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Q 174X) generic 100 mg dapsone amex,12 adults typically have high hypermetropia o f + 10 t o +18 Bangladeshi (p cheapest dapsone. Ш5 generic dapsone 100 mg overnight delivery,,7л*’2‘>The finding of m ul In addition to being flat, the cornea can exhibit variable tiple founder mutations in the Saudi Arabian patients (as deep stromal opacities that are typically central or opposed to the Finnish patients) can be explained by the paracentral. As is typical, he has accommodative esotropia associated with his uncorrected high hyperopia (+ 10 diopters in both eyes). In addition to correcting the esotropia and improving vision, wear of the full hyperopic correction provides some cosmetic improvement as the corneas are magnified. Abnormalities of the iris can occur, including hypoplasia, Prior reports suggest the horizontal corneal diameter to be syncchiac, and/or corectopia. He had had a trabeculectomy with mitomycin-C depth, some showed that patients had shorter-than-average for narrow-angle glaucoma at 11 years of age before he was depth,1119 while others found depths that were within first referred to me. The m ost typical features of autosomal recessive cornea plana are demonstrated m this slit-iamp photograph: a Hypermetropia is typically not more than + 12 diopters, grossly flat small cornea with a broad. Common but more variable features of recessive cornea plana are shown in two different patients. On the right, early and prominent arcus iipoides is evident in an affected teenage girl. Vanable deep stromal opacity can occur in recessive cornea plana, as shown in three different patients. One study documented anterior Early arcus Iipoides has been described in some patients. Rarely, accjuired non-traumatic corneal decompensation (stromal haze and thickening without epithelial changes) can occur in recessive cornea plana, as shown in the left eye (right photograph) of a 45-year-old woman v«ho also has prominent arcus lipoides. Glaucoma is not documented in most reported patients; however, one woman from a Cuban family had documented ciosed-angle glaucoma. Microphthalmia may be simple (a small but other amino acid small leucine-rich proteoglycan/2 4 (Figure 6. In microcornea, corneal diameter is below normal (< 10 mm), with the rest of the eye being normal. Refraction can range from hyperinetropia to myopia depending upon axial length; inheritance can be sporadic, recessive, or dominant. This 9-year-old has clear can be unilateral or bilateral, can be associated with 9-mm corneas with normal keratometry, anterior chamber depths, and corneal flattening, and can occur with other ocular and/or axial lengths. Unlike cornea plana, microphthalmia is associated with a small globe (with or without other ocular another hydrophic amino acid, and N is asparagine). Sclerocornea refers to congenital opacification of most of the cornea, causing the cornea to resemble sclera. Leucine rich repeats (L x x L x L x x N x L x ) 0 Keratocan I C ysteine residue т N -glycosylation site I for Keratan sulfate 4 _________________________________________________________X Fi£unG. Rarely, congenital ing the fact that the phenotype for the disorder is specific for pupillary abnormalities may necessitate pupilloplasty. One is two with documented astigmatic progression15-1* and one the possibility of progressive corneal astigmatism (reported with corneal hydrops. Am J Ophthalmol for the existence of a dominant gene located in the region 1971;71:1254-8. Clinical and m olecular character m utation causing autosom al recessive cornca plana. Invest ization o f a patient with an interstitial deletion o f chrom osom e O phthalm ol Vis Sci 2001 ;42:3118-22 I2ql5-q23 and peripheral corneal abnorm alities. Evidence o f gcnetic characterization o f a family with autosom al rcccssivc cornca plana. I Pediatr O phthalm ol Strabismus m utation in a British family with cornca plana. J Biol nant cornca plana: clinical findings in a Cuban family and a review of Chcm 1999;274:18843-6. O phthalm ic G enet 2007;28: kcratan sulfate proteoglycan, is regulated by lumican. Traboulsi This chapter covers the clinical aspects of congenital malformations of the cornea, anterior chamber angle and some of those that involve the iris and lens. It reflects the anatomic proximity of the involved structures rather than common pathogenetic or cmbryopathic mechanisms among the different anomalies. This occurs over varied temporal and spatial domains in the development of the embryo. Epigenetic phenomena also play a part in the very variable phenotypes seen in specific gene disorders. The anterior segment is enlarged at the expense of the vitreous length—hence the synonym ante R&ute 7. This enlargement is best documented shagreen) in a patient with Х-linkcd megalocornea. Carrier females do with decreased endothelial cell density and characteristic not have any corneal anomalies. There is a well-recognized autosomal recessive bowing, pigment dispersion, secondary glaucoma, iridodo- syndrome of megalocornea and mental retardation nesis, lens dislocation and vitreoretinal abnormalities. These include partial trisomy 16q,16sporadic17and cataracts,3341subluxated lenses and glaucoma. Careful anterior segment microcornca involve more generalized ocular malformation examination supplemented with biometry is essential. Management of megalocornca consists of the exclusion Hypermetropic refractive error and associated amblyopia of congenital glaucoma and the recognition of associated may require treatment. Ocular size, as determined by ultrasonography, is resulting in corneal opacification. Microcornea may be inherited in a dom of associated ocular anomalies have been reported. Both of these arc in the context genetic heterogeneity with other pedigrees reported of severe ocular malformations. Ultrasound biomicroscopy is essential to delineate the anterior segment structure and plan surgery. Tlic dermoids straddled the limbus for 360 degrees in all patients and extended about n&oit! There is a wide variation in clinical expression within families where the disease is inherited as an autosomal dominant trait. Some infants are Definition, Morphology, and Histopathology discovered because of the abnormal appearance of the iris. In the Axenfeld-Rieger spectrum a variety ofanterior ocular Others have signs and symptoms of infantile glaucoma segment malformations arise from abnormal development such as tearing, photophobia, and corneal clouding. Terms that diagnosis in other patients is made in adolescence or early have been used to describe the various phenotypes of these adulthood, when they may present with visual loss and are anterior segment abnormalities include anterior chamber found to have advanced childhood or juvenile glaucoma. Non dysgenesis mesodcrmalis of the iris and the Axenfeld-Rieger ocular abnormalities suggesting a diagnosis of Rieger syndrome.
The examiner then places the ulnar aspect of the hands on the left and right posterior chest wall while the patient repeated the words toy boat to identify asymmetry in sound transmission with increased vibrations associated with consolidation and decreased vibrations associated with pneumothorax order dapsone paypal. Percussion of the left and right anterior and posterior chest is then performed to identify asymmetry of sound purchase dapsone now. Pneumothorax will result in a tympanic sound and areas of pleural effusion and consolidation will yield a more dampened sound generic dapsone 100mg otc. Auscultation is carried out with the stethoscope and the respiratory sounds are assessed by comparing the left and right lung fields. Abnormal sounds such as rales, rhonchi, wheezes, crackles, whistles, stridor, and friction rubs are identified. Transmitted voice sounds are then assessed via auscultation by having the patient whisper the words blue balloons while looking for increase or decrease in the volume of the words heard by the examiner through the stethoscope. The whispered words will be louder in areas of consolidation and tumor and softer in areas of pneumothorax. Evaluation of all pathologic conditions of the pleura and lungs, and to a lesser extend the subcutaneous tissues and muscles overlying the pleura, begin with the ability to identify the rib, pleura, and lung. The rib will be identified as a hyperechoic curvilinear line with an acoustic shadow beneath it. The three layers of intercostal muscle, the external, internal, and innermost, will be identified in the intercostal space between the adjacent ribs (Fig. Color Doppler will help identify beneath the adjacent intercostal artery and vein (Fig. This space between adjacent ribs provides an excellent acoustic window which allows easy identification of the intercostal space and the pleura beneath it. Adjacent ribs with the intercostal space in between have been described as having the appearance of a flying bat (Fig. Longitudinal ultrasound image demonstrating adjacent ribs, the intercostal muscles, and pleura with the lung beneath. Longitudinal ultrasound view demonstrating the external, internal, and innermost intercostal muscles and the pleura and lung beneath them. The clinician should then identify the pleura which appears as a bright hyperechoic line known as the bright sunset pleural line due to its resemblance to the bright line that appears on the horizon as the point at which the sun sinks below the horizon (Figs. In health the pleura and adjacent lung should be seen to slide back and forth on one another during normal respiration. A,B: the ultrasound appearance of adjacent ribs and intercostal space between has been described as having the appearance of a “flying bat. Longitudinal lung scan with low-frequency curvilinear ultrasound transducer: two adjacent ribs and the echogenic pleural line between and below them. Visualization of the flying bat sign is useful for detection of the pleural line, and should be the first step in lung evaluation. Once these sonographic anatomic landmarks are clearly identified, the clinician can then proceed with ultrasound evaluation for pathology of the pleura and underlying lung. Ultrasound evaluation for pneumothorax is carried out with the patient in the sitting or semisupine position based on patient comfort. Since almost 100% of clinically significant pneumothoraces will have an anterior and/or inferior component when the patient is placed in the semisupine position, a linear high-frequency ultrasound transducer is then placed in the longitudinal plane with the superior aspect of the ultrasound transducer rotated approximately 15 degrees laterally on the anterior chest wall and an ultrasound survey scan is obtained (Figs. Since nearly all clinically significant pneumothoraces have an anterior and/or inferior component when the patient is placed in the semisupine position, a linear high-frequency ultrasound transducer is placed in the longitudinal plane with the superior aspect of the ultrasound transducer rotated approximately 15 degrees laterally on the anterior chest wall. After the pleura is identified, the next step is to ascertain if the pleura and adjacent lung are sliding back and forth with respiration. The sliding of the bright line of the pleura and underlying lung is known as the sliding lung sign and if present, always precludes pneumothorax in the anatomic area being imaged (Fig. It is important to note that while the presence of a sliding lung sign excludes the diagnosis of pneumothorax in the area being imaged, the converse is not true. The absence of a sliding lung sign, while highly suggestive of the diagnosis of pneumothorax, is also observed in the absence of pneumothorax in some patients who are posttotal pneumonectomy or who are suffering from acute respiratory failure, apnea, pleural adhesions, massive atelectasis, severe pulmonary fibrosis, phrenic nerve palsy, rapid mechanical ventilation with small tidal volumes, and cardiopulmonary arrest. In this setting the clinician should next turn his or her attention to the lung just adjacent to the pleura and image this area of lung using M-mode ultrasound. If no pneumothorax is present, the pleura and the lung beneath it have been described as having the appearance of “waves on a sandy beach” (Figs. The waves on a sandy beach pattern is caused by the reflection of ultrasound waves by the bright white line of the pleura which lies between the waves created by the relatively motionless chest wall, the sand beneath the white line which is created by the evenly moving lung below. M-mode ultrasound will also aid in the identification of the lack of lung sliding by demonstrating the stratosphere sign as the lines look similar to the contrail vapor trails left by a jet flying at high altitude (Fig. A: Oblique scan of an intercostal space, showing the pleural line and some horizontal repetition artifacts called A-lines. B: M mode is useful to objectify the lung sliding by visualization of the seashore sign. The pleural line is between waves (the motionless thorax wall, above) and sand (the respiratory moving lung, below). However, between two ribs, strictly half a centimeter below in the adult, the pleural “bright sunset” line is located. The horizontal A-lines that arise from the pleural line have clinical implications. A flagrant difference in the pattern which appears on either side of the pleural line. A: M-mode ultrasound will demonstrate the stratosphere sign in the presence of pneumothorax due to the absence of the motion of lung sliding on pleura. Exclusively horizontal lines are displayed, indicating complete absence of dynamics at the level of, and below, the pleural line (arrowheads), a pattern called the stratosphere sign. A: If a pneumothorax is present, the lung just adjacent to the pleura will have the appearance of “ripples on a pond” due to the artifact produced by the perturbation of the ultrasound waves caused discontinuity of the parietal and visceral pleura as the visceral pleura which closely adheres to the lung pulls away from the parietal pleura, which is attached to the chest wall. The sonogram of the highest point of the thorax in supine position shows a sector of reverberation artifacts that resemble ripples on a pond. This point is known as the “lung point” and it is identified by moving the ultrasound transducer from the anterior point at which the ripples on the pond sign is identified until the lateral margin of the anterior pneumothorax is reached (Fig. The normal waves on a sandy beach sign may alternate with the abnormal ripples on a pond sign when the patient is asked to take a deep breath as the area of lung which has pulled away from the chest wall moves back and forth under the ultrasound transducer as the chest wall expands and contracts with respiration (Fig. The location of the lung point has an added advantage when placing a chest tube as the clinician can avoid placing the tube into an area of normal lung. Clinical experience has shown that the presence of a lung point only in anterior position is indicative of a small to moderate pneumothorax and the more lateral and posterior the lung point is identified, the larger and more clinically significant the pneumothorax. Obviously, if there is a complete pneumothorax, the lung point will not be identifiable. On the right (time–motion), a sudden change is visible at the precise location where the collapsed lung, subject to a slight increase in volume during inspiration, reaches the wall. The “sandy” pattern generated by lung sliding instantaneously replaces a pattern formed by horizontal lines (arrow).
Surgical scrubs (greens) buy cheap dapsone 100mg on line, shoes/clogs and disposable cap must be worn in the operating room order dapsone 100 mg mastercard. Open the outer pack consisting of a sterile pair of gloves discount dapsone 100 mg line, dropping the sterile inner gloves into the sterile field created by opening out the gown pack. Procedure the first scrub of the day should last 5 minutes and subsequent scrubs should last 3 minutes. Keep your hands above your elbows and do not touch any non-sterile objects/surfaces. Wet your forearms and hands, allowing the water to drain downwards from your hands to your elbows. Lather the detergent and perform a pre-scrub, washing from the hands to 2 cm above the elbow and then rinsing. Using the brush and nail file, brush and file under the fingernails for 30 seconds per hand. Scrub each of the four surfaces of each finger, the palm, the back as well as the heel of the hand for a further minute per hand. Wash from the hands to the elbows for 1 minute without retracing your steps and then rinse, allowing the water to run away from your hands to your elbow. Pick up the towel, ensuring that it does not make contact with either your body or any non-sterile surface, and step away from the gowning table. Continue to hold your hands above your elbows, and dry your hands and forearms from distal to proximal using opposite sides of the same towel for each hand and forearm. Hold the gown away from you at the neck and at chest level and allow it to unfold. Slip your arms into the sleeves of the gown and advance your fingertips as far as but not beyond the proximal border of the gown cuffs. Pick up the left glove with your sleeve-covered left hand and place it on the opposite sleeve gown with the palm of the glove facing down and the fingers pointing towards you. Taking the folded edge of the glove with the thumb and index finger of your sleeve-covered left hand (palm facing upwards), use your sleeve-covered right hand to stretch the glove over the sleeve-covered left hand by grasping on the outer edge of the glove fold. Pull any excess sleeve from inside the glove using your sleeve-covered right hand. Pick up the right glove under its fold with your gloved left hand and pull the glove over your right hand. Finally, take the paper belt tab found at the front of the gown and pass it to the scrub nurse/assistant. The assistant will take the paper tab and move behind you to pass the belt (but not the paper tab) back to you. Suturing a wound Introduction, explain the procedure, confirm indication and obtain informed consent. Prepare the following on a procedure trolley: Appropriate local anaesthetic 10-mL syringe and 25-gauge needle Dressing pack Betadine Appropriate suture material and needle Local anaesthetics and suturing Figure 11. Maximum safe dose varies with anaesthetic used and patient’s weight – lignocaine (Xylocaine) safe dose: 5 mg/kg lignocaine plus adrenaline: 7 mg/kg bupivacaine (Marcain): 3 mg/kg. Concentration in mg can be calculated by multiplying percentage concentration by 10 (e. Clean the wound with Betadine, starting at the centre and working outwards without retracing old ground. Infiltrate the wound with local anaesthetic using a 25-gauge needle, not exceeding the maximum safe amount. Hold the forceps between thumb and index finger and use it to manipulate (not to crush) the skin edges. Forceps may be toothed (used for skin and tough tissue) or non-toothed (used for bowel and blood vessels). Hold the needle holder with the thumb and index fingers inserted in the bows advanced no further than the distal phalanx. Insert the needle at right angles to the skin, advance the needle through one skin edge, pick the needle up using forceps (not hands), remount and advance the needle through the opposite skin edge. Either instrument or hand-tie the suture, forming a reef knot, ensuring that the skin edges are ‘approximated not strangulated’ (Figure 11. Hold the scissors in a similar manner to the needle holder and cut using the tips of the scissors. Use the index finger of the opposite hand to support the scissors underneath while cutting. Successive sutures should be equidistant at a distance of twice the wound depth (Figure 11. As a rule of thumb, the distance of insertion from the edge of the wound should correspond to the thickness of the tissue being sutured (×). Introduction, explain the procedure, confirm indication and obtain informed consent Preparation Position Place the patient in either a sitting or supine position (if the cervical spine has not been cleared) with their arm, on the side that the chest drain will be placed, behind the head. Identify the fifth intercostal space in the mid-axillary line and mark it Gather the following equipment: Trocar-mounted chest drain (20–36 French) 1% lignocaine plus syringe and 26-gauge needle Minor procedures tray Betadine 0 silk suture Underwater seal drainage system Procedure Aseptic technique should be observed. Prepare the chest drain insertion site with Betadine and drape the patient to create a sterile field. Infiltrate the skin and tissues down to the pleura with local anaesthetic (always drawing back on the syringe before injecting, to avoid injecting into blood vessels). Make a 2-cm transverse incision over the upper border of the sixth rib to avoid the neurovascular bundle. Bluntly dissect the subcutaneous tissue and puncture the parietal pleura using either the tip of a clamp or a gloved finger. Layers that must be breached (superficial to deep) = skin, subcutaneous tissue, intercostal muscles, parietal pleura to enter the pleural cavity. Clamp the proximal end of the thoracostomy to help guide the drain into position, and introduce the drain, aiming for the apex (pneumothorax) or base (haemothorax) of the lungs. Attach the end of the chest drain to an underwater seal system and observe for bubbling (Figure 11. Apply an airtight dressing and secure the tube to the patient’s chest with tape (Sleek). This is the recommended site for insertion of a chest drain and is a triangle created by Mid-axillary line/anterior border of latissimus dorsi Lateral border of pectoralis major Imaginary horizontal line from the nipple Apex of the axilla (Figure 11. Pain Bleeding (with or without haemothorax) Inadvertent puncture of lungs, heart, great vessels or abdominal organs Damage to surrounding structures – Neurovascular bubble under each rib, long thoracic nerve of Bell Damage to the intercostal vein, artery and nerve Infection Subcutaneous emphysema Blockage of tube Recurrence of pneumothorax Persistent pneumothorax Failure of lung to expand (may require bronchoscopy) Figure 11. Preparation Gather the following on the procedure trolley: Spinal needles (21 gauge and 23 gauge) Procedure pack (containing gallipot, gauze, sterile drapes) Antiseptic Betadine/chlorhexidine solution Sterile gloves and gown 2% lignocaine (local anaesthetic) Syringe Manometer Positioning the patient Help to place the patient in the lateral decubitus position with the spine parallel to and at the edge of the bed. Ask the patient to draw their knees up to their stomach and flex their head to their chest, thereby flexing the vertebral column and widening the intervertebral spaces. Procedure Locate the L3–L4 interspace which is found along the supracristal line (an imaginary line between the iliac crests) and mark the puncture site. Prepare (prep) the skin over the puncture site and overlying several intervertebral spaces with Betadine/chlorhexidine solution applied in a circular fashion from the centre to the periphery. Using 2% lignocaine with a 25-gauge needle, raise a wheal over the puncture site to anaesthetise the skin, and then use a 21-gauge needle to infiltrate into the interspinous ligament.
Endoplasmic reticulum instead of being closer to the nucleus reassembles around the periphery of the cell body buy cheap dapsone. The Nissl granules gradually disintegrate and are stained weakly with basic dyes; this is known as chromatolysis (Fig discount dapsone 100 mg mastercard. Regenerative Changes the soma tries to repair the axon by synthesizing new struc‑ tural proteins that fills up and distends the cisterns of the rough endoplasmic reticulum purchase 100 mg dapsone with mastercard. Chromatolysis is reversible, if the neuron survives and re‑establishes its contact with the appropriate target. The Schwann cells that had survived the degeneration multiply and form rows along the pathway previously taken by the disintegrated distal axon. Out of the many sprouting branches, one branch finds the way through the Schwann cells and finally reinner- vates the original target structure. The Schwann cells then lay down their bilayered mem‑ diate change depicting swelling of soma, swelling of nucleus, brane to form the myelin sheath around the newly which is eccentrically placed, swelling of axon distal to the section; formed axon. The number of Nissl granules axon; (D) Regenerative changes with reduction in soma swelling, slowly reappears. The cell appearance of few Nissl bodies, development of growth cone and loses excess fluid and regains its normal size. The nucleus initiation of myelination; (E) Normalization of the soma and axon with re-establishment of axon contact with the target muscle. Therefore, when a neurotransmitter is released follow‑ Condition of Soma ing regeneration, the response of the target tissue to If the axonal damage is close to the cell body, a lager part the neurotransmitter is increased. Therefore, damage to the cell body, site of injury and secretion of even though the axonal sprouting occurs, the oligodendro‑ neurotrophins. Besides, glial scars formed by astrocytes pose obstruction Severity of Injury in the pathway of the growth cone. If neuroma is formed, successful regeneration can When specific neurotrophins are administered to the never occur. If the neuroma involves sensory fibers, pain is felt at is enhanced and enmeshing of the branches does not the site when touched. Nerve fibers are highly excitable tissues, strictly follow all-or-none law, and they do not exhibit fatigability. Nerve fibers are classified based on their fiber diameter and conduction velocity. A fiber has maximum diameter (12–20 µm) and maximum conduction velocity (70–120 m/s). The degenerative changes in the distal segment following nerve injury are called Wallerian degeneration. The target organ (muscle) responds more to stimuli due to upregulation of receptors. In the examinations, ‘degenerative and regenerative changes following nerve injury’ may sometimes come as a Long Question. InViva, examiners may ask about the properties of nerve fibers, definition of refractory period, All-or-none law, types of classification of nerve fibers, Erlanger-Gasser classification of nerve fibers, types of nerve fibers, features of Wallerian degeneration, regenerative changes following nerve injury. Explain the physiological basis of etiology, features and treatment of myasthenia gravis and Lambert-Eaton syndrome. This is also called myoneural junction or motor end plate, through the neurons innervating skeletal muscle fibers are known which action potential from the neuron is transmitted to as motor neurons that have their cell bodies in anterior horn of the spinal cord or in the brainstem. At this junction, the neuronal membrane myelinated and are the largest-diameter axons in the body. The terminals are covered by Schwann cells, known as understood synaptic connection in the nervous sys- teloglia (glial cells at terminals). It is readily visible under the light microscope, has fiber is supplied by one motor neuron terminal. The a relatively simple mechanism and easily accessible motor neuron, including its axon and axon terminals and to experimentation. Therefore, it is an ideal site for the muscle fibers supplied by it are called a motor unit. This is the part of the sarcolemma that lies directly under the terminal button (Fig. The area of the end plate membrane increases many times as it is thrown into several folds called junctional folds. Note that acetyl- choline vesicles are clear vesicles that are clustered at active zones sodium moves in than potassium coming out resulting + in the terminal buttons opposite to junctional folds. AchR allows the passage of only cations because contains more acetylcholine receptors and increase surface area the anions are repelled by the fixed negative charges for generation of electrical activities. This is the gap between the terminal button and the mus- cle fiber, which is about 40–100 nm wide. The muscle fiber is covered by a layer of amorphous connective tissue called the basement membrane or the purpose of presynaptic mechanism is to release ace- basal lamina, consisting of collagen, glycoproteins and tylcholine into the synaptic cleft. This causes activation and opening of the voltage- basement membrane by the presynaptic terminal and gated calcium channels, which leads to calcium influx. Various membrane proteins present in the vesicu- lar membrane as well as in the neuronal membrane are involved in the fusion process. Quantal Release Depolarization of the terminal button causes synchronous releases of about 60–200 vesicles from different parts of the presynaptic membrane. With each action potential, the presynaptic terminal discharges about the same amount of neurotransmit- ter, collectively known as a “quantum of neurotrans- mitter” or “quantal content”, which is synonymous with “number of vesicles released”. The voltage-gated Na chan- mechanism for their storage, release and inactivation”. The action potential propagates along the sarcolemma the mechanism of presynaptic events. As the motor end-plate is present at the middle of a muscle fiber, action potential propagates the released Ach molecules diffuse across the synaptic in both directions. The membrane poten- region and get bound to AchR, is sufficient enough to tial of the end plate returns to the resting state. The major purpose of postsynaptic mechanism is to gener- All these events at the neuromuscular junction occur ate action potential in sarcolemma adjacent to end plate. The neuromuscular transmission is disrupted at different steps by drugs, chemicals, toxins and trauma. Therefore, stimulation of a motor nerve always pro- Botulinum Toxins duces action potential in each muscle fiber supplied by the bacterium Clostridium botulinum releases a toxin that it; i. Under normal circumstances, the amount of neurotransmitters released is enough to activate about 10 times the number of receptors Box 25. Due to this 10-fold safety factor, stimulation of a motor neuron never fails to excite an action potential in the muscle fibers of its motor Clinical Uses of Botulinum Toxin: the paralytic effect of botulinum unit.