Monoclonal antibodies to liver microsomal cytochrome P-450E of the marine fish Stenotomus chrysops (scup): cross reactivity with 3-methylcholanthrene induced rat cytochrome P-450

Hybridomas were prepared from myeloma cells and spleen cells of BALB/c female mice immunized with hepatic cytochrome P-450E purified from the marine fish, Stenotomus chrysops (scup). Nine independent hybrid clones produced MAbs, either IgG1, IgG2b, or IgM, that bound to purified cytochrome P-450E in radioimmunoassay. Antibodies from one clone MAb (1-12-3), also strongly recognized rat cytochrome P-450MC-B (P-450BNF-B; P-450c). The nine antibodies inhibited reconstituted aryl hydrocarbon hydroxylase (AHH) and ethoxycoumarin O-deethylase of scup cytochrome P-450E to varying degrees, and inhibited AHH activity of beta-naphthoflavone-induced scup liver microsomes in a pattern similar to that in reconstitutions, indicating that cytochrome P-450E is identical to the AHH catalyst induced in this fish by beta-naphthoflavone. MAb 1-12-3 also inhibited the reconstituted AHH activity of the major BNF-induced rat isozyme. Conversely, MAb 1-7-1 to rat cytochrome P-450MC-B had little effect on AHH activity of scup cytochrome P-450E, and did not recognize cytochrome P-450E in radioimmunoassay nor in an immunoblot. Scup cytochrome P-450E and rat cytochrome P-450MC-B thus have at least one common epitope recognized by MAb 1-12-3, but the epitope recognized by Mab 1-7-1 is absent or recognized with low affinity in cytochrome P-450E. The various assays indicate that the nine MAbs against cytochrome P-450E are directed to different epitopes of the molecule. These MAbs should be useful in determining phylogenetic relationships of the BNF- or MC-inducible isozymes and their regulation by other environmental factors.

Preparation and characterization of monoclonal antibodies to pregnenolone 16-alpha-carbonitrile inducible rat liver cytochrome P-450

Hybridomas were prepared from mouse myeloma cells and spleen cells derived from BALB/c female mice immunized with purified rat hepatic pregnenolone 16-alpha-carbonitrile (PCN) induced cytochrome P-450 2a/PCN-E. The monoclonal antibodies (MAbs) thus obtained were screened for binding to the purified P-450 2a/PCN-E by radioimmunoassay. Eleven independent hybrid clones produced MAbs, each of which was of a single mouse immunoglobulin subclass of the IgG1, IgG2a or IgG2b type. Each of the MAbs produced by the eleven individual hybrid clones bound strongly to P-450 2a/PCN-E as assessed by radioimmunoassay and immunoprecipitation of P-450 2a/PCN-E in Ouchterlony double-immunodiffusion plates. Of the eleven MAbs, three also bound strongly to the phenobarbital-inducible rat liver cytochrome P-450 PB-4. Thus, two classes of MAbs were obtained, one class specific for P-450 2a/PCN-E and a second class that bound to both PCN- and phenobarbital-inducible P-450 forms. The reactivities of one MAb from each class toward eight highly purified rat hepatic cytochromes P-450 were examined using solid phase enzyme-linked immunosorbent analyses. The MAb designated C2 was found to be specific for P-450 2a/PCN-E and did not cross-react with seven other P-450 forms. This MAb was shown to be an effective probe for monitoring, by Western blotting, the induction of microsomal P-450 2a/PCN-E by PCN and phenobarbital. The MAb designated C1 reacted both with P-450 2a/PCN-E and with the two major phenobarbital-inducible P-450 forms, PB-4 and PB-5. None of the MAbs was inhibitory towards P-450 2a/PCN-E-dependent aryl hydrocarbon hydroxylase, benzphetamine N-demethylase, ethoxycoumarin O-deethylase or ethymorphine N-demethylase activity, indicating that the epitopes recognized by these MAbs are not directly associated with catalytic activity. The strong reactivities of three of the MAbs with both P-450 2a/PCN-E and P-450s PB-4 and PB-5 indicate that these two structurally quite different cytochrome P-450 families share at least one common epitope. These new MAbs are additions to our library of MAbs to different cytochromes P-450 and should help further our understanding of the relationship of cytochrome P-450 phenotype and multiplicity to inter-individual differences in drug and carcinogen metabolism and sensitivity.

Experimental epiretinal proliferation induced by intravitreal red blood cells

We describe a reproducible animal model of epiretinal proliferation, based on intravitreal injection of red blood cells, that closely simulates the more benign proliferative extraretinopathies. Using light microscopy and scanning and transmission electron microscopy, we monitored the development and behavior of the experimental epiretinal membranes. We found breaks in the integrity of the retinal surface through which glial cells migrated onto the retina, proliferated into thick epiretinal tissue, and contracted to cause retinal pucker. All these steps were associated with the chronic inflammatory response to the long-lasting presence of red blood cells in the vitreous. Thus, the development of epiretinal membranes requires continuous intraocular stimulation in addition to a break in retinal integrity.

Newly-formed subretinal vessels. Fine structure and fluorescein leakage

The ultrastructure of experimentally induced newly formed subretinal vessels was correlated with the amount of fluorescein leakage demonstrated by the neovascular membranes during angiography. The membranes that demonstrated leakage contained subretinal vessels with a fenestrated endothelial wall and intermediate interendothelial cell junctions. As these subretinal plexi matured, they stopped demonstrating leakage. This involution process was accompanied by the formation of focal interendothelial tight junctions; however, loss of fenestrations was not observed. The membranes that never demonstrated fluorescein leakage also contained fenestrated subretinal vessels at both early and late stages of development; and their interendothelial junctions showed similar maturation from open to focal tight junctions. Thus all subretinal vessels had "leaky" morphology strongly resembling that of the normal choriocapillaris, whether they demonstrated fluorescein leakage or not. The authors conclude that newly formed subretinal vessels retain the characteristics of the choriocapillaris from which they are believed to proliferate; they have the potential to leak fluorescein at all stages of their development. The absence of fluorescein leakage during angiography cannot always be correlated with the absence of "leaky" morphology.

Retinal wound healing. Cellular activity at the vitreoretinal interface

Cellular activity at the vitreoretinal interface after full-thickness retinal wounds was studied in rabbit eyes, using light and electron microscopy. Glial cell extensions grew initially on the retinal surface around the wound site. This brief period of glial proliferation was associated with the posttraumatic inflammatory response and, more specifically, with phagocytic monocyte accumulation at the vitreoretinal interface. Once the inflammation subsided, this abortive attempt to grow membranes on the retinal surface stopped and true epiretinal membranes did not develop. Our observations suggest that intraocular inflammation and macrophage response determine the extent of healing and scarring on an injured retinal surface, and thus may play a key role in the pathogenesis of epiretinal membranes.

Experimental vitreous syneresis

Perfluoropropane gas was injected into the vitreous body of a primate eye. Clinical and morphologic studies revealed that the gas bubble created a large cavity within the vitreous. The cavity that subsequently filled with viscous liquid was completely enveloped by vitreous gel, thus simulating the clinical condition known as vitreous syneresis. The shell of residual vitreous, which was much thicker inferiorly and behind the lens than superiorly, seemed to be an intact and continuous layer. In spite of the extensive syneresis, posterior vitreous detachment failed to develop. Our findings suggest that a vitreous cavity, voluminous as it may be, is not sufficient to cause posterior vitreous detachment in the primate eye.

Insulin or increased concentration of zinc in liver, kidney or muscle does not alter the phosphoglucomutase activity in vivo

Injection of insulin into mice and rabbit has been reported to convert the latent form of phosphoglucomutase (E X Zn) to an active form (E X Mg) without any net increase in the protein associated with this enzyme (Hashimoto et al., Biochem. Biophys. Res. Commun., 27 (1967) 369 and Peck et al., J. Biol. Chem. 242 (1971) 1160). Because the injection of Cd in rats causes a 2-fold increase in Zn concentration in the liver, it appeared that such treatment in mice would increase the concentration of the latent enzyme and thereby enhance the insulin induced activation of the enzyme. The results however show that insulin or Cd treatment, alone or in combination do not alter the concentrations of the 2 forms of enzyme in liver, kidney or muscle of normal or fasted mice. In all instances the conversion of the latent enzyme to its activated form required preincubation with a chelating agent. Fractionation of the tissue homogenates showed that upon Cd injection the concentration of Zn in the fractions of Mr less and 1000 increased 6-fold in liver and 3-fold in kidney, that in muscle remained unchanged.

Disseminated talc granulomatosis. An unusual finding in a patient with acquired immunodeficiency syndrome and fatal cytomegalovirus infection

The association of disseminated magnesium silicate talc granulomatosis and acquired immunodeficiency syndrome is reported in a male homosexual who used intravenous drugs and who died of overwhelming cytomegalovirus (CMV) infection. Autopsy findings included widespread deposition of talc crystals in the lungs, liver, lymph nodes, bone marrow, and spleen. Typical CMV inclusions were seen in the lungs, kidneys, adrenal glands, gastrointestinal tract, and right eye. There was no evidence of malignancy. Analysis of peripheral blood neutrophil function revealed impaired chemotaxis and chemokinesis, but opsonophagocytosis had remained normal. The CMV infection in the small bowel was extensive and resulted in severe destruction of the muscularis propria and neural plexi, leading to marked dilatation and persistent diarrhea. The terminal course was marked by intractable hypotension, pneumonitis, and malnutrition, which could be attributed respectively to CMV involvement of the adrenal glands, lungs, and small bowel. The etiology and possible role of systemic talc granulomatosis in the development of immunosuppressive illness is reported herein.

Extensive endocardial mapping during sinus rhythm and ventricular tachycardia in a patient with arrhythmogenic right ventricular dysplasia

A 38 year old man with arrhythmogenic right ventricular dysplasia underwent electrophysiologic study with extensive endocardial mapping of the right ventricle. During sinus rhythm, markedly reduced amplitude with or without prolonged duration was noted in multiple electrograms of the right ventricle. Delayed activation of the right ventricular outflow tract electrogram was present. Two clinical types of ventricular tachycardia with a left bundle branch block configuration and either an inferior or a superior axis were induced by ventricular stimulation. Endocardial activation sequence during the tachycardias suggested that the tachycardia with an inferior axis originated near the infundibulum, while that with a superior axis originated near the midinferior area of the right ventricle. Both areas have been previously shown to be frequently impaired in right ventricular dysplasia.

Intravitreal expanding gas bubble. A morphologic study in the rabbit eye

The morphologic changes induced by an expanding bubble of perfluoropropane (C3F8) gas in the vitreous body have been studied in the rabbit eye by dissecting microscopy and scanning and transmission electron microscopy. Initial expansion of the gas displaces water from the vitreous; the remaining vitreous forms a compressed layer on the retinal surface. Subsequent absorption and contraction of the gas bubble is associated with gradual detachment of the compressed vitreous from the retina. Eventually, vitreous detachment is complete, except for residual attachments posteriorly to the medullary rays and anteriorly to the ciliary processes. The plane of vitreous separation is predominantly at the anatomic vitreoretinal junction, although scattered islands of outer cortical vitreous are found on the surface of the retina.

Diabetic neovascularization: permeability and ultrastructure

The permeability of newly formed blood vessels in proliferative diabetic retinopathy at different stages of development was correlated with their ultrastructural features. The young proliferating vessels were much more permeable to fluorescein than were the older vessels. Transmission electron microscopy revealed that the blood vessels within the young intravitreal proliferating fronds had intermediate interendothelial junctions, whereas the blood vessels within the old neovascular preretinal membranes had tight interendothelial junctions of the macula occludens type. Fenestrations were observed only rarely in the endothelial wall of either the young or the older proliferating vessels. We conclude that the principal route of fluorescein leakage from the newly formed blood vessels in proliferative diabetic retinopathy is via the interendothelial clefts.

Monoclonal antibodies to phenobarbital-induced rat liver cytochrome P-450

Somatic cell hybrids were made between mouse myeloma cells and spleen cells derived from BALB/c female mice immunized with purified phenobarbital-induced rat liver cytochrome P-450 (PB-P-450). Hybridomas were selected in HAT medium, and the monoclonal antibodies (MAbs) produced were screened for binding to the PB-P-450 by radioimmunoassay, for immunoprecipitation of the PB-P-450, and for inhibition of PB-P-450-catalyzed enzyme activity. In two experiments, MAbs of the IgM and IgG1 were produced that bound and, in certain cases, precipitated PB-P-450. None of these MAbs, however, inhibited the PB-P-450-dependent aryl hydrocarbon hydroxylase (AHH) activity. In two other experiments, MAbs to PB-P-450 were produced that bound, precipitated and, in several cases, strongly or completely inhibited the AHH and 7-ethoxycoumarin deethylase (ECD) activities PB-P-450. These MAbs showed no activity toward the purified 3-methylcholanthrene-induced cytochrome P-450 (MC-P-450), beta-naphthoflavone-induced cytochrome P-450 (BNF-P-450) or pregnenolone 16-alpha-carbonitrile-induced cytochrome P-450 (PCN-P-450) in respect to RIA determined binding, immunoprecipitation, or inhibition of AHH activity. One of the monoclonal antibodies, MAb 2-66-3, inhibited the AHH activity of liver microsomes from PB-treated rats by 43% but did not inhibit the AHH activity of liver microsomes from control, BNF-, or MC-treated rats. The MAb 2-66-3 also inhibited ECD in microsomes from PB-treated rats by 22%. The MAb 2-66-3 showed high cross-reactivity for binding, immuno-precipitation and inhibition of enzyme activity of PB-induced cytochrome P-450 from rabbit liver (PB-P-450LM2). Two other MAbs, 4-7-1 and 4-29-5, completely inhibited the AHH of the purified PB-P-450. MAbs to different cytochromes P-450 will be of extraordinary usefulness for a variety of studies including phenotyping of individuals, species, and tissues and for the genetic analysis of P-450s as well as for the direct assay, purification, and structure determination of various cytochromes P-450.

Comparative in vitro activities of teichomycin and vancomycin alone and in combination with rifampin and aminoglycosides against staphylococci and enterococci

The activity of teichomycin A2 was compared with that of vancomycin in vitro against clinical isolates of staphylococci and enterococci. Teichomycin A2 was more active than vancomycin active against all isolates tested. Synergistic studies also demonstrated that teichomycin A2 combined with rifampin is more active than vancomycin combined with rifampin against Staphylococcus aureus and Staphylococcus epidermidis isolates. Teichomycin A2, either singly or in combination with an aminoglycoside, was more active against Streptococcus faecalis isolates.

Clinical and microbiologic aspects of serious infections caused by Staphylococcus epidermidis

10 patients with serious infections caused by Staphylococcus epidermidis (8 cases of endocarditis in non-prosthetic valves, 1 was complicated by osteomyelitis, 1 case of osteomyelitis, and 1 case of septicemia) are described. Clinical and microbiologic features were evaluated including antibiotic sensitivity and synergy studies, phage typing and biotyping. Endocarditis tended to affect the elderly population and the clinical manifestations were quite similar to those caused by Streptococcus viridans. Both patients with osteomyelitis had involvement of the cervical spine with excellent response to antibiotic therapy. The only patient with septicemia acquired via hyperalimentation had delayed clearance of the bacteremia but ultimately responded to intravenous antibiotics. Rifampicin was the most effective of all antibiotics tested. All isolates were sensitive to penicillinase-resistant penicillins and cephalosporins and over half were sensitive to penicillin. Full synergistic activity was demonstrated with cephalothin and nafcillin in combination with rifampicin, and rifampicin-vancomycin was partially synergistic against the majority of the strains. Five of 8 available isolates were non-phage typeable and no definite pattern was established for various types of infections. Four of the 8 isolates were classified as biotype SIIa, 2 biotype SIIc and 2 biotype SVh.

A simplified method for cryopreservation of Plasmodium falciparum from continuous in vitro cultures

Human erythrocytes parasitized with Plasmodium falciparum, obtained from in vitro continuous cultures and stored at -185 degrees C and at -70 degrees C for several months, were successfully recovered. Ten per cent glycerol or 10% dimethyl sulphoxide in growth medium RPMI 1640 were used and found equally effective as cryopreservatives. This simplified method does not require centrifugation or special media before storage or after recovery of the parasites. The viability of the parasites is monitored in vitro by initiating new continuous cultures.

Experimental Staphylococcus epidermidis endocarditis in rabbit model

To study the natural course of catheter-induced endocarditis secondarily infected with Staphylococcus epidermidis, 29 rabbits had catheters introduced surgically through the carotid artery to the aortic valve. Forty-eight hours later the catheters were removed from five rabbits. The rabbits were inoculated intravenously with 10(8) colony-forming units of S epidermidis. Autopsies done at various intervals showed all rabbits with indwelling catheters had noticeable aortic valve vegetations with positive cultures for S epidermidis. In the group with catheters removed after 48 hours, less severe valvular lesions were noted. Metastatic seeding to kidneys, spleen, and liver were noted in both groups. Because of low cure rate in the treatment of S epidermidis endocarditis, this rabbit model could be used to study antibiotic regimens for valvular endocarditis.

Lidocaine toxicity from topical mucosal application. With a review of the clinical pharmacology of lidocaine

A case is reported of an infant who experienced seizures while being treated with a topical lidocaine 2% solution (Xylocaine 2% Viscous) for teething. The pharmacology of lidocaine is reviewed to alert physicians to the potential dangers of topical mucosal application of these preparations.