As compared with the wild-type strains, mutants generally showed enhanced sensitivity in both stages of the cell cycle. Budding-cell resistance was totally absent from rad50-55 strains. Mutants rad6, 9 and 18 showed some degree of budding-cell resistance. The response of rad2 and rec4 strains was identical with that of the corresponding wild-type strains. These results suggest that the pathway dependent upon the expression of RAD50-55 loci functions more efficiently in budding cells compared with the pathway dependent on RAD2 and RAD6, 9 and 18 loci. Recombination between sister chromatids appears to play an important role in budding-cell resistance, and this process is under the control of the RAD52 repair pathway. The relationship between the repair pathways associated with budding-cell resistance and post-irradiation cellular recovery (LHR) is discussed.

Somatosensory evoked potentials: their predictive value in right hemiplegia

The purpose of this study was to determine the correlation, if any, between the status of the somatosensory evoked potential (SEP) and functional change in the right upper extremity of patients with right hemiplegia following stroke. Sixty-eight such patients were admitted to a rehabilitation hospital for intensive treatment from 3 to 8 weeks after onset. All had SEP studies by stimulation of the median nerves of the upper extremities and had complete medical, neurologic and functional evaluations. Forty-two patients had an absent SEP; of these only one showed some functional gain in the right upper extremity (RUE) at discharge. Of 14 patients having diminished SEP, 5 (36%) had some functional gain in RUE at discharge. Of 8 having normal SEP, 3 (38%) showed some functional gain on discharge. None of these 64 patients had any function in RUE on admission. Four patients had a normal SEP and some function on admission, with an increase of function on discharge. Of right hemiplegic patients who showed absence of SEP and nonfunction of RUE on admission, 98% gained no functional return in RUE during hospitalization. These data suggest that SEP studies in stroke patients offer useful information for prognosis and rehabilitation programming.

Comparison of sensitivity of rad mutants of diploid yeast to heat and gamma radiation: cellular target for heat inactivation

Wild type and radiation-sensitive mutants rad 53, 54 and 55 of the diploid yeast Saccharomyces cerevisiae, in stationary and log phase were exposed to gamma radiation and hyperthermia (51 degrees C) in order to compare their sensitivity to these agents. The wild type diploid strain exposed to gamma rays showed a sigmoidal survival curve both in stationary and log phase cultures. Log phase cells were significantly more resistant than stationary phase cells. When compared to wild type, the gamma radiation response of the mutants indicated that the mutations in these RAD loci render the cells sensitive in stationary phase and very sensitive in log phase. The response of mutants to hyperthermia was similar to that of wild type cells in both the phases. The log phase cells of both wild type and mutants wee gamma radiation response of the mutants indicated that the mutations in these RAD loci render the cells sensitive in stationary phase and very sensitive in log phase. The response of mutants to hyperthermia was similar to that of wild type cells in both the phases. The log phase cells of both wild type and mutants wee gamma radiation response of the mutants indicated that the mutations in these RAD loci render the cells sensitive in stationary phase and very sensitive in log phase. The response of mutants to hyperthermia was similar to that of wild type cells in both the phases. The log phase cells of both wild type and mutants were more sensitive to heat than stationary phase cells. These results suggest that the RAD loci are not involved in the repair of hyperthermic damage. Since it is known that the products of the RAD genes are involved in the repair of DNA damage, the wild type response of these rad mutants to hyperthermia indicates that the DNA may not be the principal target for hyperthermic killing. Furthermore, the enhanced thermal sensitivity of log phase cells, containing higher amounts of active enzymes and sensitive membrane, strongly suggests that proteins and/or membranes could be the primary targets for thermal inactivation.

Modification of high LET radiation-induced damage and its repair in yeast by hypoxia

The lethal response of a diploid yeast strain BZ34 to densely ionizing radiations from the reaction 10B(n, alpha)7 Li was studied. The values for relative biological effectiveness (r.b.e.) and oxygen enhancement ratio (o.e.r.) for this radiation compare favourably with the data obtained with charged particles on the same strain of yeast. Recovery from potentially lethal damage was also studied by post-irradiation holding under non-nutrient conditions. In order to understand the role of oxygen in the recovery process, the investigation covered the following treatment regimens: (a) aerobic irradiation and aerobic holding (A-A), (b) aerobic irradiation and hypoxic holding (A-H), (c) hypoxic irradiation and hypoxic holding (H-H) and (d) hypoxic irradiation and aerobic holding (H-A). It has been found that the presence of oxygen is essential for recovery from the damage induced by both gamma rays and high linear energy transfer (LET) radiations. The extent of recovery was larger for gamma-induced damage than for damage induced by high LET radiation (alpha + 7Li) for the A-A condition. In the H-H condition, while only a slight recovery was seen for gamma-induced damage, it was totally absent for high LET damage. For the modality A-H, it was found that there is not recovery from the sparsely ionising gamma radiation-induced damage. The implications of these results for the treatment of malignant tumours by radiotherapy are briefly discussed.

Non-equivalence of YEPD and synthetic complete media in yeast reversion studies

In yeast reversion studies, assay of the total number of cells is made by plating irradiated cells on agar plates containing yeast extract, peptone and dextrose (YEPD) medium. The number of revertants are scored by plating cells on synthetic complete (SC) medium deficient in the particular nutrient for which the reversion is tested. In this procedure equivalence for cell survival between the YEPD and the SC media is always assumed. However it is shown in this paper that this assumption is valid only up to dose levels where cell killing is not significant. At high doses, survivals on the two media differ significantly from each other for both high and low LET radiations. This difference influences the slope of the reversion frequency curve at high doses. Since the reversion frequency is expressed with reference to the number of survivors after a given radiation dose, it is essential to see that the same chance of survival is offered to the reverted and unreverted cells. Even though reversion is reported to vary linearly with dose, it is found that this linearity is restricted only to dose levels where cell killing is not significant. At higher doses, the reversion frequency varies in a very complex manner with dose for both high and low LET radiations. The complexity depends further on the reference medium chosen.