Adjuvant chemotherapy for transplanted hepatocellular carcinoma patients: impact on survival or HCV recurrence timing

INTRODUCTION

Hepatocellular carcinoma (HCC) is one of the most common tumors worldwide. In the Western world the current epidemic of cirrhosis due to the hepatitis C virus (HCV) is increasing the number of new cases. Liver transplantation (OLTx) represents a radical treatment for HCC and the underlying cirrhosis. Whether adjuvant chemotherapy is indicated in the postoperative period to prevent recurrence is controversial.

MATERIAL AND PATIENTS

Forty-eight HCC patients underwent liver transplantation during 11 years, including 21 who were chemo-treated (CT) patients. Thirty-one patients (65%) had post-necrotic virus-C cirrhosis (PNC-C). Twenty-one cases (44%) were p-TNM stages III-IV, and 15 cases (31%) incidental HCC detected in the explanted liver. Seven HCV patients (15%) received chemotherapy (before 1998).

RESULTS

One-, 3-, and 5-year overall survival rates were 100%, 85%, 79% (CT group), and 89%, 71%, 71% (no CT group), respectively. The HCV recurrence-free survival rates at 3, 6, and 12 months were 29%, 14%, 0% for the CT group, versus 76%, 38%, 25% for the no CT group (P =.005).

CONCLUSIONS

Discontinuation of HCV-HCC patients by chemotherapeutic adjuvant protocols after transplantation appears rational due to the early hepatitis C recurrence confirmed in our series. Moreover, few studies have demonstrated that CT prolongs survival of HCC transplanted patients. New pharmacological approaches are necessary to solve these questions.

First Occurrence of Downy Mildew on Boxleaf Veronica Caused by Peronospora grisea in Italy

Boxleaf veronica (Hebe buxifolia (Benth.) Cockayne & Allan), native to New Zealand, is an annual or perennial shrub widely cultivated in Mediterranean zones. During late spring 2003, after seasonably wet and cool weather, a downy mildew epidemic occurred on potted, overhead irrigated, 1-year-old seedlings at a commercial nursery in eastern Sicily (southern Italy). Infections affected boxleaf veronica at first, but spread to variegated boxleaf (H. buxifolia cv. variegata). Initial symptoms on the upper side of leaves were small, gray brown patches that gradually spread, eventually resulting in necrosis in the center of infected areas. At that point, brown patches were evident on both sides of the leaves. Lesions on the lower leaf surface became covered with a fairly dense, pale gray-to-brown layer of conidia and conidiophores. As the disease progressed, these spots coalesced into large and conspicuous brown lesions. The youngest, most succulent shoots withered and died. The large brown lesions on the leaves were disfiguring and affected 95 to 100% of plants in the nursery. All diseased nursery stock had to be discarded. Oospores were not observed in leaf tissues. The fungus recovered from leaves with abundant gray brown sporulation was identified as Peronospora grisea (Unger) Unger. Microscopic observations revealed conidiophores that branched dichotomously five to seven times with branch ends 6 to 10 × 2 to 3 μm, slightly curved, and tapered to a blunt apex. Hyaline conidia were ellipsoid, brownish when mature, and measured 23 to 27 × 15 to 18 μm (mean = 25.2 × 17.1 μm), falling within the range of those reported for P. grisea (1). Pathogenicity was confirmed by inoculating 10 1-yr-old seedlings (10 cm tall) by gently pressing infected leaves with abundant sporulation onto healthy leaves and maintaining inoculated plants in a humid chamber at 21°C. An equal number of noninoculated plants served as controls. After 9 to 11 days, symptoms similar to those originally observed developed onto inoculated plants, and after 12 to 15 days, grayish mildew grew on leaves. Microscopic examination of the developing mycelium confirmed that leaves were infected with P. grisea. Uninoculated control plants did not develop any symptoms. The disease was also confirmed in this way on variegated boxleaf veronica (H. buxifolia cv. variegata). Downy mildew of Hebe spp. has been recorded in New Zealand, Britain, France, Germany, and more recently, West Sussex (2). Heavy rainfall during the spring of 2003 in eastern Sicily could have favored disease development. To our knowledge, this is the first report of downy mildew of boxleaf veronica and variegated boxleaf veronica caused by P. grisea in Italy. References: (1) S. M. Francis and A. M. Berrie. Peronospora grisea. No. 766 in: Descriptions of pathogenic fungi and bacteria. CMI, Kew, Surrey, UK. 1983. (2) J. M. Whipps and C. A. Linfield. Plant Pathol. 36:216, 1987.

First Report of Southern Blight Caused by Sclerotium rolfsii on Laurustinus

Laurustinus (Viburnum tinus L.), native to the Mediterranean Region, is an evergreen shrub commonly used as a specimen shrub or small tree or used in border plantings. During August 2003, a blight occurred on 2-year-old-plants of laurustinus growing in pots in a nursery in eastern Sicily (Italy). Disease incidence ranged from 2 to 5% across the field. Symptoms included 3 to 4 cm long lesions and the development of white mycelial strands and brown, 1.0 to 1.8 mm, nearly spherical sclerotia on the crown of plants at the soil line that are typical of Sclerotium rolfsii Sacc. The foliage of infected plants wilted, followed by a sudden collapse of the plant. The fungus was consistently isolated on acidified potato dextrose agar (PDA) (pH 4.5) by plating symptomatic tissues that were surface disinfested (1.2% NaOCl) for 1 min. and rinsed in sterile water. Pathogenicity tests were performed by sprinkling 50 sclerotia, obtained from infected oat kernels (2), on the soil surface around the collar of each of 10 healthy, potted 1-year-old plants of laurustinus. Five of the plants were previously wounded on the crown 1.5 cm above or below the soil line with a sterile needle. Five noninoculated plants served as controls. All plants were maintained at 25 ± 2°C and enclosed for 72 hr in polyethylene bags (90 to 95% relative humidity). Blight symptoms similar to those seen in nursery were observed on inoculated plants 20 to 25 days after inoculation, while no symptoms developed on control plants. Koch's postulates were fulfilled by reisolation of the fungus on acidified PDA from all infected laurustinus plants. S. rolfsii was previously recorded on Prague viburnum (Viburnum × pragense L.) as the causal agent of southern blight (1). To our knowledge, this is the first report of southern blight caused by S. rolfsii on laurustinus. References: (1) A. Hagan. Southern blight on flowers, shrubs, and trees. On-line publication ANR-1157. Alabama A & M, and Auburn University ( www.aces.edu/dept/extcomm/publications/html ). (2) R. Rodriguez-Kabana et al. Plant Dis. Rep. 59:5, 1975.

First Report of Basal Stem Rot of Golden Barrel Cactus Caused by Fusarium oxysporum f. sp. opuntiarum in Italy

Golden barrel cactus (Echinocactus grusonii Hildm.) is the most common landscape cactus in southern Italy. During 2000, 2001, and 2002, a basal stem rot of golden barrel cactus was observed in several plastichouses located in eastern Sicily with disease levels of nearly 100% on young plants (up to 15 cm in diameter). On the basal crown area, the plants showed pale brown or yellow-orange, sunken lesions bordered by a reddish orange strip up to 1 mm wide. A water-soaked rot or white mycelium at the soil line was also observed. Thirty pieces (0.5 to 1 cm) from the edge of symptomatic tissues were surface disinfected for 2 min in 0.8% (wt/vol) NaOCl, washed with sterile distilled water (SDW), and placed on potato dextrose agar (PDA). In addition, 20 pieces of affected tissue were ground in 400 μl of SDW (1:3, wt/wt), and the resulting suspensions were streaked by loops on PDA supplemented with 1.1 μl/ml of lactic acid (pH 4.4). A Fusarium sp. was consistently isolated from affected tissue pieces and streaks. Koch's postulates were performed at 25°C by inoculating 24 golden barrel cactus plants in 12-cm-diameter pots (12 plants previously sterile needle wounded) with 10 ml per plant of three suspensions (10⁶ CFU/ml) of three isolates sprayed onto the basal stem. One milliliter per ten g of soil of each suspension was also added in the crown portion of golden barrel cacti. Twelve control cacti (six wounded) were sprayed only with SDW. Further pathogenicity tests were carried out on Thanksgiving cactus (Schlumbergera truncata (Haw.) Moran), devil's tongue barrel cactus (Ferocactus latispinus (Haw.) Britton & Rose), peruvian old man cactus (Espostoa lanata (Kunth) Britton & Rose), and Parodia spp. by inoculating eight plants for each host (four wounded) by placing 9-day-old 6-mm mycelial plugs at the base of the healthy cacti. An equal number of plants (four wounded) was inoculated only with a PDA plug. All cacti were maintained in polyethylene bags (90 to 95% for 72 hr) at 25°C. After 12 to 15 days, all wounded inoculated golden barrel, devil's tongue barrel, and peruvian old man cacti exhibited similar symptoms observed in the plastichouses. Typical symptoms were visible also in nonwounded and inoculated cacti 15 days later. Yellow-orange, tan, sunken, and roughly circular lesions were observed on the wounded and inoculated Thanksgiving and Parodia sp. cacti. Control plants were symptomless. The causal fungus was always reisolated from infected cacti. On the basis of 3-septate macroconidia (27 to 35 μm long × 3 to 4 μm wide [average 31.45 × 3.18 μm]), microconidia aseptate, single or double chlamydospores, and monophialide conidiophores observed on carnation leaf agar, and considering the susceptibility of all other inoculated hosts, the fungus was identified as F. oxysporum Schlechtend. f. sp. opuntiarum (Speg.) (1). To our knowledge, this is the first report of basal stem rot of golden barrel cactus in Italy. Reference: (1) W. Gerlach. Phytopathol. Z. 74, 197, 1972.

Liver transplantation for the management of hepatoblastoma

INTRODUCTION

Hepatoblastoma (HEP) is the most frequent liver malignancy occurring in childhood. Surgical resection currently represents the gold standard for treatment. In patients with initially unresectable tumors, chemotherapy may induce remarkable reductions in size. In nonresponder patients, liver transplantation (OLTx) may offer a chance of cure.

MATERIALS AND METHODS

From 1990 to 2003, a total of 400 OLTx (31 pediatric transplants) have been performed at Padua University. Seven patients (4 males and 3 females) underwent OLTx for hepatoblastoma. All patients presented with bilobar liver involvement and had received chemotherapy according to the SIOPEL-1. In all patients preoperative staging was negative for extrahepatic involvement.

RESULTS

The mean age of the pts was 8.2 years (range 6.4 months to 34 years). Mean follow-up after OLTx was 41.4 months (median 36, range 3 to 108 months). Actuarial patient survival rates after OLTx for hepatoblastoma are 83.3%, 83.3%, and 56% at 1, 3, and 5 years, respectively. Five of seven subjects with HEP are alive after transplant at 3, 12, 36, 65, and 108 months. Two patients died owing to recurrent disease after 6 and 60 months, respectively, from transplantation. Another subject, primarily treated with surgical resection, shows HEP recurrence at 40 months after OLTx. The remaining 4 patients are alive and well at a mean follow-up of 28 months (median 24, range 3 to 65 months).

CONCLUSIONS

Liver transplantation may represent a valid therapeutic option for patients with unresectable HEP, but it is contraindicated in cases of recurrence following previous resection surgery. Neo-adjuvant chemotherapy is of paramount importance to obtain good long-term results.

First Report of Leaf Spot and Blight Caused by Botrytis cinerea on Pygmy Date Palm in Italy

Pygmy date palm (Phoenix roebelenii O'Brien), native to Laos and southeast Asia, is one of the most commonly cultivated date palms both indoors and out. In early April 2003, a new and widespread leaf disease was detected on 2- to 3-feet high, potted, pygmy date palms growing in open fields or shade-houses in four commercial nurseries of the eastern Sicily Region of southern Italy. Initial symptoms on infected plants were small, chlorotic spots on blades and edges of leaflets. As spots enlarged, yellow or reddish-brown margins and brown or gray, wrinkled, sunken centers developed. Sometimes, spots or lesions coalesced to cause blight of young expanding leaves or death of apical buds. Botrytis cinerea Pers.:Fr was recovered consistently from sections of infected tissues (disinfected for 1 min in 1% NaOCl and rinsed in sterile water) plated on malt extract agar. On potato dextrose agar (PDA), colonies of B. cinerea were first hyaline, then turned white, and later turned dark gray when spores differentiated. Six- to eight-day-old-cultures developed white sclerotia that turned black after three more days. Conidia in 1-month-old-cultures were hyaline or gray, ovoid, and ranged from 5.2 to 8.8 × 8 to 14 μm (average 6.6 × 9.9 μm). Black microsclerotia were round or irregular in shape and ranged from 0.6 to 2.8 × 0.3 to 2.5 mm (average 1.66 × 0.98 mm) (1). Koch's postulates were performed by spraying potted, 9-month-old pygmy date palms (2 feet high) with a spore suspension (1 × 10⁶ CFU per ml from 15-day-old cultures grown on PDA). Six plants were wounded and inoculated, while six plants were inoculated without wounding. An equal number of noninoculated plants sprayed with sterile water served as controls. All plants were maintained in a humid environment at 20°C. Sunken-leaf and rachis lesions were observed on all wounded and most nonwounded plants within 10 to 14 days after inoculation. Symptoms did not develop on the control plants. Koch's postulates were fulfilled by reisolation of the fungus from affected tissues. A field survey revealed the occasional presence of similar leaf spots on canary island date palms (Phoenix canariensis Hort. ex Chabaud), from which B. cinerea was consistently recovered. The unusually cool and humid weather conditions recorded in Sicily during this disease outbreak were very conducive for occurrence of the B. cinerea infections. Although the disease only occasionally caused death of plants, evidence indicated that B. cinerea reduced commercial value of infected pygmy date palms. B. cinerea was previously recorded in northern Italy on canary island date palm (2) and was recently detected in southern Italy on majesty palm (3). To our knowledge, this is the first report of leaf spot and rachis blight caused by B. cinerea on pygmy date palm. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CAB, Kew, Surrey, England, 1971. (2) A. Garibaldi and S. Rapetti. No. 9 Suppl. Flortecnica, 1987. (3) G. Polizzi. Plant Dis. 86:815, 2002.

First Report of Fusarium Blight on Majesty Palm Caused by Fusarium proliferatum in Italy

During spring 2002, a new disease of majesty palm (Ravenea rivularis Jumelle & H. Perrier) was observed on young, container-grown plants (3 to 4 years old with five to seven expanded leaves) in a nursery in eastern Sicily. Initial symptoms on the youngest, expanded leaves and especially on the unopened, spear leaves were small, reddish-brown necrotic lesions (2 to 4 mm in diameter) with a yellow halo. In high humidity, lesions increased in size and number, coalescing into large, irregular dead areas. These symptoms developed into blights of the youngest, unopened leaves. As a consequence, infected leaves would dieback and only a few plants recovered from these severe infections. On the surviving plants, reddish-brown necrotic lesions appeared on the rachis. From these lesions, 30 pieces of tissue were cut, surface sterilized (30 s in 1.2% wt/vol of NaOCl), washed with sterile water, and plated on potato dextrose agar supplemented with 1.1 μl/ml of lactic acid (stock 88 to 92%) (A-PDA). Conidia and conidiophores were collected directly from the tissue with a flamed needle and placed on A-PDA. Fusarium sp. was consistently isolated from the necrotic tissue, and after 3 days, single hyphal tips were transferred to pure cultures from which were obtained two single, conidial isolates. These fungal isolates were forwarded to the CABI Bioscience U.K. Centre, Bakeham Lane (Egham), Surrey, U.K., where both isolates were identified as Fusarium proliferatum (T. Matsushima) Nirenberg. A morpho-biometrical characterization was performed on carnation leaf agar with a photoperiod of 10 h. Macroconidia were slender, lightly falcate to almost straight, 3- to 5-septate, and ranged from 37 to 53 × 2.5 to 3 μm (average 44.1 × 2.8 μm). Microconidia, clavate or oval with a truncated base, were formed in chains from mono- or polyphialides. Chlamydospores were absent. Eight 2-year-old seedlings (three to five expanded leaves) of majesty palm had the unopened spear leaves needle-wounded and another eight were unwounded. All were sprayed with a conidial suspension (1.5 × 10⁶ CFU/ml). An equal number of noninoculated plants were used as a control. All plants were covered with polyethylene bags and incubated in a greenhouse at 25 ± 2°C for 72 h. All wounded majesty palms showed brown areas on unopened spear leaves. When natural injures were present, reddish leaf spots appeared as early as 4 days after inoculation. Macroscopic observations revealed the presence of white mycelium on the necrotic areas and reddish spots. Koch's postulates were satisfied by reisolation of the fungus on A-PDA from artificially infected tissues. On the basis of 3 months of field observations in Sicily, spread of Fusarium blight on majesty palm was always greater when plants were injured on the tender and unopened leaves by volcanic cinders from Mt. Etna, which caused bruises on young leaves. The disease does not represent a major threat to nurseries, but it could cause loss in the cultivation of the majesty palm. F. proliferatum was previously recorded in Saudi Arabia as the causal agent of wilt and dieback of date palm (1). To our knowledge, this is the first report of F. proliferatum on palms in Italy and the first outbreak of the disease on majesty palm. Reference: (1)M. Y. Abdalla et al. Plant Dis. 84:321, 2000.

Extreme marginal donor: severe hypothermia as a rare preservation condition for explantable organs--a case report

The progressive increase in patients with end stage liver disease has lengthend the waiting- list for liver transplantation. Unfortunately this has not been followed by a suitable increase in the number of donors. The expanding "donor pool" has required use of "marginal" donors (ICU stay > 10 days, sepsi; steatosis > 30-40%, hypernatremia > 155 mmol/L, inotropic drugs). We report the case of a skier who remained for more than 1 hour in cardio-respiratory arrest under the snow; the 49-year-old women was extracted from the snow after 1 hour and 12 minutes and found to be asystolic, fixed pupils and deep hypothermia (27.2 degrees C). After cardiopulmonary resuscitation, partial cardio-respiratory activity was re-established. In the ICU severe hypothermia (26.7 degrees C) was treated with extracorporeal circulation until a re-establishment of satisfactory cardio-circulatory conditions was obtained. Unfortunately cerebral anoxic cerebral death was established and multiorgan procurement performed 3 days later. After liver transplantation into a 59 year-old patient with PNC-C was performed. The course was uneventful and the patient was discharged on the 19th postoperative day.

CONCLUSIONS

Organ procurement from donors involved in accidental traumatic events with cardio-respiratory arrest and hypothermia, is similar to the non-heart-beating donor (NHBD) condition. Correct cardiopulmonary resuscitation and the use of extracorporeal circulation for gradual restoration of body temperature are necessary for optimal organ perfusion. In the present case the anoxic insult induced by the cessation of the cardio-respiratory function, was probably mitigated (if not even annulled) by the hypothermia.

The puzzle-feeder as feeding enrichment for common marmosets (Callithrix jacchus): a pilot study

The use of a puzzle-feeder, as feeding enrichment, was investigated in three families of captive common marmosets (Callithrix jacchus). The study was carried out as a simultaneous choice test between two cages: one contained the puzzle-feeder, the other contained the usual food dishes, but otherwise both were arranged similarly. The monkeys were allowed to choose whether to feed from the usual dishes, or from the puzzle-feeder which required more effort. They were observed for two sessions in which they were differently motivated to feed. The enriched cage was always visited first, the marmosets managed to extract food from the puzzle-feeder, and spent more time eating from the puzzle-feeder when less hungry. These data contribute to a wider understanding on the use, and the effects, of feeding enrichments with different captive non-human primates.

Papnet-assisted cytological diagnosis intensifies the already marked variability among cytological laboratories

OBJECTIVE

The main objective was to assess the sensitivity, specificity and reliability of PAPNET-assisted diagnosis in comparison with conventional screening.

SETTING

Seven Italian and one English University or Research Institutes, and a random sample of an other 20 Italian Laboratories of the Italian National Health Service (INHS) provided the cervical smears.

METHODS

During the training phase every center examined in rotation four sets of slides for a total of 300 representative slides. Afterwards, 900 "positive" slides were added to the 3,100 slides which were collected consecutively without any selection or exclusion. The eight main centers were divided into four couples and each couple of centers examined 775 slides with the PAPNET system, "blindly" to the original diagnosis. An expert cytopathologist (M.A.) of the National Institute of Health (NIH) reassessed 40% of the slides with an original negative diagnosis to evaluate the false negative rate. Two expert NIH cytopathologists (M.A., G.M.) re-examined all slides where a disagreement had been observed between the original and one or both of the study diagnoses. The main analyses concerned the following three main categories: WNL and unsatisfactory for evaluation; ASCUS, AGUS and LSIL; HSIL and carcinoma. A special algorithm was devised to define the reference diagnosis for sensitivity and specificity assessment.

RESULTS

Laboratories, even belonging to the same couple, classified as "no review" a very different proportion of slides ranging from 35% to 74%. The index of kappa agreement between the members of couples examining the same sets of slides was low or very low, ranging from 0.30 to 0.03. The sensitivity of the review classification was particularly low in some laboratories. Surprisingly, only a small correlation was observed between the sensitivity of the review classification and the proportion of slides classified as "review". The "tentative" diagnosis on PAPNET tiles of the "review" slides was almost as reliable as the microscopic diagnosis. In the overall performance, there were many significant differences among the eight laboratories. The best laboratory had a sensitivity of 95% and a specificity of 96%. At least three laboratories displayed unacceptably low sensitivity and one a very low specificity.

CONCLUSION

Altogether these results seem to confirm that there are wide differences among cytological laboratories per se, and that these differences are intensified by the use of an instrument like PAPNET. The huge variation in performance may be explained by differences in basic skills and by different training, but it is difficult to understand exactly what could have been done to reduce it.

Barkas effect for antiproton stopping in H2

We report the stopping power of molecular hydrogen for antiprotons of kinetic energy above the maximum (approximately 100 keV) with the purpose of comparing with the proton one. Our result is consistent with a positive difference in antiproton-proton stopping powers above approximately 250 keV and with a maximum difference between the stopping powers of 21%+/-3% at around 600 keV.

First Report of the Prevalence of Benzimidazole-Resistant Isolates in a Population of Cylindrocladium pauciramosum in Italy

Cylindrocladium pauciramosum C.L. Schoch & Crous (teleomorph Calonectria pauciramosa C.L. Schoch & Crous), described as a member of the Cylindrocladium candelabrum Viégas complex (4), was recently reported from Europe (3). In southern Italy, the fungus has caused extensive losses, and chemical control measures are necessary, especially in ornamental nurseries. Several researchers have found benzimidazole fungicides to be effective for control of different species of Cylindrocladium, however, in fungicide trials conducted on myrtle plants infected by C. pauciramosum, benomyl was ineffective (2). Another study showed that mycelial growth of six isolates was completely inhibited by carbendazim at a concentration of 1 μg a.i./ml whereas, concentrations of 10, 100, and 500 μg a.i./ml did not completely inhibit growth of four isolates (1). To examine benzimidazole resistance in C. pauciramosum, 200 single-conidia isolates were tested. These were collected during 1996 and 1997 from several symptomatic hosts in different nurseries located in Sicily and Calabria and identified through morphological characteristics as well as mating-type studies with tester strains. Sensitivity to benomyl was determined by plating mycelial plugs on potato dextrose agar (PDA) amended with benomyl at 1, 10, 100, and 500 μg a.i./ml. For 20 benomyl-resistant isolates, fungal growth was also determined at the same concentrations on carbendazim-amended PDA. Sensitivity was expressed as the minimum inhibitory concentration (MIC) (the lowest fungicide concentration that completely prevented fungal growth). Isolates that did not grow on benzimidazole-amended PDA were classed as sensitive. Isolates were considered resistant to benzimidazole if MIC values were greater than 1 μg a.i./ml. Of the 200 isolates tested, 58% were resistant to benomyl. The benomyl-resistant isolates tested for carbendazim sensitivity were cross-resistant to carbendazim. Most resistant isolates grew in the presence of benomyl at 500 μg a.i./ml. On agar culture, the isolates were either the fast-growing or slow-growing type. The slow-growing phenotype appears to be related to the higher level of resistance (500 μg a.i./ml). On the basis of these data, the use of benzimidazole for the control of this pathogen should be seriously questioned. To our knowledge, this is the first report of the prevalence of benzimidazole resistance in a population of C. pauciramosum. References: (1) G. Polizzi. Inf. Fitopatol. 11:39, 2000. (2) G. Polizzi and A. Azzaro. Petria 6:117, 1996. (3) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (4) C. L. Schoch et al. Mycologia 91:286, 1999.

Vacuolar sorting determinants within a plant storage protein trimer act cumulatively

The mechanism for vacuolar sorting of seed storage proteins is as yet poorly understood and no receptor has been identified to date. The homotrimeric glycoprotein phaseolin, which is the major storage protein of the common bean, requires a transient tetrapeptide at the C-terminus for its vacuolar sorting. A mutated construct without the tetrapeptide is secreted. We show here that coexpression of wild-type phaseolin and the mutated, secreted form in transgenic tobacco results in the formation of mixed trimers and partial vacuolar delivery of the mutated polypeptides and partial secretion of wild-type polypeptides. This indicates that the sorting signal has a cumulative effect within a phaseolin trimer. The result is discussed in the light of the hypothesized mechanisms for vacuolar sorting of seed storage proteins.

First Report of Occurrence of Verticillium Wilt on Some Ornamental Trees in Sicily

In July 1998, a widespread lethal collapse of butterfly tree (Bauhinia purpurea L.), puka tree (Meryta sinclairii Hook.), Indian laurel (Ficus microcarpa L.), golden rain tree (Koelreuteria paniculata Laxm.), and Brazilian pepper tree (Schinus terebinthifolius Raddi.) has been observed in an ornamental growing area near Catania in eastern Sicily. The diseased plants showed yellowing of the leaves and twig dieback. In cross sections of infected trunks, roots, twigs or shoots, characteristic discoloration of xylem vessels was observed, resembling a vascular wilt disease. The disease was chronic with a lingering decline progressing for years. The isolate that was consistently recovered from diseased tissues on PDA was identified as Verticillium dahliae Kleb., based on verticillate conidiophores with phialides and conidia and melanized microsclerotia. Pathogenicity tests were performed on 4- to 6-month-old seedlings of all five ornamental plants by inoculating a suspension of the fungus (1). Symptoms were observed after 5 to 7 months, and V. dahliae was reisolated, confirming Koch's postulates. To our knowledge this is the first report of V. dahliae on Indian laurel, golden rain tree, and Brazilian pepper tree in Italy, and the first report of the disease on butterfly tree and puka tree. Reference: H. A. Melouk and C. E. Horner. Phytopathology 65:767, 1975.

Influence of KDEL on the fate of trimeric or assembly-defective phaseolin: selective use of an alternative route to vacuoles

The tetrapeptide KDEL is commonly found at the C terminus of soluble proteins of the endoplasmic reticulum (ER), and it contributes to their localization by interacting with a receptor that recycles between the Golgi complex and the ER. We investigated the effects of the addition of KDEL to phaseolin, a protein normally delivered from the ER to storage vacuoles via the Golgi complex. We show that KDEL prevents acquisition of trans-Golgi-specific glycan modifications and causes interactions with the chaperone BiP that are distinct from the ones between BiP and defective proteins. KDEL markedly increases the stability of phaseolin, but a small proportion of phaseolin-KDEL slowly reaches the vacuole without undergoing Golgi-mediated glycan modifications, in a process that can be inhibited by brefeldin A but not monensin. Our results indicate that KDEL can operate with high efficiency before proteins can reach the late Golgi cisternae but allows or promotes delivery to vacuoles via an alternative mechanism. However, addition of KDEL does not alter the destiny of an assembly-defective form of phaseolin, suggesting that the plant ER quality control mechanism is dominant over KDEL effects.

Phenotypic and functional characterization of the host immune compartment of chronic myeloid leukaemia patients in complete haematological remission

The role of the host immune compartment in the control of chronic myeloid leukaemia (CML) has been suggested by numerous biological and clinical evidence. In the present study, the phenotypic and functional machinery of both T and cytotoxic lymphocytes was evaluated in a series of CML patients in complete haematological, and frequently also in cytogenetic, remission after treatment with interferon (IFN) alpha or hydroxyurea, and compared with the profile observed in patients at diagnosis and in normal controls. In particular, the lymphocyte subset distribution, the cytotoxic activity and the intracellular production of tumour necrosis factor (TNF)alpha and IFN gamma by CD4(+), CD8(+) and CD56(+) cells were investigated. CML patients in complete haematological remission showed a normalized CD4/CD8 T-cell subset distribution, as well as a restored spontaneous and interleukin 2 (IL-2) induced cytotoxic function compared with the pattern observed at diagnosis. This was associated with a significantly increased proportion of activated CD4(+) lymphocytes (CD25(+)). TNF alpha and IFN gamma production by CD4(+), CD8(+) and CD56(+) lymphocytes was significantly enhanced compared with that of patients at diagnosis. However, the values were lower than those of normal controls. These results indicate that, in contrast to the observations at presentation, CML patients, at the time of the best possible response to treatment, show a normalized T-cell subset distribution associated with an activated CD4 T-cell compartment and a restored cytotoxic activity. In addition, they also show a markedly increased intracellular cytokine production by the lymphoid populations that play an important role in the process of specific tumour recognition. The design of therapeutic strategies aimed at stimulating the host immune compartment finds a further rationale for CML patients responsive to treatment with both IFN alpha and hydroxyurea.

Myeloperoxidase gene expression in non-infant pro-B acute lymphoblastic leukaemia with or without ALL1/AF4 transcript

In this study, we examined myeloperoxidase (MPO) gene expression in a series of 31 non-infant pro-B acute lymphoblastic leukaemia (ALL) patients that included 16 cases with the t(4;11) translocation and/or the resultant ALL1/AF4 chimaeric gene. Sixteen out of 31 cases (51%) were MPO mRNA positive/enzyme negative. MPO mRNA was detected in nine out of 16 (56%) and seven out of 15 (47%) patients with and without the ALL1/AF4 fusion transcript respectively. The comparative study between MPO mRNA positive and negative cases showed statistically significant differences with regard to age and white blood cell (WBC) count, and was 39.5 years vs. 26.3 years (P = 0.016) and 71.4 x 10(9)/l vs. 157.8 x 10(9)/l (P = 0.046) in the MPO mRNA positive and negative groups respectively. The correlation analysis between MPO mRNA expression, age, WBC count and leukaemic relapse according to the presence/absence of the ALL1/AF4 fusion showed that the statistically significant differences observed in the whole group were related mostly to the ALL1/AF4-positive ALL patients. In fact, in this latter group, the mean WBC count and patients' age were 85 +/- 79 x 10(9)/l vs. 289.8 +/- 102 x 10(9)/l (P = 0.0005) and 44.8 +/- 15.3 years vs. 26.7 +/- 13.7 years (P = 0.01) in patients with and without MPO mRNA expression respectively. It appears, therefore, that the assessment of MPO mRNA expression enables a further dissection of leukaemia heterogeneity in apparently homogeneous genetic/immunophenotypic ALL subsets.

Social influence on induced food preference in common marmosets (Callithrix jacchus)

In this paper, we investigate the role of sociality in changing an induced food preference in captive common marmosets (Callithrix jacchus), in the particular case of interactions between animals with contrasting information. After modifying a food preference by making a preferred food unpalatable for pairs of individuals (labelled as conditioned individuals) we recorded food choice under three experimental conditions: pairs interacting (one conditioned pair with one non-conditioned pair); pairs separated (conditioned and non-conditioned pairs by themselves the day after the social condition); control (conditioned and non-conditioned pairs alone). The main results was that only the conditioned individuals modified their food choice, consuming significantly more of the spontaneously preferred food during the pairs interacting and pairs separated conditions, but not during the control condition.

Assembly, secretion, and vacuolar delivery of a hybrid immunoglobulin in plants

Secretory immunoglobulin (Ig) A is a decameric Ig composed of four alpha-heavy chains, four light chains, a joining (J) chain, and a secretory component (SC). The heavy and light chains form two tetrameric Ig molecules that are joined by the J chain and associate with the SC. Expression of a secretory monoclonal antibody in tobacco (Nicotiana tabacum) has been described: this molecule (secretory IgA/G [SIgA/G]) was modified by having a hybrid heavy chain sequence consisting of IgG gamma-chain domains linked to constant region domains of an IgA alpha-chain. In tobacco, about 70% of the protein assembles to its final, decameric structure. We show here that SIgA/G assembly and secretion are slow, with only approximately 10% of the newly synthesized molecules being secreted after 24 h and the bulk probably remaining in the endoplasmic reticulum. In addition, a proportion of SIgA/G is delivered to the vacuole as at least partially assembled molecules by a process that is blocked by the membrane traffic inhibitor brefeldin A. Neither the SC nor the J chain are responsible for vacuolar delivery, because IgA/G tetramers have the same fate. The parent IgG tetrameric molecule, containing wild-type gamma-heavy chains, is instead secreted rapidly and efficiently. This strongly suggests that intracellular retention and vacuolar delivery of IgA/G is due to the alpha-domains present in the hybrid alpha/gamma-heavy chains and indicates that the plant secretory system may partially deliver to the vacuole recombinant proteins expected to be secreted.

t(4;11)(q21;p15) translocation involving NUP98 and RAP1GDS1 genes: characterization of a new subset of T acute lymphoblastic leukaemia

Two cases of T acute lymphoblastic leukaemia (T-ALL) with an identical t(4;11)(q21;p15) translocation were identified within a prospective study on the biological and clinical features of adult ALL patients enrolled into the therapeutic protocol ALL0496 of the GIMEMA Italian Group. In both cases, the molecular characterization showed an involvement of the NUP98 gene on 11p15 which rearranges with the RAP1GDS1 gene on 4q21. The morphological and immunological features of the leukaemic cells, as well as the clinical behaviour and response to induction therapy, were the same in both patients. Based on the available data, the t(4;11)(q21;p15) translocation involving the NUP98-RAP1GDS1 fusion gene emerges as a new highly specific genetic abnormality that characterizes a subset of T-ALL.

CD34(+) acute myeloid and lymphoid leukemic blasts can be induced to differentiate into dendritic cells

CD34(+) hematopoietic stem cells from normal individuals and from patients with chronic myelogenous leukemia can be induced to differentiate into dendritic cells (DC). The aim of the current study was to determine whether acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) cells could be induced to differentiate into DC. CD34(+) AML-M2 cells with chromosome 7 monosomy were cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNFalpha), and interleukin-4 (IL-4). After 3 weeks of culture, 35% of the AML-M2 cells showed DC morphology and phenotype. The DC phenotype was defined as upmodulation of the costimulatory molecules CD80 and CD86 and the expression of CD1a or CD83. The leukemic nature of the DC was validated by detection of chromosome 7 monosomy in sorted DC populations by fluorescence in situ hybridization (FISH). CD34(+) leukemic cells from 2 B-ALL patients with the Philadelphia chromosome were similarly cultured, but in the presence of CD40-ligand and IL-4. After 4 days of culture, more than 58% of the ALL cells showed DC morphology and phenotype. The leukemic nature of the DC was validated by detection of the bcr-abl fusion gene in sorted DC populations by FISH. In functional studies, the leukemic DC were highly superior to the parental leukemic blasts for inducing allogeneic T-cell responses. Thus, CD34(+) AML and ALL cells can be induced to differentiate into leukemic DC with morphologic, phenotypic, and functional similarities to normal DC.

What do proteins need to reach different vacuoles?

Vacuolar proteins begin their life in the endoplasmic reticulum (ER) where they enter the secretory pathway. The information necessary for the correct delivery of soluble proteins to vacuoles has been found in propeptides that might be located at the N-terminus or the C-terminus of the protein, or might be internal. Without these propeptides, vacuolar proteins are secreted. For membrane proteins, both the transmembrane domains and the cytosolic tails are important for sorting to the tonoplast. Available information suggests that soluble proteins destined for the lytic vacuoles are transported through the Golgi complex and then sorted by a receptor that delivers them to a prevacuolar compartment. Proteins destined for the storage vacuoles might or might not travel through the Golgi complex and are packed into large, dense vesicles before being delivered to the storage vacuoles. Sorting of storage proteins occurs along the Golgi complex or in the ER itself and appears to involve self-aggregation.

Ultrasonic vocalizations by infant laboratory mice: a preliminary spectrographic characterization under different conditions

During the first 2 to 3 weeks of life, isolated neonatal mice emit ultrasonic vocalizations, with various conditions such as hypothermia or olfactory or tactile stimulation eliciting this behavior. Although it is known that pup vocalizations stimulate prompt expression of maternal behavior, the communicative role of infant ultrasonic calls is still a matter of investigation. A fine-grained spectrographic analysis of ultrasonic calls emitted by pups exposed to different conditions was performed. Forty 8-day-old outbred CD-1 mice (Mus musculus) were isolated from their mothers and littermates and randomly exposed to one of the following conditions: (a) odor from the nest, (b) social isolation, (c) low temperature-isolation, (d) tactile stimulation, or (e) odor from a conspecific adult male. Upon consideration of the spectrogram typology and emission frequency interval, it appears that the conditions under which vocalizations are emitted influence the sound characteristics of call production.

Course of tic severity in Tourette syndrome: the first two decades

OBJECTIVE

Prevalence studies indicate a 10-fold higher rate of Tourette syndrome (TS) among children compared with adults. The purpose of this investigation was to examine the course of tic severity during the first 2 decades of life.

METHOD

A birth-year cohort of 42 TS patients followed at the Yale Child Study Center was recontacted an average of 7.3 years after their initial clinical evaluation. Data concerning the onset and course of tic severity until 18 years of age were available on 36 TS patients. A variety of statistical techniques were used to model aspects of the temporal patterning of tic severity.

RESULTS

Mean (SD) tic onset at 5.6 (2. 3) years of age was followed by a progressive pattern of tic worsening. On average, the most severe period of tic severity occurred at 10.0 (2.4) years of age. In eight cases (22%), the frequency and forcefulness of the tics reached a severe level during the worst-ever period such that functioning in school was impossible or in serious jeopardy. In almost every case this period was followed by a steady decline in tic severity. By 18 years of age nearly half of the cohort was virtually tic-free. The onset of puberty was not associated with either the timing or severity of tics.

CONCLUSIONS

A majority of TS patients displayed a consistent time course of tic severity. This consistency can be accurately modeled mathematically and may reflect normal neurobiological processes. Determination of the model parameters that describe each patient's course of tic severity may be of prognostic value and assist in the identification of factors that differentially influence the course of tic severity.

Free ricin A chain, proricin, and native toxin have different cellular fates when expressed in tobacco protoplasts

The catalytic A subunit of ricin can inactivate eukaryotic ribosomes, including those of Ricinus communis where the toxin is naturally produced. How such plant cells avoid intoxication has remained an open question. Here we report the transient expression of a number of ricin A chain-encoding cDNA constructs in tobacco protoplasts. Ricin A chain entered the endoplasmic reticulum lumen, where it was efficiently glycosylated, but it was toxic to the cells and disappeared with time in a brefeldin A-insensitive manner, suggesting reverse translocation to the cytosol and eventual degradation. Proricin (the natural precursor form containing A and B chains joined together by a linker sequence) was glycosylated, transported to the vacuole, and processed to its mature form, but was not toxic. Free ricin A chain and proricin were not secreted, whereas free ricin B chain was found entirely in the extracellular medium. The coexpression of ricin A and B chains resulted in the formation of disulfide-linked, transport-competent heterodimers, which were secreted, with a concomitant reduction in the observed cytotoxicity. These results suggest that the production of ricin as a precursor is essential for its routing to the vacuole and for protection of ricin-producing cells.

Sorting of phaseolin to the vacuole is saturable and requires a short C-terminal peptide

Phaseolin, one of the major legume proteins for human nutrition, is a trimeric glycoprotein of the 7S class that accumulates in the protein storage vacuoles of common bean. Phaseolin is cotranslationally introduced into the lumen of the endoplasmic reticulum; from there, it is transported through the Golgi complex to the storage vacuoles. Phaseolin is also transported to the vacuole in vegetative tissues of transgenic plants. By transient and permanent expression in tobacco leaf cells, we show here that vacuolar sorting of phaseolin is saturable and that saturation leads to Golgi-mediated secretion from the cell. A mutated phaseolin, in which the four C-terminal residues (Ala, Phe, Val, and Tyr) were deleted, efficiently formed trimers but was secreted entirely outside of the cells in transgenic tobacco leaves, indicating that the deleted sequence contains information necessary for interactions with the saturable vacuolar sorting machinery. In the apoplast, the secreted phaseolin remained intact; this is similar to what occurs to wild-type phaseolin in bean storage vacuoles, whereas in vegetative vacuoles of transgenic plants, the storage protein is fragmented.

Sorting of phaseolin to the vacuole is saturable and requires a short C-terminal peptide

Phaseolin, one of the major legume proteins for human nutrition, is a trimeric glycoprotein of the 7S class that accumulates in the protein storage vacuoles of common bean. Phaseolin is cotranslationally introduced into the lumen of the endoplasmic reticulum; from there, it is transported through the Golgi complex to the storage vacuoles. Phaseolin is also transported to the vacuole in vegetative tissues of transgenic plants. By transient and permanent expression in tobacco leaf cells, we show here that vacuolar sorting of phaseolin is saturable and that saturation leads to Golgi-mediated secretion from the cell. A mutated phaseolin, in which the four C-terminal residues (Ala, Phe, Val, and Tyr) were deleted, efficiently formed trimers but was secreted entirely outside of the cells in transgenic tobacco leaves, indicating that the deleted sequence contains information necessary for interactions with the saturable vacuolar sorting machinery. In the apoplast, the secreted phaseolin remained intact; this is similar to what occurs to wild-type phaseolin in bean storage vacuoles, whereas in vegetative vacuoles of transgenic plants, the storage protein is fragmented.

BiP and calreticulin form an abundant complex that is independent of endoplasmic reticulum stress

BiP is found in association with calreticulin, both in the presence and absence of endoplasmic reticulum stress. Although the BiP-calreticulin complex can be disrupted by ATP, several properties suggest that the calreticulin associated with BiP is neither unfolded nor partially or improperly folded. (1) The complex is stable in vivo and does not dissociate during 8 hr of chase. (2) When present in the complex, calreticulin masks epitopes at the C terminus of BiP that are not masked when BiP is bound to an assembly-defective protein. And (3) overproduction of calreticulin does not lead to the recruitment of more BiP into complexes with calreticulin. The BiP-calreticulin complex can be disrupted by low pH but not by divalent cation chelators. When the endoplasmic reticulum retention signal of BiP is removed, complex formation with calreticulin still occurs, and this explains the poor secretion of the truncated molecule. Gel filtration experiments showed that BiP and calreticulin are present in distinct high molecular weight complexes in which both molecules interact with each other. The possible functions of this complex are discussed.

BiP and calreticulin form an abundant complex that is independent of endoplasmic reticulum stress

BiP is found in association with calreticulin, both in the presence and absence of endoplasmic reticulum stress. Although the BiP-calreticulin complex can be disrupted by ATP, several properties suggest that the calreticulin associated with BiP is neither unfolded nor partially or improperly folded. (1) The complex is stable in vivo and does not dissociate during 8 hr of chase. (2) When present in the complex, calreticulin masks epitopes at the C terminus of BiP that are not masked when BiP is bound to an assembly-defective protein. And (3) overproduction of calreticulin does not lead to the recruitment of more BiP into complexes with calreticulin. The BiP-calreticulin complex can be disrupted by low pH but not by divalent cation chelators. When the endoplasmic reticulum retention signal of BiP is removed, complex formation with calreticulin still occurs, and this explains the poor secretion of the truncated molecule. Gel filtration experiments showed that BiP and calreticulin are present in distinct high molecular weight complexes in which both molecules interact with each other. The possible functions of this complex are discussed.

Cytotoxic effectors activated by low-dose IL-2 plus IL-12 lyse IL-2-resistant autologous acute myeloid leukaemia blasts

We have investigated the susceptibility of primary acute myeloid leukaemia (AML) samples to the lytic action of normal peripheral blood mononuclear cells (PBMC), as well as of the patients' autologous and allogeneic PBMC collected at the time of remission following stimulation with different concentrations of interleukin (IL)-2 and IL-12, both alone and in variable combinations. Primary AML blasts were resistant to IL-2-activated PBMC effectors generated from normal individuals, allogeneic and autologous patients in five, six and eight of the 10 AML samples tested, respectively, IL-12 alone proved ineffective in generating anti-leukaemic activity, whereas, in combination, the two cytokines induced anti-leukaemic killing in all five cases resistant to normal PBMC, in 4/6 samples resistant to allogeneic AML effectors and in 5/8 cases resistant to autologous effectors. In each case the lytic effect was maintained at the lowest cytokine combination (10 + 10 IU/ml) utilized. The suggestion of a synergistic effect was further strengthened by the evidence that at the lowest doses of IL-2 and IL-12 the degree of killing was greater than that promoted by each cytokine independently. The results of this study suggest that two major limitations associated with the administration of IL-2 to AML patients, the resistance of the blasts to IL-2-generated killing and the toxicity associated with high-dose IL-2, may be overcome by the combined use of very low doses of IL-2 and IL-12. As IL-2-resistant blasts may be lysed by a low-dose combination of IL-2/IL-12, feasibility studies with this cytokine combination are worthy of exploration in vivo.

Protein quality control along the route to the plant vacuole

To acquire information on the relationships between structural maturation of proteins in the endoplasmic reticulum (ER) and their transport along the secretory pathway, we have analyzed the destiny of an assembly-defective form of the trimeric vacuolar storage glycoprotein phaseolin. In leaves of transgenic tobacco, where assembly-competent phaseolin is correctly targeted to the vacuole, defective phaseolin remains located in the ER or a closely related compartment where it represents a major ligand of the chaperone BiP. Defective phaseolin maintained susceptibility to endoglycosidase H and was slowly degraded by a process that is not inhibited by heat shock or brefeldin A, indicating that degradation does not involve transport along the secretory pathway. These results provide evidence for the presence of a quality control mechanism in the ER of plant cells that avoids intracellular trafficking of severely defective proteins and eventually leads to their degradation.

Protein quality control along the route to the plant vacuole

To acquire information on the relationships between structural maturation of proteins in the endoplasmic reticulum (ER) and their transport along the secretory pathway, we have analyzed the destiny of an assembly-defective form of the trimeric vacuolar storage glycoprotein phaseolin. In leaves of transgenic tobacco, where assembly-competent phaseolin is correctly targeted to the vacuole, defective phaseolin remains located in the ER or a closely related compartment where it represents a major ligand of the chaperone BiP. Defective phaseolin maintained susceptibility to endoglycosidase H and was slowly degraded by a process that is not inhibited by heat shock or brefeldin A, indicating that degradation does not involve transport along the secretory pathway. These results provide evidence for the presence of a quality control mechanism in the ER of plant cells that avoids intracellular trafficking of severely defective proteins and eventually leads to their degradation.

Bean (Phaseolus vulgaris L.) protoplasts as a model system to study the expression and stability of recombinant seed proteins

A suitable protocol for the transient expression of seed protein genes in protoplasts derived from cell suspension cultures of common bean has been established. Preliminary analyses of cultures to verify the synthesis of phaseolin - actively accumulated by the starting tissue, the developing cotyledon - showed that the protein was no longer synthesised after 5 days of culture. Transient expression of a phaseolin sequence, driven by a constitutive promoter, resulted in the accumulation of the correctly glycosylated and assembled protein. This system, when compared to tobacco protoplasts, largely avoids phaseolin fragmentation and the presence of contaminant polypeptides in the immunoprecipitates. Therefore, bean protoplasts are a good system to study the expression of wild-type as well as in-vitro-modified bean seed proteins.

Symptoms of obsessive-compulsive disorder

OBJECTIVE

Obsessive-compulsive disorder encompasses a broad range of symptoms that represent multiple psychological domains, including perception, cognition, emotion, social relatedness, and diverse motor behaviors. The purpose of these analyses was to evaluate the correlational relationships of the symptoms of obsessive-compulsive disorder.

METHOD

This study examined the 13 a priori categories used to group types of obsessions and compulsions in the Yale-Brown Obsessive Compulsive Scale symptom checklist in two independent groups of patients with obsessive-compulsive disorder (N = 208 and N = 98). A principal-components factor analysis with varimax rotation was performed, followed by a series of other exploratory analyses.

RESULTS

The two data sets yielded nearly identical results. Four factors--obsessions and checking, symmetry and ordering, cleanliness and washing, and boarding--emerged in each data set, in total accounting for more than 60% of the variance.

CONCLUSIONS

Obsessive-compulsive disorder is a multidimensional and etiologically heterogeneous condition. The four symptom dimensions identified in this study are largely congruent with those identified in earlier reports. These factors may be of value in future genetic, neurobiological, and treatment response studies.

The Rate of Phaseolin Assembly Is Controlled by the Glucosylation State of Its N-Linked Oligosaccharide Chains

Many of the proteins that are translocated into the endoplasmic reticulum are glycosylated with the addition of a 14-saccharide core unit (Glc3Man9GlcNAc2) to specific asparagine residues of the nascent polypeptide. Glucose residues are then removed by endoplasmic reticulum-located glucosidases, with diglucosylated and monoglucosylated intermediates being formed. In this study, we used a cell-free system constituted of wheat germ extract and bean microsomes to examine the role of glucose trimming in the structural maturation of phaseolin, a trimeric glycoprotein that accumulates in the protein storage vacuoles of bean seeds. Removal of glucose residues from the N-linked chains of phaseolin was blocked by the glucosidase inhibitors castanospermine and N-methyldeoxynojirimycin. If glucose trimming was not allowed to occur, the assembly of phaseolin was accelerated. Conversely, polypeptides bearing partially trimmed glycans were unable to form trimers. The effect of castanospermine on the rate of assembly was much more pronounced for phaseolin polypeptides that have two glycans but was also evident when a single glycan chain was present, indicating that glycan clustering can modulate the effect of glucose trimming on the rate of trimer formation. Therefore, the position of glycan chains and their accessibility to the action of glucosidases can be fundamental elements in the control of the structural maturation of plant glycoproteins.