Localization of the peritoneal reflection in the pelvis by endorectal ultrasound

BACKGROUND

Large adenomas and low-risk rectal carcinomas (T1) that are localized distal of the pelvic peritoneal reflection (PPR) are treated by transanal excision. However, the location of the PPR varies widely and cannot be detected reliably by preoperative methods. Therefore, we evaluated the value of endorectal ultrasound (EUS) for the prediction of an intraperitoneal location of rectal tumors.

METHODS

Fourteen patients with rectal tumors measuring </=15 cm from the anal verge were examined by EUS. If peristalsis beyond the rectal wall or any intraperitoneal fluid was seen at the proximal tumor edge, the lesion was classified as localized above or in the level of the PPR. During the operation, the surgeon determined whether the upper end of the tumor reached the PPR.

RESULTS

In each of our 14 patients, the prediction by EUS was correct. In two patients, a small rectal tumor was excised with an electric sling during rectoscopy, but the polyp bases were not free of dysplastic epithelial tissue. The point where these two polyps were removed could be visualized by endoscopy but not by EUS. Once the relevant area was marked with a titanic endoclip, EUS was able to predict the resection place in relation to the PPR in these two patients as well.

CONCLUSIONS

Although this knowledge would be very important for the therapeutic strategy of small rectal tumors, it is impossible to determine the location of a rectal tumor with regard to the PPR either clinically or by endoscopy. EUS provides this information with high reliability. Thus, we recommend EUS as the method of choice for predicting the location of the PPR.

CREB1 encodes a nuclear activator, a repressor, and a cytoplasmic modulator that form a regulatory unit critical for long-term facilitation

Although CREB seems to be important for memory formation, it is not known which of the isoforms of CREB, CREM, or ATF1 are expressed in the neurons that undergo long-term synaptic changes and what roles they have in memory formation. We have found a single Aplysia CREB1 gene homologous to both mammalian CREB and CREM and have characterized in the sensory neurons that mediate gill-withdrawal reflex the expression and function of the three proteins that it encodes: CREB1a, CREB1b, and CREB1c. CREB1a is a transcriptional activator that is both necessary and, upon phosphorylation, sufficient for long-term facilitation. CREB1b is a repressor of long-term facilitation. Cytoplasmic CREB1c modulates both the short- and long-term facilitation. Thus, in the sensory neurons, CREB1 encodes a critical regulatory unit converting short- to long-term synaptic changes.

MEN1 gene mutations in 12 MEN1 families and their associated tumors

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited tumor syndrome characterized by the development of multiple endocrine tumors. The gene responsible for the disease, termed MEN1 gene. has recently been isolated and germline mutations have been described in affected MEN1 individuals. Twelve unrelated (German MEN1 families and their associated tumors (5 parathyroid tumors, 1 vipoma, 1 gastrinoma, 1 insulinoma) were characterized for MEN1 gene mutations by single-strand conformational variant (SSCV) analysis and DNA sequence analysis as well as for loss of heterozygosity on chromosome 11q13. We identified nine different heterozygous germline mutations (6 frameshift, 2 missense, 1 nonsense), eight of them were novel. Four of five informative MEN1-associated tumors revealed deletion of the second MEN1 allele, supporting the concept of a tumor suppressor gene. Furthermore. SSCV analysis proved an effective and sensitive method for the detection of menin mutations providing a reliable genetic screening approach supporting genetic counseling and clinical management of MEN1 family members.

Localization, malignant potential, and surgical management of gastrinomas

Between 1987 and 1996 a total of 25 patients with proved Zollinger-Ellison syndrome (ZES) have been treated in our department. If preoperative imaging studies did not show diffuse metastatic disease, patients were scheduled for operation with a standardized surgical approach including thorough exploration and intraoperative ultrasonography (IOUS) of the pancreas and a longitudinal duodenotomy, with separate palpation of the anterior and posterior walls. Postoperatively, patients were followed up by physical examination, fasting gastrin levels, and the secretin stimulation test. Altogether 10 patients had duodenal wall gastrinoma, 14 patients pancreatic gastrinoma, and the tumor was not found in 1 patient. Only 15 tumors (60%) (2 duodenal wall and 13 pancreatic gastrinomas) could be visualized preoperatively. Intraoperatively, 24 of 25 primary gastrinomas were localized. The mean size of duodenal wall gastrinomas (9.6 mm) was significantly smaller than that of pancreatic gastrinomas (28.7 mm) (p < 0.05). At the time of surgical exploration, five duodenal and seven pancreatic gastrinomas had metastasized. The incidence of lymph node metastases was similar for both tumor sites, whereas patients with pancreatic gastrinomas more frequently had liver metastases. The presence of liver metastases was the most important determinant for survival. Four patients (40%) with duodenal and seven with pancreatic (50%) gastrinomas (mean follow-up 5.2 years) were biochemically cured by operation. Of the remaining patients, eight are still alive with recurrent disease. Our results suggest that preoperative localization of gastrinomas often fails despite all modern imaging methods. Therefore a standardized surgical exploration of the pancreas including IOUS and a duodenal exploration should be performed to achieve optimal results. Preoperative diagnostic imaging tests should include computed tomography, ultrasonography, and somatostatin receptor scintigraphy to exclude diffuse metastases. In contrast to liver metastases, lymph node metastases do not have a significant influence on survival.

K-ras oncogene mutations indicate malignancy in cystic tumors of the pancreas

OBJECTIVE

To evaluate clinical parameters, presurgical diagnostic tests, histologic findings, and the presence of K-ras oncogene mutations in cystic tumors of the pancreas to determine which best predict malignancy.

SUMMARY BACKGROUND DATA

Because presurgical, intraoperative, and final pathologic differentiation is difficult in cystic tumors of the pancreas, it would be a major benefit to identify markers that accurately predict malignancy in these rare tumors. The role of K-ras oncogene mutations as an indicator of malignancy has not been determined in these tumors.

METHODS

Nineteen patients with cystic tumors of the pancreas were evaluated, including K-ras mutation analysis based on polymerase chain reaction and restriction digestion assays and direct DNA sequencing, to screen for parameters that accurately predict malignancy.

RESULTS

All malignant cystic pancreatic tumors (five cystadenocarcinomas and three mucin-producing adenocarcinomas) harbored K-ras mutations at codon 12 or 13. K-ras mutations were also detected in the percutaneous fine-needle aspirates of two of these patients. In contrast, none of nine benign cystadenomas or the solid-papillary neoplasm had K-ras mutations. None of the patients with a benign tumor carrying K-ras wild-type sequences developed recurrent disease after a mean follow-up of 50 months. Seven of the 8 malignant cystic pancreatic tumors, but none of the 11 benign tumors, showed dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography.

CONCLUSIONS

K-ras mutation analysis seems to be a powerful tool to determine the malignant potential of cystic pancreatic tumors before and after surgery. Dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography is highly suggestive for malignancy in these rare tumors.

Identification of a gene encoding a hyperpolarization-activated pacemaker channel of brain

The generation of pacemaker activity in heart and brain is mediated by hyperpolarization-activated cation channels that are directly regulated by cyclic nucleotides. We previously cloned a novel member of the voltage-gated K channel family from mouse brain (mBCNG-1) that contained a carboxy-terminal cyclic nucleotide-binding domain (Santoro et al., 1997) and hence proposed it to be a candidate gene for pacemaker channels. Heterologous expression of mBCNG-1 demonstrates that it does indeed code for a channel with properties indistinguishable from pacemaker channels in brain and similar to those in heart. Three additional mouse genes and two human genes closely related to mBCNG-1 display unique patterns of mRNA expression in different tissues, including brain and heart, demonstrating that these channels constitute a widely expressed gene family.

[Oncologic risk in pylorus preservation in resection of ductal pancreas carcinoma]

We detected peripyloric lymph node metastasis in 2 of 24 patients with ductal adenocarcinoma of the pancreas who underwent Kausch-Whipple's procedure. The resection would have been palliative if these patients were treated by pylorus-preserving pancreatoduodenectomy.

Nuclear matrix attachment regions of human papillomavirus type 16 point toward conservation of these genomic elements in all genital papillomaviruses

The gene functions, transcriptional regulation, and genome replication of human papillomaviruses (HPVs) have been extensively studied. Thus far, however, there has been little research on the organization of HPV genomes in the nuclei of infected cells. As a first step to understand how chromatin and suprachromatin structures may modulate the life cycles of these viruses, we have identified and mapped interactions of HPV DNAs with the nuclear matrix. The endogenous genomes of HPV type 16 (HPV-16) which are present in SiHa, HPKI, and HPKII cells, adhere in vivo to the nuclear matrixes of these cell lines. A tight association with the nuclear matrix in vivo may be common to all genital HPV types, as the genomes of HPV-11, HPV-16, HPV-18, and HPV-33 showed high affinity in vitro to preparations of the nuclear matrix of C33A cells, as did the well-known nuclear matrix attachment region (MAR) of the cellular beta interferon gene. Affinity to the nuclear matrix is not evenly spread over the HPV-16 genome. Five genomic segments have strong MAR properties, while the other parts of the genome have low or no affinity. Some of the five MARs correlate with known cis-responsive elements: a strong MAR lies in the 5' segment of the long control region (LCR), and another one lies in the E6 gene, flanking the HPV enhancer, the replication origin, and the E6 promoter. The strongest MAR coincides with the E5 gene and the early-late intergenic region. Weak MAR activity is present in the E1 and E2 genes and in the 3' part of L2. The in vitro map of MAR activity appears to reflect MAR properties in vivo, as we found for two selected fragments with and without MAR activity. As is typical for many MARs, the two segments with highest affinity, namely, the 5' LCR and the early-late intergenic region, have an extraordinarily high A-T content (up to 85%). It is likely that these MARs have specific functions in the viral life cycle, as MARs predicted by nucleotide sequence analysis, patterns of A-T content, transcription factor YY1 binding sites, and likely topoisomerase II cleavage sites are conserved in similar positions throughout all genital HPVs.

Frequent abnormalities of the putative tumor suppressor gene FHIT at 3p14.2 in pancreatic carcinoma cell lines

The FHIT gene is localized on chromosome 3p14, a region including a tumor cell-specific, commonly deleted region. To determine the role of the FHIT gene in pancreatic carcinogenesis, 14 pancreatic carcinoma cell lines were analyzed by reverse transcription-PCR and exon-specific PCR amplification of genomic DNA. The full-length FHIT transcript was lost in 70% of the pancreatic carcinoma cell lines analyzed, while 66% also revealed intragenic homozygous deletions of exons 3, 4, and 5. Truncated FHIT transcripts lacking a variable number of exons most likely represented alternative splicing products. Fhit protein expression was dependent on a full-length FHIT transcript. The results suggest that the FHIT gene may be a target tumor suppressor gene involved in pancreatic carcinogenesis.

Mutations of the DPC4/Smad4 gene in biliary tract carcinoma

A candidate tumor suppressor gene, DPC4, located at 18q21.1, has recently been shown to be inactivated in half of pancreatic adenocarcinomas. The close developmental relationship of the pancreas and biliary tract prompted us to determine the role of DPC4 in the multistep carcinogenesis of biliary tract carcinoma. A search for mutations in the genomic sequence of the highly conserved COOH-terminal domain of DPC4 (exons 8-11) was performed by single-strand conformational polymorphism analysis. Five of 32 (16%) primary biliary tract carcinomas had point mutations in the DPC4 sequence. Interestingly, inactivation of DPC4 was especially common in carcinomas originating from the common bile duct (four of eight specimens analyzed), suggesting an important role for DPC4 in the development of this subtype of biliary tract tumor.

Memory suppressor genes: inhibitory constraints on the storage of long-term memory

Synaptic plasticity, the ability of neurons to alter the strength of their synaptic connections with activity and experience, is thought to play a critical role in memory storage. Molecular studies of gene expression during long-lasting synaptic plasticity related to memory storage initially focused on the identification of positive regulators. More recent work has revealed that the establishment of long-lasting synaptic plasticity and long-term memory also requires the removal of inhibitory constraints. By analogy to tumor suppressor genes, which restrain cell proliferation, we propose that these inhibitory constraints of memory storage, which restrain synapse growth, be termed memory suppressor genes.

[Detection of hepatic micrometastasis in ductal pancreatic carcinoma by K-ras mutation analysis and determination of clinical relevance]

In this prospective study we evaluated the presence and importance of hepatic micrometastases at the time of operation in patients with resectable pancreatic carcinoma. In 13 patients with pancreatic carcinoma and 5 patients with chronic pancreatitis Truecut-Needle biopsies of the liver were obtained during operation. K-ras mutation analysis was done by the PCR/restriction digestion assay with HphI, followed by an ultrasound of the liver in 3 monthly intervals. Four of 13 (30%) pancreatic cancer patients had K-ras gene mutations in the liver and had a mean survival of 6 months after resection. All chronic pancreatitis patients and 8 of the 9 remaining pancreatic cancer patients without K-ras mutations in the liver biopsies are alive without evidence of liver metastases after a mean follow-up of 9 months. Detection of micrometastases in the liver by K-ras mutation analysis might be a powerful tool to identify occult clinical relevant liver metastases.

Interactive cloning with the SH3 domain of N-src identifies a new brain specific ion channel protein, with homology to eag and cyclic nucleotide-gated channels

We have isolated a novel cDNA, that appears to represent a new class of ion channels, by using the yeast two-hybrid system and the SH3 domain of the neural form of Src (N-src) as a bait. The encoded polypeptide, BCNG-1, is distantly related to cyclic nucleotide-gated channels and the voltage-gated channels, Eag and H-erg. BCNG-1 is expressed exclusively in the brain, as a glycosylated protein of approximately 132 kDa. Immunohistochemical analysis indicates that BCNG-1 is preferentially expressed in specific subsets of neurons in the neocortex, hippocampus, and cerebellum, in particular pyramidal neurons and basket cells. Within individual neurons, the BCNG-1 protein is localized to either the dendrites or the axon terminals depending on the cell type. Southern blot analysis shows that several other BCNG-related sequences are present in the mouse genome, indicating the emergence of an entire subfamily of ion channel coding genes. These findings suggest the existence of a new type of ion channel, which is potentially able to modulate membrane excitability in the brain and could respond to regulation by cyclic nucleotides.

[Results of a standardized treatment concept in primary hyperparathyroidism]

BACKGROUND AND OBJECTIVE

Primary hyperparathyroidism (PHPT) is being diagnosed ever more frequently. After diabetes mellitus, ovarian dysfunction and metabolic disorders it is now among the most frequent metabolic disease. Its surgical treatment has become standardized with increasing experience. A prospective study was undertaken to clarify to what extent our own standardized diagnostic and therapeutic measures conform to current standards in literature.

PATIENTS AND METHODS

During 10 years (1. 1. 1987-31. 12. 1996) 478 patients with PHPT were treated surgically (solitary adenoma: 317 (76.5%), multiple lobe hyperplasias 66 (15.9%), double adenoma 28 (6.8%), and carcinoma 4 (0.8%). PHPT was part of the MEN (multiple endocrine neoplasia) syndrome in 20 patients. Typical symptoms of PHPT had been present in 400 patients (83.7%), while 78 (16.3%) had no manifest symptoms. Ultrasound examination of the soft tissues was the only preoperative test of localization. More extensive preoperative diagnosis was practised only before reoperations. All patients had bilateral exploration of the neck to try and demonstrate all four epithelial bodies.

RESULTS

A primary operation normalized the calcium level in 405 of 414 patients (97.8%). In 64 previously unsuccessfully operated patients who were reoperated for persisting HPT the elevated calcium levels could be normalized in 90.6%. Hypercalcaemia was finally abolished in all 478 patients. Average follow-up duration for 319 patients was more than 4.8 (0.5-8.5) years. The perioperative mortality rate was 0.8 (4 of 478), with 41 deaths during the later follow-up period. Permanent recurrent laryngeal nerve palsy occurred in 6 patients (1.8%). Long-term calcium substitution was necessary postoperatively in four patients (1.2%).

CONCLUSION

Our findings support a liberal policy towards indication for bilateral surgical exploration of the neck in PHPT.

[Intraoperative cholangiography as a routine method? A prospective, controlled, randomized study]

A prospective, controlled, randomized trial was conducted in 275 patients with symptomatic gall stone disease, whose history, laboratory data or sonographical findings did not suggest common bile duct stones. Of these patients, 137 did not undergo intraoperative fluoroscopic cholangiography (IOC), but in the remaining 138 patients IOC was attempted. In 111 cases (80.4%) the biliary system was sufficiently visualized. In 3 patients (2.7%) calculi in the cystic or common bile duct were diagnosed, which would have been overlooked without IOC. IOC was false-positive in one case. One year after the operation the patients were asked to return for a follow-up examination. Three patients in the group without IOC had had symptomatic passage of a stone, and one had a common bile duct stone removed by endoscopic papillotomy. A retained stone was discussed as etiology for a pancreatitis in a fifth patient in this group. No patient sustained long-term sequelae from the retained common bile duct stones. None of the patients in the IOC group had evidence of cholangiolithiasis at follow-up. There was no difference between the study groups concerning the incidence of post-operative complications. The operations with IOC lasted significantly longer (92 +/- 31 min vs 77 +/- 28 min). According to our data and those published earlier, the additional financial and logistic expenditure associated with routine IOC is not justified. Patients with the preoperative suspicion of a common bile duct stone should have endoscopic bile duct clearance (ERCP and EPT) prior to cholecystectomy.

The value of somatostatin-receptor scintigraphy in newly diagnosed endocrine gastroenteropancreatic tumors

BACKGROUND

Conventional imaging techniques do not routinely detect endocrine gastroenteropancreatic tumors preoperatively. The purpose of this study was to determine whether the new technique of somatostatin-receptor scintigraphy would improve the detection rate of these tumors before initial treatment.

STUDY DESIGN

In a prospective study, 55 patients with a recent diagnosis of endocrine gastroenteropancreatic tumors (22 intestinal carcinoids, 17 gastrinomas, 10 nonfunctioning pancreatic tumors, and 6 insulinomas), were examined with somatostatin-receptor scintigraphy, computed tomography, and ultrasonography. Results of the three imaging modalities were compared with findings at surgical exploration.

RESULTS

None of the insulinomas were localized by somatostatin-receptor scintigraphy, but 4 of 6 insulinomas were detected by computed tomography and ultrasonography. Of 17 gastrinomas, 9 were detected by somatostatin-receptor scintigraphy; computed tomography and ultrasonography localized only 7. Metastases from the gastrinoma were localized by somatostatin-receptor scintigraphy in all cases; computed tomography and ultrasonography detected metastases in only 6 of 9 patients. Nonfunctioning tumors could be localized by somatostatin-receptor scintigraphy, computed tomography, and ultrasonography in 4, 7, and 8 of 10 cases, respectively. Detection rate for corresponding metastases was the same for all three imaging techniques. Primary carcinoids were identified by somatostatin-receptor scintigraphy, ultrasonography, and computed tomography in 7, 8, and 11 of 22 cases, respectively. Extra-abdominal metastases were detected by somatostatin-receptor scintigraphy in only 7 of 19 patients.

CONCLUSIONS

In patients with insulinomas, somatostatin-receptor scintigraphy is not indicated because none of the six tumors was imaged. This holds true for nonfunctional pancreatic endocrine tumors and their metastases because no advantage for somatostatin-receptor scintigraphy was found over computed tomography and ultrasonography. In contrast, somatostatin-receptor scintigraphy is superior to computed tomography and ultrasonography for determining the extent of the disease in patients with gastrinomas or carcinoids. The problem of detecting primary tumors in these patients is not solved by somatostatin-receptor scintigraphy.

Surgical management of hyperparathyroidism in patients with multiple endocrine neoplasia type 2A

BACKGROUND

The surgical management of hyperparathyroidism in patients with multiple endocrine neoplasia type 2A (MEN 2A) is controversial. We report the long-term follow-up, mutational analysis, and surgical outcome in a large group of patients with MEN 2A and hyperparathyroidism.

METHODS

Clinical and genetic data for MEN 2A patients with biochemically and pathologically confirmed hyperparathyroidism and a minimum of 5 years of follow-up were analyzed retrospectively, and outcomes after surgical management were compared.

RESULTS

Thirty-five (29%) of 119 patients from 14 MEN 2A kindreds had biochemical and pathologic evidence of hyperparathyroidism, with a mean follow-up of 14.7 years. The phenotypic expression of hyperparathyroidism was associated with germline mutations of the RET protooncogene at codons 634 and 618. At initial operation, 21 (62%) patients had a selective resection, eight (24%) had a subtotal resection, five (14%) had total parathyroidectomy with autotransplantation, and one had an inadvertent total parathyroidectomy. Twenty-seven (77%) patients were cured by the first operation. Persistent hyperparathyroidism occurred in three (8.6%) patients, and recurrent hyperparathyroidism occurred in five (14.3%) patients; both occurred only in patients treated with selective or subtotal resection. Permanent postoperative hypoparathyroidism occurred in six (21%) of 29 patients after selective or subtotal resection, in the one patient with inadvertent total parathyroidectomy, and in one (20%) of 5 patients treated with total parathyroidectomy and autotransplantation.

CONCLUSIONS

Recurrent or persistent hyperparathyroidism occurs after selective or subtotal parathyroidectomy, as a result of either missed glands or interval development of neoplasia in previously normal parathyroid glands left in situ. Therefore we advocate total parathyroidectomy and heterotopic autotransplantation for patients with hyperparathyroidism and MEN 2A.

Toward a molecular definition of long-term memory storage

The storage of long-term memory is associated with a cellular program of gene expression, altered protein synthesis, and the growth of new synaptic connections. Recent studies of a variety of memory processes, ranging in complexity from those produced by simple forms of implicit learning in invertebrates to those produced by more complex forms of explicit learning in mammals, suggest that part of the molecular switch required for consolidation of long-term memory is the activation of a cAMP-inducible cascade of genes and the recruitment of cAMP response element binding protein-related transcription factors. This conservation of steps in the mechanisms for learning-related synaptic plasticity suggests the possibility of a molecular biology of cognition.

Mxi1 tumor suppressor gene is not mutated in primary pancreatic adenocarcinoma

Amplification of the c-myc oncogene occurs in a variety of solid tumors, including pancreatic adenocarcinomas. The MXI1 gene, located at 10q24-q25, may serve to negatively regulate c-myc oncogene activity, and potentially has tumor suppressor function. As such, altered MXI1 function might contribute to tumorigenesis. We examined 40 primary human pancreatic adenocarcinomas for MXI1 mutations. Single-strand conformation variant analysis and direct sequencing of the variants revealed a MXI1 polymorphism in 1 of 40 tumors. No MXI1 mutations were identified. Southern blot analyses did not reveal any gross rearrangements of MXI1. These results suggest that MXI1 is unlikely to play a role in human pancreatic adenocarcinoma tumorigenesis.

Infrequent CDKN2 mutation in human differentiated thyroid cancers

We examined the frequency of cyclin-dependent kinase (CDK) N2 alterations in differentiated and anaplastic thyroid cancers to assess the involvement of CDKN2 in the development of these cancers. The CDKN2 gene, which encodes the cell-cycle regulator p16, was recently shown to be mutated or deleted in many tumor cell lines. Its role in the genesis of primary tumors is uncertain, however. Tumor and corresponding normal DNAs were prepared by microdissection of paraffin-embedded tissue blocks or from frozen surgical specimens of 15 papillary, 15 follicular, and five anaplastic thyroid carcinomas. The entire CDKN2 coding region was screened by single-strand conformational variant analysis and direct sequencing of variants. The presence of homozygous deletions was evaluated by multiplex polymerase chain reaction (PCR) analysis. Loss of heterozygosity (LOH) in the CDKN2 region was assessed by using flanking polymorphic markers. Two somatic missense mutations were found among the 35 thyroid cancers, one in a follicular tumor and one in an anaplastic tumor. Multiplex PCR suggested the presence of homozygous deletion in one anaplastic tumor and hemizygous deletions in four tumors. LOH studies revealed loss of 9p sequences in four follicular (27%) and two anaplastic (50%) cancers. Our data suggest that alterations in CDKN2 played a role in a minority of thyroid cancers (three of 35). LOH in the region of CDKN2 is seen in a significant proportion of follicular and anaplastic but not papillary cancers. Loss of 9p sequences suggests a role for a tumor suppressor gene in the development of follicular and anaplastic thyroid cancers.

Aplysia CREB2 represses long-term facilitation: relief of repression converts transient facilitation into long-term functional and structural change

The switch from short- to long-term facilitation induced by behavioral sensitization in Aplysia involves CREB-like proteins, as well as the immediate-early gene ApC/EBP. Using the bZIP domain of ApC/EBP in a two-hybrid system, we have cloned ApCREB2, a transcription factor constitutively expressed in sensory neurons that resembles human CREB2 and mouse ATF4. ApCREB2 represses ApCREB1-mediated transcription in F9 cells. Injection of anti-ApCREB2 antibodies into Aplysia sensory neurons causes a single pulse of serotonin (5-HT), which induces only short-term facilitation lasting minutes, to evoke facilitation lasting more than 1 day. This facilitation has the properties of long-term facilitation: it requires transcription and translation, induces the growth of new synaptic connections, and occludes further facilitation by five pulses of 5-HT.

Proteins functioning in synaptic transmission at the sensory to motor synapse of Aplysia

Over expression of Aplysia synaptotagmin in acutely dissected cholinergic neurons from the buccal ganglia, or in primary co-cultures of glutaminergic sensory neurons and motor neurons, causes a reduction synaptic transmission. Anti-sense oligonucleotide treatment of similar cultures produced an enhancement of synaptic transmission. The interaction between Aplysia VAMP/synaptobrevin and syntaxin is reconstructed using the yeast two hybrid system, and used to identify amino acid residues of VAMP/synaptobrevin that are required for this interaction. Point mutations around residue 50, close to the site of cleavage by botulinum toxins specifically disrupt the interaction with syntaxin. An additional VAMP/synaptobrevin binding protein, VAP33, is identified using the yeast two hybrid system. Intracellular injection of VAP33 specific antisera inhibits synaptic transmission in sensory-motor neuron co-cultures.