The relationship between an endangered North American tree and an endophytic fungus

BACKGROUND

The Florida torreya (Torreya taxifolia) began a catastrophic decline in the late 1950s and is now the rarest tree in North America for which a full species designation has been established. The trees have common plant disease symptoms, but the reason for the decline has never been identified. T. taxifolia's imminent extinction gains special poignancy through its close relationship to the Pacific yew (Taxus brevifolia), which produces the potent anticancer agent, taxol.

RESULTS

An examination of the endophytic fungal communities of wild torreyas consistently found a filamentous fungus, Pestalotiopsis microspora, associated with diseased trees and also with most symptomless trees. P. microspora can be cultured in the laboratory, and when it is introduced into greenhouse-grown torreyas, it causes disease symptoms similar to those seen in the field. The fungus can then be reisolated from these deliberately infected trees. The phytotoxins pestalopyrone, hydroxypestalopyrone and pestaloside have been isolated and characterized from axenic fungal cultures, and both pestalopyrone and hydroxypestalopyrone can be isolated from artificially infected torreyas. In addition, pestaloside has antifungal activity against other fungal endophytes of T. taxifolia.

CONCLUSIONS

The filamentous fungus, P. microspora, has an endophytic-pathologic relationship with T. taxifolia. The fungus resides in the inner bark of symptomless trees, and physiological or environmental factors could trigger its pathological activity. P. microspora produces the phytotoxins pestalopyrone, hydroxypestalopyrone, and pestaloside which give rise to the disease. Pestaloside, which also has antifungal activity, could reduce competition from other fungal endophytes within the host.

Identification of a Drosophila muscle development gene with structural homology to mammalian early growth response transcription factors

In Drosophila, stripe (sr) gene function is required for normal muscle development. Some mutations disrupt embryonic muscle development and are lethal. Other mutations cause total loss of only a single muscle in the adult. Molecular analysis shows that sr encodes a predicted protein containing a zinc finger motif. This motif is homologous to the DNA binding domains encoded by members of the early growth response (egr) gene family. In mammals, expression of egr genes is induced by intercellular signals, and there is evidence for their role in many developmental events. The identification of sr as an egr gene and its pattern of expression suggest that it functions in muscle development via intercellular communication.

Application of ABO genotyping using polymerase chain reaction method to assess engraftment in bone marrow transplantation--a case report

We described a case of acute promyelocytic leukemia with O blood type who received bone marrow transplantation during a second remission from his HLA identical, B blood type sibling. Using PCR genotyping of the ABO group and analysis of the variable number of tandem repeats of the D1S80 locus, we could quickly document the successful early engraftment in this patient. We emphasize that the use of PCR ABO genotyping is a quick and valuable method which could be applied to assess the engraftment and its follow up in those transplant cases with donors of mismatched blood groups.

Myeloma Ig heavy chain V region sequences reveal prior antigenic selection and marked somatic mutation but no intraclonal diversity

The lg VH region sequence in 48 patients with multiple myeloma (MM) was analyzed to characterize the malignant cell of origin. The sequences were obtained after amplification of bone marrow cDNA by using VH family-specific and CH primers, then compared with either directly sequenced patient germ-line or published VH gen sequences to assay for somatic mutation. Because somatic hypermutation of the VH gene occurs late in B cell development, its presence has been helpful in determining the cell of origin in other B cell malignancies. Overall, a median of 8.2% of the nucleotides had evidence of substitution within each VH gene sequence (range=2.7% to 16.5%), which is more prevalent than in any other reported tumor type. Strong evidence of prior antigenic selection pressure was also evident. The ratio of nucleotide substitutions that resulted in amino acid replacement was significantly higher in the complementarity-determining region than in the framework region (3.25 vs 1.56, respectively; p < 0.00005). No VH gene intraclonal diversity was noted, despite sequencing multiple clones (3-16) from each patient, nor was there evidence of further VH gene somatic mutation over the course of three patients' disease. These findings strongly imply that the malignant clone in MM evolves from a cell late in B cell development.

Myeloma Ig heavy chain V region sequences reveal prior antigenic selection and marked somatic mutation but no intraclonal diversity

The lg VH region sequence in 48 patients with multiple myeloma (MM) was analyzed to characterize the malignant cell of origin. The sequences were obtained after amplification of bone marrow cDNA by using VH family-specific and CH primers, then compared with either directly sequenced patient germ-line or published VH gen sequences to assay for somatic mutation. Because somatic hypermutation of the VH gene occurs late in B cell development, its presence has been helpful in determining the cell of origin in other B cell malignancies. Overall, a median of 8.2% of the nucleotides had evidence of substitution within each VH gene sequence (range=2.7% to 16.5%), which is more prevalent than in any other reported tumor type. Strong evidence of prior antigenic selection pressure was also evident. The ratio of nucleotide substitutions that resulted in amino acid replacement was significantly higher in the complementarity-determining region than in the framework region (3.25 vs 1.56, respectively; p &lt; 0.00005). No VH gene intraclonal diversity was noted, despite sequencing multiple clones (3-16) from each patient, nor was there evidence of further VH gene somatic mutation over the course of three patients' disease. These findings strongly imply that the malignant clone in MM evolves from a cell late in B cell development.

Adenoma-carcinoma sequence: a reappraisal with immunohistochemical expression of ferritin

To examine the biological significance of ferritin (FRN) expression, a retrospective immunohistochemical study was performed in normal colonic mucosae (n = 8), adenomas (n = 88), and colorectal carcinomas (n = 104). FRN was present in some epithelia in the crypt base of normal colonic mucosae. Significant cytoplasmic staining for FRN was revealed in 26 (29.5%) cases of adenoma and 54 cases (51.9%) of adenocarcinoma. The cancer cells had a higher proportion of FRN expression than those of adenomas or non-neoplastic mucosae (P < 0.001). Expression of FRN showed a positive association with the degree of dysplasia (P = 0.039) and the distal location of adenoma (P = 0.013). FRN expression tended to be associated with the tumor size (P = 0.083), but no substantial difference was observed among the histologic types of adenoma (P = 0.754). The results suggest that cytoplasmic FRN expression is associated with cellular proliferation. The proliferative index shows a significant difference through the adenoma-carcinoma sequence. Further investigation is necessary to clarify the clinical implication of FRN expression in tumor cells and normal-appearing mucosae.

Effect of cryopreservation on semen quality in patients with testicular cancer

OBJECTIVES

Current techniques in cryopreservation of human semen substantially decrease sperm quality. In addition, the pregnancy rate using cryopreserved sperm obtained from testicular cancer patients is lower than when sperm from normal fertile men is used. However, it is still unclear whether cryopreserved sperm from these patients is inherently defective or if the sperm loses its motility after thawing. This study was undertaken to assess the effect of cryopreservation on the quality and motion characteristics of semen from patients with testicular cancer before definitive therapy compared with semen from normal volunteers.

METHODS

We compared the sperm quality before and after cryopreservation in samples from 34 patients with testicular cancer and 30 normal volunteers who were referred for sperm banking over a 7-year period. The effects of cancer stage and histologic type on various semen parameters were also examined. A computer-assisted semen analysis was performed before and after cryopreservation on each specimen. The nitrogen vapor technique using Test yolk buffer with glycerol as a cryoprotective agent was used for cryopreservation. The motile sperm count and motion characteristics (motility, velocity, linearity, amplitude of the lateral head movement, motility index) were analyzed before and after cryopreservation and compared between the groups.

RESULTS

Semen quality did not significantly differ among patients with Stage I, II, or III cancer. However, semen quality tended to be poorer at higher cancer stages. In general, semen quality was better among patients with pure seminomas than with pure embryonal tumors; quality was worst among patients with mixed germ cell tumors. However, 71.4% of patients with mixed tumors presented with Stage III disease, whereas all patients with seminomas presented with Stage I disease. Significant differences were also seen in prefreeze motility (median, 42% [interquartile range, 24 to 51] versus 60.5% [range, 49 to 73]; P = 0.0004) and motile sperm count (6.7 x 10(6)/mL [range, 3.4 to 14.4] versus 50.0 [range, 24.6 to 72.0]; P = 0.0001) in patients compared with controls, respectively. The motile sperm count and percent motility significantly decreased in both patients and controls after cryopreservation (P = 0.0001). However, the percentage decline in motile sperm count and motion characteristics after cryopreservation did not differ significantly between patients and controls (P > 0.01).

CONCLUSIONS

We conclude that the effect of cryopreservation on sperm quality in patients with testicular cancer is identical to its effect on sperm from normal fertile men. Differences in values after preservation are explained by poor semen characteristics before freezing; semen quality declines with more extensive disease. Stage I patients also had poorer quality than control subjects. Thus, we recommend that routine sperm banking be encouraged among all patients with testicular cancer before the initiation of specific medical treatment. We also recommend that future efforts be focused on improving the technique of sperm banking.

Probing the mechanism of CRP activation by site-directed mutagenesis: the role of serine 128 in the allosteric pathway of cAMP receptor protein activation

Upon activation by cAMP, Escherichia coli cAMP receptor protein (CRP) controls the expression of a network of catabolite sensitive genes. The activation of CRP by cAMP involves conformational changes such as realignments between subunits and domains within the protein. To understand the molecular events that lead to the activation of CRP, point mutations at position 128 were introduced via site-directed mutagenesis in an attempt to specifically affect the subunit interfacial interactions, as well as the ligand-binding reaction. The biochemical and biophysical properties of these mutants were rigorously tested with the goal of identifying the partial reactions in the activation pathway that are perturbed by this specific mutation. Results from this study suggest that mutation of Ser 128 to Ala or Pro does not significantly disturb the overall secondary structure as monitored by circular dichroism. The energetics of subunit-subunit interaction and protein stability were monitored by sedimentation and spectroscopic techniques. Although these mutants were designed to interrupt intersubunit interactions, the energetics of subunit association and protein stability remain quantitatively the same as those of the wild-type CRP. Nevertheless, the ability of the subunit to be realigned to the DNA-binding form is significantly affected as reflected by the pronounced decrease in the susceptibility of mutant CRP to proteolytic digestion in the presence of cAMP. In addition, the binding affinity of cAMP to the first ligand site in mutants S128A and S128P is the same as that of the wild type, but the affinity to the second ligand site is reduced. This observation indicates that mutation at position 128 affects ligand binding by amplifying the magnitude of negative cooperativity. Mutation at residue 128 does not impair the ability of interdomain interactions as indicated by the quantitative response of a spectroscopic probe in the DNA-binding domain to the binding of cAMP to the ligand-binding domain. The S128A mutant binds to a specific DNA sequence about 50-fold weaker than the wild-type CRP, while the mutant S128P has no measurable DNA affinity under the same conditions. This observation is consistent with the in vivo result that both mutants display an inactive CRP phenotype (CRP-). In summary, these results suggest that communication between domains induced by cAMP binding can be dissociated from the proper subunit realignment of the CRP dimer that is crucial for the activation of CRP.(ABSTRACT TRUNCATED AT 400 WORDS)

Determination of microdialysis extraction fraction of cocaine by the no net flux method under high, low, and zero steady-state cocaine concentrations in rats

The effect of different steady-state cocaine concentration maintenance on the microdialysis extraction fraction of cocaine (in situ recovery; Ed) in the medial prefrontal cortex (mPFC) was examined. Male, adult Sprague-Dawley rats anesthetized with chloral hydrate were used. All rats were randomly divided into three groups and were given cocaine i.v. infusion of either 0.6 mg/kg/min (group A), 0.3 mg/kg/min (group B), or 0.0 mg/kg/min (group C). A steady-state cocaine concentration in the blood was obtained for both A and B groups. They were 24.3 +/- 2.3 microM, respectively. We then applied the no net flux microdialysis method to determine the Ed of cocaine in vivo for all three groups. Results revealed that there was no significant difference of Ed under these three different infusion regimens (group A: 16 +/- 2%; group B: 17 +/- 1%; group C: 21 +/- 2%). The steady-state cocaine concentration in the mPFC was also estimated to be 17.7 +/- 1.3 microM, 11.3 +/- 2.0 microM, and 0.7 +/- 0.6 microM, respectively. We then concluded that the Ed of cocaine in the mPFC is invariable while the steady-state cocaine concentration in the mPFC was ranging from 0 to 18 microM. This information is useful in the cocaine pharmacokinetic study since scientists are concerned about the variations of Ed while cocaine concentration in the mPFC is changing.

Self-association of Escherichia coli DNA-dependent RNA polymerase core enzyme

The extent of self-association of Escherichia coli DNA-dependent RNA polymerase core enzyme has been investigated by velocity sedimentation as a function of both NaCl and protein concentrations. The core enzyme, existing as essentially monomeric species having a sedimentation coefficient of 13.1 S at NaCl concentrations greater than 0.2 M, undergoes reversible self-association at lower salt concentrations. Estimates for the stoichiometry of association and equilibrium constants of reaction were determined from the effect of protein concentration on the weight-average sedimentation coefficient measured at different NaCl concentrations. Data analysis by a nonlinear curve-fitting procedure indicated that protein self-association is best described by a sequential model characterized by weaker association constants for each additional step of oligomerization, and any model that involves cooperative formation of oligomeric species can be excluded. These findings are at variance with the conclusion of a previous study [Shaner, S. L., Platt, D. M., Wensley, C. G., Yu, H., Burgess, R. R., & Record, M. T. (1982) Biochemistry 26, 5539-5551] which suggested that core RNA polymerase exists in equilibrium between monomeric and tetrameric forms of the enzyme and excluded the existence of intermediate species. Simulation of sedimentation velocity boundary and gradient profiles are used to assess the validity of both models of association of core protein. It was clear that had the core enzyme undergone a cooperative monomer<-->tetramer mode of association, then bimodality would have been observed in the derivative tracings of the sedimentation boundary under these experimental conditions. Nevertheless, no such observation was reported by Shaner et al. and this study. The sequential model favored by the results of this study is consistent with the proposed model resulted from a small-angle X-ray study [Heumann, H, Meisenberger O., & Pilz, I. (1982) FEBS Lett. 138, 273-276]. Further analysis of the data by the Wyman linked-function relationship [Wyman, J. (1964) Adv. Protein Chem. 19, 223-286] implies that core enzyme monomer loses approximately three counterions per contact upon association to higher oligomeric species.

Transplantation of CD34+ peripheral blood progenitor cells after high-dose chemotherapy for patients with advanced multiple myeloma

A major potential problem of autologous transplantation in the treatment of advanced malignancy is the infusion of tumor cells. A multi-institutional study of purified CD34-selected peripheral blood progenitor cell (PBPC) transplantation was conducted in 37 patients with advanced multiple myeloma receiving myeloablative chemotherapy. Fourteen days after intermediate-dose cyclophosphamide, prednisone, and granulocyte colony-stimulating factor (G-CSF), a median of 3 (range, 2 to 5) 10-L leukaphereses yielded 9.8 x 10(8)/kg (range, 3.7 to 28.3) mononuclear cells. The adsorbed (column-bound) fraction contained 5.9 x 10(6) cells/kg (range, 1.6 to 25.5) with 4.65 x 10(6) CD34 cells/kg (range, 1.2 to 23.3). Using Poisson distribution analysis of positive polymerase chain reactions with patient-specific complementarity-determining region 1 (CDR1) and CDR3 Ig-gene primers, tumor was detected in leukapheresis products from 8 to 14 unselected patients and ranged from 1.13 x 10(4) to 2.14 x 10(6) malignant cells/kg. After CD34 selection, residual tumor was detected in only three patients' products. Overall, a greater than 2.7- to 4.5-log reduction in contaminating multiple myeloma cells was achieved. CD34 PBPCs were infused 1 day after busulfan (14 mg/kg) and cyclophosphamide (120 mg/kg), and granulocyte-macrophage colony-stimulating factor was used until hematologic recovery. The median time to both neutrophil and platelet recovery was 12 days (range, 11 to 16 days and 9 to 52 days, respectively). The median number of erythrocyte and platelet transfusions was 7 (range, 2 to 37) and 3 (range, 0 to 85), respectively. Patients receiving fewer than 2 x 10(6) CD34 cells/kg had significantly prolonged neutropenia, thrombocytopenia, and an increased red blood cell and platelet transfusion requirement. Thus, CD34 selection of PBPCs markedly reduces tumor contamination in multiple myeloma and provides effective hematopoietic support for patients receiving myeloablative therapy.

Cryopreservation and semen quality in patients with Hodgkin's disease

BACKGROUND

Cryopreservation of semen from patients with Hodgkin's disease yields fewer motile sperm than from fertile men without Hodgkin's disease. However, although poor sperm quality and subfertility have been associated with Hodgkin's disease, whether the disease adversely affects sperm quality is not clear because many studies evaluated semen quality after chemotherapy or radiation therapy had begun. Furthermore, the effect of cryopreservation on semen quality in these patients is unknown. This study investigated pretreatment sperm quality and the effect of cryopreservation on semen quality in patients with Hodgkin's disease.

METHODS

Specimens from 39 patients with Hodgkin's disease and 30 normal volunteers who underwent sperm banking over a 5-year period were analyzed. No patient had undergone chemotherapy or radiation therapy before sperm banking. The nitrogen vapor technique, using Test-Yolk buffer with glycerol as a cryoprotective agent, was used for cryopreservation. Prefreeze and postthaw motile sperm count (MSC) and motion characteristics, namely motility, curvilinear velocity (VCL), linearity, amplitude of lateral head movement (ALH), and motility index, were compared between the two groups.

RESULTS

Prefreeze values for MSC (P = 0.0001), motility (P = 0.0001), motility index (P = 0.0001), and VCL (P = 0.0019) differed significantly between patients and donors. Except for linearity and ALH, postthaw sperm MSC, motility, VCL, and motility index decreased significantly (P = 0.0001) in both groups. However, the percentage decline in semen quality from prefreeze to postthaw values did not differ significantly between donors and patients.

CONCLUSION

The pretreatment semen quality in patients with Hodgkin's disease is poor compared with that of normal fertile men. However, half the patients had a normal MSC, so a clinical diagnosis of Hodgkin's disease does not predict cryopreservation outcome adequately. Semen cryopreservation should be encouraged as a routine part of the therapeutic management of men of reproductive age who will undergo chemotherapy or radiation therapy for Hodgkin's disease.

Activation of Ca(2+)-calmodulin-dependent protein kinase Ia is due to direct phosphorylation by its activator

Ca(2+)-Calmodulin-dependent protein kinase Ia (CaM kinase Ia) is phosphorylated, and its activity enhanced up to 50-fold, in the presence of a protein purified from pig brain termed CaM kinase Ia activator [Lee, J.C. and Edelman, A.M. (1994) J. Biol. Chem. 269, 2158-2164]. We report here that phosphorylation of CaM kinase Ia in the presence of the activator occurs primarily on threonine (87%) and slightly on serine (13%) residues. Treatment of CaM kinase Ia with the irreversible ATP affinity analogue, 5'-p-fluorosulfonylbenzoyl adenosine (FSBA), reduces its activity by 86% but has no effect on its ability to be phosphorylated, whereas FSBA-treatment of the activator reduces its ability to activate and phosphorylate CaM kinase Ia by 92 and 93%, respectively. Thus, CaM kinase Ia activator is a protein Thr/Ser kinase which activates by phosphorylating CaM kinase Ia rather than by enhancing the latter's autophosphorylation.

KR-25003, a potent analgesic capsaicinoid

The crystal structure of N-[3-(3,4-dimethylphenyl)propyl] (4-hydroxy-3-methoxyphenyl)acetamide, C20H25NO3, was determined to a final R value of 0.047. The vanilloid, amide and dimethylphenyl groups of the compound are nearly perpendicular with respect to one another. The overall conformation in the crystalline state is somewhat different from that of other capsaicinoids. The molecules are stabilized by intermolecular hydrogen bonds.

SB 203580 is a specific inhibitor of a MAP kinase homologue which is stimulated by cellular stresses and interleukin-1

A class of pyridinyl imidazoles inhibit the MAP kinase homologue, termed here reactivating kinase (RK) [Lee et al. (1994) Nature 372, 739-746]. We now show that one of these compounds (SB 203580) inhibits RK in vitro (IC50 = 0.6 microM), suppresses the activation of MAPKAP kinase-2 and prevents the phosphorylation of heat shock protein (HSP) 27 in response to interleukin-1, cellular stresses and bacterial endotoxin in vivo. These results establish that MAPKAP kinase-2 is a physiological RK substrate, and that HSP27 is phosphorylated by MAPKAP kinase-2 in vivo. The specificity of SB 203580 was indicated by its failure to inhibit 12 other protein kinases in vitro, and by its lack of effect on the activation of RK kinase and other MAP kinase cascades in vivo. We suggest that SB 203580 will be useful for identifying other physiological roles and targets of RK and MAPKAP kinase-2.

Increased expression of cell adhesion molecule P-selectin in active inflammatory bowel disease

The pathogenic changes of inflammatory bowel disease (IBD) depend on migration of circulating leucocytes into intestinal tissues. Although leucocyte rolling and tenuous adhesion are probably regulated by inducible selectins on vascular endothelia, little is known about the expression of these molecules in Crohn's disease and ulcerative colitis. Using immunohistochemistry on surgically resected specimens, this study investigated endothelial P-selectin (CD62, granular membrane protein-140) in frozen sections of histologically uninvolved tissues adjacent to inflammation (Crohn's disease = 10; ulcerative colitis = 10), from highly inflamed areas (Crohn's disease = 20; ulcerative colitis = 13), and from normal bowel (n = 20). By light microscopy, two forms of P-selectin immunoreactivity were detected that apparently corresponded ultrastructurally to stored and released distributions. Compared with the normal gut, there was a 3.7-fold increase of P-selectin immunoreactivity on veins (p < 0.0001), venules (p < 0.0001), and capillaries (p < 0.05) in the highly inflamed gut, without differences between Crohn's disease and ulcerative colitis. In the uninvolved gut, P-selectin expression was similar to that seen in normal controls, except for a focal increase of P-selectin in the vicinity of small lymphocyte aggregates. The dramatic upregulation of P-selectin in the inflamed tissue and its potential role in leucocyte trafficking support the concept of P-selectin blocking therapy for the control of active IBD.

Contributions of multiple basic amino acids in the C-terminal region of yeast ribosomal protein L1 to 5 S rRNA binding and 60 S ribosome stability

Previous studies suggest that the C-terminal region of ribosomal protein L1 from Saccharomyces cerevisiae is important for its interaction with the 5 S rRNA molecule. Within this region are several highly conserved basic amino acids including Lys276, Lys279, Lys289, Arg282, Arg285. To examine potential contributions of these amino acids to RNA-protein interaction and ribosomal assembly, effects of substitutions of these residues by methionine either individually or in combinations were examined. A methionine substitution of any one of the lysine residues did not significantly affect RNA binding in vitro. The mutant RNPs were as stable as the wild-type RNP. Yeast transformants expressing these mutant proteins grew at the same rate as the wild-type. However, mutant proteins containing substitutions of any two of these basic amino acids bound RNA weakly. The resultant RNPs were significantly less stable than the wild-type. Whereas cells expressing mutant L1 with a single substitution at 289 was not lethal, cells expressing mutant L1 with any double substitutions involving Lys289 as one of the substituted amino acids were lethal. These data suggest that Lys289 plays a key role in the binding of ribosomal protein L1 to 5 S rRNA. The other basic residues, particularly Arg282, and Arg285, in this region also contribute to RNA binding. These residues are predicted to locate on the same side of an alpha helix. We would like to propose a structural model for the yeast RNP that involves multiple contact sites located on one side of the helix in the C terminus of the protein and the 5 S rRNA. These basic amino acids also participate, directly or indirectly, in the interaction of the RNP complex with other components of the 60 S ribosomal subunit.

Antineutrophil antibodies in familial inflammatory bowel disease

BACKGROUND/AIMS

Antineutrophil cytoplasmic antibodies have been reported to occur more frequently in healthy first-degree relatives of patients with ulcerative colitis than in healthy controls. The aim of this study was to determine their prevalence in families in which more than one member was affected with inflammatory bowel disease.

METHODS

With use of an indirect immunofluorescence method, 168 affected members and 197 unaffected first-degree relatives in 56 such families were studied.

RESULTS

Antibodies were detected in 46% of patients with ulcerative colitis without a positive family history and in 44% of those within families with several affected members. There was no evidence of clustering of antibodies in particular families. Within families in which both ulcerative colitis and Crohn's disease coexisted, antibodies were detected primarily in patients with ulcerative colitis. Antibodies were seldom present (3%) in those patients with Crohn's disease, whether they were familial or nonfamilial cases. Similarly, antibodies were seldom present (3%) in controls or the unaffected first-degree relatives of patients with inflammatory bowel disease.

CONCLUSIONS

Antineutrophil cytoplasmic antibodies are associated with ulcerative colitis, and their presence is not increased in the first-degree relatives of patients with ulcerative colitis. They are more likely to be a consequence of the disease than a subclinical genetic disease marker.

Effect of cyclic phenyl saligenin phosphate and paraoxon treatment on vascular response to adrenergic and cholinergic agents in hens

The response of peripheral blood vessels to adrenergic and cholinergic agonists was examined 1, 3, 7, and 21 d after hens were treated with a single intramuscular injection of 2.5 mg/kg cyclic phenyl saligenin phosphate (PSP) or 0.10 mg/kg paraoxon (PXN). These two organophosphates (OPs) cause different clinical effects in exposed animals, as PSP causes organophosphate-induced delayed neuropathy (OPIDN) and PXN causes acute poisoning through inhibition of acetylcholinesterase. For these studies, the ischiadic artery was cannulated both prograde and retrograde and the blood was shunted through a pump to maintain a constant flow. Alterations in pressure measured at the pump outflow were used to indicate changes in limb vascular resistance. Dose-response curves were generated for the response to intravenous administration of acetylcholine (ACh), phenylephrine (PE), or salbutamol (SAL) (10(-8) to 10(-4) mol/kg). Acetylcholine at 10(-8) to 10(-7) mol/kg caused an increase in vascular resistance, whereas concentrations of 10(-5) to 10(-4) mol/kg caused a decrease in vascular resistance in hens given PSP 1 and 3 d previously. The response of PXN-treated hens to ACh was not significantly altered from that of vehicle-treated hens. The resistance generated in response to PE, an alpha 1-adrenergic agonist, in PSP-treated hens was greater than levels in vehicle-treated hens on d 1 and 3 and greater than the response seen in hens treated with PXN. Salbutamol, a beta 2-adrenergic agonist, at concentrations of 10(-7) to 10(-4) mol/kg caused an increase in resistance 1 and 3 d after PSP and a decrease on d 7. The responses to SAL were different in PXN-treated hens, as these hens demonstrated a lesser increase in resistance at concentrations of 10(-8) to 10(-7) mol/kg and a decrease in resistance at 10(-5) to 10(-4) mol/kg 1 d after administration of PXN. These observations indicate that response to vasoactive agents is altered in OP-treated hens and that responses differ between a compound capable of causing OPIDN (PSP) and a compound that only causes acute effects (PXN).

Antibodies to capsular polysaccharides are not protective against experimental Staphylococcus aureus endocarditis

The protective efficacy of antibodies to the Staphylococcus aureus capsular polysaccharide was examined in a rat model of catheter-induced endocarditis. Capsular antibodies were induced either by active immunization with killed S. aureus or by passive immunization with hyperimmune rabbit antiserum to S. aureus. Control rats were injected with phosphate-buffered saline or passively immunized with normal rabbit serum or rabbit antiserum to a nonencapsulated strain. Animals with indwelling catheters were challenged intravenously with 5 x 10(4) to 4 x 10(6) CFU of the homologous S. aureus strain (capsular serotype 5 strain Reynolds or serotype 1 strain SA1 mucoid). Both immunized and control rats developed S. aureus endocarditis. The numbers of S. aureus cells recovered from the blood and aortic valve vegetations of immunized rats were similar to those of control rats, indicating that capsule-specific antibodies were not protective. To determine whether the presence of an indwelling catheter interfered with antibody-mediated protection against S. aureus endocarditis, catheters were removed 2 h after insertion in additional groups of rats. An inoculum of 10(8) CFU of strain Reynolds was needed to provoke endocarditis in rats catheterized for 2 h, compared with 5 x 10(4) CFU for rats with indwelling catheters. Passively transferred capsular antibodies were not protective since both immunized and nonimmunized animals developed endocarditis, and quantitative cultures of blood and valvular vegetations revealed no differences between immunized and control animals. The findings of this study indicate that antibodies to the capsular polysaccharide are not protective in the rat model of experimental S. aureus endocarditis.