Trachea development

Ohshiro T, Saigo K. Transcriptional regulation of breathless FGF receptor gene by binding of trachealess/damt heterodimers to three central midline elements in Drosophila developing trachea. Development 1997 124 3975-3986. 

New techniques have been developed for the direct measurement of mucociliary transport rates in the trachea. Yeates et al. used an external gamma camera to follow a bolus of labeled microspheres deposited in the large airways by aerosol inhalation they fitted a log-normal distri-... 

Rats exposed to 12,000ppm for 4 hours survived, but exposure for 8 hours was lethal to half the animals. Mice exposed to 32 50ppm for 460 minutes developed ataxia, prostration, and finally narcosis. Guinea pigs exposed to 400 ppm for 24 successive hours had slight changes in the mucosa of the nose and trachea. 

All tissues are retinoid targets, as all cell types have at least one form of nuclear retinoid receptor. In adults, the most significant targets include cornea, skin, epithelia of the lungs and trachea, and the immune system. RA regulates the synthesis of proteins essential for growth or differentiation. Excessive vitamin A can cause birth defects, and pregnant women are advised not to use the retinoid creams that have been developed for treatment of severe acne. 

Phagocytosis and the reduction of nitroblue tetrazolium to formazan was impaired by chromium(III) but not chromium(VI). These effects represent a decrease in the functional and metabolic activity of the macrophage (Johansson et al. 1986a, 1986b). Mice exposed to chromium trioxide mist at concentrations of 1.81 and 3.63 mg chromium(VI)/m3 intermittently for i2 months developed perforations in the nasal septum, hyperplastic and metaplastic changes in the larynx, trachea, and bronchus, and emphysema (Adachi 1987 Adachi et al. 1986). 

In intermediate-duration animal studies, golden Syrian hamsters exposed to camotite uranium ore dust (AMAD=1.5-2.1 pm) at a concentration of 19 mg U/m by inhalation for 16 months failed to shown signs of cancer development upon examination of selected tissues including lungs, trachea, liver, kidneys, spleen, heart, and any abnormal tissue. As compared to unexposed controls, the hamsters had significantly more necrotic liver foci and inflammatory lung responses (Cross et al. 1981b). 

A 26-year-old woman undergoing bronchoscopy received lidocaine jelly 2% to each nostril, lidocaine solution 2% sprayed on the throat, and 10 ml of lidocaine solution 2% into the trachea. She was also given intravenous diazepam 5 mg and pethidine 75 mg and intramuscular atropine 0.6 mg. She developed dyspnea and cyanosis after the procedure and despite 100% oxygen, her Sp02 was 85%. Her methemoglobin concentration was 14%. 

A 67-year-old man developed transient hemiparesis and facial nerve palsy before becoming unconscious and apneic 10 minutes after a right cervical plexus block (89). His trachea was intubated without the need for anesthetic drugs and he was ventilated. Hypotension was treated with intravenous ephedrine. He woke up, started breathing, and was extubated 75 minutes later. The authors postulated brainstem anesthesia following accidental injection of local anesthetic into a dural cuff as a cause of loss of consciousness. 

Pig. 64.—Photomicrograph of a transverse section of an old portion of California Privet root, showing completed secondary development. Note the prominent medullary rays (mr) cork (cfe) phellogen (,ph) secondary cortex (between ph and p ) protophloem (p )i secondary phloem ( ) cambium (c) secondary xylem tracheae (0 wood fibers (w/) and piotoxylem ( ). 

Chiarino et al. [43] described some potent and remarkably selective (3o-adrenoceptor agonists in a series of l-(3-substituted-5-isoxazolyi)-2-alkyl-aminoethanol derivatives in which the isoxazole ring replaces the catechol moiety in the (3-adrenergic compounds. From this series, the compound broxaterol (1) displayed a marked selectivity toward (32-receptors of the trachea and was selected for further development as a potential bronchodilatory agent. 

In their first experiment, the Baylor doctors cross-clamped the trachea of some New Zealand rabbits. In other words, they strangled them. If you can t breathe, you can t get oxygen into your blood and, thus, to the heart muscle. Within 12 minutes the rabbit will develop cardiac arrest or ventricular fibrillation and die. 

As a very crude model for air flow in the trachea, assume fully developed laminar pipe flow at a Reynolds number of KKK). The diameter is 2.0 cm. 

Aerobiologists at the U.S. Army Medical Research Institute of Infectious Diseases (Fort Detrick, MD) have developed a reproducible, head-only ricin aerosol exposure model for laboratory nonhuman primates (NHP) that yielded acute LCtso values for African green monkeys or rhesus monkeys corresponding to approximately 6-10 or 15 pg/kg, respectively (Wilhelmsen and Pitt, 1996). Exposure of NHP to aerosolized ricin (particle size 1-2 pm) caused a dose-dependent toxicity that is delayed from 8 to 24 h early anorexia and lethargy were frequently observed, followed by gastric distress, hypothermia, hypotension, acute respiratory distress, and death. Rhesus monkeys exposed to the equivalent of approximately 20-40 pg/kg ricin by aerosol died from acute respiratory distress about 36-48 h after exposure necropsy revealed fibrinopurulent pneumonia, acute inflammation of the trachea and airways, and massive pulmonary alveolar flooding (Wilhelmsen and Pitt, 1996). 

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