Overall and meal-specific macronutrient intake in Belgian primary school children

The present study, first of its kind, was conducted with the objectives to understand hitherto little known aspects of candidal mastitis, like its sequential pathology, pathogenesis and clinico-biochemical changes. For this purpose, unilateral intramammary inoculation of 10 goats with Candida albicans (1.2 x 10(7) yeast cells) resulted in the development of mastitis, with gross and microscopic lesions being restricted to the infected udder halves only and without dissemination of infection to the opposite uninfected udder halves as well as other organs of the body. The experiment was continued for 40 days and after infection, there was sharp fall in milk yield and Candida albicans was directly demonstrated in the milk and re-isolated from the milk and udder tissues up to 30th day after inoculation. An increase in total immunoglobulins in the milk and plasma along with increase in total plasma proteins were also observed. Haematology revealed leukocytosis and neutrophilia. Microscopically, there was acute purulent mastitis, which later became chronic, nonpurulent and interstitial with formation of granulomas. It was concluded that Candida albicans was highly pathogenic to the lactating goat mammary gland even without immunosuppression or antibiotic treatment, resulting in severe irreversible tissue damage and nearly complete agalactia.     

Pathology of Serratia marcescens mastitis in cattle

Microbiological, cytological, histopathological, and immunohistochemical investigations were carried out on four dairy cows affected by Serratia marcescens mastitis. The animals under study were from a herd of 120 lactating cows bred in the province of Rome. In the above herd, S. marcescens mastitis showed a prevalence of 20.8%. S. marcescens was the only bacterial agent isolated, prior to and after slaughter, from the teat milk, the mammary gland and the supramammary lymph nodes of the four cows under study. Cytologically, the four subjects exhibited high cell counts in their milk, with an average of up to 5,570,000 cells/ml in S.marcescens-infected quarters. Macroscopically, nodular lesions were apparent scattered throughout the mammary parenchyma, with enlargement of the regional lymph nodes. Histologically, a chronic, non-purulent mastitis, characterized by a marked fibrous tissue proliferation and the coexistence of corpora amylacea within the glandular alveoli, was observed in association with chronic hyperplastic lymphadenitis involving the supramammary lymph nodes of the four cows. Immunohistochemically, S. marcescens was demonstrated, by means of monoclonal antibodies, both in the mammary gland and in the supramammary lymph nodes from these four animals.     

Competitive behaviour in an island population of house mice, Mus domesticus

The effects of mastitis during the late nonlactating period on colostral volume and concentrations and total yields of immunoglobulin (Ig) G1, fat, and protein in colostrum were investigated using matched pairs of mammary glands from multiparous Holstein cows. Samples of mammary secretions were collected at approximately 14 and 7 d prepartum and within 3 h after calving. At each sampling time, the glands and secretions were examined for gross abnormalities, and the California Mastitis Test was performed. Duplicate secretion samples from each gland were cultured, and somatic cell count, pH, and fat and protein concentrations were determined. The volume of colostrum obtained at the first milking of each gland was quantified using a quarter milking device, and its IgG1 concentration was measured. Colostral volume from persistently infected mammary glands was lower than that from matched uninfected glands, as was the total mass of IgG1. However, infection did not alter IgG1 concentration in colostrum. Fat and protein percentages were lower in prepartum secretions but not in colostrum from infected glands. Persistent infection was associated with increased somatic cell count and pH of secretions at all sampling times, and California Mastitis Test scores were higher for colostrum from infected glands. The appearance of secretions was extremely variable, but the presence of flakes or clots in colostrum was associated with infection. We concluded that mastitis during the late nonlactating period alters mammary gland function but is unlikely to be an important contributor to the high rate of failure of passive transfer of immunoglobulins in calves.     

Conversion of chronic staphylococcal mastitis to acute gangrenous mastitis after neutropenia in blood and bone marrow produced by an equine anti-bovine leukocyte serum

A stock strain of Staphylococcus aureus of mastitis origin, characterized by alpha-, beta-, and delta-toxins, was used to produce chronic mastitis of 20 to 300 days' duration in 6 lactating mammary quarters of 4 cows. Early acute Streptococcus agalactiae mastitis was produced in 1 additional mammary quarter of 1 cow. Equine anti-bovine leukocyte serum (EABLS) was administered to all cows by continuous intravascular drip for 12 to 32 hours. Neutropenia in blood and partial depletion of neutrophil reserve in bone marrow were produced. Chronic subclinical staphylococcal mastitis in 2 quarters of 1 cow changed to gangrenous mastitis by the 40th hour after EABLS administration and led to death of the cow. The disappearance of neutrophil leukocytes from the milk was followed by uninhibited multiplication of S aureus. Probably, staphylococcal leukocidins accelerated the destruction of neutrophils in the milk as S aureus multiplication became intensified. In another quarter of the same cow that was infected with Str agalactiae, neutrophil leukocytes were present in milk as long as 3 days after their disappearance from blood and bone marrow. This may give some indication of the extravascular life-span of the neutrophil in the udder in mastitis. The 2nd cow died at the 16th hour from the start of EABLS administration and at a time when gangrenous mastitis was in the initial stages of development. The S aureus-infected quarters of the 2 remaining cows did not become gangrenous. Administration of EABLS to these 2 cows did not significantly reduce the numbers of neutrophil leukocytes entering the milk of the 3 S aureus-infected quarters. It is concluded that continuous diapedesis of neutrophil leukocytes into the milk in chronic staphylococcal mastitis protects the gland against the development of gangrenous mastitis in the presence of a strain of S aureus capable of alpha-toxin production.     

Lymphocyte subpopulations in the mammary gland of the goat

Mammary glands of pregnant, lactating and resting goats were studied by immunohistochemistry for lymphocyte subpopulations using a panel of monoclonal antibodies. All T lymphocyte subpopulations that may have a role in the immune response, CD2+, CD4+, CD8+ and gamma delta T cells and subsets, were present in the mammary gland and were noted to increase in number progressively during pregnancy, decrease significantly during lactation, and then moderately increase during the resting period. CD4+ cells, the predominant cell type in the mammary gland, were located mainly in the connective tissue, whereas CD2+, CD8+ and TcR1-N24+ cells were predominant in the intraepithelial areas. TcR1-N6+ cells were detected almost exclusively during pregnancy, being localized mainly in the connective tissue. Their proportion decreased markedly following parturition. Very few WC1-N3+ and -N4+ cells were detected in the mammary gland. It is suggested that the majority of gamma delta T lymphocytes in the mammary gland of the goat are CD2+ CD8+ WCl-, a distinctive subset from that of the WCl+ subset in peripheral blood.     

Application of a U-13C-labeled amino acid tracer in lactating dairy goats for simultaneous measurements of the flux of amino acids in plasma and the partition of amino acids to the mammary gland

A preliminary study was conducted using lactating British Saanen goats (n = 5) at 109 to 213 d in milk that yielded 1.67 to 3.68 kg of milk/d to examine the application of a U-13C-labeled amino acid (AA) mixture obtained from hydrolyzed algal proteins as a tracer for measuring plasma flux (n = 5) and partition to the mammary gland (n = 3; arteriovenous difference) of 13 AA simultaneously. Except for Ile and Ser, there was incomplete (6 to 54%) equilibration of the tracer with AA from packed blood cells (> 90% erythrocytes) during the 6-h infusions. This result agreed with the large ratio of packed cells to gradients for plasma AA concentration that was also observed. However, net mass and isotope removals by the mammary gland were predominantly from plasma, indicating that the erythrocytes did not participate in kinetic exchanges. Plasma AA fluxes (millimoles per kilogram of metabolizable protein intake per kilogram of body weight 0.75) differed among goats that consumed different protein sources; however, overall rates were lowest for Met (5 to 14) and His (8 to 17) and highest for Leu (48 to 70) and Ala (53 to 88). On average, 25% of plasma flux was partitioned to the mammary gland. Less than 20% of His, Ser, Phe, and Ala were directed to the mammary gland; 20 to 30% of Arg, Thr, Tyr, and Leu were directed to the mammary gland; and 30 to 40% of Pro, Ile, Lys, and Val were directed to the mammary gland. The unidirectional AA flux in the mammary gland (AA apparently available for protein syntheses, oxidation, and metabolite formation) did not match the pattern that is required for casein synthesis, suggesting differences in the metabolic requirements of AA for nonmilk protein synthesis.     

Virus quantification and identification of cellular targets in the lungs and lymphoid tissues of pigs at different time intervals after inoculation with porcine reproductive and respiratory syndrome virus (PRRSV)

Sixteen 6 week old conventional pigs were inoculated by aerosol with a European strain of porcine reproductive and respiratory syndrome virus (PRRSV). Virus replication was followed by virus titration and immunofluorescence in the lungs and in associated and distant lymphoid tissues at 3, 14, 21, 35, 42 and 82 days post-inoculation (DPI). PRRSV replication was detected in alveolar macrophages, lungs, tonsils, spleen, retropharyngeal lymph nodes, bronchial lymph nodes and thoracic aortic lymph nodes at 3 DPI. The same tissues, except retropharyngeal and thoracic aortic lymph nodes, were PRRSV positive at 14 DPI. Lungs and alveolar macrophages were PRRSV positive until 35 DPI. PRRSV was not detected in heart, peripheral blood mononuclear cells and bone marrow cells. Viremia was detected from 3 to 28 DPI. Not more than 2% of alveolar macrophages were PRRSV positive even during the acute stage of infection. 80 to 94% of the PRRSV infected cells in the lungs and in lung lavaged cells were identified as macrophages using a porcine macrophage specific monoclonal antibodies. In the lymph nodes and spleen, 100% of the infected cells were macrophages. Anti-PRRSV antibodies were detected by a blocking ELISA as early as 7 DPI. the antibody titre gradually increased to reach a geometric mean titre (GMT) of 160 at 35 DPI. It remained at that level until the end of the study. These findings clearly demonstrate that PRRSV has a tropism for macrophages. PRRSV mainly replicates in macrophages of the lymphoid tissues and lungs in the acute phase of infection and persists in the lung macrophages.     

B and T cells are required for mouse mammary tumor virus spread within the mammary gland

Mouse mammary tumor virus (MMTV) is an infectious retrovirus transmitted through milk from mother to newborns. MMTV encodes a superantigen (SAg) whose activity is indispensable for the virus life cycle, since a genetically engineered virus with a mutation in the sag gene neither amplified in cells of the immune system of suckling pups nor infected their mammary glands. When wild-type MMTV was injected directly into the mammary glands of uninfected pubescent mice, their lymphoid as well as mammary gland cells became virus infected. To test whether this infection of lymphoid cells was dependent on SAg activity and required for virus spread within the mammary gland, we performed mammary gland injections of wild-type MMTV(C3H) into two strains of transgenic mice that lacked SAg-cognate, V beta 14+ T cells. Neither the MTV-ORF or LEL strains showed infection of their mammary glands. Moreover, no MMTV infection of their peripheral lymphocytes was detected. Similar experiments with mice lacking B cells (mu-chain knockouts) showed no detectable virus spread in the mammary glands or lymphoid tissues. These data suggest that SAg activity and MMTV-infected lymphocytes are required, not only for initial steps of viral infection, but also for virus spread within the mammary gland. Virus spread at late times in infection determines whether MMTV induces mammary tumors.     

Neck influences on the spatial properties of vestibulospinal reflexes in decerebrate cats: role of the cerebellar anterior vermis

Ten West African Dwarf (WAD) female goats and twelve Djallonké ewes were artificially infected with a West African strain of Trypanosoma congolense and monitored during 36 weeks over an acute phase (weeks 0-12) and chronic phase (weeks 13-36) to evaluate their haematological and immunological response. Parasitaemia, packed cell volume, red blood cells, haemoglobin, white blood cells and trypanosomal antibodies were assessed. Mean corpuscular volume and mean corpuscular haemoglobin concentration were calculated. The infected animals showed a persistent parasitaemia together with a chronic anaemia and significantly lower packed cell volume, red blood cell count and haemoglobin. The infected sheep developed a macrocytic, hypochromic anaemia during the acute phase changing to normocytic, hypochromic during the chronic phase, whereas, the infected goats developed a normocytic, normochromic anaemia during the acute phase and normocytic, hypochromic during the chronic phase. A significant increase in WBC counts was observed only in the infected sheep during the chronic phase. Trypanosomal antibody titres were significantly higher in the infected sheep than in the infected goats. Both species are regarded as trypanotolerant but Djallonké sheep mount a better haematopoietic and immunological response to infection with T. congolense than WAD goats.     

An immunohistochemical method of detecting Mycoplasma species antigens by use of monoclonal antibodies on paraffin sections of pneumonic bovine and caprine lungs

Lung samples from pneumonic lesions in cattle and goats, naturally or experimentally infected with strains of the Mycoplasma mycoides cluster, were fixed in formalin and embedded in paraffin. An immunohistochemical technique using monoclonal or polyclonal antibodies was performed on tissue sections in order to detect Mycoplasma antigens. Four monoclonal antibodies (MAbs), one (2A3) raised against M. mycoides ssp. mycoides small colony (SC) and large colony (LC), two (1D3 and 5E5) against M. mycoides ssp. capri, and one (5A10) against M. bovis, were used. A range of polyclonal antibodies, raised to the individual subspecies of the M. mycoides cluster, and one to Pasteurella haemolytica, was also used. The MAb 2A3 showed positive immunostaining in lung sections from cattle and goats naturally and experimentally infected with M. mycoides ssp. mycoides SC and LC, but not with pneumonic lesions of cattle and goats due to other members of the M. mycoides cluster, M. bovis or Pasteurella spp. The MAb 1D3 showed immunostaining in lung sections from goats naturally and experimentally infected with M. mycoides ssp. capri, but again not with pneumonic lesions caused by other members of the M. mycoides cluster, M. bovis or Pasteurella spp. The MAb 5E5 immunoreacted in sections from pneumonic lesions from all animals infected with one of the three M. mycoides cluster subspecies used in the study, but not with M. bovis or Pasteurella infected tissue. Immunoreaction was mainly found in the cell debris around necrotic areas, as well as in macrophages, neutrophils and epithelial cells. The localization of antigens of the M. mycoides cluster using polyclonal antisera followed basically the same pattern as that obtained with the monoclonals. However, a wide cross reactivity was found between different antisera and relatively high background immunostaining was also seen, especially in necrotic areas. The results suggest that immunohistochemical methods using monoclonal antibodies are useful tools for the diagnosis and study of the pathogenesis of pneumonia caused by the Mycoplasmas of the M. mycoides cluster.     

Clinical effects of supplemental enteral nutrition solution in severe polytrauma

A clinical, bacteriological, serological and patho-anatomical study was carried out on 12 goats surviving the acute stage of contagious caprine pleuropneumonia (CCPP), experimentally produced with Mycoplasma capricolum ssp. capripneumoniae (M. capripneumoniae), with the major aims of investigating the chronic stage of the disease and elucidating the possibility of a carrier state beyond the acute fulminant phase. The goats were killed 9, 16, 82 or 126 days after the onset of acute clinical signs. On day 9, clinical signs included low grade fever and persistent coughing. Thereafter, only intermittent coughing was recorded. Serum titres of complement-fixing antibodies to M. capripneumoniae were high at the period of fever but dropped thereafter. Post-mortem examination showed acute fibrinous pleuropneumonia on days 9 and 16, and chronic pleuropneumonia on days 82 and 126, including sequester formations in goats killed on day 126. Mycoplasma capripneumoniae was isolated on days 9 and 16 but not on later occasions. The study showed that goats recovered from acute CCPP may have lesions for a long time thereafter but provide no evidence of a carrier state among long-term survivors.     

Role of the insulin-like growth factors and their binding proteins in lactation

Insulin-like growth factor (IGF)-I is thought to mediate a portion of the effects of bST on lactation in dairy cows. Serum concentrations of IGF-I are increased in lactating cows that were treated with bST, and IGF-I receptors are present in bovine mammary tissue. In addition, close arterial infusion of IGF-I into the mammary gland of goats increases milk yield. Little evidence exists to support a direct galactopoietic effect of IGF-I in ruminants. However, IGF-I is a potent mitogen for mammary epithelial cells and may also influence the inhibition of apoptosis of this cell type. The IGF are found in association with a family of individual binding proteins. The high affinity of the IGF for these proteins relative to the IGF receptor allows them to modulate IGF-I bioactivity in the mammary gland at the cellular level. Mammary epithelial cells synthesize multiple forms of IGF binding proteins, and one of these, IGF binding protein-3, is specifically regulated by the IGF. Stimulation of DNA synthesis by IGF-I is enhanced in bovine mammary epithelial cells that overexpress the IGF binding protein-3. These data indicate that IGF-I can stimulate the synthesis of an IGF binding protein, which enhances its own mitogenic activity. However, whether this mechanism is operative in the lactating mammary gland in vivo is unknown. Given the complexity of the interactions between the IGF and their binding proteins, more information is needed before the role of these growth factors in regulating growth, differentiation, and apoptosis of mammary epithelial cells is delineated.     

An entire functional mammary gland may comprise the progeny from a single cell

Any epithelial portion of a normal mouse mammary gland can reproduce an entire functional gland when transplanted into an epithelium-free mammary fat pad. Mouse mammary hyperplasias and tumors are clonal dominant populations and probably represent the progeny of a single transformed cell. Our study provides evidence that single multipotent stem cells positioned throughout the mature fully developed mammary gland have the capacity to produce sufficient differentiated progeny to recapitulate an entire functional gland. Our evidence also demonstrates that these stem cells are self-renewing and are found with undiminished capacities in the newly regenerated gland. We have taken advantage of an experimental model where mouse mammary tumor virus infects mammary epithelial cells and inserts a deoxyribonucleic acid copy(ies) of its genome during replication. The insertions occur randomly within the somatic genome. CzechII mice have no endogenous nucleic acid sequence homology with mouse mammary tumor virus; therefore all viral insertions may be detected by Southern analysis provided a sufficient number of cells contain a specific insertional event. Transplantation of random fragments of infected CzechII mammary gland produced clonal-dominant epithelial populations in epithelium-free mammary fat pads. Serial transplantation of pieces of the clonally derived outgrowths produced second generation glands possessing the same viral insertion sites providing evidence for self-renewal of the original stem cell. Limiting dilution studies with cell cultures derived from third generation clonal outgrowths demonstrated that three multipotent but distinct mammary epithelial progenitors were present in clonally derived mammary epithelial populations. Estimation of the potential number of multipotent epithelial cells that may be evolved from an individual mammary-specific stem cell by self-renewal is in the order of 10(12)-10(13). Therefore, one stem cell might easily account for the renewal of mammary epithelium over several transplant generations.     

Treatment of bovine mastitis with houttuynin sodium bisulphate

Houttuynin sodium bisulphate (HSB), alpha hydroxyl-capryl-ethyl-sodium-sulphonate, is a product formed by reacting sodium bisulphate with houttuynin, which is obtained from a medicinal herb Houttuynia cordata Thunb. From HBS an aqueous intramammary solution was made for the treatment of bovine clinical mastitis. A total of 104 acute and subacute mastitis cases were randomly assigned into two groups with 52 cases in each group: 1. an HSB group in which 80 mg HSB was infused into an affected gland; and 2. a PS group in which intramammary administration of 800,000 i.u. penicillin G in combination with 1 g of streptomycin (PS) was conducted. The treatments were administered twice daily until the inflammatory signs were eliminated and mammary secretion became normal. In acute mastitis, 88.2% (15 of 17) were clinically cured and 52.9% (nine of 17) microbiologically cured by HSB; in the PS group, 90.0% (18 of 20) were clinically cured and 55.0% (11 of 20) microbiologically cured. In subacute cases, the clinical and microbiological cure rates were 94.3% (33 of 35) and 45.7% (16 of 35) respectively, in the HSB group; and in the PS group the clinical and microbiological cure rates were 93.7% (30 of 32) and 43.8% (14 of 32), respectively. No statistically significant difference was found between HSB and PS groups in the treatment of acute as well as subacute mastitis. In addition, an inhibitory effect was found on the growth of lactic streptococcus in the milk collected within 48 h of intramammary treatment with penicillin G in combination with streptomycin. However, for HSB, a mild inhibitory effect on lactic streptococci was detected in the milk within 12 h of treatment.     

Effects of in vitro supplementation with alpha-tocopherol and selenium on bovine neutrophil functions: implications for resistance to mastitis

A low vitamin E/selenium status has been associated with increased vulnerability of dairy cattle to mastitis. Since polymorphonuclear leucocytes (PMN) provide the major cellular defence mechanism within the mammary gland, the effect of in vitro supplementation with vitamin E and selenium on the function of these cells was investigated. Both vitamin E and selenium enhanced the chemotactic and random migration of PMN and increased the production of superoxide following stimulation with phorbol myristate acetate. Vitamin E, but not sodium selenite, was also found to enhance the phagocytosis of opsonised Staphylococcus aureus by PMN. No synergistic effects of the two nutrients were observed. These results obtained in vitro may indicate the potential benefits of in vivo supplementation of dairy cows with vitamin E and selenium in terms of enhancing their natural resistance to mastitis.     

Apical uptake of radiolabelled ochratoxin A into Madin-Darby canine kidney cells

In each of two experiments, the effects of inoculation of Listeria monocytogenes into the ovine mammary gland were studied. In the first experiment, ewes were challenged with one or other of five different Listeria spp. isolates to study differences in their pathogenicity. In the second, ewes were challenged with L. monocytogenes serotype 1/2a to study the sequential features of the infection. The reaction of the mammary glands was assessed by bacteriological, cytological and histological methods. No distinct variation in the pathogenicity of L. monocytogenes isolates was evident: all produced subclinical mastitis, independently of their origin or serotype; a L. innocua isolate caused only a transient increase of milk somatic cell counts. After challenge, L. monocytogenes was isolated for 88 days from the milk of inoculated glands, whose milk somatic cell counts were greater than 1.0 x 10(6) cells ml-1. The organism was also isolated from the mammary lymph nodes, but not from any internal organ of any inoculated ewe. In early stages of the infection neutrophilic infiltration was the predominant histological feature, but hyperaemia, and degeneration of alveolar epithelial cells were also recorded. Later, chronic inflammatory features predominated, with lymphocytes as the principal cell types, destruction of alveoli and fibrous tissue proliferation. In the final stage of the experiment, fibrosis was the salient finding. It is concluded that L. monocytogenes can cause subclinical mastitis after intramammary inoculation into ewes.     

The neonatal Fc receptor is not required for mucosal infection by mouse mammary tumor virus

The milk-borne mouse mammary tumor virus (MMTV) infects newborn mice via the intestine. Infection is initially restricted to Peyer's patches and later spreads to the epithelial cells of the mammary gland. The receptor that mediates uptake and transport of MMTV across the intestinal barrier has not yet been identified, The neonatal Fc receptor (nFcR), which is expressed by enterocytes during the first two weeks of life, is downregulated at weaning, and its disappearance correlates with the onset of intestinal resistance to MMTV. To test whether the nFcR mediates transport and allows infection, we foster nursed on infected MMTV mothers beta2 microglobulin-deficient (beta2m-deficient) newborn mice that are unable to express the nFcR at the surface of their enterocytes. Exposure of beta2m-deficient mice to milk-borne virus resulted in the deletion of peripheral blood T cells reactive to the superantigen encoded by MMTV. Since beta2m-deficient newborn mice are susceptible to MMTV infection despite the lack of the nFcR, we conclude that the nFcR is not required for MMTV transport.     

The secretion of citrate into milk

1. The time course of changes in specific activities of citrate, lactose and fatty acids in milk during frequent milking, following the I.V. administration of labelled glucose, acetate and chylomicrons in goats has been studied. Peak specific activities of lactose and citrate in milk were reached at 2-3 hr, while peak specific activites of fatty acids were reached at 5-7 hr. 2. Following short I.A. infusions of 24Na, 36Cl, and 42K, peak specific activities in milk were reached in 1 hr or less. 3. The mammary epithelium of lactating goats was found to be virtually impermeable to labelled citrate in both directions. 4. Labelled citrate had an apparent volume of distribution in lactating guinea-pigs mammary slices in vitro similar to that of extracellular space markers. 5. Treatment of goats with large doses of oxytocin markedly increased the permeability of the secretory epithelium to labelled citrate. 6. In the goat mammary gland, citrate, protein and calcium failed to enter milk which had been diluted with isosmotic lactose by intraductal injection, whereas Na, K and Cl did enter, thus tending to restore the concentrations of these ions to normal. 7. It is suggested that citrate, which is formed within the sucretory cell, enters milk not by passage across the apical cell membrane but, in common with lactose and milk protein, by exocytosis of Golgi vesicles. It appears that citrate is held at high concentrations in milk by virtue of the impermeability of the mammary epithelium to the forms in which it occurs in milk.     

Potential virulence factors of Streptococcus dysgalactiae associated with bovine mastitis

Mastitis caused by environmental pathogens is a major problem that affects many well-managed dairy herds. Among the environmental pathogens, Streptococcus dysgalactiae is isolated frequently from intramammary infections during lactation and during the nonlactating period. In spite of its high prevalence, little is known about factors that contribute to the virulence of S. dysgalactiae. During the last decade, several cell-associated and extracellular factors of S. dysgalactiae have been identified; yet, the relative importance of these factors in the transmission and pathogenesis of mastitis caused by S. dysgalactiae has not been defined. Streptococcus dysgalactiae can interact with several plasma and extracellular host-derived proteins such as immunoglobulin G, albumin, fibronectin, fibrinogen, collagen, vitronectin, plasminogen, and alpha 2-macroglobulin. These interactions are mediated by bacterial surface proteins. This organism also produces hyaluronidase and fibrinolysin which may be involved in promoting dissemination of the organism into host tissue. Streptococcus dysgalactiae adheres to and is internalized by bovine mammary epithelial cells in vitro. Involvement of host cell kinases, intact microfilaments and de novo eukaryotic protein synthesis are required for internalization of S. dysgalactiae into bovine mammary epithelial cells; a process that appeared to occur by a receptor-mediated endocytosis mechanism. However, de novo bacterial protein synthesis was not required for epithelial cell internalization. Furthermore, S. dysgalactiae survived within mammary epithelial cells for extended periods of time without losing viability or damaging the eukaryotic cell. Further research on characterization of host-pathogen interactions that take place during the early stages of mammary gland infection will enhance our understanding of pathogenesis of intramammary infection which may contribute to development of methods to minimize production losses due to mastitis.     

Temperature correction of blood gas values

Biotinylated riboprobe that specifically hybridized with messenger RNAs (mRNAs) encoding the long form of prolactin receptor (PRLRL) was transcribed from 269 bp Hind III and Xho I fragment of the cytoplasmic domain of PRLRL complementary DNA (cDNA). The probe was used for in situ hybridization to identify tissue localization of PRLRL mRNA in the mammary gland, liver, ovaries and kidneys from lactating rats at 24-36 h after delivery. Histochemical detection of signals by means of horseradish peroxidase (HRP)-labeled streptavidin revealed that the PRLRL gene was expressed on the alveolar epithelial cells and mammary ductal epithelium in the mammary gland, and hepatocytes in the liver. In the ovary, the PRLRL gene was expressed on the luteal cells in the newly formed corpus luteum, granulosa cells and theca cells of follicles at various stages of development, hypertrophied theca cells in the atretic follicle, and secondary interstitial cells, but no signal was observed in the kidney. Biotinylated sense RNA probe did not detect any signals in any of the tissues examined. In situ hybridization with non-radiolabeled probe provided the identification of PRLRL mRNA in the fine tissues, such as follicular epithelium in the ovary, and showed the morphology of individual cells expressing the PRLRL gene. In particular, the diversity of signal intensity in the same mammary gland with different appearances suggested the existence of a local mechanism controlling PRLRL gene expression.