Structural and functional analysis of the interaction between the agonistic monoclonal antibody Apomab and the proapoptotic receptor DR5

Activation of the proapoptotic receptor death receptor5 (DR5) in various cancer cells triggers programmed cell death through the extrinsic pathway. We have generated a fully human monoclonal antibody (Apomab) that induces tumor cell apoptosis through DR5 and investigated the structural features of its interaction with DR5. Biochemical studies showed that Apomab binds DR5 tightly and selectively. X-ray crystallographic analysis of the complex between the Apomab Fab fragment and the DR5 ectodomain revealed an interaction epitope that partially overlaps with both regions of the Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand binding site. Apomab induced DR5 clustering at the cell surface and stimulated a death-inducing signaling complex containing the adaptor molecule Fas-associated death domain and the apoptosis-initiating protease caspase-8. Fc crosslinking further augmented Apomab's proapoptotic activity. In vitro, Apomab triggered apoptosis in cancer cells, while sparing normal hepatocytes even upon anti-Fc crosslinking. In vivo, Apomab exerted potent antitumor activity as a single agent or in combination with chemotherapy in xenograft models, including those based on colorectal, non-small cell lung and pancreatic cancer cell lines. These results provide structural and functional insight into the interaction of Apomab with DR5 and support further investigation of this antibody for cancer therapy.

Embolie graisseuse pulmonaire après liposuccion

A 24-year-old woman undergoes buttock's liposuction as an outpatient procedure. As she went back home, progressive dyspnea, respiratory distress and collapse developed. At hospital admission, she was dyspneic with thoracic oppression, tachycardia and anguish. Chest X-ray and thoracic CT scan suggested a pulmonary localisation of fat emboli. Symptomatic treatment allowed complete recovery. This report discusses diagnosis of fat emboli after liposuction as well as epidemiology and physiopathology.

[Fiber-optic intubation with non-invasive ventilation with an endoscopic facial mask]

OBJECTIVES

To assess the feasibility and safety of a new technique of fiberoptic bronchoscopy (FOB) tracheal intubation (TI) with noninvasive ventilation (NIV) via an endoscopic full facial mask with two openings, in case of acute respiratory failure (ARF) temporally improved by NIV, but requiring a mechanical ventilation.

STUDY DESIGN

Clinical, prospective, open, noncomparative trial of feasibility with direct individual profit.

PATIENTS

Sixteen patients with ARF (age: 60 +/- 17 years, PaO2 = 59 +/- 16 mmHg, PaCO2 = 64 +/- 26 mmHg, PaO2/FIO2 = 142 +/- 70 before NIV) (m +/- SD), requiring TI. Including were: TI necessity (SpO2 < 90% or hypercapnic despite NIV, dependence of NIV, exhaustion, septic syndrome), clinical and SpO2 improvement with NIV.

METHODS

After i.v. injection of 5 mg midazolam and topical anesthesia (TA) of the nose, the endoscopic mask (modified Fibroxy, Péters) was applied to the face, fixed with elastic straps, then connected to the ventilatory support system with IPAP = 20 cmH2O, EPAP = 5 to 12 cmH2O, FIO2 = 1. A tube was slid on the FOB. As soon as SpO2[[[nbsp] 94%, the extremity of the FOB, was inserted through the lower opening of the mask, slid in the nostril, positioned in front of the glottis for AL, then pushed in the trachea authorizing AL and i.v. injection of 0.15 mg.kg-1 of etomidate (Ramsay[[[nbsp]3). The tube was then slid in the trachea, then, FOB was removed from trachea.

RESULTS

The FOB intubation was easy at the patient's, without any failure or any complication. The procedure was 6.7 +/- 2 min. SpO2 significantly improved during TI, from 84 +/- 5% (FIO2 = 0.6 +/- 3) to 97 +/- 1 (FIO2 = 1 +/- 0), without decrease in oxygen saturation off 90%. Arterial pressure decreased only after the 5th min. The quantities of midazolam and of etomidate used were 4.6 +/- 2 mg and 12 +/- 4 mg. Three patients benefited from EPAP > 10 cmH2O.

CONCLUSION

Fiberoptic tracheal intubation with NIV via an adapted endoscopic facial mask is a safe technique in patient with ARF temporally improved by NIV. This procedure requires TA and conscious sedation.

[Fiberoptic bronchoscopy during noninvasive positive-pressure ventilation in patients with chronic obstructive lung disease with hypoxemia and hypercapnia]

OBJECTIVES

To assess the feasibility and safety of non invasive positive-pressure ventilation (NIPPV) via a face mask to performing fiberoptic bronchoscopy (FOB) in patients with COPD contraindicating FOB in spontaneous ventilation.

STUDY DESIGN

Clinical, prospective, open, non comparative trial of feasibility.

PATIENTS

Ten consecutive COPD patients (71 +/- 5 year-old, PaO2 = 53 +/- 13 mmHg and PaCO2 = 67 +/- 11 mmHg), without any sign of acute respiratory failure, admitted to the intensive care unit for pneumonia requiring a bronchoalveolar lavage (BAL). Including were: PaO2 < 70 mmHg despite nasal O2 delivered at 3 L.min-1, PaCO2 > 50 mmHg, improvement of SpO2 with NIPPV before FOB.

METHODS

Topical anaesthesia of the nose and pharynx was obtained with a 5% lidocaine spray. NIPPV was administered using a ventilatory support system Evita 4 (Dräger) applied through a full facial mask secured to the patient with elastic straps. Patients were first allowed to acclimate for 5 min with NIPPV (IPAP = 16 cmH2O, EPAP = 0 and trigger of 0.3 cm H2O while a FIO2 kept at 0.7). A T-adapter Medisize (Péters) was attached to the facial mask. The tip of the FOB was inserted through the nose. Topical anaesthesia of the vocal cords was obtained with 1% lidocaine solution (3 mL). The FOB was inserted into the trachea up to a bronchial sub-segment. BAL was performed by instillation of 100 mL of saline solution. After FOB, the NIPPV was maintained for 5 min. Heart rate, SpO2 were measured continuously and arterial pressure at 2 min intervals. Arterial blood gas values were obtained just prior NIPPV and after 15 min and 60 min NIPPV disconnection.

RESULTS

FOB duration was 11 +/- 4 min. SpO2 significantly improved during FOB (from de 91 +/- 4.7% to 97% +/- 1.7) without decrease of oxygen saturation lower than 90%. There were no changes in PaCO2 and PaO2 during the hour following the end of procedure. FOB under NIPPV was performed in all patients without complications and was very well tolerated in eight patients. After NPPV disconnecting, one patient required again NIPPV for 15 min. No patient required endotracheal intubation within 24 hours. All patients survived.

CONCLUSION

Application of NIPPV during FOB is a safe technic for maintaining adequate gas exchange in hypoxaemic and hypercapnic COPD patients not in acute respiratory failure. After the end of the procedure a close surveillance in the intensive care unit is essential.

[Cerebral and renal toxicity of acyclovir in a patient treated for meningoencephalitis]

We report the case of a 65-year-old man treated with intravenous acyclovir and amoxicilline for meningoencephalitis. Six days later, he suddenly developed acute renal failure, associated with central nervous system symptoms. The high acyclovir concentration in plasma and spinal fluid confirmed the hypothesis of acyclovir toxicity. Continuous haemofiltration resulted in a rapid amendment of neurologic and renal symptoms. Despite the high therapeutic index of acyclovir, manifestations of neurotoxicity and nephrotoxicity are not a rare event. The risk is increased in the elderly and in patients with renal insufficiency. Rapid intravenous injections are contraindicated. Continuous haemofiltration is rapidly efficient. The value of acyclovir concentration determination in plasma and spinal fluid are stressed.

[Acute interstitial nephritis. Role of ceftazidime]

A 22-year-old man treated with ceftazidime-amikacine for a Pseudomonas aeruginosa pneumonia, experienced two days later allergic symptoms, acute renal failure and urinary sediment abnormalities. The renal biopsy showed an acute interstitial nephritis. Basophils stimulation test was positive for ceftazidime. Early diagnosis and discontinuation of the suspected agent is essential to allow rapid and complete recovery of renal function.

[Laryngeal masks in emergency medicine]

Airway control and maintenance of effective assisted ventilation are an absolute priority in emergency medicine. Developed by Brain in 1988, the laryngeal mask offers a new means of ventilation management and is a reliable compromise between the face mask and endotracheal tubing. The laryngeal mask ensures no protection against gastric contents inhalation and its use is limited in patients with decreased thoracopulmonary compliance. However, compared to the face mask, the laryngeal mask offers several benefits in the management of cardiorespiratory arrests by paramedical staff and rescue teams: the procedure is easy to learn, the device improves airway patency, leaves the operator's hands free, allows endotracheal aspiration to be performed and reduces the risk of hyperinsufflation. These advantages make the use of the laryngeal mask a technique which should be taught to any staff liable to face and manage cases of cardiorespiratory arrest. The laryngeal mask cannot and does not replace endotracheal tubing which remains the only technique that guarantees upper airway patency and protection as well as efficient ventilation control. However, in some situations tubing may prove difficult and even, at times, impossible to perform. This is when the laryngeal mask will come in handy, either as a temporary solution or as an alternative to difficult or impossible tubing techniques.

[Endotracheal intubation under propofol with or without vecuronium]

OBJECTIVE

In order to test the hypothesis that under the association propofol-alfentanil-IV lidocaine the trachea could be intubated easily without an additional muscle relaxant, this study compared the intubation conditions when this association was combined or not with vecuronium.

STUDY DESIGN

Randomized comparative trial.

PATIENTS

The study included 152 young adults classified as ASA physical class I and Mallampati presentation grade 1, randomly allocated either into Vecu+ group or Vécu0 group, depending on whether vecuronium was co-administered or not.

METHODS

All patients received midazolam 0.05 mg.kg-1 i.v., one minute before induction. Those of group Vecu0 were given successively within two minutes: alfentanil 0.03 mg.kg-1, lidocaine 1.5 mg.kg-1 i.v. and propofol 2.5 mg.kg-1. Patients of group Vecu+ received similar doses of alfentanil and propofol as well as vecuronium 0.08 mg.kg-1. The endotracheal tube was inserted one minute after induction in the patients of Vecu0 group, and after three minutes in those of the Vecu+ group. During intubation, scores of mouth opening, glottis opening and coughing were established, in order to assess intubation conditions.

RESULTS

Similar convenient intubating conditions were obtained in both groups (in 97% of patients in Vecu+ group vs 95% of those in Vecu0 group). In the latter, the glottis opening was less pronounced.

CONCLUSIONS

In young healthy adults, without anaesthetic risk (emergency, full stomach) and without foreseen difficult intubation, the endotracheal tube can be inserted in convenient conditions without a muscle relaxant, under the association propofol-alfentanil-lidocaine iv.

Effects of kistrin on bone resorption in vitro and serum calcium in vivo

In many cell systems, cell-cell and cell-matrix interactions are mediated by integrins, a family of cell surface heterodimeric glycoprotein receptors. Osteoclast integrins may play a role in the process of bone resorption. Osteoclasts express the alpha v and beta 3 subunits of the vitronectin receptor and adhere to a wide range of proteins in vitro, all which contain the amino acid sequence Arg-Gly-Asp (RGD), an adhesion site recognition sequence common to many protein ligands that bind to integrins. The effect of kistrin, an RGD-containing snake venom protein, on osteoclast-mediated bone resorption was investigated in vivo and in vitro. When kistrin was infused into normocalcemic and hypercalcemic mice, serum calcium was significantly lowered at 3 and 6 h after the start of infusion, indicating an inhibitory effect on osteoclast activity in vivo. In vitro, kistrin potently inhibited bone resorption by isolated rat osteoclasts cultured on slices of bovine bone, and kistrin also inhibited the attachment of 293 cells expressing recombinant human alpha v beta 3 to fibrinogen (IC50 = 1 nM). These results indicate the potential therapeutic use of RGD-containing molecules for hypercalcemia of malignancy or for other disorders associated with bone loss.

[Treatment of acute colonic pseudoobstruction (Ogilvie's syndrome) by cisapride]

A case is reported of a 68-year-old woman admitted in the ICU for acute exacerbation of a chronic obstructive respiratory disease. The trachea was intubated and the lungs ventilated mechanically. She received sedation including midazolam and phenoperidine 1 mg.h-1. On the 6th day, she experienced a massive colonic dilation (caecal diameter of 10 cm at X-ray examination). A colonoscopy was performed which showed the absence of obstruction, confirmed the diagnosis of pseudo-obstruction of the colon and allowed a decompression which was inefficient. A new colonoscopic decompression was performed on the 8th day, without prolonged effect. At that time, the patient was given cisapride in her gastric tube (80 mg). This treatment restarted the bowel movements within 48 hours and the caecal diameter decreased immediately to 7 cm. Cisapride was maintained for 10 days and mechanical ventilation for 30 days. No further dilation occurred during this time and the patient was discharged from the ICU. Few cases of Ogilvie's syndrome successfully treated with cisapride have been reported in the literature. The efficacy of this agent for the treatment of Ogilvie's syndrome remains to be assessed in a controlled study.

[Severe accidental hypothermia]

Two cases of severe accidental hypothermia (core temperature below 25 degrees C) are reported. Both occurred in an urban area during the same winter period. Both patients had the same age and similar clinical symptoms. In the first patient, the EEG, the echocardiography and the blood gases were in favour of a good tolerance of hypothermia, which led to choice a non aggressive rewarming method. The latter included the rewarming of inhaled gas mixture as well as i.v. fluids and gastro-intestinal lavage fluid. The outcome was uneventful. In the second patient, the visceral and biological consequences were more important (pH: 6.80, blood glucose concentration: 1.48 mmol.L-1, major coagulation disorders). Therefore a rapid rewarming via a cardiopulmonary bypass was preferred. The patient died from a prolonged shock with disseminated intravascular coagulation. The use of cardiopulmonary bypass which is essential in case of cardiac arrest rhythm, is controversial in case of severe hypothermia with a still beating heart.

Pharmacokinetics of recombinant human tumor necrosis factor-alpha in rats. Effects of size and number of doses and nephrectomy

The serum pharmacokinetics of recombinant human tumor necrosis factor-alpha (rHuTNF) were determined in male and female rats under various conditions. The clearance of rHuTNF after iv administration was determined to be saturable over the dose range of 10-63 micrograms/kg. Multiple iv administration did not significantly change the clearance of rHuTNF. Nephrectomy significantly reduced but did not eliminate the clearance of rHuTNF. The data suggest that sites other than the kidney also contribute to the elimination of rHuTNF. Female rats showed significantly reduced clearance of rHuTNF compared to male rats at all doses after single and multiple iv administration in control and nephrectomized animals.