, Juraj Payer2 and Manfred Herold3
(1)
National Institute for Rheumatic Diseases, Piestany, Slovakia
(2)
Fifth Department of Internal Medicine, Comenius University University Hospital, Bratislava, Slovakia
(3)
Department of Internal Medicine VI, Medical University of Innsbruck, Innsbruck, Austria
Nailfold capillaroscopy An examination using widefield microscopy of the nailfold capillary bed 10–200-point zoom. It has been useful in diagnosing and observing the progress of systemic connective tissue diseases, especially systemic sclerosis. Changes in capillaries can also be detected in diabetes mellitus, arterial hypertension, atherosclerosis and other disorders. The simplicity, non-invasiveness and affordability are all advantageous.
The capillaries of the finger nailfolds on the hands are the most appropriate for monitoring microvasculature in vivo as they run parallel to the surface of the skin. The skin transparency can be increased by local application of an immersion oil. A capillaroscope or videocapillaroscope capable of scanning and recording the capillaroscopic picture by a camera can be used to record the picture. Alternatively, a stereomicroscope, a modified standard microscope or an ophthalmoscope can be used.
A microvasculature, including arterioles, precapillaries, capillaries and venules, is all viewed by nailfold capillaroscopy. The shape of the capillaries is evaluated in the morphology assessment. The capillaries may be dilated, coiled and branched or have the shape of a bush. Dilatation of the capillaries may be graded in a qualitative or quantitative way. Concurrent elongation and dilatation of the capillaries is referred to as capillary enlargement.
Subpapillary venous plexus | A reticular plexus visible proximally from the edge of the nailfold. Microhaemorrhage – Leaking of erythrocytes from capillaries, often visible with the naked eye, growing out of the nailfold. |
Avascular regions | Areas lacking capillaries on the distal edge of the nailfold. Their size is expressed in mm2. |
Decreased number of capillaries | This is evaluated by counting the number of capillaries per 1 mm at the edge of the nailfold and/or per l mm2 from its proximal edge. The capillary count varies between 9 and 13 per 1 mm. |
Variability of the capillaroscopic picture and morphology changes to capillaries can also occur in healthy individuals, but are usually mild in degree, and between different fingers. They are often due to microtrauma (manual work, influence of chemical agents, etc.). A normal capillaroscopic finding is found in approximately 80 %. In healthy individuals, the microvasculature in the nailfold does not change greatly over long-term observation. Nailfold capillaroscopy can assess functional disturbances in microcirculation in vivo using a higher magnification, thus monitoring the flow of erythrocyte aggregates and plasma gaps in the arterial and venous arm of the capillary loop. The examination should be performed under resting conditions, because the flow velocity varies with temperature and mental status, even during the examination.
Naive lymphocytes Lymphocytes which have not met a specific antigen and therefore did not have the opportunity to be activated by the antigen and subsequently be differentiated into memory and efficient cells. All lymphocytes that leave the pivotal (central) lymphoid organs are naïve. Those leaving bone marrow are naive B lymphocytes, and those leaving the thymus are naive T lymphocytes.
Necrosis The local death of cells or tissues due to chemical or physical damage or after complete interruption of blood supply to the affected tissue. It differs from apoptosis (biologically programmed death of cell). After necrosis, an inflammatory response develops, not after apoptosis. Migration of the inflammatory response to the area of necrosis is mediated by necrotaxis.
Necrosis of tibial tuberosity of the femur in children – see Osgood–Schlatter disease.
Negative thermal therapy Local cryotherapy is used in inflammatory rheumatic diseases in order to suppress inflammatory symptoms, provide pain relief and muscle relaxation and reduce swelling. Systemic application of coldness is used in cases of hyperpyrexia and in cryochambers for the purpose of managing inflammation, e.g. in rheumatoid arthritis. Cryotherapy has similar effects to thermal therapy (pain relief, muscle relaxation).
Neonatal lupus A syndrome of dermal lupus and inherited complete heart block in the newborn of some mothers with SLE, Sjögren’s syndrome or other connective tissue inflammatory diseases caused by the transplacental passage of maternal IgG antibodies against anti-Ro (SSA). Anti-La (SSB) antibodies and rarely also anti-U1RNP may also be present. Anti-Ro (SSA) antibodies are not only an important marker but play a significant role in the pathogenesis of the disease. Using an indirect immunofluorescent technique, deposits of immunoglobulins can be found in the conduction system of the heart in the week 9–10 of pregnancy. Apart from the above-mentioned clinical symptoms, inherited heart defects, cardiomyopathies and myocarditis may also be present as part of neonatal lupus. Other symptoms include haematological disorders (haemolytic anaemia, leucopenia and thrombocytopenia), hepatosplenomegaly and occasionally pulmonary and neurological symptoms. Clinical symptoms, except for complete heart block, usually disappear within 1 year of birth with the disappearance of the antibodies.
Neopterin A metabolite of guanosine triphosphate (GTP) produced by macrophages after IFN-γ stimulation. The level of neopterin in serum and urine of HIV-1-infected individuals increases in proportion to the progression of AIDS. An increased level of neopterin along with a decreased number of T-helper-lymphocytes (CD4+) is amongst the major indicators of the initial conversion from the asymptomatic phase of HIV-1 infection to the clinical symptoms of AIDS.
Nerve A bundle of nerve fibres (axons) forming part of the peripheral nervous system. The majority of nerves consist of motor and sensory fibres (mixed nerve). Certain cranial nerves contain only sensory fibres and serve for specific purposes like smell, vision, hearing and vestibular function.
Nervous system A complicated system of nerve cells whose primary function is to monitor, protect and respond to changes in the internal and external environment. The system is divided into the central nervous system (CNS; brain and spinal cord), peripheral nervous system (PNS; cranial and spinal nerves) and autonomous nervous system (ANS), which is a subdivision of spinal motor nerves. The ANS is subdivided into the sympathetic system (prepares the organism for extreme situations) and the parasympathetic system (restores and preserves physical energy during rest periods).
Neuralgia Pain localised in the area supplied by one or more nerves.
Neurogenic arthropathy The disease does not belong to the group of post-traumatic athropathies, although it is sometimes seen as a trauma to the arthritic joint, since the joint is instable, with the radiologic scan showing visible broken-off pieces of the bone, ossification myositis and pathological fractures.
It is caused by incorrect function of the afferentation of proprioceptive receptor whilst keeping motor functions.
The most frequent cause of neurogenic arthropathy is syringomyelia; in case of knee involvement, it is tabes dorsalis and in case of foot diabetes mellitus.
Most often, the joint is painless; however, sometimes it can be very painful. In such case, the acute arthritis is most often caused by hydroxyapatite crystals or CPPD.
The joint is deformed by large osteophytes to a great extent, and it is usually instable.
Radiologic signs: The radiologic scan shows joint destruction, very bizarre osteophytes, per- and intra-articular ossification, chondrocalcinosis, loose joint objects and pathological fractures.
The disease is easily diagnosed based on the neurological disease and typical radiologic findings.
Therapy: NSA (non-steroid antirheumatic agents) are applied as necessary, with bed rest and orthosis prescribed in case of instability. Surgical solutions have no good results.
Neurogenic pain Pain caused by damage or intermittent impairment of the peripheral or central nervous system. The term is mainly used as a general name for peripheral or central nervous system lesions of various aetiologies. For more specific determination, the term peripheral and central neurogenic pain may be used.
Neuron The neuron is an electrically excitable cell forming the basic structural and functional unit (nerve cell) of the nervous system. It consists of a cell body, dendrites and axon. Functionally neurons can be divided into sensory, motor or combined neurons. From a structural point of view, the neuron can be pseudo-unipolar, bipolar and multipolar (most of them). The afferent neuron carries impulses from sensory receptors to the central nervous system. Efferent neurons carry impulses from the central nervous system to effector organs (muscles and glands).
Neuropathic arthropathy – see Charcot’s joint (neuropathic arthropathy).
Neuropathic pain Pain caused by damage to the peripheral or central nervous system. Pain due to peripheral nervous system lesions (neuropathy) is usually burning or an electric shock-like pain, due to firing of pain and non-pain sensory nerve fibres.
Neurotransmitters Chemicals localised in nerve axon terminals that are released into the synaptic gap where they induce excitatory or inhibitory postsynaptic potentials. Acetylcholine, dopamine, noradrenaline, glutaminic acid, serotonin, endorphin, encephalin, substance P and others belong to this group.
Neutrophils Belongs to granulocytes and also called neutrophil granulocytes or polymorphonuclear leukocytes (PMN). They are present in peripheral blood (45–70 % of circulating leukocytes) or are either tethered to the endothelium of blood vessels (so-called marginal pool) or deposited in tissues where they move particularly during inflammatory reactions (inflammation). They are typical professional phagocytes as they have immunoadherent receptors on their surface through which they are effectively able to perform the phagocytosis of particles (including pathogenic microorganisms) opsonised by antibodies or by iC3 fragment of complement. The enzyme NADPH oxidase, which initiates the production of oxygen dependent antimicrobial and cytotoxic substances (reactive oxygen intermediates [ROI]), is activated in their cytoplasmic membrane during contact of the neutrophils with the particle or by chemotactic factors. ROIs along with oxygen independent factors (defensin, lactoferrin, neutral proteinases) kill phagocytosed cells. Oxygen-independent antimicrobial substances are present in their progenitor forms in the granules (granule of leukocytes). Neutrophil granulocytes are paramount in defence against extracellular pathogenic parasites and are the first cells to appear in the area of inflammation. As with macrophages, neutrophils can also be present in the three stages quiescent (resting), pre-activated and activated. Activated neutrophils possess the most efficient antimicrobial and cytotoxic activity, which can also cause damage to their own tissues.
Neutrophilic dermatoses A group of noninfective diseases characterised by skin lesions which on histopathological examination show intense inflammatory infiltrates of mainly neutrophils. The term neutrophilic dermatosis is sometimes associated with a good response of these diseases to glucocorticoids and immunosuppressive agents.
Nitric oxide (NO) A mediator of immune, nervous and the cardiovascular system. NO is a product of NO synthase activity and a free radical containing one disparate electron.
NO synthase (nitric oxide synthase, NOS) Synthase of NO, an enzyme that removes NO in the form of a free radical (NO.) from the guanidine group of L-arginine, leading to L-citrulline production. Subsequently other reactive products derived from nitrogen (reactive nitrogen intermediates [RNI]) develop. In the human body, the enzyme is present in three isoforms: constitutive neurogenic NO synthase (nNOS), constitutive endothelial synthase (eNOS) and inductible synthase (iNOS). nNOS is present in neurons and skeletal muscles, eNOS in endothelial cells and iNOS mostly in macrophages, but also in a number of cells of epithelial, myeloid or mesenchymal origin. NO has a number of physiological functions (involvement in defensive inflammation, immune responses, cardiovascular and nervous system regulations) and pathological functions (harming inflammation, direct toxic damage of tissues). In immune responses, it acts as a regulator and an effector (harming) molecule. NO synthesised by eNOS is involved in the regulation of blood pressure, causing relaxation of smooth muscles of vessels, whereas in the nervous system NO plays the role of neurotransmitter of nitrergic (non-adrenergic and non-cholinergic) neurons.
Nociception All processes due to nociceptor activation. Nociception does not always lead to painful sensation and vice versa. The pain does not always have to be caused by nociception (pain without nociception like psychogenic pain).
Nociceptive pain – see Types of pain.
Noninflammatory myopathies A group of muscular diseases in which muscle fibres are subject to damage and necrosis. Electromyographic examination confirms myogenic lesion. Serum muscle enzymes become raised during degradation of a large number of muscle fibres. Biopsy of muscle confirms muscle fibre atrophy which is non-neurogenic in origin and the necrosis of muscle cells without inflammatory changes. Some myopathies are hereditary, whereas the remainder are of toxic origin (drugs).
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