Observations about declining fertility in a feline breeding colony

Feline breeding colonies are important to the feline industry by preserving traits desirable for a particular breed or in research settings by maintaining medically valuable genetic traits. As breeding females age, their reproductive efficiency declines. The objective of this study was to determine the most common causes of infertility in breeding females that were producing fewer kittens. Knowing the cause and average age of infertility would allow management decisions to be made for the betterment of the colony. The medical records of 70 queens retired from breeding from a single research colony were examined for litter size and number, fertility over their lifespan, and age and reason for removal from breeding stock. Sections of uterus and ovaries were evaluated using gross and histopathological examination for a subset of these queens (46). The data suggests that mature, continuously breeding female cats may show signs of reduced fertility (infertile matings or reduced litter size) as early as 3 years of age and may be a result of undiagnosed Cystic Endometrial Hyperplasia (CEH), endometritis, pyometra and/or ovarian cysts. Evaluation of breeding queens should include periodic ultrasounds to monitor for ovarian cysts and evidence of CEH. Retiring animals from breeding once signs of infertility become apparent is recommended.

Unilateral vascular hamartomas of the vaginal tunic in a dog

A 12-y-old, male Dachshund was presented for elective orchiectomy. The testes were of normal size. The left testis had numerous dark-red, blood clot-like foci within the vaginal tunic over the pampiniform plexus, epididymis, and testis. Histologically, the red foci were limited to the vaginal tunic and consisted of disorderly growing, variably sized, thin-walled blood vessels lined by a single layer of endothelial cells without mitoses and supported by a thin layer of pericytes. The blood vessels were distended by erythrocytes without thrombus formation. Endothelial cells had cytoplasmic immunolabeling for CD31; pericytes had strong cytoplasmic immunolabeling for α-smooth muscle actin. Our case of subclinical unilateral vascular hamartomas of the vaginal tunic in a dog has not been reported previously in domestic animals or humans, to our knowledge.

Enhanced Protection by Recombinant Newcastle Disease Virus Expressing Infectious Bronchitis Virus Spike Ectodomain and Chicken Granulocyte-Macrophage Colony-Stimulating Factor

We previously reported that recombinant Newcastle disease virus LaSota (rLS) expressing infectious bronchitis virus (IBV) Arkansas (Ark)-type trimeric spike (S) ectodomain (Se; rLS/ArkSe) provides suboptimal protection against IBV challenge. We have now developed rLS expressing chicken granulocyte-macrophage colony-stimulating factor (GMCSF) and IBV Ark Se in an attempt to enhance vaccine effectiveness. In the current study, we first compared protection conferred by vaccination with rLS/ArkSe and rLS/ArkSe.GMCSF. Vaccinated chickens were challenged with virulent Ark, and protection was determined by clinical signs, viral load, and tracheal histomorphometry. Results showed that coexpression of GMCSF and the Se from rLS significantly reduced tracheal viral load and tracheal lesions compared with chickens vaccinated with rLS/ArkSe. In a second experiment, we evaluated enhancement of cross-protection of a Massachusetts (Mass) attenuated vaccine by priming or boosting with rLS/ArkSe.GMCSF. Vaccinated chickens were challenged with Ark, and protection was evaluated. Results show that priming or boosting with the recombinant virus significantly increased cross-protection conferred by Mass against Ark virulent challenge. Greater reductions of viral loads in both trachea and lachrymal fluids were observed in chickens primed with rLS/ArkSe.GMCSF and boosted with Mass. Consistently, Ark Se antibody levels measured with recombinant Ark Se protein-coated ELISA plates 14 days after boost were significantly higher in these chickens. Unexpectedly, the inverse vaccination scheme, that is, priming with Mass and boosting with the recombinant vaccine, proved somewhat less effective. We concluded that a prime and boost strategy by using rLS/ArkSe.GMCSF and the worldwide ubiquitous Mass attenuated vaccine provides enhanced cross-protection. Thus, rLS/GMCSF coexpressing the Se of regionally relevant IBV serotypes could be used in combination with live Mass to protect against regionally circulating IBV variant strains.

Hepatic Perisinusoidal Myofibroblast Proliferation and Systemic Inflammatory Response Precedes Sep/Tox Hepatitis in Broilers

Septicemia-toxemia (sep/tox) falls under U.S. Department of Agriculture (USDA) food safety Category 1 and is the most common and economically significant cause of broiler carcass condemnations. Hepatic lesions are considered a possible consequence of septicemia and associated bacterial contamination of the carcass. Thus, these lesions are considered an indicator of sep/tox (sep/tox hepatitis). This study was undertaken to analyze the histologic lesions preceding grossly visible liver lesions leading to condemnation because of sep/tox at the processing plant. Livers from carcasses of broilers condemned by USDA inspectors for sep/tox were used to establish microscopic and gross criteria of end-stage sep/tox hepatitis. Following the characterization of sep/tox hepatitis, broilers from a farm with a history of sep/tox condemnations were submitted for postmortem examination and bacteriologic investigation at four intervals during the final 20 days of production. Five healthy and five clinically ill chickens were submitted from four houses at 18, 25, 32, and 38 days of production (160 total). Microscopic lesions representing hepatic perisinusoidal myofibroblast proliferation (HPMP), periportal extramedullary granulopoiesis (PEMG), splenic follicular histiocytosis, and bone marrow cellularity (BMC) were graded subjectively for each bird, and subjective grading was evaluated with digital quantitative techniques. Perisinusoidal hepatic stellate cell morphology and progressive transformation of these cells into myofibroblasts was confirmed by immunohistochemistry for smooth muscle actin and desmin. Aerobic cultures of livers and gall bladders from sep/tox birds yielded no growth of bacteria associated with septicemia. Mild to severe HPMP was observed in all age groups, representing 28% of examined birds. Increases in inflammatory cells observed by PEMG and BMC were positively correlated with progressive HPMP and end-stage sep/tox hepatitis in broiler chickens.

Dermatophytic pseudomycetomas in two ferrets (Mustela putorius furo)

BACKGROUND

Dermatophytic pseudomycetoma is an atypical form of dermatophytosis where the infection is located in the deep dermal and subcutaneous tissues. Although rare, it is most commonly associated with Microsporum canis or Trichophyton sp. It has been reported in cats, dogs and horses.

OBJECTIVES

To describe the clinical and pathological findings of dermatophytic pseudomycetoma caused by M. canis and Trichophyton sp. in two domestic ferrets.

ANIMALS

Two pet ferrets (Mustela putorius furo).

METHOD AND MATERIALS

Case report.

RESULTS

Two ferrets were diagnosed with dermatophytic pseudomycetoma confirmed by histological examination of tissue and fungal culture. In both cases, ferrets presented with several cutaneous firm nodules 0.6-3 cm in diameter. Microscopic lesions revealed multifocal nodular pyogranulomatous inflammation with intralesional fungi.

CONCLUSIONS AND CLINICAL IMPORTANCE

To the best of the authors' knowledge, this is the first description of dermatophytic pseudomycetoma in domestic ferrets. This disease should be included in the differential diagnosis of nodular dermatopathies in this species.

Kidney Cell-Adapted Infectious Bronchitis Virus Arkansas Delmarva Poultry Industry Vaccine Confers Effective Protection Against Challenge

We previously demonstrated that adaptation of an embryo-attenuated infectious bronchitis virus (IBV) Arkansas Delmarva Poultry Industry (ArkDPI)-derived vaccine to chicken embryo kidney (CEK) cells shifted the virus population towards homogeneity in spike (S) and nonstructural protein genes. Moreover, the typical Ark vaccine subpopulations emerging in chickens vaccinated with commercial Ark vaccines were not detected in chickens vaccinated with the CEK-adapted virus. In this study, chickens vaccinated with a low dose (1.6 × 10(3) EID50/bird, where EID50 is 50% embryo infectious dose) of CEK-adapted Ark vaccine at 5 days of age showed a significant reduction of IBV RNA in lachrymal fluids and decreased incidence of IBV RNA detection in tracheal swabs 5 days after challenge compared to unvaccinated challenged chickens. In a second experiment, 5-day-old chickens were vaccinated with 10(4) or 10(5) EID50/chicken of CEK-adapted Ark vaccine, and protection was compared to chickens vaccinated with 10(5) EID50/chicken of the commercial ArkDPI-derived vaccine from which the CEK-adapted virus originated. All vaccinated chicken groups showed a significant reduction of respiratory signs and viral load 5 days after Ark virulent challenge compared to unvaccinated challenged controls. No viral subpopulations different from the challenge virus were detected in chickens vaccinated with CEK-Ark after challenge. In contrast, IBV S1 sequences differing from the predominant population in the challenge virus were detected in several chickens vaccinated with the commercial Ark attenuated vaccine. From an applied perspective, the CEK-adapted IBV ArkDPI-derived vaccine is an improved and effective vaccine candidate with which to protect chickens against virulent Ark-type strains.

Hemoabdomen secondary to high grade lymphoma

A 10-year-old castrated male Labrador retriever dog was presented for evaluation of a right elbow mass. Mandibular lymphadenopathy was noted on physical examination. Following sudden death after discharge, a necropsy was performed. Cause of death was determined to be due to hemoabdomen secondary to high grade lymphoma.

Acute renal failure in 2 adult llamas after exposure to Oak trees (Quercus spp.)

Two adult llamas (Lama glama) previously exposed to oak trees (Quercus spp.) were presented with a history of depression and anorexia. Clinicopathological abnormalities included severe gastroenteritis, acute renal failure, and increased liver enzymes. This is believed to be the first report of oak toxicosis in South American camelids.

Dictyostelium discoideum mutants with conditional defects in phagocytosis

We have isolated and characterized Dictyostelium discoideum mutants with conditional defects in phagocytosis. Under suspension conditions, the mutants exhibited dramatic reductions in the uptake of bacteria and polystyrene latex beads. The initial binding of these ligands was unaffected, however, indicating that the defect was not in a plasma membrane receptor: Because of the phagocytosis defect, the mutants were unable to grow when cultured in suspensions of heat-killed bacteria. The mutants exhibited normal capacities for fluid phase endocytosis and grew as rapidly as parental (AX4) cells in axenic medium. Both the defects in phagocytosis and growth on bacteria were corrected when the mutant Dictyostelium cells were cultured on solid substrates. Reversion and genetic complementation analysis suggested that the mutant phenotypes were caused by single gene defects. While the precise site of action of the mutations was not established, the mutations are likely to affect an early signaling event because the binding of bacteria to mutant cells in suspension was unable to trigger the localized polymerization of actin filaments required for ingestion; other aspects of actin function appeared normal. This class of conditional phagocytosis mutant should prove to be useful for the expression cloning of the affected gene(s).

Cell attachment and entry by Toxoplasma gondii

Toxoplasma gondii is a ubiquitous protozoan parasite capable of invading and surviving within nearly all nucleated cells. Our studies focused on the ligands and receptors mediating parasite attachment to target cells and upon the mechanisms for evasion of intracellular killing once cell invasion is completed. The invasive tachyzoite stage attaches to beta 1 integrins on fibroblasts. Attachment is mediated in part by laminin on the parasite surface, which bridges parasite and cell laminin receptors. The widespread distribution of beta 1 integrins and laminin facilitate tachyzoite invasion of a broad variety of target cells. Active entry of T. gondii into fibroblasts results in formation of parasitophorous vacuoles which are incapable of fusing with any intracellular organelle. The block in fusion is overcome when antibody coated parasites are phagocytosed by fibroblasts stably transfected with murine Fc receptors, indicating that route of parasite entry determines fusion competence of the vacuole.

The human mannose-binding protein functions as an opsonin

The human mannose-binding protein (MBP) is a multimeric serum protein that is divided into three domains: a cysteine-rich NH2-terminal domain that stabilizes the alpha-helix of the second collagen-like domain, and a third COOH-terminal carbohydrate binding region. The function of MBP is unknown, although a role in host defense is suggested by its ability to bind yeast mannans. In this report we show that native and recombinant human MBP can serve in an opsonic role in serum and thereby enhance clearance of mannose rich pathogens by phagocytes. MBP binds to wild-type virulent Salmonella montevideo that express a mannose-rich O-polysaccharide. Interaction of MBP with these organisms results in attachment, uptake, and killing of the opsonized bacteria by phagocytes. These results demonstrate that MBP plays a role in first line host defense against certain pathogenic organisms.

Developmentally regulated expression by Trypanosoma cruzi of molecules that accelerate the decay of complement C3 convertases

We recently showed that culture-derived metacyclic trypomastigotes (CMT), but not epimastigotes (Epi), of the Miranda 88 strain of Trypanosoma cruzi evade lysis by the human alternative complement pathway because of inefficient binding of factor B to complement component C3b on the parasite surface. These results suggested that CMT and tissue-culture-derived trypomastigotes (TCT), which also activate the alternative pathway poorly, might produce a molecule capable of interfering with factor B binding to C3b. We now demonstrate that CMT and TCT lysates, as well as molecules spontaneously shed from CMT and TCT but not Epi, accelerate decay of 125I-labeled factor Bb from the alternative-pathway C3 convertase (C3bBb) assembled on zymosan or Epi and also accelerate decay of the classical-pathway C3 convertase (C4b2a) on sheep erythrocytes. Parasites metabolically labeled with [35S]methionine spontaneously shed a limited number of radioactive components ranging in molecular mass from 86 to 155 kDa for trypomastigotes and 25 to 80 kDa for Epi. Decay-accelerating activity within supernatants is inactivated by papain and is coeluted with 35S-containing polypeptides on FPLC anion-exchange chromatography, suggesting that the active constituents are protein molecules. Molecules with decay-accelerating activity may explain the developmentally regulated resistance to complement-mediated lysis in infective and vertebrate stages of the T. cruzi life cycle.

The function of antibody and complement in the lysis of bacteria

The factors controlling lysis of gram-negative bacteria by complement are being investigated systematically. The first question was how smooth Salmonella minnesota, which has on its surface lipopolysaccharide with long O polysaccharide side chains, avoids lysis. Rough organisms are serum sensitive. In both smooth and rough organisms, complement components are deposited on the surface and the lytic sequence proceeds to completion. However, with serum-resistant organisms the membrane attack complex (MAC), composed of late-acting complement proteins, does not successfully insert into the outer membrane to cause membrane damage. At the completion of the lytic sequence, the hydrophobic MAC is shed. C3b, which directs late component assembly, is deposited on the longest O polysaccharide side chains on these smooth organisms, where it does not direct successful insertion of the MAC into the outer membrane. Serum-resistant gonococci sequester the MAC on the organism's surface in association with specific outer membrane components, where it does no damage to the outer membrane. Antibody appears to mediate site-directed complement component deposition in a number of systems. Thus, depending on antibody specificity, complement may be deposited on the organism's surface to cause successful complement attack or may block complement attack induced by bactericidal antibody. Monoclonal antibodies of the same isotype directed at different epitopes on the same bacterial surface antigen may either induce lysis or block lytic attack.

Characterization of protein I from serum-sensitive and serum-resistant transformants of Neisseria gonorrhoeae

The protein IAs of serum-sensitive (FA635) and serum-resistant (FA638) transformants of Neisseria gonorrhoeae, which have identical pedigrees, have been shown to be different by the use of a monoclonal antibody and were also shown to be different by proteinase K cleavage and primary structural and surface peptide mapping. The difference in structure is within the surface-exposed region of the molecule. The only other difference observed between the two strains was a very slight difference in lipooligosaccharide silver staining in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These data suggest that protein I alone or in combination with lipooligosaccharide may significantly contribute to serum resistance.

Evasion of the alternative complement pathway by metacyclic trypomastigotes of Trypanosoma cruzi: dependence on the developmentally regulated synthesis of surface protein and N-linked carbohydrate

Epimastigotes (EPI) of Trypanosoma cruzi are highly sensitive to lysis in fresh normal human serum by the alternative complement pathway (ACP). In contrast, metacyclic trypomastigotes (CMT) derived from EPI in stationary culture fail to activate the ACP and are thus resistant to serum-mediated lysis. To investigate the nature of the parasitic surface molecules which enable infective metacyclic trypomastigotes to evade the ACP, CMT were treated with a variety of different proteolytic and glycosidic enzymes, and their sensitivity to ACP-dependent lysis was tested. Pretreatment with pronase was found to cause a near complete reversal in the resistance of CMT to serum lysis, whereas trypsin or chymotrypsin induced smaller increases in complement sensitivity. Similarly, pretreatment with N-glycanase or neuraminidase also partially abrogated the resistance of CMT to ACP-dependent lysis. The effect of these enzymes on susceptibility to complement-mediated lysis was paralleled in increased C3 and C9 deposition on the organism. In addition, electrophoretic analysis of parasite-bound C3 indicated that the hemolytically inactive fragment, iC3b, was the major form of the molecule on CMT, while the hemolytically active fragment, C3b, predominated on pronase-treated CMT. Furthermore, when C3 was deposited on the parasite surface by means of purified ACP components, 80% of C3b on pronase-pretreated CMT but only 14% of the C3b on CMT bound the amplification protein factor B with high affinity, a prerequisite for efficient ACP activation. When cultured at 37 degrees C after pronase treatment, CMT gradually regained their resistance to ACP-mediated lysis. This process was blocked if puromycin, cycloheximide, or tunicamycin were included in the culture medium. The above findings suggest that evasion of the ACP by CMT is dependent on the developmentally regulated synthesis of protein as well as N-linked carbohydrate chains. A stage-specific 90,000 to 115,000 m.w. glycoprotein doublet present on the surface of CMT was shown to be uniquely sensitive to pronase digestion. Thus, this complex, which is also recognized by a CMT-specific monoclonal antibody, may be the glycoprotein component responsible for control of ACP activation

Evasion of the alternative complement pathway by metacyclic trypomastigotes of Trypanosoma cruzi: dependence on the developmentally regulated synthesis of surface protein and N-linked carbohydrate

Epimastigotes (EPI) of Trypanosoma cruzi are highly sensitive to lysis in fresh normal human serum by the alternative complement pathway (ACP). In contrast, metacyclic trypomastigotes (CMT) derived from EPI in stationary culture fail to activate the ACP and are thus resistant to serum-mediated lysis. To investigate the nature of the parasitic surface molecules which enable infective metacyclic trypomastigotes to evade the ACP, CMT were treated with a variety of different proteolytic and glycosidic enzymes, and their sensitivity to ACP-dependent lysis was tested. Pretreatment with pronase was found to cause a near complete reversal in the resistance of CMT to serum lysis, whereas trypsin or chymotrypsin induced smaller increases in complement sensitivity. Similarly, pretreatment with N-glycanase or neuraminidase also partially abrogated the resistance of CMT to ACP-dependent lysis. The effect of these enzymes on susceptibility to complement-mediated lysis was paralleled in increased C3 and C9 deposition on the organism. In addition, electrophoretic analysis of parasite-bound C3 indicated that the hemolytically inactive fragment, iC3b, was the major form of the molecule on CMT, while the hemolytically active fragment, C3b, predominated on pronase-treated CMT. Furthermore, when C3 was deposited on the parasite surface by means of purified ACP components, 80% of C3b on pronase-pretreated CMT but only 14% of the C3b on CMT bound the amplification protein factor B with high affinity, a prerequisite for efficient ACP activation. When cultured at 37 degrees C after pronase treatment, CMT gradually regained their resistance to ACP-mediated lysis. This process was blocked if puromycin, cycloheximide, or tunicamycin were included in the culture medium. The above findings suggest that evasion of the ACP by CMT is dependent on the developmentally regulated synthesis of protein as well as N-linked carbohydrate chains. A stage-specific 90,000 to 115,000 m.w. glycoprotein doublet present on the surface of CMT was shown to be uniquely sensitive to pronase digestion. Thus, this complex, which is also recognized by a CMT-specific monoclonal antibody, may be the glycoprotein component responsible for control of ACP activation

Evasion of alternative complement pathway by Trypanosoma cruzi results from inefficient binding of factor B

During its differentiation in the insect vector to a stage infective for the mammalian host, Trypanosoma cruzi becomes resistant to lysis by the alternative pathway of complement. To elucidate the mechanism of complement evasion, we studied control of complement activation on the surface of the noninfective epimastigote and the infective culture-derived metacyclic trypomastigote stages (CMT) of T. cruzi. It was found that the predominant form of complement component C3 on epimastigotes is C3b, whereas the majority of C3 on CMT is in the form of the hemolytically inactive fragment iC3b, which cannot participate in C5 convertase formation or lead to deposition of the lytic C5b-9 complex. Our results also showed that C3 binds by a covalent ester linkage to surface molecules of different molecular weight in the epimastigote stage and CMT. Binding studies with purified complement components indicated that CMT do not support efficient formation of an alternative pathway C3 convertase. C3b on the parasite surface fails to bind the amplification component, factor B, rather than showing enhanced binding of the control component, factor H. These results identify the biochemical basis for evasion of complement-mediated killing in T. cruzi and reveal a mechanism for developmental regulation of complement activation.

gp72, the 72 kilodalton glycoprotein, is the membrane acceptor site for C3 on Trypanosoma cruzi epimastigotes

We examined the interaction of complement component C3 with surface molecules on Trypanosoma cruzi. Five- to six-fold more C3 was bound to epimastigotes (Epi) than to metacyclic trypomastigotes (CMT) of strain M88. Epi and CMT were surface iodinated, then incubated in C8-deficient serum, and detergent lysates were applied to anti-C3 antibody that had been coupled to Sepharose. We found that 9.20-10.24% of applied 125I-Epi protein bound to anti-C3-sepharose, compared to 2.64% binding of 125I-CMT protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that C3 was attached to 125I-Epi protein by a covalent bond. Samples eluted from anti-C3-sepharose with hydroxylamine revealed a single, major, 72 kD band, suggesting that C3b attaches almost exclusively to the 72 kD glycoprotein of Epi by a hydroxylamine-susceptible ester bond. An antiserum was prepared from lysates of serum-treated Epi that had been affinity-purified on anti-C3-sepharose. This antiserum immunoprecipitated a single 72 kD component (gp72) from surface-iodinated Epi, and specifically recognized only gp72 from Epi in immunoblots. In contrast to the results with Epi, gp72 on CMT was not found to be an efficient acceptor molecule for C3 deposition. The results are the first to evaluate the acceptor site for C3 deposition on a parasite, and they show that gp72 on Epi, but not gp72 on CMT, serves as the preferential acceptor for C3 during antibody-independent alternative complement pathway activation.

Serum-resistant mutants of Escherichia coli O111 contain increased lipopolysaccharide, lack an O antigen-containing capsule, and cover more of their lipid A core with O antigen

Escherichia coli strains of group O111 were characterized with respect to sensitivity to complement killing, amount of lipopolysaccharide and O antigen-containing capsule, and distribution of O antigen. All wild-type E. coli O111 strains were resistant to complement killing in the absence of specific antibody. Presensitization of strains with antibody to whole cells (OK antibody), followed by incubation in 50% pooled normal human serum as a source of complement, subdivided wild-type strains into three types: completely resistant, partially resistant, and sensitive. Completely and partially resistant mutants were isolated by cycles of serum killing, starting with one sensitive strain. Completely resistant mutants had no O antigen-containing capsule, but had 50% more lipopolysaccharide than did the parent, and this lipopolysaccharide had 30% fewer lipid A core molecules devoid of O antigen. Partially resistant mutants still had O antigen-containing capsule, but contained 40% more lipopolysaccharide than did the parent; the extent of coverage of lipid A core with O antigen remained unchanged. No correlations were found between outer membrane protein composition and the degree of serum resistance. Since the terminal membrane attack complex (C5b-9) must stably insert into a hydrophobic membrane site to effect killing, we conclude that both increased lipid A core and increased coverage of lipid A core with O antigen preclude access of C5b-9 to lethal sites on the cell surface.

Serum sensitivity of Neisseria gonorrhoeae: the role of lipopolysaccharide

A lipopolysaccharide (LPS) mutant (FA5100) of a serum-resistant strain of Neisseria gonorrhoeae (FA19) was found to be highly sensitive to the bactericidal activity of normal human serum (NHS). Both strain FA5100 and an unrelated serum-sensitive clinical isolate (F62) were killed by NHS via the classical complement pathway since killing required C2 and Ca++. However, the fact that only strain FA5100 was sensitive to human hypogammaglobulinemic and cord serum suggested that this strain might activate the classical complement pathway in the absence of antibody. Anticomplementary concentrations of LPS from strain FA5100 inhibited the bactericidal activity of NHS against either strain FA5100 or strain F62. However, concentrations of LPS from strain FA5100 that exhibited marginal anticomplementary behavior also inhibited the killing of strain F62 by NHS. The ability of LPS from strain FA5100 to inhibit the bactericidal activity of NHS against strain FA5100 and to activate complement was reduced by treatment with mild alkali. However, alkali-treated LPS from strain FA5100 still inhibited the bactericidal activity of NHS against strain F62.

The biologic activity of mast cell granules. IV. The effect of complement depletion on rat cutaneous late phase reactions

Cutaneous late phase reactions (LPR) in rats can be induced by the intradermal injection of anti-IgE antibody or isolated rat peritoneal mast cell granules. Rat LPR are characterized by neutrophil-rich infiltrates at 2 to 8 hr followed by mononuclear cell-rich infiltrates thereafter. Rat Arthus reactions are histologically similar and are complement (C) dependent. To determine the importance of C in the pathogenesis of rat LPR compared with its role in Arthus reactions, rats were treated with cobra venom factor (CVF) (250 U/kg i.v.), and the effects of this treatment on total hemolytic complement (CH50), C3 titers, LPR, and Arthus reactions were assessed. CVF treatment produced profound decreases in both CH50 (from 197 +/- 20 to less than 1.0 U/ml) and C3 (from 44,240 +/- 2840 to less than 5 U/ml) titers after 6 hr, which persisted through at least 30 hr. The inflammatory intensity of heterologous reverse passive Arthus reactions was significantly decreased in CVF-treated animals. In contrast, the intensity of LPR was unaffected by CVF treatment. Therefore, although LPR and Arthus reactions share certain histologic characteristics, these similarities are not due to a mutual requirement for the presence of C.

The biologic activity of mast cell granules. IV. The effect of complement depletion on rat cutaneous late phase reactions

Cutaneous late phase reactions (LPR) in rats can be induced by the intradermal injection of anti-IgE antibody or isolated rat peritoneal mast cell granules. Rat LPR are characterized by neutrophil-rich infiltrates at 2 to 8 hr followed by mononuclear cell-rich infiltrates thereafter. Rat Arthus reactions are histologically similar and are complement (C) dependent. To determine the importance of C in the pathogenesis of rat LPR compared with its role in Arthus reactions, rats were treated with cobra venom factor (CVF) (250 U/kg i.v.), and the effects of this treatment on total hemolytic complement (CH50), C3 titers, LPR, and Arthus reactions were assessed. CVF treatment produced profound decreases in both CH50 (from 197 +/- 20 to less than 1.0 U/ml) and C3 (from 44,240 +/- 2840 to less than 5 U/ml) titers after 6 hr, which persisted through at least 30 hr. The inflammatory intensity of heterologous reverse passive Arthus reactions was significantly decreased in CVF-treated animals. In contrast, the intensity of LPR was unaffected by CVF treatment. Therefore, although LPR and Arthus reactions share certain histologic characteristics, these similarities are not due to a mutual requirement for the presence of C.

Studies on the mechanism of bacterial resistance to complement-mediated killing. III. C5b-9 deposits stably on rough and type 7 S. pneumoniae without causing bacterial killing

Gram-positive cocci resist direct killing by serum. The mechanism of resistance was studied by measuring consumption of terminal complement components from serum and uptake of purified, radiolabeled C7 and C9 on rough and encapsulated type 7 Streptococcus pneumoniae. Extensive consumption of C5, C7, and C9 occurred when 5 X 10(8) rough or type 7 pneumococci were incubated for 1 hr in 10% pooled normal human serum (PNHS). Approximately 10,000 molecules of C7 and C9 bound per organism during the same period of incubation. Twenty to 30% of C7 and C9 was released from rough organisms. Release was not due to autolysis since it occurred with glutaraldehyde-fixed organisms as well as in S. pneumoniae that were rendered resistant to autolysis by growth in ethanolamine. Between 10 and 30% of bound 125IC9 counts were eluted from the rough and type 7 organisms by incubation in 1 M NaCl or 0.01 M EDTA, which suggests that bound C5b-9 was not attached by predominantly ionic interactions. Elution of 44 to 74% of 125IC9 from live and glutaraldehyde-fixed organisms by 1% sodium deoxycholate suggests that hydrophobic bonds are involved in C5b-9 attachment. Trypsin cleaved 67 and 55% of 125IC9 counts from live rough and type 7 S. pneumoniae, respectively which indicates that the bound complex is not protected by the cell wall from proteolytic attack. Serum resistance in S. pneumoniae does not represent a failure to form C5b-9 on the bacterial cell wall but apparently reflects a failure of the bound complex to penetrate the thick peptidoglycan layer.

Relative efficacy and critical interval of antimicrobial agents in experimental infections involving bacteroides fragilis

Activity of seven antimicrobial agents was examined using a mouse model of a subcutaneous infection that involved Bacteroides fragilis. Untreated mice had encapsulated abscesses with approximately 10(10) bacteria. Pharmacokinetic studies showed that all drugs tested penetrated into abscesses to provide mean peak levels that were 17% to 53% of mean peak serum levels. In vivo efficacy v 15 strains was measured by the reduction in counts of viable organisms when treatment was initiated one hour after challenge. This showed that the most active agents, in order of activity, were metronidazole hydrochloride, clindamycin phosphate, moxalactam disodium, and cefoxitin sodium. A delay in treatment of eight to 120 hours after challenge showed a noticeable reduction in activity, except with metronidazole. It is presumed that bacteria within an abscess are in a stationary growth phase, and this has an important influence on in vivo efficacy.

Studies on the mechanism of bacterial resistance to complement-mediated killing. III. C5b-9 deposits stably on rough and type 7 S. pneumoniae without causing bacterial killing

Gram-positive cocci resist direct killing by serum. The mechanism of resistance was studied by measuring consumption of terminal complement components from serum and uptake of purified, radiolabeled C7 and C9 on rough and encapsulated type 7 Streptococcus pneumoniae. Extensive consumption of C5, C7, and C9 occurred when 5 X 10(8) rough or type 7 pneumococci were incubated for 1 hr in 10% pooled normal human serum (PNHS). Approximately 10,000 molecules of C7 and C9 bound per organism during the same period of incubation. Twenty to 30% of C7 and C9 was released from rough organisms. Release was not due to autolysis since it occurred with glutaraldehyde-fixed organisms as well as in S. pneumoniae that were rendered resistant to autolysis by growth in ethanolamine. Between 10 and 30% of bound 125IC9 counts were eluted from the rough and type 7 organisms by incubation in 1 M NaCl or 0.01 M EDTA, which suggests that bound C5b-9 was not attached by predominantly ionic interactions. Elution of 44 to 74% of 125IC9 from live and glutaraldehyde-fixed organisms by 1% sodium deoxycholate suggests that hydrophobic bonds are involved in C5b-9 attachment. Trypsin cleaved 67 and 55% of 125IC9 counts from live rough and type 7 S. pneumoniae, respectively which indicates that the bound complex is not protected by the cell wall from proteolytic attack. Serum resistance in S. pneumoniae does not represent a failure to form C5b-9 on the bacterial cell wall but apparently reflects a failure of the bound complex to penetrate the thick peptidoglycan layer.

Comparative efficacy of 10 antimicrobial agents in experimental infections with Bacteroides fragilis

The comparative efficacy of 10 antimicrobial agents against 15 strains of Bacteroides was examined in vivo using an experimental model of subcutaneous abscesses in mice. Results were evaluated by bacterial counts per lesion with the antimicrobial agents administered beginning 1 hr after challenge. Six drugs reduced counts (mean +/- SEM log decrease) significantly compared with values in untreated control animals: metronidazole, 6.7 +/- 0.6; clindamycin, 5.0 +/- 0.6; moxalactam, 3.8 +/- 0.5; cefoxitin, 3.5 +/- 0.5; chloramphenicol, 1.6 +/- 0.5; and carbenicillin, 1.0 +/- 0.3. Antimicrobial agents that had no significant effect compared with values in untreated control animals were cephalothin, cefoperazone, ceforanide, and rosaramicin. Evaluation of several parameters based on in vitro activity and pharmacokinetic properties at the infected site indicated that the time during which the level of antimicrobial agent exceeded the minimal inhibitory concentration correlated best with in vivo antibacterial activity. A delay in the time that treatment was initiated resulted in a marked reduction in in vivo activity.