A patient with a metastatic gastroenteropancreatic endocrine carcinoma causing hyperinsulinaemic hypoglycaemia and the carcinoid syndrome.

We present the case of a 57-year-old patient who initially presented with a constellation of symptoms including intense pruritis, flushing and diarrhoea. Following several months clinical deterioration, the patient was investigated radiologically, where multiple hepatic tumours were identified. Liver biopsy confirmed the presence of a well-differentiated metastatic gastroenteropancreatic endocrine carcinoma with biochemical evidence of serotonin secretion. Over a period of six months, the clinical course of the patient's disease progressed whereby severe hypoglycaemia became the major manifestation. Subsequent biochemical investigations confirmed the diagnosis of an insulinoma. Extensive radiological investigation revealed a solitary primary pancreatic tumour, indicating the presence of a metastatic pancreatic endocrine tumour (PET) secreting both insulin and serotonin. The patient was treated with a chemotherapy regimen consisting of 12 cycles of 5-fluorouracil/oxaliplatin, responding clinically - improved World Health Organization performance score from 3 to 1, biochemically - significantly reduced plasma chromogranin A and cancer antigen 19-9 concentrations and improved liver function tests, and radiologically - reduced pancreatic and hepatic tumour size. This is the first report of a primary PET secreting insulin and serotonin. Due to the association of serotonin-secreting gastroenteropancreatic endocrine tumours (GEP-ETs) with multiple endocrine neoplasia type-1 (MEN1) and biochemical evidence of an insulinoma, MEN1 should also be considered in such cases. The case provides further evidence for the biological heterogeneity of GEP-ETs and the myriad secretory humoral products and resultant clinical syndromes arising from such tumours.

Expression of the Aspergillus niger glucose oxidase gene in A. niger, A. nidulans and Saccharomyces cerevisiae.

We report the cloning of the Aspergillus niger glucose oxidase gene and its use to elevate glucose oxidase productivity in A. niger by increasing the gene dosage. In addition, the gene has been introduced into A. nidulans where it provides the novel capacity to produce glucose oxidase. A plasmid, in which DNA encoding the mature form of glucose oxidase was preceded by a Saccharomyces cerevisiae secretion signal, effected high-level production of extracellular glucose oxidase in this yeast.

A novel class of vector for yeast transformation.

We have constructed a set of hybrid yeast Escherichia coli vectors which utilise the site specific recombination function of the Saccharomyces cerevisiae 2 microns plasmid to completely eliminate the bacterial moiety upon introduction into yeast. A number of these plasmids have been shown to exhibit high inheritable stability in both laboratory and industrial strains during non-selective growth. These plasmids are beneficial for the genetic modification of industrial yeast, particularly those used in the production of food and beverages, and are of benefit in the study of plasmid maintenance and heterologous gene expression.

Cloning and expression of a Bacillus subtilis Endo-1,3-1,4-beta-D-glucanase gene in Escherichia coli K12.

EcoRI fragments of DNA from Bacillus subtilis NCIB 8565, a high producer of an endo-1,3-1,4-beta-D-glucanase, were 'shot-gun' cloned in the plasmid vector pBR325. A 3.5 kb insert, carrying single restriction sites for AvaI, BglII, ClaI, PvuI and PvuII, was shown to direct the synthesis of beta-glucanase in Escherichia coli K12. Enzyme activity was demonstrated in extracellular fractions of E. coli harbouring the beta-glucanase gene; however, the largest proportion (greater than 50%) of total enzyme activity was periplasmic in location. beta-Glucanase activity and cellular location were independent of the orientation of the 3.5 kb fragment in pBR325.

Expression of the cloned endo-1,3-1,4-ß-glucanase gene of Bacillus subtilis in Saccharomyces cerevisiae.

A cloned endo-1,3-1,4-ß-glucanase gene from the Gram-positive bacterium B. subtilis has been located by deletion analysis on a 1.4 kb PvuI-ClaI DNA fragment. This gene has been sub-cloned in the yeast LEU2 vector pJDB207 to produce a hybrid plasmid designated pEHB9. pEHB9 has been transformed to S. cerevisiae and shown to direct the synthesis of an endo-1,3-1,4-ß-glucanase in yeast. The ß-glucanase activity was low and could only be detected in crude cell extracts of yeast harbouring pEHB9.

Escherichia coli minichromosomes containing the pSC101 partitioning locus are stably inherited.

The par region of pSC101, required in cis to promote its stable inheritance, was joined, in combination with the tetr determinant of pBR325, to large and small minichromosomes. These hybrid minichromosomes were examined for stability and found to be no more stable than their parent minichromosomes. Indeed, one recombinant plasmid, pEH21, showed reduced stability, which was not attributable to a reduced copy number. Neither pEH21 nor pEH22, a plasmid composed of the same DNA arranged differently, was stabilized by the presence of a Par+ pSC101 derived replicon in the same cell. We conclude that the par region of pSC101 does not stabilize minichromosomes.

Restriction mediated by pAV2 affects the transfer of plasmids in Acinetobacter calcoaceticus.

The naturally occurring plasmid pAV2 restricts the entry of the P class plasmid RP4 and the W class plasmids R388 and S-a into Acinetobacter calcoaceticus strain EBF65/65 from Escherichia coli. The W class plasmids only transfer from E. coli into pAV2-strains. Plasmid RP4 is modified in the presence of pAV2 such that it is no longer restricted on entry into pAV2 recipients of strain EBF65/65.

Naturally occurring plasmids in Acinetobacter calcoaceticus: pAV2, a plasmid which influences the fertility of the sex factor pAV1.

Acinetobacter calcoaceticus strain EBF65/65 harbours a cryptic plasmid, pAV2, which has been shown by electrophoretic separation on agarose gels to have a molecular mass of approximately 13.5 megadaltons (Md). Transfer of the previously described sex factor pAV1 (Hinchliffe & Vivian, 1980 a,b) from the hospital strainJC17 into strains possessing pAV2 occurs only at a low frequency, whereas transfer to similar strains lacking pAV2 occurs at a much higher frequency. In EBF65/65, pAV1 may be present in strains possessing or lacking pAV2; pAV1 strains lacking pAV2 correspond to strains previously described as pAV1a (Hinchliffe & Vivian, 1980b) whereas pAV1 strains which also possess pAV2 correspond to pAB1b strains. The genetic evidence presented here is consistent with the hypothesis that pAV2 specifies a host restriction and modification system that is active against pAV1. Physical evidence from agarose gel electrophoresis indicates that pAV1 corresponds to a band of approximately 85 Md in strain JC17. The corresponding band in strains of EBF65/65 is difficult to distinguish because of the presence of a further cryptic plasmid band of approximately 88 Md, designated pAV3. A small cryptic plasmid of approximately 6 Md, designated pAV4, is reported for EBF65/65.

Gene transfer in Acinetobacter calcoaceticus: fertility variants of the sex factor pAV1.

The naturally occurring transmissible plasmid pAV1 mediates chromosome transfer and can exhibit two distinct levels of transmissibility in Acinetobacter calcoaceticus strain EBF65/65. The two states of pAV1 have been arbitrarily designated pAV1a (low frequency variant) and pAV1b (high frequency variant). Both variants have the same incompatibility and host range properties and each mobilizes two non-transmissible resistance determinants for tetracycline and neomycin. Sex factor activity has been shown to be stable: however, pAV1b fertility variants can be derived from pAV1a donors following conjugal transfer of pAV1 into new recipient strains of EBF65/65.

Naturally occurring plasmids in Acinetobacter calcoaceticus: a P class R factor of restricted host range.

A naturally occurring transmissible plasmid, designated pAV1, has been isolated in Acinetobacter calcoaceticus. It specifies resistance to sulphonamides and is capable of mobilizing two non-transmissible resistance determinants for tetracycline and neomycin, respectively, within strains of A. calcoaceticus. It is incompatible with the P class R factors RP4 and R751 in A. calcoaceticus. On this basis we conclude that pAV1 is a member of the P incompatibility group. However, unlike most other P group R factors, pAV1 is not transmissible to strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella or Proteus mirabilis.