Accuracy of alignment in breast irradiation: a retrospective analysis of clinical practice

The objective of the study was to determine the accuracy of patient positioning in radiotherapy for breast cancer. Portal images were obtained using a fast electronic megavoltage radiotherapy imaging system in 30 cases of breast cancer. Quantitative analysis of 530 megavolt portal images and comparison with 30 digitized simulation films were performed. Five linear measurements were taken for each simulation and verification film. Central lung distance (CLD) is the distance from the dorsomedial beam edge to the inner thoracic wall in the central plane of the beam. Cranial lung distance (CrLD) is the distance from the dorsomedial beam edge to the inner thoracic wall in the plane of the beam at 4 cm from the central plane. Central beam edge to skin distance (CBESD) is the distance from the skin to the ventrolateral beam edge in the central plane of the beam. The central irradiated width (CIW) is defined as the distance from the dorsomedial beam edge to the skin. The craniocaudal distance (CCD) is defined as the distance from a particular landmark to the caudal field border. Concerning patient position in the field, mean standard deviations of the difference between simulation and treatment images were 3.9 mm for the CLD, 3.2 mm at +4 cm, 3.6 mm for the CIW, 3.3 mm for the CBESD, 3.8 mm for the CCD. In 90% of all set-up for treatment, errors were less than 1 cm. The variation of the CLD was the largest set-up error. This parameter is clinically the most significant. Future treatment delivery should be improved by introducing patient positioning devices such as thermoplastic shells. The electronic portal imaging device (EPID) appears to be an adequate tool to study the accuracy of treatment set-ups like this.

In vivo biotinylated recombinant antibodies: high efficiency of labelling and application to the cloning of active anti-human IgG1 Fab fragments

In vivo biotinylation of antibody fragments with a gene fusion approach is a realistic alternative to conventional in vitro chemical labelling. We have previously reported the construction of a vector system suitable for the bacterial expression of the binding fragment of antibody (Fab) genetically linked to the C-terminal domain of Escherichia Coli biotin carboxy carrier protein (BCCP*). A minor fraction of the expressed hybrids was biotinylated in vivo and therefore able to interact with streptavidin. We now show that the large majority of bacterially-expressed Fab-BCCP* fusions are labelled with biotin when plasmid-encoded biotin holoenzyme synthetase (BirA) is co-expressed. The yield of biotinylated Fab is maximal when overexpression of BirA is driven by a second compatible plasmid. We took advantage of this property to develop a novel filter assay for the rapid identification of recombinant Fab reacting with immunoglobulin. Starting with total RNA of two newly established murine hybridoma cell lines producing anti-human IgG1 antibodies, we selected in a single experiment the bacterial clones that expressed in vivo biotinylated anti-IgG1 Fab. Sequence analysis of the isolated Fabs showed that they did not derive from a single B clone. In addition, we found that these recombinant Fabs labelled with biotin in vivo are useful for the specific detection of human IgG1 by a solid-phase immunoassay.

Mgm101p is a novel component of the mitochondrial nucleoid that binds DNA and is required for the repair of oxidatively damaged mitochondrial DNA

Maintenance of mitochondrial DNA (mtDNA) during cell division is required for progeny to be respiratory competent. Maintenance involves the replication, repair, assembly, segregation, and partitioning of the mitochondrial nucleoid. MGM101 has been identified as a gene essential for mtDNA maintenance in S. cerevisiae, but its role is unknown. Using liquid chromatography coupled with tandem mass spectrometry, we identified Mgm101p as a component of highly enriched nucleoids, suggesting that it plays a nucleoid-specific role in maintenance. Subcellular fractionation, indirect immunofluorescence and GFP tagging show that Mgm101p is exclusively associated with the mitochondrial nucleoid structure in cells. Furthermore, DNA affinity chromatography of nucleoid extracts indicates that Mgm101p binds to DNA, suggesting that its nucleoid localization is in part due to this activity. Phenotypic analysis of cells containing a temperature sensitive mgm101 allele suggests that Mgm101p is not involved in mtDNA packaging, segregation, partitioning or required for ongoing mtDNA replication. We examined Mgm101p's role in mtDNA repair. As compared with wild-type cells, mgm101 cells were more sensitive to mtDNA damage induced by UV irradiation and were hypersensitive to mtDNA damage induced by gamma rays and H2O2 treatment. Thus, we propose that Mgm101p performs an essential function in the repair of oxidatively damaged mtDNA that is required for the maintenance of the mitochondrial genome.

Targetting of the N-terminal domain of the human papillomavirus type 16 E6 oncoprotein with monomeric ScFvs blocks the E6-mediated degradation of cellular p53

The E6 protein of cancer-associated human papillomavirus type 16 (HPV16) binds to cellular p53 and promotes its degradation through the ubiquitin pathway. In an attempt to identify the regions of E6 that could be targetted for functional inhibition, we generated monoclonal antibodies to the HPV16 E6 oncoprotein (16E6) and analysed their effect on E6-mediated p53 in vitro degradation. The isolated antibodies recognize the 16E6 oncoprotein expressed in the CaSki carcinoma cell line and strongly inhibit the proteolysis of p53 in vitro by binding specifically to a region of 10 residues located at the N-terminal end of 16E6. The variable regions of these antibodies were cloned and expressed in E. coli as single chain Fvs (scFvs). Purified scFvs were present in monomeric form and totally abolished 16E6-mediated p53 degradation by preventing the formation of E6/p53 protein complexes. Our results demonstrate that monovalent binding of scFvs to the N-terminal end of 16E6 abrogates the biological mechanisms leading to the degradation of p53, and they suggest that this region of 16E6 may be a useful in vivo target for blocking the oncogenic activity of HPV16 E6 protein.

[Changes in the plasma concentration of vitamin A, vitamin E and beta-carotene in polytrauma patients and in patients with osteitis in relation to course of illness]

In 17 patients with osteitis and 16 polytraumatized patients changes in the plasma levels of vitamin A, vitamin E and beta-carotene were investigated. Plasma samples taken preoperatively, daily during the first three days and then twice a week postoperatively were analysed for fat-soluble vitamins by high performance liquid chromatography (HPLC). Significant changes in plasma levels of all three components depending on the outcome of injury were found in all patients. Increased levels were observed in patients that survived the injury, while in those who died a significant decrease was observed. Recommendations regarding the supplementation with these vitamins in clinical practice can not be made based on these results, but substitute might prove beneficial for vitamin E in certain types of injury.

[In vitro study of a paclitaxel-radiotherapy combination on a human epidermoid tumor cell line]

PURPOSE

Paclitaxel is an agent which stabilizes microtubules, and has been shown to block different cells in the G2/M phase of the cell cycle and thus to modulate their radioresponsiveness. We investigated the radiosensitizing potential of paclitaxel in human head and neck cancer cells.

MATERIALS AND METHODS

ZMK-1 cells were incubated with paclitaxel for 3, 9, or 24 h before or during 24 h after irradiation. Paclitaxel concentrations of 70 nM, 7 nM, and 0.7 nM were chosen to obtain equivalent toxicity at the different incubation times: 3 h, 9 h, and 24 h, respectively. Radiation doses ranged from 0 to 8 Gy using 60Co source. Cell survival was measured by a standard clonogenic assay after a 9-day incubation. Flow cytometry was used to measure the capacity of paclitaxel to accumulate cells in the G2/M phase.

RESULTS

Paclitaxel alone possessed cytotoxicity dependent on time and concentration. There was a total of 40% of cells accumulated in G2/M after 24-36 h. When combined with radiation, the 9 h preincubation resulted in a radiosensitization. The 3 h pre-incubation as well as the 24 h post-incubation resulted in an infra-additive effect.

CONCLUSION

In our cells a radiosensitizing effect of paclitaxel could not be demonstrated unambiguously. The blockage of the cells in the G2/M phase is not the only mechanism to explain the potential radiosensitization of paclitaxel.

Detection of soluble HLA-G molecules in plasma and amniotic fluid

Although the cDNA sequence of HLA-G antigens is compatible with their expression as soluble molecules (sHLA-G), the determination of native sHLA-G levels in body fluids has not yet been described. The lack of this information is likely to reflect the difficulties in developing an assay suitable to measure sHLA-G antigens in the presence of soluble HLA-A, -B and -C (sHLA-I) antigens, since most of the available anti-HLA-G mAb do not detect soluble beta2-m associated HLA-G antigens or crossreact with sHLA-I antigens. Therefore, we have developed a two-step assay which eliminates the interference of classical HLA class I antigens. In the first step, the sample is depleted of sHLA-I antigens and of HLA-E antigens with mAb TP25.99. Then, HLA-G antigens are captured with mAb W6/32 and detected with anti-beta2-m mAb in ELISA. Utilizing this assay, sHLA-G antigen levels were measured in EDTA plasma from 92 controls with known HLA types, 28 women at delivery and the corresponding cord bloods and in 50 amniotic fluids. Mean sHLA-G plasma levels did not differ between males (24.9+/-3.0 SEM ng/ml; n=42) and females (20.1+/-2.1 SEM ng/ml; n = 50). However, sHLA-G levels in HLA-A11 positive probands (mean: 13.0+/-4.4 SEM ng/ml; n=12) were significantly (P<0.05) lower than in HLA-A11 negative ones (mean: 24.5+/-2.0 SEM ng/ml; n=80). sHLA-G levels in women at delivery (mean: 22.9+/-2.2 SEM ng/ml; n=28) were in the range of controls but were significantly (P<0.001) reduced in the corresponding cord bloods (mean: 13.8+/-1.5 SEM ng/ml; n=28). sHLA-G levels in amniotic fluids (mean: 15.5 + 1.0 SEM ng/ml; n=50) were significantly (P<0.001) lower than in plasma. sHLA-G levels were 5 and 11% of those of sHLA-I antigens in plasmas and amniotic fluids, respectively. Individual sHLA-G levels were not correlated with sHLA-I levels. SDS-PAGE analysis of plasma sHLA-G antigens revealed two molecular variants with a 35 kD and a 27 kD MW corresponding to the sizes of sHLA-G1 and -G2 isoforms. In conclusion, our study has shown that the two-step assay we have developed is reliable in measuring sHLA-G antigen levels. This assay will facilitate the analysis of the biological and clinical significance of sHLA-G antigens in plasma.

Human complement factor H deficiency associated with hemolytic uremic syndrome

This study reports on six cases of deficiency in the human complement regulatory protein Factor H (FH) in the context of an acute renal disease. Five of the cases were observed in children presenting with idiopathic hemolytic uremic syndrome (HUS). Two of the children exhibited a homozygous deficiency characterized by the absence of the 150-kD form of Factor H and the presence, upon immunoblotting, of the 42-kD Factor H-like protein 1 (FHL-1) and other FH-related protein (FHR) bands. Southern blot and PCR analysis of DNA of one patient with homozygous deficiency ruled out the presence of a large deletion of the FH gene as the underlying defect for the deficiency. The other four children presented with heterozygous deficiency and exhibited a normal immunoblotting pattern of proteins of the FH family. Factor H deficiency is the only complement deficiency associated with HUS. These observations suggest a role for FH and/or FH receptors in the pathogenesis of idiopathic HUS.

Management of extremely low birth weight infants: perceptions of viability and parental counseling practices

OBJECTIVE

To determine physician opinions, parental counseling, and medical practices for extremely low birth weight (LBW) infants.

METHODS

A retrospective survey was sent in August 1996 to 450 California physicians practicing obstetrics.

RESULTS

There was a 41% response rate. The mean thresholds for antenatal steroid administration, cesarean delivery for fetal distress and delivery room resuscitation were gestational age between 23 and 24 weeks and weight close to 500 g. Most obstetricians counsel parents regarding survival, resuscitation, and possible death in the delivery room before delivery of an extremely LBW infant. Just over 60% of obstetricians believe that parents have a role in deciding not to resuscitate an infant born at 22 weeks' gestation, this decreases to less than 50% at 24 weeks, and decreases further to less than 30% by 26 weeks' gestation. Just over 40% of obstetricians report their counseling is affected by pediatric opinion, 33% by previous maternal perinatal losses, and less than 20% by maternal drug use or lack of prenatal care, and young maternal age. Language barriers, parental education level, and family insurance affect treatment options in less than 10% of obstetricians.

CONCLUSION

Obstetric opinions about delivery room resuscitation of extremely LBW infants are influenced by birth weight and gestational age thresholds, infant, and parental factors. There is a limited willingness by physicians to allow a parental role in decision making in the delivery room for extremely LBW infants.

Adjuvant vaginal high-dose-rate afterloading alone in endometrial carcinoma: patterns of relapse and side effects following low-dose therapy

OBJECTIVE

This retrospective study was conducted to document the incidence and location of recurrences as well as the rate of side effects following low-dose postoperative high-dose-rate (HDR) brachytherapy in patients with endometrial carcinoma.

METHODS

From 1987 to 1993, 122 patients with moderate-risk (78) and high-risk (44) endometrial carcinoma underwent adjuvant vaginal irradiation. All patients received three fractions of 7 Gy specified on the surface of the vaginal cylinder.

RESULTS

Relapses occurred in 12 (9. 8%) patients on average after 25.6 months. Seven (5.7%) patients had a sole pelvic recurrence; in 2 (1.6%) of those the relapse was located in the vagina only. Three (2.5%) patients had a pelvic relapse combined with distant metastases. Distant metastases alone were diagnosed in 2 (1.6%) patients. A tumor recurrence was diagnosed in 3 of 78 (3.8%) patients with moderate-risk disease and in 9 of 44 (20.5%) patients with high-risk disease. The estimated 5-year relapse-free survival was 94% for patients with moderate-risk and 74% for patients with high-risk tumors (P = 0.004). Neither severe nor chronic complications were noted.

CONCLUSION

Even low doses of HDR brachytherapy seem sufficient for excellent vaginal disease control in moderate-risk disease. In advanced tumors combined radiation therapy is warranted for improved pelvic disease control.

Treatment of primary malignant rhabdoid tumor of the brain: report of three cases and review of the literature

PURPOSE

Primary malignant rhabdoid tumor (MRT) of the central nervous system is an extremely aggressive tumor predominantly related to early childhood, with characteristic histopathological findings but unclear histogenesis. Owing to its low incidence, little knowledge exists concerning the best therapeutic strategy.

METHODS AND MATERIALS

Three children of our hospital with MRT of the brain underwent a maximum tumor resection followed by multidrug chemotherapy and radiation therapy to the craniospinal axis.

RESULTS

Relapse was disseminated along the spinal subarachnoid spaces in one child and occurred at the primary tumor site in the other two patients. Maximum survival was 15 months from diagnosis.

CONCLUSION

A review of patients reported in the literature and a comparison to our patients reveals a high propensity to early local relapse and meningeal dissemination. In the absence of more effective therapeutic options, we recommend multidisciplinary treatment of patients in good general condition and with resectable disease. In particular, following radiation therapy, tumor remissions and delay of tumor regrowth have been observed.

[Significance and possibilities of histopathologic diagnosis in breed-specific skin diseases]

An increasing number of punch biopsies is submitted for histopathology. Results are often disappointing for the veterinary pathologist as well as the referring veterinarian. Inappropriate timing of sampling, selection and preparation of the biopsy site, type of biopsy, biopsy technique and fixation as well as incomplete histories often contribute to insufficient diagnosis and interpretation of skin lesions. The introduction of this review gives an overview of the requirements for a satisfying evaluation of skin lesions and the limits of diagnostic histopathology on skin samples, especially punch biopsies. The second part summarizes more frequent dermatohistopathological diagnoses according to the pattern analysis of skin lesions, using examples of skin diseases with breed predisposition. Among the described skin lesions are the dermatoses associated with endocrine dysfunction, cutaneous mucinosis, Vogt-Koyanagi-Harada-like syndrome, alopecia of color mutants, dermatomyositis, granulomatous sebadentitis, Malassezia dermatitis, pyoderma and atopic dermatitis.

Expression of major histocompatibility complex class II antigen in neoplastic cells of canine cutaneous histiocytoma

Forty five cases of canine cutaneous histiocytoma (CCH) were examined by immunohistology for expression and distribution of major histocompatibility complex (MHC) class II antigen in neoplastic cells. In addition, expression of lysozyme and calprotectin (leucocyte protein L1) in neoplastic cells was investigated. Furthermore, B and T lymphocytes were demonstrated by antibodies against the CD3 antigen, IgG, and IgM. Neoplastic cells showed two staining patterns for MHC class II antigen: focal juxtanuclear cytoplasmic staining and/or rim-like staining along the cell periphery. In 24 cases, a predominant or exclusive focal juxtanuclear cytoplasmic MHC class II antigen reaction in neoplastic cells, and the presence of few diffusely distributed infiltrating CD3 antigen-positive T lymphocytes were observed. Tumors with numerous neoplastic cells exhibiting staining for MHC class II antigen along the cell periphery (n = 21) showed increased inflammatory alterations, represented by disseminated and nodular infiltrations of mainly CD3 antigen-positive T cells. B cells, plasma cells, exudate macrophages, and neutrophils were rarely seen disseminated between neoplastic cells whereas their number increased within focal inflammatory infiltrates. The focal cytoplasmic reaction for MHC class II antigen in neoplastic cells might represent newly synthesized MHC class II molecules stored in vesicles, whereas staining of the cell periphery might occur due to accumulation of MHC class II molecules along the plasma membrane. The increasing expression of MHC class II molecules on the cell surface might be the decisive factor for onset and progression of tumor regression. However, the exact mechanism of priming and activation of T cells by neoplastic cells and the nature of the presented antigen are not yet known.

Expression in Escherichia coli of Y5 mutant and N-terminal domain-deleted DNA gyrase B proteins affects strongly plasmid maintenance

Escherichia coli DNA gyrase B subunit (GyrB) is composed of a 43-kDa N-terminal domain containing an ATP-binding site and a 47-kDa C-terminal domain involved in the interaction with the gyrase A subunit (GyrA). Site-directed mutagenesis was used to substitute, in both the entire GyrB subunit and its 43-kDa N-terminal fragment, the amino acid Y5 by either a serine (Y5S) or a phenylalanine residue (Y5F). Under standard conditions, cells bearing Y5S or Y5F mutant GyrB expression plasmids produced significantly less recombinant proteins than cells transformed with the wild-type plasmid. This dramatic decrease in expression of mutant GyrB proteins was not observed when the corresponding N-terminal 43 kDa mutant plasmids were used. Examination of the plasmid content of the transformed cells after induction showed that the Y5F and Y5S GyrB protein level was correlated with the plasmid copy number. By repressing tightly the promoter activity encoded by these expression vectors during cell growth, it was possible to restore the normal level of the mutant GyrB encoding plasmids in the transformed bacteria. Treatment with chloramphenicol before protein induction enabled large overexpression of the GyrB mutant Y5F and Y5S proteins. In addition, the decrease in plasmid copy number was also observed when the 47-kDa C-terminal fragment of the GyrB subunit was expressed in bacteria grown under standard culture conditions. Analysis of DNA supercoiling and relaxation activities in the presence of GyrA demonstrated that purified Y5-mutant GyrB proteins were deficient for ATP-dependent gyrase activities. Taken together, these results show that Y5F and Y5S mutant GyrB proteins, but not the corresponding 43-kDa N-terminal fragments, compete in vivo with the bacterial endogenous GyrB subunit of DNA gyrase, thereby reducing the plasmid copy number in the transformed bacteria by probably acting on the level of negative DNA supercoiling in vivo. This competition could be mediated by the presence of the intact 47-kDa C-terminal domain in the Y5F and Y5S mutant GyrB subunits. This study demonstrates also that the amino acid Y5 is a crucial residue for the expression of the gyrase B activity in vivo. Thus, our in vivo approach may also be useful for detecting other important amino acids for DNA gyrase activity, as mutations affecting the ATPase activity or GyrB/GyrB, or GyrB/GyrA protein interactions.

Expression in Escherichia coli of Y5-mutant and N-terminal domain-deleted DNA gyrase B proteins affects strongly plasmid maintenance

Escherichia coli DNA gyrase B subunit (GyrB) is composed of a 43-kDa N-terminal domain containing an ATP-binding site and a 47-kDa C-terminal domain involved in the interaction with the gyrase A subunit (GyrA). Site-directed mutagenesis was used to substitute, in both the entire GyrB subunit and its 43-kDa N-terminal fragment, the amino acid Y5 by either a serine (Y5S) or a phenylalanine residue (Y5F). Under standard conditions, cells bearing Y5S or Y5F mutant GyrB expression plasmids produced significantly less recombinant proteins than cells transformed with the wild-type plasmid. This dramatic decrease in expression of mutant GyrB proteins was not observed when the corresponding N-terminal 43-kDa mutant plasmids were used. Examination of the plasmid content of the transformed cells after induction showed that the Y5F and Y5S GyrB protein level was correlated with the plasmid copy number. By repressing tightly the promoter activity encoded by these expression vectors during cell growth, it was possible to restore the normal level of the mutant GyrB encoding plasmids in the transformed bacteria. Treatment with chloramphenicol before protein induction enabled large overexpression of the GyrB mutant Y5F and Y5S proteins. In addition, the decrease in plasmid copy number was also observed when the 47-kDa C-terminal fragment of the GyrB subunit was expressed in bacteria grown under standard culture conditions. Analysis of DNA supercoiling and relaxation activities in the presence of GyrA demonstrated that purified Y5-mutant GyrB proteins were deficient for ATP-dependent gyrase activities. Taken together, these results show that Y5F and Y5S mutant GyrB proteins, but not the corresponding 43-kDa N-terminal fragments, compete in vivo with the bacterial endogenous GyrB subunit of DNA gyrase, thereby reducing the plasmid copy number in the transformed bacteria by probably acting on the level of negative DNA supercoiling in vivo. This competition could be mediated by the presence of the intact 47-kDa C-terminal domain in the Y5F and Y5S mutant GyrB subunits. This study demonstrates also that the amino acid Y5 is a crucial residue for the expression of the gyrase B activity in vivo. Thus, our in vivo approach may also be useful for detecting other important amino acids for DNA gyrase activity, as mutations affecting the ATPase activity or the GyrB/GyrB or GyrB/GyrA protein interactions.

Un-cross-linked fibrin substrates inhibit keratinocyte spreading and replication: correction with fibronectin and factor XIII cross-linking

Wound repair is characterized by the presence of a fibrin-rich matrix, but the effect of fibrin on re-epithelialization remains unclear. In this study, we determined the effects of different fibrin matrices on cultured human neonatal keratinocytes. Using purified fibrinogen and fibrin gels generated by the enzymatic action of thrombin, batroxobin (it leads to retention of fibrinopeptide B), or Agkistrodon contortrix thrombin-like enzyme (ACTE; it leads to retention of fibrinopeptide A), we determined the effect of each of these matrices on keratinocyte morphology, attachment, spreading, and replication as compared to tissue culture plastic. Morphologically, keratinocytes seeded on fibrin surfaces were more rounded and formed three-dimensional structures. Specific cell attachment, as measured at either 37 degrees C or 4 degrees C, was not altered on the different fibrin substrates (P > .05) but was increased on fibrinogen and factor XIII cross-linked fibrin (P < .01). However, keratinocytes seeded on fibrin, regardless of the presence or absence of fibrinopeptides A or B, showed a marked decrease (up to 71%) in cell numbers by days 5 (P = .0357) and 10 (P = .0114). Keratinocyte spreading was decreased by 78.8% (P = .0006), 80.3% (P = .0001), and 89.2% (P = .0001) on thrombin-, batroxobin-, and ACTE-generated fibrin, respectively, but not on fibrinogen-coated dishes. However, either the addition of fibronectin or cross-linking of fibrin with factor XIII allowed full keratinocyte spreading to occur (P = .0002 and P = .0013, respectively). We conclude that fibrin inhibits keratinocyte spreading in the absence of other matrix or plasma proteins or cross-linking by factor XIII.

Suppression of apoptosis in COLO 205 cells by the phorbol ester TPA may be mediated by the PKC isoenzyme alpha

Apoptosis induced by an antibody to CD95/APO-1/FAS in the colon carcinoma cells COLO 205 and HT-29 is suppressed by the phorbol ester TPA. Inhibition is much more effective in COLO 205 than in HT-29 cells. The TPA effect is abrogated by the protein kinase C (PKC)-specific inhibitor Go6983 indicating a role of PKC in this process. Bryostatin 1, unlike TPA, is unable to suppress apoptosis, but inhibits the TPA-induced suppression of apoptosis. TPA also inhibits indomethacin-induced apoptosis in COLO 205 cells. COLO 205 and HT-29 cells contain the PKC isoenzymes alpha, beta(II) delta, epsilon, eta, mu and zeta. Expression and activity of PKC alpha are at least 5 times higher in COLO 205 than in HT-29 cells. This correlates with the fact that inhibition of CD95-mediated apoptosis by TPA is more prominent in COLO 205 than in HT-29 cells. Thus, these findings suggest that PKC alpha has an important role in the TPA-induced inhibition of apoptosis.

Characterization of the proliferation state in canine mammary tumors by the standardized AgNOR method with postfixation and immunohistologic detection of Ki-67 and PCNA

Paraffin-embedded tissue sections of 96 surgically removed mammary tumors from female dogs were analyzed for their proliferation state using three different methods. The AgNOR method, originally developed by Ploton and coworkers in 1986, modified and standardized by the AgNOR committee, is an easy, inexpensive silver-staining procedure used to determine cell proliferation and prognosis of various tumors. Due to the standardized staining protocol of the AgNOR method and a postfixation step, results obtained were of excellent quality for image-analysis processing. The growth fraction was evaluated by counting of immunohistologically positive-stained cells for Ki-67 or proliferating-cell nuclear antigen (PCNA). The values determined were, in general, lower with Ki-67 (MIB1) than with PCNA (PC10). Nevertheless, the labeling indices of these antigens correlated significantly (P < 0.001). Though the differences of the means between the tumor groups according to the classification system of the World Health Organization were significant for all three investigated methods (P < 0.001), there was a considerable overlap between the tumor groups concerning all investigated parameters. An exploratory data analysis (multivariate analysis) as performed to evaluate the prognostic relevance of the three methods including further anamnestic, clinical, gross, and histopathologic variables. Besides the histopathologic diagnosis (survival P < 0.001; survival time P < 0.05; reappearance of tumor growth P < 0.05), only the PCNA-labeling index (time until reappearance of tumor growth P < 0.001) was of prognostic significance.