Có 20+ tài liệu thuộc chủ đề "harrison intenal medicine"
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is associated with decreased activity of the enzyme uroporphyrinogen decarboxylase associated with a number of gene mutations. In both types of PCT, the predominant feature is a chronic photosensitivity characterized by increased fragility of sun-exposed skin, particularly areas subject to repeated trauma such as the dorsa of the hands, the forearms, the face, and the ears. moist erosions, often with...
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Photosensitivity and Other Reactions to Light. Natural photoprotection is provided by structural proteins in the epidermis, particularly keratins and melanin. Other forms of photoprotection include clothing and sunscreens. Sunscreens are now considered to be over-the-counter drugs and category I ingredients are recognized by the U.S. Food and Drug Administration (FDA) as monographed and safe and effective. These are listed in...
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Vitamin D metabolites from the circulation or those produced in the skin itself can augment epidermal differentiation signaling. human skin to photocatalytically produce vitamin D 3 , the widespread use of sunscreens that filter out UV-B has led to concern that vitamin D deficiency may become a significant clinical problem in the elderly.. Higher but irregular melanosome content may be...
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Underlying Systemic Diseases that Cause or Exacerbate a Bleeding Tendency. The clinical evaluation of a patient with a bleeding tendency must therefore include a thorough assessment for evidence of underlying disease. Bruising or mucosal bleeding may be the presenting complaint in liver disease, severe renal impairment, hypothyroidism, paraproteinemias or amyloidosis, and conditions causing bone marrow failure. All coagulation factors are...
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Bleeding and Thrombosis (Part 7). The most important point in a history related to venous thrombosis is whether the thrombotic event was idiopathic (meaning there was no clear precipitating factor) or was a precipitated event. In patients without underlying malignancy, having an idiopathic event is the strongest predictor of recurrence of venous thromboembolism. In patients who have a vague history...
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The most commonly used screening tests are the PT, aPTT, and platelet count. The PT assesses the factors I (fibrinogen), II (prothrombin), V, VII and X (Fig. The PT measures the time for clot formation of the citrated plasma after recalcification and addition of thromboplastin, a mixture of TF and phospholipids. The sensitivity of the assay varies by the source...
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Individual factor assays are usually performed as modifications of the mixing study, where the patient's plasma is mixed with plasma deficient in the factor being studied. The thrombin time, but not the reptilase time, is prolonged in the presence of heparin.. Heparin in the patient sample inhibits the enzymatic conversion of an Xa-specific chromogenic substrate to colored product by factor...
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Enlargement of Lymph Nodes and Spleen. Enlargement of Lymph Nodes and Spleen: Introduction. This chapter is intended to serve as a guide to the evaluation of patients who present with enlargement of the lymph nodes (lymphadenopathy) or the spleen (splenomegaly). Lymphadenopathy is a rather common clinical finding in primary care settings, whereas palpable splenomegaly is less so.. Lymphadenopathy may be...
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Enlargement of Lymph Nodes and Spleen. Laboratory Investigation. The laboratory investigation of patients with lymphadenopathy must be tailored to elucidate the etiology suspected from the patient's history and physical findings. One study from a family practice clinic evaluated 249 younger patients with "enlarged lymph nodes, not infected". No laboratory studies were obtained in 51%. When studies were performed, the most...
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Structure and Function of the Spleen. The spleen is a reticuloendothelial organ that has its embryologic origin in the dorsal mesogastrium at about 5 weeks' gestation. It arises in a series of hillocks, migrates to its normal adult location in the left upper quadrant (LUQ), and is attached to the stomach via the gastrolienal ligament and to the kidney via...
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The most common symptoms produced by diseases involving the spleen are pain and a heavy sensation in the LUQ. Pain may result from acute swelling of the spleen with stretching of the capsule, infarction, or inflammation of the capsule. However, Soma Weiss, in his classic 1942 report of the self-observations by a Harvard medical student on the clinical course of...
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The differential diagnostic possibilities are much fewer when the spleen is. palpable more than 8 cm below the left costal margin or its drained weight is ≥1000 g (Table 60-3). The vast majority of such patients will have non-Hodgkin's lymphoma, chronic lymphocytic leukemia, hairy cell leukemia, chronic myelogenous leukemia, myelofibrosis with myeloid metaplasia, or polycythemia vera.. Table 60-3 Diseases Associated...
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Many of the diseases associated with splenomegaly are listed in Table 60-2.. Hyperplasia or hypertrophy related to a particular splenic function such as reticuloendothelial hyperplasia (work hypertrophy) in diseases such as hereditary spherocytosis or thalassemia syndromes that require removal of large numbers of defective red blood cells. immune hyperplasia in response to systemic infection (infectious mononucleosis, subacute bacterial endocarditis) or...
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Barkun AN et al: The bedside assessment of splenic enlargement. Graves SA et al: Does this patient have splenomegaly? JAMA . Kraus MD et al: The spleen as a diagnostic specimen: A review of ten years' experience at two tertiary care institutions. Pangalis GA et al: Clinical approach to lymphadenopathy. Barkun AN et al: Splenic enlargement and Traube's space: How...
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The various leukocytes are derived from a common stem cell in the bone marrow. In normal humans, neutrophils are produced only in the bone marrow. A decrease in the number of blood neutrophils is called neutropenia
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Figure 61-2. Figure 61-3. The neutrophil with a sausage-shaped nucleus in the center of the field is a band form. Döhle bodies are discrete, blue-staining nongranular areas found in the periphery of the cytoplasm of the neutrophil in infections and other toxic states.. Figure 61-4. Normal granulocyte.. The normal granulocyte has a segmented nucleus with heavy, clumped chromatin. fine neutrophilic...
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Disorders of Granulocytes and Monocytes. In this benign disorder, the majority of granulocytes. The nucleus frequently has a spectacle-like, or "pince-nez,". In severe acute bacterial infection, prominent neutrophil cytoplasmic granules, called toxic granulations, are occasionally seen. 61-3), can be seen during infection and are fragments of ribosome-rich endoplasmic reticulum. Large neutrophil vacuoles are often present in acute bacterial infection and...
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Neutrophil travel through the pulmonary capillaries is dependent on neutrophil deformability. Neutrophil rigidity (e.g., caused by C5a) enhances pulmonary trapping and response to pulmonary pathogens in a way that is not so dependent on cell-surface receptors. Intraalveolar chemotactic factors, such as. those caused by certain bacteria (e.g., Streptococcus pneumoniae) lead to diapedesis of neutrophils from the pulmonary capillaries into the...
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A defect in the neutrophil life cycle can lead to dysfunction and compromised host defenses. Inflammation is often depressed, and the clinical result is often recurrent with severe bacterial and fungal infections. Patients with congenital phagocyte defects can have infections within the first few days of life. Skin, ear, upper and lower respiratory tract, and bone infections are common. In...
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Congenital forms of neutropenia include Kostmann's syndrome (neutrophil count <100/µL), which is often fatal due to mutations in the anti-apoptosis gene HAX-1. the cartilage-hair hypoplasia syndrome due to mutations in the mitochondrial RNA-processing endoribonuclease RMRP. Shwachman-Diamond syndrome associated with pancreatic insufficiency due to mutations in the Shwachman-Bodian-Diamond syndrome gene SBDS. neutrophil hypersegmentation and bone marrow myeloid arrest due to mutations...