Use of a novel drape 'tent' as an infection prevention control measure for mastoid surgery.

BACKGROUND: Mastoid surgery is an aerosol-generating procedure that involves the use of a high-speed drill, which produces a mixture of water, bone, blood and tissue that may contain the viable coronavirus disease 2019 pathogen. This potentially puts the surgeon and other operating theatre personnel at risk of acquiring the severe acute respiratory syndrome coronavirus-2 from contact with droplets or aerosols. The use of an additional drape designed to limit the spread of droplets and aerosols has been described; such drapes include the 'Southampton Tent' and 'OtoTent'. OBJECTIVES: To evaluate the use of a novel drape 'tent' that has advantages over established 'tent' designs in terms of having: (1) a CE marking; (2) no requirement for modification during assembly; and (3) no obstruction to the surgical visual field. RESULTS AND CONCLUSION: During mastoid surgery, the dispersion of macroscopic droplets and other particulate matter was confined within the novel drape 'tent'. Use of this drape 'tent' had no adverse effects upon the surgeon's manual dexterity or efficiency, the view of the surgical field, or the sterility. Hence, our findings support its use during mastoid surgery in the coronavirus disease 2019 era.

Selective RET kinase inhibition for patients with RET-altered cancers.

Background: Alterations involving the RET kinase are implicated in the pathogenesis of lung, thyroid and other cancers. However, the clinical activity of multikinase inhibitors (MKIs) with anti-RET activity in RET-altered patients appears limited, calling into question the therapeutic potential of targeting RET. LOXO-292 is a selective RET inhibitor designed to inhibit diverse RET fusions, activating mutations and acquired resistance mutations. Patients and methods: Potent anti-RET activity, high selectivity, and central nervous system coverage were confirmed preclinically using a variety of in vitro and in vivo RET-dependent tumor models. Due to clinical urgency, two patients with RET-altered, MKI-resistant cancers were treated with LOXO-292, utilizing rapid dose-titration guided by real-time pharmacokinetic assessments to achieve meaningful clinical exposures safely and rapidly. Results: LOXO-292 demonstrated potent and selective anti-RET activity preclinically against human cancer cell lines harboring endogenous RET gene alterations; cells engineered to express a KIF5B-RET fusion protein -/+ the RET V804M gatekeeper resistance mutation or the common RET activating mutation M918T; and RET-altered human cancer cell line and patient-derived xenografts, including a patient-derived RET fusion-positive xenograft injected orthotopically into the brain. A patient with RET M918T-mutant medullary thyroid cancer metastatic to the liver and an acquired RET V804M gatekeeper resistance mutation, previously treated with six MKI regimens, experienced rapid reductions in tumor calcitonin, CEA and cell-free DNA, resolution of painful hepatomegaly and tumor-related diarrhea and a confirmed tumor response. A second patient with KIF5B-RET fusion-positive lung cancer, acquired resistance to alectinib and symptomatic brain metastases experienced a dramatic response in the brain, and her symptoms resolved. Conclusions: These results provide proof-of-concept of the clinical actionability of RET alterations, and identify selective RET inhibition by LOXO-292 as a promising treatment in heavily pretreated, multikinase inhibitor-experienced patients with diverse RET-altered tumors.

Myocardial infarction and heart failure hospitalization rates in Maine, USA - variability along the urban-rural continuum.

INTRODUCTION: Cardiovascular disease, including myocardial infarction (MI) and heart failure (HF), remains the leading cause of death in wealthy countries and is of increasing concern in low- and middle-income countries as risk factors such as smoking and obesity become more common around the globe. Within each country the health burden of MI and HF generally falls more heavily on those who live in rural areas and on those who live in communities with lower average socioeconomic status (SES). Hospitalization rates are an important measure of community health because high rates may indicate a high burden of poor health, while inappropriately low rates (low hospitalization rates absent evidence of average good health) may indicate underutilization of health services. The objective of this study was to determine the predictors of MI and HF hospitalization rates at town level in the State of Maine, USA. Maine has large variations in wealth and along the urban-rural continuum at town level. Because our results shed light on variations in health and health-seeking behavior for different Maine populations (such as those living closer vs further from hospitals) they may be of interest to providers of healthcare to people who live in areas remote from healthcare, and to people who face other barriers to good cardiovascular health. METHODS: To determine predictors of HF and MI hospitalization in Maine, we constructed a geographic information system (GIS) for Maine's towns using publicly available electronic map layers, year 2000 census data, and electronic hospitalization records for all Maine hospitals. This GIS generated age-corrected MI and HF hospitalization rates for 1998-2002 as dependent variables and the following independent variables: poverty rate, unemployment rate, median income, educational attainment, rurality, physician density, and distance to the closest hospital. Univariable and multiple linear regression analysis were then performed to determine the significant predictors of MI and HF hospitalization rates. RESULTS: During the 5-year study period there were 24 452 hospitalizations of Maine residents to Maine hospitals for MI and 20 330 for HF. In multiple linear regression analysis, greater unemployment, a larger fraction of the population living in poverty, and proximity to a hospital predicted higher MI hospitalization rate (p = 0.000, r-sq = 19.1%) while greater unemployment and proximity to a hospital predicted higher HF hospitalization rate (p = 0.000, r-sq = 8.4%). CONCLUSIONS: Our finding that higher MI and HF hospitalization rates were predicted for towns that had lower SES is in agreement with many previous studies and shows the importance of these variables to health, even in a setting such as Maine with large variability in rurality. The negative relationship between the distance to a hospital and hospitalization rates likely does not represent better health in those living remotely from healthcare. Rather, it may indicate that people who live in communities distant from hospitals are less likely to seek hospitalization. This suggests that patient behavior as well as socioeconomic status may impact heart-related hospitalization in Maine. It highlights the importance of patient and provider education to ensure that people who live remotely from health care are hospitalized appropriately.

Combined electro-acoustic stimulation: a beneficial union?

BACKGROUND: The most pressing problem facing cochlear implant research is no longer making artificial hearing a reality. Instead, it is to develop devices that can more clearly reflect the capabilities of the human auditory system. Current cochlear implants rarely provide adequate pitch perception. As hearing loss commonly affects higher, more than lower frequencies, a possible solution is to preserve acoustic hearing at low frequencies by inserting a short electrode array and thus deliver combined electro-acoustic stimulation (EAS). OBJECTIVE OF REVIEW: To determine whether individuals with severe-to-profound high-frequency hearing loss have realised this predicted benefit of combined EAS, over conventional cochlear implants, with respect to pitch. TYPE OF REVIEW: A systematic review of publications pertaining to the benefits of combined EAS over conventional cochlear implantation, with specific reference to pitch perception. SEARCH STRATEGY: A systematic literature search was conducted across multiple databases and supplemented by searching the reference lists of relevant trials and identified reviews. RESULTS: The included studies suggest an overall benefit of combined EAS, over conventional cochlear implants, with respect to pitch. In addition, (i) 13% sustained a total loss of low-frequency hearing post-implantation of the short electrode array and, (ii) 24% had >20 dB hearing loss across all frequencies and/or total hearing loss. CONCLUSIONS: For patients with severe-to-profound high-frequency hearing loss combined EAS appears to offer a significant, everyday, long-term benefit. However, further clinical trials with larger numbers of candidates are necessary to confirm this finding. The risks involved cannot be ignored, but there is potential for a variety of strategies to improve the safety margin.

Plasma vasopressin concentrations and Fos protein expression in the supraoptic nucleus following osmotic stimulation or hypovolaemia in the ovariectomized rat: effect of oestradiol replacement.

The set points for vasopressin release in response to increasing plasma osmolality and hypovolaemia alter with reproductive status. Here, we studied stimulated vasopressin release following ovariectomy and oestrogen replacement, neuronal activity being measured in terms of immediate early gene expression. Observations were carried out on three groups of female Sprague-Dawley rats. The first group were ovariectomized. The second group were given a subcutaneous oestrogen implant (20 microg/ml oestradiol-17 beta) at the time of ovariectomy. The final group were left intact and observations performed at oestrus. Two weeks after ovariectomy, vascular cannulae were implanted under anaesthesia and at least 48 h allowed for recovery before hormone release was stimulated by infusion of 1.5 M NaCl for 90 min, or hypovolaemia induced by the removal of 10 mg/kg body weight taken in 1-ml aliquots. Blood pressure was monitored, and blood samples were taken for determination of packed cell volume and plasma vasopressin and osmolality. After a minimum of 48 h, the challenge was repeated, the rats anaesthetized, and perfused with 4% paraformaldehyde. Brain sections were processed for immunocytochemical detection of Fos protein. Vasopressin release in response to both stimuli was reduced in ovariectomized compared to intact rats and the response could be substantially restored by oestradiol replacement. The number of Fos positive cells in the supraoptic nucleus of oestrogen-replaced rats was significantly higher than in the ovariectomized group and not statistically different from the intact group.

Oestrogen receptor-beta and neurohypophysial hormones: functional interaction and neuroanatomical localisation.

Oestrogens affect fluid balance, influencing both ingestive behaviour and renal excretion. The renal effects are partly due to altered release of vasopressin and oxytocin. This study was designed to explore the role of oestrogen receptor-beta (ERbeta) in neurohypophysial hormonal function. Following dietary administration, soya isoflavones reach the brain in sufficient concentration to activate ERbeta, but not oestrogen receptor-alpha (ERalpha). ERbeta function was therefore manipulated by feeding rat diets differing in soya isoflavone content. Fluid balance and neurohypophysial hormone release were measured in male rats maintained for 14 days on a soya isoflavone-free diet or one containing 150 microg/g genistein+daidzein. Food and water intake, body weight, urine flow, osmolality and sodium concentrations were determined daily. After 14 days, plasma and urine osmolality and sodium, vasopressin and oxytocin concentrations were determined. There was no significant difference in weight gain between the two groups or in their excretion of sodium and water or plasma sodium and plasma oxytocin. However, plasma vasopressin was significantly lower in the iso-free group. Double-label immunocytochemistry was used to assess colocalisation of ERbeta with the neurohypophysial hormones in male rats. Cell nuclei showing ERbeta immunoreactivity were abundant in the posterior magnocellular paraventricular nucleus (PVNpm) and in the supraoptic nucleus (SON). Vasopressin-immunoreactive neurones were similarly distributed, forming the core of the PVNpm and the ventral portion of the SON; majority were positive for ERbeta. Cells with oxytocin immunoreactivity were located mainly at the periphery of the PVNpm and in the dorsal SON; only approximately a quarter of these cells showed ERbeta immunoreactivity. Thus, the difference in the effects of the soya diet on vasopressin and oxytocin release may be related to the ERbeta-activating properties of this diet and to the preponderance of this receptor in vasopressin as opposed to oxytocin cells.

Use of the percutaneous vascular surgery device for closure of femoral access sites during endovascular aneurysm repair: lessons from our experience.

OBJECTIVES: to evaluate the results of our early experience with a percutaneous closure device for aortic aneurysm repair and to identify device related and patient related factors leading to procedure failure. METHODS: eighty-two percutaneous closures in forty-four patients was performed using the 10F Prostar XL Percutaneous Vascular Surgery device during the repair of 1 iliac, 1 thoracic and 42 abdominal aortic aneurysms. RESULTS: successful closure was achieved in 70 access sites (85%) with 12 sites requiring conversion to an open groin incision. The reasons for failure include difficult device introduction due to a tortuous iliac, deflection of needles due to previous scar, femoral artery occlusion and failure of the device to close the arteriotomy. There was one intraoperative death from retroperitoneal haemorrhage and another patient developed a pseudoaneurysm at the cannulation site. CONCLUSIONS: use of the percutaneous closure device requires very careful patient selection. Preoperative radiological assessment of the ilio-femoral vessels is vital to assess for cacification and tortuosity. High device failure rates can be expected from obese patients and those with scarred groins. When difficulty is encountered during the procedure, there should be a low threshold for conversion to an open groin incision. The device and the method of introduction can be further improved to address some of these issues.

Cyproterone acetate induces a cellular tolerance to cadmium in rat liver epithelial cells involving reduced cadmium accumulation.

Several reports indicate that some steroids, in particular sex steroid hormones, can modify cadmium toxicity. We recently reported that cyproterone acetate (CA), a synthetic steroidal antiandrogen that is closely related in structure to progesterone, affects cadmium toxicity in mice. In the present study, we investigated the effect of CA on cadmium toxicity in a rat liver epithelial cell line (TRL 1215) in vitro. Cells were exposed to various concentrations of CA (0,1,10, or 50 microM) for 24 h and subsequently exposed to cadmium (0,50, or 100 microM; as CdCl2) for an additional 24 h. CA pretreatment resulted in a clear decrease in the sensitivity to cadmium. Additional time course study showed CA pretreatment provided protection against cadmium toxicity but only when given for 6 or more hours prior to cadmium exposure. Cellular cadmium accumulation was markedly reduced (60% decrease) in cells pretreated for 6 or more hours with CA. In the presence of protein synthesis inhibitors the protective effect of CA toward cadmium toxicity was abolished. However, in the presence of the GSH synthesis inhibitor, L-buthionine (S,R)-sulfoximide (BSO), the protective effect of CA toward cadmium toxicity remained. CA alone increased metallothionein (MT) levels 2.4-fold, while cadmium (50 microM) alone resulted in a 8.9-fold increase over control. However, cadmium-induced MT synthesis was markedly decreased by CA pretreatment probably because of reduced cadmium accumulation. Analysis of various metal transporters by bDNA signal amplification assay revealed that the ZnT-1 transporter gene, which encodes for a membrane protein associated with zinc efflux, was expressed three-fold more in CA treated cells than control. These data show that CA pretreatment provides protection against cadmium toxicity in vitro and indicate that this protection is due to a decreased accumulation of cadmium rather than through activation of MT synthesis. This decrease of cellular cadmium accumulation appears to be related to events that require protein synthesis and may be due to activation of the genes associated with zinc efflux.

Differential effects of microsomal enzyme-inducing chemicals on the hepatic expression of rat organic anion transporters, OATP1 and OATP2.

The organic anion transporting polypeptides, Oatp1 (Slc21a1) and Oatp2 (Slc21a5), mediate hepatic uptake of cardiac glycosides. Previously, we demonstrated that chemicals that increase cytochrome P450s differentially affect hepatic uptake of cardiac glycosides. We postulated that increased uptake of cardiac glycosides observed after pretreatment of animals with phenobarbital (PB) and pregnenolone-16alpha-carbonitrile (PCN) occurs via increased hepatic expression of Oatp1 and/or Oatp2. Male Sprague-Dawley rats were injected with PB, PCN, 3-methylcholanthrene (3-MC), or vehicle for 4 days. Branched-DNA (bDNA) signal amplification and Western blot analyses were used to assess hepatic Oatp1 and Oatp2 mRNA and protein, respectively. The expression of Oatp1 was not increased by any chemical treatment. Increases in Oatp2 expression were observed from livers of rats treated with PB and PCN, in which PCN caused a robust elevation of Oatp2 mRNA and protein. Oatp2 expression was suppressed in response to 3-MC. To determine the temporal effects of PCN treatment on the expression of Oatp2, rats were administered PCN, livers were extracted at various times, and Oatp2 expression was analyzed. Maximal expression of Oatp2 mRNA was observed at 24 hours and remained elevated, whereas the amount of Oatp2 protein increased throughout the 96-hour interval. The finding that Oatp2 expression increases in response to PB and PCN is consistent with our previous findings that PB and PCN enhance hepatic uptake of cardiac glycosides. These results suggest that Oatp2, but not Oatp1, is inducible by PB and PCN, which imparts the increased capacity of the liver to extract cardiac glycosides from the plasma.

An update of the Zenith endovascular graft for abdominal aortic aneurysms: initial implantation and mid-term follow-up data.

PURPOSE: To evaluate the initial and mid-term results of the Zenith endovascular grafting system for infrarenal abdominal aortic aneurysms. METHODS: Prospective databases at seven centers were used to assess a cohort of patients that underwent treatment for aortic, aortoiliac, or iliac aneurysms since 1995. Data were analyzed to yield descriptive characteristics that pertained to the patients, the aortic morphologic features, the graft configuration, and the complications. Follow-up imaging data were used to determine size changes of the aneurysm sac, endoleak rates, and further complications. Finally survival data were expressed with a Kaplan-Meier analysis. RESULTS: A total of 528 patients were treated with the Zenith endograft. Most of the patients (66%) were considered to be at a high physiologic risk for open repair. Successful graft implantation was accomplished in all but four patients. An overall endoleak rate of 15% was noted, of which 4% was treated urgently because they were thought to represent attachment site faults. The mean follow-up period was 18 months. A total of eight endograft migrations were detected after 2 years of follow-up with an early version of the system. There were three late conversions; two ruptures occurred during the follow-up period. CONCLUSION: This early and mid-term data support the use of the Zenith endovascular graft for the treatment of aortic and aortoiliac aneurysms in properly selected patients. The risks of significant complications or aneurysm rupture are low.

Endoluminal aortic grafting with renal and superior mesenteric artery incorporation by graft fenestration.

PURPOSE: To explore the use of juxta- and suprarenal aortic segments for endograft fixation in abdominal aortic aneurysm (AAA) patients and to develop methods of graft implantation that use endograft fenestrations to preserve renal and visceral vessel perfusion. METHODS: From August 1998 to May 2000, 13 AAA patients with unsuitable infrarenal aortic necks were treated with custom-designed endovascular grafts employing the juxta- and suprarenal aortic segments for proximal sealing. Flow to 33 renal and superior mesenteric arteries was maintained via graft fenestrations that were aligned by use of radiopaque graft markers. The fenestration-orifice interface for renal arteries was secured with modified balloon-expandable stents. RESULTS: All fenestrated grafts were deployed as planned, and all target vessels (33/33) were preserved. Two patients did not receive any stents, one being the first in the series and another who had incorporation of a renal accessory artery only. Without the use of transgraft stenting, 5 renal arteries would have been occluded by the endograft or poorly perfused. Procedural success was 100%. No conversion to open operation or graft-related complications occurred. There was no primary endoleak in any patient by angiographic criteria. Two patients required additional surgical procedures related to access vessels. Periprocedural mortality at 30 days was nil. Follow-up ranging from 3 to 24 months on all patients has not demonstrated any proximal or distal endoleaks. One stented renal vessel has occluded; all other arteries remain patent at last examination. CONCLUSIONS: This study has demonstrated the ability to successfully place a multifenestrated endoluminal graft in an aortic aneurysm using juxta- and suprarenal aortic segments to obtain a satisfactory seal. Stenting of the fenestration-renal ostium junction has helped to maintain renal patency.

A de novo designed helix-turn-helix peptide forms nontoxic amyloid fibrils.

We report here that a monomeric de novo designed alpha-helix-turn-alpha-helix peptide, alpha t alpha, when incubated at 37 degrees C in an aqueous buffer at neutral pH, forms nonbranching, protease resistant fibrils that are 6-10 nm in diameter. These fibrils are rich in beta-sheet and bind the amyloidophilic dye Congo red. alpha t alpha fibrils thus display the morphologic, structural, and tinctorial properties of authentic amyloid fibrils. Surprisingly, unlike fibrils formed by peptides such as the amyloid beta-protein or the islet amyloid polypeptide, alpha t alpha fibrils were not toxic to cultured rat primary cortical neurons or PC12 cells. These results suggest that the potential to form fibrils under physiologic conditions is not limited to those proteins associated with amyloidoses and that fibril formation alone is not predictive of cytotoxic activity.

dTcf antagonises Wingless signalling during the development and patterning of the wing in Drosophila.

Members of the Tcf family of HMG box-containing transcriptional regulators mediate Wnt signalling in the nucleus. Current models suggest that in the absence of Wnt signalling, Tcf interacts with the repressor protein Groucho and suppresses the expression of Wnt targets. Wnt signalling leads to increases in the level of cytoplasmic beta catenin, which enters the nucleus, displaces Tcf from Groucho and leads to transcriptional activation. In order to test this model we have studied the effects of Drosophila Tcf (dTcf) on signalling by Wingless, a Drosophila member of the Wnt family. We show that overexpression of wild-type dTcf during the development and patterning of the wing antagonises Wingless signalling. Furthermore, increases in the concentration of Armadillo, the Drosophila homologue of beta catenin, do not appear to be sufficient to trigger the change from antagonism to activation. This leads us to suggest that the inactivation of the repressive activity of dTcf requires the activity of Wingless in a manner that is independent of Armadillo. We observe that a Groucho molecule devoid of the WD40 repeats can interact with dTcf and acts as a dominant repressor of Wingless signalling in vivo and in vitro. Coexpression of this molecule with dTcf however, does not lead to enhancement of the repressive effects of dTcf alone. This observation suggests that repression by dTcf might not simply be mediated by an interaction with Groucho but that dTcf may have an intrinsic repressive activity that has to be antagonised by Wingless signalling.

An improved method of preparing the amyloid beta-protein for fibrillogenesis and neurotoxicity experiments.

Synthetic amyloid beta-protein (A beta) is used widely to study fibril formation and the physiologic effects of low molecular weight and fibrillar forms of the peptide on cells in culture or in experimental animals. Not infrequently, conflicting results have arisen in these studies, in part due to variation in the starting conformation and assembly state of A beta. To avoid these problems, we sought a simple, reliable means of preparing A beta for experimental use. We found that solvation of synthetic peptide with sodium hydroxide (A beta x NaOH), followed by lyophilization, produced stocks with superior solubility and fibrillogenesis characteristics. Solubilization of the pretreated material with neutral buffers resulted in a pH transition from approximately 10.5 to neutral, avoiding the isoelectric point of A beta (pI approximately 5.5), at which A beta precipitation and aggregation propensity are maximal. Relative to trifluoroacetate (A beta x TFA) or hydrochloric acid (A beta x HCl) salts of A beta, yields of "low molecular weight A beta" (monomers and/or dimers) were improved significantly by NaOH pretreatment. Time-dependent changes in circular dichroism spectra and Congo red dye-binding showed that A beta x NaOH formed fibrils more readily than did the other A beta preparations and that these fibrils were equally neurotoxic. NaOH pretreatment thus offers advantages for the preparation of A beta for biophysical and physiologic studies.

Activation of the Lck tyrosine protein kinase by the Herpesvirus saimiri tip protein involves two binding interactions.

The Tip protein of Herpesvirus saimiri strain 484C binds to and activates the Lck tyrosine protein kinase. Two sequences in the Tip protein were previously shown to be involved in binding to Lck. A proline-rich region, residues 132-141, binds to the SH3 domain of the Lck protein. We show here that the other Lck-binding domain, residues 104-113, binds to the carboxyl-terminal half of Lck and that this binding does not require the Lck SH3 domain. Mutated Tip containing only one functional Lck-binding domain can bind stably to Lck, although not as strongly as wild-type Tip. Interaction of Tip with Lck through either Lck-binding domain increases the activity of Lck in vivo. Simultaneous binding of both domains is required for maximal activation of Lck. The transient expression of Tip in T cells was found to stimulate both Stat3-dependent and NF-AT-dependent transcription. Mutant forms of Tip lacking one or the other of the two Lck-binding domains retained the ability to stimulate Stat3-dependent transcription. Tip lacking the proline-rich Lck-binding domain exhibited almost wild-type activity in this assay. In contrast, ablation of either Lck-binding domain abolished the ability of Tip to stimulate NF-AT-dependent transcription. Full biological activity of Tip, therefore, appears to require both Lck-binding domains.

Direct binding and activation of STAT transcription factors by the herpesvirus saimiri protein tip.

The Tip protein from Herpesvirus saimiri specifically binds to and activates the protein tyrosine kinase, p56(lck). It has been demonstrated that the expression of Tip in T cells is capable of inducing the DNA binding of members of the signal transducers and activators of transcription (STAT) family of transcription factors. We have examined the mechanism behind which STATs 1 and 3 are activated by Tip expression. Tip becomes tyrosine phosphorylated by p56(lck) at two sites in the amino-terminal tail region. One site of phosphorylation lies within a consensus YXPQ binding motif for the SH2 domains of STATs 1 and 3. We demonstrate that tyrosine phosphorylation of Tip at this site is required for the binding of STATs, and the induction of STAT dependent transcription. Furthermore, we demonstrate that, similar to STAT activation by v-Src, the optimum induction of STAT-dependent transcription by Tip requires Ras/Rac mediated signaling events.

Neurons regulate extracellular levels of amyloid beta-protein via proteolysis by insulin-degrading enzyme.

Progressive cerebral accumulation of amyloid beta-protein (Abeta) is an early and invariant feature of Alzheimer's disease. Little is known about how Abeta, after being secreted, is degraded and cleared from the extracellular space of the brain. Defective Abeta degradation could be a risk factor for the development of Alzheimer's disease in some subjects. We reported previously that microglial cells release substantial amounts of an Abeta-degrading protease that, after purification, is indistinguishable from insulin-degrading enzyme (IDE). Here we searched for and characterized a role for IDE in Abeta degradation by neurons, the principal cell type that produces Abeta. Whole cultures of differentiated pheochromocytoma (PC12) cells and primary rat cortical neurons actively degraded endogenously secreted Abeta via IDE. However, unlike that in microglia, IDE in differentiated neurons was not released but localized to the cell surface, as demonstrated by biotinylation. Undifferentiated PC12 cells released IDE into their medium, whereas after differentiation, IDE was cell associated but still degraded Abeta in the medium. Overexpression of IDE in mammalian cells markedly reduced the steady-state levels of extracellular Abeta(40) and Abeta(42), and the catalytic site mutation (E111Q) abolished this effect. We observed a novel membrane-associated form of IDE that is approximately 5 kDa larger than the known cytosolic form in a variety of cells, including differentiated PC12 cells. Our results support a principal role for membrane-associated and secreted IDE isoforms in the degradation and clearance of naturally secreted Abeta by neurons and microglia.

Isothiocyanate-trigalactose: application for antibody-targeted delivery of diagnostic and therapeutic agents.

Radiolabeled monoclonal antibodies (MAb) and MAb-streptavidin conjugates exhibit slow blood clearance which impedes radioimmunoimaging and radioimmunotherapy. To control blood clearance and lower background levels, lesion-specific targeting proteins can be modified with galactose derivatives for liver uptake via the hepatocyte galactose receptor. In this study, an isothiocyanate-trigalactose derivative (ITC-Tgal) designed for direct coupling to protein amino groups, was synthesized and characterized. In vitro experimentation demonstrated efficient conjugation of ITC-Tgal to streptavidin (SA) and MAb Fab fragment with a corresponding decrease in protein net charge. In vivo studies were conducted with radiolabeled ITC-Tgal modified and native SA and MAb Fab fragment. ITC-Tgal modified SA and Fab fragment exhibited increased blood clearance with the liver uptake and the rate of blood clearance controlled by the extent of ITC-Tgal modification.

A fenestrated covered suprarenal aortic stent.

OBJECTIVE: to address the clinical problem of inadequate neck length of abdominal aortic aneurysms in endoluminal surgery. DESIGN: a covered suprarenal aortic stent was designed with a fenestration to preserve blood flow in a targeted renal artery. METHOD AND MATERIAL: a Dacron-covered stent was accurately cut to size with a fenestration according to pre-imaging studies. RESULTS: the stent was successfully deployed in canine models, preserving the visceral and renal artery of interest. CONCLUSION: by accurately placing a covered stent in the aorta and preserving the blood flow to its branches, it may be possible to extend the indications for endoluminal aortic aneurysm grafting.

Activation of the lck tyrosine-protein kinase by the binding of the tip protein of herpesvirus saimiri in the absence of regulatory tyrosine phosphorylation.

The Tip protein of herpesvirus saimiri 484 binds to the Lck tyrosine-protein kinase at two sites and activates it dramatically. Lck has been shown previously to be activated by either phosphorylation of Tyr394 or dephosphorylation of Tyr505. We examined here whether a change in the phosphorylation of either site was required for the activation of Lck by Tip. Remarkably, mutation of both regulatory sites of tyrosine phosphorylation did not prevent activation of Lck by Tip either in vivo or in a cell free in vitro system. Tip therefore appears to be able to activate Lck through an induced conformational change that does not necessarily involve altered phosphorylation of the kinase. Tip may represent the prototype of a novel type of regulator of tyrosine-protein kinases.