[1,2,4]Triazolo[3,4-b]benzothiazole Scaffold as Versatile Nicotinamide Mimic Allowing Nanomolar Inhibition of Different PARP Enzymes

We report [1,2,4]triazolo[3,4-b]benzothiazole (TBT) as a new inhibitor scaffold, which competes with nicotinamide in the binding pocket of human poly- and mono-ADP-ribosylating enzymes. The binding mode was studied through analogues and cocrystal structures with TNKS2, PARP2, PARP14, and PARP15. Based on the substitution pattern, we were able to identify 3-amino derivatives 21 (OUL243) and 27 (OUL232) as inhibitors of mono-ARTs PARP7, PARP10, PARP11, PARP12, PARP14, and PARP15 at nM potencies, with 27 being the most potent PARP10 inhibitor described to date (IC₅₀ of 7.8 nM) and the first PARP12 inhibitor ever reported. On the contrary, hydroxy derivative 16 (OUL245) inhibits poly-ARTs with a selectivity toward PARP2. The scaffold does not possess inherent cell toxicity, and the inhibitors can enter cells and engage with the target protein. This, together with favorable ADME properties, demonstrates the potential of TBT scaffold for future drug development efforts toward selective inhibitors against specific enzymes.

ADP-ribosyltransferases, an update on function and nomenclature

ADP-ribosylation, a modification of proteins, nucleic acids, and metabolites, confers broad functions, including roles in stress responses elicited, for example, by DNA damage and viral infection and is involved in intra- and extracellular signaling, chromatin and transcriptional regulation, protein biosynthesis, and cell death. ADP-ribosylation is catalyzed by ADP-ribosyltransferases (ARTs), which transfer ADP-ribose from NAD+ onto substrates. The modification, which occurs as mono- or poly-ADP-ribosylation, is reversible due to the action of different ADP-ribosylhydrolases. Importantly, inhibitors of ARTs are approved or are being developed for clinical use. Moreover, ADP-ribosylhydrolases are being assessed as therapeutic targets, foremost as antiviral drugs and for oncological indications. Due to the development of novel reagents and major technological advances that allow the study of ADP-ribosylation in unprecedented detail, an increasing number of cellular processes and pathways are being identified that are regulated by ADP-ribosylation. In addition, characterization of biochemical and structural aspects of the ARTs and their catalytic activities have expanded our understanding of this protein family. This increased knowledge requires that a common nomenclature be used to describe the relevant enzymes. Therefore, in this viewpoint, we propose an updated and broadly supported nomenclature for mammalian ARTs that will facilitate future discussions when addressing the biochemistry and biology of ADP-ribosylation. This is combined with a brief description of the main functions of mammalian ARTs to illustrate the increasing diversity of mono- and poly-ADP-ribose mediated cellular processes.

Azide- and diazirine-modified membrane lipids: Physicochemistry and applicability to study peptide/lipid interactions via cross-linking/mass spectrometry

Although the incorporation of photo-activatable lipids into membranes potentially opens new avenues for studying interactions with peptides and proteins, the question of whether azide- or diazirine-modified lipids are suitable for such studies remains controversial. We have recently shown that diazirine-modified lipids can indeed form cross-links to membrane peptides after UV activation and that these cross-links can be precisely determined in their position by mass spectrometry (MS). However, we also observed an unexpected backfolding of the lipid's diazirine-containing stearoyl chain to the membrane interface challenging the potential application of this modified lipid for future cross-linking (XL)-MS studies of protein/lipid interactions. In this work, we compared an azide- (AzidoPC) and a diazirine-modified (DiazPC) membrane lipid regarding their self-assembly properties, their mixing behavior with saturated bilayer-forming phospholipids, and their reactivity upon UV activation using differential scanning calorimetry (DSC), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and MS. Mixtures of both modified lipids with DMPC were further used for photo-chemically induced XL experiments with a transmembrane model peptide (KLAW23) to elucidate similarities and differences between the azide and the diazirine moiety. We showed that both photo-reactive lipids can be used to study lipid/peptide and lipid/protein interactions. The AzidoPC proved easier to handle, whereas the DiazPC had fewer degradation products and a higher cross-linking yield. However, the problem of backfolding occurs in both lipids; thus, it seems to be a general phenomenon.

Quantitative analysis of soft tissue sagging after lateral midface fractures: A 10-year retrospective study

BACKGROUND

Lateral midface fractures occasionally require open reduction and internal fixation to restore function and facial symmetry. However, some patients retain facial asymmetry despite undergoing surgery due to hard tissue displacement or soft tissue sagging. This study aimed to determine the influence of soft tissue sagging on the postoperative facial symmetry.

METHODS

We examined the medical records of 590 patients who underwent planned plate removal after lateral midface or zygomatic bone fractures. After applying the inclusion and exclusion criteria, we analyzed 106 cases of lateral midface fractures for hard tissue displacement and soft tissue sagging using pre- and postoperative radiological imaging and postoperative face scanning.

RESULTS

We observed significantly larger soft tissue sagging (p < 0.001) and hard tissue displacement (p = 0.006) on the fractured side than on the non-fractured side. There was no correlation between differences in the soft tissue sagging and those in the hard tissue displacement (|rho|=0). Linear regression analysis showed no statistical influence of sex or age group on the soft tissue sagging and hard tissue displacement.

CONCLUSION

Therefore, we recommend treating soft tissue sagging as a discrete aspect of midfacial fracture treatment to achieve optimal postoperative facial symmetry. From a clinical perspective, we recommend better soft tissue management during open fracture treatment than focusing mainly on the reduction of bony hard tissues.

Intracellular mono-ADP-ribosyltransferases at the host-virus interphase

The innate immune system, the primary defense mechanism of higher organisms against pathogens including viruses, senses pathogen-associated molecular patterns (PAMPs). In response to PAMPs, interferons (IFNs) are produced, allowing the host to react swiftly to viral infection. In turn the expression of IFN-stimulated genes (ISGs) is induced. Their products disseminate the antiviral response. Among the ISGs conserved in many species are those encoding mono-ADP-ribosyltransferases (mono-ARTs). This prompts the question whether, and if so how, mono-ADP-ribosylation affects viral propagation. Emerging evidence demonstrates that some mono-ADP-ribosyltransferases function as PAMP receptors and modify both host and viral proteins relevant for viral replication. Support for mono-ADP-ribosylation in virus–host interaction stems from the findings that some viruses encode mono-ADP-ribosylhydrolases, which antagonize cellular mono-ARTs. We summarize and discuss the evidence linking mono-ADP-ribosylation and the enzymes relevant to catalyze this reversible modification with the innate immune response as part of the arms race between host and viruses.

Cleft lip and palate: the psychological burden of affected parents during the first three years of their children's lives

The surgical treatment of cleft lip and palate (CLP) has been well described in the literature. Nevertheless, little is known about the psychological burden of affected parents. The aim of this study was to investigate the psychological burden in parents of children with CLP within the first 3 years of the children's lives. A standardized questionnaire (Parenting Stress Index, PSI) was administered to 33 parents of children with CLP to evaluate their psychological burden. The corresponding interview was conducted independent of any operative procedure during the yearly routine CLP consultation. Each participant's stress profile was assessed and compared with the average values of parents with non-cleft children. Psychological stress was substantially increased in all participants when compared to the parents of healthy children. This result was highly significant (P < 0.001). Parent depression (P < 0.001) and child-related requirements (P < 0.001) were the most critical subscales in the stress profile. Overall, the child-related burden was greater than the parent-related burden. These results indicate that parents of children with CLP have a higher level of psychological stress than parents of non-cleft children. This psychological stress might be reduced if addressed by specialist clinical psychologists in cleft-treating centres.

Paediatric gingival extra-axial chordoma: an extremely rare entity

Extra-axial chordomas are rare malignant tumours. As a subcategory of axial chordomas, these tumours arise outside the axial skeleton. This report describes the case of a 13-year-old male patient with a gingival mass in the left upper jaw, who was referred to Hannover Medical School with a preliminary diagnosis of a calcifying epithelial odontogenic tumour (CEOT). Pathological examination of the enucleated tumour led to the final diagnosis of a chordoma. Thereafter, a stepwise radical resection was performed with the aim of complete resection of the tumour with wide safety margins. The main tumour mass was found to be located on the maxillary gingiva, with focal infiltration into the maxillary bone. Following resection, reconstruction was performed with a free latissimus dorsi flap. Follow-up after 1 year revealed no signs of recurrence or metastasis. This case highlights that although extremely rare, extra-axial chordoma may occur at sites distant from the midline and as such must be included in the differential diagnosis of bone and soft tissue tumours in the maxillofacial region.

A Diazirine-Modified Membrane Lipid to Study Peptide/Lipid Interactions - Chances and Challenges

Although incorporation of photo‐activatable lipids into membranes potentially opens up novel avenues for investigating interactions with proteins, the question of whether diazirine‐modified lipids are suitable for such studies, remains under debate. Focusing on the potential for studying lipid/peptide interactions by cross‐linking mass spectrometry (XL‐MS), we developed a diazirine‐modified lipid (DiazPC), and examined its behaviour in membranes incorporating the model α‐helical peptide LAVA20. We observed an unexpected backfolding of the diazirine‐containing stearoyl chain of the lipid. This surprising behaviour challenges the potential application of DiazPC for future XL‐MS studies of peptide and protein/lipid interactions. The observations made for DiazPC most likely represent a general phenomenon for any type of membrane lipids with a polar moiety incorporated into the alkyl chain. Our finding is therefore of importance for future protein/lipid interaction studies relying on modified lipid probes.

Evaluation of 3- and 4-Phenoxybenzamides as Selective Inhibitors of the Mono-ADP-Ribosyltransferase PARP10

Intracellular ADP-ribosyltransferases catalyze mono- and poly-ADP-ribosylation and affect a broad range of biological processes. The mono-ADP-ribosyltransferase PARP10 is involved in signaling and DNA repair. Previous studies identified OUL35 as a selective, cell permeable inhibitor of PARP10. We have further explored the chemical space of OUL35 by synthesizing and investigating structurally related analogs. Key synthetic steps were metal-catalyzed cross-couplings and functional group modifications. We identified 4-(4-cyanophenoxy)benzamide and 3-(4-carbamoylphenoxy)benzamide as PARP10 inhibitors with distinct selectivities. Both compounds were cell permeable and interfered with PARP10 toxicity. Moreover, both revealed some inhibition of PARP2 but not PARP1, unlike clinically used PARP inhibitors, which typically inhibit both enzymes. Using crystallography and molecular modeling the binding of the compounds to different ADP-ribosyltransferases was explored regarding selectivity. Together, these studies define additional compounds that interfere with PARP10 function and thus expand our repertoire of inhibitors to further optimize selectivity and potency.

The mono-ADP-ribosyltransferase ARTD10 regulates the voltage-gated K+ channel Kv1.1 through protein kinase C delta

Background

ADP-ribosylation is a ubiquitous post-translational modification that involves both mono- and poly-ADP-ribosylation. ARTD10, also known as PARP10, mediates mono-ADP-ribosylation (MARylation) of substrate proteins. A previous screen identified protein kinase C delta (PKCδ) as a potential ARTD10 substrate, among several other kinases. The voltage-gated K⁺ channel Kv1.1 constitutes one of the dominant Kv channels in neurons of the central nervous system and the inactivation properties of Kv1.1 are modulated by PKC. In this study, we addressed the role of ARTD10-PKCδ as a regulator of Kv1.1.

Results

We found that ARTD10 inhibited PKCδ, which increased Kv1.1 current amplitude and the proportion of the inactivating current component in HeLa cells, indicating that ARTD10 regulates Kv1.1 in living cells. An inhibitor of ARTD10, OUL35, significantly decreased peak amplitude together with the proportion of the inactivating current component of Kv1.1-containing channels in primary hippocampal neurons, demonstrating that the ARTD10-PKCδ signaling cascade regulates native Kv1.1. Moreover, we show that the pharmacological blockade of ARTD10 increases excitability of hippocampal neurons.

Conclusions

Our results, for the first time, suggest that MARylation by ARTD10 controls neuronal excitability.

Oral health-related quality of life in tumour patients treated with patient-specific dental implants

Dental rehabilitation after surgically acquired bone deficiency related to tumour treatment remains a challenge. The insertion of patient-specific implants geared to the contour of the remaining bone is a feasible method of supporting fixed or removable dentures. As oral health-related quality of life (OHRQoL) is of great interest in these cases, 12 individuals treated with patient-specific implants for severe bone deficiency were surveyed and their Oral Health Impact Profile (OHIP) scores after dental rehabilitation were evaluated. The OHIP-G53 questionnaire was used to measure overall treatment outcomes. The distribution of OHIP sum-scores for participants treated with patient-specific implants was almost homogeneous when compared to those cited in the literature for patients treated with conventional dental implants. OHIP items related to functional impairment and physical pain showed the highest scores (occurring occasionally), and financial loss related to treatment was frequently stated. Moreover, higher scores were detected in almost all OHIP dimensions for participants with patient-specific implant-supported removable dentures. Conversely, those treated with patient-specific dental implants and fixed dentures showed lower psychosocial impact scores and equal or superior OHRQoL. Hence, patient-specific dental implants, especially combined with fixed dentures, can lead to a positive OHRQoL in patients with severe bone deficiencies related to tumour therapy.

Systemic sclerostin antibody treatment increases osseointegration and biomechanical competence of zoledronic-acid-coated dental implants in a rat osteoporosis model

Osseointegration of dental implants can be promoted by implant-surface modifications using bisphosphonate coatings. In addition, it is of clinical interest to promote peri-implant bone formation and to restore bony structure in low bone-mass patients. The present study evaluated a combination of an anti-resorptive zoledronic acid (ZOL) implant-coating and a systemically applied sclerostin antibody, a known bone anabolic treatment principle, versus sole sclerostin antibody treatment or ZOL implant-coating in a rat osteoporosis model. Uncoated reference surface implants or ZOL-coated implants (n = 64/group) were inserted into the proximal tibia of aged osteoporotic rats three months following ovariectomy. 32 animals of each group received once weekly sclerostin antibody therapy. Osseointegration was assessed 2 or 4 weeks post-implantation by ex vivo µCT, histology and biomechanical testing. Overall implant survival rate was 97 %. Histomorphology revealed pronounced bone formation along the entire implant length of ZOL-coated implants. At 4 weeks following implant insertion, bone-implant contact, cancellous bone mineral density and bone volume/tissue volume were significantly increased for the combination of ZOL and sclerostin antibody as compared to sclerostin antibody or ZOL implant-coating alone. Removal torque was also significantly increased in the combination therapy group relative to animals receiving only sclerostin antibody therapy or ZOL-coated implants. In an osteoporotic rat model, the combination of anti-resorptive ZOL implant-coating and systemically applied sclerostin antibody led to significantly increased peri-implant bone formation. Therefore, the combination of ZOL and the osteoanabolic sclerostin antibody was more effective than either agent alone.

Scapula pre-augmentation in sheep with polycaprolactone tricalcium phosphate scaffolds

A scapula free flap is a commonly used method to reconstruct intraoral defects of the mandible and maxilla. Despite its clear advantages, it shows some deficiencies concerning the amount and shape of the available bone, especially with respect to later implant placement. To overcome these limitations, we pre-augmented the scapula prior to a potential flap-raising procedure with polycaprolactone (PCL) tricalcium phosphate (TCP) scaffolds in a sheep model. In our study, the scapula angle was augmented with a block of PCL-TCP in three adult sheep. After 6 months, the amount of newly formed bone and scaffold degradation were evaluated using cone-beam computed tomography scans and histomorphometric analysis. All animals survived the study and showed no problems in the augmented regions. The scaffolds were attached firmly to the scapula and showed a bonelike consistency. A fair amount of the scaffold material was degraded and replaced by vital bone. Our method seems to be a valid approach to pre-augment the scapula in sheep. In further experiments, it will be interesting to determine whether it is possible to transplant a modified scapula flap to an intraoral defect site.

Chondroitin sulfate and sulfated hyaluronan-containing collagen coatings of titanium implants influence peri-implant bone formation in a minipig model

An improved osseous integration of dental implants in patients with lower bone quality is of particular interest. The aim of this study was to evaluate the effect of artificial extracellular matrix implant coatings on early bone formation. The coatings contained collagen (coll) in conjunction with either chondroitin sulfate (CS) or sulfated hyaluronan (sHya). Thirty-six screw-type, grit-blasted, and acid-etched titanium implants were inserted in the mandible of 6 minipigs. Three surface states were tested: (1) uncoated control (2) coll/CS (3) coll/sHya. After healing periods of 4 and 8 weeks, bone implant contact (BIC), bone volume density (BVD) as well as osteoid related parameters were measured. After 4 weeks, control implants showed a BIC of 44% which was comparable to coll/CS coated implants (48%) and significantly higher compared to coll/sHya coatings (37%, p = 0.012). This difference leveled out after 8 weeks. No significant differences could be detected for BVD values after 4 weeks and all surfaces showed reduced BVD values after 8 weeks. However, at that time, BVD around both, coll/CS (30%, p = 0.029), and coll/sHya (32%, p = 0.015), coatings was significantly higher compared to controls (22%). The osteoid implant contact (OIC) showed no significant differences after 4 weeks. After 8 weeks OIC for controls was comparable to coll/CS, the latter being significantly higher compared to coll/sHya (0.9% vs. 0.4%, p = 0.012). There were no significant differences in osteoid volume density. In summary, implant surface coatings by the chosen organic components of the extracellular matrix showed a certain potential to influence osseointegration in vivo.

Osseointegration of biochemically modified implants in an osteoporosis rodent model

The present study examined the impact of implant surface modifications on osseointegration in an osteoporotic rodent model. Sandblasted, acid-etched titanium implants were either used directly (control) or were further modified by surface conditioning with NaOH or by coating with one of the following active agents: collagen/chondroitin sulphate, simvastatin, or zoledronic acid. Control and modified implants were inserted into the proximal tibia of aged ovariectomised (OVX) osteoporotic rats (n = 32/group). In addition, aged oestrogen competent animals received either control or NaOH conditioned implants. Animals were sacrificed 2 and 4 weeks post-implantation. The excised tibiae were utilised for biomechanical and morphometric readouts (n = 8/group/readout). Biomechanical testing revealed at both time points dramatically reduced osseointegration in the tibia of oestrogen deprived osteoporotic animals compared to intact controls irrespective of NaOH exposure. Consistently, histomorphometric and microCT analyses demonstrated diminished bone-implant contact (BIC), peri-implant bone area (BA), bone volume/tissue volume (BV/TV) and bone-mineral density (BMD) in OVX animals. Surface coating with collagen/chondroitin sulphate had no detectable impact on osseointegration. Interestingly, statin coating resulted in a transient increase in BIC 2 weeks post-implantation; which, however, did not correspond to improvement of biomechanical readouts. Local exposure to zoledronic acid increased BIC, BA, BV/TV and BMD at 4 weeks. Yet this translated only into a non-significant improvement of biomechanical properties. In conclusion, this study presents a rodent model mimicking severely osteoporotic bone. Contrary to the other bioactive agents, locally released zoledronic acid had a positive impact on osseointegration albeit to a lesser extent than reported in less challenging models.

Thrombolysis for native arterial occlusions of the lower extremities: clinical outcome and cost

INTRODUCTION

Intra-arterial thrombolysis is commonly used as the initial treatment of acute or subacute lower extremity ischemia.

METHODS

To evaluate the efficacy and cost of thrombolysis, we retrospectively analyzed 100 consecutive cases (87 patients) in which intra-arterial lysis (urokinase) was used as the initial treatment for native arterial lower extremity occlusive disease. The mean age of patients was 67 years, 57% of the patients were male, and preexisting peripheral vascular disease was present in 74%. Presenting symptoms were limb-threatening ischemia (53%) and claudication (47%). Acute symptoms (< 2 weeks' duration) were present in 48%.

RESULTS

The 30-day morbidity rate was 31%, and four patients died. Complications were significant bleeding (23%), ischemic stroke (1%), and renal failure with (2%) and without (2%) dialysis. Concomitant angioplasty was performed in 63%. Complete or significant lysis as demonstrated with angiography was achieved in 75% of iliac, 58% of femoropopliteal, and 41% of crural vessels (P <.001). Within 30 days of lysis, 9% of patients underwent major amputation and 20% surgical revascularization (in 3 patients the extent of revascularization was lessened by the lytic therapy). Amputation-free survival was 83% and 75% at 6 months and 2 years, respectively. Relief of ischemia (defined as relief of claudication or limb salvage without major surgical intervention) was achieved in only 70% and 43% of patients at 30 days and 2 years, respectively (Kaplan-Meier analysis; mean follow-up, 31 months). Patients with aortoiliac disease had significantly better outcomes than those with infrainguinal disease (P =.03). Duration or type of presenting symptoms did not predict outcome. The cost of the initial hospitalization per patient for thrombolysis was $18,490.

CONCLUSION

Thrombolysis can be as or more costly than surgery and is associated with a suboptimal outcome in a significant number of patients. These data lead us to caution against a uniform policy of initial thrombolysis for patients who present with lower extremity ischemia.

Is lower extremity revascularization worthwhile in patients with end-stage renal disease?

BACKGROUND

The purpose of this study was to review the results of lower extremity revascularization in patients with end-stage renal disease and to determine in these patients the functional benefit and cost of an aggressive approach to limb preservation.

METHODS

During a 5-year period at our institution, 33 bypass operations were performed on 31 limbs of 23 dialysis-dependent patients. Indications for revascularization were limited (18) or extensive (12) tissue loss or ischemia without tissue loss (3). Procedures included aortobifemoral bypass (1), femoropopliteal bypass (10), and femorotibial/pedal bypass (22). A digital or transmetatarsal amputation was performed in 57% of limbs.

RESULTS

The 30-day primary patency was 100%. Cumulative primary and secondary patency rates at 2 years were 65% and 79%, respectively. Limb salvage was 67% and 59% at 1 and 2 years, respectively. Patient survival was poor (47% at 2 years). Peritoneal dialysis was predictive of poor survival (P <.001). Four of 5 patients on peritoneal dialysis died within 3 months of intervention. Extensive tissue loss was predictive of a diminished rate of limb salvage (P =.027). Only 39% of limbs with extensive tissue loss were salvaged at 1 year compared with 78% and 100% of limbs with limited and no tissue loss, respectively. The average hospital cost was $44,308 per year of limb salvage.

CONCLUSIONS

Although revascularization of ischemic limbs in dialysis patients can be achieved with an excellent initial graft patency and reasonable limb salvage, patient survival is poor and costs are high. A selective approach to revascularization in these complicated patients may be indicated. For patients treated with peritoneal dialysis and for those with extensive tissue loss, primary amputation may be the preferred approach.

The cost-effectiveness of repairing ruptured abdominal aortic aneurysms

BACKGROUND

Although advances in technology have reduced the operative risk of elective abdominal aortic aneurysm (AAA) repair, the surgical repair of ruptured AAAs is associated with a much poorer prognosis and a higher cost. Accordingly, it has been suggested that patients with predictably high rates of morbidity and mortality from ruptured AAA may not benefit from surgical intervention.

METHODS AND RESULTS

A cost-effectiveness analysis was performed with the use of a Markov decision-analytic model to compute long-term survival in quality-adjusted life years and lifetime costs for a hypothetical cohort of patients with ruptured AAAs managed with either a strategy of open surgical repair or no intervention. Probability estimates for the various outcomes were based on a review of the literature. Average costs of (1) the immediate hospitalization ($28,356) and (2) complications resulting from the procedure were based on the average use of resources as reported in the literature and from a hospital's cost accounting system. Our measure of outcome was the incremental cost-effectiveness ratio. For our base-case analysis, the repair of ruptured AAAs was cost-effective with an incremental cost-effectiveness ratio of $10,754. (Society is usually willing to pay for interventions with cost-effectiveness ratios of less than $60,000; for example, the costeffectiveness ratios for coronary artery bypass grafting and dialysis are $9500 and $54,400, respectively.) In sensitivity analyses, the cost-effectiveness of repairing ruptured AAAs was influenced only by alterations in the operative mortality. If the operative mortality exceeded 88%, repair of ruptured AAAs was no longer cost-effective. As an independent variable, increasing age had no substantial impact on the cost-effectiveness, although it is reported to be associated with increased operative mortality. It was necessary that the patient's cost of the initial hospitalization for ruptured AAA exceed $195,000 before repairing ruptured AAAs was no longer cost-effective.

CONCLUSIONS

Our analysis suggests that despite the high cost and poor outcomes, the surgical repair of ruptured AAAs is still cost-effective when compared with no intervention. The cost of repairing ruptured AAAs falls within society's acceptable limits and therefore should not be a consideration in the management of patients with AAAs.

Is carotid endarterectomy cost-effective in symptomatic patients with moderate (50% to 69%) stenosis?

OBJECTIVE

Recently published data from the North American Carotid Endarterectomy Trial revealed a benefit for carotid endarterectomy (CEA) in symptomatic patients with moderate (50% to 69%) carotid stenosis. This benefit was significant but small (absolute stroke risk reduction at 5 years, 6.5%; 22.2% vs 15.7%), and thus, the authors of this study were tentative in the recommendation of operation for these patients. To better elucidate whether CEA in symptomatic patients with moderate carotid stenosis is a proper allocation of societal resources, we examined the cost-effectiveness of this intervention.

METHODS

A decision-analytic Markov process model was constructed to determine the cost-effectiveness of CEA versus medical treatment for a hypothetical cohort of 66-year-old patients with moderate carotid stenosis. This model allowed the comparison of not only the immediate hospitalization but also the lifetime costs and benefits of these two strategies. Our measure of outcome was the cost-effectiveness ratio (CER), defined as the incremental lifetime cost per quality-adjusted life year saved. We assumed an operative stroke and death rate of 6.6% and a declining risk of ipsilateral stroke after the ischemic event with medical treatment (first year, 9.3%; second year, 4%; subsequent years, 3%). The hospitalization cost of CEA ($6,420) and the annual costs of major stroke ($26,880), minor stroke ($798), and aspirin therapy ($63) were estimated from a hospital cost accounting system and the literature.

RESULTS

CEA for moderate carotid stenosis increased the survival rate by 0.13 quality-adjusted life years as compared with medical treatment at an additional lifetime cost of $580. Thus, CEA was cost-effective with a CER of $4,462. Society is usually willing to pay for interventions with CERs of less than $60,000 (eg, CERs for coronary artery bypass grafting at $9,100 and for dialysis at $53,000). CEA was not cost-effective if the perioperative risk was greater than 11.3%, if the ipsilateral stroke rate associated with medical treatment at 1 year was reduced to 4.3%, if the age of the patient exceeded 83 years, or if the cost of CEA exceeded $13,200.

CONCLUSION

CEA in patients with symptomatic moderate carotid stenosis of 50% to 69% is cost-effective. Perioperative risk of stroke or death, medical and surgical stroke risk, cost of CEA, and age are important determinants of the cost-effectiveness of this intervention.

Assessment of endogenous dopamine release by methylphenidate challenge using iodine-123 iodobenzamide single-photon emission tomography

This double-blind, placebo-controlled study assessed pharmacologically induced endogenous dopamine (DA) release in healthy male volunteers (n=12). Changes in endogenous DA release after injection of the psychostimulant drug methylphenidate were evaluated by single-photon emission tomography (SPET) and constant infusion of iodine-123 iodobenzamide ([123I]IBZM), a D2 receptor radioligand that is sensitive to endogenous DA release. Methylphenidate induced displacement of striatal [123I]IBZM binding, resulting in a significantly decrease in the specific to non-specific [123I]IBZM uptake ratio (average: 8.6%) in comparison with placebo (average: -1.9%). Moreover, injection of methylphenidate induced significant behavioural responses on the following items: excitement, anxiety, tension, and mannerisms and posturing. The results of this study demonstrate the feasibility of using constant infusion of [123I]IBZM and SPET imaging to measure endogenous DA release after methylphenidate challenge and to investigate neurochemical aspects of behaviour.

New mutants of Saccharomyces cerevisiae affected in the transport of proteins from the endoplasmic reticulum to the Golgi complex

We have isolated new temperature-sensitive mutations in five complementation groups, sec31-sec35, that are defective in the transport of proteins from the endoplasmic reticulum (ER) to the Golgi complex. The sec31-sec35 mutants and additional alleles of previously identified sec and vacuolar protein sorting (vps) genes were isolated in a screen based on the detection of alpha-factor precursor in yeast colonies replicated to and lysed on nitrocellulose filters. Secretory protein precursors accumulated in sec31-sec35 mutants at the nonpermissive temperature were core-glycosylated but lacked outer chain carbohydrate, indicating that transport was blocked after translocation into the ER but before arrival in the Golgi complex. Electron microscopy revealed that the newly identified sec mutants accumulated vesicles and membrane structures reminiscent of secretory pathway organelles. Complementation analysis revealed that sec32-1 is an allele of BOS1, a gene implicated in vesicle targeting to the Golgi complex, and sec33-1 is an allele of RET1, a gene that encodes the alpha subunit of coatomer.

[Idiopathic pulmonary hemosiderosis and Goodpasture's syndrome -- radiological findings (author's transl)]

Description of roentgenographic changes in idiopathic pulmonary hemosiderosis and Goodpasture's syndrome. Diagnostic criteria for differentiation from alveolar edema are shown. Separation of disseminated alveolar infections without clinical information is not possible. The close relation to idiopathic pulmonary hemosiderosis and Goodpasture's syndrome is emphasized.