Real-World Clinical Experience With Idebenone in the Treatment of Leber Hereditary Optic Neuropathy

BACKGROUND

Leber hereditary optic neuropathy (LHON) leads to bilateral central vision loss. In a clinical trial setting, idebenone has been shown to be safe and to provide a trend toward improved visual acuity, but long-term evidence of effectiveness in real-world clinical practice is sparse.

METHODS

Open-label, multicenter, retrospective, noncontrolled analysis of long-term visual acuity and safety in 111 LHON patients treated with idebenone (900 mg/day) in an expanded access program. Eligible patients had a confirmed mitochondrial DNA mutation and had experienced the onset of symptoms (most recent eye) within 1 year before enrollment. Data on visual acuity and adverse events were collected as per normal clinical practice. Efficacy was assessed as the proportion of patients with either a clinically relevant recovery (CRR) or a clinically relevant stabilization (CRS) of visual acuity. In the case of CRR, time to and magnitude of recovery over the course of time were also assessed.

RESULTS

At time of analysis, 87 patients had provided longitudinal efficacy data. Average treatment duration was 25.6 months. CRR was observed in 46.0% of patients. Analysis of treatment effect by duration showed that the proportion of patients with recovery and the magnitude of recovery increased with treatment duration. Average gain in best-corrected visual acuity for responders was 0.72 logarithm of the minimal angle of resolution (logMAR), equivalent to more than 7 lines on the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. Furthermore, 50% of patients who had a visual acuity below 1.0 logMAR in at least one eye at initiation of treatment successfully maintained their vision below this threshold by last observation. Idebenone was well tolerated, with most adverse events classified as minor.

CONCLUSIONS

These data demonstrate the benefit of idebenone treatment in recovering lost vision and maintaining good residual vision in a real-world setting. Together, these findings indicate that idebenone treatment should be initiated early and be maintained more than 24 months to maximize efficacy. Safety results were consistent with the known safety profile of idebenone.

Rating disease progression of Friedreich's ataxia by the International Cooperative Ataxia Rating Scale: analysis of a 603-patient database

The aim of this cross-sectional study was to analyse disease progression in Friedreich's ataxia as measured by the International Cooperative Ataxia Rating Scale. Single ratings from 603 patients with Friedreich's ataxia were analysed as a function of disease duration, age of onset and GAA repeat lengths. The relative contribution of items and subscales to the total score was studied as a function of disease progression. In addition, the scaling properties were assessed using standard statistical measures. Average total scale progression per year depends on the age of disease onset, the time since diagnosis and the GAA repeat length. The age of onset inversely correlates with increased GAA repeat length. For patients with an age of onset ≤14 years associated with a longer repeat length, the average yearly rate of decline was 2.5 ± 0.18 points in the total International Cooperative Ataxia Rating Scale for the first 20 years of disease duration, whereas patients with a later onset progress more slowly (1.8 ± 0.27 points/year). Ceiling effects in posture, gait and lower limb scale items lead to a reduced sensitivity of the scale in the severely affected population with a total score of >60 points. Psychometric scaling analysis shows generally favourable properties for the total scale, but the subscale grouping could be improved. This cross-sectional study provides a detailed characterization of the International Cooperative Ataxia Rating Scale. The analysis further provides rates of change separated for patients with early and late disease onset, which is driven by the GAA repeat length. Differences in the subscale dynamics merit consideration in the design of future clinical trials applying this scale as a neurological assessment instrument in Friedreich's ataxia.

A randomized placebo-controlled trial of idebenone in Leber's hereditary optic neuropathy

Major advances in understanding the pathogenesis of inherited metabolic disease caused by mitochondrial DNA mutations have yet to translate into treatments of proven efficacy. Leber’s hereditary optic neuropathy is the most common mitochondrial DNA disorder causing irreversible blindness in young adult life. Anecdotal reports support the use of idebenone in Leber’s hereditary optic neuropathy, but this has not been evaluated in a randomized controlled trial. We conducted a 24-week multi-centre double-blind, randomized, placebo-controlled trial in 85 patients with Leber’s hereditary optic neuropathy due to m.3460G>A, m.11778G>A, and m.14484T>C or mitochondrial DNA mutations. The active drug was idebenone 900 mg/day. The primary end-point was the best recovery in visual acuity. The main secondary end-point was the change in best visual acuity. Other secondary end-points were changes in visual acuity of the best eye at baseline and changes in visual acuity for both eyes in each patient. Colour-contrast sensitivity and retinal nerve fibre layer thickness were measured in subgroups. Idebenone was safe and well tolerated. The primary end-point did not reach statistical significance in the intention to treat population. However, post hoc interaction analysis showed a different response to idebenone in patients with discordant visual acuities at baseline; in these patients, all secondary end-points were significantly different between the idebenone and placebo groups. This first randomized controlled trial in the mitochondrial disorder, Leber’s hereditary optic neuropathy, provides evidence that patients with discordant visual acuities are the most likely to benefit from idebenone treatment, which is safe and well tolerated.

Effect of calpain and proteasome inhibition on Ca2+-dependent proteolysis and muscle histopathology in the mdx mouse

Dystrophin deficiency is the underlying molecular cause of progressive muscle weakness observed in Duchenne muscular dystrophy (DMD). Loss of functional dystrophin leads to elevated levels of intracellular Ca(2+), a key step in the cellular pathology of DMD. The cysteine protease calpain is activated in dystrophin-deficient muscle, and its inhibition is regarded as a potential therapeutic approach. In addition, previous work has shown that the ubiquitin-proteasome system also contributes to muscle protein breakdown in dystrophic muscle and, therefore, also qualifies as a potential target for therapeutic intervention in DMD. The relative contribution of calpain- and proteasome-mediated proteolysis induced by increased Ca(2+) levels was characterized in cultured muscle cells and revealed initial Ca(2+) influx-dependent calpain activity and subsequent Ca(2+)-independent activity of the ubiquitin-proteasome system. We then set out to optimize novel small-molecule inhibitors that inhibit both calpain as well as the 20S proteasome in a cellular system with impaired Ca(2+) homeostasis. On administration of such inhibitors to mdx mice, quantitative histological parameters improved significantly, in particular with compounds strongly inhibiting the 20S proteasome. To investigate the role of calpain inhibition without interfering with the ubiquitin-proteasome system, we crossed mdx mice with transgenic mice, overexpressing the endogenous calpain inhibitor calpastatin. Although our data show that proteolysis by calpain is strongly inhibited in the transgenic mdx mouse, this calpain inhibition did not ameliorate muscle histology. Our results indicate that inhibition of the proteasome rather than calpain is required for histological improvement of dystrophin-deficient muscle. In conclusion, we have identified novel proteasome inhibitors that qualify as potential candidates for pharmacological intervention in muscular dystrophy.

Homology models of dipeptidyl peptidases 8 and 9 with a focus on loop predictions near the active site

Dipeptidyl peptidase 4 (DP4) inhibitors are currently under intensive investigation in late-stage clinical trials as a treatment for type II diabetes. Lack of selectivity toward the related enzymes DP8 and DP9 has recently emerged as a possible source of drug-induced toxicity. Unlike DP4, X-ray structures of DP8 and DP9 are not yet available. As an aid to understanding the structural basis for selectivity, the authors have constructed homology models of DP8 and DP9 based on the X-ray coordinates of DP4. Accurate sequence alignment reveals common structural features indicative for a well-preserved overall fold comprising two domains, namely, a hydrolase domain and a so-called beta-propeller, which together form the active site deeply buried within the protein. The conformation of two loops inside this deep cavity is particularly relevant for the active sites. The authors used a published protocol for loop prediction based on conformational sampling and energy analysis to generate plausible solutions for these two loops. The predictive power of the approach was successfully evaluated for the template protein DP4 and two additional known structures from the same protein family, namely, FAP and DPX. The authors also show that inclusion of the covalent ligand NVP-728 greatly enhances the refinement. Based on the established evaluation protocol, the corresponding loops of DP8 and DP9 were predicted and the resulting active sites were compared with DP4. In particular, the authors conclude that differences in the P2-pocket are relevant for the design of selective DP4 inhibitors. The loss of key interactions in DP8 and DP9 as predicted from their models is consistent with the selectivity profile of the DP4 clinical candidate MK-431.

The reversed binding of β-phenethylamine inhibitors of DPP-IV: X-ray structures and properties of novel fragment and elaborated inhibitors

The co-crystal structure of beta-phenethylamine fragment inhibitor 5 bound to DPP-IV revealed that the phenyl ring occupied the proline pocket of the enzyme. This finding provided the basis for a general hypothesis of a reverse binding mode for beta-phenethylamine-based DPP-IV inhibitors. Novel inhibitor design concepts that obviate substrate-like structure-activity relationships (SAR) were thereby enabled, and novel, potent inhibitors were discovered.

In silico fragment-based discovery of DPP-IV S1 pocket binders

Dipeptidyl peptidase IV is a clinically validated target for type-2 diabetes and belongs to a family of peptidases with a quite unique post-proline cleavage specificity. Known inhibitors contain a limited number of molecular anchors occupying the small prototypical S1 pocket. A virtual screening approach for such S1-binding fragments was carried out using FlexX docking to evaluate its potential to confirm known and find novel compounds. Several low molecular weight inhibitors exhibiting activities in the micromolar range could be identified as starting points for structure-based design.

Custom chemical microarray production and affinity fingerprinting for the S1 pocket of factor VIIa

The goal of this study was to explore the applicability of surface plasmon resonance (SPR)-based fragment screening to identify compounds that bind to factor VIIa (FVIIa). Based on pharmacophore models virtual screening approaches, we selected fragments anticipated to have a reasonable chance of binding to the S1-binding pocket of FVIIa and immobilized these compounds on microarrays. In affinity fingerprinting experiments, a number of compounds were identified to be specifically interacting with FVIIa and shown to fall into four structural classes. The results demonstrate that the chemical microarray technology platform using SPR detection generates unique chemobiological information that is useful for de novo discovery and lead development and allows the detection of weak interactions with ligands of low molecular weight.

Long-term results of hysteroscopic myomectomy for abnormal uterine bleeding

OBJECTIVE

To analyze the efficacy of transcervical resection of submucous myomas and to identify prognostic factors for long-term results.

METHODS

Two-hundred eighty-five women were treated with transcervical resection of submucous myomas without endometrial ablation. In case of incomplete resection a repeat procedure was offered. Long-term follow-up was obtained. Recurrence was defined as the need for further surgery. The relation of several variables with the outcome was analyzed using Cox proportional hazard regression analysis.

RESULTS

Seventeen cases (6%) were lost to follow-up. The median follow-up was 46 months (range 1-104 months); for cases without recurrence median follow-up was 42 months (range 16-104 months). Forty-one (14.5%) patients had repeat surgery. An independent prognostic value of uterine size (P < .001) and number of submucous myomas (P < .001) for recurrence was noted. Twenty of 41 patients who had repeat surgery subsequently had a hysterectomy. None of the variables investigated predicted the need for hysterectomy. The surgery-free percentage of 165 patients with normal sized uteri and not more than two myomas was 94.3% (standard error +/- 1.8%) at 2 years and 90.3% (+/- 3.0%) at 5 years.

CONCLUSION

Transcervical resection of submucous myomas is a safe and effective treatment for patients with a normal sized uterus and not more than two myomas. It is an acceptable alternative for selected other patients. The need for a combined endometrial ablation is questionable. Transcervical resection of submucous myomas will give patients a high chance of averting further surgery and should modify the way patients are counseled.

Decreased release of histamine and sulfidoleukotrienes by human peripheral blood leukocytes after wasp venom immunotherapy is partially due to induction of IL-10 and IFN-gamma production of T cells

BACKGROUND

Recent studies provide evidence that venom immunotherapy (VIT) alters the pattern of cytokine production by inducing an allergen-specific T-cell shift in cytokine expression from TH2 (IL-4, IL-5) to TH1 (IFN-gamma) cytokines and also inducing the production of IL-10.

OBJECTIVE

This study was carried out to analyze whether these changes in cytokine production of T cells already observed 1 week after the initiation of VIT in subjects with wasp venom allergy also influence the reactivity of effector cells, such as mast cells and basophils.

METHODS

All subjects included in this study had a history of severe systemic allergic reactions to wasp stings and positive skin test responses with venom and venom-specific IgE in the sera. Peripheral blood leukocytes were isolated before and after the initiation of VIT (rush therapy reaching a maintenance dose of 100 microg venom injected subcutaneously within 1 week) and preincubated with or without addition of IL-10, IFN-gamma, IL-10 + IFN-gamma, anti-IL-10, or anti-IFN-gamma. After stimulation with wasp venom, histamine and sulfidoleukotriene release were assessed by ELISA and compared with spontaneous release and total histamine content.

RESULTS

After the induction of VIT, venom-induced absolute and relative histamine and sulfidoleukotriene release were reduced. This was at least partially due to the induction of IFN-gamma and IL-10 production, because (1) neutralization of IL-10 and IFN-gamma by mAbs partially restored the release after the initiation of VIT and (2) the addition of exogenous IFN-gamma and IL-10 caused a statistically significant diminution of the venom-induced histamine and sulfidoleukotriene release before VIT. Depletion of CD2(+) T cells also restored the releasability after VIT.

CONCLUSION

These data indicate that T cells (producing IL-10 and IFN-gamma after VIT) play a key role for the inhibition of histamine and sulfidoleukotriene release of effector cells.

Insect venom immunotherapy induces interleukin-10 production and a Th2-to-Th1 shift, and changes surface marker expression in venom-allergic subjects

The current study was carried out to elucidate the immunoregulatory changes induced by venom immunotherapy (VIT) in bee or wasp allergic subjects. All subjects included in this study had a history of severe systemic allergic reactions to stings of the respective insect as well as positive skin tests with the respective venom or venom-specific IgE in the sera. Parameters assessed in peripheral blood mononuclear cells (PBMC) before and after initiation of VIT (rush therapy reaching a maintenance dose of 100 micrograms venom injected subcutaneously within 1 week) were expression of CD3, CD4, CD8, CD45RA, CD45RO, interleukin (IL)-2 receptor (R) alpha, IL-4R, IL-12R, Fc epsilon RII, CD40, and CD40 ligand (CD40L), cells producing interferon (IFN)-gamma and IL-10 after stimulation with phorbol 12-myristate 13-acetate + ionomycin in the presence of monensin measured by flow cytometry; secretion of IFN-gamma, IL-4, and IL-10 measured by ELISA (IFN-gamma and IL-10 were additionally measured by PCR), and proliferation after stimulation with the respective venom. Significant decreases were observed after VIT for proliferative response to venom and venom + IL-4, IL-4 secretion, Fc epsilon RII, CD40, and CD40L expression. Significant increases were observed after VIT for IFN-gamma concerning the amount secreted and the number of producing cells, and IL-10, IL-10 was mainly produced by CD4+ cells that were negative for IFN-gamma, but some double-positive (IL-10 and IFN-gamma) cells were always detected. Addition of blocking anti-IL-10 antibodies, but not isotype control antibodies, prevented down-regulation of proliferation (but not IL-4 secretion) and further enhanced IFN-gamma secretion after VIT. These data indicate that in insect venom allergic subjects, VIT not only induces a rapid shift in cytokine expression from Th2 to Th1 cytokines, but also leads to induction of the immunosuppressive cytokine IL-10, which may be important for the limitation of potentially harmful allergen-specific Th1 responses. The described changes in cytokine expression may be responsible for subsequent increases in allergen-specific IgG and decreases in IgE production, as well as suppressive activity observed in earlier studies.

Towards quantitative CP-MAS NMR

Many of the combined cross polarization-magic angle spinning (CP-MAS) experiments that have been developed over the past ten years for structural studies of chemical and biological systems rely on the measurement of quantitative signal intensities. However, one of the drawbacks of the CP technique is that the efficiency of polarization transfer depends on the strength of the heteronuclear dipolar interaction which is generally different for different chemical groups. In this paper, we propose the use of a linear ramp of CP amplitudes in combination with high speed MAS to improve signal quantitation. The linear ramp is centered on one of the sidebands of the Hartmann-Hahn matching profile and the contact time is chosen to maximize the total signal in the CP-MAS spectrum. The approach is illustrated on N-t-Boc-alanine whose six carbons exhibit a range of heteronuclear dipolar couplings and molecular motions.

Nitric oxide production is increased in patients after burn injury

OBJECTIVE

Human burn injury is associated with an inflammatory response and related hyperdynamic cardiovascular profile. Increased production of nitric oxide (NO), a potent endogenous vasodilator, has been reported in patients with inflammatory states, including sepsis, but not after trauma other than burns. We studied whether plasma levels of the stable byproducts of NO, nitrite (NO2-) and nitrate (NO3-), are increased in burn patients.

DESIGN

Prospective controlled study.

PATIENTS AND METHODS

In consecutive patients admitted to the intensive care unit of the burn center at the Queen Astrid Military Hospital in Brussels, plasma was drawn daily from day 1 to day 5 postadmission for determination of NO2-/NO3- levels (Griess' reaction). In a control group of nonseptic inpatients from the department of neurology in Erasme University Hospital who were matched for nutrition (30 to 40 kcal/kg/day of a standard enteral solution), plasma was drawn once for NO2-/NO3- determination.

MEASUREMENTS AND MAIN RESULTS

The burn group included 16 patients (age 35 +/- 18 years, total burn surface area (TBSA) 37 +/- 19%) and the control group included six patients (age 64 +/- 18 years). For each comparison between the groups, NO2-/NO3- plasma levels were higher in those patients with burns than in the control group. In the burn group, there was no correlation between NO2-/NO3- plasma levels and TBSA, age, TBSA x age, blood pressure or time. However, in a subgroup of five burned patients who became septic during the study period, NO2-/NO3- plasma levels were slightly higher than in the non-infected patients (177 +/- 131 vs. 83 +/- 48 micromoles/L, NS).

CONCLUSION

Human burn injury is associated with an increase in NO production. In this small-size study, NO production was not proportional to burn area, and seemed to be further enhanced in septic patients.

Solid-state 13C-NMR of [(3-13C)Pro]bacteriorhodopsin and [(4-13C)Pro]bacteriorhodopsin: evidence for a flexible segment of the C-terminal tail

The configuration of an Xaa-Pro bond can be determined by solid-state magic-angle-sample-spinning (MASS)-13C-NMR spectroscopy since the chemical shifts of C beta and Cgamma of the proline ring are sensitive to the isomerization state of the preceding peptide bond. (3-13C)Pro and (4-13C)Pro have been chemically synthesized; the former by means of an asymmetric synthesis. The 13C-labeled Pro residues were biosynthetically incorporated into bacteriorhodopsin with a yield of 80%. The solid-state-MASS-13C-NMR spectra of [(3-13C)Pro]bacteriorhodopsin and [(4-13C)Pro]bacteriorhodopsin revealed isotropic chemical shifts at 29.8 ppm and 25.5 ppm, respectively. From the chemical-shift values we conclude that all Xaa Pro peptide bonds are in the trans configuration confirming previous results from solution-NMR studies on solubilized bacteriorhodopsin in organic solvents [Deber, M.C., Sorrell, B.J. & Xu, G.Y. (1990) Biochem. Biophys. Res. Commun. 172, 862-869]. Inversion-recovery experiments could differentiate between three classes of Pro residues distinguished by their relaxation time t1. Tentatively, these three distinct groups of Pro residues could be assigned to the helical, the loop, and the C-terminal parts of the protein. The resonances of the two C-terminal Pro could be identified by removing the C-terminus by proteolysis. Although they are separated by only one Glu they occupy different chemical environments and possess different flexibilities. These results indicate that the first part of the C-terminal tail is constrained. Pro238 marks the position where the tail becomes freely mobile. It is proposed that the C-terminus is fixed to the membrane via salt bridges between divalent cations and negative charges of the C-terminus as well as interhelical loops.

Effects of methylene blue on oxygen availability and regional blood flow during endotoxic shock

OBJECTIVE

We hypothesized that methylene blue, by inhibiting the activation of soluble guanylate cyclase mediated by nitric oxide, may reverse systemic hypotension, enhance myocardial function, and improve peripheral distribution of blood flow during endotoxic shock.

DESIGN

Randomized, controlled, acute intervention study.

SETTING

University intensive care laboratory.

SUBJECTS

Twenty-one healthy, anesthetized, mongrel dogs, weighing 26 +/- 4 kg.

INTERVENTIONS

Groups 1 (n = 7) and 2 (n = 7) received endotoxin (2 mg/kg iv) alone combined with increasing doses of 2.5, 5, 10, and 20 mg/kg iv of methylene blue. Each dose was administrated for 30 mins with a free interval of 30 mins. Group 3 (n = 7) served as a control group, receiving the same doses of methylene blue in the absence of endotoxin. All animals were given normal saline to keep cardiac filling pressures constant. Blood flow probes were placed around the superior mesenteric, renal, and femoral arteries to measure regional blood flow by ultrasonic technique. Data were collected every 30 mins during the study.

MEASUREMENTS AND MAIN RESULTS

After endotoxemia, methylene blue increased systemic and pulmonary arterial pressure and vascular resistances in a dose-dependent manner up to 10 mg/kg, but had no effect on cardiac index. At the highest dose, methylene blue decreased arterial pressure and systemic vascular resistance. At doses of methylene blue of < or = 10 mg/kg, mesenteric and femoral blood artery flow increased. At the highest dose of 20 mg/kg, femoral artery blood flow further increased, but mesenteric blood flow decreased. Renal artery blood flow was unaffected by methylene blue. In the absence of endotoxin, methylene blue at doses of 2.5 or 5 mg/kg did not alter mean arterial pressure, but reduced cardiac index, indicating an increase in systemic vascular resistance. In contrast, the higher doses of 10 or 20 mg/kg of methylene blue decreased mean arterial pressure and systemic vascular resistance. However, pulmonary arterial pressure and pulmonary vascular resistance increased in a dose-dependent manner. Mesenteric and renal artery blood flow decreased but femoral blood flow increased. As in the presence of endotoxin, methylene blue induced dose-related increases in oxygen uptake and oxygen extraction ratio, but did not alter oxygen delivery. Methylene blue largely attenuated the endotoxin-induced increase in plasma nitrite concentrations.

CONCLUSIONS

Low and moderate doses of methylene blue can significantly increase arterial blood pressure but not cardiac index during endotoxic shock. Methylene blue infusion may selectively increase mesenteric blood flow. High doses of methylene blue can worsen systemic hypotension, myocardial depression, and pulmonary hypertension after endotoxemia.

Tirilazad mesylate (U-74006F) inhibits effects of endotoxin in dogs

The present study explored the effects of a potent antioxidant, the 21-aminosteroid U-74006F, on the systemic and regional hemodynamics and the oxygen extraction capabilities during endotoxic shock. Twenty-four anesthetized dogs were randomized into three groups. Group 1 (n = 8) served as control. Group 2 (n = 8) and group 3 (n = 8) received 2 mg/kg iv of Escherichia coli endotoxin, followed 30 min later by saline infusion. Group 3 was given U-74006F as an intravenous bolus of 80 micrograms/kg followed by an infusion of 10 micrograms.kg-1.min-1, and group 2 received an equivalent volume of vehicle. Tamponade was induced 30 min later to study the oxygen extraction capabilities of the animals. Compared with the endotoxin-alone group, the U-74006F-treated dogs maintained higher mean arterial pressure, cardiac index, stroke volume index, and left ventricular stroke work index and lower pulmonary vascular resistance. They also showed a higher fractional blood flow to mesenteric and renal beds. Endotoxin administration increased whole body critical oxygen delivery (DO2crit) from 7.7 +/- 2.4 to 12.0 +/- 1.9 ml.kg-1.min-1 (P < 0.05), but U-74006F decreased DO2crit to 7.8 +/- 2.0 ml.kg-1.min-1 (P < 0.05 vs. endotoxin alone). Endotoxin decreased critical oxygen extraction ratio (O2ERcrit) from 75.0 +/- 12.7 to 44.3 +/- 8.7% (P < 0.05), but U-74006F increased O2ERcrit to 64.1 +/- 11.2% (P < 0.05 vs. endotoxin alone). U-74006F also decreased endotoxin-induced elevation of mesenteric and renal DO2crit and markedly increased regional O2ERcrit. Systemic and regional blood lactate concentrations were lower in the U-74006F-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon-gamma-activated immature macrophages exhibit a high Trypanosoma cruzi infection rate associated with a low production of both nitric oxide and tumor necrosis factor-alpha

Murine peritoneal macrophages (MPM) can be subdivided into two subpopulations of mature and immature macrophages. In contrast to mature macrophages, immature ones were highly susceptible to Trypanosoma cruzi infection. This highly susceptibility was associated with a low production of alpha 2-macroglobulin. Interferon-gamma (IFN-gamma)-activated immature macrophages also exhibited a higher infection rate than did IFN-gamma-activated mature ones. This higher rate of infection was associated with a low production of both nitric oxide (N = O) and tumor necrosis factor-alpha (TNF-alpha). In contrast, mature MPM showed a lower rate of infection and produced higher levels of N = O and TFN-alpha. Taken together, these results show a clear-cut difference in the course of T. cruzi infection in relation to the macrophage maturation state.

Trypanosoma cruzi upregulates nitric oxide release by IFN-gamma-preactivated macrophages, limiting cell infection independently of the respiratory burst

The relationship between nitric oxide (N = O) produced by mouse peritoneal macrophages (MPM) and Trypanosoma cruzi infection is still poorly understood. The conditions of MPM activation by gamma-interferon (IFN-gamma) to trigger a N = O-dependent trypanocidal activity, as well as the effect of parasite infection or of reactive oxygen species (ROS) inhibitors on the N = O release were studied. T. cruzi infection occurring after a previous 24 h MPM activation induced an enhancement of nitrite levels (the stable degradation product of N = O) in cell supernatants; both the percentage of infected MPM and the number of amastigotes per infected cell were decreased in comparison to infected but non-activated MPM. Addition of superoxide dismutase or catalase to non-infected but activated MPM increased the nitrite levels; these were not detectable when L-arginine inhibitors were added together with ROS inhibitors. The latter had no effect on infection nor on nitrite levels when infection occurred after pre-activation, and induced only a weak nitrite release when infection took place before MPM activation. Altogether, these results support the involvement of N = O in the inhibition of T. cruzi infection by IFN-gamma-preactivated macrophages, together with the upregulation of N = O release by T. cruzi infection independently of the respiratory burst.

Asp85 is the only internal aspartic acid that gets protonated in the M intermediate and the purple-to-blue transition of bacteriorhodopsin. A solid-state 13C CP-MAS NMR investigation

High-resolution solid-state 13C NMR spectra of the ground state and M intermediate of the bacteriorhodopsin mutant D96N with the isotope label at [4-13C]Asp and [11-13C]Trp were recorded. The NMR spectra show that Asp85 is protonated in the M intermediate. The environment of Asp85 is quite hydrophobic. On the other hand, Asp212 remains deprotonated and a slight shift to lower field indicates a more hydrophilic environment. Asp85 also protonates in the purple-to-blue transition of bacteriorhodopsin in the deionized membrane, where it experiences a similar environment to M. The shift of Trp resonances in M reflect a conformational change of the protein in forming the M intermediate.

High-resolution solid state 13C NMR of bacteriorhodopsin: characterization of [4-13C]Asp resonances

Solid state 13C nuclear magnetic resonance measurements of bacteriorhodopsin labeled with [4-13C]Asp show that resonances of single amino acids can be resolved. In order to assign and characterize the resonances of specific Asp residues, three different approaches were used. (1) Determination of the chemical shift anisotropy from side-band intensities provides information about the protonation state of Asp residues. (2) Relaxation studies and T1 filtering allow one to discriminate between resonances with different mobility. (3) A comparison of the spectra of light- and dark-adapted bacteriorhodopsin provides evidence for resonances from aspartic acid residues in close neighborhood of the chromophore. In agreement with other investigations, four resonances are assigned to internal residues. Two of them are protonated in the ground state up to pH 10 (Asp96 and Asp115). All other detected resonances, including Asp85 and Asp212, are due to deprotonated aspartic acid. Two lines due to the two internal deprotonated groups change upon dark and light adaptation, whereas the protonated Asp residues are unaffected.

[Emergency intubation and ventilation therapy in severe bronchial asthma]

37 patients were treated with emergency intubation because of severe asthma bronchiale. In 30 patients the usual bronchospasmolytic therapy was ineffective, 12 patients were under permanent treatment. Halothane produced immediate and unequivocal improvement of respiratory global insufficiency and resolution of bronchospasm in 8 out of 13 patients, ketamine in 6 of 18 and a combination of both drugs in 4 of 9 patients. Both drugs are an efficient complement to conventional emergency treatment. A step-by-step schema for anaesthesia in severe asthma bronchiale requiring intubation is presented.

High resolution 13C-solid state NMR of bacteriorhodopsin: assignment of specific aspartic acids and structural implications of single site mutations

Three mutant strains of Halobacterium sp. GRB with the site of mutation in the bacterioopsin gene (PM 326: Asp96----Asn; PM 374: Asp96----Gly; PM 384: Asp85----Glu) were grown in a synthetic medium containing (4-13C)-Asp. The mutant bacteriorhodopsins labeled with (4-13C)-Asp (37%-45%), and owing to the metabolism of Halobacteria also with (11-13C)-Trp (50%-100%), were isolated as purple membranes and 13C Solid State Magic Angle Sample Spinning (MASS) Nuclear Magnetic Resonance (NMR) spectra of the samples were taken. The Asp96 mutants lacked the signal at 171.3 ppm which was previously assigned to a protonated internal Asp (Engelhard et al. 1989a). This observation supports the conclusion that Asp96 is protonated in the ground state. PM 384 (Asp85----Glu) has an absorption maximum at 610 nm. It can be converted into a purple form (lambda max = 540 nm) by treatment with a detergent (CHAPSO). The NMR-spectra of these two species differ from each other and from the wild type. The intensity of the resonance at 173 ppm in the wild type spectrum is reduced in both forms of the mutant protein. It is probable that this signal is caused by Asp85. The amino acid changes result not only in a perturbation of their direct environment but also effects on Trp residues and the chromophore protein interaction can be observed.

Magic angle sample spinning 13C nuclear magnetic resonance of isotopically labeled bacteriorhodopsin

Bacteriorhodopsin (bR), the light-driven proton pump protein from Halobacterium halobium, was biosynthetically labeled with [4-13C]Asp. The incorporation yield was 48%. The magic angle sample spinning (MASS) 13C nuclear magnetic resonance (NMR) spectrum of this sample revealed six different peaks superimposed on a broad band of naturally abundant peptide-bond 13C. Two of the six carbonyl signals can be attributed to internal-protonated Asp carboxyl groups, one of which might be Asp115. An additional resonance at 110 ppm can be associated with the C-11 carbon of Trp, indicating an unusual biosynthetic pathway of this amino acid in Halobacterium halobium. Similar measurements performed on papain-treated purple membrane which lacks the C-terminal tail display two new intense signals at 178 and 178.9 ppm. If the same spectrum is taken without cross-polarization, these signals do not decrease or disappear. On the basis of their intensities and their chemical shifts, one can assign in addition to the C-terminal Asp four Asp residues facing the cytoplasmic phase. In native bR, at least two of these form a salt-bridge-like bond which also might include the C-terminal tail. These experiments not only provide data about the chemical environment of the Asp residues within the hydrophobic core of bacteriorhodopsin but also yield information about the interactions between surface components.

Calmodulin antagonism: a pharmacological approach for the inhibition of mediator release from mast cells

Several Ca2+ antagonists with either Ca2+-entry blocking or calmodulin (CaM) antagonistic properties and antiallergic drugs were investigated for their effects on mediator release from mast cells induced by different secretagogues (compound 48/80, concanavalin A, antigen-IgE and Ca2+ ionophore A23187) and for their ability to inhibit the function of CaM or phospholipid/Ca2+-dependent protein kinase (C-kinase). The effects of the different agents--with the only exception of cromolyn sodium--on histamine release elicited by compound 48/80 correlated well with their actions on two CaM-dependent enzymes whereas the activity of C-kinase was far less altered, or not altered at all. CaM antagonism of cloxacepride, picumast, oxatomide, fendiline and bepridil correlated not only with the inhibition of exocytosis evoked by compound 48/80 but also with that induced by A23187, concanavalin A and antigen-IgE. This indicates an action of these substances distal to the generation of the Ca2+ signal since the various secretagogues elevate the intracellular Ca2+ concentration by different mechanisms. However, prenylamine and thioridazine inhibited concanavalin A- and antigen-IgE-induced mediator release more potently and more effectively than that elicited by compound 48/80 or A23187. Therefore inhibition of allergic histamine release by these drugs may in part be dependent on an impairment of the Ca2+ signal. Since for each of two agents inhibition of histamine release (evoked by different releasers) parallels that of serotonin release it may be concluded that these mediators are secreted via the same mechanism. The results obtained with agents exhibiting different pharmacological properties but which share one common property, namely antagonism of CaM, strengthen the view that CaM is involved in exocytosis of mediators from mast cells.

Effect of etofylline clofibrate on experimental thrombus formation and prostacyclin activation

1-(7-Theophyllinyl)-2-ethyl-[2-(p-chlorophenoxy)-isobutyrate] (etofylline clofibrate, theofibrate, Duolip) was shown to possess substantial thrombus disaggregating activity in the microcirculation of the hamster cheek pouch following minor vascular damage by electrical stimulation. At 12 mg/kg p.o. the moderate effect of a single dose (12% reduction in disaggregation time) increased to a maximum reduction of 31 and 43% following 5 and 7 consecutive daily applications, respectively. Etofylline clofibrate was more active than other drugs already tested in this test system, but less than the prostaglandins PGE1 and PGI2. The antithrombotic efficacy found in both in vivo tests, thrombus formation and disaggregation, suggests as mode of action of etofylline clofibrate an agonistic interaction with intimal PGI2. This could be by enhancement of its production or by a synergistic interaction with this prostanoid, rather than inhibition of thromboxane A2 synthetase.

Failure of ibuprofen in treatment of herpes genitalis

Motrin (ibuprofen), a potent inhibitor of prostaglandin synthetase, was tested in women and men for treatment of recurrences of genital herpes. In a double-blind trial, no statistically significant differences were observed between treated and placebo groups in any of the measured parameters.

Blood transfusion requirements in coronary artery surgery with and without the activated clotting time (ACT) technique

Control of anticoagulation during cardiopulmonary bypass (CPB) with the automated activated whole blood clotting time (ACT) and reversal of heparin after CPB using a computerized ACT dose-response curve method resulted in significant reductions of blood transfusion requirements, surgical time, and protamine doses in 150 patients undergoing coronary artery bypass grafting procedures (ACT group) as compared to 200 patients for whom a standard fixed dose protocol for heparin and protamine was used (control patients). Mean transfusion requirements were 1,938 +/- 60 SEM ml whole blood and 853 +/- 48.3 SEM ml red blood cells for control patients and 1,397 +/- 59 SEM ml whole blood (P less than 0.001) and 695 +/- 34 SEM ml red blood cells (P less than 0.01) in the ACT group. ACT group patients also required less protamine with 26.2 +/- 0.60 SEM ml Protamine 1,000 (Roche) as compared to 33.9 +/- 0.49 SEM ml for control patients (P less than 0.001) but more heparin with 31,440 +/- 783 SEM I.U. versus 26,760 +/- 263 SEM I.U. (P less than 0.001). Surgical time decreased from 321 +/- 5.5 SEM min for control patients to 289 +/- 5.4 SEM min for ACT group patients (P less than 0.001).

Similarities between human and rat leukocyte elastase and cathepsin G

Rat is a likely test animal for determining the efficacy of proteinase inhibitor drugs directed toward human leukocyte elastase and cathepsin G. We therefore sought to assess and compare relevant properties of both human and rat leukocyte elastase and cathepsin G. Some differences between the pairs of proteinases from the two species were found, however both pairs of enzymes displayed comparable specificity toward various natural (plant and animal) proteinase inhibitors and also toward specific peptide substrates and a serine proteinase-specific reagent. Such overlapping specificity implies similarity of reactive center topography and sequence homology around the extended substrate/inhibitor binding regions of these proteinases. This apparent homology leads us to conclude that a pharmacologically effective inhibitor of leukocyte proteinases in the rat would probably also be effective in man.

Methods of introducing nasoenteric feeding. A prospective randomized study

In 50 patients requiring enteral nutritional support, a nasogastric feeding regimen with an isotonic, polymeric solution was introduced either by the slow, conventional four-day method or by a more rapid one. The incidences of symptoms associated with either introduction protocol were compared. As many as 82% of patients showed no sign of intolerance, whatever the method used. Of the remainder, four developed symptoms that might have been associated with the treatment. Only one of these patients had been subjected to the fast introduction protocol. It is concluded that undiluted isotonic lactose-free nasoenteric solutions can be safely introduced rapidly to meet energy requirements earlier.

[An electronic communication aid with a large keyboard for artificial respiration patients in the intensive care unit]

An increasing number of patients under mechanical ventilation in ICUs suffers from being cut off from normal communication. The existing communication facilities, such as letter-boards, magnetic letters, pictograms, Yes-no-signals and attempts at written communication are very often insufficient or not to be mastered by the weakened ICU respirator patient. We, therefore, present an electronic communicator consisting of a keyboard with big push-buttons and an illuminated running-letter display. Up to one page of text can be stored in memory and recalled later as running or printed text. Initial experiences with the electronic communicator show that even weakened respirator patients with diminished sensomotoric abilities successfully manage to communicate with the staff.