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Biomedical subjects

A Macchi

Publications and source records attributed to A Macchi.

At least 19 recordsLinked to original sources
PubMed1989

Angiotensin converting enzyme inhibition and renin release from the kidney.

Experiments were performed in anaesthetized cats, to determine whether renal nerves interfere with the negative feedback action of angiotensin II (Ang II) on renin release. The increase in renin release from the innervated kidney in response to captopril-induced inhibition of Ang II generation was compared with the response of the contralateral denervated kidney. Renin release was measured before (control), and 5, 15 and 30 min after the beginning of captopril infusion (1 mg/kg priming dose followed by 1 mg/kg per h for 30 min intravenously), and 60 min after the end of the infusion. During the captopril treatment renin release from both kidneys increased, but after 15 and 30 min the increase in renin release from the innervated kidneys was significantly larger than that observed in the denervated kidneys. After the captopril infusion was stopped, renin release from both kidneys returned towards control values. These results could not be explained on the basis of the changes in renal haemodynamics, excretory functions and efferent renal nerve activity observed during the captopril infusion. The data suggest that the renal nerves influence the changes in renin release caused by captopril by increasing the sensitivity of juxtaglomerular cells to the negative feedback action of Ang II.

Angiotensin II↗
PubMed1986

Renal responses to atriopeptin II are not dependent on renal nerves.

The possibility that renal responses to atriopeptin II (AP II) may depend in part on an inhibition of renal sympathetic nerve effects on the kidney was investigated in seven anesthetized Wistar rats in which one of the kidneys was denervated 7-10 days before experimentation. Clearance studies were done before, during, and after infusion of AP II (0.07 nmol . min-1 iv). During AP II infusion mean arterial pressure (MAP) decreased from 123 +/- 2 to 75 +/- 2 mmHg. Renal blood flow (RBF) was decreased significantly and renal vascular resistance was increased significantly in the innervated kidneys but not in the denervated kidneys during AP II infusion. Glomerular filtration rate during AP II infusion was not significantly altered, but urine flow rate and the excretion of sodium and potassium were significantly increased proportionately in both the innervated and denervated kidneys. These results suggest that 1) the decreased RBF observed in the innervated kidneys was due to an increase in renal vasoconstrictor nerve activity reflexly induced by the decrease in MAP during AP II infusion and 2) renal innervation was not necessary for AP II to produce a natriuresis and diuresis.

Animals↗
PubMed1984

Regulation of sodium and water excretions by neural renorenal reflexes in the cat.

The reduction in sodium and water excretion observed in the right kidney when the left kidney is subjected to transient denervation, is entirely abolished by bilateral section of the dorsal roots from T9 to L4, whereas section of the left dorsal roots only, at the same spinal level, does not affect the contralateral renal response to left renal nerve cooling. The possibility that the bilateral dorsal roots section abolished the response of the right kidney because the afferent fibres from the left kidney travel in the right dorsal roots was explored in the present study. Experiments were performed in anaesthetized cats in which reversible denervation of the left kidney was done by cooling of left renal nerves (for 10 min) after cutting the right dorsal roots from T9 to L4. Cooling of left renal nerves caused a large increase in sodium and water excretion from the left kidney and a prompt decrease in sodium and water excretion from the right kidney. During the cooling period arterial pressure did not change and glomerular filtration rate slightly increased in the left kidney only. The results obtained in this group of animals were not significantly different from those previously observed in sham-operated cats or in cats with section of left dorsal roots only. As the contralateral antidiuretic and antinatriuretic response to renal denervation survives dorsal root section on either side but is prevented by bilateral section, this demonstrates that the inhibitory renal afferent fibres responsible for this renorenal reflex are distributed bilaterally to spinal dorsal roots.

Animals↗
PubMed1980

Chemoimmunotherapy with Corynebacterium parvum in acute myelocytic leukemia.

The purpose of this study is to see if immunotherapy with C. parvum and prevention of central nervous system relapse with intrathecal methotrexate can prolong duration of complete remission and survival as well as avoid central nervous system relapse. For induction, three weekly I.V. injections of vincristine and Daunorubicin were given with daily prednisone orally, followed by 5-day courses of Cytosine Arabinoside and 6-mercaptopurine. The patients were randomized to chemotherapy or chemoimmunotherapy. Maintenance consisted of vincristine, Daunorubicin, and prednisone one week every odd month, and a 5-day course of Cytosine Arabinoside and 6-mercaptopurine every even month. Every week, the chemoimmunotherapy group also received, without chemotherapy, one injection of C. parvum 4 mg, subcutaneously. All patients received five weekly injections of intrathecal methotrexate 13 mg/m2 right after complete remission was achieved. Out of 181 evaluable cases, 80 (44%) achieved complete remission, 45 were randomized to chemotherapy, and 35 to chemoimmunotherapy. In the chemoimmunotherapy group 32/35 relapsed, and in the chemotherapy group 36/45. Median duration of complete remission and survival were: for group chemotherapy, 8 and 15 months; for group chemoimmunotherapy, 5 and 10 months. This difference is not significant. Intrathecal methotrexate was given to all patients. Six patients (7%) had central nervous system leukemia at the time of the first injection. None had central nervous system relapse after prevention with intrathecal methotrexate. This method seems useful in preventing central nervous system relapse in patients with acute myeloblastic leukemia, but does not seem to prolong complete remission.

Adolescent↗
PubMedDate not supplied

[Interceptive therapy of Class III].

The early morphofunctional reequilibration of skeletal III Class pattern is one of the keys of resolution of this complex and dramatic pathology. Long-term controls suggest the use of Quad-Helix and III Class elastic traction as soon as possible, in order to correct premaxillary and maxillary hypoplasia eventually complicated by a posterior cross-bite. The simplicity of interceptive therapy is inversally proportional to the benefits that could be obtained and which are reliable and stable.

Cephalometry↗
PubMedDate not supplied

[Set-up: method review and implementation of a new protocol].

At present the set-up occupies an important role in orthodontic therapy and is a valid help both at diagnostic and therapeutic level. The intent of this work is to illustrate the set-up execution technique in its principal passages, giving some useful indications to realize the correct dental displacements. For this reason it's necessary to insert some contrivances, which allow to control dental displacements into the three space dimenions. In this way it's possible to obtain an exact and valid set-up which can be destinated to many employments in orthodontic therapy.

Humans↗
PubMedDate not supplied

[Post-orthodontic retention: experimentation with a new technic].

Retention is a problem which has acquired a growing importance in orthodontic therapy. Some studies infact have proved that relapse cases may happen frequently at the end of an orthodontic treatment. To prevent these relapses it's necessary a suitable period of retention. In this work we took into consideration the problem of lower incisors crowding and we proposed a method of retention with the application of a fixed maintainer from cuspid to cuspid. This maintainer is applicated with some contrivances to reduce the risk of maintainer removal.

Humans↗
PubMedDate not supplied

[Lingual appliances].

We have considered all the tongue brackets in trade, and we have analyzed their quality and their defects on the grounds of our clinic experience. Tongue brackets must have small gingival occlusion dimension and fine thickness, while its breath must be compatible with rotation control. Finally we can say that there are no really effective tongue brackets in trade.

Humans↗