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Biomedical subjects

A M Shapiro

Publications and source records attributed to A M Shapiro.

79 records · Page 5Linked to original sources
PubMedDate not supplied

Porcine model of airway mucosal injury.

PURPOSE: The development of a reliable animal model of laryngeal or tracheal stenosis has been limited by lack of reproducibility, high morbidity and mortality, and cumbersome technique. The small size of previously proposed models has limited the development of innovative reconstructive techniques. MATERIALS AND METHODS: Eleven of 15 post-weanling commercial piglets underwent injury by a sharpened metal rod to the anterior half of the subglottic region at repeated intervals under endoscopic guidance. Four of 15 animals did not undergo injury and served as control for normal subglottic growth over time. Each airway was sized by endotracheal tube (ETT) passage and endoscopic photography over time, and the degree of total stenosis was estimated in comparison to the control animals. RESULTS: The first two animals underwent daily injury and expired from copious granulation tissue. Eight additional animals developed symptomatic subglottic stenosis manifested by audible stridor and intercostal retractions while undergoing injury every third day. Photographs documented the size of the stenosis to be greater than 50% (40% by ETT sizing) with a mean of three injuries in a mean time of 18 days. CONCLUSION: The porcine model shows a high degree of tolerance with minimal morbidity and consistent reliable results in an animal model of airway stenosis that is suitable for further innovative studies.

Animals↗
PubMedDate not supplied

High yield of rodent islets with intraductal collagenase and stationary digestion--a comparison with standard technique.

Intraductal distention of the pancreas with collagenase followed by stationary warm incubation improves the recovery of islets of Langerhans in the rat, but controlled studies are needed for valid comparison with standard isolation methods. We have modified Gotoh's technique of stationary digestion for high-yield isolation in the rat (Stationary). The method is subjected herein to rigorous blinded comparison with the standard chopped tissue (Chopped) technique, based on Lacy et al., as performed in our laboratory for over 10 yr. Islet recovery was determined by a single observe 'blinded' to the method of isolation used, and only intact islets of diameter > or = 100 microns were included. Stationary gave 719 +/- 114 islets per pancreas (mean +/- SD, n = 21 isolations) vs. 487.5 +/- 69 for Chopped (n = 36 isolations), a 47.5% increment in yield (p < 0.0001). In vitro islet perifusion showed no statistical difference in stimulation index (SI) or stimulated area under the curve (SAUC) between the two methods, but Stationary showed a trend towards improved phase II insulin release. In vivo function was assessed by isogeneic transplantation of 2,000 islets beneath the renal capsule of streptozotocin diabetic recipients (65 mg/kg Sigma); Stationary recipients (n = 7) became normoglycemic (< or = 8 mmol/L) by 3.3 +/- 4.8 days vs. 1.6 +/- 1.5 days for Chopped recipients (p = 0.4 ns, mean +/- SEM). IVGTT performed at 1 mo posttransplant gave K-values for Stationary of 2.64 +/- 0.8 vs. 2.62 +/- 0.8 for Chopped (mean +/- SD, p = 0.9 ns, n = 6, unpaired t-test), which were not distinguishable from normal control rats (2.59 +/- 0.8) (p = 0.9 ns, n = 10). Graft function remained stable until graft bearing nephrectomy induced hyperglycemia uniformly within 1 day. Graft histology showed a healthy well-preserved structure on light microscopy, with well-granulated beta cells on EM. Economic costs of rat, collagenase, and Ficoll were 26% ($50.82) lower per recipient for Stationary. We conclude that modified stationary digestion significantly improves islet recovery with excellent in vitro and in vivo function, and is cost effective.

Animals↗
PubMedDate not supplied

Intraductal collagenase delivery into the human pancreas using syringe loading or controlled perfusion.

Effective intraductal delivery of the enzyme collagenase into the pancreas is crucial to the subsequent ability to isolate viable islets. Most clinical islet transplant centers load the enzyme into the pancreas by retrograde injection using a syringe following cannulation of the pancreatic duct. An alternative approach is to perfuse the pancreas via the pancreatic duct with collagenase solution using a recirculating perfusion device system. This provides control over perfusion pressures and collagenase temperature. This study reports on our evaluation of the delivery of Liberase-HI into the pancreas of 14 consecutive adult multiorgan cadaveric donors. Alternate glands were procured and processed using an identical protocol with the exception of collagenase delivery. The first group of pancreases was loaded using the perfusion technique where cold (4 degrees C) Liberase-HI was perfused at 80 mmHg for 5 min after which the pressure was increased to 180 mmHg. The collagenase solution was then slowly warmed to 35 degrees C, transferred to the dissociation chamber and mechanically dissociated, and then purified using discontinuous gradients of Ficoll. Pancreases in the second group were loaded with collagenase (28-32 degrees C) using the syringe technique before mechanical dissociation and purification. There were no significant differences in pancreas cold ischemia, donor age, body mass index, maximum blood glucose, or serum amylase of the donors between the two groups. Mean collagenase digestion time in the digestion chamber was not different between the two groups; however, the amount of undigested tissue remaining after dissociation was significantly higher in the syringe-loaded group (15.3 +/- 2.6 g vs. 4.6 +/- 2.1 g, mean +/- SEM, p < 0.05). Postdigestion recovery of islets was 471 +/- 83 x 10(3) IE in the perfusion group compared with 391 +/- 57 x 10(3) IE for the syringe-loaded group. Postpurification recovery was higher in the perfused group (379 +/- 45 vs. 251 +/- 28 x 10(3) IE, p < 0.05, two-tailed paired t-test). No difference in in vitro islet viability was observed between the two groups following glucose perifusion with the calculated stimulation index of 4.6 +/- 0.6 for the perfusion group and 4.2 +/- 0.7 for the syringe-loaded group. Controlled perfusion via the pancreatic duct allows the effective delivery of the enzyme achieving maximal distension to all regions of the pancreas leading to an increased recovery of the islets with no detrimental effect on subsequent in vitro islet function.

Adenosine↗
PubMedDate not supplied

Liver tumor ablation techniques.

Despite advances in surgical technique, patients with primary and secondary liver tumors remain a difficult management problem, as most tumors are unresectable at presentation. Alternative therapies, involving the in situ destruction of liver tumors, have recently come under scrutiny as palliative options. Percutaneous ethanol injection and cryosurgery have been advocated, but both have associated technical difficulties and adverse effects. Novel liver tumor ablation techniques have recently been developed that work via the induction of localized hyperthermia. There is mounting evidence to support a hypothesis that cancer cells are more selectively sensitive to heat than are normal cells, due to the poor blood supply of neoplastic tissue and the decreased vasodilatation capacity of the neovascular bed. These ablative modalities induce a variable degree of tumor necrosis in unresectable tumors, and therefore may provide useful palliation. Clinical trials are needed to determine the true nature and degree of any palliative benefit. In addition, the determinants of treatment efficacy and the predictability of the necrotic zone must be better understood before these techniques can be contemplated as alternatives to liver resection for cure.

Cryosurgery↗
PubMedDate not supplied

[Mechanized system for planning technological processes].

A mechanized system for the production processes planning involving the use of an electronic code device for data preparation on a punched tape of the "EPECT-IT" type, at the base of which there are classifiers of standard operations and transitions to individual design members, is considered. A fragment of the classifier and a skeleton diagram of the system are presented. It is pointed out that the use of the system helps improve the quality of the design work, as well as to yield considerable economic advantages. The system is in operation at some enterprises of the medical engineering industry.

Electronic Data Processing↗