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1.
Ann Surg ; 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38726671

RESUMO

OBJECTIVE: Develop and validate a mortality risk calculator that could be utilized at the time of transfer, leveraging routinely collected variables that could be obtained by trained non-clinical transfer personnel. SUMMARY BACKGROUND DATA: There are no objective tools to predict mortality at the time of inter-hospital transfer for Emergency General Surgery (EGS) patients that are "unseen" by the accepting system. METHODS: Patients transferred to general or colorectal surgery services from January 2016 through August 2022 were retrospectively identified and randomly divided into training and validation cohorts (3:1 ratio). The primary outcome was admission-related mortality, defined as death during the index admission or within 30 days post-discharge. Multiple predictive models were developed and validated. RESULTS: Among 4,664 transferred patients, 280 (6.0%) experienced mortality. Predictive models were generated utilizing 19 routinely collected variables; the penalized regression model was selected over other models due to excellent performance using only 12 variables. The model performance on the validating set resulted in an area under the receiver operating characteristic curve, sensitivity, specificity, and balanced accuracy of 0.851, 0.90, 0.67, and 0.79, respectively. After bias correction, Brier score was 0.04, indicating a strong association between the assigned risk and the observed frequency of mortality. CONCLUSION: A risk calculator using twelve variables has excellent predictive ability for mortality at the time of interhospital transfer among "unseen" EGS patients. Quantifying a patient's mortality risk at the time of transfer could improve patient triage, bed and resource allocation, and standardize care.

2.
Liver Transpl ; 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38833290

RESUMO

Ex situ normothermic machine perfusion (NMP) helps increase the use of extended criteria donor livers. However, the impact of an NMP program on waitlist times and mortality has not been evaluated. Adult patients listed for liver transplant (LT) at 2 academic centers from January 1, 2015, to September 1, 2023, were included (n=2773) to allow all patients ≥6 months follow-up from listing. Routine NMP was implemented on October 14, 2022. Waitlist outcomes were compared from pre-NMP pre-acuity circles (n=1460), pre-NMP with acuity circles (n=842), and with NMP (n=381). Median waitlist time was 79 days (IQR: 20-232 d) at baseline, 49 days (7-182) with acuity circles, and 14 days (5-56) with NMP ( p <0.001). The rate of transplant-per-100-person-years improved from 61-per-100-person-years to 99-per-100-person-years with acuity circles and 194-per-100-person-years with NMP ( p <0.001). Crude mortality without transplant decreased from 18.3% (n=268/1460) to 13.3% (n=112/843), to 6.3% (n=24/381) ( p <0.001) with NMP. The incidence of mortality without LT was 15-per-100-person-years before acuity circles, 19-per-100 with acuity circles, and 9-per-100-person-years after NMP ( p <0.001). Median Model for End-Stage Liver Disease at LT was lowest with NMP, but Model for End-Stage Liver Disease at listing was highest in this era ( p <0.0001). The median donor risk index of transplanted livers at baseline was 1.54 (1.27-1.82), 1.66 (1.42-2.16) with acuity circles, and 2.06 (1.63-2.46) with NMP ( p <0.001). Six-month post-LT survival was not different between eras ( p =0.322). The total cost of health care while waitlisted was lowest in the NMP era ($53,683 vs. $32,687 vs. $23,688, p <0.001); cost-per-day did not differ between eras ( p =0.152). The implementation of a routine NMP program was associated with reduced waitlist time and mortality without compromising short-term survival after liver transplant despite increased use of riskier grafts. Routine NMP use enables better waitlist management with reduced health care costs.

3.
J Surg Oncol ; 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39082443

RESUMO

BACKGROUND: Neoadjuvant systemic therapy (NAST) is a treatment option for intrahepatic cholangiocarcinoma (iCCA), though its impact on short-term oncologic outcomes and long-term survival remains relatively unknown. METHODS: The National Cancer Database (NCDB) between 2004 and 2019 was queried for patients with reportedly resectable (Stage I-IIIB) iCCA who received curative-intent resection with lymphadenectomy. Propensity matching was performed between groups based on the use of NAST and groups were compared for overall survival (OS) and oncologic outcomes, including nodal harvest, rate of node positivity, rate of positive margins, and administration of adjuvant therapy. RESULTS: Two thousand and five hundred ninety-six patients met inclusion criteria; 364 (14%) received NAST versus 1763 (68%) up-front resection. After matching, 332 pairs of patients were matched between NAST and no NAST. Patients receiving NAST had a greater nodal harvest (OR = 1.26 [1.09-1.88]; p < 0.001) and a lower rate of node positivity (OR = 0.67 [0.49-0.63]; p < 0.001). Patients without NAST were more likely to complete adjuvant systemic therapy (OR = 0.45 [0.33-0.62]; p < 0.001). However, patients receiving NAST had no OS benefit after resection compared to those who did not receive NAST (median OS 48.3 ± 5.3 vs. 38.8 ± 3.7 months; p = 0.160). Node-positive disease (OR = 2.10 [1.78-2.45]; p < 0.001) conferred the greatest risk for reduced OS followed by positive-margin resection (OR = 1.42 [1.21-1.47]; p < 0.001) and increasing T-stage (OR = 1.34 [1.21-1.47]; p < 0.001). CONCLUSION: NAST for iCCA was associated with improved quality of oncologic resection but did not confer an OS benefit versus up-front resection.

4.
J Surg Oncol ; 2024 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-39155652

RESUMO

Secondary liver malignancies are a serious and challenging global health concern. Secondary metastasis to the liver is most commonly from colorectal cancer that has metastatically spread through splanchnic circulation. Metastatic diseases can portend poor prognosis due to the progressive nature typically found on detection. Improvements in detection of disease, monitoring therapy response, and monitoring for recurrence are crucial to the improvement in the management of secondary liver malignancies. Assessment of ctDNA in these patient populations poses an opportunity to impact the management of secondary liver malignancies. In this review, we aim to discuss ctDNA, the current literature, and future directions of this technology within secondary liver malignancies.

5.
J Surg Oncol ; 2024 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-39155663

RESUMO

Primary liver malignancies are a serious and challenging global health concern. The most common primary tumors are hepatocellular carcinoma and cholangiocarcinoma. These diseases portend poor prognosis when presenting with progressive, extensive disease. There is a critical need for improved diagnosis, therapeutic intervention, and monitoring surveillance in liver-related malignancies. Liquid biopsy using ctDNA provides an opportunity for growth within these domains for liver-related malignancy. However, ctDNA is relatively understudied in this field compared with other solid tumor types, possibly due to the complex nature of the pathology. In this review, we aim to discuss ctDNA, the current literature, and future directions of this technology within primary liver malignancies.

6.
Surg Endosc ; 38(5): 2602-2610, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38498210

RESUMO

INTRODUCTION: Minimally invasive Pancreatoduodenectomy (MIPD), or the Whipple procedure, is increasingly utilized. No study has compared laparoscopic (LPD) and robotic (RPD) approaches, and the impact of the learning curve on oncologic, technical, and post-operative outcomes remains relatively understudied. METHODS: The National Cancer Database was queried for patients undergoing LPD or RPD from 2010 to 2020 with a diagnosis of pancreatic cancer. Outcomes were compared between approaches using propensity-score matching (PSM); the impact of annual center-level volume of MIPD was also assessed by dividing volume into quartiles. RESULTS: A total of 3,342 patients were included. Most (n = 2,716, 81.3%) underwent LPD versus RPD (n = 626, 18.7%). There was a high rate (20.2%, n = 719) of positive margins. Mean length-of-stay (LOS) was 10.4 ± 8.9 days. Thirty-day mortality was 2.8% (n = 92) and ninety-day mortality was 5.7% (n = 189). PSM matched 625 pairs of patients receiving LPD or RPD. After PSM, there was no differences between groups based on age, sex, race, CCI, T-stage, neoadjuvant chemo/radiotherapy, or type of PD. After PSM, there was a higher rate of conversion to open (HR = 0.68, 95%CI = 0.50-0.92)., but there was no difference in LOS (HR = 1.00, 95%CI = 0.92-1.11), 30-day readmission (HR = 1.08, 95% CI = 0.68-1.71), 30-day (HR = 0.78, 95% CI = 0.39-1.56) or 90-day mortality (HR = 0.70, 95% CI = 0.42-1.16), ability to receive adjuvant therapy (HR = 1.15, 95% CI = 0.92-1.44), nodal harvest (HR = 1.01, 95%CI = 0.94-1.09) or positive margins (HR = 1.19, 95% CI = 0.89-1.59). Centers in lower quartiles of annual volume of MIPD demonstrated reduced nodal harvest (p = 0.005) and a higher rate of conversion to open (p = 0.038). Higher-volume centers had a shorter LOS (p = 0.012), higher rate of initiation of adjuvant therapy (p = 0.042), and, most strikingly, a reduction in 90-day mortality (p = 0.033). CONCLUSION: LPD and RPD have similar surgical and oncologic outcomes, with a lower rate of conversion to open in the robotic cohort. The robotic technique does not appear to eliminate the "learning curve", with higher volume centers demonstrating improved outcomes, especially seen at minimum annual volume of 5 cases.


Assuntos
Laparoscopia , Neoplasias Pancreáticas , Pancreaticoduodenectomia , Pontuação de Propensão , Procedimentos Cirúrgicos Robóticos , Humanos , Pancreaticoduodenectomia/métodos , Pancreaticoduodenectomia/estatística & dados numéricos , Procedimentos Cirúrgicos Robóticos/estatística & dados numéricos , Procedimentos Cirúrgicos Robóticos/métodos , Masculino , Neoplasias Pancreáticas/cirurgia , Neoplasias Pancreáticas/mortalidade , Neoplasias Pancreáticas/patologia , Feminino , Laparoscopia/métodos , Laparoscopia/estatística & dados numéricos , Idoso , Pessoa de Meia-Idade , Resultado do Tratamento , Tempo de Internação/estatística & dados numéricos , Complicações Pós-Operatórias/epidemiologia , Estudos Retrospectivos , Margens de Excisão , Curva de Aprendizado
7.
Surgeon ; 22(4): 236-241, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38862376

RESUMO

INTRODUCTION: As hospitals strive to reduce their environmental footprint, there is an ongoing debate over the environmental implications of reusable versus disposable linens in operating rooms (ORs). This research aimed to compare the environmental impact of reusable versus single-use OR bed covers and lift sheets using life cycle assessment (LCA) methodology. METHODS: LCA is an established tool with rigorous methodology that uses science-based processes to measure environmental impact. This study compared the impacts of three independent system scenarios at a single large academic hospital: reusable bed covers with 50 laundry cycles and subsequent landfill disposal (System 1), single-use bed covers with waste landfill disposal (System 2), and single-use bed covers with waste disposal using incineration (System 3). RESULTS: The total carbon footprint of System 1 for 50 uses was 19.83 â€‹kg carbon dioxide equivalents (CO2-eq). System 2 generated 64.99 â€‹kg CO2-eq. For System 3, the total carbon footprint was 108.98 â€‹kg CO2-eq. The raw material extraction for all the material to produce an equivalent 50 single-use OR bed cover kits was tenfold more carbon-intensive than the reusable bed cover. Laundering one reusable OR bed cover 50 times was more carbon intensive (12.12 â€‹kg CO2-eq) than landfill disposal of 50 single-use OR bed covers (2.52 â€‹kg CO2-eq). DISCUSSION: Our analysis demonstrates that one reusable fabric-based OR bed cover laundered 50 times, despite the carbon and water-intensive laundering process, exhibits a markedly lower carbon footprint than its single-use counterparts. The net difference is 45.16 â€‹kg CO2-eq, equivalent to driving 115 miles in an average gasoline-powered passenger vehicle. This stark contrast underscores the efficacy of adopting reusable solutions to mitigate environmental impact within healthcare facilities.


Assuntos
Pegada de Carbono , Reutilização de Equipamento , Salas Cirúrgicas , Humanos , Roupas de Cama, Mesa e Banho , Equipamentos Descartáveis , Meio Ambiente , Reciclagem
9.
J Gastrointest Surg ; 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39214400

RESUMO

BACKGROUND: Branch-duct intraductal papillary mucinous neoplasms (BD-IPMNs) are becoming more prevalent with advanced medical imaging and account for most of pancreatic cystic neoplasms (PCNs). Most incidental lesions should be surveyed, with resection reserved for specific, high-risk cases. Solid organ transplantation candidates may be high risk of resection before transplant and will require systemic immunosuppression after transplant, which has been theorized to alter the natural history of the IPMN. We aimed to describe the progression in surveilled cysts after solid organ transplantation. METHODS: A prospectively maintained database of PCNs was queried for patients with IPMN. Patients who had received a previous solid organ transplantation and with ≥2 imaging studies >6 months apart after transplantation were included. Clinically relevant (CR) progression was defined as symptoms, worrisome/high-risk stigmata, or invasive carcinoma (IC). Growth ≥5 mm in 2 years is considered CR progression; size ≥3 cm alone is not. RESULTS: Between 1997 and 2023, 252 patients received solid organ transplantation (liver, 86; kidney, 113; and lung, 54) and were diagnosed as having an IPMN. This cohort was compared with a set of 770 patients surveilled for IPMN who did not have previous transplantation. Median follow-up period was 3.7 years (IQR, 1.6-6.8). Moreover, 2 transplant patients (0.8%) developed IC, and 4 developed (1.6%) high-grade dysplasia (HGD). Both were less common in transplant patients than the nontransplant population (IC, 3.3%; HGD, 2.9%), although this was not significant on time-to-event analysis (IC, P = .152; HGD, P = .352). The rate of CR progression was high in the transplant cohort (n = 118; 47%). Features of CR progression included size growth (n = 79; 67%), other worrisome/high-risk stigmata (n = 25; 21%), and new main duct involvement (n = 14; 12%). Compared with the nontransplant (n = 128; 17%), transplant patients had a higher rate of CR progression (P < .001), which was mostly explained by a more frequent size growth (31% vs 9%; P < .001). However, no transplant patients with size growth CR progression developed IC. Moreover, 17 (6.7%) required pancreatic surgery for CR progression after transplant vs 58 (7.5%) in the nontransplant population. Furthermore, 6 resected cysts (35%) harbored high-risk pathology after transplant (IC, 2; HGD, 4) vs 40 (69%) in the general population (P < .001; IC, 29; HGD, 11). CONCLUSION: Malignant transformation of BD-IPMNs is rare despite systemic immunosuppression in solid organ transplant patients. This supports transplantation in patients with IPMN without fear of worsening their risk of pancreatic cancer, although it was associated with a higher risk of disease progression. Patients with IPMNs should be surveilled with yearly scans after transplant, with pancreatic resection reserved for only high-risk features as we continue to define the optimal criteria for those with CR progression.

10.
Cancers (Basel) ; 16(8)2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38672535

RESUMO

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death and the sixth most diagnosed malignancy worldwide. Serum alpha-fetoprotein (AFP) is the traditional, ubiquitous biomarker for HCC. However, there has been an increasing call for the use of multiple biomarkers to optimize care for these patients. AFP, AFP-L3, and prothrombin induced by vitamin K absence II (DCP) have described clinical utility for HCC, but unfortunately, they also have well established and significant limitations. Circulating tumor DNA (ctDNA), genomic glycosylation, and even totally non-invasive salivary metabolomics and/or micro-RNAS demonstrate great promise for early detection and long-term surveillance, but still require large-scale prospective validation to definitively validate their clinical validity. This review aims to provide an update on clinically available and emerging biomarkers for HCC, focusing on their respective clinical strengths and weaknesses.

11.
Catheter Cardiovasc Interv ; 81(7): 1188-93, 2013 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-23172706

RESUMO

OBJECTIVES: We used the Amplatzer Vascular Plug II to close tubular patent ductus arteriosus (DA) in infants. BACKGROUND: Despite advancements in device design, catheter-based therapy for the DA of tubular morphology has been problematic. Likewise, the currently available devices are not designed to close DAs in small, often premature infants as the size of the delivery systems can be prohibitive and the devices obstructive to aortic or pulmonary artery flow. METHODS: We report our experience using the second-generation Amplatzer Vascular Plug (AVP II) in 10 patients with sizeable, tubular DAs, seven of whom were less than or equal to 4.0 kg. RESULTS: Complete closure was attained in all patients, with one minor complication. In four small infants, the device was delivered without arterial access under echocardiographic guidance. CONCLUSION: It is our belief that the AVP II device can be a useful embolization device for DAs in this difficult patient population.


Assuntos
Cateterismo Cardíaco/instrumentação , Permeabilidade do Canal Arterial/terapia , Fatores Etários , Peso Corporal , Cateterismo Cardíaco/efeitos adversos , Angiografia Coronária , Permeabilidade do Canal Arterial/diagnóstico , Ecocardiografia Doppler em Cores , Desenho de Equipamento , Humanos , Lactente , Estudos Retrospectivos , Resultado do Tratamento
12.
Nat Commun ; 13(1): 4733, 2022 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-36096993

RESUMO

Memories are stored in the brain as cellular ensembles activated during learning and reactivated during retrieval. Using the Tet-tag system in mice, we label dorsal dentate gyrus neurons activated by positive, neutral or negative experiences with channelrhodopsin-2. Following fear-conditioning, these cells are artificially reactivated during fear memory recall. Optical stimulation of a competing positive memory is sufficient to update the memory during reconsolidation, thereby reducing conditioned fear acutely and enduringly. Moreover, mice demonstrate operant responding for reactivation of a positive memory, confirming its rewarding properties. These results show that interference from a rewarding experience can counteract negative affective states. While memory-updating, induced by memory reactivation, involves a relatively small set of neurons, we also find that activating a large population of randomly labeled dorsal dentate gyrus neurons is effective in promoting reconsolidation. Importantly, memory-updating is specific to the fear memory. These findings implicate the dorsal dentate gyrus as a potential therapeutic node for modulating memories to suppress fear.


Assuntos
Medo , Hipocampo , Animais , Medo/fisiologia , Hipocampo/fisiologia , Aprendizagem , Memória/fisiologia , Camundongos , Neurônios/fisiologia
13.
J Pediatr Adolesc Gynecol ; 33(3): 302-306, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31874315

RESUMO

STUDY OBJECTIVE: We aim to explore the impact of an interprofessional graduate student-led sexual education curriculum on sexual self-efficacy, perceived importance of sexual consent, and willingness to intervene against sexual violence in the high-risk population of detained youths. DESIGN, SETTING, AND PARTICIPANTS: Medical, nursing, social work, and physician assistant students implemented a 3-session, comprehensive sexual health curriculum for detained youths (n = 253). INTERVENTIONS AND MAIN OUTCOME MEASURES: The curriculum from Son et al (2017) was adapted to include a more targeted curriculum on consent and safe relationships. Youths completed pre- and postintervention assessments that evaluated their sexual self-efficacy and violence-related beliefs and behaviors. RESULTS: Detained youths completing the curriculum showed statistically significant increases in the sexual self-efficacy (P < .001), view of the importance of consent (P < .001), and willingness to intervene (P = .0027). The subset of male individuals and adolescents aged 17-19 years achieved statistically significant improvement in each category; adolescents aged 12-14 years did not. Female participants showed statistically significant improvement in sexual self-efficacy scores only. CONCLUSIONS: The curriculum addressing topics of consent and sexual violence was effective in improving detained youths' belief in their ability to safely navigate a sexual encounter and their attitudes toward sexual assault. Additional research on gender- and age-specific programming and the long-term impact on sexual health risk behaviors is needed.


Assuntos
Autoeficácia , Educação Sexual/organização & administração , Delitos Sexuais/prevenção & controle , Adolescente , Adulto , Criança , Currículo , Feminino , Humanos , Delinquência Juvenil/psicologia , Masculino , Avaliação de Programas e Projetos de Saúde , Delitos Sexuais/psicologia , Estudantes , Adulto Jovem
14.
Mol Vis ; 14: 81-9, 2008 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-18253099

RESUMO

PURPOSE: Amyloid fibrils are associated with a variety of human protein misfolding and protein deposition diseases. Previous studies have shown that bovine crystallins form amyloid fibers under denaturing conditions and amyloid fibers accumulate in the lens of mice carrying mutations in crystallin genes. Within differentiating lens fiber cells, crystallins may be exposed to low pH lysosome compartments. We have investigated whether human gammaD-crystallin forms amyloid fibrils in vitro, when exposed to low pH partially denaturing conditions. METHODS: Human gammaD-crystallin expressed and purified from E. coli, is stable and soluble at 37 degrees C, pH7, and refolds from the fully denatured state back to the native state under these conditions. Purified Human gammaD-crystallin as well as its isolated NH2- and COOH-terminal domains were incubated at acid pH and subsequently examined by transmission electron microscopy, absorption spectroscopy in the presence of Congo red, FTIR, and low-angle X-ray scattering. RESULTS: Incubation of the intact protein at 37 degrees C in 50 mM acetate buffer pH 3 at 50 mg/ml for 2 days, led to formation of a viscous, gel-like solution. Examination of negatively stained samples by transmission electron microscopy revealed linear, non-branching fibrils of variable lengths, with widths ranging from 15 to 35 nm. Incubation with the dye Congo red generated the spectral red shift associated with dye binding to amyloid. Low-angle X-ray scattering from samples showed clear meridional reflection at 4.7 A and a more diffuse reflection on the equator between 10 and 11 A which is the typical "cross-beta" X-ray fiber diffraction pattern for amyloid fibers. FTIR was used to follow the evolution of the secondary structure of gammaD-crystallin with time during incubation of the protein at pH 3. The native protein displayed a major band at 1640 cm-1 that converted during incubation at 37 degrees C to a band at 1616 cm-1. An additional band at 1689 cm-1 also appeared with time. The presence of bands in the regions about 1620 cm-1 and about 1680 cm-1 has been attributed to the formation of intermolecular beta-sheet structure that characterizes the fibrillar amyloid motif. The isolated NH2-terminal 1-82 and COOH-terminal 86-174 domains of HgammaD-crystallin also formed amyloid fibrils after incubation under the same conditions, but to a lesser extent than the full length. CONCLUSIONS: HgammaD-crystallin, as well as its isolated NH2-terminal 1-82 and COOH-terminal 86-174 domains of HgammaD-crystallin formed amyloid fibrils upon incubation at acid pH. Investigations of early stages in cataract formation within the lens will be required to assess whether amyloid fibrils play a role in the initiation of cataract in vivo.


Assuntos
Amiloide/fisiologia , Cristalinas/química , Cristalinas/fisiologia , Amiloide/metabolismo , Amiloide/ultraestrutura , Corantes/metabolismo , Vermelho Congo/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Microscopia Eletrônica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , gama-Cristalinas
15.
Curr Alzheimer Res ; 5(3): 288-307, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18537544

RESUMO

Targeting the initial formation of amyloid assemblies is a preferred approach to therapeutic intervention in amyloidoses, which include such diseases as Alzheimer's, Parkinson's, Huntington's, etc., as the early-stage, oligomers that form before the development of beta-conformation-rich fibers are thought to be toxic. X-ray patterns from amyloid assemblies always show two common intensity maxima: one at 4.7 A corresponding to the hydrogen-bonding spacing between the beta-chains, and the other at approximately 10 A corresponding to the spacing between beta-pleated sheets. We report here the application of fiber x-ray diffraction to monitor these structural indicators of amyloid fiber assembly in the presence of small, aromatic molecules, some of which have been assessed by other techniques as being inhibitory. The compounds included butylated hydroxytoluene, chloramphenicol, cotinine, curcumin, diphenylalanine (FF), ethyl 3-aminobenzoate methane sulfonate, hexachlorophene, melatonin, methylpyrrolidine, morin, nicotine, phenolphthalaine, PTI-00703 (Cat's claw), pyridine, quinine, sulfadiazine, tannic acid, tetracaine, tetrachlorosalicylanilide, and tetracycline. Their effects on the aggregation of Abeta1-40, Abeta11-25, Abeta12-28, Abeta17-28, Abeta16-22, and Abeta16-22[methylated] analogues were characterized in terms of the integral widths and integrated intensities of the two characteristic reflections. Peptide Abeta11-25 with or without small molecules showed varying relative intensities but similar coherent lengths of 28-49 A in the intersheet and 171-221 A in the H-bonding directions. PTI-00703, however, abolished the H-bonding reflection. Among previously reported aromatic inhibitors for Abeta11-25, PTI-00703, tannic acid, and quinine were more effective than curcumin, morin, and melatonin based on the criterion of crystallite volume. For the N-methylated and control samples, there were no substantial differences in spacings and coherent lengths; however, the relative volumes of the beta-crystallites, which were calculated from the magnitude of the intensities, decreased with increase in concentration of Abeta16-22Me. This may be accounted for by the binding of Abeta16-22Me to the monomer or preamyloid oligomer of Abeta16-22. The fiber diffraction approach, which can help to specify whether an amyloidophilic compound acts by impeding hydrogen-bonding or by altering intersheet interactions, may help provide a rationale basis for the development of other therapeutic reagents.


Assuntos
Peptídeos beta-Amiloides/efeitos dos fármacos , Hidrocarbonetos Aromáticos/farmacologia , Fragmentos de Peptídeos/efeitos dos fármacos , Estrutura Secundária de Proteína/efeitos dos fármacos , Difração de Raios X , Peptídeos beta-Amiloides/química , Fragmentos de Peptídeos/química , Dobramento de Proteína
16.
Biophys J ; 93(10): 3515-28, 2007 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-17693467

RESUMO

Solution spectroscopy studies on the cytoplasmic domain of human myelin protein zero (P0) (hP0-cyt) suggest that H-bonding between beta-strands from apposed molecules is likely responsible for the tight cytoplasmic apposition in compact myelin. As a follow-up to these findings, in the current study we used circular dichroism and x-ray diffraction to analyze the same type of model membranes previously used for hP0-cyt to investigate the molecular mechanism underlying the zebrafish cytoplasmic apposition. This space is significantly narrower in teleosts compared with that in higher vertebrates, and can be accounted for in part by the much shorter cytoplasmic domain in the zebrafish protein (zP0-cyt). Circular dichroism measurements on zP0-cyt showed similar structural characteristics to those of hP0-cyt, i.e., the protein underwent a beta-->alpha structural transition at lipid/protein (L/P) molar ratios >50, and adopted a beta-conformation at lower L/P molar ratios. X-ray diffraction was carried out on lipid vesicle solutions with zP0-cyt before and after dehydration to study the effect of protein on membrane lipid packing. Solution diffraction revealed the electron-density profile of a single membrane bilayer. Diffraction patterns of dried samples suggested a multilamellar structure with the beta-folded P0-cyt located at the intermembrane space. Our findings support the idea that the adhesive role of P0 at the cytoplasmic apposition in compact myelin depends on the cytoplasmic domain of P0 being in the beta-conformation.


Assuntos
Proteína P0 da Mielina/química , Sequência de Aminoácidos , Animais , Citoplasma/metabolismo , Bicamadas Lipídicas/química , Lipídeos/química , Modelos Estatísticos , Dados de Sequência Molecular , Peptídeos/química , Ligação Proteica , Conformação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Difração de Raios X , Peixe-Zebra
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