Contribution of Genetic Background to the Radiation Risk for Cancer and Non-Cancer Diseases in Ptch1+/- Mice.

Experimental mouse studies are important to gain a comprehensive, quantitative and mechanistic understanding of the biological factors that modify individual risk of radiation-induced health effects, including age at exposure, dose, dose rate, organ/tissue specificity and genetic factors. In this study, neonatal Ptch1+/- mice bred on CD1 and C57Bl/6 background received whole-body irradiation at postnatal day 2. This time point represents a critical phase in the development of the eye lens, cerebellum and dentate gyrus (DG), when they are also particularly susceptible to radiation effects. Irradiation was performed with γ rays (60Co) at doses of 0.5, 1 and 2 Gy, delivered at 0.3 Gy/min or 0.063 Gy/min. Wild-type and mutant mice were monitored for survival, lens opacity, medulloblastoma (MB) and neurogenesis defects. We identified an inverse genetic background-driven relationship between the radiosensitivity to induction of lens opacity and MB and that to neurogenesis deficit in Ptch1+/- mutants. In fact, high incidence of radiation-induced cataract and MB were observed in Ptch1+/-/CD1 mutants that instead showed no consequence of radiation exposure on neurogenesis. On the contrary, no induction of radiogenic cataract and MB was reported in Ptch1+/-/C57Bl/6 mice that were instead susceptible to induction of neurogenesis defects. Compared to Ptch1+/-/CD1, the cerebellum of Ptch1+/-/C57Bl/6 mice showed increased radiosensitivity to apoptosis, suggesting that differences in processing radiation-induced DNA damage may underlie the opposite strain-related radiosensitivity to cancer and non-cancer pathologies. Altogether, our results showed lack of dose-rate-related effects and marked influence of genetic background on the radiosensitivity of Ptch1+/-mice, supporting a major contribution of individual sensitivity to radiation risk in the population.

Osteotomy in the newborn classic bladder exstrophy patient: A comparative study.

INTRODUCTION: Pelvic osteotomy is indicated in classic bladder exstrophy (CBE) patients with a wide pubic diastasis or non-malleable pelvis. While the safety of pelvic osteotomy in delayed and failed closures is established, there remains less clarity on their safety in newborns. The authors herein sought to present their experience with CBE patients who underwent pelvic osteotomy for assistance with bladder closure during both the newborn and delayed time periods. OBJECTIVE: The authors hypothesize that pelvic osteotomy during exstrophy closure may be performed safely in newborns with few perioperative or post-operative negative sequelae. STUDY DESIGN: A prospectively maintained IRB-approved database was reviewed for CBE patients who underwent osteotomy during primary closure. Patient demographics, performing institution (authors' or outside), closure outcome, diastasis width, and post-operative complications were noted. Patient subgroups included newborn and delayed (>28 days of life) closures. Failure was defined as bladder dehiscence, prolapse, outlet obstruction, or vesicocutaneous fistula requiring reoperation. Orthopedic complications included nerve palsies, superficial pin-site infection, and bladder neck erosion by orthopedic hardware. Analyses were performed using a Chi-square test. RESULTS: 286 patients were included: 186 newborn and 100 delayed closures. The authors' institution performed 109 cases (44 newborn and 65 delayed). Within the overall newborn closure cohort, no significant differences were found in outcomes among the osteotomy types with success rates of 80%, 60.8%, and 71.4% in the combined, posterior iliac, and anterior innominate groups, respectively (p = 0.24). In the delayed group, success rates were significantly different with rates of 100%, 72.4%, and 93.8% in the combined, posterior iliac, and anterior innominate groups, respectively (p < 0.001). Febrile urinary tract infection (UTI) was the most common complication at 8% (23/286). Only 1.7% (5/286) of patients had orthopedic complications with 3 patients in the newborn cohort, 2 patients in the delayed cohort, and only one patient requiring reoperation. DISCUSSION: Orthopedic complications are rare in CBE patients who undergo osteotomies regardless of the closure period. No clinically significant difference in orthopedic complication rate was found between newborn and delayed closure periods. CONCLUSIONS: While current trends have moved toward delayed primary closures, there remains a role for osteotomy during exstrophy closure in select newborn patients and can be performed safely with few complications.

New Insights on the Basic Science of Bladder Exstrophy-epispadias Complex.

The exstrophy-epispadias complex is a rare congenital anomaly presenting as a wide spectrum of disorders. The complex nature of this malformation leads to continuous investigations of the basic science concepts behind it. Elucidating these concepts allows one to fully understand the mechanisms behind the disease in order to improve diagnosis, management, and treatment ultimately leading to improvement in patient quality of life. Multiple technological advancements within the last 10 years have been made allowing for new studies to be conducted. Herein, the authors conduct a literature review of studies from 2009 to 2019, considering novel theories regarding the genetics, embryology, bladder, bony pelvis, prostate, and genitalia of patients with bladder exstrophy-epispadias complex.

Bioaugmentation with PGP-trace element tolerant bacterial consortia affects Pb uptake by Helianthus annuus grown on trace element polluted military soils.

In this study, we sought to compose consortia of plant growth-promoting (PGP) and trace element tolerant bacteria, to improve plant growth and inhibit uptake and translocation of trace elements, eventually allowing the cultivation of profitmaking crops on trace elements polluted soils, reducing the risks of entrance of these elements into the food chain. Sunflower (Helianthus annuus L.) was grown on two polluted military soils (MS1 and MS2) in greenhouse microcosms and inoculated with three different bacterial consortia (C1, C2, C3). Growth and physiological status of the plants were unaffected during the experiment with the inoculation. After 2 months, plants were harvested. Consortium C2 and C3 decreased Pb shoot bioaccumulation by respectively 80-85% when plants were grown in the MS1 and even to concentrations below detection limit in plants grown in MS2. Differences in uptake and (sub)cellular localization of Pb and Cd in selected bacterial isolates were investigated in vitro by TEM-EDX. Pb absorption was observed by Bacillus wiedmanni ST29 and Bacillus paramycoides ST9 cultures. While adsorption at the bacterial cell wall was observed by Bacillus paramycoides ST9 and retention in the extracellular matrix by Cellulosimicrobium cellulans ST54.

Practice patterns in classic bladder exstrophy: A global perspective.

INTRODUCTION: While evaluation and management options for classic bladder exstrophy (CBE) patients are numerous and varied, little is known regarding the relative utilization of these different methods throughout the world. A large group of exstrophy surgeons practicing globally was surveyed, seeking to document their methods of care. METHODS: A list of international exstrophy surgeons' email addresses was compiled using professional contacts and referral networking. An online survey was sent to each email address. Surgeons who had not performed a CBE closure within the previous 5 years were excluded. Survey questions queried the respondents' surgical practice type, years since training, and their preferred methods of preoperative evaluation, operative management, and postoperative management. Survey invitations were sent out starting in December 2014 and responses were collected for approximately 6 months. RESULTS: A total of 1152 valid email addresses were invited, resulting in 293 respondents (25%) from 39 countries and every American Urological Association (AUA) section. Seventy-six were excluded, leaving 217 respondents (Table). Respondents reported a median of 17 years since finishing their surgical training (IQR 8-25 years). Practice types included pediatric urology (n = 209), general urology (n = 9), pediatric surgery (n = 59), and other practice makeup (n = 3). On subgroup analyses, there were no significant regional practice differences, with the exception of complete primary repair of exstrophy (CPRE) and oral opioid prescribing being significantly higher in North America compared to other regions. DISCUSSION: Findings indicate that there may be diversity in CBE practice patterns globally. While most responding surgeons from regions outside of North America indicated modern staged repair of exstrophy (MSRE) as their preferred closure technique, a relatively equal distribution of respondents from North America selected CPRE and MSRE. A majority of North American surgeons chose performing osteotomies for both newborn and delayed closures, while an appreciable number of respondents from other regions selected never using osteotomies in their closures. Limitations to this study include a low survey response rate, particularly from surgeons outside of the United States, which may have significantly impacted the ability to draw meaningful global comparisons. CONCLUSIONS: Global variation among practices of surgeons performing CBE closures may exist. The wide range of methods demonstrated by this survey suggests the need for more conclusive comparative studies to elucidate whether an optimal standard exists. Local social factors, access to surgical expertise and transportation to referral centers, and finances play a role in what constitutes the best operative approach.

Phytostabilization of Pb and Cd polluted soils using Helianthus petiolaris as pioneer aromatic plant species.

The area of soils polluted with heavy metals is increasing due to industrialization and globalization. Aromatic plant species can be a suitable alternative way for agricultural valorization and phytomanagement of such soils by the commercialization of essential oils avoiding risks for the food chain. The potential of growing Helianthus petiolaris in heavy metal polluted soils was assessed in pot experiments using spiked soils and soils from a shooting range. In terms of phytostabilization, H. petiolaris could grow in soils containing 1000 mg/kg Pb2+, 50 mg/kg Cd2+, accumulating more than three times the soil Cd content in the aerial parts and translocating significant amounts of Pb to the aerial parts when growing in soils polluted with up to 500 mg/kg Pb. When phytostabilization is considered, phytotoxicity of heavy metals strongly depends on the rhizospheric microbial communities, either by mitigating trace element phytotoxicity or promoting plant growth via phytohormone production. So, the effects of heavy metals on the diversity of the rhizospheric bacterial community were assessed using DNA-fingerprinting.

Cancer risk from low dose radiation in Ptch1+/- mice with inactive DNA repair systems: Therapeutic implications for medulloblastoma.

DSBs are harmful lesions produced through endogenous metabolism or by exogenous agents such as ionizing radiation, that can trigger genomic rearrangements. We have recently shown that exposure to 2 Gy of X-rays has opposite effects on the induction of Shh-dependent MB in NHEJ- and HR-deficient Ptch1+/- mice. In the current study we provide a comprehensive link on the role of HR/NHEJ at low doses (0.042 and 0.25 Gy) from the early molecular changes through DNA damage processing, up to the late consequences of their inactivation on tumorigenesis. Our data indicate a prominent role for HR in genome stability, by preventing spontaneous and radiation-induced oncogenic damage in neural precursors of the cerebellum, the cell of origin of MB. Instead, loss of DNA-PKcs function increased DSBs and apoptosis in neural precursors of the developing cerebellum, leading to killing of tumor initiating cells, and suppression of MB tumorigenesis in DNA-PKcs-/-/Ptch1+/- mice. Pathway analysis demonstrates that DNA-PKcs genetic inactivation confers a remarkable radiation hypersensitivity, as even extremely low radiation doses may deregulate many DDR genes, also triggering p53 pathway activation and cell cycle arrest. Finally, by showing that DNA-PKcs inhibition by NU7441 radiosensitizes human MB cells, our in vitro findings suggest the inclusion of MB in the list of tumors beneficiating from the combination of radiotherapy and DNA-PKcs targeting, holding promise for clinical translation.

Comparison of hematologic toxicity between 3DCRT and IMRT planning in cervical cancer patients after concurrent chemoradiotherapy: a national multi-center study.

PURPOSE: To compare the incidence and severity of acute and chronic hematologic toxicity (HT) in patients treated with three-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) for curative treatment of cervical cancer and to ascertain the dosimetric parameters of two techniques associated with acute and chronic HT. MATERIALS AND METHODS: A total of 127 patients with cervical cancer receiving concomitant pelvic radiotherapy (RT) and cisplatin were evaluated. Pelvic bone marrow (BM) was contoured for each patient and divided into five sub-regions: lumbosacrum (LS), ilium (IL), lower pelvis (LP), pelvis (P), and whole pelvis (WP). The volume of each BM region receiving 10, 20, 30, and 40 Gy was calculated (V10, -V20, -V30, and -V40). The lowest level of hemoglobin, leukocyte, neutrophil, and platelet counts were obtained during chemoradiotherapy and six months after RT. The nadir values were graded according to Common Terminology Criteria for Adverse Events (version 3.0). RESULTS: Grade 2 or greater acute anemia, leukopenia, neutropenia, thrombocytopenia was observed in 2%, 41.5%, 12% ,and 0% in 3DCRT group and in 27%, 53%, 24.5%, and 4.5% in IMRT group, respectively. Grade 2 or greater chronic anemia, leukopenia, neutropenia, and thrombocytopenia was observed in 11%, 10%, 6%, and 0% in 3DCRT group and in 11%, 9%, 4.5%, and 0% in IMRT group, respectively. LS-V30, 40; IL-V10, 20, 30, 40; LP-V10, 20 ,40; P-V10, 20, 30, 40, and TP-V10, 20, 30, 40 were significantly reduced with IMRT planning compared to 3DCRT planning. Logistic regression analysis of potential predictors showed that none of the dosimetric parameters were significant for predicting acute and chronic HT. CONCLUSION: The present findings showed that IMRT planning reduced irradiated BM volumes compared to 3DCRT planning. However, no difference between the two techniques was observed in terms of acute and chronic HT. Further studies are needed to confirm these results.

A mechanistic model for medulloblastoma induction in mice.

Medulloblastomas in Patched heterozygous mice (Ptc1(+/-) mice) are induced with high probability by ionizing radiation applied in the immediate post-natal period. A mathematical model is described here that accommodates the dependence of the medulloblastoma incidence on dose, age at exposure and age. The model assumes that the first step in the development of the cancer is already present in all cells of the patched mouse due to germ-line inactivation of one allele of the patched tumor suppressor gene. The subsequent rate-limiting step is dependent linearly on dose at least up to 3 Gy. The observed strong decrease in carcinogenic effect of radiation between exposure on day 1 and day 10 is described by a physiological elimination of target cells during post-natal maturation of the brain. A single malignant cell develops into a tumor following a gamma-distribution with mean of about 160 days. The multiplicity of medulloblastomas is predicted.

The radiation bystander effect and its potential implications for human health.

A long-held dogma in radiation biology has been that the biological effects of exposure to ionizing radiation occur as a result of damage in directly irradiated cells and that no effect would occur in neighboring unirradiated cells. This paradigm has been frequently challenged by reports of radiation effects in unirradiated or 'bystander' cells receiving signals from directly irradiated cells, an issue that may have substantial impact on radiation risk assessment and development of radiation-based therapies. Radiation-induced bystander effects have been shown in single-cell systems in vitro for an array of cancer relevant endpoints, and may trigger damage in more complex 3-D tissue systems. They may be mediated by soluble factors released by irradiated cells into the extracellular environment and/or by the passage of mediator molecules through gap-junction intercellular communication. To date, evidence that radiation-associated bystander or abscopal responses are effectual in vivo has been limited, but new data suggest that they may significantly affect tumor development in susceptible mouse models. Further understanding of how the signal/s is transmitted to unirradiated cells and tissues and how it provokes long-range and significant responses is crucial. By summarizing the existing evidence of radiation induced bystander-like effects in various systems with emphasis on in vivo findings, we will discuss the potential mechanisms involved in these observations and how effects in bystander cells contribute to uncertainties in assessing cancer risks associated with radiation exposure.

Role of connexin43 and ATP in long-range bystander radiation damage and oncogenesis in vivo.

Ionizing radiation is a genotoxic agent and human carcinogen. Recent work has questioned long-held dogmas by showing that cancer-associated genetic alterations occur in cells and tissues not directly exposed to radiation, questioning the robustness of the current system of radiation risk assessment. In vitro, diverse mechanisms involving secreted soluble factors, gap junction intercellular communication (GJIC) and oxidative metabolism are proposed to mediate these indirect effects. In vivo, the mechanisms behind long-range 'bystander' responses remain largely unknown. Here, we investigate the role of GJIC in propagating radiation stress signals in vivo, and in mediating radiation-associated bystander tumorigenesis in mouse central nervous system using a mouse model in which intercellular communication is downregulated by targeted deletion of the connexin43 (Cx43) gene. We show that GJIC is critical for transmission of oncogenic radiation damage to the non-targeted cerebellum, and that a mechanism involving adenosine triphosphate release and upregulation of Cx43, the major GJIC constituent, regulates transduction of oncogenic damage to unirradiated tissues in vivo. Our data provide a novel hypothesis for transduction of distant bystander effects and suggest that the highly branched nervous system, similar to the vascular network, has an important role.

Opposite modifying effects of HR and NHEJ deficiency on cancer risk in Ptc1 heterozygous mouse cerebellum.

Heterozygous Patched1 (Ptc1(+/-)) mice are prone to medulloblastoma (MB), and exposure of newborn mice to ionizing radiation dramatically increases the frequency and shortens the latency of MB. In Ptc1(+/-) mice, MB is characterized by loss of the normal remaining Ptc1 allele, suggesting that genome rearrangements may be key events in MB development. Recent evidence indicates that brain tumors may be linked to defects in DNA-damage repair processes, as various combinations of targeted deletions in genes controlling cell-cycle checkpoints, apoptosis and DNA repair result in MB in mice. Non-homologous end joining (NHEJ) and homologous recombination (HR) contribute to genome stability, and deficiencies in either pathway predispose to genome rearrangements. To test the role of defective HR or NHEJ in tumorigenesis, control and irradiated Ptc1(+/-) mice with two, one or no functional Rad54 or DNA-protein kinase catalytic subunit (DNA-PKcs) alleles were monitored for MB development. We also examined the effect of Rad54 or DNA-PKcs deletion on the processing of endogenous and radiation-induced double-strand breaks (DSBs) in neural precursors of the developing cerebellum, the cells of origin of MB. We found that, although HR and NHEJ collaborate in protecting cells from DNA damage and apoptosis, they have opposite roles in MB tumorigenesis. In fact, although Rad54 deficiency increased both spontaneous and radiation-induced MB development, DNA-PKcs disruption suppressed MB tumorigenesis. Together, our data provide the first evidence that Rad54-mediated HR in vivo is important for suppressing tumorigenesis by maintaining genomic stability.

Medulloblastoma: role of developmental pathways, DNA repair signaling, and other players.

Medulloblastoma is a cerebellar tumor affecting children and young adults, and accounts for approximately one fifth of all pediatric brain tumors. Despite multimodal therapy that includes surgery, radiotherapy and chemotherapy, recurrence is frequent and overall mortality rate remains relatively high. Moreover, radiation therapy results in severe effects on intellect, and younger age of treatment correlates with larger deficits. Improvements in therapy of this childhood tumor will focus increasingly on the clarification of the exact cellular origin and the genetic mechanisms contributing to tumor formation, and on new targeted therapeutic options. Aberrant activation of the Hedgehog (Hh) and Wnt developmental pathways is associated with medulloblastoma, but deregulation of other molecular pathways, including insulin-like growth factor (IGF) signaling, has also been implicated in the pathogenesis of the tumor. Recent observations in mouse models have demonstrated the importance of genome surveillance, as defects in DNA repair pathways in animals can lead to genomic instability in neural progenitor cells, resulting in medulloblastoma. The current review will focus on the most recent findings on the molecular pathology of medulloblastoma and discuss their potential contribution to treatments directed by the molecular alterations.

Modulation of basal and squamous cell carcinoma by endogenous estrogen in mouse models of skin cancer.

Patched1 heterozygous mice (Ptch1(+/-)) are useful for basal cell carcinoma (BCC) studies, being remarkably susceptible to BCC induction by ultraviolet or ionizing radiation. Analogously, skin carcinogenesis-susceptible (Car-S) mice are elective for studies of papilloma and squamous cell carcinoma (SCC) induction. We previously reported a striking effect of gender on BCC induction in Ptch1(+/-) mice, with total resistance of females; likewise, Car-S females show increased skin tumor resistance relative to males. Here, we investigated the protective role of endogenous estrogen in skin keratinocyte tumorigenesis. Control (CN) and ovariectomized Ptch1(+/-) or Car-S females were irradiated for BCC induction or topically treated with chemical carcinogens for SCC induction. Susceptibility to BCC or SCC was dramatically increased in ovariectomized Ptch1(+/-) and Car-S females and restored to levels observed in males. Remarkably, progression of initially benign papillomas to malignant SCC occurred only in ovariectomized Car-S females. We explored the mechanisms underlying tumor progression and report overexpression of estrogen receptor (ER)-alpha, downregulation of ERbeta and upregulation of cyclin D1 in papillomas from ovariectomized Car-S relative to papillomas from CN females. Thus, an imbalanced ERalpha/ERbeta expression may be associated with estrogen-mediated modulation of non-melanoma skin carcinogenesis, with a key role played by cyclin D1. Our findings underscore a highly protective role of endogenous estrogen against skin tumorigenesis by diverse agents in two independent mouse models of skin cancer.

Effects of exposure of newborn patched1 heterozygous mice to GSM, 900 MHz.

Patched1 heterozygous knockout mice (Ptc1+/-), an animal model of multiorgan tumorigenesis in which ionizing radiation dramatically accelerates tumor development, were used to study the potential tumorigenic effects of electromagnetic fields (EMFs) on neonatal mice. Two hundred Ptc1+/- mice and their wild-type siblings were enrolled in this study. Newborn mice were exposed to 900 MHz radiofrequency radiation (average SAR: 0.4 W/kg for 5 days, 0.5 h twice a day) or were sham exposed. We found that RF EMFs simulating the Global System for Mobile Communications (GSM) did not affect the survival of the mice, because no statistically significant differences in survival were found between exposed and sham-exposed animals. Also, no effects attributable to radiofrequency radiation were observed on the incidence and histology of Ptc1-associated cerebellar tumors. Moreover, the skin phenotype was analyzed to look for proliferative effects of RF EMFs on the epidermal basal layer and for acceleration of preneoplastic lesions typical of the basal cell carcinoma phenotype of this model. We found no evidence of proliferative or promotional effects in the skin from neonatal exposure to radiofrequency radiation. Furthermore, no difference in Ptc1-associated rhabdomyosarcomas was detected between sham-exposed and exposed mice. Thus, under the experimental conditions tested, there was no evidence of life shortening or tumorigenic effects of neonatal exposure to GSM RF radiation in a highly tumor-susceptible mouse model.

Thermohaline structure of an inverse estuary--The Gulf of Kachchh: measurements and model simulations.

The Gulf of Kachchh (GoK) is situated in the northeastern Arabian Sea. The presence of several industries along its coastal belt makes GoK a highly sensitive coastal ecosystem. In the present study, an attempt is made for the first time to study GoK thermohaline structure and its variability, based on field measurements and model simulations. Though GoK is considered as a well-mixed system, the study reveals that only the central Gulf is well mixed. Vertical gradients in temperature and salinity fields are noticed in the eastern Gulf, where a cold and high saline tongue is observed in the subsurface layers. Salinity indicates the characteristic feature of an inverse estuary with low values (37.20 psu) near the mouth and high values (>40.0 psu) near the head of the Gulf. The model simulated temperature and salinity fields exhibit semidiurnal oscillations similar to that of field observations. Model results show cold, high saline waters advecting from the east during ebb forming a transition zone, which oscillates with tides. A high salinity tongue is seen in the bottom layer, indicating a westward flowing bottom current. The transient zone acts as an dynamic barrier, and plays a vital role in the pollutant transport.

Trajectory of an oil spill off Goa, eastern Arabian Sea: field observations and simulations.

An oil spill occurred off Goa, west coast of India, on 23 March 2005 due to collision of two vessels. In general, fair weather with weak winds prevails along the west coast of India during March. In that case, the spill would have moved slowly and reached the coast. However, in 2005 when this event occurred, relatively stronger winds prevailed, and these winds forced the spill to move away from the coast. The spill trajectory was dominated by winds rather than currents. The MIKE21 Spill Analysis model was used to simulate the spill trajectory. The observed spill trajectory and the slick area were in agreement with the model simulations. The present study illustrates the importance of having pre-validated trajectories of spill scenarios for selecting eco-sensitive regions for preparedness and planning suitable response strategies whenever spill episodes occur.

A comparative randomized field trial on intramammary and intramuscular dry cow antibiotic treatment of subclinical Staphylococcus aureus mastitis in dairy cows.

The efficacy of two dry cow treatment (DCT) regimens for subclinical Staphylococcus aureus mastitis was evaluated in naturally infected dairy cows. At dry-off, cows were assigned to two treatment groups by randomized blocks on the basis of parity and somatic cell count (SCC). Two antibiotic DCT regimens were used, namely: (1) a single intramammary infusion containing sodium nafcillin, procaine benzylpenicillin and dihydrostreptomycin; and (2) systemic cefquinome administered intramuscularly, twice at a 24-h interval. In the intramammary (IMM) treatment group, the S. aureus intramammary infection (IMI) rate was reduced from 40% (56/140 quarters) before dry-off to 20% (28/140) after calving. Seventy per cent (39/56) of the S. aureus-positive quarters were negative after calving, and 13% (11/84) of the negative quarters were positive after calving. In the systemic treatment group, the S. aureus IMI rate increased from 39% (29/74 quarters) before dry-off to 55% (41/74) after calving. Twenty-eight per cent (8/29) of the S. aureus-positive quarters were negative after calving and 45% (20/45) of the negative quarters were positive after calving. The odds ratio of an S. aureus-positive quarter being negative after calving in the IMM group relative to the systemic therapy group was 44.6 (95% confidence interval = 2.1-909.1, P < 0.01). Parity, quarter, milk SCC and N-acetyl-beta-D-glucosaminidase were tested in the model, and were found to have no significant effect on S. aureus cure rates or new IMI rates. The IMM treatment resulted in a higher cure rate compared with that observed in previous studies. The very low cure rate after systemic cefquinome treatment was comparable to the spontaneous cure rate observed in untreated controls in previous studies. The unfavourable results of the cefquinome systemic DCT might reflect inadequate pharmacokinetic properties of the drug regarding poor udder penetration in subclinical mastitis and short antimicrobial effect compared with the IMM treatment.