OBJECTIVE: The apoptosis pathway is a vital mechanism in vivo that functions to eradicate genetically damaged cells prone to malignancy. The purpose of this study was to determine whether oral contraceptives, which confer significant protection against subsequent epithelial ovarian cancer, induce apoptosis in the ovarian epithelium. METHODS: Female cynomolgus macaques (N = 75) were randomized to receive a diet for 35 months containing either no hormones, the oral contraceptive Triphasil (Wyeth-Ayerst Laboratories, Philadelphia, PA), the estrogenic component of Triphasil (ethinyl estradiol) alone, or the progestin component of Triphasil (levonorgestrel) alone, each administered in a cyclic fashion. At study termination, the animals underwent ovariectomy and the ovarian epithelium was examined morphologically and immunohistochemically for apoptosis. The percentage of ovarian epithelial cells undergoing apoptosis was measured in each animal and compared between the treatment groups. RESULTS: The median percentage of ovarian epithelial cells undergoing apoptosis by treatment was control (3.8%), ethinyl estradiol (1.8%), Triphasil (14.5%), and levonorgestrel (24.9%). Compared with control and ethinyl estradiol-treated monkeys, a statistically significant increase in the proportion of apoptotic cells was noted in the ovarian epithelium of monkeys treated with the oral contraceptive Triphasil (P < or = .01) or levonorgestrel (P < .001), with a maximal effect (six-fold) seen in the group treated with levonorgestrel alone. CONCLUSION: Oral contraceptive progestin induces apoptosis in the ovarian epithelium. Given the importance of the apoptosis pathway for cancer prevention, an effective chemopreventive strategy may be possible using progestins or other agents that selectively induce apoptosis in the ovarian epithelium to prevent the development of ovarian cancer.

Animals↗

PubMedDate not supplied

The effects of indoor pollution on Arizona children.

The respiratory health of a large group of Arizona school children who have been exposed to indoor pollutants--tobacco smoke and home cooking fumes--is reported. A significant relationship was found between parental smoking and symptoms of cough, wheeze, and sputum production. Also, children in homes where gas cooking fuel was used had higher rates of cough than children in homes where electricity was used. No differences in pulmonary function or yearly lung growth rates occurred among subjects grouped by exposure to tobacco smoke or cooking fuel. Thus, parental smoking and home cooking fuel affected cross-sectional respiratory symptom rates in a large group of Arizona school children. Study of pulmonary function, however, revealed no lung function or lung growth effects during 4 yr of study.

Air Pollutants↗

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Radiation therapy and surgery for fibrosarcoma in 33 cats.

Thirty-three cats with histologically confirmed fibrosarcomas were treated with radiation therapy followed by surgery. The median (95% confidence interval) disease free interval and overall survival were 398 (261,924) and 600 (lower limit 515) days, respectively. There were 19 treatment failures; 11 cats had only local recurrence, 4 cats developed metastatic disease, 3 cats had local recurrence followed by metastasis, and 1 cat developed simultaneous local and distant disease. Twelve cats are alive and disease free. Two cats died without evidence of treatment failure. The presence of tumor cells at the margin of resected tissue after radiation was the only variable which influenced treatment success. The median (95% confidence interval) disease free interval in 5 cats with tumor cells at the margin of the resected specimen was 112 (94,150) days versus 700 (lower limit 328) days for 26 cats with negative tumor margins, p < 0.0001. We did not identify a relationship between tumor volume, number of prior tumor excisions, concomitant use of chemotherapy or various descriptors of the radiation therapy technique and disease free interval.

Animals↗

PubMedDate not supplied

Radiation therapy for incompletely resected canine mast cell tumors.

The records of 56 dogs treated with megavoltage radiation for mast cell neoplasia were reviewed to determine the efficacy of this treatment modality. Total radiation dose ranged from 45 to 57 Gray (Gy), dose per fraction ranged from 3.0 to 4.0 Gy, and radiation treatment time ranged from 14-28 days. Median disease free interval (95% CI) was 32.7 (19-70) months. Median disease free interval for dogs older than 7.5 years was 15 (lower limit 7) months as compared to 62 (lower limit 20) for dogs younger than 7.5 years of age (p = 0.006). Median disease free interval for dogs with measurable disease was 12 (lower limit 5) months as compared to 54 (32-70) months for dogs with microscopic disease (p = 0.006). Radiation treatment time was also significantly related to disease free interval. Median disease free interval for dogs treated longer than 22 days was 12 (7-19) months as compared to greater than 50 (lower limit 20) months for dogs treated in 22 or fewer days (p < 0.001). This appeared to be due to more recurrences in dogs treated with 3-per-week fractionation and suggests that tumor proliferation in the interfraction interval may be important. Sex, tumor location, histologic grade, WHO clinical stage, number of radiation fractions, total radiation dose, and dose-per-fraction, as well as the following "yes/no" variables: steroids given, surgery prior to radiation, lymph nodes irradiated, and development of another mast cell tumor did not appear to influence median disease free interval or survival. Data presented herein support megavoltage radiation as an effective treatment for canine mast cell neoplasia, and suggest that disease free interval in dogs treated with daily fractions may be longer than that achieved with alternating day fractions.

Adrenal Cortex Hormones↗

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Factors influencing survival after radiotherapy of nasal tumors in 130 dogs.

Improvements in survival of dogs with nasal tumors have been slow to develop throughout the past three decades. Despite multiple studies examining various radiation time-dose schema, the advancement of CT-based computerized treatment planning, and the evaluation of detailed staging systems, the optimal treatment regimen, and most important prognostic factors regarding survival remain unclear. In this study, data from four previous studies were combined with data from 44 additional dogs, and this population of 130 dogs was evaluated for factors which influenced survival. Twenty-one dogs were treated with orthovoltage at the University of Pennsylvania. One hundred nine dogs were treated with cobalt photons at North Carolina State University. Sixty-five of these 109 dogs had been previously described. Of the 44 dogs not previously described, 35 were treated with a shrinking field technique. Survival was determined from the medical record, or from information derived by telephone or mail survey. The univariate Cox regression model was used to examine for relationship between various patient, tumor, and treatment variables and survival. Significant relationships identified in the univariate analysis were further analyzed using the multivariate Cox regression model. Median survival of the 130 dogs was 8.9 months (95% C.I., 8-11 months). In the univariate analysis, the following variables were associated with decreased survival: 1) age >10 years old, 2) regional lymph node metastasis, 3) advanced tumor stage, 4) use of megavoltage radiation, 5) overall total dose >55 Gray, and 6) boost technique performed. In a multivariate analysis of 125 dogs with complete data for age, radiation type, and radiation dose, age (p < .001) and radiation type (p = .02) were identified as joint predictors of survival. After adjusting for age, the staging system lost prognostic significance (p = .06). In a subset of dogs that received cobalt radiation, after adjusting for age, dogs treated with a boost technique had decreased survival (p = .001). In general, local control of canine nasal tumors following aggressive radiation therapy is poor. Early diagnosis and selection of appropriate patients is warranted and palliative types of treatment should be considered in dogs with a poor chance of long term survival.

Animals↗

PubMedDate not supplied

Hyperthermic modulation of radiolabelled antibody uptake in a human glioma xenograft and normal tissues.

These experiments investigate the biodistribution of radiolabelled MAb in a human glioma xenograft model after 4 h of local hyperthermia (HT) with a twofold purpose: to maximize the ratio of cumulative isotope activity in tumour relative to normal tissues, and to examine the temperature dependence of the effect. Restrained, unanaesthetized athymic nude mice bearing 150-200 mm3 s.c. human glioma xenografts (D-54 MG) were given 5 micrograms 125I-labelled specific and 131I-labelled non-specific MAb immediately prior to HT (water bath) for 4 h. Cohorts of five animals were killed at 0, 4, 8, 12 and 24 h after HT, and normal and tumour tissues were analysed for activity of each isotope. MAb uptake in tumour was greater with HT than with controls, and greater for specific MAb than for non-specific MAb. Uptake in thyroid was not significantly affected by tumour HT, suggesting that HT does not increase the rate of dehalogenation. Uptake in several other normal tissues away from the heated site was significantly increased (as were reported previously in mice anaesthetized with pentobarbital sodium during treatment; Cope et al. 1990), but the temporal pattern was different from that observed in tumour, suggesting that short-lived isotopes might lead to preferential dose deposition in heated tumour. Doses to various tissues were calculated for isotopes having a range of half-lives; the results clearly indicated that maximum differential in uptake between tumour and normal tissues would occur for isotopes with half-lives < 3 days. A separate series of experiments compared tumour uptake for 40, 42 and 44 degrees C HT. These results demonstrated that 42 and 44 degrees C HT created maximum enhancement in specific antibody uptake over controls. Specific MAb was retained over time in 42 degrees C-heated tumours, whereas significant washout occurred for non-specific MAb, which indicates that MAb retention was due to increased specific binding at this temperature and not vascular damage with antibody trapping. Retention of both specific and non-specific MAb was seen at 44 degrees C, suggesting that vascular damage becomes an important non-specific mechanism for antibody retention at higher temperatures.

Animals↗

PubMedDate not supplied

The effects of hyperthermia in bone marrow purging of breast cancer.

The number of autologous bone marrow transplants done for solid tumours, particularly breast cancer, has risen steadily over the last ten years. The role of bone marrow or peripheral blood progenitor cell purging in transplantation is incompletely understood. Theoretically, the reinfusion of untreated bone marrow containing tumour cells might result in relapse in some patients treated with high-dose chemotherapy and hematopoietic support. Therefore, safe and effective purging techniques may increase long-term, disease-free survivorship. In this study, hyperthermia was evaluated for its ability to purge CAMA-1 breast cancer cells from normal human bone marrow. Between two and nine trials of a range of temperatures (42-45 degrees C) and durations of treatment (1-4 h) were performed. The effect of hyperthermia on normal bone marrow alone and in mixes with breast cancer cells was also evaluated. Hyperthermia (45 degrees C, 4 h) produced > 5 logs of CAMA-1 cell kill. Exposures of 45 degrees C for 2 h and 44 degrees C for 4 h resulted in approximately three logs of cell kill, corresponding to < 1% survival of clonogenic cells. Normal bone marrow was considerably more vulnerable to heat treatments, however, with approximately 1% of progenitors remaining clonogenic after exposure of 43 degrees C for 2 h and 44 degrees C for 1 h. Therefore, although hyperthermia is able to achieve adequate CAMA-1 breast cancer cell kill, it remains more toxic to normal bone marrow as a purging method. To make hyperthermia useful in purging systems, mechanisms to selectively alter thermal sensitivity must be pursued.

Bone Marrow Purging↗

PubMedDate not supplied

A curricular model for a rural family practice clerkship.

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Curriculum↗