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Modified oligonucleotides: synthesis and strategy for users.

Synthetic oligonucleotide analogs have greatly aided our understanding of several biochemical processes. Efficient solid-phase and enzyme-assisted synthetic methods and the availability of modified base analogs have added to the utility of such oligonucleotides. In this review, we discuss the applications of synthetic oligonucleotides that contain backbone, base, and sugar modifications to investigate the mechanism and stereochemical aspects of biochemical reactions. We also discuss interference mapping of nucleic acid-protein interactions; spectroscopic analysis of biochemical reactions and nucleic acid structures; and nucleic acid cross-linking studies. The automation of oligonucleotide synthesis, the development of versatile phosphoramidite reagents, and efficient scale-up have expanded the application of modified oligonucleotides to diverse areas of fundamental and applied biological research. Numerous reports have covered oligonucleotides for which modifications have been made of the phosphodiester backbone, of the purine and pyrimidine heterocyclic bases, and of the sugar moiety; these modifications serve as structural and mechanistic probes. In this chapter, we review the range, scope, and practical utility of such chemically modified oligonucleotides. Because of space limitations, we discuss only those oligonucleotides that contain phosphate and phosphate analogs as internucleotidic linkages.

Deoxyribose↗

Transition metal-catalyzed carbon-carbon bond activation.

This tutorial review deals with recent developments in the activation of C-C bonds in organic molecules that have been catalyzed by transition metal complexes. Many chemists have devised a variety of strategies for C-C bond activation and significant progress has been made in this field over the past few decades. However, there remain only a few examples of the catalytic activation of C-C bonds, in spite of the potential use in organic synthesis, and most of the previously published reviews have dwelt mainly on the stoichiometric reactions. Consequently, this review will focus mainly on the catalytic reaction of C-C bond cleavage by homogeneous transition metal catalysts. The contents include cleavage of C-C bonds in strained and unstrained molecules, and cleavage of multiple C-C bonds such as C[triple bond]C triple bonds in alkynes. Multiple bond metathesis and heterogeneous systems are beyond the scope of this review, though they are also fascinating areas of C-C bond activation. In this review, the strategies and tactics for C-C bond activation will be explained.

Alkynes↗

Alternative surgical procedures for primary rectal carcinoma.

This review summarizes the recent literature on alternative surgical procedures for treating rectal carcinoma. After a brief examination of publications on preoperative staging, current reports on alternative surgical procedures, from local excision to anterior resection and extended resection, are discussed. Although radiotherapy and chemotherapy are assuming increasingly prominent roles in the management of rectal carcinoma, detailed examination of these therapies is beyond the scope of this review.

Anal Canal↗

Progress in 7-deazapurine - pyrrolo[2,3-d]pyrimidine - ribonucleoside synthesis.

This review reports on the synthesis of 7-deazapurine ribonucleosides, including C-nucleosides, 2'-C-methyl derivatives and L-enantiomers. It covers the various aspects of convergent nucleoside synthesis such as the Schiff base procedure, the fusion reaction, the metal salt procedures, the Silyl-Hilbert-Johnson reaction, and the nucleobase anion glycosylation. The review discusses the scope and limitations of glycosylation reactions performed on 7-deazapurines. Peracylated ribose derivatives were now employed in the glycosylation, which overcome difficulties reported earlier.

Purines↗

Regarding: Valero V, Buzdar AU, Hortobagyi GN. "Locally Advanced Breast Cancer," The Oncologist 1996;1:8-17.

To the Editors: I read with interest Valero et al.'s review showing a lack of any increased cure rate over surgery from use of neoadjuvant combination therapy for locally advanced breast cancer, although a definite gain from breast conservation. Missing was any mention of hormone therapy [1] despite some of the best neoadjuvant results being from the use of Tamoxifen® in the elderly [2]. Interestingly, the highest complete remission rate in Valero et al.'s review (52%) was in a regimen including Tamoxifen® [3]. In addition, Bartlett et al. have reported that hormone therapy is superior to chemotherapy as adjuvant in estrogen receptor-positive tumors [4]. With new data from the study of radiotherapy demonstrating prostate tumor cell kill to be far higher when radiation treatment follows hormone therapy rather than when given concurrently or after therapy [5], there is a need for studies to investigate whether the same applies to hormone therapy when combined with chemotherapy in breast cancer. Further support for this comes from the latest overview of the effect of menstrual cycle timing and breast cancer surgery. The greatest gain from operating on premenopausal women occurs when the operation takes place during the progestergenic phase of the menstrual cycle, particularly in advanced node-positive patients and those with high levels of progesterone pre-op attributed to high survival [6]. With increasing recognition that trauma-induced cytokine release can be a factor in tumor acceleration [7], there is a case to consider hormones followed by chemotherapy plus radiation before any major surgical interference [1], most particularly in the rare subgroup of poor-risk tumors arising during pregnancy [8]. AUTHORS' RESPONSE: We appreciate the comments of Professor Oliver regarding our review. It has been recognized for decades that breast cancer is a systemic disease. Regional and distant micro- metastases occur early, and are part of the natural history of this illness. Adjuvant chemotherapy is an integral part of the curative management of patients with primary breast cancer, including locally advanced breast cancer (LABC). The benefit derived from this therapeutic approach is well documented, and persists beyond 10 years of follow-up [1, 2]. While we recognize the paucity of studies in direct support of this statement in patients with operable LABC, a few randomized trials have been completed and published [3, 4], and the world overview of randomized trials also demonstrated this benefit [1, 2]. Several randomized studies are under way to assess the relative efficacy of primary (or neoadjuvant) versus adjuvant chemotherapy in patients with early breast cancer, as well as operable LABC. For patients with inoperable LABC the window of opportunity to perform randomized trials with local therapy only as a control arm was lost many years ago. However, the results of phase II trials compare favorably with outcomes of historical control series. We agree that adjuvant hormonal therapy is also an integral part of optimal management of selected patients with LABC (those >50 years old, and with estrogen receptor-positive tumors). The world overview demonstrated an additive effect in women treated with both systemic modalities. Therefore, for this high-risk group of patients, combined hormone and chemotherapy for those who present with hormone-responsive breast cancer might be the treatment of choice. On the other hand, the role of neoadjuvant hormonal therapy alone remains to be defined. When we last reviewed this issue [5], only limited data were available, and the results did not appear superior to local treatments without systemic therapy. We (and others) are prospectively assessing the role of neoadjuvant tamoxifen in selected patients with LABC (those who are elderly and those patients unfit for chemotherapy). Professor Oliver's comments about other important areas in breast cancer research were beyond the scope of our review.

Journal Article↗

Methods of hydration in palliative care patients.

A strong and often polarized debate has taken place during recent years concerning the consequences of dehydration in the terminally ill patient. When a patient has a severely restricted oral intake or is found to be dehydrated, the decision to administer fluids should be individualized and made on the basis of a careful assessment that considers problems related to dehydration, potential risks and benefits of fluid replacement, and patients' and families' wishes. This review discusses the assessment of hydration status in the terminal cancer patient and the options for fluid administration in the cases where evaluation of the patients' condition has led to this indication. These include different modes of hypodermoclysis, intravenous hydration, use of the nasogastric route, and proctoclysis. Arguments for and against rehydration have been previously addressed by other authors and fall outside the scope of this review.

Dehydration↗

Application of in-situ hybridization techniques to study human preimplantation embryos: a review.

Although the first in-situ hybridization (ISH) experiments were performed more than two decades ago, it was not until 1987 that the technique was implemented in the study of preimplantation. Since then, several groups have explored the feasibility of using the ISH technique as a diagnostic tool to study the genomic constitution of human preimplantation embryos. Though a fair number of such ISH studies have been published and unravelling of the embryos' genomic secrets proceeds with great strides, there are still many challenges in this area of research. The scope of this review is to outline the research and diagnostic applications of single and multicolour (fluorescence) ISH to study the chromosomal content of human preimplantation embryos and to discuss the implications for human preimplantation genetic diagnosis. Current hybridization techniques are being discussed, including the capabilities and pitfalls of this approach when applied to human preimplantation embryos. Finally, future perspectives for the ISH technique in studying the genomic constitution of preimplantation embryos are reviewed.

Chromosome Aberrations↗

Utility of brain natriuretic peptide (BNP) measurement in cardiovascular disease.

Cardiac failure is a prevalent and costly condition in Western society. The ageing of the population, together with current medical options which improve, rather than eradicate heart failure, lead to the projection that this problem will increase substantially in the foreseeable future. The availability of a simple test to assist the diagnosis and effective management of heart failure would greatly assist the clinical approach to this problem. This review examines the physiological basis for the measurement of natriuretic peptides as markers of the presence or risk of heart failure. It considers its use in the hospital and non-hospital setting and examines the cost-effectiveness of current assays. It is possible that in future natriuretic peptides may offer a form of treatment for heart failure, but this is beyond the scope of this review. Nevertheless, the review highlights the potential benefits of this group of tests in the management of heart failure.

Biomarkers↗

Cardiocutaneous syndromes and associations.

UNLABELLED: Multiple cardiocutaneous syndromes and associations are described and reviewed with the emphasis on syndromes that are likely first to be recognized by dermatologists, thereby creating awareness of potential significant cardiovascular disease. Multiple lentigines syndrome, the Carney complex, and Marfan syndrome are examples of syndromes with embryologic and genetic overlap between the cardiac and cutaneous systems. An exhaustive, complete listing of every known disorder or syndrome with combined cardiac and cutaneous findings is beyond the scope of this review. However, all the common associations, both acquired and inherited, including connective tissue, autoimmune, infiltrative, and endocrine disorders are discussed. Because of the serious nature of many of the cardiac defects, early recognition of these conditions by dermatologists and appropriate referrals to colleagues is essential; in addition, when appropriate, genetic counseling is recommended for known heritable disorders. LEARNING OBJECTIVE: At the conclusion of this learning activity, participants should be familiar with the embryology of the neural crest, specifically the development of melanocytes and the heart with its vessels, leading to shared abnormalities of the two systems; the major syndromes and associations producing both cutaneous changes, especially of the pigment systems, and cardiovascular abnormalities; the role of the dermatologist in recognizing these changes; and the need to be cognizant and alert in helping screen for associated systemic disease.

Cardiovascular Diseases↗

A history of radiation detection instrumentation.

A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

Equipment Design↗

A history of radiation detection instrumentation.

A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

Equipment Design↗

Educating patients with diabetes about cardiovascular disease risk.

In persons with diabetes mellitus, atherosclerosis is increased, develops prematurely, and is associated with an accelerated progression of atherosclerotic changes. More than 55% of deaths from diabetes are from cardiovascular disease. Central to the optimal management of diabetes and the prevention of chronic complications is effective patient education. The necessity of optimal glycemic control in the prevention of long-term diabetes-related complications, particularly microvascular disease, has been a primary focus of diabetes education during the past decade. It has become clear that to prevent cardiovascular disease in persons with diabetes, an increased emphasis on patient education aimed at reducing cardiovascular disease risk factors is essential. This review explores the scope, impact, and prevention of diabetes-related cardiovascular disease, focusing on integration of cardiovascular disease risk reduction during patient teaching and education programs.

Cardiovascular Diseases↗

Carcinogenic heterocyclic amines in model systems and cooked foods: a review on formation, occurrence and intake.

Frying or grilling of meat and fish products may generate low ppb levels of mutagenic/carcinogenic heterocyclic amines (HAs). Many heterocyclic amines are formed via the Maillard reaction from creatine, free amino acids and monosaccharides; compounds naturally occurring in protein-rich foods of animal origin. The formation and yield of HAs are dependent on physical parameters, such as cooking temperature and time, cooking technique and equipment, heat and mass transport, and on chemical parameters, especially the precursors to HAs. This paper reviews the current knowledge on the formation of HAs in cooked foods and model systems, and summarizes data on the content of HAs in various cooked foods, and estimates of the dietary intake of HAs. It should be noted that the presence of carcinogens of other types in food (e.g. nitrosamines, aromatic amines, cholesterol oxide products) and that their generation during frying and grilling are outside the scope of this review.

Amines↗

Examining the relationship between obesity and prostate cancer.

Affecting over 30% of the population, obesity is an epidemic in the United States and is associated with multiple chronic medical problems. Obesity is also associated with numerous hormonal changes, many of which have been implicated in prostate cancer development and progression. Although, on the whole, controversy exists over whether obesity increases the risk of prostate cancer, data strongly suggest that obesity is a significant risk factor for prostate cancer death. In this review, we discuss the epidemiologic data surrounding obesity and prostate cancer. We also discuss some of the sequelae of obesity and their relationships with prostate cancer, including alterations in insulin, the insulin-like growth factor axis, and leptin levels; insulin resistance; and diabetes. Although a complete overview of all the various dietary and lifestyle factors that are associated with obesity and prostate cancer risk is beyond the scope of this review, we discuss data concerning the relationship between a high-fat diet and prostate cancer.

Journal Article↗

Forensic psychiatry: contemporary scope, challenges and controversies.

Forensic psychiatry is the branch of psychiatry that deals with issues arising in the interface between psychiatry and the law, and with the flow of mentally disordered offenders along a continuum of social systems. Modern forensic psychiatry has benefited from four key developments: the evolution in the understanding and appreciation of the relationship between mental illness and criminality; the evolution of the legal tests to define legal insanity; the new methodologies for the treatment of mental conditions providing alternatives to custodial care; and the changes in attitudes and perceptions of mental illness among the public. This paper reviews the current scope of forensic psychiatry and the ethical dilemmas that this subspecialty is facing worldwide.

Journal Article↗

Propentofylline for dementia.

BACKGROUND: Propentofylline is a novel therapeutic agent for dementia that readily crosses the blood-brain barrier and acts by blocking the uptake of adenosine and inhibiting the enzyme phosphodiesterase. In vitro and in vivo its mechanism of action appears to be twofold; it inhibits the production of free radicals and reduces the activation of microglial cells. It therefore interacts with the inflammatory processes that are thought to contribute to dementia, and given its mechanism of action is a possible disease modifying agent rather than a purely symptomatic treatment. OBJECTIVES: To determine the clinical efficacy and safety of propentofylline for people with dementia. SEARCH STRATEGY: The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 5 February 2003. Aventis, the manufacturing pharmaceutical company, was asked for data from unpublished studies but declined to enter into correspondence. SELECTION CRITERIA: Unconfounded double-blind randomized controlled trials of propentofylline compared with a placebo or another treatment group. DATA COLLECTION AND ANALYSIS: There were detailed reports of only four of the nine included studies. The efficacy of propentofylline was reviewed for undifferentiated dementia as there were not enough data to attempt a subgroup analysis for the types of dementia. MAIN RESULTS: The following statistically significant treatment effects in favour of propentofylline are reported. Cognition at 3, 6 and 12 months including MMSE at 12 months. [MD 1.2, 95%CI 0.12 to 2.28, P=0.03] Severity of dementia at 3, 6 and 12 months including CGI at 12 months [MD -0.21, 95%CI -0.39 to -0.03, P=0.03]. Activities of Daily Living (NAB) at 6 and 12 months [MD -1.20, 95%CI -2.22 to -0.18, P=0.02]. Global Assessment (CGI) at 3 months [MD -0.48, 95% CI -0.75 to -0.21, P=0.0006], but not at later times. Tolerability There were minimal data on adverse effects and drop-outs. There were a statistically significant treatment effects in favour of placebo at 12 months, for the number of dropouts, [OR=1.43, 95%CI 1.04 to 1.90, P=0.03]. REVIEWER'S CONCLUSIONS: There is limited evidence that propentofylline might benefit cognition, global function and activities of daily living of people with Alzheimer's disease and/or vascular dementia. The meta-analyses reported here are far from satisfactory as a summary of the efficacy of propentofylline, considering the unpublished information on another 1200 patients in randomized trials that exists. Unfortunately Aventis has been unwilling to correspond with the authors, significantly limiting the scope of this review.

Aged↗

The solvent dependence of enzyme specificity.

The discovery that enzymes possess catalytic activity in organic solvents has made it possible to address the question of the influence of the reaction medium on enzymatic specificity. Recently, the substrate specificity, enantioselectivity, prochiral selectivity, regioselectivity, and chemoselectivity of enzymes have been found to dramatically depend on the nature of the solvent. This review discusses the scope, possible mechanisms, and implications of this phenomenon, as well as directions of future research in the area.

Animals↗

Pharmacologic management of psychosis in dementia.

Significant consequences of untreated psychosis in patients with dementia have led clinicians to seek improved therapeutic options. This review presents the scope of the problem, discusses some of the underlying neurobiology, and highlights the evidence for appropriate therapies. A range of potentially effective pharmacologic therapies is available and is discussed.

Aged↗