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Biomedical subjects

J W Ryan

Publications and source records attributed to J W Ryan.

At least 199 records · Page 11Linked to original sources
PubMed1968

A rapid simple method for the assay of renin in rabbit plasma.

1. EDTA (10mm), 2,3-dimercaptopropan-1-ol (10mm) and chlorhexidine gluconate (0.005%, w/v) cause complete inactivation of plasma enzymes that degrade angiotensin I, but have no effect on the reaction of renin with its substrate. The reagents were termed the selective inhibitors. 2. Thus it is possible to measure renin in plasma by its ability to catalyse the release of angiotensin I. 3. Sterile plasma, treated with the selective inhibitors, is incubated with renin substrate (500-1000ng. of angiotensin content/ml.) at pH6 at 42 degrees for 6hr. 4. Under these conditions the reaction obeys first-order kinetics. Renin activity is calculated in terms of the percentage release of the angiotensin content/hr. 5. As described, the assay is sufficiently sensitive to measure renin in the plasma of all normal rabbits. By extending the length of the incubation, much lower activities can be measured.

Alcohols↗
PubMed1968

Properties of renin substrate in rabbit plasma with a note on its assay.

1. Rabbit plasma enzymes that degrade angiotensin I are inhibited completely by the combination of 2,3-dimercaptopropan-1-ol (10mm), EDTA (10mm) and chlorhexidine gluconate (0.005%, w/v). These compounds do not modify the reaction of renin with renin substrate and are termed the selective inhibitors. 2. The renin substrate concentration of plasma can be measured as angiotensin I content by incubating plasma plus the selective inhibitors with renin for a time sufficient to allow complete utilization of renin substrate. 3. This reaction obeys first-order kinetics to substrate concentrations of at least 1000ng. of angiotensin I content/ml. In general, the renin substrate concentrations of normal rabbit plasmas are less than 1000ng. of angiotensin I content/ml. Thus the time required for the complete release of angiotensin I from normal plasma is inversely related to renin activity and is independent of renin substrate concentration. 4. A method for the assay of renin substrate, taking these reaction kinetics into account, is presented.

Alcohols↗
PubMed1967

Renin-like enzyme in the adrenal gland.

The rabbit adrenal gland contains an enzyme which reacts with renin substrate to form a vasopressor polypeptide, probably angiotensin I. In view of the strong effects of angiotensin on secretion of aldosterone and catecholamine, this finding suggests that there may be an intra-adrenal mechanism for the control of adrenal secretions.

Adrenal Glands↗
PubMedDate not supplied

Free gastroomental flap for head and neck reconstruction: assessment in an animal model.

This study was performed to evaluate the free gastroomental flap for the reconstruction of mucosal and soft tissue defects after ablative surgery for head and neck cancer. Its use in a dog model was assessed in terms of the feasability of the surgical technique, acid secretion by the gastric mucosa, changes in the cell population of the graft, and the possibility that the omentum may augment lymphatic drainage after cervical node dissection. Gastroomental flaps were harvested, based on the gastroepiploic artery, and transplanted to the neck in ten dogs. Neck dissection and creation of a defect in the floor of the mouth were followed by microvascular anastamosis of the gastroepiploic vessels to suitable recipient vessels in the neck. Following this, the flap was sutured into place, reconstructing the defect in the floor of the mouth. The omentum was draped over the carotid artery and into the upper mediastinum. Intraoral pH remained stable during a 6-month follow-up period and there was no stomatitis noted. Radionuclide images suggested that the omental lymphatics contributed to regional lymphatic drainage. Histologic examination following sacrifice at 6 months showed atrophy of gastric glands but no epithelial metaplasia. We conclude that the free gastroomental flap is feasible, provides immediate restoration of soft tissue bulk, supplies a mucosal surface that adapts to the oral environment, and may augment regional lymphatic drainage.

Animals↗