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23. Porphyria Metabolites Enzymes Glycine + Succinyl CoA 5-ALA Haem, . Globin. . Apoprotein. Haemoglobin. Respiratory pigments. Acute porphyrias. NonAcute, or Cutaneous porphyrias. Porphyrins deposited in upper epidermis. http://www.users.dircon.co.uk/~rosebud/anaesthesia/porphyrias.html

Contents Acute porphyrias Common features Acute Intermittent Porphyria Plumboporphyria ... Drugs that precipitate porphyria Acute vs Non acute Cutaneous vs non cutaneous Other disease producing porphyrinuria Lead poisoning Fe deficiency anaemia Alcohol abuse All Autosomal dominant except congenital porphyria (rare) - recessive PCT may be acquired Acute attacks precipitated by: Drugs Alcohol Prevalence Europe/N America 1/10 000 White South Africa 1/400 Severe in homozygotes Porphyria Metabolites Enzymes Glycine + Succinyl CoA 5-ALA Plumboprophyria ALA dehydratase Porphobilinogen PBG in urine Acute Intermittant porphyria PBG deaminase Hydroxymethylbilane Uropphyrinogen I Congenital Porphria Uroporphyrinogen cosythetase Uroporpyrinogen III Porphyria cutanea tarda Uroporpyrinongen decarboxylase Coproporrphyrinogen III Hereditary coprophyria Coproporphyrinogen oxidase Protoporphyrinogen IX Variegate porphyria Protoporhyrinogen oxidase Protoporphyrin IX . Iron (Fe ++) Erythropoeitic porphyria Ferrochelatase Haem . Globin . Apoprotein Haemoglobin Respiratory pigments Acute porphyrias Common features: Abdominal Neuropsychiatric Neurovisceral 5-ALA + PBG in urine Urine darkens on light exposure Acute Intermittent Porphyria Most severe Deficiency of PBG deaminase GI symptoms in 95% 70% colicky abdominal pain and tenderness

24. Porphyrias | Ahealthyme.com porphyrias Barrett, Julia. Definition. The porphyrias precursor. Thissituation is the main characteristic of the porphyrias. Owing http://www.ahealthyme.com/article/gale/100083892

Search AHealthyMe! Personalize AHealthyMe! Sign up for our Newsletter! Porphyrias Barrett, Julia Definition The porphyrias are disorders in which the body produces too much porphyrin and insufficient heme (an iron-containing nonprotein portion of the hemoglobin molecule). Porphyrin is a foundation structure for heme and certain enzymes. Excess porphyrins are excreted as waste in the urine and stool. Overproduction and overexcretion of porphyrins causes low, unhealthy levels of heme and certain important enzymes, creating various physical symptoms. Description Biosynthesis of heme is a multistep process that begins with simple molecules and ends with a large, complex heme molecule. Each step of the chemical pathway is directed by its own task-specific protein, called an enzyme. As a heme precursor molecule moves through each step, an enzyme modifies the precursor in some way. If a precursor molecule is not modified, it cannot proceed to the next step, causing a buildup of that specific precursor. This situation is the main characteristic of the porphyrias. Owing to a defect in one of the enzymes of the heme biosynthesis pathway, protoporphyrins or porphyrins (heme precursors) are prevented from proceeding further along the pathway. These precursors accumulate at the stage of the enzyme defect causing an array of physical symptoms in an affected person. Specific symptoms depend on the point at which heme biosynthesis is blocked and which precursors accumulate. In general, the porphyrias primarily affect the skin and the nervous system. Symptoms can be debilitating or life threatening in some cases. Porphyria is most commonly an inherited condition. It can also, however, be acquired after exposure to poisonous substances.

25. Porphyrias | Ahealthyme.com You are here Home Health A to Z porphyrias. porphyrias. Barrett, Julia. Theporphyrias. In Williams Hematology, edited by Ernest Beutler, et al. http://www.ahealthyme.com/topic/topic100587325

Search AHealthyMe! Personalize AHealthyMe! Sign up for our Newsletter! You are here: Home Health A to Z Porphyrias Barrett, Julia Below: Definition Description Causes and symptoms Diagnosis ... Resources Definition The porphyrias are disorders in which the body produces too much porphyrin and insufficient heme (an iron-containing nonprotein portion of the hemoglobin molecule). Porphyrin is a foundation structure for heme and certain enzymes. Excess porphyrins are excreted as waste in the urine and stool. Overproduction and overexcretion of porphyrins causes low, unhealthy levels of heme and certain important enzymes, creating various physical symptoms. Description Biosynthesis of heme is a multistep process that begins with simple molecules and ends with a large, complex heme molecule. Each step of the chemical pathway is directed by its own task-specific protein, called an enzyme. As a heme precursor molecule moves through each step, an enzyme modifies the precursor in some way. If a precursor molecule is not modified, it cannot proceed to the next step, causing a buildup of that specific precursor. This situation is the main characteristic of the porphyrias. Owing to a defect in one of the enzymes of the heme biosynthesis pathway, protoporphyrins or porphyrins (heme precursors) are prevented from proceeding further along the pathway. These precursors accumulate at the stage of the enzyme defect causing an array of physical symptoms in an affected person. Specific symptoms depend on the point at which heme biosynthesis is blocked and which precursors accumulate. In general, the porphyrias primarily affect the skin and the nervous system. Symptoms can be debilitating or life threatening in some cases. Porphyria is most commonly an inherited condition. It can also, however, be acquired after exposure to poisonous substances.

26. Porphyrias porphyrias. Definition The porphyrias are a group of rare disordersthat affect heme biosynthesis. Heme is an essential http://www.chclibrary.org/micromed/00061410.html

Main Search Index Definition Description Causes ... Resources Porphyrias Definition The porphyrias are a group of rare disorders that affect heme biosynthesis. Heme is an essential component of hemoglobin as well as many enzymes throughout the body. Description Biosynthesis of heme is a multistep process that starts with simple molecules and ends with a large, complex heme molecule. Each step of the biosynthesis pathway is directed by its own task-specific protein, called an enzyme. As a heme precursor molecule moves through each step, an enzyme modifies it in some way. If the precursor is not modified, it cannot proceed to the next step. This situation is the main characteristic of the porphyrias. Owing to a defect in one of the enzymes of the heme biosynthesis pathway, protoporphyrins or porphyrin (heme precursors) are prevented from proceeding further along the pathway. Instead, precursors accumulate at the stage of the enzyme defect and cause an array of physical symptoms in the affected person. Specific symptoms depend on the point at which heme biosynthesis is blocked and which precursors accumulate. In general, the porphyrias primarily affect the skin and the nervous system. Symptoms can be debilitating or life threatening in some cases. Porphyria is an inherited condition, but it may be acquired after exposure to poisonous substances. Heme Heme is produced in several tissues in the body, but its primary biosynthesis sites are the liver and the bone marrow. Heme synthesis for immature red blood cells, namely the erythroblasts and the reticulocytes, occurs in the bone marrow.

27. The Porphyrias The porphyrias by Shane Greene, Pharm.D. Introduction The porphyrias are a groupof inherited or acquired genetic defects in the heme biosynthetic pathway. http://www.clevelandclinicmeded.com/medical_info/pharmacy/septoct1999/pharm.htm

The Porphyrias by Shane Greene, Pharm.D. Introduction: The porphyrias are a group of inherited or acquired genetic defects in the heme biosynthetic pathway. These defects cause complete or near complete inactivation of the genes encoding for the enzymes that catalyze the transformation of porphyrin precursors. A deficiency in one of these enzymes leads to overproduction and accumulation of these precursors. The specific type of porphyria depends on the location of the accumulation and the enzyme affected. The porphyrias mainly manifest as effects on the nervous system and skin. Classification: The porphyrias are classified as either hepatic or erythropoietic. Hepatic porphyrias have normal red blood cell porphyrin concentrations and present clinically with neurologic symptoms, abdominal pain, neuropathy, and/or psychiatric symptoms. Erythropoietic porphyrias present with an increased concentration of porphyrin within the red blood cells and cutaneous photosensitivity manifestations. Epidemiology: Etiology and Pathogenesis: A different gene encodes each enzyme within the heme biosynthetic pathway. A deficiency in one of the genes is associated with a specific type of porphyria

28. CCHS Clinical Digital Library Disorders. porphyrias Clinical Resources. INFO ) Chapter 346 Theporphyrias Table of contents Heme Biosynthesis Access document; http://cchs-dl.slis.ua.edu/clinical/metabolism/inborn/porphyria.htm

Clinical Resources by Topic: Metabolic Disorders Porphyrias Clinical Resources Emergency Pediatrics Atlases Radiology ... Miscellaneous Resources See also: Genetic Testing Clinical Resources General Genetic Disorders Clinical Resources General Metabolic Disorders Clinical Resources Porphyrias Patient/Family Resources Harrison's Principles of Internal Medicine 15th Ed.-2001: Table of contents Health Sciences Library subscription INFO Chapter 346: The Porphyrias: Table of contents Heme Biosynthesis: Access document Regulation of Heme Biosynthesis: Access document The Hepatic Porphyrias: Access document Introduction: Access document ALA Dehydratase-Deficient Porphyria: Access document Treatment: Access document Acute Intermittent Porphyria: Access document Treatment: Access document Porphyria Cutanea Tarda: Access document Treatment: Access document Hereditary Coproporphyria: Access document Treatment: Access document Variegate Porphyria: Access document Treatment: Access document The Erythropoietic Porphyrias: Access document Introduction: Access document X-Linked Sideroblastic Anemia: Access document Treatment: Access document Congenital Erythropoietic Porphyria: Access document Treatment: Access document Erythropoietic Protoporphyria: Access document Treatment: Access document Hoffman: Hematology: Basic Principles and Practice 3rd Ed.-2000 (MD Consult):

29. 9.8.2 Acute Porphyrias - BNF 9.8.2, Acute porphyrias. The acute porphyrias (acute intermittent porphyria,variegate porphyria, hereditary coproporphyria and 5aminolaevulinic http://bnf.vhn.net/bnf/documents/bnf.1935.html

BNF No. 44 (September 2002) General information and late changes Guidance on prescribing Emergency treatment of poisoning ... Nurse Prescribers' Formulary Acute porphyrias The acute porphyrias (acute intermittent porphyria, variegate porphyria, hereditary coproporphyria and 5-aminolaevulinic acid dehydratase deficiency porphyria) are hereditary disorders of haem biosynthesis; they have a prevalence of about 1 in 10 000 of the population. Great care must be taken when prescribing for patients with acute porphyria since many drugs can induce acute porphyric crises. Since acute porphyrias are hereditary, relatives of affected individuals should be screened and advised about the potential danger of certain drugs. Treatment of serious or life-threatening conditions should not be withheld from patients with acute porphyria. Where there is no safe alternative, urinary porphobilinogen excretion should be measured regularly; if it increases or symptoms occur, the drug can be withdrawn and the acute attack treated. Haem arginate is administered by short intravenous infusion as haem replacement in moderate, severe or unremitting acute porphyria crises.

30. Drugs Unsafe For Use In Acute Porphyrias - BNF Drugs unsafe for use in acute porphyrias The following list contains drugs on theUK market that have been classified as unsafe in porphyria because they have http://bnf.vhn.net/bnf/documents/bnf.1937.html

BNF No. 44 (September 2002) General information and late changes Guidance on prescribing Emergency treatment of poisoning ... Nurse Prescribers' Formulary Drugs unsafe for use in acute porphyrias The following list contains drugs on the UK market that have been classified as unsafe in porphyria because they have been shown to be porphyrinogenic in animals or in vitro , or have been associated with acute attacks in patients. Further information may be obtained from: Welsh Medicines Information Centre University Hospital of Wales Cardiff CF14 4XW Telephone (029) 2074 2979 Note . Quite modest changes in chemical structure can lead to changes in porphyrinogenicity but where possible general statements have been made about groups of drugs; these should be checked first Drug groups (please check first Amphetamines Anabolic Steroids Antidepressants Antihistamines Barbiturates Benzodiazepines Cephalosporins Contraceptives, steroid Diuretics Ergot Derivatives Gold Salts Hormone Replacement Therapy Menopausal Steroids Progestogens Sulphonamides Sulphonylureas Individual Drugs (please check groups above first Alcohol Aluminium-containing Antacids Aminoglutethimide Amiodarone Azapropazone Baclofen Bromocriptine Busulfan Captopril Carbamazepine Carisoprodol Chloral Hydrate Chlorambucil Chloramphenicol Chloroform Ciclosporin Clonidine Cocaine Colistin Cyclophosphamide Cycloserine Danazol Dapsone Dexfenfluramine Dextropropoxyphene Diclofenac Doxycycline Econazole Enflurane Erythromycin Etamsylate Ethionamide Ethosuximide Etomidate Fenfluramine Flucloxacillin

31. Florida State University College Of Medicine Digital Library Disorders. porphyrias Clinical Resources. for. The Merck Manual 17th Ed.1999Table of contents Chapter 14 The porphyrias Table of contents http://fsumed-dl.slis.ua.edu/clinical/metabolism/inborn/porphyria.htm

Clinical Resources by Topic: Metabolic Disorders Porphyrias Clinical Resources Emergency Pediatrics Atlases Radiology ... Miscellaneous Resources See also: Genetic Testing Clinical Resources General Genetic Disorders Clinical Resources General Metabolic Disorders Clinical Resources Porphyrias Patient/Family Resources Harrison's Principles of Internal Medicine 15th Ed.-2001: Table of contents Medical Library subscription INFO Chapter 346: The Porphyrias: Table of contents Heme Biosynthesis: Access document Regulation of Heme Biosynthesis: Access document The Hepatic Porphyrias: Access document Introduction: Access document ALA Dehydratase-Deficient Porphyria: Access document Treatment: Access document Acute Intermittent Porphyria: Access document Treatment: Access document Porphyria Cutanea Tarda: Access document Treatment: Access document Hereditary Coproporphyria: Access document Treatment: Access document Variegate Porphyria: Access document Treatment: Access document The Erythropoietic Porphyrias: Access document Introduction: Access document X-Linked Sideroblastic Anemia: Access document Treatment: Access document Congenital Erythropoietic Porphyria: Access document Treatment: Access document Erythropoietic Protoporphyria: Access document Treatment: Access document Hoffman: Hematology: Basic Principles and Practice 3rd Ed.-2000 (MD Consult):

32. Florida State University College Of Medicine Digital Library Disorders. porphyrias Patient/Family Resources. document. Miscellaneousporphyrias Patient/Family Resources Healthfinder (US DHHS) Homepage http://fsumed-dl.slis.ua.edu/patientinfo/metabolism/inborn/porphyria.htm

Patient/Family Resources by Topic: Metabolic Disorders Porphyrias Patient/Family Resources Spanish Miscellaneous See also: Genetic Testing Patient/Family Resources General Genetic Disorders Patient/Family Resources Porphyrias Clinical Resources National Institute of Diabetes and Digestive and Kidney Diseases: Homepage Kidney Diseases Publications Online: List of documents Porphyrias: Access document MEDLINE plus Medical Encyclopedia: Table of contents Acute Porphyria: English Spanish Hepatic Porphyria: English Spanish Porphyria: English Spanish Merck Manual Home Edition Table of contents Chapter 141. Porphyrias: Access document Spanish MEDLINE plus Medical Encyclopedia: Table of contents Acute Porphyria: English Spanish Hepatic Porphyria: English Spanish Porphyria: English Spanish Miscellaneous Porphyrias Patient/Family Resources Healthfinder (US DHHS): Homepage Genetics: List of documents National Library of Medicine MEDLINE plus Health Topics: Index Porphyria: List of documents Genetic Testing/Counseling: List of documents Genetic Disorders: List of documents YAHOO - Health:Diseases and Conditions:Porphyria Additional Porphyria resources ( These sites have not been reviewed.

33. Porphyrias porphyrias. Definition. The porphyrias are specific precursor. Thissituation is the main characteristic of the porphyrias. Owing http://www.healthatoz.com/healthatoz/Atoz/ency/porphyrias.html

Encyclopedia Index P Home Encyclopedia Encyclopedia Index P Porphyrias Definition The porphyrias are disorders in which the body produces too much porphyrin and insufficient heme (an iron-containing nonprotein portion of the hemoglobin molecule). Porphyrin is a foundation structure for heme and certain enzymes. Excess porphyrins are excreted as waste in the urine and stool. Overproduction and overexcretion of porphyrins causes low, unhealthy levels of heme and certain important enzymes, creating various physical symptoms. Description Biosynthesis of heme is a multistep process that begins with simple molecules and ends with a large, complex heme molecule. Each step of the chemical pathway is directed by its own task-specific protein, called an enzyme. As a heme precursor molecule moves through each step, an enzyme modifies the precursor in some way. If a precursor molecule is not modified, it cannot proceed to the next step, causing a buildup of that specific precursor. This situation is the main characteristic of the porphyrias. Owing to a defect in one of the enzymes of the heme biosynthesis pathway, protoporphyrins or porphyrins (heme precursors) are prevented from proceeding further along the pathway. These precursors accumulate at the stage of the enzyme defect causing an array of physical symptoms in an affected person. Specific symptoms depend on the point at which heme biosynthesis is blocked and which precursors accumulate. In general, the porphyrias primarily affect the skin and the nervous system. Symptoms can be debilitating or life threatening in some cases. Porphyria is most commonly an inherited condition. It can also, however, be acquired after exposure to poisonous substances.

34. Porphyrias At The Charles University, Prague, Czech Republic Welcome to the Experimental porphyrias at the Institute of Pathophysiologyin Prague! Or have you perhaps never heard about porphyrias? http://www.lf1.cuni.cz/~jkri/porphyria.html

Welcome to the Experimental Porphyrias at the Institute of Pathophysiology in Prague! This page provides information on our porphyria-related research to any welcome quest. Porphyria research is a traditional topics at the Institute of Pathophysiology of the First Medical Faculty in Prague, Czech Republic. Please note - we are not the only porphyria - oriented department at the University! First Department of Internal Medicine, headed by Professor Kordac, has done a great, great amount of work. Well, during the communist past, of course... And, undoubtedly, the greatest Czech-born porphyria expert living today is Professor Pavel Martasek, recently back from the B.S.Masters group in Texas - but you sure know him as the Hamburg Porphyrias 1997 organiser. For any comments, please write to Jan Krijt at jkri@lf1.cuni.cz. Or have you perhaps never heard about porphyrias? Then you can visit one of the many www porphyria pages : perhaps the one belonging to Prof. MR Moore . Especially the proceedings of the 1997 Hamburg Porphyria meetig contain right up-to-date information. Also, you can visit our

35. Porphyrias At The Charles University, Prague, Czech Republic The Acute Porphyria Theories. From pathophysiological point of view, theacute porphyrias are perhaps more puzzling than nonacute porphyrias. http://www.lf1.cuni.cz/~jkri/acute.html

The Acute Porphyria Theories From pathophysiological point of view, the acute porphyrias are perhaps more puzzling than nonacute porphyrias. A major clinical complication of an acute attack of porphyria is severe peripheral neuropathy. According to current concepts, the pathophysiology of porphyric attack could be related to: - limited availability of heme in the CNS - limited heme saturation of tryptophan pyrrolase - toxic effects of porphyrins and/or porphyrin precursors on CNS and/or peripheral nerves - limited availability of heme as a cofactor of nitric oxide synthase (nNOS and eNOS) In the course of porphyria research, many experimental porphyrias have been developed, including PBG-DE deficient mice and ferrochelatase deficient mice. At this Institute, we are still using old fashioned in vivo models - animals treated with an inhibitor of heme biosynthesis. It is felt that these models could - in spite of their simple design - still throw some light on the pathophysiology of porphyria. Next, we will present some results obtained in mice treated with a competitive inhibitor of protoporphyrinogen oxidase , which form a basis for our porphyria pathophysiology theory.

36. Porphyrias porphyrias Compiled by Professor Michael Moore. porphyrias http//medic.bgu.ac.ilA brief look at the two major types, the symptoms and an example is given. http://www.medlina.com/porphyrias.htm

Academic Medicine Addiction Aging AIDS-HIV ... Women's Health The Web MEDLINA.com (partial) CDC WHO FDA NIH CATEGORIES Search: All Products Books Magazines Popular Music Classical Music Video DVD Baby Electronics Software Outdoor Living Wireless Phones Keywords: Home Up Nutrition Health Medicine Books Nutrition News ... Malnutrition Porphyrias Water Electrolyte Acid Base Eating Disorders Body Weight Disorders Metabolism Books Porphyrias The American Porphyria Foundation - http://www.enterprise.net Non-profit organization advancing awareness, research, and treatment of Porphyria. Fact sheets and links to related resources. Canadian Porphyria Foundation - http://www.cpf-inc.ca Mission statement, objectives of the organization, newsletters and safe and unsafe drugs. Also: A Guide to Porphyria - a complete booklet of information. Porphyria Page - http://www.uq.edu.au A patient guide for all people with this disorder. Compiled by Professor Michael Moore. Porphyrias - http://medic.bgu.ac.il A brief look at the two major types, the symptoms and an example is given. Acute Intermittent Porphyria Forum - http://members.tripod.com

37. American Porphyria Foundation - The Porphyrias The porphyrias. The information that was on this page is now out ofdate. If you have copies of old versions of this page then please http://www.enterprise.net/apf/overview.html

The Porphyrias The information that was on this page is now out of date. If you have copies of old versions of this page then please delete those copies because the information no longer reflects the latest research. If you have links to this page then please remove those links because this page is no longer being maintained. For more general information on Porphyria, please see the main page of the American Porphyria Foundation

38. NorDx: Test Catalog Special Instructions. Porphyrinogens, Porphyrins, and porphyrias.The porphyrias are emotionally distressful and potentially lethal http://nordx.mmc.org/testcat/procedure.asp?ProcedureID=30

39. NSW PORPHYRIN REFERENCE LABORATORY porphyrias CLINICAL BACKGROUND. The porphyrias are a group of disordersin the haem biosynthetic pathway. They may be the result http://www.cs.nsw.gov.au/csls/RPAH/porphyria/backgroundporphyrias.htm

CSLS HOME PAGE PORPHYRIN UNIT HOME PAGE PORPHYRIN ... LINKS PORPHYRIAS - CLINICAL BACKGROUND The porphyrias are a group of disorders in the haem biosynthetic pathway. They may be the result of inborn errors of metabolism or else due to toxins in the environment. The diagram and porphyria classification shows the haem pathway and lists the types of porphyria, the symptoms expressed, the mode of inheritance and whether the primary lesion is in the liver or in the erythropoietic system. The primary lesion in each porphyria is a reduction rather than a complete absence in one of the enzymes in the pathway. Normally the pathway can cope because of the presence of at least half of the normal enzyme activity. However, under certain conditions, the pathway becomes activated giving rise to a build up of metabolites at the particular enzyme that is deficient. The activity of ALA synthetase however, varies widely because it is the rate controlling enzyme of the pathway. Being an allosteric enzyme, its activity is feedback inhibited by the end-product haem. Moreover, haem can feedback repress the synthesis of ALA synthetase. An acute attack of neurological porphyria may occur if certain drugs are administered to the patient. This acute attack may include abdominal pain, nausea, vomiting, constipation, neuropathies (peripheral and motor) and psychiatric symptoms. Lists of safe and unsafe drugs in patients with acute porphyria are included on pages 11 and 12.

40. Porphyrias porphyrias. 1. CLASSIFICATION. The porphyrias are a heterogeneous groupof either inherited or acquired disorders of haem biosynthesis. http://ruby.med.cuhk.edu.hk/~cpy/lecture/porphyrias.html

Dr C W Lam 2 November 1998 DEPARTMENT OF CHEMICAL PATHOLOGY THE CHINESE UNIVERSITY OF HONG KONG PORPHYRIAS 1. CLASSIFICATION 2. HAEM BIOSYNTHESIS 3. SYMPTOMS AND SIGNS 4. ENZYMIC DEFECTS IN THE HAEM-SYNTHETIC PATHWAY 5. CLINICAL INDICATIONS FOR PERFORMING PORPHYRIN INVESTIGATIONS 6. LABORATORY INVESTIGATION OF THE PORPHYRIAS 7. PORPHYRINURIA 1. CLASSIFICATION The Porphyrias are a heterogeneous group of either inherited or acquired disorders of haem biosynthesis. In these diseases, specific abnormalities of enzymes in the biosynthetic pathway cause generalised clinical abnormalities. They are classified, as shown below, into acute and non-acute porphyria. ACUTE PORPHYRIA ACUTE INTERMITTENT PORPHYRIA (AIP) VARIEGATE PORPHYRIA (VP) HEREDITARY COPROPORPHYRIA (HC) PLUMBOPORPHYRIA NON-ACUTE PORPHYRIA PORPHYRIA CUTANEA TARDA (PCT) ERYTHROPOIETIC PROTOPORPHYRIA (EP) CONGENITAL ERYTHROPOIETIC PORPHYRIA (CEP) 2. Haem Biosynthesis 3. Symptoms and Signs Different stages in haem synthesis are affected in each disease and many different symptoms may be present. However, two main groups of manifestations can be recognized, depending on the nature of the enzyme deficiency: Photosensitivity is often a feature of those porphyrias in which there are excessive amounts of uro-, copro- or protoporphyrin in tissues. In practice, photosensitivity may be present in all

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