Ammonia as an accelerator of tumor necrosis factor alpha-induced apoptosis of gastric epithelial cells in Helicobacter pylori infection

The mechanism by which Helicobacter pylori induces apoptosis remains unclear. In a previous study using biopsy samples, we found a significant correlation between the urease activity of an H. pylori strain and the apoptosis level induced by this strain. Therefore, in this study, we investigated whether urease and/or the ammonia generated by urease can induce apoptosis. Human gastric epithelial cell lines were cocultured with H. pylori, and the levels of apoptosis and ammonia production were measured. The medium was supplemented (or not supplemented) with urea and cytokines. While a large amount of ammonia (>30 mM) accumulated in the coculture containing urease-positive H. pylori and urea, no significant degree of apoptosis occurred. In the presence of tumor necrosis factor alpha (TNF-alpha), however, a marked acceleration of apoptosis was found in this coculture. Such enhancement of apoptosis was also induced by the addition of 4 to 8 mM ammonia to the cell culture without either H. pylori or urea but containing TNF-alpha. These results suggested that ammonia accelerates cytokine-induced apoptosis in gastric epithelial cells, while ammonia or urease molecules alone are unable to induce a significant degree of apoptosis.

Nitrous oxide, but not xenon, affects the signaling in the neuronal growth cone

1. Xenon (Xe) is an inert gas with the anesthetic property. To investigate whether Xe affects the neural network formation, the authors examined the biochemical characteristics of growth cones prepared from rat forebrains at different perinatal periods, in comparison with inhalation of N2O. 2. Fetal or neonatal rats were exposed to an atmosphere containing inhalational anesthetics (70% Xe or N2O) or the control atmosphere (30% O2 and 70% N2) for 6 h. After the exposure, isolated growth cone particles (IGCs) were prepared from their forebrains using a subcellular fractionation method. Protein composition, Ca2+-dependent protein phosphorylation, protein kinase C (PKC) activity, and degradation of PKC in the IGCs were compared among three groups. 3. No apparent change of protein composition in IGCs was observed by electrophoresis. Ca2+dependent phosphorylation of GAP-43 and MARCKS protein, and PKC activity in IGCs significantly decreased after exposure to N20. The degradation of PKC increased significantly after inhalation of N2O. 4. The authors concluded that Xe dose not change the above biochemical characteristic of the growth cones, suggesting that Xe is free from the teratogenic effect on the neuronal network formation and that Xe is a safe anesthetics for the perinatal neuronal development.

Interaction of Epstein-Barr virus nuclear antigen leader protein (EBNA-LP) with HS1-associated protein X-1: implication of cytoplasmic function of EBNA-LP

Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) consists of W1W2 repeats and a unique C-terminal Y1Y2 domain and has been suggested to play an important role in EBV-induced transformation. To identify the cellular factors interacting with EBNA-LP, we performed a yeast two-hybrid screen, using EBNA-LP cDNA containing four W1W2 repeats as bait and an EBV-transformed human peripheral blood lymphocyte cDNA library as the source of cellular genes. Our results were as follows. (i) All three cDNAs in positive yeast colonies were found to encode the same cellular protein, HS1-associated protein X-1 (HAX-1), which is localized mainly in the cytoplasm and has been suggested to be involved in the regulation of B-cell signal transduction and apoptosis. (ii) Mutational analysis of EBNA-LP revealed that the association with HAX-1 is mediated by the W1W2 repeat domain. (iii) A purified chimeric protein consisting of glutathione S-transferase fused to EBNA-LP specifically formed complexes with HAX-1 transiently expressed in COS-7 cells. (iv) When EBNA-LP and HAX-1 were coexpressed in COS-7 cells, EBNA-LP was specifically coimmunoprecipitated with HAX-1. (v) Careful cell fractionation experiments of an EBV-infected lymphoblastoid cell line revealed that EBNA-LP is localized in the cytoplasm as well as in the nucleus. (vi) When EBNA-LP containing four W1W2 repeats was expressed in COS-7 cells, EBNA-LP was detected mainly in the nucleus by immunofluorescence assay. Interestingly, when EBNA-LP containing a single W1W2 repeat was expressed in COS-7 cells, EBNA-LP was localized predominantly in the cytoplasm and was colocalized with HAX-1. These results indicate that EBNA-LP is in fact present and may have a significant function in the cytoplasm, possibly by interacting with and affecting the function of HAX-1.

E-73, an acetoxyl analogue of cycloheximide, blocks the tumor necrosis factor-induced NF-kappaB signaling pathway

Proinflammatory cytokines such as tumor necrosis factor (TNF) and interleukin (IL)-1 activate the NF-kappaB signaling pathway which induces the expression of a variety of genes such as the encoding intercellular adhesion molecule (ICAM)-1. We have found that E-73, an acetoxyl analogue of cycloheximide, specifically blocks TNF-induced ICAM-1 expression even at concentrations unable to affect protein synthesis. By contrast, cycloheximide inhibited both TNF- and IL-1-induced ICAM-1 expression primarily due to the blockage of protein synthesis. The nuclear translocation of NF-kappaB as well as the IkappaB degradation induced by TNF, but not by IL-1, was significantly prevented by E-73. These observations suggest that E-73 blocks the TNF-induced NF-kappaB signaling pathway upstream of IkappaB degradation.

Chemical assay of iron in ovarian cysts: a new diagnostic method to evaluate endometriotic cysts

CA-125 is abundantly secreted from ovarian endometriotic cysts, but is not specific to endometriosis. In order to develop a new, more specific diagnostic marker for endometriosis, the iron concentrations in various ovarian cysts were assayed. The ovarian cysts were punctured and the contents aspirated laparoscopically, laparotomically, or transvaginally. The iron concentration in the ovarian cystic fluid was assayed using a spectrophotometer after protein precipitations and chromogen treatment. The iron concentrations in ovarian cysts were 69.5+/-10.4 micromol/l in serous cystadenomas, 73.5+/-29.3 in mucinous cystadenomas, 65.4+/-12.4 in dermoid cysts, and 92.5+/-18.2 micromol/l in adenocarcinomas. On the other hand, high iron concentrations were demonstrated in endometriotic cysts (1,749.6+/-41.5 micromol/l), a lutein cyst (1,393.8), hemorrhagic corpus luteum (1,957.5) and endometrioid adenocarcinomas (1,860.9+/-157.9 micromol/l). Cytological smear tests of the contents as well as histological examination allowed differential diagnosis between endometriosis and endometrioid adenocarcinoma. In conclusion, assay of the ovarian cystic iron concentration is a useful diagnostic tool for the evaluation of ovarian endometriotic cysts.

Tubelactomicin A, a novel 16-membered lactone antibiotic, from Nocardia sp. I. Taxonomy, production, isolation and biological properties

A novel 16-membered lactone antibiotic named tubelactomicin A was isolated from the culture broth of an actinomycete strain. The producing organism, designated MK703-102F1, was identified as a member of Nocardia. Tubelactomicin A was isolated from the culture broth by Diaion HP20 absorption, ethyl acetate extraction, silica gel and Sephadex LH-20 column chromatographies and centrifugal liquid-liquid partition chromatography (CPC). Tubelactomicin A showed strong activity against acid-fast bacteria including the drug-resistant strains.

Tubelactomicin A, a novel 16-membered lactone antibiotic, from Nocardia sp. II. Structure elucidation

A novel 16-membered lactone antibiotic named tubelactomicin A was isolated from the culture broth of Nocaradia sp. MK703-102F1. The structure of tubelactomicin A was assigned by spectroscopic analysis and the absolute configuration was determined by X-ray crystallographic analysis.

Changes in plasma serotonin concentration and acceleration plethysmograms in patients with Raynaud's phenomenon after long-term treatment with a 5-HT2 receptor antagonist

High blood serotonin concentrations have been reported in patients with Raynaud's phenomenon and a relationship has been suggested. Because of the difficulty in evaluating Raynaud's phenomenon objectively, a possible correlation between blood serotonin concentrations and clinical findings has not yet been evaluated. We measured plasma serotonin concentrations and acceleration plethysmograms (APG) before and one year after administration of a serotonin receptor antagonist. Twenty-seven patients with either collagen disease or diseases associated with Raynaud's phenomenon were given a combined 5-HT2 and serotonin receptor antagonist, sarpogrelate hydrochloride. Plasma serotonin concentrations were determined before and after administration and the APG d/a value was measured as an index of peripheral hemodynamics. These values were compared with the clinical symptoms of the patients. After one year of treatment, the subjective symptoms improved in 59.3% of patients who has Raynaud's phenomenon. The pretreatment plasma serotonin concentrations of the study patients were significantly higher than those of the normal controls, but became significantly decreased following 5-HT2 administration. However, there was no clear-cut relationship with the clinical symptoms. The pre-treatment APG d/a value of the patients was significantly lower than that of the normal controls, although there was no significant difference after administration when analyzed as an entire group or in a subset of patients whose symptoms did not subjectively improve or worsened after one year of treatment. In the subset in whom the subjective symptoms improved, however, the value significantly increased following administration, suggesting an improvement in peripheral hemodynamics. These results suggest the possibility that APG can be used as an objective index of peripheral hemodynamics.

Impaired neural regulation of insulin secretion related to the leptin receptor gene mutation in Wistar fatty rats

The Wistar fatty (WF) rat is a model of obese Type 2 diabetes mellitus (DM). These rats were bred by crossing Zucker fatty (ZF) and Wistar-Kyoto (WKY) rats. A homo-allelic leptin receptor gene mutation has been reported in ZF rats. We report here how these genetic factors contribute to plasma insulin regulation. The fasting plasma insulin levels were higher in WKY and Wistar lean (WL) rats than in Zucker lean (ZL) rats (p<0.05). The levels in WF and ZF rats were higher than in their respective lean littermates, WL and ZL rats (p<0.05). After intragastric glucose load, the plasma insulin increase was reduced upon pretreatment by intracerebroventricular (i. c.v.) methylatropine (an antagonist of the cholinergic receptor) injection in WL rats (p<0.05) but not in WF rats. Plasma glucagon-like peptide-1 (GLP-1) response to intragastric glucose load was not affected by methylatropine. After selective hepatic-vagotomy, plasma insulin levels increased in wild-type ZL rats (p<0.05). This increase was not observed in heterozygote ZL rats. Surprisingly, this response of plasma insulin was not shown in wild-type WL and WKY rats. ZF and WF rats did show a prominent decrease in insulin response (p<0.05). These results indicate that the genetic factor in ZF rats is associated with impaired vagal nerve-mediated control of insulin secretion. The genetic factor in WKY rats may diminish sensitivity to the vagal information of insulin release and contribute to insulin resistance. Therefore, we conclude that the presence of both genetic factors in a homo-allelic state is important to the development of DM in WF rats.

nm23 in the primary and metastatic sites of gastric carcinoma. Relation to AFP-producing carcinoma

Tumor metastasis is the major cause of treatment failure and death in cancer patients. The present study was designed to extrapolate the association of nm23 expression with acquisition of metastatic potential of gastric carcinoma with special reference to the alpha-fetoprotein-producing gastric carcinoma (APGC). The primary tumor with surrounding normal mucosa and metastatic lymph nodes of 30 patients with APGC and 29 randomly selected matched controls of non-AFP gastric carcinoma (NAGC) were immunostained for nm23 and an image analyzer system was used for quantitative evaluation. Overexpression of nm23 was noted in 71% (42/59) of the primary tumors and 18% (10/55) of the metastatic tumors and there was no difference between the APGC and NAGC groups. The overexpression of nm23 in the primary tumors correlated with tumor invasion, metastasis and progression in all cases and similar results were obtained in the APGC and NAGC groups except for the tumor stage which was insignificant in the APGC group. The patient survival was adversely affected by the overexpression of nm23 in the primary sites and downregulation in the metastatic sites in all cases but lost their significance in the multivariate analysis. However, nm23 status did not affect patient survival in the APGC group.

Fentanyl improves analgesia but prolongs the onset of axillary brachial plexus block by peripheral mechanism

We evaluated the effects of fentanyl added to lidocaine for axillary brachial plexus block in 66 adult patients scheduled for elective hand and forearm surgery. In this double-blinded study, all patients received 40 mL of 1.5% lidocaine with 1:200,000 epinephrine, injected into the brachial plexus sheath using the axillary perivascular technique, and they were randomized into three groups. Group 1 was given lidocaine containing 2 mL of normal saline plus 2 mL of normal saline IV. Patients in Group 2 received lidocaine containing 100 microg fentanyl plus 2 mL of normal saline IV. Group 3 patients received lidocaine containing 2 mL of normal saline plus 100 microg fentanyl IV. Sensory and motor blockade were evaluated by using a pinprick technique and by measuring the gripping force, respectively. The success rate of sensory blockade for radial and musculocutaneous nerves and the duration of the sensory blockade significantly increased in Group 2 (323 +/- 96 min) as compared with Group 1 (250 +/- 79 min). However, onset time of analgesia was prolonged in every nerve distribution by adding fentanyl to brachial plexus block. IV fentanyl had no effect on the success rate, onset, or duration of blockade. We conclude that the addition of fentanyl to lidocaine causes an improved success rate of sensory blockade but a delayed onset of analgesia, although this may be accounted for by the decreased pH caused by the fentanyl.

IMPLICATIONS

It is still unclear whether the addition of a peripheral opioid is useful for nerve blockade in humans. Peripheral application of fentanyl to lidocaine for axillary brachial plexus blockade in this study provided an improved success rate of sensory blockade and prolonged duration.

Insulin activates p38 mitogen-activated protein (MAP) kinase via a MAP kinase kinase (MKK) 3/MKK 6 pathway in vascular smooth muscle cells

BACKGROUND

Induction of stress-activated mitogen-activated protein (MAP) kinases such as p38 could be important for the development of cardiovascular diseases since p38 MAP kinase activation stimulates apoptosis, cell growth, prostanoid formation and other cellular dysfunctions when induced by oxidants, hyperosmolarity, or pro-inflammatory cytokines. On the other hand, insulin resistance is one of the most important factors promoting atherogenesis, including cardiovascular diseases, but it is not clear how these different factors transmit their signals intracellularly at the cytosolic and nuclear levels. In this study, we investigated the effect of insulin on p38 mitogen-activated protein (MAP) kinase activation in cultured rat vascular smooth muscle cells (VSMC).

MATERIALS AND METHODS

VSMC were obtained from the aortas of male Wistar rats by the media explant technique. After being stimulated by insulin with SB-203580, PD-98059, or GF109203X, the cells were solubilized and the expressions of MAP kinases, MAP kinase kinases and p70 S6 kinase were examined by immunoblot analysis. The amount of DNA synthesis was measured by [3H]thymidine incorporation.

RESULTS

Insulin activated p38 MAP kinase phosphorylation in a dose-dependent manner, and the phosphorylation was specifically inhibited by SB-203580, a p38 MAP kinase-specific inhibitor, but not by PD-98059, a specific inhibitor of upstream kinase (MEK), of extracellular signal-regulated kinase (ERK), or GF209203X, a protein kinase C-specific inhibitor. Insulin also activated MAP kinase kinase (MKK) 3/MKK 6 phosphorylation, the upstream kinase of p38 MAP kinase, but neither stress-activated protein kinase (SAPK)/ERK kinase (SEK1/MKK4) nor SAPK/c-jun NH2-terminal protein kinase. Surprisingly, phosphorylation of p70 S6 kinase and an increase of DNA synthesis by insulin were suppressed dose dependently by SB-203580.

CONCLUSION

These results have established that insulin activates the p38 MAP kinase cascade via an MKK 3/6 pathway in rat VSMC, independently of a MEK-ERK cascade, and partly regulates cell growth.

The relationship between angioblastoma (Nakagawa) and tufted angioma: report of four cases with angioblastoma and a literature-based comparison of the two conditions

We report four recent cases of angioblastoma (Nakagawa). Histopathologic examinations of all cases revealed dispersed islets of clear marginal lobules of varying sizes in the dermis. Neoplastic endothelioid cells with moderate atypia and enlarged capillaries containing erythrocytes were found in the conglomerates. Recently, the features of this disease have been compared to the tufted angioma that has been reported in Europe and the U.S. Our evaluation suggests that these two diseases are very likely the same. We suggest that this disease should be called "angioblastoma" in agreement with the first report of this disease by Nakagawa.

Japanese paediatricians' judgement of the appropriateness of bathing for children with colds

OBJECTIVES

This study investigated the decisions which Japanese paediatricians make regarding bathing a child with a common cold.

METHODS

A total of 486 printed questionnaires were mailed to paediatricians systematically sampled from the list of members of the Japanese Pediatric Association. The questionnaire included two main questions. (i) Do you permit a 2- to 4-year-old child with a common cold to take a bath? (ii) If the answer to (i) was 'yes', what conditions should limit bathing of such children, and if the answer was 'no', why do you forbid bathing? In addition, the questionnaire included the age and sex of the practitioner, and the type and location of the practice.

RESULTS

A total of 269 paediatricians returned questionnaires (response rate 55%); of these, 88% permitted a child with a cold to take a bath. Of these paediatricians, 5% permitted it without any conditions. The main conditions for taking a bath indicated by these paediatricians were 'no fever' (72%), 'not in a severe physical condition' (27%) and 'after 2 or 3 days from onset' (19%). Thirty-nine paediatricians indicated a specific body temperature at which bathing was appropriate. One-third of these paediatricians did not permit bathing at body temperatures above 38 degrees C. Of the 31 paediatricians (12%) who answered that a child with a cold should not take a bath, 61% were concerned for the physical well-being of the child. However, 29% provided no supporting evidence.

CONCLUSIONS

Japanese paediatricians' judgements concerning bathing of a child with a cold are related to the effects of bathing on physical condition. Bathing immersed up to the neck does not always affect physical conditions. It is necessary to establish appropriate parental and patient education concerning bathing of children with colds.

A case of ileocolic intussusception from renal cell carcinoma

We report a case of ileal metastasis of renal cell carcinoma (RCC) in a 58-year-old male. The patient had a history of radical nephrectomy for a right RCC, and 2 years later underwent bilateral partial pneumonectomy for metastatic disease of the lung. A period of 1 year after the partial pneumonectomy, he developed bloody stools. Colonoscopy revealed an ileocolic intussusception caused by a polypoid tumor in the ileum, and the tumor was observed to be protruding into the ascending colon. The histological features of the tumor biopsy specimen confirmed the diagnosis of metastatic RCC. Metastasis of RCC in the small bowel is a rare disease clinically. To our knowledge, this is the first reported case with ileal metastasis of RCC, which has been definitively diagnosed by colonoscopy.

Fentanyl improves analgesia but prolongs the onset of axillary brachial plexus block by peripheral mechanism

We evaluated the effects of fentanyl added to lidocaine for axillary brachial plexus block in 66 adult patients scheduled for elective hand and forearm surgery. In this double-blinded study, all patients received 40 mL of 1.5% lidocaine with 1:200,000 epinephrine, injected into the brachial plexus sheath using the axillary perivascular technique, and they were randomized into three groups. Group 1 was given lidocaine containing 2 mL of normal saline plus 2 mL of normal saline IV. Patients in Group 2 received lidocaine containing 100 microg fentanyl plus 2 mL of normal saline IV. Group 3 patients received lidocaine containing 2 mL of normal saline plus 100 microg fentanyl IV. Sensory and motor blockade were evaluated by using a pinprick technique and by measuring the gripping force, respectively. The success rate of sensory blockade for radial and musculocutaneous nerves and the duration of the sensory blockade significantly increased in Group 2 (323 +/- 96 min) as compared with Group 1 (250 +/- 79 min). However, onset time of analgesia was prolonged in every nerve distribution by adding fentanyl to brachial plexus block. IV fentanyl had no effect on the success rate, onset, or duration of blockade. We conclude that the addition of fentanyl to lidocaine causes an improved success rate of sensory blockade but a delayed onset of analgesia, although this may be accounted for by the decreased pH caused by the fentanyl.

IMPLICATIONS

It is still unclear whether the addition of a peripheral opioid is useful for nerve blockade in humans. Peripheral application of fentanyl to lidocaine for axillary brachial plexus blockade in this study provided an improved success rate of sensory blockade and prolonged duration.

[Ocular counter-rolling after prolonged alteration in the direction of gravity]

To investigate the dynamics of otolith and oculomotor function, we subjected volunteers to a lateral body tilt for a period of two hours and analyzed ocular counter-rolling. Six healthy adult volunteers were roll-tilted along the naso-occipital axis at a speed of 0 degree/sec. from the 0 degree earth vertical position to the 90 degrees lateral tilt position. After two hours, the volunteers were returned to the 0 degree earth vertical position. Ocular counter-rolling was recorded using an infrared CCD camera. The video recordings were made in the dark while the volunteers had their eyes open. Recordings were obtained (1) as the volunteers was moved from the 0 degree earth vertical position to the 90 degrees lateral position, (2) 5 minutes after reaching the lateral position, (3) during the roll-back from the 90 degrees lateral position to the 0 degree upright position, two hours after the lateral tilt loading, and (4) 5 minutes after reaching the final upright position. The occurrence of ocular counter-rolling between the 0 degree upright position and the 30 degrees tilt position was confirmed during both roll movements from 0 degree to 90 degrees and from 90 degrees to 0 degree. The counter-rolling was most noticeable between the 0 degree and the 30 degrees positions. No differences in ocular counter-rolling during the roll-tilt and the roll-back situations were observed. These results indicate that the two-hour lateral tilt position did not produce any functional changes in the hair cells and/or the otolith-oculomotor system. All of the subjects exhibited ocular counter-counter-rolling during the initial stage of their roll-back to a normal upright position. This phenomenon might result from the additional bending of the hairs by inertia during the initiation of the backward roll motion.

Sustained activation of Ras/Raf/mitogen-activated protein kinase cascade by the tumor suppressor p53

The p53 tumor suppressor gene can inhibit proliferation transiently, induce permanent cell-cycle arrest/senescence, or cause apoptosis depending on the cellular context. The mitogen-activated protein kinase (MAPK) cascade is known to play a crucial role in cell proliferation and differentiation. Moreover, the duration and intensity of MAPK activation can profoundly influence the biological response observed. We demonstrated that a sustained activation of MAPK cascade could be induced by wild-type p53 expression but not by p21(Waf1/Cip1). Furthermore, exposure of normal cells to DNA-damaging agents induced MAPK activation in a p53-dependent manner. Tumor-derived p53 mutants defective in DNA binding failed to activate MAPK, implying that p53 transcriptional activity is essential for this function. Finally, activation of MAPK by p53 was inhibited by expression of dominant-negative Ras (N17Ras) and Raf1 mutants, indicating that MAPK activation by p53 is mediated at a level upstream of Ras. All of these findings establish a biochemical link between p53 signaling and the Ras/Raf/MAPK cascade.

Stress vulnerability and climacteric symptoms: life events, coping behavior, and severity of symptoms

To explore a possible association between climacteric symptoms and ways of coping with stress, a comparative study was conducted among 19 menopausal women who sought treatment for climacteric symptoms (the study group) and 44 healthy menopausal women (the control group). Life stress was assessed using a life event method in which factor analysis extracted four ways that women cope with stress: avoidance-oriented coping, consultation-oriented coping, aggression-expression coping, and problem-solving coping. The study group had a higher symptom score and was more prone to avoidance-oriented coping than the control group despite experiencing the same number of undesirable life events. The severity of climacteric symptoms correlated positively with the number of undesirable life events and the degree of avoidance-oriented coping and correlated negatively with the degree of aggression- expression coping for the study group. These results suggest that vulnerability to stress contributes to worsening climacteric symptoms caused by stress.

A novel mutation of the ceruloplasmin gene in a patient with heteroallelic ceruloplasmin gene mutation (HypoCPGM)

We found a novel missense mutation in the ceruloplasmin (Cp) gene in a patient with the heteroallelic Cp gene mutation (HypoCPGM). The patient was a 72-year-old woman who came to our hospital with a 1-year history of postural tremor of the hands. The diagnosis was made based on serum Cp and copper readings which were about half the normal levels, as well as MRI tests of her brain which showed characteristics for hereditary ceruloplasmin deficiency (HCD), known to be caused by the homoallelic Cp gene mutation. Polymerase chain reaction (PCR)-direct sequencing analysis of the Cp gene of the patient revealed a novel point mutation, A to T, at nucleotide position 82 in Exon 1. This mutation changes the Ile28 codon (ATT) to a Phe codon (TTT) (missense mutation). PCR-restriction analysis with restriction enzyme Tsp EI for the mutation revealed that both the patient and her son were heterozygotes for the mutation.

Localization and targeting of SCG10 to the trans-Golgi apparatus and growth cone vesicles

SCG10 is a membrane-associated, microtubule-destabilizing protein of neuronal growth cones. Using immunoelectron microscopy, we show that in the developing cortex of mice, SCG10 is specifically localized to the trans face Golgi complex and apparently associated with vesicular structures in putative growth cones. Consistent with this, subcellular fractionation of rat forebrain extracts demonstrates that the protein is enriched in the fractions containing the Golgi apparatus and growth cone particles. In isolated growth cone particles, SCG10 was found to be particularly concentrated in the growth cone vesicle fraction. To evaluate the molecular determinants of the specific targeting of SCG10 to growth cones, we have transfected PC12 cells and primary neurons in culture with mutant and fusion cDNA constructs. Deletion of the amino-terminal domain or mutations within this domain that prevented palmitoylation at cysteines 22 and 24 abolished Golgi localization as well as growth cone targeting, suggesting that palmitoylation of the amino-terminal domain is a necessary signal for Golgi sorting and possibly transport of SCG10 to growth cones. Fusion proteins consisting of the amino-terminal domain of SCG10 and the cytosolic proteins stathmin or glutathione-S-transferase colocalized with a Golgi marker, alpha-mannosidase II, and accumulated in growth cones of both axons and dendrites. These results reveal a novel axonal/dendritic growth cone targeting sequence that involves palmitoylation.