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R S Sedlacek

Publications and source records attributed to R S Sedlacek.

At least 19 recordsLinked to original sources
PubMed1991

A comparative study on the xenotransplantability of human solid tumors into mice with different genetic immune deficiencies.

These experiments set out to assess the role of NK and B cells in the resistance of nude mice to human tumor xenotransplantation. The transplantability of 9 fresh and 8 cultured human tumors was compared in 2 strains of mice with different genetic immune deficiencies: athymic NCr/Sed (nu/nu) nude mice, and nude-beige-xid (N:NIH-nu-bg-xid/Sed mice). Flow cytometric studies showed both strains to be deficient in Thy. 1.2 (T) cells and unresponsive to stimulation by Concanavalin A (Con A) or direct T-cell-receptor triggering with anti-CD3. The number of B cells was similar in the 2 strains, but the response to lipopolysaccharide (LPS) was markedly reduced in the nude-beige-xid animals. The number of asialoGM1-positive cells (predominantly NK) detected by flow cytometry was also reduced in the nude-beige-xid mice. The transplantability of the human tumors was found to be equivalent in the 2 strains. Quantitative cell-transplantation assays performed for 2 of the tumor cell lines did not reveal any subtle transplantation advantage for the more broadly immune-deficient animals. No evidence could, therefore, be found to suggest that NK or B cells were major determinants of human tumor xenotransplantability in these strains of mice.

Animals↗
PubMed1990

Residual immunity of athymic NCr/Sed nude mice and the xenotransplantation of human tumors.

This study assessed the residual immunity possessed by NCr/Sed (nu/nu) athymic nude mice and examined strategies to reduce it in order to enhance the transplantability of human tumors for experimentation. Adult (8-week-old) female mice had fewer T cells (11%) and more B and NK (asialo-GM1-positive [ASGM1+]) cells in their spleen than euthymic (nu/+) controls. The number of phenotypically mature T cells increased with age, peaking at 16 weeks. ASGM1+ cells also increased in number over time, although the NK-activity decreased after 12 weeks. B cells remained relatively constant in number. Athymic NCr/Sed nude mice displayed reactivity against a human squamous carcinoma xenograph (FaDu), in a Winn's test and TD50 assay. Immunity against xenografts (TD50 assay) was significantly lower (by a factor of 2) in 4-week-old than in 12-week-old nude mice. Similarly, a significant 2-fold reduction in TD50 was obtained after a single intraperitoneal injection of cyclophosphamide into 8-week-old animals. Chronic (greater than 8 weeks) exposure of the nude mice to subcutaneously administered beta-estradiol markedly reduced the number of splenic NK cells and their cytolytic activity, but the TD50 reduction was not statistically significant (p = 0.1). Six Gray whole-body irradiations (WBI) had been shown to produce a highly significant, 3-fold reduction in the TD50 for FaDu. Flow cytometric analysis of splenic lymphoid cells from whole-body-irradiated recipients revealed: (a) marked initial depletion in the absolute numbers of lymphoid cells; (b) marked and long-lasting depletion of T cells, with slow and minimal recovery only evident between 6 and 12 weeks; (c) rapid, almost complete, depletion of B cells with prompt and partial recovery after 2 weeks; (d) depletion of NK cells and NK activity, with recovery by 10 weeks. No change in the number or phagocytic capacity of resident peritoneal macrophages was seen. These data give further support to a postulated role for residual T cells in the xenoreactivity of NCr/Sed nude mice.

Age Factors↗
PubMed1990

The response of two human tumor xenografts to fractionated irradiation. The derivation of alpha/beta ratios from growth delay, tumor control, and in vitro cell survival assays.

A series of growth delay experiments was performed to derive alpha/beta ratios for two human neoplasms growing as xenografts in the hind limbs of NCr/Sed nude mice. The tumors were irradiated at 6 mm mean diameter under clamp-hypoxic conditions in one, two, four, or eight fractions, 2 fractions per day with a minimum intertreatment interval of 4 hr and a maximum overall treatment time of 3 days. The alpha/beta ratios derived for the high grade glioma U87 and the pharyngeal squamous carcinoma FaDu were 38 and 20 Gy, respectively. Comparably high values were derived from the same two tumors in a reanalysis of fractionated TCD50 data. The alpha/beta ratios were similarly high whether the TCD50 data were analyzed using the Full Effect plot or the Direct Method. For comparison, cell survival assays were performed on U87 and FaDu irradiated in vitro under plateau-phase, aerobic conditions. The alpha/beta ratios obtained were 9.2 and 15.0 Gy, respectively. Such high alpha/beta values suggest a therapeutic gain could result from the use of small doses per fraction.

Animals↗
PubMed1990

Metastases after fractionated radiation therapy of three murine tumor models.

The incidence of lung metastases after fractionated radiation therapy was compared to single dose irradiation in a retrospective analysis of three murine tumor models. For FSaII and SCCVII 5 or 15 fractions over 5 days were given using curative and subcurative doses and photons and neutrons. Data were pooled from different experiments. In mice with locally controlled FSaII the incidence of lung metastases was the same after all treatments, whereas in mice with locally controlled SCCVII, metastases were enhanced after 15 fractions. Photon and neutron irradiations yielded similar results. Local recurrences were followed by increased metastases. MCaIV was subcuratively irradiated with 9 equal fractions followed by a top-up dose to achieve local control. Metastases were high if doses per fraction were low and interfraction time intervals long. The data on MCaIV indicate increased metastases if clonogenic cells during treatment represent a large proportion of the integral tumor burden. The results on FSaII and SCCVII indicate that fractionated treatments might differently influence distant metastasis in different tumor models.

Animals↗
PubMed1988

Quantitative studies on the transplantability of murine and human tumors into the brain and subcutaneous tissues of NCr/Sed nude mice.

The transplantability of experimental tumors into the brain (i.c.) and s.c. tissues of C3Hf/Sed and athymic NCr/Sed nude mice was examined using quantitative cell transplantation assays. Studies using the immune-competent C3H animals showed that brain is a more favorable site for the transplantation of syngeneic tumor than s.c. tissue and that this is true for nonimmunogenic as well as immunogenic tumors. The capacity of the brain to act as an immunological sanctuary can be overwhelmed by a strong, systemic, secondary immune response such as that evoked by the methylcholanthrene-induced sarcoma FSal. In studies performed using NCr/Sed nude mice, the allogeneic tumor MCaIV was found not to be demonstrably immunogenic. The cell dose required to transplant the tumor into 50% of recipients (TD50) could neither be increased by immunization procedures nor decreased by six Gy whole-body irradiation (WBI) prior to transplantation. Delayed-type hypersensitivity to this tumor was not expressed by nude mice after rechallenge with tumor antigen. The TD50 was again lower for i.c. than s.c. transplantation and the ratio s.c./i.c. was comparable to that found in syngeneic C3Hf/Sed hosts. Three human tumors have been similarly tested. They were: FaDu, a pharyngeal squamous carcinoma; HFSal, a fibrosarcoma; and U87, a malignant glioma. s.c. TD50 values were in all cases significantly higher than those obtained i.c. The ratios TD50 s.c./i.c. ranged from 6.4 to greater than 50 in five studies, substantially higher than those found for transplantation of murine tumors into either the syngeneic or the allogeneic recipients. Six Gy WBI reduced the s.c. TD50 for these tumors, but in each case the value remained significantly higher than that obtained i.c. 19.4 Gy WBI given in 10 equal fractions and followed by i.v. bone marrow rescue reduced further the s.c. TD50 for FaDu. NCr/Sed nude mice demonstrated cross-reacting delayed-type hypersensitivity against FaDu and HFSal. A small proportion of FaDu tumors (less than 2%) displayed a spontaneous halt in growth or even regression. When the host cell infiltrate of these tumors was analyzed, an increase was seen in the proportion of Thy 1.2 and asialo-GM1-positive cells as compared with progressively growing tumors. These data strongly suggest that a residual low level of immune reactivity exists in nude mice against xenotransplanted human tumors. This resistance to s.c. transplantation may be diminished by WBI and is less for intracerebral implantation.

Animals↗
PubMed1988

Quantitative transplantation assays of spontaneous tumors of the C3H mouse as allografts in athymic NCr/Sed-nu/nu nude mice and isografts in C3Hf/Sed mice.

Three spontaneous tumors of the C3H mouse have been used in a comparison of their transplantability and radiation response (local control) in syngeneic C3Hf/Sed mice and in allogeneic athymic NCr/Sed-nu/nu nu nude mice. The tumors were: MCaIV, a moderately well-differentiated mammary carcinoma; FSaII, a poorly differentiated fibrosarcoma; and SCCVII, a moderately well differentiated squamous cell carcinoma. The tumors were studied as fourth to seventh generation transplants. Assays to determine the number of tumor cells that, on the average, transplant the tumor to half of the recipients or transplant sites (TD50) demonstrated that these 3 tumors transplanted into the s.c. tissue of the NCr/Sed-nu/nu as readily as of C3Hf/Sed mice. The TD50 for MCaIV was slightly but significantly lower in 4-week-old NCr/Sed-nu/nu mice which had received 6 Gy whole body irradiation (WBI) 24 h before transplantation, namely, 5.8 x 10(4) (95% confidence limits, 4.5-7.6) versus 7.8 x 10(4) (6.0-10.0). The 6-Gy WBI did not affect the TD50 for 8- to 10-week-old mice. Similarly, the TD50 for SCCVII was lower in 6-Gy WBI NCr/Sed-nu/nu recipients (1.5 x 10(4) versus 3.9 x 10(4)). The TD50 for FSaII was not affected by 6-Gy WBI. Further, the TD50 for FSaII following i.v. injection of tumor cells (transplant to lung) was the same for C3Hf/Sed and NCr/Sed-nu/nu mice (this obtained for normal or 6-Gy WBI-treated subjects). The radiation doses which on the average achieve control of half of the MCaIV, FSaII, and SCCVII tumors were lower, higher, and the same in NCr/Sed-nu/nu than in C3Hf/Sed mice, respectively. The radiation doses which achieve control of half of the MCaIV and SCCVII tumors were not affected by 6-Gy WBI before transplantation.

Animals↗
PubMed1985

Steam quality and effective sterilization.

Faced with using steam from a commercial utility having boilers greater than 5 miles distant and being the last user on the system resulted in ineffective sterilization. A three phase testing program was established utilizing: Direct physical measurements - an Ellison model 915A portable steam calorimeter. Direct microbiology - Autoclaved feed pellets were aseptically placed in fluid thioglycolate medium and incubated at 37 degrees C. Indirect microbiology - Feces from "defined flora" mice fed the autoclaved pelleted feed were tested. Colorimetric measurements verified that the steam sometimes contained greater than 5% entrained water. During periods of wet steam it was impossible to maintain consistent sterility of the mouse pellets even using a cycle of 126 degrees C for 60 minutes. One spore-forming Gram positive rod, Clostridium perfringens type D was the predominant bacterium isolated. Lactating mice, or mice stressed experimentally came down with diarrhea within days of eating pellets treated with wet steam (calorimetric measurements) and a subsequent positive culture. These mice voided stools predominantly showing Clostridium perfringens type D.

Animals↗
PubMed1985

Pentobarbital anesthesia and the response of tumor and normal tissue in the C3Hf/sed mouse to radiation.

Studies of the effect of pentobarbital anesthesia on the radiation response have been performed using early generation isotransplants of three spontaneous tumors of the C3H mouse: a mammary carcinoma (MCaIV), a fibrosarcoma (FSaII), and a squamous cell carcinoma (SCCVII). The enhancement ratio of pentobarbital [ER(PB)] for TCD50 as the end point was greater than or equal to 1 for all conditions tested. The ER(PB) for O2 3 ATA conditions and two equal doses was 1.46, 1.72, and 2.21 for MCaIV, FSaII, and SCCVII, respectively. The ER(PB) using MCaIV was the same for O2 and carbogen at 1 or 3 ATA. Also, tumor size of MCaIV did not significantly affect the ER(PB) for O2 3 ATA conditions. Further, with the two-dose protocol the anesthesia and the hyperbaric oxygen needed to be used at the second dose; condition at the first dose was not critical. For fractionated irradiation of MCaIV (10 and 15 equal doses) the ER(PB) was smaller than for two-dose treatment; also the effect was less for intratumor temperature of 35 degrees C than 26-27 degrees C. There was no effect of the anesthesia on the acute response of normal skin of the leg. Lung damage by hyperbaric oxygen was not an important factor in these results. Additionally, ERs were computed for O2 at 3 ATA. This ER(O2 3 ATA) was larger for anesthesized than conscious mice. The ER(O2 3 ATA) for MCaIV was high (greater than 1.5) even for radiation given in 10 or 15 equal doses.

Anesthesia↗
PubMed1983

Experimental condition and the acute reaction of mouse skin to ionizing radiation.

The acute reactions of skin of the thigh-leg of normal young adult C3Hf/Sed mice following five equal radiation doses (60Co) were studied in mice irradiated at various leg skin temperatures and while respiring various gas mixtures in control or anesthetized condition (sodium pentobarbital, 0.05 mg/g-1 body wt.) At 25 and 35 degrees C, anesthesia reduced the RD50 (2.5+ reaction) by 4-5%. An increase of temperature from 25 to 35 degrees C resulted in a decrease in RD50 by 10-12% for subjects respiring air or 5% for subjects respiring O2 at 1 or at 3 ATA. The major modifier of radiation response was to change from respiration of air to O2 at 1 or 3 ATA. Enhancement ratios for RD50 Air/O2 1 ATA were 1.4-1.5 for 25 and 35 degrees C. The ratios O2 1 ATA/3 ATA were 1-1.05.

Anesthesia↗
PubMed1979

Enhancement of the thermal response of animal tumors by Corynebacterium parvum.

The effect of Corynecbacterium parvum treatment on the thermal response of animal tumors was studied. Tumors were methylcholanthrene-induced (FSa-II) and spontaneous (FSa-I) fibrosarcomas in C3Hf/Sed mice. C. parvum was given i.v. and was followed by local hyperthermia at 43.5 degrees 3 days later. Cell survival determined by lung colony assays showed that preadministration of C. parvum insignificantly enhanced the thermal response of both tumors. Studies of delay of tumor growth for FSa-II demonstrated that the enhancement ratio decreased with increasing time of treatment and reached a minimum of approximately equal to 1.7. The enhancement ratio for the time at hyperthermia which achieved tumor control in one-half of the treated tumors was 1.7. Together with our previous results on normal tissue responses, the therapeutic gain factor for obtaining 50% tumor control was found to be 1.1 (1.7/1.55) for the weekly immunogenic FSa-II tumor, while it was 2.3 for moderately immunogenic FSa-I as reported previously.

Animals↗
PubMed1977

A simple and inexpensive method for maintaining a defined flora mouse colony.

The use of autoclaved cages, feed, bedding, water, and filter caps combined with aseptic techniques of animal husbandry in an existing mouse colony was ineffective in maintaining a defined flora colony. The addition of a laminar air flow bench equipped with a high efficiency particulate air filter provided a sterile environment in which to manipulate mice when the filter caps were removed. The installation of a duct to direct all air entering the room through the bench filter reduced the airborne bacterial counts in the room. This modification combined with the culling or marking of infected cages so that no future breeders would be taken from these cages eliminated a number of bacterial contaminants (Staphylococcus aureus, S epidermidis, and streptococci) from the colony.

Air Microbiology↗
PubMed1976

Radiation therapy and Corynebacterium parvum in the treatment of murine tumors.

The relative effectiveness of local irradiation alone or combined with Corynebacterium parvum (C parvum) treatment has been investigated employing four tumors: a mammary carcinoma (MCa) (nonimmunogenic), a fibrosarcoma (moderately strongly immunogenic), and two squamous cell carcinomas (SCC-2 being weakly and SCC-4 being very weakly or nonimmunogenic). C parvum treatment was started when the isotransplanted tumor growing in the mouse leg was 5 mm in diameter and the local irradiation was administered to 8-mm diameter tumor. Effect of the combined treatment was barely evident with the MCa but strongly present in FSa; up to 60% of mice were cured of FSa by C parvum alone and the response to low radiation dose, e.g., 200 rads, was highly increased. For SCC-2 the TCD50 was approximately 7000 rads and 3000 rads in control and test mice, respectively. Comparable values for SCC-4 were 7700 and approximately 5500 rads. Importantly, for SCC-4 there was a large and highly significant reduction in the proportion of mice that died of metastases to lung but were free of evident tumor at the primary site.

Animals↗