Type 3 and type 1 ryanodine receptors are localized in triads of the same mammalian skeletal muscle fibers

The type 3 ryanodine receptor (RyR3) is a ubiquitous calcium release channel that has recently been found in mammalian skeletal muscles. However, in contrast to the skeletal muscle isoform (RyR1), neither the subcellular distribution nor the physiological role of RyR3 are known. Here, we used isoform-specific antibodies to localize RyR3 in muscles of normal and RyR knockout mice. In normal hind limb and diaphragm muscles of young mice, RyR3 was expressed in all fibers where it was codistributed with RyR1 and with the skeletal muscle dihydropyridine receptor. This distribution pattern indicates that RyR3 is localized in the triadic junctions between the transverse tubules and the sarcoplasmic reticulum. During development, RyR3 expression declined rapidly in some fibers whereas other fibers maintained expression of RyR3 into adulthood. Comparing the distribution of RyR3-containing fibers with that of known fiber types did not show a direct correlation. Targeted deletion of the RyR1 or RyR3 gene resulted in the expected loss of the targeted isoform, but had no adverse effects on the expression and localization of the respective other RyR isoform. The localization of RyR3 in skeletal muscle triads, together with RyR1, is consistent with an accessory function of RyR3 in skeletal muscle excitation-contraction coupling.

Internet agents for telemedicine services

Telemedicine can be defined as telematic support of collaboration between distant medical professionals, co-operating on shared resources of various kinds. Attention should be paid to telematics and informatics concepts, especially those oriented towards collaboration. In particular, the recent agent paradigm seems suitable for the analysis, design and development of telemedicine services because of its commitment to intercommunication and sharing of resources. The present paper is an introduction to the agent paradigm from its theoretical basis to the technological issues, and describes an agent-based approach to telemedicine, specifically applied to telepathology applications. The system is based on an agent-based model and template (JAMES) using Java, which has been used to implement a prototype multipurpose telepathology application based on a federated agency architecture.

Magnetic resonance imaging-monitored conservative management of traumatic spinal epidural hematomas. Report of four cases

Spinal epidural hematomas (SEHs) are uncommon complications of traumatic injury to the spine. Emergency surgical evacuation is the standard treatment. Although it is recognized in the literature, the possibility of nonsurgical treatment of traumatic SEH is far from being codified. The authors report excellent outcomes in four conservatively managed patients who had sustained a severe spine injury with fracture of the lumbar vertebral body and in whom traumatic SEHs were diagnosed by magnetic resonance imaging. Although in the authors' experience a good spontaneous outcome in this subgroup of minimally symptomatic patients harboring moderate-sized SEHs has been achieved, further studies are necessary to understand the real spectrum of nonsurgical treatment of such lesions.

The impact of gender, puberty and body mass on reference values for urinary growth hormone (GH) excretion in normally growing non-obese and obese children

OBJECTIVE

There is a lack of normal reference data on urinary GH (u-GH) excretion in children. We have investigated the impact of age, gender, pubertal development and body mass on reference values for u-GH excretion in normally growing non-obese and obese children.

STUDY DESIGN

u-GH levels were evaluated in 1153 healthy normal children (aged 5-14) and in 684 obese children (body mass index, BMI: > 75th). u-GH levels (ng/8 h) were determined by ELISA as the mean value of three consecutive first morning voidings.

RESULTS

Reference values (5-95th centile) for u-GH excretion in obese and non-obese children of both sexes are reported. In normal prepubertal children median u-GH levels were relatively stable and superimposable in the two sexes; subsequently, u-GH levels increased, reaching a peak value at 13 years in both sexes. Significant increments (P < 0.0001) in u-GH levels were shown at B2 for females and at G3 for males. A slight decline was evident at 14 years. In obese children, median u-GH concentrations were significantly lower than those recorded in normal children of prepubertal age and at all stages of puberty (except in females at B2), in spite of their comparable normal height. u-GH levels significantly increased at puberty also in obese children, although the pubertal rise was significantly (P < 0.001) lower (1.7-fold in both sexes) than that observed in normal children (2.5-fold in boys and 2.3-fold in girls). A multiple regression analysis showed that both chronological age (beta: 0.20), BMI (beta: - 0.11), gender (beta: - 0.04) and pubertal stage (beta: 0.25) contributed significantly to the physiological variation in u-GH levels (multiple R: 0.44, P < 0.00001).

CONCLUSIONS

This study provides reference values for u-GH in normally growing non-obese and obese children, analysing the impact of gender, puberty and body mass on this parameter. In agreement with previous studies, which demonstrate blunted GH-responses to provocative stimuli and reduced nocturnal GH concentration, obese children have significantly lower u-GH levels than age-matched normal weight children, both before and during puberty.

Double-blind randomized study on the myeloprotective effect of melatonin in combination with carboplatin and etoposide in advanced lung cancer

A significant myeloprotective effect of melatonin in mice treated with etoposide, cyclophosphamide or carboplatin has been reported. The present study was designed to evaluate if the same effect could be observed in patients receiving chemotherapy. Twenty previously untreated patients with inoperable lung cancer received two cycles of carboplatin (given at area under the curve 5 by the Calvert formula) on day 1 and etoposide (150 mg m(-2) i.v.) on days 1-3 every 4 weeks. Melatonin 40 mg or placebo (double-blind) was given orally in the evening for 21 consecutive days, starting 2 days before chemotherapy. Patients were randomized to receive melatonin either with the first or the second cycle. Complete blood cell count with differential was done three times per week for 3 weeks. The median age of the cohort was 60 years (range 42-69), 16 patients had non-small cell and four patients small-cell lung cancer, 12 stage III and eight stage IV disease. In a multivariate analysis including age, sex, diagnosis, stage, performance status, doses of carboplatin and etoposide, and concomitant treatment with melatonin or placebo, the haematological parameters--depth and duration of toxicity for haemoglobin, platelets and neutrophils (ANC)--were not significantly different between cycles with/without melatonin. The mean ANC nadir and the mean number of days with ANC < 0.5 x 10(9) l(-1) were 0.5 x 10(9) l(-1) and 2.5 days, respectively, with/without melatonin. We concluded that, in patients with lung cancer, melatonin given orally at a dose of 40 mg per day for 21 days in the evening, does not protect against the myelotoxic effect of carboplatin and etoposide.

Multiple forms of lactadherin (breast antigen BA46) and butyrophilin are secreted into human milk as major components of milk fat globule membrane

In the lactating mammary gland, epithelial cells secrete triacylglycerols in the form of droplets enveloped by an apical surface membrane. This membrane is known as the milk fat globule membrane (MFGM; Mather & Keenan, 1983). MFGM-associated proteins have been studied and employed in developing antibodies against surface antigens of breast epithelial cells, which are used in breast cancer immunodiagnosis and histopathology (Salinas et al. 1987; Larocca et al. 1991; Peterson et al. 1995). So far, only a small number of proteins have been analysed and their sequence identified in bovine, murine and human MFGM; among them are butyrophilin (Jack & Mather, 1990; Ishii et al. 1995; Taylor et al. 1996), MFG-E8 (Stubbs et al. 1990), PAS 6/7 (Hvarregaard et al. 1996) and lactadherin or breast antigen BA46 (Couto et al. 1996; Taylor et al. 1997). Several minor proteins have yet to be characterized, since it is not easy to isolate them in large quantities from the membrane. SDS gel patterns give useful information about MFGM proteins, such as concentration, relative molecular mass and presence of carbohydrate. Over forty membrane components have been separated by electrophoretic techniques from bovine MFGM (Mather et al. 1980).

The research reported here combined SDS-PAGE with sequencing analysis and describes the composition of human MFGM, with the exception of high molecular mass mucin, which only penetrates an acrylamide gel of 40 g/l. Mucins have been extensively studied and the sequence predicted from cDNA (Gendler et al. 1990). Surprisingly, identification of the protein bands in the present study revealed that three proteins alone constituted the major components of human MFGM: xanthine oxidase (EC 1.1.3.22), butyrophilin and lactadherin. Lactadherin belongs to a family of proteins possessing epidermal growth factor-like and factor V/VIII C1/C2-like domains, including bovine PAS 6/7, guinea pig GP55 (Hvarregaard et al. 1996) and murine MFG-E8 (Stubbs et al. 1990). In a previous investigation, we characterized lactadherin (formerly breast antigen BA46) and its truncated 30 kDa form as components of healthy human MFGM (Giuffrida et al. 1998). Human butyrophilin has recently been cloned and sequenced (Taylor et al. 1996); the presence of two extracellular immunoglobulin superfamily domains suggested a potential cell surface receptor function. This study was aimed at identifying and characterizing the multiple forms of the major proteins of MFGM.

Long-term monitoring of rec-GH treatment by serial determination of serum aminoterminal propeptide of type III procollagen in children and adults with GH deficiency

Serum aminoterminal propeptide of type III procollagen (PIIINP) levels, a reliable marker of collagen formation, were evaluated in children (C=7) and adults with childhood-onset (CO=10) and acquired (A=18) GH deficiency (GHD) before, during and after withdrawal of rec-GH therapy (C=0.6 IU/kg/week, CO=0.5 IU/kg/week, A=0.25 IU/kg/week). The duration of treatment was 12 months for C and A and 6 months for CO; investigations were carried out before and at 3, 6, 9 and 12 months (for C and A) and at 3 and 6 months (for CO) of GH treatment and 6 months after the withdrawal of therapy (for A and CO). Data obtained from patients were compared with those recorded in two age- and sex-matched control groups. Before treatment, serum PIIINP levels were significantly lower (p<0.001) in C with GHD (mean+/-SE: 2.9+/-0.4 ng/ml) than in controls (6.1+/-0.4 ng/ml), while no significant differences were recorded between adults with CO/A-GHD (3.7+/-0.5 ng/ml and 3.4+/-0.2 ng/ml) and controls (3.2+/-0.2 ng/ml). GH treatment caused a significant increase (p<0.0001) of PIIINP levels both in C (3rd month: 4.4+/-0.2 ng/ml, 6th month: 5.1+/-0.4 ng/ml, 12th month: 5.1+/-0.5 ng/ml), CO-GHD (3rd month: 12.7+/-1.2 ng/ml; 6th month: 10.2+/-0.6 ng/ml) and A-GHD (3rd month: 10.0+/-1.0 ng/ml; 6th month: 8.4+/-0.6 ng/ml; 12th month: 7.0+/-0.7 ng/ml), the increase being dose-dependent (more marked and sustained in adults with CO-GHD). The maximal stimulation of collagen synthesis occurred after 3 months of GH treatment in adults with GHD, while a more gradual and less relevant increase was observed in C with GHD. Six months after the withdrawal of GH therapy, serum PIIINP levels of adults with CO-GHD (3.6+/-0.3 ng/ml) were similar to those recorded before treatment, while in adults with A-GHD serum PIIINP levels (2.6+/-0.2 ng/ml) were significantly lower (p<0.01) than in basal condition. In conclusion, our study shows that: a) GHD is associated with a reduction of soft tissue formation in children, while it seems to exert no relevant effects in adults with GHD; b) GH therapy causes a rapid stimulation of collagen turnover, which shows a different pattern in children and adults; c) the GH-induced stimulation of collagen synthesis is rapidly removed after the withdrawal of GH treatment. For these reasons, the determination of peripheral markers of GH effects appears useful for the monitoring of GH therapy and can contribute to assess the "tailored" substitutive dose for the individual patient.

The major allergen of peach (Prunus persica) is a lipid transfer protein

BACKGROUND

Allergy to fresh fruits and vegetables is mostly observed in subjects with pollinosis, especially from birch, because of cross-reacting allergens in vegetable foods and pollens. However, allergic reactions to fruits, specifically Rosaceae fruits, have been reported in subjects without pollinosis.

OBJECTIVE

This study evaluated the pattern of IgE reactivity, identifying the allergen responsible in 2 groups of patients with oral allergy syndrome to peach with or without birch pollinosis.

METHODS

The allergenic components of peach were detected by SDS-PAGE and immunoblotting. The major peach allergen was purified by HPLC with a cation-exchange column followed by gel filtration chromatography. Its IgE-binding capacity and its homology with the protein of the crude extract were demonstrated by immunoblotting inhibition techniques. To better characterize this allergen, periodic acid-Schiff stain and isoelectrofocusing were used. The amino acid sequencing was done with a gas-phase sequencer.

RESULTS

SDS-PAGE and immunoblotting of the 15 patients allergic to peach, 8 without and 7 with birch pollinosis, showed that they all recognized a protein with a molecular weight of 9 kd. This was the only allergen recognized by patients not sensitized to pollen, whereas the birch pollen-sensitive patients had IgE binding to other allergenic proteins at higher molecular weights. The purified 9-kd protein retained its IgE-binding capacity, was negative to periodic acid-Schiff stain, and had an isoelectric point value of greater than 9. A search in the Swiss Prot Bank showed this was a lipid transfer protein, belonging to a group of molecules involved in the defensive system of plants.

CONCLUSIONS

The major allergen of peach is a 9-kd protein belonging to the group of lipid transfer proteins. This is the only allergen recognized by patients allergic to peach but not sensitized to birch pollen.

Total hip disarticulation prosthesis with suction socket: report of two cases

A majority of hip disarticulations are performed in young people, with malignancy being the most common cause. The exoskeletal Canadian Hip Disarticulation prosthesis had been widely used as a standard total hip disarticulation prosthesis until recently when an endoskeletal modular version became the prosthesis of choice. However, the "basket-shaped" socket provided by the standard total hip disarticulation prostheses has been a source of discomfort and a reason for prosthetic rejection by many patients. This report concerns two patients with true lower limb disarticulation at the hip joint. Both of the patients failed to adapt to the standard total hip disarticulation prosthesis but successfully used a new total contact suction socket design. This new prosthesis provided improved suspension, better patient compliance, and enhanced prosthetic acceptance and mobility.

Absence in human milk of bovine beta-lactoglobulin ingested by the mother. Unreliability of ELISA measurements

OBJECTIVES

To analyze the presence of bovine beta-LG in breast milk.

METHODS

Human milk samples from 14 healthy non-atopic women on diets with different cow's milk contents were examined. The total concentration of beta-LG immuno-like proteins (beta-LGIP) was determined by enzyme linked immunosorbent assay (ELISA). Identification of antigens was done by N-terminal sequencing.

RESULTS

beta-LGIP reactivity of the milk from subjects on different diets was not significantly different. Human lactoferrin, beta-casein and alpha-lactalbumin, were identified as cross-reacting antigens.

CONCLUSIONS

False-positive results in ELISA determinations of bovine beta-LG in human milk might be due to cross-reactions between polyclonal antibodies and different protein antigens.

Giant retroperitoneal angiomyolipoma. A case report

We discuss a case of a giant renal angiomyolipoma. A 28 year-old woman presented with a history of a painless and swelling abdominal mass. A computerized tomography (CT) scan of the abdomen demonstrated a 27 x 13 x 11 cm tumor in the right retroperitoneum. At laparotomy, a wide excision of the mass was performed and the histopathological examination of the resected specimen revealed the presence of an angiomyolipoma. The clinical, radiological and pathological findings of this case are reported with a review of the literature.

Sensitization to the major allergen of Brazil nut is correlated with the clinical expression of allergy

BACKGROUND

Only a few studies have investigated the clinical role of food allergens, especially the relationship between sensitization to a given allergen and occurrence of adverse reactions when eating the relevant food item.

OBJECTIVE

This study evaluated the clinical role of the allergens of Brazil nut by comparing the patterns of IgE binding in sera from 11 patients with anaphylaxis after eating Brazil nuts with those from 10 subjects with no symptoms to this food item. Both groups had specific IgE to Brazil nut.

METHODS

Allergens in the in-house extract of Brazil nut were identified by SDS-PAGE/immunoblotting, the major allergen was purified by HPLC, and its N-terminal sequence was determined by a protein sequencer.

RESULTS

SDS-PAGE/immunoblotting detected a number of allergenic components with molecular weights ranging from 4 to 58 kd. All sera from symptomatic patients recognized a 9-kd allergen corresponding (as established by amino acid sequencing) to a 2S albumin already described as a major allergen of Brazil nut, whereas the other allergens each bound IgE from less than 50% of sera. No sera from asymptomatic subjects showed IgE binding to the 9-kd allergen, but they did recognize components from 25 to 58 kd, which are minor allergens.

CONCLUSIONS

These findings indicate that the allergen underlying clinical reactions to Brazil nut is a 2S albumin of 9 kd and that in vitro reactivity to this allergen identifies subjects who react in vivo to ingestion of this food.

Evidence for a common epitope between bovine alpha-lactalbumin and beta-lactoglobulin

The aim of this work was to check and quantify any cross-reactivities among the main bovine whey proteins, utilizing purified polyclonal antibodies against bovine beta-lactoglobulin, alpha-lactalbumin and serum albumin, and to identify possible common epitope(s). Purified polyclonal anti-bovine beta-lactoglobulin antibodies show 10% cross-reactivity with bovine alpha-lactalbumin, both in its native and its denatured form. A continuous stretch of four amino acids common to alpha-lactalbumin and beta-lactoglobulin that might be responsible for this cross-reactivity has been identified. Cross-reactivity between this antibody and bovine serum albumin is, on the contrary, negligible. Purified polyclonal anti-bovine alpha-lactalbumin and anti-serum albumin antibodies do not cross-react.

Neural and endogenous catecholamines in the bone marrow. Circadian association of norepinephrine with hematopoiesis?

Members of our research team have recently reported that adrenergic agents may affect hematopoiesis via alpha1-adrenoceptors present on bone marrow B cell precursors. In this paper we demonstrate that murine bone marrow contains a substantial amount of catecholamines. Norepinephrine (NE) and dopamine (DA) exhibited a daily rhythmicity, with peak values observed during the night. The rhythm was disrupted by chemical sympathectomy, whereas epinephrine (E) showed no rhythmicity or sensitivity to 6-hydroxydopamine. High and low values of NE and DA were associated with high and low values of their metabolites, which indicated a rhythmic catecholamine release. NE, but not DA or E, was positively associated with the proportion of cells in the G2/M and S phases of the cell cycle. Moreover, NE and DA were found in both short-term and long-term bone marrow cultures as well as in human or murine B lymphoid cell lines. These findings indicate that endogenous catecholamines in the bone marrow have both neural and cellular origins. The neural input shows a daily rhythm and may be implicated in the regulation of hematopoiesis.

Melatonin rhythms in mice: role in autoimmune and lymphoproliferative diseases

Production of melatonin (MLT) in the pineal gland (PG) of inbred mice such as C57BI/6J, BALB/c, and AKR strains is still a matter of debate. In a recent study we validated the presence of MLT in the PG of these inbred mice. We found a short-term MLT peak in the middle of the dark period with a pattern that mirrors that found previously in the serum. In another study, based on the known immunoregulatory role of MLT, we investigated the role of the PG and MLT in autoimmune diabetes mellitus type I using, as an experimental model, female nonobese diabetic (NOD) mice. Mice were pinealectomized or treated chronically with MLT (injected subcutaneously or administered via drinking water). We found that neonatal pinealectomy accelerates the development of disease in female NOD mice, whereas exogenous MLT protects animals. This is in spite of the fact that MLT increased the production of insulin autoantibodies (IAA). We conclude that PG and MLT influence the development of autoimmune diabetes, although the mechanism of action needs further investigation.

Functional properties of the ryanodine receptor type 3 (RyR3) Ca2+ release channel

Single-channel analysis of sarcoplasmic reticulum vesicles prepared from diaphragm muscle, which contains both RyR1 and RyR3 isoforms, revealed the presence of two functionally distinct ryanodine receptor calcium release channels. In addition to channels with properties typical of RyR1 channels, a second population of ryanodine-sensitive channels with properties distinct from those of RyR1 channels was observed. The novel channels displayed close-to-zero open-probability at nanomolar Ca2+ concentrations in the presence of 1 mM ATP, but were shifted to the open conformation by increasing Ca2+ to micromolar levels and were not inhibited at higher Ca2+ concentrations. These novel channels were sensitive to the stimulatory effects of cyclic adenosine 5'-diphosphoribose (cADPR). Detection of this second population of RyR channels in lipid bilayers was always associated with the presence of the RyR3 isoform in muscle preparations used for single-channel measurements and was abrogated by the knockout of the RyR3 gene in mice. Based on the above, we associated the novel population of channels with the RyR3 isoform of Ca2+ release channels. The functional properties of the RyR3 channels are in agreement with a potential qualitative contribution of this channel to Ca2+ release in skeletal muscle and in other tissues.

5 alpha-reductase inhibitors, chemical and clinical models

An active site model of 5 alpha-reductase type 2 isoenzyme on an "active-analog approach" and based on 4-azasteroidal inhibitors has been constructed to evaluate the effects on the inhibitory potency of substituents on the steroid A ring. This model has proven able to predict the potential inhibitory activity of 19-nor-10-azasteroid and 6-azasteroid compounds. A model for the evaluation of clinical efficacy of an inhibitor, based on in vitro data, has also been developed and applied to finasteride. This inhibitory potency evaluation of finasteride in human scalp homogenates, plus pharmacokinetic data, allows the calculation of a theoretical in situ inhibition value for human scalp. From the IC50 curve of finasteride in scalp homogenates, it is possible to calculate that for an inhibition level similar to that obtained in prostate with 5 mg of finasteride, the necessary plasma concentration of the drug is 1 microM, a level obtained after the acute administration of 50 mg of finasteride.

Melatonin rhythms in mice: role in autoimmune and lymphoproliferative diseases

Production of melatonin (MLT) in the pineal gland (PG) of inbred mice such as C57BI/6J, BALB/c, and AKR strains is still a matter of debate. In a recent study we validated the presence of MLT in the PG of these inbred mice. We found a short-term MLT peak in the middle of the dark period with a pattern that mirrors that found previously in the serum. In another study, based on the known immunoregulatory role of MLT, we investigated the role of the PG and MLT in autoimmune diabetes mellitus type I using, as an experimental model, female nonobese diabetic (NOD) mice. Mice were pinealectomized or treated chronically with MLT (injected subcutaneously or administered via drinking water). We found that neonatal pinealectomy accelerates the development of disease in female NOD mice, whereas exogenous MLT protects animals. This is in spite of the fact that MLT increased the production of insulin autoantibodies (IAA). We conclude that PG and MLT influence the development of autoimmune diabetes, although the mechanism of action needs further investigation.

Urinary free deoxypyridinoline levels during childhood

Free urinary deoxypyridinoline (DPD) levels, corrected for the urinary concentration of creatinine (nmol/mmol), were determined in 144 healthy children (76 males and 68 females, mean age +/- SE: 9.1 +/- 0.2 yr, age range: 5.1-14.0 yr) in order to detect the possible age-related changes of this reliable index of bone resorption activity and the relationship between free DPD, gender and pubertal development. Multiple regression analysis revealed that most of the variation in DPD levels was explained by chronological age (coefficient: 2.89, p < 0.02), whereas sex and pubertal stage did not add significance to the variance. Urinary DPD levels were similar in males (24.7 +/- 1.8 nmol/mmol urinary creatinine) and females (24.2 +/- 2.0 nmol/mmol urinary creatinine) and significantly higher (p < 0.02) in pubertal (Tanner stage II-V: 28.6 +/- 2.8 nmol/mmol urinary creatinine) than in prepubertal children (22.4 +/- 1.4 nmol/mmol urinary creatinine), both in males and in females. The pattern of DPD levels was clearly different between females and males, the maximum increase being evident at Tanner stage II-III (mid-puberty) in females and at Tanner stage IV-V (mid-late puberty in males. The increase of DPD paralleled the elevation of urinary GH (pmol/mmol urinary creatinine), a non-invasive and acceptable index of physiological GH secretion, observed during the pubertal growth spurt. The progressive increase of urinary GH in older children was not followed by a further stimulation of bone resorption. Although the relationships between urinary, GH and DPD need to be better investigated, it seems plausible to hypothesize that the determination of urinary free DPD, as a marker of GH action on bone, might have some potential in the follow-up of growth promoting treatments, such as GH.

Identification of actinidin as the major allergen of kiwi fruit

BACKGROUND

Allergic reactions to fruits and vegetables are among the most frequent food allergies in adults. Kiwi fruit (Actinidia chinensis) is commonly involved, causing local mucosal, systemic, or both types of symptoms by an IgE-mediated mechanism. In a previous study on 30 patients allergic to kiwi, we identified a major allergen of 30 kd against which all sera tested clearly reacted. Other allergens were detected at 12, 24, and 28 kd.

OBJECTIVE

The aim of this study was to fully characterize the major kiwi fruit allergen of 30 kd.

METHODS

Allergens were separated and purified by high-performance liquid chromatography with anion-exchange columns. The purity of the single proteins was checked by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and their allergenicity was checked by immunoblotting with a pool of sera from patients allergic to kiwi. The allergens were characterized by isoelectrofocusing and amino acid sequencing, and periodic acid-Schiff stain was used to detect glycoproteins.

RESULTS

Proteins of 30, 28, 24, and 17 kd were purified by high-performance liquid chromatography. IgE binding indicated the 30 kd protein, which showed an isoelectric point of 3.5, as the major allergen of kiwi. Determination of its partial amino acid sequence and comparison with the Swiss Protein Bank showed that this was actinidin, the main protein component of kiwi. The 24 and 28 kd proteins had the same N-terminal sequence, which did not correspond to any known protein. The 17 kd protein had a blocked N-terminal sequence.

CONCLUSIONS

These results demonstrate that the major allergen of kiwi fruit, Act c 1, is actinidin, a proteolytic enzyme belonging to the class of thiol-proteases. Two other allergens of 24 and 28 kd appear identical on amino acid sequencing.