The role of cytochrome c4 in bacterial respiration. Cellular location and selective removal from membranes

The cellular location of cytochrome c4 in Pseudomonas stutzeri and Azotobacter vinelandii was investigated by the production of spheroplasts. Soluble cytochrome c4 was found to be located in the periplasm in both organisms. The remaining cytochrome c4 was membrane-bound. The orientation of this membrane-bound cytochrome c4 fraction was investigated by proteolysis of the cytochrome on intact spheroplasts. In P. stutzeri, 78% of the membrane-bound cytochrome c4 could be proteolysed, whilst 82% of the spheroplasts remained intact, suggesting that the membrane-bound cytochrome c4 is on the periplasmic face of the membrane in this organism. Cytochrome c4 was not susceptible to proteolysis on A. vinelandii spheroplasts, in spite of being digestible in the purified state. Cytochrome c5 was shown to have a similar cellular distribution to cytochrome c4. Selective removal of cytochrome c4 from membranes of P. stutzeri was accomplished by the use of sodium iodide and propan-2-ol, with the retention of most of the ascorbate-TMPD (NNN'N'-tetramethylbenzene-1,4-diamine) oxidase activity associated with the membrane. Sodium iodide removed most of the cytochrome c4 from A. vinelandii membranes with retention of 62% of the ascorbate-TMPD oxidase activity. Cytochrome c4 could be returned to the washed membranes, but with no recovery of this enzyme activity. We conclude that cytochrome c4 is not involved in the ascorbate-TMPD oxidase activity associated with the membranes of these two organisms.

Free and membrane-bound forms of bacterial cytochrome c4

Cytochrome c4 was isolated from cells of Pseudomonas aeruginosa, Pseudomonas stutzeri and Azotobacter vinelandii. The dihaem nature, Mr of approx. 20,000 and ferrohaem spectra in the region of the alpha- and beta-peaks define this family of cytochromes c. The behaviour of the holocytochromes in SDS was atypical, but removal of the haem groups resulted in a normal migration. In all three organisms most of the cytochrome c4 was tightly bound to the membrane, but some free cytochrome was detected. The membrane-attached cytochrome could be extracted with butanol, and this solubilized form was then indistinguishable in properties from the free form. Denitrifying rather than aerobic growth conditions hardly affected the total cytochrome c4 in the two pseudomonads, but there was slightly more free form and less membrane-attached form in denitrifying growth. The nature of the attachment of cytochrome c4 to the membrane is discussed and a model is proposed for the process of solubilization.

The efficacy results and safety profile of imipenem/cilastatin from the clinical research trials

Imipenem/cilastatin is highly effective for infections in many body sites against a broad range of gram-positive and gram-negative aerobic and anaerobic bacteria. During therapy, development of resistance is uncommon except in the case of Pseudomonas aeruginosa in which the incidence appears similar to that for other beta-lactam antibiotics. There appears to be a very low probability of cross-resistance. The clinical and laboratory adverse reactions are similar in type to those for other beta-lactam antibiotics. The frequency of colonization and superinfection during treatment with imipenem/cilastatin has been comparable to other antibiotics in comparative trials and to literature reports for other antibiotics for noncomparative trials.

Problems and benefits of an antibiotic compassionate therapy program

So-called compassionate therapy can provide life-saving drug(s) for patients but can also introduce liabilities that may discourage such treatment. The procedures required for compassionate use of imipenem/cilastatin and a summary of the results of its use are used as examples. Physicians requesting drugs for compassionate therapy face problems in the timely acquisition of antibiotic from the manufacturer and the completion of the regulatory and patient case report forms. The pharmaceutical company encounters difficulties with the return of documents, the ability to use the treatment data for registration claims, and the assessment of outcome and safety in patients with multiple confounding medical problems. The benefits of compassionate therapy for all participants should favor its continued use. Suggestions for the improvement of compassionate therapy programs include streamlining of case report forms and more disciplined completion of forms by investigators.

The safety profile of imipenem/cilastatin: worldwide clinical experience based on 3470 patients

The relative safety of imipenem/cilastatin for 3470 patients was reviewed to see if the safety profile was similar to that seen for the first 1723 patients treated. The most common clinical adverse experiences were local ones related to the site of intravenous infusion. Gastrointestinal adverse experiences included nausea, vomiting, or diarrhoea. The frequency of pseudomembranous colitis was low (0 X 1%). The most common central nervous system abnormality was seizure. The most common background factor was central nervous system abnormality including prior history of seizure. Dermatological adverse experiences included rash, pruritus and urticaria. Bleeding and decreased renal function were uncommon. The most common laboratory changes included transient increased liver function values, eosinophilia, positive Coombs' test (not associated with haemolysis) and increased platelets. The current clinical and laboratory safety data are similar to those obtained in the early part of the clinical trials.

Complexity in the redox titration of the dihaem cytochrome c4

Redox titration of the dihaem, two domain cytochromes c4 from Pseudomonas aeruginosa, Pseudomonas stutzeri and Azotobacter vinelandii showed complex behaviour indicative of the presence of two redox components. In the case of the P. stutzeri cytochrome c4, two spectroscopically distinct components were present during the redox titration. In contrast, cytochrome c-554(548) from a halophilic Paracoccus species is a stable dimer of a monohaem cytochrome which shows close homology to cytochrome c4, but does not show complexity in its redox titration. The presence of chemically distinct haem environments or anti-cooperative interactions between identical haem groups are two possible explanations for the redox complexity of cytochrome c4. The simple redox titration of cytochrome c-554(548) shows that haems situated relatively close together need not interact, but direct cleavage, separation and study of the domains will be necessary to decide whether they do or do not interact in the case of cytochrome c4.

Comparison of the sensitivity of the vaginal mucous membranes of the albino rabbit and laboratory rat to nonoxynol-9

Studies were conducted to compare the sensitivities of the vaginal mucous membranes of the albino rabbit and albino rat to irritation by the surfactant nonoxynol-9. The purpose of this comparison was to evaluate the rat as a model for screening vaginal products for their potential irritancy. Nonoxynol-9 at various concentrations in distilled water was administered intravaginally by lavage once a day for four consecutive days. On day 5, the animals were killed and the vaginal tissues were processed and examined histopathologically. Using a predetermined semiquantitative scoring system, it was found that the intensity of irritation was concentration dependent in both species. In the rabbit, the irritation was significantly greater than that in the rat, being mild with concentrations of 2.5 and 5% and moderate to severe at 12.5 and 25%. In the rat, irritation was negligible up to 12.5%, becoming mild at 25% and more moderate at 75%. Thus the vaginal mucosa of the rabbit is more sensitive than that of the rat and may be expected to give a more exaggerated representation of the irritation potential of a compound to the human vagina than would the rat mucosa.

Efficacy and safety of imipenem/cilastatin: a review of worldwide clinical experience

The clinical experience of 1,723 patients treated with imipenem/cilastatin in worldwide clinical trials is reviewed. Dosages of imipenem administered parenterally with cilastatin varied with the severity of the infection and included 250 mg four times a day; 500 mg three or four times a day, and 1 g three of four times a day. Infections of all body systems except the central nervous system due to gram-positive or gram-negative aerobes and anaerobes as well as those due to mixed organisms were treated. Clinical efficacy was demonstrated in 92% of infections. The adverse clinical and laboratory experiences associated with imipenem/cilastatin were similar to those of other beta-lactam agents and included disturbances of gastrointestinal and central nervous system function, allergic reactions, and transient elevations of liver enzyme levels.

Review of adverse experiences and tolerability in the first 2,516 patients treated with imipenem/cilastatin

The clinical and laboratory data relating to the adverse experiences and tolerability of imipenem/cilastatin in the first 2,516 patients treated with the antibiotic are reviewed, with special reference to the last 793. Clinical adverse experiences were predominantly related to the gastrointestinal system (nausea and vomiting), local injection site, and allergy (rash). A low frequency of drug-related seizures was also reported. The most frequent adverse laboratory experiences were transient elevations of liver function test values. In general, the safety profile was similar to that of other beta-lactam antibiotics.

Photochemical binding of photoallergens to human serum albumin: a simple in vitro method for screening potential photoallergens

A simple procedure employing UV spectroscopy is described for testing the ability of chemicals to form covalent conjugates with proteins after irradiation with the appropriate wavelength of light. A range of known photoallergens of widely differing structure has been tested using this procedure; results of these experiments, together with evidence from the scientific literature, provide a correlation between compounds known to be photoallergens and their ability to form covalent conjugates with proteins on irradiation with the appropriate wavelength of light. The method is proposed as an in vitro screening procedure for potential photoallergens.

Pleomorphism of Legionella pneumophila

Legionella pneumophila (Lp), serogroups 1-6, was grown in vitro on a variety of media, in embryonated hens' eggs, and in guinea pigs. The morphology of the microbe was examined by light, immunofluorescent, and electron microscopy (transmission, scanning, negative staining). The configuration of all serogroups examined differed somewhat on agar media, in liquid media, and in vivo. Each serogroup of Lp showed pleomorphic features indistinguishable from the others. Except for filamentous forms, pleomorphism was least conspicuous on agar. By contrast, pleomorphism was most apparent in yeast extract broth, and it was detected by all of the morphologic techniques employed. Bacilli were seen most commonly, but the spectrum of forms was as follows: cocci, coccobacilli (short bacilli), medium bacilli, bacilli with terminal cocci, filamentous forms, and branches. Diplococci, branches, and stalks were only rarely seen, and the latter form was never visualized by immunofluorescence. In tissue samples from infected guinea pigs and embryonated hens' eggs, Lp was typically a short bacillus, but coccoid and coccobacillary forms were seen. Lp is clearly a pleomorphic bacterium, particularly when grown in yeast extract broth. The variety of forms described herein might provide clues to taxonomy, ecologic niche, and physiology of Lp.

Safety and tolerance comparison of imipenem-cilastatin to cephalothin and cefazolin

Imipenem-cilastatin was compared, in two multicentre clinical trials, with cefazolin or cephalothin, in their efficacy, safety, and tolerance. Safety and tolerance for imipenem-cilastatin was similar to that of these two cephalosporins. There were more transient liver function test changes in the imipenem-cilastatin group, but the frequency was similar to that for beta-lactams in general. There were similar numbers of cases of transient neutropenia in each group. Clinical side effects were few for the treatment groups and all drugs were well tolerated.

Safety of cefoxitin: an approach to the analysis of laboratory data

The safety of cefoxitin, in terms of values obtained in laboratory tests during and after therapy, was estimated by three methods for analysis of data derived from controlled clinical comparisons of cephalothin and cefoxitin. Both antibiotics were found to be safe with respect to hematologic, renal, and hepatic function and did not differ significantly from each other. Laboratory data confirmed by tests performed serially and by paired related tests were analyzed by a novel method of comparison.

Multivariate Assessment of Phenetic Relationships Within the Tribe Luciliini (Diptera: Calliphoridae)

A multivariate assessment of phenetic relationships within the Luciliini was carried out. The canonical group means were derived from analysis of wing morphometric characters and assessed by considering the minimum spanning network superimposed on the three-dimensional ordination diagrams and by cluster analysis. Small subsets of taxa were analysed to clarify relationships within and between genera. Although there was some overlapping between species of Lucilia and Hemipyrellia, 4 basic groups emerged corresponding to the genera Dyscritomyia, Hypopygiopsis, Hemipyrellia and Lucilia. There was no support for Phaenicia and Francilia being accorded generic status. There was some doubt as to the synonymy of L. calviceps Bez. and L. papuensis Macq.

Wing Morphometrics of Australian Luciliini (Diptera: Calliphoridae)

Wing morphometrics of Australian representatives of the tribe Luciliini were examined in order to clarify phenetic relationships within the group. Wing variables were shown to be valid and consistent species characteristics. No significant variations were found due to sex, generation or locality. No clines could be detected from an analysis of 30 localities. Multiple species comparisons indicate that, at the 95% level of similarity, at least three groups apparently exist, corresponding to the genus Hemipyrellia and two groups within the genus Lucilia. There is no support for other genera, such as Phaenicia, as previously proposed. Some doubt exists as to the validity of placing fergusoni in the genus Hemipyrellia, as it appears from our data to be more similar to species of Lucilia.