Anti-resorptive therapy and MRONJ. A survey of the Italian Society of Periodontology and Implantology

OBJECTIVES

Anti-resorptive agents have been linked to the development of MRONJ in patients undergoing dental surgical procedures. This survey aims to explore the level of knowledge and experience of Italian Society of Periodontology and Implantology members in the management of patients treated with anti-resorptive agents and with the risk of developing MRONJ.

MATERIALS AND METHODS

An 18-item questionnaire was submitted by e-mail to the SIdP members. Statistical analyses were carried out. Continuous variables were described as mean ± standard deviation (SD) or median, and first and third quartile according to distribution's normality. Normality of data was checked with Shapiro-Wilk test.

RESULTS

Four hundred and fifty-one questionnaires were returned by e-mail (32%). Most of the respondents were private practitioners (81.8%). Only 47.7% declared to be highly confident in managing patients on anti-resorptive therapy while 92.5% reported to have performed tooth extractions and 52.3% implant surgery in patients under anti-resorptive therapy for osteometabolic disorders. One or more MRONJ-affected patients were encountered by 63.2% of the respondents.

CONCLUSIONS

This survey highlights the need to develop a "dedicated" program both for dentists and prescribers to improve the level of cooperation and to increase the level of awareness of patients treated with anti-resorptive agents.

Admission eGFR predicts in-hospital mortality independently of admission glycemia and C-peptide in patients with type 2 diabetes mellitus and COVID-19

OBJECTIVE

Type 2 diabetes mellitus (T2DM) and impaired kidney function are associated with a higher risk of poor outcomes of COVID-19. We conducted a retrospective study in hospitalized T2DM patients with COVID-19 to assess the association between in-hospital mortality and admission values of different hematological/biochemical parameters, including estimated glomerular filtration rate (eGFR), plasma glucose and C-peptide (as a marker of beta-cell function).

METHODS

The study included T2DM patients with confirmed SARS-CoV-2 infection who were consecutively admitted to our Institution between October 1, 2020 and April 1, 2021.

RESULTS

Patients (n = 74) were categorized into survivors (n = 55) and non-survivors (n = 19). Non-survivors exhibited significantly higher median WBC count, D-dimer, neutrophil-to-lymphocyte ratio, hsCRP, and procalcitonin levels, as well as significantly lower median serum 25(OH)D levels compared to survivors. Non-survivors exhibited significantly higher median admission plasma glucose (APG) values compared to survivors (210 vs 166 mg/dL; p = 0.026). There was no statistically significant difference in median values of plasma C-peptide between non-survivors and survivors (3.55 vs 3.24 ng/mL; p = 0.906). A significantly higher percentage of patients with an eGFR < 60 mL/min/1.73 m² was observed in the non-survivor group as compared to the survivor group (57.9% vs 23.6%; p = 0.006). A multivariate analysis performed by a logistic regression model after adjusting for major confounders (age, sex, body mass index, major comorbidities) showed a significant inverse association between eGFR values and risk of in-hospital mortality (OR, 0.956; 95% CI, 0.931-0.983; p = 0.001). We also found a significant positive association between WBC count and risk of in-hospital mortality (OR, 1.210; 95% CI, 1.043-1.404; p = 0.011).

CONCLUSIONS

Admission eGFR and WBC count predict in-hospital COVID-19 mortality among T2DM patients, independently of traditional risk factors, APG and random plasma C-peptide. Hospitalized patients with COVID-19 and comorbid T2DM associated with impaired kidney function at admission should be considered at high risk for adverse outcomes and death.

1045. Longitudinal Evaluation of the QuantiFERON-TB Gold Plus Assay in Hospitalized COVID-19 Patients with a First Indeterminate Result: Resolution of Inflammation and Restoration T-lymphocyte Counts and Interferon-gamma Production

Background

Several studies reported an increased rate of indeterminate QuantiFERON-TB Gold Plus (QFT-P) assay results in patients with severe Coronavirus Disease (COVID)-19.

Methods

Aim of the study was to longitudinally evaluate QFT-P responses in patients who survived COVID-19, with a previous indeterminate result.

Results

We observed 223 patients with an indeterminate QFT-P assay among 949 patients hospitalized because of COVID-19 (23,5%) during 2020 and 2021. 36 patients among those with an indeterminate QFT-P assay were enrolled for reassessing the test. In 12 patients peripheral blood lymphocyte subsets were also reassessed. Considering disease severity, 30 were classified as severe and 6 as non-severe. Median age was 57,5 (interquartile range [IQR]: 49,5-63,8), with a prevalence of male sex (M/F: 24/12); median Charlson Comorbidity Index was 2 (IQR: 1-3). The second QFT-P assay was performed after at least 1 month from the first assay (median time 7 months, IQR: 5-12 months). All QFT-P assays gave a determined result: 2 positive (5.5%) and 34 negatives (94,4%). A statistically significant difference was observed after comparing the laboratory parameters at the time of the first and the second QFT-P assay: the absolute counts of total lymphocyte, total CD3+, CD4+ and CD8+ T-lymphocytes were significantly increased (p&lt; 0.001) while neutrophil absolute counts, neutrophil to lymphocyte (N/L) ratio, D-dimer, fibrinogen, ferritin, C-reactive protein (CRP) were significantly reduced (p&lt; 0.0001). Concerning the QFT-P assay, interferon gamma (INF-γ) production in the Mitogen-Nil, TB1-Nil and TB2-Nil conditions were significantly increased (p&lt; 0.0001; p=0.0019; p=0.0205, respectively) (Table 1 and Figure 1).

Conclusion

Once the acute phase of COVID-19 is resolved, inflammatory markers and peripheral blood leucocyte counts tend to normalize with an effective INF-γ production after specific and nonspecific stimulation. All the 36 QFT-P showed a determinate result. Moreover, we observed 2 positive QFT-P assay, supporting the importance of retesting patients with indeterminate result to identify latent tuberculosis infection and monitor patients for possible reactivation because of the immune-suppression associated with COVID-19.

Disclosures

All Authors: No reported disclosures.

In Patients with Severe COVID-19, the Profound Decrease in the Peripheral Blood T-Cell Subsets Is Correlated with an Increase of QuantiFERON-TB Gold Plus Indeterminate Rates and Reflecting a Reduced Interferon-Gamma Production

Increased rates of indeterminate QuantiFERON-TB Gold Plus Assay (QFT-Plus) were demonstrated in patients hospitalized with Coronavirus Disease (COVID)-19. We aimed to define the prevalence and characteristics of hospitalized COVID-19 patients with indeterminate QFT-Plus. A retrospective study was performed including hospitalized COVID-19 patients, stratified in survivors and non-survivors, non-severe and severe according to the maximal oxygen supply required. Statistical analysis was performed using JASP ver0.14.1 and GraphPad Prism ver8.2.1. A total of 420 patients were included, median age: 65 years, males: 66.4%. The QFT-Plus was indeterminate in 22.1% of patients. Increased rate of indeterminate QFT-Plus was found in non-survivors (p = 0.013) and in severe COVID-19 patients (p < 0.001). Considering the Mitogen-Nil condition of the QFT-Plus, an impaired production of interferon-gamma (IFN-γ) was found in non-survivors (p < 0.001) and in severe COVID-19 patients (p < 0.001). A positive correlation between IFN-γ levels in the Mitogen-Nil condition and the absolute counts of CD3+ (p < 0.001), CD4+ (p < 0.001), and CD8+ (p < 0.001) T-lymphocytes was found. At the multivariable analysis, CD3+ T-cell absolute counts and CD4/CD8 ratio were confirmed as independent predictors of indeterminate results at the QFT-Plus. Our study confirmed the increased rate of indeterminate QFT-Plus in COVID-19 patients, mainly depending on the peripheral blood T-lymphocyte depletion found in the most severe cases.

Baseline T-lymphocyte subset absolute counts can predict both outcome and severity in SARS-CoV-2 infected patients: a single center study

The aim of this study was to evaluate the role of baseline lymphocyte subset counts in predicting the outcome and severity of COVID-19 patients. Hospitalized patients confirmed to be infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were included and classified according to in-hospital mortality (survivors/nonsurvivors) and the maximal oxygen support/ventilation supply required (nonsevere/severe). Demographics, clinical and laboratory data, and peripheral blood lymphocyte subsets were retrospectively analyzed. Overall, 160 patients were retrospectively included in the study. T-lymphocyte subset (total CD3+, CD3+ CD4+, CD3+ CD8+, CD3+ CD4+ CD8+ double positive [DP] and CD3+ CD4− CD8− double negative [DN]) absolute counts were decreased in nonsurvivors and in patients with severe disease compared to survivors and nonsevere patients (p < 0.001). Multivariable logistic regression analysis showed that absolute counts of CD3+ T-lymphocytes < 524 cells/µl, CD3+ CD4+ < 369 cells/µl, and the number of T-lymphocyte subsets below the cutoff (T-lymphocyte subset index [TLSI]) were independent predictors of in-hospital mortality. Baseline T-lymphocyte subset counts and TLSI were also predictive of disease severity (CD3+  < 733 cells/µl; CD3+ CD4+ < 426 cells/µl; CD3+ CD8+ < 262 cells/µl; CD3+ DP < 4.5 cells/µl; CD3+ DN < 18.5 cells/µl). The evaluation of peripheral T-lymphocyte absolute counts in the early stages of COVID-19 might represent a useful tool for identifying patients at increased risk of unfavorable outcomes.

Gender-related differential effect of tachykinin NK2 receptor-mediated visceral hyperalgesia in guinea pig colon

BACKGROUND AND PURPOSE

The tachykinin NK2 receptor antagonist ibodutant is under Phase III clinical investigation to treat female patients with irritable bowel syndrome. The aim of this study was to investigate the NK2 receptor-related gender specificity in a model of colitis.

EXPERIMENTAL APPROACH

Colitis was induced by rectal instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS, 0.5 mL, 30 mg·mL(-1) in 30% ethanol) in female and male guinea pigs. Electromyographic recording of the responses to colorectal distension (CRD) was made 3 days later. Ibodutant (0.33 , 0.65, 1.9 and 6.5 mg·kg(-1) ) was given s.c., 30 min before CRD. Release of neurokinin A and substance P from isolated mucosal and smooth muscle tissues following treatment with KCl (80 mM) or capsaicin (10 μM) was measured by EIA. Plasma pharmacokinetics of ibodutant following a single s.c. administration (0.73 or 2.1 mg·kg(-1) ) were measured over 24 h.

KEY RESULTS

Ibodutant did not affect abdominal contractions in control animals. After TNBS-induced colitis, ibodutant prevented the increased visceral hypersensitivity to CRD in females, at lower doses than in males. Ibodutant pharmacokinetics did not differ between females and males. Tachykinins release was greater in smooth muscle than in mucosal samples. Capsaicin-stimulated release of tachykinins from inflamed mucosal samples from females was significantly lower than in males.

CONCLUSIONS AND IMPLICATIONS

Ibodutant prevented abdominal nociception in a model of visceral hypersensitivity in guinea pigs with a greater efficacy in females than in males. Our results highlight a gender-related difference in colonic visceral hypersensitivity and mucosal nerve activation.

Root caries: a periodontal perspective

BACKGROUND AND OBJECTIVE

A prevailing dental problem in the periodontal patient is root caries. Specifically, periodontal involvement often results in root surfaces becoming exposed and at risk for this condition. Periodontal therapy often leads to increased gingival recession as well, and the associated increased root caries risk may compromise the long-term success and survival of periodontally treated teeth.This narrative review will address the topic of root caries in the periodontal patient, focusing on unmet research needs.

MATERIAL AND METHODS

The Medline database was searched to identify items dealing with root caries, in terms of clinical features, diagnosis, pathogenic mechanisms and histopathology, as well as epidemiology, focusing then on the relationship between root caries and periodontal disorders.

RESULTS

Although there is extensive literature on root caries, consensus is lacking regarding certain aspects, such as diagnostic criteria, prevalence within populations and indisputable risk factors. Advancing age could be an aggravating factor in susceptibility to root caries for the periodontal patient; however, definitive evidence in this regard is still missing. Similarly, full awareness of the increased risk of root caries in patients with periodontal disease or long-term periodontal treatment appears to be still lacking.

CONCLUSION

Research regarding root caries in age-specific (elderly) periodontal patients is needed. Improved oral hygiene practices, locally applied preventive measures, good dietary habits and regular dental check-ups are crucial approaches to prevent both periodontal disease progression and root caries. Periodontal patients with root exposure should follow a strict root caries prevention protocol, as an integral component of their periodontal maintenance therapy.

Antitumour effect of combination treatment with Sabarubicin (MEN 10755) and cis-platin (DDP) in human lung tumour xenograft

PURPOSE

Sabarubicin (MEN 10755), a new disaccaride anthracycline, has shown greater efficacy than Doxorubicin in a large panel of preclinical models and now it is in phase II clinical trials. Its promising antitumour activity promoted considerable interest to combine Sabarubicin with other antitumour agents. Thus, the purpose of this study was to evaluate in vitro cytotoxic effects and in vivo antitumour activities produced by the combination of Sabarubicin and cisplatin (DDP).

METHODS

The antitumour effect of Sabarubicin and DDP association was investigated, in vitro and in vivo, in preclinical models of lung cancer i.e.: the non-small cell lung carcinoma (NSCLC) H460 and the small-cell lung carcinoma (SCLC) GLC4 in terms of synergism, additivity or antagonism in order to establish the best schedule for the combined treatment. Further, the correlation between antitumour activity and the pharmacokinetic parameters of the studied combination was also evaluated.

RESULTS

The drug combination in vitro was in general more cytotoxic than the single drug alone, indicating the presence of a synergistic effect in both tumour cell lines. Also, in the xenograft experiments a superior antitumoral effect was observed when Sabarubicin was combined with DDP. The antitumour efficacy of Sabarubicin (6 mg/kg q4d x 5) combined with DDP (6 mg/kg q4d x 3) greatly depended on the schedule of administration. In H460 tumour line, the sequential combination was more effective than the simultaneous administration of the two agents, although the antitumour efficacy was not dependent on the sequence of combination. On the other hand, a strong sequence-dependent effect was observed when Sabarubicin was combined with DDP in SCLC, GLC4. In particular, the highest value of LCK = 6.7 was obtained when administration of DDP followed by 24 h that of Sabarubicin. Pharmacokinetics of Sabarubicin in combination with DDP was evaluated at 6 mg/kg for both drugs with different sequential schedule. The experimental data showed no evidence for pharmacokinetics drug-drug interaction.

CONCLUSION

These preclinical results indicate the potential for a strong antitumour activity in lung tumours of the combination Sabarubicin and DDP. In particular, in SCLC the best response should be given by a sequence with administration of Sabarubicin followed 24 h later by that of DDP. Clinical trials based on these results are ongoing.

Heterogeneous effect of leucotriene CysLT1receptor antagonists on antigen-induced motor and inflammatory responses in guinea-pig airways

1. The effect of montelukast or MEN91507, selective leucotriene CysLT1 receptor antagonists, on antigen-induced airway inflammation and bronchoconstriction were compared in anaesthetized guinea-pigs. 2. In sensitized animals, ovalbumin (0.3 mg kg(-1), i.v.)-induced microvascular leakage in trachea, intrapulmonary airways, total lung (parenchyma and intrapulmonary airways) and urinary bladder was reduced by MEN91507 (0.01-1 micromol kg(-1), i.v.), whereas montelukast (0.01-1 micromol kg(-1), i.v.) antagonized the effect of the antigen only in the lung and urinary bladder. 3. Ovalbumin (1 mg kg(-1), i.v.)-induced bronchoconstriction was dose dependently antagonized by MEN91507 (10-30 micromol kg(-1), i.v.), whereas the effect of montelukast (0.1-30 micromol kg(-1), i.v.) was marginal (15-30% inhibition). Neither MEN91507 nor montelukast (30 micromol kg(-1), i.v.) affected the bronchoconstrictor response induced by acetylcholine (0.3 micromol kg(-1), i.v.) in sensitized animals. 4. It is concluded that montelukast and MEN91507 display a differential activity against the effect of endogenous leucotrienes, despite the fact that both compounds show a similar antagonist profile against exogenous leucotrienes acting through CysLT1 receptors.

Pharmacokinetics of dexketoprofen trometamol in subjects with mild and moderate chronic renal insufficiency

The influence of mild to moderate chronic renal insufficiency on the pharmacokinetics of dexketoprofen trometamol was evaluated. Dexketoprofen was administered to volunteers with mild (n = 8) or moderate (n = 8) renal impairment and to healthy subjects (n = 8), as a single 12.5 mg oral dose (equivalent to 18.5 mg of the tromethamine salt). All subjects completed the study and no serious adverse events were recorded. Mild and moderate renal insufficiency increased Cmax by approximately 22% and 37%, respectively, as related to normal subjects (p < 0.05 for moderate renal dysfunction). No statistically significant differences between groups were obtained for tmax, AUC, CL/F, renal CL and V/F. The cumulative urinary excretion of unchanged dexketoprofen, assessed up to 24 hours postdose, was similar in all groups (median values of 7.0%, 8.1% and 9.7% of the administered dose). On the contrary, cumulative urinary excretions of conjugated dexketoprofen decreased in subjects with mild or moderate renal insufficiency when compared to healthy controls (median and 95% CI for differences: -3.3% (-14.8% to 2.6%) and -7.3% (-22.2% to -0.2%), respectively). Conservatively, a dose adjustment of dexketoprofen in patients with impaired renal function is recommended.

Single and repeated dose pharmacokinetics of dexketoprofen trometamol in young and elderly subjects

Dexketoprofen trometamol, a high water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug (NSAID) widely used for pain relief. This study was conducted to determine the pharmacokinetics of this analgesic agent in elderly subjects and to compare them with young volunteers following single and repeated oral doses. Twelve healthy young and 12 elderly subjects received 25 mg oral dexketo- profen (equivalent to 37 mg of its tromethamine salt) as a single dose (day 1) and 3-day repeated doses (1 dose every 8 h for a total of 10 doses). Serial concentrations of dexketoprofen were determined in plasma and urine by a reverse-phase HPLC/ultraviolet procedure over 24 h on day 1 and after the last 10th repeated t.i.d. dose. Compared to young subjects, elderly subjects showed significant increases in AUC and t1/2,z and decreases in CL/F following single and repeated doses. After single dosing, the corresponding mean +/- SD values were 5106.6 +/- 1873.0 vs. 3605.4 +/- 897.9 ng.h/ml (p = 0.015); 1.59 +/- 0.40 vs. 1.12 +/- 0.20 h (p < 0.001); and 1.11 +/- 0.29 vs. 1.63 +/- 0.36 ml/min/kg (p < 0.001). After the repeated dose, AUC, t1/2,z and CL/F averaged 5067.8 +/- 1373.4 vs. 3194.4 +/- 694.3 ng.h/ml (p < 0.001); 1.65 +/- 0.44 vs. 1.11 +/- 0.29 h (p < 0.005); and 1.12 +/- 0.23 vs. 1.87 +/- 0.42 ml/min/kg (p < 0.001). Median tmax was 0.5 h. Cumulative excretions in urine up to 24 h of unbound, conjugated and total dexketoprofen were similar among the groups. These results suggest that dexketoprofen elimination is reduced in the elderly. Although no drug accumulation in plasma was observed after single and repeated dosing, the renal function decline in elderly patients calls for a cautious dose-adjustment in this population.

Single and repeated dose pharmacokinetics of dexketoprofen trometamol in patients with impaired liver function

Dexketoprofen trometamol, a high water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug (NSAID) used for pain relief. This study compared the pharmacokinetics of dexketoprofen in patients with impaired liver function and normal subjects following single and repeated oral dosing. Subjects with normal liver function (n = 6) and with Child-Pugh A (n = 7) or Child-Pugh B (n = 5) hepatic impairment scores completed this open-label and parallel study. They received 25 mg dexketoprofen (equivalent to 37 mg of its tromethamine salt) as a single (day 1) and a 3-day repeated dose (1 dose every 8 hours for a total of 10 doses). Dexketoprofen concentrations were determined in plasma and urine by reverse-phase high performance liquid chromatography (HPLC). Model-independent pharmacokinetic parameters were obtained. All subjects completed the study. No serious adverse events were recorded. Following the single dose, mean (+/- SEM) Cmax were 3027.7 +/- 429.3 ng/ml (healthy subjects), 2856.3 +/- 340.3 ng/ml (Child-Pugh A) and 1937.2 +/- 328.0 ng/ml (Child-Pugh B). Median tmax were 0.49 h (0.33-0.68) h, 0.50 h (0.33-0.67) h and 0.67 h (0.33-1.50) h. AUC0-x averaged 3778.0 +/- 439.0 ng.h/ml, 4890.4 +/- 539.1 ng.h/ml and 3985.0 +/- 712.0 ng.h/ml. Mean CL/F were 101.1 +/- 11.3 ml/h/kg, 73.3 +/- 9.9 ml/h/kg and 88.8 +/- 15.5 ml/h/kg and V/F averaged 0.192 +/- 0.018 l/kg, 0.162 +/- 0.006 l/kg and 0.214 +/- 0.044 l/kg. Following the repeated administration, similar results were obtained showing no drug accumulation. As related to the administered dose, median excretions of unchanged and conjugated dexketoprofen in urine were 2.1% and 67.1% in healthy subjects, 2.8% and 60.9% in Child-Pugh A subjects and 4.4% and 47.7% in Child-Pugh B volunteers. A trend towards a reduced urinary excretion of conjugated dexketoprofen in hepatic patients, more evident in the Child-Pugh B than in the Child-Pugh A groups, was observed when compared with healthy volunteers (median and 95% CI for differences: -5.4% [-19.9% to 2.0%] and -19.4% [-45.6% to 0.4%]). Conservatively, a dose adjustment of dexketoprofen trometamol in patients with impaired hepatic function is recommended.

Clinical pharmacokinetics of parenteral dexketoprofen trometamol in healthy subjects

Dexketoprofen trometamol, a highly water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug used for pain relief. Two studies were conducted to determine the pharmacokinetics of the drug in healthy subjects following single intravenous (i.v.) and intramuscular (i.m.) doses of dexketoprofen. In the first study, 6 male and 6 female volunteers received 50 mg dexketoprofen (74 mg dexketoprofen trometamol) by i.v. bolus. In the second one, another 6 male and 6 female subjects received 25 mg and 50 mg of dexketoprofen by the i.m. route. Dexketoprofen plasma concentrations were determined by reverse-phase high-performance liquid chromatography (HPLC). No serious adverse events were observed and all volunteers completed the study. The main pharmacokinetic parameters were determined by a noncompartmental approach. Following the i.v. bolus, mean (+/- SEM) area under the curve AUC0-x and clearance (CL) were 9005 +/- 422 ng.h/ml and 0.089 +/- 0.004 l/h/kg. Volumes of distribution Vi and Vss averaged 0.060 +/- 0.006 l/kg and 0.104 +/- 0.003 l/kg. Mean elimination half-life (t1/2e) and MRT were 1.05 +/- 0.04 h and 1.18 +/- 0.05 h. Following single i.m. 25 mg and 50 mg dexketoprofen, a rapid absorption was observed, with tmax values ranging from 0.17 h to 0.75 h. The corresponding Cmax averaged 1851 +/- 182 ng/ml and 3813 +/- 169 ng/ml, and mean AUC0-x were 3033 +/- 193 ng.h/ml and 5878 +/- 228 ng.h/ml, respectively. No significant differences by gender were obtained following both parenteral routes. A dose proportionality in Cmax and AUC0-x was observed. Dexketoprofen pharmacokinetics following i.v. and i.m. routes, together with the availability of a single 2 ml formulation, allows for a potential advantageous rapid switch to the oral formulation when clinically possible.

Nepadutant pharmacokinetics and dose-effect relationships as tachykinin NK2 receptor antagonist are altered by intestinal inflammation in rodent models

Tachykinin NK2 receptor antagonists could reduce motility and symptoms during gastrointestinal diseases characterized by local inflammation such as diarrhea or colitis; however, how these conditions change pharmacodynamic and pharmacokinetic characteristics of NK2 receptor antagonists is unknown. We investigated the effect of the peptide NK2 receptor antagonist nepadutant on spontaneous intestinal motility or [betaAla8]NKA(4-10)-induced colonic and bladder contractions in rodent models of intestinal inflammation (enteritis induced by castor oil and rectocolitis induced by local instillation of acetic acid in rats, enteritis induced by bacterial toxins in mice). In the castor oil model, the oral/intraduodenal bioavailability of nepadutant was also determined. The intrarectal (i.r.) administration of nepadutant (100 nmol/kg) did not reduce [betaAla8]NKA(4-10) (10 nmol/kg i.v.)-induced colonic and bladder contractions in normal animals, but the same dose of nepadutant produced an inhibitory effect in the two organs following rectocolitis; in contrast, nepadutant is equieffective by the intravenous route in normal and colitic animals. In this model, nepadutant (100 nmol/kg i.r. or i.v.) decreased spontaneous colonic hypermotility, without affecting motility in controls. The intraduodenal administration of nepadutant (30 nmol/kg), which was ineffective on [betaAla8]NKA(4-10) (10 nmol/kg i.v.)-induced colonic and bladder contractions in control animals, abolished bladder contractions in castor oil-pretreated animals. In this latter group, the oral and intraduodenal bioavailability of nepadutant showed a 7- to 9-fold increase with respect to controls. Oral administration of nepadutant, in nanomolar or subnanomolar dosage, reduced diarrhea induced by bacterial toxins in mice. It is concluded that intestinal inflammation increases nepadutant absorption in the intestine, enhancing its activity. These results suggest that a drug with a limited oral bioavailability could be used for treating gastrointestinal diseases associated with a local inflammation.

Synthesis and biological activity of the penem antibiotic MEN 10700 and its orally absorbed ester MEN 11505

The synthesis and biological properties of the new penem antibiotic MEN 10700 (6) and of its selected oral prodrug MEN 11505 (8f) are described. MEN 10700 showed a broad spectrum of activity, with high potency both on Gram-positive and Gram-negative strains. It also exhibited good antibacterial activity toward anaerobes and on strains selected for their resistance to other antibacterial agents (cefotaxime- or ceftazidime-resistant Gram-negative strains, ciprofloxacin-resistant E. coli, extended spectrum beta-lactamase producing and cephalosporinase inducible enterobacteria). MEN 10700 showed a very high stability to enzymatic degradation by renal dehydropeptidase DHP-I. After oral administration in rats of the pivaloyloxymethyl ester prodrug MEN 11505, the relative bioavailability of MEN 10700 was calculated as F=43%.

[In vitro activity of ciprofloxacin and ofloxacin against Mycobacterium tuberculosis, M. avium, M. africanum, M. kansasii and BCG strains]

The in vitro activity of ciprofloxacin and ofloxacin against 33 strains of mycobacteria was investigated in a comparative study. The resulting MIC values were compared with serum levels, measured in a cross-over study. Possible therapeutic application of these substances in mycobacterial infections are being discussed. We found the antimycobacterial activity of ciprofloxacin to be insufficient for its clinical application, whereas the corresponding MIC values for ofloxacin could be achieved in vivo. Further animal and clinical studies appear justified.

The metabolism of leukotrienes in blood plasma studied by high-performance liquid chromatography

The metabolism of leukotrienes (B4, C4, D4, and E4) within human plasma was studied and a simple sample preparation is presented. It was demonstrated that leukotriene E4 and leukotriene B4 were stable during incubation at 37 degrees C using the in vitro system. In contrast, leukotriene C4 was metabolized by gamma-glutamyl transpeptidase activities into leukotriene D4 which was further metabolized by dipeptidase activities of plasma into leukotriene E4. The transition state inhibitor of gamma-glutamyl transpeptidase L-serine-borate decreased the metabolism of leukotriene C4 in plasma. Dilution of plasma demonstrated that the dipeptidase was more active compared to the gamma-glutamyl transpeptidase. The metabolizing activities of plasma were functionally characterized by fractionating the plasma proteins.

Generation of slow-reacting substance (leukotrienes) by endotoxin and lipid A from human polymorphonuclear granulocytes

Leukotrienes were released from human polymorphonuclear granulocytes on incubation with endotoxins and lipid A. The analysis was performed by their smooth muscle contracting properties, reversed phase high-pressure liquid chromatography and radioimmunoassay for leukotrienes C4 and D4. The active component of the lipopolysaccharides seems to be the lipid A portion.

Generation of leukotrienes from human granulocytes by alveolysin from Bacillus alvei

We investigated the effect of alveolysin on human granulocytes. Alveolysin is an exoprotein produced by Bacillus alvei and belongs to the group of sulfhydryl-activated cytolysins. Other members of this group are streptolysin O and theta-toxin from Clostridium perfringens. It is demonstrated that alveolysin leads to leukotriene generation from human granulocytes, which exert chemotactic (leukotriene B4) and slow-reacting substance (leukotriene C4, D4, and E4) activity under sublytic concentrations.

Subcellular localization of enzymes involved in leukotriene formation within human polymorphonuclear granulocytes

The subcellular localization of enzymes involved in leukotriene formation was analysed according to biological (chemotaxis, spasmogenic properties) and analytical methods. By subcellular fractionation the major activity for 5--lipoxygenase and L-gamma-glutamyltranspeptidase coeluted with the 200,000 g precipitate while glutathione-S-transferase activity was mainly present in the 200,000 g supernatant. Our data were supported by results indicating that the 200,000 g precipitate and supernatant fractions proved to be most active in generating 5-HETE and leukotriene C4 (LTC4) respectively. The 200,000 g pellet was the most active fraction in transforming synthetic LTC4 into LTD4 and LTE4. When synthetic LTD4 was incubated with the various subcellular fractions and the appearance of LTE4 was analysed the 20,000 and 200,000 g pellets were the most potent fractions. Several discrepancies observed using biological, biochemical and analytical (synthetic substrates) methods may be in part due to the formation of leukotriene isomers which interfere with the biological assays.

Generation of leukotrienes and lipoxygenase factors from human polymorphonuclear granulocytes during bacterial phagocytosis and interaction with bacterial exotoxins

The generation and release of lipoxygenase factors and leukotrienes from human polymorphonuclear granulocytes is demonstrated during bacterial phagocytosis and interaction with bacterial exotoxins (alpha-toxin, enterotoxin, lipase from Staph. aureus; Streptolysin O; cytotoxin from Pseudomonas aeruginosa). The leukotrienes released during stimulation exert chemotactic properties for human neutrophils and guinea pig eosinophils (leukotriene B4) and show the characteristic profile of slow reacting substance activity which is induced by leukotriene C4, D4 and E4. The toxin induced spasmogenic activity obtained from human PMNs was inhibited in the presence of the SRS-antagonist FPL 55712. The generation of lipoxygenase factors is also demonstrated by autoradiography using 14C arachidonic acid prelabelled granulocytes.