Management of noninfectious mixed cryoglobulinemia vasculitis: data from 242 cases included in the CryoVas survey

Data on the clinical spectrum and therapeutic management of noninfectious mixed cryoglobulinemia vasculitis (CryoVas) in the era of hepatitis C virus screening are lacking. We analyzed data from 242 patients with noninfectious mixed CryoVas included in the French multicenter CryoVas survey. Baseline manifestations were purpura (75%), peripheral neuropathy (52%), arthralgia or arthritis (44%), glomerulonephritis (35%), cutaneous ulcers (16%), and cutaneous necrosis (14%). A connective tissue disease was diagnosed in 30% and B-cell non-Hodgkin lymphoma in 22%, whereas the CryoVas was considered to be essential in 48%. With the use of Cox-marginal structural models, rituximab plus corticosteroids showed the greater therapeutic efficacy compared with corticosteroids alone and alkylating agents plus corticosteroids to achieve complete clinical, renal, and immunologic responses and a prednisone dosage < 10 mg/d at 6 months. However, this regimen was also associated with severe infections, particularly when high doses of corticosteroids were used, whereas death rates did not differ between the therapeutic regimens. The role of each of these strategies remains to be defined in well-designed randomized controlled trials.     

Factors modulating the delivery and effect of enzymatic cargo conjugated with antibodies targeted to the pulmonary endothelium.

Vascular drug targeting may improve therapies, yet a thorough understanding of the factors that regulate effects of drugs directed to the endothelium is needed to translate this approach into the clinical domain. To define factors modulating the efficacy and effects of endothelial targeting, we used a model enzyme (glucose oxidase, GOX) coupled with monoclonal antibodies (anti-TM(34) or anti-TM(201)) to distinct epitopes of thrombomodulin, a surface determinant enriched in the pulmonary endothelium. GOX delivery results in conversion of glucose and oxygen into H(2)O(2) leading to lung damage, a clear physiologic endpoint. Results of in vivo studies in mice showed that the efficiency of cargo delivery and its effect are influenced by a number of factors including: 1) The level of pulmonary uptake of the targeting antibody (anti-TM(201) was more efficient than anti-TM(34)); 2) The amount of an active drug delivered to the target; 3) The amount of target antigen on the endothelium (animals with suppressed TM levels showed less targeting); and, 4) The substrate availability for the enzyme cargo in the target tissue (hyperoxia augmented GOX-induced injury). Therefore, both activities of the conjugates and biological factors control targeting and effects of enzymatic cargo. Understanding the nature of such "modulating biological factors" will hopefully allow optimization and ultimately applications of drug targeting for "individualized" pharmacotherapy.     

Ketamine inhibits inspiratory-evoked gamma-aminobutyric acid and glycine neurotransmission to cardiac vagal neurons in the nucleus ambiguus

BACKGROUND: Ketamine can be used for perioperative pain management as well as a dissociative anesthetic agent in emergency situations. However, ketamine can induce both cardiovascular and respiratory depression, especially in pediatric patients. Although ketamine has usually been regarded as sympathoexcitatory, recent work has demonstrated that ketamine has important actions on parasympathetic cardiac vagal efferent activity. The current study tests the hypothesis that ketamine, at clinical relevant concentrations, alters central cardiorespiratory interactions in the brainstem and, in particular, the inspiration-evoked increase in gamma-aminobutyric acid-mediated and glycinergic neurotransmission to parasympathetic cardiac efferent neurons. METHODS: Cardiac vagal neurons were identified by the presence of a retrograde fluorescent tracer. Respiratory evoked gamma-aminobutyric acid-mediated and glycinergic synaptic currents were recorded in cardiac vagal neurons using whole cell patch clamp techniques while spontaneous rhythmic respiratory activity was recorded simultaneously. RESULTS:: Ketamine, at concentrations from 0.1 to 10 microM, evoked a concentration-dependent inhibition of inspiratory burst frequency. Inspiration-evoked gamma-aminobutyric acid-mediated neurotransmission to cardiac vagal neurons was inhibited at ketamine concentrations of 0.5 and 1 microM. The increase in glycinergic activity to cardiac vagal neurons during inspiration was also inhibited at ketamine concentrations of 0.5 and 1 microM. CONCLUSIONS: At clinically relevant concentrations (0.5 and 1 microM), ketamine alters central respiratory activity and diminishes both inspiration-evoked gamma-aminobutyric acid-mediated and glycinergic neurotransmission to parasympathetic cardiac efferent neurons. This reduction in inhibitory neurotransmission to cardiac vagal neurons is likely responsible for the compromised respiratory sinus arrhythmia that occurs with ketamine anesthesia.     

Fentanyl inhibits GABAergic neurotransmission to cardiac vagal neurons in the nucleus ambiguus

Fentanyl citrate is a synthetic opiate analgesic often used clinically for neonatal anesthesia. Although fentanyl significantly depresses heart rate, the mechanism of inducing bradycardia remains unclear. One possible site of action is the cardioinhibitory parasympathetic vagal neurons in the nucleus ambiguus (NA), from which originates control of heart rate and cardiac function. Inhibitory synaptic activity to cardiac vagal neurons is a major determinant of their activity. Therefore, the effect of fentanyl on GABAergic neurotransmission to parasympathetic cardiac vagal neurons was studied using whole-cell patch clamp electrophysiology. Application of fentanyl induced a reduction in both the frequency and amplitude of GABAergic IPSCs in cardiac vagal neurons. This inhibition was mediated at both pre- and postsynaptic sites as evidenced by a dual decrease in the frequency and amplitude of spontaneous miniature IPSCs. Application of the selective micro-antagonist CTOP abolished the fentanyl-mediated inhibition of GABAergic IPSCs. These results demonstrate that fentanyl acts on micro-opioid receptors on cardiac vagal neurons and neurons preceding them to reduce GABAergic neurotransmission and increase parasympathetic activity. The inhibition of GABAergic effects may be one mechanism by which fentanyl induces bradycardia.