A canine model of familial mammary gland neoplasia

Intact female Beagles from life-span studies in the Lovelace Respiratory Research Institute colony were examined for mammary tumor incidence. The breeding colony, founded in 1963, produced five generations from 28 founder females. After proportional hazards analysis, two maternal families were shown to have markedly different phenotypes, one susceptible and one resistant to mammary neoplasia, as compared with the entire colony. When tumors were subdivided into benign and malignant based on local invasiveness, familial differences in tumor incidence were preserved for each tumor type. Fifty-seven females in the susceptible family developed 149 benign and 39 malignant tumors, and 95 females in the resistant family developed 70 benign and 20 malignant tumors. The ratio of benign to malignant tumors of about 4:1 for both families was higher than expected. Using Kaplan-Meier and log-rank analyses, the susceptible family had a 50% malignant tumor incidence by age 13.6 years, whereas the resistant family did not have a 50% incidence until 17.0 years (P = 0.0065). Because of marked censoring, Kaplan-Meier analyses could not provide an estimate of the 50% benign tumor incidence; mean incidence age was calculated instead. These estimates for benign tumors for susceptible and resistant families were 10.8 and 13.8 years (P = 0.0001), respectively. Using chi(2) tests, families had no differences in the occurrence of the types of benign (P = 0.098) or malignant (P = 0.194) tumors or in the ratio of benign to malignant tumors (P = 0.778). Immunohistochemical analysis of malignant tumors from both families did not demonstrate differences in p53 mutation rate or p185erbB-2 expression. These results suggest that 1) genetic factors produce familial differences in the age of onset of both benign and malignant mammary tumors; histologic types do not segregate by family; 2) the ratio of benign to malignant tumors is greater than formerly reported; and 3) neither p53 nor p185erbB-2 alterations are the basis for the familial predisposition.

[Use of a fast test to detect rotavirus in feces]

The commercially available immunoassay "OnSite Rotavirus" was used for the detection of animal rotaviruses in 113 faecal samples. The sensitivity of the test was 88% and the specificity 96% compared with reference methods (EIA, EM). This test would detect approximately 4.4 x 10(6) to 1.8 x 10(7) virus particles per ml. The presence of virus could be demonstrated in fresh faecal samples from cattle, horses and pigs within a few minutes. The rotaviruses of group A were identified independently of the virus serotype. Further results and additional problems of using this test kit are described.

The developmental potential of the human oocyte is related to the dissolved oxygen content of follicular fluid: association with vascular endothelial growth factor levels and perifollicular blood flow characteristics

Regardless of whether fertilization occurs in vivo or in vitro, a large proportion of human embryos do not develop progressively through the pre-implantation stages or arrest development after implantation. This study examined the association between the chromosomal/spindle normality of the mature human oocyte and the dissolved oxygen content, vascular endothelial growth factor concentration (VEGF) and perifollicular blood flow characteristics of the corresponding ovarian follicles. Findings from >1000 samples of follicular fluid show that developmentally significant differences in dissolved oxygen content occur in follicular fluids aspirated from follicles of equivalent size and ultrasonographic appearance. Oocytes from severely hypoxic follicles were associated with high frequencies of abnormalities in the organization of the chromosomes on the metaphase spindle that could lead to segregation disorders and catastrophic mosaicisms in the early embryo. Oocytes with cytoplasmic defects and cleavage stage embryos with multinucleated blastomeres are derived predominantly from severely hypoxic follicles. VEGF measurements of follicular fluid and colour pulsed Doppler ultrasonographic analysis of follicle-specific blood flow characteristics indicated a potentially important role for this factor both in perifollicular angiogenesis and in the regulation of intrafollicular oxygen levels. The results are discussed with respect to how severe intrafollicular hypoxia may influence the normality of chromosomal organization and segregation in the oocyte, and whether detailed pulsed Doppler analysis of individual pre-ovulatory follicles may provide an indirect indication of the 'health' of the follicle and possibly the developmental competence of the corresponding oocyte.

[Measurement of the distance of the rectal mucosa from a gynecologic afterloading applicator based on the drop in performance of a cobalt-60-source]

PURPOSE

Assessment of the distance from a gynecological afterloading applicator to the rectum mucosa.

METHODS

The appropriate afterloading applicator for HDR-Ir-therapy is used for that purpose. A Co-60-source (370 MBq) with a guiding wire is positioned at the tip of the applicator and then withdrawn in steps of 1 cm. For each of these points the maximum dose at the rectum mucosa is measured with an ionisation chamber. From a reference curve it is then possible to determine the distance from the rectum mucosa to the applicator and to mark it in the calculated isodose plan. The actual daily dose to the rectum mucosa is planned not to exceed 3.0 Gy in the maximum.

RESULTS

Up to now the measurements were performed in 91 patients. The minimal distances of the rectum mucosa from the applicator were found to range from 5 to 18 mm with an average value of 14 mm.

CONCLUSIONS

The comparison of the measurement with the readings of the rectum probe during each session showed, that the method is suitable to avoid an overdose at the rectum mucosa.

[Stomatological identification after air disasters]

The paper describes experiences of stomatological identification after two air disasters and shows potentialities and limits of an odontologic(al) comparison. The application of a 16-bit-computer is pointed out as the essential improvement of the work.

[Dose distribution of pendulum fields in the field border plane]

Calculations (program SIDOS-U2) and LiF measurements taken in a cylindric water phantom are used to investigate the isodose distributions of different pendulum irradiation methods in a plane which is parallel to the central ray plane and crosses the field borders at the depth of the axis. The dose values compared to the maximum values of the central ray plane are completely different for each pendulum method. In case of monoaxial pendulum methods around small angles, the maximum dose value found in the border plane is less than 50% of the dose in the central ray plane. The relative maximum of the border plane moves to tissues laying in a greater depth. In case of bi-axial methods, the maximum value of the border plane can be much more than 50% of the maximum dose measured in the central ray plane.

[Effect of satellite supports of different materials on the surface dose in telecobalt therapy]

The surface doses were measured behind shield supports of different materials with a focus-skin distance of 140 cm. The shield supports were at a distance of 40 cm from the skin. The plates were made of lead glass with a thickness of 11.3 mm, window glass with a thickness of 2.6 mm, plexiglas with a thickness of 5 and 10 mm, and perforated plexiglas with a thickness of 6 mm. The greatest contamination of the useful ray with secondary electrons was measured behind the plexiglas plates, the least contamination was measured behind the plate of lead glass. The relative surface dose is increased by at most 18.5% by plates of plexiglas, while the lead glass plate causes an increase of 3.3%.

[Dosage of conservative therapy of the mammary carcinoma by means of opposing Co-60 wedge filter fields (author's transl)]

A method of measurement is described which allows to determine the maximum dose (tumor dose) for routine radiotherapy of the breast with opposing Co-60 wedge filter stationary fields. Furthermore it could be demonstrated that--independently of the form of the mamma--a sufficiently precise dosage can also be achieved by means of a simple calculation. For this purpose one must only know the base (= distance of the dorsal field marks on the skin) and the irradiation time for the dose to be applied into the depth dose maximum of a rectangular stationary field without filter.

[Surface dose reduction achieved by means of a lead glass filter in case of teletherapy with Co 60 radiation (author's transl)]

The surface dose of irradiated patients can be reduced by the insertion of a lead glass filter with a thickness of 4 mm at the ray emergence point of a Co 60 gammatron. The lead glass which is made stable against color alterations by radiation, will absorb the secondary electrons produced by the gamma radiation at the collimator and shutter system of the gammatron. The filter allows to reduce the surface dose in a tissue depth of 0,05 to 0,1 mm by a maximum rate of 16% according to the size of the irradiation field. Measurements were taken with a soft radiation chamber in several tissue depths within and outside the field using three different filtering methods (without any filter, 1 mm plexiglas, 4 mm lead glass). There are essential advantages for teletherapy of deep tumors by the use of a lead glass filter, so that the insertion of such a filter is recommended for all Co 60 units.

[Irradiation planning in conservative treatment of cancer of the breast (author's transl)]

Investigations of homogeneous irradiation of the breast with opposed wedge filter fields are presented. Isodose plans calculated with the help of computer programs were compared with measurements of isodose distributions (LiF rods in polystyrol phantoms), and the possibility of optimizing the irradiation method by means of computed plans was examined. Differences between the calculated and the measured values maximally amounted to 10% (programs SIDOS U2 and COMRAD). The calculations correctly describe the place of dose maxima, the homogeneity of the irradiation and tendency to isodose shift caused by variation of the shape of the breast, of the angle of incidence of radiation and of the angles of the wedges. The results are demonstrated using isodose lines in the mediolateral and in the craniocaudal plane of the breast.

[Reduction of the surface dose of Co 60 rays in a tissue depth of 0 to 3 mm by means of a magnetic field (author's transl)]

In an air gap of 10 centimeters of width lying over a U-shaped iron core, a magnetic field with an intensity of B greater than or equal to 0,069 Tesla is produced by two permanent magnetic plates. This field is arranged behind the diaphragm unit of a Co-60 gammatron at right angle to the direction of radiation, so the surface dose can be reduced until a depth of 3 millimeters. This magnetic field diffracts the secondary electrons emanating from the diaphragms of the gammatron in such a manner that they cannot contribute to the surface dose within or beyond the irradiation field. Depending on the size of the irradiation field, the magnet allows to reduce the dose by 30% at most in a tissue depth of 5 to 10 mg/cm2. Measures were taken by means of a soft radiation chamber for different tissue depths within and beyond the irradiation field.

[The dosage for tangential pendulum irradiation of the thoracic wall using 60Co in surgically treated cancer of the breast and the irradiation of the parasternal lymph nodes (author's transl)]

The determination of the dose to the patient during excentric pendulum irradiation of the thoracic wall is described. The dose delivered in the course of irradiation is simultaneously measured at the patient's surface, using a measuring system with LiF-rods which was especially developed for this purpose. The value obtained has to be multiplied with a correction factor FK=0.96 in order to yield the maximum dose, being located at a depth of 2.5 mm below the skin. The accuracy of this method for determination of doses is discussed, and the deviations are shown not to exceed 5 or 6% of the total dose. The dosage by means of tube chamber measurement is represented as an alternative method. The parasternal lymph nodes are irradiated, in addition to the dose from pendulum irradiation, with a fixed field and employing a lead wedge, both lymphatic chains thus receiving a homogeneous dose.

[Tangential pendulum irradiation of the thoracic wall with co-60 during radiation therapy of surgically treated cancers of the breast: comparison of measurement and computation methods for irradiation planning (author's transl)]

The irradiation technique for tangential pendulum 60-Co-irradiation of the thoracic wall is described, and the possibility of a homogeneous irradiation of the thoracic region of interest by means of individual irradiation planning together with a careful, but practicable, technique of positioning and adjustment is shown. The radiation load to the lung can be kept on a moderate level. Phantom measurements with thermoluminescence probes, films and an ionization chamber have been performed for three typical forms of the thorax. Dose distributions thus obtained show a satisfying accordance with calculated values of the dose, the deviations amounting to 3 to 8%. The EDP program applied, COMRAD, thus permits computation of individual pendulum isodoses with sufficient accuracy in practice, and therefore, may be used regularly.

[Comparison of measured relative isodose distributions in tangential stationary fields of Co-60 radiation with calculated isodose plans (author's transl)]

The relative isodose distributions in tangential stationary fields are measured in rectangular phantoms by means of four different methods: film measurements, thermoluminescence probes, ionization chamber, and semiconductor probes. The different measuring methods are compared, and the influence exercised by the part of the field running in the air is examined. Within the scope of their applicability, all measuring methods produce the same values which differ only by +/- 1%. It is possible to reach a better estimation of the dose distribution in the depth of the "partial fields" (a part of which is running in the air) by reducing adequately a "complete field". Furthermore, isodose distributions of measured "partial fields" are compared with calculations from a programme for the irradiation planning (programme COMRAD), and they are discussed. It is shown that the losses due to scattered radiation are not rendered by the calculation.