摘要:

The chemical attachment of poly(ethylene glycol) [PEG] to therapeutic proteins produces several benefits, including enhanced plasma half-life, lower toxicity, and increased drug stability and solubility. In certain instances, pegylation of a protein can increase its therapeutic efficacy by reducing the ability of the immune system to detect and mount an attack on the compound.A PEG-protein conjugate is formed by first activating the PEG moiety so that it will react with, and couple to, the protein. PEG moieties vary considerably in molecular weight and conformation, with the early moieties (monofunctional PEGs; mPEGs) being linear with molecular weights of 12kD or less, and later moieties being of increased molecular weights. PEG2, a recent innovation in PEG technology, involves the coupling of a 30kD (or less) mPEG to lysine that is further reacted to form a branched structure that behaves like a linear mPEG of much larger molecular weight. These compounds are pH and temperature stable, and this factor along with the large molecular weight may account for the restricted volume of distribution seen with drugs utilising these reagents.Three PEG-protein conjugates are currently approved for clinical use in the US, with more under clinical development. Pegademase is used in the treatment of severe combined immunodeficiency disease, pegaspargase for the treatment of various leukaemias, and pegylated interferon-α for chronic hepatitis C virus infections. As illustrated in the case of the 2 pegylated interferon-αs, all pegylated proteins are not equal. The choice of PEG reagent and coupling chemistry is critical to the properties of the PEG-protein conjugate, with the molecular weight of the moiety affecting its rate and route of clearance from the body, and coupling chemistry affecting the strength of the covalent attachment of PEG to therapeutic protein.

ISSN:1173-8804    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

Cutaneous T-cell lymphoma (CTCL) is most often a skin-infiltrating malignancy of clonal CD4+ T-cells. Therapy is based on staging and the likelihood of progression. Biological response modifiers and chemotherapeutic agents are used to preserve the integrity of the host antitumour response while selectively targeting the malignant cells. The biological response-modifying treatment options currently used to treat CTCL are bexarotene, denileukin diftitox, interferon-α, interferon-γ and interleukin-12, as well as extracorporeal photopheresis and phototherapy. A combination therapy approach maximises response in patients with advanced CTCL. Biological response modifiers in combination with photopheresis are used for patients with the leukaemic phase of the disease. Among the majority of patients with advanced stage disease so treated, immune response augmentation appears to prolong survival. Future areas of research should assess not only survival and optimal treatment combinations, but also quality of life during the treatment period.

ISSN:1173-8804    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

The development of cancer involves the accumulation of genetic changes. Over the past decade there has a been spectacular advance in the knowledge of the genetic basis of cancer, mainly as a result of the rapid progression of molecular technology. Pancreatic cancer is one of the most lethal cancers. Conventional therapeutic approaches have not had much impact on the course of this aggressive neoplasm. Knowledge of the molecular biology of pancreatic cancer has grown rapidly. Genetic alterations in pancreatic cancer include oncogene mutations (most commonlyK-rasmutations), and tumour suppressor gene alterations (mainlyp53, p16, DCC, etc.). These advances have potential implications for the management of this deadly disease. Identification of a hereditary genetic predisposition to pancreatic cancer has led to the formation of pancreatic cancer registries around the world, with voluntary screening of patients and siblings for the hereditary genetic defect. Asymptomatic population screening remains unrealistic, but the recognition of subpopulations at increased risk from pancreatic cancer, along with novel and sensitive detection techniques, means that targeted population screening is a step closer. Intensive research is performed in specialist laboratories to improve the diagnostic approach in patients with pancreatic cancer. The use of such molecular diagnostic methods is likely to expand. Molecular biology may also have a great impact on the treatment of pancreatic cancer, and many therapeutic approaches are being evaluated in clinical trials, including gene replacement therapy, genetic prodrug activation therapy, antisense immunology and peptide technology. The ‘molecular age’ has the promise of delivering still better results. This review summarises recent data relating to the molecular biology of pancreatic cancer, with emphasis on features that may be of clinical significance for diagnosis and/or therapy.

ISSN:1173-8804    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

Allergic rhinitis (AR) is the most common chronic condition in children and is estimated to affect up to 40% of all children. It is usually diagnosed by the age of 6 years. The major impact in children is due to co-morbidity of sinusitis, otitis media with effusion, and bronchial asthma. AR also has profound effects on school absenteeism, performance and quality of life.Pharmacotherapy for AR should be based on the severity and duration of signs and symptoms. For mild, intermittent symptoms lasting a few hours to a few days, an oral second-generation antihistamine should be used on an as-needed basis. This is preferable to a less expensive first-generation antihistamine because of the effect of the latter on sedation and cognition. Four second-generation antihistamines are currently available for children under 12 years of age: cetirizine, loratadine, fexofenadine and azelastine nasal spray; each has been found to be well tolerated and effective. There are no clearcut advantages to distinguish these antihistamines, although for children under 5 years of age, only cetirizine and loratadine are approved. Other agents include pseudoephedrine, an oral vasoconstrictor, for nasal congestion, and the anticholinergic nasal spray ipratropium bromide for rhinorrhoea. Sodium cromoglycate, a mast cell stabiliser nasal spray, may also be useful in this population.For patients with more persistent, severe symptoms, intranasal corticosteroids are indicated, although one might consider azelastine nasal spray, which has anti- inflammatory activity in addition to its antihistamine effect. With the exception of fluticasone propionate for children aged 4 years and older, and mometasone furoate for those aged 3 years and older, the other intranasal corticosteroids including beclomethasone dipropionate, triamcinolone, flunisolide and budesonide are approved for children aged 6 years and older. All are effective, so a major consideration would be cost and safety. For short term therapy of 1 to 2 months, the first-generation intranasal corticosteroids (beclomethasone dipropionate, triamcinolone, budesonide and flunisolide) could be used, and mometasone furoate and fluticasone propionate could be considered for longer-term treatment. Although somewhat more costly, these second-generation drugs have lower bioavailability and thus would have a better safety profile.In patients not responding to the above programme or who require continuous medication, identification of specific triggers by an allergist can allow for specific avoidance measures and/or immunotherapy to decrease the allergic component and increase the effectiveness of the pharmacological regimen.

ISSN:1173-8804    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

The mechanisms of action of silymarin involve different biochemical events, such as the stimulation of the synthetic rate of ribosomal RNA (rRNA) species through stimulation of polymerase I and rRNA transcription, protecting the cell membrane from radical-induced damage and blockage of the uptake of toxins such as α-amanitin.Studies in patients with liver disease have shown that silymarin increases superoxide dismutase (SOD) activity of lymphocytes and erythrocytes, as well as the expression of SOD in lymphocytes. Silymarin has also been shown to increase patient serum levels of glutathione and glutathione peroxidase.Silybin 20 to 48 mg/kg/day has shown promise as a clinical antidote to acuteAmanita(deathcap mushroom) poisoning.Primary efficacy data from 3 trials which examined the therapeutic potential of silymarin in patients with cirrhosis, and included patient survival as an end-point, demonstrated that silymarin had no significant beneficial effect on patient mortality. However, upon subanalysis, silymarin 420 mg/day had a significantly beneficial effect on patient survival rate (compared with patients receiving placebo) in 1 randomised, double-blind trial in patients with alcoholic cirrhosis.Silymarin 420 mg/day was also shown to improve indices of liver function [AST, ALT, γ-glutamyl transferase and bilirubin] in patients with liver disease of various aetiology, including those exposed to toxic levels of toluene or xylene; however, it was largely ineffective in patients with viral hepatitis.Reports of adverse events while receiving silymarin therapy are rare. However, there have been accounts of nausea, epigastric discomfort, arthralgia, pruritus, headache and urticaria. Silymarin has also been reported to have possibly caused a mild laxative effect.ConclusionThe antioxidant properties of silymarin (a mixture of at least 4 closely related flavonolignans, 60 to 70% of which is a mixture of 2 diastereomers of silybin) have been demonstratedin vitroand in animal and human studies. However, studies evaluating relevant health outcomes associated with these properties are lacking. Although silymarin has low oral absorption, oral dosages of 420 mg/day have shown some therapeutic potential, with good tolerability, in the treatment of alcoholic cirrhosis. Moreover, silybin 20 to 48 mg/kg/day has shown promise as an antidote for acute mushroom poisoning byAmanita phalloides; however, further studies paying attention to the amount of ingested mushroom and time elapsed before administration of treatment are needed to clarify its role in this indication. Studies in patients with the early onset of liver disease may demonstrate the liver regeneration properties that silymarin is promoted as possessing.

ISSN:1173-8804    

出版商:ADIS    

年代:2001

数据来源: ADIS