Oxytocin administered centrally facilitates formation of a partner preference in female prairie voles (Microtus ochrogaster)

Prairie voles (Microtus ochrogaster) are monogamous mammals that form male-female pair bonds. Partner preference formation, one component of the pair bond in prairie voles, occurs following male-female cohabitation and is facilitated by mating. The peptide hormone oxytocin is released during physical contact and particularly following vaginal stimulation. Oxytocin has been implicated in mother-infant bond formation. The present study tested the hypothesis that oxytocin participates in the partner preference component of pair bond formation in adult prairie voles. Ovariectomized female prairie voles were implanted with osmotic mini-pumps releasing oxytocin (1-100 ng/h) or artificial cerebrospinal fluid (CSF). Pumps were implanted intracerebroventricularly or subcutaneously and females then were housed for 6 h with a male partner, followed by a preference test in which females could elect to spend time with either the partner or an unfamiliar male. Females in groups that received centrally-administered oxytocin (10 or 100 ng/h), but not CSF, exhibited a significant preference for the partner present during infusion. The induction of a partner preference after oxytocin administration appeared specific for central oxytocin pathways as peripheral oxytocin administration was ineffective. Moreover, central administration of a selective oxytocin receptor antagonist inhibited the behavioral effect of exogenous oxytocin. These results suggest that oxytocin may be one factor contributing to the development of partner preferences in this monogamous rodent.

The effect of polyamine depletion on the cytotoxic response to PUVA, gamma rays and UVC in V79 cells in vitro

Difluoromethylornithine (DFMO) depletes cells of polyamines, sensitizing cells against the action of antineoplastic drugs and altering ability to repair radiation-induced DNA strand breaks. Others have hypothesized that the mechanism by which polyamine depletion sensitizes cells is through inhibition of DNA strand break repair or through altering the spectrum of initial DNA damage. We have compared the effect of polyamine depletion on cytotoxic effects in V79 cells for three agents that damage DNA: PUVA (8-methoxypsoralen and ultraviolet light, 365 nm), gamma-rays and UVC (ultraviolet light, 254 nm) in polyamine depleted V79 cells. DFMO pretreatment sensitizes cells to PUVA and gamma-ray toxicity but not to UVC. Unlike UVC photoinduction of DNA lesions, PUVA- and gamma-ray-induced DNA damage is modulated by chromatin structure. Our results suggest that polyamine depletion sensitizes cells to the action of PUVA and gamma-rays by mechanisms disparate from those for UVC, suggesting that the level or type of initial damage, rather than DNA repair, per se, may be the more important determinant of enhanced cytotoxicity.

Olfactory bulbectomy decreases social behavior in male prairie voles (M. ochrogaster)

Prairie voles (Microtus ochrogaster) are social rodents that show characteristics of monogamy including high levels of social behavior and male parental care. Behavioral studies of prairie voles have implicated chemosignals in the control of various components of social behavior and reproduction. In the present study, the role of the olfactory system in male behavior was examined following surgical removal of the olfactory bulbs. Decreases in measures of sexual, paternal, and other social behaviors were observed following bilateral olfactory bulbectomy, but not unilateral or sham bulbectomy. Some bilaterally bulbectomized males also showed a stereotypy, but this probably did not account for the changes in social behaviors.

Comparison of spiral-acquisition computed tomography and conventional computed tomography in the assessment of pulmonary metastatic disease

In a prospective study, spiral-acquisition computed tomography (SACT) of the thorax was evaluated in 104 patients with extrathoracic malignancy and suspected pulmonary metastases, and was directly compared with conventional computed tomography (CCT) in 23 patients. The following parameters were assessed: lesion detectability; the effect on lesion detectability of reconstruction of scans at 5 mm and 10 mm slice increments; breathing artefact and slice misregistration. The radiation dose of the two techniques was measured using thermoluminescent dosimeters placed within an anthropomorphic chest phantom, and the visibility of simulated metastases inserted into the phantom was also compared using CCT, standard SACT and SACT with pitch greater than 1.0. Where metastases were present, SACT scans showed significantly better lesion detectability than CCT scans (p < 0.001). Image reconstruction of SACT data at 5 mm increments conferred no significant advantage in lesion detectability over 10 mm increment reconstructions. Compared with CCT, SACT scans showed reduced breathing artefact, and a complete absence of slice misregistration (p < 0.01). Phantom measurements of radiation dose and resolution were similar for both techniques. Increasing the pitch of the spiral in SACT caused only a small decrease in phantom resolution, but with the advantage of a reduction in the radiation dose. Spiral-acquisition CT is superior to conventional CT for the assessment of pulmonary metastatic disease.

Effect of tumor irradiation on the uptake of lymphokine-activated killer cells in a murine tumor model

Immunotherapy with lymphokine-activated killer (LAK) cells and interleukin 2 is one of the newer treatment modalities for cancer. This raises important questions concerning synergism or suppressive effects of other existing treatment modalities on adoptive immunotherapy with LAK cells. A tumor model with H4IIe hepatoma cells grown on each flank of ACI rats was developed to evaluate the effect of external beam irradiation of tumors on the subsequent concentration of LAK cells in these tumors. Tumors on one side were irradiated at 6, 12, or 16 Gy prior to injection of [3H]thymidine-labeled LAK cells. The effect of irradiation was measured as the ratio of 3H recovered in the unirradiated tumor compared to that in the irradiated tumor in the same animal as a function of dose and time after irradiation. This ratio was significantly greater than 1.0 for a radiation dose of 12 Gy (2.35 +/- 0.51) measured 2 days after irradiation, indicating a reduction in LAK cell numbers in the irradiated tumor. This reduction in LAK cell number persists up to at least 4 days following radiation exposure. A similar experiment using 125I-labeled interleukin 2 showed equal distribution in the irradiated and unirradiated tumors. Our data demonstrates that the concentration of LAK cells is markedly reduced by prior radiation, in contradistinction to increased uptake of immunoglobulins in irradiated tumors, as shown by others. If a similar reduction is observed for longer duration after radiation exposure, it might suggest a clinically important interaction between prior radiation exposure and adoptive immunotherapy.

Characterizing soils for hazardous waste site assessments

This paper provides a review and justification of the minimum data needed to characterize soils for hazardous waste site assessments and to comply with the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Scientists and managers within the regulatory agency and the liable party need to know what are the important soil characteristics needed to make decisions about risk assessment, what areas need remediation and what remediation options are available. If all parties involved in characterizing a hazardous waste site can agree on the required soils data set prior to starting a site investigation, data can be collected in a more efficient and less costly manner. Having the proper data will aid in reaching decisions on how to address concerns at, and close-out, hazardous waste sites.This paper was prepared to address two specific concerns related to soil characterization for CERCLA remedial response. The first concern is the applicability of traditional soil classification methods to CERCLA soil characterization. The second is the identification of soil characterization data type required for CERCLA risk assessment and analysis of remedial alternatives. These concerns are related, in that the Data Quality Objective (DQO) process addresses both. The DQO process was developed in part to assist CERCLA decision-makers in identifying the data types, data quality, and data quantity required to support decisions that must be made during the remedial investigation/feasibility study (RI/FS) process. Data Quality Objectives for Remedial Response Activities: Development Process (US EPA, 1987a) is a guidebook on developing DQOs. This process as it relates to CERCLA soil characterization is discussed in the Data Quality Objective Section of this paper.

An audit of the effect of a 24-hour emergency operating theatre in a district general hospital

The recent introduction of a 24-hour emergency theatre for General Surgery provided an opportunity to audit its effect on emergency operating in a District General Hospital. Prior to its introduction much of the emergency operating was determined by theatre availability rather than clinical need. Half of the emergency operations were carried out between 10 pm and 8 am. This proportion was reduced to a third when a theatre was continually available. This had benefits for the patients in reducing their waiting time and also for the junior surgeons by increasing their sleep. A survey of the Region indicated that very few hospitals provided adequate emergency theatre facilities.

Use of bremsstrahlung radiation to monitor Y-90 tumor and whole body activities during experimental radioimmunotherapy in mice

BACKGROUND

Large differences in uptake between tumors, even for the same size, frequently observed in clinical and experimental radioimmunotherapy (RAIT), make monitoring of uptake in individual tumors imperative in comparing protocols. 90Y, widely-used for RAIT, emits no gamma radiation and absorption of the beta particle in tissue makes its detection unsuitable for in vivo monitoring. We tested whether bremsstrahlung radiation, produced when betas are decelerated by nuclei, could be used to monitor tumor uptake.

METHODS

Subcutaneous human LS174T colon carcinoma tumors were grown in the upper thigh of nude mice and labeled antibody injected intracardially. With the tumor placed in the 2 cm-diameter aperture in a lead collimator, photons with energies from 100 to 200 keV transmitted through plastic, which absorbed the beta particles, were counted to maximize shielding from the rest of the body. The contribution of the normal tissues was subtracted by counting the non-tumor-bearing leg in the same position. Excretion was calculated from whole body activity determined by removing the collimator, placing the mouse in a syringe surrounded by tissue-equivalent material 10 cm from the detector, and counting photons between 200 and 740 keV to minimize the effect of tissue attenuation.

RESULTS

For tumors larger than 0.14 gm, a good correlation was obtained between the in vivo bremsstrahlung measurements and the measurements on excised tumors in a calibrated well counter. Similar excretion rates observed in all the animals suggested that the whole body counting was accurate.

CONCLUSIONS

Bremstrahlung detection appears feasible and reliable for monitoring both tumor and whole body activities.

A new method for determining dose rate distribution from radioimmuno-therapy using radiochromic media

PURPOSE

To describe and evaluate a new, simple, inexpensive method for directly measuring the radiation dose and its spatial distribution generated from explanted tissues of animals previously injected with radiolabeled immunoconjugates or other agents.

METHODS AND MATERIALS

This technique uses the newly developed radiochromic dye medium (Gafchromic) which responds reproducibly for therapeutic dose exposures, has high spatial resolution, does not require film processing, and is relatively insensitive to ambient light. We have evaluated the dose distribution from LS174T tumors and selected normal tissues in nude mice previously injected with 90Y labeled anti-carcinoembrionic antigen antibodies. Individual tissues from sacrificed animals are halved and the flat section of the tissue is placed onto the dosimetry media and then frozen. The dosimetry medium is exposed to beta and Bremsstrahlung radiation originating from the frozen tissues. The relative darkening of the dosimetry medium depends on the dose deposited in the film. The dosimetry medium is scanned with a commercial flatbed scanner and the image intensity is digitally stored and quantitatively analyzed. Isodose curves are generated and compared to the actual tissue outline.

RESULTS

The absorbed dose distribution due to 90Y exposure show only slight gradients in the interior of the tissue, with a markedly decreasing dose near the edges of the tissue. In addition, the isodose curves follow the tissue outline except in regions having radii of curvature smaller than the range of the beta-particle (R90 = 5 mm). These results suggest that the shape of the tumor, and its curvature, are important in determining the minimum dose delivered to the tumor by radiation from 90Y monoclonal antibodies, and hence in evaluating the tumor response to the radiation. The dose and spatial dose distribution were calculated assuming that the total 90Y activity is distributed uniformly throughout a half ellipsoid. The calculated spatial dose distributions for the half ellipsoids were similar to those observed from the dosimetry media that had been exposed to radioactivity contained in the tumors.

CONCLUSION

This method provides direct dose evaluation without elaborate summary calculations based on activity measurements from serial slices. The measured radiation dose actually indicates the dose rate at the time of animal sacrifice. Quantitative analysis of radiation emitted from the tissues is relatively fast, making it feasible to examine a number of tissues under a variety of conditions.

Assessment of radiolabeled stabilized F(ab')2 fragments of monoclonal antiferritin in nude mouse model

The biodistribution of 111In-labeled stabilized fragments of monoclonal antiferritin was studied in nude mice bearing a human hepatoma tumor xenograft. Pharmacokinetics and tumor targeting of fragment Fab'-linker-Fab' fragment molecules (stabilized F(ab')2) were compared to unmodified F(ab')2 fragment molecules and immunoglobulin G (IgG). Significant differences were observed in tumor and normal organ uptake at 12, 24, 48 and 72 hr. Tumor retention of stabilized F(ab')2 fragments was approximately 2.5-fold higher than of unmodified F(ab')2 at 48 hr. Blood clearance for stabilized F(ab')2 was relatively faster than intact IgG, while unmodified F(ab')2 cleared more rapidly from the circulation. Kidney radioactivity of unmodified F(ab')2 was at least two times higher than kidney radioactivity of stabilized F(ab')2 at all time points. Stabilized F(ab')2 demonstrated 40% less liver uptake than intact IgG. In these studies with nude mice, substantial retention of stabilized F(ab')2 in tumor and significant reduction in liver and kidney uptake of these fragments indicated that they could also have a higher therapeutic ratio than IgG or unmodified F(ab')2 in human patients.

Degradation fragments of L1 antigen enhance tyrosine hydroxylase-immunoreactive neurite outgrowth in mesencephalic cell culture

The L1 antigen has been implicated in adhesion events controlling axonal elongation during formation of major fiber tracts, and promotes neurite outgrowth in culture. It is possible that injury of brain tissue causes neuronal surface molecules such as L1 antigen to be shed, and degradation fragments may therefore be present adjacent to the damage. These L1 fragments might then influence regeneration or injury-induced growth. We have evaluated neurite outgrowth from tyrosine hydroxylase-positive (TH +) E13 mesencephalic neurons grown in vitro on a substrate of mouse L1 antigen and on L1 degradation fragments separated by molecular weight. Mouse myelin-associated glycoprotein (MAG), laminin, poly-D-lysine, and fetal calf serum served as control substrates. L1 antibodies were added to one set of cultures (experimental), and compared to control cultures containing normal rabbit serum. After 3 days in vitro, the cultures were stained using an antibody against TH, and the length of the TH + neurites was measured by computer-assisted image analysis in a double-blind fashion. TH+ neurites were significantly longer when grown on L1 antigen, as well as on L1 degradation fragments, as compared to the control substrates. As compared to control normal rabbit serum, L1 antibodies eliminated the neurite-promoting effect of both the L1 substrate and the L1 degradation products. In addition, L1 substrates promoted clustering of TH + cells and the formation of loose bundles of TH + neurites. It is suggested that the L1 substrates influence TH-immunoreactive neurite outgrowth, at least partially, through indirect effects on glial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper-resistant enteric bacteria from United Kingdom and Australian piggeries

Thirty-three enteric isolates from Australian (Escherichia coli only) and United Kingdom (U.K.) (Salmonella sp., Citrobacter spp., and E. coli) piggeries were characterized with respect to their copper resistance. The copper resistance phenotypes of four new Australian E. coli isolates were comparable with that of the previously studied E. coli K-12 strain ED8739(pRJ1004), in that the resistance level in rich media was high (up to 18 mM CuSO4) and resistance was inducible. Copper resistance was transferable by conjugation from the new Australian isolates to E. coli K-12 recipients. DNA similarity between the new Australian isolates and the pco copper resistance determinant located on plasmid pRJ1004 was strong as measured by DNA-DNA hybridization; however, the copper resistance plasmids were nonidentical as indicated by the presence of restriction fragment length polymorphisms between the plasmids. DNA-DNA hybridization and polymerase chain reaction analysis demonstrated DNA homology between the pco determinant and DNA from the U.K.E. coli, Salmonella sp., and Citrobacter freundii isolates. However, the copper resistance level and inducibility were variable among the U.K. strains. Of the U.K. E. coli isolates, 1 demonstrated a high level of copper resistance, 4 exhibited intermediate resistance, and 16 showed a low level of copper resistance; all of these resistances were expressed constitutively. A single U.K. C. freundii isolate, had a high level of copper resistance, inducible by subtoxic levels of copper. Transconjugants from one E. coli and one C. freundii donor, with E. coli K-12 strain UB1637 as a recipient, showed copper resistance levels and inducibility of resistance which differed from that expressed from plasmid pRJ1004.(ABSTRACT TRUNCATED AT 250 WORDS)

Preclinical evaluation of intravenously administered 111In- and 90Y-labeled B72.3 immunoconjugate (GYK-DTPA) in beagle dogs

B72.3, a monoclonal antibody with reactivity against human adenocarcinomas was obtained from the Cytogen Corporation in the form of an immunoconjugate coupled with linker-chelator GYK-DTPA by using proprietary carbohydrate directed site specific chemistry. The immunoconjugate was radiolabeled with indium-111 or yttrium-90. A preclinical analysis was performed in 10 normal beagle dogs. The pharmacokinetics of intravenously administered indium- and yttrium-labeled immunoconjugates were compared serially in blood, bone marrow and urine samples. Compared to 90Y less of the 111In label ended up in urine and more was found in blood and bone marrow. Indium-labeled B72.3 GYK-DTPA had relatively higher uptake in most glandular tissues than 111In-labeled antiferritin immunoconjugate. Bone marrow toxicity was the dose limiting side effect after intravenous infusion of 90Y-labeled B72.3 GYK-DTPA. Toxicity was also observed in the liver but not in other organ systems. Recently other investigators obtained similar results with these immunoconjugates in human patients. A preclinical pharmacokinetic analysis of radioimmunoconjugates in beagle dogs provided useful information regarding bone marrow toxicity, liver toxicity and in vivo instability of the immunoconjugate. Data suggest that for future trials in human patients, a more stable chelated immunoconjugate for yttrium is needed to achieve less liver uptake and a better correlation with the 111In-labeled product than the 90Y-labeled B72.3 GYK-DTPA used in this investigation.

Fractionated intravenous administration of 90Y-labeled B72.3 GYK-DTPA immunoconjugate in beagle dogs

B72.3, a monoclonal antibody with reactivity against human adenocarcinomas, was coupled with linker-chelator GYK-DTPA using carbohydrate mediated conjugation chemistry and radiolabeled with yttrium-90. Single and double intravenous injections of radioimmunoconjugate were compared for acute and late normal tissue toxicity in 15 beagle dogs. The second injection was given 4 or 8 days after the first. Pharmacokinetics of the radioimmunoconjugate in blood, bone marrow and urine were similar for first and second injections. Only bone marrow (acute) and liver (late) toxicity were observed. Both liver and bone marrow toxicity were decreased by fractionation of the injections. After double injections, the total equitoxic dose was 15 and 60% higher for bone marrow and liver toxicity, respectively. The mechanisms of normal tissue protection offered by fractionated radioimmunoglobulin therapy (RIT) remain to be defined. Fractionated RIT will have a better therapeutic ratio than single injection RIT, if antitumor effects appear to be less susceptible to fractionation than normal tissues.

Evaluation of indium-111- and yttrium-90-labeled linker-immunoconjugates in nude mice and dogs

Rapid uptake and slow transit of radioactivity from normal organs are detrimental to any clinical utilized radioimmunoconjugate because they lower the target-to-nontarget ratio and deliver undesirable radiation to normal organs. To mitigate this problem, two labile chemical linkages (EGS and DST) were introduced between a monoclonal antiferritin antibody (QCI) and a chelating agent (DTPA). The biodistribution of labile-linker immunoconjugates (EGS and DST) and stable linker immunoconjugates (DSS and ITCB) were compared. In a nude mouse model, all of the four immunoconjugates labeled with 111In targeted subcutaneously-implanted human tumor cells. Tumor-to-normal organ ratios were enhanced for the EGS linkage in comparison to the two stable linkages. Serial whole-body immunoscintigraphy confirmed the biodistribution study. The EGS and ITCB 90Y-labeled immunoconjugates had biodistributions similar to their respective 111In-labeled immunoconjugates. As the mouse model is not representative of the high uptake of monoclonal antibodies in the human liver, beagle dogs were used to further explore the retention of radiolabel in normal liver. The EGS-linked immunoconjugate significantly reduced the dog liver activity when compared to the ITCB immunoconjugate. The combination of the animal models (mouse and dog) appears to allow for a more compete and optimal preclinical analysis of chelated radiolabeled monoclonal antibodies for diagnosis or treatment and illustrates the potential clinical improvements possible with labile chemical linkages in radioimmunoconjugates.

Characterization of a New York ovine lentivirus isolate

A lentivirus has been isolated from a Finnish ewe with ovine progressive pneumonia in a closed upstate New York flock. We demonstrated that the virus, designated ovine lentivirus strain CU1 (OLV-CU1), is biologically, biochemically and molecularly related to, but distinct from, previously described sheep and goat lentiviruses. Nine of 32 ewes (from the affected flock) with precipitating antibodies for ovine lentivirus also produced antibodies that were able to neutralize the infectivity of OLV-CU1. The virus replicated in cultured sheep fibroblasts and caused the formation of large multi-nucleated cells. OLV-CU1-specific RNA transcripts found in infected cells and virion antigenic proteins were similar to those of other small ruminant lentiviruses. However, the virus was distinguished from other isolates at the DNA level by nucleic acid hybridization, restriction endonuclease mapping and partial sequencing of the virus genome.

The impact of preconception counseling on pregnancy outcomes. The experience of the Maine Diabetes in Pregnancy Program

OBJECTIVE

To determine if a noncentralized, statewide program could be established to educate health-care providers and women with pregestational diabetes on available strategies to prevent adverse outcomes in pregnancies complicated by diabetes. Characteristics of women who participated in the program and the outcomes of their pregnancies are evaluated.

RESEARCH DESIGN AND METHODS

A network of regional providers caring for pregnant women with diabetes was developed. Continuing education sessions were delivered to both providers and women with existing diabetes on the importance of preconception counseling.

RESULTS

Maine health-care providers collaborated on the development and adoption of three patient-care guidelines that address preconception counseling, prenatal care, and contraception for women with established diabetes. A total of 185 pregnancies among 160 women with pregestational diabetes reporting estimated delivery dates between 1 January 1987 and 31 December 1990 were identified. Of the total pregnancies, 62 (34%) occurred in women who received preconception counseling: among these 62 pregnancies were one major congenital defect (1.6%) and four fetal or neonatal deaths (6.4%). Among the 123 (66%) pregnancies occurring in women that had not received preconception counseling, 8 (6.5%) infants were born with congenital abnormalities, and 26 (21.1%) fetal or neonatal deaths were documented.

CONCLUSIONS

A program promoting preconception counseling can be implemented on a statewide basis by using various health-care providers to deliver the program. Participation in such a program appears to be related to improved pregnancy outcomes among women with pregestational diabetes.

Factors modulating preferences of female house mice for males differing in t-complex genotype: role of t-complex genotype, genetic background, and estrous condition of females

The present study investigates factors mediating odor and social preferences in female house mice (Muc domesticus) based on the t-complex genotype of males. Previous studies in this laboratory showed that females prefer the odors of wild-type (+/+) males over those that carry lethal genes (+/t). The purpose of this study was to determine the genetic, hormonal, and environmental factors that regulate these preferences. The variables examined include t-complex genotype, genetic background, estrous condition of test females (+/+ or +/t), and genotype of the test female's parents. Results indicate that female preferences for +/+ males are dependent upon the t-complex genotype and estrous condition of test females. Only +/t females in estrus showed preferences for +/+ males. Estrous cycle condition effects were seen in both wild (+/+w5) and inbred (129 +/tw5)females. Homozygous females (+/+) and diestrous females of both genotypes did not demonstrate preferences for either +/+ or +/t males.