Search PubMed⌕ Search

Biomedical subjects

E Kessler

Publications and source records attributed to E Kessler.

At least 109 records · Page 6Linked to original sources
PubMed1978

Defective herpes simplex virus DNA: circular and circular-linear molecules resembling rolling circles.

The formation of defective herpes simplex virus (HSV) in BSC-1 cells and the synthesis of defective virus DNA was studied. The fourth consecutive passage of undiluted virus yielded defective DNA that was 0.008 g/ml more dense than wild type (w.t.) virus DNA. The amount of defective DNA increased at passage 6 concomitantly with the decrease in infectious virus progeny. The synthesis of defective DNA was always accompanied by w.t. virus DNA synthesis. Defective DNA from both infected nuclei and defective virions had a mol. wt. of 100 X 10(6) and was linear as determined by electron microscopy. Electron microscopy of defective virus DNA at passage 6 revealed circular molecules varying in size in addition to linear DNA molecules with the length of intact virion DNA. The circular DNA molecules had contour lengths of 10, 5, 2.5 and less than 2.5 micron. The smallest circular DNA molecules had a contour length of 0.3 micron, possibly one virus gene. In addition, circular-linear DNA molecules were observed in which both the circular and the linear components varied in length. Most of these DNA molecules had circular components of either 2.5 or 5.0 micron, and linear components varying in length from less than 1 to 50 micron. Based on the present study, it is proposed that the S component of w.t. virus DNA is fragmented into small circular molecules that serve as templates for DNA synthesis, possibly by the rolling circle mechanism.

Cell Line↗
PubMed1978

[Ultrastructural-morphometric analysis of polyenylphosphatidylcholine [PPC] treated cholestatic rat liver (author's transl)].

Essential phospholipid PPC was administered to male rats over 24 and 72 hours after operation on bile duct ligation. The subsequent alterations were studied by ultrastructural morphometry and correlated with serum enzyme changes. By the results evidence is accrued that hepatocellular mitochondria are prevented by phospholipid treatment to develop alterations as seen after bile duct ligation alone. This occurred although serum GLDH activity was significantly increased. The smooth endoplasmic reticulum exhibited a normotrophic behavior after PPC treatment of animals in which bile duct ligation was done. The surface of the rough membranes was found increased at hours 24 and 72 after bile duct ligation. The bile canaliculi were markedly dilated. However, this alteration was not accompanied by a marked loss of microvilli. Administration of the phospholipid induced a numerical increase of hepatocellular nuclei in both sham-operated and cholestatic animals independantly from the bile duct ligation. It is suggested by the results that the administration of the phospholipid PPC is of value in influencing the fine structural hepatic alterations as seen in cholestatis.

Alanine Transaminase↗
PubMed1977

Intramolecularly-quenched fluorescent peptides as fluorogenic substrates ofleucine aminopeptidase and inhibitors of clostridial aminopeptidase.

Fluorogenic oligopeptide derivatives of the type Lys(ABz)-ONBzl, where ABz iso-aminobenzoyl (anthraniloyl), X stands for Ala Phe, or Ala-Ala, and ONBzlis p-nitrobenzyloxy, were synthesized and shown to be hydrolyzed by leucine aminopeptidase. The hydrolysis is accompanied by an increase in fluorescence due to disruptionof the intramolecular quenching of the fluorescent anthraniloyl moiety by the nitrobenzyester group. The spectral characteristics of the compounds are not consistent withan energy transfer mechanism according to Förster, therefore the quenching isassumed to be caused by a direct encouter between the quenching and the fluorecentgroups. The change in fluorescence that accompanies the enzymic hydrolysis ofthe first peptide bound was used for quantitative measurement of the activity ofthe activity of leucine aminopeptidase and for the determination of some of itskinetic parameters. A bacterial aminopeptidase from Clostrdium histolyticumthat is very similar to leucine aminopeptidase in its substrate specificity inits substrate specificity did not hydrolyze the above peptidederivatives. Thehydrolysis of leucine p-nitroanilide by this enzyme was found to be inhibitedby the three peptides and the corresponding inhibition constants were determined.

Aminopeptidases↗
PubMed1977

Corneal rings with gram-negative bacteria.

Corneal rings have been described with corneal ulcerations caused by Gram-negative bacteria. Corneal rings were produced by intracorneal injections of viable Pseudomonas aeruginosa as well as heat-inactivated suspensions of Gram-negative bacteria (P aeruginosa and Escherichia coli) but not Gram-positive bacteria (Staphylococcus aureus) or Freund's adjuvant. It is suggested that endotoxin is the factor responsible for their production since purified endotoxin produced corneal rings after intracorneal injection. Histopathological examination of the areas corresponding to the corneal rings disclosed that the rings represented accumulations of polymorphonuclear leukocytes. Direct immunofluorescent studies of the corneal rings revealed staining for properdin and C3 complement but not for immunoglobulins. The present report suggests that endotoxin has the ability to stimulate the alternate pathway of complement through properdin activation with the production of chemotactic fragments that attract polymorphonuclear leukocytes into the cornea.

Animals↗
PubMed1977

The corneal response to Pseudomonas aeruginosa: histopathological and enzymatic characterization.

The host response to the intrastromal injection of heat-inactivated Pseudomonas aeruginosa cells was studied. An extensive polymorphonuclear leukocyte (PMN) infiltration, which progressed to ulceration within 1 week, was observed. In some cases descemetoceles also developed. Only a limited degree of PMN infiltration and no ulcerations were observed at 1 week in eyes treated with corticosteroids. Collagenase and proteolytic enzymes capable of degrading proteoglycans were found in the ulcerated corneas. A correlation was made between the level of these host-derived enzymes and the extent of corneal destruction. It was concluded that corneal destruction by P. aeruginosa depends not only on the Pseudomonas protease, which rapidly destroys the cornea, but also on host-derived enzymes which are capable of degrading both collagen and proteoglycans.

Animals↗
PubMed1977

Pseudomonas protease. Purification, partial characterization, and its effect on collagen, proteoglycan, and rabbit corneas.

The extracellular protease of a virulent strain of Pseudomonas aeruginosa was purified by DEAE-cellulose chromatography in two steps. SDS-polyacrylamide gel electrophoresis of the purified enzyme revealed a single band, and the enzyme was shown to be the major component of the bacterial filtrate. The protease was fully inhibited by Na2 EDTA, 1,10-orthophenanthroline, L-cysteine and Zn+2 ions but was insensitive to dissopropylphosphofluoridate. The elastase substrates orcein-elastin and acetyl-L-alanyl-L-alanyl-L-alamine-methyl ester were degraded by the enzyme. The protease activity toward soluble and insoluble collagen was found to be limited to the telopeptide region of the collagen molecule. With soluble collagen, conversion of the beta and gamma chains into monomeric alpha chains was observed. About 60% of the total proteoglycans and 1.5% of the total collagen were solubilized from rabbit corneas following incubation with the enzyme, and the solubilized products were nondialyzable. It was concluded that the purified protease has little or no collagenolytic activity and that dissolution of the cornea by Pseudomonas protease infection results essentially from the degradation of the protein backbone of the corneal proteoglycans.

Animals↗
PubMed1976

An extracellular aminopeptidase from Clostridium histolyticum.

An aminopeptidase was isolated from the culture filtrate of Clostridium histolyticum and purified to homogeneity. Absence of endopeptidase activity in the purified preparation was demonstrated. Gel filtration on a calibrated column indicates an apparent molecular weight of 340000 for the native enzyme. Gel electrophoresis of the denatured enzyme in the presence of dodecylsulfate in constant acrylamide concentration and in a concentration gradient, resulted in the appearance of a single component for which a molecular weight of 51000 and 59000 respectively, was calculated. From mobilities of crosslinked and denatured protein species a molecular weight of 56000 was obtained for the monomer. Specificity studies show that the enzyme cleaves all types of N-terminel amino acid residues including proline and hydroxyproline from small peptides and from polypeptides. The peptide bond formed between an N-terminal amino acid residue and proline is not cleaved by the enzyme. The combined action of aminopeptidase-P and clostridal aminopeptidase leads to complete hydrolysis of the proline-rich nonapeptide bradykinin. Low rates of hydrolysis was observed for charged residues, and amides of amino acids. Kinetic studies with five tripeptides of the general structure X-Gly-Gly, where X stands for Leu, Phe, Val, Ala, or Pro, show a decrease in Km with the increasing size of the hydrophobic side chain of X. The highest Kcat values are observed with proline and alanine. In the series Pro-Gly, Pro-Gly-Pro, Pro-Gly-Pro-Pro, the last peptide is the best substrate, indicating an active site complementary to at least four amino acid residues. The enzymatic activity is dependent on the presence of divalent cations, maximal activation being reached with Mn2+ and Co2+. The optimal pH for the Mn2+ and Co2+- activated enzyme is 8.6 and 8.2 respectively. The optimal temperature is 40 degrees C. Inhibition of the aminopeptidase was achieved with Zn2+, Cu2+ and p-mercuribenzoate, but not with diisopropylphosphofluoridate.

Amino Acids↗
PubMed1976

Effects of zinc sulfate on Pseudomonas aeruginosa infections and protease in rabbit corneas.

Zinc ions were shown to reversibly inhibit the activity of Pseudomonas protease. Zinc sulfate was more effective topically in preventing corneal perforations by this enzyme than either cysteine or edetate disodium (Na2 EDTA). The reversibility of the enzyme inactivation by zinc sulfate and its efficacy in preventing perforations were used to estimate the duration of the enzyme activity in the cornea. The protease was found to retain its activity in the rabbit cornea for up to two days after intrastromal injection. The extent of corneal destruction in rabbit corneas infected with live Pseudomonas cells was significantly greater in eyes treated with zinc sulfate than in controls, precluding its use in a clinical setting.

Animals↗
PubMed1976

Angioimmunoblastic lymphadenopathy: a case study.

The case of a 57-year-old man with lymphadenopathy fever, splenomegaly, and polyclonal gammopathy is described. The difficult clinical course, the short lived response to cytotoxic treatment, the frequent infections, the immunologic abnormality, and the histologic findings in lymph node biopsy and postmortem material justified our diagnosis of angioimmunoblastic lymphadenopathy with dysproteinemia, a new entity described recently.

Diagnosis, Differential↗
PubMed1976

Sinus histiocytosis with massive lymphadenopathy and spinal epidural involvement: a case report and review of the literature.

A case of "sinus histiocytosis with massive lymphoadenopathy" (SHML) in which spinal epidural involvement caused paraplegia is described. The literature pertaining to this newly recognized entity is reviewed; this review indicates that the process is not necessarily restricted to the lymph nodes and may be progressive in nature. The case we report is the first with histologically proved bone involvement.

Diagnosis, Differential↗