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1.
Radiol Case Rep ; 16(3): 670-672, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33488896

ABSTRACT

Abdominal compartment syndrome can be a lethal entity when not treated in a timely fashion. Current standard of care involves emergent decompressive laparotomy by the surgical team. In this case, a 52-year-old male who developed abdominal compartment syndrome secondary to hemoperitoneum underwent emergent drain placement as decompressive laparotomy was not an optimal option for management. Little literature exists on the utility of drain placement or paracentesis for decompression in overall patient morbidity and mortality. However, when necessary, drain placement shows similar outcomes when compared to the standard of care. Interventional radiologists are uniquely positioned to provide drainage guided management for abdominal compartment syndrome in emergent settings.

2.
Sensors (Basel) ; 20(11)2020 Jun 08.
Article in English | MEDLINE | ID: mdl-32521711

ABSTRACT

Living walls are important vertical greening systems with modular prevegetated structures. Studies have suggested that living walls have many social benefits as an ecological engineering technique with notable potential for reconciliation ecology. Despite these benefits, there are currently no mature workflows or technologies for monitoring the health status and water stress of living wall systems. To partially fill the current knowledge gap related to water stress, we acquired thermal, multispectral, and hyperspectral remote sensing data from an indoor living wall in the Cloud Forest of the Gardens by the Bay, Singapore. The surface temperature (Ts) and a normalized difference vegetation index (NDVI) were obtained from these data to construct a Ts-NDVI space for applying the "triangle method". A simple and effective algorithm was proposed to determine the dry and wet edges, the key components of the said method. The pixels associated with the dry and wet edges were then selected and highlighted to directly display the areas under water-stress conditions. Our results suggest that the proposed algorithm can provide a reasonable overview of the water-stress information of the living wall; therefore, our method can be simple and effective to monitor the health status of a living wall. Furthermore, our work confirms that the triangle method can be transferred from the outdoors to an indoor environment.


Subject(s)
Dehydration , Environmental Monitoring , Forests , Plant Physiological Phenomena , Remote Sensing Technology , Singapore , Temperature
3.
Am J Physiol Lung Cell Mol Physiol ; 310(11): L1071-7, 2016 06 01.
Article in English | MEDLINE | ID: mdl-27106292

ABSTRACT

Libby amphibole (LA) causes a unique progressive lamellar pleural fibrosis (LPF) that is associated with pulmonary function decline. Pleural fibrosis among the LA-exposed population of Libby, MT, has been associated with the production of anti-mesothelial cell autoantibodies (MCAA), which induce collagen production from cultured human mesothelial cells. We hypothesized that the progressive nature of LPF could be at least partially attributed to an autoimmune process and sought to demonstrate that LA-induced MCAA trigger collagen deposition in vivo. C57BL/6 mice were exposed to LA for 7 mo, and serum was tested for MCAA by cell-based ELISA on primary mouse mesothelial cells. When treated in vitro with serum from mice exposed to LA, mesothelial cells upregulated collagen matrix production. This effect was lost when the serum was cleared of IgG using protein G beads, implicating IgG autoantibodies. Using the peritoneal cavity as a surrogate for the pleural cavity, groups of naïve (non-asbestos-exposed) mice were injected intraperitoneally with 1) control serum, 2) one dose of serum from LA-exposed mice (LA serum), 3) two doses of LA serum, or 4) two doses of LA serum cleared of IgG. After 1 mo, analysis of collagen in peritoneal walls using two-photon confocal microscopy (SHG analysis) and a hydroxyproline assay demonstrated significant increases in collagen by LA serum but not control or cleared serum. These data support the hypothesis that MCAA in LA-exposed mice induce fibrotic responses in vivo, demonstrating that an autoimmune component may be contributing to the progressive pleural fibrosis seen in LA-exposed patients.


Subject(s)
Asbestos, Amphibole/toxicity , Asbestosis/immunology , Autoantibodies/immunology , Epithelial Cells/immunology , Fibrillar Collagens/metabolism , Animals , Asbestosis/metabolism , Cells, Cultured , Epithelium/immunology , Epithelium/pathology , Lung/immunology , Lung/pathology , Mice, Inbred C57BL , Pleural Diseases/immunology , Pleural Diseases/metabolism , Primary Cell Culture
4.
J Org Chem ; 79(19): 9170-8, 2014 Oct 03.
Article in English | MEDLINE | ID: mdl-25184438

ABSTRACT

The methylerythritol phosphate biosynthetic pathway, found in most Bacteria, some parasitic protists, and plant chloroplasts, converts D-glyceraldehyde phosphate and pyruvate to isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), where it intersects with the mevalonate pathway found in some Bacteria, Archaea, and Eukarya, including the cytosol of plants. D-3-Methylerythritol-4-phosphate (MEP), the first pathway-specific intermediate in the pathway, is converted to IPP and DMAPP by the consecutive action of the IspD-H proteins. We synthesized five D-MEP analogues-D-erythritol-4-phosphate (EP), D-3-methylthrietol-4-phosphate (MTP), D-3-ethylerythritol-4-phosphate (EEP), D-1-amino-3-methylerythritol-4-phosphate (NMEP), and D-3-methylerythritol-4-thiolophosphate (MESP)-and studied their ability to function as alternative substrates for the reactions catalyzed by the IspDF fusion and IspE proteins from Agrobacterium tumefaciens, which covert MEP to the corresponding eight-membered cyclic diphosphate. All of the analogues, except MTP, and their products were substrates for the three consecutive enzymes.


Subject(s)
Agrobacterium tumefaciens/chemistry , Agrobacterium tumefaciens/enzymology , Bacterial Proteins/chemistry , Erythritol/analogs & derivatives , Hemiterpenes/chemistry , Multienzyme Complexes/metabolism , Organophosphorus Compounds/chemistry , Organophosphorus Compounds/chemical synthesis , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Sugar Phosphates/chemical synthesis , Agrobacterium tumefaciens/metabolism , Catalysis , Enzyme Assays , Erythritol/chemical synthesis , Erythritol/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Multienzyme Complexes/chemistry , Phosphotransferases (Alcohol Group Acceptor)/chemistry , Substrate Specificity , Sugar Phosphates/chemistry
5.
J Psychiatr Res ; 58: 69-75, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25082653

ABSTRACT

The main enzyme for serotonin degradation, monoamine oxidase (MAO) A, has recently emerged as a key biological factor in the predisposition to impulsive aggression. Male carriers of low-activity variants of the main functional polymorphism of the MAOA gene (MAOA-uVNTR) have been shown to exhibit a greater proclivity to engage in violent acts. Thus, we hypothesized that low-activity MAOA-uVNTR alleles may be associated with a higher risk for criminal violence among male offenders. To test this possibility, we analyzed the MAOA-uVNTR variants of violent (n = 49) and non-violent (n = 40) male Caucasian and African-American convicts in a correctional facility. All participants were also tested with the Childhood Trauma Questionnaire (CTQ), Barratt Impulsivity Scale (BIS-11) and Buss-Perry Aggression Questionnaire (BPAQ) to assess their levels of childhood trauma exposure, impulsivity and aggression, respectively. Our results revealed a robust (P < 0.0001) association between low-activity MAOA-uVNTR alleles and violent crime. This association was replicated in the group of Caucasian violent offenders (P < 0.01), but reached only a marginal trend (P = 0.08) in their African American counterparts. While violent crime charges were not associated with CTQ, BIS-11 and BPAQ scores, carriers of low-activity alleles exhibited a mild, yet significant (P < 0.05) increase in BIS-11 total and attentional-impulsiveness scores. In summary, these findings support the role of MAOA gene as a prominent genetic determinant for criminal violence. Further studies are required to confirm these results in larger samples of inmates and evaluate potential interactions between MAOA alleles and environmental vulnerability factors.


Subject(s)
Criminals , Minisatellite Repeats/genetics , Monoamine Oxidase/genetics , Violence , Adolescent , Adult , Aged , Aggression , Analysis of Variance , Case-Control Studies , Gene Frequency , Genotype , Humans , Impulsive Behavior , Male , Middle Aged , Psychometrics , Statistics as Topic , Surveys and Questionnaires , Young Adult
6.
J Obes ; 2014: 983495, 2014.
Article in English | MEDLINE | ID: mdl-25147734

ABSTRACT

Using an ethical lens, this review evaluates two methods of working within patient care and public health: the weight-normative approach (emphasis on weight and weight loss when defining health and well-being) and the weight-inclusive approach (emphasis on viewing health and well-being as multifaceted while directing efforts toward improving health access and reducing weight stigma). Data reveal that the weight-normative approach is not effective for most people because of high rates of weight regain and cycling from weight loss interventions, which are linked to adverse health and well-being. Its predominant focus on weight may also foster stigma in health care and society, and data show that weight stigma is also linked to adverse health and well-being. In contrast, data support a weight-inclusive approach, which is included in models such as Health at Every Size for improving physical (e.g., blood pressure), behavioral (e.g., binge eating), and psychological (e.g., depression) indices, as well as acceptability of public health messages. Therefore, the weight-inclusive approach upholds nonmaleficience and beneficience, whereas the weight-normative approach does not. We offer a theoretical framework that organizes the research included in this review and discuss how it can guide research efforts and help health professionals intervene with their patients and community.


Subject(s)
Diet, Reducing/psychology , Exercise/psychology , Health Behavior , Health Education/methods , Obesity/psychology , Personal Satisfaction , Weight Loss , Health Services Accessibility , Humans , Obesity/prevention & control , Public Health , Social Stigma , Social Support
7.
J Obes ; 2014: 641939, 2014.
Article in English | MEDLINE | ID: mdl-24804086

ABSTRACT

UNLABELLED: Ethnic minorities continue to be disproportionately affected by obesity and are less likely to access healthcare than Caucasians. It is therefore imperative that researchers develop novel methods that will attract these difficult-to-reach groups. The purpose of the present study is to describe characteristics of an urban community sample attracted to a spiritually based, weight loss intervention. METHODS. Thirteen participants enrolled in a pilot version of Spiritual Self-Schema Therapy (3S) applied to disordered eating behavior and obesity. Treatment consisted of 12 one-hour sessions in a group therapy format. At baseline, participants were measured for height and weight and completed a battery of self-report measures. RESULTS: The sample was predominantly African-American and Hispanic and a large percentage of the sample was male. Mean baseline scores of the EDE-Q, YFAS, and the CES-D revealed clinically meaningful levels of eating disordered pathology and depression, respectively. The overall attrition rate was quite low for interventions targeting obesity. DISCUSSION: This application of a spiritually centered intervention seemed to attract and retain a predominantly African-American and Hispanic sample. By incorporating a culturally congruent focus, this approach may have been acceptable to individuals who are traditionally more difficult to reach.


Subject(s)
Cultural Competency , Ethnicity , Feeding and Eating Disorders/therapy , Obesity/therapy , Patient Acceptance of Health Care , Spirituality , Weight Loss , Adult , Black or African American , Body Mass Index , Depression/complications , Depression/therapy , Feeding Behavior , Feeding and Eating Disorders/complications , Female , Hispanic or Latino , Humans , Life Style , Male , Middle Aged , Obesity/complications , Patient Compliance , Pilot Projects , Psychotherapy, Group , Residence Characteristics , Urban Population
8.
Toxicol Appl Pharmacol ; 275(3): 257-64, 2014 Mar 15.
Article in English | MEDLINE | ID: mdl-24518925

ABSTRACT

BACKGROUND: Erionite has similar chemical and physical properties to amphibole asbestos, which induces autoantibodies in mice. Current exposures are occurring in North Dakota due to the use of erionite-contaminated gravel. While erionite is known to cause mesothelioma and other diseases associated with asbestos, there is little known about its effects on the immune system. OBJECTIVES: We performed this study to determine whether erionite evokes autoimmune reactions in mice. METHODS: Bone marrow derived macrophages (BMDM) were used to measure toxicity induced by erionite. Cytokine production by BMDM and splenocytes of C57BL/6 mice was examined by bead arrays and ELISA following exposure to erionite, amphiboles and chrysotile. Wild type C57BL/6 mice were exposed to saline, erionite, amphibole asbestos (Libby 6-Mix) or chrysotile through intratracheal instillations at equal mass (60µg/mouse). Seven months after exposure, sera were examined for anti-nuclear antibodies (ANA) and IL-17. Immunohistochemistry was used to detect immune complex deposition in the kidneys. RESULTS: Erionite and tremolite caused increased cytokine production belonging to the TH17 profile including IL-17, IL-6, TGF-ß, and TNF-α. The frequency of ANA was increased in mice treated with erionite or amphibole compared to saline-treated mice. IL-17 and TNF-α were elevated in the sera of mice treated with erionite. The frequency of immune complex deposition in the kidneys increased from 33% in saline-treated mice to 90% with erionite. CONCLUSIONS: These data demonstrate that both erionite and amphibole asbestos induce autoimmune responses in mice, suggesting a potential for adverse effects in exposed communities.


Subject(s)
Antibodies, Antinuclear/blood , Autoimmunity/drug effects , Interleukin-17/blood , Zeolites/toxicity , Animals , Antigen-Antibody Complex/metabolism , Asbestos, Amphibole/toxicity , Asbestos, Serpentine/toxicity , Biomarkers/blood , Cell Survival/drug effects , Cells, Cultured , Dose-Response Relationship, Drug , Female , Inhalation Exposure , Kidney/drug effects , Kidney/immunology , Kidney/metabolism , Macrophages/drug effects , Macrophages/immunology , Macrophages/metabolism , Mice , Mice, Inbred C57BL , Spleen/drug effects , Spleen/immunology , Spleen/metabolism , Th1 Cells/drug effects , Th1 Cells/immunology , Th1 Cells/metabolism , Th17 Cells/drug effects , Th17 Cells/immunology , Th17 Cells/metabolism , Th2 Cells/drug effects , Th2 Cells/immunology , Th2 Cells/metabolism , Time Factors , Tumor Necrosis Factor-alpha/blood , Up-Regulation
9.
J Immunotoxicol ; 11(3): 283-90, 2014.
Article in English | MEDLINE | ID: mdl-24164284

ABSTRACT

Abstract Exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and increases the risk of systemic autoimmune disease. However, epidemiological studies of chrysotile exposure have not indicated a similar induction of autoimmune responses. To demonstrate this difference in controlled exposures in mice, and to explore possible mechanistic explanations for the difference, C57BL/6 mice were exposed intratracheally to amphibole or chrysotile asbestos, or to saline only. Serum antinuclear antibodies (ANA), antibodies to extractable nuclear antigens (ENA), serum cytokines, and immunoglobulin isotypes were evaluated 8 months after the final treatment. The percentages of lymphocyte sub-sets were determined in the spleen and lungs. The results show that amphibole, but not chrysotile, asbestos increases the frequency of ANA/ENA in mice. Amphibole and chrysotile both increased multiple serum cytokines, but only amphibole increased IL-17. Both fibers decreased IgG1, without significant changes in other immunoglobulin isotypes. Although there were no gross changes in overall percentages of T- and B-cells in the spleen or lung, there was a significant increase in the normally rare populations of suppressor B-cells (CD19(+), CD5(+), CD1d(+)) in both the spleen and lungs of chrysotile-exposed mice. Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice. These data have critical implications in terms of screening and health outcomes of asbestos-exposed populations.


Subject(s)
Asbestosis/diagnosis , Autoimmunity , B-Lymphocytes/drug effects , Lymphocyte Subsets/drug effects , T-Lymphocytes/drug effects , Animals , Antibodies, Antinuclear/blood , Antigens, CD/metabolism , Asbestos, Amphibole/adverse effects , Asbestos, Serpentine/adverse effects , Asbestosis/immunology , Autoimmunity/drug effects , B-Lymphocytes/immunology , Diagnosis, Differential , Humans , Immunoglobulin G/blood , Immunosuppression Therapy , Inhalation Exposure , Interleukin-17/metabolism , Lymphocyte Subsets/immunology , Mass Screening , Mice , Mice, Inbred C57BL , Mineral Fibers/adverse effects , T-Lymphocytes/immunology
10.
Surg Endosc ; 24(10): 2547-55, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20354884

ABSTRACT

INTRODUCTION: Postgastric bypass noninsulinoma hyperinsulinemic pancreatogenous hypoglycemia defines a group of patients with postprandial neuroglycopenic symptoms similar to insulinoma but in many cases more severe. There are few reports of patients with this condition. We describe our surgical experience for the management of this rare condition. METHODS: A retrospective study was performed at St. Vincent Hospital, Indianapolis. Fifteen patients were identified with symptomatic postgastric bypass hypoglycemia for the period 2004-2008. All patients were initially treated with medical therapy for hypoglycemia. Nine patients eventually underwent surgical treatment. The preoperative workup included triple-phase contrast CT scan of the abdomen, endoscopic ultrasound of the pancreas, a 72-h fast followed by a mixed meal test, and calcium-stimulated selective arteriography. Intraoperative pancreatic ultrasound also was performed in all patients. Patients then underwent thorough abdominal exploration, exploration of the entire pancreas, and extended distal pancreatectomy. RESULTS: Nine patients underwent surgery. The mean duration of symptoms was 14 months. The 72-h fast was negative in eight patients (as expected). Triple-phase contrast CT scan of the abdomen was negative in eight patients and showed a cyst in the head of pancreas in one patient. Extended distal (80%) pancreatectomy was performed in all nine patients. The procedure was attempted laparoscopically in eight patients but was converted to open in three. One patient had an open procedure from start to finish. Pathology showed changes compatible with nesidioblastosis with varying degrees of hyperplasia of islets and islet cells. Follow-up ranged from 8-54 (median, 22) months. All patients initially reported marked relief of symptoms. Over time, two patients had complete resolution of symptoms; three patients developed occasional symptoms (once or twice per month), which did not require any medication; two patients developed more frequent symptoms (more than twice per month), which were controlled with medications; and two patients had severe symptoms refractory to medical therapy (calcium channel blockers, diazoxide, octreotide). DISCUSSION: Postprandial hypoglycemia after gastric bypass surgery with endogenous hyperinsulinemia is being increasingly recognized and reported in the literature. Our experience with nine patients is one of the largest. The etiology of this condition is not entirely understood. There may be yet unknown factors involved but increased secretion of glucagon-like peptide 1 and decreased grehlin are being implicated in islet cell hypertrophy. There is no "gold standard" treatment-medical or surgical-but distal pancreatectomy to debulk the hypertrophic islets and islet cells is the main surgical modality in patients with severe symptoms refractory to medical management.


Subject(s)
Gastric Bypass/adverse effects , Hyperinsulinism/etiology , Hypoglycemia/etiology , Laparoscopy , Nesidioblastosis/surgery , Pancreatectomy , Adult , Female , Humans , Hyperinsulinism/surgery , Male , Middle Aged , Nesidioblastosis/etiology , Nesidioblastosis/pathology , Pancreas/pathology , Postprandial Period , Syndrome
11.
J Vasc Surg ; 46(5): 891-6; discussion 896-7, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17980275

ABSTRACT

BACKGROUND: It is commonly assumed that the aortic wall deforms uniformly and has uniform wall thickness about the circumference. The purpose of this study was to evaluate the aortic wall motion and thickness in the infrarenal aortic neck of patients with abdominal aortic aneurysms who were undergoing endovascular repair (EVAR) and to compare the dynamic measurements of intravascular ultrasonography with the static measurements of computed tomographic angiography (CTA). METHODS: A total of 25 patients were evaluated before surgery with CTA and three-dimensional reconstructions on a Vitrea workstation, followed by intraoperative assessment of the proximal aortic neck with intravascular ultrasonography (IVUS) before EVAR. Infrarenal aortic neck dimensions on CTA were obtained at 1-mm intervals, but for the purposes of this study all dimensions on CTA were obtained 1 cm below the lowest renal artery. IVUS analysis of the proximal aortic neck was obtained with a 10-second recorded data loop of aortic wall motion. A Digital Imaging and Communications in Medicine viewer was used to view the recorded loop of aortic movement, and each image was captured and then evaluated with a SCION PCI Frame Grabber to determine aortic dimensions and wall thickness. IVUS diameters (250 measurements of each aorta) were recorded through a full continuous cardiac cycle from the epicenter of the lumen (maintaining the left renal vein in its normal anatomic configuration) in an anteroposterior (AP) direction in the area of greatest wall movement and 90 degrees perpendicular to this direction (lateral movement). RESULTS: There was significant variation in infrarenal aortic wall movement about the circumference, with 1.7 +/- 0.6 mm (range, 0.6-2.7 mm) displacement in the AP direction and 0.9 +/- 0.5 mm (range, 0.3-1.5 mm) displacement in the lateral direction (P < .001). Aortic wall thickness was greater in the region of increased AP wall motion than in the area of lesser lateral wall motion (2.3 +/- 0.6 mm vs 1.2 +/- 0.3 mm; P < .001). There was no difference between the IVUS and CTA aortic neck measurements (25.5 vs 25.6 mm; not significant) during the midpoint of the cardiac cycle of IVUS. However, at peak systole, IVUS recorded a greater diameter than CTA (26.4 vs 25.6 mm; P < .001), and at end-diastole, IVUS recorded a smaller diameter than CTA (24.7 vs 25.6 mm; P = .01). CONCLUSIONS: The infrarenal neck of aortic aneurysms deforms anisotropically during the cardiac cycle. The greatest displacement is in the AP direction and corresponds with a significantly greater wall thickness in this area. The magnitude of cyclic change in aortic diameter can be as high as 11%. Further evaluation of proximal aortic neck wall motion after EVAR is warranted to determine the interaction of various stent designs and the aortic wall.


Subject(s)
Aorta/diagnostic imaging , Aortic Aneurysm, Abdominal/diagnostic imaging , Aortic Aneurysm, Abdominal/pathology , Ultrasonography, Interventional , Aortic Aneurysm, Abdominal/surgery , Blood Vessel Prosthesis Implantation , Humans , Pulsatile Flow , Tomography, X-Ray Computed
13.
Bioinformatics ; 22(19): 2356-63, 2006 Oct 01.
Article in English | MEDLINE | ID: mdl-16882647

ABSTRACT

MOTIVATION: Two important questions for the analysis of gene expression measurements from different sample classes are (1) how to classify samples and (2) how to identify meaningful gene signatures (ranked gene lists) exhibiting the differences between classes and sample subsets. Solutions to both questions have immediate biological and biomedical applications. To achieve optimal classification performance, a suitable combination of classifier and gene selection method needs to be specifically selected for a given dataset. The selected gene signatures can be unstable and the resulting classification accuracy unreliable, particularly when considering different subsets of samples. Both unstable gene signatures and overestimated classification accuracy can impair biological conclusions. METHODS: We address these two issues by repeatedly evaluating the classification performance of all models, i.e. pairwise combinations of various gene selection and classification methods, for random subsets of arrays (sampling). A model score is used to select the most appropriate model for the given dataset. Consensus gene signatures are constructed by extracting those genes frequently selected over many samplings. Sampling additionally permits measurement of the stability of the classification performance for each model, which serves as a measure of model reliability. RESULTS: We analyzed a large gene expression dataset with 78 measurements of four different cartilage sample classes. Classifiers trained on subsets of measurements frequently produce models with highly variable performance. Our approach provides reliable classification performance estimates via sampling. In addition to reliable classification performance, we determined stable consensus signatures (i.e. gene lists) for sample classes. Manual literature screening showed that these genes are highly relevant to our gene expression experiment with osteoarthritic cartilage. We compared our approach to others based on a publicly available dataset on breast cancer. AVAILABILITY: R package at http://www.bio.ifi.lmu.de/~davis/edaprakt


Subject(s)
Algorithms , Gene Expression Profiling/methods , Gene Expression , Neoplasms/metabolism , Oligonucleotide Array Sequence Analysis/methods , Osteoarthritis/metabolism , Proteins/metabolism , Biomarkers/analysis , Cartilage/metabolism , Computer Simulation , Humans , Models, Biological , Models, Statistical , Neoplasms/genetics , Osteoarthritis/genetics , Reproducibility of Results , Sensitivity and Specificity
14.
J Org Chem ; 71(4): 1493-501, 2006 Feb 17.
Article in English | MEDLINE | ID: mdl-16468798

ABSTRACT

Ten acyclic and monocyclic delta,epsilon-unsaturated ketones, with and without methyl substituents on the double bond, underwent halide-terminated Prins (halo-Prins) cyclizations under anhydrous conditions in the presence of Lewis acids. TiCl4, TiBr4, BCl3, and BBr3 promoted syn-selective cyclizations to sterically congested chloro- and bromohydrins, while SnCl4, SnBr4, InCl3, ZrCl4, and several other Lewis acids effected highly anti-selective reactions to furnish the corresponding trans halohydrins. The stronger Lewis acids (TiX4 and BX3) favor the syn process that involves axial delivery of a halide ligand. Competition experiments showed that substitution at the delta carbon (methallyl enones) led to increased rates (40-50-fold), while substitution at the epsilon position (cis and trans crotyl enones) retarded the rate and eroded the selectivity of the cyclizations. The trends in syn vs anti selectivity, reactivity, and effects of different Lewis acidic metal halides are rationalized by competitive reaction pathways proceeding through syn carbocation-halide ion pairs and a higher order transition state that leads to inversion of configuration and formation of trans halohydrins, along with cyclic olefins arising from proton elimination.


Subject(s)
Alcohols/chemical synthesis , Chlorohydrins/chemical synthesis , Ketones/chemistry , Acids , Cyclization , Cycloparaffins , Stereoisomerism
15.
Org Lett ; 6(1): 135-8, 2004 Jan 08.
Article in English | MEDLINE | ID: mdl-14703369

ABSTRACT

[reaction: see text] Two key intermediates of the newly discovered mevalonate-independent pathway for isoprenoid biosynthesis were prepared. Optically pure 2-C-methyl-D-erythritol 4-phosphate and 2,4-cyclodiphosphate were chemically synthesized from D-arabitol using a convenient benzylidene and tert-butyldimethylsilyl protection of polyhydroxylated intermediates. The new scheme offers a straightforward route to analogues and labeled forms.


Subject(s)
Erythritol/analogs & derivatives , Erythritol/chemical synthesis , Sugar Alcohols/chemistry , Sugar Phosphates/chemical synthesis , Models, Chemical , Stereoisomerism , Sugar Alcohols/chemical synthesis
16.
Surg Clin North Am ; 83(5): 1141-61, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14533908

ABSTRACT

So where do things stand in 2003? Laparoscopic herniorrhaphy appears to result in less postoperative pain (acute and chronic) and in a shorter convalescence and an earlier return to work, compared with the open repair. It can be performed safely and with a low recurrence rate. However, it takes longer to do, is more difficult to learn, and costs more, all reasons why it is not more commonly performed. Currently, laparoscopic herniorrhaphy accounts for 15% to 20% of hernia operations in America and around the world. Who can blame the surgeon in a community practice for opting for the open mesh repair, operating on familiar anatomy, and using familiar techniques? Nevertheless, with efforts to cut costs by eliminating disposable equipment and honing skills to decrease operating time, laparoscopic herniorrhaphy will probably continue to be a contender, especially for the younger patient who wants to return to work quickly and for patients with bilateral and recurrent hernias. It is arguable that surgeons should possess skill in both open and laparoscopic techniques and should know the indications for each--some hernias are best repaired laparoscopically. That said, laparoscopic herniorrhaphy will most likely be performed by those with a special interest and proficiency in the technique. At the least, the laparoscopic revolution and laparoscopic hernia repair have helped elevate the study of hernia anatomy and herniorrhaphy to a position it deserves and this has made us all better hernia surgeons. What was once the stepchild of general surgery now occupies a more prominent and respectable place. With the continuing efforts of dedicated, energetic investigators, we should continue to see advances in the safe and effective repair of this most common of surgical maladies.


Subject(s)
Digestive System Surgical Procedures/methods , Hernia, Inguinal/surgery , Digestive System Surgical Procedures/economics , Humans , Intraoperative Complications , Laparoscopy , Meta-Analysis as Topic , Postoperative Complications , Randomized Controlled Trials as Topic , Recurrence , Surgical Mesh , Treatment Outcome
17.
J Org Chem ; 68(18): 6935-43, 2003 Sep 05.
Article in English | MEDLINE | ID: mdl-12946133

ABSTRACT

A total synthesis of the novel silphinane sesquiterpene alcohol (+/-)-cameroonanol (6-OH) from bicyclic enone 10 was accomplished by conjugate addition of crotylsilane, photochemical hydrobromination, intramolecular alkylation, and hydride reduction. The stereoisomers cameroonan-7beta-ol (18-OH) and 9-epicamerooonanols (19 and 20) were separated from isomer mixtures and the 9-desmethylcameroonanols (21-OH and 22-OH) were obtained by similar means. Solvolysis of 6-OMs and 18-OMs effected skeletal rearrangements to (+/-)-silphiperfol-6-ene (5), (+/-)-prenopsanol (7) and (+/-)-nopsanol (8), and (+/-)-silphiperfolan-7beta-ol (9) in parallel with biogenetic schemes proposed for these naturally occurring sesquiterpenes. The nor analogues 21-OMs and 22-OMs underwent solvolytic rearrangments to a similar set of nor products. The increase in solvolytic rates for the 7beta-mesylates 18-OMs and 22-OMs in comparison to the 7alpha epimers is attributed to concerted antiperiplanar Wagner-Meerwein rearrangements to the prenopsyl and norprenopsyl carbocations. Further analysis of the kinetic data and comparisons with solvolysis rates for the structurally related silphin-1beta-yl and silphin-1alpha-yl mesylates (28 and 29) are presented. The rearrangements observed afford chemical precedent for the biogenetic pathways in the literature for these silphinane sesquiterpenes.


Subject(s)
Sesquiterpenes/chemistry , Sesquiterpenes/chemical synthesis , Chromatography, High Pressure Liquid , Indicators and Reagents , Kinetics , Magnetic Resonance Spectroscopy , Mass Spectrometry , Oils, Volatile/chemistry , Plants/chemistry , Stereoisomerism
18.
J Org Chem ; 68(1): 75-82, 2003 Jan 10.
Article in English | MEDLINE | ID: mdl-12515464

ABSTRACT

The regioisomer ratios (3 degrees,2 degrees /2 degrees,3 degrees ), and in some cases the stereochemistry, of vicinal azidohydrins formed in reactions of 11 trisubstituted terpene epoxides with Et(2)AlN(3) in toluene are reported. The more highly substituted azide usually predominated (3 degrees,2 degrees /2 degrees,3 degrees ratios >or= 40:1 to 2.5-1) in accord with a Markovnikov orientation and an S(N)1-like transition state. Reversed regioisomer ratios were observed with 6,7-epoxygeranyl acetate (1:2.5) and cis-1,2-epoxylimonene (1:3.3 to 1:10). The tertiary azido diols from 2,3-epoxygeraniol, 2,3-epoxyfarnesol, and 2,3-epoxynerol were formed as single isomers with inversion of configuration at C3 (>or= 35-40:1 for the C(10) azido diols). The regioselectivity was affected by the presence and proximity of oxy functional groups on the epoxide substrate (OH, OAc, and OSi-tBuMe(2)), the equivalents of Et(2)AlN(3), and additives (EtOAc or EtOH). The results and trends are rationalized by consideration of the structural and stereoelectronic characteristics of proposed diethylaluminum epoxonium ion intermediates and transition states, together with the nucleophilicity of the azide donor. Six of the 3 degrees,2 degrees azidohydrins were converted to the corresponding aziridines by primary-selective silylations of four azido diols, mesylations, and reductive cyclizations with LiAlH(4).


Subject(s)
Azides/chemistry , Aziridines/chemical synthesis , Epoxy Compounds/chemical synthesis , Silanes/chemical synthesis , Terpenes/chemistry , Azides/chemical synthesis , Catalysis , Cyclization , Epoxy Compounds/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Stereoisomerism
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