Abstract. The superpotential in the Landau-Ginzburg construction of solutions to the Witten-Dijkgraaf-Verlinde-Verlinde (or WDVV) equations is modified to include logarithmic terms. This results in deformations -quadratic in the deformation parameters -of the normal prepotential solution of the WDVV equations. Such solution satisfy various pseudo-quasi-homogeneity conditions, on assigning a notional weight to the deformation parameters. This construction includes, as a special case, deformations which are polynomial in the flat coordinates, resulting in a new class of polynomial solutions of the WDVV equations.

Bi-Hamiltonian structures involving Hamiltonian operators of degree 2 are studied. Firstly, pairs of degree 2 operators are considered in terms of an algebra structure on the space of 1-forms, related to so-called Fermionic Novikov algebras. Then, degree 2 operators are considered as deformations of hydrodynamic type Poisson brackets.

This paper reports techniques for the isolation and long term preservation of pancreatic islets from the mouse, rat and guinea pig. Islets have been isolated using a modification of a free hand microdisection procedure described by Hellerström in 1964 [1]. Isolated islets have been subjected to three preservation systems and their viability following storage assessed by light microscopy of sections stained with Gomor's aldehyde fuchsin [2] and by measuring the insulin release from islets in vitro in response to a glucose stimulus. The systems were: a) Simple cold storage in Hank's balanced salt solution at 4 degrees C. Following 15 h cold storage, histological and functional survival was 100%. This dropped to 10% at 48 h. There were no survivors following 72 h storage. b) Sub zero cell storage. In Group I (freezing rate 1 degrees C/min) histological survival was 35% and functional survival 20%. In Group II (freezing rate 5 degreees C/min with 24 h culture period after rewarming) histological survival was approximately 87% and functional survival 75%. c) Organ Culture. Islets from the guinea pig, rat and mouse showed minimal morphologic damage when cultured for 21 days in a simple organ culture system. At 28 days, histological survial was approximately 30%. Following organ culture we were unable to correlate histological and functional survival.

Viable islets of Langerhans have been isolated from the mouse, rat, guinea-pig and human pancreas using a free hand microdissection procedure. Viablity has been assessed by light microscopy of sections stained with Gomori's aldehyde fuchsin and by measuring the insulin release from islets in vitro in response to a glucose stimulus. Ten pieces of human cadaver pancreas have been studied. Islets were isolated from 6 and in 5 cases were shown to respond to a glucose stimulus in vitro. Five pieces of human pancreas removed at operation have been studied. Islets were isolated in all cases but only 2 showed a response to a glucose stimulus. Isolated animal islets have been subjected to three preservation systems and their viability following storage noted. 1. Simple cold storage in Hank's balanced salt solution at 4 degrees C. At 15 hours 100% survival was noted. This dropped to 10% at 48 hours. There were no survivors at 72 hours. 2. Subzero storage. In group I (freezing rate 1 degree C/min) histological survival was 35% and functional survival 20%. In group II (freezing rate 5 degrees C/min with a 24-hour culture period after rewarming) histological survival was approximately 87% and functional survival 75%. 3. Organ culture. Islets from the guinea-pig, rat and mouse showed minimal morphological damage when cultured for 21 days in a simple organ culture system. At 28 days histological survival was approximately 30%. We were unable to correlate histological and functional survival in this group.

This article reports a method for the isolation of viable pancreatic islets from the human pancreas. Isolated islets were obtained from human pancreata of cadavers, patients undergoing surgical operations, and fetuses, using a freehand microdissection procedure. Viability was assessed by light microscopy of sections stained with aldehyde fuchsin and by measuring the insulin output of islets in response to a glucose stimulus in vitro using a perifusion system. Ten pieces of cadaver pancreas were studied. Islets were isolated from 6 specimens and in 5 of these were shown to respond to a glucose stimulus in vitro. Histologically the islets showed minimal damage with slight degranulation of the beta cells. Five pieces of pancreas removed at operation were studied as well. Islets were isolated in all cases, but only 2 showed a response to a glucose stimulus. Pancreata from a 26-week and 34-week human fetus were also studied. It was not possible to microdissect islets from either case, but small pieces of pancreas from the 26-week fetus were shown to respond to a glucose stimulus by producing a significant increase in insulin output.