High-energy blunt pelvic ring injury incidence and polytrauma caseload in a single level I trauma center during COVID-19 related pseudo-lockdown measures: a retrospective cohort study based on a prospective registry

BACKGROUND

Pelvic ring injuries are potentially lethal lesions associated with polytrauma patients and need an efficient trauma team for their management. The purpose of this study was to evaluate the incidence of high-energy blunt pelvic ring injuries and the absolute number of polytrauma patients in a single level I trauma center during the 2020 pseudo-lockdown period related to the Coronavirus pandemic, and to compare it with corresponding periods in 2014-2019 in order to better understand the need of organized and dedicated personnel and infrastructures.

METHODS

This retrospective cohort study was based on data prospectively recorded into the institutional Severely Injured Patients' Registry. Data were obtained for each year period (January 1st to December 31st) and corresponding pseudo-lockdown period (March 16th to June 19th). High-energy blunt pelvic ring injuries inclusion criteria were: (1) Registry entry between January 1st, 2014 and December 31st, 2020; (2) age ≥ 16 years old; and (3) pelvic ring injury presence. Corresponding exclusion criteria were: (1) death before admission; (2) transfer from another institution > 24 h after trauma; (3) penetrating, blast, burn and electrical injuries, drownings; (4) patients living outside the defined institution's catchment area; and (5) any document attesting the patient's will to not participate in any study. Polytrauma patients inclusion criteria were: (1) Registry entry between January 1st, 2014 and December 31st, 2020; (2) age ≥ 16 years old; and (3) Injury Severity Score ≥ 16. Corresponding exclusion criteria were: (1) death before admission; (2) transfer from another institution > 24 h after trauma; and (3) any document attesting the patient's will to not participate in any study. Categorical variables were reported using proportions and continuous variables using medians and interquartile ranges. Because data were exhaustive for the authors' level I trauma center, no inferential statistics were computed.

RESULTS

The incidence of high-energy blunt pelvic ring injuries and the absolute number of polytrauma patients remained within range of previous years despite pseudo-lockdown measures.

CONCLUSIONS

These observations bring better knowledge about pseudo-lockdown's impact on trauma and may help for future health strategy planning by pointing out the importance of maintaining the activity of level I trauma centers in terms of personnel and infrastructures.

Management of high-energy blunt pelvic ring injuries: A retrospective cohort study evaluating an institutional protocol

INTRODUCTION

High-energy blunt pelvic ring injuries with hemodynamic instability are complicated by a high mortality rate (up to 32%). There is no consensus on the best management strategy for these injuries. The aim of this study was to evaluate the high-energy blunt pelvic ring injury management protocol implemented in the authors' institution.

PATIENTS AND METHODS

This retrospective cohort study was performed in an academic level I trauma center. The institutional protocol incorporates urgent pelvic mechanical stabilization of hemodynamically unstable patients not responding to a pelvic belt, fluids, and transfusions. If hemodynamic instability persists, angiography ± embolization is performed. Adult patients sustaining a high-energy blunt pelvic ring injury between 2014.01.01 and 2019.12.31 were included in the study. The primary outcome was mortality at 1, 2, 30 and 60 days. The secondary outcomes were the number of packed red blood cell units transfused during the first 24 h, intensive care unit stay, and total hospitalization length of stay.

RESULTS

192 high-energy blunt pelvic ring injury patients were analyzed. Of these, 71 (37%) were hemodynamically unstable, and 121 (63%) were stable. The overall in-hospital mortality of the hemodynamically unstable and stable groups was 20/71 (28.2%) and 4/121 (3.3%) respectively (p<0.001). Cumulative mortality rates for hemodynamically unstable patients were 15.5% at day 1, 16.9% at day 2, 26.8% at day 30 and 28.2% at day 60, and for hemodynamically stable patients, rates were 0% at day 1 and 2, 2.5% at day 30 and 3.3% at day 60. Unstable patients required a higher number of packed red blood cell units than stable patients during the first 24 h (5.1 vs. 0.1; p<0.001). Intensive care unit length of stay and total hospitalization duration was 11.25 and 37.4 days for unstable patients and 1.9 and 20.9 days for stable patients (p<0.001).

CONCLUSIONS

For both hemodynamically unstable and stable patients, the institutional protocol showed favorable mortality rates when compared to available literature. Comparative studies are needed to determine the management strategies with the best clinical outcome and survival.

[Management of ankle osteoarthritis in the young adult]

Ankle osteoarthritis often presents in patients with a history of lower leg trauma. Hence, they are young with sportive demands and in the active labor phase, treatment must be adapted. Non-surgical treatment is based on corrective orthotics, supportive shoes, and intraarticular hyaluronic acid injections. Joint preserving surgery (JPS) represents a valid alternative to the traditional ankle fusion. JPS may restore normal biomechanics of the ankle joint, resulting in substantial postoperative pain relief, functional improvement, and slowing of the degeneration process. Overall, JPS defers the need for secondary surgeries in most of these young patients, making these patients suitable candidates for joint motion-preserving surgery, as is the case of ankle arthroplasty.

The Intraseptal Course of the Superficial Peroneal Nerve: An Anatomic Study

BACKGROUND

Anatomic and clinical studies show many variants of the superficial peroneal nerve (SPN) course and branching within the compartments and at the suprafascial layer. The anatomy of the transition zone from the compartment to the subcutaneous layer has been occasionally described in the literature, mainly in studies reporting the intraseptal SPN variant in 6.6% to 13.6% of patients affected by the SPN entrapment syndrome. Despite the little evidence available, the knowledge of the transition zone is relevant to avoid iatrogenic lesions to the SPN during fasciotomy, open approaches to the leg and ankle, and SPN decompression. Our anatomic study aimed to describe the SPN transition site and to evaluate the occurrence of a peroneal tunnel and of an intraseptal SPN variant.

METHODS

According to the institutional ethics committee requirements, 15 fresh-frozen lower limbs were dissected to study the SPN course and its branching, focusing on the transition site to the suprafascial layer.

RESULTS

The SPN was located in the anterior compartment in 2 cases and in the lateral in 13. An intraseptal tunnel was present in 10 legs (66%), at a mean distance of 10.67 cm from the lateral malleolus. Its mean length was 2.63 cm. The tunnel allowed the passage of the main SPN in 8 cases and of its branches in two. In the remaining 5 legs (33%), the SPN pierced a crural fascia window.

CONCLUSION

In our sample a higher rate than expected of intraseptal SPN variants was found.

CLINICAL RELEVANCE

The knowledge of the anatomy of the SPN course and intraseptal variant is relevant to avoid iatrogenic lesions during operative dissection. Further studies are needed to evaluate the effective prevalence of an intraseptal tunnel, independently from the SPN entrapment syndrome, and how to avoid associated iatrogenic complications.

Is vitamin D deficiency a risk factor for osteonecrosis of the jaw in patients with cancer? A matched case-control study

PURPOSE

A previous case-control histomorphometric study showed higher odds of osteomalacia in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Vitamin D deficiency causes osteomalacia and may therefore be involved in the pathogenesis of BRONJ. The present case-control study aimed at testing such hypothesis.

MATERIALS AND METHODS

BRONJ+ and BRONJ- patients treated with bisphosphonates were matched by sex (same) and age (within 5 years). Serum 25-hydroxy-vitamin D (25-OH-D), parathyroid hormone, bone alkaline phosphatase, total procollagen type 1 amino-terminal propeptide, carboxy-terminal collagen crosslinks, Dickkopf WNT signaling pathway inhibitor 1 and sclerostin were measured.

RESULTS

The main outcome was vitamin D deficiency defined as 25-OH-D < 50 nmol/l. A total of 51 BRONJ+ and 73 BRONJ- patients were studied. The frequency (95% CI) of vitamin D deficiency was 59% (45%-72%) in BRONJ+ and 62% (48%-75%) in BRONJ- patients. This amounts to a difference of -3% (-22%-16%, p = 0.77) for BRONJ+ patients. Serum 25-hydroxy-vitamin D and parathyroid hormone were similar in BRONJ+ and BRONJ- patients. Among the bone metabolism markers, only sclerostin differed between the two groups, being higher in BRONJ+ patients.

CONCLUSION

The present matched case-control study suggests that vitamin D deficiency is not a risk factor for BRONJ.

Treatment of Morton's neuroma: A systematic review

BACKGROUND

The treatment of Morton's neuroma (MN) can be operative, conservative and infiltrative. Our aim was the evaluation of evidence on outcomes with different types of conservative, infiltrative and surgical treatment in patients affected by primary MN.

METHODS

The bibliographic search was conducted in MEDLINE, Cochrane Library, DARE. Only studies in English were collected. The last search was in August 2015. Case series and randomized controlled trials (RCTs) assessing patients' satisfaction or pain improvement at an average follow-up of at least 6 months after treatment of primary MN were included. Two reviewers selected the studies, evaluated their methodological quality, and retrieved data independently.

RESULTS

Of 283 titles found, only 29 met the inclusion criteria. Data showed better outcomes with operative treatment.

CONCLUSIONS

The evaluated case series and few RCTs showed better results with invasive treatment. More and better RCTs which evaluate risk-benefit ratio are required to confirm these results.

Zancolli Technique for Delayed Repair of Tibialis Anterior Tendon Rupture: A Case Report and Literature Review

BACKGROUND

Several techniques for repair of tibialis anterior tendon ruptures (TATRs) are reported, although it is a rare lesion. We describe a case of TATR, discuss our treatment, and review the criteria for the choice of treatment.

METHODS

In November 2015, a 61-year-old woman presented to our department 13 days after an injury to her left ankle, with avulsion of TAT. Because of the stump retraction, we performed a Zancolli-like plasty, anchoring the tendon to the navicular bone. Evidence about the timing and type of surgery has been reviewed.

RESULTS

The patient was followed up for 16 months before being discharged. The American Orthopaedic Foot and Ankle Society score improved from an initial value of 32 to a final score of 90.

CONCLUSIONS

The choice of treatment depends on several factors. Patients' physical demands and the type of rupture guide the choice of surgical technique.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Retrospective.

Molecular typing of erythromycin-resistant streptococcus pyogenes strains with the M phenotype isolated in Italy

To assess the spread of the new M phenotype, various erythromycin-resistant Streptococcus pyogenes strains from three Italian cities (Verona, Monza, Florence) were characterised. Each strain was analysed for the presence of genes ermAM and mefA, for the ability to accumulate radioactive erythromycin in the absence of sodium arsenate, for the protein T serological type, and for the DNA macrorestriction profile identified by means of pulsed-field gel electrophoresis. In a number of strains, the presence of the inducible ermAM gene was demonstrated; all these strains were negative in the efflux-pump detection assay, did not possess the mefA gene, and had similar restriction profiles. The strains with the efflux mechanism and mefA gene belonged to different serotypes. Of these, only one serotype, T4, was isolated in all three cities. The restriction profile analysis with SmaI and SfiI revealed a very close correlation between strains with the same serotype.

Comparative affinities for penicillin-binding proteins of multipolar ionic amphoteric cephalosporins in gram-negative bacteria

Chemical modification of the highly reactive 7-aminocephalosporanic acid has yielded many compounds with improved activities and expanded clinical spectra. Introduction of an alpha-oxyimino group in C-7 position has given rise to improved activity against Gram-negative bacteria as a consequence of the high affinity of compounds carrying this substituent for the essential penicillin-binding protein (PBP) 3. The spectrum of activity of oxyimino cephalosporins has been further expanded by introduction of substituents with a quaternary nitrogen in C-3 position. These compounds have maintained their high affinity for the essential PBP 3, typical of the third generation cephalosporins and have acquired an improved ability to cross the outer membranes of Gram-negative bacteria. Among these compounds cefepime also exhibits high affinity for PBP 2, a very unusual property among cephalosporins.

Lysozyme inhibitors enhance immune response in mice

The effect of hen egg-white lysozyme (HEWL) inhibitors (such as heparin, histidine methylester, chitotriose, chitobiose) on immune response was evaluated by measuring antibody-producing cells and circulating antibodies in mice inoculated with these substances and the test antigen (SRBC or BSA). It was found that these compounds have an immuno-enhancing effect which is directly proportional to their inhibitory activity on HEWL. Conversely, HEWL inhibited the immunoenhancing effect of these compounds when injected together with these and the test antigen. The results suggest that one possible mechanism by which adjuvants stimulate immune response may be the inhibition of endogenous lysozyme.

Modulatory effects of hen egg-white lysozyme on immune response in mice

The effect of her egg-white lysozyme (HEWL) on immune response was evaluated by measuring antibody-producing cells and circulating antibodies in mice inoculated with the test antigen (SRBC or BSA) and HEWL at the same time but in a separate body area. HEWL caused a premature decline in SRBC-specific plaque forming cells (PFC) and a reduction in the total amount of these cells. HEWL inhibited antibody production against BSA in the primary response, but was devoid of any effect on the secondary response elicited in the same mice by a second inoculation of the test antigen. The inhibitory effect of HEWL was dose-dependent, being maximal with 300 micrograms, required an enzymatically active protein and was not shown by other basic proteins. HEWL also abolished the enhancing effect of LPS and CFA on anti-BSA antibody production. The inhibitory activity of HEWL was further increased by hydrolyzed peptidoglycan. These results suggest that HEWL modulates the immune response in mice and performs this function through activation of non-specific suppression mechanisms.

Structure-activity relationship of new 2-substituted penem antibiotics

The antibacterial activities of three new penems with 4-hydroxyprolinamide, 1-prolinamide and N-methyl-N-2-propionamide substituents, respectively, in position 2 and of their stereoisomers were examined against Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Escherichia coli and Pseudomonas aeruginosa. All substitutes conferred a broad antibacterial spectrum on the penem moiety. Changes in stereoisomerism selectively improved the activity against E. coli, S. aureus or enterococci. The structure-activity relationships of each compound were discussed in relation to minimum inhibitory concentrations, penicillin-binding protein (PBP) affinity and outer membrane permeability coefficient in E. coli. In this microorganism, PBP 2 was the target for all compounds. Changes in stereoisomerism influenced the affinity for PBPs 1A/B and 2. All antibiotics easily permeated the outer membrane of E. coli and, within each group of compounds, the penetration rate correlated with the antibacterial activity.

Target for bacteriostatic and bactericidal activities of beta-lactam antibiotics against Escherichia coli resides in different penicillin-binding proteins

The relationship between cell-killing kinetics and penicillin-binding protein (PBP) saturation has been evaluated in the permeability mutant Escherichia coli DC2 in which the antimicrobial activity of beta-lactams has been described as being directly related to the extent of saturation of the PBP target(s). Saturation of a single PBP by cefsulodin (PBP 1s), mecillinam (PBP 2), and aztreonam (PBP 3) resulted in a slow rate of killing (2.5-, 1.5-, and 0.8-log-unit decreases in the number of CFU per milliliter, respectively, in 6 h). Saturation of two of the three essential PBPs resulted in a marked increase in the rate of killing, which reached the maximum value when PBPs 1s and 2 were simultaneously saturated by a combination of cefsulodin and mecillinam (4.7-log-unit decrease in the number of CFU per milliliter in 6 h). Inactivation of all three essential PBPs by the combination of cefsulodin, mecillinam, and aztreonam further increased the killing kinetics (5.5-log-unit decrease in the number of CFU per milliliter), and this was not significantly changed upon additional saturation of the nonessential PBPs 5 and 6 by cefoxitin. Similar relationships between PBP saturation and killing kinetics were obtained with imipenem and meropenem at concentrations which inhibited only one PBP (PBP 2), only two PBPs (PBP 1s and 2), or all three essential PBPs. Saturation of one or more PBPs also resulted in a different rate of bacteriolysis, the highest rate being obtained by the cefsulodin-mecillinam combination and by 5 micrograms of either imipenem or meropenem per ml. All of these conditions caused saturation of PBP 2 and saturation or extensive binding of PBP 1s. However, none of these conditions caused determined the fastest possible rate of killing, which occurred only when all three essential PBPs were saturated. It was concluded that the actual killing effect of beta-lactams is reflected by killing rates that approach the fastest possible rate for the given microorganism and that the targets for the bactericidal activity are precisely those PBPs whose saturation or binding occurs under conditions.

Quinolone binding to DNA is mediated by magnesium ions

The binding of plasmid DNA to norfloxacin, a quinolone antibacterial agent, was investigated by fluorescence, electrophoretic DNA unwinding, and affinity chromatography techniques. The amount of quinolone bound to DNA was modulated by the concentration of Mg2+. No interaction was evident in the absence of Mg2+ or in the presence of an excess of Mg2+, whereas maximum binding was observed at a Mg2+ concentration of 1-2 mM. The experimental data can be fitted to the formation of three types of Mg adducts: a binary adduct with norfloxacin and Mg2+, a binary adduct with DNA and Mg2+, and a ternary adduct with quinolone, plasmid, and Mg2+. We propose a model for the ternary complex, in which Mg acts as a bridge between the phosphate groups of the nucleic acid and the carbonyl and carboxyl moieties of norfloxacin. Additional stabilization may arise from stacking interactions between the condensed rings of the drug and DNA bases (especially guanine and adenine), which may account for the preference exhibited by quinolones for single-stranded and purine-rich regions of nucleic acids. Other possible biochemical pathways of drug action are suggested by the observation that norfloxacin binds Mg2+ under conditions that are close to physiological.

Staphylococcal endo-beta-N-acetylglucosaminidase inhibits response of human lymphocytes to mitogens and interferes with production of antibodies in mice

The effect of a bacteriolytic enzyme, the endo-beta-N-acetylglucosaminidase excreted by Staphylococcus aureus (SaG) on the response of human lymphocytes to mitogens and on the immune response in mice has been studied. SaG inhibited incorporation of [3H]thymidine into TCA-precipitable material by human peripheral lymphocytes stimulated either by phytohemagglutinin or by concanavalin A, as well as formation of cytoplasmic immunoglobulin-containing cells by B lymphocytes treated with pokeweed mitogen. In all cases the level of inhibition first increased with the SaG concentrations reaching values of over 80% at an enzyme concentration of 100 micrograms/ml, and then decreased. Heat-inactivated SaG as well as SaG treated with both polyclonal and monoclonal specific antibodies or enzyme inhibitors such as chitotriose or hydrolyzed peptidoglycan had no effect on lymphocyte response to mitogens. In mice, SaG at a dose of 300 micrograms per mouse was found to cause a fourfold decrease in the anti-BSA antibody titer and an approximately 70-75% reduction in the immunoglobulin-containing cells in the spleens of mice injected with sheep red blood cells. SaG also completely abolished the enhancing effect of adjuvants such as muramyldipeptide, Freund's complete adjuvant, and Escherichia coli lipopolysaccharide. When SaG was injected into mice together with S. aureus peptidoglycan hydrolyzed either by SaG or by human lysozyme, the inhibitory effect on both production of anti-BSA circulating antibodies and appearance of Igc cells in the spleens of mice injected with sheep red blood cells was enhanced. As we know that (a) human tissues contain endo-beta-N-acetylglucosaminidases; (b) other human hexosaminidases (lysozymes) have previously been shown to interfere with the functions of immunocompetent cells; and (c) products of hexosaminidase hydrolysis of peptidoglycan (muropeptides) known to modulate immune response are ordinarily found in the urine of healthy persons, the possibility that hexosaminidases play a major role in the regulation of the immune response is raised and discussed.

Relevance of ionic effects on norfloxacin uptake by Escherichia coli

The uptake of the quinolone drug norfloxacin by Escherichia coli was investigated at initial rate kinetics at different pH and monovalent/divalent metal ion concentration. The results support a simple diffusion mechanism for quinolone incorporation into cells. The uptake process decreases under acidic conditions. The presence of Na+ or K+ ions does not affect the results to an appreciable extent, whereas divalent ions cause a dramatic decrease in drug incorporation. The antibacterial activity, evaluated under identical experimental conditions, shows a direct relationship with the uptake data. As a general explanation for the above results it is suggested that the ability of the drug to penetrate into cells is a function of its net charge. The molecule in the zwitterionic form exhibits maximum permeation properties, whereas the uptake is remarkably reduced when the drug bears a net charge as a result of ionization or complex formation with bivalent ions. These results allow further insight into the mechanism of quinolone access to the intracellular compartment.

The effect of the minor groove binding agent DAPI (4,6-diamidino-2-phenyl-indole) on DNA-directed enzymes: an attempt to explain inhibition of plasmid expression in Escherichia coli [corrected]

The activity of DAPI, on a number of DNA-directed enzymes involved in DNA topology, transcription, replication and repair, is reported in this paper. DAPI was always more inhibitory than ethidium bromide, in particular against RNA polymerase and DNA ligase, which seemed to be specifically affected. While the effect on RNA polymerase is likely due to a preferential occupancy of the promoter region, that on DNA ligase could rely upon a mechanism of steric hindrance in the minor groove. These phenomena, independently from an alteration of the tertiary structure of DNA by the ligand, can account for the previously reported inhibition of plasmid expression in Escherichia coli.

Mechanisms of macrolide resistance in Ureaplasma urealyticum: a study on collection and clinical strains

Ureaplasma urealyticum is considered as a species which is intrinsically sensitive to macrolides (MIC less than 1 microgram/ml). Nevertheless, some of the strains recently isolated in our laboratories showed moderate to high levels of resistance (MICs ranging from 2 micrograms/ml to 100 micrograms/ml). In particular, a strain (CT28) isolated from a patient with nongonococcal urethritis long treated with erythromycin revealed a MIC greater than 100 micrograms/ml for this antibiotic. In order to investigate the mechanisms of resistance, strain CT28 and ten clinical and laboratory U. urealyticum strains were compared for the sensitivity to six antibiotics including three macrolides. Moreover the amount of macrolide uptake and the specific antibiotic binding to ribosomes were studied. Strain CT28 was resistant to josamycin, erythromycin, roxithromycin, lincomycin and clindamycin but sensitive to minocycline. When compared to a sensitive strain, strain CT28 showed a six-fold reduction in intracellular macrolide influx and accumulation and a reduction in antibiotic binding to ribosomes. The mechanisms implicated in these differences may be important for macrolide resistance in U. urealyticum.

Lysozyme-induced inhibition of the lymphocyte response to mitogenic lectins

Both human lysozyme (HL) and hen egg white lysozyme (HEWL) inhibited the proliferative response of peripheral blood lymphocytes to T cell mitogens such as the lectins phytohemagglutinin and concanavalin A. This inhibition was observed both when HL or HEWL was added to the lymphocyte cultures in combination with phytohemagglutinin or concanavalin A and when lymphocytes were pretreated with either lysozyme and extensively washed prior to culture with mitogens. Under both conditions, the effects were strictly dose dependent; the lysozyme concentrations yielding maximal inhibitory effect were 5 micrograms/ml for HL and 1 microgram/ml for HEWL, while both lower and higher concentrations were less effective. Specific antilysozyme rabbit sera completely prevented the inhibitory effects of both HL and HEWL on the proliferative response of lymphocytes to phytohemagglutin or concanavalin A. Chitotriose (a lysozyme inhibitor) caused a strong reduction in the inhibitory effects of the two lysozymes on the lymphocyte response to either lectin. HL and HEWL also were found to markedly inhibit the polyclonal B cell proliferation and differentiation induced by pokeweed mitogen and T cells. A less marked inhibition was also obtained when T cells, but not B cells, were pretreated with HL or HEWL. Again, as in the experiments with T cell mitogens, the effects were dose dependent and 5 micrograms/ml HL and 1 microgram/ml HEWL proved to be the most effective concentrations. The possible mechanisms by which lysozyme inhibits the lymphocyte response to mitogenic lectins are considered and discussed. The enzymatic activity seemed to perform an essential function, as shown by the loss of effect when the heat- or trypsin-inactivated lysozymes were used and by the fact that only the enzymatically active compound, among certain semisynthetic derivatives of HEWL, inhibited the lymphocyte response to the mitogens. However, the cationic properties of the lysozyme molecule appeared to be essential too, since enzymes with a similar specificity of action showed effects similar to those observed with HL or HEWL only when they carried a strong positive charge. It is suggested that lysozyme, which is naturally secreted by monocytes and macrophages, might interact with lymphocyte surface receptor sites and participate in the complex mononuclear phagocyte-lymphocyte interactions and in the modulation of lymphocyte activation.

Preliminary characterization of a mutant of herpes simplex virus type 1 selected for acycloguanosine resistance in vitro

In this paper we report on the preliminary characterization of a mutant of herpes simplex virus type 1 (HSV-1) selected for acycloguanosine (acyclovir, ACV) resistance in vitro. The ACVr virus was examined for a series of parameters that include chemosensitivity assay, thymidine kinase (TK) activity, in vitro and in vivo growth, and mutation mapping. The data obtained indicate that a mutated TK gene is responsible for the ACVr phenotype. A distinctive feature of this mutant is the high level of resistance exhibited to ACV (100 microM) and the concomitant presence of a functional TK activity. Such a property makes this virus useful as a model for the study of viral resistance to nucleoside-type analogues in HSV.

DAPI-pUC8 complex: a tool to investigate biological effects of nucleic acid-drug interaction

A complex consisting of pUC8, a 1.8 Md plasmid, and 4'-6-diamidino-2-phenylindole, a DNA-binding agent, has been performed in vitro under different conditions of ionic strength, and used to transform competent cells. A strong interference with the plasmid-coded activities, related to the P/D ratio where at the DNA-drug complex was formed, was shown to occur. Since the compound does not inhibit the uptake process neither affects plasmid activity once dissociated at high ionic strength, it is likely to be acting from inside the cell while still in the form of a DNA-adduct. This system is proposed as a useful tool to investigate the effects on target genes of drugs endowed with DNA sequence specificity.

Antitumor activity of new anthraquinone derivatives

Seven new 9,10-anthracenedione derivatives bearing positively-charged side chains at different positions of the condensed ring system have been investigated in their interaction with DNA and their biological effects, including antitumor activity in the P 388 mouse miniscreen. The drug's affinity for DNA was found to be related to the efficacy of inhibition of cell growth and nucleic acid synthesis for a number of cell lines. Moreover, alkaline elution experiments showed a close relationship between mutagenic potential and cytotoxicity. With the exception of one, all compounds behaved like intercalating agents, as shown by the unwinding of supercoiled plasmid DNA. DNA appeared, therefore, to be the more important target for drug action. The marginal in vivo activity shown by two substances in this series suggests a number of possible structural modifications which may increase their therapeutic efficacy.

Biochemical and physical properties of the endo-beta-N-acetylglucosaminidases from Staphylococcus aureus, Staphylococcus simulans, and Staphylococcus saprophyticus

Biochemical and physical properties of the pure bacteriolytic enzymes excreted by three different Staphylococcus species (S. aureus, S. simulans, and S. saprophyticus) were investigated. Although the three enzymes have previously been shown to share the same specificity of action (endo-beta-N-acetylglucosaminidase activity), their biochemical features clearly indicated that they were three different enzymes, confirming what had previously been suggested by the different lytic-activity patterns displayed by each species and the different procedures needed to achieve purification of each enzyme. Very different values resulted from molecular weight determination: 80,000 for the S. aureus enzyme, 45,000 for the S. simulans enzyme and 31,000 for the S. saprophyticus enzyme. Other important differences were observed in their kinetics of activity on Micrococcus luteus purified cell walls; their stability; their bacteriolytic spectrum against heat-killed cells of various microorganisms; and their response to physical and chemical factors, such as temperature, pH, ionic strength, divalent cations, chelating agents, thiol compounds, and glucose derivatives.

Laboratory and wild-type Klebsiella pneumoniae strains carrying mannose-inhibitable adhesins and receptors for coliphages T3 and T7 are more pathogenic for mice than are strains without such receptors

We have shown previously that Klebsiella pneumoniae receptors for coliphages T3 and T7 also mediate mannose-inhibitable adherence to human epithelial cells and protect bacteria from phagocytosis and intracellular killing by human polymorphonuclear cells. In this paper we analyze the possible role of such mannose-inhibitable adhesins and T3-T7 receptors (MIAT) in K. pneumoniae intraperitoneal pathogenicity for mice. We showed that intraperitoneal pathogenicity for mice of four different Klebsiella strains (one laboratory and three wild-type) that carry the MIAT was approximately 60-fold higher than that of four derivative strains that lost such receptors by spontaneous mutation. The MIAT could be repressed by Klebsiella phage AP3 lysogenic conversion. Two laboratory and two wild-type strains converted by phage AP3 were also approximately 60-fold less pathogenic for mice than parental strains and showed a pathogenicity level equal to that of the MIAT-negative mutants. Studies of protection in mice with anti-whole cell antisera showed that passive immunization against MIAT-positive cells was more protective than immunization against MIAT-negative cells. Studies of protection in mice by both active and passive immunization with lipopolysaccharide and purified outer membrane proteins have shown that the proteins are the most protective outer membrane components. Since it has been shown previously that the Klebsiella receptors for T3-T7 have a proteic component and that an outer membrane protein is missing in the strains resistant to T3-T7 (C. Pruzzo et al., in R. C. Berkely (ed.), Microbial Adhesion to Surfaces, 1980); the latter finding further supports the role of MIAT in the pathogenicity of Klebsiella for mice.

Purification and characterization of three separate bacteriolytic enzymes excreted by Staphylococcus aureus, Staphylococcus simulans, and Staphylococcus saprophyticus

As a further development of previous investigations showing that different staphylococcal species display different bacteriolytic activity patterns (lyogroups), the bacteriolytic enzymes excreted by three different Staphylococcus species, Staphylococcus aureus (lyogroup I), S. simulans (lyogroup II), and S. saprophyticus (lyogroup IV); have been purified and characterized. A representative strain from each species was grown in a preselected medium made of fully dialyzable products. Culture supernatants were collected in the appropriate growth phase. Two different affinity adsorbents were used for enzyme purification. One was obtained by coupling lysozyme-digested pure peptidoglycan from Micrococcus luteus to cyanogen bromide-activated Sepharose 4B. The second affinity adsorbent used was chitin. The S. aureus bacteriolytic enzyme bound to the solubilized peptidoglycan but not to chitin, whereas the opposite was true for the S. simulans enzyme. The bacteriolytic enzyme from S. saprophyticus did not bind to either the Sepharose 4B-peptidoglycan resin or to chitin, and its purification was achieved by two ion-exchange chromatography steps combined with gel filtration. All three enzymes were purified to apparent homogeneity. Their subsequent characterization indicated that all acted as endo-beta-N-acetylglucosaminidases. However, the three glucosaminidases differed significantly in their kinetics of activity and bacteriolytic spectrum against heat-killed cells of a variety of microorganisms. Very different values also resulted from molecular weight determinations: 80,000 for the S. aureus enzyme, 45,000 for the S. simulans enzyme, and 31,000 for the S. saprophyticus enzyme. Other important differences were observed in their stability, optimal pH and ionic strength for their activity, and their responses to temperature and divalent cations. These results confirmed the previous proposal that different staphylococcal species excrete different lytic enzymes.

Production of inhibitors of lytic activity in the Micrococcaceae

Eight Staphylococcus xylosus strains lacking lytic activity (LA) were found to excrete agar-diffusible factors inhibiting the LA of LA-positive strains of the same species. The same eight strains, when tested against LA-positive indicator strains from other species of Micrococcaceae, caused marked LA inhibition only of strains of S, saprophyticus and S. cohnii, both species closely related to S. xylosus. Micrococci and planococci, unlike staphylococci, do not normally show LA, yet Micrococcus lylae and M. sedentarius strains produced inhibitors effective against the LA of almost all the indicator strains, and planococci inhibited the LA of a few indicator strains. Micrococcus luteus strains caused LA inhibition of homologous indicators only, i.e. exceptional M. luteus strains exhibiting LA. Thus, a specific and a non-specific type of LA inhibition can be distinguished, and it is suggested that the apparent lack of LA might, in some instances, be explained by the simultaneous production of a specific inhibitor.

Stimulation of spreading of trypsinized human fibroblasts by lysozymes from Staphylococcus aureus, hen egg white, and human urine

The effect of lysozyme from three different sources--Staphylococcus aureus, hen egg white, and human urine--on adhesion to substrate and spreading of trypsinized human fibroblasts was studied. Several fibroblast strains were tested under various conditions. It was found that the different cell strains did not show the same capability of spreading and stably attaching to substrates when resuspended in media not containing serum. Some strains did not spread, whereas others spread even in the absence of serum. Cell spreading in these strains did not occur when the cells were pregrown for 5 weeks in media supplemented with 1% fetal bovine serum. Lysozyme from S. aureus allowed stable adhesion to substrate and spreading of all the fibroblast strains unable to elongate in nonsupplemented minimal essential medium. This enzyme accelerated and augmented spreading of the strains capable of elongating in the absence of serum. S. aureus lysozyme also allowed spreading and stable adhesion to substrates of all these strains when they were pregrown for 5 weeks in the presence of 1% fetal bovine serum. Furthermore, hen egg white lysozyme and the lysozyme purified from human urine were both capable of stimulating anchorage to substrate and spreading of trypsinized fibroblasts although their effect was less pronounced than that of the S. aureus lysozyme. Some tentative hypotheses for the mechanism of cell spreading in the presence of lysozyme are made. The possibility that lysozymes, virtually ubiquitous enzymes, may play a specific role in nature in the regulation of cell differentiation and tissue development is finally raised and discussed in light of several previous observations and findings.