Revisión histórica de la fisiología de las glándulas paratiroides / Historical review of the physiology of parathyroid glands

Las glándulas paratiroides fueron identificadas por primera vez en humanos, por Ivan Sãndstrom (1880). Von Recklinghausen en 1891 describe un "linfonódulo marrón rojizo" bajo la tiroides de un paciente con fibrosis quística ósea. Ese mismo año Gley asocio la pérdida en la función de las paratiroides con la tetania. Vassale y Generali publicaron un trabajo en 1897 realizado tras tiroidectomías en perros y concluyen que una de las funciones de las paratiroides era la remoción de toxinas, concordando con la "teoría de detoxificación". G. Moussu (1898) clamó haber tratado satisfactoriamente a un paciente con tetania administrándole extracto acuoso de paratiroides equinas. En 1903 Askanazy establece que los tumores de la glándula tiroides u otras glándulas endocrinas y afecciones descalcificantes esqueléticas podrían relacionarse al describir el primer caso de asociación entre un tumor paratiroideo y la enfermedad de Von Recklinghausen. MacCallum y Voegtlin (1924), tras numerosos estudios, dedujeron que la paratiroides actuaba como moduladora del metabolismo del calcio. Collip (1925) confirmó el rol protagónico de las paratiroides en la regulación del calcio mediante experimentos basados en que la "paratirina" podía aliviar la tetania post-paratiroidectomía Barnicot en 1948 concluye que la hormona paratiroidea estimula la resorción osteoclásica de forma directa; ese nismo año, Jahan y Pitts demostraron que esta hormona incrementa la reabsorción renal tubular de calcio y magnesio. En 1973, Aurbach purifica cierta cantidad de hormona paratiroidea, caracterizándose su estructura proteica y molecular. La clonación de su receptor por Jüppner y Abou-Samra (1991) permitió estudiar con mayor énfasis sus acciones celulares.

Parathyroid glands were identified by the first time in human beings by Ivan Sãndstrom (1880). Von Recklinghausen in 1891 describes "lymph node reddish brown" low thyroid of patients with fibrosis cystic in bones. The same year Gley associated the loss in the function of the parathyroids with tetania. Vassale and Generali published a review in 1897 realized after thyroidectomies in dogs and they concluded that one of the parathyroid functions was the renoval of toxins, agreeing with "theory of detoxification". G. Moussu (1898) cried out to have treated satisfactorily a patient with tetania administering watery extract of equine parathyroids. In 1903 Askanazy establishes that the tumors of the thyroid gland or other endocrines glands and decalcifying affections of the skeleton might be related on having described the first case of association between a parathyroid tumor and Von Recklinghausen's disease. Mac callum and Voegtlin (1924), alter numerous studies, deduced that parathyroid was actuating like modulating of the metabolism of the calcium. Collip (1925) confirmed the leading role of the parathyroid glands in the regulation of calcium by means of experiments based on which the "parathyrina" could relieve the postparathyroidectomy tetania. Barnicot in 1948 concludes that the parathyroid hormone stimulates the osteoclastic resorption directly, the same year, Jahan and Pitts demonstrated that this hormone increases the renal tubular reabsorption of calcium and magnesium. In 1973, Aurbach purifies certain quatity of parathyroid hormone, its multifaceted and molecular structure being characterized. The cloning of its receptor for Jüppner and Abou-Samra(1991) allowed to study with bigger emphasis its cellular actions.

Post-tetanic count [PTC]: a new technique of evaluating profound neuromuscular block of different non-depolarizing muscle relaxants

Forty five adult patients scheduled for eye or ear surgery were studied to evaluate the PTC as a method to predict neuromuscular recovery. They were given either 0.08 mg kg[-1] pancronium, 0.1 mg kg[-1] vecuronium or 0.5 mg kg[-1] atracurium during thiopental-nitrous oxide-halothane anaesthesia. Ulnar nerve at the wrist was stimulated and the force of contraction of the adductor pollicis was recorded, we focused on the period of intense neuromuscular block [the period of no response] using the PTC method. This study showed that PTC method can give early warning about the onset of neuromuscular recovery offering the opportunity to give supplementary doses of muscle relaxant at the proper time. The first response to post tetanic twitch stimulations appeared on average 35.5, 9 and 11 min. before the first detectable response to TOF stimulation for patients given pancuronium. vecuronium and atracurium respectively. This study proved a close relationship between PTC and time interval between the PTC and the first detectable response to TOF nerve stimulation. We concluded that PTC method can effectively monitor part of the period of no response and can be used to predict the time to appearance of the first detectable response to TOF. It is a valuable supplement to TOF stimulation during clinical anaesthesia

Fatigue and contractile responses of rat hindlimb muscles following excessive dexamethasone administration.

Muscle weight, protein content and contractile performance (tetanic tension, fatigue and recovery) of extensor digitorum longus and soleus were investigated in rat following systemic administration of Dexamethasone (DX), 5 mg/kg/day for ten days. These animals showed marked reduction in food intake during the course of DX treatment. As a control, a group of food restricted (FR) rats receiving equal amount of food consumed by the DX treated rats was also studied along with the saline control group, to differentiate the effect of DX on muscle from that of dietary deficiency. There was a greater degree of atrophy (reduced muscle mass and protein content) of extensor digitorum longus in DX treated rats as compared to that of the FR rats. In-situ isometric tetanic tension per gram of muscle and per unit weight of protein was similar in both the muscles in the DX treated and the FR rats. There was increased fatiguability with reduced post fatigue recovery in both the muscles of DX treated rats as compared to the FR rats. The results indicate that besides atrophy of fast twitch muscles, DX increases the fatiguability and decreases the postfatigue recovery in both fast and slow muscles.